Method for recycling waste batteries by using eutectic solvent

Abstract

The invention belongs to the technical field of battery recovery, and relates to a method for recovering a waste battery by using a deep-eutectic solvent, which comprises the following steps: stirring a waste battery crushed material and the deep-eutectic solvent to react, and then carrying out solid-liquid separation; carrying out countercurrent washing on the obtained solid by using a deep eutectic solvent, and then drying to obtain a dried solid material; continuously performing fine separation on the dried solid material to obtain solid components of the battery; and carrying out negative pressure distillation on the obtained separation liquid, and separating to obtain the eutectic solvent and the electrolyte. According to the method for recycling the waste battery through the eutectic solvent, rapid separation of the electrolyte and the binder from the positive and negative electrode powder is achieved, the purity of the waste positive and negative electrode powder is improved, repair, regeneration and reutilization of subsequent materials are facilitated, meanwhile, harmless, green and efficient separation and recycling of the electrolyte of the waste battery are achieved, and the method is suitable for industrial production. And the recycled electrolyte can be used for follow-up repair and reutilization, so that the additional value is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of battery recycling and relates to a method for recycling waste batteries by utilizing a low eutectic solvent. Background Art

[0002] According to the latest statistics, the global new energy vehicle industry is developing rapidly. In 2023, global new energy vehicle sales will reach 14.653 million units, a year-on-year increase of 35.4%, of which China's new energy vehicle sales will reach 9.495 million units, accounting for 64.8% of global sales. Looking ahead, it is expected that global new energy vehicle sales will reach 18.30 million units in 2024, of which China's new energy vehicle sales will reach 11.80 million units, and global new energy vehicle sales will reach 47 million units in 2030. Since June 2024, the penetration rate of new energy vehicles in my country has exceeded 50% for the first time, and China will fully enter the new energy era.

[0003] With the rapid development of new energy vehicles, the amount of power batteries has increased sharply, and the power batteries are facing large-scale retirement. According to the data of China New Energy Vehicle Power Battery Recycling Industry Collaborative Development Alliance (CABRCA), the amount of retired power batteries in my country will reach 20.2GWh in 2024, and 402,900 new energy vehicles will be retired, a year-on-year increase of 48.53% and 46.56%. In 2030, it will reach 148.7GWh (about 900,000 tons) and 2.9891 million vehicles. From 2025 to 2030, the average annual compound growth rate of retired batteries and retired new energy vehicles will reach 37.64% and 38.11% respectively.

[0004] While my country's new energy vehicle industry is developing rapidly, it will also face risks in terms of limited resources and environmental safety. On the one hand, new energy vehicle batteries require resources such as nickel, cobalt and lithium, which are globally scarce resources. my country's external dependence on resources is even higher. In 2023, my country's external dependence on nickel, cobalt and lithium will reach 93%, 98% and 63% respectively; on the other hand, the life of power batteries is usually 5 to 8 years. The electrolyte, positive electrode materials (heavy metals), shell materials, diaphragms, etc. in the battery will cause varying degrees of pollution to the environment, and some of them are hazardous waste. The large-scale retirement of power lithium batteries will bring serious environmental problems and safety hazards.

[0005] Lithium batteries contain components such as positive electrode powder, negative electrode powder, electrolyte, binder and shell. The electrolyte mainly consists of organic solvents such as ethylene carbonate (EC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC). The binder mainly consists of polyvinylidene fluoride (PVDF) organic matter. At present, the pretreatment method for organic matters such as binders in the positive and negative electrodes of retired power batteries and battery electrolytes is usually a high-temperature roasting method. First, the battery is crushed as a whole, and then the crushed materials are placed in a rotary kiln for high-temperature combustion treatment. For example, CN118180109A discloses a method for pre-treating and crushing waste power batteries, and then the fragments are placed in a pyrolysis rotary kiln for high-temperature treatment, and the waste gas generated is discharged to the waste gas treatment system. This method has the following problems: (1) high energy consumption at high temperature and high special requirements such as equipment corrosion resistance; (2) the electrolyte and binder are organic matter, which may produce dioxins and other components after combustion, which will affect human health and environmental safety; (3) the electrolyte and binder are not effectively recovered, resulting in waste.

