CN112661146B - Preparation method of laminated fluorinated graphene for positive electrode of lithium battery - Google Patents
Preparation method of laminated fluorinated graphene for positive electrode of lithium battery Download PDFInfo
- Publication number
- CN112661146B CN112661146B CN202011555033.4A CN202011555033A CN112661146B CN 112661146 B CN112661146 B CN 112661146B CN 202011555033 A CN202011555033 A CN 202011555033A CN 112661146 B CN112661146 B CN 112661146B
- Authority
- CN
- China
- Prior art keywords
- graphene
- laminated
- fluorinated graphene
- ratio
- alloy
- 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.)
- Active
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
Abstract
The embodiment of the invention provides a preparation method of laminated fluorinated graphene of a lithium battery positive electrode, which comprises the following steps: shearing, emulsifying, homogenizing, freeze-drying and annealing the mixed solution of the N-layer graphene and the stabilizing agent to obtain laminated graphene; wherein N is more than or equal to 3 and less than or equal to 10, and is a positive integer; the stabilizing agent is polyvinyl alcohol, and the mass ratio of the graphene to the polyvinyl alcohol is 1-2: 1; carrying out high-temperature fluorination on the laminated graphene under the assistance of alloy balls to obtain laminated fluorinated graphene; the ratio of C-C bonds on the surface of the laminated fluorinated graphene is 10-20%; therefore, the fluorinated graphene has a laminated sheet stacking structure, so that more reaction sites can be provided, 10-20% of C-C bonds are reserved on the surface of the fluorinated graphene, and the conductivity of the material is improved.
Description
Technical Field
The invention relates to the field of lithium primary batteries, in particular to a preparation method of laminated fluorinated graphene of a positive electrode of a lithium battery.
Background
Carbon fluoride material (CF)x) The lithium primary battery (lithium/carbon fluoride battery) solid-state anode material is the lithium primary battery with the highest theoretical energy density in the world at present, and has wide application prospect in the fields of electronic devices, biomedicine, equipment power supplies and the like. The carbon fluoride material has different properties depending on the carbon source, and common carbon fluoride materials include carbon fluoride fiber and graphite fluoride.
With the rapid development of nanomaterials, carbon fluoride nanotubes and graphene which take nanocarbon materials such as carbon nanotubes and graphene as carbon sources are also developed and utilized successively, lithium/carbon fluoride batteries which take the carbon fluoride nanotubes and the graphene as positive electrode materials are lithium primary batteries with the highest specific energy, but the fluorination reaction rate is high, and with the improvement of the fluorine-carbon ratio, a large amount of fluorine atoms exist on the surface of the materials in the form of carbon-fluorine bonds, so that the conductivity of the materials is seriously influenced, and the rate capability of the batteries is further influenced.
Disclosure of Invention
In view of this, the invention provides a preparation method of laminated fluorinated graphene for a positive electrode of a lithium battery, so as to obtain fluorinated graphene with high fluorocarbon ratio and high conductivity.
In order to achieve the purpose, the technical scheme of the invention is realized as follows:
the embodiment of the invention provides a preparation method of laminated fluorinated graphene of a lithium battery positive electrode, which comprises the following steps:
shearing, emulsifying, homogenizing, freeze-drying and annealing the mixed solution of the multilayer graphene and the stabilizing agent to obtain laminated graphene;
and carrying out high-temperature fluorination with the aid of alloy balls to obtain the laminated fluorinated graphene.
Wherein the method further comprises:
(1) mixing and grinding N-layer graphene and polyvinyl alcohol according to the mass ratio of 1-2: 1 for 10 minutes, mixing the mixture in deionized water according to the proportion of 10-20%, shearing and emulsifying the mixed solution at a high speed of 2000-4000 rpm for 30-90 minutes, and then keeping the homogeneous solution at the pressure of 1000-1500 pascals for 30-60 minutes by using a high-pressure homogenizer to obtain the homogeneous solution;
(2) placing the solution in the step (1) in a freeze dryer, freezing for 2 hours at-75 ℃ in a freezing chamber, placing in a drying chamber, vacuumizing to 1 Pa, drying until the moisture is completely removed, then placing the dried mixed powder in a tubular furnace, heating to 500 ℃ at the heating rate of 5 ℃ per minute, preserving the heat for 3 hours, cooling along with the furnace to obtain laminated graphene, wherein the protective gas of the tubular furnace is argon, and the flow of the argon is kept at 100 standard milliliters per minute;
(3) adding the graphene obtained in the step (2) and alloy balls with different sizes and proportions into a fluorination furnace with a stirring paddle, sealing, vacuumizing, removing oxygen and water in a bin by using inert gas at 100 ℃, and repeating for 3 times;
(4) starting a stirring paddle, turning over the alloy balls and the graphene at the rotating speed of 100-300 revolutions per minute, switching to introduce 20% fluorine/nitrogen mixed gas, controlling the pressure at 80-90 kPa, and operating for 30 minutes;
(5) controlling the temperature in the furnace, firstly heating to 180 ℃ at a heating rate of 2 ℃ per minute, preserving heat for 1-3 hours, then heating to 400-500 ℃ at a heating rate of 4 ℃ per minute, preserving heat for 3-6 hours, controlling a cooling rate to 4-6 ℃ per minute until the temperature reaches room temperature, then vacuumizing, treating extracted residual fluorine gas and byproducts in the furnace with alkali liquor, and sieving with a 10-mesh screen to obtain the fluorinated graphene.
