High-voltage ternary cathode material and its preparation method

Abstract

The present application provides a high-voltage ternary cathode material and a preparation method thereof. The above-mentioned high-voltage ternary cathode material includes ternary cathode active material particles and a flexible coating, and the flexible coating is coated on the surface of the ternary cathode active material particles. The flexible coating includes a mixture of polyaniline and polyurethane elastomer. The above-mentioned high-voltage ternary cathode material has good cycling performance and high safety performance.

Description

Technical Field

[0001] The present invention relates to the technical field of cathode materials for lithium - ion batteries, and particularly to a high - voltage ternary cathode material and a preparation method thereof. Background Art

[0002] The performance of lithium - ion batteries is closely related to the performance of the electrode materials used. The traditional cathode material lithium cobaltate has a wide discharge window and good cycling characteristics. However, the cobalt content in the cathode material lithium cobaltate is relatively high, which will cause environmental pollution, and it is difficult for the cathode material lithium cobaltate to meet the requirements of high capacity, high energy density and safety performance. In recent years, ternary cathode materials have combined the comprehensive characteristics of three cathode materials: lithium cobalt oxide, lithium nickel oxide and lithium manganese oxide, alleviating the problem of environmental pollution caused by high cobalt content, and realizing the complementarity of the structures and performances of the three materials. With characteristics such as a high capacity greater than 150 mAh / g, good cycling performance, simple synthesis process and environmental friendliness, they have become one of the most promising cathode materials at present.

[0003] However, when the ternary cathode material is charged and discharged under high - voltage and high - temperature conditions, due to the large amount of lithium ions inserted and extracted, the reaction is relatively violent and the anisotropic stress generated is relatively strong, it is easy to cause the ternary cathode material particles to break, which will further lead to more side reactions, and ultimately affect the cycling performance and safety performance of the battery. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a high - voltage ternary cathode material with good cycling performance and high safety performance and a preparation method thereof.

[0005] The purpose of the present invention is achieved by the following technical solutions:

[0006] A high - voltage ternary cathode material includes ternary cathode active material particles and a flexible coating body, and the flexible coating body coats the surface of the ternary cathode active material particles;

[0007] Among them, the flexible coating body includes a mixture of polyaniline and polyurethane elastomer.

[0008] In one embodiment, the ternary cathode active material is Li 1+x Ni a Co b Mn c O2, 1 / 3 ≤ a ≤ 0.8, 0.1 ≤ b ≤ 1 / 3, 0.1 ≤ c ≤ 1 / 3, 0 ≤ x < 0.2, a + b + c = 1.

[0009] In one embodiment, the ternary cathode active material is LiNi 1 / 3 Co1 / 3 Mn 1 / 3 O2, LiNi 0.4 Co 0.2 Mn 0.4 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2 or LiNi 0.8 Co 0.1 Mn 0.1 O2.

[0010] In one embodiment, the polyaniline is phosphotungstic acid-doped modified polyaniline.

[0011] A preparation method of a high-voltage ternary cathode material for preparing the high-voltage ternary cathode material described in any one of the above embodiments, the preparation method of the high-voltage ternary cathode material includes the following steps:

[0012] Obtain a flexible coating;

[0013] Disperse the flexible coating;

[0014] Add a ternary cathode active material to the dispersed flexible coating for coating operation, so that the surface of the ternary cathode active material particles is coated with a flexible coating body, and the high-voltage ternary cathode material is obtained.

[0015] In one embodiment, the obtaining of the flexible coating specifically includes the following steps:

[0016] Obtain aniline;

[0017] Add polyurethane elastomer to the aniline for dispersion and attachment operation, so that the aniline adheres to the polyurethane elastomer to obtain a coating solution;

[0018] Perform in-situ oxidative polymerization on the coating solution to obtain the flexible coating.

[0019] In one embodiment, the mass ratio of the aniline to the polyurethane elastomer is (0.5 - 1.25):1.

