A method for recycling waste lithium battery positive electrode materials through high voltage pulse

Abstract

This disclosure pertains to the field of waste battery recycling technology, specifically relating to a method for recycling waste lithium battery cathode materials using high-voltage pulses. This disclosure employs a combination of high-voltage pulses and ultraviolet irradiation to break down waste cathode sheets, effectively separating the titanium dioxide-coated cathode material from the cathode current collector (such as aluminum foil), significantly improving the separation rate, and resulting in very low aluminum content in the separated cathode material.

Description

Technical Field

[0001] This disclosure belongs to the field of waste battery recycling technology, and specifically relates to a method for recycling the positive electrode material of waste lithium batteries through high-voltage pulse. Background Technology

[0002] With the rapid development of new energy vehicles, the shipment volume of power batteries in China continues to increase. Due to the limited lifespan of batteries, a large number of waste lithium-ion batteries are generated. These waste lithium-ion batteries contain large amounts of valuable metals such as nickel, cobalt, manganese, and lithium, as well as toxic substances such as lithium hexafluorophosphate. Improper handling can easily lead to resource waste and environmental pollution. Currently, lithium-ion battery recycling technologies mainly focus on hydrometallurgy, pyrometallurgy, and combined hydrometallurgical and pyrometallurgical recycling. Hydrometallurgy mainly involves dissolving valuable metals through acid leaching, followed by extraction or precipitation to remove the remaining valuable metal elements. This method requires a large amount of acid leaching reagent, resulting in high costs and potential environmental pollution. Pyrometallurgy, on the other hand, removes organic matter and binders through high-temperature calcination, followed by sieving and magnetic separation to obtain the product. However, this method is prone to introducing impurities such as copper and aluminum and has high energy consumption.

[0003] In many discarded lithium-ion batteries, the cathode materials have been modified through coating. This coating modification method can improve the electrochemical performance of the cathode materials. Titanium dioxide, as an excellent coating material, has the characteristics of strong adhesion and stable chemical properties, and is often used for the coating modification of cathode materials, thereby giving them superior electrochemical performance.

[0004] However, if titanium dioxide-coated materials are recycled using hydrometallurgical or pyrometallurgical methods, the coating layer will transform into impurities in valuable metals, making the recycled material difficult to reuse. Therefore, there is an urgent need to develop a method for directly recycling titanium dioxide-coated cathode materials.

[0005] In view of this, this disclosure is hereby made. Summary of the Invention

[0006] The purpose of this disclosure is to provide a method for recycling waste lithium battery cathode materials through high-voltage pulses, aiming to effectively separate the cathode materials while ensuring the recovery rate and controlling the aluminum content of impurities.

[0007] To achieve the above-mentioned objectives of this disclosure, the following technical solutions may be adopted:

[0008] The solution provided in this disclosure includes a method for recycling waste lithium battery cathode materials through high-voltage pulses, comprising: crushing the waste cathode sheets under the synergistic effect of high-voltage pulses and ultraviolet light irradiation;

[0009] The cathode material in the waste cathode sheet includes a cathode material matrix and a coating layer covering the cathode material matrix, and the coating layer contains titanium dioxide.

[0010] In some embodiments of this disclosure, the voltage of the applied high-voltage electrical pulse is 100kV-180kV.

[0011] In some embodiments of this disclosure, the voltage of the applied high-voltage electrical pulse is 120kV-150kV.

[0012] In some embodiments of this disclosure, the waste positive electrode sheet is first crushed once, and then placed in a high-voltage pulse crusher for secondary crushing, during which ultraviolet light is applied.

[0013] In some embodiments of this disclosure, during the secondary crushing process, the electrode spacing is controlled to be 5mm-10mm and the number of pulses is 300-400.

[0014] In some embodiments of this disclosure, during the secondary crushing process, the electrode spacing is controlled to be 6mm-10mm and the number of pulses is 300-350.

[0015] In some embodiments of this disclosure, water is used as the medium during the secondary crushing process, and the discharge frequency is controlled to be 2Hz-5Hz.

[0016] In some embodiments of this disclosure, the applied ultraviolet light has a dominant wavelength of 200nm-380nm and an irradiance of 12mW / cm². 2 ~36mW / cm 2 .

