Lithium carbon fluoride battery positive plate as well as preparation method and application thereof

Abstract

The invention relates to the technical field of batteries, in particular to a lithium carbon fluoride battery positive plate as well as a preparation method and application thereof. The method comprises the following steps: placing graphite in a fluorination reactor, filling a fluorination gas source, and carrying out fluorination reaction to obtain graphite fluoride; when the pressure in the fluorination reactor exceeds 200kPa, the pressure release valve is opened, and the fluorination gas source enters the cooler to be cooled and then enters the gas circulating pump to circulate and flow back to the fluorination reactor. According to the invention, a gas source flowing method is utilized, and the fluorination reaction is carried out safely and stably by accurately controlling the gas flow and taking away part of reaction heat, so that the potential safety hazard of chamber explosion caused by overheat reaction in the fluorination process is solved. Uniformly mixing graphite fluoride, a conductive agent, a binder and a solvent to obtain positive electrode slurry; and coating a current collector with the positive electrode slurry, drying, and rolling to obtain the positive electrode plate of the lithium carbon fluoride battery, which has excellent electrochemical performance.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and particularly to a positive electrode sheet of a lithium carbon fluoride battery, a preparation method thereof, and an application thereof. Background Art

[0002] A lithium carbon fluoride battery (Li / CFx) is a primary battery with carbon fluoride as the positive electrode and metallic lithium as the negative electrode, and is a new generation of lightweight battery with the highest specific energy among current primary batteries. At the same time, due to the extremely low self-discharge performance, excellent storage performance, wide operating temperature range, and environmental friendliness of this type of battery, it is widely used in cutting-edge technology fields such as national defense, aerospace, and medical implants.

[0003] The key electrode material in a lithium carbon fluoride battery is carbon fluoride. The preparation methods of carbon fluoride mainly include high-temperature gas-phase fluorination, low-temperature fluorination, plasma method, and electrolytic synthesis method, etc. The currently industrialized method is high-temperature gas-phase fluorination, and the commonly used carbon material is graphite material. Graphite fluoride is prepared through high-temperature gas-phase fluorination. The reaction furnace is mostly a static reaction furnace, and the gas flow rate is not precisely controlled. In this method, since the reaction process is a gas-solid reaction and is an exothermic reaction, once the reaction is too intense, it will cause an instantaneous increase in pressure and temperature, resulting in a furnace explosion accident, with great potential safety hazards.

[0004] In addition, due to the poor conductivity, low surface energy, and poor electrolyte permeability of carbon fluoride materials, when carbon fluoride materials are used as the electrode materials of lithium primary batteries, polarization is likely to occur, resulting in poor rate performance of lithium carbon fluoride batteries and inability to meet the requirements of high-power discharge.

[0005] Therefore, we propose a positive electrode sheet of a lithium carbon fluoride battery, a preparation method thereof, and an application thereof. Summary of the Invention

[0006] The purpose of the present invention is to provide a positive electrode sheet of a lithium carbon fluoride battery, a preparation method thereof, and an application thereof, so as to solve the problems raised in the prior art.

[0007] To achieve the above-mentioned invention purpose, the present invention provides the following technical solutions: A preparation method of graphite fluoride, comprising the following steps: Place graphite in a fluorination reactor 2, charge a fluorination gas source 1, control the pressure in the fluorination reactor 2 to be 100 - 150 kPa, and carry out a fluorination reaction to obtain graphite fluoride; when the pressure in the fluorination reactor 2 exceeds 200 kPa, open a pressure relief valve 3, the fluorination gas source enters a cooler 4 for cooling, and then enters a gas circulation pump 5 for circulating back to the fluorination reactor 2.

[0008] Further, the fluorination gas source 1 is one or more of F2, ClF, ClF3, and NF3.

[0009] Further, the reaction conditions of the fluorination reactor 2 are as follows: reaction temperature is 300 - 500 °C, and reaction time is 5 - 30 h.

[0010] Further, the gas circulation pump 5 controls the gas flow rate to be 0.5 - 1.0 m 3 / h.

