Understanding Transformations in Battery Materials Using in Situ and Operando Experiments: Progress and Outlook

Over the past decade, significant progress has been made toward understanding the intricate dynamics that underlie the operation of batteries. The development of in situ and operando experimental techniques has been critical for revealing how materials change, transform, and degrade within battery systems during charge and discharge. This Perspective first highlights recent successes in the use of in situ and operando experiments to understand dynamics in a variety of different battery materials, including alloy/conversion electrodes, intercalation electrodes, and alkali metal anodes. We then discuss four emerging focus areas in which in situ and operando experiments are expected to make an impact. These areas include solid-state batteries, improved data analytics, the linkage of dynamics across time and length scales, and understanding the atomic-scale evolution of interphases. We expect that continued progress in investigating the elaborate inner workings of battery systems across time and length scales will help to advance future battery technologies.