A solvent-based disassembly method for CTP battery pack

Abstract

This invention discloses a solvent-based non-destructive disassembly method for CTP battery packs, belonging to the field of battery pack disassembly. The solvent-based non-destructive disassembly method for CTP battery packs comprises the following steps: Step 1, safety pretreatment; discharging the CTP battery pack until the cell voltage is within a safe range, allowing it to stand for a period of time before disassembly; Step 2, module busbar cutting; Step 3, casing cleaning; Step 4, battery pack solvent immersion; adding 0.5%-2% by mass of an environmentally friendly anti-volatile additive to the solvent, then pouring it into the module, maintaining sufficient contact with the module structural adhesive to soften or lose its adhesive strength; Step 5, individual cell separation; Step 6, cleaning and cell post-treatment; removing the blue film from the individual cells and cleaning the separated individual cells. This invention fundamentally solves the industry pain points of traditional CTP battery packs, such as the difficulty of manual adhesive removal during disassembly, the risk of cell damage, high safety risks, and low product recycling rate.

Description

Technical Field

[0001] This invention relates to the field of battery pack disassembly technology, and in particular to a non-destructive disassembly method for CTP battery packs based on solvent disassembly. Background Technology

[0002] Currently, electric vehicle battery technology is undergoing rapid evolution. Cell-to-Pack (CTP) technology, through its simplified structure, has become a key path to improve battery pack energy density and range. Compared to the traditional cell-module-battery pack, CTP battery packs offer higher space utilization, energy density, simplified structure, and higher production efficiency. It is a very successful and mainstream technology route in the current development of power battery technology and is widely adopted and promoted in the industry. However, due to the special structure of CTP, which uses high-strength structural adhesive to bond the cells to the casing and liquid cooling plate, existing manual methods for removing structural adhesive and disassembling cells are not only difficult to disassemble but also prone to material damage and safety risks, resulting in low product recycling rates. Therefore, there is a need for a gentle, safe, and highly recyclable CTP battery pack disassembly method. Summary of the Invention

[0003] The purpose of this invention is to solve the problems existing in the prior art by proposing a non-destructive disassembly method for CTP battery packs based on solvent disassembly.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A non-destructive disassembly method for CTP battery packs based on solvent disassembly, comprising the following steps: Step 1, Safety Pre-processing; Discharge the CTP battery pack until the cell voltage is within a safe range, then remove it after letting it stand for a period of time. Step 2: Cut the module busbar; Step 3: Clean the box; Step 4: Solvent impregnation of the battery pack; Add 0.5%-2% by mass of an environmentally friendly anti-volatile additive to the solvent, then pour it into the module and keep it in contact with the module structural adhesive for a sufficient time to soften or lose its adhesiveness. Step 5: Separate individual battery cells; Step Six: Cleaning and Post-processing of Battery Cells; Remove the blue film from the individual battery cells and clean the separated individual battery cells.

[0005] Preferably, in step one, the settling time is 15-30 minutes. When dismantling, the low-voltage wiring harness must be disconnected first and then the high-voltage circuit must be disconnected. The CTP battery pack is then checked for sealing by visual inspection combined with a pressure test at 0.05-0.1MPa for 5 minutes to ensure there is no pressure drop, thus ensuring that there are no leaks and that the pack can contain solvent.

[0006] Preferably, in step two, after disassembly, the position of the busbar inside the CTP battery pack is exposed. The busbar is separated using an aluminum cutting machine. When cutting the busbar with double seams, the cutting depth should not exceed 2mm. Subsequently, diagonal pliers are used to tear it apart. During the cutting and use of diagonal pliers, attention should be paid to the spacing between adjacent cells to avoid simultaneous contact and arcing.

[0007] Preferably, in step three, an industrial vacuum cleaner with a negative pressure value ≥0.08MPa is used to remove aluminum shavings generated during the manifold cutting. Aluminum shavings that are difficult to remove from the CTP battery pack housing and module gaps are removed using adhesive bags and insulating rods.

[0008] Preferably, in step four, the solvent is selected as an ester-ketone composite organic solvent for polyol-isocyanate type structural adhesives, and the composite organic solvent is a mixture of ethyl acetate and acetone in a volume ratio of 4:6. The anti-volatile additive is one of tributyl citrate and dodecyl alcohol ester, or a mixture of both in a mass ratio of 1:1. The mixture is stirred evenly to obtain the impregnation solution.

[0009] Further, in step four, the operator wears rubber gloves and uses a beaker to pour the wetting solution into the gaps at the edge of the box, until the level of the wetting solution near the end of the module exceeds the structural adhesive by 2-3 cm. The wetting solution is injected into the module gaps in the middle of the box beams using an injection device until the liquid level is level with the box beams. During the injection process, a negative pressure of 0.03-0.05 MPa is applied to the inside of the battery pack for osmosis treatment, and the ambient temperature is maintained at 25±1℃. Subsequently, the solution is replenished every 5 hours. Then, the upper surface of the battery pack is sealed with a stretch film to prevent solvent evaporation, allowing the wetting solution to fully contact and immerse the structural adhesive for 24-48 hours, so that the structural adhesive softens or loses its adhesive strength. After immersion, the remaining wetting solution is collected and pretreated by coarse filtration through a 100-200 mesh filter and fine filtration through a 0.22μm precision filter membrane.

[0010] Furthermore, the mixing and stirring of the impregnation solution adopts magnetic stirring at a speed of 200-300 r / min and a stirring time of 5-10 min to ensure that the anti-volatile additive and the composite organic solvent are fully mixed. The injection device is a syringe-type injection pump with an injection flow rate of 5-10 mL / min to avoid splashing of the impregnation solution and contaminating the battery cell.

[0011] Preferably, in step five, the wedge-shaped tool is placed vertically between the two battery cells, and the wedge-shaped tool is slowly and vertically inserted between the two battery cells using a rubber hammer. After a gap appears between the battery cells, the battery cells are clamped out, and then the above operation is repeated to separate the remaining battery cells.

[0012] Preferably, in step six, a plastic shovel is used parallel to the surface of the box to remove residual adhesive inside the battery pack box. After removing particles from the surface of the box with an industrial vacuum cleaner, the residual adhesive on the surface of the box is wiped with a lint-free cloth dipped in anhydrous ethanol. After cleaning, the box is left to stand at room temperature and pressure for 1 hour. For the separated individual battery cells, the blue film on the battery cell is first removed, and then the adhesive residue and stains on the surface of the battery cell are wiped with a lint-free cloth dipped in isopropyl alcohol. Subsequently, the battery cells are subjected to appearance inspection and performance testing.

[0013] Furthermore, the appearance inspection includes checking whether there are dents, scratches, or deformations in the aluminum shell of the battery cell, whether the explosion-proof valve is intact and undamaged, and whether the QR code of the battery cell is clear and identifiable; the performance inspection includes capacity retention rate, internal resistance, and cycle life testing; the battery cells are classified according to the test results, and the battery cells with a capacity retention rate ≥80% and internal resistance ≤100mΩ are qualified battery cells, which are re-coated with blue film for secondary use, and the remaining battery cells are recycled and regenerated, and the positive and negative electrodes are kept isolated from each other during the storage of the battery cells to avoid short circuits.

[0014] Compared with the prior art, the present invention provides a non-destructive disassembly method for CTP battery packs based on solvent disassembly, which has the following beneficial effects: 1. This solvent-based non-destructive disassembly method for CTP battery packs selects specific solvents that can effectively swell, soften, or degrade the structural adhesive inside the CTP battery pack, thereby achieving separation with extremely low damage at room temperature, further improving the safety of disassembly and the cell integrity rate. The molecular polarity and chemical properties of organic solvents are "similar" to the polymer molecules of structural adhesives. Through this "similarity," the solvent molecules begin to penetrate into the gaps of the three-dimensional cross-linked network of the cured adhesive. After entering, the solvent molecules surround and enclose the polymer chains of the adhesive. Due to their similar properties, the interaction forces between the polymer chains are weakened, and the gaps between the chain segments become larger, causing the entire adhesive to expand and soften, thereby achieving a dissolution effect.

[0015] 2. This solvent-based non-destructive disassembly method for CTP battery packs utilizes the synergistic effect of ethyl acetate and acetone. It leverages the strong permeability of acetone to rapidly soften the adhesive layer, while the moderate evaporation rate of ethyl acetate maintains the long-lasting effectiveness of the wetting solution. Simultaneously, the viscosity of the composite solvent is moderate, preventing blockage of the cell gaps due to excessive viscosity and rapid loss due to excessively low viscosity, perfectly matching the long-lasting wetting requirements of 24-48 hours. Attached Figure Description

