High-density silicon composite anodes exhibit significant volume changes during charging/discharging, leading to solid electrolyte interface (SEI) reformation. This study investigates the impact of SEI reformation and material evolution on cell performance using a correlated workflow incorporating X-ray microscopy, field-emission scanning electron microscopy tomography, elemental imaging, and deep learning-based microstructure quantification. The nanometer-sized SEI evolves into a micron-sized silicon electrolyte composite structure over prolonged cycles, causing active material underutilization and capacity loss. A chemomechanical model analyzes SEI/silicon reaction front stability, revealing how material properties influence capacity loss.

T. Vorauer, J. Schöggl, S. G. Sanadhya, M. Poluektov, W. D. Widanage, L. Figiel, S. Schädler, B. Tordoff, B. Fuchsbichler, S. Koller, R. Brunner