A ternary positive electrode material precursor and preparation method thereof

Abstract

A method for preparing a ternary positive electrode material precursor comprises the following steps: during the coprecipitation process, when the particles in the reactor grow to 65% to 75% of the target particle size, the feed rate of the additive solution is increased by 20% to 50%, the inert protective gas is stopped, and an oxidant is introduced to continue the reaction; when the particle size D50 in the reactor grows to 85% to 95% of the target particle size, the metal salt solution and oxidant are stopped, the additive solution is continued, the reactor temperature is increased, the stirring rate is reduced, the ammonia value is increased, and the pH value is reduced, and the reaction is maintained for 6 to 8 hours; the reactor conditions are then restored to the initial conditions, the reaction is continued, and the target particle size is reached, at which point the feed is stopped. The present invention prevents the cracking of large precursor particles by adding an anti-spherical cracking additive during the preparation of the ternary precursor, avoiding spherical cracking caused by collisions between particles in the late stage of the precursor reaction, thereby ensuring its cyclicity, stability, and safety.

Description

Technical Field

[0001] The present invention relates to a ternary cathode material precursor, in particular to a ternary cathode material precursor and a preparation method thereof. Background Art

[0002] As one of the main sources of new energy, lithium-ion batteries have attracted widespread attention due to their advantages such as small size, high capacity and low price. Among the many components that affect the performance of lithium-ion batteries, the positive electrode material that constitutes the battery is the most critical factor affecting the performance and application of secondary batteries. Due to its high energy density, relatively low cost and excellent cycle performance, ternary positive electrode materials are the most promising and promising materials among the currently mass-produced positive electrode materials. Therefore, improving the performance of ternary precursors is urgent. The production of ternary positive electrode material precursors mainly adopts the hydroxide co-precipitation process, which is to dissolve the raw materials in deionized water, mix them according to a certain molar ratio, and use NaOH as a precipitant and ammonia water as a complexing agent to produce a high-density spherical hydroxide precursor.

[0003] When preparing ternary precursors by the co-precipitation method, the production of high-nickel ternary precursors (nickel content ≥ 60%) is mostly prepared under high ammonia, high speed, and high pH conditions. Under the reaction conditions of high ammonia, high speed, and high pH, ​​with the continuous growth of particles and the continuous increase in the solid content of the reaction system, the collision between particles intensifies, which can easily lead to cracking of large precursor particles. The spherical cracking of the ternary precursor will cause the capacity of the prepared positive electrode material to decay, resulting in a decrease in electrochemical performance, reduced product quality, and seriously affecting the performance of the battery material. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for preparing a ternary cathode material precursor, which can prevent spherical cracking caused by collision between particles during the preparation process of the ternary cathode material precursor.

[0005] The technical solution adopted by the present invention to solve the technical problem is: a method for preparing a ternary positive electrode material precursor, comprising the following steps:

[0006] (1) preparing a metal salt solution, a complexing agent solution, a precipitant solution, and an additive solution, wherein the metal salt solution is an aqueous solution containing nickel salt, cobalt salt, manganese salt, or aluminum salt, and the additive solution is an aqueous solution of at least one of polyethylene glycol, polyvinyl alcohol, and polyacrylamide and gelatin;

[0007] (2) adding water, complexing agent solution, and precipitant solution into a reaction kettle, stirring, and maintaining constant temperature to prepare a reaction kettle bottom solution;

[0008] (3) adding a metal salt solution, an additive solution, a precipitant solution, and a complexing agent solution into a constant temperature reactor to carry out a coprecipitation reaction, and continuously passing an inert protective gas into the reactor during the reaction;

[0009] (4) When the particle size D50 in the reactor grows to 65% to 75% of the target particle size, the feed rate of the additive solution is increased by 20% to 50% compared with the feed rate in step (3), the inert protective gas is stopped, and the oxidant is introduced to continue the reaction;

[0010] (5) When the particle size D50 in the reactor grows to 85% to 95% of the target particle size, stop adding the metal salt solution and the oxidant, continue to add the additive solution, increase the reactor temperature by 20% to 50% compared with the reactor temperature in step (3), reduce the stirring rate by 20% to 30% compared with that in step (3), increase the ammonia value by 1 to 4 g / L compared with that in step (3), and reduce the pH value by 0.1 to 0.3 compared with that in step (3), and maintain the reaction for 6 to 8 hours;

[0011] (6) The temperature, pH value, stirring rate, ammonia value, and feeding rate of the reaction kettle are then restored to the reaction conditions of step (3), and the reaction is continued until the particle size D50 grows to the target particle size, and the feeding is stopped to obtain a solution containing the precursor material;

[0012] (7) The solution containing the precursor material obtained in step (6) is aged, washed, dried, screened, and iron removed to obtain a ternary positive electrode material precursor.

[0013] Furthermore, the oxidant is hydrogen peroxide, the mass concentration of hydrogen peroxide is 20% to 40%, and the oxidant is introduced to control the dissolved oxygen content of the solution in the reactor to be 15 to 30 mg / L.