[0011] Further, the fluorine - carbon ratio of the fluorinated graphite is 0.5 - 0.9.

[0012] In the above - mentioned technical solution, the gas circulation pump has a sealed structure. When it is not opened, it can only let in but not out, and it is equipped with flow control, which can accurately control the flow rate. The gas flow rate is controlled at 0.5 - 1.0 m 3 / h. If the flow rate is too low, the reaction heat cannot be carried away, and if the flow rate is too high, excessive heat is easily carried away, resulting in insufficient fluorination reaction.

[0013] A method for preparing a positive electrode sheet of a lithium - carbon fluoride battery, characterized in that it includes the following steps: Step S1: Mix the fluorinated graphite, conductive agent, binder, and solvent described in claim 5 evenly to obtain a positive electrode paste; Step S2: Coat the positive electrode paste on a current collector, dry it, and then roll - press it to obtain a positive electrode sheet of a lithium - carbon fluoride battery.

[0014] Further, the mass ratio of the fluorinated graphite, conductive agent, and binder is (80 - 95):(2 - 10):(3 - 10).

[0015] Further, the fluorinated graphite is subjected to a modification treatment, and the specific process is as follows: Step (1): Perform mixed - plasma treatment on the fluorinated graphite to obtain pretreated fluorinated graphite; Step (2): Heat the polyvinyl alcohol solution to 70 - 80 °C, add sodium hydroxide solution to adjust the pH to 9 - 10, add 2,3 - epoxypropyltrimethylammonium chloride, react for 4 - 6 h, cool to room temperature, and adjust the pH to neutral to obtain a modified polyvinyl alcohol solution; Step (3): Mix the modified polyvinyl alcohol solution and 6 - aminoquinoline evenly, introduce nitrogen, add isocyanatoethyl methacrylate and dibutyltin dilaurate, react at 65 - 75 °C for 6 - 8 h, cool to room temperature, and add deionized water to obtain solution A; Step (4): Mix solution A and pretreated fluorinated graphite evenly, introduce nitrogen, add 3,4 - ethylenedioxythiophene, adjust the pH of the system to 2 - 3 with hydrochloric acid, dropwise add ammonium persulfate, finish dropping in 30 - 50 min, react under ice - water bath conditions for 22 - 24 h, and after centrifugation, washing, and drying, obtain modified fluorinated graphite.

[0016] Further, in the step (1), the process conditions for plasma treatment are as follows: the working atmosphere is C2H2 / Ar, C2H2:Ar = 1:(1 - 2), the treatment time is 10 - 20 min, the treatment power is 200 - 250 W, the vacuum degree is 15 - 40 Pa, and the treatment temperature is 25 - 300 °C.

[0017] Further, in the step (2), the mass of 3 - glycidyltrimethylammonium chloride is 10 - 20% of the mass of the polyvinyl alcohol solution.

[0018] Further, in the step (3), the mass ratio of the modified polyvinyl alcohol solution to 6 - aminoquinoline is 1:(0.1 - 0.2).

[0019] Further, in the step (3), the mass of isocyanatoethyl methacrylate is 2 - 3 times the mass of 6 - aminoquinoline.

[0020] Further, in the step (3), the mass ratio of isocyanatoethyl methacrylate to dibutyltin dilaurate is 1:(0.01 - 0.03).

[0021] Further, in the step (3), the solid content of solution A is 20%.

[0022] Further, in the step (4), the mass ratio of solution A to the pretreated fluorinated graphite is 1:(0.05 - 0.10).

[0023] Further, in the step (4), the mass of 3,4 - ethylenedioxythiophene is 1 - 2 times the mass of the fluorinated graphite.

[0024] Further, in the step (4), the mass of ammonium persulfate is 3 - 5% of the mass of 3,4 - ethylenedioxythiophene.

