Silicon Composite Anode Degradation during Freeze-Thaw Temperature-Swings.

Batteries used in space applications can be exposed to large temperature-swings. During these large temperature-swings, the battery electrolyte can undergo a phase transformation from a liquid to a solid and back to a liquid. The nature of the solvent and the type of salt influence the crystallization processes. Herein, we aim to understand how pressure build-up in confined regions of an electrode (e.g., pores) influences degradation processes in silicon-oxide graphite anodes undergoing freeze-thaw dynamics. Our results show that high porosity electrodes lead to a greater density of nucleation sites for electrolyte crystallization. Local pressure build-up at pores results in active material loss and decreased cycle lifetime in batteries exposed to extreme temperature swings.