Engineering Triple-Phase Interfaces with Hierarchical Carbon Nanocages for High-Areal-Capacity All-Solid-State Li-S Batteries

All-solid-state lithium-sulfur batteries (ASSLSBs) have garnered widespread attention due to their advantages of high energy density and enhanced safety. However, the typical composite structure composed of solid-state electrolyte (SE), discrete conducting carbon black, and microsized sulfur (μ-S) with long-range Li⁺/e⁻ conducting path and huge volume changes, suffers from sluggish charge transport and severe electrochemical-mechanical failure. In this work, a unique hierarchical carbon nanocage (hCNC) is applied as a continuous conducting network where nanosized sulfur are confined. Due to the synergistic effects of multi-dimensional (particle, interface, and electrode) structural engineering, this new sulfur-carbon composite cathode (S@hCNC39) can achieve uniform distribution of sulfur and carbon, and efficiently constructs triple-phase interfaces, showing enhanced charge-carrier transport and improved electrochemical-mechanical stability. Remarkable cycling performance of 89% after 300 cycles at 0.2 C at 30 °C is realized in ASSLSBs assembled with S@hCNC39. Notably, ASSLSBs achieve an ultrahigh areal capacity of 9.95 mAh cm⁻² with stable cycling at 60 °C with high sulfur contents of 40% and high sulfur loadings of 6 mg cm⁻². These results provide critical insights into the design of rational sulfur-carbon composites and offer a viable approach to enhance the overall performance of ASSLSBs.