Waste graphite regenerative material, preparation and application thereof

Abstract

The application belongs to the field of waste battery recycling, and particularly relates to a waste graphite regenerated material and a preparation and application thereof. The preparation method is as follows: waste graphite powder and a nitrate of metal M are subjected to first-stage modification treatment under microwave assistance to obtain first-stage modified material; the metal M comprises at least one of a first main group metal element and a transition metal element; the first-stage modified material is placed in a modification liquid containing acid and an oxidizing agent to be subjected to second-stage modification treatment, and second-stage modified material is collected; the second-stage modified material, an additive A, an additive B and a carbon source are mixed and heated to be subjected to third-stage modification treatment, and then are washed and dried to obtain the waste graphite regenerated material; the additive A is a magnesium-based chloride; and the additive B is a metal N fluoride. The regenerated material has super-fast charging and low-temperature cycle performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of waste graphite high-value utilization, and particularly relates to efficient purification of waste graphite and recycling thereof. BACKGROUND

[0002] Graphite is applied in many fields due to its superior performance, such as aluminum electrolysis, lithium ion batteries, semiconductors, graphite crucibles. With the increase of the use amount, efficient recovery and high-value utilization of graphite are of great significance for the recycling use of graphite.

[0003] The existing regeneration means of waste graphite mainly lies in purification and carbon coating repair. For example, the Chinese patent document with the publication number CN119143125A discloses a segmented purification method of natural graphite, specifically, the natural graphite is mixed and ground with sodium hydroxide, rapidly cooled after microwave treatment, and then subjected to microwave treatment again after hydrofluoric acid circulation treatment to obtain high-purity graphite product. Again, the Chinese patent document with the publication number CN118164482A discloses a method for recycling graphite from waste batteries, which includes the following steps: taking the graphite powder on the waste battery and pre-treating it by heat treatment, then modifying it by acid treatment, and then coating it with carbon to obtain a regenerated material.

[0004] In summary, the existing regeneration process idea of waste graphite mainly lies in carbon coating repair after acid purification, which can well improve the purity of waste graphite and form a repair interface on the surface, but the existing process is difficult to realize deep purification of graphite, in addition, the damaged interface of graphite is difficult to effectively modify, and the interface fusion between the coating interface and the graphite needs to be further improved, which will affect the performance of the regenerated graphite, especially the super-fast charging and ultra-low temperature stability of the regenerated graphite. Not only that, the existing technology also cannot avoid the environmental problems of a large amount of waste acid. SUMMARY

[0005] In view of the problems that the existing waste graphite regeneration material is difficult to be deeply repaired and is difficult to regenerate a material that takes into account super-fast charging and low-temperature performance, the first object of the present application is to provide a preparation method of waste graphite regeneration material, which aims to provide a method that can realize deep repair and can prepare a regenerated graphite material that takes into account excellent super-fast charging and low-temperature performance.

[0006] The second object of the present application is to provide a waste graphite regeneration material prepared by the preparation method and applications thereof.

[0007] The third object of the present application is to provide an alkali metal ion battery containing the waste graphite regeneration material.

[0008] A preparation method of a waste graphite regeneration material, the steps comprising:

[0009] Step 1:

[0010] The waste graphite powder and the nitrate of metal M are subjected to a first modification treatment under microwave assistance to obtain a first modified material; the metal M includes at least one of a first main group metal element and a transition metal element.

[0011] Step 2:

[0012] The first modified material is placed in a modification liquid containing an acid and an oxidizing agent to perform a second modification treatment, and a second modified material is collected.

[0013] Step 3:

[0014] The second modified material, an additive A, an additive B and a carbon source are mixed and heated to perform a third modification treatment, and then washed and dried to obtain the waste graphite regenerated material; the additive A is a magnesium-based chloride, and the additive B is a metal N fluoride.

