1. Key
Laboratory of Physics and Technology for Advanced Batteries (Ministry
of Education), College of Physics, Jilin University, Changchun 130012, P. R. China
2. College
of Applied Science, Harbin University of Science and Technology, Harbin 150080, P. R. China
3. State
Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, P. R. China