Method for directly repairing and regenerating retired lithium ion battery without pre-separation

Abstract

The invention discloses a pre-separation-free method for directly repairing and regenerating a retired lithium ion battery, which comprises the following steps of: after completely discharging a waste lithium ion battery, disassembling and stripping a positive electrode material belt; mixing a lithium source, a reducing agent and a dipole aprotic solvent to prepare a lithium source solution; mixing the positive electrode material strip with a lithium source solution, carrying out heating reaction at 60-100 DEG C, and after the reaction is finished, carrying out centrifugation and screening to obtain a mixed solution containing a lithium source, a dipole aprotic solvent and a binder, a regenerated precursor and a current collector; and mixing the regenerated precursor with lithium carbonate, and calcining to obtain the regenerated lithium battery positive electrode material. The method provided by the invention can realize 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 separation of pretreatment and regeneration processes in a 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 pre-separation. Background Art

[0002] The current global energy landscape is transforming from traditional fossil energy to clean and efficient energy. Renewable energy represented by photovoltaic and wind power has accelerated the development of new energy storage technologies due to its intermittent and unstable nature. In 2023, the total output of lithium batteries in China will reach 940GWh, and the total output value of the industry will exceed 1.4 trillion yuan, ranking first in the world. The main applications of lithium batteries are concentrated in new energy electric vehicles (domestic production and sales in 2023 will be 9.5 million vehicles, and exports will reach 1.2 million vehicles, both of which are the world's first) and electrochemical energy storage power stations (as of the end of 2023, a total of 1,375 stations have been built nationwide with a total installed capacity of 45.43GW).

[0003] With the large-scale application of lithium batteries, the peak of their retirement is also coming. The calendar life of power lithium batteries is about 10 years, of which the service life of non-operating private cars is generally 8 years or 150,000 kilometers, and that of operating vehicles is 6 years or 600,000 kilometers. The design life of energy storage lithium batteries requires that the number of cycles is greater than 3,500 times, but due to their high-frequency charging and discharging working characteristics, the actual design life of energy storage power stations is 8 to 10 years. At present, China is ushering in the peak of concentrated retirement of the first batch of power and energy storage lithium batteries. In 2023, the cumulative amount of retired lithium batteries will reach 590,000 tons, and the market size will reach 40 billion yuan. It is estimated that by 2030, the market size of retired lithium batteries will grow to 150 billion yuan.

[0004] The positive electrode materials of lithium batteries are mainly inorganic compounds containing a large amount of valuable metal elements, such as lithium manganese oxide, lithium cobalt oxide, nickel cobalt manganese oxide, and lithium iron phosphate. At present, the prices of various positive electrode materials are relatively high, with the price of ternary lithium being 110,000 yuan / ton, the price of lithium cobalt oxide being 150,000 yuan / ton, the price of lithium manganese oxide being 34,000 yuan / ton, and the price of lithium iron phosphate being 34,500 yuan / ton. In ternary lithium batteries, the cost of positive electrode materials accounts for 57% of the total battery cost, and in lithium iron phosphate batteries, the cost of positive electrode materials accounts for 40% of the total battery cost. It can be seen that positive electrode materials are the most valuable part of waste lithium batteries for recycling. The recycling technology of waste lithium-ion batteries focuses on recovering valuable metals in positive electrode materials. At present, the recycling methods of waste lithium-ion batteries mainly include: hydrometallurgy and pyrometallurgy.

[0005] The pyrometallurgical process uses high temperatures to extract and purify metals from spent lithium-ion batteries. It is a complex process involving multiple steps, including 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 remaining impurities and obtain pure metal. Finally, during refining, the metal is further purified by various techniques, such as electrolysis or distillation.

[0006] As a low-temperature processing technology, hydrometallurgy is widely used in the refining of metal ores and the recycling of secondary resources such as waste lithium-ion batteries. The core of this process is to effectively extract valuable metals from ores or concentrates through acid or alkali leaching, and then convert the leached solution into high-purity cathode material precursors using preparation methods such as coprecipitation or sol-gel method.

