In-situ synthesizing superior high-rate LiFePO4/C nanorods embedded in graphene matrix

Abstract

To overcome the detrimental effects of LiFePO4 on the tap density and volumetric energy density accompanied by conventional carbon-based additives, C-LiFePO4/graphene was successfully prepared via hydrothermal synthesis, followed by heat treatment, and by substitution of superior conductive graphene nanosheets for some conventional carbon. The reduction of graphite oxide and the synthesis of LiFePO4 were carried out simultaneously in mixed ethylene glycol/water medium, facilitating desirable compatibility and architecture of LiFePO4 particles and graphene nanosheets. Due to the synergism of thin carbon coating and graphene matrix with low fraction on the basis of complementary advantages, C-LiFePO4/graphene exhibits superior high-rate performance and favorable energy density, which with a unique structural and geometrical feature that LiFePO4/C nanorods embedded in a matrix built of interweaved graphene nanosheets. The dual coatings exert a significantly energetic impact on the electronic conductivity and lithium ion transport, thus novel composite presented excellent electrochemical properties, which was achieved with reversible capacities of 100 mAh/g at 20C and 80 mAh/g at 50C, while preserving a high tap density of 1.76g/cm3.