Preparation method of fusiform hydroxyl ferric ammonium phosphate and fusiform ferric phosphate

Abstract

The invention belongs to the field of electrode materials, and particularly relates to a preparation method of fusiform hydroxyl ferric ammonium phosphate and fusiform ferric phosphate. The preparation method of fusiform hydroxyl ammonium ferric phosphate provided by the invention comprises the following steps: a) dropwise adding a phosphorus source solution into an iron source solution, and then adjusting the pH value of a feed liquid to 1.9-3.0 through ammonia water to obtain a to-be-aged feed liquid; in the step a), a phosphorus source in the phosphorus source solution is ammonium dihydrogen phosphate and / or diammonium hydrogen phosphate, an iron source in the iron source solution is ferric ions, and the molar ratio of the phosphorus source solution metered by P to the iron source solution metered by Fe is 1: (0.7-0.95); b) aging, filtering, washing and drying the to-be-aged feed liquid to obtain the fusiform ammonium iron phosphate hydroxyl.The prepared ammonium iron phosphate hydroxylhas the advantages that primary particles are uniform and small, secondary particles are fusiform, and the morphology of iron phosphate obtained after the ammonium iron phosphate hydroxylis calcined can keep the morphology characteristics of the ammonium iron phosphate hydroxyl.

Description

Technical Field

[0001] This invention belongs to the field of electrode materials, and particularly relates to a method for preparing fusiform ferric ammonium hydroxyphosphate and fusiform ferric phosphate. Background Technology

[0002] With the continuous development of new energy batteries, lithium-ion batteries are being widely used in electric vehicles and energy storage batteries. Lithium iron phosphate (LFP) has gradually become a research hotspot for lithium-ion battery cathode materials due to its advantages such as structural stability, high safety, excellent cycle performance, abundant raw material resources, and low price.

[0003] The charging and discharging process of lithium iron phosphate (LFP) batteries involves lithium-ion insertion / extraction and migration. Shortening the lithium-ion migration distance is beneficial to improving the electrochemical performance of LFP batteries. The smaller the primary particles of iron phosphate, the better it is for preparing LFP batteries with high electrochemical performance. Meanwhile, regularly shaped spindle-shaped iron phosphate particles can be tightly packed, reducing interparticle voids and improving compaction density. Therefore, how to prepare spindle-shaped iron phosphate particles with small primary particles and good uniformity in secondary particle morphology, as well as the precursor—ammonium hydroxyphosphate—has become a research focus in this field. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a method for preparing fusiform ferric ammonium hydroxyphosphate and fusiform ferric phosphate. The preparation method provided by the present invention is simple and easy to implement, and the obtained ferric ammonium hydroxyphosphate and ferric phosphate have small primary particles and secondary particles with fusiform morphology and good morphological consistency.

[0005] This invention provides a method for preparing spindle-shaped ferric ammonium hydroxyphosphate, comprising the following steps:

[0006] a) Add the phosphorus source solution dropwise to the iron source solution, and then adjust the pH of the solution to 1.9~3.0 with ammonia water to obtain the solution to be aged;

[0007] In step a), the phosphorus source in the phosphorus source solution is ammonium dihydrogen phosphate and / or diammonium hydrogen phosphate, the iron source in the iron source solution is ferric ions, and the molar ratio of the phosphorus source solution (calculated as P) to the iron source solution (calculated as Fe) is 1:(0.7~0.95).

[0008] b) The aging solution is aged, filtered, washed and dried to obtain spindle-shaped ferric ammonium hydroxyphosphate.

[0009] Preferably, in step a), the iron source solution is an iron nitrate solution.

[0010] Preferably, in step a), the content of ferric ions in the iron source solution is 0.7~1.5 mol / L.

[0011] Preferably, in step a), the total content of ammonium dihydrogen phosphate and diammonium hydrogen phosphate in the phosphorus source solution is 0.7~1.5 mol / L.

[0012] Preferably, in step a), the concentration of the ammonia water is 15~25wt%.

[0013] Preferably, in step b), the aging temperature is 90~95℃.

[0014] Preferably, in step b), the aging time is 2 to 4 hours.

[0015] This invention provides a method for preparing spindle-shaped iron phosphate, comprising the following steps:

[0016] Spindle-shaped ferric ammonium hydroxyphosphate was prepared according to the preparation method described in the above technical solution;

[0017] The spindle-shaped ferric ammonium hydroxyphosphate was calcined to obtain spindle-shaped ferric phosphate.

