Thermal treatment of the high-capacity integrated-structure cathode material Li2MnO3-LiMO2 (M = Mn, Ni, and Co) under a reductive H-2 atmosphere was investigated as a means to improve its rate capability when incorporated into a Lithium-ion battery (LIB). The heat-treated electrode, with a composition of Li1.12Mn0.55Ni0.145Co0.1O2, shows a better coulombic charge-discharge efficiency and a good cycleability than the pristine material. This improvement can be attributed to a reduction in the valence of some Mn ions from 4(+) to 3(+), as monitored by X-ray photoelectron spectroscopy. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3597655] All rights reserved.