(72d) Peering into Batteries: Insights into Electrochemical Behavior through Operando and in-Situ Characterization

Emerging new applications demand expanded function of batteries. Electric vehicle batteries demand high energy density, long calendar, high cycle life, and increasingly fast charge. Large scale batteries to enable intermittent renewable energy such as wind and solar must be low cost and long life with less emphasis on energy density. In order to meet these ever-changing application demands new battery systems must be pursued. However, the full understanding of battery electrochemical behavior is challenged by the inherent complexity of the phase transitions of electroactive materials, the evolution of electrode electrolyte interfacial reactions, and their function far from equilibrium. To date, most interrogation approaches of batteries have been static, and thus are unable to track changes arising from dynamic battery (dis)charge behavior. Observing materials over multiple length or spatial scales is needed to provide information over a series of size domains including atomic, crystallite/particle, electrode, and battery system. The time dimension should be considered over many orders of magnitude ranging from sub-second electrochemical processes to years of functional lifetime. By coupling time and spatial resolution, in situ and operando characterization over multiple size and time domains become powerful approaches to probe spatially inhomogeneous transitions within materials or electrodes, causes of sluggish ion transport, and possible interfacial reactions. This presentation discusses the application of in-situ and operando methods over various length scales to gain insight into dynamic electrochemical processes.