Method for separating spent solid polymer lithium-ion battery electrode materials and separators

Abstract

The application is suitable for the technical field of battery recycling, and particularly relates to a method for separating electrode materials and separators of waste solid-state polymer lithium ion batteries, which comprises the following steps: discharging the waste solid-state polymer lithium ion batteries, disassembling the batteries to obtain aluminum foils and copper foils containing electrode materials and separators; performing water immersion treatment to obtain copper foils and separators containing electrode materials; performing dissolution treatment on the separators containing electrode materials by using N-methyl pyrrolidone to remove solid-state polymers, strip the electrode materials attached to the separators, and then obtain the electrode materials and the separators through twice filtration. The application realizes efficient separation of the electrode materials and the separators by using N-methyl pyrrolidone to dissolve the solid-state polymer electrolyte, and has the advantages of simple operation, high efficiency, good operability, no need for high-temperature energy consumption, and significant reduction of energy consumption and carbon emission, which is more green and environmentally friendly compared with the traditional high-temperature pyrolysis or calcination treatment method.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of battery recycling, and particularly relates to a method for separating electrode materials and separators of waste solid-state polymer lithium ion batteries. BACKGROUND

[0002] With the rapid development of new energy vehicles and portable electronic products, lithium ion batteries have become a key energy carrier. In particular, solid-state polymer lithium batteries, with their high energy density, excellent safety, and lightweight structure, have shown great prospects in high-end application fields. However, the performance of such batteries gradually deteriorates after long-term charge and discharge cycles, limiting their service life - electric vehicle batteries generally need to be replaced after 5 to 8 years, while the service life of batteries in mobile devices such as mobile phones and laptops is even shorter, usually 2 to 3 years. At present, a large number of retired lithium ion batteries have not entered the formal recycling channel, and the overall recycling rate is low. If these waste batteries are discarded or improperly disposed of, harmful substances in them may seep into the soil and water, posing a serious ecological and environmental risk and a potential threat to public health. On the other hand, waste batteries are rich in valuable metal materials such as copper, aluminum, lithium, and cobalt, and have high resource recycling potential. If not effectively recycled, it not only exacerbates resource consumption, but also violates the principle of sustainable development.

[0003] It is of practical significance to disassemble and process batteries that cannot be reused. The pretreatment process can achieve separation of different materials and components, and plays a prerequisite role in the entire recycling process. At present, the pretreatment of lithium battery recycling is mainly aimed at liquid electrolyte batteries, and there is a lack of pretreatment technology for polymer solid-state battery recycling. Unlike liquid electrolyte lithium ion batteries, high molecular polymers are added to polymer lithium batteries, making the entire pretreatment process more difficult, especially for electrode material stripping. Due to the presence of solid polymer electrolyte and battery aging, the electrode materials (positive and negative electrodes) and separators after disassembly are tightly combined, making it difficult to achieve efficient separation. SUMMARY

[0004] The purpose of the present application is to provide a method for separating electrode materials and separators of waste solid-state polymer lithium ion batteries, which aims to solve the problem of tight combination between electrode materials and separators after disassembly due to the presence of solid polymer electrolyte and battery aging, making it difficult to achieve efficient separation.

[0005] The present application is implemented as follows: a method for separating electrode materials and separators of waste solid-state polymer lithium ion batteries, the method comprising:

[0006] Discharge treatment is performed on the waste solid-state polymer lithium ion battery, and aluminum foil and copper foil containing electrode materials and separators are obtained by disassembling the waste solid-state polymer lithium ion battery;

[0007] subjecting the copper foil containing the electrode material and the separator to water immersion treatment to obtain the copper foil and the separator containing the electrode material;

[0008] subjecting the separator containing the electrode material to dissolution treatment by N-methyl pyrrolidone to remove the solid polymer and strip the electrode material attached to the separator, and then obtaining the electrode material and the separator by twice filtration;

[0009] In the step of subjecting the separator containing the electrode material to dissolution treatment by N-methyl pyrrolidone, the separator containing the electrode material is cut into pieces, the pieces of the separator are added to N-methyl pyrrolidone at a preset solid-liquid ratio, and stirring is performed to facilitate separation of the electrode material from the separator, and the preset solid-liquid ratio is 0.1-1 kg / L.