[0018] Preferably, the calcination temperature is 550~620℃.

[0019] Preferably, the calcination time is 2 to 4 hours.

[0020] Compared with existing technologies, this invention provides a method for preparing fusiform ferric ammonium hydroxyphosphate and fusiform iron phosphate. The method for preparing fusiform ferric ammonium hydroxyphosphate includes the following steps: a) adding a phosphorus source solution dropwise to an iron source solution, and then adjusting the pH of the solution to 1.9-3.0 with ammonia water to obtain a solution to be aged; in step a), the phosphorus source in the phosphorus source solution is ammonium dihydrogen phosphate and / or diammonium hydrogen phosphate, the iron source in the iron source solution is ferric ions, and the molar ratio of the phosphorus source solution (calculated as P) to the iron source solution (calculated as Fe) is 1:(0.7-0.95); b) aging, filtering, washing, and drying the solution to obtain fusiform ferric ammonium hydroxyphosphate. This invention uses ferric ions as the iron source and ammonium dihydrogen phosphate and diammonium hydrogen phosphate as the phosphorus source, and achieves morphological control of ferric ammonium hydroxyphosphate by adjusting the feed ratio (nFe / P) and the pH of the solution. The ferric ammonium hydroxyphosphate prepared by this invention has the characteristics of uniform and small primary particles and spindle-shaped secondary particles. Furthermore, the morphology of the iron phosphate obtained after calcination of this ferric ammonium hydroxyphosphate can retain the morphological characteristics of the ferric ammonium hydroxyphosphate, which is beneficial for the preparation of lithium iron phosphate with high electrochemical performance. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0022] Figure 1 This is a SEM image of the nano-sized ferric ammonium hydroxyphosphate provided in Example 1 of this invention;

[0023] Figure 2 This is the XRD pattern of the nano-hydroxyammonium phosphate provided in Example 1 of the present invention;

[0024] Figure 3 This is a SEM image of nano-hydroxyammonium phosphate provided in Example 2 of the present invention;

[0025] Figure 4 This is the XRD pattern of nano-hydroxyammonium phosphate provided in Example 2 of the present invention;

[0026] Figure 5 This is a SEM image of nano-hydroxyammonium phosphate provided in Example 3 of the present invention;

[0027] Figure 6 This is the XRD pattern of nano-hydroxyammonium phosphate provided in Example 3 of the present invention;

[0028] Figure 7 This is the XRD pattern of anhydrous ferric phosphate provided in Embodiment 3 of the present invention;

[0029] Figure 8 This is a SEM image of anhydrous ferric phosphate provided in Example 4 of the present invention;

[0030] Figure 9 This is the XRD pattern of anhydrous ferric phosphate provided in Embodiment 4 of the present invention;

[0031] Figure 10 This is a SEM image of nano-hydroxyammonium phosphate provided in Comparative Example 1 of this invention;

[0032] Figure 11 This is the XRD pattern of nano-hydroxyammonium phosphate provided in Comparative Example 1 of the present invention;

[0033] Figure 12 This is a SEM image of nano-hydroxyammonium phosphate provided in Comparative Example 3 of this invention;

[0034] Figure 13 This is the XRD pattern of nano-hydroxyferric ammonium phosphate provided in Comparative Example 3 of this invention. Detailed Implementation

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] This invention provides a method for preparing spindle-shaped ferric ammonium hydroxyphosphate, comprising the following steps:

[0037] a) Add the phosphorus source solution dropwise to the iron source solution, and then adjust the pH of the solution to 1.9~3.0 with ammonia water to obtain the solution to be aged;

[0038] b) The aging solution is aged, filtered, washed and dried to obtain spindle-shaped ferric ammonium hydroxyphosphate.

[0039] In the spindle-shaped ferric ammonium hydroxyphosphate method provided by the present invention, in step a), the iron source in the iron source solution is ferric ions, and the solvent is water; the iron source solution is preferably ferric nitrate solution; the content of ferric ions in the iron source solution is preferably 0.7~1.5 mol / L, specifically 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L or 1.5 mol / L, and most preferably 1 mol / L.

[0040] In the spindle-shaped ferric ammonium phosphate method provided by the present invention, in step a), the phosphorus source in the phosphorus source solution is ammonium dihydrogen phosphate and / or diammonium hydrogen phosphate, and the solvent is water; the total content of ammonium dihydrogen phosphate and diammonium hydrogen phosphate in the phosphorus source solution is preferably 0.7~1.5 mol / L, specifically 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L or 1.5 mol / L, and most preferably 1 mol / L.

