Continuous reaction system, iron manganese oxalate precursor, lithium iron manganese phosphate, production method, and secondary battery

Abstract

The present application provides a continuous reaction system, a manganese iron oxalate precursor, a lithium manganese iron phosphate, and a manufacturing method and a secondary battery. The manufacturing method of the manganese iron oxalate precursor provided by the present application is a continuous manufacturing method, which improves production efficiency, simplifies the manufacturing process, and can obtain a manganese iron oxalate precursor with small particle size, narrow particle size distribution, uniform element distribution, high crystallinity, regular shape, 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, iron manganese oxalate precursor, lithium iron manganese phosphate, a 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 for 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 iron manganese 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. Iron manganese oxalate is one of the important raw materials for manufacturing lithium iron manganese phosphate, and the impact of its performance on the performance of lithium iron manganese phosphate and secondary batteries is extremely important. However, currently, iron manganese oxalate can be obtained by using an intermittent manufacturing method, so there are problems such as low manufacturing efficiency, complex 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 objective of this application is to provide a continuous reaction system, an iron manganese oxalate precursor, lithium iron manganese phosphate, a manufacturing method, and a secondary battery, aiming to improve the manufacturing efficiency of the iron manganese oxalate precursor, simplify the manufacturing process of the iron manganese oxalate precursor, and obtain an iron manganese oxalate precursor with small particle size, narrow particle size distribution, uniform element distribution, high crystallinity, regular shape, 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 oxalate 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, a material storage kettle, and an ultrasonic reaction device. The first material dissolution kettle is used to contain a metal salt solution necessary for manufacturing the iron manganese oxalate precursor. The second material dissolution kettle is used to contain a precipitant solution necessary for manufacturing the iron manganese oxalate 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 discharge port of the first material dissolution kettle and the second discharge port of the second material dissolution kettle respectively through two pipelines. Thereby, the first reaction kettle contains and mixes the metal salt solution and the precipitant solution and then reacts them to generate a first reaction 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 through a 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 material storage kettle includes a third supply port, a fourth supply port, a third discharge port, and a third overflow port. The third supply port of the material storage kettle communicates with the second overflow port of the second reaction kettle through a pipeline. Thereby, the material storage kettle contains the second reaction solution from the second reaction kettle and continuously reacts it to generate a third reaction solution. The third discharge port and the fourth supply port of the material storage kettle are in circulating communication with the ultrasonic reaction device through a circulation pipeline and a circulation pump. Thereby, the third reaction solution in the material storage kettle is refined by the action of ultrasonic cavitation. When the liquid level of the third reaction solution is higher than the third overflow port of the material storage kettle, the third reaction solution flows out through the third overflow port of the material storage kettle.

[0005] In any embodiment of the present application, the continuous reaction system further includes a first metering pump and a second metering pump. Both ends of the first metering pump communicate with the first discharge port of the first material dissolution kettle and the first supply port of the first reaction kettle respectively through pipelines, thereby adjusting the flow rate of the metal salt solution. Both ends of the second metering pump communicate with the second discharge port of the second material dissolution kettle and the first supply port of the first reaction kettle respectively through pipelines, thereby adjusting the flow rate of the precipitant solution.

[0006] In any embodiment of the present application, the continuous reaction system further includes a cooling water circulation pipeline installed outside the ultrasonic reactor.

[0007] According to the second aspect of the present application, there is provided a manufacturing method for manufacturing an iron manganese oxalate precursor through the continuous reaction system of the first aspect of the present application. At least, a metal salt solution necessary for manufacturing the iron manganese oxalate precursor is added to a first reaction kettle, and a precipitant solution necessary for manufacturing the iron manganese oxalate precursor is added to a second material dissolution kettle in step S1. The metal salt solution in the first material dissolution kettle and the precipitant solution in the second material dissolution kettle are respectively transported to the first reaction kettle through different pipelines, mixed and then reacted to generate a first reaction solution. When the liquid level of the first reaction solution is higher than the overflow port of the first reaction kettle, the first reaction solution is automatically transported to the second reaction kettle, and then the reaction is continued to generate a second reaction solution. When the liquid level of the second reaction solution is higher than the overflow port of the second reaction kettle, the second reaction solution is automatically transported to the material storage kettle, and the reaction is continued to generate a third reaction solution. At the same time, the third reaction solution is pumped to the ultrasonic reactor through a circulation pipeline and a circulation pump, and the crystal grains in the third reaction solution are refined by the action of ultrasonic cavitation in the ultrasonic reactor and then pumped back to the material storage kettle. When the liquid level of the third reaction solution is higher than the overflow port of the material storage kettle, the third reaction solution automatically flows out through the overflow port of the material storage 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 material storage kettle are all under a protective gas atmosphere and each kettle maintains a stirring state in step S2. The third reaction solution obtained from the overflow port of the material storage kettle is centrifuged, washed and dried to obtain the iron manganese oxalate precursor in step S3.

[0008] The method for manufacturing the iron manganese oxalate precursor provided by this application is a continuous manufacturing method, which has the advantages of high manufacturing efficiency, high energy efficiency, simple process, easy operation, and low labor cost, and is particularly suitable for large-scale industrial production. The iron manganese oxalate precursor obtained by the manufacturing method provided by this application has the advantages of small particle size, narrow particle size distribution, uniform element distribution, high crystallinity, regular shape, and high stability and consistency in batch production. When it is used as a raw material to manufacture lithium iron manganese phosphate by the solid-phase sintering method, uniform mixing of lithium elements and multiple metal elements can be realized. As a result, lithium ions have a faster diffusion rate and are more likely to be occluded in the lithium iron manganese phosphate precursor, and excellent electrical and chemical properties can be imparted to the manufactured lithium iron manganese phosphate. The method for manufacturing the iron manganese oxalate precursor provided by this application further has good flexibility in production, and at the same time, the crystal growth rate can be controlled to adjust the size and shape of crystal grains, so as to meet different production requirements and manufacture lithium iron manganese phosphate with different particle sizes.

[0009] In any embodiment of this application, a complexing agent is further added to the first material dissolution tank. Preferably, the complexing agent includes one or more of aminocarboxylates, hydroxycarboxylates, and organic phosphonates. More preferably, it includes one or more of sodium ethylene diamine tetramethylene phosphate, sodium ethylenediaminetetraacetate, sodium gluconate, and sodium citrate. Thereby, iron manganese oxalate precursor particles with high purity (for example, purity ≥ 99.7%) and uniformly distributed metal elements can be obtained, and the difference between the molar ratio of each metal element in the obtained iron manganese oxalate precursor particles and the molar ratio of each metal element in the raw material is small, and accurate control of the metal element content can be realized.

[0010] 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 material storage kettle is lower than that of the second reaction kettle. Thereby, not only can the particle size of the obtained iron manganese oxalate precursor be adjusted, but also it is helpful to obtain iron manganese oxalate precursor particles with a narrow particle size distribution, uniform element distribution, high crystallinity, and regular shape.

[0011] In any embodiment of the present application, the reaction temperature of the first reaction kettle is 20°C to 30°C.

[0012] In any embodiment of the present application, the reaction temperature of the second reaction kettle is 40°C to 90°C, preferably 40°C to 60°C.

[0013] In any embodiment of the present application, the reaction temperature of the material storage kettle is 20°C to 30°C.

[0014] In any embodiment of the present application, the flow rate of the metal salt solution is 0.5 L / min to 6 L / min, preferably 2 L / min to 6 L / min.

[0015] In any embodiment of the present application, the flow rate of the precipitant solution is 0.5 L / min to 6 L / min, preferably 2 L / min to 6 L / min.

[0016] In any embodiment of the present application, the flow rates of the metal salt solution and the precipitant solution are the same, which helps to improve the consistency of the obtained iron manganese oxalate precursor particles.

[0017] In any embodiment of the present application, the residence time of the iron manganese oxalate precursor in the first reaction kettle during the growth process is 10 min to 2 h, preferably 10 min to 30 min.

[0018] In any embodiment of the present application, the residence time of the iron manganese oxalate precursor in the second reaction kettle during the growth process is 10 min to 10 h, preferably 30 min to 6 h, more preferably 30 min to 90 min.

