A fast-charging graphite composite material and its preparation method

Abstract

The present invention relates to a method for preparing a fast-charging graphite composite material. A method for preparing a fast-charging graphite composite material includes: (1) dispersing a rare earth compound, a dispersant, and a metal coupling agent into an organic solvent, adding graphite, dispersing evenly, then adding an alkaline solution for co-deposition reaction, filtering, drying, and carbonizing to obtain a graphite precursor material; (2) using the graphite precursor material as a substrate and a fast ion conductor / rare earth compound / conductive agent composite as a target, and coating the target on the substrate by atomic vapor deposition. The method for preparing a fast-charging graphite composite material according to the present invention utilizes doping with rare earth metals to expand the interlayer spacing of graphite, improve the intercalation / deintercalation rate of lithium ions. At the same time, the co-deposition method can achieve uniform metal doping on the surface of graphite, and the atomic vapor deposition method is used to coat a fast ion conductor with high lithium ion conductivity on its outer layer to improve the fast-charging performance and cycling performance of the material.

Description

Technical Field

[0001] The present invention belongs to the field of lithium ion battery material preparation, and in particular relates to a fast-charging graphite composite material and a preparation method thereof. Background Art

[0002] As the market's requirements for fast-charging performance of lithium-ion batteries increase, the negative electrode materials used in lithium-ion batteries are required to have fast-charging performance while also taking into account the energy density and high-temperature performance of the materials. At present, the measures to improve the fast-charging performance of materials are mainly achieved through the following measures: 1) reducing the aggregate / finished product particle size of the material, but this will affect the energy density; 2) coating the surface of the material with amorphous carbon to increase the diffusion rate of the material; 3) doping the material with metals, oxides and fast ion conductors with high electronic conductivity to increase the exchange rate of lithium ions during charging and discharging, thereby improving the rate performance. However, the materials currently on the market mainly use methods (1) and (2), which have defects such as slow lithium ion diffusion rate and poor electronic conductivity, and the rate improvement of the battery is limited. Therefore, it is necessary to dope the core and shell of the material with metals with high electronic conductivity.

[0003] In view of this, the present invention proposes a new fast-filling graphite composite material and a preparation method thereof, which uses metal oxides and fast ion conductors to improve the overall rate performance of the material. Summary of the invention

[0004] The object of the present invention is to provide a method for preparing a fast-charging graphite composite material, which improves the fast-charging performance of the material by doping a rare earth compound in the inner core and coating the fast ion conductor / rare earth compound in the outer shell.

[0005] In order to achieve the above purpose, the technical solution adopted is:

[0006] A method for preparing a fast-filling graphite composite material comprises the following steps:

[0007] (1) After the rare earth compound, dispersant and metal coupling agent are uniformly dispersed in an organic solvent, graphite is added and uniformly dispersed, and then an alkaline solution is added to perform a co-precipitation reaction, and then filtered, dried and carbonized to obtain a graphite precursor material;

[0008] (2) Using the graphite precursor material as a substrate and the fast ion conductor / rare earth compound / conductive agent composite as a target material, the target material is coated on the substrate by atomic vapor deposition to obtain the fast-filling graphite composite material.

[0009] Furthermore, in the step (1), the mass ratio of the rare earth compound, the dispersant, the metal coupling agent, the graphite and the solute in the alkaline solution is 1-10:0.5-2:0.5-2:100:5-15;

[0010] The ratio of the total mass of the rare earth compound, dispersant and metal coupling agent to the mass of the organic solvent is 1-10:100.

[0011] Furthermore, the rare earth compound is one of Ce(NO3)3, La(NO3)3, Nd(NO3)3, Tb(NO3)3, Sm(NO3)3;

[0012] The dispersant is one of polyethylene glycol, polyvinylpyrrolidone, polyvinyl alcohol, ammonium polyacrylate, ammonium citrate, tetramethylammonium hydroxide;

[0013] The organic solvent is one of methanol, ethanol, isopropanol, butanol, isobutanol, ethylene glycol, propylene glycol, glycerol, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol butyl ether.

[0014] The metal coupling agent is one of titanate coupling agent, zirconate coupling agent, aluminate coupling agent, aluminum-zirconium bimetallic coupling agent;

[0015] The alkaline solution is one of sodium carbonate, sodium bicarbonate, ammonium carbonate, ammonium bicarbonate solution;

[0016] The fast ion conductor is one of lithium aluminum titanium phosphate, lithium lanthanum titanate, lithium lanthanum tantalate, lithium germanium aluminum phosphate, lithium lanthanum zirconium oxide, lanthanum zirconium aluminum lithium oxide;

[0017] The conductive agent is one of graphene, carbon nanotubes, super carbon black, vapor grown carbon fiber.

