Method for chemical degradation pretreatment of binder before disassembly of lithium battery

Abstract

The invention discloses a method for chemical degradation pretreatment of a binder before disassembly of a lithium battery, and relates to the technical field of lithium batteries, and the method comprises the following operation steps: S1, preparation of a pretreatment solution: adding a weakly alkaline compound into deionized water, and mixing to prepare the weakly alkaline pretreatment solution with the mass concentration of 5-15%, adding a fluorine ion complexing agent with the mass concentration of 0.1-0.5% into the weakly alkaline pretreatment solution, and uniformly stirring and mixing to obtain a reaction solution; s2, lithium battery pretreatment: performing surface cleaning and discharging treatment on the lithium battery; according to the method for chemical degradation pretreatment of the binder before disassembly of the lithium battery, a fluorine ion complexing agent is added into a weakly alkaline pretreatment solution, and the reaction balance is broken and the molecular chain breakage of the binder is accelerated by virtue of the action that the fluorine ion complexing agent and fluorine ions generated by degradation of the binder form a stable complex.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium batteries, in particular to a method for chemical degradation pretreatment of a lithium battery adhesive before disassembly. BACKGROUND

[0002] With the rapid development of new energy automobile, energy storage equipment and other industries, the demand for lithium batteries continues to rise, and the problem of recycling of waste lithium batteries has become increasingly prominent. Hard-shell lithium batteries are widely used in various electronic devices and vehicles due to their stable structure and high energy density, but such batteries face many problems during disassembly and recycling. Because the battery internal cells and the shell, and the cells are usually firmly bonded with PVDF adhesive, traditional physical disassembly methods require the application of a large external force, which can easily cause the crystal of the electrode material to break and the current collector to deform, thereby reducing the recycling quality and reuse value of the electrode material, and also causing potential safety hazards due to short circuits and electrolyte leakage.

[0003] In existing lithium battery recycling pretreatment technologies, high-temperature pyrolysis processes can break the molecular chains of the adhesive, but they need to be carried out in a high-temperature environment above 300℃, which has the problems of high energy consumption and easy oxidation and deterioration of the electrode material. Pure mechanical crushing and sorting technologies rely on the differences in physical properties of materials to separate components, but it is difficult to avoid the mixing of shell fragments into electrode powders, which causes the mixing of metal impurities, and the subsequent purification is difficult and costly. At the same time, traditional chemical degradation methods mostly use single alkaline solutions, which have the defects of slow reaction rate, incomplete degradation of the adhesive, and easy residue of the degradation products, and cannot meet the actual needs of efficient and non-destructive recycling of hard-shell lithium batteries.

[0004] Therefore, it is necessary to propose a method for chemical degradation pretreatment of a lithium battery adhesive before disassembly to solve the above problems. SUMMARY

[0005] The present application aims to provide a method for chemical degradation pretreatment of a lithium battery adhesive before disassembly, to solve the problems in existing lithium battery recycling pretreatment technologies, such as high-temperature pyrolysis processes that can break the molecular chains of the adhesive, but need to be carried out in a high-temperature environment above 300℃, which has the problems of high energy consumption and easy oxidation and deterioration of the electrode material, and pure mechanical crushing and sorting technologies that rely on the differences in physical properties of materials to separate components, but it is difficult to avoid the mixing of shell fragments into electrode powders, which causes the mixing of metal impurities, and the subsequent purification is difficult and costly.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solution: a method for chemical degradation pretreatment of a lithium battery adhesive before disassembly, comprising the following operation steps:

[0007] S1, preparing a pretreatment solution: adding a weakly alkaline compound into deionized water to prepare a weakly alkaline pretreatment solution with a mass concentration of 5%-15%, and then adding a fluoride complexing agent with a mass concentration of 0.1%-0.5% into the weakly alkaline pretreatment solution, stirring and mixing uniformly to obtain a reaction solution;

[0008] S2, pretreating the lithium battery: performing surface cleaning and discharging treatment on the lithium battery, applying a silicone sealant to the tab part of the lithium battery with a thickness of 1-2 mm, and standing for 2-4 hours until the silicone sealant is cured to complete the sealing treatment of the lithium battery; immersing the sealed lithium battery into the reaction solution, and performing gradient pressure soaking at a temperature of 25-35℃, and monitoring and adjusting the pH value of the reaction solution to maintain the pH value at 8.5-10.5;

[0009] S3, mechanical peeling and separation: taking out the soaked lithium battery and sequentially performing rinsing, drying and fixing; then applying a pushing force in the gap between the shell and the cell group of the lithium battery to separate the shell, and applying a pulling force from the edge of the cell group to separate the cells to obtain the cells;

[0010] S4, subsequent treatment: rinsing the separated lithium battery shell with deionized water, and then drying at a temperature of 60-80℃ for 30-60 minutes; wiping the cells with anhydrous ethanol, and then drying under normal temperature and ventilation conditions for 30-60 minutes; filtering the used reaction solution, and then detecting the concentration for recycling or neutralizing treatment to a pH value of 6-9 for compliant discharge.

