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CN-121974317-A - Method for preparing titanium-vanadium doped ferric phosphate

CN121974317ACN 121974317 ACN121974317 ACN 121974317ACN-121974317-A

Abstract

The invention belongs to the field of phosphate inorganic material preparation, and relates to a method for preparing titanium-vanadium doped ferric phosphate, which comprises the following steps of adding titanium and/or vanadium compounds into ferric phosphate complex solution to prepare ferric phosphate complex solution containing titanium and/or vanadium doped metal compounds, adding water into the mixed solution, and heating to obtain titanium and/or vanadium ion doped ferric phosphate, wherein the titanium compounds are selected from meta-titanic acid, nano titanium dioxide, titanyl sulfate, titanyl oxalate, titanium citrate, titanium lactate or titanium tartrate; the vanadium compound is vanadium trioxide, vanadium (IV) dioxide, vanadium pentoxide, vanadium monoxide, vanadyl sulfate or vanadium trichloride. In addition, alternatives to the change of the order of addition and the timing of addition are also provided. The method is simple in process, suitable for large-scale industrial production, and capable of improving the electrochemical performance of the power battery of the lithium iron phosphate material.

Inventors

  • MA XIAOLING
  • ZHANG RUI

Assignees

  • 林立新能源科技有限公司

Dates

Publication Date
20260505
Application Date
20260407

Claims (10)

