The influence of improved carbon coating layer with nanometer-sized CeO2 interconnector on the enhanced electrochemical performance of LiMnPO4

The CeO2/C hybrid coated LiMnPO4 composites are prepared via a simple and effective wet chemical process followed by heat treatment at 550 °C. The nanometer-sized CeO2 acts as an interconnector in carbon network, and its influence on the electrochemical performance is investigated in detail. The 0.25 wt.% CeO2-modified LiMnPO4/C (sample-0.25) exhibits the highest discharge capacity and the best cycle life, which can deliver an initial capacity of 139.9 mAh g−1 at 0.1C and still retain a reversible capacity of 120.4 mAh g−1 after 50 cycles (capacity retention of 86.1%). While for pristine LiMnPO4/C (sample-0), only 94.4 mAh g−1 can be obtained at the 50th cycle, corresponding to 72.9% of its initial discharge capacity (129.5 mAh g−1). Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) results confirm that an integrated and hybrid CeO2/C coating layer is formed on LiMnPO4 surface and its existence has no influence on the structure of LiMnPO4. The reason for the improved electrochemical properties of the CeO2-modified LiMnPO4/C composites has also been studied by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements.