Positive electrode active material precursor, positive electrode active material, manufacturing method, and secondary battery

Abstract

The present application provides a cathode active material precursor, a cathode active material, a manufacturing method, and a secondary battery, the manufacturing method including the steps of: preparing a metal salt aqueous solution and a precipitant aqueous solution, the precipitant comprising one or more selected from oxalic acid and a water-soluble oxalate; mixing the precipitant aqueous solution and the metal salt aqueous solution at a shear rate of 10,000 r / min or more, and then carrying out a co-precipitation reaction; and washing and drying the mixture after the reaction to obtain the cathode active material precursor. The manufacturing method according to the present application can obtain a cathode active material precursor with regular morphology, small particle size, narrow particle size distribution, single crystal phase, high purity, uniform element distribution, and high batch stability and consistency, thereby improving the electrochemical performance of the cathode active material and the secondary battery.

Description

[Technical Field]

[0001] This application belongs to the field of battery technology and specifically relates to a positive electrode active material precursor, a positive electrode active material, a manufacturing method, and a secondary battery. [Background technology]

[0002] In recent years, secondary batteries have been widely used in many fields, including energy storage and power systems such as hydroelectric, thermal, wind, and solar power plants, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace. The positive electrode active material is one of the important elements that affect the electrochemical performance of secondary batteries, and commonly used oxalate precursors, for example, are one of the important elements that affect the performance of the positive electrode active material. However, currently manufactured oxalate precursors have defects such as irregular morphology, large particle size, wide particle size distribution, and poor batch stability and consistency, which affect the electrochemical performance of the positive electrode active material and secondary batteries. [Overview of the project]

[0003] The object of this application is to provide a positive electrode active material precursor, a positive electrode active material, a manufacturing method, and a secondary battery that can improve the electrochemical performance of the positive electrode active material and the secondary battery by obtaining a positive electrode active material precursor that is well-formed, has a small particle size, a narrow particle size distribution, a single crystalline phase, high purity, a uniform elemental distribution, and high batch stability and consistency.

[0004] A first aspect of this application provides a method for producing a positive electrode active material precursor, comprising: step S1, preparing an aqueous metal salt solution and an aqueous precipitant solution, wherein the precipitant solution includes one or more selected from oxalic acid and water-soluble oxalates; step S2, mixing the aqueous precipitant solution and the aqueous metal salt solution at a shear rate of 10,000 r / min or more, and then carrying out a coprecipitation reaction; and step S3, washing and drying after the reaction is completed to obtain the positive electrode active material precursor.

[0005] In the process of research, the inventors of the present application found that by mixing an aqueous solution of a precipitant and an aqueous solution of a metal salt at a shear rate of 10,000 r / min or more using a high-speed homogenizer and then performing a coprecipitation reaction, not only can the production efficiency of the cathode active material precursor be further improved, but also a cathode active material precursor with a regular shape, small particle size, narrow particle size distribution, single crystal phase, high purity, uniform element distribution, and high batch stability and consistency can be obtained. The manufacturing method according to the present application has the advantages of simple process, high production efficiency, and being easy to perform large-scale production in industrialization. The manufacturing method according to the present application can also achieve low-cost and environmentally friendly production and has high industrialization value. The manufacturing method according to the present application also contributes to accurately controlling the particle size of the cathode active material precursor.

[0006] In any embodiment of the present application, in S2, the coprecipitation reaction is carried out in a high-speed homogenizer. <(

[0007] In any embodiment of the present application, in S2, the shear rate is 10,000 r / min - 28,000 r / min. By controlling the magnitude of the shear rate, it also contributes to obtaining cathode active material precursors with different particle sizes. Therefore, the manufacturing method according to the present application also contributes to accurately controlling the particle size of the cathode active material precursor.

[0008] In any embodiment of the present application, in S2, the time of the coprecipitation reaction is 10 min - 60 min.

[0009] In any embodiment of the present application, in S2, the temperature of the coprecipitation reaction is 20°C - 80°C.

[0010] In any embodiment of the present application, in S2, the molar ratio of the usage amounts of the precipitant and the metal salt is 1:1 - 3:1. By adjusting the usage amount of the precipitant, it also contributes to improving the conversion efficiency of metal ions and making the coprecipitation reaction more complete.

[0011] In any embodiment of this application, in S1, the concentration of the metal salt aqueous solution is 0.5 mol / L to 2 mol / L.

[0012] In any embodiment of this application, in S1, the concentration of the aqueous solution of the precipitating agent is 0.5 mol / L to 2 mol / L.

[0013] In any embodiment of this application, the aqueous metal salt solution is prepared by dissolving a metal salt in water to form an aqueous metal salt solution under a protective gas atmosphere containing nitrogen gas, an inert gas, or a combination thereof.

[0014] In any embodiment of this application, in S1, the metal salt comprises one or more selected from metal sulfates, nitrates, hydrochlorides, and acetates.

[0015] In any embodiment of this application, in S1, the water-soluble oxalate comprises one or more selected from lithium oxalate, sodium oxalate, potassium oxalate, and ammonium oxalate.

[0016] In any embodiment of this application, in S1, the metal salt is a divalent metal salt.

[0017] In any embodiment of this application, the metal salt includes one or more selected from divalent Mn salts, Fe salts, Ni salts, Co salts, Mg salts, Zn salts, Ca salts, Ti salts, V salts, and Cr salts.

[0018] In any embodiment of this application, the metal salt comprises at least a divalent Mn salt.

[0019] In any embodiment of this application, the metal salt comprises a divalent Mn salt, an Fe salt, and a salt of another selectable metal M1, where M1 represents doping elements for manganese and iron sites, and optionally, the salt of the other metal M1 comprises one or more selected from divalent Ni salts, Co salts, Mg salts, Zn salts, Ca salts, Ti salts, V salts, and Cr salts, thereby enabling the production of a precursor for lithium manganese iron phosphate cathode active material.

[0020] In any embodiment of this application, the metal salt comprises a divalent Mn salt, Ni salt, Co salt, and a salt of another selectable metal M2, where M2 represents a doping element of manganese site, nickel site, and cobalt site, and optionally, the salt of the other metal M2 comprises one or more selected from divalent Fe salt, Mg salt, Zn salt, Ca salt, Ti salt, V salt, and Cr salt, thereby enabling the production of a precursor for lithium nickel-cobalt-manganate cathode active material.

[0021] In any embodiment of this application, the metal salt comprises a divalent Mn salt, a Ni salt, and a salt of another selectable metal M3, where M3 represents doping elements for manganese and nickel sites, and optionally, the salt of the other metal M3 comprises one or more selected from divalent Fe salts, Co salts, Mg salts, Zn salts, Ca salts, Ti salts, V salts, and Cr salts, thereby enabling the production of a precursor for lithium-rich manganese cathode active material.

