Waste graphite-based repairing and regenerating material for removing heterogeneous carbon as well as preparation method and application of waste graphite-based repairing and regenerating material

Abstract

The invention belongs to the field of waste battery recycling, and particularly discloses a waste graphite-based repairing and regenerating material for removing heterogeneous carbon and preparation and application thereof.The waste graphite is subjected to flotation in a flotation reagent, and graphite concentrate is obtained; wherein the flotation reagent comprises an inhibitor, a collecting agent and a foaming agent, the graphite concentrate is subjected to gravity separation treatment, and graphite gravity separation concentrate is obtained; the method comprises the following steps: carrying out first-stage heat treatment on graphite gravity concentrate in advance under the conditions of protective atmosphere and high temperature T1, then switching the atmosphere into atmosphere a, and carrying out second heat treatment under the condition of low temperature T2 to prepare the waste graphite-based repairing and regenerating material without heterogeneous carbon, wherein the temperature T1 ranges from 900 DEG C to 1200 DEG C; the temperature T2 is 300 to 600 DEG C; the atmosphere a comprises oxygen and auxiliary gas, and the auxiliary gas comprises at least one of alcohol and hydrocarbon. According to the method, the problems of selective separation of graphite and heterogeneous carbon in the waste graphite and the like can be solved, and a high-performance active material can be obtained.

Description

Technical Field

[0001] The present invention belongs to the field of battery material recycling, and specifically relates to the field of waste graphite resource regeneration. Background Art

[0002] Artificial graphite is produced by calcining petroleum coke, needle coke, and pitch at a certain temperature, followed by crushing, grading, and high-temperature graphitization (typically 3000°C). This high-temperature process is supported by fossil fuel and electricity consumption, resulting in significant carbon emissions. Data indicates that the energy consumption and greenhouse gas emissions during the graphitization stage are approximately 13.8 kg CO2-eq / kg and 45.9 MJ / kg, respectively. Currently, the price of battery-grade graphite has reached as high as $8,000-13,000 per ton, accounting for nearly 10% of the total cost of lithium-ion batteries.

[0003] In contrast, waste graphite recovered from spent LIBs already has a high degree of graphitization and only requires purification and reconditioning before it can be reused in LIBs. Furthermore, compared to high-temperature graphitization, this purification and reconditioning process has lower carbon emissions, making recycling waste graphite more cost-effective and sustainable. Furthermore, recycled graphite has significant potential for reuse not only as anodes in lithium-ion batteries but also in supercapacitors, catalysis, and water treatment. Therefore, the purification and regeneration of waste graphite has become a major research direction for anode materials in the future.

[0004] Impurities commonly contained in waste graphite include conductive agents (such as carbon black, carbon nanotubes, etc.), binders (such as sodium carboxymethyl cellulose, styrene-butadiene rubber, polyvinylidene fluoride, polyacrylic acid, etc.), residual electrolyte components (EC DEC), and metal impurities (CuAlFe, etc.). Among them, metal impurities can generally be effectively removed by pickling or high-temperature purification. However, the remaining conductive agents, binders, electrolyte components and other heterogeneous carbon components are mostly adsorbed on the surface of waste graphite particles, and even embedded in graphite sheets and lattices, and are difficult to remove by conventional methods. The presence of heterogeneous carbon will cause the specific surface area of the graphite negative electrode material to be too high, further causing many problems such as low first efficiency, poor high-temperature storage and cycle performance, which limits the application range of waste graphite. Therefore, effectively removing heterogeneous carbon in waste graphite is of great significance for improving the application range of waste graphite and expanding its recycling value.

