A method for preparing a high-nickel lithium nickel cobalt manganese oxide cathode material

Abstract

A method for preparing high-nickel lithium nickel cobalt manganese oxide (LiNi1) cathode material belongs to the field of lithium-ion battery cathode material preparation technology. The main steps include: preparing nickel cobalt manganese hydrotalcite nanosheets and spherical nickel hydroxide particles respectively; coating the nickel hydroxide surface with nickel cobalt manganese hydrotalcite using solid-phase ball milling; uniformly mixing the nickel hydroxide coated with nickel cobalt manganese hydrotalcite with a lithium compound and calcining at high temperature to obtain lithium nickel cobalt manganese oxide (LiNi1). x y Co x Mn y O2 cathode material. The advantages of this invention are that it avoids the need for inert gas protection during co-precipitation, utilizes the synergistic diffusion effect to achieve a uniform distribution of nickel, cobalt, and manganese in the cathode material, and leverages the buffer layer effect of nickel-cobalt-manganese lithium oxide to slow down the lithium-ion diffusion rate, allowing Ni... 2+ Fully oxidized to Ni 3+ This method reduces Li / Ni mixing; it is simple, highly controllable, and produces products with good batch stability.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery cathode material preparation technology, and specifically relates to a method for preparing high-nickel lithium nickel cobalt manganese oxide cathode material, namely, using spherical nickel hydroxide coated with nickel cobalt manganese hydrotalcite nanosheets as a precursor, and synthesizing high-nickel lithium nickel cobalt manganese oxide cathode material by lithiation calcination. Background Technology

[0002] Lithium-ion batteries have developed rapidly in recent years, and the widespread use of new energy vehicles has broadened their application scope. Therefore, the demand for high-capacity and long-cycle-life lithium-ion batteries is becoming increasingly urgent. In the global process of moving towards decarbonization and electrification, lithium-ion batteries have become an undisputed "energy star," and cathode materials, as a key component of lithium-ion batteries, play a crucial role. Ternary materials, through high-nickel content, are continuously breaking through energy density ceilings and offer lower costs, meeting the needs of long-range electric vehicles. Currently, they are continuously unlocking new heights in energy efficiency for high-nickel lithium-ion batteries, empowering future energy transformation.

[0003] In the preparation of high-nickel lithium nickel cobalt manganese oxide, the precursor plays a crucial role in the overall performance of the battery cathode material. Currently, lithium nickel cobalt manganese oxide (LiNi1)... x y Co x Mn y O2 is mainly prepared by co-precipitation. This process involves mixing a salt solution of nickel, cobalt, and manganese (such as sulfates and nitrates) with a precipitant (such as NaOH) and a complexing agent (such as NH4OH). By controlling parameters such as pH, temperature, and stirring speed, a nickel-cobalt-manganese hydroxide precursor with uniform elemental distribution is generated. In Chinese Invention Patent Publication No. CN116873989A (1), Shi Haiyong et al. first synthesized a nickel-cobalt-manganese ternary precursor by co-precipitation. By controlling the pH and oxygen volume content during the co-precipitation process, a nickel-cobalt-manganese ternary cathode material precursor with high specific surface area was obtained. Then, it was calcined with lithium source materials such as LiOH to obtain lithium nickel-cobalt-manganese oxide material. In Chinese Invention Patent Publication No. CN120774480A (2), Wang Qinghua et al. also used co-precipitation to prepare a rate-capable high-nickel ternary material, which solved the problem of the contradiction between the rate performance and structural stability of high-nickel materials. However, since the oxygen content needs to be strictly controlled in the above two reaction processes, nitrogen or argon gas needs to be introduced for protection, which increases the production cost to some extent. Furthermore, the reaction parameters need to be strictly controlled to ensure product consistency. Therefore, batch stability of products has become a difficult problem in large-scale production.

[0004] Therefore, there is an urgent need for a method that can improve product consistency and save costs to synthesize high-nickel lithium nickel cobalt manganese oxide cathode materials. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing high-nickel lithium nickel cobalt manganese oxide cathode material using nickel cobalt manganese hydrotalcite nanosheets coated with spherical nickel hydroxide as a precursor. The method involves first preparing spherical nickel hydroxide particles and nickel cobalt manganese hydrotalcite nanosheets separately. Then, the nickel cobalt manganese hydrotalcite nanosheets are coated onto the surface of the spherical nickel hydroxide particles using a solid-state ball milling method. The nickel hydroxide coated with nickel cobalt manganese hydrotalcite is then uniformly mixed with a lithium compound and calcined at high temperature to obtain the high-nickel lithium nickel cobalt manganese oxide cathode material. The chemical composition of the high-nickel lithium nickel cobalt manganese oxide is LiNi1. x y Co x Mn y O2 cathode material, wherein 0.8 ≤ 1 - xy ≤ 0.9, 0 < x ≤ 0.15, 0 < y ≤ 0.10. The process flow of this preparation method is as follows. Figure 1 As shown, the specific process steps are as follows: (1) Preparation of spherical nickel hydroxide particles: Prepare nickel salt solutions with a concentration of 2-4 mol / L, ammonia solutions with a concentration of 2-4 mol / L, and sodium hydroxide solutions with a concentration of 5-7 mol / L. Dilute 25%-28% ammonia water to 4-7 g / L and add it to the reactor. At the same time, add 5-7 mol / L sodium hydroxide solution as the base solution, ensuring that the pH of the base solution is within the range of 11.20-11.60. Set the stirring speed of the reactor to 600-750 rpm and maintain the reactor temperature at 50-60°C. o The reaction process is maintained constant throughout. Nickel salt, sodium hydroxide, and ammonia are simultaneously injected into the bottom solution. At the start of the reaction, the flow rate of the sodium hydroxide solution is adjusted to maintain the pH of the reaction solution at 11.20-11.60, at which point a suspension is formed, in which the solid particles of Ni(OH)2 have a particle size D50 of 1-2 μm. After 6 hours of reaction, the flow rate of sodium hydroxide is reduced to lower the pH in the reactor by 0.2-0.4. When the particles grow to 10 μm, the feeding is stopped, and the Ni(OH)2 suspension in the reactor is collected. The suspension is repeatedly washed and filtered until the pH of the filtrate is neutral. The washed filter cake is then heated to 80-100 °C. o Drying at C for 12-16 hours yields uniform spherical nickel hydroxide with a D50 of 10-14 μm. The nickel salt is one or more of nickel sulfate, nickel chloride, nickel acetate, or nickel nitrate.

[0006] (2) Preparation of nickel-cobalt-manganese hydrotalcite nanosheets: Nickel, cobalt, and manganese salts were weighed according to a molar ratio of 1-3:1-2:1 and dissolved in deionized water to prepare a salt solution A with a total metal ion concentration of 0.2-0.5 mol / L. NaOH and Na₂CO₃ were dissolved in deionized water to prepare an alkaline solution B with a NaOH concentration of 0.3-0.4 mol / L and a Na₂CO₃ concentration of 0.1-0.2 mol / L. Equal volumes of salt solution A and alkaline solution B were simultaneously poured into a colloid mill at a speed of 3000-4000 rpm for mixing. The resulting suspension was then subjected to a sterilization process at 80-100°C. o Aging in a C water bath for 3-4 hours, followed by washing with deionized water, and then rinsing the washed filter cake at 80-120°C. o Drying at C for 10-12 h yields nickel-cobalt-manganese hydrotalcite nanosheets. The nickel salt is one or more of nickel sulfate, nickel chloride, nickel acetate, or nickel nitrate; the cobalt salt is one or more of cobalt sulfate, cobalt chloride, cobalt acetate, or cobalt nitrate; and the manganese salt is one or more of manganese sulfate, manganese chloride, manganese acetate, or manganese nitrate.

[0007] (3) Preparation of finished materials: according to the lithium nickel cobalt manganese oxide LiNi1 x y Co x Mn y In the O2 cathode material, the spherical nickel hydroxide prepared in step (1) and the nickel-cobalt-manganese hydrotalcite nanosheets from step (2) were weighed according to the molar ratio of Ni, Co, and Mn. The two were then mixed using a solid-phase ball mill at 200-400 rpm for 2-4 hours to obtain a spherical nickel hydroxide precursor coated with nickel-cobalt-manganese hydrotalcite. The hydrotalcite-coated nickel hydroxide precursor and the lithium source were weighed according to a molar ratio of metal ions in the nickel-cobalt-manganese hydrotalcite nanosheet-coated spherical nickel hydroxide precursor to lithium ions in the lithium compound of 1:1.01-1.05, and mixed using a solid-phase ball mill for 1-3 hours. The mixed sample was then in an oxygen atmosphere at 5-10... o Heating rate increased to 400-550 °C / min o C, and sinter at that temperature for 7-10 h, followed by 5-10 h. o Heating rate increased to 740-780 °C / min o The cathode material is prepared by sintering at a constant temperature for 10-18 hours (C) and then naturally cooled to room temperature. The lithium compound is one or more of lithium hydroxide, lithium carbonate, or lithium nitrate.

