CN115732634A - Negative electrode lithium supplement electrode sheet and preparation method and application thereof - Google Patents
Negative electrode lithium supplement electrode sheet and preparation method and application thereof Download PDFInfo
- Publication number
- CN115732634A CN115732634A CN202211612961.9A CN202211612961A CN115732634A CN 115732634 A CN115732634 A CN 115732634A CN 202211612961 A CN202211612961 A CN 202211612961A CN 115732634 A CN115732634 A CN 115732634A
- Authority
- CN
- China
- Prior art keywords
- lithium
- negative electrode
- layer
- electrode
- supplement
- 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
Links
Images
Classifications
-
- 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
Landscapes
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention provides a negative electrode lithium supplement electrode piece and a preparation method and application thereof. The negative electrode lithium supplement electrode piece comprises a negative electrode substrate and a lithium supplement layer positioned on the surface of an electrode layer of the negative electrode substrate; the lithium supplementing layer comprises a lithium metal layer and a protective layer with a porous structure, wherein the protective layer is positioned on the surface of the lithium metal layer; the protective layer comprises LiF, C and F which are distributed in a gradient manner, the LiF is directly contacted with the lithium metal layer, the LiF and the C are bonded through an F-C bond, and the C and the F are also bonded through an F-C bond. According to the negative electrode lithium supplement plate provided by the invention, the protective layer can effectively inhibit the generation of lithium dendrites in the charging and discharging process, the side reaction of the negative electrode layer and electrolyte is reduced, the increase of impedance in the use process of the battery is reduced, and meanwhile, the porous structure can improve the liquid absorption and retention capacity of the negative electrode plate, and the multiplying power and the cycle performance of the battery are improved.
Description
Technical Field
The invention belongs to the technical field of lithium ion batteries, and relates to a negative electrode lithium supplement electrode piece and a preparation method and application thereof.
Background
The lithium ion battery is widely applied to various electronic devices and electric energy storage devices due to the characteristics of high working voltage, small self-discharge, no memory effect, environmental friendliness and the like. The lithium ion battery mainly comprises a positive electrode, a negative electrode, a diaphragm and electrolyte. During the first charging (i.e., formation), a certain amount of lithium is lost from the lithium ions desorbed from the positive electrode at the negative electrode due to the formation of an SEI film or the like, thereby reducing the first efficiency of the battery and affecting the capacity and energy density of the battery.
In order to improve the first efficiency of the battery, a lithium supplement method is generally adopted in the industry. The lithium supplement method mainly comprises the steps of supplementing lithium to the positive electrode and supplementing lithium to the negative electrode. The positive electrode lithium supplement refers to adding a certain lithium-rich compound into the positive electrode, wherein all or part of Li in the compound is extracted during the first charging and reaches the negative electrode to supplement a negative electrode lithium source, and the compound loses activity after the first charging and does not participate in subsequent electrochemical reactions. The lithium supplement of the positive electrode is relatively simple, the requirement on the production environment of the battery is not high, but an inactive material can be left in the positive electrode plate, so that the conductivity of the positive electrode and the energy density of the battery are influenced. Therefore, lithium is commonly supplied to the negative electrode.
The lithium is supplemented to the negative electrode in the following ways:
(1) Directly thinning the lithium foil by rolling and attaching the lithium foil on the surface of the negative plate; in the lithium supplementing process, the lithium foil is directly contacted with air, so that the requirement on the environment is high, and if the temperature and humidity do not reach the standard, the lithium foil is easy to react with water in the air, generate heat and the like.
(2) The lithium powder is mixed with the binder and then coated on the surface of the negative electrode or mixed with the negative electrode slurry and then coated on the current collector, so that the lithium powder is light in weight, easy to agglomerate and high in risk, and brings inconvenience to industrial production; fully dispersing lithium powder, a solvent and a stabilizer, and dispersing the lithium powder on a negative plate in a certain mode, wherein most of the lithium powder has a common dispersing effect and needs to be further dried to remove the residual solvent; the method has the advantages that the passivated lithium powder is directly added in the pole piece mixing process, the requirements of the mixing process are more strict, the selection of an inert solvent is increased, and the process steps are complicated.
Therefore, how to improve the lithium supplement effect of the negative pole piece, improve the electrochemical performance of the battery, ensure the safety in the lithium supplement process, and simplify the lithium supplement process is a technical problem to be solved urgently.
Disclosure of Invention
The invention aims to provide a negative electrode lithium supplement electrode sheet and a preparation method and application thereof. According to the cathode lithium supplement pole piece provided by the invention, the surface of the lithium supplement layer is provided with the LiF, the C and the F (in atomic level) which are distributed in a gradient manner, and the porous protection layer bonded through the F-C bond effectively inhibits the generation of lithium dendrites in the lithium metal layer, the protection layer also reduces the side reaction of the cathode electrode layer and electrolyte, reduces the increase of impedance in the use process of the battery, and meanwhile, the porous structure can also improve the liquid absorption and retention capacity of the cathode piece, and improves the multiplying power and the cycle performance of the battery.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the invention provides a negative electrode lithium supplement pole piece, which comprises a negative electrode substrate and a lithium supplement layer positioned on the surface of an electrode layer of the negative electrode substrate; the lithium supplementing layer comprises a lithium metal layer and a protective layer which is positioned on the surface of the lithium metal layer and has a porous structure; the protective layer comprises LiF, C and F which are distributed in a gradient manner, the LiF is directly contacted with the lithium metal layer, the LiF and the C are bonded through an F-C bond, and the C and the F are also bonded through an F-C bond.
Preferably, the lithium supplement layer is distributed on the surface of the electrode layer continuously or at intervals.
Preferably, when the lithium supplement layers are distributed on the surface of the electrode layer at intervals, the total area of the lithium supplement layers accounts for 14% of the area of the electrode layer.
In a second aspect, the invention provides a method for preparing the negative electrode lithium-supplementing pole piece, which comprises the following steps:
(1) Spraying PTFE powder on the surface of the lithium foil, and carrying out in-situ reaction in a protective atmosphere to obtain the lithium foil with a protective layer;
(2) And (2) compounding the lithium foil with the protective layer in the step (1) on the surface of an electrode layer of a negative electrode matrix to obtain a negative electrode lithium supplement electrode sheet.
Preferably, the PTFE powder of step (1) has a D50 of 0.1 to 5 μm.
Preferably, the thickness of the PTFE powder sprayed in the step (1) is 1-8 μm.
Preferably, the thickness of the lithium foil in the step (1) is 5 to 20 μm.
Preferably, the method of spraying in step (1) comprises electrostatic spraying.
Preferably, the voltage of the electrostatic spraying is 60 to 90kV.
Preferably, the current of the electrostatic spraying is 10 to 20 muA.
Preferably, the pressure of the spraying flow rate in the electrostatic spraying process is 0.3-0.55 MPa.
Preferably, the atomization pressure in the electrostatic spraying process is 0.3-0.45 MPa.
Preferably, the fluidizing pressure of the powder supply cylinder in the electrostatic spraying process is 0.04-0.10 MPa;
preferably, in the electrostatic spraying process, the distance between the spray gun and the surface of the lithium foil is 150-300 mm.
Preferably, the temperature of the in-situ reaction in the step (1) is 250-320 ℃.
Preferably, the complexing conditions of step (2) are such that humidity < 0.3% RH.
Preferably, the compounding method of step (2) comprises roll compounding.
Preferably, the temperature of the roll lamination is 130 to 180 ℃.
Preferably, the rolling pressure of the rolling combination is 40-55T/cm 2 。
As a preferred technical scheme, the preparation method comprises the following steps:
(1) Spraying PTFE powder with the D50 of 0.1-5 mu m on the surface of a lithium foil with the thickness of 5-20 mu m in an electrostatic spraying mode at the voltage of 60-90 kV and the current of 10-20 mu A, wherein in the electrostatic spraying process, the pressure of the spraying flow rate is 0.3-0.55 MPa, the atomizing pressure is 0.3-0.45 MPa, the fluidizing pressure of a powder supply cylinder is 0.04-0.10 MPa, the distance between a spray gun and the surface of the lithium foil is 150-300 mm, the spraying thickness is 1-8 mu m, and the in-situ reaction is carried out at the temperature of 250-320 ℃ in a protective atmosphere to obtain the lithium foil with a protective layer;
(2) RH% 2 The pressure is compounded on the surface of an electrode layer of the negative electrode matrix in a rolling compounding mode to obtain a negative electrode lithium supplement electrode sheet.
In a third aspect, the present invention provides a lithium ion battery, which includes the negative electrode lithium supplement electrode sheet according to the first aspect.
In a fourth aspect, the present invention provides a battery module including the lithium ion battery according to the third aspect.
In a fifth aspect, the invention further provides a whole vehicle, where the whole vehicle includes the lithium ion battery according to the third aspect or the battery module according to the fourth aspect.
Compared with the prior art, the invention has the following beneficial effects:
(1) According to the cathode lithium supplement pole piece provided by the invention, the surface of the lithium supplement layer is provided with the LiF, the C and the F (atomic level) which are distributed in a gradient manner, and the porous protection layer is bonded through the F-C bond, so that the generation of lithium dendrite in the lithium metal layer is effectively inhibited, the side reaction of the cathode electrode layer and electrolyte is reduced by the protection layer, the increase of impedance in the use process of the battery is reduced, meanwhile, the liquid absorption and retention capacity of the cathode piece can be improved by the porous structure, and the cycle and rate performance of the battery are improved. The battery adopts the negative electrode lithium supplement pole piece provided by the invention as a negative electrode, in the preparation process of the lithium supplement layer, an electrostatic spraying mode is adopted, the particle size range and the spraying thickness of the PTFT are regulated and controlled simultaneously, the lithium supplement layer covers the surface of the negative electrode active material layer completely or is distributed on the surface of the negative electrode active material layer at intervals (the total area of the lithium supplement layer is more than or equal to 20%), the first coulombic efficiency (C3/(C1 + C2) 100% and the test condition of the data in the table 1) of the battery can reach more than 95.1%, the multiplying power performance (C5/C4 gamma 100% and the test condition of the data in the table 1) can reach more than 97.8%, and the capacity after 500 cycles at 1C (the test condition of the data in the table 1) can reach more than 97.5%.
(2) According to the preparation method of the negative electrode lithium supplement pole piece, the thickness of the protective layer is controllable and cannot be too thick in an electrostatic spraying mode, the phenomenon that lithium metal directly contacts with air to generate heat in the negative electrode lithium supplement process is avoided, a solvent is not needed, the preparation process is safe and pollution-free, the process is simple, the negative electrode lithium supplement pole piece with the excellent negative electrode lithium supplement effect can be obtained, and the preparation method is suitable for large-scale production.
Drawings
Fig. 1 shows a schematic flow chart of a preparation process of a negative electrode lithium supplement pole piece in a specific embodiment.
Detailed Description
The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitation of the present invention.
In one embodiment, the invention provides a negative electrode lithium supplement pole piece, which comprises a negative electrode substrate and a lithium supplement layer positioned on the surface of an electrode layer of the negative electrode substrate; the lithium supplementing layer comprises a lithium metal layer and a protective layer with a porous structure, wherein the protective layer is positioned on the surface of the lithium metal layer; the protective layer comprises LiF, C and F which are distributed in a gradient manner, the LiF is directly contacted with the lithium metal layer, the LiF and the C are bonded through an F-C bond, and the C and the F are also bonded through an F-C bond.
The negative electrode substrate provided by the invention is a conventional negative electrode plate without lithium supplement treatment, namely comprises a negative electrode current collector and an electrode layer (single side or double sides) positioned on the surface of the negative electrode current collector.
According to the cathode lithium supplement pole piece provided by the invention, in the protective layer structure formed by the LiF, the C and the F which are distributed in a gradient manner, the LiF, the C and the F are bonded through the F-C bonds in sequence, namely from the side in contact with the lithium metal layer, the Li atoms on the surface of the lithium metal and the F in the PTFE form LiF, the LiF and the C are connected through the F-C bonds, the middle C atoms are combined with the F through the F-C bonds and are advanced layer by layer, so that the protective layer structure of the gradient structure is obtained, the generation of lithium dendrites in the lithium metal layer is effectively inhibited, the side reaction of the cathode electrode layer and electrolyte is reduced by the protective layer, the increase of impedance in the use process of the battery is reduced, meanwhile, the liquid absorption and retention capacity of the cathode piece can be improved by the porous structure, and the cycle and rate performance of the battery are improved.
In a preferred embodiment, the lithium supplement layer is continuously or intermittently distributed on the surface of the electrode layer.
The lithium supplement layer in the invention can completely cover the surface of the electrode layer, and can also be distributed on the surface of the electrode layer at intervals.
In a preferred embodiment, when the lithium supplement layers are spaced apart on the surface of the electrode layer, the total area of the lithium supplement layers accounts for at least 14% of the area of the electrode layer, for example, 14%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or 80%.
(the upper limit thickness of the lithium foil is calculated to be 20 μm, and the proportion of the total area of the lithium supplement layer gradually increases as the thickness of the lithium foil decreases.
According to the invention, when the lithium supplement layers are distributed at intervals, the proportion of the total area of the lithium supplement layers to the area of the electrode layer is related to the thickness of the lithium supplement electrode plate, and when the thickness of the lithium supplement layer is fixed, the area of the lithium supplement layer is too low to meet the lithium supplement requirement, and the formation of a protective layer and the improvement of the energy density, multiplying power and cycle performance of the lithium ion battery are not facilitated.
In another embodiment, the present invention provides a method for preparing a negative electrode lithium supplement electrode sheet according to the above embodiment, wherein the method comprises the following steps (as shown in fig. 1):
(1) Spraying PTFE powder on the surface of the lithium foil, and carrying out in-situ reaction in a protective atmosphere to obtain the lithium foil with a protective layer;
(2) And (3) compounding the lithium foil with the protective layer in the step (1) on the surface of an electrode layer of the negative electrode substrate to obtain a negative electrode lithium supplement electrode sheet.
According to the preparation method provided by the invention, a loose and porous PTFE layer is formed on the surface of the lithium foil in a spraying manner, then the PTFE layer reacts with lithium metal on the surface of the lithium foil in situ to obtain the LiF, C and F (in atomic level) which are in gradient distribution, and the porous protection layer is bonded through an F-C bond, and the preparation process does not need to add a solvent, so that the preparation method is safe and pollution-free, and the direct contact between the lithium metal and air is avoided when the PTFE layer is compounded with a cathode matrix and in the subsequent lithium supplement process, so that the preparation method is simple in process and suitable for large-scale production.
In the invention, a spraying mode (dry powder spraying) is adopted, so that the thickness and the amount of the PTFE layer can be controlled more conveniently, a porous structure can be formed more conveniently, pores are increased on the basis of ensuring the amount, the liquid absorption and retention capacity of a negative pole piece is improved, and the multiplying power and the cycle performance of the lithium ion battery are improved. If the PTFE film is used for preparation, a protective layer which is porous and small in thickness cannot be prepared, the energy density of a battery cell cannot be obviously improved, the liquid absorption and retention capacity of a pole piece cannot be improved, and finally the multiplying power and the cycle performance of the lithium ion battery cannot be improved.
As a preferable embodiment, the PTFE powder in the step (1) has a D50 of 0.1 to 5 μm, for example, 0.1. Mu.m, 0.5. Mu.m, 1. Mu.m, 1.5. Mu.m, 2. Mu.m, 2.5. Mu.m, 3. Mu.m, 3.5. Mu.m, 4. Mu.m, 4.5. Mu.m, or 5 μm.
In the invention, the D50 of the PTFE powder in the step (1) is too small, ions are easy to agglomerate or agglomerate, the PTFE layer with uniformity and high porosity is not easy to spray, and the spraying layer is too thick and excessive due to too large PTFE powder, the shuttle time of lithium ions in a negative plate is increased, the weight of the negative plate is increased, the energy density of a lithium ion battery is reduced, and the multiplying power performance is reduced.
As a preferable embodiment, the PTFE powder spray of step (1) has a thickness of 1 to 8 μm, for example, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, or 8 μm.
In the invention, the PTFE powder sprayed in the step (1) is too thin, so that the liquid absorption and retention capacity of the negative plate cannot be improved, the inhibition effect on lithium dendrites is limited, and finally the multiplying power and the cycle performance of the lithium ion battery cannot be improved.
Meanwhile, the particle size and the spraying thickness of the PTFE powder are regulated and controlled, and the PTFE powder and the spraying thickness are cooperated to increase the liquid absorption and retention capacity of the negative pole piece, inhibit the generation of lithium dendrites, and finally realize the improvement of the energy density, the first effect and the rate performance and the cycle performance of the lithium ion battery.
In another preferred embodiment, the thickness of the lithium foil in step (1) is 5 to 20 μm, for example, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, or 20 μm.
