High-areal-capacity all-solid-state Li-S battery enabled by dry process technology

Abstract

All-solid-state lithium-sulfur batteries (ASSLSBs) based on sulfide solid electrolyte (SSE) hold great promise as the next-generation energy storage technology with great potential for high energy density and improved safety. However, the development of practical ASSLSBs is restricted by the scalable fabrication of sulfur cathode sheets with outstanding electrochemical performance, which remains a complex and challenging endeavor. Herein, we employ dry electrode technology to fabricate free-standing sulfur cathode sheets with both high sulfur content and loading. By utilizing polytetrafluoroethylene (PTFE) binders with unique fibrous morphologies in the dry electrodes, we achieved sulfur cathode sheets with high flexibility without compromising ionic and electronic conductivity. Remarkably, even with thickened dry cathode sheets featuring high sulfur loading of 4.5 mg cm^-2, the sulfur cathodes exhibit high initial discharge capacity of 1114.8 mAh g^-1 with good cycle stability and rate capability. Additionally, we successfully demonstrate the construction of sheet-type all-solid-state Li_3.75Si/SSE/S cells, showcasing favorable electrochemical performance with a high reversible capacity of 1067.4 mAh g^-1 after 30 cycles even at a high sulfur loading of 4.5 mg cm^-2 and high current density of 1 mA cm^-2 (0.2C). Our findings represent a demonstration of batteries coupled with high-capacity sulfur cathode and lithiated silicon anode exhibiting exceptional electrochemical performance. It also underscores the significant potential of dry-process technology in addressing the critical challenges associated with the practical production of ASSLSBs. This contribution propels ongoing endeavors in the development of next-generation energy storage systems.