[0008] The morphology of the samples was characterized using a Zeiss Supra 55 field emission scanning electron microscope (SEM). Figure 2 The image shows a scanning electron microscope (SEM) image of nickel-cobalt-manganese hydrotalcite nanosheets. The radial dimensions of the nickel-cobalt-manganese hydrotalcite nanosheets are 60-100 nm, and the thickness is 10-20 nm. The particle size is small and the distribution is relatively uniform. The nanoscale modified material is conducive to uniform mixing with the precursor and lithium compound during ball milling, and it is easier to form a material with uniform elemental distribution after calcination. Figure 3 The image shows a scanning electron microscope (SEM) image of nickel hydroxide, revealing that the particles are regularly spherical with a size of 10-12 μm. Figure 4 Scanning electron microscope image of nickel-cobalt-manganese hydrotalcite-coated nickel hydroxide precursor. Figure 5 LiNi obtained by lithiation and calcination of nickel hydroxide precursor coated with nickel cobalt manganese hydrotalcite 0.90 Co 0.05 Mn 0.05 Scanning electron microscopy image of the O2 sample; the size of the coated and calcined sample did not change significantly compared to the spherical nickel hydroxide. Figure 6 LiNi obtained by lithiation and calcination of nickel hydroxide precursor coated with nickel cobalt manganese hydrotalcite 0.90 Co 0.05 Mn 0.05 The XRD pattern of the O2 sample corresponds one-to-one with the diffraction peaks of the standard spectrum of lithium nickel oxide (LiNiO2) PDF#09-0063, and no impurity phase is present, indicating that a high-purity lithium nickel cobalt manganese oxide product has been synthesized.

[0009] The finished material prepared by the methods in the embodiments and comparative examples of the present invention is used as the positive electrode active material. It is mixed with acetylene black conductive agent and polyvinylidene fluoride binder at a mass ratio of 8:1:1, and coated onto the surface of an aluminum foil current collector. 110 o After drying at C, the product is rolled and pressed at 120°C. o Vacuum drying was performed in a C vacuum oven for 12 h. Electrode sheets with a diameter of 1 cm were obtained using a die-casting machine as the positive electrode, lithium metal sheets as the negative electrode, polyethylene film as the separator, and 1 mol / L LiPF6+EC+DMC as the electrolyte. Button cells were assembled in a M. Braun UniLab glove box (H2O < 1 ppm, O2 < 1 ppm). Electrochemical performance was tested using a Wuhan Landian CT2001A battery tester, with a voltage range of 2.75-4.3 V (vs. Li). + LiNi(Ni) cobalt manganese oxide, 1 C = 274 mA / g. The test results are shown in Table 1. The lithium nickel cobalt manganese oxide (LiNi) prepared by the method of this embodiment of the invention... 0.90 Co 0.05 Mn 0.05 O2 and LiNi 0.80 Co 0.10 Mn 0.10LiNi prepared by the O2 sample comparison method 0.90 Co 0.05 Mn 0.05 O2 and LiNi 0.80 Co 0.10 Mn 0.10 O2 has a higher specific capacity and significantly improved cycle performance.

[0010] Table 1. List of electrochemical data for lithium nickel cobalt manganese oxide electrode materials prepared in the embodiments and comparative examples of the present invention. In summary, this invention develops a novel method for preparing high-nickel lithium nickel cobalt manganese oxide cathode materials using spherical nickel hydroxide coated with nickel cobalt manganese hydrotalcite as a precursor. Compared with the method for preparing lithium nickel cobalt manganese oxide using nickel cobalt manganese hydroxide as a precursor, it has the following significant advantages: (1) Since manganese is easily oxidized in a strongly alkaline environment, the traditional co-precipitation method for preparing nickel cobalt manganese hydroxide precursor requires inert gas protection. However, the method of this invention can synthesize spherical nickel hydroxide and nickel cobalt manganese hydrotalcite nanosheets separately in an air atmosphere, thereby avoiding the use of inert gas protection during the co-precipitation process, saving gas supply equipment and operating costs, and making the production process simpler and more controllable, thus improving the batch stability of the product. (2) Based on the characteristic that Ni and Co easily diffuse into each other to form a solid solution, the synergistic diffusion effect is used to achieve the uniform distribution of nickel, cobalt, and manganese in the cathode material, avoiding the process of preparing nickel cobalt manganese hydroxide precursor. (3) The nickel cobalt manganese lithium oxide buffer layer effect formed during the lithiation roasting process slows down the lithium ion diffusion rate, making Ni 2+ Fully oxidized to Ni 3+ (4) By adjusting the composition and amount of hydrotalcite, high-nickel lithium nickel cobalt manganese oxide cathode materials with different chemical compositions can be synthesized, and the process has a wide range of applications. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the process flow for synthesizing high-nickel lithium nickel cobalt manganese oxide cathode material using nickel cobalt manganese hydrotalcite nanosheets coated with spherical nickel hydroxide particles as a precursor.

[0012] Figure 2 This is a scanning electron microscope image of the nickel-cobalt-manganese hydrotalcite nanosheets synthesized in Example 1 of this invention.

[0013] Figure 3 This is a scanning electron microscope image of nickel hydroxide synthesized in Example 1 of this invention.

[0014] Figure 4 This is a scanning electron microscope image of the nickel-cobalt-manganese hydrotalcite nanosheet-coated spherical nickel hydroxide precursor of Example 1 of the present invention.

[0015] Figure 5 The LiNi obtained in Example 1 of this invention 0.90 Co 0.05 Mn 0.05 Scanning electron microscope image of O2.

[0016] Figure 6 The LiNi obtained in Example 1 of this invention 0.90 Co 0.05 Mn 0.05 X-ray diffraction pattern of O2. The horizontal axis represents the diffraction angle 2θ, in degrees (°). o The vertical axis represents the diffraction peak intensity, in absolute units (au); PDF#09-0063 is the standard spectrum of lithium nickelate (LiNiO2).

