High performance room temperature all -solid-state Na-Se x S battery with Na 3 SbS 4?coated cathode via aqueous solution

All-solid-state (ASS) Na–S batteries are promising for large-scale energy storage because of the incombustible solid electrolyte and avoiding the dissolution of intermediates. However, the poor contact between the active material and the solid electrolyte in the positive electrode leads to poor electrochemical performance. Here, we report an aqueous solution approach to fabricate Na3SbS4-coated SexS-based active materials for a Na–S battery working at room temperature. Compared with the Na3SbS4 and SexS mixed cathode, the coated cathode achieves significantly improved Na-ion diffusion kinetics and reduced impedance resistance. Additionally, the nanoparticle coating sustains the volume expansion of the cathode during cycling. The resulting batteries deliver an intensively enhanced specific capacity at various rates. Regardless of the mass loading, the Na3SbS4-coated cathode maintains a decent reversible capacity for the long-term discharge/charge cycling. The best battery achieves an initial discharge capacity of 509 mAh g−1 at a current density of 437.4 mA g−1 and capacity retention of 98.9% for 100 cycles. To the best of our knowledge, this is one of the best room temperature ASS Na–S battery so far. This work demonstrates that Na3SbS4 is very promising for the cathode coating purpose for ASS Na–S batteries. © 2020