Method for recycling positive electrode material of waste lithium battery by means of high-voltage pulses

Abstract

A method for recycling a positive electrode material of a waste lithium battery by means of high-voltage pulses. The method comprises: crushing a waste positive electrode sheet under the synergistic effect of high-voltage pulses and ultraviolet irradiation, wherein a positive electrode material in the waste positive electrode sheet comprises a positive electrode material matrix and a coating layer that is coated on the positive electrode material matrix, and the coating layer comprises titanium dioxide. As the waste positive electrode sheet is crushed by means of the synergism of high-voltage pulses and ultraviolet irradiation, the positive electrode material coated with titanium dioxide can be effectively stripped from a positive electrode current collector, and the stripping rate is significantly improved; and the content of aluminum in the stripped positive electrode material is very low.

Description

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

[0001] The present disclosure belongs to the technical field of waste battery recycling, and in particular, relates to a method for recycling positive electrode materials of waste lithium batteries through high voltage pulses. Background Art

[0002] With the rapid development of new energy vehicles, domestic power battery shipments continue to increase. Due to the limited battery life, a large number of waste lithium-ion batteries are generated. Scrapped 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 focus on hydrometallurgy, pyrometallurgy, and the combined use of hydrometallurgy and pyrometallurgy. Hydrometallurgy primarily uses acid leaching to dissolve valuable metals, followed by extraction or precipitation to remove the valuable metal elements. This method requires the use of large amounts of acid leaching reagents, is costly, and can easily cause environmental pollution. Pyrometallurgy, on the other hand, removes organic matter and binders through high-temperature calcination, and then obtains the product through screening, magnetic separation, and other methods. However, this method is prone to the contamination of metal impurities such as copper and aluminum and has high energy consumption.

[0003] Many discarded lithium-ion batteries have their cathode materials modified by coating, a process that can improve the electrochemical performance of cathode materials. Titanium dioxide, as an excellent coating material with strong adhesion and stable chemical properties, is commonly used in coating and modification of cathode materials, resulting in even better electrochemical performance.

[0004] However, if titanium dioxide-coated materials are recycled using hydrometallurgical or pyrometallurgical methods, the coating will be converted into impurities in the valuable metals, making the recovered materials difficult to reuse. Therefore, it is urgent to develop a method for directly recovering the positive electrode powder of titanium dioxide-coated positive electrode materials.

[0005] In view of this, the present disclosure is proposed.

[0006] Summary of the Invention

[0007] The purpose of the present disclosure includes providing a method for recycling positive electrode materials of waste lithium batteries through high-voltage pulses, aiming to effectively separate the positive electrode materials while ensuring the recovery rate and controlling the impurity aluminum content.

[0008] In order to achieve the above-mentioned purpose of the present disclosure, the following technical solutions can be adopted:

[0009] The solution provided by the present disclosure includes a method for recycling waste lithium battery positive electrode materials through high voltage pulses, comprising: crushing the waste positive electrode sheets under the synergistic effect of high voltage electric pulses and ultraviolet light;

[0010] The positive electrode material in the waste positive electrode sheet includes a positive electrode material matrix and a coating layer coated on the positive electrode material matrix, and the coating layer contains titanium dioxide.

[0011] In some embodiments of the present disclosure, the voltage of the applied high voltage electric pulse is 100 kV-180 kV.

[0012] In some embodiments of the present disclosure, the voltage of the applied high voltage electric pulse is 120 kV-150 kV.

[0013] In some embodiments of the present disclosure, the waste positive electrode sheets are first crushed once and then placed in a high-voltage pulse crusher for secondary crushing, and ultraviolet light irradiation is applied during the secondary crushing process.

[0014] In some embodiments of the present disclosure, during the secondary crushing process, the electrode spacing is controlled to be 5 mm-10 mm, and the number of pulses is 300-400.

[0015] In some embodiments of the present disclosure, during the secondary crushing process, the electrode spacing is controlled to be 6 mm-10 mm, and the number of pulses is 300-350.

[0016] In some embodiments of the present disclosure, during the secondary crushing process, water is used as the medium and the discharge frequency is controlled to be 2 Hz-5 Hz.