[0011] Preferably, in S1, the weakly alkaline compound is one or both of sodium bicarbonate and sodium carbonate, and the fluoride complexing agent is calcium disodium ethylenediaminetetraacetate.

[0012] Preferably, in S1, the weakly alkaline compound and the deionized water are mixed by adding while stirring, and the stirring rate is 300-500 r / min and the stirring time is 15-30 minutes.

[0013] Preferably, in S2, the lithium battery is discharged at a discharge rate of 0.1C-0.2C until the voltage of the lithium battery is ≤0.5V.

[0014] Preferably, in S2, the sealed lithium battery is completely immersed in the reaction solution, and the liquid level of the reaction solution is controlled to be 5-10 mm higher than the top end of the lithium battery.

[0015] Preferably, in S2, the gradient pressure soaking is specifically performed as follows: maintaining normal pressure for the first 1 hour, then increasing the pressure by 0.1 MPa every 1 hour, and controlling the maximum pressure at 0.3 MPa.

[0016] Preferably, in S3, when the shell is separated, if the lithium battery is made of aluminum shell material, a uniform pushing force of 50-70 N is applied, and if it is made of steel shell material, a uniform pushing force of 80-100 N is applied.

[0017] Preferably, in S3, when the cells are separated, a precision mechanical tweezers or a small separation clamp is used.

[0018] Preferably, in S3, a 10-20 times high-definition microscope is used for full-time observation to monitor the separation state in real time.

[0019] Preferably, in S4, after concentration detection, if the solution concentration is within the effective range of 5%-15%, the solution is adjusted to the preset concentration by supplementing weak alkaline compounds and deionized water, and then recycled, and the recycling times are not more than 5 times, if the solution concentration is too low or has been deteriorated, the reaction solution is neutralized and discharged.

[0020] The technical effects and advantages of the present application are:

[0021] 1. By adding a fluoride ion complexing agent to the weak alkaline pretreatment solution, the fluoride ion complexing agent and the fluoride ion generated by the degradation of the binder form a stable complex, which breaks the reaction balance and accelerates the breaking of the molecular chain of the binder. Not only does it solve the problem of slow reaction rate and easy residue of traditional chemical degradation, but it also avoids the secondary pollution caused by the deposition of fluoride ions on the surface of the battery components. At the same time, the fluoride ion complexing agent does not react with the metal shell and electrode material, ensuring the selectivity of the treatment process.

[0022] 2. By using gradient pressure soaking method, the initial pressure is maintained at atmospheric pressure, and then the pressure is gradually increased to the preset value, which can gradually expand the small gap between the battery shell and the cell, and promote the reaction solution to penetrate the bonding interface more quickly and uniformly, effectively solving the problem of incomplete degradation of local binder caused by uneven solution penetration in the prior art, while avoiding the impact damage of high pressure to the battery structure.

[0023] 3. The reaction solution in the soaking process is dynamically monitored and accurately controlled by an online refractometer and a pH meter. When the solution concentration decreases by more than the threshold value, the raw materials are automatically supplemented to maintain the concentration stable, and the pH value is ensured to be within the appropriate range, realizing the accurate control of the reaction system, ensuring the consistency and stability of the binder degradation, and significantly improving the subsequent disassembly efficiency.

[0024] 4. This invention achieves efficient separation of the outer casing from the battery cell and between the battery cells at room temperature through a combination of "chemical pretreatment + gentle mechanical stripping". Compared with existing high-temperature pyrolysis technology, it significantly reduces energy consumption and avoids oxidation damage to electrode materials caused by high temperature. Compared with pure mechanical crushing and sorting technology, it effectively reduces crystal breakage of electrode materials caused by shear force, and avoids the problem of metal impurities caused by casing fragments mixed with electrode powder, thereby improving the recycling quality and reuse value of battery components and electrode materials.

