1. State Key Laboratory of Silicon Materials; Key Laboratory of Advanced Materials and Applications for Batteries of Zhejiang Province; Key Laboratory of Novel Materials for Information Technology of Zhejiang Province and School of Materials Science and Engineering; Zhejiang University; Hangzhou Zhejiang 310027 P. R. China
2. Institute for Superconducting and Electronic Materials; University of Wollongong; Wollongong NSW 2522 Australia
3. Department of Physics; Zhejiang University; Hangzhou Zhejiang 310027 P. R. China