A method for homogenizing and recycling the cathode material of waste lithium-ion batteries

Abstract

The present invention discloses a method for homogenizing and recycling the cathode material of waste lithium-ion batteries. In this method, the cathode material of failed lithium-ion batteries is subjected to high-energy ball milling and then classified by a liquid-phase cyclone force field to select cathode material powder with a D90 of the micron level. The cathode material powder is first subjected to pre-oxidation calcination, and then the corresponding lithium source and transition metal source are supplemented according to the metal element ratio in the target recycled cathode material for secondary calcination, thus obtaining the recycled cathode material. This method can achieve the transformation of different types of waste low-series ternary cathode materials into a unified high-series ternary cathode material, and can also induce the transformation of lithium iron phosphate with different scales into lithium iron phosphate with a uniform scale, completing the homogenization and homogeneous phase recycling. This method is simple to operate and has a short cycle. After the obtained recycled battery material is reassembled into a full battery, it exhibits electrochemical performance comparable to that of a full battery assembled with commercial electrode materials.

Description

Technical Field

[0001] The present invention relates to a method for homogenizing and recycling the cathode material of waste lithium-ion batteries, and particularly to a method for repairing the cathode material of waste lithium-ion batteries by regulating the particle size, finely matching the elements, and optimizing the sintering process, belonging to the technical field of waste battery recycling. Background Art

[0002] According to predictions, by 2030, the retirement volume of failed batteries can reach 2.8 million tons. Since waste batteries contain substances such as electrolytes and heavy metal elements that are highly harmful to the environment, properly handling waste lithium-ion batteries is crucial for environmental protection in China. In addition, it has been found that waste batteries contain nearly 40% of cathode powder, and its main constituent elements include valuable elements such as lithium, nickel, cobalt, and manganese. Effective recycling is of great significance for the high-value utilization of waste batteries. Currently, for the recycling of waste batteries, enterprises mostly adopt element separation methods, that is, the process of extracting valuable elements through pyrometallurgy or hydrometallurgy, and then performing process operations such as extraction, separation, purification, and crystallization, and finally obtaining a corresponding metal salt system that meets market requirements, such as lithium carbonate, lithium hydroxide, nickel sulfate, cobalt sulfate, etc. Subsequently, the obtained salts are further applied for high-value utilization of waste battery materials through the method of synthesizing new energy materials. However, this process inevitably undergoes a complex process and has a relatively large potential harm to the environment. Generally speaking, this type of method can be summarized as the process steps of "material - element - material". Based on this, developing a short-process repair and regeneration of failed battery materials and optimizing the recycling process of waste batteries will contribute to China's early achievement of the dual-carbon goal.

[0003] The direct repair technology mainly refers to the transformation of the failed cathode material into a regenerated cathode material while ensuring the original crystal phase of the material remains unchanged, shortening the traditional recycling repair process to a "material - material" process. The current traditional direct regeneration process mainly refers to the restoration of the crystal phase, structure, coating, etc. of ternary materials through lithium doping or hydrothermal methods. However, in order to pursue high performance of the materials, battery manufacturers often use raw material mixing, that is, the recycled ternary materials show different particle sizes, crystal system structures, and modification characteristics. Therefore, simply using technical means such as sintering to restore the failed materials is difficult to make the failed materials flow into the market. Therefore, developing a homogenization repair technology for dimensions, crystal phases, modifications, etc. is of great significance for the regeneration of waste battery materials. Summary of the Invention

[0004] Aiming at the serious problem of inconsistent product quality after repair caused by the variety of cathode materials and crystal systems of waste lithium-ion batteries in the prior art, the purpose of the present invention is to provide a method for homogenizing and homogenizing the regeneration of waste lithium-ion battery cathode materials. This method can realize the transformation of different types of waste low-system ternary cathode materials into unified high-system ternary cathode materials, and can also induce the transformation of lithium iron phosphate with different scales into lithium iron phosphate with a uniform scale, completing homogenization and homogenization regeneration. This method is simple to operate and has a short cycle. After the corresponding homogenized regenerated battery materials are reassembled into full batteries, they exhibit electrochemical performance comparable to that of full batteries assembled with commercial electrode materials.

[0005] To achieve the above technical purpose, the present invention provides a method for homogenizing the regeneration of waste lithium-ion battery cathode materials. In this method, the cathode materials of failed lithium-ion batteries are subjected to high-energy ball milling and then liquid-phase cyclone force field classification to select the cathode material powder with a D90 of the micron level. The cathode material powder is first subjected to pre-oxidation calcination, and then the corresponding lithium source and transition metal source are supplemented according to the metal element ratio in the target regenerated cathode material for secondary calcination to obtain the regenerated cathode material.

