Quick-charging type high-voltage positive electrode material and preparation method thereof

Abstract

The invention discloses a fast-charging high-voltage positive electrode material and a preparation method thereof, and the preparation method comprises the following steps: 1, carrying out a co-precipitation reaction on a first feed liquid containing nickel ions, cobalt ions and manganese ions to obtain a slurry I; step 2, adding a second feed liquid containing nickel salt, cobalt salt and manganese salt into the slurry I, and carrying out a co-precipitation reaction to obtain slurry II; step 3, adding a third feed liquid containing nickel salt, cobalt salt and manganese salt into the slurry II, and carrying out a co-precipitation reaction to obtain slurry III; 4, the gradient cobalt-rich precursor, a lithium source and a high-entropy doping source are mixed and then subjected to calcination treatment, and a doped gradient cobalt-rich matrix is obtained; and fifthly, the surface of the doped gradient cobalt-rich matrix is coated with a coating, and then calcination treatment is conducted. Through the gradient multi-element doping technology, the doping uniformity of elements in the inner layer and the outer layer of the material is guaranteed, and the rate capability and the high-temperature stability of the material are remarkably improved.

Description

A fast-charging high-voltage cathode material and its preparation method Technical Field

[0001] This invention belongs to the field of battery technology, specifically relating to a fast-charging high-voltage cathode material and its preparation method. Background Technology

[0002] With the rapid development of the lithium-ion battery industry, high-energy-density lithium-ion batteries are increasingly favored by the market. However, the problem of insufficient battery life and long charging time of high-energy lithium batteries has always been a source of anxiety. Therefore, it is crucial to develop a high-energy / fast-charging ternary lithium battery. How to improve the energy density of single-crystal ternary cathode materials while taking into account fast charging capability is an urgent problem to be solved in battery technology.

[0003] Some researchers have improved the energy density and stability of battery cathode materials by optimizing the morphology of single-crystal particles and using high-entropy element doping coating technology. While these techniques effectively improve the energy density of the materials, other properties still have certain shortcomings. For example, the mobility of lithium ions decreases significantly under high voltage, and the interfacial side reactions between high-surface-area materials and electrolytes increase, resulting in poor kinetic performance of the cathode material during charge and discharge, and poor cycle performance under high-voltage, high-rate charging. Consequently, the battery cells cannot meet the higher demands of modern consumers. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a gradient cobalt-rich doping and wet in-situ coating technique. First, a cobalt-gradient precursor material is designed and developed, featuring a cobalt-rich outer layer and a low-cobalt inner layer. This structure significantly improves the layered structure of the NCM, further enhancing the lithium-ion kinetics under high voltage and reducing lithium-ion diffusion resistance. Next, Ti, Mg, Al, and Zr are doped into the inner and outer layers of the precursor to stabilize the material's structure under high voltage and reduce interfacial residual alkali. Finally, a wet in-situ coating technique ensures uniform coating, further improving the lithium-ion diffusion rate and reducing the interfacial impedance of the cathode material. This results in a fast-charging 4.50V high-voltage single-crystal ternary cathode material. This product not only has a high specific capacity but also significantly enhanced cycle and rate performance, significantly improving the energy density of the entire battery. This invention is achieved using the following technical solution: a method for preparing a fast-charging high-voltage positive electrode material, comprising the following steps: Step 1: co-precipitating a first solution containing nickel ions, cobalt ions, and manganese ions to obtain slurry I; the weight of cobalt in the first solution is 5%~10% of the total weight of nickel, cobalt, and manganese; Step 2: adding a second solution containing nickel salts, cobalt salts, and manganese salts to slurry I to conduct a co-precipitation reaction to obtain slurry II, the weight of cobalt in the second solution being 20%~28% of the total weight of nickel, cobalt, and manganese; Step 3: adding a solution containing nickel... A third solution of salt, cobalt salt, and manganese salt undergoes a co-precipitation reaction to obtain slurry III, wherein the weight of cobalt in the third solution is 30%~35% of the total weight of nickel, cobalt, and manganese; after aging and drying the slurry III, a gradient cobalt-rich precursor is obtained; the first, second, and / or third solutions contain at least one of titanium ions, magnesium ions, zirconium ions, and magnesium ions; step four: the gradient cobalt-rich precursor, lithium source, and high-entropy doping source are mixed and then calcined to obtain a doped gradient cobalt-rich matrix; step five: a coating containing Li, Y, Zr, and P is coated on the surface of the doped gradient cobalt-rich matrix, and then calcined to obtain the fast-charging high-voltage cathode material.

