A fast-charging graphite composite material and a preparation method thereof

Abstract

The embodiment of the present application discloses a preparation method of fast-charging graphite composite material, and the preparation process is as follows: petroleum coke or needle coke raw material, a binder and a metal pore-forming agent are uniformly mixed and briquetted, then graphitization is carried out to make the metal pore-forming agent volatilize on the matrix of the raw material to leave trace holes, and a graphite composite material is obtained; meanwhile, a composite containing a metal catalyst is prepared and deposited on the surface of the graphite composite material through a gas atomization method, then gas phase deposition is carried out through a gas phase deposition method to obtain a carbon nanotube doped amorphous carbon coated graphite composite material. The composite material has the advantages of electronic conductivity and ionic conductivity, and the rate performance of the material is improved.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery material preparation, specifically a fast-charging graphite composite material and its preparation method. Background Technology

[0002] Graphite anode materials are characterized by high energy density, good cycle performance, mature preparation technology, and low manufacturing cost, making them the mainstream commercial anode material for lithium-ion batteries. However, as the market demands increasingly higher fast charging capabilities, requiring improved fast charging performance at room temperature and low temperatures, graphite anode materials must undergo special design and processing to meet these requirements. Common methods for further improving fast charging performance include particle design and surface modification. A common approach is to reduce aggregate particle size, achieve secondary granulation through kneading, and finally graphitize to obtain a graphite anode material with a secondary particle structure. The drawback of this structure is that it is difficult to balance capacity and fast charging performance. If easily graphitized raw materials are chosen, capacity can be guaranteed, but fast charging performance is poor; if difficult-to-graphitize raw materials are chosen, fast charging performance is good, but capacity is low. After graphitization, the highly ordered particle surface also negatively impacts fast charging performance, and the high density of the core structure, while beneficial for cycle life, is detrimental to rate capability. ② Coating the material surface with soft carbon, hard carbon, and their conductive agents and fast ion conductors can improve the diffusion rate of lithium ions during charging and discharging. However, this method suffers from poor coating uniformity and density, and the core and shell are prone to delamination during long-term cycling, leading to severe cycle deterioration and reduced cycle performance. To address these issues, it is necessary to simultaneously coat both the graphite core and shell to reduce the material's impedance, improve its liquid retention capacity, enhance its kinetic properties, and improve its structural stability. Currently, there is very little research and improvement in this area on the market. Summary of the Invention

[0003] The purpose of this application is to provide a fast-charging graphite composite material and its preparation method, aiming to solve the problem that the fast-charging performance of graphite cannot be improved quickly in the prior art.

[0004] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows:

[0005] In a first aspect, this application provides a method for preparing fast-charging graphite composite material, comprising the following steps:

[0006] Petroleum coke or needle coke raw materials, binder and metal pore-forming agent are weighed and mixed, and hot-pressed to obtain block precursor material, which is then graphitized to obtain porous graphite precursor material.

[0007] A composite containing a metal catalyst is provided, wherein the porous graphite precursor material is used as a matrix, and a metal catalyst is deposited on the surface of the porous graphite precursor material by gas atomization to obtain a metal catalyst-doped graphite composite material.

[0008] An inert atmosphere is provided to carbonize the metal catalyst-doped graphite composite material in a carbon source gas to obtain a carbon nanotube-doped amorphous carbon-coated graphite composite material.

[0009] Secondly, this application provides a fast-charging graphite composite material, which is prepared by a fast-charging graphite composite material preparation method.

[0010] The method for preparing fast-charging graphite composite materials provided in the first aspect of this application involves adding a metal pore-forming agent to petroleum coke / needle coke raw materials. During graphitization, the metal pore-forming agent vaporizes, leaving nano- and micro-sized pores, thereby improving the liquid retention performance and rate performance of the graphite precursor material. Simultaneously, the metal pore-forming agent itself has a catalytic effect, accelerating the graphitization reaction process and improving efficiency. Then, a gas atomization method is used to deposit a metal catalyst in the pores of the porous graphite precursor material, which has advantages such as deep deposition depth, high density, controllable process, and high efficiency. Furthermore, the deposition thickness and type can be flexibly adjusted according to the type of deposited material. Further, the metal catalyst-doped graphite composite material is carbonized, and carbon nanotubes are grown on this substrate. The binder on the surface of the composite material is also carbonized to form amorphous carbon, reducing the material's impedance and improving its kinetic and liquid retention performance. This preparation method is simple, convenient, and easy to operate, making it suitable for large-scale preparation.