The alloy balls are obtained by processing Monel alloy, the diameters of the alloy balls are 5 mm, 10 mm and 15 mm, the number ratio of the alloy balls with different diameters is 4:2:1, and the mass ratio of the alloy balls to graphene is 10-20: 1.
Wherein the fluorine-carbon ratio of the fluorinated graphene is 0.8-1.1, and the conductivity is 3 multiplied by 10-8To 9X 10-8The Siemens/m range, the size distribution is 2-25 microns.
According to the preparation method of the laminated graphene fluoride for the positive electrode of the lithium battery, provided by the embodiment of the invention, the laminated graphene is obtained by shearing, emulsifying, homogenizing, freeze-drying and annealing a mixed solution of N layers of graphene and a stabilizing agent; n is more than or equal to 3 and less than or equal to 10, and is a positive integer; then, carrying out alloy ball-assisted high-temperature fluorination on the laminated graphene to obtain the laminated fluorinated graphene, wherein the C-C bond ratio on the surface of the laminated fluorinated graphene is 10-20%; therefore, the fluorinated graphene has a laminated lamellar stacking structure, so that more reaction sites can be provided, 10-20% of C-C bonds are reserved on the surface of the fluorinated graphene, the conductivity of the material is improved, and the laminated fluorinated graphene with high fluorocarbon ratio and high conductivity is applied to a lithium battery positive electrode material to obtain a high-power lithium/fluorinated graphene battery.
Drawings
Fig. 1 is an SEM image of a positive electrode laminated fluorinated graphene of a lithium battery according to an embodiment of the present invention;
fig. 2 is an XPS diagram of a positive electrode laminated fluorinated graphene of a lithium battery according to an embodiment of the present invention;
fig. 3 is a discharge rate test chart of a lithium/fluorinated graphene battery according to an embodiment of the present invention
FIG. 4 is an SEM image of a multilayer fluorinated graphene provided in a comparative example of the present invention
FIG. 5 is a discharge rate test chart of a lithium/fluorinated graphene battery provided in a comparative manner according to the present invention
FIG. 6 is an SEM image of a few-layer fluorinated graphene provided in a comparative example of the present invention
FIG. 7 is a discharge rate test chart of a lithium/fluorinated graphene battery provided in a comparative manner according to the present invention
Detailed Description
The present invention will be described in further detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
Before further detailed description of the present invention, terms and expressions referred to in the embodiments of the present invention are described, and the terms and expressions referred to in the embodiments of the present invention are applicable to the following explanations.
1) Direct fluorination: the material is directly treated with a fluorine-containing gas.
2) Monel alloy: also called nickel alloy, is an alloy formed by adding other elements such as copper, iron, manganese and the like to a metal nickel base, and has excellent corrosion resistance.
3) Fluorine-carbon ratio: the proportion of fluorine atoms to carbon atoms in the graphite fluoride reflects the degree of fluorination.
4) C ═ C bond: i.e., carbon-carbon bonds, in graphite fluoride materials, carbon-carbon bonds directly affect the electrical conductivity of the material.
5) Discharge rate: generally indicated by C, represents the current level of the cell at one hour of complete discharge, with higher rates representing greater cell discharge current, e.g., a cell rated at 2200 ma at 1C for 1 hour of complete discharge, which is 2200 ma.
6) Specific capacity: milliampere hours per gram, abbreviated as mAh/g.
Referring to fig. 1 to 7, in order to provide a preparation method of laminated graphene fluoride for a positive electrode of a lithium battery according to an embodiment of the present invention, a mixed solution of N-layer graphene and a stabilizer is subjected to shearing emulsification, homogenization, freeze drying, and annealing to obtain laminated graphene; n is more than or equal to 3 and less than or equal to 10, and is a positive integer; then, carrying out alloy ball-assisted high-temperature fluorination on the laminated graphene to obtain the laminated fluorinated graphene, wherein the C-C bond ratio on the surface of the laminated fluorinated graphene is 10-20%; therefore, the fluorinated graphene has a laminated lamellar stacking structure, so that more reaction sites can be provided, 10-20% of C-C bonds are reserved on the surface of the fluorinated graphene, the conductivity of the material is improved, and the laminated fluorinated graphene with high fluorocarbon ratio and high conductivity is applied to a lithium battery positive electrode material to obtain a high-power lithium/fluorinated graphene battery.
