CN-116750742-B - Preparation method of sodium iron phosphate material and sodium iron phosphate material

CN116750742BCN 116750742 BCN116750742 BCN 116750742BCN-116750742-B

Abstract

The invention relates to a preparation method of a sodium iron phosphate material and the sodium iron phosphate material, and the method comprises the steps of 1) dissolving a di/trivalent iron source in deionized water to prepare a solution A. 2) Dissolving alkaline substances in deionized water to prepare a solution B, dropwise adding the solution B into the solution A, stirring until the pH value of the solution is=4-8, centrifugally filtering to obtain slurry, 3) dissolving chloride, fluoride and phosphate in deionized water to prepare a solution C, dispersing the slurry obtained in the step 2) in the solution C, stirring for 0.5-24 h, filtering and drying to obtain the target product. The invention provides a novel method for efficiently preparing nano sodium iron phosphate by using a two-step granularity control method under a low-temperature condition. The invention realizes the room-temperature, rapid and efficient nano-preparation of the sodium iron phosphate product by utilizing the rapid nucleation of the precipitation reaction and the in-situ conversion of anion exchange.

Inventors

ZHANG DONGBIN
TENG AIJUN
YUAN XINRAN
LIU TIANHAO
DAI YU
YIN XIANGLU
PENG XIANZHU
ZENG ZEHUA

Assignees

鞍钢集团北京研究院有限公司

Dates

Publication Date: 20260505
Application Date: 20230625

Claims (7)

1. The preparation method of the sodium iron phosphate material is characterized in that the method adopts a two-step granularity control method to prepare the nano sodium iron phosphate material under the condition of room temperature, and specifically comprises the following steps: 1) Dissolving a di/trivalent iron source in deionized water to prepare a solution A; 2) Dissolving an alkaline substance in deionized water, preparing a solution B, dropwise adding the solution B into the solution A, continuously stirring until the pH value of the solution is=4-8, and centrifugally filtering to obtain slurry; 3) Dissolving chloride, fluoride and phosphate in deionized water to prepare a solution C, dispersing the slurry obtained in the step 2) in the solution C, continuously stirring for 0.5-24 h, filtering and drying to obtain a target product; the concentration ratio of chloride to fluoride to phosphate in the solution C is 0-1:10, and the molar concentration ratio of the di/ferric iron source to phosphate is 1:1-1:3; The chemical formula of the sodium iron phosphate material is Na x FeO y PO 4 F a Cl b , x is more than or equal to 0 and less than or equal to 3, y is more than or equal to 0 and less than or equal to 1, a+b is more than or equal to 0 and less than or equal to 1, the microcosmic appearance is nano-particle.
2. The method for preparing a sodium iron phosphate material according to claim 1, wherein the di/trivalent iron source is one or more of ferrous sulfate, ferric sulfate, ferrous chloride, ferric nitrate and ferrous oxalate.
3. The method for preparing the sodium iron phosphate material according to claim 1, wherein the concentration of the iron source in the solution A is 0.1-5.0 mol/L.
4. The method for preparing sodium iron phosphate material according to claim 1, wherein the alkaline substance is one or more of sodium hydroxide, potassium hydroxide, ammonia water, sodium carbonate and sodium bicarbonate.
5. The method for preparing the sodium iron phosphate material according to claim 1, wherein the concentration of the alkaline substance in the solution B is 0.1-5.0 mol/L.
6. The method for preparing the sodium iron phosphate material according to claim 1, wherein the chloride is one or more of sodium chloride, potassium chloride and ammonium chloride, the fluoride is one or more of sodium fluoride, potassium fluoride and ammonium fluoride, and the phosphate is one or more of sodium dihydrogen phosphate, disodium hydrogen phosphate and sodium phosphate.
7. The method for preparing the sodium iron phosphate material according to claim 1, wherein the average particle size of the sodium iron phosphate material is 50-200 nm.

Description

Preparation method of sodium iron phosphate material and sodium iron phosphate material Technical Field The invention relates to the field of electrode materials, in particular to a preparation method of a sodium iron phosphate material and the sodium iron phosphate material thereof, and the material can be used as an electrode material of lithium, sodium, potassium and other alkali metal secondary batteries. Background The polyanion compound is an alkali metal secondary battery electrode material with excellent performance due to excellent ion migration efficiency, good structure and thermal stability. Vanadium phosphate/sodium iron is a typical polyanion compound, and is widely paid attention to because of the advantages of stable structure, high safety and the like. Compared with the sodium vanadium phosphate, the sodium iron phosphate has wider raw material sources, lower cost and larger competitiveness in practical application. At present, the traditional preparation method of the sodium iron phosphate material is mainly concentrated in methods such as a high-temperature solid-phase synthesis method, a sol-gel method, an electrochemical synthesis method and the like, the preparation process of the sodium iron phosphate material often involves harsh conditions such as high vacuum, specific atmosphere, high temperature and the like, the operation is more complicated, the preparation cost is higher, and meanwhile, the prepared sodium iron phosphate material has larger microscopic granularity and generally reaches the mu m level. Because of poor electron conductivity of the sodium iron phosphate, the larger particle size can restrict the sodium storage performance of the prepared sodium iron phosphate material. Before the process, in order to solve the problems of poor conductivity and the like of polyanion compounds such as sodium vanadium phosphate and the like, the project group personnel put forward a nanocrystallization synthesis thought in Chinese invention patents (202210162593.6 and 202210249477.8), and researches prove that the polyanion compounds with smaller granularity are favorable for improving the electron/ion migration performance of the material. It is easy to deduce that the nano design and preparation of the sodium iron phosphate are beneficial to improving the electron/ion transport efficiency of the material, so that the sodium iron phosphate product with excellent performance is obtained. However, so far, researches on efficient preparation technology of sodium iron phosphate nanocrystallization have been freshly reported. Disclosure of Invention The invention aims to provide a preparation method of a sodium iron phosphate material and the sodium iron phosphate material thereof, and provides a novel method for efficiently preparing nano sodium iron phosphate by utilizing a two-step granularity control method under a low-temperature condition. According to the characteristic of small Ksp of the iron hydroxide and the characteristic of large reaction rate constant of the precipitation reaction, the iron ions are rapidly precipitated under the alkaline condition to form the iron hydroxide precursor with controllable granularity. Then, the ion exchange effect of anions such as PO 43-、F-、Cl- and OH - is utilized, so that the nano sodium iron phosphate material is obtained. The invention realizes the room-temperature, rapid and efficient nano-preparation of the sodium iron phosphate product by utilizing the rapid nucleation of the precipitation reaction and the in-situ conversion of anion exchange. In order to achieve the above purpose, the invention adopts the following technical scheme: The preparation method of the sodium iron phosphate material adopts a two-step granularity control method to prepare the nano sodium iron phosphate material under the condition of room temperature, and specifically comprises the following steps: 1) Dissolving a di/trivalent iron source into deionized water to prepare a solution A, wherein the di/trivalent iron source is one or more of ferrous sulfate, ferric sulfate, ferrous chloride, ferric nitrate, ferric oxalate and other di/trivalent inorganic/organic metal salts of iron. The concentration of the iron source in the solution A is 0.1 to 5.0mol/L. 2) And (3) dissolving an alkaline substance in deionized water to prepare a solution B, wherein the alkaline substance is one or more of sodium hydroxide, potassium hydroxide, ammonia water, sodium carbonate, sodium bicarbonate and other aqueous solutions which are alkaline. The concentration of the alkaline substance in the solution B is 0.1 to 5.0mol/L. Dropwise adding the solution B into the solution A at a certain dropwise speed, continuously stirring until the pH value of the solution is=4-8, and centrifugally filtering to obtain slurry; 3) Dissolving chloride and/or fluoride and phosphate in deionized water to prepare a solution C, wherein the chloride is one or more of sodium chloride, potassium chloride