[0018] Furthermore, in the step (2), the process of coating the target on the substrate is to vaporize the target at 600-1000 °C, using high-purity nitrogen as the carrier gas, and introducing it into the reaction chamber in a pulsed manner, with deposition for 1-10 times.

[0019] Furthermore, in the step (2), the process of each deposition is as follows: after introducing the vaporized target and the carrier gas into the reaction chamber for 5-10 s, wait for 10-30 s, and then fill with an inert gas for purging for 30-60 s.

[0020] Still further, the flow rate of the high-purity nitrogen is 50-100 sccm.

[0021] Still further, the preparation method of the target is: adding the fast ion conductor, rare earth compound and conductive agent to asphalt, grinding evenly, and then pressing into tablets using a hot press to obtain the fast ion conductor / rare earth compound / conductive agent composite.

[0022] Further, the mass ratio of the fast ion conductor, rare earth compound, conductive agent in the target material to the graphite in step (1) is 10 - 30:10 - 30:5 - 20:100;

[0023] The mass ratio of the asphalt to the total mass of the fast ion conductor, rare earth compound, and conductive agent is 10 - 30:100.

[0024] Another object of the present invention is to provide a fast - charging graphite composite material, which is prepared by the above - mentioned preparation method and has a core - shell structure. The inner core is graphite doped with rare earth, and the outer shell is amorphous carbon containing a fast ion conductor. While having good fast - charging performance of graphite, it also takes into account energy density and high - temperature performance.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1. In the present invention, a rare earth compound with high electronic conductivity and a metal coupling agent are doped between graphites by a chemical method. On the one hand, the coupling agent forms a network structure of the graphite to reduce impedance. On the other hand, the rare earth compound itself has low electronic conductivity, reducing the internal resistance of the inner - core graphite composite.

[0027] 2. In the present invention, a fast ion conductor / rare earth compound / conductive agent composite is deposited on its outer layer by atomic vapor deposition. Relying on the characteristics of the high ionic conductivity of the fast ion conductor, high electronic conductivity of the conductive agent, and the doped rare earth compound, the electronic conductivity of the material is improved, and the lithium - ion diffusion rate during the charge - discharge process is increased, improving the rate performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 SEM of the graphite composite material prepared in Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0029] In order to further illustrate a fast - charging graphite composite material and its preparation method according to the present invention to achieve the expected invention purpose, the following is a detailed description of a fast - charging graphite composite material and its preparation method according to the present invention, its specific implementation manner, structure, characteristics, and effects, with reference to preferred embodiments. In the following description, different "one embodiment" or "embodiment" do not necessarily refer to the same embodiment. In addition, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0030] The following will further introduce in detail a fast - charging graphite composite material and its preparation method according to the present invention with specific embodiments:

[0031] Example 1.

[0032] The preparation process of the present invention is as follows: A rare earth compound, a dispersant, and a metal coupling agent are mixed evenly to obtain a graphite precursor material. Then, through atomic vapor deposition, a fast ion conductor / rare earth compound / conductive agent composite is used as a target and deposited on the surface of the graphite precursor material to obtain a fast-charging graphite composite material. The specific operation steps are as follows:

[0033] Add a rare earth compound, a dispersant, and a metal coupling agent to an organic solvent according to a mass ratio of 1-10:0.5-2:0.5-2. After dispersing evenly, add artificial graphite and disperse evenly. Then add an alkaline solution for co-deposition reaction. After that, filter, dry in vacuum, and carbonize at 800 °C for 3 h to obtain a graphite precursor material.

[0034] Among them, the mass ratio of the rare earth compound, graphite, and the solute (i.e., the alkaline substance) in the alkaline solution is 1-10:100:5-15.

[0035] The rare earth compound is one of Ce(NO3)3, La(NO3)3, Nd(NO3)3, Tb(NO3)3, Sm(NO3)3.

[0036] The dispersant is one of polyethylene glycol, polyvinylpyrrolidone, polyvinyl alcohol, ammonium polyacrylate, ammonium citrate, and tetramethylammonium hydroxide.

