Double-coated lithium-rich manganese-based positive electrode material, preparation method and use

Abstract

Disclosed are a double-coated lithium-rich manganese-based positive electrode material, a preparation method and a use. According to the double-coated lithium-rich manganese-based positive electrode material, the surface of a lithium-rich manganese-based positive electrode material is firstly coated with metal oxide to form a first coating layer, the chemical stability of the oxide is relatively good, and a coated sample structure is not prone to being corroded and damaged; and then the first coating layer is coated with one or more of fluoride, oxide and phosphate to form a second coating layer, wherein the fluoride, oxide and phosphate can enter lattices of the lithium-rich manganese-based positive electrode material and occupy oxygen vacancies to inhibit oxygen precipitation.

Description

Double-coated lithium-rich manganese cathode material, preparation method and application Technical Field

[0001] This article relates to the technical field of cathode materials for ion batteries. Specifically, it relates to a double-coated lithium-rich manganese cathode material, a preparation method and an application. Background Art

[0002] Lithium-ion batteries are widely used in electric vehicles, portable electronic products and grid energy storage systems, bringing great convenience to human life. However, with the rapid development of human society, the industry has put forward higher requirements for the energy density of lithium-ion batteries for electric vehicles, consumer (3C) electronic products and energy storage devices. Therefore, the development of high specific capacity and high voltage cathode materials to improve the energy density of batteries has become a research hotspot.

[0003] Currently, several cathode materials have been commercialized in lithium-ion batteries (LIBs), including LiCoO2, LiNi x Co y Mn 1-x-y O2, LiFePO4 and its derivatives. These cathode materials have a capacity lower than 200 mAh / g and are difficult to meet the current market demand of LIBs. The lithium-rich manganese-based material xLi2MnO3·(1-x)LiMO2 (0 < x < 1, M = Ni, Co, Mn and other transition metals and their combinations, hereinafter referred to as LMR) uses inexpensive manganese as the main transition metal element, and the discharge specific capacity can reach more than 250 mAh / g. Therefore, it has attracted extensive attention from researchers.

[0004] Compared with commercial cathode materials LMO, LFP, LCO and NCA, LMR has a higher energy density. With a high discharge specific capacity and energy density, LMR shows very good application prospects. LMR is usually a layered oxide structure, that is, a lithium-rich manganese-based layered oxide (LLOs). Although LLOs have attractive advantages compared with commercially available cathode materials, some existing problems still hinder their industrialization, such as unsatisfactory capacity degradation, voltage decay, slow rate performance, and easy side reactions with electrolytes during subsequent lithium insertion.

[0005] To solve this problem, the prior art modifies the lithium-rich manganese-based cathode material. The modification of the lithium-rich manganese-based cathode material mainly focuses on stabilizing the structure, reducing the corrosion of the electrolyte to the active substance, and improving the migration rate of ions and electrons. The spinel phase can play a protective layer role, inhibit the release of surface lattice oxygen, and provide a three-dimensional (3D) diffusion channel, which is beneficial to Li +The migration of ions. Therefore, in recent years, the formation of spinel phase on the surface of lithium-rich manganese-based cathode materials has attracted extensive attention. However, even with the protection of the spinel phase layer, when pickling is used to remove residual lithium on the surface of the cathode material, the surface of the lithium-rich manganese-based cathode material sample still deteriorates rapidly during cycling.

[0006] In view of this, this article is hereby proposed.

[0007] Summary of the Invention

[0008] The purpose of this article is to provide a double-coated lithium-rich manganese cathode material, a preparation method and an application, so as to improve the stability of the lithium-rich manganese cathode material.

[0009] This article is implemented as follows:

[0010] [[ID=十五]]First, this article provides a double-coated lithium-rich manganese cathode material, including a core and a first coating layer and a second coating layer sequentially coated on the core. The core is a lithium-rich manganese-based cathode material, the first coating layer is an oxide of a first metal, and the second coating layer is at least one of a fluoride of a second metal, an oxide of a second metal, and a phosphate of a second metal.

[0011] In some embodiments, the first metal is at least one of Al, W, Fe, Zr, and Ti.

[0012] In some embodiments, the second metal is at least one of Al, Zr, Sr, and Mg.

[0013] In some embodiments, the mass of the first coating layer is 0.05% to 0.3% of the mass of the core.

[0014] In some embodiments, the mass of the second coating layer is 0.15% to 0.3% of the mass of the core.

[0015] In some embodiments, the average particle size is 2.5 μm to 4 μm.

[0016] [[ID=三十三]]In some embodiments, the core is xLi2MnO3·(1-x)LiMO2, and 0 < x < 1, where M is nickel and manganese.

[0017] In some embodiments, the oxide of the first metal and / or the oxide of the second metal is obtained by sintering the corresponding metal oxide, hydroxide or hydroxyoxide.

[0018] Second, this article provides a preparation method for the double-coated lithium-rich manganese cathode material according to any one of the foregoing embodiments, including:

[0019] The first coating, coating the first coating layer on the surface of the lithium-rich manganese-based cathode material to obtain a single-coated lithium-rich manganese cathode material;

[0020] The second coating is to coat the single-coated lithium-rich manganese positive electrode material with a second coating layer to obtain the double-coated lithium-rich manganese positive electrode material.

[0021] In some embodiments, the first coating step is to mix the lithium-rich manganese-based positive electrode material with the raw material of the first coating layer and perform a second sintering, and the second sintering temperature is 500° C. to 800° C. and the time is 5 h to 8 h.

[0022] In some embodiments, the second coating step is to mix the single-coated lithium-rich manganese positive electrode material with the raw material of the second coating layer and perform a third sintering, and the temperature of the third sintering is 350° C. to 650° C. and the time is 5 h to 8 h.

[0023] In some embodiments, before the second coating is performed, the single-coated lithium-manganese-rich positive electrode material is first acid-washed with a washing solution.

[0024] In some embodiments, the wash solution is an aqueous solution of a weak acid.

[0025] In some embodiments, the concentration of the weak acid in the aqueous solution of the weak acid is 0.01 mol / L to 1 mol / L.

[0026] In some embodiments, the weak acid is at least one of citric acid, phosphoric acid, hypochlorous acid, acetic acid, and formic acid.

[0027] In some embodiments, in the pickling step, the liquid-to-solid ratio of the single-coated lithium-rich manganese positive electrode material to the washing solution is (10:1 to 1:1) ml / g.

