CPOS Seminar: "Membranes and Megawatts: Revealing Mechanisms with NMR Spectroscopy"

Speaker: Leo W. Gordon, Postdoctoral Researcher, Clément Group, Materials Department and Materials Research Laboratory, University of California Santa Barbara

Aluminum holds great promise as an alternative to lithium for batteries, due to its high natural abundance, low cost, and non-flammability. To match these characteristics, we pair aluminum anodes with sustainable, organic-based electrode materials. These organic electrodes are promising but have thus far received little attention, resulting in a poor understanding of how they can store charge in aluminum batteries. Here, we apply nuclear magnetic resonance (NMR) spectroscopic methods to analyze these materials, investigating the electrochemical reaction products and electrolyte speciations to determine the electronic and ionic charge storage mechanisms for the class of anthraquinone-based electrodes.

Separately, we use NMR methods with spatial resolution to probe transport mechanisms of ions into membranes. There has been recent dispute over the origin of the chemical potential gradient across certain types of membranes, with some believing it is a result of a pressure gradient, while others propose a concentration gradient as the driver. In this study, we monitor the transport of lithium ions from bulk solution into crosslinked poly(ethylene glycol diacrylate) membranes and compare to theoretical models. This NMR technique enables understanding of partitioning behaviors of solutes and solvents, while also capturing critical transport properties.

These two case studies present very different ways to obtain mechanistic understanding of functional organic materials, and both approaches inform rational design of next-generation battery and separations technologies.