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

Abstract

Here, we report the SiS2–NaBr double-doped sulfide superionic conductor Na3.02Si0.1Sb0.9S3.92Br0.08. The dual-doping effect of SiS2 and NaBr in the Na3SbS4 electrolyte was investigated by mechanical ball milling and high-temperature heat treatment. The improved glass–ceramic Na3.02Si0.1Sb0.9S3.92Br0.08 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 Na3SbS4) at room temperature. Moreover, the electrochemical property test was characterized by a higher critical current density of 1.228 mA/cm2 (0.585 mA/cm2 for Na3SbS4) and stable cycling at 0.1 mA cm−2 current densities exceeding 120 h (50.33 h for Na3SbS4). Some Si atoms occupying the Sb position greatly contributed to the formation of the Na3SbS4 high-ionic conductive phase. The introduction of an appropriate amount of halogen improved the compactness of the sample and nearly suppressed the majority of H2S release from the original electrolyte. The substitution effect and the ion conduction structure were analyzed in detail.