Role of Electronic Conductivities Toward Practical All‐Solid‐State Lithium‐Metal/Sulfur Batteries

Abstract Inorganic solid‐state electrolytes (ISSEs) are recognized as promising candidates for safer and higher energy‐density all‐solid‐state lithium‐metal/sulfur batteries (ASSLM/SBs). Significant efforts have been directed at designing ISSEs with better chemical/electrochemical stability, superior lithium‐ion conductivity, and extensive working voltage windows. However, it has been investigated that Li‐dendrites produced within bulk ISSEs during the charge‐discharge process short‐circuit ASSLM/SBs. Notably, non‐negligble electronic conductivity (σ e ) ≈10 −8 S cm −1 can trigger nucleation of Li‐dendrites at intrinsic defects, e.g., grain boundaries, pores, and cracks of ISSEs, leading to a significant self‐discharge phenomenon in ASSLM/SBs. Furthermore, the reasons behind the insufficient utilization of cathode active materials (CAMs) in ASSLM/SBs at practical current densities or C‐rate remained overlooked. Herein, first, the strategies to reduce the σ e of sulfide‐based SSEs to prevent the Li‐dendrite formation at intrinsic defects are discussed. Second, strategies to enhance sulfur‐based cathodes' ionic and electronic conductivity (CAMs: Li 2 S and S 8 ) are addressed. How a balanced ionic and electronic conductivity in the positive cathode layer realizes fast kinetics and maximizes the utilization of CAMs and reversibility for high‐performance ASSLM/SBs is also discussed. Finally, an extensive conclusion and innovative perspectives are presented to give readers a clearer insight into ASSLM/SBs.