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Method for preparing superfine iron phosphate through electrolytic method

A technology of fine phosphoric acid and electrolysis, applied in the direction of electrolysis components, electrolysis process, etc., can solve the problems of high production equipment requirements, large energy consumption, large consumption of raw materials, etc., achieve good social and economic benefits, low technical equipment requirements, and synthesis efficiency high effect

Active Publication Date: 2011-05-11
ZHEJIANG UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] There are many ways to synthesize iron phosphate, such as mixing ferrous sulfate with diammonium hydrogen phosphate solution, and ultrasonically irradiating the reaction solution to obtain iron phosphate products (Hirokazu Okawa*, Junpei Yabuki, Youhei Kawamura, Ichiro Arise, Mineo Sato.Synthesis of FePO 4 cathode material for lithium ion batteries by a sonochemical method.J.materials research bulletin.2008), the disadvantage of this method is that it requires high production equipment, large energy consumption, high cost, and is not suitable for large-scale production
[0005] Another example is to prepare ferric phosphate by reacting ferrous sulfide, dilute phosphoric acid, sodium chlorate and sodium hydroxide, the reaction equation: 6FeSO 4 +6H 3 PO 4 +NaClO 3 +12NaOH→6FePO 4 2H 2 O+6Na 2 SO 4 +NaCl+3H 2 O (Ma Guangcheng, Ding Shiwen, Li Weiping*. Synthesis and Performance Research of Iron Phosphate. J. Paint Industry. 1998.12), the disadvantage of this method is that the steps are complicated, the consumption of raw materials is large, and the cost is high
[0006] In addition, it is also possible to directly react sodium phosphate with iron sulfate to synthesize iron phosphate under the condition that the pH value is less than 2. This method is incomplete and has many impurities.

Method used

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  • Method for preparing superfine iron phosphate through electrolytic method
  • Method for preparing superfine iron phosphate through electrolytic method

Examples

Experimental program
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Effect test

Embodiment 1

[0034] In a 250mL plate and frame electrolytic cell, a pure iron electrode is used as the anode, a graphite rod is used as the cathode, the area is 5cm×5cm, 200mL of 0.1mol / L trisodium phosphate aqueous solution is used as the electrolyte, and 0.5mol / L dilute phosphoric acid is used The aqueous solution adjusts the pH of the reaction solution to 5, and the electrolytic cell is electrolyzed by direct current for 1 hour, and the current density is 200A / m 2 , the tank temperature is 10°C, after the reaction is over, use 1.05mL of 30% hydrogen peroxide to oxidize ferrous phosphate into a light yellow ferric phosphate precipitate, filter the electrolyte, wash the precipitate with deionized water, and place the precipitate in a vacuum drying oven at a temperature of 60 ℃ drying to a moisture content of 350ppm to obtain ultrafine iron phosphate (FePO 4 2H 2 (O) 0.98g, the scanning electron microscope (SEM) of gained superfine ferric phosphate after sintering at 650 ℃ sees figure 1 ...

Embodiment 2

[0036] In a 250mL plate-and-frame electrolytic cell, pure iron electrodes are used as the anode and cathode, with an area of ​​5cm×5cm, and a mixed solution of 150mL of 1mol / L potassium dihydrogen phosphate aqueous solution and 50mL of 0.3mol / L triammonium phosphate aqueous solution is the electrolyte , use 0.5mol / L dilute hydrochloric acid aqueous solution to adjust the pH of the reaction solution to 6, and conduct alternating current electrolysis to the electrolytic cell for 1h, and the current density is 5000A / m 2 , the tank temperature is 50°C, after the reaction is over, feed pure oxygen at a rate of 5mL / s for 1h to oxidize ferrous phosphate to ferric phosphate, filter the electrolyte, wash the precipitate with deionized water, and store the precipitate in a vacuum drying oven , dried at 80°C to a moisture content of 500ppm to obtain ultrafine iron phosphate (FePO 4 2H 2 O) 20.75g.

Embodiment 3

[0038]In a 250mL plate-and-frame electrolytic cell, steel electrodes are used as anodes, copper sheets are used as cathodes, and the area is 5cm×5cm. 200mL of 1.0mol / L disodium hydrogen phosphate solution is used as electrolyte, and 0.8mol / L dilute sulfuric acid is used. The aqueous solution adjusts the pH of the reaction solution to 1, conducts direct current electrolysis to the electrolytic cell for 2.5 hours, and the current density is 2200A / m 2 , the tank temperature is 25°C, after the reaction is over, use 29mL of 30% hydrogen peroxide to oxidize ferrous phosphate to ferric phosphate, filter the electrolyte, wash the precipitate with deionized water, dry the precipitate in a vacuum drying oven at 100°C until the moisture content is 350ppm, to obtain ultra-fine iron phosphate (FePO 4 2H 2 O) 26.3 g.

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Abstract

The invention discloses a method for preparing superfine iron phosphate through an electrolytic method. The method comprises the following steps of: regulating the pH of electrolyte to 1-10 by taking a phosphoric acid or an aqueous phosphate solution as the electrolyte, iron or an iron-containing alloy as an anode and a graphite rod, copper, iron or an iron alloy as a cathode and adopting the current density of 200-5000 A / m<2>; controlling electrolysis temperature between 10 DEG C and 90 DEG C; carrying out DC or AC electrolysis to synthesize ferrous phosphate; adding an oxidizer to oxidize into iron phosphate; and filtering, washing and drying sediments to prepare superfine iron phosphate powder. The invention sufficiently utilizes the low-cost iron or iron alloy as an iron source, creatively prepares the iron phosphate by adopting the electrolytic method and has the advantages of safe and simple synthesis method, low requirement for technical equipment, easy operation, low cost, higher synthesis efficiency, finer product granule, easy industrialization realization and better social and economic benefit.

Description

(1) Technical field [0001] The invention relates to a method for preparing superfine iron phosphate by electrolysis. (2) Background technology [0002] Iron phosphate is light yellow or light yellow white powder, tap density: 1.13~1.59g / cm 3 , bulk density 0.75~0.97g / cm 3 , Soluble in hydrochloric acid when heated, hardly soluble in other acids, almost insoluble in water, acetic acid, alcohol, exists in the form of blue iron in nature. [0003] At present, the lithium-ion battery market is developing rapidly, and iron phosphate is one of the raw materials for the preparation of lithium iron phosphate, the cathode material of lithium-ion batteries. The iron phosphate precursor with excellent performance plays a decisive role in the performance of lithium iron phosphate. [0004] There are many ways to synthesize iron phosphate, such as mixing ferrous sulfate with diammonium hydrogen phosphate solution, and ultrasonically irradiating the reaction solution to obtain iron phos...

Claims

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Application Information

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IPC IPC(8): C25B1/00
Inventor 张文魁钱灵超陶新永黄辉甘永平
Owner ZHEJIANG UNIV OF TECH