[0041] In the spindle-shaped ferric ammonium hydroxyphosphate method provided by the present invention, in step a), the molar ratio of the phosphorus source solution (calculated as P) to the iron source solution (calculated as Fe) is 1:(0.7~0.95), specifically 1:0.7, 1:0.75, 1:0.8, 1:0.85, 1:0.9 or 1:0.95.

[0042] In the spindle-shaped ferric ammonium hydroxyphosphate method provided by the present invention, in step a), the dropwise addition is preferably carried out under stirring conditions; the stirring speed is preferably 200~800 rpm, specifically 200 rpm, 300 rpm, 400 rpm, 500 rpm, 600 rpm, 700 rpm or 800 rpm.

[0043] In the spindle-shaped ferric ammonium hydroxyphosphate method provided by the present invention, in step a), the concentration of the ammonia water is preferably 15-25 wt%, specifically 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, or 25 wt%.

[0044] In the spindle-shaped ferric ammonium hydroxyphosphate method provided by the present invention, in step b), the aging temperature is preferably 90~95℃, specifically 90℃, 91℃, 92℃, 93℃, 94℃ or 95℃; the aging time is preferably 2~4h, specifically 2h, 2.5h, 3h, 3.5h or 4h.

[0045] This invention also provides a method for preparing spindle-shaped iron phosphate, comprising the following steps:

[0046] The spindle-shaped ferric ammonium hydroxyphosphate was prepared according to the preparation method described in the above technical solution;

[0047] The spindle-shaped ferric ammonium hydroxyphosphate was calcined to obtain spindle-shaped ferric phosphate.

[0048] In the method for preparing spindle-shaped iron phosphate provided by the present invention, the calcination temperature is preferably 550~620℃, specifically 550℃, 560℃, 570℃, 580℃, 590℃, 600℃, 610℃ or 620℃; the calcination time is preferably 2~4h, specifically 2h, 2.5h, 3h, 3.5h or 4h.

[0049] The technical solution provided by this invention uses trivalent iron as the iron source and ammonium dihydrogen phosphate and diammonium hydrogen phosphate as the phosphorus sources. By adjusting the feed ratio (nFe / P) and the pH value of the feed solution, the morphology of ferric ammonium hydroxyphosphate is controlled. The ferric ammonium hydroxyphosphate prepared by this invention has the characteristics of uniform and small primary particles and spindle-shaped secondary particles. Furthermore, the morphology of the iron phosphate obtained after calcination of this ferric ammonium hydroxyphosphate can maintain the morphological characteristics of ferric ammonium hydroxyphosphate, which is beneficial for the preparation of lithium iron phosphate with high electrochemical performance.

[0050] For clarity, the following examples and comparative models will be used to provide a detailed description.

[0051] Example 1

[0052] (1) Use ferric nitrate nonahydrate to prepare a 1 mol / L aqueous solution as the iron source solution;

[0053] (2) Use diammonium hydrogen phosphate to prepare a 1 mol / L aqueous solution as the phosphorus source solution;

[0054] (3) Take 300g of iron source solution and measure the phosphorus source solution according to nFe / P=0.95. Add the phosphorus source solution dropwise to the iron source solution at room temperature. During this period, the iron source solution is stirred by a constant speed electric stirrer at a speed of 400rpm.

[0055] (4) Use 25.0g of ammonia solution with a mass fraction of 20% to adjust the pH of the above solution to 1.93 to obtain solution (a);

[0056] (5) Heat the liquid (a) to 90~94℃, age it for 4 hours, and then filter it to obtain filter cake (b).

[0057] (6) The filter cake (b) was washed with pure water and filtered again to obtain the semi-finished product of ferric ammonium hydroxyphosphate (c).

[0058] (7) Dry the semi-finished product (c) of ferric ammonium hydroxyphosphate to remove free water, and obtain nano-ferric ammonium hydroxyphosphate with thick sheet structure;

[0059] (8) Place nano-hydroxyammonium phosphate in a muffle furnace and calcine at 560°C for 2 hours to obtain anhydrous iron phosphate.

