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 Li2S, and by severe cathode-related volumetric changes during cycling. Here, we prepare a Li2S-based cathode composite with high mixed-conductivity and stability, by infiltrating a Li2S–LiI active material solution into a mesoporous carbon replica with ~10-nm-sized pores, followed by mixing with a liquid-phase-synthesized Li6PS5Br 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.