Ferromanganese phosphate precursor as well as preparation method and application thereof

Abstract

The invention relates to a ferromanganese phosphate precursor and a preparation method and application thereof, and relates to the technical field of new materials. The preparation method comprises the following steps: respectively preparing an iron source solution, a manganese source solution and a phosphorus source solution from an iron source, a manganese source and a phosphorus source, adding an oxidant into the manganese source solution, carrying out an oxidation reaction, adding the iron source solution, mixing, and carrying out first pH value adjustment to obtain a mixed material solution; adding a phosphorus source solution and a dispersing agent into the mixed material liquid, carrying out secondary pH value adjustment, stirring, carrying out high-pressure hydrothermal synthesis, carrying out suction filtration, drying and calcining to obtain a ferromanganese phosphate precursor; according to the preparation method, coprecipitation of ferromanganese phosphate is regulated and controlled by adjusting the pH value twice, uniform mixing and distribution of manganese and iron elements on the atomic level are promoted, and the uniformity of the manganese and iron elements in the lithium ferromanganese phosphate-based material is improved. The method is simple and low in cost, and the obtained precursor has high purity and good consistency, so that the electrochemical performance of the positive electrode material is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of new materials, and in particular to a ferromanganese phosphate precursor and a preparation method and application thereof. Background Art

[0002] With the advancement of new energy technologies, the market demand for lithium-ion batteries with high energy density, high safety performance and high economy is increasing. As an emerging lithium-ion battery positive electrode material, lithium iron manganese phosphate combines the advantages of lithium iron phosphate and lithium manganese phosphate, showing high safety, stability, excellent working voltage and theoretical energy density. Lithium iron manganese phosphate is regarded as an advanced version of lithium iron phosphate, so it is very popular in the field of lithium batteries. However, the traditional preparation method of lithium manganese iron phosphate has many defects. For example, when preparing the battery positive electrode material by the co-precipitation method, it is difficult to effectively remove impurities introduced in the raw materials during the co-precipitation and washing steps, resulting in a decrease in the purity of the final product, which in turn affects the battery performance; Mn 2+ Not easily oxidized to Mn 3+ , which will also affect the purity of the final product; the defects in the crystal structure increase the difficulty of sintering; the ratio of transition metals to phosphate is difficult to control within the required range; harmful waste liquid may be generated during the preparation process, increasing the cost of wastewater treatment. The preparation method of traditional manganese ferrophosphate precursor has problems such as complex process, high cost and poor product consistency.

[0003] In response to the above problems, some researchers proposed to prepare the ferromanganese phosphate precursor by co-precipitation method, adding phosphoric acid to the manganese source and iron source respectively and then oxidizing the metal to +3 valence. However, the finished product has low purity, uneven mixing of manganese and iron, wide particle size distribution, high equipment requirements, and is not conducive to large-scale production. Some people also proposed to add the metal liquid to the organic solution separately, and precipitate the ferromanganese phosphate in the phosphorus source solution containing a large amount of organic solution. However, such operation requires the use of a large amount of organic solvent, which is costly and may bring certain environmental risks.

[0004] Therefore, in view of the shortcomings of existing technologies and market demand, it is particularly important to develop an efficient, environmentally friendly and cost-effective method for preparing manganese-rich ferromanganese phosphate precursors, which can not only promote the development of high-energy-density lithium batteries, but also promote the widespread application of new energy technologies. Summary of the invention

[0005] In view of the above problems, the present invention provides a method for preparing a ferromanganese phosphate precursor, which regulates the coprecipitation of ferromanganese phosphate by adjusting the pH value twice, thereby promoting the uniform mixing and distribution of manganese and iron elements at the atomic level, and improving the uniformity of manganese and iron elements in the lithium ferromanganese phosphate-based material. The method is simple and low in cost, and the obtained precursor has high purity and good consistency, thereby improving the electrochemical performance of the positive electrode material.