[0025] In the above technical solution, C2H2 / Ar mixed plasma is used to modify fluorinated graphite, thinning the high-fluorine layer on the surface of the carbon fluoride material, increasing the surface carbon content, increasing the semi-ionic carbon-fluorine bonds with high electrochemical activity, reducing the bond energy of the carbon-fluorine bond, and improving the rate performance of the battery; polyvinyl alcohol (PVA) is a hydrophilic substance containing a large number of hydrogen bonds in the molecular chain, with good water solubility, mechanical properties, film-forming properties and biodegradability. Polyvinyl alcohol is modified with 3-glycidyltrimethylammonium chloride to introduce quaternary ammonium salt groups on the side chain of PVA, and then 6-aminoquinoline and the modified polyvinyl alcohol solution are mixed evenly. Subsequently, under the action of dibutyltin dilaurate catalyst, it continues to react with isocyanatoethyl methacrylate to introduce quinoline groups and double bonds, which can react with 3,4-ethylenedioxythiophene conductive polymer monomers to introduce thiophene groups. A coating layer with a network structure is formed on the surface of fluorinated graphite through a polymerization reaction, which can further improve the structural stability of the positive electrode material.

[0026] Further, the conductive agent is at least one of conductive graphite, conductive carbon black, carbon nanotubes and graphene.

[0027] Further, the binder is polyvinylidene fluoride.

[0028] Further, the solid content of the positive electrode slurry is 50-70%.

[0029] Further, the solvent is N-methylpyrrolidone.

[0030] Further, the current collector is aluminum foil.

[0031] Further, the thickness of the positive electrode sheet is 100-200 μm.

[0032] Compared with the prior art, the beneficial effects of the present invention are: 1. For a positive electrode sheet of a lithium carbon fluoride battery, its preparation method and application of the present invention, by using the method of gas source flow itself, through precise control of the gas flow rate, part of the reaction heat is taken away, enabling the fluorination reaction to proceed safely and stably, thus solving the safety hazard of chamber explosion caused by overheating during the fluorination process.

[0033] 2. A positive electrode sheet of a lithium carbon fluoride battery, its preparation method and application according to the present invention reduce the high-fluorine layer on the surface of the carbon fluoride material through plasma, increase the surface carbon content, increase the semi-ionic carbon-fluorine bonds with high electrochemical activity, reduce the bond energy of the carbon-fluorine bonds, and improve the rate performance of the battery; 3-glycidyltrimethylammonium chloride is used to modify polyvinyl alcohol, and quaternary ammonium salt groups are introduced on the side chain of PVA to obtain a modified polyvinyl alcohol solution. Then, 6-aminoquinoline and the modified polyvinyl alcohol solution are mixed evenly, and then, under the action of dibutyltin dilaurate catalyst, it continues to react with isocyanatoethyl methacrylate to introduce quinoline groups and double bonds, which can react with 3,4-ethylenedioxythiophene conductive polymer monomers to introduce thiophene groups, thereby forming a coating layer with a network structure on the surface of the fluorinated graphite, improving the coating uniformity, and greatly improving the structural stability of the positive electrode material; among them, quinoline and quaternary ammonium salt have dual electron and ion conduction capabilities, which can effectively improve the rate and cycle performance of the battery. The presence of thiophene groups can improve the conductivity of the material and promote the transmission of electrons in the electrode, thereby further improving the overall performance of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the present invention and do not constitute a limitation to the present invention. In the drawings: Figure 1 is a process schematic diagram of the present invention; In the figure: 1 is a fluorine gas source, 2 is a fluorination reactor, 3 is a pressure relief valve, 4 is a cooler, and 5 is a gas circulation pump. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0036] It should be noted that there are no special restrictions on the purchase manufacturers of all raw materials involved in the present invention. Exemplarily, they include: graphite: particle size of 5-10 μm, sourced from Luoyang Tongrun Information Technology Co., Ltd.; current collector: aluminum foil, 12 μm thick, grade H18-1100, sourced from Shenzhen Honglei Metal Materials Co., Ltd.; conductive agent: conductive carbon black SUPER P Li (TIMCAL), sourced from Guangdong Luwei New Materials Technology Co., Ltd.; binder: polyvinylidene fluoride, grade KF7200 of Japan's Kureha, sourced from Shanghai Huahenghui New Materials Technology Co., Ltd.; polyvinyl alcohol solution: grade 205 of Japan's Kuraray, solid content of 20%.