[0019] In any embodiment of the present application, the residence time in the material storage kettle during the growth process of the iron manganese oxalate precursor is 10 min to 10 h, preferably 30 min to 6 h, and more preferably 30 min to 90 min.

[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 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 - 5), and more preferably 1:3. This helps the obtained iron manganese oxalate precursor particles to have a higher crystallinity.

[0021] In any embodiment of the present application, the volume of the first reaction kettle is less than or equal to the volume of the material storage kettle. Preferably, the ratio of the volume of the first reaction kettle to the volume of the material storage kettle is 1:(1 - 5), and more preferably 1:3. Thereby, the obtained iron manganese oxalate precursor particles can have a smaller particle size.

[0022] In any embodiment of the present application, the volume of the second reaction kettle is the same as the volume of the material storage kettle.

[0023] In any embodiment of the present application, the frequency of the ultrasonic reaction device is 15 KHz to 60 KHz, preferably 30 KHz to 60 KHz. This is advantageous for manufacturing iron manganese oxalate precursors on the nano - order.

[0024] In any embodiment of the present application, the metal salts required to produce the iron manganese oxalate precursor include a water - soluble divalent iron salt, a water - soluble divalent manganese salt, and preferably a divalent 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, Cr.

[0025] In any embodiment of the present application, preferably, the water-soluble ferrous salt contains one or more of ferrous chloride, ferrous bromide, ferrous nitrate, ferrous sulfate, ferrous acetate, ferrous fluorosilicate, and ferrous perchlorate.

[0026] In any embodiment of the present application, preferably, the water-soluble manganese(II) salt contains one or more of manganese(II) chloride, manganese(II) bromide, manganese(II) nitrate, manganese(II) sulfate, manganese(II) acetate, and manganese(II) perchlorate.

[0027] In any embodiment of the present application, preferably, the divalent salt of the water-soluble doping element M contains one or more of the hydrochloride, nitrate, sulfate, and acetate of the doping element M.

[0028] In any embodiment of the present application, the precipitant contains one or more of oxalic acid and water-soluble oxalates. Preferably, the water-soluble oxalate contains one or more of lithium oxalate, sodium oxalate, potassium oxalate, and ammonium oxalate.

[0029] In any embodiment of the present application, the concentration of the metal salt solution is 0.5 mol / L to 2 mol / L, preferably 0.5 mol / L to 1 mol / L.

[0030] In any embodiment of the present application, the concentration of the precipitant solution is 0.5 mol / L to 2 mol / L, preferably 0.5 mol / L to 1 mol / L.

[0031] In any embodiment of the present application, the molar ratio of the metal salt to the precipitant is 1:1 to 1:5.

[0032] In any embodiment of the present application, the stirring speed of the first material dissolution kettle is 300 r / min to 600 r / min.

[0033] In any embodiment of the present application, the stirring speed of the second material dissolution kettle is 300 r / min to 600 r / min.

[0034] In any embodiment of the present application, the stirring speed of the first reaction kettle is 300 r / min to 600 r / min.

[0035] In any embodiment of the present application, the stirring speed of the second reaction kettle is 300 r / min to 600 r / min.

[0036] In any embodiment of the present application, the stirring speed of the material storage kettle is 300 r / min to 600 r / min.

[0037] In any embodiment of the present application, the protective gas includes nitrogen gas, inert gas or a combination thereof.

[0038] According to the third aspect of the present application, there is provided an iron manganese oxalate precursor produced by the production method of the second aspect of the present application, with the chemical formula Fe x Mn y M 1-x-y C2O4·2H2O, 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. M represents a doping element for manganese sites and iron sites, preferably including one or more of Co, Mg, Zn, Ca, Ti, V, Ni, Cr, and the iron manganese oxalate precursor is electrically neutral.

[0039] The iron manganese oxalate precursor provided by the present application has the advantages of small particle size, narrow particle size distribution, uniform element distribution, high crystallinity, and regular shape.

[0040] In any embodiment of the present application, the volume-based particle size distributions Dv90 and Dv50 of the iron manganese oxalate precursor satisfy 1 < Dv90 / Dv50 ≤ 2, preferably 1.3 ≤ Dv90 / Dv50 ≤ 1.7.

[0041] In any embodiment of the present application, the volume-based particle size distribution Dv50 of the iron manganese oxalate precursor is 200 nm to 600 nm, preferably 230 nm to 510 nm.

[0042] In any embodiment of the present application, the volume-based particle size distribution Dv90 of the iron manganese oxalate precursor is 260 nm to 800 nm, preferably 320 nm to 730 nm.

[0043] According to the fourth aspect of the present application, there is provided a manufacturing method for manufacturing lithium iron manganese phosphate, including at least: the iron manganese oxalate precursor manufactured by the manufacturing method of the second aspect of the present application or the iron manganese oxalate precursor of the third aspect of the present application, a lithium source, a phosphorus source, an optional doping element N source, an optional doping element Q source, and an optional doping element R source are uniformly mixed at a preset ratio to obtain a mixed raw material, where 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 in step S10; and the mixed raw material obtained in step S10 is sintered to obtain lithium iron manganese phosphate, 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 nIt has, M represents a doping element of a manganese site and an iron site, preferably includes one or more of Co, Mg, Zn, Ca, Ti, V, Ni, Cr, N represents a doping element of a lithium site, preferably includes one or more of Zn, Al, Na, K, Mg, Nb, Mo and W, Q represents a doping element of a phosphorus site, preferably includes one or more of B, S, Si and N, R represents a doping element of an oxygen site, preferably includes 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 in step S20, including.

[0044] The lithium iron manganese phosphate obtained by the manufacturing method of the present application can realize a uniform mixing of a lithium element and a plurality of metal elements. As a result, lithium ions have a faster diffusion rate and are more likely to be occluded in the lithium iron manganese phosphate precursor, and excellent electrical and chemical properties can be imparted to the manufactured lithium iron manganese phosphate.

[0045] In any embodiment of the present application, in step S10, a carbon source is further added to the mixed raw materials, whereby lithium iron manganese phosphate coated with carbon can be manufactured.

[0046] According to the fifth aspect of the present application, there is provided lithium iron manganese phosphate which is manufactured by the manufacturing method of the fourth aspect of the present application and can have excellent electrical and chemical properties.

[0047] According to the sixth aspect of the present application, there is provided a secondary battery including lithium iron manganese phosphate manufactured by the manufacturing method of the fourth aspect of the present application.

Brief Description of the Drawings

[0048] To more clearly explain the technical solutions in the embodiments of the present application, the drawings necessary for the embodiments of the present application will be 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 these drawings without creative efforts. In the drawings, the drawings are not drawn according to the actual ratio.

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0049] Hereinafter, the continuous reaction system, iron manganese oxalate precursor, lithium iron manganese phosphate, manufacturing method, and embodiments of the secondary battery of the present application will be described in detail with appropriate reference to the drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters or duplicate descriptions of substantially the same structures may be omitted. This is to prevent the following description from becoming unnecessarily redundant and to facilitate the understanding of 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.

[0050] 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 anticipated. 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 expression 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 expression 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 integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0051] 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.

[0052] 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.

[0053] All steps of the present application can be carried out 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 carried out in sequence, or steps S2 and S1 carried out 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.

[0054] 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.

[0055] 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).

[0056] 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 primary-secondary relationship.

[0057] In the present application, the terms "a plurality of" and "plural" mean two or more.

[0058] The first aspect of the embodiment of the present application provides a continuous reaction system for producing an iron manganese oxalate precursor.

