A ternary composite doped high-nickel positive electrode material, a preparation method and application thereof

Abstract

This invention relates to the field of lithium-ion battery cathode material technology, specifically to a ternary composite doped high-nickel cathode material, its preparation method, and its application. The preparation method of the ternary composite doped high-nickel cathode material includes the following steps: preparing a solution A of nickel, cobalt, and manganese salts; preparing a solution B of aluminum, magnesium, and zirconium salts; in the presence of a precipitant, first performing a first co-precipitation reaction in solution A to generate a core precursor, then adding solution B to perform a second co-precipitation reaction to generate a shell precursor on the core surface, thus obtaining a core-shell structure precursor; mixing it with a lithium source and then performing gradient-segmented sintering, followed by post-treatment to obtain the final product. This invention, by concentrating the ternary composite doping elements in the shell layer, significantly improves the structural and thermal stability of the material while ensuring high capacity. The resulting cathode material exhibits excellent capacity retention and rate performance under high-pressure cycling conditions.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery cathode material technology, specifically to a ternary composite doped high-nickel cathode material, its preparation method, and its application. Background Technology

[0002] With the rapid development of new energy vehicles and the energy storage industry, the market has placed higher demands on the energy density, cycle life, and safety performance of lithium-ion batteries. High-nickel ternary cathode materials, due to their advantages such as high specific capacity and stable voltage platform, have become key materials for improving the energy density of lithium-ion batteries. However, as the nickel content increases, the crystal structure stability of high-nickel ternary materials decreases, making them prone to lattice distortion during cycling, leading to rapid capacity decay. Simultaneously, their thermal stability is poor, easily causing oxygen release under high temperature or overcharge conditions, triggering battery thermal runaway and posing safety hazards. Furthermore, the low ionic and electronic conductivity of high-nickel materials restricts further improvements in their rate performance.

[0003] To address the aforementioned issues, researchers typically employ doping and coating techniques to modify high-nickel ternary materials. However, traditional doping processes often involve solid-phase mixing, resulting in uneven distribution of dopant elements and limited modification effectiveness. Furthermore, the coating layer exhibits weak adhesion to the substrate material, making it prone to detachment during long-term cycling and hindering the sustained stability of the material. Therefore, achieving a uniform distribution of dopant elements and constructing a strong, structurally stable modification layer to synergistically improve the specific capacity, structural stability, thermal safety, and rate performance of high-nickel ternary cathode materials has become a pressing technical challenge. Summary of the Invention

[0004] This invention provides a ternary composite doped high-nickel cathode material, its preparation method, and its application, in order to solve the problem that it is difficult to synergistically improve the specific capacity, structural stability, thermal safety, and rate performance of existing high-nickel ternary cathode materials.

[0005] In a first aspect, the present invention provides a method for preparing a ternary composite doped high-nickel cathode material, comprising the following steps:

[0006] Preparation of core-shell structure precursor: Nickel salt, cobalt salt, and manganese salt are prepared into a mixed metal salt solution A; aluminum salt, magnesium salt, and zirconium salt are prepared into a mixed metal salt solution B; in the presence of a precipitant, solution A is first subjected to a first coprecipitation reaction to generate the core precursor; then solution B is added to the reaction system to carry out a second coprecipitation reaction to generate the shell precursor on the surface of the core precursor, thus obtaining the core-shell structure precursor; Lithification and sintering: The core-shell structure precursor is mixed with a lithium source and then subjected to gradient segmented sintering. After post-processing, a ternary composite doped high-nickel cathode material is obtained.

[0007] In one optional embodiment, the chemical formula of the ternary composite doped high-nickel cathode material is Li. e Ni x Co y Mn z M w O2, where x+y+z+w=1, 0.85≤x≤0.95, 0.02≤y≤0.08, 0.02≤z≤0.08, 0.002≤w≤0.008, 1.02≤e≤1.05, and M is a ternary composite doping element of Al, Mg and Zr.

