Method for stripping positive electrode material of retired power battery based on eutectic solvent

Abstract

This invention discloses a method for stripping retired power battery cathode materials using a eutectic solvent. Step one: Prepare a eutectic solvent separator by thoroughly mixing the hydrogen bond donor, hydrogen bond acceptor, and additives in the eutectic solvent formulation, followed by heating to obtain the eutectic solvent separator. Step two: Immerse the retired power battery cathode material thoroughly in the eutectic solvent separator obtained in step one, and heat and stir until the cathode material is completely stripped from the current collector. Step three: Wash and dry the cathode material and current collector obtained in step two with distilled water and ethanol, respectively, to obtain cathode material and current collector suitable for regeneration. This method has a simple operation process, the separator can be reused at low cost, and the separation process is safe, environmentally friendly, and energy-efficient, making it a highly promising novel stripping method.

Description

Technical Field

[0001] This invention belongs to the field of waste power battery resource recycling technology, specifically involving a method for stripping off the cathode material of retired power batteries based on a eutectic solvent. Background Technology

[0002] With the continued growth of the global economy and the support of national strategies, the number of new energy vehicles has increased at an even faster pace in recent years. Lithium batteries, as a crucial component of new energy vehicles, have also experienced explosive growth. However, the lifespan of lithium batteries is approximately 5-8 years. Because lithium batteries contain important strategic metals such as lithium, nickel, cobalt, and manganese, as well as other toxic substances, they contain organic or inorganic components that pose serious environmental hazards. Improper handling will not only lead to resource waste but also cause severe environmental pollution.

[0003] The harsh high-temperature, high-pressure, or highly corrosive conditions in existing mainstream processes can easily trigger side reactions between electrode materials and current collectors, leading to material contamination. For example, while high-temperature pyrolysis can decompose binders to separate electrode materials and current collectors, its high-temperature process (typically >500℃) promotes the diffusion of current collector atoms (such as Al3+) into the electrode material lattice, causing component contamination. In direct regeneration processes, such lattice doping will cause crystal distortion and blockage of lithium-ion migration channels, significantly reducing the specific capacity and cycle stability of the recycled material. In metallurgical recycling processes, contaminated electrode materials require deep chemical purification to recover valuable metal products, significantly increasing recycling costs and environmental pollution risks. Therefore, there is an urgent need to develop an electrode material separation technology with relatively mild process conditions to achieve efficient separation of high-purity electrode materials and current collectors while suppressing atomic interdiffusion, thereby improving the quality of recycled products and reducing the cost of subsequent recycling processes. Summary of the Invention

[0004] The purpose of this invention is to provide a method for stripping retired power battery cathode materials based on a eutectic solvent, addressing the shortcomings of the existing technology.

[0005] The technical solution of this invention: A method for stripping retired power battery cathode materials using a eutectic solvent, comprising the following steps:

[0006] Step 1: Prepare a eutectic solvent separator by thoroughly mixing the hydrogen bond donor, hydrogen bond acceptor, and auxiliary agent in the eutectic solvent formulation, and then heating to obtain the eutectic solvent separator;

[0007] Step 2: Immerse the positive electrode of the retired power battery thoroughly in the eutectic separator obtained in Step 1, and heat and stir until the positive electrode material is completely detached from the current collector;

[0008] Step 3: After washing and drying the positive electrode material and current collector obtained in Step 2 with distilled water and ethanol respectively, a positive electrode material and current collector that can be recycled are obtained.

[0009] In the aforementioned method for stripping retired power battery cathode materials using a eutectic solvent, in step one, the hydrogen bond donor is selected from one or more of ethylene glycol, glycerol, propylene glycol, isopropanol, butanediol, and polyethylene glycol.

[0010] In the aforementioned method for stripping retired power battery cathode materials using a eutectic solvent, in step one, the hydrogen bond acceptor is selected from one or more of the following: dipotassium hydrogen phosphate, potassium dihydrogen phosphate, potassium phosphate, potassium carbonate, potassium bicarbonate, disodium hydrogen phosphate, sodium dihydrogen phosphate, sodium phosphate, sodium carbonate, sodium bicarbonate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium phosphate, ammonium bicarbonate, potassium acetate, sodium acetate, potassium citrate, and betaine.

