Regenerated graphite active material and its preparation and application

Abstract

The present invention belongs to the field of waste graphite regeneration, and specifically relates to a method for preparing a regenerated graphite active material. The method comprises pre-processing waste graphite powder in an atmosphere A for a first gas-solid treatment to obtain a first-stage material. The first-stage material is then placed in an aqueous solution containing solute a and solute b for a second solvent-thermal treatment to separate and obtain two-stage materials. The second-stage material, an additive, and a carbon source are mixed and subjected to negative pressure heat treatment at a temperature T1. The mixture is then cooled to a temperature T2 and then directly contacted with a cooling medium for a cold quenching treatment to obtain the regenerated graphite active material. The present invention also includes materials obtained by the preparation method and their use in batteries. The graphite material regenerated by the method described in the present invention exhibits excellent fast-charging and long-cycle performance.

Description

Technical Field

[0001] The present invention relates to the technical field of waste graphite regeneration, and in particular to a method for regenerating waste graphite into negative electrode material for lithium ion batteries. Background Art

[0002] Graphite, due to its stable chemical properties, high-temperature resistance, corrosion resistance, high electrical conductivity, and easy processing, is widely used in the electrical, metallurgical, defense, new energy, and chemical industries. The graphite used in these fields is primarily divided into artificial graphite and natural graphite. Artificial graphite requires initial beneficiation and purification, while natural graphite undergoes high-temperature graphitization. Therefore, the recycling of waste graphite is of great significance from the perspectives of resource recycling and environmental protection.

[0003] For recycling waste graphite, the main methods include acid treatment, alkaline treatment, and carbon coating. For example, Chinese patent publication CN118486939A discloses a carbon-coated graphite material and its preparation method using negative electrode materials and separators from waste batteries as raw materials. Specifically, it describes a treatment process in which the graphite negative electrode sheets are washed with water, acid-washed, centrifugally washed with water, dried, pre-calcined, and then screened. Another example is Chinese patent publication CN118198570A, which discloses a high-rate recycled graphite negative electrode material and its preparation method. Specifically, it describes a process in which the waste graphite negative electrode sheets are washed with dimethyl carbonate and then calcined at a medium to high temperature for purification.

[0004] In summary, although there are many methods for recycling waste graphite in the existing technology, there is still room for improvement in the product consistency, raw material compatibility, conductivity and other aspects of the existing recycled materials. In addition, external conductive agents are usually required when assembling batteries. The battery's first-cycle coulombic efficiency, energy density, lithium source loss and high-rate long-cycle performance still have room for improvement. Summary of the Invention

[0005] In response to the problems faced by existing waste graphite recycled materials, the first purpose of the present invention is to provide a method for preparing recycled graphite active materials, aiming to prepare recycled graphite materials with good consistency and excellent coulombic efficiency, energy density and high-rate long-cycle performance without the need for auxiliary conductive agents.

[0006] The second purpose of the present invention is to provide a regenerated graphite active material obtained by the preparation method and its application in lithium ion batteries.

[0007] The third object of the present invention is to provide a lithium-ion battery comprising the regenerated graphite active material, and a negative electrode and a negative electrode material thereof.

[0008] During the conventional electrode production process, 2-5% of highly conductive carbon materials such as conductive carbon black or carbon nanotubes need to be added. These additives generally have a high production cost (such as carbon nanotubes), and the addition of conductive carbon will reduce the proportion of active materials, affecting the energy density of the battery. In addition, the addition of conductive carbon to the electrode will make it difficult to recycle graphite from waste batteries, and a certain process is required to remove the conductive carbon to improve the purity of the recycled graphite. Therefore, through extensive research, the present invention provides the following preparation process for recycled graphite materials that can obtain excellent performance without the need for auxiliary conductive agents, as follows:

[0009] A method for preparing a regenerated graphite active material, comprising the following steps:

[0010] Step (1): Gas and liquid two-stage processing

[0011] The waste graphite powder is preliminarily subjected to a first gas-solid treatment in atmosphere A to obtain a first-stage material; the first-stage material is then placed in an aqueous solution containing solute a and solute b for a second solvent thermal treatment to separate and obtain two-stage materials;