As a preferable technical solution in another embodiment, the spraying method in step (1) includes electrostatic spraying.
In the invention, a uniform, porous and good-adhesion PTFE layer can be better formed on the surface of the lithium foil by adopting an electrostatic spraying mode.
Specifically, the voltage of the electrostatic spraying is 60 to 90kV, such as 60kV, 63kV, 65kV, 68kV, 70kV, 73kV, 75kV, 78kV, 80kV, 83kV, 85kV, 88kV or 90kV, and the like; the current for electrostatic spraying is 10 to 20 μ A, for example, 10 μ A, 11 μ A, 12 μ A, 13 μ A, 14 μ A, 15 μ A, 16 μ A, 17 μ A, 18 μ A, 19 μ A, or 20 μ A.
Further, the pressure of the spraying flow rate in the electrostatic spraying process is 0.3 to 0.55MPa, for example, 0.3MPa, 0.33MPa, 0.35MPa, 0.38MPa, 0.4MPa, 0.43MPa, 0.45MPa, 0.48MPa, 0.5MPa, 0.53MPa, or 0.55MPa; the atomization pressure in the electrostatic spraying process is 0.3-0.45 MPa, such as 0.3MPa, 0.33MPa, 0.35MPa, 0.38MPa, 0.4MPa, 0.43MPa or 0.45MPa; the fluidization pressure of the powder supply cylinder in the electrostatic spraying process is 0.04-0.10 MPa, such as 0.04MPa, 0.05MPa, 0.06MPa, 0.07MPa, 0.08MPa, 0.09MPa or 0.1 MPa.
Furthermore, in the electrostatic spraying process, the distance between the spray gun and the surface of the lithium foil is 150-300 mm, such as 150mm, 180mm, 200mm, 230mm, 250mm, 280mm or 300mm.
In the invention, the PTFE layer is regulated and controlled by regulating and controlling each parameter in the electrostatic spraying process, thereby ensuring the uniform distribution of the PTFE layer and the formation of a porous result.
As a preferred technical scheme in another embodiment, the temperature of the in-situ reaction in the step (1) is 250-320 ℃, such as 250 ℃, 260 ℃, 270 ℃, 280 ℃, 290 ℃, 300 ℃, 310 ℃ or 320 ℃, etc.
As a preferred embodiment of the present invention, in the compounding conditions in step (2), the humidity is less than 0.3% RH, for example, 0.28% RH, 0.25% RH, 0.23% RH, 0.2% RH, 0.15% RH or 0.1% RH.
As a preferable technical solution in another embodiment, the compounding method in the step (2) includes roll compounding.
Further, the temperature of the roll lamination is 130 to 180 ℃, such as 130 ℃, 140 ℃, 150 ℃, 160 ℃, 170 ℃ or 180 ℃ and the like.
Furthermore, the rolling pressure of the rolling combination is 40-55T/cm 2 E.g. 40T/cm 2 、43T/cm 2 、45T/cm 2 、48T/cm 2 、50T/cm 2 、53T/cm 2 Or 55T/cm 2 And the like.
As a preferable technical solution in another specific embodiment, the preparation method comprises the steps of:
(1) Spraying PTFE powder with the D50 of 0.1-5 mu m on the surface of a lithium foil with the thickness of 5-20 mu m by adopting an electrostatic spraying mode at the voltage of 60-90 kV and the current of 10-20 mu A, wherein in the electrostatic spraying process, the pressure of the spraying flow rate is 0.3-0.55 MPa, the atomizing pressure is 0.3-0.45 MPa, the fluidizing pressure of a powder supply cylinder is 0.04-0.10 MPa, the distance between a spray gun and the surface of the lithium foil is 150-300 mm, the spraying thickness is 1-8 mu m, and the in-situ reaction is carried out at the temperature of 250-320 ℃ in a protective atmosphere to obtain the lithium foil with a protective layer;
(2) Humidity < 0.3% RH%The lithium foil with the protective layer is heated at 130-180 ℃ and 40-55T/cm 2 The pressure is compounded on the surface of an electrode layer of the negative electrode matrix in a rolling compounding mode to obtain a negative electrode lithium supplement electrode sheet.
An embodiment of the present invention provides a lithium ion battery, which includes the negative electrode lithium supplement electrode sheet described in the first aspect.
The lithium ion battery provided by the invention comprises a liquid lithium ion battery and a solid lithium ion battery.
The liquid lithium ion battery comprises a positive electrode, a negative electrode, a diaphragm and electrolyte, wherein the negative electrode comprises the negative electrode plate in the above specific embodiment.
The solid lithium ion battery comprises a positive electrode, a negative electrode and a solid electrolyte layer, wherein the negative electrode comprises the composite negative electrode material in the above embodiment.
The types of the inactive materials in the positive electrode, the diaphragm, the electrolyte and the negative electrode of the liquid lithium ion battery or the solid lithium ion battery are all selected by the conventional technology.
The positive electrode generally comprises a positive electrode current collector and an active layer located on the surface of the positive electrode current collector, the active layer generally comprises a positive electrode active material, a conductive agent and a binder, the negative electrode generally comprises a negative electrode current collector and an active layer on the surface of the negative electrode current collector, and the active layer generally comprises a negative electrode active material (including the composite negative electrode material in the above-mentioned embodiment), a conductive agent and a binder.
The positive electrode current collector is not particularly limited as long as it has fine irregularities formed on the surface thereof to improve adhesion of the positive electrode active material. For example, positive electrode current collectors in various shapes such as films, sheets, foils, nets, porous bodies, foams and non-woven fabrics may be used.
The negative electrode current collector is not particularly restricted so long as it has conductivity without causing chemical changes in the battery. Specifically, copper, stainless steel, aluminum, nickel, titanium, or a metal current collector surface-treated with carbon or other substances may be used.
