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

Abstract

All-solid-state lithium–sulfur batteries (ASSLSBs) exhibit high energy densities, operate safely, and suppress polysulfide shuttling. However, their electrochemical performance is restricted by the insulating nature of S and Li₂S and the severe cathode-related volumetric change during cycling. Herein, we report a Li₂S-based cathode composite (AM/CR10/SE-liq/VGCF, or ACSV) with high mixed-conductivity and stability, fabricated by infiltrating a Li₂S–LiI active material (AM) solution to a mesoporous carbon replica with ~ 10-nm-sized pores (CR10), followed by mixing the AM–CR10 composite with a liquid-phase-synthesized Li₆PS₅Br solid electrolyte (SE-liq) and vapour-grown carbon fibres (VGCFs). Benefiting from its mechanically reinforced, three-dimensional ion/electron-conducting structure, the ACSV-based ASSLSB cathode exhibits high discharge capacity (1009 mAh g^− 1, 20 cycles, 298 K, 0.05C; 86.6% of the theoretical capacity of Li₂S) and high reversible capacity (650 mAh g^− 1, 100 cycles, 298 K, 0.1C). The findings underscore the feasibility of developing high-performance ASSLSBs by designing three-dimensional mixed-conducting mechanically robust cathodes.