A high-nickel NCA composite cathode material, a preparation method and application thereof

Abstract

The application relates to the technical field of lithium ion batteries, in particular to a high-nickel NCA composite positive electrode material and a preparation method and application thereof. The application provides a preparation method of a high-nickel NCA composite positive electrode material, which comprises the following steps: mixing, stirring, first-step sintering and second-step sintering of a nickel-cobalt precursor, an aluminum source, a germanium source and a lithium source to obtain Ge-doped Li 1+a Ni x Co y Al z O2; mixing Ge-doped Li 1+ a Ni x Co y Al z O2 and a tungsten source, third-step sintering and fourth-step sintering to obtain the high-nickel NCA composite positive electrode material. The preparation of the positive electrode material is carried out through a four-step sintering process, and a tungsten source introduction reagent is reasonably optimized, so that germanium and tungsten respectively play a pinning effect in different windows, the formation of coarse Li2WO4 is avoided, the phenomenon of abnormal growth of primary grains is reduced, the length-diameter ratio of the primary grains is reduced, and therefore the capacity, rate performance and cycle stability of the battery are improved.

Description

Technical Field

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

[0002] High-nickel NCA (lithium nickel cobalt aluminum oxide) cathode materials have broad application prospects in electric vehicles, energy storage systems, and high-end consumer electronics due to their high specific capacity and good structural stability. This material achieves higher energy density by increasing the nickel content, but it also faces challenges in thermal stability and cycle life.

[0003] During the sintering process of NCA materials, the growth behavior of primary grains is often difficult to control precisely due to fluctuations and interactions in process parameters. This uncontrollability directly leads to a decrease in the consistency of the material's microstructure, specifically manifested as a widening of grain size distribution, a significant increase in aspect ratio, and the potential for excessive growth of localized abnormal grains. This severely restricts the full realization of the capacity, rate performance, and cycle stability of lithium-ion batteries. Summary of the Invention

[0004] The purpose of this invention is to solve the problem of uneven primary grain distribution in high-nickel NCA materials in the prior art, which leads to low battery capacity, rate performance and cycle stability, and to provide a high-nickel NCA composite cathode material, its preparation method and application.

[0005] This invention provides a method for preparing a high-nickel NCA composite cathode material, comprising the following steps: S1, mixing and stirring a nickel-cobalt precursor with an aluminum source, a germanium source, and a lithium source, followed by a first-step sintering and a second-step sintering to obtain Ge-doped Li. 1+ a Ni x Co y Al z O2; S2, Ge-doped Li 1+a Ni x Co y Al z O2 and tungsten source are mixed, and then sintered in the third and fourth steps to obtain the high-nickel NCA composite cathode material.

[0006] In some optional embodiments, the nickel-cobalt precursor has the chemical formula Ni x Co y (OH)2; where x≥0.8, 0.01≤y≤0.20, x+y=1.

[0007] In some alternative embodiments, the D50 of the nickel-cobalt precursor is 3 μm-15 μm.

[0008] In some alternative embodiments, the aluminum source includes at least one of Al(OH)3 or Al2O3.

[0009] In some alternative implementations, the germanium source includes GeO2.

[0010] In some alternative embodiments, the lithium source includes LiOH·H2O.

[0011] In some alternative embodiments, the D50 of the germanium source is 50nm-100nm.

[0012] In some alternative embodiments, the D50 of the lithium source is 4nm-10nm.

[0013] In some optional embodiments, the molar amount of aluminum in the aluminum source is in the ratio of the total molar amount of nickel, cobalt in the nickel-cobalt precursor and aluminum in the aluminum source to (0.01-0.05):1.

[0014] In some optional embodiments, the total molar amount of nickel and cobalt in the nickel-cobalt precursor and aluminum in the aluminum source, the molar ratio of germanium source and lithium source is 1:(0.03%-1%):(1.01-1.09).

[0015] In some optional embodiments, the mixing speed is 500 rpm to 2200 rpm; the mixing time is 40 min to 50 min.

[0016] In some optional embodiments, the heating rate of the first sintering step is 2℃ / min-5℃ / min; the temperature of the first sintering step is 350℃-550℃; and the holding time of the first sintering step is 4h-8h.

[0017] In some optional embodiments, the heating rate of the second sintering step is 1℃ / min-4℃ / min; the sintering temperature of the second step is 600℃-700℃; and the holding time of the second sintering step is 4h-14h.

