1. State Key Laboratory of Organic-Inorganic Composites; Beijing Key Laboratory of Electrochemical Process and Technology for Materials; Beijing University of Chemical Technology; Beijing 100029 China
2. Department of Materials Science and Engineering and A. J. Drexel Nanomaterials Institute; Drexel University; Philadelphia PA 19104 USA
3. Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education); College of Physics; Jilin University; Changchun 130012 China