Ferromanganese phosphate precursor, lithium iron manganese phosphate, preparation method of lithium iron manganese phosphate, battery monomer, battery device and power utilization device

Abstract

The invention relates to an iron manganese phosphate precursor, lithium iron manganese phosphate and a preparation method thereof, a battery monomer, a battery device and a power utilization device. The preparation method comprises the following steps: mixing a divalent manganese source, a divalent iron source and an acidic solution to obtain a first mixed solution; an aqueous solution containing an alkali source is mixed with a complexing agent, a second mixed solution is obtained, and the complexing agent comprises an aminocarboxylic acid compound; adding an alkaline solution containing a complexing agent into the first mixed solution and the second mixed solution in a parallel flow manner, and carrying out single-phase coprecipitation to obtain ferromanganese hydroxide; mixing ferromanganese hydroxide with an aqueous solution containing an antioxidant to obtain first slurry; mixing an aqueous solution containing a phosphorus source with the first slurry to react until the pH value of the system is 4.5-6, so as to obtain ferromanganese phosphate; and mixing the ferrous manganese phosphate with a lithium source, and sintering to obtain the lithium iron manganese phosphate. According to the preparation method, the molar ratio of manganese ions to iron ions to phosphate ions in the precursor can be accurately adjusted, the precursor with high purity is obtained, and then the lithium manganese iron phosphate with high purity is obtained.

Description

Technical Field

[0001] The present disclosure relates to the field of batteries, and particularly to an iron manganese phosphate precursor, lithium iron manganese phosphate, a preparation method thereof, a battery cell, a battery device, and an electrical device. Background Art

[0002] Currently, lithium-containing transition metal phosphates are important cathode active materials for lithium-ion battery cells. Due to advantages such as stable structure and high energy density, they are widely used in various lithium-ion battery cells, such as power batteries. However, the purity of lithium-containing transition metal phosphates still needs to be improved. Summary of the Invention

[0003] The present disclosure provides an iron manganese phosphate precursor, lithium iron manganese phosphate, a preparation method thereof, a battery cell, a battery device, and an electrical device, which can more precisely adjust the molar ratio of manganese ions, iron ions, and phosphate ions in the iron manganese phosphate precursor, prepare an iron manganese phosphate precursor with a higher purity, and further obtain a lithium iron manganese phosphate cathode active material with a higher purity.

[0004] In a first aspect, the present disclosure provides a preparation method of an iron manganese phosphate precursor, including: mixing a divalent manganese source, a divalent iron source, and an acidic solution to obtain a first mixed solution; mixing an aqueous solution containing an alkali source and a complexing agent to obtain a second mixed solution, where the complexing agent includes an aminocarboxylic acid compound; adding the first mixed solution and the second mixed solution into a basic solution containing a complexing agent in a co-current manner to perform a single-phase co-precipitation reaction to obtain a manganese iron hydroxide slurry; mixing the manganese iron hydroxide slurry with an aqueous solution containing an antioxidant to obtain a first slurry; mixing an aqueous solution containing a phosphorus source with the first slurry and reacting until the pH of the system is 4.5 - 6 to obtain an iron manganese phosphate precursor; mixing the iron manganese phosphate precursor with a lithium source and then performing a sintering treatment to obtain a lithium iron manganese phosphate cathode active material.

[0005] In some embodiments, the preparation method includes: mixing an aqueous solution containing a phosphorus source with the first slurry and reacting until the pH of the system is 5.2 - 5.4 to obtain an iron manganese phosphate precursor.

[0006] In some embodiments, the aminocarboxylic acid compound includes one or more of ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetate, tetrasodium ethylenediaminetetraacetate, diethylenetriaminepentaacetic acid, nitrilotriacetic acid, and ethylenediaminediacetic acid.

[0007] In some embodiments, the addition amount of the complexing agent in the second mixed solution is 1% - 3% of the total molar amount of ferrous ions and manganese ions.

[0008] In some embodiments, the concentration of the complexing agent in the basic solution containing the complexing agent is 0.01 - 0.05 mol / L.

[0009] In some embodiments, the pH value of the solution during the single-phase coprecipitation reaction is 9.6 - 10.4.

[0010] In some embodiments, the time of the single-phase coprecipitation reaction is 270 - 300 min.

[0011] In some embodiments, the temperature of the single-phase coprecipitation reaction is 55°C - 65°C.

[0012] In some embodiments, mixing the aqueous solution containing a phosphorus source with the first slurry includes: adding the aqueous solution containing a phosphorus source to the first slurry.

[0013] In some embodiments, the preparation method further includes: performing impurity removal treatment on the manganese iron hydroxide slurry.

[0014] In some embodiments, the manganese source includes one or more of manganese sulfate, manganese chloride, manganese nitrate, and manganese acetate.

[0015] In some embodiments, the iron source includes one or more of ferrous sulfate, ferrous chloride, ferrous nitrate, and ferrous acetate.

[0016] In some embodiments, the acid in the acidic solution includes one or more of sulfuric acid, hydrochloric acid, nitric acid, and ascorbic acid.

[0017] In some embodiments, the base source includes one or more of sodium hydroxide and potassium hydroxide.

[0018] In some embodiments, the antioxidant includes one or more of ascorbic acid and isoascorbic acid.

[0019] In some embodiments, the phosphorus source includes one or more of phosphoric acid, sodium dihydrogen phosphate, and potassium dihydrogen phosphate.

[0020] In a second aspect, the present disclosure provides a manganese iron phosphite precursor, and the chemical formula of the manganese iron phosphite precursor is (Mn x Fe (1-x) ) 3 (PO 4 ) y ·nH 2 O, 0 < x < 1.00, 2.00 ≤ y ≤ 2.01, 0 ≤ n ≤ 10; the manganese iron phosphite precursor includes primary particles and secondary particles formed by agglomeration of the primary particles; the primary particles include flaky particles, and the secondary particles include spherical particles.

[0021] In some embodiments, the volume particle size distribution Dv50 of the manganese iron phosphite precursor is 36 - 44 μm.

[0022] In some embodiments, the mass content of sodium element in the manganese iron phosphite precursor is less than or equal to 35 ppm.

[0023] In some embodiments, the mass content of sulfur element in iron manganese phosphate is less than or equal to 110 ppm.

[0024] In a third aspect, the present disclosure provides a lithium iron manganese phosphate, which is prepared from the iron manganese phosphate precursor of the second aspect of the present disclosure.

[0025] In a fourth aspect, the present disclosure provides a battery cell, including the lithium iron manganese phosphate of the third aspect of the present disclosure.

[0026] In a fifth aspect, the present disclosure provides a battery device, including a plurality of the battery cells of the fourth aspect of the present disclosure.

[0027] In a sixth aspect, the present disclosure provides an electrical device, including the battery cell of the fourth aspect of the present disclosure or the battery device of the fifth aspect of the present disclosure.

[0028] In the embodiments of the present disclosure, a divalent manganese source, a divalent iron source and an acidic solution are mixed to obtain a first mixed solution; an aqueous solution containing an alkali source and a complexing agent are mixed to obtain a second mixed solution, and the complexing agent includes an aminocarboxylic acid compound; the first mixed solution and the second mixed solution are added in a co-current manner to a basic solution containing a complexing agent for a single-phase co-precipitation reaction to obtain a manganese iron hydroxide slurry, thereby achieving an atomic-level uniform mixing of manganese ions and iron ions and precisely adjusting the molar ratio of metal ions. And by mixing an aqueous solution containing a phosphorus source with the first slurry and reacting until the pH of the system is 4.5 - 6, the hydrogen ions in the phosphorus source can be quickly and completely ionized, thereby reducing the generation of internal crystal impurities and surface impurity residues, preparing an iron manganese phosphate precursor with a higher purity, and further obtaining a lithium iron manganese phosphate cathode active material with a higher purity. Description of the Drawings

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required to be used in the embodiments of the present disclosure will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure, and those of ordinary skill in the art can also obtain other drawings according to the drawings without creative efforts.