[0018] In some alternative embodiments, the tungsten source includes WO3.

[0019] In some alternative embodiments, the D50 of the tungsten source is 50nm-100nm.

[0020] In some alternative embodiments, the molar amount of the tungsten source is related to the amount of Ge-doped Li. 1+a Ni x Co y Al z The ratio of the total molar amounts of Ni, Co, and Al in O2 is (0.1%~0.5%):1.

[0021] In some alternative embodiments, the molar ratio of the tungsten source to the germanium source is 1:(2-5).

[0022] In some optional embodiments, in step S2, the heating rate of the third sintering step is 0.5℃ / min-2℃ / min; the sintering temperature of the third step is 650℃-720℃; and the holding time of the third sintering step is 1h-4h.

[0023] In some optional embodiments, in step S2, the heating rate of the fourth sintering step is 1℃ / min-4℃ / min; the sintering temperature of the fourth step is 730℃-800℃; and the holding time of the fourth sintering step is 8h-16h.

[0024] Secondly, the present invention provides a high-nickel NCA composite cathode material, wherein the lithium-ion composite cathode is prepared by the preparation method described in the first aspect.

[0025] Thirdly, the present invention provides a lithium-ion battery, the lithium-ion battery comprising a high-nickel NCA composite cathode material prepared by the preparation method of the high-nickel NCA composite cathode material described in the first aspect or the high-nickel NCA composite cathode material described in the second aspect.

[0026] The technical solution of this invention has the following advantages: This invention provides a method for preparing a high-nickel NCA composite cathode material, comprising the following steps: S1, mixing and stirring a nickel-cobalt precursor with an aluminum source, a germanium source, and a lithium source, followed by a first-step sintering and a second-step sintering to obtain Ge-doped Li. 1+ a Ni x Co y Al z O2; S2, Ge-doped Li 1+a Ni x Co y Al z O2 and tungsten source are mixed, followed by a third and fourth sintering step to obtain the high-nickel NCA composite cathode material. The high-nickel NCA composite cathode material prepared by this invention utilizes a four-step sintering process and optimizes the introduction of the tungsten source reagent, allowing germanium and tungsten to exert pinning effects at different windows. This avoids the formation of coarse Li2WO4, reduces abnormal primary grain growth, and lowers the aspect ratio of the primary grains, thereby improving the capacity, rate performance, and cycle stability of batteries containing this high-nickel NCA composite cathode material.

[0027] Furthermore, the high-nickel NCA composite cathode material provided by this invention forms uniformly sized primary grains through co-doping with germanium and tungsten, giving the cathode material sufficient compaction density and reducing the problems of excessive specific surface area and aggravated side reactions caused by excessively small grains. At the same time, it reduces the aspect ratio of the primary grains, reducing the generation of cracks in the cathode sheet during rolling and cycling, thereby reducing electrolyte penetration and the occurrence of side reactions, and thus improving the rate performance and cycle stability of the battery. Attached Figure Description

[0028] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 Here is a SEM image of the cathode material prepared in Example 1 of this invention; Figure 2 Here is a SEM image of the cathode material prepared in Comparative Example 1 of this invention; Figure 3 Here is a SEM image of the cathode material prepared in Comparative Example 2 of this invention; Figure 4 This is a SEM image of the cathode material prepared in Comparative Example 3 of this invention; Figure 5 This is the XRD pattern of the cathode material prepared in Example 1 of the present invention. Detailed Implementation

[0030] 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.

[0031] 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.

[0032] Example 1 This embodiment provides a method for preparing a high-nickel NCA composite cathode material, including the following steps: (1) Ni with a D50 of 12 μm 0.92 Co 0.08Al(OH)2 with a D50 of 100 nm, LiOH·H2O with a D50 of 8 μm, and GeO2 with a D50 of 100 nm were mixed and stirred at 2000 rpm for 45 min. Under an oxygen atmosphere of 30 L / min, the temperature was first increased to 520 °C at a heating rate of 2 °C / min and held for 6 h. Then, the temperature was increased to 650 °C at a heating rate of 2 °C / min and held for 4 h to obtain a Ge-doped cathode material. Among them, Al accounts for 3% of the total molar amount of Ni, Co, and Al, the molar amount of GeO2 accounts for 0.8% of the total molar amount of Ni, Co, and Al, and the molar amount of LiOH·H2O to the total molar amount of Ni, Co, and Al is 1.03:1. (2) WO3 with a D50 of 100 nm was introduced into a sintering furnace at 650 °C using oxygen as the carrier gas and mixed with Ge-doped cathode material. Then, the temperature was increased to 680 °C at a rate of 2 °C / min and held for 3 h; then the temperature was increased to 760 °C at a rate of 2 °C / min and held for 10 h to obtain cathode material; wherein, the molar amount of WO3 accounted for 0.3% of the total molar amount of Ni, Co and Al. (3) The cathode material is crushed to a D50 of 12 μm, and then demagnetized and purified by a magnetic field with an intensity of 5000 Gauss to obtain the high-nickel NCA composite cathode material.