[0006] In order to achieve the above object, the present invention provides a method for preparing a ferromanganese phosphate precursor, comprising the following steps:

[0007] Redox reaction: preparing an iron source, a manganese source and a phosphorus source into an iron source solution, a manganese source solution and a phosphorus source solution respectively, adding an oxidant into the manganese source solution, performing an oxidation reaction, adding the iron source solution, mixing, and first adjusting the pH value to obtain a mixed liquid;

[0008] Preparation of ferromanganese phosphate precursor: adding the mixed liquid to a phosphorus source solution and a dispersant, performing a second pH adjustment, stirring, performing high-pressure hydrothermal synthesis, filtering, drying, and calcining to obtain the ferromanganese phosphate precursor.

[0009] In order to solve the problem of uneven mixing of manganese and iron and non-uniform particle size in the prior art, but not relying on the introduction of a large amount of organic solvents, the inventors propose the above-mentioned preparation method, by first adjusting the pH value to regulate the process of the redox reaction, control the oxidation state of manganese and iron, and ensure that the redox reaction step can generate the target product. Specifically, according to the Eh-pH diagram of the Mn-P-H2O system at 25°C, at a potential of -0.5V to 0.5V, when the pH value is greater than 3, a phosphate precipitation of divalent manganese can be generated, that is, if the pH value is too high, it is easy to cause manganese to be not completely oxidized to +3 valence due to the generation of divalent manganese phosphate, and then the target product cannot be generated. At the same time, the formation and characteristics of the ferromanganese phosphate precipitation (including but not limited to the particle size, distribution, purity, etc. of the precipitation) are regulated by the second pH value. During the research process, the inventors also tried to prepare the ferromanganese phosphate precursor by adjusting the pH value once. However, since the higher the temperature of the hydrothermal synthesis reaction, the wider the range of divalent manganese phosphate generation, adjusting the pH once will lead to the generation of too much divalent manganese phosphate; if all the reactants are mixed and the pH is adjusted at one time, Mn 2+ Cannot be completely oxidized to Mn 3+ , which leads to the problems of difficult to control manganese ratio, poor stability and uniformity of lithium manganese phosphate samples. The present invention adjusts the pH value twice to convert divalent manganese ions into trivalent manganese ions, and solves the problems of poor stability and uniformity of the precursor of manganese phosphate through a simple process flow. The preparation process is as follows: Figure 1 At the same time, in the step of preparing the ferromanganese phosphate precursor, a high-pressure hydrothermal synthesis method is used, the sample is mixed more evenly, the reaction rate is faster, and the reaction is more complete.

[0010] In one embodiment, in the redox reaction step, the molar ratio of the iron source, manganese source and phosphorus source is (0.2-0.4):(0.6-1.0):(1.0-2.5); the molar ratio of the manganese source to the oxidant is 1:(1.2-5); and the first pH value is adjusted to (-2.5)-2.5.

[0011] In one embodiment, the sum of the amounts of iron ions in the iron source and manganese ions in the manganese source: the amount of phosphate in the phosphorus source is 1:(1.0-2.5).

[0012] In one embodiment, in the step of preparing the ferromanganese phosphate precursor, the ratio of the molar amount of the dispersant to the sum of the molar amounts of the manganese source and the iron source is 1:(5-20); the second step is to adjust the pH value to 2.5-7.5.

[0013] According to the comparison of the Eh-pH diagrams of the Mn-P-H2O system at different temperatures, it can be seen that the higher the temperature, the narrower the region where divalent manganese exists stably. Therefore, under the premise of the aforementioned high-pressure hydrothermal synthesis reaction, after divalent manganese is oxidized to trivalent manganese, trivalent manganese precipitation can be formed at a lower pH.

