Iron phosphate material and preparation method thereof, positive electrode material, positive electrode plate and secondary battery

Abstract

The invention provides an iron phosphate material and a preparation method thereof, a positive electrode material, a positive electrode plate and a secondary battery, in the iron phosphate material, the ratio of the sum of the amount of substance of a manganese element and an iron element to the amount of substance of a phosphorus element is (0.96-0.98): 1, and the content of the manganese element is 5200 ppm to 18100 ppm. The iron phosphate material has a high ratio of the sum of the amount of substance of the manganese element and the amount of substance of the iron element to the amount of substance of the phosphorus element, the purity of the iron phosphate material is high, and the electrochemical performance of the positive electrode material prepared by taking the iron phosphate material as the raw material at a low temperature can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of secondary batteries, in particular to a phosphorus iron material, a preparation method thereof, a positive electrode material, a positive electrode sheet and a secondary battery. BACKGROUND

[0002] Lithium iron phosphate (LiFePO4) material is widely used in new energy fields, such as secondary batteries of new energy vehicles. Due to the limitation of its own structure, the electrochemical performance of lithium iron phosphate material, especially at low temperature, is limited. Doping manganese element into lithium iron phosphate is one of the common ways to improve the electrochemical performance of lithium iron phosphate material (especially at low temperature). Manganese-doped phosphorus iron is a commonly used raw material for preparing manganese-doped lithium iron phosphate. The existing manganese-doped phosphorus iron preparation method introduces impurities into the phosphorus iron material, making it difficult to improve the purity of the existing phosphorus iron material. The electrochemical performance of manganese-doped lithium iron phosphate material prepared from the existing phosphorus iron material is difficult to improve.

[0003] Therefore, it is urgent to provide a phosphorus iron material, a preparation method thereof, a positive electrode material, a positive electrode sheet and a secondary battery, to solve the problem that the electrochemical performance of manganese-doped lithium iron phosphate material at low temperature needs to be improved due to the insufficient purity of the existing phosphorus iron material. SUMMARY

[0004] In view of the technical problems in the background art, the present application provides a phosphorus iron material, a preparation method thereof, a positive electrode material, a positive electrode sheet and a secondary battery, aiming to solve the technical problem that the electrochemical performance of manganese-doped lithium iron phosphate material at low temperature needs to be improved due to the insufficient purity of the existing phosphorus iron material.

[0005] In the first aspect, the embodiments of the present application provide a phosphorus iron material, wherein the ratio of the sum of the amount of substance of manganese element and iron element to the amount of substance of phosphorus element in the phosphorus iron material is (0.96-0.98):1, and the content of manganese element in the phosphorus iron material is 5200ppm-18100ppm.

[0006] In the technical scheme of the embodiments of the present application, the phosphorus iron material has a high ratio of the sum of the amount of substance of manganese element and iron element to the amount of substance of phosphorus element, and the purity of the phosphorus iron material is high, which is conducive to improving the electrochemical performance of the positive electrode material prepared from the phosphorus iron material at low temperature.

[0007] In some embodiments, the content of sulfur element and other metal elements except manganese element and iron element in the phosphorus iron material is less than or equal to 350ppm; and / or, In the iron phosphate material, the molar ratio of iron to phosphorus is 0.91 to 0.96.

[0008] In the above embodiments, the iron phosphate material has low impurity content, high crystallinity, and uniform manganese doping, which is beneficial to improving the electrochemical performance of the cathode material prepared using this iron phosphate material as raw material.

[0009] Secondly, embodiments of this application provide a method for preparing an iron phosphate material, comprising: The ferrous source, the first phosphorus source, and the first oxidant undergo a first mixing process to obtain the first slurry; The first slurry undergoes a first purification process to obtain a first filter cake; The first filter cake is mixed with a manganese source, a second phosphorus source, and a second oxidant in a second process to obtain a second slurry; The second pulp is aged to obtain aged pulp; The aged slurry undergoes a second purification treatment to obtain a second filter cake; The second filter cake was calcined to obtain ferric phosphate material; The first slurry comprises amorphous iron phosphate, and the second slurry comprises manganese phosphate complex; the manganese content in the iron phosphate material is 5200ppm~18100ppm.

[0010] In the technical solution of this application embodiment, the ferrous source, the first phosphorus source, and the first oxidant undergo a first mixing treatment to obtain a first slurry with amorphous iron phosphate. The manganese source, the second phosphorus source, and the second oxidant undergo a second mixing treatment to form a manganese phosphate complex, which is then mixed with the amorphous iron phosphate in the first filter cake. After aging, a second purification treatment, and calcination, iron phosphate material is obtained. In the second mixing treatment, the manganese phosphate complex is formed and mixed evenly with the amorphous iron phosphate. In the subsequent aging treatment, since the decomplexing product of the manganese phosphate complex is consistent with the lattice structure of iron phosphate, it is easy to uniformly dope into iron phosphate to form a manganese-iron solid solution, thereby obtaining a high-purity iron phosphate material.

[0011] In some embodiments, the step of obtaining a first slurry by first mixing the ferrous source, the first phosphorus source, and the first oxidant includes: A ferrous solution and a first solution are provided, wherein the first solution comprises the first phosphorus source and the first oxidant; The first solution is mixed with the ferrous solution at a first mixing temperature and for a first mixing time to obtain a first mixture; The first mixture is reacted at a first reaction temperature and for a first reaction time to obtain the first slurry; The first mixing temperature is 38-42 DEG C, the first mixing time is 10-30 minutes, the first reaction temperature is 40-65 DEG C, and the first reaction time is 40-60 minutes. The ratio of the amount of substance of the iron element in the ferrous solution, the phosphorus element in the first solution, and the first oxidizing agent in the first solution is 1:(1.01-1.05):(0.58-0.7).

[0012] In the above embodiments, the formation conditions of the first slurry and the ratio of the amounts of substance of the iron element, the phosphorus element, and the first oxidizing agent are controlled, which is beneficial to the sufficient reaction of the ferrous source, the first phosphorus source, and the first oxidizing agent, and improves the purity of the amorphous iron phosphate obtained in this step.

[0013] In some embodiments, the step of obtaining the second slurry by subjecting the first filter cake to a second mixing treatment with a manganese source, a second phosphorus source, and a second oxidizing agent comprises: A second solution is provided, which comprises the manganese source and the second phosphorus source; The second solution and the first filter cake are mixed at a second mixing temperature for a second mixing time to obtain a second mixture; The second mixture and the second oxidizing agent are mixed at a third mixing temperature for a third mixing time to obtain a third mixture; The third mixture is dispersed at a dispersion temperature for a dispersion time to obtain the second slurry; The second mixing temperature is 20-30 DEG C, the second mixing time is 8-12 minutes, the third mixing temperature is 20-30 DEG C, the third mixing time is 5-30 minutes, the dispersion temperature is 20-30 DEG C, and the dispersion time is 20-30 minutes. The ratio of the amount of substance of the manganese element in the manganese source to the iron element in the ferrous source is greater than 0:1 and less than or equal to 0.1:0.9; The valence of the manganese element in the manganese source is +2, and the amount of substance of the second oxidizing agent is 1-1.2 times the theoretical value required for oxidizing the manganese element in the manganese source; The ratio of the amount of substance of the iron element in the ferrous source to the phosphorus element in the second phosphorus source is 1:(0.15-0.3). In the above embodiments, controlling the formation conditions of the second slurry, as well as the amounts of manganese, phosphorus, and the second oxidant, is beneficial for the full formation of manganese phosphate complex. At the same time, controlling the molar ratio of manganese to iron in the ferrous source, and controlling the ratio of phosphorus in the second phosphorus source to iron in the ferrous source, is beneficial for controlling the amount of manganese doping in the iron phosphate material, thereby improving the electrochemical performance of the cathode material prepared using iron phosphate material as raw material.

[0014] In some embodiments, the step of aging the second slurry to obtain aged slurry includes: The second slurry is aged at an aging temperature and for an aging time to obtain an aged slurry; The aging temperature is 95℃~100℃, and the aging time is 1.5h~2.5h.

[0015] In the above embodiments, controlling the aging conditions is beneficial to the complete decomposition of manganese phosphate complex and the complete crystallization of iron phosphate, which in turn is beneficial to the uniform doping of manganese element into iron phosphate to form manganese-iron solid solution, thereby obtaining high-purity iron phosphate material.

[0016] In some embodiments, the step of calcining the second filter cake to obtain ferric phosphate material includes: The second filter cake is calcined at the specified temperature and for the specified time to obtain ferric phosphate material; The calcination temperature is 550℃~650℃, and the calcination time is 1.5h~2.5h.

[0017] In the above embodiments, controlling the calcination conditions is beneficial to the full calcination of the second filter cake, thereby improving the purity and crystallinity of the obtained iron phosphate material.

[0018] Thirdly, embodiments of this application provide a positive electrode material, which is prepared from the iron phosphate material as described above, or the positive electrode material is prepared from iron phosphate material prepared by the method described above.

[0019] In this embodiment, the positive electrode material is prepared from the iron phosphate material as described above or from the iron phosphate material prepared by the method described above, thus having the advantages of high purity and excellent electrochemical performance.

[0020] Fourthly, embodiments of this application provide a positive electrode sheet, including the positive electrode material as described above.

[0021] In this embodiment, the positive electrode sheet contains the above-mentioned positive electrode material, thus having the advantage of excellent electrochemical performance.

[0022] In a fifth aspect, the embodiments of the present application provide a secondary battery, comprising the positive electrode plate as described above.

[0023] In this embodiment, the secondary battery contains the positive electrode plate as described above, and thus has the advantage of excellent electrochemical performance.

[0024] In a sixth aspect, the embodiments of the present application provide an electric device, comprising the secondary battery as described above.

[0025] In this embodiment, the electric device contains the secondary battery as described above, and thus has the advantage of excellent electrochemical performance.