  1. 1. A method for preparing titanium and/or vanadium doped ferric phosphate, comprising the steps of: s1, preparing a titanium and/or vanadium-containing ferric phosphate complex solution, namely adding a titanium and/or vanadium compound into the ferric phosphate complex solution, heating and stirring at a temperature of between 50 and 160 ℃ to obtain the titanium and/or vanadium-containing ferric phosphate complex solution; S2, preparing titanium and/or vanadium doped ferric phosphate dihydrate, namely adding water into the titanium and/or vanadium doped ferric phosphate complex solution obtained in the step S1, wherein the water adding amount is 0.3-10 times of the volume of the complex solution, heating and controlling the temperature between 60 ℃ and 150 ℃, preserving the temperature for 10min to 24h, and carrying out solid-liquid separation to obtain the titanium doped ferric phosphate dihydrate; Wherein the ratio of phosphorus to iron in the ferric phosphate complex solution is (2.5-8) 1, the mol ratio of doping element to iron element is (0.01-0.2) 1, and the doping element is titanium and/or vanadium; The titanium compound is metatitanic acid, nano titanium dioxide, titanyl sulfate, titanyl oxalate, titanium citrate, titanium lactate or titanium tartrate; the vanadium compound is vanadium trioxide, vanadium (IV) dioxide, vanadium pentoxide, vanadium monoxide, vanadyl sulfate or vanadium trichloride.
  2. 2. The method according to claim 1, wherein in the step S1, the ratio of phosphorus to iron in the iron phosphate complex solution is (3-6): 1, the molar ratio of the doping element to the iron element is (0.05-0.2): 1, and the doping element is titanium and/or vanadium.
  3. 3. The method of claim 1, wherein the titanium compound is meta-titanic acid, nano-titania, titanyl sulfate, and the vanadium compound is vanadium trioxide, vanadium (IV) dioxide, vanadium pentoxide, or vanadyl sulfate.
  4. 4. The method according to claim 1, wherein in the step S2, the water addition amount is 0.5-4 times of the volume of the complex solution, the heating control temperature is 80-120 ℃, and the temperature is kept for 10min-8 h.
  5. 5. The method of claim 1, wherein the iron phosphate complex solution is prepared by any one of the following methods: Mixing ferric oxide with 35-85wt% phosphoric acid solution, and preparing ferric phosphate complex solution at 60-160 ℃ or removing insoluble matters by solid-liquid separation to obtain ferric phosphate complex solution; reacting ferric phosphate with 35-85wt% phosphoric acid solution at 60-160 deg.c to obtain ferric phosphate complex solution or solid-liquid separating to eliminate insoluble matter to obtain ferric phosphate complex solution; Wherein the ratio of phosphorus to iron in the iron phosphate complex solution is (2.5-8): 1, and the feeding mole ratio of phosphoric acid and ferric oxide or ferric phosphate in the raw materials is referred to the feeding of the ratio of phosphorus to iron.
  6. 6. A method for preparing titanium and/or vanadium doped ferric phosphate, comprising the steps of: S11, preparing an iron phosphate complex solution containing doped elements, namely mixing ferric oxide, a phosphoric acid solution with the concentration of 35-85wt%, a titanium compound and/or a vanadium compound for reaction, wherein the reaction temperature is 60-160 ℃, and carrying out solid-liquid separation to obtain the iron phosphate complex solution containing titanium and/or vanadium; s2, preparing titanium and/or vanadium doped ferric phosphate dihydrate, namely adding water into the titanium and/or vanadium doped ferric phosphate complex solution obtained in the step S11, wherein the water addition amount is 0.3-10 times of the volume of the complex solution, heating and controlling the temperature between 60 ℃ and 150 ℃, preserving the temperature for 10min to 24h, and carrying out solid-liquid separation to obtain the titanium and/or vanadium doped ferric phosphate dihydrate; Wherein, the mixing reaction in the step S11 is operated by any one of the following methods, (a) ferric oxide, 35-85wt% of phosphoric acid solution and titanium compound and/or vanadium compound are directly mixed for reaction, (b) ferric oxide is firstly mixed with 35-85wt% of phosphoric acid solution and then titanium compound and/or vanadium compound are added for mixing reaction, or (c) titanium compound and/or vanadium compound are firstly mixed with 35-85wt% of phosphoric acid solution and then ferric oxide is added for mixing reaction; the ratio of phosphorus to iron in the ferric phosphate complex solution is (2.5-8) 1, the mol ratio of doping element to iron element is (0.01-0.2) 1, and the doping element is titanium and/or vanadium; The titanium compound is metatitanic acid, nano titanium dioxide, titanyl sulfate, titanyl oxalate, titanium citrate, titanium lactate or titanium tartrate, and the vanadium compound is vanadium trioxide, vanadium (IV) dioxide, vanadium pentoxide, vanadium monoxide, vanadyl sulfate or vanadium trichloride; When the ratio of phosphorus to iron in the iron phosphate complex solution is (2.5-8): 1, the feeding mole ratio of phosphoric acid to ferric oxide in the step S11 refers to the feeding of the ratio of phosphorus to iron.
  7. 7. The method according to claim 6, wherein in the step S11, the ratio of phosphorus to iron in the iron phosphate complex solution is (3-6) 1, the molar ratio of doping element to iron element is (0.05-0.2) 1, the doping element is titanium and/or vanadium, the titanium compound is metatitanic acid, nano titanium dioxide, titanyl sulfate, and the vanadium compound is vanadium trioxide, vanadium (IV) dioxide, vanadium pentoxide or vanadyl sulfate.
  8. 8. The method according to claim 6 or 7, wherein in step S2, the water addition amount is 0.5-4 times the volume of the complex solution, the heating control temperature is 80-120 ℃, and the temperature is kept for 10min-8 h.
  9. 9. A method of preparing titanium and vanadium doped ferric phosphate, the method comprising: S11, preparing an iron phosphate complex solution containing titanium and/or vanadium by one-time doping, namely mixing ferric oxide, a phosphoric acid solution with the concentration of 35-85wt% and a titanium compound and/or vanadium compound for reaction, wherein the reaction temperature is 60-160 ℃, and preparing the iron phosphate complex solution containing titanium or vanadium through solid-liquid separation; S12, preparing a secondary titanium and/or vanadium doped ferric phosphate complex solution, namely adding a titanium compound and/or a vanadium compound into the ferric phosphate complex solution containing titanium or vanadium obtained in the step S11, heating and stirring the mixture at the temperature of 50-160 ℃, and carrying out solid-liquid separation or not to obtain the secondary titanium and/or vanadium doped ferric phosphate complex solution; s2, preparing titanium and/or vanadium doped ferric phosphate dihydrate, namely adding water into the secondary titanium and/or vanadium doped ferric phosphate complex solution obtained in the step S12, wherein the water addition amount is 0.3-10 times of the volume of the complex solution, heating and controlling the temperature between 60 ℃ and 150 ℃, preserving the temperature for 10min to 24h, and carrying out solid-liquid separation to obtain the titanium and/or vanadium doped ferric phosphate dihydrate; wherein, the mixing reaction in the step S11 is carried out by any one of the following methods, (a) ferric oxide, 35-85wt% phosphoric acid solution and titanium compound and/or vanadium compound are directly mixed for reaction, (b) ferric oxide is firstly mixed with 35-85wt% phosphoric acid solution and then titanium compound and/or vanadium compound are added for mixing reaction, or (c) titanium compound and/or vanadium compound are firstly mixed with 35-85wt% phosphoric acid solution and then mixed for reaction with ferric oxide; the ratio of phosphorus to iron in the ferric phosphate complex solution is (2.5-8) 1, the mol ratio of doping element to iron element is (0.01-0.2) 1, and the doping element is titanium and/or vanadium; The titanium compound is metatitanic acid, nano titanium dioxide, titanyl sulfate, titanyl oxalate, titanium citrate, titanium lactate or titanium tartrate, and the vanadium compound is vanadium trioxide, vanadium (IV) dioxide, vanadium pentoxide, vanadium monoxide, vanadyl sulfate or vanadium trichloride; When the ratio of phosphorus to iron in the iron phosphate complex solution is (2.5-8): 1, the feeding mole ratio of phosphoric acid to ferric oxide in the step S11 refers to the feeding of the ratio of phosphorus to iron.
  10. 10. The method of claim 9, wherein a less soluble titanium or vanadium compound starting material is used in step S11 and a more soluble titanium or vanadium compound starting material is used in step S12.

Description

Method for preparing titanium-vanadium 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-vanadium doped ferric phosphate. Background Lithium iron phosphate (LiFePO 4) batteries have the advantages of lower raw material cost, higher working voltage platform, thermal stability, excellent electrochemical cycle performance and the like, and the demand of the batteries 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. CN118125410a discloses a preparation method of vanadium-doped ferric phosphate and lithium iron phosphate, wherein an iron source, a phosphorus source and a vanadium source are mixed and ground, and then dried and added with hydrogen peroxide to be stirred to obtain a mixed solution. CN118851127a discloses a titanium and vanadium doped ferric phosphate, which is prepared by forming a solution of titanium and ferrous salt, oxidizing to obtain titanium doped ferric phosphate dihydrate (substance M), and mixing with a solution of vanadium compound to obtain a vanadium and titanium containing ferric phosphate product. According to the method, ferrous sulfate is used as a raw material, vanadium is mixed with ferric phosphate solid, so that the doping of the vanadium is uneven, and the vanadium is doped in surface layer substances only. The realization of the uniform distribution of titanium/vanadium ions in the iron phosphate material is an important way for improving the electrochemical performance of the lithium iron phosphate material, and a preparation process of the iron phosphate for realizing the uniform doping of titanium/vanadium, which is simple in process and low in cost, is lacking so far. Disclosure of Invention The invention provides a preparation method of titanium and/or vanadium doped ferric phosphate, which is simple and convenient, and the titanium/vanadium in the prepared doped ferric phosphate is uniformly distributed. The application provides a method for preparing titanium and/or vanadium doped ferric phosphate, which comprises the following steps: s1, preparing a titanium and/or vanadium-containing ferric phosphate complex solution, namely adding a titanium and/or vanadium compound into the ferric phosphate complex solution, heating and stirring at a temperature of between 50 and 160 ℃ to obtain a titanium and/or vanadium-containing ferric phosphate complex solution doped with a metal compound; s2, preparing titanium and/or vanadium doped ferric phosphate dihydrate, namely adding water into the titanium or vanadium-containing ferric phosphate complex solution obtained in the step S1, wherein the water addition amount is 0.3-10 times of the volume of the complex solution, heating and controlling the temperature between 60 ℃ and 150 ℃, preserving the temperature for 10min to 24h, and carrying out solid-liquid separation to obtain the titanium doped ferric phosphate dihydrate; Wherein the ratio of phosphorus to iron in the ferric phosphate complex solution is (2.5-8) 1, the mol ratio of doping element to iron element is (0.01-0.2) 1, and the doping element is titanium and/or vanadium. The term "titanium-and/or vanadium-doped iron phosphate" in the present invention includes three cases of titanium-doped iron phosphate, vanadium-doped iron phosphate, titanium and vanadium-doped iron phosphate. The "molar ratio of the do