[0028] In some embodiments, in the pickling step, the single-coated lithium manganese-rich positive electrode material is mixed with the washing solution and stirred for 10 minutes to 120 minutes, and then the single-coated lithium manganese-rich positive electrode material is separated and the residual washing solution on the surface is washed with deionized water, and then dried and coated for the second time.

[0029] In some embodiments, the drying step is performed at a temperature of 60° C. to 100° C. and for a time of 8 to 12 hours.

[0030] In some embodiments, the method further includes preparing a lithium-rich manganese-based positive electrode material: mixing a precursor corresponding to the lithium-rich manganese-based positive electrode material with a lithium salt and then sintering the mixture for the first time to obtain the lithium-rich manganese-based positive electrode material.

[0031] In some embodiments, in the step of preparing the lithium-rich manganese-based positive electrode material, the ratio of the molar amount of lithium element to the total molar amount of nickel and manganese elements in the precursor is (1.1-1.65):1.

[0032] In some embodiments, the temperature of the first sintering step is 750° C. to 950° C., and the time is 8 hours to 15 hours.

[0033] In some embodiments, the precursor is Ni 1-x Mn x (OH)2, where x = 0.4 to 0.8.

[0034] In a third aspect, this article provides an electrode comprising the double-coated lithium-manganese-rich positive electrode material described in any one of the aforementioned embodiments.

[0035] In a fourth aspect, this document provides a battery comprising the electrode described in the aforementioned embodiment.

[0036] In a fifth aspect, this document provides an electrical device comprising the battery described in the aforementioned embodiment.

[0037] This article has the following beneficial effects:

[0038] The double-coated lithium-rich manganese positive electrode material provided in this article is first coated with a metal oxide on the surface of the lithium-rich manganese-based positive electrode material to form a first coating layer, wherein the oxide has relatively good chemical stability and the coated sample structure is not easily corroded and destroyed; then one or more of fluoride, oxide and phosphate are coated on the first coating layer to form a second coating layer, wherein the fluoride, oxide and phosphate can enter the lattice of the lithium-rich manganese positive electrode material, occupy oxygen vacancies and inhibit oxygen precipitation. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of this invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of this invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0040] FIG1 is a flow chart of an embodiment of the present invention;

[0041] FIG2 is a flow chart of Example 1;

[0042] FIG3 is a SEM image of the product obtained in Example 1;

[0043] FIG4 is a SEM image of the product obtained in Comparative Example 1;

[0044] Figure 5 is a SEM image of the product obtained in Comparative Example 2;

[0045] FIG6 is a SEM image of the product obtained in Comparative Example 3. DETAILED DESCRIPTION

[0046] To make the purpose, technical solutions and advantages of the embodiments herein clearer, the technical solutions in the embodiments herein are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer were followed. Where the manufacturer of the reagents or instruments used is not specified, all are commercially available conventional products.

[0047] In the first aspect, this article provides a double-coated lithium-rich manganese positive electrode material, including a core and a first coating layer and a second coating layer sequentially coated on the core, wherein the core is a lithium-rich manganese-based positive electrode material, the first coating layer is an oxide of a first metal, and the second coating layer is at least one of a fluoride of a second metal, an oxide of a second metal, and a phosphate of a second metal.

[0048] The double-coated lithium-rich manganese positive electrode material provided in this article first coats the surface of the lithium-rich manganese-based positive electrode material with a metal oxide, wherein the oxide has relatively good chemical stability and the coated sample structure is not easily corroded and destroyed; then one or more of fluoride, oxide and phosphate are coated on the first coating layer to form a second coating layer, wherein the fluoride, oxide and phosphate can enter the lattice of the lithium-rich manganese positive electrode material, occupy oxygen vacancies and inhibit oxygen precipitation.

[0049] In some embodiments, the first coating layer can be one of the oxide, hydroxide and oxyhydroxide of the first metal, or a combination of two or three, for example, a combination of the oxide and hydroxide of the first metal; the second coating layer can be one of the fluoride, oxide and phosphate of the second metal, or a combination of two or three, for example, a combination of the fluoride and oxide of the second metal.

[0050] In some embodiments, the first metal is at least one of Al, W, Fe, Zr and Ti. In some cases, the first metal can be one of Al, W, Fe, Zr and Ti, or a combination of two or more, for example, a combination of aluminum and iron.

[0051] In some embodiments, the second metal is at least one of Al, Zr, Sr and Mg. In some cases, the second metal can be one of Al, Zr, Sr and Mg, or a combination of two or more, for example, a combination of Zr and Sr.

[0052] Specifically, the second coating layer may be at least one of aluminum oxide, cerium oxide, zirconium oxide, magnesium oxide, aluminum fluoride, cerium fluoride, zirconium fluoride, magnesium fluoride, aluminum phosphate, cerium phosphate, zirconium phosphate, and magnesium phosphate.

[0053] In some embodiments, the mass of the first coating layer is 0.05% to 0.3% of the mass of the core, specifically, it can be 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3% or any value between 0.05% and 0.3%.

[0054] In some embodiments, the mass of the second coating layer is 0.15% to 0.3% of the mass of the core, specifically, it can be 0.15%, 0.2%, 0.25%, 0.3% or any value between 0.15% and 0.3%.

[0055] The presence of the first coating layer and the second coating layer can improve the stability of the core material, but too thick coating layer will also increase the difficulty of lithium ion migration and reduce the capacity. Therefore, the coating agent needs to be added appropriately.

[0056] In some embodiments, the average particle size is 2.5 μm - 4 μm.

[0057] In some embodiments, the core is xLi2MnO3·(1 - x)LiMO2, where 0 < x < 1 and M is nickel and manganese.

[0058] In some embodiments, the oxide of the first metal and / or the oxide of the second metal are sintered from the corresponding metal oxides, hydroxides or oxyhydroxides.

[0059] In a second aspect, the present disclosure provides a method for preparing the double-coated lithium-rich manganese cathode material according to any one of the foregoing embodiments. As shown in Figure 1, the method includes:

[0060] The first coating step: coating a first coating layer on the surface of the lithium-rich manganese-based cathode material to obtain a single-coated lithium-rich manganese cathode material;

[0061] The second coating step: coating a second coating layer on the single-coated lithium-rich manganese cathode material to obtain the double-coated lithium-rich manganese cathode material. <m

[0062] The method for preparing the double-coated lithium-rich manganese cathode material in the present disclosure is simple and easy to implement, has low manufacturing cost, good reproducibility, and is convenient for large-scale industrial production.

[0063] In some embodiments, in the first coating step, the lithium-rich manganese-based cathode material and the raw materials of the first coating layer are mixed and then sintered for the second time. The temperature of the second sintering is 500°C to 800°C, and the time is 5 h to 8 h.

