1. Department of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina 27708, United States
2. Department Structure and Dynamics of Energy Materials, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 14109 Berlin, Germany
3. IBM T. J. Watson Research Center, Yorktown Heights, New York, New York 10598, United States
4. Department of Chemistry, Duke University, Durham, North Carolina 27708, United States