The positive electrode active material is a compound capable of reversibly intercalating and deintercalating lithium, and specifically, may include a lithium transition metal composite oxide containing lithium and at least one transition metal selected from the group consisting of nickel, cobalt, manganese, and aluminum; preferably, it may be lithium and a transition metal such as nickel, cobalt or manganese.
The negative electrode active material can also comprise other negative electrode materials, such as one or more of silicon-based materials, tin-based materials and lithium titanate. Wherein, the silicon-based material can be one or more of simple substance silicon, silicon-oxygen compound, silicon-carbon compound and silicon alloy; the tin-based material can be one or more of simple substance tin, tin oxide compound and tin alloy.
The binder may include at least one selected from the group consisting of polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer, styrene-butadiene rubber, and fluororubber.
The conductive agent may comprise graphite, such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers and metal fibers; conductive tubes such as carbon nanotubes; metal powders such as fluorocarbon powders, aluminum powders, and nickel powders; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and polyphenylene derivatives.
The separator mainly functions to separate the anode and the cathode and to provide a moving path for lithium ions. Any separator may be used without particular limitation so long as it is a separator commonly used in secondary batteries. In particular, a separator having excellent wettability with an electrolytic solution and low resistance to ion movement in an electrolyte is preferable. Specifically, a porous polymer film, for example, a porous polymer film manufactured using a polyolefin-based polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene/butene copolymer, an ethylene/hexene copolymer, and an ethylene/methacrylate copolymer, or having a laminated structure of two or more layers thereof, may be used. Also, typical porous nonwoven fabrics, for example, nonwoven fabrics formed of glass fibers having a high melting point, polyethylene terephthalate fibers, and the like, may be used. In addition, a coating separator including a ceramic component or a polymer material may be used to ensure heat resistance or mechanical strength, and may be selectively used in a single layer or a multi-layer structure.
The electrolyte may include an organic solvent and a lithium salt.
Any organic solvent may be used without particular limitation so long as it can serve as a medium through which ions participating in the electrochemical reaction of the battery can move; any compound may be used as the lithium salt without particular limitation so long as it can provide lithium ions used in a lithium secondary battery, i.e., an electrolyte used in a conventional liquid battery, and the present invention is applicable.
The solid electrolyte layer includes a solid electrolyte, and the solid electrolyte particles may include one or more of a polymeric component, an oxide solid electrolyte, a sulfide solid electrolyte, a halide solid electrolyte, a borate solid electrolyte, a nitride solid electrolyte, or a hydride solid electrolyte.
In another embodiment of the present invention, a battery module is provided, which includes the lithium ion battery according to an embodiment.
Further, the invention also provides a whole vehicle, which comprises the lithium ion battery in one embodiment or the battery module in another embodiment.
Example 1
The present embodiment provides a lithium pole piece is mended to negative pole, provides based on above-mentioned embodiment:
the negative electrode lithium supplement electrode piece comprises a negative electrode substrate and a lithium supplement layer positioned on the surface of an electrode layer of the negative electrode substrate; the lithium supplementing layer comprises a lithium metal layer and a protective layer which is positioned on the surface of the lithium metal layer and has a porous structure; the protective layer comprises LiF, C and F which are distributed in a gradient manner, the LiF is directly contacted with the lithium metal layer, the LiF and the C are bonded through an F-C bond, and the C and the F are also bonded through an F-C bond;
the negative electrode substrate comprises a negative electrode current collector copper foil and a graphite electrode layer positioned on the surface of the copper foil (the mass ratio of the artificial graphite to the conductive carbon black to the polyvinylidene fluoride is 90.
The preparation method of the negative electrode lithium supplement pole piece is provided based on another specific embodiment:
the D50 of the PTFE powder was 3 μm and the thickness of the lithium foil was 10 μm (before spraying), and the spraying was carried out by electrostatic spraying:
wherein in the step (1), the voltage of electrostatic spraying is 70kV, the current is 15 muA, the flow velocity pressure is 0.4MPa, the atomization pressure is 0.4MPa, the distance from a spray gun to a workpiece (namely a lithium foil to be sprayed) is 200mm, the final spraying thickness is 5μm, and the temperature of in-situ reaction is 300 ℃;
in the step (2), the composite is combined with the negative electrode substrate by roll-press combination, and is continuously combined (the lithium supplement layer covers the electrode layer) in an environment with a humidity of 0.2% RH at 50T/cm 2 And (3) rolling and compounding at 150 ℃ to obtain the negative electrode lithium supplement electrode sheet.
Example 2
This embodiment provides a lithium pole piece is mended to negative pole, provides based on above-mentioned embodiment:
the negative electrode lithium supplement electrode piece comprises a negative electrode substrate and a lithium supplement layer positioned on the surface of an electrode layer of the negative electrode substrate; the lithium supplementing layer comprises a lithium metal layer and a protective layer with a porous structure, wherein the protective layer is positioned on the surface of the lithium metal layer; the protective layer comprises LiF, C and F which are distributed in a gradient manner, the LiF is directly contacted with the lithium metal layer, the LiF and the C are bonded through an F-C bond, and the C and the F are also bonded through an F-C bond;
the negative electrode matrix comprises a negative electrode current collector copper foil and a graphite electrode layer positioned on the surface of the copper foil (the mass ratio of the artificial graphite to the conductive carbon black to the polyvinylidene fluoride is 90.
