Positive electrode active material with lithium fluoride layer as well as preparation method and application of positive electrode active material

Abstract

The invention provides a positive active material with a lithium fluoride layer as well as a preparation method and application of the positive active material. The positive active material comprises a high-nickel ternary positive material and the lithium fluoride layer covering the surface of the high-nickel ternary positive material, and the thickness of the lithium fluoride layer is 10-100 nm. In the positive electrode active material with the lithium fluoride layer, the surface of the high-nickel ternary positive electrode material is covered with the lithium fluoride layer, and lithium fluoride has excellent chemical stability, conductivity and lithium ion transmission rate, so that the positive electrode active material is coated with the lithium fluoride layer with the thickness of 10-100nm, thereby ensuring that the positive electrode active material has relatively good ion transmission performance; the internal strain and phase change of the high-nickel ternary positive electrode material are inhibited, and the risk that the high-nickel ternary positive electrode material generates cracks is reduced; the interface performance is improved, and the active material is isolated from the electrolyte, so that the risk of side reaction between the high-nickel ternary positive electrode material and the electrolyte is reduced, and the high-nickel ternary positive electrode material is prevented from being dissolved and delithiated.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries, and relates to a positive electrode active material with a lithium fluoride layer, and particularly to a positive electrode active material with a lithium fluoride layer, a preparation method thereof, and an application thereof. Background Art

[0002] With the wide application of lithium-ion batteries, the development of high-performance electrode materials has become a research hotspot. High-nickel ternary positive electrode materials are widely used in battery positive electrode materials due to their high capacity and relatively low cost. However, such materials have problems such as unstable structure and easy side reactions on the surface, which affect the cycle life and safety of the battery.

[0003] At present, element doping can significantly improve the electrochemical performance and cycle stability of high-nickel ternary positive electrode materials, but there are risks of excessive doping and problems of doping uniformity in the process of element doping, and it will also lead to a significant increase in cost. The use of nanosizing technology can increase the specific surface area of high-nickel ternary positive electrode materials, promote the rapid diffusion of lithium ions, and improve the high-rate discharge performance, but the synthesis conditions of nanosizing technology are difficult to control. The concentration gradient method can also improve the performance and stability of high-nickel ternary positive electrode materials, but the preparation process is difficult, the uniformity is difficult to control, and the cost will increase significantly, seriously restricting its large-scale production. Improving the electrolyte has significant advantages in improving the performance of lithium-ion batteries, but it is also accompanied by challenges in terms of cost, compatibility, and environment.

[0004] CN118738357A discloses a high-nickel ternary positive electrode material with low residual alkali, high specific capacity, and high cycle stability, and a preparation method thereof. The preparation method includes the preparation of a primary coating agent dispersion liquid, the mixing of the high-nickel ternary positive electrode material and the primary coating agent dispersion liquid, the vacuum drying of the primary mixed material, the solid-phase sintering of the high-nickel ternary positive electrode material with the primary coating, the preparation of a secondary coating agent dispersion liquid, the mixing of the high-nickel ternary positive electrode material matrix with the primary coating and the secondary coating agent dispersion liquid, and the vacuum drying of the secondary mixed material; the obtained high-nickel ternary positive electrode material includes an active substance with the molecular formula LiNi x Co y Mn z O2 (0.8 ≤ x < 1, 0 < y < 0.2, 0 < z < 0.2, and x + y + z = 1), and a coating layer formed by the primary co-coating of aluminum phosphate and lithium phosphate, and the secondary coating of a composite coating agent of graphene, carbon nanotubes, and conductive carbon black.

[0005] CN116830320A discloses a method for modifying the surface of a high-nickel ternary cathode material and its application. The method involves first preparing an alkyl lithium silicate solution, then mixing the alkyl lithium silicate solution with the high-nickel ternary cathode material using a spraying method or a solid-liquid blending method to react, followed by drying and heat treatment to obtain the modified high-nickel ternary cathode material. This invention applies alkyl lithium silicate to the modification of the high-nickel ternary cathode material. The hydrophilic oxygen-containing groups of the alkyl lithium silicate react with the hydrophilic oxygen-containing functional groups of the high-nickel ternary cathode material, exposing the hydrophobic alkyl groups and forming a hydrophobic protective coating. This reduces the surface energy and water absorption capacity of the high-nickel ternary cathode material.

[0006] The high-nickel ternary positive electrode materials disclosed in the prior art all have certain defects, such as structural instability and the problem that the surface easily undergoes side reactions with the electrolyte, which affects the cycle life and safety of the battery. Summary of the Invention

[0007] In view of the deficiencies in the prior art, the object of the present invention is to provide a positive electrode active material with a lithium fluoride layer, a preparation method and application thereof. In the positive electrode active material with a lithium fluoride layer provided by the present invention, the surface of the high-nickel ternary positive electrode material is covered with a lithium fluoride layer. Since lithium fluoride has excellent chemical stability, conductivity and lithium ion transmission rate, the coating of the lithium fluoride layer with a thickness of 10 to 100 nm ensures that the positive electrode active material has good ion transmission performance while suppressing the internal strain and phase change of the high-nickel ternary positive electrode material and reducing the risk of cracks in the high-nickel ternary positive electrode material; it also improves the interface performance, isolates the active material from the electrolyte, thereby reducing the risk of side reactions between the high-nickel ternary positive electrode material and the electrolyte, and prevents the high-nickel ternary positive electrode material from dissolving and delithiation; therefore, the positive electrode active material has excellent electrochemical properties.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a positive electrode active material having a lithium fluoride layer, wherein the positive electrode active material comprises a high-nickel ternary positive electrode material and a lithium fluoride layer covering the surface of the high-nickel ternary positive electrode material;

[0010] The thickness of the lithium fluoride layer is 10-100 nm.

[0011] The high-nickel ternary positive electrode material (NCM) described in the present invention is a common positive electrode material in the prior art. It refers to a lithium-ion battery positive electrode material with a nickel (Ni) content of ≥80%, including three elements: nickel, cobalt and manganese. Its high nickel content can significantly improve the material's specific capacity (≥180mAh / g) and energy density, and is mainly used in the field of electric vehicle power batteries.