[0014] Furthermore, the total concentration of metal ions in the metal salt solution is 1 to 3 mol / L, and the metal salt solution is an aqueous solution containing nickel salt, cobalt salt and manganese salt, wherein the molar percentage of nickel ions in the metal salt solution is 60% to 100% of the total metal ions, the molar percentage of cobalt ions in the total metal ions is 0% to 40%, and the molar percentage of manganese in the total metal ions is 0% to 40%.

[0015] Furthermore, the metal salt solution includes a nickel-cobalt salt solution and an aluminum salt solution, the total concentration of metal ions in the nickel-cobalt salt solution is 1 to 2.5 mol / L, the molar ratio of nickel salt to cobalt salt in the nickel-cobalt salt solution is 0.6 to 1:0 to 0.4, the concentration of aluminum in the aluminum salt solution is 0.05 to 0.3 mol / L, the introduction rate of the nickel-cobalt salt solution is 2 to 10 L / h, and the introduction rate of the aluminum salt solution is 0.5 to 4 L / h.

[0016] Furthermore, in step (3), the pH value of the reaction system is controlled to be 10.0-12.5, the ammonia value is 2-20 g / L, the temperature is 40-80° C., the stirring rate is 100-1000 rpm, and the introduction rate of the metal salt solution is 1-15 L / h.

[0017] Furthermore, the additive solution is an aqueous solution of at least one of polyethylene glycol, polyvinyl alcohol, and polyacrylamide and gelatin, the total mass concentration of polyethylene glycol, polyvinyl alcohol, and polyacrylamide in the additive solution is 0-2.0%, and the mass concentration of gelatin is 0.1-1.0%; the feed rate of the additive solution is 0-1.0 L / h.

[0018] Furthermore, the inert protective gas is nitrogen.

[0019] Furthermore, the precipitant solution is a sodium hydroxide solution with a mass concentration of 28% to 34%, and the complexing agent solution is an ammonia solution with a mass concentration of 16% to 25%.

[0020] Furthermore, the target particle size of the precursor material particles is 6 to 11 μm.

[0021] A ternary positive electrode material precursor prepared by the preparation method of a ternary positive electrode material precursor described in any one of the above.

[0022] The beneficial effects of the present invention are as follows: by adding an anti-ball cracking additive during the preparation of the ternary precursor and controlling different pH values, ammonia values, feed rates, etc. at different stages, the present invention prevents the cracking of large precursor particles and avoids ball cracking due to collisions between particles in the later stage of the precursor reaction, thereby ensuring its circulativity, stability and safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a reaction electron microscope image of the ternary cathode material precursor of Example 1 of the present invention;

[0024] Figure 2 This is an aging electron microscope image of the ternary cathode material precursor of Example 1 of the present invention;

[0025] Figure 3 This is a reaction electron microscope image of the ternary cathode material precursor of Comparative Example 1 of the present invention;

[0026] Figure 4 This is an aging electron microscope image of the ternary cathode material precursor of Comparative Example 1 of the present invention;

[0027] Figure 5 This is a reaction electron microscope image of the ternary cathode material precursor of Comparative Example 2 of the present invention;

[0028] Figure 6This is an aging electron microscope image of the ternary cathode material precursor of Comparative Example 2 of the present invention;

[0029] Figure 7 This is a reaction electron microscope image of the ternary cathode material precursor of Comparative Example 3 of the present invention;

[0030] Figure 8 This is an electron microscope image of the aging of the ternary positive electrode material precursor of Comparative Example 3 of the present invention. DETAILED DESCRIPTION

[0031] The present invention will be further described below with reference to the accompanying drawings and examples.

[0032] Example 1:

[0033] (1) preparing a nickel-cobalt-aluminum salt solution with a total concentration of 115 g / L, wherein the molar ratio of nickel-cobalt-aluminum is 8:1:1, and preparing an additive solution at 60° C., wherein the additive solution is a mixed aqueous solution containing 0.1% polyvinyl alcohol, 1% polyethylene oxide, and 0.1% gelatin, a sodium hydroxide solution with a mass percentage concentration of 32%, and an ammonia solution with a mass percentage concentration of 16%;

[0034] (2) Add pure water to the reactor until the liquid level reaches 50%, control the temperature at 60±1°C, introduce nitrogen as a protective gas, and adjust the pH to 11.70±0.05 and the ammonia concentration to 6.0±0.5 g / L using 32% sodium hydroxide solution and 16% ammonia water;

[0035] (3) The nickel-cobalt-aluminum salt solution, ammonia water, sodium hydroxide solution, and additive solution were simultaneously introduced into the reactor, and nitrogen was introduced for protection. The pH of the reaction system was set to 11.70±0.10, the ammonia value was 6.0±0.5 g / L, the reaction temperature was 60±1°C, the rotation speed was 500 rpm, the introduction rate of the nickel-cobalt-aluminum salt solution was 1000 mL / h, and the introduction rate of the additive solution was 40 mL / h;

[0036] (4) When the particle size D50 in the reactor grows to 7.0 μm, the feed rate of the additive solution is increased to 80 mL / h, the nitrogen flow is stopped, and 30% hydrogen peroxide is added to make the dissolved oxygen content in the reaction system 25 mg / L. The reaction is continued while other conditions remain unchanged;

[0037] (5) When the particle size D50 in the reactor grows to 9 μm, stop adding nickel-cobalt-aluminum salt solution, increase the reactor temperature to 75 ° C and maintain it, reduce the stirring rate to 350 rpm, remove part of the clear liquid through the concentrator, and replenish the original liquid level of the reactor with pure water, ammonia water, and sodium hydroxide solution to adjust the pH value to 11.4 and the ammonia value to 9 g / L. Continue to introduce the additive solution at a rate of 80 mL / h and maintain the reaction for 8 hours;

[0038] (6) The reaction conditions of the reactor were adjusted to pH 11.70, ammonia value 6.0 g / L, reaction temperature 60° C., rotation speed 500 rpm, introduction rate of nickel-cobalt-aluminum salt solution 1000 mL / h, and introduction rate of additive solution 80 mL / h. The reaction was continued until the particle size D50 grew to 10 μm, and the feeding was stopped to obtain a solution containing the precursor material.

[0039] (7) The solution containing the precursor material obtained in step (6) is aged, centrifugally washed, dried, sieved, and iron removed to obtain a ternary positive electrode material precursor.

[0040] Figure 1 、 Figure 2 The following are the reaction electron micrographs and aging electron micrographs of the ternary cathode material precursor of Example 1 of the present invention, respectively. It can be seen that no cracked or broken balls were found in the full scans of the reaction and aging electron micrographs. The aging electron micrograph is an electron micrograph of the material in the aging tank, and the reaction electron micrograph is an electron micrograph of the material in the reactor.

[0041] Example 2:

[0042] (1) preparing a nickel-cobalt-aluminum salt solution with a total concentration of 115 g / L, wherein the molar ratio of nickel to aluminum is 8:1:1, and preparing an additive solution at 60° C., wherein the additive solution is a mixed aqueous solution containing 0.2% polyvinyl alcohol, 1% polyethylene oxide, and 0.5% gelatin, a sodium hydroxide solution with a mass percentage concentration of 32%, and an ammonia solution with a mass percentage concentration of 16%;

[0043] (2) Add pure water to the reactor until the liquid level reaches 50%, control the temperature at 50°C, introduce nitrogen as a protective gas, and adjust the pH to 11.70 ± 0.05 and the ammonia concentration to 6.0 ± 0.5 g / L using 32% sodium hydroxide solution and 16% ammonia water;

[0044] (3) The nickel-cobalt-aluminum salt solution, ammonia water, sodium hydroxide solution, and additive solution were simultaneously introduced into the reactor, and nitrogen was introduced for protection. The pH of the reaction system was set to 11.70±0.10, the ammonia value was 6.0±0.5 g / L, the reaction temperature was 60±1°C, the rotation speed was 500 rpm, the introduction rate of the nickel-cobalt-aluminum salt solution was 1000 mL / h, and the introduction rate of the additive solution was 40 mL / h;

[0045] (4) When the particle size D50 in the reactor grows to 6.5 μm, the feed rate of the additive solution is increased to 80 mL / h, the nitrogen flow is stopped, and 30% hydrogen peroxide is added to make the dissolved oxygen content in the reaction system 25 mg / L. The reaction is continued while keeping other conditions unchanged;

[0046] (5) When the particle size D50 in the reactor grows to 8.5 μm, stop adding nickel-cobalt-aluminum salt solution, increase the reactor temperature to 75 ° C and maintain it, reduce the stirring rate to 350 rpm, remove part of the clear liquid through the concentrator, and replenish the original liquid level of the reactor with pure water, ammonia water, and sodium hydroxide solution to adjust the pH value to 11.4 and the ammonia value to 9 g / L. Continue to introduce the additive solution at a rate of 80 mL / h and maintain the reaction for 8 hours;

[0047] (6) The reaction conditions of the reactor were adjusted to pH 11.70, ammonia value 6.0 g / L, reaction temperature 60° C., rotation speed 500 rpm, introduction rate of nickel-cobalt-aluminum salt solution 1000 mL / h, and introduction rate of additive solution 80 mL / h. The reaction was continued until the particle size D50 grew to 10 μm, and the feeding was stopped to obtain a solution containing the precursor material.

[0048] (7) The solution containing the precursor material obtained in step (6) is aged, centrifugally washed, dried, sieved, and iron removed to obtain a ternary positive electrode material precursor.

[0049] The precursor was observed by full scanning electron microscopy during reaction and aging, and no ball cracks or broken balls were found.