[0064] In some embodiments, when coating the first coating layer, the lithium-rich manganese-based cathode material and the raw materials of the first coating layer are first fully mixed. The specific mixing method can be ball milling, stirring, etc., to ensure the uniformity of mixing as much as possible.

[0065] Among them, the raw material of the first coating layer can be selected from one or more of the oxide, hydroxide and oxyhydroxide of the first metal according to the target product. Specifically, the raw material of the first coating layer can be at least one of iron oxide, aluminum oxide, tungsten oxide, zirconium oxide, titanium oxide, aluminum hydroxide, tungsten hydroxide, iron hydroxide, zirconium hydroxide, titanium hydroxide, oxyhydroxide aluminum, oxyhydroxide zirconium and oxyhydroxide titanium.

[0066] Generally, in order to ensure coating uniformity, the raw material of the first coating layer can be selected as nano-scale powder.

[0067] In addition, in some embodiments, in order to increase the bonding strength between the first coating layer and the lithium-rich manganese-based positive electrode material, the second sintering is usually carried out at a relatively high temperature. However, too high a temperature may cause the structure of the lithium-rich manganese-based positive electrode material to be destroyed, thereby reducing the stability of the positive electrode material. Therefore, the temperature of the second sintering step should not be too high. Specifically, in some embodiments, the temperature of the second sintering can be 500°C, 600°C, 700°C, 800°C or any value between 500°C and 800°C. Similarly, a sintering time that is too long may also cause the collapse of the structure and affect the stability of the material. Therefore, a time of 5h to 8h is more appropriate, specifically 5h, 6h, 7h, 8h or any value between 5h and 8h.

[0068] In some embodiments, the second coating step is to mix the single-coated lithium-rich manganese positive electrode material with the raw material of the second coating layer and perform a third sintering, and the temperature of the third sintering is 350° C. to 650° C. and the time is 5 h to 8 h.

[0069] In some embodiments, when coating the second coating layer, the single-coated lithium manganese-rich positive electrode material and the raw material of the second coating layer are first fully mixed. The specific mixing method can be ball milling mixing, stirring mixing, etc., to ensure the uniformity of mixing as much as possible.

[0070] The raw material of the second coating layer can be selected from one or more of the fluoride, oxide and phosphate of the second metal according to the target product. Usually, in order to ensure the uniformity of the coating, the raw material of the second coating layer can be selected from nano-scale powder.

[0071] In addition, in some embodiments, in order to maintain the stability of the capacity and structure, the temperature should not be too high during the third sintering, but too low a temperature will cause the bonding force between the two coating layers to decrease, thereby affecting the strength of the material. Therefore, the temperature cannot be too low during the third sintering. Specifically, in some embodiments, the temperature of the third sintering can be 350°C, 450°C, 550°C, 650°C or any value between 350°C and 650°C. Similarly, a sintering time that is too long may also cause the collapse of the structure and affect the stability of the material. Therefore, a time of 5h to 8h is more appropriate, specifically 5h, 6h, 7h, 8h or any value between 5h and 8h.

[0072] In some embodiments, before the second coating is performed, the single-coated lithium-manganese-rich positive electrode material is first acid-washed with a washing solution.

[0073] Acid pickling is used to remove residual alkali on the surface of the material. After the lithium-rich manganese positive electrode material is directly pickled, the surface of the material will deteriorate rapidly during the cycle, thereby reducing the stability of the material. If the material is pickled after the second coating, the residual lithium may not be washed out due to the obstruction of the two coating layers, thereby affecting the performance of the material. Therefore, some embodiments pickle the single-coated lithium-rich manganese positive electrode material before the second coating. At this time, the surface of the lithium-rich manganese positive electrode material is coated with the first coating layer. The thickness of the first coating layer is not too large, so that the first coating layer can play a certain barrier role without completely blocking the role of the washing solution and the residual lithium. It can effectively remove residual lithium while reducing the damage of the washing solution to the surface of the lithium-rich manganese positive electrode material. In some embodiments, the washing solution is an aqueous solution of a weak acid. Strong acid will destroy the structure of the first coating layer and the core, thereby reducing the stability of the material.

[0074] In some embodiments, the concentration of the weak acid in the aqueous solution is 0.01 mol / L to 1 mol / L. If the concentration is too high, the structure of the first coating layer and the core may be destroyed, reducing the stability of the material. Therefore, even if a weak acid is used to remove residual lithium on the surface of the material, the concentration of the weak acid in the wash solution is not easy to be too high. Specifically, in some embodiments, the concentration of the weak acid can be 0.01 mol / L, 0.1 mol / L, 0.5 mol / L, 1 mol / L, or any value between 0.01 mol / L and 1 mol / L.

[0075] In some embodiments, the weak acid is at least one of citric acid, phosphoric acid, hypochlorous acid, acetic acid and formic acid, specifically, it can be one of citric acid, phosphoric acid, hypochlorous acid, acetic acid and formic acid, or it can be a combination of two or more, for example, it can be a combination of citric acid and phosphoric acid.

[0076] In some embodiments, in the pickling step, the liquid-to-solid ratio of the single-coated lithium-rich manganese positive electrode material to the washing solution is (10:1 to 1:1) ml / g, specifically, it can be 10:1 ml / g, 5:1 ml / g, 2:1 ml / g, 1:1 ml / g or any value between (10:1 to 1:1) ml / g.

[0077] If the liquid-solid ratio is too high, on the one hand, washing liquid will be wasted, which is not conducive to cost savings, and on the other hand, it will be not conducive to the subsequent separation of materials; however, if the liquid-solid ratio is too low, on the one hand, it will affect the effect and efficiency of residual lithium removal, and on the other hand, when the solid phase moves in the liquid phase, repeated friction between solid particles may cause part of the coating layer to fall off, affecting the material performance.

[0078] In some embodiments, in the pickling step, the single-coated lithium manganese-rich positive electrode material is mixed with the washing solution and stirred for 10 minutes to 120 minutes, and then the single-coated lithium manganese-rich positive electrode material is separated and the residual washing solution on the surface is washed with deionized water, and then dried and coated for the second time.

[0079] In some embodiments, the temperature of the drying step is 60°C to 100°C, and the time is 8h to 12h. The purpose is to remove moisture, so the temperature of this step should not be too high. Specifically, the temperature of the drying step can be 60°C, 70°C, 80°C, 90°C, 100°C or any value between 60°C and 100°C; the time of the drying step can be 8h, 9h, 10h, 11h, 12h or any value between 8h and 12h.