[0010] Preferably, the size of the pieces is 1-5 cm. 2 Preferably, the stirring speed is 10-60 revolutions per minute.

[0011] Preferably, in the step of subjecting the separator containing the electrode material to dissolution treatment by N-methyl pyrrolidone, the dissolved compound is polyethylene oxide, polysiloxane, polyacrylonitrile or polymethyl methacrylate.

[0012] Preferably, the waste solid polymer lithium ion battery is a ternary lithium battery, a lithium cobaltate lithium battery, a lithium manganate lithium battery or a Co-Al co-doped lithium nickel oxide lithium battery.

[0013] Preferably, in the step of discharging the waste solid polymer lithium ion battery, the waste solid polymer lithium ion battery is placed in brine for discharging, the discharging time is 12-24 hours, and the brine is a 5%-10% NaCl solution.

[0014] Preferably, after the discharging treatment, the waste solid polymer lithium ion battery is cleaned by ultrapure water and dried.

[0015] The method for separating the electrode material and the separator of the waste solid polymer lithium ion battery provided by the present application adopts N-methyl pyrrolidone (NMP) to dissolve the solid polymer electrolyte, which can realize efficient separation of the electrode material and the separator. The process is simple and efficient, has good operability, does not require high-temperature energy consumption compared with the traditional high-temperature pyrolysis or calcination treatment method, significantly reduces energy consumption and carbon emissions, and is more environmentally friendly. Due to its outstanding advantages in environmental friendliness and energy efficiency, the method has broad industrial application potential. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The flow framework diagram of the method for separating the electrode material and the separator of the waste solid polymer lithium ion battery provided by the embodiment of the present application is shown. DETAILED DESCRIPTION

[0017] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and should not be used to limit the present application.

[0018] As shown in FIG. 1, a flow chart of a method for separating electrode materials and separators of waste solid-state polymer lithium ion batteries provided by an embodiment of the present application is shown, and the method comprises the following steps: Figure 1

[0019] The waste solid-state polymer lithium ion batteries are discharged, and the aluminum foils and copper foils containing electrode materials and separators are obtained by disassembling the waste solid-state polymer lithium ion batteries;

[0020] The copper foils containing electrode materials and separators are subjected to water immersion treatment to obtain copper foils and separators containing electrode materials;

[0021] The separators containing electrode materials are subjected to dissolution treatment by N-methyl pyrrolidone to remove solid-state polymers, and the electrode materials attached to the separators are stripped off, and then the electrode materials and separators are obtained by twice filtration, and N-methyl pyrrolidone is recovered.

[0022] In the embodiment, the specific steps are as follows:

[0023] (1) The recovered waste solid-state polymer lithium ion batteries are discharged by salt water, and then washed by ultrapure water and dried, the salt water is a NaCl solution with a mass concentration of 5% to 10%, the discharge time is 12 to 24 hours, the drying temperature is 60°C, and the drying time is 12 to 24 hours;

[0024] (2) The batteries are disassembled by hand to obtain battery shells, aluminum foils and mixed electrode sheets;

[0025] (3) The mixed electrode sheets are washed several times by dimethyl carbonate, then soaked in ultrapure water to separate the separators containing electrode materials from the copper foils, and dried, the drying temperature is 60°C, and the drying time is 12 to 24 hours;

[0026] (4) The separators containing electrode materials are cut into small pieces and rapidly stirred in N-methyl pyrrolidone to separate the electrode materials from the separators, and then washed several times by ultrapure water and dried, the drying temperature is 60°C, the drying time is 12 to 24 hours, the solid-liquid ratio of the separator fragments to N-methyl pyrrolidone is 0.1 to 1 kg / L, and the reaction time is 10 to 60 minutes;

