Effects of cobalt-ion doping on the electrochemical properties of spinel lithium manganese oxide prepared via a reverse-micelle route

Monophasic, ultrafine cobalt ion-doped lithium manganate powders have been prepared via a reverse-micelle process. LiMn1.8Co0.2O4 powders were obtained after heating at 500 °C for 2 h. Both the required reaction temperature and duration for synthesizing this compound were greatly reduced, compared to those in the conventional technique involving solid-state reaction. Increasing the water to oil (W/O) volume ratio resulted in an increase in the particle size of LiMn1.8Co0.2O4 as well as the formation of impure Li2MnO3 phase. Nanosized, monophasic powders were obtained when the W/O volume ratio was 1/5. Raising the heating temperature led to an increase in the crystallite size as well as the particle size of LiMn1.8Co0.2O4. Based on the analytic results of electrochemical properties, the derived cobalt ion-doped spinel phase was confirmed to exhibit moderate discharge capacity and improved cycleability at ambient as well as elevated temperatures.