[0050] Example 3:

[0051] (1) preparing a nickel-cobalt-aluminum salt solution with a total concentration of 115 g / L, wherein the molar ratio of nickel-cobalt-aluminum is 8:1:1, and preparing an additive solution at 60° C., wherein the additive solution is a mixed aqueous solution containing 0.1% polyvinyl alcohol, 1.5% polyethylene oxide, and 0.8% gelatin, a sodium hydroxide solution with a mass percentage concentration of 32%, and an ammonia solution with a mass percentage concentration of 16%;

[0052] (2) Add pure water to the reactor until the liquid level reaches 50%, control the temperature at 60±1°C, introduce nitrogen as a protective gas, and adjust the pH to 11.70±0.05 and the ammonia concentration to 6.0±0.5 g / L using 32% sodium hydroxide solution and 16% ammonia water;

[0053] (3) The nickel-cobalt-aluminum salt solution, ammonia water, sodium hydroxide solution, and additive solution were simultaneously introduced into the reactor, and nitrogen was introduced for protection. The pH of the reaction system was set to 11.70±0.10, the ammonia value was 6.0±0.5 g / L, the reaction temperature was 60±1°C, the rotation speed was 500 rpm, the introduction rate of the nickel-cobalt-aluminum salt solution was 1000 mL / h, and the introduction rate of the additive solution was 40 mL / h;

[0054] (4) When the particle size D50 in the reactor grows to 7.0 μm, the feed rate of the additive solution is increased to 80 mL / h, the nitrogen flow is stopped, and 30% hydrogen peroxide is added to make the dissolved oxygen content in the reaction system 25 mg / L. The reaction is continued while other conditions remain unchanged;

[0055] (5) When the particle size D50 in the reactor grows to 9 μm, stop adding nickel-cobalt-aluminum salt solution, increase the reactor temperature to 75 ° C and maintain it, reduce the stirring rate to 350 rpm, remove part of the clear liquid through the concentrator, and replenish the original liquid level of the reactor with pure water, ammonia water, and sodium hydroxide solution to adjust the pH value to 11.4 and the ammonia value to 9 g / L. Continue to introduce the additive solution at a rate of 80 mL / h and maintain the reaction for 8 hours;

[0056] (6) The reaction conditions of the reactor were adjusted to pH 11.70, ammonia value 6.0 g / L, reaction temperature 60° C., rotation speed 500 rpm, introduction rate of nickel-cobalt-aluminum salt solution 1000 mL / h, and introduction rate of additive solution 80 mL / h. The reaction was continued until the particle size D50 grew to 10 μm, and the feeding was stopped to obtain a solution containing the precursor material.

[0057] (7) The solution containing the precursor material obtained in step (6) is aged, centrifugally washed, dried, sieved, and iron removed to obtain a ternary positive electrode material precursor.

[0058] The precursor was observed by full scanning electron microscopy during reaction and aging, and no ball cracks or broken balls were found.

[0059] Comparative Example 1: (no additive solution added, no segmentation)

[0060] (1) preparing a nickel-cobalt-aluminum salt solution with a total concentration of 115 g / L, wherein the molar ratio of nickel-cobalt-aluminum is 8:1:1, a sodium hydroxide solution with a mass percentage concentration of 32%, and an ammonia solution with a mass percentage concentration of 16%;

[0061] (2) Add pure water to the reactor until the liquid level reaches 50%, control the temperature at 60±1°C, introduce nitrogen as a protective gas, and adjust the pH to 11.70±0.05 and the ammonia concentration to 6.0±0.5 g / L using 32% sodium hydroxide solution and 16% ammonia water;

[0062] (3) The nickel-cobalt-aluminum salt solution, ammonia water, sodium hydroxide solution, and additive solution were simultaneously introduced into the reactor, and nitrogen was introduced for protection. The pH of the reaction system was set to 11.70±0.10, the ammonia value was 6.0±0.5 g / L, the reaction temperature was 60±1°C, the rotation speed was 500 rpm, and the introduction rate of the nickel-cobalt-aluminum salt solution was 1000 mL / h. The reaction was continued until the particle size D50 grew to 10 μm. The feeding was stopped to obtain a solution containing the precursor material.

[0063] (4) The solution containing the precursor material obtained in step (3) is aged, centrifugally washed, dried, sieved, and iron removed to obtain a ternary positive electrode material precursor.

[0064] Figure 3 、 Figure 4 They are respectively the reaction electron microscope image and the aging electron microscope image of the ternary positive electrode material precursor of comparative example 1 of the present invention. The reaction electron microscope 1k point scan shows three broken balls, and the 5k electron microscope has obvious cracks; the aging 1k electron microscope shows 4 broken balls, and the 5k electron microscope has 2 broken balls, and the fine powder is serious.

[0065] Comparative Example 2: (Repairing of ball cracks after co-precipitation)

[0066] (1) preparing a nickel-cobalt-aluminum salt solution with a total concentration of 115 g / L, wherein the molar ratio of nickel-cobalt-aluminum is 8:1:1, a sodium hydroxide solution with a mass percentage concentration of 32%, and an ammonia solution with a mass percentage concentration of 16%;

[0067] (2) Add pure water to the reactor until the liquid level reaches 50%, control the temperature at 60±1°C, introduce nitrogen as a protective gas, and adjust the pH to 11.70±0.05 and the ammonia concentration to 6.0±0.5 g / L using 32% sodium hydroxide solution and 16% ammonia water;

[0068] (3) The nickel-cobalt-aluminum salt solution, ammonia water, and sodium hydroxide solution were simultaneously introduced into the reactor, and nitrogen was introduced for protection. The pH of the reaction system was set to 11.70±0.10, the ammonia value was 6.0±0.5 g / L, the reaction temperature was 60±1°C, the rotation speed was 500 rpm, and the introduction rate of the nickel-cobalt-aluminum salt solution was 1000 mL / h. The reaction was continued until the particle size D50 grew to 10 μm. The feeding was stopped to obtain a solution containing the precursor material.

[0069] (4) The precursor slurry obtained in step (3) is placed in an aging tank, polyvinyl alcohol is introduced to make the concentration of polyvinyl alcohol in the aging tank 0.3%, heated to 75°C, aged for 8 hours, and then centrifuged, washed, dried, sieved, and iron removed to obtain a ternary positive electrode material precursor.

[0070] Figure 5 、 Figure 6 They are respectively the reaction electron microscope images and the aging electron microscope images of the ternary positive electrode material precursor of comparative example 2 of the present invention. It can be seen that the aging electron microscope 1k point scan shows one broken ball and one cracked ball, and the 5k electron microscope has cracks; the aging 1k electron microscope shows one broken ball and one cracked ball, and the 5k electron microscope has cracks, and the ball cracking is improved compared with the reaction.

[0071] Comparative Example 3: (Additive solution has only one component)

[0072] (1) preparing a nickel-cobalt-aluminum salt solution with a total concentration of 115 g / L, wherein the molar ratio of nickel-cobalt-aluminum is 8:1:1, preparing a sodium hydroxide solution with a mass percentage concentration of 32%, an ammonia solution with a mass percentage concentration of 16%, and preparing an additive solution at 60° C., wherein the additive solution is an aqueous solution containing 0.3% polyvinyl alcohol;

[0073] (2) Add pure water to the reactor until the liquid level reaches 50%, control the temperature at 60±1°C, introduce nitrogen as a protective gas, and adjust the pH to 11.70±0.05 and the ammonia concentration to 6.0±0.5 g / L using 32% sodium hydroxide solution and 16% ammonia water;

[0074] (3) The nickel-cobalt-aluminum salt solution, ammonia water, sodium hydroxide solution, and additive solution were simultaneously introduced into the reactor, and nitrogen was introduced for protection. The pH of the reaction system was set to 11.70±0.10, the ammonia value was 6.0±0.5 g / L, the reaction temperature was 60±1°C, the rotation speed was 500 rpm, the introduction rate of the nickel-cobalt-aluminum salt solution was 1000 mL / h, and the introduction rate of the additive solution was 40 mL / h;

[0075] (4) When the particle size D50 in the reactor grows to 7.0 μm, the feed rate of the additive solution is increased to 80 mL / h, the nitrogen flow is stopped, and 30% hydrogen peroxide is added to make the dissolved oxygen content in the reaction system 25 mg / L. The reaction is continued while other conditions remain unchanged;

[0076] (5) When the particle size D50 in the reactor grows to 9 μm, stop adding nickel-cobalt-aluminum salt solution, increase the reactor temperature to 75 ° C and maintain it, reduce the stirring rate to 350 rpm, remove part of the clear liquid through the concentrator, and add a certain amount of pure water, ammonia water, and sodium hydroxide solution to the original liquid level of the reactor. The pH value is adjusted to 11.4 and the ammonia value is adjusted to 9 g / L. Continue to introduce the additive solution at a rate of 80 mL / h and maintain the reaction for 8 hours;

[0077] (6) The reaction conditions of the reactor were adjusted to pH 11.70, ammonia value 6.0 g / L, reaction temperature 60° C., rotation speed 500 rpm, introduction rate of nickel-cobalt-aluminum salt solution 1000 mL / h, and introduction rate of additive solution 80 mL / h. The reaction was continued until the particle size D50 grew to 10 μm, and the feeding was stopped to obtain a solution containing the precursor material.

[0078] (7) The solution containing the precursor material obtained in step (6) is aged, centrifugally washed, dried, sieved, and iron removed to obtain a ternary positive electrode material precursor.

[0079] Figure 7 、 Figure 8They are the reaction electron microscope images and aging electron microscope images of the ternary positive electrode material precursor of comparative example 3 of the present invention. It can be seen that the reaction electron microscope 1k point scan has 3 cracked balls, and the 5k electron microscope has cracks; the aging 1k electron microscope has one broken ball and one cracked ball, and the 5k electron microscope has cracks.

[0080] Comparative Example 4: (No segmentation, other aspects are the same as in Example 1)

[0081] (1) preparing a nickel-cobalt-aluminum salt solution with a total concentration of 115 g / L, wherein the molar ratio of nickel-cobalt-aluminum is 8:1:1, and preparing an additive solution at 60° C., wherein the additive solution is a mixed aqueous solution containing 0.1% polyvinyl alcohol, 1% polyethylene oxide, and 0.1% gelatin, a sodium hydroxide solution with a mass percentage concentration of 32%, and an ammonia solution with a mass percentage concentration of 16%;

[0082] (2) Add pure water to the reactor until the liquid level reaches 50%, control the temperature at 60±1°C, introduce nitrogen as a protective gas, and adjust the pH to 11.70±0.05 and the ammonia concentration to 6.0±0.5 g / L using 32% sodium hydroxide solution and 16% ammonia water;

[0083] (3) The nickel-cobalt-aluminum salt solution, ammonia water, sodium hydroxide solution, and additive solution were simultaneously introduced into the reactor, and nitrogen was introduced for protection. The pH of the reaction system was set to 11.70±0.10, the ammonia value was 6.0±0.5 g / L, the reaction temperature was 60±1°C, the rotation speed was 500 rpm, the introduction rate of the nickel-cobalt-aluminum salt solution was 1000 mL / h, and the introduction rate of the additive solution was 40 mL / h. The reaction was carried out until the particle size D50 grew to 10 μm, and the feeding was stopped to obtain a solution containing the precursor material;

[0084] (4) The solution containing the precursor material obtained in step (3) is aged, centrifugally washed, dried, sieved, and iron removed to obtain a ternary positive electrode material precursor.

[0085] The reaction electron microscope images and aging electron microscope images of the ternary positive electrode material precursor obtained in comparative example 4 show that 2 cracked balls are found in the 1k point scan and there is a crack in the 5k electron microscope; there is 1 broken ball and 1 cracked ball in the aging 1k electron microscope and there is a crack in the 5k electron microscope.

[0086] Comparative Example 5: (No oxidant was added, other conditions were the same as in Example 1)

[0087] (1) preparing a nickel-cobalt-aluminum salt solution with a total concentration of 115 g / L, wherein the molar ratio of nickel-cobalt-aluminum is 8:1:1, and preparing an additive solution at 60° C., wherein the additive solution is a mixed aqueous solution containing 0.1% polyvinyl alcohol, 1% polyethylene oxide, and 0.1% gelatin, a sodium hydroxide solution with a mass percentage concentration of 32%, and an ammonia solution with a mass percentage concentration of 16%;

[0088] (2) Add pure water to the reactor until the liquid level reaches 50%, control the temperature at 60±1°C, introduce nitrogen as a protective gas, and adjust the pH to 11.70±0.05 and the ammonia concentration to 6.0±0.5 g / L using 32% sodium hydroxide solution and 16% ammonia water;

[0089] (3) The nickel-cobalt-aluminum salt solution, ammonia water, sodium hydroxide solution, and additive solution were simultaneously introduced into the reactor, and nitrogen was introduced for protection. The pH of the reaction system was set to 11.70±0.10, the ammonia value was 6.0±0.5 g / L, the reaction temperature was 60±1°C, the rotation speed was 500 rpm, the introduction rate of the nickel-cobalt-aluminum salt solution was 1000 mL / h, and the introduction rate of the additive solution was 40 mL / h;

[0090] (4) When the particle size D50 in the reactor grows to 7.0 μm, the feed rate of the additive solution is increased to 80 mL / h, and the reaction is continued while keeping other conditions unchanged;

[0091] (5) When the particle size D50 in the reactor grows to 9 μm, stop adding nickel-cobalt-aluminum salt solution, increase the reactor temperature to 75 ° C and maintain it, reduce the stirring rate to 350 rpm, remove part of the clear liquid through the concentrator, and add a certain amount of pure water, ammonia water, and sodium hydroxide solution to the original liquid level of the reactor. The pH value is adjusted to 11.4 and the ammonia value is adjusted to 9 g / L. Continue to introduce the additive solution at a rate of 80 mL / h and maintain the reaction for 8 hours;

[0092] (6) The reaction conditions of the reactor were adjusted to pH 11.70, ammonia value 6.0 g / L, reaction temperature 60° C., rotation speed 500 rpm, introduction rate of nickel-cobalt-aluminum salt solution 1000 mL / h, and introduction rate of additive solution 80 mL / h. The reaction was continued until the particle size D50 grew to 10 μm, and the feeding was stopped to obtain a solution containing the precursor material.

[0093] (7) The solution containing the precursor material obtained in step (6) is aged, centrifugally washed, dried, sieved, and iron removed to obtain a ternary positive electrode material precursor.

[0094] The reaction electron microscope image and aging electron microscope image of the ternary positive electrode material precursor obtained in comparative example 5 were observed. It can be seen that there is a crack in the 1k point scan and there is a crack in the 5k electron microscope; there is one cracked ball in the 1k electron microscope and there is a crack in the 5k electron microscope after aging.

