EP3577068A1 - Liquid process for preparing a vanadium phosphate-carbon composite material - Google Patents

Liquid process for preparing a vanadium phosphate-carbon composite material

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Publication number
EP3577068A1
EP3577068A1 EP18712940.8A EP18712940A EP3577068A1 EP 3577068 A1 EP3577068 A1 EP 3577068A1 EP 18712940 A EP18712940 A EP 18712940A EP 3577068 A1 EP3577068 A1 EP 3577068A1
Authority
EP
European Patent Office
Prior art keywords
composite material
compound
acid
carbon
vanadium
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP18712940.8A
Other languages
German (de)
French (fr)
Inventor
Rénald DAVID
Christine SURCIN
Mathieu Morcrette
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Centre National de la Recherche Scientifique CNRS
Universite de Picardie Jules Verne
Original Assignee
Centre National de la Recherche Scientifique CNRS
Universite de Picardie Jules Verne
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Centre National de la Recherche Scientifique CNRS, Universite de Picardie Jules Verne filed Critical Centre National de la Recherche Scientifique CNRS
Publication of EP3577068A1 publication Critical patent/EP3577068A1/en
Pending legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/16—Oxyacids of phosphorus; Salts thereof
    • C01B25/26—Phosphates
    • C01B25/37—Phosphates of heavy metals
    • C01B25/372—Phosphates of heavy metals of titanium, vanadium, zirconium, niobium, hafnium or tantalum
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    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/16—Oxyacids of phosphorus; Salts thereof
    • C01B25/26—Phosphates
    • C01B25/455—Phosphates containing halogen
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    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/05—Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30
    • H—ELECTRICITY
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    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/01—Crystal-structural characteristics depicted by a TEM-image
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    • C01P2002/02—Amorphous compounds
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    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
    • C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
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    • C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
    • C01P2002/74—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by peak-intensities or a ratio thereof only
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
    • C01P2002/76—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by a space-group or by other symmetry indications
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    • C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
    • C01P2002/77—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by unit-cell parameters, atom positions or structure diagrams
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    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/80—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70
    • C01P2002/88—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70 by thermal analysis data, e.g. TGA, DTA, DSC
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    • C01—INORGANIC CHEMISTRY
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    • C01P2004/00—Particle morphology
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    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
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    • C01P2006/40—Electric properties
    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
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    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the invention relates to a process for the preparation of a vanadium-carbon phosphate composite material, a vanadium-carbon phosphate composite material obtained according to the method, and to the uses of said composite material, especially as a precursor for the synthesis of electrochemically active materials. electrode or active anode material.
  • a lithium battery (respectively a sodium battery) comprises at least one negative electrode and at least one positive electrode between which is placed a solid electrolyte or a separator impregnated with a liquid electrolyte.
  • the liquid electrolyte consists of a lithium salt (or a sodium salt) dissolved in a solvent chosen to optimize the transport and dissociation of the ions.
  • the positive electrode is constituted by a current collector supporting an electrode material which contains at least one positive electrode active material capable of inserting lithium ions (respectively sodium ions) in a reversible manner;
  • the negative electrode consists of a sheet of lithium (respectively sodium) metal (optionally supported by a current collector), a lithium alloy (respectively sodium) or an intermetallic lithium compound (respectively sodium) ) (lithium battery) (respectively sodium battery), or by a current collector supporting an electrode material which contains at least one negative electrode active material capable of inserting lithium ions (respectively sodium ions) of reversible way (lithium ion battery: Li-ion) (respectively to sodium ions: Na-ion).
  • Each electrode material generally further comprises a polymer which acts as a binder (eg polyvinylidene fluoride or PVdF) and / or a conferring agent.
  • a polymer which acts as a binder (eg polyvinylidene fluoride or PVdF) and / or a conferring agent.
  • electronic conductivity eg carbon
  • an ionically conductive compound eg lithium salt
  • sodium salt eg sodium salt
  • lithium ions pass from one to the other of the electrodes through the electrolyte.
  • a quantity of lithium (respectively sodium) reacts with the positive electrode active material from the electrolyte, and an equivalent amount is introduced into the electrolyte from the active ingredient of the negative electrode, the concentration of lithium (respectively sodium) thus remaining constant in the electrolyte.
  • the insertion of lithium (respectively sodium) into the positive electrode is compensated by supplying electrons from the negative electrode via an external circuit. During charging, the reverse phenomena take place.
  • the gel obtained is then dried at 100 ° C. for 12 hours, to form a powder which is pressed in the form of pellets.
  • the pellets are then heated at 350 ° C. for 4 hours under argon and glucose as a carbon source is ground with the pellets.
  • the resulting mixture is finally calcined at 750 ° C. for 12 hours under argon.
  • this type of process comprises a large number of steps and remains very long.
  • the intimate grinding step between the vanadium phosphate precursor and the glucose is critical to obtain a homogeneous carbon coating.
  • this process uses NH 4 H 2 PO 4 which produces ammonia, making it difficult to industrialize.
  • V 2 O 5 and NH 4 H 2 PO 4 are heated at 300 ° C. for 8 h under dihydrogen, cooled, milled and then heated at 850 ° C. for 8 h under dihydrogen.
  • the vanadium phosphate must then be contacted with a carbon source such as glucose in an additional step.
  • NH 4 H 2 PO 4 releases nitrous under a reducing atmosphere which deteriorates the walls of the appliances / reactors used.
  • the grinding or mechanosynthesis steps used in the aforementioned methods are expensive.
  • the hydrothermal route has also been proposed to produce a material based on vanadium phosphate and possibly carbon.
  • this route requires the use of very high pressures and / or an autoclave that increase the cost of production.
  • the object of the present invention is therefore to overcome all or part of the disadvantages of the aforementioned prior art, and in particular to provide a simple method (eg which has few steps) and inexpensive for the preparation of a material composite based on vanadium phosphate and carbon, while avoiding the release of harmful gases such as ammonia.
  • the invention therefore firstly relates to a method for preparing a vanadium and carbon phosphate composite material having the formula VP0 4 / C, characterized in that it comprises the following steps:
  • step ii) heating the mixture of step i) at a temperature of about 35 ° C to 100 ° C, to form a solid residue
  • the process of the invention allows in a few steps and economically, to directly form a composite material of vanadium phosphate and carbon, while avoiding the release of harmful gases such as ammonia.
  • Step i) is generally carried out at a temperature ranging from 15 to
  • aqueous suspension comprising the vanadium precursor, H 3 PO 4 (as phosphate precursor), the compound A chosen from the compound comprising at least one carboxylic acid function and the polysaccharide compound, and optionally the precursor compound of carbon.
  • the aqueous solvent is preferably water, especially distilled water.
  • the vanadium precursor is preferably V 2 0 5 .
  • the molar ratio [H 3 PO 4 / vanadium element in the vanadium precursor] generally varies from about 1 to 1.5.
  • the mass concentration of vanadium precursor (eg V 2 0 5 ) in the aqueous suspension at the end of step i) ranges from about 0.1% to about 25% by weight, and preferably from 0.5 to 15% by weight. % by mass approximately.
  • the compound comprising at least one carboxylic acid function (compound Ai) acts as a chelating agent.
  • the compound Al or the precursor compound of carbon (compound B) will make it possible to form a layer of carbon enveloping the particles of VP0 4 .
  • compound Ai may be the same as or different from a carbon precursor.
  • compound Ai When the compound comprising at least one carboxylic acid function (compound Ai) is also a precursor of carbon, it plays both the role of chelating agent and precursor of carbon. The addition of a precursor compound of carbon is therefore not necessary.
  • a carbon precursor compound (compound B) When the compound comprising at least one carboxylic acid function (compound Ai) is not a precursor of carbon, a carbon precursor compound (compound B) must be used.
  • the polysaccharide compound (compound A 2 ) has the advantage of acting as both a chelating agent and a precursor of carbon.
  • the compound comprising at least one carboxylic acid function is a polycarboxylic acid, and more preferably it comprises two or three carboxylic acid functions.
  • the compound comprising at least one carboxylic acid function comprises from 2 to 10 carbon atoms, and preferably from 2 to 6 carbon atoms.
  • the compound comprising at least one carboxylic function may also contain one or more hydroxyl functional groups, especially in the ⁇ -position of a carboxylic acid function.
  • the compound comprising at least one carboxylic acid function may be chosen from saturated carboxylic or polycarboxylic acids such as oxalic acid, citric acid, glycolic acid, lactic acid, tartaric acid, malic acid, succinic acid, glycolic acid, malonic acid, glutaric acid, adipic acid, acid isocitric acid, oxalosuccinic acid, tricarballylic acid and unsaturated carboxylic or polycarboxylic acids such as maleic acid, fumaric acid and aconitic acid.
  • saturated carboxylic or polycarboxylic acids such as oxalic acid, citric acid, glycolic acid, lactic acid, tartaric acid, malic acid, succinic acid, glycolic acid, malonic acid, glutaric acid, adipic acid, acid isocitric acid, oxalosuccinic acid, tricarballylic acid and unsaturated carboxylic or polycarboxylic acids such as maleic acid, fumaric acid and acon
  • Saturated carboxylic or polycarboxylic acids are preferred.
  • the molar ratio [compound comprising at least one carboxylic acid function (compound Al) / vanadium element in the vanadium precursor] is generally at least 1, and preferably varies from 1 to about 2, and more preferably from 1, About 02 to 1.5. This makes it possible to optimize the electrochemical performances.
  • the molar ratio [polysaccharide compound (A 2 compound) / vanadium element in the vanadium precursor] is generally at least 0.01, and preferably ranges from about 0.1 to about 0.6. This makes it possible to optimize the electrochemical performances.
  • the carbon precursor compound (compound B) may be a polyol such as a diol or a triol.
  • the carbon precursor compound (compound B) is chosen from ethylene glycol and glycerol.
  • the molar ratio [carbon precursor compound (compound B) / vanadium element in the vanadium precursor] preferably varies from 0.05 to 2 approximately, and more preferably from 0.25 to 0.45 approximately.
  • the polysaccharide compound (compound A 2 ) may be chosen from polysaccharides comprising agarose and / or agaropectin and carrageenates.
  • the polysaccharide compound (compound A 2 ) is a polysaccharide comprising agarose and / or agaropectin such as agar-agar.
  • the mixture of step i) comprises either citric acid (as a compound comprising at least one carboxylic acid function) or oxalic acid. (as a compound comprising at least one carboxylic acid function) and ethylene glycol or glycerol (as a precursor compound for carbon), or agar agar (as polysaccharide compound).
  • Step i) generally lasts from about 1 to 60 minutes. Step i) is preferably a mechanical mixture.
  • the mixture of step i) may further comprise a polyol such as a diol or a triol, especially when the compound A is a compound comprising at least one carboxylic acid function (compound Ai) which is a precursor of carbon, or a polysaccharide compound (compound A 2 ).
  • a polyol such as a diol or a triol, especially when the compound A is a compound comprising at least one carboxylic acid function (compound Ai) which is a precursor of carbon, or a polysaccharide compound (compound A 2 ).
  • the polyol may be chosen from ethylene glycol and glycerol.
  • the mixture of step i) may further comprise a binder.
  • the binder can make it possible to avoid the increase of volume during the implementation of the process of the invention, and thus can freeze the system, making it easily industrializable.
  • the binder may be chosen from synthetic polymers such as polyvinyl alcohol, polyethylene glycol, polyvinylpyrrolidone, polyacrylonitrile, polyformaldehyde, polylactic acid or polyitaconates; biopolymers such as polysaccharides, polysaccharide derivatives or polypeptides; and one of their mixtures.
  • the proportion of binder in the solid mixture of step i) preferably ranges from about 0% to about 50% by weight, and more preferably from about 10% to about 30% by weight.
  • the solid mixture does not take into account the aqueous solvent. It therefore comprises the vanadium precursor, H 3 PO 4 , the compound A 1 or A 2 , and the compound B if it exists.
  • Step ii) makes it possible to evaporate the aqueous solvent to form a solid residue.
  • Step ii) is generally conducted under air, in particular using a hot plate.
  • step ii) lasts from 1h to 12h approximately.
  • Step ii) is preferably carried out with magnetic stirring.
  • Steps i) and ii) can be concomitant.
  • Step iii) preferably lasts at least about 30 minutes, and more preferably at least about 1 hour.
  • step iii) lasts not more than about 8 hours, preferably not more than about 5 hours, and more preferably not more than about 3 hours.
  • Step iii) is preferably conducted at a temperature greater than 860 ° C, more preferably from about 870 ° C to 910 ° C, and more preferably from about 880 ° C to about 900 ° C.
  • Step iii) can be carried out under argon or under air.
  • Step iii) can be implemented in a closed or open container.
  • the method may further comprise a step iv) in which the composite material obtained at the end of step iii) is cooled, especially at room temperature (i.e., about 20-25 ° C).
  • Step iv) can be carried out using water, and preferably cold water (cold water temperature below room temperature, e.g. below about 20-25 ° C).
  • the process does not preferably include grinding stage (s) and / or mechanosynthesis (well known under the term "lease milling").
  • the process may further comprise step ii ') between steps ii) and iii) during which the solid residue is heated to a temperature of about 200 to 400 ° C, in particular for a period of about 30 minutes to about 2 hours. This step ii ') can be carried out in an oven.
  • Step ii ') may make it possible to contain a possible volume increase in an open environment.
  • the method preferably does not include other heating step (s) than steps ii), ii ') and iii).
  • the method preferably does not involve the implementation of high pressures (e.g. pressures of the order of 3 bars) and / or the use of an autoclave.
  • high pressures e.g. pressures of the order of 3 bars
  • the subject of the invention is a composite material of vanadium and carbon phosphate, characterized in that it is obtained according to a process according to the first subject of the invention.