[0014] In one embodiment, the iron source includes at least one of ferric nitrate, ferric nitrate hydrate, ferric sulfate, ferric sulfate hydrate, ferric chloride, ferric chloride hydrate, ferric acetate, ferric acetate hydrate, ferric oxalate, and ferric oxalate hydrate;

[0015] The manganese source includes at least one of manganese nitrate, manganese chloride, manganese sulfate, manganese acetate, and manganese oxalate;

[0016] The phosphorus source includes at least one of phosphoric acid, diammonium hydrogen phosphate, and ammonium dihydrogen phosphate;

[0017] The oxidant includes at least one of hydrogen peroxide and nitric acid;

[0018] The dispersant includes at least one of ethylene glycol, ethanol, polyvinyl alcohol, methyl pentanol, and n-butanol.

[0019] In one of the embodiments, in the step of preparing the ferromanganese phosphate precursor, the reaction conditions of the high-pressure hydrothermal synthesis include: a temperature of 100-260° C., a stirring speed of 200-600 r / min, and a stirring time of 6-20 h.

[0020] In one embodiment, in the step of preparing the ferromanganese phosphate precursor, the second pH adjustment is performed and then stirred for 1-3 hours.

[0021] In one of the embodiments, in the step of preparing the ferromanganese phosphate precursor, the drying temperature is ≤80°C; the calcination temperature is 400-700°C, and the calcination time is 2-4h.

[0022] In one embodiment, the calcination atmosphere is air atmosphere.

[0023] In one embodiment, the oxidation-reduction reaction step and the step of preparing the ferromanganese phosphate precursor use alkaline solution for the first pH adjustment and the second pH adjustment.

[0024] In one of the embodiments, in the redox reaction step, ammonia water is used for the first pH adjustment; in the step of preparing the ferromanganese phosphate precursor, ammonia water and / or sodium hydroxide is used for the second pH adjustment.

[0025] In one embodiment, the temperature of the oxidation reaction is 20-50°C.

[0026] The present invention also provides a ferromanganese phosphate precursor obtained by the preparation method.

[0027] In one embodiment, the chemical formula of the ferromanganese phosphate precursor is Mn x Fe 1-x PO4(0.6≤x<1).

[0028] The present invention also provides a battery positive electrode material, which is prepared by using the ferromanganese phosphate precursor.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] A ferromanganese phosphate precursor and a preparation method and application thereof of the present invention, wherein the preparation method regulates the coprecipitation of ferromanganese phosphate by adjusting the pH value twice, thereby promoting the uniform mixing and distribution of manganese and iron elements at the atomic level, and improving the uniformity of manganese and iron elements in the lithium ferromanganese phosphate-based material. The method is simple and low in cost, and the obtained precursor has high purity and good consistency, thereby improving the electrochemical performance of the positive electrode material. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a preparation flow chart of the present invention;

[0032] Figure 2 This is a SEM image of the ferromanganese phosphate precursor obtained in Example 1;

[0033] Figure 3 This is the XRD pattern of the ferromanganese phosphate precursor obtained in Example 1;

[0034] Figure 4 This is a SEM image of the ferromanganese phosphate precursor obtained in Comparative Example 1;

[0035] Figure 5 This is the SEM image of the ferromanganese phosphate precursor prepared in Comparative Example 2. DETAILED DESCRIPTION

[0036] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0038] source:

[0039] Unless otherwise specified, the reagents, materials, and equipment used in this example are all commercially available; the experimental methods are all conventional experimental methods in the art unless otherwise specified.

[0040] Example 1

[0041] A method for preparing a ferromanganese phosphate precursor.

[0042] 1. Redox reaction.

[0043] 122 g of ferric chloride (iron source), 142 g of manganese chloride (manganese source) and 330 g of diammonium phosphate (phosphorus source) were weighed and dissolved in deionized water to prepare a solution. In this embodiment, the molar amounts of the iron source, manganese source and phosphorus source were 0.7521 mol, 1.1284 mol and 2.4989 mol respectively.

[0044] Add 150 ml of hydrogen peroxide (oxidant) to the manganese chloride solution (manganese source solution) to make the molar ratio of manganese source to oxidant 1: (1.2-5). After sufficient oxidation, add ferric chloride solution (iron source solution) and mix evenly. Adjust the pH value of the solution to 0.2.

