Search

CN-121990543-A - Method for preparing titanium-doped ferric phosphate

CN121990543ACN 121990543 ACN121990543 ACN 121990543ACN-121990543-A

Abstract

The invention belongs to the technical field of phosphate inorganic materials, and relates to a method for preparing titanium-doped ferric phosphate. The method comprises the following steps of S1, preparing a titanium-containing ferric phosphate complex solution, S2, mixing a part of the titanium-containing ferric phosphate complex solution obtained in S1 with water, heating and controlling the temperature to be 60-150 ℃, preserving heat for 10min-2h to form a titanium-doped ferric phosphate suspension, S3, adding the rest titanium-containing ferric phosphate complex solution into the suspension obtained in S2, heating and controlling the temperature to be 60-150 ℃, preserving heat for 10min-24h, and carrying out solid-liquid separation to obtain the titanium-doped ferric phosphate hydrate. The method can improve the yield of the titanium doped ferric phosphate, simultaneously improve the titanium doping amount, and overcome the problem that the yield of the ferric phosphate is drastically reduced due to the improvement of the titanium compound input amount.

Inventors

  • MA XIAOLING
  • ZHANG RUI

Assignees

  • 林立新能源科技有限公司

Dates

Publication Date
20260508
Application Date
20260410

Claims (8)

  1. 1. A method for preparing titanium doped ferric phosphate, comprising the steps of: s1, preparing a titanium-containing ferric phosphate complex solution, wherein the titanium-containing ferric phosphate complex solution is prepared by any one of the following methods 1-4: adding a titanium compound into an iron phosphate complex solution, heating and stirring, and mixing at a temperature of between 60 and 160 ℃; The method 2 comprises the steps of directly mixing ferric oxide, 35-85wt% of phosphoric acid solution and titanium compound for reaction, wherein the reaction temperature is controlled between 60 ℃ and 160 ℃; The method 3 comprises the steps of firstly mixing ferric oxide with 35-85wt% of phosphoric acid solution, then adding titanium compound for mixing reaction, and controlling the reaction temperature between 60 ℃ and 160 ℃; The method 4 comprises the steps of firstly mixing titanium compound with 35-85wt% of phosphoric acid solution, then adding the mixture to be mixed with ferric oxide, and controlling the temperature to react at 60-160 ℃; S2, preparing a titanium-doped ferric phosphate hydrate suspension, namely taking a part of the titanium-containing ferric phosphate complex solution obtained in the step S1, mixing the solution with water, heating and controlling the temperature to be 60-150 ℃, and preserving the temperature for 10min-2h to form the titanium-doped ferric phosphate hydrate suspension, wherein the volume of the titanium-containing ferric phosphate complex solution obtained in the step S1 is 3-20% of the total volume of the titanium-containing ferric phosphate complex solution obtained in the step S1; S3, preparing titanium-doped ferric phosphate, namely adding the rest titanium-containing ferric phosphate complex solution obtained in the step S1 into the suspension obtained in the step S2, heating and controlling the temperature to be 60-150 ℃, preserving the heat for 10min-24h, and carrying out solid-liquid separation to obtain titanium-doped ferric phosphate hydrate; Wherein, the In the step S1, the ratio of phosphorus to iron in the ferric phosphate complex solution is (2.5-8) 1, and the mol ratio of doped titanium element to iron element is (0.01-0.2) 1, wherein the titanium compound is metatitanic acid, nano titanium dioxide, titanyl sulfate, titanyl oxalate, titanium citrate, titanium lactate or titanium tartrate; The volume of water used in the step S2 is 0.5-10 times of the volume of the solution of the titanium-containing ferric phosphate complex.
  2. 2. The method according to claim 1, wherein in the step S1, the reaction temperature is controlled between 70 ℃ and 110 ℃, the titanium compound is metatitanic acid, nano titanium dioxide or titanyl sulfate, and the molar ratio of the doped titanium element to the iron element is (0.05-0.2): 1.
  3. 3. The method according to claim 1, wherein in the step S2, the volume of water is 0.5-4 times of the volume of the solution of the titanium-containing ferric phosphate complex, the temperature is controlled to be 70-110 ℃, the heat preservation time is 0.5-1.5h, and in the step S3, the residual complex solution is added in a way of one-time addition or continuous batch addition, the temperature is controlled to be 70-110 ℃, and the heat preservation time is 1h-10h.
  4. 4. A method according to any one of claims 1-3, wherein the method further comprises the steps of: S4, recycling the mother liquor obtained by filtering the S3 to replace part of 35-85wt% of phosphoric acid, and preparing the titanium-containing ferric phosphate complex solution in the step S1.
  5. 5. The method of claim 1, wherein step S2 is replaced by step S22 and step S3 is replaced by step S33, said steps S22 and S33 being: S22, mixing the titanium-doped ferric phosphate hydrate seed crystal with water to form a suspension containing titanium-doped ferric phosphate hydrate; s33, adding the titanium-containing ferric phosphate complex solution obtained in the step S1 into the suspension of the step S22, heating and controlling the temperature to be 60-150 ℃, reacting for 10min-24h, and carrying out solid-liquid separation to obtain titanium-doped ferric phosphate hydrate; Wherein the volume ratio of water in S22 to the volume ratio of the titanium-containing iron phosphate complex solution in S33 is between 1:2 and 4:1.
  6. 6. The method of claim 5, wherein the titanium doped ferric phosphate hydrate seed is a nanoparticle or microparticle, and is prepared by grinding or directly.
  7. 7. The method according to claim 5 or 6, wherein the titanium-doped ferric phosphate hydrate seed crystal is obtained by mixing a titanium-containing ferric phosphate complex solution with 5-40 times of water, heating to 60-150 ℃, reacting for 10min-1h to obtain a titanium-doped ferric phosphate crystal suspension, and separating solid from liquid to obtain titanium-doped ferric phosphate hydrate particles serving as seed crystals.
  8. 8. The method according to claim 5, wherein the suspension obtained in step S3 of claim 1 or the suspension obtained in step S33 of claim 5 before solid-liquid separation is mixed with water in place of the suspension obtained in step S22 of the subsequent batch for the preparation of the titanium-doped ferric phosphate hydrate of the subsequent batch, the volume ratio of water to the added titanium-doped ferric phosphate complex solution of the subsequent batch being between 1:2 and 4:1.

Description

Method for preparing titanium-doped ferric phosphate Technical Field The invention belongs to the field of phosphate inorganic material preparation, and particularly relates to a method for preparing titanium-doped ferric phosphate. Background The lithium iron phosphate (LiFePO 4) battery has the advantages of lower raw material cost, higher working voltage platform, higher thermal stability, excellent electrochemical cycle performance and the like, and the demand of the lithium iron phosphate (LiFePO 4) battery in the fields of power batteries and energy storage is in explosive growth trend. In the LiFePO 4 crystal structure, lithium ions have one-dimensional diffusion channels, while FeO 6 octahedra are separated by PO 43- tetrahedra, failing to form a continuous FeO 6 octahedral network, resulting in lower electron conductivity and ion mobility. The surface carbon coating can effectively improve the electronic conductivity of the material, and then the higher carbon coating amount is easy to reduce the compaction density of the material, so that the energy density of the power battery is reduced. To solve the above problems, liFePO 4 materials can be modified by ion doping. Ion doping means doping certain metal ions (Ti, V, ni and the like) with good conductivity in LiFePO 4 crystal lattice so as to reduce the resistance of Li + in diffusing along a one-dimensional path, promote the migration and diffusion of lithium ions and electrons and improve the multiplying power performance and electrochemical performance of LiFePO 4 material. CN 117842954A is prepared by mixing a soluble titanium salt, ferric phosphate dihydrate and a solvent with each other, and sintering at high temperature. The process may have the problem of uneven dispersion of titanium ions in the industrial process. CN 119018867A prepares the titanium doped ferric phosphate precursor by uniformly mixing a phosphorus source, an iron source and a titanium source and combining a hydrothermal reaction. The hydrothermal reaction requires high temperature and high pressure conditions, and is difficult to industrialize on a large scale. Disclosure of Invention The applicant has studied a method for doping with elements of titanium and vanadium during the preparation of iron phosphate using decomplexing of iron phosphate complexes, which is described in a further patent application. However, in the process of preparing the titanium-doped ferric phosphate material, the applicant found that when the high titanium element doping amount is obtained by increasing the input amount of the titanium compound, a reverse relationship between the increase of the titanium content and the yield of the titanium-doped ferric phosphate occurs, that is, the increase of the input amount of the titanium compound may lead to a sharp decrease in the yield of ferric phosphate or require an excessively long decomplexing crystallization reaction time, but the increase of the titanium doping amount is not obvious. This is very disadvantageous for the commercial production of titanium doped iron phosphate products, especially for the preparation of high titanium doped iron phosphate products. The invention provides a preparation method of titanium-doped ferric phosphate, which has the advantages of simple process, low cost, high titanium doping content, uniform doping and high yield. The application provides a method for preparing titanium doped ferric phosphate, which comprises the following steps: s1, preparing a titanium-containing ferric phosphate complex solution, wherein the titanium-containing ferric phosphate complex solution is prepared by any one of the following methods 1-4: adding a titanium compound into an iron phosphate complex solution, heating and stirring, and mixing at a temperature of between 60 and 160 ℃; The method 2 comprises the steps of directly mixing ferric oxide, 35-85wt% of phosphoric acid solution and titanium compound for reaction, wherein the reaction temperature is controlled between 60 ℃ and 160 ℃; The method 3 comprises the steps of firstly mixing ferric oxide with 35-85wt% of phosphoric acid solution, then adding titanium compound for mixing reaction, and controlling the reaction temperature between 60 ℃ and 160 ℃; The method 4 comprises the steps of firstly mixing titanium compound with 35-85wt% of phosphoric acid solution, then adding the mixture to be mixed with ferric oxide, and controlling the temperature to react at 60-160 ℃; S2, preparing a titanium-doped ferric phosphate hydrate suspension, namely taking a part of the titanium-containing ferric phosphate complex solution obtained in the step S1, mixing the solution with water, heating and controlling the temperature to be 60-150 ℃, and preserving the temperature for 10min-2h to form the titanium-doped ferric phosphate hydrate suspension, wherein the volume of the titanium-containing ferric phosphate complex solution obtained in the step S1 is 3-20% of the total volume of the titan