1. Department of Materials Science & Engineering
2. CAS Key Lab of Materials for Energy Conversion
3. University of Science and Technology of China
4. Hefei, P. R. China
5. Hefei National Laboratory for Physical Sciences at the Microscale
6. Collaborative Innovation Center of Chemistry for Energy Materials
7. and School of Chemistry and Materials Science
8. State Key Laboratory for Mesoscopic Physics
9. Department of Physics
10. Peking University
11. Beijing 100871, China