Direct single-crystal regeneration method for mixed waste ternary positive electrode material

Abstract

The invention discloses a direct single-crystal regeneration method for a mixed type waste ternary positive electrode material. The method comprises the following steps: mixing lithium salt with different types of waste ternary positive electrode materials in an oxygen atmosphere through a plasma ball mill to obtain a mixture, and sintering the mixture to obtain the regenerated single-crystal ternary positive electrode material. The mass ratio of the lithium salt to the waste ternary positive electrode material is (0.1-2.0): 1; the lithium salt contains lithium stearate. According to the method, different types of mixed waste ternary positive electrode materials can be subjected to direct single-crystal regeneration, the blank in the technical field of direct regeneration of the mixed waste ternary positive electrode materials is filled, the operation is simple, and the obtained regenerated positive electrode material has excellent specific discharge capacity and cycle retention rate, and is suitable for industrial production. The electrochemical cycle performance requirement of a commercial ternary positive electrode material is met, and the method is worthy of popularization and application.

Description

Technical Field

[0001] The present invention belongs to the technical field of recycling of waste cathode materials, and particularly relates to a method for directly single-crystallizing and regenerating a mixed waste ternary cathode material. Background Art

[0002] Lithium-ion batteries (LIBs) have advantages such as high energy density, high output voltage, and long service life, and are widely used in electric vehicles (EVs) and the energy storage industry. A large number of lithium-ion batteries will be retired after long-term recycling. Due to the lack of resources and the rising price of lithium-ion battery cathode materials, the recycling of waste cathode materials in waste lithium-ion batteries is very promising. Direct regeneration technology has been developed in the recycling of waste cathode materials due to its advantages such as short process, environmental protection, low energy consumption, and high added value. Traditional recycling methods for extracting valuable elements from waste LiNi x Co y Mn 1−x−y O 2 (NCM) cathode materials are limited by the difficulties of separation and purification and environmental pollution. The direct regeneration method can effectively avoid these problems. The research on the direct regeneration technology of waste LiNi x Co y Mn 1−x−y O 2 cathode materials focuses on repairing the compositional and structural defects of lithium-deficient cathode particles. However, the failure of waste ternary materials also includes other problems, such as particle fragmentation, surface layer structure damage, poor particle structure stability, etc. Existing direct regeneration methods, including solid-state reaction, hydrothermal treatment, and low-temperature eutectic regeneration methods, have solved the recycling problem of waste cathode materials with well-preserved layered structures. However, these methods cannot solve the problems of broken particles of waste ternary materials, limiting their application scenarios.

[0003] Generally, the ternary cathode material NCM is usually a spherical polycrystalline secondary particle formed by the aggregation of many primary nanoscale particles. One of the failure mechanisms of polycrystalline cathode materials is particle cleavage during long-term cycling, which is caused by the change in volume anisotropy of the primary particles during cycling. Single-crystalline NCM cathode materials have received extensive attention due to their excellent structural stability and good battery capacity retention, and are considered to have the application prospect of manufacturing mechanically reliable solid-state batteries. Compared with polycrystalline materials, single-crystalline materials have no grain boundaries in the particles, showing an overall stable structure and a continuous conductive network, which can effectively inhibit the crack problem of the NCM cathode. At the same time, single-crystalline NCM cathode materials show many advantages, including high tap density and mechanical strength, smooth single-crystalline particle surface, small volume expansion, etc., which are beneficial to increasing the volumetric energy density of the battery, full contact and coating with conductive carbon materials, and improving the safety of the battery.

[0004] The ternary cathode materials involved in the market mainly include three series of nickel cobalt manganese materials (LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 ), five series of nickel cobalt manganese materials (LiNi 0.5 Co 0.2 Mn 0.3 O 2 ), and eight series of nickel cobalt manganese materials (LiNi 0.8 Co 0.1 Mn 0.1 O 2 ). At present, the regeneration methods of waste cathode materials can generally only be applied to a single type of waste ternary cathode material, and it is impossible to directly regenerate mixed waste ternary cathode materials.

[0005] The present invention aims to provide a method for directly regenerating mixed waste ternary cathode materials into single crystals. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for directly regenerating mixed waste ternary cathode materials into single crystals.

[0007] The purpose of the present invention is achieved as follows: A method for directly regenerating mixed waste ternary cathode materials into single crystals is to ball-mill and mix a lithium salt and waste ternary cathode materials in an oxygen atmosphere through a plasma ball mill to obtain a mixed material, and then sinter the mixed material to obtain a regenerated single-crystal ternary cathode material; The mass ratio of the lithium salt to the waste ternary cathode materials is 0.1 - 2.0:1; The lithium salt contains lithium stearate; The beneficial effects of the present invention are as follows: The method of the present invention can directly regenerate mixed different types of waste ternary cathode materials into single crystals, filling the blank in the field of direct regeneration technology for mixed waste ternary cathode materials. Moreover, the operation is simple, and the obtained regenerated cathode material has excellent discharge specific capacity and cycle retention rate, meeting the electrochemical cycle performance requirements of commercial ternary cathode materials, and is worthy of popularization and application. Brief Description of the Drawings

[0008] Figure 1 It is the SEM image of waste three-series nickel cobalt manganese materials; Figure 2 It is the SEM image of waste five-series nickel cobalt manganese materials; Figure 3 It is the SEM image of waste eight-series nickel cobalt manganese materials; Figure 4 It is the SEM image of the mixed material obtained after ball-milling the waste mixed cathode materials and the lithium salt in Example 1; Figure 5 SEM image of the mixture after water washing in Example 1; Figure 6 SEM image of the mixture after tempering in Example 1; Figure 7 XRD patterns of waste ternary nickel cobalt manganese materials, waste quinary nickel cobalt manganese materials, and waste octanary nickel cobalt manganese materials; Figure 8 XRD patterns of the waste mixed cathode materials and lithium salts after ball milling in Examples 1-4; Figure 9 XRD patterns of the mixtures after roasting in Examples 1-4; Figure 10 XRD patterns of the mixtures after water washing in Examples 1-4; Figure 11 XRD patterns of the mixtures after tempering in Examples 1-4; Figure 12 Electrochemical performance graphs of the coin cells prepared from the regenerated ternary cathode materials prepared in Example 1, waste mixed ternary materials, and ternary cathode materials prepared in Comparative Example 1 at different rates; Figure 13 Electrochemical cycling performance graphs of the coin cells prepared from the regenerated ternary cathode materials prepared in Example 1 and Example 2, three different waste ternary materials, and ternary cathode materials prepared in Comparative Example 1 at 1C rate. Detailed implementation manners

[0009] The present invention will be further described in detail below with reference to the drawings and examples, but the present invention is not limited in any way. Any transformation or improvement based on the teachings of the present invention falls within the protection scope of the present invention.

[0010] A method for directly single-crystallizing and regenerating a hybrid waste ternary cathode material of the present invention is to ball-mill and mix a lithium salt and a waste ternary cathode material in an oxygen atmosphere through a plasma ball mill to obtain a mixture, and then sinter the mixture to obtain a regenerated single-crystalline ternary cathode material; The mass ratio of the lithium salt to the waste ternary cathode material is 0.1-2.0:1; The lithium salt contains lithium stearate; The ball-milling and mixing time each time is 20 min, and the interval time is 10 min; the number of ball-milling times is 2-3 times; The working parameters of the plasma ball mill are as follows: the rotation speed is 1300 r / min, the power is 1000 W, the frequency is 10 Hz, the current is 100 mA, and the voltage is 30 kV.

[0011] The lithium salt further includes lithium sulfate and / or lithium nitrate.

[0012] The sintering regime is as follows: The mixture is heated in an oxygen atmosphere at a temperature of 50°C at a heating rate of 2 - 10°C / min to 900°C and held for 4 - 10 h, and after natural cooling, it is washed with deionized water and then tempered to obtain the regenerated single-crystal ternary cathode material; the tempering regime is: at a temperature of 50°C at a heating rate of 3 - 5°C / min to 500 - 700°C and held for 4 h.

[0013] The sintering regime is as follows: The mixture is heated in an oxygen atmosphere at a temperature of 50°C at a heating rate of 3°C / min to 500 - 700°C and held for 4 - 10 h, then at a heating rate of 2°C / min to 900 - 1000°C and held for 6 - 10 h, and after natural cooling, it is washed with deionized water and then tempered to obtain the regenerated single-crystal ternary cathode material; the tempering regime is: at a temperature of 50°C at a heating rate of 3 - 5°C / min to 500 - 700°C and held for 4 h.

[0014] The application of the method in the regeneration of waste ternary cathode materials is characterized in that the waste cathode material is a single type of waste cathode material or a mixed waste cathode material of two or more types.

[0015] Example 1 4 g of lithium stearate, 3 g of lithium sulfate, 3 g of lithium nitrate, 11 g of waste ternary nickel cobalt manganese material (LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 ), 11 g of waste quinary nickel cobalt manganese material (LiNi 0.5 Co 0.2 Mn 0.3 O 2 ) and 11 g of waste octal nickel cobalt manganese material (LiNi 0.8 Co 0.1 Mn 0.1 O 2 ) of six powder materials are ball-milled and mixed in a plasma ball mill to obtain a uniformly mixed mixture ( Figure 4 and Figure 8 ). The working conditions of the plasma ball mill are: in an oxygen atmosphere, the rotation speed is 1300 r / min, the power is 1000 W, the frequency is 10 Hz, the current is 100 mA, and the voltage is 30 kV; one working cycle is 20 min of ball milling and 10 min of stopping, and a total of 3 cycles are worked. It can be seen from Figure 1 that the spherical particles of the waste LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 cathode material are damaged, with a large amount of impurities attached to the surface, and the polycrystalline and single-crystal morphologies of the waste ternary nickel cobalt manganese materials in the market are not uniform, and some particles are agglomerated. FromFigure 2 It can be seen that the used LiNi 0.5 Co 0.2 Mn 0.3 O 2 The polycrystalline and single-crystalline morphologies of the cathode material are not uniform, and a large amount of impurities adhere to the particle surface. It can be seen from the low-magnification images that the particle size of the overall particles is significantly uneven and agglomeration is obvious. From Figure 3 It can be seen that the used LiNi 0.8 Co 0.1 Mn 0.1 O 2 The cathode material is distributed in polycrystalline spherical shapes, and obvious flocculent substances adhere to the particle surface. Some spherical particles have obvious cracks. Local agglomeration and partial particle fragmentation can be observed from the low-magnification images.

[0016] The mixed material is sintered in an oxygen atmosphere at 50°C. The sintering regime is as follows: heating at a rate of 3°C / min to 500°C and holding for 4 h, then heating at a rate of 2°C / min to 900°C and holding for 10 h, and then naturally cooling ( Figure 9 ). After taking out the sintered material and washing it with deionized water ( Figure 5 and Figure 10 ), then tempering (the tempering regime is: heating at a rate of 3°C / min to 500°C and holding for 4 h at 50°C). Then the regenerated single-crystalline nickel cobalt manganese ternary material can be obtained, named CL. This regenerated cathode material has a layered structure ( Figure 11 ), which is completely different from the spherical irregular particle morphology of the original used material. It has a single-crystalline morphology, uniform particle size distribution, dispersed particles, and no agglomeration phenomenon ( Figure 6 ).

[0017] Example 2 Mix 15 g of lithium stearate, 10 g of used ternary nickel cobalt manganese material (LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 ), 10 g of used quinary nickel cobalt manganese material (LiNi 0.5 Co 0.2 Mn 0.3 O 2 ), and 10 g of used octanary nickel cobalt manganese material (LiNi 0.8 Co 0.1 Mn 0.1 O2). Ball-mill and mix the four powder materials in a plasma ball mill to obtain a uniformly mixed material ( Figure 8). The working conditions of the plasma ball mill are as follows: in an oxygen atmosphere, the rotation speed is 1300 r / min, the power is 1000 W, the frequency is 10 Hz, the current is 100 mA, and the voltage is 30 kV; a working cycle is 20 minutes of ball milling followed by 10 minutes of stopping, and it works for a total of 3 cycles.

[0018] The mixed material is sintered in an oxygen atmosphere at a temperature of 50 °C. The sintering regime is as follows: heating at a rate of 3 °C / min to 500 °C and holding for 4 h, then heating at a rate of 2 °C / min to 900 °C and holding for 10 h, and then naturally cooling ( Figure 9 ). After taking out the sintered material and washing it with deionized water ( Figure 10 ), then tempering can obtain the regenerated single-crystal nickel cobalt manganese ternary material ( Figure 11 ), named CL. The tempering regime is: heating at a rate of 3 °C / min to 500 °C and holding for 4 h at a temperature of 50 °C.

[0019] Example 3 12 g of lithium stearate, 9 g of lithium sulfate, 9 g of lithium nitrate, 10 g of waste ternary nickel cobalt manganese material (LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 ), 10 g of waste quinary nickel cobalt manganese material (LiNi 0.5 Co 0.2 Mn 0.3 O 2 ), and 10 g of waste octal nickel cobalt manganese material (LiNi 0.8 Co 0.1 Mn 0.1 O 2 ) are ball-milled and mixed in a plasma ball mill to obtain a uniformly mixed material ( Figure 8 ). The working conditions of the plasma ball mill are as follows: in an oxygen atmosphere, the rotation speed is 1300 r / min, the power is 1000 W, the frequency is 10 Hz, the current is 100 mA, and the voltage is 30 kV; a working cycle is 20 minutes of ball milling followed by 10 minutes of stopping, and it works for a total of 3 cycles.

[0020] The mixed material is sintered in an oxygen atmosphere at a temperature of 50 °C. The sintering regime is as follows: heating at a rate of 2 °C / min to 900 °C and holding for 10 h, and then naturally cooling ( Figure 9 ). After taking out the sintered material and washing it with deionized water ( Figure 10 ), then tempering can obtain the regenerated single-crystal nickel cobalt manganese ternary material ( Figure 11 ), named CL. The tempering regime is: heating at a rate of 3 °C / min to 500 °C and holding for 4 h at a temperature of 50 °C.

[0021] Example 4 Mix 10 g of lithium stearate, 10 g of waste ternary nickel cobalt manganese material (LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 ), 10 g of waste quinary nickel cobalt manganese material (LiNi 0.5 Co 0.2 Mn 0.3 O 2 ), and 10 g of waste octonary nickel cobalt manganese material (LiNi 0.8 Co 0.1 Mn 0.1 O 2 ) in a planetary ball mill with plasma to obtain a uniformly mixed mixture ( Figure 8 ). The working conditions of the planetary ball mill with plasma are as follows: in an oxygen atmosphere, the rotation speed is 1300 r / min, the power is 1000 W, the frequency is 10 Hz, the current is 100 mA, and the voltage is 30 kV; one working cycle is 20 min of ball milling followed by 10 min of stopping, and a total of 3 cycles are worked.

[0022] Sinter the mixture in an oxygen atmosphere at a temperature of 50 °C. The sintering regime is: heat up to 900 °C at a heating rate of 3 °C / min and hold for 10 h, then cool naturally ( Figure 9 ). Take out the sintered material, wash it with deionized water ( Figure 10 ), and then temper it to obtain the regenerated single-crystal nickel cobalt manganese ternary material ( Figure 11 ), named CL. The tempering regime is: heat up to 700 °C at a heating rate of 5 °C / min at a temperature of 50 °C and hold for 4 h.

[0023] Example 5 Mix 1.2 g of lithium stearate, 0.9 g of lithium sulfate, 0.9 g of lithium nitrate, 10 g of waste ternary nickel cobalt manganese material (LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 ), 10 g of waste quinary nickel cobalt manganese material (LiNi 0.5 Co 0.2 Mn 0.3 O 2 ), and 10 g of waste octonary nickel cobalt manganese material (LiNi 0.8 Co 0.1 Mn 0.1 O 2)Six kinds of powder materials are ball-milled and mixed in a plasma ball mill to obtain a uniformly mixed mixture. The working conditions of the plasma ball mill are as follows: in an argon atmosphere, the rotation speed is 1300 r / min, the power is 1000 W, the frequency is 10 Hz, the current is 100 mA, and the voltage is 30 kV; a working cycle is 20 minutes of ball milling followed by 10 minutes of stopping, and a total of 2 cycles are worked.

[0024] The mixture is sintered at 50 °C in an oxygen atmosphere. The sintering regime is as follows: heating at a rate of 3 °C / min to 900 °C and holding for 10 h, then naturally cooling. After taking out the sintered material and washing it with deionized water, tempering can obtain the regenerated single-crystal nickel cobalt manganese ternary material, named CL. The tempering regime is as follows: heating at a rate of 5 °C / min to 700 °C at 50 °C and holding for 4 h.

[0025] Example 6 Add 4 g of lithium stearate and 3 g of lithium nitrate in a mass ratio of 40:30, 10 g of waste ternary nickel cobalt manganese material (LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 ), 10 g of waste quinary nickel cobalt manganese material (LiNi 0.5 Co 0.2 Mn 0.3 O 2 ), and 10 g of waste octonary nickel cobalt manganese material (LiNi 0.8 Co 0.1 Mn 0.1 O2) are added in a mass ratio of 1:1:1. Six kinds of powder materials are ball-milled and mixed in a plasma ball mill to obtain a uniformly mixed mixture. The working conditions of the plasma ball mill are as follows: in an oxygen atmosphere, the rotation speed is 1300 r / min, the power is 1000 W, the frequency is 10 Hz, the current is 100 mA, and the voltage is 30 kV; a working cycle is 20 minutes of ball milling followed by 10 minutes of stopping, and a total of 3 cycles are worked.

[0026] The mixture is sintered at 50 °C in an oxygen atmosphere. The sintering regime is as follows: heating at a rate of 3 °C / min to 700 °C and holding for 4 h, then heating at a rate of 2 °C / min to 1000 °C and holding for 6 h, then naturally cooling. After taking out the sintered material and washing it with deionized water, tempering can obtain the regenerated single-crystal nickel cobalt manganese ternary material. The tempering regime is as follows: heating at a rate of 3 °C / min to 500 °C at 50 °C and holding for 4 h.

[0027] Comparative Example 1 Add 4 g of lithium carbonate, 3 g of lithium sulfate and 3 g of lithium nitrate in a mass ratio of 40:30:30, 11 g of waste ternary nickel cobalt manganese material (LiNi1 / 3 Co 1 / 3 Mn 1 / 3 O 2 ), 11 g of waste five - series nickel - cobalt - manganese material (LiNi 0.5 Co 0.2 Mn 0.3 O 2 ) and 11 g of waste eight - series nickel - cobalt - manganese material (LiNi 0.8 Co 0.1 Mn 0.1 O2) are added in a mass ratio of 1:1:1. The six powder materials are ball - milled and mixed in a plasma ball - mill to obtain a uniformly mixed mixture ( Figure 8 ). The working conditions of the plasma ball - mill are as follows: in an oxygen atmosphere, the rotation speed is 1300 r / min, the power is 1000 W, the frequency is 10 Hz, the current is 100 mA, and the voltage is 30 kV; one working cycle is 20 min of ball - milling followed by 10 min of stopping, and a total of 3 cycles are worked.

[0028] The mixture is sintered in an oxygen atmosphere at a temperature of 50 °C. The sintering regime is: heating at a rate of 3 °C / min to 500 °C and holding for 4 h, then heating at a rate of 2 °C / min to 900 °C and holding for 10 h, and then naturally cooling ( Figure 9 ). After taking out the sintered material and washing it with deionized water ( Figure 10 ), it is tempered to obtain the recycled single - crystal nickel - cobalt - manganese ternary material ( Figure 11 ). The tempering regime is: heating at a rate of 3 °C / min to 500 °C and holding for 4 h at a temperature of 50 °C.

[0029] Comparative Example 2 4 g of lithium carbonate, 3 g of lithium sulfate and 3 g of lithium hydroxide are added in a mass ratio of 40:30:30, 11 g of waste three - series nickel - cobalt - manganese material (LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 ), 11 g of waste five - series nickel - cobalt - manganese material (LiNi 0.5 Co 0.2 Mn 0.3 O 2 ) and 11 g of waste eight - series nickel - cobalt - manganese material (LiNi 0.8 Co 0.1 Mn 0.1O2) is added in a mass ratio of 1:1:1, and the six powder materials are ball-milled and mixed in a plasma ball mill to obtain a uniformly mixed mixture. The working conditions of the plasma ball mill are as follows: in an oxygen atmosphere, the rotation speed is 1300 r / min, the power is 1000 W, the frequency is 10 Hz, the current is 100 mA, and the voltage is 30 kV; a working cycle is 20 minutes of ball milling followed by 10 minutes of stopping, and a total of 3 cycles are worked.

[0030] The mixture is sintered in an oxygen atmosphere at a temperature of 50 °C, and the sintering regime is as follows: heating at a rate of 3 °C / min to 500 °C and holding for 4 h, then heating at a rate of 2 °C / min to 900 °C and holding for 10 h, and then naturally cooling. After taking out the sintered material and washing it with deionized water, it is tempered to obtain the regenerated single-crystal nickel cobalt manganese ternary material. The tempering regime is: heating at a rate of 3 °C / min to 500 °C and holding for 4 h at a temperature of 50 °C.

[0031] Analysis of the XRD patterns of the cathode materials obtained in Examples 1-4 and Comparative Example 1; Figure 7 It shows that impurity peaks (20° - 40°) have appeared in the waste ternary cathode material, which is caused by uneven element content and damaged layered structure. From Figure 8-9 it can be seen that there are obvious differences in the ratios of the 003 characteristic peak (near 18°) and 104 characteristic peak (near 45°) of the ternary material obtained after ball milling and roasting. From the ratio of the two characteristic peaks of Comparative Example 1, the layered structure cannot be well repaired, and the splitting morphology of the splitting peak near 65° is damaged, indicating that the ordered layered structure of Comparative Example 1 cannot be restored.

[0032] From Figure 11 it can be seen that the ratio of the 003 characteristic peak (near 18°) and 104 characteristic peak (near 45°) of the ternary material is closely related to its layered structure. The ratio of the two characteristic peaks of Comparative Example 1 indicates that a ternary regenerated material with a layered structure cannot be obtained in this lithium salt system, while layered-structured ternary regenerated materials can be obtained in Examples 1-4.

[0033] Test Example 1 1. The regenerated single-crystal nickel cobalt manganese ternary materials prepared in Example 1 and Comparative Example 1, and the mixture of the three waste cathode materials in Example 1 are respectively ground evenly with acetylene black in a mortar, and NMP dissolved with PVDF is added, and stirred until a slurry without particles is obtained. The mass ratio of the regenerated lithium iron phosphate material: acetylene black: PVDF is 8:1:1. The uniform slurry is coated on the aluminum foil, and then vacuum dried overnight at 80 °C. The dried electrode sheet is cut into circular pieces with a diameter of 12 mm for assembling coin cells (type: CR2032), and the average mass loading is about 5.8 mg / cm 2。The lithium metal chip is used as the anode of the half-cell structure, and the electrolyte is composed of LiPF6, FEC, DMC, and DEC in proportion. The obtained coin cells can be tested at different rates to test the rate performance, discharge specific capacity, and cycle retention rate. The results are as Figure 12 shown.

[0034] Result analysis: From Figure 12 it can be seen that the regenerated single-crystalline ternary material obtained in Example 1 has excellent rate performance, discharge specific capacity, and cycle retention rate, which already meet the electrochemical performance requirements of commercial ternary cathode materials.

[0035] 2. The regenerated single-crystalline nickel cobalt manganese ternary materials prepared in Examples 1-2 and Comparative Examples 1-2 and the three kinds of waste cathode materials in Example 1 are respectively made into coin cells, and the cycle performance is tested at a rate of 1C.

[0036] Result analysis, from Figure 13 it can be seen that compared with Comparative Example 1 and the original waste cathode material, the battery prepared with the regenerated single-crystalline nickel cobalt manganese ternary material prepared in Examples 1-2 has excellent cycle performance and meets the electrochemical cycle performance requirements of commercial ternary cathode materials.

Claims

1. A method for direct single crystal regeneration of mixed waste ternary cathode materials, characterized in that: The lithium salt and the waste ternary cathode material are ball-milled in an oxygen atmosphere by a plasma ball mill to obtain a mixture, and then the mixture is sintered to obtain a regenerated single crystal ternary cathode material; The mass ratio of the lithium salt to the waste ternary positive electrode material is 0.1-2.0:1; The lithium salt contains lithium stearate.

2. The method for direct single crystal regeneration of mixed waste ternary cathode materials according to claim 1, characterized in that: The mixing time of each ball milling is 20 minutes, and the interval time is 10 minutes; the number of ball milling is 2-3 times; The operating parameters of the plasma ball mill are as follows: speed is 1300 r / min, power is 1000 W, frequency is 10 Hz, current is 100 mA, and voltage is 30 kV.

3. The method for direct single crystal regeneration of mixed waste ternary cathode materials according to claim 1, characterized in that: The lithium salt also includes lithium sulfate and / or lithium nitrate.

4. The method for direct single crystal regeneration of mixed waste ternary cathode materials according to claim 1, characterized in that: The sintering system is as follows: the mixture is heated to 900°C at a rate of 2-10°C / min at 50°C in an oxygen atmosphere and kept warm for 4-10 hours, and after natural cooling, it is washed with deionized water and tempered to obtain a regenerated single crystal ternary positive electrode material; the tempering system is as follows: the mixture is heated to 500-700°C at a rate of 3-5°C / min at 50°C and kept warm for 4 hours.

5. The method for direct single crystal regeneration of mixed waste ternary cathode materials according to claim 1, characterized in that: The sintering system is as follows: the mixture is heated to 500-700°C at a rate of 3°C / min at 50°C in an oxygen atmosphere and kept warm for 4-10h, then heated to 900-1000°C at a rate of 2°C / min and kept warm for 6-10h, and after natural cooling, it is washed with deionized water and tempered to obtain a regenerated single crystal ternary positive electrode material; the tempering system is as follows: the mixture is heated to 500-700°C at a rate of 3-5°C / min at 50°C and kept warm for 4h.

6. Application of the method of claim 1 in the regeneration of waste ternary cathode materials, characterized in that: The waste positive electrode material is a single type of waste positive electrode material or a mixed type of two or more types of waste positive electrode materials.

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