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Method for preparing battery-grade iron phosphate by using ferrophosphorus

An iron phosphate, battery-grade technology, applied in the field of phosphate, can solve the problems of increasing the production cost of lithium iron phosphate, high cost of iron phosphate, and high cost of iron salt, and achieve the effects of stable product quality, less impurity content, and uniform particle size distribution.

Active Publication Date: 2013-05-08
WENGFU (GRP) CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, in the process of industrial production, on the one hand, it is difficult to effectively control all reaction areas to achieve a uniform pH value through lye, which will cause the hydrolysis of ferric iron, resulting in impurities; on the other hand, the use of ammonia or other lye increases The production cost of lithium iron phosphate may introduce impurities at the same time. At the same time, due to the high cost of iron salt in the raw material, the cost of iron phosphate is relatively high

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0016] Example 1: Step 1: Weigh 20 grams of ferrophosphorus ground to 200 mesh, and add the concentration to be 6 mol L -1 Phosphoric acid solution 250 ml, the concentration is 6 mol L -1 250 ml of nitric acid solution, stirred evenly, heated to 90°C, kept warm for 2 hours, heated to dissolve, and filtered.

[0017] Step 2: Heat the above-mentioned filtrate to concentrate 50% by volume ratio, recrystallize impurity elements, and separate impurities by membrane filtration with a filter membrane with a pore size of 0.5 microns.

[0018] Step 3: Add 100ml of ferric phosphate sol prepared by ethanol solvent to the filtrate after membrane filtration, wherein the concentration of ferric phosphate is 0.006 mol L -1 , stirred at a constant temperature at 65°C for 2 hours, the ferric phosphate sol causes the precipitation of ferric phosphate in the solution, and then the precipitate is filtered, washed and dried to prepare battery-grade ferric phosphate.

Embodiment 2

[0019] Example 2: Step 1: Weigh 20 grams of ferrophosphorus ground to 300 mesh, and add the concentration to be 6 mol L -1 Phosphoric acid solution 250 ml, the concentration is 6 mol L -1 250 ml of hydrochloric acid solution, stirred evenly, heated to 90°C, kept warm for 2 hours, heated to dissolve, and filtered.

[0020] Step 2: Heat the above filtrate to concentrate 50% by volume ratio, recrystallize impurity elements, and separate impurities by membrane filtration with a filter membrane with a pore size of 0.1 micron.

[0021] Step 3: Add 100ml of ferric phosphate sol prepared by ethanol solvent to the filtrate after membrane filtration, wherein the concentration of ferric phosphate is 0.004 mol L -1 , stirred at a constant temperature at 85°C for 2 hours, the ferric phosphate sol causes the precipitation of ferric phosphate in the solution, and then the precipitate is filtered, washed and dried to prepare battery-grade ferric phosphate.

Embodiment 3

[0022] Example 3: Step 1: Weigh 20 grams of ferrophosphorus ground to 300 mesh, and add the concentration to be 6 mol L -1 Phosphoric acid solution 250 ml, the concentration is 6 mol L -1 250 ml of sulfuric acid solution, stirred evenly, heated to 90°C, kept warm for 2 hours, heated to dissolve, and filtered.

[0023] Step 2: Heat the above-mentioned filtrate to concentrate 50% by volume ratio, recrystallize impurity elements, and separate impurities by membrane filtration with a filter membrane with a pore size of 4 microns.

[0024] Step 3: Add 100ml of ferric phosphate sol prepared from deionized water to the filtrate after membrane filtration, wherein the concentration of ferric phosphate is 0.005 mol L -1 , stirred at a constant temperature at 95°C for 2 hours, the iron phosphate sol causes the precipitation of iron phosphate in the solution, and then the precipitate is filtered, washed, and dried to prepare battery-grade iron phosphate.

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Abstract

The invention discloses a method for preparing battery-grade iron phosphate by using ferrophosphorus. According to the method, ferrophosphorus is grinded into particles with a certain particle size, and is heated and dissolved in a mixed acid solution; the mixture is filtered, such that a filtrate is obtained; the filtrate is subjected to physicochemical methods such as re-crystallization, membrane filtration, carbon absorption, complex concealment, and the like, such that impurity elements are removed; the filtrate is concentrated, and is heated to a temperature of 60-95 DEG C; iron phosphate solution induction is carried out, such that iron phosphate is prepared. Therefore, high-purity spherical battery-grade iron phosphate with micro size is obtained. With the method, prepared iron phosphate has the advantages of low impurity content, and uniform particle size distribution. The iron phosphate is suitable to be used for further preparing battery-type lithium iron phosphate.

Description

technical field [0001] The present invention relates to phosphates, in particular to a method for preparing battery-grade iron phosphate from ferrophosphorus. Background technique [0002] Lithium iron phosphate has excellent properties such as high theoretical capacity (170mAh / g), high working voltage (voltage platform of about 3.5V), good cycle performance, no memory effect, etc., and has the advantages of low price and environmental friendliness, so it has the potential to replace Higher cost LiCoO 2 It will become a new generation of lithium-ion battery cathode material, and is expected to become an important material for large energy storage batteries required by electric vehicles. [0003] The solid-state reaction method is currently widely used in the production and research of lithium iron phosphate, and iron phosphate has gradually become an important precursor for the production of lithium iron phosphate in the carbothermal reduction method. In CN 101337666A,...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B25/37
Inventor 林倩杨三可肖仁贵刘飞曹建新解田李子燕
Owner WENGFU (GRP) CO LTD
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