  • the composite material of the invention comprises particles of VP0 4 coated with an amorphous carbon layer.
  • the vanadium and carbon phosphate composite material of the invention has the advantage of leading to electrochemically active electrode materials which exhibit improved electrochemical performance over those obtained from a vanadium phosphate material and carbon of the prior art.
  • the invention therefore has for third object the use of a composite material of vanadium phosphate and carbon as obtained according to the process according to the first subject of the invention as a precursor for the preparation of electrochemically active electrode materials and in particular active materials of polyanionic type cathodes such as Na 3 V 2 (PO 4 ) 2 F 3 / C, Na 3 V 2 (PO 4 ) 3 / C or LiVPO 4 F / C.
  • the fourth subject of the invention is the use of a composite material of vanadium and carbon phosphate as obtained according to the process according to the first subject of the invention as anode active material.
  • the fifth subject of the invention is a composite material of the formula Na 3 V 2 (O 4 ) 2 F 3 / C, characterized in that it is obtained from a composite material of vanadium phosphate and of carbon of formula VPO 4 / C according to the second subject of the invention or obtained by a method according to the first subject of the invention.
  • the composite material Na 3 V 2 (O 4 ) 2 F 3 / C of the invention has a higher Vanadium III / Vanadium IV molar ratio than that of the composite materials of the prior art. This allows to obtain improved electrochemical performance.
  • This upper molar ratio is preferably translated by a parameter of mesh c greater than or equal to 10.752 ⁇ .
  • the inventors have surprisingly discovered that the composite material Na 3 V 2 (PO 4 ) 2 F 3 / C of the invention has a higher typed density than the composite materials of the prior art.
  • the density typed is preferably measured using a volumetric, including a volumeter sold under the trade name STAV II by the company J. Engelsmann AG, preferably with the following parameters: volume of 250 ml and 1250 strokes.
  • the typed density is obtained according to the conditions of the European Pharmacopoeia, DIN ISO 787 Part 11, ISO 3953, and ASTM B 527-93.
  • the typed density of the Na 3 V 2 (PO 4 ) 2 F 3 / C composite material of the invention is preferably greater than about 0.5 g / cm 3 , and preferably greater than about 1 g / cm 3 .
  • the typed density of the composite material Na 3 V 2 (PO 4 ) 2 F 3 / C varies from approximately 0.5 to 3.16 g / cm 3 , and more preferably about 1 to 2 g / cm 3 .
  • This composite material can be obtained from a composite material of vanadium phosphate and carbon of formula VP0 4 / C according to the second subject of the invention or obtained by a process according to the first subject of the invention.
  • V 2 O 5 vanadium oxide
  • H 3 PO 4 phosphoric acid
  • oxalic acid 0.9 g of ethylene glycol
  • the tube was then cooled to room temperature using water.
  • the composite material 1 obtained in the form of a powder was analyzed by X-ray diffraction (XRD) using a diffractometer sold under the trade name D8 by Bruker (CuKa radiation). The samples were scanned between 16 and 50 ° 2 ⁇ .
  • XRD X-ray diffraction
  • FIG. 1 represents an X-ray diffraction pattern of the composite material 1 of the formula VP0 4 / C.
  • the amount of carbon in the composite material 1 of the formula VP0 4 / C was analyzed by thermogravimetric analysis (TGA). A heating rate of about 10 ° C. per minute was used from about 25 ° C. to about 680 ° C. and a plateau at 680 ° C. for 1 hour was performed. The composition of the gas phase was monitored in parallel with mass spectroscopic (MS) heating. It was approximately 4.8% by weight, based on the total mass of composite material.
  • TGA thermogravimetric analysis
  • the composite material 1 was also analyzed by transmission electron microscopy (TEM) using a microscope sold under the trade name FEI TECNAI G2 by the company FEI.
  • TEM transmission electron microscopy
  • FIG. 2 represents a TEM image of the composite material 1. It confirms the presence of a carbon shell with a thickness of about 5 nm, enveloping the vanadium phosphate.
  • V 2 O 5 vanadium oxide
  • H 3 PO 4 phosphoric acid
  • citric acid citric acid
  • the resulting mixture was heated at 85 ° C with magnetic stirring for 12h to evaporate the water.
  • the residue obtained was heated at 890 ° C. for 1 h in a quartz tube under an argon atmosphere.
  • the tube was then cooled to room temperature using water.
  • the composite material 2 obtained in the form of a powder was analyzed by X-ray diffraction (XRD) using an apparatus as described in Example 1. The samples were scanned between 16 and 50 ° 2 ⁇ .
  • the x-ray diffraction pattern of the composite material 2 of the formula VP0 4 / C was similar to that obtained for the composite material of Example 1 (see FIG.
  • the TEM image of the composite material 2 of the formula VP0 4 / C was similar to that obtained for the composite material of Example 1 (see FIG.
  • VP0 4 / C was analyzed by ATG as in Example 1. It was 4.5% by weight approximately, based on the total mass of composite material.
  • V 2 O 5 vanadium oxide
  • H 3 PO 4 phosphoric acid
  • oxalic acid 0.9 g of ethylene glycol
  • the resulting mixture was heated at 85 ° C with magnetic stirring for 12h to evaporate the water.
  • the resulting residue was heated at 850 ° C for 10 h in a quartz tube under an argon atmosphere. The tube was then cooled to room temperature using water.
  • the material A obtained in the form of a powder was analyzed by X-ray diffraction (XRD) using an apparatus as described in Example 1. The samples were scanned between 20 and 40 ° 2 ⁇ .
  • FIG. 3 represents an X-ray diffraction pattern of material A, showing an amorphous material very different from composite materials 1 and 2 respectively obtained in Examples 1 and 2.
  • Example 2 4 g of a composite material of formula VP0 4 / C as obtained in Example 1 were mixed with 1.22 g of NaF for 12 hours using a Turbula-type space mixer comprising a bead. Then, the resulting mixture was heated at 700 ° C for 1 h in a quartz tube under an argon atmosphere.
  • the tube was then cooled to room temperature using water.
  • the composite material 3 of formula Na 3 V 2 (PO 4 ) 2 F 3 / C obtained in the form of a powder was analyzed by X-ray diffraction (XRD) using an apparatus as described in FIG. example 1. The samples were scanned between 16 and 50 ° 2 ⁇ . The Rietveld model was used to refine the mesh parameters of the materials.
  • FIG. 4 represents an X-ray diffraction pattern of the composite material 3 of formula Na 3 V 2 (PO 4 ) 2 F 3 / C, as well as a TEM image of said composite material 3.
  • the typed density of the composite material Na 3 V 2 (O 4 ) 2 F 3 / C was about 1.3 g / cm 3 , measured using a volumeter sold under the trade name STAV II by the company J . Engelsmann AG with the following parameters: volume of 250 ml (ISO 787) and 1250 shots.
  • a composite material B of formula Na 3 V 2 (O 4 ) 2 F 3 / C was prepared from a VPO 4 / C obtained according to the method of Barker et al. [US2002 / 0192553, carbothermy reduction, Example 1 (a)].
  • the composite material B of formula Na 3 V 2 (PO 4 ) 2 F 3 / C was prepared from this VPO 4 / C according to the same procedure as that described to produce the composite material 3.
  • the composite material 3 was analyzed from the point of view of its electrochemical performance and compared to the composite material B.
  • electrochemical tests were performed using cells of type button-cell ® .
  • the electrodes in the form of a film were made in air from formulated inks comprising 87.1% by weight of active material (ie composite material 3 or B), 7.7% by weight of carbon and 5.2% by weight of PVdF.
  • the button cells were assembled in a glove box.
  • an electrode film comprising the active material (i.e. composite material 3 or B), as a positive electrode,
  • FIG. 5 shows the curve of the potential vs Na (in volts) as a function of the capacity (in mAh / g) with a current regime of 1 Na exchanged per hour of the composite material B (FIG. 5a) and the composite material 3 ( Figure 5b) and the capacitance curve (in mAh / g) as a function of the number of cycles of the composite material B ( Figure 5c) and the composite material 3 ( Figure 5d).
  • FIG. 5 clearly shows a good stability of the cycle when the active material is prepared from the composite material obtained according to the method of the invention.
  • VPO 4 VPO 4 as obtained in Example 1 were mixed with 1.59 g of Na 3 PO 4 for 12 h using a Turbula-type space mixer comprising a bead. Then, the resulting mixture was heated at 810 ° C for 1 h in a quartz tube under an argon atmosphere. The tube was then cooled to room temperature using water.
  • the composite material 4 of formula Na 3 V 2 (PO 4 ) 3 / C obtained in the form of a powder was analyzed by X-ray diffraction (XRD) using an apparatus as described in FIG. example 1. The samples were scanned between 16 and 50 ° 2 ⁇ .
  • FIG. 6 represents an X-ray diffraction diagram of the composite material 4 of formula Na 3 V 2 (PO 4 ) 3 / C, as well as a TEM image of said composite material 4.
  • a composite material C of formula Na 3 V 2 (PO 4 ) 3 / C was prepared from a VPO 4 / C obtained according to the method of Barker et al. [US2002 / 0192553, carbothermy reduction, Example 1 (a)].
  • VP0 4 / C was therefore prepared according to a method identical to that described in Example 4.1 above, and then the composite material C of formula Na 3 V 2 (PO 4 ) 3 was prepared from this VP0 4 / C according to the same procedure as that described to produce the composite material 4.
  • the composite material 4 was analyzed from the point of view of its electrochemical performance and compared to the composite material C.
  • electrochemical tests were performed using cells of type button-cell ® .
  • the electrodes in the form of a film were made in air from formulated inks comprising 85.5% (respectively 80%) by mass of composite material 4 (respectively by mass of composite material C), 9, 8% by weight of carbon (respectively 14.2%) by mass of carbon and 4.7% (respectively 5.8%) by mass of PVdF.
  • the button cells were assembled in a glove box.
  • an electrode film comprising the active material (i.e. composite material 4 or C), as a positive electrode,
  • FIG. 7 shows the curve of the potential vs Na (in volts) as a function of the capacity (in mAh / g) with a current regime of C / 10 of the composite material C (FIG. 5a) and of the composite material 4 (FIG. ) and the capacitance curve (in mAh / g) as a function of the number of cycles of the composite material C (FIG. 5c) and of the composite material 4 (FIG. 5d).
  • FIG. 7 clearly shows a good stability of the cycling when the active material is prepared from the composite material obtained according to the method of the invention.
  • the tube was then cooled to room temperature using water.
  • the composite material of formula LiV (PO 4 ) F / C obtained in the form of a powder was analyzed by X-ray diffraction (XRD) using an apparatus as described in Example 1. The samples were scanned between 16 and 50 ° 2 ⁇ .
  • FIG. 8 represents an X-ray diffraction pattern of the composite material of formula LiV (P0 4 ) F / C, as well as a TEM image of said composite material 5.
  • a composite material D of formula LiV (PO 4 ) F / C was prepared from a VPO 4 / C obtained according to the method of Barker et al. [US2002 / 0192553, carbothermy reduction, Example 1 (a)].
  • VP0 4 / C was therefore prepared according to a method identical to that described in Example 4.1 above, then the composite material D of formula LiV (P0 4) F / C was prepared from this VP0 4 / C according to the same procedure as that described for producing the composite material 5.
  • the composite material 5 was analyzed from the point of view of its electrochemical performance and compared to the composite material D.
  • electrochemical tests were performed using cells of type button-cell ® .
  • the electrodes in the form of a film were made in air from formulated inks comprising 86.5% (respectively 87.1%) by mass of composite material 5 (respectively by mass of composite material D), 8.7% by weight of carbon (respectively 7.7%) by mass of carbon and 4.8% (respectively 5.2%) by mass of PVdF.
  • the button cells were assembled in a glove box.
  • an electrode film comprising the active material (i.e. composite material 5 or C), as a positive electrode,
  • FIG. 9 shows the curve of the potential vs Li (in volts) as a function of the capacity (in mAh / g) with a current regime of C of the composite material D (FIG. 9a) and of the composite material 5 (FIG. 9b) and the capacitance curve (in mAh / g) as a function of the number of cycles of the composite material D (FIG. 9c) and of the composite material 5 (FIG. 9d).
  • FIG. 9 clearly shows a good stability of the cycling when the active material is prepared from the composite material obtained according to the method of the invention.
  • V 2 O 5 vanadium oxide
  • H 3 PO 4 phosphoric acid
  • the resulting mixture was heated at 80 ° C with magnetic stirring for 12h to evaporate the water.
  • the residue obtained was heated at 890 ° C. for 1 h in a quartz tube under an argon atmosphere.
  • the tube was then cooled to room temperature using water.
  • the use of the agar-agar makes it possible at the same time to overcome the evolution of gas generated by the decomposition of the compound comprising at least one carboxylic acid function (compound Ai) and the carbon precursor (compound B) if it exists.
  • compound Ai carboxylic acid function
  • compound B carbon precursor
  • FIG. 10 10a: residue obtained during the temperature rise in Examples 1 and 2; 10b: residue obtained during the rise in temperature in Example 5).
  • the composite material 6 obtained in the form of a powder was analyzed by X-ray diffraction (XRD) using an apparatus as described in Example 1. The samples were scanned between 16 and 50 ° 2 ⁇ .
  • the X-ray diffraction pattern of the composite material 6 of the formula VP0 4 / C was similar to that obtained for the composite material of Example 1 (see FIG.
  • the TEM image of the composite material 6 of the formula VP0 4 / C was similar to that obtained for the composite material of Example 1 (see FIG.
  • the amount of carbon in the composite material 6 of formula VPO 4 / C was analyzed by ATG as in Example 1. It was about 5% by weight, based on the total mass of material.
  • V 2 O 5 vanadium oxide
  • H 3 PO 4 phosphoric acid
  • citric acid citric acid
  • 0.8 g of agar-agar were added. mixed in a beaker with 30 ml of distilled water.
  • the resulting mixture was heated at 85 ° C with magnetic stirring for 12h to evaporate the water.
  • the residue obtained was heated at 890 ° C. for 1 h in a quartz tube under an argon atmosphere.
  • the tube was then cooled to room temperature using water.
  • the composite material 7 obtained in the form of a powder was analyzed by X-ray diffraction (XRD) using an apparatus as described in Example 1. The samples were scanned between 16 and 50 ° 2 ⁇ .
  • the x-ray diffraction pattern of the composite material 7 of the formula VP0 4 / C was similar to that obtained for the composite material of Example 1 (see FIG.
  • the amount of carbon in the composite material 7 of formula VPO 4 / C was analyzed by ATG as in Example 1. It was about 5% by weight, based on the total mass of composite material.

Abstract

The invention relates to a process for preparing a vanadium phosphate-carbon composite material, to a vanadium phosphate-carbon composite material obtained according to said process, and also to the uses of said composite material, in particular as precursor for the synthesis of electrochemically active electrode materials or as active anode material.

Description

PROCÉDÉ DE PRÉPARATION D'UN MATÉRIAU COMPOSITE PHOSPHATE DE VANADIUM-CARBONE PAR VOIE LIQUIDE PROCESS FOR THE PREPARATION OF VANADIUM-CARBON COMPOSITE PHONYPHATE COMPOSITE BY LIQUID
L'invention concerne un procédé de préparation d'un matériau composite phosphate de vanadium-carbone, un matériau composite phosphate de vanadium-carbone obtenu selon ledit procédé, ainsi que les utilisations dudit matériau composite, notamment comme précurseur pour la synthèse de matériaux électrochimiquement actifs d'électrode ou comme matériau actif d'anode. The invention relates to a process for the preparation of a vanadium-carbon phosphate composite material, a vanadium-carbon phosphate composite material obtained according to the method, and to the uses of said composite material, especially as a precursor for the synthesis of electrochemically active materials. electrode or active anode material.
Elle s'applique en particulier au domaine des batteries lithium-ion ou sodium-ion, dans lequel il existe une demande croissante en matériaux actifs d'électrodes qui peuvent être obtenus selon un procédé simple et économique, tout en garantissant de bonnes performances électrochimiques.  It applies in particular to the field of lithium-ion or sodium-ion batteries, in which there is a growing demand for active electrode materials that can be obtained in a simple and economical process, while ensuring good electrochemical performance.
Une batterie au lithium (respectivement une batterie au sodium) comprend au moins une électrode négative et au moins une électrode positive entre lesquelles est placé un électrolyte solide ou un séparateur imprégné par un électrolyte liquide. L'électrolyte liquide est par exemple constitué d'un sel de lithium (respectivement d'un sel de sodium) en solution dans un solvant choisi pour optimiser le transport et la dissociation des ions. L'électrode positive est constituée par un collecteur de courant supportant un matériau d'électrode qui contient au moins une matière active d'électrode positive capable d'insérer des ions lithium (respectivement des ions sodium) de manière réversible ; l'électrode négative est constituée par une feuille de lithium (respectivement de sodium) métallique (éventuellement supportée par un collecteur de courant), d'un alliage de lithium (respectivement de sodium) ou d'un composé intermétallique de lithium (respectivement de sodium) (batterie au lithium) (respectivement batterie au sodium), ou par un collecteur de courant supportant un matériau d'électrode qui contient au moins une matière active d'électrode négative capable d'insérer des ions lithium (respectivement des ions sodium) de manière réversible (batterie aux ions lithium : Li-ion) (respectivement aux ions sodium : Na-ion). Chaque matériau d'électrode comprend généralement en outre un polymère qui joue le rôle de liant (e.g. poly(fluorure de vinylidène) ou PVdF) et/ou un agent conférant une conductivité électronique (e.g . carbone) et/ou un composé conférant une conduction ionique (e.g . sel de lithium) (e.g . respectivement sel de sodium). A lithium battery (respectively a sodium battery) comprises at least one negative electrode and at least one positive electrode between which is placed a solid electrolyte or a separator impregnated with a liquid electrolyte. For example, the liquid electrolyte consists of a lithium salt (or a sodium salt) dissolved in a solvent chosen to optimize the transport and dissociation of the ions. The positive electrode is constituted by a current collector supporting an electrode material which contains at least one positive electrode active material capable of inserting lithium ions (respectively sodium ions) in a reversible manner; the negative electrode consists of a sheet of lithium (respectively sodium) metal (optionally supported by a current collector), a lithium alloy (respectively sodium) or an intermetallic lithium compound (respectively sodium) ) (lithium battery) (respectively sodium battery), or by a current collector supporting an electrode material which contains at least one negative electrode active material capable of inserting lithium ions (respectively sodium ions) of reversible way (lithium ion battery: Li-ion) (respectively to sodium ions: Na-ion). Each electrode material generally further comprises a polymer which acts as a binder (eg polyvinylidene fluoride or PVdF) and / or a conferring agent. electronic conductivity (eg carbon) and / or an ionically conductive compound (eg lithium salt) (eg sodium salt).
Au cours du fonctionnement de la batterie, des ions lithium (respectivement des ions sodium) passent de l'une à l'autre des électrodes à travers l'électrolyte. Lors de la décharge de la batterie, une quantité de lithium (respectivement de sodium) réagit avec la matière active d'électrode positive à partir de l'électrolyte, et une quantité équivalente est introduite dans l'électrolyte à partir de la matière active de l'électrode négative, la concentration en lithium (respectivement en sodium) restant ainsi constante dans l'électrolyte. L'insertion du lithium (respectivement du sodium) dans l'électrode positive est compensée par apport d'électrons à partir de l'électrode négative via un circuit extérieur. Lors de la charge, les phénomènes inverses ont lieu. During operation of the battery, lithium ions (respectively sodium ions) pass from one to the other of the electrodes through the electrolyte. During discharge of the battery, a quantity of lithium (respectively sodium) reacts with the positive electrode active material from the electrolyte, and an equivalent amount is introduced into the electrolyte from the active ingredient of the negative electrode, the concentration of lithium (respectively sodium) thus remaining constant in the electrolyte. The insertion of lithium (respectively sodium) into the positive electrode is compensated by supplying electrons from the negative electrode via an external circuit. During charging, the reverse phenomena take place.
Plusieurs procédés sont connus pour préparer un matériau à base de phosphate de vanadium et de carbone. À titre d'exemple, Zhang et al. [J. Alloys and Compounds, 2012, 522, 167-171] ont décrit un procédé sol-gel pour former un matériau composite comprenant du phosphate de vanadium revêtu d'un film de carbone amorphe d'épaisseur 8 nm environ. Plus particulièrement, V205 et de l'acide oxalique en quantités stœchiométriques sont dissous dans de l'eau sous agitation pendant 1 h à 70°C. Puis, NH4H2P04 en quantités stœchiométriques est ajouté au mélange précédent à 70°C et le mélange résultant est maintenu à 70°C pendant 4h jusqu'à la formation d'un gel . Le gel obtenu est ensuite séché à 100°C pendant 12h, pour former une poudre qui est pressée sous la forme de pastilles. Les pastilles sont alors chauffées à 350°C pendant 4h sous argon et du glucose à titre de source de carbone est broyé avec les pastilles. Le mélange résultant est enfin calciné à 750°C pendant 12h sous argon. Toutefois, ce type de procédé comprend un grand nombre d'étapes et reste très long. Par ailleurs, l'étape de broyage intime entre le précurseur de phosphate de vanadium et le glucose est déterminante pour obtenir un revêtement de carbone homogène. Enfin, ce procédé met en œuvre du NH4H2P04 qui produit de l'ammoniac, le rendant difficilement industrialisable. Par ailleurs, Barker et al. ont décrit dans US2002/0192553 la réduction par carbothermie de V205 en présence de NH4H2P04 et de noir d'acétylène à 300°C pendant 3h sous air, le refroidissement du mélange résultant, son broyage, puis sa calcination à 750°C pendant 8h sous argon. L'utilisation de carbone en excès permet de conduire à un matériau comprenant du phosphate de vanadium et du carbone. Toutefois, le matériau se présente sous la forme de grains micrométriques de carbone mélangés à des grains micrométriques de phosphate de vanadium. Il présente donc des performances électrochimiques qui ne sont pas optimisées (cf. exemple 4 tel que décrit ci-après). Une alternative à la réduction par carbothermie est l'utilisation de dihydrogène à titre d'agent réducteur. En particulier, un mélange de V205 et de NH4H2P04 est chauffé à 300°C pendant 8h sous dihydrogène, refroidi, broyé, puis chauffé à 850°C pendant 8h sous dihydrogène. Toutefois, le phosphate de vanadium doit être ensuite mis en contact avec une source de carbone telle que du glucose lors d'une étape supplémentaire. Par ailleurs, NH4H2P04 libère du diazote sous atmosphère réductrice qui détériore les parois des appareils/réacteurs utilisés. Enfin, les étapes de broyage ou de mécanosynthèse utilisées dans les procédés précités sont coûteuses. Several methods are known for preparing a material based on vanadium phosphate and carbon. For example, Zhang et al. [J. Alloys and Compounds, 2012, 522, 167-171] have described a sol-gel process for forming a composite material comprising vanadium phosphate coated with an amorphous carbon film of about 8 nm thickness. More particularly, V 2 O 5 and oxalic acid in stoichiometric amounts are dissolved in water with stirring for 1 h at 70 ° C. Then, NH 4 H 2 PO 4 in stoichiometric amounts is added to the above mixture at 70 ° C and the resulting mixture is maintained at 70 ° C for 4h until a gel is formed. The gel obtained is then dried at 100 ° C. for 12 hours, to form a powder which is pressed in the form of pellets. The pellets are then heated at 350 ° C. for 4 hours under argon and glucose as a carbon source is ground with the pellets. The resulting mixture is finally calcined at 750 ° C. for 12 hours under argon. However, this type of process comprises a large number of steps and remains very long. Furthermore, the intimate grinding step between the vanadium phosphate precursor and the glucose is critical to obtain a homogeneous carbon coating. Finally, this process uses NH 4 H 2 PO 4 which produces ammonia, making it difficult to industrialize. In addition, Barker et al. described in US2002 / 0192553 the carbothermy reduction of V 2 0 5 in the presence of NH 4 H 2 PO 4 and acetylene black at 300 ° C for 3 h in air, the cooling of the resulting mixture, its grinding, then its calcination at 750 ° C for 8 hours under argon. The use of excess carbon leads to a material comprising vanadium phosphate and carbon. However, the material is in the form of micrometric grains of carbon mixed with micrometric vanadium phosphate grains. It therefore has electrochemical performances which are not optimized (see Example 4 as described below). An alternative to carbothermy reduction is the use of dihydrogen as a reducing agent. In particular, a mixture of V 2 O 5 and NH 4 H 2 PO 4 is heated at 300 ° C. for 8 h under dihydrogen, cooled, milled and then heated at 850 ° C. for 8 h under dihydrogen. However, the vanadium phosphate must then be contacted with a carbon source such as glucose in an additional step. Moreover, NH 4 H 2 PO 4 releases nitrous under a reducing atmosphere which deteriorates the walls of the appliances / reactors used. Finally, the grinding or mechanosynthesis steps used in the aforementioned methods are expensive.
La voie hydrothermale a également été proposée pour produire un matériau à base de phosphate de vanadium et éventuellement de carbone. Toutefois, cette voie requiert l'utilisation de très hautes pressions et/ou d'un autoclave qui augmentent le coût de production.  The hydrothermal route has also been proposed to produce a material based on vanadium phosphate and possibly carbon. However, this route requires the use of very high pressures and / or an autoclave that increase the cost of production.
Le but de la présente invention est par conséquent de pallier tout ou partie des inconvénients de l'art antérieur précité, et notamment de fournir un procédé simple (e.g . qui comporte peu d'étapes) et peu onéreux pour la préparation d'un matériau composite à base de phosphate de vanadium et de carbone, tout en évitant le dégagement de gaz nocifs tels que l'ammoniac.  The object of the present invention is therefore to overcome all or part of the disadvantages of the aforementioned prior art, and in particular to provide a simple method (eg which has few steps) and inexpensive for the preparation of a material composite based on vanadium phosphate and carbon, while avoiding the release of harmful gases such as ammonia.
L'invention a donc pour premier objet un procédé de préparation d'un matériau composite de phosphate de vanadium et de carbone répondant à la formule VP04/C, caractérisé en ce qu'il comprend les étapes suivantes : The invention therefore firstly relates to a method for preparing a vanadium and carbon phosphate composite material having the formula VP0 4 / C, characterized in that it comprises the following steps:
i) le mélange d'un précurseur de vanadium, H3P04, d'un composé A choisi parmi un composé comprenant au moins une fonction acide carboxylique (composé Ai) et un composé polysaccharide (composé A2), dans un solvant aqueux, étant entendu que lorsque le composé comprenant au moins une fonction acide carboxylique (composé Ai) est différent d'un précurseur de carbone, le mélange comprend en outre un composé précurseur de carbone (composé B), i) the mixture of a vanadium precursor, H 3 PO 4 , of a compound A selected from a compound comprising at least one carboxylic acid function (compound Ai) and a polysaccharide compound (compound A 2 ), in an aqueous solvent, it being understood that when the compound comprising at least one carboxylic acid function (compound Ai) is different from a precursor of carbon, the mixture further comprises a carbon precursor compound (compound B),
ii) le chauffage du mélange de l'étape i) à une température allant de 35°C à 100°C environ, afin de former un résidu solide, et  ii) heating the mixture of step i) at a temperature of about 35 ° C to 100 ° C, to form a solid residue, and
iii) le chauffage du résidu solide à une température supérieure à 850°C environ.  iii) heating the solid residue to a temperature above about 850 ° C.
