Fe doped in LiCo0.6Ni0.4O2 and their electrochemical behaviour

LiCo0.6Ni0.4O2 was introduced as one of the most promising candidates for a cathode material as it had higher practical capacity compared to LiCoO2. However, it still can be improved further by using Fe as a dopant producing LiCo0.55Ni0.4Fe0.05O2 novel stoichiometry. The materials were prepared by using a self-propagating combustion method. The materials were found to be single phase and pure of the hexagonal structure and R (3) over barm space group. LiCo0.55Ni0.4Fe0.05O2 materials were annealed at fixed temperature of 800 degrees C with different annealing times to optimize the thermal process. Results showed that the Fe doped materials annealed at 800 degrees C for 24 h performs better than the undoped material in terms of first cycle capacity and capacity retention. The initial discharge capacity showed a 1.7 % improvement compared to the undoped material. Although the improvement in the first cycle is quite small, the cycle stability has improved when Fe was substituted. All of the Fe doped materials annealed at 24 h, 48 h, and 72 h had exhibited lower capacity fading (less than 30 %) compared to the undoped material (36 %) in the 20th cycle.