Methods for dismantling waste lithium batteries and the dismantling fluids used

Abstract

This invention discloses a dismantling solution, which, by weight, comprises 100 parts, the following main components: 20-40 parts complexing agent, 5-15 parts surface coating agent, 15 parts co-solvent, and the remainder being deionized water. By employing a ternary compound system of "complexing agent + surface coating agent + co-solvent," the complexing agent directionally binds to the electrolyte, effectively preventing electrolyte hydrolysis and corrosion. The surface coating agent forms a protective layer, preventing the electrode from reacting and forming a passivation film, thus ensuring the electrochemical activity of the active material. Furthermore, the dismantling method utilizes an integrated process of immersion removal of the protective layer, dismantling solution regeneration, and material recovery. This process is compact, requires no additional acid washing, calcination, or wastewater treatment units, simplifies the process, and does not generate harmful gases, making it more environmentally friendly.

Description

Technical Field

[0001] This invention relates to lithium battery technology, and in particular to a method for dismantling waste lithium batteries and the dismantling fluid used therein. Background Technology

[0002] With the widespread application of lithium-ion batteries in new energy vehicles, energy storage equipment, and other fields, the amount of waste lithium-ion batteries generated has increased significantly. Their recycling has become crucial for ensuring sustainable industrial development and reducing resource waste and environmental pollution. Waste lithium-ion batteries require discharge treatment before dismantling, but residual electrolyte, consisting of lithium hexafluorophosphate as the electrolyte salt and carbonate compounds as the organic solvent, remains inside the batteries. This residual electrolyte is the core source of potential hazards during the dismantling process.

[0003] Existing technologies for dismantling spent lithium-ion batteries generally suffer from the following shortcomings: First, in traditional water-washing dismantling processes, residual lithium hexafluorophosphate readily undergoes violent hydrolysis with the aquatic environment, releasing highly corrosive hydrogen fluoride gas. This not only corrodes and damages the dismantling equipment but also reacts chemically with the surfaces of the positive and negative electrode active materials, generating inert substances such as lithium fluoride and lithium carbonate, forming a passivation film. This significantly weakens the electrochemical activity of the active materials, thereby increasing the cost of subsequent purification. Second, while supercritical fluid extraction technology can recover electrolytes, it requires operation under harsh conditions of high pressure and high temperature, resulting in high equipment investment costs and making it difficult to meet the needs of large-scale industrial production. Third, conventional extraction technologies only focus on the separation and removal of electrolytes or binders, neglecting the protection requirements of active materials. This leads to severe deterioration of the recovered active materials, making them unsuitable for direct regeneration. Fourth, some dismantling technologies use high-temperature roasting to remove impurities, which generates fluorine-containing waste gas, causing secondary pollution problems and contradicting the industrial concept of green recycling.

[0004] Therefore, developing a dismantling technology that can simultaneously achieve "surface protection of active materials and directional removal of electrolyte," and that is gentle, environmentally friendly, efficient, and suitable for industrial applications, has become an urgent technical problem to be solved in the field of waste lithium-ion battery recycling. Summary of the Invention

[0005] In view of this, the present invention addresses the deficiencies of the existing technology, and its main objective is to provide a method for dismantling waste lithium batteries and a dismantling fluid used therein. This method can effectively solve the problems of existing waste lithium battery dismantling methods releasing highly corrosive hydrogen fluoride gas, generating inert substances such as lithium fluoride and lithium carbonate and forming a passivation film, which significantly weakens the electrochemical activity of active materials and also generates fluorine-containing waste gas.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A disassembly solution, in 100 parts by weight, comprises the following main components: 20-40 parts of complexing agent, 5-15 parts of surface coating agent, 15 parts of cosolvent, and the remainder being deionized water.

[0007] As a preferred embodiment, the complexing agent is a crown ether.

[0008] As a preferred embodiment, the surface coating agent is composed of aluminum nitrate and aminoacetic acid.

[0009] As a preferred embodiment, the weight ratio of aluminum nitrate to aminoacetic acid is 4:1.

[0010] As a preferred embodiment, the co-solvent is polyethylene glycol.

