CN111200120B - Ternary cathode material, preparation method thereof and lithium ion battery - Google Patents

Ternary cathode material, preparation method thereof and lithium ion battery Download PDF

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CN111200120B
CN111200120B CN201811384733.4A CN201811384733A CN111200120B CN 111200120 B CN111200120 B CN 111200120B CN 201811384733 A CN201811384733 A CN 201811384733A CN 111200120 B CN111200120 B CN 111200120B
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cobalt
ternary
cobalt borate
nickel ternary
cathode material
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CN111200120A (en
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严武渭
温伟城
杨顺毅
黄友元
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BTR Nano Tech Co Ltd
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    • H01M4/36Selection of substances as active materials, active masses, active liquids
    • H01M4/48Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
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    • H01M4/50Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
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    • H01M4/525Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
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Abstract

The invention provides a ternary cathode material, a preparation method thereof and a lithium ion battery. The ternary cathode material mainly comprises a high-nickel ternary material core and a cobalt borate coating layer. The preparation method comprises the following steps: 1) mixing a boron source and a cobalt source, and sintering in a protective atmosphere to obtain cobalt borate; 2) mixing the cobalt borate with the high-nickel ternary material, and heating in an oxidizing atmosphere to obtain the ternary cathode material. The ternary cathode material provided by the invention has the advantages that the high-nickel ternary material core, the cobalt borate coating layer and the lithium cobalt borate positioned between the high-nickel ternary material core and the cobalt borate coating layer are matched with each other, so that the ternary cathode material is low in residual alkali content and good in rate discharge capacity and cycle performance. The preparation method provided by the invention has the advantages of short flow, simple operation and easy industrialized mass production.

Description

Ternary cathode material, preparation method thereof and lithium ion battery
Technical Field
The invention belongs to the technical field of energy storage materials, relates to a ternary cathode material, and particularly relates to a ternary cathode material, a preparation method thereof and a lithium ion battery.
Background
Lithium ion batteries are widely used in consumer electronics, energy storage, electric vehicles and other applications, especially the demand for high energy density is continuously increased due to the increase of the endurance mileage of the electric vehicles at present, and the energy density of the lithium ion batteries is restricted by the capacity of the positive electrode material compared with the higher capacity (not less than 350mAh/g) of a graphite negative electrode system, so that the development of the positive electrode material with higher energy density is needed. High-nickel ternary cathode material Li z Ni 1-x-y Co x M y O 2 (0.95≤z≤1.10,0≤x≤0.20,0≤y≤0.20, M is one or more of Mn, Al, Mg, Ti and Nb), has higher discharge capacity (more than or equal to 180mAh/g) and voltage platform (3.8V), and becomes one of the most competitive anode materials at present. However, the high nickel ternary positive electrode material suffers from a problem of difficult processing caused by a high residual alkali (lithium hydroxide, lithium carbonate, etc.), and a disadvantage of poor high temperature cycle.
However, high nickel ternary positive electrode materials face high residual alkali (lithium hydroxide, lithium carbonate, lithium bicarbonate, etc.) yielding Ni 3+ Reduction to Ni 2+ And the generated active oxygen free radicals react with moisture and carbon dioxide in air with high humidity to intensify the rise of residual alkali. The alkaline substance can cause the C-F bond on the PVDF to be separated from HF to generate gel, and the battery generates carbon dioxide and water under high voltage, so that the defects of reduced coulombic efficiency, battery expansion and poor high-temperature cycle are caused. Residual alkali is a poor conductor of electrons and ions, which reduces the capacity and coulombic efficiency of the battery. In addition, the high-nickel ternary cathode material reacts with electrolyte during circulation or high-temperature storage, so that transition metal atoms are dissolved, the structure is changed, and particles are crushed, so that the circulation performance is deteriorated and the safety performance is reduced. Therefore, for the realization of the industrial application of the high nickel ternary material, the surface residual alkali must be reduced and the electrochemical performance and safety performance must be improved.
CN105789625A discloses LiCoBO 3 The preparation method is characterized in that lithium hydroxide, lithium carbonate, cobalt oxide or cobalt carbonate are dispersed in absolute ethyl alcohol, mixed and ball-milled, sintered in inert atmosphere after being dried, and cooled along with the furnace; then mixing with boric acid in absolute ethyl alcohol, ball milling, drying, and sintering in inert atmosphere to obtain LiCoBO 3 And (3) a positive electrode material. However, the rate capability and cycle performance of the cathode material obtained by the method are still to be improved.
CN107482204A discloses a metal solid solution modified high-nickel ternary cathode material and a preparation method thereof, wherein the material is of a core-shell structure and sequentially comprises a high-nickel ternary cathode material substrate, a transition layer and a coating layer from inside to outside, the coating layer comprises a metal lithium salt and one or more solid solution cathode active substances generated by the reaction of heterogeneous metal precursors and the high-nickel ternary cathode material precursors, and the transition layer is a heterogeneous metal element doped high-nickel ternary cathode material. Although the rate capability and the specific capacity are relatively good, the preparation method is extremely complicated, the product structure is complex, and the cost is high.
CN108063223A discloses a preparation method of a modified high-nickel ternary cathode material, which comprises the following steps: and mixing the washed high-nickel ternary cathode material with a metal salt solution for reaction, and drying and sintering the mixture in sequence to obtain the modified high-nickel ternary cathode material. Although the method can reduce free lithium and pH value on the surface of the high-nickel ternary material to a certain extent, the rate capability and cycle performance of the method are still to be improved.
Therefore, the development of a high-nickel ternary cathode material which is simple in preparation method, has better rate capability and cycle performance and can solve the problem of residual alkali is of great significance to the field.
Disclosure of Invention
In view of the above problems in the prior art, the present invention aims to provide a ternary cathode material, a preparation method thereof, and a lithium ion battery. The ternary cathode material provided by the invention has the advantages of high rate capacity, excellent cycle performance, low residual alkali and good industrial application prospect.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the invention provides a ternary cathode material, which mainly comprises a high-nickel ternary material core and a cobalt borate coating layer.
The ternary cathode material provided by the invention improves the discharge capacity, rate capacity and cycle performance of the ternary cathode material through the interaction of the high-nickel ternary material core and the cobalt borate coating layer, and reduces the residual alkali amount on the surface of the high-nickel ternary material core.
In the invention, the cobalt borate coating layer is positioned at the outermost side of the ternary cathode material.
