Abstract:
Lithium-sulfur (Li-S) battery is a promising rechargeable battery system that has both high theoretical capacity and energy density. Moreover, sulfur is inexpensive and nontoxic, making Li-S suitable for large-scale energy storage applications. However, major hurdles exist. On the cathode side, sulfur lithiation is a multi-step electrochemical process involving different lithium polysulfide (Li2Sn, 1≦n≦8) inter-mediates. The long-chain polysulfides are highly soluble in the aprotic organic electrolyte, which is strongly linked to the deterioration of several key performance indexes, such as coulombic efficiency, self-discharge, capacity fading.
Furthermore, the starting S cathode and lithiated end product Li2S are both insulating, and the rate performance of Li-S batteries is another challenge. High rate performance has relied mainly on the specially tailored nanostructured conductive carbon materials, but it is expected to substantially increase manufacturing and material costs for the electrode.
On the anode side, major challenges for Li metal anodes are rooted in the dendritic Li deposits on metal substrates. Li dendrite growth can cause low Columbic efficiency, infinite volume expansion, accelerated electrolyte decomposition, and even penetration of the separator to trigger short-circuit and thermal runaway.
In this talk, recent research activities in the Energy Materials Laboratory at ChE, NTU dealing with the aforementioned critical issues of Li-S batteries will be presented
Brief Bio:
Prof. Nae-Lih Wu is currently a Distinguished Professor in the Department of Chemical Engineering at National Taiwan University (NTU). He received Ph.D. in Chemical Engineering from Pennsylvania State University in 1987. His research interests include:
1. synthesis and characterization of electrode and component materials for
electrochemical devices, including supercapacitors and Li-ion batteries;
2. development of advanced in-situ/in-operando analytic methodologies based on
synchrotron facilities in charactering these materials and devices;
3. nano-materials synthesis and applications.
Prof. Wu once served as a Consultant to the Ministry of Economic Affairs in Taiwan, Director of the Energy Research Center, Chairman of the Chemical Engineering Department at NTU, and an editorial board member of Journal of Power Sources. He has over 130 refereed papers, 9 Taiwan patents, and 4 U.S. patents. He is currently serving as an Associate Editor for Electrochemical Society Journals.