[0006] Alternatively, the electrolyte can be removed by multiple washings with an alkaline solution. This method also has the following problems: (1) the alkaline solution method consumes a large amount of reagents, generates a large amount of wastewater that is difficult to treat, and has a great impact on the environment; (2) it can only partially remove some salts in the electrolyte and has little effect on organic solvents such as esters and binders.

[0007] Low eutectic solvents are made by mixing two or more substances in a certain proportion. Their melting point is significantly lower than the melting point of each single component. This characteristic makes their preparation cost low. At the same time, due to the flexibility of their composition, the formula can be adjusted as needed, so they have a wide range of uses. The advantages of low eutectic solvents are wide sources, low cost, easy preparation, biodegradability and environmental protection. And low eutectic solvents also have excellent solubility and can dissolve a variety of polar and non-polar molecules, which makes them widely used in synthetic chemistry, extraction, solvent extraction, catalytic reactions and nanoparticle production. Summary of the invention

[0008] In view of the deficiencies in the prior art, the present invention provides a method for recycling waste batteries using a low eutectic solvent, which can be used to recycle positive and negative electrode materials, electrolytes, etc.

[0009] One object of the present invention is achieved by the following technical solutions:

[0010] A method for recycling waste batteries using a deep eutectic solvent comprises the following steps:

[0011] S1. crushing the waste batteries, stirring and reacting the crushed materials with a low eutectic solvent, and then separating the solid and the liquid to obtain a solid and a separated liquid;

[0012] S2, the solid obtained in step S1 is counter-washed with a low eutectic solvent, and then dried to obtain a dried solid material; the dried solid material is further subjected to fine separation including secondary crushing, screening, air separation, and gravity separation to obtain a battery solid component, and the battery solid component includes: positive electrode material, negative electrode material, negative electrode current collector particles, positive electrode current collector particles, and a separator;

[0013] S3. The separated liquid obtained in step S1 is subjected to negative pressure distillation to separate a low eutectic solvent and an electrolyte.

[0014] Before crushing used batteries, discharge them completely to avoid potential risks during the disposal process.

[0015] Preferably, the waste battery is a waste lithium battery; further, the waste lithium battery is a compound of one or more of waste ternary lithium battery, waste lithium iron phosphate battery, waste lithium cobalt oxide battery, waste lithium manganese oxide battery and waste lithium titanate oxide battery. Generally speaking, the positive electrode material of ternary lithium battery is a ternary compound of nickel cobalt manganese (Ni-Mn-Co), and the positive electrode material of lithium iron phosphate battery is lithium iron phosphate (LiFePO 4 ), the positive electrode material of the cobalt oxide lithium battery is lithium cobalt oxide (LiCoO 2 ), the positive electrode material of lithium manganese oxide battery is lithium manganese oxide (LiMn 2 O4), the positive electrode material of lithium titanate battery is lithium titanate (Li 4 Ti 5 O 12 ); Each lithium battery usually uses carbon materials such as graphite as the negative electrode material.

[0016] Preferably, the hydrogen bond acceptor of the deep eutectic solvent is choline chloride, and the hydrogen bond donor is one or more of alcohols, esters, carboxylic acids, and amines.

[0017] That is, the deep eutectic solvent is one or more of choline chloride-alcohol deep eutectic solvents, choline chloride-carboxylic acid deep eutectic solvents, choline chloride-ester deep eutectic solvents, and choline chloride-amine deep eutectic solvents.

[0018] Alcohols may be listed as one or more of glycerol, ethylene glycol, propylene glycol, and butylene glycol; esters may be listed as one or more of monomethyl oxalate, dimethyl oxalate, and diethyl oxalate; carboxylic acids may be listed as one or more of acetic acid, propionic acid, and oxalic acid; amines may be listed as one or more of urea, acetamide, and ethanolamine.