In the invention, the high-nickel ternary material is a ternary material with the Ni content of more than or equal to 60 mol% in metal elements except Li.
Besides the high-nickel ternary material core and the cobalt borate coating layer, the ternary cathode material provided by the invention can also comprise other components or structures.
The following is a preferred technical solution of the present invention, but not a limitation to the technical solution provided by the present invention, and the technical objects and advantageous effects of the present invention can be better achieved and achieved by the following preferred technical solution.
In a preferred embodiment of the present invention, the cobalt borate coating layer is Co 2 B 2 O 5 And (4) coating.
Preferably, the thickness of the cobalt borate coating is 2 to 50nm, such as 2nm, 4nm, 8nm, 10nm, 14nm, 18nm or 20nm, but not limited to the recited values, and other values not recited within the range of values are equally applicable, preferably 5 to 20 nm.
Preferably, the mass ratio of the cobalt borate cladding layer to the high nickel ternary material core is (0.001-0.01):1, such as 0.001:1, 0.003:1, 0.005:1, 0.007:1, 0.009:1 or 0.01:1, but not limited to the recited values, and other values not recited in this numerical range are equally applicable, preferably (0.001-0.005): 1. In the invention, if the mass ratio of the cobalt borate coating layer to the high-nickel ternary material core is less than 0.001:1, the coating effect is ineffective, and if the mass ratio of the cobalt borate coating layer to the high-nickel ternary material core is more than 0.005:1, the coating layer is too thick and uneven, the lithium ion migration is blocked, and the multiplying power and the cycling behavior are reduced.
As a preferable technical solution of the present invention, the ternary cathode material further comprises lithium cobalt borate (LiCoBO) between the high nickel ternary material core and the cobalt borate coating layer 3 ). In the invention, the existence of the lithium cobalt borate can reduce the residual lithium hydroxide and lithium carbonate, thereby reducing the residual alkali amount. In addition, the lithium cobalt borate has electrochemical activity, the theoretical specific capacity is 215mAh/g, the voltage platform is 4.09V, and the lithium cobalt borate is an ion and electron conductor, so that the discharge capacity, the rate capacity and the cycle performance of the high-nickel ternary cathode material can be improved. On the other hand, the lithium cobalt borate belongs to a polyanion structure and has higher thermal stabilityQualitative and safety performance, thereby inhibiting the dissolution of transition metal atoms at high temperature, reducing the swelling of the cathode material during high-temperature storage, and improving the stability of the SEI film of the cathode material during high-temperature cycles.
Preferably, the particle size D50 of the high-nickel ternary material is 1-20 μm, such as 1 μm, 3 μm, 5 μm, 7 μm, 9 μm, 11 μm, 13 μm, 15 μm, 17 μm, 18 μm or 20 μm, but is not limited to the recited values, and other values not recited in this range are equally applicable, preferably 3-15 μm. In the present invention, if the particle size D50 of the high nickel ternary material is less than 3 μm, the tap density decreases, and there is a possibility that the side reaction of the positive electrode material with the electrolyte solution progresses and the cycle and safety are deteriorated. If the particle size D50 of the high nickel ternary material is larger than 15 μm, the specific surface area of the positive electrode material decreases, the interface with the electrolyte decreases, and the positive electrode resistance increases and the capacity decreases.
Preferably, the chemical formula of the high-nickel ternary material core is Li z Ni 1-x-y Co x M y O 2 Wherein 0.95. ltoreq. z.ltoreq.1.10, e.g. z is 0.95, 0.98, 1.00, 1.05 or 1.10 etc., 0. ltoreq. x.ltoreq.0.20, e.g. x is 0, 0.05, 0.10, 0.15 or 0.20 etc., 0. ltoreq. y.ltoreq.0.20, e.g. y is 0, 0.05, 0.10, 0.15 or 0.20 etc., M is any one or a combination of at least two of Mn, Al, Mg, Ti or Nb, typically but not limited to: combinations of Mn and Al, combinations of Al and Mg, combinations of Ti and Nb, and the like. In the invention, if z is less than or equal to 0.95, the lithium content of the anode material is insufficient, so that the cycle behavior is reduced, and if z is more than or equal to 1.10, redundant residual lithium and Ni are generated on the surface of the material 3+ Reduction to Ni 2+ An increase in the production of lithium nickel mixed rows, which ultimately leads to an increase in the impedance leading to a decrease in capacity and cycle, is therefore preferably 0.95. ltoreq. z.ltoreq.1.10.
In a second aspect, the present invention provides a method for preparing the ternary cathode material according to the first aspect, the method comprising the steps of:
(1) mixing a boron source and a cobalt source, and sintering in a protective atmosphere to obtain cobalt borate;
(2) and (2) mixing the cobalt borate and the high-nickel ternary material in the step (1), and heating in an oxidizing atmosphere to obtain the ternary cathode material.
In the preparation method provided by the invention, firstly, a boron source and a cobalt source react to form cobalt borate, and then the cobalt borate reacts with lithium hydroxide and lithium carbonate on the surface of the high-nickel ternary cathode material at high temperature to form lithium cobalt borate (LiCoBO) 3 )。
As a preferred embodiment of the present invention, the boron source in step (1) includes any one or a combination of at least two of orthoboric acid, metaboric acid, tetraboric acid, boron oxide, or ammonium borate, and typical but non-limiting combinations are: combinations of orthoboric acid and metaboric acid, metaboric acid and tetraboric acid, boron oxide and ammonium borate, and the like.
Preferably, the cobalt source in step (1) comprises any one of cobalt nitrate, cobalt hydroxide, cobalt carbonate, cobalt acetate or cobalt oxalate, or a combination of at least two of the following, typically but not limited to: a combination of cobalt nitrate and cobalt hydroxide, a combination of cobalt hydroxide and cobalt carbonate, a combination of cobalt carbonate, cobalt acetate, and cobalt oxalate, and the like.
Preferably, the mixing device used in step (1) is a mixer, preferably a high-speed mixer.
Preferably, the volume of each batch of mixed material is 1/2-3/4 of the mixer volume, e.g., 1/2, 2/3 or 3/4, although not limited to the recited values, and other unrecited values within the range are equally applicable. Here, if the mixed substance is filled too little, the productivity cannot be improved; if the mixture is too filled, there is a possibility that the mixing is insufficient.
Preferably, the mixer is operated at a speed of 50-100rpm, such as 50rpm, 60rpm, 70rpm, 80rpm, 90rpm or 100rpm, but not limited to the recited values, and other values not recited within the range of values are equally applicable.
