Process for preparing LiFePO4/C composite cathode material by precursor in-situ polymerization-carbothermic process

A composite cathode material, in-situ polymerization technology, applied in battery electrodes, electrical components, circuits, etc., can solve the problems of uneven carbon coating, can not greatly improve the rate performance of composite cathode materials, etc., to achieve the effect of strong conductivity

Inactive Publication Date: 2012-09-19
NANCHANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, in the above two methods, the carbon coating step is completed after the formation of lithium iron phosphate, which is easy to cause uneven carbon coating and cannot greatly improve the LiFePO 4 Rate performance of / C composite cathode materials

Method used

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  • Process for preparing LiFePO4/C composite cathode material by precursor in-situ polymerization-carbothermic process
  • Process for preparing LiFePO4/C composite cathode material by precursor in-situ polymerization-carbothermic process
  • Process for preparing LiFePO4/C composite cathode material by precursor in-situ polymerization-carbothermic process

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] 3.4509g NH 4 h 2 PO 4 and 12.12g Fe(NO 3 ) 3 9H 2 O was made into a 100mL aqueous solution, both were added to a 500mL round bottom flask, mixed with 0.5mL aniline using a pipette, and mechanically stirred evenly. Then use the dropping funnel to slowly drop into 50 mL of 5 mL of 30% H 2 o 2 , adding ammonia and HCl to adjust the pH of the solution to 1.78. After the reaction continued for 24 hours, the obtained precipitate was suction-filtered, washed twice with acetone and deionized water, and then dried at 100° C. for 2 hours by air blowing and 50° C. for 12 hours under vacuum. FePO will be obtained 4 / PAn (polyaniline) composite material and 1.2588g LiOH·H 2 O mixing, using ethanol as a dispersant in a QM-3SPO4 planetary ball mill at 300r / min for 6h. Then the ball-milled mixture was dried at 60°C and ground, then moved into a QTL1200 tube furnace, raised to 400°C at a heating rate of 5°C / min in an atmosphere of 20 mL / min high-purity Ar (99.999%) and kept fo...

Embodiment 2

[0032] 3.0195g NH 4 h 2 PO 4 and 6.757g FeCl 3 ·6H 2 O was made into 100mL aqueous solution, both were added into a 250mL round-bottomed flask, mixed with 0.6mL pyrrole using a pipette, and mechanically stirred evenly. Then use the dropping funnel to slowly drop into 50mL containing 5.7005g (NH 4 ) 2 S 2 o 8 aqueous solution, adding ammonia and HCl to adjust the pH of the solution to 1.5. After the reaction continued for 12 hours, the obtained precipitate was suction-filtered, washed once with acetone and deionized water, and then dried at 100° C. for 2 hours by air blowing and 50° C. for 12 hours under vacuum. FePO will be obtained 4 / PPy (polypyrrole) composite material and 0.9236g Li 2 CO 3 Mix, and use ethanol as a dispersant to mill in a QM-3SPO4 planetary ball mill at 200r / min for 12h. Then the ball-milled mixture was dried at 60°C and then ground, and then placed in a QTL1200 tube furnace, at 40mL / min high-purity N 2 (99.999%) in the atmosphere at a heating r...

Embodiment 3

[0034] 3.6315g (NH 4 ) 2 HPO 4 and 6.757g FeCl 3 ·6H 2 O was made into a 100mL aqueous solution, and both were added to a 250mL round bottom flask. Use a pipette to pipette 1mL of thiophene to mix, and mechanically stir evenly. Then use the dropping funnel to slowly drop into 50mL containing 4.102g (NH 4 ) 2 S 2 o 4 aqueous solution, adding ammonia water to adjust the pH of the solution to 3. After the reaction lasted for 4 hours, the obtained precipitate was suction-filtered, washed with acetone and deionized water three times respectively, and then dried at 100° C. for 2 hours by air blowing and 50° C. for 12 hours under vacuum. FePO will be obtained 4 / PTh (polythiophene) composite and 2.5505 g CH 3 COOLi·2H 2 O mixed with ethanol as a dispersant in a QM-3SPO4 planetary ball mill at 500r / min for 4h. Then the ball-milled mixture was dried at 60°C and ground, then moved into a QTL1200 tube furnace, and heated at 10 mL / min Ar and H 2 Mixed gas (volume ratio Ar:H ...

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Abstract

The invention discloses a process for preparing an LiFePO4/C composite cathode material by a precursor in-situ polymerization-carbothermic process. The process comprises that a phosphate group compound and a ferric iron source compound are dissolved in water in a mole ratio of (1-1.1):1, then an organic monomer is added, an oxidizing agent is added to oxidize and polymerize the monomer which coats a generated iron phosphate surface, the pH of a solution system is controlled to be between 1.5 and 3, a precipitate is washed, cleaned, then subjected to ball mill mixing with a lithium source and roasted in protective gas, and then the LiFePO4/C composite cathode material is obtained. Polymer which coats the iron phosphate surface is pyrolyzed and carbonized into carbon reduction ferric iron, serves as a carbon source in a roasting process and facilitates limiting of agglomeration of microscopic particles of the material. According to the LiFePO4/C composite cathode material prepared by the process, the primary particle size of the material is nanoscale, and the material is good in electrical conductivity and performance under conditions of high multiplying power and large current charging and discharging and has large specific capacity.

Description

technical field [0001] The invention relates to a preparation method of lithium iron phosphate, a positive electrode material for lithium ion batteries, in particular to a precursor in-situ polymerization-carbothermal reduction method for preparing LiFePO 4 / C composite cathode material method. Background technique [0002] LiFePO with olivine crystal structure 4 It can reversibly insert and extract lithium ions, and its advantages include: high theoretical specific capacity (about 170mAh / g); stable discharge platform around 3.4V; rich source of raw materials and low price; excellent cycle performance, stability and security etc. However, LiFePO 4 Poor intrinsic electronic conductivity and low ion diffusion coefficient restrict its charge and discharge performance under high current. In order to overcome this defect, in recent years, LiFePO modified by carbon coating 4 / C composites have been extensively studied as cathode materials for power lithium-ion batteries. Car...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/58
CPCY02E60/12Y02E60/10
Inventor 古宁宇何兴华
Owner NANCHANG UNIV
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