[0027] (5) The electrode materials are crushed, and the positive electrode materials and negative electrode materials are separated by air flotation.​

[0028] In order to illustrate the effect of the present application, the following comparative experiments are provided for illustration: Example 1

[0029] A method for separating electrode materials and separators of waste solid-state polymer lithium ion batteries, comprising the following steps:

[0030] 1. Discharge the recovered waste solid-state polymer lithium ion batteries with salt water, then wash with ultrapure water and dry;

[0031] 2. Manually disassemble the batteries to obtain battery shells, aluminum foils, and mixed electrode sheets;

[0032] 3. Wash the mixed electrode sheets with dimethyl carbonate several times, then immerse them in ultrapure water to separate the separators containing electrode materials from the copper foils, and dry them;

[0033] 4. Cut the separators containing electrode materials into small pieces, and quickly stir them in N-methyl pyrrolidone to separate the electrode materials from the separators, then wash them with ultrapure water several times and dry them; in this example, the material is 10g, and the N-methyl pyrrolidone is 100mL;

[0034] 5. Crush the electrode materials, then separate the positive electrode materials and negative electrode materials by air flotation.

[0035] Example 2

[0036] A method for separating electrode materials and separators of waste solid-state polymer lithium ion batteries, comprising the following steps:

[0037] 1. Discharge the recovered waste solid-state polymer lithium ion batteries with salt water, then wash with ultrapure water and dry;

[0038] 2. Manually disassemble the batteries to obtain battery shells, aluminum foils, and mixed electrode sheets;

[0039] 3. Wash the mixed electrode sheets with dimethyl carbonate several times, then immerse them in ultrapure water to separate the separators containing electrode materials from the copper foils, and dry them;

[0040] 4. Cut the separators containing electrode materials into small pieces, and quickly stir them in N-methyl pyrrolidone to separate the electrode materials from the separators, then wash them with ultrapure water several times and dry them; in this example, the material is 50g, and the N-methyl pyrrolidone is 100mL;

[0041] 5. Crush the electrode materials, then separate the positive electrode materials and negative electrode materials by air flotation.

[0042] Example 3

[0043] A method for separating electrode materials and separators of waste solid-state polymer lithium ion batteries, comprising the following steps:

[0044] 1. The recovered waste solid-state polymer lithium ion batteries are discharged in salt water, then washed with ultrapure water and dried;

[0045] 2. The batteries are manually disassembled to obtain battery shells, aluminum foils and mixed electrode sheets;

[0046] 3. The mixed electrode sheets are washed several times with dimethyl carbonate, then soaked in ultrapure water to separate the separators containing electrode materials from the copper foils, and dried;

[0047] 4. The separators containing electrode materials are cut into small pieces and rapidly stirred in N-methyl pyrrolidone to separate the electrode materials from the separators, then washed several times with ultrapure water and dried; In this example, the material is 100g and the N-methyl pyrrolidone is 100mL;

[0048] 5. The electrode materials are crushed, and the positive electrode materials and negative electrode materials are separated by air flotation.

[0049] Comparative Example 1

[0050] 1. The recovered waste solid-state polymer lithium ion batteries are discharged in salt water, then washed with ultrapure water and dried;

[0051] 2. The batteries are manually disassembled to obtain battery shells, aluminum foils and mixed electrode sheets;

[0052] 3. The mixed electrode sheets are washed several times with dimethyl carbonate, then soaked in ultrapure water to separate the separators containing electrode materials from the copper foils, and dried;

[0053] 4. The separators containing electrode materials are cut into small pieces and rapidly stirred in N-methyl pyrrolidone to separate the electrode materials from the separators, then washed several times with ultrapure water and dried; In this example, the material is 200g and the N-methyl pyrrolidone is 100mL.