[0037] Example 1: A preparation method of fluorinated graphite, comprising the following processes: Place graphite in a fluorination reactor, fill it with F2, control the pressure in the fluorination reactor 2 to be 100 kPa, and carry out a fluorination reaction (reaction temperature 300 °C, reaction time 30 h) to obtain fluorinated graphite; when the pressure in the fluorination reactor exceeds 200 kPa, open the pressure relief valve, the fluorination gas source enters the cooler for cooling, and then enters the gas circulation pump to circulate back to the fluorination reactor. The gas circulation pump controls the gas flow rate to be 0.5 m 3 / h; A preparation method of a positive electrode sheet for a lithium carbon fluoride battery, comprising the following processes: Step S1: Mix 160 g of fluorinated graphite, 4 g of conductive agent, 6 g of binder and N-methylpyrrolidone evenly to obtain a positive electrode slurry with a solid content of 50%; Step S2: Coat the positive electrode slurry on the current collector, dry it and then roll it to obtain a positive electrode sheet for a lithium carbon fluoride battery.

[0038] Example 2: A preparation method of fluorinated graphite, comprising the following steps: Place graphite in a fluorination reactor, fill it with F2, control the pressure in the fluorination reactor 2 to be 120 kPa, and carry out a fluorination reaction (reaction temperature 400 °C, reaction time 10 h) to obtain fluorinated graphite; when the pressure in the fluorination reactor exceeds 200 kPa, open the pressure relief valve, the fluorination gas source enters the cooler for cooling, and then enters the gas circulation pump to circulate back to the fluorination reactor. The gas circulation pump controls the gas flow rate to be 0.6 m 3 / h; A preparation method of a positive electrode sheet for a lithium carbon fluoride battery, comprising the following processes: Step S1: Mix 170 g of fluorinated graphite, 10 g of conductive agent, 10 g of binder and N-methylpyrrolidone evenly to obtain a positive electrode slurry with a solid content of 55%; Step S2: Coat the positive electrode slurry on the current collector, dry it and then roll it to obtain a positive electrode sheet for a lithium carbon fluoride battery; The fluorinated graphite is subjected to a modification treatment, and the specific process is as follows: Step (1): Carry out a mixed plasma treatment on the fluorinated graphite (the process conditions for the plasma treatment are: the working atmosphere is C2H2 / Ar, C2H2:Ar = 1:1, the treatment time is 10 min, the treatment power is 200 W, the vacuum degree is 15 Pa, and the treatment temperature is 25 °C) to obtain pretreated fluorinated graphite; Step (2): Heat 3400 g of polyvinyl alcohol solution to 70 °C, add sodium hydroxide solution to adjust the pH to 9, add 340 g of 2,3-epoxypropyltrimethylammonium chloride, react for 4 h, cool to room temperature, and adjust the pH to neutral to obtain a modified polyvinyl alcohol solution; Step (3): Mix 3400 g of the modified polyvinyl alcohol solution and 340 g of 6-aminoquinoline evenly, react for 3 h, introduce nitrogen, add 680 g of isocyanatoethyl methacrylate and 6.8 g of dibutyltin dilaurate, react at 65 °C for 6 h, cool to room temperature, and add deionized water to obtain solution A with a solid content of 20%; Step (4): Mix 3400 g of solution A and 170 g of pretreated fluorinated graphite evenly, add 170 g of 3,4-ethylenedioxythiophene, use 1 mol / L hydrochloric acid to adjust the system pH to 2, dropwise add 5.1 g of ammonium persulfate, finish dropping in 30 min, react under ice-water bath conditions for 22 h, and obtain modified fluorinated graphite after centrifugation, washing, and drying.