[0007] Different from hydrometallurgy and pyrometallurgy, direct regeneration technology focuses on the attenuation 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 discharge. Compared with the original form, the structure and composition of the cathode material have changed significantly after a long period of electrochemical cycling. These changes are mainly attributed to the loss of Li+ inside the lattice, the leaching of transition metal elements, and the formation of cracks on the surface of the material. The direct regeneration process can effectively supplement 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 certain concentration of lithium source solution, loads it into a high-pressure reactor, heats it at a certain temperature and pressure, and then anneals it to obtain a regenerated cathode material.

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

[0009] 1. The process is complex and has many steps: Since separation and regeneration are independent steps, additional equipment and processes are required to process the materials. The separation process in the process usually includes discharge, crushing, screening, solvent soaking and other links, and each step will increase time and cost. The multi-step process brings the complexity of coordination and management, and the conditions of each step need to be strictly controlled, which increases production costs and technical difficulties.

[0010] 2. High energy and resource consumption: Multi-step operation means that each step requires independent energy input (such as heating, solvent treatment, evaporation). Chemical solvents (such as NMP) in the separation process have high costs and require additional waste liquid treatment, increasing the risk of environmental pollution. Each step of the reaction in the step-by-step process takes a long time, increasing the overall recovery cycle and resulting in high energy consumption.

[0011] 3. High risk of material loss and contamination: During the independent pre-separation process, the binder (such as PVDF) may degrade or cannot be recycled, resulting in a waste of resources. Aluminum foil is easily damaged by the physical or chemical separation process, losing its recycling value or being contaminated, thereby reducing its reuse efficiency.

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

[0013] 5. Poor economic benefits: Since traditional methods can only partially recycle certain components in lithium batteries (such as binder PVDF or positive electrode materials), the overall recovery rate of materials 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] At present, there is no patent that realizes the combination of pre-separation and hydrothermal reaction process. For example, Chinese patent publication number CN118676464A only involves the use of asphalt as a reducing agent to regenerate positive electrode materials; in addition, CN111100324A discloses a method for recycling PVDF, a binder for waste lithium batteries, which includes soaking and dissolving the deep-discharged and crushed waste battery cells in an organic solvent N-methylpyrrolidone (NMP), and then filtering and distilling under reduced pressure to obtain the binder PVDF. This method only achieves the separation of the positive electrode material and the binder, and cannot simultaneously complete the regeneration of the positive electrode material.

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

[0016] The present invention aims to provide a direct repair and regeneration method for retired lithium-ion batteries without pre-separation. The method is based on the principle of solvothermal reaction and uses a reducing solvent system of a dipole aprotic solvent, a lithium salt and a green reducing agent. The method can achieve the repair and regeneration of the positive electrode material while separating the positive electrode material, the binder and the current collector. The present invention overcomes the complex operation problem of separating the pretreatment and regeneration process in the traditional hydrothermal regeneration process and simplifies 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) Discharging and disassembling: After the waste lithium-ion battery is completely 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, the dipolar aprotic solvent and the binder is obtained by centrifugation and sieving, and the precursor and the 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, annealing and other steps.

[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, the positive electrode strip is treated with lithium supplement and the binder is removed using a mixed solution containing a lithium source, a reducing agent and a dipolar aprotic solvent; and then after a short period of annealing treatment, the material structure is repaired to obtain 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-oxopentanoic acid methyl ester (PolarClean), acetylcitrate triethyl (ATEC), dibutyl phthalate (DBP), dibutyl sebacate (DBS), diethyl phthalate (DEP), hexamethylphosphoric acid triamide (HMPA), triethyl citrate (TEC), triacetin, trimethyl phosphate (TMP) or tetrabutylsuccinamide (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 obtain a binder film (PVDF film) and a mixed solution of the dipolar aprotic solvent and water.

[0030] Furthermore, the method also includes: (6) separation of solvent and water: using a distillation 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] Further, the dipolar aprotic solvent is selected from N-methylpyrrolidone, dimethyl sulfoxide, triethyl citrate, tetrabutyl succinamide, dimethylacetamide or dimethylamino-2-methyl-5-oxopentanoic acid methyl ester, 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. The present invention controls the type of lithium source solution to achieve efficient separation and regeneration of the positive electrode material and the current collector, while enabling the regenerated lithium battery to have higher capacity and cycle stability.

[0032] Further preferably, the dipolar aprotic solvent is selected from one of 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. The present invention further optimizes the type of lithium source solution to enable the regenerated lithium battery to have higher capacity and cycle stability.

[0033] The present invention not only effectively realizes the recycling of waste lithium batteries and avoids waste of resources, but also the reagents used can be recycled, meeting the requirements of green environmental protection. In addition, the introduction of dipolar aprotic solvent organically combines the pretreatment and regeneration processes, reduces the overall cost, and improves the efficiency of the regeneration process 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, thereby achieving efficient separation of the positive electrode material and the current collector.

[0036] (2) The present invention uses a specific solvent system, a dipolar aprotic solvent to dissolve the lithium source and the binder, and adopts a low-cost green reducing agent to reduce the energy barrier of the regeneration reaction, thereby realizing the combination of the pretreatment process and the regeneration process. The regeneration process of this reducing solvent thermal reaction system greatly reduces the operation steps and simplifies the entire process, thereby realizing the efficient regeneration of retired lithium-ion batteries.

[0037] (3) The reagents and materials in the entire process of the present invention can be recycled and reused. In this process, the binder, current collector, dipolar aprotic solvent, lithium source and positive electrode material can be effectively separated and used for subsequent recovery and regeneration operations; the current collector maintains a complete structure, and there is no positive electrode material and binder residue on the surface; the structure of the binder is not damaged and can be used normally; the dipolar aprotic solvent is separated from water by fractionation technology to ensure recycling.

[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, with 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 cycle performance of the regenerated 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 cycle performance of the regenerated 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 cycle performance of the regenerated 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 cycle performance of the regenerated ternary lithium material obtained in Example 4 and the waste ternary lithium material 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 cycle performance of the regenerated ternary lithium material obtained in Example 5 and the waste ternary lithium material 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 cycle performance of the regenerated 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 cycle performance of the regenerated ternary lithium material obtained in Example 7 and the waste ternary lithium material 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 comprises the following steps:

[0051] (1) Disassembly and discharge: Use a charge and discharge tester to discharge the waste lithium battery at a current of 1 A until the voltage drops to 2 V. Then, place the battery in a glove box for disassembly, peel off the positive electrode material strip, and rinse the positive electrode strip 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 obtain aluminum foil and positive electrode powder by sieving.

[0054] (4) Annealing: After weighing the regenerated precursor, add lithium carbonate (purity>99%) at a ratio of 5%, grind and mix evenly in a mortar. Then pour the mixture into a porcelain boat and heat it in a tube furnace at 850°C for 4 hours. After cooling, the regenerated positive electrode powder is obtained.

[0055] (5) Binder regeneration step: The NMP solution of PVDF and lithium chloride obtained in step (3) is uniformly coated on the glass surface using a film forming apparatus. Subsequently, the coated glass is slowly immersed in deionized water for 5 minutes to prepare 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: Pour the mixed solution in step (6) into a distillation flask, heat it to 100° C., evaporate the deionized water, and 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. The test conditions were 2.8V-4.3V voltage range and current density of 0.1C. 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 comprises the following steps:

[0060] (1) Disassembly and discharge: Use a charge and discharge tester to discharge the waste lithium battery at a current of 1 A until the voltage drops to 2 V. Then, place the battery in a glove box for disassembly, peel off the positive electrode material strip, and rinse the positive electrode strip 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 evenly 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 obtain aluminum foil and positive electrode powder by sieving.

[0063] (4) Annealing: After weighing the regenerated precursor, add lithium carbonate (purity>99%) at a ratio of 5%, grind and mix evenly in a mortar. Then pour the mixture into a porcelain boat and heat it in a tube furnace at 850°C for 4 hours. After cooling, the regenerated positive electrode powder is obtained.

[0064] (5) Binder regeneration step: The DMSO solution of PVDF and lithium chloride obtained in step (3) is uniformly coated on the glass surface using a film forming apparatus. Subsequently, the coated glass is 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: Pour the mixed solution in step (6) into a distillation flask, heat it to 100° C., evaporate the deionized water, and 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. The test conditions were 2.8V-4.3V voltage range and current density of 0.1C. 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 comprises the following steps:

[0069] (1) Disassembly and discharge: Use a charge and discharge tester to discharge the waste lithium battery at a current of 1 A until the voltage drops to 2 V. Then, place the battery in a glove box for disassembly, peel off the positive electrode material strip, and rinse the positive electrode strip 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 obtain aluminum foil and positive electrode powder by sieving.

[0072] (4) Annealing: After weighing the regenerated precursor, add lithium carbonate (purity>99%) at a ratio of 5%, grind and mix evenly in a mortar. Then pour the mixture into a porcelain boat and heat it in a tube furnace at 850°C for 4 hours. After cooling, the regenerated positive electrode powder is obtained.

[0073] (5) Binder regeneration step: The DMAc solution of PVDF and lithium chloride obtained in step (3) is uniformly coated on the glass surface using a film forming apparatus. Subsequently, the coated glass is 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: Pour the mixed solution in step (6) into a distillation flask, heat it to 100° C., evaporate the deionized water, and 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. The test conditions were 2.8V-4.3V voltage range and current density of 0.1C. 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 comprises the following steps:

[0078] (1) Disassembly and discharge: Use a charge and discharge tester to discharge the waste lithium battery at a current of 1 A until the voltage drops to 2 V. Then, place the battery in a glove box for disassembly, peel off the positive electrode material strip, and rinse the positive electrode strip 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-oxopentanoic acid methyl ester (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 obtain aluminum foil and positive electrode powder by sieving.

[0081] (4) Annealing: After weighing the regenerated precursor, add lithium carbonate (purity>99%) at a ratio of 5%, grind and mix evenly in a mortar. Then pour the mixture into a porcelain boat and heat it in a tube furnace at 850°C for 4 hours. After cooling, the regenerated positive electrode powder is obtained.

[0082] (5) Binder regeneration step: The PolarClean solution of PVDF and lithium chloride obtained in step (3) is uniformly coated on the glass surface using a film forming apparatus. Subsequently, the coated glass is slowly immersed in deionized water for 5 minutes to prepare 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: Pour the mixed solution in step (6) into a distillation flask, heat it to 100° C., evaporate the deionized water, and 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. The test conditions were 2.8V-4.3V voltage range and current density of 0.1C. 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 comprises the following steps:

[0087] (1) Disassembly and discharge: Use a charge and discharge tester to discharge the waste lithium battery at a current of 1 A until the voltage drops to 2 V. Then, place the battery in a glove box for disassembly, peel off the positive electrode material strip, and rinse the positive electrode strip 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 obtain aluminum foil and positive electrode powder by sieving.

[0090] (4) Annealing: After weighing the regenerated precursor, add lithium carbonate (purity>99%) at a ratio of 5%, grind and mix evenly in a mortar. Then pour the mixture into a porcelain boat and heat it in a tube furnace at 850°C for 4 hours. After cooling, the regenerated positive electrode powder is obtained.

[0091] (5) Binder regeneration step: The TEC solution of PVDF and lithium chloride obtained in step (3) is uniformly coated on the glass surface using a film forming apparatus. Subsequently, the coated glass is slowly immersed in deionized water for 5 minutes to prepare 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: Pour the mixed solution in step (6) into a distillation flask, heat it to 100° C., evaporate the deionized water, and 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. The test conditions were 2.8V-4.3V voltage range and current density of 0.1C. 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 comprises the following steps:

[0096] (1) Disassembly and discharge: Use a charge and discharge tester to discharge the waste lithium battery at a current of 1 A until the voltage drops to 2 V. Then, place the battery in a glove box for disassembly, peel off the positive electrode material strip, and rinse the positive electrode strip 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 obtain aluminum foil and positive electrode powder by sieving.

[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. At the same time, the regenerated cathode materials were assembled into button-type half-cells for 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) is uniformly coated on the glass surface using a film forming apparatus. Subsequently, the coated glass is slowly immersed in deionized water for 5 minutes to prepare 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: Pour the mixed solution in step (6) into a distillation flask, heat it to 100° C., evaporate the deionized water, and 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. The test conditions were 2.8V-4.3V voltage range and current density of 0.1C. 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 comprises the following steps:

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

[0106] (2) Preparation of solution: 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 to ensure 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 obtain aluminum foil and positive electrode powder by sieving.

[0108] (4) Annealing: After weighing the regenerated precursor, add lithium carbonate (purity>99%) at a ratio of 5%, grind and mix evenly in a mortar. Then pour the mixture into a porcelain boat and heat it in a tube furnace at 850°C for 4 hours. After cooling, the regenerated positive electrode powder is obtained.

[0109] (5) Binder regeneration step: The DMSO solution of PVDF and lithium chloride obtained in step (3) is uniformly coated on the glass surface using a film forming apparatus. Subsequently, the coated glass is 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: Pour the mixed solution in step (6) into a distillation flask, heat it to 100° C., evaporate the deionized water, and 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. The test conditions were 2.8V-4.3V voltage range and current density of 0.1C. The test results are as follows: Figure 8 shown.

[0112] Figures 2 to 8The test results of the cycle performance of the positive electrode materials of recycled lithium batteries and the positive electrode materials of retired lithium batteries 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 batteries, 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 of retired lithium-ion batteries adopted in the present invention can effectively restore the electrochemical properties of the positive electrode materials of retired lithium batteries, and even make their 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. In particular, the separation efficiency of aluminum foil is remarkable, and the aluminum content in the regenerated positive electrode material is extremely low, ensuring the purity of the positive electrode material. This shows that the direct repair and regeneration method of retired lithium-ion batteries without pre-separation not only simplifies the recycling process of lithium battery positive electrode materials, but also significantly improves the separation effect, providing a strong technical guarantee 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 explain the inventive concept of the present invention, rather than 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) Discharging and disassembling: After the waste lithium-ion battery is completely 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; (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, the dipolar aprotic solvent and the binder is obtained by centrifugation and sieving, and the precursor and the 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: In step (2), the dipolar aprotic solvent is selected from one or a combination of at least two of N-methylpyrrolidone, dimethyl sulfoxide, dimethylformamide, acetone, dimethylacetamide, 5-dimethylamino-2-methyl-5-oxopentanoic acid methyl ester, acetylcitrate triethyl, dibutyl phthalate, dibutyl sebacate, diethyl phthalate, hexamethylphosphoric acid triamide, triethyl citrate, triacetin, trimethyl phosphate or tetrabutylsuccinamide.

3. The method for direct repair and regeneration of retired lithium-ion batteries without pre-separation according to claim 1, characterized in that: 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 or lignin.

4. The method for direct repair and regeneration of retired lithium-ion batteries without pre-separation according to claim 1, characterized in that: 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 or lithium acetate.

5. 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 comprises the following steps: coating the mixed solution obtained in step (3) on the glass surface and slowly immersing the mixed solution in water to obtain a mixed solution of a binder film and a dipole aprotic solvent and water.

6. The method for direct repair and regeneration of retired lithium-ion batteries without pre-separation according to claim 5, characterized in that: The regeneration method comprises separation of solvent and water: using a fractionation column to separate a mixture of a 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.

7. The method for direct repair and regeneration of retired lithium-ion batteries without pre-separation according to any one of claims 1 to 6, characterized in that: The dipolar aprotic solvent is selected from N-methylpyrrolidone, dimethyl sulfoxide, triethyl citrate, tetrabutyl succinamide, dimethylacetamide or dimethylamino-2-methyl-5-oxopentanoic acid methyl ester, 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.

8. The method for direct repair and regeneration of retired lithium-ion batteries without pre-separation according to claim 7, characterized in that: The dipolar aprotic solvent is selected from one of 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.

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