[0026] The above description is only a summary of the technical solutions of the present application, in order to more clearly understand the technical means of the present application, and can be implemented according to the content of the specification, and in order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the following specific embodiments of the present application are described. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the present application, the following will briefly introduce the drawings used in the present application. Obviously, the drawings described below are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0028] Figure 1 Process flow diagram of the preparation method of the iron phosphate material provided in the present application; Figure 2 XRD result graph of the iron phosphate material provided in embodiment 1 of the present application; Figure 3 SEM result graph of the iron phosphate material provided in embodiment 1 of the present application. DETAILED DESCRIPTION

[0029] The embodiments of the technical solutions of the present application will be described in detail below with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs; the terms used herein are only for the purpose of describing specific embodiments of the present application, and are not intended to limit the present application; the terms "include" and "have" and any variations thereof in the specification and claims of the present application and the above description of drawings are intended to cover non-exclusive inclusion.

[0031] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise explicitly and specifically limited.

[0032] Reference herein to "embodiments" means that a particular feature, structure, or characteristic described in connection with an embodiment can be included in at least one embodiment of the application. The appearance of the phrase in various places in the specification does not necessarily all refer to the same embodiment, nor is it necessarily independent or alternative embodiments to each other. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0033] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " in this paper generally represents that the front and rear associated objects are a "or" relationship.

[0034] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two), and similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0035] In the description of the embodiments of the present application, unless otherwise specified, "ppm" means the mass percentage of the tested element, molecule or ion in the sample.

[0036] In the description of the embodiments of the present application, unless otherwise specified, "content" means the mass percentage of the tested element, molecule or ion in the sample.

[0037] In the description of the embodiments of the present application, unless otherwise specified, the solvent used in the slurry, solution, and washing water is independently selected from at least one of distilled water, deionized water, secondary water, pure water, and ultrapure water.

[0038] The existing manganese iron phosphate preparation method introduces impurities into the iron phosphate material, making it difficult to improve the purity of the existing iron phosphate material, and the electrochemical performance of the manganese-doped lithium iron phosphate material obtained from the existing iron phosphate material is difficult to improve.

[0039] To solve the technical problem that the electrochemical performance of the manganese-doped lithium iron phosphate material needs to be improved due to the insufficient purity of the existing iron phosphate material, the application provides an iron phosphate material, a preparation method of the iron phosphate material, a positive electrode material, a positive electrode sheet, a secondary battery and an electric device, wherein the purity of the iron phosphate material is improved by increasing the ratio of the sum of the amount of substance of manganese and iron to the amount of substance of phosphorus in the iron phosphate material, so that the technical effect of improving the electrochemical performance of the positive electrode material prepared by taking the iron phosphate material as a raw material can be achieved, and the electrochemical performance of the positive electrode sheet, the secondary battery and the electric device is also improved.

[0040] The electric device provided by the embodiments of the application can be, but is not limited to, a mobile phone, a tablet computer, a notebook computer, an electric toy, an electric tool, an electric vehicle, an electric automobile, a ship, a spacecraft and the like. The electric toy can include a fixed or mobile electric toy, for example, a game console, an electric automobile toy, an electric ship toy and an electric aircraft toy, and the spacecraft can include an airplane, a rocket, a space shuttle and a spacecraft.

[0041] In a first aspect, the embodiments of the application provide an iron phosphate material, wherein the ratio of the sum of the amount of substance of manganese and iron to the amount of substance of phosphorus in the iron phosphate material is (0.96-0.98):1, and the content of manganese in the iron phosphate material is 5200 ppm-18100 ppm.

[0042] In the technical solution of the embodiments of the application, the iron phosphate material has a high ratio of the sum of the amount of substance of manganese and iron to the amount of substance of phosphorus, and the purity of the iron phosphate material is high, which is beneficial to improving the electrochemical performance of the positive electrode material prepared by taking the iron phosphate material as a raw material, especially the electrochemical performance of the positive electrode material at low temperature.

[0043] In some embodiments, the ratio of the amount of substance of iron to the amount of substance of phosphorus in the iron phosphate material is 0.855-0.960, the iron phosphate material has a higher iron-phosphorus ratio, which is beneficial to improving the structural stability of the positive electrode material prepared by taking the iron phosphate material as a raw material, thereby being beneficial to improving the electrochemical performance stability of the positive electrode material prepared by taking the iron phosphate material as a raw material.

[0044] In some embodiments, the ratio of the amount of substance of iron to the amount of substance of phosphorus in the iron phosphate material is 0.947-0.951.

[0045] In some embodiments, the content of manganese element in the iron phosphate material is 5200 ppm to 18100 ppm. By controlling the content of manganese element doped in the iron phosphate material, it is beneficial to maintain the structural stability of the iron phosphate material while improving the electrochemical performance of the positive electrode material prepared by using the iron phosphate material as raw material, such as the electronic conductivity and ion diffusion rate, especially the electronic conductivity and ion diffusion rate at low temperature.

[0046] In some embodiments, the content of manganese element in the iron phosphate material is 7200 ppm to 7600 ppm.

[0047] In some embodiments, the content of sulfur element and other metal elements except manganese element and iron element in the iron phosphate material is less than or equal to 350 ppm. Further, the content of sulfur element and other metal elements except manganese element and iron element in the iron phosphate material is 50 ppm to 350 ppm.

[0048] In some embodiments, the content of sulfur element in the iron phosphate material is 8 ppm to 20 ppm.

[0049] In some embodiments, the content of calcium element in the iron phosphate material is 1 ppm to 8.5 ppm. Further, the content of calcium element in the iron phosphate material is 1 ppm to 7.5 ppm.

[0050] In some embodiments, the content of cobalt element in the iron phosphate material is 0 ppm to 2.6 ppm.

[0051] In some embodiments, the content of potassium element in the iron phosphate material is 40 ppm to 380 ppm. Further, the content of potassium element in the iron phosphate material is 40 ppm to 300 ppm. Still further, the content of potassium element in the iron phosphate material is 40 ppm to 150 ppm.

[0052] In some embodiments, the content of magnesium element in the iron phosphate material is 0 ppm to 39 ppm.

[0053] In some embodiments, the content of magnesium element in the iron phosphate material is 0 ppm to 11 ppm. Further, the content of magnesium element in the iron phosphate material is 0 ppm to 8.5 ppm.

[0054] In some embodiments, the content of nickel element in the iron phosphate material is 0 ppm to 5 ppm.

[0055] In some embodiments, the content of zinc element in the iron phosphate material is 0 ppm to 5 ppm.

[0056] In some embodiments, the low impurity element content in the iron phosphate material indicates high purity of the manganese iron phosphate in the iron phosphate material, which is conducive to improving the electrochemical performance of the positive electrode material prepared by using the iron phosphate material as a raw material.

[0057] In some embodiments, when the positive electrode material prepared by using the iron phosphate material as a raw material is applied to a secondary battery, the discharge specific capacity at 0.1C rate is 148 mAh / g-160 mAh / g at 25°C; more preferably, the discharge specific capacity at 0.1C rate is 155 mAh / g-160 mAh / g at 25°C.

[0058] In some embodiments, when the positive electrode material prepared by using the iron phosphate material as a raw material is applied to a secondary battery, the discharge specific capacity at 0.1C rate is 115 mAh / g-129.5 mAh / g at -20°C; more preferably, the discharge specific capacity at 0.1C rate is 120 mAh / g-129.5 mAh / g at -20°C.

[0059] In some embodiments, when the positive electrode material prepared by using the iron phosphate material as a raw material is applied to a secondary battery, the discharge specific capacity retention rate at 0.1C rate is 78%-81.5% at -20°C.

[0060] Please refer to Figure 1 In a second aspect, the embodiments of the present application provide a preparation method of an iron phosphate material, comprising: The ferrous source, the first phosphorus source and the first oxidizing agent are subjected to first mixing treatment to obtain a first slurry; The first slurry is subjected to first purification treatment to obtain a first filter cake; The first filter cake, the manganese source, the second phosphorus source and the second oxidizing agent are subjected to second mixing treatment to obtain a second slurry; The second slurry is subjected to aging treatment to obtain an aged slurry; The aged slurry is subjected to second purification treatment to obtain a second filter cake; The second filter cake is subjected to calcination treatment to obtain an iron phosphate material; The first slurry comprises amorphous iron phosphate, and the second slurry comprises a manganese phosphate complex. The content of manganese element in the iron phosphate material is 5200 ppm-18100 ppm.

[0061] In the technical scheme of the embodiment of the present application, the ferrous source, the first phosphorus source and the first oxidizing agent are subjected to first mixing treatment to obtain the first slurry with amorphous ferric phosphate, the manganese source, the second phosphorus source and the second oxidizing agent are subjected to second mixing treatment to form a manganese phosphate complex, and the manganese phosphate complex is mixed with the amorphous ferric phosphate in the first filter cake, and then subjected to aging treatment, second purification treatment and calcination treatment to obtain the ferric phosphate material; wherein the manganese phosphate complex is formed through the second mixing treatment and is uniformly mixed with the amorphous ferric phosphate, and in the subsequent aging treatment, the decomplexation product of the manganese phosphate complex is consistent with the crystal lattice structure of the ferric phosphate, so that the manganese iron solid solution is easily and uniformly doped in the ferric phosphate, thereby obtaining the ferric phosphate material with high purity.

[0062] In some embodiments, the present application provides a preparation method of the ferric phosphate material.

[0063] In some embodiments, the step of obtaining the first slurry by subjecting the ferrous source, the first phosphorus source and the first oxidizing agent to first mixing treatment comprises: providing a ferrous solution and a first solution, wherein the first solution comprises the first phosphorus source and the first oxidizing agent; mixing the first solution with the ferrous source at a first mixing temperature for a first mixing time to obtain a first mixture; subjecting the first mixture to a first reaction at a first reaction temperature for a first reaction time to obtain the first slurry.

