Graphite-based recycled graphite materials from spent batteries, their preparation methods and applications

Abstract

This invention belongs to the field of waste graphite recycling, specifically relating to a method for preparing recycled graphite materials based on waste battery failure graphite. The method involves first performing a gas-solid modification on waste battery failure graphite under atmosphere A and temperature T1, followed by a second gas-solid modification under atmosphere B and temperature T2 to obtain a modified material. Atmosphere A includes a halogen-containing atmosphere, with temperature T1 above 1100℃; atmosphere B is an atmosphere containing at least one functional gas selected from oxygen and carbon dioxide, with temperature T2 between 400 and 800℃. The modified material is then subjected to rapid cooling to obtain a rapidly cooled material. The rapidly cooled material is then combined with a carbon source and subjected to carbonization to obtain the aforementioned recycled graphite material based on waste battery failure graphite. This invention also includes the recycled graphite obtained by the method and its applications. The method described in this invention can effectively improve the low-temperature performance of recycled graphite.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of waste lithium-ion battery recycling, and particularly relates to a method for repairing and regenerating failed graphite of waste lithium-ion batteries. BACKGROUND

[0002] With the popularization and application of lithium-ion batteries, waste lithium-ion batteries will become one of the main municipal solid wastes in China. The mass fraction of graphite in lithium-ion batteries is usually 12% to 21%, so a large amount of waste graphite will be generated at the same time as the increase of waste lithium-ion batteries. At present, more research is focused on the recovery of lithium resources from waste graphite. After lithium extraction, the carbon residue (failed graphite) is usually burned in a combustion chamber or directly discarded as waste residue, which leads to particulate pollution and aggravates the greenhouse effect, and is not conducive to the recycling of graphite resources.

[0003] The failed graphite of waste batteries refers to the negative electrode black powder obtained after the failed lithium-ion batteries are disassembled, screened, demagnetized and leached of metal ions. During the process of multiple cycles of charging and discharging, the surface of the graphite particles has a solid electrolyte film, and the microstructure of the graphite will form structural defects. During the process of multiple cycles of charging and discharging, the particles expand and exist in the form of powder, the structure deteriorates, and the performance deteriorates, so the failed graphite negative electrode powder cannot be directly used. In addition, impurities will be introduced into the material during the crushing and screening process of the front-end battery, which will further deteriorate the performance of the material and make it difficult to be directly reused.

[0004] In view of the problem of difficult recovery of graphite materials of waste batteries, the main idea of the prior art is to remove impurities by acid leaching, carbon coating and doping modification, etc. For example, the Chinese patent document with publication number CN115818603A discloses a method for preparing battery-grade iron phosphate from lithium iron phosphate positive electrode powder after lithium extraction by oxidation, which removes copper, aluminum and other metal impurities and negative electrode graphite by acid dissolution of the lithium iron phosphate positive electrode powder after lithium extraction by oxidation, and then using sodium sulfide and sodium silicate to carry out precipitation reaction under certain conditions. Again, the Chinese patent document with publication number CN114890414A discloses a recycling method for graphite materials in waste batteries, which comprises the following steps: (1) acid leaching of graphite materials in waste batteries, followed by washing and drying; (2) immersion in a metal salt solution and drying; (3) immersion in an alkali solution, filtration and drying; (4) hydrothermal reaction in an organic carbon source solution to form double-coated graphite material A; (5) sintering of the above-mentioned material to form double-coated graphite material B; and (6) acid washing of the double-coated graphite material B to obtain porous C-coated graphite material.

[0005] In summary, although there are many improvement schemes for waste graphite in the prior art, the performance of the regenerated material is still not ideal, and it is particularly difficult to meet the requirements of ultra-low temperature application. SUMMARY

[0006] In view of the technical defects that the existing regenerated material of failed graphite has unsatisfactory electrochemical performance, especially low-temperature cycle stability, the first object of the present application is to provide a preparation method of a failed graphite-based regenerated graphite material of a waste battery, aiming to regenerate a high electrochemical performance, especially low-temperature cycle stability, regenerated graphite material from the failed graphite of a waste battery.

[0007] The second object of the present application is to provide the failed graphite-based regenerated graphite material of a waste battery prepared by the method and the application thereof in a lithium secondary battery.

[0008] The third object of the present application is to provide a lithium secondary battery comprising the failed graphite-based regenerated graphite material of a waste battery, a negative electrode and a negative electrode material thereof.