[0015] The present application shows that the waste graphite powder is subjected to microwave-assisted treatment of the nitrate of metal M, which can dredge and loosen the interlayer, selectively optimize the graphite ratio and surface structure, and further cooperate with the subsequent second modification and the third modification treatment of the additive A and the additive B, which can realize synergy, deeply repair the graphite surface structure, improve the interlayer and graphite content, and further improve the super-fast charging and low-temperature cycle performance of the regenerated material. The regeneration method of the present application does not need excessive waste acid and cannot be coated with carbon, which has good environmental advantages.

[0016] In the present application, the waste graphite powder is collected from at least one of waste batteries, waste electrolytic devices and waste graphite crucibles.

[0017] Preferably, the content of graphite in the waste graphite powder is more than 80 wt.%.

[0018] In the present application, the waste graphite is subjected to a first modification treatment under the dual action of the nitrate of metal M and microwave, which can dredge the interlayer of graphite, improve the surface structure and optimize the graphite content, which is beneficial to the subsequent process and significantly improves the low-temperature and super-fast charging performance of the prepared material.

[0019] In the present application, the nitrate of metal M includes at least one of potassium nitrate, sodium nitrate, lithium nitrate, cobalt nitrate, nickel nitrate and iron nitrate.

[0020] Preferably, the mass ratio of the nitrate of metal M to the waste graphite powder is 0.001-0.1:100, and further can be 0.04-0.08:100.

[0021] Preferably, the microwave power is 500-2500W, and further can be 1000-2000W.

[0022] Preferably, the microwave time is 0.5-2h.

[0023] In the present application, the microwave treatment stage is carried out in a protective atmosphere, the heating rate is 100-200℃ / min, and the temperature can be 800-2000℃.

[0024] In the present application, in step 2, the acid includes a strong inorganic acid, which can be hydrochloric acid.

[0025] Preferably, the oxidizing agent includes one or more of FeCl3, SnCl4, perchloric acid, and perchlorate.

[0026] Preferably, in the modification liquid, the concentration of the acid solution is 0.01-2M, and further can be 0.02-0.05M.

[0027] Preferably, in the modification liquid, the mass ratio of the oxidizing agent to the waste graphite powder is 0.01-0.2:100, and further can be 0.01-0.02:100.

[0028] Preferably, the treatment temperature of the second-stage modification is 25-80℃.

[0029] Preferably, the treatment time of the second-stage modification is 2-8h.

[0030] In the present application, the second-stage modified material and the additives A and B are innovatively combined for heat treatment, which can further optimize the interlayer and surface structures, and is beneficial to improving the fast charging and low-temperature performance of the prepared material.

[0031] In the present application, the additive A includes one or more of magnesium chloride, methyl magnesium chloride, propyl magnesium chloride, ethyl magnesium chloride, magnesium chloride hexahydrate, octyl magnesium chloride, potassium magnesium chloride, cyclohexyl magnesium chloride, dodecyl magnesium chloride, and octadecyl magnesium chloride.

[0032] Preferably, the metal N includes at least one of calcium, magnesium, aluminum, and sodium.

[0033] Preferably, the weight ratio of the additive A, the additive B, and the second-stage modified material is 0.2-2:0.002-1:100, and further can be 0.5-1:0.02-0.1:100.

[0034] In the present application, the carbon source can be any hard carbon source and / or soft carbon source, for example, can be glucose, pitch, polymer, etc. The amount of the carbon source can be reasonably controlled according to conventional principles, for example, the amount thereof can be 1-15 wt.% of the weight of the modified material, and further can be 5-10 wt.%.

[0035] In the present application, the third modification treatment includes two insulation processes, wherein the temperature of the first insulation process is 600-950℃, and further can be 700-900℃; the temperature of the second insulation process is 1200-1500℃, and further can be 1300-1400℃.

[0036] Preferably, the insulation time of the first insulation process is 2-6h; the insulation time of the second insulation process is 2-6h.

[0037] In the present application, the atmosphere of the third modification stage is a protective atmosphere.

[0038] Preferably, the atmosphere of the system in the first insulation stage is changed to a hydrogen-containing atmosphere. The hydrogen-containing atmosphere is a mixture of hydrogen and dilution gas, and the dilution gas is at least one of, for example, nitrogen, inert gas. The hydrogen content of the hydrogen-containing atmosphere is, for example, 1-5v%.