[0059] As shown in FIG. 1, the continuous reaction system includes a first material dissolving tank 1, a second material dissolving tank 2, a first reaction tank 3, a second reaction tank 4, a material storage tank 5, and an ultrasonic reaction device 6. The first material dissolving tank 1 is used to contain the metal salt solution required for manufacturing the iron manganese oxalate precursor. The second material dissolving tank 2 is used to contain the precipitant solution required for manufacturing the iron manganese oxalate precursor. The first reaction tank 3 has a first supply port 7 and a first overflow port 8. The first supply port 7 of the first reaction tank communicates with the first discharge port 9 of the first material dissolving tank and the second discharge port 10 of the second material dissolving tank respectively through two pipelines. Thereby, the first reaction tank 3 contains and mixes the metal salt solution and the precipitant solution and then reacts them to generate a first reaction solution. The second reaction tank 4 has a second supply port 11 and a second overflow port 12. The second supply port 11 of the second reaction tank communicates with the first overflow port 8 of the first reaction tank through a pipeline. Thereby, the second reaction tank 4 contains the first reaction solution from the first reaction tank 3 and continuously reacts it to generate a second reaction solution. The material storage tank 5 includes a third supply port 13, a fourth supply port 14, a third discharge port 15, and a third overflow port 16. The third supply port 13 of the material storage tank communicates with the second overflow port 12 of the second reaction tank through a pipeline. Thereby, the material storage tank 5 contains the second reaction solution from the second reaction tank 4 and continuously reacts it to generate a third reaction solution. The third discharge port 15 and the fourth supply port 14 of the material storage tank are in circulation communication with the ultrasonic reaction device 6 through a circulation pipeline and a circulation pump 17. Thereby, the third reaction solution in the material storage tank 5 is refined by the action of ultrasonic cavitation. When the liquid level of the third reaction solution is higher than the third overflow port 16 of the material storage tank, the third reaction solution flows out through the third overflow port 16 of the material storage tank.

[0060] In some embodiments, the continuous reaction system further includes a first metering pump 18 and a second metering pump 19. Both ends of the first metering pump 18 communicate with the first discharge port 9 of the first material dissolution kettle and the first supply port 7 of the first reaction kettle through pipelines respectively, thereby adjusting the flow rate of the metal salt solution. Both ends of the second metering pump 19 communicate with the second discharge port 10 of the second material dissolution kettle and the first supply port 7 of the first reaction kettle through pipelines respectively, thereby adjusting the flow rate of the precipitant solution.

[0061] In some embodiments, the ultrasonic reaction device 6 includes an ultrasonic reaction tank, an ultrasonic generator, and an ultrasonic converter. In the present application, the operating principle of the ultrasonic reaction device is to use the ultrasonic generator to generate a high-frequency vibration signal, and then convert the signal into high-frequency mechanical vibration through the ultrasonic converter, and continuously propagate it into the third reaction liquid in the ultrasonic reaction kettle, thereby refining the crystal grains (i.e., manganese iron oxalate precursor particles) in the third reaction liquid.

[0062] In some embodiments, the continuous reaction system further includes a cooling water circulation pipeline 20 installed outside the ultrasonic reaction device 6. When using the ultrasonic reaction device, part of the energy may promote the temperature rise of the main body of the ultrasonic reaction device. By installing the cooling water circulation pipeline, the temperature of the main body of the ultrasonic reaction device can be lowered to protect the device.

[0063] In some embodiments, a first shut-off valve 21 is further installed in the pipeline between the first discharge port 9 of the first material dissolution kettle and the first metering pump 18.

[0064] In some embodiments, a second shut-off valve 22 is further installed in the pipeline between the first discharge port 9 of the first material dissolution kettle and the second metering pump 19.

[0065] In some embodiments, a third shut-off valve 23 is further installed in the pipeline between the first overflow port 8 of the first reaction kettle and the second supply port 11 of the second reaction kettle.

[0066] In some embodiments, a fourth shut-off valve 24 is further installed in the pipeline between the second overflow port 12 of the second reaction kettle and the third supply port 13 of the material storage kettle.

[0067] In some embodiments, a fifth shut-off valve 25 is further installed in the circulation pipeline between the third discharge port 15 of the material storage kettle and the circulation pump 17.

[0068] When manufacturing the iron manganese oxalate precursor, the first shut-off valve 21, the second shut-off valve 22, the third shut-off valve 23, the fourth shut-off valve 24, and the fifth shut-off valve 25 all remain in the open state, thereby ensuring continuous material supply and continuous discharge, and enabling multiple kettles to react simultaneously.

[0069] In some embodiments, stirring devices are installed in the first material dissolution kettle 1, the second material dissolution kettle 2, the first reaction kettle 3, the second reaction kettle 4, and the material storage kettle 5.

[0070] In some embodiments, in order to adjust the temperature of each kettle as needed, heating devices may be further installed in the first material dissolution kettle 1, the second material dissolution kettle 2, the first reaction kettle 3, the second reaction kettle 4, and the material storage kettle 5.

[0071] In some embodiments, the first overflow port 8 is installed at the top of the first reaction kettle 3, the second overflow port 12 is installed at the top of the second reaction kettle 4, and the third overflow port 16 is installed at the top of the material storage kettle 5.

[0072] The second aspect of the embodiment of the present application provides a manufacturing method for manufacturing an iron manganese oxalate precursor through the continuous reaction system of the first aspect of the embodiment of the present application. At least, a metal salt solution necessary for manufacturing the iron manganese oxalate precursor is added to a first reaction kettle, and a precipitant solution necessary for manufacturing the iron manganese oxalate precursor is added to a second material dissolution kettle in step S1. The metal salt solution in the first material dissolution kettle and the precipitant solution in the second material dissolution kettle are respectively transported to the first reaction kettle through different pipelines, mixed and then reacted to generate a first reaction solution. When the liquid level of the first reaction solution is higher than the overflow port of the first reaction kettle, the first reaction solution is automatically transported to the second reaction kettle, and then the reaction is continued to generate a second reaction solution. When the liquid level of the second reaction solution is higher than the overflow port of the second reaction kettle, the second reaction solution is automatically transported to a material storage kettle, the reaction is continued to generate a third reaction solution. At the same time, the third reaction solution is pumped to an ultrasonic reaction device through a circulation pipeline and a circulation pump, and the crystal grains in the third reaction solution are refined by the action of ultrasonic cavitation of the ultrasonic reaction device and then pumped back to the material storage kettle. When the liquid level of the third reaction solution is higher than the overflow port of the material storage kettle, the third reaction solution automatically flows out through the overflow port of the material storage 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 material storage kettle are all under a protective gas atmosphere and each kettle maintains a stirring state in step S2. The third reaction solution obtained from the overflow port of the material storage kettle is centrifuged, washed and dried to obtain an iron manganese oxalate precursor in step S3.

[0073] Many of the conventional reaction systems for manufacturing an iron manganese lithium oxalate precursor adopt an intermittent manufacturing process in which a single reaction kettle or a plurality of reaction kettles are connected in parallel. Therefore, there is a disadvantage of low manufacturing efficiency. Moreover, when producing by a 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 manufacturing process becomes complicated and the labor cost is high.

[0074] This application adopts a continuous reaction system to produce an iron manganese oxalate precursor. In the continuous reaction system of this application, the first reaction kettle, the second reaction kettle, and the material storage kettle adopt a series connection method, thereby ensuring continuous material supply and continuous discharge, and enabling multiple kettles to react simultaneously. Therefore, the method for producing an iron manganese oxalate 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.

[0075] The method for producing an iron manganese oxalate precursor is generally the coprecipitation method. In the precipitation process, the crystal nucleus growth rate is fast, and it is difficult to control the size and shape of the obtained crystals. Therefore, the iron manganese oxalate precursor obtained by the conventional batch production method has the disadvantages of large particle size (for example, the volume-based particle size distribution Dv50 is usually 10μm - 40μm), wide particle size distribution, and non-uniform element distribution. Therefore, when producing lithium iron manganese phosphate using the iron manganese oxalate precursor obtained by the conventional batch production method as a raw material, it is necessary to perform ball milling for a long time to reduce the particle size. This process consumes time and energy, and it is also difficult to achieve the uniformity of the mixed materials during the process of producing lithium iron manganese phosphate. In addition, the iron manganese lithium oxalate precursor obtained by the conventional batch production method also has the disadvantages of large fluctuations in product quality and poor stability and consistency in batch production.

