Recycling method and recycling equipment of positive electrode material

Abstract

The embodiment of the invention provides a recovery method and recovery equipment of a positive electrode material. The recovery method of the positive electrode material comprises the following steps: S1, carrying out catalytic oxidation treatment on a positive electrode plate to obtain intermediate positive electrode material powder and a positive electrode current collector; s2, performing controlled electrooxidation treatment on the intermediate positive electrode material powder to obtain positive electrode material powder; the positive electrode material powder comprises LixNiyCozMnaO2, 0 < x < = 1.05, 0 < = y < = 0.9, 0 < z < = 0.4, and 0 < = a < = 0.5. The recovery method can realize separation and purification of the positive electrode material and the positive electrode current collector (metal foil) in a high-efficiency and environment-friendly manner.

Description

Technical Field

[0001] This application relates to the field of electrochemical technology, and in particular to a method and equipment for recycling cathode materials. Background Technology

[0002] The recycling and processing of spent lithium cobalt oxide batteries is a core aspect of the resource utilization of lithium-ion batteries. Lithium cobalt oxide batteries are widely used in smartphones, laptops, and electric vehicles due to their high energy density and cycle stability. However, as the battery's lifespan ends, the recycling value of its cathode material (lithium cobalt oxide) and metal foil (aluminum foil) becomes significant. Cobalt, as a strategic metal resource, has its recycling rate directly impacting the sustainable development of the new energy industry; while high-value recycling of aluminum foil can reduce resource waste. Furthermore, residual electrolytes, binders, and other organic matter in the batteries, if not properly treated, can pollute the environment. Therefore, developing efficient and environmentally friendly recycling processes to separate and purify cathode materials and metal foil is an urgent need in the current battery recycling field. Summary of the Invention

[0003] This application provides a method and equipment for recycling cathode materials, which can efficiently and environmentally separate and purify cathode materials from cathode current collectors (metal foil).

[0004] In a first aspect, embodiments of this application provide a method for recycling a positive electrode material, comprising:

[0005] S1: Catalytic oxidation of the positive electrode sheet to obtain intermediate positive electrode material powder and positive electrode current collector;

[0006] S2: Perform controlled-electro-oxidation treatment on the intermediate cathode material powder to obtain cathode material powder;

[0007] The cathode material powder includes Li x Ni y Co z Mn a O2, 0<x≤1.05, 0≤y≤0.9, 0<z≤0.4, 0≤a≤0.5.

[0008] The recycling method described above further includes washing the positive electrode sheet before step S1.

[0009] The recycling method described above, wherein 1 ≤ x ≤ 1.05; and / or, the cathode material powder comprises lithium cobalt oxide.

[0010] In the recovery method described above, the catalyst in the catalytic oxidation treatment is a cobalt-based catalyst, and the concentration of the cobalt-based catalyst is 50-100 ppm; and / or,

[0011] The flow rate of the oxidant is 2-10 g / h.

[0012] In the recovery method described above, the catalytic oxidation treatment lasts for 1-5 hours and the pH is 6.5-7.5.

[0013] In the recovery method described above, the controlled-electro-oxidation treatment involves an oxygen flow rate of 0.05-0.1 g / h, a reaction potential of <0.35 V, a time of 10-30 min, and a pH of 5-6.

[0014] The recycling method described above further includes, after S2:

[0015] The cathode material powder is mixed with raw materials including at least a lithium source and then calcined to obtain a recycled cathode material.

[0016] In the recycling method described above, the raw material further includes a coating source, wherein the coating element in the coating source includes at least one of Mg, Ti, and Zr.

[0017] In the recycling method described above, the roasting process is carried out at a temperature of 700-1000℃ for a time of 5-22 hours.

[0018] Secondly, embodiments of this application provide a recovery system for implementing the cathode material as described above, comprising a catalytic oxidation unit and a controlled-electro-oxidation unit;

[0019] The catalytic oxidation unit has a positive electrode current collector outlet, and the intermediate positive electrode powder outlet of the catalytic oxidation unit is connected to the inlet of the electro-controlled oxidation unit.

[0020] The cathode material recycling method and recycling apparatus provided in this application include sequentially performing catalytic oxidation treatment and controlled-electro-oxidation treatment on the cathode sheet to obtain cathode material powder. This recycling method can efficiently and environmentally separate the cathode material from the cathode current collector (metal foil), and has excellent economic benefits. Attached Figure Description

[0021] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0022] Figure 1 This is a process flow diagram of the recovery process of the cathode material in some embodiments of the present invention. Detailed Implementation

[0023] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0024] Existing methods (such as pyrometallurgical and wet methods) struggle to achieve efficient separation of the cathode material and the cathode current collector. Residual binders or organic matter lead to incomplete separation, resulting in low recovery rates and poor quality of the cathode current collector. Mechanical crushing or manual stripping introduces impurities such as aluminum into the cathode active material powder, affecting its purity. This application addresses these technical challenges by employing a wet selective catalytic oxidation process to achieve efficient separation of the cathode material and the cathode current collector at room temperature and pressure. Combined with controlled-electrolysis oxidation to further remove impurities, this process effectively removes these impurities.

[0025] Figure 1 This is a process flow diagram of the cathode material recycling process in some embodiments of the present invention. For example... Figure 1 As shown, a first aspect of the present invention provides a method for recycling a cathode material, comprising:

[0026] S1: Catalytic oxidation of the positive electrode sheet to obtain intermediate positive electrode material powder and positive electrode current collector;

[0027] S2: Perform controlled-electro-oxidation treatment on the intermediate cathode material powder to obtain cathode material powder;

[0028] The cathode material powder includes Li x Ni y Co z Mn a O2, 0<x≤1.05, 0≤y≤0.9, 0<z≤0.4, 0≤a≤0.5.

[0029] In this invention, the positive electrode sheet can be any commonly used positive electrode sheet in the art. In some embodiments, the positive electrode sheet can be a positive electrode sheet obtained through refined disassembly after battery discharge. The positive electrode material in the positive electrode sheet may include Li. x Ni y Co z Mn a O2, 0<x≤1.05, 0≤y≤0.9, 0<z≤0.4, 0≤a≤0.5, y+z+a=1, and the positive current collector can be aluminum foil commonly used in this field.

[0030] This disclosure provides a method for recycling cathode materials, including: catalytic oxidation and controlled-electrode oxidation of the cathode sheet. In this embodiment, catalytic oxidation selectively decomposes the binder and electrolyte organic matter in the cathode active layer using oxidants such as ozone under the action of a catalyst, separating the cathode active layer from the cathode current collector to obtain intermediate cathode material powder and the cathode current collector. Controlled-electrode oxidation further removes residual copper and aluminum impurities by adjusting the solution potential and pH value, thereby obtaining high-purity cathode material powder. This method achieves synergistic optimization of cathode material separation and purification through staged oxidation treatment, solving problems such as low separation efficiency of the cathode active layer and cathode current collector, high impurity residue in the obtained cathode material, and equipment corrosion in the prior art.

[0031] The recycling method of the present invention can process positive electrode sheets of various types and sizes. The separation effect between the positive electrode material powder and the positive electrode current collector is excellent, and the impurity content in the obtained positive electrode material powder is low. The recycling method is highly efficient, low-cost, and environmentally friendly.

[0032] In some embodiments, the oxidant in the catalytic oxidation treatment and the controlled electro-oxidation treatment may independently include at least one of ozone, sodium sulfate, sodium chlorate and chlorine.

[0033] In one specific embodiment, the positive electrode sheet is further washed before step S1. In this embodiment, the positive electrode sheet is soaked in deionized water and stirred by a circulating pump, allowing the soluble electrolyte to be fully dissolved and peeled off from the surface of the positive electrode sheet. This step, through the synergistic effect of physical washing and mechanical stirring, avoids the use of organic solvents, reduces processing costs, and minimizes the risk of secondary pollution. In some embodiments, by controlling the circulation rate of deionized water and the soaking time, more soluble electrolyte residues can be effectively removed, providing a clean reaction interface for subsequent catalytic oxidation.

[0034] In some embodiments of the present invention, when 1≤x≤1.05, the recovered cathode material powder has higher economic benefits.

[0035] In one specific embodiment, the cathode material powder includes lithium cobalt oxide. In this embodiment, the catalytic oxidation treatment utilizes the inherent catalytic properties of lithium cobalt oxide. The cobalt-based catalyst and the active sites on the surface of lithium cobalt oxide work synergistically, enabling hydroxyl radicals to selectively attack the polyvinylidene fluoride (PVDF) molecular chains in the binder, decomposing them into small-molecule organic acids, thereby destroying the binder structure and releasing the active material. In some embodiments, the decomposition rate of the binder can reach over 98%, and only a dense alumina film forms on the surface of the cathode current collector without embrittlement, achieving the dual objectives of cathode material separation and cathode current collector recovery.

[0036] In one specific embodiment, in the catalytic oxidation process, the catalyst is a cobalt-based catalyst with a concentration of 50-100 ppm; and / or, the oxidant flow rate is 2-10 g / h. In this embodiment, the selection of the cobalt-based catalyst concentration range is based on a balance between catalytic efficiency and cost. Within this range, catalytic efficiency can be improved, costs reduced, and excessive impurities introduced into the reaction system not introduced. Controlling the ozone flow rate within the range of 2-10 g / h ensures maximum synergistic effect between the oxidant and the catalyst, and also avoids structural damage to lithium cobalt oxide caused by over-oxidation.

[0037] In one specific embodiment, the catalytic oxidation treatment lasts for 1-5 hours at a pH of 6.5-7.5. In this embodiment, the synergistic control of reaction time and pH is crucial: within the pH range of 6.5-7.5, the formation rate of the alumina film on the surface of the positive electrode current collector (e.g., aluminum foil) reaches a balance with the decomposition rate of the binder, thus protecting the integrity of the aluminum foil while ensuring the peeling efficiency of the positive electrode material.

[0038] In one specific embodiment, the controlled-electro-oxidation process involves an oxygen flow rate of 0.05-0.1 g / h, a reaction potential <0.35 V, a time of 10-30 min, and a pH of 5-6. In this embodiment, controlled-electro-oxidation selectively dissolves residual copper and aluminum particles in the intermediate cathode powder by adjusting the pure oxygen flow rate (0.05-0.1 g / h) and the solution potential (<0.35 V). This step uses cyclic voltammetry (CV) to monitor potential changes in real time, combined with ICP-MS detection of impurity content, to ensure that the final cathode powder contains <50 ppm copper and <200 ppm aluminum, meeting the purity requirements for regenerated lithium cobalt oxide.

[0039] In one specific embodiment, after S2, the process further includes: mixing the cathode material powder with a raw material comprising at least a lithium source, followed by calcination to obtain a regenerated cathode material. In this embodiment, the lithium source can be a lithium-containing compound commonly used in the art. Exemplarily, the lithium source can be lithium carbonate (Li2CO3) and / or lithium hydroxide (LiOH·H2O).

[0040] This invention improves the specific capacity of the recycled material by mixing cathode material powder with a lithium source and then calcining it. Through thermodynamic regulation, the redistribution of lithium ions within the lithium cobalt oxide lattice is promoted, repairing structural defects in the cathode material. Furthermore, the calcination process further removes conductive agents from the cathode material powder.

[0041] In this invention, the amount of lithium source added can be adjusted according to the molar ratio (Li / Co) of lithium to cobalt in the cathode material powder. The mixing process can employ a planetary ball mill to ensure uniform mixing of the lithium source and the cathode material powder. The calcination process can be carried out in a muffle furnace.

[0042] In one specific embodiment, the raw material further includes a coating source, wherein the coating element in the coating source includes at least one of Mg, Ti, and Zr. In this embodiment, the coating element can be added in the form of MgO (particle size 0.1-0.5 μm), TiO2 (nanoscale), or ZrO2 (micrometer scale), and the amount added can be 0.5-3% of the mass of the cathode material powder.

[0043] In one specific embodiment, the calcination process is carried out at a temperature of 700-1000℃ for 5-22 hours. In this embodiment, the coordinated control of temperature and time is based on the lattice repair kinetics of lithium cobalt oxide. The aforementioned temperature and time can restore the lattice parameters of lithium cobalt oxide to their original state while maintaining the stability of the particle size distribution.

[0044] A second aspect of the present invention provides a cathode material recovery system for implementing the first aspect, comprising a catalytic oxidation unit and a controlled-electro-oxidation unit; the catalytic oxidation unit has a cathode current collector outlet, and the intermediate cathode powder outlet of the catalytic oxidation unit is connected to the inlet of the controlled-electro-oxidation unit.

[0045] In this embodiment, the catalytic oxidation unit can be a continuous reaction tank (5-20L volume), equipped with an ozone injection pipe (10mm inner diameter) and an automatic pH adjustment system (accuracy ±0.1); the controlled-electro-oxidation unit can be a batch reactor (2-10L volume), integrating a potential sensor (0.1mV resolution) and a pure oxygen inlet device (flowmeter accuracy ±0.01g / h). The two units are connected by corrosion-resistant pipes (made of PTFE) to ensure no secondary pollution during material transfer. During system operation, the positive electrode sheet is washed and then enters the catalytic oxidation unit. The processed intermediate product is separated into positive electrode current collectors by a sieving device (pore size 50-100μm) to obtain intermediate positive electrode powder. The intermediate positive electrode powder is then transported to the controlled-electro-oxidation unit for purification. Finally, the positive electrode material powder is collected by a cyclone separator, achieving fully automated control of the entire process.

[0046] The present invention will be further described below with reference to specific embodiments.

[0047] Example 1

[0048] The method for recycling the cathode material in this embodiment includes:

[0049] 1) The positive electrode sheet is obtained by fully discharging the waste lithium cobalt oxide battery and then refining it to achieve effective separation of the positive and negative electrodes.

[0050] 2) Take 100g of positive electrode sheet and immerse it in the reaction tank. 500g of deionized water is introduced as the immersion solution. Turn on the circulation pump in the reaction tank to enhance the contact reaction between the solution and the positive electrode sheet. The soluble electrolyte is thoroughly washed and dissolved in the water to initially separate from the positive electrode sheet, thereby reducing the content of organic impurities in the positive electrode active layer.

[0051] 3) Add 500g of deionized water and cobalt sulfate to the catalytic oxidation tank and adjust the cobalt sulfate concentration to 100mg / L; turn on the ozone generator and control the ozone amount at 10g / h through the flow meter, the reaction time at 4h, the solution pH at 6.5, the positive electrode active layer gradually falls off and separates from the aluminum foil, and the intermediate positive electrode material powder and the positive electrode current collector aluminum foil are obtained.

[0052] 4) The obtained intermediate cathode material powder and aluminum foil are separated by sieving. The intermediate cathode material powder is transferred to an electrostatic oxidation tank. 500g of deionized water is introduced as the electrostatic oxidation reaction solution. Dilute sulfuric acid is added to make the solution pH 5. The pure oxygen generator is turned on and the pure oxygen quantity is controlled at 0.1g / h by the flow meter. The solution reaction potential is always controlled at <0.35V and the reaction time is 30min to ensure that the small amount of copper and aluminum remaining in the cathode powder are immersed in the solution. After filtration, high-purity lithium cobalt oxide cathode powder (cathode material powder) is obtained.

[0053] 5) The lithium cobalt oxide cathode powder obtained by separation and purification is supplemented with lithium carbonate lithium salt at a lithium-cobalt molar ratio of 1.05, and MgO is added as a dopant. The molar ratio of Mg to Co is 0.02. After being mixed evenly with high-purity cathode material, it is evaporated and dried to obtain coated lithium cobalt oxide powder.

[0054] 6) The coated lithium cobalt oxide powder was sintered at a heat treatment temperature of 900℃ for 15h to obtain the repaired and regenerated high-voltage lithium cobalt oxide cathode material.

[0055] Example 2

[0056] The method for recycling the cathode material in this embodiment includes:

[0057] 1) The positive electrode sheet is obtained by fully discharging the waste lithium cobalt oxide battery and then refining it to achieve effective separation of the positive and negative electrodes.

[0058] 2) Take 100g of positive electrode sheet and immerse it in the reaction tank. 500g of deionized water is introduced as the immersion solution. Turn on the circulation pump in the reaction tank to enhance the contact reaction between the solution and the positive electrode sheet. The soluble electrolyte is thoroughly washed and dissolved in the water to initially separate from the positive electrode sheet, thereby reducing the content of organic impurities in the positive electrode active layer.

[0059] 3) Add 500g of deionized water and cobalt sulfate to the catalytic oxidation tank and adjust the cobalt sulfate concentration to 100mg / L; turn on the ozone generator and control the ozone amount at 8g / h through the flow meter, the reaction time at 4h, the solution pH at 7, the positive electrode active layer gradually falls off and separates from the aluminum foil, and the intermediate positive electrode material powder and the positive electrode current collector aluminum foil are obtained.

[0060] 4) The obtained intermediate cathode material powder and aluminum foil are separated by sieving. The intermediate cathode material powder is transferred to the controlled oxidation tank. 500g of deionized water is introduced as the controlled oxidation reaction solution. Dilute sulfuric acid is added to make the solution pH 5. The pure oxygen generator is turned on and the pure oxygen quantity is controlled at 0.08g / h by the flow meter. The solution reaction potential is always controlled at <0.35V and the reaction time is 30min to ensure that the small amount of copper and aluminum remaining in the cathode powder are immersed in the solution. The high-purity lithium cobalt oxide cathode powder is obtained by filtration.

[0061] 5) The lithium cobalt oxide cathode powder obtained by separation and purification is supplemented with lithium carbonate lithium salt at a lithium cobalt molar ratio of 1.05, and MgO is added as a dopant at the same time. The molar ratio of Mg to Co is 0.02. After being mixed evenly with high-purity cathode material, it is evaporated and dried to obtain coated lithium cobalt oxide powder.

[0062] 6) The coated lithium cobalt oxide powder was sintered at a heat treatment temperature of 900℃ for 15h to obtain the repaired and regenerated high-voltage lithium cobalt oxide cathode material.

[0063] Example 3

[0064] The method for recycling the cathode material in this embodiment includes:

[0065] 1) The positive electrode sheet is obtained by fully discharging the waste lithium cobalt oxide battery and then refining it to achieve effective separation of the positive and negative electrodes.

[0066] 2) Take 100g of positive electrode sheet and immerse it in the reaction tank. 500g of deionized water is introduced as the immersion solution. Turn on the circulation pump in the reaction tank to enhance the contact reaction between the solution and the positive electrode sheet. The soluble electrolyte is thoroughly washed and dissolved in the water to initially separate from the positive electrode sheet, thereby reducing the content of organic impurities in the positive electrode active layer.

[0067] 3) Add 500g of deionized water and cobalt sulfate to the catalytic oxidation tank and adjust the cobalt sulfate concentration to 80mg / L; turn on the ozone generator and control the ozone amount to 6g / h through the flow meter, the reaction time to 4h, the solution pH to 6.5, the positive electrode active layer gradually falls off and separates from the aluminum foil, and the intermediate positive electrode material powder and the positive electrode current collector aluminum foil are obtained.

[0068] 4) The obtained intermediate cathode material powder and aluminum foil are separated by sieving. The intermediate cathode material powder is transferred to the controlled oxidation tank. 500g of deionized water is introduced as the controlled oxidation reaction solution. Dilute sulfuric acid is added to make the solution pH 5. The pure oxygen generator is turned on and the pure oxygen quantity is controlled at 0.06g / h by the flow meter. The solution reaction potential is always controlled at <0.35V and the reaction time is 30min to ensure that the small amount of copper and aluminum remaining in the cathode powder are immersed in the solution. The high-purity lithium cobalt oxide cathode powder is obtained by filtration.

[0069] 5) The lithium cobalt oxide cathode powder obtained by separation and purification is supplemented with lithium carbonate and lithium salt at a lithium-cobalt molar ratio of 1.05, and MgO is added as a dopant at the same time. The Mg / Co molar ratio is 0.02. After being mixed evenly with high-purity cathode material, it is evaporated and dried to obtain coated lithium cobalt oxide powder.

[0070] 6) The coated lithium cobalt oxide powder is sintered at a heat treatment temperature of 700-1000℃ for 15h to obtain the repaired and regenerated high-voltage lithium cobalt oxide cathode material.

[0071] Example 4

[0072] The method for recycling the cathode material in this embodiment includes:

[0073] 1) The positive electrode sheet is obtained by fully discharging the waste lithium cobalt oxide battery and then refining it to achieve effective separation of the positive and negative electrodes.

[0074] 2) Take 100g of positive electrode sheet and immerse it in the reaction tank. 500g of deionized water is introduced as the immersion solution. Turn on the circulation pump in the reaction tank to enhance the contact reaction between the solution and the positive electrode sheet. The soluble electrolyte is thoroughly washed and dissolved in the water to initially separate from the positive electrode sheet, thereby reducing the content of organic impurities in the positive electrode active layer.

[0075] 3) Add 500g of deionized water and cobalt sulfate to the catalytic oxidation tank, and adjust the cobalt sulfate concentration to 50-100mg / L; turn on the ozone generator, control the ozone amount to 4g / h through the flow meter, the reaction time to 4h, the solution pH to 6.5, the positive electrode active layer gradually falls off and separates from the aluminum foil, and the intermediate positive electrode material powder and the positive electrode current collector aluminum foil are obtained.

[0076] 4) The obtained intermediate cathode material powder and aluminum foil are separated by sieving. The intermediate cathode material powder is transferred to the controlled oxidation tank. 500g of deionized water is introduced as the controlled oxidation reaction solution. Dilute sulfuric acid is added to make the solution pH 5. The pure oxygen generator is turned on and the pure oxygen quantity is controlled at 0.04g / h by the flow meter. The solution reaction potential is always controlled at <0.35V and the reaction time is 30min to ensure that the small amount of copper and aluminum remaining in the cathode powder are immersed in the solution. The high-purity lithium cobalt oxide cathode powder is obtained by filtration.

[0077] 5) The lithium cobalt oxide cathode powder obtained by separation and purification is supplemented with lithium carbonate at a lithium cobalt molar ratio of 1.05, and MgO is added as a dopant at the same time. The Mg to Co molar ratio is 0.02. After being mixed evenly with the high-purity cathode material, it is evaporated and dried to obtain coated lithium cobalt oxide powder.

[0078] 6) The coated lithium cobalt oxide powder was sintered at a heat treatment temperature of 900℃ for 15h to obtain the repaired and regenerated high-voltage lithium cobalt oxide cathode material.

[0079] Test Example 1

[0080] In this test example, the contents of Co, Li, Cu, and Al in the positive electrode active layer after washing in step 2) of Example 1 and the intermediate positive electrode material powder separated after catalytic oxidation in steps 3) of Examples 1-4 were determined by ICP-MS, the contents of PVDF were determined by TGA, and the contents of other organic compounds were determined by solvent extraction and TOC analysis. The test results are shown in Table 1.

[0081] Table 1

[0082]

[0083] As can be seen from Table 1, catalytic oxidation treatment can reduce the content of binders and other organic matter in the positive electrode active layer.

[0084] Test Example 2

[0085] This test example tests the cathode material powder (high-purity lithium cobalt oxide cathode powder) obtained after separation following controlled electro-oxidation in steps 4) of Examples 1-4 (refer to the test method in Test Example 1). The test results are shown in Table 2.

[0086] Table 2

[0087]

[0088] Test Example 3

[0089] This test example tests the key indicators of the recycled cathode material (high-voltage lithium cobalt oxide cathode material) obtained in step 6) of Examples 1-4. The test results are shown in Table 3. The test process is as follows, please refer to the button cell test method GB / T23365-2023 for details.

[0090] Battery assembly:

[0091] 1) The obtained recycled cathode material is used to prepare cathode sheets by following the steps of batching, homogenization, coating, drying, pressing, and cutting according to the button cell testing method;

[0092] The positive electrode sheet includes an aluminum foil and a positive electrode active layer located on the surface of the aluminum foil. The positive electrode active layer includes recycled positive electrode material, conductive carbon black, and PVDF, and the mass ratio of recycled positive electrode material, conductive carbon black, and PVDF is 98:1:1.

[0093] 2) The obtained standard-sized positive electrode sheet is then used for coin cell assembly. The CR2032 coin cell has a counter electrode / reference electrode of lithium metal sheet, an electrolyte of 1M LiPF6, and solvents of EC and DMC with a volume ratio of 1:1.

[0094] Electrochemical performance testing

[0095] 1) First-time efficiency

[0096] Test Procedure: First Charge: Charge at a constant current of 0.2C to 4.5V, then charge at a constant voltage until the current ≤0.05C. Let stand for 5 minutes and record the first charge capacity; First Discharge: Discharge at a constant current of 0.2C to 3.0V. Record this capacity, which is the 0.2C discharge specific capacity (first discharge specific capacity). The first efficiency can be calculated.

[0097] 2) 1C discharge specific capacity

[0098] Charge using a 1C constant current to the upper limit voltage of 4.5V, then maintain the voltage until the cutoff current is ≤0.05C; allow to discharge: discharge using a 1C constant current to the cutoff voltage of 3.0V. Record this discharge capacity, which is the 1C discharge specific capacity.

[0099] Table 3

[0100]

[0101] As shown in Tables 1-3, high-purity cathode material powder can be obtained by sequentially subjecting the cathode sheet to catalytic oxidation and controlled-electrode oxidation. The regenerated cathode material obtained by mixing the cathode material powder with a lithium source and then calcining it exhibits excellent capacity and first-time efficiency. This demonstrates that the cathode material recovery method of the present invention can efficiently and economically recover cathode material from cathode sheets, and the obtained cathode material powder has high purity and excellent electrochemical performance after regeneration, possessing significant economic value.

[0102] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A method for recycling a cathode material, characterized by, include: S1: Catalytic oxidation of the positive electrode sheet to obtain intermediate positive electrode material powder and positive electrode current collector; S2: Perform controlled-electro-oxidation treatment on the intermediate cathode material powder to obtain cathode material powder; The positive electrode material powder comprises Li x Ni y Co z Mn a O2, 0 < x < 1.05, 0 < y < 0.9, 0 < z < 0.4, 0 < a < 0.

5.

2. The recycling method according to claim 1, characterized in that, The process before S1 also includes washing the positive electrode sheet.

3. The recycling method according to claim 1 or 2, characterized in that... 1 ≤ x ≤ 1.05; and / or, the cathode material powder includes lithium cobalt oxide.

4. The recycling method according to claim 3, characterized in that, In the catalytic oxidation treatment, the catalyst is a cobalt-based catalyst, and the concentration of the cobalt-based catalyst is 50-100 ppm; and / or, The flow rate of the oxidant is 2-10 g / h.

5. The recycling method according to claim 3 or 4, characterized in that, In the catalytic oxidation treatment, the time is 1-5 hours and the pH is 6.5-7.

5.

6. The recycling method according to any one of claims 3-5, characterized in that, In the controlled oxidation treatment, the oxygen flow rate is 0.05-0.1 g / h, the reaction potential is <0.35 V, the time is 10-30 min, and the pH is 5-6.

7. The recycling method according to any one of claims 1-6, characterized in that, Following S2 are: The cathode material powder is mixed with raw materials including at least a lithium source and then calcined to obtain a recycled cathode material.

8. The recycling method according to claim 7, characterized in that, The raw material also includes a coating source, wherein the coating element in the coating source includes at least one of Mg, Ti and Zr.

9. The recycling method according to claim 7 or 8, characterized in that, The roasting process is carried out at a temperature of 700-1000℃ for 5-22 hours.

10. A recycling system for implementing the method for recycling the cathode material according to any one of claims 1-9, characterized in that, Includes catalytic oxidation units and electro-controlled oxidation units; The catalytic oxidation unit has a positive electrode current collector outlet, and the intermediate positive electrode powder outlet of the catalytic oxidation unit is connected to the inlet of the electro-controlled oxidation unit.

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