[0005] Optionally, in step one, the first liquid contains titanium ions, and the weight of titanium in the first liquid is 0.05%-0.10% of the total weight of nickel, cobalt, and manganese; in step two, the second liquid contains magnesium ions, and the weight of magnesium in the second liquid is 0.03%-0.06% of the total weight of nickel, cobalt, and manganese; in step three, the third liquid contains zirconium ions and aluminum ions, and the weight of zirconium in the third liquid is 0.2%-0.3% of the total weight of nickel, cobalt, and manganese, and the weight of aluminum is 0.1%-0.2% of the total weight of nickel, cobalt, and manganese.

[0006] Optionally, a complexing agent and a precipitant are added when the first, second, and third feed solutions are co-precipitated; the complexing agent is at least one of ammonia, ammonium bisulfate, and EDTA; and the precipitant is at least one of sodium hydroxide and sodium carbonate.

[0007] Optionally, in step four, the calcination is carried out in an oxygen atmosphere at a temperature of 900-960℃ for a holding time of 9-12 hours.

[0008] Optionally, in step four, the molar ratio of lithium in the lithium source to nickel, cobalt, and manganese in the gradient cobalt-rich precursor is 1.04-1.07; the high-entropy doping source includes WO3, Nb2O5, and Y2O3; and the molar ratio of the high-entropy doping source to the lithium source is 0.3% to 0.5%.

[0009] Optionally, in step five, the temperature is 800-900℃ and the holding time is 4-8 hours.

[0010] Optionally, the method for coating the surface of the doped gradient cobalt-rich substrate with a coating containing Li, Y, Zr and P is to place the doped gradient cobalt-rich substrate in a solution containing Li, Y, Zr and P, and then dry it at 150~250℃ for 3-4 hours.

[0011] Optionally, the molar ratio of Li:Y:Zr:P in the solution containing Li, Y, Zr and P is 1.2-1.4:0.2-0.4:1.5-2.0:2.5-3.5.

[0012] This invention also proposes a fast-charging high-voltage cathode material prepared by the above preparation method.

[0013] The present invention also proposes the application of the above-mentioned fast-charging high-voltage cathode material in lithium batteries.

[0014] The present invention has the following beneficial effects: The gradient multi-element doping precursor technology provided by the present invention ensures the uniformity of element doping in the inner and outer layers of the material. The high concentration of Ti and Mg elements in the inner layer stabilizes the layered structure through strong Ti-O and Mg-O bonds, reducing lattice distortion during charging and discharging. The Al / Zr doping in the outer layer reduces surface residual alkali, improves lithium-ion diffusion kinetics, suppresses side reactions between the interface and the electrolyte, and significantly improves the rate performance and high-temperature stability of the material. The cobalt-rich gradient precursor preparation technology provided by the present invention can further improve the lithium-ion migration rate and reduce lithium-ion diffusion resistance by designing a cobalt-rich outer layer, which greatly improves the kinetic performance of the material. The present invention optimizes the uniformity of the coating layer and interface transport through in-situ wet coating technology. The fast ion material (LYZP) coating layer can significantly improve the lithium-ion diffusion rate, and the uniform fast ion coating layer can greatly improve the kinetic performance of the cathode material under high voltage. The present invention improves the capacity, rate performance and cycle stability of the cathode material under high voltage system, and has better cycle stability and rate performance while achieving high capacity, significantly improving the energy density of the battery. Detailed Implementation