[0012] The atmosphere A contains at least one functional gas selected from oxygen, carbon dioxide, and ammonia; the temperature of the first gas-solid treatment is 350-600°C;

[0013] Solute a is able to ionize into H in water + The solute b comprises ferrite;

[0014] Step (2):

[0015] The second-stage material, the additive, and the carbon source are mixed and subjected to negative pressure heat treatment at temperature T1, and then cooled to temperature T2 and directly contacted with a cooling medium for cold quenching to obtain the regenerated graphite active material;

[0016] The auxiliary agent is one or more of cobalt acetylacetonate, nickel acetylacetonate, cobalt naphthenate, nickel naphthenate, cobalt acetate, nickel acetate, dicobalt octacarbonyl, cobalt oxalate, nickel oxalate, and nickel benzoate;

[0017] The temperature T1 is above 700°C, and the temperature T2 is between 300 and 600°C.

[0018] The present invention innovatively subjects the waste graphite to the aforementioned gas and liquid two-stage treatment in advance, and further coordinates the atmosphere of the gas-solid treatment stage, the solute components of the liquid phase treatment stage, and the combination of negative pressure heat treatment and cold quenching processes assisted by additives. This can improve the purification effect of graphite, and can obtain recycled graphite materials with a purity of more than 99.99% and excellent performance. For example, the recycled graphite material described in the present invention can be assembled without the assistance of a conductive agent to obtain a battery with excellent first efficiency, fast charging, and long cycle stability.

[0019] In the present invention, the waste graphite powder is waste batteries, waste graphite crucibles, waste graphite electrodes, and waste graphite generated in the semi-conductive industry and the smelting industry.

[0020] In the present invention, in order to improve the efficiency and value of the regeneration process, the graphitization degree of the waste graphite powder can be above 82%, and the fixed carbon content can be above 80%.

[0021] In the present invention, the particle size of the waste graphite powder can be pre-controlled to be between D50=3 and 18 μm.

[0022] In the present invention, the waste graphite powder is subjected to the gas phase treatment in advance and then to the liquid phase treatment, and the conditions of the gas phase-liquid phase treatment are further coordinated and controlled. This can significantly optimize the surface and interlayer physicochemical characteristics of the graphite, and then combine with subsequent processes to improve the electrochemical properties of the regenerated graphite in the absence of a conductive agent, especially the long cycle performance under fast charging and high rate.

[0023] In the present invention, the functional gas in the atmosphere A is oxygen, with a content of 10-40% by volume, or air. The functional gas is carbon dioxide, with a content of 5-20% by volume, or ammonia, with a content of 2-8% by volume.

[0024] In the atmosphere A, the functional gas is a mixture of oxygen and ammonia in a volume ratio of 1 to 5:1. The content of the mixed functional gas in the atmosphere A may be 10 to 25%.

[0025] The atmosphere A further comprises a diluent gas, and the diluent gas comprises at least one of air, argon, helium, and nitrogen.

[0026] In the present invention, the time of the first gas-solid treatment is 4 to 12 hours, and can further be 5 to 10 hours.

[0027] In the present invention, the solute a includes one or more of hydrochloric acid, sulfuric acid, and nitric acid.

[0028] In the solute b, the ferrite includes at least one of sodium ferrite, potassium ferrate, potassium ferrate, and zinc ferrite.

[0029] Preferably, the solute b further comprises at least one auxiliary solute b1 selected from ammonium ferric citrate, ferric ammonium sulfate, and ferric acetate. Studies have shown that the combination of solute b1 and ferrite can optimize the interlayer and physicochemical characteristics of regenerated graphite, thereby optimizing its fast-charging performance.

[0030] Preferably, in the solute b, the solute b1 accounts for 1 to 15% by weight of the ferrite.

[0031] In the present invention, in the aqueous solution, the concentration of the solute a is 0.1-2M, and can further be 0.2-1M; the concentration of the solute b is 0.1-2M, and can further be 0.1-0.5M.

