Double regulatory effect of As-designed Na3Sb1-xAsxS4 sodium superionic conductors

All-solid-state sodium-ion batteries (NIBs) are emerging as a strong contender to the widely used lithium-ion batteries due to their abundant resources and high safety performance. Solid-state electrolytes, as the key component of SSBs, have gained widespread attention for their high safety and chemical stability. This study presented a novel solid glass-ceramic electrolyte, Na3Sb0.75As0.25S4, which was synthesized by high ball milling and heat treatment. The findings demonstrate that elemental As can have a dual effect of improving ionic conductivity and successfully lowering H2S gas emission. Na3Sb0.75As0.25S4 exhibits superior performance in the cubic phase due to the partial replacement of Sb by As, with ionic conductivity up to 2.42 mS/cm and a low activation energy of 0.119 eV at room temperature. Furthermore, it releases only 0.017 cm3/g H2S in a conventional humidity environment for 30 min, much lower than the amount of 0.05 cm3/g H2S released by undoped Na3SbS4, making it an excellent candidate for all-solid-state NIB electrolyte.