Long cycle lithium ion battery regenerated graphite negative electrode material and preparation method thereof

Abstract

The application relates to the technical field of lithium ion batteries, in particular to a long-cycle lithium ion battery regenerated graphite negative electrode material and a preparation method thereof, which comprises the following steps: drying, crushing and shaping waste graphite powder to obtain fine powder; modifying and coating the graphite powder twice by respectively adding a binder mixture and a carbon source; performing graphitization treatment on the modified graphite powder to obtain a graphite material; removing magnetism from the graphite material, and screening, so that the long-cycle lithium ion battery graphite negative electrode material is obtained. The method can effectively repair the internal and surface structural defects of the waste graphite negative electrode material, can improve the cycle stability and capacity retention rate of the scrapped graphite negative electrode material, and prolongs the service life of the battery.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium ion batteries, in particular to a long-cycle lithium ion battery regenerated graphite negative electrode material and a preparation method thereof. BACKGROUND

[0002] As an important energy storage device, lithium ion batteries are widely used in electric vehicles, portable electronic devices, large-scale energy storage systems and other fields. The negative electrode material is one of the four key materials of lithium ion batteries, accounting for more than 10% of the cost of lithium ion batteries. The negative electrode material has an important influence on the energy density, cycle performance, charge / discharge rate and low-temperature discharge performance of lithium ion batteries. Among them, graphite as a common negative electrode material has excellent electrical conductivity and lithium storage performance.

[0003] With the rapid development of new energy vehicle industry, the demand for lithium ion batteries has been increasing in recent years. During the charging and discharging process of lithium batteries, lithium ions are inserted / extracted in graphite, and graphite expands / contracts. During the expansion / contraction process, the SEI film on the surface of the graphite is continuously broken / healed, resulting in decomposition of the electrolyte in the battery and reduction of active lithium ions. In the long-term use and cycle charging and discharging process, the graphite negative electrode material is prone to problems such as capacity attenuation and increased internal resistance, which limits the service life and performance of the battery. Therefore, there is a potential large number of waste batteries.

[0004] Currently, the recycling of lithium battery materials mainly focuses on the positive active materials such as lithium, cobalt, nickel, manganese, etc. and valuable metals such as metal current collectors aluminum and copper. Since the negative electrode graphite has a wide source and low recycling added value, the recycling technology and industry development for the negative electrode are still in the initial stage. Some recycling manufacturers can recycle waste graphite to obtain graphite material as a lithium ion battery negative electrode material. However, due to the defects of the material itself, the obtained graphite negative electrode material has poor cycle stability and low capacity retention rate in actual application compared to traditional lithium ion battery graphite negative electrode materials, which limits the service life and performance of the battery. The main reason is that the bulk phase and surface of the waste graphite are damaged to different degrees after a long time of cycling, which needs to be repaired by structural regeneration means.

[0005] Therefore, there is an urgent need for a method to solve the above problems. SUMMARY

[0006] The purpose of the present application is to overcome the defects of poor cycle stability and low capacity retention rate of lithium ion batteries prepared from existing waste graphite materials. The present application provides a long-cycle lithium ion battery regenerated graphite negative electrode material with good cycle stability and high capacity retention rate and a preparation method thereof.

[0007] In a first aspect, the application provides a preparation method of a long-cycle lithium ion battery regenerated graphite negative electrode material, which adopts the following technical scheme:

[0008] A preparation method of a long-cycle lithium ion battery regenerated graphite negative electrode material, comprising the following steps:

[0009] S1. Dry, crush and shape waste graphite powder to obtain fine powder;

[0010] S2. Mix the fine powder in step S1 with a binder, heat to 500-800 DEG C under an inert atmosphere, and keep the temperature for 2-6 hours to obtain material I;

[0011] S3. Re-disperse material I in step S2, add a carbon source and mix well to obtain material II;

[0012] S4. Carbonize material II obtained in step S3 at 700-1500 DEG C for 5-10 hours to obtain material III;

[0013] S5. Graphitize material III in step S4 to obtain a graphite material;

[0014] S6. Remove the magnetic field and sieve the graphite material obtained in step S5 to obtain a regenerated graphite negative electrode material.

[0015] In the present application, the waste graphite powder is first dried, crushed and shaped to obtain graphite powder with appropriate particle size. The above steps can remove the sharp edges and corners of the graphite powder particles, making the particles more rounded, reducing the sharp end active site and improving the high temperature performance. The binder has good viscosity and adhesion, which can effectively bond the waste graphite powder together, granulate the waste graphite powder, and the binder exhibits good fluidity within a suitable temperature range, can be adsorbed by the waste graphite powder and can penetrate into the gaps of the waste graphite powder, can also wrap the graphite powder, repair the structural damage of the waste graphite powder, and thus modify the waste graphite powder. Then the graphite powder particles are dispersed again, mixed with a carbon source, heated to 700-1500°C, and then the material II is subjected to high-temperature carbonization treatment to remove the volatile matter in the material II and convert the amorphous carbon chain molecules in the graphite coating layer into stable structures to form a hard carbon coating layer, further repairing the pores and exposed surface layer structure left by the waste graphite powder after use. Because the waste graphite powder has serious structural damage, its performance is still inferior to that of the standard graphite negative electrode material after two carbon coating repairs, so the present application further graphitizes the twice modified graphite powder. Firstly, most of the impurities in the graphite powder can be removed, the ash content is reduced, and the purpose of purification is achieved. Secondly, the disordered structure of the original coated carbon material is converted into an ordered structure by carbon rearrangement, thereby converting the coating layer into graphite and making the regenerated graphite powder into a perfect particle. The regenerated graphite negative electrode material can be obtained by removing the magnet and sieving.

[0016] The present application uses waste lithium ion battery negative graphite powder as raw material and uses regenerated graphite material as lithium ion battery graphite negative material, thereby reducing the production cost of lithium ion battery negative material and fully recycling the waste graphite powder. The lithium ion battery prepared by using the regenerated graphite material of the present application has a discharge capacity of 345mAh / g or more, a first efficiency of 93% or more, and a capacity retention rate of 80% or more after 3000 cycles at room temperature 1C, indicating that the method of the present application can effectively repair the internal and surface structural defects of the waste graphite negative material, improve the cycle stability and capacity retention rate of the waste graphite negative material, and prolong the service life of the battery.

[0017] Optionally, the waste graphite powder is dried at 100-200°C to remove the water in the waste graphite powder.

[0018] By using the above technical solution, the water contained in the waste graphite powder and adsorbed during storage can be removed by drying the waste graphite powder at 100-200°C.

[0019] Optionally, in the step S1, the particle size D50 of the fine powder is 14.00±2.0 microns, and D100 is less than 50 microns.

[0020] By adopting the above technical scheme, the irregular structure of the waste graphite negative electrode material is crushed and shaped to obtain graphite fine powder with appropriate particle size, facilitating subsequent granulation and wrapping treatment.

[0021] Optionally, in the step S2, the mass ratio of the fine powder to the binder is 100:2-8.

[0022] By adopting the above technical scheme, the introduction of an appropriate amount of binder can granulate the waste graphite powder and form a certain coating layer on the surface of the waste graphite powder.

[0023] Optionally, in the step S3, the mass ratio of the material I to the carbon source is 100:5-20.

[0024] By adopting the above technical scheme, the introduction of an appropriate amount of binder can complete the wrapping of the surface of the graphite fine powder and repair the structural damage of the graphite powder; if the amount of the binder is too small, the binder cannot completely wrap the graphite fine powder, the defects on the surface of the graphite fine powder cannot be completely covered and repaired, and the performance of the regenerated graphite material is affected; if the amount of the binder is too large, the introduction of too much amorphous carbon will cause the first efficiency of the obtained regenerated graphite material to decrease, so the performance of the lithium ion battery will be affected.

[0025] Optionally, the binder is selected from one of pitch, petroleum coke and furfural resin;

[0026] And / or, the carbon source is selected from one of phenolic resin and epoxy resin.

[0027] By adopting the above technical scheme, the binder such as pitch, petroleum coke and furfural resin has good viscosity and adhesion, which can effectively bond the waste graphite powder together to form a solid formed material with a specific shape and strength; the carbon source such as phenolic resin and epoxy resin has good thermal stability, which can melt and be coated on the surface of the graphite for the second time to form a microcrystalline structure, which helps to improve the cycle performance of the obtained regenerated graphite material.

[0028] Optionally, the carbon source is pretreated before use, and the pretreatment includes the following steps: (1) mixing the carbon source and bismaleimide resin to prepare a mixture;

[0029] (2) melting the mixture prepared in step (1) and extruding and granulating to obtain the mixture.

[0030] By adopting the technical scheme, the phenolic resin and the epoxy resin have good mechanical properties, strong adhesion to graphite, and acid and alkali resistance, but the mechanical impact resistance is poor; the bismaleimide resin has an imide ring structure, and thus has strong mechanical properties and thermal stability, good toughness, similar fluidity and moldability to the phenolic resin and the epoxy resin, and can be processed by the same general method as the phenolic resin and the epoxy resin; the toughness and impact resistance of the carbon source can be improved by mixing the carbon source with the bismaleimide resin, so that the carbon source is wrapped in the graphite, and the prepared graphite negative electrode material has better toughness and mechanical impact resistance, and is more conducive to subsequent battery processing.

[0031] Optionally, the material III obtained in step S4 is kept at 3000℃ for 6-8 hours.

[0032] By adopting the technical scheme, the graphite negative electrode material is converted from a disordered and irregular arrangement of carbon atoms to a regular hexagonal plane net structure at high temperature, i.e. from a random layer structure to an ordered graphite crystal structure, so that the graphite has high conductivity, high thermal conductivity, corrosion resistance, friction resistance and other properties. The high temperature of 3000℃ can gradually eliminate the distortion and defects in the microcrystal and convert it into graphitized carbon, and the obtained regenerated graphite negative electrode material has high graphitization degree, the coating layer is converted into graphite, the regenerated graphite powder becomes a perfect particle, and good cycle performance is obtained.

[0033] In a second aspect, the regenerated graphite negative electrode material for a long-cycle lithium ion battery provided by the application adopts the following technical scheme:

[0034] The regenerated graphite negative electrode material for a long-cycle lithium ion battery is prepared by the above preparation method.

[0035] By adopting the technical scheme, the regenerated graphite negative electrode material obtained by the above process repairs the defects of the original waste graphite negative electrode material, so that the performance is obviously improved, and the cost is lower than that of a graphite negative electrode material prepared from natural graphite.

[0036] In a third aspect, the long-cycle lithium ion battery provided by the application adopts the following technical scheme:

[0037] The long-cycle lithium ion battery adopts the regenerated graphite negative electrode material.

[0038] By adopting the technical scheme, the lithium ion battery prepared by using the regenerated graphite negative material has a discharge capacity of 347mAh / g or more, a first efficiency of 96% or more, and a capacity retention rate of 80% or more after 3000 cycles at room temperature 1C, and meets the use standard and has low cost.

[0039] In summary, the present application includes at least one of the following beneficial technical effects:

[0040] 1. The method is simple and easy to promote. The waste lithium ion battery negative graphite powder is used as the raw material, and the regenerated graphite material is used as the lithium ion battery graphite negative material, which reduces the production cost of the lithium ion battery negative material and fully recycles the waste graphite powder. The lithium ion battery prepared by the regenerated graphite material has a discharge capacity of more than 345 mAh / g, a first efficiency of more than 94%, and a capacity retention rate of more than 80% after 3000 cycles at room temperature 1C, which shows that the method can effectively repair the internal and surface structural defects of the waste graphite negative material, improve the cycle stability and capacity retention rate of the waste graphite negative material, and prolong the service life of the battery.

[0041] 2. The present application improves the toughness and impact resistance of the carbon source by mixing the carbon source with bismaleimide resin, so that the carbon source is wrapped in graphite, and the prepared graphite negative material has better toughness and mechanical impact resistance, which is beneficial to subsequent battery processing; 3. The graphite negative material converts the carbon atoms from irregular arrangement to regular hexagonal plane net structure at high temperature, i.e. from random layer structure to ordered graphite crystal structure, which can obtain the properties of high conductivity, high thermal conductivity, corrosion resistance and friction resistance of graphite. The high temperature of 3000℃ can gradually eliminate the distortion and defects in the microcrystal and convert it into graphitized carbon, and the obtained regenerated graphite negative material has high graphitization degree, changes the coating layer into graphite, and makes the regenerated graphite powder into a perfect particle, which has good cycle performance. DETAILED DESCRIPTION

[0042] The present application will be further described in detail below in combination with examples and comparative examples.

[0043] For the sake of brevity, the articles used in the following examples are all commercially available products unless otherwise specified, and the methods used are all conventional methods unless otherwise specified.

[0044] Preparation Example

[0045] Preparation Example 1

[0046] The pretreatment of the carbon source provided by the present preparation example includes the following steps:

[0047] (1) mixing phenolic resin and bismaleimide resin to prepare a mixture; the mass ratio of the phenolic resin and the bismaleimide is 6:1;

[0048] (2) melting the mixture prepared in step (1) and extruding and granulating to obtain.

[0049] Preparation Example 2

[0050] The pretreatment of the carbon source provided in the preparation example includes the following steps:

[0051] (1) mixing the epoxy resin and the bismaleimide resin to prepare a mixture; the mass ratio of the phenolic resin to the bismaleimide is 6:1;

[0052] (2) melting and extruding the mixture prepared in step (1) to obtain granules.

[0053] Embodiment

[0054] Embodiment 1

[0055] The preparation method of the regenerated graphite negative electrode material of the embodiment includes the following steps:

[0056] S1. drying the waste graphite powder at 120°C to remove the moisture in the waste graphite powder;

[0057] S2. crushing the waste graphite powder by using a high-speed crusher to obtain fine powder, the particle size D50 of the fine powder is 14.00±2.0 μm, and D100<50 μm;

[0058] S3. placing the fine powder in step S2 in a shaper, and using the friction between the materials to unify the shape of the particle surface, so that the particles have a regular morphology similar to that of potatoes.

[0059] S4. mixing the fine powder in step S3 with pitch, heating to 650°C under an argon inert atmosphere, the heating rate is 10°C / min, and the holding time is 4 hours to obtain material I;

[0060] The mass ratio of the fine powder to coal pitch is 100:5;

[0061] S5. re-dispersing the material I obtained in step S4, the particle size D10 of the dispersed material I is >6 μm, D50=14.00±2.0 μm, and D90<35 μm, then adding a carbon source and mixing to obtain material II;

[0062] The mass ratio of the material I to the carbon source is 100:10; the carbon source is the carbon source provided in the preparation example 1;

[0063] S6. carbonizing the material II obtained in step S5 at 800°C for 8 hours to obtain material III;

[0064] S7. graphitizing the material III in step S6 at 3000°C for 7 hours to obtain a graphite material;

[0065] S8. removing the magnetic field and sieving the graphite material obtained in step S7 to obtain a regenerated graphite negative electrode material.

[0066] The waste graphite powder in step S1 is collected from the market by collecting the negative electrode graphite powder of the waste lithium ion battery.

[0067] Example 2

[0068] The difference between this example and Example 1 is that in step S5, the mass ratio of material I to carbon source is 100:5, and the remaining steps and components are the same as those in Example 1.

[0069] Example 3

[0070] The difference between this example and Example 1 is that in step S5, the mass ratio of material I to carbon source is 100:15, and the remaining steps and components are the same as those in Example 1.

[0071] Example 4

[0072] The difference between this example and Example 1 is that in step S5, the mass ratio of material I to carbon source is 100:20, and the remaining steps and components are the same as those in Example 1.

[0073] Example 5

[0074] The difference between this example and Example 3 is that in step S5, the mass ratio of fine powder to coal pitch is 100:2, and the remaining steps and components are the same as those in Example 3.

[0075] Example 6

[0076] The difference between this example and Example 3 is that in step S5, the mass ratio of fine powder to coal pitch is 100:8, and the remaining steps and components are the same as those in Example 3.

[0077] Example 7

[0078] The difference between this example and Example 2 is that in step S5, the carbon source is replaced by the carbon source provided in Preparation Example 2, and the remaining steps and components are the same as those in Example 3.

[0079] Example 8

[0080] The difference between this example and Example 3 is that in step S5, the coal pitch is replaced by petroleum pitch, and the remaining steps and components are the same as those in Example 3.

[0081] Example 9

[0082] The difference between this example and Example 2 is that in step S5, the coal pitch is replaced by furfural resin, and the remaining steps and components are the same as those in Example 3.

[0083] Comparative Example

[0084] Comparative Example 1

[0085] The preparation method of the graphite negative electrode material of the present comparative example comprises the following steps:

[0086] S1. Dry the waste graphite powder at 120°C to remove the moisture in the waste graphite powder;

[0087] S2. Crush the waste graphite powder by using a high-speed crusher to obtain fine powder, wherein the particle size of the fine powder is D50 = 14.00 ± 2.0 μm and D100 < 50 μm;

[0088] S3. Place the fine powder in step S2 in a shaper, and use the friction between the materials to unify the shape of the particle surface, so that the particles have a regular morphology similar to that of a potato.

[0089] S7. Directly graphitize the waste graphite powder at 3000°C for 7 hours, and obtain a graphite material; S8. Remove the magnetic field and sieve the graphite material obtained in step S7 to obtain a graphite negative electrode material.

[0090] The waste graphite powder in step S1 is collected from the negative electrode graphite powder of waste lithium ion batteries on the market; the waste graphite powder is not treated by the preparation method steps S4 to S6 in the present comparative example, i.e., the waste graphite powder is not modified by adding a binder and a carbon source.

[0091] Comparative Example 2

[0092] The present comparative example is different from example 3 in that the treatment in step S4 is not performed, i.e., the fine powder obtained in step 2 is directly mixed with the carbon source by sufficient grinding, and the remaining steps and components are the same as those in example 3.

[0093] Comparative Example 3

[0094] The present comparative example is different from example 3 in that the treatments in steps S5 and S6 are not performed, i.e., the material I obtained in step 4 is directly graphitized, and the remaining steps and components are the same as those in example 3.

[0095] Performance test

[0096] I. The graphite negative electrode materials prepared in examples 1-9 and comparative examples 1-3 are respectively tested for particle size, tap density, specific surface area, and ash content, and the test results are shown in Table 1.

[0097] The names and models of the instruments used in the test are as follows:

[0098] Particle size: laser particle size distribution instrument Mastersizer 3000;

[0099] Tap density: Bet tap density tester;

[0100] Specific surface area, Micro High-Bo JW-DX type;

[0101] Ash, high temperature electric furnace SX2-2.5-12.

[0102] II. The first discharge capacity and the first efficiency of the graphite negative electrode materials in Comparative Examples 1-9 and Comparative Examples 1-3 were tested by using the button cell test method, and the test results are shown in Table 2.

[0103] Button cell test method: The graphite negative electrode materials prepared in Examples 1-9 and Comparative Examples 1-3 were used as the negative electrode material, lithium metal sheet was used as the positive electrode, polypropylene porous membrane (celgard 2300) was used as the separator, and 1 mol / L LiPF6 conductive salt and DMC:DEC:EC (wt%) = 1:1:1 solvent were selected as the electrolyte. CR2032 button cells were assembled in an argon-filled dry glove box, and tested by using a new battery test system, with the voltage range being 0.001-2.0V and the charge-discharge rate being 0.1C.

[0104] Cycle performance: The charging was performed at room temperature in a constant current-constant voltage mode, with the limiting current being 1C and the terminal voltage being 2.0V. The discharging was performed in a constant current mode, with the discharging current being 1C and the cut-off voltage being 0.001V. The cycle was performed for 3000 times, and the capacity retention rate after 3000 cycles was calculated. The test results are shown in Table 2.

[0105] Table 1: Test results of Examples 1-9 and Comparative Examples 1-3

[0106]

[0107] Table 2: Performance test results of Examples 1-9 and Comparative Examples 1-3

[0108]

[0109]

[0110] Note: “-” means that the cycle number did not reach 3000 times, and the capacity retention rate was less than 80%.

[0111] Referring to Table 1 and Table 2, in combination with the test results of Examples 1-8, it can be seen that after the waste graphite battery is repaired by the process of the present application, the particle size, tap density and specific surface area of the regenerated graphite negative electrode material are all in a relatively reasonable range, and the ash content is controlled to be less than 0.05%. In terms of performance, the first efficiency of the regenerated graphite negative electrode material is improved, and the capacity retention rate is significantly improved. The capacity retention rate after 3000 cycles at room temperature 1C is all above 80%, and the cycle performance is good.

[0112] It can be seen from the detection results of Examples 1-4 and Comparative Example 3 that, compared with Comparative Example 3 without adding a carbon source, the secondary wrapping modification of the graphite powder can be performed by adding an appropriate amount of the carbon source in Examples 1-4, and the prepared regenerated graphite negative electrode material has good cycle performance. In summary, when the mass ratio of the material I to the carbon source is 100:15, the capacity retention rate of the prepared regenerated graphite negative electrode material is optimal, reaching 85.0%.

[0113] It can be seen from the detection results of Examples 3, 5-6 and Comparative Example 2 that, compared with Comparative Example 2 without adding a carbon source, the cycle performance of the battery can be improved by adding an appropriate amount of the binder to perform the granulation and wrapping modification of the waste graphite. In summary, when the mass ratio of the fine powder to the coal tar pitch is 100:5, the capacity retention rate is optimal.

[0114] It can be seen from the detection results of Examples 3, 7-9 that, by using epoxy resin to replace phenolic resin, or using pitch and furfural resin to replace coal tar pitch, the performance of the prepared regenerated graphite is better after being repaired by the process of the application.

[0115] It can be seen from the detection results of Examples 3, Comparative Examples 1-3 that the cycle performance of Comparative Example 1 is poor, which is because the lithium ion battery works to form a SEI film on the surface of the graphite, and the waste graphite material of Comparative Example 1 originally has many structural damages on the surface and inside, so the formed SEI film is unstable, and with the increase of the cycle number, the SEI film is more likely to fall off, peel off and deposit on the surface of the graphite negative electrode, which continuously consumes the electrolyte, further increases the internal resistance of the graphite negative electrode, causes heat accumulation and capacity loss, and results in poor cycle stability and low capacity retention rate. Compared with Example 3, the repair of Comparative Examples 2 and 3 is incomplete, and there is still a certain structural damage on the graphite negative electrode material, so the cycle performance is relatively poor.

[0116] In embodiment 3, the waste graphite powder is repaired by adding a binder and a carbon source. The binder effectively bonds the waste graphite powder together, granulates the graphite powder, and exhibits good fluidity in a proper temperature range, is adsorbed by the waste graphite powder and can penetrate into the interstices of the waste graphite powder, and can also wrap the graphite powder, repairing the structural damage of the waste graphite powder, granulating and wrapping the waste graphite powder. The graphite is then secondarily coated and modified by the carbon source, a hard carbon coating layer is formed on the surface of the graphite powder after carbonization, and finally graphitization is performed to form a stable structure of the hard carbon coating layer, repairing the internal and surface structural damage of the waste graphite material. Therefore, the lithium ion battery using the regenerated graphite material can form a stable and excellent SEI film on the surface of the electrode material during charging and discharging, delay the speed of SEI film peeling, peeling and depositing on the surface of the negative electrode material, slow down the capacity attenuation of the battery through lithium ion co-embedding, improve the cycle performance of the battery, prolong the cycle life, increase the service life and performance of the battery; the waste graphite material processed by the process of the application has less graphite defects and a larger SEI film area, and therefore the first efficiency is also improved.

[0117] The specific embodiments are merely illustrative of the present application, and are not intended to limit the present application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the present specification, and the modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A method for preparing a regenerated graphite anode material for long-cycle lithium-ion batteries, characterized in that, Includes the following steps: S1. Dry, pulverize, and shape the waste graphite powder to obtain fine powder; S2. Mix the fine powder described in step S1 with the binder, and heat it to 500-800°C under an inert atmosphere for 2-6 hours to obtain material I; S3. Break up material I from step S2 again, add carbon source and grind and mix thoroughly to obtain material II; S4. Carbonize material II obtained in step S3 at 700-1500℃ for 5-10 hours to obtain material III; S5. Graphitize material Ⅲ from step S4 to obtain graphite material; S6. Demagnetize and sieve the graphite material obtained in step S5 to obtain the recycled graphite anode material; In step S3, the mass ratio of material I to carbon source is 100:5-20; The binder is selected from one of asphalt, petroleum coke and furfural resin; And, the carbon source is selected from one of phenolic resin and epoxy resin; The carbon source undergoes pretreatment before use, and the pretreatment includes the following steps: (1) The carbon source and bismaleimide resin are mixed to prepare a mixture; (2) Melt the mixture obtained in step (1) and extrude it into granules.

2. The method for preparing a long-cycle lithium-ion battery regenerated graphite anode material according to claim 1, characterized in that... In step S1, the drying of waste graphite powder includes the following steps: The waste graphite powder is dried at 100-200℃ to remove the moisture.

3. The method for preparing a long-cycle lithium-ion battery regenerated graphite anode material according to claim 1, characterized in that, In step S1, the particle size of the fine powder is D50 = 14.00 ± 2.0 μm and D100 < 50 μm.

4. The method for preparing a long-cycle lithium-ion battery regenerated graphite anode material according to claim 1, characterized in that, In step S2, the mass ratio of fine powder to binder is 100:2 to 8.

5. The method for preparing a long-cycle lithium-ion battery regenerated graphite anode material according to claim 1, characterized in that, In step S5, the graphitization process includes the following steps: The material III obtained in step S4 is kept at 3000℃ for 6 to 8 hours.

6. A regenerated graphite anode material for long-cycle lithium-ion batteries, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 5.

7. A long-cycle lithium-ion battery, characterized in that, The graphite anode material provided in claim 6 is used.

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