Evidencing Phase Transformations of LiPSCl Argyrodite under Ambient Air and Dry Room Exposure.

All-solid-state electrolytes have been extensively studied for the last years in order to achieve high conductivities and improved safety among lithium-ion technologies. Sulfide electrolytes, such as argyrodites (LiPSX, X = Cl, Br, and I), succeed to show high performances despite their poor chemical stability. As a matter of fact, argyrodite reactivity to water is known as a common drawback for easy implementation and requires the use of dry room for cell preparation. The understanding of argyrodite degradation under ambient air exposure is a key for the development of stable electrolytes, coatings, and processes and has been incompletely explored until now. This study brings unreported elements of comprehension around the degradation mechanisms of LiPSCl solid electrolyte using transmission electron microscopy (TEM) and complementary spectroscopic techniques.