[0015] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0016] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0017] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0018] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0019] This invention proposes a method for preparing a fast-charging high-voltage cathode material, comprising the following steps: Step 1: A first solution containing nickel ions, cobalt ions, and manganese ions is subjected to a co-precipitation reaction to obtain slurry I; the weight of cobalt in the first solution is 5%~10% of the total weight of nickel, cobalt, and manganese; Step 2: A second solution containing nickel salt, cobalt salt, and manganese salt is added to slurry I to undergo a co-precipitation reaction to obtain slurry II; the weight of cobalt in the second solution is 20%~28% of the total weight of nickel, cobalt, and manganese; Step 3: A second solution containing nickel salt, cobalt salt, and manganese salt is added to slurry II to obtain slurry II. The third solution of manganese salt undergoes a co-precipitation reaction to obtain slurry III, wherein the weight of cobalt in the third solution is 30%~35% of the total weight of nickel, cobalt and manganese; after aging and drying the slurry III, a gradient cobalt-rich precursor is obtained; the first, second and / or third solutions contain at least one of titanium ions, magnesium ions, zirconium ions and magnesium ions; step four: the gradient cobalt-rich precursor, lithium source and high-entropy doping source are mixed and calcined to obtain a doped gradient cobalt-rich matrix; step five: a coating containing Li, Y, Zr and P is coated on the surface of the doped gradient cobalt-rich matrix, and then calcined to obtain the fast-charging high-voltage cathode material.

[0020] The term "gradient cobalt enrichment" in the cobalt-rich precursor refers to a gradual increase in cobalt content from the inside out. During the co-precipitation process in steps one through three, the weight of cobalt in the raw materials accounts for 5%–10%, 20%–28%, and 30%–35% of the total weight of nickel, cobalt, and manganese, respectively. Therefore, the cobalt content in the resulting precursor gradually increases from the inside out. This cobalt-rich gradient design can enhance the migration rate of lithium ions, improve their kinetic properties, and thus improve the rate stability of the material.

[0021] This invention provides a fast-charging high-voltage cathode material, its preparation method, and its applications. By optimizing the selection of doping elements in the inner and outer layers of the precursor bulk phase, optimal doping technology for both the inner and outer layers of the cathode material is achieved. On one hand, the inner layer (Mg / Ti-O bond stabilizes the layered structure) enhances the material's structural stability; on the other hand, the outer layer doping (Al / Zr doping reduces surface residual alkali) reduces surface residual alkali and improves the material's interface stability. Furthermore, by designing a cobalt-rich gradient in the precursor, the lithium-ion migration rate is significantly improved, resulting in enhanced lithium-ion kinetics and thus improved rate stability. Finally, a fast-ion conductive layer is constructed at the cathode material interface using a wet in-situ coating technique, further reducing the material's interface impedance and increasing the lithium-ion diffusion rate. This material not only effectively solves the problem of poor cycle performance of full batteries under ultra-high voltage but also significantly improves the kinetics and fast-charging capability of the cathode material, significantly increasing the battery's energy density and fast-charging ability.

[0022] Example 1 (1) Nickel sulfate, cobalt sulfate, manganese sulfate, and titanium salt (TiCl4) were dissolved in water at a molar ratio of Ni:Co:Mn:Ti of 60:10:29.9:0.1, with a cation concentration of 1.8 mol / L, to prepare the first solution. 0.5 M EDTA was used as a complexing agent and sodium hydroxide solution was used as a precipitant to carry out a co-precipitation reaction on the first solution.

[0023] (2) Overflow the slurry I obtained from the coprecipitation reaction into the secondary reactor. Add the second liquid to the secondary reactor. The second liquid includes nickel sulfate, cobalt sulfate, manganese sulfate, and magnesium sulfate. The molar ratio of Ni:Co:Mn:Mg is 60:20:19.9:0.1. The cation concentration of the second liquid is 1.8 mol / L. The volume ratio of the second liquid to slurry I is 1:1. Then add the complexing agent, precipitant and alkaline solution mentioned above to carry out the coprecipitation reaction.

