1. Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
2. Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA 94720, USA.
3. State Key Lab of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China.
4. Department of Chemistry, University of California, Irvine, Irvine, CA, 92697, USA.
5. National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.