Ainsi, le procédé de l'invention permet en peu d'étapes et de façon économique, de former directement un matériau composite de phosphate de vanadium et de carbone, tout en évitant le dégagement de gaz nocifs tels que l'ammoniac. Thus, the process of the invention allows in a few steps and economically, to directly form a composite material of vanadium phosphate and carbon, while avoiding the release of harmful gases such as ammonia.
L'étape i) est généralement effectuée à une température allant de 15 à Step i) is generally carried out at a temperature ranging from 15 to
30°, et de préférence de 20 à 25°C (i.e. température ambiante). 30 °, and preferably 20 to 25 ° C (i.e. ambient temperature).
Elle permet de former une suspension aqueuse comprenant le précurseur de vanadium, H3P04 (à titre de précurseur de phosphate), le composé A choisi parmi le composé comprenant au moins une fonction acide carboxylique et le composé polysaccharide, et éventuellement le composé précurseur de carbone. It makes it possible to form an aqueous suspension comprising the vanadium precursor, H 3 PO 4 (as phosphate precursor), the compound A chosen from the compound comprising at least one carboxylic acid function and the polysaccharide compound, and optionally the precursor compound of carbon.
Le solvant aqueux est de préférence de l'eau, notamment de l'eau distillée.  The aqueous solvent is preferably water, especially distilled water.
Le précurseur de vanadium est de préférence V205. The vanadium precursor is preferably V 2 0 5 .
Le rapport molaire [H3P04/élément vanadium dans le précurseur de vanadium] varie généralement de 1 à 1,5 environ. The molar ratio [H 3 PO 4 / vanadium element in the vanadium precursor] generally varies from about 1 to 1.5.
La concentration massique de précurseur de vanadium (e.g. V205) dans la suspension aqueuse à l'issue de l'étape i) varie de 0, 1% à 25% en masse environ, et de préférence de 0,5 à 15% en masse environ. Dans le procédé, le composé comprenant au moins une fonction acide carboxylique (composé Ai) joue le rôle d'agent chélatant. Par ailleurs, le composé Ai ou le composé précurseur de carbone (composé B) va permettre de former une couche de carbone enveloppant les particules de VP04. The mass concentration of vanadium precursor (eg V 2 0 5 ) in the aqueous suspension at the end of step i) ranges from about 0.1% to about 25% by weight, and preferably from 0.5 to 15% by weight. % by mass approximately. In the process, the compound comprising at least one carboxylic acid function (compound Ai) acts as a chelating agent. Moreover, the compound Al or the precursor compound of carbon (compound B) will make it possible to form a layer of carbon enveloping the particles of VP0 4 .
Le composé comprenant au moins une fonction acide carboxylique The compound comprising at least one carboxylic acid function
(composé Ai) peut être identique ou différent d'un précurseur de carbone. Lorsque le composé comprenant au moins une fonction acide carboxylique (composé Ai) est également un précurseur de carbone, il joue à la fois le rôle d'agent chélatant et de précurseur de carbone. L'ajout d'un composé précurseur de carbone n'est donc pas nécessaire. Lorsque le composé comprenant au moins une fonction acide carboxylique (composé Ai) n'est pas un précurseur de carbone, un composé précurseur de carbone (composé B) doit être utilisé. (compound Ai) may be the same as or different from a carbon precursor. When the compound comprising at least one carboxylic acid function (compound Ai) is also a precursor of carbon, it plays both the role of chelating agent and precursor of carbon. The addition of a precursor compound of carbon is therefore not necessary. When the compound comprising at least one carboxylic acid function (compound Ai) is not a precursor of carbon, a carbon precursor compound (compound B) must be used.
Dans le procédé, le composé polysaccharide (composé A2) présente l'avantage de jouer à la fois le rôle d'agent chélatant et de précurseur de carbone. In the process, the polysaccharide compound (compound A 2 ) has the advantage of acting as both a chelating agent and a precursor of carbon.
Selon une forme de réalisation particulièrement préférée de l'invention, le composé comprenant au moins une fonction acide carboxylique (composé Ai) est un acide polycarboxylique, et de préférence encore il comprend deux ou trois fonctions acide carboxylique.  According to a particularly preferred embodiment of the invention, the compound comprising at least one carboxylic acid function (compound Ai) is a polycarboxylic acid, and more preferably it comprises two or three carboxylic acid functions.
Dans un mode de réalisation particulier, le composé comprenant au moins une fonction acide carboxylique (composé Ai) comprend de 2 à 10 atomes de carbone, et de préférence de 2 à 6 atomes de carbone.  In a particular embodiment, the compound comprising at least one carboxylic acid function (compound Ai) comprises from 2 to 10 carbon atoms, and preferably from 2 to 6 carbon atoms.
Le composé comprenant au moins une fonction carboxylique (composé Ai) peut contenir en outre une ou plusieurs fonctions hydroxyles, notamment en position a d'une fonction acide carboxylique.  The compound comprising at least one carboxylic function (compound Ai) may also contain one or more hydroxyl functional groups, especially in the α-position of a carboxylic acid function.
Le composé comprenant au moins une fonction acide carboxylique (composé Ai) peut être choisi parmi les acides carboxyliques ou polycarboxyliques saturés tels que l'acide oxalique, l'acide citrique, l'acide glycolique, l'acide lactique, l'acide tartrique, l'acide malique, l'acide succinique, l'acide glycolique, l'acide malonique, l'acide glutarique, l'acide adipique, l'acide isocitrique, l'acide oxalosuccinique, l'acide tricarballylique et les acides carboxyliques ou polycarboxyliques insaturés tels que l'acide maléique, l'acide fumarique et l'acide aconitique. The compound comprising at least one carboxylic acid function (compound Ai) may be chosen from saturated carboxylic or polycarboxylic acids such as oxalic acid, citric acid, glycolic acid, lactic acid, tartaric acid, malic acid, succinic acid, glycolic acid, malonic acid, glutaric acid, adipic acid, acid isocitric acid, oxalosuccinic acid, tricarballylic acid and unsaturated carboxylic or polycarboxylic acids such as maleic acid, fumaric acid and aconitic acid.
Les acides carboxyliques ou polycarboxyliques saturés sont préférés. Saturated carboxylic or polycarboxylic acids are preferred.
Le rapport molaire [composé comprenant au moins une fonction acide carboxylique (composé Ai)/élément vanadium dans le précurseur de vanadium] est généralement d'au moins 1, et varie de préférence de 1 à 2 environ, et de préférence encore de 1,02 à 1,5 environ. Cela permet ainsi d'optimiser les performances électrochimiques. The molar ratio [compound comprising at least one carboxylic acid function (compound Al) / vanadium element in the vanadium precursor] is generally at least 1, and preferably varies from 1 to about 2, and more preferably from 1, About 02 to 1.5. This makes it possible to optimize the electrochemical performances.
Le rapport molaire [composé polysaccharide (composé A2)/élément vanadium dans le précurseur de vanadium] est généralement d'au moins 0,01, et varie de préférence de 0,1 à 0,6 environ. Cela permet ainsi d'optimiser les performances électrochimiques. The molar ratio [polysaccharide compound (A 2 compound) / vanadium element in the vanadium precursor] is generally at least 0.01, and preferably ranges from about 0.1 to about 0.6. This makes it possible to optimize the electrochemical performances.
Le composé précurseur de carbone (composé B) peut être un polyol tel qu'un diol ou un triol .  The carbon precursor compound (compound B) may be a polyol such as a diol or a triol.
Selon une forme de réalisation particulièrement préférée de l'invention, le composé précurseur de carbone (composé B) est choisi parmi l'éthylène glycol et le glycérol .  According to a particularly preferred embodiment of the invention, the carbon precursor compound (compound B) is chosen from ethylene glycol and glycerol.
Le rapport molaire [composé précurseur de carbone (composé B)/élément vanadium dans le précurseur de vanadium] varie de préférence de 0,05 à 2 environ, et de préférence encore de 0,25 à 0,45 environ.  The molar ratio [carbon precursor compound (compound B) / vanadium element in the vanadium precursor] preferably varies from 0.05 to 2 approximately, and more preferably from 0.25 to 0.45 approximately.
Le composé polysaccharide (composé A2) peut être choisi parmi les polysaccharides comprenant de l'agarose et/ou de l'agaropectine et les carraghénates. The polysaccharide compound (compound A 2 ) may be chosen from polysaccharides comprising agarose and / or agaropectin and carrageenates.
Selon une forme de réalisation particulièrement préférée de l'invention, le composé polysaccharide (composé A2) est un polysaccharide comprenant de l'agarose et/ou de l'agaropectine tel que l'agar-agar. According to a particularly preferred embodiment of the invention, the polysaccharide compound (compound A 2 ) is a polysaccharide comprising agarose and / or agaropectin such as agar-agar.
Selon une forme de réalisation particulièrement préférée de l'invention, le mélange de l'étape i) comprend soit de l'acide citrique (à titre de composé comprenant au moins une fonction acide carboxylique), soit de l'acide oxalique (à titre de composé comprenant au moins une fonction acide carboxylique) et de l'éthylène glycol ou du glycérol (à titre de composé précurseur de carbone), soit de l'agar-agar (à titre de composé polysaccharide). According to a particularly preferred embodiment of the invention, the mixture of step i) comprises either citric acid (as a compound comprising at least one carboxylic acid function) or oxalic acid. (as a compound comprising at least one carboxylic acid function) and ethylene glycol or glycerol (as a precursor compound for carbon), or agar agar (as polysaccharide compound).
L'étape i) dure généralement de 1 à 60 min environ. L'étape i) est de préférence un mélange mécanique.  Step i) generally lasts from about 1 to 60 minutes. Step i) is preferably a mechanical mixture.
Le mélange de l'étape i) peut comprendre en outre un polyol tel qu'un diol ou un triol, notamment lorsque le composé A est un composé comprenant au moins une fonction acide carboxylique (composé Ai) qui est un précurseur de carbone, ou un composé polysaccharide (composé A2). The mixture of step i) may further comprise a polyol such as a diol or a triol, especially when the compound A is a compound comprising at least one carboxylic acid function (compound Ai) which is a precursor of carbon, or a polysaccharide compound (compound A 2 ).
Le polyol peut être choisi parmi l'éthylène glycol et le glycérol .  The polyol may be chosen from ethylene glycol and glycerol.
Le mélange de l'étape i) peut comprendre en outre un liant.  The mixture of step i) may further comprise a binder.
Le liant peut permettre d'éviter la prise de volume lors de la mise en œuvre du procédé de l'invention, et ainsi peut permettre de figer le système, le rendant facilement industrialisable.  The binder can make it possible to avoid the increase of volume during the implementation of the process of the invention, and thus can freeze the system, making it easily industrializable.
Le liant peut être choisi parmi les polymères synthétiques tels que l'alcool polyvinylique, le polyéthylèneglycol, la polyvinylpyrrolidone, le polyacrylonitrile, le polyformaldéhyde, l'acide polylactique ou les polyitaconates ; les biopolymères tels que les polysaccharides, les dérivés de polysaccharides ou les polypeptides ; et un de leurs mélanges.  The binder may be chosen from synthetic polymers such as polyvinyl alcohol, polyethylene glycol, polyvinylpyrrolidone, polyacrylonitrile, polyformaldehyde, polylactic acid or polyitaconates; biopolymers such as polysaccharides, polysaccharide derivatives or polypeptides; and one of their mixtures.
À titre d'exemple de polysaccharides, on peut en particulier citer l'agar-agar, notamment lorsque le composé Ai est utilisé. Lorsqu'un liant est utilisé, la proportion de liant dans le mélange solide de l'étape i) varie de préférence de 0% à 50% environ en masse, et de préférence encore de 10% à 30% en masse environ. Le mélange solide ne tient pas compte du solvant aqueux. Il comprend donc le précurseur de vanadium, H3P04, le composé Ai ou A2, et le composé B s'il existe. As an example of polysaccharides, mention may in particular be made agar-agar, especially when the compound Ai is used. When a binder is used, the proportion of binder in the solid mixture of step i) preferably ranges from about 0% to about 50% by weight, and more preferably from about 10% to about 30% by weight. The solid mixture does not take into account the aqueous solvent. It therefore comprises the vanadium precursor, H 3 PO 4 , the compound A 1 or A 2 , and the compound B if it exists.
Au-delà d'une proportion de 50%, les performances électrochimiques sont réduites, notamment de par une diminution de la conductivité ionique et/ou de la densité d'énergie massique. L'étape ii) permet d'évaporer le solvant aqueux pour former un résidu solide. Above a proportion of 50%, the electrochemical performances are reduced, in particular by a decrease in the ionic conductivity and / or the specific energy density. Step ii) makes it possible to evaporate the aqueous solvent to form a solid residue.
L'étape ii) est généralement conduite sous air, notamment à l'aide d'une plaque chauffante.  Step ii) is generally conducted under air, in particular using a hot plate.
Dans un mode de réalisation particulier, l'étape ii) dure d'ih à 12h environ.  In a particular embodiment, step ii) lasts from 1h to 12h approximately.
L'étape ii) est de préférence effectuée sous agitation magnétique. Step ii) is preferably carried out with magnetic stirring.
Les étapes i) et ii) peuvent être concomitantes.  Steps i) and ii) can be concomitant.
L'étape iii) dure de préférence au moins 30 min environ, et de préférence encore au moins lh environ.  Step iii) preferably lasts at least about 30 minutes, and more preferably at least about 1 hour.
