Coated modified nickel-based positive electrode material and preparation method thereof, lithium ion battery and electric device

Abstract

The invention discloses a coated modified nickel-based positive electrode material. The coated modified nickel-based positive electrode material comprises a nickel-based positive electrode material matrix and a perovskite type composite oxide coating layer ABbGa1-bO3 <->, wherein the surface of the nickel-based positive electrode material matrix is coated with the perovskite type composite oxide coating layer ABbGa1-bO3 <->. The preparation method comprises the following steps: uniformly mixing a nickel-cobalt-manganese hydroxide precursor and a lithium source, and sintering; washing and drying the sintered product; and mixing the washed product with a gallium source, an A-element-containing compound and a B-element-containing compound, and sintering to obtain the coated modified nickel-based positive electrode material. The invention also discloses a lithium ion battery containing the coated modified nickel-based positive electrode material and an electric device. According to the invention, the surface of the nickel-based positive electrode material substrate is coated with the perovskite type composite oxide coating layer, so that the high-voltage cycle stability and rate capability of the positive electrode material can be improved, and the coated modified nickel-based positive electrode material has good thermal stability and chemical stability.

Description

Technical Field

[0001] This invention belongs to the field of battery materials, and particularly relates to a coated modified nickel-based cathode material and its preparation method, lithium-ion batteries, and electrical devices. Background Technology

[0002] In recent years, with the development of the new energy industry, lithium-ion batteries have been widely used in consumer electronics, electric vehicles, and energy storage. High-capacity, high-voltage, and low-cost nickel-rich cathode materials are the most promising alternatives to traditional lithium cobalt oxide cathode materials. However, due to their high nickel content, nickel-rich cathode materials suffer from poor cycle performance and safety performance, which require further improvement.

[0003] Currently, the traditional production process for high-nickel ternary cathode materials employs a water washing process. However, because high-nickel ternary cathode materials are sensitive to moisture, excessive washing can lead to lithium deposition on the material matrix surface, damaging the surface structure. Furthermore, due to the high nickel content of high-nickel ternary cathode materials, side reactions with the electrolyte are severe during charge and discharge, resulting in high surface impedance and poor cycle performance. Existing technologies employ modification methods such as dry sintering and coating to address these issues, but the modification effects remain unsatisfactory. Problems such as surface side reactions and rapid impedance growth persist, affecting the electrochemical performance of nickel-rich cathode materials. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the background art above, and to provide a coated modified nickel-based cathode material and its preparation method, a lithium-ion battery and an electrical device.

[0005] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows: A modified nickel-based cathode material includes a nickel-based cathode material matrix and an ABO3 perovskite-type composite oxide coating layer coated on the surface of the nickel-based cathode material matrix. The chemical formula of the ABO3 perovskite-type composite oxide coating layer is AB. b Ga 1-b O 3-δ Where δ is the oxygen vacancy value, 0≤δ≤0.5, b≤0.8, the ionic radius of element A is ≥0.80Å, and the ionic radius of element B is ≤0.70Å.

[0006] In the above-mentioned coated modified nickel-based cathode material, preferably, element A includes at least one of Na, K, La, Y, Sr, Ca, Ba, Gd, Sm, Eu, Dy or Nd, and element B includes at least one of Fe, Co, Ni, Mn, Al or Ti.

[0007] In the above-mentioned coated modified nickel-based cathode material, preferably, the molar ratio of element A to element Ga in the ABO3 perovskite composite oxide coating layer is (0.9~1.0):(0.2~1.0).

[0008] In the above-mentioned coated modified nickel-based cathode material, preferably, the thickness of the ABO3 perovskite composite oxide coating layer is 2nm-50nm, and the mass of the ABO3 perovskite composite oxide coating layer accounts for 0.1%-1% of the mass of the nickel-based cathode material matrix.

