A regenerated cathode material with orientation site-induced antiferromagnetic coupling, its preparation method and application

Abstract

This invention discloses a regenerated cathode material with orientation site-induced antiferromagnetic coupling, its preparation method, and its application. The regenerated cathode material with orientation site-induced antiferromagnetic coupling is a regenerated lithium nickel cobalt manganese oxide cathode material. The crystal structure of the regenerated lithium nickel cobalt manganese oxide cathode material contains niobium atoms, which occupy lithium sites in the crystal lattice and locally form Nb-O-Ni coordination structures. The preparation method is as follows: pre-treating waste lithium nickel cobalt manganese oxide cathode material to obtain a cathode material intermediate; mixing the cathode material intermediate, a lithium source, and a niobium source to obtain a powder to be sintered; subjecting the powder to be sintered to high-temperature calcination, and cooling to obtain the regenerated cathode material with orientation site-induced antiferromagnetic coupling. When applied to lithium-ion batteries, it exhibits long-term cycle stability.

Description

Technical Field

[0001] This invention belongs to the field of waste battery recycling and reuse technology, specifically relating to a regenerated positive electrode material with orientation site-induced antiferromagnetic coupling, its preparation method and application. Background Technology

[0002] With the rapid development of electric vehicles and energy storage systems, the demand for lithium-ion batteries has surged, leading to a dramatic increase in the number of waste batteries. Waste ternary layered oxide cathode materials (such as lithium nickel cobalt manganese oxide) contain a large amount of valuable metals (nickel, cobalt, manganese, lithium, etc.), making their recycling significant in terms of both economic and environmental value. Current recycling technologies mainly include pyrometallurgy, hydrometallurgy, and direct regeneration. Compared to the energy-intensive and time-consuming pyrometallurgical and hydrometallurgical technologies, direct regeneration technology can directly repair the composition and crystal structure of waste materials, and is considered a more sustainable strategy. However, existing directly regenerated cathode materials generally suffer from poor cycle stability.

[0003] The commonality of the failure mechanisms lies in the fact that, during long-term cycling, nickel (Ni) ions in the transition metal (TM) layer readily migrate to the lithium (Li) layer, inducing an irreversible phase transition from the layered structure to the spinel / rock salt phase, leading to blockage of lithium-ion transport channels and rapid capacity decay. Researchers widely employ heteroatom doping strategies, but existing doping modification studies largely focus on utilizing the "pillar effect" generated by heteroatoms to physically support the interlayer spacing, or passively suppressing lattice oxygen evolution by introducing high bond energy elements, aiming to delay structural degradation from the perspective of macroscopic lattice parameters or interfacial chemical stability. These conventional strategies often lack in-depth analysis and active control of the microscopic electronic structure between TM and O (especially electron spin configuration and orbital hybridization modes). Because they fail to fundamentally change the binding properties of the Ni–O bond at the quantum mechanical level (usually dominated by unstable π bonds), existing modification methods still have limitations in suppressing the thermodynamic trend of Ni migration and improving long-term cycle life. Therefore, there is an urgent need to develop a high-performance regenerated cathode material and its preparation method that can penetrate into the micro-electronic level and fundamentally stabilize the lattice structure by controlling the bonding orbital characteristics. Summary of the Invention

[0004] In order to solve the problems of poor cycle stability, severe Ni migration and phase transition in existing regenerated cathode materials mentioned in the background art, the purpose of this invention is to provide a regenerated cathode material with orientation site-induced antiferromagnetic coupling, its preparation method and application.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: On the one hand, the present invention provides a regenerated cathode material with orientation site-induced antiferromagnetic coupling, wherein the regenerated cathode material with orientation site-induced antiferromagnetic coupling is a regenerated lithium nickel cobalt manganese oxide (NCM) cathode material, wherein the crystal structure of the regenerated lithium nickel cobalt manganese oxide cathode material contains niobium (Nb) atoms, wherein the niobium atoms occupy lithium sites in the crystal lattice and form a local Nb-O-Ni coordination structure.

[0006] The Nb-O-Ni coordination structure induces strong antiferromagnetic coupling between nickel cations and oxygen anions by adjusting the spin direction and orbital distribution of adjacent oxygen anions through Nb atoms, resulting in Ni–O chemical bonds exhibiting σ-bond-dominated bonding characteristics.

[0007] Furthermore, in the regenerated cathode material with orientation site-induced antiferromagnetic coupling, the molar ratio of niobium to transition metal elements is (0.005-0.02):1. If the niobium doping level is too low, it is insufficient to form effective antiferromagnetic coupling; if the doping level is too high, excessive niobium may form impurity phases (such as LiNbO3) at the grain boundaries, hindering lithium-ion transport.

[0008] Furthermore, the recycled lithium nickel cobalt manganese oxide cathode material includes recycled LiNi 0.5 Co 0.2 Mn 0.3 O2 (NCM523) cathode material, recycled LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811) cathode material, recycled LiNi 0.6 Co 0.2 Mn 0.2 O2 (NCM622) cathode material, etc.

[0009] On the other hand, the present invention provides a method for preparing a regenerated positive electrode material with orientation site-induced antiferromagnetic coupling as described above, comprising the following steps:

[0010] (1) Pretreatment of waste lithium nickel cobalt manganese oxide cathode material to obtain cathode material intermediate;

[0011] (2) The cathode material intermediate, lithium source and niobium source are mixed to obtain the powder to be sintered;

[0012] (3) The powder to be sintered is subjected to high-temperature calcination to achieve lithium replenishment and niobium atom directional doping at lithium vacancies. After cooling, the regenerated cathode material with orientation site-induced antiferromagnetic coupling is obtained.

[0013] This invention utilizes the abundant lithium vacancies pre-existing in waste cathode materials as orientation sites; while replenishing lithium ions, niobium atoms are selectively introduced into the lithium vacancies.

[0014] Further, the waste lithium nickel cobalt manganese oxide cathode material mentioned in step (1) is obtained by the following method: the failed lithium nickel cobalt manganese oxide cathode material is dispersed in sodium hydroxide solution and stirred vigorously to dissolve organic residues; then centrifuged and washed with water until a neutral pH value (7.0±0.2) is reached; the purified precipitate is dried and heat-treated to obtain the waste lithium nickel cobalt manganese oxide cathode material.

[0015] Furthermore, the concentration of the sodium hydroxide solution is 1 mol / L;

[0016] And / or, the drying temperature is 60°C, and the drying time is 12-24 hours;

[0017] And / or, the heat treatment temperature is 400°C and the heat treatment time is 2 hours.

[0018] Furthermore, the pretreatment in step (1) includes partial lithium element replenishment and impurity removal.

[0019] Furthermore, the cathode material intermediate described in step (1) is obtained through a low-temperature molten salt pre-lithiation and cleaning / drying process. The core of this step is to obtain a clean and pre-lithiated intermediate, and the specific lithium replenishment method is not limited to a specific molten salt formulation.

[0020] Furthermore, step (1) specifically involves:

[0021] Waste lithium nickel cobalt manganese oxide cathode material and low-temperature molten salt system were ground in an infrared lamp-assisted drying environment until they reached a homogeneous state, thus obtaining a mixture.

[0022] The mixture was subjected to low-temperature calcination, cooled, washed and dried with water to obtain the cathode material intermediate.

[0023] Furthermore, the low-temperature molten salt system includes lithium hydroxide, lithium nitrate, and an organic lithium salt additive; the organic lithium salt additive is lithium benzoate; the mass ratio of lithium hydroxide, lithium nitrate, and lithium benzoate is 9.9:42.46:133.49.

[0024] And / or, the mass ratio of the waste nickel-cobalt-manganese lithium cathode material to the low-temperature molten salt system is 200:185.85;

[0025] And / or, the low-temperature calcination temperature is 300°C, and the low-temperature calcination time is 4 hours.

[0026] Furthermore, the lithium source mentioned in step (2) is lithium carbonate;

[0027] And / or, the niobium source is at least one of niobium pentoxide and ammonium oxalate hydrate;

[0028] And / or, the mass ratio of the lithium source to the cathode material intermediate is (27.75-55.5):150, and the amount of lithium source added is usually slightly excessive to compensate for possible lithium volatilization during subsequent high-temperature processes and to ensure that Nb atoms can successfully occupy Li sites rather than TM sites.

[0029] And / or, the mass ratio of the niobium source to the cathode material intermediate is (1-4):150.

[0030] Furthermore, the high-temperature calcination temperature in step (3) is 800-900℃, and the high-temperature calcination time is 2-10h. Under this specific high-temperature window, since the waste cathode material still retains certain intrinsic lithium vacancy characteristics after pretreatment, it drives the high-valence Nb atoms to migrate directionally to the Li layer sites. When the Nb atoms occupy the Li sites, they not only play a physical "pillar" role, but more importantly, they can adjust the spin direction and orbital distribution of adjacent oxygen anions, inducing strong antiferromagnetic coupling between Ni ions and O ions, causing a fundamental change in the properties of the Ni–O chemical bond - from the easily broken π bond to the highly stable σ bond.

[0031] On the other hand, the present invention provides an application of the regenerated cathode material with orientation site-induced antiferromagnetic coupling as described above or the regenerated cathode material with orientation site-induced antiferromagnetic coupling prepared by any of the preparation methods described above in lithium-ion batteries.

[0032] Lithium-ion batteries containing the regenerated cathode material with orientation site-induced antiferromagnetic coupling of the present invention exhibit long cycle stability.

[0033] Compared with the prior art, the present invention has at least the following beneficial effects:

[0034] This invention utilizes the abundant intrinsic lithium vacancies in waste cathode materials to introduce Nb atoms, enhancing the hybridization of Ni 3d and O 2p orbitals through induced antiferromagnetic coupling. This promotes the transformation of the Ni–O bond from unstable π-bond dominance to stable σ-bond dominance. This robust bonding network effectively suppresses Ni migration during cycling and inhibits the transformation of the layered structure to the spinel / rock salt phase. Thanks to the stable crystal structure and improved lithium-ion transport kinetics, the resulting regenerated cathode material exhibits excellent long-cycle performance, demonstrating superior structural stability and capacity retention during long-cycle operation. Experiments show that after 750 cycles at 0.5C, its capacity retention can reach approximately 60%, significantly better than unrepaired failed cathode materials, undoped regenerated cathode materials, and cathode materials doped with Nb at TM sites. Furthermore, the direct regeneration process employed in this invention is simple, low-cost, and environmentally friendly, avoiding strong acid leaching and complex separation and purification steps. Compared to traditional pyrometallurgical and wet recycling methods, it has lower energy consumption, lower carbon emissions, and higher economic benefits. Attached Figure Description

[0035] The accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0036] Figure 1 The X-ray diffraction patterns of AF-RSNCM prepared in Example 1 and SNCM prepared in Comparative Example 1 are shown below.

[0037] Figure 2 Scanning electron microscope images of AF-RSNCM prepared in Example 1 of the present invention and SNCM prepared in Comparative Example 1;

[0038] Figure 3 The charge-discharge curves of AF-RSNCM prepared in Example 1, SNCM prepared in Comparative Example 1, and RSNCM prepared in Comparative Example 2 after activation at a rate of 0.5C are shown.

[0039] Figure 4 The images show the long-cycle curves of AF-RSNCM prepared in Example 1, SNCM prepared in Comparative Example 1, RSNCM prepared in Comparative Example 2, and Nb-NCM prepared in Comparative Example 3 at a 0.5C rate.

[0040] Figure 5This is a schematic diagram illustrating the principle of preparing regenerated cathode material with orientation site-induced antiferromagnetic coupling in an embodiment of the present invention, and a schematic diagram illustrating the cycling process of regenerated cathode material with orientation site-induced antiferromagnetic coupling. Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0042] Example 1

[0043] Preparation of regenerated cathode materials with orientation site-induced antiferromagnetic coupling:

[0044] (1) 200mg of waste lithium nickel cobalt manganese oxide (LiNi) 0.5 Co 0.2 Mn 0.3 The O2 cathode material (i.e., the SNCM prepared in Comparative Example 1) was placed in an agate mortar, and 9.9 mg of lithium hydroxide, 42.46 mg of lithium nitrate, and 133.49 mg of lithium benzoate were added to the mortar. The mixture was manually ground for 10 min under infrared lamp-assisted drying until the powder was homogeneous, yielding a mixture. The mixture was then evenly spread in an alumina ceramic boat, placed in a muffle furnace, heated to 300 °C at a heating rate of 5 °C / min, and calcined at this temperature for 4 h. After naturally cooling to room temperature in the furnace, the sample was removed. The sample was repeatedly washed with deionized water and centrifuged at high speed (10,000 rpm, 5 min each time). The precipitate was collected and placed in a vacuum drying oven at 120 °C for 12 h to obtain the cathode material intermediate.

[0045] (2) Place 150mg of the cathode material intermediate obtained in step (1) in a mortar, add 27.75mg of lithium carbonate as a supplementary lithium source for high-temperature sintering, and add 2mg of niobium pentoxide as a doping niobium source. Under the environment of infrared lamp-assisted drying, grind manually for 10min until the mixed powder is uniform and obtain the powder to be sintered.

[0046] (3) The powder to be sintered obtained in step (2) is evenly spread in an alumina ceramic boat, placed in a muffle furnace, heated to 850°C at a heating rate of 5°C / min, and calcined at a constant temperature for 6 hours. After the high temperature is completed, it is naturally cooled with the furnace, ground and sieved to obtain the regenerated cathode material with orientation site induced antiferromagnetic coupling, denoted as AF-RSNCM. The molar ratio of niobium and transition metal elements in the regenerated cathode material with orientation site induced antiferromagnetic coupling is 0.01:1.

[0047] Example 2

[0048] Preparation of regenerated cathode materials with orientation site-induced antiferromagnetic coupling:

[0049] (1) 200mg of waste lithium nickel cobalt manganese oxide (LiNi) 0.5 Co 0.2 Mn 0.3 The O2 cathode material (i.e., the SNCM prepared in Comparative Example 1) was placed in an agate mortar, and 9.9 mg of lithium hydroxide, 42.46 mg of lithium nitrate, and 133.49 mg of lithium benzoate were added to the mortar. The mixture was manually ground for 10 min under infrared lamp-assisted drying until the powder was homogeneous, yielding a mixture. The mixture was then evenly spread in an alumina ceramic boat, placed in a muffle furnace, heated to 300 °C at a heating rate of 5 °C / min, and calcined at this temperature for 4 h. After naturally cooling to room temperature in the furnace, the sample was removed. The sample was repeatedly washed with deionized water and centrifuged at high speed (10,000 rpm, 5 min each time). The precipitate was collected and placed in a vacuum drying oven at 120 °C for 12 h to obtain the cathode material intermediate.

[0050] (2) Place 150mg of the cathode material intermediate obtained in step (1) in a mortar, add 27.75mg of lithium carbonate as a supplementary lithium source for high-temperature sintering, and add 1mg of niobium pentoxide as a doping niobium source. Under the environment of infrared lamp-assisted drying, grind manually for 10min until the mixed powder is uniform and obtain the powder to be sintered.

[0051] (3) The powder to be sintered obtained in step (2) is evenly spread in an alumina ceramic boat, placed in a muffle furnace, heated to 850°C at a heating rate of 5°C / min, and calcined at a constant temperature for 6 hours. After the high temperature is completed, it is naturally cooled with the furnace, ground and sieved to obtain the regenerated cathode material with orientation site induced antiferromagnetic coupling, denoted as AF-RSNCM. The molar ratio of niobium and transition metal elements in the regenerated cathode material with orientation site induced antiferromagnetic coupling is 0.005:1.

[0052] Example 3

[0053] Preparation of regenerated cathode materials with orientation site-induced antiferromagnetic coupling:

[0054] (1) 200mg of waste lithium nickel cobalt manganese oxide (LiNi) 0.5 Co 0.2 Mn 0.3The O2 cathode material (i.e., the SNCM prepared in Comparative Example 1) was placed in an agate mortar, and 9.9 mg of lithium hydroxide, 42.46 mg of lithium nitrate, and 133.49 mg of lithium benzoate were added to the mortar. The mixture was manually ground for 10 min under infrared lamp-assisted drying until the powder was homogeneous, yielding a mixture. The mixture was then evenly spread in an alumina ceramic boat, placed in a muffle furnace, heated to 300 °C at a heating rate of 5 °C / min, and calcined at this temperature for 4 h. After naturally cooling to room temperature in the furnace, the sample was removed. The sample was repeatedly washed with deionized water and centrifuged at high speed (10,000 rpm, 5 min each time). The precipitate was collected and placed in a vacuum drying oven at 120 °C for 12 h to obtain the cathode material intermediate.

[0055] (2) Place 150mg of the cathode material intermediate obtained in step (1) in a mortar, add 27.75mg of lithium carbonate as a supplementary lithium source for high-temperature sintering, and add 4mg of niobium pentoxide as a doping niobium source. Under the environment of infrared lamp-assisted drying, grind manually for 10min until the mixed powder is uniform and obtain the powder to be sintered.

[0056] (3) The powder to be sintered obtained in step (2) is evenly spread in an alumina ceramic boat, placed in a muffle furnace, heated to 850°C at a heating rate of 5°C / min, and calcined at a constant temperature for 6 hours. After the high temperature is completed, it is naturally cooled with the furnace, ground and sieved to obtain the regenerated cathode material with orientation site-induced antiferromagnetic coupling, denoted as AF-RSNCM. The molar ratio of niobium and transition metal elements in the regenerated cathode material with orientation site-induced antiferromagnetic coupling is 0.02:1.

[0057] Example 4

[0058] Preparation of regenerated cathode materials with orientation site-induced antiferromagnetic coupling:

[0059] (1) 200mg of waste lithium nickel cobalt manganese oxide (LiNi) 0.5 Co 0.2 Mn 0.3The O2 cathode material (i.e., the SNCM prepared in Comparative Example 1) was placed in an agate mortar, and 9.9 mg of lithium hydroxide, 42.46 mg of lithium nitrate, and 133.49 mg of lithium benzoate were added to the mortar. The mixture was manually ground for 10 min under infrared lamp-assisted drying until the powder was homogeneous, yielding a mixture. The mixture was then evenly spread in an alumina ceramic boat, placed in a muffle furnace, heated to 300 °C at a heating rate of 5 °C / min, and calcined at this temperature for 4 h. After naturally cooling to room temperature in the furnace, the sample was removed. The sample was repeatedly washed with deionized water and centrifuged at high speed (10,000 rpm, 5 min each time). The precipitate was collected and placed in a vacuum drying oven at 120 °C for 12 h to obtain the cathode material intermediate.

[0060] (2) Place 150mg of the cathode material intermediate obtained in step (1) in a mortar, add 27.75mg of lithium carbonate as a supplementary lithium source for high-temperature sintering, and add 2mg of niobium pentoxide as a doping niobium source. Under the environment of infrared lamp-assisted drying, grind manually for 10min until the mixed powder is uniform and obtain the powder to be sintered.

[0061] (3) The powder to be sintered obtained in step (2) is evenly spread in an alumina ceramic boat, placed in a muffle furnace, heated to 800°C at a heating rate of 5°C / min, and calcined at a constant temperature for 6 hours. After the high temperature is completed, it is naturally cooled with the furnace, ground and sieved to obtain the regenerated cathode material with orientation site-induced antiferromagnetic coupling, denoted as AF-RSNCM. The molar ratio of niobium and transition metal elements in the regenerated cathode material with orientation site-induced antiferromagnetic coupling is 0.01:1.

[0062] Example 5

[0063] Preparation of regenerated cathode materials with orientation site-induced antiferromagnetic coupling:

[0064] (1) 200mg of waste lithium nickel cobalt manganese oxide (LiNi) 0.5 Co 0.2 Mn 0.3The O2 cathode material (i.e., the SNCM prepared in Comparative Example 1) was placed in an agate mortar, and 9.9 mg of lithium hydroxide, 42.46 mg of lithium nitrate, and 133.49 mg of lithium benzoate were added to the mortar. The mixture was manually ground for 10 min under infrared lamp-assisted drying until the powder was homogeneous, yielding a mixture. The mixture was then evenly spread in an alumina ceramic boat, placed in a muffle furnace, heated to 300 °C at a heating rate of 5 °C / min, and calcined at this temperature for 4 h. After naturally cooling to room temperature in the furnace, the sample was removed. The sample was repeatedly washed with deionized water and centrifuged at high speed (10,000 rpm, 5 min each time). The precipitate was collected and placed in a vacuum drying oven at 120 °C for 12 h to obtain the cathode material intermediate.

[0065] (2) Place 150mg of the cathode material intermediate obtained in step (1) in a mortar, add 27.75mg of lithium carbonate as a supplementary lithium source for high-temperature sintering, and add 2mg of niobium pentoxide as a doping niobium source. Under the environment of infrared lamp-assisted drying, grind manually for 10min until the mixed powder is uniform and obtain the powder to be sintered.

[0066] (3) The powder to be sintered obtained in step (2) is evenly spread in an alumina ceramic boat, placed in a muffle furnace, heated to 900°C at a heating rate of 5°C / min, and calcined at a constant temperature for 6 hours. After the high temperature is completed, it is naturally cooled with the furnace, ground and sieved to obtain the regenerated cathode material with orientation site-induced antiferromagnetic coupling, denoted as AF-RSNCM. The molar ratio of niobium and transition metal elements in the regenerated cathode material with orientation site-induced antiferromagnetic coupling is 0.01:1.

[0067] Comparative Example 1

[0068] This comparative example provides an unrepaired failed cathode material (SNCM) to verify the effect of regeneration and repair. Its preparation method is as follows:

[0069] The failed NCM523 cathode material was pretreated using an alkaline treatment method. 2g of the failed NCM523 cathode material was dispersed in a 1mol / L sodium hydroxide solution and stirred vigorously (600rpm) for 15min to dissolve organic residues. It was then centrifuged and washed with deionized water until a neutral pH (7.0±0.2) was reached. The purified precipitate was dried at 60℃ for 12h and then heat-treated in a muffle furnace at 400℃ for 2h to remove residual binders and restore crystallinity, thus preparing unrepaired failed cathode material, denoted as SNCM.

[0070] Comparative Example 2

[0071] This comparative example provides a regenerated cathode material (RSNCM) without Nb doping to verify the effect of Nb doping. Its preparation method is as follows:

[0072] (1) 200mg of waste lithium nickel cobalt manganese oxide (LiNi) 0.5 Co 0.2 Mn 0.3 The O2 cathode material (i.e., the SNCM prepared in Comparative Example 1) was placed in an agate mortar, and 9.9 mg of lithium hydroxide, 42.46 mg of lithium nitrate, and 133.49 mg of lithium benzoate were added to the mortar. The mixture was manually ground for 10 min under infrared lamp-assisted drying until the powder was homogeneous, yielding a mixture. The mixture was then evenly spread in an alumina ceramic boat, placed in a muffle furnace, heated to 300 °C at a heating rate of 5 °C / min, and calcined at this temperature for 4 h. After naturally cooling to room temperature in the furnace, the sample was removed. The sample was repeatedly washed with deionized water and centrifuged at high speed (10,000 rpm, 5 min each time). The precipitate was collected and placed in a vacuum drying oven at 120 °C for 12 h to obtain the cathode material intermediate.

[0073] (2) Place 150mg of the cathode material intermediate obtained in step (1) in a mortar, add 27.75mg of lithium carbonate as a supplementary lithium source for high-temperature sintering, and grind manually for 10min under the environment of infrared lamp-assisted drying until the mixed powder is uniform, and obtain the powder to be sintered.

[0074] (3) The powder to be sintered obtained in step (2) is evenly spread in an alumina ceramic boat, placed in a muffle furnace, heated to 850°C at a heating rate of 5°C / min, and calcined at a constant temperature for 6 hours. After the high temperature is completed, the powder is naturally cooled in the furnace, ground and sieved to obtain the undoped Nb regenerated cathode material, denoted as RSNCM.

[0075] Comparative Example 3

[0076] This comparative example provides a Nb-doped cathode material (Nb-NCM) synthesized via a conventional solid-state method at TM sites, used to verify the unique advantages of the "regeneration + Li site orientation doping" method of this invention. The preparation method is as follows:

[0077] NiSO4·6H2O, CoSO4·7H2O, MnSO4·H2O, and C4H4NNbO9·nH2O were dissolved in deionized water in a molar ratio of Ni, Co, Mn, and Nb of 0.49:0.2:0.3:0.01 to form a mixed salt solution with a total concentration of 1 mol / L. At 70°C, 20 mL of the mixed salt solution was added dropwise to 50 mL of ammonia solution (pH=11) with continuous stirring at 600 rpm. Simultaneously, 2 mol / L sodium hydroxide solution and 1 mol / L ammonia solution were added to maintain the reaction pH at 11. After the addition of the mixed salt solution was complete, the precipitation reaction was continued at 70°C for 12 h, followed by aging at the same temperature for another 12 h. The precipitate was collected by filtration, washed six times with deionized water, and then dried in a forced-air oven at 80°C for 12 h to obtain the hydroxide precursor powder. 100 mg of hydroxide precursor powder was mixed with 25.2 mg of lithium hydroxide and ground for 10 min. The mixture was calcined in a muffle furnace at a heating rate of 5 °C / min, first at 450 °C for 5 h, and then at 850 °C for 10 h. After natural cooling to room temperature, Nb-doped cathode material at TM sites was obtained, denoted as Nb-NCM.

[0078] To investigate the structural evolution of waste nickel-cobalt-manganese lithium cathode materials during the regeneration process, in-situ X-ray diffraction (XRD) and scanning electron microscopy (SEM) tests were performed on the AF-RSNCM prepared in Example 1 and the SNCM prepared in Comparative Example 1. The results are as follows: Figure 1 and Figure 2 As shown. From Figure 1 As can be seen, the (003) diffraction peak of the SNCM shifts to a lower angle compared to the diffraction peak of the AF-RSNCM. This shift is attributed to the presence of lithium vacancies in the SNCM, which increases the electrostatic repulsion between adjacent oxygen layers and leads to c-axis elongation. With the replenishment of lithium ions in the SNCM, the electrostatic repulsion is eliminated, resulting in c-axis contraction. Figure 2 As can be seen, the surface of SNCM particles is rough with obvious microcracks, which may be related to the in-plane migration of TM atoms during cycling. In contrast, the surface of AF-RSNCM appears smooth, indicating that the introduction of niobium does not affect morphology recovery.

[0079] Preparation of CR2032 coin cell: Active material (AF-RSNCM, SNCM, RSNCM, or Nb-NCM), conductive agent (carbon black Super P), and binder (polyvinylidene fluoride PVDF) are mixed at a mass ratio of 8:1:1. An appropriate amount of N-methylpyrrolidone (NMP) solvent is added, and the mixture is stirred until homogeneous to form a slurry. The slurry is uniformly coated onto a carbon-coated aluminum foil current collector, first dried by forced air at 80℃, and then transferred to a vacuum drying oven at 120℃ for 12 hours. After cooling, it is punched into circular electrode sheets with a diameter of 12mm, controlling the active material loading to be 3-5 mg / cm³. –2 A lithium metal sheet was used as the negative electrode; Celgard 2500 was used as the separator; the electrolyte was LiPF6 dissolved in a mixed solvent of EC / DEC / DMC, with a volume ratio of EC, DEC, and DMC of 1:1:1, and a LiPF6 concentration of 1 mol / L. CR2032 coin cells were assembled in an argon-filled glove box (water and oxygen content both <0.1 ppm).

[0080] The electrochemical performance of CR2032 coin cells assembled using AF-RSNCM prepared in Example 1, SNCM prepared in Comparative Example 1, RSNCM prepared in Comparative Example 2, and Nb-NCM prepared in Comparative Example 3 was tested at a rate of 0.5C, with a test voltage window of 2.5-4.3V. The test results are as follows. Figure 3 and Figure 4 As shown.

[0081] Figure 3 The charge-discharge curves of SNCM, RSNCM, and AF-RSNCM activated at a charge-discharge rate of 0.5C within a voltage window of 2.5–4.3V are shown. Figure 3 As can be seen from the data, the discharge capacity of AF-RSNCM is 142.14 mAh g. –1 It is comparable to RSNCM and significantly higher than SNCM (113.79 mAh g). –1 Due to structural degradation, SNCM exhibits a large polarization voltage. Thanks to the effective direct regeneration of spent cathode materials, the polarization voltages of both RSNCM and AF-RSNCM are significantly reduced.

[0082] Figure 4 The long-term cycling performance of SNCM, RSNCM, AF-RSNCM, and Nb-NCM at a charge / discharge rate of 0.5C is demonstrated. Figure 4As can be seen, AF-RSNCM retains approximately 60% of its initial capacity after 750 cycles, while RSNCM exhibits a lower capacity retention (approximately 50% after 300 cycles). Although Nb-NCM demonstrates good cycle stability after 750 cycles (capacity retention of 42%), its performance is still inferior to AF-RSNCM (capacity retention of approximately 60% after 750 cycles). The superior performance of AF-RSNCM compared to Nb-NCM is attributed to the specific dopant sites. During regeneration, the abundant intrinsic Li vacancies in the spent cathode material facilitate Nb atom doping at Li sites. This specific lithium site doping alters the electronic structure, inducing strong Ni–O antiferromagnetic coupling. In contrast, in conventionally synthesized Nb-NCM, Nb atoms tend to occupy TM sites. While TM site doping provides some structural stability, it cannot induce the observed strong antiferromagnetic coupling as Li site doping; therefore, its ability to improve material performance is limited.

[0083] The schematic diagram of the principle of preparing the orientation site-induced antiferromagnetic coupling regenerated cathode material and the schematic diagram of the cycling process of the orientation site-induced antiferromagnetic coupling regenerated cathode material are shown in the embodiments of the present invention. Figure 5 As shown, Nb is selectively introduced into intrinsic Li vacancies during the high-temperature calcination stage of direct regeneration to modulate the spin direction and orbital distribution of the bridged oxygen anion. Changes in spin direction and orbital distribution enhance the antiferromagnetic coupling between the Ni cation and the bridged O anion, thereby forming a more stable Ni–O structure dominated by σ bonds. This bond reconstruction effectively suppresses nickel migration and stabilizes the layered structure. Therefore, the regenerated cathode material prepared by the method proposed in this invention exhibits excellent electrochemical performance and significantly improved cycle stability. This establishes a mechanistic and industrially feasible pathway for producing high-performance regenerated cathode materials and provides valuable design principles for sustainable and closed-loop battery recycling.

[0084] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present invention.

Claims

1. A regenerated cathode material with orientation site-induced antiferromagnetic coupling, characterized in that, The regenerated cathode material with orientation site-induced antiferromagnetic coupling is a regenerated lithium nickel cobalt manganese oxide cathode material. The crystal structure of the regenerated lithium nickel cobalt manganese oxide cathode material contains niobium atoms, which occupy lithium sites in the crystal lattice and form Nb-O-Ni coordination structures locally.

2. The regenerated positive electrode material with orientation site-induced antiferromagnetic coupling according to claim 1, characterized in that, The molar ratio of niobium to transition metal in the regenerated cathode material with orientation site-induced antiferromagnetic coupling is (0.005-0.02):

1.

3. The method for preparing the regenerated positive electrode material with orientation site-induced antiferromagnetic coupling as described in any one of claims 1-2, characterized in that, Includes the following steps: (1) Pretreatment of waste lithium nickel cobalt manganese oxide cathode material to obtain cathode material intermediate; (2) The cathode material intermediate, lithium source and niobium source are mixed to obtain the powder to be sintered; (3) The powder to be sintered is subjected to high-temperature calcination treatment, and after cooling, the regenerated positive electrode material with orientation site-induced antiferromagnetic coupling is obtained.

4. The preparation method according to claim 3, characterized in that, The pretreatment described in step (1) includes partial lithium replenishment and impurity removal.

5. The preparation method according to claim 4, characterized in that, The cathode material intermediate mentioned in step (1) is obtained by low-temperature molten salt pre-lithiation and cleaning and drying process.

6. The preparation method according to claim 5, characterized in that, Step (1) is as follows: Waste lithium nickel cobalt manganese oxide cathode material and low-temperature molten salt system were ground in an infrared lamp-assisted drying environment until they reached a homogeneous state, thus obtaining a mixture. The mixture was subjected to low-temperature calcination, cooled, washed and dried with water to obtain the cathode material intermediate.

7. The preparation method according to claim 6, characterized in that, The low-temperature molten salt system includes lithium hydroxide, lithium nitrate, and an organic lithium salt additive; the organic lithium salt additive is lithium benzoate; the mass ratio of lithium hydroxide, lithium nitrate, and lithium benzoate is 9.9:42.46:133.

49. And / or, the mass ratio of the waste nickel-cobalt-manganese lithium cathode material to the low-temperature molten salt system is 200:185.85; And / or, the low-temperature calcination temperature is 300°C, and the low-temperature calcination time is 4 hours.

8. The preparation method according to claim 3, characterized in that, The lithium source mentioned in step (2) is lithium carbonate; And / or, the niobium source is at least one of niobium pentoxide and ammonium oxalate hydrate; And / or, the mass ratio of the lithium source to the cathode material intermediate is (27.75-55.5):150; And / or, the mass ratio of the niobium source to the cathode material intermediate is (1-4):

150.

9. The preparation method according to claim 3, characterized in that, The high-temperature calcination temperature in step (3) is 800-900℃, and the high-temperature calcination time is 2-10h.

10. The application of the regenerated cathode material with orientation site-induced antiferromagnetic coupling as described in any one of claims 1-2 or the regenerated cathode material with orientation site-induced antiferromagnetic coupling prepared by the preparation method as described in any one of claims 3-9 in lithium-ion batteries.

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