[0020] In one embodiment, before the step of adding the polyurethane elastomer to the aniline for dispersion and attachment operation and after the step of obtaining the aniline, the obtaining of the flexible coating specifically further includes the following steps:

[0021] Disperse and mix the aniline with phosphotungstic acid.

[0022] In one embodiment, the mass ratio of the aniline to the phosphotungstic acid is 1:(5-10).

[0023] In one embodiment, H2O2 is used to perform in-situ oxidative polymerization on the coating solution.

[0024] Compared with the prior art, the present invention has at least the following advantages:

[0025] For the high-voltage ternary cathode material of the present invention, the flexible coating body is a mixture of polyaniline and polyurethane elastomer, and is coated on the outer surface of the ternary cathode active material particles, that is, the high-voltage ternary cathode material is multiple ternary cathode active material particles with a mixture of polyaniline and polyurethane elastomer coated on their surfaces. Since the flexible coating body containing the mixture of polyaniline and polyurethane elastomer has both flexibility and conductivity, during the charge and discharge process of the battery containing the high-voltage ternary cathode material, that is, during the process of lithium deintercalation and insertion, the flexible coating body can adapt to the interfacial changes of the ternary cathode active material particles and maintain the interfacial stability and dynamic integrity of the ternary cathode active material particles. At the same time, the flexible coating body can provide a uniform lithium ion transmission interface for the deintercalation and insertion of lithium ions, thereby better reducing the problem that the ternary cathode active material particles are easily broken and cause more side reactions, ultimately affecting the cycle performance and safety performance of the battery, and better improving the cycle performance and safety performance of the battery. Description of the Drawings

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0027] Figure 1 It is a flowchart of the preparation method of the high-voltage ternary cathode material according to an embodiment of the present invention;

[0028] Figure 2 It is an SEM image of the high-voltage ternary cathode material of Example 3;

[0029] Figure 3 It is another SEM image of the high-voltage ternary cathode material of Example 3. Detailed Embodiments

[0030] For the convenience of understanding the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. The preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present invention more thorough and comprehensive.

[0031] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there may also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0033] The present application provides a high-voltage ternary cathode material. The above-mentioned high-voltage ternary cathode material includes ternary cathode active material particles and a flexible coating body, and the flexible coating body is coated on the surface of the ternary cathode active material particles. The flexible coating body includes a mixture of polyaniline and polyurethane elastomer.

[0034] For the above-mentioned high-voltage ternary cathode material, the flexible coating body is a mixture of polyaniline and polyurethane elastomer and is coated on the outer surface of the ternary cathode active material particles, that is, the high-voltage ternary cathode material is multiple ternary cathode active material particles with the outer surface coated with a mixture of polyaniline and polyurethane elastomer. Since the flexible coating body containing the mixture of polyaniline and polyurethane elastomer has both flexibility and conductivity, during the charge and discharge process of the battery containing the high-voltage ternary cathode material, that is, during the process of lithium deintercalation and insertion, the flexible coating body can adapt to the interfacial changes of the ternary cathode active material particles and maintain the interfacial stability and dynamic integrity of the ternary cathode active material particles. At the same time, the flexible coating body can provide a uniform lithium ion transport interface for the deintercalation and insertion of lithium ions, thereby better reducing the problem that the ternary cathode active material particles are easily broken and cause more side reactions, ultimately affecting the cycle performance and safety performance of the battery, and better improving the cycle performance and safety performance of the battery.

[0035] In one embodiment, the mass ratio of the flexible coating to the ternary cathode active material particles is (2 - 8):100, which preferably ensures the sufficient coating of the ternary cathode active material particles, and thus preferably realizes the improvement of the cycling performance and safety performance.

