Waste graphite regenerated material as well as preparation and application thereof

Abstract

The invention belongs to the field of waste battery recycling, and particularly relates to a waste graphite regenerated material and preparation and application thereof.The preparation method comprises the steps that waste graphite powder and nitrate of metal M are subjected to first-stage modification treatment under the assistance of microwaves, and a first-stage modified material is obtained; the metal M comprises at least one of a first main group metal element and a transition metal element; placing the first-stage modified material in a modification liquid containing acid and an oxidizing agent, carrying out second-stage modification treatment, and collecting to obtain a second-stage modified material; and mixing and heating the second-stage modified material, an additive A, an additive B and a carbon source, carrying out third-stage modification treatment, and then washing and drying to obtain the waste graphite regenerated material. The additive A is magnesium-based chloride; and the additive B is metal N fluoride. The material obtained by regeneration has super fast charge and low-temperature cycle performance.

Description

Technical Field

[0001] The invention belongs to the technical field of high-value utilization of waste graphite, and particularly relates to efficient purification and reuse of waste graphite. Background Art

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

[0003] The existing regeneration methods of waste graphite mainly involve purification and carbon coating repair. For example, the Chinese patent document with publication number CN119143125A discloses a segmented purification method for natural graphite, which specifically comprises mixing and grinding natural graphite with sodium hydroxide, rapidly cooling after microwave treatment, and then microwave treatment after hydrofluoric acid circulation treatment to obtain a high-purity graphite product. For another example, the Chinese patent document with publication number CN118164482A discloses a method for recycling graphite from waste batteries, which comprises the following steps: taking graphite powder from waste batteries and subjecting it to preheat treatment, followed by acid modification treatment, and then subjecting it to carbon coating treatment to obtain a recycled material.

[0004] In summary, the existing recycling process of waste graphite mainly involves carbon coating and repair after acid purification. This idea can improve the purity of waste graphite and form a repair interface on the surface. However, it is difficult to achieve deep purification of graphite in the existing process. In addition, the damaged interface of graphite is difficult to effectively modify, and the interface fusion between the coating interface and graphite needs to be further improved, which will affect the performance of recycled graphite, especially the super-fast charging and ultra-low temperature stability of recycled graphite. Not only that, the existing technology is also difficult to avoid environmental problems such as a large amount of waste acid. Summary of the invention

[0005] In view of the problems that existing waste graphite recycled materials are difficult to deeply repair and difficult to regenerate to obtain materials with both super-fast charging and low-temperature performance, the first purpose of the present invention is to provide a method for preparing waste graphite recycled materials, aiming to provide a method that can achieve deep repair and produce recycled graphite materials with both excellent super-fast charging and low-temperature performance.

[0006] The second purpose of the present invention is to provide a waste graphite recycled material obtained by the preparation method and its application.

[0007] A third object of the present invention is to provide an alkali metal ion battery comprising the waste graphite recycled material.

[0008] A method for preparing waste graphite recycled materials, comprising the following steps:

[0009] Step 1:

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

[0011] Step 2:

[0012] The first stage modified material is placed in a modification liquid containing an acid and an oxidant, and a second stage modified material is collected;

[0013] Step 3:

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

[0015] The present invention shows that the microwave-assisted treatment of the nitrate of the metal M in the waste graphite powder can dredge and loosen the interlayer, and selectively optimize the graphite ratio and surface structure, and further cooperate with the subsequent second stage modification and the third stage modification treatment of the additive A and the additive B to achieve synergy, deeply repair the graphite surface structure, improve the interlayer and graphite content, and not only that, but also improve the super fast charging and low temperature cycle performance of the recycled material. The regeneration method of the present invention does not require too much waste acid, and conventional carbon coating cannot be performed, which has good environmental advantages.

[0016] In the present invention, the waste graphite powder is graphite raw material to be processed collected from at least one of waste materials including waste batteries, waste electrolysis devices and waste graphite crucibles.

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

[0018] In the present invention, the waste graphite is innovatively subjected to a first stage modification treatment under the dual action of metal M nitrate and microwaves, which can dredge the graphite layers, improve the surface structure, and optimize the graphite content, thereby facilitating the combination with subsequent processes and significantly improving the low temperature and super fast charging properties of the prepared material.

