Electrochemical characteristics of layered LiMnCoO (2/) as a lithium-battery cathode

Ozawa, Kiyoshi*; Nakao, Yasuhiro*; Mochiku, Takashi*; Cheng, Z.*; Wang, L.*; Iwai, Hideo*; Tsuchiya, Yoshinori*; Fujii, Hiroki*; Igawa, Naoki   

A manganese-based solid solution with the composition of LiMnCoO was synthesized by a simplified coprecipitation method, and its electrochemical characteristics as a lithium-battery cathode were investigated. Rietveld refinement based on neutron diffraction data revealed that the material is assigned to an LiMnO-type structure model with a space group symmetry of 2/. In cycling of the cell in the potential range from 2.0 to 4.8 V at current densities of 30 mAhg, the discharge capacity characteristically increases from 46.3 to 196.5 mAhg as the cycle increases from 1 to 11, and a discharge capacity above 175.5 mAhg is obtained between the 23rd and 58th cycles. The cyclic voltammogram and X-ray photoelectron spectroscopy measurements showed that the manganese redox reaction is progressively activated during the first ten-odd cycles.