Na3SbSe4-xS x as Sodium Superionic Conductors.

Na based all-solid-state batteries are a promising technology for large-scale energy storage applications owing to good safety properties and low cost. High performance solid electrolyte materials with high room temperature ionic conductivity, good electrochemical stability and facile synthesis are highly desired for the commercialization of this technology. In this work, we report the synthesis and characterization of a novel fast Na-ion conductor, cubic Na3SbSe4, with an excellent ionic conductivity of 0.85 mS cm-1 at room temperature, and a group of S doped variants. Na3SbSe4 exhibits good compatibility with metallic Na and good stability in a wide voltage range. The application of this compound as solid electrolyte is demonstrated in all-solid-state Na-ion cells cycled at room temperature.