[0017] Figure 7 This is the LiNi prepared in Example 1 of the present invention. 0.90 Co 0.05 Mn 0.05 The first-week charge-discharge curves of O2 at room temperature are shown. The horizontal axis represents the discharge specific capacity in milliampere-hours per gram (mAh / g); the vertical axis represents the voltage in volts relative to lithium metal (V vs. Li). + / Li). Detailed Implementation

[0018] To further illustrate the technical solution of the present invention, the embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the technical solution of the present invention, and not for limiting the claims of the present invention.

[0019] Example 1 (1) Preparation of spherical nickel hydroxide: A 2 mol / L nickel salt solution, a 2 mol / L ammonia solution, and a 6 mol / L sodium hydroxide solution were prepared. Ammonia solution with a mass concentration of 25%-28% was diluted to 5 g / L, and 30 L of the corresponding concentration of ammonia solution was added to the reactor. Simultaneously, a 6 mol / L sodium hydroxide solution was added as a base solution, ensuring the pH of the base solution was 11.30. The stirring speed of the reactor was set to 750 rpm, and the stirring speed was reduced by 50 rpm for every 1 μm of particle growth after the particles reached 5 μm. The reactor temperature was maintained at 55°C. oThe reaction process was kept constant throughout. Nickel salt, sodium hydroxide, and ammonia were simultaneously injected into the bottom solution, maintaining the flow rates of nickel salt at 1.2 L / h, sodium hydroxide at 0.8 L / h, and ammonia at 0.33 L / h. At the start of the reaction, the flow rate of the sodium hydroxide solution was adjusted to achieve a pH of 11.50, resulting in a suspension with Ni(OH)₂ solid particles having a D50 of 1-2 μm. After 6 hours of reaction, the flow rate of sodium hydroxide was reduced to lower the pH in the reactor by 0.2-0.4. Feeding was stopped when the particles grew to 10 μm, and the Ni(OH)₂ suspension was collected. The suspension was repeatedly washed and filtered until the filtrate pH was neutral. The washed filter cake was then filtered at 100°C. o After drying at C for 12 h, spherical nickel hydroxide with a D50 of 10 μm was obtained.

[0020] (2) Preparation of nickel-cobalt-manganese hydrotalcite nanosheets: Nickel, cobalt, and manganese salts were weighed according to a molar ratio of x:y:z = 1:1:1, and dissolved in deionized water to prepare salt solution A with metal ion concentrations of 0.1 mol / L. NaOH and Na₂CO₃ were dissolved in deionized water to prepare alkaline solution B with NaOH concentration of 0.48 mol / L and Na₂CO₃ concentration of 0.2 mol / L. 200 mL of equal volumes of salt solution A and alkaline solution B were simultaneously poured into a colloid mill at 3000 rpm for mixing. The resulting suspension was then heated at 95°C. o Aging was carried out in a C water bath for 2 hours. After aging, the filter cake was washed with deionized water until the pH of the supernatant was 7. The washed filter cake was then heated in an 80°C water bath. o Nickel-cobalt-manganese hydrotalcite nanosheets were obtained by drying at C for 12 h.

[0021] (3) Preparation of finished materials: according to the lithium nickel cobalt manganese oxide (LiNi) 0.90 Co 0.05 Mn 0.05 In the O2 cathode material, the spherical nickel hydroxide prepared in step (1) and the nickel-cobalt-manganese hydrotalcite nanosheets prepared in step (2) were weighed according to the molar ratio of Ni, Co, and Mn. They were then mixed using a solid-phase ball mill at 200 rpm for 3 hours to obtain a spherical nickel hydroxide precursor coated with nickel-cobalt-manganese hydrotalcite. The hydrotalcite-coated nickel hydroxide precursor and lithium hydroxide were weighed according to a molar ratio of metal ions in the nickel-cobalt-manganese hydrotalcite nanosheet-coated spherical nickel hydroxide precursor to lithium ions in lithium hydroxide of 1:1.05, and mixed using a solid-phase ball mill at 200 rpm for 2 hours. The mixed sample was then subjected to a 3% oxygen atmosphere. o Heating rate increased to 500 °C / min oC, and sintered at that temperature for 5 h, followed by 3 o Heating rate increased to 740 °C / min o C, and calcined at a constant temperature for 12 h, finally cooled naturally to room temperature to obtain lithium nickel cobalt manganese oxide (LiNi). 0.90 Co 0.05 Mn 0.05 O2 cathode material.

[0022] The lithium nickel cobalt manganese oxide (LiNi) prepared in this embodiment 0.90 Co 0.05 Mn 0.05 Electrochemical performance tests were conducted on O2 sample-assembled coin cells at room temperature, and the results are shown in Table 1. Figure 7 As shown.