[0025] 5. This invention filters and tests the reaction solution after use, allowing it to be recycled within the effective concentration range and with a reasonable number of cycles controlled. This reduces raw material consumption and processing costs, as well as waste liquid discharge. The expired solution is neutralized to neutral before being discharged in compliance with regulations or entrusted for disposal, which meets environmental protection requirements and contributes to the green and sustainable development of the lithium battery recycling industry. Attached Figure Description

[0026] Figure 1 This is a flowchart of the method for chemical degradation pretreatment of binders before disassembly of lithium batteries according to the present invention. Detailed Implementation

[0027] This invention provides, for example Figure 1 The method described is a pretreatment method for chemical degradation of binders before disassembling lithium batteries. It follows a core process of "pretreatment solution preparation—lithium battery pretreatment operation—mechanical peeling and separation—subsequent processing." First, a reaction solution is prepared, primarily composed of weakly alkaline compounds such as sodium bicarbonate and sodium carbonate, supplemented with a fluoride ion complexing agent. The concentration and ratio are precisely controlled to ensure reaction selectivity and efficiency. Then, the hard-shell lithium battery undergoes surface cleaning, discharge, and tab sealing. A gradient pressure immersion method promotes the penetration of the reaction solution and degradation of the binder, while an online refractometer and pH meter are used to dynamically control the immersion process. After pretreatment, the battery is dried, and then a precisely controlled push and pull mechanical peeling operation is performed to achieve non-destructive separation of the shell from the battery cell and between the battery cells. Finally, the separated battery components undergo targeted cleaning, and the reaction solution is filtered, tested, and then classified for recycling or compliant disposal. The entire process balances disassembly efficiency, material protection, and environmental requirements. The specific operation steps are as follows:

[0028] I. Preparation of Pretreatment Solution

[0029] Reagent selection: Select a weakly basic compound as the main body of the reaction, wherein the weakly basic compound is preferably one or both of sodium bicarbonate and sodium carbonate; such weakly basic reagents can better control the hydrolysis reaction rate of the binder (such as PVDF) inside the lithium battery, avoiding the accidental impact of excessive reaction on the internal structure of the lithium battery; at the same time, deionized water is selected as the solvent, and the characteristics of deionized water without impurity ions are used to exclude the interference of impurity ions in water on the reaction system, ensuring the purity and stability of the reaction.

[0030] Concentration adjustment: In a normal temperature environment, the selected weakly basic compound is slowly added to deionized water, mixed by stirring while adding, the stirring rate is controlled at 300-500 r / min, and the stirring time is 15-30 minutes, so as to make the weakly basic compound completely dissolved, and finally a weakly basic pretreatment solution with a mass concentration of 5%-15% is prepared. This concentration range can not only ensure sufficient ester exchange reaction with the binder, but also avoid potential impact of the solution on other parts of the lithium battery due to too high concentration.

[0031] Wherein, the stirring can be carried out by a magnetic stirrer.

[0032] Reaction enhancer addition: Add a mass concentration of 0.1%-0.5% of a fluoride ion complexing agent to the prepared weakly basic pretreatment solution to obtain a reaction solution. The fluoride ion complexing agent is preferably calcium disodium ethylenediaminetetraacetate. By forming a stable complex with fluoride ions generated during the degradation of the binder, the reaction equilibrium is broken and the breaking of the binder molecular chain is accelerated, while avoiding secondary pollution caused by the deposition of fluoride ions on the surface of the lithium battery parts.

[0033] Unlike the degradation method relying solely on alkaline solution in the prior art, the slow reaction rate and product residue of traditional chemical degradation are solved, and the complexing agent does not react with the metal shell and electrode material, ensuring the selectivity of the treatment process.

[0034] II. Lithium battery pretreatment operation

[0035] Lithium battery pretreatment preparation: Select an intact hard shell lithium battery to be disassembled, whose metal shell is made of aluminum or steel. First, clean the surface of the lithium battery by wiping it with a dust-free cloth dipped in anhydrous ethanol to remove dust, oil stains and other impurities, so as to avoid the impurities entering the subsequent reaction system. Then, discharge the lithium battery at a discharge rate of 0.1C-0.2C until the voltage of the lithium battery drops to ≤0.5V, the safe voltage range, to avoid safety hazards caused by residual power in the lithium battery during subsequent operations.

[0036] Sealing treatment: The tab part of the hard-shell lithium battery is sealed with a high-temperature-resistant and corrosion-resistant sealing material. The sealing method is to apply a layer of silicone rubber sealant with a thickness of 1-2 mm. This ensures a tight seal and prevents the pretreatment solution from seeping into the electrolyte area inside the lithium battery from the tab part during the soaking process, avoiding unnecessary reactions between the solution and the electrolyte.

[0037] Gradient pressure soaking: After sealing treatment, the hard-shell lithium battery is completely immersed in the reaction solution, with the liquid level controlled at 5-10 mm above the top end of the lithium battery. The soaking is carried out using a gradient pressure control method. The initial 1 hour is maintained at normal pressure, i.e., 1 standard atmosphere. Then the pressure is increased by 0.1 MPa every 1 hour, with the highest pressure controlled at 0.3 MPa. The soaking environment temperature is maintained at a normal temperature range of 25-35°C. The total soaking time is adjusted according to the size of the lithium battery, with small lithium batteries soaked for 2-3 hours and large lithium batteries soaked for 4-6 hours.

