Lithium nickel cobalt manganese oxide cathode material, preparation method thereof, cathode and lithium ion battery

Abstract

The application provides a lithium nickel cobalt manganese oxide positive electrode material, a preparation method thereof, a positive electrode and a lithium ion battery. x Co (1‑x‑y‑a) Mn y Zr a O (2‑2b) F b and a coating layer coated on the surface of LiNi x Co (1‑x‑y‑a) Mn y Zr a O (2‑2b) F b The coating layer comprises a phosphate, 0 The zirconium and fluorine elements doped in the lithium nickel cobalt manganese oxide positive electrode material can increase the crystal face spacing, thereby promoting the migration of lithium ions, improving the compaction density and cycle life of the lithium nickel cobalt manganese oxide positive electrode material, and improving the structural stability and safety of the lithium nickel cobalt manganese oxide positive electrode material. Therefore, the structural stability, cycle performance and thermal stability of the lithium nickel cobalt manganese oxide positive electrode material are further improved.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, and more specifically, to a lithium nickel cobalt manganese oxide cathode material, its preparation method, cathode, and lithium-ion battery. Background Technology

[0002] Lithium-ion batteries, as a green and environmentally friendly secondary energy storage device, have advantages such as being lightweight, portable, high-energy, and environmentally friendly. With the increasing demand for lithium batteries from communication base stations, audio-visual equipment, industrial instruments, medical devices, mobile phones, laptops, power tools, electric bicycles, and even electric vehicles, higher requirements are being placed on the comprehensive performance of batteries, such as energy density, cycle life, and safety performance.

[0003] In lithium-ion batteries, the cathode material is one of the most critical components, and its performance largely determines the battery's overall performance. Currently, with the market demanding increasingly higher energy density battery systems, the specific capacity of the cathode material has become one of the main limiting factors for the development of lithium-ion batteries. Therefore, developing high-specific-capacity lithium-ion battery cathode materials is of profound significance for the development and improvement of lithium-ion batteries.

[0004] Currently, the mainstream cathode materials for lithium-ion batteries include lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, and lithium nickel cobalt manganese oxide. Lithium nickel cobalt manganese oxide cathode materials, due to the synergistic effect of nickel, cobalt, and manganese, have advantages in overall performance, including energy density, cycle performance, safety performance, and cost, making them one of the most promising cathode materials. However, lithium nickel cobalt manganese oxide cathode materials face challenges such as rapid capacity decay under high voltage conditions, agglomeration and pulverization of particles, and poor structural stability, which limit their application under high voltage conditions. Summary of the Invention

[0005] The main objective of this invention is to provide a lithium nickel cobalt manganese oxide cathode material and its preparation method, as well as a cathode and a lithium-ion battery, to solve the problems of poor stability, rapid cycle decay, and particle pulverization in lithium-ion batteries that include lithium cobalt manganese oxide cathode materials under high voltage in the prior art.

[0006] To achieve the above objectives, according to one aspect of the present invention, a lithium nickel cobalt manganese oxide cathode material is provided, the lithium nickel cobalt manganese oxide cathode material comprising LiNi x Co (1-x-y-a) Mn y Zr a O (2-2b) F b and coated with LiNi x Co (1-x-y-a) Mn y Zr a O (2-2b) F bA coating layer on the surface, wherein the coating layer comprises phosphate, wherein 0 < x < 1, 0 < y < 1, 0 < a + x + y < 1, 0.0005 < a < 0.03, and 0.0005 < b < 0.03.

[0007] Furthermore, the aforementioned coating layer also includes aluminum isopropoxide, which is composited with phosphate to form the coating layer. Preferably, the coating layer consists of phosphate, aluminum isopropoxide, and LiNi. x Co (1-x-y-a) Mn y Zr a O (2-2b) F b The mass ratio is 0.0005–0.005:0.0005–0.005:1. Further, the mass ratio of phosphate to aluminum isopropoxide is preferably 0.005–0.05:0.005–0.05. Preferably, the phosphate is selected from any one or more of magnesium phosphate, zinc phosphate, and calcium phosphate. Preferably, the residual alkali content on the surface of the lithium nickel cobalt manganese oxide cathode material is 0.4–0.7%. Preferably, LiNi... x Co (1-x-y-a) Mn y Zr a O (2-2b) F b The particle size D50 is 3–6 μm.

[0008] According to another aspect of the present invention, a method for preparing the above-mentioned lithium nickel cobalt manganese oxide cathode material is provided. The method includes: step S1, mixing a first material comprising a nickel cobalt manganese precursor, a zirconium source, a fluorine source, and a lithium source to obtain a first mixture; step S2, sintering the first mixture in an oxygen-containing atmosphere to obtain a lithium nickel cobalt manganese oxide dopant; step S3, mixing the lithium nickel cobalt manganese oxide dopant with a second material comprising a phosphate to obtain a second mixture; and step S4, sintering the second mixture in an oxygen-containing atmosphere to obtain the lithium nickel cobalt manganese oxide cathode material.