[0016] Figure 1 This is a schematic flowchart of a non-destructive disassembly method for CTP battery packs based on solvent disassembly proposed in this invention. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0018] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0019] Example 1: Refer to Figure 1 A non-destructive disassembly method for CTP battery packs based on solvent disassembly, comprising the following steps: Step 1, Safety Pre-processing; Discharge the CTP battery pack until the cell voltage is within a safe range, and then remove it after a period of rest. Specifically, discharge the CTP battery pack using a constant current discharge method of 0.1-0.2C until the cell voltage is within a safe range of 0.0-0.5V, and let it stand for 30 minutes after discharge. Operators wearing insulating gloves with a withstand voltage of ≥500V should use a reverse-rotating gun with a torque of 12N·m to remove the battery pack cover. Two people should work together to remove the cover and place it in a designated area. When removing electrical components, disconnect the low-voltage harness first, and then disconnect the high-voltage return wire. When removing the FPC, first press the corresponding clip of the data acquisition line interface to remove the data acquisition line, then use diagonal pliers with a blade thickness ≤1.5mm to remove the nickel sheet and remove the FPC; then use high-temperature resistant polyimide tape with a width of 20mm and a temperature resistance of 120℃ or higher to fully cover and protect the cell explosion-proof valve and cell QR code, leaving no exposed areas; finally, conduct a sealing check on the battery pack by visual inspection combined with holding the pressure at 0.1MPa for 5 minutes and a pressure drop ≤0.005MPa to ensure that there are no leaks and that the pack can accommodate solvents.

[0020] Step 2: Cut the module busbar; After disassembly, the busbars inside the CTP battery pack were exposed. An aluminum cutting machine with a speed of 3000 r / min and a cutting blade thickness of 0.8 mm was used to make double-slit cuts on the exposed busbars. The distance between the double slits was 5 mm, and the cutting depth did not exceed 2 mm. After cutting, the busbars were torn apart with diagonal pliers with a blade thickness of ≤1.5 mm. During the cutting and tearing process, the distance between the operating tools and the adjacent cells was controlled to be ≥5 mm to avoid contact with the cells and causing sparking. The operating area was kept free of flammable debris.

[0021] Step 3: Clean the box; An industrial vacuum cleaner with a negative pressure of ≥0.08MPa and a nozzle diameter of 10mm is used to remove aluminum shavings from the manifold cutting area, with the nozzle moving at a speed of 5cm / s. For aluminum shavings that are difficult to remove from the CTP battery pack housing and module gaps, a 300cP adhesive bag is used in conjunction with an 8mm diameter insulating rod to remove them. After cleaning, the battery pack must meet the standard of having no visible aluminum shavings inside. After double inspection and confirmation of compliance, the process proceeds to the next step.

[0022] Step 4: Solvent impregnation of the battery pack; Specifically, the solvent selected is an ester-ketone composite organic solvent for polyol-isocyanate type structural adhesives, and this composite organic solvent is a mixture of ethyl acetate and acetone in a 4:6 volume ratio, which has a significant swelling or softening ability for the structural adhesive in the CTP battery pack. 0.5% by mass of an environmentally friendly anti-volatile additive is added to the composite organic solvent. The anti-volatile additive is one of tributyl citrate and dodecyl alcohol ester, or a mixture of both in a 1:1 mass ratio. The mixture is stirred at 200 rpm for 5 minutes using a magnetic stirrer to obtain a uniform wetting solution. The operator, wearing solvent-resistant rubber gloves, pours the wetting solution into the gaps at the edge of the housing, ensuring that the liquid level near the housing end of the module exceeds the structural adhesive by 2 cm. At the module intervals in the middle of the housing beams, the wetting solution is injected using a 20 mL syringe pump with an injection flow rate of 5 mL / min until the liquid level is equal to the housing level. The crossbeams are kept level. During the injection process, a negative pressure of 0.03 MPa is applied to the inside of the battery pack for 10 minutes to help the wetting liquid fill the dead corners of the adhesive layer between the cells. After the injection is completed, the liquid is replenished every 5 hours, with a single replenishment volume of 50 mL, until the original set liquid level is reached. At the same time, a PE wrapping film with a thickness of 0.02 mm is tightly wrapped and sealed on the upper surface of the battery pack in two layers to prevent solvent evaporation. The ambient temperature is maintained at 25±1℃ and the humidity at 40%, allowing the wetting liquid to fully contact and wet the structural adhesive for 24 hours, so that the structural adhesive softens or loses its adhesive strength. After wetting, the remaining wetting liquid at the bottom of the battery pack and in the crossbeams on the side of the box is collected by siphon method. The collected wetting liquid is then pre-treated by passing it through a 150-mesh metal filter for coarse filtration and a 0.22 μm polytetrafluoroethylene precision filter membrane at a filtration pressure of 0.1 MPa for easy reuse.

[0023] Among them, the polarity of ethyl acetate molecules is highly matched with the three-dimensional cross-linked network polymer of polyol-isocyanate type structural adhesive, achieving adhesive layer penetration through similar dissolution, gently swelling the adhesive layer without damaging the structure of the battery cell aluminum shell, blue film, etc., meeting the core requirements of non-destructive disassembly; and the evaporation rate is moderate, which can balance the solvent penetration rate and evaporation loss when compounded with acetone, avoiding the problem of excessively fast penetration but high evaporation when used alone; it is environmentally friendly and low in toxicity, has good industrial workability, no strong irritating odor, and meets the environmental protection operation standards of factory workshops; it is completely miscible with anti-volatile additives such as tributyl citrate and dodecyl alcohol ester, and there is no layering or precipitation after adding additives, ensuring the uniformity of the wetting solution; it is easily soluble in anhydrous ethanol and isopropanol, and the solvent remaining on the surface of the box / battery cell after disassembly can be quickly wiped away by cleaning reagents without residue.

[0024] Acetone exhibits strong permeability to polyol-isocyanate type structural adhesives, rapidly penetrating the tiny cross-linking gaps in the adhesive layer, weakening the interaction forces between polymer chains, significantly improving the softening efficiency of the structural adhesive, and shortening the 24-48h impregnation cycle. Furthermore, its low boiling point and good fluidity allow it to quickly fill narrow areas such as gaps between battery cells and dead corners in the adhesive layer. When combined with negative pressure permeation treatment, it can further enhance the overall contactability of the solvent. Secondly, when compounded with ethyl acetate, it can adjust the swelling capacity of the composite solvent; a 4:6 volume ratio ensures strong permeation while avoiding a sudden drop in impregnation concentration due to excessively rapid evaporation of acetone alone. It has no electrochemical activity on the battery cell and does not react with components such as the battery cell aluminum shell, explosion-proof valve, and QR code, thus preventing problems such as short circuits and label corrosion. It is easily recyclable; after coarse and fine filtration, it can be reused, and its swelling performance does not significantly decrease after recycling, reducing the cost of dismantling consumables.

[0025] The synergistic effect of ethyl acetate and acetone is achieved by utilizing the strong penetrability of acetone to quickly soften the adhesive layer, while the moderate evaporation rate of ethyl acetate maintains the long-lasting effect of the wetting solution. At the same time, the viscosity of the composite solvent is moderate, which will not clog the gap between the battery cells due to excessive viscosity, nor will it cause rapid loss due to excessive viscosity, perfectly matching the long-lasting wetting requirements of 24-48h.

[0026] Step 5: Separate individual battery cells; Specifically, a non-metallic wedge tool made of PTFE or nylon, with a tip angle of 30-45°, a thickness of 2mm, and a length of 150mm, is used. First, the wedge tool is vertically inserted into the foam gap between the battery cell and the end plate, with an insertion depth of ≤3cm, to separate the top foam from the end plate. After separation, the end plate is torn out using diagonal pliers. If the end plate breaks in the middle, a 3-4mm diameter iron hook with a rounded tip and a radius ≥2mm is inserted into the gap to hook out the bottom end plate. The hook should move freely within the gap before proceeding. Finally, the wedge tool is placed vertically between the two battery cells. Use a 0.2kg rubber hammer to gently strike the top of the wedge-shaped tool vertically downwards, allowing the wedge-shaped tool to slowly and vertically enter between the two battery cells. After a gap of ≥5mm appears between the battery cells, pry the wedge-shaped tool back and forth at an amplitude of 5-10mm and a frequency of 10-15 times / min to widen the separation gap between the adhesive layer and the battery cell and allow the wetting liquid to further penetrate into the unsoftened adhesive layer. Then, use a silicone-coated non-metallic battery cell clamp to clamp out the battery cell with a pulling force of 50-80N and a uniform speed of ≤5cm / s, avoiding excessive force that could cause the battery cell to dent. Repeat the above operation to separate and remove the individual battery cells one by one.

[0027] Step Six: Cleaning and Post-processing of Battery Cells; Using a PTFE plastic spatula with a blade thickness of 1-2mm, keep the spatula surface parallel to the bottom of the box and use a pushing force of ≤5N to remove residual adhesive inside the battery pack box. After vacuuming the surface particles of the box with an industrial vacuum cleaner, wipe the surface of the box with a microfiber lint-free cloth with a concentration of ≥99.7% anhydrous ethanol using a microfiber lint-free cloth with a weight of 200-300g / ㎡. After cleaning, let the box stand for 1 hour in an environment with a temperature of 25±2℃ and a humidity of 40%. After standing, inspect the appearance of the box, requiring no residual adhesive and no scratches. For the separated individual battery cells, first remove the blue film from the cell, then wipe the surface of the cell with a microfiber lint-free cloth with a concentration of ≥99.5% isopropyl alcohol to remove adhesive stains and dirt. After air drying for 5 minutes, proceed with further steps. The battery cells undergo appearance and performance testing. Appearance testing involves checking that the aluminum casing has no dents / scratches with a depth ≥0.5mm and a length ≥5mm, no deformation, that the explosion-proof valve is intact and undamaged, and that the cell's QR code is clear, identifiable, and conforms to VPS standards. Performance testing involves checking that the cell's capacity retention rate is ≥80%, internal resistance ≤100mΩ, and capacity retention rate is ≥70% after 500 charge-discharge cycles. Based on the test results, the cells are classified. Cells meeting the above appearance and performance standards are considered qualified and are re-coated with blue film for reuse. The remaining cells are recycled. When storing the cells, ensure that the positive and negative electrodes are isolated to avoid short circuits. The storage environment should be at a temperature of 30℃ and a humidity of ≤75%.

[0028] Example 2: Refer to Figure 1 A non-destructive disassembly method for CTP battery packs based on solvent disassembly, comprising the following steps: Step 1, Safety Pre-processing; Discharge the CTP battery pack until the cell voltage is within a safe range, and then remove it after a period of rest. Specifically, discharge the CTP battery pack using a 0.2C constant current discharge method until the cell voltage is within a safe range of 0.5V, and let it rest for 30 minutes after discharge. Operators wearing insulating gloves with a withstand voltage of ≥500V should use a reverse-rotating gun with a torque of 12N·m to remove the battery pack cover. Two people should work together to remove the cover and place it in a designated area. When removing electrical components, first disconnect the low-voltage harness, then disassemble the high-voltage circuit. When installing the FPC, first press the corresponding clip on the data acquisition line interface to remove the data acquisition line. Then, use diagonal pliers with a blade thickness of ≤1.5mm to remove the nickel sheet and remove the FPC. Next, use high-temperature resistant polyimide tape with a width of 30mm and a temperature resistance of 120℃ or higher to fully cover and protect the cell explosion-proof valve and cell QR code, leaving no exposed areas. Finally, conduct a sealing check on the battery pack by visual inspection combined with holding the pressure at 0.1MPa for 5 minutes and ensuring a pressure drop of ≤0.005MPa to ensure that there are no leaks and that the pack can accommodate solvents.

[0029] Step 2: Cut the module busbar; After disassembly, the busbars inside the CTP battery pack are exposed. An aluminum cutting machine with a speed of 4000 r / min and a cutting blade thickness of 1 mm is used to make double-slit cuts on the exposed busbars. The distance between the double slits is 8 mm, and the cutting depth does not exceed 2 mm. After cutting, the busbars are torn apart with diagonal pliers with a blade thickness of ≤1.5 mm. During the cutting and tearing process, the distance between the operating tools and the adjacent cells is controlled to be ≥5 mm to avoid contact with the cells and causing sparking. The operating area is kept free of flammable debris.

[0030] Step 3: Clean the box; An industrial vacuum cleaner with a negative pressure of ≥0.08MPa and a nozzle diameter of 15mm is used to remove aluminum shavings from the manifold cutting area, with the nozzle moving at a speed of 10cm / s. For aluminum shavings that are difficult to remove from the CTP battery pack housing and module gaps, a 500cP adhesive bag is used in conjunction with a 10mm diameter insulating rod to remove them. After cleaning, the battery pack must meet the standard of having no visible aluminum shavings inside. After double inspection and confirmation of compliance, the process proceeds to the next step.

[0031] Step 4: Solvent impregnation of the battery pack; Specifically, the solvent selected is an ester-ketone composite organic solvent for polyol-isocyanate type structural adhesives, and this composite organic solvent is a mixture of ethyl acetate and acetone in a volume ratio of 4:6, which has a significant swelling or softening ability for the structural adhesive in the CTP battery pack. 2% by mass of an environmentally friendly anti-volatile additive is added to the composite organic solvent. The anti-volatile additive is one of tributyl citrate and dodecyl ester, or a mixture of both in a 1:1 mass ratio. The mixture is stirred at 300 rpm for 10 minutes using a magnetic stirrer to obtain a uniform wetting solution. The operator, wearing solvent-resistant rubber gloves, pours the wetting solution into the gaps at the edge of the housing, ensuring that the liquid level near the housing end of the module exceeds the structural adhesive by 3 cm. At the module intervals in the middle of the housing beams, the wetting solution is injected using a 50 mL syringe pump with an injection flow rate of 10 mL / min until the liquid level is equal to the housing beam level. The process involves applying a negative pressure of 0.05 MPa to the inside of the battery pack during injection for 15 minutes to help the wetting solution fill the dead corners of the adhesive layer between the cells. After injection, the solution is replenished every 5 hours, with a single replenishment volume of 100 mL, until the original set liquid level is reached. At the same time, a PE wrapping film with a thickness of 0.03 mm is tightly wrapped and sealed on the upper surface of the battery pack in 3 layers to prevent solvent evaporation. The ambient temperature is maintained at 25±1℃ and the humidity at 60%, allowing the wetting solution to fully contact and wet the structural adhesive for 48 hours, resulting in the softening or loss of adhesion of the structural adhesive. After wetting, the remaining wetting solution in the bottom of the battery pack and the side beams of the box is collected using a siphon method. The collected wetting solution is then pre-treated by passing it through a 150-mesh metal filter for coarse filtration and a 0.22 μm polytetrafluoroethylene precision filter membrane at a filtration pressure of 0.15 MPa for easy reuse.