[0017] In some embodiments of this disclosure, the applied ultraviolet light has a dominant wavelength of 350nm-380nm and an irradiance of 15mW / cm². 2 ~25mW / cm 2 .

[0018] In some embodiments of this disclosure, primary crushing involves crushing the waste positive electrode sheet to 10mm-50mm.

[0019] In some embodiments of this disclosure, the cathode material matrix is ​​selected from at least one of lithium iron phosphate, lithium manganese iron phosphate, lithium nickel cobalt manganese oxide, and lithium cobalt oxide.

[0020] In some embodiments of this disclosure, the positive current collector in the waste positive electrode sheet is aluminum foil, and the waste positive electrode sheet contains at least one of polyvinylidene fluoride, styrene-butadiene latex, and polytetrafluoroethylene.

[0021] In some embodiments of this disclosure, the method further includes: after crushing the waste positive electrode sheet under high voltage pulse and ultraviolet light conditions, the crushed material is post-processed to obtain positive electrode material powder.

[0022] In some embodiments of this disclosure, post-processing includes drying and sorting the crushed material sequentially to remove fragments from the current collector.

[0023] In some embodiments of this disclosure, during the drying process, the drying temperature is controlled at 50℃-80℃ and the drying time is 6h-24h.

[0024] In some embodiments of this disclosure, sorting is performed using a combination of wind sorting and screening.

[0025] In some embodiments of this disclosure, a 50-100 mesh sieve is used for screening.

[0026] In some embodiments of this disclosure, the method further includes: sieving the undersize powder obtained from sorting through a 300-500 mesh vibrating screen to obtain positive electrode material powder.

[0027] In some embodiments of this disclosure, the method further includes: mixing and sintering the obtained cathode material powder with a lithium source to obtain a recycled cathode material.

[0028] In some embodiments of this disclosure, during the preparation of the regenerated cathode material, a first sintering is performed at 450°C-650°C, followed by a second sintering at 700°C-1000°C.

[0029] In some embodiments of this disclosure, the sintering time for a single sintering is 1-6 hours.

[0030] In some embodiments of this disclosure, the temperature is increased to the sintering temperature for primary sintering at a heating rate of 2°C / min to 10°C / min.

[0031] In some embodiments of this disclosure, the sintering time for the secondary sintering is 6h-12h.

[0032] In some embodiments of this disclosure, by controlling the amount of lithium source used, the molar ratio of lithium content to the total amount of other metal elements in the mixture is 1.01-1.03:1.

[0033] In some embodiments of this disclosure, the lithium source is selected from at least one of lithium hydroxide and lithium carbonate.

[0034] Using high-voltage electric pulse combined with ultraviolet light to crush waste positive electrode sheets can effectively separate the titanium dioxide-coated positive electrode material from the positive electrode current collector (such as aluminum foil), and the separation rate is significantly improved. The aluminum content in the separated positive electrode material is very low.

[0035] It should be noted that using high-voltage electric pulses combined with ultraviolet light irradiation for fragmentation can both ensure the stripping rate of the cathode material and reduce the aluminum content in the cathode material. This is likely based on the following principle:

[0036] Under ultraviolet light, the electrons generated by titanium dioxide gain additional energy under the action of an external electric field, allowing them to penetrate the potential barrier. The avalanche current generated by the charge carriers creates a large number of conductive channels at the interface. Within these conductive channels, a large amount of plasma exists. During the expansion of the plasma, the conductive channels are distributed in a dendritic pattern on the interface, causing the interface between the positive electrode material and the positive electrode current collector (such as aluminum foil) to dissociate, resulting in a fragmented product containing the positive electrode current collector and positive electrode powder.

[0037] Furthermore, titanium dioxide generates a large number of holes under ultraviolet light irradiation. These holes have a strong oxidizing effect and can, to some extent, oxidize the bonds of binders (such as polyvinylidene fluoride, PVDF). However, due to the relative stability of PVDF, oxidation of PVDF by holes alone is inefficient. The external electric field of a high-voltage pulse promotes electron movement, not only allowing more electrons to participate in the interfacial dissociation between the cathode material and the cathode current collector (such as aluminum foil), but also causing more electrons to migrate rather than recombine with holes, thus generating a large number of holes and promoting the oxidation and bond breaking of PVDF. Therefore, under the synergistic effect of ultraviolet light and high-voltage pulse, the peeling rate between titanium dioxide-coated cathode material and cathode current collector (such as aluminum foil) is improved, and the aluminum impurity content of the peeled cathode material is low. Attached Figure Description

[0038] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this disclosure and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a flowchart for the recycling of cathode materials from waste lithium-ion batteries provided in this disclosure.

