Continuous reaction system, iron manganese phosphate precursor, lithium iron manganese phosphate, and method for producing the same and secondary battery

Abstract

The present application provides a continuous reaction system, an iron manganese phosphate precursor, lithium iron manganese phosphate, and a method for producing the same and a secondary battery. The method for producing an iron manganese phosphate precursor provided by the present application is a continuous method, which can improve production efficiency and at the same time provide an iron manganese phosphate precursor with small particle size, narrow particle size distribution, high crystallinity, single crystallites, regular shape, high tap density, and high batch production stability and consistency.

Description

Technical Field

[0001] This application belongs to the field of battery technology, and specifically relates to a continuous reaction system, manganese iron phosphate precursor, lithium manganese iron phosphate, its manufacturing method, and a secondary battery.

Background Art

[0002] In recent years, secondary batteries have been widely applied in multiple fields such as energy storage power systems in hydropower, thermal power, wind power, and solar power plants, as well as electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc. With the application and popularization of secondary batteries, their safety performance has attracted increasing attention. Lithium manganese iron phosphate is one of the most prominent cathode active materials currently due to its advantages such as large capacity, high safety performance, and abundant raw material supply sources. Manganese iron phosphate is one of the important raw materials for manufacturing lithium manganese iron phosphate, and the impact of its performance on the performance of lithium manganese iron phosphate and secondary batteries is extremely important. However, currently, all manganese iron phosphates are obtained by using an intermittent manufacturing method, so there are problems such as low manufacturing efficiency, complicated processes, difficulty in controlling the manufacturing process, large fluctuations in product quality, and poor stability and consistency in batch production.

Summary of the Invention

[0003] The object of this application is to provide a continuous reaction system, manganese iron phosphate precursor, lithium manganese iron phosphate, its manufacturing method, and a secondary battery, aiming to improve the manufacturing efficiency of the manganese iron phosphate precursor and obtain a manganese iron phosphate precursor with small particle size, narrow particle size distribution, high crystallinity, single microcrystal, regular shape, high tap density, and high stability and consistency in batch production.

[0004] According to the first aspect of the present application, a continuous reaction system for manufacturing an iron manganese phosphate precursor is provided. The continuous reaction system includes a first material dissolution kettle, a second material dissolution kettle, a first reaction kettle, a second reaction kettle, and an aging kettle. The first reaction kettle, the second reaction kettle, and the aging kettle are connected in series in sequence via pipelines. The first material dissolution kettle is used to contain a metal salt solution necessary for manufacturing the iron manganese phosphate precursor. The second material dissolution kettle is used to contain an oxidizing agent and a phosphorus source solution necessary for manufacturing the iron manganese phosphate precursor. The first reaction kettle has a first supply port and a first overflow port. The first supply port of the first reaction kettle communicates with the first material dissolution kettle and the second material dissolution kettle via a first pipeline and a second pipeline respectively. Thereby, the first reaction kettle contains and mixes the metal salt solution and the phosphorus source solution and then reacts them to generate a first reaction solution. A first shut-off valve and a first metering pump are installed in the first pipeline to adjust the flow rate of the metal salt solution. A second shut-off valve and a second metering pump are installed in the second pipeline to adjust the flow rate of the phosphorus source solution. The second reaction kettle has a second supply port and a second overflow port. The second supply port of the second reaction kettle communicates with the first overflow port of the first reaction kettle via a third pipeline. Thereby, the second reaction kettle contains the first reaction solution from the first reaction kettle and continuously reacts it to generate a second reaction solution. The aging kettle includes a third supply port and a third overflow port. The third supply port of the aging kettle communicates with the second overflow port of the second reaction kettle via a fourth pipeline. Thereby, the aging kettle contains the second reaction solution from the second reaction kettle and continuously reacts it to generate a third reaction solution. When the liquid level of the third reaction solution is higher than the third overflow port of the aging kettle, the third reaction solution flows out via the third overflow port of the aging kettle.

[0005] According to the second aspect of the present application, a method for manufacturing an iron manganese phosphate precursor is provided. At least the first reaction kettle, the second reaction kettle, and the aging kettle are connected in series in sequence via pipelines. The first reaction kettle has a first supply port and a first overflow port. The first supply port of the first reaction kettle communicates with a first material dissolution kettle via a first pipeline, and the first supply port of the first reaction kettle communicates with a second material dissolution kettle via a second pipeline. A first shut-off valve and a first metering pump are installed in the first pipeline, and a second shut-off valve and a second metering pump are installed in the second pipeline. The second reaction kettle has a second supply port and a second overflow port. The second supply port of the second reaction kettle communicates with the first overflow port of the first reaction kettle via a third pipeline. The aging kettle includes a third supply port and a third overflow port. The third supply port of the aging kettle communicates with the second overflow port of the second reaction kettle via a fourth pipeline. Step S1, a metal salt solution required for manufacturing the iron manganese phosphate precursor is added to the first material dissolution kettle, a phosphorus source solution required for manufacturing an oxidizing agent and the iron manganese phosphate precursor is added to the second material dissolution kettle. The metal salt solution in the first material dissolution kettle is pumped into the first pipeline via the first shut-off valve and the first metering pump, and the phosphorus source solution in the second material dissolution kettle is pumped into the second pipeline via the second shut-off valve and the second metering pump. The metal salt solution and the phosphorus source solution are mixed and reacted in the first reaction kettle to generate a first reaction solution. When the liquid level of the first reaction solution is higher than the first overflow port of the first reaction kettle, the first reaction solution is automatically transported to the second reaction kettle to continue the reaction to generate a second reaction solution. When the liquid level of the second reaction solution is higher than the second overflow port of the second reaction kettle, the second reaction solution is automatically transported to the aging kettle to continue the reaction to generate a third reaction solution. When the liquid level of the third reaction solution is higher than the third overflow port of the aging kettle, the third reaction solution automatically flows out via the third overflow port of the aging kettle. During the reaction process, the first material dissolution kettle, the second material dissolution kettle, the first reaction kettle, the second reaction kettle, and the aging kettle are all under a protective gas atmosphere, and each kettle maintains a stirring state. Preferably, the protective gas includes nitrogen gas, an inert gas, or a combination thereof. Step S2, the third reaction solution obtained from the third overflow port of the aging kettle is filtered, washed, and dried to obtain an iron manganese phosphate precursor. Step S3, which includes.

[0006] The method for manufacturing the iron manganese phosphate precursor provided by this application has advantages such as high production efficiency, high energy efficiency, simple process, easy operation, and low labor cost, and is particularly suitable for large-scale industrial production. The method for manufacturing the iron manganese phosphate precursor provided by this application is a continuous manufacturing method. The iron manganese phosphate precursor obtained from the continuous manufacturing method provided by this application has small particle size, narrow particle size distribution, high crystallinity, single microcrystal, regular shape, high tap density, and high stability and consistency of batch production. The method for manufacturing the iron manganese phosphate precursor provided by this application can adjust the growth rate of crystal particles and the size and shape of crystal particles, thereby meeting different production requirements and manufacturing lithium iron manganese phosphate with different particle sizes.

[0007] In any embodiment of this application, a complexing agent is further added to the first material dissolving kettle. Preferably, the complexing agent includes one or more of aminocarboxylate, hydroxycarboxylate, and organic phosphonate. More preferably, it includes one or more of sodium nitrilotriacetate, disodium ethylenediaminetetraacetate, sodium gluconate, and sodium citrate. Thereby, spherical iron manganese phosphate precursor particles with high purity and uniform distribution of metal elements can be obtained, which have a higher tap density and can simultaneously achieve accurate control of the metal element content.

[0008] In any embodiment of this application, a surfactant is further added to the first material dissolving kettle. Preferably, the surfactant includes one or more of cetyltrimethylammonium bromide, sodium dodecylsulfonate, and polyvinylpyrrolidone. This helps to better adjust the shape of the iron manganese phosphate precursor particles.

[0009] In any embodiment of the present application, the reaction temperature of the first reaction kettle is lower than that of the second reaction kettle, and the reaction temperature of the aging kettle is lower than that of the second reaction kettle. Thereby, not only can the particle size of the obtained iron manganese phosphate precursor be adjusted, but also it helps to obtain iron manganese phosphate precursor particles with a narrow particle size distribution, high crystallinity, single microcrystals, regular shapes, and high tap density.

[0010] In any embodiment of the present application, the reaction temperature of the first reaction kettle is 70°C to 90°C.

[0011] In any embodiment of the present application, the reaction temperature of the second reaction kettle is 150°C to 250°C.

[0012] In any embodiment of the present application, the reaction temperature of the aging kettle is 20°C to 30°C.

[0013] In any embodiment of the present application, the flow rate of the metal salt solution in the first pipeline is 0.2 L / min to 2 L / min, preferably 0.25 L / min to 1 L / min.

[0014] In any embodiment of the present application, the flow rate of the phosphorus source solution in the second pipeline is 0.2 L / min to 2 L / min, preferably 0.25 L / min to 1 L / min.

[0015] In any embodiment of the present application, the flow rates of the metal salt solution and the phosphorus source solution are the same, which helps to improve the consistency of the obtained iron manganese phosphate precursor particles.

[0016] In any embodiment of the present application, the residence time of the iron manganese phosphate precursor in the first reaction kettle during the growth process is 1 h to 4 h.

[0017] In any embodiment of the present application, the residence time of the iron manganese phosphate precursor in the second reaction kettle during the growth process is 1 h to 16 h, preferably 4 h to 16 h.

