High rate electrochemical performances of nanosized ZnO and carbon co-coated LiFePO4 cathode

The high rate electrochemical performances of ZnO and carbon co-coated LiFePO4 have been studied by X-ray diffraction, high-resolution transmission electron microscope, electrochemical impedance spectroscopy, cyclic voltammetry and galvanostatic measurements. The carbon coated LiFePO4 material was prepared by a freeze-drying method, and the diffusion coefficient and exchange current of these materials were calculated from their electrochemical impedance spectroscopy. The electrode delivered a reversible capacity of about 90% of the theoretical capacity when cycled between 2.5 and 4.2 V and showed stable cycle performance at high charge/discharge rates. This study showed that the co-coating process and freeze-drying method can effectively improve the electrochemical performances of LiFePO4 materials. (C) 2010 Elsevier Ltd. All rights reserved.