Multi‐modal Operando Analysis of Lithium–Sulfur Batteries: A Comparative Study on the Influence of Electrolyte Composition

ABSTRACT The effect of electrolytes on battery cell performance is multifaceted, and it is difficult to isolate their impact on individual processes. Operando analysis of batteries is a powerful tool to investigate battery degradation mechanisms. By combining different techniques on the same cell a wider perspective can be opened and enables easier cross‐correlation. Here, we introduce a fully laboratory‐based multimodal operando platform that synchronizes EIS/DRT, Raman spectroscopy, UV–vis reflectance spectroscopy, temperature monitoring, and galvanostatic cycling in one sealed Li–S cell. The platform is demonstrated over an extended observation window of up to 20 cycles to compare electrolyte‐dependent polysulfide speciation, transport limitations, and resistance evolution. The experimental design is optimized for reproducible mechanistic characterization and is not intended as a benchmark of practical cell performance or long‐term cycle life.