Regeneration method for silicon-carbon negative electrode material of spent lithium-ion battery and use thereof

Abstract

Disclosed in the present invention are a regeneration method for a silicon-carbon negative electrode material of a spent lithium-ion battery and a use thereof. The method comprises the following steps: S1, mixing a silicon-carbon negative electrode material of a spent lithium-ion battery with an alkaline substance, and calcining in a non-oxidizing atmosphere to obtain a calcined mixture; S2, washing the calcined mixture to be neutral, and performing solid-liquid separation to obtain a graphite material and a silicon-containing solution; S3, adjusting the pH of the silicon-containing solution to a level causing precipitation of silicate ions, reacting under heating, and performing solid-liquid separation to collect a silicate precipitate; S4, mixing the silicate precipitate with elemental silicon, grinding the mixture into micrometer-scale powder, calcining the powder under vacuum conditions, and collecting generated silicon monoxide; and S5, performing carbon coating treatment on the silicon monoxide and the graphite material prepared in step S2 to obtain a regenerated silicon-carbon negative electrode material. In the solution, a spent silicon-carbon negative electrode material is successfully converted into a high-quality regenerated material, which can be directly applied to production and manufacturing of a new battery.

Description

A method for regenerating silicon-carbon anode materials from spent lithium-ion batteries and its application Technical Field

[0001] This invention relates to the field of new energy technology, specifically to a method for regenerating silicon-carbon anode materials from waste lithium-ion batteries and its application. Background Technology

[0002] Lithium-ion batteries, with their significant advantages such as high energy power density, excellent cycle stability, high operating voltage, outstanding safety performance, and environmental friendliness, have been widely and deeply applied in various fields such as electric vehicles, portable electronic devices, and energy storage systems. However, as consumable products, lithium-ion batteries inevitably have a limited lifespan. As their lifespan gradually expires, if a large number of discarded batteries are not properly disposed of and recycled, the harmful substances they contain may leak into the environment, posing a serious threat to soil, water sources, and ecosystems, and ultimately affecting human health.

[0003] Meanwhile, the key materials contained in spent lithium batteries, such as lithium, cobalt, copper, and silicon-carbon, demonstrate extremely high recycling value in the context of increasingly scarce global resources. These materials are not only essential raw materials for manufacturing new batteries, but recycling them can also significantly reduce the need for primary resource extraction, thereby reducing energy consumption and environmental pollution. Therefore, the scientific and effective management and disposal of spent lithium batteries can not only effectively alleviate environmental pressure and protect the ecological environment, but also achieve resource recycling, bringing significant environmental and economic benefits.

[0004] Currently, the focus of recycling spent lithium-ion batteries is mainly on the cathode material and its metal elements, while research on the silicon-carbon anode material is relatively limited. Silicon-carbon materials, with their theoretical capacity of up to 4200 mAh / g and low plateau potential of 0.5V, have shown great application potential in high-energy-density lithium-ion batteries. However, silicon-carbon materials undergo significant volume expansion during charge-discharge cycles, leading to cracking and even pulverization of the anode material after long-term cycling. This not only compromises the structural stability of the battery but also forms a thick solid electrolyte interphase (SEI) film on the surface of the anode material, further hindering lithium-ion transport and resulting in significant losses of silicon and lithium. Furthermore, during battery cycling and dismantling, silicon-carbon anode materials may deposit and adsorb other metal elements, increasing the difficulty of recycling.

[0005] Therefore, collected waste silicon-carbon anode materials need to be further processed using advanced technologies to restore their original performance and quality. This not only helps meet the requirements for recycling and reusing silicon-carbon anode materials and improves resource utilization, but also reduces the negative environmental impact of waste batteries and promotes the sustainable development of the lithium-ion battery industry. However, there are few reports on this technology in the current field. Summary of the Invention

[0006] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a method for regenerating silicon-carbon anode materials from spent lithium-ion batteries, which can effectively achieve the regeneration of silicon-carbon anode materials.

[0007] The present invention also proposes applications of the above method.

[0008] A method for regenerating silicon-carbon anode materials from spent lithium-ion batteries according to a first aspect of the present invention includes the following steps:

[0009] S1. The silicon-carbon anode material of waste lithium-ion batteries is mixed with an alkaline substance and calcined in a non-oxidizing atmosphere to obtain a calcined mixture.

[0010] S2. The calcined mixture is washed until neutral, and solid-liquid separation is performed to obtain graphite material and silicon-containing solution;

[0011] S3. Adjust the pH of the silicon-containing solution to a level that precipitates silicate ions, react under heating, separate the solid and liquid, and collect the silicate precipitate;

[0012] S4. The silicic acid precipitate is mixed with elemental silicon, ground into micron-sized powder, and calcined under vacuum conditions to collect the generated silicon suboxide.

[0013] S5. The silicon suboxide and the graphite material obtained in step S2 are subjected to carbon coating treatment to obtain the regenerated silicon-carbon anode material.

[0014] The preparation method according to embodiments of the present invention has at least the following beneficial effects: The present invention proposes an innovative scheme that ingeniously recycles and reuses waste silicon-carbon anode materials through a series of chemical and physical treatment steps. This scheme first mixes the waste silicon-carbon anode material with an alkaline substance and calcines it under a non-oxidizing atmosphere. This step not only helps to effectively remove impurities from the material but also partially alters its structure, laying a solid foundation for subsequent processing. During calcination, the silicon component is converted into silicates. Subsequently, the graphite material can be easily separated from the silicon-containing solution through a simple water immersion treatment. Furthermore, by adjusting the pH value of the silicon-containing solution, silicic acid precipitate can be precipitated. The precipitation reaction is carried out under heating conditions; increasing the temperature of the reaction system promotes hydrolysis, accelerates the reaction rate, and makes the reaction more complete. It also accelerates the coagulation of the product from a colloidal substance into a precipitate, speeding up the aging process for easier subsequent filtration and separation. Calcination of this silicic acid precipitate together with elemental silicon generates silicon suboxide. The entire process is simple to operate and does not require the introduction of too many complex reagents, yet it successfully achieves the effective separation and reuse of silicon and carbon, significantly simplifying the recycling process and improving economic benefits.

[0015] Another major highlight of this invention lies in the ingenious combination of steps that enables the recovery of silicon and lithium elements from waste materials and their reintegration into new silicon-carbon anode materials. Simultaneously, the recovered graphite material is directly used for carbon coating, maximizing the recovery and utilization of useful components. In particular, the recovered graphite material is reused to coat the surface of silicon suboxide particles, forming a protective layer. This protective layer not only effectively alleviates the volume expansion problem of silicon, preventing the anode material from cracking and pulverizing, but also significantly enhances the overall structural stability of the material, enabling it to maintain excellent performance during long-term cycling.

[0016] In summary, this invention successfully transforms waste silicon-carbon anode materials into high-quality recycled materials through a series of meticulously designed chemical and physical processing steps. These recycled materials can be directly applied to the production of new batteries, not only reducing the difficulty and cost of recycling but also achieving efficient regeneration and recycling of materials, which is of great significance for promoting the sustainable development of the battery industry.

[0017] According to some embodiments of the present invention, the alkaline substance in step S1 includes at least one of alkali metal alkali or alkali metal carbonate.

[0018] According to some embodiments of the present invention, the alkaline substance in step S1 includes at least one of sodium hydroxide, lithium hydroxide, or sodium carbonate.

[0019] According to some embodiments of the present invention, the mass ratio of the silicon-carbon anode material of the waste lithium-ion battery to the alkaline substance in step S1 is 5:1 to 5:6.

[0020] According to some embodiments of the present invention, the non-oxidizing atmosphere includes at least one of carbon dioxide, nitrogen, or an inert gas.

[0021] According to some embodiments of the present invention, the calcination temperature in step S1 is 300℃~700℃; and / or the time is 4~5h.

[0022] According to some embodiments of the present invention, the washing in step S2 is a water wash.

[0023] According to some embodiments of the present invention, the number of water washes is 3 to 5.

[0024] According to some embodiments of the present invention, during the water washing process, the liquid-solid ratio of water to the calcined mixture is 4:1 to 8:1.

[0025] According to some embodiments of the present invention, in step S3, the pH is adjusted to 1.5 to 3.0.

[0026] According to some embodiments of the present invention, acid is used to adjust the pH in step S3.

[0027] According to some embodiments of the present invention, the acid is a sulfuric acid, hydrochloric acid, or nitric acid solution.

[0028] According to some embodiments of the present invention, the concentration of the sulfuric acid solution is 1 mol / L to 2.5 mol / L, the concentration of the hydrochloric acid solution is 1 mol / L to 4 mol / L, and the concentration of the nitric acid solution is 1 mol / L to 2 mol / L. Hydrochloric acid and nitric acid are volatile under heating conditions; therefore, sulfuric acid is preferred.

[0029] According to some embodiments of the present invention, the heating temperature in step S3 is 70-90°C.

[0030] According to some embodiments of the present invention, in step S4, the silica precipitate and elemental silicon are mixed in a molar ratio of 1:0.8 to 1:1.2.

[0031] According to some embodiments of the present invention, in step S4, the calcination temperature is 1200-1800°C.

[0032] According to some embodiments of the present invention, in step S4, the calcination time is 4 to 5 hours.

[0033] According to some embodiments of the present invention, in step S5, the silicon suboxide and graphite material are mixed in a mass ratio of 10:1 to 10:1.4.

[0034] According to some embodiments of the present invention, in step S5, the carbon coating treatment includes sintering, and the sintering conditions include at least one of the following:

[0035] 1) Sintering in a CVD atmosphere furnace (chemical vapor deposition atmosphere furnace);

[0036] 2) The sintering temperature is 1000–1200℃;

[0037] 3) The sintering time is 8 to 10 hours.

[0038] Carbon coating provides better electronic conductivity while reducing the formation of the SEI film, thereby improving lithium-ion transport efficiency. Using a CVD furnace allows for precise control of reaction conditions, such as temperature, gas flow rate, and reaction time, enabling precise control over the thickness, structure, and properties of the carbon coating layer.

[0039] Applications according to a second aspect of the present invention include the application of the above-described method in the preparation of lithium-ion batteries.

[0040] According to the embodiments of the present invention, the method for regenerating lithium-ion battery anode materials has at least the following beneficial effects: The method for regenerating lithium-ion battery anode materials of the present invention shows broad application prospects in the field of lithium-ion battery preparation and recycling. This method significantly reduces costs and improves overall economic efficiency by optimizing the regeneration process. Specifically, it can not only effectively recover silicon, lithium, graphite, etc., from waste lithium-ion battery anode materials, but also achieve efficient reuse of these materials through innovative regeneration technology, thereby significantly reducing raw material costs while ensuring battery performance. Furthermore, this method emphasizes environmental protection and sustainability, reduces waste emissions, conforms to the development trend of green manufacturing, and further enhances its market competitiveness and economic benefits. Therefore, the lithium-ion battery regeneration method of the present invention is not only cost-effective, but also provides strong support for the sustainable development of the lithium-ion battery industry.

[0041] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0042] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0043] Figure 1 is a SEM image of the waste silicon-carbon anode material collected before processing in Example 1 of the present invention;

[0044] Figure 2 is a SEM image of the regenerated silicon-carbon anode material obtained in Example 1 of the present invention. Detailed Implementation

[0045] The following will clearly and completely describe the concept and technical effects of the present invention in conjunction with embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention. Unless otherwise specified, the experimental methods used in the embodiments are conventional methods; the materials and reagents used, unless otherwise specified, are commercially available. Unless otherwise specified, the same parameter value is the same in all embodiments. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0046] In the description of this invention, references to terms such as "some embodiments" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0047] The silicon-carbon anode materials from the waste lithium-ion batteries in the following examples all come from the same source and all parameters are consistent.

[0048] Example 1

[0049] This example provides a method for regenerating silicon-carbon anode materials from spent lithium-ion batteries and its application. The specific operation of the regeneration method is as follows:

[0050] (1) The collected waste silicon-carbon anode material (its SEM image is shown in Figure 1) was mixed with flake sodium hydroxide solid in a mass ratio of 5:5 and calcined at high temperature in a carbon dioxide atmosphere. The calcination temperature was 600℃ and the calcination time was 4h to obtain the calcined mixture.

[0051] (2) The calcined mixture was washed multiple times with deionized water at a liquid-solid ratio of 5:1 until neutral and then filtered to obtain graphite material for sintering to prepare lithium-ion battery anode material and silicon-containing leaching solution.

[0052] (3) Adjust the pH of the silicon-containing leaching solution to 1.5 with 1 mol / L sulfuric acid solution, and the reaction temperature is 80℃ to ensure complete precipitation of silicate ions. Filter the precipitate to obtain silicate precipitate and dry it.

[0053] (4) The silica precipitate and silicon element are mixed evenly in a 1:1 molar ratio, ground into micron-sized powder, and calcined under vacuum at a temperature of 1600℃ for 4 hours. The generated gas is collected and cooled to obtain silicon suboxide solid.

[0054] (5) Carbon coating treatment is performed on the silicon suboxide solid and the graphite material recovered in step (2). The silicon suboxide solid and the graphite material are mixed evenly at a mass ratio of 10:1.2, ground into micron-sized powder, and sintered in a CVD atmosphere furnace at a calcination temperature of 1200℃ for 10 hours. After the sintered product cools naturally to room temperature, it is passed through a 300-mesh sieve to obtain the recycled product SiO. x @C material (its SEM image is shown in Figure 2).

[0055] To regenerate SiO x A coin cell-type simulated battery was assembled in an argon-filled glove box using a silicon-carbon electrode as the working electrode, lithium metal as the negative electrode, a conductive agent, a binder, an electrolyte (1 mol / L LiPF6 dissolved in a 1:1:1 EC:DEC:DMC solvent), and a 2500-type separator (O2 < 0.01 ppm, H2O < 0.01 ppm). Electrochemical performance was tested using a constant current charge-discharge method with a cutoff voltage of 0.01–2.00 V. The material exhibited an initial reversible capacity of 2450.4 mAh / g, and after 300 cycles at a current density of 1.0 A / g, it retained a reversible capacity of 2314.8 mAh / g, representing a capacity retention of 94.5%.

[0056] Example 2

[0057] This example provides a method for regenerating silicon-carbon anode materials from spent lithium-ion batteries and its application. The difference between this method and Example 1 lies in the type of alkaline substance used. Specifically, the operation is as follows:

[0058] (1) The collected waste silicon-carbon anode material and sodium carbonate solid were mixed evenly in a mass ratio of 5:5 and calcined at high temperature in a carbon dioxide atmosphere. The calcination temperature was 600℃ and the calcination time was 4h to obtain the calcined mixture.

[0059] (2) The calcined mixture was washed multiple times with deionized water at a liquid-solid ratio of 5:1 until neutral and then filtered to obtain graphite material for sintering to prepare lithium-ion battery anode material and silicon-containing leaching solution.

[0060] (3) Adjust the pH of the silicon-containing leaching solution to 1.5 with 1 mol / L sulfuric acid solution, and the reaction temperature is 80℃ to ensure complete precipitation of silicate ions. Filter the precipitate to obtain silicate precipitate and dry it.

[0061] (4) Silicic acid precipitate and elemental silicon are mixed evenly at a 1:1 molar ratio, ground into micron-sized powder, and calcined under vacuum at 1600℃ for 4 hours. The generated gas is collected and cooled to obtain solid silicon suboxide.

[0062] (5) Carbon coating treatment is performed on the silicon suboxide solid and the graphite material in step b). The silicon suboxide solid and the graphite material are mixed evenly at a mass ratio of 10:1.2, ground into micron-sized powder, and sintered in a CVD atmosphere furnace at a calcination temperature of 1200℃ for 10 hours. After the sintered product cools naturally to room temperature, it is passed through a 300-mesh sieve to obtain the recycled product SiO. x @C material

[0063] With the regenerated SiO x A coin cell-type simulated battery was assembled in an argon-filled glove box using a silicon-carbon electrode as the working electrode, lithium metal as the negative electrode, a conductive agent, a binder, an electrolyte (1 mol / L LiPF6 dissolved in a 1:1:1 EC:DEC:DMC solvent), and a 2500-type separator (O2 < 0.01 ppm, H2O < 0.01 ppm). Electrochemical performance was tested using a constant current charge-discharge method with a cutoff voltage of 0.01–2.00 V. The material exhibited an initial reversible capacity of 1650.9 mAh / g, and after 300 cycles at a current density of 1.0 A / g, it retained a reversible capacity of 1281.2 mAh / g, representing a capacity retention of 77.6%.

[0064] Example 3

[0065] This example provides a method for regenerating silicon-carbon anode materials from waste lithium-ion batteries and its application. The difference between this method and Example 1 is that the type and concentration of the acid solution in step (3) are different.

[0066] (1) The collected waste silicon-carbon anode material and the sheet-like sodium hydroxide solid were mixed evenly in a mass ratio of 5:5 and calcined at high temperature in a carbon dioxide atmosphere. The calcination temperature was 600℃ and the calcination time was 4h to obtain the calcined mixture.

[0067] (2) The calcined mixture was washed multiple times with deionized water at a liquid-solid ratio of 5:1 until neutral and then filtered to obtain graphite material for sintering to prepare lithium-ion battery anode material and silicon-containing leaching solution.

[0068] (3) Adjust the pH of the silicon-containing leaching solution to 1.5 with 2 mol / L hydrochloric acid solution, and the reaction temperature is 80℃ to ensure complete precipitation of silicate ions. Filter to obtain silica precipitate and dry.

[0069] (4) The silica precipitate and silicon element are mixed evenly in a 1:1 molar ratio, ground into micron-sized powder, and calcined under vacuum at a temperature of 1600℃ for 4 hours. The generated gas is collected and cooled to obtain silicon suboxide solid.

[0070] (5) Carbon coating treatment is performed on the silicon suboxide solid and the graphite material in step b). The silicon suboxide solid and the graphite material are mixed evenly at a mass ratio of 10:1.2, ground into micron-sized powder, and sintered in a CVD atmosphere furnace at a calcination temperature of 1200℃ for 10 hours. After the sintered product cools naturally to room temperature, it is passed through a 300-mesh sieve to obtain the recycled product SiO. x @C material.

[0071] With the regenerated SiO x A coin cell-type simulated battery was assembled in an argon-filled glove box using a silicon-carbon electrode as the working electrode, lithium metal as the negative electrode, a conductive agent, a binder, an electrolyte (1 mol / L LiPF6 dissolved in a 1:1:1 EC:DEC:DMC solvent), and a 2500-type separator (O2 < 0.01 ppm, H2O < 0.01 ppm). Electrochemical performance was tested using a constant current charge-discharge method with a cutoff voltage of 0.01–2.00 V. The material exhibited an initial reversible capacity of 1982.2 mAh / g, and after 300 cycles at a current density of 1.0 A / g, it retained a reversible capacity of 1591.7 mAh / g, representing a capacity retention of 80.3%.

[0072] Example 4

[0073] This example provides a method for regenerating silicon-carbon anode materials from waste lithium-ion batteries and its application. The difference between this method and Example 1 is that in step (4), silica precipitate and elemental silicon are mixed in a 1:1.2 molar ratio, while other operations and parameters are the same as in Example 1.

[0074] (1) The collected waste silicon-carbon anode material and the sheet-like sodium hydroxide solid were mixed evenly in a mass ratio of 5:5 and calcined at high temperature in a carbon dioxide atmosphere. The calcination temperature was 600℃ and the calcination time was 4h to obtain the calcined mixture.

[0075] (2) The calcined mixture was washed multiple times with deionized water at a liquid-solid ratio of 5:1 until neutral and then filtered to obtain graphite material for sintering to prepare lithium-ion battery anode material and silicon-containing leaching solution.

[0076] (3) Adjust the pH of the silicon-containing leaching solution to 1.5 with 1 mol / L sulfuric acid solution, and the reaction temperature is 80℃ to ensure complete precipitation of silicate ions. Filter the precipitate to obtain silicate precipitate and dry it.

[0077] (4) The silica precipitate and silicon element are mixed evenly in a 1:1 molar ratio, ground into micron-sized powder, and calcined under vacuum at a temperature of 1600℃ for 4 hours. The generated gas is collected and cooled to obtain silicon suboxide solid.

[0078] (5) Carbon coating treatment is performed on the silicon suboxide solid and the graphite material in step b). The silicon suboxide solid and the graphite material are mixed evenly at a mass ratio of 10:1.2, ground into micron-sized powder, and sintered in a CVD atmosphere furnace at a calcination temperature of 1200℃ for 10 hours. After the sintered product cools naturally to room temperature, it is passed through a 300-mesh sieve to obtain the recycled product SiO. x @C material.

[0079] With the regenerated SiO x A coin cell-type simulated battery was assembled in an argon-filled glove box using a silicon-carbon electrode as the working electrode, lithium metal as the negative electrode, a conductive agent, a binder, an electrolyte (1 mol / L LiPF6 dissolved in a 1:1:1 EC:DEC:DMC solvent), and a 2500-type separator (O2 < 0.01 ppm, H2O < 0.01 ppm). Electrochemical performance was tested using a constant current charge-discharge method with a cutoff voltage of 0.01–2.00 V. The material exhibited an initial reversible capacity of 2138.5 mAh / g, and after 300 cycles at a current density of 1.0 A / g, it retained a reversible capacity of 1925.3 mAh / g, representing a capacity retention of 90.03%.

[0080] Example 5

[0081] This example provides a method for regenerating silicon-carbon anode materials from waste lithium-ion batteries and its application. The difference between this method and Example 1 is that the only difference is that in step (5), silicon suboxide solid and graphite material are mixed uniformly at a mass ratio of 10:1. All other operations and parameters are the same as in Example 1.

[0082] (1) The collected waste silicon-carbon anode material and the sheet-like sodium hydroxide solid were mixed evenly in a mass ratio of 5:5 and calcined at high temperature in a carbon dioxide atmosphere. The calcination temperature was 600℃ and the calcination time was 4h to obtain the calcined mixture.

[0083] (2) The calcined mixture was washed multiple times with deionized water at a liquid-solid ratio of 5:1 until neutral and then filtered to obtain graphite material for sintering to prepare lithium-ion battery anode material and silicon-containing leaching solution.

[0084] (3) Adjust the pH of the silicon-containing leaching solution to 1.5 with 1 mol / L sulfuric acid solution, and the reaction temperature is 80℃ to ensure complete precipitation of silicate ions. Filter the precipitate to obtain silicate precipitate and dry it.

[0085] (4) The silica precipitate and silicon element are mixed evenly in a 1:1 molar ratio, ground into micron-level powder, and calcined under vacuum at a temperature of 1000℃ for 4 hours. The generated gas is collected and cooled to obtain silicon suboxide solid.

[0086] (5) Carbon coating treatment is performed on the silicon suboxide solid and the graphite material from step b). The silicon suboxide solid and the graphite material are mixed evenly at a mass ratio of 10:1, ground into micron-sized powder, and sintered in a CVD atmosphere furnace at a calcination temperature of 1200℃ for 10 hours. After the sintered product has naturally cooled to room temperature, it is passed through a 300-mesh sieve to obtain the recycled product SiO. x @C material.

[0087] With the regenerated SiO x A coin cell-type simulated battery was assembled in an argon-filled glove box using a silicon-carbon electrode as the working electrode, lithium metal as the negative electrode, a conductive agent, a binder, an electrolyte (1 mol / L LiPF6 dissolved in a 1:1:1 EC:DEC:DMC solvent), and a 2500-type separator (O2 < 0.01 ppm, H2O < 0.01 ppm). Electrochemical performance was tested using a constant current charge-discharge method with a cutoff voltage of 0.01–2.00 V. The material exhibited an initial reversible capacity of 2075.6 mAh / g, and after 300 cycles at a current density of 1.0 A / g, it retained a reversible capacity of 1830.3 mAh / g, representing a capacity retention of 88.2%.

[0088] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for regenerating silicon-carbon anode materials from waste lithium-ion batteries, characterized in that: Includes the following steps: S1. The silicon-carbon anode material of waste lithium-ion batteries is mixed with an alkaline substance and calcined in a non-oxidizing atmosphere to obtain a calcined mixture. S2. The calcined mixture is washed until neutral, and solid-liquid separation is performed to obtain graphite material and silicon-containing solution; S3. Adjust the pH of the silicon-containing solution to a level that precipitates silicate ions, react under heating, separate the solid and liquid, and collect the silicate precipitate; S4. The silicic acid precipitate is mixed with elemental silicon, ground into micron-sized powder, and calcined under vacuum conditions to collect the generated silicon suboxide. S5. Carbon coating treatment is performed on silicon suboxide and the graphite material obtained in step S2 to obtain regenerated silicon-carbon anode material.

2. The method for regenerating silicon-carbon anode materials from waste lithium-ion batteries according to claim 1, characterized in that: The alkaline substance in step S1 includes at least one of alkali metal alkali or alkali metal carbonate.

3. The method for regenerating silicon-carbon anode materials from waste lithium-ion batteries according to claim 1, characterized in that: In step S1, the mass ratio of the silicon-carbon anode material from the waste lithium-ion battery to the alkaline substance is 5:1 to 5:

6.

4. The method for regenerating silicon-carbon anode materials from waste lithium-ion batteries according to claim 1, characterized in that: The alkaline substance in step S1 includes at least one of sodium hydroxide, lithium hydroxide, or sodium carbonate; and / or the non-oxidizing atmosphere includes at least one of carbon dioxide, nitrogen, or an inert gas.

5. The method for regenerating silicon-carbon anode materials from waste lithium-ion batteries according to claim 1, characterized in that: In step S1, the calcination temperature is 300℃~700℃; and / or the time is 4~5h.

6. The method for regenerating silicon-carbon anode materials from waste lithium-ion batteries according to claim 1, characterized in that: In step S3, the pH is adjusted to 1.5–3.

0.

7. The method for regenerating silicon-carbon anode materials from waste lithium-ion batteries according to claim 1, characterized in that: The heating temperature in step S3 is 70–90°C.

8. The method for regenerating silicon-carbon anode materials from waste lithium-ion batteries according to claim 1, characterized in that: In step S4, the calcination temperature is 1200–1800℃; and / or the calcination time is 4–5 h.

9. The method for regenerating silicon-carbon anode materials from waste lithium-ion batteries according to claim 1, characterized in that: In step S5, the carbon coating process includes sintering, and the sintering conditions include at least one of the following: 1) The silicon suboxide and graphite material are mixed in a mass ratio of 10:1 to 10:1.4; 2) Sintering in a CVD atmosphere furnace; 3) The sintering temperature is 1000–1200℃; 4) The sintering time is 8 to 10 hours.

10. The application of the method according to any one of claims 1 to 9 in the preparation of lithium-ion batteries.

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