[0038] By gradually expanding the small gaps between the lithium battery shell, the battery cell, and the battery cells through gradient pressure, the reaction solution can penetrate more quickly and uniformly to the bonding interface, solving the problem of incomplete degradation of local adhesives caused by uneven solution penetration in the prior art. At the same time, it avoids the impact damage of high pressure to the structure of the lithium battery, which is different from the single mode of traditional normal pressure soaking or high-pressure forced penetration.

[0039] Dynamic monitoring during soaking: During the soaking process, the concentration change of the reaction solution is monitored in real time by an online refractometer. When the concentration of the reaction solution decreases by more than 10% of the initial concentration, the corresponding amount of weakly basic compound and deionized water is automatically supplemented to maintain the reaction solution concentration within the effective range of 5%-15%. At the same time, the pH value of the reaction solution is monitored in real time by a pH meter to ensure that the pH value is maintained between 8.5 and 10.5, avoiding the weakening of the alkalinity of the reaction solution due to the reaction, which affects the degradation effect. Unlike the static soaking method in the prior art, the reaction system is precisely controlled, ensuring the consistency and stability of the adhesive degradation, and improving the subsequent disassembly efficiency.

[0040] III. Mechanical stripping and separation

[0041] Lithium battery removal and drying: After reaching the preset soaking time, the hard-shell lithium battery is removed from the weakly basic pretreatment solution. The residual reaction solution is removed by rinsing the lithium battery surface with deionized water for 1-2 minutes. Then the lithium battery is placed in a well-ventilated and dry place for natural drying. The drying time is 1-2 hours, until there is no obvious water stain on the surface of the lithium battery.

[0042] Shell stripping: Fix the hard-shell lithium battery, and slowly insert a sheet-type stripping tool along the gap between the lithium battery shell and the cell. Adjust the pushing force according to the shell material, apply a pushing force of 50-70 N to the aluminum shell, and a pushing force of 80-100 N to the steel shell. Through the application of uniform pushing force, the preliminary separation of the lithium battery shell and the cell group is realized.

[0043] Inter-cell separation: Place the cell group after stripping the shell on the workbench, and use a precision mechanical tweezer or a small separation clamp. According to the arrangement structure of the cells inside the cell group, start from the edge of the cell group, adjust the pulling force according to the size of the cell, apply a pulling force of 20-30 N to small cells and a pulling force of 40-50 N to large cells. Through the application of uniform pulling force, the separation of the cells is gradually realized. During the separation process, use a 10-20 times high-definition microscope for observation, monitor the separation state in real time, avoid damage to the electrode material due to improper operation, and ensure that the separated cells maintain the complete structure.

[0044] IV. Subsequent processing

[0045] Component cleaning: Clean the lithium battery shell and individual cells obtained by separation. For the lithium battery shell, use deionized water to rinse, and then dry at a temperature of 60-80°C for 30-60 minutes. The dried shell can be used for subsequent recycling and reprocessing. For individual cells, remove residual adhesive debris and other impurities by wiping the surface with anhydrous ethanol, and then dry in a well-ventilated environment at room temperature for 30-60 minutes. The dried cells are ready for use or for subsequent electrode material recovery operations.

[0046] Solution recovery treatment: Collect the used reaction solution during the soaking process, remove impurity particles in the solution through a filtration device, and then detect the concentration of the filtered reaction solution. If the solution concentration is still within the effective range of 5%-15%, adjust the solution to the preset concentration (5%-15% weak alkaline pretreatment solution) by supplementing an appropriate amount of weak alkaline compound and deionized water, and then recycle it, with the recycling frequency not exceeding 5 times. If the solution concentration is too low or has deteriorated, neutralize the reaction solution by adjusting the pH value to 6-9, and then discharge it according to environmental protection requirements or entrust a professional agency to handle it.

[0047] By adding a fluoride ion complexing agent to the weak alkaline pretreatment solution, the fluoride ion complexing agent forms a stable complex with the fluoride ion generated by the degradation of the binder, breaks the reaction equilibrium and accelerates the breaking of the binder molecular chain. Not only does it solve the problem of slow reaction rate and residual product in traditional chemical degradation, but it also avoids secondary pollution caused by the deposition of fluoride ions on the surface of battery components. At the same time, the fluoride ion complexing agent does not react with the metal shell and electrode materials, ensuring the selectivity of the treatment process.

[0048] By using gradient pressure soaking, the initial pressure is maintained at atmospheric pressure and then gradually increased to the preset value, which can gradually expand the small gap between the battery shell and the battery cell, and promote the reaction solution to penetrate more quickly and uniformly to the bonding interface. This effectively solves the problem of incomplete degradation of local binders caused by uneven solution penetration in existing technologies, while avoiding damage to the battery structure caused by high pressure.