The preparation method of the negative electrode lithium supplement pole piece is provided based on another specific embodiment:
the D50 of the PTFE powder was 0.5 μm, the thickness of the lithium foil was 6 μm (before spraying), and the spraying was carried out by electrostatic spraying:
wherein in the step (1), the voltage of electrostatic spraying is 90kV, the current is 20 muA, the flow velocity pressure is 0.3MPa, the atomization pressure is 0.35MPa, the distance from a spray gun to a workpiece (namely a lithium foil to be sprayed) is 200mm, the final spraying thickness is 3μm, and the temperature of in-situ reaction is 320 ℃;
in the step (2), the composite is combined with the negative electrode substrate by roll-press combination, and is continuously combined (the lithium supplement layer covers the electrode layer) in an environment with a humidity of 0.25% RH at 45T/cm 2 And (3) rolling and compounding at 180 ℃ to obtain the negative electrode lithium supplement electrode sheet.
Example 3
This embodiment provides a lithium pole piece is mended to negative pole, provides based on above-mentioned embodiment:
the negative electrode lithium supplement electrode piece comprises a negative electrode substrate and a lithium supplement layer positioned on the surface of an electrode layer of the negative electrode substrate; the lithium supplementing layer comprises a lithium metal layer and a protective layer which is positioned on the surface of the lithium metal layer and has a porous structure; the protective layer comprises LiF, C and F which are distributed in a gradient manner, the LiF is directly contacted with the lithium metal layer, the LiF and the C are bonded through an F-C bond, and the C and the F are also bonded through an F-C bond;
the negative electrode matrix comprises a negative electrode current collector copper foil and a silicon carbide electrode layer positioned on the surface of the copper foil (the mass ratio of silicon carbide, conductive carbon black and polyvinylidene fluoride is 90.
The preparation method of the negative electrode lithium supplement pole piece is provided based on another specific embodiment:
the D50 of the PTFE powder was 3.5 μm, the thickness of the lithium foil was 8 μm (not before spraying), and the spraying was carried out by electrostatic spraying:
wherein in the step (1), the voltage of electrostatic spraying is 60kV, the current is 10 muA, the flow velocity pressure is 0.3MPa, the atomization pressure is 0.35MPa, the distance from a spray gun to a workpiece (namely a lithium foil to be sprayed) is 200mm, the final spraying thickness is 8μm, and the temperature of in-situ reaction is 320 ℃;
in the step (2), the composite is carried out by roll-to-roll compounding with the negative electrode substrate, and in order to continuously compound (the lithium supplement layer covers the electrode layer), in an environment with a humidity of 0.25% RH, at 45T/cm 2 And (3) rolling and compounding at 180 ℃ to obtain the negative electrode lithium supplement electrode sheet.
Example 4
The difference between this embodiment and embodiment 1 is that the lithium supplement layers in step (1) of this embodiment are distributed at intervals, and the total area of the lithium supplement layers is 50% of the area of the electrode layer.
The remaining preparation methods and parameters were in accordance with example 1.
Example 5
The difference between this embodiment and embodiment 1 is that the lithium supplement layers in step (1) of this embodiment are distributed at intervals, and the distribution area is 10% of the electrode layer area.
The remaining preparation methods and parameters were in accordance with example 1.
Example 6
This example is different from example 1 in that the PTFE powder in step (1) of this example had a D50 of 6 μm and a spray thickness of 8 μm.
The remaining preparation methods and parameters were in accordance with example 1.
Example 7
The difference between this example and example 1 is that the D50 of the PTFE powder in step (1) of this example was 3.5 μm, and the spray thickness was 10 μm.
The remaining preparation methods and parameters were in accordance with example 1.
Example 8
The difference between this example and example 1 is that the spraying manner in step (1) of this example is air spraying, the spraying pressure is 0.3MPa, and the distance from the spray gun to the workpiece (i.e. the lithium foil to be sprayed) is 200mm.
The remaining preparation methods and parameters were in accordance with example 1.
Comparative example 1
The comparative example is different from example 1 in that the step (1) is not performed, and the lithium foil is directly roll-combined with the negative electrode substrate.
The remaining preparation methods and parameters were in accordance with example 1.
Comparative example 2
The comparative example is different from example 1 in that in the step (1) of the comparative example, a PTFE film having a thickness of 5 μm is laminated on the surface of the lithium sheet, and then an in-situ reaction is performed.
The remaining preparation methods and parameters were in accordance with example 1.
The negative electrode lithium supplement pole pieces provided in the embodiments 1 to 8 and the comparative examples 1 to 2 are used as a negative electrode, lithium iron phosphate is used as a positive electrode, enjind 12T30 is used as a diaphragm, 10 lithium supplement negative pole pieces and 9 positive pole pieces form a core package by an automatic lamination machine, and the lithium ion secondary battery is obtained through liquid injection and packaging. .
The electrochemical performance of the cells provided in examples 1-8 and comparative examples 1-2 was tested by the following specific test methods:
the first coulombic efficiency test is carried out under the following test conditions: charging at 25 deg.C under constant current of 0.1C rate to 3.65V to obtain charge capacity C 1 The constant voltage charging is carried out under the voltage of 3.65V until the voltage is 0.05C, and the cut-off is carried out, thus obtaining the charging capacity C 2 (ii) a Standing for 10min; discharging at 0.1C rate to 2.5V to obtain discharge capacity C 3 . First coulombic efficiency (%) = C 3 /(C 1 +C 2 )╳100％。
And (3) rate discharge performance test: charging to 3.65V at constant current with 0.1C multiplying power at 25 deg.C, and stopping charging at constant voltage of 3.65V to 0.05C; standing for 10min; discharging to 2.5V at 0.1C rate; standing for 10min; obtaining the discharge capacity C 4 . Then charging to 3.65V by constant current with 1C multiplying power, and charging to 0.05C by constant voltage under the voltage of 3.65V; standing for 10min; discharging to 2.5V at 1C rate to obtain discharge capacity C 5 (ii) a Rate capability = C 5 /C 4 ╳100％。
And (3) cycle testing: charging to 3.65V at constant current of 1C multiplying power at 25 ℃, and charging to 0.05C at constant voltage of 3.65V to cut off; standing for 10min; discharging to 2.5V at 1C rate, and standing for 10min. The above process was repeated 500 times.