[0011] A method for dismantling used lithium batteries includes the following steps: (1) The waste ternary lithium battery was completely discharged by salt water immersion method, and the casing, tabs and separator were removed to obtain the electrode assembly; (2) Immerse the electrode assembly obtained in step (1) into the disassembly solution and stir it. The stirring temperature is 30°C, the stirring rate is 150 r / min, and the stirring time is 2 h. Filter and separate to obtain the treated electrode assembly and the disassembly solution containing the complex. (3) The disintegration solution containing the complex obtained in step (2) was subjected to vacuum distillation at a distillation temperature of 80°C and a distillation pressure of 0.05 MPa to separate the LiPF6 complex and the regenerated disintegration solution. (4) The processed electrode assembly obtained in step (2) is dried at a temperature of 60°C for 3 hours. After vibration sorting, positive electrode active material, negative electrode active material and copper-aluminum current collector are obtained.

[0012] Compared with the prior art, the present invention has obvious advantages and beneficial effects. Specifically, as can be seen from the above technical solution: By adopting a ternary compound system of "complexing agent + surface coating agent + cosolvent", the complexing agent binds to the electrolyte in a targeted manner, effectively preventing electrolyte hydrolysis corrosion. The surface coating agent generates a protective layer to prevent the electrode from reacting and forming a passivation film, ensuring the electrochemical activity of the active material. Combined with the disassembly method, which adopts an integrated process of immersion to remove the protective layer, disassembly liquid regeneration, and material recovery, the steps are compact, requiring no additional acid washing, calcination, or wastewater treatment units. The process is simpler and does not produce harmful gases, making the process more environmentally friendly.

[0013] To more clearly illustrate the structural features and effects of the present invention, the present invention will be described in detail below with reference to several specific embodiments. Detailed Implementation

[0014] This invention discloses a dismantling solution, comprising, by weight, 100 parts, the following main components: 20-40 parts of a complexing agent, 5-15 parts of a surface coating agent, 15 parts of a co-solvent, and the remainder being deionized water; the complexing agent is a crown ether, the surface coating agent is composed of aluminum nitrate and glycine, the weight ratio of aluminum nitrate to glycine is 4:1, and the co-solvent is polyethylene glycol; the dismantling solution is prepared as follows: Weigh the corresponding components according to the above proportions. First, place deionized water in a reaction vessel and slowly add polyethylene glycol while continuously stirring at 22°C and a stirring rate of 100 r / min. After the polyethylene glycol is added, continue stirring for 18 minutes until completely dissolved to obtain the basic mixture. Next, add crown ether in batches, preferably in 3 batches, with each batch having the same weight of crown ether and an interval of 12 minutes. After the crown ether is added, continue stirring for 25 minutes. Then, add aluminum nitrate and stir for 18 minutes until completely dissolved. Next, add glycine and adjust the stirring rate to 130 r / min, and continue stirring for 35 minutes until completely dissolved. Stop stirring. Then, let stand for 25 minutes to remove surface micro-bubbles. Confirm that the solution is uniform and transparent without precipitation to obtain the disintegration solution, which is then sealed and stored for later use.

[0015] A method for dismantling used lithium batteries includes the following steps: (1) The waste ternary lithium battery was completely discharged by salt water immersion method, and the casing, tabs and separator were removed to obtain the electrode assembly; (2) Immerse the electrode assembly obtained in step (1) into the disassembly solution and stir it. The stirring temperature is 30°C, the stirring rate is 150 r / min, and the stirring time is 2 h. Filter and separate to obtain the treated electrode assembly and the disassembly solution containing the complex. (3) The disintegration solution containing the complex obtained in step (2) was subjected to vacuum distillation at a distillation temperature of 80°C and a distillation pressure of 0.05 MPa to separate the LiPF6 complex and the regenerated disintegration solution. (4) The processed electrode assembly obtained in step (2) is dried at a temperature of 60°C for 3 hours. After vibration sorting, positive electrode active material, negative electrode active material and copper-aluminum current collector are obtained.

[0016] The following detailed description is provided in conjunction with several embodiments and comparative examples.

[0017] Example 1 The mixture comprises 30 parts of a complexing agent, 10 parts of a surface coating agent, 15 parts of a co-solvent, and the remainder being deionized water; the complexing agent is a crown ether, the surface coating agent is composed of aluminum nitrate and glycine, the weight ratio of aluminum nitrate to glycine is 4:1, and the co-solvent is polyethylene glycol; the preparation method is as follows: Weigh the corresponding components according to the above proportions. First, place deionized water in a reaction vessel and slowly add polyethylene glycol while continuously stirring at 22°C and a stirring rate of 100 r / min. After the polyethylene glycol is added, continue stirring for 18 minutes until completely dissolved to obtain a basic mixture. Next, add crown ether in batches, preferably in 3 batches, with each batch having the same weight and an interval of 12 minutes. After the crown ether is added, continue stirring for 25 minutes. Then, add aluminum nitrate and stir for 18 minutes until completely dissolved. Next, add glycine and adjust the stirring rate to 130 r / min, and continue stirring for 35 minutes until completely dissolved. Stop stirring. Then, let stand for 25 minutes to remove surface bubbles. Confirm that the solution is uniform, transparent, and free of precipitate to obtain the dismantling solution. Finally, dismantle the waste lithium batteries using the dismantling solution prepared above, following the above method for dismantling waste lithium batteries.

