Positive electrode active material and method for producing the same, positive electrode sheet, battery, and power consumption device

Abstract

A positive electrode active material and its manufacturing method, a positive electrode sheet, a battery, and a power consumption device, comprising a lithium-excess manganese-based positive electrode material and a coating layer distributed on at least a portion of the surface of the lithium-excess manganese-based positive electrode material, the coating layer containing at least one of a metal oxide and a metal fluoride, the specific capacity of the positive electrode active material being 220 mAh / g or more, and satisfying at least one of the following conditions: the oxygen vacancy index is 2.12 or more; the microscopic stress is 0.1% to 1.5%; the peak intensity ratio MO / Mn-O in the Fourier infrared spectrum is 25 to 40; and the specific surface area is 0.9 m 2 / g~3.5m 2 / g. By applying specific coatings to the lithium-rich manganese-based positive electrode material before and after acid washing, a positive electrode active material that meets a specific microscopic index range can be produced, resulting in a positive electrode active material with high specific capacity and good cycle stability.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority to a Chinese patent application entitled "Positive electrode active material and manufacturing method thereof, positive electrode sheet, battery, and power consumption device," filed on May 26, 2023, with application number 202310609601.1, the entire contents of which are incorporated herein by reference.

[0002] The present application relates to the field of battery technology, and more particularly to a positive electrode active material and a method for producing the same, a positive electrode sheet, a battery, and a power consuming device. [Background technology]

[0003] Currently, some solutions have adopted acid washing to improve the specific capacity of lithium-rich manganese-based positive electrode materials, but after washing, the cycle stability of the lithium-rich manganese-based positive electrode materials is reduced. Summary of the Invention

[0004] In view of the above problems, the present application provides a positive electrode active material and a manufacturing method thereof, a positive electrode sheet, a battery, and a power consumption device, in which a specific coating is applied to a lithium-excess manganese-based positive electrode material before and after acid washing, and the resulting positive electrode active material has high specific capacity and good cycle stability.

[0005] An embodiment of the present application is carried out as follows.

[0006] According to a first aspect, an embodiment of the present application provides a positive electrode active material including a lithium-rich manganese-based positive electrode material and a coating layer distributed on at least a portion of the surface of the lithium-rich manganese-based positive electrode material. The lithium-rich manganese-based positive electrode material includes an element M, where the element M includes one or more of Mg, Nb, Cr, Ce, Fe, Ta, B, Al, V, Ti, Zr, Sn, and Mo. The coating layer includes at least one of a metal oxide and a metal fluoride. The specific capacity of the positive electrode active material is 220 mAh / g or more, and the positive electrode active material satisfies at least one of the following conditions (a1) to (d1): (a1) In a refined X-ray diffraction spectrum of the positive electrode active material, the oxygen vacancy index is 2.12 or more; (b1) The microscopic stress of the positive electrode active material is 0.1% to 1.5%; and (c1) In a Fourier infrared spectrum of the positive electrode active material, the peak intensity ratio MO / Mn-O is 25 to 40. (d1) The specific surface area of ​​the positive electrode active material is 0.9 m 2 / g~3.5m 2 / g.

[0007] The positive electrode active materials provided in the examples of the present application have high specific capacity, and at the same time, at least one of the oxygen vacancy index, microscopic stress, peak intensity ratio MO / Mn-O, and specific surface area meets a specific range, so that the positive electrode active materials have good storage performance and cycle stability.

[0008] In some embodiments, the positive electrode active material satisfies at least one of the following conditions (a2) to (d2): (a2) In a refinement result of the X-ray diffraction spectrum of the positive electrode active material, the oxygen vacancy index is 2.72 or more; (b2) The microscopic stress of the positive electrode active material is 0.1% to 0.8%; (c2) In a Fourier infrared spectrum of the positive electrode active material, the peak intensity ratio MO / Mn-O is 30 to 40; (d2) The specific surface area of ​​the positive electrode active material is 1.5 m 2 / g~2.5m 2 In these examples, if at least one of the oxygen vacancy index, microscopic stress, peak intensity ratio MO / Mn-O, and specific surface area of ​​the positive electrode active material further satisfies the range, the positive electrode active material will have better storage performance and cycle stability.

[0009] In some embodiments, the coating layer has an elemental composition including one or more of Al, Ce, and Co, and one or more of Zr, B, and Ti. In these embodiments, the coating formed from the coating raw materials corresponding to Al, Ce, and Co can effectively protect the lithium-rich manganese-based positive electrode material during the acid pickling process, and the coating formed from the coating raw materials corresponding to Zr, B, and Ti can effectively modify the lithium-rich manganese-based positive electrode material after acid pickling, so that the coating layer can effectively improve the cycling stability of the positive electrode active material. At the same time, the B element can activate the lithium-containing rock salt phase on the surface of the material, which is beneficial to improving the specific capacity.

[0010] In some embodiments, the ratio of the total mass of Al and Ce to the total mass of Zr and B in the coating layer is 1:(0.5 to 2). In these embodiments, when the elements in the coating layer satisfy a specific ratio, the coating layer can more effectively improve the cycle stability of the positive electrode active material.

[0011] In some embodiments, the total content of Al, Ce, Co, Zr, B, and Ti in the coating layer of the positive electrode active material is 5000 ppm or less. In these embodiments, the content of the elements in the coating layer of the positive electrode active material is less than a certain range, so that the coating layer effectively improves the cycle stability of the positive electrode active material, and at the same time, the positive electrode active material has good specific capacity, which is advantageous for improving the initial coulombic efficiency of the battery.

[0012] In some embodiments, the coating layer includes one or more of aluminum fluoride, aluminum oxide, cerium fluoride, and cerium oxide, and one or more of zirconium oxide, zirconium fluoride, boric acid, and zirconium boride. In these embodiments, aluminum fluoride, aluminum oxide, cerium fluoride, and cerium oxide have high sintering temperature resistance and can coat the surface of the lithium-rich manganese-based positive electrode material in the form of a dense coating at high sintering temperatures, which can effectively protect the lithium-rich manganese-based positive electrode material during the acid washing process and is advantageous for improving cycle stability. Zirconium oxide, zirconium fluoride, boric acid, and zirconium boride can effectively modify the surface of the lithium-rich manganese-based positive electrode material and is advantageous for improving cycle stability, and can coat the surface of the lithium-rich manganese-based positive electrode material at low sintering temperatures and is advantageous for improving the specific capacity of the positive electrode active material and the initial coulombic efficiency of the battery.

[0013] In some embodiments, the ratio of the volumetric particle size distribution Dv50 of the lithium-rich manganese-based positive electrode material to the thickness of the coating layer is (5.5-6.5):(0.2-0.8). In these embodiments, when both the lithium-rich manganese-based positive electrode material and the coating layer have an appropriate size ratio, the coating layer effectively improves the cycling stability of the positive electrode active material, and the positive electrode active material has good specific capacity, which is advantageous for improving the initial coulombic efficiency of the battery.

[0014] In some embodiments, the thickness of the coating layer is 0.2 μm to 0.8 μm. In these embodiments, the coating layer has an appropriate thickness, which can effectively exert a protective effect and improve cycle stability, and is advantageous in improving the specific capacity of the positive electrode active material and the initial coulombic efficiency of the battery compared to when the coating layer is too thick.

[0015] In some embodiments, the lithium-rich manganese-based cathode material comprises Li[Li x Nia Co b Mn c M d ]O 2-e Contains x+a+b+c+d=1, x>0, a>0, 0 <b<0.1、c> 0, d≧0, 0≦e≦0.2. In these embodiments, the lithium-rich manganese-based positive electrode material has a low cobalt content, which can reduce costs.

[0016] According to a second aspect, an embodiment of the present application provides a method for manufacturing a cathode active material, the method including: coating a lithium-excess manganese-based cathode material with a primary coating raw material and sintering the material to obtain a primary coating material; washing the primary coating material with a solution containing an acid and / or an acid salt to obtain a primary coating pickled material; and coating the primary coating pickled material with a secondary coating raw material and sintering the material to obtain a cathode active material. The primary coating raw material includes one or more of a metal oxide and a metal fluoride, and the secondary coating raw material includes one or more of a metal oxide, a metal fluoride, and a boride.

[0017] The present invention provides a method for manufacturing a positive electrode active material, which improves the specific capacity by acid washing, uses a specific type of primary coating material before acid washing to protect the lithium-rich manganese-based positive electrode material and improve gas generation during the acid washing process, and uses a specific type of secondary coating material after acid washing to modify the surface of the lithium-rich manganese-based positive electrode material after acid washing. In this manufacturing method, the lithium-rich manganese-based positive electrode material is coated with a specific coating before and after acid washing to form a positive electrode active material that meets a specific microscopic index range, where the specific microscopic index includes at least one of the oxygen vacancy index, microscopic stress, peak intensity ratio MO / Mn-O, and specific surface area, and M is an optional doping element for the lithium-rich manganese-based positive electrode material, thereby providing the positive electrode active material with good storage performance and cycle stability.

[0018] In some embodiments, when the lithium-rich manganese-based positive electrode material is coated with a primary coating material and sintered, the sintering temperature is 500°C to 750°C, and optionally the sintering time is 6 hours to 12 hours. In these embodiments, selecting a relatively high specific sintering temperature after coating with the primary coating material helps to properly melt the primary coating material and stably coat it on the surface of the lithium-rich manganese-based positive electrode material, thereby better protecting the lithium-rich manganese-based positive electrode material during the acid cleaning process. Optionally, selecting an appropriate sintering time is advantageous for achieving both efficiency and sintering effect.