[0024] (3) The slurry II obtained from the co-precipitation reaction is overflowed into the third-stage reactor. The third liquid is added into the third-stage reactor. The third liquid contains nickel sulfate, cobalt sulfate, manganese sulfate, zirconium sulfate and aluminum sulfate. The molar ratio of Ni:Co:Mn:Zr:Al is 60:30:9.5:0.2:0.3, the cation concentration is 1.8mol / L, and the volume ratio of the third liquid to slurry II is 1:1. Complexing agent, precipitant and alkaline solution are added to carry out the co-precipitation reaction. The slurry III obtained from the co-precipitation reaction is overflowed into the aging tank and aged. After aging, it is dried at 130℃ for 5 h to obtain a multi-element gradient doped and cobalt-rich ternary precursor.

[0025] (4) A ternary precursor with multi-element gradient doping and cobalt richness, a high-entropy doping source (WO3, Nb2O5, Y2O3) is mixed with lithium hydroxide, wherein the molar ratio of total nickel, cobalt and manganese: W: Nb: Y is 1000:0.1:0.2:0.1, and further sintered by high-temperature solid-state method to obtain a ternary material matrix I with gradient element doping and cobalt richness; wherein the molar ratio of lithium element in lithium hydroxide and nickel, cobalt and manganese element in ternary precursor is 1.05; the first calcination treatment is carried out in an oxygen atmosphere, and the process conditions of the first calcination treatment include: calcination temperature 950℃, holding time 10 h.

[0026] (5) The ternary material matrix I was dispersed in an ethanol solution containing LiNO3, Y(NO3)3·6H2O, ZrOCl2·8H2O, and NH4H2PO and mixed evenly. The mass ratio of the ternary material matrix I to the ethanol solvent of Li, Y, Zr, and P was 100:1:1.2:6.1:3.8:50. The matrix was dried at 200℃ for 3 hours, then sintered at high temperature and calcined at 850℃ for 6 hours to form a NASICON-type (LYZP) coating on the surface of the ternary material matrix I. The coating structure is Li 1.3 Y0.3 Zr 1.7 (PO4)3 yields a fast-charging high-voltage cathode material.

[0027] Example 2 (1) Nickel sulfate, cobalt sulfate and manganese sulfate were dissolved in water at a molar ratio of Ni:Co:Mn of 60:10:30, with a cation concentration of 1.8 mol / L, to prepare the first solution; 0.5 M EDTA was used as a complexing agent and sodium hydroxide solution was used as a precipitant to carry out a co-precipitation reaction on the first solution.

[0028] (2) Overflow the slurry I obtained from the coprecipitation reaction into the secondary reactor. Add the second liquid to the secondary reactor. The second liquid includes nickel sulfate, cobalt sulfate, manganese sulfate, and the molar ratio of Ni:Co:Mn is 60:20:20. The cation concentration of the second liquid is 1.8 mol / L. The volume ratio of the second liquid to slurry I is 1:1. Then add the complexing agent, precipitant and alkaline solution mentioned above to carry out the coprecipitation reaction.

[0029] (3) The slurry II obtained from the coprecipitation reaction is overflowed into the third-stage reactor. The third liquid is added into the third-stage reactor. The third liquid contains nickel sulfate, cobalt sulfate, manganese sulfate, zirconium sulfate, aluminum sulfate, titanium tetrachloride, and magnesium sulfate. The molar ratio of Ni:Co:Mn:Zr:Al:Ti:Mg is 60:30:9.3:0.2:0.3:0.1:0.1, the cation concentration is 1.8 mol / L, and the volume ratio of the third liquid to slurry II is 1:1. The complexing agent, precipitant, and alkaline solution are added to carry out the coprecipitation reaction. The slurry III obtained from the coprecipitation reaction is overflowed into the aging reactor and aged. Then it is dried at 130℃ for 5 h to obtain a multi-element gradient doped and cobalt-rich ternary precursor.

