1. Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-hiroshima, Hiroshima 739-8527, Japan
2. Battery Materials Research Laboratory, Kurashiki Research Center, Kuraray Co., Ltd., 2045-1 Sakazu, Kurashiki, Okayama 710-0801, Japan