[0030] Figure 1 Schematic diagram of a battery cell provided by some embodiments of the present disclosure.

[0031] Figure 2 Schematic diagram of an electrical device provided by some embodiments of the present disclosure.

[0032] Figure 3 Scanning electron microscope image of manganese iron hydroxide prepared in Example 1 of the present disclosure.

[0033] Figure 4Low-magnification scanning electron microscope image of the iron manganese phosphate precursor prepared in Example 1 of the present disclosure.

[0034] Figure 5 High-magnification scanning electron microscope image of the iron manganese phosphate precursor prepared in Example 1 of the present disclosure.

[0035] Figure 6 EDS element distribution maps of O, Fe, Mn, and P in the iron manganese phosphate precursor prepared in Example 1 of the present disclosure.

[0036] Figure 7 EDS element distribution map of Mn in the iron manganese phosphate precursor prepared in Example 1 of the present disclosure.

[0037] Figure 8 EDS element distribution map of Fe in the iron manganese phosphate precursor prepared in Example 1 of the present disclosure.

[0038] Figure 9 EDS element distribution map of P in the iron manganese phosphate precursor prepared in Example 1 of the present disclosure.

[0039] Figure 10 EDS element distribution map of O in the iron manganese phosphate precursor prepared in Example 1 of the present disclosure.

[0040] In the drawings, the drawings are not necessarily drawn to actual scale. Detailed Description of the Specific Embodiments

[0041] Hereinafter, embodiments of the iron manganese phosphate precursor, lithium iron manganese phosphate, and their preparation methods, battery cells, battery devices, and electrical devices of the present disclosure will be specifically disclosed with appropriate reference to the drawings. However, there may be cases where unnecessary details are omitted. For example, there may be cases where detailed descriptions of well-known matters and repeated descriptions of actually identical 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 disclosure and are not intended to limit the subject matter recited in the claims.

[0042] The "range" disclosed in the present disclosure is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular range. The ranges defined in this way can include the end values or not include the end values, and can be combined arbitrarily, 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 contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all contemplated: 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4, and 2 - 5. In the present disclosure, unless otherwise stated, the numerical range "a - b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" have been fully listed herein, and "0 - 5" is only an abbreviated representation of these numerical combinations. Additionally, when stating that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0043] If there is no special instruction, all embodiments and optional embodiments of the present disclosure can be combined with each other to form a new technical solution, and such a technical solution should be considered to be included in the content of the present disclosure.

[0044] If there is no special instruction, all technical features and optional technical features of the present disclosure can be combined with each other to form a new technical solution, and such a technical solution should be considered to be included in the content of the present disclosure.

[0045] If there is no special instruction, all steps of the present disclosure can be carried out sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method can include steps (a) and (b) carried out sequentially, or can also include steps (b) and (a) carried out sequentially. For example, when it is mentioned that the method may further include step (c), it means that step (c) can be added to the method in any order. For example, the method can include steps (a), (b), and (c), or can also include steps (a), (c), and (b), or can also include steps (c), (a), and (b), etc.

[0046] In the present disclosure, the terms "a plurality of" and "a variety of" mean two or more than two.

[0047] In the description of the embodiments of the present disclosure, if there is no special description, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the horizontal height of the first feature is less than that of the second feature.

[0048] Unless otherwise specified, the test temperature of each parameter mentioned in the present disclosure is 25 °C.

[0049] Currently, the methods for industrially mass-producing lithium iron manganese phosphate cathode active materials mainly include solid-phase methods (e.g., high-temperature solid-phase method and carbothermal reduction method) and liquid-phase methods (e.g., co-precipitation method). It is difficult to achieve uniform mixing of Mn / Fe elements at the atomic / molecular level by the solid-phase method. At the same time, the particles of the cathode active material prepared by the solid-phase method are prone to agglomeration and have a high control difficulty, which in turn leads to poor phase homogeneity of the cathode active material. In contrast, the co-precipitation method can enable the multi-phase co-precipitation of Mn / Fe elements and is currently the most promising method for industrially mass-producing precursors. The quality of the precursor directly affects the physical and chemical indexes and electrochemical performance of the cathode active material, and the quality of the precursors prepared by different methods varies greatly. Therefore, the preparation method of the precursor is particularly crucial.

[0050] How to achieve homogeneous co-precipitation of Mn and Fe elements, realize uniform mixing at the atomic / molecular level, and precisely adjust the molar ratio of manganese ions, iron ions and phosphate ions in the iron manganese phosphite precursor to obtain an iron manganese phosphite precursor with a relatively high purity is also a technical problem that needs to be solved urgently at present.

[0051] In view of this, the present disclosure provides an iron manganese phosphite precursor, lithium iron manganese phosphate, a preparation method thereof, a battery cell, a battery device and an electrical device, which can relatively precisely adjust the molar ratio of manganese ions, iron ions and phosphate ions in the iron manganese phosphite precursor, prepare an iron manganese phosphite precursor with a relatively high purity, and further obtain a lithium iron manganese phosphate cathode active material with a relatively high purity.

[0052] The present disclosure provides a method for preparing lithium iron manganese phosphate. The preparation method includes the following steps: mixing a divalent manganese source, a divalent iron source with an acidic solution to obtain a first mixed solution; mixing an aqueous solution containing an alkali source with a complexing agent to obtain a second mixed solution, wherein the complexing agent includes an aminocarboxylic acid compound; adding the first mixed solution and the second mixed solution in a parallel flow to an alkaline solution containing a complexing agent to carry out a single-phase coprecipitation reaction to obtain a manganese iron hydroxide slurry; mixing the manganese iron hydroxide slurry with an aqueous solution containing an antioxidant to obtain a first slurry; mixing an aqueous solution containing a phosphorus source with the first slurry and reacting until the pH of the system is 4.5 - 6 to obtain a lithium iron manganese phosphate precursor; mixing the lithium iron manganese phosphate precursor with a lithium source and then carrying out a sintering treatment to obtain a lithium iron manganese phosphate cathode active material.

[0053] The solubility product constants of manganese and iron hydroxides are small, and the precipitation rate is fast. At the same time, the solubility product constant of iron hydroxide is much smaller than that of manganese hydroxide. Therefore, it is difficult to achieve single-phase coprecipitation by directly reacting a metal salt solution containing manganese ions and iron ions with an alkaline solution containing ammonia water. At the same time, a large amount of crystal nucleus colloid precipitation is easily generated during the reaction, and it is difficult to effectively filter and remove impurities from the product. In addition, because Fe 2+ is difficult to react with ammonia water to form a stable complex, it is impossible to directly adopt the process of NCM ternary precursor to prepare manganese iron hydroxide.

[0054] In addition, ammonia water is easy to volatilize, its concentration varies greatly with time and temperature, and it is difficult to ensure that the concentration of ammonia water in the storage tank does not change during industrial production. Therefore, using ammonia water as a complexing agent will cause a large change in the concentration of the complexing agent in the reaction system during continuous production, resulting in uncontrollability of production.

[0055] In the embodiment of the present disclosure, an aminocarboxylic acid compound is used as a complexing agent. By adjusting the precipitation rate of metal ions in the reaction system, the co-complexation of Mn 2+ and Fe 2+ can be achieved, and then slowly released to carry out a single-phase coprecipitation reaction with OH - to realize the sedimentation of Mn 2+ and Fe 2+ at the same order of magnitude, and precisely adjust the molar ratio of manganese ions and iron ions in the lithium iron manganese phosphate precursor.