[0039] Example 3: A preparation method of fluorinated graphite, comprising the following steps: Place graphite in a fluorination reactor, fill with F2, control the pressure in the fluorination reactor 2 to be 130 kPa, and carry out a fluorination reaction (reaction temperature 450 °C, reaction time 20 h) to obtain fluorinated graphite; when the pressure in the fluorination reactor exceeds 200 kPa, open the pressure relief valve, the fluorination gas source enters the cooler for cooling, and then enters the gas circulation pump for circulating back to the fluorination reactor, and the gas circulation pump controls the gas flow rate to be 0.8 m 3 / h; A preparation method of a lithium carbon fluoride battery positive electrode sheet, comprising the following processes: Step S1: Mix 180 g of fluorinated graphite, 14 g of conductive agent, 16 g of binder and N-methylpyrrolidone evenly to obtain a positive electrode slurry with a solid content of 60%; Step S2: Coat the positive electrode slurry on a current collector, dry it and then roll it to obtain a lithium carbon fluoride battery positive electrode sheet; The fluorinated graphite is subjected to a modification treatment, and the specific process is as follows: Step (1): Carry out mixed plasma treatment on the fluorinated graphite (the process conditions of the plasma treatment are: the working atmosphere is C2H2 / Ar, C2H2:Ar = 1:1.5, the treatment time is 15 min, the treatment power is 220 W, the vacuum degree is 30 Pa, and the treatment temperature is 100 °C) to obtain pretreated fluorinated graphite; Step (2): Heat 2250 g of polyvinyl alcohol solution to 75 °C, add sodium hydroxide solution to adjust the pH to 9.5, add 337 g of 2,3-epoxypropyltrimethylammonium chloride, react for 5 h, cool to room temperature, and adjust the pH to neutral to obtain a modified polyvinyl alcohol solution; Step (3): Mix 2250 g of the modified polyvinyl alcohol solution and 340 g of 6-aminoquinoline evenly, react for 4 h, introduce nitrogen gas, add 850 g of isocyanatoethyl methacrylate and 17 g of dibutyltin dilaurate, and react at 70 °C for 7 h. Cool to room temperature, add deionized water to obtain solution A with a solid content of 20%. Step (4): Mix 2250 g of solution A and 180 g of pretreated fluorinated graphite evenly, introduce nitrogen gas, add 270 g of 3,4-ethylenedioxythiophene, adjust the pH of the system to 2.5 with 1 mol / L hydrochloric acid, dropwise add 10.8 g of ammonium persulfate, and finish dropping in 40 min. React under ice-water bath conditions for 23 h, and after centrifugation, washing, and drying, obtain modified fluorinated graphite.

[0040] Example 4: A preparation method of fluorinated graphite, comprising the following steps: Place graphite in a fluorination reactor, fill with F2, control the pressure in the fluorination reactor 2 to be 150 kPa, and carry out fluorination reaction (reaction temperature 500 °C, reaction time 5 h) to obtain fluorinated graphite; when the pressure in the fluorination reactor exceeds 200 kPa, open the pressure relief valve, the fluorination gas source enters the cooler for cooling, and then enters the gas circulation pump to circulate back to the fluorination reactor. The gas circulation pump controls the gas flow rate to be 1.0 m 3 / h; A preparation method of a lithium carbon fluoride battery positive electrode sheet, comprising the following processes: Step S1: Mix 190 g of fluorinated graphite, 20 g of conductive agent, 20 g of binder and N-methylpyrrolidone evenly to obtain a positive electrode paste with a solid content of 70%. Step S2: Coat the positive electrode paste on the current collector, dry it and then roll it to obtain the positive electrode sheet of the lithium carbon fluoride battery. The fluorinated graphite is subjected to a modification treatment, and the specific process is as follows: Step (1): Perform mixed plasma treatment on fluorinated graphite (the process conditions of plasma treatment are: the working atmosphere is C2H2 / Ar, C2H2:Ar = 1:2, the treatment time is 20 min, the treatment power is 250 W, the vacuum degree is 40 Pa, and the treatment temperature is 300 °C) to obtain pretreated fluorinated graphite; Step (2): Heat 1900 g of polyvinyl alcohol solution to 80 °C, add sodium hydroxide solution to adjust the pH to 10, add 380 g of 2,3-epoxypropyltrimethylammonium chloride, react for 6 h, cool to room temperature, and adjust the pH to neutral to obtain the modified polyvinyl alcohol solution; Step (3): Mix 1900 g of the modified polyvinyl alcohol solution and 380 g of 6-aminoquinoline evenly, react for 5 h, introduce nitrogen, add 1140 g of isocyanatoethyl methacrylate and 34.2 g of dibutyltin dilaurate, and react at 75 °C for 8 h. Cool to room temperature and add deionized water to obtain solution A with a solid content of 20%. Step (4): Mix 1900 g of solution A and 190 g of pretreated fluorinated graphite evenly, introduce nitrogen, add 380 g of 3,4-ethylenedioxythiophene, adjust the pH of the system to 3 with 1 mol / L hydrochloric acid, dropwise add 19 g of ammonium persulfate, finish dropping in 50 min, and react under an ice-water bath condition for 24 h. After centrifugation, washing, and drying, modified fluorinated graphite is obtained.