[0005] However, the existing technology does not have an effective and highly selective separation method for waste graphite materials and highly embedded heterogeneous carbon materials, making it difficult to effectively utilize the performance of recycled materials in terms of initial charge and discharge performance. Summary of the Invention

[0006] In view of the problems that existing waste graphite materials lack effective means for highly selective separation of graphite and heterogeneous carbon, and the performance of the materials is not ideal, the first purpose of the present invention is to innovatively provide a method for preparing waste graphite-based repair and regeneration materials by removing heterogeneous carbon, aiming to highly selectively separate the useless heterogeneous carbon therein, and then obtain a method for regenerated graphite with high performance based on a simple process repair.

[0007] The second purpose of the present invention is to provide a waste graphite-based repair and regeneration material obtained by the preparation method and free of heterogeneous carbon, and its application in lithium-ion batteries.

[0008] The third object of the present invention is to provide a lithium-ion battery comprising the waste graphite-based repair and regeneration material from which heterogeneous carbon has been removed, and its negative electrode and negative electrode material.

[0009] Graphite from used batteries not only contains numerous structural defects and film-forming impurities, but also contains a complex distribution of heterogeneous carbon, making separation difficult using traditional methods such as flotation. Current methods for recycling used graphite primarily focus on optimizing impurities and repairing structural defects, with less consideration given to the impact of heterogeneous carbon on the performance of repair materials. Based on this current situation, the present invention proposes an innovative improvement:

[0010] A method for preparing waste graphite-based repair and regeneration materials by removing heterogeneous carbon comprises flotating waste graphite in a flotation agent to obtain graphite concentrate; wherein the flotation agent comprises an inhibitor, a collector, and a frother, wherein the collector comprises a collector A having a structure of formula 1 and a collector B having a structure of formula 2;

[0011]

[0012] The R1 is C2~C 10 Alkyl or alkoxy substituted alkyl, said R2 is C2~C 10 alkyl, alkoxy substituted alkyl, phenyl or substituted phenyl; wherein M is H, Na, K or NH4;

[0013] The graphite concentrate is subjected to gravity separation treatment to obtain graphite gravity separation concentrate;

[0014] The graphite gravity separation concentrate is pre-heated in a protective atmosphere at a high temperature of temperature T1 for a first stage, and then the atmosphere is switched to atmosphere a and a second heat treatment is performed at a low temperature of temperature T2 to produce a waste graphite-based repair and regeneration material with heterogeneous carbon removed;

[0015] Wherein, the temperature T1 is 900~1200℃; the temperature T2 is 300~600℃;

[0016] Atmosphere a contains oxygen and auxiliary gas, and the auxiliary gas includes at least one of alcohol and hydrocarbon.

[0017] In response to the problems that graphite and heterogeneous carbon in waste graphite are highly interwoven and difficult to effectively separate, which affects its regeneration performance, the present invention innovatively floats the waste graphite under the flotation conditions, and further combines it with subsequent gravity separation and the special variable gas gradient and variable temperature treatment process. This can effectively separate the heterogeneous carbon that is efficiently interwoven in the waste graphite, and can obtain a graphite repair material with excellent initial charge and discharge performance, high temperature performance and rate through high recovery and resource regeneration.

[0018] In the present invention, the waste graphite is a material obtained by stripping the negative electrode of waste batteries.

[0019] In the present invention, the heterogeneous carbon can be the non-graphitizable carbon component in waste graphite. For example, the content of heterogeneous carbon in the waste graphite is 5 to 20 wt.%.

[0020] In the present invention, the combination of flotation-gravity separation and two-stage variable gas gradient heat treatment, further coordinated with the joint control of the conditions of the treatment process, can facilitate efficient synergy and optimize the separation effect of graphite and heterogeneous carbon, thereby facilitating the improvement of the electrochemical properties of the repaired material (such as capacity utilization, high temperature and fast charging performance).

[0021] In the present invention, based on the special combined collector, it can help improve the separation effect of graphite and heterogeneous carbon, and is conducive to regeneration to obtain high-performance recycled materials.

[0022] Preferably, in the collector, the weight ratio of the collector A to the collector B is 1:0.5-2.

[0023] Preferably, the collector further comprises at least one of the collector C of formula 3 and cyclohexane acid soap;

[0024]

[0025] In formula 3, R3 is C8~C 14 Straight chain alkyl or C8~C 14 The linear alkoxy group, wherein M is H, Na, K or NH4. The research also shows that the special combined collector can further facilitate the separation of graphite and heterogeneous carbon, and facilitate the regeneration of high-performance recycled materials.

[0026] Preferably, in the collector, the weight ratio of the collector A to the collector C is 1:1-4.

[0027] Preferably, in the collector, the weight ratio of the collector A to the cyclohexane acid soap is 1:0.5-1.

[0028] Preferably, in the flotation stage, the amount of the collector is 30-80 g / t; further 35-55 g / t.

[0029] In the present invention, the inhibitor may be an inhibitory component known in the industry, for example, at least one of water glass, sodium metaphosphate, sodium thiosulfate, and potassium dichromate.

[0030] In the present invention, the foaming agent may be an inhibitory component known in the industry, for example, an ether alcohol foaming agent, and may further be at least one of methyl ether alcohol, ethyl ether alcohol, and butyl ether alcohol.

[0031] Preferably, in the flotation stage, the dosage of the depressant is 10-20 g / t, and the dosage of the frother is 40-80 g / t.

[0032] Preferably, the gravity separation device is a shaking table gravity separation device or an air flow spiral device.

[0033] In the first stage of heat treatment, the protective atmosphere is at least one of nitrogen and an inert gas.

[0034] In the present invention, the temperature T1 is preferably 1000-1150° C., and more preferably 1100-1150° C. Under the preferred conditions, better regeneration performance can be obtained.

[0035] Preferably, the holding time at temperature T1 is 4 to 6 hours.

[0036] In the present invention, in atmosphere a, the alcohol includes C1-C4 alcohols with a boiling point below 350° C., preferably at least one of methanol, ethanol, and isopropanol.

[0037] Preferably, the hydrocarbon is at least one of alkanes, alkenes and alkynes with a carbon number of 4 or less.

[0038] Preferably, the atmosphere a comprises oxygen, alcohol and hydrocarbons; preferably, the volume ratio of oxygen, alcohol and hydrocarbons is 1-4:1:1-4; further preferably, it can be 2-3:1:1-2.

[0039] Preferably, the atmosphere a further comprises a diluent gas, and the diluent gas is at least one of nitrogen and an inert gas.

[0040] Preferably, the volume content of the diluent in atmosphere a is below 90v%, and can further be 60-90v%, or even 65-75v%. Under the preferred conditions, it can further cooperate with the process to help further improve the high temperature and rate performance of the regenerated material.

[0041] In the present invention, the temperature T2 may be 400-500° C., more preferably 450-500° C. Under the preferred conditions, the temperature T2 can be further coordinated with the process to further improve the high temperature and rate performance of the recycled material.

[0042] Preferably, the holding time at temperature T2 is 4 to 8 hours.

[0043] Preferably, during the temperature T2 holding process, the atmosphere a is used for pressurization, and the system pressure is controlled to be 0.2-1 MPa during the holding period. Research in the present invention has shown that the gradient gas change technology, combined with the combined pressure control, can achieve synergy, further improving the separation of heterogeneous carbon and graphite, and further improving the performance of the regenerated material.

[0044] The present invention also provides a waste graphite-based repair and regeneration material obtained by the preparation method and having heterogeneous carbon removed.

[0045] The preparation method of the present invention can give the prepared material special physical and chemical characteristics, and the material prepared by the preparation method can also take into account excellent electrochemical performance.

[0046] The present invention also provides the use of the waste graphite-based repair and regeneration material obtained by the preparation method and having heterogeneous carbon removed, which is used as a negative electrode active material for preparing lithium-ion batteries.

[0047] In the present invention, the material can be used as a negative electrode active material based on known processes, and the required lithium ion battery and its negative electrode and negative electrode material can be prepared based on known means.

