All-component recovery processing method for waste lithium ion battery

Abstract

The invention belongs to the technical field of new energy battery recovery processing, and discloses a waste lithium ion battery full-component recovery processing method. The treatment method comprises the following steps: carrying out discharging and shell cutting treatment on the waste lithium ion battery to obtain a battery cell, and carrying out soaking treatment on the battery cell by adopting a leaching solvent to obtain a leaching solution and the battery cell without an electrolyte; carrying out reduced-pressure step-by-step distillation on the leachate for component separation, and recovering to obtain a solvent component and a lithium salt component; and disassembling the battery cell from which the electrolyte is removed into a positive pole piece, a negative pole piece and a diaphragm, and performing powder removal treatment on the positive pole piece and the negative pole piece respectively by adopting an eluent to obtain a positive current collector, a negative current collector, positive powder and negative powder. According to the method, the electrolyte in the battery cell is leached out by adopting the specific leaching solvent, so that the harm of hydrofluoric acid, an organic solvent and the like formed by the residual electrolyte to a human body and the environment in the subsequent fine disassembly process of the battery cell is avoided, and the full-component recovery of the waste retired battery is realized.

Description

Technical Field

[0001] This invention belongs to the field of new energy battery recycling technology, specifically relating to a method for recycling and processing all components of waste lithium-ion batteries. Background Technology

[0002] As the market for new energy batteries expands, the scale of retired batteries is also growing. Currently, research on the recycling and utilization of retired batteries focuses primarily on high-value-added cathode and anode materials, with relatively little research on electrolyte recycling. However, electrolyte is a crucial component of batteries, accounting for approximately 15% of their mass. Even after charge-discharge cycles during use, about 70% of the electrolyte remains in the battery cells after retirement. Current crushing processes mostly involve directly feeding the entire battery into a crusher for multi-stage shredding. To prevent the heat generated by short circuits between the positive and negative electrodes during shredding from igniting the battery, a large amount of inert gas is required for protection during the crushing process.

[0003] Currently, electrolytes are a major obstacle to the precise disassembly of batteries, and they are also the most dangerous component within a battery. The electrolyte in lithium-ion batteries is primarily composed of organic solvents and lithium hexafluorophosphate. While the organic solvents are inexpensive, some are hazardous chemicals, and their large quantities can easily volatilize and pollute the air, harming human health. Lithium hexafluorophosphate, a lithium salt, readily forms HF (fluorine phosphate) when exposed to air, also posing a health hazard. Lithium hexafluorophosphate contains up to 75% fluorine by mass, which decomposes slowly in air. Incomplete decomposition can leave residues in the positive and negative electrode materials, increasing corrosion of equipment during subsequent electrode processing. Therefore, fluoride protection for the equipment must be considered, significantly increasing equipment investment. Currently, the industrial treatment of spent lithium-ion battery electrolyte involves heating and evaporating followed by calcination and pyrolysis. The pyrolysis of organic solvents requires high-temperature calcination, which is energy-intensive. Furthermore, the electrolyte contains valuable components such as ethylene carbonate, propylene carbonate, and additives. Recycling and reusing the electrolyte would significantly increase the economic value of battery recycling. Removing the electrolyte from the battery cell allows for more precise disassembly, significantly improving the quality of the recovered positive and negative electrode materials. While some patents report on precise disassembly and harmless electrolyte treatment, using steps such as disassembly, negative pressure drying, crushing, sieving, and color sorting to recover battery casings, electrode powders, separator fragments, electrolyte, copper particles, and aluminum particles from spent lithium-ion batteries, achieving full component recovery, they do not consider the recovery of the electrolyte solute lithium hexafluorophosphate. Low-temperature evaporation cannot remove the electrolyte, and harmful lithium hexafluorophosphate enters subsequent processes, severely polluting the environment. In addition, a few patent reports use leaching solvents to leach and recover electrolytes, but the leaching solvents used are generally flammable, explosive or highly toxic solvents, posing a high safety hazard.

[0004] In summary, the following issues still exist regarding electrolyte recycling and battery dismantling:

[0005] (1) Currently, the recycling of electrolyte often involves first crushing the battery cell and then extracting the electrolyte, resulting in a large amount of copper and aluminum impurities in the recovered positive and negative electrode materials. The cost of removing impurities at the back end is high, and it is not possible to extract the electrolyte first and then disassemble the battery cell.

[0006] (2) Currently, regarding electrolyte recovery, the recovery process often leads to the decomposition of lithium hexafluorophosphate, and the recovery products are calcium fluoride and calcium phosphate, which cannot achieve the recycling of LiPF6 and result in resource waste.

[0007] (3) The solvents commonly used for electrolyte leaching are often flammable and explosive solvents, or have high toxicity and are unsafe.