[0049] By dynamically monitoring and accurately controlling the reaction solution during soaking with an online refractometer and pH meter, the concentration of the solution is automatically replenished when the concentration drops below a certain threshold, ensuring that the pH value is within the appropriate range. This achieves precise control of the reaction system, ensuring the consistency and stability of the binder degradation, and significantly improving the subsequent disassembly efficiency.

[0050] By using the combination of "chemical pretreatment + mild mechanical peeling", the shell and battery cell can be efficiently separated at room temperature, which greatly reduces the energy consumption compared to existing high-temperature pyrolysis technology, and avoids the oxidation damage of the electrode material caused by high temperature. Compared with pure mechanical crushing and sorting technology, the crystal breakage of the electrode material caused by shear force is effectively reduced, and the problem of metal impurities mixed with electrode powder caused by shell fragments is avoided, improving the recycling quality and reuse value of battery components and electrode materials.

[0051] By filtering and detecting the used reaction solution, recycling it within the effective concentration range and controlling the reasonable recycling times, the raw material consumption and processing cost are reduced, and the waste liquid discharge is also reduced. The failed solution is neutralized to neutral before being discharged or processed, which meets the environmental protection requirements and helps the green and sustainable development of the lithium battery recycling industry.

[0052] In addition, the method for chemical degradation pretreatment of the binder before disassembling the lithium battery includes the following embodiments:

[0053] Embodiment 1

[0054] Preparation of the pretreatment solution: Select sodium bicarbonate as a weak alkaline compound, add deionized water, stir at a speed of 300 r / min for 15 minutes, and prepare a weak alkaline pretreatment solution with a mass concentration of 5%; add 0.1% of calcium disodium ethylenediaminetetraacetate (fluoride complexing agent) to the solution, stir until completely dissolved, and obtain the reaction solution.

[0055] Lithium battery pretreatment operation: Select 18650 type cylindrical hard shell lithium batteries (aluminum shell), wipe the surface in the same direction with a dust-free cloth dipped in anhydrous ethanol to remove dust and oil stains; discharge the battery at a rate of 0.1C until the voltage drops to 0.5V; evenly apply silicon rubber sealant to the tab area (the thickness is controlled to be 1mm), and stand for 2 hours at room temperature until the sealant is completely cured; immerse the sealed battery in the reaction solution, control the liquid level to be 5mm higher than the top of the battery, maintain 1 standard atmosphere for the first 1 hour, then increase the pressure by 0.1MPa every 1 hour until the pressure reaches 0.3MPa, and continue to soak for 2 hours at 25°C constant temperature environment; During the soaking process, the concentration of the reaction solution is monitored in real time with an online refractometer, and when the concentration decreases by more than 10% of the initial concentration, immediately supplement the corresponding amount of sodium bicarbonate and deionized water, and at the same time, monitor the pH value of the solution in real time with a pH meter, and maintain the pH value at 8.5.

[0056] Mechanical peeling and separation: After the soaking time is reached, take out the battery with an alkali-resistant plastic tweezers, and slowly rinse the surface of the battery with deionized water for 1 minute to remove residual solution; place the battery in a well-ventilated area and dry naturally for 1 hour until there is no obvious water stain on the surface; use a pneumatic clamp with a flexible buffer layer to fix the battery, adjust the clamping force to 80N to ensure that the battery is stable and does not deform; select a stainless steel sheet with a thickness of 0.2mm as the peeling tool, slowly insert the tool head into the gap between the battery shell and the cell group, control the insertion depth to be 2mm, apply a uniform pushing force of 50N, and realize the preliminary separation of the shell and the cell group; use a precision mechanical tweezers with a rubber sleeve at the tip to clamp a single cell from the edge of the cell group, apply a uniform pulling force of 20N, and gradually separate the cell. During the separation process, use a 10x high-definition optical microscope to observe the whole process and monitor the separation state in real time.

[0057] Subsequent treatment: the separated battery shell is washed with deionized water for 2 minutes, placed in a drying oven at 60°C for 30 minutes, taken out and cooled to room temperature, and then recovered; the cell is wiped with a dust-free cloth dipped in anhydrous ethanol to remove residual adhesive debris, and then dried at room temperature in a well-ventilated environment for 30 minutes; the soaked reaction solution is collected, filtered through a polytetrafluoroethylene (PTFE) filter membrane with a pore size of 0.22 μm to remove impurity particles in the solution; the concentration of the filtered solution is detected by acid-base titration method, and the detection result is 5%, and then appropriate amount of sodium bicarbonate and deionized water is added to the solution, stirred uniformly, and then detected again to adjust the concentration to 5% for the next batch of battery pretreatment (counted as the first cycle).