[0039] The present application research shows that, on the basis of the combined modification process of the first stage-third stage, further using a hydrogen-containing atmosphere for the first insulation treatment, which is helpful for further and other process combined synergy, and is helpful for further improving the fast charging and low temperature performance of the prepared regenerated graphite material.

[0040] Preferably, the atmosphere of the heating process of the first insulation temperature to the second insulation temperature and the insulation stage of the second insulation stage is a halogenated hydrocarbon-containing atmosphere.

[0041] Research also shows that, under this preferred process, it is helpful for further and other process combined synergy, and is helpful for further improving the fast charging and low temperature performance of the prepared regenerated graphite material.

[0042] Preferably, the halogenated hydrocarbon is a C1-C2 alkane containing at least one substituent of Cl, F.

[0043] The halogenated hydrocarbon-containing atmosphere also contains dilution gas, and the dilution gas is at least one of, for example, nitrogen, inert gas. In the halogenated hydrocarbon-containing atmosphere, the halogenated hydrocarbon content is, for example, 1-5v%.

[0044] Preferably, after the second insulation is completed, the system is set to negative pressure, and after maintaining the negative pressure for 0.5-2h, the atmospheric pressure is restored for cooling.

[0045] The research also shows that, under the preferred pressure transformation annealing, it is helpful to further combine and synergize with other processes, and it is helpful to further improve the fast charging and low temperature performance of the prepared regenerated graphite material.

[0046] Preferably, the cleaning process includes water washing and alcohol washing processes.

[0047] The application also provides a waste graphite regenerated material prepared by the preparation method.

[0048] The preparation method can endow the regenerated material with special physicochemical characteristics, and the regenerated material with the characteristics prepared by the preparation method can unexpectedly have excellent fast charging and low temperature performance.

[0049] The application also provides an application of the waste graphite regenerated material prepared by the preparation method, which is used as an active material to prepare a negative electrode of an alkali metal ion battery.

[0050] In the application, the waste graphite regenerated material can be used as a negative electrode active material, and a negative electrode required for preparation can be prepared based on existing conventional principles and means.

[0051] The application also provides an alkali metal ion battery comprising the waste graphite regenerated material prepared by the preparation method.

[0052] In the application, the alkali metal lithium ion battery can be conventional in other components and structure keys except for the waste graphite regenerated material.

[0053] Advantages

[0054] The application innovatively performs microwave-assisted treatment on the nitrate of the metal M of the waste graphite powder, further cooperates with the second modification and the third modification treatment of the additive A and the additive B, can realize synergy, can deeply repair the surface structure of the graphite, improve the interlayer and the graphite content, and not only this, but also can improve the super fast charging and low temperature cycle performance of the regenerated material.

[0055] The research of the application also shows that the innovative joint control of the atmosphere of the third modification helps to further realize the deep repair of the graphite, and helps to further improve the super fast charging and low temperature cycle stability. BRIEF DESCRIPTION OF DRAWINGS

[0056] Figure 1 The SEM image of the waste graphite raw material of Example 1.

[0057] Figure 2 The SEM image of the regenerated graphite material prepared in Example 1.

[0058] Figure 3The XRD pattern of the regenerated graphite material prepared in Example 1. DETAILED DESCRIPTION

[0059] In the present application, the waste graphite can be any graphite material with recycling value. For example, the graphite selected in the present application can refer to the waste graphite material stripped from waste lithium ion batteries.

[0060] In the present application, the preferred recycling process can include:

[0061] First step: raw material powdering pretreatment

[0062] The waste graphite material is ground and pretreated.

[0063] The grinding treatment in step one is grinding and sieving by using a conventional crusher, and the powder with a particle size of d50=5-35 μm is selected.

[0064] Second step: microwave treatment

[0065] The waste graphite powder and metal nitrate are mixed in a certain proportion and placed in a microwave oven for microwave treatment.