[0018] Example 2 The mixture comprises 20 parts of a complexing agent, 15 parts of a surface coating agent, 15 parts of a co-solvent, and the remainder being deionized water; the complexing agent is a crown ether, the surface coating agent is composed of aluminum nitrate and glycine, the weight ratio of aluminum nitrate to glycine is 4:1, and the co-solvent is polyethylene glycol; the preparation method is as follows: Weigh the corresponding components according to the above proportions. First, place deionized water in a reaction vessel and slowly add polyethylene glycol while continuously stirring at 22°C and a stirring rate of 100 r / min. After the polyethylene glycol is added, continue stirring for 18 minutes until completely dissolved to obtain a basic mixture. Next, add crown ether in batches, preferably in 3 batches, with each batch having the same weight and an interval of 12 minutes. After the crown ether is added, continue stirring for 25 minutes. Then, add aluminum nitrate and stir for 18 minutes until completely dissolved. Next, add glycine and adjust the stirring rate to 130 r / min, and continue stirring for 35 minutes until completely dissolved. Stop stirring. Then, let stand for 25 minutes to remove surface bubbles. Confirm that the solution is uniform, transparent, and free of precipitate to obtain the dismantling solution. Finally, dismantle the waste lithium batteries using the dismantling solution prepared above, following the above method for dismantling waste lithium batteries.

[0019] Example 3 The mixture comprises 35 parts of a complexing agent, 5 parts of a surface coating agent, 15 parts of a co-solvent, and the remainder being deionized water; the complexing agent is a crown ether, the surface coating agent is composed of aluminum nitrate and glycine, the weight ratio of aluminum nitrate to glycine is 4:1, and the co-solvent is polyethylene glycol; the preparation method is as follows: Weigh the corresponding components according to the above proportions. First, place deionized water in a reaction vessel and slowly add polyethylene glycol while continuously stirring at 22°C and a stirring rate of 100 r / min. After the polyethylene glycol is added, continue stirring for 18 minutes until completely dissolved to obtain a basic mixture. Next, add crown ether in batches, preferably in 3 batches, with each batch having the same weight and an interval of 12 minutes. After the crown ether is added, continue stirring for 25 minutes. Then, add aluminum nitrate and stir for 18 minutes until completely dissolved. Next, add glycine and adjust the stirring rate to 130 r / min, and continue stirring for 35 minutes until completely dissolved. Stop stirring. Then, let stand for 25 minutes to remove surface bubbles. Confirm that the solution is uniform, transparent, and free of precipitate to obtain the dismantling solution. Finally, dismantle the waste lithium batteries using the dismantling solution prepared above, following the above method for dismantling waste lithium batteries.

[0020] Example 4 The mixture comprises 40 parts of a complexing agent, 10 parts of a surface coating agent, 15 parts of a co-solvent, and the remainder being deionized water; the complexing agent is a crown ether, the surface coating agent is composed of aluminum nitrate and glycine, the weight ratio of aluminum nitrate to glycine is 4:1, and the co-solvent is polyethylene glycol; the preparation method is as follows: Weigh the corresponding components according to the above proportions. First, place deionized water in a reaction vessel and slowly add polyethylene glycol while continuously stirring at 22°C and a stirring rate of 100 r / min. After the polyethylene glycol is added, continue stirring for 18 minutes until completely dissolved to obtain a basic mixture. Next, add crown ether in batches, preferably in 3 batches, with each batch having the same weight and an interval of 12 minutes. After the crown ether is added, continue stirring for 25 minutes. Then, add aluminum nitrate and stir for 18 minutes until completely dissolved. Next, add glycine and adjust the stirring rate to 130 r / min, and continue stirring for 35 minutes until completely dissolved. Stop stirring. Then, let stand for 25 minutes to remove surface bubbles. Confirm that the solution is uniform, transparent, and free of precipitate to obtain the dismantling solution. Finally, dismantle the waste lithium batteries using the dismantling solution prepared above, following the above method for dismantling waste lithium batteries.