[0009] Preferably, in the above-mentioned coated modified nickel-based cathode material, the chemical formula of the nickel-based cathode material matrix is ​​Li. z Ni 1-x-y Co x M y O2, wherein element M includes one or more of Mn or Al, 0.9≤z≤1.1, 0≤x≤0.2, 0≤y≤0.2.

[0010] Preferably, the aforementioned coated modified nickel-based cathode material has a compaction density of 3.1-3.2 g / cm³ at a pressure of 99 MPa. 3 Under these conditions, its powder conductivity is not less than 0.04 S / cm; The modified nickel-based cathode material, as tested by DSC, has a peak temperature of not less than 210℃.

[0011] Based on a general inventive concept, the present invention also provides a method for preparing the above-described coated modified nickel-based cathode material, comprising the following steps: (1) The nickel cobalt manganese hydroxide precursor and the lithium source were mixed evenly and then sintered to obtain the sintered product; (2) The sintered product obtained in step (1) is washed with water and dried to obtain the washed product; (3) The water-washed product obtained in step (2) is mixed with gallium source, A-containing compound and B-containing compound, and then sintered to obtain the coated modified nickel-based cathode material.

[0012] In the above preparation method, preferably, in step (1), the lithium source is one or more of lithium hydroxide, lithium carbonate or lithium nitrate; the sintering treatment includes two-stage sintering, first heating to 400-600℃ and holding for 2-5h, then heating to 700-800℃ and holding for 8-20h.

[0013] In the above preparation method, preferably, in step (2), the water washing temperature is 5-25℃, the solid-liquid mass ratio during the water washing process is 1.0-3.0, the water washing time is 2-5 min, and the stirring speed is 400-900 rpm.

[0014] In the above preparation method, preferably, in step (3), the gallium source is one or more of gallium trioxide, gallium trisulfide, and gallium hydroxide, the A-containing compound is one or more of oxides, hydroxides, chlorides, carbonates, or nitrates containing element A, and the B-containing compound is one or more of oxides, hydroxides, chlorides, carbonates, or nitrates containing element B.

[0015] In the above preparation method, preferably, in step (3), the sintering treatment includes two sintering stages: first, heating to 100-300℃ and holding for 1-5 hours, then heating to 500-700℃ and holding for 4-12 hours.

[0016] Based on a general inventive concept, the present invention also provides a lithium-ion battery comprising the above-described coated modified nickel-based cathode material or the coated modified nickel-based cathode material prepared by the above-described preparation method.

[0017] Based on a general inventive concept, the present invention also provides an electrical device including the aforementioned lithium-ion battery.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention coats a perovskite-type composite oxide coating layer AB on the surface of a nickel-based cathode material substrate. b Ga 1- b O 3-δ Perovskite-type composite oxide coating layer AB b Ga 1-b O 3-δ The Ga element in the coating can inhibit the migration of Ni ions on the substrate surface, stabilize the TM-O bond, maintain the stability of the transition metal-oxygen bond under deep charge, and improve the high-voltage cycle stability and rate performance of the cathode material. In addition, the octahedral coordination of Ga and O in the coating structure has an ultra-wide bandwidth (4.2~4.9eV), is structurally stable, is not easily chemically corroded, and can stabilize HF in the electrolyte by-reaction products, protecting the cathode material substrate and exhibiting good thermal and chemical stability.

[0019] (2) The perovskite-type composite oxide coating layer AB in this invention b Ga 1-b O 3-δ A lithium-ion transport channel was established, which can significantly improve the lithium-ion diffusion rate. The coating layer has a high energy barrier, which can stabilize lattice oxygen, inhibit the evolution of active oxygen in the matrix, reduce oxygen loss, and at the same time provide active oxygen to repair surface Li / O defects generated in high-nickel materials during water washing or charge-discharge processes, reduce the internal resistance of the material, and has high ionic conductivity and electronic conductivity.

