Economical sodium source prepared Na3SbS4 electrolyte with improved electrochemical performance by La doping

Solid electrolytes are expected to improve the next-generation rechargeable batteries in terms of safety and cost issues. In the present study, we designed a conventional sulfide sodium-ion conductor Na3+2xLaxSb1-xS4 synthesized from Na2S·9H2O as raw material. For optimized electrochemical behavior, the partial substitution of Sb with La in Na3SbS4 was modified by broadening Na+ ion channels and increasing interstitial Na+ ions in the network lattice. The structural characterization verified the increase in crystallinity after subsequent heating at 450 °C. The composition and structural design realized a high room temperature conductivity of 0.52 mS cm−1 and low activation energy of 0.069 eV for the Na3.1La0.05Sb0.95S4 sample. Moreover, this sulfide electrolyte was equipped with additional advantages, such as much lower electronic conductivity than Na3SbS4 and air stability against the humid atmosphere.