Effects of I and W co-doping on the structural and electrochemical characteristics of Na3SbS4 glass-ceramic electrolytes

Sodium-ion batteries are becoming a feasible choice for large-scale energy storage because of their low cost and vast selection of cathode materials. Here we report the design and synthesis of Na3SbS4–Na2W0.77S4I0.6 glass-ceramic electrolyte. A high room-temperature conductivity of 4.97 mS cm−1 was achieved by I doping. In this sulfide super-ionic conductor structure, I-substitution loosened the local bonding between Na and S (or I). The Sb in the SbS43− unit was replaced by W with a higher valence state, producing sodium vacancies while maintaining the 3D conduction pathways and resulting in fast ion transport. Additionally, the electrolyte Na3SbS4–Na2 W0.77S4I0.6 exhibited advantage of air stability against the humid atmosphere, which is a promising sulfide electrolyte for all solid-state sodium battery application.