[0019] In some embodiments, the primary coating raw material comprises one or more of Al, Ce, and Co, and optionally comprises one or more of aluminum fluoride, aluminum oxide, cerium fluoride, and cerium oxide. In these embodiments, the primary coating raw material has a specific composition, which can form a dense coating on the surface of the lithium-excess manganese-based positive electrode material after sintering, can well protect the lithium-excess manganese-based positive electrode material, and is advantageous for improving cycle stability.

[0020] In some embodiments, the step of coating the primary coating acid-washed material with a secondary coating material and sintering the material involves a sintering temperature of 350°C to 550°C, and optionally a sintering time of 6 hours to 12 hours. In these embodiments, selecting a relatively low specific sintering temperature after coating with the secondary coating material can effectively melt the secondary coating material, thereby effectively modifying the surface of the lithium-excess manganese-based positive electrode material. Compared to a too high sintering temperature, this can also prevent the surface defect spinel structure from converting to a rock salt phase, which is advantageous for improving the specific capacity of the positive electrode active material and the initial coulombic efficiency of the battery. Optionally, selecting an appropriate sintering time can be advantageous for achieving both efficiency and sintering effect.

[0021] In some embodiments, the secondary coating raw material includes one or more of Zr, B, and Ti, and optionally includes one or more of zirconium oxide, zirconium fluoride, boric acid, and zirconium boride. In these embodiments, the secondary coating raw material has a specific composition, which can effectively modify the surface of the lithium-excess manganese-based positive electrode material, which is advantageous for improving cycle stability, and can coat the surface of the lithium-excess manganese-based positive electrode material at a low sintering temperature, which is advantageous for improving the specific capacity of the positive electrode active material and the initial coulombic efficiency of the battery.

[0022] In some embodiments, the primary coating material comprises one or more of aluminum fluoride, aluminum oxide, cerium fluoride, and cerium oxide, the secondary coating material comprises one or more of zirconium oxide, zirconium fluoride, boric acid, and zirconium boride, and the ratio of the total mass of Al and Ce in the primary coating material to the total mass of Zr and B in the secondary coating material is 1:(0.5 to 2). In these embodiments, when the compositions of the primary coating material and the secondary coating material satisfy a specific ratio, the coating layer can more effectively improve the cycling stability of the positive electrode active material.

[0023] In some embodiments, the primary coating material comprises one or more of Al, Ce, and Co, the secondary coating material comprises one or more of Zr, B, and Ti, the primary coating material and the secondary coating material form a coating layer distributed on at least a portion of the surface of the lithium-rich manganese-based positive electrode material, and the total content of Al, Ce, Co, Zr, B, and Ti in the coating layer in the positive electrode active material is 5000 ppm or less. In these embodiments, the content of the elements of the coating layer in the positive electrode active material is less than a certain range, so that the coating layer effectively improves the cycling stability of the positive electrode active material, and at the same time, the positive electrode active material has good specific capacity, which is advantageous for improving the initial coulombic efficiency of the battery.

[0024] In some embodiments, the primary coating material and the secondary coating material form a coating layer distributed on at least a portion of the surface of the lithium-excess manganese-based positive electrode material, and the coating layer has a thickness of 0.2 μm to 0.8 μm. In these embodiments, the coating layer has an appropriate thickness, which can effectively exert a protective effect and improve cycle stability, and is advantageous in improving the specific capacity of the positive electrode active material and the initial coulombic efficiency of the battery compared to when the coating layer is too thick.

[0025] In some embodiments, the lithium-rich manganese-based cathode material comprises Li[Li x Ni a Co b Mn c M d ]O 2-eContains x+a+b+c+d=1, x>0, a>0, 0 <b<0.1、c> 0, d≧0, 0≦e≦0.2, and the element M includes one or more of Mg, Nb, Cr, Ce, Fe, Ta, B, Al, V, Ti, Zr, Sn, and Mo. In these embodiments, the lithium-rich manganese-based positive electrode material has a low cobalt content, which can reduce costs, and having the specific doping element M in the lithium-rich manganese-based positive electrode material is advantageous for improving the specific capacity of the positive electrode active material and the initial coulombic efficiency of the battery.

[0026] In some embodiments, in the step of washing the primary coating material with a solution containing an acid and / or an acid salt, the solution containing an acid and / or an acid salt comprises an organic acid and / or an organic acid salt, the pH value of the solution containing the acid and / or the acid salt is 2 to 8, the washing time is 0.25 hours to 4 hours, and optionally the solution containing the acid and / or the acid salt comprises one or more of citric acid, ammonium citrate, and diammonium hydrogen citrate. In these embodiments, performing the acid washing under certain pH value and washing time conditions can significantly improve the specific capacity of the positive electrode active material and the initial coulombic efficiency of the battery.

[0027] According to a third aspect, an embodiment of the present application provides a positive electrode sheet including the positive electrode active material of the above embodiment or the positive electrode active material obtained by the method for producing the positive electrode active material of the above embodiment.

[0028] According to a fourth aspect, an embodiment of the present application provides a battery including the positive electrode sheet of the above embodiment.

[0029] According to a fifth aspect, an embodiment of the present application provides a power consuming device including the battery of the above embodiment.

[0030] The above description is only a summary of the technical solutions of the embodiments of the present application. In order to more clearly understand the technical solutions of the present application, the following specific embodiments of the present application are given, which can be implemented according to the content of the specification, and to more clearly understand the above and other objectives, features and advantages of the present application.

[0031] In order to more clearly explain the technical solutions of the embodiments of the present application, the following briefly describes the drawings that need to be used in the embodiments. The following drawings only illustrate some embodiments of the present application, and should not be considered as limiting the scope. It should be understood that those skilled in the art can derive other related drawings based on these drawings without any creative efforts. [Brief explanation of the drawings]

[0032] [Figure 1] 1 is a structural schematic diagram of a vehicle according to some embodiments of the present application. [Figure 2] FIG. 1 is an exploded view of a battery according to some embodiments of the present application. [Figure 3] FIG. 1 is an exploded view of a battery cell according to some embodiments of the present application. [Figure 4] 1 is a structural schematic diagram of an electrode assembly according to some embodiments of the present application. [Figure 5] 1 is a process flow chart of a method for manufacturing a cathode active material according to some embodiments of the present application. [Explanation of symbols]

[0033] 1000-vehicles, 100-battery, 200-controller, 300-motor, 10—casing, 11—first part, 12—second part, 13—accommodation space, 20—battery cell; 21—outer case; 22—electrode assembly; 23—electrode terminal; 24—decompression structure; 211 - housing, 212 - cover, 213 - sealed space, 221 - positive electrode sheet, 222 - negative electrode sheet, 223 - separator. DETAILED DESCRIPTION OF THE INVENTION

[0034] In order to clarify the objectives, technical solutions and advantages of the examples of this application, the technical solutions in the examples of this application are clearly and completely explained. If specific conditions are not specified in the examples, they are carried out under general conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or equipment used is not listed, they are all common products available on the market.

[0035] The following detailed description will be given of the embodiments of the technical solution of the present application with reference to the drawings. The following embodiments are only used to more clearly explain the technical solution of the present application, and are merely examples, which do not limit the scope of protection of the present application.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs, and the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The terms "including" and "having" and their variants in the specification and claims of this application, as well as the description of the drawings above, are intended to be non-exclusive.

[0037] In describing the embodiments of the present application, technical terms such as "first," "second," etc. are merely used to distinguish between different objects, and should not be understood as indicating or implying relative importance, or implying the quantity, specific order, or hierarchical relationship of the technical features shown.

[0038] In the description of the embodiments of the present application, the term "and / or," e.g., "Feature 1 and / or Feature 2," may refer to "Feature 1" individually, or to "Feature 2" individually, or to "Feature 1" plus "Feature 2." Note that in this specification, the symbol " / " generally indicates that the related objects before and after it are in an "or" relationship.

[0039] In the description of the embodiments of the present application, unless otherwise specified, the term "plurality" as used in "one or more" refers to two and more than two.

[0040] References to "an embodiment" herein mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present application. Appearances of the term "embodiment" in various places in this specification do not necessarily refer to the same embodiment, nor do they refer to embodiments that are mutually exclusive, independent, or alternative to other embodiments. Those skilled in the art will understand, both explicitly and implicitly, that the embodiments described herein can be combined with other embodiments.

[0041] In the embodiments of the present application, the same reference numerals indicate the same elements, and detailed descriptions of the same elements will be omitted in different embodiments for the sake of brevity. Note that the dimensions such as height, length, and width of each element in the embodiments of the present application and the overall dimensions such as height, length, and width of the stacking device shown in the drawings are merely illustrative and do not limit the present application in any way.

[0042] With the development of the market situation, the application of power batteries is becoming more and more widespread. Power batteries are not only used in energy storage power systems such as hydroelectric power, thermal power, wind power and solar power plants, but are also widely used in electric vehicles such as electric bicycles, electric motorcycles and electric cars, as well as in military equipment and aerospace, among other fields. As the application fields of power batteries continue to expand, the demand for them in the market is also constantly increasing.

[0043] With the continuous development of the new energy industry, the market is showing more diversified needs for positive electrode active materials. Lithium-excess manganese-based positive electrode active materials have attracted attention due to their advantages such as high voltage, high specific capacity, excellent safety, abundant resources, and low pollution, and are regarded as a potential next-generation positive electrode active material.

