1. Institute of Advanced Battery Materials and Devices Faculty of Materials and Manufacturing Beijing University of Technology Beijing 100124 P. R. China
2. Key Laboratory of Advanced Functional Materials Ministry of Education Beijing University of Technology Beijing 100124 P. R. China
3. Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100190 P. R. China
4. Chinese Acad Sci, Shanghai Institute of Microsystem and Information Technology State Key Laboratory of Functional Materials for Informatics Shanghai 200050 P. R. China
5. Fudan University Department of Materials Science Shanghai 200433 P. R. China