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A graphene-modified lithium iron phosphate/carbon composite material and its application

A carbon composite material and graphene modification technology, applied in electrical components, battery electrodes, circuits, etc., can solve the problems of low diffusion and transmission rate of electrons and Li+, uneven battery current density, capacity attenuation, etc., to improve charging Discharge efficiency and cycle stability, improvement of high-power charge-discharge performance, effect of improved charge-discharge performance

Active Publication Date: 2011-12-28
杭州烯鲸新材料科技有限公司 +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This is mainly in LiFePO 4 During the development and development of cathode materials, some key issues have yet to be further resolved and improved, mainly including: (1) traditional LiFePO 4 The material preparation process adopts solid-state high-temperature sintering technology, which has high energy consumption and uneven particle size, resulting in uneven current density of the battery and easy capacity fading
(2) Prepared LiFePO 4 It is an insulating material and the particles are large, resulting in low diffusion and transmission rates of electrons and Li+ inside and between particles, which limits the high-rate charge-discharge performance as a positive electrode material
The lithium-ion batteries prepared by the above-mentioned several methods have achieved good performance, but the prepared composite materials cannot ensure the uniform dispersion of graphene in lithium iron phosphate, which reduces the utilization rate of graphene, and the use of high The cost of pure graphene is relatively high, which is not conducive to practical application production

Method used

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  • A graphene-modified lithium iron phosphate/carbon composite material and its application
  • A graphene-modified lithium iron phosphate/carbon composite material and its application
  • A graphene-modified lithium iron phosphate/carbon composite material and its application

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0041] The first step is to prepare graphite oxide: weigh 4g of graphite, 2g of sodium nitrate, and 92ml of concentrated sulfuric acid (95-98wt.%) in an ice bath, mix well and slowly add 12g of potassium permanganate. Then the system was raised to about 35°C and stirred for 5h. Then slowly add 184ml of distilled water to cause boiling, and continue to stir for 1h. Add 300ml of hot distilled water and 20ml of hydrogen peroxide (30wt.%), centrifuge while hot until the bubbles disappear, wash the product with dilute hydrochloric acid and distilled water until the pH is neutral, and dry part of the graphite oxide dispersion at 60°C.

[0042] The second step is to prepare graphene: Weigh the dispersion containing 100mg of graphite oxide and perform ultrasonication for 5h, then add 1ml of hydrazine hydrate for reduction, the temperature is 100°C, and the time is 24h. The product was filtered and dried at 40°C.

[0043] In the third step, solvothermal in-situ synthesis of lithium i...

Embodiment 2

[0047] The first step is the same as the first step in Example 1, preparing graphite oxide.

[0048] The second step is to weigh 200mg of graphite oxide solid, place it in a muffle furnace at 1050°C for 30s of thermal exfoliation, then weigh 100mg of thermally exfoliated graphite oxide and place it in a mixed solvent of ethanol and water for ultrasonication for 3h, and place Add 1ml of hydrazine hydrate to the dispersion liquid obtained by ultrasonication for reduction, the temperature is 80°C, and the time is 12h. The product was filtered and dried at 40°C.

[0049] Subsequent steps are the same as the third, fourth and fifth steps in Example 1. The specific capacities of the obtained products are about 160 and 111mAh / g when discharged at 0.1C and 5C, respectively.

Embodiment 3

[0051] The preparation method is basically the same as in Example 1, except that the powder calcining temperature in the fourth step is 650° C. for 2 hours. The specific capacities of the obtained products are about 158 ​​and 108mAh / g when discharged at 0.1C and 5C, respectively.

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Abstract

The invention discloses a graphene modified lithium iron phosphate / carbon composite material and its application. The graphene modified lithium iron phosphate / carbon composite material is prepared by the following steps of: using a solvent-thermal in-situ composite mode and adding a surfactant to prepare a lithium iron phosphate / graphene composite material, adding an aqueous solution of water-soluble carbon source, controlling the carbon content, carrying out drying and annealing treatments on the mixture to obtain the graphene modified lithium iron phosphate / carbon composite material. The graphene modified lithium iron phosphate / carbon composite material prepared in the invention can be used as the positive electrode active material for lithium ion cells and can be used to remarkably improve the electrochemical performance, especially the charge-discharge performance and the cycle stability of cells.

Description

(1) Technical field [0001] The invention belongs to the technical field of new energy, and in particular relates to a graphene-modified lithium iron phosphate / carbon composite material and its application in lithium ion batteries. (2) Background technology [0002] With the increasing popularity of portable electronic products and the rapid development of electric tools and electric vehicle technology, there is a more urgent demand for power supplies with high specific energy, high specific power and high safety, which greatly promotes the research and development of high specific energy batteries. develop. Since SONY first introduced lithium-ion batteries in the 1990s, the lithium-ion battery industry has developed rapidly. Among them, lithium iron phosphate is a new positive electrode material that has developed rapidly in recent years because of its high mass specific capacity. (130~140mAh / g), stable charging and discharging platform, excellent safety performance, good h...

Claims

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Application Information

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IPC IPC(8): H01M4/58H01M4/1397
CPCY02E60/122Y02E60/12Y02E60/10
Inventor 张诚苏畅卜锡丹
Owner 杭州烯鲸新材料科技有限公司
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