Preparation method of multicrystal LiFePO4 powder having olivine structure

A technology of olivine structure and H2PO4, which is applied in the direction of structural parts, chemical instruments and methods, rare earth metal compounds, etc., can solve the problems that are not conducive to the electrochemical performance of materials, the purity of synthetic materials is not high, and the particle size is large, so as to improve electronic performance. The effect of electrical conductivity, fine particles, and low firing temperature

Inactive Publication Date: 2003-04-16
TSINGHUA UNIV
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  • Claims
  • Application Information

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Problems solved by technology

The disadvantages of this method are that the purity of the synthetic material is not high, the temperature is high, and the particle size is large.
Not conducive to the modification of the electrochemical properties of the material

Method used

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  • Preparation method of multicrystal LiFePO4 powder having olivine structure
  • Preparation method of multicrystal LiFePO4 powder having olivine structure
  • Preparation method of multicrystal LiFePO4 powder having olivine structure

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preparation example Construction

[0021] The invention is a polycrystalline LiFePO with olivine structure 4 powder preparation method, the LiFePO 4 The powder is based on Fe(Ac) 2 , FeSO 4 、7H 2 O, Ba(Ac) 2 And organic acid is raw material, adopts sol-gel method to synthesize, and its specific implementation steps are:

[0022] (1)Fe(Ac) 2 Preparation: FeSO 4 ·7H 2 O is used as a source of ferrous iron, and an equimolar amount of FeSO is weighed 4 ·7H 2 O and Ba(Ac) 2 Put it in two beakers, add deionized water to dissolve it and make a solution of 0.001 ~ 1Mol / L. In FeSO 4 ·7H 2 Add 0.05-1% reduced iron powder to the O solution. Then the two solutions were mixed, stirred evenly and then centrifuged. The separated clear solution was collected and evaporated under nitrogen to give Fe(Ac) 2 powder.

[0023] (2) Weigh Fe(Ac) in molar ratio 2 :LiA:(NH 4 )H 2 PO 4 : Organic acid M=1:1:1:(1~16) (M=tartaric acid, gluconic acid or citric acid); Fe(Ac) 2 Make a solution of 0.001~0.1Mol / L, then add M...

Embodiment 1

[0029] Embodiment 1: Take by weighing 0.05 mole of Fe(Ac) 2 Put the powder into an 800mL Erlenmeyer flask, add deionized water to make a 0.1Mol / L solution, and add 0.4M organic acid to Fe(Ac) 2 in solution. Stir and place in an oven and pass nitrogen gas at a rate of 0.16 L / Min, keep the temperature at 80°C, and obtain a yellow-green clear solution after 60 Min. To this clear solution was added 0.05 molar LiAc and stirred to dissolve. Then add 0.05 mole (NH 4 )H 2 PO 4 After stirring, the system becomes a light yellow-green solution after dissolution. Put the Erlenmeyer flask into an insulation jacket, keep the temperature at 100°C and also pass through it with nitrogen. After 2.0 hours, a dark green sol was obtained, and the heating was continued to obtain a gel block. Put the gel in a graphite crucible, heat it at 600°C for 5 hours to obtain a black porous loose block, and grind it finely to obtain LiFePO4 Powder material. Figure (1) is the XRD spectrum of the materi...

Embodiment 2

[0030] Embodiment 2: Take by weighing 0.03 moles of Fe(Ac) 2 Put the powder into an 800mL Erlenmeyer flask, add deionized water to dissolve it to form a 0.05Mol / L solution, and add 0.12M organic acid. Stir and place in an oven and pass nitrogen gas at a rate of 0.16 L / Min, keep the temperature at 80°C, and obtain a green clear solution after 40 Min. To this clear solution was added 0.03 molar LiAc and stirred to dissolve. Then add 0.03 mol (NH 4 )H 2 PO 4 After stirring, the system becomes a light yellow-green solution after dissolution. Put the Erlenmeyer flask into an insulation jacket, keep the temperature at 80°C and also pass through it with nitrogen. After 3.5 hours, a dark green sol was obtained, and the heating was continued to obtain a gel block. Put the gel in a graphite crucible, heat it at 500°C for 5 hours to obtain a black porous loose block, and grind it finely to obtain LiFePO 4 Powder material. Figure (3) is the SEM image of the material.

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Abstract

A polycrystalline LiFePO4 powder with olivine structure is prepared from Fe(Ac)2, FeSO4.7H2O, Ba(Ac)2 and organic acid by the sol-gel method. Its advantages are short period, low burning temp., low energy consumption, high purity and electric conductivity, and high granularity uniformity. It is suitable for making Li-ion battery.

Description

technical field [0001] The invention belongs to the technical field of material preparation, in particular to an olivine-structured polycrystalline LiFePO 4 Powder preparation method. Background technique [0002] LiFePO 4 The material has the characteristics of cheap, non-toxic, non-hygroscopic, good environmental compatibility, rich mineral resources, high capacity (theoretical capacity is 170mAh / g, energy density is 550Wh / Kg), and good stability. It is one of the most potential alternative materials for lithium battery cathode materials. It has broad application prospects and great market demand. There are several synthetic methods: [0003] Solid-phase synthesis method: JP2000294238 mixes ferrous oxalate, lithium carbonate and diammonium hydrogen phosphate as initial materials and then calcines at high temperature for a long time. EP1193786 uses lithium phosphate and ferrous phosphate as initial materials for mixed calcining. The solid-phase synthesis material has ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B25/45C01F17/00H01M4/58
CPCY02E60/12Y02E60/10
Inventor 张中太卢俊彪唐子龙郑子山沈万慈
Owner TSINGHUA UNIV
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