Linking Structure to Function at Electrochemical Interfaces—Li-Ion and Beyond

Despite the fact that the solid electrolyte interphase (SEI) on Li metal was described 45 years ago, it is still the only aspect of the battery that has ambiguity in function. As a community, we have struggled to establish structure-property-performance relationships for the SEI because it is a nanoscale composite that contains chemical compounds whose properties deviate from their bulk counterparts. In this talk, I will describe how we have used nuclear magnetic resonance (NMR) spectroscopy to characterize the structure and dynamics of interfacial phenomena in Li-ion and beyond Li-ion batteries and correlate these features with battery performance. In particular, I will focus on the use of NMR to quantify the source of Li inventory loss, the mechanism of transition metal dissolution, structural evolution at the electrode/electrolyte interface, and the function of the SEI. Insight from these methods allow us to determine the precise mechanisms of failure that arise inside of functional devices as well as develop new approaches to mitigate performance decline.