The value of in situ/operando Raman spectroscopy in all-solid-state Li batteries

All-solid-state Li batteries (ASSLBs) are promising owing to their high safety and energy density. A comprehensive understanding of the failure mechanisms of ASSLBs can facilitate the development of strategies to improve their performance. Various real-time characterization techniques can be used to understand such mechanisms. Among such techniques, in situ/operando Raman spectroscopy (IS/O-RS) is commonly used because it can detect the molecular structural and compositional evolution of most of the electrodes, solid electrolytes (SEs), and their interface in ASSLBs. Herein, we review the applications of IS/O-RS in research on ASSLBs. We first introduce the principles, classifications, and development of IS/O-RS. We then describe various studies that used IS/O-RS to explore electrode-electrolyte interfaces, electrodes, and SEs. Finally, we summarize the review findings and propose optimized applications of IS/O-RS in research on ASSLBs. We hope that this review can enable researchers to use IS/O-RS to directly and conveniently investigate ASSLBs and then use their findings to improve the performance of ASSLBs.