The polyvinyl alcohol serving as the stabilizer can enable the multilayer graphene to be stacked into a stacked structure through shearing, emulsifying, homogenizing and freeze-drying treatment, then forms pyrolytic carbon between the stacked structures of the multilayer graphene through annealing treatment, plays a role in stabilizing the appearance, buffers the damage of high-temperature fluorination to the material structure in the subsequent fluorination process, and stabilizes the special structure of the stacked fluorinated graphene;
in an embodiment, the method further comprises:
(1) mixing and grinding N-layer graphene and polyvinyl alcohol according to a mass ratio of 1-2: 1 for 10 minutes, mixing the mixture in deionized water according to a proportion of 10-20%, shearing and emulsifying the mixed solution at a high speed of 2000-4000 rpm for 30-90 minutes, and then keeping the homogeneous solution at a pressure of 1000-1500 pascals for 30-60 minutes through a high-pressure homogenizer to obtain a homogeneous solution;
(2) placing the solution in the step (1) in a freeze dryer, freezing for 2 hours at-75 ℃ in a freezing chamber, placing in a drying chamber, vacuumizing to 1 Pa, drying until the moisture is completely removed, then placing the dried mixed powder in a tubular furnace, heating to 500 ℃ at the heating rate of 5 ℃ per minute, preserving the heat for 3 hours, cooling along with the furnace to obtain laminated graphene, wherein the protective gas of the tubular furnace is argon, and the flow of the argon is kept at 100 standard milliliters per minute;
(3) adding the graphene obtained in the step (2) and alloy balls with different sizes and proportions into a fluorination furnace with a stirring paddle, sealing, vacuumizing, removing oxygen and water in a bin by using inert gas at 100 ℃, and repeating for 3 times;
(4) starting a stirring paddle, turning over the alloy balls and the graphene at the rotating speed of 100-300 revolutions per minute, switching to introduce 20% fluorine/nitrogen mixed gas, controlling the pressure at 80-90 kPa, and operating for 30 minutes;
(5) controlling the temperature in the furnace, firstly heating to 180 ℃ at a heating rate of 2 ℃ per minute, preserving heat for 1-3 hours, then heating to 400-500 ℃ at a heating rate of 4 ℃ per minute, preserving heat for 3-6 hours, controlling a cooling rate to 4-6 ℃ per minute until the temperature reaches room temperature, then vacuumizing, treating extracted residual fluorine gas and byproducts in the furnace with alkali liquor, and sieving with a 10-mesh screen to obtain the fluorinated graphene.
In one embodiment, the alloy balls are assisted by Monel alloy, the diameters of the alloy balls are 5 mm, 10 mm and 15 mm, the number ratio of the alloy balls with different diameters is 4:2:1, the mass ratio of the alloy balls to graphene is 10-20: 1, the rotating stirring paddle drives the alloy balls to turn over materials in fluorination, and the fluorination is more uniform and deeper into the materials due to dynamic change.
In one embodiment, theThe fluorine-carbon ratio of the fluorinated graphene is 0.8-1.1, and the material conductivity is 3 multiplied by 10-8To 9X 10-8Siemens per meter.
The following examples are provided to further illustrate the embodiments of the present invention and are not intended to limit the scope of the present invention.
Example one
In this embodiment, taking the preparation of a laminated fluorinated graphene with a fluorocarbon ratio of 1.06 and a surface C ═ C bond ratio of 20% as an example, the influence of the preparation method provided in this embodiment on the surface C ═ C bond ratio of the fluorinated graphene is verified through a specific test, specifically as follows:
(1) mixing and grinding multilayer graphene and polyvinyl alcohol according to the mass ratio of 2:1 for 10 minutes, mixing the mixture in deionized water according to the proportion of 15%, shearing and emulsifying the mixed solution at a high speed of 3000 r/min for 60 minutes, and then keeping the homogeneous solution at the pressure of 1200 pascals for 30 minutes by using a high-pressure homogenizer to obtain a homogeneous solution;
(2) and (3) placing the solution in the step (1) in a freeze dryer, freezing for 2 hours at-75 ℃, placing in a drying bin, vacuumizing to 1 Pa, drying until the water is completely removed, then placing the dried mixed powder in a tubular furnace, heating to 500 ℃ at the heating rate of 5 ℃ per minute, preserving the heat for 3 hours, and then cooling along with the furnace to obtain the laminated graphene. The protective gas of the tube furnace is argon, and the flow rate of the argon is kept at 100 standard milliliters per minute;
(3) putting the multilayer graphene obtained in the step (2) and Monel alloy balls with diameters of 5 mm, 10 mm and 15 mm into a fluorination furnace, wherein the number ratio of the Monel balls with different diameters is 4:2:1, the mass ratio of the alloy balls to the multilayer graphene is 15:1, sealing, vacuumizing, removing oxygen and water in a bin at 100 ℃ by using inert gas, and repeating for 3 times;
(4) turning on a stirring paddle at the rotating speed of 200 revolutions per minute, turning over the alloy balls and the multilayer graphene, introducing 20% fluorine/nitrogen mixed gas, controlling the pressure at 90 kilopascals, and operating for 30 minutes;
(5) and controlling the temperature in the furnace according to a set temperature rising program: heating to 180 ℃ at a heating rate of 2 ℃ per minute, preserving heat for 1 hour, heating to 500 ℃ at a heating rate of 4 ℃ per minute, preserving heat for 6 hours, controlling a cooling rate to 4 ℃ per minute until the temperature reaches room temperature, vacuumizing, treating the extracted residual fluorine gas and byproducts in the furnace with alkali liquor, and sieving with a 10-mesh sieve to obtain the laminated fluorinated graphene, wherein the shape of the material is shown in figure 1.
