Lithium iron phosphate composite material coated with ternary carbon source and preparation method of material

A technology of lithium iron phosphate and composite materials, which is applied in electrical components, electrochemical generators, battery electrodes, etc., can solve the problems of low conductivity, low lithium ion diffusion coefficient and low tap density of lithium iron phosphate materials. , to achieve the effect of shortening the molecular reorganization process, solving the problem of easy reunion and difficult reunion

Active Publication Date: 2014-05-14
TECHNICAL INST OF PHYSICS & CHEMISTRY - CHINESE ACAD OF SCI
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  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0011] The purpose of the present invention is to overcome the defects of poor electrical conductivity and low tap density of lithium ferrous phosphate in the prior art, and provide a lithium ferrous phosphate composite material coated with a ternary carbon source and a preparation method thereof. The present invention is based on different According to the characteristics of pyrolysis characteristics, carbonization degree, dispersion form, residual carbon structure and reduction activity of carbon source, according to the process and reaction process of preparing lithium iron phosphate by carbothermal reduction method, a ternary carbon source coated lithium iron phosphate is proposed. The modification method solves the problems of low conductivity, low diffusion coefficient of lithium ions, and low tap density of lithium iron phosphate materials

Method used

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  • Lithium iron phosphate composite material coated with ternary carbon source and preparation method of material
  • Lithium iron phosphate composite material coated with ternary carbon source and preparation method of material
  • Lithium iron phosphate composite material coated with ternary carbon source and preparation method of material

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Embodiment 1

[0056] The preparation of embodiment 1 graphene oxide

[0057] 1) Under the condition of ice-water bath (0° C.), mix 2 g of graphite and 2 g of sodium nitrate, and slowly add 100 ml of 98% concentrated sulfuric acid while stirring. After fully stirring for 1 h, slowly add 10 g of potassium permanganate, and add 5 times, 2 g each time. After adding potassium permanganate, fully react for 1h.

[0058] 2) Raise the temperature to 35° C., and react for 2 hours under continuous stirring to obtain a black viscous slurry A.

[0059] 3) Slowly add 160ml of deionized water dropwise into the black viscous slurry A under constant stirring and rapid stirring, and reddish-brown gas overflows, so ensure that the experiment is carried out in a fume hood. After the reaction is complete, 150 ml of deionized water is added therein to dilute the acidity of the solution to obtain a khaki-yellow slurry B.

[0060] 4) Heat the khaki slurry B to 95°C, slowly add 120ml of H while stirring 2 o 2(...

Embodiment 2

[0063] The preparation of embodiment 2 graphene oxide

[0064] 1) Under the condition of ice-water bath (0° C.), mix 5 g of graphite and 5 g of sodium nitrate, and slowly add 250 ml of 98% concentrated sulfuric acid while stirring. After fully stirring for 1 h, slowly add 30 g of potassium permanganate, and add 15 times, 2 g each time. After adding potassium permanganate, fully react for 2.5h.

[0065] 2) Raise the temperature to 35° C., and react for 5 hours under constant stirring to obtain a black viscous slurry A.

[0066] 3) Slowly add 400ml of deionized water dropwise to the black viscous slurry A under continuous rapid stirring, and reddish-brown gas overflows, so ensure that the experiment is carried out in a fume hood. After the reaction is complete, 500 ml of deionized water is added therein to dilute the acidity of the solution to obtain a khaki-yellow slurry B.

[0067] 4) Heat the khaki slurry B to 95°C, slowly add 300ml of H while stirring 2 o 2 (mass fracti...

Embodiment 3 3

[0070] Example 3 Preparation of lithium iron phosphate composite material coated with ternary carbon source

[0071] Step 1. Homogenization of precursor slurry:

[0072] According to the molar ratio of stoichiometric ratio Fe, P, Li is 1: 1: 1, take by weighing iron phosphate, lithium hydroxide, take by weighing 1.5 grams of graphene according to every mole of iron source, take by weighing 9 grams of starch according to every mole of iron source, Take 7 grams of thermosetting phenolic resin (model PF-2426) according to every mole of iron source, and the weight content of carbon in the lithium iron phosphate composite material coated by the final ternary carbon source is 6%;

[0073] Ultrasonically disperse graphene in water until the peeling is complete to obtain graphene slurry, then disperse iron phosphate in the above graphene slurry, ball mill the slurry, then dissolve lithium hydroxide, starch in water, and PF-2426 in ethanol, and then sequentially added to the above-men...

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Abstract

The invention provides a lithium iron phosphate composite material coated with a ternary carbon source and a preparation method of the material and belongs to the technical field of positive materials for lithium ion cells, aiming at the defects of poor conductivity and low tap density of lithium iron phosphate. The invention provides a modification method of the lithium iron phosphate composite material coated with the ternary carbon source according to the characteristics including pyrolysis characteristics, carbonization degrees, dispersion manners, residual carbon structures, reduction activity and the like of different carbon sources, based on a process and reaction process of preparing the lithium iron phosphate by using a carbon heat reduction method; micro-molecular water-soluble organic matters, high-molecular polymers, graphene compounds, iron source compounds, phosphorus source compounds and lithium source compounds are ball-grinded and homogenized and then are dried to prepare a composite precursor; then the composite precursor is sintered to obtain the lithium iron phosphate composite material. According to the lithium iron phosphate composite material coated with the ternary carbon source, the problems that the conductivity of the lithium iron phosphate composite material is low, the lithium ion diffusion coefficient is low, the tap density is low, and the like are solved.

Description

technical field [0001] The invention belongs to the technical field of cathode materials for lithium ion batteries, and in particular relates to a lithium iron phosphate composite material coated with a ternary carbon source and a preparation method thereof. Background technique [0002] Lithium iron phosphate (LiFePO 4 ) as a cathode material for lithium-ion batteries has the advantages of excellent safety, high theoretical capacity, stable discharge platform, low price, and environmental friendliness. Lithium is one of the widely used materials. However, due to its own structural factors, lithium iron phosphate leads to its low electronic conductivity (~10 -9 S / cm) and ionic conductivity (~10 -5 S / cm), especially when the battery is charged and discharged at a high current, the battery is significantly lower than that at a low current. The actual measurement of lithium ions in LiFePO 4 and FePO 4 The diffusion coefficients were 1.8×10 -14 cm 2 / s and 2×10 -16 cm 2...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/58H01M4/62H01M4/1397
CPCH01M4/1397H01M4/366H01M4/5825H01M4/625H01M10/0525Y02E60/10
Inventor 杨岩峰梅日国宋晓睿张敬杰宋广智
Owner TECHNICAL INST OF PHYSICS & CHEMISTRY - CHINESE ACAD OF SCI
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