[0023] Example 2 (1) Preparation of spherical nickel hydroxide: A nickel salt solution with a concentration of 2 mol / L, an ammonia solution with a concentration of 2 mol / L, and a sodium hydroxide solution with a concentration of 6 mol / L were prepared. Ammonia solution with a mass concentration of 25%-28% was diluted to 6 g / L, and 30 L of the corresponding concentration of ammonia solution was added to the reactor. Simultaneously, a sodium hydroxide solution with a concentration of 7 mol / L was added as a base solution, ensuring the pH of the base solution was 11.40. The stirring speed of the reactor was set to 750 rpm, and after the particles grew to 5 μm, the stirring speed was reduced by 100 rpm for every 1 μm of growth. The reactor temperature was maintained at 55°C. o The reaction process was kept constant throughout. Nickel salt, sodium hydroxide, and ammonia were simultaneously injected into the bottom solution, maintaining the flow rates of nickel salt at 1.2 L / h, sodium hydroxide at 0.8 L / h, and ammonia at 0.33 L / h. At the start of the reaction, the flow rate of the sodium hydroxide solution was adjusted to achieve a pH of 11.40, at which point a suspension was formed with Ni(OH)₂ solid particles having a D50 of 1-2 μm. After 6 h of reaction, the flow rate of sodium hydroxide was reduced to lower the pH in the reactor by 0.2-0.4. Feeding was stopped when the particles grew to 10 μm, and the Ni(OH)₂ suspension was collected. The suspension was repeatedly washed and filtered until the filtrate pH was neutral. The washed filter cake was then filtered at 100°C. o After drying at C for 12 h, spherical nickel hydroxide with a D50 of 10 μm was obtained.

[0024] (2) Preparation of nickel-cobalt-manganese hydrotalcite nanosheets: Nickel, cobalt, and manganese salts were weighed according to a molar ratio of x:y:z = 2:1:1, and dissolved in deionized water to prepare salt solutions A with metal ion concentrations of 0.2 mol / L, 0.1 mol / L, and 0.1 mol / L, respectively. NaOH and Na₂CO₃ were dissolved in deionized water to prepare alkaline solutions B with NaOH concentration of 0.64 mol / L and Na₂CO₃ concentration of 0.2 mol / L. Equal volumes of salt solution A and alkaline solution B were simultaneously poured into a colloid mill at 3000 rpm for mixing. The resulting suspension was then heated at 95°C. o Aging was carried out in a C water bath for 3 hours. After aging, the filter cake was washed with deionized water until the pH of the supernatant was 7. The washed filter cake was then heated in an 80°C water bath. o Nickel-cobalt-manganese hydrotalcite nanosheets were obtained by drying at C for 12 hours.

[0025] (3) Preparation of finished materials: according to the lithium nickel cobalt manganese oxide (LiNi) 0.90 Co 0.05 Mn 0.05 In the O2 cathode material, the spherical nickel hydroxide prepared in step (1) and the nickel-cobalt-manganese hydrotalcite nanosheets prepared in step (2) were weighed according to the molar ratio of Ni, Co, and Mn. They were then mixed using a solid-phase ball mill at 400 rpm for 1 h to obtain a spherical nickel hydroxide precursor coated with nickel-cobalt-manganese hydrotalcite. The hydrotalcite-coated nickel hydroxide precursor and lithium hydroxide were weighed according to a molar ratio of metal ions in the nickel-cobalt-manganese hydrotalcite nanosheet-coated spherical nickel hydroxide precursor to lithium ions in lithium hydroxide of 1:1.01, and mixed using a solid-phase ball mill at 200 rpm for 2 h. The mixed sample was then in an oxygen atmosphere at 5... o Heating rate increased to 470 °C / min o C, and sintered at that temperature for 7 h, followed by 5 o Heating rate increased to 770 °C / min o C, and sintered at a constant temperature for 10 h, and finally naturally cooled to room temperature to obtain lithium nickel cobalt manganese oxide cathode material.

[0026] The lithium nickel cobalt manganese oxide (LiNi) prepared in this embodiment 0.90 Co 0.05 Mn 0.05 The electrochemical performance of O2 sample assembled coin cells was tested at room temperature, and the results are shown in Table 1.

[0027] Example 3 (1) Preparation of spherical nickel hydroxide: A nickel salt solution with a concentration of 2 mol / L, an ammonia solution with a concentration of 2 mol / L, and a sodium hydroxide solution with a concentration of 6 mol / L were prepared. Ammonia solution with a mass concentration of 25%-28% was diluted to 7 g / L, and 30 L of the corresponding concentration of ammonia solution was added to the reactor. Simultaneously, a sodium hydroxide solution with a concentration of 5 mol / L was added as a base solution, ensuring the pH of the base solution was 11.20. The stirring speed of the reactor was set to 750 rpm, and the stirring speed was reduced by 100 rpm for every 1 μm of particle growth after the particles reached 4 μm. The reactor temperature was maintained at 55°C. o The reaction process was kept constant throughout. Nickel salt, sodium hydroxide, and ammonia were simultaneously injected into the bottom solution, maintaining the flow rates of nickel salt at 1.2 L / h, sodium hydroxide at 0.8 L / h, and ammonia at 0.33 L / h. At the start of the reaction, the flow rate of the sodium hydroxide solution was adjusted to achieve a pH of 11.20, resulting in a suspension with Ni(OH)₂ solid particles having a D50 of 1-2 μm. After 2 hours of reaction, the flow rate of sodium hydroxide was reduced to lower the pH in the reactor by 0.2-0.4. Feeding was stopped when the particles grew to 10 μm, and the Ni(OH)₂ suspension was collected. The suspension was repeatedly washed and filtered until the filtrate pH was neutral. The washed filter cake was then filtered at 100°C. o After drying at C for 12 h, spherical nickel hydroxide with a D50 of 10 μm was obtained.

