A process for preparing battery-grade manganese iron ammonium phosphate

Abstract

This invention discloses a process for preparing battery-grade ferric manganese phosphate, comprising the following steps: preparing a manganese dihydrogen phosphate solution, a ferrous dihydrogen phosphate solution, and a reaction base solution respectively; adding the manganese dihydrogen phosphate solution, the ferrous dihydrogen phosphate solution, ammonia water, a morphology modifier, and the reaction base solution into a reactor filled with an inert atmosphere for reaction to obtain a ferric manganese phosphate monohydrate slurry; subjecting the ferric manganese phosphate monohydrate slurry to pressure filtration and washing to obtain a ferric manganese phosphate monohydrate filter cake, mother liquor, and wash water; and drying the ferric manganese phosphate monohydrate filter cake to obtain battery-grade ferric manganese phosphate. This invention features a short process flow and allows for arbitrary control of the morphology of ferric manganese phosphate through the addition of a morphology modifier, with primary particle sizes at the nanometer level.

Description

Technical Field

[0001] This invention belongs to the field of ferric manganese phosphate preparation technology, and particularly relates to a battery-grade ferric manganese phosphate preparation process. Background Technology

[0002] Currently, the main iron sources for the mainstream lithium manganese iron phosphate precursor, ferric ammonium manganese phosphate, are ferrous sulfate, ferric nitrate, ferric acetate, and ferric chloride, while the main manganese sources are manganese sulfate, manganese nitrate, manganese acetate, and manganese chloride. However, using these anionic manganese and iron sources introduces a large number of impurities into the reaction system. To remove these impurities, large amounts of pure water are often required for washing, but the washing effect is often poor, and the product still contains a large number of anionic impurities. The lithium manganese iron phosphate material prepared using this method will also contain a large number of impurities, leading to cell safety issues and a decline in cycle performance and electrical performance. Moreover, the reaction mother liquor and washing solution contain a large number of impurities, requiring expensive environmental protection equipment and resources to treat the wastewater to meet environmental discharge requirements, which also increases the production cost of ferric ammonium manganese phosphate.

[0003] Patent CN202310794078.4 proposes a method for preparing a small-particle-size manganese iron ammonium phosphate precursor, using a mixed salt solution containing metallic manganese, iron, and an optional M source as the main raw material. However, impurities such as sulfate, titanium, and magnesium in the mother liquor are introduced into the product, requiring a large amount of washing water. Furthermore, the unstable impurity content in the wastewater leads to poor product stability, which is detrimental to the production of battery-grade manganese iron ammonium phosphate. In addition, because manganese and iron are both divalent, the primary particle morphology of manganese iron ammonium phosphate directly produced is mostly flake-like or blocky. This primary particle morphology is only suitable for the preparation of rate-type manganese iron ammonium phosphate, not for the production of high-pressure compact manganese iron ammonium phosphate, as the flake-like or blocky primary particle morphology is not conducive to the matching of different particle sizes in the manganese iron ammonium phosphate material, resulting in large packing gaps between the primary particles. Therefore, a morphology-adjustable manganese iron ammonium phosphate preparation process is needed.

[0004] In response to the current requirements of new energy battery cell companies for low impurity content in raw materials and the increasingly stringent environmental protection requirements of the country, there is an urgent need for a preparation process that is simple in process flow, has low impurity content in products, adjustable product morphology, low wastewater content, and is environmentally friendly. Summary of the Invention

[0005] To address the problems of existing technologies, the present invention aims to provide a battery-grade manganese iron ammonium phosphate preparation process, which solves the problems of complex preparation processes, large wastewater output, high product impurity content, and uncontrollable morphology.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A process for preparing battery-grade ferric ammonium manganese phosphate includes the following steps:

[0008] (1) Prepare manganese dihydrogen phosphate solution, ferrous dihydrogen phosphate solution and reaction base liquid respectively;

[0009] (2) Add manganese dihydrogen phosphate solution, ferrous dihydrogen phosphate solution, ammonia water, morphology modifier and reaction base liquid into a reaction vessel filled with an inert atmosphere to react and obtain manganese ferric ammonium phosphate monohydrate slurry;

[0010] (3) The manganese ferric ammonium phosphate monohydrate slurry was subjected to pressure filtration and washing to obtain manganese ferric ammonium phosphate monohydrate filter cake, mother liquor and wash water;

[0011] (4) Dry the filter cake of manganese ferric ammonium phosphate monohydrate to obtain battery-grade manganese ferric ammonium phosphate.