[0008] In one optional embodiment, the molar ratio of Al, Mg, and Zr is (1.5~2.5):(0.5~1.5):(0.5~1.5), preferably 2:1:1.

[0009] In one optional embodiment, the particle size of the kernel precursor is 1~20 μm; And / or, the thickness of the shell precursor is 5~15nm.

[0010] In one optional embodiment, the concentration of the metal salt mixed solution A is 1.0~2.0 mol / L; And / or, the total concentration of the metal salt mixed solution B is 0.1~0.2 mol / L; And / or, the precipitant includes sodium hydroxide and / or potassium hydroxide; And / or, the conditions for the first coprecipitation reaction include: a reaction temperature of 50~65℃, a pH value of 10.0~11.5, a stirring rate of 300~500 r / min, and a reaction time of 15~20 h; And / or, the conditions for the second coprecipitation reaction include: a reaction temperature of 50~65℃, a pH value of 10.0~11.5, a stirring rate of 300~500r / min, and a reaction time of 5~10h.

[0011] In one optional embodiment, the gradient segmented sintering includes: first holding at 450~550℃ for 4~6h, then raising the temperature to 750~850℃ at a rate of 2~5℃ / min and holding for 10~15h, and finally cooling down to 250~350℃ at a rate of 1~2℃ / min and then naturally cooling to room temperature.

[0012] In one optional embodiment, the nickel salt includes at least one of nickel sulfate, nickel chloride, nickel nitrate, and nickel carbonate; And / or, the cobalt salt includes at least one of cobalt sulfate, cobalt chloride, cobalt nitrate, and cobalt carbonate; And / or, the manganese salt includes at least one of manganese sulfate, manganese chloride, manganese nitrate, and manganese carbonate; And / or, the aluminum salt includes at least one of aluminum sulfate, aluminum nitrate, aluminum chloride, and aluminum isopropoxide; And / or, the magnesium salt includes at least one of magnesium nitrate, magnesium sulfate, magnesium chloride, and magnesium acetate; And / or, the zirconium salt includes at least one of zirconium oxide, zirconium nitrate, zirconium sulfate, and zirconium acetate; And / or, the lithium source includes at least one of lithium hydroxide, lithium carbonate, lithium acetate, and lithium nitrate; And / or, the molar ratio of the core-shell structure precursor to the lithium source is 1:(1.02~1.05).

[0013] In one optional embodiment, both the first coprecipitation reaction and the second coprecipitation reaction are carried out under nitrogen protection; And / or, the gradient segmented sintering is performed in an oxygen atmosphere; And / or, the post-processing includes crushing and sieving steps.

[0014] Secondly, the present invention also provides a ternary composite doped high-nickel cathode material, which is prepared by the above-mentioned method for preparing ternary composite doped high-nickel cathode material.

[0015] Thirdly, the present invention also provides the application of the above-mentioned ternary composite doped high-nickel cathode material in new energy vehicle power batteries and energy storage lithium-ion batteries.

[0016] The technical solution provided by this invention has the following advantages: 1. This invention employs a stepwise co-precipitation process to first prepare an undoped core precursor, and then grow a shell precursor containing Al, Mg, and Zr ternary composite doping on its surface. This achieves uniform distribution of dopant elements in the shell and strong bonding with the core, effectively solving the problems of weak adhesion and easy detachment of traditional coating layers. By incorporating Al, Mg, and Zr into the shell, the advantages of Al are fully utilized. 3+ Suppressing lithium-nickel mixing, Mg 2+ Stable layered structure, Zr 4+ The synergistic effect of improved thermal stability, combined with the gradient segmented sintering process, effectively avoids lithium volatilization and crystal defects, resulting in a significant improvement in the ionic conductivity and rate performance of the material. The ternary composite doped high-nickel cathode material prepared by the method described in this invention exhibits excellent capacity retention and thermal stability under high-voltage cycling conditions, while also achieving high rate performance and excellent specific capacity.