[0019] In the present invention, the nitrate of the 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 nitrate to waste graphite powder in the technology M is 0.001-0.1:100; further, it can be 0.04-0.08:100.

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

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

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

[0024] In the present invention, in step 2, the acid includes a strong inorganic acid, such as hydrochloric acid.

[0025] Preferably, the oxidant comprises FeCl 3 SnCl 4 , perchloric acid, and perchlorate.

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

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

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

[0029] Preferably, the treatment time of the second modification is 2 to 8 hours.

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

[0031] In the present invention, 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 additive A, additive B and second-stage modified material is 0.2-2:0.002-1:100; further, it can be 0.5-1:0.02-0.1:100.

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

[0035] In the present invention, the third stage modification treatment includes two stages of heat preservation processes, wherein the temperature of the first stage of heat preservation process is 600-950°C, and can further be 700-900°C; the temperature of the second stage of heat preservation process is 1200-1500°C, and can further be 1300-1400°C.

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

[0037] In the present invention, the atmosphere in 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 a diluent, and the diluent is, for example, at least one of nitrogen and an inert gas. The hydrogen content of the hydrogen-containing atmosphere is, for example, 1 to 5% by volume.

[0039] The present invention shows that, based on the combined modification process of the first to third stages, further using a hydrogen-containing atmosphere for the first stage insulation treatment helps to further coordinate with other processes and helps to further improve the fast charging and low temperature performance of the prepared regenerated graphite material.

[0040] Preferably, the atmosphere during the heating process from the first insulation temperature to the second insulation temperature and the insulation stage of the second insulation stage is an atmosphere containing halogenated hydrocarbons.

[0041] The study also shows that under this preferred process, it is helpful to further cooperate with other processes and help further improve the fast charging and low temperature performance of the prepared recycled graphite material.

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

[0043] The halogenated hydrocarbon-containing atmosphere further contains a diluent gas, and the diluent gas is, for example, at least one of nitrogen and an inert gas. In the halogenated hydrocarbon-containing atmosphere, the halogenated hydrocarbon content is, for example, 1 to 5% by volume.

[0044] Preferably, after the second stage of heat preservation is completed, the system is set to negative pressure, and the negative pressure is maintained for 0.5 to 2 hours before returning to atmospheric pressure and cooling.

[0045] The study also showed that annealing under the preferred gas pressure change can help to further cooperate with other processes and help to further improve the fast charging and low temperature performance of the prepared recycled graphite material.

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

[0047] The invention also provides a waste graphite regeneration material obtained by the preparation method.

[0048] The preparation method described in the present invention can give the recycled material special physical and chemical characteristics, and the recycled material with the characteristics obtained by the preparation method can unexpectedly take into account excellent fast charging and low-temperature performance.

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

[0050] In the present invention, the waste graphite recycled material can be used as a negative electrode active material, and based on existing conventional principles and means, it can be used to prepare the required negative electrode.

[0051] The present invention also provides an alkali metal ion battery, which comprises the waste graphite regeneration material obtained by the preparation method.

[0052] In the present invention, the alkali metal lithium ion battery, in addition to comprising the waste graphite recycled material of the present invention, other components and structural keys can be conventional.

[0053] Beneficial Effects

[0054] The present invention innovatively subjects the waste graphite powder to microwave-assisted treatment in the nitrate of the metal M, and further cooperates with the subsequent second-stage modification and the third-stage modification treatment of the combined synergy of additives A and B, which can achieve synergy, deeply repair the graphite surface structure, improve the interlayer and graphite content, and not only that, but also improve the super-fast charging and low-temperature cycle performance of the recycled material.

[0055] The present invention also shows that the innovative joint control of the atmosphere in the third stage of modification can help to further synergistically achieve deep-level repair of graphite, and help to further improve its super-fast charging and low-temperature cycle stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 This is the SEM image of the waste graphite raw material in Example 1.

[0057] Figure 2 This is the SEM image of the regenerated graphite material obtained in Example 1.

