Preparation methods of ferromanganese phosphate, ferromanganese phosphate, cathode materials and batteries

Abstract

The present invention belongs to the technical field of battery materials, and mainly discloses a preparation method of ferromanganese phosphate, including: step S1, adding a complexing agent and an oxidant to a mixed solution A of a manganese source, an iron source, and a phosphorus source to obtain a mixed solution B; step S2, dividing the mixed solution B into two parts, a mixed solution B-1 and a mixed solution B-2; step S3, adjusting the pH value of the mixed solution B-1 to 2.0-5.0, heating to 90-100 DEG C, and keeping warm to obtain a slurry I; step S4, adding a mixed solution B-2 to the slurry I, adjusting the pH value of the system to 1-5, keeping warm at 60-100 DEG C to obtain a slurry II; step S5, carrying out solid-liquid separation of the slurry II, drying, screening, and calcining the obtained solid phase to obtain ferromanganese phosphate. In the process of preparing ferromanganese phosphate, no toxic and harmful reagents are used, and the ferromanganese phosphate is safe and environmentally friendly, which is conducive to industrial application; and the prepared ferromanganese phosphate has a loose and porous inner layer and a dense and compact outer layer.

Description

Technical Field

[0001] This invention belongs to the field of battery materials technology, and specifically discloses manganese iron phosphate, its preparation method and application. Background Technology

[0002] Lithium manganese iron phosphate (LMP) is a battery cathode material that not only inherits the safety and stability advantages of lithium iron phosphate but also boasts higher energy density, lower cost, and longer lifespan. The precursor material for LMP is iron manganese phosphate.

[0003] CN115321507A discloses a method for co-precipitating ferric manganese phosphate. The method involves preparing ferricyanide solution, manganese salt solution, and a mixed solution of phosphoric acid and perchloric acid. These solutions are then added concurrently to the base liquid to initiate the reaction. When the reactants reach the target particle size, solid-liquid separation is performed to obtain a precipitate. The precipitate is washed and dried to obtain ferric manganese phosphate. The method utilizes ferricyanide to inhibit the direct precipitation of ferric ions and employs perchloric acid and phosphoric acid to break down the cyanide, thus slowing down the precipitation rate of ferric phosphate and achieving co-precipitation of iron and manganese, improving the uniformity of the iron-manganese mixture. However, the use of toxic cyanide and the strong oxidizing agent perchloric acid makes it unsuitable for industrial applications. Summary of the Invention

[0004] To address the problems existing in the prior art, the first objective of this invention is to provide a safe and environmentally friendly method for preparing ferromanganese phosphate that produces uniform precipitation of iron and manganese; the second objective of this invention is to provide ferromanganese phosphate and its applications.

[0005] To address the above problems, the present invention proposes the following specific technical solutions.

[0006] First, the present invention provides a method for preparing ferric manganese phosphate, comprising:

[0007] Step S1: Add a complexing agent and an oxidizing agent to a mixed solution A containing manganese, iron, and phosphorus sources to obtain a mixed solution B;

[0008] Step S2: Divide the mixed solution B into two parts: mixed solution B-1 and mixed solution B-2;

[0009] Step S3: Adjust the pH of mixed solution B-1 to 2.0~5.0, heat to 90~100℃, keep warm, and obtain slurry I;

[0010] Step S4: Add mixed solution B-2 to slurry I, adjust the pH of the system to 1~5, and keep it at 60~100℃ to obtain slurry II;

[0011] Step S5: The slurry II is subjected to solid-liquid separation, and the solid phase obtained by drying, sieving, and calcining is obtained to obtain manganese iron phosphate.

[0012] In a further preferred embodiment, the total molar concentration of manganese and iron in the mixed solution A is 0.2~2.0 mol / L.

[0013] In a further preferred embodiment, the molar ratio of manganese to iron in the mixed solution A is 1 to 2:1.

[0014] In a further preferred embodiment, the ratio of the molar amount of the complexing agent to the total molar amount of iron and manganese is 1 to 2:1.

[0015] In a further preferred embodiment, the ratio of the molar amount of the oxidant to the total molar amount of iron and manganese is 1 to 1.5:1.

[0016] In a further preferred embodiment, the manganese source is at least one selected from manganese sulfate, manganese nitrate, manganese chloride, manganese oxalate, and manganese acetate; the iron source is at least one selected from ferrous sulfate, ferrous nitrate, ferrous chloride, ferrous oxalate, and ferrous acetate; the phosphorus source is at least one selected from phosphoric acid, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, and sodium phosphate; and the complexing agent is sodium pyrophosphate, potassium pyrophosphate, phosphoric acid, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, ammonium phosphate, DFOB, and iron-removing manure. The oxidant is at least one of the following: vitamin, acetohydroxy acid, 2,5-diacylisohydroxamic acid, 3,4-diacylisohydroxamic acid, EDTA, disodium EDTA, sodium citrate, ammonium citrate, and potassium citrate; the oxidant is at least one of the following: hydrogen peroxide, ammonium persulfate, sodium persulfate, potassium persulfate, ozone, nitric acid, ammonium nitrate, potassium nitrate, sodium nitrate, potassium permanganate, dichromic acid, chlorine, chloric acid, hypochlorous acid, chlorite, perchloric acid, hypoiodic acid, metaperiodic acid, bromic acid, hypobromous acid, perbromous acid, ferrate, and fluorine.

[0017] In a further preferred embodiment, the volume ratio of mixed solution B-1 to mixed solution B-2 is (20~40):(80~60).

[0018] In a further preferred embodiment, in step S3, the pH value of the mixed solution B-1 is adjusted to 3.0~5.0.

[0019] In a further preferred embodiment, in step S3, the temperature is heated to 95~100°C.

[0020] In a further preferred embodiment, in step S3, the heat preservation time is 1~2 hours.

[0021] In a further preferred embodiment, in step S4, the pH of the system is adjusted to 1.5~3.0.

[0022] In a further preferred embodiment, in step S4, the temperature is maintained at 80~95℃.

[0023] In a further preferred embodiment, in step S4, the heat preservation time is 0.5~2h.

[0024] In a further preferred embodiment, in step S5, the drying temperature is 90~150℃; the calcination temperature is 200~600℃.

[0025] In a further preferred embodiment, stirring is carried out during steps S1, S3, and S4; the stirring speed is further preferred to be 100~1000 rpm.

[0026] Secondly, this invention provides a manganese iron phosphate with the general chemical formula Mn. x Fe 1-x PO4, wherein 0.1≤x≤0.9, preferably 0.4≤x≤0.8; is a secondary particle formed by the agglomeration of primary particles, and has a spherical or near-spherical structure; it includes a core and a shell, the core being loose and porous, and the shell being relatively compact.

[0027] In a further preferred embodiment, the diameter of the primary particles of the outer shell is 75~500nm; the diameter of the primary particles of the core is smaller than the diameter of the primary particles of the outer shell.

[0028] In a further preferred embodiment, the ratio of the thickness of the outer shell to the radius of the core is 0.8 to 3.0:1.

[0029] In a further preferred embodiment, the manganese iron phosphate satisfies at least one of the following conditions (a) to (c):

[0030] (a) The porosity of the core is 30-60%; preferably 40-50%;

[0031] (b) The porosity of the outer shell is 0.01~5%; preferably 0.05~2%;

[0032] (c) The porosity difference between the core and the shell is 25-60%; preferably 40-50%.

[0033] In a further preferred embodiment, the manganese iron phosphate satisfies at least one of the following conditions (d) to (f):

[0034] (d) The primary particles constituting the outer shell are dendritic or elongated;

[0035] (e) The average aspect ratio of the primary particles constituting the outer shell is 1.0 to 4.0, preferably 1.5 to 3.0;

[0036] (f) The particle size D50 of the secondary particles is 5.0~9.0μm.

[0037] Based on the same inventive concept, the manganese iron phosphate provided by the present invention can be prepared by the aforementioned preparation method.

[0038] Furthermore, the present invention provides a positive electrode material prepared from the above-described manganese iron phosphate, and provides a battery comprising the positive electrode material.

[0039] The above-described one or more technical solutions of the present invention can achieve at least one of the following beneficial effects:

[0040] The preparation method provided by this invention is simple and highly operable.

[0041] No toxic or harmful reagents are used in the preparation of manganese ferric phosphate, making it safe, environmentally friendly, and conducive to industrial application.

[0042] The preparation method provided by this invention enables MnPO4 and FePO4 to co-precipitate simultaneously, resulting in a uniform distribution of iron and manganese.

[0043] The manganese iron phosphate provided by this invention has a loose and porous inner layer and a dense and compact outer layer. Attached Figure Description

[0044] Figure 1 The image shows the XRD pattern of the manganese iron phosphate material obtained in Example 1.

[0045] Figure 2 The image shows the EDS diagrams of each element in the manganese iron phosphate material obtained in Example 1.

[0046] Figure 3 The image shows the SEM image of the manganese iron phosphate material obtained in Example 1.

[0047] Figure 4 This is a cross-sectional SEM image of the manganese iron phosphate material obtained in Example 1.

[0048] Figure 5 The image shows the XRD pattern of the manganese iron phosphate material obtained in Example 2.

[0049] Figure 6 The image shows the EDS diagrams of each element in the manganese iron phosphate material obtained in Example 2.

[0050] Figure 7 The image shows the SEM image of the manganese iron phosphate material obtained in Example 2.

[0051] Figure 8 This is a cross-sectional SEM image of the manganese iron phosphate material obtained in Example 2.

[0052] Figure 9 The image shows the XRD pattern of the manganese iron phosphate material obtained in Example 3.

[0053] Figure 10 The image shows the EDS diagrams of each element in the manganese iron phosphate material obtained in Example 3.

[0054] Figure 11 The image shows the SEM image of the manganese iron phosphate material obtained in Example 3.

[0055] Figure 12 This is a cross-sectional SEM image of the manganese iron phosphate material obtained in Example 3.

[0056] Figure 13 The image shows the XRD pattern of the manganese iron phosphate material obtained in Example 4.

[0057] Figure 14 The image shows the EDS diagrams of each element in the manganese iron phosphate material obtained in Example 4.

[0058] Figure 15 The image shows the SEM image of the manganese iron phosphate material obtained in Example 4.

[0059] Figure 16 This is a cross-sectional SEM image of the manganese iron phosphate material obtained in Example 4.

[0060] Figure 17 The image shows the XRD pattern of the manganese iron phosphate material obtained in Example 5.

[0061] Figure 18 The image shows the EDS diagrams of each element in the manganese iron phosphate material obtained in Example 5.

[0062] Figure 19 SEM image of the manganese iron phosphate material obtained in Example 5

[0063] Figure 20 This is a cross-sectional SEM image of the manganese iron phosphate material obtained in Example 5.

[0064] Figure 21 The image shows the XRD pattern of the manganese iron phosphate material obtained in Example 6.

[0065] Figure 22 The image shows the EDS diagrams of each element in the manganese iron phosphate material obtained in Example 6.

[0066] Figure 23 The image shows the SEM image of the manganese iron phosphate material obtained in Example 6.

[0067] Figure 24 This is a cross-sectional SEM image of the manganese iron phosphate material obtained in Example 6.

[0068] Figure 25 The image shows the XRD pattern of the manganese iron phosphate material obtained in Comparative Example 1.

[0069] Figure 26 The image shows the EDS diagrams of each element in the manganese iron phosphate material obtained in Comparative Example 1.

[0070] Figure 27 The image shows the SEM image of the manganese iron phosphate material obtained in Comparative Example 1.

[0071] Figure 28 The image shows a cross-sectional SEM image of the manganese iron phosphate material obtained in Comparative Example 1.

[0072] Figure 29 The image shows the XRD pattern of the manganese iron phosphate material obtained in Comparative Example 2.

[0073] Figure 30 The image shows the EDS diagrams of each element in the manganese iron phosphate material obtained in Comparative Example 2.

[0074] Figure 31 The image shows the SEM image of the manganese iron phosphate material obtained in Comparative Example 2.

[0075] Figure 32 The image shows a cross-sectional SEM image of the manganese iron phosphate material obtained in Comparative Example 2.

[0076] Figure 33 The image shows the XRD pattern of the manganese iron phosphate material obtained in Comparative Example 3.

[0077] Figure 34 The image shows the EDS diagrams of each element in the manganese iron phosphate material obtained in Comparative Example 3.

[0078] Figure 35 The image shows the SEM image of the manganese iron phosphate material obtained in Comparative Example 3.

[0079] Figure 36 The image shows a cross-sectional SEM image of the manganese iron phosphate material obtained in Comparative Example 3.

[0080] Figure 37 The image shows the XRD pattern of the manganese iron phosphate material obtained in Comparative Example 4.

[0081] Figure 38 The image shows the EDS diagrams of each element in the manganese iron phosphate material obtained in Comparative Example 4.

[0082] Figure 39 The image shows the SEM image of the manganese iron phosphate material obtained in Comparative Example 4.

[0083] Figure 40 The image shows a cross-sectional SEM image of the manganese iron phosphate material obtained in Comparative Example 4.

[0084] Figure 41 The image shows the SEM image of the manganese iron phosphate material obtained in Comparative Example 5.

[0085] Figure 42 The image shows the SEM image of the manganese iron phosphate material obtained in Comparative Example 6.

[0086] Figure 43 The image shows the SEM image of the manganese iron phosphate material obtained in Comparative Example 7.