The method for preparing the lithium battery by using the fluorinated graphene prepared by the embodiment as the anode comprises the following steps: weighing laminated fluorinated graphene, conductive ketjen black and polyvinylidene fluoride in a ratio of 8:1:1 respectively; placing polyvinylidene fluoride in a small beaker, adding a certain amount of N-methyl pyrrolidone, and stirring to form a gel; uniformly mixing fluorinated graphene and conductive ketjen black, and slowly adding the mixture into a beaker; supplementing N-methylpyrrolidone to obtain uniformly dispersed slurry, coating the slurry on a carbon-coated aluminum foil in a thickness of 150 micrometers, and performing vacuum drying for 24 hours to obtain a pole piece; the counter electrode is metal lithium, the diaphragm is a celgard-2500 series glass fiber diaphragm, and the electrolyte is 1M LiBF4PC DME (1: 1); the electrochemical performance of the lithium battery is shown in fig. 3, and it can be seen that the rate performance of the lithium battery is excellent, the maximum discharge rate reaches 40C, and the discharge specific capacity is 542.1 milliampere hours/gram at the moment;
example two
In this embodiment, taking the preparation of a laminated fluorinated graphene with a fluorocarbon ratio of 1.04 and a surface C ═ C bond ratio of 12% as an example, the influence of the preparation method provided in this embodiment on the surface C ═ C bond ratio of the fluorinated graphene is verified through a specific test, specifically as follows:
in this example, compared with the first example, in the high-temperature fluorination assisted by the alloy spheres, the mass ratio of the alloy spheres to the multilayer graphene is adjusted from 15:1 to 10:1, and other experimental conditions are the same as those in the first example, so that the fluorine-carbon ratio of the prepared laminated fluorinated graphene is 1.04, and the ratio of surface C to C bond is 12%;
EXAMPLE III
In this embodiment, taking the preparation of a laminated fluorinated graphene with a fluorocarbon ratio of 1.07 and a surface C ═ C bond ratio of 15% as an example, the influence of the preparation method provided in this embodiment on the surface C ═ C bond ratio of the fluorinated graphene is verified through a specific test, specifically as follows:
in this embodiment, compared with the first embodiment, in the high-temperature fluorination assisted by the alloy spheres, the mass ratio of the alloy spheres to the multilayer graphene is adjusted from 15:1 to 20:1, and other experimental conditions are the same as those in the first embodiment, so that the fluorine-carbon ratio of the prepared laminated fluorinated graphene is 1.07, and the ratio of C to C bonds on the surface is 15%;
example four
In this embodiment, taking the preparation of a laminated fluorinated graphene with a fluorocarbon ratio of 1.04 and a surface C ═ C bond ratio of 16% as an example, the influence of the preparation method provided in this embodiment on the surface C ═ C bond ratio of the fluorinated graphene is verified through a specific test, specifically as follows:
in this embodiment, compared with the first embodiment, in the high-temperature fluorination process, the rotation speed of the stirring paddle is adjusted from 200 rpm to 100 rpm, and other experimental conditions are the same as those in the first embodiment, so that the fluorine-carbon ratio of the prepared laminated fluorinated graphene is 1.04, and the ratio of C to C bonds on the surface is 16%;
EXAMPLE five
In this embodiment, taking the preparation of a laminated fluorinated graphene with a fluorocarbon ratio of 1.06 and a surface C ═ C bond ratio of 18% as an example, the influence of the preparation method provided in this embodiment on the surface C ═ C bond ratio of the fluorinated graphene is verified through a specific test, specifically as follows:
in this embodiment, compared with the first embodiment, in the high temperature fluorination process, the rotation speed of the stirring paddle is adjusted from 200 rpm to 300 rpm, and other experimental conditions are the same as those in the first embodiment, so that the fluorine-carbon ratio of the prepared laminated fluorinated graphene is 1.06, and the surface C ═ C bond ratio is 18%;
EXAMPLE six
In this embodiment, taking the preparation of a laminated fluorinated graphene with a fluorocarbon ratio of 0.89 and a surface C ═ C bond ratio of 16% as an example, the influence of the preparation method provided in this embodiment on the surface C ═ C bond ratio of the fluorinated graphene is verified through a specific test, specifically as follows:
in this embodiment, compared to the first embodiment, in the high temperature fluorination process, the fluorination temperature is adjusted from 500 ℃ to 400 ℃, other experimental conditions are the same as those in the first embodiment, the fluorocarbon ratio of the prepared laminated fluorinated graphene is 0.89, and the ratio of C to C bonds on the surface is 16%;
EXAMPLE seven