[0012] In the positive electrode active material with a lithium fluoride layer provided by the present invention, the surface of the high-nickel ternary positive electrode material is covered with a lithium fluoride layer. Since lithium fluoride has excellent chemical stability, conductivity and lithium ion transmission rate, the internal strain and phase change of the high-nickel ternary positive electrode material are suppressed by the coating of the lithium fluoride layer, thereby reducing the risk of cracks in the high-nickel ternary positive electrode material, improving the stability of the high-nickel ternary positive electrode material, and thus improving the cycle stability of the positive electrode active material.

[0013] In the positive electrode active material with a lithium fluoride layer provided by the present invention, the lithium fluoride layer covering the surface of the high-nickel ternary positive electrode material can also improve the interface performance and isolate the active material from the electrolyte, thereby reducing the risk of side reactions between the high-nickel ternary positive electrode material and the electrolyte, while preventing the high-nickel ternary positive electrode material from dissolving and delithiation, further improving the cycle stability of the high-nickel ternary positive electrode material.

[0014] In the positive electrode active material with a lithium fluoride layer provided by the present invention, by limiting the thickness of the lithium fluoride layer covering the surface of the high-nickel ternary positive electrode material to 10 to 100 nm, while ensuring that the positive electrode active material has good ion transport performance, it also ensures that the lithium fluoride layer can effectively resist the strain inside the high-nickel ternary positive electrode material, thereby reducing the generation of cracks.

[0015] The thickness of the lithium fluoride layer in the present invention is 10 to 100 nm, for example, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm or 100 nm, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

[0016] Preferably, the D50 particle size of the high-nickel ternary positive electrode material is 2.5 to 3.8 μm, for example, it can be 2.5 μm, 2.6 μm, 2.7 μm, 2.8 μm, 2.9 μm, 3.0 μm, 3.1 μm, 3.2 μm, 3.3 μm, 3.4 μm, 3.5 μm, 3.6 μm, 3.7 μm or 3.8 μm, but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0017] Preferably, the thickness of the lithium fluoride layer is 30 to 70 nm, for example, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm or 70 nm, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0018] Preferably, the density of the lithium fluoride layer is 70% to 95%, for example, it can be 70%, 72%, 75%, 78%, 80%, 82%, 85%, 88%, 90%, 92% or 95%, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

[0019] Preferably, the porosity of the lithium fluoride layer is 5-30%, for example, it can be 5%, 6%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28% or 30%, but is not limited to the listed values, and other values not listed within this numerical range are also applicable.

[0020] The lithium fluoride layer covering the surface of the high-nickel ternary positive electrode material in the present invention has a higher density and lower porosity; first, the high-density lithium fluoride layer can more effectively block the direct contact between the electrolyte and the positive electrode active material, reduce side reactions, and thus reduce capacity decay; second, the high-density lithium fluoride layer can better buffer the stress generated by the volume change (such as lithium ion deintercalation) of the high-nickel ternary positive electrode material during the charge and discharge process, and prevent particles from breaking or pulverizing; third, the high-density lithium fluoride layer can regulate the surface lithium ion flux, reduce the problem of lithium dendrites or local overcharge caused by excessive local current density; finally, the dense structure of the high-density lithium fluoride layer can form a continuous electronic conductive network, further improving the overall electronic conductivity of the positive electrode active material and supporting high-rate charge and discharge.

[0021] In a second aspect, the present invention provides a method for preparing the positive electrode active material according to the first aspect, the preparation method comprising:

[0022] A lithium fluoride layer is deposited on the surface of the high-nickel ternary positive electrode material by magnetron sputtering and then annealed to obtain the positive electrode active material.

[0023] In the present invention, magnetron sputtering is used to deposit the lithium fluoride layer. As an efficient thin film deposition method, magnetron sputtering technology can deposit a uniform and dense film layer on the surface of the material.

[0024] The method for preparing the positive electrode active material provided by the present invention has a simple process, is suitable for large-scale production, and can effectively improve the cycle stability of the positive electrode active material.

[0025] Preferably, the argon pressure during the magnetron sputtering process is 0.05 to 0.2 Pa, the sputtering power is 150 to 250 W, the temperature is 100 to 300° C., and the distance between the target and the substrate is 8 to 12 cm. The argon pressure during the magnetron sputtering process of the present invention is 0.05 to 0.2 Pa, for example, it can be 0.05 Pa, 0.08 Pa, 0.1 Pa, 0.12 Pa, 0.15 Pa, 0.18 Pa or 0.2 Pa, but is not limited to the listed values. Other values not listed within this numerical range are also applicable.

[0026] The sputtering power in the magnetron sputtering process of the present invention is 150 to 250 W, for example, it can be 150 W, 170 W, 190 W, 200 W, 220 W, 240 W or 250 W, but is not limited to the listed values. Other values not listed within the numerical range are also applicable.

[0027] The temperature in the magnetron sputtering process of the present invention is 100-300°C, for example, it can be 100°C, 120°C, 140°C, 150°C, 160°C, 180°C, 200°C, 220°C, 240°C, 250°C, 260°C, 280°C or 300°C, but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0028] The distance between the target and the substrate during the magnetron sputtering process of the present invention is 8 to 12 cm, for example, it can be 8 cm, 8.5 cm, 9 cm, 9.5 cm, 10 cm, 10.5 cm, 11 cm, 11.5 cm or 12 cm, but is not limited to the listed values. Other values not listed within this numerical range are also applicable.

[0029] Preferably, the annealing includes heating, holding and cooling in sequence.

[0030] Preferably, the heating rate is 1-10°C / min, and the end temperature is 160-240°C.

[0031] The heating rate described in the present invention is 1 to 10°C / min, for example, it can be 1°C / min, 2°C / min, 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min or 10°C / min, but is not limited to the listed values. Other values not listed within this numerical range are also applicable.

[0032] The end temperature of the heating in the present invention is 160-240°C, for example, it can be 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C or 240°C, but is not limited to the listed values. Other values not listed within this numerical range are also applicable.

[0033] Preferably, the insulation time is 10 to 20 minutes, for example, it can be 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes, 15 minutes, 16 minutes, 17 minutes, 18 minutes, 19 minutes or 20 minutes, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0034] Preferably, the cooling rate is 1-5°C / min, and the end temperature is 20-60°C.