[0020] (3) In this invention, the perovskite structure of the coating layer matches the crystal structure of the matrix material. The coating layer forms stable chemical bonds on the surface of the matrix material, which is conducive to the formation of strong interfacial interactions and exhibits good lattice compatibility. During deep charging, it enhances the interfacial interaction between the bulk material and the surface coating layer. At the same time, it can utilize the anisotropy of the nickel-based cathode material lattice and the internal stress caused by contraction and expansion to trigger the piezoelectric effect of the Ga-based perovskite structure, forming a reverse intercalation electric field. This effectively suppresses the outward migration of lattice oxygen anions, thereby eliminating interfacial strain and effectively suppressing oxygen evolution in the lattice during high-voltage cycling. While increasing the lithium-ion diffusion rate, it also suppresses the lattice distortion caused by lithium-ion deintercalation and stabilizes the crystal structure of the material. The overall structure of the coating layer is stable, protecting the material surface, suppressing side reactions with the electrolyte, reducing the generation of nickel oxide phase on the surface of high-nickel materials during cycling, and greatly improving the cycling stability of the material.

[0021] (4) The preparation method of the present invention adopts the traditional dry sintering coating process, which is simple and can be applied on a large scale. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the 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 based on these drawings without creative effort.

[0023] Figure 1 This is a SEM image of the nickel-based cathode material prepared in Example 1 of the present invention. Detailed Implementation

[0024] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0025] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0026] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0027] Example 1: A coated modified nickel-based cathode material of the present invention includes a nickel-based cathode material matrix Li. 1.00 Ni0.93 Co 0.03 Mn 0.04 O2 and a perovskite-type composite oxide coating layer LaGa on the surface of the nickel-based cathode material matrix. 0.5 Co 0.5 The O3 coating layer has a mass of 0.72 wt% of the nickel-based cathode material matrix. The modified nickel-based cathode material is coated at a pressure of 99 MPa and a compaction density of 3.1 g / cm³. 3 The powder conductivity under the specified conditions is 0.067 S / cm.

[0028] The preparation method of the coated modified nickel-based cathode material in this embodiment includes the following steps: (1) Ni cobalt manganese hydroxide precursor Ni 0.93 Co 0.03 Mn 0.04 (OH)2 and lithium hydroxide monohydrate were added to a high-speed mixer at a molar ratio of 1:1.05 and stirred at 1800 rpm for 30 min. Then, in a box furnace with an oxygen concentration ≥96%, the temperature was increased to 500℃ at a heating rate of 3℃ / min and held for 2 h. The temperature was then increased to 740℃ and held for 12 h. The mixture was then allowed to cool naturally to room temperature, pulverized, and passed through a 300-mesh sieve to obtain the primary sintered material.

[0029] (2) Wash the sintered material obtained in step (1) with deionized water for 3 min. The solid-liquid mass ratio of the washing is 1.0. The temperature of the deionized water used for washing is controlled at 8℃. The stirring speed is 700 rpm. After washing, the sample is placed in a vacuum oven and vacuum dried at 160℃ for 6 h. Then it is naturally cooled to room temperature and passed through a 300-mesh sieve to obtain the washed product.

[0030] (3) The water-washed product, La2O3, Ga2O3, and Co(OH)2 were added to a high-speed mixer in a molar ratio of 1:0.00144:0.00072:0.00145. The mixture was stirred at 1800 rpm for 30 min. Then, in a box furnace under an oxygen atmosphere, the temperature was increased to 200℃ at a rate of 3℃ / min and held for 2 h. The temperature was then increased to 670℃ and held for 8 h. The mixture was then allowed to cool naturally to room temperature and sieved through a 300-mesh sieve to obtain the coated modified nickel-based cathode material. Its electron micrograph is shown in the figure. Figure 1 As shown.