[0066] The metal nitrate in step two is one or more of potassium nitrate, sodium nitrate, lithium nitrate, cobalt nitrate, nickel nitrate, and iron nitrate, and the mass ratio of nitrate to graphite powder is 0.001-0.1:100; the microwave power for microwave treatment is 500-2500 W, the microwave time is 0.5-2 h, and the microwave atmosphere is a protective atmosphere such as nitrogen or argon.

[0067] Third step: wet treatment

[0068] The above material is placed in a hydrochloric acid solution and added with an oxidizing agent for wet purification, followed by solid-liquid separation, washing, and drying.

[0069] The concentration of hydrochloric acid in step three is 0.01-2 M; the oxidizing agent is one or more of high-valence metal cation chlorides (FeCl3 and SnCl4) or perchloric acid and perchlorate. Among them, the mass ratio of oxidizing agent to graphite powder is 0.01-0.2:100. The treatment temperature is 25-80℃, and the treatment time is 2-8 h.

[0070] Fourth step: heat treatment

[0071] Additive A and additive B are added to the graphite material obtained in the above step, mix uniformly, and then place in an atmosphere furnace for heat treatment.

[0072] The additive A in step four is one or more of magnesium chloride, methyl magnesium chloride, propyl magnesium chloride, ethyl magnesium chloride, magnesium chloride hexahydrate, octyl magnesium chloride, potassium magnesium chloride, cyclohexyl magnesium chloride, dodecyl magnesium chloride, and octadecyl magnesium chloride, and the additive B is one or more of calcium fluoride, magnesium fluoride, aluminum fluoride, and sodium fluoride. The mass ratio of the additive A to the graphite is 0.2-2:100, and the mass ratio of the additive B to the graphite is 0.002-1:100. The heat treatment is as follows: the furnace charge is heated to 600-950°C in a protective gas such as nitrogen, argon, or helium, hydrogen is then introduced for 2-6h, freon gas is then introduced for continuous heating to 1200-1500°C, and the system is maintained at constant temperature for 2-6h, then the system is pumped to a vacuum state with a vacuum degree of 20-200Pa, and the system is then naturally cooled to room temperature in a protective gas such as nitrogen, argon, or helium.

[0073] Step five: cleaning of the powder

[0074] The obtained material is dispersed in water, ethanol, and water in sequence, and is thoroughly washed, and then is subjected to solid-liquid separation and drying, so that high-purity graphite powder with a purity of 99.99% or more is obtained.

[0075] The specific steps of the present application are illustrated by the following examples, and it should be understood that these examples are only for illustrating the present application, and do not limit the scope of the present application in any way. Various processes and methods not described in detail in the present application are conventional methods known in the art.

[0076] Example 1

[0077] (1) The lithium ion battery waste negative electrode powder (fixed carbon content of 88.7%, SEM image shown in Figure 1 ) is crushed and sieved, and the powder with a particle size of d50=12-28μm is collected.

[0078] (2) The above powder is mixed with a nitrate (sodium nitrate) at a mass ratio of 100:0.05, and is then placed in a microwave oven, and is treated at a power of 2000W and a microwave temperature of 1500(±50)℃ for 1h, and is then naturally cooled to room temperature.

[0079] (3) The obtained material is placed in a 0.02M hydrochloric acid solution, and an oxidizing agent (potassium perchlorate) with a weight of 0.01% of the powder obtained in step 2 is added, and is stirred at a temperature of 60°C for 4h, and is then subjected to solid-liquid separation, washing of the filter cake, and drying.

[0080] (4) The obtained material is added with 0.5% of additive A (magnesium chloride), 0.02% of additive B (calcium fluoride) and glucose (5% of the weight of the material obtained in step 3), and the furnace charge is heated to 750°C (temperature T1) under nitrogen protective gas, and is kept for 4h (time t1), heated to 1300°C (temperature T2) and kept for 4h (time t2), and then cooled to room temperature.

