Roles of Polymerized Anionic Clusters Stimulating for Hydrolysis Deterioration in Li₇P₃S₁₁

The atmospheric hydrolysis reaction in sulfide solid electrolytes (SEs) is destructive to their Li-ion conducting behavior, but a comprehensive understanding of their reaction steps is still lacking. Therefore, here, we studied the atmospheric deterioration of a well-known sulfide SE, Li₇P₃S₁₁, based on the analogies between the hydrolysis and electrochemical reactions. Through analyzing the change in the S₂pbinding energy, we found that the anionic structures of both air-exposed and delithiated sulfides were altered owing to Li-ion loss. Considering the high diffusivity and massive hydrate formation ability of Li ions, we found that the anionic structures of both air-exposed and delithiated sulfides were altered. We showed that the hydrolysis of sulfide SEs with anionic polymerization has a thermodynamically favorable final state energy of −3.85 eV because S ions offer high degrees of freedom in their charge states ranging from −0.89 to −0.31e.