[0011] The fast-charging graphite composite material provided in the second aspect of this application is prepared by a fast-charging graphite composite material preparation method. The resulting fast-charging graphite composite material has excellent dynamic properties and liquid retention properties, which is beneficial for its wide application. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] in:

[0014] Figure 1 The image shows a SEM image of the carbon nanotube-doped amorphous carbon-coated graphite composite material prepared in Example 1. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] The first aspect of this application provides a method for preparing fast-charging graphite composite material, comprising the following steps:

[0017] S01. Weigh petroleum coke or needle coke raw materials, binder and metal pore-forming agent, mix them, and hot press them to obtain block precursor materials, and then graphitize them to obtain porous graphite precursor materials.

[0018] S02. A composite containing a metal catalyst is provided, wherein the porous graphite precursor material is used as a matrix, and a metal catalyst is deposited on the surface of the porous graphite precursor material by gas atomization to obtain a metal catalyst-doped graphite composite material.

[0019] S03. Provide an inert atmosphere and carbonize the metal catalyst-doped graphite composite material in a carbon source gas to obtain a carbon nanotube-doped amorphous carbon-coated graphite composite material.

[0020] In the preparation method of fast-charging graphite composite material provided in the first aspect of this application, a metal pore-forming agent is added to the petroleum coke / needle coke raw material. During the graphitization process, the metal pore-forming agent vaporizes and leaves nano- or micro-sized pores, improving the liquid retention performance and rate performance of the graphite precursor material. At the same time, the metal pore-forming agent itself has a catalytic effect, accelerating the graphitization reaction process and improving efficiency. Then, a gas atomization method is used to deposit a metal catalyst in the pores of the porous graphite precursor material, which has the advantages of deep deposition depth, high density, controllable process, and high efficiency. At the same time, the deposition thickness and type can be flexibly adjusted according to the type of deposited material. Furthermore, the metal catalyst-doped graphite composite material is carbonized, and carbon nanotubes are grown on this as a matrix. The binder on the surface of the composite material is carbonized to form amorphous carbon, reducing the impedance of the material and improving the kinetic performance and liquid retention performance. This preparation method is simple, convenient, and easy to operate, which is conducive to large-scale preparation.

[0021] In step S01, petroleum coke or needle coke raw materials, binder and metal pore-forming agent are weighed, mixed and treated, and hot-pressed to obtain block precursor material, and then graphitized to obtain porous graphite precursor material.

[0022] In some embodiments, the mass ratio of the petroleum coke or needle coke raw material, the binder, and the metal pore-forming agent is 100:5 to 15:1 to 5.

[0023] Petroleum coke or needle coke will form graphite materials after carbonization. Petroleum coke / needle coke itself has a residual carbon content of 60-70%. After graphitization, it can form layered artificial graphite, which can improve energy density. If carbon sources such as resin, starch, and asphalt are used, there are defects such as low residual carbon content of 20-30%, low initial efficiency, and low specific capacity, which reduce energy density.

[0024] In some embodiments, the binder is at least one selected from petroleum asphalt, coal tar pitch, phenolic resin, furfural resin, and epoxy resin. The purpose of adding the binder is to bond the petroleum coke or needle coke together for easy molding under pressure. If too much binder is added, the graphitization of the binder will leave excessive pores, reducing the specific capacity of the porous graphite precursor material. If too little binder is added, it will result in failure to bond, and the resulting blocky precursor material will be easily broken.