In this embodiment, taking the preparation of a laminated fluorinated graphene with a fluorocarbon ratio of 0.96 and a surface C ═ C bond ratio of 17% as an example, the influence of the preparation method provided in this embodiment on the surface C ═ C bond ratio of the fluorinated graphene is verified through a specific test, specifically as follows:
in this embodiment, compared with the first embodiment, in the high-temperature fluorination process, the fluorination temperature is adjusted from 500 ℃ to 450 ℃, other experimental conditions are the same as those in the first embodiment, the fluorine-carbon ratio of the prepared laminated fluorinated graphene is 0.96, and the ratio of C-C bonds on the surface is 17%;
example eight
In this embodiment, taking the preparation of a laminated fluorinated graphene with a fluorocarbon ratio of 0.8 and a surface C ═ C bond ratio of 14% as an example, the influence of the preparation method provided in this embodiment on the surface C ═ C bond ratio of the fluorinated graphene is verified through a specific test, specifically as follows:
in this embodiment, compared with the first embodiment, in the high temperature fluorination process, the temperature holding time at 500 ℃ is adjusted from 6 hours to 3 hours, and other experimental conditions are the same as those in the first embodiment, so that the fluorine-carbon ratio of the prepared laminated fluorinated graphene is 0.8, and the ratio of C to C bonds on the surface is 14%;
comparative example 1
In this comparative example, taking the preparation of a laminated fluorinated graphene with a fluorocarbon ratio of 1.05 and a surface C ═ C bond ratio of 4% as an example, the influence of the preparation method provided in this comparative example on the surface C ═ C bond ratio of the fluorinated graphene is verified through specific tests, specifically as follows:
compared with the first embodiment, in the high-temperature fluorination process, the assistance of alloy balls and stirring paddles is cancelled, the material is placed on the surface of an object carrying plate and is independently placed into a fluorination furnace for fluorination, other experimental conditions are the same as those in the first embodiment, the fluorination mode is a conventional fluorination mode, the fluorine-carbon ratio of the prepared laminated fluorinated graphene is 1.05, and the proportion of C-C bonds on the surface of the laminated fluorinated graphene is 4%;
comparative example No. two
In this comparative example, taking the preparation of a laminated fluorinated graphene with a fluorocarbon ratio of 1.06 and a surface C ═ C bond ratio of 5% as an example, the influence of the preparation method provided in this comparative example on the surface C ═ C bond ratio of the fluorinated graphene is verified through specific tests, specifically as follows:
compared with the first embodiment, in the high-temperature fluorination process, the addition of alloy balls is cancelled, only the rotation of a stirring paddle is used as an auxiliary, other experimental conditions are the same as those of the first embodiment, the fluorination mode is a conventional fluorination mode, the fluorine-carbon ratio of the prepared laminated fluorinated graphene is 1.06, and the proportion of C bonds on the surface is 5%;
comparative example No. three
In this comparative example, taking the preparation of a laminated fluorinated graphene with a fluorocarbon ratio of 1.05 and a surface C ═ C bond ratio of 8% as an example, the influence of the preparation method provided in this comparative example on the surface C ═ C bond ratio of the fluorinated graphene is verified through specific tests, specifically as follows:
compared with the first embodiment, in the high-temperature fluorination process, the mass ratio of the alloy spheres to the multilayer graphene is excessively adjusted to 40:1, the fluorine-carbon ratio of the prepared laminated fluorinated graphene is 1.05, and the surface C-C bond ratio is 8%;
comparative example No. four
In this comparative example, taking a laminated graphene fluoride with a fluorocarbon ratio of 1.05 and a surface C ═ C bond ratio of 12% as an example, the influence of the preparation method provided in this example on the surface C ═ C bond ratio of the graphene fluoride is verified through specific tests, specifically as follows:
compared with the first embodiment, in the pretreatment of the multilayer graphene, a stabilizer is not used, the prepared fluorinated graphene has the morphology shown in fig. 4, and is a multilayer fluorinated graphene, but the number of layers is greatly reduced compared with that of the first embodiment, the fluorocarbon ratio is 1.05, and the ratio of surface C to C bonds is 12%;
when the lithium battery is prepared by using the fluorinated graphene in the comparative example as the positive electrode and the lithium battery preparation method in the first example, the maximum discharge rate of the battery reaches 15C, and the discharge specific capacity is 614.5 mAmp hours/g.