Preferably, the mixing time in step (1) is 0.5 to 2 hours, such as 0.5 hour, 1 hour, 1.5 hour, 2 hours, etc., but not limited to the recited values, and other values not recited in the range of values are also applicable. Here, if the mixing speed time is too short, mixing unevenness is caused; if the mixing time is too long, the productivity is reduced.
In a preferred embodiment of the present invention, the sintering in step (1) is solid-phase sintering.
Preferably, the sintering temperature for the sintering in step (1) is 400-.
Preferably, the sintering time in step (1) is 3-5h, such as 3h, 3.5h, 4h, 4.5h or 5h, but not limited to the recited values, and other values not recited in the range of values are also applicable.
Preferably, the temperature rise rate of the sintering in step (1) is 3-5 deg.C/min, such as 3 deg.C/min, 3.5 deg.C/min, 4 deg.C/min, 4.5 deg.C/min, or 5 deg.C/min, but not limited to the values listed, and other values not listed in the range of the values are also applicable.
Preferably, the protective atmosphere in step (1) is any one of nitrogen atmosphere, argon atmosphere or carbon dioxide atmosphere or a combination of at least two of the above.
Preferably, the flow rate of the protective atmosphere gas introduced per 10kg of the mixture during the sintering in step (1) is 1-10L/h, such as 1L/h, 2L/h, 3L/h, 4L/h, 5L/h, 6L/h, 7L/h, 8L/h, 9L/h or 10L/h, but not limited to the recited values, and other values not recited in the range of the values are also applicable.
Preferably, the sintering of step (1) is carried out in a box furnace or kiln.
Preferably, the cobalt borate in step (1) is Co 2 B 2 O 5
In a preferred embodiment of the present invention, the particle size D50 of the high nickel ternary material is 1 to 20 μm, for example, 1 μm, 3 μm, 5 μm, 7 μm, 9 μm, 11 μm, 13 μm, 15 μm, 17 μm, 18 μm, or 20 μm, but is not limited to the above-mentioned values, and other values not shown in the above-mentioned range are also applicable, preferably 3 to 15 μm.
Preferably, the chemical formula of the high-nickel ternary material in the step (2) is Li z Ni 1-x-y Co x M y O 2 Wherein 0.95. ltoreq. z.ltoreq.1.10, e.g. z is 0.95, 0.98, 1.00, 1.05 or 1.10 etc., 0. ltoreq. x.ltoreq.0.20, e.g. x is 0, 0.05, 0.10, 0.15 or 0.20 etc., 0. ltoreq. y.ltoreq.0.20, e.g. y is 0, 0.05, 0.10, 0.15 or 0.20 etc., M is any one or a combination of at least two of Mn, Al, Mg, Ti or Nb, typically but not limited to: combinations of Mn and Al, combinations of Al and Mg, combinations of Ti and Nb, and the like. In the invention, if z is less than or equal to 0.95, the lithium content of the anode material is insufficient, so that the cycle behavior is reduced, and if z is more than or equal to 1.10, redundant residual lithium and Ni are generated on the surface of the material 3+ Reduction to Ni 2+ An increase in the production of lithium nickel mixed rows, which ultimately leads to an increase in impedance leading to a decrease in capacity and cycle, is therefore preferably 0.95. ltoreq. z.ltoreq.1.10.
Preferably, the mixing device used in the step (2) is a mixer, preferably a high-speed mixer.
Preferably, the volume of each batch of mixed material is 1/2-3/4, e.g., 1/2, 2/3, or 3/4, etc., of the volume of the mixer, but is not limited to the recited values, and other values not recited within this range of values are equally applicable. Here, if the mixed substance is filled too little, the productivity cannot be improved; if the mixture is filled too much, the mixing may be insufficient, and the crystallinity of the positive electrode material may be affected.
Preferably, the mixer is operated at a speed of 50-100rpm, such as 50rpm, 60rpm, 70rpm, 80rpm, 90rpm, or 100rpm, but not limited to the recited values, and other values not recited within the range are equally applicable. In the present invention, if the mixing speed is too low, mixing unevenness is caused; if the speed is too high, secondary particles on the surface of the positive electrode material are abraded, and the transfer rate of lithium ions and the cycle performance of the battery are affected.
Preferably, the mixing time in step (2) is 0.5-2h, such as 0.5h, 1h, 1.5h or 2h, but not limited to the recited values, and other values not recited in the range of values are also applicable. Here, if the mixing speed time is too short, mixing unevenness is caused; if the mixing time is too long, the productivity is reduced.
Preferably, in step (2), the mass ratio of the cobalt borate to the high nickel ternary material is (0.001-0.01):1, for example, 0.001:1, 0.003:1, 0.005:1, 0.007:1, 0.009:1 or 0.01:1, but not limited to the recited values, and other values not recited in this numerical range are equally applicable, preferably (0.001-0.005): 1. In the invention, if the mass ratio of the cobalt borate package to the high-nickel ternary material is less than 0.001:1, the coating effect is ineffective, and if the mass ratio of the cobalt borate package to the high-nickel ternary material is more than 0.005:1, the coating layer is too thick and uneven, the lithium ion migration is blocked, and the multiplying power and the cycle behavior are reduced.
And (3) heating from room temperature in the process of coating the high-nickel ternary material composite material with the cobalt borate in the step (2).
In the preferred embodiment of the present invention, in the step (2), the heating temperature is 200-500 ℃, for example, 200 ℃, 300 ℃, 400 ℃ or 500 ℃, but the heating temperature is not limited to the recited values, and other values not recited in the range of the values are also applicable.
Preferably, in step (2), the heating time is 5-10h, such as 5h, 6h, 7h, 8h, 9h or 10h, but not limited to the recited values, and other values not recited in the range of values are also applicable.
Preferably, in step (2), the heating rate is 3-5 deg.C/min, such as 3 deg.C/min, 3.5 deg.C/min, 4 deg.C/min, 4.5 deg.C/min, or 5 deg.C/min, but not limited to the values listed, and other values not listed in the range of values are also applicable.
Preferably, in the step (2), the oxidizing atmosphere is an oxygen atmosphere and/or an air atmosphere.
Preferably, the flow rate of the oxidizing atmosphere gas introduced per 10kg of the mixture during the heating in step (2) is 1 to 10L/h, such as 1L/h, 2L/h, 3L/h, 4L/h, 5L/h, 6L/h, 7L/h, 8L/h, 9L/h, or 10L/h, but not limited to the recited values, and other values not recited in the range of the recited values are also applicable.
Preferably, the heating of step (2) is performed in a box furnace or kiln.
As a further preferable technical scheme of the preparation method, the method comprises the following steps:
(1) mixing a boron source and a cobalt source in a mixer at a rotating speed of 50-100rpm for 0.5-2h, heating to 400-600 ℃ at a heating rate of 3-5 ℃/min in a protective atmosphere, and sintering for 3-5h to obtain cobalt borate;
the protective atmosphere comprises any one or the combination of at least two of nitrogen atmosphere, argon atmosphere and carbon dioxide atmosphere, and the gas flow of the protective atmosphere introduced into every 10kg of mixed materials in the sintering process is 1-10L/h;
(2) mixing the cobalt borate and the high-nickel ternary material in the step (1) in a mixer at the rotating speed of 50-100rpm for 0.5-2h, and heating to 200-500 ℃ at the heating rate of 3-5 ℃/min in an oxidizing atmosphere for 5-10h to obtain the ternary cathode material;
wherein the mass ratio of the cobalt borate to the high-nickel ternary material is (0.001-0.005) to 1; the particle size D50 of the high-nickel ternary material is 3-15 mu m, the oxidizing atmosphere is an oxygen atmosphere and/or an air atmosphere, and the flow rate of oxidizing atmosphere gas introduced into each 10kg of mixed material in the heating process is 1-10L/h.
In a third aspect, the present invention provides a lithium ion battery comprising the ternary cathode material according to the first aspect. The ternary cathode material provided by the invention is used on a lithium ion battery, obviously improves the rate discharge capacity and the cycle performance of the battery, and has good industrial application prospect.
Compared with the prior art, the invention has the following beneficial effects:
(1) the ternary cathode material provided by the invention has the advantages that the high-nickel ternary material core, the cobalt borate coating layer and the lithium cobalt borate positioned between the high-nickel ternary material core and the cobalt borate coating layer are matched with each other, so that the ternary cathode material provided by the invention is low in residual alkali content and good in rate discharge capacity and cycle performance. The residual alkali content can be controlled below 3500ppm, the minimum content is 2537ppm, the 0.1C capacity can reach 215mAh/g, the 4C capacity can reach 190mAh/g, and the capacity retention rate after 100 charge-discharge cycles can reach more than 90%.
(2) The preparation method provided by the invention has the advantages of short flow, simple operation and easy industrialized mass production, and can ensure that the cobalt borate reacts with the lithium hydroxide and the lithium carbonate on the surface of the high-nickel ternary material at high temperature to form the lithium cobalt borate, thereby further reducing the residual alkali content of the product and improving the electrochemical performance of the product.
Drawings
Fig. 1a is a Scanning Electron Microscope (SEM) picture of the cobalt borate coated ternary cathode material prepared in example 1 of the present invention;
FIG. 1b is a Scanning Electron Microscope (SEM) picture of the cobalt borate coated ternary cathode material prepared in example 7 of the present invention;
FIG. 1c is a Scanning Electron Microscope (SEM) picture of the cobalt borate coated ternary cathode material prepared in example 8 of the present invention;
fig. 2 is a first charge and discharge curve of the ternary cathode material coated with cobalt borate prepared in example 1 of the present invention and the ternary cathode material uncoated with cobalt borate prepared in comparative example 1;
fig. 3 is a graph showing cycle performance of the ternary cathode material coated with cobalt borate prepared in example 1 according to the present invention and the ternary cathode material uncoated with cobalt borate prepared in comparative example 1.
Detailed Description
In order to better illustrate the present invention and facilitate the understanding of the technical solutions of the present invention, the present invention is further described in detail below. However, the following examples are only simple examples of the present invention and do not represent or limit the scope of the present invention, which is defined by the claims.
The following are typical, but non-limiting, examples of the present invention:
example 1
This example prepares a ternary cathode material as follows:
(1) mixing orthoboric acid and cobalt nitrate according to a molar ratio of B to Co of 1:1 is put into a high-speed mixer (called high-speed mixer for short) with the volume occupying 1/5 of the high-speed mixer (namely the loading amount is 1/5), mixed for 0.5h at the speed of 100rpm, loaded into a sagger, put into a kiln, heated to 400 ℃ at the speed of 5 ℃/minKeeping the temperature for 5h, and introducing 1L/h nitrogen into the kiln. After sintering, crushing, sieving by a 325-mesh sieving machine to obtain Co 2 B 2 O 5
(2) Mixing Co 2 B 2 O 5 With a high nickel ternary material Li with an average particle size of 3 mu m 1.01 Ni 0.8 Co 0.1 Mn 0.1 O 2 Mixing the materials for 1h at a rotating speed of 50rpm on a high-speed mixer according to a mass ratio of 0.001:1 and a loading amount of 1/5, then filling the materials into a sagger, putting the sagger into a kiln, heating the sagger to 500 ℃ at a speed of 4 ℃/min, keeping the temperature for 5h, introducing oxygen into the kiln, and ensuring that the gas flow required by 10kg of mixed materials is 1L/h. After sintering, crushing, sieving by a 325-mesh sieving machine to obtain Co 2 B 2 O 5 Coated Li 1.01 Ni 0.8 Co 0.1 M 0.1 O 2 The composite ternary positive electrode material of (2).
Fig. 1a is a Scanning Electron Microscope (SEM) image of the ternary cathode material coated with cobalt borate prepared in this embodiment, and it can be seen from the image that the surface coating layer of the ternary cathode material coated with cobalt borate prepared in this embodiment is thin and uniform.
The test results of the ternary cathode material prepared in this example are shown in table 1.
The ternary cathode material prepared in this embodiment mainly comprises a high-nickel ternary material core and a cobalt borate coating layer, and the ternary cathode material further comprises lithium cobalt borate located between the high-nickel ternary material core and the cobalt borate coating layer. The particle size D50 of the high-nickel ternary material is 3 mu m, the thickness of the cobalt borate coating layer is 5nm, and the mass ratio of the cobalt borate coating layer to the high-nickel ternary material core is 0.001: 1.
Example 2
In this example, a ternary cathode material was prepared as follows:
(1) mixing boron oxide and cobalt hydroxide according to a molar ratio of B to Co of 1:1 and 3/4 are mixed in a high-speed mixer at the speed of 50rpm for 2 hours, then the mixture is filled in a sagger, and then the sagger is put in a kiln, the temperature is raised to 600 ℃ at the speed of 5 ℃/min, the temperature is kept for 3 hours, and 5L/h argon is introduced into the kiln. After sintering, crushing and sieving with 325 mesh sieveScreening by an extension to obtain Co 2 B 2 O 5
(2) Mixing Co 2 B 2 O 5 With a high nickel ternary material Li with an average particle size of 15 mu m 0.95 Ni 0.6 Co 0.2 Mn 0.2 O 2 Mixing the materials for 1h at a rotating speed of 100rpm on a high-speed mixer according to a mass ratio of 0.005:1 and a loading amount of 3/4, then filling the materials into a sagger, putting the sagger into a kiln, raising the temperature to 500 ℃ at a speed of 5 ℃/min, preserving the temperature for 10h, introducing air into the kiln, and ensuring that the gas flow required by 10kg of mixed materials is 10L/h. After sintering, crushing, sieving by a 325-mesh sieving machine to obtain Co 2 B 2 O 5 Coated Li 0.95 Ni 0.6 Co 0.2 M 0.2 O 2 The composite ternary positive electrode material of (1).
The test results of the ternary cathode material prepared in this example are shown in table 1.
The ternary cathode material prepared in this embodiment mainly comprises a high-nickel ternary material core and a cobalt borate coating layer, and the ternary cathode material further comprises lithium cobalt borate located between the high-nickel ternary material core and the cobalt borate coating layer. The particle size D50 of the high-nickel ternary material is 15 mu m, the thickness of the cobalt borate coating layer is 20nm, and the mass ratio of the cobalt borate coating layer to the high-nickel ternary material core is 0.005: 1.
Example 3
This example prepares a ternary cathode material as follows:
(1) mixing a mixture of tetraboric acid and cobalt carbonate in a molar ratio of B to Co of 1:1 and 3/5 in a high-speed mixer at a speed of 60rpm for 1h, filling in a sagger, putting in a kiln, heating to 500 ℃ at a speed of 3 ℃/min, keeping the temperature for 4h, and introducing 10L/h carbon dioxide into the kiln. After sintering, crushing, sieving by a 325-mesh sieving machine to obtain Co 2 B 2 O 5
(2) Mixing Co 2 B 2 O 5 With a high nickel ternary material Li with an average particle size of 10 mu m 1.0 Ni 0.65 Co 0.15 Mn 0.20 O 2 At high speed at a mass ratio of 0.003:1 and a loading of 3/4Mixing the materials on a mixer at a rotating speed of 70rpm for 1.5h, filling the materials in a sagger, putting the sagger in a kiln, heating the sagger to 300 ℃ at a speed of 3 ℃/min, keeping the temperature for 8h, introducing air into the kiln, and controlling the gas flow required by 10kg of mixed materials to be 8L/h. After sintering, crushing, sieving by a 325-mesh sieving machine to obtain Co 2 B 2 O 5 Coated Li 0.95 Ni 0.6 Co 0.2 Mn 0.2 O 2 The composite ternary positive electrode material of (1).
The test results of the ternary cathode material prepared in this example are shown in table 1.
The ternary cathode material prepared in this embodiment mainly comprises a high-nickel ternary material core and a cobalt borate coating layer, and the ternary cathode material further comprises lithium cobalt borate located between the high-nickel ternary material core and the cobalt borate coating layer. The particle size D50 of the high-nickel ternary material is 10 mu m, the thickness of the cobalt borate coating layer is 15nm, and the mass ratio of the cobalt borate coating layer to the high-nickel ternary material core is 0.003: 1.
Example 4
This example prepares a ternary cathode material as follows:
(1) mixing tetraboric acid and cobalt acetate in a molar ratio of B to Co of 1:1 and 1/2 in a high-speed mixer at a speed of 100rpm for 0.5h, filling in a sagger, placing in a kiln, heating to 450 ℃ at a speed of 4 ℃/min, keeping the temperature for 3h, and introducing 4L/h nitrogen into the kiln. After sintering, crushing, sieving by a 325-mesh sieving machine to obtain Co 2 B 2 O 5
(2) Mixing Co 2 B 2 O 5 With a high nickel ternary material Li with an average particle size of 8 mu m 1.05 Ni 0.86 Co 0.10 Mn 0.4 O 2 Mixing the materials for 0.5h at a mass ratio of 0.002:1 and a loading amount of 3/4 on a high-speed mixer at a rotating speed of 100rpm, filling the materials into a sagger, placing the sagger in a kiln, heating the sagger to 300 ℃ at a speed of 4 ℃/min, preserving the heat for 10h, and introducing air into the kiln, wherein the gas flow required by each 10kg of mixed materials is 5L/h. After sintering, crushing, sieving by a 325-mesh sieving machine to obtain Co 2 B 2 O 5 Coated Li 1.05 Ni 0.86 Co 0.10 Mn 0.4 O 2 The composite ternary positive electrode material of (1).
The test results of the ternary cathode material prepared in this example are shown in table 1.
The ternary cathode material prepared in this embodiment mainly comprises a high-nickel ternary material core and a cobalt borate coating layer, and the ternary cathode material further comprises lithium cobalt borate located between the high-nickel ternary material core and the cobalt borate coating layer. The particle size D50 of the high-nickel ternary material is 8 mu m, the thickness of the cobalt borate coating layer is 10nm, and the mass ratio of the cobalt borate coating layer to the high-nickel ternary material core is 0.002: 1.
Example 5
This example prepares a ternary cathode material as follows:
(1) mixing a mixture of tetraboric acid and cobalt oxalate at a molar ratio of B to Co of 1:1 and 1/2 are mixed in a high-speed mixer at the speed of 100rpm for 0.5h, then the mixture is filled in a sagger, and then the sagger is put in a kiln, the temperature is raised to 450 ℃ at the speed of 4 ℃/min, the temperature is kept for 3h, and 1L/h of nitrogen is introduced into the kiln. After sintering, crushing, sieving by a 325-mesh sieving machine to obtain Co 2 B 2 O 5
(2) Mixing Co 2 B 2 O 5 With a high nickel ternary material Li with an average particle size of 5 mu m 1.02 Ni 0.80 Co 0.10 Mn 0.10 O 2 Mixing the materials for 0.5h at a rotating speed of 100rpm on a high-speed mixer according to a mass ratio of 0.002:1 and a loading amount of 3/4, then filling the materials into a sagger, putting the sagger into a kiln, heating the sagger to 300 ℃ at a speed of 4 ℃/min, preserving the heat for 10h, and introducing air into the kiln, wherein the gas flow required by 10kg of mixed materials is 1L/h. After sintering, crushing, sieving by a 325-mesh sieving machine to obtain Co 2 B 2 O 5 Coated Li 1.02 Ni 0.80 Co 10 Mn 10 O 2 The composite ternary positive electrode material of (1).
The test results of the ternary cathode material prepared in this example are shown in table 1.
The ternary cathode material prepared by the embodiment mainly comprises a high-nickel ternary material core and a cobalt borate coating layer, and the ternary cathode material further comprises lithium cobalt borate positioned between the high-nickel ternary material core and the cobalt borate coating layer. The particle size D50 of the high-nickel ternary material is 5 mu m, the thickness of the cobalt borate coating layer is 10nm, and the mass ratio of the cobalt borate coating layer to the high-nickel ternary material core is 0.002: 1.
Example 6
This example prepares a ternary cathode material as follows:
(1) mixing tetraboric acid and boric acid with a mixture of cobalt acetate and cobalt nitrate in a molar ratio of B: Co of 1:1 and 1/2 in a high-speed mixer at a speed of 100rpm for 1h, filling in a sagger, placing in a kiln, heating to 440 ℃ at 4 ℃/min, keeping the temperature for 5h, and introducing 10L/h nitrogen into the kiln. After sintering, crushing, sieving by a 325-mesh sieving machine to obtain Co 2 B 2 O 5
(2) Mixing Co 2 B 2 O 5 With a high nickel ternary material Li with an average particle size of 12 mu m 1.03 Ni 0.80 Co 0.12 Mn 0.8 O 2 Mixing the materials for 1h at a rotating speed of 100rpm on a high-speed mixer according to a mass ratio of 0.005:1 and a loading amount of 3/5, then filling the materials into a sagger, putting the sagger into a kiln, heating the sagger to 500 ℃ at a speed of 4 ℃/min, keeping the temperature for 8h, introducing air into the kiln, and ensuring that the gas flow required by 10kg of mixed materials is 3L/h. After sintering, crushing, sieving by a 325-mesh sieving machine to obtain Co 2 B 2 O 5 Coated Li 1.03 Ni 0.80 Co 0.12 Mn 0.8 O 2 The composite ternary positive electrode material of (1).
The test results of the ternary cathode material prepared in this example are shown in table 1.
The ternary cathode material prepared in this embodiment mainly comprises a high-nickel ternary material core and a cobalt borate coating layer, and the ternary cathode material further comprises lithium cobalt borate located between the high-nickel ternary material core and the cobalt borate coating layer. The particle size D50 of the high-nickel ternary material is 12 mu m, wherein the thickness of the cobalt borate coating layer is 20nm, and the mass ratio of the cobalt borate coating layer to the high-nickel ternary material core is 0.005: 1.
Example 7
The specific preparation process of this example is as in example 1, except that, in step (2), Co 2 B 2 O 5 With high-nickel ternary material Li 1.01 Ni 0.8 Co 0.1 M 0.1 O 2 Coating is carried out according to the mass ratio of 0.01: 1.
Fig. 1b is a Scanning Electron Microscope (SEM) image of the ternary cathode material coated with cobalt borate prepared in this example, and it can be seen from the image that the ternary cathode material prepared in this example has a coating substance on it obviously because the coating quality is too high.
The test results of the ternary cathode material prepared in this example are shown in table 1.
The ternary cathode material prepared by the embodiment mainly comprises a high-nickel ternary material core and a cobalt borate coating layer, and the ternary cathode material further comprises lithium cobalt borate positioned between the high-nickel ternary material core and the cobalt borate coating layer. The particle size D50 of the high-nickel ternary material is 3 mu m, wherein the thickness of the cobalt borate coating layer is 50nm, and the mass ratio of the cobalt borate coating layer to the high-nickel ternary material core is 0.01: 1.
Example 8
The specific preparation process of this example is as in example 1, except that in step (2), Co is added 2 B 2 O 5 With high-nickel ternary material Li 1.01 Ni 0.8 Co 0.1 Mn 0.1 O 2 Mixing was carried out at 110rpm for 0.5 h.
Fig. 1c is a Scanning Electron Microscope (SEM) image of the ternary cathode material coated with cobalt borate prepared in this example, and it can be seen from the image that the particle surface of the ternary cathode material prepared in this example is damaged due to the high rotation speed of the high-speed mixer.
The test results of the ternary cathode material prepared in this example are shown in table 1.
The ternary cathode material prepared in this embodiment mainly comprises a high-nickel ternary material core and a cobalt borate coating layer, and the ternary cathode material further comprises lithium cobalt borate located between the high-nickel ternary material core and the cobalt borate coating layer. The particle size D50 of the high-nickel ternary material is 3 mu m, the thickness of the cobalt borate coating layer is 5nm, and the mass ratio of the cobalt borate coating layer to the high-nickel ternary material core is 0.001: 1.
Example 9
The specific preparation process of this example is as in example 1, except that in step (2), the mixing time on the high speed mixer is 2h, and the temperature is raised to 200 ℃ in the kiln and maintained.
The test results of the ternary cathode material prepared in this example are shown in table 1.
The ternary cathode material prepared in this embodiment mainly comprises a high-nickel ternary material core and a cobalt borate coating layer, and the ternary cathode material further comprises lithium cobalt borate located between the high-nickel ternary material core and the cobalt borate coating layer. The particle size D50 of the high-nickel ternary material is 3 mu m, the thickness of the cobalt borate coating layer is 5nm, and the mass ratio of the cobalt borate coating layer to the high-nickel ternary material core is 0.001: 1.
Example 10
The specific production method of this example refers to example 1 except that in step (2), a high nickel ternary material Li having an average particle diameter of 1 μm is used 1.01 Ni 0.8 Co 0.1 Mn 0.1 O 2
The test results of the ternary cathode material prepared in this example are shown in table 1.
The ternary cathode material prepared in this embodiment mainly comprises a high-nickel ternary material core and a cobalt borate coating layer, and the ternary cathode material further comprises lithium cobalt borate located between the high-nickel ternary material core and the cobalt borate coating layer. The particle size D50 of the high-nickel ternary material is 1 mu m, the thickness of the cobalt borate coating layer is 5nm, and the mass ratio of the cobalt borate coating layer to the high-nickel ternary material core is 0.001: 1.
Example 11
The specific production method of this example refers to example 1 except that in step (2), a high nickel ternary material Li having an average particle diameter of 20 μm is used 1.01 Ni 0.8 Co 0.1 Mn 0.1 O 2
The test results of the ternary cathode material prepared in this example are shown in table 1.
The ternary cathode material prepared by the embodiment mainly comprises a high-nickel ternary material core and a cobalt borate coating layer, and the ternary cathode material further comprises lithium cobalt borate positioned between the high-nickel ternary material core and the cobalt borate coating layer. The particle size D50 of the high-nickel ternary material is 20 mu m, the thickness of the cobalt borate coating layer is 5nm, and the mass ratio of the cobalt borate coating layer to the high-nickel ternary material core is 0.001: 1.
Comparative example 1
This comparative example uses the same high nickel ternary material (Li) as in example 1 1.01 Ni 0.8 Co 0.1 Mn 0.1 O 2 ) It was not coated at all for comparison.
Fig. 2 is a first charge and discharge curve of the ternary cathode material coated with cobalt borate prepared in example 1 of the present invention and the ternary cathode material uncoated with cobalt borate prepared in comparative example 1, and it can be seen from the figure that the first discharge capacity of the ternary cathode material coated with cobalt borate prepared in example 1 is 204mAh/g, which is higher than the discharge capacity of the ternary cathode material uncoated with cobalt borate in comparative example 1 by 200mAh/g, indicating that the coated cobalt borate reacts with lithium hydroxide and lithium carbonate of the high nickel ternary material to form lithium cobalt borate having electrochemical capacity, thus resulting in an increase in charge and discharge capacity of the coated ternary cathode material.
Fig. 3 is a cycle performance curve of the ternary cathode material coated with cobalt borate prepared in example 1 of the present invention and the ternary cathode material not coated with cobalt borate prepared in comparative example 1, and it can be seen from the curves that the cycle retention rate of 100 cycles of the ternary cathode material coated with cobalt borate prepared in example 1 is 93.2%, which is higher than the cycle retention rate of 82.5% of the ternary cathode material not coated with cobalt borate in comparative example 1, which indicates that the coated cobalt borate improves the surface stability of the ternary cathode material on the one hand, and the lithium cobalt borate has electronic and ionic conductivities on the other hand, so that the cycle retention rate of the ternary material is improved.
The test results of the high nickel ternary positive electrode material in this comparative example are shown in table 1.
Test method
The ternary positive electrode material products obtained in the above examples and comparative examples were subjected to performance testing by the following method.
The particle size of the anode material is tested by adopting a Malvern laser particle size tester MS 2000.
The surface morphology, particle size, etc. of the sample were observed using a Hitachi S4800 scanning electron microscope.
Electrochemical cycling performance was tested using the following method: mixing a positive electrode material made of a cobalt borate coated high-nickel ternary composite material with conductive carbon black and a binder PVDF (polyvinylidene fluoride) according to a mass ratio of 80:10:10, adding NMP (N-methyl pyrrolidone) to prepare uniform slurry, coating the uniform slurry on a copper foil, drying the uniform slurry in an oven, rolling the uniform slurry under the pressure of 10Mpa, and cutting the uniform slurry into a circular pole piece with the diameter of 14 mm. Assembling a lithium ion battery according to a CR2025 type button battery in industry, wherein a diaphragm is a Cellgard diaphragm, and an electrolyte is 1mol/L LiPF (lithium ion power) with a solvent of EC/PC/DEC 6 The solution, the counter electrode is a lithium sheet. The whole assembly process is assembled in a glove box filled with argon, and the oxygen content and the moisture content in the glove box are controlled to be below 0.5 ppm. The lithium ion battery test conditions are as follows: the temperature is 25 +/-1 ℃, the voltage range of the charge-discharge cycle is 3.0-4.2V, the current is 0.1C (20mAh/g), and the cycle test is carried out for 100 weeks by charging 1℃ according to 0.5C.
The sample was tested for the amount of residual base using an automatic potentiometric titrator (model: METTLER TOLEDO G20).
The test results of the above test are shown in table 1.
TABLE 1
Figure BDA0001872698010000181
Figure BDA0001872698010000191
It can be seen from the above examples and comparative examples that the ternary positive electrode materials prepared in examples 1 to 6 and example 9 had a suitable thickness of the cobalt borate coating layer and a suitable D50 for the high nickel ternary material, and reacted to form lithium cobalt borate, so that the rate discharge capacity and cycle performance were both excellent and the residual alkali content was low. The cobalt borate coating layer of example 7 was too thick to cause a decrease in capacity and cycle, and the high-speed mixer rotation speed in example 8 caused a particle surface destruction of the ternary positive electrode material, resulting in a decrease in discharge capacity and cycle behavior. The D50 for the high nickel ternary materials of examples 10 and 11 is not in the most preferred range, resulting in a reduction in performance compared to example 1. Comparative example 1 the capacity and 100 cycle are significantly inferior to example 1 because of the absence of the cobalt borate coating, indicating that coating cobalt borate under the conditions of the present application can improve capacity and cycle performance compared to no coating.
The applicant states that the present invention is illustrated by the above examples to show the detailed process equipment and process flow of the present invention, but the present invention is not limited to the above detailed process equipment and process flow, i.e. it does not mean that the present invention must rely on the above detailed process equipment and process flow to be implemented. It should be understood by those skilled in the art that any modifications of the present invention, equivalent substitutions of the raw materials of the product of the present invention, and the addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.

Claims (41)

1. The ternary cathode material is characterized by mainly comprising a high-nickel ternary material core and a cobalt borate coating layer;
the cobalt borate coating layer is Co 2 B 2 O 5 A coating layer;
the ternary cathode material also comprises lithium cobalt borate positioned between the high-nickel ternary material core and the cobalt borate coating layer.
2. The ternary positive electrode material according to claim 1,
the thickness of the cobalt borate coating layer is 2-50 nm.
3. The ternary positive electrode material according to claim 2, wherein the cobalt borate coating layer has a thickness of 5 to 20 nm.
4. The ternary cathode material according to claim 1, wherein the mass ratio of the cobalt borate coating layer to the high nickel ternary material core is (0.001-0.01): 1.
5. The ternary cathode material according to claim 4, wherein the mass ratio of the cobalt borate coating layer to the high nickel ternary material core is (0.001-0.005): 1.
6. The ternary positive electrode material according to claim 1 or 2, wherein the particle size D50 of the high-nickel ternary material is 1-20 μ ι η.
7. The ternary positive electrode material according to claim 6, wherein the particle size D50 of the high nickel ternary material is 3-15 μm.
8. The ternary positive electrode material according to claim 1 or 2, wherein the chemical formula of the high nickel ternary material core is Li z Ni 1-x-y Co x M y O 2 Wherein z is more than or equal to 0.95 and less than or equal to 1.10, x is more than or equal to 0 and less than or equal to 0.20, y is more than or equal to 0 and less than or equal to 0.20, and M is any one or the combination of at least two of Mn, Al, Mg, Ti or Nb.
9. A method for preparing a ternary positive electrode material according to any one of claims 1 to 8, characterized in that it comprises the following steps:
(1) mixing a boron source and a cobalt source, and sintering in a protective atmosphere to obtain cobalt borate, wherein the cobalt borate is Co 2 B 2 O 5
(2) And (2) mixing the cobalt borate and the high-nickel ternary material in the step (1), and heating in an oxidizing atmosphere to obtain the ternary cathode material.
10. The method according to claim 9, wherein the boron source of step (1) comprises any one of orthoboric acid, metaboric acid, tetraboric acid, boron oxide or ammonium borate or a combination of at least two thereof.
11. The method of claim 9, wherein the cobalt source of step (1) comprises any one of cobalt nitrate, cobalt hydroxide, cobalt carbonate, cobalt acetate, or cobalt oxalate, or a combination of at least two thereof.
12. The method according to claim 9, wherein the mixing in step (1) is carried out using a mixer.
13. The method according to claim 12, wherein the mixing in step (1) is carried out using a high-speed mixer.
14. The method of claim 12, wherein the volume of each batch of mixed material is 1/2-3/4 of the volume of the mixer.
15. The method of claim 12, wherein the mixer is rotated at 50-100 rpm.
16. The method of claim 9, wherein the mixing in step (1) is carried out for a period of time of 0.5 to 2 hours.
17. The method according to claim 9, wherein the sintering in step (1) is solid-phase sintering.
18. The method as claimed in claim 9, wherein the sintering temperature of the sintering in step (1) is 400-600 ℃.
19. The method according to claim 9, wherein the sintering time in step (1) is 3 to 5 hours.
20. The method according to claim 9, wherein the temperature increase rate in the sintering of step (1) is 3 to 5 ℃/min.
21. The method according to claim 9, wherein the protective atmosphere in step (1) is any one of a nitrogen atmosphere, an argon atmosphere, or a carbon dioxide atmosphere, or a combination of at least two of them.
22. The preparation method of claim 9, wherein the flow rate of the protective atmosphere gas introduced per 10kg of the mixed material during the sintering in the step (1) is 1-10L/h.
23. The method according to claim 9, wherein the sintering of step (1) is performed in a box furnace or a kiln furnace.
24. The method according to claim 9, wherein the particle size D50 of the high nickel ternary material is 1-20 μm.
25. The method of claim 24, wherein the high nickel ternary material has a particle size D50 of 3-15 μ ι η.
26. The method according to claim 9, wherein the high nickel ternary material of step (2) has a chemical formula of Li z Ni 1-x-y Co x M y O 2 Wherein z is more than or equal to 0.95 and less than or equal to 1.10, x is more than or equal to 0 and less than or equal to 0.20, y is more than or equal to 0 and less than or equal to 0.20, and M is any one or the combination of at least two of Mn, Al, Mg, Ti or Nb.
27. The method according to claim 9, wherein the mixing in step (2) is carried out using a mixer.
28. The method according to claim 27, wherein the mixing in step (2) is carried out using a high-speed mixer.
29. The method of claim 28, wherein the volume of each batch of mixed material is 1/2-3/4 of the volume of the mixer.
30. The method of claim 29, wherein the mixer rotates at 50-100 rpm.
31. The method of claim 9, wherein the mixing in step (2) is carried out for a period of time of 0.5 to 2 hours.
32. The preparation method according to claim 9, wherein in the step (2), the mass ratio of the cobalt borate to the high nickel ternary material is (0.001-0.01): 1.
33. The method according to claim 32, wherein in the step (2), the mass ratio of the cobalt borate to the high nickel ternary material is (0.001-0.005): 1.
34. The method as claimed in claim 9, wherein the heating temperature in step (2) is 200-500 ℃.
35. The method according to claim 9, wherein the heating time in the step (2) is 5 to 10 hours.
36. The production method according to claim 9, wherein in the step (2), the heating rate is 3 to 5 ℃/min.
37. The production method according to claim 9, wherein in the step (2), the oxidizing atmosphere is an oxygen atmosphere and/or an air atmosphere.
38. The method according to claim 9, wherein the flow rate of the oxidizing atmosphere gas is 1 to 10L/h per 10kg of the mixed material during the heating in the step (2).
39. The method of claim 9, wherein the heating of step (2) is performed in a box furnace or kiln.
40. The method for preparing according to claim 9, characterized in that it comprises the following steps:
(1) mixing a boron source and a cobalt source in a mixer at a rotating speed of 50-100rpm for 0.5-2h, heating to 400-600 ℃ at a heating rate of 3-5 ℃/min in a protective atmosphere, and sintering for 3-5h to obtain cobalt borate;
the protective atmosphere comprises any one or the combination of at least two of nitrogen atmosphere, argon atmosphere and carbon dioxide atmosphere, and the gas flow of the protective atmosphere introduced into every 10kg of mixed materials in the sintering process is 1-10L/h;
(2) mixing the cobalt borate and the high-nickel ternary material in the step (1) in a mixer at the rotating speed of 50-100rpm for 0.5-2h, and heating to 200-500 ℃ at the heating rate of 3-5 ℃/min in an oxidizing atmosphere for 5-10h to obtain the ternary cathode material;
wherein the mass ratio of the cobalt borate to the high-nickel ternary material is (0.001-0.005) to 1; the particle size D50 of the high-nickel ternary material is 3-15 mu m, the oxidizing atmosphere is an oxygen atmosphere and/or an air atmosphere, and the flow rate of oxidizing atmosphere gas introduced into each 10kg of mixed material in the heating process is 1-10L/h.
41. A lithium ion battery comprising the ternary cathode material of any of claims 1-8.
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