[0009] Further, in step S3 above, the phosphate is dissolved in a solvent and added to the second material in the form of a solution. Preferably, the solvent is an aqueous solution of diammonium hydrogen phosphate, and the mass concentration of the aqueous solution of diammonium hydrogen phosphate is 10-30 wt%. Preferably, the second material also includes aluminum isopropoxide, and preferably the mass ratio of phosphate, aqueous solution of diammonium hydrogen phosphate, aluminum isopropoxide, and lithium nickel cobalt manganese oxide dopant is 0.005-0.05:0.003-0.06:0.005-0.05:1.

[0010] Further, the molar ratio of the above-mentioned nickel-cobalt-manganese precursor, zirconium source, fluorine source, and lithium source is 1:0.0005-0.003:0.0005-0.003:1.0-1.15. Preferably, the nickel-cobalt-manganese precursor is selected from any one or more of nickel-cobalt-manganese oxide, nickel-cobalt-manganese hydroxide, or nickel-cobalt-manganese carbonate; preferably, the zirconium source is selected from any one or more of zirconium oxide, zirconium acetate, and zirconium carbonate; preferably, the fluorine source is selected from any one or more of lithium fluoride, sodium fluoride, and potassium fluoride; preferably, the lithium source is selected from any one or more of lithium hydroxide, lithium carbonate, lithium nitrate, and lithium acetate.

[0011] Furthermore, the first mixture and the second mixture described above are each independently ball-milled mixtures, preferably with a ball-milling speed of 100 to 800 r / min and a ball-milling time of 1 to 6 h.

[0012] Furthermore, the temperature of the first sintering is 700 to 1100°C, the heating rate of the first sintering is preferably 1 to 10°C / min, and the time of the first sintering is preferably 5 to 30 hours.

[0013] Furthermore, the temperature of the second sintering is 600-900°C, the heating rate of the second sintering is preferably 1-10°C / min, and the time of the second sintering is preferably 5-20h.

[0014] According to another aspect of the present invention, a positive electrode is provided, comprising a positive electrode material, wherein the positive electrode material is the aforementioned lithium nickel cobalt manganese oxide positive electrode material or the lithium nickel cobalt manganese oxide positive electrode material obtained by the aforementioned preparation method, wherein the compaction density of the positive electrode is 3.6–3.8 g / cm³. 3 .

[0015] According to another aspect of the present invention, a lithium-ion battery is provided, comprising a positive electrode and a negative electrode, wherein the positive electrode is the aforementioned positive electrode.

[0016] By applying the technical solution of this invention, the zirconium and fluorine elements doped in the lithium nickel cobalt manganese oxide cathode material can increase the interplanar spacing, thereby promoting lithium-ion migration. Since fluorine (F) has a stronger electronegativity than oxygen (O), the chemical bonds formed between fluorine and metal ions within the lithium nickel cobalt manganese oxide cathode material are more robust, thus improving its compaction density and cycle life. Furthermore, it can enhance the structural stability and safety of the lithium nickel cobalt manganese oxide cathode material. The phosphate coating layer further prevents contact between the electrolyte and the surface of the lithium nickel cobalt manganese oxide cathode material, suppressing surface side reactions and inhibiting the corrosive effect of the electrolyte, thereby further improving the structural stability, cycle performance, and thermal stability of the lithium nickel cobalt manganese oxide cathode material. Attached Figure Description

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0018] Figure 1 A scanning electron microscope image of a lithium nickel cobalt manganese oxide cathode material according to Embodiment 1 of the present invention is shown;

[0019] Figure 2 A scanning electron microscope image of a lithium nickel cobalt manganese oxide cathode material according to Embodiment 10 of the present invention is shown;

[0020] Figure 3 A scanning electron microscope (SEM) image of a lithium nickel cobalt manganese oxide cathode material according to Comparative Example 1 of the present invention is shown; and

[0021] Figure 4 A graph showing the cycle capacity retention of a lithium-ion battery made of a lithium nickel cobalt manganese oxide cathode material according to Embodiment 1 of the present invention is shown. Detailed Implementation

[0022] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] As analyzed in the background section of this application, existing lithium-ion batteries suffer from problems such as poor stability, rapid cycle decay, and particle pulverization under high voltage. To address these issues, this application provides a lithium nickel cobalt manganese oxide cathode material, its preparation method, the cathode material, and a lithium-ion battery.

