Synthesis and electrochemical performance of NbC-modified LiFePO4/C as cathode material for lithium-ion batteries

Superconducting niobium carbide (NbC) modified LiFePO4/C samples have been synthesized for the first time through a conventional solid-state route. The crystalline structure and morphology of the as-synthesized LiFePO4/C modified with NbC are investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and their electrochemical performance are evaluated by cyclic voltammograms (CV), electrochemical impedance spectroscopy (EIS) and charge/discharge tests. It is found that the added superconducting NbC does not destroy the crystal structure of the bulk material. An analysis of the electrochemical measurements reveals that NbC-modified LiFePO4/C samples have good electric contact among particles, higher discharge capacity, stable cycle performance, good rate capability and smaller charge-transfer resistance. Therefore, the surface treatment with conductive NbC should be an effective way to improve the comprehensive performance of LiFePO4/C for lithium-ion batteries.