[0030] (4) A ternary precursor with multi-element gradient doping and cobalt richness, a high-entropy doping source (WO3, Nb2O5, Y2O3) is mixed with lithium hydroxide, wherein the molar ratio of total nickel, cobalt and manganese: W: Nb: Y is 1000:0.1:0.2:0.1, and further sintered by high-temperature solid-state method to obtain a ternary material matrix I with gradient element doping and cobalt richness; wherein the molar ratio of lithium element in lithium hydroxide and nickel, cobalt and manganese element in ternary precursor is 1.05; the first calcination treatment is carried out in an oxygen atmosphere, and the process conditions of the first calcination treatment include: calcination temperature 950℃, holding time 10 h.

[0031] (5) The ternary material matrix I was dispersed in an ethanol solution containing LiNO3, Y(NO3)3·6H2O, ZrOCl2·8H2O, and NH4H2PO and mixed evenly. The mass ratio of the ternary material matrix I to the ethanol solvent of Li, Y, Zr, and P was 100:1:1.2:6.1:3.8:50. The matrix was dried at 200℃ for 3 hours, then sintered at high temperature and calcined at 850℃ for 6 hours to form a NASICON-type (LYZP) coating on the surface of the ternary material matrix I. The coating structure is Li 1.3 Y 0.3 Zr 1.7 (PO4)3 yields a fast-charging high-voltage cathode material.

[0032] Example 3 (1) Nickel sulfate, cobalt sulfate, manganese sulfate, and titanium salt (TiCl4) were dissolved in water at a molar ratio of Ni:Co:Mn:Ti of 60:10:29.95:0.05, with a cation concentration of 1.8 mol / L, to prepare the first solution. 0.5 M EDTA was used as a complexing agent and sodium hydroxide solution was used as a precipitant to carry out a co-precipitation reaction on the first solution.

[0033] (2) Overflow the slurry I obtained from the coprecipitation reaction into the secondary reactor. Add the second liquid to the secondary reactor. The second liquid includes nickel sulfate, cobalt sulfate, manganese sulfate, and magnesium sulfate. The molar ratio of Ni:Co:Mn:Mg is 60:20:19.95:0.05. The cation concentration of the second liquid is 1.8 mol / L. The volume ratio of the second liquid to slurry I is 1:1. Then add the complexing agent, precipitant and alkaline solution mentioned above to carry out the coprecipitation reaction.

[0034] (3) The slurry II obtained from the coprecipitation reaction is overflowed into the third-stage reactor. The third liquid is added into the third-stage reactor. The third liquid contains nickel sulfate, cobalt sulfate, manganese sulfate, zirconium sulfate and aluminum sulfate. The molar ratio of Ni:Co:Mn:Zr:Al is 60:30:9.75:0.1:0.15, the cation concentration is 1.8mol / L, and the volume ratio of the third liquid to slurry II is 1:1. Complexing agent, precipitant and alkaline solution are added to carry out coprecipitation reaction. The slurry III obtained from the coprecipitation reaction is overflowed into the aging tank and aged. After aging, it is dried at 130℃ for 5 h to obtain a multi-element gradient doped and cobalt-rich ternary precursor.

[0035] (4) A ternary precursor with multi-element gradient doping and cobalt richness, a high-entropy doping source (WO3, Nb2O5, Y2O3) is mixed with lithium hydroxide, wherein the molar ratio of total nickel, cobalt and manganese: W: Nb: Y is 1000:0.1:0.2:0.1, and further sintered by high-temperature solid-state method to obtain a ternary material matrix I with gradient element doping and cobalt richness; wherein the molar ratio of lithium element in lithium hydroxide and nickel, cobalt and manganese element in ternary precursor is 1.05; the first calcination treatment is carried out in an oxygen atmosphere, and the process conditions of the first calcination treatment include: calcination temperature 950℃, holding time 10 h.

[0036] (5) The ternary material matrix I was dispersed in an ethanol solution containing LiNO3, Y(NO3)3·6H2O, ZrOCl2·8H2O, and NH4H2PO and mixed evenly. The mass ratio of the ternary material matrix I to the ethanol solvent of Li, Y, Zr, and P was 100:1:1.2:6.1:3.8:50. The matrix was dried at 200℃ for 3 hours, then sintered at high temperature and calcined at 850℃ for 6 hours to form a NASICON-type (LYZP) coating on the surface of the ternary material matrix I. The coating structure is Li 1.3 Y 0.3 Zr 1.7 (PO4)3 yields a fast-charging high-voltage cathode material.