Dans un mode de réalisation particulier, l'étape iii) dure au plus 8h environ, de préférence au plus 5h environ, et de préférence encore au plus 3h environ.  In a particular embodiment, step iii) lasts not more than about 8 hours, preferably not more than about 5 hours, and more preferably not more than about 3 hours.
En effet, cette durée maximale permet d'éviter la formation de sous-produits tels que le phosphite de vanadium (VP).  Indeed, this maximum duration makes it possible to avoid the formation of by-products such as vanadium phosphite (VP).
L'étape iii) est de préférence conduite à une température supérieure à 860°C, de préférence encore comprise entre 870°C et 910°C environ, et de préférence encore comprise entre 880°C et 900°C environ.  Step iii) is preferably conducted at a temperature greater than 860 ° C, more preferably from about 870 ° C to 910 ° C, and more preferably from about 880 ° C to about 900 ° C.
L'étape iii) peut être mise en œuvre sous argon ou sous air.  Step iii) can be carried out under argon or under air.
L'étape iii) peut être mise en œuvre dans un contenant fermé ou ouvert.  Step iii) can be implemented in a closed or open container.
Le procédé peut comprendre en outre une étape iv) au cours de laquelle le matériau composite obtenu à l'issue de l'étape iii) est refroidi, notamment à la température ambiante (i.e. 20-25°C environ). The method may further comprise a step iv) in which the composite material obtained at the end of step iii) is cooled, especially at room temperature (i.e., about 20-25 ° C).
L'étape iv) peut être effectuée en utilisant de l'eau, et de préférence de l'eau froide (température de l'eau froide inférieure à la température ambiante, e.g . inférieure à 20-25°C environ).  Step iv) can be carried out using water, and preferably cold water (cold water temperature below room temperature, e.g. below about 20-25 ° C).
Le procédé ne comprend pas de préférence d'étape(s) de broyage et/ou de mécanosynthèse (bien connue sous l'anglicisme « bail milling »). Le procédé peut comprendre en outre étape ii') entre les étapes ii) et iii) au cours de laquelle le résidu solide est chauffé à une température de 200 à 400°C environ, en particulier pendant une durée de 30 minutes à 2h environ. Cette étape ii') peut être effectuée dans une étuve. The process does not preferably include grinding stage (s) and / or mechanosynthesis (well known under the term "lease milling"). The process may further comprise step ii ') between steps ii) and iii) during which the solid residue is heated to a temperature of about 200 to 400 ° C, in particular for a period of about 30 minutes to about 2 hours. This step ii ') can be carried out in an oven.
L'étape ii') peut permettre de contenir une éventuelle prise de volume en milieu ouvert.  Step ii ') may make it possible to contain a possible volume increase in an open environment.
Le procédé ne comprend pas de préférence d'autre(s) étape(s) de chauffage que les étapes ii), ii') et iii).  The method preferably does not include other heating step (s) than steps ii), ii ') and iii).
Le procédé ne comprend pas de préférence de mise en œuvre de pressions élevées (e.g. pressions de l'ordre de 3 bars) et/ou d'utilisation d'un autoclave.  The method preferably does not involve the implementation of high pressures (e.g. pressures of the order of 3 bars) and / or the use of an autoclave.
L'invention a pour deuxième objet un matériau composite de phosphate de vanadium et de carbone, caractérisé en ce qu'il est obtenu selon un procédé conforme au premier objet de l'invention.  The subject of the invention is a composite material of vanadium and carbon phosphate, characterized in that it is obtained according to a process according to the first subject of the invention.
En particulier, le matériau composite de l'invention comprend des particules de VP04 revêtues d'une couche de carbone amorphe. In particular, the composite material of the invention comprises particles of VP0 4 coated with an amorphous carbon layer.
Le matériau composite de phosphate de vanadium et de carbone de l'invention présente l'avantage de conduire à des matériaux électrochimiquement actifs d'électrodes qui présentent des performances électrochimiques améliorées par rapport à ceux obtenus à partir d'un matériau de phosphate de vanadium et de carbone de l'art antérieur.  The vanadium and carbon phosphate composite material of the invention has the advantage of leading to electrochemically active electrode materials which exhibit improved electrochemical performance over those obtained from a vanadium phosphate material and carbon of the prior art.
L'invention a donc pour troisième objet l'utilisation d'un matériau composite de phosphate de vanadium et de carbone tel qu'obtenu selon le procédé conforme au premier objet de l'invention comme précurseur pour la préparation de matériaux électrochimiquement actifs d'électrodes, et en particulier de matériaux actifs de cathodes de type polyanioniques tels que Na3V2(P04)2F3/C, Na3V2(P04)3/C ou LiVP04F/C. L'invention a pour quatrième objet l'utilisation d'un matériau composite de phosphate de vanadium et de carbone tel qu'obtenu selon le procédé conforme au premier objet de l'invention comme matériau actif d'anode. The invention therefore has for third object the use of a composite material of vanadium phosphate and carbon as obtained according to the process according to the first subject of the invention as a precursor for the preparation of electrochemically active electrode materials and in particular active materials of polyanionic type cathodes such as Na 3 V 2 (PO 4 ) 2 F 3 / C, Na 3 V 2 (PO 4 ) 3 / C or LiVPO 4 F / C. The fourth subject of the invention is the use of a composite material of vanadium and carbon phosphate as obtained according to the process according to the first subject of the invention as anode active material.
L'invention a pour cinquième objet un matériau composite de formule Na3V2( 04)2F3/C, caractérisé en ce qu'il est obtenu à partir d'un matériau composite de phosphate de vanadium et de carbone de formule VP04/C conforme au deuxième objet de l'invention ou obtenu selon un procédé conforme au premier objet de l'invention. The fifth subject of the invention is a composite material of the formula Na 3 V 2 (O 4 ) 2 F 3 / C, characterized in that it is obtained from a composite material of vanadium phosphate and of carbon of formula VPO 4 / C according to the second subject of the invention or obtained by a method according to the first subject of the invention.
Le matériau composite présente de préférence les paramètres de maille suivants : a = 9,0294(2) Â, b = 9,0445(2) Â, c = 10,7528(2) Â dans le système cristallin Amam. The composite material preferably has the following mesh parameters: a = 9.0294 (2) Å, b = 9.0445 (2) Å, c = 10.7528 (2) Å in the Amam crystalline system.
Le matériau composite Na3V2( 04)2F3/C de l'invention présente un rapport molaire Vanadium III/Vanadium IV supérieur à celui des matériaux composites de l'art antérieur. Cela permet ainsi d'obtenir des performances électrochimiques améliorées. Ce rapport molaire supérieur se traduit de préférence par un paramètre de maille c supérieur ou égale à 10,752 Â. The composite material Na 3 V 2 (O 4 ) 2 F 3 / C of the invention has a higher Vanadium III / Vanadium IV molar ratio than that of the composite materials of the prior art. This allows to obtain improved electrochemical performance. This upper molar ratio is preferably translated by a parameter of mesh c greater than or equal to 10.752 Å.
Par ailleurs, les inventeurs ont découvert de façon surprenante que le matériau composite Na3V2(P04)2F3/C de l'invention présente une densité tapée supérieure à celle des matériaux composites de l'art antérieur. La densité tapée est mesurée de préférence à l'aide d'un volunomètre, notamment un volunomètre vendu sous la dénomination commerciale STAV II par la société J . Engelsmann AG, avec de préférence les paramètres suivants : volume de 250 ml et 1250 coups. Moreover, the inventors have surprisingly discovered that the composite material Na 3 V 2 (PO 4 ) 2 F 3 / C of the invention has a higher typed density than the composite materials of the prior art. The density typed is preferably measured using a volumetric, including a volumeter sold under the trade name STAV II by the company J. Engelsmann AG, preferably with the following parameters: volume of 250 ml and 1250 strokes.
La densité tapée est obtenue selon les conditions de la Pharmacopée Européenne, des normes DIN ISO 787 Partie 11, ISO 3953, et ASTM B 527- 93.  The typed density is obtained according to the conditions of the European Pharmacopoeia, DIN ISO 787 Part 11, ISO 3953, and ASTM B 527-93.
La densité tapée du matériau composite Na3V2(P04)2F3/C de l'invention est de préférence supérieure à environ 0,5 g/cm3, et de préférence supérieure à environ 1 g/cm3. The typed density of the Na 3 V 2 (PO 4 ) 2 F 3 / C composite material of the invention is preferably greater than about 0.5 g / cm 3 , and preferably greater than about 1 g / cm 3 .
Selon une forme de réalisation particulièrement préférée de l'invention, la densité tapée du matériau composite Na3V2(P04)2F3/C varie d'environ 0,5 à 3,16 g/cm3, et de préférence encore d'environ 1 à 2 g/cm3. According to a particularly preferred embodiment of the invention, the typed density of the composite material Na 3 V 2 (PO 4 ) 2 F 3 / C varies from approximately 0.5 to 3.16 g / cm 3 , and more preferably about 1 to 2 g / cm 3 .
L'invention a pour sixième objet un matériau composite de formule Na3V2( 04)2F3/C, caractérisé en ce qu'il présente les paramètres de maille suivants : a = 9,0294(2) Â, b = 9,0445(2) Â, c = 10,7528(2) Â dans le système cristallin Amam. The subject of the invention is a composite material of formula Na 3 V 2 (O 4 ) 2 F 3 / C, characterized in that it has the following mesh parameters: a = 9.0294 (2) λ, b = 9 , 0445 (2) Å, c = 10.7528 (2) Å in the Amam crystalline system.
Ce matériau composite peut être obtenu à partir d'un matériau composite de phosphate de vanadium et de carbone de formule VP04/C conforme au deuxième objet de l'invention ou obtenu selon un procédé conforme au premier objet de l'invention. This composite material can be obtained from a composite material of vanadium phosphate and carbon of formula VP0 4 / C according to the second subject of the invention or obtained by a process according to the first subject of the invention.
EXEMPLES  EXAMPLES
Les matières premières utilisées dans les exemples, sont listées ci-après :  The raw materials used in the examples are listed below:
- H3P04, Alfa Aesar, 85% dans l'eau, - H 3 P0 4 , Alfa Aesar, 85% in water,
- V205, Alfa Aesar, 99,2%, V 2 0 5 , Alfa Aesar, 99.2%,
- acide citrique, Alfa Aesar, 99+%,  - citric acid, Alfa Aesar, 99 +%,
- acide oxalique, Sigma Aldrich, 98%,  oxalic acid, Sigma Aldrich, 98%,
- éthylène glycol, Fluka, >99,5%,  - ethylene glycol, Fluka,> 99.5%,
- agar-agar, Fisher BioReagents, BP2641-1  - agar-agar, Fisher BioReagents, BP2641-1
- Na3P04, Acros Organic, pure anhydre, Na 3 P0 4 , Acros Organic, pure anhydrous,
- NaF, Sigma Aldrich, >99%,  NaF, Sigma Aldrich,> 99%,
- eau distillée, et  - distilled water, and
- argon 5.0, Messer.  - argon 5.0, Messer.
Sauf indication spécifique, tous les matériaux ont été utilisés tels que reçus des fabricants.  Unless otherwise specified, all materials were used as received from manufacturers.
Exemple 1  Example 1
Préparation d'un matériau composite 1 de formule VP04/C selon le procédé conforme à l'invention Preparation of a Composite Material 1 of Formula VP0 4 / C According to the Process According to the Invention
4,04 g d'oxyde de vanadium (V205), 5,12 g d'acide phosphorique (H3P04), 4,2 g d'acide oxalique et 0,9 g d'éthylène glycol ont été mélangés dans un bêcher avec 20 ml d'eau distillée. Le mélange résultant a été chauffé à 85°C sous agitation magnétique pendant 12h afin d'évaporer l'eau. Le résidu obtenu a été chauffé à 890°C pendant lh dans un tube de quartz sous atmosphère d'argon. 4.04 g of vanadium oxide (V 2 O 5 ), 5.12 g of phosphoric acid (H 3 PO 4 ), 4.2 g of oxalic acid and 0.9 g of ethylene glycol were mixed in a beaker with 20 ml of distilled water. The resulting mixture was heated at 85 ° C with magnetic stirring for 12h to evaporate the water. The residue obtained was heated at 890 ° C. for 1 h in a quartz tube under an argon atmosphere.
Le tube a ensuite été refroidi jusqu'à la température ambiante en utilisant de l'eau.  The tube was then cooled to room temperature using water.
Le matériau composite 1 obtenu sous la forme d'une poudre a été analysé par diffraction aux rayons X (DRX) à l'aide d'un diffractomètre vendu sous la dénomination commerciale D8 par la société Bruker (radiation CuKa). Les échantillons ont été scannés entre 16 et 50° 2Θ.  The composite material 1 obtained in the form of a powder was analyzed by X-ray diffraction (XRD) using a diffractometer sold under the trade name D8 by Bruker (CuKa radiation). The samples were scanned between 16 and 50 ° 2Θ.
La figure 1 représente un diagramme de diffraction des rayons X du matériau composite 1 de formule VP04/C. FIG. 1 represents an X-ray diffraction pattern of the composite material 1 of the formula VP0 4 / C.
Tous les pics de diffraction de la figure 1 ont été indexés dans le système cristallin Cmcm avec les paramètres de maille suivants : a = 5,2399(4) Â, b = 7,7886(6) Â, et c = 6,2956(4) Â, ce qui est en accord avec la description donnée par Glaum et al. [Zeitschrift fuer Kristallographie (1979-2010), 1992, 198, 41-47] .  All the diffraction peaks of FIG. 1 were indexed in the Cmcm crystal system with the following mesh parameters: a = 5.2399 (4) Å, b = 7.7886 (6) Å, and c = 6.2956 (4), which is consistent with the description given by Glaum et al. [Zeitschrift fuer Kristallographie (1979-2010), 1992, 198, 41-47].
