A composite cathode with a three-dimensional ion/electron-conducting structure for all-solid-state lithium–sulfur batteries

Abstract All-solid-state lithium–sulfur batteries exhibit high energy densities, operate safely, and suppress polysulfide shuttling. However, their electrochemical performance is restricted by the insulating nature of sulfur and Li 2 S, and by severe cathode-related volumetric changes during cycling. Here, we prepare a Li 2 S-based cathode composite with high mixed-conductivity and stability, by infiltrating a Li 2 S–LiI active material solution into a mesoporous carbon replica with ~10-nm-sized pores, followed by mixing with a liquid-phase-synthesized Li 6 PS 5 Br solid electrolyte and vapour-grown carbon fibres. Benefiting from a mechanically reinforced, three-dimensional ion/electron-conducting structure, the cathode exhibits high discharge capacity (1009 mAh g −1 , 20 cycles, 298 K, 0.05 C) and high reversible capacity (650 mAh g −1 , 100 cycles, 298 K, 0.1 C). These findings underscore the feasibility of developing high-performance all-solid-state lithium-sulfur batteries by designing three-dimensional mixed-conducting mechanically robust cathodes.