[0081] (5) The obtained material is dispersed in water, ethanol and water in sequence, washed thoroughly, and then solid-liquid separated and dried to obtain the waste graphite regenerated material (SEM is shown in Figure 2 , and XRD is shown in Figure 3 ). The purity of the obtained graphite is 99.992%.

[0082] Example 2

[0083] Compared with Example 1, the only difference is that the conditions of step 2 are changed, specifically, the type of nitrate salt is changed, specifically:

[0084] A: the nitrate salt is potassium nitrate;

[0085] B: the nitrate salt is cobalt nitrate.

[0086] The other operations and parameters are the same as those in Example 1.

[0087] Example 3

[0088] Compared with Example 1, the only difference is that the conditions of step 4 are changed, and the additive A and the additive B are changed, and the experimental groups are as follows:

[0089] Group A: the additive A is propyl magnesium chloride;

[0090] Group B: the additive B is sodium fluoride;

[0091] Group C: the additive A is 1% of the weight of the material obtained in step 3; and the additive B is 0.1% of the weight of the material obtained in step 3.

[0092] The other operations and parameters are the same as those in Example 1.

[0093] Example 4

[0094] Compared with Example 1, the only difference is that the sintering atmosphere and process of step 4 are changed, and the experimental groups are as follows:

[0095] Group A: 3% of hydrogen is added in the atmosphere during the temperature T1 keeping stage; and the other operations and parameters are the same as those in Example 1.

[0096] Group B: on the basis of Group A, after temperature T1 holding, stop adding hydrogen gas, but add 2-3% pentafluoroethane gas until temperature T2 holding is finished; other operations and parameters are the same as in Example 1.

[0097] Group C: on the basis of Group B, after temperature T2 holding is finished, control the pressure of the system at negative pressure (vacuum degree is 50 Pa), maintain negative pressure for 1 h, then introduce nitrogen gas to maintain the system at atmospheric pressure.

[0098] Other operations and parameters are the same as in Example 1.

[0099] Example 5

[0100] (1) Crush and sieve the waste negative electrode powder of lithium ion battery (fixed carbon content is 86.8%), and collect the powder with a particle size of d50 = 20 ± 3 μm.

[0101] (2) Mix the above powder with potassium nitrate at a mass ratio of 100:0.08, and then place it in a microwave oven. After treatment at a power of 1500 W for 1.5 h, it is naturally cooled to room temperature.

[0102] (3) Place the obtained material in a 0.05 M hydrochloric acid solution, and add 0.015% of FeCl3 solution based on the weight of the obtained material. Stir at a temperature of 50°C for 5 h, then perform solid-liquid separation, wash the filter cake and dry.

[0103] (4) Add 0.6% of magnesium chloride, 0.04% of calcium fluoride and 8% of PVP based on the weight of the obtained material, and then heat the charge to 850°C in a nitrogen protective gas. Then introduce hydrogen gas (content is 2-3 v%) for holding treatment for 3 h. Then change to 1,1,1,2-tetrafluoroethane gas (content is 2-3 v%) and continuously heat to 1400°C. Maintain constant temperature for 3 h, then pump the system to vacuum state, maintain vacuum degree at 50 Pa (for 0.5 h), and then naturally cool to room temperature in a nitrogen protective gas.

[0104] (5) Disperse the obtained material in water, ethanol and water in sequence, wash thoroughly, then perform solid-liquid separation and dry.

[0105] Comparative Example 1

[0106] Compared with Example 1, the only difference is that no nitrate salt is added in step 2. Other operations and parameters are the same as in Example 1.

[0107] Comparative Example 2

[0108] Compared with Example 1, the only difference is that sodium chloride is used instead of sodium nitrate in step 2. Other operations and parameters are the same as in Example 1.

[0109] Comparative Example 3

[0110] Compared with Example 1, the only difference is that in step 2, instead of microwave irradiation, electric heating is used, and the heating temperature and other operations and parameters are the same as in Example 1.

[0111] Comparative Example 4:

[0112] Compared with Example 1, the only difference is that no oxidant was added in step 3.

[0113] All other operations and parameters are the same as in Example 1.