[0087] Figure 44 The image shows the SEM image of the manganese iron phosphate material obtained in Comparative Example 8.

[0088] Figure 45 The image shows a cross-sectional SEM image of the manganese iron phosphate material obtained in Comparative Example 9.

[0089] Figure 46 The image shows the SEM image of the manganese iron phosphate material obtained in Comparative Example 10.

[0090] Figure 47 The image shows the SEM image of the manganese iron phosphate material obtained in Comparative Example 11. Detailed Implementation

[0091] First, this invention provides a method for preparing ferric manganese phosphate, comprising the following steps:

[0092] Step S1: Add a complexing agent and an oxidizing agent to a mixed solution A containing manganese, iron, and phosphorus sources to obtain a mixed solution B;

[0093] Step S2: Divide the mixed solution B into two parts: mixed solution B-1 and mixed solution B-2;

[0094] Step S3: Adjust the pH of mixed solution B-1 to 2.0~5.0, heat to 90~100℃, keep warm, and obtain slurry I;

[0095] Step S4: Add mixed solution B-2 to slurry I, adjust the pH of the system to 1~5, and keep it at 60~100℃ to obtain slurry II;

[0096] Step S5: The slurry II is subjected to solid-liquid separation, and the solid phase obtained by drying, sieving, and calcining is obtained to obtain manganese iron phosphate.

[0097] In practice, the content of manganese, iron, and phosphorus sources in mixed solution A is set according to the ratio of manganese, iron, and phosphorus in the target manganese ferric phosphate. For example, based on the chemical formula Mn... x Fe 1-x PO4 (where 0.1≤x≤0.9, preferably 0.4≤x≤0.8) is used to determine the content of manganese, iron and phosphorus sources in mixed solution A.

[0098] In some embodiments of the present invention, the total molar concentration of manganese and iron in the mixed solution A is 0.2~2.0 mol / L. More preferably, the molar ratio of manganese to iron in the mixed solution A is 1~2:1.

[0099] In practice, those skilled in the art can select appropriate manganese, iron, and phosphorus sources based on actual conditions; generally, sources that are soluble in water are sufficient. In a specific embodiment of the present invention:

[0100] The manganese source is at least one of manganese sulfate, manganese nitrate, manganese chloride, manganese oxalate, and manganese acetate.

[0101] The iron source is at least one of ferrous sulfate, ferrous nitrate, ferrous chloride, ferrous oxalate, and ferrous acetate.

[0102] The phosphorus source is at least one of phosphoric acid, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, and sodium phosphate.

[0103] In this invention, an oxidizing agent and a complexing agent are used in combination to stabilize manganese in the solution in the trivalent state. Furthermore, the amount of complexing agent and oxidizing agent used should also be based on the principle of "stabilizing manganese in the solution in the trivalent state." Based on this principle, those skilled in the art can adjust the amount of complexing agent and oxidizing agent according to actual circumstances.

[0104] In a specific embodiment of the present invention, the molar ratio of the complexing agent to the total molar ratio of iron and manganese is 1~2:1; the molar ratio of the oxidant to the total molar ratio of iron and manganese is 1~1.5:1. In this invention, if the amount of complexing agent is too high, the preparation cost increases significantly; if the amount of complexing agent is too low, incomplete complexation may result in some Mn being lost. 3+ Disproportionation to Mn 2+ With Mn 4+ Excessive oxidant dosage may result in the presence of Mn. 4+ If the amount of oxidant is too low, incomplete oxidation will occur.

[0105] For those skilled in the art, any complexing agent commonly used in the field that can perform a complexing effect can achieve the purpose of this invention. In a specific embodiment of this invention, the complexing agent is at least one selected from sodium pyrophosphate, potassium pyrophosphate, phosphoric acid, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, ammonium phosphate, DFOB, deferiprone acid, acetohydroxy acid, 2,5-diacylisohydroxyxamic acid, 3,4-diacylisohydroxyxamic acid, EDTA, disodium EDTA, sodium citrate, ammonium citrate, and potassium citrate.

[0106] It is important to note that in the preferred embodiment of the present invention, phosphoric acid is further selected as the complexing agent. Phosphoric acid can be used as both a phosphorus source and a complexing agent in this invention, and it can also be used as a pH adjuster.

[0107] Oxidizing agents are common chemicals in the art. In specific embodiments of the present invention, the oxidizing agent is at least one selected from hydrogen peroxide, ammonium persulfate, sodium persulfate, potassium persulfate, ozone, nitric acid, ammonium nitrate, potassium nitrate, sodium nitrate, potassium permanganate, dichromic acid, chlorine, chloric acid, hypochlorous acid, chlorite, perchloric acid, hypoiodic acid, metaperiodic acid, bromic acid, hypobromic acid, perbromic acid, ferrate, and fluorine. More preferably, the oxidizing agent is ammonium persulfate.

[0108] Steps S3 and S4 are also key to this invention. By employing a segmented feeding synthesis method, the supersaturation of the reaction system is controlled, and the crystal nucleation and growth process is regulated to prepare manganese iron phosphate material. Simultaneously, segmented feeding is used to control the thickness or ratio of the inner and outer layers by adjusting the amount of solution used in each stage. Controlling the temperature and pH value of the synthesis process yields a manganese iron phosphate material with a porous inner layer and a dense outer layer. Based on step S1 (through the interaction of the oxidant and complexing agent, Mn...), 3+ (It exists stably in solution), and can regulate the pH and reaction temperature during the precipitation process, thereby controlling the Mn content. 3+ 、Fe 3+ The precipitation efficiency of Mn 3+ 、Fe 3+ Uniform precipitation is achieved. pH and temperature affect the supersaturation of the solution in the reaction system. Supersaturation directly affects the nucleation and growth processes. High supersaturation promotes nucleation, while low supersaturation promotes growth. To achieve a loose interior and a dense shell, the reaction is controlled to prioritize nucleation in the early stages and growth in the later stages. Furthermore, the thickness of the inner core and outer shell can be controlled by adjusting the nucleation and growth times.

[0109] In a specific embodiment of the present invention, the volume ratio of mixed solution B-1 to mixed solution B-2 is (20~40):(80~60), and more preferably 40:60, 30:70, or 20:80.

[0110] In a preferred embodiment of the present invention, in step S3, the pH value of the mixed solution B-1 is adjusted to 3.0~5.0, more preferably 3.0, 3.5, 4.0, or 5.0.

[0111] In a preferred embodiment of the present invention, in step S3, the temperature is heated to 95~100°C.

[0112] In a preferred embodiment of the present invention, the heat preservation time in step S3 is 1~2 hours.

[0113] In a preferred embodiment of the present invention, in step S4, the pH value of the system is adjusted to 1.5 to 3.0, more preferably 1.5, 2.0, 2.7, or 3.0.

