Li$_2$BMQ$_4$（B = Ca、Sr 和 Ba；M = Si、Ge 和 Sn；Q = O、S 和 Se）体系中一类空气稳定的硫族化物固态电解质
A family of air-stable chalcogenide solid electrolytes in Li$_2$BMQ$_4$ (B = Ca, Sr and Ba; M = Si, Ge and Sn; Q = O, S and Se) systems
AI总结：
本文通过高通量计算与实验结合，在 Li$_2$BMQ$_4$ 体系中发现了空气稳定、低活化能的快锂离子硫族化物固态电解质，并通过 Cl$^-$ 掺杂将室温电导率提升约三个数量级，为锂离子电池固态电解质设计提供了新方向。
摘要：
结合高通量第一性原理计算与实验测量，我们在 Li$_2$BMQ$_4$（2114，B = Ca、Sr 和 Ba；M = Si、Ge 和 Sn；Q = O、S 和 Se）体系中识别出一类新型快锂离子硫族化物导体。我们的计算表明，该新体系中大多数热力学和动力学稳定的硫化物和硒化物表现出超低的 Li$^+$ 离子迁移活化能（0.16 eV ~ 0.56 eV）以及约 2 eV 至 3.5 eV 之间的可观带隙。我们成功合成了 Li$_2$BaSnS$_4$ 和 Li$_2$SrSiS$_4$，并通过 H$_2$S 气体测量证明它们具有优异的耐湿稳定性。电化学阻抗测量表明，2114 体系表现出固态离子导体的典型特征，其室温 Li$^+$ 电导率接近 5$\ imes$10$^{-4}$ mS/cm，与我们的分子动力学模拟结果一致。此外，我们还从理论上研究了在 S$^{2-}$ 位点取代 Cl$^-$ 的情况。与未掺杂化合物相比，掺杂化合物的电导率显著提高，增幅约为三个数量级（最高可达 0.72 mS/cm）。这些发现为进一步探索具有稳健空气稳定性和增强离子电导率的潜在硫族化物固态电解质材料提供了有价值的见解，可用于锂离子电池的实际应用。
英文摘要：
Combining high-throughput first-principles calculations and experimental measurements, we have identified a novel family of fast lithium-ion chalcogenide conductors in Li$_2$BMQ$_4$ (2114, B = Ca, Sr and Ba; M = Si, Ge and Sn; Q = O, S and Se) systems. Our calculations demonstrate that most of the thermodynamically and kinetically stable sulfides and selenides in this new system exhibit ultralow Li$^+$ ion migration activation energy (0.16 eV ~ 0.56 eV) and considerable bandgaps varying between ~ 2 eV and 3.5 eV. We have successfully synthesized Li$_2$BaSnS$_4$ and Li$_2$SrSiS$_4$, and they exhibit excellent moisture stability through H$_2$S gas measurements. Electrochemical impedance measurements indicate 2114 systems show the typical features of solid ionic conductors, with a room-temperature Li$^+$ conductivity close to 5$\times$10$^{-4}$ mS/cm aligning with our molecular dynamics simulations. Furthermore, we have theoretically investigated the substitution of Cl$^-$ at S$^{2-}$ site. The doped compounds display significantly higher conductivity, with an increase of about three orders of magnitude (up to a maximum of 0.72 mS/cm) compared to the undoped compounds. These findings offer valuable insights for the further exploration of potential chalcogenide solid electrolyte materials with robust air stability and enhanced ionic conductivity for practical applications in lithium-ion batteries.
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