A doped repaired regenerated lithium nickel cobalt manganese oxide ternary material, a preparation method thereof and use thereof

Abstract

The application provides a doped and repaired regenerated lithium nickel cobalt manganese oxide ternary material, a preparation method and application thereof, and belongs to the field of resource recycling science and engineering. The preparation method comprises the following steps: sequentially performing alkali washing and impurity removal and low-temperature pre-burning on waste lithium nickel cobalt manganese oxide material to obtain an activated material; mixing the activated material with a first lithium source, and performing one-time lithium supplement sintering to obtain one-time lithium supplement regenerated material; mixing the one-time lithium supplement regenerated material with a second lithium source and a lanthanide compound, and performing secondary sintering to obtain the doped and repaired regenerated lithium nickel cobalt manganese oxide ternary material. The application adopts a synergistic repair process of "alkali washing and impurity removal-low-temperature pre-burning-step-by-step lithium supplement-lanthanide element doping", does not need to use corrosive reagents and complex separation steps, and has the advantages of simple process, low energy consumption and green environmental protection. The obtained regenerated material restores the layered crystal structure, and when used as a lithium ion battery positive electrode material, has excellent cycle stability and rate performance.

Description

Technical Field

[0001] This invention belongs to the field of resource recycling science and engineering, specifically relating to a doped repair and regeneration lithium nickel cobalt manganese oxide ternary material, its preparation method, and its applications. Background Technology

[0002] Lithium nickel cobalt manganese oxide (LiCO) ternary materials have become the mainstream cathode material for power batteries due to their high energy density, excellent cycle performance, and good safety performance, and are widely used in new energy vehicles and energy storage systems. With the rapid development of the new energy vehicle industry, the installed capacity of ternary lithium batteries continues to climb, and a large-scale retirement wave is expected in the coming years. Retired ternary lithium batteries contain a large amount of valuable metals such as nickel, cobalt, manganese, and lithium, and the cathode material itself still maintains the layered structure, providing a material basis for direct repair and regeneration. However, waste ternary materials undergo complex structural degradation during long-term cycling, including lattice lithium loss, mixing of lithium ions with transition metal ions, microcrack formation, and surface by-product deposition, leading to a severe decline in their electrochemical performance. Traditional pyrometallurgical or hydrometallurgical recycling methods not only destroy the original crystal structure, causing huge consumption of energy and chemical reagents, but also generate secondary pollution; while simple lithium replenishment regeneration cannot repair deep-seated crystal structure defects and interface damage, and the electrochemical performance of the regenerated materials often fails to meet practical application requirements. Therefore, developing recycling technologies for waste ternary materials that can simultaneously achieve structural repair and performance improvement is of great practical significance for realizing the green and sustainable development of the power battery industry.

[0003] Currently, recycling technologies for waste nickel-cobalt-manganese lithium ternary materials are mainly divided into three categories: pyrometallurgy, hydrometallurgy, and direct recycling. Pyrometallurgy recovers valuable metals through high-temperature smelting at 1200–1600℃, achieving a high overall metal recovery rate and wide applicability. However, it is an energy-intensive process that generates harmful pollutants such as fluorides, and lithium is easily lost through volatilization. The recovered products are mostly alloys, which cannot be directly used as cathode materials for lithium-ion batteries and require subsequent cumbersome purification processes. Hydrometallurgy uses chemical solvents to leach valuable metals from the battery, followed by separation and purification through extraction, precipitation, and other processes. While it can achieve stepwise metal recovery, the process route is lengthy, and it is difficult to separate metals with similar properties such as nickel, cobalt, and manganese. It also generates a large amount of waste liquid and residue, posing a serious risk of secondary pollution, and consumes a large amount of reagents, making it uneconomical. Both pyrometallurgical and hydrometallurgical processes belong to the indirect recycling model of "dismantling-extraction-reconstruction," which fails to preserve the original crystal structure of the cathode material, resulting in low recovery efficiency of valuable metals and low energy utilization. Direct regeneration technology repairs the crystal structure and electrochemical performance of waste cathode materials through simple physical or chemical means, preserving the original layered structure without the need for complex metal separation and purification. It is an energy-saving and efficient recycling method and has become a current research hotspot. However, existing direct regeneration technologies for ternary materials still have many bottlenecks, such as the difficulty in effectively filling microcracks in waste material particles and repairing lattice defects. The lithium replenishment process is prone to uneven lithium content, and the recycled materials have poor interfacial stability, rate performance, and cycle life. Mature industrial application technology has not yet been formed, and it cannot meet the quality requirements of the ternary battery industry for recycled cathode materials.

[0004] To overcome the aforementioned bottlenecks, a direct repair technology combining doping modification and lithium replenishment regeneration has emerged. This technology compensates for lithium loss in waste materials by replenishing lithium, while introducing doping elements to regulate the crystal structure and electronic conduction characteristics of the materials. It can both preserve the initial layered crystal structure of lithium nickel cobalt manganese oxide ternary materials and achieve the repair and improvement of the electrochemical performance of the materials, effectively overcoming the performance shortcomings of traditional direct regeneration technologies. However, this type of technology still faces many problems that need to be solved in practical applications. The core obstacle to its large-scale development lies in achieving a balance in the following three aspects: (1) efficiently repairing lattice defects and particle morphology to restore the intrinsic electrochemical performance of the materials; (2) accurately controlling the content and existence form of doping elements to improve the cycle stability and rate performance of the materials; (3) simplifying process steps, reducing energy consumption, and achieving green and economical regeneration processes.

