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Process for preparing lithium ferrous phosphate coated with carbon

A lithium iron phosphate and carbon-coated technology, applied in chemical instruments and methods, phosphorus compounds, inorganic chemistry, etc., can solve the problems of cumbersome process, high processing cost, long reaction time, etc., and achieve simple process route and processing cost. Low, low material cost effect

Inactive Publication Date: 2006-08-23
SHANGHAI JIAO TONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

But the solid phase reaction is basically a solid / solid interface reaction, the reaction interface is small, so the reaction time is long, and multiple sintering is required, that is, grinding after sintering and then sintering, the process is cumbersome and the cycle is long
Even this cannot guarantee that the reaction is complete. During the high-temperature reaction, lithium phosphate Li with a high melting point may be generated. 3 PO 4 and ferrous phosphate Fe 3 (PO 4 ) 2 , the remaining unreacted impurities will deteriorate the electrochemical performance of lithium iron phosphate materials, and cause poor consistency between different batches of materials
The pure liquid phase reaction, such as the sol-gel method, is beneficial to complete the reaction, but the income is small. It is feasible to prepare samples in the laboratory, and the processing cost is high in industrial production.

Method used

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  • Process for preparing lithium ferrous phosphate coated with carbon
  • Process for preparing lithium ferrous phosphate coated with carbon

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] (1) Weigh iron phosphate, lithium acetate and ethylene glycol, the mol ratio of iron phosphate and lithium acetate is 1: 1, the mol ratio of iron phosphate and ethylene glycol is 1: 1, add distilled water, make lithium acetate and ethylene glycol The diol was dissolved, and then stirred at 60° C. for 10 hours until evaporated to dryness to obtain a lithium iron phosphate precursor.

[0026] (2) Under nitrogen protection, the lithium iron phosphate precursor was treated at 650° C. for 5 hours to obtain lithium iron phosphate.

[0027] (3) Weigh lithium ferrous phosphate and sucrose, the mass ratio of the two is 95:5, dissolve the sucrose in distilled water, heat, stir and mix until evaporated to dryness. Then, under the protection of mixed gas of nitrogen and 5% hydrogen by volume, the process was carried out at 800° C. for 3 hours to obtain carbon-coated lithium iron phosphate.

Embodiment 2

[0029] (1) Weigh iron phosphate, lithium acetate and glycerin, the mol ratio of iron phosphate and lithium acetate is 1: 1, the mol ratio of iron phosphate and glycerin is 1: 2, add distilled water, make lithium acetate and glycerin The triol was dissolved, and then stirred at 70° C. for 8 hours until evaporated to dryness to obtain a lithium iron phosphate precursor.

[0030] (2) Under the protection of a mixed gas of argon and 5% hydrogen by volume, the lithium iron phosphate precursor was treated at 500° C. for 2 hours to obtain lithium iron phosphate.

[0031] (3) Weigh lithium ferrous phosphate and glucose, the mass ratio of the two is 90:10, dissolve the glucose in distilled water, heat and stir to mix until evaporated to dryness. Then, under the protection of a mixed gas of argon and 5% hydrogen by volume, it was treated at 700° C. for 4 hours to obtain carbon-coated lithium iron phosphate.

[0032] figure 1 is the XRD spectrum of carbon-coated lithium iron phosphate,...

Embodiment 3

[0034] (1) Weigh iron phosphate, lithium acetate and urea, the mol ratio of iron phosphate and lithium acetate is 1: 1, the mol ratio of iron phosphate and urea is 1: 3, add distilled water, lithium acetate and urea are dissolved, then in Stir at 80° C. for 6 hours until evaporated to dryness to obtain a lithium iron phosphate precursor.

[0035] (2) Under the protection of the mixed gas of argon and 5% hydrogen by volume, the lithium iron phosphate precursor was treated at 700° C. for 3 hours to obtain the lithium iron phosphate.

[0036] (3) Weigh lithium ferrous phosphate and sucrose, the mass ratio of the two is 92:8, dissolve the sucrose in distilled water, heat, stir and mix until evaporated to dryness. Then, under the protection of a mixed gas of argon and 5% hydrogen by volume, it was treated at 650° C. for 2 hours to obtain carbon-coated lithium iron phosphate.

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Abstract

The preparation process of carbon coated lithium ferrous phosphate adopts ferric phosphate as one material and through reduction inside solution and high temperature heat treatment. Thus obtained carbon coated lithium ferrous phosphate has excellent crystal structure, and exhibits excellent electrochemical performance in lithium battery. It has discharge capacity at 0.2 C current up to 167 mAh / g, approaching the theoretical value 170 mAh / g. The present invention has low cost and simple technological path, and is suitable for large scale production.

Description

technical field [0001] The invention relates to a preparation method of an inorganic compound, in particular to a preparation method of carbon-coated lithium ferrous phosphate, which is used as a positive electrode material of a lithium ion battery. Background technique [0002] Lithium iron phosphate material (LiFePO 4 ) has the outstanding advantages of abundant raw materials, low cost, high specific capacity, environmental friendliness, non-toxic and harmless, and good thermal stability. Alternative materials for positive electrodes of ion batteries. At present, the preparation methods of lithium iron phosphate materials mainly include solid-phase method, liquid-phase method, microwave method and solid / liquid-phase method. [0003] Solid-phase method: Japanese patent JP2000294238 mentions that ferrous oxalate, diammonium hydrogen phosphate and lithium carbonate are ball-milled and mixed in acetone, evaporated under nitrogen, and then heat-treated at a temperature of 300...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B25/45C04B35/628H01M4/58
CPCY02E60/12Y02E60/10
Inventor 王久林王延强杨军努丽燕娜
Owner SHANGHAI JIAO TONG UNIV
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