[0031] Example 2: A coated modified nickel-based cathode material of the present invention includes a nickel-based cathode material matrix Li. 1.00 Ni 0.93 Co 0.03 Mn 0.04 O2 and a perovskite-type composite oxide coating layer CaGa on the surface of the nickel-based cathode material matrix.0.29 Co 0.71 The O3 coating layer has a mass of 0.37 wt% of the nickel-based cathode material matrix. The modified nickel-based cathode material is coated at a pressure of 99 MPa and a compaction density of 3.1 g / cm³. 3 The powder conductivity under the specified conditions is 0.079 S / cm.

[0032] The preparation method of the coated modified nickel-based cathode material in this embodiment includes the following steps: (1) Ni cobalt manganese hydroxide precursor Ni 0.93 Co 0.03 Mn 0.04 (OH)2 and lithium hydroxide monohydrate were added to a high-speed mixer at a molar ratio of 1:1.05 and stirred at 1800 rpm for 30 min. Then, in a box furnace with an oxygen concentration ≥96%, the temperature was increased to 500℃ at a heating rate of 3℃ / min and held for 2 h. The temperature was then increased to 740℃ and held for 12 h. The mixture was then allowed to cool naturally to room temperature, pulverized, and passed through a 300-mesh sieve to obtain the primary sintered material.

[0033] (2) Wash the sintered material obtained in step (1) with deionized water for 3 min. The solid-liquid mass ratio of the washing is 1.0. The temperature of the deionized water used for washing is controlled at 8℃. The stirring speed is 700 rpm. After washing, the sample is placed in a vacuum oven and vacuum dried at 160℃ for 6 h. Then it is naturally cooled to room temperature and passed through a 300-mesh sieve to obtain the washed product.

[0034] (3) The water-washed product, CaCO3, Ga2O3 and Co(OH)2 were added to a high-speed mixer in a molar ratio of 1:0.0025:0.00036:0.00178. The mixture was stirred at 1800 rpm for 30 min. Then, in a box furnace under an oxygen atmosphere, the temperature was raised to 200℃ at a heating rate of 3℃ / min and held for 2 h. The temperature was then raised to 670℃ and held for 8 h. The mixture was then naturally cooled to room temperature and sieved through a 300-mesh sieve to obtain the coated modified nickel-based cathode material.

[0035] Example 3: A coated modified nickel-based cathode material of the present invention includes a nickel-based cathode material matrix Li. 1.00 Ni 0.93 Co 0.03 Mn 0.04 O2 and the perovskite-type composite oxide coating layer EuGa on the surface of the nickel-based cathode material matrix. 0.82 Mn 0.18 The O3 coating layer has a mass of 0.70 wt% of the nickel-based cathode material matrix. The modified nickel-based cathode material is coated at a pressure of 99 MPa and a compaction density of 3.1 g / cm³. 3The powder conductivity under the specified conditions is 0.054 S / cm.

[0036] The preparation method of the coated modified nickel-based cathode material in this embodiment includes the following steps: (1) Ni cobalt manganese hydroxide precursor Ni 0.93 Co 0.03 Mn 0.04 (OH)2 and lithium hydroxide monohydrate were added to a high-speed mixer at a molar ratio of 1:1.05 and stirred at 1800 rpm for 30 min. Then, in a box furnace with an oxygen concentration ≥96%, the temperature was increased to 500℃ at a heating rate of 3℃ / min and held for 2 h. The temperature was then increased to 740℃ and held for 12 h. The mixture was then allowed to cool naturally to room temperature, pulverized, and passed through a 300-mesh sieve to obtain the primary sintered material.

[0037] (2) Wash the sintered material obtained in step (1) with deionized water for 3 min. The solid-liquid mass ratio of the washing is 1.0. The temperature of the deionized water used for washing is controlled at 8℃. The stirring speed is 700 rpm. After washing, the sample is placed in a vacuum oven and vacuum dried at 160℃ for 6 h. Then it is naturally cooled to room temperature and passed through a 300-mesh sieve to obtain the washed product.