[0005] Reference 1 (Advanced Energy Materials, 2024, 14, 2402918) discloses a method for upgrading and recycling retired nickel-rich cathode material (NCM811) using lanthanum doping and a LiLaO2 coating layer. This technology utilizes the existing lithium vacancies in the retired cathode material to reduce the diffusion barrier of lanthanum, thereby achieving passive filling of lanthanum in the crystal lattice. However, this technology has the following shortcomings: (1) The process needs to be carried out under strict high vacuum or protective atmosphere, which requires high-end equipment and consumes a lot of energy, making it unsuitable for large-scale industrial application; (2) This method is highly dependent on the initial distribution state of lithium vacancies in the retired material, and has limited repair effect on waste materials with insufficient or unevenly distributed lithium vacancies, resulting in poor universality; (3) The passive filling doping method makes it difficult to achieve precise control over the existence form of doping elements, the charge transfer impedance of the recycled material is still relatively high, and the interfacial lithium-ion transport dynamics need to be further improved. Therefore, developing a simple, energy-efficient, universally applicable, and highly effective recycling technology for waste nickel-cobalt-manganese lithium ternary materials is of significant industrial application value for promoting resource recycling and green development in the ternary lithium battery industry. Summary of the Invention

[0006] In view of the problems existing in the recycling technology of waste nickel cobalt manganese ternary materials, such as damage to crystal structure, high energy consumption and poor repair effect, the purpose of this invention is to provide a doped repair and regeneration nickel cobalt manganese ternary material, its preparation method and application.

[0007] To achieve the above objectives, the specific technical solution adopted by the present invention is as follows: This invention provides a method for preparing doped, repaired, and regenerated lithium nickel cobalt manganese oxide ternary materials, the preparation method comprising the following steps: S1. Alkali washing and pre-sintering step: Place the lithium nickel cobalt manganese oxide material in an alkaline solution and stir, wash and dry, and pre-sinter to obtain activated lithium nickel cobalt manganese oxide ternary material. S2, First lithium replenishment step: The activated lithium nickel cobalt manganese oxide ternary material is mixed with the first lithium source, ground under infrared lamp irradiation, sintered for the first time, washed and dried to obtain lithium nickel cobalt manganese oxide ternary material regenerated by first lithium replenishment. S3. Lanthanide doping repair and regeneration step: The nickel cobalt manganese oxide ternary material regenerated by the first lithium replenishment is mixed with a second lithium source and lanthanide compounds, ground under infrared lamp irradiation, and sintered for the second time to obtain the doped repair and regenerated nickel cobalt manganese oxide ternary material.

[0008] Further, the alkaline solution is selected from at least one of sodium hydroxide solution, potassium hydroxide solution, barium hydroxide solution or calcium hydroxide solution, and the concentration of the alkaline solution is 0.5 mol / L to 2.0 mol / L; preferably, the concentration of the alkaline solution is 1.0 mol / L.

[0009] Furthermore, the pre-sintering conditions are as follows: heating to 350℃~450℃ at a heating rate of 2℃ / min~10℃ / min and holding at that temperature for 1 h~3 h.

[0010] Furthermore, the first lithium source and the second lithium source are each independently selected from at least one of lithium hydroxide, lithium carbonate, lithium nitrate, lithium acetate, lithium benzoate, and lithium oxalate.

[0011] Further, in step S2, the molar ratio of the activated lithium nickel cobalt manganese oxide ternary material to the first lithium source is 1:(0.3~1.1); preferably, the molar ratio of the activated lithium nickel cobalt manganese oxide ternary material to the first lithium source is 1:1; In step S3, the molar ratio of the lithium nickel cobalt manganese oxide ternary material regenerated by the first lithium replenishment to the second lithium source is 1:(0.3~1.1); preferably, the molar ratio of the lithium nickel cobalt manganese oxide ternary material regenerated by the first lithium replenishment to the second lithium source is 1:1.

[0012] Further, the lanthanide compound is selected from at least one oxide, nitrate, or chloride of lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, erbium, thulium, ytterbium, and lutetium; the doping amount of the lanthanide compound is 1 wt.% to 6 wt.% of the total mass of the lithium nickel cobalt manganese oxide ternary material; preferably, the doping amount is 2 wt.% to 3 wt.%.

[0013] Furthermore, the temperature of the first sintering is 250℃~350℃, and the temperature of the second sintering is 750℃~950℃.

[0014] The present invention also provides a doped, repaired and regenerated lithium nickel cobalt manganese oxide ternary material, which is prepared by the aforementioned preparation method.

[0015] Furthermore, in the material, lanthanide elements replace some Ni, Co, and Mn lattice sites in the form of doped atoms, or occupy lithium vacancies, or form lanthanide oxide dispersed phases distributed on the particle surface; the microscopic particle cracks of the material are filled, and a dense doped modified layer is formed on the particle surface.

[0016] The doped repair and regeneration lithium nickel cobalt manganese oxide ternary material prepared according to the present invention can restore the initial layered structure of lithium nickel cobalt manganese oxide ternary material, effectively fill the microcracks of micro particles, form stable connections between broken particles, form a dense doped modification layer on the particle surface, and construct an overall bulk phase structure with complete crystal form and stable interface.

[0017] The present invention also provides the use of the aforementioned doped, repaired, and regenerated lithium nickel cobalt manganese oxide ternary material in the preparation of lithium-ion battery cathode materials.

[0018] The doped and repaired regenerated nickel-cobalt-manganese lithium ternary material of the present invention is used to prepare regenerated ternary lithium batteries. Preferably, when assembling ternary lithium-ion coin cells, the initial discharge specific capacity at 0.5 C is not less than 140 mAh / g; after 200 charge-discharge cycles, its coulombic efficiency is not less than 95% and its specific capacity is not less than 130 mAh / g.

[0019] Compared with the prior art, the present invention has achieved the following beneficial effects: (1) The preparation method of the doped repair and regenerated nickel cobalt manganese ternary material involved in this invention adopts a synergistic repair process of "alkali washing and impurity removal - low temperature pre-calcination - step-by-step lithium replenishment - lanthanide element doping". Through the organic combination of step-by-step lithium replenishment and high temperature lanthanide doping, the repair of the crystal structure of the waste ternary material and the improvement of its electrochemical performance are realized simultaneously. This avoids the damage to the material structure caused by traditional pyrometallurgical / hydrometallurgical processes and significantly reduces energy consumption and environmental pollution.

