30: Using ultrafast lasers to investigate critical battery interfaces

Abstract: Batteries play a crucial role in our modern world: they are key in supporting renewable energy integration, strengthening grid stability, or enabling the electrification of transportation. This increasing demand for energy storage has led to complex battery systems, such as localized high concentration electrolytes (LHCEs). Due to the complex, inhomogeneous nature of LHCEs, understanding and engineering the formation of the double layer and the resulting solid electrolyte interphase (SEI) presents challenges. Sum-frequency generation (SFG) spectroscopy is an interface-selective nonlinear optical technique that provides molecular-level insight into buried interfaces, making it uniquely suited to probe the electrolyte structure and chemistry at the electrode surface without bulk signal interference. Here, we use vibrational SFG spectroscopy in operando to probe the double layer during the first cycle of a LHCE battery system and observe the formation of the SEI.