[0022] In any embodiment of this application, the metal salt aqueous solution further comprises a complexing agent. By adding a complexing agent to the metal salt aqueous solution, the purity of the obtained positive electrode active material precursor is improved, the impurity content is reduced, the difference between the proportion of each metal ion in the obtained positive electrode active material precursor particles and the proportion of each metal ion in the raw materials is reduced, and the composition of the positive electrode active material precursor can be precisely controlled.

[0023] In any embodiment of the present application, the complexing agent includes one or more selected from aminocarboxylates, hydroxycarboxylates, and organic phosphonates. Optionally, the complexing agent includes one or more selected from ethylenediaminetetraacetates, gluconates, citrates, tartrates, metasilicates, tripolyphosphates, nitrilotriacetates, diethylenetriaminepentamethylenephosphonates, ethylenediaminetetrakis(methylenephosphonates), and hydroxyethanediphosphonates.

[0024] In any embodiment of the present application, the content of the complexing agent is 10 wt% or less (≦10 wt%) with respect to the total mass of the aqueous metal salt solution.

[0025] A second aspect of the present application has a molecular formula of Fe x Mn y M1 1-x-y C2O4, Ni a Co b Mn c M2 1-a-b-c C2O4 or Ni p Mn q M3 1-p-q C2O4, where 0 < x < 1, 0 < y < 1, 0 ≦ 1 - x - y < 1, M1 represents a doping element for a manganese site and an iron site, and optionally includes one or more selected from Ni, Co, Mg, Zn, Ca, Ti, V, and Cr, 0 < a < 1, 0 < b < 1, 0 < c < 1, 0 ≦ 1 - a - b - c < 1, M2 represents a doping element for a manganese site, a nickel site, and a cobalt site, and optionally includes one or more selected from Fe, Mg, Zn, Ca, Ti, V, and Cr, 0 < p < 1, 0 < q < 1, 0 ≦ 1 - p - q < 1, M3 represents a doping element for a manganese site and a nickel site, and optionally includes one or more selected from Fe, Co, Mg, Zn, Ca, Ti, V, and Cr, and provides a cathode active material precursor produced by the method according to the first aspect of the present application.

[0026] In any embodiment of the present application, the volume particle size Dv50 of the cathode active material precursor satisfies 0.3 μm ≦ Dv50 ≦ 3 μm.

[0027] In any embodiment of the present application, the volume particle sizes Dv90 and Dv50 of the cathode active material precursor satisfy 1 < Dv90 / Dv50 ≤ 1.5.

[0028] A third aspect of the present application provides a method for manufacturing a cathode active material, including the step of mixing a cathode active material precursor manufactured by the method described in the first aspect of the present application or the cathode active material precursor of the second aspect of the present application with a lithium source and / or a phosphorus source at a predetermined ratio, and then performing a sintering process to obtain the cathode active material.

[0029] A fourth aspect of the present application provides a cathode active material manufactured by the method described in the third aspect of the present application.

[0030] A fifth aspect of the present application provides a secondary battery including the cathode active material manufactured by the method described in the third aspect of the present application or the cathode active material of the fourth aspect of the present application.

[0031] The cathode active material precursor according to the present application has the characteristics of regular morphology, small particle size, narrow particle size distribution, single crystal phase, high purity, uniform element distribution, and high batch stability and consistency. Therefore, the electrochemical performance of the cathode active material and the secondary battery can be improved.

Brief Description of Drawings

[0032] <了 [Figure 1] It is a scanning electron microscope (SEM) image of the cathode active material precursor manufactured in Example 3. The magnification of FIG. 1(a) is 1000 times, and the magnification of FIG. 1(b) is 5000 times. [Figure 2] It is a scanning electron microscope (SEM) image of the cathode active material precursor manufactured in Comparative Example 2. The magnification of FIG. 2(a) is 2000 times, and the magnification of FIG. 2(b) is 5000 times. [Figure 3] It is a graph of the first charge-discharge curves of coin cells manufactured in Example 1, Example 2, and Comparative Example 1. Embodiments for Carrying Out the Invention

[0033] The following describes in detail embodiments specifically disclosing the positive electrode active material precursor, positive electrode active material, manufacturing method, and secondary battery of this application, with appropriate reference to the drawings. However, unnecessary details may be omitted. For example, detailed explanations of already well-known matters or redundant explanations of substantially identical configurations may be omitted. This is to avoid the following description becoming unnecessarily verbose and to facilitate understanding for those skilled in the art. The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter described in the claims.

[0034] The “range” disclosed in this application is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting one lower limit and one upper limit, the selected lower limit and upper limit limit the boundary of a special range. The range thus limited may be an endpoint or a range that does not include endpoints, or may be any combination thereof, that is, any lower limit may be combined with any upper limit. For example, if the ranges 60-120 and 80-110 are given for a particular parameter, the ranges 60-110 and 80-120 can also be expected. Also, if the minimum range values ​​1 and 2 and the maximum range values ​​3, 4 and 5 are given, the ranges 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5 can all be expected. In this application, unless otherwise stated, the numerical range “ab” is an abbreviation for any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" in this specification indicates that all real numbers between "0-5" are listed, and "0-5" is an abbreviation for combinations of these numbers. Also, when a parameter is described as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0035] Unless otherwise specified, all embodiments and optional embodiments of this application may be combined to form new technical concepts. Such technical concepts should be considered to be included in the disclosures of this application.

[0036] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical concepts. Such technical concepts should be considered to be included in the disclosures of this application.

[0037] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, but it is preferable that they be performed sequentially. For example, if the method includes steps S1 and S2, it means that the method may include steps S1 and S2 performed sequentially, or steps S2 and S1 performed sequentially. For example, if it is mentioned that the method may further include step S3, it means that step S3 may be added to the method in any order. For example, the method may include steps S1, S2 and S3, or steps S1, S3 and S2, or steps S3, S1 and S2, and so on.

[0038] Unless otherwise specified, the terms "contains," "possesses," and "equip" as used in this application mean open-ended, or they may also mean closed-ended. For example, the terms "contains," "possesses," and "equip" can mean further "contains," "possesses," or "equips" other components not listed, or "contains," "possesses," or "equips" only the listed components.

[0039] Unless otherwise specified, the term "or" in this application is inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, any of the following conditions are met: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0040] In this application, the terms "multiple" and "multiple types" refer to two or more.