[0032] Among them, the polarity of ethyl acetate molecules is highly matched with the three-dimensional cross-linked network polymer of polyol-isocyanate type structural adhesive, achieving adhesive layer penetration through similar dissolution, gently swelling the adhesive layer without damaging the structure of the battery cell aluminum shell, blue film, etc., meeting the core requirements of non-destructive disassembly; and the evaporation rate is moderate, which can balance the solvent penetration rate and evaporation loss when compounded with acetone, avoiding the problem of excessively fast penetration but high evaporation when used alone; it is environmentally friendly and low in toxicity, has good industrial workability, no strong irritating odor, and meets the environmental protection operation standards of factory workshops; it is completely miscible with anti-volatile additives such as tributyl citrate and dodecyl alcohol ester, and there is no layering or precipitation after adding additives, ensuring the uniformity of the wetting solution; it is easily soluble in anhydrous ethanol and isopropanol, and the solvent remaining on the surface of the box / battery cell after disassembly can be quickly wiped away by cleaning reagents without residue.

[0033] Acetone exhibits strong permeability to polyol-isocyanate type structural adhesives, rapidly penetrating the tiny cross-linking gaps in the adhesive layer, weakening the interaction forces between polymer chains, significantly improving the softening efficiency of the structural adhesive, and shortening the 24-48h impregnation cycle. Furthermore, its low boiling point and good fluidity allow it to quickly fill narrow areas such as gaps between battery cells and dead corners in the adhesive layer. When combined with negative pressure permeation treatment, it can further enhance the overall contactability of the solvent. Secondly, when compounded with ethyl acetate, it can adjust the swelling capacity of the composite solvent; a 4:6 volume ratio ensures strong permeation while avoiding a sudden drop in impregnation concentration due to excessively rapid evaporation of acetone alone. It has no electrochemical activity on the battery cell and does not react with components such as the battery cell aluminum shell, explosion-proof valve, and QR code, thus preventing problems such as short circuits and label corrosion. It is easily recyclable; after coarse and fine filtration, it can be reused, and its swelling performance does not significantly decrease after recycling, reducing the cost of dismantling consumables.

[0034] The synergistic effect of ethyl acetate and acetone is achieved by utilizing the strong penetrability of acetone to quickly soften the adhesive layer, while the moderate evaporation rate of ethyl acetate maintains the long-lasting effect of the wetting solution. At the same time, the viscosity of the composite solvent is moderate, which will not clog the gap between the battery cells due to excessive viscosity, nor will it cause rapid loss due to excessive viscosity, perfectly matching the long-lasting wetting requirements of 24-48h.

[0035] Step 5: Separate individual battery cells; Specifically, using a non-metallic wedge tool made of PTFE or nylon, with a tip angle of 30-45°, a thickness of 2-3mm, and a length of 150-200mm, first, vertically insert the wedge tool along the foam gap between the battery cell and the end plate, with an insertion depth of ≤3cm, to separate the top foam from the end plate; after separation, use diagonal pliers to tear out the end plate. If the end plate breaks in the middle, use an iron hook with a diameter of 3-4mm, a tip ground into an arc with a radius of ≥2mm, to insert into the gap and hook out the bottom end plate. The iron hook should move freely at the bottom of the gap before proceeding; then, place the wedge tool vertically between the two battery cells. Place the wedge-shaped tool vertically downwards with a rubber hammer weighing 0.2-0.3 kg, allowing the tool to slowly and vertically enter between the two battery cells. Once a gap of ≥5 mm appears between the cells, pry the wedge tool back and forth at an amplitude of 5-10 mm and a frequency of 10-15 times / min to widen the separation gap between the adhesive layer and the battery cell and allow the wetting liquid to further penetrate into the unsoftened adhesive layer. Then, use a silicone-coated non-metallic battery cell clamp to pull out the battery cell with a pulling force of 50-80 N and a uniform speed of ≤5 cm / s, avoiding excessive force that could cause the battery cell to dent. Repeat the above operation to separate and remove the individual battery cells one by one.