[0011] In the aforementioned method for stripping retired power battery cathode materials using a eutectic solvent, in step one, the additive is selected from one or more of water, ethanol, tert-butanol, N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylformamide, polyethylene glycol, and ethylene glycol monoethyl ether.

[0012] In the aforementioned method for stripping retired power battery cathode materials based on eutectic solvent, in step one, the molar ratio of hydrogen bond donor, hydrogen bond acceptor and auxiliary agent of the eutectic solvent separator is 1:10:0.5~3:10:1, the synthesis temperature is 60~100 ℃, the stirring speed is 400~600 rpm, and the heating and mixing time is 20~60 min.

[0013] In the aforementioned method for stripping retired power battery cathode materials using a eutectic solvent, in step two, the stripping time is 8-20 min and the temperature is 80-120 ℃.

[0014] The beneficial effects of this invention are as follows: The eutectic solvent prepared by this invention will not react with the cathode material and the current collector, but will specifically bind to the H atoms inside the PVDF, resulting in the formation of C=C, thereby causing the degradation of PVDF from macromolecules to small molecules, losing its bonding effect, and realizing the separation of the cathode material from the aluminum foil.

[0015] Compared with existing inventions, the present invention has the following advantages:

[0016] (1) The present invention uses a low eutectic solvent separator to separate the cathode material of retired lithium battery. This method has high separation efficiency and low loss of electrode material and current collector, which is beneficial to the direct regeneration and application of cathode material in the future.

[0017] (2) This invention utilizes the negative charge of carbonic acid and phosphate to remove H atoms from the CH bond, causing an elimination reaction that promotes the formation of C=C, thereby initiating a chain reaction that degrades PVDF into small molecules and deactivates it, thus achieving stripping. This method breaks through the dissolution mechanism relied upon by traditional DES stripping agents and is original.

[0018] (3) The low eutectic solvent separating agent used in this invention has low raw material cost, simple preparation process, no pollutant generation, and can be recycled, thus having good cost-effectiveness.

[0019] (4) Under the condition of ensuring good separation efficiency, the temperature and time used for separation are much lower than those of traditional separation methods, which greatly reduces the separation energy consumption. Attached Figure Description

[0020] Figure 1 The experimental example shows the main element content of the positive electrode of a retired power battery before separation and the positive electrode material and aluminum foil after separation.

[0021] Figure 2 This experiment demonstrates the relationship between the separation performance of eutectic solvents and the number of cycles.

[0022] Figure 3 The separation efficiency of the positive electrode material of the retired power battery in the experimental example. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention.

[0024] Embodiment 1 of the present invention: A method for stripping retired power battery cathode materials based on a eutectic solvent, comprising the following steps:

[0025] Step 1: Prepare a eutectic solvent separator by thoroughly mixing ethylene glycol, dipotassium hydrogen phosphate, and tert-butanol in a molar ratio of 1:10:0.5. Stir the mixture magnetically at 80°C for 40 minutes at a stirring speed of 500 rpm to obtain the eutectic solvent separator.

[0026] Step 2: Immerse the positive electrode of the retired power battery in the eutectic separator obtained in Step 1, and stir magnetically at 100°C for 12 minutes until the positive electrode material is completely detached from the current collector.

[0027] Step 3: After washing and drying the positive electrode material and current collector obtained in Step 2 with distilled water and ethanol respectively, a positive electrode material and current collector that can be recycled are obtained.

[0028] Embodiment 2 of the present invention: A method for stripping retired power battery cathode materials based on a eutectic solvent, comprising the following steps:

[0029] Step 1: Prepare a eutectic solvent separator by thoroughly mixing glycerol, potassium phosphate, and ethanol in a molar ratio of 2:10:1 and magnetically stirring at 100°C for 30 minutes at a stirring speed of 450 rpm to obtain the eutectic solvent separator.

[0030] Step 2: Immerse the positive electrode of the retired power battery in the eutectic separator obtained in Step 1, and stir magnetically at 110°C for 10 minutes until the positive electrode material is completely detached from the current collector.

[0031] Step 3: After washing and drying the positive electrode material and current collector obtained in Step 2 with distilled water and ethanol respectively, a positive electrode material and current collector that can be recycled are obtained.