[0025] In some embodiments, the metal pore-forming agent is at least one selected from iron oxide, nickel oxide, cobalt oxide, titanium oxide, cerium oxide, and tungsten oxide. Adding the metal pore-forming agent serves two purposes: firstly, it volatilizes at 2800°C to form a porous structure; secondly, the metal pore-forming agent has a catalytic effect, shortening the graphitization time and accelerating the reaction process. However, excessive addition of the metal pore-forming agent can affect the structural stability of the graphite precursor and reduce cycle performance. Conversely, insufficient addition of the metal pore-forming agent will not significantly improve the reaction process, and the insufficient number of pores will affect the deposition amount of the metal catalyst complex in the next step.

[0026] Furthermore, hot pressing is performed to obtain a block precursor material. In some embodiments, the pressure of the hot pressing is 5 to 10T and the temperature is 25 to 100°C.

[0027] Further, graphitization is performed to obtain a porous graphite precursor material. In some embodiments, the graphitization temperature is 2800–2900°C.

[0028] In step S02, a composite containing a metal catalyst is provided. Using the porous graphite precursor material as a matrix, a metal catalyst is deposited on the surface of the porous graphite precursor material by gas atomization to obtain a metal catalyst-doped graphite composite material.

[0029] In some embodiments, the mass ratio of the porous graphite precursor material to the composite containing the metal catalyst is 100:1 to 10. The composite containing the metal catalyst itself has no capacity. If the mass of the composite containing the metal catalyst is too large, it will affect the energy density of the composite material; if the mass of the composite containing the metal catalyst is too small, too few carbon nanotubes will be generated in subsequent steps, resulting in insufficient improvement in electronic impedance.

[0030] In some embodiments, the preparation method of the composite containing the metal catalyst includes: mixing 1-10 parts of catalyst, 0.5-2 parts of lithium nitride and 10 parts of adhesive evenly, and pressing them into a sheet-like composite with a thickness of 0.5-5 mm by a hot press, thereby obtaining the composite containing the metal catalyst.

[0031] In some embodiments, the metal catalyst is at least one of ferric chloride, nickel chloride, and cobalt chloride.

[0032] In some embodiments, the adhesive is at least one of polypropylene, polyvinylidene fluoride, and sodium carboxymethyl cellulose.

[0033] Furthermore, a metal catalyst is deposited on the surface of the porous graphite precursor material using a gas atomization method to obtain a metal catalyst-doped graphite composite material.

[0034] In some embodiments, in the step of depositing a metal catalyst on the surface of the porous graphite precursor material using a gas atomization method, the atomizing gas pressure of the gas atomization method is 2.0 to 5 MPa, the atomization temperature is 900 to 1200°C, and the deposition time is 10 to 60 minutes.

[0035] In step S03, an inert atmosphere is provided to carbonize the metal catalyst-doped graphite composite material in a carbon source gas to obtain a carbon nanotube-doped amorphous carbon-coated graphite composite material.

[0036] In some embodiments, in the step of carbonizing the metal catalyst-doped graphite composite material in a carbon source gas, the flow rate of the carbon source gas is 10-100 ml / min; the carbonization temperature is 700-1100°C, and the time is 1-6 hours.

[0037] In some embodiments, the carbon source gas is at least one of methane, ethane, ethylene, acetylene, and natural gas.

[0038] In some specific embodiments, the preparation method of fast-charging graphite composite material includes the following steps:

[0039] Petroleum coke or needle coke raw materials are weighed according to a mass ratio of 100:5-15:1-5, and the binder and its metal pore-forming agent are mixed evenly. The mixture is then hot-pressed through a press at a pressure of 5-10T and a temperature of 25-100℃ to obtain a block precursor material. After that, it is graphitized at a temperature of 2800℃ to obtain a porous graphite precursor material.

[0040] Using a gas atomization method, a porous graphite precursor material is transferred to a high-pressure reactor. The composite containing a metal catalyst is melted at an atomization gas pressure of 2.0–5 MPa and an atomization temperature of 900–1200 °C. The composite is then deposited on the porous graphite precursor material for 10–60 min under a nitrogen or argon gas flow to obtain a metal catalyst-doped graphite composite material.