[0040] Figure 2 This is a photograph of the actual recycled cathode material from Example 1. Detailed Implementation

[0041] The embodiments of this disclosure will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of this disclosure. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0042] The endpoints and any values ​​of the ranges disclosed in this disclosure are not limited to the precise ranges or values, and such ranges or values ​​should be understood to include values ​​close to such ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed herein.

[0043] This disclosure provides a method for recycling spent lithium battery cathode materials using high-voltage pulses, such as... Figure 1 As shown, it includes the following steps:

[0044] S1, Primary crushing (coarse crushing)

[0045] The waste positive electrode sheet is first crushed to obtain smaller-sized fragments, which allows for better separation of the positive electrode material and the positive electrode current collector during the secondary crushing. The primary crushing is an optional step; if the positive electrode sheet itself is small, it is not necessary; for larger sheets, the secondary crushing time can be increased, which can also improve the separation effect.

[0046] Specifically, waste cathode sheets are obtained by discharging and dismantling waste lithium-ion batteries to separate the waste cathode sheets. The cathode material in the waste cathode sheets includes a cathode material matrix and a coating layer covering the cathode material matrix. The coating layer contains titanium dioxide. The method provided in this disclosure is mainly for the recycling of titanium dioxide-coated cathode materials.

[0047] The cathode material matrix is ​​selected from at least one of lithium iron phosphate, lithium manganese iron phosphate, lithium nickel cobalt manganese oxide, and lithium cobalt oxide. It can be any one or more of the above, such as titanium dioxide-coated lithium iron phosphate, titanium dioxide-coated lithium manganese iron phosphate, titanium dioxide-coated lithium nickel cobalt manganese oxide, titanium dioxide-coated lithium cobalt oxide, etc.

[0048] Furthermore, the positive current collector in the waste positive electrode sheet is aluminum foil, and the waste positive electrode sheet contains at least one of polyvinylidene fluoride (PVDF), styrene-butadiene latex (SBR), and polytetrafluoroethylene (PTFE). PVDF and other binders are introduced during the preparation of the positive electrode slurry; PVDF enables the positive electrode active coating to bond better to the positive electrode current collector.

[0049] In some embodiments, primary crushing involves crushing the waste positive electrode sheet to 10mm-50mm, such as 10mm, 20mm, 30mm, 40mm, 50mm, etc. Existing crushers can be used for crushing, such as jaw crushers, impact crushers, shear crushers, etc.

[0050] S2, Secondary Crushing (High-Pressure Pulse Crushing Combined with Ultraviolet Irradiation)

[0051] Waste cathode sheets are subjected to secondary crushing under the synergistic effect of high-voltage electric pulses and ultraviolet light irradiation. In actual operation, the material can be placed in a high-voltage pulse crusher for secondary crushing, during which ultraviolet light irradiation is applied. Using high-voltage electric pulses combined with ultraviolet light irradiation for crushing ensures both the stripping rate of the cathode material and a lower aluminum content in the cathode material.

[0052] Specifically, the high-voltage pulse crusher is an existing crushing instrument. Its crushing mechanism is as follows: Under the action of high-voltage pulse discharge, due to the different dielectric constants of different components inside the material, the electric field strength between different material interfaces is enhanced, resulting in electrical breakdown and the formation of a conductive channel. The large amount of high-temperature and high-pressure plasma generated in the conductive channel causes the channel to expand, leading to the dissociation of different materials along the interface.

[0053] In this embodiment, the working principle of high-voltage pulse fragmentation combined with ultraviolet irradiation is utilized: electrons generated by titanium dioxide under ultraviolet light gain additional energy under the action of an external electric field, allowing them to penetrate the potential barrier. The avalanche current generated by the charge carriers produces a large number of conductive channels at the interface, and a large amount of plasma exists within these conductive channels. During the plasma expansion process, the conductive channels are distributed in a dendritic pattern on the interface, thereby causing the interface between the positive electrode material and the positive electrode current collector (such as aluminum foil) to dissociate, resulting in fragmented products containing the positive electrode current collector (such as aluminum foil) and positive electrode powder. In addition, titanium dioxide generates a large number of holes under ultraviolet light irradiation. These holes have a strong oxidizing effect and can oxidize the binder (such as polyvinylidene fluoride, PVDF) to a certain extent, breaking the bonds. However, since PVDF is relatively stable, the efficiency of oxidizing PVDF by holes alone is low. The external electric field of the high-voltage pulse promotes electron movement, not only allowing more electrons to participate in the interface dissociation between the positive electrode material and the positive electrode current collector (such as aluminum foil), but also causing more electrons to migrate rather than recombine with holes, thus promoting the generation of a large number of holes and facilitating the oxidation and bond breaking of PVDF. Therefore, under the synergistic effect of ultraviolet light and high voltage pulse, the peeling rate between titanium dioxide coated cathode material and cathode current collector is improved, and the aluminum impurity content of the peeled cathode material is low.

[0054] In some embodiments, the applied high-voltage electric pulse has a voltage of 100kV-180kV, preferably 120kV-150kV. If the applied voltage is too low, it will affect the stripping effect; if the applied voltage is too high, it will affect the stability of the equipment. Specifically, the applied high-voltage electric pulse voltage can be 100kV, 110kV, 120kV, 130kV, 140kV, 150kV, 160kV, 170kV, 180kV, etc.

[0055] Furthermore, during the secondary crushing process, the electrode spacing is controlled at 5mm-10mm, and the number of pulses is 300-400; preferably, the electrode spacing is controlled at 6mm-10mm, and the number of pulses is 300-350. Controlling the electrode spacing within the above range results in better peeling performance. The number of pulses refers to the number of times the waste electrode sheet is repeatedly discharged; controlling it within the above range results in better peeling performance. If the number of pulses is too small, the peeling effect will be reduced; if the number of pulses is too large, it will not further improve the peeling effect and will also increase costs.

[0056] Specifically, during the secondary crushing process, the distance between control electrodes can be 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, etc., and the number of pulses can be 300, 320, 350, 370, 400, etc.

[0057] In some implementations, during the secondary crushing process, water is used as the discharge carrier. Under the influence of a high electric field, a plasma discharge channel is generated inside the water medium, thereby opening the discharge circuit and releasing energy in a short time. The shock wave pressure generated by the expansion of the discharge plasma through the electrode gap causes the solid to break down. During the secondary crushing process, the discharge frequency is controlled at 2Hz-5Hz, such as 2Hz, 3Hz, 4Hz, 5Hz, etc. If the discharge frequency is too high, it will affect the stability of the equipment operation.

[0058] In some embodiments, the applied ultraviolet light has a dominant wavelength of 200nm-380nm and an irradiance of 12mW / cm². 2 ~36mW / cm 2 Preferably, the applied ultraviolet light has a dominant wavelength of 350nm-380nm and an irradiance of 15mW / cm². 2 ~25mW / cm 2 Applying ultraviolet light to the high-pressure pulse crusher using an ultraviolet lamp, with the main wavelength and light intensity controlled within the aforementioned range, can further enhance the stripping effect.

[0059] Specifically, the applied ultraviolet light wavelength can be 200nm, 250nm, 300nm, 350nm, 380nm, etc., and the light intensity can be 12mW / cm². 2 15mW / cm 220mW / cm 2 25mW / cm 2 30mW / cm 2 36mW / cm 2 wait.

[0060] S3, Post-processing

[0061] After the waste positive electrode sheets are crushed under high voltage pulse and ultraviolet light, the crushed material is post-processed to obtain positive electrode material powder, so that the positive electrode material can be reused.

[0062] In some embodiments, post-processing includes sequentially drying and sorting the crushed material to remove current collector fragments. Drying removes moisture from the material surface, and sorting separates the current collector fragments from the positive electrode material, which is mainly in powder form.

[0063] In some implementations, the drying temperature is controlled at 50℃-80℃ and the drying time is 6h-24h. Specifically, the drying temperature can be 50℃, 60℃, 70℃, 80℃, etc., and the drying time can be 6h, 10h, 15h, 20h, 24h, etc.

[0064] In some implementations, the sorting process combines air separation and screening. Air separation can be performed first, followed by screening, or vice versa. Air separation utilizes an air separator, while screening uses sieves for sieving.

[0065] In some implementations, a 50-100 mesh sieve is used for screening to remove large particles of current collector debris. The mesh size of the sieve can be 50, 60, 70, 80, 90, 100, etc.

[0066] In some embodiments, after sorting is completed, the process further includes: passing the sorted undersize powder through a 300-500 mesh vibrating screen to obtain cathode material powder with smaller particle size for use in preparing regenerated cathode materials. The mesh size of the vibrating screen can be 300 mesh, 400 mesh, 500 mesh, etc.

[0067] S4, Lithium Recharge and Regeneration

[0068] The obtained cathode material powder is mixed with a lithium source and sintered to obtain a recycled cathode material. The recycled cathode material still has good electrochemical performance, which improves the utilization value of waste cathode sheets.

[0069] In some embodiments, during the preparation of the recycled cathode material, a first sintering is performed at 450℃-650℃ for 1-6 hours, followed by a second sintering at 700℃-1000℃ for 6-12 hours. This two-stage sintering process further improves the electrochemical performance of the recycled cathode material.

[0070] Specifically, the temperature for the first sintering can be 450℃, 500℃, 550℃, 600℃, 650℃, etc., and the sintering time for the first sintering can be 1h, 2h, 3h, 4h, 5h, 6h, etc.; the temperature for the second sintering can be 700℃, 800℃, 900℃, 1000℃, etc., and the sintering time for the second sintering can be 6h, 8h, 10h, 12h, etc.

[0071] In some embodiments, the temperature is increased to the sintering temperature for the first sintering at a heating rate of 2℃ / min to 10℃ / min, ensuring uniform heating and preventing the heating rate from being too fast. Specifically, the heating rate can be 2℃ / min, 5℃ / min, 7℃ / min, 10℃ / min, etc.

[0072] In some embodiments, by controlling the amount of lithium source used, the molar ratio of lithium content to the total amount of other valuable metal elements in the mixture to be sintered is made to be 1.01-1.03:1, such as 1.01:1, 1.02:1, 1.03:1, etc. The lithium source is selected from at least one of lithium hydroxide and lithium carbonate, and can be any one or more of the above.

[0073] Using high-voltage electric pulse combined with ultraviolet light to crush waste positive electrode sheets can effectively separate the titanium dioxide-coated positive electrode material from the positive electrode current collector (such as aluminum foil), and the separation rate is significantly improved. The aluminum content in the separated positive electrode material is very low.

[0074] The features and performance of this disclosure will be further described in detail below with reference to embodiments.

[0075] It should be noted that the waste positive electrode sheets used in the following examples or comparative examples are of the same type, the positive electrode current collector is an aluminum foil with a thickness of 100-200 μm; the positive electrode material is lithium nickel cobalt manganese oxide (NCM523) coated with titanium dioxide, and the coating amount of titanium dioxide is 1% to 20% of the mass of the positive electrode material; the waste positive electrode sheets also contain PVDF binder, with a content of about 1% to 10% of the mass of the positive electrode material.

[0076] Example 1

[0077] This embodiment provides a method for recycling spent lithium battery cathode materials using high-voltage pulses, including the following steps:

[0078] (1) Use a twin-shaft crusher to coarsely crush the waste positive electrode sheets to a median particle size of about 30mm.

[0079] (2) Transfer the crushed material from step (1) to a high-pressure pulse crusher. Use water as the medium, apply a voltage of 130kV, control the electrode spacing to be 8mm, the discharge frequency to be 4Hz, the number of pulses to be 300, and simultaneously apply ultraviolet light irradiation. The main wavelength of the ultraviolet lamp is 380nm, and the light intensity is 20mW / cm². 2 .

[0080] (3) The crushed material from step (2) is dried at 60°C for 12 hours, then separated through a 50-mesh sieve to remove large particles of current collector fragments. The undersize powder is then sieved through a 300-mesh vibrating screen to obtain the positive electrode material powder, such as... Figure 2 As shown.

[0081] Example 2

[0082] This embodiment provides a method for recycling waste lithium battery cathode materials through high-voltage pulses. Based on steps (1)-(3) of Embodiment 1, step (4) is added. The specific steps of step (4) are as follows:

[0083] The elemental content in the cathode material was determined by ICP. The obtained cathode material powder was mixed with lithium hydroxide, and a lithium source was added so that the molar ratio of lithium ions in the mixture to the total molar ratio of other valuable metals in the cathode material powder was 1.02:1. After mixing evenly, the mixture was heated to 500℃ at a heating rate of 5℃ / min and sintered for 4 hours, and then heated to 800℃ and sintered for 10 hours to obtain the regenerated cathode material.

[0084] Regenerated positive electrode material was uniformly mixed with conductive acetylene black, PVDF, and NMP at a mass ratio of 90:5:5:30 to obtain a positive electrode slurry. The positive electrode slurry was coated onto aluminum foil to a thickness of approximately 50 μm and dried to obtain a positive electrode sheet. A coin cell was fabricated in an argon glove box using a lithium sheet as the negative electrode and the positive electrode sheet as the positive electrode. The discharge capacity at 0.2C was 168.84 mAh / g, and after 100 cycles, the discharge capacity was 159.73 mAh / g, with a capacity retention of 94.61%.

[0085] Example 3

[0086] This embodiment provides a method for recycling waste lithium battery cathode materials using high-voltage pulses. The only difference from Embodiment 1 is that the operating parameters in step (2) are different, as follows:

[0087] The crushed material from step (1) is transferred to a high-pressure pulse crusher. Water is used as the medium, and a voltage of 100kV is applied. The electrode spacing is controlled at 5mm, the discharge frequency at 2Hz, and the number of pulses at 300. Simultaneously, ultraviolet light is applied with a main wavelength of 200nm and a light intensity of 12mW / cm². 2 .

[0088] Example 4

[0089] This embodiment provides a method for recycling waste lithium battery cathode materials using high-voltage pulses. The only difference from Embodiment 1 is that the operating parameters in step (2) are different, as follows:

[0090] The crushed material from step (1) is transferred to a high-pressure pulse crusher. Water is used as the medium, and a voltage of 180kV is applied. The electrode spacing is controlled at 10mm, the discharge frequency at 5Hz, and the number of pulses at 400. Simultaneously, ultraviolet light is applied with a main wavelength of 380nm and a light intensity of 36mW / cm². 2 .

[0091] Example 5

[0092] The only difference from Example 1 is that the voltage applied in step (2) is 80kV.

[0093] Example 6

[0094] The only difference from Example 1 is that the voltage applied in step (2) is 250kV.

[0095] Example 7

[0096] The only difference from Example 1 is that the frequency applied in step (2) is 8 Hz.

[0097] Example 8

[0098] The only difference from Example 1 is that the electrode spacing in step (2) is 20 mm.

[0099] Example 9

[0100] The only difference from Example 1 is that the number of pulses in step (2) is 200.

[0101] Example 10

[0102] The only difference from Example 1 is that the number of pulses in step (2) is 500.

[0103] Comparative Example 1

[0104] The only difference from Example 1 is that: in step (2) high-pressure pulse breaking process, no ultraviolet light irradiation is used.

[0105] Comparative Example 2

[0106] The only difference from Example 1 is that the high-pressure pulse crushing device in step (2) is replaced with a twin-shaft crusher, so that the particle size after crushing in step (2) is consistent with that in Example 1.

[0107] Test Example 1

[0108] The recovery rate and aluminum impurity content of the cathode material powder were obtained from the test examples and comparative examples, and the results are shown in Table 1.

[0109] Test methods: (1) The formula for calculating the recovery rate is: positive electrode material recovery rate = positive electrode material recovery amount ÷ total positive electrode material waste amount × 100%; (2) The aluminum content of impurities is tested by ICP.

[0110] Table 1. Results of Recovery Rate and Impurity Content Tests

[0111]

[0112]

[0113] As can be seen from Table 1, the content of aluminum impurities in Comparative Example 1 is very high, and the recovery rate is also significantly reduced; the recovery rate of Comparative Example 2 is significantly lower than that of other examples. In Examples 5-10, the operating parameters during the crushing process in step (2) exceed the parameter range defined in this disclosure, which will lead to a decrease in recovery rate or a significant increase in impurity content.

[0114] Industrial applicability

[0115] This disclosure employs a high-voltage pulse combined with ultraviolet irradiation to crush waste positive electrode sheets, effectively separating the titanium dioxide-coated positive electrode material from the positive electrode current collector (such as aluminum foil), significantly improving the separation rate, and resulting in very low aluminum content in the separated positive electrode material. In practical operation, the recycling process is simple and easy to implement, and the crushing process is convenient, demonstrating excellent industrial applicability.

Claims

1. A method for recycling waste lithium battery cathode materials via high-voltage pulse, characterized in that, include: Waste positive electrode sheets are crushed under the combined action of high voltage electric pulse and ultraviolet light; The cathode material in the waste cathode sheet includes a cathode material matrix and a coating layer covering the cathode material matrix, wherein the coating layer contains titanium dioxide. The applied high-voltage electric pulse has a voltage of 100kV-180kV, a control electrode spacing of 5mm-10mm, and a pulse count of 300-400. The applied ultraviolet light has a dominant wavelength of 200nm-380nm and an irradiance of 12mW / cm². 2 ~36mW / cm 2 .

2. The method according to claim 1, characterized in that, The applied high-voltage electrical pulse has a voltage of 120kV-150kV.

3. The method according to claim 1, characterized in that, The waste positive electrode sheet is first crushed once, and then placed in a high-voltage pulse crusher for secondary crushing. Ultraviolet light is applied during the secondary crushing process.

4. The method according to claim 3, characterized in that, During the secondary crushing process, the electrode spacing is controlled to be 6mm-10mm and the number of pulses is 300-350.

5. The method according to claim 3, characterized in that, During the secondary crushing process, water is used as the medium, and the discharge frequency is controlled to be 2Hz-5Hz.

6. The method according to claim 3, characterized in that, The applied ultraviolet light has a dominant wavelength of 350nm-380nm and an irradiance of 15mW / cm². 2 ~25mW / cm 2 .

7. The method according to claim 3, characterized in that, The first crushing involves crushing the waste positive electrode sheet to 10mm-50mm.

8. The method according to claim 1, characterized in that, The cathode material matrix is ​​selected from at least one of lithium iron phosphate, lithium manganese iron phosphate, lithium nickel cobalt manganese oxide, and lithium cobalt oxide.

9. The method according to claim 1, characterized in that, The positive current collector in the waste positive electrode sheet is aluminum foil, and the waste positive electrode sheet contains at least one of polyvinylidene fluoride, styrene-butadiene latex and polytetrafluoroethylene.

10. The method according to claim 1, characterized in that, Also includes: After the waste positive electrode sheet is crushed under high voltage pulse and ultraviolet light, the crushed material is post-processed to obtain positive electrode material powder.

11. The method according to claim 10, characterized in that, The post-processing includes drying and sorting the crushed material sequentially to remove fragments from the collector.

12. The method according to claim 11, characterized in that During the drying process, the drying temperature is controlled at 50℃-80℃, and the drying time is 6h-24h.

13. The method according to claim 11, characterized in that, The sorting process employs a combination of air separation and screening.

14. The method according to claim 13, characterized in that, Use a 50-100 mesh sieve for screening.

15. The method according to claim 11, characterized in that, Also includes: The undersize powder obtained from the sorting is sieved through a 300-500 mesh vibrating screen to obtain the positive electrode material powder.

16. The method according to claim 10, characterized in that, Also includes: The obtained cathode material powder is mixed with a lithium source and sintered to obtain a recycled cathode material.

17. The method according to claim 16, characterized in that, In the process of preparing the regenerated cathode material, a first sintering is carried out at 450℃-650℃, and then the temperature is increased to 700℃-1000℃ for a second sintering.

18. The method according to claim 17, characterized in that, The sintering time for a single sintering is 1-6 hours.

19. The method according to claim 17, characterized in that, The temperature is increased to the sintering temperature of the first sintering at a heating rate of 2℃ / min-10℃ / min.

20. The method according to claim 17, characterized in that, The sintering time for the second sintering is 6-12 hours.

21. The method according to claim 16, characterized in that, By controlling the amount of lithium source used, the molar ratio of lithium content to the total amount of other metal elements in the mixture is made to be 1.01-1.03:

1.

22. The method according to claim 16, characterized in that, The lithium source is selected from at least one of lithium hydroxide and lithium carbonate.

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