[0009] The structure and properties of the failed graphite of a waste battery are obviously deteriorated during multiple cycles of charging and discharging, and it is difficult to repair it to meet the low-temperature cycle requirements. In view of this problem, the present application provides the following improved scheme:

[0010] The preparation method of the failed graphite-based regenerated graphite material of a waste battery comprises the following steps: pre-modifying failed graphite (also referred to as failed graphite) of a waste battery in atmosphere A and at temperature T1 for a first gas-solid modification, and then modifying the failed graphite in atmosphere B and at temperature T2 for a second gas-solid modification to obtain modified material; the atmosphere A comprises a halogen-containing atmosphere, and the temperature T1 is above 1100 DEG C; the atmosphere B is an atmosphere containing at least one functional gas selected from oxygen and carbon dioxide, and the temperature T2 is between 400 DEG C and 800 DEG C.

[0011] The modified material is subjected to rapid cooling treatment to obtain rapid cooling material.

[0012] The rapid cooling material is compounded with a carbon source and then subjected to carbonization treatment to obtain the failed graphite-based regenerated graphite material of a waste battery.

[0013] In view of the problem that the regenerated material of the failed graphite of a waste battery is difficult to meet the low-temperature application requirements, the present application innovatively modifies the failed graphite in atmosphere A first, and then modifies it in atmosphere B, further cooperates with subsequent rapid cooling and carbon coating treatment, so as to unexpectedly realize synergy, repair the physicochemical structure of the failed graphite, and build the physicochemical characteristics suitable for low-temperature applications, so as to make it suitable for low-temperature application requirements and improve its low-temperature cycle stability.

[0014] In the present application, the failed graphite of a waste battery can be a graphite-containing material obtained by peeling and separating from the positive electrode and / or the negative electrode of a waste battery.

[0015] In the present application, the separation method of the failed graphite of a waste battery is not particularly required.

[0016] In the application, the waste battery failure graphite also contains at least one of a binder, a conductive agent, an electrolyte, and a current collector.

[0017] In the application, the content of the graphite in the waste battery failure graphite is above 80 wt.%, and can be further 80-95 wt.% considering the processing process value.

[0018] In an exemplary method of the application, the waste battery failure graphite can be obtained by stripping the current collector of the graphite negative electrode.

[0019] In the application, the first-stage gas-solid modification under the atmosphere A and at the temperature T1 is innovatively performed in advance, and the second-stage gas-solid modification under the atmosphere B and at the temperature T2 is one of the keys to synergistically improve the low-temperature performance of the regenerated graphite.

[0020] In the application, the two-stage gas-solid modification process is, for example, as follows: the failure graphite is preheated to a temperature T1 in a protective atmosphere, then the atmosphere A is added to the system, the first-stage gas-solid modification is performed under the atmosphere and temperature, then the temperature is lowered to a temperature T2 in the protective atmosphere, and the second-stage modification is performed under the atmosphere B and at the temperature.

[0021] In the application, the halogen-containing atmosphere in the atmosphere A includes at least one of fluorine gas, chlorine gas, freon, and carbon tetrachloride, and is further preferably fluorine gas.

[0022] Preferably, the atmosphere A further contains a dilution gas, and the dilution gas includes at least one of nitrogen and an inert gas.

[0023] Preferably, the volume content of the halogen-containing atmosphere in the atmosphere A is 0.05-2%, and can be further 0.5-1.5%.

[0024] In the application, the temperature T1 is 1200-1800℃.

[0025] Preferably, the first-stage gas-solid modification time is 2-4h.

[0026] In the application, the atmosphere B also contains a dilution gas, and the dilution gas includes at least one of nitrogen and an inert gas.

[0027] Preferably, the volume content of the functional gas in the atmosphere B is 10-30%.

[0028] Preferably, the temperature T2 can be 550-750℃.

[0029] Preferably, the holding time at the temperature T2 is 3-6h.

[0030] In the present application, after the second section of gas-solid heat preservation modification, slightly cool down in the protective atmosphere (for example, cool down to a temperature above 300 DEG C, further can be a temperature of 300-550 DEG C), then quenching treatment is carried out in the cooling medium while hot.

[0031] In the present application, the cooling medium includes pure water, water-alcohol mixed solution or liquid nitrogen, preferably water-alcohol mixed solution. The present application research shows that the preferred alcohol aqueous solution as quenching medium can unexpectedly further and the process combined synergistically, which can be more helpful to build the low temperature adapted physicochemical structure characteristics, and further improve the low temperature performance of the prepared regenerated material. In the present application, the alcohol can be any water-soluble monohydric alcohol, dihydric alcohol or polyhydric alcohol, considering the cost, further can be C1-C4 alcohol. The proportion of the water-alcohol solution is not particularly required, which can be a homogeneous solution, further, the water content can be 40-95v%.

[0032] In the present application, the starting temperature of the pure water is 0-20 DEG C;

[0033] In the present application, the temperature of the water-alcohol mixed solution is -40-20 DEG C.

[0034] In the present application, the amount of the cooling medium in the quenching stage can be adjusted according to the need, for example, it can be above 5ml / g, further can be 10-50ml / g.

[0035] In the present application, after the quenching is completed, it can be subjected to carbon coating treatment based on the conventional process.

[0036] For example, in the present application, the carbon source can be any soft carbon and / or hard carbon raw material known in the industry, further can include at least one of pitch, tar, resin, glucose;

[0037] In the present application, the weight ratio of the quenching material and the carbon source is 100:5-12;

[0038] In the present application, the temperature of the carbonization process is 950-1350 DEG C;

[0039] In the present application, the carbonization process is treated under negative pressure. The negative pressure refers to a pressure lower than atmospheric pressure (atm), for example, can be 0.01-0.5atm.

[0040] In the present application, the carbonization time is 2-4h;

[0041] In the present application, pre-carbonization treatment is carried out before carbonization;

[0042] In the present application, the pre-carbonization temperature is 300-500 DEG C;

[0043] In the present application, the pre-carbonization time is 1-3h.

[0044] The present application also provides the waste battery failure graphite-based regenerated graphite material prepared by the preparation method.

[0045] In the present application, the preparation method can endow the regenerated material with special physicochemical structure characteristics suitable for low-temperature application requirements, and can effectively improve the electrochemical performance thereof, especially the low-temperature electrochemical performance.

[0046] The present application also includes the application of the waste battery failure graphite-based regenerated graphite material as a negative active material to prepare a negative electrode and a negative electrode material of a battery such as a lithium ion battery.

[0047] The present application also provides a graphite negative electrode material, which comprises a negative active material, a binder and a conductive agent, wherein the negative active material comprises the waste battery failure graphite-based regenerated graphite material prepared by the preparation method.

[0048] In the present application, the content of the waste battery failure graphite-based regenerated graphite material in the negative active material can be adjusted as needed, but in order to maximize the performance advantages of the regenerated graphite, the content of the regenerated graphite in the negative active material can be controlled to be more than 50wt.%.

[0049] In the present application, the components of the binder and the conductive agent can be known in the industry, and their contents can be adjusted as needed. For example, the weight ratio of the negative active material, the binder and the conductive agent is 85-100:1-15:1-15.

[0050] The present application also provides a battery comprising a negative electrode, wherein the negative electrode comprises a current collector and a negative electrode material complexed on the surface of the current collector, and the negative electrode material is the negative electrode material of the present application.

[0051] The battery of the present application can have conventional components and structures except for the negative electrode of the present application.

[0052] Advantages

[0053] The present application innovatively subjects the waste graphite negative electrode material to two-stage atmosphere treatment in atmosphere A and atmosphere B, and then innovatively performs quenching treatment in a medium, and finally performs carbon coating treatment, which is beneficial to repairing the damaged structure of the waste graphite material and forming a protective layer suitable for the pore structure, i.e., effectively modifying the damaged structure of the graphite and repairing and modifying the physicochemical properties thereof.

[0054] The research of the present application also shows that, under the combined process, further combined control of the atmosphere A, the atmosphere B and the cooling medium and the like can further realize the synergy and help to further improve the low-temperature performance of the prepared material. BRIEF DESCRIPTION OF DRAWINGS

[0055] Figure 1 SEM image of the raw material of the failed graphite negative electrode material of Example 1;

[0056] Figure 2 SEM image of the regenerated graphite sample of Example 1; DETAILED DESCRIPTION

[0057] The failed graphite of the waste battery of the present application can be the negative electrode material (such as material A) peeled off from the graphite negative electrode of the waste battery, or the residual carbon material containing graphite (such as material B) after metal leaching from the positive electrode material peeled off from the positive electrode of the waste battery, or the black powder containing material A and material B. The failed graphite of the waste battery contains 85-90wt% of graphite, and also contains the inevitable components in the electrode sheet such as conductive agent and small amount of binder, considering the process value.

[0058] The present application innovatively subjects the failed graphite negative electrode material to two-stage atmosphere treatment in atmosphere A and atmosphere B in sequence, then innovatively performs quenching treatment in the medium, and finally performs carbon coating treatment, to obtain the regenerated graphite material.

[0059] The process of the present application can include the following optional steps:

[0060] Step (1): subjecting the failed graphite to primary two-stage heat treatment in an atmosphere furnace;

[0061] Step (2): cooling the heat-treated graphite in a cooling medium while hot, and then performing dispersion and screening;

[0062] Step (3): mixing the material obtained in the above step with a liquefiable carbon source uniformly, and then subjecting to secondary heat treatment in an atmosphere furnace, to obtain the repaired graphite negative electrode material.

[0063] The primary two-stage heat treatment in step (1) is a one-stage heat treatment in atmosphere A and a two-stage heat treatment in atmosphere B in the same atmosphere furnace. First, the failed graphite material is placed in the atmosphere furnace, heated to T1 (1200-1800 ℃) under the protection of inert atmosphere such as argon, nitrogen, helium, and then mixed gas of halogen gas and the above inert gas (atmosphere A) is introduced, wherein the halogen gas is fluorine, chlorine, freon, carbon tetrachloride, and the volume fraction of halogen gas is 0.05-2%, the treatment time is 2-4 h, then the halogen gas is stopped and the inert gas is changed, and the furnace temperature is lowered to T2 (400-800 ℃) for two-stage heat treatment. When the furnace temperature is lowered to T2, the atmosphere is changed to mixed gas of inert gas containing 10-30% oxygen or carbon dioxide (atmosphere B), and the second stage of heat preservation treatment is carried out at this temperature for 3-6 h.

[0064] In step (2), the heat-treated graphite in step (1) is cooled in a cooling medium. After the second stage of heat preservation treatment in step (1) is completed, the powder is placed in a cooling medium while the temperature is still above 300 ℃. The cooling medium is pure water (0-20 ℃), a water-alcohol mixed solution (a mixed solution of water and ethanol in any system ratio, temperature -40-20 ℃), or a liquid nitrogen system, preferably a water-alcohol mixed solution (a mixed solution of water and ethanol in any system ratio, temperature -40-20 ℃) or a liquid nitrogen system. After cooling treatment, the obtained powder is dispersed and sieved.

[0065] The liquefiable carbon source precursor in step (3) is pitch, tar, resin, glucose, etc., which can be melted at a certain temperature or dissolved in water or organic solvents. The material obtained in step (2) is mixed with the liquefiable carbon source at a mass ratio of 100:5-12, and then placed in an atmosphere furnace under the protection of inert atmosphere such as nitrogen, argon, helium, heated to 300-500 ℃, vacuumized, the system pressure is 20-200 Pa, heat treated for 2 h at this temperature, then heated to 950-1350 ℃, heat treated for 2-4 h, and naturally cooled to room temperature to obtain the repaired graphite negative electrode material.

[0066] The application also includes the application of the repaired graphite negative electrode material prepared by the repair method in the preparation of lithium ion batteries.

[0067] As a typical application idea, the application also provides a negative electrode of a lithium ion battery, which comprises a current collector and a negative electrode material compounded on the surface of the current collector, wherein the negative electrode material comprises an active material, and the active material comprises the repaired graphite negative electrode material prepared by the repair method.

[0068] Preferably, the negative electrode material further comprises a binder and a conductive agent;

[0069] In the present application, the content of the repaired graphite negative electrode material in the negative electrode material is not particularly required, for example, it can be above 50 wt.%, and considering the advantages of the repaired material of the present application in low volume expansion and structural stability, the loading on the negative electrode can be increased to 90-94 wt.%.

[0070] As a solution of the same application concept, the present application also provides a lithium ion battery comprising a negative electrode containing the repaired graphite negative electrode material of the present application.

[0071] In the present application, the repaired graphite negative electrode material can be used as a negative active material, and based on known processes and principles, the desired lithium ion battery and its negative electrode and other components are prepared. That is, the lithium ion battery and its negative electrode of the present application, in addition to containing the repaired graphite negative electrode material of the present application, other components and structural components can be known.

[0072] Example 1:

[0073] Step (1): A certain amount of failed graphite was placed in an atmosphere furnace, and under the protection of argon atmosphere, the temperature was raised to T1=1500℃, then the atmosphere A (Freon / argon, volume ratio 1:99 mixed gas) was introduced, and after 3h (marked as t1) of heat treatment at this temperature, the gas was changed to pure argon gas; when the furnace temperature decreased to T2=600℃, the atmosphere was changed to atmosphere B (containing oxygen / argon, volume ratio 2:8 mixed gas), and the temperature was kept for 4h (marked as t2).

[0074] Step (2): When the furnace temperature of the above step decreased to 400-450℃ (marked as T3), the powder was placed in liquid nitrogen (liquid-solid ratio 5-10ml / g) for cooling treatment, and after cooling treatment, the obtained powder was dispersed and sieved.

[0075] Step (3): The material obtained in the above step was mixed with 8% of pitch by weight, and then heated to 350℃ in a nitrogen atmosphere furnace, and then vacuum was applied to the system (the pressure in the system was below 0.1atm), and then the temperature was kept for 2h, and then the temperature was raised to 1200℃, and then the temperature was kept for 3h, and then the system was naturally cooled to room temperature, and the repaired graphite negative electrode material was obtained.

[0076] The obtained graphite material was subjected to a coating operation: the prepared repair graphite, SBR, CMC, and conductive carbon were mixed uniformly in a mass ratio of 94:2:2:2, then a 1:1 water / ethanol mixture was added to prepare a slurry, which was then coated on a copper foil, dried, and then assembled into a lithium half-cell. The electrolyte composition was 1 M LiPF6 in DMC / EMC / EC, with the addition of 5% PC and 5% FEC. Constant current charge and discharge tests were then performed at 0.2C at room temperature 25°C, low temperature -20°C, and -40°C.

[0077] Example 2:

[0078] Compared with Example 1, the difference is that in step (1), T1 is 1200°C, t1 is 4h, and other conditions are the same.

[0079] Example 3:

[0080] Compared with Example 1, the difference is that in step (1), T1 is 1800°C, t1 is 2h, and other conditions are the same.

[0081] Example 4:

[0082] Compared with Example 1, the difference is that in step (1), fluorine gas is used instead of freon (with a volume content of 0.5%) in atmosphere A, and other conditions are the same.

[0083] Example 5:

[0084] Compared with Example 1, the difference is that in step (1), chlorine gas is used instead of freon (with a volume content of 1.5%) in atmosphere A, and other conditions are the same.

[0085] Example 6:

[0086] Compared with Example 1, the difference is that in step (1), an equal amount of carbon tetrachloride is used instead of freon in atmosphere A, and other conditions are the same.

[0087] Example 7:

[0088] Compared with Example 1, the difference is that in step (1), oxygen in atmosphere B is replaced by carbon dioxide (with a carbon dioxide content of 25v%), and other conditions are the same.

[0089] Example 8:

[0090] Compared with Example 1, in step (1), T2 is 700°C, t2 is 3h, and other conditions are the same.

[0091] Example 9:

[0092] Compared with Example 1, in step (2), T3 is controlled to be 300-350°C, and other conditions are the same.

[0093] Example 10:

[0094] Compared with Example 1, the difference is that the cooling medium in step (2) is a mixed solution of water and ethanol (volume ratio 1:1), the temperature is -20°C, the liquid-solid ratio in the quenching stage is 10-15 ml / g, the solid-liquid separation and drying after quenching are carried out to obtain the quenched material, and other conditions are the same.

[0095] Example 11:

[0096] Compared with Example 1, the difference is that the cooling medium in step (2) is water, the temperature is 10°C, the liquid-solid ratio in the quenching stage is 15-20 ml / g, the solid-liquid separation and drying after quenching are carried out to obtain the quenched material, and other conditions are the same.

[0097] Example 12:

[0098] Compared with Example 1, the difference is that the asphalt in step (3) is first dissolved in tetrahydrofuran, and other conditions are the same.

[0099] Example 13:

[0100] Compared with Example 1, the difference is that the asphalt in step (3) is replaced by phenolic resin (the amount is 5% of the weight of the product in step 2), and other conditions are the same.

