A method for repairing cracks in a positive electrode material precursor

Abstract

The present application relates to a kind of positive electrode material precursor crack repair method, the repair method includes the following steps: (1) coprecipitation reaction preparation positive electrode material precursor process, when the particle size of positive electrode material precursor reaches target particle size, the reaction system is stationary, then remove the supernatant after stratification, obtain the slurry to be repaired;(2) mixing basic solution with the slurry to be repaired described in step (1), then continue to mix thickener;(3) crack repair is carried out by heating.The repair method provided by the present application can repair the cracks on the surface of large particle size precursor and high nickel precursor, effectively improve the product qualification rate;Moreover, the repair method provided by the present application is simple to operate, easy for industrial conversion, and has good commercial prospects.

Description

Technical Field

[0001] This invention belongs to the field of battery material technology, and relates to a cathode material precursor, and more particularly to a method for repairing cracks in a cathode material precursor. Background Technology

[0002] Lithium-ion batteries have many advantages such as long cycle life, high safety performance and no memory effect, and are widely used in various mobile communication devices and electric vehicles. The improvement of lithium-ion battery performance largely depends on the continuous improvement of the performance of lithium battery cathode materials.

[0003] The cathode material of lithium-ion batteries is mainly formed by calcining a cathode material precursor with a lithium source. The performance of the cathode precursor directly affects the performance of the cathode material. However, if the particle size or nickel content is too high during the preparation of the cathode material precursor, the risk of cracks appearing on the surface of the cathode material precursor will increase.

[0004] Surface cracking of cathode material precursors can directly lead to the degradation of cathode material performance. Therefore, controlling surface cracking of cathode material precursors is very important for the development and industrial application of cathode material precursors.

[0005] CN114573053A discloses a dynamic repair method for a high-nickel ternary precursor with spherical cracks. The method includes: (1) preparing a mixed solution of Ni, Co, Mn and repair agent; preparing a precipitant and a complexing agent; (2) adding the repair agent to the reactor, adjusting the reaction temperature to 70-80℃, lowering the pH value by 0.2-0.25, and increasing the ammonia concentration by 0.1-0.15mol / L; (3) continuously adding the mixed solution, precipitant and complexing agent to the reactor at 50% of the original reaction flow rate, with the overflow flowing to the concentrator, and reacting for 6-10 hours; (4) stopping the liquid feeding after the repair is completed, and restoring the original reaction temperature, original pH value and original ammonia concentration; (5) restoring the original liquid feeding of metal, complexing agent and precipitant, and restoring the original flow rate; (6) pressing, filtering, washing and drying the slurry to obtain a high-nickel ternary precursor with a complete surface.

[0006] This method involves adjusting the process during the reaction to repair precursor cracks, but the timing of the repair is difficult to control, and there may be multiple cracking and repairs in a single reaction, affecting the production efficiency of the precursor.

[0007] CN111908517A discloses a method for preventing cracking during the synthesis of high-nickel ternary precursors. This method employs a segmented, batch process, mechanically mixing small and medium-sized precursor particles during the synthesis. The presence of particles of varying sizes buffers collisions within the reaction system, preventing cracking during synthesis. However, this method results in precursor particles with inconsistent sizes, and it can only prevent cracking. If cracks have already appeared on the precursor surface during the reaction, it cannot repair them.

[0008] Therefore, there is a need for a simple and effective method to repair cracks in cathode material precursors. Summary of the Invention

[0009] The purpose of this invention is to provide a method for repairing cracks in cathode material precursors. This method can repair cracks on the surface of large-particle-size precursors and high-nickel precursors, effectively improving the product qualification rate. Moreover, the repair method is simple to operate, easy to industrialize, and has good commercial prospects.

[0010] To achieve this objective, the present invention adopts the following technical solution:

[0011] This invention provides a method for repairing cracks in a cathode material precursor, the method comprising the following steps:

[0012] (1) In the process of preparing the cathode material precursor by coprecipitation reaction, when the particle size of the cathode material precursor reaches the target particle size, the reaction system is allowed to stand, and then the upper clear liquid after standing and stratification is removed to obtain the slurry to be repaired.

[0013] (2) Mix the alkaline solution with the slurry to be repaired described in step (1), and then continue mixing the thickener;

[0014] (3) Heating is used to repair cracks.