[0028] (2) Preparation of nickel-cobalt-manganese hydrotalcite nanosheets: Nickel, cobalt, and manganese salts were weighed according to a molar ratio of x:y:z = 3:1:1, and dissolved in deionized water to prepare salt solutions A with metal ion concentrations of 0.3 mol / L, 0.1 mol / L, and 0.1 mol / L, respectively. NaOH and Na₂CO₃ were dissolved in deionized water to prepare alkaline solutions B with NaOH concentration of 0.8 mol / L and Na₂CO₃ concentration of 0.2 mol / L. Equal volumes of salt solution A and alkaline solution B were simultaneously poured into a colloid mill at 3000 rpm for mixing. The resulting suspension was then heated at 85°C. o The filter cake was aged in a C water bath for 4 hours. After aging, it was washed with deionized water until the pH of the supernatant was 7. The washed filter cake was then heated at 80°C. o Nickel-cobalt-manganese hydrotalcite nanosheets were obtained by drying at C for 12 hours.

[0029] (3) Preparation of finished materials: according to the lithium nickel cobalt manganese oxide (LiNi) 0.80 Co 0.10 Mn 0.10In the O2 cathode material, the spherical nickel hydroxide prepared in step (1) and the nickel-cobalt-manganese hydrotalcite nanosheets prepared in step (2) were weighed according to the molar ratio of Ni, Co, and Mn. They were then mixed using a solid-phase ball mill at 300 rpm for 2 hours to obtain a spherical nickel hydroxide precursor coated with nickel-cobalt-manganese hydrotalcite. The hydrotalcite-coated nickel hydroxide precursor and lithium hydroxide were weighed according to a molar ratio of metal ions in the nickel-cobalt-manganese hydrotalcite nanosheet-coated spherical nickel hydroxide precursor to lithium ions in lithium hydroxide of 1:1.05, and mixed using a solid-phase ball mill at 200 rpm for 2 hours. The mixed sample was then subjected to a 5% oxygen atmosphere. o Heating rate increased to 470 °C / min o C, and sintered at that temperature for 6 h, followed by 5 o Heating rate increased to 780 °C / min o C, and sintered at a constant temperature for 20 h, finally cooled naturally to room temperature to obtain lithium nickel cobalt manganese oxide (LiNi). 0.80 Co 0.10 Mn 0.10 O2 cathode material.

[0030] The lithium nickel cobalt manganese oxide (LiNi) prepared in this embodiment 0.80 Co 0.10 Mn 0.10 The electrochemical performance of O2 sample assembled coin cells was tested at room temperature, and the results are shown in Table 1.

[0031] Comparative Example 1 (1) Preparation of spherical nickel-cobalt-manganese hydroxide precursor: Before the co-precipitation reaction begins, N2 is introduced to remove O2 from the deionized water in the reactor, and the N2 atmosphere is maintained during the reaction. Nickel sulfate, cobalt sulfate, and manganese sulfate are weighed according to the molar ratio of nickel, cobalt, and manganese as x:y:z = 90:5:5. A mixed salt solution with a metal ion concentration of 2 mol / L is prepared, an alkaline solution with a sodium hydroxide concentration of 6 mol / L is prepared, and an ammonia solution with a concentration of 6 g / L is prepared and filled into the overflow reactor as the reaction base liquid. The stirring speed of the overflow reactor is set to 600 rpm and kept constant throughout the reaction. The temperature of the overflow reactor is raised to 55°C. oC. The temperature remains constant throughout the reaction. A 2 mol / L salt solution is injected at a rate that fills the overflow reactor over 24 hours, and the injection rate remains constant throughout the reaction. Simultaneously, a 2 mol / L ammonia solution is injected to maintain the ammonia concentration in the reaction system at 6 g / L. A 6 mol / L sodium hydroxide solution is injected, and its flow rate is controlled to regulate the pH of the reaction solution in the overflow reactor. At the beginning of the reaction, the flow rate of the sodium hydroxide solution is controlled to maintain the pH of the reaction solution at 11.40. When Ni... 0.90 Co 0.05 Mn 0.05 Stop feeding when the (OH)₂ particle D50 reaches 10 μm. Repeatedly wash and filter the suspension until the filtrate pH reaches 7. Then, heat the washed filter cake at 100°C. o After drying at C for 12 h, spherical nickel-cobalt-manganese hydroxide (Ni) with a medium particle size D50 of 10 μm was obtained. 0.90 Co 0.05 Mn 0.05 (OH)2.