[0021] Example 5 The mixture comprises 40 parts of a complexing agent, 15 parts of a surface coating agent, 15 parts of a co-solvent, and the remainder being deionized water; the complexing agent is a crown ether, the surface coating agent is composed of aluminum nitrate and glycine, the weight ratio of aluminum nitrate to glycine is 4:1, and the co-solvent is polyethylene glycol; the preparation method is as follows: Weigh the corresponding components according to the above proportions. First, place deionized water in a reaction vessel and slowly add polyethylene glycol while continuously stirring at 22°C and a stirring rate of 100 r / min. After the polyethylene glycol is added, continue stirring for 18 minutes until completely dissolved to obtain a basic mixture. Next, add crown ether in batches, preferably in 3 batches, with each batch having the same weight and an interval of 12 minutes. After the crown ether is added, continue stirring for 25 minutes. Then, add aluminum nitrate and stir for 18 minutes until completely dissolved. Next, add glycine and adjust the stirring rate to 130 r / min, and continue stirring for 35 minutes until completely dissolved. Stop stirring. Then, let stand for 25 minutes to remove surface bubbles. Confirm that the solution is uniform, transparent, and free of precipitate to obtain the dismantling solution. Finally, dismantle the waste lithium batteries using the dismantling solution prepared above, following the above method for dismantling waste lithium batteries.

[0022] Example 6 The mixture comprises 36 parts of a complexing agent, 10 parts of a surface coating agent, 15 parts of a co-solvent, and the remainder being deionized water; the complexing agent is a crown ether, the surface coating agent is composed of aluminum nitrate and glycine, the weight ratio of aluminum nitrate to glycine is 4:1, and the co-solvent is polyethylene glycol; the preparation method is as follows: Weigh the corresponding components according to the above proportions. First, place deionized water in a reaction vessel and slowly add polyethylene glycol while continuously stirring at 22°C and a stirring rate of 100 r / min. After the polyethylene glycol is added, continue stirring for 18 minutes until completely dissolved to obtain a basic mixture. Next, add crown ether in batches, preferably in 3 batches, with each batch having the same weight and an interval of 12 minutes. After the crown ether is added, continue stirring for 25 minutes. Then, add aluminum nitrate and stir for 18 minutes until completely dissolved. Next, add glycine and adjust the stirring rate to 130 r / min, and continue stirring for 35 minutes until completely dissolved. Stop stirring. Then, let stand for 25 minutes to remove surface bubbles. Confirm that the solution is uniform, transparent, and free of precipitate to obtain the dismantling solution. Finally, dismantle the waste lithium batteries using the dismantling solution prepared above, following the above method for dismantling waste lithium batteries.

[0023] Comparative Example 1 The mixture comprises 15 parts of a complexing agent, 10 parts of a surface coating agent, 15 parts of a co-solvent, and the remainder being deionized water; the complexing agent is a crown ether, the surface coating agent is composed of aluminum nitrate and aminoacetic acid in a weight ratio of 4:1, and the co-solvent is polyethylene glycol; the preparation method is as follows: Weigh the corresponding components according to the above proportions. First, place deionized water in a reaction vessel and slowly add polyethylene glycol while continuously stirring at 22°C and a stirring rate of 100 r / min. After the polyethylene glycol is added, continue stirring for 18 minutes until completely dissolved to obtain a basic mixture. Next, add crown ether in batches, preferably in 3 batches, with each batch having the same weight and an interval of 12 minutes. After the crown ether is added, continue stirring for 25 minutes. Then, add aluminum nitrate and stir for 18 minutes until completely dissolved. Next, add glycine and adjust the stirring rate to 130 r / min, and continue stirring for 35 minutes until completely dissolved. Stop stirring. Then, let stand for 25 minutes to remove surface bubbles. Confirm that the solution is uniform, transparent, and free of precipitate to obtain the dismantling solution. Finally, dismantle the waste lithium batteries using the dismantling solution prepared above, following the above method for dismantling waste lithium batteries.

