Method for preparing positive electrode material of LiFePO4 by phosphorous acid or salt thereof

A technology of lithium iron phosphate and phosphite, which is applied in chemical instruments and methods, phosphorus compounds, battery electrodes, etc., can solve problems such as uneven distribution, difficult to control the amount and structure, and achieve less time-consuming and low raw material costs , good cycle performance

Inactive Publication Date: 2008-12-31
FUJIAN NORMAL UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Fe 2 The distribution of P in lithium iron phosphate is not uniform, and it is difficult to control the concentration of Fe in the sample. 2 The amount and structure of P

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] According to Li + : Fe 2+ :PO 4 3-: The mol ratio of phosphorous acid is 1.10: 1.10: 0.999: 0.001 Take lithium hydroxide, ferrous carbonate, diammonium hydrogen phosphate and phosphorous acid, add the glucose of 1% of the lithium iron phosphate quality calculated according to reactant quality, Then add 95% ethanol aqueous solution, ball mill and mix with ordinary ball mill for 3 hours at the speed of 100 rpm, and dry in a vacuum desiccator at 100° C. under a pressure of 10 Pa. Placed in a high-purity nitrogen atmosphere, pre-calcined at 200°C for 3 hours, and cooled to room temperature to obtain a precursor pre-calcined material. Add 95% ethanol aqueous solution to the matrix calcined material again, ball mill and mix with ordinary ball mill for 12 hours at 300 r / min, and dry in a vacuum dryer at 100° C. under a pressure of 100 Pa. The dried powder was again placed in high-purity nitrogen and calcined at 550°C for 24 hours to obtain 2 P lithium iron phosphate.

Embodiment 2

[0031] According to Li + : Fe 2+ :PO 4 3- : the mol ratio of phosphorous acid is 0.95: 0.95: 0.70: 0.30 takes lithium carbonate, ferrous carbonate, diammonium hydrogen phosphate and phosphorous acid, adds the glucose of 20% of the lithium iron phosphate quality calculated according to reactant quality, then An aqueous solution of 60% acetone was added, ball milled with a common ball mill for 12 hours at a speed of 400 rpm, and dried in a vacuum desiccator at 50° C. and a pressure of 1000 Pa. The dried powder is placed in a high-purity argon atmosphere, heated from room temperature to 500 °C at a heating rate of 10 °C / min, pre-calcined with heat preservation for 10 hours, and cooled to room temperature to obtain a precursor pre-calcined material. Add 60% acetone aqueous solution to the matrix calcined material again, mill it with a high-energy ball mill for 12 hours at a speed of 600 rpm, and dry it in a vacuum dryer at 100° C. and a pressure of 1000 Pa. The dried powder wa...

Embodiment 3

[0033] According to Li + : Fe 2+ :PO 4 3- : NaH 2 PO 3 The mol ratio is 0.91: 0.95: 0.95: 0.05, lithium nitrate, ferrous chloride, ammonium dihydrogen phosphate and sodium hydrogen phosphite are weighed, and 10% starch of the lithium iron phosphate mass calculated according to the reactant mass is added, Then add deionized water, mill with a high-energy ball mill for 5 hours at a speed of 1000 rpm, and dry in a vacuum desiccator at 100° C. and a pressure of 2000 Pa. The prepared powder was placed in an atmosphere of a mixed gas of 90% by volume nitrogen and 10% by volume hydrogen, and the dried powder was heated from room temperature to 550° C. at a heating rate of 0.5 / min. Heat preservation and pre-calcination for 3 hours, and cool to room temperature to prepare the matrix pre-calcined material. Add deionized water to the matrix calcined material, mill it with a high-energy ball mill for 5 hours at a speed of 800 rpm, and dry it in a vacuum dryer at a pressure of 3000 P...

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Abstract

The invention relates to a method for preparing lithium iron phosphate by phosphorous acid or phosphite; the preparation method is as follows: lithium salt, ferrous salt, phosphate and phosphorous acid or phosphite are blended, added with carbon-containing compound, and further added with wet milling liquid, processed by ball milling and mixing, and dried at normal atmosphere or vacuum; the dried powder is sintered to prepare lithium iron phosphate cathode material. The lithium is one of or the mixture of lithium carbonate, lithium hydroxide, lithium oxalate, lithium acetate, lithium nitrate, lithium fluoride and lithium phosphate; the ferrous salt is one of or the mixture of iron oxalate, iron acetate, iron dichloride, ferrous sulfate or ferrous carbonate; the phosphate is one of or the mixture of ammonium phosphate, diammonium phosphate of monoammonium phosphate; the molecular formula of phosphite is AH2PO3, A2HPO3, EHPO3, E(H2PO3)2 or G(H2PO3)3; the carbon-containing compound is one of or the mixture of polypropylene, polyacrylamide, polyvinyl alcohol, glucose, cane sugar or starch. The method of the invention has simple preparing process and short time consumed, and the materials have good cycling performance under the heavy current discharging condition.

Description

technical field [0001] The invention relates to a method for preparing a lithium iron phosphate cathode material with large current discharge performance for lithium ion batteries, lithium batteries, lithium ion polymer batteries and supercapacitors by using phosphorous acid or phosphite. technical background [0002] With the promotion and use of new mobile electronic products, the quality requirements for lithium-ion batteries are getting higher and higher, and the quantity requirements are increasing. Lithium-ion batteries have the advantages of high voltage, large specific energy, long cycle life, good safety performance, small self-discharge, fast charge and discharge, and wide operating temperature range. It is a green chemical power source. At present, commercial lithium-ion batteries mostly use lithium cobalt oxide cathode materials. The disadvantage is that the price of lithium cobalt oxide is high and it is not friendly to the environment. Lithium cobalt oxide li...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B25/45H01M4/58
CPCY02E60/10
Inventor 童庆松卢阳施继成黄维静李变云
Owner FUJIAN NORMAL UNIV
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