[0018] In any embodiment of the present application, the residence time in the aging kettle during the growth process of the iron manganese phosphate precursor is 1 h to 48 h, preferably 12 h to 48 h.

[0019] In any embodiment of the present application, the volume of the first reaction kettle is less than or equal to the volume of the second reaction kettle. Preferably, the ratio of the volume of the first reaction kettle to the volume of the second reaction kettle is 1:(1 - 4), more preferably 1:(2 - 4). This helps the obtained iron manganese phosphate precursor particles to have a higher crystallinity.

[0020] In any embodiment of the present application, the volume of the first reaction kettle is less than or equal to the volume of the aging kettle. Preferably, the ratio of the volume of the first reaction kettle to the volume of the aging kettle is 1:(1 - 12), more preferably 1:(4 - 12). This helps the obtained iron manganese phosphate precursor to have a larger particle size.

[0021] In any embodiment of the present application, the volume of the second reaction kettle is less than or equal to the volume of the aging kettle. Preferably, the ratio of the volume of the second reaction kettle to the volume of the aging kettle is 1:(1 - 3), more preferably 1:(2 - 3). This helps the obtained iron manganese phosphate precursor to have a larger particle size.

[0022] In any embodiment of the present application, the metal salts required for manufacturing the iron manganese phosphate precursor include a water-soluble iron salt, a water-soluble manganese salt, and preferably a salt of a water-soluble doping element M. M represents a doping element for the manganese site and the iron site, and preferably includes one or more of Co, Mg, Zn, Ca, Ti, V, Ni, and Cr.

[0023] In any embodiment of the present application, preferably, the water-soluble iron salt includes one or more of ferrous chloride, ferrous nitrate, ferrous sulfate, ferrous acetate, ferric chloride, ferric nitrate, ferric sulfate, and ferric acetate.

[0024] In any embodiment of the present application, preferably, the water-soluble manganese salt contains one or more of manganese(I) chloride, manganese(I) nitrate, manganese(I) sulfate, and manganese(I) acetate.

[0025] In any embodiment of the present application, preferably, the salt of the water-soluble doping element M contains one or more of the hydrochloride, nitrate, sulfate, and acetate of the doping element M.

[0026] In any embodiment of the present application, the phosphorus source required for producing the manganese iron phosphate precursor contains one or more of phosphoric acid and water-soluble phosphates. Preferably, the water-soluble phosphate contains one or more of trisodium phosphate, tripotassium phosphate, ammonium hydrogen phosphate, diammonium hydrogen phosphate, and ammonium phosphate.

[0027] In any embodiment of the present application, the phosphorus source required for producing the manganese iron phosphate precursor further contains a water-soluble doping element Q source. Q represents the doping element of the phosphorus site and preferably contains one or more of B, S, Si, and N. Preferably, the doping element Q source contains one or more of the sulfate, borate, nitrate, and silicate of the doping element Q.

[0028] In any embodiment of the present application, the oxidizing agent contains one or more of hydrogen peroxide solution, nitric acid, sodium hypochlorite, potassium hypochlorite, sodium chlorate, and potassium chlorate, and preferably is hydrogen peroxide solution.

[0029] In any embodiment of the present application, the molar ratio of the metal salt to the oxidizing agent is 1:(0.1 - 1.2), and preferably is 1:(0.5 - 0.6).

[0030] In any embodiment of the present application, the concentration of the metal salt solution is 0.5 mol / L - 2 mol / L, and preferably is 0.5 mol / L - 1 mol / L.

[0031] In any embodiment of the present application, the concentration of the phosphorus source solution is 0.5 mol / L to 2 mol / L, preferably 0.5 mol / L to 1 mol / L.

[0032] In any embodiment of the present application, the molar ratio of the metal salt to the phosphorus source is 1:1 to 1:3.

[0033] In any embodiment of the present application, the stirring speed of the first material dissolving kettle is 100 r / min to 500 r / min.

[0034] In any embodiment of the present application, the stirring speed of the second material dissolving kettle is 100 r / min to 500 r / min.

[0035] In any embodiment of the present application, the stirring speed of the first reaction kettle is 100 r / min to 500 r / min.

[0036] In any embodiment of the present application, the stirring speed of the second reaction kettle is 100 r / min to 500 r / min.

[0037] In any embodiment of the present application, the stirring speed of the aging kettle is 100 r / min to 500 r / min.

[0038] In any embodiment of the present application, in step S3, the drying temperature is 200 °C to 300 °C.

[0039] In any embodiment of the present application, in step S3, the drying time is 3 h to 8 h.

[0040] In any embodiment of the present application, in step S3, the drying atmosphere is a protective gas atmosphere, and the protective gas includes nitrogen gas, inert gas or a combination thereof.

[0041] According to the third aspect of the present application, there is provided a manganese iron phosphate precursor produced by the production method of the second aspect of the present application, and the chemical formula is Fe x Mn y M 1-x-y P1-m Q m It has O4, where 0 < x < 1, preferably 0.2 ≤ x ≤ 0.5; 0 < y < 1, preferably 0.5 ≤ y ≤ 0.8; 0 ≤ 1 - x - y < 1, preferably 0 < 1 - x - y ≤ 0.05; 0 ≤ m ≤ 0.1, preferably 0 < m ≤ 0.05. M represents the doping elements of manganese sites and iron sites, preferably including one or more of Co, Mg, Zn, Ca, Ti, V, Ni, Cr. Q represents the doping elements of phosphite sites, preferably including one or more of B, S, Si, and N, and the manganese iron phosphate precursor is electrically neutral.

[0042] The manganese iron phosphate precursor provided by the present application has the advantages of small particle size, narrow particle size distribution, high crystallinity, single microcrystal, regular shape, high tap density, high stability and consistency in batch production.

[0043] In any embodiment of the present application, the manganese iron phosphate precursor has a spherical shape.

[0044] In any embodiment of the present application, the manganese iron phosphate precursor is orthorhombic, and the space group is pmnb.

[0045] In any embodiment of the present application, the volume-based particle size distribution Dv90 and Dv50 of the manganese iron phosphate precursor satisfy 1 < Dv90 / Dv50 ≤ 2, preferably 1.1 ≤ Dv90 / Dv50 ≤ 1.7.

[0046] In any embodiment of the present application, the volume-based particle size distribution Dv50 of the manganese iron phosphate precursor is 1 μm to 10 μm, preferably 2.5 μm to 6 μm.

[0047] According to the fourth aspect of the present application, a method for manufacturing lithium iron manganese phosphate is provided. At least, a lithium iron manganese phosphate precursor manufactured by the method of the second aspect of the present application or the lithium iron manganese phosphate precursor of the third aspect of the present application, a lithium source, an optional doping element N source, and an optional doping element R source are uniformly mixed at a preset ratio to obtain a mixed raw material. N represents a doping element for the lithium site, preferably including one or more of Zn, Al, Na, K, Mg, Nb, Mo, and W. R represents a doping element for the oxygen site, preferably including one or more of S, F, Cl, and Br. Step S10, and by sintering the mixed raw material obtained in step S10, lithium iron manganese phosphate is obtained. The lithium iron manganese phosphate has the chemical formula Li a N b Fe x Mn y M 1-x-y P 1-m Q m O 4-n R n where M represents a doping element for the manganese site and the iron site, preferably including one or more of Co, Mg, Zn, Ca, Ti, V, Ni, and Cr. N represents a doping element for the lithium site, preferably including one or more of Zn, Al, Na, K, Mg, Nb, Mo, and W. Q represents a doping element for the phosphorus site, preferably including one or more of B, S, Si, and N. R represents a doping element for the oxygen site, preferably including one or more of S, F, Cl, and Br. 0.9 ≦ a ≦ 1.1, 0 ≦ b ≦ 0.1, preferably 0 < b ≦ 0.05, 0 < x < 1, preferably 0.2 ≦ x ≦ 0.5, 0 < y < 1, preferably 0.5 ≦ y ≦ 0.8, 0 ≦ 1 - x - y < 1, preferably 0 < 1 - x - y ≦ 0.05, 0 ≦ m ≦ 0.1, preferably 0 < m ≦ 0.05, 0 ≦ n ≦ 0.1, preferably 0 < n ≦ 0.05, and the lithium iron manganese phosphate is electrically neutral. Step S20, and includes.

[0048] The above manufacturing method of the present application helps to obtain lithium iron manganese phosphate with a spherical shape and uniform element distribution.

[0049] In any embodiment of the present application, in step S10, a carbon source is further added to the mixed raw material, whereby lithium iron manganese phosphate coated with carbon can be produced. Further, it helps to form a complete, uniform and strong carbon coating layer by the above manufacturing method of the present application, and improves the conductivity of the obtained lithium iron manganese phosphate.

[0050] According to the fifth aspect of the present application, there is provided lithium iron manganese phosphate which is produced by the production method of the fourth aspect of the present application and can have excellent electrical and chemical properties.

[0051] According to the sixth aspect of the present application, there is provided a secondary battery including lithium iron manganese phosphate produced by the production method of the fourth aspect of the present application.

Brief Description of Drawings

[0052] To more clearly explain the technical solution means in the embodiments of the present application, the drawings necessary for the embodiments of the present application are briefly described below. It should be understood that the drawings shown below are only some embodiments of the present application, and those skilled in the art can further obtain other drawings based on the drawings without creative effort. In the drawings, the drawings are not drawn according to the actual ratio.

