Preparation and Investigation on Lattice Distortion and Electrochemical Performances of Li0.95Na0.05FePO4/C

Na+ doped sample Li0.95Na0.05FePO4 was prepared through solid state method. Structure characterization shows Na+ is successfully introduced into the LiFePO4 matrix. Scanning electron microscopy shows the particle size mainly ranges in 1-3 um. X-ray diffraction Rietveld refinement demonstrates lattice distortion with an increased cell volume. As one cathode material, it has a discharge capacity of 150 mAh/g at 0.1 C rate. The material exhibits a capacity of 109 and 107 mAh/g at 5 and 7.5 C respectively. When cycled at 1 and 5 C, the material retains 84% (after 1000 cycles) and 86% (after 350 cycles) of the initial discharge capacity respectively indicating excellent structure stability and cycling performance. Na+ doping enhances the electrochemical activity especially the cycle performance effectively.