[0058] Figure 3This is the XRD pattern of the regenerated graphite material obtained in Example 1. DETAILED DESCRIPTION

[0059] In the present invention, the waste graphite can be any graphite material with recycling value. For example, the graphite selected in the present invention can refer to the waste graphite material recovered by stripping waste lithium-ion batteries.

[0060] In the present invention, the preferred recovery process may include:

[0061] Step 1: Raw material powder pretreatment

[0062] The waste graphite is pre-treated by grinding.

[0063] The grinding process described in step 1 is to grind and sieve using a conventional crusher to select powder with a particle size of d50 = 5 to 35 μm.

[0064] Step 2: Microwave Treatment

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

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

[0067] Step 3: Wet Processing

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

[0069] The concentration of hydrochloric acid in step 3 is 0.01-2M; the oxidant is a high-valent metal cation chloride (FeCl 3 With SnCl 4 ) or one or more of perchloric acid and perchlorate. The mass ratio of the oxidant to the graphite powder is 0.01-0.2:100. The treatment temperature is 25-80°C and the treatment time is 2-8h.

[0070] Step 4: Heat Treatment

[0071] Additive A and additive B are added to the graphite material obtained in the previous step, mixed evenly, and then placed in an atmosphere furnace for heat treatment.

[0072] The additive A described in step 4 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 additive A to graphite is 0.2 to 2:100, and the mass ratio of additive B to graphite is 0.002 to 1:100. The heat treatment is to heat the charge to 600 to 950°C in a protective gas such as nitrogen, argon, and helium, then pass hydrogen for insulation treatment for 2 to 6 hours, then change to Freon gas, continue to heat to 1200 to 1500°C, maintain a constant temperature for 2 to 6 hours, and then evacuate the system to a vacuum state, maintain a vacuum degree of 20 to 200 Pa, and then naturally cool to room temperature in a protective gas such as nitrogen, argon, and helium.

[0073] Step 5: Powder cleaning

[0074] The obtained material is dispersed in water, ethanol and water successively, washed thoroughly, separated into solid and liquid, and dried to obtain high-purity graphite powder with a purity of more than 99.99%.

[0075] The specific steps of the present invention are described below by way of examples. It should be understood that these examples are only for illustrating 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 known in the art.

[0076] Example 1

[0077] (1) Lithium-ion battery waste negative electrode powder (fixed carbon content 88.7%, SEM image see Figure 1 ) are crushed and sieved to collect powder with a particle size of d50 = 12 to 28 μm.

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

[0079] (3) The obtained material is placed in a 0.02M hydrochloric acid solution, and an oxidant (potassium perchlorate) is added in an amount of 0.01% by weight of the powder obtained in step 2. The mixture is stirred at 60°C for 4 hours, and then solid-liquid separation is performed, the filter cake is washed and dried.

[0080] (4) Add 0.5% of the weight 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) to the obtained material, and heat the charge to 750°C (temperature T1) in a nitrogen protective gas, keep the temperature for 4 hours (time t1), heat it to 1300°C (temperature T2) and keep the temperature constant for 4 hours (time t2), and then cool it to room temperature.

[0081] (5) The obtained material was dispersed in water, ethanol, and water successively, washed thoroughly, separated into solid and liquid, and dried to obtain the waste graphite regeneration material (SEM see Figure 2 , XRD see Figure 3 ). After testing, 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 is changed, specifically:

[0084] A: Nitrate is potassium nitrate;

[0085] B: The nitrate is cobalt nitrate.

[0086] Other operations and parameters are the same as 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. The experimental groups are:

[0089] Group A: Additive A is propylmagnesium chloride;

[0090] Group B: Additive B is sodium fluoride;

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

[0092] Other operations and parameters are the same as in Example 1.

[0093] Example 4

[0094] Compared with Example 1, the only difference is that the sintering atmosphere and process in step 4 are changed. The experimental group is:

[0095] Group A: 3v% hydrogen was added to the atmosphere during the temperature T1 insulation stage; other operations and parameters were the same as those in Example 1;

[0096] Group B: Based on Group A, after the temperature T1 is maintained, the hydrogen is stopped and 2-3% pentafluoroethane gas is added instead until the temperature T2 is maintained; other operations and parameters are the same as those in Example 1;

[0097] Group C: Based on Group B, after the temperature T2 was maintained, the pressure of the system was controlled at negative pressure (vacuum degree was 50 Pa), maintained at negative pressure for 1 hour, and then nitrogen was introduced to maintain the system at atmospheric pressure.

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

[0099] Example 5

[0100] (1) The waste negative electrode powder of lithium-ion batteries (fixed carbon content of 86.8%) was crushed and sieved to collect the powder with a particle size of d50 = 20 ± 3 μm.

[0101] (2) The above powder and potassium nitrate were mixed uniformly in a mass ratio of 100:0.08, placed in a microwave oven, treated at a power of 1500 W for 1.5 h, and then naturally cooled to room temperature.

[0102] (3) The obtained material was placed in a 0.05M hydrochloric acid solution and 0.015% FeCl by weight of the obtained material was added. 3 The solution was stirred at 50°C for 5 hours, followed by solid-liquid separation, filter cake washing and drying.

[0103] (4) 0.6% by weight of magnesium chloride, 0.04% by weight of calcium fluoride and 8% by weight of PVP were added to the obtained material, and the temperature of the furnace was raised to 850° C. in a nitrogen protective gas, and then hydrogen (content of 2-3% by volume) was introduced for insulation treatment for 3 hours, and then 1,1,1,2-tetrafluoroethane gas (content of 2-3% by volume) was introduced, and the temperature was continuously raised to 1400° C. After maintaining the constant temperature for 3 hours, the system was evacuated to a vacuum state, and the vacuum degree was maintained at 50 Pa (maintained for 0.5 hours), and then naturally cooled to room temperature in nitrogen and protective gas.

[0104] (5) The obtained material is dispersed in water, ethanol, and water in turn, washed thoroughly, and then the solid-liquid separation and drying are performed.

[0105] Comparative Example 1

[0106] Compared with Example 1, the only difference is that no nitrate 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 in step 2, sodium chloride is used to replace the sodium nitrate. 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, microwave irradiation is not performed, but electric heating is used, wherein 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 in step 3, no oxidant is added.

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

[0114] Comparative Example 5

[0115] Compared with Example 1, the only difference is that in step 4, sodium chloride is used to replace the magnesium chloride as additive A. 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 supplemented by an equal amount of additive B. 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 supplemented by an equal amount of additive A. 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) and binder (PVDF) and conductive agent (acetylene black) are mixed in a weight ratio of 9:0.5:0.5 to form a slurry, and coated on a copper foil and dried to obtain a working electrode, in which the surface loading of the active material is 10±0.1 mg / cm2.

[0122] Battery Assembly:

[0123] The negative electrode to be tested was used as the working electrode, metallic lithium as the negative electrode, 1 mol / LLiPF6 EC / EMC (volume ratio 1:1, 10% FEC added) as the electrolyte, and PE-PP composite film as the separator to assemble the CR2025 button cell in a dry glove box filled with argon. The test was carried out in the voltage range of 0.001-2.0V: the capacity and coulomb efficiency were tested at 25°C and 0.2C charge and discharge rates. The capacity at 10C was also tested. The fast charging performance was evaluated by the capacity retention rate of 10C / 0.2C. In addition, it was further cycled at -10°C and 0.2C to evaluate its low temperature stability.

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

[0125] Table 1

[0126]

[0127]

[0128] It can be seen from the embodiments and comparative examples that the microwave-assisted treatment of the metal M in the waste graphite powder in the nitrate, and further coordinated with the subsequent second-stage modification and the third-stage modification treatment of the additive A and the additive B, can achieve synergy, deeply repair the graphite surface structure, improve the interlayer and graphite content, and not only that, but also improve the super-fast charging and low-temperature cycle performance of the recycled material.

[0129] In addition, it can be seen from Examples 1 and 2 that by using cobalt nitrate as nitrate, better process synergy can be obtained. It can be seen from Examples 1 and 3 that by using propylmagnesium chloride as additive A, better process synergy can be obtained. It can be seen from Examples 1 and 4 that by jointly controlling the atmosphere and pressure of the two-stage sintering process, especially by carrying out the first stage of roasting in a hydrogen-containing atmosphere, further carrying out the second stage of roasting in a halogen-containing atmosphere, and performing negative pressure annealing, better adaptation synergy can be obtained, which can further improve the superfast charging and low-temperature cycle performance of the recycled material.