[0008] (4) The supercritical CO2 extraction technology and low-temperature freezing and crushing technology currently used for electrolyte recycling are complex to operate, require expensive equipment, and have high costs for recycling electrolyte, making them unsuitable for industrial application. Summary of the Invention

[0009] To address the shortcomings and deficiencies of existing technologies, the present invention aims to provide a method for the complete recycling and processing of waste lithium-ion batteries. This invention overcomes the numerous drawbacks of existing waste lithium battery whole-cell crushing methods that do not remove the casing, including significant environmental impact, large amounts of acid and alkali used, excessive waste residue and wastewater, high processing costs, harsh crushing site environment, and the risk of dust explosions; furthermore, the difficulty in distinguishing between positive and negative electrode active materials and copper and aluminum foil fragments after crushing, grinding, and sorting, and the difficulty in extracting high-value rare metals.

[0010] The objective of this invention is achieved through the following technical solution:

[0011] A method for recycling and processing all components of waste lithium-ion batteries includes the following processing steps:

[0012] (1) After discharging and shell cutting of waste lithium-ion batteries, the complete cells are taken out and the cells are added to the leaching solvent for soaking treatment to obtain cells without electrolyte and leaching solution containing electrolyte.

[0013] (2) The electrolyte-containing leachate is separated into components by stepwise vacuum distillation to recover mixed solvent 1 and lithium salt component (product ⑧-lithium salt). The mixed solvent 1 is recycled as a leachate solvent directly or after adjustment.

[0014] (3) The electrolyte-free battery cell is disassembled into positive electrode plate, negative electrode plate and separator (product ⑥-separator) for separate processing and recycling.

[0015] Further, the discharge mentioned in step (1) refers to immersing the waste lithium-ion battery in a salt solution for discharge until the open circuit voltage drops below 1.5V; the salt solution refers to an aqueous solution with a mass concentration of 2wt% to 15wt% containing one or more salts such as sodium chloride, sodium sulfate, and ferric sulfate.

[0016] Furthermore, the shell-cutting process described in step (1) refers to cutting open the aluminum or stainless steel casing of the battery without damaging the internal battery cell, and completely removing the internal battery cell containing the electrolyte. This process allows for the recycling of the metal casing (product ① - casing).

[0017] Furthermore, the amount of leaching solvent added in step (1) is 1 to 5 times the volume of the battery cell. The immersion treatment can be carried out under normal temperature and static conditions. The above operation is simple and has low energy consumption. The immersion treatment time can be adjusted according to the actual situation. Generally, a good electrolyte leaching rate can be achieved after more than 48 hours. The preferred immersion treatment time is 2 to 10 days.

[0018] Furthermore, the leaching solvent comprises a first component and a second component;

[0019] The first component is selected from carbonates and / or carboxylic esters and / or ethers;

[0020] The second component is selected from nitrile compounds;

[0021] Based on the total mass of the leaching solvent, the mass ratio of the first component to the second component is 0.125 to 8.

[0022] Furthermore, the leaching solvent in step (1) also includes a third component, a fourth component, and a co-solvent;

[0023] Based on the total mass of the leaching solvent, the mass percentage of each component is as follows: Component 1 5%–40%, Component 2 5%–40%, Component 3 5%–20%, Component 4 10%–60%, and co-solvent 5%–40%.

[0024] The third component is a compound as shown in Formula I below;

[0025] R1 to R6 are the same or different fluorine substituents, ethoxy groups, fluorine-substituted methoxy groups, fluorine-substituted ethoxy groups, or phenoxy groups;

[0026] The fourth component is at least one of perfluorohexanone (perfluorohexacarbonone), perfluoroheptanone (perfluoroheptanone), perfluorooctanone (perfluorooctanone), and perfluorononanone (perfluorononanone).

[0027] Further, the first component is selected from one or more of dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, dipropyl carbonate, methyl formate, methyl acetate, ethyl formate, ethyl acetate, methyl propionate, ethyl propionate, propyl acetate, propyl propionate, butyl propionate, propyl butyrate, butyl butyrate, diethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, ethyl monofluoroacetate, ethyl trifluoroacetate, butyl trifluoroacetate, trifluoroethyl butyrate, methyl trifluoroethyl carbonate, and dimethyl sulfite.

[0028] Furthermore, the second component is selected from one or more mixtures of acetonitrile, propionitrile, butyronitrile, fluoroacetonitrile, and chloroacetonitrile.

[0029] Furthermore, the co-solvent is selected from one or more of anhydrous ethanol, propanol, acetone, butanone, and isopropanol.

[0030] The third component used in this invention primarily achieves flame retardancy of the leaching solvent by capturing active free radicals such as H·, O·, and HO· that sustain combustion during the process, thereby terminating the chain reaction and improving the safety of the leaching solvent during use. Since excessive leaching solvent residue in the battery cell must be avoided after leaching, the subsequent drying of the battery cell needs to be considered. Therefore, all solvents used in the leaching solution are low-boiling-point, volatile solvents. However, in the flame retardancy of low-boiling-point flammable solvents, relying solely on the third component cannot achieve vapor flame retardancy on the liquid-gas surface of the leaching solvent, and thus cannot achieve effective flame retardancy. However, by further using a fourth component, flame retardancy can be achieved. The fourth component has a lower boiling point and can form a non-flammable vapor protective layer on the liquid surface of the leaching solution, thereby avoiding combustion and explosion problems caused by the volatilization of flammable solvents on the surface of the leaching solution during use.

[0031] Further, the first component is selected from one or more mixtures of dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, dipropyl carbonate, methyl formate, methyl acetate, ethyl formate, ethyl acetate, methyl propionate, ethyl propionate, propyl acetate, propyl propionate, butyl propionate, propyl butyrate, butyl butyrate, diethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, ethyl monofluoroacetate, ethyl trifluoroacetate, butyl trifluoroacetate, trifluoroethyl n-butyrate, methyl trifluoroethyl carbonate, and dimethyl sulfite. The first component used in this invention has high solubility for lithium hexafluorophosphate and mainly functions to dissolve residual lithium hexafluorophosphate in the overall leachate, effectively leaching out solid lithium hexafluorophosphate remaining inside the battery cell and in the pores of the electrode material.

[0032] Furthermore, the second component is selected from one or more of acetonitrile, propionitrile, butyronitrile, fluoroacetonitrile, and chloroacetonitrile. The second component used in this invention has a high dielectric constant, thus improving the dielectric constant of the leaching agent. Because the electrolyte remaining in retired lithium-ion batteries has a high water content, and the water content during solvent leaching of the electrolyte is much higher than that of the electrolyte itself, lithium hexafluorophosphate is prone to decomposition in a high-water-content environment. Introducing a solvent with a high dielectric constant can effectively improve the dielectric constant of the leaching agent. + The proportion of solvated structures ensures that lithium hexafluorophosphate exists in the leachate as solvated molecules, thus avoiding the reaction between lithium hexafluorophosphate molecules and water molecules.

[0033] Furthermore, the co-solvent is selected from one or more of anhydrous ethanol, propanol, acetone, butanone, and isopropanol. Because the fourth component used in this invention is almost immiscible with the first and second components (carbonates, carboxylic esters, etc.) that dissolve lithium hexafluorophosphate, the co-solvent greatly increases the solubility of the fourth component in the first and second components, ensuring that the fourth component is uniformly dispersed in the leaching solution, thereby exerting its excellent flame-retardant effect and achieving a non-flammable level in the leaching solution.

[0034] Further, the specific steps for component separation by stepwise vacuum distillation in step (2) are as follows: first, the mixture is kept under vacuum of 500-10000 Pa and temperature of 10-50℃ for 5-48 hours, and the mixed solvent 1 is recovered by distillation; the remaining solution is kept under vacuum of 500-10000 Pa and temperature of 50-90℃ for 5-48 hours, and the mixed solvent 2 (product ⑦-high boiling point solvent) and the lithium salt are recovered by distillation; wherein the boiling point of the mixed solvent 1 is lower than that of the mixed solvent 2.

[0035] If a one-step vacuum distillation is used to recover lithium salt components (lithium hexafluorophosphate), high-boiling-point solvents such as propylene carbonate (PC) and ethylene carbonate (EC) in the electrolyte will be introduced into the solvent, which is not conducive to their reuse in the leaching solvent system.

[0036] The components of the mixed solvent 1 mainly include leaching solvent components and low-boiling-point organic solvent components (such as dimethyl carbonate DMC) in the leaching electrolyte, which can be recycled as a leaching solvent or used to prepare new leaching solvents; the components of the mixed solvent 2 mainly include high-boiling-point organic solvent components in the leaching electrolyte, which can be further separated by distillation or directly applied to the preparation of electrolyte.

[0037] Furthermore, the positive electrode sheet obtained in step (3) is further processed and recycled using the following method:

[0038] The positive electrode sheet is immersed in eluent 1 to dissolve the positive electrode binder and perform de-powdering treatment to obtain a positive electrode current collector (product ③ - positive electrode current collector) and de-powdering solution 1. The de-powdering solution 1 is filtered and the solid phase is dried to obtain positive electrode powder (product ② - positive electrode powder). The eluent 1 includes one or more solvents selected from N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO). The de-powdering treatment refers to standing de-powdering treatment at a temperature of 50-150℃ for 5-24 hours.

[0039] Furthermore, the negative electrode sheet obtained in step (3) is further processed and recycled using the following method:

[0040] The negative electrode sheet is immersed in eluent 2 to dissolve the negative electrode binder and perform de-powdering treatment to obtain a negative electrode current collector (product ⑤ - negative electrode current collector) and de-powdering solution 2. The de-powdering solution 2 is filtered and the solid phase is dried to obtain negative electrode powder (product ④ - negative electrode powder). The eluent 2 includes a mixture of one or more solvents such as deionized water, ethanol and acetone. The de-powdering treatment refers to standing de-powdering treatment at room temperature for 5 to 24 hours.

[0041] Compared with the prior art, the beneficial effects of the present invention are:

[0042] (1) The processing method of the present invention can recycle the electrolyte of waste lithium-ion batteries, extracting the electrolyte from the battery cell without damaging the cell, so that the cell can be safely disassembled for further fine processing, thereby achieving full-component recycling of waste retired batteries. This method is simple and easy to implement, suitable for industrial production, improves the purity of each component in the recycled retired batteries, has low impurity content, high recovery rate, and is environmentally friendly.

[0043] (2) The processing method of the present invention overcomes the shortcomings of existing waste lithium battery whole crushing treatment methods that do not remove the casing, such as large environmental impact, large amount of acid and alkali consumption, large amount of waste residue and wastewater, high treatment cost, harsh crushing site environment, dust explosion accident; after crushing, grinding and sorting, positive and negative electrode active materials and copper and aluminum foil fragments are mixed and difficult to distinguish, and high-value rare metals are difficult to extract. It only requires immersing the battery cell in the leachate solvent for static soaking treatment, without additional electricity, manpower, gas and other losses, and the overall production cost is low.

[0044] (3) The second component solvent used in this invention has a high dielectric constant, which plays a role in improving the dielectric constant of the leaching agent. Since the electrolyte of retired lithium-ion batteries has a high water content, and the water content will be much higher than that of the electrolyte during the solvent leaching process, lithium hexafluorophosphate is prone to decomposition in an environment with high water content. When a second component solvent with a high dielectric constant is introduced, the proportion of Li+ solvated structure can be effectively increased, ensuring that lithium hexafluorophosphate exists in the leaching solution in the form of solvated molecules, thus avoiding the reaction between lithium hexafluorophosphate molecules and water molecules.

[0045] (4) The preferred leaching solvent used in this invention achieves flame retardancy through the combined use of a third component, a fourth component, and a co-solvent. The third component primarily terminates the chain reaction by capturing active free radicals such as H·, O·, and HO· that sustain combustion during the process. The fourth component forms a non-flammable vapor protective layer on the liquid surface of the leachate, achieving vapor flame retardancy on the liquid-gas surface of the leachate. Simultaneously, the co-solvent significantly increases the solubility of the fourth component in the first and second components, ensuring uniform dispersion of the fourth component in the leachate solution and thus maximizing its flame retardant effect. Through the synergistic effect of these three components, flame retardancy of the volatile solvent is achieved, giving the leachate a high flash point or even no flash point, greatly ensuring the safety of the leaching solvent during large-scale use.

[0046] (5) The solvent selected for the leaching solvent of the present invention is a low-boiling-point solvent, which can ensure the rapid drying of the battery cell after soaking in the leaching solution, and is also conducive to dissolving the electrolyte in the leaching solution. It can be used to quickly separate the high-boiling-point solvent in the leaching solution and the electrolyte by distillation, so that the leaching solvent can be easily recycled; and LiPF6 can be recovered by distillation below the decomposition temperature of LiPF6.

[0047] (6) By controlling the content range of the first component and the flame retardant solvent, the leaching solvent of the present invention can simultaneously achieve good lithium salt leaching rate and flame retardant effect. Attached Figure Description

[0048] Figure 1 This is a process flow diagram of the whole-component recycling and treatment method for waste lithium-ion batteries in the embodiment.

[0049] Figure 2 This is a diagram of the cylindrical battery cell after being immersed in electrolyte in the embodiment.

[0050] Figure 3 This is a diagram of a square battery cell after being immersed in electrolyte, as shown in the example.

[0051] Figure 4 The XRD pattern of the recovered cathode powder in Case 1 is shown.

[0052] Figure 5 The image shows the ion chromatography analysis results of the leachate in Case 1 for comparison. Detailed Implementation

[0053] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0054] The preparation method of the leaching solvent in the following examples is as follows:

[0055] Preparation of esters / ethers + nitriles: Weigh out the carbonate / carboxylic acid ester / ether solvent and the nitrile solvent with high dielectric constant according to the mass ratio, and stir until the solution is uniformly mixed.

[0056] Preparation of esters + nitriles + flame retardants…: Weigh out the carbonate / carboxylic acid ester / ether solvent, the high dielectric constant nitrile solvent, flame retardant component one, flame retardant component two and co-solvent according to the mass ratio, stir until the solution is uniformly mixed without layering.

[0057] The process flow diagram of the whole-component recycling and treatment method of waste lithium-ion batteries in the following embodiments is shown below. Figure 1 As shown.

[0058] The residual electrolyte composition of the 32650 cylindrical lithium iron phosphate batteries processed in the following examples, analyzed by ion chromatography and gas chromatography, was as follows: LiPF6 (13.1%), EC (ethylene carbonate, 32.0%), DMC (dimethyl carbonate, 21.9%), EMC (ethyl methyl carbonate, 28.8%), and PC (propylene carbonate, 4.2%). All percentages in parentheses refer to mass percentages. The average residual electrolyte in a single battery was 16g. The volume of a single cell was approximately 52mL. (The cell is described as follows...) Figure 2 As shown.

[0059] The following examples show a square aluminum-cased battery, model number LFP23140160-55Ah. Analysis of the residual electrolyte composition in the battery cell using ion chromatography and gas chromatography revealed the following: LiPF6 (12.9%), EC (25%), DMC (27.9%), EMC (29.5%), and PC (4.7%). All percentages in parentheses refer to mass percentages. The average residual electrolyte in a single battery was 193.8g. The volume of a single battery cell was approximately 525mL. (The cell is described in the original text.) Figure 3 As shown.

[0060] The instruments involved in the testing mainly include: IC ion chromatograph (930 Compact IC flex), GC gas chromatograph (Agilent 7890B), ICP-OES (Agilent 5110), and XRD (MiniFlex600).

[0061] The LiPF6 recovery rate is calculated as follows: Recovery rate = (actual recovered mass m) / ((theoretical recovered mass per cell M) × (number of cells n)).

[0062] Example 1:

[0063] In this embodiment, the leaching solvent used is: DMC (60% by mass) + acetonitrile (40% by mass); the 32650 cylindrical lithium iron phosphate battery treated in this embodiment.

[0064] The specific recycling and processing steps are as follows:

[0065] Step (1): Discharge, immerse the retired battery in a 10% sodium sulfate aqueous solution for 24 hours, dry the surface of the battery casing, and test its open circuit voltage to be 0.6V (below 1.5V).

[0066] Step (2): Cut the casing. Use the MSK-530 cylindrical battery casing remover to cut the battery casing and remove the complete battery cell containing a large amount of electrolyte. This process can realize the recycling of the metal casing.

[0067] Step (3): Arrange the 5 battery cells obtained in step (2) neatly in a 1L reactor, add 260mL of leaching solvent (the volume ratio of leaching solvent to battery cell is 1:1), completely submerge the battery cells in the leaching solvent, and let them stand at room temperature for 48 hours. Remove the battery cells and recover the leaching solution. At this time, the electrolyte is transferred from the battery cells to the leaching solution. The leaching solution consists of leaching solvent and leached electrolyte.

[0068] Step (4): The leachate was distilled for 5 hours under a vacuum of 1000 Pa and a temperature of 10°C. The mass of mixed solvent 1 recovered by condensation in a cold trap was approximately 282.1 g. The components were mainly composed of DMC, EMC, and acetonitrile, as shown in Table 4. The DMC in mixed solvent 1 mainly came from the added leachate solvent and the DMC in the residual electrolyte in the battery cell. The acetonitrile came from the leachate solvent, and the EMC came from the residual electrolyte in the battery cell. EMC can dissolve lithium hexafluorophosphate well and can be directly recycled without further separation. Then, a second vacuum distillation was performed for 5 hours under a vacuum of 1000 Pa and a temperature of 60°C. The mass of the high-boiling-point solvent recovered by evaporation and condensation was approximately 28.7 g. The main components were PC and EC (high-boiling-point organic solvents from the residual electrolyte in the battery cell), as determined by gas chromatography. The component analysis results of the obtained mixed solvent 1 and mixed solvent 2 are shown in Table 4 below. The remaining solid was LiPF6, with a mass of 10.3 g.

[0069] Step (5): The electrolyte-free battery cell obtained in step (3) is disassembled in a refined manner, and the battery cell is decomposed into positive electrode plate, negative electrode plate and separator, and 20.9g of the disassembled product separator is obtained.

[0070] Step (6): De-powdering treatment of the positive electrode sheet. The positive electrode sheet obtained in step (5) is immersed in NMP, heated to 150℃, and left to stand for 5 hours. The positive electrode material is detached from the aluminum foil. 95.5g of positive current collector aluminum foil (with no black powder residue on the surface) is screened out. The de-powdering solution is filtered and the solid phase is dried to obtain 170.1g of positive electrode powder. The XRD of the positive electrode powder is tested as follows. Figure 4 As shown, only diffraction peaks of lithium iron phosphate were present, and no diffraction peaks of impurity components were found. The contents of aluminum and copper impurities in the powder were both below 100 ppm. The results of ICP determination of impurity content are shown in Table 5.

[0071] Step (7): De-powdering of the negative electrode sheet. The negative electrode sheet obtained in step (5) is soaked in deionized water and left to stand at room temperature for 8 hours. The negative electrode material falls off the copper foil. 62.7g of copper foil for the negative current collector is screened out (no black powder residue on the surface). The de-powdering solution is filtered and the solid phase is dried to obtain 116.2g of negative electrode powder. The content of aluminum and copper impurities in the powder is less than 100 ppm. The results of ICP determination of its impurity content are shown in Table 5.

[0072] Example 2:

[0073] In this embodiment, the leaching solvent used is: diethylene glycol dimethyl ether (11.1%) + nitrile (88.9%); the 32650 cylindrical lithium iron phosphate battery treated in this embodiment.

[0074] The specific recycling and processing steps are as follows:

[0075] Step (1): Same as step (1) in Example 1. The brine used is sodium chloride solution with a concentration of 15%. The standing time is 12h. The open circuit voltage after discharge is 0.7V.

[0076] Step (2): Same as step (2) in Example 1.

[0077] Step (3): Same as step (3) in Example 1. Select a 2L reactor, use 1300mL of leaching solvent (the ratio of leaching solvent to battery cell volume is 1:5), and let stand for 48 hours.

[0078] Step (4): Same as step (4) in Example 1. The vacuum degree of the first vacuum distillation was 500 Pa, the temperature was 50℃, and the distillation time was 10 h. The recovered solvent mass was approximately 1071.4 g. GC analysis showed that the components were mainly composed of DMC, EMC, diethylene glycol dimethyl ether, and nitrile, as shown in Table 4. The vacuum degree of the second distillation was 500 Pa, the temperature was 50℃, and the distillation time was 5 h. The recovered high-boiling-point solvent was 28.5 g. GC analysis showed that its components were composed of PC and EC, as shown in Table 4. The recovered solid LiPF6 mass was 10.2 g.

[0079] Step (5): Same as step (5) in Example 1. Approximately 20.9g of the disassembled membrane product was obtained.

[0080] Step (6): Same as step (6) in Example 1. Solvent: DNF, temperature: 50℃, time: 24h. The mass of aluminum foil obtained was 95.1g, and the mass of positive electrode powder was 169.2g. The content of aluminum and copper impurities in the powder was less than 100ppm. The results of ICP determination of impurity content are shown in Table 5.

[0081] Step (7): Same as step (7) in Example 1. Solution: acetone, time: 5h, recovered copper foil mass: 62.4g, recovered negative electrode powder mass: 115.6g, the content of aluminum and copper impurities in the powder is less than 100ppm, and the impurity content measured by ICP is shown in Table 5.

[0082] Example 3:

[0083] In this embodiment, the leaching solvent used is: propyl propionate (88.9%) + fluorobutyronitrile (11.1%); the treated square aluminum-cased battery has the battery model: LFP23140160-55Ah.

[0084] The specific recycling and processing steps are as follows:

[0085] Step (1): Same as step (1) in Example 1. The brine used is ferric sulfate solution with a concentration of 2%, a standing time of 96 hours, and an open circuit voltage of 0.4V after discharge.

[0086] Step (2): Cut off the square battery casing, remove the battery cell completely, and leave the electrolyte inside the battery cell.

[0087] Step (3): Arrange the five square battery cells obtained in step (2) neatly in a 10L reactor, add 2625mL of leaching solvent (the volume ratio of leaching solvent to battery cell is 1:1), let stand for 96h, take out the battery cells and recover the leaching solution, at this time the electrolyte is transferred from the battery cells to the leaching solution.

[0088] Step (4): Same as step (4) in Example 1. The vacuum degree of the first vacuum distillation was 10000 Pa, the temperature was 25℃, and the distillation time was 24 h. The recovered solvent mass was approximately 2912.1 g. Gas chromatography analysis showed that the components were mainly composed of DMC, EMC, ethyl propionate, and fluoroacetonitrile, as shown in Table 4. The vacuum degree of the second distillation was 10000 Pa, the temperature was 90℃, and the distillation time was 48 h. The recovered high-boiling-point solvent was 285.8 g. Gas chromatography analysis showed that its components were composed of PC and EC, as shown in Table 4. The recovered solid LiPF6 mass was 122.1 g.

[0089] Step (5): Same as step (5) in Example 1. Approximately 193.2g of the disassembled diaphragm product was obtained.

[0090] Step (6): Same as step (6) in Example 1. Solvent: DMSO, temperature: 100℃, time: 12h. The mass of aluminum foil obtained was 876.3g, and the mass of positive electrode powder was 1559.3g. The content of aluminum and copper impurities in the powder was less than 100ppm. The results of ICP determination of impurity content are shown in Table 5.

[0091] Step (7): Same as step (7) in Example 1. Solution: ethanol, time: 24h, recovered copper foil mass: 575.2g, recovered negative electrode powder mass: 1064.9g, the content of aluminum and copper impurities in the powder is less than 100ppm, and the impurity content measured by ICP is shown in Table 5.

[0092] Example 4:

[0093] In this embodiment, the leaching solvent used is: DMC (21%), acetonitrile (16%), perfluorohexanone (33%), ethoxypentafluorocyclotriphosphazene (14%), and anhydrous ethanol (16%); the 32650 cylindrical lithium iron phosphate battery treated in this embodiment.

[0094] The specific recycling and processing steps are as follows:

[0095] Steps (1)-(2): Consistent with steps (1)-(2) in Example 1.

[0096] Step (3): Arrange 50 battery cells obtained in step (2) neatly in a 10L reactor, add 5.2L of leaching solvent (leaching solvent to battery cell volume ratio of 1:2), and completely immerse the battery cells in the leaching solvent. Let stand at room temperature for 120 hours. Remove the battery cells and recover the leaching solution. At this time, the electrolyte is transferred from the battery cells to the leaching solution.

[0097] Step (4): Same as step (4) in Example 1. The vacuum degree of the first vacuum distillation was 1000 Pa, the temperature was 15℃, and the distillation time was 24 h. The recovered solvent mass was approximately 6346.9 g. GC analysis showed that the components were mainly composed of DMC, EMC, acetonitrile, perfluorohexanone, ethanol, and ethoxypentafluorocyclophosphamide, as shown in Table 4. The vacuum degree of the second distillation was 1000 Pa, the temperature was 70℃, and the distillation time was 24 h. The recovered high-boiling-point solvent was 279.2 g. GC analysis showed that its components were composed of PC and EC, as shown in Table 4. The recovered solid LiPF6 mass was 99.7 g.

[0098] Step (5): Same as step (5) in Example 1. Approximately 210.3g of the disassembled membrane product was obtained.

[0099] Step (6): Same as step (6) in Example 1. The mass of aluminum foil obtained was 953.7g, and the mass of positive electrode powder was 1697.1g. The content of aluminum and copper impurities in the powder was less than 100ppm. The results of ICP measurement of impurity content are shown in Table 5.

[0100] Step (7): Same as step (7) in Example 1. The mass of copper foil recovered was 625.9g, and the mass of negative electrode powder recovered was 1159.1g. The content of aluminum and copper impurities in the powder was less than 100ppm. The results of ICP determination of impurity content are shown in Table 5.

[0101] Examples 5-12:

[0102] In this embodiment, the leaching solvent formulation is shown in Table 1, and the 32650 cylindrical lithium iron phosphate battery processed in this embodiment is shown in Table 1.

[0103] The specific recycling and processing steps are as follows:

[0104] Steps (1)-(2): Consistent with steps (1)-(2) in Example 4.

[0105] Step (3): Same as step (3) in Example 4. The amount of leaching solvent used and the standing time are shown in Table 3.

[0106] Step (4): Same as step (4) in Example 4. The parameters such as vacuum degree, temperature, distillation time of the first vacuum distillation and vacuum degree, temperature, distillation time of the second vacuum distillation are shown in Table 3. The mass of low-boiling solvent, component analysis, mass of high-boiling solvent, component analysis, and mass of recovered LiPF6 are shown in Tables 2 and 4.

[0107] Step (5): Same as step (5) in Example 4. The quality of the disassembled membrane is shown in Table 2.

[0108] Steps (6)-(7): Consistent with steps (6)-(7) in Example 4. The mass of recycled aluminum foil, positive electrode powder, copper foil, and negative electrode powder are shown in Table 2. The impurity content analysis of the positive electrode powder and negative electrode powder is shown in Table 5.

[0109] The leachate used in Example 5 was the low-boiling-point solution recovered in Example 4, indicating that the low-boiling-point mixed solution recovered during the first vacuum distillation process can be used as a leachate solvent.

[0110] Comparative Example 1:

[0111] In this embodiment, the leaching solvent used is dimethyl carbonate solvent (100%); the 32650 cylindrical lithium iron phosphate battery used in this embodiment is...

[0112] The specific recycling and processing steps are as follows:

[0113] Steps (1)-(2): Consistent with steps (1)-(2) in Example 1.

[0114] Step (3): Same as step (3) in Example 1. Five battery cells obtained in step (2) were neatly stacked in a 2L reactor. 520mL of leaching solvent (leaching solvent to battery cell volume ratio of 1:2) was added, completely submerging the battery cells. The mixture was left to stand at room temperature for 120 hours. The battery cells and leaching solution were then removed. The leaching solution was analyzed by IC (ion chromatography), and the results are as follows: Figure 5 As shown, only 92 ppm of LiPF6 remained in the leaching recovery solution. Furthermore, strong LiPO2F2 and LiF peaks were observed in the test results, indicating that LiPF6 decomposed. The dielectric constant of pure DMC solvent is relatively low, only 3.1. The proportion of Li+ solvated structures formed by lithium hexafluorophosphate dissolved in DMC is low, making it easier for lithium hexafluorophosphate molecules to come into contact with water molecules and undergo a decomposition reaction.

[0115] Table 1: Leaching solvent formulation ratios in each embodiment

[0116]

[0117]

[0118] Table 2: Mass of recovered components in each example

[0119]

[0120] Table 3: Process Conditions for Each Embodiment

[0121]

[0122]

[0123] Table 4: Component composition and mass percentage of mixed solvent 1 and mixed solvent 2 in each embodiment

[0124]

[0125]

[0126] Table 5 shows the percentage of copper and aluminum impurities in the positive and negative electrode powders in each embodiment.

[0127]

[0128] The results of Examples 1-12 above show that the method of the present invention can achieve the complete recycling of waste lithium-ion batteries, and the recycled components have high purity and low impurity content. Furthermore, it can utilize distillation to rapidly separate the leaching solvent from the high-boiling-point solvent in the electrolyte, allowing the leaching solvent to be easily recycled. The processing procedure is simple and low-cost.

[0129] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for recycling and processing all components of waste lithium-ion batteries, characterized in that, The processing steps include the following: (1) After discharging and shell cutting of waste lithium-ion batteries, the complete cells are taken out and the cells are added to the leaching solvent for soaking treatment to obtain cells without electrolyte and leaching solution containing electrolyte. (2) The electrolyte-containing leachate is separated into components by stepwise vacuum distillation to recover mixed solvent 1 and lithium salt. The mixed solvent 1 is recycled as a leachate solvent directly or after being adjusted in proportion. (3) The electrolyte-free battery cell is disassembled into positive electrode plate, negative electrode plate and separator for separate processing and recycling.

2. The method for recycling and processing all components of waste lithium-ion batteries according to claim 1, characterized in that, The discharge mentioned in step (1) refers to immersing the waste lithium-ion battery in a salt solution for discharge until the open circuit voltage drops below 1.5V; the salt solution refers to an aqueous solution with a mass concentration of 2wt% to 15wt% containing one or more salts of sodium chloride, sodium sulfate, and ferric sulfate.

3. The method for recycling and processing all components of waste lithium-ion batteries according to claim 1, characterized in that, The amount of leaching solvent added in step (1) is 1 to 5 times the volume of the battery cell; the soaking treatment is carried out under normal temperature and static conditions, and the soaking treatment time is 2 to 10 days.

4. The method for recycling and processing all components of waste lithium-ion batteries according to claim 1, characterized in that, The leaching solvent includes a first component and a second component; The first component is selected from carbonates and / or carboxylic esters and / or ethers; The second component is selected from nitrile compounds; Based on the total mass of the leaching solvent, the mass ratio of the first component to the second component is 0.125 to 8.

5. A method for recycling and processing all components of waste lithium-ion batteries according to claim 4, characterized in that, The leaching solvent in step (1) also includes a third component, a fourth component, and a co-solvent; Based on the total mass of the leaching solvent, the mass percentage of each component is as follows: Component 1 5%–40%, Component 2 5%–40%, Component 3 5%–20%, Component 4 10%–60%, and co-solvent 5%–40%. The third component is a compound as shown in Formula I below; R1 to R6 are the same or different fluorine substituents, ethoxy groups, fluorine-substituted methoxy groups, fluorine-substituted ethoxy groups, or phenoxy groups; The fourth component is at least one of perfluorohexanone, perfluoroheptanone, perfluorooctanone, and perfluorononanone.

6. The method for recycling and processing all components of waste lithium-ion batteries according to claim 4, characterized in that, The first component is selected from one or more of the following: dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, dipropyl carbonate, methyl formate, methyl acetate, ethyl formate, ethyl acetate, methyl propionate, ethyl propionate, propyl acetate, propyl propionate, butyl propionate, propyl butyrate, butyl butyrate, diethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, ethyl monofluoroacetate, ethyl trifluoroacetate, butyl trifluoroacetate, trifluoroethyl butyrate, methyl trifluoroethyl carbonate, and dimethyl sulfite.

7. A method for recycling and processing all components of waste lithium-ion batteries according to claim 4, characterized in that, The second component is selected from one or more of acetonitrile, propionitrile, butyronitrile, fluoroacetonitrile, and chloroacetonitrile.

8. A method for recycling and processing all components of waste lithium-ion batteries according to claim 4, characterized in that, The co-solvent is selected from one or more of anhydrous ethanol, propanol, acetone, butanone, and isopropanol.

9. A method for recycling and processing all components of waste lithium-ion batteries according to claim 1, characterized in that, The specific steps for component separation by stepwise vacuum distillation in step (2) are as follows: First, the mixture is kept under vacuum of 500-10000 Pa and temperature of 10-50℃ for 5-48 hours, and the mixed solvent 1 is recovered by distillation; the remaining solution is kept under vacuum of 500-10000 Pa and temperature of 50-90℃ for 5-48 hours, and the mixed solvent 2 and the lithium salt are recovered by distillation; wherein the boiling point of the mixed solvent 1 is lower than that of the mixed solvent 2.

10. A method for recycling and processing all components of waste lithium-ion batteries according to claim 1, characterized in that, The positive electrode obtained in step (3) is further processed and recycled using the following method: The positive electrode sheet is immersed in eluent 1 to dissolve the positive electrode binder and perform de-powdering treatment to obtain a positive electrode current collector and a de-powdering solution 1. The de-powdering solution 1 is filtered and the solid phase is dried to obtain positive electrode powder. The eluent 1 includes one or more solvents selected from N-methylpyrrolidone, N,N-dimethylformamide and dimethyl sulfoxide. The de-powdering treatment refers to standing de-powdering treatment at a temperature of 50-150°C for 5-24 hours.

11. A method for recycling and processing all components of waste lithium-ion batteries according to claim 1, characterized in that, The negative electrode sheet obtained in step (3) is further processed and recycled using the following method: The negative electrode sheet is immersed in eluent 2 to dissolve the negative electrode binder and perform de-powdering treatment to obtain a negative electrode current collector and de-powdering solution 2. The de-powdering solution 2 is filtered and the solid phase is dried to obtain negative electrode powder. The eluent 2 includes a mixture of one or more solvents such as deionized water, ethanol and acetone. The de-powdering treatment refers to standing de-powdering treatment at room temperature for 5 to 24 hours.

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