[0017] 2. This invention specifies that the molar ratio of Al, Mg, and Zr is 2:1:1. By adjusting the proportion of the ternary doping elements, the Al... 3+ Mg 2+ Zr4+ It achieves the best synergistic effect in suppressing lithium-nickel mixing, stabilizing crystal structure, and improving thermal stability, and maximizes the modification effect of composite doping while avoiding capacity loss.

[0018] 3. The present invention controls the shell thickness within the range of 5~15nm, which ensures that the doped layer is thick enough to provide sufficient surface protection, while avoiding the obstruction of lithium-ion diffusion by an excessively thick shell, so that the material can achieve excellent cycle stability while maintaining high rate performance. Detailed Implementation

[0019] The following embodiments are provided to better understand the present invention, but the following embodiments do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the scope of protection of the present invention.

[0020] Unless otherwise specified, all experimental steps or conditions in the examples were performed according to conventional experimental procedures and conditions in the art. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0021] Example 1 This embodiment provides a method for preparing a ternary composite doped high-nickel cathode material, the specific steps of which are as follows: (1) Preparation of core-shell structure precursor: Nickel sulfate, cobalt sulfate, and manganese sulfate were dissolved in deionized water at a molar ratio of Ni:Co:Mn=90:5:5 to prepare a metal salt mixed solution A with a concentration of 1.5 mol / L; aluminum sulfate, magnesium nitrate, and zirconium oxide were dissolved in deionized water at a molar ratio of Al:Mg:Zr=2:1:1 to prepare a metal salt mixed solution B with a total concentration of 0.15 mol / L (where the total molar amount of aluminum, magnesium, and zirconium metal elements is 0.005:0.995 compared with the total molar amount of nickel, cobalt, and manganese metal elements in solution A); sodium hydroxide was dissolved in deionized water to prepare a precipitant solution with a sodium hydroxide concentration of 4 mol / L. Under nitrogen protection, deionized water was added to the reactor as the base liquid, the temperature was adjusted to 58℃, and the stirring rate was 400 r / min. Solution A and the precipitant solution were added to the reactor in a co-current dropwise manner, and the pH of the reaction system was controlled to be 11.0. After reacting for 18 h, the core precursor was generated, and the particle size D50 of the core precursor was 10 μm. The addition of solution A was stopped, and solution B and the precipitant solution were added to the reactor in a co-current dropwise manner. The reaction was continued for 8 h, and a shell precursor with a thickness of about 10 nm was generated on the surface of the core precursor. After the reaction was completed, the resulting slurry was filtered, washed, and dried at 120℃ for 12 h to obtain the core-shell structured precursor.

[0022] (2) Lithification and sintering: The core-shell structure precursor obtained in step (1) is mixed with lithium hydroxide at a molar ratio of Li:(Ni+Co+Mn+Al+Mg+Zr)=1.05:1 and placed in a sintering furnace; gradient segmented sintering is carried out under an oxygen atmosphere: first, the temperature is held at 500℃ for 5h, then the temperature is increased to 800℃ at a rate of 3℃ / min and held for 12h, then the temperature is decreased to 300℃ at a rate of 1.5℃ / min, and finally the temperature is naturally cooled to room temperature.

[0023] (3) Post-processing: The sintered product was crushed and passed through a 300-mesh sieve to obtain the ternary composite doped high-nickel cathode material Li. 1.05 (Ni 0.9 Co 0.05 Mn 0.05 ) 0.995 (Al 0.5 Mg 0.25 Zr 0.25 ) 0.005 O2.