La quantité de carbone dans le matériau composite 1 de formule VP04/C a été analysée par analyse thermogravimétrique (ATG). Une vitesse de chauffe de 10°C par minute environ a été utilisée de 25°C à 680°C environ et un palier à 680°C pendant lh a été réalisé. La composition de la phase gazeuse a été contrôlée en parallèle du chauffage par spectroscopie de masse (MS). Elle était de 4,8% en masse environ, par rapport à la masse totale de matériau composite. The amount of carbon in the composite material 1 of the formula VP0 4 / C was analyzed by thermogravimetric analysis (TGA). A heating rate of about 10 ° C. per minute was used from about 25 ° C. to about 680 ° C. and a plateau at 680 ° C. for 1 hour was performed. The composition of the gas phase was monitored in parallel with mass spectroscopic (MS) heating. It was approximately 4.8% by weight, based on the total mass of composite material.
Le matériau composite 1 a également été analysé par microscopie électronique à transmission (MET) à l'aide d'un microscope vendu sous la dénomination commerciale FEI TECNAI G2 par la société FEI.  The composite material 1 was also analyzed by transmission electron microscopy (TEM) using a microscope sold under the trade name FEI TECNAI G2 by the company FEI.
La figure 2 représente une image par MET du matériau composite 1. Elle confirme la présence d'une coquille carbone d'épaisseur d'environ 5 nm, enveloppant le phosphate de vanadium. FIG. 2 represents a TEM image of the composite material 1. It confirms the presence of a carbon shell with a thickness of about 5 nm, enveloping the vanadium phosphate.
Exemple 2 Préparation d'un matériau composite 2 de formule VP04/C selon le procédé conforme à l'invention Example 2 Preparation of a composite material 2 of formula VP0 4 / C according to the process according to the invention
4,04 g d'oxyde de vanadium (V205), 5,12 g d'acide phosphorique (H3P04) et 5,6 g d'acide citrique ont été mélangés dans un bêcher avec 20 ml d'eau distillée. 4.04 g of vanadium oxide (V 2 O 5 ), 5.12 g of phosphoric acid (H 3 PO 4 ) and 5.6 g of citric acid were mixed in a beaker with 20 ml of distilled water.
Le mélange résultant a été chauffé à 85°C sous agitation magnétique pendant 12h afin d'évaporer l'eau. Le résidu obtenu a été chauffé à 890°C pendant lh dans un tube de quartz sous atmosphère d'argon.  The resulting mixture was heated at 85 ° C with magnetic stirring for 12h to evaporate the water. The residue obtained was heated at 890 ° C. for 1 h in a quartz tube under an argon atmosphere.
Le tube a ensuite été refroidi jusqu'à la température ambiante en utilisant de l'eau.  The tube was then cooled to room temperature using water.
Le matériau composite 2 obtenu sous la forme d'une poudre a été analysé par diffraction aux rayons X (DRX) à l'aide d'un appareil tel que décrit dans l'exemple 1. Les échantillons ont été scannés entre 16 et 50° 2Θ.  The composite material 2 obtained in the form of a powder was analyzed by X-ray diffraction (XRD) using an apparatus as described in Example 1. The samples were scanned between 16 and 50 ° 2Θ.
Le diagramme de diffraction des rayons X du matériau composite 2 de formule VP04/C était similaire à celui tel qu'obtenu pour le matériau composite de l'exemple 1 (cf. figure 1). The x-ray diffraction pattern of the composite material 2 of the formula VP0 4 / C was similar to that obtained for the composite material of Example 1 (see FIG.
L'image par MET du matériau composite 2 de formule VP04/C était similaire à celle telle qu'obtenue pour le matériau composite de l'exemple 1 (cf. figure 2). The TEM image of the composite material 2 of the formula VP0 4 / C was similar to that obtained for the composite material of Example 1 (see FIG.
La quantité de carbone dans le matériau composite 2 de formule The amount of carbon in the composite material 2 of formula
VP04/C a été analysée par ATG comme dans l'exemple 1. Elle était de 4,5% en masse environ, par rapport à la masse totale de matériau composite. VP0 4 / C was analyzed by ATG as in Example 1. It was 4.5% by weight approximately, based on the total mass of composite material.
Exemple 3 comparatif  Comparative Example 3
Préparation d'un matériau A selon un procédé non conforme à  Preparation of a material A according to a method which does not conform to
l'invention  the invention
4,04 g d'oxyde de vanadium (V205), 5,12 g d'acide phosphorique (H3P04), 4,2 g d'acide oxalique et 0,9 g d'éthylène glycol ont été mélangés dans un bêcher avec 20 ml d'eau distillée. 4.04 g of vanadium oxide (V 2 O 5 ), 5.12 g of phosphoric acid (H 3 PO 4 ), 4.2 g of oxalic acid and 0.9 g of ethylene glycol were mixed in a beaker with 20 ml of distilled water.
Le mélange résultant a été chauffé à 85°C sous agitation magnétique pendant 12h afin d'évaporer l'eau. Le résidu obtenu a été chauffé à 850°C pendant lOh dans un tube de quartz sous atmosphère d'argon. Le tube a ensuite été refroidi jusqu'à la température ambiante en utilisant de l'eau. The resulting mixture was heated at 85 ° C with magnetic stirring for 12h to evaporate the water. The resulting residue was heated at 850 ° C for 10 h in a quartz tube under an argon atmosphere. The tube was then cooled to room temperature using water.
Le matériau A obtenu sous la forme d'une poudre a été analysé par diffraction aux rayons X (DRX) à l'aide d'un appareil tel que décrit dans l'exemple 1. Les échantillons ont été scannés entre 20 et 40° 2Θ.  The material A obtained in the form of a powder was analyzed by X-ray diffraction (XRD) using an apparatus as described in Example 1. The samples were scanned between 20 and 40 ° 2Θ .
La figure 3 représente un diagramme de diffraction des rayons X du matériau A, montrant un matériau amorphe très différent des matériaux composites 1 et 2 respectivement obtenus dans les exemples 1 et 2.  FIG. 3 represents an X-ray diffraction pattern of material A, showing an amorphous material very different from composite materials 1 and 2 respectively obtained in Examples 1 and 2.
Exemple 4  Example 4
Utilisation d'un matériau composite de formule VP04/C obtenu selon un procédé conforme à l'invention comme précurseur pour la préparation de matériaux électrochimiquement actifs d'électrodes Use of a composite material of formula VP0 4 / C obtained according to a process according to the invention as a precursor for the preparation of electrochemically active electrode materials
4.1 Préparation de Na^f POjYy /C  4.1 Preparation of Na 2 PO 4 Y / C
4 g d'un matériau composite de formule VP04/C tel qu'obtenu dans l'exemple 1 ont été mélangés avec 1,22 g de NaF pendant 12h à l'aide d'un mélangeur spatial de type Turbula comprenant une bille. Puis, le mélange résultant a été chauffé à 700°C pendant lh dans un tube de quartz sous atmosphère d'argon. 4 g of a composite material of formula VP0 4 / C as obtained in Example 1 were mixed with 1.22 g of NaF for 12 hours using a Turbula-type space mixer comprising a bead. Then, the resulting mixture was heated at 700 ° C for 1 h in a quartz tube under an argon atmosphere.
Le tube a ensuite été refroidi jusqu'à la température ambiante en utilisant de l'eau.  The tube was then cooled to room temperature using water.
Le matériau composite 3 de formule Na3V2(P04)2F3/C obtenu sous la forme d'une poudre a été analysé par diffraction des rayons X (DRX) à l'aide d'un appareil tel que décrit dans l'exemple 1. Les échantillons ont été scannés entre 16 et 50° 2Θ. Le modèle de Rietveld a été utilisé pour affiner les paramètres de maille des matériaux. The composite material 3 of formula Na 3 V 2 (PO 4 ) 2 F 3 / C obtained in the form of a powder was analyzed by X-ray diffraction (XRD) using an apparatus as described in FIG. example 1. The samples were scanned between 16 and 50 ° 2Θ. The Rietveld model was used to refine the mesh parameters of the materials.
La figure 4 représente un diagramme de diffraction des rayons X du matériau composite 3 de formule Na3V2(P04)2F3/C, ainsi qu'une image par MET dudit matériau composite 3. FIG. 4 represents an X-ray diffraction pattern of the composite material 3 of formula Na 3 V 2 (PO 4 ) 2 F 3 / C, as well as a TEM image of said composite material 3.
Tous les pics de diffraction de la figure 4 ont été indexés dans le système cristallin Amam avec les paramètres de maille suivants : a = 9,0294(2) Â, b = 9,0445(2) Â, c = 10,7528(2) Â, ce qui est en accord avec la description donnée par Bianchini et al. [Chem. Mater. , 2015, 27, 8, 3009-3020] . All the diffraction peaks of FIG. 4 were indexed in the Amam crystal system with the following mesh parameters: a = 9.0294 (2) Å, b = 9.0445 (2) Å, c = 10.7528 ( 2) Â, which is in agreement with the description given by Bianchini et al. [Chem. Mater. , 2015, 27, 8, 3009-3020].
La densité tapée du matériau composite Na3V2( 04)2F3/C était de d'environ 1,3 g/cm3, mesurée à l'aide d'un volunomètre vendu sous la dénomination commerciale STAV II par la société J . Engelsmann AG avec les paramètres suivants : volume de 250 ml (ISO 787) et 1250 coups. The typed density of the composite material Na 3 V 2 (O 4 ) 2 F 3 / C was about 1.3 g / cm 3 , measured using a volumeter sold under the trade name STAV II by the company J . Engelsmann AG with the following parameters: volume of 250 ml (ISO 787) and 1250 shots.
À titre comparatif, un matériau composite B de formule Na3V2( 04)2F3/C a été préparé à partir d'un VP04/C obtenu selon le procédé de Barker et al. [US2002/0192553, réduction par carbothermie, exemple 1(a)] . By way of comparison, a composite material B of formula Na 3 V 2 (O 4 ) 2 F 3 / C was prepared from a VPO 4 / C obtained according to the method of Barker et al. [US2002 / 0192553, carbothermy reduction, Example 1 (a)].
Pour ce faire, 5,40 g de V205, 6,83g de NH4H2P04 et 0,76 g de carboneTo do this, 5.40 g of V 2 0 5 , 6.83 g of NH 4 H 2 PO 4 and 0.76 g of carbon
SP ont été mélangés, broyés et transformés en granulés. Puis les granulés ont été chauffés dans un four sous air jusqu'à 300°C (montée en température de 2°C par minute) puis le chauffage a été maintenu à 300°C pendant 3h puis à 800°C pendant 8h. Le mélange résultant a été refroidi à température ambiante. Une poudre noire de VP04/C a ainsi été obtenue. Le matériau composite B de formule Na3V2(P04)2F3/C a été préparé à partir de ce VP04/C selon le même mode opératoire que celui décrit pour produire le matériau composite 3. SP were mixed, crushed and pelletized. Then the granules were heated in an oven under air up to 300 ° C (temperature rise of 2 ° C per minute) then the heating was maintained at 300 ° C for 3h and then at 800 ° C for 8h. The resulting mixture was cooled to room temperature. A black powder of VP0 4 / C was thus obtained. The composite material B of formula Na 3 V 2 (PO 4 ) 2 F 3 / C was prepared from this VPO 4 / C according to the same procedure as that described to produce the composite material 3.
Le matériau composite 3 a été analysé du point de vue de ses performances électrochimiques et comparé au matériau composite B.  The composite material 3 was analyzed from the point of view of its electrochemical performance and compared to the composite material B.
Pour ce faire, des tests électrochimiques ont été effectués en utilisant des cellules de type pile-bouton®. Les électrodes sous la forme d'un film ont été réalisées à l'air à partir d'encres formulées comprenant 87, 1% en masse de matériau actif (i.e. matériau composite 3 ou B), 7,7 % en masse de carbone et 5,2% en masse de PVdF. Les piles boutons-ont été assemblées en boîte à gants. La cellule électrochimique comprenait : To do this, electrochemical tests were performed using cells of type button-cell ® . The electrodes in the form of a film were made in air from formulated inks comprising 87.1% by weight of active material (ie composite material 3 or B), 7.7% by weight of carbon and 5.2% by weight of PVdF. The button cells were assembled in a glove box. The electrochemical cell included:
- un film d'électrode comprenant la matière active (i.e. matériau composite 3 ou B), à titre d'électrode positive,  an electrode film comprising the active material (i.e. composite material 3 or B), as a positive electrode,
- une feuille de sodium, à titre d'électrode négative, - des fibres de verre catégorie Whatman GF/D catégorie 1823070, à titre de séparateur intercalé entre les électrodes positive et négative, et a sodium sheet, as a negative electrode, - Whatman GF / D category 1823070 glass fibers, as a separator interposed between the positive and negative electrodes, and
- une solution comprenant un sel de sodium NaPF6 (1 mol/1 environ) dissous dans un mélange de carbonate d'éthylène/carbonate de diméthyle (ratio 1/1 en masse), et 3% en masse de carbonate de fluoroéthylène, à titre d'électrolyte liquide. a solution comprising a sodium salt NaPF 6 (approximately 1 mol / l) dissolved in a mixture of ethylene carbonate / dimethyl carbonate (ratio 1/1 by weight), and 3% by weight of fluoroethylene carbonate, to as a liquid electrolyte.
