Event
Special Energy Seminars
Monday, March 7, 2016
3:00 p.m.-5:00 p.m.
1110 Kim Engineering Building
Amanda McCrum
301 405 9378
amccrum@umd.edu
3PM
“A Close Look at the Lithium-Sulfur Electrochemical Process”
Juchen Guo
Lecture Abstract:
Lithium-sulfur battery has long been regarded as one of the most promising electrochemical energy storage technologies. However, the recent progress of Li-S battery development has become stale. The Li-S electrochemical process at the sulfur cathode intricately involves many simultaneous reactions, therefore designing and fabricating sulfur cathodes guided with conventional wisdom are not effective to deliver desirable battery performance. In this presentation, we will take a close look at the Li-S process at the sulfur cathode, which can potentially lead to new strategies to improve sulfur cathodes. At first, we will present a new solid-state Li-S electrochemical reaction mechanism enabled by sub-nano confinement. Our results demonstrate a clear correlation between the size of sulfur confinement and the resulting Li-S electrochemical mechanisms. In particular, when sulfur is confined within sub-nano pores, we observe identical lithium-sulfur electrochemical behavior in both ether and carbonate electrolytes. Taken together, our results highlight the critical importance of sub-nano confinement effects on controlling solid-state reactions in Li-S electrochemical systems. Secondly, we will analyze the requirement for a realistic Li-S battery to surpass the state of the art Li-ion batteries on specific capacity. Based on the analysis, we will present a strategy to achieve such goal by fine-tuning the carbon host porous structure and binder chemistry.
Speaker Biography:
Juchen earned his Bachelor degree at Zhejiang University in 1999 and his Ph.D. at University of Maryland in 2007, both in Chemical Engineering. From 2007 to 2012, he worked as postdoctoral researcher at UMD (2007 to 2011) and Cornell University (2011 to 2012). He has been an Assistant Professor in the Department of Chemical and Environmental Engineering at University of California, Riverside since summer 2012. His current research interests are interfacial phenomena and evolution of material properties in electrochemical systems including Li-ion, Li-S, and multivalent ion batteries.
4pm
"New Approaches for Next Generation Battery Materials"
Dr. Candace Chan, Arizona State University
Lecture Abstract:
In the last few years, nanostructured materials have been used to improve the charge storage capacity and cycling stability of materials used as electrodes in lithium-ion batteries, with great improvements made in anodes. However, despite this impressive proof-of-principle, nanostructured silicon can still suffer from degradation over long cycling times due to several reasons such as collapse of the nanostructure, increased porosity, structural instability, and insufficient surface passivation. Furthermore, achieving similar improvements in cathodes still remains a significant challenge and completely new ways to discover and develop improved cathodes are needed. Additionally, the safety issues related to the flammability of the electrolyte used in lithium-ion batteries are increasing becoming more important and must be addressed.
Speaker Biography:
Candace K. Chan joined the faculty in materials science and engineering at Arizona State University in August 2011 as an assistant professor and is also a member of the graduate faculty in the department of chemistry. Her research group is designing and studying the unique properties of nanostructured materials for applications in electrochemical energy storage, photocatalysis, and water treatment. She was nominated to the National Academy of Engineering’s 2014 Japan-America Frontiers of Engineering Symposium and was the recipient of the Faculty Achievement: Young Investigator and co-recipient of the Faculty Achievement: Best Innovation Awards from ASU in 2014. She is also a recipient of a Humboldt Fellowship from the Alexander von Humboldt Foundation and a CAREER award from the NSD Division of Materials Research Ceramics program.
Prior to joining ASU, Candace was a Miller Postdoctoral Fellow at UC Berkeley in the Department of Chemistry. She received her Ph.D. in Chemistry from Stanford in 2009. As a graduate student, she was a NSF Graduate Fellow, Stanford Graduate Fellow, and winner of the MRS Graduate Student Award (Silver) and TMS Ross N. Tucker Award in Electronic Materials. She obtained a B.S. in chemistry from Rice University in 2005 and spent several summers conducting undergraduate research at Los Alamos and Lawrence Berkeley National Labs.
