Coated modified nickel cobalt lithium manganate positive electrode material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of lithium ion batteries, in particular to a coated modified nickel cobalt lithium manganate positive electrode material as well as a preparation method and application thereof. The preparation method of the coated modified nickel cobalt lithium manganate positive electrode material comprises the following steps: obtaining a nickel cobalt lithium manganate matrix material; conducting polymer monomers are subjected to in-situ polymerization on the surfaces of the aluminum oxide powder and the titanium oxide powder to obtain a coating material; and coating the surface of the nickel cobalt lithium manganate matrix material with the coating material, and drying to prepare the coated modified nickel cobalt lithium manganate positive electrode material. The surface of the nickel cobalt lithium manganate base material is coated with the coating material prepared by in-situ polymerization of the aluminum oxide, the titanium oxide and the conductive polymer monomer, so that the conductivity and the structural stability of the coated nickel cobalt lithium manganate positive electrode material are improved; and the interface side reaction between the positive electrode material and the electrolyte can be effectively reduced, so that the specific capacity, the rate capability and the cycle life of the nickel cobalt lithium manganate material are effectively and comprehensively improved.

Description

Technical Field

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

[0002] With the widespread application of lithium-ion batteries in electronic devices and electric vehicles, the performance requirements for cathode materials are becoming increasingly stringent. Lithium nickel cobalt manganese oxide (LiNi) is a suitable cathode material. x Co y Mn z O2 (NCM) is one of the most promising ternary cathode materials, with relatively low preparation costs. However, it still suffers from problems such as low specific capacity, poor rate performance, and rapid capacity decay. Therefore, how to comprehensively improve the specific capacity, cycle performance, and rate performance of lithium nickel cobalt manganese oxide (LCM) materials has become a key technical challenge that urgently needs to be solved. Summary of the Invention

[0003] Therefore, the technical problem to be solved by the present invention is to overcome the shortcomings of existing lithium nickel cobalt manganese oxide materials in achieving comprehensive improvement in specific capacity, cycle performance and rate performance, thereby providing a coated modified lithium nickel cobalt manganese oxide cathode material, its preparation method and application to solve the above problems.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] In a first aspect, the present invention provides a method for preparing a coated modified lithium nickel cobalt manganese oxide cathode material, comprising:

[0006] Obtain lithium nickel cobalt manganese oxide matrix material;

[0007] The coating material was obtained by in-situ polymerization of conductive polymer monomers on the surfaces of alumina powder and titanium dioxide powder.

[0008] The coated modified lithium nickel cobalt manganese oxide cathode material is prepared by coating the surface of the lithium nickel cobalt manganese oxide matrix material with the coating material and then drying it.

[0009] Furthermore, the mass ratio of the alumina powder, titanium dioxide powder and conductive polymer monomer is (1-3):(1-2):(2-5).

[0010] Furthermore, the chemical formula of the lithium nickel cobalt manganese oxide matrix material is LiNi x Co y Mn z O2; where 0.5≤x≤0.8, 0.1≤y≤0.3, 0.1<z≤0.3, and x+y+z=1.

[0011] Furthermore, the ratio of the total mass of alumina powder and titanium oxide powder in the coating material to the mass of lithium nickel cobalt manganese oxide matrix material is 1:(4-5);

[0012] And / or, the conductive polymer monomer is a pyrrole monomer;

[0013] And / or, the coating method is ball milling, and the ball milling process parameters are preferably ball milling at a speed of 300-500 rpm for 2-4 hours;

[0014] And / or, the drying process is carried out at a temperature of 80-100°C for a duration of 12-24 hours.

[0015] Furthermore, the in-situ polymerization process involves adding alumina powder and titanium dioxide powder to an organic solvent for ultrasonic dispersion to form a uniform suspension, then adding conductive polymer monomers and an initiator to the suspension to initiate a polymerization reaction and obtain the coating material. In this invention, the ultrasonic dispersion time is 30-60 minutes, and stirring is performed simultaneously during the polymerization reaction.

[0016] Furthermore, the mass ratio of the conductive polymer monomer to the initiator is (1-3):1, preferably 2:1;

[0017] And / or, based on 100 mL of organic solvent, the total mass of the alumina powder and titanium dioxide powder is 2-3 g;

[0018] And / or, the polymerization reaction is carried out at room temperature for 3-5 hours; in this invention, the room temperature is 25±5℃.