[0060] The nano-sized ferric ammonium hydroxyphosphate prepared in this embodiment was observed by scanning electron microscopy (SEM), and the results are as follows: Figure 1 As shown. (Through) Figure 1 It can be seen that the formed nano-sized ferric ammonium hydroxyphosphate has a regular spindle-shaped morphology.

[0061] X-ray diffraction (XRD) analysis was performed on the nano-sized ferric ammonium hydroxyphosphate prepared in this embodiment, and the results are as follows: Figure 2 .pass Figure 2 It can be seen that the characteristic peaks of ferric ammonium hydroxyphosphate are obvious.

[0062] Example 2

[0063] (1) Use ferric nitrate nonahydrate to prepare a 1 mol / L aqueous solution as the iron source solution;

[0064] (2) Use ammonium dihydrogen phosphate to prepare a 1 mol / L aqueous solution as the phosphorus source solution;

[0065] (3) Take 300g of iron source solution and measure the phosphorus source solution according to nFe / P=0.95. Add the phosphorus source solution dropwise to the iron source solution at room temperature. During this period, the iron source solution is stirred by a constant speed electric stirrer at a speed of 400rpm.

[0066] (4) Use 55.6g of ammonia solution with a mass fraction of 20% to adjust the pH of the above solution to 2.07 to obtain solution (a);

[0067] (5) Heat the liquid (a) to 90~94℃, age it for 4 hours, and then filter it to obtain filter cake (b).

[0068] (6) The filter cake (b) was washed with pure water and filtered again to obtain the semi-finished product of ferric ammonium hydroxyphosphate (c).

[0069] (7) Dry the semi-finished product (c) of ferric ammonium hydroxyphosphate to remove free water, and obtain nano-ferric ammonium hydroxyphosphate with thick sheet structure;

[0070] (8) Place nano-hydroxyammonium phosphate in a muffle furnace and calcine at 560°C for 2 hours to obtain anhydrous iron phosphate.

[0071] The nano-sized ferric ammonium hydroxyphosphate prepared in this embodiment was observed by scanning electron microscopy (SEM), and the results are as follows: Figure 3 As shown. (Through) Figure 3 It can be seen that the formed nano-sized ferric ammonium hydroxyphosphate has a regular spindle-shaped morphology.

[0072] X-ray diffraction (XRD) analysis was performed on the nano-sized ferric ammonium hydroxyphosphate prepared in this embodiment, and the results are as follows: Figure 4 .pass Figure 4 It can be seen that the characteristic peaks of ferric ammonium hydroxyphosphate are obvious.

[0073] Example 3

[0074] (1) Use ferric nitrate nonahydrate to prepare a 1 mol / L aqueous solution as the iron source solution;

[0075] (2) Use diammonium hydrogen phosphate to prepare a 1 mol / L aqueous solution as the phosphorus source solution;

[0076] (3) Take 430 mL of iron source solution and measure the phosphorus source solution according to n Fe / P = 0.70. Add the phosphorus source solution dropwise to the iron source solution at room temperature. During this period, the iron source solution is stirred by a constant speed electric stirrer at 400 rpm.

[0077] (4) Use 15.6g of ammonia solution with a mass fraction of 25% to adjust the pH of the above solution to 2.23 to obtain solution (a);

[0078] (5) Heat the liquid (a) to 90~94℃, age it for 4 hours, and then filter it to obtain filter cake (b).

[0079] (6) The filter cake (b) was washed with pure water and filtered again to obtain the semi-finished product of ferric ammonium hydroxyphosphate (c).

[0080] (7) Dry the semi-finished product (c) of ferric ammonium hydroxyphosphate to remove free water, and obtain nano-ferric ammonium hydroxyphosphate with thick sheet structure;

[0081] (8) Place nano-hydroxyammonium phosphate in a muffle furnace and calcine at 580°C for 3 hours to obtain anhydrous iron phosphate.

[0082] The nano-sized ferric ammonium hydroxyphosphate prepared in this embodiment was observed by scanning electron microscopy (SEM), and the results are as follows: Figure 5 As shown. (Through) Figure 5 It can be seen that the formed nano-hydroxyammonium phosphate has a spindle-shaped morphology with obvious morphological characteristics.

[0083] X-ray diffraction (XRD) analysis was performed on the nano-sized ferric ammonium hydroxyphosphate prepared in this embodiment, and the results are as follows: Figure 6 .pass Figure 6 It can be seen that the sample has obvious characteristic peaks of ferric ammonium hydroxyphosphate and no other impurity peaks.

[0084] X-ray diffraction (XRD) analysis was performed on the anhydrous ferric phosphate prepared in this embodiment, and the results are as follows: Figure 7 .pass Figure 7 It can be seen that the sample is anhydrous ferric phosphate, with no other impurity characteristic peaks.

[0085] Example 4

[0086] (1) Use ferric nitrate nonahydrate to prepare a 1 mol / L aqueous solution as the iron source solution;

[0087] (2) Use diammonium hydrogen phosphate to prepare a 1 mol / L aqueous solution as the phosphorus source solution;

[0088] (3) Take 500g of iron source solution and measure the phosphorus source solution according to nFe / P=0.95. Add the phosphorus source solution dropwise to the iron source solution at room temperature. During this period, the iron source solution is stirred by a constant speed electric stirrer at a speed of 400rpm.

[0089] (4) The pH of the above solution was adjusted to 2.97 using 33.0g of ammonia solution with a mass fraction of 25% to obtain solution (a);

[0090] (5) Heat the liquid (a) to 90~94℃, age it for 4 hours, and then filter it to obtain filter cake (b).

[0091] (6) The filter cake (b) was washed with pure water and filtered again to obtain the semi-finished product of ferric ammonium hydroxyphosphate (c).

[0092] (7) Dry the semi-finished product (c) of ferric ammonium hydroxyphosphate to remove free water, and obtain nano-ferric ammonium hydroxyphosphate with thick sheet structure;

[0093] (8) Place nano-hydroxyammonium phosphate in a muffle furnace and calcine at 580°C for 3 hours to obtain anhydrous iron phosphate.

[0094] The anhydrous ferric phosphate prepared in this embodiment was observed by scanning electron microscopy (SEM), and the results are as follows: Figure 8 As shown. (Through) Figure 8 It can be seen that the particle morphology of anhydrous ferric phosphate after calcination basically inherits the spindle structure of ammonium ferric phosphate, which is conducive to maintaining the original performance characteristics.

[0095] X-ray diffraction (XRD) analysis was performed on the anhydrous ferric phosphate prepared in this embodiment, and the results are as follows: Figure 9 .pass Figure 9 It can be seen that the sample is anhydrous ferric phosphate, with no other impurity characteristic peaks.

[0096] Comparative Example 1

[0097] (1) Use ferric nitrate nonahydrate to prepare a 1 mol / L aqueous solution as the iron source solution;

[0098] (2) Use phosphoric acid to prepare a 1 mol / L aqueous solution as a phosphorus source solution;

[0099] (3) Take 250 mL of iron source solution and measure the phosphorus source solution according to n Fe / P = 0.95. Add the phosphorus source solution dropwise to the iron source solution at room temperature. During this period, the iron source solution is stirred by a constant speed electric stirrer at 400 rpm.

[0100] (4) The pH of the above solution was adjusted to 1.96 using 76.9g of a 20% ammonia solution to obtain solution (a);

[0101] (5) Heat the liquid (a) to 90~94℃, age it for 4 hours, and then filter it to obtain filter cake (b).

[0102] (6) The filter cake (b) was washed with pure water and filtered again to obtain ferric ammonium hydroxyphosphate semi-finished product (c).

[0103] (7) Dry the semi-finished product (c) of ferric ammonium hydroxyphosphate to remove free water, and obtain nano-ferric ammonium hydroxyphosphate with thick sheet structure;

[0104] (8) Place nano-hydroxyammonium phosphate in a muffle furnace and calcine at 580°C for 3 hours to obtain anhydrous iron phosphate.

[0105] The nano-sized ferric ammonium hydroxyphosphate prepared in this comparative example was observed by scanning electron microscopy (SEM), and the results are as follows: Figure 10 As shown. (Through) Figure 10 It can be seen that the sample did not form a regular spindle-shaped structure.

[0106] X-ray diffraction (XRD) analysis was performed on the nano-sized ferric ammonium hydroxyphosphate prepared in this comparative example, and the results are as follows: Figure 11 .pass Figure 11 It can be seen that the sample XRD analysis showed an amorphous structure, and ferric ammonium hydroxyphosphate was not formed.

[0107] Comparative Example 2

[0108] (1) Use ferric nitrate nonahydrate to prepare a 1 mol / L aqueous solution as the iron source solution;

[0109] (2) Use diammonium hydrogen phosphate to prepare a 1 mol / L aqueous solution as the phosphorus source solution;

[0110] (3) Take 500 mL of iron source solution and measure the phosphorus source solution according to n Fe / P = 1.30. Add the phosphorus source solution dropwise to the iron source solution at room temperature. During this period, the iron source solution is stirred by a constant speed electric stirrer at 400 rpm.

[0111] (4) Use 34.0g of ammonia solution with a mass fraction of 20% to adjust the pH of the above solution to 1.97 to obtain solution (a);

[0112] (5) Heat the liquid (a) to 90~94℃ and age it for 4 hours. No sediment is produced.

[0113] Comparative Example 3

[0114] (1) Use ferric nitrate nonahydrate to prepare a 1 mol / L aqueous solution as the iron source solution;

[0115] (2) Use diammonium hydrogen phosphate to prepare a 1 mol / L aqueous solution as the phosphorus source solution;

[0116] (3) Take 500g of iron source solution and measure the phosphorus source solution according to nFe / P=0.95. Add the phosphorus source solution dropwise to the iron source solution at room temperature. During this period, the iron source solution is stirred by a constant speed electric stirrer at a speed of 400rpm.

[0117] (4) The pH of the above solution was adjusted to 1.67 using 27.4g of ammonia solution with a mass fraction of 25% to obtain solution (a);

[0118] (5) Heat the liquid (a) to 90~94℃, age it for 4 hours, and then filter it to obtain filter cake (b).

[0119] (6) The filter cake (b) was washed with pure water and filtered again to obtain the semi-finished product of ferric ammonium hydroxyphosphate (c).

[0120] (7) Dry the semi-finished product (c) of ferric ammonium hydroxyphosphate to remove free water, and obtain nano-ferric ammonium hydroxyphosphate with thick sheet structure;

[0121] (8) Place nano-hydroxyammonium phosphate in a muffle furnace and calcine at 580°C for 3 hours to obtain anhydrous iron phosphate.

[0122] The nano-sized ferric ammonium hydroxyphosphate prepared in this comparative example was observed by scanning electron microscopy (SEM), and the results are as follows: Figure 12 As shown. (Through) Figure 12 It can be seen that the sample did not form a regular spindle-shaped structure.

[0123] X-ray diffraction (XRD) analysis was performed on the nano-sized ferric ammonium hydroxyphosphate prepared in this comparative example, and the results are as follows: Figure 13 .pass Figure 13 It can be seen that the sample XRD analysis showed an amorphous structure, and ferric ammonium hydroxyphosphate was not formed.

[0124] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A process for the preparation of a shuttle-shaped iron ammonium hydroxyphosphate, characterized in that, The method comprises the following steps: a) adding a phosphorus source solution into an iron source solution, and then adjusting the pH value of the solution to 1.9-3.0 by ammonia water to obtain a solution to be aged; In step a), the phosphorus source in the phosphorus source solution is ammonium dihydrogen phosphate and / or diammonium hydrogen phosphate, the iron source in the iron source solution is trivalent iron ion, and the molar ratio of the phosphorus source solution (in terms of P) to the iron source solution (in terms of Fe) is 1:(0.7-0.95); b) aging, filtering, washing and drying the solution to be aged to obtain the fusiform ammonium iron hydroxyphosphate.

2. The production method according to claim 1, characterized by, In step a), the iron source solution is a ferric nitrate solution.

3. The production method according to claim 1, characterized by, In step a), the content of the trivalent iron ion in the iron source solution is 0.7-1.5 mol / L.

4. The method of claim 1, wherein, In step a), the total content of the ammonium dihydrogen phosphate and the diammonium hydrogen phosphate in the phosphorus source solution is 0.7-1.5 mol / L.

5. The preparation method according to claim 1, characterized in that, In step a), the concentration of the ammonia water is 15-25 wt%.

6. The method of claim 1, wherein, In step b), the temperature of the aging is 90-95°C.

7. The preparation method according to claim 1, characterized in that, In step b), the time of the aging is 2-4 h.

8. A method for producing a shuttle-shaped iron phosphate, characterized by, The method comprises the following steps: The fusiform ammonium iron hydroxyphosphate is prepared by the preparation method according to any one of claims 1-7; The fusiform ammonium iron hydroxyphosphate is calcined to obtain fusiform iron phosphate.

9. The preparation method according to claim 8, characterized in that, The temperature of the calcining is 550-620°C.

10. The preparation method according to claim 8, characterized in that, The time of the calcining is 2-4 h.

Images