[0041] The metal catalyst-doped graphite composite material was then transferred to a tube furnace. First, an inert gas was introduced to purge the air from the tube, followed by the introduction of a carbon source gas (10-100 ml / min). The material was then carbonized at 700-1100 °C for 1-6 hours. After that, the temperature was lowered to room temperature under an argon atmosphere to obtain a carbon nanotube-doped amorphous carbon-coated graphite composite material.

[0042] The second aspect of this application provides a fast-charging graphite composite material, which is prepared by a method for preparing fast-charging graphite composite materials.

[0043] The fast-charging graphite composite material provided in the second aspect of this application is prepared by a fast-charging graphite composite material preparation method. The resulting fast-charging graphite composite material has excellent dynamic properties and liquid retention properties, which is beneficial for its wide application.

[0044] The following provides specific examples for illustration.

[0045] Example 1

[0046] Preparation of ferric chloride complex:

[0047] Mix 5g of ferric chloride, 1g of lithium nitride and 10g of polypropylene evenly, and press them into a sheet-like composite with a thickness of 2mm using a hot press to obtain the ferric chloride composite.

[0048] Step S1:

[0049] Weigh 100g of petroleum coke, 10g of petroleum pitch and 3g of iron oxide and mix them evenly. Then, use a press to hot press at a pressure of 8T and a temperature of 60℃ to obtain a block precursor material. Then, graphitize it at a temperature of 2800℃ to obtain a porous graphite precursor material.

[0050] Step S2:

[0051] Using a gas atomization method, a porous graphite precursor material was transferred to a high-pressure reactor. The ferric chloride composite was melted at an atomization gas pressure of 3 MPa and an atomization temperature of 1000 °C. The porous graphite precursor material was then deposited for 30 min under a nitrogen gas flow to obtain ferric chloride doped graphite composite material A.

[0052] Step S3:

[0053] The ferric chloride-doped graphite composite material A was then transferred to a tube furnace. First, an inert gas was introduced to purge the air from the tube, followed by the introduction of methane gas. The material was then carbonized at 900℃ for 3 hours, and then cooled to room temperature under an argon atmosphere to obtain a carbon nanotube-doped amorphous carbon-coated graphite composite material.

[0054] Example 2

[0055] Preparation of cobalt chloride complex:

[0056] 1g of cobalt chloride, 0.5g of lithium nitride and 10g of sodium carboxymethyl cellulose are mixed evenly and pressed into a sheet-like composite with a thickness of 0.5mm by a hot press to obtain the cobalt chloride composite.

[0057] Step S1:

[0058] Weigh 100g of needle coke raw material, 5g of coal tar pitch and 1g of nickel oxide and mix them evenly. Then, use a press to hot press at a pressure of 5T and a temperature of 100℃ to obtain a block precursor material. Then, graphitize it at a temperature of 2800℃ to obtain a porous graphite precursor material.

[0059] Step S2:

[0060] Using a gas atomization method, a porous graphite precursor material was transferred to a high-pressure reactor. The cobalt chloride composite was melted at an atomization gas pressure of 2.0 MPa and an atomization temperature of 900 °C. The cobalt chloride-doped graphite composite material A was then deposited on the porous graphite precursor material for 10 min under an argon gas flow.

[0061] Step S3:

[0062] The cobalt chloride-doped graphite composite material A was transferred to a tube furnace. First, argon inert gas was introduced to purge the air from the tube, and then acetylene gas was introduced. The mixture was then carbonized at 700℃ for 6 hours. After that, the temperature was lowered to room temperature in an argon atmosphere to obtain a carbon nanotube-doped amorphous carbon-coated graphite composite material.

[0063] Example 3:

[0064] Preparation of nickel chloride complex:

[0065] Mix 10g of nickel chloride, 2g of lithium nitride and 10g of polyvinylidene fluoride evenly, and press them into a sheet composite with a thickness of 5mm using a hot press to obtain the nickel chloride composite.

[0066] Step S1:

[0067] Weigh 100g of petroleum coke, 15g of phenolic resin and 5g of cerium oxide and mix them evenly. Then, use a press to hot press at a pressure of 10T and a temperature of 25℃ to obtain a block precursor material. Then, graphitize it at a temperature of 2800℃ to obtain a porous graphite precursor material.

