Enhanced electrochemical properties of nano-Li3PO4 coated on the LiMn2O4 cathode material for lithium ion battery at 55 °C

The electrochemical performance of LiMn₂O₄ is improved by the surface coating of nano-Li₃PO₄ via ball milling and high-temperature heating. The Li₃PO₄-coated LiMn₂O₄ powders are characterized by X-ray diffraction and high-resolution transmission electron microscopy (HRTEM). At 55 °C, capacity retention of 85% after 100 cycles was obtained for Li/Li₃PO₄-coated LiMn₂O₄ electrode at 1C rate, while that of pristine sample was only 65.6%. The Li/Li₃PO₄-coated LiMn₂O₄ electrode also showed improved rate capability especially at high C rates. At 5C-rates, the delivered capacities of pristine and Li₃PO₄-coated LiMn₂O₄ electrodes were 80.7 mAh/g and 112.4 mAh/g, respectively. The electrochemical impedance spectroscopy (EIS) indicates that the charge transfer resistance for Li/Li₃PO₄-coated LiMn₂O₄ cell was reduced compared to Li/LiMn₂O₄ cell.