[0095] Comparative Example 6: (No curing step, other steps are the same as in Example 1)

[0096] (1) preparing a nickel-cobalt-aluminum salt solution with a total concentration of 115 g / L, wherein the molar ratio of nickel-cobalt-aluminum is 8:1:1, and preparing an additive solution at 60° C., wherein the additive solution is a mixed aqueous solution containing 0.1% polyvinyl alcohol, 1% polyethylene oxide, and 0.1% gelatin, a sodium hydroxide solution with a mass percentage concentration of 32%, and an ammonia solution with a mass percentage concentration of 16%;

[0097] (2) Add pure water to the reactor until the liquid level reaches 50%, control the temperature at 60±1°C, introduce nitrogen as a protective gas, and adjust the pH to 11.70±0.05 and the ammonia concentration to 6.0±0.5 g / L using 32% sodium hydroxide solution and 16% ammonia water;

[0098] (3) The nickel-cobalt-aluminum salt solution, ammonia water, sodium hydroxide solution, and additive solution were simultaneously introduced into the reactor, and nitrogen was introduced for protection. The pH of the reaction system was set to 11.70±0.10, the ammonia value was 6.0±0.5 g / L, the reaction temperature was 60±1°C, the rotation speed was 500 rpm, the introduction rate of the nickel-cobalt-aluminum salt solution was 1000 mL / h, and the introduction rate of the additive solution was 40 mL / h;

[0099] (4) When the particle size D50 in the reactor grows to 7.0 μm, the feed rate of the additive solution is increased to 80 mL / h, the nitrogen flow is stopped, and 30% hydrogen peroxide is added to make the dissolved oxygen content in the reaction system 25 mg / L. The reaction is continued while other conditions remain unchanged;

[0100] (5) When the particle size D50 in the reactor grows to 9 μm, the reaction conditions of the reactor are adjusted to pH 11.70, ammonia value 6.0 g / L, reaction temperature 60°C, rotation speed 500 rpm, the introduction rate of nickel cobalt aluminum salt solution is 1000 mL / h, and the introduction rate of additive solution is 80 mL / h. The reaction is continued until the particle size D50 grows to 10 μm, and the feeding is stopped to obtain a solution containing the precursor material;

[0101] (6) The solution containing the precursor material obtained in step (5) is aged, centrifugally washed, dried, sieved, and iron removed to obtain a ternary positive electrode material precursor.

[0102] The reaction electron microscope images and aging electron microscope images of the ternary positive electrode material precursor obtained in comparative example 6 show that there are 2 cracked balls in the 1k point scan and one broken ball pattern in the 5k electron microscope; there is one cracked ball in the 1k electron microscope and one broken ball pattern in the 5k electron microscope after aging.

[0103] Comparative Example 7: (Additive solution flow rate was not increased, other conditions were the same as in Example 1)

[0104] (1) preparing a nickel-cobalt-aluminum salt solution with a total concentration of 115 g / L, wherein the molar ratio of nickel-cobalt-aluminum is 8:1:1, and preparing an additive solution at 60° C., wherein the additive solution is a mixed aqueous solution containing 0.1% polyvinyl alcohol, 1% polyethylene oxide, and 0.1% gelatin, a sodium hydroxide solution with a mass percentage concentration of 32%, and an ammonia solution with a mass percentage concentration of 16%;

[0105] (2) Add pure water to the reactor until the liquid level reaches 50%, control the temperature at 60±1°C, introduce nitrogen as a protective gas, and adjust the pH to 11.70±0.05 and the ammonia concentration to 6.0±0.5 g / L using 32% sodium hydroxide solution and 16% ammonia water;

[0106] (3) The nickel-cobalt-aluminum salt solution, ammonia water, sodium hydroxide solution, and additive solution were simultaneously introduced into the reactor, and nitrogen was introduced for protection. The pH of the reaction system was set to 11.70±0.10, the ammonia value was 6.0±0.5 g / L, the reaction temperature was 60±1°C, the rotation speed was 500 rpm, the introduction rate of the nickel-cobalt-aluminum salt solution was 1000 mL / h, and the introduction rate of the additive solution was 40 mL / h;

[0107] (4) When the particle size D50 in the reactor grows to 7.0 μm, stop the nitrogen flow and add 30% hydrogen peroxide to make the dissolved oxygen content in the reaction system 25 mg / L. Continue the reaction while keeping other conditions unchanged.

[0108] (5) When the particle size D50 in the reactor grows to 9 μm, stop adding nickel-cobalt-aluminum salt solution, increase the reactor temperature to 75 ° C and maintain it, reduce the stirring rate to 350 rpm, remove part of the clear liquid through the concentrator, and replenish the original liquid level of the reactor with pure water, ammonia water, and sodium hydroxide solution to adjust the pH value to 11.4 and the ammonia value to 9 g / L. Continue to introduce the additive solution at a rate of 40 mL / h and maintain the reaction for 8 hours;

[0109] (6) The reaction conditions of the reactor were adjusted to pH 11.70, ammonia value 6.0 g / L, reaction temperature 60° C., rotation speed 500 rpm, introduction rate of nickel-cobalt-aluminum salt solution 1000 mL / h, and introduction rate of additive solution 80 mL / h. The reaction was continued until the particle size D50 grew to 10 μm, and the feeding was stopped to obtain a solution containing the precursor material.