[0012] Preferably, in step (1), the manganese source and the phosphorus source are reacted under a nitrogen atmosphere to obtain the manganese dihydrogen phosphate solution; the iron source and the phosphorus source are reacted under a nitrogen atmosphere to obtain the ferrous dihydrogen phosphate solution; the manganese dihydrogen phosphate solution has a manganese mass fraction of 2-5%, and the ferrous dihydrogen phosphate solution has an iron mass fraction of 2-5%.

[0013] Preferably, the manganese source is one or more of electrolytic manganese flakes, high-purity manganese flakes, and manganese powder; the phosphorus source is wet-process phosphoric acid or thermal-process phosphoric acid with a mass fraction of 10-30%; and the iron source is one or more of high-purity iron blocks, primary reduced iron powder, and secondary reduced iron powder.

[0014] Preferably, the reaction substrate in step (1) is a manganese ferric ammonium phosphate monohydrate slurry with a solid content of 8-15%.

[0015] Preferably, in step (2), the ammonia water is industrial ammonia water with a mass fraction of 25-28%, and the morphology modifier is a polyamide-amine polymer.

[0016] Preferably, in step (2), a continuous injection method is used, and the flow rate mass ratio of manganese dihydrogen phosphate solution and ferrous dihydrogen phosphate solution is controlled to be 1-3:0.5-1.5, and the sum of the mass flow rates of manganese dihydrogen phosphate solution and ferrous dihydrogen phosphate solution is compared with the mass flow rate of the morphology regulator to be 1:0.01-0.05.

[0017] Preferably, the pH value of the reaction in step (2) is 3 to 7, the reaction temperature is 50 to 90°C, and the reaction time is 2 to 8 hours.

[0018] Preferably, in step (3), pure water is used for washing, and the washing ratio of manganese ferric ammonium phosphate monohydrate to pure water is 1:1 to 5, and the washing is carried out until the conductivity of the washing water is ≤400us / cm.

[0019] Preferably, the drying equipment in step (4) is a vacuum microwave dryer with a drying temperature of 30 to 200°C and a vacuum degree of 0.01 to 0.1 MPa.

[0020] Preferably, the above process further includes adding phosphoric acid and ammonia to the mother liquor and washing water obtained in step (3) to adjust the pH to 3-7 and the degree of ammoniation to 1.00-1.20, and then evaporating and crystallizing to obtain battery-grade monoammonium phosphate.

[0021] The beneficial effects of this invention are:

[0022] The process of this invention is simple and the morphology of ferric manganese phosphate can be arbitrarily controlled by adding a morphology modifier, with the particle size at the nanometer level in a single step.

[0023] The raw materials of this invention are widely available, do not introduce other impurities, and have low impurity content in the product, meeting the requirements of battery-grade manganese iron ammonium phosphate. The process has no wastewater discharge and does not require additional wastewater treatment equipment, which greatly meets the needs of the industrial chain construction of phosphate chemical enterprises. Moreover, the mother liquor and washing liquid can be used as raw materials for the production of battery-grade monoammonium phosphate. By adding phosphoric acid and ammonia water to adjust the pH value and ammonification neutralization degree, and then evaporating and crystallizing, battery-grade monoammonium phosphate can be prepared, which greatly reduces the production cost. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly described below.

[0025] Figure 1 This is a process flow diagram of the preparation process of battery-grade iron ammonium manganese phosphate according to the present invention;

[0026] Figure 2 Here is a SEM image of the ferric ammonium manganese phosphate prepared in Example 1;

[0027] Figure 3 Here is a SEM image of the ferric ammonium manganese phosphate prepared in Example 2;

[0028] Figure 4 This is a SEM image of the ferric ammonium manganese phosphate prepared in Example 3. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0030] Please see Figure 1 The battery-grade manganese iron ammonium phosphate preparation process provided by the present invention includes the following steps:

[0031] (1) A manganese dihydrogen phosphate solution is obtained by reacting a manganese source and a phosphorus source under a nitrogen atmosphere; a ferrous dihydrogen phosphate solution is obtained by reacting an iron source and a phosphorus source under a nitrogen atmosphere; the manganese mass fraction of the manganese dihydrogen phosphate solution is 2-5%, and the iron mass fraction of the ferrous dihydrogen phosphate solution is 2-5%. A ferrous ammonium manganese phosphate slurry with a solid content of 8-15% is dissolved in solid manganese phosphate monohydrate and used as the reaction substrate. Using ferrous ammonium manganese phosphate monohydrate slurry as the reaction substrate in this invention allows for better control of pH and particle morphology. If pure water is used, its high pH value leads to significant fluctuations in pH and particle morphology in the initial stage of the reaction, which is detrimental to pH and particle morphology control. Using other acidic solutions is also unfavorable for pH and particle morphology control.