[0036] In one embodiment, the flexible coating includes a plurality of flexible coating monomers. Each flexible coating monomer includes polyurethane elastomer particles and a polyaniline film, and the polyaniline film coats the surface of the polyurethane elastomer particles. The polyurethane elastomer particles of the plurality of flexible coating monomers are uniformly stacked and coated on the surface of the ternary cathode active material particles, which preferably ensures the flexibility and conductivity of the flexible coating, and thus preferably improves the cycling performance and safety performance of the battery.

[0037] In one embodiment, the flexible coating includes a plurality of flexible coating monomers. Each flexible coating monomer includes polyurethane elastomer particles and a phosphotungstic acid-doped modified polyaniline film, and the phosphotungstic acid-doped modified polyaniline film coats the surface of the polyurethane elastomer particles. The polyurethane elastomer particles of the plurality of flexible coating monomers are uniformly stacked and coated on the surface of the ternary cathode active material particles.

[0038] In one embodiment, the polyaniline is phosphotungstic acid-doped modified polyaniline. It can be understood that phosphotungstic acid is a polynuclear complex, which has both the characteristics of a complex and a metal oxide, and also has unique redox properties and strong acidity. It can provide protons to dope with polyaniline to form a doped polymer, that is, form phosphotungstic acid-modified doped polyaniline, and the phosphotungstic acid embedded in the polyaniline matrix still maintains its own structural characteristics. The polyaniline can be polymerized on the surface of the polyurethane elastomer by in-situ oxidative polymerization, and the doping of phosphotungstic acid to polyaniline can be realized in this process. That is, the structure of polyaniline is maintained, and the structure of phosphotungstic acid is also maintained, and the conductivity of the polyaniline doped with phosphotungstic acid is significantly improved. At the same time, due to the protonation effect, the acidity and alkalinity of phosphotungstic acid are effectively adjusted, the acid-base catalytic activity of phosphotungstic acid is reduced, and the influence of phosphotungstic acid on the mechanical properties of the high-voltage ternary cathode material is reduced.

[0039] The present application also provides a preparation method of a high-voltage ternary cathode material. To better understand the preparation method of the high-voltage ternary cathode material of the present application, the following further explains the preparation method of the high-voltage ternary cathode material of the present application:

[0040] One embodiment of the preparation method of the high-voltage ternary cathode material includes some or all of the following steps:

[0041] S100. Obtain a flexible coating. It can be understood that the flexible coating has good flexibility and conductivity. Obtaining the flexible coating to process and coat the ternary cathode active material enables the flexible coating to adapt to the interfacial changes of the ternary cathode active material particles and maintain the interfacial stability and dynamic integrity of the ternary cathode active material particles during the process of lithium deintercalation and intercalation in a battery containing a high-voltage ternary cathode material. At the same time, the flexible coating can provide a uniform lithium-ion transmission interface for the deintercalation and intercalation of lithium ions, thereby better reducing the problem that the ternary cathode active material particles are easily broken, resulting in more side reactions, ultimately affecting the cycle performance and safety performance of the battery, and better improving the cycle performance and safety performance of the battery.

[0042] S200. Disperse the flexible coating. It can be understood that after dispersing the flexible coating first, it is beneficial for the ternary cathode active material to be uniformly mixed in the flexible coating body, thereby better ensuring the further coating effect of the ternary cathode active material.

[0043] S300. Add the ternary cathode active material to the dispersed flexible coating for coating operation so that the surface of the ternary cathode active material particles is coated with a flexible coating body to obtain a high-voltage ternary cathode material. It can be understood that the flexible coating covering the surface of the ternary cathode active material forms a flexible coating body on the surface of the ternary cathode active material. After dispersing the flexible coating, then adding the ternary cathode active material for coating better improves the mixing uniformity of the ternary cathode active material and the flexible coating, thereby better improving the coating effect of the ternary cathode active material, that is, better improving the coating rate of the ternary cathode active material and the particle size uniformity of the high-voltage ternary cathode material.

