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Making method for nano LiFePO4-carbon composite cathode material

A technology of lithium iron phosphate and positive electrode materials, applied in the direction of electrode manufacturing, phosphorus compounds, chemical instruments and methods, etc., can solve the problems of difficult control of product purity, influence on rate performance, complicated preparation process, etc., and achieve excellent cycle stability , low price, simple process route

Inactive Publication Date: 2008-01-16
SHANGHAI INST OF MICROSYSTEM & INFORMATION TECH CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the electrical conductivity of this material is very poor, and it can only be charged and discharged at a very small rate at room temperature, which affects its rate performance; in addition, the preparation process usually uses Fe 2+ As an iron source, the price is lower than that of Fe 3+ The salt is high and requires multi-step grinding and heat treatment processes, the preparation process is more complicated, and the product purity is not easy to control, thus increasing the cost, which hinders its application in practical lithium-ion batteries

Method used

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  • Making method for nano LiFePO4-carbon composite cathode material
  • Making method for nano LiFePO4-carbon composite cathode material

Examples

Experimental program
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Effect test

Embodiment 1

[0019] 1) Weigh 0.5molFe(NO 3 ) 3 9H 2 O is dissolved in the organic solvent of ethylene glycol methyl ether, fully mixed and stirred at room temperature, is mixed with 1.5mol / L solution, takes by weighing 0.5mol lithium dihydrogen phosphate and excessive sucrose (the consumption of sucrose makes the carbon content in the product be 6%), add 50ml of distilled water to dissolve it, then mix with ethylene glycol methyl ether solution to form a uniformly dispersed sol, and stir and evaporate at 70°C for 6 hours to form a gel, and finally vacuum dry to a dry gel to obtain phosphoric acid Lithium iron precursor;

[0020] 2) Put the lithium iron phosphate precursor into a tubular resistance furnace, and pretreat it at 300°C for 5 hours under the protection of an argon gas flow with a flow rate of 5-50 liters / min;

[0021] 3) Grinding the pretreated mixture evenly, heat-treating at 725° C. for 10 hours under an argon atmosphere, and cooling down to room temperature to obtain a car...

Embodiment 2

[0026] 1) Weigh 0.5molFe(NO 3 ) 3 9H 2O is dissolved in the organic solvent of propylene glycol methyl ether, fully mixes and stirs at room temperature, is mixed with 1.5mol / L solution, takes by weighing 0.5mol potassium dihydrogen phosphate and excessive sucrose (the consumption of sucrose makes carbon content be 6% in the product) ), add 50ml of distilled water to dissolve it, then blend with propylene glycol methyl ether solution to form a uniformly dispersed sol, and stir and evaporate at 70°C for 6 hours to form a gel, and finally vacuum dry to dry gel to obtain lithium iron phosphate Precursor;

[0027] 2) Put the lithium iron phosphate precursor into a tubular resistance furnace, and pretreat it at 300°C for 5 hours under the protection of an argon gas flow with a flow rate of 5-50 liters / min;

[0028] 3) Grinding the pretreated mixture evenly, heat-treating at 725° C. for 10 hours under an argon atmosphere, and cooling down to room temperature to obtain a carbon-coa...

Embodiment 3

[0030] 1) Weigh 0.5mol ferric citrate and dissolve it in ethylene glycol methyl ether organic solvent, fully mix and stir at room temperature, and prepare a 1.5mol / L solution, weigh 0.5mol lithium dihydrogen phosphate and excess sucrose (sucrose The amount of carbon content in the product is 6%), add 50ml of distilled water to dissolve it, then mix with ethylene glycol methyl ether solution to form a uniformly dispersed sol, and stir and evaporate at 60°C for 6 hours to form a gel, and finally vacuum Dried to xerogel to obtain lithium iron phosphate precursor;

[0031] 2) Put the lithium iron phosphate precursor into a tubular resistance furnace, and pretreat it at 300°C for 5 hours under the protection of an argon gas flow with a flow rate of 5-50 liters / min;

[0032] 3) Grinding the pretreated mixture evenly, heat-treating at 725° C. for 10 hours under an argon atmosphere, and cooling down to room temperature to obtain a carbon-coated nano-lithium iron phosphate composite ma...

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Abstract

The invention relates to a method for preparing a nano-ferrous lithium phosphate-carbon compound positive material, which is characterized in that based on the ethers organic solvent system and by a sol-process of precursor materials, the mixture at the molecular level of Fe3+, Li+1 and PO42- is realized, and then the technology of low-temperature sintering is used to prepare. Ferrous lithium phosphate in the prepared compound material is in an olivine type with carbon wrapping outside in an amorphous form and the particle size of 45-60nm, and a stable charging and discharging voltage platform at 3.4V is provided, and the charging-discharging capacity under the current of 2C can reach to 133mAh / g. The invention is characterized by simple technique, environment-friendly performance and so on.

Description

technical field [0001] The invention relates to a preparation method of a lithium ion battery positive electrode composite material, in particular to a preparation method of a nanometer lithium iron phosphate-carbon composite positive electrode material. It belongs to the field of lithium ion battery materials. Background technique [0002] At present, the research on cathode materials for lithium-ion batteries mainly focuses on potassium-containing transition metal oxides of Co, Ni, and Mn. LiCoO 2 It is the only positive electrode material commercialized on a large scale. The research is relatively mature and the comprehensive performance is excellent. However, the preparation cost of the material is high, and the thermal stability is poor, the toxicity is high, and there are certain safety problems. It is necessary to find high-performance and low-cost materials. new material to replace it. LiNiO 2 It has high discharge specific capacity and low preparation cost, but ...

Claims

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Application Information

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IPC IPC(8): H01M4/04H01M4/58C01B25/45C01B31/00C04B35/624B01J19/00B22F1/02H01M4/583
CPCY02E60/12Y02E60/10
Inventor 刘辉解晶莹王可
Owner SHANGHAI INST OF MICROSYSTEM & INFORMATION TECH CHINESE ACAD OF SCI
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