Comparative example five
In the comparative example, a few-layer fluorinated graphene with a fluorocarbon ratio of 0.95 and a surface C ═ C bond ratio of 5% is used as a positive electrode material, the morphology of the few-layer fluorinated graphene is shown in fig. 5, the lithium battery is prepared by the lithium battery preparation method in the first example, the electrochemical performance of the battery is shown in fig. 6, the maximum discharge rate reaches 10C, and the discharge specific capacity is 380.6 milliampere hours/gram at the moment;
referring to table 1, a summary of a comparison of all examples of the invention with comparative examples, it can be seen that:
1) in example 1, when the mass ratio of the alloy ball to the graphene is 15:1, and the rotation speed of the stirring paddle is 200 rpm, the multi-layer cake-shaped fluorinated graphene with high fluorocarbon ratio and highest C-C bond ratio can be obtained by fluorination for 6 hours at 500 ℃;
2) the comparison of examples 1, 2 and 3 can obtain the alloy ball/graphite mass ratio, which directly affects the ratio of C ═ C bond in the final fluorinated graphene, 15:1 is the optimal ratio, and the excessively high mass ratio in comparative example 3 controls the size of the graphite sheet to be too small, so that the material loss in the fluorination process is serious, and the C ═ C bond is difficult to retain;
3) through comparison among examples 1, 4 and 5, the relative movement speed of the alloy balls and graphene is influenced by changing the rotating speed of the stirring paddle, and the result shows that the rotating speed has small influence on the ratio of C to C bonds, and the optimal rotating speed of 200 rpm/min in example 1 can be obtained. From example 1 and comparative examples 1, 2, it can be concluded that the addition of alloy balls assisted by high temperature fluorination can retain a high proportion of C ═ C bonds;
4) from comparative example 1, which is a conventional high temperature fluorination, it can be seen that the product has a very low C ═ C bond ratio, and in conjunction with examples 1, 6, 7, 8, suitable fluorination temperatures and incubation times were determined to be 500 degrees celsius and 6 hours.
TABLE 1
Referring to table 2, for comparison of electrochemical performance of the lithium batteries of example 1 and comparative examples 4 and 5, it can be seen that:
1) the laminated fluorinated graphene in the embodiment 1 benefits from a graphene structure stacked layer by layer to provide a large number of active sites for electrochemical reaction, and meanwhile, the conductivity of the material is greatly improved by a high proportion of C (carbon) bonds on the surface, and under the combined action of two points, the laminated fluorinated graphene shows excellent rate performance in a lithium battery, the highest discharge rate reaches 40C, and meanwhile, the specific capacity is 542.1 mAmp/g, which is the best rate performance in all the prior art;
2) comparative example 4 is a preparation method of the present invention without adding a stabilizer, because of lack of adhesion and buffering of the stabilizer, the number of layers of the obtained multilayer fluorinated graphene is greatly reduced compared to the number of layers of the laminated fluorinated graphene in example 1, but the multilayer structure and the surface of the multilayer fluorinated graphene retain C ═ C bonds, so that the multilayer fluorinated graphene still has a higher rate capability, the maximum discharge rate can reach 15C, and the specific capacity is 614.5 ma hour/g;
3) in comparative example 5, a battery was assembled using a few layers of fluorinated graphene as a positive electrode material, and the maximum discharge rate was 10C, while the specific capacity was 380.6 ma-hr/g. In comparative examples 1 and 2, it can be demonstrated that the laminated structure actually promotes the electrochemical reaction in the battery, and that the ratio of C ═ C bonds on the surface of the material also has an important influence on the rate capability of the battery.
TABLE 2
In summary, compared with the prior art that a large amount of fluorine reacts on the surface of a material, so that the C ═ C bonds on the surface are destroyed and a large amount of carbon-fluorine bonds are generated, embodiments of the present invention provide a preparation method of a laminated fluorinated graphene, wherein a mixed solution of a multi-layer graphene and a stabilizer is subjected to shear emulsification, homogenization, freeze drying and annealing, and then an alloy ball assisted high-temperature fluorination method is performed to obtain the fluorinated graphene; on one hand, the fluorinated graphene has a laminated sheet stacking structure, so that more reaction sites can be provided; on the other hand, 10-20% of C ═ C bonds are reserved on the surface of the material, and the conductivity of the material is improved.
In addition, the laminated fluorinated graphene with high fluorocarbon ratio and high conductivity is applied to the lithium battery cathode material, so that the high-power lithium/fluorinated graphene battery with the discharge rate as high as 40C is obtained.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, and improvement made within the spirit and scope of the present invention are included in the protection scope of the present invention.
Claims (4)
1. A preparation method of laminated fluorinated graphene for a positive electrode of a lithium battery is characterized by comprising the following steps:
shearing, emulsifying, homogenizing, freeze-drying and annealing the mixed solution of the N-layer graphene and the stabilizing agent to obtain laminated graphene; wherein N is more than or equal to 3 and less than or equal to 10, and is a positive integer; the stabilizer is polyvinyl alcohol, and the mass ratio of the graphene to the polyvinyl alcohol is 1-2: 1;
carrying out high-temperature fluorination on the laminated graphene under the assistance of alloy balls to obtain laminated fluorinated graphene; the relative content of C = C bonds in all carbon-containing chemical bonds on the surface of the laminated fluorinated graphene is 10-20%.