[0037] The organic solvent is one of methanol, ethanol, isopropanol, butanol, isobutanol, ethylene glycol, propylene glycol, glycerol, ethylene glycol methyl ether, ethylene glycol ethyl ether, and ethylene glycol butyl ether.

[0038] The metal coupling agent is one of titanate coupling agents, zirconate coupling agents, aluminate coupling agents, and aluminum-zirconium bimetallic coupling agents.

[0039] The alkaline solution is one of sodium carbonate, sodium bicarbonate, ammonium carbonate, and ammonium bicarbonate.

[0040] (2) Through atomic vapor deposition, using the graphite precursor material as a substrate and the fast ion conductor / rare earth compound / conductive agent composite as a target, vaporize the target at 600-1000 °C, and use high-purity nitrogen as a carrier gas with a flow rate of 50-100 Sccm.

[0041] Introduce the vaporized target and the carrier gas into the reaction chamber in a pulsed manner. The pulse time is 5-10 s. After a waiting time of 10-30 s, introduce an inert gas, argon, into the reaction chamber to purge the composite deposited on the surface of the graphite precursor material for 30-60 s. This process is regarded as one cycle. Deposit in cycles according to this step for 1-10 weeks to obtain a fast ion conductor / rare earth compound / conductive agent-coated graphite composite material, that is, the graphite composite material described above.

[0042] Among them, the preparation of the fast ion conductor / rare earth compound / conductor complex: Weigh the fast ion conductor, rare earth compound, and conductor according to a mass ratio of 10-30:10-30:5-20, add them to asphalt and grind evenly. Then, use a hot press to press tablets at a pressure of 2 Mpa and a temperature of 100 °C to obtain the fast ion conductor / rare earth compound / conductor complex.

[0043] The mass of the asphalt is 10-30% of the total mass of the fast ion conductor, rare earth compound, and conductor.

[0044] The fast ion conductor is one of lithium titanium aluminum phosphate, lithium lanthanum titanate, lithium lanthanum tantalate, lithium germanium aluminum phosphate, lithium lanthanum zirconium oxide, and lanthanum zirconium aluminum lithium oxide; the conductor is one of graphene, carbon nanotubes, super carbon black, and vapor grown carbon fiber.

[0045] Example 2.

[0046] The specific operation steps are as follows:

[0047] (1) Add 5 g of Ce(NO3)3, 1 g of polyethylene glycol, and 1 g of titanate coupling agent to 140 g of methanol organic solvent and disperse evenly. Then, add 100 g of artificial graphite and disperse evenly. Next, add 100 g of 10 wt% sodium carbonate solution for co-deposition reaction. After that, filter, dry in vacuum at 80 °C for 24 h, and carbonize at 800 °C for 3 h to obtain the graphite precursor material.

[0048] (2) By atomic vapor deposition method, using the graphite precursor material as the substrate and the fast ion conductor / rare earth compound / conductor complex as the target, vaporize the target at 800 °C, with high-purity nitrogen as the carrier gas and a flow rate of 80 Sccm.

[0049] Feed the vaporized target and the carrier gas into the reaction chamber in a pulsed manner, with a pulse time of 8 s. After a waiting time of 20 s, fill the reaction chamber with argon inert gas to purge the complex deposited on the surface of the graphite precursor material for 45 s. This process is regarded as one cycle. Deposit in cycles according to this step for 5 weeks to obtain the fast ion conductor / rare earth compound / conductor-coated graphite composite material, that is, the graphite composite material mentioned above.

[0050] Among them, the preparation of the fast ion conductor / rare earth compound / conductor complex: Weigh 20 g of lithium titanium aluminum phosphate, 20 g of Ce(NO3)3, and 10 g of carbon nanotubes, add them to the above-mentioned 10 g of asphalt and grind evenly. Then, use a hot press and press tablets at a pressure of 2 Mpa and a temperature of 100 °C to obtain the fast ion conductor / rare earth compound / conductor complex.

[0051] Example 3.

[0052] The specific operation steps are as follows:

[0053] (1) 1 g of La(NO3)3, 0.5 g of polyvinylpyrrolidone, and 0.5 g of zirconate coupling agent were added to 200 g of isobutanol and dispersed evenly. Then, 100 g of artificial graphite was added and dispersed evenly. Next, 50 g of 10 wt% ammonium carbonate alkaline solution was added for co-deposition reaction. After that, filtration was carried out, followed by vacuum drying, and carbonization at 800 °C for 3 h to obtain the graphite precursor material.