[0041] Coprecipitation is a common manufacturing process for producing cathode active material precursors. However, during the coprecipitation process, the growth rate of crystal nuclei is rapid, making it difficult to control the size and morphology of the resulting crystals. Consequently, the resulting cathode active material precursors typically have defects such as large particle size (for example, volume particle size Dv50 is usually 10 μm-40 μm), a wide particle size distribution, irregular morphology, and poor batch stability and consistency. Furthermore, when subsequently producing the cathode active material, it is necessary to perform ball milling for a long time to reduce the particle size, which is a time-consuming and energy-intensive process. In addition, achieving uniformity of the mixed materials when producing the cathode active material is difficult, affecting the electrochemical performance of both the cathode active material and the secondary battery.

[0042] The inventors of this application, in the course of their research, unexpectedly discovered that by mixing and reacting an aqueous precipitate solution with an aqueous metal salt solution at a shear rate of 10,000 r / min or more, it is possible to obtain a cathode active material precursor that is morphologically uniform, has a small particle size, a narrow particle size distribution, a single crystalline phase, high purity, a uniform elemental distribution, and high batch stability and consistency, thereby improving the electrochemical performance of cathode active materials and secondary batteries.

[0043] Specifically, a first embodiment of the present application provides a method for producing a positive electrode active material precursor, comprising: step S1, preparing a metal salt aqueous solution and a precipitating agent aqueous solution, wherein the precipitating agent includes one or more types selected from oxalic acid and water-soluble oxalates; step S2, mixing the precipitating agent aqueous solution and the metal salt aqueous solution at a shear rate of 10,000 r / min or more, and then carrying out a coprecipitation reaction; and step S3, washing and drying after the reaction is completed to obtain the positive electrode active material precursor.

[0044] In S2, the coprecipitation reaction is carried out using a high-speed homogenizer.

[0045] Currently, in conventional techniques, when producing cathode active material precursors by coprecipitation, the stirring reaction is carried out in a regular stirrer at a stirring speed of 1200 r / min or less. Furthermore, previous research has concluded that once the stirring speed reaches a certain value, it is not possible to have a favorable effect on crystal growth, for example, it is not possible to further refine the particle size. However, the inventors of this application have discovered, in the course of their research, that by mixing the precipitate aqueous solution and the metal salt aqueous solution at a shear rate of 10,000 r / min or more using a high-speed homogenizer and then carrying out the coprecipitation reaction, it is possible to not only further improve the production efficiency of cathode active material precursors, but also to obtain cathode active material precursors that are morphologically uniform, have small particle size, a narrow particle size distribution, a single crystalline phase, high purity, a uniform elemental distribution, and high batch stability and consistency.

[0046] High-speed homogenizers have a unique stator and rotor structure that generates extremely strong shearing force, rapidly reducing the size of materials, making them finer, improving the degree of dispersion, and allowing for circulating material processing, completing dispersion, emulsification, homogenization, and mixing steps online. Conventional stirrers, even at high stirring speeds, can only exert a simple dispersion action to sufficiently dissolve each reaction material in the solvent, but they cannot exert shearing and fine-grinding actions.

[0047] In the manufacturing method of this invention, the shearing action of the high-speed homogenizer instantaneously increases the initial concentration of the reaction system, allowing the metal salt and the precipitant to directly co-precipitate. Therefore, the manufacturing method of this invention further increases the rate of crystal nucleation, allowing crystal particles to rapidly generate nuclei and grow slowly, thereby achieving the effect of effectively controlling the particle size and particle size distribution of the positive electrode active material precursor.

[0048] In the coprecipitation reaction process, the reaction material is drawn into the working chamber using the high-speed rotation of a high-speed homogenizer. The reaction material is then dispersed radially into the reasonably narrow gap between the rotor and stator by the strong centrifugal force of the homogenizer. The cathode active material precursor particles generated at this time are thoroughly dispersed and crushed by the combined effects of strong liquid phase shear, liquid phase friction, and tearing impact, and can be ejected at high speed through the stator groove. Subsequently, the flow direction is changed by the resistance force between the reaction material itself and the container wall, and at the same time, the action of the suction force in the vertical axis direction generated in the rotor region creates two strong inverted turbulent flows, greatly enhancing the mass transfer process. Therefore, after multiple cycles, cathode active material precursor particles with a uniform shape, small particle size, narrow particle size distribution, single crystalline phase, high purity, uniform elemental distribution, and high batch stability and consistency can be obtained. Furthermore, the cathode active material produced therefrom can have good batch stability and consistency and excellent electrochemical performance.

[0049] Furthermore, in a solid-phase ball mill process that uses the cathode active material precursor obtained by the manufacturing method of this application as a raw material to produce a subsequent cathode active material, uniform mixing of multiple elements can be easily achieved. This can also significantly reduce the energy consumption and time of the ball mill process.

[0050] The manufacturing method described in this application has the advantages of being simple in process, highly efficient in production, and easy to implement on a large scale for industrialization.

[0051] The manufacturing method described in this application uses water (for example, pure water, distilled water, or deionized water) as a solvent, has high precipitation and conversion efficiency of metal ions, and does not require the addition of organic solvents (for example, alcohols or esters), thereby reducing process costs and the burden of pollution treatment for production wastewater, achieving low-cost and environmentally friendly production, and possessing high industrial value.

[0052] In S2, the shear rate is 10,000 r / min or higher. In some embodiments, in S2, the shear rate may be between 10,000 r / min and 28,000 r / min, and may be in the range of, for example, 10,000 r / min, 11,000 r / min, 12,000 r / min, 13,000 r / min, 14,000 r / min, 15,000 r / min, 16,000 r / min, 17,000 r / min, 18,000 r / min, 19,000 r / min, 20,000 r / min, 21,000 r / min, 22,000 r / min, 23,000 r / min, 24,000 r / min, 25,000 r / min, 26,000 r / min, 27,000 r / min, 28,000 r / min or any of the above values.

[0053] Controlling the magnitude of the shear rate also contributes to obtaining cathode active material precursors with different particle sizes. Therefore, the manufacturing method according to this application also contributes to accurately controlling the particle size of the cathode active material precursor.

[0054] In S2, the order in which the precipitant aqueous solution and the metal salt aqueous solution are added is not particularly limited. For example, both may be added to the reaction vessel simultaneously, or the metal salt aqueous solution may be added first, followed by the precipitant aqueous solution. Selectively, in S2, by adding the precipitant aqueous solution to the metal salt aqueous solution at a shear rate of 10,000 r / min or more, mixing them, and then carrying out the coprecipitation reaction, the initial concentration of the reaction system can be instantaneously increased by the shear action of the high-speed homogenizer, allowing the metal salt and precipitant to directly undergo a coprecipitation reaction.

[0055] In some embodiments, the duration of the coprecipitation reaction in S2 may be 10 min to 60 min.

