Exposed (111) Plane Engineered of Lead‐Free Perovskite Cs2SnCl6 Octahedra for DMC Sensing in LIB Electrolyte Leakage Detection

Abstract Dimethyl carbonate (DMC), as a major component of electrolytes, can be used as a marker for monitoring electrolyte leakage in lithium‐ion batteries (LIBs). Herein, lead‐free perovskite Cs 2 SnCl 6 octahedra with (111) plane as the exposed surface are synthesized by a simple antisolvent method and the gas sensor based on these octahedra shows excellent adsorption performance for DMC molecules. The response value for 100 ppm DMC is 7.05 and response/recovery time is 82 s/83 s, as well as almost no degradation in performance during a one‐month stability test. DFT calculations of the density of states and band structure reveal the adsorption of DMC molecules on perovskite surface. And it is first proposed that the adsorption conformations of DMC molecules have a significant influence on the adsorption energy. In situ infrared absorption spectrometry demonstrates the adsorption and decomposition process of DMC molecules. This mechanism provides crucial insights for the essence of lead‐free perovskite gas sensing, while offering the guidance for designing high‐performance lead‐free perovskite gas sensing materials.