[0058] Example 2

[0059] Preparation of pretreatment solution: sodium carbonate is selected as a weak alkaline compound, added to deionized water, stirred at a rate of 400 r / min for 20 minutes, and continuously observed during stirring until the sodium carbonate is completely dissolved to prepare a weak alkaline pretreatment solution with a mass concentration of 10%; 0.3% of calcium disodium ethylenediaminetetraacetate is added to the solution, and stirring is continued for 5 minutes to obtain a reaction solution.

[0060] Lithium battery pretreatment operation: 21700 type cylindrical hard shell lithium battery (aluminum shell) is selected, the surface is wiped with a dust-free cloth dipped in anhydrous ethanol to ensure no impurities are left; the battery is discharged at a discharge rate of 0.15C until the voltage drops to 0.4V; the tab part is coated with silicone sealant (the coating thickness is controlled to be 1.5mm), and the sealant is cured at room temperature for 3 hours; the battery is immersed in the reaction solution, the liquid level is controlled to be 7mm higher than the top end of the battery, 1 standard atmosphere is maintained for the first 1 hour, and then the pressure is increased by 0.1MPa every 1 hour to 0.3MPa, and the battery is soaked at 30°C for 3 hours; the concentration of the solution is monitored in real time by an online refractometer during soaking, and when the concentration decreases by more than 10% of the initial concentration, sodium carbonate and deionized water are supplemented, and the pH value of the solution is monitored by a pH meter, and the pH value is maintained at 9.5.

[0061] Mechanical peeling separation: the battery is taken out and washed with deionized water for 1.5 minutes, and then naturally dried in a well-ventilated and dry place for 1.5 hours; the battery is fixed by an adjustable electric chuck, the clamping force is adjusted to 100N, a stainless steel sheet with a thickness of 0.3mm is selected as the peeling tool, the tool is inserted into the gap between the shell and the cell group by 3mm, and a uniform pushing force of 60N is applied to separate the shell; a small separation clamp is used to apply a uniform pulling force of 25N to the edge of the cell group to separate the cell, and a 15 times high-definition microscope is used to observe in real time during the separation process.

[0062] Subsequent treatment: After the battery shell was washed with deionized water, it was placed in a 70°C drying oven for 40 minutes; the battery cell was wiped with anhydrous ethanol and then dried at room temperature for 40 minutes; the reaction solution was collected, filtered through a 0.22 μm PTFE filter membrane, and the concentration was detected to be 9% by acid-base titration method; the solution was supplemented with appropriate amount of sodium carbonate and deionized water, and the concentration was adjusted to 10% for the next batch of processing (counted as the 3rd cycle).

[0063] Example 3

[0064] Preparation of pretreatment solution: Sodium bicarbonate and sodium carbonate were selected as weak alkaline compounds in a mass ratio of 1:1, added to deionized water, and stirred at a speed of 450 r / min for 25 minutes to prepare a weak alkaline pretreatment solution with a mass concentration of 12%; 0.4% of calcium disodium ethylenediaminetetraacetate was added to the solution and stirred until completely mixed to obtain a reaction solution.

[0065] Pretreatment operation of lithium battery: A square hard shell lithium battery (steel shell) with a size of 300 mm x 150 mm x 15 mm was selected, and the surface was wiped with a dust-free cloth dipped in anhydrous ethanol; discharged at a rate of 0.18C to a voltage of 0.3V; the tab part was coated with silicone sealant (the coating thickness was controlled to be 1.8 mm), and the sealant was cured at room temperature for 3.5 hours; the battery was immersed in the reaction solution, the liquid level was controlled to be 8 mm higher than the top end of the battery, 1 standard atmosphere was maintained for the first 1 hour, and then the pressure was increased by 0.1 MPa every 1 hour to 0.3 MPa, and the immersion was carried out at 32°C for 4.5 hours; the concentration was monitored by an online refractometer during immersion, and when it decreased by more than 10% of the initial value, the mixed weak alkaline compound and deionized water were supplemented, and the pH value of the solution was monitored by a pH meter to maintain the pH value at 10.0.

[0066] Mechanical peeling and separation: The battery was washed with deionized water for 1.8 minutes and dried for 1.8 hours; the battery was fixed with a pneumatic clamp with a flexible buffer layer (clamping force 110N), a 0.4 mm thick stainless steel sheet peeling tool was selected, inserted 4 mm along the gap between the shell and the cell group, and a 90N pushing force was applied to separate the shell; a small separation clamp was used to apply a 45N pulling force to the edge of the cell group to separate the cells, and a 18 times high-definition microscope was used for real-time observation.

