1. Guangxi Key Laboratory of Information Material Guangxi Collaborative Innovation Center of Structure and Property for New Energy and Materials School of Material Science and Engineering Guilin University of Electronic Technology Guilin 541004 P. R. China
2. Center on Nanoenergy Research, School of Physical Science & Technology Guangxi University Nanning 530004 P. R. China
3. Department of Materials Science and Engineering Faculty of Engineering Shibaura Institute of Technology Tokyo 135-8548 Japan