Method for repairing three-dimensional structure of positive electrode material of waste lithium nickelate battery

Abstract

The invention provides a method for repairing a three-dimensional structure of a waste lithium nickelate battery positive electrode material, and relates to the technical field of secondary battery regeneration, and the method comprises the following steps: S1, crushing and screening the waste lithium nickelate battery positive electrode material, immersing the crushed and screened waste lithium nickelate battery positive electrode material into an acid solution, and filtering to obtain the acid-washed waste lithium nickelate battery positive electrode material; s2, adding organic lithium into the acid-washed positive electrode material of the waste lithium nickelate battery, and performing ball milling to obtain a first mixture; s3, performing segmented sintering on the first mixture in an oxygen atmosphere to obtain a second mixture; s4, introducing the second mixture into an aluminum source, and forming a gradient coating layer through atomic layer deposition; the waste lithium nickelate positive electrode material is subjected to acid treatment to dissolve Ni < 2 + > in a rock salt phase, organic lithium is added and is uniformly attached to the surface of the waste lithium nickelate positive electrode material through ball milling, and the lithium supplementing uniformity is ensured; lithium deficiency in crystal lattices is repaired through segmented calcination, and a layered structure is recovered; and an aluminum source is introduced to form a gradient coating layer by using an atomic deposition technology, so that the interface bonding stability is enhanced.

Description

Technical Field

[0001] The present application relates to the technical field of secondary battery regeneration, and in particular to a method for repairing the three-dimensional structure of a positive electrode material of a waste lithium nickel oxide battery. Background Art

[0002] As the global energy structure transitions toward a green and low-carbon future, lithium nickel oxide (LiNiO2) batteries, with their high specific capacity and low cost, have become a core power source for new energy vehicles, energy storage power stations, and other sectors. Lithium nickel oxide (LiNiO2) cathode materials have a theoretical specific capacity of 274 mAh / g, far exceeding that of traditional lithium cobalt oxide materials, and their market share has continued to rise in recent years. However, LiNiO2 batteries typically have a service life of only 5-8 years. If these used batteries are not effectively disposed of, not only will they waste critical resources such as lithium and nickel, but they will also pose a potential threat to the ecological environment due to residual fluoride electrolytes, organic carbonate solvents, and heavy metals in the cathode materials.

[0003] Therefore, it is of great significance to effectively recycle the positive electrode materials of waste lithium nickelate batteries. Currently, the recycling of waste lithium nickelate battery positive electrode materials faces multiple technical bottlenecks. In terms of structural stability, the Chinese patent publication number CN105870408A discloses a lithium-ion battery positive electrode material and its preparation method. During long-term charging and discharging, the lithium ions in the lithium nickelate lattice and the nickel ions are similar in radius (Li + Radius 0.76Å, Ni 2+ Radius 0.69Å), it is very easy to have cation mixing phenomenon, which leads to the collapse of the layered structure of the material and the blockage of the lithium ion diffusion channel. From the perspective of ion diffusion dynamics, such as the self-repairing polycrystalline positive electrode material and its preparation method disclosed in the Chinese patent application with publication number CN118136797A, during the cycle of waste positive electrode materials, the lattice repeatedly undergoes volume expansion and contraction caused by lithium insertion and extraction, resulting in microcracks at the grain boundaries, which hinder the efficiency of lithium ion transmission. These technical difficulties make it difficult for existing recycling processes to effectively restore the electrochemical properties of the material. There is an urgent need to develop a technology for repairing waste lithium nickel oxide battery positive electrode materials to achieve high-value recycling of waste lithium nickel oxide battery positive electrode materials. Summary of the Invention

[0004] In order to solve the above technical problems, the present application provides a method for repairing the three-dimensional structure of the positive electrode material of waste lithium nickel oxide batteries. First, the positive electrode material of waste lithium nickel oxide batteries is acid-washed and then organic lithium is added and mixed and ball-milled. Secondly, lithium is replenished through segmented sintering. Finally, the three-dimensional structure of the positive electrode material of waste lithium nickel oxide batteries is regenerated through an atomic layer deposition gradient coating process.