[0076] The method for manufacturing the iron manganese oxalate precursor provided by this application is a continuous manufacturing method. In the continuous manufacturing process, the residence times in the first reaction kettle, the second reaction kettle, and the material storage kettle during the growth process of each iron manganese oxalate precursor particle are the same, and all pass through the ultrasonic cavitation effect at the same frequency. Therefore, due to the strong shearing force caused by the ultrasonic cavitation effect, the particle size of the iron manganese oxalate precursor can be refined. Therefore, compared with the lithium iron manganese oxalate precursor obtained by the conventional batch manufacturing method, the iron manganese oxalate precursor obtained by the manufacturing method provided by this application has the advantages of small particle size, narrow particle size distribution, uniform element distribution, high crystallinity, regular shape, and high stability and consistency in batch production. When using it as a raw material to manufacture lithium iron manganese phosphate by the solid-phase sintering method, a uniform mixing of lithium elements and multiple metal elements can be realized. As a result, lithium ions have a faster diffusion rate and are more likely to be occluded in the lithium iron manganese phosphate precursor, and excellent electrical and chemical properties can be imparted to the manufactured lithium iron manganese phosphate.

[0077] In the method for manufacturing the iron manganese oxalate precursor provided by this application, parameters such as the flow rates of the metal salt solution and the precipitant solution, the residence time in each kettle during the growth process of the iron manganese oxalate precursor, the reaction temperature of each kettle, and the frequency of the ultrasonic reaction device can all be accurately adjusted. Therefore, the method for manufacturing the iron manganese oxalate precursor provided by this application also has good flexibility in production.

[0078] In the growth process of the iron manganese oxalate precursor, the residence time in each kettle (the first reaction kettle, the second reaction kettle, and the material storage kettle) shows a negative correlation with the flow rates of the metal salt solution and the precipitant solution, and a positive correlation with the volume of each kettle. When the flow rates of the metal salt solution and the precipitant solution are fast, the residence time of the iron manganese oxalate precursor in each kettle is short; when the flow rates of the metal salt solution and the precipitant solution are slow, the residence time of the iron manganese oxalate precursor in each kettle is long. When the volume of each kettle is small, the residence time of the iron manganese oxalate precursor in each kettle is short; when the volume of each kettle is large, the residence time of the iron manganese oxalate precursor in each kettle is long. Therefore, by adjusting the flow rates of the metal salt solution and the precipitant solution and the volume of each kettle, the adjustment of the particle size and shape of the iron manganese oxalate precursor can be realized.

[0079] Since the reaction temperature also affects the particle size of the obtained iron manganese oxalate precursor, by adjusting the reaction temperature of each kettle within different ranges, the adjustment of the particle size and shape of the iron manganese oxalate precursor can be realized.

[0080] Since the frequency of the ultrasonic reaction device also affects the particle size of the obtained iron manganese oxalate precursor, by adjusting the frequency of the ultrasonic reaction device, different degrees of particle refinement effects can be realized, and the adjustment of the particle size of the iron manganese oxalate precursor can be realized.

[0081] Therefore, the method for manufacturing the iron manganese oxalate precursor provided by the present application can control the crystal growth rate and adjust the size and shape of the crystal grains, thereby meeting different production requirements and manufacturing lithium iron manganese phosphate with different particle sizes.

[0082] In some embodiments, a complexing agent is further added to the first material dissolution kettle.

[0083] When producing an iron manganese oxalate precursor by coprecipitation, since there are differences 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 oxalate precursor particles and the molar ratio of each metal element in the raw materials, which affects the performance and consistency of the product. In the method for producing an iron manganese oxalate precursor provided by the present application, a complexing agent is further added to the first material dissolving kettle. The complexing agent can achieve the purpose of complexing metal ions and controlling free metal ions, thereby improving the precipitation conversion efficiency of metal ions, reducing the difference in the precipitation rates of different metal ions in the reaction solution, and realizing uniform coprecipitation. Therefore, when a complexing agent is added to the first material dissolving kettle, the method for producing an iron manganese oxalate precursor provided by the present application can obtain iron manganese oxalate precursor particles with high purity (for example, purity ≥ 99.7%) and uniform distribution of metal elements, and the difference between the molar ratio of each metal element in the obtained iron manganese oxalate precursor particles and the molar ratio of each metal element in the raw materials is small, and accurate control of the metal element content can be realized.

[0084] Preferably, the complexing agent includes one or more of aminocarboxylates, hydroxycarboxylates, and organic phosphonates. More preferably, the complexing agent includes one or more of sodium ethylene diamine tetramethylene phosphate, sodium ethylenediaminetetraacetate, sodium gluconate, and sodium citrate.

[0085] Preferably, the mass concentration of the complexing agent is 10 wt% or less, more preferably 1 wt% - 10 wt%, based on the total mass of the metal salt solution.

[0086] 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 material storage kettle is lower than that of the second reaction kettle.

[0087] In the method for producing the iron manganese oxalate precursor provided by the present application, the first reaction kettle, the second reaction kettle, and the material storage kettle adopt a series communication method, and the reaction temperatures of the first reaction kettle and the material storage kettle are set lower than the reaction temperature 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 precipitant solution and rapid preliminary nucleation can be realized, and the low reaction temperature can also suppress the condensation growth of crystal nuclei in the first reaction solution. Thereby, metal ions and oxalate ions ((C2O4) 2- ) can be co-precipitated to form a large number of crystal nuclei with uniform size and uniform element distribution, which is beneficial for the crystal nuclei to grow and crystallize better in the 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 crystallinity of the formed crystals can be improved. Since the reaction temperature of the material storage kettle is low, in the material storage kettle, further crystallization and growth of crystals can be realized, the crystallinity, uniformity and consistency of the crystals can be improved. At the same time, the material storage kettle has a low reaction temperature, which prevents the temperature of the reaction solution from becoming too high, and avoids the ultrasonic reaction device from overheating and affecting the service life of the ultrasonic conversion device. In addition, the reaction temperature of the material storage kettle is lower than the reaction temperature of the second reaction kettle, so that when the reaction solution flows from the second reaction kettle to the material storage kettle, it plays a role in cooling the reaction solution.

[0088] Therefore, by adjusting the reaction temperature of each kettle, not only can the particle size of the obtained iron manganese oxalate precursor be adjusted, but also it is helpful to obtain iron manganese oxalate precursor particles with a narrow particle size distribution, uniform element distribution, high crystallinity, and regular shape.

[0089] In some embodiments, preferably, the reaction temperature of the first reaction kettle is 20°C to 30°C.

[0090] In some embodiments, preferably, the reaction temperature of the second reaction kettle is 40°C to 90°C, more preferably 40°C to 60°C.

[0091] In some embodiments, preferably, the reaction temperature of the material storage kettle is 20°C to 30°C.

[0092] In some embodiments, the flow rate of the metal salt solution (or the pump speed of the first metering pump) is 0.5 L / min to 6 L / min, preferably 2 L / min to 6 L / min.

[0093] In some embodiments, the flow rate of the precipitant solution (or the pump speed of the second metering pump) is 0.5 L / min to 6 L / min, preferably 2 L / min to 6 L / min.

[0094] In some embodiments, the flow rates of the metal salt solution and the precipitant 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 iron manganese oxalate precursor particles obtained.

[0095] In some embodiments, the residence time in the first reaction kettle during the growth process of the iron manganese oxalate precursor is 10 min to 2 h, preferably 10 min to 30 min.

[0096] In some embodiments, the residence time in the second reaction kettle during the growth process of the iron manganese oxalate precursor is 10 min to 10 h, preferably 30 min to 6 h, more preferably 30 min to 90 min.

[0097] In some embodiments, the residence time in the material storage kettle during the growth process of the iron manganese oxalate precursor is 10 min to 10 h, preferably 30 min to 6 h, more preferably 30 min to 90 min.

[0098] In some embodiments, the volume of the first reaction kettle is less than or equal to the volume of the second reaction kettle, so that the residence time of the iron manganese oxalate precursor particles generated therein in the second reaction kettle is long, which helps the obtained iron manganese oxalate 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:(1-5), more preferably 1:3.

[0099] In some embodiments, the volume of the first reaction kettle is less than or equal to the volume of the material storage kettle, so that the residence time of the iron manganese oxalate precursor particles generated therein in the material storage kettle is long, which helps the obtained iron manganese oxalate precursor particles to have a smaller particle size. Preferably, the ratio of the volume of the first reaction kettle to the volume of the material storage kettle is 1:(1-5), more preferably 1:3.

