Researchers synthesized Al-substituted Na5FeS4 positive electrode materials for all-solid-state sodium batteries and found that slight aluminum substitution increased apparent sodium-ion transport while preserving high capacity. Na5Fe0.95Al0.05S4 delivered about 500 mAh g-1 in initial testing, maintained more than 460 mAh g-1 for over 70 cycles, and showed reversible sulfur-related structural changes during cycling.
