Preparation method of metal-doped lithium iron phosphate

A lithium iron phosphate, metal technology, applied in the field of lithium ion battery cathode materials, can solve the problems of poor cycle performance and mechanical processing performance, and achieve the effects of good mechanical processing performance and rate performance, high volume energy density and cycle performance.

Pending Publication Date: 2020-05-22
KUNMING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] In order to improve the cycle performance and poor machinability of nano-lithium iron phosphate under high current density, the application provides a method for preparing lithium iron phosphate doped with metals and having good machinability. The specific steps are as follows :

Method used

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  • Preparation method of metal-doped lithium iron phosphate
  • Preparation method of metal-doped lithium iron phosphate
  • Preparation method of metal-doped lithium iron phosphate

Examples

Experimental program
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Effect test

Embodiment 1

[0024] A preparation method of doped metal lithium iron phosphate, the specific steps are as follows:

[0025] (1) Preparation of precursor: Add iron source (mixed with ferrous sulfate and ferrous nitrate at a mass ratio of 1:1) and phosphorus source (mixed with ammonium dihydrogen phosphate and diammonium hydrogen phosphate at a mass ratio of 1:1) into water to prepare Mixed solution, the concentration of iron in the mixed solution is 0.1mol / L, the molar ratio of iron and phosphorus is Fe:P=1:1, the mixed solution is stirred vigorously and then added hydrogen peroxide to obtain flocculent precipitation, hydrogen peroxide and Molar ratio H of iron element in iron source 2 o 2 : Fe=0.6:1, filter after stirring for 4 hours, wash the precipitate with deionized water repeatedly for residual impurities, and obtain the amorphous iron phosphate precursor after drying;

[0026] (2) Precursor intercalation of lithium source: disperse lithium source (lithium carbonate, lithium hydroxi...

Embodiment 2

[0033] A preparation method of doped metal lithium iron phosphate, the specific steps are as follows:

[0034] (1) Preparation of precursor: add iron source (ferrous chloride) and phosphorus source (diammonium hydrogen phosphate) into water to form a mixed solution. The concentration of iron in the mixed solution is 1mol / L, and the molar ratio of iron to phosphorus It is Fe:P=0.8:1.2, the mixed solution is stirred vigorously and then added hydrogen peroxide to obtain flocculent precipitation, the molar ratio H of hydrogen peroxide to iron element in the iron source 2 o 2 : Fe=0.8:1, after stirring for 8 hours, filter, rinse the precipitate with deionized water repeatedly for residual impurities, and obtain the amorphous iron phosphate precursor after drying;

[0035] (2) Precursor intercalation of lithium source: disperse lithium source (lithium acetate) and reducing agent tartaric acid into organic solvent ethanol to obtain an organic solution, the molar ratio of lithium sou...

Embodiment 3

[0038] A preparation method of doped metal lithium iron phosphate, the specific steps are as follows:

[0039] (1) Preparation of precursor: add iron source (ferrous oxalate) and phosphorus source (diammonium hydrogen phosphate) into water to form a mixed solution, the concentration of iron in the mixed solution is 2mol / L, and the molar ratio of iron and phosphorus is Fe :P=1.2:0.8, after the mixed solution is vigorously stirred, hydrogen peroxide is added to obtain a flocculent precipitate, and the molar ratio of hydrogen peroxide to iron in the iron source is H 2 o 2:Fe=1:1, after stirring for 12 hours, filter, wash the precipitate with deionized water repeatedly to remove residual impurities, and dry to obtain the amorphous iron phosphate precursor;

[0040] (2) Precursor intercalation of lithium source: disperse lithium source (lithium nitrate) and reducing agent ascorbic acid into the organic solvent propanol to obtain an organic solution, the molar ratio of lithium sour...

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Abstract

The invention discloses a preparation method of metal-doped lithium iron phosphate. The preparation method comprises the following steps: mixing an iron source, a phosphorus source and hydrogen peroxide to obtain a flocculent precipitate, and carrying out filtering, washing and drying successively to obtain a precursor; dispersing a lithium source and a reducing agent into an organic solvent, adding the precursor to prepare a suspension, stirring the suspension, and conducting centrifuging, washing and vacuum drying successively to obtain an off-white precipitate; uniformly mixing the off-white precipitate with a doping metal source, and carrying out annealing to obtain a spherical lithium iron phosphate positive electrode material. The crystallization degree of the material is controlledby controlling a molar ratio of raw materials, sintering temperature and heat preservation time, so a final product has good rate capability and cycle performance.

Description

technical field [0001] The invention relates to the field of positive electrode materials for lithium ion batteries, in particular to a method for preparing lithium iron phosphate doped with metal. Background technique [0002] With the consumption of fossil fuels, the problem of environmental pollution is becoming more and more serious. In clean energy storage equipment, lithium-ion batteries are getting more and more attention. The cathode material is the key material for lithium-ion batteries. Compared with many commercially used cathode materials, lithium iron phosphate has a high capacity (170mAh / g), It has the advantages of high discharge voltage and no obvious capacity attenuation after long cycle. As far as the current research status of lithium iron phosphate is concerned, there are still disadvantages such as poor electrical conductivity, low tap density, and serious capacity fading under low temperature use. These deficiencies hinder the application of lithium i...

Claims

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Application Information

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IPC IPC(8): C01B25/45H01M4/58H01M4/62H01M10/0525
CPCC01B25/45H01M4/5825H01M4/626H01M10/0525C01P2004/03C01P2006/40Y02E60/10
Inventor 张正富曹赫刘金坤
Owner KUNMING UNIV OF SCI & TECH
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