[0100] In some embodiments, preferably, the volume of the second reaction kettle is the same as the volume of the material storage kettle.

[0101] In some embodiments, preferably, the frequency of the ultrasonic reaction device is 15 KHz to 60 KHz, preferably 30 KHz to 60 KHz. This is advantageous for producing iron manganese oxalate precursors in the nano order.

[0102] In some embodiments, the metal salts required to produce the iron manganese oxalate precursor include a water-soluble divalent iron salt, a water-soluble divalent manganese salt, and preferably a divalent salt of a water-soluble doping element M, 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, Cr.

[0103] The water-soluble divalent iron salt may be various conventional compounds containing divalent iron ions that are soluble in water. Preferably, the water-soluble divalent iron salt includes one or more of ferrous chloride, ferrous bromide, ferrous nitrate, ferrous sulfate, ferrous acetate, ferrous fluorosilicate, and ferrous perchlorate.

[0104] The water-soluble divalent manganese salt may be various divalent manganese ion-containing compounds that are soluble in conventional water. Preferably, the water-soluble divalent manganese salt contains one or more of manganese(I) chloride, manganese(I) bromide, manganese(I) nitrate, manganese(I) sulfate, manganese(I) acetate, and manganese(I) perchlorate.

[0105] The divalent salt of the water-soluble doping element M may be various divalent M ion-containing compounds that are soluble in conventional water. Preferably, the divalent salt of the water-soluble doping element M contains one or more of the hydrochloride, nitrate, sulfate, and acetate of the doping element M.

[0106] In some embodiments, preferably, the precipitant contains one or more of oxalic acid and water-soluble oxalates. Preferably, the water-soluble oxalate contains one or more of lithium oxalate, sodium oxalate, potassium oxalate, and ammonium oxalate.

[0107] In some embodiments, the metal salt solution is an aqueous metal salt solution, which can be obtained, for example, by uniformly mixing a metal salt necessary for producing a manganese iron oxalate precursor and deionized water.

[0108] In some embodiments, the precipitant solution is an aqueous precipitant solution, which can be obtained, for example, by uniformly mixing a precipitant and deionized water.

[0109] In some embodiments, preferably, the concentration of the metal salt solution is 0.5 mol / L to 2 mol / L, and more preferably 0.5 mol / L to 1 mol / L.

[0110] In some embodiments, preferably, the concentration of the precipitant solution is 0.5 mol / L to 2 mol / L, and more preferably 0.5 mol / L to 1 mol / L.

[0111] In some embodiments, preferably, the molar ratio of the metal salt to the precipitant is 1:1 to 1:5.

[0112] During the reaction process, the first material dissolving kettle, the second material dissolving kettle, the first reaction kettle, the second reaction kettle and the material storage kettle all maintain a stirring state. In some embodiments, preferably, the stirring speed of the first material dissolving kettle is 300 r / min to 600 r / min. In some embodiments, preferably, the stirring speed of the second material dissolving kettle is 300 r / min to 600 r / min. In some embodiments, preferably, the stirring speed of the first reaction kettle is 300 r / min to 600 r / min. In some embodiments, preferably, the stirring speed of the second reaction kettle is 300 r / min to 600 r / min. In some embodiments, preferably, the stirring speed of the material storage kettle is 300 r / min to 600 r / min.

[0113] During the reaction process, protective gas is introduced into the first material dissolving kettle, the second material dissolving kettle, the first reaction kettle, the second reaction kettle and the material storage 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.

[0114] In the method for manufacturing the iron manganese oxalate precursor provided by the present application, unless otherwise specified, each raw material may be directly purchased.

[0115] According to the third aspect of the embodiment of the present application, an iron manganese oxalate precursor manufactured by the manufacturing method of the second aspect of the embodiment of the present application is provided, and the iron manganese oxalate precursor has the chemical formula Fe x Mn y M 1-x-y C2O4·2H2O, where 0 < x < 1, 0 < y < 1, 0 ≤ 1 - x - y < 1, M represents a doping element at the manganese site and the iron site, preferably includes one or more of Co, Mg, Zn, Ca, Ti, V, Ni, Cr, and the iron manganese oxalate precursor is electrically neutral.

[0116] Since the iron manganese oxalate precursor provided by the present application is produced by the production method of the second aspect of the embodiment of the present application, it has the advantages of small particle size, narrow particle size distribution, uniform element distribution, high crystallinity, and regular shape.

[0117] In some embodiments, the volume-based particle size distributions Dv90 and Dv50 of the iron manganese oxalate precursor satisfy 1 < Dv90 / Dv50 ≤ 2, and preferably, 1.3 ≤ Dv90 / Dv50 ≤ 1.7.

[0118] In some embodiments, the volume-based particle size distribution Dv50 of the iron manganese oxalate precursor is 200 nm to 600 nm, and preferably 230 nm to 510 nm.

[0119] In some embodiments, the volume-based particle size distribution Dv90 of the iron manganese oxalate precursor is 260 nm to 800 nm, and preferably 320 nm to 730 nm.

[0120] In some embodiments, preferably, 0.2 ≤ x ≤ 0.5.

[0121] In some embodiments, preferably, 0.5 ≤ y ≤ 0.8.

[0122] In some embodiments, 1 - x - y = 0, and in another embodiment, 0 < 1 - x - y ≤ 0.05.

[0123] According to a fourth aspect of the embodiment of the present application, a method for manufacturing lithium iron manganese phosphate is provided. At least, an iron manganese oxalate precursor produced by the manufacturing method of the second aspect of the embodiment of the present application or the iron manganese oxalate precursor of the third aspect of the embodiment of the present application, a lithium source, a phosphorus source, an optional doping element N source, an optional doping element Q 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 at the lithium site, preferably including one or more of Zn, Al, Na, K, Mg, Nb, Mo, and W. Q represents a doping element at the phosphorus site, preferably including one or more of B, S, Si, and N. R represents a doping element at the oxygen site, preferably including one or more of S, F, Cl, and Br. Step S10 includes obtaining a mixed raw material by uniformly mixing the above components. The obtained mixed raw material in step S10 is sintered to obtain lithium iron manganese phosphate. 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 at 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 at the lithium site, preferably including one or more of Zn, Al, Na, K, Mg, Nb, Mo, and W. Q represents a doping element at the phosphorus site, preferably including one or more of B, S, Si, and N. R represents a doping element at the oxygen site, preferably including one or more of S, F, Cl, and Br. Here, 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 includes the above steps.

[0124] The lithium iron manganese phosphate obtained by the above manufacturing method of the present application can achieve a uniform mixing of lithium element and a plurality of metal elements. As a result, lithium ions have a faster diffusion rate and are more likely to be occluded in the lithium iron manganese phosphate precursor, and excellent electrical and chemical properties can be imparted to the manufactured lithium iron manganese phosphate.

[0125] In some embodiments, the lithium source may be a lithium-containing compound known in the art used for manufacturing the positive electrode active material of lithium iron manganese phosphate. For example, the lithium source may include one or more of Li2CO3, LiOH, Li3PO4, and LiH2PO4.

[0126] In some embodiments, the phosphorus source may be a phosphorus-containing compound known in the art used for manufacturing the positive electrode active material of lithium iron manganese phosphate. For example, the phosphorus source may include one or more of (NH4)2HPO4, NH4H2PO4, (NH4)3PO4, and H3PO4.

[0127] 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.

[0128] In some embodiments, the doping element Q source includes one or more of the sulfate, borate, nitrate, and silicate salts of the doping element Q,

[0129] In some embodiments, the doping element R source includes one or more of the simple substance of the doping element R and the ammonium salt.

[0130] 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.

[0131] 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 produced.

[0132] 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.

[0133] In the above manufacturing method, the addition amount of each of the doping element N, Q, and R sources depends on the target doping amount, and the addition amounts of the lithium source and the phosphorus source conform to the stoichiometric ratio of lithium iron manganese 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, and the theoretical mass of the lithium source is the mass of the lithium source calculated based on the stoichiometric ratio of lithium iron manganese phosphate.

[0134] In the above manufacturing method, unless otherwise specified, each raw material may be directly purchased.

[0135] According to the fifth aspect of the embodiment of the present application, lithium iron manganese phosphate manufactured by the manufacturing method of the fourth aspect of the embodiment of the present application is provided.

[0136] 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 nIt has, M represents a doping element for the manganese site and the iron site, preferably includes one or more of Co, Mg, Zn, Ca, Ti, V, Ni, Cr, N represents a doping element for the lithium site, preferably includes one or more of Zn, Al, Na, K, Mg, Nb, Mo and W, Q represents a doping element for the phosphorus site, preferably includes one or more of B, S, Si and N, R represents a doping element for the oxygen site, preferably includes 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.

[0137] In some embodiments, carbon is coated on the surface of the lithium iron manganese phosphate, thereby improving the conductivity of the lithium iron manganese phosphate.

[0138] According to the sixth aspect of the embodiment of the present application, a secondary battery including lithium iron manganese phosphate manufactured by the manufacturing method of the fourth aspect of the embodiment of the present application is provided. The lithium iron manganese phosphate can be applied in a secondary battery as a positive electrode active material and helps to improve the electrical and chemical properties of the secondary battery. Example

[0139] The following examples describe the content disclosed in the present application in more detail. However, since various modifications and changes within the scope of the content disclosed in the present application will be apparent 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. Example 1

[0140] The iron(II) manganese oxalate precursor is produced by adopting the continuous reaction system shown in Fig. 1.

[0141] Ferrous chloride, a water-soluble divalent manganese salt; ferrous chloride, a water-soluble divalent iron salt; sodium ethylenediaminetetramethylenephosphate, a complexing agent; and deionized water are added to the 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 to divalent iron ions is 7:3, and the mass concentration of the complexing agent is 5 wt%. Ammonium oxalate, a precipitant, and deionized water are added to the second material dissolving kettle to prepare a precipitant solution with a concentration of 1 mol / L.

[0142] 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 material storage kettle, and the stirring speed of each kettle in the reaction process is 400 r / min. The reaction temperatures of the first reaction kettle and the material storage kettle are both controlled at room temperature (25 °C), the reaction temperature of the second reaction kettle is controlled at 40 °C, and the frequency of the ultrasonic reaction device is 60 KHz.

[0143] The metal salt solution and the precipitant solution are continuously conveyed from the first material dissolving kettle and the second material dissolving kettle to the first reaction kettle through two liquid supply pipes, mixed and reacted to generate a first reaction solution, and the flow rates of the metal salt solution and the precipitant solution are both 6 L / min.

[0144] After reacting for 10 minutes, 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.

[0145] After the reaction continues for 30 minutes, 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 material storage kettle to continue the reaction and generate the third reaction solution.

[0146] The third reaction solution in the material storage kettle is continuously pumped into the ultrasonic reactor through the circulation pipeline and the circulation pump, and after the iron manganese oxalate precursor particles in the third reaction solution are refined by the ultrasonic cavitation effect of the ultrasonic reactor, it is pumped back into the material storage kettle again.

[0147] After the reaction continues for 30 minutes, 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.

[0148] After the obtained third reaction solution is centrifuged and washed multiple times with a centrifuge, it is transferred to a dryer and dried at 120 °C for 6 hours to obtain an iron manganese oxalate precursor. Example 2

[0149] An iron manganese oxalate precursor is produced by adopting the continuous reaction system shown in Fig. 1.

[0150] Manganous nitrate as a water-soluble divalent manganese salt, ferrous nitrate as a water-soluble divalent iron salt, sodium ethylenediaminetetraacetate 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 1 mol / L. In the prepared metal salt solution, the molar ratio of divalent manganese ions to divalent iron ions is 7:3, and the mass concentration of the complexing agent is 3 wt%. Oxalic acid as a precipitant and deionized water are added to the second material dissolving kettle to prepare a precipitant solution with a concentration of 1 mol / L.

[0151] 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 material storage kettle, and the stirring speed of each kettle in the reaction process is 600 r / min. The reaction temperatures of the first reaction kettle and the material storage kettle are both controlled at room temperature (25 °C), the reaction temperature of the second reaction kettle is controlled at 60 °C, and the frequency of the ultrasonic reaction device is 30 KHz.

[0152] The metal salt solution and the precipitant solution are continuously conveyed from the first material dissolution kettle and the second material dissolution kettle to the first reaction kettle through two liquid supply pipes, mixed and reacted to generate the first reaction solution, and the flow rates of the metal salt solution and the precipitant solution are both 2 L / min.

[0153] After reacting for 30 min, 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 to the second reaction kettle to continue the reaction and generate the second reaction solution.

[0154] After the reaction continues for 90 min, 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 to the material storage kettle to continue the reaction and generate the third reaction solution.

[0155] The third reaction solution in the material storage kettle is continuously pumped to the ultrasonic reaction device through the circulation pipeline and the circulation pump, and after the iron manganese oxalate precursor particles in the third reaction solution are refined by the ultrasonic cavitation effect of the ultrasonic reaction device, it is pumped back to the material storage kettle.

[0156] After the reaction continues for 90 min, 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.

[0157] After the obtained third reaction solution is centrifuged and washed multiple times with a centrifuge, it is transferred to a dryer and dried at 120 °C for 6 h to obtain an iron manganese oxalate precursor. Example 3

[0158] The continuous reaction system shown in Fig. 1 is adopted to produce the iron manganese oxalate precursor.

[0159] Ferrous sulfate as a water-soluble divalent manganese salt, ferrous sulfate as a water-soluble divalent iron salt, sodium gluconate 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 10 wt%. Oxalic acid as a precipitating agent and deionized water are added to the second material dissolving kettle to prepare a precipitating agent solution with a concentration of 0.5 mol / L.

[0160] 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 material storage kettle, and the stirring speed of each kettle in the reaction process is 300 r / min. The reaction temperatures of the first reaction kettle and the material storage kettle are both controlled at room temperature (25 °C), the reaction temperature of the second reaction kettle is controlled at 50 °C, and the frequency of the ultrasonic reaction device is 50 KHz.

[0161] The metal salt solution and the precipitating agent solution are continuously conveyed from the first material dissolving kettle and the second material dissolving kettle to the first reaction kettle through two liquid supply pipes, mixed and reacted to produce the first reaction solution, and the flow rates of the metal salt solution and the precipitating agent solution are both 3 L / min.

[0162] After reacting for 20 min, 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 to the second reaction kettle to continue the reaction and produce the second reaction solution.

[0163] After the reaction continues for 60 min, 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 to the material storage kettle to continue the reaction and produce the third reaction solution.

[0164] The third reaction solution in the material storage kettle is continuously pumped to the ultrasonic reactor through the circulation pipeline and the circulation pump, and after the iron manganese oxalate precursor particles in the third reaction solution are refined by the ultrasonic cavitation action of the ultrasonic reactor, it is pumped back to the material storage kettle again.

[0165] After the reaction continues for 60 minutes, 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.

[0166] After the obtained third reaction solution is centrifuged and washed multiple times with a centrifuge, it is transferred to a dryer and dried at 120°C for 6 hours to obtain an iron manganese oxalate precursor. Example 4

[0167] An iron manganese oxalate precursor is produced by adopting the continuous reaction system shown in Figure 1.

[0168] Manganous acetate as a water-soluble divalent manganese salt, ferrous acetate as a water-soluble divalent iron salt, cobaltic acetate as a water-soluble divalent cobalt salt, sodium citrate 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 1 mol / L. In the prepared metal salt solution, the molar ratio of divalent manganese ions, divalent iron ions and divalent cobalt ions is 6.9:3:0.1, and the mass concentration of the complexing agent is 5 wt%. Ammonium oxalate as a precipitant, oxalic acid and deionized water are added to the second material dissolving kettle to prepare a precipitant solution with a concentration of 1 mol / L, and the molar ratio of ammonium oxalate to oxalic acid is 1:1.

[0169] As shown in Figure 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 material storage kettle, and the stirring speed of each kettle in the reaction process is 400 r / min. The reaction temperatures of the first reaction kettle and the material storage kettle are both controlled at room temperature (25°C), the reaction temperature of the second reaction kettle is controlled at 60°C, and the frequency of the ultrasonic reactor is 40 KHz.

[0170] The metal salt solution and the precipitant solution are continuously conveyed from the first material dissolving kettle and the second material dissolving kettle to the first reaction kettle respectively through two liquid supply pipes, mixed and reacted to generate a first reaction solution, and the flow rates of the metal salt solution and the precipitant solution are both 4 L / min.

[0171] After reacting for 15 minutes, 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 a second reaction solution.

[0172] After the reaction continues for 45 minutes, 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 material storage kettle to continue the reaction and generate a third reaction solution.

[0173] The third reaction solution in the material storage kettle is continuously pumped to the ultrasonic reaction device through the circulation pipeline and the circulation pump, and after the iron manganese oxalate precursor particles in the third reaction solution are refined by the ultrasonic cavitation effect of the ultrasonic reaction device, it is pumped back to the material storage kettle.

[0174] After the reaction continues for 45 minutes, 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.

[0175] After the obtained third reaction solution is centrifuged and washed multiple times with a centrifuge, it is transferred to a dryer and dried at 120°C for 6 hours to obtain an iron manganese oxalate precursor. Example 5

[0176] The method for producing the iron manganese oxalate precursor is the same as that in Example 1, and the difference is that no complexing agent is added. Comparative Example 1

[0177] Mix ferrous chloride as the water-soluble divalent manganese salt, ferrous chloride as the water-soluble divalent iron salt, and deionized water 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 to divalent iron ions is 7:3. Mix oxalic acid as the precipitant and deionized water to prepare a precipitant solution with a concentration of 1 mol / L.

[0178] Inject the metal salt solution and the precipitant solution into the reaction kettle simultaneously, start rapid stirring, the stirring speed is 400 r / min, control the reaction temperature at 60 °C, the reaction time is 40 min, and after the reaction is completed, naturally cool to room temperature to obtain a paste. After the obtained paste is derived from the discharge port at the bottom of the reaction kettle, centrifuge and wash it multiple times with a centrifuge, and then transfer it to a dryer and dry it at 120 °C for 6 h to obtain a manganese iron oxalate precursor. Comparative Example 2

[0179] Mix ferrous chloride as the water-soluble divalent manganese salt, ferrous chloride as the water-soluble divalent iron salt, sodium ethylenediaminetetramethylenephosphate as the complexing agent, and deionized water 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 to divalent iron ions is 7:3, and the mass concentration of the complexing agent is 5 wt%. Mix oxalic acid as the precipitant and deionized water to prepare a precipitant solution with a concentration of 1 mol / L.

[0180] Inject the metal salt solution and the precipitant solution into the reaction kettle simultaneously, start rapid stirring, the stirring speed is 400 r / min, control the reaction temperature at 60 °C, the reaction time is 40 min, and after the reaction is completed, naturally cool to room temperature to obtain a paste. After the obtained paste is derived from the discharge port at the bottom of the reaction kettle, centrifuge and wash it multiple times with a centrifuge, and then transfer it to a dryer and dry it at 120 °C for 6 h to obtain a manganese iron oxalate precursor. Comparative Example 3

[0181] Mix ferrous chloride as a water-soluble divalent manganese salt, ferrous chloride as a water-soluble divalent iron salt, and deionized water 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 to divalent iron ions is 7:3. Mix oxalic acid as a precipitant and deionized water to prepare a precipitant solution with a concentration of 1 mol / L.

[0182] Simultaneously inject the metal salt solution and the precipitant solution into a reaction kettle, start rapid stirring, with a stirring speed of 400 r / min, control the reaction temperature at 60 °C, the reaction time is 40 min, and after the reaction is completed, naturally cool to room temperature to obtain a paste. After the obtained paste is led out from the discharge port at the bottom of the reaction kettle, it is introduced into an ultrasonic reactor for micronization treatment, reacted for 30 min, then centrifuged and washed multiple times with a centrifuge, transferred to a dryer and dried at 120 °C for 6 h to obtain a manganese iron oxalate precursor. Test section (1) Particle size measurement

[0183] Use a Malvern Master Size 3000 laser particle size distribution analyzer to measure the volume-based particle size distribution of the manganese iron oxalate precursor manufactured above. Dv50 and Dv90 are the corresponding particle sizes when the cumulative volume distribution percentage of the material reaches 50% and 90%. Refer to GB / T19077-2016 as the basis for measurement. (2) Measurement of Mn / Fe molar ratio

[0184] Use a Plasma 3000 inductively coupled plasma optical emission spectrometer to measure the contents of manganese and iron elements in the manganese iron oxalate precursor manufactured above by ICP-OES method, and calculate their molar ratio.

[0185]

Table 1

[0186] Figure 2 is a scanning electron microscope (SEM) image of the iron manganese oxalate precursor produced in Example 1. The magnification of Figure 2(a) is 20,000 times, and the magnification of Figure 2(b) is 50,000 times. Figure 3 is a scanning electron microscope (SEM) image of the iron manganese oxalate precursor produced in Comparative Example 3 at a magnification of 5,000 times. Figure 4 is an X-ray diffraction spectrum (XRD) image of the iron manganese oxalate precursor produced in Example 1.

[0187] As can be seen from the comprehensive measurement results in Table 1 and Figure 2, the iron manganese oxalate precursor produced by the continuous manufacturing method provided in the present application has the advantages of small particle size, narrow particle size distribution, uniform element distribution, and regular shape.

[0188] As can be seen from the comprehensive measurement results in Table 1 and Figure 3, the iron manganese oxalate precursor produced by the conventional batch manufacturing method has a large particle size, a wide particle size distribution, and a non-uniform element distribution.

[0189] As can be further seen from Figure 4, the iron manganese oxalate precursor produced by the continuous manufacturing method provided in the present application further has the advantages of high purity and high crystallinity.

[0190] As can be seen from the comprehensive measurement results of Example 1 and Comparative Example 2, and Example 5 and Comparative Example 1, the molar ratio of Mn / Fe in the iron manganese oxalate precursor particles produced by the continuous manufacturing method provided in the present application and the molar ratio of Mn / Fe in the metal salt solution have a smaller difference, thereby enabling accurate control of the manganese element and iron element contents.

[0191] As can be further seen from the comprehensive measurement results of Example 1 and Comparative Example 2, and Example 5 and Comparative Example 1, when a complexing agent is added to the first material dissolution kettle, it helps to more accurately control the contents of the manganese element and iron element in the produced iron manganese oxalate precursor particles.

[0192] Note that this application is not limited to the above embodiments. The above embodiments are merely examples, and any embodiments that have substantially the same configuration as the technical idea and exhibit 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 and added to the embodiments, as well as other forms constructed by combining some components in the embodiments, are also included in the scope of this application.

Explanation of Reference Numerals

[0193] 1 First material dissolving kettle 2 Second material dissolving kettle 3 First reaction kettle 4 Second reaction kettle 5 Material storage kettle 6 Ultrasonic reaction device 7 First supply port 8 First overflow port 9 First discharge port 10 Second discharge port 11 Second supply port 12 Second overflow port 13 Third supply port 14 Fourth supply port 15 Third discharge port 16 Third overflow port 17 Circulation pump 18 First metering pump 19 Second metering pump 20 Cooling water circulation pipeline 21 First shut-off valve 22 Second shut-off valve 23 Third shut-off valve 24 Fourth shut-off valve 25 Fifth shut-off valve

Claims

A manufacturing method for producing an iron manganese oxalate precursor through a continuous reaction system, comprising: The continuous reaction system includes a first material dissolving kettle, a second material dissolving kettle, a first reaction kettle, a second reaction kettle, a material storage kettle, and an ultrasonic reaction device; The first material dissolving kettle is used to contain a metal salt solution necessary for producing the iron manganese oxalate precursor, and the second material dissolving kettle is used to contain a precipitant solution necessary for producing the iron manganese oxalate 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 discharge port of the first material dissolving kettle and the second discharge port of the second material dissolving kettle respectively through two pipelines. Thereby, the first reaction kettle contains and mixes the metal salt solution and the precipitant solution and then reacts them to generate a first reaction 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 through a 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 material storage kettle includes a third supply port, a fourth supply port, a third discharge port, and a third overflow port. The third supply port of the material storage kettle communicates with the second overflow port of the second reaction kettle through a pipeline. Thereby, the material storage kettle contains the second reaction solution from the second reaction kettle and continuously reacts it to generate a third reaction solution. The third discharge port and the fourth supply port of the material storage kettle are in circular communication with the ultrasonic reaction device through a circulation pipeline and a circulation pump. Thereby, the third reaction solution in the material storage kettle is refined by the action of ultrasonic cavitation; When the liquid level of the third reaction solution is higher than the third overflow port of the material storage kettle, the third reaction solution flows out through the third overflow port of the material storage kettle; The manufacturing method at least includes: Step S1 of adding a metal salt solution necessary for producing the iron manganese oxalate precursor to the first reaction kettle and adding a precipitant solution necessary for producing the iron manganese oxalate precursor to the second material dissolving kettle; The metal salt solution in the first material dissolving kettle and the precipitant solution in the second material dissolving kettle are respectively transported to the first reaction kettle through different pipelines, mixed and then reacted to generate a first reaction solution. When the liquid level of the first reaction solution is higher than the overflow port of the first reaction kettle, the first reaction solution is automatically transported to the second reaction kettle, and then the reaction is continued to generate a second reaction solution. When the liquid level of the second reaction solution is higher than the overflow port of the second reaction kettle, the second reaction solution is automatically transported to the material storage kettle, and the reaction is continued to generate a third reaction solution. At the same time, the third reaction solution is pumped to the ultrasonic reaction device through a circulation pipeline and a circulation pump, and the crystal grains in the third reaction solution are refined by the action of ultrasonic cavitation of the ultrasonic reaction device and then pumped back to the material storage kettle again. When the liquid level of the third reaction solution is higher than the overflow port of the material storage kettle, the third reaction solution automatically flows out through the overflow port of the material storage kettle. In the reaction process, the first material dissolving kettle, the second material dissolving kettle, the first reaction kettle, the second reaction kettle and the material storage kettle are all under a protective gas atmosphere and each kettle maintains a stirring state, step S2, Step S3 of obtaining a manganese iron oxalate precursor by centrifuging, washing and drying the third reaction solution obtained from the overflow port of the material storage kettle, including, The reaction temperature of the first reaction kettle is lower than that of the second reaction kettle, and the reaction temperature of the material storage kettle is lower than that of the second reaction kettle, The metal salt includes a water-soluble divalent iron salt and a water-soluble divalent manganese salt, The precipitant includes one or more of oxalic acid and water-soluble oxalates, A method for producing a manganese iron oxalate precursor.

2. The continuous reaction system further includes a first metering pump and a second metering pump. Both ends of the first metering pump communicate with the first discharge port of the first material dissolving kettle and the first supply port of the first reaction kettle through pipelines respectively, thereby adjusting the flow rate of the metal salt solution. Both ends of the second metering pump communicate with the second discharge port of the second material dissolving kettle and the first supply port of the first reaction kettle through pipelines respectively, thereby adjusting the flow rate of the precipitant solution. The manufacturing method according to claim 1.

3. The continuous reaction system further includes a cooling water circulation pipeline installed outside the ultrasonic reaction device. The manufacturing method according to claim 1.

4. A complexing agent is further added to the first material dissolving kettle. The manufacturing method according to claim 1.

5. The manufacturing method according to claim 4, wherein the complexing agent contains one or more of aminocarboxylates, hydroxycarboxylates, and organic phosphonates.

6. The manufacturing method according to claim 5, wherein the complexing agent contains one or more of sodium ethylenediaminetetramethylenephosphate, sodium ethylenediaminetetraacetate, sodium gluconate, and sodium citrate.

7. The reaction temperature of the first reaction kettle is 20°C to 30°C, and / or The reaction temperature of the second reaction kettle is 40°C to 90°C, and / or The reaction temperature of the material storage kettle is 20°C to 30°C, for the manufacturing method according to claim 1.

8. The flow rate of the metal salt solution is 0.5 L / min to 6 L / min, and / or The flow rate of the precipitating agent solution is 0.5 L / min to 6 L / min, and / or The flow rates of the metal salt solution and the precipitating agent solution are the same, for the manufacturing method according to claim 1.

9. The residence time in the first reaction kettle during the growth process of the iron manganese oxalate precursor is 10 min to 2 h, and / or The residence time in the second reaction kettle during the growth process of the iron manganese oxalate precursor is 10 min to 10 h, and / or The residence time in the material storage kettle during the growth process of the iron manganese oxalate precursor is 10 min to 10 h, for the manufacturing method according to claim 1.

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 material storage kettle, and / or The volumes of the second reaction kettle and the material storage kettle are the same, for the manufacturing method according to claim 1.

11. The frequency of the ultrasonic reaction device is 15 kHz to 60 kHz, for the manufacturing method according to claim 1.

12. The metal salt further contains a divalent salt of the water-soluble doping element M, where M represents the doping element for the manganese site and the iron site, and contains one or more of Co, Mg, Zn, Ca, Ti, V, Ni, and Cr, for the manufacturing method according to claim 1.

13. (1) The water-soluble divalent iron salt contains one or more of ferrous chloride, ferrous bromide, ferrous nitrate, ferrous sulfate, ferrous acetate, ferrous fluosilicate, and ferrous perchlorate, (2) The water-soluble divalent manganese salt contains one or more of manganese(I) chloride, manganese(I) bromide, manganese(I) nitrate, manganese(I) sulfate, manganese(I) acetate, and manganese(I) perchlorate, and (3) The divalent 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, The manufacturing method according to claim 12, including one or more of them.

14. The water-soluble oxalate according to claim 1, wherein the manufacturing method includes one or more of lithium oxalate, sodium oxalate, potassium oxalate, and ammonium oxalate.

15. The concentration of the metal salt solution is 0.5 mol / L to 2 mol / L, and / or The concentration of the precipitant solution is 0.5 mol / L to 2 mol / L, and / or The molar ratio of the metal salt to the precipitant is 1:1 to 1:5, according to the manufacturing method of claim 1.

16. The stirring speed of the first material dissolution tank is 300 r / min to 600 r / min, and / or The stirring speed of the second material dissolution tank is 300 r / min to 600 r / min, and / or The stirring speed of the first reaction tank is 300 r / min to 600 r / min, and / or The stirring speed of the second reaction tank is 300 r / min to 600 r / min, and / or The stirring speed of the material storage tank is 300 r / min to 600 r / min, according to the manufacturing method of claim 1.

17. The protective gas includes nitrogen gas, an inert gas, or a combination thereof, according to the manufacturing method of claim 1.

18. The iron manganese oxalate precursor has the chemical formula Fe ｘ Mn ｙ M １－ｘ－ｙ C ２ O ４ ・2H ２ O, where 0 < x < 1, 0 < y < 1, 0 ≦ 1 - x - y < 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, and Cr, and the iron manganese oxalate precursor is electrically neutral. The manufacturing method according to claim 1.

19. The volume-based particle size distributions Dv90 and Dv50 satisfy 1 < Dv90 / Dv50 ≤ 2, and / or The volume-based particle size distribution Dv50 is 200 nm to 600 nm, and / or The volume-based particle size distribution Dv90 is 260 nm to 800 nm, according to the manufacturing method of claim 18.

20. A manufacturing method for producing lithium iron manganese phosphate, after performing the manufacturing method according to any one of claims 1 to 19, at least The step S10 of uniformly mixing the produced iron manganese oxalate precursor with a lithium source, a phosphorus source, an optionally added doping element N source, an optionally added doping element Q source, and an optionally added doping element R source at a preset ratio to obtain a mixed raw material, where N represents a doping element for lithium sites and includes one or more of Zn, Al, Na, K, Mg, Nb, Mo, and W; Q represents a doping element for phosphorus sites and includes one or more of B, S, Si, and N; and R represents a doping element for oxygen sites and includes one or more of S, F, Cl, and Br. By sintering the mixed raw material obtained in step S10, 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, and 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, A method for producing lithium iron manganese phosphate, comprising the above.

21. The production method according to claim 20, wherein in step S10, a carbon source is further added to the mixed raw material.

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