Graphene film-in-situ-coated lithium iron phosphate positive electrode material and preparation method therefor

A technology of lithium iron phosphate and cathode materials, which is applied in the field of composite materials, can solve the problems of uneven coating, agglomeration, and poor performance of coating materials, and achieve the effects of low cost, increased energy density, and inhibited growth

Active Publication Date: 2017-03-15
HUNAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] In order to solve technical problems such as agglomeration easily caused by physical mixing of graphene and lithium iron phosphate in the prior art, uneven coating of graphene, and poor perfo

Method used

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  • Graphene film-in-situ-coated lithium iron phosphate positive electrode material and preparation method therefor
  • Graphene film-in-situ-coated lithium iron phosphate positive electrode material and preparation method therefor
  • Graphene film-in-situ-coated lithium iron phosphate positive electrode material and preparation method therefor

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0049] 1): Weigh ferrous sulfate heptahydrate (molecular formula FeSO 4 ·7H 2 (O) 41.7g, hexamethylenediamine tetramethylene phosphonic acid (molecular formula C 10 h 28 N 2 o 12 P 4 ) 18.5g, lithium hydroxide monohydrate (molecular formula LiOH·H 2 (0) 18.8g, dissolved in 500ml deionized water successively, magnetically stirred until a transparent solution A was formed, and set aside.

[0050] 2): Weigh 1.2 g of graphene oxide (1-2 layers) powder, and ultrasonically disperse it in 100 ml of deionized water at 20-45° C. to obtain dispersion solution B (pH 6-8).

[0051] 3): Mix solution A and dispersion solution B, and under the protection of argon, stir and disperse at high speed to obtain solution C.

[0052] 4): Quickly transfer solution C to a 1000ml stainless steel reactor, react at 185°C for 8 hours, wash with absolute ethanol and deionized water after cooling until no SO 4 2- , suction filtration, and vacuum drying at 70°C to obtain precursor powder.

[0053] ...

Embodiment 2

[0057] 1): Weigh respectively ferrous sulfate heptahydrate (molecular formula FeSO 4 ·7H 2 (O) 125.1g, two 1,6-hexamethylenetriaminepentamethylene phosphonic acid (molecular formula C 17 h 44 o 15 N 3 P 5 )61.7g, lithium hydroxide monohydrate (molecular formula LiOH·H 2 (0) 56.4g, dissolved in 1000ml deionized water successively, magnetically stirred until a transparent solution A was formed, and set aside.

[0058] 2): Weigh 2.84g of graphene oxide (3-5 layers) powder and ultrasonically disperse it in 300ml of deionized water at 20-45°C to obtain dispersion solution B (pH6-8).

[0059] 3): Mix the solution A and the dispersion solution B, under the protection of argon, mix evenly to obtain the solution C.

[0060] 4): Quickly transfer solution C to a 2000ml stainless steel reactor, react at 200°C for 6h, wash with absolute ethanol and deionized water after cooling until there is no SO 4 2- , suction filtration, and vacuum drying at 70°C to obtain precursor powder.

...

Embodiment 3

[0064] 1): Weigh respectively ferrous sulfate heptahydrate (molecular formula FeSO 4 ·7H 2 O) 83.4g, aminomethylphosphonic acid (molecular formula CH 6 NO 3 P) 33.3g, lithium hydroxide monohydrate (molecular formula LiOH·H 2 O) 37.6g, and dissolved in 700ml deionized water successively, magnetically stirred until forming transparent solution A, for subsequent use.

[0065] 2): Weigh 1.58g of graphene oxide (6-9 layers) powder and ultrasonically disperse it in 200ml of deionized water at 20-45°C to obtain dispersion solution B (pH6-8).

[0066] 3): Mix solution A and dispersion solution B, and under the protection of argon, uniformly disperse to obtain solution C.

[0067] 4): Quickly transfer solution C to a 1500ml stainless steel reaction kettle, react at 220°C for 5h, wash with absolute ethanol and deionized water after cooling until there is no SO 4 2- , suction filtration, and vacuum drying at 70°C to obtain precursor powder.

[0068] 5): Put the precursor powder in...

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Abstract

The invention discloses a graphene film-in-situ-coated lithium iron phosphate positive electrode material and a preparation method therefor. A lithium source, an iron source, a chelated phosphorus source and graphene oxide are used as raw materials to prepare precursor powder by a hydrothermal reaction; and then the obtained precursor powder is sintered under atmosphere protection to obtain the in-situ grown graphene film-coated nanometer graphene film/lithium iron phosphate material with a core-shell structural characteristic. In addition, the invention also provides an application of the nanometer graphene film/lithium iron phosphate composite material prepared by the preparation method in a positive electrode of a lithium ion battery. In the product prepared by the preparation method, graphene is grown on and coats the surface of the lithium iron phosphate in an in-situ manner to form the graphene film/lithium iron phosphate positive electrode material, with an in-situ synthesis reaction, a nanometer effect and the core/shell structure characteristic, for the lithium ion battery; by virtue of the positive electrode material, the energy density, the high-rate charge-discharge characteristics and the cycling performance of the lithium ion battery are improved; and meanwhile, the adopted raw materials are low in cost and the process route is simple, so that the lithium iron phosphate positive electrode material is suitable for large-scale industrial production and application.

Description

technical field [0001] The invention belongs to the technical field of battery electrode materials, and in particular relates to a method for uniformly surface-coating a lithium iron phosphate material with a graphene film layer in situ and a composite material prepared by the preparation method. Background technique [0002] With the rapid development of the national economy, the automobile industry is facing energy and environmental issues, which provides unprecedented opportunities for the development of electric vehicles and the application of lithium-ion batteries. Lithium-ion power batteries are one of the commonly used batteries for electric vehicles. Lithium iron phosphate (LiFePO 4 ) is an optional cathode material for a new generation of lithium-ion power batteries. The P-O bond in lithium iron phosphate crystal is stable and difficult to decompose. Even at high temperature or overcharge, it will not collapse and generate heat or form strong oxidizing substances ...

Claims

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Application Information

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IPC IPC(8): H01M4/36H01M4/583H01M4/62H01M4/58H01M10/0525C01B25/26C01B25/45C01B25/37
CPCC01B25/26C01B25/375C01B25/45H01M4/366H01M4/5825H01M4/583H01M4/625H01M10/0525Y02E60/10
Inventor 何莉萍查文珂陈大川
Owner HUNAN UNIV
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