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CN-121990539-A - Method for preparing ferric phosphate dihydrate with high tap density

CN121990539ACN 121990539 ACN121990539 ACN 121990539ACN-121990539-A

Abstract

A process for preparing high tap density ferric phosphate dihydrate is disclosed, comprising adding to a suspension containing ferric phosphate dihydrate particles an iron phosphate complex solution at a temperature of 50-130 ℃, the iron phosphate complex solution precipitating and forming a ferric phosphate dihydrate product during decomplexing, the product having a higher tap density than the raw ferric phosphate dihydrate particles. The ferric phosphate dihydrate prepared by the method has irregular polyhedron morphology, and the tap density is higher than 0.9g/cm 3 .

Inventors

  • MA XIAOLING
  • Luo Juanqun
  • CHEN RUI

Assignees

  • 黄冈林立新能源科技有限公司

Dates

Publication Date
20260508
Application Date
20241107

Claims (10)

  1. 1. A process for preparing iron phosphate dihydrate comprises adding an iron phosphate complex to a suspension containing iron phosphate dihydrate particles at a temperature of 50-130 ℃, the iron phosphate complex precipitating and forming an iron phosphate dihydrate product during decomplexing.
  2. 2. A method according to claim 1, wherein the temperature is 70-110 ℃, preferably 85-105 ℃.
  3. 3. The method of claim 1 or 2, wherein the iron phosphate dihydrate particles are nanoparticles, microparticles or larger particle size particles of iron phosphate dihydrate.
  4. 4. The method according to claim 1 to 3, wherein the suspension containing ferric phosphate dihydrate particles is obtained by mixing ferric phosphate dihydrate particles having a particle size of nanometer, micrometer or more with water or an aqueous solution containing phosphoric acid, or The suspension containing the ferric phosphate dihydrate particles is prepared in situ, and the in-situ preparation method comprises the steps of diluting an iron phosphate complex with water or an aqueous solution containing phosphoric acid at the temperature of between room temperature and 110 ℃, and decomplexing to separate out the ferric phosphate dihydrate particles.
  5. 5. The method of claim 4, wherein the aqueous solution comprising phosphoric acid comprises water, phosphoric acid, and/or an iron phosphate complex, wherein the weight ratio of phosphoric acid to iron phosphate complex is between 0.01% and 30% of the total weight, and wherein the phosphoric acid or iron phosphate complex is derived from the reuse of mother liquor after separation of product iron phosphate dihydrate solids.
  6. 6. The method according to any one of claims 1 to 5, wherein the rate of increase of the concentration of the iron phosphate complex is controlled within 0.001 mol/(l.min) to 0.05 mol/(l.min), preferably 0.005 mol/(l.min) to 0.04 mol/(l.min).
  7. 7. A method of preparing iron phosphate, comprising: S1, preparing a suspension containing ferric phosphate dihydrate particles; s2, adding an iron phosphate complex solution into the suspension of the S1 at 50-130 ℃, and after the addition is completed, preserving heat and aging; s3, solid-liquid separation is carried out to obtain ferric phosphate dihydrate solid, and high-temperature dehydration is carried out to obtain ferric phosphate products; Wherein the volume of the liquid in the suspension in S1 is not less than the volume of the ferric phosphate complex liquid added in S2, and preferably V Suspension liquid ：V Complexing liquid is 1:1-10:1.
  8. 8. The method of claim 7, wherein in the step S1, the ferric phosphate dihydrate solid particles are added into water or a phosphoric acid-containing water solution to form a suspension or are prepared in situ to obtain the ferric phosphate dihydrate suspension, in the step S2, the temperature is 70-110 ℃, after the solid-liquid separation in the step S3, the separated mother liquor is reused for replacing or partially replacing the water or the phosphoric acid-containing water solution in the step S1, the suspension in the step S1 is prepared, and the high-temperature dehydration temperature is 400-1000 ℃.
  9. 9. The method of claim 8, wherein the in situ preparation of the ferric phosphate dihydrate suspension in step S1 comprises diluting the ferric phosphate complex with water or an aqueous solution containing phosphoric acid at a temperature of from room temperature to 110 ℃, decomplexing to precipitate ferric phosphate dihydrate particles, wherein the temperature is from 85 ℃ to 105 ℃ in step S2, and wherein the high temperature dehydration in step S3 is from 500 ℃ to 800 ℃.
  10. 10. An iron phosphate material characterized by having a random polyhedral morphology of stacked micron secondary particles having tap density greater than 0.9g/cm 3 , preferably tap density from 0.95 to 1.4g/cm 3 , prepared by the method of any one of claims 1 to 9.

Description

Method for preparing ferric phosphate dihydrate with high tap density Technical Field The invention belongs to the technical field of inorganic materials and lithium battery materials, and particularly relates to a preparation method of a precursor material ferric phosphate of a lithium ion battery. Background Lithium ion battery materials develop rapidly, especially lithium iron phosphate and ternary materials. Based on the requirement for the energy density improvement of the lithium iron phosphate battery, the compaction density of the lithium iron phosphate can be increased to serve as one way for increasing the energy density of the lithium iron phosphate battery. The iron phosphate serving as a raw material for preparing the lithium iron phosphate has direct influence on the compaction density of the lithium iron phosphate, and the energy density of the lithium iron phosphate battery pack can be finally improved by preparing the high-purity high-compaction iron phosphate. The main methods for preparing the high-compaction ferric phosphate products at present are as follows: CN115215313A generates an amorphous ferrous phosphate octahydrate reaction precursor in situ in a first mixture system by controlling synthesis conditions, controls the dissolution rate of the amorphous ferrous phosphate octahydrate reaction precursor by controlling the pH of a second slurry, further regulates and controls the concentration of phosphate radical and ferrous ion in a reaction system, and then realizes the accurate regulation and control of the supersaturation degree of iron ion and phosphate radical ion in the reaction system by adding oxidizing substances. The method for preparing high-compaction ferric phosphate from industrial monoammonium phosphate and ferrous sulfate provided by CN116534820B adopts a reaction route of firstly oxidizing and then double decomposing, firstly using hydrogen peroxide to completely oxidize a refined ferrous sulfate solution, then slowly adding monoammonium phosphate, and enabling the initial iron element concentration of the reaction solution to be high, so that a small amount of added monoammonium phosphate and high-concentration iron ions can quickly react to form small-particle ferric phosphate, and in the subsequent reaction, the small-particle ferric phosphate is taken as a core to aggregate and grow, so that the reaction is thorough. Increasing the tap density of the iron phosphate precursor is one of the common methods for increasing the compacted density of lithium iron phosphate materials, and a simple and low-cost industrial application method for preparing the high tap density iron phosphate is lacking so far. Disclosure of Invention The application aims to provide a method for improving tap density of ferric phosphate. Further, the application discloses a preparation method of the high tap density ferric phosphate material. The inventor of the present application found that iron phosphate with irregular polyhedral morphology prepared by the method of the present application has higher tap density. A process for preparing iron phosphate dihydrate is disclosed, comprising adding an iron phosphate complex to a suspension containing iron phosphate dihydrate particles at a temperature of 50-130 ℃, the iron phosphate complex precipitating and forming an iron phosphate dihydrate product during decomplexing. The inventors of the present application have found that the iron phosphate dihydrate product obtained by the method of the present application has a higher tap density than the raw iron phosphate dihydrate particles in suspension. According to the invention, the temperature is, for example, 55 ℃, 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃, 85 ℃, 90 ℃, 95 ℃, 100 ℃, 105 ℃, 110 ℃, 115 ℃, 120 ℃, 125 ℃, 130 ℃, etc., preferably 70-110 ℃, more preferably 85-105 ℃. The iron phosphate dihydrate particles are nano-particles, micro-particles or particles of larger particle size of iron phosphate dihydrate (sometimes referred to simply as iron phosphate in the present invention, such as iron phosphate suspensions, iron phosphate particles, etc., depending on the context, iron phosphate dihydrate can be judged). The iron phosphate particles may be obtained by in situ synthesis, commercially available, or by grinding after commercial availability. Preferably, the iron phosphate nanoparticles are iron phosphate dihydrate particles having an average particle size of less than 950nm, more preferably an average particle size of less than 400nm. Preferably, the microparticles have an average particle size of 1 to 3000 microns. The suspension containing iron phosphate particles contains iron phosphate dihydrate particles, water, and may further contain phosphoric acid and/or an iron phosphate complex. If phosphoric acid and/or iron phosphate complexes are present, the weight ratio of phosphoric acid and iron phosphate complexes is 0.01-30% of the total weight of the suspension containing iron phosphate partic