[0019] More preferably, the low eutectic solvent is one or more of choline chloride-urea, choline chloride-glycerol, choline chloride-acetic acid, and choline chloride-ethylene glycol.

[0020] More preferably, the low eutectic solvent is choline chloride-urea. When the low eutectic solvent is choline chloride-urea, more electrolyte can be dissolved, thereby improving the electrolyte leaching rate.

[0021] Preferably, in the low eutectic solvent, the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:4 to 4:1.

[0022] Preferably, the ratio of the mass of the crushed material to the volume of the low eutectic solvent is 1 g: 5-100 ml.

[0023] Preferably, the reaction temperature of step S1 is 20 to 120° C., more preferably 50 to 80° C.; the reaction time of step S1 is 0.5 to 6 hours, more preferably 2 to 4 hours. The reaction is carried out under stirring conditions, and the stirring speed can be 100 to 1000 rpm.

[0024] Preferably, the reaction in step S1 is carried out with the assistance of ultrasound, and the frequency of the ultrasound is 25 to 100 KHz, more preferably 30 to 50 KHz.

[0025] The solid-liquid separation means in step S1 include centrifugation, filtration, sedimentation, etc.

[0026] The crushed materials obtained by crushing waste batteries usually include positive electrode materials, negative electrode materials, positive electrode current collectors, negative electrode current collectors, binders, diaphragms, electrolytes, battery shells, etc. The binder is usually a high molecular polymer such as polyvinylidene fluoride (PVDF), and the electrolyte usually includes organic solvents such as ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, propylene carbonate, and lithium salts. The crushed materials are reacted with a low eutectic solvent of a certain component at a certain temperature and time, so that the electrolyte and the binder are dissolved in the low eutectic solvent, while the solid components in the crushed materials such as positive electrode materials, negative electrode materials, positive electrode current collectors, negative electrode current collectors, diaphragms, battery shells, etc. are insoluble in the low eutectic solvent, and the solid components and the separation liquid containing the electrolyte and the binder are obtained by solid-liquid separation.

[0027] Preferably, in step S2, the countercurrent washing is performed 1 to 5 times. The ratio of the volume of the deep eutectic solvent used each time to the mass of the solid is 1 to 10 ml: 1 g, more preferably 1 to 5 ml: 1 g.

[0028] Preferably, the drying temperature in step S2 is 60 to 200° C., more preferably 80 to 150° C.; the drying time is 1 to 8 hours, more preferably 2 to 4 hours.

[0029] The dried solid material is further subjected to fine separation including secondary crushing, screening, air separation and gravity separation to obtain positive electrode materials, negative electrode materials, negative electrode current collector particles, positive electrode current collector particles, separators, battery shells, etc.

[0030] Secondary high-speed crushing can separate the positive and negative electrode powders from the current collector, multi-level fine screening can separate the positive and negative electrode powders from the current collector, air separation can separate lighter materials such as diaphragms, and then gravity separation (copper and aluminum have different specific gravities) can separate copper particles and aluminum particles.

[0031] When the positive electrode current collector of the battery is aluminum foil and the negative electrode current collector is copper foil, the negative electrode current collector particles and the positive electrode current collector particles in the battery solid components separated in step S2 are copper particles and aluminum particles respectively.

[0032] Preferably, the temperature of the negative pressure distillation in step S3 is 80 to 200° C., more preferably 100 to 150° C.; the pressure of the negative pressure distillation is -0.6 MPa to 0 MPa, more preferably -0.4 to -0.1 MPa.

[0033] The separated liquid obtained in step S1 includes an electrolyte and a low eutectic solvent. The separated liquid is subjected to negative pressure distillation under certain conditions to obtain a low eutectic solvent and an electrolyte. The electrolyte can be reused after further supplementing with electrolytes.

