A study on the electrochemical characteristics of LiFePO4 cathode for lithium polymer batteries by hydrothermal method

Phospho-olivine LiFePO4 cathode materials were prepared by hydrothermal reaction at 150 °C. Carbon black was added to enhance the electrical conductivity of LiFePO4. LiFePO4-C powders (0, 3, 5 and 10 wt.%) were characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM). LiFePO4-C/solid polymer electrolyte (SPE)/Li cells were characterized electrochemically by charge/discharge experiments at a constant current density of 0.1 mA cm−2 in a range between 2.5 and 4.3 V vs. Li/Li+, cyclic voltammetry (CV) and ac impedance spectroscopy. The results showed that initial discharge capacity of LiFePO4 was 104 mAh g−1. The discharge capacity of LiFePO4-C/SPE/Li cell with 5 wt.% carbon black was 128 mAh g−1 at the first cycle and 127 mAh g−1 after 30 cycles, respectively. It was demonstrated that cycling performance of LiFePO4-C/SPE/Li cells was better than that of LiFePO4/SPE/Li cells.