Advanced Raman spectroscopy for battery applications: Materials characterization and operando measurements

Raman spectroscopy is a powerful and versatile tool for battery research, elucidating the structural and bonding states of key components such as electrodes and electrolytes. This review highlights recent advancements in Raman spectroscopic techniques for both static material characterization and operando analysis of electrochemical reactions. Regarding static characterization, studies on the solvation structure of organic liquid electrolytes and the crystallographic analysis of electrode active materials are discussed. In addition, Raman-based image analysis is considered for visualizing the spatial distribution of structural components within composite electrodes. In Sec. III, we provide a comprehensive overview of ionic transport phenomena inferred from concentration variations, electrode degradation processes occurring during cycling, and the fundamental electrochemical reactions involved in electrode processes. Furthermore, a multi-scale analytical approach for all-solid-state sodium batteries has been introduced, enabling a comprehensive understanding of electrochemical processes from the atomic level to the μm scale. These advancements in Raman spectroscopy provide valuable insights into battery chemistry and significantly contribute to the development of next-generation energy storage systems.