[0056] Moreover, the aminocarboxylic acid compound itself is a solid, and the purity of the aminocarboxylic acid compound changes little with time and temperature. Using the aminocarboxylic acid compound as a complexing agent can quantify the reaction materials and make the production process more stable and controllable.

[0057] In the embodiments of the present disclosure, a divalent manganese source, a divalent iron source and an acidic solution are mixed to obtain a first mixed solution; an aqueous solution containing an alkali source and a complexing agent are mixed to obtain a second mixed solution, and the complexing agent includes an aminocarboxylic acid compound; the first mixed solution and the second mixed solution are added in parallel flow to an alkaline solution containing a complexing agent to carry out a single-phase coprecipitation reaction to obtain a manganese iron hydroxide slurry, thereby realizing an atomic-level uniform mixing of manganese ions and iron ions and simultaneously adjusting the molar ratio of metal ions more precisely. And by mixing an aqueous solution containing a phosphorus source with the first slurry and reacting until the pH of the system is 4.5-6, the hydrogen ions in the phosphorus source can be quickly and completely ionized, thereby reducing the generation of internal crystal impurities and surface impurity residues, and preparing a relatively high-purity iron manganese phosphate precursor, and further obtaining a relatively high-purity lithium manganese iron phosphate cathode active material.

[0058] The "single-phase coprecipitation reaction" in the embodiments of the present disclosure means that divalent manganese ions and divalent iron ions precipitate at the same order of magnitude. Specifically, the first mixed solution and the second mixed solution are added in parallel flow to an alkaline solution containing a complexing agent. After the aminocarboxylic acid compound complexes divalent manganese ions and divalent iron ions at the same time, the alkali source is used as a precipitating agent to realize the precipitation of divalent manganese ions and divalent iron ions at the same order of magnitude. Furthermore, while facilitating the atomic / molecular-level mixing of manganese ions and iron ions, the molar ratio of metal ions can be adjusted more precisely.

[0059] In addition, the reaction process between the aqueous solution containing a phosphorus source and the first slurry is a solid-liquid reaction with a fast reaction rate and a high degree of uniformity, so it is easier to generate well-crystallized iron manganese phosphate.

[0060] In the embodiments of the present disclosure, the addition amount of the acidic solution in the first mixed solution is not limited as long as it can play a role in reducing the oxidation of manganese ions and iron ions. Unless otherwise specified, the manganese ions and iron ions mentioned in the embodiments of the present disclosure both refer to divalent manganese ions and divalent iron ions.

[0061] In some embodiments, the preparation method may include: mixing an aqueous solution containing a phosphorus source with the first slurry and reacting until the pH of the system is 5.2-5.4 to obtain an iron manganese phosphate precursor. Thereby further adjusting the molar ratio of manganese ions, iron ions and phosphate ions in the iron manganese phosphate precursor more precisely, preparing a relatively high-purity iron manganese phosphate precursor, and further obtaining a relatively high-purity lithium manganese iron phosphate cathode active material.

[0062] In some embodiments, the aminocarboxylic acid compound may include one or more of ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetate, tetrasodium ethylenediaminetetraacetate, diethylenetriaminepentaacetic acid, nitrilotriacetic acid and ethylenediaminediacetic acid.

[0063] In some embodiments, the addition amount of the complexing agent in the second mixed solution can be 1% - 3% of the total molar amount of ferrous ions and manganese ions. For example, it can be 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.6%, 2.8%, 3%, or a range composed of any two of the above values. Optionally, it can be 1.5% - 2.5%.

[0064] By adjusting the addition amount of the complexing agent in the second mixed solution within the above range, the separation difficulty between impurities and manganese iron hydroxide particles can be reduced, thereby reducing the impurity content in manganese iron hydroxide. In addition, when the addition amount of the complexing agent is within the above range, the residual amounts of manganese ions and iron ions in the reaction mother liquor can also be reduced, the utilization rates of manganese ions and iron ions can be improved, and the molar ratio of metal ions in the iron manganese phosphate precursor can be further precisely adjusted.

[0065] In some embodiments, the concentration of the complexing agent in the alkaline solution containing the complexing agent can be 0.01 - 0.05 mol / L.

[0066] In the embodiments of the present disclosure, by adjusting the concentration of the complexing agent in the alkaline solution containing the complexing agent within the above range, the concentration of the complexing agent during the reaction process can be kept consistent, thereby producing a good complexing effect.

[0067] In some embodiments, the pH value of the solution during the single-phase coprecipitation reaction process can be 9.6 - 10.4. For example, it can be 9.6, 9.7, 9.8, 9.9, 10, 10.1, 10.2, 10.3, 10.4, or a range composed of any two of the above values. Optionally, it can be 9.8 - 10.2.

[0068] According to the principles of crystallography, the particle size of the crystal grains is jointly determined by the nucleation rate and the growth rate. When the nucleation rate is greater than the growth rate, the particle size of the product is relatively small; when the nucleation rate is less than the growth rate, the crystal grains will grow continuously, resulting in a larger particle size of the product.

[0069] In the embodiments of the present disclosure, by adjusting the pH value of the solution during the single-phase coprecipitation reaction process within the above range, the nucleation rate and the growth rate of the manganese iron hydroxide particle crystal grains can be adjusted, and manganese iron hydroxide particles with a particle size within a suitable range can be obtained. At the same time, the generated manganese iron hydroxide slurry is also convenient for filtration, the impurity content inside the manganese iron hydroxide can be reduced (such as reducing the content of sodium ions and sulfate ions), the antioxidant property of the manganese iron hydroxide particles can be improved, the utilization rates of manganese ions and iron ions in the solution can be increased, and the molar ratio of manganese ions and iron ions in the iron manganese phosphate precursor can be further precisely adjusted.

[0070] In some embodiments, the fluctuation range of the solution pH during the single-phase coprecipitation reaction process can be ±1. Optionally, it can be ±0.05.

[0071] By adjusting the pH of the solution within the above range, the manganese ions and iron ions in the solution can be completely precipitated and stable compounds can be formed.

[0072] In some embodiments, the volume particle size distribution Dv50 of iron manganese hydroxide is 4.3 - 10.8 μm, and can be optionally 6 - 10.5 μm.

[0073] Dv50 represents the particle size corresponding to when the cumulative volume distribution percentage of the material reaches 50%. Referring to GB / T19077 - 2016, a laser particle size analyzer can be used for testing. During the test, take a clean small beaker, add 1 g of the sample to be tested, add 20 ml of deionized water, and ultrasonicate for 5 min at 53 KHz / 120 W to ensure that the sample is completely dispersed; turn on the laser particle size analyzer, clean the optical path system, and automatically test the background; stir the ultrasonified solution to be tested to make it evenly dispersed, place it in the sample cell as required, and start measuring the particle size. The test instrument can be a MasterSizer 3000 laser particle size analyzer.

[0074] The volume particle size distribution Dv50 of iron manganese hydroxide within the above range is beneficial to filtering out impurities such as sodium ions and sulfate ions, and at the same time, iron manganese hydroxide is not easily oxidized by air.

[0075] In some embodiments, the time for the single - phase co - precipitation reaction can be 270 - 300 min.

[0076] In the embodiments of the present disclosure, by adjusting the feeding rate of the first mixed solution, the reaction time of the single - phase co - precipitation can be adjusted. The feeding rate of the second mixed solution is used to adjust the pH of the solution during the single - phase co - precipitation reaction to be stable within the range of 9.6 - 10.4. When the feeding of the first mixed solution is completed, the feeding is stopped, and the reaction solution is subjected to aging treatment.

[0077] It can be understood that the time for the single - phase co - precipitation reaction includes the time for feeding the first mixed solution and the time for aging treatment after the feeding of the first mixed solution is completed.