[0114] Comparative Example 5

[0115] Compared to Example 1, the only difference is that in step 4, sodium chloride is used instead of magnesium chloride as additive A. All other operations and parameters are the same as in Example 1.

[0116] Comparative Example 6

[0117] Compared with Example 1, the only difference is that in step 4, additive A is missing, and the missing part is made up by additive B in equal amounts. All other operations and parameters are the same as in Example 1.

[0118] Comparative Example 7

[0119] Compared with Example 1, the only difference is that in step 4, additive B is missing, and the missing part is made up by additive A in equal amounts. All other operations and parameters are the same as in Example 1.

[0120] test:

[0121] Preparation of the negative electrode to be tested: The obtained waste graphite recycled material (positive electrode active material), binder (PVDF), and conductive agent (acetylene black) are mixed and slurried in a weight ratio of 9:0.5:0.5, coated on copper foil, and dried to obtain the working electrode, wherein the areal loading of the active material is 10±0.1mg / cm2.

[0122] Battery assembly:

[0123] CR2025 coin cells were assembled in an argon-filled dry glove box using the test negative electrode as the working electrode, lithium metal as the negative electrode, 1 mol / L LiPF6 EC / EMC (volume ratio 1:1, with 10% FEC added) as the electrolyte, and a PE-PP composite membrane as the separator. Testing was conducted within a voltage range of 0.001-2.0V: capacity and coulombic efficiency were measured at 25℃ and 0.2C charge / discharge rates. Capacity at 10C was also tested. Fast-charging performance was evaluated by the capacity retention at 10C / 0.2C. Furthermore, low-temperature stability was evaluated by cycling at -10℃ and 0.2C.

[0124] The test results are shown in Table 1:

[0125] Table 1

[0126]

[0127]

[0128] It can be seen from the examples and comparative examples that the microwave-assisted treatment of the metal M nitrate in the waste graphite powder, further combined with the second modification and the third modification of the additive A and the additive B, can realize synergy, can deeply repair the surface structure of the graphite, and can improve the interlayer and the graphite content. Moreover, it can also improve the super-fast charging and low-temperature cycle performance of the regenerated material.

[0129] In addition, it can be seen from Examples 1 and 2 that the use of cobalt nitrate as the nitrate can obtain better process synergy. It can be seen from Examples 1 and 3 that the use of propyl magnesium chloride as the additive A can obtain better process synergy. It can be seen from Examples 1 and 4 that the combined control of the atmosphere and the pressure of the two-stage sintering process, especially the first stage roasting in the hydrogen-containing atmosphere, the second stage roasting in the halogen-containing atmosphere, and the negative pressure annealing, can obtain better adaptation synergy, and can further improve the super-fast charging and low-temperature cycle performance of the regenerated material.

Claims

1. A method for preparing recycled waste graphite materials, characterized in that the steps include... include: Step 1: Waste graphite powder and nitrates of metal M were subjected to a first-stage modification treatment under microwave assistance to obtain a first-stage modified material. The metal M includes at least one of Group I metal elements and transition metal elements; the microwave power is 500-2500W; the mass ratio of the nitrate of the metal M to the waste graphite powder is 0.001-0.1:100; Step 2: The first stage of modified material is placed in a modification solution containing acid and oxidant for a second stage of modification treatment, and the second stage of modified material is collected. Step 3: The second-stage modified material, additive A, additive B, and carbon source are mixed and heated for a third-stage modification treatment, followed by washing and drying to obtain the waste graphite recycled material; additive A is a magnesium-based chloride; additive B is a metallic N fluoride. The third stage of modification treatment includes two heat preservation processes. The temperature of the first heat preservation process is 600–950°C, and the temperature of the second heat preservation process is 1200–1500°C. The weight ratio of additive A, additive B and the two-stage modified material is 0.2~2:0.002~1:

100.

2. The method for preparing recycled waste graphite materials as described in claim 1, characterized in that, The waste graphite powder is derived from graphite raw materials collected from at least one of the following waste materials: waste batteries, waste electrolysis equipment, and waste graphite crucibles.