[0035] The cooling rate described in the present invention is 1 to 5°C / min, for example, it can be 1°C / min, 1.5°C / min, 2°C / min, 2.5°C / min, 3°C / min, 3.5°C / min, 4°C / min, 4.5°C / min or 5°C / min, but is not limited to the listed values. Other values not listed within this numerical range are also applicable.

[0036] The end temperature of the cooling in the present invention is 20-60°C, for example, it can be 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C or 60°C, but is not limited to the listed values. Other values not listed within this numerical range are also applicable.

[0037] Preferably, the method for preparing the high-nickel ternary positive electrode material comprises:

[0038] A nickel-cobalt-manganese ternary mixed salt solution, a precipitant solution and a complexing agent solution are added concurrently to the reaction bottom liquid to carry out a co-precipitation reaction to obtain a high-nickel ternary precursor; the obtained high-nickel ternary precursor is mixed with a lithium source and then heat-treated to obtain a high-nickel ternary positive electrode material.

[0039] Preferably, the concentration of the complexing agent in the reaction base solution is 4-8 g / L, and the pH is 10.0-12.0.

[0040] The concentration of the complexing agent in the reaction base solution of the present invention is 4 to 8 g / L, for example, 4 g / L, 5 g / L, 6 g / L, 7 g / L or 8 g / L, but is not limited to the listed values. Other values not listed within the numerical range are also applicable.

[0041] The pH of the reaction base solution of the present invention is 10.0-12.0, for example, it can be 10.0, 10.2, 10.4, 10.6, 10.8, 11.0, 11.2, 11.4, 11.6, 11.8 or 12.0, but is not limited to the listed values. Other values not listed within the numerical range are also applicable.

[0042] Preferably, the total concentration of metal salts in the nickel-cobalt-manganese ternary mixed salt solution is 80-120 g / L, for example, it can be 80 g / L, 85 g / L, 90 g / L, 95 g / L, 100 g / L, 105 g / L, 110 g / L, 115 g / L or 120 g / L, but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0043] Preferably, the total concentration of metal ions in the nickel-cobalt-manganese ternary mixed salt solution is 1 to 2 mol / L.

[0044] Preferably, based on the total molar amount of metal ions in the nickel-cobalt-manganese ternary mixed salt solution, the molar amount of nickel ions in the nickel-cobalt-manganese ternary mixed salt solution is not less than 90%, for example, it can be 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%, but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0045] Preferably, the anions in the nickel-cobalt-manganese ternary mixed salt solution include any one of sulfate ions, chloride ions or nitrate ions, or a combination of at least two of them. Typical but non-limiting combinations include a combination of sulfate ions and chloride ions, a combination of chloride ions and nitrate ions, a combination of sulfate ions and nitrate ions, or a combination of sulfate ions, chloride ions and nitrate ions.

[0046] Preferably, the precipitant in the precipitant solution comprises any one or a combination of at least two of sodium hydroxide, sodium carbonate or sodium oxalate. Typical but non-limiting combinations include a combination of sodium hydroxide and sodium carbonate, a combination of sodium carbonate and sodium oxalate, a combination of sodium hydroxide and sodium oxalate, or a combination of sodium hydroxide, sodium carbonate and sodium oxalate.

[0047] Preferably, the mass concentration of the precipitant in the precipitant solution is 28 to 32 wt%, for example, it can be 28 wt%, 29 wt%, 30 wt%, 31 wt% or 32 wt%, but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0048] Preferably, the complexing agent in the complexing agent solution includes any one or a combination of at least two of ammonia, sodium carbonate or sodium oxalate. Typical but non-limiting combinations include a combination of ammonia and sodium carbonate, a combination of sodium carbonate and sodium oxalate, a combination of ammonia and sodium oxalate, or a combination of ammonia, sodium carbonate and sodium oxalate.

[0049] Preferably, the mass concentration of the complexing agent in the complexing agent solution is 10-20wt%, for example, it can be 10wt%, 12wt%, 14wt%, 16wt%, 18wt% or 20wt%, but is not limited to the listed values, and other unlisted values within this numerical range are also applicable.

[0050] Preferably, during the parallel addition process, the addition flow rate of the nickel-cobalt-manganese ternary mixed salt solution is 6-10 L / h, the addition flow rate of the precipitant solution is 2-3 L / h, and the addition flow rate of the complexing agent solution is 0.3-0.6 L / h.

[0051] In the process of parallel addition described in the present invention, the addition flow rate of the nickel-cobalt-manganese ternary mixed salt solution is 6 to 10 L / h, for example, it can be 6 L / h, 7 L / h, 8 L / h, 9 L / h or 10 L / h, but is not limited to the listed values, and other values not listed within this numerical range are also applicable.

[0052] The addition flow rate of the precipitant solution in the parallel addition process of the present invention is 2 to 3 L / h, for example, it can be 2 L / h, 2.2 L / h, 2.4 L / h, 2.6 L / h, 2.8 L / h or 3 L / h, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

[0053] The addition flow rate of the complexing agent solution during the parallel addition process of the present invention is 0.3 to 0.6 L / h, for example, it can be 0.3 L / h, 0.4 L / h, 0.5 L / h or 0.6 L / h, but is not limited to the listed values. Other values not listed within the numerical range are also applicable.

[0054] Preferably, during the coprecipitation reaction, the pH of the reaction system is controlled to be 10.0-12.0, the ammonia concentration is 4-8 g / L, and the temperature is 40-60°C.

[0055] During the coprecipitation reaction of the present invention, the pH of the reaction system is controlled to be 10.0-12.0, for example, it can be 10.0, 10.2, 10.4, 10.6, 10.8, 11.0, 11.2, 11.4, 11.6, 11.8 or 12.0, but is not limited to the listed values. Other values not listed within this numerical range are also applicable.

[0056] During the coprecipitation reaction of the present invention, the ammonia concentration of the reaction system is controlled to be 4 to 8 g / L, for example, 4 g / L, 5 g / L, 6 g / L, 7 g / L or 8 g / L, but is not limited to the listed values, and other values not listed within this numerical range are also applicable.

[0057] During the coprecipitation reaction of the present invention, the temperature of the reaction system is controlled to be 40-60°C, for example, 40°C, 45°C, 50°C, 55°C or 60°C, but is not limited to the listed values. Other values not listed within the numerical range are also applicable.