[0032] (2) Mixing the precursor with the lithium compound: Weigh out the nickel hydroxide, cobalt manganese, and lithium precursors Ni 0.90 Co 0.05 Mn 0.05 Weigh out the appropriate amounts of (OH)2 and lithium hydroxide according to the ratio of n(Li):n(Ni+Co+Mn) = 1.05:1, and mix them together by solid-phase ball milling at 200 rpm for 2 h to ensure uniform mixing.

[0033] (3) Preparation of finished materials: The mixed materials are heated in an oxygen atmosphere at 5°C. o Heating rate increased to 500 °C / min o Incubate at 5°C for 5 hours, then at 5°C. o Heating rate increased to 740 °C / min o The reaction was carried out at a constant temperature for 12 hours, then cooled to room temperature in the furnace, and the product was ground through a 400-mesh sieve to obtain LiNi. 0.90 Co 0.05 Mn 0.05 O2 cathode material.

[0034] The lithium nickel cobalt manganese oxide (LiNi) prepared in this comparative example 0.90 Co 0.05 Mn 0.05 The electrochemical performance of O2 sample assembled coin cells was tested at room temperature, and the results are shown in Table 1.

[0035] Comparative Example 2 (1) Preparation of spherical nickel-cobalt-manganese hydroxide precursor: Before the co-precipitation reaction, N2 was introduced to remove O2 from the deionized water in the reactor, and the N2 atmosphere was maintained during the reaction. Nickel sulfate, cobalt sulfate and manganese sulfate were weighed according to the molar ratio of nickel, cobalt and manganese as x : y : z = 80 : 10 : 10. A mixed salt solution with a metal ion concentration of 2 mol / L was prepared, an alkaline solution with a sodium hydroxide concentration of 6 mol / L was prepared, and an ammonia solution with a concentration of 5 g / L was prepared and filled into the overflow reactor as the reaction base liquid. The stirring speed of the overflow reactor was set to 600 rpm and kept constant throughout the reaction. The temperature of the overflow reactor was raised to 55°C. o C. The temperature remains constant throughout the reaction. A 2 mol / L salt solution is injected at a rate that fills the overflow reactor over 24 hours, and the injection rate remains constant throughout the reaction. Simultaneously, a 2 mol / L ammonia solution is injected to maintain the ammonia concentration in the reaction system at 5 g / L. A 6 mol / L sodium hydroxide solution is injected, and its flow rate is controlled to regulate the pH of the reaction solution in the overflow reactor. At the beginning of the reaction, the flow rate of the sodium hydroxide solution is controlled to maintain the pH of the reaction solution at 11.50. When Ni... 0.80 Co 0.10 Mn 0.10 Stop feeding when the (OH)₂ particle D50 reaches 10 μm. Repeatedly wash and filter the suspension until the filtrate pH reaches 7. Then, heat the washed filter cake at 100°C. o After drying at C for 12 h, spherical nickel-cobalt-manganese hydroxide (Ni) with a medium particle size D50 of 10 μm was obtained. 0.80 Co 0.10 Mn 0.10 (OH)2.

[0036] (2) Mixing the precursor with the lithium compound: Weigh out the nickel hydroxide, cobalt manganese, and lithium precursors Ni 0.80 Co 0.10 Mn 0.10 Weigh out the appropriate amounts of (OH)2 and lithium hydroxide according to the ratio of n(Li):n(Ni+Co+Mn) = 1.05:1, and mix them together by solid-phase ball milling at 200 rpm for 2 h to ensure uniform mixing.

[0037] (3) Preparation of finished materials: The mixed materials are heated in an oxygen atmosphere at 5°C. o Heating rate 470 °C / min o Incubate at 5°C for 6 hours, then at 5°C. o Heating rate increased to 780 °C / min o The reaction was carried out at a constant temperature for 20 h, then cooled to room temperature in the furnace, and the product was ground through a 400-mesh sieve to obtain lithium nickel cobalt manganese oxide (LiNi).0.80 Co 0.10 Mn 0.10 O2 cathode material.

[0038] The lithium nickel cobalt manganese oxide (LiNi) prepared in this comparative example 0.80 Co 0.10 Mn 0.10 The electrochemical performance of O2 sample assembled coin cells was tested at room temperature, and the results are shown in Table 1.

