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Method for preparing nanometer lithium iron phosphate in liquid phase

A lithium iron phosphate, nano-scale technology is applied in the field of directly preparing nano-scale lithium iron phosphate, which can solve the problems of difficult application and high equipment requirements, and achieve the effect of controllable size and uniform particle size.

Inactive Publication Date: 2012-07-18
HENAN NORMAL UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

It can be seen that although the hydrothermal synthesis method is carried out in the liquid phase, submicron lithium iron phosphate particles with uniform particle size can be synthesized, but it needs to be carried out under high temperature and high pressure conditions, which requires high equipment and is not easy to apply in industry

Method used

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  • Method for preparing nanometer lithium iron phosphate in liquid phase
  • Method for preparing nanometer lithium iron phosphate in liquid phase
  • Method for preparing nanometer lithium iron phosphate in liquid phase

Examples

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example 1

[0016] Prepare 1mol.L according to Fe:P molar ratio of 1:1 -1 100ml of mixed aqueous solution of ferrous sulfate and phosphoric acid, put the mixed solution in a 500ml reaction vessel with a reflux condenser device, add 100ml of dimethyl sulfoxide and 15ml of 0.6% polyacrylamide solution successively, slowly add 3mol .L -1 Lithium hydroxide solution until the pH of the reaction solution is 7, then heated to the boiling point of the solution (108°C) and reacted for 2 hours, the product was filtered, washed with deionized water and absolute ethanol respectively, and vacuum-dried at 100°C for 10 hours to obtain this product Invent products. The product is detected by XRD powder diffraction as olivine structure pure phase LiFePO 4 ( figure 1 ), the particle size is 40-400nm ( figure 2 ).

example 2

[0018] Prepare 1mol.L according to Fe:P molar ratio of 1:1 -1 100ml of mixed aqueous solution of ferrous sulfate and phosphoric acid, put the mixed solution in a 500ml reaction vessel with a reflux condenser device, add 200ml of dimethyl sulfoxide and 1g of sodium dodecylbenzenesulfonate successively, and slowly add 2mol.L -1 Lithium hydroxide solution until the pH of the reaction solution is 7, then heated to the boiling point of the solution (115°C) and reacted for 1 hour, the product was filtered, washed with deionized water and absolute ethanol respectively, and dried in vacuum at 100°C for 10 hours to obtain this product Invent products. The obtained sample was detected by XRD powder diffraction as olivine structure pure phase LiFePO 4 , the particle size is 40-350nm.

example 3

[0020] Prepare 1mol.L according to Fe:P molar ratio of 1:1 -1 100ml of mixed aqueous solution of ferrous chloride and phosphoric acid, put the mixed solution in a 500ml reaction vessel with a reflux condenser device, add 100ml of ethylene glycol and 0.5g of cetyltrimethylammonium bromide successively, stir slowly Slowly add 1mol.L -1 Lithium hydroxide solution until the pH of the reaction solution is 6.5, then heated to the boiling point of the solution (106°C) and reacted for 2 hours, the product was filtered, washed with deionized water and absolute ethanol, and dried in vacuum at 120°C for 8 hours to obtain this product Invent products. The obtained sample was detected by XRD powder diffraction as olivine structure pure phase LiFePO 4 , the particle size is 40-350nm.

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Abstract

The invention discloses a method for preparing nanometer lithium iron phosphate in liquid phase, which is characterized in that: reaction can be quickly completed in normal-pressure liquid phase, the synthesized lithium iron phosphate powder has small and homogenous particle size, and the particle size is 50nm to 400nm. The invention adopts a technical scheme that: ferrite and phosphoric acid mixed aqueous solution with a given concentration is prepared according to an equivalent mol ratio, the mixed aqueous solution is placed into a reactor, polarity organic solvent with a high boiling point such as dimethylsulfoxide with a volume ratio to the aqueous solution of 0.5 to 2:1 and 0.5 to 3 percent of crystal growth inhibitors such as polyacrylamide are added, lithium hydroxide solution is slowly added during the blending until the pH value of the reaction solution is 6 to 7, then the mixed solution is heated to the boiling point to have refluxing reaction for 0.5 to 3 hours, and products are conventionally filtered, washed and vacuum dried to obtain the nanometer lithium iron phosphate. The product is used as an anode material of a lithium-ion battery.

Description

technical field [0001] The invention belongs to a preparation method of a positive electrode material of a lithium ion battery, in particular to a method for directly preparing nanoscale lithium iron phosphate under normal pressure liquid phase conditions. Background technique [0002] The theoretical capacity of lithium iron phosphate is 170mAh / g, and the discharge voltage is 3.4V. It has excellent safety performance and cycle performance, and the material has a wide range of raw materials, low price, and no pollution to the environment. It is considered to be a power lithium-ion battery with great potential. Materials have become a hot spot in research and development in recent years. However, lithium iron phosphate itself also has some defects. The first is that its special structure hinders the deintercalation rate of lithium ions; the second is that the electronic conductivity is poor, resulting in poor high-rate discharge performance. According to the above defects, p...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B25/45B82Y40/00
Inventor 常照荣刘瑶汤宏伟李苞赵海丽黄静
Owner HENAN NORMAL UNIV
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