Improvement of electrochemical performance for spherical LiFePO4 via hybrid coated with electron conductive carbon and fast Li ion conductive La0.56Li0.33TiO3

Abstract

The LiFePO4/(C + La0.56Li0.33TiO3) composites with spherical morphology are synthesized for the first time via ammonia assisted hydrothermal method. The structure and electrochemical performance of LiFePO4/(C + La0.56Li0.33TiO3) are investigated by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), charge/discharge tests and cyclic voltammetry (CV). It has been found that the hybrid coating layer composing of electron conductive C and fast Li ion conductive La0.56Li0.33TiO3 is synchronously deposited on the surface of LiFePO4 microspheres. The hybrid coating layer can be favourable for fast electron and Li+ transport, and avoid HF eroding LiFePO4 in electrolyte, thus improve the electrochemical performance. The initial discharge capacity of LiFePO4/(C + La0.56Li0.33TiO3) is 126.3 mAh g−1, the capacity retention is still as high as 98.3% even after 100 cycles at 5 C. Even at high rate of 30 C, it still reveals a high discharge capacity of 62.3 mAh g−1.