[0032] In the present invention, the aqueous solution may contain a water-soluble organic solvent; more preferably, at least one of methanol, ethanol, acetone, isopropyl alcohol, n-propyl alcohol, and acetic acid. Studies have shown that adding a certain amount of water-soluble organic solvent to the aqueous solvent can further optimize the material's physicochemical structure and enhance its fast charging and long-cycle stability.

[0033] In the present invention, the liquid-to-solid ratio of the first-stage material and the aqueous solution can be reasonably adjusted according to needs, and can be 5 to 20 mL / g in consideration of cost.

[0034] Preferably, the first-stage material and the aqueous solution are pre-ultrasonicated and then placed in a sealed container and heated for the second stage of solvent thermal treatment. In the present invention, the first-stage material is pre-ultrasonicated in the aqueous solution, and then further subjected to the subsequent solvent thermal treatment, which helps to further strengthen the surface and interlayer structure of the recycled material, and can further enhance its fast charging and long-cycle stability.

[0035] The temperature of the second stage solvent thermal treatment is above 100°C, and further between 100 and 150°C.

[0036] The time of the second solvent thermal treatment is 4 to 12 hours.

[0037] In the present invention, the additive comprises dicobalt octacarbonyl and optionally comprises one or more of nickel acetylacetonate, nickel naphthenate, nickel acetate, nickel oxalate, and nickel benzoate. Furthermore, the weight content of dicobalt octacarbonyl in the additive is 30-60 wt.%. Studies have shown that the combination of dicobalt octacarbonyl and nickel can strengthen the interlayer and surface properties of graphite, and optimize its rate and long-cycle performance.

[0038] In the present invention, the weight ratio of the second-stage material to the auxiliary agent is 100:0.2-5, and can further be 100:1-2.

[0039] In the present invention, the carbon source can be a carbon-containing organic matter well known in the industry, for example, it can include one or more of common asphalt, polypropylene, phenolic resin, starch, ethylenediamine, polyethylene glycol, glucose, and sucrose.

[0040] In the present invention, the weight ratio of the second-stage material to the carbon source is 100:5-15, and can further be 100:8-12.

[0041] In the present invention, the second-stage material, additives, and carbon source are mixed under positive pressure in the liquid phase, followed by a desolventizing treatment to obtain a mixture, which is then subjected to a subsequent negative pressure heat treatment. Research in the present invention also shows that pre-combining the second-stage material, additives, and carbon source under positive pressure can further enhance the combined synergy of the components, helping to further strengthen the physical and chemical characteristics of the recycled material's surface and interlayers, and further enhancing its fast-charging and long-cycle performance.

[0042] In the present invention, the pressure in the positive pressure mixing stage is above 5 atm (atm refers to standard atmospheric pressure), and can further be 5 to 15 atm.

[0043] In the present invention, the pressure in the negative pressure heat treatment stage may be below 0.5 atm, and may be 1 to 100 Pa in consideration of equipment cost.

[0044] In the present invention, the temperature of the negative pressure heat treatment may be 1000 to 1400°C, and further may be 1000 to 1200°C.

[0045] Preferably, the negative pressure heat treatment time is 4 to 15 hours, and further can be 6 to 10 hours.

[0046] In the present invention, after the negative pressure heat treatment, the material may be cooled to the temperature T2 by conventional means such as in a furnace.

[0047] In a preferred embodiment of the present invention, after the negative pressure heat treatment is completed, cooling to temperature T2 can be assisted by atmosphere B. The atmosphere B is one or more of nitrogen, argon, helium, and carbon dioxide. The present invention's research also shows that using the atmosphere B to assist cooling, followed by subsequent cold quenching treatment, can synergistically optimize the surface and interlayer physicochemical characteristics of the regenerated graphite, further enhancing its fast charging and long cycle performance.

[0048] In the present invention, the cooling medium is liquid nitrogen, dry ice or water.

[0049] The present invention also provides a regenerated graphite active material prepared by the preparation method.

[0050] The preparation method described in the present invention can give the prepared material special physical and chemical characteristics, and the material prepared by the preparation method can be assembled into a negative electrode and a battery without a conductive agent. Not only that, it can also obtain excellent first efficiency, fast charging and long cycle performance at high rates.