[0024] Example 2 This embodiment provides a method for preparing a ternary composite doped high-nickel cathode material, the specific steps of which are as follows: (1) Preparation of core-shell structure precursor: Nickel sulfate, cobalt sulfate, and manganese sulfate were dissolved in deionized water at a molar ratio of Ni:Co:Mn=86:7:7 to prepare a metal salt mixed solution A with a concentration of 2.0 mol / L; aluminum sulfate, magnesium nitrate, and zirconium oxide were dissolved in deionized water at a molar ratio of Al:Mg:Zr=2.5:1.5:1.0 to prepare a metal salt mixed solution B with a total concentration of 0.2 mol / L (where the total molar amount of aluminum, magnesium, and zirconium metal elements is 0.008:0.992 compared with the total molar amount of nickel, cobalt, and manganese metal elements in solution A); sodium hydroxide and ammonia were dissolved in deionized water to prepare a precipitant solution with a sodium hydroxide concentration of 4 mol / L. Under nitrogen protection, deionized water was added to the reactor as the base liquid, the temperature was adjusted to 50℃, and the stirring rate was 300 r / min. Solution A and the precipitant solution were added to the reactor in a co-current dropwise manner, and the pH of the reaction system was controlled to be 10.0. After 20 h of reaction, the core precursor was generated, and the particle size D50 of the core precursor was 15 μm. The addition of solution A was stopped, and solution B and the precipitant solution were added to the reactor in a co-current dropwise manner. The reaction was continued for 10 h to generate a shell precursor with a thickness of about 15 nm on the surface of the core precursor. After the reaction was completed, the resulting slurry was filtered, washed, and dried at 120℃ for 12 h to obtain the core-shell structured precursor.

[0025] (2) Lithification and sintering: The core-shell structure precursor obtained in step (1) is mixed with lithium hydroxide at a molar ratio of Li:(Ni+Co+Mn+Al+Mg+Zr)=1.05:1 and placed in a sintering furnace; gradient segmented sintering is carried out under an oxygen atmosphere: first, the temperature is held at 500℃ for 5h, then the temperature is increased to 800℃ at a rate of 3℃ / min and held for 12h, then the temperature is decreased to 300℃ at a rate of 1.5℃ / min, and finally the temperature is naturally cooled to room temperature.

[0026] (3) Post-processing: The sintered product was crushed and passed through a 300-mesh sieve to obtain the ternary composite doped high-nickel cathode material Li. 1.05 (Ni 0.86 Co 0.07 Mn 0.07 ) 0.992 (Al 0.5 Mg 0.3 Zr 0.2 ) 0.008 O2.

[0027] Example 3 This embodiment provides a method for preparing a ternary composite doped high-nickel cathode material, the specific steps of which are as follows: (1) Preparation of core-shell structure precursor: Nickel sulfate, cobalt sulfate, and manganese sulfate were dissolved in deionized water at a molar ratio of Ni:Co:Mn=94:3:3 to prepare a metal salt mixed solution A with a concentration of 1.0 mol / L; aluminum sulfate, magnesium nitrate, and zirconium oxide were dissolved in deionized water at a molar ratio of Al:Mg:Zr=1.5:1.0:1.5 to prepare a metal salt mixed solution B with a total concentration of 0.1 mol / L (where the total molar amount of aluminum, magnesium, and zirconium metal elements is 0.002:0.998 compared with the total molar amount of nickel, cobalt, and manganese metal elements in solution A); sodium hydroxide and ammonia were dissolved in deionized water to prepare a precipitant solution with a sodium hydroxide concentration of 4 mol / L. Under nitrogen protection, deionized water was added to the reactor as the base liquid, the temperature was adjusted to 65℃, and the stirring rate was 500 r / min. Solution A and the precipitant solution were added to the reactor in a co-current dropwise manner, and the pH of the reaction system was controlled to be 11.5. After reacting for 15 h, the core precursor was generated, and the particle size D50 of the core precursor was 5 μm. The addition of solution A was stopped, and solution B and the precipitant solution were added to the reactor in a co-current dropwise manner. The reaction was continued for 5 h, and a shell precursor with a thickness of about 5 nm was generated on the surface of the core precursor. After the reaction was completed, the resulting slurry was filtered, washed, and dried at 120℃ for 12 h to obtain the core-shell structured precursor.