[0054] Comparative Example 2

[0055] 1. The recovered waste solid-state polymer lithium ion batteries are discharged in salt water, then washed with ultrapure water and dried;

[0056] 2. The batteries are manually disassembled to obtain battery shells, aluminum foils and mixed electrode sheets;

[0057] 3. The mixed electrode sheets are washed several times with dimethyl carbonate, then soaked in ultrapure water to separate the separators containing electrode materials from the copper foils, and dried;

[0058] 4. The separator containing the electrode material is cut into small pieces and rapidly stirred in N-methyl pyrrolidone to separate the electrode material from the separator, and after washing several times with ultrapure water, drying is performed; the material in this comparative example is 300 g, and the N-methyl pyrrolidone is 100 mL.

[0059] Comparative Example 3

[0060] 1. The recovered waste solid-state polymer lithium ion battery is discharged with salt water, and then washed with ultrapure water and dried;

[0061] 2. The battery is manually disassembled to obtain the battery shell, aluminum foil, and mixed electrode sheet;

[0062] 3. The mixed electrode sheet is washed several times with dimethyl carbonate and then soaked in ultrapure water to separate the separator containing the electrode material from the copper foil, and drying is performed;

[0063] 4. The separator containing the electrode material is cut into small pieces and rapidly stirred in dichloromethane, and after washing several times with ultrapure water, drying is performed; the material in this comparative example is 10 g, and the dichloromethane is 100 mL.

[0064] Comparative Example 4

[0065] 1. The recovered waste solid-state polymer lithium ion battery is discharged with salt water, and then washed with ultrapure water and dried;

[0066] 2. The battery is manually disassembled to obtain the battery shell, aluminum foil, and mixed electrode sheet;

[0067] 3. The mixed electrode sheet is washed several times with dimethyl carbonate and then soaked in ultrapure water to separate the separator containing the electrode material from the copper foil, and drying is performed;

[0068] 4. The separator containing the electrode material is cut into small pieces and rapidly stirred in methanol, and after washing several times with ultrapure water, drying is performed; the material in this comparative example is 10 g, and the methanol is 100 mL.

[0069] Comparative Example 5

[0070] 1. The recovered waste solid-state polymer lithium ion battery is discharged with salt water, and then washed with ultrapure water and dried;

[0071] 2. The battery is manually disassembled to obtain the battery shell, aluminum foil, and mixed electrode sheet;

[0072] 3. The mixed electrode sheet is washed several times with dimethyl carbonate and then soaked in ultrapure water to separate the separator containing the electrode material from the copper foil, and drying is performed;

[0073] 4. The separator containing electrode material is cut into small pieces and stirred rapidly in acetone, washed several times with ultrapure water and dried; in the present comparative example, the material is 10 g and the acetone is 100 mL.

[0074] Comparative Example 6

[0075] 1. The recovered waste solid-state polymer lithium ion battery is discharged in salt water, then washed with ultrapure water and dried.

[0076] 2. The battery is manually disassembled to obtain the battery shell, aluminum foil and mixed electrode sheet.

[0077] 3. The mixed electrode sheet is washed several times with dimethyl carbonate and then soaked in ultrapure water to separate the separator containing electrode material from the copper foil, and then dried.

[0078] 4. The separator containing electrode material is cut into small pieces and stirred rapidly in pure water, washed several times with ultrapure water and dried; in the present comparative example, the material is 10 g and the pure water is 100 mL.

[0079] Related test data and comparison:

[0080] The conditions of each example and each comparative example are shown in Table 1.

