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Method for preparing lithium iron pyrophosphate used as positive material for lithium ion battery

A technology for lithium iron pyrophosphate and lithium-ion batteries, which is applied in battery electrodes, chemical instruments and methods, circuits, etc. It can solve the problems of difficult to control the morphology of reaction products, difficult to increase discharge specific capacity, and uneven particle size distribution of materials. To achieve the effect of easy control of the operation process, excellent cycle life and good dispersion

Active Publication Date: 2014-05-28
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] At present, research on the synthesis of Li 2 FeP 2 o 7 The main method is to prepare the precursor by solid-phase ball milling, and then perform high-temperature calcination reaction, but this kind of preparation process has the disadvantages of complex and changeable process and high cost; it is easy to cause low purity of materials and large particles, so the synthesized The particle size distribution of the material is uneven, and the conductivity of the material itself is poor, resulting in a large demand for carbon sources
For example, the Chinese patent application with application number 201210255197 discloses a preparation method of lithium iron phosphate lithium ion battery cathode material, which adopts a two-step solid-state sintering method, which takes a long time and has a high sintering temperature, which is not easy to improve the discharge rate. Specific capacity, it is difficult to control the morphology of the reaction product

Method used

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  • Method for preparing lithium iron pyrophosphate used as positive material for lithium ion battery
  • Method for preparing lithium iron pyrophosphate used as positive material for lithium ion battery
  • Method for preparing lithium iron pyrophosphate used as positive material for lithium ion battery

Examples

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Embodiment 1

[0023] This embodiment includes the following steps:

[0024] Dissolve 0.025mol lithium carbonate, 0.025mol iron nitrate, 0.05mol ammonium dihydrogen phosphate and 0.1mol oxalic acid in 500mL water, control the pH to 5, stir at room temperature for 0.5h to obtain a sol, then raise the temperature to 80°C and keep this temperature for 2h , to form a gel, then dry the gel in a vacuum oven at 120°C, ball mill the obtained xerogel for 1 hour, grind it evenly, and then sinter it at 600°C under the protection of argon for 6 hours, Naturally cooled to room temperature, the finished product lithium iron pyrophosphate (Li 2 FeP 2 o 7 ).

[0025] X-ray powder diffraction analysis shows that the product obtained in this example is pure Li 2 FeP 2 o 7 , no other impurity phases were detected, and the crystallinity was high; from scanning electron microscope analysis, it was known that the particle dispersion of the obtained product was good, and the particle size was 400-600nm;

[...

Embodiment 2

[0028] This embodiment includes the following steps:

[0029] Dissolve 0.05mol lithium hydroxide, 0.025mol ferrous oxalate, 0.025mol pyrophosphoric acid and 0.05mol tartaric acid in 500mL water, control the pH to 4, stir at room temperature for 2h to obtain a sol, then raise the temperature to 60°C and keep it for 10h to make it Form a gel, then dry the gel in a vacuum drying oven at 120°C, ball mill the obtained xerogel for 2 hours, grind it evenly, and then sinter it at 600°C for 20 hours under the protection of nitrogen, and cool it down to room temperature naturally. The finished product lithium iron pyrophosphate (Li 2 FeP 2 o 7 ).

[0030] X-ray powder diffraction analysis shows that the product obtained in this example is pure Li 2 FeP 2 o 7 , no other impurity phases were detected, and the crystallinity was high; from scanning electron microscope analysis, it was known that the particle dispersion of the obtained product was good, and the particle size was 400-50...

Embodiment 3

[0033] This embodiment includes the following steps:

[0034](1) Dissolve 0.05mol lithium acetate, 0.025mol ferrous oxalate, 0.025mol pyrophosphoric acid and 0.05mol tartaric acid in 1000mL water, control the pH to 6, stir at room temperature for 1h to obtain a sol, then raise the temperature to 80°C and keep it for 8h, Make it form a gel, then dry the gel in a vacuum oven at 110°C, ball mill the obtained dry gel for 2 hours, grind it evenly, and then dry it at 500°C under the protection of a mixed gas of hydrogen and argon. Sintering for 10 hours, and naturally cooling to room temperature, the finished product lithium iron pyrophosphate (Li 2 FeP 2 o 7 ).

[0035] X-ray powder diffraction analysis shows that the product obtained in this example is pure Li 2 FeP 2 o 7 , no other impurity phases were detected, and the crystallinity was high; from scanning electron microscope analysis, it was known that the particle dispersion of the obtained product was good, and the part...

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Abstract

The invention relates to a method for preparing lithium iron pyrophosphate used as a positive material for a lithium ion battery. The method comprises the following steps: mixing a lithium source compound, an iron source compound, a phosphorus source compound and a chelating agent, used as raw materials, dissolving into water, and stirring at room temperature for 0.5-2h to obtain sol; heating to be at 50-100 DEG C and keeping the temperature for 2-10h to form gel; drying the gel in a vacuum drying oven at 100-120 DEG C to obtain dried gel; ball-milling the dried gel for 1-4h, grinding uniformly, sintering at 500-700 DEG C for 2-16h in protective atmosphere, and naturally cooling to be at room temperature to obtain the lithium iron pyrophosphate. The prepared lithium iron pyrophosphate particles are uniform, have high crystallinity degree and good dispersibility; the battery manufactured by the lithium iron pyrophosphate has high charging and discharging capacity and charging platform and good cycle life, and can meet various requirements of the lithium ion battery in practical application.

Description

technical field [0001] The invention relates to a method for preparing a cathode material of a lithium ion battery, in particular to a method for preparing lithium iron phosphate, an anode material of a lithium ion battery, by using a sol-gel technology. Background technique [0002] Lithium-ion batteries are widely used in electronic products, electric vehicles, and energy storage devices because of their advantages such as high working potential, high specific energy, high specific power, long cycle life, and environmental friendliness. Lithium-ion batteries are generally composed of positive electrode materials, negative electrode materials, electrolytes, diaphragms, etc. Among these components, active materials are the most important components of lithium-ion batteries and key active points for energy storage, especially positive electrode materials. , and its cost accounts for about half of the entire battery, so the cathode material largely determines the final perform...

Claims

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Application Information

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IPC IPC(8): H01M4/58
CPCC01B25/45H01M4/5825Y02E60/10
Inventor 郑俊超欧星张宝张佳峰
Owner CENT SOUTH UNIV
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