[0034] The operation sequence of steps S2 and S3 of the present invention is not affected by the numbers S2 and S3, and any one of the two steps can be performed first.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] 1. The present invention adopts a low eutectic solvent to treat waste batteries, which can effectively separate the electrolyte and the binder, directly obtain pure positive and negative electrode materials, and realize the recovery of the electrolyte at the same time; the recovery method is green, environmentally friendly and efficient, avoiding the high energy consumption and environmental pollution problems of traditional high-temperature roasting method and alkaline solution washing method.

[0037] 2. The method of recycling waste batteries using a low eutectic solvent of the present invention realizes the rapid separation of the binder from the positive and negative electrode powders, improves the purity of the waste positive and negative electrode powders, facilitates the subsequent repair, regeneration and reuse of materials, and also realizes the harmless, green and efficient separation and recycling of waste battery electrolytes. The recovered electrolyte can be used for subsequent repair and reuse to increase added value.

[0038] 3. The low eutectic solvent used in the present invention can be recycled and reused after separating the electrolyte, and is a green recyclable solvent. The recycling of the low eutectic solvent reduces the processing cost and improves the economic benefit.

[0039] 4. The recycling method of the present invention removes organic matter, prevents the organic matter from entering the subsequent wet regeneration process of the battery solid components, reduces the pollution of the organic matter to the water system, and reduces the water treatment cost. DETAILED DESCRIPTION

[0040] The technical scheme of the present invention is further described below by specific embodiments. It should be understood that the specific embodiments described herein are only used to help understand the present invention and are not intended to be used for specific limitations of the present invention. Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commonly used raw materials in the art, and the methods used in the embodiments are all conventional methods in the art.

[0041] The waste lithium iron phosphate battery used in the following embodiments includes lithium iron phosphate as a positive electrode material, graphite as a negative electrode material, aluminum foil, copper foil, PVDF as a binder, a polypropylene diaphragm, an electrolyte (lithium hexafluorophosphate + dimethyl carbonate), an aluminum alloy battery casing, etc.

[0042] The waste ternary lithium battery used in the following examples includes the positive electrode material LiMn 0.15 Co 0.25 Ni 0.6 O. Negative electrode materials: graphite, aluminum foil, copper foil, binder PVDF, polypropylene diaphragm, electrolyte (lithium hexafluorophosphate + ethylene carbonate), stainless steel battery casing, etc.

[0043] The waste lithium cobalt oxide battery used in the following embodiments includes positive electrode material lithium cobalt oxide, negative electrode material graphite, aluminum foil, copper foil, binder CMC, polypropylene separator, electrolyte (lithium bistrifluoromethanesulfonyl imide LiTFSI+ethylene carbonate), aluminum alloy battery casing, etc.

[0044] Example 1

[0045] The method for recycling waste lithium iron phosphate batteries provided in this embodiment comprises the following steps:

[0046] (1) The discharged waste lithium iron phosphate battery was crushed, and 50 g of the crushed material and 500 ml of choline chloride-urea low eutectic solvent (the molar ratio of choline chloride to urea was 1:2) were stirred in a reactor (400 rpm), and an ultrasonic device was turned on at 40 kHz to assist the reaction. After reacting at 60° C. for 2 h, the reaction was filtered to obtain a solid and a filtrate;

[0047] (2) The solid obtained in step (1) is counter-currently washed twice with a choline chloride-urea low eutectic solvent (the molar ratio is the same as (1)), and the ratio of the volume of the low eutectic solvent used each time to the mass of the solid is 2 ml: 1 g, and then the filter cake is dried at 80° C. for 3 h to obtain a dried solid material; the dried solid material is further subjected to fine separation including secondary crushing, screening, air separation, and gravity separation to obtain lithium iron phosphate powder, graphite powder, aluminum particles, copper particles, polypropylene diaphragm and aluminum alloy battery casing, which can be subsequently recycled;

[0048] (3) The filtrate obtained in step S1 and the choline chloride-urea low eutectic solvent collected after countercurrent washing in step S2 are subjected to negative pressure distillation at 140° C. and −0.2 MPa to separate the low eutectic solvent and the electrolyte (dimethyl carbonate containing lithium hexafluorophosphate). The low eutectic solvent can be returned for reuse, and the electrolyte can be reused after further supplementing lithium salt.

[0049] The electrolyte solvent leaching rate in step (1) of this embodiment is 93.2%.

[0050] Example 2

[0051] The method for recycling waste lithium iron phosphate batteries provided in this embodiment comprises the following steps:

[0052] (1) The discharged waste lithium iron phosphate battery was crushed, and 50 g of the crushed material and 600 ml of choline chloride-urea low eutectic solvent (the molar ratio of choline chloride to urea was 1:1) were stirred in a reactor (300 rpm), and an ultrasonic device was turned on at 25 kHz to assist the reaction. After reacting at 25° C. for 6 h, the reaction was filtered to obtain a solid and a filtrate;

[0053] (2) The solid obtained in step (1) is counter-currently washed twice with a choline chloride-urea low eutectic solvent (the molar ratio is the same as (1)), and the ratio of the volume of the low eutectic solvent used each time to the mass of the solid is 1 ml:1 g, and then the filter cake is dried at 60° C. for 6 h to obtain a dried solid material; the dried solid material is further subjected to fine separation including secondary crushing, screening, air separation, gravity separation, and flotation to separate lithium iron phosphate powder, graphite powder, aluminum particles, copper particles, polypropylene diaphragm and aluminum alloy battery casing, and these materials can be subsequently recycled;

[0054] (3) The filtrate obtained in step S1 and the choline chloride-urea low eutectic solvent collected after countercurrent washing in step S2 are subjected to negative pressure distillation at 80° C. and −0.4 MPa to separate the low eutectic solvent and the electrolyte (dimethyl carbonate containing lithium hexafluorophosphate). The low eutectic solvent can be returned for reuse, and the electrolyte can be reused after further supplementing lithium salt.

[0055] The electrolyte solvent leaching rate in step (1) of this embodiment is 90.6%.

[0056] Example 3

[0057] The method for recycling waste lithium iron phosphate batteries provided in this embodiment comprises the following steps:

[0058] (1) The discharged waste lithium iron phosphate battery was crushed, and 50 g of the crushed material and 400 ml of choline chloride-urea low eutectic solvent (the molar ratio of choline chloride to urea was 2:1) were stirred in a reactor (500 rpm), and an ultrasonic device was turned on at 60 KHz for auxiliary reaction. After reacting at 80° C. for 3 h, the reaction was filtered to obtain a solid and a filtrate;

[0059] (2) The solid obtained in step (1) is counter-currently washed twice with a choline chloride-urea low eutectic solvent (the molar ratio is the same as (1)), and the ratio of the volume of the low eutectic solvent used each time to the mass of the solid is 3 ml: 1 g, and then the filter cake is dried at 100° C. for 2 h to obtain a dried solid material; the dried solid material is further subjected to fine separation including secondary crushing, screening, air separation, gravity separation, and flotation to separate lithium iron phosphate powder, graphite powder, aluminum particles, copper particles, polypropylene diaphragm and aluminum alloy battery casing, which can be subsequently recycled;

[0060] (3) The filtrate obtained in step S1 and the choline chloride-urea low eutectic solvent collected after countercurrent washing in step S2 are subjected to negative pressure distillation at 100° C. and −0.3 MPa to separate the low eutectic solvent and the electrolyte (dimethyl carbonate containing lithium hexafluorophosphate). The low eutectic solvent can be returned for reuse, and the electrolyte can be reused after further supplementing lithium salt.

[0061] The electrolyte solvent leaching rate in step (1) of this embodiment is 96.8%.

[0062] Example 4

[0063] The difference between Example 4 and Example 1 is that Example 4 uses choline chloride-glycerol deep eutectic solvent (the molar ratio of choline chloride to glycerol is 1:2) to replace the choline chloride-urea deep eutectic solvent of Example 1. The rest is the same as Example 4.

[0064] The electrolyte solvent leaching rate in step (1) of this embodiment is 88.6%.

[0065] Example 5

[0066] The difference between Example 5 and Example 1 is that Example 5 uses choline chloride-acetic acid deep eutectic solvent (the molar ratio of choline chloride to acetic acid is 1:2) to replace the choline chloride-acetic acid deep eutectic solvent of Example 1. The rest is the same as Example 4.

[0067] The electrolyte solvent leaching rate in step (1) of this embodiment is 89.6%.

[0068] Example 6

[0069] The waste LiMn provided in this embodiment 0.15 Co0.25 Ni 0.6 The recycling method of O batteries comprises the following steps:

[0070] (1) Discharged waste LiMn 0.15 Co 0.25 Ni 0.6 The O cell was crushed, and 50 g of the crushed material and 500 ml of a choline chloride-urea low eutectic solvent (the molar ratio of choline chloride to urea was 1:2) were stirred in a reactor (500 rpm), and an ultrasonic device was turned on at 80 KHz for auxiliary reaction. After reacting at 100 ° C for 1.5 h, the mixture was filtered to obtain a solid and a filtrate;

[0071] (2) The solid obtained in step (1) is counter-washed twice with a choline chloride-urea low eutectic solvent (the molar ratio is the same as (1)), and the ratio of the volume of the low eutectic solvent used each time to the mass of the solid is 2.5 ml: 1 g, and then the filter cake is dried at 120° C. for 1.5 h to obtain a dried solid material; the dried solid material is further subjected to fine separation including secondary crushing, screening, air separation, gravity separation, and flotation to separate LiMn 0.15 Co 0.25 Ni 0.6 O powder, graphite powder, aluminum particles, copper particles, polypropylene separator and stainless steel battery casing, these materials can be recycled later;

[0072] (3) The filtrate obtained in step S1 and the choline chloride-urea low eutectic solvent collected after countercurrent washing in step S2 are subjected to negative pressure distillation at 120° C. and −0.1 MPa to separate the low eutectic solvent and the electrolyte (ethylene carbonate containing lithium hexafluorophosphate). The low eutectic solvent can be returned for reuse, and the electrolyte can be reused after further supplementing lithium salt.

[0073] The electrolyte solvent leaching rate in step (1) of this embodiment is 94.8%.

[0074] Example 7

[0075] The method for recycling waste lithium cobalt oxide batteries provided in this embodiment comprises the following steps:

[0076] (1) The discharged waste lithium cobalt oxide battery was crushed, and 50 g of the crushed material and 1000 ml of choline chloride-urea low eutectic solvent (the molar ratio of choline chloride to urea was 1:2) were stirred in a reactor (600 rpm), and an ultrasonic device was turned on at 100 KHz for auxiliary reaction. After reacting at 120° C. for 1 hour, the reaction was filtered to obtain a solid and a filtrate;

[0077] (2) The solid obtained in step (1) is counter-currently washed twice with a choline chloride-urea low eutectic solvent (the molar ratio is the same as (1)), and the ratio of the volume of the low eutectic solvent used each time to the mass of the solid is 4 ml: 1 g, and then the filter cake is dried at 180° C. for 1 hour to obtain a dried solid material; the dried solid material is further subjected to fine separation including secondary crushing, screening, air separation, gravity separation, and flotation to separate lithium cobalt oxide powder, graphite powder, aluminum particles, copper particles, polypropylene diaphragm and aluminum alloy battery casing, and these materials can be subsequently recycled;

[0078] (3) The filtrate obtained in step S1 and the choline chloride-urea low eutectic solvent collected after countercurrent washing in step S2 are subjected to negative pressure distillation at 200° C. and 0 MPa to separate the low eutectic solvent and the electrolyte (ethylene carbonate containing LiTFSI). The low eutectic solvent can be returned for reuse, and the electrolyte can be reused after further supplementing lithium salt.