Claims

1. A method for preparing high-nickel lithium nickel cobalt manganese oxide cathode material, characterized in that, First, spherical nickel hydroxide particles and nickel-cobalt-manganese hydrotalcite nanosheets were prepared separately. Then, the nickel-cobalt-manganese hydrotalcite nanosheets were coated onto the surface of the spherical nickel hydroxide particles by solid-phase ball milling. Next, the nickel hydroxide coated with nickel-cobalt-manganese hydrotalcite was mixed evenly with a lithium compound and calcined at high temperature to obtain a high-nickel lithium nickel-cobalt-manganese oxide cathode material. The specific process steps are as follows: (1) Preparation of spherical nickel hydroxide particles: prepare a nickel salt solution with a concentration of 2-4 mol / L, an ammonia solution with a concentration of 2-4 mol / L, and a sodium hydroxide solution with a concentration of 5-7 mol / L, respectively, dilute ammonia water with a mass concentration of 25%-28% to 4-7 g / L, and add it to the reaction kettle, and at the same time, add a sodium hydroxide solution with a concentration of 5-7 mol / L as a bottom liquid, ensure that the pH of the bottom liquid is in the range of 11.20-11.60, the stirring speed of the reaction kettle is set to 600-750 rpm, and the temperature of the reaction kettle is maintained at 50-60 o C and remains unchanged throughout the process, inject nickel salt, sodium hydroxide and ammonia water into the bottom liquid at the same time, control the flow rate of the sodium hydroxide solution at the beginning of the reaction to make the pH of the reaction solution 11.20-11.60, at this time a suspension is generated, the solid particle size D50 of Ni(OH)2 in the suspension is 1-2 microns, after 6 hours of reaction, the flow rate of sodium hydroxide is reduced to lower the pH in the reaction kettle, the pH is lowered by 0.2-0.4, when the particles grow to 10 microns, stop feeding, collect the Ni(OH)2 suspension in the reaction kettle, repeatedly wash and filter the suspension until the filtrate is neutral, dry the washed filter cake at 80-100 o C for 12-16 hours to obtain uniform spherical nickel hydroxide with a D50 of 10-14 microns; (2) Preparation of nickel-cobalt-manganese hydrotalcite nanosheets: Nickel, cobalt, and manganese salts were weighed according to a molar ratio of 1-3:1-2:1 and dissolved in deionized water to prepare a salt solution A with a total metal ion concentration of 0.2-0.5 mol / L. NaOH and Na₂CO₃ were dissolved in deionized water to prepare an alkaline solution B with a NaOH concentration of 0.3-0.4 mol / L and a Na₂CO₃ concentration of 0.1-0.2 mol / L. Equal volumes of salt solution A and alkaline solution B were simultaneously poured into a colloid mill at a speed of 3000-4000 rpm for mixing. The resulting suspension was then heated at 80-100°C. o Aging in a C-water bath for 3-4 hours, followed by washing with deionized water, and then rinsing the washed filter cake at 80-120°C. o Drying at C for 10-12 hours yields nickel-cobalt-manganese hydrotalcite nanosheets; (3) Preparation of high-nickel lithium nickel cobalt manganese oxide cathode material: according to the lithium nickel cobalt manganese oxide LiNi1 x y Co x Mn y In the O2 cathode material, the spherical nickel hydroxide prepared in step (1) and the nickel-cobalt-manganese hydrotalcite nanosheets prepared in step (2) were weighed according to the molar ratio of Ni, Co, and Mn. The two were then mixed using a solid-phase ball mill at 200-400 rpm for 2-4 hours to obtain a nickel-cobalt-manganese hydrotalcite-coated spherical nickel hydroxide precursor. Based on a molar ratio of metal ions in the nickel-cobalt-manganese hydrotalcite-coated spherical nickel hydroxide precursor to lithium ions in the lithium compound of 1:1.01-1.05, the hydrotalcite-coated nickel hydroxide precursor and the lithium source were weighed and mixed using a solid-phase ball mill for 1-3 hours. The mixed sample was then in an oxygen atmosphere at 5-10... o Heating rate increased to 400-550 °C / min o C, and sinter at that temperature for 7-10 hours, followed by 5-10 o Heating rate increased to 740-780 °C / min o C, and sinter at a constant temperature for 10-18 hours, and finally cool naturally to room temperature to obtain lithium nickel cobalt manganese oxide cathode material.

2. The preparation method according to claim 1, characterized in that, The chemical composition of high-nickel lithium nickel cobalt manganese oxide is LiNi1. x y Co x Mn y O2, where 0.8≤1-xy≤0.9, 0<x≤0.15, 0<y≤0.10, and x+y+z=1.

3. The preparation method according to claim 1, characterized in that, The nickel salt mentioned in steps (1) and (2) is one or more of nickel sulfate, nickel chloride, nickel acetate or nickel nitrate.

4. The preparation method according to claim 1, characterized in that, The cobalt salt mentioned in step (2) is one or more of cobalt sulfate, cobalt chloride, cobalt acetate or cobalt nitrate.

5. The preparation method according to claim 1, characterized in that, The manganese salt mentioned in step (2) is one or more of manganese sulfate, manganese chloride, manganese acetate or manganese nitrate.

6. The preparation method according to claim 1, characterized in that, The lithium compound mentioned in step (3) is one or more of lithium hydroxide, lithium carbonate, or lithium nitrate.

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