Unveiling Ultra-High Ionic Conductivity in W‑Doped Na3SbS4: Grain Boundary Effects and Pure Bulk Transport

作者：Jana Königsreiter, B. Gadermaier, H. Wilkening · 发表于：Journal of the American Chemical Society · 年份：2025 · DOI：10.1021/jacs.5c05842 · 被引用次数：14 · 研究领域：Medicine

W-doped Na3SbS4 is a promising solid electrolyte for all-solid-state sodium batteries, exhibiting a sodium (Na+) ionic conductivity higher than 30 mS cm–1 (A. Hayashi, N. Masuzawa, S. Yubuchi, F. Tsuji, C. Hotehama, A. Sakuda, M. Tatsumisago, Nat. Commun. 2019, 10, 5266). This exceptional conductivity arises primarily from the introduction of sodium ion vacancies (V′Na) via supervalent substitution of Sb5+ with W6+. Using low-temperature impedance spectroscopy down to T = 113 K (−160 °C), we demonstrate that previously reported room temperature conductivities of Na2.9Sb0.9W0.1S4 are influenced by grain boundary resistances, which can only be effectively separated from the total conductivity at such low temperatures. Our results indicate that the pure Na+ bulk conductivity can reach 96 mS cm–1 (Dσ = 0.98 × 10–10 m2 s–1) at room temperature, as extrapolated from accurately measured low-temperature data (1.8 mS cm–1 at –130 °C). Our study suggests that further minimizing detrimental grain boundary effects enables extraordinarily fast long-range Na+ ion transport in this sulfide.