Zn doping for enhanced sodium-ion conductivity and air stability in Na3SbS4 solid electrolyte

Solid electrolytes equipped battery show promise in solving energy storage and ecological concerns owing to their excellent electrical conductivity and chemical stability. Only a limited number of substances satisfy the demanding criterion of high ionic conductivity (≥ 10 −3 S/cm), while using non-toxic elements. In this work, the designed Na 3.3 Zn 0.1 Sb 0.9 S 4 electrolyte, a zinc-doped sodium sulfide ion conductor, with a maximum conductivity of 1.48 × 10 −3 S/cm under normal conditions, and a low activation energy of 0.128 eV was achieved. This was ruled by substituting low-valence Zinc for antimony in the SbS 4 3− cell, maintaining efficient ion transport pathways. Additionally, the electrolyte demonstrated strong air stability under humid conditions and emitted minimal H 2 S. The origin of heterovalent ion doping and the impact of thermal effects on electrochemical performance were discussed in detail, which were crucial to promote the development of sodium-ion solid electrolytes.