[0114] In a preferred embodiment of the present invention, in step S4, the temperature is maintained at 80~95℃, more preferably 80℃, 85℃, 90℃, or 95℃.

[0115] In a preferred embodiment of the present invention, the heat preservation time in step S4 is 0.5~2h.

[0116] In some embodiments of the present invention, in step S5, the drying temperature is 90~150℃, more preferably 90℃, 100℃, 120℃, or 150℃; the calcination temperature is 200~600℃, more preferably 450℃, 480℃, 500℃, or 550℃.

[0117] In a preferred embodiment of the present invention, stirring is carried out during steps S1, S3 and S4; more preferably, the stirring speed is 100~1000 rpm, and more preferably, the stirring speed is 350 rpm, 500 rpm, 800 rpm and 1000 rpm.

[0118] Secondly, this invention provides a manganese iron phosphate with the general chemical formula Mn. x Fe 1-x PO4, wherein 0.1≤x≤0.9, preferably 0.4≤x≤0.8, for example x is 0.5, 0.6, or 0.7; and manganese ferric phosphate is a secondary particle formed by the agglomeration of primary particles, and has a spherical or near-spherical structure; including a core and a shell, the core is loose and porous, and the shell is relatively compact.

[0119] The porous core of manganese iron phosphate material facilitates lithium diffusion into the material during the subsequent sintering process of the cathode material; the relatively compact outer shell helps to achieve a higher tap density, improves the crystal integrity of the sintered cathode material, and greatly reduces the dissolution rate of manganese iron in the cathode material.

[0120] In a preferred embodiment of the present invention, the diameter of the primary particles in the outer shell is 75-500 nm, for example 78 nm, 123 nm, 195 nm, 203 nm, 250 nm, or 470 nm; the diameter of the primary particles in the core is smaller than that in the outer shell. The difference in diameter between the primary particles in the core and the outer shell causes the prepared cathode material to spontaneously generate a gradation effect, increasing the compaction density of the cathode material.

[0121] In a preferred embodiment of the present invention, the ratio of the thickness of the outer shell to the radius of the core is 0.8 to 3.0:1, for example, it can be 0.84, 1.32, 1.42, 1.51, 1.68, or 2.70.

[0122] In a preferred embodiment of the present invention, the manganese iron phosphate satisfies at least one of the following conditions (a) to (c):

[0123] (a) The porosity of the core is 30-60%; preferably 40-50%;

[0124] (b) The porosity of the outer shell is 0.01~5%; preferably 0.05~2%;

[0125] (c) The porosity difference between the core and the shell is 25-60%; preferably 40-50%.

[0126] In a preferred embodiment of the present invention, the manganese iron phosphate satisfies at least one of the following conditions (d) to (f):

[0127] (d) The primary particles constituting the outer shell are dendritic or elongated;

[0128] (e) The average aspect ratio of the primary particles constituting the outer shell is 1.0 to 4.0, preferably 1.5 to 3.0;

[0129] (f) The particle size D50 of the secondary particles is 5.0~9.0μm.

[0130] To further explain, the average aspect ratio of a primary particle in this invention refers to the ratio of the length from the visible point at the root of the primary particle to the apex of the primary particle to the maximum width of the primary particle.

[0131] Based on the same inventive concept, the manganese iron phosphate provided by the present invention can be prepared by the aforementioned preparation method.

[0132] Furthermore, the present invention provides a positive electrode material prepared from the above-described manganese iron phosphate, and provides a battery comprising the positive electrode material.

[0133] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0134] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0135] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0136] In the specific embodiments and comparative examples, the main testing methods include:

[0137] XRD testing: Rigaku SmartLab SE intelligent X-ray diffractometer (Japan).

[0138] SEM test: Japanese Nippon Field scanning electron microscope.

[0139] EDS test: EDAX spectrometer.

[0140] Porosity: The analysis software used is Image J. The porosity is calculated as follows: Porosity = Pore area of ​​each region / Cross-sectional area of ​​each region × 100%.

[0141] Single particle size: Measured using NanoMeasurer software.

[0142] Example 1

[0143] (1) According to the chemical formula Mn 0.6 Fe 0.4 To prepare PO4, manganese sulfate and ferrous sulfate were added to a certain amount of pure water and stirred until the solution became clear and transparent. Then, phosphoric acid solution with an equimolar amount of manganese sulfate and ferrous sulfate was added and stirred thoroughly. Finally, an appropriate amount of pure water was added to make up the volume. The final solution A was a mixed solution with a manganese sulfate concentration of 0.9 mol / L, a ferrous sulfate concentration of 0.6 mol / L, and a phosphoric acid concentration of 1.5 mol / L.

[0144] (2) Add phosphoric acid as a complexing agent to mixed solution A according to the ratio of phosphate molar amount to total iron and manganese metal ion molar amount = 1.5:1, and stir thoroughly; then add ammonium persulfate as an oxidizing agent according to the ratio of oxidizing agent molar amount to total iron and manganese metal ion molar amount = 1.2:1, and continue stirring until the ammonium persulfate is completely dissolved. After filtering the resulting solution, let it stand for 12 hours to obtain mixed solution B.

[0145] (3) Using 40% volume of mixed solution B as the base liquid, ammonia water is added to the base liquid as a pH adjuster to adjust the pH of the base liquid to 4.0. After stirring thoroughly at a speed of 350 rpm, the temperature is raised to 95℃ and stirring is continued and kept warm for 1.5 h to obtain gray-green precursor slurry C.

[0146] (4) Using the gray-green precursor slurry C obtained in step (3) as the base liquid, under the conditions of stirring and heating, the remaining 60% volume of mixed solution B is slowly pumped in, and the pH of the system is adjusted to 2.0. During the reaction, the stirring speed is 350 rpm and the temperature is 85℃. After the feeding is completed, the temperature is kept for 1 hour to obtain the precursor slurry D.

[0147] (5) The product obtained in step S4 is centrifuged, dried and sieved to obtain powder, wherein the drying temperature is 120℃ and the drying time is 12h; the powder is calcined at 500℃ for 4h and then naturally cooled, and the calcination atmosphere is air to obtain manganese iron phosphate material.

[0148] Figure 1The image shows the XRD pattern of the manganese iron phosphate material obtained in Example 1. As can be seen from the image, the characteristic peak is pure phase MnPO4·H2O.

[0149] Figure 2 The EDS diagram of each element in the manganese iron phosphate material obtained in Example 1 shows that Mn, Fe, and P elements are evenly distributed.

[0150] Figure 3 The image shows a SEM image of the ferromanganese phosphate material obtained in Example 1. As can be seen from the image, the ferromanganese phosphate material is spherical or near-spherical. The diameter of the primary particles in the outer shell is 250 nm.

[0151] Figure 4 The image shows a cross-sectional SEM image of the ferromanganese phosphate material obtained in Example 1. As can be seen from the image, the ferromanganese phosphate material has a core-shell structure, with a loose core and a dense outer shell. Furthermore, the diameter of the primary particles in the core is significantly smaller than that in the outer shell. The ratio of the outer shell thickness to the core radius is 1.68. Further analysis revealed that the porosity of the core is 45.8%, and the primary particles constituting the outer shell are dendritic.

[0152] Comparative Example 1

[0153] The only difference between Comparative Example 1 and Example 1 is that the amount of complexing agent phosphoric acid added in step (2) is determined based on the molar amount of phosphoric acid: the total molar amount of iron and manganese metal ions = 0.8:1.

[0154] Figure 25 The image shows the XRD pattern of the manganese iron phosphate material obtained in Comparative Example 1. It can be seen from the figure that, in addition to MnPO4·H2O, the characteristic peaks also show the (NH4)Fe2(PO4)2OH(H2O)H2O phase.

[0155] Figure 26 The EDS diagrams of the elements in the manganese iron phosphate material obtained in Comparative Example 1 show that Mn, Fe, and P elements are evenly distributed.

[0156] Figure 27 The image shows the SEM image of the ferromanganese phosphate material obtained in Comparative Example 1. As can be seen from the image, the ferromanganese phosphate material exhibits a plate-like aggregate morphology, while also possessing a pyramidal morphology of basic ferric phosphate.

[0157] Figure 28 The image shows a cross-sectional SEM image of the manganese iron phosphate material obtained in Comparative Example 1. As can be seen from the image, the manganese iron phosphate material does not have a distinct core-shell structure.

[0158] Comparative Example 2

[0159] The only difference between Comparative Example 2 and Example 1 is that in step (2), the amount of ammonium persulfate added as an oxidant is determined based on the molar amount of ammonium persulfate: the total molar amount of manganese and iron = 0.8:1.

[0160] Figure 29 The image shows the XRD pattern of the manganese iron phosphate material obtained in Comparative Example 2. It can be seen from the figure that in addition to the characteristic peak of MnPO4·H2O, there is also a characteristic peak of Mn(H2PO4)2.

[0161] Figure 30 The EDS diagrams of the elements in the manganese iron phosphate material obtained in Comparative Example 2 show that Mn, Fe, and P elements are evenly distributed.

[0162] Figure 31 The image shows the SEM image of the ferromanganese phosphate material obtained in Comparative Example 2. As can be seen from the image, the ferromanganese phosphate material is spherical or near-spherical, but there are many disordered blocks on the surface.

[0163] Figure 32 The image shows a cross-sectional SEM image of the manganese iron phosphate material obtained in Comparative Example 2. The image reveals that the manganese iron phosphate material exhibits a core-shell structure, with a loose inner core and a dense outer shell. Further analysis shows that the porosity of the inner core is approximately 26.1%.

[0164] Comparative Example 3

[0165] The only difference between Comparative Example 3 and Example 1 is that in step (2), the amount of ammonium persulfate added is determined according to the molar amount of ammonium persulfate: the total molar amount of manganese and iron = 2:1.

[0166] Figure 33 The image shows the XRD pattern of the manganese iron phosphate material obtained in Comparative Example 3. As can be seen from the image, the characteristic peak of the product is pure phase MnPO4·H2O.

[0167] Figure 34 The EDS diagrams of various elements in the manganese iron phosphate material obtained in Comparative Example 3 show that Mn, Fe, and P elements are evenly distributed.

[0168] Figure 35 The image shows the SEM image of the ferromanganese phosphate material obtained in Comparative Example 3. As can be seen from the image, the ferromanganese phosphate material exhibits a blocky agglomerate morphology.

[0169] Figure 36 The image shows a cross-sectional SEM image of the manganese iron phosphate material obtained in Comparative Example 3. As can be seen from the image, the manganese iron phosphate material basically does not have the core-shell structure described above.

[0170] Comparative Example 4

[0171] The only difference between Comparative Example 4 and Example 1 is that the pH value of the substrate in step (3) is 5.5.

[0172] Figure 37 The image shows the XRD pattern of the manganese iron phosphate material obtained in Comparative Example 4. It can be seen from the figure that in addition to MnPO4·H2O, the product also has the characteristic peak of NH4MnPO4·H2O.

[0173] Figure 38 The EDS diagrams of the elements in the manganese iron phosphate material obtained in Comparative Example 4 show that Mn, Fe, and P elements are evenly distributed, and a certain amount of N element is also present, which is consistent with the XRD results.

[0174] Figure 39 The image shows the SEM image of the ferromanganese phosphate material obtained in Comparative Example 4. It can be seen from the image that the ferromanganese phosphate material exhibits obvious phase separation.

[0175] Figure 40 The image shows a cross-sectional SEM image of the manganese iron phosphate material obtained in Comparative Example 4. As can be seen from the image, the manganese iron phosphate material has no core-shell structure and no obvious pores inside.

[0176] Comparative Example 5

[0177] The only difference between Comparative Example 5 and Example 1 is that the pH value of the substrate in step (3) is 1.5.

[0178] Figure 41 The image shows the SEM image of the ferromanganese phosphate material obtained in Comparative Example 5. As can be seen from the image, the ferromanganese phosphate material has a blocky morphology and slight phase separation.

[0179] Comparative Example 6

[0180] The only difference between Comparative Example 6 and Example 1 is that the temperature in step (3) is 85°C.

[0181] Figure 42 The image shows the SEM image of the ferromanganese phosphate material obtained in Comparative Example 6. It can be seen from the image that the ferromanganese phosphate material exhibits obvious lamellar and dot-like phase separation.

[0182] Comparative Example 7

[0183] The only difference between Comparative Example 7 and Example 1 is that the temperature in step (3) is 105°C.

[0184] Figure 43 The image shows the SEM image of the ferromanganese phosphate material obtained in Comparative Example 7. As can be seen from the image, the ferromanganese phosphate material is an amorphous flocculent aggregate.

[0185] Comparative Example 8

[0186] The only difference between Comparative Example 8 and Example 1 is that the pH value in step (4) is 5.5.

[0187] Figure 44 The image shows a SEM image of the ferromanganese phosphate material obtained in Comparative Example 8. As can be seen from the image, the ferromanganese phosphate material has a flake-like morphology.

[0188] Comparative Example 9

[0189] The only difference between Comparative Example 9 and Example 1 is that the pH value in step (4) is 0.5.

[0190] Figure 45 The image shows a cross-sectional SEM image of the ferromanganese phosphate material obtained in Comparative Example 9. As can be seen from the image, the ferromanganese phosphate material is a solid sphere.

[0191] Comparative Example 10

[0192] The only difference between Comparative Example 10 and Example 1 is that the temperature in step (4) is 55°C.

[0193] Figure 46 The image shows a SEM image of the ferromanganese phosphate material obtained in Comparative Example 10. As can be seen from the image, the ferromanganese phosphate material exhibits spherical and flocculent phase separation.

[0194] Comparative Example 11

[0195] The only difference between Comparative Example 11 and Example 1 is that the temperature in step (4) is 105°C.

[0196] Figure 47 The image shows a SEM image of the ferromanganese phosphate material obtained in Comparative Example 11. As can be seen from the image, the ferromanganese phosphate material exhibits phase separation of lamellar and spherical shapes.

[0197] Example 2

[0198] (1) According to the chemical formula Mn 0.6 Fe 0.4 PO4 was prepared by adding manganese chloride and ferrous sulfate to a certain amount of pure water and stirring until the solution became clear and transparent. Then, an equimolar amount of ammonium dihydrogen phosphate was added and stirred thoroughly. Finally, an appropriate amount of pure water was added to make up the volume. The final solution A was a mixed solution with a manganese chloride concentration of 1.2 mol / L, a ferrous sulfate concentration of 0.8 mol / L, and an ammonium dihydrogen phosphate concentration of 2.0 mol / L.

[0199] (2) Add phosphoric acid as a complexing agent to mixed solution A according to the ratio of phosphate molar amount to total iron and manganese metal ion molar amount = 1.2:1, and stir thoroughly; then add ammonium nitrate as an oxidizing agent according to the ratio of oxidizing agent molar amount to total iron and manganese metal ion molar amount = 1.2:1, and continue stirring until the ammonium nitrate is completely dissolved. After filtering the resulting solution, let it stand for 12 hours to obtain mixed solution B.

[0200] (3) Using 30% volume of mixed solution B as the base liquid, ammonia water is added to the base liquid as a pH adjuster to adjust the pH of the base liquid to 3.0. After stirring evenly at a speed of 500 rpm, the temperature is raised to 95℃ and stirring is continued and kept warm for 1 hour to obtain gray-green precursor slurry C.

[0201] (4) Using the gray-green precursor slurry C obtained in step (3) as the base liquid, under the conditions of stirring and heating, the remaining 70% volume of mixed solution B is slowly pumped in, and the pH of the system is adjusted to 1.5. During the reaction, the stirring speed is 500 rpm and the temperature is 80℃. After the feeding is completed, the temperature is kept for 0.5 h to obtain the precursor slurry D.

[0202] (5) The product obtained in step S4 is centrifuged, dried and sieved to obtain powder, wherein the drying temperature is 120℃ and the drying time is 12h; the powder is calcined at 500℃ for 2h to dehydrate and then naturally cooled, and the calcination atmosphere is air to obtain manganese iron phosphate material.

[0203] Figure 5 The image shows the XRD pattern of the manganese iron phosphate material obtained in Example 2. As can be seen from the image, the characteristic peak is that of pure phase MnPO4·H2O.

[0204] Figure 6 The EDS diagram of each element in the manganese iron phosphate material obtained in Example 2 shows that Mn, Fe, and P elements are evenly distributed.

[0205] Figure 7 The image shows a SEM image of the ferromanganese phosphate material obtained in Example 2. As can be seen from the image, the ferromanganese phosphate material is spherical or near-spherical. The diameter of the primary particles in the outer shell is 195 nm.

[0206] Figure 8 The image shows a cross-sectional SEM image of the ferromanganese phosphate material obtained in Example 2. As can be seen from the image, the ferromanganese phosphate material has a core-shell structure, with a loose core and a dense outer shell. The ratio of the outer shell thickness to the core radius is 2.70. Further measurements revealed that the outer shell porosity is 0.31%, and the secondary particle size D50 is 8.41 μm.

[0207] Example 3

[0208] (1) According to the chemical formula Mn 0.5 Fe 0.5 To prepare PO4, manganese sulfate and ferrous sulfate are added to a certain amount of pure water and stirred until the solution is clear and transparent. Then, phosphoric acid solution with an equimolar amount of manganese sulfate and ferrous sulfate is added and stirred thoroughly. Finally, an appropriate amount of pure water is added to make up the volume. The final result is a mixed solution A with a manganese sulfate concentration of 0.5 mol / L, a ferrous sulfate concentration of 0.5 mol / L, and a phosphoric acid concentration of 1 mol / L.

[0209] (2) Add diammonium hydrogen phosphate as a complexing agent to mixed solution A according to the ratio of phosphate molar amount to total iron and manganese metal ion molar amount = 1.5:1, and stir thoroughly; then add ammonium persulfate as an oxidizing agent according to the ratio of oxidizing agent molar amount to total iron and manganese metal ion molar amount = 1.2:1, and continue stirring until the ammonium persulfate is completely dissolved. After filtering the resulting solution, let it stand for 12 hours to obtain mixed solution B.

[0210] (3) Using 20% ​​volume of mixed solution B as the base liquid, ammonia water is added to the base liquid as a pH adjuster to adjust the pH of the base liquid to 5.0. After stirring evenly at a speed of 800 rpm, the temperature is raised to 90℃ and stirring is continued and kept warm for 2 hours to obtain gray-green precursor slurry C.

[0211] (4) Using the gray-green precursor slurry C obtained in step (3) as the base liquid, under the conditions of stirring and heating, slowly pump in the remaining 80% volume of mixed solution B, and adjust the pH of the system to 3.0. During the reaction, the stirring speed is 800 rpm and the temperature is 95℃. After the feeding is completed, continue to keep warm for 2 hours to obtain the precursor slurry D.

[0212] (5) The product obtained in step S4 is centrifuged, dried and sieved to obtain powder, wherein the drying temperature is 120℃ and the drying time is 12h; the powder is calcined at 450℃ for 4h to dehydrate and then naturally cooled, and the calcination atmosphere is air to obtain manganese iron phosphate material.

[0213] Figure 9 The image shows the XRD pattern of the manganese iron phosphate material obtained in Example 3. As can be seen from the image, the characteristic peak is pure phase MnPO4·H2O.

[0214] Figure 10 The EDS diagram of each element in the manganese iron phosphate material obtained in Example 3 shows that Mn, Fe, and P elements are evenly distributed.

[0215] Figure 11 The image shows a SEM image of the ferromanganese phosphate material obtained in Example 3. As can be seen from the image, the ferromanganese phosphate material is spherical or near-spherical. The diameter of the primary particles in the outer shell is 78 nm.

[0216] Figure 12 The image shows a cross-sectional SEM image of the ferromanganese phosphate material obtained in Example 3. As can be seen from the image, the ferromanganese phosphate material has a core-shell structure, with a loose core and a dense outer shell. The ratio of the outer shell thickness to the core radius is 1.42. Further measurements show that the porosity difference between the core and shell is approximately 42%, and the particle size D50 of the secondary particles is 6.41 μm.

[0217] Example 4

[0218] (1) According to the chemical formula Mn 0.7Fe 0.3 PO4 was used to prepare a solution by adding manganese nitrate and ferrous nitrate to a certain amount of pure water and stirring until the solution was clear and transparent. Then, an equimolar amount of ammonium dihydrogen phosphate solution was added and stirred thoroughly. Finally, an appropriate amount of pure water was added to make up the volume. The final solution A was a mixed solution with a manganese nitrate concentration of 1.05 mol / L, a ferrous nitrate concentration of 0.45 mol / L, and a monoammonium phosphate concentration of 1.5 mol / L.

[0219] (2) Add phosphoric acid as a complexing agent to mixed solution A according to the ratio of phosphate molar amount to total iron and manganese metal ion molar amount = 1.2:1, and stir thoroughly; then add hydrogen peroxide as an oxidizing agent according to the ratio of oxidant molar amount to total iron and manganese metal ion molar amount = 1.2:1, filter the resulting solution and let it stand for 12 hours to obtain mixed solution B.

[0220] (3) Using 20% ​​volume of mixed solution B as the base liquid, ammonia water is added to the base liquid as a pH adjuster to adjust the pH of the base liquid to 3.0. After stirring evenly at a speed of 500 rpm, the temperature is raised to 95℃ and stirring is continued and kept warm for 1 hour to obtain gray-green precursor slurry C.

[0221] (4) Using the gray-green precursor slurry C obtained in step (3) as the base liquid, under the conditions of stirring and heating, slowly pump in the remaining 80% volume of mixed solution B, and adjust the pH of the system to 1.5. During the reaction, the stirring speed is 500 rpm and the temperature is 80℃. After the feeding is completed, continue to keep warm for 0.5h to obtain the precursor slurry D.

[0222] (5) The product obtained in step S4 is centrifuged, dried and sieved to obtain powder, wherein the drying temperature is 90℃ and the drying time is 15h; the powder is calcined at 450℃ for 4h and then naturally cooled, and the calcination atmosphere is air to obtain manganese iron phosphate material.

[0223] Figure 13 The image shows the XRD pattern of the manganese iron phosphate material obtained in Example 4. As can be seen from the image, the characteristic peak is that of pure phase MnPO4·H2O.

[0224] Figure 14 The EDS diagram of each element in the manganese iron phosphate material obtained in Example 4 shows that Mn, Fe, and P elements are evenly distributed.

[0225] Figure 15 The image shows a SEM image of the ferromanganese phosphate material obtained in Example 4. As can be seen from the image, the ferromanganese phosphate material is spherical or near-spherical. The diameter of the primary particles in the outer shell is 470 nm.

[0226] Figure 16The image shows a cross-sectional SEM image of the ferromanganese phosphate material obtained in Example 4. As can be seen from the image, the ferromanganese phosphate material has a core-shell structure, with a loose core and a dense outer shell. The ratio of the outer shell thickness to the core radius is 1.51. Further measurements revealed that the average aspect ratio of the primary outer shell particles is 2.41, and these particles are elongated.

[0227] Example 5

[0228] (1) According to the chemical formula Mn 0.6 Fe 0.4 PO4 was used to prepare a mixed solution. Manganese oxalate and ferrous oxalate were added to a certain amount of pure water and stirred until the solution became clear and transparent. Then, phosphoric acid solution with an equimolar amount of manganese oxalate and ferrous oxalate was added and stirred thoroughly. Finally, a suitable amount of pure water was added to bring the solution to volume. The final solution A consisted of 0.9 mol / L manganese oxalate, 0.6 mol / L ferrous oxalate, and 1.2 mol / L phosphoric acid.

[0229] (2) Add ammonium phosphate as a complexing agent to mixed solution A according to the ratio of phosphate molar amount to total iron and manganese metal ion molar amount = 2:1, and stir thoroughly; then add nitric acid as an oxidizing agent according to the ratio of oxidizing agent molar amount to total iron and manganese metal ion molar amount = 1.2:1, filter the resulting solution and let it stand for 12 hours to obtain mixed solution B.

[0230] (3) Using 40% volume of mixed solution B as the base liquid, ammonia water is added to the base liquid as a pH adjuster to adjust the pH of the base liquid to 5.0. After stirring thoroughly at a speed of 1000 rpm, the temperature is raised to 98℃ and stirring is continued and kept warm for 2 hours to obtain gray-green precursor slurry C.

[0231] (4) Using the gray-green precursor slurry C obtained in step (3) as the base liquid, under the conditions of stirring and heating, the remaining 60% volume of mixed solution B is slowly pumped in, and the pH of the system is adjusted to 3.0. During the reaction, the stirring speed is 1000 rpm and the temperature is 95℃. After the feeding is completed, the temperature is kept for 2 hours to obtain the precursor slurry D.

[0232] (5) The product obtained in step S4 is centrifuged, dried and sieved to obtain powder, wherein the drying temperature is 150℃ and the drying time is 12h; the powder is calcined at 550℃ for 2h to dehydrate and then naturally cooled, and the calcination atmosphere is air to obtain manganese iron phosphate material.

[0233] Figure 17 The image shows the XRD pattern of the manganese iron phosphate material obtained in Example 5. As can be seen from the image, the characteristic peak is that of pure phase MnPO4·H2O.

[0234] Figure 18The EDS diagram of each element in the manganese iron phosphate material obtained in Example 5 shows that Mn, Fe, and P elements are evenly distributed.

[0235] Figure 19 The image shows a SEM image of the ferromanganese phosphate material obtained in Example 5. As can be seen from the image, the ferromanganese phosphate material is spherical or near-spherical. The diameter of the primary particles in the outer shell is 203 nm.

[0236] Figure 20 The image shows a cross-sectional SEM image of the ferromanganese phosphate material obtained in Example 5. As can be seen from the image, the ferromanganese phosphate material has a core-shell structure, with a loose core and a dense outer shell. The ratio of the outer shell thickness to the core radius is 1.32. Further measurements revealed that the core porosity is 38.1%, and the secondary particle size D50 is 5.36 μm.

[0237] Example 6

[0238] (1) According to the chemical formula Mn 0.6 Fe 0.4 To prepare PO4, manganese acetate and ferrous acetate were added to a certain amount of pure water and stirred until the solution became clear and transparent. Then, phosphoric acid solution with an equimolar amount of manganese acetate and ferrous acetate was added and stirred thoroughly. Finally, an appropriate amount of pure water was added to make up the volume. The final solution A was a mixed solution with a manganese acetate concentration of 0.6 mol / L, a ferrous acetate concentration of 0.4 mol / L, and a phosphoric acid concentration of 1.0 mol / L.

[0239] (2) Add sodium pyrophosphate as a complexing agent to mixed solution A according to the ratio of pyrophosphate molar amount to total iron and manganese metal ion molar amount = 1.5:1, and stir thoroughly; then add ammonium persulfate as an oxidizing agent according to the ratio of oxidizing agent molar amount to total iron and manganese metal ion molar amount = 1.2:1, and continue stirring until the ammonium persulfate is completely dissolved. After filtering the resulting solution, let it stand for 12 hours to obtain mixed solution B.

[0240] (3) Using 30% volume of mixed solution B as the base liquid, ammonia water is added to the base liquid as a pH adjuster to adjust the pH of the base liquid to 3.5. After stirring thoroughly at a speed of 500 rpm, the temperature is raised to 95℃ and stirring is continued and kept warm for 1.5 h to obtain gray-green precursor slurry C.

[0241] (4) Using the gray-green precursor slurry C obtained in step (3) as the base liquid, under the conditions of stirring and heating, the remaining 70% volume of mixed solution B is slowly pumped in, and the pH of the system is adjusted to 2.7. During the reaction, the stirring speed is 800 rpm and the temperature is 90℃. After the feeding is completed, the temperature is kept for 2 hours to obtain the precursor slurry D.

[0242] (5) The product obtained in step S4 is centrifuged, dried and sieved to obtain powder, wherein the drying temperature is 100℃ and the drying time is 15h; the powder is calcined at 480℃ for 4h and then naturally cooled, and the calcination atmosphere is air to obtain manganese iron phosphate material.

[0243] Figure 21 The image shows the XRD pattern of the manganese iron phosphate material obtained in Example 6. As can be seen from the image, the characteristic peak is that of pure phase MnPO4·H2O.

[0244] Figure 22 The EDS diagram of each element in the manganese iron phosphate material obtained in Example 6 shows that Mn, Fe, and P elements are evenly distributed.

[0245] Figure 23 The image shows a SEM image of the ferromanganese phosphate material obtained in Example 6. As can be seen from the image, the ferromanganese phosphate material is spherical or near-spherical. The diameter of the primary particles in the outer shell is 123 nm.

[0246] Figure 24 The image shows a cross-sectional SEM image of the ferromanganese phosphate material obtained in Example 6. As can be seen from the image, the ferromanganese phosphate material has a core-shell structure, with a loose core and a dense outer shell. The ratio of the outer shell thickness to the core radius is 0.84. Further measurement showed that the porosity difference between the core and the outer shell was 42%, and the primary particles in the outer shell were strip-shaped.

[0247] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing ferric manganese phosphate, characterized in that, include: Step S1: Add a complexing agent and an oxidizing agent to a mixed solution A containing manganese, iron, and phosphorus sources to obtain a mixed solution B; the molar ratio of the complexing agent to the total molar ratio of iron and manganese is 1~2:1; the molar ratio of the oxidizing agent to the total molar ratio of iron and manganese is 1~1.5:

1. Step S2: Divide the mixed solution B into two parts: mixed solution B-1 and mixed solution B-2; Step S3: Adjust the pH of mixed solution B-1 to 2.0~5.0, heat to 90~100℃, keep warm, and obtain slurry I; Step S4: Add mixed solution B-2 to slurry I, adjust the pH of the system to 1~5, and keep it at 60~100℃ to obtain slurry II; Step S5: The slurry II is subjected to solid-liquid separation, dried, sieved, and calcined to obtain manganese iron phosphate.

2. The method for preparing ferric manganese phosphate as described in claim 1, characterized in that, The total molar concentration of manganese and iron in the mixed solution A is 0.2~2.0 mol / L.

3. The method for preparing ferric manganese phosphate as described in claim 1 or 2, characterized in that, The molar ratio of manganese to iron in the mixed solution A is 1~2:

1.

4. The method for preparing manganese iron phosphate as described in claim 1, characterized in that, The volume ratio of mixed solution B-1 to mixed solution B-2 is (20~40):(80~60).

5. The method for preparing ferric manganese phosphate as described in claim 1, characterized in that, In step S3, the pH of the mixed solution B-1 is adjusted to 3.0~5.

0.

6. The method for preparing manganese iron phosphate as described in claim 1, characterized in that, In step S3, heat to 95~100℃.

7. The method for preparing ferric manganese phosphate as described in claim 1, characterized in that, In step S3, the heat preservation time is 1~2 hours.

8. The method for preparing ferric manganese phosphate as described in claim 1, characterized in that, In step S4, the pH of the system is adjusted to 1.5~3.

0.

9. The method for preparing ferric manganese phosphate as described in claim 1, characterized in that, In step S4, the temperature is maintained at 80~95℃.

10. The method for preparing ferric manganese phosphate as described in claim 9, characterized in that, In step S4, the heat preservation time is 0.5~2h.

11. The method for preparing ferric manganese phosphate as described in claim 1, characterized in that, Stirring is carried out during steps S1, S3, and S4; the stirring speed is 100~1000 rpm.

12. The method for preparing ferric manganese phosphate as described in claim 1, characterized in that, In step S5, the drying temperature is 90~150℃.

13. The method for preparing ferric manganese phosphate as described in claim 1, characterized in that, In step S5, the calcination temperature is 200~600℃.

14. A type of manganese iron phosphate, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 13.

15. The manganese iron phosphate as described in claim 14, characterized in that, The chemical formula of the manganese iron phosphate is Mn. x Fe 1- x PO4, wherein 0.1≤x≤0.9; the manganese iron phosphate is a secondary particle formed by the agglomeration of primary particles, and has a spherical or near-spherical structure; it includes a core and a shell, the core being loose and porous, and the shell being relatively compact.

16. The ferric manganese phosphate as described in claim 15, characterized in that, 0.4≤x≤0.8。 17. The ferric manganese phosphate according to any one of claims 15-16, characterized in that, The diameter of the primary particles in the outer shell is 100~500nm; the diameter of the primary particles in the core is smaller than that of the primary particles in the outer shell.

18. The ferromanganese phosphate as described in claim 15 or 16, characterized in that, The ratio of the thickness of the outer shell to the radius of the core is 0.8 to 3.0:

1.

19. The ferromanganese phosphate as described in claim 15 or 16, characterized in that, The manganese iron phosphate satisfies at least one of the following conditions (a) to (c): (a) The porosity of the core is 30-60%; (b) The porosity of the outer shell is 0.01~5%; (c) The porosity difference between the core and the shell is 25-60%; And / or, the manganese iron phosphate satisfies at least one of the following conditions (d) to (f): (d) The primary particles constituting the outer shell are dendritic or elongated; (e) The average aspect ratio of the primary particles constituting the outer shell is 1.0 to 4.0; (f) The particle size D50 of the secondary particles is 5.0~9.0μm.

20. A positive electrode material, characterized in that, Ferric manganese phosphate prepared by any one of the preparation methods according to claims 1-13 or 14-19.

21. A battery, characterized in that, Includes the cathode material as described in claim 20.

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