[0056] In some embodiments, the temperature of the coprecipitation reaction in S2 may be 20°C to 80°C.

[0057] In some embodiments, the concentration of the metal salt aqueous solution in S1 may be 0.5 mol / L to 2 mol / L.

[0058] In some embodiments, in S1, the aqueous metal salt solution is prepared by dissolving the metal salt in water in a protective gas atmosphere containing nitrogen gas, an inert gas, or a combination thereof to form an aqueous metal salt solution.

[0059] In some embodiments, the metal salt may be a water-soluble metal salt known in the art for preparing cathode active material precursors, and may include, for example, one or more selected from metal sulfates, nitrates, hydrochlorides, and acetates.

[0060] In some embodiments, the metal salt may be a divalent metal salt.

[0061] The manufacturing method described in this application can produce precursors for lithium manganese iron phosphate cathode active material, lithium nickel cobalt manganate cathode active material, and lithium-rich manganese cathode active material.

[0062] In some embodiments, the metal salt may include one or more selected from divalent Mn salts, Fe salts, Ni salts, Co salts, Mg salts, Zn salts, Ca salts, Ti salts, V salts, and Cr salts.

[0063] In some embodiments, the metal salt may include at least a divalent Mn salt.

[0064] In some embodiments, the metal salt may include a divalent Mn salt, an Fe salt, and a salt of another selectable metal M1, where M1 represents doping elements for manganese and iron sites, and the salt of the other metal M1 may optionally include one or more selected from divalent Ni salts, Co salts, Mg salts, Zn salts, Ca salts, Ti salts, V salts, and Cr salts, thereby enabling the production of a precursor for lithium manganese iron phosphate cathode active material.

[0065] In some embodiments, the metal salt may include a divalent Mn salt, Ni salt, Co salt, and a salt of another selectable metal M2, where M2 represents a doping element of manganese, nickel, and cobalt sites. Optionally, the salt of the other metal M2 includes one or more selected from divalent Fe, Mg, Zn, Ca, Ti, V, and Cr salts. This allows for the production of a precursor for lithium nickel-cobalt manganese oxide cathode active material.

[0066] In some embodiments, the metal salt may include a divalent Mn salt, a Ni salt, and a salt of another selectable metal M3, where M3 represents doping elements for manganese and nickel sites. Optionally, the salt of the other metal M3 includes one or more selected from divalent Fe salts, Co salts, Mg salts, Zn salts, Ca salts, Ti salts, V salts, and Cr salts. This allows for the production of a precursor for lithium-rich manganese cathode active material.

[0067] In some examples, the concentration of the aqueous solution of the precipitating agent may be 0.5 mol / L to 2 mol / L.

[0068] The precipitating agent comprises one or more selected from oxalic acid and water-soluble oxalates. In some examples, the water-soluble oxalate optionally comprises one or more selected from lithium oxalate, sodium oxalate, potassium oxalate, and ammonium oxalate.

[0069] In some embodiments, the molar ratio of the precipitant to the metal salt may be 1:1 to 3:1. By adjusting the amount of precipitant used, it is possible to improve the conversion efficiency of metal ions, reduce the difference in precipitation rates of different metal ions in the reaction system, thereby contributing to uniform coprecipitation of metal ions, and further to accurately control the composition of the positive electrode active material precursor, making it possible to set the actual content of each metal ion in the obtained positive electrode active material precursor to a predetermined value. By adjusting the amount of precipitant used, it is also possible to make the degree of coprecipitation more complete, significantly reduce the content of metal ions in the reaction wastewater, reduce the difficulty of the post-treatment wastewater treatment process, reduce environmental pollution, and improve the purity of the obtained positive electrode active material precursor, thereby reducing the content of impurities.

[0070] In some embodiments, the metal salt aqueous solution may further contain a complexing agent.

[0071] When producing cathode active material precursors by coprecipitation, differences in the solubility product constants of different metal ions result in differences in the precipitation rates of different metal ions, making it difficult to achieve uniform coprecipitation of metal ions. Simultaneously, there are significant differences between the proportion of each metal ion in the obtained cathode active material precursor particles and the proportion of each metal ion in the raw materials, affecting the performance and consistency of the product. Complexing agents can complex metal ions, achieving the objective of controlling free metal ions, improving the precipitation conversion efficiency of metal ions, reducing differences in precipitation rates in the reaction system of different metal ions, achieving uniform coprecipitation of metal ions, and further achieving precise control of the composition of the cathode active material precursor, thereby setting the actual content of each metal ion in the obtained cathode active material precursor to a predetermined value. Therefore, by adding a complexing agent to an aqueous metal salt solution, the purity of the obtained cathode active material precursor is improved, the impurity content is reduced, and the difference between the proportion of each metal ion in the obtained cathode active material precursor particles and the proportion of each metal ion in the raw materials is reduced, allowing for precise control of the composition of the cathode active material precursor.

[0072] In some examples, the complexing agent may include one or more selected from aminocarboxylic acid salts, hydroxycarboxylic acid salts, and organic phosphonates. Selectively, the complexing agent may include one or more selected from ethylenediaminetetraacetate, gluconate, citrate, tartrate, metasilicate, tripolyphosphate, nitrilotriacetic acid, diethylenetriaminepentamethylenephosphonate, ethylenediaminetetrakismethylenephosphonate, and hydroxyethanediphosphonate. More selectively, the complexing agent may include one or more selected from ethylenediaminetetraacetate sodium, gluconate sodium, citrate sodium, tartrate sodium, metasilicate sodium, tripolyphosphate sodium, nitrilotriacetic acid, diethylenetriaminepentamethylenephosphonate sodium, ethylenediaminetetrakismethylenephosphonate sodium, and hydroxyethanediphosphonate sodium.

[0073] In some examples, the content of the complexing agent is ≤10 wt% relative to the total mass of the metal salt aqueous solution, and may be selectably between 1 wt% and 10 wt%.

[0074] In some embodiments, in S3, the cleaning method may include one or more of water washing and alcohol washing, or it may optionally include water washing and alcohol washing simultaneously. In this application, the number of times water washing and alcohol washing are performed is not particularly limited and may be, for example, 2 to 6 times. Optionally, the alcohol washing is performed with ethanol.

[0075] This application does not impose any particular restrictions on the drying method and can be adjusted according to the actual situation. In some embodiments, in S3, the drying process may be either a spray drying process or a vacuum drying process.

[0076] In some embodiments, in S3, the drying process may include the step of drying the washed material in a vacuum oven, then transferring it to a tubular furnace to continue the drying process, thereby obtaining an anhydrous cathode active material precursor. This contributes to precisely controlling the proportion of each element in the cathode active material subsequently produced.