[0101] Example 14:

[0102] Compared with Example 1, the difference is that the asphalt in step (3) is replaced by tar (the amount is 10% of the weight of the product in step 2), and other conditions are the same.

[0103] Example 15:

[0104] Compared with Example 1, the difference is that the asphalt in step (3) is replaced by an equal weight of glucose, and other conditions are the same.

[0105] Comparative Example 1:

[0106] Compared with Example 1, the difference is that the freon gas is not contained in atmosphere A in step (1), and other conditions are the same.

[0107] Comparative Example 2:

[0108] Compared with Example 1, the difference is that the oxygen is not contained in atmosphere B in step (1), and other conditions are the same.

[0109] Comparative Example 3:

[0110] Compared with Example 1, the difference is that the temperature of T1 in step (1) is 1000°C, and other conditions are the same.

[0111] Comparative Example 4:

[0112] Compared with Example 1, step (2) is omitted. That is, after step (1), the furnace is naturally cooled to room temperature, and then step 3 is performed directly, with other conditions remaining the same.

[0113] Comparative Example 5:

[0114] Compared with Example 1, step (3) is omitted, while other conditions remain the same.

[0115] Comparative Example 6:

[0116] Compared to Example 1, the only difference is that in step 1, the first stage of modification is performed in atmosphere B beforehand, followed by the second stage of modification in atmosphere A. The steps of step 1 are as follows:

[0117] A certain amount of degraded graphite was placed in an atmosphere furnace. Under the protection of argon atmosphere, the temperature was raised to T2 = 600°C. The atmosphere was then changed to a mixture of atmosphere B (containing oxygen / argon, volume ratio 2:8) and held at this temperature for 4 hours (marked as t2). Pure argon gas was then introduced, and the temperature was raised to T1 = 1500°C. A mixture of atmosphere A (Freon / argon, volume ratio 1:99) was then introduced and held at this temperature for 3 hours (marked as t1). Subsequent processing steps were then performed, with other operations and parameters the same as in Example 1.

[0118] Comparative Example 7:

[0119] Compared with Example 1, the only difference is that in step 1, a single-stage mixed atmosphere treatment is used. The difference in step 1 is that a certain amount of failed graphite is placed in an atmosphere furnace, heated to T1 = 800°C under argon atmosphere protection, and then atmosphere C (containing 1% Freon, 20% oxygen, and the remainder argon) is introduced. After holding at this temperature for 7 hours, the treatment in step 2 is performed. Other operations and parameters are the same as in Example 1.

[0120] Table 1 compares the charge-discharge performance at room temperature and low temperature between the examples and the comparative examples.

[0121]

[0122] In summary, this invention innovatively treats waste graphite anode material sequentially through two stages of atmosphere A and atmosphere B, followed by rapid cooling in a medium, and finally carbon coating. This improves the material's performance, particularly its low-temperature stability. Furthermore, unexpectedly superior low-temperature performance can be achieved under preferred atmosphere A containing sulfur (Examples 1 / 4-6) and preferred alcohol-water cooling medium.

Claims

1. A method for preparing a spent battery failure graphite-based regenerated graphite material, characterized by, The waste battery failure graphite is pre-processed by a first gas-solid modification in atmosphere A and at temperature T1, and then by a second gas-solid modification in atmosphere B and at temperature T2, to obtain modified material; the atmosphere A comprises a halogen-containing atmosphere, and the temperature T1 is above 1100°C; the atmosphere B is an atmosphere containing at least one functional gas selected from oxygen and carbon dioxide, and the temperature T2 is in the range of 400-800°C; The modified material is subjected to quenching treatment to obtain quenched material; The quenched material is compounded with a carbon source and then subjected to carbonization treatment, to obtain the waste battery failure graphite-based regenerated graphite material.

2. The method for preparing recycled graphite material based on waste battery failure as described in claim 1, characterized in that, The waste battery failure graphite is a graphite-containing material obtained by peeling and separating from the positive electrode and / or the negative electrode of a waste battery.

3. The method for preparing recycled graphite material based on waste battery failure as described in claim 2, characterized in that, The waste battery failure graphite further contains at least one of a binder, a conductive agent, an electrolyte and a current collector.

4. The method for preparing recycled graphite material based on waste battery failure as described in claim 2, characterized in that, The content of graphite in the waste battery failure graphite is above 80wt.%.

5. The method for preparing recycled graphite material based on waste battery failure as described in claim 1, characterized in that, In the atmosphere A, the halogen-containing atmosphere comprises at least one of fluorine, chlorine, freon and carbon tetrachloride.

6. The method for preparing recycled graphite material based on waste battery failure as described in claim 5, characterized in that, In the atmosphere A, the halogen-containing atmosphere further comprises a dilution gas, and the dilution gas comprises at least one of nitrogen and an inert gas.

7. The method for preparing recycled graphite material based on waste battery failure as described in claim 6, characterized in that, In the atmosphere A, the volume content of the halogen-containing atmosphere is in the range of 0.05-2%.

8. The method for preparing recycled graphite material based on waste battery failure as described in claim 1, characterized in that, The temperature T1 is in the range of 1200-1800°C.

9. The method for preparing recycled graphite material based on waste battery failure as described in claim 1, characterized in that, The first gas-solid modification is performed for 2-4h.

10. The method for preparing recycled graphite material based on waste battery failure as described in claim 1, characterized in that, In the atmosphere B, the functional gas further comprises a dilution gas, and the dilution gas comprises at least one of nitrogen and an inert gas.

11. The method for preparing recycled graphite material based on waste battery failure as described in claim 10, characterized in that, In the atmosphere B, the volume content of the functional gas is in the range of 10-30%.

12. The method for preparing recycled graphite material based on waste battery failure as described in claim 1, characterized in that, The holding time at the temperature T2 is in the range of 3-6h.

13. The method for preparing recycled graphite material based on waste battery failure as described in claim 1, characterized in that, The modified material is subjected to quenching treatment while being hot.

14. The method for preparing recycled graphite material based on waste battery failure as described in claim 13, characterized in that, The modified material is subjected to quenching treatment while being hot.

15. The method for preparing recycled graphite material based on waste battery failure as described in claim 13, characterized in that, The cooling medium comprises pure water, a water-alcohol mixed solution or liquid nitrogen.

16. The method for preparing recycled graphite material based on waste battery failure as described in claim 15, characterized in that, The cooling medium is a water-alcohol mixed solution.

17. The method for preparing recycled graphite material based on waste battery failure as described in claim 15, characterized in that, The initial temperature of the pure water is in the range of 0-20°C. The temperature of the water-alcohol mixed solution is in the range of -40-20°C.

18. The method for preparing recycled graphite material based on waste battery failure as described in claim 1, characterized in that, The carbon source comprises at least one of pitch, tar, resin and glucose.

19. The method for preparing recycled graphite material based on waste battery failure as described in claim 18, characterized in that, The weight ratio of the quenched material to the carbon source is in the range of 100:5-12.

20. The method for preparing recycled graphite material based on waste battery failure as described in claim 1, characterized in that, The carbonization process is performed at a temperature in the range of 950-1350°C.

21. The method for preparing recycled graphite material based on waste battery failure as described in claim 1, characterized in that, The carbonization process is performed under negative pressure.

22. The method for preparing recycled graphite material based on waste battery failure as described in claim 1, characterized in that, The carbonization time is in the range of 2-4h.

23. The method for preparing recycled graphite material based on waste battery failure as described in claim 1, characterized in that, The carbonization process is preceded by pre-carbonization treatment.

24. The method for preparing recycled graphite material based on waste battery failure as described in claim 23, characterized in that, The pre-carbonization temperature is in the range of 300-500°C.

25. The method for preparing recycled graphite material based on waste battery failure as described in claim 24, characterized in that, The pre-carbonization time is in the range of 1-3h.

26. A waste battery failure graphite-based regenerated graphite material prepared by the preparation method of any one of claims 1-25.

27. A graphite negative electrode material comprising a negative electrode active material, a binder, and a conductive agent, characterized in that, The negative electrode active material comprises the waste battery failure graphite-based regenerated graphite material prepared by the preparation method of any one of claims 1-25.

28. The graphite negative material of claim 27, wherein, The content of the waste battery failure graphite-based regenerated graphite material in the negative electrode active material is above 50wt.%.

29. The graphite negative material of claim 27 or 28, wherein, The weight ratio of the negative electrode active material, the binder and the conductive agent is in the range of 85-100:1-15:1-15.

30. A battery comprising a negative electrode comprising a current collector and a negative electrode material complexed on a surface thereof, characterized in that, The negative electrode material is the graphite negative electrode material of any one of claims 27-29.

Images