Method for recycling graphite negative electrode material

Abstract

In order to overcome the problems of low recycling rate of waste graphite negative electrode and environmental pollution caused by waste PVC burning in the prior art, the present application provides a method for recycling and reusing graphite negative electrode material, wherein the waste graphite negative electrode powder is blended and coated with polyvinyl chloride and recovery aids such as conductive and heat-conductive carbon materials; the coated waste graphite negative electrode powder is heat treated; the waste graphite negative electrode powder is washed and metal ion leaching; the leaching solution is impurity-removed and lithium carbonate is recovered; and the waste graphite is heat treated for recycling. The method for recycling and reusing graphite negative electrode material provided by the present application uses polyvinyl chloride and heat-conductive carbon materials as recovery aids, which is beneficial to enhancing the thermal conductivity of the mixed material, avoiding long-time high-temperature calcination of waste graphite, reducing graphite loss, realizing rapid recovery of lithium element, and shortening the recycling period and improving the effect. Meanwhile, the use of acid is reduced, and the production and economic benefits are high.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery material recycling technology, specifically relating to a method for recycling and reusing graphite anode materials. Background Technology

[0002] Currently, waste batteries are generally dismantled and then sorted for recycling. Because the added value of graphite, the negative electrode material, is low, most waste graphite negative electrode materials are disposed of through landfilling and incineration, resulting in resource waste. Current purification technologies for waste graphite negative electrodes are broadly categorized into high-temperature calcination, acid leaching, and electrochemical methods. High-temperature calcination produces toxic gases, requires high temperatures, consumes a lot of energy, and increases recycling costs. Furthermore, at higher temperatures, many oxygen-containing functional groups are generated on the graphite surface; as the temperature increases, the graphite loss rate and surface roughness also increase, exacerbating graphite loss. Acid leaching typically involves first separating copper foil and waste graphite using calcination, then removing metallic impurities from the waste graphite using inorganic acid leaching. This method can recover valuable metals efficiently and completely, but the waste liquid generated by acid leaching causes environmental pollution. Electrochemical methods can only separate the current collector copper foil from the graphite active material; the problem of recovering valuable metals remains unresolved. Existing patent literature attempts to use chlorine gas at 1000-1100℃ to convert high-boiling-point metals and oxides into low-boiling-point chlorides, thereby reducing the reaction temperature and saving energy. However, the chlorides produced by the reaction are toxic and can corrode equipment.

[0003] PVC and similar materials have advantages such as light weight, waterproofing, moisture resistance, flame retardancy, and heat insulation, making them widely used. However, in the treatment of waste plastics, especially chlorinated plastics, incineration releases large amounts of HCl gas and chlorine-toxic pollutants due to the high chlorine content (over 50%) in PVC, causing environmental damage. Currently, many plastic wastes are treated similarly to other solid wastes, primarily through landfill and incineration. Waste plastics that are not properly treated in a timely manner will produce acidic and alkaline organic matter during landfill accumulation, and in severe cases, heavy metals may dissolve from the waste. Thermal degradation is a pyrolysis technology. Under certain conditions or with catalysis, in an anaerobic or oxygen-deficient environment, substances are heated to 350–900°C and converted into gas, coke, and water. The HCl produced by pyrolysis catalyzes the thermal degradation reaction.

[0004] Waste lithium-ion battery anode materials contain not only copper and graphite, but also a high content of lithium, typically around 31 mg / g. Lithium in waste graphite exists primarily in the forms of Li₂CO₃, Li₂O, LiF, ROCO₂Li, and CH₃OLi, and can be classified into water-soluble and water-insoluble lithium salts. Some components can be directly leached in deionized water, while others are embedded in the graphite layers and require acid reaction to recover lithium from between the graphite layers. After a single water washing step, the metal ion content in the graphite anode is 0.1%–2%, and the ash content by weight is 1%–5%. Summary of the Invention

[0005] The technical problem to be solved by this invention is to address the low recycling rate of waste graphite anodes and the environmental pollution caused by the incineration of waste PVC in the prior art. This invention provides a method for recycling and reusing graphite anode materials that have high economic value and are energy-saving and environmentally friendly.

[0006] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0007] A method for recycling and reusing graphite anode materials is provided, comprising the following steps:

[0008] Waste graphite negative electrode powder is fused and coated with PVC powder and conductive and thermally conductive carbon materials;

[0009] The heat treatment of the coated waste graphite negative electrode powder allows the metal elements in the waste graphite negative electrode powder to react with the chlorine elements generated by the thermal decomposition of PVC to obtain metal chloride salts.

