To investigate the effect of Li excess and Ni substitution with Ga, powder was prepared by emulsion method and calcined at various temperatures for various times. The optimum condition for the synthesis of Li1+xNiO2 was to be calcined at 750 oC for 24 hrs in the oxygen stream. The amount of lithium excess was determined as x = 0.12 in Li1+xNiO2 composition. The optimum condition for the synthesis of LiNi1-yGayO2 was to be calcined at 700 oC for 36 hrs in the oxygen stream. The amount of Ga substitution was decided as y = 0.01 in LiNi1-yGayO2 composition. From the results of the amount of lithium excess and Ga substitution, Li1.12Ni0.99Ga0.01O2 composition was selected in this experiment. The emulsion-derived powder of this composition was synthesized at 700 oC for 36 hrs. The initial and final discharge capacities after 20 cycles were 158 and 121 mAh/g, respectively. The fading rate in discharge capacity after 20 cycles was 23%.

Keywords: LiNiO2, Lithium excess, Emulsion Method, Gallium doping, Electrochemical properties