[0019] And / or, the organic solvent is ethanol and / or acetone;

[0020] And / or, the initiator is ammonium persulfate.

[0021] Furthermore, the process for obtaining the lithium nickel cobalt manganese oxide matrix material is as follows:

[0022] According to the stoichiometric ratio of lithium nickel cobalt manganese oxide matrix material, nickel source, cobalt source, and manganese source are weighed and mixed with water to form a mixed solution;

[0023] A complexing agent was added to the mixed solution and the pH of the system was adjusted to 8-10 using a pH adjuster. At the same time, the system temperature was controlled at 60-80℃ for 2-4 hours to obtain the precursor.

[0024] The precursor is dried, then a lithium source is added and mixed, and then calcined in an oxygen-containing atmosphere at 600-800℃ for 4-10 hours to obtain lithium nickel cobalt manganese oxide matrix material.

[0025] Furthermore, the nickel source includes, but is not limited to, at least one of nickel sulfate and nickel nitrate;

[0026] And / or, the cobalt source includes, but is not limited to, at least one of cobalt sulfate and cobalt nitrate;

[0027] And / or, the manganese source includes, but is not limited to, at least one of manganese sulfate and manganese nitrate;

[0028] And / or, the lithium source includes, but is not limited to, at least one of lithium carbonate and lithium hydroxide;

[0029] And / or, the complexing agent includes, but is not limited to, at least one of ethylenediaminetetraacetic acid (EDTA) and citric acid;

[0030] And / or, the pH adjuster includes, but is not limited to, an aqueous solution of sodium hydroxide;

[0031] And / or, in the process of obtaining the lithium nickel cobalt manganese oxide matrix material, the ratio of the total mass of the nickel source, cobalt source, and manganese source to the mass of water and complexing agent is 1:(0.1-1.0):(0-0.5). In this invention, the use of a complexing agent is not absolutely necessary and can be added or not, but considering the comprehensive performance of the matrix material, it is generally chosen to add a complexing agent.

[0032] Secondly, the present invention also provides a coated modified lithium nickel cobalt manganese oxide cathode material, which is prepared by the above-described method for preparing coated modified lithium nickel cobalt manganese oxide cathode material.

[0033] Thirdly, the present invention also provides a lithium-ion battery comprising the above-mentioned coated modified lithium nickel cobalt manganese oxide cathode material.

[0034] The technical solution of this invention has the following advantages:

[0035] 1. A method for preparing a coated modified lithium nickel cobalt manganese oxide cathode material, comprising: obtaining a lithium nickel cobalt manganese oxide matrix material; using conductive polymer monomers to perform in-situ polymerization on the surfaces of alumina powder and titanium oxide powder to obtain a coating material; coating the coating material onto the surface of the lithium nickel cobalt manganese oxide matrix material and drying it to obtain the coated modified lithium nickel cobalt manganese oxide cathode material. This invention, by coating the surface of the lithium nickel cobalt manganese oxide matrix material with a coating material made from alumina, titanium oxide, and conductive polymer monomers through in-situ polymerization, improves the conductivity and structural stability of the coated lithium nickel cobalt manganese oxide cathode material, allowing for more full utilization of the electrode material's performance during charge and discharge, thereby improving the specific capacity and rate performance of the electrode material; and effectively reducing interfacial side reactions between the cathode material and the electrolyte, thereby improving the battery's cycle life.

[0036] 2. In the preparation method of the coated modified lithium nickel cobalt manganese oxide cathode material of the present invention, by controlling the mass ratio of alumina powder, titanium oxide powder and conductive polymer monomer in the range of (1-3):(1-2):(2-5), a good performance synergy effect can be achieved, and the electrochemical performance of lithium nickel cobalt manganese oxide cathode material can be further improved.

[0037] 3. In the preparation method of the coated modified lithium nickel cobalt manganese oxide cathode material of the present invention, if the coating layer is too thin, it may not be able to effectively suppress the side reactions of the electrolyte, resulting in poor stability of the cathode material. If the coating layer is too thick, it is easy to increase the interfacial impedance of the cathode material, hindering lithium-ion diffusion and reducing specific capacity and rate performance. However, the present invention limits the ratio of the total mass of alumina powder and titanium oxide powder in the coating material to the mass of lithium nickel cobalt manganese oxide matrix material to within the range of 1:(4-5), which can effectively balance the lithium diffusion effect and interfacial stability in the lithium nickel cobalt manganese oxide active material, thereby further improving the electrochemical performance of the lithium nickel cobalt manganese oxide cathode material.

[0038] 4. In the preparation method of the coated modified lithium nickel cobalt manganese oxide cathode material of the present invention, by adopting suitable co-precipitation conditions of matrix material and subsequent calcination process, the stability of matrix material can be effectively maintained, thereby optimizing the rate performance and other properties of lithium nickel cobalt manganese oxide cathode material. Attached Figure Description

[0039] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0040] Figure 1 These are cycle curve test diagrams of the cathode materials prepared in Examples 1, 2, and 3 of this invention, as well as Comparative Examples 6 and 7. Detailed Implementation

[0041] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0042] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0043] Example 1

[0044] This embodiment provides a method for preparing a coated modified lithium nickel cobalt manganese oxide cathode material, the specific steps of which are as follows:

[0045] 1) Obtaining lithium nickel cobalt manganese oxide matrix material: Following the lithium nickel cobalt manganese oxide matrix material LiNi 0.6 Co 0.2 Mn 0.2 Nickel sulfate (NiSO4·6H2O), cobalt sulfate (CoSO4·7H2O), and manganese sulfate (MnSO4·H2O) were weighed out in stoichiometric proportions and mixed with deionized water to form a mixed solution. Ethylenediaminetetraacetic acid (EDTA) was added to the mixed solution as a complexing agent, and the pH of the system was adjusted to 8 using sodium hydroxide aqueous solution. The system temperature was controlled at 60℃ for 2 hours to obtain a precursor. The precursor was dried at 80℃ for 12 hours, then lithium hydroxide (LiOH·H2O) was added and mixed thoroughly. The mixture was then calcined in oxygen at 600℃ for 4 hours to obtain a lithium nickel cobalt manganese oxide matrix material. The mass ratio of nickel sulfate, cobalt sulfate, and manganese sulfate to deionized water and EDTA was 1:0.2:0.2.

[0046] 2) Obtaining the coating material: 1g of alumina powder (particle size 0.3-2μm) and 1g of titanium dioxide powder (particle size 30nm) were added to 100mL of ethanol and ultrasonically dispersed for 30min to form a uniform suspension. 2g of pyrrole monomer and 1g of ammonium persulfate (initiator) were added to the suspension and stirred at room temperature for 3h to carry out the polymerization reaction to obtain the coating material.

[0047] 3) Coating treatment: Transfer all the coating material obtained in step 2) to a ball mill and add 10g of the lithium nickel cobalt manganese oxide matrix material obtained in step 1). Ball mill at 300 rpm for 2 hours to make the coating material uniformly coat the surface of the matrix material. Dry the ball-milled product at 80℃ for 12 hours to obtain the coated modified lithium nickel cobalt manganese oxide cathode material.

[0048] Example 2

[0049] This embodiment provides a method for preparing a coated modified lithium nickel cobalt manganese oxide cathode material, the specific steps of which are as follows:

[0050] 1) Obtaining lithium nickel cobalt manganese oxide matrix material: Following the lithium nickel cobalt manganese oxide matrix material LiNi 0.7 Co 0.15 Mn 0.15Nickel nitrate (Ni(NO3)2·6H2O), cobalt nitrate (Co(NO3)2·6H2O), and manganese nitrate (Mn(NO3)2·4H2O) were weighed out in stoichiometric proportions and mixed with deionized water to form a mixed solution. Citric acid was added to the mixed solution as a complexing agent, and the pH of the system was adjusted to 9 using sodium hydroxide aqueous solution. The system temperature was controlled at 70℃ for 3 hours to obtain a precursor. The precursor was dried at 90℃ for 18 hours, lithium hydroxide (LiOH·H2O) was added, and then the mixture was calcined in oxygen at 700℃ for 5 hours to obtain lithium nickel cobalt manganese oxide matrix material. The mass ratio of nickel nitrate, cobalt nitrate, and manganese nitrate to deionized water and citric acid was 1:0.4:0.1.

[0051] 2) Obtaining the coating material: 2g of alumina powder (0.3-2μm) and 1.5g of titanium dioxide powder (30nm) were added to 150mL of ethanol and ultrasonically dispersed for 45min to form a uniform suspension. 3g of pyrrole monomer and 1.5g of ammonium persulfate (initiator) were added to the suspension and stirred at room temperature for 4h to carry out the polymerization reaction to obtain the coating material.

[0052] 3) Coating treatment: Transfer all the coating material obtained in step 2) to a ball mill and add 15g of the lithium nickel cobalt manganese oxide matrix material obtained in step 1). Ball mill at 400 rpm for 3 hours to make the coating material uniformly coat the surface of the matrix material. Dry the ball-milled product at 90℃ for 18 hours to obtain the coated modified lithium nickel cobalt manganese oxide cathode material.

[0053] Example 3

[0054] This embodiment provides a method for preparing a coated modified lithium nickel cobalt manganese oxide cathode material, the specific steps of which are as follows:

[0055] 1) Obtaining lithium nickel cobalt manganese oxide matrix material: Following the lithium nickel cobalt manganese oxide matrix material LiNi 0.55 Co 0.25 Mn 0.2 Nickel sulfate (NiSO4·6H2O), cobalt sulfate (CoSO4·7H2O), and manganese sulfate (MnSO4·H2O) were weighed out in stoichiometric proportions and mixed with deionized water to form a mixed solution. Ethylenediaminetetraacetic acid (EDTA) was added to the mixed solution as a complexing agent, and the pH of the system was adjusted to 10 using sodium hydroxide aqueous solution. The system temperature was controlled at 80℃ for 4 hours to obtain a precursor. The precursor was dried at 100℃ for 24 hours, then lithium hydroxide (LiOH·H2O) was added and mixed thoroughly. The mixture was then calcined in oxygen at 800℃ for 6 hours to obtain a lithium nickel cobalt manganese oxide matrix material. The mass ratio of nickel sulfate, cobalt sulfate, and manganese sulfate to deionized water and EDTA was 1:0.8:0.4.

[0056] 2) Obtaining the coating material: 3g of alumina powder (particle size 0.3-2μm) and 2g of titanium dioxide powder (particle size 30nm) were added to 200mL of ethanol and ultrasonically dispersed for 60min to form a uniform suspension. 4g of pyrrole monomer and 2g of ammonium persulfate (initiator) were added to the suspension and stirred at room temperature for 5h to carry out the polymerization reaction to obtain the coating material.

[0057] 3) Coating treatment: Transfer all the coating material obtained in step 2) to a ball mill and add 20g of the lithium nickel cobalt manganese oxide matrix material obtained in step 1). Ball mill at 500 rpm for 4 hours to make the coating material uniformly coat the surface of the matrix material. Dry the ball-milled product at 100℃ for 24 hours to obtain the coated modified lithium nickel cobalt manganese oxide cathode material.

[0058] Example 4

[0059] This embodiment provides a method for preparing a coated modified lithium nickel cobalt manganese oxide cathode material. The difference between this method and Example 1 is that step 2) is as follows: 2.286g of alumina powder and 0.571g of titanium dioxide powder are added to 100mL of ethanol and ultrasonically dispersed for 30min to form a uniform suspension. 1.143g of pyrrole monomer and 0.57g of ammonium persulfate are added to the suspension and stirred at room temperature for 3h to carry out a polymerization reaction to obtain the coated material. That is, the mass ratio of alumina powder, titanium dioxide powder and pyrrole monomer is 4:1:2. Other conditions are the same as in Example 1.

[0060] Example 5

[0061] This embodiment provides a method for preparing a coated modified lithium nickel cobalt manganese oxide cathode material. The difference between this method and Example 1 is that in step 3), the mass of the added lithium nickel cobalt manganese oxide matrix material is 7g, that is, the ratio of the total mass of alumina powder and titanium oxide powder in the coating material to the mass of the lithium nickel cobalt manganese oxide matrix material is 1:2; other conditions are the same as in Example 1.

[0062] Example 6

[0063] This embodiment provides a method for preparing a coated modified lithium nickel cobalt manganese oxide cathode material. The difference between this method and Example 1 is that in step 1), the system temperature during co-precipitation with the addition of the complexing agent is 40°C, and the calcination temperature is 500°C; other conditions are the same as in Example 1.

[0064] Comparative Example 1

[0065] This comparative example provides a method for preparing lithium nickel cobalt manganese oxide cathode material. The difference between this method and Example 1 is that it only includes step 1) without subsequent coating treatment, while other conditions are the same as in Example 1.

[0066] Comparative Example 2

[0067] This comparative example provides a method for preparing a coated modified lithium nickel cobalt manganese oxide cathode material. The difference between this method and Example 2 is that step 2) involves adding 3g of pyrrole monomer and 1.5g of ammonium persulfate to 150mL of acetone and stirring at room temperature for 4 hours to polymerize the pyrrole monomer and obtain the coated material. Step 3) involves adding 15g of matrix material to a polypyrrole solution and ball milling it at 400 rpm for 3 hours to coat the surface of the matrix material with polypyrrole. The ball-milled product is then dried at 90°C for 18 hours to obtain the coated modified lithium nickel cobalt manganese oxide cathode material. That is, the coating layer consists only of polypyrrole, and other conditions are the same as in Example 1.

[0068] Comparative Example 3

[0069] This comparative example provides a method for preparing a coated modified lithium nickel cobalt manganese oxide cathode material. The difference between this method and Example 1 is that the alumina powder is replaced with the same mass of titanium oxide powder, that is, 2g of titanium oxide powder and 2g of pyrrole monomer are used as the coating layer, and other conditions are the same as in Example 1.

[0070] Comparative Example 4

[0071] This comparative example provides a method for preparing a coated modified lithium nickel cobalt manganese oxide cathode material. The difference between this method and Example 1 is that the titanium oxide powder is replaced with the same mass of alumina powder, that is, 2g of alumina powder and 2g of pyrrole monomer are used as the coating layer, and other conditions are the same as in Example 1.

[0072] Comparative Example 5

[0073] This comparative example provides a method for preparing a coated modified lithium nickel cobalt manganese oxide cathode material. The difference between this method and Example 1 is that step 2) is as follows: 2g of alumina powder and 2g of titanium oxide powder are added to 100mL of ethanol and ultrasonically dispersed for 30min to obtain the coated material; that is, no pyrrole monomer is added, and other conditions are the same as in Example 1.

[0074] Comparative Example 6

[0075] This comparative example provides a method for preparing a coated modified lithium nickel cobalt manganese oxide cathode material. The difference between this method and Example 1 is that aluminum oxide is replaced with the same mass of magnesium oxide, while other conditions are the same as in Example 1.

[0076] Comparative Example 7

[0077] This comparative example provides a method for preparing a coated modified lithium nickel cobalt manganese oxide cathode material. The difference between this method and Example 1 is that alumina, titanium dioxide, and pyrrole monomers are directly polymerized on the surface of the lithium nickel cobalt manganese oxide matrix material (preparation steps are the same as in Example 1). The specific steps are as follows: 1g of alumina powder, 1g of titanium dioxide powder, and 10g of matrix material are added to 300mL of ethanol and ultrasonically dispersed for 30min to form a uniform suspension. 2g of pyrrole monomer and 1g of ammonium persulfate (initiator) are added to the suspension and stirred at room temperature for 3h to carry out the polymerization reaction. Then, the mixture is dried at 80℃ for 24h to obtain the coated modified lithium nickel cobalt manganese oxide cathode material. Other conditions are the same as in Example 1.

[0078] Test Example 1

[0079] Electrochemical performance tests were conducted on the cathode materials prepared in the above embodiments and comparative examples. The electrochemical performance test steps were as follows: cathode material, carbon black, and polyvinylidene fluoride (PVDF) were weighed and mixed at a mass ratio of 95:2.5:2.5. N-methylpyrrolidone (NMP) solvent was added at a solid-liquid ratio of 2:1 to prepare a cathode slurry. The slurry was uniformly coated onto aluminum foil and vacuum dried at 120°C for 12 hours. The dried electrode sheet was then cut and compacted in a tablet press (compacted density of 3.2 g / cm³). 3 Small circular pieces were cut out to serve as the positive electrode of the lithium-ion battery; lithium metal sheets were used as the negative electrode, and a mixed solution of ethylene carbonate (EC) and diethyl carbonate (DEC) in 1 mol / L LiPF6 (volume ratio 1:1) was used as the electrolyte. CR2032 button batteries were assembled in an argon-atmosphere glove box. Charge-discharge, cycle performance, and rate performance tests were conducted on these batteries. The charge-discharge regime was as follows: charging cut-off voltage was 4.3V, and discharging cut-off voltage was 3.0V; the first cycle was 0.2C charge and 0.2C discharge; the second cycle was 1C charge and 1C discharge; subsequently, 50 cycles of 1C charge and 1C discharge were performed to test the cycle retention rate. The test results are shown in Table 1 below. The cycle curves of the positive electrode materials prepared in Examples 1, 2, 3, and Comparative Examples 6 and 7 are shown below. Figure 1 As shown.

[0080] Table 1

[0081]

[0082] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a coated and modified lithium nickel cobalt manganese oxide cathode material, characterized in that, include: Obtain lithium nickel cobalt manganese oxide matrix material; The coating material was obtained by in-situ polymerization of conductive polymer monomers on the surfaces of alumina powder and titanium dioxide powder. The coated modified lithium nickel cobalt manganese oxide cathode material is prepared by coating the surface of the lithium nickel cobalt manganese oxide matrix material with the coating material and then drying it.

2. The preparation method according to claim 1, characterized in that, The mass ratio of the alumina powder, titanium oxide powder and conductive polymer monomer is (1-3):(1-2):(2-5).

3. The preparation method according to claim 1 or 2, characterized in that, The chemical formula of the lithium nickel cobalt manganese oxide matrix material is LiNi x Co y Mn z O2; where 0.5≤x≤0.8, 0.1≤y≤0.3, 0.1<z≤0.3, and x+y+z=1.

4. The preparation method according to any one of claims 1-3, characterized in that, The ratio of the total mass of alumina powder and titanium oxide powder in the coating material to the mass of lithium nickel cobalt manganese oxide matrix material is 1:(4-5); And / or, the conductive polymer monomer is a pyrrole monomer; And / or, the coating method is ball milling, and the ball milling process parameters are preferably ball milling at a speed of 300-500 rpm for 2-4 hours.

5. The preparation method according to any one of claims 1-4, characterized in that, The in-situ polymerization process is as follows: alumina powder and titanium dioxide powder are added to an organic solvent and ultrasonically dispersed to form a uniform suspension. Conductive polymer monomers and initiators are added to the suspension to carry out a polymerization reaction to obtain the coating material.

6. The preparation method according to claim 5, characterized in that, The mass ratio of the conductive polymer monomer to the initiator is (1-3):1; And / or, based on 100 mL of organic solvent, the total mass of the alumina powder and titanium dioxide powder is 2-3 g; And / or, the polymerization reaction is carried out at room temperature for 3-5 hours; And / or, the organic solvent is ethanol and / or acetone; And / or, the initiator is ammonium persulfate.

7. The preparation method according to any one of claims 1-6, characterized in that, The process for obtaining the lithium nickel cobalt manganese oxide matrix material is as follows: According to the stoichiometric ratio of lithium nickel cobalt manganese oxide matrix material, nickel source, cobalt source, and manganese source are weighed and mixed with water to form a mixed solution; A complexing agent was added to the mixed solution and the pH of the system was adjusted to 8-10 using a pH adjuster. At the same time, the system temperature was controlled at 60-80℃ for 2-4 hours to obtain the precursor. The precursor is dried, then a lithium source is added and mixed, and then calcined in an oxygen-containing atmosphere at 600-800℃ for 4-10 hours to obtain lithium nickel cobalt manganese oxide matrix material.

8. The preparation method according to claim 7, characterized in that, The nickel source includes at least one of nickel sulfate and nickel nitrate; And / or, the cobalt source includes at least one of cobalt sulfate and cobalt nitrate; And / or, the manganese source includes at least one of manganese sulfate and manganese nitrate; And / or, the lithium source includes at least one of lithium carbonate and lithium hydroxide; And / or, the complexing agent includes at least one of ethylenediaminetetraacetic acid and citric acid; And / or, the pH adjuster comprises an aqueous solution of sodium hydroxide; And / or, during the acquisition of the lithium nickel cobalt manganese oxide matrix material, the ratio of the total mass of the nickel source, cobalt source and manganese source to the mass of water and complexing agent is 1:(0.1-1.0):(0-0.5).

9. A coated and modified lithium nickel cobalt manganese oxide cathode material, characterized in that, It is prepared by the method for preparing the coated modified lithium nickel cobalt manganese oxide cathode material according to any one of claims 1-8.

10. A lithium-ion battery, characterized in that, It comprises the coated modified lithium nickel cobalt manganese oxide cathode material as described in claim 9.

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