[0051] The present invention also provides an application of the regenerated graphite active material prepared by the preparation method, which is used as a negative electrode active material for preparing an alkali metal ion battery.

[0052] In the present invention, the negative electrode active material and the binder are combined to prepare the negative electrode material without adding an external conductive agent, and the negative electrode material is used for preparing an alkali metal ion battery.

[0053] The present invention also provides a negative electrode for an alkali metal battery, comprising a negative electrode current collector and a negative electrode material composited on its surface, wherein the negative electrode material comprises a negative electrode active material and a binder, wherein the negative electrode active material comprises the regenerated graphite active material obtained by the preparation method.

[0054] In the present invention, the negative electrode material is a negative electrode without an external conductive agent, and can further be composed of a negative electrode active material and a binder.

[0055] In the present invention, in the negative electrode material, the content of the negative electrode active material is 80 to 95 wt.%.

[0056] The present invention also provides an alkali metal battery comprising the negative electrode of the present invention.

[0057] The alkali metal battery of the present invention may be, for example, a sodium ion battery or a lithium ion battery.

[0058] The alkali metal battery of the present invention, in addition to containing the regenerated graphite active material of the present invention in the negative electrode, optionally contains no conductive agent, and other components and parts can be conventional.

[0059] Beneficial effects

[0060] The present invention innovatively subjects the waste graphite to the aforementioned two-stage gas and liquid treatment in advance, and further coordinates the atmosphere of the gas-solid treatment stage, the solute components of the liquid phase treatment stage, and the combination of negative pressure heat treatment and cold quenching processes assisted by additives. This can improve the purification effect of the graphite, and can obtain high-purity regenerated graphite materials with excellent performance. For example, the regenerated graphite materials described in the present invention can be assembled without the assistance of a conductive agent to obtain a battery with excellent first efficiency, fast charging, and long-cycle stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 This is the SEM image of the raw material of Example 1;

[0062] Figure 2 This is the SEM image of the product of Example 1;

[0063] Figure 3 This is the first charge-discharge curve (0.2C) of the sample obtained in Example 1;

[0064] Figure 4 This is the cycle diagram of the sample obtained in Example 1 at 6°C / room temperature; DETAILED DESCRIPTION

[0065] The following examples illustrate the specific steps of the present invention. It should be understood that these examples are only for illustration of the present invention and are not intended to limit the scope of the present invention in any way. Various processes and methods not described in detail in the present invention are conventional methods well known in the art.

[0066] The method of the present invention can be applied to waste graphite from any source. In the following case, as a typical embodiment, the waste graphite negative electrode material from waste batteries is obtained by conventional current collector stripping, and its graphitization degree can be 88±2%; the fixed carbon content is 93±2%.

[0067] Example 1

[0068] Step 1: Place the waste graphite powder in an atmosphere furnace and keep it in atmosphere A (air) at a temperature of 450±10℃ for 6 hours to obtain a first-stage material;

[0069] Step 2: The first-stage material is mixed with solution A (which comprises an aqueous solution of 0.2M hydrochloric acid (solute a) and 0.1M sodium ferrite (solute b)) at a liquid-solid ratio of 5ml / g, and then ultrasonicated at 200W for 0.5-1h. The mixture is then loaded into a high-pressure reactor (filling volume is 70-80%) and heated to 110°C (solvent thermal temperature) for 6h. The mixture is then solid-liquid separated, and the filter cake is dried and dispersed to obtain the second-stage material.

[0070] Step 3: Asphalt, additive (octacarbonyl dicobalt) and second-stage material are mixed in a weight ratio of 10:1:100 to obtain a mixture, which is then kept at a negative pressure of less than 50 Pa and a temperature of T1 (1200±50°C) for 6 hours. The mixture is then cooled to T2 (450±50°C) with the furnace and mixed with liquid nitrogen (cooling medium) for cold quenching to obtain the regenerated graphite active material.