The test results are shown in table 1.
TABLE 1
From the data results of the embodiments 4 and 5, it can be seen that the lithium supplement layers distributed at intervals have too small areas, cannot meet the first and continuous lithium supplement requirements, cannot significantly improve the liquid absorption and retention capacities of the negative electrode plate, and are not beneficial to the first improvement of coulomb efficiency, rate capability and cycle performance.
From the data results of example 1, example 6 and example 7, it is clear that the particle size of PTFE is too large to form a thin protective layer, increasing the internal resistance of the lithium ion secondary battery, which is not favorable for improving the rate capability and cycle performance; the too large thickness of the spraying can affect the shuttle speed of the lithium ions, increase the internal resistance of the lithium ion secondary battery and be not beneficial to the improvement of the multiplying power performance and the cycle performance.
As can be seen from the data results of examples 1 and 8, the non-electrostatic spraying of PTFE powder does not provide a uniform, smooth, thin, and porous protective layer, which is detrimental to the improvement of battery rate performance and cycle performance.
As can be seen from the data results of example 1 and comparative example 1, in the negative electrode lithium supplement pole piece, the lithium supplement layer does not contain a protective layer, the lithium foil is oxidized in the air to generate heat to cause excessive consumption, and the protective layer is not on the surface to cause lithium dendrite growth or increase the risk of lithium dendrite growth, which is not favorable for the improvement of the first coulomb efficiency, rate capability and cycle performance.
From the data results of example 1 and comparative example 2, it can be seen that the protective layer prepared using PTFE film is non-porous and has inferior rate capability and cycle performance compared to powder spray coating (invention). .
In summary, the cathode lithium supplement electrode sheet provided by the invention has the advantages that the surface of the lithium supplement layer is provided with the LiF, the C and the F (atomic level) which are distributed in a gradient manner, and the porous protective layer bonded by the F-C bond effectively inhibits the production of lithium dendrites in the lithium metal layer, the side reaction of the cathode and the electrolyte is reduced by the protective layer, and the increase of impedance in the using process of the battery is reducedAnd meanwhile, the porous structure can also improve the liquid absorption and retention capacity of the negative plate, and the multiplying power and the cycle performance of the battery are improved. The battery adopts the negative electrode lithium supplement electrode sheet provided by the invention as a negative electrode, in the preparation process of the lithium supplement layer, the electrostatic spraying mode is adopted, the particle size range and the spraying thickness of the PTFT are regulated and controlled simultaneously, the lithium supplement layer completely covers the surface of the negative electrode active material layer or is distributed on the surface of the negative electrode active material layer at intervals (the total area of the lithium supplement layer is more than or equal to 20 percent), and the first coulombic efficiency (C) of the battery is realized 3 /(C 1 +C 2 Gamma 100%, test conditions for data in table 1) can reach over 95.1%, and rate performance (C) 5 /C 4 Gamma 100%, test conditions of data in table 1) can reach more than 97.8%, and capacity retention rate after 500 cycles at 1C (test conditions of data in table 1) can reach more than 97.5%.
The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure of the present invention.
Claims (10)
1. The negative electrode lithium supplementing pole piece is characterized by comprising a negative electrode substrate and a lithium supplementing layer positioned on the surface of an electrode layer of the negative electrode substrate; the lithium supplementing layer comprises a lithium metal layer and a protective layer with a porous structure, wherein the protective layer is positioned on the surface of the lithium metal layer; the protective layer comprises LiF, C and F which are distributed in a gradient manner, the LiF is directly contacted with the lithium metal layer, the LiF and the C are bonded through an F-C bond, and the C and the F are also bonded through an F-C bond.
2. The negative electrode lithium supplementing pole piece according to claim 1, wherein the lithium supplementing layer is distributed on the surface of the electrode layer continuously or at intervals;
preferably, when the lithium supplement layers are distributed on the surface of the electrode layer at intervals, the total area of the lithium supplement layers accounts for at least 14% of the area of the electrode layer.
3. The preparation method of the negative electrode lithium-supplementing pole piece according to claim 1 or 2, characterized by comprising the following steps:
(1) Spraying PTFE powder on the surface of a lithium foil, and carrying out in-situ reaction in a protective atmosphere to obtain the lithium foil with a protective layer;
(2) And (3) compounding the lithium foil with the protective layer in the step (1) on the surface of an electrode layer of the negative electrode substrate to obtain a negative electrode lithium supplement electrode sheet.
4. The preparation method of the negative electrode lithium-supplementing pole piece according to claim 3, wherein the D50 of the PTFE powder in the step (1) is 0.1-5 μm;
preferably, the thickness of the PTFE powder sprayed in the step (1) is 1-8 μm;
preferably, the thickness of the lithium foil in the step (1) is 5 to 20 μm.
5. The preparation method of the negative electrode lithium-supplementing pole piece according to claim 3 or 4, characterized in that the spraying method in the step (1) comprises electrostatic spraying;
preferably, the voltage of the electrostatic spraying is 60-90 kV;
preferably, the current of the electrostatic spraying is 10-20 muA;
preferably, the pressure of the spraying flow rate in the electrostatic spraying process is 0.3-0.55 MPa;
preferably, the atomization pressure in the electrostatic spraying process is 0.3-0.45 MPa;
preferably, the fluidizing pressure of the powder supply cylinder in the electrostatic spraying process is 0.04-0.10 MPa;
preferably, in the electrostatic spraying process, the distance between the spray gun and the surface of the lithium foil is 150-300 mm.
