Ferric manganese oxalate, lithium manganese iron phosphate, preparation methods of ferric manganese oxalate and lithium manganese iron phosphate, and positive pole piece, battery and electric device comprising ferric manganese oxalate and lithium manganese iron phosphate

Abstract

The invention discloses ferromanganese oxalate, lithium ferromanganese phosphate, a preparation method of the ferromanganese oxalate and the lithium ferromanganese phosphate, and a positive pole piece, a battery and an electric device comprising the ferromanganese oxalate and the lithium ferromanganese phosphate, the preparation method of the ferromanganese oxalate comprises the following steps: adding manganese powder into an industrial manganese sulfate aqueous solution, and reacting under stirring and heating conditions to obtain a manganese sulfate suspension; filtering to obtain a refined manganese sulfate aqueous solution; uniformly mixing an iron source solid or an iron source aqueous solution with the refined manganese sulfate aqueous solution to obtain a manganese-iron mixed metal salt solution; adding the obtained manganese-iron mixed metal salt solution into a precipitant aqueous solution for reaction; and after the ferromanganese mixed metal salt solution is fed, adding an alkaline pH regulator for continuous reaction to obtain a ferromanganese oxalate suspension, and then filtering, washing and drying to obtain a ferromanganese oxalate solid. The preparation method of the oxalate ferromanganese provided by the invention is simple in process, low in cost, great in environmental protection advantage and easy for industrial production.

Description

Technical Field

[0001] The present application relates to manganese iron oxalate, lithium manganese iron phosphate, a preparation method thereof, and a positive electrode sheet, a battery and an electrical device containing the same. Background Art

[0002] In recent years, batteries have been widely used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields. With the application and promotion of batteries, their safety performance has received increasing attention. Lithium manganese iron phosphate has become one of the most popular positive electrode active materials due to its advantages such as high capacity, good safety performance and abundant raw material sources. Manganese iron oxalate is widely used as a precursor for lithium manganese iron phosphate due to its low cost. Industrial manganese sulfate is widely used as a raw material for manganese iron oxalate due to its advantages of easy availability of raw materials, large market reserves and high cost performance. However, the impurity ion content of industrial manganese sulfate is usually very high, and the impurity ion content of manganese iron oxalate prepared therefrom is high. The high content of impurity ions will affect the performance of the prepared lithium manganese iron phosphate and batteries. The above statements are only used to provide background technical information related to this application and do not necessarily constitute prior art. Summary of the Invention

[0003] The present application provides manganese iron oxalate, lithium manganese iron phosphate, their preparation methods, and positive electrode plates, batteries and electrical devices containing the same. The preparation method of manganese iron oxalate provided in the present application has a simple process, low cost, great environmental advantages, and is easy to industrialize. Battery-grade manganese iron oxalate with a low impurity content can be directly prepared using industrial manganese sulfate as a raw material.

[0004] In a first aspect, the present application provides a method for preparing ferromanganese oxalate, comprising the following steps: providing an industrial manganese sulfate aqueous solution; adding manganese powder to the industrial manganese sulfate aqueous solution, reacting under stirring and heating conditions to obtain a manganese sulfate suspension, wherein the pH of the obtained manganese sulfate suspension is controlled between 4 and 8, and then filtering to obtain a refined manganese sulfate aqueous solution; uniformly mixing an iron source solid or an iron source aqueous solution with the refined manganese sulfate aqueous solution to obtain a manganese-iron mixed metal salt solution; adding the obtained manganese-iron mixed metal salt solution to a precipitant aqueous solution for reaction, wherein the precipitant includes one or more of oxalic acid and oxalate; after the feeding of the manganese-iron mixed metal salt solution is completed, adding an alkaline pH adjuster to continue the reaction to obtain a manganese-iron oxalate suspension, and then filtering, washing, and drying to obtain a manganese-iron oxalate solid.

[0005] Manganese powder reacts with water under stirring and heating conditions to produce manganous hydroxide. When the pH of the resulting manganese sulfate suspension is between 4 and 8, the manganous hydroxide does not precipitate, but rather dissociates into divalent manganese ions and hydroxide ions in the manganese sulfate suspension. The continuously dissociated hydroxide ions increase the pH of the manganese sulfate suspension, allowing impurity ions in the industrial manganese sulfate, such as aluminum ions, copper ions, and zinc ions, to precipitate with the hydroxide ions. Subsequently, filtration yields a refined manganese sulfate aqueous solution with reduced impurity ion content, thereby reducing the impurity content of the prepared ferromanganese oxalate solid.

[0006] In the preparation method provided in the examples of the present application, a ferromanganese mixed metal salt solution is added to an aqueous precipitant solution to carry out a precipitation reaction. In this case, the impurity ion content in the reaction system is low. During the precipitation reaction, the probability of impurity ions, such as calcium and magnesium ions, entering the ferromanganese oxalate crystals is reduced, thereby reducing the calcium and magnesium impurity content of the prepared ferromanganese oxalate solid.

[0007] After the feeding of the ferromanganese mixed metal salt solution is completed, an alkaline pH regulator is added. The alkaline pH regulator can promote the dissociation of the precipitant to produce oxalate ions, thereby promoting the precipitation of ferromanganese.

[0008] The preparation method provided in the embodiments of the present application has simple process, low cost, great environmental advantages, and is easy to industrialize. It can directly use industrial manganese sulfate as a raw material to prepare battery-grade ferromanganese oxalate with a low impurity content.

[0009] In some embodiments, the pH of the obtained manganese sulfate suspension is controlled between 7 and 7.8, thereby better precipitating impurity ions in industrial manganese sulfate and further reducing the impurity content of the prepared ferromanganese oxalate solid.

[0010] In some embodiments, in the step of adding manganese powder to an industrial manganese sulfate aqueous solution and reacting under stirring and heating conditions to obtain a manganese sulfate suspension, the mass fraction of the industrial manganese sulfate aqueous solution is 10%-40%.

[0011] In some embodiments, in the step of adding manganese powder to an industrial manganese sulfate aqueous solution and reacting under stirring and heating conditions to obtain a manganese sulfate suspension, the mass of the manganese powder is 0.1%-5% of the mass of the industrial manganese sulfate in the industrial manganese sulfate aqueous solution.

[0012] In some embodiments, in the step of adding manganese powder to an industrial manganese sulfate aqueous solution and reacting under stirring and heating conditions to obtain a manganese sulfate suspension, the purity of the manganese powder is greater than or equal to 99%.

[0013] In some embodiments, in the step of adding manganese powder to an industrial manganese sulfate aqueous solution and reacting under stirring and heating conditions to obtain a manganese sulfate suspension, the heating temperature is 40° C.-80° C.

[0014] In some embodiments, the iron source solid or the iron source aqueous solution is uniformly mixed with the refined manganese sulfate aqueous solution, and the mass fraction of the obtained manganese and iron mixed metal salt solution is 10% to 30%.

[0015] In some embodiments, in the step of adding the obtained manganese-iron mixed metal salt solution to a precipitant aqueous solution for reaction, the ratio of the molar amount of the precipitant in the precipitant aqueous solution to the sum of the molar amounts of manganese and iron elements in the manganese-iron mixed metal salt solution is (2.2-1.0):1.

[0016] In some embodiments, in the step of adding the obtained manganese-iron mixed metal salt solution to the precipitant aqueous solution for reaction, the reaction temperature is 20°C-90°C.

[0017] In some embodiments, in the step of adding the obtained manganese-iron mixed metal salt solution to a precipitant aqueous solution for reaction, the mass fraction of the precipitant aqueous solution is 5.0%-30.0%, optionally 6.0%-16.0%.

[0018] In some embodiments, in the step of adding the obtained ferromanganese mixed metal salt solution to the precipitant aqueous solution for reaction, the feeding rate of the ferromanganese mixed metal salt solution is 10 mL / min-100 mL / min, and optionally 20 mL / min-70 mL / min. A slower feeding rate is beneficial to the growth of ferromanganese oxalate grains, resulting in larger ferromanganese oxalate solid particles, thereby improving the filtration and washing effect of impurities adsorbed on the surface of the ferromanganese oxalate crystals.

[0019] In some embodiments, after the feeding of the manganese-iron mixed metal salt solution is completed, an alkaline pH regulator is added to continue the reaction to obtain a manganese-iron oxalate suspension, wherein the alkaline pH regulator includes a mixture of one or more of ammonia water, sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, barium hydroxide aqueous solution, and lithium hydroxide aqueous solution.