[0071] Example 2

[0072] Compared with Example 1, the only difference is that the conditions of step 1 are changed. The experimental groups are:

[0073] Group A: Change the type of atmosphere A to 15% oxygen + 5% ammonia, with the balance being nitrogen;

[0074] Group B: change the temperature of step 1 to 400±10℃ and keep it for 8h;

[0075] Other operations and parameters are the same as in Example 1.

[0076] Example 3

[0077] Compared with Example 1, the only difference is that the conditions of step 2 are changed. The experimental groups are:

[0078] Group A: Solution A was changed to 1 M nitric acid and 0.5 M potassium ferrite; the solvothermal temperature was 130 °C and the holding time was 5 h;

[0079] Group B: Solute b was further added with ferric acetate at 8% of the weight of sodium ferrite, and the concentration of solute b in the solution was the same as in Example 1;

[0080] Group C: ethanol was added to solvent A, where the volume ratio of ethanol to water in solution A was 0.1:1;

[0081] Other operations and parameters are the same as in Example 1.

[0082] Example 4

[0083] Compared with Example 1, the only difference is that the conditions in step 3 are changed. The experimental groups are:

[0084] Group A: The additive is nickel acetate;

[0085] Group B: The auxiliary agent is a mixture of dicobalt octacarbonyl and nickel acetate, with a mass ratio of 1:1; the amount of total auxiliary agent used is the same as in Example 1;

[0086] Group C: The weight ratio of asphalt, additives and second-stage material is 8:2:100, the temperature of T1 is 1050±50℃, and the insulation time is 10h; the temperature of T2 is 500±50℃, and the cooling medium is dry ice.

[0087] Group D: Asphalt, additives, and second-stage material were slurried with ethanol (liquid-to-solid ratio of 2 ml / g) and stirred at 5 atm for 1 h. The solvent was then evaporated to obtain a mixture, which was then subjected to subsequent negative pressure heat treatment and cold quenching treatment;

[0088] Group E: After keeping at temperature T1, it was cooled to temperature T2 using carbon dioxide atmosphere;

[0089] Other operations and parameters are the same as in Example 1.

[0090] Comparative Example 1

[0091] Compared with Example 1, the only difference is that in step 1, the atmosphere A is Ar, and the other operations and parameters are the same as Example 1.

[0092] Comparative Example 2

[0093] Compared with Example 1, the only difference is that, in step 2, in solution A, potassium permanganate is used in an equimolar amount to replace the sodium ferrite, and other operations and parameters are the same as in Example 1.

[0094] Comparative Example 3

[0095] Compared with Example 1, the only difference is that in step 2, the temperature of the treatment stage is controlled to 60° C. Other operations and parameters are the same as in Example 1.

[0096] Comparative Example 4

[0097] Compared with Example 1, the only difference is that the waste graphite powder is first used as the raw material for the treatment of step 2, the obtained product is used as the raw material for the treatment of step 1, and the obtained material is then subjected to step 3 and subsequent treatments. Other operations and conditions are the same as in Example 1.

[0098] Comparative Example 5

[0099] Compared with Example 1, the only difference is that, in step 3, sodium chloride or the like is used to replace the auxiliary agent by weight, and other operations and parameters are the same as those in Example 1.

[0100] Comparative Example 6

[0101] Compared with Example 1, the only difference is that in step 3, no cold quenching treatment is performed, and furnace cooling is directly performed. Other operations and parameters are the same as in Example 1.

[0102] Electrochemical performance test method:

[0103] The recycled graphite negative electrode active material and binder (LA-133, CMC) prepared in each case were evenly mixed in a mass ratio of 96:4, and then deionized water was added to make a uniform slurry, which was coated on copper foil and placed in a vacuum dryer at 120°C for 12 hours to obtain a recycled graphite negative electrode sheet without a conductive agent.

[0104] A CR2032 button battery shell was used, the obtained regenerated graphite negative electrode sheet was used as the working electrode, the metal lithium sheet was used as the counter electrode, a Celgard 2400 type diaphragm was used, nickel foam was used as the counter electrode side current collector, and a solution of ethylene carbonate + dimethyl carbonate + diethyl carbonate (EC+DMC+DEC, 1:1:1) containing 1M LiPF6 was used as the electrolyte. The batteries were assembled in a glove box under an argon atmosphere and then compressed and packaged using a sealing machine to obtain a button lithium battery.