[0067] Subsequent treatment: After the battery shell was washed with deionized water, it was placed in a 75°C drying oven for 50 minutes; the battery cell was wiped with anhydrous ethanol and then dried at room temperature for 50 minutes; the reaction solution was collected, filtered through a 0.22 μm PTFE filter membrane, and the concentration was detected to be 11%, the mixed weak alkaline compound and deionized water were supplemented, and the concentration was adjusted to 12% for the next batch of processing (counted as the 4th cycle).

[0068] Example 4

[0069] Preparation of the pretreatment solution: Select sodium carbonate as a weak alkaline compound, add deionized water, stir at a speed of 480 r / min for 28 minutes, and prepare a weak alkaline pretreatment solution with a mass concentration of 14%; add 0.45% of calcium disodium ethylenediaminetetraacetate to the solution, stir until uniform, and obtain a reaction solution.

[0070] Pretreatment operation of the lithium battery: Select a square hard-shell lithium battery (steel shell) with a size of 400 mm x 180 mm x 18 mm, wipe the surface with a dust-free cloth dipped in anhydrous ethanol; discharge at a rate of 0.19C until the voltage drops to 0.2V; apply a thickness of 1.9 mm of silicone sealant to the tab area, and stand at room temperature for 3.8 hours until the sealant solidifies; immerse the battery in the reaction solution, control the liquid level to be 9 mm higher than the top end of the battery, maintain 1 atm for the first 1 hour, and then increase the pressure by 0.1 MPa every 1 hour to 0.3 MPa, immerse for 5.5 hours in a constant temperature environment of 34°C; monitor the concentration during immersion with an online refractometer, and supplement sodium carbonate and deionized water when the concentration drops by more than 10% of the initial value; monitor the pH value of the solution with a pH meter, and maintain the pH value at 10.3.

[0071] Mechanical peeling and separation: Take out the battery and rinse it with deionized water for 1.9 minutes, and dry it in a ventilated environment for 1.9 hours; fix the battery with an adjustable electric chuck (clamping force 115 N), select a 0.45 mm thick stainless steel sheet peeling tool, insert it 4.5 mm along the gap between the shell and the cell, and apply a 95 N pushing force to separate the shell; use a precision mechanical tweezer to apply a 48 N pulling force to the edge of the cell group to separate the cells, and observe in real time with a 19 times high-definition microscope.

[0072] Subsequent treatment: After rinsing the shell with deionized water, dry it in a 78°C drying oven for 55 minutes; wipe the cell with anhydrous ethanol, and dry it in a ventilated environment at room temperature for 55 minutes; collect the reaction solution, filter it through a 0.22 μm PTFE filter membrane, detect the concentration to be 13%, supplement sodium carbonate and deionized water, and adjust the concentration to 14% for use in the next batch of treatment (counted as the 5th cycle).

[0073] Example 5

[0074] Preparation of the pretreatment solution: Select sodium carbonate as a weak alkaline compound, add deionized water, stir at a speed of 500 r / min for 30 minutes to ensure complete dissolution of the sodium carbonate, and prepare a weak alkaline pretreatment solution with a mass concentration of 15%; add 0.5% of calcium disodium ethylenediaminetetraacetate to the solution, stir for 5 minutes until mixed uniformly, and obtain a reaction solution.

[0075] Lithium battery pretreatment operation: select the size of 500 mm x 200 mm x 20 mm square hard shell lithium battery (steel shell), wipe the surface with dust-free cloth dipped in anhydrous ethanol; discharge at a rate of 0.2C to voltage drop to 0.1V; use silicone sealant to smear the tab part (the thickness is controlled to be 2mm), and stand at room temperature for 4 hours until the sealant is completely cured; immerse the battery in the reaction solution, control the liquid level to be higher than the top end of the battery by 10mm, maintain 1 standard atmosphere for the first 1 hour, and then increase the pressure by 0.1MPa every 1 hour to 0.3MPa, immerse for 6 hours in a constant temperature environment of 35℃; monitor the concentration with an online refractometer during immersion, and when the decrease exceeds 10% of the initial value, supplement sodium carbonate and deionized water, and monitor the pH value of the solution with a pH meter, and maintain the pH value at 10.5.

[0076] Mechanical peeling separation: take out the battery and rinse with deionized water for 2 minutes, and dry for 2 hours; use a pneumatic clamp with a flexible buffer layer to fix the battery (clamping force 120N), select a 0.5mm thick stainless steel sheet peeling tool, insert 5mm along the gap between the shell and the cell, and apply a uniform pushing force of 100N to separate the shell; use a small separation clamp to apply a uniform pulling force of 50N to the edge of the cell group to separate the cells, and use a 20x high-definition microscope to observe in real time.