[0038] (3) The water-washed product, Eu2O3, Ga2O3 and Mn(OH)2 were added to a high-speed mixer in a molar ratio of 1:0.00132:0.00108:0.00048. The mixture was stirred at 1800 rpm for 30 min. Then, in a box furnace under an oxygen atmosphere, the temperature was raised to 200℃ at a heating rate of 3℃ / min and held for 2 h. The temperature was then raised to 620℃ and held for 8 h. The mixture was then naturally cooled to room temperature and sieved through a 300-mesh sieve to obtain the coated modified nickel-based cathode material.

[0039] Comparative Example 1: The nickel-based cathode material in this comparative example is Li. 1.00 Ni 0.93 Co 0.03 Mn 0.04 O2, the preparation methods of which include: (1) Ni cobalt manganese hydroxide precursor Ni 0.93 Co 0.03 Mn 0.04 (OH)2 and lithium hydroxide monohydrate were added to a high-speed mixer at a molar ratio of 1:1.05 and stirred at 1800 rpm for 30 min. Then, in a box furnace with an oxygen concentration ≥96%, the temperature was increased to 500℃ at a heating rate of 3℃ / min and held for 2 h. The temperature was then increased to 740℃ and held for 12 h. The mixture was then allowed to cool naturally to room temperature, pulverized, and passed through a 300-mesh sieve to obtain the primary sintered material.

[0040] (2) Wash the sintered material obtained in step (1) with deionized water for 3 min. The solid-liquid mass ratio of the washing is 1.0. The temperature of the deionized water used for washing is controlled at 8℃. The stirring speed is 700 rpm. After washing, the sample is placed in a vacuum oven and vacuum dried at 160℃ for 6 h. Then it is naturally cooled to room temperature and passed through a 300-mesh sieve to obtain the washed product.

[0041] (3) The water-washed product was heated to 200°C in a box furnace under an oxygen atmosphere at a heating rate of 3°C / min and held for 2 hours. Then it was heated to 670°C and held for 8 hours. After cooling naturally to room temperature, it was sieved through a 300-mesh sieve to obtain nickel-based cathode material.

[0042] Comparative Example 2: The modified nickel-based cathode material in this comparative example includes Li 1.00 Ni 0.93 Co 0.03 Mn 0.04 An O2 matrix, with a Ga2O3 layer coated on its surface, is prepared by the following methods: (1) Ni cobalt manganese hydroxide precursor Ni 0.93 Co 0.03 Mn 0.04 (OH)2 and lithium hydroxide monohydrate were added to a high-speed mixer at a molar ratio of 1:1.05 and stirred at 1800 rpm for 30 min. Then, in a box furnace with an oxygen concentration ≥96%, the temperature was increased to 500℃ at a heating rate of 3℃ / min and held for 2 h. The temperature was then increased to 740℃ and held for 12 h. The mixture was then allowed to cool naturally to room temperature, pulverized, and passed through a 300-mesh sieve to obtain the primary sintered material.

[0043] (2) Wash the sintered material obtained in step (1) with deionized water for 3 min. The solid-liquid mass ratio of the washing is 1.0. The temperature of the deionized water used for washing is controlled at 8℃. The stirring speed is 700 rpm. After washing, the sample is placed in a vacuum oven and vacuum dried at 160℃ for 6 h. Then it is naturally cooled to room temperature and passed through a 300-mesh sieve to obtain the washed product.

[0044] (3) The water-washed product and Ga2O3 were added to a high-speed mixer at a molar ratio of 1:0.00072 and stirred at 1800 rpm for 30 min. Then, in a box furnace under an oxygen atmosphere, the temperature was raised to 200℃ at a heating rate of 3℃ / min and held for 2 h. The temperature was then raised to 670℃ and held for 8 h. The mixture was naturally cooled to room temperature and sieved through a 300-mesh sieve to obtain the nickel-based cathode material.