[0044] Improving the specific capacity of positive electrode active materials and the initial coulombic efficiency of batteries is a current research trend. In particular, considering cost reduction, some studies have begun to use low-cobalt-content lithium-rich manganese-based positive electrode materials. However, because low-cobalt-content lithium-rich manganese-based positive electrode materials result in a decrease in specific capacity, it is now considered more important to effectively improve the specific capacity.

[0045] To improve the specific capacity and initial coulombic efficiency of lithium-rich manganese-based positive electrode materials, some solutions have treated them with a washing method. Some technical solutions use alkaline washing, which uses a metaaluminate solution or a pyrophosphate solution as the treatment solution. However, this alkaline washing method not only increases the pH and increases the residual alkali content, but also introduces new impurity ions such as sodium, which affect the performance of the positive electrode active material. Due to the above-mentioned drawbacks of alkaline washing, some technical solutions use acid washing, which uses a solution containing an acid and / or an acid salt as the treatment solution. However, this acid washing method easily damages the surface of the lithium-rich manganese-based positive electrode material, thereby reducing the cycling stability of the lithium-rich manganese-based positive electrode material.

[0046] In view of this, the present invention provides a cathode active material and a manufacturing method thereof. A lithium-rich manganese-based cathode material is washed by acid washing. Based on this, a specific coating is applied to the lithium-rich manganese-based cathode material before and after acid washing. The M element is an optional doping element of the lithium-rich manganese-based cathode material to form a cathode active material that satisfies a specific microscopic index range. The specific microscopic index includes at least one of an oxygen vacancy index, a microscopic stress, a peak intensity ratio MO / Mn-O, and a specific surface area. A suitable oxygen vacancy index is beneficial for reducing the deterioration of oxygen release caused by oxygen vacancies. A suitable microscopic stress can improve the particle rupture caused by the generation and release of residual stress during cycling. A suitable MO / Mn-O peak intensity ratio indicates good coating protection, which can improve the long-term storage and cycling performance of the battery. A suitable specific surface area can combine good capacity performance, good storage performance, and low gas generation related to side reactions, resulting in a cathode active material with good storage performance and cycling stability. Therefore, in the technical solution provided by the embodiments of the present application, a specific coating is applied to the lithium-excess manganese-based positive electrode material before and after acid washing, and the resulting positive electrode active material not only has a high specific capacity and is beneficial to improving the initial coulombic efficiency of the battery, but also has good cycle stability.

[0047] The battery cells using the positive electrode sheets disclosed in the embodiments of the present application can be used in power consumption devices such as, but not limited to, vehicles, ships, and aircraft. The embodiments of the present application provide a battery-powered power consumption device, which can be, but is not limited to, a mobile phone, a tablet, a laptop, an electric toy, a power tool, a battery car, an electric vehicle, a ship, a spacecraft, etc. The electric toy can include a stationary or mobile electric toy such as a game console, an electric car toy, an electric ship toy, and an electric aircraft toy, and the spacecraft can include an aircraft, a rocket, a space shuttle, a spaceship, etc.

[0048] In the following embodiments, for convenience of explanation, the power consumption device of the embodiment of the present application will be described as a vehicle.

[0049] Referring to FIG. 1, FIG. 1 is a structural schematic diagram of a vehicle 1000 according to some embodiments of the present application. The vehicle 1000 may be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle, a range-extender vehicle, etc. A battery 100 is provided inside the vehicle 1000, and the battery 100 may be provided at the bottom, front, or rear of the vehicle 1000. The battery 100 can be used to power the vehicle 1000, for example, the battery 100 can be an operating power source for the vehicle 1000. The vehicle 1000 may further include a controller 200 and a motor 300, where the controller 200 is for powering the motor 300 and controlling the battery 100 to meet operating power consumption needs, for example, for starting, navigating, and driving the vehicle 1000.

[0050] In some embodiments of the present application, the battery 100 can provide not only the operating power source for the vehicle 1000 but also the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0051] In this application, battery 100 refers to a single physical module including one or more battery cells 20 to provide higher voltage and capacity, and may be in the form of a battery pack, a battery module, etc. Battery 100 may include a housing 10 for packaging one or more battery cells 20, and housing 10 can prevent liquids or other foreign objects from affecting the charging and discharging of battery cells 20.

[0052] Referring to FIG. 2, FIG. 2 is an exploded view of a battery 100 according to some embodiments of the present application. The battery 100 includes a housing 10 and a plurality of battery cells 20, which are housed in the housing 10. The housing 10 is used to house the battery cells 20, and the housing 10 may have various structures. In some embodiments, the housing 10 may include a first portion 11 and a second portion 12, which are fitted together to define a housing space 13 for housing the battery cells 20. The second portion 12 may have a hollow structure with one end open, and the first portion 11 may have a plate-like structure, and the first portion 11 is fitted over the open side of the second portion 12 to form the housing 10 having the housing space 13. Alternatively, both the first part 11 and the second part 12 may have a hollow structure with one side open, and the open side of the first part 11 covers the open side of the second part 12 to form a housing 10 having an accommodation space 13. The first part 11 and the second part 12 may have various shapes such as a cylinder or a rectangular parallelepiped.

[0053] In the battery 100, the plurality of battery cells 20 can be connected in series, in parallel, or in series-parallel, and a series-parallel connection refers to not only a series connection but also a parallel connection between the plurality of battery cells 20. The plurality of battery cells 20 may be directly connected in series, in parallel, or in series-parallel, and a unit formed of the plurality of battery cells 20 may be housed in the housing 10. The plurality of battery cells 20 may first be connected in series, in parallel, or in series-parallel to form a module, and the plurality of modules may then be connected in series, in parallel, or in series-parallel to form a unit that is housed in the housing 10. The battery 100 may further include other structures; for example, the plurality of battery cells 20 may be electrically connected by a bus member, thereby realizing the series, parallel, or series-parallel connection of the plurality of battery cells 20.

[0054] The battery cell 20 refers to the smallest unit that constitutes a battery pack. The battery cell 20 may be, but is not limited to, a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery.

[0055] Referring to FIG. 3, the battery cell 20 may include an outer case 21 , an electrode assembly 22 and an electrolyte, and the electrode assembly 22 and the electrolyte are both housed in the outer case 21 .

[0056] The outer case 21 may include a housing 211 and a cover 212. The housing 211 is an assembly that mates with the end cover 212 to form an internal sealed space 213 of the battery cell 20, and the formed sealed space 213 can be used to accommodate the electrode assembly 22, an electrolyte, and other components. The cover 212 is a member that is placed over the opening of the housing 211 to isolate the internal environment of the battery cell 20 from the external environment. The shape of the cover 212 can be adapted to the shape of the housing 211 to be combined with the housing 211, and the cover 212 may further be provided with functional components such as an electrode terminal 23 and a pressure reduction structure 24. A seal ring can be provided between the opening of the housing 211 and the cover 212 to achieve a seal between the housing 211 and the cover 212.

[0057] The housing 211 and the cover 212 may have various shapes and sizes, such as a rectangular parallelepiped, a cylinder, or a hexagonal prism. Specifically, the shapes of the housing 211 and the cover 212 are determined depending on the specific shape and size of the electrode assembly 22. The housing 211 and the cover 212 may be made of various materials, including, but not limited to, metals such as copper, iron, aluminum, stainless steel, and aluminum alloys. The seal ring may be made of various materials, including, but not limited to, electrolyte corrosion-resistant, highly tough, and fatigue-resistant materials such as PP (polypropylene), PC (polycarbonate), and PET (polyethylene terephthalate). A plating layer may be formed on the outer surface of the housing 211, and the plating layer may be made of various materials, including, but not limited to, corrosion-resistant materials such as Ni and Cr.

[0058] The battery cell 20 may be in the form of a soft pack, such as a pouch-type soft pack. The soft pack may be made of plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0059] 4 , the electrode assembly 22 includes a negative electrode sheet 222, a separator 223, and a positive electrode sheet 221. The battery cell 20 operates mainly by the movement of metal ions between the positive electrode sheet 221 and the negative electrode sheet 222. During charging and discharging, active ions are inserted and removed between the positive electrode sheet 221 and the negative electrode sheet 222. The separator 223, located between the positive electrode sheet 221 and the negative electrode sheet 222, primarily serves to prevent short-circuiting between the positive and negative electrodes while allowing ions to pass through. The electrode assembly 22 may have a wound structure or a stacked structure, although the present application is not limited thereto.

[0060] The negative electrode sheet 222 includes a negative electrode current collector and a negative electrode active material layer, and the negative electrode active material layer is provided on at least one side of the negative electrode current collector, and a primer layer or the like may further be provided between the negative electrode current collector and the negative electrode active material layer.

[0061] A metal foil or a composite current collector may be used as the negative electrode current collector. For example, the material of the negative electrode current collector may be copper. The composite current collector may include a polymer material base layer and a metal layer formed on at least one side of the polymer material base layer. The composite current collector can be formed by forming a layer of a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a polymer material substrate (a substrate such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0062] The negative electrode active material in the negative electrode active material layer may be a negative electrode active material such as carbon or silicon. For example, the negative electrode active material may include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material may be selected from at least one of silicon element, silicon oxide, silicon carbon composite, silicon nitrogen composite, and silicon alloy. The tin-based material may be selected from at least one of tin element, tin oxide compound, and tin alloy. However, the present application is not limited to these materials, and other conventional materials usable as negative electrode active materials may also be used.

