Air-stable iodized-oxychloride argyrodite sulfide and anionic swap on the practical potential window for all-solid-state lithium-metal batteries

Among inorganic solid-state electrolytes, argyrodite sulfides are capable candidates for their superb-ionic con-ductivity, versatility over synthesis, and cost. However, the growth of resistive interphase, limited oxidative stability, and highly-oxophilic nature are limiting factors. Herein, we report iodized-oxychloride argyrodite with robust SEI containing in-situ formed LiI and Li2O upon treating the sulfide via fumy iodine. Sacrificial iodine -induced dendrite suppression capability up to 21 mA cm-2 was achieved. Ultrahigh-lithium compatibility with a high cutoff-capacity of 10 mAh cm-2 was cycled at 10 mA cm-2 for 260 hr. Moreover, durable cycling was performed at 0.1 mA cm-2 for 11,000 h, 2 mA cm-2 for 1000 h, and 6 mA cm-2 for 460 h. Stepwise CV mea-surement demonstrates enhanced "True practical potential window" stability up to 3.42 V vs. Li/Li+. Cell per-formance of Li6PS4.8O0.2Cl-5 wt. % I2 with Li-In at 1 C and 3 C has achieved capacity retention of 89.6 % and 89.9 % after 200 and 300 cycles. Outstanding cyclability with Li-metal at 0.4 C with an initial-discharge capacity of 137.27 mAh g-1 was achieved. Enhanced tolerance to moisture with suppressed H2S gas generation was proven by coupling in-situ Raman measurements.