Impact of\nAmbient Air Contamination on the Performance\nof Argyrodite-Based All-Solid-State Lithium–Sulfur Batteries

Sulfide-based Li-argyrodites (Li<sub>5.5</sub>PS<sub>4.5</sub>Cl<sub>1.5</sub>) are considered as promising solid-state\nelectrolytes\nfor all-solid-state Li–S batteries (ASSLSBs) due to their high\nionic conductivity and suitable mechanical properties. However, their\nhygroscopic nature and intense decomposition behavior when combined\nwith conductive additives at the sulfur cathode introduce many variables\nthat can affect cell performance. This study demonstrates that an\noptimized amount of ambient air contamination during cycling can enhance\ncell performance. Multiple spectroscopic analyses reveal that the\nhydrolysis of Li<sub>5.5</sub>PS<sub>4.5</sub>Cl<sub>1.5</sub> can\nincorporate oxygen into the argyrodite structure, thereby increasing\nthe oxidative stability and generating additional redox active sulfur\nspecies. Methods, such as monitoring cell impedance growth, open-circuit\nvoltage changes, and <sup>31</sup>P NMR spectroscopic analysis, are\nproposed to determine the air-tightness of cell configurations. The\nresearch findings suggest that verifying the air-tightness of cell\nconfigurations is critical for ASSLSBs research to prevent misleading\nresults.