[0079] The electrolyte solvent leaching rate in step (1) of this embodiment is 92.7%.

[0080] The various aspects, embodiments, and features of the present invention should be considered to be illustrative in all aspects and not limiting of the present invention, the scope of which is defined solely by the claims. Other embodiments, modifications, and uses will be apparent to those skilled in the art without departing from the spirit and scope of the claimed invention.

[0081] In the preparation method of the present invention, the order of each step is not limited to the order listed. For those skilled in the art, without creative work, the order of each step is also within the protection scope of the present invention. In addition, two or more steps or actions can be performed simultaneously.

[0082] Finally, it should be noted that the specific embodiments described herein are merely examples of the present invention, and are not intended to limit the implementation methods of the present invention. A person skilled in the art of the present invention may make various modifications or supplements to the specific embodiments described, or replace them in a similar manner. It is not necessary and impossible to provide all examples of all implementation methods here. However, these obvious changes or modifications derived from the essential spirit of the present invention still fall within the scope of protection of the present invention, and interpreting them as any additional limitation is contrary to the spirit of the present invention.

Claims

1. A method for recycling waste batteries using a deep eutectic solvent, comprising the following steps: S1. crushing the waste batteries, stirring and reacting the crushed materials with a low eutectic solvent, and then separating the solid and the liquid to obtain a solid and a separated liquid; S2, the solid obtained in step S1 is counter-washed with a low eutectic solvent, and then dried to obtain a dried solid material; the dried solid material is further subjected to fine separation including secondary crushing, screening, air separation, and gravity separation to obtain a battery solid component, and the battery solid component includes: positive electrode material, negative electrode material, negative electrode current collector particles, positive electrode current collector particles, and a separator; S3. The separated liquid obtained in step S1 is subjected to negative pressure distillation to separate a low eutectic solvent and an electrolyte.

2. The method according to claim 1, characterized in that: Before crushing the used batteries, discharge them first; The waste batteries are waste lithium batteries; The waste lithium battery is a compound of one or more of waste ternary lithium batteries, waste lithium iron phosphate batteries, waste lithium cobalt oxide batteries, waste lithium manganese oxide batteries, and waste lithium titanate batteries.

3. The method according to claim 1, characterized in that The hydrogen bond acceptor of the deep eutectic solvent is choline chloride, and the hydrogen bond donor is one or more of alcohols, esters, carboxylic acids, and amines.

4. The method according to claim 3, characterized in that In the low eutectic solvent, the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:4 to 4:

1.

5. The method according to any one of claims 1 to 4, characterized in that: The low eutectic solvent is one or more of choline chloride-urea, choline chloride-glycerol, choline chloride-acetic acid, and choline chloride-ethylene glycol.

6. The method according to claim 1, characterized in that In step S1, the ratio of the mass of the crushed material to the volume of the deep eutectic solvent is 1 g: 5-100 ml; And / or, the reaction in step S1 is carried out with the assistance of ultrasound, and the frequency of the ultrasound is 25-100 KHz.

7. The method according to claim 1, characterized in that The reaction temperature of step S1 is 20-120° C., and the reaction time is 0.5-6 h.

8. The method according to claim 1, characterized in that In step S2, the number of countercurrent washing is 1 to 5 times; The ratio of the volume of the low eutectic solvent used each time to the mass of the solid is 1-10 ml:1 g.

9. The method according to claim 1, characterized in that: The drying temperature in step S2 is 60-200° C., and the drying time is 1-8 hours.

10. The method according to claim 1, characterized in that The temperature of the negative pressure distillation in step S3 is 80 to 200° C., and the pressure of the negative pressure distillation is -0.6 MPa to 0 MPa.