La figure 5 montre la courbe du potentiel vs Na (en volts) en fonction de la capacité (en mAh/g) avec un régime de courant de 1 Na échangé par heure du matériau composite B (figure 5a) et du matériau composite 3 (figure 5b) et la courbe de la capacité (en mAh/g) en fonction du nombre de cycles du matériau composite B (figure 5c) et du matériau composite 3 (figure 5d).  FIG. 5 shows the curve of the potential vs Na (in volts) as a function of the capacity (in mAh / g) with a current regime of 1 Na exchanged per hour of the composite material B (FIG. 5a) and the composite material 3 ( Figure 5b) and the capacitance curve (in mAh / g) as a function of the number of cycles of the composite material B (Figure 5c) and the composite material 3 (Figure 5d).
La figure 5 montre clairement une bonne stabilité du cyclage lorsque la matière active est préparée à partir du matériau composite obtenu selon le procédé de l'invention.  FIG. 5 clearly shows a good stability of the cycle when the active material is prepared from the composite material obtained according to the method of the invention.
4.2 Préparation de Na^f POjWC  4.2 Preparation of Na 2 POjWC
4 g de VP04 tel qu'obtenu dans l'exemple 1 ont été mélangés avec 1,59 g de Na3P04 pendant 12h à l'aide d'un mélangeur spatial de type Turbula comprenant une bille. Puis, le mélange résultant a été chauffé à 810°C pendant lh dans un tube de quartz sous atmosphère d'argon. Le tube a ensuite été refroidi jusqu'à la température ambiante en utilisant de l'eau. 4 g of VPO 4 as obtained in Example 1 were mixed with 1.59 g of Na 3 PO 4 for 12 h using a Turbula-type space mixer comprising a bead. Then, the resulting mixture was heated at 810 ° C for 1 h in a quartz tube under an argon atmosphere. The tube was then cooled to room temperature using water.
Le matériau composite 4 de formule Na3V2(P04)3/C obtenu sous la forme d'une poudre a été analysé par diffraction des rayons X (DRX) à l'aide d'un appareil tel que décrit dans l'exemple 1. Les échantillons ont été scannés entre 16 et 50° 2Θ. The composite material 4 of formula Na 3 V 2 (PO 4 ) 3 / C obtained in the form of a powder was analyzed by X-ray diffraction (XRD) using an apparatus as described in FIG. example 1. The samples were scanned between 16 and 50 ° 2Θ.
La figure 6 représente un diagramme de diffraction des rayons X du matériau composite 4 de formule Na3V2(P04)3/C, ainsi qu'une image par MET dudit matériau composite 4. FIG. 6 represents an X-ray diffraction diagram of the composite material 4 of formula Na 3 V 2 (PO 4 ) 3 / C, as well as a TEM image of said composite material 4.
Tous les pics de diffraction de la figure 6 ont été indexés dans le système cristallin R-3c avec les paramètres de maille suivants : a = 8,7217(2) Â, b = 8,7217(2) Â et c = 21,8485(7) Â, ce qui est en accord avec la description donnée par Zatovsky et al. [Acta Crystallographica, Section E., Structure Reports Online, 2010, 66, 2, pil2-pil2] . All the diffraction peaks of FIG. 6 were indexed in the R-3c crystal system with the following mesh parameters: a = 8.7217 (2) Å, b = 8.7217 (2) Å and c = 21.8485 (7) Å, which is consistent with the description given by Zatovsky et al. [Acta Crystallographica, Section E., Structure Reports Online, 2010, 66, 2, pil2-pil2].
À titre comparatif, un matériau composite C de formule Na3V2(P04)3/C a été préparé à partir d'un VP04/C obtenu selon le procédé de Barker et al. [US2002/0192553, réduction par carbothermie, exemple 1(a)] . Le VP04/C a donc été préparé selon un procédé identique à celui décrit dans l'exemple 4.1 ci-dessus, puis le matériau composite C de formule Na3V2(P04)3 a été préparé à partir de ce VP04/C selon le même mode opératoire que celui décrit pour produire le matériau composite 4. For comparison, a composite material C of formula Na 3 V 2 (PO 4 ) 3 / C was prepared from a VPO 4 / C obtained according to the method of Barker et al. [US2002 / 0192553, carbothermy reduction, Example 1 (a)]. VP0 4 / C was therefore prepared according to a method identical to that described in Example 4.1 above, and then the composite material C of formula Na 3 V 2 (PO 4 ) 3 was prepared from this VP0 4 / C according to the same procedure as that described to produce the composite material 4.
Le matériau composite 4 a été analysé du point de vue de ses performances électrochimiques et comparé au matériau composite C.  The composite material 4 was analyzed from the point of view of its electrochemical performance and compared to the composite material C.
Pour ce faire, des tests électrochimiques ont été effectués en utilisant des cellules de type pile-bouton®. Les électrodes sous la forme d'un film ont été réalisées à l'air à partir d'encres formulées comprenant 85,5% (respectivement 80%) en masse de matériau composite 4 (respectivement en masse de matériau composite C), 9,8 % en masse de carbone (respectivement 14,2%) en masse de carbone et 4,7% (respectivement 5,8%) en masse de PVdF. Les piles boutons ont été assemblées en boîte à gants. La cellule électrochimique comprenait : To do this, electrochemical tests were performed using cells of type button-cell ® . The electrodes in the form of a film were made in air from formulated inks comprising 85.5% (respectively 80%) by mass of composite material 4 (respectively by mass of composite material C), 9, 8% by weight of carbon (respectively 14.2%) by mass of carbon and 4.7% (respectively 5.8%) by mass of PVdF. The button cells were assembled in a glove box. The electrochemical cell included:
- un film d'électrode comprenant la matière active (i.e. matériau composite 4 ou C), à titre d'électrode positive,  an electrode film comprising the active material (i.e. composite material 4 or C), as a positive electrode,
- une feuille de sodium, à titre d'électrode négative,  a sodium sheet, as a negative electrode,
- des fibres de verre catégorie Whatman GF/D catégorie 1823070, à titre de séparateur intercalé entre les électrodes positive et négative, et  - Whatman GF / D category 1823070 glass fibers, as a separator interposed between the positive and negative electrodes, and
- une solution comprenant un sel de sodium NaPF6 (1 mol/1 environ) dissous dans un mélange de carbonate d'éthylène/carbonate de diméthyle (ratio 1/1 en masse), et 3% en masse de carbonate de fluoroéthylène, à titre d'électrolyte liquide. La figure 7 montre la courbe du potentiel vs Na (en volts) en fonction de la capacité (en mAh/g) avec un régime de courant de C/10 du matériau composite C (figure 5a) et du matériau composite 4 (figure 5b) et la courbe de la capacité (en mAh/g) en fonction du nombre de cycles du matériau composite C (figure 5c) et du matériau composite 4 (figure 5d). a solution comprising a sodium salt NaPF 6 (approximately 1 mol / l) dissolved in a mixture of ethylene carbonate / dimethyl carbonate (ratio 1/1 by weight), and 3% by weight of fluoroethylene carbonate, to as a liquid electrolyte. FIG. 7 shows the curve of the potential vs Na (in volts) as a function of the capacity (in mAh / g) with a current regime of C / 10 of the composite material C (FIG. 5a) and of the composite material 4 (FIG. ) and the capacitance curve (in mAh / g) as a function of the number of cycles of the composite material C (FIG. 5c) and of the composite material 4 (FIG. 5d).
La figure 7 montre clairement une bonne stabilité du cyclage lorsque la matière active est préparée à partir du matériau composite obtenu selon le procédé de l'invention.  FIG. 7 clearly shows a good stability of the cycling when the active material is prepared from the composite material obtained according to the method of the invention.
4.3 Préparation de LiVfPCV)F/C 4.3 Preparation of LiVfPCV) F / C
4 g de VP04 tel qu'obtenu dans l'exemple 1 ont été mélangés avec4 g of VPO 4 as obtained in Example 1 were mixed with
0,68 g de LiF pendant 12h à l'aide d'un mélangeur spatial de type Turbula comprenant une bille. Puis, le mélange résultant a été chauffé à 700°C pendant lh dans un tube de quartz sous atmosphère d'argon. 0.68 g of LiF for 12 hours using a Turbula-type space mixer comprising a bead. Then, the resulting mixture was heated at 700 ° C for 1 h in a quartz tube under an argon atmosphere.
Le tube a ensuite été refroidi jusqu'à la température ambiante en utilisant de l'eau. The tube was then cooled to room temperature using water.
Le matériau composite 5 de formule LiV(P04)F/C obtenu sous la forme d'une poudre a été analysé par diffraction des rayons X (DRX) à l'aide d'un appareil tel que décrit dans l'exemple 1. Les échantillons ont été scannés entre 16 et 50° 2Θ. The composite material of formula LiV (PO 4 ) F / C obtained in the form of a powder was analyzed by X-ray diffraction (XRD) using an apparatus as described in Example 1. The samples were scanned between 16 and 50 ° 2Θ.
La figure 8 représente un diagramme de diffraction des rayons X du matériau composite 5 de formule LiV(P04)F/C, ainsi qu'une image par MET dudit matériau composite 5. FIG. 8 represents an X-ray diffraction pattern of the composite material of formula LiV (P0 4 ) F / C, as well as a TEM image of said composite material 5.
Tous les pics de diffraction de la figure 8 ont été indexés dans le système cristallin P-l avec les paramètres de maille suivants : a = 5, 1751(5) Â, b = 5,3041(4) Â, c = 7,2481(6) Â, a = 107,507(4)°, β = 107,847(5) ° et y = 98,450(4)°, ce qui est en accord avec la description donnée par Ateba Mba et al. [Chemistry of Materials, 2012, 24, 6, 1223-1234] .  All the diffraction peaks of FIG. 8 were indexed in the crystalline system P1 with the following mesh parameters: a = 5, 1751 (5) Å, b = 5.3041 (4) Å, c = 7.2481 ( 6) λ = 107.507 (4) °, β = 107.847 (5) ° and y = 98.450 (4) °, which is consistent with the description given by Ateba Mba et al. [Chemistry of Materials, 2012, 24, 6, 1223-1234].
À titre comparatif, un matériau composite D de formule LiV(P04)F/C a été préparé à partir d'un VP04/C obtenu selon le procédé de Barker et al. [US2002/0192553, réduction par carbothermie, exemple 1(a)] . Le VP04/C a donc été préparé selon un procédé identique à celui décrit dans l'exemple 4.1 ci-dessus, puis le matériau composite D de formule LiV(P04)F/C a été préparé à partir de ce VP04/C selon le même mode opératoire que celui décrit pour produire le matériau composite 5. By way of comparison, a composite material D of formula LiV (PO 4 ) F / C was prepared from a VPO 4 / C obtained according to the method of Barker et al. [US2002 / 0192553, carbothermy reduction, Example 1 (a)]. VP0 4 / C was therefore prepared according to a method identical to that described in Example 4.1 above, then the composite material D of formula LiV (P0 4) F / C was prepared from this VP0 4 / C according to the same procedure as that described for producing the composite material 5.
Le matériau composite 5 a été analysé du point de vue de ses performances électrochimiques et comparé au matériau composite D.  The composite material 5 was analyzed from the point of view of its electrochemical performance and compared to the composite material D.
Pour ce faire, des tests électrochimiques ont été effectués en utilisant des cellules de type pile-bouton®. Les électrodes sous la forme d'un film ont été réalisées à l'air à partir d'encres formulées comprenant 86,5% (respectivement 87, 1%) en masse de matériau composite 5 (respectivement en masse de matériau composite D), 8,7% en masse de carbone (respectivement 7,7%) en masse de carbone et 4,8% (respectivement 5,2%) en masse de PVdF. Les piles boutons ont été assemblées en boîte à gants. La cellule électrochimique comprenait : To do this, electrochemical tests were performed using cells of type button-cell ® . The electrodes in the form of a film were made in air from formulated inks comprising 86.5% (respectively 87.1%) by mass of composite material 5 (respectively by mass of composite material D), 8.7% by weight of carbon (respectively 7.7%) by mass of carbon and 4.8% (respectively 5.2%) by mass of PVdF. The button cells were assembled in a glove box. The electrochemical cell included:
- un film d'électrode comprenant la matière active (i.e. matériau composite 5 ou C), à titre d'électrode positive,  an electrode film comprising the active material (i.e. composite material 5 or C), as a positive electrode,
- une feuille de lithium, à titre d'électrode négative,  a lithium sheet, as a negative electrode,
- des fibres de verre catégorie Whatman GF/D catégorie 1823070, à titre de séparateur intercalé entre les électrodes positive et négative, et  - Whatman GF / D category 1823070 glass fibers, as a separator interposed between the positive and negative electrodes, and
- une solution comprenant un sel de sodium LiPF6 (1 mol/1 environ) dissous dans un mélange de carbonate d'éthylène/carbonate de diméthylea solution comprising a sodium salt LiPF 6 (approximately 1 mol / l) dissolved in a mixture of ethylene carbonate / dimethyl carbonate
(ratio 1/1 en masse), et 3% en masse de carbonate de fluoroéthylène, à titre d'électrolyte liquide. (1/1 ratio by weight), and 3% by weight of fluoroethylene carbonate, as liquid electrolyte.
La figure 9 montre la courbe du potentiel vs Li (en volts) en fonction de la capacité (en mAh/g) avec un régime de courant de C du matériau composite D (figure 9a) et du matériau composite 5 (figure 9b) et la courbe de la capacité (en mAh/g) en fonction du nombre de cycles du matériau composite D (figure 9c) et du matériau composite 5 (figure 9d).  FIG. 9 shows the curve of the potential vs Li (in volts) as a function of the capacity (in mAh / g) with a current regime of C of the composite material D (FIG. 9a) and of the composite material 5 (FIG. 9b) and the capacitance curve (in mAh / g) as a function of the number of cycles of the composite material D (FIG. 9c) and of the composite material 5 (FIG. 9d).