Claims

1. A method for preparing waste graphite recycled materials, characterized in that the steps include: Step 1: The waste graphite powder and the nitrate of metal M are subjected to a first stage modification treatment under the assistance of microwaves to obtain a first stage modified material; The metal M includes at least one of the first main group metal elements and transition metal elements; Step 2: The first stage modified material is placed in a modification liquid containing an acid and an oxidant, and a second stage modified material is collected; Step 3: The second stage modified material and additive A, additive B and carbon source are mixed and heated for the third stage modification treatment, and then washed and dried to obtain the waste graphite regeneration material; the additive A is magnesium-based chloride; the additive B is metal N fluoride.

2. The method for preparing waste graphite recycled materials according to claim 1, characterized in that: The waste graphite powder is graphite raw material to be processed collected from at least one of waste materials including waste batteries, waste electrolysis devices, and waste graphite crucibles; Preferably, the graphite content in the waste graphite powder is above 80wt.%.

3. The method for preparing waste graphite recycled materials according to claim 1, characterized in that: The nitrate of the metal M includes at least one of potassium nitrate, sodium nitrate, lithium nitrate, cobalt nitrate, nickel nitrate and iron nitrate; Preferably, the mass ratio of nitrate to waste graphite powder in the technology M is 0.001 to 0.1:100; Preferably, the microwave power is 500-2500W; Preferably, the microwave time is 0.5 to 2 h.

4. The method for preparing waste graphite recycled materials according to claim 1, characterized in that: In step 2, the acid comprises a strong inorganic acid, preferably hydrochloric acid; Preferably, the oxidant comprises one or more of FeCl3, SnCl4, perchloric acid, and perchlorate; Preferably, in the modified solution, the concentration of the acid solution is 0.01 to 2 M; Preferably, in the modified liquid, the mass ratio of the oxidant to the waste graphite powder is 0.001-0.05:100; Preferably, the treatment temperature of the second stage modification is 25 to 80°C; Preferably, the treatment time of the second modification is 2 to 8 hours.

5. The method for preparing waste graphite recycled materials according to claim 1, characterized in that: 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; Preferably, the metal N includes at least one of calcium, magnesium, aluminum and sodium; Preferably, the weight ratio of additive A, additive B and second-stage modified material is 0.2-2:0.002-1:

100.

6. The method for preparing recycled waste graphite material according to claim 1, characterized in that: The third stage of modification treatment includes two stages of heat preservation process, wherein the temperature of the first stage of heat preservation process is 600-950°C; the temperature of the second stage of heat preservation process is 1200-1500°C; Preferably, the insulation time of the first insulation process is 2 to 6 hours; the insulation time of the second insulation process is 2 to 6 hours.

7. The method for preparing recycled waste graphite material according to claim 6, characterized in that: The atmosphere of the system during the stage of heating to the first insulation temperature is a protective atmosphere; Preferably, the atmosphere of the system in the first insulation stage is changed to a hydrogen-containing atmosphere; Preferably, the atmosphere during the heating process from the first insulation temperature to the second insulation temperature and the insulation stage of the second insulation stage is an atmosphere containing halogenated hydrocarbons; Preferably, the halogenated hydrocarbon is a C1-C2 alkane containing at least one substituent of Cl or F; Preferably, after the second stage of heat preservation is completed, the system is set to negative pressure, and the negative pressure is maintained for 0.5 to 2 hours before returning to atmospheric pressure and cooling; Preferably, the cleaning process includes water washing and alcohol washing processes.

8. A waste graphite recycled material obtained by the preparation method according to any one of claims 1 to 7.

9. An application of waste graphite regeneration material obtained by the preparation method according to any one of claims 1 to 7, characterized in that: It is used as an active material to prepare the negative electrode of alkali metal ion batteries.

10. An alkali metal ion battery, characterized in that: The invention comprises waste graphite regeneration material obtained by the preparation method according to any one of claims 1 to 7.

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