[0045] Comparative Example 3: The modified nickel-based cathode material in this comparative example includes Li 1.00 Ni 0.93 Co0.03 Mn 0.04 The O2 matrix, with a LaCoO3 layer coated on its surface, is prepared by the following methods: (1) Ni cobalt manganese hydroxide precursor Ni 0.93 Co 0.03 Mn 0.04 (OH)2 and lithium hydroxide monohydrate were added to a high-speed mixer at a molar ratio of 1:1.05 and stirred at 1800 rpm for 30 min. Then, in a box furnace with an oxygen concentration ≥96%, the temperature was increased to 500℃ at a heating rate of 3℃ / min and held for 2 h. The temperature was then increased to 740℃ and held for 12 h. The mixture was then allowed to cool naturally to room temperature, pulverized, and passed through a 300-mesh sieve to obtain the primary sintered material.

[0046] (2) Wash the sintered material obtained in step (1) with deionized water for 3 min. The solid-liquid mass ratio of the washing is 1.0. The temperature of the deionized water used for washing is controlled at 8℃. The stirring speed is 700 rpm. After washing, the sample is placed in a vacuum oven and vacuum dried at 160℃ for 6 h. Then it is naturally cooled to room temperature and passed through a 300-mesh sieve to obtain the washed product.

[0047] (3) The water-washed product, La2O3, and Co(OH)2 were added to a high-speed mixer in a molar ratio of 1:0.00144:0.0029 and stirred at 1800 rpm for 30 min. Then, in a box furnace under an oxygen atmosphere, the temperature was raised to 200℃ at a heating rate of 3℃ / min and held for 2 h. The temperature was then raised to 670℃ and held for 8 h. The mixture was then naturally cooled to room temperature and sieved through a 300-mesh sieve to obtain the modified nickel-based cathode material.

[0048] Performance testing: The electrochemical performance of the nickel-based cathode materials in the above examples and comparative examples was studied using CR2032 coin cells.

[0049] Positive electrode sheet: The positive electrode materials of Examples 1-3 and Comparative Examples 1-3 were stirred and dispersed with conductive carbon black (SP) and polyvinylidene fluoride (PVDF) in a mass ratio of 92.5:5:2.5 with solvent NMP, coated on aluminum foil substrate, and rolled to obtain positive electrode sheet.

[0050] Negative electrode: Lithium metal sheet.

[0051] Electrolyte: 1 mol / L LiPF6 solution, with EC and DMC as a mixed solvent in a ratio of 1:2, and 1% VC as an additive.

[0052] The CR2032 button cell was assembled and tested. The charging cutoff voltage was 4.3V and the discharging cutoff voltage was 3.0V.

[0053] The following are the test results of the electrical properties of the cathode materials prepared in Examples 1-3 and Comparative Examples 1-3, as shown in Table 1.

[0054] Table 1: Electrical performance test results of nickel-based cathode materials in Examples 1-3 and Comparative Examples 1-3

[0055] As shown in Table 1, the coated and modified nickel-based cathode materials in Examples 1-3 significantly improve the initial discharge capacity and cycle performance, and also significantly improve thermal stability, largely solving the common problem of poor cycle and thermal stability of high-nickel cathode materials in the industry. Comparative Example 1, however, did not employ a coating structure; after washing, the surface structure was damaged, lattice lithium was deposited, and the polarization resistance was relatively high, resulting in poorer overall electrochemical performance compared to the examples. Comparative Example 2 only used Ga2O3 coating, which did not form a perovskite phase structure coating layer, resulting in an unstable surface structure and worse electrochemical performance than the examples. Although Comparative Example 3 also formed a perovskite structure, it did not introduce Ga elements, resulting in low coating layer activity, high impedance, unstable surface structure, and poor capacity and high-temperature cycle performance.