[0081] Table 1

[0082] Group Reagent Solid-liquid ratio Whether separation Separation efficiency Example 1 N-methylpyrrolidone 10 g / 100 mL Separation 100% Example 2 N-methylpyrrolidone 50 g / 100 mL Separation 100% Example 3 N-methylpyrrolidone 100 g / 100 mL Separation 96% Comparative Example 1 N-methylpyrrolidone 200 g / 100 mL Partial separation 78% Comparative Example 2 N-methylpyrrolidone 300 g / 100 mL Partial separation 52% Comparative Example 3 Dichloromethane 10 g / 100 mL No separation 0% Comparative Example 4 Methanol 10 g / 100 mL No separation 0% Comparative Example 5 Acetone 10 g / 100 mL No separation 0% Comparative Example 6 Pure water 10 g / 100 mL No separation 0%

[0083] From the data in Table 1, it can be seen that:

[0084] In Comparative Example 1 and Comparative Example 2, under the condition of large solid-liquid ratio, there is the disadvantage that the separation efficiency will decrease.

[0085] In Comparative Example 3, when the organic solvent is replaced by dichloromethane, there is the disadvantage that the material and the separator cannot be separated.

[0086] In Comparative Example 4, when the organic solvent is replaced by methanol, there is the disadvantage that the material and the separator cannot be separated.

[0087] In Comparative Example 5, when the organic solvent is replaced by acetone, there is the disadvantage that the material and the separator cannot be separated.

[0088] In Comparative Example 6, when the organic solvent is replaced by pure water, there is the disadvantage that the material and the separator cannot be separated.

[0089] In the embodiments 1-3, the separation efficiency of the electrode material and the separator is close to 100%, and there is no residual separator impurity in the obtained electrode material, compared with the conventional pyrolysis method, the method is realized at room temperature, does not emit harmful gas, can recover the whole component, and the electrode material is not damaged, and can be used for direct regeneration. The present application has the advantages of low cost, simple operation, short process, high economic benefit, green and sustainable, etc.

[0090] The above merely describes preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for separating waste solid polymer lithium-ion battery electrode materials and separators, characterized in that, The method includes: Waste solid polymer lithium-ion batteries are discharged and aluminum foil and copper foil containing electrode materials and separators are obtained by disassembling the waste solid polymer lithium-ion batteries. A copper foil containing electrode material and a diaphragm is subjected to water immersion treatment to obtain copper foil and a diaphragm containing electrode material; The membrane containing electrode material is dissolved by N-methylpyrrolidone to remove solid polymer, and the electrode material attached to the membrane is peeled off. The electrode material and membrane are then obtained by two filtrations. In the step of dissolving the membrane containing electrode material with N-methylpyrrolidone, the membrane containing electrode material is cut into fragments, the fragments are added to N-methylpyrrolidone according to a preset solid-liquid ratio, and stirred to promote the separation of electrode material from the membrane. The preset solid-liquid ratio is 0.1-1 kg / L. In the step of dissolving the membrane containing electrode materials using N-methylpyrrolidone, the compound being dissolved is polyethylene oxide, polysiloxane, polyacrylonitrile, or polymethyl methacrylate.

2. The method for separating waste solid polymer lithium-ion battery electrode materials and separators according to claim 1, characterized in that, The size of the fragments is 1-5cm. 2 The stirring speed is 10-60 revolutions per minute.

3. The method for separating waste solid polymer lithium-ion battery electrode materials and separators according to claim 1, characterized in that, Waste solid polymer lithium-ion batteries are ternary lithium batteries, lithium cobalt oxide batteries, lithium manganese oxide batteries, or Co-Al co-doped lithium nickel oxide batteries.

4. The method for separating waste solid polymer lithium-ion battery electrode materials and separators according to claim 1, characterized in that, In the process of discharging waste solid polymer lithium-ion batteries, the waste solid polymer lithium-ion batteries are placed in salt water for discharge for 12-24 hours. The salt water is a 5%-10% NaCl solution.

5. The method for separating waste solid polymer lithium-ion battery electrode materials and separators according to claim 4, characterized in that, After discharge treatment, the waste solid polymer lithium-ion batteries are cleaned with ultrapure water and then dried.

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