[0077] Subsequent treatment: after washing the shell with deionized water, dry it in an 80℃ drying oven for 60 minutes; wipe the cell with anhydrous ethanol and dry it at room temperature for 60 minutes; collect the reaction solution, filter it through a 0.22μm PTFE filter membrane, and detect the concentration by acid-base titration method to be 12% (lower than the effective range of 15%); slowly add 15% mass concentration dilute hydrochloric acid to the solution while stirring, and monitor the pH value in real time with a pH meter; when the pH value of the solution is adjusted to 9, stop adding acid, and entrust a professional institution with hazardous waste treatment qualification to conduct compliant treatment.

Claims

1. A method for chemical degradation pretreatment of binders before disassembly of lithium batteries, characterized in that: The following steps are included: S1. Preparation of pretreatment solution: Add the weakly alkaline compound to deionized water and mix to prepare a weakly alkaline pretreatment solution with a mass concentration of 5%-15%. Then add a fluoride ion complexing agent with a mass concentration of 0.1%-0.5% to the weakly alkaline pretreatment solution and stir to mix evenly to obtain a reaction solution. S2. Lithium battery pretreatment: Clean and discharge the surface of the lithium battery, then apply silicone rubber sealant to the battery tabs with a thickness of 1-2 mm, and let it stand for 2-4 hours until the silicone rubber sealant cures to complete the sealing treatment of the lithium battery; immerse the sealed lithium battery in the reaction solution, and soak it in a gradient pressure method at a temperature of 25-35℃, while monitoring and adjusting the pH value of the reaction solution to maintain the pH value at 8.5-10.5; S3. Mechanical peeling and separation: The soaked lithium battery is taken out and rinsed, dried and fixed in sequence; then, a pushing force is applied in the gap between the lithium battery casing and the cell assembly to separate the casing, and then a pulling force is applied from the edge of the cell assembly to separate the cells and obtain the cells; S4. Post-processing: Rinse the separated lithium battery casing with deionized water, then dry it at a temperature of 60-80℃ for 30-60 minutes; wipe the battery cell with anhydrous ethanol, then dry it under normal temperature and ventilation conditions for 30-60 minutes; filter the reaction solution after use, then test the concentration and recycle or neutralize it until the pH value is 6-9 before compliant discharge.

2. The method for chemical degradation pretreatment of binders before disassembly of lithium batteries according to claim 1, characterized in that: In S1, the weakly basic compound is one or both of sodium bicarbonate and sodium carbonate, and the fluoride ion complexing agent is calcium disodium ethylenediaminetetraacetate.

3. The method for chemical degradation pretreatment of binders before disassembly of lithium batteries according to claim 1, characterized in that: In step S1, the weakly alkaline compound and deionized water are mixed by adding them while stirring, with a stirring rate of 300-500 r / min and a stirring time of 15-30 minutes.

4. The method for chemical degradation pretreatment of binders before disassembly of lithium batteries according to claim 1, characterized in that: In step S2, the lithium battery is discharged at a discharge rate of 0.1C-0.2C until the voltage of the lithium battery is ≤0.5V.

5. The method for chemical degradation pretreatment of binders before disassembly of lithium batteries according to claim 1, characterized in that: In step S2, the sealed lithium battery is completely immersed in the reaction solution, and the liquid level of the reaction solution is controlled to be 5-10 mm higher than the top of the lithium battery.

6. The method for chemical degradation pretreatment of binders before disassembly of lithium batteries according to claim 1, characterized in that: In S2, the specific operation of gradient pressure immersion is as follows: maintain normal pressure for the first hour, and then increase the pressure by 0.1 MPa every hour, with the maximum pressure controlled at 0.3 MPa.

7. The method for chemical degradation pretreatment of binders before disassembly of lithium batteries according to claim 1, characterized in that: In step S3, when separating the outer casing, if the lithium battery is made of aluminum, a uniform thrust of 50-70N is applied; if it is made of steel, a uniform thrust of 80-100N is applied.

8. The method for chemical degradation pretreatment of binders before disassembly of lithium batteries according to claim 1, characterized in that: In S3, when separating the battery cells, precision mechanical tweezers or a small separation clamp are used.

9. The method for chemical degradation pretreatment of binders before disassembly of lithium batteries according to claim 1, characterized in that: In step S3, a 10-20x high-definition microscope is used for full-process observation and real-time monitoring of the separation status.

10. The method for chemical degradation pretreatment of binders before disassembly of lithium batteries according to claim 1, characterized in that: In step S4, after concentration detection, if the solution concentration is within the effective range of 5%-15%, the solution is adjusted to the preset concentration by adding a weak alkaline compound and deionized water and then recycled, with the number of cycles not exceeding 5. If the solution concentration is too low or has deteriorated, the reaction solution is neutralized and discharged.

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