Claims

1. A coated modified nickel-based cathode material, characterized in that, It includes a nickel-based cathode material matrix and an ABO3 perovskite-type composite oxide coating layer coated on the surface of the nickel-based cathode material matrix, wherein the chemical formula of the ABO3 perovskite-type composite oxide coating layer is AB. b Ga 1-b O 3-δ Where δ is the oxygen vacancy value, 0≤δ≤0.5, b≤0.8, the ionic radius of element A is ≥0.80Å, and the ionic radius of element B is ≤0.70Å.

2. The coated modified nickel-based cathode material as described in claim 1, characterized in that, Element A includes at least one of Na, K, La, Y, Sr, Ca, Ba, Gd, Sm, Eu, Dy, or Nd, and element B includes at least one of Fe, Co, Ni, Mn, Al, or Ti.

3. The coated modified nickel-based cathode material as described in claim 1, characterized in that, The molar ratio of element A to element Ga in the ABO3 perovskite-type composite oxide coating layer is (0.9-1.0):(0.2-1.0).

4. The coated modified nickel-based cathode material as described in claim 1, characterized in that, The mass of the ABO3 perovskite composite oxide coating layer accounts for 0.1%-1% of the mass of the nickel-based cathode material matrix.

5. The coated modified nickel-based cathode material according to any one of claims 1 to 4, characterized in that, The chemical formula of the nickel-based cathode material matrix is ​​Li z Ni 1-x-y Co x M y O2, wherein element M includes one or more of Mn or Al, 0.9≤z≤1.1, 0≤x≤0.2, 0≤y≤0.

2.

6. The coated modified nickel-based cathode material according to any one of claims 1 to 4, characterized in that, The modified nickel-based cathode material was subjected to a pressure of 99 MPa and a compaction density of 3.1-3.2 g / cm³. 3 Under these conditions, its powder conductivity is not less than 0.04 S / cm; The modified nickel-based cathode material, as tested by DSC, has a peak temperature of not less than 210℃.

7. A method for preparing a coated modified nickel-based cathode material as described in any one of claims 1 to 6, characterized in that, Includes the following steps: (1) The nickel cobalt manganese hydroxide precursor and the lithium source were mixed evenly and then sintered to obtain the sintered product; (2) The sintered product obtained in step (1) is washed with water and dried to obtain the washed product; (3) The water-washed product obtained in step (2) is mixed with gallium source, A-containing compound and B-containing compound, and then sintered to obtain the coated modified nickel-based cathode material.

8. The preparation method according to claim 7, characterized in that, In step (1), the lithium source is one or more of lithium hydroxide, lithium carbonate or lithium nitrate; the sintering process is carried out in an oxygen atmosphere and includes two sintering stages: first, the temperature is raised to 400-600℃ and held for 2-5 hours, and then the temperature is raised to 700-800℃ and held for 8-20 hours.

9. The preparation method according to claim 7, characterized in that, In step (2), the water washing temperature is 5-25℃, the solid-liquid mass ratio during the water washing process is 1.0-3.0, the water washing time is 2-5 min, and the stirring speed is 400-900 rpm.

10. The preparation method according to claim 7, characterized in that, In step (3), the gallium source is one or more of gallium trioxide, gallium trisulfide, and gallium hydroxide; the A-containing compound is one or more of oxides, hydroxides, chlorides, carbonates, or nitrates containing element A; and the B-containing compound is one or more of oxides, hydroxides, chlorides, carbonates, or nitrates containing element B.

11. The preparation method according to claim 7, characterized in that, In step (3), the sintering process is carried out in an oxygen atmosphere and includes two sintering stages: first, the temperature is raised to 100-300℃ and held for 1-5 hours, and then the temperature is raised to 500-700℃ and held for 4-12 hours.

12. A lithium-ion battery, characterized in that, It includes the coated modified nickel-based cathode material as described in any one of claims 1 to 6, or the coated modified nickel-based cathode material prepared by the preparation method as described in any one of claims 7 to 11.

13. An electrical appliance, characterized in that, Including the lithium-ion battery as described in claim 12.

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