[0058] Preferably, the coprecipitation reaction is terminated until the D50 particle size of the precipitate reaches 3 to 4 μm, for example, it can be 3.0 μm, 3.1 μm, 3.2 μm, 3.3 μm, 3.4 μm, 3.5 μm, 3.6 μm, 3.7 μm, 3.8 μm, 3.9 μm or 4.0 μm, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0059] Preferably, the method for preparing the high-nickel ternary positive electrode material further comprises a secondary coprecipitation between the coprecipitation reaction and the heat treatment;

[0060] During the secondary coprecipitation, the addition of the nickel-cobalt-manganese ternary mixed salt solution, the precipitant solution and the complexing agent solution is stopped, and the coprecipitation is continued until the materials in the reaction system react completely to obtain a high-nickel ternary precursor.

[0061] Preferably, the lithium source includes any one or a combination of at least two of lithium carbonate, lithium hydroxide, lithium acetate or lithium nitrate. Typical but non-limiting combinations include a combination of lithium carbonate and lithium hydroxide, a combination of lithium acetate and lithium nitrate, a combination of lithium hydroxide and lithium acetate, or a combination of lithium carbonate, lithium hydroxide and lithium nitrate.

[0062] Preferably, the heat treatment temperature is 400-600° C., and the time is 250-350 min.

[0063] The heat treatment temperature in the present invention is 400-600°C, for example, 400°C, 450°C, 500°C, 550°C or 600°C, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0064] The heat treatment time in the present invention is 250 to 350 minutes, for example, it can be 250 minutes, 270 minutes, 290 minutes, 300 minutes, 320 minutes, 340 minutes or 350 minutes, but is not limited to the listed values. Other values not listed within the numerical range are also applicable.

[0065] As a preferred technical solution of the preparation method of the present invention, the preparation method comprises:

[0066] (1) The first stage: a nickel-cobalt-manganese ternary mixed salt solution with a total metal ion concentration of 1 to 2 mol / L, a sodium hydroxide solution with a mass concentration of 28 to 32 wt%, and an ammonia solution with a mass concentration of 10 to 20 wt% are added concurrently to a reaction base solution with a complexing agent concentration of 4 to 8 g / L and a pH of 10.0 to 12.0 to carry out a coprecipitation reaction. During the coprecipitation reaction, the pH of the reaction system is controlled to be 10.0 to 12.0, the ammonia concentration is 4 to 8 g / L, and the temperature is 40 to 60° C., until the D50 particle size of the precipitate reaches 3 to 4 μm;

[0067] During the parallel addition process, the flow rate of adding the nickel-cobalt-manganese ternary mixed salt solution is 6 to 10 L / h, the flow rate of adding the precipitant solution is 2 to 3 L / h, and the flow rate of adding the complexing agent solution is 0.3 to 0.6 L / h;

[0068] The second stage: stop adding the nickel-cobalt-manganese ternary mixed salt solution, the precipitant solution and the complexing agent solution, and continue the coprecipitation reaction until the materials in the reaction system react completely to obtain a high-nickel ternary precursor;

[0069] (2) mixing the high-nickel ternary precursor obtained in step (1) with a lithium source, and performing a heat treatment at 400-600° C. for 250-350 min to obtain a high-nickel ternary positive electrode material;

[0070] (3) depositing a lithium fluoride layer on the surface of the high-nickel ternary cathode material obtained in step (2) by magnetron sputtering, wherein the argon pressure during the magnetron sputtering process is 0.05 to 0.2 Pa, the sputtering power is 150 to 250 W, the temperature is 100 to 300° C., and the distance between the target and the substrate is 8 to 12 cm;

[0071] Then, the temperature is raised to 160-240° C. at a rate of 1-10° C. / min, kept at this temperature for 10-20 minutes, and then lowered to 20-60° C. at a rate of 1-5° C. / min to obtain the positive electrode active material.

[0072] In a third aspect, the present invention provides a battery comprising the positive electrode active material according to the first aspect.

[0073] The numerical range described in the present invention includes not only the point values listed above, but also any point values between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the range.

[0074] Compared with the prior art, the present invention has the following beneficial effects:

[0075] (1) In the positive electrode active material having a lithium fluoride layer provided by the present invention, the surface of the high-nickel ternary positive electrode material is covered with a lithium fluoride layer. Since lithium fluoride has excellent chemical stability, electrical conductivity and lithium ion transmission rate, the internal strain and phase change of the high-nickel ternary positive electrode material are suppressed by the coating of the lithium fluoride layer, the risk of cracking of the high-nickel ternary positive electrode material is reduced, the stability of the high-nickel ternary positive electrode material is improved, and thus the cycle stability of the positive electrode active material is improved;

[0076] (2) In the positive electrode active material having a lithium fluoride layer provided by the present invention, the lithium fluoride layer covering the surface of the high-nickel ternary positive electrode material can also improve the interface performance and isolate the active material from the electrolyte, thereby reducing the risk of side reactions between the high-nickel ternary positive electrode material and the electrolyte while preventing the high-nickel ternary positive electrode material from dissolving and delithiation, further improving the cycle stability of the high-nickel ternary positive electrode material;

[0077] (3) In the positive electrode active material having a lithium fluoride layer provided by the present invention, by limiting the thickness of the lithium fluoride layer covering the surface of the high nickel ternary positive electrode material to 10 to 100 nm, while ensuring that the positive electrode active material has good ion transport performance, it also ensures that the lithium fluoride layer can effectively resist the strain inside the high nickel ternary positive electrode material, thereby reducing the generation of cracks;

[0078] (4) The lithium fluoride layer covering the surface of the high-nickel ternary positive electrode material in the present invention has a higher density and lower porosity; first, the high-density lithium fluoride layer can more effectively block the direct contact between the electrolyte and the positive electrode active material, reduce side reactions, and thus reduce capacity decay; second, the high-density lithium fluoride layer can better buffer the stress generated by the volume change (such as lithium ion deintercalation) of the high-nickel ternary positive electrode material during the charge and discharge process, and prevent the particles from breaking or pulverizing; third, the high-density lithium fluoride layer can regulate the surface lithium ion flux, reducing the problem of lithium dendrites or local overcharge caused by excessive local current density; finally, the dense structure of the high-density lithium fluoride layer can form a continuous electronic conductive network, further improving the overall electronic conductivity of the positive electrode active material and supporting high-rate charge and discharge;

