A direct repair and regeneration method for retired lithium-ion batteries without pre-separation

Abstract

The present invention discloses a direct repair and regeneration method for retired lithium-ion batteries without pre-separation, the method comprising the following steps: after the waste lithium-ion battery is fully discharged, disassembling and stripping out the positive electrode material strip; mixing a lithium source, a reducing agent and a dipolar aprotic solvent to prepare a lithium source solution; mixing the positive electrode material strip with the lithium source solution, heating the reaction at 60-100 ° C, and after the reaction is completed, obtaining by centrifugation and screening: a mixed solution comprising a lithium source, a dipolar aprotic solvent and a binder, a regenerated precursor and a current collector; calcining the regenerated precursor after mixing with lithium carbonate to obtain a regenerated lithium battery positive electrode material. The method provided by the present invention can realize the repair and regeneration of the positive electrode material while separating the positive electrode material, the binder and the current collector, overcomes the complex operation problem of separating the pretreatment and the regeneration process in the traditional hydrothermal regeneration process, and simplifies the process flow.

Description

Technical Field

[0001] The present invention relates to the field of recycling and regenerating retired lithium-ion batteries, and in particular to a method for directly repairing and regenerating retired lithium-ion batteries without the need for pre-separation. Background Art

[0002] The current global energy landscape is transitioning from a focus on traditional fossil fuels to one that is clean and efficient. The intermittent and unstable nature of renewable energy, particularly photovoltaic and wind power, has accelerated the development of new energy storage technologies. By 2023, China's total lithium battery production will reach 940GWh, with the industry's total output value exceeding 1.4 trillion yuan, ranking first globally. Lithium batteries are primarily used in new energy electric vehicles (domestic production and sales in 2023 will reach 9.5 million units, with exports reaching 1.2 million units, both ranking first globally) and electrochemical energy storage power stations (by the end of 2023, 1,375 stations will have been built nationwide, with a total installed capacity of 45.43GW).

[0003] With the widespread adoption of lithium batteries, a peak in their retirement is approaching. The calendar life of a power lithium battery is approximately 10 years. For non-commercial private vehicles, the service life is generally 8 years or 150,000 kilometers, while for commercial vehicles, it's 6 years or 600,000 kilometers. The design life of energy storage lithium batteries requires more than 3,500 cycles, but due to their high-frequency charge and discharge characteristics, the actual design life of energy storage power stations is 8 to 10 years. Currently, China is experiencing a peak in the retirement of its first batch of power and energy storage lithium batteries. By 2023, the cumulative volume of retired lithium batteries reached 590,000 tons, with a market value of 40 billion yuan. The market for retired lithium batteries is expected to grow to 150 billion yuan by 2030.

[0004] Lithium battery positive electrode materials primarily consist of inorganic compounds containing large amounts of valuable metal elements, such as lithium manganese oxide, lithium cobalt oxide, lithium nickel cobalt manganese oxide, and lithium iron phosphate. Currently, the prices of various positive electrode materials are relatively high, with ternary lithium costing 110,000 yuan per ton, lithium cobalt oxide 150,000 yuan per ton, lithium manganese oxide 34,000 yuan per ton, and lithium iron phosphate 34,500 yuan per ton. In ternary lithium batteries, the cost of positive electrode materials accounts for 57% of the total battery cost, while in lithium iron phosphate batteries, the cost of positive electrode materials accounts for 40%. Therefore, positive electrode materials are the most valuable component of used lithium batteries for recycling. Recycling technologies for used lithium-ion batteries focus on recovering the valuable metals in the positive electrode materials. Currently, the main recycling methods for used lithium-ion batteries include hydrometallurgy and pyrometallurgy.

[0005] The pyrometallurgical process, which uses high temperatures to extract and purify metals from spent lithium-ion batteries, is a complex multi-step process involving roasting, smelting, and refining. During roasting, the electrode material is heated in air to eliminate volatile components and other impurities. During smelting, the roasted electrode material is melted with a reducing agent to remove any remaining impurities and produce pure metal. Finally, during refining, the metal is further purified through various techniques, such as electrolysis or distillation.

[0006] Hydrometallurgy, a low-temperature processing technology, is widely used in the extraction of metal ores and the recycling of secondary resources such as spent lithium-ion batteries. The core of this process is the efficient extraction of valuable metals from ores or concentrates through acid or alkaline leaching. The leachate is then converted into a high-purity cathode material precursor using preparation methods such as co-precipitation or sol-gel methods.

[0007] Unlike hydrometallurgy and pyrometallurgy, direct regeneration technology focuses on the degradation mechanism of cathode materials and has successfully developed a targeted lithium replenishment and structural repair process with simple procedures, low production costs, and low waste liquid emissions. Compared with the original form, the structure and composition of the cathode material undergo significant changes after a long period of electrochemical cycling. These changes are mainly attributed to the loss of Li+ within the crystal lattice, the leaching of transition metal elements, and the formation of cracks on the surface of the material. The direct regeneration process can effectively replenish the missing components in the material, thereby achieving structural repair at the molecular level. Among them, the most industrially promising direct regeneration method is the hydrothermal method, which mixes the waste cathode material with a lithium source solution of a certain concentration, places it in a high-pressure reactor, heats it at a certain temperature and pressure, and then anneals it to obtain the regenerated cathode material.

[0008] However, the traditional hydrothermal method usually requires two key steps: pre-separation and hydrothermal reaction. Carrying out pretreatment (separation of cathode material, binder, and aluminum foil) and hydrothermal reaction (regeneration of cathode material) as two separate steps has the following disadvantages:

[0009] 1. Complex process flow with numerous steps: Since separation and regeneration are independent processes, additional equipment and processes are required to process the materials. The separation process typically includes discharge, crushing, screening, solvent immersion, and other steps, each of which increases time and cost. This multi-step process brings complex coordination and management, requiring strict control of conditions at each step, increasing production costs and technical difficulty.

[0010] 2. High energy and resource consumption: Multi-step operations require independent energy input for each step (e.g., heating, solvent treatment, evaporation). Chemical solvents (e.g., NMP) used in the separation process are expensive and require additional wastewater treatment, increasing the risk of environmental pollution. Each step in the step-by-step process requires a long reaction time, increasing the overall recovery cycle and leading to high energy consumption.

[0011] 3. High risk of material loss and contamination: During the independent pre-separation process, binders (such as PVDF) may degrade or become unrecyclable, resulting in resource waste. Aluminum foil is easily damaged during the physical or chemical separation process, losing its recycling value or becoming contaminated, thereby reducing its reuse efficiency.

[0012] 4. Wastewater treatment and environmental burden: The use of organic solvents (such as NMP) and other chemical substances generates a large amount of wastewater, which requires further treatment, increasing wastewater management costs and environmental risks. If pre-separation is not thorough, residual solvents may contaminate the recycled materials and affect subsequent battery preparation.

[0013] 5. Poor economic benefits: Because traditional methods can only partially recover certain components in lithium batteries (such as the binder PVDF or cathode materials), the overall material recovery rate is low. In the absence of a one-step process, companies need to invest additional equipment and energy to complete pretreatment and regeneration, resulting in a decline in overall economic benefits.

[0014] Currently, no patents combine pre-separation with the hydrothermal reaction process. For example, Chinese patent publication number CN118676464A only discusses the use of asphalt as a reducing agent to regenerate cathode materials. Furthermore, CN111100324A discloses a method for recycling PVDF, a binder used in used lithium batteries. The method involves soaking and dissolving deeply discharged and crushed battery cells in the organic solvent N-methylpyrrolidone (NMP), followed by filtration and vacuum distillation to obtain the PVDF binder. This method only separates the cathode material from the binder and does not simultaneously regenerate the cathode material.

[0015] In summary, combining pretreatment with hydrothermal reaction process to design a synchronous recovery process can significantly simplify the operation process, reduce equipment requirements, and reduce process complexity, which is currently a research hotspot in this field. Summary of the Invention

[0016] This invention aims to provide a direct regeneration method for retired lithium-ion batteries that does not require pre-separation. Based on the principle of solvothermal reaction, this method utilizes a reducing solvent system consisting of a dipolar aprotic solvent, a lithium salt, and a green reducing agent. This method can simultaneously separate the cathode material, binder, and current collector while simultaneously regenerating the cathode material. This method overcomes the complex operational challenges of separating the pretreatment and regeneration processes in traditional hydrothermal regeneration processes, simplifying the process flow.

[0017] The present invention provides the following technical solutions:

[0018] A method for directly repairing and regenerating retired lithium-ion batteries without pre-separation, the regeneration method comprising the following steps:

[0019] (1) Discharge and disassembly: After the waste lithium-ion battery is fully discharged, it is disassembled and the positive electrode material strip is peeled off;

[0020] (2) preparing a lithium source solution: mixing a lithium source, a reducing agent, and a dipolar aprotic solvent to prepare a lithium source solution;

[0021] (3) Solvothermal reaction: The positive electrode material strip is mixed with the lithium source solution and heated at 60-100 °C for reaction. After the reaction is completed, a mixed solution containing the lithium source, dipolar aprotic solvent and binder is obtained by centrifugation and sieving, and the precursor and current collector are regenerated;

[0022] (4) Annealing: The regenerated precursor is mixed with lithium carbonate and then calcined to obtain a regenerated lithium battery positive electrode material.

[0023] The invention realizes low-temperature solvent thermal reaction of the positive electrode material of the waste lithium battery by adding different reducing agents to a lithium source solution and mixing the solution with the positive electrode strip of the waste lithium battery, and performing solvent thermal reaction, drying and annealing.

[0024] The core technical idea of ​​the present invention is: first, the waste lithium battery positive electrode strip is obtained by disassembling the battery; then, a mixed solution containing a lithium source, a reducing agent and a dipolar aprotic solvent is used to replenish lithium and remove the binder from the positive electrode strip; then, after a short period of annealing treatment, the material structure is repaired, thereby obtaining a regenerated positive electrode material with high capacity and excellent cycle stability.

[0025] In step (2), the dipolar aprotic solvent is selected from one or a combination of at least two of N-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO), dimethylformamide (DMF), acetone, dimethylacetamide (DMAc), 5-dimethylamino-2-methyl-5-oxopentanoate (PolarClean), acetyl triethyl citrate (ATEC), dibutyl phthalate (DBP), dibutyl sebacate (DBS), diethyl phthalate (DEP), hexamethylphosphoric triamide (HMPA), triethyl citrate (TEC), triacetin, trimethyl phosphate (TMP) or tetrabutyl succinamide (TBSA).

[0026] In step (2), the reducing agent is selected from one or a combination of at least two or more of glucose, xylose, erythrose, glucitol, xylitol, erythritol, cellulose, chitin, and lignin.

[0027] In step (2), the lithium source is selected from one or a combination of at least two of lithium chloride, lithium nitrate, lithium sulfate, lithium hydroxide, lithium bis(trifluoromethanesulfonyl)imide, lithium bromide, lithium iodide, and lithium acetate.

[0028] The method further comprises:

[0029] (5) Binder regeneration: The mixed solution containing the binder and the dipolar aprotic solvent prepared in step (3) is applied to the glass surface and slowly immersed in water to prepare a binder film (PVDF film) and a mixed solution of the dipolar aprotic solvent and water.

[0030] Furthermore, the method further comprises: (6) separation of solvent and water: using a fractionation column to separate the mixed solution in step (5), and utilizing the difference in boiling points between the dipolar aprotic solvent and water to recover pure dipolar aprotic solvent and water respectively.

[0031] Furthermore, the dipolar aprotic solvent is selected from N-methylpyrrolidone, dimethyl sulfoxide, triethyl citrate, tetrabutyl succinamide, dimethylacetamide, or dimethylamino-2-methyl-5-oxopentanoate; the reducing agent is selected from glucose, erythritol, erythrose, cellulose, or xylose; and the lithium source is selected from lithium chloride, lithium hydroxide, or lithium sulfate. By regulating the type of lithium source solution, the present invention achieves efficient separation and regeneration of the positive electrode material and the current collector, while also enabling the regenerated lithium battery to have high capacity and cycle stability.

[0032] Further preferably, the dipolar aprotic solvent is selected from N-methylpyrrolidone, dimethyl sulfoxide, triethyl citrate, or tetrabutyl succinamide; the reducing agent is selected from glucose, erythritol, or erythrose; and the lithium source is selected from lithium chloride or lithium hydroxide. By further optimizing the type of lithium source solution, the present invention enables the regenerated lithium battery to have higher capacity and cycle stability.

[0033] This invention not only effectively recycles waste lithium batteries, avoiding resource waste, but also allows the reagents used to be recycled, thus meeting environmental protection requirements. Furthermore, the introduction of a dipolar aprotic solvent organically integrates the pretreatment and regeneration processes, reducing overall costs and improving regeneration efficiency and material performance.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] (1) The present invention utilizes a dipolar aprotic solvent to cause a swelling reaction with a binder (polyvinylidene fluoride PVDF) under high temperature conditions, and simultaneously forms a lithium bond between lithium ions in the lithium source and fluorine elements in PVDF, thereby accelerating the dissolution of PVDF and achieving efficient separation of the positive electrode material and the current collector.

[0036] (2) The present invention utilizes a specific solvent system, a dipolar aprotic solvent to dissolve the lithium source and binder, and adopts an inexpensive green reducing agent to reduce the energy barrier of the regeneration reaction, thereby achieving a combination of the pretreatment process and the regeneration process. This regeneration process using a reducing solvent thermal reaction system significantly reduces the number of operating steps and simplifies the entire process, thereby achieving efficient regeneration of retired lithium-ion batteries.

[0037] (3) The reagents and materials used in the entire process of the present invention are all recyclable and reusable. During this process, the binder, current collector, dipolar aprotic solvent, lithium source, and cathode material are all effectively separated and used for subsequent recovery and regeneration operations. The current collector maintains its structural integrity, with no cathode material or binder residue on its surface. The binder is structurally intact and can be used normally. The dipolar aprotic solvent is separated from water by fractionation technology, ensuring its recyclability.

[0038] (4) The present invention can achieve effective separation of the current collector and the positive electrode material, and the residual rate of the current collector (such as aluminum) in the regenerated positive electrode material is less than 0.05wt%, ensuring the purity and regeneration performance of the material.

[0039] (5) The regenerated lithium battery prepared by the present invention exhibits excellent electrochemical performance, high capacity and cycle stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1This is a specific flow chart of the method for directly repairing and regenerating retired lithium-ion batteries without pre-separation in an embodiment.

[0041] Figure 2 This is a comparison curve of the cycling performance of the recycled ternary lithium material and the waste ternary lithium material obtained in Example 1 at a current density of 0.1C: During the test, the charge and discharge voltage range was set to 2.8V to 4.3V.

[0042] Figure 3 This is a comparison curve of the cycling performance of the recycled ternary lithium material and the waste ternary lithium material obtained in Example 2 at a current density of 0.1C: During the test, the charge and discharge voltage range was set to 2.8V to 4.3V.

[0043] Figure 4 This is a comparison curve of the cycling performance of the recycled ternary lithium material and the waste ternary lithium material obtained in Example 3 at a current density of 0.1C: During the test, the charge and discharge voltage range was set to 2.8V to 4.3V.

[0044] Figure 5 This is a comparison curve of the cycling performance of the recycled ternary lithium material and the waste ternary lithium material obtained in Example 4 at a current density of 0.1C: During the test, the charge and discharge voltage range was set to 2.8V to 4.3V.

[0045] Figure 6 This is a comparison curve of the cycling performance of the recycled ternary lithium material and the waste ternary lithium material obtained in Example 5 at a current density of 0.1C: During the test, the charge and discharge voltage range was set to 2.8V to 4.3V.

[0046] Figure 7 This is a comparison curve of the cycling performance of the recycled ternary lithium material and the waste ternary lithium material obtained in Example 6 at a current density of 0.1C: During the test, the charge and discharge voltage range was set to 2.8V to 4.3V.

[0047] Figure 8 This is a comparison curve of the cycling performance of the recycled ternary lithium material and the waste ternary lithium material obtained in Example 7 at a current density of 0.1C: During the test, the charge and discharge voltage range was set to 2.8V to 4.3V. DETAILED DESCRIPTION

[0048] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings and specific embodiments.

[0049] Example 1

[0050] like Figure 1 As shown, the method for regenerating waste lithium batteries provided in this embodiment specifically includes the following steps:

[0051] (1) Disassembly and discharge: Use a charge and discharge tester to discharge the used lithium battery at a current of 1 A until the voltage drops to 2 V. Subsequently, the battery is placed in a glove box for disassembly, the positive electrode material strip is peeled off, and the positive electrode strip is rinsed twice with dimethyl carbonate (purity >99%) to remove the residual electrolyte on the surface.

[0052] (2) Solution preparation: 40 mL of N-methylpyrrolidone (NMP), 3 g of glucose, and 3 g of lithium chloride were mixed at room temperature to prepare a solution, ensuring that the solutes were uniformly dissolved.

[0053] (3) Solvothermal reaction: Weigh 2 g of the positive electrode tape treated in step (1), add it to the mixed solution prepared in step (2), and pour it into a reactor. Place the reactor in an oven and heat it to 80°C for 8 hours. After the reaction is completed, cool it to room temperature and centrifuge it at 9000 rpm for 5 minutes to separate the solution and solid product. Subsequently, dry the solid at 120°C for 12 hours and sieve it to obtain aluminum foil and positive electrode powder.

[0054] (4) Annealing: After weighing the regenerated precursor, lithium carbonate (purity >99%) was added at a ratio of 5% and evenly ground in a mortar. The mixture was then poured into a porcelain boat and heated in a tube furnace at 850°C for 4 hours. After cooling, the regenerated positive electrode powder was obtained.

[0055] (5) Binder regeneration step: Using a film forming apparatus, the NMP solution of PVDF and lithium chloride obtained in step (3) is uniformly coated on the glass surface. Subsequently, the coated glass is slowly immersed in deionized water for 5 minutes to form a PVDF film while retaining the mixed solution of NMP, deionized water, and lithium chloride.

[0056] (6) Separation step of the dipolar aprotic solvent and water: the mixed solution in step (6) is poured into a distillation flask, heated to 100° C., and the deionized water is evaporated to separate the dipolar aprotic solvent and the deionized water.

[0057] Testing and characterization: The regenerated cathode material was characterized by inductively coupled plasma mass spectrometry (ICP) analysis. At the same time, the regenerated cathode material was assembled into a button half-cell and the charge and discharge test was carried out under the test conditions of 2.8V-4.3V voltage range and 0.1C current density. The test results are as follows: Figure 2 shown.

[0058] Example 2

[0059] like Figure 1 As shown, the method for regenerating waste lithium batteries provided in this embodiment specifically includes the following steps:

[0060] (1) Disassembly and discharge: Use a charge and discharge tester to discharge the used lithium battery at a current of 1 A until the voltage drops to 2 V. Subsequently, the battery is placed in a glove box for disassembly, the positive electrode material strip is peeled off, and the positive electrode strip is rinsed twice with dimethyl carbonate (purity >99%) to remove the residual electrolyte on the surface.

[0061] (2) Solution preparation: 40 mL of dimethyl sulfoxide (DMSO), 3 g of erythritol, and 3 g of lithium hydroxide were mixed at room temperature to prepare a solution, ensuring that the solutes were uniformly dissolved.

[0062] (3) Solvothermal reaction: Weigh 2 g of the positive electrode tape treated in step (1), add it to the mixed solution prepared in step (2), and pour it into a reactor. Place the reactor in an oven and heat it to 80°C for 8 hours. After the reaction is completed, cool it to room temperature and centrifuge it at 9000 rpm for 5 minutes to separate the solution and solid product. Subsequently, dry the solid at 120°C for 12 hours and sieve it to obtain aluminum foil and positive electrode powder.

[0063] (4) Annealing: After weighing the regenerated precursor, lithium carbonate (purity >99%) was added at a ratio of 5% and evenly ground in a mortar. The mixture was then poured into a porcelain boat and heated in a tube furnace at 850°C for 4 hours. After cooling, the regenerated positive electrode powder was obtained.

[0064] (5) Binder regeneration step: Using a film forming apparatus, the DMSO solution of PVDF and lithium chloride obtained in step (3) was uniformly coated on the glass surface. Subsequently, the coated glass was slowly immersed in deionized water for 5 minutes to prepare a PVDF film while retaining the mixed solution of DMSO, deionized water, and lithium chloride.

[0065] (6) Separation step of the dipolar aprotic solvent and water: the mixed solution in step (6) is poured into a distillation flask, heated to 100° C., and the deionized water is evaporated to separate the dipolar aprotic solvent and the deionized water.

[0066] Testing and characterization: The regenerated cathode material was characterized by inductively coupled plasma mass spectrometry (ICP) analysis. At the same time, the regenerated cathode material was assembled into a button half-cell and the charge and discharge test was carried out under the test conditions of 2.8V-4.3V voltage range and 0.1C current density. The test results are as follows: Figure 3 shown.

[0067] Example 3

[0068] like Figure 1 As shown, the method for regenerating waste lithium batteries provided in this embodiment specifically includes the following steps:

[0069] (1) Disassembly and discharge: Use a charge and discharge tester to discharge the used lithium battery at a current of 1 A until the voltage drops to 2 V. Subsequently, the battery is placed in a glove box for disassembly, the positive electrode material strip is peeled off, and the positive electrode strip is rinsed twice with dimethyl carbonate (purity >99%) to remove the residual electrolyte on the surface.

[0070] (2) Solution preparation: 40 mL of dimethylacetamide (DMAc), 1 g of cellulose, and 3 g of lithium chloride were mixed at room temperature to prepare a solution, ensuring that the solutes were uniformly dissolved.

[0071] (3) Solvothermal reaction: Weigh 2 g of the positive electrode tape treated in step (1), add it to the mixed solution prepared in step (2), and pour it into a reactor. Place the reactor in an oven and heat it to 80°C for 8 hours. After the reaction is completed, cool it to room temperature and centrifuge it at 9000 rpm for 5 minutes to separate the solution and solid product. Subsequently, dry the solid at 120°C for 12 hours and sieve it to obtain aluminum foil and positive electrode powder.

[0072] (4) Annealing: After weighing the regenerated precursor, lithium carbonate (purity >99%) was added at a ratio of 5% and evenly ground in a mortar. The mixture was then poured into a porcelain boat and heated in a tube furnace at 850°C for 4 hours. After cooling, the regenerated positive electrode powder was obtained.

[0073] (5) Binder regeneration step: The DMAc solution of PVDF and lithium chloride obtained in step (3) was uniformly coated on the glass surface using a film forming apparatus. Subsequently, the coated glass was slowly immersed in deionized water for 5 minutes to prepare a PVDF film while retaining the mixed solution of DMAc, deionized water, and lithium chloride.

[0074] (6) Separation step of the dipolar aprotic solvent and water: the mixed solution in step (6) is poured into a distillation flask, heated to 100° C., and the deionized water is evaporated to separate the dipolar aprotic solvent and the deionized water.

[0075] Testing and characterization: The regenerated cathode material was characterized by inductively coupled plasma mass spectrometry (ICP) analysis. At the same time, the regenerated cathode material was assembled into a button half-cell and the charge and discharge test was carried out under the test conditions of 2.8V-4.3V voltage range and 0.1C current density. The test results are as follows: Figure 4 shown.

[0076] Example 4

[0077] like Figure 1 As shown, the method for regenerating waste lithium batteries provided in this embodiment specifically includes the following steps:

[0078] (1) Disassembly and discharge: Use a charge and discharge tester to discharge the used lithium battery at a current of 1 A until the voltage drops to 2 V. Subsequently, the battery is placed in a glove box for disassembly, the positive electrode material strip is peeled off, and the positive electrode strip is rinsed twice with dimethyl carbonate (purity >99%) to remove the residual electrolyte on the surface.

[0079] (2) Solution preparation: 40 mL of 5-dimethylamino-2-methyl-5-oxopentanoate (PolarClean), 3 g of xylose, and 3 g of lithium sulfate were mixed at room temperature to prepare a solution, ensuring that the solutes were evenly dissolved.

[0080] (3) Solvothermal reaction: Weigh 2 g of the positive electrode tape treated in step (1), add it to the mixed solution prepared in step (2), and pour it into a reactor. Place the reactor in an oven and heat it to 80°C for 8 hours. After the reaction is completed, cool it to room temperature and centrifuge it at 9000 rpm for 5 minutes to separate the solution and solid product. Subsequently, dry the solid at 120°C for 12 hours and sieve it to obtain aluminum foil and positive electrode powder.

[0081] (4) Annealing: After weighing the regenerated precursor, lithium carbonate (purity >99%) was added at a ratio of 5% and evenly ground in a mortar. The mixture was then poured into a porcelain boat and heated in a tube furnace at 850°C for 4 hours. After cooling, the regenerated positive electrode powder was obtained.

[0082] (5) Binder Regeneration Step: Using a film forming apparatus, the PolarClean solution of PVDF and lithium chloride obtained in step (3) was evenly coated on the glass surface. Subsequently, the coated glass was slowly immersed in deionized water for 5 minutes to form a PVDF film while retaining the mixed solution of PolarClean, deionized water, and lithium chloride.

[0083] (6) Separation step of the dipolar aprotic solvent and water: the mixed solution in step (6) is poured into a distillation flask, heated to 100° C., and the deionized water is evaporated to separate the dipolar aprotic solvent and the deionized water.

[0084] Testing and characterization: The regenerated cathode material was characterized by inductively coupled plasma mass spectrometry (ICP) analysis. At the same time, the regenerated cathode material was assembled into a button half-cell and the charge and discharge test was carried out under the test conditions of 2.8V-4.3V voltage range and 0.1C current density. The test results are as follows: Figure 5 shown.

[0085] Example 5

[0086] like Figure 1 As shown, the method for regenerating waste lithium batteries provided in this embodiment specifically includes the following steps:

[0087] (1) Disassembly and discharge: Use a charge and discharge tester to discharge the used lithium battery at a current of 1 A until the voltage drops to 2 V. Subsequently, the battery is placed in a glove box for disassembly, the positive electrode material strip is peeled off, and the positive electrode strip is rinsed twice with dimethyl carbonate (purity >99%) to remove the residual electrolyte on the surface.

[0088] (2) Solution preparation: 40 mL of triethyl citrate (TEC), 3 g of erythrose, and 3 g of lithium chloride were mixed at room temperature to prepare a solution, ensuring that the solutes were evenly dissolved.

[0089] (3) Solvothermal reaction: Weigh 2 g of the positive electrode tape treated in step (1), add it to the mixed solution prepared in step (2), and pour it into a reactor. Place the reactor in an oven and heat it to 80°C for 8 hours. After the reaction is completed, cool it to room temperature and centrifuge it at 9000 rpm for 5 minutes to separate the solution and solid product. Subsequently, dry the solid at 120°C for 12 hours and sieve it to obtain aluminum foil and positive electrode powder.

[0090] (4) Annealing: After weighing the regenerated precursor, lithium carbonate (purity >99%) was added at a ratio of 5% and evenly ground in a mortar. The mixture was then poured into a porcelain boat and heated in a tube furnace at 850°C for 4 hours. After cooling, the regenerated positive electrode powder was obtained.

[0091] (5) Binder regeneration step: The TEC solution of PVDF and lithium chloride obtained in step (3) was evenly coated on the glass surface using a film forming apparatus. Subsequently, the coated glass was slowly immersed in deionized water for 5 minutes to form a PVDF film while retaining the mixed solution of TEC, deionized water, and lithium chloride.

[0092] (6) Separation step of the dipolar aprotic solvent and water: the mixed solution in step (6) is poured into a distillation flask, heated to 100° C., and the deionized water is evaporated to separate the dipolar aprotic solvent and the deionized water.

[0093] Testing and characterization: The regenerated cathode material was characterized by inductively coupled plasma mass spectrometry (ICP) analysis. At the same time, the regenerated cathode material was assembled into a button half-cell and the charge and discharge test was carried out under the test conditions of 2.8V-4.3V voltage range and 0.1C current density. The test results are as follows: Figure 6 shown.

[0094] Example 6

[0095] like Figure 1 As shown, the method for regenerating waste lithium batteries provided in this embodiment specifically includes the following steps:

[0096] (1) Disassembly and discharge: Use a charge and discharge tester to discharge the used lithium battery at a current of 1 A until the voltage drops to 2 V. Subsequently, the battery is placed in a glove box for disassembly, the positive electrode material strip is peeled off, and the positive electrode strip is rinsed twice with dimethyl carbonate (purity >99%) to remove the residual electrolyte on the surface.

[0097] (2) Solution preparation: 40 mL of tetrabutyl succinamide (TBSA), 3 g of glucose, and 3 g of lithium chloride were mixed at room temperature to prepare a solution, ensuring that the solutes were uniformly dissolved.

[0098] (3) Solvothermal reaction: Weigh 2 g of the positive electrode tape treated in step (1), add it to the mixed solution prepared in step (2), and pour it into a reactor. Place the reactor in an oven and heat it to 80°C for 8 hours. After the reaction is completed, cool it to room temperature and centrifuge it at 9000 rpm for 5 minutes to separate the solution and solid product. Subsequently, dry the solid at 120°C for 12 hours and sieve it to obtain aluminum foil and positive electrode powder.

[0099] (4) Testing and Characterization: The regenerated cathode materials were subjected to various characterizations, including scanning electron microscopy (SEM) and inductively coupled plasma mass spectrometry (ICP) analysis. Furthermore, button-type half-cells were assembled using the regenerated cathode materials and subjected to charge and discharge tests. The test conditions were a voltage range of 2.8V-4.3V and a current density of 0.1C.

[0100] (5) Binder Regeneration Step: The TBSA solution of PVDF and lithium chloride obtained in step (3) was uniformly coated on the glass surface using a film forming apparatus. Subsequently, the coated glass was slowly immersed in deionized water for 5 minutes to form a PVDF film while retaining the mixed solution of TBSA, deionized water, and lithium chloride.

[0101] (6) Separation step of the dipolar aprotic solvent and water: the mixed solution in step (6) is poured into a distillation flask, heated to 100° C., and the deionized water is evaporated to separate the dipolar aprotic solvent and the deionized water.

[0102] Testing and characterization: The regenerated cathode material was characterized by inductively coupled plasma mass spectrometry (ICP) analysis. At the same time, the regenerated cathode material was assembled into a button half-cell and the charge and discharge test was carried out under the test conditions of 2.8V-4.3V voltage range and 0.1C current density. The test results are as follows: Figure 7 shown.

[0103] Example 7

[0104] like Figure 1 As shown, the method for regenerating waste lithium batteries provided in this embodiment specifically includes the following steps:

[0105] (1) Disassembly and discharge: Use a charge and discharge tester to discharge the used lithium battery at a current of 1 A until the voltage drops to 2 V. Subsequently, the battery is placed in a glove box for disassembly, the positive electrode material strip is peeled off, and the positive electrode strip is rinsed twice with dimethyl carbonate (purity >99%) to remove the residual electrolyte on the surface.

[0106] (2) Solution preparation: 40 mL of dimethyl sulfoxide (DMSO), 10 mL of paraformaldehyde (PF), 1 g of cellulose, and 3 g of lithium chloride (PF was added in this example to increase the solubility of cellulose in DMSO) were mixed at room temperature to prepare a solution, ensuring that the solutes were uniformly dissolved.

[0107] (3) Solvothermal reaction: Weigh 2 g of the positive electrode tape treated in step (1), add it to the mixed solution prepared in step (2), and pour it into a reactor. Place the reactor in an oven and heat it to 80°C for 8 hours. After the reaction is completed, cool it to room temperature and centrifuge it at 9000 rpm for 5 minutes to separate the solution and solid product. Subsequently, dry the solid at 120°C for 12 hours and sieve it to obtain aluminum foil and positive electrode powder.

[0108] (4) Annealing: After weighing the regenerated precursor, lithium carbonate (purity >99%) was added at a ratio of 5% and evenly ground in a mortar. The mixture was then poured into a porcelain boat and heated in a tube furnace at 850°C for 4 hours. After cooling, the regenerated positive electrode powder was obtained.

[0109] (5) Binder regeneration step: Using a film forming apparatus, the DMSO solution of PVDF and lithium chloride obtained in step (3) was uniformly coated on the glass surface. Subsequently, the coated glass was slowly immersed in deionized water for 5 minutes to prepare a PVDF film while retaining the mixed solution of DMSO, deionized water, and lithium chloride.

[0110] (6) Separation step of the dipolar aprotic solvent and water: the mixed solution in step (6) is poured into a distillation flask, heated to 100° C., and the deionized water is evaporated to separate the dipolar aprotic solvent and the deionized water.

[0111] Testing and characterization: The regenerated cathode material was characterized by inductively coupled plasma mass spectrometry (ICP) analysis. At the same time, the regenerated cathode material was assembled into a button half-cell and the charge and discharge test was carried out under the test conditions of 2.8V-4.3V voltage range and 0.1C current density. The test results are as follows: Figure 8 shown.

[0112] Figures 2 to 8The test results of the cycle performance of the recycled lithium battery positive electrode material and the retired lithium battery positive electrode material at a current density of 0.1C in Examples 1 to 7 are respectively shown. During the test, the charge and discharge voltage range was set to 2.8V to 4.3V. The data show that compared with the waste lithium battery, the discharge specific capacity of the recycled positive electrode material is significantly improved, and its cycle stability is also significantly enhanced. This shows that the direct repair and regeneration method for retired lithium-ion batteries adopted in the present invention can effectively restore the electrochemical properties of the retired lithium battery positive electrode material, and even make its performance close to the level of new batteries, which fully verifies the effectiveness and practicality of the regeneration technology.

[0113] Table 1 shows the inductively coupled plasma mass spectrometry (ICP) characterization data of the regenerated ternary lithium materials obtained in Examples 1-7, showing the inductively coupled plasma mass spectrometry (ICP) characterization data of the regenerated ternary lithium materials obtained by the direct repair and regeneration method of retired lithium-ion batteries without pre-separation.

[0114] Table 1 Inductively coupled plasma mass spectrometry (ICP) characterization data of the regenerated ternary lithium materials obtained in Examples 1-7

[0115] <![CDATA[ 实施例 / 元素 ]]> Li (wt%) Mn (wt%) Co (wt%) Ni (wt%) Al (wt%) Example 1 5.9306 12.7322 9.3731 23.4679 0.0504 Example 2 5.9039 12.8076 9.3661 23.3498 0.0515 Example 3 5.8524 12.9239 9.3955 23.5110 0.0516 Example 4 5.4218 12.0707 8.7344 21.8202 0.0367 Example 5 5.5139 11.9437 8.5647 21.5650 0.0368 Example 6 5.5605 12.1679 8.7670 22.0552 0.0373 Example 7 6.6129 14.9632 10.9736 27.5187 0.0532

[0116] The results show that the present invention can effectively achieve efficient separation of aluminum foil, binder, and positive electrode material. The separation efficiency of aluminum foil is particularly remarkable, and the aluminum content in the regenerated positive electrode material is extremely low, ensuring the purity of the positive electrode material. This demonstrates that the direct regeneration method for retired lithium-ion batteries without pre-separation not only simplifies the recycling process of lithium battery positive electrode materials but also significantly improves separation efficiency, providing a strong technical foundation for the efficient regeneration of positive electrode materials.

[0117] The method provided by the present invention is energy-saving and environmentally friendly, can reduce energy consumption and the use of chemical reagents, and reduce the cost of waste liquid treatment and the impact on the environment; the method provided by the present invention helps to improve the regeneration quality of materials, avoid damage to the material structure caused by multiple operations, and retain the original activity and performance of the materials; the method provided by the present invention can also improve economic benefits, reduce resource waste, and achieve efficient recycling of materials.

[0118] The above embodiments are only used to illustrate the inventive concept of the present invention, and are not intended to limit the protection of the rights of the present invention. Any simple modifications, equivalent changes, and modifications made to the above embodiments based on the essence of the technology and method of the present invention are still within the scope of the technology and method solutions of the present invention.

Claims

1. A method for directly repairing and regenerating retired lithium-ion batteries without pre-separation, characterized in that: The method comprises the following steps: (1) Discharge and disassembly: After the waste lithium-ion battery is fully discharged, it is disassembled and the positive electrode material strip is peeled off; (2) preparing a lithium source solution: mixing a lithium source, a reducing agent, and a dipolar aprotic solvent to prepare a lithium source solution; The lithium source solution includes N-methylpyrrolidone, glucose and lithium chloride; Alternatively, the lithium source solution comprises dimethyl sulfoxide, erythritol and lithium hydroxide; Or, the lithium source solution includes triethyl citrate, erythrose and lithium chloride; Alternatively, the lithium source solution comprises tetrabutylsuccinamide, glucose and lithium chloride; (3) Solvothermal reaction: The positive electrode material strip is mixed with the lithium source solution and heated at 60-80°C for reaction. After the reaction is completed, a mixed solution containing the lithium source, dipolar aprotic solvent and binder is obtained by centrifugation and sieving, and the precursor and current collector are regenerated; (4) Annealing: The regenerated precursor is mixed with lithium carbonate and then calcined to obtain a regenerated lithium battery positive electrode material.

2. The method for direct repair and regeneration of retired lithium-ion batteries without pre-separation according to claim 1, characterized in that: The regeneration method includes adhesive regeneration: coating the mixed solution prepared in step (3) on the glass surface and slowly immersing it in water to prepare an adhesive film and a mixed solution of a dipolar aprotic solvent and water.

3. The method for direct repair and regeneration of retired lithium-ion batteries without pre-separation according to claim 2, characterized in that: The regeneration method includes separating the solvent from water: using a fractionating column to separate the mixed solution of the dipolar aprotic solvent and water, and utilizing the difference in boiling points between the dipolar aprotic solvent and water to respectively recover pure dipolar aprotic solvent and water.

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