[0053]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Explanation of Signs

[0054] 1 First material dissolution kettle 2 Second material dissolution kettle 3 First reaction kettle 4 Second reaction kettle 5 Aging kettle 6 First supply port 7 First overflow port 8 First shut-off valve 9 First metering pump 10 Second shut-off valve 11 Second metering pump 12 Second supply port 13 Second overflow port 14 Third supply port 15 Third overflow port 16 Third shut-off valve 17 Fourth shut-off valve

Modes for Carrying Out the Invention

[0055] Hereinafter, embodiments of the continuous reaction system, iron manganese phosphate precursor, lithium iron manganese phosphate, and manufacturing method thereof of the present application, and secondary batteries will be described in detail with reference to the drawings as appropriate. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and overlapping descriptions of substantially the same structures may be omitted. This is to prevent the following description from becoming unnecessarily redundant and to facilitate understanding by those skilled in the art. Also, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0056] The "range" disclosed in this application is defined in the form of a lower limit and an upper limit. A given range is defined by selecting one lower limit and one upper limit, and the selected lower limit and upper limit define the boundaries of a specific range. A range defined in this way may or may not include the values at both ends, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 - 120 and 80 - 110 are listed for a specific parameter, ranges of 60 - 110 and 80 - 120 are also understood to be contemplated. Also, if the minimum range values 1 and 2 are listed, and the maximum range values 3, 4, and 5 are listed, ranges of 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4, and 2 - 5 are all contemplated. In this application, unless otherwise explained, the numerical range "a - b" means an abbreviated representation of any combination of real numbers between a and b, and both a and b are real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" are all listed in this specification, and "0 - 5" is only an abbreviated representation of combinations of these numerical values. Also, when a certain parameter is expressed as an integer ≧ 2, it is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0057] All embodiments and selectable embodiments of this application can, unless otherwise specified, be combined with each other to form new technical solutions, and such technical solutions should be regarded as being included in the disclosure of this application.

[0058] All technical features and selectable technical features of this application can, unless otherwise specified, be combined with each other to form new technical solutions, and such technical solutions should be regarded as being included in the disclosure of this application.

[0059] All steps of the present application can be performed in sequence or randomly, preferably in sequence, unless otherwise specified. For example, if the method includes steps S1 and S2, the method may include steps S1 and S2 performed in sequence, or steps S2 and S1 performed in sequence. For example, when it is said 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, etc.

[0060] As used in the present application, "comprising" and "including" indicate both open and closed forms unless otherwise specified. For example, the above "comprising" and "including" can indicate that other components not listed may also be included or incorporated, or that only the listed components may be included or incorporated.

[0061] In the present application, unless otherwise specified, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by either A being true (or existing) and B being false (or not existing), or A being false (or not existing) and B being true (or existing), or both A and B being true (or existing).

[0062] Unless otherwise specified, in the present application, terms such as "first", "second", "third", etc. are used to distinguish different objects and are not used to explain a specific order or a master-slave relationship.

[0063] In the present application, the terms "a plurality of" and "plural" mean two or more.

[0064] The first aspect of the embodiment of the present application provides a continuous reaction system for producing a manganese iron phosphate precursor.

[0065] As shown in FIG. 1, the continuous reaction system includes a first material dissolving kettle 1, a second material dissolving kettle 2, a first reaction kettle 3, a second reaction kettle 4, and an aging kettle 5. The first reaction kettle 3, the second reaction kettle 4, and the aging kettle 5 are connected in series in sequence via pipelines. The first material dissolving kettle 1 is used to contain the metal salt solution required for manufacturing the iron manganese phosphate precursor. The second material dissolving kettle is used to contain the oxidizing agent and the phosphorus source solution required for manufacturing the iron manganese phosphate precursor. The first reaction kettle 3 has a first supply port 6 and a first overflow port 7. The first supply port 6 of the first reaction kettle communicates with the first material dissolving kettle 1 and the second material dissolving kettle 2 via a first pipeline and a second pipeline respectively. Thereby, the first reaction kettle 3 contains the metal salt solution and the phosphorus source solution, mixes them, and then reacts to generate a first reaction solution. A first shut-off valve 8 and a first metering pump 9 are installed on the first pipeline to adjust the flow rate of the metal salt solution. A second shut-off valve 10 and a second metering pump 11 are installed on the second pipeline to adjust the flow rate of the phosphorus source solution. The second reaction kettle 4 has a second supply port 12 and a second overflow port 13. The second supply port 12 of the second reaction kettle communicates with the first overflow port 7 of the first reaction kettle via a third pipeline. Thereby, the second reaction kettle 4 contains the first reaction solution from the first reaction kettle 3 and continues to react it to generate a second reaction solution. The aging kettle 5 has a third supply port 14 and a third overflow port 15. The third supply port 14 of the aging kettle communicates with the second overflow port 13 of the second reaction kettle via a fourth pipeline. Thereby, the aging kettle 5 contains the second reaction solution from the second reaction kettle 4 and continues to react it to generate a third reaction solution. When the liquid level of the third reaction solution is higher than the third overflow port 15 of the aging kettle, the third reaction solution flows out via the third overflow port 15 of the aging kettle.

[0066] In some embodiments, stirring devices are installed in all of the first material dissolving kettle 1, the second material dissolving kettle 2, the first reaction kettle 3, the second reaction kettle 4, and the aging kettle 5.

[0067] In some embodiments, heating devices may be further installed in the first reaction kettle 3, the second reaction kettle 4, and the aging kettle 5, so as to adjust the reaction temperature of each kettle according to actual needs.

[0068] In some embodiments, a third shut-off valve 16 is further installed in the third pipeline, and a fourth shut-off valve 17 is further installed in the fourth pipeline.

[0069] When manufacturing the iron manganese phosphate precursor, the first shut-off valve 8, the second shut-off valve 10, the third shut-off valve 16, and the fourth shut-off valve 17 are all kept in an open state, thereby ensuring continuous material supply and continuous discharge, and enabling multiple kettles to react simultaneously.

[0070] The second aspect of the embodiment of the present application provides a manufacturing method for manufacturing an iron manganese phosphate precursor using the continuous reaction system of the first aspect of the embodiment of the present application. As shown in FIG. 1, the manufacturing method at least includes The first reaction kettle 3, the second reaction kettle 4, and the aging kettle 5 are connected in series in sequence through pipelines. The first reaction kettle 3 has a first supply port 6 and a first overflow port 7. The first supply port 6 of the first reaction kettle communicates with the first material dissolution kettle 1 through the first pipeline, and the first supply port 6 of the first reaction kettle communicates with the second material dissolution kettle 2 through the second pipeline. A first shut-off valve 8 and a first metering pump 9 are installed in the first pipeline, and a second shut-off valve 10 and a second metering pump 11 are installed in the second pipeline. The second reaction kettle 4 has a second supply port 12 and a second overflow port 13. The second supply port 12 of the second reaction kettle communicates with the first overflow port 7 of the first reaction kettle through the third pipeline. The aging kettle 5 includes a third supply port 14 and a third overflow port 15. The third supply port 14 of the aging kettle communicates with the second overflow port 13 of the second reaction kettle through the fourth pipeline in step S1, Add the metal salt solution required for producing the iron manganese phosphate precursor to the first material dissolving kettle 1, add the oxidizing agent and the phosphorus source solution required for producing the iron manganese phosphate precursor to the second material dissolving kettle 2, pump the metal salt solution in the first material dissolving kettle 1 into the first pipeline through the first shut-off valve 8 and the first metering pump 9, pump the phosphorus source solution in the second material dissolving kettle 2 into the second pipeline through the second shut-off valve 10 and the second metering pump 11, mix and react the metal salt solution and the phosphorus source solution in the first reaction kettle 3 to generate a first reaction solution. When the liquid level of the first reaction solution is higher than the first overflow port 7 of the first reaction kettle, the first reaction solution is automatically transported to the second reaction kettle 4 to continue the reaction to generate a second reaction solution. When the liquid level of the second reaction solution is higher than the second overflow port 13 of the second reaction kettle, the second reaction solution is automatically transported to the aging kettle 5 to continue the reaction to generate a third reaction solution. When the liquid level of the third reaction solution is higher than the third overflow port 15 of the aging kettle, the third reaction solution automatically flows out through the third overflow port 15 of the aging kettle. During the reaction process, the first material dissolving kettle 1, the second material dissolving kettle 2, the first reaction kettle 3, the second reaction kettle 4 and the aging kettle 5 are all under a protective gas atmosphere and each kettle maintains a stirring state, step S2; Step S3 of obtaining the iron manganese phosphate precursor by filtering, washing and drying the third reaction solution obtained from the third overflow port 15 of the aging kettle.

[0071] Most of the conventional reaction systems for producing iron manganese phosphate precursors adopt an intermittent production process with a single reaction kettle or a plurality of reaction kettles connected in parallel. Therefore, there is a disadvantage of low production efficiency. Moreover, when producing by the method of connecting a plurality of reaction kettles in parallel, it is necessary to switch regularly between different reaction kettles, and there are also disadvantages that the production process becomes complicated and the labor cost is high.

[0072] This application adopts the continuous reaction system shown in Figure 1 to produce the iron manganese phosphate precursor. In the continuous reaction system of this application, the first reaction kettle, the second reaction kettle and the aging kettle adopt a series communication method, thereby ensuring continuous material supply and continuous discharge, and enabling multiple kettles to react simultaneously. Therefore, the method for producing the iron manganese phosphate precursor provided by this application has the advantages of high production efficiency, high energy efficiency, simple process, easy operation and low labor cost, and is particularly suitable for large-scale industrial production.

