1. State Key Laboratory of Silicon Materials; Key Laboratory of Advanced Materials and Applications for Batteries of Zhejiang Province; School of Materials Science and Engineering; Zhejiang University; Hangzhou 310027 China
2. Department of Physics and Siyuan Laboratory; Jinan University; Guangzhou Guangdong 510632 P. R. China
3. School of Physical and Mathematical Sciences; Nanyang Technological University; Singapore 637371 Singapore