[0015] The repair method provided by this invention is used when cracks appear on the surface of the cathode material precursor. That is, when cracks are found on the surface of the cathode material precursor during the co-precipitation reaction to prepare the cathode material precursor, the reaction continues until the particle size of the cathode material precursor reaches the target particle size. Then, the feeding and stirring are stopped, and the reaction system is allowed to stand to achieve stratification, which facilitates the removal of the upper clear liquid after standing and stratification.

[0016] This invention first allows the reaction system to stand still, removing the supernatant and preventing unreacted molten metal from reacting with the subsequently added alkaline solution to form small particles or crystals, thus affecting the particle size uniformity of the precursor. After removing the supernatant, this invention further adds an alkaline solution, allowing hydroxide ions to enter the interlayer of the cathode material precursor. This increases the interlayer spacing of the precursor and allows the hydroxide ions to combine with the unreacted metal ions on the surface, thereby repairing cracks.

[0017] The present invention also increases the viscosity of the slurry by using a thickener, thereby reducing the probability of collision between precursor particles and the surrounding reaction environment and ensuring the repair effect of cracks.

[0018] Preferably, the target particle size in step (1) has a D50 value range of ≥8μm.

[0019] Preferably, the alkaline substance in the alkaline solution in step (2) is a sodium-containing alkaline substance.

[0020] Preferably, the alkaline substance in the alkaline solution in step (2) includes any one or a combination of at least two of sodium hydroxide, sodium carbonate, or sodium bicarbonate.

[0021] Preferably, the concentration of the alkaline solution in step (2) is 30 wt% to 40 wt%.

[0022] Preferably, the endpoint of the mixed alkaline solution in step (2) is to make the concentration of hydroxide ions in the system between 15 g / L and 40 g / L.

[0023] Preferably, the thickener in step (2) is a sodium-containing alkaline thickener.

[0024] Preferably, the thickener in step (2) includes any one or a combination of at least two of sodium carboxymethyl cellulose, sodium polyacrylate, or sodium alginate.

[0025] Preferably, the amount of thickener used in step (2) is 0.1 wt% to 1 wt% of the mass of the alkaline solution.

[0026] Preferably, the final temperature of the heating in step (3) is 60°C to 100°C.

[0027] Preferably, the crack repair in step (3) is carried out under stirring conditions.

[0028] Preferably, the stirring speed is 50 rpm to 150 rpm.

[0029] Preferably, the cathode material precursor in step (1) includes a nickel-cobalt-manganese hydroxide ternary precursor.

[0030] Preferably, based on the total molar amount of metal elements being 100%, the molar percentage of nickel in the cathode material precursor described in step (1) is 80% or more.

[0031] Preferably, the cathode material precursor in step (1) includes any one or a combination of at least two of the following: a nickel-cobalt-manganese hydroxide ternary precursor, a nickel-cobalt-aluminum ternary precursor, a nickel hydroxide precursor, or a nickel-manganese binary precursor.

[0032] As a preferred embodiment of the repair method provided by the present invention, the repair method includes the following steps:

[0033] (1) In the process of preparing the cathode material precursor by coprecipitation reaction, when the particle size of the cathode material precursor reaches the target particle size, the reaction system is allowed to stand, and then the upper clear liquid after standing and stratification is removed to obtain the slurry to be repaired.

[0034] (2) Mix an alkaline solution with a concentration of 30wt% to 40wt% with the slurry to be repaired described in step (1) to make the concentration of hydroxide ions in the system 15g / L to 40g / L, and then continue to mix the thickener; the amount of thickener is 0.1wt% to 1wt% of the mass of the alkaline solution.

[0035] (3) Heat the temperature to 60℃ to 100℃ and carry out crack repair under stirring conditions of 50rpm to 150rpm.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] This invention first allows the reaction system to stand still, removing the supernatant and preventing unreacted molten metal from reacting with the subsequently added alkaline solution to form small particles or crystals, thus affecting the particle size uniformity of the precursor. After removing the supernatant, this invention further adds an alkaline solution, allowing hydroxide ions to enter the interlayer of the cathode material precursor. This increases the interlayer spacing of the precursor and allows the hydroxide ions to combine with the unreacted metal ions on the surface, thereby repairing cracks. This invention also increases the viscosity of the slurry by using a thickener, thereby reducing the probability of collisions between precursor particles and the surrounding reaction environment, ensuring the crack repair effect. Attached Figure Description

[0038] Figure 1 This is a SEM image of the cathode material precursor before repair in Example 1;