[0073] The iron manganese phosphate precursor obtained by the conventional batch production method further has defects such as large particle size, wide particle size distribution, irregular shape and low tap density, which affect the fluidity, dispersibility and processability of the product, and significantly hinder the actual application of the iron manganese phosphate precursor in lithium iron manganese phosphate.

[0074] The method for producing the iron manganese phosphate precursor provided by this application is a continuous production method. In the continuous production process, the residence times in the first reaction kettle, the second reaction kettle and the aging kettle in the growth process of the iron manganese phosphate precursor particles are the same. Therefore, compared with the iron manganese phosphate precursor obtained by the conventional batch production method, the iron manganese phosphate precursor obtained by the continuous production method provided by this application has the advantages of small particle size, narrow particle size distribution, high crystallinity, single microcrystal, regular shape, high tap density, high stability and consistency of batch production.

[0075] The method for manufacturing the iron manganese phosphate precursor provided by this application is the hydrothermal method, and the iron manganese phosphate precursor obtained by the manufacturing method provided by this application has a regular spherical shape. The spherical shape of the iron manganese phosphate precursor can ensure that lithium ions pass through the pores on the surface of the spherical particles and penetrate into the center of the iron manganese phosphate precursor uniformly and simultaneously from all directions during the subsequent sintering process of lithium iron manganese phosphate, and is helpful for obtaining lithium iron manganese phosphate with a spherical shape and uniform distribution of each element. In addition, for the irregularly shaped iron manganese phosphate precursor manufactured by the prior art, the spherical iron manganese phosphate precursor particles obtained by the continuous manufacturing method of this application can form a complete, uniform and strong carbon coating layer during the subsequent sintering process of lithium iron manganese phosphate, improving the conductivity of the obtained lithium iron manganese phosphate.

[0076] In the method for manufacturing the iron manganese phosphate precursor provided by this application, parameters such as the flow rates of the metal salt solution and the phosphorus source solution, the residence time in each kettle during the growth process of the iron manganese phosphate precursor particles, and the reaction temperature of each kettle can all be accurately adjusted. Therefore, the manufacturing method provided by this application further has good flexibility in production.

[0077] The residence time of the iron manganese phosphate precursor particles in each kettle (the first reaction kettle, the second reaction kettle and the aging kettle) during the growth process of the iron manganese phosphate precursor shows a negative correlation with the flow rates of the metal salt solution and the phosphorus source solution, and a positive correlation with the volume of each kettle. When the flow rates of the metal salt solution and the phosphorus source solution are fast, the residence time of the iron manganese phosphate precursor particles in each kettle is short; when the flow rates of the metal salt solution and the phosphorus source solution are slow, the residence time of the iron manganese phosphate precursor particles in each kettle is long. When the volume of each kettle is small, the residence time of the iron manganese phosphate precursor particles in each kettle is short; when the volume of each kettle is large, the residence time of the iron manganese phosphate precursor particles in each kettle is long. Therefore, by adjusting the flow rates of the metal salt solution and the phosphorus source solution, and further the volume of each kettle, the adjustment of the particle size of the iron manganese phosphate precursor can be realized.

[0078] Since the reaction temperature also affects the particle size and shape of the obtained iron manganese phosphate precursor, by adjusting the reaction temperature of each kettle within different ranges, it is possible to adjust the particle size and shape of the iron manganese phosphate precursor.

[0079] Therefore, the method for producing an iron manganese phosphate precursor provided by the present application can adjust the growth rate of crystal particles and the size and shape of crystal particles, thereby meeting different production requirements and producing lithium iron manganese phosphate with different particle sizes.

[0080] In some embodiments, a complexing agent is further added to the first material dissolution kettle.

[0081] In the prior art, an iron manganese phosphate precursor is generally produced by a coprecipitation method. However, since there is a difference in the precipitation rates of different metal ions, uniform coprecipitation cannot be achieved. At the same time, there is a large difference between the molar ratio of each metal element in the obtained iron manganese phosphate precursor particles and the molar ratio of each metal element in the raw materials, which affects the performance and consistency of the product. In addition, the iron manganese phosphate precursor particles produced by the coprecipitation method of the prior art are generally irregular sheet-like or block-like, so their tap density is low, which affects the fluidity, dispersibility and processability of the product, and greatly hinders the actual application of the iron manganese phosphate precursor in lithium iron manganese phosphate.

[0082] The method for producing the iron manganese phosphate precursor provided by this application is a hydrothermal method. In the production method provided by this application, a complexing agent is further added to the first material dissolution kettle. The complexing agent can complex metal ions and achieve the purpose of controlling free metal ions, thereby improving the conversion efficiency of metal ions, reducing the difference in the reaction rates of different metal ions in the reaction solution, and realizing uniform deposition and crystallization. Therefore, when a complexing agent is further added to the first material dissolution kettle, according to the production method of this application, spherical iron manganese phosphate precursor particles with high purity and uniform distribution of metal elements can be obtained. It has a higher tap density. At the same time, the difference between the molar ratio of each metal element in the spherical iron manganese phosphate precursor particles obtained by the production method of this application and the molar ratio of each metal element in the raw material is small, thereby enabling accurate control of the metal element content.

[0083] Preferably, the complexing agent contains one or more of aminocarboxylates, hydroxycarboxylates, and organic phosphonic acids. More preferably, the complexing agent contains one or more of sodium nitrilotriacetate, disodium ethylenediaminetetraacetate, sodium gluconate, and sodium citrate.

[0084] Preferably, the mass concentration of the complexing agent is 10 wt% or less based on the total mass of the metal salt solution, and more preferably 1 wt% - 10 wt%.

[0085] In some embodiments, a surfactant is further added to the first material dissolution kettle, which helps to better adjust the shape of the iron manganese phosphate precursor particles.

[0086] Preferably, the surfactant contains one or more of cetyltrimethylammonium bromide, sodium dodecylsulfonate, and polyvinylpyrrolidone.

[0087] Preferably, the mass concentration of the surfactant is 5 wt% or less based on the total mass of the metal salt solution, preferably 1 wt% - 5 wt%.

[0088] In some embodiments, the reaction temperature of the first reaction kettle is lower than that of the second reaction kettle, and the reaction temperature of the aging kettle is lower than that of the second reaction kettle.

[0089] In the method for producing the iron manganese phosphate precursor provided by the present application, the first reaction kettle, the second reaction kettle and the aging kettle adopt a series communication mode, and the reaction temperatures of the first reaction kettle and the aging kettle are set lower than that of the second reaction kettle, so that different main functions can be imparted to each kettle in the continuous reaction system. Since the reaction temperature of the first reaction kettle is low, in the first reaction kettle, preliminary mixing of the metal salt solution and the phosphorus source solution and rapid preliminary nucleation can be realized. At this time, metal ions and phosphate ions (PO4 3- ) tend to form a large number of crystal nuclei, which is beneficial to better crystallization and control of particle size distribution in the subsequent second reaction kettle. Since the reaction temperature of the second reaction kettle is high, after the reaction solution flows from the first reaction kettle to the second reaction kettle, the high reaction temperature can supply sufficient energy to promote the growth and crystallization of crystal nuclei, and on the premise of avoiding the condensation growth of crystal nuclei, the improvement of the crystallinity of crystal nuclei can be realized. The reaction temperature of the aging kettle is lower than that of the second reaction kettle, so that when the reaction solution flows from the second reaction kettle to the aging kettle, it can play a role in cooling the reaction solution. The raw materials not involved in the reaction in the reaction solution can continue to crystallize on the surface of the formed crystal particles, realizing the continuous growth of crystal particles, increasing the size of crystal particles and making the particle size distribution of crystal particles narrower.

[0090] Therefore, the particle size of the iron manganese phosphate precursor obtained by adjusting the reaction temperature of each kettle can be adjusted, which is helpful to obtain iron manganese phosphate precursor particles with a narrow particle size distribution, high crystallinity, single microcrystals, regular shape and high tap density.

[0091] In some embodiments, preferably, the reaction temperature of the first reaction kettle is 70°C to 90°C.

[0092] In some embodiments, preferably, the reaction temperature of the second reaction kettle is 150°C to 250°C.

[0093] In some embodiments, preferably, the reaction temperature of the aging kettle is 20°C to 30°C.

[0094] In some embodiments, the flow rate in the first pipeline of the metal salt solution (or the pump speed of the first metering pump) is 0.2 L / min to 2 L / min, preferably 0.25 L / min to 1 L / min.

[0095] In some embodiments, the flow rate in the second pipeline of the phosphorus source solution (or the pump speed of the second metering pump) is 0.2 L / min to 2 L / min, preferably 0.25 L / min to 1 L / min.

[0096] In some embodiments, the flow rates of the metal salt solution and the phosphorus source solution are the same (that is, the pump speeds of the first metering pump and the second metering pump are the same), which helps to improve the consistency of the manganese iron phosphate precursor particles obtained.

[0097] In some embodiments, the residence time in the first reaction kettle during the growth process of the manganese iron phosphate precursor is 1 h to 4 h.

[0098] In some embodiments, the residence time in the second reaction kettle during the growth process of the manganese iron phosphate precursor is 1 h to 16 h, preferably 4 h to 16 h.

[0099] In some embodiments, the residence time in the aging kettle during the growth process of the manganese iron phosphate precursor is 1 h to 48 h, preferably 12 h to 48 h.