3. The method for preparing recycled waste graphite materials as described in claim 2, characterized in that, The waste graphite powder contains more than 80 wt.% graphite.

4. The method for preparing recycled waste graphite material as described in claim 1, characterized in that, The nitrate of metal M includes at least one of potassium nitrate, sodium nitrate, lithium nitrate, cobalt nitrate, nickel nitrate, and iron nitrate.

5. The method for preparing recycled waste graphite material as described in claim 1, characterized in that, Microwave time is 0.5 to 2 hours.

6. The method for preparing recycled waste graphite material as described in claim 1, characterized in that, In step 2, the acid includes strong inorganic acids.

7. The method for preparing recycled waste graphite material as described in claim 6, characterized in that, In step 2, the acid is hydrochloric acid.

8. The method for preparing recycled waste graphite material as described in claim 1, characterized in that, In step 2, the oxidant includes one or more of FeCl3, SnCl4, perchloric acid, and perchlorate.

9. The method for preparing recycled waste graphite material as described in claim 1, characterized in that, In step 2, the concentration of acid in the modified solution is 0.01–2 M.

10. The method for preparing recycled waste graphite material as described in claim 1, characterized in that, In step 2, the mass ratio of oxidant to waste graphite powder in the modified liquid is 0.001 to 0.05:

100.

11. The method for preparing recycled waste graphite material as described in claim 1, characterized in that, In step 2, the processing temperature for the second stage of modification is 25–80°C.

12. The method for preparing recycled waste graphite material as described in claim 1, characterized in that, In step 2, the processing time for the second stage of modification is 2 to 8 hours.

13. The method for preparing recycled waste graphite material as described in claim 1, characterized in that, Additive A includes one or more of the following: magnesium chloride, methyl magnesium chloride, propyl magnesium chloride, ethyl magnesium chloride, magnesium chloride hexahydrate, octyl magnesium chloride, potassium magnesium chloride, cyclohexyl magnesium chloride, dodecyl magnesium chloride, and octadecyl magnesium chloride.

14. The method for preparing recycled waste graphite material as described in claim 1, characterized in that, The metal N mentioned includes at least one of calcium, magnesium, aluminum, and sodium.

15. The method for preparing recycled waste graphite material as described in claim 1, characterized in that, The insulation time for the first insulation stage is 2 to 6 hours; the insulation time for the second insulation stage is 2 to 6 hours.

16. The method for preparing recycled waste graphite material as described in claim 1, characterized in that, The atmosphere of the system during the stage of heating to the first stage of heat preservation is a protective atmosphere.

17. The method for preparing recycled waste graphite material as described in claim 1, characterized in that, During the first heat preservation stage, the atmosphere of the system is changed to a hydrogen-containing atmosphere.

18. The method for preparing recycled waste graphite material as described in claim 1, characterized in that, The heating process from the first stage of heat preservation to the second stage of heat preservation, as well as the atmosphere during the heat preservation stage of the second stage, is an atmosphere containing halogenated hydrocarbons.

19. The method for preparing recycled waste graphite material as described in claim 18, characterized in that, The haloalkanes mentioned are C1-C2 alkanes containing at least one substituent of Cl or F.

20. The method for preparing recycled waste graphite material as described in claim 1, characterized in that, After the second stage of heat preservation is completed, the system is set to negative pressure and maintained at negative pressure for 0.5 to 2 hours before being restored to atmospheric pressure for cooling.

21. The method for preparing recycled waste graphite material as described in claim 1, characterized in that, The cleaning process includes water washing and alcohol washing.

22. A recycled waste graphite material prepared by the preparation method according to any one of claims 1 to 21.

23. The application of a recycled waste graphite material prepared by the method according to any one of claims 1 to 21, characterized in that, It is used as an active material to prepare the negative electrode of alkali metal ion batteries.

24. An alkali metal ion battery, characterized in that, This includes recycled waste graphite materials prepared by the preparation method according to any one of claims 1 to 21.

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