[0005] In order to achieve the above purpose, a technical solution adopted by the present invention is:

[0006] In a first aspect, the present application provides a method for repairing the three-dimensional structure of a waste lithium nickel oxide battery positive electrode material, comprising the following steps:

[0007] S1. After crushing and screening the waste lithium nickelate positive electrode material, immersing it in an acid solution and filtering it to obtain the acid-washed waste lithium nickelate positive electrode material;

[0008] S2, adding organic lithium to the waste lithium nickelate positive electrode material after pickling and ball milling to obtain a first mixture;

[0009] S3, sintering the first mixture in sections in an oxygen atmosphere to obtain a second mixture;

[0010] S4. The second mixture is introduced into an aluminum source to form a gradient coating layer by atomic layer deposition.

[0011] In this application, the waste lithium nickelate LiNiO2 cathode material forms an electrochemically inert rock salt phase (NiO) on the surface due to oxygen loss and transition metal (Ni) migration during the charge and discharge cycle. The waste lithium nickelate cathode material is treated with acid, and the acid solution (such as dilute sulfuric acid / citric acid) dissolves the Ni in the rock salt phase. 2+ , retaining the internal layered structure. The reaction formula is: NiO+2H + →Ni 2+ +H2O. At the same time, it dissolves impurities (such as Li2CO3, LiF, etc.) remaining in the electrolyte after surface charge and discharge cycles. Organic lithium and waste LiNiO2 positive electrode materials are evenly dispersed at the micron level through ball milling mechanical force, and organic lithium is evenly attached to the surface of waste LiNiO2 positive electrode materials through electrostatic adsorption to ensure the uniformity of lithium replenishment. The C-Li bond in organic lithium breaks at low temperatures and decomposes into lithium oxide. Lithium oxide melts at high temperatures to release Li+, thereby repairing the lithium deficiency in the lattice. At the same time, high temperature calcination makes Ni 2+ Oxidized to Ni 3+ , causing it to migrate from the Li layer (octahedral position) back to the transition metal layer, eliminating lattice distortion and restoring the layered structure. The high-temperature repaired lithium-containing mixture is then fed with an aluminum source precursor and other reaction gases, and deposited on the surface using atomic deposition technology. By precisely controlling the number of cycles or process parameters, a gradient coating with varying thickness or composition is formed. The gradient structure, due to the dense coating formed by aluminum oxide on the material surface, helps relieve stress between the coating and the main material, enhancing interfacial bonding stability.

[0012] Preferably, the waste lithium nickel oxide battery positive electrode material in S1 is crushed and sieved to a particle size of 5 to 50 μm.

[0013] Preferably, the acid solution in S1 includes at least one of oxalic acid, citric acid, malic acid and tartaric acid; the concentration of the acid solution is 0.1-2 mol / L; the mass ratio of the crushed and sieved waste lithium nickel oxide battery positive electrode material in S1 to the acid solution is 1: (5-20).

[0014] Preferably, the organic lithium in S2 includes at least one of lithium acetate, lithium propionate, lithium lactate and lithium acetate; and the mass ratio of the acid-washed waste lithium nickel oxide battery positive electrode material and the organic lithium in S2 is 1:(0.05-0.2).

[0015] Preferably, the ball milling speed in S2 is 200-600 r / min, and the time is 2-10 h; lithium phosphate with a mass fraction of 0.5-2 wt% is added as a grain boundary stabilizer during the ball milling process.

[0016] Preferably, the oxygen flow rate in S3 is 100-500 mL / min.

[0017] Preferably, the staged sintering in S3 includes a first stage sintering and a second stage sintering; the first stage sintering is to heat the temperature to 300-500°C at a heating rate of 5-20°C / min and keep it warm for 1-3 hours; the second stage sintering is to heat the temperature to 700-900°C at a heating rate of 3-10°C / min and keep it warm for 2-6 hours.

[0018] Preferably, the aluminum source includes at least one of trimethylaluminum, aluminum triisopropoxide and methylaluminoxane; the deposition temperature of the atomic layer deposition is 80-300°C, the number of deposition cycles is 50-500 times, and a single deposition step includes an aluminum source pulse, a first inert gas purge, an oxygen source pulse and a second inert gas purge.

[0019] Preferably, the gradient coating layer is aluminum oxide, aluminum hydroxide or lithium aluminate, the thickness of the gradient coating layer is 5-50 nm, and the gradient variation range of the aluminum content from the inside to the outside is 10%-90%.

[0020] Preferably, before S1, the method further includes a pretreatment step: disassembling the waste lithium battery, separating the positive electrode sheets, removing the current collector aluminum foil, and collecting the positive electrode active material; and after S4, a post-treatment step: screening the second mixture forming the gradient coating layer.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] This application provides a method for repairing the three-dimensional structure of waste lithium nickelate battery positive electrode materials. During the charge and discharge cycle, waste lithium nickelate positive electrode materials form an electrochemically inert rock salt phase (NiO) on the surface due to oxygen loss and transition metal (Ni) migration. The waste lithium nickelate positive electrode materials are treated with acid, and the acid solution dissolves the Ni² in the rock salt phase. + , retaining the internal layered structure. The reaction formula is: NiO+2H + →Ni 2+ +H2O. At the same time, it dissolves impurities (such as Li2CO3, LiF, etc.) remaining in the electrolyte after surface charge and discharge cycles. Organic lithium and waste LiNiO2 positive electrode materials are evenly dispersed at the micron level through ball milling mechanical force, and organic lithium is evenly attached to the surface of waste LiNiO2 positive electrode materials through electrostatic adsorption to ensure the uniformity of lithium replenishment. The C-Li bond in organic lithium breaks at low temperatures and decomposes into lithium oxide. Lithium oxide melts at high temperatures to release Li+, thereby repairing the lithium deficiency in the lattice. At the same time, high temperature calcination makes Ni 2+ Oxidized to Ni 3+ , causing it to migrate from the Li layer back to the transition metal layer, eliminating lattice distortion and restoring the layered structure, thereby achieving the regeneration of the three-dimensional structure of the positive electrode material of the waste lithium nickel oxide battery. The lithium-containing mixture after high-temperature repair is introduced into the aluminum source precursor and other reaction gases, and deposited on its surface using atomic deposition technology. By precisely controlling the number of cycles or process parameters, a gradient coating layer with gradual thickness or composition is formed. The gradient structure helps to relieve the stress between the coating layer and the main material and enhance the interface bonding stability because aluminum oxide forms a dense coating layer on the surface of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a process flow chart of a method for repairing the three-dimensional structure of the positive electrode material of waste lithium nickel oxide batteries;

[0024] Figure 2 The graph shows the cycle life of the batteries prepared in Example 1 and Comparative Examples 1-3. DETAILED DESCRIPTION

[0025] The following will be combined with the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the embodiments described below are only some of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0026] In this application, the terms used in this application are for the purpose of describing specific embodiments only and are not intended to be limiting of the application.

[0027] As used in this application, the singular forms "for," "or," "an," "any," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0028] In addition, if the terms "first" and "second" appear in this application, they are only used for descriptive purposes and should not be understood as indicating or implying relative importance.

[0029] Example 1

[0030] like Figure 1 As shown, this embodiment provides a method for repairing the three-dimensional structure of a waste lithium nickel oxide battery positive electrode material, comprising the following steps:

[0031] S1: Disassemble the used LiNiO2 power battery, separate the positive electrode sheets, remove the current collector aluminum foil, and collect the positive electrode material. Grind the positive electrode material to a particle size of 40 μm, sieve it through a 400-mesh sieve, and immerse it in a 0.6 mol / L citric acid solution. The mass ratio of the crushed and sieved used lithium nickel oxide battery positive electrode material to the citric acid solution is 1:5, and filter and dry it.

[0032] S2: adding lithium lactate to the acid-washed waste lithium nickel battery positive electrode material, ball milling at a rotation speed of 300 r / min for 3 hours, wherein the mass ratio of the acid-washed waste lithium nickel battery positive electrode material to lithium lactate is 1:0.1 to obtain a first mixture.

[0033] S3: The first mixture was placed in an oxygen atmosphere with an oxygen flow rate of 350 mL / min, first heated to 350° C., kept warm for 2 h, then heated to 850° C., kept warm for 3.5 h, and sintered in stages to obtain the second mixture.

[0034] S4: The second mixture is placed in a fluidized bed, vacuumed and heated to 220°C, and gradient coating is performed using trimethylaluminum as an aluminum source precursor and high-purity oxygen plasma as a reaction gas. The deposition cycle is 250 times. A single deposition step includes an aluminum source pulse, a first inert gas purge, an oxygen source pulse and a second inert gas purge to form an aluminum hydroxide gradient coating layer with a thickness of 25 nm and an aluminum element content gradient ranging from 20% to 80% from the inside to the outside. The second mixture forming the aluminum hydroxide gradient coating layer is screened to obtain a three-dimensionally repaired waste lithium nickel oxide battery positive electrode material.

[0035] Example 2

[0036] like Figure 1 As shown, this embodiment provides a method for repairing the three-dimensional structure of a waste lithium nickel oxide battery positive electrode material, comprising the following steps:

[0037] S1: Disassemble the used LiNiO2 power batteries, separate the positive electrode sheets, remove the current collector aluminum foil, and collect the positive electrode material. Grind the positive electrode material to a particle size of 50 μm, sieve it through a 300-mesh sieve, and immerse it in a 1.5 mol / L oxalic acid solution. The mass ratio of the crushed and sieved used lithium nickel oxide battery positive electrode material to the oxalic acid solution is 1:12, and filter and dry it.

[0038] S2: adding lithium acetate to the acid-washed waste lithium nickel battery positive electrode material, ball milling at a rotation speed of 600 r / min for 2 hours, wherein the mass ratio of the acid-washed waste lithium nickel battery positive electrode material to lithium acetate is 1:0.08 to obtain a first mixture.

[0039] S3: The first mixture is placed in an oxygen atmosphere with an oxygen flow rate of 250 mL / min, first heated to 500° C., kept warm for 2 hours, then heated to 850° C., kept warm for 4 hours, and sintered in stages to obtain the second mixture.

[0040] S4: The second mixture is placed in a fluidized bed, vacuumed and heated to 200°C, and gradient coating is performed using aluminum triisopropoxide as an aluminum source precursor and high-purity oxygen plasma as a reaction gas. The deposition cycle is 350 times. A single deposition step includes an aluminum source pulse, a first inert gas purge, an oxygen source pulse and a second inert gas purge to form an aluminum hydroxide gradient coating layer with a thickness of 35 nm and an aluminum element content gradient ranging from 18% to 82% from the inside to the outside. The second mixture forming the aluminum hydroxide gradient coating layer is screened to obtain a waste lithium nickelate battery positive electrode material after three-dimensional structure repair.

[0041] Example 3

[0042] like Figure 1 As shown, a method for repairing the three-dimensional structure of a waste lithium nickel oxide battery positive electrode material includes the following steps:

[0043] S1: Disassemble the used LiNiO2 power batteries, separate the positive electrode sheets, remove the current collector aluminum foil, and collect the positive electrode material. Grind the positive electrode material to a particle size of 35 μm, sieve it through a 300-mesh sieve, and immerse it in a 2 mol / L tartaric acid solution. The mass ratio of the crushed and sieved used lithium nickel oxide battery positive electrode material to the tartaric acid solution is 1:18, and filter and dry.

[0044] S2: adding lithium acetate to the acid-washed waste lithium nickelate battery positive electrode material, and ball milling at a rotation speed of 500 r / min for 5 hours, wherein the mass ratio of the acid-washed waste lithium nickelate battery positive electrode material to lithium acetate is 1:0.16, to obtain a first mixture.

[0045] S3: The first mixture is placed in an oxygen atmosphere with an oxygen flow rate of 450 mL / min, first heated to 470°C, kept warm for 2 hours, then heated to 880°C, kept warm for 4 hours, and sintered in stages to obtain a second mixture. S4: The second mixture is placed in a fluidized bed, evacuated and heated to 250°C, and gradient coating is performed using methylaluminoxane as an aluminum source precursor and high-purity oxygen plasma as a reaction gas. The deposition cycle is 450 times, and a single deposition step includes an aluminum source pulse, a first inert gas purge, an oxygen source pulse, and a second inert gas purge to form an aluminum hydroxide gradient coating layer with a thickness of 33 nm and an aluminum element content gradient ranging from 17% to 86% from the inside to the outside. The second mixture forming the aluminum hydroxide gradient coating layer is screened to obtain a three-dimensionally repaired waste lithium nickel oxide battery positive electrode material.

[0046] Comparative Example 1

[0047] This comparative example provides a method for repairing the three-dimensional structure of waste lithium nickelate battery positive electrode materials. The difference from Example 1 is that the comparative example adopts a traditional direct regeneration method, and the crushed and sieved waste lithium nickelate positive electrode materials are mixed with lithium carbonate Li2CO3. The mass ratio of the waste lithium nickelate battery positive electrode material to the lithium carbonate is 1:0.1. After ball milling at a rotation speed of 300 r / min for 3 hours, the temperature is raised to 850°C and sintered for 12 hours to obtain the waste lithium nickelate battery positive electrode material with a repaired three-dimensional structure. Compared with Example 1, there is no S1 pickling step and no S4 gradient coating step.

[0048] Comparative Example 2

[0049] This comparative example provides a method for repairing the three-dimensional structure of waste lithium nickel battery positive electrode materials. The difference from Example 1 is that in S1, after the waste lithium nickel battery positive electrode materials are crushed and screened, they are not immersed in a citric acid solution for pickling to obtain the waste lithium nickel battery positive electrode materials with repaired three-dimensional structure.

[0050] Comparative Example 3

[0051] This comparative example provides a method for repairing the three-dimensional structure of a positive electrode material of a waste lithium nickelate battery. The method differs from Example 1 in that a traditional impregnation method is used for coating in S4: the sintered second mixture is immersed in a 0.1 mol / L Al (NO3)3 solution, taken out after soaking for 12 hours, and sintered at 600°C for 2 hours. A uniform aluminum hydroxide coating layer is formed by a traditional impregnation method, replacing the atomic layer deposition in S4 of Example 1 to form an aluminum hydroxide gradient coating layer, thereby obtaining a waste lithium nickelate battery positive electrode material after three-dimensional structure repair.

[0052] Performance testing:

[0053] 1. Lithium Concentration Standard Deviation Test: Secondary ion mass spectrometry was used to analyze the lithium distribution of the repaired cathode materials from Examples 1-3 and Comparative Examples 1-3. Multiple areas of the material surface were examined, and the standard deviation of the lithium concentration was calculated to assess the uniformity of the lithium crystal distribution. A smaller standard deviation of lithium concentration indicates a more uniform lithium crystal distribution.

[0054] 2. Crystal Structure Integrity Test: X-ray diffraction (XRD) was used to analyze the crystal structure of the repaired cathode materials of Examples 1-3 and Comparative Examples 1-3. The crystal structure integrity was assessed by calculating the full width at half maximum (FWHM) of the main peak in the XRD patterns and estimating the crystallite size using the Scherrer equation. The symmetry and intensity of the peaks in the patterns were combined to assess the crystal structure integrity. Higher crystal structure integrity indicates greater structural stability. The test results are shown in Table 1.

[0055] 3. Initial Coulombic Efficiency Test: Coin-type batteries were fabricated using the repaired cathode materials from Examples 1-3 and Comparative Examples 1-3. Initial charge-discharge tests were conducted using a charge-discharge tester. The charging voltage range was 2.5-4.3 V, the charging current was 0.1 C, and the discharge current was also 0.1 C. Initial Coulombic Efficiency = Initial Discharge Capacity / Initial Charge Capacity × 100%.

[0056] 4. Cycle life test: Batteries assembled from the repaired positive electrode materials of Examples 1-3 and Comparative Examples 1-3 were cycled 100 times at a current density of 1C. The charge and discharge data were recorded every 10 cycles, and the capacity retention rate was calculated. The capacity retention rate and stability in long-term cycling were tested.

[0057] 5. Rate Performance Test: Batteries assembled from the repaired positive electrode materials of Examples 1-3 and Comparative Examples 1-3 were subjected to three charge-discharge cycles at a current density of 1C, three charge-discharge cycles at a current density of 5C, and three more charge-discharge cycles at a current density of 1C. The ratio of the discharge capacity at a current density of 5C to the discharge capacity at a current density of 1C was calculated as the rate performance indicator. A higher ratio indicates better performance at high rates. The test results are shown in Table 2.

[0058] Table 1 Results of lithium concentration standard deviation test and crystal structure integrity test for Examples 1-3 and Comparative Examples 1-3

[0059]

[0060] According to the data in Table 1, the embodiment group achieves efficient and uniform diffusion of lithium elements by acid washing and adding an organic lithium segmented sintering step. Acid washing removes impurities, exposes transition metal active sites, and retains the layered structure of lithium phosphate. On the one hand, the organic lithium segmented sintering provides sufficient lithium source for the positive electrode material, increases the concentration of free lithium ions, and improves the lattice repair of lithium ions in the lithium nickelate positive electrode material, thereby reducing the standard deviation of lithium concentration. The standard deviations of lithium concentrations in Examples 1-3 are 2.8%, 3.2%, and 3.5%, respectively, while the lowest in the comparative group is 6.1%. On the other hand, the segmented sintering step further promotes the homogenization of lithium elements and crystal reconstruction, eliminates lattice defects, and improves the integrity of the crystal structure (Examples 1-3 reach 85%, 83%, and 82%, respectively). Taking Example 1 as an example, by exposing the transition metal active sites after acid washing, the organic lithium segmented sintering makes the lithium element stably distributed in the lattice, effectively reduces the mixing of cations, and maintains the stability of the layered structure. Comparative Example 1 uses a traditional direct regeneration method, which has low lithium replenishment efficiency, resulting in a lithium concentration standard deviation of up to 8.7%. The crystal structure has only 65% integrity due to local stress caused by uneven lithium distribution. Comparative Example 2 does not use acid washing, which cannot remove the inert layer on the surface of the original waste material, and the transition metal active sites are not fully exposed. As a result, the lithium concentration standard deviation is 7.6%, and the crystal structure integrity is only 68%. Although Comparative Example 3 undergoes post-processing, the coating layer has poor density, and electrolyte penetration causes interfacial side reactions, resulting in insufficient early lithium distribution and structural repair. The standard deviation of lithium concentration is 6.1%, and the crystal structure integrity is 72%, which is still lower than the data disclosed in Examples 1-3.

[0061] Table 2 Test data of the first coulombic efficiency, cycle life and rate performance of Examples 1-3 and Comparative Examples 1-3

[0062]

[0063] like Figure 2As shown, it is a cycle life curve diagram of Example 1 and Comparative Examples 1-3. At the same time, according to the analysis in Table 2, the first coulombic efficiency of Examples 1-3 is 94.5%, 93.8%, and 92.7%, respectively, while the first coulombic efficiency of Comparative Example 2 without the acid washing process is 89.5%. In the embodiment, acid washing can dissolve residual impurities such as Li2CO3 and LiOH on the surface of the positive electrode material, reduce side reactions with the electrolyte during the first charge and discharge (such as the formation of impedance layers such as LiF), thereby improving the reversible capacity. In the 1C 100 cycle test, the stable crystal structure of lithium nickelate after repair reduces the structural changes and capacity loss during the charge and discharge process, so that the capacity retention rates of Examples 1-3 reach 92.3%, 90.1%, and 89.7%, respectively. Compared with Comparative Example 1, the traditional regeneration method is only 78.5%, and Comparative Example 2 without acid washing is only 75.2%. The presence of the gradient coating effectively isolates the electrolyte, buffers volume changes, reduces interfacial impedance, and improves the ion transmission efficiency of the material at high rates. Therefore, the 5C / 1C rate performance of Examples 1-3 is 85.2%, 82.7%, and 80.5%, respectively. Taking Example 1 as an example, the alumina gradient coating effectively inhibits the erosion of the electrolyte on the material during high-rate charge and discharge, maintains structural stability, and ensures rapid lithium ion transmission. Due to the uneven distribution of lithium in Comparative Example 1, some lithium ions cannot participate in the reaction during the first charge and discharge, and the rate performance is only 68.3%. Although there is some improvement in Comparative Example 3, the overall performance is still not as good as the embodiment, with a rate performance of 72.1%.

[0064] In summary, the embodiment group acid-washed the waste lithium nickel oxide battery positive electrode material and added organic lithium for mixed ball milling. Secondly, lithium was supplemented through staged sintering. Finally, the atomic layer deposition gradient coating process was used to systematically achieve the regeneration of waste lithium nickel oxide battery positive electrode material from lithium element supplementation, diffusion optimization, crystal structure repair to surface protection, showing performance advantages compared with the control example.

[0065] The above results show and describe the basic principles and main features of this application as well as the advantages of this application.

[0066] Those skilled in the art should understand that the present application is not limited to the above-described embodiments. The above-described embodiments and descriptions are merely illustrative of the principles of the present application. Various changes and improvements may be made to the present application without departing from the spirit and scope of the present application. Such changes and improvements are intended to fall within the scope of the present application. The scope of protection claimed in the present application is defined by the equivalents of the appended claims.

Claims

1. A method for repairing the three-dimensional structure of the positive electrode material of waste lithium nickel oxide batteries, characterized in that: The following steps are involved: S1, crushing and screening the waste lithium nickel acid battery positive electrode material, immersing it in an acid solution and filtering it to obtain the acid-washed waste lithium nickel acid battery positive electrode material; S2, adding organic lithium to the acid-washed waste lithium nickel oxide battery positive electrode material and ball milling to obtain a first mixture; S3, sintering the first mixture in sections in an oxygen atmosphere to obtain a second mixture; S4. The second mixture is introduced into an aluminum source to form a gradient coating layer by atomic layer deposition.

2. The method for repairing the three-dimensional structure of the positive electrode material of waste lithium nickel oxide batteries according to claim 1, characterized in that: The waste lithium nickel oxide battery positive electrode material in S1 is crushed and sieved to a particle size of 5 to 50 μm.

3. The method for repairing the three-dimensional structure of the positive electrode material of waste lithium nickel oxide batteries according to claim 1, characterized in that: The acid solution in S1 includes at least one of oxalic acid, citric acid, malic acid and tartaric acid; the concentration of the acid solution is 0.1-2 mol / L; the mass ratio of the crushed and sieved waste nickel-ion battery positive electrode material in S1 to the acid solution is 1:(5-20).

4. The method for repairing the three-dimensional structure of the positive electrode material of waste lithium nickel oxide batteries according to claim 1, characterized in that: The organic lithium in S2 includes at least one of lithium acetate, lithium propionate, lithium lactate and lithium acetate; the mass ratio of the acid-washed waste lithium nickelate battery positive electrode material and the organic lithium in S2 is 1: (0.05-0.2).

5. The method for repairing the three-dimensional structure of the positive electrode material of waste lithium nickel oxide batteries according to claim 1, characterized in that: The ball milling speed in S2 is 200-600 r / min, and the time is 2-10 h; lithium phosphate with a mass fraction of 0.5-2 wt% is added as a grain boundary stabilizer during the ball milling process.

6. The method for repairing the three-dimensional structure of the positive electrode material of waste lithium nickel oxide batteries according to claim 1, characterized in that: The oxygen flow rate in S3 is 100-500 mL / min.

7. The method for repairing the three-dimensional structure of the positive electrode material of waste lithium nickel oxide batteries according to claim 1, characterized in that: The staged sintering in S3 includes a first stage sintering and a second stage sintering; the first stage sintering is to heat up to 300-500°C at a heating rate of 5-20°C / min and keep warm for 1-3 hours; the second stage sintering is to heat up to 700-900°C at a heating rate of 3-10°C / min and keep warm for 2-6 hours.

8. The method for repairing the three-dimensional structure of the positive electrode material of waste lithium nickel oxide batteries according to claim 1, characterized in that: The aluminum source includes at least one of trimethylaluminum, aluminum triisopropoxide and methylaluminoxane; the deposition temperature of the atomic layer deposition is 80-300°C, the number of deposition cycles is 50-500 times, and a single deposition step includes an aluminum source pulse, a first inert gas purge, an oxygen source pulse and a second inert gas purge.

9. The method for repairing the three-dimensional structure of the positive electrode material of waste lithium nickel oxide batteries according to claim 1, characterized in that: The gradient coating layer is aluminum oxide, aluminum hydroxide or lithium aluminate, the thickness of the gradient coating layer is 5-50 nm, and the content of the aluminum element changes gradually from the inside to the outside in a range of 10%-90%.

10. The method for repairing the three-dimensional structure of the positive electrode material of waste lithium nickel oxide batteries according to claim 1, characterized in that: Before S1, the method further includes a pretreatment step: disassembling the waste lithium battery, separating the positive electrode sheets, removing the current collector aluminum foil, and collecting the positive electrode active material; and after S4, a post-treatment step: screening the second mixture that forms the gradient coating layer.

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