[0054] (2) By atomic vapor deposition method, using the graphite precursor material as the substrate and the fast ion conductor / rare earth compound / conductor complex as the target, the target was vaporized at 600 °C, with high-purity nitrogen as the carrier gas and a flow rate of 50 Sccm.

[0055] The vaporized target and the carrier gas were introduced into the reaction chamber in a pulsed manner, with a pulse time of 5 S. After a waiting time of 10 S, argon inert gas was introduced into the reaction chamber to purge the complex deposited on the surface of the graphite precursor material for 30 S. This process was regarded as one cycle. Deposition was carried out in cycles according to this step for 1 week to obtain the fast ion conductor / rare earth compound / conductor-coated graphite composite material, that is, the graphite composite material described above.

[0056] Among them, the preparation method of the fast ion conductor / rare earth compound / conductor complex: Weigh 10 g of lithium lanthanum titanate, 10 g of La(NO3)3, and 5 g of carbon nanotubes, add them to 2.5 g of asphalt and grind evenly. Then, use a hot press to carry out tablet pressing at a pressure of 2 Mpa and a temperature of 100 °C to obtain the fast ion conductor / rare earth compound / conductor complex, that is, the graphite composite material described above.

[0057] Example 4.

[0058] The specific operation steps are as follows:

[0059] (1) 10 g of Nd(NO3)3, 2 g of polyvinyl alcohol, and 2 g of aluminate coupling agent were added to 140 g of glycerol organic solvent and dispersed evenly. Then, 100 g of artificial graphite was added and dispersed evenly. Next, 150 g of 10 wt% ammonium bicarbonate solution was added for co-deposition reaction. After that, filtration was carried out, followed by vacuum drying at 80 °C for 24 h and carbonization at 800 °C for 3 h to obtain the graphite precursor material.

[0060] (2) By atomic vapor deposition method, using the graphite precursor material as the substrate and the fast ion conductor / rare earth compound / conductor complex as the target, the target was vaporized at 1000 °C, with high-purity nitrogen as the carrier gas and a flow rate of 100 Sccm.

[0061] The vaporized target material and carrier gas are introduced into the reaction chamber in a pulsed manner. The pulse time is 10 s. After a waiting time of 30 s, an inert gas, argon, is introduced into the reaction chamber to purge the composite deposited on the surface of the graphite precursor material for 60 s. This process is regarded as one cycle. Deposition is carried out in cycles according to this step for 10 weeks to obtain a fast ion conductor / rare earth compound / conductive agent-coated graphite composite material, namely the graphite composite material (abbreviation, graphite composite material).

[0062] Among them, the preparation method of the fast ion conductor / rare earth compound / conductive agent composite: Weigh 30 g of lithium lanthanum tantalate, 30 g of Nd(NO3)3, and 20 g of super carbon black, add them to 24 g of asphalt and grind evenly. Then, use a hot press to press tablets at a pressure of 2 Mpa and a temperature of 100 °C to obtain the fast ion conductor / rare earth compound / conductive agent composite.

[0063] Comparative Example 1:

[0064] The graphite precursor material prepared in step (1) of Example 2 is pulverized and used as the negative electrode material.

[0065] Comparative Example 2:

[0066] Take 10 g of the fast ion conductor / rare earth compound / conductive agent composite prepared in Example 2, add it to 200 ml of butanediol and disperse evenly. Then add the graphite precursor material in step (1) of Example 2, and then disperse evenly by ultrasonic treatment, followed by spray drying. Then, it is heated to 800 °C in an inert atmosphere and carbonized for 3 h, and then pulverized to obtain the graphite composite material.

[0067] Performance test:

[0068] (1) SEM test

[0069] The SEM image of the graphite composite material prepared in Example 2 is as Figure 1 shown; it can be seen from the figure that the material presents a spherical-like structure, with a reasonable size distribution, good granulation degree, and the particle size is between (10 - 15) μm, where D50 is 11 μm.