[0039] Figure 2 This is a SEM image of the cathode material precursor after repair in Example 1;

[0040] Figure 3 This is a SEM image of the cathode material precursor before repair in Example 2;

[0041] Figure 4 This is a SEM image of the repaired cathode material precursor in Example 2. Detailed Implementation

[0042] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0043] An embodiment of the present invention provides a method for repairing cracks in a cathode material precursor, the method comprising the following steps:

[0044] (1) In the process of preparing the cathode material precursor by coprecipitation reaction, when the particle size of the cathode material precursor reaches the target particle size, the reaction system is allowed to stand, and then the upper clear liquid after standing and stratification is removed to obtain the slurry to be repaired.

[0045] (2) Mix the alkaline solution with the slurry to be repaired described in step (1), and then continue mixing the thickener;

[0046] (3) Heating is used to repair cracks.

[0047] The repair method provided by this invention is used when cracks appear on the surface of the cathode material precursor. That is, when cracks are found on the surface of the cathode material precursor during the co-precipitation reaction to prepare the cathode material precursor, the reaction continues until the particle size of the cathode material precursor reaches the target particle size. Then, the feeding and stirring are stopped, and the reaction system is allowed to stand to achieve stratification, which facilitates the removal of the upper clear liquid after standing and stratification.

[0048] This invention first allows the reaction system to stand still, removing the supernatant and preventing unreacted molten metal from reacting with the subsequently added alkaline solution to form small particles or crystals, thus affecting the particle size uniformity of the precursor. After removing the supernatant, this invention further adds an alkaline solution, allowing hydroxide ions to enter the interlayer of the cathode material precursor. This increases the interlayer spacing of the precursor and allows the hydroxide ions to combine with the unreacted metal ions on the surface, thereby repairing cracks.

[0049] The present invention also increases the viscosity of the slurry by using a thickener, thereby reducing the probability of collision between precursor particles and the surrounding reaction environment and ensuring the repair effect of cracks.

[0050] In some embodiments, the target particle size D50 in step (1) is greater than 8 μm, for example, it can be 8 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm or 15 μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0051] In some embodiments, the alkaline substance in the alkaline solution in step (2) is a sodium-containing alkaline substance.

[0052] In some embodiments, the alkaline substance in the alkaline solution of step (2) includes any one or a combination of at least two of sodium hydroxide, sodium carbonate, or sodium bicarbonate. Typical but non-limiting combinations include a combination of sodium hydroxide and sodium carbonate, a combination of sodium carbonate and sodium bicarbonate, a combination of sodium hydroxide and sodium bicarbonate, or a combination of sodium hydroxide, sodium carbonate, and sodium bicarbonate.

[0053] In some embodiments, when the alkaline substance in the alkaline solution in step (2) is sodium hydroxide, the concentration of the alkaline solution is 30wt% to 40wt%, for example, it can be 30wt%, 32wt%, 35wt%, 36wt%, 38wt% or 40wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0054] When the concentration of hydroxide ions in the system is too low, it cannot effectively repair the cracks on the surface of the cathode material precursor; while when the concentration of hydroxide ions in the system is too high, it will introduce too much sodium into the cathode material precursor, increasing the difficulty of subsequent washing and increasing the repair cost.

[0055] Therefore, as a preferred technical solution, the endpoint of the mixed alkaline solution in step (2) is to make the concentration of hydroxide ions in the system between 15 g / L and 40 g / L, for example, it can be 15 g / L, 20 g / L, 25 g / L, 30 g / L, 35 g / L or 40 g / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0056] In some embodiments, the thickener in step (2) is a sodium-containing alkaline thickener.

[0057] In some embodiments, the thickener in step (2) includes any one or a combination of at least two of sodium carboxymethyl cellulose, sodium polyacrylate, or sodium alginate. Typical but non-limiting combinations include a combination of sodium carboxymethyl cellulose and sodium polyacrylate, a combination of sodium polyacrylate and sodium alginate, a combination of sodium carboxymethyl cellulose and sodium alginate, or a combination of sodium carboxymethyl cellulose, sodium polyacrylate, and sodium alginate.

[0058] Too little thickener will not achieve a good thickening effect, but too much thickener will result in excessive organic impurities, affecting the performance of subsequent cathode materials.

[0059] Therefore, as a preferred technical solution, the amount of thickener used in step (2) is 0.1wt% to 1wt% of the mass of the alkaline solution, for example, it can be 0.1wt%, 0.3wt%, 0.5wt%, 0.6wt%, 0.8wt% or 1wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0060] In some embodiments, the endpoint temperature of the heating in step (3) is 60°C to 100°C, for example, it can be 60°C, 70°C, 80°C, 90°C or 100°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0061] The crack repair of the present invention is carried out at a temperature of 60°C to 100°C. The lower the temperature, the longer the repair time is required; the higher the temperature, the higher the energy consumption is required. Taking into account the repair efficiency and repair cost, the endpoint temperature of the heating in step (3) is preferably 60°C to 100°C.

[0062] In some embodiments, the crack repair in step (3) is performed under stirring conditions.

[0063] In some embodiments, the stirring speed is from 50 rpm to 150 rpm, for example, it can be 50 rpm, 100 rpm, 110 rpm, 120 rpm, 130 rpm, 140 rpm or 150 rpm, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0064] A faster stirring speed is beneficial for improving crack repair efficiency, but considering the repair effect, the stirring speed should be controlled and not too fast. Taking into account both the repair effect and the repair cost, the optimal stirring speed is 50 rpm to 150 rpm.

[0065] In some embodiments, the cathode material precursor in step (1) includes a nickel-cobalt-manganese hydroxide ternary precursor.

[0066] In some embodiments, with the total molar amount of metal elements being 100%, the molar percentage of nickel in the cathode material precursor described in step (1) is 80% or more, for example, it can be 80%, 82%, 85%, 88%, 90% or 95%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0067] In some embodiments, the cathode material precursor includes any one or a combination of at least two of the following: a nickel-cobalt-manganese hydroxide ternary precursor, a nickel-cobalt-aluminum ternary precursor, a nickel hydroxide precursor, or a nickel-manganese binary precursor. Typical but non-limiting combinations include a combination of a nickel-cobalt-manganese hydroxide ternary precursor and a nickel-cobalt-aluminum ternary precursor, a combination of a nickel hydroxide precursor and a nickel-manganese binary precursor, a combination of a nickel-cobalt-manganese hydroxide ternary precursor, a nickel-cobalt-aluminum ternary precursor and a nickel hydroxide precursor, or a combination of a nickel-cobalt-manganese hydroxide ternary precursor, a nickel-cobalt-aluminum ternary precursor, a nickel hydroxide precursor and a nickel-manganese binary precursor.

[0068] As a preferred embodiment of the repair method provided by the present invention, the repair method includes the following steps:

[0069] (1) In the process of preparing the cathode material precursor by coprecipitation reaction, when the particle size of the cathode material precursor reaches the target particle size, the reaction system is allowed to stand, and then the upper clear liquid after standing and stratification is removed to obtain the slurry to be repaired.

[0070] (2) Mix an alkaline solution with a concentration of 30wt% to 40wt% with the slurry to be repaired described in step (1) to make the concentration of hydroxide ions in the system 15g / L to 40g / L, and then continue to mix the thickener; the amount of thickener is 0.1wt% to 1wt% of the mass of the alkaline solution.

[0071] (3) Heat the temperature to 60℃ to 100℃ and carry out crack repair under stirring conditions of 50rpm to 150rpm.

[0072] Example 1

[0073] This embodiment provides a method for repairing cracks in a cathode material precursor. The cathode material precursor is a nickel-cobalt-manganese hydroxide ternary precursor with a molar ratio of Ni, Co, and Mn of 90:5:5. The repair method includes the following steps:

[0074] (1) In the reactor, when the particle size of the positive electrode material precursor reaches the target particle size D50 of 12 μm (surface defects such as...) Figure 1 (As shown), stop feeding and turn off stirring, let the reaction system stand until it separates into layers, and then remove the upper clear liquid after standing and separating to obtain the slurry to be repaired;

[0075] (2) Add a 35wt% sodium hydroxide solution to the reactor to make the concentration of hydroxide ions in the system 25g / L, and then continue to add sodium carboxymethyl cellulose as a thickener to the reactor; the amount of thickener is 0.5wt% of the mass of the alkaline solution.

[0076] (3) Heat to 80℃ and perform crack repair under stirring at 100 rpm. Stop the reaction after the surface cracks of the cathode material precursor disappear (SEM image of the repaired material is shown below). Figure 2 (As shown).