2. The method for producing the positive electrode laminated fluorinated graphene for a lithium battery according to claim 1, further comprising:
(1) mixing and grinding multi-layer graphene and polyvinyl alcohol according to a mass ratio of 1-2: 1 for 10 minutes, mixing the mixture in deionized water according to a proportion of 10-20%, shearing and emulsifying the mixed solution at a high speed of 2000-4000 rpm for 30-90 minutes, and then maintaining the homogeneous solution for 30-60 minutes under the pressure of 1000-1500 pascals through a high-pressure homogenizer to obtain a homogeneous solution;
(2) placing the solution in the step (1) in a freeze dryer, freezing for 2 hours at-75 ℃ in a freezing chamber, placing in a drying chamber, vacuumizing to 1 Pa, drying until the moisture is completely removed, then placing the dried mixed powder in a tubular furnace, heating to 500 ℃ at the heating rate of 5 ℃ per minute, preserving the heat for 3 hours, cooling along with the furnace to obtain laminated graphene, wherein the protective gas of the tubular furnace is argon, and the flow of the argon is kept at 100 standard milliliters per minute;
(3) adding the graphene obtained in the step (2) and alloy balls with different sizes and proportions into a fluorination furnace with a stirring paddle, sealing, vacuumizing, removing oxygen and water in a bin by using inert gas at 100 ℃, and repeating for 3 times;
(4) turning on a stirring paddle at a rotating speed of 100-300 revolutions per minute, turning over the alloy ball and the graphene, switching and introducing fluorine/nitrogen mixed gas with a fluorine gas volume fraction of 20%, controlling the pressure at 80-90 kPa, and operating for 30 minutes;
(5) controlling the temperature in the furnace, firstly heating to 180 ℃ at a heating rate of 2 ℃ per minute, preserving heat for 1-3 hours, then heating to 400-500 ℃ at a heating rate of 4 ℃ per minute, preserving heat for 3-6 hours, controlling a cooling rate to 4-6 ℃ per minute until the temperature reaches room temperature, then vacuumizing, treating extracted residual fluorine gas and byproducts in the furnace with alkali liquor, and sieving with a 10-mesh screen to obtain the fluorinated graphene.
3. The method for preparing the laminated fluorinated graphene as the positive electrode of the lithium battery as claimed in claim 1, wherein the alloy spheres are obtained by processing Monel alloy, the diameters of the alloy spheres are 5 mm, 10 mm and 15 mm, the number ratio of the alloy spheres with different diameters is 4:2:1, and the mass ratio of the alloy spheres to the graphene is 10-20: 1.
4. The method for preparing the graphene fluoride laminated on the positive electrode of the lithium battery as claimed in claim 1, wherein the graphene fluoride has a fluorine-carbon ratio of 0.8 to 1.1 and an electrical conductivity of 3 x 10-8To 9X 10-8The Siemens/m range, the size distribution is 2-25 microns.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011555033.4A CN112661146B (en) | 2020-12-23 | 2020-12-23 | Preparation method of laminated fluorinated graphene for positive electrode of lithium battery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011555033.4A CN112661146B (en) | 2020-12-23 | 2020-12-23 | Preparation method of laminated fluorinated graphene for positive electrode of lithium battery |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN112661146A CN112661146A (en) | 2021-04-16 |
| CN112661146B true CN112661146B (en) | 2022-07-05 |
Family
ID=75408583
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011555033.4A Active CN112661146B (en) | 2020-12-23 | 2020-12-23 | Preparation method of laminated fluorinated graphene for positive electrode of lithium battery |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112661146B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114628631B (en) * | 2022-03-07 | 2023-09-19 | 湘潭大学 | Preparation method of high-capacity alkali metal-carbon fluoride secondary battery |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105271199A (en) * | 2015-11-05 | 2016-01-27 | 湖北卓熙氟化股份有限公司 | Preparation method of fluorinated graphene |
| US9437372B1 (en) * | 2016-01-11 | 2016-09-06 | Nanotek Instruments, Inc. | Process for producing graphene foam supercapacitor electrode |
| CN106654204A (en) * | 2016-12-15 | 2017-05-10 | 中国航空工业集团公司北京航空材料研究院 | Preparation method for graphene conductive slurry |
| WO2017116657A1 (en) * | 2015-12-28 | 2017-07-06 | Nanotek Instruments, Inc. | Graphene-Carbon Hybrid Foam |
| WO2017174043A2 (en) * | 2016-04-07 | 2017-10-12 | 张麟德 | Fluorinated graphene and preparation method therefor |
| CN207811274U (en) * | 2017-12-08 | 2018-09-04 | 常州第六元素材料科技股份有限公司 | A kind of equipment preparing graphene particles |
| CN109179395A (en) * | 2018-10-23 | 2019-01-11 | 湖北工程学院 | A kind of fluorinated graphene and preparation method thereof, application |