[0070] (2) Coin cell test:

[0071] The lithium-ion battery anode materials obtained in Examples 2-4 and Comparative Examples 1-2 were assembled into button cells A1, A2, A3, B1, and B2, respectively. The preparation method was as follows: a binder, a conductive agent, and a solvent were added to the anode material, stirred to make a slurry, coated on a copper foil, and obtained through drying and rolling. The binder used was LA132 binder, the conductive agent was SP, the anode materials were the anode materials prepared in Examples 2-4 and Comparative Examples 1-2 respectively, the solvent was secondary distilled water, and the ratio was: anode material: SP: LA132: secondary distilled water = 95 g: 1 g: 4 g: 220 mL, and the anode electrode was prepared. The electrolyte was LiPF6 / EC+DEC (1:1), the lithium metal sheet was the counter electrode, the separator was a polyethylene (PE), polypropylene (PP), or polyethylene-propylene (PEP) composite film, the simulation battery assembly was carried out in a glove box filled with argon, and the electrochemical performance was carried out on a Wuhan Blue Electric CT2001A battery tester. The charge and discharge voltage range was 0.005 V to 2.0 V, and the charge and discharge rate was 0.1C. The first discharge capacity, efficiency, specific surface area, and OI value were tested according to the GBT-24533-2019 "Graphite Anode Materials for Lithium-Ion Batteries" standard, and the rate performance (3C / 0.2C) and cycle performance (0.2C / 0.2C, 100 cycles) of the button cells were tested. The test results are shown in Table 1.

[0072] Table 1

[0073]

[0074] As can be seen from Table 1, the first discharge capacity and the first charge-discharge efficiency of the lithium-ion batteries using the graphite composite materials obtained in Examples 2-4 were significantly higher than those in Comparative Examples 1-2. The experimental results show that by depositing fast ion conductors on the outer surface of the material in the present invention, lithium ions are provided during the first charge-discharge process, thereby improving its first efficiency; and relying on the rare earth compounds doped with graphite, the lithium ion extraction channels are improved, and its rate performance is improved.

[0075] (3) Production and testing of soft-pack batteries

[0076] The materials prepared in Examples 2-4 and Comparative Examples 1-2 were used as the anode materials. Using ternary materials (LiNi 1 / 3 Co 1 / 3Mn 1 / 3 O2) as the cathode, LiPF6 (the solvent was EC+DEC, volume ratio 1:1, concentration 1.3 mol / L) as the electrolyte, and celegard2400 as the separator, 2Ah soft-pack batteries C1, C2, C3, D1, and D2 were prepared, that is, ternary lithium batteries were obtained.

[0077] 3.1 Rate performance test:

[0078] The rate performance of the above-mentioned soft-pack battery was tested. The charge-discharge voltage range was 2.75 - 4.2 V, the temperature was 25 ± 3.0 °C, and it was charged at 1.0C, 3.0C, 5.0C, and 10.0C and discharged at 1.0C. The results are shown in Table 2.

[0079] Table 2

[0080]

[0081]

[0082] As can be seen from Table 2, the rate charging performance of the soft-pack batteries in Examples 2 - 4 is significantly better than that of Comparative Examples 1 - 2, that is, the charging time is shorter. The reason is as follows: During the battery charging process, the migration of lithium ions is required, and the negative electrode materials in the examples have more pore structures, providing more channels for the intercalation of lithium ions, thus improving their rate performance; at the same time, the coated fast ion conductor can improve the electron transfer rate and the rate performance.

[0083] 3.2, Liquid Absorption and Retention Capacity of the Electrode Sheet

[0084] The liquid absorption rate of the negative electrode sheets obtained when preparing lithium-ion batteries in Examples 2 - 4 and Comparative Examples 1 - 2 was tested according to the following method: In the glove box, a 1 cm × 1 cm negative electrode sheet was selected, the electrolyte was sucked into a burette, and then titrated onto the electrode sheet until there was no obvious electrolyte on the surface of the electrode sheet, and the time and the added amount of the electrolyte were recorded, thus obtaining the liquid absorption rate. The test method for the liquid retention rate: Calculate the theoretical electrolyte injection amount m1 according to the electrode sheet parameters, place the electrode sheet in the theoretical electrolyte for 24 h, weigh the electrolyte absorbed by the electrode sheet m2, and finally obtain the liquid retention rate = m2 / m1 * 100%. The test results are shown in Table 3.

[0085] Table 3

[0086]

[0087]

[0088] As can be seen from Table 3, the liquid absorption capacity of the negative electrode sheets prepared in Examples 2 - 4 is significantly better than that of Comparative Example 1. The reason is that the graphite negative electrode material has a pore structure and a high specific surface area, which improves the liquid absorption and retention capacity of the material.

