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Method for preparing olivine structure lithium iron phosphate

A technology of olivine structure and lithium iron phosphate, applied in chemical instruments and methods, phosphorus compounds, inorganic chemistry, etc., can solve the problems of complex preparation process, difficult industrialization, harsh conditions, etc., to improve electronic conductivity, burn The effect of low temperature and low energy consumption

Inactive Publication Date: 2006-07-12
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

This method can uniformly mix the raw materials at the molecular level, and the batch stability of the product is easy to control, but the preparation process is complicated, the conditions are harsh, and the cost is high, so it is difficult to industrialize

Method used

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  • Method for preparing olivine structure lithium iron phosphate
  • Method for preparing olivine structure lithium iron phosphate
  • Method for preparing olivine structure lithium iron phosphate

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] Example 1 After fully stirring and mixing 0.01mol / L ferrous chloride and 0.01mol / L phosphoric acid, add lithium hydroxide to control the pH value to 3.5, then add sodium peroxide to obtain a suspension, and the suspension is stirred vigorously stay in the reactor for 6 hours, then filter and wash, and the obtained filter cake (FePO 4 ) at 120°C for 12 hours. The dried precursor FePO 4 , carbon gel and lithium acetate are mixed by stoichiometry (carbon gel is calculated according to carbon content), while ensuring that the carbon gel is over 5%, after ball milling for 30min, then the mixture is put into the reduction furnace, and Ar gas is passed into it as In a protective atmosphere, heat to 500°C, 600°C, 700°C, and 800°C at a heating rate of 2°C / min and keep the temperature for 20 hours. The resulting product was analyzed by X-ray diffraction, showing that they were all LiFePO 4 , without any impurity phase, the particle size of the product obtained by SEM is about ...

Embodiment 2

[0017] Example 2 After fully stirring and mixing 0.01mol / L ammonium ferrous sulfate and 0.01mol / L phosphoric acid, add sodium hydroxide to control the pH value to 3.5, then add sodium peroxide to obtain a suspension, and the suspension is stirred vigorously stay in the reactor for 6 hours, then filter and wash, and the obtained filter cake (FePO 4 ) at 120°C for 12 hours. The dried precursor FePO 4 , carbon gel and lithium acetate are mixed by stoichiometry (carbon gel is calculated according to carbon content), while ensuring that the carbon gel is over 5%, after ball milling for 30min, then the mixture is put into the reduction furnace, and Ar gas is passed into it as Protect the atmosphere, heat up to 600°C at a heating rate of 2°C / min and keep warm for 10h, 20h, and 30h respectively. The resulting product was analyzed by X-ray diffraction, showing that they were all LiFePO 4 , without any impurity phase, the particle size of the product obtained by SEM is about 500nm. ...

Embodiment 3

[0019] Example 3 After fully stirring and mixing 2mol / L ferrous chloride and 2mol / L sodium dihydrogen phosphate, add ammonia water to control the pH value to 3.5, then add sodium peroxide to obtain a suspension, and the suspension is stirred vigorously Stay in the reactor for 6 hours, then filter and wash, the filter cake (FePO 4 ) at 120°C for 12 hours. The dried precursor FePO 4 , carbon black and lithium hydroxide are mixed stoichiometrically (carbon black is calculated according to carbon content), and at the same time ensure that the excess of carbon black is 2%, 5%, 7%, 10%, after ball milling for 30min, then put the mixture into the reduction furnace , heated to 600°C at a heating rate of 2°C / min and held for 20 hours under the protection of nitrogen gas. The resulting product was analyzed by X-ray diffraction, showing that they were all LiFePO 4 , without any impurity phase, the particle size of the product obtained by SEM is about 500nm. The obtained product was a...

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Abstract

The invention discloses a making method of chrysolite-structured ferric lithium phosphate, which is characterized by the following: mixing the bivalent Fe source compound, P source compound and oxidant at LiFePO4 chemical gauge; controlling the pH value equal to 1-8; filtering; cleaning; drying; generating about 100 nm FePO4 pioneer body; putting the mixture of FePO4 pioneer body and Li source compound and reducer in the furnace; calcining the mixture in the non-oxidized atmosphere to make LiFePO4. The invention prevents the ferrous ion from oxygenizing and difficult blending of raw material, which improves the material synthesis and property to cover the residual carbon on the LiFePO4 particle.

Description

technical field [0001] The invention belongs to the preparation of lithium ion cathode materials in the field of material preparation. Background technique [0002] LiFePO with olivine structure 4 It can reversibly intercalate and deintercalate lithium ions, and FePO obtained by delithiation 4 The volume is only 6.81% less than the original volume, so it has good cycle performance. At the same time LiFePO 4 The material has the advantages of non-toxicity, environmental friendliness, rich source of raw materials, high specific capacity (theoretical capacity is 170mAh / g, energy density is 550Wh / Kg), and high temperature stability. But the following shortcomings hinder its practical application: (1) Fe in the synthesis 2+ easily oxidized to Fe 3+ , it is not easy to obtain single-phase LiFePO 4 ; (2) lithium ions in LiFePO 4 Moderate diffusion is difficult (diffusion coefficient is 8.1×10 -18 and 2.7×10 -17 ), leading to low utilization of active materials; (3) LiFePO ...

Claims

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Application Information

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IPC IPC(8): C01B25/45
Inventor 朱炳权李新海王志兴郭华军彭文杰胡启阳张云何
Owner CENT SOUTH UNIV
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