[0100] In some embodiments, the volume of the first reaction kettle is less than or equal to the volume of the second reaction kettle. As a result, the residence time in the second reaction kettle during the growth process of the iron manganese phosphate precursor is long, which helps the obtained iron manganese phosphate precursor particles to have a higher crystallinity. Preferably, the ratio of the volume of the first reaction kettle to the volume of the second reaction kettle is 1:(1 - 4), and more preferably 1:(2 - 4).

[0101] In some embodiments, the volume of the first reaction kettle is less than or equal to the volume of the aging kettle. As a result, the residence time in the aging kettle during the growth process of the iron manganese phosphate precursor is long, which helps the obtained iron manganese phosphate precursor to have a larger particle size. Preferably, the ratio of the volume of the first reaction kettle to the volume of the aging kettle is 1:(1 - 12), and more preferably 1:(4 - 12).

[0102] In some embodiments, the volume of the second reaction kettle is less than or equal to the volume of the aging kettle. As a result, the residence time in the aging kettle during the growth process of the iron manganese phosphate precursor is long, which helps the obtained iron manganese phosphate precursor to have a larger particle size. Preferably, the ratio of the volume of the second reaction kettle to the volume of the aging kettle is 1:(1 - 3), and more preferably 1:(2 - 3).

[0103] In some embodiments, in step S3, preferably, the drying temperature is 200°C to 300°C.

[0104] In some embodiments, in step S3, preferably, the drying time is 3h to 8h.

[0105] In some embodiments, in step S3, the drying may be performed in a dryer, and the drying atmosphere may be a protective gas atmosphere. The protective gas includes nitrogen gas, inert gas or a combination thereof. Preferably, the inert gas includes helium gas, argon gas or a combination thereof.

[0106] In some embodiments, the metal salts required for manufacturing the iron manganese phosphate precursor include a water-soluble iron salt, a water-soluble manganese salt, and preferably a salt of a water-soluble doping element M, where M represents a doping element for the manganese site and the iron site, and preferably includes one or more of Co, Mg, Zn, Ca, Ti, V, Ni, and Cr.

[0107] The water-soluble iron salt may be a compound containing various iron ions (such as divalent iron ions and trivalent iron ions) that are conventionally soluble in water. Preferably, the water-soluble iron salt includes one or more of ferrous chloride, ferrous nitrate, ferrous sulfate, ferrous acetate, ferric chloride, ferric nitrate, ferric sulfate, and ferric acetate.

[0108] The water-soluble manganese salt may be a compound containing various manganese ions (such as divalent manganese ions) that are conventionally soluble in water. Preferably, the water-soluble manganese salt includes one or more of manganese chloride, manganese nitrate, manganese sulfate, and manganese acetate.

[0109] The salt of the water-soluble doping element M may be various M ion-containing compounds that are conventionally soluble in water. Preferably, the salt of the water-soluble doping element M includes one or more of the hydrochloride, nitrate, sulfate, and acetate salts of the doping element M.

[0110] In some embodiments, the phosphorus source required for manufacturing the iron manganese phosphate precursor includes one or more of phosphoric acid and water-soluble phosphates. Preferably, the water-soluble phosphates include one or more of trisodium phosphate, tripotassium phosphate, ammonium hydrogen phosphate, diammonium hydrogen phosphate, and ammonium phosphate.

[0111] In some embodiments, the phosphorus source required for manufacturing the iron manganese phosphate precursor may further contain a water-soluble doping element Q source, where Q represents a doping element of phosphosite and preferably includes one or more of B, S, Si, and N. In some embodiments, preferably, the doping element Q source includes one or more of sulfates, borates, nitrates, and silicates of the doping element Q.

[0112] In some embodiments, the metal salt solution is an aqueous metal salt solution, for example, obtained by uniformly mixing a metal salt required for manufacturing the iron manganese phosphate precursor and deionized water.

[0113] In some embodiments, the phosphorus source solution is an aqueous phosphorus source solution, for example, obtained by uniformly mixing an oxidizing agent, a phosphorus source, and deionized water.

[0114] In some embodiments, the oxidizing agent includes one or more of hydrogen peroxide solution, nitric acid, sodium hypochlorite, potassium hypochlorite, sodium chlorate, and potassium chlorate, and preferably is hydrogen peroxide solution.

[0115] In some embodiments, the concentration of the metal salt solution is 0.5 mol / L to 2 mol / L, and preferably is 0.5 mol / L to 1 mol / L.

[0116] In some embodiments, the concentration of the phosphorus source solution is 0.5 mol / L to 2 mol / L, and preferably is 0.5 mol / L to 1 mol / L.

[0117] The addition amount of the phosphorus source may be excessive relative to the metal salt. In some embodiments, the molar ratio of the metal salt to the phosphorus source is 1:1 to 1:3.

[0118] The addition amount of the oxidizing agent may be excessive relative to the metal salt. In some embodiments, the molar ratio of the metal salt to the oxidizing agent is 1:(0.1 to 1.2), and preferably is 1:(0.5 to 0.6).

[0119] During the reaction process, the first material dissolution kettle, the second material dissolution kettle, the first reaction kettle, the second reaction kettle, and the aging kettle all maintain a stirring state. In some embodiments, the stirring speed of the first material dissolution kettle is 100 r / min to 500 r / min. In some embodiments, the stirring speed of the second material dissolution kettle is 100 r / min to 500 r / min. In some embodiments, the stirring speed of the first reaction kettle is 100 r / min to 500 r / min. In some embodiments, the stirring speed of the second reaction kettle is 100 r / min to 500 r / min. In some embodiments, the stirring speed of the aging kettle is 100 r / min to 500 r / min.

[0120] During the reaction process, protective gas is introduced into the first material dissolution kettle, the second material dissolution kettle, the first reaction kettle, the second reaction kettle, and the aging kettle. In some embodiments, the protective gas includes nitrogen gas, inert gas, or a combination thereof. Preferably, the inert gas includes helium gas, argon gas, or a combination thereof.

[0121] In the method for producing the manganese iron phosphate precursor provided by the present application, unless otherwise specified, each raw material may be directly purchased.

[0122] According to the third aspect of the embodiment of the present application, a manganese iron phosphate precursor produced by the production method of the second aspect of the embodiment of the present application is provided, and the manganese iron phosphate precursor has the chemical formula Fe x Mn y M 1-x-y P 1-m Q m O4, where 0 < x < 1, 0 < y < 1, 0 ≤ 1 - x - y < 1, 0 ≤ m ≤ 0.1, M represents a doping element of the manganese site and the iron site, preferably including one or more of Co, Mg, Zn, Ca, Ti, V, Ni, Cr, Q represents a doping element of the phosphorus site, preferably including one or more of B, S, Si, and N, and the manganese iron phosphate precursor is electrically neutral.

[0123] The manganese iron phosphate precursor provided by the present application is produced by the method of the second aspect of the embodiments of the present application. Therefore, it has the advantages of small particle size, narrow particle size distribution, high crystallinity, single microcrystal, regular shape, high tap density, and high stability and consistency in batch production.

[0124] In some embodiments, the manganese iron phosphate precursor has a spherical shape.

[0125] In some embodiments, the manganese iron phosphate precursor is orthorhombic and the space group is pmnb.

[0126] In some embodiments, the volume-based particle size distributions Dv90 and Dv50 of the manganese iron phosphate precursor satisfy 1 < Dv90 / Dv50 ≤ 2, and preferably, 1.1 ≤ Dv90 / Dv50 ≤ 1.7.

[0127] In some embodiments, the volume-based particle size distribution Dv50 of the manganese iron phosphate precursor is 1 μm to 10 μm, and preferably, 2.5 μm to 6 μm.

[0128] In some embodiments, 0.2 ≤ x ≤ 0.5.

[0129] In some embodiments, 0.5 ≤ y ≤ 0.8.

[0130] In some embodiments, 1 - x - y = 0, and in another embodiment, 0 < 1 - x - y ≤ 0.05.

[0131] In some embodiments, m = 0, and in another embodiment, 0 < m ≤ 0.05.

[0132] According to the fourth aspect of the embodiment of the present application, a method for manufacturing lithium iron manganese phosphate is provided. At least, a lithium iron manganese phosphate precursor manufactured by the method of the second aspect of the embodiment of the present application or a lithium iron manganese phosphate precursor of the third aspect of the embodiment of the present application, a lithium source, an optional doping element N source, and an optional doping element R source are uniformly mixed at a preset ratio to obtain a mixed raw material. N represents a doping element for lithium sites, preferably including one or more of Zn, Al, Na, K, Mg, Nb, Mo, and W. R represents a doping element for oxygen sites, preferably including one or more of S, F, Cl, and Br. Step S10; by sintering the mixed raw material obtained in step S10, lithium iron manganese phosphate is obtained. The lithium iron manganese phosphate has the chemical formula Li a N b Fe x Mn y M 1-x-y P 1-m Q m O 4-n R n wherein M represents a doping element for manganese sites and iron sites, preferably including one or more of Co, Mg, Zn, Ca, Ti, V, Ni, and Cr. N represents a doping element for lithium sites, preferably including one or more of Zn, Al, Na, K, Mg, Nb, Mo, and W. Q represents a doping element for phosphorus sites, preferably including one or more of B, S, Si, and N. R represents a doping element for oxygen sites, preferably including one or more of S, F, Cl, and Br. 0.9 ≦ a ≦ 1.1, 0 ≦ b ≦ 0.1, preferably 0 < b ≦ 0.05, 0 < x < 1, preferably 0.2 ≦ x ≦ 0.5, 0 < y < 1, preferably 0.5 ≦ y ≦ 0.8, 0 ≦ 1 - x - y < 1, preferably 0 < 1 - x - y ≦ 0.05, 0 ≦ m ≦ 0.1, preferably 0 < m ≦ 0.05, 0 ≦ n ≦ 0.1, preferably 0 < n ≦ 0.05, and the lithium iron manganese phosphate is electrically neutral. Step S20; including.

[0133] When manufacturing lithium iron manganese phosphate using the above-mentioned manganese iron phosphate precursor of the present application, in the process of sintering treatment, lithium ions can pass through the pores on the surface of the spherical manganese iron phosphate precursor particles and penetrate uniformly and simultaneously into the center of the manganese iron phosphate precursor from all directions, which helps to obtain lithium iron manganese phosphate with a spherical shape and uniform distribution of each element. Therefore, the lithium iron manganese phosphate obtained by the manufacturing method of the present application has excellent electrical and chemical properties.

[0134] In some embodiments, the lithium source may be a lithium-containing compound known in the art used for manufacturing the cathode active material of lithium iron manganese phosphate. For example, the lithium source may include one or more of Li2CO3, LiOH, Li3PO4, and LiH2PO4.

[0135] In some embodiments, the doping element N source includes one or more of the hydrochloride, nitrate, sulfate, and acetate salts of the doping element N.

[0136] In some embodiments, the doping element R source includes one or more of the simple substance of the doping element R and ammonium salts.

[0137] By selecting the above doping element sources, the uniformity of the distribution of the above doping elements can be improved, and the electrical and chemical properties of lithium iron manganese phosphate can be improved.

[0138] In some embodiments, in step S10, a carbon source may be further added to the mixed raw materials, whereby lithium iron manganese phosphate coated with carbon can be manufactured. When manufacturing lithium iron manganese phosphate using the above-mentioned manganese iron phosphate precursor of the present application, a complete, uniform, and strong carbon coating layer can be formed on the surface of lithium iron manganese phosphate, improving the conductivity of the obtained lithium iron manganese phosphate.

[0139] In some embodiments, the carbon source includes one or more of an organic carbon source and an inorganic carbon source, preferably including one or more combinations of glucose, sucrose, starch, fructose, polyvinyl alcohol, polyethylene glycol, and citric acid.

[0140] In the above manufacturing method, the addition amounts of the doping element N and the R source respectively depend on the target doping amount, and the addition amount of the lithium source conforms to the stoichiometric ratio of lithium manganese iron phosphate. In some embodiments, the addition amount of the lithium source may be slightly excessive, for example, it may be 100% - 110% of the theoretical mass of the lithium source. The theoretical mass of the lithium source is the mass of the lithium source calculated based on the stoichiometric ratio of lithium manganese iron phosphate.

[0141] In the above manufacturing method, unless otherwise specified, each raw material may be directly purchased.

[0142] According to the fifth aspect of the embodiments of the present application, lithium manganese iron phosphate manufactured by the manufacturing method of the fourth aspect of the embodiments of the present application is provided.

[0143] The lithium manganese iron phosphate has the chemical formula Li a N b Fe x Mn y M 1-x-y P 1-m Q m O 4-n R nhaving, where M represents doping elements for manganese sites and iron sites, preferably including one or more of Co, Mg, Zn, Ca, Ti, V, Ni, Cr; N represents doping elements for lithium sites, preferably including one or more of Zn, Al, Na, K, Mg, Nb, Mo, and W; Q represents doping elements for phosphorus sites, preferably including one or more of B, S, Si, and N; R represents doping elements for oxygen sites, preferably including one or more of S, F, Cl, and Br; 0.9 ≦ a ≦ 1.1, 0 ≦ b ≦ 0.1, preferably 0 < b ≦ 0.05, 0 < x < 1, preferably 0.2 ≦ x ≦ 0.5, 0 < y < 1, preferably 0.5 ≦ y ≦ 0.8, 0 ≦ 1 - x - y < 1, preferably 0 < 1 - x - y ≦ 0.05, 0 ≦ m ≦ 0.1, preferably 0 < m ≦ 0.05, 0 ≦ n ≦ 0.1, preferably 0 < n ≦ 0.05, and the lithium iron manganese phosphate is electrically neutral.

[0144] In some embodiments, the surface of the lithium iron manganese phosphate is coated with carbon, thereby improving the conductivity of the lithium iron manganese phosphate.

[0145] According to the sixth aspect of the embodiments of the present application, a secondary battery including lithium iron manganese phosphate manufactured by the manufacturing method of the fourth aspect of the embodiments of the present application is provided. The lithium iron manganese phosphate can be applied as a positive electrode active material in a secondary battery and is helpful for improving the electrical and chemical properties of the secondary battery.

[0146] Example The following examples describe the content disclosed in this application in more detail. However, since various modifications and changes within the scope of the content disclosed in this application are obvious to those skilled in the art, these examples are merely illustrative. Unless otherwise specified, all parts, percentages, and ratios reported in the following examples are based on mass, and all reagents used in the examples are either commercially available or synthesized according to conventional methods, and can be used directly without treatment. All equipment used in the examples is commercially available.

[0147] Example 1 Adopt the continuous reaction system shown in Figure 1 to produce the iron manganese phosphate precursor.

[0148] Ferrous chloride, a water-soluble divalent manganese salt, ferrous chloride, a water-soluble divalent iron salt, and deionized water are added to the first material dissolution kettle to prepare a metal salt solution with a concentration of 1 mol / L. In the adjusted metal salt solution, the molar ratio of divalent manganese ions to divalent iron ions is 5:5. Hydrogen peroxide solution as an oxidant, phosphoric acid as a phosphorus source, and deionized water are added to the second material dissolution kettle to prepare a phosphorus source solution with a concentration of 1 mol / L, and the molar ratio of hydrogen peroxide solution to metal salt is controlled to be (0.5 - 0.6):1.

[0149] As shown in Figure 1, nitrogen gas is introduced into the first material dissolution kettle, the second material dissolution kettle, the first reaction kettle, the second reaction kettle, and the aging kettle, and the stirring speed of each kettle in the reaction process is 200 r / min. The reaction temperature of the first reaction kettle is controlled at 90 °C, the reaction temperature of the second reaction kettle is controlled at 160 °C, and the reaction temperature of the aging kettle is controlled at 25 °C.

[0150] The metal salt solution and the phosphorus source solution are continuously pumped from the first material dissolution kettle and the second material dissolution kettle to the first reaction kettle through a shut-off valve and a metering pump, respectively, mixed and reacted to produce the first reaction solution, and the flow rates of the metal salt solution and the phosphorus source solution are both 0.5 L / min.

[0151] After reacting for 2 h, when the liquid level of the first reaction solution becomes higher than the first overflow port, it automatically flows out from the first overflow port into the second reaction kettle to continue the reaction and generate the second reaction solution.

[0152] After the reaction continues for 8 h, when the liquid level of the second reaction solution becomes higher than the second overflow port, it automatically flows out from the second overflow port into the aging kettle to continue the reaction and generate the third reaction solution.

[0153] After the reaction continues for 24 h, when the liquid level of the third reaction solution becomes higher than the third overflow port, it automatically flows out from the third overflow port.

[0154] After filtering and washing the obtained third reaction solution with a filter press, it is transferred to a dryer and dried at 200 °C for 6 h under a nitrogen gas atmosphere to remove the crystal water, and finally a manganese iron phosphate precursor is obtained.

[0155] Example 2 Adopt the continuous reaction system shown in Fig. 1 to manufacture a manganese iron phosphate precursor.

[0156] Manganous nitrate as a water-soluble divalent manganese salt, ferrous nitrate as a water-soluble divalent iron salt, sodium nitrilotriacetate as a complexing agent, and deionized water are added to the first material dissolving kettle to prepare a metal salt solution with a concentration of 0.5 mol / L. In the prepared metal salt solution, the molar ratio of divalent manganese ions to divalent iron ions is 6:4, and the mass concentration of the complexing agent is 1 wt%. Hydrogen peroxide solution as an oxidizing agent, phosphoric acid as a phosphorus source, and deionized water are added to the second material dissolving kettle to prepare a phosphorus source solution with a concentration of 0.5 mol / L, and the molar ratio of hydrogen peroxide solution to the metal salt is controlled to be (0.5 - 0.6):1.

[0157] As shown in Fig. 1, nitrogen gas is introduced into the first material dissolving kettle, the second material dissolving kettle, the first reaction kettle, the second reaction kettle, and the aging kettle, and the stirring speed of each kettle in the reaction process is 250 r / min. The reaction temperature of the first reaction kettle is controlled at 80 °C, the reaction temperature of the second reaction kettle is controlled at 180 °C, and the reaction temperature of the aging kettle is controlled at 25 °C.

[0158] The metal salt solution and the phosphorus source solution are continuously transported from the first material dissolving kettle and the second material dissolving kettle to the first reaction kettle respectively through a shut-off valve and a metering pump, and they are mixed and reacted to produce a first reaction solution. The flow rates of both the metal salt solution and the phosphorus source solution are 0.25 L / min.

[0159] After reacting for 4 h, when the liquid level of the first reaction solution becomes higher than the first overflow port, it automatically flows out from the first overflow port into the second reaction kettle to continue the reaction and produce a second reaction solution.

[0160] After the reaction continues for 16 h, when the liquid level of the second reaction solution becomes higher than the second overflow port, it automatically flows out from the second overflow port into the aging kettle to continue the reaction and produce a third reaction solution.

[0161] After the reaction continues for 48 h, when the liquid level of the third reaction solution becomes higher than the third overflow port, it automatically flows out from the third overflow port.

[0162] The obtained third reaction solution is filtered and washed with a filter press, then transferred to a dryer and dried at 200 °C for 6 h under a nitrogen gas atmosphere to remove the crystal water, and finally a manganese iron phosphate precursor is obtained.

[0163] Example 3 Adopt the continuous reaction system shown in Figure 1 to manufacture a manganese iron phosphate precursor.

[0164] Add manganese nitrate as a water-soluble divalent manganese salt, ferrous sulfate as a water-soluble divalent iron salt, chromous sulfate as a water-soluble divalent iron chromium salt, disodium ethylenediaminetetraacetate as a complexing agent, and deionized water into a first material dissolving kettle to prepare a metal salt solution with a concentration of 1 mol / L. In the prepared metal salt solution, the molar ratio of divalent manganese ions, divalent iron ions, and divalent chromium ions is 6.9:3:0.1, and the mass concentration of the complexing agent is 5 wt%. Add hydrogen peroxide solution as an oxidizing agent, trisodium phosphate as a phosphorus source, and deionized water into a second material dissolving kettle to prepare a phosphorus source solution with a concentration of 1 mol / L, and control the molar ratio of hydrogen peroxide solution to the metal salt to be (0.5 - 0.6):1.

[0165] As shown in Figure 1, introduce nitrogen gas into the first material dissolving kettle, the second material dissolving kettle, the first reaction kettle, the second reaction kettle, and the aging kettle, and the stirring speed of each kettle in the reaction process is 150 r / min. Control the reaction temperature of the first reaction kettle to 90 °C, the reaction temperature of the second reaction kettle to 160 °C, and the reaction temperature of the aging kettle to 25 °C.

[0166] Transport the metal salt solution and the phosphorus source solution continuously from the first material dissolving kettle and the second material dissolving kettle to the first reaction kettle through a shut-off valve and a metering pump, mix them and react to generate a first reaction solution, and the flow rates of the metal salt solution and the phosphorus source solution are both 1 L / min.

[0167] After reacting for 1 h, when the liquid level of the first reaction solution is higher than the first overflow port, it automatically flows out from the first overflow port into the second reaction kettle to continue the reaction and generate a second reaction solution.

[0168] After the reaction continues for 4 h, when the liquid level of the second reaction solution is higher than the second overflow port, it automatically flows out from the second overflow port into the aging kettle to continue the reaction and generate a third reaction solution.

[0169] After the reaction continues for 12 h, when the liquid level of the third reaction solution is higher than the third overflow port, it automatically flows out from the third overflow port.

[0170] The obtained third reaction solution was filtered and washed with a filter press, then transferred to a dryer and dried at 200 °C for 6 h under a nitrogen gas atmosphere to remove the crystal water, and finally a manganese iron phosphate precursor was obtained.

[0171] Comparative Example 1 Manganous nitrate as a water-soluble divalent manganese salt, ferrous nitrate as a water-soluble divalent iron salt and deionized water were added to a first material dissolving kettle to prepare a metal salt solution with a concentration of 0.5 mol / L. In the prepared metal salt solution, the molar ratio of divalent manganese ions to divalent iron ions is 6:4. Hydrogen peroxide as an oxidizing agent, phosphoric acid as a phosphorus source and deionized water were added to a second material dissolving kettle to prepare a phosphorus source solution with a concentration of 0.5 mol / L, and the molar ratio of hydrogen peroxide to the metal salt was controlled to be (0.5 - 0.6):1.

[0172] The metal salt solution and the phosphorus source solution were simultaneously pumped into a reaction kettle. The pump speed of the metering pump was 0.25 L / min. Nitrogen gas was introduced into the reaction kettle, and it was started and quickly stirred. The stirring speed was 250 r / min. The temperature of the reaction kettle was controlled at 180 °C, and the reaction time was 20 h. After the reaction was completed, it was naturally cooled from 180 °C to room temperature to obtain a paste. The obtained paste was discharged from the discharge port of the reaction kettle, filtered and washed with a filter press, then transferred to a dryer and dried at 200 °C for 6 h under a nitrogen gas atmosphere to remove the crystal water, and finally a manganese iron phosphate precursor was obtained.

[0173] Comparative Example 2 Manganous nitrate as a water-soluble divalent manganese salt, ferrous nitrate as a water-soluble divalent iron salt, sodium nitrilotriacetate as a complexing agent and deionized water were added to a first material dissolving kettle to prepare a metal salt solution with a concentration of 0.5 mol / L. In the prepared metal salt solution, the molar ratio of divalent manganese ions to divalent iron ions is 6:4, and the mass concentration of the complexing agent is 1 wt%. Hydrogen peroxide as an oxidizing agent, phosphoric acid as a phosphorus source and deionized water were added to a second material dissolving kettle to prepare a phosphorus source solution with a concentration of 0.5 mol / L, and the molar ratio of hydrogen peroxide to the metal salt was controlled to be (0.5 - 0.6):1.

[0174] Pump the metal salt solution and the phosphorus source solution into the reaction kettle simultaneously. The pump speed of the metering pump is 0.25 L / min. Introduce nitrogen gas into the reaction kettle, start it and stir rapidly. The stirring speed is 250 r / min. Control the temperature of the reaction kettle at 180 °C, and the reaction time is 20 h. After the reaction is completed, cool it naturally from 180 °C to room temperature to obtain a paste. Discharge the obtained paste from the discharge port of the reaction kettle, filter and wash it with a filter press, then transfer it to a dryer and dry it at 200 °C for 6 h under a nitrogen gas atmosphere to remove the crystal water, and finally obtain a manganese iron phosphate precursor.

[0175] Test section (1) Particle size measurement The volume-based particle size distribution of the manganese iron phosphate precursor prepared above was measured using a Malvern Master Size 3000 laser particle size distribution analyzer. Dv50 and Dv90 are the corresponding particle sizes when the cumulative volume distribution percentage of the material reaches 50% and 90%. Refer to GB / T 19077-2016 as the basis for the measurement.

[0176] (2) Measurement of Mn / Fe molar ratio Using a Plasma 3000 type inductively coupled plasma optical emission spectrometer, measure the contents of manganese and iron elements in the manganese iron phosphate precursor prepared above by the ICP-OES method, and calculate their molar ratio.

[0177]

Table 1

[0178] Figure 2 is an X-ray diffraction spectrum (XRD) image of the iron manganese phosphate precursor manufactured in Example 1. Figure 3 is a scanning electron microscope (SEM) image of the iron manganese phosphate precursor manufactured in Example 1. The magnification of Figure 3(a) is 1000 times, and the magnification of Figure 3(b) is 20000 times. Figure 4 is a scanning electron microscope (SEM) image of the iron manganese phosphate precursor manufactured in Comparative Example 1 at a magnification of 1000 times. Figure 5 is a scanning electron microscope (SEM) image of the iron manganese phosphate precursor manufactured in Comparative Example 2 at a magnification of 1000 times.

[0179] As can be seen from a comprehensive consideration of the measurement results in Table 1 and Figures 2 to 3, the iron manganese phosphate precursor manufactured by the continuous manufacturing method provided in the present application has the advantages of small particle size, narrow particle size distribution, high crystallinity, single microcrystal, and regular shape.

[0180] As can be seen from a comprehensive consideration of the measurement results in Table 1 and Figures 4 to 5, the iron manganese phosphate precursor manufactured by the conventional batch manufacturing method has a large particle size, a wide particle size distribution, and low regularity of shape at the same time.

[0181] As can be seen from a comprehensive consideration of the measurement results of Example 2, Comparative Example 1, and Comparative Example 2, the difference between the molar ratio of Mn / Fe in the iron manganese phosphate precursor particles manufactured by the continuous manufacturing method provided in the present application and the molar ratio of Mn / Fe in the metal salt solution is smaller, and thus accurate control of the contents of the manganese element and the iron element can be realized.

[0182] As can be further seen from a comprehensive consideration of the measurement results of Example 2, Comparative Example 1, and Comparative Example 2, the complexing agent helps to more accurately control the contents of the manganese element and the iron element in the manufactured iron manganese phosphate precursor particles.

[0183] Note that this application is not limited to the above embodiments. The above embodiments are merely examples, and any embodiments having a configuration that is substantially the same as the technical idea and exhibiting the same operational effects within the scope of the technical solution of this application are included in the technical scope of this application. Also, within the scope not departing from the gist of this application, various modifications that can be conceived by those skilled in the art added to the embodiments, as well as other forms constructed by combining some of the components in the embodiments, are also included in the scope of this application.

Claims

1. A continuous reaction system for manufacturing a manganese iron phosphate precursor, comprising: a first material dissolving kettle, a second material dissolving kettle, a first reaction kettle, a second reaction kettle, and an aging kettle, wherein the first reaction kettle, the second reaction kettle, and the aging kettle are connected in series in sequence via pipelines; the first material dissolving kettle is used for containing a metal salt solution required for manufacturing the manganese iron phosphate precursor, and the second material dissolving kettle is used for containing an oxidizing agent and a phosphorus source solution required for manufacturing the manganese iron phosphate precursor; the first reaction kettle has a first supply port and a first overflow port. The first supply port of the first reaction kettle communicates with the first material dissolving kettle and the second material dissolving kettle respectively via a first pipeline and a second pipeline. Thereby, the first reaction kettle contains and mixes the metal salt solution and the phosphorus source solution and then reacts them to generate a first reaction solution. A first shut-off valve and a first metering pump are installed on the first pipeline to adjust the flow rate of the metal salt solution, and a second shut-off valve and a second metering pump are installed on the second pipeline to adjust the flow rate of the phosphorus source solution; the second reaction kettle has a second supply port and a second overflow port. The second supply port of the second reaction kettle communicates with the first overflow port of the first reaction kettle via a third pipeline. Thereby, the second reaction kettle contains the first reaction solution from the first reaction kettle and continuously reacts it to generate a second reaction solution; the aging kettle includes a third supply port and a third overflow port. The third supply port of the aging kettle communicates with the second overflow port of the second reaction kettle via a fourth pipeline. Thereby, the aging kettle contains the second reaction solution from the second reaction kettle and continuously reacts it to generate a third reaction solution; A continuous reaction system, wherein when the liquid level of the third reaction solution is higher than the third overflow port of the aging kettle, the third reaction solution flows out via the third overflow port of the aging kettle.

2. At least, The first reaction kettle, the second reaction kettle and the aging kettle are connected in series in sequence through pipelines. The first reaction kettle has a first supply port and a first overflow port. The first supply port of the first reaction kettle communicates with the first material dissolution kettle through a first pipeline, and the first supply port of the first reaction kettle communicates with the second material dissolution kettle through a second pipeline. A first shut-off valve and a first metering pump are installed in the first pipeline, and a second shut-off valve and a second metering pump are installed in the second pipeline. The second reaction kettle has a second supply port and a second overflow port. The second supply port of the second reaction kettle communicates with the first overflow port of the first reaction kettle through a third pipeline. The aging kettle includes a third supply port and a third overflow port. The third supply port of the aging kettle communicates with the second overflow port of the second reaction kettle through a fourth pipeline. Step S1 Add the metal salt solution required for manufacturing the iron manganese phosphate precursor to the first material dissolution kettle, add the oxidizing agent and the phosphorus source solution required for manufacturing the iron manganese phosphate precursor to the second material dissolution kettle. Pump the metal salt solution in the first material dissolution kettle into the first pipeline through the first shut-off valve and the first metering pump, and pump the phosphorus source solution in the second material dissolution kettle into the second pipeline through the second shut-off valve and the second metering pump, so as to mix and react the metal salt solution and the phosphorus source solution in the first reaction kettle to generate a first reaction solution. When the liquid level of the first reaction solution is higher than the first overflow port of the first reaction kettle, the first reaction solution is automatically transported to the second reaction kettle to continue the reaction to generate a second reaction solution. When the liquid level of the second reaction solution is higher than the second overflow port of the second reaction kettle, the second reaction solution is automatically transported to the aging kettle to continue the reaction to generate a third reaction solution. When the liquid level of the third reaction solution is higher than the third overflow port of the aging kettle, the third reaction solution automatically flows out through the third overflow port of the aging kettle. During the reaction process, the first material dissolution kettle, the second material dissolution kettle, the first reaction kettle, the second reaction kettle and the aging kettle are all under a protective gas atmosphere and each kettle maintains a stirring state. Step S2 Step S3 of obtaining the iron manganese phosphate precursor by filtering, washing and drying the third reaction solution obtained from the third overflow port of the aging kettle. A method for manufacturing an iron manganese phosphate precursor, including this step.

3. The manufacturing method according to claim 2, wherein a complexing agent is further added to the first material dissolution kettle. **Claim 4**: The manufacturing method according to claim 3, wherein the complexing agent contains one or more of aminocarboxylates, hydroxycarboxylates, and organic phosphonates. **Claim 5** The manufacturing method according to claim 2, wherein a surfactant is further added to the first material dissolving kettle. **Claim 6**: The manufacturing method according to claim 5, wherein the surfactant contains one or more of cetyltrimethylammonium bromide, sodium dodecyl sulfonate, and polyvinylpyrrolidone. **Claim 7** The manufacturing method according to claim 2, wherein the reaction temperature of the first reaction kettle is lower than that of the second reaction kettle, and the reaction temperature of the aging kettle is lower than that of the second reaction kettle. **Claim 8** The flow rate of the metal salt solution in the first pipeline is 0.2 L / min to 2 L / min, and / or The flow rate of the phosphorus source solution in the second pipeline is 0.2 L / min to 2 L / min, and / or The manufacturing method according to claim 2, wherein the flow rates of the metal salt solution and the phosphorus source solution are the same. **Claim 9** The residence time in the first reaction kettle during the growth process of the manganese iron phosphate precursor is 1 h to 4 h, and / or The residence time in the second reaction kettle during the growth process of the manganese iron phosphate precursor is 1 h to 16 h, and / or The manufacturing method according to claim 2, wherein the residence time in the aging kettle during the growth process of the manganese iron phosphate precursor is 1 h to 48 h. **Claim 10** The volume of the first reaction kettle is less than or equal to the volume of the second reaction kettle, and / or The volume of the first reaction kettle is less than or equal to the volume of the aging kettle, and / or The manufacturing method according to claim 2, wherein the volume of the second reaction kettle is less than or equal to the volume of the aging kettle. **Claim 11** The metal salts required for manufacturing the manganese iron phosphate precursor include water-soluble iron salts, water-soluble manganese salts, and salts of water-soluble doping element M, where M represents a doping element for manganese sites and iron sites, and includes one or more of Co, Mg, Zn, Ca, Ti, V, Ni, and Cr. The manufacturing method according to claim 2. **Claim 12** The phosphorus source required for manufacturing the manganese iron phosphate precursor includes one or more of phosphoric acid and water-soluble phosphates. The manufacturing method according to claim 2. **Claim 13** The manufacturing method according to claim 2, wherein the oxidizing agent contains one or more of hydrogen peroxide solution, nitric acid, sodium hypochlorite, potassium hypochlorite, sodium chlorate, and potassium chlorate. **Claim 14** The concentration of the metal salt solution is 0.5 mol / L to 2 mol / L, and / or, The concentration of the phosphorus source solution is 0.5 mol / L to 2 mol / L, and / or, The molar ratio of the metal salt to the phosphorus source is 1:1 to 1:3, the manufacturing method according to claim 2.

15. The stirring speed of the first material dissolving kettle is 100 r / min to 500 r / min, and / or, The stirring speed of the second material dissolving kettle is 100 r / min to 500 r / min, and / or, The stirring speed of the first reaction kettle is 100 r / min to 500 r / min, and / or, The stirring speed of the second reaction kettle is 100 r / min to 500 r / min, and / or, The stirring speed of the aging kettle is 100 r / min to 500 r / min, the manufacturing method according to claim 2.

16. In step S3, the drying temperature is 200 °C to 300 °C, and / or, In step S3, the drying time is 3 h to 8 h, and / or, In step S3, the drying atmosphere is a protective gas atmosphere, and the protective gas includes nitrogen gas, inert gas or a combination thereof, the manufacturing method according to claim 2.

17. The manganese iron phosphate precursor has the chemical formula Fe ｘ Mn ｙ M １－ｘ－ｙ P １－ｍ Q ｍ O ４ where 0 < x < 1, 0 < y < 1, 0 ≤ 1 - x - y < 1, 0 ≤ m ≤ 0.1, M represents a doping element for the manganese site and the iron site, includes one or more of Co, Mg, Zn, Ca, Ti, V, Ni, Cr, Q represents a doping element for the phosphorus site, includes one or more of B, S, Si, and N, and the manganese iron phosphate precursor is electrically neutral. The manufacturing method according to claim 2.

18. The manganese iron phosphate precursor has a spherical shape, and / or, The manganese iron phosphate precursor is orthorhombic, and the space group is pmnb, the manufacturing method according to claim 17.

19. The manganese iron phosphate precursor satisfies 1 < Dv90 / Dv50 ≤ 2 for the volume-based particle size distribution Dv90 and Dv50, and / or, The manganese iron phosphate precursor has a volume-based particle size distribution Dv50 of 1 μm to 10 μm, the manufacturing method according to claim 17 or 18.

20. At least, The manganese iron phosphate precursor manufactured by the manufacturing method according to claim 2, a lithium source, a doping element N source, and a doping element R source are uniformly mixed at a preset ratio to obtain a mixed raw material, where N represents a doping element at the lithium site and includes one or more of Zn, Al, Na, K, Mg, Nb, Mo, and W, and R represents a doping element at the oxygen site and includes one or more of S, F, Cl, and Br in step S10, By subjecting the mixed raw material obtained in step S10 to a sintering process, lithium iron manganese phosphate is obtained, and the lithium iron manganese phosphate has the chemical formula Li ａ N ｂ Fe ｘ Mn ｙ M １－ｘ－ｙ P １－ｍ Q ｍ O ４－ｎ R ｎ where M represents a doping element for the manganese site and the iron site, includes one or more of Co, Mg, Zn, Ca, Ti, V, Ni, Cr; N represents a doping element for the lithium site, includes one or more of Zn, Al, Na, K, Mg, Nb, Mo, and W; Q represents a doping element for the phosphorus site, includes one or more of B, S, Si, and N; R represents a doping element for the oxygen site, includes one or more of S, F, Cl, and Br; 0.9 ≤ a ≤ 1.1, 0 ≤ b ≤ 0.1, 0 < x < 1, 0 < y < 1, 0 ≤ 1 - x - y < 1, 0 ≤ m ≤ 0.1, 0 ≤ n ≤ 0.1, and the lithium iron manganese phosphate is electrically neutral; step S20, and includes a method for manufacturing lithium iron manganese phosphate.

21. In step S10, a carbon source is further added to the mixed raw material, the manufacturing method according to claim 20.

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