[0045] 2. Prepare ferromanganese phosphate precursor.

[0046] Slowly drop diammonium hydrogen phosphate solution (phosphorus source solution) into the iron-manganese mixed solution, and drop 25 ml of ethylene glycol (dispersant) to make the ratio of the molar amount of the dispersant to the sum of the molar amounts of the manganese source and the iron source be 1: (5-20). After the dropwise addition is completed, adjust the solution pH to 4.5 and keep stirring to cause a coprecipitation reaction;

[0047] The solution was further transferred to a polytetrafluoroethylene liner, placed in a high-pressure reactor, heated to 130° C., stirred at a speed of 200-600 r / min, and reacted for 12 h.

[0048] The product obtained by the reaction was filtered and placed in a constant temperature drying oven at 75° C. for drying. The dried solid was calcined at 570° C. for 2 h in a synthetic air atmosphere to obtain a ferromanganese phosphate precursor.

[0049] The SEM image of the ferromanganese phosphate precursor prepared in this example is as follows Figure 2 As shown, the XRD pattern is Figure 3 shown.

[0050] Example 2

[0051] A method for preparing a ferromanganese phosphate precursor.

[0052] 1. Redox reaction.

[0053] 104 g of ferric chloride (iron source), 137 g of manganese oxalate (manganese source) and 408 g of diammonium phosphate (phosphorus source) were weighed and dissolved in deionized water to prepare a solution. In this embodiment, the molar amounts of the iron source, manganese source and phosphorus source were 0.6412 mol, 1.0887 mol and 3.0896 mol respectively.

[0054] Add 130 ml of hydrogen peroxide (oxidant) to the manganese oxalate solution (manganese source solution) to make the molar ratio of manganese source to oxidant 1: (1.2-5). After sufficient oxidation, add ferric chloride solution (iron source solution) and mix evenly. Adjust the pH value of the solution to 0.

[0055] 2. Prepare ferromanganese phosphate precursor.

[0056] Slowly drop diammonium hydrogen phosphate solution (phosphorus source solution) into the iron-manganese mixed solution, and drop 30 ml of ethylene glycol (dispersant) to make the ratio of the molar amount of the dispersant to the sum of the molar amounts of the manganese source and the iron source be 1: (5-20). After the dropwise addition is completed, adjust the pH value of the solution to 6 and keep stirring to cause a coprecipitation reaction;

[0057] The solution was further transferred to a polytetrafluoroethylene liner, placed in a high-pressure reactor, heated to 140° C., stirred at a speed of 200-600 r / min, and reacted for 12 h.

[0058] The product obtained by the reaction was filtered and placed in a constant temperature drying oven at 75° C. for drying. The dried solid was calcined at 550° C. for 2.5 h in a synthetic air atmosphere to obtain a ferromanganese phosphate precursor.

[0059] Example 3

[0060] A method for preparing a ferromanganese phosphate precursor.

[0061] 1. Redox reaction.

[0062] 98 g of ferric chloride (iron source), 177 g of manganese chloride (manganese source) and 347 g of diammonium phosphate (phosphorus source) were weighed and dissolved in deionized water to prepare a solution. In this embodiment, the molar amounts of the iron source, manganese source and phosphorus source were 0.6042 mol, 1.4065 mol and 2.6277 mol respectively.

[0063] Add 250 ml of hydrogen peroxide (oxidant) to the manganese chloride solution (manganese source solution) to make the molar ratio of manganese source to oxidant 1: (1.2-5). After sufficient oxidation, add ferric chloride solution (iron source solution) and mix evenly. Adjust the pH value of the solution to 0.5.

[0064] 2. Prepare ferromanganese phosphate precursor.