[0110] (7) The solution containing the precursor material obtained in step (6) is aged, centrifugally washed, dried, sieved, and iron removed to obtain a ternary positive electrode material precursor.

[0111] The reaction electron microscope image and aging electron microscope image of the ternary positive electrode material precursor obtained in comparative example 7 were observed. It can be seen that there is one cracked ball in the 1k point scan and there is no abnormality in the 5k electron microscope; there is one cracked ball in the 1k electron microscope and one crack in the 5k electron microscope after aging.

Claims

1. A method for preparing a ternary cathode material precursor, characterized in that: The following steps are involved: (1) preparing a metal salt solution, a complexing agent solution, a precipitant solution and an additive solution, wherein the metal salt solution is an aqueous solution containing nickel salt, cobalt salt, manganese salt or aluminum salt, and the additive solution is an aqueous solution of at least one of polyethylene glycol, polyvinyl alcohol and polyacrylamide and gelatin; (2) Add water, complexing agent solution, and precipitant solution into the reactor, stir, and maintain constant temperature to prepare the reactor bottom solution; (3) Adding metal salt solution, additive solution, precipitant solution, and complexing agent solution into a constant temperature reactor to carry out a coprecipitation reaction, and continuously passing an inert protective gas into the reactor during the reaction; (4) When the particle size D50 in the reactor grows to 65% to 75% of the target particle size, the feed rate of the additive solution is increased by 20% to 50% compared with the feed rate in step (3), the inert protective gas is stopped, and the oxidant is introduced to continue the reaction; (5) When the particle size D50 in the reactor grows to 85% to 95% of the target particle size, stop feeding the metal salt solution and the oxidant, continue to feed the additive solution, increase the reactor temperature by 20% to 50% compared with the reactor temperature in step (3), reduce the stirring rate by 20% to 30% compared with that in step (3), increase the ammonia value by 1 to 4 g / L compared with that in step (3), and reduce the pH value by 0.1 to 0.3 compared with that in step (3), and maintain the reaction for 6 to 8 hours; (6) The temperature, pH value, stirring rate, ammonia value, and feeding rate of the reaction kettle are then restored to the reaction conditions of step (3) and the reaction is continued until the particle size D50 grows to the target particle size, and the feeding is stopped to obtain a solution containing the precursor material; (7) The solution containing the precursor material obtained in step (6) is aged, washed, dried, sieved, and iron removed to obtain a ternary positive electrode material precursor.

2. The method for preparing a ternary cathode material precursor according to claim 1, wherein: The oxidant is hydrogen peroxide with a mass concentration of 20% to 40%. The oxidant is introduced to control the dissolved oxygen content of the solution in the reaction kettle to be 15 to 30 mg / L.

3. The method for preparing a ternary cathode material precursor according to claim 1, wherein: The total concentration of metal ions in the metal salt solution is 1 to 3 mol / L. The metal salt solution is an aqueous solution containing nickel salt, cobalt salt and manganese salt. The molar percentage of nickel ions in the metal salt solution is 60% to 100% of the total metal ions, the molar percentage of cobalt ions in the total metal ions is 0% to 40%, and the molar percentage of manganese in the total metal ions is 0% to 40%.

4. The method for preparing a ternary cathode material precursor according to claim 1, wherein: The metal salt solution includes a nickel-cobalt salt solution and an aluminum salt solution. The total concentration of metal ions in the nickel-cobalt salt solution is 1 to 2.5 mol / L, wherein the molar ratio of nickel salt to cobalt salt in the nickel-cobalt salt solution is 0.6 to 1:0 to 0.4, the concentration of aluminum in the aluminum salt solution is 0.05 to 0.3 mol / L, the introduction rate of the nickel-cobalt salt solution is 2 to 10 L / h, and the introduction rate of the aluminum salt solution is 0.5 to 4 L / h.

5. The method for preparing a ternary cathode material precursor according to claim 1, wherein: In step (3), the pH value of the reaction system is controlled to be 10.0-12.5, the ammonia value is 2-20 g / L, the temperature is 40-80° C., the stirring rate is 100-1000 rpm, and the introduction rate of the metal salt solution is 1-15 L / h.

6. The method for preparing a ternary cathode material precursor according to claim 1, wherein: The additive solution is an aqueous solution of at least one of polyethylene glycol, polyvinyl alcohol, and polyacrylamide and gelatin, wherein the total mass concentration of polyethylene glycol, polyvinyl alcohol, and polyacrylamide in the additive solution is 0-2.0%, and the mass concentration of gelatin is 0.1-1.0%; the feed rate of the additive solution is 0-1.0 L / h.

7. The method for preparing a ternary cathode material precursor according to claim 1, wherein: The inert protective gas is nitrogen.

8. The method for preparing a ternary cathode material precursor according to claim 1, wherein: The precipitant solution is a sodium hydroxide solution with a mass concentration of 28% to 34%, and the complexing agent solution is an ammonia solution with a mass concentration of 16% to 25%.

9. The method for preparing a ternary cathode material precursor according to claim 1, wherein: The target particle size of the precursor material particles is 6 to 11 μm.

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