1. Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education); State Key Laboratory of Superhard Materials; College of Physics; Jilin University; Changchun 130012 China
2. State Key Laboratory of Superhard Materials; Jilin University; Changchun 130012 China
3. Institute for Applied Materials (IAM); Karlsruhe Institute of Technology (KIT); D-76344 Eggenstein-Leopoldshafen Germany