[0033] Example 2 This embodiment provides a method for preparing a high-nickel NCA composite cathode material, including the following steps: (1) Ni with a D50 of 12 μm 0.90 Co 0.10 Al(OH)2 with a D50 of 100 nm, LiOH·H2O with a D50 of 4 μm, and GeO2 with a D50 of 100 nm were mixed and stirred at 2000 rpm for 45 min. Under an oxygen atmosphere of 30 L / min, the temperature was first increased to 380 °C at a heating rate of 2 °C / min and held for 4 h. Then, the temperature was increased to 650 °C at a heating rate of 2 °C / min and held for 4 h to obtain a Ge-doped cathode material. Among them, Al accounted for 5% of the total molar amount of Ni, Co, and Al, the molar amount of GeO2 accounted for 0.8% of the total molar amount of Ni, Co, and Al, and the molar amount of LiOH·H2O was 1.02:1 compared with the total molar amount of Ni, Co, and Al. (2) WO3 with a D50 of 100 nm was introduced into a sintering furnace at 650 °C using oxygen as the carrier gas and mixed with Ge-doped cathode material. Then, the temperature was increased to 680 °C at a rate of 2 °C / min and held for 3 h; then the temperature was increased to 790 °C at a rate of 2 °C / min and held for 16 h to obtain cathode material; wherein, the molar amount of WO3 accounted for 0.3% of the total molar amount of Ni, Co and Al. (3) The cathode material is crushed to a D50 of 12 μm, and then demagnetized and purified by a magnetic field with an intensity of 5000 Gauss to obtain the high-nickel NCA composite cathode material.

[0034] Example 3 This embodiment provides a method for preparing a high-nickel NCA composite cathode material, including the following steps: (1) Ni with a D50 of 8 μm 0.92 Co 0.08 Al(OH)2 with a D50 of 200 nm, LiOH·H2O with a D50 of 10 μm, and GeO2 with a D50 of 100 nm were mixed and stirred at 2000 rpm for 45 min. Under an oxygen atmosphere of 30 L / min, the temperature was first increased to 520 °C at a heating rate of 5 °C / min and held for 6 h. Then, the temperature was increased to 700 °C at a heating rate of 4 °C / min and held for 3 h to obtain a Ge-doped cathode material. Among them, Al accounted for 3% of the total molar amount of Ni, Co, and Al, the molar amount of GeO2 accounted for 1.0% of the total molar amount of Ni, Co, and Al, and the molar ratio of LiOH·H2O to the total molar amount of Ni, Co, and Al was 1.03:1. (2) WO3 with a D50 of 100 nm was introduced into a sintering furnace at 700 °C using oxygen as the carrier gas and mixed with Ge-doped cathode material. Then, the temperature was increased to 720 °C at a rate of 2 °C / min and held for 3 h; then the temperature was increased to 760 °C at a rate of 2 °C / min and held for 10 h to obtain cathode material; wherein, the molar amount of WO3 accounted for 0.1% of the total molar amount of Ni, Co and Al. (3) The cathode material is crushed to a D50 of 8 μm, and then demagnetized and purified by a magnetic field with an intensity of 5000 Gauss to obtain the high-nickel NCA composite cathode material.