[0080] In some embodiments, the method further includes preparing a lithium-rich manganese-based positive electrode material: mixing a precursor corresponding to the lithium-rich manganese-based positive electrode material with a lithium salt and then sintering the mixture for the first time to obtain the lithium-rich manganese-based positive electrode material.

[0081] In some embodiments, in the preparation step of the lithium-rich manganese-based positive electrode material, the ratio of the molar amount of lithium element to the total molar amount of nickel and manganese elements in the precursor is (1.1 to 1.65):1, specifically, it can be 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.65:1 or any value between 1.1:1 and 1.65:1.

[0082] In some embodiments, the temperature of the first sintering step is 750°C to 950°C, and the time is 8h to 15h to form a lithium-rich manganese-based layered oxide. Specifically, the temperature can be 750°C, 800°C, 850°C, 900°C, 950°C or any value between 750°C and 950°C; the time can be 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h or any value between 8h and 15h.

[0083] In some embodiments, the precursor is Ni1-x Mn x (OH)2, where x = 0.4 to 0.8.

[0084] In a third aspect, this article provides an electrode comprising the double-coated lithium-manganese-rich positive electrode material described in any one of the aforementioned embodiments.

[0085] In a fourth aspect, this document provides a battery comprising the electrode described in the aforementioned embodiment.

[0086] In a fifth aspect, this document provides an electrical device comprising the battery described in the aforementioned embodiment.

[0087] The features and performance of this invention are further described in detail below in conjunction with the embodiments.

[0088] Example 1

[0089] This embodiment provides a method for preparing a lithium-rich manganese-based positive electrode material. The process is shown in FIG2 and specifically includes the following steps:

[0090] (1) Preparation of Ni by coprecipitation 0.35 Mn0. 65 (OH)2 precursor;

[0091] (2) Ni obtained in step (1) 0.35 Mn 0.65 The (OH)2 precursor and Li2CO3 powder were mixed evenly according to the molar ratio of lithium element to nickel and manganese element of 1.25, sintered at 900℃ in air atmosphere for 15h, and cooled to room temperature to obtain lithium-rich manganese-based positive electrode material;

[0092] (3) The lithium-rich manganese-based positive electrode material obtained in step (2) is uniformly mixed with aluminum oxide, wherein the amount of aluminum oxide is 0.2 wt % of the lithium-rich manganese-based positive electrode material, and the uniformly mixed sample is sintered at 550° C. in an air atmosphere for 5 h, and after cooling to room temperature, an oxide-coated lithium-rich manganese-based positive electrode material is obtained;

[0093] (4) Add the oxide-coated lithium-rich manganese-based positive electrode material obtained in step (3) and 0.01 mol / L citric acid solution at a liquid-to-solid ratio of 5:1 into a stirrer and stir for 30 minutes. Wash the residual acid with deionized water until the pH is 7, filter, and then dry in an oven at 80°C for 12 hours.

[0094] (5) The dried product obtained in step (4) is mixed evenly with AlF3 nanopowder, wherein the amount of AlF3 is 0.15wt% of the lithium-rich manganese-based positive electrode material, and then placed in an air atmosphere and sintered at 500°C for 5h. After cooling to room temperature, the final product shown in Figure 3 can be obtained.

[0095] Example 2:

[0096] This embodiment provides a method for preparing a lithium-rich manganese-based positive electrode material, comprising the following specific steps:

[0097] (1) Preparation of Ni by coprecipitation 0.37 Mn 0.63 (OH)2 precursor;

[0098] (2) Ni obtained in step (1) 0.37 Mn 0.63 The (OH)2 precursor and Li2CO3 powder were mixed evenly according to the molar ratio of lithium element to nickel and manganese element of 1.2, sintered at 850℃ in air atmosphere for 15h, and cooled to room temperature to obtain a sintered product;

[0099] (3) The calcined product obtained in step (2) is mixed evenly with tungsten oxide, wherein the amount of tungsten oxide is 0.15 wt % of the lithium-rich manganese-based positive electrode material, and the mixed sample is sintered at 600 ° C. in an air atmosphere for 5 h, and after cooling to room temperature, an oxide-coated lithium-rich manganese-based positive electrode material is obtained;

[0100] (4) adding the tungsten oxide-coated lithium-rich manganese-based positive electrode material obtained in step (3) and 0.01 mol / L acetic acid solution at a liquid-solid ratio of 5:1 into a stirrer and stirring for 30 minutes, washing the residual acid with deionized water until the pH is 7, filtering, and then drying in an oven at 80°C for 12 hours;

[0101] (5) The dried product obtained in step (4) is mixed evenly with 0.15% ZrF3 nanopowder, wherein the amount of ZrF3 is 0.15wt% of the lithium-rich manganese-based positive electrode material, and then placed in an air atmosphere and sintered at 500°C for 5h. After cooling to room temperature, the final product can be obtained.

[0102] Example 3:

[0103] This embodiment provides a method for preparing a lithium-rich manganese-based positive electrode material, comprising the following specific steps:

[0104] (1) Preparation of NiO by coprecipitation method. 40 Mn0. 60 (OH)2 precursor;

[0105] (2) Ni obtained in step (1) 0.40 Mn 0.60 (OH)2 precursor and Li2CO3 powder were mixed evenly according to the molar ratio of lithium element to nickel and manganese element of 1.1, sintered at 900℃ in air atmosphere for 15h, and cooled to room temperature to obtain a sintered product;

[0106] (3) uniformly mixing the calcined product obtained in step (2) with zirconium oxide, wherein the amount of zirconium oxide used is 0.2 wt % of the lithium-rich manganese-based positive electrode material; sintering the uniformly mixed sample at 550° C. in an air atmosphere for 5 h, and cooling to room temperature to obtain an oxide-coated lithium-rich manganese-based positive electrode material;

[0107] (4) Add the oxide-coated lithium-rich manganese-based positive electrode material obtained in step (3) and 0.01 mol / L phosphoric acid solution at a liquid-solid ratio of 5:1 into a stirrer and stir for 30 minutes. Wash the residual acid with deionized water until the pH is 7, filter, and then dry in an oven at 80°C for 12 hours.

[0108] (5) The dried product obtained in step (4) is mixed evenly with nano-powder of magnesium fluoride, wherein the amount of magnesium fluoride is 0.15 wt% of the lithium-rich manganese-based positive electrode material, and then placed in an air atmosphere at 500 ° C. for 5 hours. After cooling to room temperature, the final product can be obtained.