[0064] In some embodiments, the first mixing temperature is 38-42℃, the first mixing time is 10-30min, the first reaction temperature is 40-65℃, and the first reaction time is 40-60min.

[0065] In some embodiments, the molar ratio of the iron element in the ferrous solution, the phosphorus element in the first solution and the first oxidizing agent in the first solution is 1:(1.01-1.03):(0.55-0.65).

[0066] Controlling the formation conditions of the first slurry and the molar ratio of the iron element, the phosphorus element and the first oxidizing agent is beneficial to the sufficient reaction of the ferrous source, the first phosphorus source and the first oxidizing agent, and improves the purity of the amorphous ferric phosphate obtained in this step.

[0067] In some embodiments, the ferrous solution can be a ferrous salt solution, and the ferrous salt can be at least one selected from the group consisting of anhydrous ferrous sulfate, ferrous chloride, ferrous nitrate, ferrous sulfate heptahydrate and the like.

[0068] In some embodiments, the first phosphorus source can be selected from phosphate salts, for example, can be at least one selected from the group consisting of ammonium dihydrogen phosphate, diammonium hydrogen phosphate, sodium dihydrogen phosphate, disodium hydrogen phosphate and the like.

[0069] In some embodiments, the first oxidizing agent can be selected from hydrogen peroxide. When the first oxidizing agent is selected from hydrogen peroxide, the mass fraction of hydrogen peroxide in the hydrogen peroxide can be 26% to 29%, for example, can be 26%, 27%, 28%, 29%, etc.

[0070] The above-mentioned ferrous salt, the first phosphorus source, and the first oxidizing agent are inexpensive and widely available, which is conducive to reducing the preparation cost of the iron phosphate material and facilitating large-scale industrial preparation.

[0071] In some embodiments, the concentration of ferrous ions in the ferrous solution can be 0.5 mol / L to 1.5 mol / L, for example, can be 0.5 mol / L, 0.75 mol / L, 1 mol / L, 1.25 mol / L, 1.5 mol / L, etc.

[0072] In some embodiments, the mass fraction of the first phosphorus source in the first solution can be 3% to 9%, for example, can be 3%, 4.5%, 5%, 6%, 7.5%, 9%, etc.

[0073] By controlling the concentration of ferrous ions in the ferrous solution and the mass fraction of the first phosphorus source in the first solution within the above ranges, respectively, it is conducive to adjusting the ratio of the first solution and the ferrous solution participating in the mixing, facilitating the full reaction of iron elements and phosphorus elements, and regulating the solid content of the obtained first slurry, so as to obtain a first slurry with appropriate viscosity.

[0074] In some embodiments, the amount-of-substance ratio of iron elements in the ferrous solution, phosphorus elements in the first solution, and the first oxidizing agent in the first solution is 1:(1.01-1.05):(0.58-0.7), and the first oxidizing agent fully oxidizes the ferrous ions, thereby facilitating the full reaction of iron elements and phosphorus elements. For example, the amount-of-substance ratio of iron elements in the ferrous solution, phosphorus elements in the first solution, and the first oxidizing agent in the first solution can be 1:1.01:0.58, 1:1.01:0.6, 1:1.01:0.65, 1:1.02:0.55, 1:1.02:0.6, 1:1.02:0.65, 1:1.03:0.55, 1:1.03:0.6, 1:1.03:0.65, 1:1.05:0.7, etc.

[0075] In some embodiments, in the step of mixing the first solution in the ferrous solution at a first mixing temperature for a first mixing time to obtain a first mixture, the first solution is mixed in the ferrous solution under stirring of the ferrous solution, which is conducive to the full mixing of the first solution and the ferrous solution and reduces the generation of impurities due to local over-concentration of the first solution.

[0076] In some embodiments, the stirring speed of the ferrous solution is 400 r / min to 500 r / min, for example, it can be 400 r / min, 420 r / min, 450 r / min, 475 r / min, 500 r / min, etc.

[0077] In some embodiments, the first mixing temperature is 38°C to 42°C, and the first mixing time is 10 min to 30 min, which is conducive to the sufficient mixing of the first phosphorus source, the first oxidizing agent in the first solution and the ferrous ions in the ferrous solution. Wherein, the first mixing temperature can be 38°C, 39°C, 40°C, 41°C, 42°C, etc., and the first mixing time can be 10 min, 15 min, 20 min, 25 min, 30 min, etc.

[0078] In some embodiments, the step of obtaining the first slurry by mixing the ferrous source, the first phosphorus source and the first oxidizing agent at a first mixing temperature for a first mixing time is carried out under stirring to facilitate the sufficient and uniform reaction, and the stirring speed can be 400 r / min to 500 r / min, for example, it can be 400 r / min, 420 r / min, 450 r / min, 475 r / min, 500 r / min.

[0079] In some embodiments, the first reaction temperature is 40°C to 65°C, and the first reaction time is 40 min to 60 min, which is conducive to the sufficient reaction of the ferrous ions in the ferrous salt solution, the phosphate ions in the first solution and the first oxidizing agent in the first solution, thereby obtaining the first slurry. Wherein, the first reaction temperature can be 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, etc., and the first reaction time can be 40 min, 45 min, 50 min, 55 min, 60 min, etc.

[0080] In some embodiments, the ferrous source, the first phosphorus source and the first oxidizing agent are subjected to first mixing treatment to obtain the first slurry, and the first slurry obtained has amorphous iron phosphate, and the reaction equation is as follows: 2Fe 2+ +2H2PO4 - +H2O2+(X-1)H2O=2FePO4·XH2O↓+2H + By controlling the formation of the first slurry under the above conditions, the sufficient reaction of the ferrous source, the first phosphorus source and the first oxidizing agent is facilitated, and the purity of the amorphous iron phosphate obtained in this step is improved.

[0081] In some embodiments, the solid content of the first slurry is 12% to 20%, i.e., the mass fraction of solid particles in the first slurry is 12% to 20%, which can be 12%, 15%, 16%, 18%, 20%, etc. The suitable solid content of the first slurry is conducive to efficient reaction while avoiding excessive viscosity of the first slurry due to high solid content. Thus, problems such as blockage affecting production are avoided.

[0082] In some embodiments, the first slurry is subjected to a first purification treatment, and the step of obtaining the first filter cake comprises: The first slurry is subjected to a first solid-liquid separation treatment to obtain a first solid material; The first solid material is subjected to a first washing treatment to obtain a first washed material; The first washed material is subjected to a second solid-liquid separation treatment to obtain the first filter cake.

[0083] In some embodiments, the first solid-liquid separation treatment and the second solid-liquid separation treatment are independently selected from commonly used solid-liquid separation methods such as plate pressure filtration, atmospheric pressure filtration, pressure filtration, suction filtration, centrifugation, etc.

[0084] In some embodiments, the first solid material is subjected to a first washing treatment to obtain a first washed material, and the step comprises: The first solid material is washed with a first washing liquid until the conductivity of the first washing liquid after washing is less than or equal to 3.5 ms / cm to obtain the first washed material.

[0085] In some embodiments, the water content of the first filter cake is less than or equal to 60% to 70%, for example, it can be 60%, 62%, 65%, 68%, 70%, etc.

[0086] In some embodiments, the first filter cake is subjected to a second mixing treatment with a manganese source, a second phosphorus source, and a second oxidizing agent to obtain a second slurry, and the step comprises: A second solution is provided, which comprises the manganese source and the second phosphorus source; The second solution and the first filter cake are mixed at a second mixing temperature for a second mixing time to obtain a second mixture; The second mixture and the second oxidizing agent are mixed at a third mixing temperature for a third mixing time to obtain a third mixture; The third mixture is dispersed at a dispersion temperature for a dispersion time to obtain the second slurry.

[0087] In some embodiments, the valence of manganese in the manganese source is +2, and the manganese source is selected from at least one of anhydrous manganese sulfate (II), anhydrous manganese chloride (II), manganese sulfate (II) monohydrate, and manganese chloride (II) tetrahydrate.

[0088] In some embodiments, the second phosphorus source is selected from phosphoric acid. The second phosphorus source is selected from phosphoric acid, which is conducive to controlling the pH value of the third mixture within the range of 1.6±0.15 and controlling the dispersion of the third mixture under the condition that the pH value is within the range of 1.6±0.15 at the dispersion temperature and the dispersion time, thereby obtaining the second slurry, which is conducive to reducing the precipitation of impurity elements and improving the purity of the final obtained iron phosphate material.

[0089] In some embodiments, the second oxidizing agent is selected from at least one of potassium permanganate and ammonium persulfate.

[0090] The above-mentioned manganese source, second phosphorus source, and second oxidizing agent are inexpensive and widely available, which is conducive to reducing the preparation cost of the iron phosphate material and facilitating large-scale industrial preparation.

[0091] In some embodiments, the valence of the manganese element in the manganese source is +2, and the amount of substance of the second oxidizing agent is 1 to 1.2 times the theoretical value required for oxidizing the manganese element in the manganese source, for example, 1 times, 1.02 times, 1.05 times, 1.08 times, 1.1 times, 1.12 times, 1.15 times, 1.18 times, etc.

[0092] In some embodiments, when the second oxidizing agent is selected from potassium permanganate, the centralization reaction of the manganese element is utilized, which is conducive to obtaining a manganese phosphate complex and reducing the formation of other anions, thereby saving the cost of treating other anions and reducing the preparation cost of the iron phosphate material. Specifically, when the second oxidizing agent is selected from potassium permanganate, the reaction for generating the manganese phosphate complex is as follows: 8H + +MnO4 - +4Mn 2+ +10PO4 3- =5[Mn(PO4)2] 3- +4H2O In some embodiments, when the second oxidizing agent is selected from ammonium persulfate, the step of mixing the second mixture with the second oxidizing agent at a third mixing temperature for a third mixing time to obtain a third mixture includes: The second mixture is mixed with the second oxidizing agent and a catalyst at a third mixing temperature for a third mixing time to obtain a third mixture.