[0068] Step S2:

[0069] Using a gas atomization method, a porous graphite precursor material was transferred to a high-pressure reactor. The nickel chloride composite was melted at an atomization gas pressure of 5 MPa and an atomization temperature of 1200 °C. The porous graphite precursor material was then deposited under a nitrogen gas flow for 60 min to obtain nickel chloride doped graphite composite material A.

[0070] Step S3:

[0071] Nickel chloride-doped graphite composite material A was transferred to a tube furnace. First, argon inert gas was introduced to purge the air inside the tube, and then natural gas was introduced. The mixture was carbonized at 1100℃ for 1 hour, and then cooled to room temperature in an argon atmosphere to obtain a carbon nanotube-doped amorphous carbon-coated graphite composite material.

[0072] Comparative example:

[0073] 100g of petroleum coke and 15g of phenolic resin were weighed and mixed evenly, and then graphitized at 2800℃ to obtain a precursor composite material. Then, 100g of the precursor composite material and 5g of nickel chloride were weighed and mixed evenly, and then transferred to a tube furnace. First, argon inert gas was introduced to remove the air in the tube, and then natural gas was introduced. The mixture was carbonized at 1100℃ for 1 hour, and then cooled to room temperature in an argon atmosphere to obtain a carbon nanotube-doped amorphous carbon-coated graphite composite material.

[0074] Experimental Example

[0075] (1) SEM testing

[0076] The graphite composite anode material prepared in Example 1 was subjected to SEM testing, and the results are as follows: Figure 1 As shown. By Figure 1 It can be seen that the particle size is between 10-15μm, the particle size distribution is reasonable, and there is a slight granulation structure.

[0077] (2) Physicochemical performance testing

[0078] The conductivity, tap density, specific surface area, particle size, and degree of graphitization of the carbon nanotube-doped amorphous carbon-coated graphite composite materials in Examples 1-3 and the comparative examples were tested according to the test methods in standard GB / T-24533-2019 "Graphite Anode Materials for Lithium-ion Batteries". The test results are shown in Table 1.

[0079] Table 1

[0080] Negative electrode active materials Example 1 Example 2 Example 3 Comparative Example Electrical conductivity (cm / S) <![CDATA[9.5*10 -9 ]]> <![CDATA[9.0*10 -9 ]]> <![CDATA[8.2*10 -9 ]]> <![CDATA[2.8*10 -10 ]]> <![CDATA[Tap density (g / cm 3 )]]> 1.14 1.15 1.09 0.91 <![CDATA[Specific surface area (m 2 / g)]]> 2.4 2.1 1.8 1.2 Particle size (μm) 12.9 12.6 13.1 13.6 Graphitization degree 95.2％ 95.1％ 95.4％ 92.9％

[0081] As can be seen from Table 1, the electrical conductivity of the carbon nanotube-doped amorphous carbon-coated graphite composite materials prepared in Examples 1-3 is significantly higher than that of the comparative examples. This may be because the surface of the materials in the examples is coated with carbon nanotubes with high electronic conductivity, which reduces impedance and increases specific surface area. At the same time, the catalyst increases the degree of graphitization.

[0082] (3) Button cell battery test

[0083] The graphite composite anode materials prepared in Examples 1-3 and the carbon nanotube-doped amorphous carbon-coated graphite composite materials of the comparative examples were assembled into coin cells according to the following methods:

[0084] The carbon nanotube-doped amorphous carbon-coated graphite composite materials prepared in Examples 1-3 and the comparative examples were used as negative electrodes and assembled into coin cells with lithium sheets, electrolytes, and separators in a glove box with argon and water contents both below 0.1 ppm. The separator was Celegard 2400; the electrolyte was a LiPF6 solution with a LiPF6 concentration of 1.1 mol / L, and the solvent was a mixed solution obtained by mixing ethylene carbonate (EC) and diethyl carbonate (DMC) in a 1:1 weight ratio.