[0006] In the repair process of the cathode materials of failed lithium-ion batteries in the present invention, the size, crystal system structure, and element composition of the cathode materials are simultaneously regulated, realizing the homogenization and homogenization regeneration of the cathode materials of waste lithium-ion batteries. The technical solution of the present invention first performs high-energy ball milling on the cathode materials of failed lithium-ion batteries to complete the dissociation of the cathode materials and perform cyclone force field classification to select the fraction in the best size range. On this basis, the cathode material powder of the best size is subjected to pre-oxidation crystal phase reforming to obtain a cathode material precursor powder with relatively uniform phase and uniform size distribution; then, the metal sources are compounded and mixed, and calcination is performed to induce crystal phase reconstruction and quality improvement, ultimately realizing the homogenization and homogenization regeneration of the failed materials.

[0007] As a preferred solution, the cathode materials of the failed lithium-ion batteries are derived from at least one of ternary cathode materials, lithium manganate materials, and lithium cobaltate materials, or from lithium iron phosphate materials with different particle size scales. The method of the present invention is particularly suitable for the regeneration process of two or more different types of mixed raw materials such as ternary cathode materials, lithium manganate materials, and lithium cobaltate materials to realize the transformation of low-system ternary cathode materials into unified high-system ternary cathode materials.

[0008] As a preferred embodiment, the D90 of the positive electrode material powder is between 0.1 μm and 10 μm. For the positive electrode material of the failed lithium-ion battery in the present invention, after being crushed and understood by high-energy ball milling, the particle size is separated. Through the action of a liquid-phase cyclone force field, rapid separation of the particle size is achieved, and particles with a particle size D90 of 0.3 μm to 10 μm are obtained; further preferably, the mixed particle size D90 is 0.3 μm to 5 μm; further preferably, the mixed particle size D90 is 0.3 μm to 1 μm; when the particle size is too large, it is difficult to achieve effective diffusion of elements between materials of different crystal systems and phases, resulting in the generation of impurities such as heterophases in the regenerated positive electrode material, and it is difficult to achieve homogeneous repair.

[0009] As a preferred embodiment, the conditions for pre-oxidation calcination are: in an oxidizing atmosphere, at a temperature of 600 °C to 1200 °C, calcined for 0.5 h to 30 h. The oxidizing atmosphere is preferably an air atmosphere. High-temperature pre-calcination of the failed positive electrode material powder is carried out in an air atmosphere for crystal phase reforming, and the heating rate is 5 - 15 °C / min. -1 The calcination temperature is further preferably 600 - 1000 °C; most preferably 700 - 1000 °C. The calcination time is further preferably 0.5 h to 20 h; most preferably 3 h to 8 h. Excessively high calcination temperature and too long calcination time will cause the positive electrode material of the failed lithium battery to agglomerate; while too low calcination temperature and too short calcination time will make it difficult for the crystal phase in the failed lithium-ion battery positive electrode powder to undergo reforming, and it is difficult to remove carbon components and other organic impurities.

[0010] As a preferred embodiment, the lithium source includes at least one of lithium carbonate, lithium hydroxide, and lithium nitrate.

[0011] As a preferred embodiment, the transition metal source includes at least one of a nickel source, a cobalt source, a manganese source, and an iron source. The nickel source mainly includes at least one of nickel hydroxide, nickel nitrate, nickel carbonate, and nickel oxide. The manganese source mainly includes at least one of manganese hydroxide, manganese monoxide, manganese nitrate, and manganese carbonate. The cobalt source mainly includes at least one of cobalt hydroxide, cobalt oxide, cobalt nitrate, and cobalt carbonate. The iron source mainly includes at least one of iron phosphate, iron hydroxide, and iron carbonate. These transition metal sources are all conventional raw materials in the prior art.

[0012] As a more preferred embodiment, the lithium source and the transition metal source have the same anion. By compounding metal sources with the same anion, the capture and bonding ability of different anions for other metal ions can be avoided, and uniform interaction between metal ions in the positive electrode material is expected to be achieved, improving the homogenization degree of the positive electrode material.

[0013] As a preferred solution, when the cathode material of the failed lithium-ion battery is derived from lithium iron phosphate materials with different particle size scales, the metal source further includes a phosphorus source, which mainly includes at least one of ammonium phosphate and ammonium dihydrogen phosphate.

[0014] As a preferred solution, when the cathode material of the failed lithium-ion battery is derived from at least one of ternary cathode materials, lithium manganate materials, and lithium cobaltate materials, the conditions for the secondary calcination are: in an oxidizing atmosphere, first calcine at 350°C to 450°C for 3h to 6h, and then calcine at 800°C to 1000°C for 10h to 16h; too low a calcination temperature and too short a calcination time are difficult to induce the pulverized precursor material to recrystallize and form a new phase. Too high a calcination temperature and too long a calcination time will cause excessive fusion between materials, resulting in an increase in the size of the regenerated particles and poor final electrochemical performance. The oxidizing atmosphere is, for example, a pure oxygen atmosphere.

[0015] As a preferred solution, when the cathode material of the failed lithium-ion battery is derived from lithium iron phosphate materials with different particle size scales, the conditions for the secondary calcination are: add a carbonaceous reducing agent accounting for 5-15% of the mass of the cathode material of the failed lithium-ion battery, first calcine at 300°C to 400°C for 3h to 6h, and then calcine at 650°C to 750°C for 6h to 10h. If too low a calcination temperature and too short a calcination time are used, it is difficult to induce the pulverized precursor material to recrystallize and form a new phase. If too high a calcination temperature and too long a calcination time are used, it will cause excessive fusion between materials, resulting in an increase in the size of the regenerated particles and poor final electrochemical performance.

[0016] The high-energy ball milling and cyclone force field classification involved in the present invention are both conventional operation processes in the prior art, and the purpose is to dissociate and classify the cathode material of the failed lithium-ion battery.

[0017] The supplementation of the lithium source and transition metal source in the present invention is to explore the element content in the pre-oxidation calcination product by ICP, perform fine element adjustment, and finally realize the homogenization sintering process of the cathode material of the failed lithium-ion battery. During the element adjustment process, it should be noted that the anions of the substances of the added metal sources should be the same.

[0018] Compared with the prior art, the beneficial technical effects brought by the technical solution of the present invention:

[0019] The repair method of the cathode material of the failed lithium-ion battery provided by the present invention simultaneously completes the regulation of the size, crystal system structure, and element composition of the cathode material, and realizes the homogenization and homophase regeneration of the waste lithium-ion battery cathode material.

[0020] The repair method for the cathode materials of failed lithium-ion batteries provided by the present invention can achieve batch homogenization repair and regeneration of the mixed cathode materials of different types of waste lithium-ion batteries. This method can achieve a one-step transformation of different types of low-series ternary cathode materials into unified high-series ternary cathode materials, and can also induce the transformation of lithium iron phosphate with different scales into lithium iron phosphate with a uniform scale.

[0021] The repair method for the cathode materials of failed lithium-ion batteries provided by the present invention is simple to operate and has a short cycle. After the obtained corresponding homogenized regenerated battery materials are reassembled into full batteries, they exhibit electrochemical performance comparable to that of full batteries assembled with commercial electrode materials. Description of the Drawings

[0022] Figure 1 SEM image of the regenerated cathode material for Example 4.

[0023] Figure 2 XRD pattern of the regenerated cathode material for Example 4.

[0024] Figure 3 Cycling performance graph of the regenerated cathode material for Example 5 used in a lithium battery.

[0025] Figure 4 Charge-discharge platform of the regenerated cathode material for Example 6 used in a lithium battery.

[0026] Figure 5 TEM image of the regenerated cathode material for Example 7 used in a lithium battery. Detailed Description of the Invention

[0027] The following examples are used to illustrate the content of the present invention, but do not limit the protection scope of the claims of the present invention.

[0028] The powder of the cathode material of the failed lithium-ion battery used in the present invention is the failed powder obtained through precise or broken disassembly. The black powder of the cathode material can be purchased on the market.

[0029] Through tests such as ICP, the lithium deficiency amount of the failed cathode material is calculated, and a metal source is used for supplementation to achieve the repair, regeneration, and quality improvement of the cathode material of the failed material.

[0030] Example 1 (Control Example):

[0031] The 532 / 622 / 811 mixture of the obtained failed ternary material was subjected to ICP testing, lithium carbonate was supplemented and added, and after ball milling, it was directly pre-calcined at 450 °C for 3 h in an oxygen atmosphere and calcined at 800 °C for 10 h to obtain a regenerated metal oxide-type cathode material. The regenerated ternary material exhibited a 532 / 622 / 811 crystal system, and the material was repaired, but the crystal phase of the repaired material was not homogeneous, and the battery performance was poor, making it difficult to enter the market for circulation.

[0032] Example 2 (control example):

[0033] The 532 / 622 / 811 mixture of the obtained failed ternary material was used to prepare a high-nickel 811 material. After ball milling, the obtained powder material was subjected to hydrocyclone liquid separation to obtain a failed powder material with a D90 of 1 μm. The large-particle material was further subjected to multi-stage grinding to separate and obtain a material with a D90 of 1 μm. The mixed material was subjected to ICP testing, and lithium carbonate, nickel hydroxide, cobalt carbonate, and manganese nitrate elements were supplemented and added. It was directly pre-calcined at 450 °C for 3 h in an oxygen atmosphere and calcined at 800 °C for 10 h to obtain a preliminarily homogeneous regenerated 811-series ternary cathode material. In the regenerated ternary cathode material, some crystal phases were not completely fused, and impurity phases and other substances were generated.

[0034] Example 3 (control example):

[0035] The 532 / 622 / 811 mixture of the obtained failed ternary material was used to prepare a high-nickel 811 material. The obtained mixed powder of the failed ternary material was pre-oxidized by calcination at 800 °C for 5 h to obtain a precursor material; subsequently, ICP testing was carried out, and lithium hydroxide, cobalt hydroxide, and manganese hydroxide elements were supplemented and added. It was directly pre-calcined at 450 °C for 3 h in an oxygen atmosphere and calcined at 800 °C for 10 h to obtain a preliminarily homogeneous regenerated 811-series ternary cathode material. In the regenerated ternary cathode material, some crystal phases were not completely fused, and impurity phases and other substances were generated.

[0036] Example 4:

[0037] 1. The 532 / 622 / 811 mixture of the obtained failed ternary material was used to prepare a high-nickel 811 material. After ball milling, the obtained powder material was subjected to hydrocyclone liquid separation to obtain a failed powder material with a D90 of 1 μm. The large-particle material was further subjected to multi-stage grinding to separate and obtain a material with a D90 of 1 μm.

[0038] 2. The obtained mixed powder of the failed ternary material was pre-oxidized by calcination at 800 °C for 5 h in an oxygen atmosphere to obtain a precursor material;

[0039] 3. Explore the ICP of the failed precursor, compare it with the elemental ratio of the 811 series materials, supplement the obtained precursor material with lithium hydroxide, nickel hydroxide, cobalt hydroxide, and manganese hydroxide elements, perform a pre-calcination at 450 °C for 3 h in an oxygen atmosphere after ball milling, calcine at 800 °C for 10 h, and after grinding, a homogenized regenerated 811 ternary material can be obtained.

[0040] Example 5:

[0041] 1. Prepare a high-grade 811 material from the 532 / 622 / 811 mixture of the obtained failed ternary material. After ball milling, perform a hydrocyclone liquid-phase separation on the obtained powder material to obtain a failed powder material with a D90 of 10 μm. Further perform multi-stage grinding on the large-particle material to separate and obtain a material with a D90 of 10 μm.

[0042] 2. Pre-oxidize the obtained mixed powder of the failed ternary material by calcining at 800 °C for 5 h in an oxygen atmosphere to obtain a precursor material;

[0043] 3. Explore the ICP of the failed precursor, compare it with the elemental ratio of the 811 series materials, supplement the obtained precursor material with lithium hydroxide, nickel hydroxide, cobalt hydroxide, and manganese hydroxide elements, perform a pre-calcination at 450 °C for 3 h in an oxygen atmosphere after ball milling, calcine at 800 °C for 10 h, and after grinding, a homogenized regenerated 811 ternary material can be obtained.

[0044] Example 6:

[0045] 1. Prepare a high-grade 811 material from the 532 / 622 / 811 mixture of the obtained failed ternary material. After ball milling, perform a hydrocyclone liquid-phase separation on the obtained powder material to obtain a failed powder material with a D90 of 0.1 μm. Further perform multi-stage grinding on the large-particle material to separate and obtain a material with a D90 of 0.1 μm.

[0046] 2. Pre-oxidize the obtained mixed powder of the failed ternary material by calcining at 800 °C for 5 h in an oxygen atmosphere to obtain a precursor material;

[0047] 3. Explore the ICP of the failed precursor, compare it with the elemental ratio of the 811 series materials, supplement the obtained precursor material with lithium hydroxide, nickel hydroxide, cobalt hydroxide, and manganese hydroxide elements, perform a pre-calcination at 450 °C for 3 h in an oxygen atmosphere after ball milling, calcine at 800 °C for 10 h, and after grinding, a homogenized regenerated 811 ternary material can be obtained.

[0048] Example 7:

[0049] 1. Prepare high-nickel 811 material from the 532 / 622 / 811 mixture of the obtained failed ternary material. After ball milling, perform hydrocyclone liquid-phase separation on the obtained powder material to obtain a failed powder material with a D90 of 1.0 μm. Further perform multi-stage grinding on the large-particle material to separate and obtain a material with a D90 of 1.0 μm.

[0050] 2. Calcinate the obtained mixed powder of the failed ternary material at 1200 °C for 30 h under an oxygen atmosphere for pre-oxidation to obtain a precursor material.

[0051] 3. Explore the ICP of the failed precursor and compare it with the elemental ratio of the 811 series material. Supplement the obtained precursor material with elements such as lithium hydroxide, nickel hydroxide, cobalt hydroxide, and manganese hydroxide. After ball milling, pre-calcine at 450 °C for 3 h in an oxygen atmosphere and calcine at 800 °C for 10 h. After grinding, a homogenized regenerated 811 ternary material can be obtained.

[0052] Example 8:

[0053] 1. Prepare high-nickel 811 material from the 532 / 622 / 811 mixture of the obtained failed ternary material. After ball milling, perform hydrocyclone liquid-phase separation on the obtained powder material to obtain a failed powder material with a D90 of 1.0 μm. Further perform multi-stage grinding on the large-particle material to separate and obtain a material with a D90 of 1.0 μm.

[0054] 2. Calcinate the obtained mixed powder of the failed ternary material at 600 °C for 0.5 h under an oxygen atmosphere for pre-oxidation to obtain a precursor material.

[0055] 3. Explore the ICP of the failed precursor and compare it with the elemental ratio of the 811 series material. Supplement the obtained precursor material with elements such as lithium hydroxide, nickel hydroxide, cobalt hydroxide, and manganese hydroxide. After ball milling, pre-calcine at 450 °C for 3 h in an oxygen atmosphere and calcine at 800 °C for 10 h. After grinding, a homogenized regenerated 811 ternary material can be obtained.

[0056] Example 9:

[0057] 1. Prepare high-nickel 811 material from the 532 / 622 / 811 mixture of the obtained failed ternary material. After ball milling, perform hydrocyclone liquid-phase separation on the obtained powder material to obtain a failed powder material with a D90 of 1.0 μm. Further perform multi-stage grinding on the large-particle material to separate and obtain a material with a D90 of 1.0 μm;

[0058] 2. Calcinate the obtained mixed powder of the failed ternary material at 800 °C for 5 h under an oxygen atmosphere for pre-oxidation to obtain a precursor material.

[0059] 3. Explore the ICP of the failed precursor, compare it with the elemental ratio of the 811 series materials, supplement the obtained precursor material with elements such as lithium hydroxide, nickel carbonate, cobalt nitrate, and manganese oxide, perform ball milling, then pre-calcine at 450 °C for 3 h in an oxygen atmosphere, and calcine at 800 °C for 10 h. After grinding, a homogenized regenerated 811 ternary material can be obtained.

[0060] Example 10:

[0061] 1. Prepare a high-system 811 material from the 532 / 622 / 811 mixture of the obtained failed ternary material. After ball milling, perform hydrocyclone liquid-phase separation on the obtained powder material to obtain a failed powder material with a D90 of 1.0 μm. Further perform multi-stage grinding on the large-particle material to separate and obtain a material with a D90 of 1.0 μm.

[0062] 2. Pre-oxidize the obtained mixed powder of the failed ternary material by calcining at 800 °C for 5 h in an oxygen atmosphere to obtain a precursor material.

[0063] 3. Explore the ICP of the failed precursor, compare it with the elemental ratio of the 811 series materials, supplement the obtained precursor material with elements such as lithium hydroxide, nickel carbonate, cobalt nitrate, and manganese oxide, perform ball milling, then pre-calcine at 450 °C for 3 h in an oxygen atmosphere, and calcine at 800 °C for 10 h. After grinding, a homogenized regenerated 811 ternary material can be obtained.

[0064] Example 11:

[0065] 1. Prepare a homogenized lithium iron phosphate material from the mixture of the obtained failed lithium iron phosphate materials with different scales. After ball milling, perform hydrocyclone liquid-phase separation on the obtained powder material to obtain a failed powder material with a D90 of 1.0 μm. Further perform multi-stage grinding on the large-particle material to separate and obtain a material with a D90 of 1.0 μm.

[0066] 2. Pre-oxidize the obtained mixed powder of the failed ternary material by calcining at 800 °C for 5 h to obtain a precursor material.

[0067] 3. Explore the ICP of the failed precursor, compare it with the elemental ratio of the lithium iron phosphate material, mix the obtained lithium iron phosphate precursor powder material with the corresponding iron source and lithium source, and add 10% of the carbon source as a coating agent and reducing agent. Pre-calcine at 300 °C for 3 h and calcine at 700 °C for 10 h to obtain a homogenized regenerated lithium iron phosphate cathode material.

[0068] Example 12

[0069] 1. Sample:

[0070] In each embodiment, the failed battery material is the battery black powder obtained from the market, which is processed into a homogenized positive electrode material regeneration material. The original material, acetylene black, and polyvinylidene fluoride (PVDF) are mixed in a mass ratio of 8 / 1 / 1, and a certain amount of NMP is added to prepare a uniform slurry. The obtained slurry is coated on an aluminum foil and then dried in a vacuum oven at 100 °C for 24 h. The obtained electrode sheet is cut by a slicing machine into small round pieces with a diameter of 1 cm to obtain the negative electrode material, where the aluminum foil is loaded with more than 1 mg of active substance.

[0071] The obtained positive electrode sheet, electrolyte, lithium sheet, battery case, separator, etc. are placed in an argon glove box for battery assembly. After sealing, the obtained battery is the assembled button cell.

[0072] Note: The above electrode material preparation method is used in all embodiments.

[0073] 2. Experimental method:

[0074] After the obtained button cell is left standing for 12 h, it is placed on a Blue Power test channel for electrochemical performance testing, where the current density is set to 0.2 Ag -1 , the voltage range is set to 3.0 V - 4.3 V, and the number of test cycles is 100 cycles. The obtained data is directly displayed on the Blue Power tester and can be directly taken.

[0075] 3. Detection results: See Table 1:

[0076] Table 1: Metal salts, precursor D90, pre-sintering process, and detection results in each embodiment

[0077]

[0078]

[0079]

[0080] The results in Table 1 show that through relevant data, it can be found that after repair, the failed positive electrode material can be effectively repaired and exhibits good electrochemical performance. From the control examples, it can be seen that if the failed positive electrode material is not subjected to high-energy ball milling and classification or pre-oxidation crystal phase reforming, it is difficult to obtain a regenerated positive electrode material with relatively uniform phase and uniform size distribution. At the same time, it can also be seen that using metal sources with the same anion is more conducive to realizing the homogenization and homophase regeneration of the failed material.

Claims

1. A method for homogenizing and recycling the cathode material of waste lithium-ion batteries, characterized in that: The cathode material of the failed lithium-ion battery is subjected to high-energy ball milling and then classified by a liquid-phase cyclone force field to select the cathode material powder with a D90 of the micron level. The cathode material powder is first subjected to pre-oxidation calcination, and then the corresponding lithium source and transition metal source are supplemented according to the metal element ratio in the target recycled cathode material for secondary calcination, thus obtaining the recycled cathode material; The cathode material of the failed lithium-ion battery is derived from at least two of ternary cathode materials, lithium manganate materials, and lithium cobaltate materials; The D90 of the cathode material powder is between 0.3 μm and 1 μm; The conditions for the pre-oxidation calcination are: in an oxidizing atmosphere, at a temperature of 600 °C to 1200 °C, calcined for 0.5 h to 30 h.

2. A method for homogenizing and recycling the cathode material of a waste lithium-ion battery according to claim 1, characterized in that: The lithium source includes at least one of lithium carbonate, lithium hydroxide, and lithium nitrate; The transition metal source includes at least one of nickel source, cobalt source, manganese source, and iron source.

3. A method for homogenizing and recycling the cathode material of waste lithium-ion batteries according to claim 2, characterized in that: The lithium source and the transition metal source contain the same anion.

4. A method for homogenizing and recycling the cathode material of waste lithium-ion batteries according to claim 1, characterized in that: When the cathode material of the failed lithium-ion battery is derived from at least two of ternary cathode materials, lithium manganate materials, and lithium cobaltate materials, the conditions for the secondary calcination are: in an oxidizing atmosphere, first calcined at 350 °C to 450 °C for 3 h to 6 h, and then calcined at 800 °C to 1000 °C for 10 h to 16 h.

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