简介:

Rational Design of Cathodes for Rechargeable Lithium-Sulfur Batteries
Yongzhu Fu
Assistant Professor
Department of Mechanical Engineering
Indiana University – Purdue University Indianapolis

Abstract 
As the petroleum resources are being depleted and concern on the environmental pollution increases, electric vehicles (EVs) and renewable energies like solar and wind are becoming highly desirable. It is a big challenge to develop electrical energy storage systems that can meet the rigorous requirements on the weight and volume in EVs, and cycle life and efficiency for grid energy storage. Lithium-ion (Li-ion) batteries, representing the highest energy density battery chemistry, are believed to be one of the most promising systems for these applications. However, the capacities in the current cathode materials have reached their limits of <250 mAh/g. To further increase the energy density of Li-ion batteries, alternative high capacity cathode materials are being actively developed.
Sulfur, an abundant element on earth, is a promising cathode material with a high theoretical capacity of 1,672 mAh/g by taking two electrons per atom at ~2.1 V vs. Li/Li+. While the high capacity can significantly enhance the energy density of the batteries, the lower operating voltage can offer better safety. However, the commercialization of rechargeable lithium-sulfur (Li-S) batteries is impeded by two major challenges: (i) poor cycle life due to the dissolution of the polysulfide intermediates formed upon cycling and (ii) low electrochemical utilization of active materials in the cathode. This presentation will focus on a number of strategies that have been developed to overcome these problems, e.g., sulfur-conductive polymer nanocomposite, lithium-dissolved polysulfide cells, and lithium sulfide cathodes that exhibit unprecedented capacities and reversibility, holding the promise for practical applications.

About the Speaker 
Dr. Fu received his Ph.D. in Materials Science and Engineering from the University of Texas at Austin (UT-Austin) in 2007. The topic of his Ph.D. dissertation is “Development of New Membranes Based on Aromatic Polymers and Heterocycles for Fuel Cells”. After graduation, he worked at Lawrence Berkeley National Laboratory as a Chemist Postdoctoral Fellow for one and half years and developed a novel class of single-ion conducting materials for fuel cells and lithium-ion batteries. Then he joined Lynntech, Inc. as a Research Scientist and developed a variety of electrolyte and electrode materials for fuel cells, lithium-ion batteries, redox flow batteries, and supercapacitors. He has been PI on several projects (total $1.4 M) funded by federal agencies such as ONR and DOE. He returned to UT-Austin in 2011 and led the effort on the development of materials for rechargeable lithium-sulfur batteries. He acted as co-PI on a collaborative DOE ARPA-E project ($3 M) to develop hybrid Li-S batteries using solid-state electrolytes. In 2014, he joined the faculty at IUPUI as an Assistant Professor. He has published over 40 peer-reviewed journal papers in leading scientific journals, such as Angew. Chem., J. Am. Chem. Soc., Adv. Energy Mater., Nat. Commun., and Acc. Chem. Res. Dr. Fu holds 1 U.S. patent on proton-conducting membranes and 2 pending U.S. patents on lithium-sulfur batteries. His current research efforts focus on the development of new materials including ion-conducting electrolytes and ion-storage electrodes for electrochemical energy storage and conversion devices, and the study of materials’ structure-property-performance relationship through advanced material and electrochemical characterization.