[0032] Embodiment 3 of the present invention: A method for stripping retired power battery cathode materials based on a eutectic solvent, comprising the following steps:

[0033] Step 1: Prepare a eutectic solvent separator by thoroughly mixing propylene glycol, potassium carbonate, and N-methylpyrrolidone in a molar ratio of 3:10:0.5. Stir the mixture magnetically at 70°C for 50 minutes at a stirring speed of 500 rpm to obtain the eutectic solvent separator.

[0034] Step 2: Immerse the positive electrode of the retired power battery thoroughly in the eutectic separator obtained in Step 1, and stir magnetically at 80°C for 20 minutes until the positive electrode material is completely peeled off from the current collector.

[0035] Step 3: After washing and drying the positive electrode material and current collector obtained in Step 2 with distilled water and ethanol respectively, a positive electrode material and current collector that can be recycled are obtained.

[0036] Example 4 of the present invention: A method for stripping retired power battery cathode materials based on a eutectic solvent, comprising the following steps:

[0037] Step 1: Prepare a eutectic solvent separator by thoroughly mixing isopropanol, potassium hydrogen phosphate, and dimethyl sulfoxide in a molar ratio of 3:10:1. Stir the mixture magnetically at 60°C for 60 minutes at a stirring speed of 600 rpm to obtain the eutectic solvent separator.

[0038] Step 2: Immerse the positive electrode of the retired power battery thoroughly in the eutectic separator obtained in Step 1, and stir magnetically at 120°C for 8 minutes until the positive electrode material is completely detached from the current collector.

[0039] Step 3: After washing and drying the positive electrode material and current collector obtained in Step 2 with distilled water and ethanol respectively, a positive electrode material and current collector that can be recycled are obtained.

[0040] Embodiment 5 of the present invention: A method for stripping retired power battery cathode materials based on a eutectic solvent, comprising the following steps:

[0041] Step 1: Prepare a eutectic solvent separator by thoroughly mixing butanediol, disodium hydrogen phosphate, and N,N-dimethylformamide in a molar ratio of 1:10:1. Stir the mixture magnetically at 80°C for 40 min at a stirring speed of 500 rpm to obtain the eutectic solvent separator.

[0042] Step 2: Immerse the positive electrode of the retired power battery thoroughly in the eutectic separator obtained in Step 1, and stir magnetically at 100°C for 15 minutes until the positive electrode material is completely detached from the current collector.

[0043] Step 3: After washing and drying the positive electrode material and current collector obtained in Step 2 with distilled water and ethanol respectively, a positive electrode material and current collector that can be recycled are obtained.

[0044] Embodiment 6 of the present invention: A method for stripping retired power battery cathode materials based on a eutectic solvent, comprising the following steps:

[0045] Step 1: Prepare a eutectic solvent separator. Select polyethylene glycol, sodium dihydrogen phosphate, and polyethylene glycol and mix them thoroughly. The molar ratio of polyethylene glycol, sodium dihydrogen phosphate, and polyethylene glycol is 2:10:1. Stir magnetically at 80°C for 40 min at a stirring speed of 500 rpm to obtain the eutectic solvent separator.

[0046] Step 2: Immerse the positive electrode of the retired power battery in the eutectic separator obtained in Step 1, and stir magnetically at 100°C for 12 minutes until the positive electrode material is completely detached from the current collector.

[0047] Step 3: After washing and drying the positive electrode material and current collector obtained in Step 2 with distilled water and ethanol respectively, a positive electrode material and current collector that can be recycled are obtained.

[0048] Embodiment 7 of the present invention: A method for stripping retired power battery cathode materials based on a eutectic solvent, comprising the following steps:

[0049] Step 1: Prepare a eutectic solvent separator by thoroughly mixing ethylene glycol, betaine, and water in a molar ratio of 1:10:1 and magnetically stirring at 80°C for 40 minutes at a stirring speed of 500 rpm to obtain the eutectic solvent separator.

[0050] Step 2: Immerse the positive electrode of the retired power battery in the eutectic separator obtained in Step 1, and stir magnetically at 100°C for 12 minutes until the positive electrode material is completely detached from the current collector.

[0051] Step 3: After washing and drying the positive electrode material and current collector obtained in Step 2 with distilled water and ethanol respectively, a positive electrode material and current collector that can be recycled are obtained.