[0028] (2) Lithification and sintering: The core-shell structure precursor obtained in step (1) is mixed with lithium hydroxide at a molar ratio of Li:(Ni+Co+Mn+Al+Mg+Zr)=1.05:1 and placed in a sintering furnace; gradient segmented sintering is carried out under an oxygen atmosphere: first, the temperature is held at 450℃ for 6h, then the temperature is increased to 750℃ at a rate of 2℃ / min and held for 15h, then the temperature is decreased to 350℃ at a rate of 1℃ / min, and finally the temperature is naturally cooled to room temperature.

[0029] (3) Post-processing: The sintered product was crushed and passed through a 300-mesh sieve to obtain the ternary composite doped high-nickel cathode material Li. 1.05 (Ni 0.94 Co 0.03 Mn 0.03 ) 0.998 (Al 0.375 Mg 0.25 Zr 0.375 ) 0.002 O2.

[0030] Example 4 This embodiment provides a method for preparing a ternary composite doped high-nickel cathode material, the specific steps of which are as follows: (1) Preparation of core-shell structure precursor: Nickel sulfate, cobalt sulfate, and manganese sulfate were dissolved in deionized water at a molar ratio of Ni:Co:Mn=88:7:5 to prepare a metal salt mixed solution A with a concentration of 1.8 mol / L; aluminum sulfate, magnesium nitrate, and zirconium oxide were dissolved in deionized water at a molar ratio of Al:Mg:Zr=2:1:1 to prepare a metal salt mixed solution B with a total concentration of 0.12 mol / L (where the total molar amount of aluminum, magnesium, and zirconium metal elements is 0.005:0.995 compared with the total molar amount of nickel, cobalt, and manganese metal elements in solution A); sodium hydroxide and ammonia were dissolved in deionized water to prepare a precipitant solution with a sodium hydroxide concentration of 4 mol / L. Under nitrogen protection, deionized water was added to the reactor as the base liquid, the temperature was adjusted to 55℃, and the stirring rate was 350 r / min. Solution A and the precipitant solution were added to the reactor in a co-current dropwise manner, and the pH of the reaction system was controlled to be 10.8. After 18 h of reaction, the core precursor was generated, and the particle size D50 of the core precursor was 12 μm. The addition of solution A was stopped, and solution B and the precipitant solution were added to the reactor in a co-current dropwise manner. The reaction was continued for 7 h, and a shell precursor with a thickness of about 8 nm was generated on the surface of the core precursor. After the reaction was completed, the resulting slurry was filtered, washed, and dried at 120℃ for 12 h to obtain the core-shell structured precursor.

[0031] (2) Lithification and sintering: The core-shell structure precursor obtained in step (1) is mixed with lithium hydroxide at a molar ratio of Li:(Ni+Co+Mn+Al+Mg+Zr)=1.05:1 and placed in a sintering furnace; gradient segmented sintering is carried out under an oxygen atmosphere: first, the temperature is held at 550℃ for 4h, then the temperature is increased to 850℃ at a rate of 5℃ / min and held for 10h, then the temperature is decreased to 250℃ at a rate of 2℃ / min, and finally the temperature is naturally cooled to room temperature.

[0032] (3) Post-processing: The sintered product was crushed and passed through a 300-mesh sieve to obtain the ternary composite doped high-nickel cathode material Li. 1.05 (Ni 0.88 Co 0.07 Mn 0.05 ) 0.995 (Al 0.5 Mg 0.25 Zr 0.25 ) 0.005 O2.

[0033] Comparative Example 1 This comparative example provides a method for preparing a high-nickel ternary cathode material. The difference between this method and Example 1 is that Al, Mg, and Zr doping is not performed, while other conditions are the same as in Example 1.

[0034] Comparative Example 2 This comparative example provides a method for preparing a high-nickel ternary cathode material. The difference between this method and Example 1 is that only Al doping is performed, and Mg and Zr doping is not performed. Other conditions are the same as in Example 1.

[0035] Comparative Example 3 This comparative example provides a method for preparing a high-nickel ternary cathode material. The difference between this method and Example 1 is that nickel sulfate, cobalt sulfate, manganese sulfate, aluminum sulfate, magnesium nitrate, and zirconium oxide are mixed simultaneously and directly prepared into a mixed solution. The precursor with overall doping is prepared through a one-step co-precipitation reaction. Other conditions are the same as in Example 1.