[0109] Example 4:

[0110] This embodiment provides a method for preparing a lithium-rich manganese-based positive electrode material, comprising the following specific steps:

[0111] (1) Preparation of Ni by coprecipitation 0.37 Mn 0.63 (OH)2 precursor;

[0112] (2) Ni0. 37 Mn0. 63 The (OH)2 precursor and Li2CO3 powder were mixed evenly according to the molar ratio of lithium element to nickel and manganese element of 1.2, sintered at 850℃ in air atmosphere for 15h, and cooled to room temperature to obtain a sintered product;

[0113] (3) The calcined product obtained in step (2) is uniformly mixed with iron oxide, wherein the amount of iron oxide is 0.3 wt % of the lithium-rich manganese-based positive electrode material, and the uniformly mixed sample is sintered at 550° C. in an air atmosphere for 5 h, and after cooling to room temperature, an iron oxide-coated lithium-rich manganese-based positive electrode material is obtained;

[0114] (4) Add the iron oxide-coated lithium-rich manganese-based positive electrode material obtained in step (3) and 0.01 mol / L formic acid solution at a liquid-solid ratio of 5:1 into a stirrer and stir for 30 minutes. Wash the residual acid with deionized water until the pH is 7, filter, and then dry in an oven at 80°C for 12 hours.

[0115] (5) The dried product obtained in step (4) is mixed evenly with nano-powder of aluminum phosphate, wherein the amount of aluminum phosphate is 0.2 wt% of the lithium-rich manganese-based positive electrode material, and then placed in an air atmosphere and sintered at 500 ° C for 5 h. After cooling to room temperature, the final product can be obtained.

[0116] Example 5:

[0117] This embodiment provides a method for preparing a lithium-rich manganese-based positive electrode material, comprising the following specific steps:

[0118] (1) Preparation of Ni by coprecipitation 0.37 Mn0. 63 (OH)2 precursor;

[0119] (2) Ni obtained in step (1) 0.37 Mn 0.63 The (OH)2 precursor and Li2CO3 powder were mixed evenly according to the molar ratio of lithium element to nickel and manganese element of 1.2, sintered at 850℃ in air atmosphere for 15h, and cooled to room temperature to obtain a sintered product;

[0120] (3) The calcined product obtained in step (2) is mixed evenly with tungsten hydroxide, wherein the amount of tungsten hydroxide is 0.3 wt % of the lithium-rich manganese-based positive electrode material, and the mixed sample is sintered at 550° C. in an air atmosphere for 5 h, and after cooling to room temperature, a tungsten oxide-coated lithium-rich manganese-based positive electrode material is obtained;

[0121] (4) adding the tungsten oxide-coated lithium-rich manganese-based positive electrode material obtained in step (3) and 0.01 mol / L hypochlorous acid solution at a liquid-solid ratio of 5:1 into a stirrer and stirring for 30 minutes, washing the residual acid with deionized water until the pH is 7, filtering, and then drying in an oven at 80°C for 12 hours;

[0122] (5) The dried product obtained in step (4) is mixed evenly with nano-powder of zirconium oxide, wherein the amount of zirconium oxide is 0.2 wt% of the lithium-rich manganese-based positive electrode material, and then placed in an air atmosphere and sintered at 500 ° C for 5 h. After cooling to room temperature, the final product can be obtained.

[0123] Example 6:

[0124] This embodiment provides a method for preparing a lithium-rich manganese-based positive electrode material, comprising the following specific steps:

[0125] (1) Preparation of Ni by coprecipitation 0.35 Mn 0.65 (OH)2 precursor;

[0126] (2) Ni obtained in step (1) 0.35Mn 0.65 The (OH)2 precursor and Li2CO3 powder were mixed evenly according to the molar ratio of lithium element to nickel and manganese element of 1.25, sintered at 900℃ in air atmosphere for 15h, and cooled to room temperature to obtain a sintered product;

[0127] (3) The calcined product obtained in step (2) is uniformly mixed with iron oxyhydroxide, wherein the amount of iron oxyhydroxide is 0.2 wt % of the lithium-rich manganese-based positive electrode material, and the uniformly mixed sample is sintered at 600° C. in an air atmosphere for 5 h, and after cooling to room temperature, an iron oxide-coated lithium-rich manganese-based positive electrode material is obtained;

[0128] (4) Add the iron oxide-coated lithium-rich manganese-based positive electrode material obtained in step (3) and 0.01 mol / L acetic acid solution at a liquid-solid ratio of 5:1 into a stirrer and stir for 30 minutes. Wash the residual acid with deionized water until the pH is 7, filter, and then dry in an oven at 80°C for 12 hours.

[0129] (5) The dried product obtained in step (4) is mixed evenly with nano-powder of magnesium oxide, wherein the amount of magnesium oxide is 0.15 wt% of the lithium-rich manganese-based positive electrode material, and then placed in an air atmosphere and sintered at 550 ° C for 5 h. After cooling to room temperature, the final product can be obtained.

[0130] Example 7:

[0131] This embodiment provides a method for preparing a lithium-rich manganese-based positive electrode material, comprising the following specific steps:

[0132] (1) Preparation of Ni by coprecipitation 0.35 Mn0. 65 (OH)2 precursor;

[0133] (2) Ni obtained in step (1) 0.35 Mn0. 65 The (OH)2 precursor and Li2CO3 powder were mixed evenly according to the molar ratio of lithium element to nickel and manganese element of 1.25, sintered at 900℃ in air atmosphere for 15h, and cooled to room temperature to obtain a sintered product;

[0134] (3) The calcined product obtained in step (2) is mixed evenly with aluminum hydroxide, wherein the amount of aluminum hydroxide is 0.3 wt % of the lithium-rich manganese-based positive electrode material, and the mixed sample is sintered at 550° C. in an air atmosphere for 5 h, and after cooling to room temperature, an alumina-coated lithium-rich manganese-based positive electrode material is obtained;

[0135] (4) Add the alumina-coated lithium-rich manganese-based positive electrode material obtained in step (3) and 0.01 mol / L formic acid solution at a liquid-solid ratio of 5:1 into a stirrer and stir for 30 minutes. Wash the residual acid with deionized water until the pH is 7, filter, and then dry in an oven at 80°C for 12 hours.

[0136] (5) The dried product obtained in step (4) is mixed evenly with nano-powder of strontium phosphate, wherein the amount of strontium phosphate is 0.15wt% of the lithium-rich manganese-based positive electrode material, and then placed in an air atmosphere at 500°C for 5h. After cooling to room temperature, the final product can be obtained.

[0137] Example 8:

[0138] This embodiment provides a method for preparing a lithium-rich manganese-based positive electrode material, comprising the following specific steps:

[0139] (1) Preparation of Ni by coprecipitation 0.40 Mn 0.60 (OH)2 precursor;

[0140] (2) Ni obtained in step (1) 0.40 Mn 0.60 (OH)2 precursor and Li2CO3 powder were mixed evenly according to the molar ratio of lithium element to nickel and manganese element of 1.1, sintered at 900℃ in air atmosphere for 15h, and cooled to room temperature to obtain a sintered product;

[0141] (3) uniformly mixing the calcined product obtained in step (2) with zirconium hydroxide, wherein the amount of zirconium hydroxide used is 0.2 wt % of the lithium-rich manganese-based positive electrode material; sintering the uniformly mixed sample at 550° C. in an air atmosphere for 5 h, and cooling to room temperature to obtain a zirconium oxide-coated lithium-rich manganese-based positive electrode material;

[0142] (4) adding the zirconium oxide-coated lithium-rich manganese-based positive electrode material obtained in step (3) and 0.01 mol / L citric acid solution into a stirrer, mixing and stirring for 30 minutes at a liquid-to-solid ratio of 5:1, washing the residual acid with deionized water until the pH reaches 7, filtering, and then drying in an oven at 80°C for 12 hours;

[0143] (5) The dried product obtained in step (4) is mixed evenly with nano-powder of strontium oxide, wherein the amount of strontium oxide is 0.2 wt% of the lithium-rich manganese-based positive electrode material, and then placed in an air atmosphere at 450 ° C. for 5 hours. After cooling to room temperature, the final product can be obtained.

[0144] Example 9:

[0145] This embodiment provides a method for preparing a lithium-rich manganese-based positive electrode material, comprising the following specific steps:

[0146] (1) Preparation of Ni by coprecipitation 0.40 Mn 0.60 (OH)2 precursor;

[0147] (2) Ni obtained in step (1) 0.40 Mn 0.60 (OH)2 precursor and Li2CO3 powder were mixed evenly according to the molar ratio of lithium element to nickel and manganese element of 1.1, sintered at 900℃ in air atmosphere for 15h, and cooled to room temperature to obtain a sintered product;

[0148] (3) The calcined product obtained in step (2) is mixed evenly with aluminum oxide hydroxide, wherein the amount of aluminum oxide hydroxide is 0.3 wt % of the lithium-rich manganese-based positive electrode material, and the mixed sample is sintered at 550° C. in an air atmosphere for 5 h, and after cooling to room temperature, an aluminum oxide-coated lithium-rich manganese-based positive electrode material is obtained;

[0149] (4) Add the alumina-coated lithium-rich manganese-based positive electrode material obtained in step (3) and 0.01 mol / L acetic acid solution at a liquid-solid ratio of 5:1 into a stirrer and stir for 30 minutes. Wash the residual acid with deionized water until the pH is 7, filter, and then dry in an oven at 80°C for 12 hours.

[0150] (5) The dried product obtained in step (4) is mixed evenly with nano-powder of zirconium phosphate, wherein the amount of zirconium phosphate is 0.2 wt% of the lithium-rich manganese-based positive electrode material, and then placed in an air atmosphere and sintered at 500 ° C for 5 h. After cooling to room temperature, the final product can be obtained.

[0151] Example 10:

[0152] A method for preparing a lithium-rich manganese-based positive electrode material comprises the following specific steps:

[0153] (1) Preparation of Ni by coprecipitation 0.35 Mn0. 65 (OH)2 precursor;

[0154] (2) Ni obtained in step (1) 0.35 Mn 0.65 The (OH)2 precursor and Li2CO3 powder were mixed evenly according to the molar ratio of lithium element to nickel and manganese element of 1.65, sintered at 750℃ in air atmosphere for 8h, and cooled to room temperature to obtain a sintered product;

[0155] (3) The calcined product obtained in step (2) is mixed evenly with alumina, wherein the amount of alumina is 0.05 wt % of the lithium-rich manganese-based positive electrode material, and the mixed sample is sintered at 800° C. in an air atmosphere for 8 h, and after cooling to room temperature, an oxide-coated lithium-rich manganese-based positive electrode material is obtained;

[0156] (4) Add a certain amount of the oxide-coated lithium-rich manganese-based positive electrode material obtained in step (3) and 0.1 mol / L citric acid solution in a blender at a liquid-to-solid ratio of 10:1, and stir for 30 minutes. Wash the residual acid with deionized water until the pH is 7, filter, and then dry in an oven at 80°C for 12 hours.

[0157] (5) The dried product obtained in step (4) is mixed evenly with AlF3 nanopowder, wherein the amount of AlF3 is 0.15wt% of the lithium-rich manganese-based positive electrode material, and then placed in an air atmosphere and sintered at 350°C for 8h. After cooling to room temperature, the final product can be obtained.

[0158] Example 11:

[0159] The only difference from Example 1 is that, in step (3), the calcined product obtained in step (2) is mixed evenly with aluminum oxide and ferric oxyhydroxide, wherein the amount of aluminum oxide and ferric oxyhydroxide is 0.1% of the calcined product, and the mixed sample is sintered at 550° C. in an air atmosphere for 5 h. After cooling to room temperature, an oxide-coated lithium-rich manganese-based positive electrode material is obtained.

[0160] Example 12:

[0161] The only difference from Example 1 is that step (5): the dried product obtained in step (4) is mixed with AlF 3、 ZF 3、 The nano powders of aluminum phosphate are mixed evenly, wherein AlF 3、 ZF 3、 The amount of aluminum phosphate used is 0.05% of the dried product, which is then sintered at 500° C. in an air atmosphere for 5 hours and cooled to room temperature to obtain the final product.

[0162] Comparative Example 1:

[0163] This embodiment provides a method for preparing a lithium-rich manganese-based positive electrode material, comprising the following specific steps:

[0164] (1) Preparation of Ni by coprecipitation 0.35 Mn 0.65 (OH)2 precursor;

[0165] (2) Ni obtained in step (1) 0.35 Mn 0.65After the (OH)2 precursor and Li2CO3 powder are evenly mixed, the mixed sample is sintered at 900°C in an air atmosphere for 15 hours, wherein the molar ratio of lithium element to nickel and manganese element is 1.25, and a sintered product is obtained after cooling to room temperature;

[0166] (3) The calcined product obtained in step (2) is mixed evenly with alumina, wherein the amount of alumina is 0.3 wt % of the lithium-rich manganese-based positive electrode material. The mixed sample is sintered in an air atmosphere and cooled to room temperature to obtain an oxide-coated lithium-rich manganese-based positive electrode material, the structure of which is shown in FIG4 .

[0167] That is, the difference from Example 1 is that there is no pickling process.

[0168] Comparative Example 2:

[0169] This embodiment provides a method for preparing a lithium-rich manganese-based positive electrode material, comprising the following specific steps:

[0170] (1) Preparation of Ni by coprecipitation 0.35 Mn 0.65 (OH)2 precursor;

[0171] (2) Ni obtained in step (1) 0.35 Mn 0.65 After the (OH)2 precursor and Li2CO3 powder are evenly mixed, the mixed sample is sintered at 900°C in an air atmosphere for 15 hours, wherein the molar ratio of lithium element to nickel and manganese element is 1.25, and a sintered product is obtained after cooling to room temperature;

[0172] (3) Add a certain amount of the product obtained in step (2) and 0.01M citric acid solution in a blender at a liquid-to-solid ratio of 5:1, mix and stir for 30 minutes, wash the residual acid with deionized water until the pH reaches 7, filter, and then dry in an oven at 80°C for 12 hours;

[0173] (4) The dried product obtained in step (3) is mixed evenly with AlF3 nanopowder, wherein the amount of AlF3 is 0.15wt% of the lithium-rich manganese-based positive electrode material, and then placed in an air atmosphere and sintered at 450°C for 5h. After cooling to room temperature, the final product is obtained, and the structure is shown in Figure 5.

[0174] That is, the difference from Example 1 is that the alumina coating process is not added.

[0175] Comparative Example 3:

[0176] This embodiment provides a method for preparing a lithium-rich manganese-based positive electrode material, comprising the following specific steps:

[0177] (1) Preparation of Ni by coprecipitation0.35 Mn 0.65 (OH)2 precursor;

[0178] (2) Ni obtained in step (1) 0.35 Mn 0.65 After the (OH)2 precursor and Li2CO3 powder are evenly mixed, the mixed sample is sintered at 900°C in an air atmosphere for 15 hours, wherein the molar ratio of lithium element to nickel and manganese element is 1.25, and a sintered product is obtained after cooling to room temperature;

[0179] (3) uniformly mixing the calcined product obtained in step (2) with an oxide, wherein the amount of the oxide is 0.3 wt % of the lithium-rich manganese-based positive electrode material, and then sintering the uniformly mixed sample in an air atmosphere, and after cooling to room temperature, an aluminum oxide-coated lithium-rich manganese-based positive electrode material can be obtained;

[0180] (4) Add the alumina-coated lithium-rich manganese-based positive electrode material obtained in step (3) and 0.01M sulfuric acid solution at a liquid-to-solid ratio of 5:1 into a blender and stir for 30 minutes. Wash the residual acid with deionized water until the pH is 7, filter, and then dry in an oven at 80°C for 12 hours.

[0181] (5) The dried product obtained in step (4) is mixed evenly with AlF3 nanopowder, wherein the amount of AlF3 is 0.15wt% of the lithium-rich manganese-based positive electrode material, and then placed in an air atmosphere and sintered at 450°C for 5h. After cooling to room temperature, the final product is obtained, and the structure is shown in Figure 6.

[0182] That is, the difference from Example 1 is that sulfuric acid pickling replaces the citric acid pickling process.

[0183] Comparative Example 4:

[0184] The only difference from Example 5 is that the calcined product is pickled and then coated with tungsten hydroxide and zirconium oxide (the coating with alumina is not pickled).

[0185] Comparative Example 5:

[0186] The only difference from Example 5 is that the di-sintered product is pickled to obtain the final product (no pickling is performed after coating tungsten oxide).

[0187] Comparative Example 6:

[0188] The only difference from Example 5 is that in step (4), the concentration of the hypochlorous acid solution is 2 mol / L.

[0189] Comparative Example 7:

[0190] The only difference from Example 5 is that in step (3), the amount of tungsten hydroxide used is 0.5% of the calcined product.

[0191] Comparative Example 8:

[0192] The only difference from Example 5 is that in step (3), the amount of tungsten hydroxide used is 0.03% of the calcined product.

[0193] Comparative Example 9:

[0194] The only difference from Example 5 is that in step (5), the amount of zirconium oxide used is 0.1% of the calcined product.

[0195] Comparative Example 10:

[0196] The only difference from Example 5 is that in step (5), the amount of zirconium oxide used is 0.5% of the calcined product.

[0197] Comparative Example 11:

[0198] The only difference from Example 5 is that in step (3), the evenly mixed sample is sintered at 900° C. in an air atmosphere for 5 h.

[0199] Comparative Example 12:

[0200] The only difference from Example 5 is that in step (3), the evenly mixed sample is sintered at 400° C. in an air atmosphere for 5 h.

[0201] Comparative Example 13:

[0202] The only difference from Example 5 is that in step (5), the dried product obtained in step (4) is evenly mixed with 0.20% zirconium oxide nanopowder, and then sintered at 750°C in an air atmosphere for 5 hours. After cooling to room temperature, the final product can be obtained.

[0203] Comparative Example 14:

[0204] The only difference from Example 5 is that the dried product obtained in step (4) is evenly mixed with 0.20% zirconium oxide nanopowder, and then sintered at 300°C in an air atmosphere for 5 hours. After cooling to room temperature, the final product can be obtained.

[0205] Test Case

[0206] The lithium-rich manganese-based positive electrode material, conductive carbon and binder obtained in the above examples and comparative examples were mixed in a ratio of 90:5:5 to prepare a slurry. The slurry was then coated on aluminum foil, dried, rolled and cut into pieces, and finally assembled with lithium sheets into button-type half-cells with a test range of 2.3-4.55V.

[0207] The discharge specific capacity and first coulombic efficiency of the assembled examples and comparative examples at 25° C. and 0.1C current density are shown in the table below.

[0208] The cycle performance of the button-type all-electric battery assembled in the embodiment and the comparative example under 1C conditions is shown in the table below.

[0209] As can be seen from the table above, direct coating after pickling destroys the substrate structure, leading to a significant decrease in high-rate cycling performance. At a rate of 1C, the capacity retention rate after 100 cycles was 65.9%. Pickling after coating the first coating layer and before coating the second coating layer significantly improved cycling performance at a rate of 1C, with the capacity retention rate reaching 85% after 100 cycles, a 20% improvement over the cycling performance of direct pickling and coating. This indicates that the second-sintered oxide coating helps maintain structural stability, reduces the damage to material properties caused by pickling, and thus improves cycling performance. Industrial Applicability

[0210] The double-coated lithium-manganese-rich cathode material provided herein first coats the surface of a lithium-manganese-rich cathode material with a metal oxide to form a first coating layer. The oxide has relatively good chemical stability and is not easily corroded. A second coating layer is then formed on top of the first coating layer, comprising one or more of a fluoride, oxide, and phosphate. The fluoride, oxide, and phosphate can enter the crystal lattice of the lithium-manganese-rich cathode material, occupying oxygen vacancies and inhibiting oxygen precipitation. This method for preparing the double-coated lithium-manganese-rich cathode material is simple, easy to implement, and has low manufacturing costs and good reproducibility, making it suitable for large-scale industrial production.

Claims

1. A double-coated lithium-rich manganese positive electrode material, characterized in that: It includes a core and a first coating layer and a second coating layer sequentially coated on the core. The core is a lithium-rich manganese-based cathode material. The first coating layer is an oxide of a first metal. The second coating layer is at least one of a fluoride of a second metal, an oxide of the second metal, and a phosphate of the second metal.

2. The double-coated lithium-rich manganese positive electrode material according to claim 1, characterized in that: The first metal is at least one of Al, W, Fe, Zr, and Ti.

3. The double-coated lithium-rich manganese positive electrode material according to claim 1 or 2, characterized in that: The second metal is at least one of Al, Zr, Sr, and Mg.

4. The double-coated lithium-rich manganese positive electrode material according to any one of claims 1 to 3, characterized in that: The mass of the first coating layer is 0.05% - 0.3% of the mass of the core.

5. The double-coated lithium-rich manganese positive electrode material according to any one of claims 1 to 4, characterized in that: The mass of the second coating layer is 0.15% - 0.3% of the mass of the core.

6. The double-coated lithium-rich manganese positive electrode material according to any one of claims 1 to 5, characterized in that: The average particle size is 2.5μm - 4μm.

7. The double-coated lithium-rich manganese positive electrode material according to any one of claims 1 to 6, characterized in that: The core is xLi2MnO3·(1 - x)LiMO2, where 0 < x < 1, and M is nickel and manganese.

8. The double-coated lithium-rich manganese positive electrode material according to claim 7, characterized in that: The oxide of the first metal and / or the oxide of the second metal is obtained by sintering the corresponding metal oxide, hydroxide, or oxyhydroxide.

9. A method for preparing the double-coated lithium-rich manganese positive electrode material according to any one of claims 1 to 8, characterized in that: It includes: The first coating step: coating the first coating layer on the surface of the lithium-rich manganese-based cathode material to obtain a single-coated lithium-rich manganese cathode material. The second coating step: coating the second coating layer on the single-coated lithium-rich manganese cathode material to obtain the double-coated lithium-rich manganese cathode material.

10. The method for preparing the double-coated lithium-rich manganese positive electrode material according to claim 9, characterized in that: In the first coating step, the lithium-rich manganese-based cathode material is mixed with the raw material of the first coating layer and subjected to a second sintering. The temperature of the second sintering is 500°C - 800°C, and the time is 5h - 8h.

11. The method for preparing the double-coated lithium-rich manganese positive electrode material according to claim 9 or 10, characterized in that: In the second coating step, the single-coated lithium-rich manganese cathode material is mixed with the raw material of the second coating layer and subjected to a third sintering. The temperature of the third sintering is 350°C - 650°C, and the time is 5h - 8h.

12. The method for preparing the double-coated lithium-rich manganese positive electrode material according to claim 11, characterized in that: Before performing the second coating, the single-coated lithium-rich manganese cathode material is pickled with a pickling solution.

13. The method for preparing the double-coated lithium-rich manganese positive electrode material according to claim 12, characterized in that: The pickling solution is an aqueous solution of a weak acid.

14. The method for preparing the double-coated lithium-rich manganese positive electrode material according to claim 13, characterized in that: The concentration of the weak acid in the aqueous solution of the weak acid is 0.01mol / L - 1mol / L.

15. The method for preparing the double-coated lithium-rich manganese positive electrode material according to claim 13 or 14, characterized in that: The weak acid is at least one of citric acid, phosphoric acid, hypochlorous acid, acetic acid, and formic acid.

16. The method for preparing a double-coated lithium-rich manganese positive electrode material according to any one of claims 12 to 15, characterized in that: In the pickling step, the liquid-solid ratio of the single-coated lithium-rich manganese cathode material to the pickling solution is (10:1 - 1:1) ml / g.

17. The method for preparing a double-coated lithium-rich manganese positive electrode material according to any one of claims 12 to 16, characterized in that: In the pickling step, after mixing the single-coated lithium-rich manganese cathode material with the pickling solution, it is stirred for 10min - 120min, then the single-coated lithium-rich manganese cathode material is separated, and the surface residual pickling solution is washed away with deionized water, and then dried before the second coating.

18. The method for preparing the double-coated lithium-rich manganese positive electrode material according to claim 17, characterized in that: The temperature of the drying step is 60°C - 100°C, and the time is 8h - 12h.

19. The method for preparing a double-coated lithium-rich manganese positive electrode material according to any one of claims 9 to 18, characterized in that: It also includes the preparation of the lithium-rich manganese-based cathode material: mixing the corresponding precursor of the lithium-rich manganese-based cathode material with a lithium salt and performing a first sintering to obtain the lithium-rich manganese-based cathode material.

20. The method for preparing the double-coated lithium-rich manganese positive electrode material according to claim 19, characterized in that: In the preparation step of the lithium-rich manganese-based cathode material, the molar ratio of lithium element to the total molar amount of manganese and nickel elements in the precursor is (1.1 - 1.65):

1.

21. The method for preparing the double-coated lithium-rich manganese positive electrode material according to claim 19 or 20, characterized in that: The temperature of the first sintering step is 750°C - 950°C, and the time is 8h - 15h.

22. The method for preparing a double-coated lithium-rich manganese positive electrode material according to any one of claims 19 to 21, characterized in that: The precursor is Ni 1-x Mn x (OH)2, wherein x = 0.4 to 0.

8.

23. An electrode, characterized in that: It includes the double-coated lithium-rich manganese cathode material according to any one of claims 1 - 8.

24. A battery, characterized in that: It includes the electrode according to claim 23.

25. An electrical device, characterized in that: It includes the battery according to claim 24.

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