[0044] For the above method for preparing a high-voltage ternary cathode material, a flexible coating is obtained, and the ternary cathode active material is further added for coating after the flexible coating, so that a flexible coating body is formed on the surface of the ternary cathode active material, which better improves the mixing uniformity of the ternary cathode active material and the flexible coating, thereby better improving the coating rate of the ternary cathode active material and the particle size uniformity of the high-voltage ternary cathode material. And because the flexible coating body has good flexibility and conductivity, during the process of lithium deintercalation and intercalation in a battery containing a high-voltage ternary cathode material, the flexible coating body can adapt to the interfacial changes of the ternary cathode active material particles and maintain the interfacial stability and dynamic integrity of the ternary cathode active material particles. At the same time, the flexible coating body can provide a uniform lithium-ion transmission interface for the deintercalation and intercalation of lithium ions, thereby better reducing the problem that the ternary cathode active material particles are easily broken, resulting in more side reactions, ultimately affecting the cycle performance and safety performance of the battery, and better improving the cycle performance and safety performance of the battery.

[0045] In one embodiment, the ternary cathode active material is Li 1+x Ni a Co b Mn c O2, where 1 / 3 ≤ a ≤ 0.8, 0.1 ≤ b ≤ 1 / 3, 0.1 ≤ c ≤ 1 / 3, 0 ≤ x < 0.2, and a + b + c = 1, which is better adapted to the flexible coating, and thus is beneficial to improving the specific capacity, cycling performance, and safety performance of the high-voltage ternary cathode material.

[0046] In one embodiment, the ternary cathode active material is LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNi 0.4 Co 0.2 Mn 0.4 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, or LiNi 0.8 Co 0.1 Mn 0.1 O2, which is better adapted to the flexible coating, and thus is beneficial to improving the specific capacity, cycling performance, and safety performance of the high-voltage ternary cathode material.

[0047] In one embodiment, obtaining the flexible coating specifically includes the following steps:

[0048] Obtain aniline;

[0049] Add the polyurethane elastomer to aniline for a dispersion and attachment operation so that aniline adheres to the polyurethane elastomer to obtain a coating solution;

[0050] Perform an in-situ oxidative polymerization operation on the coating solution to obtain the flexible coating.

[0051] It can be understood that since polyaniline is difficult to melt, when using the mechanical blending method, such as mixing and melt-extruding polyaniline and polyurethane elastomer, it is necessary to increase the amount of polyaniline used, and even so, it is difficult to achieve sufficient uniform mixing of polyaniline and polyurethane elastomer, which affects the performance of the coating layer of the ternary cathode active material. Therefore, in this application, aniline is obtained, first making aniline adhere to the polyurethane elastomer, and then performing an in-situ oxidative polymerization operation so that aniline undergoes oxidative polymerization to form a polyaniline film layer on the polyurethane elastomer, which preferably ensures the uniform mixing of the polyurethane elastomer and polyaniline, and preferably ensures that the flexible coating has good flexibility and conductivity, and thus preferably improves the cycling performance and safety performance of the battery.

[0052] In one embodiment, the mass ratio of aniline to the polyurethane elastomer is (0.5 - 1.25):1, which preferably ensures the sufficient coating of the polyurethane elastomer. While preferably ensuring the flexible elasticity of the polyurethane elastomer, it effectively improves the conductivity of the polyurethane elastomer, and further preferably ensures the flexible elasticity and conductivity of the flexible coating.

[0053] In one embodiment, before the step of adding the polyurethane elastomer to aniline for dispersion and attachment operation and after the step of obtaining aniline, the specific steps for obtaining the flexible coating further include: dispersing and mixing aniline with phosphotungstic acid to ensure that during the in-situ oxidative polymerization operation of the coating solution, aniline can effectively combine with protons to undergo in-situ oxidative polymerization to form a polyaniline film on the surface of the polyurethane elastomer, and at the same time preferably ensure the effective doping and embedding of phosphotungstic acid into the polyaniline film, and preferably ensure the structural characteristics of phosphotungstic acid itself, and further preferably ensure the flexible elasticity and conductivity of the flexible coating obtained through the in-situ oxidative polymerization operation.