[0020] In some embodiments, after the feeding of the ferromanganese mixed metal salt solution is completed, an alkaline pH regulator is added to continue the reaction to obtain a ferromanganese oxalate suspension, and the mass fraction of the alkaline pH regulator is 10%-25%.

[0021] In some embodiments, after the feeding of the manganese-iron mixed metal salt solution is completed, an alkaline pH regulator is added to continue the reaction to obtain a manganese-iron oxalate suspension, and the pH value of the alkaline pH regulator is 11-13.

[0022] In some embodiments, after the feeding of the manganese-iron mixed metal salt solution is completed, an alkaline pH regulator is added to continue the reaction to obtain a manganese-iron oxalate suspension, and the feeding rate of the alkaline pH regulator is 10 mL / min-100 mL / min.

[0023] In some embodiments, after the feeding of the manganese-iron mixed metal salt solution is completed, an alkaline pH regulator is added to continue the reaction to obtain a manganese-iron oxalate suspension, and the reaction temperature is 20°C-90°C.

[0024] In some embodiments, after the feeding of the manganese-iron mixed metal salt solution is completed, an alkaline pH regulator is added to continue the reaction. In the step of obtaining a manganese-iron oxalate suspension, an alkaline pH regulator is added to continue the reaction until the pH value of the reaction system reaches 2-4, the feeding is stopped, and the reaction is stirred for 20 min-60 min.

[0025] In some embodiments, the method for providing an industrial manganese sulfate aqueous solution comprises the following steps: dissolving industrial manganese sulfate in water, stirring until completely dissolved, and filtering to obtain the industrial manganese sulfate aqueous solution.

[0026] In some embodiments, in the step of uniformly mixing an iron source solid or an iron source aqueous solution with a refined manganese sulfate aqueous solution to obtain a manganese-iron mixed metal salt solution, the iron source comprises one or more of ferrous sulfate, ferrous nitrate, ferrous chloride, and ferrous acetate.

[0027] In some embodiments, in the step of uniformly mixing an iron source solid or an iron source aqueous solution with a refined manganese sulfate aqueous solution to obtain a manganese-iron mixed metal salt solution, the molar ratio of manganese to iron in the manganese-iron mixed metal salt solution is 5:5-8:2.

[0028] In a second aspect, the present application provides a manganese iron oxalate prepared by the preparation method of the first aspect of the present application.

[0029] In a third aspect, the present application provides a method for preparing lithium manganese iron phosphate, comprising the following steps: using a material obtained by mixing manganese iron oxalate prepared by the preparation method of the first aspect of the present application with a lithium source, a phosphorus source, and a carbon source as a raw material, and obtaining lithium manganese iron phosphate through sintering treatment.

[0030] In some embodiments, one or more of a source of doping element M, a source of doping element N, a source of doping element Q, and a source of doping element R are also added to the mixed material, where M represents a doping element at the manganese position and the iron position, N represents a doping element at the lithium position, Q represents a doping element at the phosphorus position, and R represents a doping element at the oxygen position.

[0031] In a fourth aspect, the present application provides a lithium manganese iron phosphate prepared by the preparation method of the third aspect of the present application.

[0032] In a fifth aspect, the present application provides a positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer located on at least one surface of the positive electrode current collector, wherein the positive electrode film layer comprises lithium manganese iron phosphate prepared by the preparation method of the third aspect of the present application. In a sixth aspect, the present application provides a battery comprising the positive electrode sheet of the fifth aspect of the present application.

[0033] In a seventh aspect, the present application provides an electrical device comprising the battery according to the sixth aspect of the present application, wherein the battery is used to provide electrical energy.

[0034] The electric device of the present application includes the battery provided by the present application, and thus has at least the same advantages as the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] To more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on the drawings without inventive effort.

[0036] Figure 1 is a schematic diagram of a battery cell provided in some embodiments of the present application.

[0037] Figure 2 is a schematic diagram of a battery module provided in some embodiments of the present application.

[0038] Figure 3 is a schematic diagram of a battery pack provided in some embodiments of the present application.

[0039] Figure 4 yes Figure 3 Schematic diagram of the battery pack shown.

[0040] Figure 5 This is a schematic diagram of an exploded view of a battery cell provided in some embodiments of the present application.

[0041] Figure 6 This is a schematic diagram of an electrical device provided in some embodiments of the present application.

[0042] In the accompanying drawings, the drawings are not necessarily drawn to scale.

[0043] The description of the accompanying figures is as follows: 1. battery pack; 2. upper box; 3. lower box; 4. battery module; 5. battery cell; 51. shell; 52. electrode assembly; 53. cover plate. DETAILED DESCRIPTION

[0044] Hereinafter, the embodiments of the manganese iron oxalate, lithium manganese iron phosphate, preparation methods thereof, and positive electrode sheets, batteries, and electrical devices containing the same will be described in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, 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.

[0045] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0046] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present application.

[0047] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form new technical solutions, and such technical solutions should be deemed to be included in the disclosure of this application.

[0048] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0049] In this application, the terms "plurality" and "multiple" refer to two or more.

[0050] Unless otherwise specified, the terms used in this application have the common meanings that are commonly understood by those skilled in the art.

[0051] Unless otherwise stated, the numerical values ​​of the various parameters mentioned in this application can be measured using various test methods commonly used in the art, for example, they can be measured according to the test methods given in the examples of this application. Unless otherwise stated, the test temperature of each parameter is 25°C.

[0052] The battery mentioned in the embodiments of the present application may be a single physical module including one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in the present application may include a battery cell, a battery module, or a battery pack.

[0053] A battery cell is the smallest unit that makes up a battery and can independently realize the function of charging and discharging. A battery cell can be cylindrical, rectangular or other shapes, etc., which is not limited in the embodiments of the present application. Figure 1 As an example, a battery cell 5 having a rectangular parallelepiped structure is shown.

[0054] When there are multiple battery cells, the multiple battery cells are connected in series, in parallel, or in mixed series via a busbar. In some embodiments, the battery may be a battery module; when there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module. In some embodiments, the battery may be a battery pack, which includes a housing and battery cells, with the battery cells or battery modules housed in the housing. In some embodiments, the housing may serve as part of the vehicle's chassis structure. For example, a portion of the housing may form at least a portion of the vehicle's floor, or a portion of the housing may form at least a portion of the vehicle's crossbeam or longitudinal beam.

[0055] In some embodiments, the battery may be an energy storage device, including an energy storage container, an energy storage cabinet, and the like.

[0056] In some embodiments, battery cells may be assembled into a battery module. A battery module may contain multiple battery cells, and the specific number may be adjusted according to the application and capacity of the battery module. Figure 2 FIG. 4 is a schematic diagram of a battery module 4 as an example. Figure 2 As shown, in the battery module 4, the plurality of battery cells 5 can be arranged in sequence along the length direction of the battery module 4. Of course, they can also be arranged in any other manner. Further, the plurality of battery cells 5 can be fixed by fasteners.

[0057] Optionally, the battery module 4 may further include a housing having an accommodation space, and the plurality of battery cells 5 are accommodated in the accommodation space.

[0058] In some embodiments, the battery modules described above may also be assembled into a battery pack, and the number of battery modules contained in the battery pack may be adjusted according to the application and capacity of the battery pack.

[0059] Figure 3 and Figure 4 FIG. 1 is a schematic diagram of a battery pack 1 as an example. Figure 3 and Figure 4 As shown, a battery pack 1 may include a housing and multiple battery modules 4 disposed therein. The housing comprises an upper housing 2 and a lower housing 3. The upper housing 2 covers the lower housing 3 and forms an enclosed space for accommodating the battery modules 4. The multiple battery modules 4 may be arranged in any manner within the housing.

[0060] The battery cells provided in the embodiments of the present application may include lithium-ion battery cells, lithium metal battery cells, negative electrode-free lithium metal battery cells, etc.

[0061] The battery cell includes an electrode assembly and an electrolyte. The electrode assembly can be a wound structure or a laminated structure, which is not limited in the present embodiment.

[0062] The battery cell may also include an outer packaging, which can be used to encapsulate the electrode assembly and electrolyte. The outer packaging can be a hard shell, such as a hard plastic shell, aluminum shell, steel shell, etc. The outer packaging can also be a soft package, such as a pouch-type soft package. The soft package can be made of plastic, such as one or more of polypropylene, polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0063] In some embodiments, as Figure 5As shown, the outer packaging may include a housing 51 and a cover plate 53. The housing 51 may include a base plate and side plates connected to the base plate, which together form a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 is used to cover the opening, thereby sealing the receiving cavity. The electrode assembly 52 is enclosed in the receiving cavity. The number of electrode assemblies 52 contained in a battery cell 5 can be one or more, and can be adjusted according to needs.