[0024] Comparative Example 2 The mixture comprises 30 parts of a complexing agent, 3 parts of a surface coating agent, 15 parts of a co-solvent, and the remainder being deionized water; the complexing agent is a crown ether, the surface coating agent is composed of aluminum nitrate and aminoacetic acid in a weight ratio of 2:1, and the co-solvent is polyethylene glycol; the preparation method is as follows: Weigh the corresponding components according to the above proportions. First, place deionized water in a reaction vessel and slowly add polyethylene glycol while continuously stirring at 22°C and a stirring rate of 100 r / min. After the polyethylene glycol is added, continue stirring for 18 minutes until completely dissolved to obtain a basic mixture. Next, add crown ether in batches, preferably in 3 batches, with each batch having the same weight and an interval of 12 minutes. After the crown ether is added, continue stirring for 25 minutes. Then, add aluminum nitrate and stir for 18 minutes until completely dissolved. Next, add glycine and adjust the stirring rate to 130 r / min, and continue stirring for 35 minutes until completely dissolved. Stop stirring. Then, let stand for 25 minutes to remove surface bubbles. Confirm that the solution is uniform, transparent, and free of precipitate to obtain the dismantling solution. Finally, dismantle the waste lithium batteries using the dismantling solution prepared above, following the above method for dismantling waste lithium batteries.

[0025] Comparative Example 3 First, the waste ternary lithium batteries are completely discharged using a brine immersion method. The outer casing, tabs, and separator are then removed to obtain the electrode assembly. Next, deionized water is placed in a reaction vessel, and the electrode assembly is immersed in the deionized water with continuous stirring at a temperature of 30°C, a stirring rate of 150 r / min, and a stirring time of 2 hours. After filtration, the treated electrode assembly is obtained. Then, the treated electrode assembly is dried at a temperature of 60°C for 3 hours. After vibration sorting, the positive electrode active material, negative electrode active material, and copper-aluminum current collector are obtained.

[0026] The performance of the above-mentioned embodiments and comparative examples was tested, and the test results are shown in Table 1.

[0027]

[0028] Table 1 Analysis of the above data shows that the disassembly solution prepared by the formulation of this invention has excellent removal effect and a high capacity retention rate of active materials, reaching up to 95.7%. The disassembly solution also has a high recovery rate, allowing for recycling and effectively reducing costs. Comparing Example 1 with Comparative Examples 1-3, the calculated regeneration cost is 238 yuan for Example 1, 612 yuan for Comparative Example 1, 545 yuan for Comparative Example 2, and 1030 yuan for Comparative Example 3. Example 1 has extremely low cost, making it highly suitable for widespread application. Furthermore, compared to Comparative Example 1, the complexing agent formulation in Comparative Example 1 is more efficient. The low concentration of LiF and Li2CO3 in the active material resulted in a low complexation removal rate, leaving a small amount of inert LiF on the surface of the active material and causing local damage to the protective layer. Compared with Comparative Example 2, Example 2 had a lower content of surface coating agent, which failed to form a dense protective film, resulting in a lower capacity retention rate of the active material. Furthermore, Comparative Example 3 used existing conventional technology, and the active material obtained contained a large amount of LiF and Li2CO3, forming a passivation film, which resulted in a very low lithium ion diffusion coefficient and performance far inferior to the active material obtained after dismantling waste lithium batteries using the dismantling solution of this invention. It is evident that this invention has made significant progress.

[0029] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A dismantling fluid, characterized in that: Based on 100 parts by weight, it includes the following main components: 20-40 parts complexing agent, 5-15 parts surface coating agent, 15 parts cosolvent, and the remainder is deionized water.

2. The disassembly fluid according to claim 1, characterized in that: The complexing agent is a crown ether.

3. The disassembly fluid according to claim 1, characterized in that: The surface coating agent is composed of aluminum nitrate and aminoacetic acid.

4. The disassembly fluid according to claim 3, characterized in that: The weight ratio of aluminum nitrate to aminoacetic acid is 4:

1.

5. The disassembly fluid according to claim 1, characterized in that: The co-solvent is polyethylene glycol.

6. A method for dismantling waste lithium batteries, characterized in that: It includes the following steps: (1) The waste ternary lithium battery was completely discharged by salt water immersion method, and the casing, tabs and separator were removed to obtain the electrode assembly; (2) Immerse the electrode assembly obtained in step (1) into the disassembly solution of any one of claims 1-5 and stir it. The stirring temperature is 30°C, the stirring rate is 150 r / min, the stirring time is 2 h, and the electrode assembly and disassembly solution containing complex are obtained by filtration and separation. (3) The disintegration solution containing the complex obtained in step (2) was subjected to vacuum distillation at a distillation temperature of 80°C and a distillation pressure of 0.05 MPa to separate the LiPF6 complex and the regenerated disintegration solution. (4) The processed electrode assembly obtained in step (2) is dried at a temperature of 60°C for 3 hours. After vibration sorting, positive electrode active material, negative electrode active material and copper-aluminum current collector are obtained.

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