Ternary positive electrode material, and preparation method therefor and use thereof

Abstract

A ternary positive electrode material, and a preparation method therefor and a use thereof. The preparation method for the ternary positive electrode material comprises the following steps: (1) mixing a ternary precursor and a lithium source, and carrying out first-stage sintering treatment to obtain a first-stage sintered material; and (2) crushing the first-stage sintered material obtained in step (1), mixing the crushed first-stage sintered material with titanium dioxide, carrying out second-stage sintering treatment on a mixture of the first-stage sintered material and the titanium dioxide under illumination, and oxidizing divalent nickel into trivalent nickel to obtain the ternary positive electrode material. In the preparation process of the ternary positive electrode material, divalent nickel can be oxidized into trivalent nickel under the assistance of illumination while trivalent nickel is inhibited from being converted into divalent nickel, thereby reducing the nickel-lithium mixed arrangement of the material.

Description

A ternary positive electrode material and its preparation method and application Technical Field

[0001] The present invention belongs to the technical field of lithium-ion batteries and relates to a ternary positive electrode material and a preparation method and application thereof. Background Art

[0002] With the increasing depletion of fossil fuels like coal, natural gas, and oil, renewable resources and environmental issues have become a major concern worldwide, leading to the emergence of new energy vehicles. As a core component of new energy vehicles, new energy batteries urgently need rapid development to meet the urgent demand for their practical applications. Lithium nickel cobalt manganese oxide, a key cathode material for lithium-ion batteries, boasts a high discharge capacity and is the most promising cathode material for lithium-ion batteries.

[0003] At present, lithium nickel cobalt manganese oxide cathode materials have not been widely used commercially, mainly because of their poor cycle stability and rate performance. The main reason for the poor cycle stability is that Ni 2+ It is difficult to be completely oxidized to Ni during the synthesis of ternary cathode materials. 3+ , the residual Ni 2+ The radius of the ion is similar to that of Li+, so Li+ will occur during the charge and discharge cycle. + / Ni 2+ Mixing causes changes in the structure of lithium nickel cobalt manganese oxide, thus affecting the cycle stability.

[0004] CN114975915A discloses a high-nickel NCM ternary positive electrode material with surface coating of ZnO and Li2ZnO2 and its application. By coating ZnO and Li2ZnO2 on the surface of the high-nickel ternary positive electrode material, the residual alkali and inherent rock salt phase on the surface of the material are removed. However, the nickel-lithium mixed arrangement of the positive electrode material is relatively high, which affects the performance of the material.

[0005] CN108777291A uses a strong oxidizing acid anhydride to mix with the precursor and mill it so that the precursor powder is pre-oxidized, thereby reducing the nickel-lithium mixing and improving the reversible capacity of the battery. + / Ni 2+ Mixed, but simple coating is difficult to improve Ni in the synthesis process 3+ The content of Ni 3+ content, but it is difficult to inhibit Ni in the subsequent synthesis 3+ To you 2+ The nickel-lithium mixed arrangement cannot be further reduced.

[0006] The above schemes reduce the nickel-lithium mixing by simply coating or preparing hydroxide oxides, but it is difficult to inhibit the Ni in the subsequent synthesis. 3+ To you 2+ The effect of reducing nickel-lithium mixed discharge is poor.

[0007] Summary of the Invention

[0008] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0009] The purpose of the present disclosure is to provide a ternary positive electrode material and its preparation method and application. In the preparation process of the ternary positive electrode material, the present disclosure can oxidize divalent nickel into trivalent nickel with the aid of light, while inhibiting the conversion of trivalent nickel into divalent nickel, thereby reducing the nickel-lithium mixed arrangement of the material.

[0010] To achieve this disclosure purpose, the present disclosure adopts the following technical solutions:

[0011] In a first aspect, an embodiment of the present disclosure provides a method for preparing a ternary cathode material, the method comprising the following steps:

[0012] (1) After mixing the ternary precursor, titanium source and lithium source, a sintering process is performed to obtain a sintered material;

[0013] (2) After crushing the calcined material obtained in step (1), the crushed calcined material is mixed with titanium dioxide, and the calcined material obtained in step (1) is subjected to a two-stage sintering process under light to obtain the ternary positive electrode material.

[0014] In the preparation process of the ternary positive electrode material of the embodiment of the present disclosure, the Ni inside the material is crushed after the sintered material is crushed. 2+ Expose to the surface of the material, add titanium dioxide during the second firing process, titanium dioxide is evenly coated on the surface of the material, and light is used to assist in the second firing process, which can make Ni 2+ Better oxidation to Ni 3+ , and can also inhibit Ni 3+ During the synthesis process, it is converted into Ni 2+ , improving the electrochemical performance of the material and reducing the lithium-nickel mixing caused by incomplete nickel ion oxidation and nickel ion conversion. At the same time, the titanium dioxide coating on the surface of the prepared ternary positive electrode material reduces the direct contact between the positive electrode material and the electrolyte, reduces the adverse reactions between the two, and improves the cycle stability of the positive electrode material.

[0015] In one embodiment, the ternary precursor in step (1) includes a ternary nickel-cobalt-manganese precursor.

[0016] In the two-stage sintering described in the embodiment of the present disclosure, the ionic equation of the light irradiation reaction is as follows:

[0017] In one embodiment, the lithium source includes lithium hydroxide and / or lithium carbonate.

[0018] In one embodiment, the molar ratio of the lithium element in the lithium source in step (1) to the total metal elements in the ternary precursor is (1.01-1.05):1, for example: 1.01:1, 1.02:1, 1.03:1, 1.04:1 or 1.05:1, etc.

[0019] In one embodiment, the temperature of the sintering treatment in step (1) is 450-600°C, for example, 450°C, 480°C, 500°C, 550°C or 600°C.

[0020] In one embodiment, the sintering treatment time is 3 to 8 hours, for example, 3 hours, 4 hours, 5 hours, 7 hours or 8 hours.

[0021] In one embodiment, the mass ratio of the calcined material to titanium dioxide in step (2) is 100:(0.2-1), for example: 100:0.2, 100:0.4, 100:0.6, 100:0.8 or 100:1, etc.

[0022] In one embodiment, the intensity of the light in step (2) is 12 to 36 mW / cm 2 , for example: 12mW / cm 2 , 15mW / cm 2 , 20mW / cm 2 , 25mW / cm 2 、30mW / cm 2 or 36mW / cm 2 wait.

[0023] In one embodiment, the wavelength of the light is 200-380 nm, for example, 200 nm, 250 nm, 300 nm, 350 nm or 380 nm.

[0024] In one embodiment, the temperature of the second-stage sintering treatment in step (2) is 600-1000°C, for example, 600°C, 700°C, 800°C, 900°C or 1000°C.

[0025] In one embodiment, the second-stage sintering treatment lasts for 5 to 12 hours, for example, 5 hours, 6 hours, 8 hours, 10 hours, or 12 hours.

[0026] In one embodiment, the apparatus for the second-stage sintering process includes a rotary kiln.

[0027] The two-stage sintering process described in the embodiment of the present disclosure uses a rotary kiln. During the sintering process, the titanium dioxide and the crushed first-fired material are continuously rolled, which can carry out the photocatalytic reaction better and more evenly, and the obtained titanium dioxide coating layer is more uniform.

[0028] As an optional solution of the embodiment of the present disclosure, the preparation method includes the following steps:

[0029] (1) After mixing the ternary precursor and the lithium source, sintering at 450-600°C for 3-8h to obtain a sintered material;

[0030] (2) After crushing the calcined material obtained in step (1), the crushed calcined material is mixed with titanium dioxide in a mass ratio of 100:(0.2-1), and the mixture is heated at a wavelength of 200-380 nm and an intensity of 12-36 mW / cm 2 The ternary positive electrode material is obtained by sintering at 600-900° C. for 5-12 hours under light.

[0031] In a second aspect, an embodiment of the present disclosure provides a ternary positive electrode material, which is prepared by the method described in the first aspect. The ternary positive electrode material includes a core and a titanium dioxide coating layer arranged on the surface of the core, and the titanium dioxide coating layer is anatase-type titanium dioxide.

[0032] In a third aspect, an embodiment of the present disclosure provides a positive electrode plate, which comprises the ternary positive electrode material as described in the second aspect.

[0033] In a fourth aspect, an embodiment of the present disclosure provides a lithium-ion battery, wherein the lithium-ion battery comprises the positive electrode sheet as described in the third aspect.

[0034] The present disclosure has the following beneficial effects:

[0035] (1) In the preparation process of the ternary positive electrode material, the present invention discloses that the divalent nickel can be oxidized into trivalent nickel by light, and the conversion of trivalent nickel into divalent nickel can be suppressed, thereby reducing the nickel-lithium mixed arrangement of the material. Titanium dioxide is directly used as the titanium source. During the sintering process, the light can be irradiated to make Ni 2+ Better oxidation to Ni 3+ .