[0032] (2) A continuous injection method was used, controlling the flow rate mass ratio of manganese dihydrogen phosphate solution and ferrous dihydrogen phosphate solution to be 1–3:0.5–1.5, and the sum of the flow rates of manganese dihydrogen phosphate solution and ferrous dihydrogen phosphate solution to the flow rate of the morphology modifier to be 1:0.01–0.05. Manganese dihydrogen phosphate solution, ferrous dihydrogen phosphate solution, ammonia, morphology modifier, and reaction substrate were added to a reactor filled with an inert atmosphere for reaction. The flow rate of ammonia was adjusted according to the pH of the reaction system. The reaction pH was 3–7, the reaction temperature was 50–90℃, and the reaction time was 2–8 h, yielding a manganese ferric ammonium phosphate monohydrate slurry.

[0033] The ammonia solution can be selected from industrial ammonia solution with a mass fraction of 25-28%, and the morphology modifier is a polyamide-amine polymer, such as, but not limited to, one or more of RGD-PEG-PAMAM RGD, mPEG-PAMAM-G3, and PAMAM-PO3H2.

[0034] (3) The ammonium manganese phosphate monohydrate slurry is subjected to pressure filtration and washing with pure water until the conductivity of the washing water is ≤400us / cm, to obtain ammonium manganese phosphate monohydrate filter cake, mother liquor and washing water; the pressure filtration device can be selected from one of vertical filter press, horizontal filter press or horizontal sedimentation centrifuge, and the washing ratio of ammonium manganese phosphate monohydrate to pure water is 1:1 to 5.

[0035] (4) The filter cake of manganese ferric ammonium phosphate monohydrate was dried in a vacuum microwave dryer at a temperature of 30–200 °C and a vacuum degree of 0.01–0.1 MPa to obtain battery-grade manganese ferric ammonium phosphate NH4Mn with different morphologies. X Fe (1-x) PO4·H2O, 0.4≤x≤0.8.

[0036] (5) Add phosphoric acid and ammonia to the mother liquor and washing water obtained in step (3) and adjust the pH to 3-7 and the degree of ammoniation to 1.00-1.20. Then, evaporate and crystallize to obtain battery-grade monoammonium phosphate.

[0037] The reaction principle for preparing ferric ammonium manganese phosphate in this invention is as follows:

[0038] Fe + 2H₃PO₄ = Fe(H₂PO₄)₂ + H₂

[0039] Mn + 2H3PO4 = Mn(H2PO4)2 + H2

[0040] (1-X)Fe(H2PO4)2+XMn(H2PO4)2+2NH3.H2O=NH4Mn X Fe (1-x) PO4·H2O + NH4H2PO4 + H2O

[0041] In some preferred embodiments, the manganese source in step (1) is one or more of electrolytic manganese flakes, high-purity manganese flakes, and manganese powder; the phosphorus source is wet phosphoric acid or thermal phosphoric acid with a mass fraction of 10-30%; and the iron source is one or more of high-purity iron blocks, primary reduced iron powder, and secondary reduced iron powder.

[0042] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below.

[0043] Example 1

[0044] (1) A manganese dihydrogen phosphate solution with a manganese content of 4.0% was prepared by reacting 4.2t of electrolytic manganese sheets and 96t of 20% wet-process phosphoric acid under a nitrogen atmosphere at a reaction temperature of 65℃ for 8h. A ferrous dihydrogen phosphate solution with an iron content of 4.0% was prepared by reacting 4.3t of high-purity iron blocks and 96t of 20% wet-process phosphoric acid under a nitrogen atmosphere at a reaction temperature of 75℃ for 10h. A manganese ferric ammonium monohydrate powder was dissolved in a monoammonium phosphate mother liquor with a pH of 4 to prepare a manganese ferric ammonium monohydrate slurry with a solid content of 10% as the reaction base liquid.

[0045] (2) The following solutions were continuously added to a reactor containing 4.0% manganese dihydrogen phosphate solution (7 t / h), 4.0% iron ferrous dihydrogen phosphate solution (3 t / h), and morphology modifier PAMAM-PO3H2 at a flow rate of 0.5 t / h. The flow rate of ammonia water was adjusted according to the reaction pH value. The reaction was carried out under a nitrogen atmosphere, with the reaction temperature controlled at 80℃ and the reaction pH value at 4.0. After 4 hours of reaction, the overflow continuously yielded the slurry of 4.0% manganese dihydrogen phosphate.

[0046] (3) The manganese ferric ammonium phosphate monohydrate slurry was washed with pure water at a washing ratio of 1:3 through a vertical filter press until the conductivity was 327 μS / cm. The slurry was then discharged to obtain manganese ferric ammonium phosphate monohydrate filter cake, mother liquor and wash water.

[0047] (4) The filter cake of manganese ferric ammonium phosphate monohydrate was dried by a vacuum microwave drying device at a drying temperature of 45℃ and a vacuum degree of 0.025MPa to obtain battery-grade NH4M. 0.7 Fe 0.3 PO4·H2O powder, from Figure 2 It can be seen that the primary particles of manganese iron ammonium phosphate prepared in this embodiment have a spherical shape and are nanoscale.

[0048] (5) After adding phosphoric acid and ammonia to the mother liquor and washing water obtained in step 3) and adjusting the pH to 4.3 and the degree of ammoniation to 1.1, the battery-grade monoammonium phosphate is obtained by evaporation and crystallization using a DTB crystallizer.

[0049] Example 2

[0050] (1) A manganese dihydrogen phosphate solution with a manganese content of 4.0% was prepared by reacting 4.2t of electrolytic manganese sheets and 96t of 20% wet-process phosphoric acid under a nitrogen atmosphere at a reaction temperature of 65℃ for 8h. A ferrous dihydrogen phosphate solution with an iron content of 4.0% was prepared by reacting 4.3t of high-purity iron blocks and 96t of 20% wet-process phosphoric acid under a nitrogen atmosphere at a reaction temperature of 75℃ for 10h. A manganese ferric ammonium monohydrate powder was dissolved in a monoammonium phosphate mother liquor with a pH of 4 to prepare a manganese ferric ammonium monohydrate slurry with a solid content of 10% as the reaction base liquid.

[0051] (2) The following solutions were continuously added to a reactor containing 4.0% manganese dihydrogen phosphate solution (7 t / h), 4.0% iron ferrous dihydrogen phosphate solution (3 t / h), and morphology modifier PAMAM-PO3H2 at a flow rate of 0.3 t / h. The flow rate of ammonia water was adjusted according to the reaction pH value. The reaction was carried out under a nitrogen atmosphere, with the reaction temperature controlled at 80℃ and the reaction pH value at 4.0. After 4 hours of reaction, the overflow continuously yielded the slurry of 4.0% manganese dihydrogen phosphate.

[0052] (3) The manganese ferric ammonium phosphate monohydrate slurry was washed with pure water at a washing ratio of 1:3 through a vertical filter press until the conductivity was 327 μS / cm. The slurry was then discharged to obtain manganese ferric ammonium phosphate monohydrate filter cake, mother liquor and wash water.

[0053] (4) The filter cake of manganese ferric ammonium phosphate monohydrate was dried by a vacuum microwave drying device at a drying temperature of 45℃ and a vacuum degree of 0.025MPa to obtain battery-grade NH4M. 0.7 Fe 0.3 PO4·H2O powder, from Figure 3 It can be seen that the primary particle morphology of the manganese iron ammonium phosphate prepared in this embodiment is lamellar and nanoscale.

[0054] (5) After adding phosphoric acid and ammonia to the mother liquor and washing water obtained in step 3) and adjusting the pH to 4.3 and the degree of ammoniation to 1.1, the battery-grade monoammonium phosphate is obtained by evaporation and crystallization using a DTB crystallizer.

[0055] Example 3

[0056] (1) A manganese dihydrogen phosphate solution with a manganese content of 4.0% was prepared by reacting 4.2t of electrolytic manganese sheets and 96t of 20% wet-process phosphoric acid under a nitrogen atmosphere at a reaction temperature of 65℃ for 8h. A ferrous dihydrogen phosphate solution with an iron content of 4.0% was prepared by reacting 4.3t of high-purity iron blocks and 96t of 20% wet-process phosphoric acid under a nitrogen atmosphere at a reaction temperature of 75℃ for 10h. A manganese ferric ammonium monohydrate powder was dissolved in a monoammonium phosphate mother liquor with a pH of 4 to prepare a manganese ferric ammonium monohydrate slurry with a solid content of 10% as the reaction base liquid.

[0057] (2) The following solutions were continuously added to a reactor containing 4.0% manganese dihydrogen phosphate solution (7 t / h), 4.0% iron ferrous dihydrogen phosphate solution (3 t / h), and morphology modifier PAMAM-PO3H2 at a flow rate of 0.1 t / h. The flow rate of ammonia water was adjusted according to the reaction pH value. The reaction was carried out under a nitrogen atmosphere, with the reaction temperature controlled at 80℃ and the reaction pH value at 4.0. After 4 hours of reaction, the overflow continuously yielded the slurry of 4.0% manganese dihydrogen phosphate.

[0058] (3) The manganese ferric ammonium phosphate monohydrate slurry was washed with pure water at a washing ratio of 1:3 through a vertical filter press until the conductivity was 327 μS / cm. The slurry was then discharged to obtain manganese ferric ammonium phosphate monohydrate filter cake, mother liquor and wash water.

[0059] (4) The filter cake of manganese ferric ammonium phosphate monohydrate was dried by a vacuum microwave drying device at a drying temperature of 45℃ and a vacuum degree of 0.025MPa to obtain battery-grade NH4M. 0.7 Fe 0.3 PO4·H2O powder, from Figure 4 It can be seen that the primary particle morphology of the manganese iron ammonium phosphate prepared in this embodiment is blocky and nanoscale.

[0060] (5) After adding phosphoric acid and ammonia to the mother liquor and washing water obtained in step 3) and adjusting the pH to 4.3 and the degree of ammoniation to 1.1, the battery-grade monoammonium phosphate is obtained by evaporation and crystallization using a DTB crystallizer.

[0061] Performance testing

[0062] Figures 2-4 The images shown are scanning electron microscope (SEM) images of the iron manganese phosphate prepared in Examples 1 to 3. It can be seen that the particle size of the products prepared by the method of the present invention is all in the nanometer range. Specifically, the particles in Example 1 are spherical, those in Example 2 are lamellar, and those in Example 3 are blocky. This shows that the morphology of the product can be controlled by adjusting the amount of morphology modifier added. As the amount added gradually increases, the morphology of iron manganese phosphate changes from blocky to lamellar, and then to spherical.

[0063] The content of impurity elements in the iron ammonium manganese phosphate products prepared in Examples 1-3 was tested, and the results are shown in Table 1.

[0064] Table 1

[0065]

[0066]

[0067] As can be seen from Table 1, the impurity content of the iron manganese phosphate prepared by the process of the present invention is low, which meets the requirements of battery-grade iron manganese phosphate.

[0068] In summary, this invention provides a continuous process for preparing battery-grade lithium manganese iron phosphate using a metallic manganese-iron method. The process involves preparing manganese dihydrogen phosphate solution and ferrous dihydrogen phosphate solution respectively under a nitrogen atmosphere using manganese and phosphorus sources, and iron and phosphorus sources. A slurry of ammonium manganese iron phosphate monohydrate is added to the reactor as a base solution. Ferrous dihydrogen phosphate, manganese dihydrogen phosphate solution, ammonia, and a morphology modifier are continuously heated and reacted in the reactor under a nitrogen atmosphere at a specific flow rate and ratio to prepare the ammonium manganese iron phosphate monohydrate slurry. This slurry is then filtered and washed to obtain an ammonium manganese iron phosphate monohydrate filter cake, which is dried to obtain ammonium manganese iron phosphate monohydrate powder. The process is short, and the continuous addition of the morphology modifier allows for morphology control of the ammonium manganese iron phosphate at the nanometer scale. Morphology adjustment can achieve block, lamellar, and spherical morphologies. The raw materials are widely available, do not introduce other impurities, and the product has low impurity content, meeting the requirements for preparing battery-grade lithium manganese iron phosphate. The process also produces no wastewater, greatly aligning with the supply chain development needs of phosphate chemical enterprises. For example, companies with the capacity to produce refined phosphoric acid and monoammonium phosphate can directly use refined phosphoric acid to produce manganese iron ammonium phosphate and monoammonium phosphate.

[0069] The process for preparing ferric manganese phosphate does not require additional wastewater treatment equipment and produces no wastewater. The mother liquor and wash water can be used as raw materials for the production of battery-grade monoammonium phosphate. Phosphoric acid and ammonia are added to adjust the pH value and the degree of ammoniation neutralization. After evaporation and crystallization, battery-grade monoammonium phosphate is prepared, which greatly reduces the production cost of ferric manganese phosphate.

[0070] It should be noted that all the above embodiments belong to the same inventive concept, and the descriptions of each embodiment have different focuses. Where the description in a particular embodiment is not detailed, please refer to the description in other embodiments.

[0071] The embodiments described above are merely illustrative of implementation methods of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A process for preparing battery-grade ferric ammonium manganese phosphate, characterized in that, Includes the following steps: (1) Prepare manganese dihydrogen phosphate solution, ferrous dihydrogen phosphate solution and reaction base liquid respectively; the reaction base liquid is manganese ferric ammonium monohydrate slurry with a solid content of 8~15%; (2) Add manganese dihydrogen phosphate solution, ferrous dihydrogen phosphate solution, ammonia water, morphology modifier and reaction base liquid to a reaction vessel filled with an inert atmosphere to react and obtain manganese iron ammonium phosphate monohydrate slurry; the morphology modifier is a polyamide-amine polymer; (3) The manganese ferric ammonium phosphate monohydrate slurry was subjected to pressure filtration and washing to obtain manganese ferric ammonium phosphate monohydrate filter cake, mother liquor and wash water; (4) Dry the filter cake of the monohydrate ferric manganese phosphate to obtain battery-grade ferric manganese phosphate.

2. The battery-grade ferric ammonium manganese phosphate preparation process according to claim 1, characterized in that, In step (1), manganese and phosphorus sources are reacted under a nitrogen atmosphere to prepare the manganese dihydrogen phosphate solution; iron and phosphorus sources are reacted under a nitrogen atmosphere to prepare ferrous dihydrogen phosphate solution; The manganese dihydrogen phosphate solution has a manganese mass fraction of 2-5%, and the ferrous dihydrogen phosphate solution has an iron mass fraction of 2-5%.

3. The battery-grade ferric ammonium manganese phosphate preparation process according to claim 2, characterized in that, The manganese source is one or more of electrolytic manganese flakes, high-purity manganese flakes, and manganese powder; the phosphorus source is wet-process phosphoric acid or thermal-process phosphoric acid with a mass fraction of 10-30%; and the iron source is one or more of high-purity iron blocks, primary reduced iron powder, and secondary reduced iron powder.

4. The battery-grade ferric ammonium manganese phosphate preparation process according to claim 1, characterized in that, The ammonia water mentioned in step (2) is industrial ammonia water with a mass fraction of 25-28%.

5. The battery-grade ferric ammonium manganese phosphate preparation process according to claim 1, characterized in that, In step (2), a continuous injection method is adopted, and the flow rate mass ratio of manganese dihydrogen phosphate solution and ferrous dihydrogen phosphate solution is controlled to be 1~3:0.5~1.

5. The sum of the mass flow rates of manganese dihydrogen phosphate solution and ferrous dihydrogen phosphate solution and the mass flow rate of morphology regulator are 1:0.01~0.

05.

6. The battery-grade ferric ammonium manganese phosphate preparation process according to claim 1, characterized in that, The pH value of the reaction in step (2) is 3~7, the reaction temperature is 50~90℃, and the reaction time is 2~8h.

7. The battery-grade ferric ammonium manganese phosphate preparation process according to claim 1, characterized in that, In step (3), pure water is used for washing. The washing ratio of the manganese iron ammonium phosphate monohydrate to pure water is 1:1~5, and the washing is carried out until the conductivity of the washing water is ≤400us / cm.

8. The battery-grade ferric ammonium manganese phosphate preparation process according to claim 1, characterized in that, The drying temperature in step (4) is 30~200℃ and the vacuum degree is 0.01~0.1MPa.

9. The battery-grade ferric ammonium manganese phosphate preparation process according to claim 1, characterized in that, It also includes adding phosphoric acid and ammonia to the mother liquor and washing water obtained in step (3) to adjust the pH to 3~7 and the degree of ammoniation to 1.00~1.20, and then evaporating and crystallizing to obtain battery-grade monoammonium phosphate.

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