[0064] Industrial manganese sulfate contains a large number of impurities, such as calcium, magnesium, aluminum, copper, and zinc, which can negatively impact battery capacity and cycle performance. Therefore, industrial manganese sulfate cannot typically be used directly as a battery raw material. Instead, it must first be purified to produce battery-grade manganese sulfate, which increases battery production costs.

[0065] The embodiments of the present application provide a method for preparing ferromanganese oxalate, which can directly prepare battery-grade ferromanganese oxalate using industrial manganese sulfate as a raw material.

[0066] The preparation method comprises the following steps: providing an industrial manganese sulfate aqueous solution; adding manganese powder to the industrial manganese sulfate aqueous solution, reacting under stirring and heating conditions to obtain a manganese sulfate suspension, wherein the pH of the obtained manganese sulfate suspension is controlled between 4 and 8, and then filtering to obtain a refined manganese sulfate aqueous solution; uniformly mixing an iron source solid or an iron source aqueous solution with the refined manganese sulfate aqueous solution to obtain a manganese-iron mixed metal salt solution; adding the obtained manganese-iron mixed metal salt solution to a precipitant aqueous solution for reaction, wherein the precipitant comprises one or more of oxalic acid and oxalate; after the manganese-iron mixed metal salt solution is fed, adding an alkaline pH regulator to continue the reaction to obtain a manganese-iron oxalate suspension, and then filtering, washing, and drying to obtain a manganese-iron oxalate solid.

[0067] Manganese powder reacts with water under stirring and heating conditions to produce manganous hydroxide. When the pH of the resulting manganese sulfate suspension is between 4 and 8, the manganous hydroxide does not precipitate, but rather dissociates into divalent manganese ions and hydroxide ions in the manganese sulfate suspension. The continuously dissociated hydroxide ions increase the pH of the manganese sulfate suspension, allowing impurity ions in the industrial manganese sulfate, such as aluminum ions, copper ions, and zinc ions, to precipitate with the hydroxide ions. Subsequently, filtration yields a refined manganese sulfate aqueous solution with reduced impurity ion content, thereby reducing the impurity content of the prepared ferromanganese oxalate solid.

[0068] In the preparation method provided in the examples of the present application, a ferromanganese mixed metal salt solution is added to an aqueous precipitant solution to carry out a precipitation reaction. In this case, the impurity ion content in the reaction system is low. During the precipitation reaction, the probability of impurity ions, such as calcium and magnesium ions, entering the ferromanganese oxalate crystals is reduced, thereby reducing the calcium and magnesium impurity content of the prepared ferromanganese oxalate solid.

[0069] After the feeding of the ferromanganese mixed metal salt solution is completed, an alkaline pH regulator is added. The alkaline pH regulator can promote the dissociation of the precipitant to produce oxalate ions, thereby promoting the precipitation of ferromanganese.

[0070] The preparation method provided in the embodiments of the present application has simple process, low cost, great environmental advantages, and is easy to industrialize. It can directly use industrial manganese sulfate as a raw material to prepare battery-grade ferromanganese oxalate with a low impurity content.

[0071] Optionally, the pH of the obtained manganese sulfate suspension is controlled between 6 and 7.8. More preferably, the pH of the obtained manganese sulfate suspension can be controlled between 7 and 7.8. This can better precipitate impurity ions in industrial manganese sulfate, thereby further reducing the impurity content of the prepared ferromanganese oxalate solid.

[0072] In some embodiments, the method for providing an industrial manganese sulfate aqueous solution may include the following steps: dissolving industrial manganese sulfate in water, stirring until completely dissolved, and filtering to obtain the industrial manganese sulfate aqueous solution.

[0073] Alternatively, the water may be pure water.

[0074] Alternatively, the filtration may be vacuum filtration.

[0075] Optionally, the mass fraction of the provided industrial manganese sulfate aqueous solution can be 10%-40%, for example, 10%, 15%, 20%, 25%, 30%, 35%, 40%, or any range thereof. Optionally, the mass fraction of the provided industrial manganese sulfate aqueous solution can be 15%-30%.

[0076] Manganese powder reacts with water under stirring and heating conditions to produce manganous hydroxide. In some embodiments, in the step of adding manganese powder to an aqueous solution of industrial manganese sulfate and reacting under stirring and heating conditions to obtain a manganese sulfate suspension, the heating temperature can be 40°C to 80°C, for example, 40°C, 50°C, 60°C, 70°C, 80°C, or a range consisting of any of the foregoing values. In some embodiments, the stirring rate can be 400 rpm to 800 rpm.

[0077] In some embodiments, the mass of the manganese powder can be 0.1%-5% of the mass of the industrial manganese sulfate in the industrial manganese sulfate aqueous solution, for example, 0.1%, 0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any range thereof. Alternatively, the mass of the manganese powder can be 0.5%-5%, 0.8%-5%, 1%-5%, 1.5%-5%, 2%-5%, 1%-4%, 1.5%-4%, or 2%-4% of the mass of the industrial manganese sulfate in the industrial manganese sulfate aqueous solution.

[0078] Manganese powder reacts with water under stirring and heating conditions to produce manganous hydroxide. In addition, a slightly excess amount of manganese powder can undergo a replacement reaction with the impurity zinc ions in the solution, thereby further reducing the impurity zinc content in the prepared ferromanganese oxalate product.

[0079] Filtration can remove precipitates in the obtained manganese sulfate suspension, such as aluminum hydroxide, copper hydroxide, zinc hydroxide, etc., and can also remove excess manganese powder in the manganese sulfate suspension. Optionally, the filtration can be vacuum filtration.

[0080] In some embodiments, the purity of the manganese powder may be greater than or equal to 99%, and optionally greater than or equal to 99.9%.

[0081] In some embodiments, in the step of uniformly mixing an iron source solid or an iron source aqueous solution with a refined manganese sulfate aqueous solution to obtain a manganese-iron mixed metal salt solution, the iron source may include one or more of ferrous sulfate, ferrous nitrate, ferrous chloride, and ferrous acetate.

[0082] In some embodiments, in the step of uniformly mixing an iron source solid or an iron source aqueous solution with a refined manganese sulfate aqueous solution to obtain a manganese-iron mixed metal salt solution, the molar ratio of manganese element to iron element in the manganese-iron mixed metal salt solution can be 5:5-8:2, for example, 5:5, 6:4, 7:3, 8:2, or a range consisting of any of the above values.

[0083] The precipitant includes one or more of oxalic acid and oxalates. Alternatively, the oxalates may include one or more of sodium oxalate and ammonium oxalate. More preferably, the precipitant includes oxalic acid.

[0084] The method for preparing an aqueous oxalic acid solution comprises the following steps: dissolving oxalic acid in water and stirring until completely dissolved to obtain the aqueous oxalic acid solution. The water may be pure water. The temperature during the oxalic acid dissolution process may be 20°C to 90°C, optionally 40°C to 90°C or 60°C to 90°C. Heating can increase the solubility of oxalic acid in water.

[0085] In some embodiments, the mass fraction of the precipitant aqueous solution can be 5.0%-30.0%, for example, 5.0%, 6.0%, 8.0%, 10.0%, 12.0%, 14.0%, 16.0%, 18.0%, 20.0%, 22.0%, 24.0%, 26.0%, 28.0%, 30.0%, or any range thereof. Alternatively, the mass fraction of the precipitant aqueous solution can be 6.0%-24.0%, 6.0%-20.0%, 6.0%-16.0%, or 6.0%-12.0%.

[0086] In some embodiments, in the step of adding the obtained ferromanganese mixed metal salt solution to the precipitant aqueous solution for reaction, the reaction temperature may be 20°C-90°C, for example, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, or a range consisting of any of the foregoing values. Alternatively, the reaction temperature may be 40°C-90°C, or 60°C-90°C. The reaction under heating conditions can promote the dissociation of the precipitant to produce more oxalate ions, thereby promoting the precipitation of ferromanganese.