[0065] Slowly drop diammonium hydrogen phosphate solution (phosphorus source solution) into the iron-manganese mixed solution, and drop 30 ml of ethylene glycol (dispersant) to make the ratio of the molar amount of the dispersant to the sum of the molar amounts of the manganese source and the iron source be 1: (5-20). After the dropwise addition is completed, adjust the pH value of the solution to 4.5 and keep stirring to cause a coprecipitation reaction;

[0066] The solution was further transferred to a polytetrafluoroethylene liner, placed in a high-pressure reactor, heated to 130° C., stirred at a speed of 200-600 r / min, and reacted for 10 hours.

[0067] The product obtained by the reaction was filtered and placed in a constant temperature drying oven at 75° C. for drying. The dried solid was calcined at 550° C. for 2 h in a synthetic air atmosphere to obtain a ferromanganese phosphate precursor.

[0068] Example 4

[0069] A method for preparing a ferromanganese phosphate precursor.

[0070] 1. Redox reaction.

[0071] 112 g of ferric chloride (iron source), 230 g of manganese oxalate (manganese source) and 450 g of diammonium phosphate (phosphorus source) were weighed and dissolved in deionized water to prepare a solution. In this embodiment, the molar amounts of the iron source, manganese source and phosphorus source were 0.6905 mol, 1.8277 mol and 3.4076 mol respectively.

[0072] Add 220 ml of hydrogen peroxide (oxidant) to the manganese oxalate solution (manganese source solution) to make the molar ratio of manganese source to oxidant 1: (1.2-5). After sufficient oxidation, add ferric chloride solution (iron source solution) and mix evenly. Adjust the pH value of the solution to -0.5.

[0073] 2. Prepare ferromanganese phosphate precursor.

[0074] Slowly drop diammonium phosphate solution (phosphorus source solution) into the iron-manganese mixed solution, and drop 48 ml of ethylene glycol (dispersant) to make the ratio of the molar amount of the dispersant to the sum of the molar amounts of the manganese source and the iron source be 1: (5-20). After the dropwise addition is completed, adjust the pH value of the solution to 5 and keep stirring to cause a coprecipitation reaction;

[0075] The solution was further transferred to a polytetrafluoroethylene liner, placed in a high-pressure reactor, heated to 100° C., stirred at a speed of 200-600 r / min, and reacted for 13 h.

[0076] The product obtained by the reaction was filtered and placed in a constant temperature drying oven at 75° C. for drying. The dried solid was calcined at 550° C. for 2.5 h in a synthetic air atmosphere to obtain a ferromanganese phosphate precursor.

[0077] Example 5

[0078] A method for preparing a ferromanganese phosphate precursor.

[0079] 1. Redox reaction.

[0080] 104 g of ferric chloride (iron source), 323 g of manganese chloride (manganese source) and 500 g of diammonium phosphate (phosphorus source) were weighed and dissolved in deionized water to prepare a solution. In this embodiment, the molar amounts of the iron source, manganese source and phosphorus source were 0.6412 mol, 2.5668 mol and 3.7863 mol respectively.

[0081] Add 350 ml of hydrogen peroxide (oxidant) to the manganese chloride solution (manganese source solution) to make the molar ratio of manganese source to oxidant 1: (1.2-5). After sufficient oxidation, add ferric chloride solution (iron source solution) and mix evenly. Adjust the pH value of the solution to -0.2.

[0082] 2. Prepare ferromanganese phosphate precursor.

[0083] Slowly drop diammonium phosphate solution (phosphorus source solution) into the iron-manganese mixed solution, and drop 56 ml of ethylene glycol (dispersant) to make the ratio of the molar amount of the dispersant to the sum of the molar amounts of the manganese source and the iron source be 1: (5-20). After the dropwise addition is completed, adjust the pH value of the solution to about 4 and keep stirring to cause a coprecipitation reaction;

[0084] The solution was further transferred to a polytetrafluoroethylene liner, placed in a high-pressure reactor, heated to 110° C., stirred at a speed of 200-600 r / min, and reacted for 11 hours.

[0085] The product obtained by the reaction was filtered and placed in a constant temperature drying oven at 75° C. for drying. The dried solid was calcined at 550° C. for 3 h in a synthetic air atmosphere to obtain a ferromanganese phosphate precursor.

[0086] Example 6

[0087] A method for preparing a ferromanganese phosphate precursor.

[0088] 1. Redox reaction.

[0089] 116 g of ferric chloride (iron source), 412 g of manganese oxalate (manganese source) and 536 g of diammonium phosphate (phosphorus source) were weighed and dissolved in deionized water to prepare a solution. In this embodiment, the molar amounts of the iron source, manganese source and phosphorus source were 0.7151 mol, 3.2740 mol and 4.0589 mol respectively.

[0090] Add 400 ml of hydrogen peroxide (oxidant) to the manganese chloride solution (manganese source solution) to make the molar ratio of manganese source to oxidant 1: (1.2-5). After sufficient oxidation, add ferric chloride solution (iron source solution) and mix evenly. Adjust the pH value of the solution to -0.8.

[0091] 2. Prepare ferromanganese phosphate precursor.

[0092] Slowly drop diammonium phosphate solution (phosphorus source solution) into the iron-manganese mixed solution, and drop 54 ml of ethylene glycol (dispersant) to make the ratio of the molar amount of the dispersant to the sum of the molar amounts of the manganese source and the iron source be 1: (5-20). After the dropwise addition is completed, adjust the solution pH to 6 and keep stirring to cause a coprecipitation reaction;

[0093] The solution was further transferred to a polytetrafluoroethylene liner, placed in a high-pressure reactor, heated to 120° C., stirred at a speed of 200-600 r / min, and reacted for 10 hours.

[0094] The product obtained by the reaction was filtered and then placed in a constant temperature drying oven at 75° C. for drying; the dried solid was calcined at 600° C. for 2 h in a synthetic air atmosphere to obtain a ferromanganese phosphate precursor.

[0095] Comparative Example 1

[0096] A method for preparing a ferromanganese phosphate precursor.

[0097] Step 1: Weigh 52 g of ferric chloride (iron source), 161 g of manganese chloride (manganese source) and 250 g of diammonium phosphate (phosphorus source) respectively, and dissolve them in deionized water to prepare a solution.

[0098] Step 2: Add 175 ml of hydrogen peroxide (oxidant) to the manganese chloride solution (manganese source solution), add ferric chloride solution (iron source solution) and mix, slowly drop diammonium phosphate solution (phosphorus source solution) into the iron-manganese mixed solution, drop 28 ml of ethylene glycol (dispersant), adjust the pH value of the solution to about 4.5 after the dropwise addition is completed, and stir to cause a coprecipitation reaction;

[0099] Step 3: further transfer the solution to a polytetrafluoroethylene liner, place it in a high-pressure reactor, heat it to 110°C, stir it at a speed of 200-600 r / min, and react for 10 hours.

[0100] Step 4: Filter the product obtained from the reaction, and after filtration, place it in a constant temperature drying oven at 75° C. for drying; calcine the dried solid at 550° C. for 3 hours in a synthetic air atmosphere to obtain a manganese iron phosphate precursor.

[0101] In this comparative example, the pH value of the solution was adjusted only once, and the SEM image of the product was as follows: Figure 4 As shown, the particle sizes are different and the purity of the finished product is low.

[0102] Comparative Example 2

[0103] A method for preparing a ferromanganese phosphate precursor.

[0104] Step 1: Weigh 49 g of ferric chloride (iron source), 89 g of manganese chloride (manganese source) and 174 g of diammonium hydrogen phosphate (phosphorus source) respectively, and dissolve them in deionized water to prepare a solution.

[0105] Step 2: Add 125 ml of hydrogen peroxide (oxidant) to the manganese chloride solution (manganese source solution), add ferric chloride solution and mix evenly after sufficient oxidation, and adjust the pH value of the solution to 4.

[0106] Step 3: Further slowly add diammonium hydrogen phosphate solution (phosphorus source solution) to the iron-manganese mixed solution, add 15 ml of ethylene glycol (dispersant), adjust the pH value of the solution to 6 after the addition is completed, and stir continuously to cause a coprecipitation reaction;

[0107] Step 4: further transfer the solution to a polytetrafluoroethylene liner, place it in a high pressure reactor, heat it to 130°C, stir it at a speed of 200-600 r / min, and react for 11 hours.

[0108] Step 5: Filter the product obtained from the reaction, and place it in a constant temperature drying oven at 75° C. for drying; calcine the dried solid at 550° C. for 2 hours in a synthetic air atmosphere to obtain a manganese iron phosphate precursor.

[0109] In this comparative example, the pH value was adjusted to 4 for the first time and to 6.5 for the second time. The SEM image of the obtained product is as follows: Figure 5 As shown, the product morphology is also not good, the particles are uneven and of different sizes.

[0110] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0111] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a ferromanganese phosphate precursor, characterized in that: The following steps are involved: Redox reaction: preparing an iron source, a manganese source and a phosphorus source into an iron source solution, a manganese source solution and a phosphorus source solution respectively, adding an oxidant into the manganese source solution, performing an oxidation reaction, adding the iron source solution, mixing, and first adjusting the pH value to obtain a mixed liquid; Preparation of ferromanganese phosphate precursor: adding the mixed liquid to a phosphorus source solution and a dispersant, performing a second pH adjustment, stirring, performing high-pressure hydrothermal synthesis, filtering, drying, and calcining to obtain the ferromanganese phosphate precursor.

2. The preparation method according to claim 1, characterized in that: In the redox reaction step, the molar ratio of the iron source, manganese source and phosphorus source is (0.2-0.4):(0.6-1.0):(1.0-2.5); the molar ratio of the manganese source to the oxidant is 1:(1.2-5); the first pH value is adjusted to (-2.5)-2.

5.

3. The preparation method according to claim 2, characterized in that: The sum of the amounts of iron ions in the iron source and manganese ions in the manganese source: the amount of phosphate in the phosphorus source is 1:(1.0-2.5).

4. The preparation method according to claim 1, characterized in that: In the step of preparing the ferromanganese phosphate precursor, the ratio of the molar amount of the dispersant to the sum of the molar amounts of the manganese source and the iron source is 1:(5-20); the second step is to adjust the pH value to 2.5-7.

5.

5. The preparation method according to claim 1, characterized in that: The iron source includes at least one of ferric nitrate, ferric nitrate hydrate, ferric sulfate, ferric sulfate hydrate, ferric chloride, ferric chloride hydrate, ferric acetate, ferric acetate hydrate, ferric oxalate, and ferric oxalate hydrate; The manganese source includes at least one of manganese nitrate, manganese chloride, manganese sulfate, manganese acetate, and manganese oxalate; The phosphorus source includes at least one of phosphoric acid, diammonium hydrogen phosphate, and ammonium dihydrogen phosphate; The oxidant includes at least one of hydrogen peroxide and nitric acid; The dispersant includes at least one of ethylene glycol, ethanol, polyvinyl alcohol, methyl pentanol, and n-butanol.

6. The preparation method according to claim 1, characterized in that: In the step of preparing the ferromanganese phosphate precursor, the reaction conditions of the high-pressure hydrothermal synthesis include: a temperature of 100-260° C., a stirring speed of 200-600 r / min, and a stirring time of 6-20 h.

7. The preparation method according to claim 1, characterized in that: In the step of preparing the ferromanganese phosphate precursor, the drying temperature is ≤80°C; the calcination temperature is 400-700°C, and the calcination time is 2-4h.

8. The preparation method according to claim 1, characterized in that: The oxidation-reduction reaction step and the step of preparing the ferromanganese phosphate precursor use alkaline solution to perform a first pH adjustment and a second pH adjustment.

9. The ferromanganese phosphate precursor obtained by the preparation method according to any one of claims 1 to 8.

10. A positive electrode material for a battery, characterized in that: It is prepared using the ferromanganese phosphate precursor described in claim 9.

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