Encapsulation of LiFePO4 by in-situ graphitized carbon cage towards enhanced low temperature performance as cathode materials for lithium ion batteries

•Several nano-sized LiFePO4 particles are encapsulated in carbon cage.•Carbon is in-situ graphitized with enhanced electronic conductivity.•The as prepared LiFePO4 exhibits notable capacity retention at −40 °C.•Rct is lowered by a factor of ~10 compared with commercial LiFePO4.

The severe capacity decay of LiFePO4 at low temperatures (≤0 °C) limits its wide applications as cathode materials for energy storage batteries. Creating comprehensive carbon network between particles with improved electronic conductivity is a well known solution to this problem. Here, a novel structured LiFePO4/C composite was prepared by a facile solid state route, in which nanosized LiFePO4 spheres were encapsulated by in-situ graphitized carbon cages. With the enhancement in electronic conductivity (2.15e−1 S cm−1), the composite presented excellent rate performance at room temperature and remarkable capacity retention at −40 °C, with charge transfer resistance much lower than commercial LiFePO4.

Graphical abstractA novel structured LiFePO4/C composite was prepared by a facile solid state route, in which nanosized LiFePO4 spheres were encapsulated by in-situ graphitized carbon cages.Figure optionsDownload full-size imageDownload as PowerPoint slide