[0024] In a typical embodiment of this application, a lithium nickel cobalt manganese oxide cathode material is provided, which includes LiNi x Co (1-x-y-a) Mn y Zr a O (2-2b) F b and coated with LiNi x Co (1-x-y-a) Mn y Zr a O (2-2b) F b A coating layer on the surface, wherein the coating layer comprises phosphate, wherein 0 < x < 1, 0 < y < 1, 0 < a + x + y < 1, 0.0005 < a < 0.03, and 0.0005 < b < 0.03.

[0025] The zirconium and fluorine doping in the lithium nickel cobalt manganese oxide cathode material of this invention increases the interplanar spacing, thereby promoting lithium-ion migration. Since fluorine (F) has a stronger electronegativity than oxygen (O), the chemical bonds formed between fluorine and metal ions within the lithium nickel cobalt manganese oxide cathode material are more robust, thus improving its compaction density and cycle life. Furthermore, it enhances the structural stability and safety of the lithium nickel cobalt manganese oxide cathode material. The phosphate coating layer further prevents contact between the electrolyte and the surface of the lithium nickel cobalt manganese oxide cathode material, suppressing surface side reactions and inhibiting electrolyte corrosion, thereby further improving the structural stability, cycle performance, and thermal stability of the lithium nickel cobalt manganese oxide cathode material.

[0026] In one embodiment of this application, the coating layer further includes aluminum isopropoxide, which is composited with phosphate to form the coating layer. Preferably, the coating layer consists of phosphate, aluminum isopropoxide, and LiNi. x Co (1-x-y-a) Mn y Zr a O (2-2b) F b The mass ratio is 0.005–0.05:0.0005–0.005:1. Further, the mass ratio of phosphate to aluminum isopropoxide is preferably 0.005–0.05:0.005–0.05. Preferably, the phosphate is selected from any one or more of magnesium phosphate, zinc phosphate, and calcium phosphate. Preferably, the residual alkali content on the surface of the lithium nickel cobalt manganese oxide cathode material is 0.4–0.7%. Preferably, LiNi... x Co (1-x-y-a) Mn y Zr a O (2-2b) F b The particle size D50 is 3–6 μm.

[0027] The coating of lithium nickel cobalt manganese oxide (LCO) cathode material with aluminum isopropoxide isolates the active material from the electrolyte, preventing cobalt leaching and loss. This also enhances the electrochemical stability of the LCO cathode material under high voltage and improves its cycle performance. Therefore, the co-coating of phosphate and aluminum isopropoxide improves both the electrochemical stability and cycle performance of the LCO cathode material under high voltage. The preferred mass ratio of phosphate to aluminum isopropoxide further promotes synergistic effects, resulting in superior overall performance of the final LCO cathode material. Simultaneously, aluminum isopropoxide can react with residual alkali (LiOH or Li₂CO₃) on the surface of the LCO cathode material to form a lithium-ion conductor, lithium aluminum oxide, which possesses a certain lithium-ion conductivity. Therefore, it can further improve the cycle stability and processability of the LCO cathode material while reducing residual alkali on its surface.

[0028] In a typical embodiment of this application, a method for preparing the aforementioned lithium nickel cobalt manganese oxide cathode material is provided. The method includes: step S1, mixing a first material comprising a nickel cobalt manganese precursor, a zirconium source, a fluorine source, and a lithium source to obtain a first mixture; step S2, sintering the first mixture in an oxygen-containing atmosphere to obtain a lithium nickel cobalt manganese oxide dopant; step S3, mixing the lithium nickel cobalt manganese oxide dopant with a second material comprising phosphate to obtain a second mixture; and step S4, sintering the second mixture in an oxygen-containing atmosphere to obtain the lithium nickel cobalt manganese oxide cathode material.

[0029] The zirconium and fluorine elements doped in the lithium nickel cobalt manganese oxide cathode material obtained through steps S1 and S2 of the above preparation method ensure the uniform distribution of dopant ions in the lithium nickel cobalt manganese oxide cathode material. The zirconium and fluorine doping increases the interplanar spacing, thereby promoting lithium ion migration. Since fluorine (F) has a stronger electronegativity than oxygen (O), the chemical bonds formed between fluorine and metal ions in the lithium nickel cobalt manganese oxide cathode material are more robust, thus improving its compaction density and cycle life, and enhancing the structural stability and safety of the lithium nickel cobalt manganese oxide cathode material. Steps S3 and S4 yield a phosphate-coated lithium nickel cobalt manganese oxide cathode material, thus avoiding direct contact between the electrolyte and the surface of the lithium nickel cobalt manganese oxide cathode material, suppressing surface side reactions, and inhibiting the corrosive effect of the electrolyte, thereby further improving the structural stability, cycle performance, and thermal stability of the lithium nickel cobalt manganese oxide cathode material.

[0030] In one embodiment of this application, in step S3 above, the phosphate is dissolved in a solvent and added to the second material in the form of a solution. Preferably, the solvent is an aqueous solution of diammonium hydrogen phosphate, and the mass concentration of the aqueous solution of diammonium hydrogen phosphate is 10-30 wt%. Preferably, the second material also includes aluminum isopropoxide. Preferably, the mass ratio of phosphate, aqueous solution of diammonium hydrogen phosphate, aluminum isopropoxide, and lithium nickel cobalt manganese oxide dopant is 0.005-0.05:0.003-0.06:0.005-0.05:1.

[0031] The aluminum isopropoxide coating of the lithium nickel cobalt manganese oxide (LCO) cathode material isolates the active material from the electrolyte, preventing cobalt leaching and loss. The phosphate avoids direct contact between the electrolyte and the surface of the LCO cathode material, suppressing surface side reactions and inhibiting electrolyte corrosion. The preferred mass ratio allows for better synergistic effects between the phosphate and aluminum isopropoxide, thereby improving the structural stability, cycle performance, and thermal stability of the LCO cathode material.

[0032] Phosphate has excellent solubility in aqueous diammonium hydrogen phosphate solution. The above-mentioned mass ratio of phosphate to aqueous diammonium hydrogen phosphate solution is preferred for wet coating, which not only makes the coating of phosphate more uniform, but also avoids the introduction of other unnecessary impurities.

[0033] Preferably, the molar ratio of the above-mentioned nickel-cobalt-manganese precursor, zirconium source, fluorine source, and lithium source is 1:0.0005-0.003:0.0005-0.003:1.0-1.15. Preferably, the nickel-cobalt-manganese precursor is selected from any one or more of nickel-cobalt-manganese oxide, nickel-cobalt-manganese hydroxide, or nickel-cobalt-manganese carbonate; preferably, the zirconium source is selected from any one or more of zirconium oxide, zirconium acetate, and zirconium carbonate; preferably, the fluorine source is selected from any one or more of lithium fluoride, sodium fluoride, and potassium fluoride; preferably, the lithium source is selected from any one or more of lithium hydroxide, lithium carbonate, lithium nitrate, and lithium acetate. This facilitates the synergistic effect between the elements to achieve a high-performance lithium nickel-cobalt-manganese oxide cathode material.

[0034] Preferably, the first and second mixtures are each independently ball-milled, with a ball-milling speed of 100–800 r / min and a ball-milling time of 1–6 h. This helps to achieve uniform mixing between the raw material components, resulting in a better performance of the obtained lithium nickel cobalt manganese oxide cathode material.

[0035] Preferably, the temperature of the first sintering is 700-1100℃, the heating rate of the first sintering is 1-10℃ / min, and the time of the first sintering is 5-30h, which helps to improve the structural stability of the lithium nickel cobalt manganese oxide cathode material and allows zirconium and fluorine elements to be uniformly doped into it.

[0036] Preferably, the second sintering temperature is 600-900°C, the second sintering heating rate is 1-10°C / min, and the second sintering time is 5-20h, which helps to uniformly and firmly coat the surface of the lithium nickel cobalt manganese oxide cathode material with phosphates.

[0037] In another typical embodiment of this application, a positive electrode is provided, comprising a positive electrode material, which is the aforementioned lithium nickel cobalt manganese oxide positive electrode material or the lithium nickel cobalt manganese oxide positive electrode material obtained by the aforementioned preparation method, wherein the compaction density of the positive electrode is 3.6–3.8 g / cm³. 3 .

[0038] The cathode materials, including the aforementioned lithium nickel cobalt manganese oxide cathode materials, exhibit excellent structural stability, cycle performance, and thermal stability.

[0039] In another typical embodiment of this application, a lithium-ion battery is provided, including a positive electrode and a negative electrode, wherein the positive electrode is the aforementioned positive electrode.

[0040] Lithium-ion batteries, including the aforementioned cathode, exhibit excellent structural stability, cycle performance, and thermal stability.

[0041] The beneficial effects of this application will be further illustrated below with reference to the embodiments.

[0042] Example 1

[0043] Weigh Ni in a molar ratio of 1:0.0004:0.0025:1.05. 0.5 Co 0.2 Mn 0.3 (OH)2, Zr2O3, LiF and Li2CO3 were placed in a ball mill and ball-milled at 300 r / min for 3 h to obtain the first mixture.

[0044] The first mixture was placed in a muffle furnace and heated to 940°C at a heating rate of 5°C / min, and calcined for 10 hours in an oxygen atmosphere. It was then naturally cooled to room temperature, ground, crushed, and sieved to prepare lithium nickel cobalt manganese oxide doped material with the chemical formula LiNi. 0.5 Co 0.1992 Mn 0.3 Zr 0.0008 O 1.995 F 0.0025 .