[0054] In one embodiment, the mass ratio of aniline to phosphotungstic acid is 1:(5 - 10), which preferably ensures the effective progress of in-situ oxidative polymerization, that is, preferably ensures the phosphotungstic acid doping modification of polyurethane, and preferably improves the conductivity of the polyurethane elastomer.

[0055] In one embodiment, H2O2 is used to perform the in-situ oxidative polymerization operation on the coating solution, which preferably realizes the polymerization and oxidation of aniline.

[0056] In one embodiment, the step of using H2O2 to perform the in-situ oxidative polymerization operation on the coating solution is specifically to drop H2O2 into the coating solution and react at room temperature for 20h - 25h.

[0057] In one embodiment, a dispersant is used to perform particle dispersion treatment on the coating solution.

[0058] In one embodiment, the step of performing particle dispersion treatment on the coating solution is specifically: under the condition of a rotation speed of 100RPM, add a dispersant to the coating solution and stir for 30 - 50min, which preferably realizes the sufficient dispersion and uniformity of the coating solution.

[0059] In one embodiment, the dispersant is dodecylbenzenesulfonic acid, and dodecylbenzenesulfonic acid has a good dispersion effect on the coating solution, and further preferably realizes the dispersion uniformity of the coating solution.

[0060] In one embodiment, before obtaining the flexible coating and after the step of in-situ oxidative polymerization operation on the coating solution, the preparation method of the high-voltage ternary cathode material further includes the following steps: drying the coating solution after the in-situ oxidative polymerization operation to reduce the residual moisture or solvent of the high-voltage ternary cathode material, thereby preferably ensuring the electrochemical performance of the high-voltage ternary cathode material.

[0061] In one embodiment, the step of drying the coating solution is specifically as follows: under the condition of 55 °C to 60 °C, vacuum-drying the coating solution after the in-situ oxidative polymerization operation for 20 to 25 h, preferably realizing the reduction of the residual moisture or solvent of the high-voltage ternary cathode material, thereby preferably ensuring the electrochemical performance of the high-voltage ternary cathode material.

[0062] Compared with the prior art, the present invention has at least the following advantages:

[0063] For the high-voltage ternary cathode material of the present invention, the flexible coating body is a mixture of polyaniline and polyurethane elastomer, and is coated on the outer surface of the ternary cathode active material particles, that is, the high-voltage ternary cathode material is multiple ternary cathode active material particles with a mixture of polyaniline and polyurethane elastomer coated on the surface. Since the flexible coating body containing the mixture of polyaniline and polyurethane elastomer has both flexibility and conductivity, during the charge and discharge process of the battery containing the high-voltage ternary cathode material, that is, during the process of lithium deintercalation and insertion, the flexible coating body can adapt to the interface change of the ternary cathode active material particles and maintain the interface stability and dynamic integrity of the ternary cathode active material particles. At the same time, the flexible coating body can provide a uniform lithium-ion transmission interface for the deintercalation and insertion of lithium ions, thereby preferably reducing the problem that the ternary cathode active material particles are easily broken and cause more side reactions, ultimately affecting the cycle performance and safety performance of the battery, and preferably improving the cycle performance and safety performance of the battery.

[0064] The following are some examples. It should be noted that the following examples do not exhaust all possible situations, and the materials used in the following examples can be obtained from commercial channels without special instructions.

[0065] Example 1

[0066] The ternary cathode active material is LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2;

[0067] Preparation of flexible coating: 0.1 kg of aniline monomer was added to 100 L of deionized water and stirred until evenly dispersed. Then, 0.1 kg of polyamide elastomer powder was added and stirred at 100 RPM for 15 min to allow the surface of the polyurethane elastomer powder to fully adsorb the aniline monomer. Subsequently, 0.4 L of an oxidant (3% H2O2 solution) was slowly added dropwise, and the aniline monomer underwent in-situ oxidative polymerization in the polyamide elastomer at room temperature. After the reaction was completed (25 h), it was filtered, washed with deionized water, and vacuum-dried at 60 °C for 24 h to obtain the flexible coating;

[0068] Preparation of high-voltage ternary cathode material: 0.1 kg of the flexible coating was placed in NMP and stirred to obtain a dispersion; 5 kg of the ternary cathode active material was added to the dispersion and stirred, and the solvent was evaporated to obtain the cathode material.

