Moisture Robustness of Li₆PS₅Cl Argyrodite Sulfide Solid Electrolyte Improved by Nano-Level Treatment with Lewis Acid Additives

Sulfide solid-state electrolytes (SSSEs) are considered an auspicious alternative for all-solid-state batteries, because of their ductility and high ionic conductivity. One obstacle that thwarts SSSEs in large-scale applications is their lack of stability upon exposure to humid air. We used Lewis acid additives to treat the argyrodite Li6PS5Cl SSSE particles at the nanoscale level by dispersing them in solution mixtures, a method that had minimal impact on ionic conductivity. A series of investigations were conducted, involving the utilization of X-ray diffraction, in situ Raman spectroscopy, solid-state nuclear magnetic resonance, and X-ray absorption near-edge structure for characterizations. The SSSE demonstrated notable atmospheric stability by establishing a Lewis acid-base interaction with the additives. This interaction effectively shields the SSSE from moisture in humid air, ensuring that the bulk region remains structurally intact and undeteriorated. Therefore, treating SSSEs using Lewis acid additives is an auspicious approach to improving their moisture stability.