[0037] Compared with Example 1, Example 4 differs in that the mass ratio of matrix I to Li, Y, Zr and P compounds and ethanol solution in step (5) is changed from (100:1:1.2:6.1:3.8:50) to (100:0.5:0.6:3.0:1.9:50), while other conditions remain unchanged.

[0038] The difference between Comparative Example 1 (precursor without multi-element doping) and Example 1 is that the Al, Zr, Mg and Ti element additives in step (1) are removed, while other conditions remain unchanged.

[0039] The difference between Comparative Example 2 (precursor without cobalt-rich gradient design) and Example 1 is that the multi-stage preparation method of the precursor in step (1) is changed to a one-step method, the additive salt solution is added to the first material solution, and other conditions remain unchanged.

[0040] The difference between Comparative Example 3 and Example 1 is that the additive elements (Al, Zr, Mg, Ti and W, Nb, Y) in steps (1) and (2) are removed, while other conditions remain unchanged.

[0041] The difference between Comparative Example 4 and Example 1 is that the fast ion conductor material used in step (3) is removed and replaced with Al, Zr, W and Ti oxide coating, while other conditions remain unchanged.

[0042] In the experimental example, the above-mentioned fast-charging high-voltage positive electrode material, polyvinylidene fluoride (PVDF), N-methylpyrrolidone (NMP) and acetylene black were mixed evenly to prepare a positive electrode slurry. The negative electrode material, binder LA133 and carbon nanotubes (CNT) were mixed evenly to prepare a mixed negative electrode slurry. The positive and negative electrode slurries were then processed through coating-rolling-slicing-winding-assembly-liquid injection-formation-second sealing-capacity testing to prepare the finished soft-pack battery.

[0043] Electrochemical performance testing of pouch batteries: Test method for first charge specific capacity and first discharge specific capacity: Under 25℃ conditions, charge the pouch battery at 0.1C and discharge at 0.1C, with a voltage range of 3V-4.5V.

[0044] The capacity retention rate test method is as follows: At 45°C, the pouch battery is charged at 0.5C, and subjected to 500 cycles of 0.5C charge-discharge testing, with a voltage range of 3V-4.50V. The capacity retention rate in week X is calculated as (discharge specific capacity in week X / discharge specific capacity in week 1) × 100%, where X = 100, 200, 300, 400, or 500. The fast-charging rate performance test method is as follows: At 25°C, the pouch battery is charged at 0.1C, discharged at 0.1C, and then subjected to 0.5C charge / 0.5C discharge, 1C charge / 1C discharge, and 3C charge / 3C discharge. The retention rate at nC rate is calculated as nC discharge specific capacity / first cycle 0.1C discharge specific capacity. Table 1 shows the performance test results of the batteries prepared in the examples and comparative examples.

[0045] Table 2. Test results of charging rate performance of batteries prepared in the examples and comparative examples.

[0046] As shown in Tables 1 and 2 above, the capacity retention rate of each embodiment of the present invention after 500 cycles is greater than 90%, significantly improving the kinetic performance of lithium ions and thus enhancing the rate stability of the material. This not only effectively solves the problem of poor cycle performance of full batteries under ultra-high voltage, but also significantly improves the kinetic performance and fast-charging capability of the cathode material, significantly increasing the battery's energy density and fast-charging capability. Comparative Example 1 lacks doping elements, resulting in poor stability and poor fast-charging capability. Comparative Example 2 did not undergo cobalt gradient coating, resulting in a lower lithium-ion migration rate and insufficient lithium-ion kinetic performance, leading to poor battery performance. Comparative Example 3 lacks high-entropy doping, and its stability is further reduced compared to Comparative Example 1. Comparative Example 4 did not use the LYZP coating of the present invention, resulting in a lower lithium-ion diffusion rate and poor battery performance.