[0041] Comparative Example 1: A preparation method of fluorinated graphite, including the following process: Compared with Example 1, the gas flow rate in Comparative Example 1 is 0.3 m 3 / h, and other steps are the same as those in Example 1.

[0042] Comparative Example 2: A preparation method of fluorinated graphite, including the following process: Compared with Example 1, the gas flow rate in Comparative Example 2 is 1.5 m 3 / h, and other steps are the same as those in Example 1.

[0043] Comparative Example 3: A preparation method of a lithium carbon fluoride battery positive electrode sheet, including the following process: Compared with Example 3, Comparative Example 3 does not include step (1), and other steps are the same as those in Example 3.

[0044] Comparative Example 4: A preparation method of a lithium carbon fluoride battery positive electrode sheet, including the following process: Compared with Example 3, in Comparative Example 4, solution A is replaced with a polyvinyl alcohol solution of the same mass, and other steps are the same as those in Example 3.

[0045] Experiment: Experiment 1: Take the fluorinated graphite obtained in Examples 1-4 and Comparative Examples 1-2, and the test results are shown in Table 1.

[0046] Table 1 Performance test of fluorinated graphite in Examples 1-4 and Comparative Examples 1-2

[0047] Experiment 2: Take the positive electrode sheets of the lithium-carbon fluoride batteries obtained in Examples 1-4 and Comparative Examples 3-4, cut them into circular pieces with a diameter of 12 mm, and place them in a glove box protected by Ar (the oxygen and water content are both less than 0.1 ppm). Assemble them in the order of the negative electrode case, negative electrode sheet, separator, positive electrode sheet, gasket, shrapnel, and positive electrode case, and seal them with a battery sealer to obtain button batteries. During the assembly process, one drop of electrolyte needs to be dropped on both sides of the separator to ensure the wetting effect of the electrolyte; among them, the model of the battery case is CR2032, the negative electrode sheet is a lithium metal sheet, the separator is made of Celgard 2400 material, and an organic solution with 0.8 M LiPF6 dissolved in ethylene carbonate: diethyl carbonate (EC:DEC) at a ratio of 1:1 is used as the electrolyte. Use a LAND CT2001A battery tester (Wuhan Blue Electric) to test the charge and discharge performance of the battery, and conduct charge and discharge tests on the button batteries at different rates (0.2C, 0.5C, 1C, 2C). The voltage range is 2.0 - 3.65V, and the 0.1C discharge capacity is used as the benchmark of 100%. The test results are shown in Table 2.

[0048] Table 2 Performance Test of the Positive Electrode Sheets of Lithium-Carbon Fluoride Batteries in Examples 1-4 and Comparative Examples 3-4

[0049] According to the data in the above table, the following conclusions can be clearly obtained: 1. Compared with Example 1, the rate performance of the products obtained in Examples 2-4 increased. It can be seen that the modification treatment of graphite fluoride in the present invention effectively enhanced its electrochemical performance.

[0050] 2. Compared with Examples 2-4, the rate performance of the products obtained in Comparative Examples 3-4 decreased, indicating that the present invention uses a C2H2 / Ar mixed plasma to modify graphite fluoride, which can effectively improve its electrochemical performance and rate ability; at the same time, compared with the polyvinyl alcohol solution, the solution A prepared in the present invention has better reaction activity and can achieve a more excellent coating effect.