[0087] In some embodiments, in the step of adding the obtained manganese-iron mixed metal salt solution to the precipitant aqueous solution for reaction, the ratio of the molar amount of the precipitant in the precipitant aqueous solution to the sum of the molar amounts of manganese and iron elements in the manganese-iron mixed metal salt solution can be (2.2-1.0):1, for example, it can be 2.2:1, 2.1:1, 2.0:1, 1.9:1, 1.8:1, 1.7:1, 1.6:1, 1.5:1, 1.4:1, 1.3:1, 1.2:1, 1.1:1, 1.0:1, or a range consisting of any of the above values. Alternatively, the ratio of the molar amount of the precipitant in the precipitant aqueous solution to the sum of the molar amounts of manganese and iron elements in the manganese-iron mixed metal salt solution can be (2.0-1.2):1, (1.8-1.4):1. Using an excess of precipitant can promote better precipitation of ferromanganese.

[0088] In some embodiments, the iron source solid or iron source aqueous solution is uniformly mixed with the refined manganese sulfate aqueous solution to obtain a manganese-iron mixed metal salt solution having a mass fraction of 10% to 30%, for example, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, or any range thereof. Alternatively, the mass fraction of the manganese-iron mixed metal salt solution obtained may be 12%-26%, or 12%-20%.

[0089] Optionally, when a solid iron source is used, water may be added during the mixing process to adjust the mass fraction of the manganese-iron mixed metal salt solution.

[0090] By using a lower concentration of manganese iron mixed metal salt solution, the impurity ion content in the reaction system is lower, for example, the content of calcium ions and magnesium ions is lower. During the precipitation reaction, the probability of impurity ions, such as calcium ions and magnesium ions, entering the manganese iron oxalate crystals is reduced, thereby further reducing the calcium and magnesium impurity content of the prepared manganese iron oxalate solid.

[0091] In some embodiments, the feeding rate of the ferromanganese mixed metal salt solution can be 10 mL / min-100 mL / min, for example, 10 mL / min, 20 mL / min, 30 mL / min, 40 mL / min, 50 mL / min, 60 mL / min, 70 mL / min, 80 mL / min, 90 mL / min, 100 mL / min, or a range consisting of any of the above values. Alternatively, the feeding rate of the ferromanganese mixed metal salt solution can be 20 mL / min-80 mL / min, 20 mL / min-70 mL / min, 20 mL / min-60 mL / min, or 20 mL / min-50 mL / min.

[0092] The use of a slower feed rate is conducive to the growth of ferromanganese oxalate grains, so that the obtained ferromanganese oxalate solid particles are larger, thereby improving the filtration and washing effect of impurities adsorbed on the surface of ferromanganese oxalate crystals.

[0093] The alkaline pH regulator can promote the dissociation of the precipitant into oxalate ions, thereby promoting the precipitation of ferromanganese. In some embodiments, the alkaline pH regulator can include a mixture of one or more of aqueous ammonia, aqueous sodium hydroxide, aqueous potassium hydroxide, aqueous barium hydroxide, and aqueous lithium hydroxide.

[0094] In some embodiments, the mass fraction of the alkaline pH adjuster may be 10%-25%.

[0095] In some embodiments, the pH value of the alkaline pH adjuster can be 11-13.

[0096] In some embodiments, the feed rate of the alkaline pH regulator can be 10 mL / min-100 mL / min, for example, 10 mL / min, 20 mL / min, 25 mL / min, 30 mL / min, 40 mL / min, 50 mL / min, 60 mL / min, 70 mL / min, 80 mL / min, 90 mL / min, 100 mL / min, or a range thereof. Alternatively, the feed rate of the alkaline pH regulator can be 20 mL / min-70 mL / min, 20 mL / min-50 mL / min, or 20 mL / min-40 mL / min.

[0097] In some embodiments, after the feeding of the ferromanganese mixed metal salt solution is completed, an alkaline pH regulator is added to continue the reaction to obtain a ferromanganese oxalate suspension. The reaction temperature can be 20°C-90°C, for example, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, or a range consisting of any of the above values. Alternatively, the reaction temperature can be 40°C-90°C, 60°C-90°C. The reaction under heating conditions can promote the dissociation of the precipitant to produce more oxalate ions, thereby promoting the precipitation of ferromanganese.

[0098] In some embodiments, after the feeding of the manganese-iron mixed metal salt solution is completed, an alkaline pH regulator is added to continue the reaction. In the step of obtaining a manganese-iron oxalate suspension, an alkaline pH regulator is added to continue the reaction until the pH value of the reaction system reaches 2-4, the feeding is stopped, and the reaction is stirred for 20 min-60 min.

[0099] In some embodiments, in the step of filtering, washing, and drying the obtained ferromanganese oxalate suspension to obtain ferromanganese oxalate solid, the filtration may be vacuum filtration.

[0100] In some embodiments, the obtained ferromanganese oxalate suspension is filtered, washed, and dried to obtain ferromanganese oxalate solid. The drying process can be known in the art. Optionally, the drying temperature can be 50°C-150°C, and the drying time can be 1h-4h.

[0101] In the above preparation method, unless otherwise specified, all raw materials can be purchased directly.

[0102] The present application also provides an embodiment of manganese ferrooxalate prepared by the above preparation method.

[0103] The present invention also provides a method for preparing lithium manganese iron phosphate.

[0104] The preparation method comprises the steps of: using a mixture of manganese iron oxalate prepared by the above preparation method and a lithium source, a phosphorus source and a carbon source as raw materials, and obtaining lithium manganese iron phosphate through sintering treatment.

[0105] In some embodiments, one or more of a source of doping element M, a source of doping element N, a source of doping element Q, and a source of doping element R are also added to the mixed material, where M represents a doping element at the manganese position and the iron position, N represents a doping element at the lithium position, Q represents a doping element at the phosphorus position, and R represents a doping element at the oxygen position.

[0106] The lithium source may be a lithium-containing compound known in the art that can be used to prepare lithium iron manganese phosphate. For example, the lithium source may include one or more of Li2CO3, LiOH, Li3PO4, and LiH2PO4.

[0107] The phosphorus source may be a phosphorus-containing compound known in the art that can be used to prepare lithium manganese iron phosphate. For example, the phosphorus source includes one or more of lithium phosphate, lithium dihydrogen phosphate, dilithium hydrogen phosphate, manganese hydrogen phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, and manganese iron hydrogen phosphate.

[0108] The carbon source may include one or more of an organic carbon source and an inorganic carbon source, and may optionally include one or more of glucose, sucrose, starch, fructose, polyvinyl alcohol, polyethylene glycol, and citric acid.

[0109] M represents a doping element for manganese and iron, and may be selected from one or more of Co, Mg, Zn, Ca, Ti, V, Ni, and Cr. The source of the doping element M may include one or more of hydrochloride, nitrate, sulfate, and acetate of the doping element M.

[0110] N represents a doping element for lithium sites, which may be one or more of Zn, Al, Na, K, Mg, Nb, Mo, and W. The source of the doping element N may include one or more of hydrochloride, nitrate, sulfate, and acetate of the doping element N.

[0111] Q represents a doping element for the phosphorus site, and may be selected from one or more of B, S, Si, and N. The source of the doping element Q may include one or more of sulfates, borates, nitrates, and silicates of the doping element Q.

[0112] R represents an oxygen-site doping element, which may be one or more of S, F, Cl, and Br. The source of the doping element R may include one or more of a simple substance of the doping element R and an ammonium salt.

[0113] In the above preparation method, unless otherwise specified, all raw materials can be purchased directly.

[0114] The present application also provides a lithium manganese iron phosphate prepared by the above-mentioned preparation method.

[0115] Lithium manganese iron phosphate may have 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, M represents the doping element for manganese and iron positions, which may be selected from one or more of Co, Mg, Zn, Ca, Ti, V, Ni, and Cr; N represents the doping element for lithium position, which may be selected from one or more of Zn, Al, Na, K, Mg, Nb, Mo, and W; Q represents the doping element for phosphorus position, which may be selected from one or more of B, S, Si, and N; R represents the doping element for oxygen position, which may be selected from 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-xy≤0.1, 0≤m≤0.1, 0≤n≤0.1, and lithium manganese iron phosphate is electrically neutral.

[0116] The surface of lithium manganese iron phosphate is also coated with carbon, which can improve the electronic conductivity of lithium manganese iron phosphate.

[0117] The lithium manganese iron phosphate provided in the embodiment of the present application can be used in a battery cell. The battery cell includes an electrode assembly and an electrolyte, and the electrode assembly includes a positive electrode sheet and a negative electrode sheet.