[0089] 3.3, High-Temperature Storage Test

[0090] The test method for high-temperature storage performance is as follows: At 55 °C for 14 days, test the high-temperature performance (charge retention and capacity recovery) of the battery; the test results are shown in Table 4.

[0091] Table 4

[0092]

[0093] As can be seen from Table 4, the cycling performance of the lithium-ion batteries prepared with the graphite composite anode materials obtained in Examples 2-4 is significantly better than that of Comparative Examples 1-2 at each stage. The experimental results show that the electrode materials prepared by the present invention have good structural stability, thereby improving their high-temperature performance.

[0094] The above are only the preferred embodiments of the embodiments of the present invention, and do not impose any formal restrictions on the embodiments of the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the embodiments of the present invention still fall within the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of a fast-charging graphite composite material, characterized in that It includes the following steps: (1) After uniformly dispersing a rare earth compound, a dispersant, and a metal coupling agent in an organic solvent, graphite is added, and after uniform dispersion, an alkaline solution is added for co-deposition reaction, followed by filtration, drying, and carbonization to obtain a graphite precursor material; (2) Using the obtained graphite precursor material as a substrate and a fast ion conductor / rare earth compound / conductor complex as a target, the target is coated on the substrate by atomic vapor deposition to obtain the fast-charging graphite composite material; Among them, the rare earth compound is one of Ce(NO3)3, La(NO3)3, Nd(NO3)3, Tb(NO3)3, Sm(NO3)3; The fast ion conductor is one of lithium aluminum titanium phosphate, lithium lanthanum titanate, lithium lanthanum tantalate, lithium germanium aluminum phosphate, lithium lanthanum zirconium oxide, and lithium lanthanum zirconium aluminum oxide.

2. The preparation method according to claim 1, wherein in the step (1), the mass ratio of the rare earth compound, the dispersant, the metal coupling agent, graphite, and the solute in the alkaline solution is 1-10:0.5-2:0.5-2:100:5-15; the ratio of the total mass of the rare earth compound, the dispersant, and the metal coupling agent to the mass of the organic solvent is 1-10:

100.

3. The preparation method according to claim 1, wherein the dispersant is one of polyethylene glycol, polyvinylpyrrolidone, polyvinyl alcohol, ammonium polyacrylate, ammonium citrate, and tetramethylammonium hydroxide; the organic solvent is one of methanol, ethanol, isopropanol, butanol, isobutanol, ethylene glycol, propylene glycol, glycerol, ethylene glycol methyl ether, ethylene glycol ethyl ether, and ethylene glycol butyl ether; the metal coupling agent is one of titanate coupling agents, zirconate coupling agents, aluminate coupling agents, and aluminum-zirconium bimetallic coupling agents; the alkaline solution is one of sodium carbonate, sodium bicarbonate, ammonium carbonate, and ammonium bicarbonate solutions; the conductor is one of graphene, carbon nanotubes, super carbon black, and vapor-grown carbon fibers.

4. The preparation method according to claim 1, wherein in the step (2), the process of coating the target on the substrate is to vaporize the target at 600-1000 °C, using high-purity nitrogen as a carrier gas, and introducing it into the reaction chamber in a pulsed manner for deposition 1-10 times.

5. The preparation method according to claim 4, wherein in the step (2), the process of each deposition is: after introducing the vaporized target and the carrier gas into the reaction chamber for 5-10S, wait for 10-30S, and then fill with an inert gas for purging for 30-60S.

6. The preparation method according to claim 4, wherein the flow rate of the high-purity nitrogen is 50-100 Sccm.

7. The preparation method according to claim 5, wherein the preparation method of the target is: adding a fast ion conductor, a rare earth compound, and a conductor to asphalt, grinding evenly, and then using a hot press to press into a sheet to obtain the fast ion conductor / rare earth compound / conductor complex.

8. The preparation method according to claim 7, wherein The mass ratio of the fast ion conductor, rare earth compound, conductive agent in the target material to the graphite in step (1) is 10 - 30:10 - 30:5 - 20:100; The mass ratio of the asphalt to the total mass of the fast ion conductor, rare earth compound, and conductive agent is 10 - 30:

100.

9. A fast-charging graphite composite material, characterized in that, The fast - charging graphite composite material is prepared by the preparation method described in any one of claims 1 - 8, and has a core - shell structure. The inner core is graphite doped with rare earth, and the outer shell is amorphous carbon containing a fast ion conductor.

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