[0077] Depend on Figure 1 and Figure 2 The comparison shows that the surface cracks of the repaired cathode material precursor have basically disappeared, indicating that the repair method provided in this embodiment has a good crack repair effect.

[0078] Example 2

[0079] This embodiment provides a method for repairing cracks in a cathode material precursor. The cathode material precursor is a nickel-cobalt-aluminum hydroxide ternary precursor with a molar ratio of Ni, Co, and Al of 90:5:5. The repair method includes the following steps:

[0080] (1) In the reactor, when the particle size of the positive electrode material precursor reaches the target particle size D50 of 15 μm (surface defects such as...) Figure 3 (As shown), stop feeding and turn off stirring, let the reaction system stand until it separates into layers, and then remove the upper clear liquid after standing and separating to obtain the slurry to be repaired;

[0081] (2) Add a 30wt% sodium hydroxide solution to the reactor to make the concentration of hydroxide ions in the system 15g / L, and then continue to add sodium polyacrylate thickener to the reactor; the amount of thickener is 0.1wt% of the mass of the alkaline solution.

[0082] (3) Heat to 60℃ and perform crack repair under stirring at 150 rpm. Stop the reaction after the surface cracks of the cathode material precursor disappear (SEM image of the repaired material is shown below). Figure 4 (As shown).

[0083] Depend on Figure 3 and Figure 4 The comparison shows that the surface cracks of the repaired cathode material precursor have basically disappeared, indicating that the repair method provided in this embodiment has a good crack repair effect.

[0084] Example 3

[0085] This embodiment provides a method for repairing cracks in a cathode material precursor. Except for changing the amount of sodium hydroxide solution added in step (2) to make the concentration of hydroxide ions in the system 15 g / L, the rest is the same as in Example 1.

[0086] Example 4

[0087] This embodiment provides a method for repairing cracks in a cathode material precursor. Except for changing the amount of sodium hydroxide solution added in step (2) to make the concentration of hydroxide ions in the system 40 g / L, the rest is the same as in Example 1.

[0088] Example 5

[0089] This embodiment provides a method for repairing cracks in a cathode material precursor. Except for the fact that the crack repair in step (3) is carried out at 100°C, the rest is the same as in embodiment 1.

[0090] Example 6

[0091] This embodiment provides a method for repairing cracks in a cathode material precursor. Except for the crack repair in step (3), which is carried out at 60°C, the rest is the same as in embodiment 1.

[0092] Example 7

[0093] This embodiment provides a method for repairing cracks in a cathode material precursor. Except for the crack repair in step (3), which is carried out at a stirring speed of 50 rpm, the rest is the same as in embodiment 1.

[0094] Example 8

[0095] This embodiment provides a method for repairing cracks in a cathode material precursor. Except for the crack repair in step (3), which is carried out at a stirring speed of 150 rpm, the rest is the same as in embodiment 1.

[0096] Comparative Example 1

[0097] This comparative example provides a method for repairing cracks in a cathode material precursor, which is the same as in Example 1. The repair method includes the following steps:

[0098] (1) In the reactor, when the particle size of the positive electrode material precursor reaches the target particle size D50, which is the same as in Example 1, the feeding is stopped and the stirring is turned off. The reaction system is allowed to stand until it separates into layers. Then the upper clear liquid after standing and separating is removed to obtain the slurry to be repaired.

[0099] (2) The temperature was raised to 80°C and the crack was repaired under the stirring condition of 120 rpm. The crack repair time was the same as in Example 1.

[0100] In this invention, the time required for crack repair is used to evaluate the crack repair effect. Table 1 shows the time required for crack repair in Examples 1-8 and Comparative Example 1. The spherical cracking rate refers to the ratio of the number of cracked precursors observed under a 1000x scanning electron microscope to the total number of precursors. In this invention, repair is considered complete when the spherical cracking rate of the precursor is no greater than 2%.

[0101] Table 1

[0102]

[0103]

[0104] As can be seen from Examples 1 and 2, this method has a good crack repair effect on both NCM and NCA ternary precursors.

[0105] As can be seen from Examples 1, 3, and 4, the lower the concentration of hydroxide ions in the system, the longer the repair time is required; the higher the concentration of hydroxide ions in the system, the shorter the repair time; and the repair of cathode material precursor cracks can be achieved when the concentration of hydroxide ions in the system is in the range of 15 g / L to 40 g / L.

