Probing the interfacial chemistry of solid-state lithium batteries

This review aims to give a brief overview of the current state-of-the-art in the analysis of the interfacial chemistry in solid-state batteries. Despite generally regarded as being decisive for the ultimate success of these energy storage devices, this surface chemistry has so far only been explored to a rather limited extent in the scientific literature, but constitutes a research area which is currently undergoing rapid progress due to the growing interest in solid-state electrolyte materials and their corresponding battery applications. The review discusses the technical difficulties in performing these interfacial analyses for both ceramic and solid polymer electrolyte systems, and describes ways to overcome them using different methodologies: electrochemical techniques (primarily impedance spectroscopy), photoelectron spectroscopy, microscopy, and other less familiar experimental techniques. Modelling studies of the solid electrolyte-electrode interface are also included. It is concluded that especially the interfacial chemistry of polymer electrolytes has indeed been an understudied area. Furthermore, the review shows that analytical techniques employed so far have been largely complimentary to each other, but that joint studies and the development of novel analytical tools exploiting large-scale facilities will boost this research over the coming years.