Cascade H2O/H2S Scavenging Strategy for Moisture-Stable Argyrodite-Type All-Solid-State Batteries

The argyrodite-type Li6PS5Cl (LPSCl) is a promising solid electrolyte for all-solid-state batteries (ASSBs), but its vulnerability toward moisture causes structural degradation and H2S evolution. To address these challenges, a dual H2O/H2S 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 H2O 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 H2S mitigates the release of H2S gas by forming CaS, demonstrating that CaO ensures the stable operation of ASSBs. Benefiting from this cascade H2O/H2S 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 H2O/H2S scavenger.