[0020] (2) The preparation method of the doped repair and regenerated lithium nickel cobalt manganese oxide ternary material involved in this invention adopts alkaline solution pretreatment to effectively remove aluminum foil residue, binder and organic impurities on the surface of waste ternary material. Low temperature pre-calcination at 400℃ can decompose residual organic matter and restore the material to its initial layered structure activity, providing a clean and activated base material for subsequent lithium replenishment and regeneration and doping repair, effectively improving the structural uniformity of the regenerated material.

[0021] (3) The preparation method of the doped repair regenerated lithium nickel cobalt manganese oxide ternary material involved in this invention uses infrared lamp irradiation to assist grinding and low temperature pre-sintering at 300℃ to achieve the initial embedding and uniform dispersion of lithium source, effectively repairing the lithium deficiency in the lattice; then, lanthanide element doping is carried out at a high temperature of 850℃. Lanthanide ions have a large radius, and after doping, they can effectively increase the interlayer spacing of transition metals, promote lithium ion transport, and suppress cation mixing and phase transition, significantly improving the structural stability of the material.

[0022] (4) The preparation method of the doped repair and regenerated nickel cobalt manganese ternary material involved in this invention involves lanthanide elements replacing part of the Ni, Co, and Mn lattice sites, occupying lithium vacancies, or forming lanthanide oxide dispersed phases distributed on the particle surface in the form of doped atoms. On the one hand, it stabilizes the layered crystal structure, and on the other hand, it constructs a dense surface doped modification layer, effectively suppressing the interfacial side reactions between the electrolyte and the cathode material, and significantly improving the cycle stability and rate performance of the material.

[0023] (5) The preparation method of the doped repair and regenerated nickel cobalt manganese ternary material involved in this invention is simple, easy to operate and cost controllable. It does not require the use of highly corrosive acid and alkali reagents and complex separation and purification steps, and realizes the green and efficient regeneration of waste ternary materials. It is expected to alleviate the problem of metal resource shortage caused by the rapid development of the lithium battery industry, and also reduce the environmental pollution of retired lithium batteries, providing technical support for the sustainable development of the power battery industry.

[0024] (6) Compared with the lanthanum doping repair technology reported in Reference 1 (Advanced Energy Materials, 2024, 14, 2402918), the present invention adopts a synergistic process of "alkali washing to remove impurities - low-temperature pre-calcination - stepwise lithium replenishment - lanthanide element doping", which can be completed in an atmospheric pressure air atmosphere. The lithium replenishment temperature is only 300℃, and the process is simpler and has lower energy consumption. The 5C rate capacity of the recycled material of the present invention exceeds 100 mAh / g, and the charge transfer impedance can be as low as 107.43 Ω, both of which are better than the similar indicators reported in Reference 1 (5C rate capacity not specified, impedance about 156 Ω). In addition, the method of the present invention has greater universality and is not limited to ternary materials with specific compositions. It is applicable to various types of decommissioned nickel-cobalt-manganese lithium oxide materials.

[0025] Obviously, based on the above description of the present invention, and according to common technical knowledge and conventional methods in the field, various other modifications, substitutions or alterations can be made without departing from the basic technical concept of the present invention.

[0026] The following detailed embodiments further illustrate the above-described content of the present invention. However, this should not be construed as limiting the scope of the present invention to the following embodiments. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention. Attached Figure Description

[0027] Figure 1 This is a microscopic morphology image of the doped, repaired, and regenerated lithium nickel cobalt manganese oxide ternary material prepared in Example 1 of the present invention.

[0028] Figure 2The graph shows a comparison of the cycle performance of the doped and regenerated lithium nickel cobalt manganese oxide ternary material prepared in Example 2 of this invention and the unregenerated lithium nickel cobalt manganese oxide ternary material when used as the positive electrode of a lithium-ion battery.

[0029] Figure 3 The graph shows a comparison of the rate performance of the doped and regenerated lithium cobalt manganese oxide ternary material prepared in Example 3 of this invention and the unregenerated lithium cobalt manganese oxide ternary material when used as the positive electrode of a lithium-ion battery.

[0030] Figure 4 Cyclic voltammetry curves of the doped, repaired, and regenerated lithium nickel cobalt manganese oxide ternary material prepared in Example 4 of this invention when used as the positive electrode of a lithium-ion battery.

[0031] Figure 5 The Nyquist impedance spectra of the doped and regenerated lithium nickel cobalt manganese oxide ternary material and the unregenerated lithium nickel cobalt manganese oxide ternary material prepared in Example 5 of this invention when used as the positive electrode of a lithium-ion battery. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. Unless otherwise stated, the raw materials and reagents used in the embodiments are commercially available products; reagents, instruments, or operating procedures not described in this invention are all things that can be conventionally determined by those skilled in the art.

[0033] The electrochemical performance of the materials obtained in each embodiment, comparative example, and experimental example of the present invention was tested using the following methods.

[0034] 1. Preparation of the positive electrode sheet: 70 mg of the doped and regenerated lithium nickel cobalt manganese oxide ternary material to be tested was mixed with 20 mg of conductive carbon and ground under infrared lamp irradiation for 10–15 min. 335 μL of a 30 mg / mL polyvinylidene fluoride-N-methylpyrrolidone solution was added to the ground mixture, and the mixture was magnetically stirred for 12 h to obtain the positive electrode slurry. The positive electrode slurry was coated onto aluminum foil or carbon-coated aluminum foil, dried at 60 °C for 2 h, and then vacuum dried at 120 °C for 12 h. The slurry was then cut into circular electrode sheets with a diameter of 12 mm to serve as the positive electrode sheet. The areal loading of the active material was controlled at 4–6 mg / cm². 2 .

[0035] 2. Button cell assembly: Using the prepared positive electrode as the positive electrode, lithium foil as the negative electrode, and Celgard 2500 as the separator, 70-80 μL of electrolyte (LB-014) was added, and CR2032 button cells were assembled under a pressure of 500 MPa. After the assembled cells were allowed to stand for 1 h, electrochemical performance tests were performed.

[0036] 3. Electrochemical performance testing (1) Cyclic performance test: Cyclic performance test is performed at a current density of 0.5 C within a voltage range of 2.5 to 4.3 V.

[0037] (2) Rate performance test: Within the voltage range of 2.5 to 4.3 V, the rate performance test is carried out with current densities of 0.5 C, 1 C, 2 C to 5 C and then back to 0.5 C.

[0038] (3) Cyclic voltammetry (CV) test: Cyclic voltammetry curves were tested at a scan rate of 0.1 to 0.5 mV / s.

[0039] (4) Electrochemical impedance spectroscopy (EIS) test: Nyquist impedance spectrum was tested in the frequency range of 0.01 Hz to 100 kHz.

[0040] Example 1: Preparation of doped and repaired regenerated lithium nickel cobalt manganese oxide ternary materials This embodiment provides a method for preparing doped and repaired regenerated lithium nickel cobalt manganese oxide ternary materials, the specific steps of which are as follows: S1: Prepare a mixed alkaline solution of 1 mol / L sodium hydroxide and potassium hydroxide. Add 2 g of waste lithium nickel cobalt manganese oxide material to the alkaline solution and stir continuously for 20 min. After stirring, wash the material 6 times with deionized water by centrifugation to remove excess alkaline solution, and then dry it. Spread the alkaline-treated waste lithium nickel cobalt manganese oxide evenly in a crucible, crush any large clumps with a spoon to smooth the surface, and place the crucible open in a muffle furnace. Heat the crucible to 400℃ at a rate of 5℃ / min and hold for 2 h to obtain activated lithium nickel cobalt manganese oxide ternary material.

[0041] S2: Weigh 200 mg of the activated lithium nickel cobalt manganese oxide ternary material and place it in a clean agate mortar. Simultaneously weigh 9.9 mg of lithium hydroxide and 42.46 mg of lithium nitrate and mix them with the activated lithium nickel cobalt manganese oxide ternary material. Grind under infrared lamp irradiation for 10 min, then transfer to a crucible and place it in a muffle furnace. Heat the crucible to 300℃ at a heating rate of 5℃ / min and hold for 4 h. Place the sample in a centrifuge tube, wash it 6 times with deionized water, and then dry it to obtain lithium nickel cobalt manganese oxide ternary material after one lithium replenishment and regeneration.

[0042] S3: Lithium carbonate and lithium benzoate were used as a composite lithium source (the molar ratio of lithium carbonate to lithium benzoate was 1:1), and mixed with the nickel-cobalt-manganese ternary material regenerated from the first lithium replenishment at a molar ratio of 0.3:1. The mixture was then ground for 15 min under infrared irradiation. Subsequently, a dopant, a mixture of cerium nitrate and neodymium oxide (mass ratio of cerium nitrate to neodymium oxide was 1:1), was added to the system. The total mass of the dopant was 1 wt.% of the total mass of the waste nickel-cobalt-manganese ternary material. The resulting mixture was placed in a crucible and heated to 850°C in a muffle furnace at a heating rate of 5°C / min and held for 6 h to obtain the doped and repaired nickel-cobalt-manganese ternary material.

[0043] Example 2: Preparation of doped repair and regenerated lithium nickel cobalt manganese oxide ternary materials This embodiment provides a method for preparing doped and repaired regenerated lithium nickel cobalt manganese oxide ternary materials. The specific implementation steps are as follows: S1: Prepare a mixed alkaline solution of 1 mol / L barium hydroxide and potassium hydroxide; put 2 g of waste lithium nickel cobalt manganese oxide material into the alkaline solution and stir continuously for 20 min. After stirring, wash with deionized water 6 times by centrifugation to remove excess alkaline solution, and then dry; take the alkaline solution treated waste lithium nickel cobalt manganese oxide and spread it evenly in a crucible, crush the large clumps with a spoon to make the surface smooth, place the crucible open in a muffle furnace, heat it to 400℃ at a heating rate of 5℃ / min and hold it for 2 h to obtain activated lithium nickel cobalt manganese oxide ternary material.

[0044] S2: Weigh 200 mg of activated lithium nickel cobalt manganese oxide ternary material and place it in a clean agate mortar. At the same time, weigh 6.07 mg of lithium carbonate and 5.42 mg of lithium acetate and mix them with the activated lithium nickel cobalt manganese oxide ternary material. Grind under infrared lamp irradiation for 10 min and then transfer to a crucible. Place it in a muffle furnace and heat it to 300℃ at a heating rate of 5℃ / min and keep it at that temperature for 4 h. Place the sample in a centrifuge tube, centrifuge and wash it 6 times with deionized water, and then dry it to obtain lithium nickel cobalt manganese oxide ternary material after one lithium replenishment and regeneration.

[0045] S3: Lithium carbonate and lithium oxalate were used as a composite lithium source (the molar ratio of lithium carbonate to lithium oxalate was 1:1), and mixed with the nickel-cobalt-manganese oxide ternary material regenerated from the first lithium replenishment at a molar ratio of 0.5:1. The mixture was then ground for 15 min under infrared irradiation. Subsequently, a dopant was added to the system. The dopant was a mixture of lanthanum nitrate and gadolinium nitrate (the mass ratio of lanthanum nitrate to gadolinium nitrate was 1:1), and the total mass of the dopant was 2 wt.% of the total mass of the waste nickel-cobalt-manganese oxide ternary material. The resulting mixture was placed in a crucible and heated to 850°C in a muffle furnace at a heating rate of 5°C / min and held for 6 h to obtain the doped and repaired nickel-cobalt-manganese oxide ternary material.

[0046] Example 3: Preparation of doped repair and regenerated lithium nickel cobalt manganese oxide ternary materials This embodiment provides a method for preparing doped and repaired regenerated lithium nickel cobalt manganese oxide ternary materials. The specific implementation steps are as follows: S1: Prepare a 1 mol / L calcium hydroxide alkaline solution; add 2 g of waste lithium nickel cobalt manganese oxide material to the alkaline solution and stir continuously for 20 min. After stirring, wash with deionized water 6 times by centrifugation to remove excess alkaline solution, and then dry; take the alkaline-treated waste lithium nickel cobalt manganese oxide and spread it evenly in a crucible, crush the large clumps with a spoon to make the surface smooth, place the crucible open in a muffle furnace, heat it to 400℃ at a heating rate of 5℃ / min and hold it for 2 h to obtain activated lithium nickel cobalt manganese oxide ternary material.

[0047] S2: Weigh 200 mg of activated lithium nickel cobalt manganese oxide ternary material and place it in a clean agate mortar. At the same time, weigh 30.61 mg of lithium nitrate and 45.22 mg of lithium oxalate and mix them with the activated lithium nickel cobalt manganese oxide ternary material. Grind under infrared lamp irradiation for 10 min and then transfer to a crucible. Place it in a muffle furnace and heat it to 300℃ at a heating rate of 5℃ / min and keep it at that temperature for 4 h. Place the sample in a centrifuge tube, centrifuge and wash it 6 times with deionized water, and then dry it to obtain lithium nickel cobalt manganese oxide ternary material after one lithium replenishment and regeneration.

[0048] S3: Lithium carbonate and lithium nickel cobalt manganese oxide ternary material regenerated from a single lithium replenishment process were mixed at a molar ratio of 1.1:1 and ground under infrared lamp irradiation for 15 min. Then, a dopant was added to the system. The dopant was a mixture of samarium oxide, terbium oxide, and praseodymium chloride (mass ratio of samarium oxide, terbium oxide, and praseodymium chloride was 1:1:1), and the total mass of the dopant was 3 wt.% of the total mass of the waste lithium nickel cobalt manganese oxide ternary material. The resulting mixture was placed in a crucible and heated to 850℃ in a muffle furnace at a heating rate of 5℃ / min and held for 6 h to obtain the doped and repaired lithium nickel cobalt manganese oxide ternary material.

[0049] Example 4: Preparation of doped and repaired regenerated lithium nickel cobalt manganese oxide ternary materials This embodiment provides a method for preparing doped and repaired regenerated lithium nickel cobalt manganese oxide ternary materials. The specific implementation steps are as follows: S1: Prepare a mixed alkaline solution of 1 mol / L barium hydroxide and potassium hydroxide; add 2 g of waste lithium nickel cobalt manganese oxide material to the alkaline solution and stir continuously for 20 min. After stirring, wash with deionized water 6 times by centrifugation to remove excess alkaline solution, and then dry; take the alkaline-treated waste lithium nickel cobalt manganese oxide and spread it evenly in a crucible, crush the large clumps with a spoon to make the surface smooth, place the crucible open in a muffle furnace, heat it to 400℃ at a heating rate of 5℃ / min and hold it for 2 h to obtain activated lithium nickel cobalt manganese oxide ternary material.

[0050] S2: Weigh 200 mg of activated lithium nickel cobalt manganese oxide ternary material and place it in a clean agate mortar. At the same time, weigh 9.9 mg of lithium hydroxide and 45.22 mg of lithium oxalate and mix them with the activated lithium nickel cobalt manganese oxide ternary material. Grind under infrared lamp irradiation for 10 min and then transfer to a crucible. Place it in a muffle furnace and heat it to 300℃ at a heating rate of 5℃ / min and keep it at that temperature for 4 h. Place the sample in a centrifuge tube, centrifuge and wash it 6 times with deionized water, and then dry it to obtain lithium nickel cobalt manganese oxide ternary material after one lithium replenishment and regeneration.

[0051] S3: Lithium nitrate and lithium benzoate were used as a composite lithium source (the molar ratio of lithium nitrate to lithium benzoate was 1:1), and mixed with the nickel-cobalt-manganese ternary material regenerated from the first lithium replenishment at a molar ratio of 0.6:1. The mixture was then ground for 15 min under infrared irradiation. Subsequently, a dopant, a mixture of erbium nitrate and thulium nitrate (the mass ratio of erbium nitrate to thulium nitrate was 1:1), was added to the system. The total mass of the dopant was 4 wt.% of the total mass of the waste nickel-cobalt-manganese ternary material. The resulting mixture was placed in a crucible and heated to 850°C in a muffle furnace at a heating rate of 5°C / min and held for 6 h to obtain the doped and repaired nickel-cobalt-manganese ternary material.

[0052] Example 5: Preparation of doped and repaired regenerated lithium nickel cobalt manganese oxide ternary materials This embodiment provides a method for preparing doped and repaired regenerated lithium nickel cobalt manganese oxide ternary materials. The specific implementation steps are as follows: S1: Prepare a mixed alkaline solution of 1 mol / L sodium hydroxide and calcium hydroxide; add 2 g of waste lithium nickel cobalt manganese oxide material to the alkaline solution and stir continuously for 20 min. After stirring, wash with deionized water 6 times by centrifugation to remove excess alkaline solution, and then dry; take the alkaline-treated waste lithium nickel cobalt manganese oxide and spread it evenly in a crucible, crush the large clumps with a spoon to make the surface smooth, place the crucible open in a muffle furnace, heat it to 400℃ at a heating rate of 5℃ / min and hold it for 2 h to obtain activated lithium nickel cobalt manganese oxide ternary material.

[0053] S2: Weigh 200 mg of activated lithium nickel cobalt manganese oxide ternary material and place it in a clean agate mortar. At the same time, weigh 13.05 mg of lithium hydroxide, 22.98 mg of lithium carbonate and 21.4 mg of lithium nitrate and mix them with the activated lithium nickel cobalt manganese oxide ternary material. Grind under infrared lamp irradiation for 10 min and then transfer it to a crucible. Place it in a muffle furnace and heat it to 300℃ at a heating rate of 5℃ / min and keep it at that temperature for 4 h. Place the sample in a centrifuge tube, centrifuge and wash it 6 times with deionized water and then dry it to obtain lithium nickel cobalt manganese oxide ternary material after one lithium replenishment and regeneration.

[0054] S3: Lithium oxalate and lithium nickel cobalt manganese oxide ternary material regenerated from a single lithium replenishment process are mixed at a molar ratio of 1:1 and ground under infrared lamp irradiation for 15 min. Then, a dopant, a mixture of ytterbium chloride and lutetium nitrate (mass ratio of ytterbium chloride to lutetium nitrate 1:1), is added to the system. The total mass of the dopant is 5 wt.% of the total mass of the waste lithium nickel cobalt manganese oxide ternary material. The resulting mixture is placed in a crucible and heated to 850℃ in a muffle furnace at a heating rate of 5℃ / min and held for 6 h to obtain the doped and regenerated lithium nickel cobalt manganese oxide ternary material.

[0055] Example 6: Preparation of doped and repaired regenerated lithium nickel cobalt manganese oxide ternary materials This embodiment provides a method for preparing doped and repaired regenerated lithium nickel cobalt manganese oxide ternary materials. The specific implementation steps are as follows: S1: Prepare a 1 mol / L mixed alkaline solution of potassium hydroxide, calcium hydroxide, and sodium hydroxide; add 2 g of waste lithium nickel cobalt manganese oxide material to the alkaline solution and stir continuously for 20 min. After stirring, wash with deionized water 6 times by centrifugation to remove excess alkaline solution, and then dry; take the alkaline-treated waste lithium nickel cobalt manganese oxide and spread it evenly in a crucible, crush the large clumps with a spoon to make the surface smooth, place the crucible open in a muffle furnace, heat it to 400℃ at a heating rate of 5℃ / min and hold it for 2 h to obtain activated lithium nickel cobalt manganese oxide ternary material.

[0056] S2: Weigh 200 mg of activated lithium nickel cobalt manganese oxide ternary material and place it in a clean agate mortar. At the same time, weigh 91.63 mg of lithium acetate and 61.09 mg of lithium benzoate and mix them with the activated lithium nickel cobalt manganese oxide ternary material. Grind under infrared lamp irradiation for 10 min and then transfer to a crucible. Place it in a muffle furnace and heat it to 300℃ at a heating rate of 5℃ / min and keep it at that temperature for 4 h. Place the sample in a centrifuge tube, centrifuge and wash it 6 times with deionized water, and then dry it to obtain lithium nickel cobalt manganese oxide ternary material after one lithium replenishment and regeneration.

[0057] S3: Lithium oxalate and lithium benzoate were used as a composite lithium source (the molar ratio of lithium oxalate to lithium benzoate was 1:1), and mixed with the nickel-cobalt-manganese oxide ternary material regenerated from the first lithium replenishment at a molar ratio of 0.4:1. The mixture was then ground for 15 min under infrared irradiation. Subsequently, a dopant, a mixture of europium chloride and thulium chloride (mass ratio of europium chloride to thulium chloride was 1:1), was added to the system. The total mass of the dopant was 6 wt.% of the total mass of the waste nickel-cobalt-manganese oxide ternary material. The resulting mixture was placed in a crucible and heated to 850°C in a muffle furnace at a heating rate of 5°C / min and held for 6 h to obtain the doped and repaired nickel-cobalt-manganese oxide ternary material.

[0058] The following is a comparative example.

[0059] Comparative Example 1: Preparation of doped and repaired regenerated lithium nickel cobalt manganese oxide ternary materials (without a primary lithium replenishment step) The difference between this comparative example and Example 2 is that step S2 is omitted (i.e., there is no lithium replenishment step). The activated material obtained in step S1 is directly subjected to lanthanide doping repair and regeneration in step S3. The total amount of dopant is still 2 wt.%, and other conditions remain unchanged.

[0060] The obtained material was tested using the aforementioned electrochemical performance testing method. Its initial discharge specific capacity at 0.5 C was only 98.31 mAh / g, and its capacity retention after 200 cycles was 61.2%, far lower than the 153.75 mAh / g of Example 2. This indicates that without a lithium replenishment step, the lithium vacancies were not pre-filled, and the lanthanide dopant could not be effectively embedded in the lattice, leading to repair failure.

[0061] Comparative Example 2: Preparation of doped and repaired regenerated lithium nickel cobalt manganese oxide ternary materials (alkali-free washing and pre-calcination steps) The difference between this comparative example and Example 3 is that step S1 is omitted, and the waste material is directly mixed with the lithium source for steps S2 and S3.

[0062] The obtained material was tested using the aforementioned electrochemical performance testing method. The surface of the recycled material showed obvious impurities, with an initial capacity of 115.64 mAh / g at 0.5 C, which plummeted to 82.32 mAh / g after 50 cycles. Scanning electron microscopy revealed residual binder and electrolyte decomposition products on the particle surface. This indicates that alkaline washing and pre-calcination are prerequisites for ensuring effective doping repair; the absence of this step leads to persistent interfacial side reactions.

[0063] Comparative Example 3: Preparation of doped and regenerated lithium nickel cobalt manganese oxide ternary materials (lanthanide doping repair and regeneration steps omitted). The difference between this comparative example and Example 5 is that the lanthanide compound doping in step S3 is omitted. That is, the material after the first lithium replenishment and regeneration is only subjected to a second lithium replenishment (adding a lithium source) and sintered under the same conditions, without adding any lanthanide elements. Other conditions are the same as in Example 5.

[0064] The obtained material was tested using the aforementioned electrochemical performance testing method. Its initial discharge specific capacity at 0.5 C was 130.21 mAh / g, and the capacity retention after 200 cycles was only 71.54%. Scanning electron microscopy revealed that a dense doped modification layer was not formed on the particle surface, and obvious microcracks and interface impurities were present. Electrochemical impedance spectroscopy showed that its charge transfer impedance was 165.85 Ω, significantly higher than the 107.43 Ω in Example 5. These results indicate that omitting the lanthanide doping step, although stepwise lithium supplementation can partially restore the layered structure and capacity of the material, it cannot effectively expand the interplanar spacing, suppress cation mixing, or construct a surface protective layer, leading to a significant decrease in the material's cycle stability and rate performance. Therefore, lanthanide doping is an essential technical feature of this invention, and its synergistic effect with stepwise lithium supplementation is necessary to achieve significant technical effects.

[0065] The following experimental examples demonstrate the beneficial effects of the present invention.

[0066] Example 1: Optimization of Alkali Washing Concentration in the Preparation Process Referring to Example 2, only the concentration of the alkali solution in step S1 was changed, and the treatment effects of 0.5 mol / L, 1.0 mol / L, and 2.0 mol / L alkali solutions were investigated. The obtained materials were tested using the aforementioned electrochemical performance testing method.

[0067] When the alkali concentration is 0.5 mol / L, residual binder remains on the material surface, with an initial capacity of 138.38 mAh / g at 0.5 C and a retention rate of 71.26% after 200 cycles. At a concentration of 1.0 mol / L, the surface is clean with no residual lithium or byproducts, and the initial capacity is 155.8 mAh / g with a retention rate of 83.5%. At a concentration of 2.0 mol / L, slight corrosion pits appear on the surface, with an initial capacity of 136.22 mAh / g and a retention rate of 76.41%. Therefore, 1.0 mol / L is the optimal alkali washing concentration; concentrations that are too low result in poor impurity removal, while concentrations that are too high damage the material surface.

[0068] Example 2: Optimization of the stepwise lithium replenishment ratio in the preparation process With a fixed total lithium replenishment amount to maintain a lithium to transition metal molar ratio of 1:1, the lithium source molar ratio in the primary lithium replenishment (step S2) and secondary lithium replenishment (step S3) was adjusted. Following the preparation method of Example 2, only the lithium source ratio in S2 and S3 was changed. The obtained material was tested using the aforementioned electrochemical performance testing method.

[0069] When the ratio of primary to secondary lithium sources is 0:1 (i.e., one-step lithium replenishment), the final lithium-nickel mixing degree is 3.8%, and the retention rate after 200 cycles at 0.5 C is 72.51%. When the ratio is 0.3:0.7, the mixing degree is 2.7%, and the retention rate is 77.9%. When the ratio is 0.5:0.5, the molar ratio after one lithium replenishment is 0.91, the mixing degree is 1.9%, and the retention rate is 83.2%. When the ratio is 0.7:0.3, the molar ratio after one lithium replenishment is 0.98, the mixing degree is 2.3%, and the retention rate is 79.61%. When the ratio is 1:0 (i.e., only one lithium replenishment), the mixing degree is 3.1%, and the retention rate is 74.31%. It can be seen that the optimal lithium source molar ratio for primary and secondary lithium replenishment is around 1:1. Too high a primary lithium replenishment ratio can easily lead to residual lithium on the surface, while too low a ratio will not be able to fully repair the crystal lattice.

[0070] Example 3: Optimization of Lanthanide Doping in the Preparation Process Referring to Example 2, lanthanum nitrate was used as a dopant, and the doping amounts were set to 0.5 wt.%, 1 wt.%, 2 wt.%, 3 wt.%, 4 wt.%, 5 wt.%, 6 wt.%, and 7 wt.%. The obtained materials were tested using the aforementioned electrochemical performance testing method.

[0071] With a doping concentration of 0.5 wt.%, the cell volume expansion rate is +0.3%, the retention rate after 200 cycles at 0.5 C is 73.23%, and the 5C rate capacity is 91.32 mAh / g; with a doping concentration of 1 wt.%, the expansion rate is +0.6%, the retention rate is 80.58%, and the 5C capacity is 105.77 mAh / g; with a doping concentration of 2 wt.%, the expansion rate is +0.9%, the retention rate is 83.52%, and the 5C capacity is 106.43 mAh / g; with a doping concentration of 3 wt.%, the expansion rate is +1.1%, the retention rate is 81.27%, and the 5C capacity is 109.82 mAh / g; with a doping concentration of 4 wt.%, the expansion rate is +1.2%, the retention rate is 81.66%, and the 5C capacity is 103.52 mAh / g; with a doping concentration of 5 wt.%, the expansion rate is +1.3%, the retention rate is 82.43%, and the 5C capacity is 105.56 mAh / g. The 5C capacity is 102.29 mAh / g; with a doping amount of 6 wt.%, the expansion rate is +1.3%, the retention rate is 81.33%, and the capacity is 102.29 mAh / g. Therefore, the preferred doping amount is 1 wt.% to 6 wt.%. Too low a doping amount cannot effectively repair the layered structure of waste nickel-cobalt-manganese lithium oxide materials, while too high a doping amount can easily lead to disordered arrangement of lanthanide ions, hindering lithium-ion transport.

[0072] Experiment Example 4: Performance Testing of Doped Regenerated Lithium Nickel Cobalt Manganese Oxide Ternary Materials The performance of the doped, repaired, and regenerated lithium nickel cobalt manganese oxide ternary materials prepared in the various embodiments of the present invention was tested using the aforementioned electrochemical performance testing methods, and the results are as follows.

[0073] Figure 1 The image shows the microstructure of the doped, repaired, and regenerated lithium nickel cobalt manganese oxide ternary material prepared in Example 1. Figure 1 It can be seen that the obtained material exhibits micron-sized, polygonal, and near-spherical polyhedral particles, with no particle agglomeration, regular morphology, and uniform particle size distribution.

[0074] Figure 2 This is a long-cycle performance diagram of the doped, repaired, and regenerated lithium nickel cobalt manganese oxide ternary material prepared in Example 2. Figure 2 It can be seen that, compared with the unrepaired and regenerated lithium nickel cobalt manganese oxide ternary material, the doped and regenerated lithium nickel cobalt manganese oxide ternary material, when used as the positive electrode of lithium-ion battery, has a significantly better first discharge specific capacity (153.75 mAh / g) and cycle stability than the unrepaired and regenerated lithium nickel cobalt manganese oxide ternary material (86.6 mAh / g), indicating that the doping and regeneration treatment significantly improves the electrochemical performance of the material.

[0075] Figure 3 This is a rate performance diagram of the doped, repaired, and regenerated lithium nickel cobalt manganese oxide ternary material prepared in Example 3. Figure 3It can be seen that the specific capacity of the doped and regenerated lithium nickel cobalt manganese oxide ternary material is higher than that of the unregenerated comparative material at 0.5 C, 1 C, 2 C and 5 C rates, and the advantage is more obvious at high rate (5 C); when the rate is restored to 0.5 C, the capacity reversibility is good.

[0076] Figure 4 Cyclic voltammetry curves of the doped, repaired, and regenerated lithium nickel cobalt manganese oxide ternary material prepared in Example 4 at different scan rates (0.1-0.5 mV / s). Figure 4 It can be seen that the redox peak current increases with the increase of the scan rate, and the potential difference remains basically stable, indicating that the electrode reaction has good reversibility and diffusion control characteristics.

[0077] Figure 5 The Nyquist impedance spectrum is shown for the doped, repaired, and regenerated lithium nickel cobalt manganese oxide ternary material prepared in Example 5. Figure 5 It can be seen that the nickel-cobalt-manganese ternary material that has been doped and repaired has a smaller charge transfer impedance and better lithium-ion diffusion kinetics than the unrepaired and regenerated comparative material.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a doped, repaired, and regenerated lithium nickel cobalt manganese oxide ternary material, characterized in that: The preparation method includes the following steps: S1. Alkali washing and pre-sintering step: Place the lithium nickel cobalt manganese oxide material in an alkaline solution and stir, wash and dry, and pre-sinter to obtain activated lithium nickel cobalt manganese oxide ternary material. S2, First lithium replenishment step: The activated lithium nickel cobalt manganese oxide ternary material is mixed with the first lithium source, ground under infrared lamp irradiation, sintered for the first time, washed and dried to obtain lithium nickel cobalt manganese oxide ternary material regenerated by first lithium replenishment. S3. Lanthanide doping repair and regeneration step: The nickel cobalt manganese oxide ternary material regenerated by the first lithium replenishment is mixed with a second lithium source and lanthanide compounds, ground under infrared lamp irradiation, and sintered for the second time to obtain the doped repair and regenerated nickel cobalt manganese oxide ternary material.

2. The preparation method according to claim 1, characterized in that: The alkaline solution is selected from at least one of sodium hydroxide solution, potassium hydroxide solution, barium hydroxide solution or calcium hydroxide solution, and the concentration of the alkaline solution is 0.5 mol / L to 2.0 mol / L; preferably, the concentration of the alkaline solution is 1.0 mol / L.

3. The preparation method according to claim 1, characterized in that: The pre-sintering conditions are as follows: heating to 350℃~450℃ at a heating rate of 2℃ / min~10℃ / min and holding at that temperature for 1 h~3 h.

4. The preparation method according to claim 1, characterized in that: The first lithium source and the second lithium source are each independently selected from at least one of lithium hydroxide, lithium carbonate, lithium nitrate, lithium acetate, lithium benzoate, and lithium oxalate.

5. The preparation method according to claim 1, characterized in that: In step S2, the molar ratio of the activated lithium nickel cobalt manganese oxide ternary material to the first lithium source is 1:(0.3~1.1); preferably, the molar ratio of the activated lithium nickel cobalt manganese oxide ternary material to the first lithium source is 1:

1. In step S3, the molar ratio of the lithium nickel cobalt manganese oxide ternary material regenerated by the first lithium replenishment to the second lithium source is 1:(0.3~1.1); preferably, the molar ratio of the lithium nickel cobalt manganese oxide ternary material regenerated by the first lithium replenishment to the second lithium source is 1:

1.

6. The preparation method according to claim 1, characterized in that: The lanthanide compound is selected from at least one oxide, nitrate, or chloride of lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, erbium, thulium, ytterbium, and lutetium; the doping amount of the lanthanide compound is 1 wt.% to 6 wt.% of the total mass of the lithium nickel cobalt manganese oxide ternary material; preferably, the doping amount is 2 wt.% to 3 wt.%.

7. The preparation method according to claim 1, characterized in that: The temperature of the first sintering is 250℃~350℃, and the temperature of the second sintering is 750℃~950℃.

8. A doped, repairable, and regenerated ternary lithium nickel cobalt manganese oxide material, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 7.

9. The doped, repaired, and regenerated lithium nickel cobalt manganese oxide ternary material according to claim 8, characterized in that: In the material, lanthanide elements replace some Ni, Co, and Mn lattice sites in the form of doped atoms, or occupy lithium vacancies, or form lanthanide oxide dispersed phases distributed on the particle surface; the microscopic particle cracks of the material are filled, and a dense doped modified layer is formed on the particle surface.

10. The use of the doped, repaired, and regenerated lithium nickel cobalt manganese oxide ternary material as described in claim 8 or 9 in the preparation of lithium-ion battery cathode materials.

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