| CN111620326A (en) * | 2020-04-27 | 2020-09-04 | 福建江夏学院 | Preparation method of fluorinated graphene material with adjustable fluorine content |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9809459B2 (en) * | 2015-09-23 | 2017-11-07 | Nanotek Instruments, Inc. | Process for producing monolithic film of integrated highly oriented halogenated graphene sheets or molecules |
| US11111150B2 (en) * | 2018-09-10 | 2021-09-07 | Board Of Regents, The University Of Texas System | Facile direct functionalization of pristine graphene nanoparticles |
-
2020
- 2020-12-23 CN CN202011555033.4A patent/CN112661146B/en active Active
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105271199A (en) * | 2015-11-05 | 2016-01-27 | 湖北卓熙氟化股份有限公司 | Preparation method of fluorinated graphene |
| WO2017116657A1 (en) * | 2015-12-28 | 2017-07-06 | Nanotek Instruments, Inc. | Graphene-Carbon Hybrid Foam |
| US9437372B1 (en) * | 2016-01-11 | 2016-09-06 | Nanotek Instruments, Inc. | Process for producing graphene foam supercapacitor electrode |
| WO2017174043A2 (en) * | 2016-04-07 | 2017-10-12 | 张麟德 | Fluorinated graphene and preparation method therefor |
| CN106654204A (en) * | 2016-12-15 | 2017-05-10 | 中国航空工业集团公司北京航空材料研究院 | Preparation method for graphene conductive slurry |
| CN207811274U (en) * | 2017-12-08 | 2018-09-04 | 常州第六元素材料科技股份有限公司 | A kind of equipment preparing graphene particles |
| CN109179395A (en) * | 2018-10-23 | 2019-01-11 | 湖北工程学院 | A kind of fluorinated graphene and preparation method thereof, application |
| CN111620326A (en) * | 2020-04-27 | 2020-09-04 | 福建江夏学院 | Preparation method of fluorinated graphene material with adjustable fluorine content |
Non-Patent Citations (1)
| Title |
|---|
| Edge-Fluorinated Graphene Nanoplatelets as High Performance Electrodes for Dye-Sensitized Solar Cells and Lithium Ion Batteries;In-Yup Jeon，et al.;《Advanced Functional Materials》;20150108;第1170-1179页 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN112661146A (en) | 2021-04-16 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111276679A (en) | Double-carbon composite molybdenum sulfide composite material for sodium ion battery cathode material and preparation method thereof | |
| CN109256544B (en) | Lithium-silicon battery electrode material and preparation method thereof, and lithium-silicon battery | |
| CN109713302A (en) | Under a kind of ultralow temperature can big multiplying power charge and discharge lithium ion battery and preparation method thereof | |
| CN112661146B (en) | Preparation method of laminated fluorinated graphene for positive electrode of lithium battery | |
| CN113823781A (en) | Composite negative electrode material and preparation method thereof | |
| CN112670528B (en) | Preparation method of high-rate primary alkali metal battery | |
| Ouyang et al. | Tuning composite solid-state electrolyte interface to improve the electrochemical performance of lithium-oxygen battery | |
| CN112794310B (en) | Potassium ion battery anode material and preparation method and application thereof | |
| CN111725492B (en) | Carbon/lithium titanate composite material and preparation method thereof | |
| CN108117056A (en) | The preparation method of graphene coated plasma modification carbonaceous mesophase spherules | |
| CN112687873B (en) | Preparation method of high-specific-energy lithium battery | |
| GB2621289A (en) | Method for preparing silicon-carbon composite negative electrode material and use thereof | |
| CN108987732B (en) | SiO composite cathode material of lithium ion battery and preparation method thereof | |
| CN110600742A (en) | Preparation method and application of graphene conductive slurry | |
| CN112687856B (en) | Preparation method of high-power lithium battery | |
| CN114899405A (en) | Cr (chromium) 8 O 21 Preparation method of/C modified carbon fluoride anode material | |
| CN115548286A (en) | Coated modified lithium iron phosphate composite material, and preparation method and application thereof | |
| CN112723350B (en) | Preparation method of lithium battery positive electrode flower-like fluorinated graphene | |
| CN115172743A (en) | Graphite modified material, graphite-based negative electrode active material, and preparation method and application thereof | |
| CN114464784A (en) | Three-dimensional coated silicon-based negative electrode material and preparation method thereof | |
| CN113675385A (en) | Nanoscale silicon-carbon composite negative electrode material, preparation method and lithium ion battery | |
| CN111924848A (en) | Silicon-based negative electrode material for lithium ion battery and preparation method thereof | |
| CN112678800B (en) | Preparation method of graphite fluoride micron sheet | |
| CN114888282B (en) | A, A 2 B 7 Fluorination modification method of hydrogen storage alloy, obtained fluorination modified hydrogen storage alloy and application thereof | |
| CN113461015B (en) | Preparation method of nitrogen-doped carbon-coated porous silicon |
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 | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |