Method for repairing and regenerating ternary material interface of waste lithium battery

Abstract

The invention discloses a method for repairing and regenerating a ternary material interface of a waste lithium battery, and belongs to the technical field of recycling of fly-flow lithium ion batteries. The method comprises the following steps: carrying out heat treatment on a recycled waste ternary material to obtain a preliminarily purified ternary material; placing in a reducing solution, adding an alkali solution to adjust the pH value, and reacting; aging, washing and drying the reacted system, and sintering for the first time; and supplementing lithium and carrying out secondary sintering to obtain the regenerated ternary material. According to the method disclosed by the invention, a failed material interface can be remodeled into a precursor structure at a low temperature, and a new layered interface is formed through high-temperature lithium mixing sintering, so that high-quality regeneration of the failed ternary material is realized, and meanwhile, the regeneration cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of recycling of waste lithium-ion batteries, and particularly to a method for repairing and regenerating the interface of ternary materials of waste lithium batteries. Background Art

[0002] The ternary materials of waste lithium batteries contain important metal elements such as Li, Ni, Co, and Mn, and have high recycling and regeneration value. After the ternary materials are used, some active lithium is lost due to excessive film formation on the negative electrode, and at the same time, the material interface will be inactivated due to side reactions with the decomposed electrolyte. In addition, frequent lithium deintercalation and intercalation easily lead to Li / Ni mixing and lattice cracks, generating an interface layer that does not have lithium storage activity, resulting in a decrease in the material capacity. Therefore, at present, the recycled ternary materials are basically reused by wet leaching, and the metal elements are leached by strong acids such as sulfuric acid / hydrochloric acid and combined with oxidation-reduction agents to form metal salts. However, for ternary materials with a low degree of inactivation, there is only a mild failure of the interface structure, and the failure depth is dozens of nanometers, which has the feasibility of direct repair and regeneration. The wet treatment method has caused a certain degree of cost increase and resource waste.

[0003] At present, there are mainly three direct repair and regeneration methods. ① Solid-phase regeneration method: The missing elements are added to the waste ternary materials, and then high-temperature solid-phase sintering is carried out for element supplementation and structure repair. This regeneration method is simple, but the uniformity of the regenerated materials is poor, and the restoration effect of the layered structure is not good. ② Hydrothermal regeneration: The waste ternary is hydrothermally reacted with a high-concentration lithium hydroxide solution, and lithium is supplemented through high temperature and high pressure and concentration difference effects, and then high-temperature sintering is carried out for structure repair. This scheme requires a large amount of high-concentration lithium hydroxide, with high regeneration costs and low regeneration efficiency, and cannot be mass-produced. ③ Molten salt method regeneration: Two or more metal lithium salts are used to form a low-temperature eutectic system to provide a liquid-phase environment and substances for the reaction. Driven by the temperature field, specific ions in the positive electrode material are deintercalated or intercalated, and the crystal structure of the material is repaired and regenerated. This method also requires a large amount of lithium salts, with high repair costs. Therefore, it is urgent to develop a method for repairing and regenerating waste ternary materials with low cost and good effect to realize the comprehensive utilization of resources. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the present invention provides a method for repairing and regenerating the interface of ternary materials of waste lithium batteries. The method of the present invention can reshape the failed material interface into a precursor structure at low temperature, and form a new layered interface through high-temperature lithium mixing and sintering, realizing the high-quality regeneration of the failed ternary materials, and at the same time reducing the regeneration cost.

[0005] The technical solution of the present invention is as follows:

[0006] The first aspect of the present invention provides a method for repairing and regenerating the interface of ternary materials of waste lithium batteries, and the method comprises the following steps:

[0007] S1: Heat-treat the recycled waste ternary materials to obtain preliminarily purified ternary materials;

[0008] S2: Place the preliminarily purified ternary materials obtained in step S1 into a reducing solution to obtain a mixed solution, add an alkali solution to adjust the pH value, and react;

[0009] S3: After the reaction ends, age the system, then wash and dry the materials, and perform a primary sintering;

[0010] S4: Measure the lithium content of the sintered materials, and add lithium compound powders according to the stoichiometric ratio to perform a secondary sintering;

[0011] S5: Sort the materials obtained by sintering to obtain regenerated ternary materials.

[0012] In some embodiments, in step S1, the waste ternary materials are obtained by mechanical peeling and sorting of waste positive electrode sheets, the temperature of the heat treatment is 550 - 650 °C, the time is 1 - 3 h, and the atmosphere is oxygen or air.

[0013] In some embodiments, in step S2, the reducing solution is an alcohol reducing agent solution; the alcohol reducing agent solution is obtained by adding water to an alcohol reducing agent.

[0014] In some embodiments, the alcohol reducing agent includes at least one of methanol, ethanol, ethylene glycol, isopropanol, and benzyl alcohol;

[0015] In some embodiments, the mass proportion of the alcohol reducing agent in the alcohol reducing agent solution is 10 - 50%;

[0016] In some embodiments, the solid content of the mixed solution is 10 - 30%;

[0017] In some embodiments, in step S2, the alkali solution includes at least one of sodium hydroxide solution and potassium hydroxide solution;

[0018] In some embodiments, the concentration of the alkali solution is 2 - 3 mol / L;

[0019] Adjusting the pH value means adjusting the pH value to 11 - 13.

[0020] In some embodiments, in step S2, the temperature of the reaction is 40 - 120 °C, and the time is 20 - 120 min.

[0021] In some embodiments, in step S3, the aging time is 3 - 6 h.

[0022] In some embodiments, in step S3, the temperature of the primary sintering is 450 - 550 °C, and the time is 2 - 3 h.

[0023] In some embodiments, in step S4, the lithium-containing compound includes at least one of lithium carbonate and lithium hydroxide;

[0024] The temperature of the secondary sintering is 780 - 850 °C, and the time is 6 - 10 h.

[0025] The second aspect of the present invention provides a regenerated ternary material prepared by the method described in the first aspect above.

[0026] The beneficial technical effects of the present invention are as follows:

[0027] By subjecting the waste ternary powder to heat treatment and then reducing it with a weak reducing agent in an alkaline environment, the Ni 3+ / 4+ , Co 3+ , Mn 4+ on the material surface is reduced, and Ni / Co / Mn / (OH)2 is generated. It realizes the reshaping of the failed material interface into a precursor structure at low temperature, and then forms a new layered interface through operations such as sintering and lithium supplementation, achieving the quality regeneration of the failed ternary material.

[0028] In addition, due to the non-uniformity of the solid-liquid reaction and the different Ksp (standard solubility products) of nickel hydroxide, cobalt hydroxide, and manganese hydroxide, the elemental distribution of the generated precursor is non-uniform. Therefore, the present invention further precisely controls the alcohol-water ratio, reaction pH, reaction temperature, and reaction time to generate a dense and thin Ni / Co / Mn / (OH)2 nanolayer on the interface of the failed material, with the layer thickness being 5 - 20 nm. The dense nanolayer ensures the high tap density of the material, and the material is more likely to form a homogeneous solid solution during sintering. The new interface structure constructed after sintering is stable. After the regeneration of the failed ternary material, the performance is excellent, and the regeneration process does not require the consumption of a large amount of high-cost reagents, with a low regeneration cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is the SEM diagram of the material before and after regeneration in Example 1 of the present invention.

[0030] In the figure: a. The waste ternary material before treatment in Example 1; b. The regenerated ternary material obtained in Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] The present invention will be specifically described below in conjunction with the embodiments.

[0032] The method described in the present invention is applicable to the regeneration of NCM111, NCM523, and NCM622 ternary materials. Different from the direct solid-phase regeneration and hydrothermal regeneration methods, the method described in the present invention can re-convert the failed interface into a dense layered structure with a more uniform element distribution. The regenerated material has high quality, and the regeneration process does not require the consumption of a large amount of high-cost reagents, so the regeneration cost is low.

[0033] In the first aspect of the present invention, a method for repairing and regenerating the interface of ternary materials of waste lithium batteries is provided. The method includes the following steps:

[0034] S1: Heat-treat the recycled waste ternary materials to obtain preliminarily purified ternary materials;

[0035] S2: Place the preliminarily purified ternary materials obtained in step S1 in a reducing solution, add an alkaline solution to adjust the pH value, and react;

[0036] S3: After the reaction ends, age the system, then wash and dry the materials, and perform a primary sintering;

[0037] S4: Measure the lithium content of the sintered materials, and add lithium compound powders according to the stoichiometric ratio for secondary sintering;

[0038] S5: Sort the materials obtained by sintering to obtain regenerated ternary materials.

[0039] It can be understood that in the present invention, after heat-treating the waste ternary powder and reducing it with a weak reducing agent in an alkaline environment, Ni 3+ / 4+ , Co 3+ , Mn 4+ on the material surface are reduced to generate Ni / Co / Mn / (OH)2. The failed material interface is reshaped into a precursor structure at low temperature, and then sintered with lithium at high temperature to form a new layered interface, realizing the quality regeneration of the failed ternary materials.

[0040] In addition, due to the non-uniformity of the solid-liquid reaction and the different Ksp values of nickel, cobalt, and manganese hydroxides, the element distribution of the generated precursor is non-uniform. Therefore, the present invention further precisely controls the alcohol-water ratio, reaction pH, reaction temperature, and reaction time to generate a dense and thin Ni / Co / Mn / (OH)2 nanolayer on the failed material interface. The layer thickness is 5-20 nm. The dense nanolayer ensures the high tap density of the material, and the material is more likely to form a homogeneous solid solution during sintering. The new interface structure constructed after sintering is stable, and the performance of the failed ternary materials is excellent after regeneration.

[0041] In some embodiments, in step S1, the waste ternary material is obtained by peeling and sorting waste positive electrode sheets. The present invention does not limit the specific manner of peeling and sorting, and any peeling method that can achieve the present invention is within the protection scope of the present invention. Exemplarily, mechanical peeling and sorting can be used for the peeling and sorting to remove the positive electrode current collector and obtain the waste ternary material. It can be understood that the waste ternary material includes positive electrode active material, binder, conductive agent, electrolyte, etc.

[0042] In some embodiments, step S1 of the present invention is specifically: after the recovered waste ternary powder is screened by a sieve mesh, it is heat-treated at 500-650 °C for 1-3 h in an air or oxygen atmosphere to remove impurities such as aluminum, conductive agent, binder, and residual electrolyte mixed in the material.

[0043] It can be understood that the recovered waste ternary powder is a battery positive electrode material, including important metal elements such as lithium element, nickel element, cobalt element, and manganese element, and also contains metal aluminum chips, conductive agent, binder, residual electrolyte, etc. By sieving through a sieve mesh, impurities such as large-sized aluminum chips can be removed, and further through heat treatment, impurities such as conductive agent, binder, and residual electrolyte in the waste ternary powder will be removed.

[0044] In some embodiments, in step S1, the temperature of the heat treatment is 550-650 °C, including but not limited to 550 °C, 600 °C, 650 °C; the time is 1-3 h, including but not limited to 1 h, 2 h, 3 h; the atmosphere is oxygen or air.

[0045] In some embodiments, in step S2, the reducing solution is an alcohol reducing agent solution; the alcohol reducing agent solution is obtained by adding water to an alcohol reducing agent.

[0046] In some embodiments, in step S2, the alcohol reducing agent includes at least one of methanol, ethanol, ethylene glycol, isopropanol, and benzyl alcohol.

[0047] In some embodiments, the mass ratio of the alcohol reducing agent in the alcohol reducing agent solution is 10-50%, including but not limited to 10%, 20%, 30%, 40%, 50%.

[0048] It can be understood that in step S2, the preliminarily purified ternary material is immersed in the reducing solution to obtain a mixed solution, and after adjusting the pH with an alkali solution, a reduction reaction is carried out. Among them, the solid content of the mixed solution is 10-30%, including but not limited to 10%, 20%, 30%.

[0049] In some embodiments, in step S2, the alkali solution includes at least one of sodium hydroxide solution and potassium hydroxide solution.

[0050] In some embodiments, in step S2, the concentration of the alkali solution is 2 - 3 mol / L.

[0051] In some embodiments, in step S2, adjusting the pH value means adjusting the pH value to 11 - 13.

[0052] In some embodiments, in step S2, the temperature of the reaction is 40 - 120 °C, and the time is 20 - 120 min.

[0053] In step S2 of the present invention, by using alcohol as a reducing agent and sodium hydroxide to provide an alkaline environment, Ni on the material surface 3+ 、Ni 4+ 、Co 3+ 、Mn 4+ is reduced while Ni / Co / Mn / (OH)2 is generated.

[0054] The reducing agent used in the present invention has mild reducibility, is miscible with water, and its reducibility to metal ions is enhanced in an alkaline environment, and hydroxides are formed during reduction. If the pH or temperature of the reaction system is too high, the precipitation rate of Ni, Co, and Mn hydroxides will be too fast, resulting in a loose and non-dense product, and even causing the hydroxides to peel off, affecting the surface structure of the obtained regenerated material. When the temperature is too low and the pH is too low, the reaction cannot proceed.

[0055] It can be understood that in the present invention, by placing the ternary material preliminarily purified in step S1 in a reducing solution and adding an alkali-containing solution under pH monitoring, after the reaction, the failed interface can be transformed into a nanoscale nickel hydroxide / cobalt hydroxide / manganese hydroxide mixed solid solution layer, and the mixed layer is converted into a layered ternary material after lithium supplementation and sintering, realizing the quality regeneration of the failed interface.

[0056] In some embodiments, the thickness of the nickel / cobalt / manganese hydroxide layer after the transformation of the material failed interface is 5 - 20 nm, including but not limited to 5 nm, 10 nm, 15 nm, and 20 nm.

[0057] It can be understood that due to the inhomogeneity of the solid-liquid reaction and the different Ksp values of nickel hydroxide, cobalt hydroxide, and manganese hydroxide, the distribution of the precursor elements generated by the transformation will be inhomogeneous. Therefore, the present invention further precisely controls the alcohol-water ratio, reaction pH, reaction temperature, and reaction time to form a dense and thin Ni / Co / Mn / (OH)2 nanolayer at the interface of the failed material, with a layer thickness of 5 - 20 nm. The dense nanolayer ensures the high tap density of the material, and the material is more likely to form a homogeneous solid solution during sintering. The new interface structure constructed after sintering is stable, and the performance of the regenerated failed ternary material is excellent.

[0058] In some embodiments, in step S3, the aging time is 3 - 6 h, including but not limited to 3 h, 4 h, 5 h, and 6 h.

[0059] In some embodiments, in step S3, the temperature of the first sintering is 450 - 550 °C, including but not limited to 450 °C, 500 °C, and 550 °C, and the time is 2 - 3 h, including but not limited to 2 h, 2.5 h, and 3 h.

[0060] It can be understood that the hydroxide layer formed during aging will be denser. When sintered after drying, the hydroxide dehydrates to further form a dense metal oxide layer.

[0061] In some embodiments, in step S4, the lithium-containing compound includes at least one of lithium carbonate and lithium hydroxide.

[0062] In some embodiments, in step S4, the temperature of the second sintering is 780 - 850 °C, including but not limited to 780 °C, 800 °C, and 850 °C; the time is 6 - 10 h, including but not limited to 6 h, 7 h, 8 h, 9 h, and 10 h.

[0063] In some embodiments, in step S5, the sorting can be air-flow crushing and sorting of the obtained second-sintered material. The present invention does not limit the sorting method. The above is only an example of the present invention and should not be regarded as a limitation of the present invention's solution.

[0064] The second aspect of the present invention provides a regenerated ternary material prepared by the method described in the first aspect above.

[0065] The following are specific examples.

[0066] Example 1

[0067] A method for repairing and regenerating the interface of a ternary material of a waste lithium battery, comprising the following steps:

[0068] (1) Take waste NCM523 ternary powder (nickel-cobalt-manganese ternary powder), ultrasonically vibrate and sieve it through a 400-mesh sieve, and then heat-treat it at 600 °C for 2 h in an air atmosphere to obtain a preliminarily purified ternary material.

[0069] (2) Place the preliminarily purified ternary material in a mixed solution with a volume ratio of ethanol to water of 0.3:1, control the solid content of the solution at 20%, heat it to 100 °C, and slowly add a sodium hydroxide solution with a concentration of 2.5 mol / L to the system under stirring until the pH of the system is 12.0 ± 0.2, and react for 40 min.

[0070] (3) After the reaction, the temperature is lowered and aged for 3 h, then the material is filtered and washed with water until the pH = 7.5, dried, and then sintered at 450 °C for 3 h in an air atmosphere. Subsequently, the lithium content in the material is measured, and lithium carbonate fine powder is added for mixing according to the stoichiometric ratio, and then calcined at 800 °C for 6 h in an oxygen atmosphere.

[0071] (4) After the calcination, the particle size and specific surface area of the material are controlled by air flow crushing and sorting to obtain the recycled NCM523 material.

[0072] Example 2

[0073] A method for repairing and recycling the interface of ternary materials of waste lithium batteries, comprising the following steps:

[0074] (1) The waste NCM111 ternary powder is ultrasonically vibrated through a 400-mesh sieve and then treated at 500 °C in an oxygen atmosphere for 3 h to obtain a preliminarily purified ternary material.

[0075] (2) The preliminarily purified ternary material is placed in a mixed solution with a volume ratio of isopropanol to water of 0.4:1, the solid content of the solution is controlled at 30%, and after heating to 80 °C, a sodium hydroxide solution with a concentration of 2.0 mol / L is slowly added under stirring until the pH of the system is 12.6 ± 0.2, and the reaction is carried out for 30 min.

[0076] (3) After the reaction, the temperature is lowered and aged for 3.5 h, then the material is filtered and washed with water until the pH = 7.5, dried, and then sintered at 500 °C for 3 h in an air atmosphere. Subsequently, the lithium content in the material is measured, and lithium carbonate fine powder is added for mixing according to the stoichiometric ratio, and then calcined at 850 °C for 8 h in an oxygen atmosphere.

[0077] (4) After the calcination, the particle size and specific surface area of the material are controlled by air flow crushing and sorting to obtain the recycled NCM523 material.

[0078] Example 3

[0079] A method for repairing and recycling the interface of ternary materials of waste lithium batteries, comprising the following steps:

[0080] (1) The waste NCM622 ternary powder is ultrasonically vibrated through a 400-mesh sieve and then treated at 650 °C in an air atmosphere for 2 h to obtain a preliminarily purified ternary material.

[0081] (2) The preliminarily purified ternary material is placed in a mixed solution with a volume ratio of ethylene glycol to water of 0.1:1, the solid content of the solution is controlled at 10%, and after heating to 70 °C, a sodium hydroxide solution with a concentration of 3.0 mol / L is slowly added under stirring until the pH of the system is 12.5 ± 0.2, and the reaction is carried out at 70 °C for 100 min.

[0082] (3) After the reaction, the temperature was lowered and aged for 4 h, then the material was filtered and washed with water until the pH = 7.5, dried, and then sintered at 550 °C for 2 h in an air atmosphere. Subsequently, the lithium content in the material was measured, and lithium carbonate fine powder was added for mixing according to the stoichiometric ratio, and then calcined at 780 °C for 8 h in an oxygen atmosphere.

[0083] (4) After the calcination, the particle size and specific surface area of the material were controlled by air flow crushing and sorting to obtain the recycled NCM523 material.

[0084] Example 4

[0085] A method for repairing and recycling the interface of ternary materials of waste lithium batteries, comprising the following steps:

[0086] (1) The waste NCM523 ternary powder was ultrasonically sieved through a 400-mesh sieve and then treated at 600 °C in an oxygen atmosphere for 2 h to obtain a preliminarily purified ternary material.

[0087] (2) The preliminarily purified ternary material was placed in a mixed solution with a volume ratio of methanol to water of 0.2:1, and the solid content of the solution was controlled at 15%. After heating to 120 °C, a potassium hydroxide solution with a concentration of 2.2 mol / L was slowly added under stirring until the pH of the system was 12.4 ± 0.2, and the reaction was carried out at 120 °C for 20 min.

[0088] (3) After the reaction, the temperature was lowered and aged for 4 h, then the material was filtered and washed with water until the pH = 7.5, dried, and then sintered at 550 °C for 2 h in an air atmosphere. Subsequently, the lithium content in the material was measured, and lithium carbonate fine powder was added for mixing according to the stoichiometric ratio, and then calcined at 800 °C for 8 h in an oxygen atmosphere.

[0089] (4) After the calcination, the particle size and specific surface area of the material were controlled by air flow crushing and sorting to obtain the recycled NCM523 material.

[0090] Comparative Example 1

[0091] A method for repairing and recycling the interface of ternary materials of waste lithium batteries, comprising the following steps:

[0092] (1) The waste NCM523 ternary powder was ultrasonically sieved through a 400-mesh sieve and then heat-treated at 600 °C in an oxygen atmosphere for 1 h to obtain a preliminarily purified ternary material.

[0093] (2) The lithium element ratio in the material was measured, and lithium carbonate was added for sintering according to the stoichiometric ratio, and calcined at 800 °C for 8 h in an oxygen atmosphere.

[0094] (3) After the calcination, the material with a suitable particle size range was obtained by air flow crushing and sorting.

[0095] Comparative Example 2

[0096] It is basically the same as Example 1, except that in step (2), the pH of the solution system is adjusted to 14.

[0097] Comparative Example 3

[0098] It is basically the same as Example 1, except that in step (2), the heating-up and reaction temperature is 25 °C.

[0099] Comparative Example 4

[0100] It is basically the same as Example 1, except that in step (2), the ratio of ethanol to water is 0.05:1.

[0101] Comparative Example 5

[0102] It is basically the same as Example 1, except that, in contrast, in step (3), there is no primary sintering, and lithium supplementation sintering is directly carried out;

[0103] Step (3) is specifically as follows:

[0104] After the reaction is completed, the temperature is lowered and aged for 3 h, then the material is filtered, washed with water until the pH = 7.5, dried, then the lithium content in the material is tested, lithium carbonate fine powder is added for mixing according to the stoichiometric ratio, and then it is calcined at 800 °C for 6 h in an oxygen atmosphere.

[0105] Test Example:

[0106] (1) Material Characterization

[0107] Figure 1 This is the scanning electron microscope image of the material before and after regeneration in Example 1 of the present invention. As can be seen from the figure, the surface of the waste material before regeneration is rough and has many cracks, indicating that structural damage has occurred. After regeneration, the surface of the material is smooth and the boundaries are distinct.

[0108] (2) Element Distribution of the Regenerated Material and Performance Test of the Battery Prepared Therefrom

[0109] First, the element contents (expressed by the molar ratio of each element to Ni + Co + Mn) of the regenerated ternary materials prepared in the examples and comparative examples are measured by ICP, and the results are shown in Table 1.

[0110] Secondly, the regenerated ternary material prepared in the present invention is mixed with a binder and a conductive agent, then made into a slurry, coated, rolled, and cut. Then, a lithium sheet is used as the counter electrode to prepare a button battery. The battery is cycled twice at a rate of 0.1C, and the voltage range is 3.0 - 4.3V. Its specific capacity is measured, and the results are shown in Table 1.

[0111] The test method of capacity retention rate is: the prepared recycled ternary material is mixed with a binder and a conductive agent, and then slurried, coated, rolled, and cut, and then a graphite pole piece is used as a counter electrode to prepare a single-chip battery. The battery is cycled 500 times at a rate of 1C, room temperature, and a voltage range of 3.0-4.3V. The test results are shown in Table 1.

[0112] Table 1 Element distribution of recycled ternary materials of the embodiment and comparative example and performance test of batteries prepared therefrom

[0113]

[0114]

[0115] Note: In the table, "before regeneration" refers to the ternary material that has been initially purified after heat treatment in step (1); "once sintered" refers to the material before lithium supplementation after the first sintering in step (3); and "after regeneration" refers to the recycled material obtained in step (4).

[0116] It can be seen from Table 1 that: Comparative Example 1 directly performs solid-phase sintering repair. Although the capacity of the material is not low, its cycle performance is poor due to the uneven distribution of material elements after regeneration. At the same time, it can be seen from Comparative Example 1 and Comparative Examples 3-4 that for materials undergoing interface repair, too low a temperature and too little alcohol content will result in insufficient material reduction effect, and the regeneration effect is similar to direct solid-phase repair. It can be seen from Comparative Example 1 and Comparative Example 2 that when the reaction pH is too high, the material surface is quickly reduced to hydroxide, and excess hydroxide will be stripped into the solution, resulting in an imbalance in the element ratio of the material, and the density of the material after sintering is also low, resulting in a decrease in overall performance. In addition, it can be seen from Comparative Example 1 and Comparative Example 5 that the surface structure of the material that has not been sintered once will also be loose, and some particles will be stripped during direct lithium supplementation sintering to form fine particles, resulting in a decrease in the cycle performance of the material.

[0117] The above is only a preferred embodiment of the present invention, and the present invention is not limited to the above embodiments. It is understood that other improvements and changes directly derived or associated by those skilled in the art without departing from the spirit and concept of the present invention should be considered to be included in the protection scope of the present invention.

Claims

1. A method for repairing and regenerating the interface of ternary materials of waste lithium batteries, characterized in that, The method includes the following steps: S1: Heat-treat the recycled waste ternary material to obtain a preliminarily purified ternary material; S2: Place the ternary material preliminarily purified in step S1 into a reducing solution to obtain a mixed solution, add an alkali solution to adjust the pH value, and react; S3: After the reaction ends, age the system, then wash and dry the material, and perform a first sintering; S4: Measure the lithium content of the sintered material, add a lithium-containing compound powder according to the stoichiometric ratio, and perform a second sintering; S5: Sort the sintered material to obtain a recycled ternary material.

2. The method according to claim 1, wherein In step S1, the waste ternary material is obtained by mechanical peeling and sorting of waste positive electrode sheets. The temperature of the heat treatment is 550 - 650 °C, the time is 1 - 3 h, and the atmosphere is oxygen or air.

3. The method according to claim 1, wherein In step S2, the reducing solution is an alcohol reducing agent solution; the alcohol reducing agent solution is obtained by adding water to an alcohol reducing agent.

4. The method according to claim 3, wherein In step S2, the alcohol reducing agent includes at least one of methanol, ethanol, ethylene glycol, isopropanol, and benzyl alcohol; The mass percentage of the alcohol reducing agent in the alcohol reducing agent solution is 10 - 50%; The solid content of the mixed solution is 10 - 30%.

5. The method according to claim 1, wherein In step S2, the alkali solution includes at least one of a sodium hydroxide solution and a potassium hydroxide solution; Preferably, the concentration of the alkali solution is 2 - 3 mol / L; Adjusting the pH value means adjusting the pH value to 11 - 13.

6. The method according to claim 1, characterized in that In step S2, the temperature of the reaction is 40 - 120 °C, and the time is 20 - 120 min.

7. The method according to claim 1, characterized in that, In step S3, the aging time is 3 - 6 h.

8. The method according to claim 1, characterized in that, In step S3, the temperature of the first sintering is 450 - 550 °C, and the time is 2 - 3 h.

9. The method according to claim 1, characterized in that, In step S4, the lithium-containing compound includes at least one of lithium carbonate and lithium hydroxide; The temperature of the second sintering is 780 - 850 °C, and the time is 6 - 10 h.

10. A recycled ternary material prepared by the method according to any one of claims 1 - 9.

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