Method for synthesizing graphene/carbon-coated lithium iron phosphate small-scale nanometer composite material by aniline polymerization confinement effect

Abstract

A method for synthesizing a graphene / carbon-coated lithium iron phosphate small-scale nanometer composite material by an aniline polymerization confinement effect belongs to the field of lithium ion batteries and aims to solve the problems that an existing lithium iron phosphate is small in active area and poor in electronic conductivity and the large-rate charge-discharge requirement is difficultto met. During the synthesis process, aniline is catalyzed and polymerized by ferric ions absorbed onto a graphene oxide surface in advance, the aniline reacts with phosphate radical to generate ironphosphate precipitant, two sets of reaction are simultaneously performed, the generated polyaniline wraps iron phosphate particle, the phosphate radical is prevented from being contacted with the ferric ions, the iron phosphate particle is prevented from being grown by the confinement effect, so that a small-scale nanometer precursor is obtained, a lithium source is introduced, and sintering is performed to prepare the graphene / carbon-coated lithium iron phosphate small-scale nanometer composite material. The grain size of the iron phosphate particle in the composite is smaller than 40 nanometers, carbon-coated lithium iron phosphate is anchored onto the graphene surface to form a sandwiched layer structure of an amorphous carbon layer / lithium iron phosphate / graphene layer, and the graphene / carbon-coated lithium iron phosphate small-scale nanometer composite material has favorable cycle property.

Description

technical field [0001] The invention belongs to the field of positive electrode materials for lithium ion batteries; in particular, it relates to a method for synthesizing a graphene / carbon-coated lithium iron phosphate small-scale nanocomposite material by means of aniline polymerization confinement. Background technique [0002] Lithium iron phosphate battery has the advantages of good safety, long cycle life, and environmental friendliness, and is an ideal power system for driving electric vehicles. Due to the poor electrical conductivity of lithium iron phosphate materials, the transmission of lithium ions in lithium iron phosphate crystals is difficult and the path is long, and the high-rate charge and discharge performance of lithium-ion batteries using it as the positive electrode material is poor. In terms of performance, it is still difficult to meet the fast charging requirements of pure electric vehicles and plug-in hybrid electric vehicles, which restricts the de...

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Problems solved by technology

[0003] The present invention aims to solve the technical problems of poor electrical conductivity of existing lithium iron phosphate materials, difficulty in transporting lithium ions in lithium iron phosphate crystals and a long path, and poor high-rate charge-discharge performance of lithium-ion batteries using it as the positive electrode material, and provides A method for synthesizing graphene / carbon-coated lithium iron phosphate small-scale nanocomposites by means of polyaniline confinement

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