Method for recycling alumina powder from waste lithium battery diaphragm material
By cleaning and ball milling, the problems of alumina powder agglomeration and binder residue are solved, the reuse of alumina powder and the performance of the battery separator are achieved, and the recycling efficiency and electrochemical performance are improved.
Patent Information
- Application Number
- CN202510559426.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-29
- Publication Date
- 2025-08-05
AI Technical Summary
The alumina powder agglomerates in the waste lithium battery separator material, and the adhesive residue is high, so it can no longer be used in lithium battery separator, and the recycling profit is low.
Use a cleaning agent to clean the waste lithium battery separator material, use ionic liquid as a ball mill to ball mill the alumina powder, and calcinate it in an oxygen-containing atmosphere to decompose surface defects and form regular particles.
It realizes effective separation and reuse of alumina powder and the diaphragm, improves electrochemical performance, improves recycling profits, and is environmentally friendly and safe in cleaning agents and is cheap.
Smart Images
Figure CN120423583A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of lithium battery recycling, and in particular to a method for recycling and reusing alumina powder from waste lithium battery diaphragm materials. Background Art
[0002] In recent years, as demand for lithium-ion battery safety has grown, high-purity alumina, due to its high-temperature resistance, corrosion resistance, and insulating properties, has been widely used in lithium battery separators. Furthermore, with the continued expansion of markets for new energy vehicles and energy storage systems, the number of used lithium batteries is expected to increase, creating more business opportunities and space for the recycling industry. Currently, the alumina powder recovered from used lithium battery separators suffers from severe agglomeration and high levels of binder residue, making it unsuitable for use in lithium battery separator production and resulting in low recycling profits. Summary of the Invention
[0003] Purpose of the invention: In response to the above technical problems, the present invention proposes a method for recycling and reusing alumina powder from waste lithium battery separator materials.
[0004] The technical solutions adopted are as follows:
[0005] A method for recycling aluminum oxide powder from waste lithium battery separator materials:
[0006] The slurry obtained by washing the diaphragm material of the waste lithium battery with a cleaning agent is centrifuged, the collected waste alumina powder is washed with water and then dried, and then the waste alumina powder is ball-milled using ionic liquid as a ball-milling aid. After the ball-milling is completed, the solid is collected and calcined in an oxygen-containing atmosphere.
[0007] Furthermore, the oxygen-containing atmosphere is air.
[0008] Furthermore, the cleaning agent is composed of the following:
[0009] Alkyl glycoside 0.5-0.8%, isopropyl alcohol 0.5-1%, sodium citrate 0.1-0.2%, tetrasodium glutamate diacetate 0.05-0.1%, benzotriazole 0.005-0.01%, polyether modified silicone oil 0.01-0.05%, defoaming agent 0.001-0.005%, and the balance is water.
[0010] Furthermore, the bath ratio during cleaning is 1:50-100. The bath ratio is the mass ratio of the diaphragm material to the cleaning agent.
[0011] Furthermore, ultrasonic waves are applied during cleaning.
[0012] Furthermore, the ionic liquid is a chloroaluminate ionic liquid.
[0013] Furthermore, the chloroaluminate ionic liquid is any one or a combination of 1-butyl-3-methylimidazolium chloroaluminate, 1-pentyl-3-methylimidazolium chloroaluminate, 1-hexyl-3-methylimidazolium chloroaluminate, 1-heptyl-3-methylimidazolium chloroaluminate, 1-octyl-3-methylimidazolium chloroaluminate, 1-nonyl-3-methylimidazolium chloroaluminate, and 1-decyl-3-methylimidazolium chloroaluminate.
[0014] Furthermore, the ball milling time is 5-10 hours, and the ball milling speed is 50-100 r / min.
[0015] Furthermore, the amount of the ionic liquid used is 0.1-1% of the mass of the waste alumina powder.
[0016] Furthermore, the calcination temperature is 600-800° C., and the calcination time is 3-5 hours.
[0017] Furthermore, the heating rate during calcination is 1-10°C / min.
[0018] As an essential and key material in lithium batteries, the separator's core function is to separate the positive and negative electrodes, effectively preventing internal short circuits in the battery while allowing the smooth passage of electrolyte ions, thereby completing the electrochemical charge and discharge cycle. The performance of the separator has a decisive influence on the battery's interface structure and internal resistance, which in turn directly affects the battery's capacity, cycle life, and safety. Therefore, a high-performance separator is crucial to improving overall battery performance.
[0019] Inorganic composite modification enhances the performance of polyolefin separators by coating them with a layer of inorganic ceramic particles. This modification not only enhances the separator's wettability and absorption of electrolytes, but also significantly increases its mechanical strength. More importantly, the excellent thermal stability of inorganic ceramic materials effectively prevents the separator from shrinking or melting in high-temperature environments, significantly improving battery life and safety.
[0020] Currently, the most widely used inorganic ceramic particle is aluminum oxide, which dominates high-safety power batteries (such as new energy vehicles) and high-end consumer electronic batteries. However, there are also related studies on other oxides (such as silicon oxide, zirconium oxide, titanium oxide, etc.). When the surface of the polyolefin separator is covered with oxides (such as silicon oxide, zirconium oxide, titanium oxide, etc.), the method of the present invention can also be used as a reference, but it is necessary to replace the ionic liquid with an ionic liquid of the corresponding oxide, such as silicon-based ionic liquids or silicon-containing ionic liquid complexes, zirconium-based ionic liquids or zirconium-containing ionic liquid complexes, titanium-based ionic liquids or titanium-containing ionic liquid complexes.
[0021] In order to reduce the cleaning time or the amount of cleaning agent used, high-pressure water washing or magnetic pulse washing can be used to rinse the waste lithium battery diaphragm material before cleaning, and the easily peeled aluminum oxide can be washed off and collected in advance, thereby achieving the purpose of improving production efficiency.
[0022] It has the following beneficial effects:
[0023] The present invention provides a method for recycling and reusing alumina powder from waste lithium battery diaphragm materials. The waste lithium battery diaphragm materials are cleaned with a cleaning agent, which can separate the alumina particles from the diaphragm, facilitating the recycling of the diaphragm and the alumina particles. The cleaning agent solves the problem of stubborn colloid residue on the surface of the alumina particles and in the pores of the diaphragm through the synergistic effect of "penetration-emulsification-stripping". After cleaning, the diaphragm has high transparency, is safe and environmentally friendly, non-flammable and non-explosive, non-toxic and has no irritating odor. The cleaning agent can be recycled multiple times, is easy to use, and has low cost.
[0024] During ball milling, the chloroaluminate ionic liquid wets and coats the surface of the waste alumina particles through electrostatic action, reducing the van der Waals force between the particles, forming a double-layer repulsion, dynamically maintaining the stability of the particle dispersion, and more efficiently transferring the ball milling energy to the particle surface, promoting the dispersion of the alumina particles. In addition, during subsequent calcination, it can decompose to form alumina to fill the surface defects of the alumina particles, making the particle morphology more regular, thereby maintaining the perfect morphology of the coating during subsequent coating, maintaining good continuity, and can be reused in the production of lithium battery separators while maintaining good electrochemical properties, thereby increasing the additional profit from the recycling and reuse of alumina powder. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 This is a surface SEM image of the coated diaphragm in Example 1;
[0026] Figure 2 This is the surface SEM image of the coated diaphragm in Comparative Example 2. DETAILED DESCRIPTION
[0027] Unless otherwise specified, the following examples and comparative examples were conducted in parallel, using the same processing steps and parameters.
[0028] Example 1:
[0029] A method for recycling aluminum oxide powder from waste lithium battery separator materials:
[0030] The waste lithium-ion battery was discharged, the battery shell was manually peeled off, and the diaphragm material was sorted out. The diaphragm material was added to an ultrasonic mixer and then a cleaning agent was added. The ultrasonic cleaning was carried out at room temperature for 5 hours at a bath ratio of 1:50, with an ultrasonic frequency of (28±2) kHz, a power density of 60 W / L, and a frequency period of 400 ms. The diaphragm material was filtered out and dried, and its transmittance was tested by a haze meter to be 83.6%. The remaining slurry was then centrifuged, and the collected waste alumina powder was rinsed with water and dried and placed in a ball mill. 1-butyl-3-methylimidazolium chloroaluminate, 0.1% of the mass of the waste alumina powder, was added as a ball milling aid, and the mixture was ball milled at a speed of 50 r / min in a planetary ball mill for 5 hours. After the ball milling was completed, the collected solid was heated to 600°C at a rate of 1°C / min in an air atmosphere in a muffle furnace and calcined for 5 hours.
[0031] The composition of the cleaning agent is as follows:
[0032] Alkyl polyglycoside APG-0814 0.6%, isopropyl alcohol 0.8%, sodium citrate 0.15%, tetrasodium glutamate diacetate 0.08%, benzotriazole 0.006%, polyether modified silicone oil DY-ET200 0.02%, defoaming agent BYK-022 0.002%, and the balance is water.
[0033] Electrochemical performance test: First, PVDF, alumina powder and acetone were mixed in a mass ratio of 2:3:5 and stirred at a high speed of 1000r / min for 2h to prepare a coating slurry. The PP microporous membrane was immersed in the slurry and then dried in an oven at 80℃ to obtain a coated membrane. Figure 1 It can be seen that the coating morphology is perfect and the powder particles are clear and uniform;
[0034] LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 material was mixed with CNTs and PVDF in a mass ratio of (90:5:5) to obtain a composite material, which was then prepared into a slurry with NMP. The slurry was evenly coated on aluminum foil, dried in a vacuum at 90°C for 12 hours, and then rolled to obtain a positive electrode sheet.
[0035] The positive electrode sheet was punched into a disc, a metal lithium sheet was used as the counter electrode, and 1 mol / L LiPF6 / DMC+EMC+EC (volume ratio of 1:1:1) was used as the electrolyte. The cells were assembled into button cells in an argon-filled glove box.
[0036] The electrochemical performance of the button battery was tested using a Blue Electric test system. It was activated three times at a low rate of 0.1C and then switched to charge and discharge cycle testing at 1C. After activation at a rate of 0.1C, the initial discharge capacity was 233.6mAh / g. After 100 cycles at 1C, the discharge capacity was 226.1mAh / g, and the capacity retention rate was 96.8%.
[0037] Example 2:
[0038] A method for recycling aluminum oxide powder from waste lithium battery separator materials:
[0039] The waste lithium-ion battery was discharged, the battery shell was manually peeled off, and the diaphragm material was sorted out. The diaphragm material was added to an ultrasonic mixer and then a cleaning agent was added. The ultrasonic cleaning was carried out at room temperature for 5 hours at a bath ratio of 1:100, with an ultrasonic frequency of (28±2)kHz, a power density of 60W / L, and a frequency period of 400ms. The diaphragm material was filtered out and dried, and its transmittance was tested by a haze meter to be 85.8%. The remaining slurry was then centrifuged, and the collected waste alumina powder was rinsed with water and dried and placed in a ball mill. 1% of the mass of the waste alumina powder was added as a ball milling aid, and the mixture was ball milled at a speed of 100r / min in a planetary ball mill for 10 hours. After the ball milling was completed, the collected solid was heated to 800℃ in a muffle furnace at a rate of 10℃ / min in an air atmosphere and calcined for 3 hours.
[0040] The composition of the cleaning agent is as follows:
[0041] Alkyl glycoside 0.6%, isopropyl alcohol 0.8%, sodium citrate 0.15%, tetrasodium glutamate diacetate 0.08%, benzotriazole 0.006%, polyether modified silicone oil DY-ET200 0.02%, defoaming agent BYK-022 0.002%, and the balance is water.
[0042] Electrochemical performance test: PVDF, alumina powder, and acetone were mixed in a mass ratio of 2:3:5 and stirred at 1000 rpm for 2 hours to prepare a coating slurry. The PP microporous membrane was immersed in the slurry and then dried in an 80°C oven to obtain a coated membrane.
[0043] LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 material was mixed with CNTs and PVDF in a mass ratio of (90:5:5) to obtain a composite material, which was then prepared into a slurry with NMP. The slurry was evenly coated on aluminum foil, dried in a vacuum at 90°C for 12 hours, and then rolled to obtain a positive electrode sheet.
[0044] The positive electrode sheet was punched into a disc, a metal lithium sheet was used as the counter electrode, and 1 mol / L LiPF6 / DMC+EMC+EC (volume ratio of 1:1:1) was used as the electrolyte. The cells were assembled into button cells in an argon-filled glove box.
[0045] The electrochemical performance of the button battery was tested using the Blue Electric test system. It was activated three times at a low rate of 0.1C and then switched to charge and discharge cycle testing at 1C. After activation at a rate of 0.1C, the first discharge capacity was 245.8mAh / g. After 100 cycles at 1C, the discharge capacity was 239.2mAh / g, and the capacity retention rate was 97.3%.
[0046] Example 3:
[0047] A method for recycling aluminum oxide powder from waste lithium battery separator materials:
[0048] The waste lithium-ion battery is discharged, the battery shell is manually peeled off, and the diaphragm material is sorted out. The diaphragm material is added to an ultrasonic mixer and then a cleaning agent is added. The ultrasonic cleaning is carried out at room temperature for 5 hours at a bath ratio of 1:80, with an ultrasonic frequency of (28±2) kHz, a power density of 60 W / L, and a frequency period of 400 ms. The diaphragm material is filtered out and dried, and its transmittance is tested by a haze meter to be 84.4%. The remaining slurry is then centrifuged, and the collected waste alumina powder is rinsed with water and dried and placed in a ball mill jar. 1-butyl-3-methylimidazolium chloroaluminate, 0.5% of the mass of the waste alumina powder, is added as a ball milling aid, and the mixture is ball milled at a speed of 80 r / min in a planetary ball mill for 6 hours. After the ball milling is completed, the collected solid is heated to 700°C at a rate of 5°C / min in an air atmosphere in a muffle furnace and calcined for 4 hours.
[0049] The composition of the cleaning agent is as follows:
[0050] Alkyl glycoside 0.6%, isopropyl alcohol 0.8%, sodium citrate 0.15%, tetrasodium glutamate diacetate 0.08%, benzotriazole 0.006%, polyether modified silicone oil DY-ET200 0.02%, defoaming agent BYK-022 0.002%, and the balance is water.
[0051] Electrochemical performance test: PVDF, alumina powder, and acetone were mixed in a mass ratio of 2:3:5 and stirred at 1000 rpm for 2 hours to prepare a coating slurry. The PP microporous membrane was immersed in the slurry and then dried in an 80°C oven to obtain a coated membrane.
[0052] LiNi 1 / 3 Co 1 / 3 Mn 1 / 3O2 material was mixed with CNTs and PVDF in a mass ratio of (90:5:5) to obtain a composite material, which was then prepared into a slurry with NMP. The slurry was evenly coated on aluminum foil, dried in a vacuum at 90°C for 12 hours, and then rolled to obtain a positive electrode sheet.
[0053] The positive electrode sheet was punched into a disc, a metal lithium sheet was used as the counter electrode, and 1 mol / L LiPF6 / DMC+EMC+EC (volume ratio of 1:1:1) was used as the electrolyte. The cells were assembled into button cells in an argon-filled glove box.
[0054] The electrochemical performance of the button battery was tested using a blue electric test system. It was activated three times at a low rate of 0.1C and then switched to charge and discharge cycle testing at 1C. After activation at a rate of 0.1C, the initial discharge capacity was 250.5mAh / g. After 100 cycles at 1C, the discharge capacity was 244.7mAh / g, and the capacity retention rate was 97.7%.
[0055] Example 4:
[0056] A method for recycling aluminum oxide powder from waste lithium battery separator materials:
[0057] The waste lithium-ion battery was discharged, the battery shell was manually peeled off, and the diaphragm material was sorted out. The diaphragm material was added to an ultrasonic mixer and then a cleaning agent was added. The ultrasonic cleaning was carried out at room temperature for 5 hours at a bath ratio of 1:80, with an ultrasonic frequency of (28±2) kHz, a power density of 60 W / L, and a frequency period of 400 ms. The diaphragm material was filtered out and dried, and its transmittance was tested by a haze meter to be 80.2%. The remaining slurry was then centrifuged, and the collected waste alumina powder was rinsed with water and dried and placed in a ball mill jar. 1-butyl-3-methylimidazolium chloroaluminate, 0.5% of the mass of the waste alumina powder, was added as a ball milling aid, and the mixture was ball milled at a speed of 80 r / min in a planetary ball mill for 6 hours. After the ball milling was completed, the collected solid was heated to 700°C at a rate of 5°C / min in an air atmosphere in a muffle furnace and calcined for 4 hours.
[0058] The composition of the cleaning agent is as follows:
[0059] Alkyl glycoside 0.5%, isopropyl alcohol 0.5%, sodium citrate 0.1%, tetrasodium glutamate diacetate 0.05%, benzotriazole 0.005%, polyether modified silicone oil DY-ET200 0.01%, defoaming agent BYK-022 0.001%, and the balance is water.
[0060] Example 5:
[0061] A method for recycling aluminum oxide powder from waste lithium battery separator materials:
[0062] The waste lithium-ion battery is discharged, the battery shell is manually peeled off, and the diaphragm material is sorted out. The diaphragm material is added to an ultrasonic mixer and then a cleaning agent is added. The ultrasonic cleaning is carried out at room temperature for 5 hours at a bath ratio of 1:80, with an ultrasonic frequency of (28±2) kHz, a power density of 60 W / L, and a frequency period of 400 ms. The diaphragm material is filtered out and dried, and its transmittance is tested by a haze meter to be 86.3%. The remaining slurry is then centrifuged, and the collected waste alumina powder is rinsed with water and dried and placed in a ball mill jar. 1-butyl-3-methylimidazolium chloroaluminate, 0.5% of the mass of the waste alumina powder, is added as a ball milling aid, and the mixture is ball milled at a speed of 80 r / min in a planetary ball mill for 6 hours. After the ball milling is completed, the collected solid is heated to 700°C at a rate of 5°C / min in an air atmosphere in a muffle furnace and calcined for 4 hours.
[0063] The composition of the cleaning agent is as follows:
[0064] Alkyl glycoside 0.8%, isopropyl alcohol 1%, sodium citrate 0.2%, tetrasodium glutamate diacetate 0.1%, benzotriazole 0.01%, polyether modified silicone oil DY-ET200 0.05%, defoaming agent BYK-022 0.005%, and the balance is water.
[0065] Comparative Example 1:
[0066] The method is basically the same as Example 1, except that the commercially available lithium battery diaphragm cleaning agent H426 is diluted five times and replaced with the cleaning agent. After the diaphragm material is filtered out and dried, the light transmittance thereof is tested using a haze meter and is 74.1%.
[0067] By comparison with Example 1, it can be seen that the cleaning effect of the cleaning agent of the present invention is better than that of the commercially available lithium battery separator cleaning agent.
[0068] Comparative Example 2:
[0069] The method is basically the same as Example 1, except that the waste alumina powder is directly used to prepare the coated diaphragm without being ball-milled or calcined.
[0070] Electrochemical performance test: First, PVDF, alumina powder and acetone were mixed in a mass ratio of 2:3:5 and stirred at a high speed of 1000r / min for 2h to prepare a coating slurry. The PP microporous membrane was immersed in the slurry and then dried in an oven at 80℃ to obtain a coated membrane. Figure 2 It can be seen that the coated particles are uneven in size, severely agglomerated, the pores formed by solvent evaporation are unevenly distributed, and the structural continuity is poor;
[0071] LiNi 1 / 3 Co 1 / 3 Mn 1 / 3O2 material was mixed with CNTs and PVDF in a mass ratio of (90:5:5) to obtain a composite material, which was then prepared into a slurry with NMP. The slurry was evenly coated on aluminum foil, dried in a vacuum at 90°C for 12 hours, and then rolled to obtain a positive electrode sheet.
[0072] The positive electrode sheet was punched into a disc, a metal lithium sheet was used as the counter electrode, and 1 mol / L LiPF6 / DMC+EMC+EC (volume ratio of 1:1:1) was used as the electrolyte. The cells were assembled into button cells in an argon-filled glove box.
[0073] The electrochemical performance of the button battery was tested using the Blue Electric test system. It was activated three times at a low rate of 0.1C and then switched to charge and discharge cycle testing at 1C. After activation at a rate of 0.1C, the initial discharge capacity was 169.5mAh / g. After 100 cycles at 1C, the discharge capacity was 38.6mAh / g, and the capacity retention rate was 22.8%.
[0074] By comparison with Example 1, it can be seen that the application effect of directly recycling waste alumina powder for preparing coated diaphragms is not good.
[0075] Comparative Example 3:
[0076] The process is basically the same as Example 1, except that 1-butyl-3-methylimidazolium chloride is used instead of 1-butyl-3-methylimidazolium chloroaluminate as the ball milling aid.
[0077] Electrochemical performance test: PVDF, alumina powder, and acetone were mixed in a mass ratio of 2:3:5 and stirred at 1000 rpm for 2 hours to prepare a coating slurry. The PP microporous membrane was immersed in the slurry and then dried in an 80°C oven to obtain a coated membrane.
[0078] LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 material was mixed with CNTs and PVDF in a mass ratio of (90:5:5) to obtain a composite material, which was then prepared into a slurry with NMP. The slurry was evenly coated on aluminum foil, dried in a vacuum at 90°C for 12 hours, and then rolled to obtain a positive electrode sheet.
[0079] The positive electrode sheet was punched into a disc, a metal lithium sheet was used as the counter electrode, and 1 mol / L LiPF6 / DMC+EMC+EC (volume ratio of 1:1:1) was used as the electrolyte. The cells were assembled into button cells in an argon-filled glove box.
[0080] The electrochemical performance of the button battery was tested using the Blue Electric test system. It was activated three times at a low rate of 0.1C and then switched to charge and discharge cycle testing at 1C. After activation at a rate of 0.1C, the initial discharge capacity was 188.6mAh / g. After 100 cycles at 1C, the discharge capacity was 85.4mAh / g, and the capacity retention rate was 43.3%.
[0081] By comparison with Example 1, it can be seen that the use of 1-butyl-3-methylimidazolium chloroaluminate as a ball milling aid in the present invention plays a significant role in improving the recycling and application value of waste alumina powder.
[0082] Comparative Example 4:
[0083] The process is basically the same as Example 1, except that fresh commercially available alumina powder is used instead of the recycled alumina powder.
[0084] Electrochemical performance test: PVDF, alumina powder, and acetone were mixed in a mass ratio of 2:3:5 and stirred at 1000 rpm for 2 hours to prepare a coating slurry. The PP microporous membrane was immersed in the slurry and then dried in an 80°C oven to obtain a coated membrane.
[0085] LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 material was mixed with CNTs and PVDF in a mass ratio of (90:5:5) to obtain a composite material, which was then prepared into a slurry with NMP. The slurry was evenly coated on aluminum foil, dried in a vacuum at 90°C for 12 hours, and then rolled to obtain a positive electrode sheet.
[0086] The positive electrode sheet was punched into a disc, a metal lithium sheet was used as the counter electrode, and 1 mol / L LiPF6 / DMC+EMC+EC (volume ratio of 1:1:1) was used as the electrolyte. The cells were assembled into button cells in an argon-filled glove box.
[0087] The electrochemical performance of the button battery was tested using the Blue Electric test system. It was activated three times at a low rate of 0.1C and then switched to charge and discharge cycle testing at 1C. After activation at a rate of 0.1C, the first discharge capacity was 255.3mAh / g. After 100 cycles at 1C, the discharge capacity was 251.5mAh / g, and the capacity retention rate was 98.5%.
[0088] By comparison with Example 1, it can be seen that the actual application effect of the recycled alumina powder of the present invention is close to that of fresh commercially available alumina powder.
[0089] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.
Claims
1. A method for recycling alumina powder from waste lithium battery separator materials, characterized in that: The details are as follows: The slurry obtained by washing the diaphragm material of the waste lithium battery with a cleaning agent is centrifuged, the collected waste alumina powder is washed with water and then dried, and then the waste alumina powder is ball-milled using ionic liquid as a ball-milling aid. After the ball-milling is completed, the solid is collected and calcined in an oxygen-containing atmosphere.
2. The method for recycling alumina powder from waste lithium battery separator materials according to claim 1, characterized in that: The composition of the cleaning agent is as follows: Alkyl glycoside 0.5-0.8%, isopropyl alcohol 0.5-1%, sodium citrate 0.1-0.2%, tetrasodium glutamate diacetate 0.05-0.1%, benzotriazole 0.005-0.01%, polyether modified silicone oil 0.01-0.05%, defoaming agent 0.001-0.005%, and the balance is water.
3. The method for recycling alumina powder from waste lithium battery separator materials according to claim 1, characterized in that: The bath ratio during cleaning is 1:50-100.
4. The method for recycling alumina powder from waste lithium battery separator materials according to claim 1, characterized in that: Ultrasonic waves are applied during cleaning.
5. The method for recycling alumina powder from waste lithium battery separator materials according to claim 1, characterized in that: The ionic liquid is a chloroaluminate ionic liquid.
6. The method for recycling alumina powder from waste lithium battery separator materials according to claim 5, characterized in that: The chloroaluminate ionic liquid is any one or a combination of 1-butyl-3-methylimidazolium chloroaluminate, 1-pentyl-3-methylimidazolium chloroaluminate, 1-hexyl-3-methylimidazolium chloroaluminate, 1-heptyl-3-methylimidazolium chloroaluminate, 1-octyl-3-methylimidazolium chloroaluminate, 1-nonyl-3-methylimidazolium chloroaluminate, and 1-decyl-3-methylimidazolium chloroaluminate.
7. The method for recycling alumina powder from waste lithium battery separator materials according to claim 1, characterized in that: The ball milling time is 5-10h, and the ball milling speed is 50-100r / min.
8. The method for recycling alumina powder from waste lithium battery separator materials according to claim 1, characterized in that: The amount of the ionic liquid used is 0.1-1% of the mass of the waste alumina powder.
9. The method for recycling alumina powder from waste lithium battery separator materials according to claim 1, characterized in that: The calcination temperature is 600-800°C, and the calcination time is 3-5h.
10. The method for recycling alumina powder from waste lithium battery separator materials according to claim 1, characterized in that: The heating rate during calcination is 1-10°C / min.