[0063] In some embodiments, the negative electrode active material layer may further include a binder, which may be selected from at least one of styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0064] In some embodiments, the negative electrode active material layer may further include a conductive agent, which may be selected from the group consisting of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0065] In some embodiments, the negative electrode active material layer optionally further comprises other auxiliary agents such as a thickener (eg, carboxymethylcellulose sodium (CMC-Na)).

[0066] The separator 223 is located between the positive electrode sheet 221 and the negative electrode sheet 222 and serves to separate them. The present application does not particularly limit the type of separator 223, and any known porous structure separator 223 having good chemical stability and mechanical stability can be selected.

[0067] In some embodiments, the material of separator 223 can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. Separator 223 may be a single-layer film or a multi-layer composite film, and is not particularly limited. When separator 223 is a multi-layer composite film, the materials of each layer may be the same or different, and are not particularly limited.

[0068] The positive electrode sheet 221 includes a positive electrode current collector and a positive electrode active material layer, and the positive electrode active material layer is provided on at least one side of the positive electrode current collector, and a primer layer or the like may further be provided between the positive electrode active material layer and the positive electrode current collector.

[0069] The positive electrode current collector can be a metal foil or a composite current collector, and for example, the material of the positive electrode current collector can be aluminum. The composite current collector can include a polymer material base layer and a metal layer formed on at least one side of the polymer material base layer, and can be formed by forming a layer of a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a polymer material substrate (e.g., a substrate such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0070] The positive electrode active material layer may include the positive electrode active material according to the embodiment of the present application or the positive electrode active material manufactured by the method for manufacturing the positive electrode active material according to the embodiment of the present application, and may further include other types of active materials such as lithium cobalt oxide, lithium iron phosphate, ternary lithium, lithium manganese oxide, and lithium sulfur.

[0071] In some embodiments, the positive electrode active material layer may further include a binder. For example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0072] In some embodiments, the positive electrode active material layer may further include a conductive agent, for example, at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0073] Next, the positive electrode active material and the manufacturing method thereof according to the examples of the present application will be described in detail.

[0074] According to a first aspect, an embodiment of the present application provides a positive electrode active material including a lithium-rich manganese-based positive electrode material and a coating layer distributed on at least a portion of the surface of the lithium-rich manganese-based positive electrode material. The lithium-rich manganese-based positive electrode material includes an element M, where the element M includes one or more of Mg, Nb, Cr, Ce, Fe, Ta, B, Al, V, Ti, Zr, Sn, and Mo. The coating layer includes at least one of a metal oxide and a metal fluoride. The specific capacity of the positive electrode active material is 220 mAh / g or more, and the positive electrode active material satisfies at least one of the following conditions (a1) to (d1): (a1) In a refined X-ray diffraction spectrum of the positive electrode active material, the oxygen vacancy index is 2.12 or more; (b1) The microscopic stress of the positive electrode active material is 0.1% to 1.5%; and (c1) In a Fourier infrared spectrum of the positive electrode active material, the peak intensity ratio MO / Mn-O is 25 to 40. (d1) The specific surface area of ​​the positive electrode active material is 0.9 m 2 / g~3.5m 2 / g.

[0075] As an example, the battery 100 including the positive electrode active material satisfies an initial coulombic efficiency of 84% or more.

[0076] The lithium-rich manganese-based positive electrode material may include a mixture and / or solid solution of Li2MnO3 phase and a layered structure of lithium nickel cobalt manganese oxide. The M element may be, for example, a doping element in the lithium-rich manganese-based positive electrode material.

[0077] The coating layer is distributed on at least a portion of the surface of the lithium-rich manganese-based positive electrode material, i.e., the coating layer may locally coat the surface of the lithium-rich manganese-based positive electrode material, or may coat the entire surface of the lithium-rich manganese-based positive electrode material. In a structure in which the coating layer coats at least a portion of the surface of the lithium-rich manganese-based positive electrode material, the coating material of the coating layer is, for example, distributed mainly in an island form on the surface of the lithium-rich manganese-based positive electrode material, and some of the coating material is observed to be distributed in the form of small particles in a dotted pattern on the surface of the main material between the coating layer and the lithium-rich manganese-based positive electrode material, and the interface between the two can be defined by a common method, for example, by directly observing the materials with an electron microscope, for example, by observing with a transmission electron microscope.

[0078] The specific capacity and initial coulombic efficiency can be obtained by conventional testing methods. For example, a battery is charged at a 0.1C rate from a voltage of 2.5V to 4.55V up to 4.55V, then charged at a constant voltage of 4.55V until the current drops to 0.05mA or less, and allowed to stand for 2 minutes. The charge capacity at this point is designated as C0. The battery is then discharged at a 0.1C rate down to 2.5V. The discharge capacity at this point is designated as DO, which is the specific capacity. The initial coulombic efficiency is DO / CO * 100%.

[0079] JPEG2026500730000002.jpg51165

[0080] As an example, the oxygen deficiency index is, for example, 2.2 or more, 2.3 or more, 2.4 or more, 2.5 or more, 2.6 or more, 2.7 or more, 2.8 or more, 2.9 or more, 3.0 or more, 3.1 or more, etc., but is not limited to these.

[0081] The microscopic stress of the positive electrode active material can be obtained by testing using a conventional method. For example, the microscopic stress of the positive electrode active material can be calculated as (β hkl *cosθ hkl ) / (4sinθ hkl ) θ hkl is the diffraction angle of the (hkl) crystal plane diffraction peak of the lithium-rich manganese-based positive electrode material in the XRD diffraction pattern, and β hkl is the full width at half maximum of the (hkl) crystal plane diffraction peak of the lithium-excess manganese-based positive electrode material in the XRD diffraction pattern.

[0082] As an example, the microscopic stress of the positive electrode active material may be, for example, but not limited to, any one of 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, and 1.5%, or a range between any two of these values.

[0083] The Fourier infrared spectrum, also known as a Fourier transform infrared spectrum (FTIR), can be obtained by using a Fourier transform infrared spectrometer and testing methods known in the art, specifically referring to the national standard GB / T6040-2002. The peak intensity ratio MO / Mn-O refers to the ratio of the peak intensity of the absorption peak corresponding to MO to the peak intensity of the absorption peak corresponding to Mn-O. The peak intensity of the absorption peak corresponding to MO is the peak intensity of the absorption peak at the position corresponding to MO, and the peak intensity of the absorption peak corresponding to Mn-O is the peak intensity of the absorption peak at the position corresponding to Mn-O.

[0084] For example, the peak intensity ratio MO / Mn—O may be, but is not limited to, any one of 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, and 40 or a range between any two of these values.

[0085] The specific surface area (BET) refers to the total area of ​​a material per unit mass. The specific surface area of ​​the positive electrode active material can be determined by conventional testing methods, for example, see the national standard GB / T 19587-2004.

[0086] As an example, the specific surface area of ​​the positive electrode active material is 0.9 m 2 / g, 1m 2 / g, 1.1m 2 / g, 1.2m 2 / g, 1.3m 2 / g, 1.4m 2 / g, 1.5m 2 / g, 1.6m 2 / g, 1.7m 2 / g, 1.8m 2 / g, 1.9m 2 / g, 2m 2 / g, 2.1m 2 / g, 2.2m 2 / g, 2.3m 2 / g, 2.4m 2 / g, 2.5m 2 / g, 2.6m 2 / g, 2.7m 2 / g, 2.8m 2 / g, 2.9m 2 / g, 3m 2 / g, 3.1m 2 / g, 3.2m 2 / g, 3.3m 2 / g, 3.4m 2 / g and 3.5m 2 / g or a range between any two of these values, but are not limited to these.

[0087] The positive electrode active materials provided in the examples of the present application have high specific capacity, and at the same time, at least one of the oxygen vacancy index, microscopic stress, peak intensity ratio MO / Mn-O, and specific surface area meets a specific range, so that the positive electrode active materials have good storage performance and cycle stability.

[0088] In some embodiments, the positive electrode active material satisfies at least one of the following conditions (a2) to (d2): (a2) In a refinement result of the X-ray diffraction spectrum of the positive electrode active material, the oxygen vacancy index is 2.72 or more; (b2) The microscopic stress of the positive electrode active material is 0.1% to 0.8%; (c2) In a Fourier infrared spectrum of the positive electrode active material, the peak intensity ratio MO / Mn-O is 30 to 40; (d2) The specific surface area of ​​the positive electrode active material is 1.5 m 2 / g~2.5m 2 / g.

[0089] In these examples, if at least one of the oxygen vacancy index, microscopic stress, peak intensity ratio MO / Mn-O, and specific surface area of ​​the positive electrode active material further satisfies the range, the positive electrode active material will have better storage performance and cycle stability.

[0090] In some embodiments, in the coating layer, the elemental composition includes one or more of Al, Ce, and Co elements, and one or more of Zr, B, and Ti elements.

[0091] In the coating layer, the metal oxide and metal fluoride refer to the composition type of the compound therein, and the element composition refers to the element composition of the compound in the coating layer. For example, the metal oxide and / or metal fluoride may contain one or more of Al element, Ce element, and Co element.

[0092] In these examples, the coatings formed from the coating raw materials corresponding to Al, Ce, and Co elements can effectively protect the lithium-excess manganese-based positive electrode material during the acid pickling process, and the coatings formed from the coating raw materials corresponding to Zr, B, and Ti elements can effectively modify the lithium-excess manganese-based positive electrode material after acid pickling, so that the coating layer can effectively improve the cycle stability of the positive electrode active material. At the same time, the B element can activate the lithium-containing rock salt phase on the surface of the material, which is beneficial to improving the specific capacity.

