LITHIUM IRON PHOSPHATE POSITIVE ELECTRODE ACTIVE MATERIAL MODIFIED BY GRAPHENE, PREPARATION METHOD AND LITHIUM ION SECONDARY BATTERY THEREOF

摘要

The invention relates to a graphene-modified lithium iron phosphate positive electrode active material and a method for preparing the same, as well as a lithium-ion secondary cell based on this positive electrode active material. The positive electrode active material is prepared by a method in which graphene or graphene oxide and lithium iron phosphate are dispersed in an aqueous solution, agitated and ultrasonicated to mix homogeneously and for a mixture, dried to obtain a lithium iron phosphate material compounded with graphene or graphene oxide, and annealed at high temperature to obtain finally a graphene-modified lithium iron phosphate positive electrode active material. When compared with conventional modified lithium cells coated with carbon or doped with conductive polymers, the lithium-ion secondary cell based on this positive electrode active material features high cell capacity, good cycling performance of charge and discharge, long life and high cycle stability, and has great utility value.