6. The preparation method of the negative electrode lithium-supplementing pole piece according to any one of claims 3 to 5, wherein the temperature of the in-situ reaction in the step (1) is 250 to 320 ℃;
preferably, the complexing conditions of step (2) are such that humidity < 0.3% RH;
preferably, the compounding method of step (2) comprises roll compounding;
preferably, the temperature of the rolling and compounding is 130-180 ℃;
preferably, the rolling pressure of the rolling combination is 40-55T/cm 2 。
7. The preparation method of the negative electrode lithium supplement pole piece according to any one of claims 3 to 6, wherein the preparation method comprises the following steps:
(1) Spraying PTFE powder with the D50 of 0.1-5 mu m on the surface of a lithium foil with the thickness of 5-20 mu m in an electrostatic spraying mode at the voltage of 60-90 kV and the current of 10-20 mu A, wherein in the electrostatic spraying process, the pressure of the spraying flow rate is 0.3-0.55 MPa, the atomizing pressure is 0.3-0.45 MPa, the fluidizing pressure of a powder supply cylinder is 0.04-0.10 MPa, the distance between a spray gun and the surface of the lithium foil is 150-300 mm, the spraying thickness is 1-8 mu m, and the in-situ reaction is carried out at the temperature of 250-320 ℃ in a protective atmosphere to obtain the lithium foil with a protective layer;
(2) Humidity < 0.3% RH, heating the lithium foil with the protective layer of step (1) at a temperature of 130-180 deg.C and a temperature of 40-55T/cm 2 The pressure is compounded on the surface of an electrode layer of the negative electrode matrix in a rolling compounding mode to obtain a negative electrode lithium supplement electrode sheet.
8. A lithium ion battery, characterized in that the lithium ion battery comprises the negative electrode lithium supplement electrode sheet according to claim 1 or 2.
9. A battery module characterized by comprising the lithium ion battery according to claim 8.
10. An entire vehicle, characterized in that the entire vehicle comprises the lithium ion battery of claim 8 or the battery module of claim 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211612961.9A CN115732634A (en) | 2022-12-15 | 2022-12-15 | Negative electrode lithium supplement electrode sheet and preparation method and application thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211612961.9A CN115732634A (en) | 2022-12-15 | 2022-12-15 | Negative electrode lithium supplement electrode sheet and preparation method and application thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115732634A true CN115732634A (en) | 2023-03-03 |
Family
ID=85301406
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202211612961.9A Pending CN115732634A (en) | 2022-12-15 | 2022-12-15 | Negative electrode lithium supplement electrode sheet and preparation method and application thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115732634A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117558873A (en) * | 2024-01-09 | 2024-02-13 | 上海瑞浦青创新能源有限公司 | Lithium supplementing negative electrode sheet, preparation method thereof and lithium ion battery |
-
2022
- 2022-12-15 CN CN202211612961.9A patent/CN115732634A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117558873A (en) * | 2024-01-09 | 2024-02-13 | 上海瑞浦青创新能源有限公司 | Lithium supplementing negative electrode sheet, preparation method thereof and lithium ion battery |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN103053063B (en) | It is coated with the positive electrode collector of priming paint and comprises the Mg secondary cell of described positive electrode collector | |
| US9608260B2 (en) | Anode active material having high density and preparation method thereof | |
| CN110676420A (en) | Lithium ion battery's lithium diaphragm of mending | |
| CN107768720B (en) | Non-negative secondary lithium battery based on liquid electrolyte | |
| CN110556490B (en) | Diaphragm with lithium layer on surface, preparation method thereof and lithium ion battery | |
| EP3335260B1 (en) | Method of preparing electrode for lithium secondary battery and electrode for lithium secondary battery prepared thereby | |
| CN202259533U (en) | Pole piece of lithium ion battery and lithium ion battery | |
| CN111490252A (en) | Lithium metal protective layer, preparation method thereof and battery with same | |
| CN112467076B (en) | Lithium ion battery | |
| CN104966814B (en) | A kind of lithium anode of high security and preparation method thereof | |
| KR20060101312A (en) | Negative electrode for lithium ion secondary battery, producing method therefor, and lithium ion secondary battery using the negative electrode | |
| CN113394383B (en) | Coating method of positive electrode material for sulfide solid-state battery | |
| CN102303007A (en) | Method for coating electrode plate for lithium ion battery, electrode plate for lithium ion battery, and lithium ion battery | |
| CN112736277A (en) | Solid electrolyte-lithium negative electrode complex, method for producing same, and all-solid-state lithium secondary battery | |
| CN112820847A (en) | Silicon-based negative electrode material and preparation method thereof, lithium ion battery and electric appliance | |
| CN103035925A (en) | Lithium-ion power battery, lithium-ion power battery current collecting body, negative electrode pole piece | |
| CN115732634A (en) | Negative electrode lithium supplement electrode sheet and preparation method and application thereof | |
| Hou et al. | Recent development of low temperature plasma technology for lithium-ion battery materials | |
| CN114141981A (en) | Positive pole piece and preparation method and application thereof | |
| CN113497217B (en) | Electrode, preparation method thereof and battery | |
| CN110600684A (en) | Silicon-carbon negative electrode material for lithium ion battery and preparation method thereof | |
| CN101393980A (en) | Silicon cathode, lithium ion secondary battery comprising the same and manufacturing method therefor | |
| CN108899470B (en) | Preparation method of Li-S battery positive plate sandwich structure | |
| CN114497440B (en) | Negative plate and battery comprising same | |
| JP7465362B2 (en) | Anode piece and its preparation method, battery and electronic device using said anode piece |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |