Electrochemical characteristics of LiFePO4/LiCoO2 mixed electrode for Li secondary battery

LiFePO4 cathode active material was synthesized using a solid state method and a mixed cathode was prepared by adding LiCoO2. A coin cell was prepared using the mixed cathode and its electrochemical performances were evaluated. The LiFePO4 material improved both in thermal stability and rate capability. The discharge capacity of the 5 wt.% LiCoO2-added LiFePO4 material was 139.4 mAh/g at 0.2 C rate, and it showed a capacity retention of 64.2% even at 5 C rate in comparison to 0.2 C rate. The cycle performance of the bare LiFePO4 material was excellent, but the capacity fading of 20 wt.% LiCoO2-added LiFePO4 material became significant during charge/discharge cycle. However, 5∼10 wt.% LiCoO2-added LiFePO4 material showed good thermal stability, high rate capability and good cycle performances.