[0105] The battery cycle performance was tested at room temperature with a test voltage range of 0.01V to 1.5V and a test rate of 0.2C and 6C. The results are shown in Table 1 and Table 2:

[0106] Table 1:

[0107]

[0108]

[0109] Table 2

[0110]

[0111] By comparing Table 1 with Table 2, the present invention uses the process described in the present invention to optimize the physical and chemical characteristics of the regenerated graphite, and to improve its rate and long-cycle effect at high rate.

[0112] In addition, compared with Example 1 and Example 2, the use of the oxygen-ammonia composite functional gas can achieve a better regenerated graphite rate and high-rate stability. As shown in Examples 1 and 3, the combination of sodium ferrite and ferric acetate can achieve a better technical synergistic effect. As shown in Examples 1 and 4, the use of an additive containing dicobalt octacarbonyl and / or pressurized compounding and carbon dioxide gas cooling can achieve better technical synergistic performance.

Claims

1. A method for preparing a regenerated graphite active material, characterized in that the steps include: Step (1): Gas and liquid two-stage processing The waste graphite powder is preliminarily subjected to a first-stage gas-solid treatment in atmosphere A to obtain a first-stage material; The first-stage material is then placed in an aqueous solution containing solute a and solute b for a second stage of solvent thermal treatment to separate and obtain two-stage materials; The atmosphere A contains at least one functional gas selected from oxygen, carbon dioxide, and ammonia; the temperature of the first gas-solid treatment is 350-600°C; Solute a is able to ionize into H in water + The solute b comprises ferrite; Step (2): The second-stage material, the additive, and the carbon source are mixed and subjected to negative pressure heat treatment at temperature T1, and then cooled to temperature T2 and directly contacted with a cooling medium for cold quenching to obtain the regenerated graphite active material; The auxiliary agent is one or more of cobalt acetylacetonate, nickel acetylacetonate, cobalt naphthenate, nickel naphthenate, cobalt acetate, nickel acetate, dicobalt octacarbonyl, cobalt oxalate, nickel oxalate, and nickel benzoate; The temperature T1 is above 700°C, and the temperature T2 is between 300 and 600°C.

2. The method for preparing the regenerated graphite active material according to claim 1, wherein: The waste graphite powder is waste graphite generated by waste batteries, waste graphite crucibles, waste graphite electrodes, semi-conductive industries and smelting industries.

3. The method for preparing the regenerated graphite active material according to claim 1, wherein: The graphitization degree of the waste graphite powder is above 82%, and the fixed carbon content is above 80%.

4. The method for preparing the regenerated graphite active material according to claim 1, wherein: The functional gas in the atmosphere A is oxygen, and its content is 10-40v%; the functional gas is carbon dioxide, and its content is 5-20v%; the functional gas is ammonia, and its content is 2-8v%.

5. The method for preparing the regenerated graphite active material according to claim 1, wherein: In the atmosphere A, the functional gas is a mixture of oxygen and ammonia in a volume ratio of 1 to 5:

1.

6. The method for preparing the regenerated graphite active material according to claim 5, wherein: The atmosphere A contains diluent gas.

7. The method for preparing a regenerated graphite active material according to claim 1, wherein: The time for the first gas-solid treatment is 4 to 12 hours.

8. The method for preparing a regenerated graphite active material according to claim 1, wherein: The solute a includes one or more of hydrochloric acid, sulfuric acid, and nitric acid.

9. The method for preparing a regenerated graphite active material according to claim 1, wherein: In the solute b, the ferrite includes at least one of sodium ferrite, potassium ferrate, potassium ferrate, and zinc ferrite.

10. The method for preparing a regenerated graphite active material according to claim 1, wherein: The solute b further includes an auxiliary solute b1 of at least one of ammonium ferric citrate, ferric ammonium sulfate, and ferric acetate.

11. The method for preparing a regenerated graphite active material according to claim 10, wherein: In solute b, solute b1 accounts for 1 to 15% of the weight of the ferrite.

