Double-substituted Na3SbS4 Glass–Ceramic electrolyte with excellent performance for sodium-ion batteries

Here, we report the SiS 2 –NaBr double-doped sulfide superionic conductor Na 3.02 Si 0.1 Sb 0.9 S 3.92 Br 0.08 . The dual-doping effect of SiS 2 and NaBr in the Na 3 SbS 4 electrolyte was investigated by mechanical ball milling and high-temperature heat treatment. The improved glass–ceramic Na 3.02 Si 0.1 Sb 0.9 S 3.92 Br 0.08 solid electrolyte obtained a high ionic conductivity of 2.26 × 10 −3  S/cm and a low activation energy of 0.077 eV (0.25 eV for Na 3 SbS 4 ) at room temperature. Moreover, the electrochemical property test was characterized by a higher critical current density of 1.228 mA/cm 2 (0.585 mA/cm 2 for Na 3 SbS 4 ) and stable cycling at 0.1 mA cm −2 current densities exceeding 120 h (50.33 h for Na 3 SbS 4 ). Some Si atoms occupying the Sb position greatly contributed to the formation of the Na 3 SbS 4 high-ionic conductive phase. The introduction of an appropriate amount of halogen improved the compactness of the sample and nearly suppressed the majority of H 2 S release from the original electrolyte. The substitution effect and the ion conduction structure were analyzed in detail.