[0078] By adjusting the time for the single - phase co - precipitation reaction within the above range, the precipitation rate of iron manganese hydroxide can be adjusted, and thus the particle size of iron manganese hydroxide particles can be further adjusted.

[0079] In some embodiments, an inert gas is introduced into the alkaline solution containing the complexing agent. This can reduce the oxygen content in the solution, thereby further reducing the oxidation of manganese ions and iron ions during the subsequent reaction process.

[0080] In some embodiments, the inert gas can be one or more of nitrogen, argon, and helium.

[0081] In some embodiments, the temperature of the single-phase coprecipitation reaction can be 55 - 65 °C.

[0082] By adjusting the temperature of the single-phase coprecipitation reaction within the above range, the collision of solute molecules can be promoted, the reaction process can be accelerated, and the process of self-assembly of primary particles of iron manganese hydroxide into secondary particles can be accelerated, thereby enabling rapid precipitation.

[0083] In some embodiments, mixing the aqueous solution containing a phosphorus source with the first slurry includes: adding the aqueous solution containing a phosphorus source to the first slurry.

[0084] In the embodiments of the present disclosure, the reaction between the aqueous solution containing a phosphorus source and the first slurry is a solid-liquid reaction, which is based on an acid-base neutralization reaction. By adding the aqueous solution containing a phosphorus source to the first slurry, that is, adopting a continuous reaction mode of adding acid to base, the hydrogen ions in the aqueous solution containing a phosphorus source can be rapidly and completely ionized, and the ionized phosphate ions can quickly combine with metal ions to form stable iron manganese phosphate precipitate, further improving the purity of iron manganese phosphate.

[0085] In the embodiments of the present disclosure, the addition amount of the aqueous solution containing a phosphorus source is adjusted according to the reaction cut-off pH.

[0086] In some embodiments, the fluctuation range of the reaction cut-off pH can be ±0.1, and can be optionally ±0.05.

[0087] The precipitate of the above reaction can be composed of one or two of (Mn 0.6 Fe 0.4 )(OH) 2 , (Mn 0.6 Fe 0.4 ) 3 (PO 4 ) 2 and (Mn 0.6 Fe 0.4 )HPO 4 . By carrying out the above reaction by adding acid to base, (Mn 0.6 Fe 0.4 )(OH) 2 gradually reacts to form (Mn 0.6 Fe 0.4 ) 3 (PO 4 ) 2 . If phosphoric acid is continuously added, the excess phosphoric acid will react with the newly formed (Mn 0.6 Fe 0.4 ) 3 (PO 4 ) 2 again to form (Mn 0.6 Fe 0.4 )HPO 4Precipitation. In the embodiments of the present disclosure, by adjusting the cut-off pH of the reaction system to 4.5 - 6 and adjusting the fluctuation range of the cut-off pH of the reaction, the molar ratio of manganese ions, iron ions and phosphate ions in the iron manganese phosphate precursor can be further accurately adjusted, thereby reducing the internal crystal impurities in the iron manganese phosphate and further improving the purity of the iron manganese phosphate.

[0088] In some embodiments, the mass concentration of the antioxidant in the aqueous solution containing the antioxidant can be 0.5% - 1.5%.

[0089] When the iron manganese hydroxide slurry is mixed with the aqueous solution containing the antioxidant, the oxidation of manganese ions and iron ions in the iron manganese hydroxide slurry can be reduced, and the purity of the iron manganese phosphate can be further improved.

[0090] In some embodiments, the preparation method may further include: performing impurity removal treatment on the iron manganese hydroxide slurry.

[0091] By performing impurity removal treatment on the iron manganese hydroxide, the generation of internal crystal impurities and the residue of surface impurities during the subsequent crystallization process of the iron manganese phosphate can be reduced, and thus the iron manganese phosphate with higher purity can be prepared. At the same time, the mother liquor after the reaction of the aqueous solution containing the phosphorus source and the first slurry can be recycled.

[0092] Exemplarily, the impurity removal treatment method may include filtration for impurity removal.

[0093] In some embodiments, the manganese source may include one or more of manganese sulfate, manganese chloride, manganese nitrate and manganese acetate.

[0094] In some embodiments, the iron source may include one or more of ferrous sulfate, ferrous chloride, ferrous nitrate and ferrous acetate.

[0095] In some embodiments, the acid in the acidic solution may include one or more of sulfuric acid, hydrochloric acid, nitric acid and ascorbic acid.

[0096] In some embodiments, the base source may include one or more of sodium hydroxide and potassium hydroxide.

[0097] In some embodiments, the antioxidant may include one or more of ascorbic acid and isoascorbic acid.

[0098] In some embodiments, the phosphorus source may include one or more of phosphoric acid, sodium dihydrogen phosphate and potassium dihydrogen phosphate.

[0099] In some embodiments, the lithium source may include one or more of lithium carbonate, lithium phosphate, lithium hydroxide, lithium dihydrogen phosphate, lithium nitrate and lithium acetate.

[0100] [Iron Manganese Phosphate Precursor] The present disclosure provides a precursor of iron manganese phosphate, and the chemical formula of the precursor of iron manganese phosphate is (Mn x Fe (1-x) ) 3 (PO 4 ) y ·nH 2 O, where 0 < x < 1.00, 2.00 ≤ y ≤ 2.01, 0 ≤ n ≤ 10; the precursor of iron manganese phosphate includes primary particles and secondary particles formed by the aggregation of primary particles; the primary particles include flaky particles, and the secondary particles include spherical particles.

[0101] In some embodiments, the volume particle size distribution Dv50 of the precursor of iron manganese phosphate can be 36 - 44 μm.

[0102] When the volume particle size distribution Dv50 of the precursor of iron manganese phosphate is within the above range, it is convenient to filter it, and at the same time, impurities such as sodium ions and sulfate ions remaining after the filtration of iron manganese hydroxide can be further removed.

[0103] In some embodiments, the mass content of sodium element in the precursor of iron manganese phosphate can be less than or equal to 35 ppm.

[0104] In some embodiments, the mass content of sulfur element in the iron manganese phosphate can be less than or equal to 110 ppm.

[0105] [Lithium iron manganese phosphate] The present disclosure provides a lithium iron manganese phosphate, which is prepared by using the above-mentioned precursor of iron manganese phosphate.

[0106] [Positive electrode plate] In addition, the present disclosure provides a positive electrode plate, which includes a positive electrode current collector and a positive electrode film layer located on at least one surface of the positive electrode current collector. The positive electrode film layer includes a positive electrode active material, and the positive electrode active material includes the above-mentioned lithium iron manganese phosphate.

[0107] In some embodiments, the positive electrode active material may further include one or more of lithium transition metal oxides and their modified materials, lithium-containing phosphates and their modified materials, lithium titanate, sulfur, selenium, and tellurium.

[0108] Optionally, the lithium transition metal oxide may include, but is 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 lithium-rich manganese-based materials.

[0109] Optionally, the lithium-containing phosphate may include, but is not limited to, one or more of lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, and a composite material of lithium iron manganese phosphate and carbon.

[0110] In some embodiments, in order to further improve the energy density of the battery cell, the positive electrode active material may further include one or more of lithium transition metal oxides and their modified materials having the general formula Li a Ni b Co c M d O e A f where 0.8 ≤ a ≤ 1.2, 0.5 ≤ b < 1, 0 < c < 1, 0 < d < 1, 1 ≤ e ≤ 2, 0 ≤ f ≤ 1, M may include one or more of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, and B, and A may include one or more of N, F, S, and Cl.

