Rapid evaluation of charge/discharge properties for lithium manganese oxide particles at elevated temperatures

Abstract.

A microelectrode technique was applied to investigate the electrochemical properties of LiMn₂O₄ particles at elevated temperatures. Cyclic voltammograms of LiMn₂O₄ were measured after the particles were exposed to the electrolytes. This technique results in rapid and precise evaluation of the redox behavior of the materials. A significant capacity fading was observed in 1 M LiPF₆/EC+PC electrolytic solution, which indicates that both LiMn₂O₄ and LiPF₆ participate in the reaction to produce an inert material on the particle surface. Next, the capacity fading for two different BET surface area particles were compared using 1 M LiPF₆/EC+PC at 50 °C. The reaction was found not to be controlled by the surface area. Finally, a Li_1.1Mn_1.9O₄ particle was employed. The fading in discharge was ca. 10% for 50 cycles even at 50 °C, which means that the partial substitution of Mn in LiMn₂O₄ by Li substantially enhanced the capacity stability.