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Preparation method of lithium iron phosphate/graphene composite material

A technology of lithium iron phosphate and composite materials, which is applied in the direction of electrical components, battery electrodes, circuits, etc., can solve the problems of reducing the energy density and tap density of materials, and there is no effective mixing of graphene and lithium iron phosphate, so as to improve the rate performance , Improve the effect of large rate discharge capacity and high conductivity

Inactive Publication Date: 2017-09-12
CHANGSHA UNIVERSITY OF SCIENCE AND TECHNOLOGY +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, carbon coating will reduce the energy density and tap density of the material, and graphene is expected to improve the above shortcomings due to its advantages such as good conductivity, small mass, and large specific surface area, and obtain a positive electrode material with a complete structure and high energy density.
But so far there is no way to effectively mix graphene and lithium iron phosphate

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] Take by weighing 40mg graphene and 23.915g riboflavin sodium phosphate and join in 40ml deionized water, then utilize bath type ultrasonic and mechanical stirring device to disperse the graphene mixed solution, obtain the graphene dispersion after the dispersing time of 5h; Dissolve 9.7287g of ammonium citrate, 5.2554g of lithium acetate, and 20.5255g of ferric nitrate in 30ml of deionized water, and then add them to the graphene dispersion in sequence at room temperature, adjust the pH to 6 at 50°C, and then transfer them into the autoclave In the process, react at a temperature of 180°C for 2 hours and then filter to obtain a lithium iron phosphate / graphene composite material; put the obtained lithium iron phosphate / graphene, 0.9465g glucose and ethanol into a ball mill for ball milling for 6 hours, and the ball-to-material ratio is 1:6 , adjusting the ball milling rate to 200rpm, drying at 35°C after ball milling, and calcining at a constant temperature of 750°C for 1...

Embodiment 2

[0020] Take by weighing 40mg graphene and 23.915g riboflavin sodium phosphate and join in 40ml deionized water, then utilize bath type ultrasonic and mechanical stirring device to disperse the graphene mixed solution, obtain the graphene dispersion after the dispersion time of 7.5 h; Dissolve 9.7287g of ammonium citrate, 5.2554g of lithium acetate, and 20.5255g of ferric nitrate in 30ml of deionized water, and then add them to the graphene dispersion in sequence at room temperature, adjust the pH to 7 at 50°C, and then transfer to the high-pressure reaction In the kettle, react at a temperature of 180° C. for 3 h and then filter to obtain a lithium iron phosphate / graphene composite material; the obtained lithium iron phosphate / graphene, 0.9465 g glucose and ethanol are dropped into a ball mill for ball milling for 6 h, and the ball-to-material ratio is 1: 6. Adjust the ball milling rate to 200rpm, dry at 35°C after ball milling, and then calcinate at a constant temperature of 7...

Embodiment 3

[0022] Take by weighing 80mg graphene and 23.915g riboflavin sodium phosphate and join in 40ml deionized water, then utilize bath type ultrasonic and mechanical stirring device to disperse the graphene mixed solution, obtain the graphene dispersion after the dispersing time of 10 h; Dissolve 9.7287g of ammonium citrate, 5.2554g of lithium acetate, and 20.5255g of ferric nitrate in 30ml of deionized water, and then add them to the graphene dispersion in sequence at room temperature, adjust the pH to 8 at 50°C, and then transfer to the high-pressure reaction In the kettle, react at a temperature of 180° C. for 4 h and then filter to obtain a lithium iron phosphate / graphene composite material; the obtained lithium iron phosphate / graphene, 0.9465 g glucose and ethanol are dropped into a ball mill for ball milling for 6 h, and the ball-to-material ratio is 1: 6. Adjust the ball milling rate to 200rpm, dry at 35°C after ball milling, and then calcinate at a constant temperature of 75...

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Abstract

The invention discloses a preparation method of a lithium iron phosphate / graphene composite material. The preparation method comprises the following steps of adding graphene and riboflavin sodium phosphate into a solvent; treating by ultrasonic waves, stirring, and uniformly dispersing; respectively dissolving a complexing agent, a lithium source compound and an iron salt compound into a solution, then sequentially adding into a graphene dispersing liquid, and reacting, so as to obtain the lithium iron phosphate / graphene composite material; uniformly mixing the obtained lithium iron phosphate / graphene composite material and a carbon source in a ball milling way, drying, and calcining for 3 to 24h at constant temperature of 600 to 850 DEG C under the inert gas protection atmosphere, so as to obtain the graphene-modified lithium iron phosphate / carbon composite material. The preparation method has the advantage that the riboflavin sodium phosphate is dispersed into the graphene to form a surfactant, and can also be used as a phosphor source in the generation process of the lithium iron phosphate. The prepared graphene-modified lithium iron phosphate / carbon composite material can be used as the cathode material of a lithium ion battery, so that the electrochemical properties, particularly the cyclic stability at high rate, of the battery can be obviously improved.

Description

technical field [0001] The invention belongs to the technical field of preparation of positive electrode materials of lithium ion batteries, and in particular relates to a preparation method of lithium iron phosphate / graphene composite material. Background technique [0002] Currently known cathode materials for lithium-ion batteries include lithium cobalt oxide (LiCoO 2 ), lithium iron phosphate (LiFePO 4 ), lithium manganate (LiMn 2 o 4 ), lithium nickel cobalt oxide (LiNi x co 1-x o 2 ), lithium nickel cobalt manganese oxide (LiNi 1 / 3 co 1 / 3 mn 1 / 3 o 2 ) and other materials. Compared with other cathode materials LiFePO 4 It has the advantages of high discharge specific capacity (3.47V), relatively stable discharge platform, good cycle stability, thermal stability and low price. But LiFePO 4 The defects of low electronic conductivity, low packing density and low ion diffusion efficiency make LiFePO 4 The rate performance is poor, which greatly limits the LiFe...

Claims

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Application Information

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IPC IPC(8): H01M4/36H01M4/58H01M4/62
CPCH01M4/364H01M4/5825H01M4/625Y02E60/10
Inventor 陈召勇张曾罗丁段军飞
Owner CHANGSHA UNIVERSITY OF SCIENCE AND TECHNOLOGY
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