[0077] Selectively, the drying temperature of the vacuum oven is 60°C-100°C, and the drying time in the vacuum oven is 6-24 hours. Selectively, the drying temperature in the tubular furnace is 200°C-300°C, and the drying time in the tubular furnace is 2-8 hours.

[0078] Optionally, the atmosphere inside the tubular furnace is a protective gas atmosphere, and the protective gas includes nitrogen gas, an inert gas, or a combination thereof. Optionally, the inert gas is helium gas, argon gas, or a combination thereof.

[0079] In the method for producing a positive electrode active material precursor provided in this application, unless otherwise specified, each raw material and the equipment used can be obtained by direct purchase.

[0080] A second embodiment of the present application provides a positive electrode active material precursor manufactured by the method described in the first embodiment of the present application.

[0081] The molecular formula of the precursor of the positive electrode active material is Fe x Mn y M1 1-x-y C2O4, Ni a Co b Mn c M2 1-a-b-c C2O4 or Ni p Mn q M3 1-p-qIt may be C2O4, where 0 < x < 1, 0 < y < 1, and 0 ≤ 1 - x - y < 1. M1 represents the doping elements of the manganese site and the iron site, and optionally includes one or more selected from Ni, Co, Mg, Zn, Ca, Ti, V, and Cr. Here, 0 < a < 1, 0 < b < 1, 0 < c < 1, and 0 ≤ 1 - a - b - c < 1. M2 represents the doping elements of the manganese site, the nickel site, and the cobalt site, and optionally includes one or more selected from Fe, Mg, Zn, Ca, Ti, V, and Cr. Here, 0 < p < 1, 0 < q < 1, and 0 ≤ 1 - p - q < 1. M3 represents the doping elements of the manganese site and the nickel site, and optionally includes one or more selected from Fe, Co, Mg, Zn, Ca, Ti, V, and Cr.

[0082] The cathode active material precursor of this application has the characteristics of regular morphology, small particle size, narrow particle size distribution, single crystal phase, high purity, uniform element distribution, and high batch stability and consistency. Therefore, it can improve the electrochemical performance of the cathode active material and the secondary battery.

[0083] In some embodiments, the volume particle size Dv50 of the cathode active material precursor satisfies 0.3 μm ≤ Dv50 ≤ 3 μm.

[0084] In some embodiments, the volume particle sizes Dv90 and Dv50 of the cathode active material precursor satisfy 1 < Dv90 / Dv50 ≤ 1.5.

[0085] The third aspect of the embodiment of this application provides a method for manufacturing a cathode active material, including mixing the cathode active material precursor manufactured by the method described in the first aspect of the embodiment of this application or the cathode active material precursor of the second aspect of the embodiment of this application with a lithium source and / or a phosphorus source at a predetermined ratio, and then performing a sintering process to obtain a cathode active material.

[0086] In some embodiments, the molecular formula of the cathode active material precursor is Fe x Mn y M1 1-x-yIt is C2O4, where 0 < x < 1, 0 < y < 1, 0 ≤ 1 - x - y < 1, M1 represents the doping element of the manganese site and the iron site, and optionally contains one or more selected from Ni, Co, Mg, Zn, Ca, Ti, V, and Cr. The method for manufacturing the positive electrode active material is Fe x Mn y M1 1-x-y including the step of obtaining a positive electrode active material by mixing C2O4, a lithium source, a phosphorus source, and an optional carbon source in a predetermined ratio and then performing a sintering treatment. The molecular formula of the positive electrode active material is LiFe x Mn y M1 1-x-y PO4 may also be used.

[0087] In some embodiments, the molecular formula of the positive electrode active material precursor is Ni a Co b Mn c M2 1-a-b-c It is C2O4, where 0 < a < 1, 0 < b < 1, 0 < c < 1, 0 ≤ 1 - a - b - c < 1, M2 represents the doping element of the manganese site, the nickel site, and the cobalt site, and optionally contains one or more selected from Fe, Mg, Zn, Ca, Ti, V, and Cr. The method for manufacturing the positive electrode active material is Ni a Co b Mn c M2 1-a-b-c including the step of obtaining a positive electrode active material by mixing C2O4 and a lithium source in a predetermined ratio and then performing a sintering treatment. The molecular formula of the positive electrode active material is LiNi a Co[[ID=3​​​​​​​​​​​​​​It is C2O4, where 0 < p < 1, 0 < q < 1, 0 ≤ 1 - p - q < 1. M3 represents the doping elements of the manganese site and the nickel site, and optionally may include one or more selected from Fe, Co, Mg, Zn, Ca, Ti, V, and Cr. The method for manufacturing the positive electrode active material is Ni p Mn q M3 1-p-q It may include the step of obtaining a positive electrode active material by mixing C2O4 and a lithium source in a predetermined ratio and then performing a sintering process. The molecular formula of the positive electrode active material may be mLi2MnO3·(1 - m)LiMO2, where 0 < m < 1, and M includes one or more selected from Mn, Ni, Fe, Co, Mg, Zn, Ca, Ti, V, and Cr.

[0089] The lithium source may be a lithium-containing compound that can be used in the manufacture of positive electrode active materials known in the art. For example, the lithium source may include those selected from Li2CO3, LiOH, or a combination thereof.

[0090] The phosphorus source may be a phosphorus-containing compound that can be used in the manufacture of lithium manganese iron phosphate positive electrode active materials known in the art. For example, the phosphorus source may include one or more of (NH4)2HPO4, NH4H2PO4, (NH4)3PO4, and H3PO4.

[0091] The carbon source includes one or more of an organic carbon source and an inorganic carbon source, and optionally may include one or more of glucose, sucrose, starch, fructose, polyvinyl alcohol, polyethylene glycol, and citric acid.

[0092] The fourth aspect of the embodiment of the present application provides a positive electrode active material manufactured by the method described in the third aspect of the embodiment of the present application. The positive electrode active material may be a lithium manganese iron phosphate positive electrode active material, a lithium nickel cobalt manganese oxide positive electrode active material, or a lithium-rich manganese-based positive electrode active material.

[0093] A fifth embodiment of the present application provides a secondary battery comprising a positive electrode active material manufactured by the method of the third embodiment of the present application or a positive electrode active material of the fourth embodiment of the present application. Examples

[0094] The following examples are intended to illustrate the disclosures of this application in more detail, and are merely illustrative, as it will be obvious to those skilled in the art that various modifications and changes can be made within the scope of the disclosures of this application. Unless otherwise specified, all parts, percentages, and ratios reported in the following examples are on a weight basis, and all reagents used in the examples are commercially available or can be synthesized according to conventional methods and used directly without further processing. Furthermore, all equipment used in the examples can be obtained commercially. Example 1 S1. Preparation of metal salt aqueous solution and precipitant aqueous solution

[0095] Under the protection of nitrogen gas, ferrous sulfate and manganese sulfate were prepared in a reaction vessel in a Fe:Mn molar ratio of 4:6 with pure water to create a 0.5 mol / L aqueous solution of the metal salt. 5 wt% sodium ethylenediaminetetraacetate was then added as a complexing agent. A 0.75 mol / L aqueous solution of oxalic acid and pure water was prepared as a precipitating agent and ready for use. S2. Coprecipitation reaction

[0096] After manually adjusting the rotation speed of the high-speed homogenizer to 12,000 r / min, the aqueous solution of the precipitating agent was rapidly added to the reaction vessel under the high-speed dispersion and shearing action of the high-speed homogenizer, and the shearing reaction was carried out for 30 minutes to obtain a suspension. The reaction temperature was room temperature (25°C), and the molar ratio of the metal salt to oxalic acid used was 1:1.5. S3.Drying

[0097] The obtained suspension was washed multiple times with deionized water and ethanol, then centrifuged to collect the solid components. The collected solid components were dried in a vacuum oven at 80°C. Finally, the dried sample was placed in a tubular furnace and heated at 200°C for 2 hours under an argon gas atmosphere to remove the water of crystallization. Anhydrous Mn 0.6 Fe 0.4 A C2O4 precursor was obtained. Example 2 S1. Preparation of metal salt aqueous solution and precipitant aqueous solution

[0098] Under the protection of nitrogen gas, ferrous sulfate and manganese sulfate were prepared in a reaction vessel in a Fe:Mn molar ratio of 4:6 with pure water to create a 0.5 mol / L aqueous solution of the metal salt, and 3 wt% sodium citrate was added as a complexing agent. A 1.5 mol / L aqueous solution of the precipitating agent, oxalic acid, and pure water was prepared for use. S2. Coprecipitation reaction

[0099] After manually adjusting the rotation speed of the high-speed homogenizer to 28,000 r / min, the aqueous solution of the precipitating agent was rapidly added to the reaction vessel under the high-speed dispersion and shearing action of the high-speed homogenizer, and the shearing reaction was carried out for 10 minutes to obtain a suspension. The reaction temperature was room temperature (25°C), and the molar ratio of the metal salt to oxalic acid used was 1:3. S3.Drying

[0100] The obtained suspension was washed multiple times with deionized water and ethanol, then centrifuged to collect the solid components. The collected solid components were dried in a vacuum oven at 80°C. Finally, the dried sample was placed in a tubular furnace and heated in an argon gas atmosphere at 200°C for 2 hours to remove the water of crystallization. Anhydrous Mn 0.6 Fe 0.4 A C2O4 precursor was obtained. Example 3 S1. Preparation of metal salt aqueous solution and precipitant aqueous solution

[0101] Under the protection of nitrogen gas, ferrous sulfate and manganese sulfate were prepared in a reaction vessel in a Fe:Mn molar ratio of 3:7 in pure water to a 0.5 mol / L aqueous solution of the metal salt, and 10 wt% sodium diethylenetriaminepentamethylenephosphonate was added as a complexing agent. A 0.5 mol / L aqueous solution of the precipitating agent, sodium oxalate, and pure water was prepared for use. S2. Coprecipitation reaction

[0102] After manually adjusting the rotation speed of the high-speed homogenizer to 10,000 r / min, the aqueous solution of the precipitating agent was rapidly added to the reaction vessel under the high-speed dispersion and shearing action of the high-speed homogenizer, and the shearing reaction was carried out for 40 minutes to obtain a suspension. The reaction temperature was room temperature (25°C), and the molar ratio of the metal salt to sodium oxalate used was 1:1. S3.Drying

[0103] The obtained suspension was washed multiple times with deionized water and ethanol, then centrifuged to collect the solid components. The collected solid components were dried in a vacuum oven at 80°C. Finally, the dried sample was placed in a tubular furnace and heated at 200°C for 2 hours under an argon gas atmosphere to remove the water of crystallization. Anhydrous Mn 0.7 Fe 0.3 A C2O4 precursor was obtained. Example 4 S1. Preparation of metal salt aqueous solution and precipitant aqueous solution

[0104] Under the protection of nitrogen gas, nickel sulfate and manganese sulfate were prepared in a reaction vessel in a Ni:Mn molar ratio of 3:7 with pure water to create a 0.5 mol / L aqueous solution of the metal salt. Furthermore, 5 wt% sodium ethylenediaminetetrakismethylenephosphonate was added as a complexing agent. A 1 mol / L aqueous solution of the precipitating agent, oxalic acid, and pure water was prepared for use. S2. Coprecipitation reaction

[0105] After manually adjusting the rotation speed of the high-speed homogenizer to 15,000 r / min, the aqueous solution of the precipitating agent was rapidly added to the reaction vessel under the high-speed dispersion and shearing action of the high-speed homogenizer, and the shearing reaction was carried out for 30 minutes to obtain a suspension. The reaction temperature was room temperature (25°C), and the molar ratio of the metal salt to oxalic acid used was 1:2. S3.Drying

[0106] The obtained suspension was washed multiple times with deionized water and ethanol, then centrifuged to collect the solid components. The collected solid components were dried in a vacuum oven at 80°C. Finally, the dried sample was placed in a tubular furnace and heated at 200°C for 2 hours under an argon gas atmosphere to remove the water of crystallization. Anhydrous Mn 0.7 Ni 0.3 A C2O4 precursor was obtained. Example 5 S1. Preparation of metal salt aqueous solution and precipitant aqueous solution

[0107] Under the protection of nitrogen gas, nickel sulfate, cobalt sulfate, and manganese sulfate were prepared in a reaction vessel as a 0.5 mol / L aqueous metal salt solution with a molar ratio of Ni:Co:Mn of 1:1:1 using pure water. 5 wt% sodium gluconate was then added as a complexing agent. A 0.5 mol / L aqueous solution of the precipitating agent, ammonium oxalate, and pure water was prepared for use. S2. Coprecipitation reaction

[0108] After manually adjusting the rotation speed of the high-speed homogenizer to 20,000 r / min, the aqueous solution of the precipitating agent was rapidly added to the reaction vessel under the high-speed dispersion and shearing action of the high-speed homogenizer, and the shearing reaction was carried out for 20 minutes to obtain a suspension. The reaction temperature was room temperature (25°C), and the molar ratio of the metal salt to ammonium oxalate used was 1:1. S3.Drying

[0109] The obtained suspension was washed multiple times with deionized water and ethanol, then centrifuged to collect the solid components. The collected solid components were dried in a vacuum oven at 80°C. Finally, the dried sample was placed in a tubular furnace and heated in an argon gas atmosphere at 200°C for 2 hours to remove the water of crystallization. Anhydrous Ni0.33 Co 0.33 Mn 0.33 A C2O4 precursor was obtained. Comparative Example 1 S1. Preparation of metal salt aqueous solution and precipitant aqueous solution

[0110] Under the protection of nitrogen gas, ferrous sulfate and manganese sulfate were prepared in a reaction vessel in a Fe:Mn molar ratio of 4:6 with pure water to create a 0.5 mol / L aqueous solution of the metal salt, and 3 wt% sodium citrate was added as a complexing agent. A 1.5 mol / L aqueous solution of the precipitating agent, oxalic acid, and pure water was prepared for use. S2. Coprecipitation reaction

[0111] Under the stirring action of a magnetic stirrer, the aqueous solution of the precipitant was added to the reaction vessel and stirred for 60 minutes to obtain a suspension. The reaction temperature was room temperature (25°C), the stirring speed was 800 r / min, and the molar ratio of the metal salt to oxalic acid used was 1:3. S3.Drying

[0112] The obtained suspension was washed multiple times with deionized water and ethanol, then centrifuged to collect the solid components. The collected solid components were dried in a vacuum oven at 80°C. Finally, the dried sample was placed in a tubular furnace and heated at 200°C for 2 hours under an argon gas atmosphere to remove the water of crystallization. Anhydrous Mn 0.6 Fe 0.4 A C2O4 precursor was obtained. Comparative Example 2 S1. Preparation of metal salt aqueous solution and precipitant aqueous solution

[0113] Under the protection of nitrogen gas, ferrous sulfate and manganese sulfate were prepared in a reaction vessel in a Fe:Mn molar ratio of 3:7 in pure water and a 0.5 mol / L aqueous solution of the metal salt. A 0.5 mol / L aqueous solution of the precipitant, sodium oxalate, and pure water was prepared for use. S2. Coprecipitation reaction

[0114] Under the stirring action of a magnetic stirrer, the aqueous solution of the precipitant was added to the reaction vessel and stirred for 60 minutes to obtain a suspension. The reaction temperature was room temperature (25°C), the stirring speed was 500 r / min, and the molar ratio of the metal salt to sodium oxalate used was 1:1. S3.Drying

[0115] The obtained suspension was washed multiple times with deionized water and ethanol, then centrifuged to collect the solid components. The collected solid components were dried in a vacuum oven at 80°C. Finally, the dried sample was placed in a tubular furnace and heated at 200°C for 2 hours under an argon gas atmosphere to remove the water of crystallization. Anhydrous Mn 0.7 Fe 0.3 A C2O4 precursor was obtained. Test section (1) Particle size test

[0116] The volume particle size of the oxalate precursor prepared above was measured using a Malvern Master Size 3000 laser particle size analyzer. Dv50 and Dv90 refer to the particle size corresponding to when the cumulative volume distribution percentage of the material reaches 50% and 90%, respectively. GB / T 19077-2016 can be referred to as the test standard.

[0117] The test results are shown in Table 1. (2) Testing of the content of metallic elements

[0118] Using a Plasma 3000 inductively coupled plasma atomic emission spectrometer, the content of each metal element in the oxalate precursor prepared above was measured by the ICP-OES method, and their molar ratios were calculated.

[0119] The test results are shown in Table 2. (3) Initial cycle performance test of coin cells

[0120] The above-prepared oxalate precursor (100 mmol), Li2CO3 (50 mmol), NH4H2PO4 (100 mmol), and sucrose (15 mmol) were placed in a ball mill tank, a small amount of ethanol and water were added as solvents, and the mixture was ball milled at a rotation speed of 500 r / min for 8 hours to obtain a slurry. The obtained slurry was transferred to a spray dryer and spray-dried to obtain a powder, with the drying temperature set to 210°C. The obtained powder was placed in a muffle furnace and sintered at 400°C in an air atmosphere for 5 hours, then allowed to cool naturally to room temperature to obtain a pre-sintered material. The obtained pre-sintered material was placed in a ball mill tank, a small amount of ethanol and water were added as solvents, and the mixture was ball milled at a rotation speed of 800 r / min for 4 hours to obtain a slurry. The obtained slurry was transferred to a spray dryer and spray-dried to obtain a pre-sintered material powder. The drying temperature was set to 210°C, and the obtained pre-sintered material powder was placed in a muffle furnace and sintered at 700°C under a nitrogen gas atmosphere for 10 hours. After natural cooling to room temperature, it was pulverized with airflow to obtain a lithium iron manganese phosphate cathode active material.

[0121] The prepared lithium manganese iron phosphate cathode active material, polyvinylidene fluoride (PVDF) as a binder, and acetylene black as a conductive agent were added to N-methylpyrrolidone (NMP) in a weight ratio of 90:5:5, and the mixture was stirred in a drying chamber to prepare a slurry. The slurry was applied to aluminum foil, dried, and cold-pressed to form a cathode sheet.

[0122] A lithium sheet was used as the negative electrode, and a solution of ethylene carbonate (EC), diethyl carbonate (DEC), and dimethyl carbonate (DMC) in a volume ratio of 1 mol / L LiPF6 was used as the electrolyte. This solution was then assembled into a coin cell in a coin cell box along with the prepared positive electrode sheet.

[0123] Under constant temperature conditions of 25°C, the coin cell is charged to 4.3V with a constant current of 0.1C, then charged at a constant voltage of 4.3V until the current drops to 0.05mA or less. The charge capacity at this point is the initial charge capacity and is defined as C0. After the coin cell is left to stand for 2 minutes, it is discharged at a constant current of 0.1C to 2.0V. The discharge capacity at this point is the initial discharge capacity and is defined as D0.

[0124] The initial Coulomb efficiency (%) of a coin cell is (D0 / C0) × 100%. The initial gram capacity (initial capacity per gram) (mAh / g) of a coin cell is D0 / m, where m represents the mass of the lithium manganese iron phosphate cathode active material.

[0125] The test results are shown in Table 3 and Figure 3.

[0126] [Table 1]

[0127] [Table 2]

[0128] [Table 3]

[0129] Figure 1 is a scanning electron microscope (SEM) image of the positive electrode active material precursor produced in Example 3, with a magnification of 1000x in Figure 1(a) and a magnification of 5000x in Figure 1(b). Figure 2 is a scanning electron microscope (SEM) image of the positive electrode active material precursor produced in Comparative Example 2, with a magnification of 2000x in Figure 2(a) and a magnification of 5000x in Figure 2(b).

[0130] In summary, the measurement results in Tables 1 and 2, along with Figures 1 and 2, show that the positive electrode active material precursor produced by the manufacturing method of this application has the characteristics of being well-formed, having a small particle size, a narrow particle size distribution, and a uniform elemental distribution. Furthermore, in summary, the test results of Examples 1-5 show that the higher the rotation speed (i.e., shear rate) of the high-speed homogenizer, the smaller the particle size and the narrower the particle size distribution of the obtained positive electrode active material precursor.

[0131] Furthermore, a comprehensive examination of the test results from Example 3 and Comparative Example 2 reveals that by adding a complexing agent to the metal salt aqueous solution, the composition of the positive electrode active material precursor can be precisely controlled, and the actual content of each metal ion in the obtained positive electrode active material precursor reaches a predetermined value.

[0132] Furthermore, a comprehensive examination of the test results from Example 1, Example 2, and Comparative Example 1 reveals that when a complexing agent is added to an aqueous metal salt solution, the manufacturing method according to this application allows for precise control of the composition of the positive electrode active material precursor, and also enables the actual content of each metal ion in the obtained positive electrode active material precursor to be brought closer to a predetermined value.

[0133] Figure 3 shows the initial charge-discharge curves of the coin cells manufactured in Example 1, Example 2, and Comparative Example 1. As can be seen from the test results in Table 3 and Figure 3, the lithium iron manganese phosphate cathode active material manufactured using the cathode active material precursor manufactured in this application has a higher gram capacity and initial Coulomb efficiency, thereby better improving the electrochemical performance of the secondary battery.

[0134] This application is not limited to the embodiments described above. The embodiments described above are illustrative only, and any embodiments that have a configuration substantially identical to the technical idea and produce similar effects within the technical scope of this application are all included within the technical scope of this application. Furthermore, any modifications to the embodiments that a person skilled in the art could conceive, or other forms constructed by combining some of the components of the embodiments, are also included within the scope of this application, as long as they do not depart from the spirit of this application.

Claims

1. A method for producing a positive electrode active material precursor, Step S1 involves preparing an aqueous solution of a metal salt and an aqueous solution of a precipitating agent, wherein the precipitating agent includes one or more types selected from oxalic acid and water-soluble oxalates. Step S2 involves mixing the aqueous solution of the precipitating agent and the aqueous solution of the metal salt at a shear rate of 10,000 r / min or more, and then carrying out a coprecipitation reaction. Step S3 involves washing and drying after the reaction is complete to obtain the positive electrode active material precursor, A method for producing a positive electrode active material precursor, which includes [the specified component].

2. The method according to claim 1, wherein in S2, the coprecipitation reaction is carried out in a high-speed homogenizer.

3. In S2, the shear rate is 10000 r / min - 28000 r / min, and / or In S2, the time of the coprecipitation reaction is 10 min to 60 min, and / or In S2, the temperature of the coprecipitation reaction is 20°C to 80°C. The method according to claim 1.

4. The method according to claim 1, wherein in S2, the molar ratio of the amount of precipitant to the amount of the metal salt used is 1:1 to 3:

1.

5. In S1, the concentration of the metal salt aqueous solution is 0.5 mol / L - 2 mol / L, and / or In S1, the concentration of the aqueous solution of the precipitating agent is 0.5 mol / L to 2 mol / L. The method according to claim 1.

6. The method according to claim 1, wherein the aqueous metal salt solution is prepared by dissolving a metal salt in water to form an aqueous metal salt solution under a protective gas atmosphere containing nitrogen gas, an inert gas, or a combination thereof.

7. In S1, the metal salt comprises one or more selected from metal sulfates, nitrates, hydrochlorides, and acetates, and / or The method according to claim 1, wherein in S1, the water-soluble oxalate comprises one or more selected from lithium oxalate, sodium oxalate, potassium oxalate, and ammonium oxalate.

8. The method according to claim 1, wherein in S1, the metal salt is a divalent metal salt.

9. The method according to claim 1, wherein the metal salt comprises one or more selected from divalent Mn salts, Fe salts, Ni salts, Co salts, Mg salts, Zn salts, Ca salts, Ti salts, V salts, and Cr salts.

10. The method according to claim 9, wherein the metal salt comprises at least a divalent Mn salt.

11. The aforementioned metal salts include divalent Mn salts, Fe salts, and salts of other metals M1, where M1 represents doping elements of manganese and iron sites. Alternatively, the metal salt includes divalent Mn salts, Ni salts, Co salts, and salts of other metals M2, where M2 represents doping elements of manganese site, nickel site, and cobalt site. Alternatively, the metal salt may include a divalent Mn salt, a Ni salt, and a salt of another metal M3, where M3 represents doping elements of manganese site and nickel site. The method according to claim 1.

12. The aforementioned metal salt aqueous solution further comprises a complexing agent. The method according to claim 1.

13. The complexing agent comprises one or more selected from ethylenediaminetetraacetate, gluconate, citrate, tartrate, metasilicate, tripolyphosphate, nitrilotriacetate, diethylenetriaminepentamethylenephosphonate, ethylenediaminetetrakismethylenephosphonate, and hydroxyethanediphosphonate, and / or The content of the complexing agent is 10 wt% or less relative to the total mass of the metal salt aqueous solution. The method according to claim 12.

14. The manufactured cathode active material precursor has a molecular formula of Fe ｘ Mn ｙ M1 １－ｘ－ｙ C ２ O ４ , Ni ａ Co ｂ Mn ｃ M2 １－ａ－ｂ－ｃ C ２ O ４ or Ni ｐ Mn ｑ M3 １－ｐ－ｑ C ２ O ４ where 0 < x < 1, 0 < y < 1, 0 ≤ 1 - x - y < 1, M1 represents the doping elements of the manganese site and the iron site, 0 < a < 1, 0 < b < 1, 0 < c < 1, 0 ≤ 1 - a - b - c < 1, M2 represents the doping elements of the manganese site, the nickel site and the cobalt site, 0 < p < 1, 0 < q < 1, 0 ≤ 1 - p - q < 1, and M3 represents the doping elements of the manganese site and the nickel site. The method according to claim 1.

15. The volume particle size Dv50 of the positive electrode active material precursor satisfies 0.3 μm ≤ Dv50 ≤ 3 μm, and / or The method according to claim 14, wherein the volume particle sizes Dv90 and Dv50 of the positive electrode active material precursor satisfy 1 < Dv90 / Dv50 ≤ 1.

5.

16. A method for producing a positive electrode active material, comprising the steps of mixing a positive electrode active material precursor produced by the method of any one of claims 1 to 15 with a lithium source and / or a phosphorus source in a predetermined ratio, and then sintering the mixture to obtain a positive electrode active material.

Images