[0035] Comparative Example 1 This comparative example provides a method for preparing a cathode material, including the following steps: (1) Ni with a D50 of 12 μm 0.92 Co 0.08 Al(OH)2 and Al(OH)3 with a D50 of 100 nm and LiOH·H2O were mixed and stirred at 2000 rpm for 45 min. Under an oxygen atmosphere of 30 L / min, the temperature was first increased to 520 °C at a heating rate of 2 °C / min and held for 6 h. Then, the temperature was increased to 650 °C at a heating rate of 2 °C / min and held for 4 h to obtain a ternary cathode material. In this material, Al accounts for 3% of the total molar amount of Ni, Co and Al, and the molar amount of LiOH·H2O is 1.03:1 to the total molar amount of Ni, Co and Al. (2) In an oxygen flow of 30 L / min, the ternary cathode material was first heated to 680 °C at a rate of 2 °C / min and held for 3 h; then heated to 760 °C at a rate of 2 °C / min and held for 10 h. After cooling to room temperature, it was pulverized to a D50 of 12 μm and then demagnetized and purified by a magnetic field of 5000 Gauss to obtain the cathode material. Comparative Example 2 This comparative example provides a method for preparing a high-nickel NCA composite cathode material, including the following steps: (1) Ni with a D50 of 12 μm 0.92 Co 0.08 Al(OH)2 and Al(OH)3 with a D50 of 100 nm and LiOH·H2O were mixed and stirred at 2000 rpm for 45 min. Under an oxygen atmosphere of 30 L / min, the temperature was first increased to 520 °C at a heating rate of 2 °C / min and held for 6 h. Then, the temperature was increased to 650 °C at a heating rate of 2 °C / min and held for 4 h to obtain a ternary cathode material. Among them, Al accounts for 3% of the total molar amount of Ni, Co and Al, and the molar amount of LiOH·H2O to the total molar amount of Ni, Co and Al is 1.02:1. (2) WO3 with a D50 of 100 nm was introduced into a sintering furnace at 650 °C using oxygen as the carrier gas and mixed with Ge-doped cathode material. Then, the temperature was increased to 680 °C at a rate of 2 °C / min and held for 3 h; then, the temperature was increased to 760 °C at a rate of 2 °C / min and held for 10 h; finally, the temperature was cooled to room temperature at a rate of 8 °C / min to obtain cathode material; wherein, the molar amount of WO3 accounted for 0.3% of the total molar amount of Ni, Co and Al. (3) The cathode material is crushed to a D50 of 12 μm, and then demagnetized and purified by a magnetic field with an intensity of 5000 Gauss to obtain the high-nickel NCA composite cathode material.

[0036] Comparative Example 3 This comparative example provides a method for preparing a high-nickel NCA composite cathode material, including the following steps: (1) Ni with a D50 of 12 μm 0.92 Co 0.08Al(OH)2, Al(OH)3 with a D50 of 100 nm, LiOH·H2O, and GeO2 with a D50 of 100 nm were mixed and stirred at 2000 rpm for 45 min. Under an oxygen atmosphere of 30 L / min, the temperature was first increased to 520 °C at a heating rate of 2 °C / min and held for 6 h. Then, the temperature was increased to 650 °C at a heating rate of 2 °C / min and held for 4 h to obtain a Ge-doped cathode material. Among them, Al accounts for 3% of the total molar amount of Ni, Co, and Al, the molar amount of GeO2 accounts for 0.8% of the total molar amount of Ni, Co, and Al, and the molar amount of LiOH·H2O is 1.03:1 to the total molar amount of Ni, Co, and Al. (2) In an oxygen flow of 30 L / min, the Ge-doped cathode material is first heated to 680 °C at a rate of 2 °C / min and held for 3 h; then heated to 760 °C at a rate of 2 °C / min and held for 10 h; finally cooled to room temperature at a rate of 8 °C / min to obtain the cathode material.

[0037] Comparative Example 4 This comparative example provides a method for preparing a high-nickel NCA composite cathode material, including the following steps: (1) Ni with a D50 of 12 μm 0.92 Co 0.08 Al(OH)2 with a D50 of 100 nm, LiOH·H2O with a D50 of 8 μm, GeO2 with a D50 of 100 nm, and WO3 with a D50 of 100 nm were mixed and stirred at 2000 rpm for 45 min. Under an oxygen atmosphere of 30 L / min, the temperature was first increased to 520 °C at a heating rate of 2 °C / min and held for 6 h. Then, the temperature was increased to 650 °C at a heating rate of 2 °C / min and held for 4 h to obtain a Ge and W co-doped cathode material. Among them, Al accounts for 3% of the total molar amount of Ni, Co, and Al, GeO2 accounts for 0.8% of the total molar amount of Ni, Co, and Al, the molar ratio of LiOH·H2O to the total molar amount of Ni, Co, and Al is 1.03:1, and WO3 accounts for 0.3% of the total molar amount of Ni, Co, and Al. (2) The Ge and W co-doped cathode material was heated to 680℃ at a rate of 2℃ / min and held for 3h; then heated to 760℃ at a rate of 2℃ / min and held for 10h to obtain the cathode material. (3) The cathode material is crushed to a D50 of 12 μm, and then demagnetized and purified by a magnetic field with an intensity of 5000 Gauss to obtain the high-nickel NCA composite cathode material.

[0038] Test case Characterization of cathode materials The surface residual alkali content of the cathode materials prepared in Example 1 and Comparative Examples 1-4 was determined by acid-base titration, and the test results are shown in Table 1.

[0039] Aspect ratio: The aspect ratio is the ratio of the longest side length to the shortest width of a particle obtained by scanning electron microscopy (SEM) images of 100 randomly selected particles. The results are shown in Table 1.

[0040] The peak heights of 003 and 104 were read from the XRD plot, and their ratio was calculated. The calculation results are shown in Table 1.

[0041] Table 1

[0042] From Table 1 and Figure 1-5 It is known that the high-nickel NCA composite cathode material prepared by the preparation method provided by the present invention, through Ge and W co-doping and combined with the staged sintering process, enables Ge and W to exert pinning effects at different temperature windows during the sintering process, resulting in a significant narrowing of the primary grain size distribution and a significant reduction in the aspect ratio. This indicates that through the four-step sintering process and the optimization of the timing of tungsten source introduction, the grain boundary pinning network formed by Ge and W effectively suppresses anisotropic growth and abnormal grain growth.

[0043] Electrochemical performance testing The high-nickel NCA composite cathode materials prepared in Examples 1-3 and Comparative Examples 1-4 were mixed with conductive carbon black and PVDF at a mass ratio of 92:4:4, respectively. NMP was used as a solvent to prepare a slurry, which was coated onto aluminum foil. After drying and rolling, the cathode sheet was formed. The lithium metal sheet was used as the anode, a single-layer polypropylene (Celgard 2400) was used as the separator, and a 1 mol / L LiPF6 EC / DMC / EMC (volume ratio 1:1:1) solution was used as the electrolyte. CR2032 coin cells were assembled in an argon glove box, and the performance was tested using the Xinwei Battery Testing System. The test results are shown in Table 2.

[0044] The test method for first-efficiency is as follows: Under constant temperature conditions of 25℃, charge the battery at 0.2C to 4.3V, then fully charge it at a constant voltage of 4.3V, and discharge it at 0.2C to 2.5V once. The formula for calculating first-efficiency is as follows: First-time efficiency = First discharge specific capacity / First charge specific capacity × 100%.

[0045] The cycle performance test method is as follows: the temperature is 25℃, the charging cut-off voltage is 4.3V, the discharging cut-off voltage is 2.5V, the battery is activated at 0.2C / 0.2C (cycle 1) → 0.2C / 0.2C (cycle 2) → 0.2C / 0.2C (cycle 3), and then the cycle is continued at 1C / 1C (cycle 4). The discharge capacity retention rate is calculated after 50 cycles and 200 cycles respectively.

[0046] 50-cycle retention rate = (53rd cycle discharge specific capacity / 4th cycle discharge specific capacity) × 100%; 200-cycle retention rate = discharge specific capacity at the 203rd cycle / discharge specific capacity at the 4th cycle × 100%.

[0047] Table 2. Performance test results of coin cells in each embodiment and comparative example.

[0048] As shown in Table 2, when the high-nickel NCA composite cathode material prepared by the method provided in this invention is applied to lithium-ion batteries, its initial efficiency is in the range of 91.4% to 91.8%, which is higher than that of Comparative Example 4 (89.4%). The discharge capacity at 0.2C rate is 216.7 mAh / g to 221.5 mAh / g, which is higher than that of Comparative Example 4 (211.2 mAh / g). The discharge capacity at 1C rate is 201.6 mAh / g to 207.7 mAh / g, which is higher than that of Comparative Example 4 (196.5 mAh / g). The capacity retention rate after 50 cycles is 96.9% to 97.9%, which is higher than that of Comparative Example 4 (93.3%). The capacity retention rate after 200 cycles is 91.7% to 92.1%, which is higher than that of Comparative Example 4 (89.7%). This indicates that by optimizing the timing of tungsten source introduction, the capacity, rate performance, and cycle life of the lithium-ion battery are effectively improved. Meanwhile, compared with Comparative Examples 1, 2 and 3, the battery prepared by the high-nickel NCA composite cathode material in Example 1 has better performance, indicating that the performance of NCA ternary cathode material is significantly improved by the synergistic effect of germanium and tungsten, thereby improving the capacity, rate performance and cycle life of lithium-ion batteries.

