Abstract: Earth abundant, low cost, and safe energy storage systems are critical for using renewable energy sources and driving energy efficiency on a global scale. However, technological development of emerging energy storage systems has been hindered, in part, by limited molecular-level understanding of how they function and fail. Here, I will discuss recent progress in our group in the molecular-scale understanding and design of two different energy storage systems: rechargeable aluminum batteries for earth abundant, safe electrochemical energy storage and phase-change material (PCM) nano-emulsions for flowable thermal energy storage. In rechargeable aluminum batteries, we couple electrochemical experiments with solid-state nuclear magnetic resonance (NMR) measurements to elucidate new understanding of their ionic and electronic charge storage mechanisms. For example, in Chevrel phase electrodes, reversible aluminum-ion intercalation is shown to occur simultaneously with electrochemical anionic redox, an unusual electronic charge storage mechanism that differs fundamentally from that observed in lithium-ion intercalation electrodes. In PCM nano-emulsions, we study how thermal cycling and shear affect phase and flow instabilities by using liquid-state NMR spectroscopy, rheo-NMR, and magnetic resonance imaging (MRI) velocimetry methods. For example, in a model PCM nano-emulsion composed of octadecane, stearic acid, and water, we quantify supercooling effects, reveal unexpected surfactant behavior upon melting, and elucidate shear-induced mass transport that results in non-uniform flow fields. Overall, the results suggest molecular-level design principles aimed at developing rechargeable aluminum batteries and PCM nano-emulsions for diverse energy storage applications.

Bio: Robert J. Messinger is an Associate Professor and the Director of Graduate Studies in the Department of Chemical Engineering at The City College of New York (CCNY). He earned a B.S. in chemical engineering from The Ohio State University (2006) and a Ph.D. in chemical engineering from the University of California, Santa Barbara (2012). Afterwards, he studied physical chemistry and electrochemistry at the CNRS, France, first as a European Union Marie Curie Postdoctoral Fellow in Orléans (2012-2014) and then jointly with the CNRS and Grenoble Institute of Technology (2014-2015). At CCNY, his research group studies electrochemical materials, chemical processes, and multi-phase fluids up from the molecular level for energy storage and recycling. He is an expert in nuclear magnetic resonance (NMR) spectroscopy. Prof. Messinger won an NSF CAREER award (2019) and is the Founding Director of the NASA-CCNY Center for Advanced Batteries for Space.