[0079] (5) The present invention adopts magnetron sputtering to deposit the lithium fluoride layer. Magnetron sputtering technology is an efficient thin film deposition method that can deposit a uniform and dense film layer on the material surface;

[0080] (6) The preparation method of the positive electrode active material provided by the present invention has a simple process, is suitable for large-scale production, and can effectively improve the cycle stability of the positive electrode active material. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] Figure 1 is a SEM image of the positive electrode active material having a lithium fluoride layer provided in Example 1. DETAILED DESCRIPTION

[0082] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0083] Example 1

[0084] This embodiment provides a positive electrode active material having a lithium fluoride layer, the positive electrode active material comprising a high nickel ternary positive electrode material having a D50 particle size of 3.2 μm, and a lithium fluoride layer having a thickness of 50 nm, a density of 82%, and a porosity of 18% covering the surface of the high nickel ternary positive electrode material;

[0085] The preparation method of the positive electrode active material comprises:

[0086] (1) The first stage: a nickel-cobalt-manganese ternary mixed salt solution with a total metal ion concentration of 1.5 mol / L (a molar ratio of nickel ion, cobalt ion, and manganese ion of 9.4:0.3:0.3), a sodium hydroxide solution with a mass concentration of 30 wt %, and an ammonia solution with a mass concentration of 15 wt % were added concurrently to a reaction base solution with a complexing agent concentration of 6 g / L and a pH of 11.0, to carry out a coprecipitation reaction. During the coprecipitation reaction, the pH of the reaction system was controlled to be 11.0, the ammonia concentration was 6 g / L, and the temperature was 50° C., until the D50 particle size of the precipitate reached 3.5 μm;

[0087] During the parallel addition process, the addition flow rate of the nickel-cobalt-manganese ternary mixed salt solution is 8 L / h, the addition flow rate of the sodium hydroxide solution is 2.5 L / h, and the addition flow rate of the ammonia water is 0.45 L / h;

[0088] The second stage: stop adding the nickel-cobalt-manganese ternary mixed salt solution, sodium hydroxide solution and ammonia water, and continue the coprecipitation reaction until the materials in the reaction system react completely to obtain a high-nickel ternary precursor;

[0089] (2) mixing the high-nickel ternary precursor obtained in step (1) with a lithium source, and performing a heat treatment at 500° C. for 300 min to obtain a high-nickel ternary positive electrode material;

[0090] (3) depositing a lithium fluoride layer on the surface of the high-nickel ternary cathode material obtained in step (2) by magnetron sputtering, wherein the argon pressure during the magnetron sputtering process is 0.12 Pa, the sputtering power is 200 W, the temperature is 200° C., and the distance between the target and the substrate is 10 cm;

[0091] The temperature was then raised to 200° C. at a rate of 5° C. / min, kept at that temperature for 15 minutes, and then lowered to 40° C. at a rate of 3° C. / min to obtain the positive electrode active material.

[0092] The positive electrode active material obtained in this embodiment was tested using a scanning electron microscope, and the SEM image of the positive electrode active material with a lithium fluoride layer provided in this embodiment was obtained as shown in FIG. Figure 1 shown.

[0093] Example 2

[0094] This embodiment provides a positive electrode active material having a lithium fluoride layer, the positive electrode active material comprising a high nickel ternary positive electrode material having a D50 particle size of 3.8 μm, and a lithium fluoride layer having a thickness of 30 nm, a density of 90%, and a porosity of 10% covering the surface of the high nickel ternary positive electrode material;

[0095] The preparation method of the lithium fluoride layer comprises:

[0096] (1) The first stage: a nickel-cobalt-manganese ternary mixed salt solution with a total metal ion concentration of 1.2 mol / L (a molar ratio of nickel ion, cobalt ion, and manganese ion of 9.4:0.3:0.3), a sodium hydroxide solution with a mass concentration of 29 wt%, and an ammonia solution with a mass concentration of 12 wt% were added concurrently to a reaction base solution with a complexing agent concentration of 5 g / L and a pH of 10.5, to carry out a coprecipitation reaction. During the coprecipitation reaction, the pH of the reaction system was controlled to be 10.5, the ammonia concentration was 5 g / L, and the temperature was 45°C until the D50 particle size of the precipitate reached 3.2 μm.

[0097] During the parallel addition process, the addition flow rate of the nickel-cobalt-manganese ternary mixed salt solution is 7 L / h, the addition flow rate of the sodium hydroxide solution is 2.2 L / h, and the addition flow rate of the ammonia water is 0.36 L / h;

[0098] The second stage: stop adding the nickel-cobalt-manganese ternary mixed salt solution, sodium hydroxide solution and ammonia water, and continue the coprecipitation reaction until the materials in the reaction system react completely to obtain a high-nickel ternary precursor;

[0099] (2) mixing the high-nickel ternary precursor obtained in step (1) with lithium hydroxide, and performing a heat treatment at 550° C. for 280 min to obtain a high-nickel ternary positive electrode material;

[0100] (3) depositing a lithium fluoride layer on the surface of the high-nickel ternary cathode material obtained in step (2) by magnetron sputtering, wherein the argon pressure during the magnetron sputtering process is 0.16 Pa, the sputtering power is 180 W, the temperature is 250° C., and the distance between the target and the substrate is 9 cm;

[0101] The temperature was then raised to 180° C. at a rate of 3° C. / min, maintained at that temperature for 18 minutes, and then lowered to 50° C. at a rate of 2° C. / min to obtain the positive electrode active material.

[0102] Example 3

[0103] This embodiment provides a positive electrode active material having a lithium fluoride layer, the positive electrode active material comprising a high-nickel ternary positive electrode material having a D50 particle size of 3.5 μm, and a lithium fluoride layer having a thickness of 70 nm, a density of 75%, and a porosity of 25% covering the surface of the high-nickel ternary positive electrode material;

[0104] The preparation method of the lithium fluoride layer comprises:

[0105] (1) The first stage: a nickel-cobalt-manganese ternary mixed salt solution (the molar ratio of nickel ion, cobalt ion and manganese ion is 9.4:0.3:0.3) with a total metal ion concentration of 1.8 mol / L, a sodium hydroxide solution with a mass concentration of 31 wt% and an ammonia solution with a mass concentration of 18 wt% were added concurrently to a reaction base liquid with a complexing agent concentration of 7 g / L and a pH of 11.5, to carry out a coprecipitation reaction. During the coprecipitation reaction, the pH of the reaction system was controlled to be 11.5, the ammonia concentration was 7 g / L, and the temperature was 55°C until the D50 particle size of the precipitate reached 3.8 μm.

[0106] During the parallel addition process, the addition flow rate of the nickel-cobalt-manganese ternary mixed salt solution is 9 L / h, the addition flow rate of the sodium hydroxide solution is 2.8 L / h, and the addition flow rate of the ammonia water is 0.52 L / h;

[0107] The second stage: stop adding the nickel-cobalt-manganese ternary mixed salt solution, sodium hydroxide solution and ammonia water, and continue the coprecipitation reaction until the materials in the reaction system react completely to obtain a high-nickel ternary precursor;

[0108] (2) mixing the high-nickel ternary precursor obtained in step (1) with lithium hydroxide, and performing a heat treatment at 450° C. for 320 min to obtain a high-nickel ternary positive electrode material;

[0109] (3) depositing a lithium fluoride layer on the surface of the high-nickel ternary cathode material obtained in step (2) by magnetron sputtering, wherein the argon pressure during the magnetron sputtering process is 0.08 Pa, the sputtering power is 220 W, the temperature is 150° C., and the distance between the target and the substrate is 11 cm;

[0110] The temperature was then raised to 220° C. at a rate of 8° C. / min, maintained at that temperature for 12 minutes, and then lowered to 30° C. at a rate of 4° C. / min to obtain the positive electrode active material.

[0111] Example 4

[0112] This embodiment provides a positive electrode active material having a lithium fluoride layer, the positive electrode active material comprising a high-nickel ternary positive electrode material having a D50 particle size of 3.8 μm, and a lithium fluoride layer having a thickness of 100 nm, a density of 70%, and a porosity of 30% covering the surface of the high-nickel ternary positive electrode material;

[0113] The preparation method of the lithium fluoride layer comprises:

[0114] (1) The first stage: a nickel-cobalt-manganese ternary mixed salt solution (the molar ratio of nickel ion, cobalt ion and manganese ion is 9.4:0.3:0.3) with a total metal ion concentration of 2 mol / L, a sodium hydroxide solution with a mass concentration of 32 wt% and an ammonia solution with a mass concentration of 20 wt% were added concurrently to a reaction base liquid with a complexing agent concentration of 8 g / L and a pH of 12.0, to carry out a coprecipitation reaction. During the coprecipitation reaction, the pH of the reaction system was controlled to be 12.0, the ammonia concentration was 8 g / L, and the temperature was 40°C until the D50 particle size of the precipitate reached 4 μm;

[0115] During the parallel addition process, the flow rate of the nickel-cobalt-manganese ternary mixed salt solution is 10 L / h, the flow rate of the sodium hydroxide solution is 3 L / h, and the flow rate of the ammonia water is 0.6 L / h;

[0116] The second stage: stop adding the nickel-cobalt-manganese ternary mixed salt solution, sodium hydroxide solution and ammonia water, and continue the coprecipitation reaction until the materials in the reaction system react completely to obtain a high-nickel ternary precursor;

[0117] (2) mixing the high-nickel ternary precursor obtained in step (1) with lithium hydroxide, and performing a heat treatment at 400° C. for 350 min to obtain a high-nickel ternary positive electrode material;

[0118] (3) depositing a lithium fluoride layer on the surface of the high-nickel ternary cathode material obtained in step (2) by magnetron sputtering, wherein the argon pressure during the magnetron sputtering process is 0.2 Pa, the sputtering power is 150 W, the temperature is 300° C., and the distance between the target and the substrate is 12 cm;

[0119] The temperature was then raised to 240° C. at a rate of 10° C. / min, kept at that temperature for 10 minutes, and then lowered to 60° C. at a rate of 5° C. / min to obtain the positive electrode active material.

[0120] Example 5

[0121] This embodiment provides a positive electrode active material having a lithium fluoride layer, the positive electrode active material comprising a high-nickel ternary positive electrode material having a D50 particle size of 2.5 μm, and a lithium fluoride layer having a thickness of 10 nm, a density of 95%, and a porosity of 5% covering the surface of the high-nickel ternary positive electrode material;

[0122] The preparation method of the lithium fluoride layer comprises:

[0123] (1) The first stage: a nickel-cobalt-manganese ternary mixed salt solution (a molar ratio of nickel ion, cobalt ion and manganese ion of 9.4:0.3:0.3) with a total metal ion concentration of 1 mol / L, a sodium hydroxide solution with a mass concentration of 28 wt% and an ammonia solution with a mass concentration of 10 wt% were added concurrently to a reaction base liquid with a complexing agent concentration of 4 g / L and a pH of 10.0, and a coprecipitation reaction was carried out. During the coprecipitation reaction, the pH of the reaction system was controlled to be 10.0, the ammonia concentration was controlled to be 4 g / L, and the temperature was controlled to be 60°C, until the D50 particle size of the precipitate reached 3 μm;

[0124] During the parallel addition process, the flow rate of the nickel-cobalt-manganese ternary mixed salt solution is 6 L / h, the flow rate of the sodium hydroxide solution is 2 L / h, and the flow rate of the ammonia water is 0.3 L / h;

[0125] The second stage: stop adding the nickel-cobalt-manganese ternary mixed salt solution, sodium hydroxide solution and ammonia water, and continue the coprecipitation reaction until the materials in the reaction system react completely to obtain a high-nickel ternary precursor;

[0126] (2) mixing the high-nickel ternary precursor obtained in step (1) with lithium hydroxide, and performing a heat treatment at 600° C. for 250 min to obtain a high-nickel ternary positive electrode material;

[0127] (3) depositing a lithium fluoride layer on the surface of the high-nickel ternary cathode material obtained in step (2) by magnetron sputtering, wherein the argon pressure during the magnetron sputtering process is 0.05 Pa, the sputtering power is 250 W, the temperature is 100° C., and the distance between the target and the substrate is 8 cm;

[0128] The temperature was then raised to 160° C. at a rate of 1° C. / min, maintained at that temperature for 20 minutes, and then lowered to 20° C. at a rate of 1° C. / min to obtain the positive electrode active material.

[0129] Example 6

[0130] This embodiment provides a positive electrode active material having a lithium fluoride layer, except that the lithium fluoride layer has a density of 60% and a porosity of 40%;

[0131] That is, in step (3) of the method for preparing the positive electrode active material, the argon pressure during the magnetron sputtering process is 0.25 Pa, the sputtering power is 120 W, the temperature is 350° C., and the distance between the target and the substrate is 14 cm. The rest is the same as in Example 5.

[0132] Example 7

[0133] This embodiment provides a positive electrode active material having a lithium fluoride layer, except that the lithium fluoride layer has a density of 98% and a porosity of 2%;

[0134] That is, in step (3) of the method for preparing the positive electrode active material, the argon pressure during the magnetron sputtering process is 0.05 Pa, the sputtering power is 300 W, the temperature is 80° C., and the distance between the target and the substrate is 8 cm. The rest is the same as in Example 5.

[0135] Example 8

[0136] This embodiment provides a positive electrode active material having a lithium fluoride layer. Except that in step (3) of the method for preparing the positive electrode active material, the temperature is raised to 130° C. and then kept warm after the lithium fluoride layer is deposited by magnetron sputtering, the rest is the same as that of Example 5.

[0137] Example 9

[0138] This embodiment provides a positive electrode active material having a lithium fluoride layer. Except that in step (3) of the method for preparing the positive electrode active material, the temperature is raised to 280° C. and then kept warm after the lithium fluoride layer is deposited by magnetron sputtering, the rest is the same as that of Example 5.

[0139] Comparative Example 1

[0140] This comparative example provides a positive electrode active material having a lithium fluoride layer, which is the same as Example 5 except that the thickness of the lithium fluoride layer is 3 nm.

[0141] Comparative Example 2

[0142] This comparative example provides a positive electrode active material having a lithium fluoride layer, which is the same as Example 5 except that the thickness of the lithium fluoride layer is 120 nm and the positive electrode active material step (3) is omitted.

[0143] Comparative Example 3

[0144] This comparative example provides a positive electrode active material having a lithium fluoride layer, which is the same as Example 5 except that the lithium fluoride layer covering the surface of the high-nickel ternary positive electrode material is omitted.

[0145] A lithium-ion battery was prepared using the positive electrode active materials provided in the above embodiments and comparative examples: the obtained positive electrode material, conductive carbon black SP (TIMCAL) and polyvinylidene fluoride PVDF (HSV900) were mixed in a mass ratio of 90:5:5, and N-methylpyrrolidone was used as the solvent. The mixture was stirred into a slurry, and the obtained slurry was evenly coated on an aluminum foil with a scraper with a coating gap of 100 μm; after coating, it was first blown dry, then rolled and cut into circular electrode sheets, and then vacuum dried at 120°C and the electrode sheets were weighed to obtain a button half-cell positive electrode sheet; a metal lithium sheet was selected as the negative electrode, a PP microporous membrane was selected as the diaphragm, and a lithium battery basic electrolyte was selected as the electrolyte. The positive electrode sheet, the metal lithium sheet, the diaphragm and the electrolyte were assembled to obtain a button battery.

[0146] The obtained button battery was charged and discharged at 0.1C / 0.1C, and the charge and discharge test was carried out in the voltage window of 2.8-4.3V. The first charge and discharge efficiency (1C / 0.1C discharge capacity ratio), 0.1C rate performance and capacity retention rate after 100 cycles at 1C of the button battery were obtained as shown in Table 1.

[0147] Table 1

[0148]

[0149] From Table 1 and Figure 1 We can get:

[0150] (1) The batteries prepared using the positive electrode active materials having a lithium fluoride layer provided in Examples 1 to 5 exhibited high initial charge and discharge efficiency, high rate performance, and excellent cycle stability;

[0151] (2) By comparing Example 5 with Examples 6 and 7, it can be seen that the density and porosity of the lithium fluoride layer in the present invention affect the performance of the positive electrode active material and the battery; when the density of the lithium fluoride layer is 70-95% and the porosity is 5-30%, the positive electrode active material and the battery show better performance. This is because when the density of the lithium fluoride layer is 70-95% and the porosity is 5-30%, the ion conductivity and interface stability of the positive electrode active material can be balanced, thereby optimizing the cycle life and rate performance of the battery;

[0152] (3) By comparing Example 5 with Examples 8 and 9, it can be seen that the terminal temperature of the temperature increase after the magnetron sputtering deposition of the lithium fluoride layer in step (3) of the preparation method of the positive electrode active material of the present invention, that is, the holding temperature, will affect the performance of the positive electrode active material and the battery; when the holding temperature is 160-240°C, the positive electrode active material and the battery show better performance. This is because when the holding temperature is 160-240°C, the crystallinity and interface bonding of the lithium fluoride layer can be optimized by temperature, the ion conductivity can be enhanced and defects can be reduced, and at the same time, the high-temperature decomposition of the lithium fluoride layer can be avoided, thereby improving the capacity, rate performance and cycle life of the battery;

[0153] (4) By comparing Example 5 with Comparative Examples 1 to 3, it can be seen that in the positive electrode active material having a lithium fluoride layer provided by the present invention, the surface of the high-nickel ternary positive electrode material is covered with a lithium fluoride layer. Since lithium fluoride has excellent chemical stability, electrical conductivity and lithium ion transmission rate, the internal strain and phase change of the high-nickel ternary positive electrode material are suppressed by the coating of the lithium fluoride layer, the risk of cracking of the high-nickel ternary positive electrode material is reduced, the stability of the high-nickel ternary positive electrode material is improved, and thus the cycle stability of the positive electrode active material is improved;

[0154] In the positive electrode active material having a lithium fluoride layer provided by the present invention, the lithium fluoride layer covering the surface of the high-nickel ternary positive electrode material can also improve the interface performance and isolate the active material from the electrolyte, thereby reducing the risk of side reactions between the high-nickel ternary positive electrode material and the electrolyte while preventing the high-nickel ternary positive electrode material from dissolving and delithiation, further improving the cycle stability of the high-nickel ternary positive electrode material;

[0155] In the positive electrode active material having a lithium fluoride layer provided by the present invention, by limiting the thickness of the lithium fluoride layer covering the surface of the high-nickel ternary positive electrode material to 10 to 100 nm, while ensuring that the positive electrode active material has good ion transport performance, it also ensures that the lithium fluoride layer can effectively resist the strain inside the high-nickel ternary positive electrode material, thereby reducing the generation of cracks;

[0156] The lithium fluoride layer covering the surface of the high-nickel ternary positive electrode material in the present invention has a higher density and lower porosity; first, the high-density lithium fluoride layer can more effectively block direct contact between the electrolyte and the positive electrode active material, reduce side reactions, and thus reduce capacity decay; second, the high-density lithium fluoride layer can better buffer the stress generated by the volume change (such as lithium ion deintercalation) of the high-nickel ternary positive electrode material during the charge and discharge process, and prevent particles from breaking or pulverizing; second, the high-density lithium fluoride layer can regulate the surface lithium ion flux, reducing the problem of lithium dendrites or local overcharge caused by excessive local current density; finally, the dense structure of the high-density lithium fluoride layer can form a continuous electronic conductive network, further improving the overall electronic conductivity of the positive electrode active material and supporting high-rate charge and discharge;

[0157] In the present invention, magnetron sputtering is used to deposit the lithium fluoride layer. Magnetron sputtering technology is an efficient thin film deposition method that can deposit a uniform and dense film layer on the material surface;

[0158] The method for preparing the positive electrode active material provided by the present invention has a simple process, is suitable for large-scale production, and can effectively improve the cycle stability of the positive electrode active material.

[0159] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and disclosure scope of the present invention.

Claims

1. A positive electrode active material having a lithium fluoride layer, characterized in that The positive electrode active material includes a high-nickel ternary positive electrode material and a lithium fluoride layer covering the surface of the high-nickel ternary positive electrode material; The thickness of the lithium fluoride layer is 10-100 nm.

2. The positive electrode active material according to claim 1, characterized in that The D50 particle size of the high-nickel ternary positive electrode material is 2.5 to 3.8 μm.

3. The positive electrode active material according to claim 1 or 2, characterized in that The thickness of the lithium fluoride layer is 30-70 nm.

4. The positive electrode active material according to any one of claims 1 to 3, characterized in that The density of the lithium fluoride layer is 70-95%; Preferably, the porosity of the lithium fluoride layer is 5-30%.

5. A method for preparing the positive electrode active material according to any one of claims 1 to 4, characterized in that: The preparation method comprises: A lithium fluoride layer is deposited on the surface of the high-nickel ternary positive electrode material by magnetron sputtering and then annealed to obtain the positive electrode active material.

6. The preparation method according to claim 5, characterized in that During the magnetron sputtering process, the argon pressure is 0.05-0.2 Pa, the sputtering power is 150-250 W, the temperature is 100-300° C., and the distance between the target and the substrate is 8-12 cm.

7. The preparation method according to claim 5 or 6, characterized in that: The annealing includes heating, holding and cooling in sequence; Preferably, the heating rate is 1-10°C / min, and the end temperature is 160-240°C; Preferably, the insulation time is 10 to 20 minutes; Preferably, the cooling rate is 1-5°C / min, and the end temperature is 20-60°C.

8. The preparation method according to any one of claims 5 to 7, characterized in that The method for preparing the high-nickel ternary positive electrode material comprises: Adding a nickel-cobalt-manganese ternary mixed salt solution, a precipitant solution, and a complexing agent solution concurrently to the reaction base liquid to perform a coprecipitation reaction to obtain a high-nickel ternary precursor; mixing the obtained high-nickel ternary precursor with a lithium source and then performing a heat treatment to obtain a high-nickel ternary positive electrode material; Preferably, the coprecipitation reaction is terminated until the D50 particle size of the precipitate reaches 2.5 to 3.8 μm; Preferably, the method for preparing the high-nickel ternary positive electrode material further comprises a secondary coprecipitation between the coprecipitation reaction and the heat treatment; During the secondary coprecipitation, the addition of the nickel-cobalt-manganese ternary mixed salt solution, the precipitant solution, and the complexing agent solution is stopped, and the coprecipitation is continued until the materials in the reaction system react completely to obtain a high-nickel ternary precursor; Preferably, the heat treatment temperature is 400-600° C., and the time is 250-350 min.

9. The preparation method according to any one of claims 5 to 8, characterized in that: The preparation method comprises: (1) The first stage: a nickel-cobalt-manganese ternary mixed salt solution with a total metal ion concentration of 1 to 2 mol / L, a sodium hydroxide solution with a mass concentration of 28 to 32 wt%, and an ammonia solution with a mass concentration of 10 to 20 wt% are added concurrently to a reaction base solution with a complexing agent concentration of 4 to 8 g / L and a pH of 10.0 to 12.0 to carry out a coprecipitation reaction. During the coprecipitation reaction, the pH of the reaction system is controlled to be 10.0 to 12.0, the ammonia concentration is 4 to 8 g / L, and the temperature is 40 to 60° C., until the D50 particle size of the precipitate reaches 3 to 4 μm; During the parallel addition process, the flow rate of adding the nickel-cobalt-manganese ternary mixed salt solution is 6 to 10 L / h, the flow rate of adding the precipitant solution is 2 to 3 L / h, and the flow rate of adding the complexing agent solution is 0.3 to 0.6 L / h; The second stage: stop adding the nickel-cobalt-manganese ternary mixed salt solution, the precipitant solution and the complexing agent solution, and continue the coprecipitation reaction until the materials in the reaction system react completely to obtain a high-nickel ternary precursor; (2) mixing the high-nickel ternary precursor obtained in step (1) with a lithium source, and performing a heat treatment at 400-600° C. for 250-350 min to obtain a high-nickel ternary positive electrode material; (3) depositing a lithium fluoride layer on the surface of the high-nickel ternary cathode material obtained in step (2) by magnetron sputtering, wherein the argon pressure during the magnetron sputtering process is 0.05 to 0.2 Pa, the sputtering power is 150 to 250 W, the temperature is 100 to 300° C., and the distance between the target and the substrate is 8 to 12 cm; Then, the temperature is raised to 160-240° C. at a rate of 1-10° C. / min, kept at this temperature for 10-20 minutes, and then lowered to 20-60° C. at a rate of 1-5° C. / min to obtain the positive electrode active material.

10. A battery, characterized in that: The battery comprises the positive electrode active material according to any one of claims 1 to 4.

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