La figure 9 montre clairement une bonne stabilité du cyclage lorsque la matière active est préparée à partir du matériau composite obtenu selon le procédé de l'invention. Exemple 5 FIG. 9 clearly shows a good stability of the cycling when the active material is prepared from the composite material obtained according to the method of the invention. Example 5
Préparation d'un matériau composite 6 de formule VP04/C selon le procédé conforme à l'invention Preparation of a composite material 6 of formula VP0 4 / C according to the process according to the invention
4,04 g d'oxyde de vanadium (V205), 5,12 g d'acide phosphorique (H3P04) et 2 g d'agar-agar dans un bêcher avec 50 ml d'eau distillée. 4.04 g of vanadium oxide (V 2 O 5 ), 5.12 g of phosphoric acid (H 3 PO 4 ) and 2 g of agar in a beaker with 50 ml of distilled water.
Le mélange résultant a été chauffé à 80°C sous agitation magnétique pendant 12h afin d'évaporer l'eau. Le résidu obtenu a été chauffé à 890°C pendant lh dans un tube de quartz sous atmosphère d'argon. The resulting mixture was heated at 80 ° C with magnetic stirring for 12h to evaporate the water. The residue obtained was heated at 890 ° C. for 1 h in a quartz tube under an argon atmosphere.
Le tube a ensuite été refroidi jusqu'à la température ambiante en utilisant de l'eau. The tube was then cooled to room temperature using water.
L'utilisation de l'agar-agar permet à la fois de s'affranchir du dégagement gazeux généré par la décomposition du composé comprenant au moins une fonction acide carboxylique (composé Ai) et du précurseur de carbone (composé B) s'il existe, utilisés dans les exemples 1 et 2 lorsqu'ils sont en contact avec l'acide phosphorique ; et de limiter l'expansion volumique du mélange observée lors de la montée en température jusqu'à 890°C comme le montre la figure 10 (10a : résidu obtenu lors de la montée en température dans les exemples 1 et 2 ; 10b : résidu obtenu lors de la montée en température dans l'exemple 5). Le matériau composite 6 obtenu sous la forme d'une poudre a été analysé par diffraction aux rayons X (DRX) à l'aide d'un appareil tel que décrit dans l'exemple 1. Les échantillons ont été scannés entre 16 et 50° 2Θ. The use of the agar-agar makes it possible at the same time to overcome the evolution of gas generated by the decomposition of the compound comprising at least one carboxylic acid function (compound Ai) and the carbon precursor (compound B) if it exists. used in Examples 1 and 2 when in contact with phosphoric acid; and to limit the volume expansion of the mixture observed during the rise in temperature to 890 ° C. as shown in FIG. 10 (10a: residue obtained during the temperature rise in Examples 1 and 2; 10b: residue obtained during the rise in temperature in Example 5). The composite material 6 obtained in the form of a powder was analyzed by X-ray diffraction (XRD) using an apparatus as described in Example 1. The samples were scanned between 16 and 50 ° 2Θ.
Le diagramme de diffraction des rayons X du matériau composite 6 de formule VP04/C était similaire à celui tel qu'obtenu pour le matériau composite de l'exemple 1 (cf. figure 1). The X-ray diffraction pattern of the composite material 6 of the formula VP0 4 / C was similar to that obtained for the composite material of Example 1 (see FIG.
L'image par MET du matériau composite 6 de formule VP04/C était similaire à celle telle qu'obtenue pour le matériau composite de l'exemple 1 (cf. figure 2). La quantité de carbone dans le matériau composite 6 de formule VP04/C a été analysée par ATG comme dans l'exemple 1. Elle était de 5% en masse environ, par rapport à la masse totale de matériau. The TEM image of the composite material 6 of the formula VP0 4 / C was similar to that obtained for the composite material of Example 1 (see FIG. The amount of carbon in the composite material 6 of formula VPO 4 / C was analyzed by ATG as in Example 1. It was about 5% by weight, based on the total mass of material.
Exemple 7  Example 7
Préparation d'un matériau composite 7 de formule VP04/C selon le procédé conforme à l'invention Preparation of a composite material 7 of formula VP0 4 / C according to the process according to the invention
4,04 g d'oxyde de vanadium (V205), 5,12 g d'acide phosphorique (H3P04), 5,4 g d'acide citrique et 0,8 g d'agar-agar ont été mélangés dans un bêcher avec 30 ml d'eau distillée. 4.04 g of vanadium oxide (V 2 O 5 ), 5.12 g of phosphoric acid (H 3 PO 4 ), 5.4 g of citric acid and 0.8 g of agar-agar were added. mixed in a beaker with 30 ml of distilled water.
Le mélange résultant a été chauffé à 85°C sous agitation magnétique pendant 12h afin d'évaporer l'eau. Le résidu obtenu a été chauffé à 890°C pendant lh dans un tube de quartz sous atmosphère d'argon.  The resulting mixture was heated at 85 ° C with magnetic stirring for 12h to evaporate the water. The residue obtained was heated at 890 ° C. for 1 h in a quartz tube under an argon atmosphere.
Le tube a ensuite été refroidi jusqu'à la température ambiante en utilisant de l'eau.  The tube was then cooled to room temperature using water.
Le matériau composite 7 obtenu sous la forme d'une poudre a été analysé par diffraction aux rayons X (DRX) à l'aide d'un appareil tel que décrit dans l'exemple 1. Les échantillons ont été scannés entre 16 et 50° 2Θ.  The composite material 7 obtained in the form of a powder was analyzed by X-ray diffraction (XRD) using an apparatus as described in Example 1. The samples were scanned between 16 and 50 ° 2Θ.
Le diagramme de diffraction des rayons X du matériau composite 7 de formule VP04/C était similaire à celui tel qu'obtenu pour le matériau composite de l'exemple 1 (cf. figure 1). The x-ray diffraction pattern of the composite material 7 of the formula VP0 4 / C was similar to that obtained for the composite material of Example 1 (see FIG.
L'image par MET du matériau composite 7 de formule VP04/C était similaire à celle telle qu'obtenue pour le matériau composite de l'exemple 1 (cf. figure 2). The TEM image of the composite material 7 of formula VP0 4 / C was similar to that obtained for the composite material of Example 1 (see FIG.
La quantité de carbone dans le matériau composite 7 de formule VP04/C a été analysée par ATG comme dans l'exemple 1. Elle était de 5% en masse environ, par rapport à la masse totale de matériau composite. The amount of carbon in the composite material 7 of formula VPO 4 / C was analyzed by ATG as in Example 1. It was about 5% by weight, based on the total mass of composite material.

Claims

REVENDICATIONS
1. Procédé de préparation d'un matériau composite de phosphate de vanadium et de carbone répondant à la formule VP04/C, caractérisé en ce qu'il comprend les étapes suivantes : 1. Process for the preparation of a composite material of vanadium phosphate and carbon corresponding to the formula VP0 4 / C, characterized in that it comprises the following steps:
i) le mélange d'un précurseur de vanadium, H3P04, d'un composé A choisi parmi un composé comprenant au moins une fonction acide carboxylique et un composé polysaccharide dans un solvant aqueux, étant entendu que lorsque le composé comprenant au moins une fonction acide carboxylique est différent d'un précurseur de carbone, le mélange comprend en outre un composé précurseur de carbone, i) the mixture of a vanadium precursor, H 3 PO 4 , of a compound A selected from a compound comprising at least one carboxylic acid function and a polysaccharide compound in an aqueous solvent, it being understood that when the compound comprising at least a carboxylic acid function is different from a carbon precursor, the mixture further comprises a carbon precursor compound,
ii) le chauffage du mélange de l'étape i) à une température allant de 35°C à 100°C, afin de former un résidu solide, et  ii) heating the mixture of step i) at a temperature of 35 ° C to 100 ° C, to form a solid residue, and
iii) le chauffage du résidu solide à une température supérieure à iii) heating the solid residue to a temperature greater than
850°C. 850 ° C.
2. Procédé selon la revendication 1, caractérisé en ce que le précurseur de vanadium est V205. 2. Method according to claim 1, characterized in that the vanadium precursor is V 2 0 5 .
3. Procédé selon la revendication 1 ou 2, caractérisé en ce que le composé comprenant au moins une fonction acide carboxylique comprend de 2 à 10 atomes de carbone.  3. Method according to claim 1 or 2, characterized in that the compound comprising at least one carboxylic acid function comprises from 2 to 10 carbon atoms.
4. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que le composé comprenant au moins une fonction acide carboxylique est un acide carboxylique ou polycarboxylique saturé choisi parmi l'acide oxalique, l'acide citrique, l'acide glycolique, l'acide lactique, l'acide tartrique, l'acide malique, l'acide succinique, l'acide glycolique, l'acide malonique, l'acide glutarique, l'acide adipique, l'acide isocitrique, l'acide oxalosuccinique et l'acide tricarballylique.  4. Method according to any one of the preceding claims, characterized in that the compound comprising at least one carboxylic acid function is a saturated carboxylic acid or polycarboxylic acid chosen from oxalic acid, citric acid, glycolic acid, lactic acid and the like. lactic acid, tartaric acid, malic acid, succinic acid, glycolic acid, malonic acid, glutaric acid, adipic acid, isocitric acid, oxalosuccinic acid and lactic acid. tricarballylic acid.
5. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que le rapport molaire [composé comprenant au moins une fonction acide carboxylique/élément vanadium dans le précurseur de vanadium] varie de 1 à 2. 5. Method according to any one of the preceding claims, characterized in that the molar ratio [compound comprising at least one carboxylic acid function / vanadium element in the vanadium precursor] varies from 1 to 2.
6. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que le composé précurseur de carbone est choisi parmi l'éthylène glycol et le glycérol . 6. Process according to any one of the preceding claims, characterized in that the carbon precursor compound is chosen from ethylene glycol and glycerol.
7. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que le rapport molaire [composé précurseur de carbone/élément vanadium dans le précurseur de vanadium] varie de 0,05 à 2.  7. Process according to any one of the preceding claims, characterized in that the molar ratio [carbon precursor compound / vanadium element in the vanadium precursor] varies from 0.05 to 2.
8. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que le composé polysaccharide est l'agar-agar.  8. Process according to any one of the preceding claims, characterized in that the polysaccharide compound is agar-agar.
9. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que le mélange de l'étape i) comprend :  9. Process according to any one of the preceding claims, characterized in that the mixture of stage i) comprises:
- soit de l'acide citrique,  - either citric acid,
- soit de l'acide oxalique et de l'éthylène glycol ou du glycérol,  either oxalic acid and ethylene glycol or glycerol,
- soit de l'agar-agar.  - or agar-agar.
10. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que le mélange de l'étape i) comprend en outre un liant.  10. Method according to any one of the preceding claims, characterized in that the mixture of step i) further comprises a binder.
11. Procédé selon la revendication 9, caractérisé en ce que le liant est l'agar-agar lorsque le composé comprenant au moins une fonction acide carboxylique est utilisé.  11. The method of claim 9, characterized in that the binder is agar-agar when the compound comprising at least one carboxylic acid function is used.
12. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que l'étape iii) dure au plus 8h.  12. Method according to any one of the preceding claims, characterized in that step iii) lasts at most 8h.
13. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que l'étape iii) est conduite à une température comprise entre 880°C et 900°C.  13. Process according to any one of the preceding claims, characterized in that step iii) is carried out at a temperature of between 880 ° C. and 900 ° C.
14. Matériau composite de phosphate de vanadium et de carbone, caractérisé en ce qu'il est obtenu selon un procédé tel que défini à l'une quelconque des revendications précédentes et qu'il comprend des particules de VP04 revêtues d'une couche de carbone amorphe. 14. Composite material of vanadium phosphate and carbon, characterized in that it is obtained according to a process as defined in any one of the preceding claims and that it comprises particles of VP0 4 coated with a layer of amorphous carbon.
15. Utilisation d'un matériau composite de phosphate de vanadium et de carbone obtenu selon un procédé tel que défini à l'une quelconque des revendications 1 à 13, comme précurseur pour la préparation de matériaux électrochimiquement actifs d'électrodes. 15. Use of a composite material of vanadium phosphate and carbon obtained according to a process as defined in any one of claims 1 to 13, as a precursor for the preparation of electrochemically active electrode materials.
16. Utilisation d'un matériau composite de phosphate de vanadium et de carbone obtenu selon un procédé tel que défini à l'une quelconque des revendications 1 à 13, comme matériau actif d'anode.  16. Use of a composite material of vanadium phosphate and carbon obtained according to a process as defined in any one of claims 1 to 13, as anode active material.
17. Matériau composite de formule Na3V2( 04)2F3/C, caractérisé en ce qu'il est obtenu à partir d'un matériau composite de phosphate de vanadium et de carbone de formule VP04/C tel que défini dans la revendication 14 ou obtenu selon un procédé tel que défini à l'une quelconque des revendications 1 à 13 et qu'il présente les paramètres de maille suivants : a = 9,0294(2) Â, b = 9,0445(2) Â, c = 10,7528(2) Â dans le système cristallin Amam. 17. Composite material of formula Na 3 V 2 (O 4 ) 2 F 3 / C, characterized in that it is obtained from a composite material of vanadium phosphate and carbon of formula VPO 4 / C as defined in claim 14 or obtained according to a method as defined in any one of claims 1 to 13 and having the following mesh parameters: a = 9.0294 (2) Å, b = 9.0445 (2) Â, c = 10.7528 (2) Â in the Amam crystalline system.
EP18712940.8A 2017-02-01 2018-02-01 Liquid process for preparing a vanadium phosphate-carbon composite material Pending EP3577068A1 (en)

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PCT/FR2018/050248 WO2018142082A1 (en) 2017-02-01 2018-02-01 Liquid process for preparing a vanadium phosphate-carbon composite material

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