[0051] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "including", "comprising" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device.

[0052] It is obvious to those skilled in the art that the present invention is not limited to the details of the above-described exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, in all respects, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Thus, all changes that fall within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims involved.

Claims

1. A method for preparing graphite fluoride, characterized in that: It includes the following steps: Place graphite in a fluorination reactor (2), charge a fluorination gas source (1), control the pressure in the fluorination reactor (2) to be 100 - 150 kPa, and conduct a fluorination reaction to obtain fluorinated graphite; when the pressure in the fluorination reactor (2) exceeds 200 kPa, open the pressure relief valve (3), the fluorination gas source enters the cooler (4) for cooling, and then enters the gas circulation pump (5) to circulate and flow back to the fluorination reactor (2).

2. The preparation method of graphite fluoride according to claim 1, characterized in that: The fluorination gas source (1) is one or more of F2, ClF, ClF3, NF3.

3. The preparation method of graphite fluoride according to claim 1, characterized in that: The reaction conditions of the fluorination reactor (2) are: reaction temperature 300 - 500 °C, reaction time 5 - 30 h.

4. The preparation method of graphite fluoride according to claim 1, wherein: The gas circulation pump (5) controls the gas flow rate to be 0.5 - 1.0 m 3 / h.

5. A kind of fluorinated graphite prepared by the preparation method according to any one of claims 1 - 4.

6. A preparation method of a positive electrode sheet of a lithium carbon fluoride battery, characterized in that: It includes the following steps: Step S1: Mix the fluorinated graphite, conductive agent, binder and solvent described in claim 5 evenly to obtain a positive electrode slurry; Step S2: Coat the positive electrode slurry on a current collector, dry it and then roll it to obtain a positive electrode plate of a lithium carbon fluoride battery.

7. The preparation method of a lithium carbon monofluoride battery positive electrode sheet according to claim 6, characterized in that: The mass ratio of the fluorinated graphite, conductive agent and binder is (80 - 95):(2 - 10):(3 - 10).

8. The preparation method of a lithium-carbon fluoride battery positive electrode sheet according to claim 7, characterized in that: The fluorinated graphite is subjected to a modification treatment, and the specific process is as follows: Step (1): Perform mixed plasma treatment on the fluorinated graphite to obtain pretreated fluorinated graphite; Step (2): Heat the polyvinyl alcohol solution to 70 - 80 °C, add a sodium hydroxide solution to adjust the pH = 9 - 10, add 2,3 - epoxypropyltrimethylammonium chloride, react for 4 - 6 h, cool to room temperature, and adjust the pH to neutral to obtain a modified polyvinyl alcohol solution; Step (3): Mix the modified polyvinyl alcohol solution and 6 - aminoquinoline evenly, introduce nitrogen, add isocyanatoethyl methacrylate and dibutyltin dilaurate, react at 65 - 75 °C for 6 - 8 h, cool to room temperature, and add deionized water to obtain solution A; Step (4): Mix solution A and fluorinated graphite evenly, introduce nitrogen, add 3,4 - ethylenedioxythiophene, use hydrochloric acid to adjust the system pH = 2 - 3, dropwise add ammonium persulfate, finish dropping in 30 - 50 min, react under ice - water bath conditions for 22 - 24 h, and after centrifugation, washing and drying, obtain modified fluorinated graphite.

9. The preparation method of a positive electrode sheet of a lithium carbon fluoride battery according to claim 8, characterized in that: In the said step (1), the process conditions of the plasma treatment are: the working atmosphere is C2H2 / Ar, C2H2:Ar = 1:(1 - 2), the treatment time is 10 - 20 min, the treatment power is 200 - 250 W, the vacuum degree is 15 - 40 Pa, and the treatment temperature is 25 - 300 °C.

10. A lithium carbon fluoride battery, characterized in that: The lithium carbon fluoride battery contains a positive electrode plate of a lithium carbon fluoride battery as described in claim 6.

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