[0036] Step Six: Cleaning and Post-processing of Battery Cells; Using a PTFE plastic spatula with a blade thickness of 1-2mm, keep the spatula surface parallel to the bottom of the box and use a pushing force of ≤5N to remove residual adhesive inside the battery pack box. After vacuuming the surface particles of the box with an industrial vacuum cleaner, wipe the surface of the box with a microfiber lint-free cloth with a concentration of ≥99.7% anhydrous ethanol using a microfiber lint-free cloth with a weight of 200-300g / ㎡. After cleaning, let the box stand in an environment with a temperature of 25±2℃ and a humidity of 60% for 1 hour. After standing, inspect the appearance of the box, requiring no residual adhesive and no scratches. For the separated individual battery cells, first remove the blue film from the cell, then wipe the surface of the cell with a microfiber lint-free cloth with a concentration of ≥99.5% isopropyl alcohol to remove adhesive stains and dirt. Let it air dry for 10 minutes. The battery cells undergo visual and performance testing. Visual testing includes checking that the aluminum casing has no dents / scratches with a depth ≥0.5mm and a length ≥5mm, no deformation, that the explosion-proof valve is intact and undamaged, and that the cell's QR code is clear, identifiable, and conforms to VPS standards. Performance testing includes checking that the cell's capacity retention rate is ≥80%, internal resistance ≤100mΩ, and capacity retention rate is ≥70% after 500 charge-discharge cycles. Based on the test results, the cells are classified. Cells meeting the above visual and performance standards are considered qualified and are re-coated with blue film for reuse. The remaining cells are recycled. When storing the cells, ensure that the positive and negative terminals are isolated to prevent short circuits. The storage environment should be at a temperature of 40℃ and a humidity ≤75%. This invention fundamentally solves the industry pain points of traditional CTP battery packs, namely, the difficulty of manual disassembly and removal of adhesives, the risk of cell damage, the high safety risks, and the low product recycling rate. Through a targeted ester-ketone composite solvent system design combined with the addition of environmentally friendly anti-volatile additives, and refined operations such as negative pressure permeation and sealing replenishment, it achieves efficient and gentle swelling and softening of polyol-isocyanate structural adhesives. The entire disassembly process is free of violent handling, maximizing the integrity of the cells and the casing, significantly improving the recycling rate of qualified cells, and fully realizing the cascade utilization value of the disassembled cells. Simultaneously, standardized and precise operating parameters and specifications have been established for the entire process, from safe pre-treatment discharge and shielding to busbar switching. From cutting and cleaning the casing to separating individual cells and classifying them for testing, each step avoids safety risks and material damage issues such as sparking, cell denting, and marking corrosion. This makes the disassembly operation safe, controllable, and easy to learn, effectively reducing the labor intensity of operators. In addition, the composite solvent used for disassembly can be reused after filtration and purification. The cleaning reagents are environmentally friendly, low in toxicity, and leave no residue, which reduces the cost of consumables for disassembly and improves resource utilization. Moreover, the entire process does not require large-scale specialized disassembly equipment, has a simple process flow, and is adaptable to the disassembly needs of different specifications of CTP battery packs. It is easy to achieve industrial-scale promotion and combines safety, non-destructiveness, economy, and environmental protection, greatly enhancing the industrialization value of CTP battery pack recycling and disassembly.

[0037] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A solvent-based disassembly method for disassembling a CTP battery pack without damage, characterized in that, Follow these steps: Step 1, Safety Pre-processing; Discharge the CTP battery pack until the cell voltage is within a safe range, then remove it after letting it stand for a period of time. Step 2: Cut the module busbar; Step 3: Clean the box; Step 4: Solvent impregnation of the battery pack; Add 0.5%-2% by mass of an environmentally friendly anti-volatile additive to the solvent, then pour it into the module and keep it in contact with the module structural adhesive for a sufficient time to soften or lose its adhesiveness. Step 5: Separate individual battery cells; Step Six: Cleaning and Post-processing of Battery Cells; Remove the blue film from the individual battery cells and clean the separated individual battery cells.

2. The solvent-based disassembly method of claim 1, wherein, In step one, the settling time is 15-30 minutes. When disassembling, the low-voltage wiring harness must be disconnected first, and then the high-voltage circuit must be disconnected. The CTP battery pack is then checked for sealing by visual inspection combined with holding the pressure at 0.05-0.1MPa for 5 minutes without pressure drop, to ensure that there are no leaks and that it can accommodate solvents.