[0049] 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 high-nickel NCA composite cathode material, characterized in that: Includes the following steps: S1. Nickel-cobalt precursors are mixed and stirred with aluminum, germanium, and lithium sources, followed by a first sintering step and a second sintering step to obtain Ge-doped Li. 1+a Ni x Co y Al z O2; S2, Ge-doped Li 1+a Ni x Co y Al z O2 and tungsten source are mixed, and then sintered in the third and fourth steps to obtain the high-nickel NCA composite cathode material.

2. The method for preparing the high-nickel NCA composite cathode material according to claim 1, characterized in that, The chemical formula of the nickel-cobalt precursor is Ni x Co y (OH)2; where x≥0.8, 0.01≤y≤0.20, x+y=1; Preferably, the D50 of the nickel-cobalt precursor is 3μm-15μm.

3. The method for preparing the high-nickel NCA composite cathode material according to claim 2, characterized in that, The aluminum source includes at least one of Al(OH)3 or Al2O3; Preferably, the germanium source includes GeO2; Preferably, the lithium source includes LiOH·H2O.

4. The method for preparing the high-nickel NCA composite cathode material according to claim 3, characterized in that, The D50 of the aluminum source is 50nm-500nm; Preferably, the D50 of the germanium source is 50nm-100nm; Preferably, the D50 of the lithium source is 3μm-8μm.

5. The method for preparing the high-nickel NCA composite cathode material according to claim 4, characterized in that, The molar ratio of aluminum in the aluminum source to the total molar ratio of nickel, cobalt in the nickel-cobalt precursor and aluminum in the aluminum source is (0.01-0.05):1; Preferably, the total molar amounts of nickel and cobalt in the nickel-cobalt precursor and aluminum in the aluminum source, as well as the molar ratios of the germanium source and the lithium source, are 1:(0.03%-1%):(1.01-1.09). Preferably, the mixing speed is 500 rpm to 2200 rpm; the mixing time is 40 min to 50 min.

6. The method for preparing the high-nickel NCA composite cathode material according to claim 5, characterized in that, The heating rate of the first sintering step is 2℃ / min-5℃ / min; the sintering temperature of the first step is 350℃-550℃; and the holding time of the first sintering step is 4h-8h. Preferably, the heating rate of the second sintering step is 1℃ / min-4℃ / min; the sintering temperature of the second step is 600℃-700℃; and the holding time of the second sintering step is 6h-14h.

7. The method for preparing the high-nickel NCA composite cathode material according to claim 6, characterized in that, The tungsten source includes WO3; Preferably, the D50 of the tungsten source is 30nm-50nm; Preferably, the molar amount of the tungsten source is similar to that of the Ge-doped Li. 1+a Ni x Co y Al z The total molar ratio of Ni, Co, and Al in O2 is (0.1%~0.5%): 1; Preferably, the molar ratio of the tungsten source to the germanium source is 1:(2-5).

8. The method for preparing the high-nickel NCA composite cathode material according to claim 7, characterized in that, In step S2, the heating rate of the third sintering step is 0.5℃ / min-2℃ / min; the sintering temperature of the third step is 650℃-750℃; and the holding time of the third sintering step is 1h-6h. Preferably, in step S2, the heating rate of the fourth sintering step is 1℃ / min-4℃ / min; the sintering temperature of the fourth step is 730℃-800℃; and the holding time of the fourth sintering step is 8h-16h.

9. A high-nickel NCA composite cathode material, characterized in that, The high-nickel NCA composite cathode material is prepared by the preparation method of the high-nickel NCA composite cathode material according to any one of claims 1-8.

10. A lithium-ion battery, characterized in that, The lithium-ion battery includes the high-nickel NCA composite cathode material prepared by the preparation method of the high-nickel NCA composite cathode material according to any one of claims 1-8, or the high-nickel NCA composite cathode material according to claim 9.

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