[0069] Example 2

[0070] The ternary cathode active material is LiNi 0.8 Co 0.1 Mn 0.1 O2;

[0071] Preparation of flexible coating: 1 kg of phosphotungstic acid was dissolved in 100 L of deionized water, 0.125 kg of aniline monomer was added and stirred until evenly dispersed, then 0.125 kg of polyamide elastomer powder was added and stirred at 100 RPM for 20 min to allow the surface of the polyurethane elastomer powder to fully adsorb the aniline monomer. Subsequently, 0.4 L of an oxidant (3% H2O2 solution) was slowly added dropwise, and the aniline monomer underwent in-situ oxidative polymerization in the polyamide elastomer at room temperature. After the reaction was completed (about 23 h), it was filtered, washed with deionized water, and vacuum-dried at 55 °C for 25 h to obtain the flexible coating;

[0072] Preparation of high-voltage ternary cathode material: 0.1 kg of the flexible coating was placed in NMP and stirred to obtain a dispersion; 3 kg of the ternary cathode active material was added to the dispersion and stirred, and the solvent was evaporated to obtain the cathode material.

[0073] Example 3

[0074] The ternary cathode active material is LiNi 0.8 Co 0.1 Mn 0.1 O2;

[0075] Preparation of flexible coating: Dissolve 1 kg of phosphotungstic acid in 100 L of deionized water, add 0.2 kg of aniline monomer, stir and disperse evenly, then add 0.4 kg of polyamide elastomer powder, stir at 100 RPM for 20 min to allow the surface of the polyurethane elastomer powder to fully adsorb the aniline monomer, and then slowly drop 0.6 L of oxidant (3% H2O2 solution). At room temperature, in-situ oxidative polymerization reaction of aniline monomer occurs in the polyamide elastomer. After the reaction is completed (25 h), filter, wash with deionized water, and dry in vacuum at 60 °C for 24 h to obtain the flexible coating;

[0076] Preparation of high-voltage ternary cathode material: Place 0.1 kg of flexible coating in NMP and stir to obtain a dispersion; add 2 kg of ternary cathode active material to the dispersion and stir, then evaporate the solvent to obtain the cathode material.

[0077] Example 4

[0078] The ternary cathode active material is LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2;

[0079] Preparation of flexible coating: Dissolve 1 kg of phosphotungstic acid in 100 L of deionized water, add 0.1 kg of aniline monomer, stir and disperse evenly, then add 0.08 kg of polyamide elastomer powder, stir at 100 RPM for 15 min to allow the surface of the polyurethane elastomer powder to fully adsorb the aniline monomer, and then slowly drop 0.4 L of oxidant (3% H2O2 solution). At room temperature, in-situ oxidative polymerization reaction of aniline monomer occurs in the polyamide elastomer. After the reaction is completed (20 h), filter, wash with deionized water, and dry in vacuum at 60 °C for 20 h to obtain the flexible coating;

[0080] Preparation of high-voltage ternary cathode material: Place 0.1 kg of flexible coating in NMP and stir to obtain a dispersion; add 1.25 kg of ternary cathode active material to the dispersion and stir, then evaporate the solvent to obtain the cathode material.

[0081] Comparative Example 1

[0082] The ternary cathode active material is LiNi 0.8 Co 0.1 Mn 0.1 O2;

[0083] The coating is polyaniline;

[0084] The preparation method of high-voltage ternary cathode material is: Place 0.1 kg of polyaniline in NMP and stir to obtain a dispersion; add 2 kg of ternary cathode active material to the dispersion and stir, then evaporate the solvent to obtain the cathode material.

[0085] Comparative Example 2

[0086] The ternary cathode active material is LiNi 0.8 Co 0.1 Mn 0.1 O2;

[0087] The coating is a polyurethane elastomer;

[0088] The preparation method of the high-voltage ternary cathode material is as follows: 0.1 kg of polyurethane elastomer is placed in NMP and stirred to obtain a dispersion; 2 kg of ternary cathode active material is added to the dispersion and stirred, and the solvent is evaporated to obtain the cathode material.

[0089] Comparative Example 3

[0090] The ternary cathode active material is LiNi 0.8 Co 0.1 Mn 0.1 O2;

[0091] The coating is a mixture of polyaniline and polyurethane elastomer, and the mass ratio of polyaniline to polyurethane elastomer is 1:2;

[0092] The preparation method of the coating is as follows: polyamide elastomer powder and polyaniline are melt-blended and granulated;

[0093] The preparation method of the high-voltage ternary cathode material is as follows: 0.1 kg of polyurethane elastomer is placed in NMP and stirred to obtain a dispersion; 2 kg of ternary cathode active material is added to the dispersion and stirred, and the solvent is evaporated to obtain the cathode material.

[0094] Comparative Example 4

[0095] The ternary cathode active material is LiNi 0.8 Co 0.1 Mn 0.1 O2;

[0096] The coating is a mixture of phosphotungstic acid-modified doped polyaniline and polyurethane elastomer (the ratio of phosphotungstic acid to aniline monomer in the phosphotungstic acid-modified doped polyaniline is the same as that in Example 3), and the mixing ratio of phosphotungstic acid-modified doped polyaniline and polyurethane elastomer is calculated based on the mass ratio of aniline monomer: polyurethane = 1:2;

[0097] The preparation method of the coating is as follows: polyamide elastomer powder and phosphotungstic acid-modified doped polyaniline are melt-blended and granulated;

[0098] The preparation method of the high-voltage ternary cathode material is as follows: 0.1 kg of the coating is placed in NMP and stirred to obtain a dispersion; 2 kg of ternary cathode active material is added to the dispersion and stirred, and the solvent is evaporated to obtain the cathode material.

[0099] The positive electrode materials obtained in Examples 1-4 and Comparative Examples 1-4 were fabricated into coin cells for testing the electrochemical performance of lithium-ion batteries. The fabrication steps of the coin cells were as follows: Using N-methylpyrrolidone as a solvent, the positive electrode active material, acetylene black, and PVDF were mixed evenly at a mass ratio of 8:1:1, coated on aluminum foil, dried in a blast dryer at 80 °C for 8 h, and then dried under vacuum at 120 °C for 12 h. The batteries were assembled in an argon-filled glove box. The negative electrode was a lithium metal sheet, the separator was a polypropylene membrane, and the electrolyte was 1 M LiPF6-EC / DMC (1:1, v / v).

[0100] The discharge capacity of the coin cells at a cut-off voltage of 4.45 V and a current rate of 0.1 C, and the capacity retention rate after 50 charge-discharge cycles at a cut-off voltage of 4.45 V and a current rate of 0.1 C at 25 °C were tested. The results are shown in Table 1:

[0101] Table 1: Electrochemical performance of coin cells fabricated from the positive electrode materials obtained in Examples 1-4 and Comparative Examples 1-4

[0102]

[0103] As can be seen from Table 1, the coin cells of Example 1 had higher discharge capacity, discharge specific capacity after cycling, and cycle retention rate compared to the coin cells of Comparative Examples 1-2, indicating that the coated ternary positive electrode active material with the mixed polyaniline and polyurethane elastomer could better improve the discharge capacity and cycle retention rate of the high-voltage ternary positive electrode material. The coin cells of Examples 2-4 had higher discharge capacity and cycle retention rate compared to the coin cells of Comparative Examples 3-4. Please also refer to Figure 2 and Figure 3 , indicating that the surface of the ternary positive electrode active material obtained by in-situ oxidative polymerization in the preparation method of the high-voltage ternary positive electrode material of the present application had good homogeneity of phosphotungstic acid-modified doped polyaniline and polyurethane elastomer, and the coating uniformity of the ternary positive electrode active material was good. In addition, the ternary positive electrode active material obtained by the preparation method of the high-voltage ternary positive electrode material of the present application had good discharge capacity and cycle retention rate.

[0104] The above-described embodiments merely represent several implementation manners of the present invention, and the description thereof is relatively specific and detailed. However, it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A high-voltage ternary cathode material, characterized in that, It includes ternary cathode active material particles and a flexible coating body, and the flexible coating body coats the surface of the ternary cathode active material particles; Among them, the flexible coating body includes a mixture of polyaniline and polyurethane elastomer; The obtaining of the flexible coating body specifically includes the following steps: Obtain aniline; Add the polyurethane elastomer to the aniline for a dispersion and attachment operation so that the aniline attaches to the polyurethane elastomer to obtain a coating solution; Perform an in-situ oxidation polymerization operation on the coating solution to obtain a flexible coating; When the flexible coating covers the surface of the ternary cathode active material, a flexible coating body is formed on the surface of the ternary cathode active material.

2. The high-voltage ternary cathode material according to claim 1, characterized in that, The ternary cathode active material is Li 1+x Ni a Co b Mn c O2, where 1 / 3 ≤ a ≤ 0.8, 0.1 ≤ b ≤ 1 / 3, 0.1 ≤ c ≤ 1 / 3, 0 ≤ x < 0.2, and a + b + c = 1.

3. The high-voltage ternary cathode material according to claim 1, characterized in that, The ternary cathode active material is LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNi 0.4 Co 0.2 Mn 0.4 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2 or LiNi 0.8 Co 0.1 Mn 0.1 O2.

4. The high-voltage ternary cathode material according to claim 1, characterized in that, The polyaniline is phosphotungstic acid-doped modified polyaniline.

5. A preparation method of a high-voltage ternary cathode material, characterized in that, For preparing the high-voltage ternary cathode material according to any one of claims 1 to 4, the preparation method of the high-voltage ternary cathode material includes the following steps: Obtain a flexible coating; Perform a dispersion treatment on the flexible coating; Add the ternary cathode active material to the dispersed flexible coating for a coating operation so that the surface of the ternary cathode active material particles is coated with a flexible coating body to obtain the high-voltage ternary cathode material.

6. The preparation method of the high-voltage ternary cathode material according to claim 5, characterized in that, The obtaining of the flexible coating specifically includes the following steps: Obtain aniline; Add the polyurethane elastomer to the aniline for a dispersion and attachment operation so that the aniline attaches to the polyurethane elastomer to obtain a coating solution; Perform an in-situ oxidation polymerization operation on the coating solution to obtain the flexible coating.

7. The preparation method of the high-voltage ternary cathode material according to claim 6, characterized in that, The mass ratio of the aniline to the polyurethane elastomer is (0.5 - 1.25):

1.

8. The preparation method of the high-voltage ternary cathode material according to claim 6, characterized in that, Before the step of adding the polyurethane elastomer to the aniline for a dispersion and attachment operation and after the step of obtaining the aniline, the obtaining of the flexible coating specifically further includes the following steps: Perform a dispersion and mixing treatment on the aniline and phosphotungstic acid.

9. The preparation method of the high-voltage ternary cathode material according to claim 8, wherein, The mass ratio of the aniline to the phosphotungstic acid is 1:(5 - 10).

10. The preparation method of the high-voltage ternary cathode material according to claim 8, characterized in that, Use H2O2 to perform an in-situ oxidation polymerization operation on the coating solution.

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