[0036] Comparative Example 4 This comparative example provides a method for preparing a high-nickel ternary cathode material. The difference between this method and Example 1 is that step (2) uses a conventional sintering process: the core-shell precursor is mixed with a lithium source, and then heated directly to 800°C at a rate of 3°C / min under an oxygen atmosphere and held for 12 hours, and then naturally cooled to room temperature. That is, gradient segmented sintering is not used, and other conditions are the same as in Example 1.

[0037] Test case The positive electrode materials prepared in each embodiment and comparative example were used as active materials, and mixed with conductive carbon black and polyvinylidene fluoride (PVDF) at a mass ratio of 90:5:5. N-methylpyrrolidone (NMP) was added to prepare a slurry, which was then uniformly coated on aluminum foil. The surface loading of the active material was 10 mg / cm². 2 After drying, rolling, and stamping, the positive electrode sheet is made. Using lithium metal sheet as negative electrode, polypropylene porous membrane as separator, and 1 mol / L LiPF6 EC / DMC / DEC (volume ratio 1:1:1) solution as electrolyte, CR2032 coin cell lithium-ion battery is assembled in an argon glove box.

[0038] Cyclic performance test: At 25℃, the assembled button cells were charged and discharged at a rate of 1C within the voltage range of 2.8-4.3V. The specific capacity of the first discharge and the specific capacity of the discharge after 500 cycles were recorded, and the capacity retention rate was calculated. The results are shown in Table 1.

[0039] Thermal stability test: The positive electrode materials prepared in each example and comparative example were disassembled under full charge (charged to 4.3V) to obtain electrode sheets, and active material powder was scraped off. The thermal stability was tested using differential scanning calorimetry (DSC) with a heating rate of 10℃ / min and a temperature range of 50~350℃. The exothermic peak temperature was recorded, and the results are shown in Table 1.

[0040] Rate performance test: At 25℃, the assembled button cells were charged and discharged at rates of 0.2C, 1C and 5C within the voltage range of 2.8-4.3V. The discharge specific capacity at each rate was recorded, and the results are shown in Table 1.

[0041] Table 1 Electrochemical performance of the cathode materials obtained in the examples and comparative examples

[0042] Based on the above test results, it can be seen that the present invention significantly improves the comprehensive electrochemical performance of high-nickel ternary cathode materials through the synergistic effect of Al, Mg, and Zr ternary composite doping, core-shell structure design, and gradient segmented sintering process. Compared with Comparative Example 1 (undoped), Example 1, while maintaining a comparable initial discharge specific capacity, increased the capacity retention rate after 500 cycles from 72.3% to 89.2%, the exothermic peak temperature from 218℃ to 265℃, and the 5C / 0.2C rate performance from 62.1% to 75.6%, demonstrating that ternary composite doping effectively suppresses lithium-nickel mixing, stabilizes the crystal structure, and improves thermal safety. Compared with Comparative Example 2 (single Al doping) and Comparative Example 3 (overall doping), the cycle retention rate of Example 1 is 10.6 percentage points and 8.0 percentage points higher, respectively, and the rate performance is 9.8 percentage points and 6.0 percentage points higher, respectively, indicating that the core-shell structure design concentrates the doping elements in the shell layer, significantly enhancing the surface structure stability while ensuring the high capacity of the core. Compared with Comparative Example 4 (conventional sintering), Example 1 showed a 5.7 percentage point higher cycle retention rate and a 4.2 percentage point higher rate performance, confirming that gradient segmented sintering reduced crystal defects and optimized lithium-ion diffusion channels.