[0047] 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 fast-charging high-voltage positive electrode material, characterized in that, The process includes the following steps: Step 1: A first solution containing nickel ions, cobalt ions, and manganese ions is subjected to a co-precipitation reaction to obtain slurry I; the weight of cobalt in the first solution is 5%~10% of the total weight of nickel, cobalt, and manganese; Step 2: A second solution containing nickel salts, cobalt salts, and manganese salts is added to slurry I to undergo a co-precipitation reaction to obtain slurry II; the weight of cobalt in the second solution is 20%~28% of the total weight of nickel, cobalt, and manganese; Step 3: A third solution containing nickel salts, cobalt salts, and manganese salts is added to slurry II to undergo a co-precipitation reaction. The reaction yields slurry III, wherein the weight of cobalt in the third solution is 30%~35% of the total weight of nickel, cobalt, and manganese; after aging and drying the slurry III, a gradient cobalt-rich precursor is obtained; the first, second, and / or third solutions contain at least one of titanium ions, magnesium ions, zirconium ions, and magnesium ions; step four: the gradient cobalt-rich precursor, lithium source, and high-entropy doping source are mixed and then calcined to obtain a doped gradient cobalt-rich substrate; step five: a coating containing Li, Y, Zr, and P is coated on the surface of the doped gradient cobalt-rich substrate, and then calcined to obtain the fast-charging high-voltage cathode material.

2. The method for preparing the fast-charging high-voltage positive electrode material according to claim 1, characterized in that, In step one, the first liquid contains titanium ions, and the weight of titanium in the first liquid is 0.05%-0.10% of the total weight of nickel, cobalt, and manganese; in step two, the second liquid contains magnesium ions, and the weight of magnesium in the second liquid is 0.03%-0.06% of the total weight of nickel, cobalt, and manganese; in step three, the third liquid contains zirconium ions and aluminum ions, and the weight of zirconium in the third liquid is 0.2%-0.3% of the total weight of nickel, cobalt, and manganese, and the weight of aluminum is 0.1%-0.2% of the total weight of nickel, cobalt, and manganese.

3. The method for preparing the fast-charging high-voltage positive electrode material according to claim 1, characterized in that, When the first, second, and third solutions undergo co-precipitation, a complexing agent and a precipitant are added; the complexing agent is at least one of ammonia, ammonium bisulfate, and EDTA; the precipitant is at least one of sodium hydroxide and sodium carbonate.

4. The method for preparing the fast-charging high-voltage positive electrode material according to claim 1, characterized in that, In step four, the calcination is carried out in an oxygen atmosphere at a temperature of 900-960℃ for a holding time of 9-12 hours.

5. The method for preparing the fast-charging high-voltage positive electrode material according to claim 1, characterized in that, In step four, the molar ratio of lithium in the lithium source to nickel, cobalt, and manganese in the gradient cobalt-rich precursor is 1.04-1.07; the high-entropy doping source includes WO3, Nb2O5, and Y2O3; and the molar ratio of the high-entropy doping source to the lithium source is 0.3% to 0.5%.

6. The method for preparing the fast-charging high-voltage positive electrode material according to claim 1, characterized in that, In step five, the temperature is 800-900℃, and the holding time is 4-8 hours.

7. The method for preparing the fast-charging high-voltage positive electrode material according to claim 1, characterized in that, The method for coating the surface of the doped gradient cobalt-rich substrate with a coating containing Li, Y, Zr and P is as follows: the doped gradient cobalt-rich substrate is placed in a solution containing Li, Y, Zr and P, and then dried at 150~250℃ for 3-4 hours.

8. The method for preparing the fast-charging high-voltage positive electrode material according to claim 1, characterized in that, The molar ratio of Li:Y:Zr:P in the solution containing Li, Y, Zr and P is 1.2-1.4:0.2-0.4:1.5-2.0:2.5-3.

5.

9. The fast-charging high-voltage cathode material prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the fast-charging high-voltage cathode material of claim 9 in lithium batteries.

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