[0093] In some embodiments, the ratio of the total mass of Al and Ce elements to the total mass of Zr and B elements in the coating layer is 1:(0.5-2).

[0094] The masses of Al, Ce, Zr and B elements can be obtained by testing using conventional methods, for example, by measuring them using EPA6010d-2014 inductively coupled plasma atomic emission spectrometry.

[0095] As an example, the ratio of the total mass of Al and Ce elements to the total mass of Zr and B elements may be, but is not limited to, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2, etc.

[0096] In these embodiments, when the elements in the coating layer satisfy a specific ratio, the coating layer can more effectively improve the cycle stability of the positive electrode active material.

[0097] In some embodiments, in the positive electrode active material, the total content of Al, Ce, Co, Zr, B, and Ti elements in the coating layer is ≦5000 ppm.

[0098] The total content of Al, Ce, Co, Zr, B and Ti in the coating layer can be determined by conventional testing methods, for example, by measuring it using EPA6010d-2014 inductively coupled plasma atomic emission spectroscopy.

[0099] As an example, the total content of Al, Ce, Co, Zr, B and Ti elements in the coating layer may be, but is not limited to, any one of 1000 ppm, 2000 ppm, 3000 ppm, 4000 ppm and 5000 ppm, or a range between any two of these values.

[0100] In these embodiments, when the content of the element composition of the coating layer in the positive electrode active material is less than a certain range, the coating layer effectively improves the cycle stability of the positive electrode active material, and at the same time, the positive electrode active material has good specific capacity, which is advantageous for improving the initial coulombic efficiency of the battery 100.

[0101] In some embodiments, the coating layer comprises one or more of aluminum fluoride, aluminum oxide, cerium fluoride, and cerium oxide, and one or more of zirconium oxide, zirconium fluoride, boric acid, and zirconium boride.

[0102] In these embodiments, aluminum fluoride, aluminum oxide, cerium fluoride, and cerium oxide have high sintering temperature resistance and can coat the surface of the lithium-rich manganese-based positive electrode material in the form of a dense coating at high sintering temperatures, which can effectively protect the lithium-rich manganese-based positive electrode material during the acid washing process and is advantageous for improving cycle stability. Zirconium oxide, zirconium fluoride, boric acid, and zirconium boride can effectively modify the surface of the lithium-rich manganese-based positive electrode material and are advantageous for improving cycle stability, and can coat the surface of the lithium-rich manganese-based positive electrode material at low sintering temperatures and are advantageous for improving the specific capacity of the positive electrode active material and the initial coulombic efficiency of the battery 100.

[0103] In some embodiments, the ratio of the volumetric particle size distribution Dv50 of the lithium-excess manganese-based positive electrode material to the thickness of the coating layer is (5.5-6.5):(0.2-0.8).

[0104] The volumetric particle size distribution Dv50 refers to the particle size corresponding to 50% of the volume distribution, which can be obtained by conventional testing methods, for example, referring to the national standard GB / T 19077-2016 / ISO13320:2009 particle size distribution laser diffraction method, using a Malvern 3000 instrument for measurement.

[0105] The thickness of the coating layer is the value of the wall thickness from the inner surface to the outer surface of the coating layer, and is obtained by measuring the distance from the inner surface to the outer surface of the coating layer at multiple positions in an electron microscope photograph of a cut surface of the positive electrode active material and taking the average value.

[0106] The volumetric particle size distribution Dv50 of the lithium-excess manganese-based positive electrode material is measured by a particle size distribution laser diffraction method, and then the volumetric particle size distribution Dv50 of the lithium-excess manganese-based positive electrode material is obtained by subtracting twice the thickness of the coating layer from the volumetric particle size distribution Dv50 of the positive electrode active material.

[0107] As an example, the ratio of the volumetric particle size distribution Dv50 of the lithium-excess manganese-based positive electrode material to the thickness of the coating layer is 5.5:(0.2 to 0.8), 6:(0.2 to 0.8), 6.5:(0.2 to 0.8), etc., but is not limited to these.

[0108] In these embodiments, when both the lithium-excess manganese-based positive electrode material and the coating layer have an appropriate size ratio, the coating layer can effectively improve the cycling stability of the positive electrode active material, and at the same time, the positive electrode active material has a good specific capacity, which is advantageous for improving the initial coulombic efficiency of the battery 100.

[0109] In some embodiments, the coating layer has a thickness of 0.2 μm to 0.8 μm.

[0110] By way of example, the thickness of the coating layer may be, but is not limited to, any one of 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, and 0.8 μm, or a range between any two of these values.

[0111] In these embodiments, when the coating layer has an appropriate thickness, it can effectively exert a protective effect and improve cycle stability, and is advantageous in improving the specific capacity of the positive electrode active material and the initial coulombic efficiency of the battery 100 compared to when the coating layer is too thick.

[0112] In some embodiments, the lithium-rich manganese-based cathode material comprises Li[Li x Ni a Co b Mn c M d ]O 2-e Contains x+a+b+c+d=1, x>0, a>0, 0 <b<0.1、c> 0, d≧0, 0≦e≦0.2.

[0113] In lithium-excess manganese-based positive electrode materials, the chemical formula is Li[Li x Ni a Co b Mn c M d ]O 2-e can be measured by a conventional method, for example, by using ICP optical emission spectrometry (inductively coupled plasma optical emission spectrometer).

[0114] In addition, as the positive electrode sheet 221, the battery cell 20, and the power consumption device go through cycles and other processes, oxygen elements in the positive electrode active material are lost, which may result in a situation where the measured oxygen element content in the positive electrode active material decreases.

[0115] In these examples, the lithium-rich manganese-based cathode materials have a low cobalt content, which can reduce costs.

[0116] 5 , according to a second aspect, an embodiment of the present application provides a method for manufacturing a cathode active material, the method including: coating a lithium-excess manganese-based cathode material with a primary coating raw material and sintering the material to obtain a primary coating material; washing the primary coating material with a solution containing an acid and / or an acid salt to obtain a primary coating pickled material; and coating the primary coating pickled material with a secondary coating raw material and sintering the material to obtain a cathode active material. The primary coating raw material includes one or more of a metal oxide and a metal fluoride, and the secondary coating raw material includes one or more of a metal oxide, a metal fluoride, and a boride.

[0117] The method for producing a positive electrode active material according to the embodiment of the present application is exemplarily used to produce a positive electrode active material according to the embodiment of the first aspect.

[0118] Regarding the selection of raw materials, the size, element composition, dosage ratio, etc. of the lithium-rich manganese-based positive electrode material, the primary coating raw material, and the secondary coating raw material can all be selected with reference to the positive electrode active material according to the first aspect. Illustratively, the lithium-rich manganese-based positive electrode material includes an M element, which includes one or more of Mg, Nb, Cr, Ce, Fe, Ta, B, Al, V, Ti, Zr, Sn, and Mo.

[0119] Regarding the performance of the manufactured product, for example, the specific capacity of the positive electrode active material is 220 mAh / g or more. At the same time, the positive electrode active material satisfies at least one of the following conditions (a1) to (d1): (a1) In the refinement result of the X-ray diffraction spectrum of the positive electrode active material, the oxygen vacancy index is 2.12 or more. (b1) The microscopic stress of the positive electrode active material is 0.1% to 1.5%. (c1) In the Fourier infrared spectrum of the positive electrode active material, the peak intensity ratio MO / Mn-O is 25 to 40. (d1) The specific surface area of ​​the positive electrode active material is 0.9 m 2 / g~3.5m2 / g. Also, exemplarily, the battery 100 including the positive electrode active material satisfies an initial coulombic efficiency of 84% or more.

[0120] In addition, the terms primary and secondary in the primary coating material and secondary coating material do not refer to the number of coatings or the number of times the coating has been repeated, but merely distinguish between coatings at different times.

[0121] The present invention provides a method for manufacturing a positive electrode active material by acid washing to improve the specific capacity, coating the lithium-rich manganese-based positive electrode material with a specific type of primary coating material before acid washing to protect the material and improve gas generation during the acid washing process, and coating the lithium-rich manganese-based positive electrode material with a specific type of secondary coating material after acid washing to modify the surface of the material after acid washing. In this manufacturing method, the lithium-rich manganese-based positive electrode material is coated with a specific coating before and after acid washing to form a positive electrode active material that satisfies a specific microscopic index range. The specific microscopic index includes at least one of the oxygen vacancy index, microscopic stress, peak intensity ratio MO / Mn-O, and specific surface area, where M is an optional doping element for the lithium-rich manganese-based positive electrode material, thereby providing the positive electrode active material with good storage performance and cycle stability.

[0122] In some embodiments, in the step of coating the lithium-rich manganese-based positive electrode material with the primary coating raw material and sintering it, the sintering temperature is 500°C to 750°C, and optionally the sintering time is 6 hours to 12 hours.

[0123] As an example, the sintering temperature after coating with the primary coating material may be, but is not limited to, any one of 500°C, 550°C, 600°C, 650°C, 700°C, and 750°C, or a range between any two of these.

[0124] As an example, the sintering time after coating with the primary coating material may be, but is not limited to, any one of 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, and 12 hours, or a range between any two of these.

[0125] In these embodiments, after coating with the primary coating material, selecting a relatively high specific sintering temperature helps to properly melt the primary coating material and stably coat it on the surface of the lithium-rich manganese-based positive electrode material, which can better protect the lithium-rich manganese-based positive electrode material during the acid cleaning process. Optionally, selecting an appropriate sintering time is advantageous for achieving both efficiency and sintering effect.

[0126] In some embodiments, the primary coating material comprises one or more of the elements Al, Ce, and Co, and optionally the primary coating material comprises one or more of aluminum fluoride, aluminum oxide, cerium fluoride, and cerium oxide.

[0127] In these embodiments, the primary coating raw material has a specific composition, which can form a dense coating on the surface of the lithium-excess manganese-based positive electrode material after sintering, which can provide good protection for the lithium-excess manganese-based positive electrode material and is advantageous for improving cycle stability.

[0128] In some embodiments, in the step of coating the primary coating pickled material with the secondary coating raw material and sintering, the sintering temperature is 350°C to 550°C, and optionally the sintering time is 6 hours to 12 hours.

[0129] As an example, the sintering temperature after coating with the secondary coating material may be, but is not limited to, any one of 350°C, 400°C, 450°C, 500°C, and 550°C, or a range between any two of these.

[0130] As an example, the sintering time after coating with the secondary coating material may be, but is not limited to, any one of 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, and 12 hours, or a range between any two of these.

[0131] In these embodiments, selecting a relatively low specific sintering temperature after coating with the secondary coating material can effectively melt the secondary coating material, thereby effectively modifying the surface of the lithium-excess manganese-based positive electrode material, and, compared to an excessively high sintering temperature, can also reduce the situation in which the surface defect spinel structure is converted into a rock salt phase, which is advantageous for improving the specific capacity of the positive electrode active material and the initial coulombic efficiency of the battery 100. Optionally, selecting an appropriate sintering time is advantageous for achieving both efficiency and sintering effect.

[0132] In some embodiments, the secondary coating material comprises one or more of the elements Zr, B, and Ti, and optionally the secondary coating material comprises one or more of zirconium oxide, zirconium fluoride, boric acid, and zirconium boride.

[0133] In these embodiments, the secondary coating raw material has a specific composition, which can effectively modify the surface of the lithium-excess manganese-based positive electrode material, which is beneficial to improving cycle stability, and can coat the surface of the lithium-excess manganese-based positive electrode material at a low sintering temperature, which is beneficial to improving the specific capacity of the positive electrode active material and the initial coulombic efficiency of the battery 100.

[0134] In some embodiments, the primary coating raw material comprises one or more of aluminum fluoride, aluminum oxide, cerium fluoride, and cerium oxide, the secondary coating raw material comprises one or more of zirconium oxide, zirconium fluoride, boric acid, and zirconium boride, and the ratio of the total mass of Al and Ce elements in the primary coating raw material to the total mass of Zr and B elements in the secondary coating raw material is 1:(0.5-2).

[0135] For an exemplary selection of the ratio between the total mass of Al and Ce elements in the primary coating raw material and the total mass of Zr and B elements in the secondary coating raw material, see the relevant description of the examples of the first aspect.

[0136] In these embodiments, when the composition ratio of the primary coating material and the secondary coating material meets a specific ratio, the coating layer can more effectively improve the cycle stability of the positive electrode active material.

[0137] In some embodiments, the primary coating raw material includes one or more of Al, Ce, and Co elements, the secondary coating raw material includes one or more of Zr, B, and Ti elements, the primary coating raw material and the secondary coating raw material form a coating layer distributed on at least a portion of the surface of the lithium-rich manganese-based positive electrode material, and in the positive electrode active material, the total content of Al, Ce, Co, Zr, B, and Ti elements in the coating layer is 5000 ppm or less.

[0138] For exemplary selection of the total contents of Al, Ce, Co, Zr, B and Ti elements in the coating layer, refer to the relevant descriptions in the examples of the first aspect.

[0139] In these embodiments, when the content of the element composition of the coating layer in the positive electrode active material is less than a certain range, the coating layer effectively improves the cycle stability of the positive electrode active material, and at the same time, the positive electrode active material has good specific capacity, which is advantageous for improving the initial coulombic efficiency of the battery 100.

[0140] In some embodiments, the primary coating material and the secondary coating material form a coating layer distributed on at least a portion of the surface of the lithium-excess manganese-based positive electrode material, and the thickness of the coating layer is 0.2 μm to 0.8 μm.

[0141] For exemplary selection of the thickness of the coating layer, please refer to the relevant description of the examples of the first aspect.

[0142] In these embodiments, the coating layer has an appropriate thickness, which can effectively exert a protective effect and improve cycle stability, and is advantageous in improving the specific capacity of the positive electrode active material and the initial coulombic efficiency of the battery 100 compared to when the coating layer is too thick.

[0143] In some embodiments, the lithium-rich manganese-based cathode material comprises Li[Li x Ni a Co b Mn c M d ]O 2-e Contains x+a+b+c+d=1, x>0, a>0, 0 <b<0.1、c> 0, d≧0, 0≦e≦0.2, and the M element includes one or more of Mg, Nb, Cr, Ce, Fe, Ta, B, Al, V, Ti, Zr, Sn, and Mo.

[0144] As an example, a lithium-excess manganese-based positive electrode material can be produced by the following method.

[0145] A low-cobalt hydroxide precursor, lithium salt, and zirconium ball mill beads are mixed in a drum-type ball mill grinding mixer at a mass ratio of 25 to 80 parts by mass of beads, and the Li / Me molar ratio is controlled to 1.3 to 1.4, with Me containing nickel, cobalt, manganese, and a modifier element M. The mixture is then sintered in a muffle furnace at a sintering temperature of 780°C to 900°C, a heating rate of 2°C / min to 5°C / min, a sintering time of 10 to 15 hours, and an air atmosphere. After primary sintering, an intermediate product of a lithium-excess manganese-based positive electrode material is obtained, which is then mechanically pulverized and subjected to a vibrating sieve treatment to obtain the lithium-excess manganese-based positive electrode material.

[0146] Optionally, the lithium salts include at least one or more of lithium hydroxide, lithium carbonate, lithium acetate, lithium nitrate, lithium oxalate, and lithium sulfate.

[0147] In these embodiments, the lithium-rich manganese-based positive electrode material has a low cobalt content, which can reduce costs, and the presence of a specific doping element M in the lithium-rich manganese-based positive electrode material is advantageous for improving the specific capacity of the positive electrode active material and the initial coulombic efficiency of the battery 100.

[0148] In some embodiments, in the step of washing the primary coating material with a solution containing an acid and / or an acid salt, the solution containing an acid and / or an acid salt comprises an organic acid and / or an organic acid salt, the pH value of the solution containing the acid and / or the acid salt is 2 to 8, the washing time is 0.25 hours to 4 hours, and optionally, the solution containing the acid and / or the acid salt comprises one or more of citric acid, ammonium citrate, and diammonium hydrogen citrate.

[0149] In this description, acid washing is an abbreviation for the process of washing the primary coating material with a solution containing an acid and / or an acid salt. Note that in the examples of this application, the initial pH value of the solution containing an acid and / or an acid salt may be greater than 7 because the deionized water solvent commonly used for organic acid and / or its salt solution is weakly alkaline.

[0150] By acid salt is meant a salt in which the anion is an acid ion.

[0151] As an example, the pH value of the solution containing the acid and / or acid salt may be, but is not limited to, any one of 2, 3, 4, 5, 6, 7, and 8, or a range between any two of these values.

[0152] Optionally, the acids and / or acid salts included include one or more of citric acid, ammonium citrate and diammonium hydrogen citrate.

[0153] By way of example, the wash time value may be, but is not limited to, any one of the following values ​​or a range between any two of: 0.25 hours, 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, and 4 hours.

[0154] The washing process may be accompanied by a stirring operation, and the stirring speed is selectively 800 rpm to 1200 rpm, for example, 800 rpm, 900 rpm, 1000 rpm, 1100 rpm, 1200 rpm, etc., but is not limited to these.

[0155] In these examples, the specific capacity of the positive electrode active material and the initial coulombic efficiency of the battery 100 can be improved by performing acid washing under specific pH value and washing time conditions.

[0156] According to a third aspect, an embodiment of the present application provides a positive electrode sheet including the positive electrode active material of the above embodiment or the positive electrode active material obtained by the method for producing the positive electrode active material of the above embodiment.

[0157] According to a fourth aspect, an embodiment of the present application provides a battery including the positive electrode sheet of the above embodiment.

[0158] According to a fifth aspect, an embodiment of the present application provides a power consuming device including the battery of the above embodiment.

[0159] The present invention will be further described below with reference to some specific examples.

[0160] 1. Battery cell manufacturing (1) Manufacturing of cathode materials Step S1: A low-cobalt hydroxide precursor, lithium salt, and ball mill zirconium beads were mixed in a drum-type ball mill grinding mixer at a mass ratio of 60:1, and the Li / Me molar ratio was controlled to 1.35. Me contains nickel, cobalt, manganese, and a modifier element M. The mixture was then sintered in a muffle furnace. The sintering temperature was 800°C, the heating rate was 2°C / min, the sintering time was 10 hours, and the sintering atmosphere was air. After the primary sintering, an intermediate product of a lithium-excess manganese-based positive electrode material was obtained. The intermediate product was then mechanically pulverized and subjected to a vibrating sieve treatment to obtain a lithium-excess manganese-based positive electrode material.

[0161] The chemical formula of the obtained lithium-excess manganese-based cathode material is Li 1.15 Ni 0.25 Co 0.05 Ti 0.02 Mn 0.53 The measured value was O2, Dv50 was 6.5 μm, and SPAN was 1.15. SPAN indicates the span, and SPAN = (Dv90 - Dv10) / Dv50.

[0162] Step S2: The lithium-rich manganese-based positive electrode material and a certain amount of primary coating raw material were placed in a drum-type ball mill grinder / mixer and mixed for 10 hours, then placed in a muffle furnace for sintering. The heating rate was 2-5°C / min, the sintering temperature and sintering time were as shown in Table 1, and the sintering atmosphere was air. The sintered material was mechanically crushed and subjected to a vibrating sieve treatment to obtain the primary coating material.

[0163] Step S3: Citric acid was dissolved in deionized water to prepare a citric acid solution. The concentration of citric acid in the solution was 3 g / L, and the pH of the solution was 2.57. The primary coating material from step S1 was then weighed and washed in the citric acid solution at a solid-liquid ratio of 25:1. The washing time was 0.5 hours, and the stirring speed was 900 rpm. After washing, the material was filtered with suction, washed with deionized water, filtered with suction, dried at 80°C for 10 hours, mechanically crushed, and sieved to obtain the primary coating acid-washed material.

[0164] Step S4: The primary coating acid-washed material obtained in Step S3 and a certain amount of secondary coating raw material were placed in a drum ball mill grinder / mixer and mixed for 10 hours, then placed in a muffle furnace for sintering. The heating rate was 2°C / min, the sintering temperature and sintering time were as shown in Table 1, and the sintering atmosphere was air. The sintered material was mechanically crushed and subjected to a vibrating sieve treatment to obtain the positive electrode active material.

[0165] (2) Manufacturing of positive electrode sheets The positive electrode active material prepared above was placed in a 5L stirring tank and premixed for 30 minutes. Then, the conductive agent carbon black (SP) and the binder polyvinylidene fluoride (PVDF) were added, followed by secondary drying and mixing for 30 minutes. The mass ratio of the positive electrode active material, conductive agent, and binder was 96:2:2. The solvent N-methylpyrrolidone (NMP) was added, and the mixture was rapidly stirred under vacuum conditions to form a positive electrode paste with a solid content of 70 wt%. The positive electrode paste was uniformly applied to both sides of a 12 μm-thick aluminum foil, and the coated polar sheet was dried in an oven at 100°C to 130°C for 30 minutes before being removed to obtain a positive electrode sheet. The positive electrode active material loading on the positive electrode sheet was 21.5 mg / cm. 2 It was.

[0166] (3) Manufacturing of negative electrode sheets The negative electrode active materials, artificial graphite and hard carbon, the conductive agent acetylene black, the binder styrene butadiene rubber (SBR), and the thickener sodium carboxymethyl cellulose (CMC) were prepared in a mass ratio of 90:5:2:2:1 and thoroughly mixed in a deionized water solvent system to obtain a negative electrode paste. The negative electrode paste was applied to copper foil, dried, and cold-pressed to obtain a negative electrode sheet.

[0167] (4) Battery assembly The positive electrode sheet, separator, and negative electrode sheet were stacked in this order using a polyethylene porous polymer film as a separator. Here, the separator serves to isolate the positive and negative electrode sheets. After winding, the sheet was placed in a housing and a blended base electrolyte was injected to obtain a battery cell. The base electrolyte was 1 mol / L LiPF6 / (EC+EMC+DMC), and the volume ratio of EC, EMC, and DMC in the solvent was 1:1:1.

[0168] As will be understood by those skilled in the art, in the above methods of the specific examples and comparative examples, the order of the steps described does not limit the configuration of the implementation process by a strict execution order, and the specific execution order of each step should be determined according to its function and possible internal logic.

[0169] II. Test Method (1) Specific capacity and initial coulombic efficiency test The button battery was tested by charging it from 2.5V to 4.55V at a 0.1C rate up to 4.55V, then charging it at a constant voltage of 4.55V until the current fell to 0.05mA or less, and letting it stand for 2 minutes. The charge capacity at this point was taken as C0. It was then discharged at a 0.1C rate down to 2.5V, and the discharge capacity at this point was taken as the specific capacity, D0. The initial coulombic efficiency was D0 / C0 * 100%.

[0170] (2) Oxygen deficiency index test X-ray diffraction spectrum test conditions: Refer to JIS K 0131-1996, general rules for XRD tests, and include the following requirements: (1) Dry the sample. (2) The sample particle size must be less than 10 μm. If the sample is scraped from a polar sheet or is a lump sample, it must be crushed and sieved through a 200 mesh.

[0171] JPEG2026500730000003.jpg27165

[0172] (3) Microscopic stress testing X-ray diffraction spectrum testing was performed under the following conditions. The general rules for XRD testing, JIS K 0131-1996, were referenced, and the following requirements were included: (1) The sample was dried. (2) The sample particle size was less than 10 μm. If the sample was scraped from a polar sheet or was a lump sample, it was necessary to crush it and sieve it through a 200-mesh screen.

[0173] Microscopic stress of the positive electrode active material = (β hkl *cosθ hkl ) / (4sinθ hkl ) where θ hkl is the diffraction angle of the (hkl) crystal plane diffraction peak of the lithium-rich manganese-based positive electrode material in the XRD diffraction pattern, and β hkl is the full width at half maximum of the (hkl) crystal plane diffraction peak of the lithium-excess manganese-based positive electrode material in the XRD diffraction pattern.

[0174] (4) Peak intensity ratio MO / Mn-O test Specifically, the national standard GB / T 6040-2002 was referenced.

[0175] The method for confirming the peak intensity MO is as follows: The M element is Ti, and the peak intensity MO is 900 cm in the Fourier infrared spectrum. -1 ~1000cm -1 is the diffraction peak intensity at the point.

[0176] The method for confirming the Mn-O peak intensity is as follows: 600 cm of the Fourier infrared spectrum -1 ~620cm -1 is the diffraction peak intensity at the point.

[0177] (5) Specific surface area test Specifically, the national standard GB / T 19587-2004 was referenced.

[0178] 1) Pretreatment: An appropriate amount of sample was placed in a dedicated sample tube, heated, and evacuated for 2 hours. After cooling to room temperature, the total weight was measured and the mass of the sample tube was subtracted to obtain the sample mass.

[0179] 2) Test: The sample tube was placed in the workstation and the amount of gas adsorbed on the solid surface was measured at a constant temperature under different adsorption pressures. The monolayer adsorption amount of the sample was calculated based on the BET multilayer adsorption theory and its formula, and the specific surface area of ​​the solid sample per unit mass was then calculated.

[0180] 3) Adsorption gas: nitrogen, adsorption pressure points: 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, test atmosphere: high-purity liquid nitrogen atmosphere.

[0181] (6) Cycle characteristic test All batteries were tested in a constant temperature environment of 25°C. The batteries were charged at a 1C rate from 2.5V to 4.45V up to 4.45V. They were then charged at a constant voltage of 4.45V until the current reached 0.05mA or less, and allowed to stand for 5 minutes. They were then discharged at a 1C rate to 2.5V, and the discharge capacity was recorded. This process was repeated to obtain the capacity retention rate after a specified number of cycles. Capacity retention rate = discharge capacity at the first cycle / discharge capacity at the specified number of cycles × 100%.

[0182] 3. Experimental conditions and test results The main experimental conditions for the manufacturing methods corresponding to each experimental group are shown in Table 1, the parameters of the obtained positive electrode active materials are shown in Table 2, and the test results of the battery performance after applying the positive electrode active materials to the battery are shown in Table 3.

[0183] [Table 1-1] [Table 1-2]

[0184] In Table 1, Examples 31 and 32 indicate that the sample was not coated with the primary coating material, Examples 33 and 34 indicate that the sample was not coated with the secondary coating material, and Comparative Example 1 indicates that the sample was not coated with either the primary coating material or the secondary coating material.

[0185] [Table 2]

[0186] [Table 3]

[0187] Combining Tables 1 to 3, a brief analysis is as follows:

[0188] In the examples, the lithium-excess manganese-based positive electrode material was coated with specific primary coating materials and secondary coating materials and sintered before and after acid washing, respectively, while no coating was performed in Comparative Example 1. The resulting positive electrode active material was applied to a battery in the examples, which had a higher cycle capacity retention rate than Comparative Example 1.

[0189] In Examples 1 to 5, the sintering temperature after coating the primary coating raw material was different, and as the sintering temperature gradually increased within the range of 500°C to 800°C, the cycle capacity retention rate first increased and then decreased. When the sintering temperature was 500°C to 750°C, a relatively high cycle capacity retention rate was obtained.

[0190] In Examples 1 and 6 to 9, the sintering time after coating the primary coating material was different. As the sintering time gradually increased within the range of 6 to 15 hours, the cycle capacity retention rate first increased and then decreased. When the sintering time was 6 to 12 hours, a relatively high cycle capacity retention rate was obtained.

[0191] In Examples 1 and 10 to 13, the sintering temperature after coating the secondary coating material was different. As the sintering temperature gradually increased within the range of 350°C to 600°C, the cycle capacity retention first increased and then decreased. When the sintering temperature was 350°C to 550°C (e.g., 350°C to 450°C), the cycle capacity retention was relatively high, and the specific capacity and initial coulombic efficiency were also high.

[0192] In Examples 1 and 14 to 17, the sintering time after coating the secondary coating material was different. As the sintering time gradually increased within the range of 6 to 15 hours, the cycle capacity retention first increased and then decreased. When the sintering time was 6 to 12 hours, a relatively high cycle capacity retention was obtained.

[0193] In Example 1 and Examples 18 to 20, the types of primary coating raw materials are different, and all of the positive electrode active materials have a relatively high cycle capacity retention rate.

[0194] In Example 1 and Examples 21 to 23, the types of secondary coating raw materials are different, and all of the positive electrode active materials have a relatively high cycle capacity retention rate.

[0195] In Examples 1 and 24 to 26, the total amount of Al, Ce, Zr, and B in the positive electrode active material and the thickness of the coating layer varied. Increasing the coating layer thickness within a certain range was beneficial for improving cycle performance. Compared to excessive thickness, an appropriate coating thickness favors uniform coating, reduces localized transition metal elution, and reduces capacity fade and polarization. When the total amount of the specified elements in the coating layer was 2000 ppm to 6000 ppm and the coating layer thickness was 0.3 μm to 0.8 μm, the specific capacity, initial coulombic efficiency, and cycle capacity retention initially increased and then decreased. When the total amount of the specified elements in the coating layer was 2000 ppm to 5000 ppm, relatively high specific capacity, initial coulombic efficiency, and cycle capacity retention were achieved.

[0196] In Example 1 and Examples 27 to 30, the ratio of the total mass of Al and Ce elements in the primary coating raw material to the total mass of Zr and B elements in the secondary coating raw material is slightly different, and when the ratio of the two is within the range of 1:(0.5 to 2), a relatively high cycle capacity retention rate is achieved.

[0197] In Example 1 and Examples 31 to 34, Examples 31 and 32 indicate that the batteries are not coated with the primary coating material, and Examples 33 and 34 indicate that the batteries are not coated with the secondary coating material. Example 1 clearly has a higher cycle capacity retention rate.

[0198] Finally, it should be noted that the above embodiments are merely for illustrating the technical solutions of the present application, and are not intended to limit the same. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may still be modified, or some or all of the technical features therein may be equivalently substituted, and such modifications or substitutions do not cause the substance of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application, and all of them should be encompassed by the claims and the description of the present application. In particular, the technical features mentioned in the embodiments may be combined in any way as long as there is no structural contradiction. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions encompassed by the claims.

Claims

1. A positive electrode active material comprising a lithium-rich manganese-based positive electrode material and a coating layer distributed on at least a portion of the surface of the lithium-rich manganese-based positive electrode material, the lithium-rich manganese-based positive electrode material includes an M element, the M element including one or more of Mg, Nb, Cr, Ce, Fe, Ta, B, Al, V, Ti, Zr, Sn, and Mo; the coating layer includes at least one of a metal oxide and a metal fluoride; The specific capacity of the positive electrode active material is 220 mAh / g or more, A positive electrode active material that satisfies at least one of the following conditions (a1) to (d1): (a1) In a refinement result of an X-ray diffraction spectrum of the positive electrode active material, the oxygen vacancy index is 2.12 or more. (b1) The microscopic stress of the positive electrode active material is 0.1% to 1.5%. (c1) In the Fourier infrared spectrum of the positive electrode active material, the peak intensity ratio MO / Mn—O is 25 to 40. (d1) The specific surface area of ​​the positive electrode active material is 0.9 m ２ / g to 3.5m ２ / g.

2. The positive electrode active material according to claim 1, which satisfies at least one of the following conditions (a2) to (d2): (a2) In a refinement result of an X-ray diffraction spectrum of the positive electrode active material, the oxygen deficiency index is 2.72 or more. (b2) The microscopic stress of the positive electrode active material is 0.1% to 0.8%. (c2) In the Fourier infrared spectrum of the positive electrode active material, the peak intensity ratio MO / Mn—O is 30 to 40. (d2) The specific surface area of ​​the positive electrode active material is 1.5 m ２ / g to 2.5m ２ / g.

3. 3. The positive electrode active material according to claim 1, wherein the coating layer has an elemental composition including one or more of an Al element, a Ce element, and a Co element, and one or more of a Zr element, a B element, and a Ti element.

4. 4. The positive electrode active material according to claim 3, wherein in the coating layer, a ratio of the total mass of the Al element and the Ce element to the total mass of the Zr element and the B element is 1:(0.5 to 2).

5. 5. The cathode active material according to claim 3, wherein the total content of the Al element, the Ce element, the Co element, the Zr element, the B element, and the Ti element in the coating layer is 5000 ppm or less.

6. 6. The positive electrode active material of claim 1, wherein the coating layer comprises one or more of aluminum fluoride, aluminum oxide, cerium fluoride, and cerium oxide, and one or more of zirconium oxide, zirconium fluoride, boric acid, and zirconium boride.

7. The positive electrode active material according to any one of claims 1 to 6, wherein the ratio of the volume-based particle size distribution Dv50 of the lithium-excess manganese-based positive electrode material to the thickness of the coating layer is (5.5 to 6.5):(0.2 to 0.8).

8. The cathode active material according to any one of claims 1 to 7, wherein the coating layer has a thickness of 0.2 µm to 0.8 µm.

9. The lithium-excess manganese-based positive electrode material is Li[Li ｘ Ni ａ Co ｂ Mn ｃ M ｄ ]O ２－ｅ wherein x+a+b+c+d=1, x>0, a>0, 0<b<0.1, c>0, d≧0, 0≦e≦0.

2. The positive electrode active material according to any one of claims 1 to 8.

10. Coating the lithium-rich manganese-based positive electrode material with a primary coating raw material and sintering it to obtain a primary coating material; washing the primary coating material with a solution containing an acid and / or an acid salt to obtain a primary coating acid-washed material; and coating the primary coating pickled material with a secondary coating raw material and sintering the coated material to obtain a positive electrode active material, the primary coating material comprises one or more of a metal oxide and a metal fluoride, and the secondary coating material comprises one or more of a metal oxide, a metal fluoride, and a boride.

11. 11. The method according to claim 10, wherein in the step of coating the lithium-excess manganese-based positive electrode material with the primary coating raw material and sintering, the sintering temperature is 500°C to 750°C, and optionally the sintering time is 6 hours to 12 hours.

12. 12. The manufacturing method according to claim 10 or 11, wherein the primary coating raw material comprises one or more of Al, Ce and Co elements, and optionally the primary coating raw material comprises one or more of aluminum fluoride, aluminum oxide, cerium fluoride and cerium oxide.

13. The manufacturing method according to any one of claims 10 to 12, wherein in the step of coating the primary-coating pickling material with the secondary-coating raw material and sintering, the sintering temperature is 350°C to 550°C, and optionally the sintering time is 6 hours to 12 hours.

14. The manufacturing method according to any one of claims 10 to 13, wherein the secondary coating raw material comprises one or more of Zr element, B element and Ti element, and optionally the secondary coating raw material comprises one or more of zirconium oxide, zirconium fluoride, boric acid and zirconium boride.

15. 15. The method according to claim 10, wherein the primary coating raw material comprises one or more of aluminum fluoride, aluminum oxide, cerium fluoride, and cerium oxide, the secondary coating raw material comprises one or more of zirconium oxide, zirconium fluoride, boric acid, and zirconium boride, and a ratio of a total mass of Al and Ce elements in the primary coating raw material to a total mass of Zr and B elements in the secondary coating raw material is 1:(0.5-2).

16. 16. The method according to claim 10, wherein the primary coating raw material contains one or more of an Al element, a Ce element, and a Co element, the secondary coating raw material contains one or more of a Zr element, a B element, and a Ti element, the primary coating raw material and the secondary coating raw material form a coating layer that is distributed on at least a part of the surface of the lithium-excess manganese-based positive electrode material, and in the positive electrode active material, a total content of the Al element, the Ce element, the Co element, the Zr element, the B element, and the Ti element in the coating layer is 5000 ppm or less.

17. 17. The manufacturing method according to claim 10, wherein the primary coating raw material and the secondary coating raw material form a coating layer distributed on at least a part of the surface of the lithium-excess manganese-based positive electrode material, and the thickness of the coating layer is 0.2 μm to 0.8 μm.

18. The lithium-excess manganese-based positive electrode material is Li[Li ｘ Ni ａ Co ｂ Mn ｃ M ｄ ]O ２－ｅ wherein x+a+b+c+d=1, x>0, a>0, 0<b<0.1, c>0, d≧0, 0≦e≦0.2, and the M element comprises one or more of Mg, Nb, Cr, Ce, Fe, Ta, B, Al, V, Ti, Zr, Sn, and Mo.

19. 19. The method according to any one of claims 10 to 18, wherein in the step of washing the primary coating material with a solution containing an acid and / or an acid salt, the solution containing an acid and / or an acid salt comprises an organic acid and / or an organic acid salt, the pH value of the solution containing an acid and / or an acid salt is 2 to 8, and the washing time is 0.25 hours to 4 hours, and optionally the solution containing an acid and / or an acid salt comprises one or more of citric acid, ammonium citrate, and diammonium hydrogen citrate.

20. A positive electrode sheet comprising the positive electrode active material according to any one of claims 1 to 9 or the positive electrode active material obtained by the method for producing a positive electrode active material according to any one of claims 10 to 19.

21. A battery comprising the positive electrode sheet of claim 20.

22. 22. A power consuming device comprising the battery of claim 21.

Images