Prof. Juchen Guo, Assistant Professor of Chemical and Environmental Engineering, University of California, Riverside
Rechargeable lithium-sulfur (Li-S) battery has been regarded as one of the most promising electrochemical energy storage technologies. Despite tremendous research and development efforts, current Li-S technology is still facing significant challenges from the intricate Li-S electrochemical reactions in solution phase. In this presentation, we will discuss the effect of the size of sulfur confinement on the Li-S electrochemical reaction. Our data indicate distinct change of Li-S electrochemical behaviors when sulfur is in sub-nanometer confinement in microporous carbon. We therefore propose a new solid-state Li-S electrochemical reaction mechanism enabled by Li-ion desolvation. The effects of the Li-ion solvation binding energy and structure on the proposed solid-state Li-S electrochemical reaction in the sub-nano confinement are investigated. In addition to the microporous carbon as the sulfur sub-nano confinement, narrow-diameter (< 1.0 nm) single-walled carbon nanotubes (SWNTs) are also investigated as sulfur confinement. The S@SWNTs show some unprecedented electrochemical properties, which can be attributed to the synergistic effect of sub-nano confinement and interactions between the wall of SWNTs and the confined sulfur chain.
Juchen Guo earned his Bachelor degree from Zhejiang University in 1999 and his Ph.D. from University of Maryland in 2007, both in Chemical Engineering. From 2007 to 2012, he worked as postdoctoral researcher at University of Maryland (2007 to 2011) and Cornell University (2011 to 2012). He joined the Department of Chemical and Environmental Engineering at University of California, Riverside as an Assistant Professor in summer 2012. His research interests are interfacial phenomena and evolution of material properties in electrochemical systems including Li-ion, Li-S, and multivalent ion batteries.