[0010] Washing and leaching of waste graphite negative electrode powder with metal chloride salts;

[0011] Heat treatment for recycling waste graphite anode powder.

[0012] Optionally, before performing the "fusion coating of waste graphite negative electrode powder with PVC powder and conductive and thermally conductive carbon material", the waste graphite negative electrode powder is heat-treated in a protective gas at a temperature of 150℃ to 350℃ for a time of 0.5h to 3h.

[0013] Optionally, the protective gas is one or more of Ar, N2, and Kr.

[0014] Optionally, the conductive and thermally conductive carbon material is one or more of carbon nanotubes (CNTs) or graphene (GPE).

[0015] Optionally, the mass percentage of conductive and thermally conductive carbon material in the coated waste graphite negative electrode powder is 0.5 to 5 wt%.

[0016] Optionally, the PVC powder in the coated waste graphite anode powder has a mass ratio of 0.5 to 10 wt%, and the particle size of the PVC powder is ≤1 μm.

[0017] Optionally, the heating rate in the heat treatment of the coated waste graphite negative electrode powder is 2-5℃ / min, the heat treatment temperature is 100-220℃, and the heat treatment time is 20-120min.

[0018] Optionally, a purification agent is added to the washing liquid of the waste graphite negative electrode powder to remove trace amounts of copper element impurities, and a lithium-ion precipitant is added to the washing liquid after purification to enrich alkali metal elements.

[0019] Optionally, the impurity removal agent is one or more of Na2S, K2S, NaHS, H2S, and BaS.

[0020] Optionally, the precipitant is one or more of CO2, Na2CO3, K2CO3, and NaHCO3.

[0021] The graphite anode material recycling method provided by this invention utilizes the chlorine element generated from the initial thermal degradation of polyvinyl chloride (PVC) plastic to fuse and coat heat-treated graphite with conductive and thermally conductive carbon material. The excellent thermal conductivity of the conductive carbon material prevents heat accumulation in the mixture under thermal conditions. The lithium and other metal elements in the waste graphite anode react uniformly with the chlorine element generated from the thermal degradation of PVC, converting metal and metal salt impurities in the waste graphite into easily soluble and soluble salts. After water washing, leaching, and impurity removal, lithium carbonate is obtained. Simultaneously, the graphite undergoes a short-term heat treatment to restore its layered structure. This graphite anode material recycling method provides rapid and effective lithium recovery, while reducing acid usage, wastewater generation, and treatment costs. Using conductive and thermally conductive carbon material as a recycling aid avoids prolonged heat treatment of waste graphite, reducing graphite loss and energy consumption, and shortening the recycling cycle, resulting in better production and economic benefits. Attached Figure Description

[0022] Figure 1 This is a charge-discharge curve of a semi-button battery prepared in Example 1 of the present invention;

[0023] Figure 2 This is a flowchart of the recycling and reuse process for graphite anode materials provided by the present invention. Detailed Implementation

[0024] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0025] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0026] A method for recycling and reusing graphite anode materials is provided, comprising the following steps:

[0027] Waste graphite negative electrode powder is fused and coated with PVC powder and conductive and thermally conductive carbon materials;

[0028] The heat treatment of the coated waste graphite negative electrode powder allows the metal elements in the waste graphite negative electrode powder to react with the chlorine elements generated by the thermal decomposition of PVC to obtain metal chloride salts.

[0029] Washing and leaching of waste graphite negative electrode powder with metal chloride salts;

[0030] Heat treatment for recycling waste graphite anode powder.

[0031] Specifically, the chlorine element generated from the pyrolysis of polyvinyl chloride is fused with and coated with heat-treated graphite and doped with conductive and thermally conductive carbon materials, so that the mixture will not generate heat energy accumulation in a thermal environment. The lithium and other metal elements in the waste graphite negative electrode react uniformly with the chlorine element generated from the thermal degradation of polyvinyl chloride, converting the metal and metal salt impurities in the waste graphite into easily soluble and soluble salts. After water washing and leaching, impurities are removed and precipitation is obtained to obtain lithium carbonate. At the same time, the graphite is subjected to short-term heat treatment to restore its layered structure.

[0032] In this embodiment of the invention, before the "coating of waste graphite negative electrode powder with PVC powder and conductive and thermally conductive carbon material", the waste graphite negative electrode powder is subjected to heat treatment. The heat treatment temperature is 150℃~350℃ and the heat treatment time is 0.5h~3h.

[0033] The heat treatment temperature is 300℃ and the heat treatment time is 1 hour.

[0034] In this embodiment of the invention, the protective gas is one or more of Ar, N2, and Kr.

[0035] The protective gas introduced during the heat treatment is Ar.

[0036] In this embodiment of the invention, the conductive and thermally conductive carbon material is one or more of carbon nanotubes (CNTs) or graphene (GPE).

[0037] The carbon nanotubes (CNTs) are hollow tubes, exhibiting excellent thermal conductivity as a heat transfer material. Adding CNTs to the composite material can effectively improve its thermal conductivity. The graphene GPE is a type of composite material... 2 A new material with hybridized carbon atoms tightly packed into a single-layer two-dimensional honeycomb lattice structure exhibits excellent electrical and optical properties.

[0038] In this embodiment of the invention, the mass percentage of conductive and thermally conductive carbon material in the coated waste graphite negative electrode powder is 0.5-5 wt%.

[0039] In this embodiment of the invention, the mass percentage of PVC ultrafine powder in the coated waste graphite negative electrode powder is 0.5-10 wt%, and the particle size range of the PVC ultrafine powder is ≤1 μm.

[0040] The small particles in the PVC ultrafine powder can fully fill the surface and gaps of the waste graphite anode powder, making the coating more dense and helping the lithium and other metal elements in the waste graphite anode powder to fully react with the chlorine elements produced by the thermal degradation of polyvinyl chloride under heating conditions.

[0041] In this embodiment of the invention, the heating rate of the coated waste graphite negative electrode powder during heat treatment is 2-5℃ / min, the heat treatment temperature is 100-220℃, and the heat treatment time is 20-120min.

[0042] In this embodiment of the invention, a purification agent is added to the washing liquid of the waste graphite negative electrode powder to remove trace amounts of copper element impurities, and a lithium ion precipitant is added to the washing liquid after purification to enrich alkali metal elements.

[0043] In this embodiment of the invention, the impurity removal agent is one or more of Na2S, K2S, NaHS, H2S, and BaS.

[0044] The impurity remover is Na2S, which can remove trace amounts of copper impurities from metal-rich leaching solutions.

[0045] In this embodiment of the invention, the precipitant is one or more of CO2, Na2CO3, K2CO3, and NaHCO3.

[0046] Specifically, the precipitant is Na2CO3, which enriches lithium to obtain lithium carbonate.

[0047] The present invention will be further illustrated by the following examples.

[0048] Example 1

[0049] This embodiment illustrates a method for recycling and reusing graphite anode materials disclosed in this invention, including the following steps:

[0050] Waste graphite anode powder is obtained by discharging and breaking down used batteries.

[0051] The waste lithium battery was discharged in a 1.5 mol / sodium chloride aqueous solution. When the battery voltage dropped below 1.5V, the discharged battery was disassembled to obtain the negative electrode sheet. A certain mass of the negative electrode sheet was cut into pieces and placed in a ceramic crucible and then loaded into a box-type resistance furnace. Ar gas was introduced, and the furnace temperature was raised to 300℃ at a heating rate of 3℃ / min at room temperature and held for 1 hour. Then air was introduced and the temperature was held for 0.5 hours. The negative electrode sheet after high-temperature heat treatment was sieved through a 20-mesh sieve. The material on the sieve was copper current collector, and the material under the sieve was waste graphite negative electrode material (S-Gra).

[0052] Coating of waste graphite anode powder and ultrafine powder:

[0053] The PVC plastic was milled into ultrafine powder with a particle size of 0.1 μm using an air jet mill. A certain amount of PVC ultrafine powder, CNTs and GPE were weighed and mixed with waste graphite negative electrode powder. The mixing speed was 2500 rpm / min and the mixing time was 15 min. The mass percentage of PVC ultrafine powder was 5 wt%, the mass percentage of CNTs was 1.5 wt%, and the mass percentage of GPE was 1.5 wt%, thus obtaining S-Gra@PVC+CNTs / GPE mixed powder.

[0054] Heat treatment of coated waste graphite powder:

[0055] The S-Gra@PVC+CNTs / GPE mixed powder was placed in a tetrafluoroethylene can, N2 gas was introduced, and the can was heated in a sealed manner. The furnace temperature was raised to 180°C at a heating rate of 3°C / min at room temperature and held for 0.5 hours. After cooling to room temperature, the powder was removed.

[0056] Washing and metal ion leaching of waste graphite powder:

[0057] After the waste graphite powder to be heat-treated cools to room temperature, it is removed and deionized water is added at a solid-liquid ratio of 1:15 (g / mL). The mixture is mechanically stirred at room temperature at a stirring speed of 250 rpm / min for 20 min, and then filtered to obtain the first metal-rich washing solution. Then, deionized water is added to the filter residue at a solid-liquid ratio of 1:10 (g / mL). The mixture is mechanically stirred at room temperature at a stirring speed of 250 rpm / min for 10 min, and then filtered to obtain the second metal-rich washing solution. Finally, deionized water is added to the filter residue at a solid-liquid ratio of 1:5 (g / mL). The mixture is stirred at room temperature at a stirring speed of 250 rpm / min for 10 min, and then filtered to obtain the third metal-rich washing solution.

[0058] Leachate impurity removal and lithium carbonate recovery:

[0059] The three washing solutions were enriched, and a certain amount of Na2S was added to them while stirring continuously until all the metal impurity ions were converted into precipitates. After removing the precipitated impurities, the pH value of the solution was adjusted, and Na2CO3 was passed into the solution at room temperature while stirring. The solution was heated in a 90°C water bath for 0.5 hours and then filtered while hot to obtain Li2CO3.

[0060] Heat treatment for recycling waste graphite powder:

[0061] The S-Gra filter residue is dried at 100℃ for 3 hours. The dried waste graphite S-Gra is then placed in a ceramic crucible and loaded into a box-type resistance furnace. Ar protective gas is introduced throughout the process, the heating rate is 5℃ / min, the sintering temperature is 800℃, the holding time is 0.5 hours, and after cooling to room temperature, reusable graphite P-Gra is obtained.

[0062] Example 2

[0063] This embodiment illustrates a method for recycling and reusing graphite anode materials disclosed in this invention, including the following steps:

[0064] Waste graphite anode powder is obtained by discharging and breaking down used batteries.

[0065] The waste lithium battery was discharged in a 1.5 mol / sodium chloride aqueous solution. When the battery voltage dropped below 1.5V, the discharged battery was disassembled to obtain a negative electrode sheet. A certain mass of the negative electrode sheet was cut into pieces and placed in a ceramic crucible and then loaded into a box-type resistance furnace. Ar gas was introduced, and the furnace temperature was raised to 300℃ at a heating rate of 3℃ / min at room temperature and held for 1 hour. Then air was introduced and the temperature was held for 0.5 hours. The negative electrode sheet after high-temperature heat treatment was sieved through a 20-mesh sieve. The material on the sieve was copper current collector, and the material under the sieve was waste graphite negative electrode material.

[0066] Coating of waste graphite anode powder and ultrafine powder:

[0067] The PVC plastic was milled into ultrafine powder with a particle size of 0.1 μm using an air jet mill. A certain amount of PVC ultrafine powder and CNTs were weighed and mixed with waste graphite negative electrode powder. The mixing speed was 2500 rpm / min and the mixing time was 15 min. The mass percentage of PVC ultrafine powder was 5 wt% and the mass percentage of CNTs was 3 wt%, resulting in S-Gra@PVC+CNTs mixed powder.

[0068] Heat treatment of coated waste graphite powder:

[0069] The S-Gra@PVC+CNTs mixed powder was placed in a tetrafluoroethylene can, N2 gas was introduced, and the can was heated in a sealed manner. The furnace temperature was raised to 180°C at a heating rate of 3°C / min at room temperature and held for 0.5 hours. After cooling to room temperature, the powder was removed.

[0070] Washing and metal ion leaching of waste graphite powder:

[0071] After the waste graphite powder to be heat-treated cools to room temperature, it is removed and deionized water is added at a solid-liquid ratio of 1:15 (g / mL). The mixture is mechanically stirred at room temperature at a stirring speed of 250 rpm / min for 20 min, and then filtered to obtain the first metal-rich washing solution. Then, deionized water is added to the filter residue at a solid-liquid ratio of 1:10 (g / mL). The mixture is mechanically stirred at room temperature at a stirring speed of 250 rpm / min for 10 min, and then filtered to obtain the second metal-rich washing solution. Finally, deionized water is added to the filter residue at a solid-liquid ratio of 1:5 (g / mL). The mixture is stirred at room temperature at a stirring speed of 250 rpm / min for 10 min, and then filtered to obtain the third metal-rich washing solution.

[0072] Leachate impurity removal and lithium carbonate recovery:

[0073] The three washing solutions were enriched, and a certain amount of Na2S was added to them while stirring continuously until all the metal impurity ions were converted into precipitates. After removing the precipitated impurities, the pH value of the solution was adjusted, and Na2CO3 was passed into the solution at room temperature while stirring. The solution was heated in a 90°C water bath for 0.5 hours and then filtered while hot to obtain Li2CO3.

[0074] Heat treatment for recycling waste graphite powder:

[0075] The S-Gra filter residue is dried at 100℃ for 3 hours. The dried waste graphite S-Gra is then placed in a ceramic crucible and loaded into a box-type resistance furnace. Ar protective gas is introduced throughout the process, the heating rate is 5℃ / min, the sintering temperature is 800℃, the holding time is 0.5 hours, and after cooling to room temperature, reusable graphite P-Gra is obtained.

[0076] Example 3

[0077] This embodiment illustrates a method for recycling and reusing graphite anode materials disclosed in this invention, including the following steps:

[0078] Waste graphite anode powder is obtained by discharging and breaking down used batteries.

[0079] The waste lithium battery was discharged in a 1.5 mol / sodium chloride aqueous solution. When the battery voltage dropped below 1.5V, the discharged battery was disassembled to obtain a negative electrode sheet. A certain mass of the negative electrode sheet was cut into pieces and placed in a ceramic crucible and then loaded into a box-type resistance furnace. Ar gas was introduced, and the furnace temperature was raised to 300℃ at a heating rate of 3℃ / min at room temperature and held for 1 hour. Then air was introduced and the temperature was held for 0.5 hours. The negative electrode sheet after high-temperature heat treatment was sieved through a 20-mesh sieve. The material on the sieve was copper current collector, and the material under the sieve was waste graphite negative electrode material.

[0080] Coating of waste graphite anode powder and ultrafine powder:

[0081] The PVC plastic was milled into ultrafine powder with a particle size of 0.1 μm using an air jet mill. A certain amount of PVC ultrafine powder and GPE were weighed and mixed with waste graphite negative electrode powder. The mixing speed was 2500 rpm / min and the mixing time was 15 min. The mass percentage of PVC ultrafine powder was 5 wt% and the mass percentage of GPE was 3 wt%, thus obtaining S-Gra@PVC+GPE mixed powder.

[0082] Heat treatment of coated waste graphite powder:

[0083] The S-Gra@PVC+GPE mixed powder was placed in a tetrafluoroethylene can, N2 gas was introduced, and the can was heated in a sealed manner. The furnace temperature was raised to 180°C at a heating rate of 3°C / min at room temperature and held for 0.5 hours. After cooling to room temperature, the powder was removed.

[0084] Washing and metal ion leaching of waste graphite powder:

[0085] After the waste graphite powder to be heat-treated cools to room temperature, it is removed and deionized water is added at a solid-liquid ratio of 1:15 (g / mL). The mixture is mechanically stirred at room temperature at a stirring speed of 250 rpm / min for 20 min, and then filtered to obtain the first metal-rich washing solution. Then, deionized water is added to the filter residue at a solid-liquid ratio of 1:10 (g / mL). The mixture is mechanically stirred at room temperature at a stirring speed of 250 rpm / min for 10 min, and then filtered to obtain the second metal-rich washing solution. Finally, deionized water is added to the filter residue at a solid-liquid ratio of 1:5 (g / mL). The mixture is stirred at room temperature at a stirring speed of 250 rpm / min for 10 min, and then filtered to obtain the third metal-rich washing solution.

[0086] Leachate impurity removal and lithium carbonate recovery:

[0087] The three washing solutions were enriched, and a certain amount of Na2S was added to them while stirring continuously until all the metal impurity ions were converted into precipitates. After removing the precipitated impurities, the pH value of the solution was adjusted, and Na2CO3 was passed into the solution at room temperature while stirring. The solution was heated in a 90°C water bath for 0.5 hours and then filtered while hot to obtain Li2CO3.