12. The method for preparing a regenerated graphite active material according to claim 9, wherein: In the aqueous solution, the concentration of the solute a is 0.1-2M; the concentration of the solute b is 0.1-2M.

13. The method for preparing a regenerated graphite active material according to claim 12, wherein: The aqueous solution also contains a water-soluble organic solvent.

14. The method for preparing a regenerated graphite active material according to claim 13, wherein: In the aqueous solution, the organic solvent is at least one of methanol, ethanol, acetone, isopropanol, n-propanol, and acetic acid.

15. The method for preparing a regenerated graphite active material according to claim 12, wherein: The first stage material and aqueous solution are pre-ultrasonicated and then placed in a sealed container and heated for the second stage solvent thermal treatment.

16. The method for preparing a regenerated graphite active material according to claim 1, wherein: The temperature of the second stage solvent thermal treatment is above 100°C.

17. The method for preparing a regenerated graphite active material according to claim 16, wherein: The temperature of the second stage solvent thermal treatment is 100~150℃.

18. The method for preparing a regenerated graphite active material according to claim 1, wherein: The time of the second solvent thermal treatment is 4 to 12 hours.

19. The method for preparing a regenerated graphite active material according to claim 1, wherein: The auxiliary agent contains dicobalt octacarbonyl.

20. The method for preparing a regenerated graphite active material according to claim 19, wherein: The auxiliary agent further comprises one or more of nickel acetylacetonate, nickel naphthenate, nickel acetate, nickel oxalate and nickel benzoate.

21. The method for preparing a regenerated graphite active material according to claim 1, wherein: The weight ratio of the second-stage material to the auxiliary agent is 100:0.2~5.

22. The method for preparing a regenerated graphite active material according to claim 1, wherein: The carbon source includes one or more of asphalt, polypropylene, phenolic resin, starch, ethylenediamine, and polyethylene glycol.

23. The method for preparing a regenerated graphite active material according to claim 1, wherein: The weight ratio of the second stage material to the carbon source is 100:5-15.

24. The method for preparing a regenerated graphite active material according to claim 1, wherein: The second-stage material, the additive and the carbon source are mixed under liquid phase positive pressure, and then subjected to a desolventizing treatment to obtain a mixture, which is then subjected to a subsequent negative pressure heat treatment.

25. The method for preparing a regenerated graphite active material according to claim 24, wherein: The pressure in the positive pressure mixing stage is above 5 atm.

26. The method for preparing a regenerated graphite active material according to claim 25, wherein: After the negative pressure heat treatment is completed, the mixture is cooled to temperature T2 with the aid of atmosphere B.

27. The method for preparing a regenerated graphite active material according to claim 26, wherein: The atmosphere B includes one or more of nitrogen, argon, helium and carbon dioxide.

28. The method for preparing a regenerated graphite active material according to claim 1, wherein: The cooling medium is liquid nitrogen, dry ice or water.

29. A regenerated graphite active material obtained by the preparation method according to any one of claims 1 to 28.

30. An application of a regenerated graphite active material obtained by the preparation method according to any one of claims 1 to 28, characterized in that: It is used as negative electrode active material to prepare alkali metal ion batteries.

31. The use according to claim 30, characterized in that The negative electrode active material and the binder are combined to prepare a negative electrode material without an external conductive agent, and the negative electrode material is used for preparing an alkali metal ion battery.

32. A negative electrode for an alkali metal battery, comprising a negative electrode current collector and a negative electrode material composited on the surface thereof, wherein the negative electrode material comprises a negative electrode active material and a binder, characterized in that: The negative electrode active material includes the regenerated graphite active material prepared by the preparation method according to any one of claims 1 to 28.

33. The negative electrode of the alkali metal battery according to claim 32, wherein The negative electrode material consists of a negative electrode active material and a binder.

34. The negative electrode of the alkali metal battery according to claim 32 or 33, wherein: In the negative electrode material, the content of the negative electrode active material is 80-95 wt.%.

35. An alkali metal battery, characterized in that A negative electrode comprising the negative electrode according to any one of claims 32 to 34.

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