[0111] As an example, the positive electrode active material may include, but is not limited to, LiCoO 2 , LiNiO 2 , LiMnO 2 , LiMn 2 O 4 , LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 (abbreviated as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (abbreviated as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O 2 (abbreviated as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (abbreviated as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O 2 (abbreviated as NCM811), LiNi 0.83 Mn 0.08 Co 0.07 O 2 (abbreviated as Ni83), LiNi 0.90 Mn 0.05 Co 0.05 O 2 (abbreviated as Ni90), LiNi 0.94 Mn 0.03 Co 0.03 O 2 (abbreviated as Ni94), LiNi 0.96 Co0.02 Mn 0.02 O 2 (abbreviated as Ni96), LiNi 0.80 Co 0.15 Al 0.05 O 2 、LiFePO 4 、LiMnPO 4 and one or more of their respective modified materials.

[0112] The modified materials of the above-mentioned cathode active materials can be doping modification and / or surface coating modification of the cathode active materials.

[0113] During the charge and discharge process of the battery cell, the insertion and extraction and consumption of Li will occur, and the molar content of Li is different when the battery cell is discharged to different states. In the listing of the cathode active materials in the present disclosure, the molar content of Li is the initial state of the material, that is, the state before feeding. When the cathode active material is applied to the battery cell, after charge and discharge cycles, the molar content of Li will change. In the listing of the cathode active materials in the present disclosure, the molar content of O is only the theoretical state value. The release of oxygen from the lattice will cause the molar content of O to change, and the actual molar content of O will also fluctuate.

[0114] In some embodiments, the cathode film layer may further include a cathode binder, and the cathode binder may include, but is not limited to, one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0115] In some embodiments, the cathode film layer may further include a cathode conductive agent, and the cathode conductive agent may include, but is not limited to, one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, carbon nanofibers, and vapor-grown carbon fibers (VGCF).

[0116] In some embodiments, the positive electrode current collector can be a metal foil, a conductive polymer material, a carbon material, or a composite current collector. For example, as the metal foil, pure metals, alloys, and metals with surface treatment can be used, including but not limited to stainless steel, copper, aluminum, nickel, titanium, silver, etc. The composite current collector can include a polymer material substrate and a metal material layer formed on at least one surface of the polymer material substrate. As an example, the metal material can include one or more of, but is not limited to, aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material substrate can include one or more of, but is not limited to, polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE). The composite current collector can be formed by forming a metal material on the polymer material substrate.

[0117] The positive electrode film layer is usually formed by coating the positive electrode paste on the positive electrode current collector and then drying and cold pressing. The positive electrode paste is usually formed by dispersing the positive electrode active material, the positive electrode conductive agent, the positive electrode binder, and any other components in a solvent and stirring evenly. The solvent can be N-methylpyrrolidone (NMP), but is not limited thereto.

[0118] In some embodiments, the battery cell further includes a negative electrode plate, a separator, and an electrolyte.

[0119] [Negative electrode plate] The structure and composition of the negative electrode plate can be selected according to the type of the battery cell, and the embodiments of the present disclosure do not limit this.

[0120] In some embodiments, the negative electrode plate can include a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector and including a negative electrode active material. For example, the negative electrode current collector has two opposite surfaces in its own thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0121] The negative electrode active material can be a negative electrode active material known in the art for battery cells. As an example, the negative electrode active material can include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, mesophase microcarbon beads, silicon-based materials, and tin-based materials, etc. The silicon-based materials can include at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based materials can include at least one of elemental tin, tin oxides, and tin alloys. However, the present disclosure is not limited to these materials, and other conventional materials that can be used as the negative electrode active material of battery cells can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0122] In some embodiments, the negative electrode film layer may further include a negative electrode conductive agent. As an example, the negative 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.

[0123] In some embodiments, the negative electrode film layer may further include a negative electrode binder. As an example, the negative electrode binder may include, but is not limited to, one or more of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-based acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0124] In some embodiments, the negative electrode film layer may further include other additives. As an example, the other additives may include thickeners, such as sodium carboxymethyl cellulose (CMC), PTC thermistor materials, and the like.

[0125] The negative electrode film layer is generally formed by coating a negative electrode slurry on a negative electrode current collector and then drying and cold pressing. The negative electrode slurry is generally formed by dispersing a negative electrode active material, a negative electrode conductive agent, a negative electrode binder, and other optional additives in a solvent and stirring evenly. The solvent may be N-methylpyrrolidone (NMP) or deionized water, but is not limited thereto.

[0126] The negative electrode sheet does not exclude other additional functional layers other than the negative electrode film layer. For example, in some embodiments, the negative electrode sheet may further include a conductive bottom 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 sheet may further include a protective layer covering the surface of the negative electrode film layer.

[0127] In some embodiments, the negative electrode sheet may include a negative electrode current collector and a metal layer disposed on at least one surface of the negative electrode current collector, and the metal material in the metal layer may include one or more of lithium metal and lithium alloys.

[0128] The lithium alloy may be an alloy formed by metallic lithium and other metal elements or non-metal elements. As an example, the other metal elements in the lithium alloy may include one or more elements of tin, zinc, aluminum, magnesium, silver, gold, gallium, indium, and platinum, and the non-metal elements in the lithium alloy may include one or more elements of boron, carbon, and silicon.

[0129] In some embodiments, the negative electrode sheet may be a lithium sheet (foil) or a lithium alloy sheet (foil).

[0130] In some embodiments, the negative electrode sheet may include a negative current collector and does not include a metal layer, thereby assembling to form a non-negative lithium metal battery cell. During the cyclic charge and discharge process of the non-negative lithium metal battery cell, lithium in the positive electrode will precipitate and strip in the form of lithium metal on the negative electrode side.

[0131] In some embodiments, the negative current collector may include a metal foil, a conductive polymer material, a carbon material, or a composite current collector. As an example of the metal foil, pure metals, alloys, and metals with surface treatment can be used, including but not limited to stainless steel, copper, aluminum, nickel, titanium, or silver, etc. 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 not limited to one or more of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, aluminum, aluminum alloy, silver, and silver alloy. As an example, the polymer material may include but not limited to one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE). The composite current collector can be formed by forming a metal material on a polymer material substrate.

[0132] In some embodiments, the negative electrode sheet may use a porous metal. The porous metal can be porous nickel, porous copper, porous aluminum, porous alloy, or porous carbon, etc. When the porous metal is used as the negative electrode sheet, the negative electrode active material may not be provided on the surface of the porous metal, and of course, the negative electrode active material may also be provided.

[0133] As an example, the negative electrode active material can be filled and / or deposited in the negative current collector.

[0134] [Separator membrane] In some embodiments, the separator membrane is disposed between the positive electrode and the negative electrode. The separator membrane of the embodiments of the present disclosure can be a porous structure separator membrane with good chemical stability and mechanical stability.

[0135] As an example, the main material of the separator membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic. The separator membrane can be a single-layer thin film or a multi-layer composite thin film, without particular limitation. When the separator membrane is a multi-layer composite thin film, the materials of each layer can be the same or different, without particular limitation.

[0136] Optionally, an inorganic particle coating, an organic particle coating, or an organic / inorganic composite coating can also be coated on the surface of the separator membrane.

[0137] [Electrolyte] The battery cell includes an electrolyte, which plays a role in conducting ions between the positive and negative electrodes. The embodiments of the present disclosure do not specifically limit the type of the electrolyte, and it can be selected according to requirements. For example, the electrolyte may include one or more of a solid electrolyte, a gel electrolyte, and a liquid electrolyte (i.e., an electrolyte solution).

[0138] In some embodiments, the electrolyte uses an electrolyte solution, and the electrolyte solution includes an electrolyte salt and a solvent.

[0139] The type of the electrolyte salt is not specifically limited and can be selected according to actual requirements.