[0106] As can be seen from Examples 1, 5, and 6, the lower the temperature for crack repair, the longer the repair time; the higher the temperature for crack repair, the shorter the repair time, but the higher the energy consumption. When selecting the repair temperature, both repair efficiency and repair cost need to be considered. Crack repair of cathode material precursors can be achieved within the temperature range of 60℃ to 100℃.

[0107] As can be seen from Examples 1, 7, and 8, increasing the stirring speed for crack repair is beneficial to improving the crack repair efficiency; within the range of 50 rpm to 150 rpm for crack repair, the repair of cracks in the cathode material precursor can be achieved.

[0108] As can be seen from the comparison between Example 1 and Comparative Example 1, without a suitable alkali solution and thickener, the crack repair effect cannot be achieved.

[0109] In summary, this invention first allows the reaction system to stand still, removing the supernatant and preventing unreacted molten metal from reacting with the subsequently added alkaline solution to form small particles or crystals, thus affecting the particle size uniformity of the precursor. After removing the supernatant, this invention further adds an alkaline solution, allowing hydroxide ions to enter the interlayer of the cathode material precursor. This increases the interlayer spacing of the precursor and allows hydroxide ions to combine with unreacted metal ions on the surface, thereby repairing cracks. Furthermore, this invention increases the viscosity of the slurry by using a thickener, reducing the probability of collisions between precursor particles and the surrounding reaction environment, ensuring the crack repair effect.

[0110] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for repairing cracks in a cathode material precursor, characterized in that, The repair method includes the following steps: (1) In the process of preparing the cathode material precursor by coprecipitation reaction, when the particle size of the cathode material precursor reaches the target particle size, the reaction system is allowed to stand, and then the upper clear liquid after standing and stratification is removed to obtain the slurry to be repaired. (2) Mix the alkaline solution with the slurry to be repaired described in step (1), and then continue mixing the thickener; The alkaline substance in the alkaline solution includes any one or a combination of at least two of sodium hydroxide, sodium carbonate, or sodium bicarbonate. The endpoint of the mixed alkaline solution is to achieve a hydroxide ion concentration of 15 g / L to 40 g / L in the system; the amount of the thickener is 0.1 wt% to 1 wt% of the mass of the alkaline solution. (3) Heating is used to repair cracks.

2. The repair method according to claim 1, characterized in that, The target particle size in step (1) is D50 with a value range of ≥8μm.

3. The repair method according to claim 1, characterized in that, The concentration of the alkaline solution in step (2) is 30 wt% to 40 wt%.

4. The repair method according to claim 1, characterized in that, The thickener mentioned in step (2) is a sodium-containing alkaline thickener.

5. The repair method according to claim 1, characterized in that, The thickener in step (2) includes any one or a combination of at least two of sodium carboxymethyl cellulose, sodium polyacrylate, or sodium alginate.

6. The repair method according to claim 1, characterized in that, The final temperature of the heating in step (3) is 60°C to 100°C.

7. The repair method according to claim 1, characterized in that, The crack repair in step (3) is carried out under stirring conditions.

8. The repair method according to claim 7, characterized in that, The stirring speed is 50 rpm to 150 rpm.

9. The repair method according to claim 1, characterized in that, With the total molar amount of metal elements being 100%, the molar percentage of nickel in the cathode material precursor described in step (1) is more than 80%.

10. The repair method according to claim 9, characterized in that, The cathode material precursor in step (1) includes any one or a combination of at least two of the following: nickel-cobalt-manganese hydroxide ternary precursor, nickel-cobalt-aluminum ternary precursor, nickel hydroxide precursor, or nickel-manganese binary precursor.

11. The repair method according to claim 1, characterized in that, The repair method includes the following steps: (1) In the process of preparing the cathode material precursor by coprecipitation reaction, when the particle size of the cathode material precursor reaches the target particle size, the reaction system is allowed to stand, and then the upper clear liquid after standing and stratification is removed to obtain the slurry to be repaired. (2) Mix an alkaline solution with a concentration of 30wt% to 40wt% with the slurry to be repaired described in step (1) to make the concentration of hydroxide ions in the system 15g / L to 40g / L, and then continue to mix the thickener; the amount of thickener is 0.1wt% to 1wt% of the mass of the alkaline solution; (3) Heat the temperature to 60°C to 100°C and carry out crack repair under stirring conditions of 50 rpm to 150 rpm.

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