[0085] The prepared coin cells were labeled A-1, B-1, C-1, and D-1, respectively. The performance of the coin cells was then tested using a blue electric tester. The test conditions were: 0.1C charge-discharge rate, voltage range of 0.05-2V, and 3 cycles were performed before stopping. At the same time, the rate performance of the coin cells (2C / 0.1C) was tested. The test results are shown in Table 2.

[0086] Table 2

[0087] Example 1 Example 2 Example 3 Comparative Example Initial discharge capacity (mAh / g) 357.9 356.6 356.3 352.9 First-time efficiency (%) 91.9 91.5 91.1 92.3 Multiplier (2C / 0.1C) 92.1％ 91.6％ 91.8％ 89.3％

[0088] As shown in Table 2, the coin cells prepared using the carbon nanotube-doped amorphous carbon-coated graphite composite materials of Examples 1-3 exhibit significantly higher discharge capacity and efficiency than the comparative examples. The experimental results demonstrate that the graphite composite anode material of this invention enables the battery to possess excellent discharge capacity and efficiency. This is because the catalyst in the graphite promotes carbon rearrangement, increasing the specific capacity of the material, and the carbon nanotubes reduce impedance, thereby improving rate performance.

[0089] (4) Performance testing of pouch batteries

[0090] Using carbon nanotube-doped amorphous carbon-coated graphite composite materials from Examples 1-3 and the comparative example as negative electrode active materials, and ternary materials (LiNi) as positive electrode active materials...1 / 3 Co 1 / 3 Mn 1 / 3 O2), electrolyte, and separator are assembled into a 5Ah pouch battery.

[0091] The separator was Celegard 2400, and the electrolyte was a LiPF6 solution (the solvent was a 1:1 volume ratio of EC and DEC, and the concentration of LiPF6 was 1.3 mol / L). The fabricated pouch cells were labeled A-2, B-2, C-2, and D-2, respectively.

[0092] In Examples 1-3 and the Comparative Examples, 5Ah pouch cells and their corresponding negative electrode sheets were prepared. The liquid absorption and retention capacity of the negative electrode sheets and the cycle performance of the cells were tested. The results are shown in Tables 3-4. The test methods are as follows:

[0093] 1) Liquid absorption capacity:

[0094] Using a 1 mL burette, a volume of electrolyte (V mL) was drawn and a drop was added to the electrode surface. Timing was maintained until the electrolyte was completely absorbed, and the time (t) was recorded. The absorption rate of the electrode (V / t) was then calculated. The test results are shown in Table 3.

[0095] 2) Liquid retention rate test:

[0096] The theoretical liquid absorption capacity m1 of the electrode was calculated based on the electrode parameters, and the weight m2 of the electrode was measured. The electrode was then immersed in the electrolyte for 24 hours, and its weight m3 was measured. The liquid absorption capacity m3-m2 was calculated, and the liquid retention rate was calculated using the following formula: Liquid retention rate = (m3-m2)*100% / m1. The test results are shown in Table 3.

[0097] 1) Cyclic performance: The cycle performance of the battery was tested at a charge / discharge rate of 1C / 1C, a voltage range of 2.8V-4.2V, and a temperature of 25±3℃.

[0098] 2) Rate performance: The battery was charged to 100% SOC using a 2C rate and constant current + constant voltage mode. The constant current ratio was then calculated as constant current capacity / (constant current capacity + constant voltage capacity). The test results are shown in Table 4.

[0099] Table 3

[0100] Negative electrode sheet Aspiration rate (mL / min) Electrolyte retention rate (24h electrolyte volume / 0h electrolyte volume) Example 1 5.7 92.3％ Example 2 5.3 91.2％ Example 3 5.9 90.9％ Comparative Example 3.2 85.8％

[0101] As can be seen from Table 3, the liquid absorption and retention capacity of the carbon nanotube-doped amorphous carbon-coated graphite composite materials obtained in Examples 1-3 is significantly higher than that of the comparative examples. That is, the carbon nanotube-doped amorphous carbon-coated graphite composite materials of the present invention have a high specific surface area and a porous structure, which enhances the liquid absorption capacity of the material.