[0036] (2) The method disclosed in the present invention can produce a ternary positive electrode material, and the first discharge capacity of the NCM622 type battery can reach more than 178.04mAh / g, and the discharge capacity after 100 cycles can reach more than 176mAh / g, and the capacity retention rate can reach more than 98.85%. The first discharge capacity of the NCM811 type battery can reach 213.54mAh / g, and the discharge capacity after 100 cycles can reach 209.18mAh / g, and the capacity retention rate can reach 97.96%. The first discharge capacity of the NCM523 type battery can reach 168.24mAh / g, and the discharge capacity after 100 cycles can reach 166.41mAh / g, and the capacity retention rate can reach 98.91%, showing good electrochemical performance.

[0037] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings are used to provide a further understanding of the technical solution of this article and constitute a part of the specification. Together with the embodiments of this application, they are used to explain the technical solution of this article and do not constitute a limitation on the technical solution of this article.

[0039] FIG1 is a SEM image of the ternary positive electrode material described in Example 1 of the present disclosure. DETAILED DESCRIPTION

[0040] The technical solution of the present disclosure is further described below through specific implementation methods. Those skilled in the art should understand that the embodiments are only used to help understand the present disclosure and should not be regarded as specific limitations of the present disclosure.

[0041] The ternary precursors used in the examples and comparative examples of the present disclosure were prepared by the following method:

[0042] Example 1

[0043] This embodiment provides a ternary positive electrode material, and the preparation method of the ternary positive electrode material is as follows:

[0044] (1) nickel chloride, cobalt chloride and manganese chloride are mixed and dissolved in water to obtain solution A, wherein the concentration of solution A is 2 mol / L, wherein the molar ratio of Ni:Co:Mn elements is 6:2:2, precipitant solution B and complexing agent solution C are added to solution A, mixed and stirred for 2 hours and then aged for 12 hours, wherein the precipitant solution is sodium hydroxide solution with a concentration of 4 mol / L, and the complexing agent is ammonia solution with a concentration of 4 mol / L, and the volume ratio of solution A to solution B and solution C is 2:3:0.8. After aging, the solution is filtered, washed and dried to obtain a ternary precursor;

[0045] (2) mixing lithium hydroxide as a ternary precursor, wherein the ratio of the molar amount of lithium element in the lithium hydroxide to the total molar amount of nickel, cobalt and manganese metals in the ternary precursor is 1.02:1, and sintering at 500° C. for 6 hours to obtain a single-fired material;

[0046] (3) After crushing the calcined material obtained in step (1), the crushed calcined material was mixed with titanium dioxide in a mass ratio of 100:0.5, and the mixture was heated at a wavelength of 280 nm and an intensity of 20 mW / cm 2 The ternary positive electrode material was obtained by sintering at 750° C. for 8 h in a rotary kiln under illumination of .

[0047] The SEM image of the ternary cathode material is shown in FIG1 .

[0048] Example 2

[0049] This embodiment provides a ternary positive electrode material, and the preparation method of the ternary positive electrode material is as follows:

[0050] (1) nickel chloride, cobalt chloride and manganese chloride are mixed and dissolved in water to obtain solution A, wherein the concentration of solution A is 2 mol / L, wherein the molar ratio of Ni:Co:Mn elements is 8:1:1, precipitant solution B and complexing agent solution C are added to solution A, mixed and stirred for 2 hours and then aged for 12 hours, wherein the precipitant solution is sodium hydroxide solution with a concentration of 4 mol / L, and the complexing agent is ammonia solution with a concentration of 4 mol / L, and the volume ratio of solution A to solution B and solution C is 2:3:0.8. After aging, the solution is filtered, washed and dried to obtain a ternary precursor;

[0051] (2) mixing lithium hydroxide as a ternary precursor, wherein the ratio of the molar amount of lithium element in the lithium hydroxide to the total molar amount of nickel, cobalt and manganese metals in the ternary precursor is 1.02:1, and sintering the mixture at 500° C. for 6 hours to obtain a single-fired material;

[0052] (3) After the calcined material obtained in step (1) is crushed, the crushed calcined material is mixed with titanium dioxide in a mass ratio of 100:0.2, and the mixture is heated at a wavelength of 280 nm and an intensity of 36 mW / cm 2 The ternary positive electrode material was obtained by sintering at 750° C. for 8 h in a rotary kiln under illumination of .

[0053] Example 3

[0054] This embodiment provides a ternary positive electrode material, and the preparation method of the ternary positive electrode material is as follows:

[0055] (1) nickel chloride, cobalt chloride and manganese chloride are mixed and dissolved in water to obtain solution A, wherein the concentration of solution A is 2 mol / L, wherein the molar ratio of Ni:Co:Mn elements is 5:2:3, precipitant solution B and complexing agent solution C are added to solution A, mixed and stirred for 2 hours and then aged for 12 hours, wherein the precipitant solution is sodium hydroxide solution with a concentration of 4 mol / L, and the complexing agent is ammonia solution with a concentration of 4 mol / L, and the volume ratio of solution A to solution B and solution C is 2:3:0.8. After aging, the solution is filtered, washed and dried to obtain a ternary precursor;

[0056] (2) mixing the ternary precursor and lithium hydroxide, wherein the ratio of the molar amount of lithium element in the lithium hydroxide to the total molar amount of nickel, cobalt and manganese metals in the ternary precursor is 1.02:1, and sintering the mixture at 500° C. for 6 hours to obtain a single-fired material;

[0057] (3) After the calcined material obtained in step (1) is crushed, the crushed calcined material is mixed with titanium dioxide in a mass ratio of 100:1, and the mixture is heated at a wavelength of 280 nm and an intensity of 12 mW / cm 2 The ternary positive electrode material was obtained by sintering at 750° C. for 8 h in a rotary kiln under illumination of .

[0058] Example 4

[0059] This embodiment provides a ternary positive electrode material, and the preparation method of the ternary positive electrode material is as follows:

[0060] (1) nickel chloride, cobalt chloride and manganese chloride are mixed and dissolved in water to obtain solution A, wherein the concentration of solution A is 2 mol / L, wherein the molar ratio of Ni:Co:Mn elements is 6:2:2, precipitant solution B and complexing agent solution C are added to solution A, mixed and stirred for 2 hours and then aged for 12 hours, wherein the precipitant solution is sodium hydroxide solution with a concentration of 4 mol / L, and the complexing agent is ammonia solution with a concentration of 4 mol / L, and the volume ratio of solution A to solution B and solution C is 2:3:0.8. After aging, the solution is filtered, washed and dried to obtain a ternary precursor;

[0061] (2) mixing the ternary precursor and lithium hydroxide, wherein the ratio of the molar amount of lithium element in the lithium hydroxide to the total molar amount of nickel, cobalt and manganese metals in the ternary precursor is 1.02:1, and sintering the mixture at 450° C. for 6.2 h to obtain a single-fired material;

[0062] (3) After crushing the calcined material obtained in step (1), the crushed calcined material was mixed with titanium dioxide in a mass ratio of 100:0.6, and the mixture was heated at a wavelength of 300 nm and an intensity of 22 mW / cm 2 The mixture was sintered in a rotary kiln at 760° C. for 8 h under illumination to obtain the ternary positive electrode material.

[0063] Example 5

[0064] This embodiment provides a ternary positive electrode material, and the preparation method of the ternary positive electrode material is as follows:

[0065] (1) nickel chloride, cobalt chloride and manganese chloride are mixed and dissolved in water to obtain solution A, wherein the concentration of solution A is 2 mol / L, wherein the molar ratio of Ni:Co:Mn elements is 6:2:2, precipitant solution B and complexing agent solution C are added to solution A, mixed and stirred for 2 hours and then aged for 12 hours, wherein the precipitant solution is sodium hydroxide solution with a concentration of 4 mol / L, and the complexing agent is ammonia solution with a concentration of 4 mol / L, and the volume ratio of solution A to solution B and solution C is 2:3:0.8. After aging, the solution is filtered, washed and dried to obtain a ternary precursor;

[0066] (2) mixing the ternary precursor and lithium hydroxide, wherein the ratio of the molar amount of lithium element in the lithium hydroxide to the total molar amount of nickel, cobalt and manganese metals in the ternary precursor is 1.02:1, and sintering the mixture at 500° C. for 6 hours to obtain a single-fired material;

[0067] (3) After the calcined material obtained in step (1) is crushed, the crushed calcined material is mixed with titanium dioxide in a mass ratio of 100:0.5, and the mixture is heated at a wavelength of 280 nm and an intensity of 5 mW / cm 2 The mixture is sintered in a rotary kiln at 750° C. for 8 hours under light to obtain the ternary positive electrode material.

[0068] Example 6

[0069] This embodiment provides a ternary positive electrode material, and the preparation method of the ternary positive electrode material is as follows:

[0070] (1) nickel chloride, cobalt chloride and manganese chloride are mixed and dissolved in water to obtain solution A, wherein the concentration of solution A is 2 mol / L, wherein the molar ratio of Ni:Co:Mn elements is 6:2:2, precipitant solution B and complexing agent solution C are added to solution A, mixed and stirred for 2 hours and then aged for 12 hours, wherein the precipitant solution is sodium hydroxide solution with a concentration of 4 mol / L, and the complexing agent is ammonia solution with a concentration of 4 mol / L, and the volume ratio of solution A to solution B and solution C is 2:3:0.8. After aging, the solution is filtered, washed and dried to obtain a ternary precursor;

[0071] (2) mixing the ternary precursor and lithium hydroxide, wherein the ratio of the molar amount of lithium element in the lithium hydroxide to the total molar amount of nickel, cobalt and manganese metals in the ternary precursor is 1.02:1, and sintering the mixture at 500° C. for 6 hours to obtain a single-fired material;

[0072] (3) After crushing the calcined material obtained in step (1), the crushed calcined material was mixed with titanium dioxide in a mass ratio of 100:0.5, and the mixture was heated at a wavelength of 300 nm and an intensity of 50 mW / cm 2 The mixture is sintered in a rotary kiln at 750° C. for 8 hours under light to obtain the ternary positive electrode material.

[0073] Example 7

[0074] This embodiment provides a ternary positive electrode material, and the preparation method of the ternary positive electrode material is as follows:

[0075] (1) nickel chloride, cobalt chloride and manganese chloride are mixed and dissolved in water to obtain solution A, wherein the concentration of solution A is 2 mol / L, wherein the molar ratio of Ni:Co:Mn elements is 6:2:2, precipitant solution B and complexing agent solution C are added to solution A, mixed and stirred for 2 hours and then aged for 12 hours, wherein the precipitant solution is sodium hydroxide solution with a concentration of 4 mol / L, and the complexing agent is ammonia solution with a concentration of 4 mol / L, and the volume ratio of solution A to solution B and solution C is 2:3:0.8. After aging, the solution is filtered, washed and dried to obtain a ternary precursor;

[0076] (2) mixing the ternary precursor and lithium hydroxide, wherein the ratio of the molar amount of lithium element in the lithium hydroxide to the total molar amount of nickel, cobalt and manganese metals in the ternary precursor is 1.02:1, and sintering the mixture at 500° C. for 6 hours to obtain a single-fired material;

[0077] (3) After the calcined material obtained in step (1) is crushed, the crushed calcined material is mixed with titanium dioxide in a mass ratio of 100:0.5, and the mixture is heated at a wavelength of 300 nm and an intensity of 20 mW / cm 2 The mixture is sintered in a rotary kiln at 1100° C. for 8 hours under light to obtain the ternary positive electrode material.

[0078] Comparative Example 1

[0079] The only difference between this comparative example and Example 1 is that the second-stage sintering is not subjected to light treatment, and the other conditions and parameters are exactly the same as those in Example 1.

[0080] Performance testing:

[0081] The positive electrode materials obtained in Examples 1-7 and Comparative Example 1 were prepared into a slurry with a mass ratio of positive electrode material: conductive carbon black: PVDF: N-methylpyrrolidone of 90:5:5:40. The slurry was coated onto an aluminum foil sheet, vacuum dried, and then roll-pressed to produce a positive electrode sheet. Coin-type batteries were assembled using the positive electrode sheet as the positive electrode and the lithium sheet as the negative electrode. The charge and discharge voltage was set at 3.0-4.3V, and the initial capacity and cycle performance of the battery were tested at 1C. The test results are shown in Table 1:

[0082] Table 1

[0083] As can be seen from Table 1, it can be obtained from Examples 1-4 that the first discharge specific capacity of the NCM622 battery prepared by the ternary positive electrode material according to the method of the present invention can reach more than 178.04 mAh / g, and the discharge specific capacity after 100 cycles can reach more than 176 mAh / g, and the capacity retention rate can reach more than 98.85%. The first discharge specific capacity of the NCM811 battery can reach 213.54 mAh / g, and the discharge specific capacity after 100 cycles can reach 209.18 mAh / g, and the capacity retention rate can reach 97.96%. The first discharge specific capacity of the NCM523 battery can reach 168.24 mAh / g, and the discharge specific capacity after 100 cycles can reach 166.41 mAh / g, and the capacity retention rate can reach 98.91%, showing good electrochemical performance.

[0084] From the comparison between Example 1 and Examples 5-6, it can be seen that in the preparation process of the ternary cathode material disclosed in the present invention, the illumination intensity of the second stage sintering will affect the performance of the ternary cathode material. The illumination intensity is controlled at 12-36 mW / cm 2 The performance of the positive electrode material is better. If the light intensity is too high, it may stimulate other side reactions of titanium dioxide. If the light intensity is too low, it will reduce the reaction rate of hole generation.

[0085] From the comparison between Example 1 and Example 7, it can be seen that the temperature of the second-stage sintering described in the present disclosure needs to be controlled within 900°C. If the sintering temperature is too high, most of the anatase titanium dioxide will be transformed into rutile titanium dioxide, and the photocatalytic performance will be reduced.

[0086] From the comparison between Example 1 and Comparative Example 1, it can be seen that in the preparation process of the ternary positive electrode material, the present invention adopts light assistance to make Ni 2+ Better oxidation to Ni 3+ , and can also inhibit Ni 3+ Converted to Ni during the synthesis 2+ , improving the electrochemical performance of the material and reducing the lithium-nickel mixing caused by incomplete nickel ion oxidation and nickel ion conversion. At the same time, the titanium dioxide coating on the surface of the prepared ternary positive electrode material reduces the direct contact between the positive electrode material and the electrolyte, reduces the adverse reactions between the two, and improves the cycle stability of the positive electrode material.

Claims

1. A method for preparing a ternary positive electrode material, the preparation method comprising the following steps: (1) After mixing the ternary precursor and the lithium source, a sintering treatment is performed to obtain a sintered material; (2) After crushing the calcined material obtained in step (1), the crushed calcined material is mixed with titanium dioxide, and subjected to a two-stage sintering treatment under light to obtain the ternary positive electrode material.

2. The preparation method according to claim 1, wherein The ternary precursor in step (1) includes a ternary nickel-cobalt-manganese precursor.

3. The preparation method according to claim 1 or 2, wherein: The lithium source includes lithium hydroxide and / or lithium carbonate.

4. The preparation method according to any one of claims 1 to 3, wherein The molar ratio of the lithium element in the lithium source in step (1) to the total metal elements in the ternary precursor is (1.01-1.05):

1.

5. The preparation method according to any one of claims 1 to 4, wherein: The temperature of the sintering treatment in step (1) is 450-600°C.

6. The preparation method according to any one of claims 1 to 5, wherein: The time of the sintering treatment is 3 to 8 hours.

7. The preparation method according to any one of claims 1 to 6, wherein: The mass ratio of the calcined material to titanium dioxide in step (2) is 100:(0.2-1); The intensity of the light is 12-36 mW / cm 2 .

8. The preparation method according to any one of claims 1 to 7, wherein: The wavelength of the light is 200-380 nm.

9. The preparation method according to any one of claims 1 to 8, wherein: The temperature of the second-stage sintering treatment in step (2) is 600-1000°C.

10. The preparation method according to any one of claims 1 to 9, wherein: The time of the second stage sintering treatment is 5 to 12 hours.

11. The preparation method according to any one of claims 1 to 10, wherein: The device for the second-stage sintering process includes a rotary kiln.

12. The preparation method according to any one of claims 1 to 11, wherein: The preparation method comprises the following steps: (1) After mixing the ternary precursor and the lithium source, sintering at 450-600° C. for 3-8 hours to obtain a sintered material; (2) After the calcined material obtained in step (1) is crushed, the crushed calcined material is mixed with titanium dioxide in a mass ratio of 100:(0.2-1), and the wavelength is 200-380nm and the intensity is 12-36mW / cm 2 The ternary positive electrode material is obtained by sintering at 600-900° C. for 5-12 hours under light.

13. A ternary positive electrode material, which is prepared by the method according to any one of claims 1 to 12, and comprises a core and a titanium dioxide coating layer arranged on the surface of the core, and the titanium dioxide coating layer is anatase titanium dioxide.

14. A positive electrode sheet, wherein: The positive electrode sheet comprises the ternary positive electrode material as claimed in claim 13.

15. A lithium ion battery, wherein: The lithium-ion battery comprises the positive electrode sheet as claimed in claim 14.

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