[0093] In some embodiments, when the second oxidizing agent is selected from ammonium persulfate, the catalyst can be a silver salt, for example, silver nitrate. Specifically, when the second oxidizing agent is selected from ammonium persulfate and the catalyst is selected from silver nitrate, the reaction for generating the manganese phosphate complex is as follows: 5S2O8 2- +6Mn 2+ +20PO43- Ag+ = 10[Mn(PO4)2] 3- +10SO4 2- In some embodiments, the molar ratio of the manganese element in the manganese source to the iron element in the ferrous source is greater than 0:1 and less than or equal to 0.1:0.9, for example, the molar ratio of the manganese element in the manganese source to the iron element in the ferrous source can be 0.01:0.99, 0.02:0.98, 0.03:0.97, 0.04:0.96, 0.05:0.95, 0.06:0.94, 0.07:0.93, 0.08:0.92, 0.09:0.91, 0.1:0.9, etc.

[0094] In some embodiments, the molar ratio of the iron element in the ferrous source to the phosphorus element in the second phosphorus source is 1:(0.15~0.3), for example, the molar ratio of the iron element in the ferrous source to the phosphorus element in the second phosphorus source can be 1:0.15, 1:0.2, 1:0.25, 1:0.3, etc. Further, the molar ratio of the iron element in the ferrous source to the phosphorus element in the second phosphorus source is 1:(0.2~0.3).

[0095] By controlling the molar ratio of the manganese element in the manganese source to the iron element in the ferrous source, and controlling the molar ratio of the iron element in the ferrous source to the phosphorus element in the second phosphorus source, it is beneficial to control the molar ratio of the manganese element in the manganese source to the phosphorus element in the second phosphorus source to fully react to form the manganese phosphate complex, and to control the molar ratio of the manganese phosphate complex to the amorphous ferric phosphate in the first filter cake, so as to control the amount of manganese element doped into the ferric phosphate, and to improve the electrochemical performance of the positive electrode material obtained by using the prepared ferric phosphate material as a raw material.

[0096] In some embodiments, the molar ratio of the manganese element in the manganese source to the second oxidizing agent is (4~6):(1~5.2), for example, the molar ratio of the manganese element in the manganese source to the second oxidizing agent can be 4:1, 4:1.1, 4:1.2, 6:5, 6:5.1, 6:5.2, etc., which is beneficial to fully oxidize the divalent manganese in the manganese source to trivalent manganese in the manganese phosphate complex. According to the different second oxidizing agents, the molar ratio of the manganese element in the manganese source to the second oxidizing agent is different. When the second oxidizing agent is potassium permanganate, the molar ratio of the manganese element in the manganese source to the second oxidizing agent can be 4:(1~1.2), for example, it can be 4:1, 4:1.1, 4:1.2, etc. When the second oxidizing agent is ammonium persulfate, the molar ratio of the manganese element in the manganese source to the second oxidizing agent can be 6:(5~5.2), for example, it can be 6:5, 6:5.1, 6:5.2.

[0097] In some embodiments, when the second oxidizing agent is selected from ammonium persulfate, the catalyst is silver ions, and the molar ratio of manganese elements in the manganese source, the second oxidizing agent, and the silver ions in the catalyst can be 6:(5~5.2):(0.18~0.22), which is conducive to the sufficient reaction of oxidizing divalent manganese in the manganese source to trivalent manganese in the manganese phosphate complex. For example, the molar ratio of manganese elements in the manganese source, the second oxidizing agent, and the silver ions in the catalyst can be 6:5:0.18, 6:5:0.2, 6:5:0.22, 6:5.1:0.18, 6:5.1:0.2, 6:5.1:0.22, 6:5.2:0.18, 6:5.2:0.2, 6:5.2:0.22, and the like.

[0098] In some embodiments, the second mixing temperature is 20℃~30℃, and the second mixing time is 8min~12min.

[0099] In some embodiments, the third mixing temperature is 20℃~30℃, and the third mixing time is 5min~30min. For example, the third mixing temperature can be 20℃, 24℃, 25℃, 26℃, 28℃, 30℃, and the like; the third mixing time can be 5min, 8min, 10min, 12min, 15min, 18min, 20min, 24min, 25min, 28min, 30min, and the like.

[0100] In some embodiments, the dispersion temperature is 20℃~30℃, and the dispersion time is 20min~30min. For example, the dispersion temperature can be 20℃, 24℃, 25℃, 26℃, 28℃, 30℃, and the like; the dispersion time can be 20min, 22min, 25min, 28min, 30min, and the like.

[0101] In some embodiments, as the silver ions for catalysis, the silver ions can be recovered by cation adsorption resin. Specifically, the filtrate and washing water containing silver ions are collected, adsorbed by strong acid cation resin, eluted by 0.5 mol / L thiourea solution in countercurrent, collected the eluate containing silver ions, and finally electrolyzed to obtain silver powder, so as to save the manufacturing cost.

[0102] In some embodiments, the second solution is mixed with the first filter cake at a second mixing temperature for a second mixing time to obtain a second mixture; the second mixture is mixed with the second oxidizing agent at a third mixing temperature for a third mixing time to obtain a third mixture; and the third mixture is dispersed at a dispersion temperature for a dispersion time to obtain the second slurry, each independently under stirring at a stirring speed of 800 r / min to 1200 r / min, for example, 800 r / min, 850 r / min, 900 r / min, 950 r / min, 1000 r / min, 1050 r / min, 1100 r / min, 1150 r / min, 1200 r / min, or the like.

[0103] By controlling the formation conditions of the second slurry, the manganese phosphate complex is advantageously fully formed, and the formed manganese phosphate complex is advantageously fully and uniformly mixed with the amorphous iron phosphate in the first filter cake.

[0104] In some embodiments, the second slurry is subjected to an aging treatment to obtain an aged slurry, and the step of aging the second slurry comprises: The second slurry is aged at an aging temperature for an aging time to obtain an aged slurry.

[0105] In some embodiments, the aging temperature is 95°C to 100°C, and the aging time is 1.5 h to 2.5 h. For example, the aging temperature can be 95°C, 96°C, 97°C, 98°C, 99°C, 100°C, or the like, and the aging time can be 1.5 h, 1.6 h, 1.8 h, 2 h, 2.2 h, 2.4 h, 2.5 h, or the like.

[0106] In some embodiments, in the aging treatment, the pH value is controlled to be in a range of 1.6 ± 0.15, which is advantageous for reducing the precipitation of impurity elements and improving the purity of the finally obtained iron phosphate material.

[0107] In the aging process, the manganese phosphate complex is fully decomposed and precipitated homogeneously, and combines with the iron phosphate to form manganese iron phosphate, and the reaction equation is as shown below: 9FePO4·XH2O + 1[Mn(PO4)2] 3- ==10Fe 0.9 Mn 0.1 PO4·2H2O + PO4 3- + (9X-2)H2O Controlling the conditions of the aging treatment is advantageous for fully decomposing the manganese phosphate complex and fully crystallizing the iron phosphate, and further advantageous for uniformly doping the manganese element in the iron phosphate to form a manganese iron solid solution, thereby obtaining an iron phosphate material with high purity.

[0108] In some embodiments, the step of subjecting the aging slurry to a second purification treatment to obtain a second filter cake comprises: The aging slurry is subjected to a third solid-liquid separation treatment to obtain a second solid material; The second solid material is subjected to a second washing treatment to obtain a second washed material; The second washed material is subjected to a fourth solid-liquid separation treatment to obtain a second filter cake.

[0109] In some embodiments, the third solid-liquid separation treatment and the fourth solid-liquid separation treatment are independently selected from commonly used solid-liquid separation methods such as plate pressure filtration, atmospheric pressure filtration, pressure filtration, suction filtration, centrifugation, etc.

[0110] In some embodiments, the step of subjecting the second solid material to a second washing treatment to obtain a second washed material comprises: The second solid material is washed with a second washing liquid until the conductivity of the second washing liquid after washing is less than or equal to 350 μs / cm to obtain a second washed material.

[0111] In some embodiments, the water content of the second filter cake is less than or equal to 40% to 60%, for example, it can be 40%, 45%, 50%, 55%, 60%, etc.

[0112] In some embodiments, the step of subjecting the second filter cake to a calcination treatment to obtain a ferric phosphate material comprises: The second filter cake is subjected to a calcination treatment at a calcination temperature for a calcination time to obtain a ferric phosphate material; In some embodiments, the calcination temperature is 550°C to 650°C, and the calcination time is 1.5 h to 2.5 h. For example, the calcination temperature can be 550°C, 575°C, 600°C, 625°C, 650°C, etc., and the calcination time can be 1.5 h, 1.6 h, 1.8 h, 2 h, 2.2 h, 2.4 h, 2.5 h, etc.

[0113] Controlling the conditions of the calcination treatment is beneficial for the complete calcination of the second filter cake and improves the purity and crystallinity of the obtained ferric phosphate material.

[0114] In some embodiments, before the second filter cake is subjected to the calcination treatment, the second filter cake is further subjected to a drying treatment.

[0115] In some embodiments, the drying treatment can be performed by atmospheric drying, vacuum drying, etc. When the drying treatment is performed by atmospheric drying, the drying temperature can be 95°C to 100°C, and the drying time can be 10 h to 14 h. For example, the drying temperature can be 95°C, 96°C, 97°C, 98°C, 99°C, 100°C, etc., and the drying time can be 10 h, 11 h, 12 h, 13 h, 14 h, etc.

[0116] By drying the second filter cake, the reaction by-products generated in the calcination process can be reduced, and the purity of the obtained iron phosphate material can be further improved.

[0117] In a third aspect, the embodiments of the present application provide a positive electrode material, which is prepared from the iron phosphate material as described above, or which is prepared from the iron phosphate material prepared by the preparation method of the iron phosphate material as described above.