[0043] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a ternary composite doped high-nickel cathode material, characterized in that, Includes the following steps: Preparation of core-shell structure precursors: Prepare a mixed metal salt solution A by mixing nickel salt, cobalt salt, and manganese salt; Aluminum salt, magnesium salt and zirconium salt were prepared into a mixed metal salt solution B; in the presence of a precipitant, solution A was first subjected to a first coprecipitation reaction to generate a core precursor; then solution B was added to the reaction system to carry out a second coprecipitation reaction to generate a shell precursor on the surface of the core precursor, thus obtaining a core-shell structure precursor. Lithification and sintering: The core-shell structure precursor is mixed with a lithium source and then subjected to gradient segmented sintering. After post-processing, a ternary composite doped high-nickel cathode material is obtained.

2. The preparation method according to claim 1, characterized in that, The chemical formula of the ternary composite doped high-nickel cathode material is Li. e Ni x Co y Mn z M w O2, where x+y+z+w=1, 0.85≤x≤0.95, 0.02≤y≤0.08, 0.02≤z≤0.08, 0.002≤w≤0.008, 1.02≤e≤1.05, and M is a ternary composite doping element of Al, Mg and Zr.

3. The preparation method according to claim 2, characterized in that, The molar ratio of Al, Mg, and Zr is (1.5~2.5):(0.5~1.5):(0.5~1.5), preferably 2:1:

1.

4. The preparation method according to claim 1 or 2, characterized in that, The particle size of the core precursor is 1~20μm; And / or, the thickness of the shell precursor is 5~15nm.

5. The preparation method according to claim 1 or 2, characterized in that, The concentration of the metal salt mixed solution A is 1.0~2.0 mol / L; And / or, the total concentration of the metal salt mixed solution B is 0.1~0.2 mol / L; And / or, the precipitant includes sodium hydroxide and / or potassium hydroxide; And / or, the conditions for the first coprecipitation reaction include: a reaction temperature of 50~65℃, a pH value of 10.0~11.5, a stirring rate of 300~500 r / min, and a reaction time of 15~20 h; And / or, the conditions for the second coprecipitation reaction include: a reaction temperature of 50~65℃, a pH value of 10.0~11.5, a stirring rate of 300~500r / min, and a reaction time of 5~10h.

6. The preparation method according to claim 1 or 2, characterized in that, The gradient segmented sintering process includes: first holding at 450~550℃ for 4~6h, then raising the temperature to 750~850℃ at a rate of 2~5℃ / min and holding for 10~15h, and finally cooling down to 250~350℃ at a rate of 1~2℃ / min and then naturally cooling to room temperature.

7. The preparation method according to claim 1 or 2, characterized in that, The nickel salt includes at least one of nickel sulfate, nickel chloride, nickel nitrate, and nickel carbonate; And / or, the cobalt salt includes at least one of cobalt sulfate, cobalt chloride, cobalt nitrate, and cobalt carbonate; And / or, the manganese salt includes at least one of manganese sulfate, manganese chloride, manganese nitrate, and manganese carbonate; And / or, the aluminum salt includes at least one of aluminum sulfate, aluminum nitrate, aluminum chloride, and aluminum isopropoxide; And / or, the magnesium salt includes at least one of magnesium nitrate, magnesium sulfate, magnesium chloride, and magnesium acetate; And / or, the zirconium salt includes at least one of zirconium oxide, zirconium nitrate, zirconium sulfate, and zirconium acetate; And / or, the lithium source includes at least one of lithium hydroxide, lithium carbonate, lithium acetate, and lithium nitrate; And / or, the molar ratio of the core-shell structure precursor to the lithium source is 1:(1.02~1.05).

8. The preparation method according to claim 1 or 2, characterized in that, Both the first and second coprecipitation reactions were carried out under nitrogen protection. And / or, the gradient segmented sintering is performed in an oxygen atmosphere; And / or, the post-processing includes crushing and sieving steps.

9. A ternary composite doped high-nickel cathode material, characterized in that, It is prepared by the method for preparing ternary composite doped high-nickel cathode material according to any one of claims 1 to 8.

10. The application of the ternary composite doped high-nickel cathode material according to claim 9 in power batteries for new energy vehicles and energy storage lithium-ion batteries.

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