Synthesis and electrochemical properties of LiFePO4-graphite nanofiber composites as cathode materials for lithium ion batteries

In this paper, the influences of graphite nanofiber-antler (GNF) adding on LiFePO4 are studied by X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), cyclic voltammetry (CV), charge/discharge tests, and Ac impedance spectroscopy. In the results, the XRD patterns index to a single-phase material having an orthorhombic olivine-type structure with a space group of Pnma. The 7% GNF-added LiFePO4 demonstrates a higher conductivity than the pure LiFePO4 samples. The electronic conductivity of 7% GNF-added LiFePO4 is 5.32 × 10−3 S cm−1. The CV curves show that the 7% GNF-added LiFePO4 has higher electrochemical reactivity for lithium insertion and extraction than the pure LiFePO4 with the current is 1.65 mA and the voltage between redox peaks is 0.25 V. A discharge capacity of 131.5 mAh g−1 is achieved at a current density of 0.1 mA cm−2 with a slight decline during cycling.

► LiFePO4-Graphite nanofiber(GNF) successfully prepared by the hydrothermal method. ► The increase in electronic conductivity, and discharge capacity are determined. ► The electronic conductivity of LiFePO4-GNF (7%) is 5.32 × 10−3 S cm.−1 ► LiFePO4-GNF (7%) shows the best electrochemical performances.