3. The solvent-based disassembly method of claim 1, wherein, In step two, after disassembly, the busbars inside the CTP battery pack are exposed. The busbars are then separated using an aluminum cutting machine. When making double-slit cuts on the busbars, the cutting depth should not exceed 2mm. Subsequently, diagonal pliers are used to tear them apart. During the cutting and use of diagonal pliers, attention should be paid to the spacing between adjacent cells to avoid simultaneous contact that could cause arcing.

4. The solvent-based disassembly method of claim 1, wherein, In step three, an industrial vacuum cleaner with a negative pressure value of ≥0.08MPa is used to remove aluminum shavings generated during the manifold cutting. Aluminum shavings that are difficult to remove from the CTP battery pack housing and module gaps are removed using adhesive bags and insulating rods.

5. The solvent-based disassembly method of claim 1, wherein, In step four, the solvent is selected as an ester-ketone composite organic solvent for polyol-isocyanate type structural adhesives, and the composite organic solvent is a mixture of ethyl acetate and acetone in a volume ratio of 4:

6. The anti-volatile additive is one of tributyl citrate and dodecyl alcohol ester or a mixture of both in a mass ratio of 1:

1. The mixture is stirred evenly to obtain the impregnation solution.

6. The solvent-based disassembly method of claim 5, wherein, In step four, the operator wears rubber gloves and uses a beaker to pour the impregnation liquid into the gaps at the edge of the enclosure until the liquid level near the end of the module exceeds the structural adhesive by 2-3 cm. The module gaps in the middle of the enclosure beams are injected with the impregnation liquid until the liquid level is level with the beams. During injection, a negative pressure of 0.03-0.05 MPa is applied inside the battery pack for osmosis treatment, and the ambient temperature is maintained at 25±1℃. Subsequent replenishment is performed every 5 hours. The upper surface of the battery pack is then sealed with a stretch film to prevent solvent evaporation, allowing the impregnation liquid to fully contact and impregnate the structural adhesive for 24-48 hours, softening or causing the adhesive to lose its bonding strength. After impregnation, the remaining impregnation liquid is collected and pre-treated by coarse filtration through a 100-200 mesh filter and fine filtration through a 0.22μm precision filter membrane.

7. The non-destructive disassembly method for CTP battery packs based on solvent disassembly according to claim 6, characterized in that, The mixing and stirring of the impregnation solution is carried out by magnetic stirring at a speed of 200-300 r / min for 5-10 min to ensure that the anti-volatile additive and the composite organic solvent are fully mixed. The injection device is a syringe pump with an injection flow rate of 5-10 mL / min to avoid splashing of the impregnation solution and contaminating the battery cell.

8. The non-destructive disassembly method for CTP battery packs based on solvent disassembly according to claim 1, characterized in that, In step five, the wedge-shaped tool is placed vertically between the two battery cells, and the rubber hammer is used to slowly and vertically insert the wedge-shaped tool between the two battery cells. After a gap appears between the battery cells, the battery cells are clamped out. Then the above operation is repeated to separate the remaining battery cells.

9. The non-destructive disassembly method for CTP battery packs based on solvent disassembly according to claim 1, characterized in that, In step six, a plastic spatula is used to remove residual adhesive from the battery pack box parallel to the surface of the box. After removing particles from the surface of the box with an industrial vacuum cleaner, the residual adhesive on the surface of the box is wiped with a lint-free cloth dipped in anhydrous ethanol. After cleaning, the box is left to stand at room temperature and pressure for 1 hour. For the separated individual battery cells, the blue film on the battery cell is first removed, and then the adhesive residue and stains on the surface of the battery cell are wiped with a lint-free cloth dipped in isopropyl alcohol. Subsequently, the battery cells are subjected to appearance inspection and performance testing.

10. A non-destructive disassembly method for CTP battery packs based on solvent disassembly according to claim 9, characterized in that, The appearance inspection includes checking whether there are dents, scratches, or deformations in the aluminum shell of the battery cell, whether the explosion-proof valve is intact and undamaged, and whether the QR code of the battery cell is clear and identifiable; the performance inspection includes capacity retention rate, internal resistance, and cycle life testing; the battery cells are classified according to the test results. Battery cells with a capacity retention rate ≥80% and internal resistance ≤100mΩ are qualified battery cells and are re-coated with blue film for secondary use. The remaining battery cells are recycled and regenerated. During the storage of the battery cells, the positive and negative electrodes are kept isolated from each other to avoid short circuits.

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