1. Institute of Advanced Battery Materials and Devices Faculty of Materials and Manufacturing Beijing University of Technology Beijing 100124 P. R. China
2. Key Laboratory of Advanced Functional Materials Ministry of Education Beijing University of Technology Beijing 100124 P. R. China
3. Advanced Light Source Lawrence Berkeley National Laboratory Berkeley CA 94720 USA
4. Neutron Scattering Division Oak Ridge National Laboratory Oak Ridge TN 37830 USA
5. Institute of Physics Chinese Academy of Sciences/Beijing National Laboratory for Condensed Matter Physics Beijing 100190 P. R. China