[0140] In some embodiments, the electrolyte salt may include, but is not limited to, lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium perchlorate (LiClO 4 ), lithium hexafluoroarsenate (LiAsF 6 ), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(oxalato)borate (LiBOB), lithium difluorophosphate (LiPO 2 F 2 ), lithium difluoro(dioxalato)phosphate (LiDFOP), and lithium tetrafluoro(oxalato)phosphate (LiTFOP), or one or more thereof.

[0141] The type of the solvent is not specifically limited and can be selected according to actual requirements.

[0142] In some embodiments, the solvent may include at least one of ethylene carbonate, propylene carbonate (PPC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), 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 diethyl sulfone (ESE). The solvent may also be an ether solvent. The ether solvent may include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether, and crown ether.

[0143] In some embodiments, the electrolyte may also optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery performance, such as additives for improving the overcharge / quick charge performance of battery cells, additives for improving the high-temperature performance of battery cells, additives for improving the low-temperature performance of battery cells, etc.

[0144] Among them, the gel electrolyte includes a polymer as a backbone network and can be used in combination with an ionic liquid-lithium salt.

[0145] Among them, the solid electrolyte includes a polymer solid electrolyte, an inorganic solid electrolyte, and a composite solid electrolyte.

[0146] As an example, the polymer of the polymer solid electrolyte may include polyethers (polyethylene oxide), polysiloxanes, polycarbonates, polyacrylonitriles, polyvinylidene fluorides, polymethyl methacrylates, single-ion polymers, polyionic liquids, cellulose, etc.

[0147] As an example, the inorganic solid electrolyte can be one or more of oxide solid electrolytes (crystalline perovskite, lithium superionic conductor, garnet, amorphous LiPON film), sulfide solid electrolytes (crystalline lithium superionic conductor, amorphous sulfide), and halide solid electrolytes, nitride solid electrolytes, and hydride solid electrolytes.

[0148] As an example, the composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to the polymer solid electrolyte.

[0149] In some embodiments, the battery cell may also include an outer package. The outer package can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package can also be a soft package, such as a pouch soft package. The material of the soft package can be plastic, such as one or more of aluminum plastic film, polypropylene, polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0150] The preparation method of the battery cell is well-known. In some embodiments, the positive electrode sheet, the separator, the negative electrode sheet, and the electrolyte can be assembled to form a battery cell. As an example, the positive electrode sheet, the separator, and the negative electrode sheet can be formed into an electrode assembly by a winding process. Exemplarily, the positive electrode sheet, the separator, and the negative electrode sheet are wound on a winding mandrel to form a cylindrical structure. After the winding mandrel is removed, the cylindrical structure is flattened to form a wound battery core. The electrode assembly is placed in the outer package, dried, and then the above-mentioned electrolyte is injected. After processes such as vacuum packaging, standing, and formation, a battery cell is obtained.

[0151] The battery cell mentioned in the embodiments of the present disclosure can independently achieve the function of charge and discharge. The battery cell can be in a cuboid shape or other shapes. AsFigure 1 The battery cell 5 with a cuboid structure is taken as an example.

[0152] In the embodiments of the present disclosure, the battery apparatus mentioned may include one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly may include a plurality of battery cells, and the plurality of battery cells are connected in series, parallel, or in a combined series-parallel manner through a busbar component.

[0153] In some embodiments, the battery cell assembly is generally formed by arranging a plurality of battery cells.

[0154] As an example, the battery cell assembly may be a battery module, and the battery module is formed by arranging and fixing a plurality of battery cells to form an independent module. As an example, the battery module may be formed by bundling a plurality of battery cells with cable ties.

[0155] In some embodiments, the battery apparatus may be a battery pack, and the battery pack includes a box body and one or more battery cell assemblies, and the battery cell assemblies are accommodated in the box body.

[0156] As an example, the battery cell assembly may be a battery module, and the battery cell assembly may be accommodated in the box body by fixing the battery module in the box body.

[0157] As an example, the battery cell assembly may also be accommodated in the box body by directly fixing a plurality of battery cells to the box body.

[0158] As an example, the box body may include a first box body and a second box body. The first box body and the second box body are snapped together so that a closed space is formed inside the box body to accommodate the battery cell assembly. Here, "closed" means covered or closed, which can be sealed or non-sealed. The first box body may be a top cover or a bottom plate.

[0159] As an example, the box body may include a top cover, a frame, and a bottom plate. The top cover and the bottom plate are respectively connected to the frame so that a closed space is formed inside the box body to accommodate the battery cell assembly.

[0160] In some embodiments, the box body may be a part of the chassis structure of a vehicle. For example, a part of the box body may become at least a part of the floor of the vehicle, or a part of the box body may become at least a part of the crossbeam and longitudinal beam of the vehicle.

[0161] The technical solutions described in the embodiments of the present disclosure are applicable to various electrical devices using battery cells and battery devices, such as, but not limited to, mobile devices (such as mobile phones, tablet computers, laptop computers, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc. The battery cells and battery devices are used to store or provide electrical energy.

[0162] Figure 2 It is a schematic diagram of an electrical device as an example. The electrical device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc.

[0163] Embodiment The following embodiments describe the content of the present disclosure in more detail. These embodiments are only for illustrative purposes, because various modifications and changes within the scope of the present disclosure are obvious to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized according to conventional methods and can be used directly without further treatment, and all instruments used in the embodiments are commercially available.

[0164] Test part (1)Determination of the microscopic morphology, elemental composition and distribution of iron manganese hydroxide and iron manganese hydrogen phosphate The scanning electron microscope (SEM) was used to observe the microscopic morphology of iron manganese hydroxide and iron manganese hydrogen phosphate, and the energy dispersive spectrometer (EDS) was used to observe the elemental composition and distribution of iron manganese hydroxide and iron manganese hydrogen phosphate.

[0165] (2)Determination of element content in iron manganese hydroxide and iron manganese hydrogen phosphate Weighed 0.100 g of the sample into a 50 mL centrifuge tube, added 4 ml of nitric acid (volume ratio 1:1) + 2 ml of perchloric acid (volume ratio 1:1), heated and digested in a graphite digestion instrument at 120 °C for 0.5 h, and fixed the volume with a 100 mL volumetric flask; then pipetted 1 mL into a 100 mL volumetric flask to fix the volume to obtain the test solution. The inductively coupled plasma spectrometer (ICP-OES) was used to determine the contents of manganese, iron, and phosphorus in the test solution, calculate the element ratio in the sample, and use the same method to determine the content of impurity elements in the sample.

[0166] Example 1 (1)Preparation of iron manganese hydroxide Dissolve 3.20 mol of ferrous sulfate heptahydrate and 4.80 mol of manganese sulfate monohydrate in deionized water and adjust the volume to 4000 mL. The total molar concentration of ferrous ions and manganese ions is 2 mol / L. Add appropriate amount of concentrated H 2 SO 4 , obtaining a first mixed solution.

[0167] Add 16.80 mol of sodium hydroxide to pure water, stir to dissolve, and adjust the volume to 4000 mL. The concentration of sodium hydroxide is 4.2 mol / L. When the solution temperature is close to room temperature, add 0.16 mol of ethylenediaminetetraacetic acid (EDTA). The amount of EDTA added is 2% of the total molar amount of ferrous ions and manganese ions. Stir until completely dissolved to obtain a second mixed solution.

[0168] Under the conditions of a temperature of 60° C. and a stirring speed of 800 rpm, nitrogen was continuously introduced into the bottom liquid of the reaction kettle containing ethylenediaminetetraacetic acid, and an appropriate amount of sodium hydroxide was added to adjust the pH value of the bottom liquid to be stable within the range of 10.00±0.05 to obtain an alkaline solution containing a complexing agent, wherein the concentration of ethylenediaminetetraacetic acid was 0.02 mol / L.

[0169] The first mixed solution and the second mixed solution were respectively injected into the above-mentioned reactor by peristaltic pumps in parallel, the feeding rate of the first mixed solution was set to 15.00 mL / min, and the feeding rate of the second mixed solution was adjusted in linkage to stabilize the reaction pH within the range of 10.00±0.05, wherein the feeding cut-off condition was that the first mixed solution was completely used up. After the feeding was completed, the stirring rate remained unchanged, and the aging was continued for 30 minutes to obtain ferromanganese hydroxide slurry.

[0170] After the ferromanganese hydroxide slurry is cooled to room temperature, it is washed with pure water and subjected to multiple solid-liquid separations to remove impurity ions such as sodium and sulfate to obtain the impurity-free ferromanganese hydroxide wet material.

[0171] (2) Preparation of ferromanganese phosphate The above-mentioned manganese ferrohydroxide wet material is placed in a reactor, and deionized water containing ascorbic acid is added, the mass concentration of ascorbic acid in the deionized water is 1%, the mass ratio of the wet material to the deionized water is 1:1, and the stirring speed is adjusted to ≥600rpm to form a first slurry.

[0172] 5.60 mol of phosphoric acid with a mass fraction of 85% was mixed with 2000 mL of deionized water and stirred evenly to prepare an aqueous solution containing a phosphorus source. This solution was added to the reaction kettle containing the first slurry at a feeding rate of 8.67 mL / min. To ensure that metal ions are not oxidized during the reaction, cooling water was introduced into the jacket of the reaction kettle, and at the same time, the temperature of the reaction system was ensured not to exceed 30 °C. The feeding cut-off condition was that the pH value of the reaction system was stable at 5.30 ± 0.05, the stirring rate remained unchanged, and aging was continued for 1 h to obtain a slurry containing iron manganese phosphite.

[0173] The above slurry containing iron manganese phosphite was subjected to solid-liquid separation and placed in a vacuum drying oven. High-temperature drying was carried out at a drying temperature of 90 °C while maintaining a vacuum pressure of -0.01 MPa to obtain a high-purity iron manganese phosphite precursor.

[0174] (3)Preparation of lithium iron manganese phosphate The iron manganese phosphite precursor was mixed with lithium phosphate, carbon source glucose, and dopant titanium dioxide. After ball milling, spraying, and sintering, a lithium iron manganese phosphate cathode active material was obtained.

[0175] Example 2 The preparation method of iron manganese hydroxide was the same as that in Example 1, except that the pH of the solution during the single-phase coprecipitation reaction was 9.6.

[0176] Example 3 The preparation method of iron manganese hydroxide was the same as that in Example 1, except that the pH of the solution during the single-phase coprecipitation reaction was 9.8.

[0177] Example 4 The preparation method of iron manganese hydroxide was the same as that in Example 1, except that the pH of the solution during the single-phase coprecipitation reaction was 10.2.

[0178] Example 5 The preparation method of iron manganese hydroxide was the same as that in Example 1, except that the pH of the solution during the single-phase coprecipitation reaction was 10.4.

[0179] Comparative Example 1 The preparation method of the iron manganese hydrogen phosphate precursor was the same as that in Example 1, except for the following differences.

[0180] (1)16.80 mol of sodium hydroxide was added to pure water, stirred and dissolved. When the solution temperature was close to room temperature, 8.40 mol of ammonia water (mass concentration of 20%) was added, and the volume was fixed to 4000 mL to obtain a second mixed solution, where the concentration of sodium hydroxide was 4.2 mol / L and the concentration of ammonia water was 2.1 mol / L; (2) Under the conditions of a temperature of 60 °C and a stirring speed of 800 rpm, nitrogen was continuously introduced into the bottom liquid of the reaction kettle containing ammonia water, and the pH value of the bottom liquid was adjusted to be stable within the range of 10.00 ± 0.05 to obtain an alkaline solution containing a complexing agent, where the concentration of ammonia water was 1.05 mol / L.

[0181] The particle sizes of the iron manganese hydroxide prepared in Examples 1-5 and Comparative Example 1, the impurity contents in the iron manganese hydroxide, and the contents of the remaining Mn and Fe in the reaction mother liquor are shown in Table 1.

[0182] Table 1

[0183] From the test results in Table 1, it can be seen that in Examples 1-5, as the pH of the single-phase coprecipitation reaction increases, it is more conducive to the nucleation of iron manganese hydroxide particles, and the smaller the particle size of the obtained iron manganese hydroxide. However, at the same time, problems such as difficult filtration of the slurry and high internal impurity content will also be caused. Considering comprehensively the effects of the particle size on the antioxidant property of the particles, the impurity content, the raw material utilization rate, and the preparation of iron manganese hydrogen phosphate in the future, the pH value of the single-phase coprecipitation reaction can be controlled within the range of 9.80 - 10.20.

[0184] Example 6 The preparation method of iron manganese hydroxide was the same as that in Example 1, except that the addition amount of the complexing agent ethylenediaminetetraacetic acid in the second mixed solution was 1% of the total molar amount of ferrous ions and manganese ions.

[0185] Example 7 The preparation method of iron manganese hydroxide was the same as that in Example 1, except that the addition amount of the complexing agent ethylenediaminetetraacetic acid in the second mixed solution was 1.5% of the total molar amount of ferrous ions and manganese ions.

[0186] Example 8 The preparation method of iron manganese hydroxide was the same as that in Example 1, except that the addition amount of the complexing agent ethylenediaminetetraacetic acid in the second mixed solution was 2.5% of the total molar amount of ferrous ions and manganese ions.

[0187] Example 9 The preparation method of iron manganese hydroxide was the same as that in Example 1, except that the addition amount of the complexing agent ethylenediaminetetraacetic acid in the second mixed solution was 3% of the total molar amount of ferrous ions and manganese ions.

[0188] The particle sizes of the iron manganese hydroxide prepared in Example 1 and Examples 6-9, the impurity contents in the iron manganese hydroxide, and the contents of the remaining Mn and Fe in the reaction mother liquor are shown in Table 2.

[0189] Table 2

[0190] As can be seen from Table 2, with the increase in the dosage of the complexing agent, the particle size of iron manganese hydroxide first increases and then gradually stabilizes; at the same time, the impurity content in iron manganese hydroxide first decreases and then increases, indicating that the dosage of the complexing agent is not necessarily the more the better. In addition, excessive dosage of the complexing agent will increase the difficulty of separating impurities from iron manganese hydroxide and cause excessive residual amounts of manganese ions and iron ions in the mother liquor. When the dosage of the complexing agent is in the range of 1.5% - 2.5%, the impurity content in iron manganese hydroxide can be further reduced, as well as the contents of Mn and Fe in the mother liquor.

[0191] Example 10 The preparation method of manganese iron hydrogen phosphate is the same as that of Example 1, except that the reaction between the aqueous solution containing the phosphorus source and the first slurry ends at a pH of 6.00.

[0192] Example 11 The preparation method of manganese iron hydrogen phosphate is the same as that of Example 1, except that the reaction between the aqueous solution containing the phosphorus source and the first slurry ends at a pH of 5.50.

[0193] Example 12 The preparation method of manganese iron hydrogen phosphate is the same as that of Example 1, except that the reaction between the aqueous solution containing the phosphorus source and the first slurry ends at a pH of 5.00.

[0194] Example 13 The preparation method of manganese iron hydrogen phosphate is the same as that of Example 1, except that the reaction between the aqueous solution containing the phosphorus source and the first slurry ends at a pH of 4.50.

[0195] The mass contents of Mn and Fe and the impurity content in the manganese iron hydrogen phosphate prepared in Example 1, Examples 10 - 13 and Comparative Example 1 are shown in Table 3.

[0196] Table 3

[0197] The molar ratios of Mn / (Mn + Fe), Fe / (Mn + Fe) and (Mn + Fe) / (PO 4 ) in the manganese iron hydrogen phosphate prepared in Example 1, Examples 10 - 13 and Comparative Example 1 are shown in Table 4.

[0198] Table 4

[0199] From the test results in Table 3 and Table 4, it can be seen that as the reaction between the aqueous solution containing the phosphorus source and the first slurry ends at a gradually decreasing pH, the ratio of (Mn + Fe) / (PO 4 ) first gradually approaches 1.50 and then gradually deviates from 1.5. The reason may be that the reaction precipitate can be composed of (Mn 0.6 Fe 0.4)(OH) 2 、(Mn 0.6 Fe 0.4 ) 3 (PO 4 ) 2 and one or two of (Mn 0.6 Fe 0.4 )HPO 4 . The phosphating reaction is carried out by adding acid to base. (Mn 0.6 Fe 0.4 )(OH) 2 gradually reacts to form (Mn 0.6 Fe 0.4 ) 3 (PO 4 ) 2 . When (Mn 0.6 Fe 0.4 )(OH) 2 completely reacts, the ratio of (Mn + Fe) / (PO 4 ) is close to 1.50. If phosphoric acid is continuously added, the excessive phosphoric acid will react with the newly formed (Mn 0.6 Fe 0.4 ) 3 (PO 4 ) 2 again to form (Mn 0.6 Fe 0.4 )HPO 4 precipitate. At this time, the ratio of (Mn + Fe) / (PO 4 ) will gradually deviate from 1.50 and tend to 1.00.

[0200] In Example 1, Examples 10 - 13 and Comparative Example 1, the molar ratio of ferrous ions to manganese ions in the first mixed solution is 2:3, but the molar ratio of ferrous ions to manganese ions in the iron manganese hydrogen phosphate obtained in Comparative Example 1 significantly deviates from 2:3. This shows that the preparation method of the embodiments of the present disclosure can accurately adjust the molar ratio of manganese ions to iron ions in the iron manganese phosphate precursor, and an iron manganese phosphate precursor with higher purity can be prepared.

[0201] As can be seen from Figure 3 , the morphology of the iron manganese hydroxide particles is uniform and no obvious difference is seen. As can be seen from Figure 4 and Figure 5 , the primary particles of iron manganese phosphate are in a nano - sheet structure with uniform thickness, and the secondary particles are in a spherical - like structure. As can be seen from Figures 6 - 10 , the distribution of Mn, Fe, P, and O elements in the iron manganese phosphate is uniform. Combining with the ICP element content determination in Table 3 and Table 4, it can be fully shown that the embodiments of the present disclosure have successfully prepared iron manganese phosphate particles with higher purity, and the ratio of manganese to iron can be changed as required.

[0202] It should be noted that the present disclosure is not limited to the above embodiments. The above embodiments are only examples, and embodiments having the same constitution and the same effect as the technical idea within the scope of the technical solution of the present disclosure are included in the technical scope of the present disclosure. In addition, within the scope not departing from the gist of the present disclosure, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways constructed by combining some constituent elements in the embodiments are also included in the scope of the present disclosure.

Claims

1. A method for preparing lithium manganese iron phosphate, characterized in that: include: Mixing a divalent manganese source, a divalent iron source and an acidic solution to obtain a first mixed solution; Mixing an aqueous solution containing an alkali source with a complexing agent to obtain a second mixed solution, wherein the complexing agent includes an aminocarboxylic acid compound; The first mixed solution and the second mixed solution are added to an alkaline solution containing a complexing agent in parallel to perform a single-phase coprecipitation reaction to obtain a ferromanganese hydroxide slurry; Mixing the ferromanganese hydroxide slurry with an aqueous solution containing an antioxidant to obtain a first slurry; Mixing the aqueous solution containing a phosphorus source with the first slurry, and reacting until the pH of the system is 4.5-6 to obtain a ferromanganese phosphate precursor; The manganese ferrophosphate precursor is mixed with a lithium source and then sintered to obtain a manganese ferrophosphate lithium positive electrode active material.

2. The preparation method according to claim 1, characterized in that: The preparation method comprises: mixing an aqueous solution containing a phosphorus source with the first slurry, reacting until the pH value of the system is 5.2-5.4, and obtaining a ferromanganese phosphate precursor.

3. The preparation method according to claim 1, characterized in that: The aminocarboxylic acid compound includes one or more of ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetate, tetrasodium ethylenediaminetetraacetate, diethyltriaminepentaacetic acid, aminotriacetic acid and ethylenediaminediacetic acid.

4. The preparation method according to claim 1, characterized in that: The amount of the complexing agent added to the second mixed solution is 1%-3% of the total molar amount of ferrous ions and manganese ions; and / or, The concentration of the complexing agent in the alkaline solution containing the complexing agent is 0.01-0.05 mol / L.

5. The preparation method according to claim 1, characterized in that: The single-phase coprecipitation reaction satisfies one or more of the following conditions (1)-(3): (1) The pH value of the solution during the single-phase coprecipitation reaction is 9.6-10.4; (2) The single-phase coprecipitation reaction time is 270-300 min; (3) The temperature of the single-phase coprecipitation reaction is 55-65°C.

6. The preparation method according to claim 1, characterized in that: Mixing the aqueous solution containing a phosphorus source with the first slurry includes: adding the aqueous solution containing a phosphorus source into the first slurry.

7. The preparation method according to claim 1, characterized in that: The preparation method further comprises: subjecting the ferromanganese hydroxide slurry to an impurity removal treatment.

8. The preparation method according to claim 1, characterized in that: The manganese source includes one or more of manganese sulfate, manganese chloride, manganese nitrate and manganese acetate; and / or, The iron source includes one or more of ferrous sulfate, ferrous chloride, ferrous nitrate and ferrous acetate; and / or, The acid in the acidic solution includes one or more of sulfuric acid, hydrochloric acid, nitric acid and ascorbic acid; and / or, The alkali source includes one or more of sodium hydroxide and potassium hydroxide; and / or, The antioxidant includes one or more of ascorbic acid and isoascorbic acid; and / or, The phosphorus source includes one or more of phosphoric acid, sodium dihydrogen phosphate, and potassium dihydrogen phosphate.

9. A ferromanganese phosphate precursor, characterized in that: The chemical formula of the manganese ferrophosphate precursor is (Mn x Fe (1-x) )3(PO4) y ·nH2O, 0<x<1.00, 2.00≤y≤2.01, 0≤n≤10; The ferromanganese phosphate precursor includes primary particles and secondary particles formed by agglomeration of the primary particles; The primary particles include flake particles, and the secondary particles include spherical particles.

10. The ferromanganese phosphate precursor according to claim 9, characterized in that: The ferromanganese phosphate precursor satisfies one or more of the following conditions (1)-(3): (1) The volume particle size distribution Dv50 of the ferromanganese phosphate precursor is 36-44 μm; (2) The mass content of sodium in the ferromanganese phosphate precursor is less than or equal to 35 ppm; (3) The mass content of sulfur in the ferromanganese phosphate is less than or equal to 110 ppm.

11. A lithium manganese iron phosphate, characterized in that: The method is prepared by using the ferromanganese phosphate precursor according to claim 9 or 10.

12. A battery cell, characterized in that: Including the lithium manganese iron phosphate as described in claim 11.

13. A battery device, characterized in that: The invention comprises a plurality of battery cells as claimed in claim 12.

14. An electrical device, characterized in that: Includes the battery cell according to claim 12 or the battery device according to claim 13.

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