[0045] Magnesium phosphate, diammonium hydrogen phosphate aqueous solution, aluminum isopropoxide, and lithium nickel cobalt manganese oxide dopant were mixed in a mass ratio of 0.006:0.003:0.006:1. After uniform mixing, the mixture was dried at 150°C. The dried material was then ball-milled again at 300 r / min for 3 h to obtain a second mixture, wherein the mass fraction of diammonium hydrogen phosphate in the diammonium hydrogen phosphate aqueous solution was 30 wt%.

[0046] The second mixture was placed in a muffle furnace and heated from room temperature to 880°C at a heating rate of 5°C / min. It was calcined for 15 hours under an oxygen atmosphere, and after natural cooling to room temperature, it was ground, crushed, and sieved to prepare lithium nickel cobalt manganese oxide cathode material. Its scanning electron microscope image is shown below. Figure 1 As shown, from Figure 1 It can be seen that the lithium nickel cobalt manganese oxide cathode material has a uniform morphology and a smooth surface.

[0047] Example 2

[0048] Weigh Ni in a molar ratio of 1:0.001:0.0025:1.0 0.5 Co 0.2 Mn 0.3 (OH)2, Zr2O3, LiF and Li2CO3 were placed in a ball mill and ball-milled at 300 r / min for 3 h to obtain the first mixture.

[0049] The first mixture was placed in a muffle furnace and heated to 940°C at a heating rate of 5°C / min, and calcined for 10 hours in an oxygen atmosphere. It was then naturally cooled to room temperature, ground, crushed, and sieved to prepare lithium nickel cobalt manganese oxide doped material with the chemical formula LiNi. 0.5 Co 0.198 Mn0.3 Zr 0.002 O 1.995 F 0.0025 .

[0050] Magnesium phosphate, diammonium hydrogen phosphate aqueous solution, aluminum isopropoxide, and lithium nickel cobalt manganese oxide dopant were mixed in a mass ratio of 0.006:0.003:0.006:1. After uniform mixing, the mixture was dried at 150°C. The dried material was then ball-milled again at 300 r / min for 3 h to obtain a second mixture, wherein the mass fraction of diammonium hydrogen phosphate in the diammonium hydrogen phosphate aqueous solution was 30 wt%.

[0051] The second mixture was placed in a muffle furnace and heated from room temperature to 880°C at a heating rate of 5°C / min. It was calcined for 15 hours in an oxygen atmosphere and then naturally cooled to room temperature. The mixture was then ground, crushed, and sieved to prepare lithium nickel cobalt manganese oxide cathode material.

[0052] Example 3

[0053] Weigh Ni in a molar ratio of 1:0.001:0.0025:1.12. 0.5 Co 0.2 Mn 0.3 CO3, Zr2O3, LiF, and LiOH·H2O were placed in a ball mill and ball-milled at 300 r / min for 3 h to obtain the first mixture.

[0054] The first mixture was placed in a muffle furnace and heated to 940°C at a heating rate of 5°C / min, and calcined for 10 hours in an oxygen atmosphere. It was then naturally cooled to room temperature, ground, crushed, and sieved to prepare lithium nickel cobalt manganese oxide doped material with the chemical formula LiNi. 0.5 Co 0.198 Mn 0.3 Zr 0.002 O 1.995 F 0.0025 .

[0055] Magnesium phosphate, diammonium hydrogen phosphate aqueous solution, aluminum isopropoxide, and lithium nickel cobalt manganese oxide dopant were mixed in a mass ratio of 0.006:0.003:0.006:1. After uniform mixing, the mixture was dried at 150°C. The dried material was then ball-milled again at 300 r / min for 3 h to obtain a second mixture, wherein the mass fraction of diammonium hydrogen phosphate in the diammonium hydrogen phosphate aqueous solution was 30 wt%.

[0056] The second mixture was placed in a muffle furnace and heated from room temperature to 880°C at a heating rate of 5°C / min. It was calcined for 15 hours in an oxygen atmosphere and then naturally cooled to room temperature. The mixture was then ground, crushed, and sieved to prepare lithium nickel cobalt manganese oxide cathode material.

[0057] Example 4

[0058] Weigh Ni in a molar ratio of 1:0.0004:0.0025:1.05. 0.5 Co 0.2 Mn 0.3 (OH)2, Zr2O3, LiF and Li2CO3 were placed in a ball mill and ball-milled at 300 r / min for 3 h to obtain the first mixture.

[0059] The first mixture was placed in a muffle furnace and heated to 940°C at a heating rate of 5°C / min, and calcined for 10 hours under an oxygen atmosphere. It was then naturally cooled to room temperature, ground, crushed, and sieved to prepare lithium nickel cobalt manganese oxide cathode material with the chemical formula LiNi. 0.5 Co 0.1992 Mn 0.3 Zr 0.0008 O 1.995 F 0.0025 .

[0060] Magnesium phosphate, diammonium hydrogen phosphate aqueous solution, and lithium nickel cobalt manganese oxide dopant were mixed at a mass ratio of 0.006:0.003:1. After being mixed evenly, the mixture was dried at 150°C. The dried material was then ball-milled again to obtain a second mixture, wherein the mass fraction of diammonium hydrogen phosphate in the diammonium hydrogen phosphate aqueous solution was 30 wt%.

[0061] The second mixture was placed in a muffle furnace and heated from room temperature to 880°C at a heating rate of 5°C / min. It was calcined for 15 hours in an oxygen atmosphere and then naturally cooled to room temperature. The mixture was then ground, crushed, and sieved to prepare lithium nickel cobalt manganese oxide cathode material.

[0062] Example 5

[0063] The difference from Example 1 is that the mass ratio of magnesium phosphate, diammonium hydrogen phosphate aqueous solution, aluminum isopropoxide, and lithium nickel cobalt manganese oxide dopant is 0.01:0.03:0.01:1, and the final product is lithium nickel cobalt manganese oxide cathode material.

[0064] Example 6

[0065] The difference from Example 1 is that the mass ratio of magnesium phosphate, diammonium hydrogen phosphate aqueous solution, aluminum isopropoxide, and lithium nickel cobalt manganese oxide dopant is 0.05:0.06:0.05:1, and the final product is lithium nickel cobalt manganese oxide cathode material.

[0066] Example 7

[0067] The difference from Example 1 is that the mass ratio of magnesium phosphate, diammonium hydrogen phosphate aqueous solution, aluminum isopropoxide, and lithium nickel cobalt manganese oxide dopant is 0.003:0.002:0.003:1, and the lithium nickel cobalt manganese oxide cathode material is finally obtained.

[0068] Example 8

[0069] The difference from Example 1 is that the second sintering temperature is 600°C, and the lithium nickel cobalt manganese oxide cathode material is finally obtained.

[0070] Example 9

[0071] The difference from Example 1 is that the second sintering temperature is 900°C, and lithium nickel cobalt manganese oxide cathode material is finally obtained.

[0072] Example 10

[0073] The difference from Example 1 is that the first sintering temperature was 910°C, ultimately yielding a lithium nickel cobalt manganese oxide cathode material, the scanning electron microscope image of which is shown below. Figure 2 As shown.

[0074] Example 11

[0075] The difference from Example 1 is that the first sintering temperature is 700°C, and the final product is lithium nickel cobalt manganese oxide cathode material.

[0076] Example 12

[0077] The difference from Example 1 is that the first sintering temperature is 1100℃, and the final product is lithium nickel cobalt manganese oxide cathode material.

[0078] Example 13

[0079] The difference from Example 1 is that the second sintering temperature is 650°C, and the final product is lithium nickel cobalt manganese oxide cathode material.

[0080] Example 14

[0081] The difference from Example 1 is that the heating rate of the first sintering is 10℃ / min and the first sintering time is 30h, the heating rate of the second sintering is 10℃ / min and the second sintering time is 20h, and finally lithium nickel cobalt manganese oxide cathode material is obtained.

[0082] Example 15

[0083] The difference from Example 1 is that the ball milling speed for both the first and second mixtures is 800 r / min, and the ball milling time is 6 h, ultimately yielding lithium nickel cobalt manganese oxide cathode material.

[0084] Example 16

[0085] The difference from Example 1 is that Ni was weighed in a molar ratio of 1:0.003:0.0015:1.05. 0.5 Co 0.2 Mn 0.3(OH)2, Zr2O3, LiF and Li2CO3 were placed in a ball mill and ball-milled at 300 r / min for 3 h to obtain the first mixture, and finally the lithium nickel cobalt manganese oxide cathode material was obtained.

[0086] Comparative Example 1

[0087] Weigh Ni in a molar ratio of 1:1.05. 0.5 Co 0.2 Mn 0.3 (OH)2 and Li2CO3 were placed in a ball mill and ball-milled at 300 r / min for 3 h to obtain the first mixture.

[0088] The first mixture was placed in a muffle furnace and heated to 940°C at a heating rate of 5°C / min, and calcined for 10 hours in an oxygen atmosphere. It was then naturally cooled to room temperature, ground, crushed, and sieved to prepare lithium nickel cobalt manganese oxide material with the chemical formula LiNi. 0.5 Co 0.2 Mn 0.3 O2.

[0089] Lithium nickel cobalt manganese oxide dopant was placed in a muffle furnace and heated from room temperature to 880°C at a heating rate of 5°C / min. Calcination was carried out for 15 hours in an oxygen atmosphere. After natural cooling to room temperature, the material was ground, crushed, and sieved to obtain the lithium nickel cobalt manganese oxide cathode material. Its scanning electron microscope image is shown below. Figure 3 As shown.

[0090] Comparative Example 2

[0091] Weigh Ni in a molar ratio of 1:0.0004:0.0025:1.05. 0.5 Co 0.2 Mn 0.3 (OH)2, Zr2O3, LiF and Li2CO3 were placed in a ball mill and ball-milled at 300 r / min for 3 h to obtain the first mixture.

[0092] The first mixture was placed in a muffle furnace and heated to 940°C at a heating rate of 5°C / min, and calcined for 10 hours under an oxygen atmosphere. It was then naturally cooled to room temperature, ground, crushed, and sieved to prepare lithium nickel cobalt manganese oxide cathode material with the chemical formula LiNi. 0.5 Co 0.1992 Mn 0.3 Zr 0.0008 O 1.995 F 0.0025 .

[0093] Comparative Example 3

[0094] Weigh Ni in a molar ratio of 1:0.0004:0.0025:1.05. 0.5 Co 0.2 Mn0.3 (OH)2, Zr2O3, LiF and Li2CO3 were placed in a ball mill and ball-milled at 300 r / min for 3 h to obtain the first mixture.

[0095] The first mixture was placed in a muffle furnace and heated to 940°C at a heating rate of 5°C / min, and calcined for 10 hours under an oxygen atmosphere. It was then naturally cooled to room temperature, ground, crushed, and sieved to prepare lithium nickel cobalt manganese oxide cathode material with the chemical formula LiNi. 0.5 Co 0.1992 Mn 0.3 Zr 0.0008 O 1.995 F 0.0025 .

[0096] Aluminum isopropoxide and lithium nickel cobalt manganese oxide dopants were mixed at a mass ratio of 0.015:1. After being mixed evenly, the mixture was dried at 150°C. The dried material was then ball-milled again to obtain a second mixture, wherein the mass fraction of diammonium hydrogen phosphate in the diammonium hydrogen phosphate aqueous solution was 30 wt%.

[0097] The second mixture was placed in a muffle furnace and heated from room temperature to 880°C at a heating rate of 5°C / min. It was calcined for 15 hours in an oxygen atmosphere and then naturally cooled to room temperature. The mixture was then ground, crushed, and sieved to prepare lithium nickel cobalt manganese oxide cathode material.

[0098] The residual alkali of the lithium nickel cobalt manganese oxide cathode materials obtained in Examples 1 to 16 and Comparative Examples 1 to 3 was tested, as well as the compaction density of the corresponding cathode sheets. A 2Ah soft-pack lithium-ion battery was prepared using the lithium nickel cobalt manganese oxide cathode materials obtained in Examples 1 to 16 and Comparative Examples 1 to 3. The initial discharge capacity and initial charge-discharge efficiency were tested at 0.2C. The capacity retention rate after 300 cycles was tested under 4.4V and 1C charge-discharge conditions. The test results are listed in Table 1. Figure 4 The graph shows the cycle capacity retention rate of the lithium-ion battery corresponding to Example 1.

[0099] Table 1

[0100]

[0101] As shown in Table 1, the doping of zirconium and fluorine elements during the synthesis of lithium nickel cobalt manganese oxide (LCO) followed by surface coating with phosphate and aluminum isopropoxide significantly reduces residual lithium on the material surface and improves the compaction density of the battery electrode. The soft-pack lithium-ion battery made with this material retains over 90% of its capacity after 300 cycles at 4.4V and 1C, exhibiting superior cycle performance compared to Comparative Examples 1, 2, and 3, demonstrating a significant improvement in cycle performance. Therefore, the LCO prepared by this invention, when applied to lithium-ion batteries, not only improves battery energy density but also significantly enhances cycle life and safety. It can be used alone or blended with lithium cobalt oxide or lithium manganese oxide, making it suitable for a wide range of applications.

[0102] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0103] The zirconium and fluorine doping in the lithium nickel cobalt manganese oxide cathode material of this invention increases the interplanar spacing, thereby promoting lithium-ion migration. Since fluorine (F) has a stronger electronegativity than oxygen (O), the chemical bonds formed between fluorine and metal ions within the lithium nickel cobalt manganese oxide cathode material are more robust, thus improving its compaction density and cycle life. Furthermore, it enhances the structural stability and safety of the lithium nickel cobalt manganese oxide cathode material. The phosphate coating layer further prevents contact between the electrolyte and the surface of the lithium nickel cobalt manganese oxide cathode material, suppressing surface side reactions and inhibiting electrolyte corrosion, thereby further improving the structural stability, cycle performance, and thermal stability of the lithium nickel cobalt manganese oxide cathode material.

[0104] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A lithium nickel cobalt manganese oxide cathode material, characterized in that, The lithium nickel cobalt manganese oxide cathode material includes LiNi x Co (1-x-y-a) Mn y Zr a O (2-2b) F b and coated with the LiNi x Co (1-x-y-a) Mn y Zr a O (2-2b) F b A coating layer on the surface, wherein the coating layer comprises phosphate, wherein 0 < x < 1, 0 < y < 1, 0 < a + x + y < 1, 0.0005 < a < 0.03, 0.0005 < b < 0.03; The coating layer further includes aluminum isopropoxide, which is compounded with the phosphate to form the coating layer. The phosphate, aluminum isopropoxide, and LiNi x Co (1-x-y-a) Mn y Zr a O (2-2b) F b The mass ratio is 0.0005~0.005:0.0005~0.005:1; The phosphate is selected from any one or more of magnesium phosphate, zinc phosphate, and calcium phosphate.

2. The lithium nickel cobalt manganese oxide cathode material according to claim 1, characterized in that, The mass ratio of the phosphate to the aluminum isopropoxide is 0.005~0.05:0.005~0.

05.

3. The lithium nickel cobalt manganese oxide cathode material according to claim 1, characterized in that, The LiNi x Co (1-x-y-a) Mn y Zr a O (2-2b) F b The particle size D50 is 3~6μm.

4. A method for preparing the lithium nickel cobalt manganese oxide cathode material according to any one of claims 1 to 3, characterized in that, The preparation method includes: Step S1: The first material, including nickel-cobalt-manganese precursor, zirconium source, fluorine source and lithium source, is first mixed to obtain a first mixture; Step S2: In an oxygen-containing atmosphere, the first mixture is subjected to a first sintering to obtain lithium nickel cobalt manganese oxide doped material; Step S3: The second material, including the lithium nickel cobalt manganese oxide dopant and phosphate, is mixed a second time to obtain a second mixture; Step S4: In an oxygen-containing atmosphere, the second mixture is subjected to a second sintering to obtain the lithium nickel cobalt manganese oxide cathode material; In step S3, the phosphate is dissolved in a solvent and added to the second material in the form of a solution, wherein the solvent is an aqueous solution of diammonium hydrogen phosphate; The second material also includes aluminum isopropoxide, and the mass ratio of the phosphate, the aqueous solution of diammonium hydrogen phosphate, the aluminum isopropoxide, and the lithium nickel cobalt manganese oxide dopant is 0.005~0.05:0.003~0.06:0.005~0.05:

1.

5. The preparation method according to claim 4, characterized in that, The mass concentration of the diammonium hydrogen phosphate aqueous solution is 10~30wt%.

6. The preparation method according to claim 4 or 5, characterized in that, The molar ratio of the nickel-cobalt-manganese precursor, the zirconium source, the fluorine source, and the lithium source is 1:0.0005~0.003:0.0005~0.003:1.0~1.

15.

7. The preparation method according to claim 4 or 5, characterized in that, The nickel-cobalt-manganese precursor is selected from any one or more of nickel-cobalt-manganese oxide, nickel-cobalt-manganese hydroxide, or nickel-cobalt-manganese carbonate; the zirconium source is selected from any one or more of zirconium oxide, zirconium acetate, and zirconium carbonate; the fluorine source is selected from any one or more of lithium fluoride, sodium fluoride, and potassium fluoride; and the lithium source is selected from any one or more of lithium hydroxide, lithium carbonate, lithium nitrate, and lithium acetate.

8. The preparation method according to claim 4 or 5, characterized in that, The first mixture and the second mixture are each independently ball-milled mixtures.

9. The preparation method according to claim 8, characterized in that, The ball milling speed is 100~800 r / min, and the ball milling time is 1~6 h.

10. The preparation method according to claim 4 or 5, characterized in that, The first sintering temperature is 700~1100℃, the first sintering heating rate is 1~10℃ / min, and the first sintering time is 5~30h.

11. The preparation method according to claim 4 or 5, characterized in that, The second sintering temperature is 600~900℃, the second sintering heating rate is 1~10℃ / min, and the second sintering time is 5~20h.

12. A positive electrode, comprising a positive electrode material, characterized in that, The cathode material is the lithium nickel cobalt manganese oxide cathode material according to any one of claims 1 to 3 or the lithium nickel cobalt manganese oxide cathode material obtained by the preparation method according to any one of claims 4 to 11, wherein the compaction density of the cathode is 3.6~3.8 g / cm³. 3 .

13. A lithium-ion battery, comprising a positive electrode and a negative electrode, characterized in that, The positive electrode is the positive electrode according to claim 12.

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