[0118] [Positive electrode]

[0119] In some embodiments, the positive electrode plate includes a positive electrode current collector and a positive electrode film layer located on at least one surface of the positive electrode current collector, and the positive electrode film layer includes the lithium manganese iron phosphate provided in the embodiments of the present application.

[0120] In some embodiments, the positive electrode film layer may further include other positive electrode active materials. For example, other positive electrode active materials may include, but are not limited to, one or more of lithium transition metal oxides and modified compounds thereof. As an example, lithium transition metal oxides may include, but are not limited to, one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their respective modified compounds. The modified compounds of the above-mentioned positive electrode active materials may be doping modification and / or surface coating modification of the positive electrode active materials.

[0121] In some embodiments, the positive electrode film layer may further optionally include a positive electrode conductive agent. As an example, the positive electrode conductive agent may include, but is not limited to, one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0122] In some embodiments, the positive electrode film layer may further optionally include a positive electrode binder. As an example, the positive electrode binder may include, but is not limited to, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylic resin, styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-based acrylic resin (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and one or more of carboxymethyl chitosan (CMCS).

[0123] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. As an example of a metal foil, aluminum foil may be used. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material may include, but is not limited to, one or more of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer may include, but is not limited to, one or more of polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0124] The positive electrode film is typically formed by coating a positive electrode slurry onto a positive electrode current collector, drying it, and cold pressing it. The positive electrode slurry is typically formed by dispersing the positive electrode active material, positive electrode conductive agent, positive electrode binder, and any other components in a solvent and stirring them uniformly. The solvent can be, but is not limited to, N-methylpyrrolidone (NMP).

[0125] [Negative electrode]

[0126] In some embodiments, the negative electrode sheet may include a negative electrode current collector and a negative electrode film layer located on at least one surface of the negative electrode current collector.

[0127] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base material. The composite current collector may be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0128] In some embodiments, the negative electrode active material may be a material known in the art. As an example, the negative electrode active material may include one or more of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. Silicon-based materials may include one or more of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may include one or more of elemental tin, tin oxides, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0129] In some embodiments, the negative electrode film layer may further optionally include a negative electrode binder. As examples, the binder may include one or more of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0130] In some embodiments, the negative electrode film layer may further include a negative electrode conductive agent. For example, the conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0131] In some embodiments, the negative electrode film layer may optionally further include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC)).

[0132] The negative electrode film is typically formed by coating a negative electrode slurry onto a negative electrode current collector, drying it, and cold pressing it. The negative electrode slurry is typically formed by dispersing the negative electrode active material, negative electrode conductive agent, negative electrode binder, and any other components in a solvent and stirring them uniformly. The solvent can be, but is not limited to, deionized water.

[0133] The negative electrode plate does not exclude other additional functional layers in addition to the negative electrode film layer. For example, in some embodiments, the negative electrode plate may further include a conductive primer layer (e.g., composed of a conductive agent and a binder) sandwiched between the negative electrode current collector and the negative electrode film layer and disposed on the surface of the negative electrode current collector; in some embodiments, the negative electrode plate may further include a protective layer covering the surface of the negative electrode film layer.

[0134] [Electrolytes]

[0135] Battery cells also include an electrolyte. The electrolyte conducts ions between the positive and negative electrodes. This application does not specifically limit the type of electrolyte; it can be selected based on needs. For example, the electrolyte can include one or more of a solid electrolyte, a gel electrolyte, and a liquid electrolyte (i.e., an electrolyte solution).

[0136] In some embodiments, the electrolyte is an electrolyte solution including an electrolyte salt and a solvent.

[0137] In some embodiments, as examples, the electrolyte salt may include, but is not limited to, one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bisfluorosulfonyl imide (LiFSI), lithium bistrifluoromethanesulfonyl imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalatoborate (LiDFOB), lithium dioxalatoborate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorobisoxalatophosphate (LiDFOP), and lithium tetrafluorooxalatophosphate (LiTFOP).

[0138] In some embodiments, the solvent may include, but is not limited to, one or more of an ester solvent, a sulfone solvent, and an ether solvent. As an example, the solvent may include, but is not limited to, ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS), and one or more of diethyl sulfone (ESE).

[0139] In some embodiments, the electrolyte may optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, or additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high-temperature performance, and additives that improve battery low-temperature power performance.

[0140] [Isolation film]

[0141] Battery cells using electrolytes, as well as some battery cells using solid electrolytes, also include a separator. The separator is placed between the positive and negative electrode sheets to prevent internal short circuits.

[0142] The present application has no particular limitation on the type of isolation membrane, and any known isolation membrane with a porous structure having good chemical stability and mechanical stability can be selected.

[0143] In some embodiments, the material of the isolation membrane may include, but is not limited to, one or more of fiberglass, non-woven fabric, polyethylene (PE), polypropylene (PP), and polyvinylidene fluoride. The isolation membrane may be a single-layer film or a multi-layer composite film. When the isolation membrane is a multi-layer composite film, the materials of each layer may be the same or different.

[0144] The preparation method of battery cells is well known. In some embodiments, the positive electrode sheet, separator, negative electrode sheet and electrolyte can be assembled to form a battery cell. As an example, the positive electrode sheet, separator, and negative electrode sheet can be formed into an electrode assembly through a winding process and / or a lamination process, and the electrode assembly is placed in an outer package, dried and injected with the above-mentioned electrolyte, and then subjected to packaging, standing, formation and other processes to obtain a battery cell. Multiple battery cells can also be further connected in series, in parallel or in a mixed connection to form a battery module. Multiple battery modules can also be connected in series, in parallel or in a mixed connection to form a battery pack. In some embodiments, multiple battery cells can also directly form a battery pack.

[0145] The embodiments of the present application also provide an electrical device, which includes a battery provided in the embodiments of the present application, and the battery is used to provide electrical energy. The battery can be used as a power source for the electrical device, and can also be used as an energy storage unit for the electrical device. The electrical device can be, but is not limited to, a mobile device (such as a mobile phone, a tablet computer, a laptop computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship and a satellite, an energy storage system, etc.

[0146] The electrical device can select a specific type of battery, such as a battery cell, a battery module, or a battery pack, according to its usage requirements.

[0147] Figure 6 The diagram is a schematic diagram of an exemplary electric device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of this device, a battery pack or battery module can be used.

[0148] As another example, an electric device may be a mobile phone, a tablet computer, a laptop computer, etc. Such an electric device is usually required to be lightweight and thin, and may use a battery cell as a power source.

[0149] Example

[0150] The following examples describe the present disclosure in more detail. These examples are intended to be illustrative only, as various modifications and variations within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are by mass, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further processing. The instruments used in the examples are commercially available.

[0151] Comparative Example 1

[0152] Take 1000g of industrial manganese sulfate solid, add 3000g of pure water, stir and dissolve, and vacuum filter to obtain an industrial manganese sulfate aqueous solution with a pH of 2.0. Take an appropriate amount of industrial manganese sulfate aqueous solution and measure the manganese content by titration to 10.39%.

[0153] 1769.1 g of industrial manganese sulfate aqueous solution was weighed, 625.8 g of ferrous sulfate heptahydrate solid was added, and then 2500 g of pure water was added. The mixture was stirred at room temperature (about 25° C.) until the ferrous sulfate heptahydrate solid was completely dissolved to obtain a manganese-iron mixed metal salt solution.

[0154] Weigh 754.49g of oxalic acid into a reaction vessel, add 5000g of pure water, start stirring, rotate at 600rpm, heat to 60°C, and keep warm. Use a peristaltic pump to add the manganese-iron mixed metal salt solution to the oxalic acid aqueous solution, and set the feed rate to 60mL / min. After the manganese-iron mixed metal salt solution is fed, add ammonia water to the reactor with a peristaltic pump, set the ammonia water feed rate to 50mL / min, wait until the pH value of the reaction system rises to 3.0, stop adding ammonia water, and continue stirring the reaction for 30min. Discharge the manganese-iron oxalate suspension, let it cool, vacuum filter, wash, and dry at 105°C to obtain a manganese-iron oxalate solid.

[0155] Example 1

[0156] 1000g of industrial manganese sulfate solid was added to 3000g of pure water, stirred and dissolved, and vacuum filtered to obtain an industrial manganese sulfate aqueous solution with a pH of 2.0. The industrial manganese sulfate aqueous solution was poured into a reaction vessel, heated to 50°C and maintained at 400rpm. 8g of manganese powder (99% or greater in purity) was then added to the industrial manganese sulfate aqueous solution. Stirring was continued while monitoring the pH of the solution. When the pH reached 4, the suspension was removed and vacuum filtered to obtain a refined manganese sulfate aqueous solution. An appropriate amount of the refined manganese sulfate aqueous solution was titrated to determine a manganese content of 10.45%.

[0157] 1758.9 g of refined manganese sulfate aqueous solution was weighed, 625.8 g of ferrous sulfate heptahydrate solid was added, and then 2500 g of pure water was added. The mixture was stirred at room temperature (about 25° C.) until the ferrous sulfate heptahydrate solid was completely dissolved to obtain a manganese-iron mixed metal salt solution.

[0158] Weigh 754.49g of oxalic acid into a reaction vessel, add 5000g of pure water, start stirring, the speed is 600rpm, heated to 60°C, and keep warm. Use a peristaltic pump to add the manganese iron mixed metal salt solution to the oxalic acid aqueous solution, and set the feed rate to 60mL / min. After the manganese iron mixed metal salt solution is fed, use a peristaltic pump to add ammonia water with a mass water separation of 15% to the reactor, set the ammonia water feed rate to 50mL / min, wait for the reaction system pH value to rise to 3.0, stop the ammonia water addition, and continue stirring the reaction for 30min. Discharge the oxalic acid ferromanganese suspension, let it stand and cool, vacuum filter, wash, and dry at 105°C to obtain oxalic acid ferromanganese solid.

[0159] Example 2

[0160] 1000g of industrial manganese sulfate solid was added to 3000g of pure water, stirred and dissolved, and vacuum filtered to obtain an industrial manganese sulfate aqueous solution with a pH of 2.0. The industrial manganese sulfate aqueous solution was poured into a reaction vessel, heated to 50°C and kept warm at 400rpm. 10g of manganese powder with a purity of 99% or greater was then added to the industrial manganese sulfate aqueous solution. Stirring was continued while monitoring the pH of the solution. When the pH reached 6, the suspension was removed and vacuum filtered to obtain a refined manganese sulfate aqueous solution. An appropriate amount of the refined manganese sulfate aqueous solution was taken and the manganese content was determined to be 10.71% by titration.

[0161] 1714.8 g of refined manganese sulfate aqueous solution was weighed, 625.8 g of ferrous sulfate heptahydrate solid was added, and then 2500 g of pure water was added. The mixture was stirred at room temperature (about 25° C.) until the ferrous sulfate heptahydrate solid was completely dissolved to obtain a manganese-iron mixed metal salt solution.

[0162] Weigh 754.49g of oxalic acid into a reaction vessel, add 5000g of pure water, start stirring, the speed is 600rpm, heated to 60°C, and keep warm. Use a peristaltic pump to add the manganese iron mixed metal salt solution to the oxalic acid aqueous solution, and set the feed rate to 60mL / min. After the manganese iron mixed metal salt solution is fed, use a peristaltic pump to add ammonia water with a mass water separation of 15% to the reactor, set the ammonia water feed rate to 50mL / min, wait for the reaction system pH value to rise to 3.0, stop the ammonia water addition, and continue stirring the reaction for 30min. Discharge the oxalic acid ferromanganese suspension, let it stand and cool, vacuum filter, wash, and dry at 105°C to obtain oxalic acid ferromanganese solid.

[0163] Example 3

[0164] 1000g of industrial manganese sulfate solid was added to 3000g of pure water, stirred and dissolved, and vacuum filtered to obtain an industrial manganese sulfate aqueous solution with a pH of 2.0. The industrial manganese sulfate aqueous solution was poured into a reaction vessel, heated to 50°C and kept warm at a stirring speed of 400rpm. 20g of manganese powder with a purity of 99% or greater was then added to the industrial manganese sulfate aqueous solution. Stirring was continued while observing the pH of the solution. When the pH reached 7.0, the suspension was removed and vacuum filtered to obtain a refined manganese sulfate aqueous solution. An appropriate amount of the refined manganese sulfate aqueous solution was taken, and the manganese content was determined to be 10.64% by titration.

[0165] 1727.5 g of refined manganese sulfate aqueous solution was weighed, 625.8 g of ferrous sulfate heptahydrate solid was added, and then 2500 g of pure water was added. The mixture was stirred at room temperature (about 25° C.) until the ferrous sulfate heptahydrate solid was completely dissolved to obtain a manganese-iron mixed metal salt solution.

[0166] Weigh 754.49g of oxalic acid into a reaction vessel, add 5000g of pure water, start stirring, the speed is 600rpm, heated to 60°C, and keep warm. Use a peristaltic pump to add the manganese iron mixed metal salt solution to the oxalic acid aqueous solution, and set the feed rate to 60mL / min. After the manganese iron mixed metal salt solution is fed, use a peristaltic pump to add ammonia water with a mass water separation of 15% to the reactor, set the ammonia water feed rate to 50mL / min, wait for the reaction system pH value to rise to 3.0, stop the ammonia water addition, and continue stirring the reaction for 30min. Discharge the oxalic acid ferromanganese suspension, let it stand and cool, vacuum filter, wash, and dry at 105°C to obtain oxalic acid ferromanganese solid.

[0167] Example 4

[0168] 1000g of industrial manganese sulfate solid was added to 3000g of pure water with stirring to dissolve, and then vacuum filtered to obtain an industrial manganese sulfate aqueous solution with a pH of 2.0. The industrial manganese sulfate aqueous solution was poured into a reaction vessel, heated to 50°C and insulated with stirring at 400rpm. 30g of manganese powder with a purity of 99% or greater was then added to the industrial manganese sulfate aqueous solution. Stirring was continued while monitoring the pH of the solution. When the pH reached 7.5, the suspension was removed and vacuum filtered to obtain a refined manganese sulfate aqueous solution. An appropriate amount of the refined manganese sulfate aqueous solution was taken, and the manganese content, as measured by titration, was 10.54%.

[0169] 1714.8 g of refined manganese sulfate aqueous solution was weighed, 625.8 g of ferrous sulfate heptahydrate solid was added, and then 2500 g of pure water was added. The mixture was stirred at room temperature (about 25° C.) until the ferrous sulfate heptahydrate solid was completely dissolved to obtain a manganese-iron mixed metal salt solution.

[0170] Weigh 754.49g of oxalic acid into a reaction vessel, add 5000g of pure water, start stirring, the speed is 600rpm, heated to 60°C, and keep warm. Use a peristaltic pump to add the manganese iron mixed metal salt solution to the oxalic acid aqueous solution, and set the feed rate to 60mL / min. After the manganese iron mixed metal salt solution is fed, use a peristaltic pump to add ammonia water with a mass water separation of 15% to the reactor, set the ammonia water feed rate to 50mL / min, wait for the reaction system pH value to rise to 3.0, stop the ammonia water addition, and continue stirring the reaction for 30min. Discharge the oxalic acid ferromanganese suspension, let it stand and cool, vacuum filter, wash, and dry at 105°C to obtain oxalic acid ferromanganese solid.

[0171] Example 5

[0172] 1000g of industrial manganese sulfate solid was added to 3000g of pure water, stirred and dissolved, and vacuum filtered to obtain an industrial manganese sulfate aqueous solution with a pH of 2.0. The industrial manganese sulfate aqueous solution was poured into a reaction vessel, heated to 50°C and kept warm at a stirring speed of 400rpm. 40g of manganese powder with a purity of 99% or greater was then added to the industrial manganese sulfate aqueous solution. Stirring was continued while monitoring the pH of the solution. When the pH reached 7.5, the suspension was removed and vacuum filtered to obtain a refined manganese sulfate aqueous solution. An appropriate amount of the refined manganese sulfate aqueous solution was taken and the manganese content, measured by titration, was 10.61%.

[0173] 1714.8 g of refined manganese sulfate aqueous solution was weighed, 625.8 g of ferrous sulfate heptahydrate solid was added, and then 2500 g of pure water was added. The mixture was stirred at room temperature (about 25° C.) until the ferrous sulfate heptahydrate solid was completely dissolved to obtain a manganese-iron mixed metal salt solution.

[0174] Weigh 754.49g of oxalic acid into a reaction vessel, add 5000g of pure water, start stirring, the speed is 600rpm, heated to 60°C, and keep warm. Use a peristaltic pump to add the manganese iron mixed metal salt solution to the oxalic acid aqueous solution, and set the feed rate to 60mL / min. After the manganese iron mixed metal salt solution is fed, use a peristaltic pump to add ammonia water with a mass water separation of 15% to the reactor, set the ammonia water feed rate to 50mL / min, wait for the reaction system pH value to rise to 3.0, stop the ammonia water addition, and continue stirring the reaction for 30min. Discharge the oxalic acid ferromanganese suspension, let it stand and cool, vacuum filter, wash, and dry at 105°C to obtain oxalic acid ferromanganese solid.

[0175] Example 6

[0176] 1000g of industrial manganese sulfate solid was added to 3000g of pure water, stirred and dissolved, and vacuum filtered to obtain an industrial manganese sulfate aqueous solution with a pH of 2.0. The industrial manganese sulfate aqueous solution was poured into a reaction vessel, heated to 50°C and kept warm at a stirring speed of 400rpm. 50g of manganese powder with a purity of 99% or greater was then added to the industrial manganese sulfate aqueous solution. Stirring was continued while monitoring the solution pH. When the solution pH reached 7.5, the suspension was removed and vacuum filtered to obtain a refined manganese sulfate aqueous solution. An appropriate amount of the refined manganese sulfate aqueous solution was taken, and the manganese content was determined to be 10.68% by titration.

[0177] 1714.8 g of refined manganese sulfate aqueous solution was weighed, 625.8 g of ferrous sulfate heptahydrate solid was added, and then 2500 g of pure water was added. The mixture was stirred at room temperature (about 25° C.) until the ferrous sulfate heptahydrate solid was completely dissolved to obtain a manganese-iron mixed metal salt solution.

[0178] Weigh 754.49g of oxalic acid into a reaction vessel, add 5000g of pure water, start stirring, the speed is 600rpm, heated to 60°C, and keep warm. Use a peristaltic pump to add the manganese iron mixed metal salt solution to the oxalic acid aqueous solution, and set the feed rate to 60mL / min. After the manganese iron mixed metal salt solution is fed, use a peristaltic pump to add ammonia water with a mass water separation of 15% to the reactor, set the ammonia water feed rate to 50mL / min, wait for the reaction system pH value to rise to 3.0, stop the ammonia water addition, and continue stirring the reaction for 30min. Discharge the oxalic acid ferromanganese suspension, let it stand and cool, vacuum filter, wash, and dry at 105°C to obtain oxalic acid ferromanganese solid.

[0179] Example 7

[0180] 1000g of industrial manganese sulfate solid was added to 3000g of pure water, stirred and dissolved, and vacuum filtered to obtain an industrial manganese sulfate aqueous solution with a pH of 2.0. The industrial manganese sulfate aqueous solution was poured into a reaction vessel, heated to 50°C and kept warm at a stirring speed of 400rpm. 40g of manganese powder with a purity of 99% or greater was then added to the industrial manganese sulfate aqueous solution. Stirring was continued while monitoring the pH of the solution. When the pH reached 7.5, the suspension was removed and vacuum filtered to obtain a refined manganese sulfate aqueous solution. An appropriate amount of the refined manganese sulfate aqueous solution was taken and the manganese content, measured by titration, was 10.68%.

[0181] 1720.3 g of refined manganese sulfate aqueous solution was weighed, 625.8 g of ferrous sulfate heptahydrate solid was added, and then 2500 g of pure water was added. The mixture was stirred at room temperature (about 25° C.) until the ferrous sulfate heptahydrate solid was completely dissolved to obtain a manganese-iron mixed metal salt solution.

[0182] Weigh 754.49g of oxalic acid into a reaction vessel, add 5000g of pure water, start stirring, rotate at 600rpm, heat to 60°C, and keep warm. Add the manganese iron mixed metal salt solution to the oxalic acid aqueous solution with a peristaltic pump, and set the feed rate to 30mL / min. After the manganese iron mixed metal salt solution is fed, add ammonia water with a mass water separation of 15% to the reactor with a peristaltic pump, set the ammonia water feed rate to 25mL / min, wait for the reaction system pH value to rise to 3.0, stop the ammonia water addition, and continue stirring the reaction for 30min. Discharge the oxalic acid ferromanganese suspension, let it stand and cool, vacuum filter, wash, and dry at 105°C to obtain oxalic acid ferromanganese solid.

[0183] Example 8

[0184] 1000g of industrial manganese sulfate solid was added to 3000g of pure water, stirred and dissolved, and vacuum filtered to obtain an industrial manganese sulfate aqueous solution with a pH of 2.0. The industrial manganese sulfate aqueous solution was poured into a reaction vessel, heated to 50°C and kept warm at a stirring speed of 400rpm. 40g of manganese powder with a purity of 99% or greater was then added to the industrial manganese sulfate aqueous solution. Stirring was continued while monitoring the pH of the solution. When the pH reached 7.5, the suspension was removed and vacuum filtered to obtain a refined manganese sulfate aqueous solution. An appropriate amount of the refined manganese sulfate aqueous solution was taken and the manganese content, measured by titration, was 10.68%.

[0185] 1720.3 g of refined manganese sulfate aqueous solution was weighed, 625.8 g of ferrous sulfate heptahydrate solid was added, and then 5000 g of pure water was added. The mixture was stirred at room temperature (about 25° C.) until the ferrous sulfate heptahydrate solid was completely dissolved to obtain a manganese-iron mixed metal salt solution.

[0186] Weigh 754.49g of oxalic acid into a reaction vessel, add 10000g of pure water, start stirring, the speed is 600rpm, heated to 60°C, and keep warm. Use a peristaltic pump to add the manganese iron mixed metal salt solution to the oxalic acid aqueous solution, and set the feed rate to 30mL / min. After the manganese iron mixed metal salt solution is fed, use a peristaltic pump to add ammonia water with a mass water separation of 15% to the reactor, set the ammonia water feed rate to 25mL / min, wait for the reaction system pH value to rise to 3.0, stop the ammonia water addition, and continue stirring the reaction for 30min. Discharge the oxalic acid ferromanganese suspension, let it stand and cool, vacuum filter, wash, and dry at 105°C to obtain oxalic acid ferromanganese solid.

[0187] Performance Testing

[0188] (1) Determination of manganese content in manganese sulfate aqueous solution

[0189] Prepare a standard solution of ammonium ferrous sulfate with a concentration of approximately 0.06 mol / L, and calibrate it with a potassium permanganate solution of known concentration to obtain the concentration c2 of the standard solution of ammonium ferrous sulfate.

[0190] Weigh 0.2 g (accurate to 0.0001 g) of manganese sulfate aqueous solution into a 250 mL conical flask, add 20 mL of concentrated phosphoric acid, then place on a hot plate and heat to about 150° C. Add 5 mL of concentrated nitric acid and shake well, and continue heating to boiling; after the brown gas in the conical flask is completely discharged and the liquid level returns to calm, add 2 mL of perchloric acid and shake well, and continue heating to boiling; after the liquid level returns to calm again, let it cool to room temperature for use.

[0191] Add 50 mL of pure water to a conical flask to fully dissolve the cooled solution. Use a 50 mL burette to titrate with ferrous ammonium sulfate standard solution. When the purple color of the solution almost fades, add 5 to 6 drops of N-phenylanthranilic acid indicator and shake well. Continue titrating until the solution turns bright yellow. Record the volume V3 of ferrous ammonium sulfate standard solution consumed in the titration.

[0192] Manganese content of manganese sulfate aqueous solution

[0193] m1 is the mass of the manganese sulfate aqueous solution weighed, in g. c2 is the concentration of the ammonium ferrous sulfate standard solution, in mol / L. V3 is the volume of the ammonium ferrous sulfate standard solution consumed in the titration, in mL.

[0194] (2) Determination of impurity content of ferromanganese oxalate solid

[0195] Weigh 0.2g of the prepared ferromanganese oxalate solid sample into a 100mL beaker, add 10mL of 10% nitric acid solution, heat and digest at 120°C for 0.5h, and dilute to volume with a 100mL volumetric flask; then use a pipette to transfer 1mL to a 100mL volumetric flask to obtain a test solution. The contents of calcium, magnesium, aluminum, copper, and zinc elements were determined using an inductively coupled plasma optical emission spectrometer. The test instrument was an Agilent 5800ICP-OES inductively coupled plasma optical emission spectrometer. The test results are shown in Table 1.

[0196] Table 1

[0197] Serial number Calcium / PPM Magnesium / PPM Aluminum / PPM Copper / PPM Zinc / PPM Comparative Example 1 321.40 2154.34 248.18 160.89 1256.24 Example 1 231.50 1847.67 123.90 93.50 1042.40 Example 2 120.44 877.05 18.14 11.47 605.16 Example 3 110.28 620.44 10.40 8.04 248.70 Example 4 100.32 520.53 8.48 5.39 165.37 Example 5 100.58 520.68 8.09 5.07 100.49 Example 6 100.89 520.93 8.25 5.48 100.63 Example 7 57.36 327.88 9.08 3.94 80.07 Example 8 37.58 249.77 9.03 3.91 70.96

[0198] It can be seen from the test results of Comparative Example 1 and Examples 1 to 8 that the preparation method provided in the examples of the present application can directly prepare ferromanganese oxalate using industrial manganese sulfate as raw material, and the prepared ferromanganese oxalate product has a lower impurity content, which can meet the use requirements of battery-grade ferromanganese oxalate.

[0199] From the test results of Examples 1 to 6, it can be seen that by further adjusting the pH value of the manganese sulfate suspension, the impurity ions in the industrial manganese sulfate can be better precipitated, thereby further reducing the impurity content of the prepared ferromanganese oxalate solid.

[0200] From the test results of Examples 4 to 6, it can be seen that compared with Example 4, the pH of the reaction system in Examples 5 and 6 no longer changes. It can be seen that the manganese powder in Examples 5 and 6 is excessive, and the excess manganese powder can undergo a replacement reaction with the impurity zinc ions in the solution, thereby further reducing the content of impurity zinc in the prepared ferromanganese oxalate product.

[0201] The test results of Examples 5 and 7 show that reducing the feed rate of the ferromanganese mixed metal salt solution can further reduce the impurity content of the prepared ferromanganese oxalate product. Using a slower feed rate is conducive to the growth of ferromanganese oxalate grains, resulting in larger ferromanganese oxalate solid particles, thereby improving the filtration effect of impurities adsorbed on the surface of the ferromanganese oxalate crystals, and further reducing the impurity content of the prepared ferromanganese oxalate product.

[0202] The test results of Examples 7 and 8 show that the use of a lower concentration of a manganese iron mixed metal salt solution can further reduce the impurity content of the prepared manganese iron oxalate product, particularly the calcium and magnesium impurity content. The lower the concentration of the manganese iron mixed metal salt solution, the lower the content of impurity ions in the reaction system. During the precipitation reaction, the probability of impurity ions, such as calcium ions and magnesium ions, entering the manganese iron oxalate crystals is reduced, thereby further reducing the impurity content of the prepared manganese iron oxalate product.

[0203] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A method for preparing ferromanganese oxalate, characterized in that: The steps include: Provide industrial manganese sulfate aqueous solution; adding manganese powder to an industrial manganese sulfate aqueous solution, reacting under stirring and heating conditions to obtain a manganese sulfate suspension, wherein the pH of the obtained manganese sulfate suspension is controlled between 4 and 8, and then filtering to obtain a refined manganese sulfate aqueous solution; uniformly mixing an iron source solid or an iron source aqueous solution with a refined manganese sulfate aqueous solution to obtain a manganese-iron mixed metal salt solution; adding the obtained manganese-iron mixed metal salt solution into a precipitant aqueous solution for reaction, wherein the precipitant comprises one or more of oxalic acid and oxalate; After the feeding of the ferromanganese mixed metal salt solution is completed, an alkaline pH regulator is added to continue the reaction to obtain a ferromanganese oxalate suspension, which is then filtered, washed, and dried to obtain a ferromanganese oxalate solid.

2. The preparation method according to claim 1, characterized in that The pH of the obtained manganese sulfate suspension is controlled between 7 and 7.

8.

3. The preparation method according to any one of claims 1 to 2, characterized in that In the step of adding manganese powder to an industrial manganese sulfate aqueous solution and reacting under stirring and heating conditions to obtain a manganese sulfate suspension, The mass fraction of the industrial manganese sulfate aqueous solution is 10%-40%; and / or, The mass of the manganese powder is 0.1%-5% of the mass of the industrial manganese sulfate in the industrial manganese sulfate aqueous solution; and / or, The purity of the manganese powder is greater than or equal to 99%; and / or, The heating temperature is 40°C-80°C.

4. The preparation method according to any one of claims 1 to 3, characterized in that The iron source solid or the iron source aqueous solution is evenly mixed with the refined manganese sulfate aqueous solution, and the mass fraction of the obtained manganese and iron mixed metal salt solution is 10% to 30%.

5. The preparation method according to any one of claims 1 to 4, characterized in that In the step of adding the obtained manganese-iron mixed metal salt solution into the precipitant aqueous solution to react, The ratio of the molar amount of the precipitant in the precipitant aqueous solution to the sum of the molar amounts of the manganese element and the iron element in the manganese-iron mixed metal salt solution is (2.2-1.0):1; and / or, The reaction temperature is 20°C-90°C.

6. The preparation method according to any one of claims 1 to 5, characterized in that In the step of adding the obtained manganese-iron mixed metal salt solution into the precipitant aqueous solution to react, The mass fraction of the precipitant aqueous solution is 5.0%-30.0%; and / or, The feeding rate of the manganese-iron mixed metal salt solution is 10 mL / min-100 mL / min.

7. The preparation method according to claim 6, characterized in that The mass fraction of the precipitant aqueous solution is 6.0%-16.0%; and / or, The feeding rate of the manganese-iron mixed metal salt solution is 20 mL / min-70 mL / min.

8. The preparation method according to any one of claims 1 to 7, characterized in that After the manganese-iron mixed metal salt solution is fed, an alkaline pH regulator is added to continue the reaction to obtain a manganese-iron oxalate suspension. The alkaline pH regulator includes a mixture of one or more of ammonia water, sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, barium hydroxide aqueous solution, and lithium hydroxide aqueous solution; and / or, The mass fraction of the alkaline pH regulator is 10%-25%; and / or, The pH value of the alkaline pH regulator is 11-13.

9. The preparation method according to any one of claims 1 to 8, characterized in that After the manganese-iron mixed metal salt solution is fed, an alkaline pH regulator is added to continue the reaction to obtain a manganese-iron oxalate suspension. The feeding rate of the alkaline pH regulator is 10 mL / min-100 mL / min; and / or, The reaction temperature is 20°C-90°C; and / or, Add an alkaline pH regulator and continue the reaction until the pH value of the reaction system is 2-4, stop feeding, and continue stirring the reaction for 20 min-60 min.

10. The preparation method according to any one of claims 1 to 9, characterized in that: The method for providing an industrial manganese sulfate aqueous solution comprises the following steps: Dissolve industrial manganese sulfate in water, stir until completely dissolved, and filter to obtain an industrial manganese sulfate aqueous solution.

11. The preparation method according to any one of claims 1 to 10, characterized in that: In the step of uniformly mixing the iron source solid or the iron source aqueous solution with the refined manganese sulfate aqueous solution to obtain a manganese-iron mixed metal salt solution, The iron source includes one or more of ferrous sulfate, ferrous nitrate, ferrous chloride, and ferrous acetate; and / or, The molar ratio of manganese to iron in the manganese-iron mixed metal salt solution is 5:5-8:

2.

12. A ferromanganese oxalate, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 11.

13. A method for preparing lithium manganese iron phosphate, characterized in that: The method comprises the following steps: using a mixture of manganese iron oxalate prepared by the preparation method according to any one of claims 1 to 11 and a lithium source, a phosphorus source and a carbon source as a raw material, and obtaining lithium manganese iron phosphate through sintering treatment.

14. The preparation method according to claim 13, characterized in that One or more sources of doping elements M, N, Q, and R are also added to the mixed materials, where M represents the doping element at the manganese and iron positions, N represents the doping element at the lithium position, Q represents the doping element at the phosphorus position, and R represents the doping element at the oxygen position.

15. A lithium manganese iron phosphate, characterized in that: It is prepared by the preparation method according to any one of claims 13-14.

16. A positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer located on at least one surface of the positive electrode current collector, characterized in that: The positive electrode film layer comprises lithium manganese iron phosphate prepared by the preparation method according to any one of claims 13-14.

17. A battery, characterized in that: Including the positive electrode sheet according to claim 16.

18. An electrical device, characterized in that: The battery according to claim 17 is used to provide electrical energy.

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