[0118] In this embodiment, the positive electrode material is prepared from the iron phosphate material as described above or from the iron phosphate material prepared by the preparation method of the iron phosphate material as described above, and thus has the advantages of high purity and excellent electrochemical performance.

[0119] In a fourth aspect, the embodiments of the present application provide a positive electrode tab, which comprises the positive electrode material as described above.

[0120] In this embodiment, the positive electrode tab comprises the positive electrode material as described above, and thus has the advantage of excellent electrochemical performance.

[0121] In a fifth aspect, the embodiments of the present application provide a secondary battery, which comprises the positive electrode tab as described above.

[0122] In this embodiment, the secondary battery comprises the positive electrode tab as described above, and thus has the advantage of excellent electrochemical performance.

[0123] In a sixth aspect, the embodiments of the present application provide an electric device, which comprises the secondary battery as described above.

[0124] In this embodiment, the electric device comprises the secondary battery as described above, and thus has the advantage of excellent electrochemical performance.

[0125] Some specific embodiments are listed below. It should be noted that the embodiments described below are exemplary and are only used to explain the present application, and cannot be understood as a limitation of the present application. If the specific technology or condition is not specified in the embodiments, the technology or condition described in the literature in the art or according to the product manual is used. If the reagent or instrument is not specified by the manufacturer, it is a conventional product that can be obtained by market purchase.

[0126] I. Preparation method Embodiment 1 S100: ferrous sulfate, pure water to prepare a 1 mol / L concentration of ferrous sulfate solution (ferrous solution), phosphorus salt (the first phosphorus source, a phosphorus salt solution obtained by mixing ammonium dihydrogen phosphate solution and ammonia water, pH value is 7.0), pure water, hydrogen peroxide (the first oxidizing agent, the mass fraction of hydrogen peroxide is 27%) are weighed to prepare a 5% (phosphorus element mass fraction) phosphorus salt solution (the first solution), the material amount ratio of ferrous sulfate: phosphorus salt: hydrogen peroxide is 1:1.02:0.6, the phosphorus salt solution is added dropwise into the ferrous sulfate solution under the stirring condition of a first mixing temperature of 40℃ and a rotation speed of 500r / min within a first mixing time of 20min, the rotation speed is maintained at 500r / min, a first reaction temperature is 55℃, and a first reaction time is 50min, and a first slurry with amorphous iron phosphate is obtained.

[0127] S200: the first slurry is filtered by a plate pressure filter to obtain a first solid material, the first solid material in the cavity of the plate pressure filter is washed with pure water until the conductivity of the washed water is less than or equal to 3.5ms / cm to obtain a first washed material, the first washed material is removed from the plate pressure filter after the pressure relief and discharging procedures, and a first filter cake is obtained.

[0128] S300: the manganese source is manganese sulfate, the second oxidizing agent is potassium permanganate, and the second phosphorus source is phosphoric acid, the material amount ratio of the iron element in the ferrous solution used in step S100 to the manganese element in the manganese source is 0.98:0.02, the material amount ratio of the iron element in the ferrous solution used in step S100 to the phosphorus element in the second phosphorus source is 1:0.2, the manganese source and the second phosphorus source are weighed and dissolved in pure water as a second solution, the second solution and the first filter cake are mixed under the stirring condition of a second mixing temperature of 25℃ and a rotation speed of 1000r / min for a second mixing time of 10min to obtain a second mixture, the material amount ratio of the manganese element in the manganese source to the second oxidizing agent is 4:1.1, the second oxidizing agent is weighed, the rotation speed is maintained unchanged, the second mixture and the second oxidizing agent are mixed at a third mixing temperature of 25℃ for a third mixing time of 20min to obtain a third mixture, the pH value of the phosphoric acid control system is in the range of 1.6±0.15, and the third mixture is dispersed at a dispersion temperature of 25℃ for a dispersion time of 20min to obtain a second slurry.

[0129] S400: the second slurry is aged in a reaction kettle, the pH value is controlled in the range of 1.6±0.15 during the aging process, the stirring speed is 500r / min, the aging temperature is 98℃, the aging time is 2h, the manganese phosphate complex is decomplexed and homogeneously precipitated to enable the manganese element to be doped into the iron phosphate, the color of the precipitate changes from yellow to blue-violet, and an aged slurry is obtained.

[0130] S500: The aging slurry is filtered by a plate press to obtain a second solid material, and pure water is used to wash the second solid material in the cavity of the plate press filter until the conductivity of the washed water is less than or equal to 350 us / cm to obtain a second washed material, and the second washed material is removed from the plate press filter after pressure relief and discharging to obtain a second filter cake.

[0131] S600: The second filter cake is subjected to normal pressure drying treatment at a drying temperature of 98 ℃ for 12 h to obtain a dried material, and the dried material is calcined at a calcination temperature of 600 ℃ for 2 h to obtain an iron phosphate material.

[0132] The XRD (X-ray diffraction) result of the iron phosphate material obtained in Example 1 is shown in Figure 2 , and the SEM (scanning electron microscope) result is shown in Figure 3 .

[0133] Example 2 S100: Ferrous sulfate, pure water are weighed to prepare a 0.5 mol / L ferrous sulfate solution (ferrous solution), a phosphorus salt (first phosphorus source, a phosphorus salt solution obtained by mixing ammonium dihydrogen phosphate solution and ammonia water, with a pH value of 6.8), pure water, hydrogen peroxide (first oxidizing agent, with a hydrogen peroxide mass fraction of 26%) are weighed to prepare a 3% (based on the mass fraction of phosphorus element) phosphorus salt solution (first solution), and the phosphorus salt solution is added dropwise into the ferrous sulfate solution under stirring at a first mixing temperature of 38 ℃ and a rotation speed of 400 r / min for a first mixing time of 10 min, and the first reaction is carried out at a first reaction temperature of 40 ℃ and a rotation speed of 400 r / min for a first reaction time of 40 min to obtain a first slurry with amorphous iron phosphate.

[0134] S200: The first slurry is filtered by a plate press to obtain a first solid material, and pure water is used to wash the first solid material in the cavity of the plate press filter until the conductivity of the washed water is less than or equal to 3.5 ms / cm to obtain a first washed material, and the first washed material is removed from the plate press filter after pressure relief and discharging to obtain a first filter cake.

[0135] S300: the manganese source is manganese sulfate, the second oxidizing agent is potassium permanganate, the second phosphorus source is phosphoric acid, the molar ratio of the iron element in the ferrous solution used in step S100 to the manganese element in the manganese source is 0.98:0.2, the molar ratio of the iron element in the ferrous solution used in step S100 to the phosphorus element in the second phosphorus source is 1:0.2, the manganese source and the second phosphorus source are weighed and dissolved in pure water to obtain a second solution, the second solution and the first filter cake are mixed at a second mixing temperature of 20°C, a stirring speed of 800r / min, and for a second mixing time of 8min to obtain a second mixture; the second oxidizing agent is weighed according to a molar ratio of the manganese element in the manganese source to the second oxidizing agent of 4:1.1, the stirring speed is kept unchanged, the second mixture and the second oxidizing agent are mixed at a third mixing temperature of 20°C for a third mixing time of 5min to obtain a third mixture, the pH value of the phosphoric acid control system is controlled within a range of 1.6±0.15, and the third mixture is dispersed at a dispersion temperature of 20°C for a dispersion time of 20min to obtain a second slurry.

[0136] S400: the second slurry is aged in a reaction kettle, the pH value is controlled within a range of 1.6±0.15 during the aging process, the stirring speed is 500r / min, the aging temperature is 95°C, and the aging time is 1.5h, the manganese phosphate complex is decomplexed and homogeneously precipitated to dope the manganese element into the iron phosphate, the color of the precipitate changes from yellow to blue-violet, and an aged slurry is obtained.

[0137] S500: the aged slurry is filtered through a plate press to obtain a second solid material, the second solid material in the cavity of the plate press filter is washed with pure water until the conductivity of the washed water is less than or equal to 350us / cm to obtain a second washed material, the second washed material is removed from the plate press filter after the pressure relief and discharging procedures, and a second filter cake is obtained.

[0138] S600: the second filter cake is subjected to normal pressure drying treatment, the drying temperature is 95°C, the drying time is 10h, a dried material is obtained; the dried material is calcined at a calcination temperature of 550°C for a calcination time of 1.5h, and an iron phosphate material is obtained.

[0139] Example 3 S100: ferrous sulfate, pure water to prepare a 1.5 mol / L concentration of ferrous sulfate solution (ferrous solution), phosphorus salt (the first phosphorus source, a phosphorus salt solution obtained by mixing ammonium dihydrogen phosphate solution and ammonia water, pH value is 7.2), pure water, hydrogen peroxide (the first oxidizing agent, hydrogen peroxide mass fraction is 29%) are weighed to prepare a 9% (phosphorus element mass fraction) phosphorus salt solution (the first solution), the material amount ratio of ferrous sulfate: phosphorus salt: hydrogen peroxide is 1:1.02:0.6, the phosphorus salt solution is added dropwise into the ferrous sulfate solution under the stirring condition of the first mixing temperature 42℃ and the rotation speed 450r / min within the first mixing time 30min, the rotation speed is maintained at 450r / min, the first reaction temperature is 65℃, the first reaction time is 60min, and the first slurry with amorphous iron phosphate is obtained.

[0140] S200: the first slurry is filtered by plate pressure to obtain the first solid material, the first solid material in the cavity of the plate pressure filter is washed with pure water until the conductivity of the washed water is less than or equal to 3.5ms / cm to obtain the first washed material, the first washed material is removed from the plate pressure filter after the pressure relief and discharging procedures, and the first filter cake is obtained.

[0141] S300: the manganese source is manganese sulfate, the second oxidizing agent is potassium permanganate, and the second phosphorus source is phosphoric acid, the material amount ratio of the iron element of the ferrous solution used in step S100 to the manganese element in the manganese source is 0.98:0.2, the material amount ratio of the iron element of the ferrous solution used in step S100 to the phosphorus element in the second phosphorus source is 1:0.2, the manganese source and the second phosphorus source are weighed and dissolved in pure water as a second solution, the second solution and the first filter cake are mixed under the stirring of the second mixing temperature 30℃ and the rotation speed 1200r / min for the second mixing time 12min to obtain a second mixture, the material amount ratio of the manganese element in the manganese source to the second oxidizing agent is 4:1.1, the second mixture and the second oxidizing agent are mixed at the third mixing temperature 30℃ for the third mixing time 30min to obtain a third mixture, the pH value of the phosphoric acid control system is in the range of 1.6±0.15, and the third mixture is dispersed at the dispersion temperature 30℃ for the dispersion time 30min to obtain a second slurry.

[0142] S400: the second slurry is aged in a reaction kettle, the pH value is controlled in the range of 1.6±0.15 during the aging process, the stirring speed is 500r / min, the aging temperature is 100℃, the aging time is 2.5h, the manganese phosphate complex is decomplexed and homogeneously precipitated to make the manganese element doped into the iron phosphate, the color of the precipitate changes from yellow to blue-violet, and the aged slurry is obtained.

[0143] S500: The aged slurry is filtered by a plate press to obtain a second solid material, and the second solid material in the cavity of the plate press filter is washed with pure water until the conductivity of the washed water is less than or equal to 350 us / cm to obtain a second washed material, and the second washed material is removed from the plate press filter after a pressure relief and discharging process to obtain a second filter cake.

[0144] S600: The second filter cake is subjected to normal pressure drying treatment at a drying temperature of 100°C for 14h to obtain a dried material, and the dried material is calcined at a calcination temperature of 650°C for 2.5h to obtain an iron phosphate material.

[0145] Example 4 This example is the same as or similar to example 1, except that: S100: Ferrous sulfate, pure water are weighed to prepare a ferrous sulfate solution (ferrous solution) with a concentration of 1 mol / L, a phosphorus salt (first phosphorus source, a phosphorus salt solution obtained by mixing ammonium dihydrogen phosphate solution and ammonia water, with a pH value of 7.0), pure water, hydrogen peroxide (first oxidizing agent, hydrogen peroxide mass fraction of 27%) are weighed to prepare a 5% (phosphorus element mass fraction) phosphorus salt solution (first solution), and the phosphorus salt solution is added dropwise into the ferrous sulfate solution under stirring at a first mixing temperature of 40°C and a rotation speed of 500 r / min for a first mixing time of 20 min, and then the mixture is stirred at a rotation speed of 500 r / min at a first reaction temperature of 55°C for a first reaction time of 50 min to obtain a first slurry with amorphous iron phosphate.

[0146] Example 5 This example is the same as or similar to example 1, except that: S100: Ferrous sulfate, pure water are weighed to prepare a ferrous sulfate solution (ferrous solution) with a concentration of 1 mol / L, a phosphorus salt (first phosphorus source, a phosphorus salt solution obtained by mixing ammonium dihydrogen phosphate solution and ammonia water, with a pH value of 7.0), pure water, hydrogen peroxide (first oxidizing agent, hydrogen peroxide mass fraction of 27%) are weighed to prepare a 5% (phosphorus element mass fraction) phosphorus salt solution (first solution), and the phosphorus salt solution is added dropwise into the ferrous sulfate solution under stirring at a first mixing temperature of 40°C and a rotation speed of 500 r / min for a first mixing time of 20 min, and then the mixture is stirred at a rotation speed of 500 r / min at a first reaction temperature of 55°C for a first reaction time of 50 min to obtain a first slurry with amorphous iron phosphate.

[0147] Example 6 This example is the same as or similar to example 1, except that: S100: ferrous sulfate, pure water to prepare a 1 mol / L concentration of ferrous sulfate solution (ferrous solution), phosphorus salt (first phosphorus source, phosphorus salt solution obtained by mixing ammonium dihydrogen phosphate solution and ammonia water, pH value is 7.0), pure water, hydrogen peroxide (first oxidizing agent, hydrogen peroxide mass fraction is 27%) to prepare a 5% (phosphorus element mass fraction) phosphorus salt solution (first solution), the molar ratio of ferrous sulfate: phosphorus salt: hydrogen peroxide is 1:1.00:0.5, the phosphorus salt solution is added dropwise into the ferrous sulfate solution under the stirring condition of 40℃ first mixing temperature and 500r / min rotating speed within 20min first mixing time, and the first slurry with amorphous ferric phosphate is obtained under the stirring condition of 500r / min rotating speed, 55℃ first reaction temperature and 50min first reaction time.

[0148] Example 7 This example is the same as or similar to example 1, except that: S100: ferrous sulfate, pure water to prepare a 1 mol / L concentration of ferrous sulfate solution (ferrous solution), phosphorus salt (first phosphorus source, phosphorus salt solution obtained by mixing ammonium dihydrogen phosphate solution and ammonia water, pH value is 7.0), pure water, hydrogen peroxide (first oxidizing agent, hydrogen peroxide mass fraction is 27%) to prepare a 5% (phosphorus element mass fraction) phosphorus salt solution (first solution), the molar ratio of ferrous sulfate: phosphorus salt: hydrogen peroxide is 1:1.00:0.5, the phosphorus salt solution is added dropwise into the ferrous sulfate solution under the stirring condition of 40℃ first mixing temperature and 500r / min rotating speed within 20min first mixing time, and the first slurry with amorphous ferric phosphate is obtained under the stirring condition of 500r / min rotating speed, 55℃ first reaction temperature and 50min first reaction time.

[0149] Example 8 This example is the same as or similar to example 1, except that: S300: the manganese source is manganese sulfate, the second oxidizing agent is potassium permanganate, the second phosphorus source is phosphoric acid, the molar ratio of the iron element in the ferrous solution used in step S100 to the manganese element in the manganese source is 0.9:0.1, the molar ratio of the iron element in the ferrous solution used in step S100 to the phosphorus element in the second phosphorus source is 1:0.15, the manganese source and the second phosphorus source are weighed and stirred to dissolve in pure water to obtain a second solution, the second solution and the first filter cake are mixed at a second mixing temperature of 25°C and a stirring speed of 1000r / min for a second mixing time of 10min to obtain a second mixture; the second oxidizing agent is weighed according to the molar ratio of the manganese element in the manganese source to the second oxidizing agent being 4:1.02, the stirring speed is kept unchanged, the second mixture and the second oxidizing agent are mixed at a third mixing temperature of 25°C for a third mixing time of 20min to obtain a third mixture, the pH value of the phosphoric acid control system is controlled within the range of 1.6±0.15, and the third mixture is dispersed at a dispersion temperature of 25°C for a dispersion time of 20min to obtain a second slurry.

[0150] Example 9 This example is the same as or similar to example 1, except that: S300: the manganese source is manganese sulfate, the second oxidizing agent is potassium permanganate, the second phosphorus source is phosphoric acid, the molar ratio of the iron element in the ferrous solution used in step S100 to the manganese element in the manganese source is 0.9:0.1, the molar ratio of the iron element in the ferrous solution used in step S100 to the phosphorus element in the second phosphorus source is 1:0.25, the manganese source and the second phosphorus source are weighed and stirred to dissolve in pure water to obtain a second solution, the second solution and the first filter cake are mixed at a second mixing temperature of 25°C and a stirring speed of 1000r / min for a second mixing time of 10min to obtain a second mixture; the second oxidizing agent is weighed according to the molar ratio of the manganese element in the manganese source to the second oxidizing agent being 4:1.2, the stirring speed is kept unchanged, the second mixture and the second oxidizing agent are mixed at a third mixing temperature of 25°C for a third mixing time of 20min to obtain a third mixture, the pH value of the phosphoric acid control system is controlled within the range of 1.6±0.15, and the third mixture is dispersed at a dispersion temperature of 25°C for a dispersion time of 20min to obtain a second slurry.

[0151] Example 10 This example is the same as or similar to example 1, except that: S300: the manganese source is manganese sulfate, the second oxidizing agent is potassium permanganate, the second phosphorus source is phosphoric acid, the molar ratio of the iron element in the ferrous solution used in step S100 to the manganese element in the manganese source is 0.9:0.1, the molar ratio of the iron element in the ferrous solution used in step S100 to the phosphorus element in the second phosphorus source is 1:0.1, the manganese source and the second phosphorus source are weighed and stirred to dissolve in pure water to obtain a second solution, the second solution and the first filter cake are mixed at a second mixing temperature of 25°C and a stirring speed of 1000r / min for a second mixing time of 10min to obtain a second mixture; the second oxidizing agent is weighed according to the molar ratio of the manganese element in the manganese source to the second oxidizing agent being 4:0.9, the stirring speed is kept unchanged, the second mixture and the second oxidizing agent are mixed at a third mixing temperature of 25°C for a third mixing time of 20min to obtain a third mixture, the pH value of the phosphoric acid control system is controlled within the range of 1.6±0.15, and the third mixture is dispersed at a dispersion temperature of 25°C for a dispersion time of 20min to obtain a second slurry.

[0152] Example 11 This example is the same as or similar to example 1, except that: S300: the manganese source is manganese sulfate, the second oxidizing agent is potassium permanganate, the second phosphorus source is phosphoric acid, the molar ratio of the iron element in the ferrous solution used in step S100 to the manganese element in the manganese source is 0.9:0.1, the molar ratio of the iron element in the ferrous solution used in step S100 to the phosphorus element in the second phosphorus source is 1:0.3, the manganese source and the second phosphorus source are weighed and stirred to dissolve in pure water to obtain a second solution, the second solution and the first filter cake are mixed at a second mixing temperature of 25°C and a stirring speed of 1000r / min for a second mixing time of 10min to obtain a second mixture; the second oxidizing agent is weighed according to the molar ratio of the manganese element in the manganese source to the second oxidizing agent being 4:1.3, the stirring speed is kept unchanged, the second mixture and the second oxidizing agent are mixed at a third mixing temperature of 25°C for a third mixing time of 20min to obtain a third mixture, the pH value of the phosphoric acid control system is controlled within the range of 1.6±0.15, and the third mixture is dispersed at a dispersion temperature of 25°C for a dispersion time of 20min to obtain a second slurry.

[0153] Example 12 This example is the same as or similar to example 1, except that: S300: the manganese source is manganese sulfate, the second oxidizing agent is potassium permanganate, the second phosphorus source is phosphoric acid, the molar ratio of the iron element in the ferrous solution used in step S100 to the manganese element in the manganese source is 0.95:0.05, the molar ratio of the iron element in the ferrous solution used in step S100 to the phosphorus element in the second phosphorus source is 1:0.2, the manganese source and the second phosphorus source are weighed and dissolved in pure water to obtain a second solution, and the second solution is mixed with the first filter cake at a second mixing temperature of 25°C, a stirring speed of 1000r / min, and for a second mixing time of 10min to obtain a second mixture; the second oxidizing agent is weighed according to a molar ratio of the manganese element in the manganese source to the second oxidizing agent of 4:1.1, the stirring speed is kept unchanged, the second mixture is mixed with the second oxidizing agent at a third mixing temperature of 25°C for a third mixing time of 20min to obtain a third mixture, the pH value of the phosphoric acid control system is controlled within a range of 1.6±0.15, and the third mixture is dispersed at a dispersion temperature of 25°C for a dispersion time of 20min to obtain a second slurry.

[0154] Example 13 This example is the same as or similar to example 1, except that: S400: the second slurry is aged in a reaction kettle, the pH value is controlled within a range of 1.6±0.15 during the aging process, the aging temperature is 98°C, the aging time is 1h, the manganese phosphate complex is decomplexed and homogeneously precipitated to dope the manganese element into the ferric phosphate, the precipitate color changes from yellow to blue-violet, and an aged slurry is obtained.

[0155] Example 14 This example is the same as or similar to example 1, except that: S400: the second slurry is aged in a reaction kettle, the pH value is controlled within a range of 1.6±0.15 during the aging process, the aging temperature is 98°C, the aging time is 3h, the manganese phosphate complex is decomplexed and homogeneously precipitated to dope the manganese element into the ferric phosphate, the precipitate color changes from yellow to blue-violet, and an aged slurry is obtained.

[0156] Example 15 This example is the same as or similar to example 1, except that: S600: the second filter cake is subjected to normal pressure drying treatment, the drying temperature is 98°C, the drying time is 12h, and a dry material is obtained; the dry material is calcined at a calcination temperature of 550°C for a calcination time of 1h to obtain a ferric phosphate material.

[0157] Example 16 This example is the same as or similar to example 1, except that: S600: The second filter cake is subjected to atmospheric drying treatment, the drying temperature is 98℃, the drying time is 12h, and a dry material is obtained; the dry material is calcined at a calcination temperature of 700℃ for 3h, and a ferric phosphate material is obtained.

[0158] Example 17 This example is the same as or similar to example 1, except that: Step S300: The manganese source is manganese sulfate, the second oxidizing agent is ammonium persulfate, the catalyst is silver nitrate, and the second phosphorus source is phosphoric acid. The molar ratio of iron elements in the ferrous solution used in step S100 to manganese elements in the manganese source is 0.9:0.1, and the molar ratio of iron elements in the ferrous solution used in step S100 to phosphorus elements in the second phosphorus source is 1:0.2. The manganese source and the second phosphorus source are weighed and stirred to dissolve in pure water as a second solution. The second solution and the first filter cake are mixed at a second mixing temperature of 25℃ and a stirring speed of 1000r / min for a second mixing time of 10min to obtain a second mixture. The second oxidizing agent and the catalyst are weighed according to a molar ratio of manganese elements in the manganese source to the second oxidizing agent and the catalyst of 6:5.1:0.2, and the stirring speed is maintained unchanged. The second mixture and the second oxidizing agent are mixed at a third mixing temperature of 25℃ for a third mixing time of 20min to obtain a third mixture. The pH value of the phosphoric acid control system is in the range of 1.6±0.15. The third mixture is dispersed at a dispersion temperature of 25℃ for a dispersion time of 20min to obtain a second slurry.

[0159] Example 18 This example is the same as or similar to example 18, except that: Step S300: The manganese source is manganese sulfate, the second oxidizing agent is ammonium persulfate, the catalyst is silver nitrate, and the second phosphorus source is phosphoric acid. The molar ratio of iron elements in the ferrous solution used in step S100 to manganese elements in the manganese source is 0.9:0.1, and the molar ratio of iron elements in the ferrous solution used in step S100 to phosphorus elements in the second phosphorus source is 1:0.2. The manganese source and the second phosphorus source are weighed and stirred to dissolve in pure water as a second solution. The second solution and the first filter cake are mixed at a second mixing temperature of 25℃ and a stirring speed of 1000r / min for a second mixing time of 10min to obtain a second mixture. The second oxidizing agent and the catalyst are weighed according to a molar ratio of manganese elements in the manganese source to the second oxidizing agent and the catalyst of 6:5.1:0.2, and the stirring speed is maintained unchanged. The second mixture and the second oxidizing agent are mixed at a third mixing temperature of 25℃ for a third mixing time of 20min to obtain a third mixture. The pH value of the phosphoric acid control system is in the range of 1.6±0.15. The third mixture is dispersed at a dispersion temperature of 25℃ for a dispersion time of 20min to obtain a second slurry.

[0160] Example 19 This example is the same as or similar to Example 18, except that: Step S300: the manganese source is manganese sulfate, the second oxidizing agent is ammonium persulfate, the catalyst is silver nitrate, and the second phosphorus source is phosphoric acid. The molar ratio of the iron element in the ferrous solution used in step S100 to the manganese element in the manganese source is 0.9:0.1, and the molar ratio of the iron element in the ferrous solution used in step S100 to the phosphorus element in the second phosphorus source is 1:0.2. The manganese source and the second phosphorus source are weighed and dissolved in pure water to prepare a second solution. The second solution is mixed with the first filter cake at a second mixing temperature of 25°C and a stirring speed of 1000 r / min for a second mixing time of 10 min to obtain a second mixture. The molar ratio of the manganese element in the manganese source to the second oxidizing agent and the catalyst is 6:5.2:0.22. The second mixture is mixed with the second oxidizing agent at a third mixing temperature of 25°C for a third mixing time of 20 min to obtain a third mixture. The pH value of the phosphoric acid control system is controlled within the range of 1.6±0.15. The third mixture is dispersed at a dispersion temperature of 25°C for a dispersion time of 20 min to obtain a second slurry.

[0161] Comparative Example 1 1. Synthesis of 8-water ferrous phosphate: ferrous sulfate solution and pure water are weighed and prepared into a 1 mol / L ferrous sulfate solution. Manganese sulfate and phosphoric acid are added to the phosphorus iron solution in a molar ratio of manganese: iron: phosphorus = 0.02: 0.98: 0.7. Ammonia water is added dropwise to adjust the pH value of the solution to 6.5 to obtain manganese-doped 8-water ferrous phosphate. The obtained 8-water manganese ferrous phosphate is filtered and rinsed to a conductivity of ≤3.5 ms / cm. 2. Oxidation and aging: the 8-water manganese ferrous phosphate washed with water is slurried and supplemented with phosphoric acid. Hydrogen peroxide is added dropwise for oxidation. The molar ratio of hydrogen peroxide to iron is 0.6:1. The slurry is heated to 98°C and aged for 2 h. The slurry is filtered and rinsed to a conductivity of ≤350 us / cm to obtain white manganese iron phosphate dihydrate. 3. Drying and calcination: the manganese iron phosphate dihydrate is dried at 98°C for 12 h and calcined at 600°C for 2 h after drying to obtain manganese iron phosphate.

[0162] Comparative Example 2 This example is the same as or similar to Example 1, except that: S300: the manganese source is manganese sulfate, the second oxidizing agent is potassium permanganate, and the second phosphorus source is phosphoric acid; the molar ratio of the iron element in the ferrous solution used in step S100 to the manganese element in the manganese source is 0.88:0.12, and the molar ratio of the iron element in the ferrous solution used in step S100 to the phosphorus element in the second phosphorus source is 1:0.2; the manganese source and the second phosphorus source are weighed and dissolved in pure water to prepare a second solution; the second solution and the first filter cake are mixed at a second mixing temperature of 25°C and a stirring speed of 1000r / min for a second mixing time of 10min to obtain a second mixture; the second oxidizing agent is weighed according to a molar ratio of the manganese element in the manganese source to the second oxidizing agent of 4:1.1, and the second mixture and the second oxidizing agent are mixed at a third mixing temperature of 25°C for a third mixing time of 20min to obtain a third mixture, which is dispersed at a dispersion temperature of 25°C for a dispersion time of 20min to obtain a second slurry.

[0163] II. Test method 1. The content of manganese element and iron element in the iron phosphate material is detected by oxidation-reduction titration, and other impurity elements are detected by inductively coupled plasma emission spectrometry.

[0164] 2. The crystallinity of the iron phosphate material is obtained by X-ray diffraction.

[0165] 3. Electrochemical performance test of the positive electrode material Preparation of the positive electrode material: (1) the iron phosphate material, lithium carbonate and glucose prepared in the examples and comparative examples are mixed according to a molar ratio of 1:1:0.05, and the mixture is ground and mixed uniformly, and the D50 particle size of the mixed material is 0.65μm; (2) the mixed material is dried by spray drying, the inlet air temperature is 250°C, and the outlet air temperature is 120°C, to obtain an iron lithium phosphate precursor; (3) the iron lithium phosphate precursor is calcined in a nitrogen atmosphere, the calcination temperature is 800°C, and the holding time is 12h, to obtain an iron lithium phosphate material, which is the positive electrode material.

[0166] Electrochemical performance test: The positive electrode material prepared by using the iron phosphate material prepared in the examples and comparative examples as raw material is mixed with conductive carbon black and PVDF binder according to a mass ratio of 90:5:5, coated on a 12μm thick aluminum foil, and then the electrode sheet is placed in an oven at 110°C for drying for 10h, the dried electrode sheet is punched into a 15mm diameter positive electrode disc, and the positive electrode disc is pressed to a density of 1.8g / cm 3Rolling, taking lithium sheet with 16 mm diameter as counter electrode, electrolyte being 1 mol / L LiPF6 dissolved in EC: EMC: DEC with volume ratio of 1:1:1, battery assembly was carried out in LG2400 / 1000TS glove box produced by WIGAS Purification Technology (Suzhou) Co., Ltd., and a button-type half battery was obtained, and rate performance test was carried out on the button-type half battery.

[0167] The battery performance test system (model: CT3002A) of Wuhan Blue Electric Technology Co., Ltd. was used for testing, the test temperature was 25℃ and-20℃, the voltage range was 2V~4.35V, and the test rate was 0.1C and 1C.

[0168] II. Analysis of test results of each embodiment and comparative example Table 1 Table 2 From the results of Table 1, it can be seen that the manganese-doped iron phosphate material obtained by the preparation method of the iron phosphate material provided in the application has a significantly higher purity than the manganese iron phosphate of Comparative Example 1, and the performance of the positive electrode material prepared accordingly is also significantly better than that of the positive electrode material prepared using the manganese iron phosphate of Comparative Example 1 as raw material. Specifically, from the data in Table 2, it can be seen that the positive electrode material prepared using the iron phosphate material provided in the application as raw material has a 0.1C discharge specific capacity at 25℃ and-20℃, and a discharge capacity retention rate at 0.1C rate at-20℃, which are both significantly higher than those of the positive electrode material prepared using the manganese iron phosphate of Comparative Example 1 as raw material.

[0169] From the results of Table 1, it can be seen that the preparation method of the iron phosphate material provided in the application, compared with Comparative Example 2, controls the amount-of-substance ratio of manganese element in the manganese source to iron element in the ferrous source, so that the content of manganese element in the obtained iron phosphate material is 5200ppm~18100ppm. By introducing manganese element, the electrochemical performance of the positive electrode material prepared using the iron phosphate material as raw material at room temperature and at low temperature is improved, and by controlling the amount of introduced manganese element, the decrease of discharge specific capacity caused by John-Teller effect is avoided.

[0170] From the results of Table 1, it can be seen that, compared with the molar ratio of iron in the ferrous solution, phosphorus in the first solution and the first oxidizing agent in the first solution being 1:1.00:0.5 in Example 6, the insufficient amount of the first oxidizing agent causes the iron ions to be unable to be completely precipitated, the iron-manganese ratio to decrease, and the manganese content to increase, resulting in incomplete utilization of raw materials, rising costs and difficulty in controlling the stability of the finished product. The preparation method of the iron phosphate material provided in the present application controls the molar ratio of iron in the ferrous solution, phosphorus in the first solution and the first oxidizing agent in the first solution to be 1:(1.01-1.03):(0.58-0.7), and the obtained iron phosphate material as a raw material is more conducive to reducing costs and stably preparing a positive electrode material with significantly improved normal temperature and low temperature discharge performance.

[0171] From the results of Table 1, it can be seen that, compared with the molar ratio of iron in the ferrous solution, phosphorus in the first solution and the first oxidizing agent in the first solution being 1:1.00:0.5 in Example 6, the insufficient amount of the first oxidizing agent causes the iron ions to be unable to be completely precipitated, the iron-manganese ratio to decrease, and the manganese content to increase, resulting in incomplete utilization of raw materials, rising costs and difficulty in controlling the stability of the finished product. The preparation method of the iron phosphate material provided in the present application controls the molar ratio of iron in the ferrous solution, phosphorus in the first solution and the first oxidizing agent in the first solution to be 1:(1.01-1.03):(0.58-0.7), and the obtained iron phosphate material as a raw material is more conducive to reducing costs and stably preparing a positive electrode material with significantly improved normal temperature and low temperature discharge performance.

[0172] From the results of Table 1, it can be seen that, compared with the molar ratio of iron in the ferrous solution, phosphorus in the first solution and the first oxidizing agent in the first solution being 1:1.00:0.5 in Example 6, the insufficient amount of the first oxidizing agent causes the iron ions to be unable to be completely precipitated, the iron-manganese ratio to decrease, and the manganese content to increase, resulting in incomplete utilization of raw materials, rising costs and difficulty in controlling the stability of the finished product. The preparation method of the iron phosphate material provided in the present application controls the molar ratio of iron in the ferrous solution, phosphorus in the first solution and the first oxidizing agent in the first solution to be 1:(1.01-1.03):(0.58-0.7), and the obtained iron phosphate material as a raw material is more conducive to reducing costs and stably preparing a positive electrode material with significantly improved normal temperature and low temperature discharge performance.

[0173] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and embodiments having substantially the same configuration and playing the same role and effect as the technical idea within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, within the scope of the main idea of the present application, various modifications that can be thought of by those skilled in the art, and other ways constructed by combining part of the elements in the embodiments are also included in the scope of the present application.

Claims

1. An iron phosphate material, characterized in that, The ratio of the sum of the amount of substance of manganese element and iron element to the amount of substance of phosphorus element in the iron phosphate material is (0.96-0.98):1, and the content of manganese element in the iron phosphate material is 5200 ppm-18100 ppm.

2. The iron phosphate material of claim 1, wherein, The content of sulfur element and other metal elements except manganese element and iron element in the iron phosphate material is less than or equal to 350 ppm; and / or, The ratio of the amount of substance of iron element to the amount of substance of phosphorus element in the iron phosphate material is 0.91-0.

96.

3. A method for producing a ferric phosphate material, characterized by, Comprise: The ferrous source, the first phosphorus source and the first oxidizing agent are subjected to first mixing treatment to obtain a first slurry; The first slurry is subjected to first purification treatment to obtain a first filter cake; The first filter cake, the manganese source, the second phosphorus source and the second oxidizing agent are subjected to second mixing treatment to obtain a second slurry; The second slurry is subjected to aging treatment to obtain an aged slurry; The aged slurry is subjected to second purification treatment to obtain a second filter cake; The second filter cake is subjected to calcination treatment to obtain an iron phosphate material; The first slurry comprises amorphous iron phosphate, and the second slurry comprises a manganese phosphate complex; the content of manganese element in the iron phosphate material is 5200 ppm-18100 ppm.

4. The method of producing a ferric phosphate material according to claim 3, characterized by, The ferrous source, the first phosphorus source and the first oxidizing agent are subjected to first mixing treatment to obtain a first slurry, comprising: A ferrous solution and a first solution are provided, the first solution comprising the first phosphorus source and the first oxidizing agent; The first solution is mixed in the ferrous solution at a first mixing temperature for a first mixing time to obtain a first mixture; The first mixture is reacted at a first reaction temperature for a first reaction time to obtain the first slurry; The first mixing temperature is 38-42 DEG C, the first mixing time is 10-30 min, the first reaction temperature is 40-65 DEG C, and the first reaction time is 40-60 min; The ratio of the amount of substance of iron element in the ferrous solution, the amount of substance of phosphorus element in the first solution and the amount of substance of the first oxidizing agent in the first solution is 1:(1.01-1.05):(0.58-0.7).

5. The method of producing an iron phosphate material according to claim 3, wherein The first filter cake, the manganese source, the second phosphorus source and the second oxidizing agent are subjected to second mixing treatment to obtain a second slurry, comprising: A second solution is provided, the second solution comprising the manganese source and the second phosphorus source; The second solution and the first filter cake are mixed at a second mixing temperature for a second mixing time to obtain a second mixture; The second mixture and the second oxidizing agent are mixed at a third mixing temperature for a third mixing time to obtain a third mixture; The third mixture is dispersed at a dispersion temperature for a dispersion time to obtain the second slurry; The second mixing temperature is 20-30 DEG C, the second mixing time is 8-12 min, the third mixing temperature is 20-30 DEG C, the third mixing time is 5-30 min, the dispersion temperature is 20-30 DEG C, and the dispersion time is 20-30 min; The molar ratio of manganese element in the manganese source to iron element in the ferrous source is greater than 0:1 and less than or equal to 0.1:0.9; The valence of manganese element in the manganese source is +2, and the molar amount of the second oxidizing agent is 1 times to 1.2 times of the theoretical value required for oxidizing the manganese element in the manganese source; The molar ratio of iron element in the ferrous source to phosphorus element in the second phosphorus source is 1:(0.15-0.3).

6. The method of producing an iron phosphate material according to claim 3, wherein The step of aging the second slurry to obtain an aged slurry comprises: The second slurry is aged at an aging temperature for an aging time to obtain an aged slurry. The aging temperature is 95-100°C, and the aging time is 1.5-2.5h.

7. The method of producing an iron phosphate material according to claim 3, wherein The step of calcining the second filter cake to obtain a ferric phosphate material comprises: The second filter cake is calcined at a calcining temperature for a calcining time to obtain a ferric phosphate material. The calcining temperature is 550-650°C, and the calcining time is 1.5-2.5h.

8. A positive electrode material, characterized by, The positive electrode material is prepared from the ferric phosphate material of any one of claims 1-2, or is prepared from the ferric phosphate material prepared by the method of any one of claims 3-7.

9. A positive electrode sheet characterized by comprising: The positive electrode material of claim 8 is included.

10. A secondary battery characterized by comprising: The positive electrode tab of claim 9 is included.

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