[0052] Example 8 of the present invention: A method for stripping retired power battery cathode materials based on a eutectic solvent, comprising the following steps:

[0053] Step 1: Prepare a eutectic solvent separator by thoroughly mixing polyethylene glycol, ammonium dihydrogen phosphate, and dimethyl sulfoxide in a molar ratio of 2:10:0.8. Stir the mixture magnetically at 80°C for 40 minutes at a stirring speed of 500 rpm to obtain the eutectic solvent separator.

[0054] Step 2: Immerse the positive electrode of the retired power battery in the eutectic separator obtained in Step 1, and stir magnetically at 100°C for 12 minutes until the positive electrode material is completely detached from the current collector.

[0055] Step 3: After washing and drying the positive electrode material and current collector obtained in Step 2 with distilled water and ethanol respectively, a positive electrode material and current collector that can be recycled are obtained.

[0056] To verify the effectiveness of the method of the present invention, the following experiment was conducted:

[0057] (1) Weigh out dipotassium hydrogen phosphate (17.418g), ethylene glycol (62.07g) and water (9g) respectively, add them to a 100ml round-bottom flask, mix them evenly, and stir magnetically at 60℃ for 30min. The solid completely dissolves to form a colorless and transparent solution, and a eutectic solvent separating agent is obtained.

[0058] (2) Immerse the positive electrode sheet in the obtained eutectic solution separating agent without contacting the stir bar, and stir magnetically at 100°C for 8 minutes until the positive electrode material is fully separated from the aluminum foil;

[0059] (3) The positive electrode material and aluminum foil are separated by centrifugation. After washing the positive electrode material and aluminum foil with distilled water, they are placed in a vacuum drying oven for drying. The collected material after drying can be used for recycling.

[0060] (4) Repeat steps (2) and (3) until the eutectic solvent separator is deactivated.

[0061] Table 1. Main elemental contents of lithium iron phosphate cathode materials before and after stripping

[0062] Before stripping the positive electrode 8.7946 2.3112 20.5541 After stripping the cathode material 0.1603 2.5009 24.8008 Aluminum foil 84.1033 0.004 0.3506

Claims

1. A method for stripping retired power battery cathode materials using a eutectic solvent, characterized in that: Includes the following steps: Step 1: Prepare a eutectic solvent separator by thoroughly mixing the hydrogen bond donor, hydrogen bond acceptor, and auxiliary agent in the eutectic solvent formulation, and then heating to obtain the eutectic solvent separator; Step 2: Immerse the positive electrode of the retired power battery thoroughly in the eutectic separator obtained in Step 1, and heat and stir until the positive electrode material is completely detached from the current collector; Step 3: After washing and drying the positive electrode material and current collector obtained in Step 2 with distilled water and ethanol respectively, a positive electrode material and current collector that can be recycled are obtained.

2. The method for stripping retired power battery cathode materials using a eutectic solvent according to claim 1, characterized in that: In step one, the hydrogen bond donor is selected from one or more of ethylene glycol, glycerol, propylene glycol, isopropanol, butanediol, and polyethylene glycol.

3. The method for stripping retired power battery cathode materials based on a eutectic solvent according to claim 1, characterized in that: In step one, the hydrogen bond acceptor is selected from one or more of the following: dipotassium hydrogen phosphate, potassium dihydrogen phosphate, potassium phosphate, potassium carbonate, potassium bicarbonate, disodium hydrogen phosphate, sodium dihydrogen phosphate, sodium phosphate, sodium carbonate, sodium bicarbonate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium phosphate, ammonium bicarbonate, potassium acetate, sodium acetate, potassium citrate, and betaine.

4. The method for stripping retired power battery cathode materials based on a eutectic solvent according to claim 1, characterized in that: In step one, the additive is selected from one or more of water, ethanol, tert-butanol, N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylformamide, polyethylene glycol, and ethylene glycol monoethyl ether.

5. The method for stripping retired power battery cathode materials based on a eutectic solvent according to claim 1, characterized in that: In step one, the molar ratio of hydrogen bond donor, hydrogen bond acceptor and auxiliary agent of the eutectic solvent separator is 1:10:0.5~3:10:1, the synthesis temperature is 60~100 ℃, the stirring speed is 400~600 rpm, and the heating and mixing time is 20~60 min.

6. The method for stripping retired power battery cathode materials based on a eutectic solvent according to claim 1, characterized in that: In step two, the peeling time is 8~20 min and the temperature is 80~120 ℃.

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