Moisture-Stable Chalcogenide Solid Electrolytes in Li₂BMQ₄ (B = Ca, Sr, and Ba; M = Si, Ge, and Sn; Q = O, S, and Se) Systems

Identifying new solid-state electrolytes is key for advancing all-solid-state batteries. Combining high-throughput calculations and experiments, we have identified a family of moisture-stable chalcogenide ionic conductors in Li2BMQ4 (2114, B = Ca, Sr, and Ba; M = Si, Ge, and Sn; Q = O, S, and Se) systems. The calculations demonstrate the 2114 systems have low Li+ migration energies (0.16–0.56 eV) and considerable bandgaps (about 2–3.5 eV). The experimentally synthesized Li2BaSnS4 and Li2SrSiS4 show typical features of solid ionic conductors, with a room-temperature Li+ conductivity close to 5 × 10–4 mS/cm. Furthermore, for Cl-doped compounds, the calculated ionic conductivity is enhanced by approximately 3 orders of magnitude, reaching a maximum of 0.72 mS/cm, despite synthesis hurdles from impurities. These findings offer valuable insights for the further exploration of potential chalcogenide solid electrolyte materials with robust moisture stability and enhanced ionic conductivity for practical applications in lithium-ion batteries.