[0102] Table 4

[0103] Negative electrode material used in batteries Capacity retention rate (%) after 500 cycles Fast charging performance (constant current ratio) Example 1 96.62 93.6％ Example 2 96.18 92.5％ Example 3 95.09 92.1％ Comparative Example 86.15 87.6％

[0104] Table 4 compares the cycle performance of the pouch cells prepared from the obtained negative electrode materials. As can be seen from the table, the cycle performance of the cells in the examples is significantly better than that of the comparative examples. This is because the powder in the examples has low conductivity, which reduces impedance and improves rate performance; at the same time, the materials in the examples have strong liquid retention and absorption capabilities, which improve cycle performance.

[0105] The above description discloses only preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for preparing a fast-charging graphite composite material, characterized in that, Includes the following steps: Petroleum coke or needle coke raw materials, binder and metal pore-forming agent are weighed and mixed, and hot-pressed to obtain block precursor material, which is then graphitized to obtain porous graphite precursor material. A composite containing a metal catalyst is provided, wherein the porous graphite precursor material is used as a matrix, and a metal catalyst is deposited on the surface of the porous graphite precursor material by gas atomization to obtain a metal catalyst-doped graphite composite material. An inert atmosphere is provided to carbonize the metal catalyst-doped graphite composite material in a carbon source gas to obtain a carbon nanotube-doped amorphous carbon-coated graphite composite material. The residual carbon content of the petroleum coke or needle coke raw material is 60-70%, and the mass ratio of the petroleum coke or needle coke raw material, the binder and the metal pore-forming agent is 100:5~15:1~5; the metal pore-forming agent is at least one of iron oxide, nickel oxide, cobalt oxide, titanium oxide, cerium oxide and tungsten oxide; the metal catalyst is at least one of iron chloride, nickel chloride and cobalt chloride.

2. The method for preparing the fast-charging graphite composite material according to claim 1, characterized in that, The mass ratio of the porous graphite precursor material to the composite containing the metal catalyst is 100:1~10.

3. The method for preparing the fast-charging graphite composite material according to claim 1, characterized in that, The adhesive is at least one of petroleum asphalt, coal tar pitch, phenolic resin, furfural resin, and epoxy resin.

4. The method for preparing the fast-charging graphite composite material according to claim 1, characterized in that, The hot pressing process is carried out at a pressure of 5~10 T and a temperature of 25~100℃; and / or, The graphitization treatment temperature is 2800~2900℃.

5. The method for preparing the fast-charging graphite composite material according to claim 1, characterized in that, In the step of depositing a metal catalyst on the surface of the porous graphite precursor material using a gas atomization method, the atomizing gas pressure is 2.0–5 MPa, the atomization temperature is 900–1200 °C, and the deposition time is 10–60 minutes.

6. The method for preparing the fast-charging graphite composite material according to claim 1, characterized in that, The preparation method of the composite containing the metal catalyst includes: mixing 1-10 parts of catalyst, 0.5-2 parts of lithium nitride and 10 parts of adhesive evenly, and pressing them into a sheet-like composite with a thickness of 0.5-5 mm by a hot press, thereby obtaining the composite containing the metal catalyst.

7. The method for preparing the fast-charging graphite composite material according to claim 6, characterized in that, The adhesive is at least one of polypropylene, polyvinylidene fluoride, and sodium carboxymethyl cellulose.

8. The method for preparing the fast-charging graphite composite material according to claim 1, characterized in that, In the step of carbonizing the metal catalyst-doped graphite composite material in a carbon source gas, the flow rate of the carbon source gas is 10~100 ml / min; the carbonization temperature is 700~1100℃, and the time is 1~6 hours.

9. The method for preparing the fast-charging graphite composite material according to claim 1, characterized in that, The carbon source gas is at least one of methane, ethane, ethylene, acetylene, and natural gas.

10. A fast-charging graphite composite material, characterized in that, The fast-charging graphite composite material is prepared by the preparation method of the fast-charging graphite composite material according to any one of claims 1 to 9.

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