[0017] In some embodiments of the present disclosure, the applied ultraviolet light has a main wavelength of 200 nm to 380 nm and an illumination intensity of 12 mW / cm 2 ~36mW / cm 2 .

[0018] In some embodiments of the present disclosure, the applied ultraviolet light has a main wavelength of 350nm-380nm and a light intensity of 15mW / cm 2 ~25mW / cm 2 .

[0019] In some embodiments of the present disclosure, the primary crushing is to crush the waste positive electrode sheets into 10 mm-50 mm.

[0020] In some embodiments of the present disclosure, the positive electrode 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.

[0021] In some embodiments of the present disclosure, the positive electrode 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.

[0022] In some embodiments of the present disclosure, the method further includes: crushing the waste positive electrode sheets under conditions of high-voltage electric pulses and ultraviolet light, and then post-processing the crushed materials to obtain positive electrode material powder.

[0023] In some embodiments of the present disclosure, post-processing includes drying and sorting the crushed material in sequence to remove current collector fragments.

[0024] In some embodiments of the present disclosure, during the drying process, the drying temperature is controlled to be 50° C.-80° C., and the drying time is controlled to be 6 h-24 h.

[0025] In some embodiments of the present disclosure, sorting is performed by combining air separation and screening.

[0026] In some embodiments of the present disclosure, screening is performed using a 50-100 mesh sieve.

[0027] In some embodiments of the present disclosure, the process further includes: screening the undersize powder obtained by sorting through a 300-500 mesh vibrating sieve to obtain a positive electrode material powder.

[0028] In some embodiments of the present disclosure, the method further includes: mixing the obtained positive electrode material powder with a lithium source and sintering the mixture to obtain a regenerated positive electrode material.

[0029] In some embodiments of the present disclosure, during the preparation of the regenerated positive electrode material, a primary sintering is performed at 450° C.-650° C., and then the temperature is raised to 700° C.-1000° C. for a secondary sintering.

[0030] In some embodiments of the present disclosure, the sintering time of the first sintering is 1 hour to 6 hours.

[0031] In some embodiments of the present disclosure, the temperature is increased to the sintering temperature for the primary sintering at a heating rate of 2° C. / min-10° C. / min.

[0032] In some embodiments of the present disclosure, the sintering time of the secondary sintering is 6 hours to 12 hours.

[0033] In some embodiments of the present disclosure, by controlling the amount of lithium source, the molar ratio of lithium content to the total amount of other metal elements in the mixed material is 1.01-1.03:1.

[0034] In some embodiments of the present disclosure, the lithium source is selected from at least one of lithium hydroxide and lithium carbonate.

[0035] The waste positive electrode sheets are broken up by combining high-voltage electric pulses with ultraviolet light, which can effectively separate the titanium dioxide-coated positive electrode material from the positive electrode current collector (such as aluminum foil), and the stripping rate is significantly improved. The aluminum content in the stripped positive electrode material is very low.

[0036] It should be noted that the use of high-voltage electric pulses in conjunction with ultraviolet light for fragmentation can not only ensure the stripping rate of the positive electrode material but also reduce the aluminum content in the positive electrode material. This may be based on the following principles:

[0037] The electrons generated by titanium dioxide under the action of ultraviolet light obtain additional energy under the action of an external electric field, allowing them to penetrate the potential barrier. The avalanche current generated by the carriers produces a large number of conductive channels at the interface, and there is a large amount of plasma in the conductive channels. During the expansion of the plasma, the conductive channels are distributed in a dendritic manner on the interface, thereby dissociating the interface between the positive electrode material and the positive electrode collector (such as aluminum foil), and then obtaining a broken product containing the positive electrode collector and the positive electrode powder.

[0038] In addition, titanium dioxide will produce a large number of holes under ultraviolet light. Holes have a strong oxidizing effect and can oxidize the binder (such as polyvinylidene fluoride PVDF) to a certain extent and break the bonds. However, since PVDF is relatively stable, the efficiency of PVDF oxidation by holes alone is low. The external electric field of the high-voltage pulse promotes the movement of electrons, which not only allows more electrons to participate in the interfacial dissociation between the positive electrode material and the positive electrode current collector (such as aluminum foil), but also allows more electrons to migrate instead of recombining with holes, thereby promoting the generation of a large number of holes and promoting the oxidation and breaking of PVDF. Therefore, under the synergistic effect of ultraviolet light and high-voltage pulses, the stripping rate between the titanium dioxide-coated positive electrode material and the positive electrode current collector (such as aluminum foil) is improved, and the aluminum impurity content of the stripped positive electrode material is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0040] FIG1 is a flow chart of recycling waste lithium-ion battery positive electrode materials provided by the present disclosure;

[0041] FIG2 is a physical photo of the regenerated positive electrode material of Example 1. DETAILED DESCRIPTION

[0042] The embodiments of the present disclosure will be described in detail below with reference to the examples. However, those skilled in the art will appreciate that the following examples are intended only to illustrate the present disclosure and should not be construed as limiting the scope of the present disclosure. Where specific conditions are not specified in the examples, the experiments were performed under conventional conditions or the conditions recommended by the manufacturer. Where the manufacturer of the reagents or instruments is not specified, all are commercially available conventional products.

[0043] The endpoints of the ranges and any values ​​disclosed in this disclosure are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed herein.

[0044] The present disclosure provides a method for recycling cathode materials of waste lithium batteries by high voltage pulses, as shown in FIG1 , including the following steps:

[0045] S1. Primary crushing (coarse crushing)

[0046] First, the spent positive electrode sheets undergo a primary crushing process, producing smaller fragments through coarse crushing. This allows for better separation of the positive electrode material and current collector during the secondary crushing process. This primary crushing step is optional and unnecessary for smaller positive electrode sheets. For larger sheets, increasing the secondary crushing time can also improve separation.

[0047] Specifically, spent positive electrode sheets are obtained by discharging and disassembling spent lithium-ion batteries to separate the spent positive electrode sheets. The positive electrode material in the spent positive electrode sheets includes a positive electrode material matrix and a coating layer coated on the positive electrode material matrix. The coating layer contains titanium dioxide. The method provided in this disclosure is primarily aimed at recovering titanium dioxide-coated positive electrode materials.

[0048] The positive electrode 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, and 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.

[0049] Furthermore, the cathode 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 can better bond the positive electrode active coating to the positive electrode current collector.

[0050] In some embodiments, the primary crushing is to crush the waste positive electrode sheets into 10mm-50mm, such as 10mm, 20mm, 30mm, 40mm, 50mm, etc., and the crushing can be performed by an existing crusher, which can be a jaw crusher, an impact crusher, a shear crusher, etc.

[0051] S2, secondary crushing (high-voltage pulse crushing combined with ultraviolet light)

[0052] The waste cathode sheets undergo secondary crushing under the synergistic effect of high-voltage electric pulses and ultraviolet light. In actual operation, the material can be placed in a high-voltage pulse crusher for secondary crushing, and ultraviolet light is applied during the secondary crushing process. The combination of high-voltage electric pulses and ultraviolet light can both ensure the stripping rate of the cathode material and reduce the aluminum content in the cathode material.

[0053] Specifically, a high-voltage pulse disruptor is an existing disruptor. Its disruptor mechanism is as follows: Under the action of a high-voltage pulse discharge, the different dielectric constants of different components within a material increase the field strength at the interface between the different materials, causing electrical breakdown and the formation of a conductive channel. The large amount of high-temperature, high-pressure plasma generated in the conductive channel expands the channel, causing the different materials to dissociate along the interface.

[0054] In the disclosed embodiment, the working principle of high-voltage pulse fragmentation and ultraviolet light irradiation is utilized: the electrons generated by titanium dioxide under the action of ultraviolet light obtain additional energy under the action of an external electric field, which allows them to penetrate the potential barrier, and the avalanche current generated by the carriers generates a large number of conductive channels at the interface, and there is a large amount of plasma in the conductive channel. During the plasma expansion process, the conductive channel is distributed in a dendritic manner on the interface, thereby dissociating the interface between the positive electrode material and the positive electrode collector (such as aluminum foil), and then obtaining a broken product containing the positive electrode collector (such as aluminum foil) and the positive electrode powder. In addition, titanium dioxide will produce a large number of holes under ultraviolet light irradiation. The holes have a strong oxidizing effect and can oxidize the binder (such as polyvinylidene fluoride PVDF) to a certain extent. Breaking bonds, but because PVDF is relatively stable, the efficiency of PVDF oxidation by holes alone is low. The external electric field of the high-voltage pulse promotes the movement of electrons, not only allowing more electrons to participate in the interfacial dissociation of the positive electrode material and the positive electrode collector (such as aluminum foil), but also allowing more electrons to migrate instead of recombining with holes, thereby promoting the generation of a large number of holes and promoting the oxidation and breaking bonds of PVDF. Therefore, under the synergistic effect of ultraviolet light and high-voltage pulses, the stripping rate between the titanium dioxide-coated positive electrode material and the positive electrode current collector is improved, and the aluminum impurity content of the stripped positive electrode material is low.

[0055] In some embodiments, the voltage of the applied high-voltage electric pulse is 100 kV-180 kV, preferably 120 kV-150 kV. If the applied voltage is too low, the stripping effect will be affected, while if the applied voltage is too high, the stability of the device will be poor. Specifically, the voltage of the applied high-voltage electric pulse can be 100 kV, 110 kV, 120 kV, 130 kV, 140 kV, 150 kV, 160 kV, 170 kV, 180 kV, etc.

[0056] Furthermore, during the secondary crushing process, the electrode spacing is controlled to be 5mm-10mm, and the number of pulses is 300-400; preferably, the electrode spacing is controlled to be 6mm-10mm, and the number of pulses is 300-350. Controlling the electrode spacing within this range results in better stripping results. The number of pulses refers to the number of repeated discharges to the waste electrode. Controlling the number of pulses within this range results in better stripping results. If the number of pulses is too small, the stripping effect will be reduced. If the number of pulses is too large, the stripping effect will not be further improved and the cost will be increased.

[0057] Specifically, during the secondary crushing process, the control electrode spacing can be 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, etc., and the number of pulses can be 300, 320, 350, 370, 400, etc.

[0058] In some embodiments, during the secondary crushing process, water is used as the discharge carrier. Under the action of a high electric field, a plasma discharge channel is generated within the aqueous medium, thereby completing the discharge circuit and releasing energy in a short period of time. The shock wave pressure generated by the expansion of the discharge plasma breaks down the gap between the electrodes, causing the solid to break. During the secondary crushing process, the discharge frequency is controlled to be between 2Hz and 5Hz, such as 2Hz, 3Hz, 4Hz, and 5Hz. Excessively high discharge frequencies can affect the stability of the device.

[0059] In some embodiments, the applied ultraviolet light has a dominant wavelength of 200 nm to 380 nm and an intensity of 12 mW / cm 2 ~36mW / cm 2 Preferably, the applied ultraviolet light has a main wavelength of 350nm-380nm and a light intensity of 15mW / cm 2 ~25mW / cm 2 . UV light is applied to the high-voltage pulse crusher using a UV lamp, and the main wavelength and light intensity are preferably controlled within the above range to further enhance the peeling effect.

[0060] Specifically, the main wavelength of the applied ultraviolet light can be 200nm, 250nm, 300nm, 350nm, 380nm, etc., and the light intensity can be 12mW / cm 2 , 15mW / cm2 , 20mW / cm 2 , 25mW / cm 2 、30mW / cm 2 、36mW / cm 2 wait.

[0061] S3, post-processing

[0062] After the waste positive electrode sheets are crushed under the conditions of high-voltage electric pulses and ultraviolet light, the crushed materials are post-processed to obtain positive electrode material powder, so that the positive electrode material can be reused.

[0063] In some embodiments, post-processing includes drying and sorting the crushed material to remove current collector fragments. Drying can remove moisture from the material surface. Since the positive electrode material is mainly in powder form, sorting can separate the current collector fragments from the positive electrode material.

[0064] In some embodiments, during the drying process, the drying temperature is controlled to be 50° C.-80° C., and the drying time is 6 hours-24 hours. Specifically, the drying temperature can be 50° C., 60° C., 70° C., 80° C., etc., and the drying time can be 6 hours, 10 hours, 15 hours, 20 hours, 24 hours, etc.

[0065] In some embodiments, the separation is carried out by combining air separation and screening, and air separation can be performed first and then screening, or screening can be performed first and then air separation. Air separation is performed by using an air separator, and screening is performed by using a screen.

[0066] In some embodiments, a 50-100 mesh screen is used for screening to remove large particles of current collector debris. The mesh size of the screen can be 50 mesh, 60 mesh, 70 mesh, 80 mesh, 90 mesh, 100 mesh, etc.

[0067] In some embodiments, after the separation is completed, the process further includes: screening the screened powder through a 300-500 mesh vibrating screen to obtain a cathode material powder with a smaller particle size for preparing a regenerated cathode material. The mesh size of the vibrating screen can be 300 mesh, 400 mesh, 500 mesh, etc.

[0068] S4, lithium regeneration

[0069] The obtained positive electrode material powder is mixed with a lithium source and sintered to obtain a regenerated positive electrode material. The regenerated positive electrode material still has good electrochemical properties, thereby improving the utilization value of waste positive electrode sheets.

[0070] In some embodiments, during the preparation of the recycled positive electrode material, a primary sintering process is performed at 450°C-650°C for 1-6 hours, followed by a secondary sintering process at 700°C-1000°C for 6-12 hours. This double sintering process can further improve the electrochemical performance of the recycled positive electrode material.

[0071] Specifically, the temperature of the first sintering can be 450℃, 500℃, 550℃, 600℃, 650℃, etc., and the first sintering time can be 1h, 2h, 3h, 4h, 5h, 6h, etc.; the temperature of the second sintering can be 700℃, 800℃, 900℃, 1000℃, etc., and the second sintering time can be 6h, 8h, 10h, 12h, etc.

[0072] In some embodiments, the temperature is raised to the sintering temperature for the primary sintering at a heating rate of 2°C / min-10°C / min, and the temperature is raised evenly to prevent the heating rate from being too fast. Specifically, the heating rate can be 2°C / min, 5°C / min, 7°C / min, 10°C / min, etc.

[0073] In some embodiments, the amount of lithium source is controlled so that the molar ratio of lithium to the total amount of other valuable metal elements in the mixture to be sintered is 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 may be any one or more of the above.

[0074] The waste positive electrode sheets are broken up by combining high-voltage electric pulses with ultraviolet light, which can effectively separate the titanium dioxide-coated positive electrode material from the positive electrode current collector (such as aluminum foil), and the stripping rate is significantly improved. The aluminum content in the stripped positive electrode material is very low.

[0075] The features and performance of the present disclosure are further described in detail below with reference to the embodiments.

[0076] It should be noted that the types of waste positive electrode sheets used in the following embodiments or comparative examples are the same, 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 sheet also contains a binder PVDF, the content of which is about 1% to 10% of the mass of the positive electrode material.

[0077] Example 1

[0078] This embodiment provides a method for recycling waste lithium battery positive electrode materials by high voltage pulse, comprising the following steps:

[0079] (1) Use a double-shaft crusher to crush the waste positive electrode sheets into a median particle size of about 30 mm.

[0080] (2) The crushed material in step (1) was transferred to a high-voltage pulse crusher, with water as the medium, a voltage of 130 kV was applied, the electrode spacing was controlled to be 8 mm, the discharge frequency was 4 Hz, the number of pulses was 300, and ultraviolet light was applied at the same time, the main wavelength of the ultraviolet lamp was 380 nm, and the light intensity was 20 mW / cm 2 .

[0081] (3) The crushed material in step (2) was dried at 60°C for 12 hours, and then sorted through a 50-mesh sieve to remove large particles of collector fragments. The screened powder obtained by sorting was then sieved through a 300-mesh vibrating sieve to obtain a positive electrode material powder, as shown in FIG2 .

[0082] Example 2

[0083] This embodiment provides a method for recycling waste lithium battery positive electrode materials by high voltage pulse. Step (4) is added based on steps (1) to (3) of embodiment 1. The specific steps of step (4) are as follows:

[0084] The element content in the positive electrode material was measured by ICP, and the obtained positive electrode material powder was mixed with lithium hydroxide, and the lithium source was supplemented so that the molar ratio of lithium ions in the mixture to the total molar ratio of other valuable metals in the positive electrode material powder was 1.02:1. After mixing evenly, the mixture was heated to 500°C at a heating rate of 5°C / min and sintered for 4 hours, and then heated to 800°C and sintered for 10 hours to obtain a regenerated positive electrode material.

[0085] The recycled positive electrode material was mixed with conductive acetylene black, PVDF, and NMP in a mass ratio of 90:5:5:30 to create a positive electrode slurry. The slurry was coated onto aluminum foil to a thickness of approximately 50 μm and dried to produce a positive electrode sheet. Coin-type batteries were prepared in an argon glove box using the 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. After 100 cycles, the discharge capacity remained at 159.73 mAh / g, with a capacity retention rate of 94.61%.

[0086] Example 3

[0087] This embodiment provides a method for recycling waste lithium battery positive electrode materials by high voltage pulse. The difference from Example 1 is that the operating parameters of step (2) are different, as follows:

[0088] The crushed material in step (1) was transferred to a high-voltage pulse crusher, with water as the medium, a voltage of 100 kV was applied, the electrode spacing was controlled to be 5 mm, the discharge frequency was 2 Hz, the number of pulses was 300, and ultraviolet light was applied at the same time, the main wavelength of the ultraviolet lamp was 200 nm, and the light intensity was 12 mW / cm 2 .

[0089] Example 4

[0090] This embodiment provides a method for recycling waste lithium battery positive electrode materials by high voltage pulse. The difference from Example 1 is that the operating parameters of step (2) are different, as follows:

[0091] The crushed material in step (1) was transferred to a high-voltage pulse crusher, with water as the medium, a voltage of 180 kV was applied, the electrode spacing was controlled to be 10 mm, the discharge frequency was 5 Hz, the number of pulses was 400, and ultraviolet light was applied at the same time, the main wavelength of the ultraviolet lamp was 380 nm, and the light intensity was 36 mW / cm 2 .

[0092] Example 5

[0093] The only difference from Example 1 is that the voltage applied in step (2) is 80 kV.

[0094] Example 6

[0095] The only difference from Example 1 is that the voltage applied in step (2) is 250 kV.

[0096] Example 7

[0097] The only difference from Example 1 is that the frequency applied in step (2) is 8 Hz.

[0098] Example 8

[0099] The only difference from Example 1 is that the electrode spacing in step (2) is 20 mm.

[0100] Example 9

[0101] The only difference from Example 1 is that the number of pulses in step (2) is 200.

[0102] Example 10

[0103] The only difference from Example 1 is that the number of pulses in step (2) is 500.

[0104] Comparative Example 1

[0105] The only difference from Example 1 is that in step (2) the high-voltage pulse fragmentation process, no auxiliary ultraviolet light irradiation is performed.

[0106] Comparative Example 2

[0107] The only difference from Example 1 is that the high-pressure pulse crushing device in step (2) is replaced by a double-shaft crusher, so that the particle size after crushing in step (2) remains consistent with that in Example 1.

[0108] Test Example 1

[0109] The recovery rate and impurity aluminum content of the positive electrode material powder were obtained by testing the examples and comparative examples. The results are shown in Table 1.

[0110] Test method: (1) The recovery rate is calculated as follows: positive electrode material recovery rate = positive electrode material recovery amount / total positive electrode material waste amount × 100%; (2) The impurity aluminum content is tested using ICP.

[0111] Table 1 Recovery rate and impurity content test results

[0112] As can be seen from Table 1, the content of impurity aluminum in Comparative Example 1 is very high, and the recovery rate is significantly reduced; the recovery rate of Comparative Example 2 is significantly lower than that of the other examples. In Examples 5-10, the operating parameters during the crushing process in step (2) exceed the parameter ranges specified in this disclosure, resulting in a decrease in recovery rate or a significant increase in impurity content. Industrial Applicability

[0113] This method uses high-voltage electric pulses in conjunction with ultraviolet light to break up used positive electrode sheets. This method effectively separates 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 a very low aluminum content in the separated positive electrode material. In practice, the recycling process is simple and easy, and the breaking process is convenient, demonstrating excellent industrial applicability.

Claims

1. A method for recycling waste lithium battery positive electrode materials by high voltage pulse, characterized in that: include: The waste positive electrode sheets are broken down under the synergistic effect of high voltage electric pulses and ultraviolet light; The positive electrode material in the waste positive electrode sheet comprises a positive electrode material matrix and a coating layer coated on the positive electrode material matrix, and the coating layer contains titanium dioxide.

2. The method according to claim 1, characterized in that The voltage of the applied high voltage electric pulse is 100 kV-180 kV.

3. The method according to claim 2, characterized in that The voltage of the applied high voltage electric pulse is 120 kV-150 kV.

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

5. The method according to claim 4, characterized in that In the secondary crushing process, the electrode spacing is controlled to be 5 mm-10 mm, and the number of pulses is 300-400.

6. The method according to claim 5, characterized in that In the secondary crushing process, the electrode spacing is controlled to be 6 mm-10 mm, and the number of pulses is 300-350.

7. The method according to any one of claims 4 to 6, characterized in that: In the secondary crushing process, water is used as the medium and the discharge frequency is controlled to be 2 Hz-5 Hz.

8. The method according to any one of claims 4 to 7, characterized in that: The main wavelength of the applied UV light is 200nm-380nm, and the light intensity is 12mW / cm 2 ~36mW / cm 2 .

9. The method according to claim 8, characterized in that The main wavelength of the applied UV light is 350nm-380nm, and the light intensity is 15mW / cm 2 ~25mW / cm 2 .

10. The method according to any one of claims 4 to 9, characterized in that: The primary crushing is to crush the waste positive electrode sheets into pieces of 10mm-50mm.

11. The method according to any one of claims 1 to 10, characterized in that The positive electrode material matrix is ​​selected from at least one of lithium iron phosphate, lithium iron manganese phosphate, lithium nickel cobalt manganese oxide and lithium cobalt oxide.

12. The method according to any one of claims 1 to 11, characterized in that The positive electrode 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.

13. The method according to any one of claims 1 to 12, characterized in that Also includes: After the waste positive electrode sheets are crushed under the conditions of high voltage electric pulses and ultraviolet light, the crushed materials are post-processed to obtain positive electrode material powder.

14. The method according to claim 13, characterized in that The post-processing includes drying and sorting the crushed materials in sequence to remove the collector fragments.

15. The method according to claim 14, characterized in that During the drying process, the drying temperature is controlled to be 50° C.-80° C., and the drying time is controlled to be 6 h-24 h.

16. The method according to claim 14 or 15, characterized in that The sorting is carried out by combining wind selection and screening.

17. The method according to claim 16, characterized in that Use a 50-100 mesh sieve for screening.

18. The method according to any one of claims 14 to 17, characterized in that: Also includes: The screened powder obtained by sorting is sieved through a 300-mesh to 500-mesh vibrating screen to obtain the positive electrode material powder.

19. The method according to any one of claims 13 to 18, characterized in that Also includes: The obtained positive electrode material powder is mixed with a lithium source and sintered to obtain a regenerated positive electrode material.

20. The method according to claim 19, characterized in that In the process of preparing the regenerated positive electrode material, a primary sintering is first performed at 450° C.-650° C., and then the temperature is raised to 700° C.-1000° C. for a secondary sintering.

21. The method according to claim 20, characterized in that The sintering time for one sintering is 1h-6h.

22. The method according to claim 20 or 21, characterized in that The temperature is increased to the sintering temperature of the primary sintering at a heating rate of 2° C. / min-10° C. / min.

23. The method according to any one of claims 20 to 22, characterized in that The sintering time of the secondary sintering is 6h-12h.

24. The method according to any one of claims 19 to 23, characterized in that By controlling the amount of the lithium source, the molar ratio of the lithium content in the mixed material to the total amount of other metal elements is 1.01-1.03:

1.

25. The method according to any one of claims 19 to 24, characterized in that The lithium source is selected from at least one of lithium hydroxide and lithium carbonate.

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