[0088] Heat treatment for recycling waste graphite powder:

[0089] The S-Gra filter residue is dried at 100℃ for 3 hours. The dried waste graphite S-Gra is then placed in a ceramic crucible and loaded into a box-type resistance furnace. Ar protective gas is introduced throughout the process, the heating rate is 5℃ / min, the sintering temperature is 800℃, the holding time is 0.5 hours, and after cooling to room temperature, reusable graphite P-Gra is obtained.

[0090] Comparative Example 1

[0091] This comparative example is used to illustrate the method for recycling and reusing graphite anode materials disclosed in this invention, including some of the operational steps in Example 1, with the following differences:

[0092] No CNTs or GPE are added to the waste graphite negative electrode powder coating.

[0093] Electrochemical performance testing:

[0094] The graphite P-Gra recovered from Examples 1-3 and Comparative Example 1 was mixed with the binder polyvinylidene fluoride (PVDF) and the conductive agent carbon black (super-P) at a mass ratio of 93:4:3. N-methylpyrrolidone (NMP) was used as a dispersant to prepare a negative electrode slurry, which was then uniformly coated onto an 8μm copper foil and dried by rolling. A lithium metal sheet was used as the counter electrode, and a three-component mixed solvent of 1 mol / L LiPF6 was used according to V... EC :V DMC :V EMC An electrolyte is prepared by mixing the components in a volume ratio of 1:1:1. A 12μm polyethylene microporous membrane is used as the separator, and the components are assembled in a glove box to form a button cell.

[0095] The coin cells prepared above were subjected to the following performance tests:

[0096] The test results are entered into Table 1.

[0097] Table 1 Test Results

[0098]

[0099] The test results from Examples 1-3 show that the capacity retention rate of the button cell batteries after 100 cycles at 1C is no less than 91%. In Example 1, when PVC ultrafine powder, CNTs, and GPE are blended with waste graphite anode powder, the initial charge-discharge efficiency reaches 94.5%, demonstrating good charge-discharge performance. Figure 1 This indicates that the battery prepared by simultaneously coating CNTs and GPE conductive and thermally conductive materials has better performance; comparing the test results of Examples 1-3 and Comparative Example 1, it can be seen that the coin cell prepared according to the method of Comparative Example 1 has relatively low cycle performance.

[0100] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for recycling a graphite negative electrode material, characterized by, Comprising the following steps: 1) Waste graphite negative electrode powder is fused and coated with PVC powder and conductive and heat-conductive carbon material; the conductive and heat-conductive carbon material is one or several of carbon nanotubes CNTs or graphene; before the waste graphite negative electrode powder is fused and coated with PVC powder and conductive and heat-conductive carbon material, the waste graphite negative electrode powder is heat treated in a protective gas, the heat treatment temperature is 150-350℃, and the time is 0.5-3h; 2) The coated waste graphite negative electrode powder is heat treated, the heating rate is 2-5℃ / min, the heat treatment temperature is 100-220℃, the heat treatment time is 20-120min, and the heat treatment atmosphere is N2, so that the metal elements in the waste graphite negative electrode powder react with the chlorine elements produced by the thermal cracking of PVC to obtain metal chloride; 3) The waste graphite negative electrode powder is washed with deionized water to leach the metal chloride, and after filtration, waste graphite negative electrode powder washing liquid and filter residue are obtained, a deimpurity agent is added to the waste graphite negative electrode powder washing liquid to remove trace copper element impurities, and a lithium ion precipitant is added to the washing liquid after impurity removal to enrich alkali metal elements; 4) Waste graphite negative electrode powder recovery heat treatment, the filter residue is dried and placed in Ar protective gas, sintered at 800℃ for 0.5h, and after cooling, reused graphite is obtained.

2. The method for recycling graphite negative electrode material according to claim 1, characterized in that, The protective gas in step 1) is one or more of Ar, N2, and Kr.

3. The method for recycling graphite negative electrode material according to claim 1, characterized in that, The mass fraction of the conductive and heat-conductive carbon material in the coated waste graphite negative electrode powder is 0.5-5wt%.

4. The method for recycling graphite negative electrode material according to claim 1, characterized in that, The mass fraction of the PVC powder in the coated waste graphite negative electrode powder is 0.5-10wt%, and the particle size of the PVC powder is ≤1μm.

5. The method for recycling graphite negative electrode material according to claim 1, characterized in that, The deimpurity agent is one or several of Na2S, K2S, NaHS, H2S, and BaS. 6.The method for recycling graphite negative electrode material according to claim 1, characterized in that, The precipitant is one or several of CO2, Na2CO3, K2CO3, and NaHCO3.

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