[0048] The present invention also provides a negative electrode of a lithium ion battery, which comprises the waste graphite-based repair and regeneration material obtained by the preparation method and from which heterogeneous carbon is removed.

[0049] The present invention also provides a lithium-ion battery comprising the negative electrode of the waste graphite-based repair and regeneration material containing the heterogeneous carbon removed according to the present invention.

[0050] Beneficial effects

[0051] The present invention focuses on the problem of separating graphite and heterogeneous carbon in waste graphite, and innovatively proposes a combination of flotation-gravity separation-gas change and cooling gradient heat treatment, and further combines flotation-gravity separation and heat treatment processes and parameters. In this way, synergy can be achieved, and problems such as the selective separation of graphite and heterogeneous carbon in waste graphite can be improved. Active materials with high performance, such as high capacity, rate and high-temperature stability, can be obtained efficiently and with high recovery rate.

[0052] The present invention also shows that the combined control of the composition of the collector, the gradient gas atmosphere and the pressure in the flotation process can help further improve the separation selectivity of graphite and unfavorable heterogeneous carbon, and can also help improve the high capacity, rate and high temperature stability of the recycled material. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 This is the SEM image of the graphite material repaired in Example 1.

[0054] Figure 2 This is the XRD pattern of the graphite material repaired in Example 1.

[0055] Figure 3 This is the first charge and discharge curve of the graphite material repaired in Example 1.

[0056] Figure 4 AC impedance diagram of waste graphite before recycling with different repair methods.

[0057] Figure 5 60°C high-temperature storage performance diagram of the repair materials obtained in Example 1 and Comparative Example 1;

[0058] Figure 6 The figure shows the room temperature rate charge and discharge performance of waste graphite with different repair methods. DETAILED DESCRIPTION

[0059] The selected waste graphite is a material obtained by stripping the negative electrode of waste batteries, wherein the graphite content is 88±0.2% and the heterogeneous carbon content is 10±0.1%.

[0060] Example 1:

[0061] 1) Flotation:

[0062] Mix the waste graphite with the flotation agent for 10 minutes, place it in a flotation machine for flotation, and obtain the flotation material;

[0063] Inhibitor: water glass, dosage is 10g / t;

[0064] Collector: Collector A (Formula 1A: )10g / t; Collector B (Formula 2A )10g / t; Collector C (Formula 3A; ), 20g / t;

[0065] Foaming agent: methyl ether alcohol 50g / t;

[0066] 2) Re-election:

[0067] Use airflow spiral equipment for gravity separation;

[0068] 3) Gas treatment:

[0069] Step 2) The material is introduced into a roller kiln with nitrogen, and the temperature is raised to T1 (1000°C) for reaction for 5 hours; then the temperature is lowered to temperature T2 (400°C), and the atmosphere is changed to atmosphere a (wherein oxygen is 10% by volume, methanol is 5% by volume, methane is 5% by volume, and the remaining gas is nitrogen). After being kept at this temperature for 6 hours, the material is cooled and discharged. During the holding period at temperature T2, the pressure in the heat treatment furnace is controlled to be 0.2 MPa.

[0070] 4) Sieving: The material in step 3) is sieved through a 250-mesh sieve to obtain waste graphite repair and regeneration material (regenerated graphite);

[0071] The composition of the waste graphite repair and regeneration material is shown in Table 1:

[0072] Table 1 Component analysis

[0073]

[0074] From the composition analysis of the waste graphite repair and regeneration materials, it can be seen that the material has a high fixed carbon content and few impurities.

[0075] SEM images of waste graphite repair and recycling materials Figure 1 .

[0076] XRD pattern of waste graphite repair and recycling materials is shown in Figure 2 It can be seen that the (002) crystal plane diffraction peak intensity of the repaired graphite material is high, and there are no other obvious impurity peaks.

[0077] The first charge and discharge curve of waste graphite repair and recycling materials is shown in Figure 3 .

[0078] Example 2:

[0079] Compared with Example 1, the only difference is that the collector in the flotation reagent in step 1 is changed. The experimental groups are:

[0080] Group A: The collector includes collector A and collector B in a weight ratio of 1:1, and the total amount of the collector is the same as that in Example 1;

[0081] Group B: Collectors include Collector A, Collector B, Collector C, and Collector D (naphthenic acid soap) in a weight ratio of 1:1:1:1; and the total amount of the collectors is the same as in Example 1;

[0082] Other operations and parameters are the same as in Example 1.

[0083] Example 3:

[0084] The only differences compared to Example 1 are that in step 1, the total amount of collector used is 50 g / t, the amount of inhibitor used is 15 g / t, the amount of frother used is 55 g / t, and in step 2, the gravity separation is carried out using a shaking table gravity separation device. Other operations and parameters are the same as in Example 1.

[0085] Example 4:

[0086] Compared with Example 1, the only difference is that in step 3, the components in atmosphere a are changed. The experimental groups are:

[0087] Group A: atmosphere a, containing 10v% oxygen, 10v% methanol; the remaining gas is nitrogen;

[0088] Group B: atmosphere a, containing 10v% oxygen, 10v% methane; the remaining gas is nitrogen;

[0089] Group C: Atmosphere a contains 15v% oxygen, 5v% methanol, and 10v% methane; the remaining gas is nitrogen.

[0090] Other operations and parameters are the same as in Example 1.

[0091] Example 5:

[0092] Compared with Example 1, the only difference is that in step 4, the gas change treatment process in step 3 is changed. The experimental group is:

[0093] Group A: Temperature T1 is 1150°C, and the holding time at this temperature is 4 hours; Temperature T2 is 500°C, and the holding time at this temperature is 5 hours. During the holding stage at temperature T2, the system is pressurized using atmosphere a at a pressure of 0.3 MPa;

[0094] Group B: During the temperature T2 holding process, the pressure in the treatment stage was controlled to be atmospheric pressure (0.1-0.15 MPa).

[0095] Other operations and parameters are the same as in Example 1.

[0096] Comparative Example 1:

[0097] Compared with Example 1, the only difference is that the flotation in step 1 is not performed, and the waste graphite is directly subjected to step 2 and subsequent treatments. Other operations and parameters are the same as those in Example 1.

[0098] Comparative Example 2:

[0099] Compared with Example 1, the only difference is that in step 1, the collector is changed. The experimental groups are:

[0100] Group A: The collector is oleic acid;

[0101] Group B: The collector is a single Formula 1A;

[0102] Group C: The collector is a single formula 1B;

[0103] The amount of collector used and other operations and parameters are the same as in Example 1.

[0104] Comparative Example 3:

[0105] Compared with Example 1, the only difference is that step 2 is not performed, and the flotation concentrate of step 1 is directly subjected to step 3 and subsequent treatments. Other operations and parameters are the same as those of Example 1.

[0106] Comparative Example 4:

[0107] Compared with Example 1, the only difference is that the waste graphite is first processed in step 2, then processed in step 1, and then processed in step 3. Other operations and parameters are the same as in Example 1.

[0108] Comparative Example 5:

[0109] Compared with Example 1, the only difference is that the conditions of step 3 are changed. The experimental groups are:

[0110] Group A: No gradient temperature treatment was performed, that is, T1 was set to 400°C; other operations and parameters were the same as in Example 1;

[0111] Group B: The atmosphere was an oxygen-nitrogen mixture containing 20v% oxygen;

[0112] Other operations and parameters are the same as in Example 1.

[0113] Button battery assembly:

[0114] A graphite electrode made from waste repaired and recycled graphite as the active material was used as the working electrode (the weight ratio of active material, PVDF, and carbon black was 9:1:1), a metal lithium sheet was used as the counter electrode, a Celgard 2400 porous diaphragm was used as the diaphragm, and the electrolyte was a 1MLiPF6 DMC:EC solution (volume ratio of 1:1), assembled into a CR2025 button cell. Electrochemical testing was conducted in the Wuhan Blue Electric Battery Comprehensive Testing System. The entire test was conducted in a constant temperature chamber. Each charge and discharge cycle was allowed to rest for 10-30 minutes to eliminate polarization effects. Before testing, a complete charge and discharge cycle was performed at a current of 0.1C, and the initial discharge capacity was recorded. The test voltage range was 0.001-2.5V. In addition, the rate was tested at 4C / 0.1C.

[0115] Battery cell assembly:

[0116] A soft-pack cell was designed using a graphite electrode made from recycled graphite as the negative electrode (the ratio of graphite active material, conductive carbon black SP, binder PVDF, and thickener CMC was 93:2.5:2.5:2). The positive electrode was LFP (LFP, conductive carbon black SP, and binder PVDF in a ratio of 93:4:3). L40 electrolyte was used. High-temperature cycling stability was measured by cycling the cell for 200 cycles at 60°C and 0.1C.

[0117] Table 1:

[0118]

[0119] It can be seen from Example 1 and the comparative example that an innovative combination of flotation-gravity separation-gas change and cooling gradient heat treatment is proposed, and further combined with the flotation-gravity separation and heat treatment processes and parameters, so as to achieve synergy, improve the problems of graphite and heterogeneous carbon selective separation in waste graphite, and obtain high-performance active materials with high efficiency and high recovery rate.

[0120] It can be seen from Examples 1 and 2 to 5 that the combined control of the composition of the collector, the gradient gas atmosphere, and the pressure during the flotation process can help further improve the separation selectivity of graphite and unfavorable heterogeneous carbon, and help improve the performance of the recycled material.

[0121] The AC impedance diagrams of the waste graphite repair and regeneration materials of Example 1 and Comparative Example 1 are shown in Figure 4 It can be seen that after special repair, the charge transfer impedance in the waste graphite is reduced and the diffusion impedance of lithium ions is reduced, indicating that lithium ions are easier to diffuse in the graphite after repair in this case.

[0122] In addition, the high temperature storage test conditions are as follows: the battery cell is stored in a high temperature environment of 60℃ for 7 days, and then discharged directly at 1C. The retention rate is calculated by calculating the ratio of the remaining discharge capacity to the initial capacity; at the same time, the battery cell after 1C discharge is fully charged and discharged again at 1C, and the recovery rate is calculated by calculating the ratio of the discharge capacity to the initial capacity. The rate charge and discharge test conditions are to test the charge and discharge efficiency at 0.8C, 1C, 1.2C, and 1.4C at room temperature. Test structure see Figure 5 and Figure 6 It can be seen that the high-temperature storage performance of waste graphite after special repair is better, and the rate charge and discharge performance is significantly improved compared with the existing common repair method.

Claims

1. A method for preparing waste graphite-based repair and regeneration materials by removing heterogeneous carbon, characterized in that: flotation of waste graphite in a flotation agent to obtain graphite concentrate; wherein the flotation agent comprises an inhibitor, a collector and a frother, wherein the collector comprises a collector A having a structure of formula 1 and a collector B having a structure of formula 2; The R1 is C2~C 10 Alkyl or alkoxy substituted alkyl, said R2 is C2~C 10 alkyl, alkoxy substituted alkyl, phenyl or substituted phenyl; wherein M is H, Na, K or NH4; The graphite concentrate is subjected to gravity separation treatment to obtain graphite gravity separation concentrate; The graphite gravity separation concentrate is pre-heated in a protective atmosphere at a high temperature of temperature T1 for a first stage, and then the atmosphere is switched to atmosphere a and a second heat treatment is performed at a low temperature of temperature T2 to produce a waste graphite-based repair and regeneration material with heterogeneous carbon removed; Wherein, the temperature T1 is 900~1200℃; the temperature T2 is 300~600℃; Atmosphere a contains oxygen and auxiliary gas, and the auxiliary gas includes at least one of alcohol and hydrocarbon.

2. The method for preparing waste graphite-based repair and regeneration materials with heterogeneous carbon removed according to claim 1, wherein: The waste graphite is obtained by stripping the negative electrode of waste batteries; Preferably, the content of graphite in the waste graphite is 80 to 95 wt.%; the content of heterogeneous carbon is 5 to 20 wt.%.

3. The method for preparing waste graphite-based repair and regeneration materials with heterogeneous carbon removed according to claim 1, wherein: In the collector, the weight ratio of the collector A to the collector B is 1:0.5-2; Preferably, the collector further comprises at least one of the collector C of formula 3 and cyclohexane acid soap; The R3 is C8~C 14 Straight chain alkyl or C8~C 14 Straight chain alkoxy; Preferably, in the collector, the weight ratio of the collector A to the collector C is 1:1 to 4; Preferably, in the collector, the weight ratio of the collector A to the cyclohexane acid soap is 1:0.5-1; Preferably, in the flotation stage, the amount of the collector is 30 to 80 g / t; further 35 to 55 g / t; Preferably, the inhibitor comprises at least one of water glass, sodium metaphosphate, sodium thiosulfate, and potassium dichromate; Preferably, the foaming agent is an ether alcohol foaming agent, specifically at least one of methyl ether alcohol, ethyl ether alcohol, and butyl ether alcohol; Preferably, in the flotation stage, the dosage of the depressant is 10-20 g / t, and the dosage of the frother is 40-80 g / t.

4. The method for preparing waste graphite-based repair and regeneration materials with heterogeneous carbon removed according to claim 1, wherein: The gravity separation equipment is a shaking table gravity separation equipment or an air flow spiral equipment.

5. The method for preparing waste graphite-based repair and regeneration materials with heterogeneous carbon removed according to claim 1, wherein: In the first heat treatment, the protective atmosphere is at least one of nitrogen and an inert gas; Preferably, the holding time at temperature T1 is 4 to 6 hours.

6. The method for preparing waste graphite-based repair and regeneration materials with heterogeneous carbon removed according to claim 1, wherein: In atmosphere a, the alcohol includes C1-C4 alcohols with a boiling point below 350°C, preferably at least one of methanol, ethanol, and isopropanol; Preferably, the hydrocarbon is at least one of alkanes, alkenes, and alkynes having a carbon number of 4 or less; Preferably, the atmosphere a comprises oxygen, alcohol and hydrocarbons; preferably, the volume ratio of oxygen, alcohol and hydrocarbons is 1-4:1:1-4; Preferably, the atmosphere a further comprises a diluent gas, wherein the diluent gas is at least one of nitrogen and an inert gas; Preferably, in atmosphere a, the volume content of the diluent gas is below 90v%; Preferably, the holding time at temperature T2 is 4 to 8 hours; Preferably, during the insulation process at temperature T2, the atmosphere a is used for pressurization, and the pressure of the system is controlled to be 0.2-1 MPa during the insulation period.

7. A waste graphite-based repair and regeneration material with heterogeneous carbon removed, obtained by the preparation method according to any one of claims 1 to 6.

8. An application of waste graphite-based repair and regeneration materials obtained by the preparation method according to any one of claims 1 to 6, wherein the waste graphite-based repair and regeneration materials are free of heterogeneous carbon. It is used as negative electrode active material to prepare lithium-ion batteries.

9. A negative electrode of a lithium ion battery, characterized in that: The invention relates to a waste graphite-based repair and regeneration material with heterogeneous carbon removed, which is prepared by the preparation method according to any one of claims 1 to 6.

10. A lithium ion battery, characterized in that: The negative electrode according to claim 9 is included.

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