Cascade H ₂ O/H ₂ S Scavenging Strategy for Moisture-Stable Argyrodite-Type All-Solid-State Batteries

The argyrodite-type Li 6 PS 5 Cl (LPSCl) is a promising solid electrolyte for all-solid-state batteries (ASSBs), but its vulnerability toward moisture causes structural degradation and H 2 S evolution. To address these challenges, a dual H 2 O/H 2 S scavenging additive, CaO, is proposed to stabilize LPSCl under humid conditions, thereby enabling the reliable operation of ASSBs. Owing to its strong hygroscopicity, CaO preferentially reacts with H 2 O to produce Ca(OH) 2, suppressing the initiation of LPSCl hydrolysis. Subsequently, the spontaneous reaction between the resulting Ca(OH) 2 and the inevitably evolved H 2 S mitigates the release of H 2 S gas by forming CaS, demonstrating that CaO ensures the stable operation of ASSBs. Benefiting from this cascade H 2 O/H 2 S scavenging behavior, the ASSBs employing CaO-incorporated LPSCl achieve stable electrochemical performance for 350 cycles after 1 h exposure in RH 50%, while those employing moisture-exposed LPSCl underwent early failure around 100 cycles, highlighting the efficacy of the dual H 2 O/H 2 S scavenger.