A unitized encapsulation architecture with durable epitaxial ion-conductive scaffolds for ultrastable solid-state sulfur cathode

Abstract

All-solid-state lithium–sulfur batteries (ASSLSBs) are emerging as next-generation energy storage systems, offering enhanced energy density, safety, and cost-effectiveness. However, the breakdown of the ion-conducting network within sulfur cathode limits their cycling life and poses challenges to practical application. Here, we design an innovative unitized encapsulation architecture to decouple and rebuild Li-ion transport pathways through interfacial spontaneous anion exchange behavior between Li_5.5PS_4.5Cl_1.5 and Li₃YBr₆ electrolytes. In this design, the internal Li_5.5PS_4.5Cl_1.5 enables durable intra-particle charge transfer trails, while the external halide Li₃YBr₆ framework establishes inter-particle Li-ion diffusion highways. This hierarchical ion-conducting mechanism facilitates efficient and durable Li-ion flow. Moreover, the core–shell configuration alleviates localized stress accumulation and catholyte irreversible decomposition during cycling, reinforcing robust ion-conducting pathways and persistent phase contact. The optimized sulfur cathode, S/LPSC@LYB-0.25, exhibits remarkable electrochemical performance, achieving 85% capacity retention over 1000 cycles under high sulfur loading of 8 mg cm⁻² and a high current density of 6.7 mA cm⁻². Developed pouch cells demonstrate unparalleled cycling stability under low stack pressure, retaining 76.9% capacity after 500 cycles. This work provides a practical and scalable strategy for tailored ion-conducing network architecture, advancing the industrial viability of ASSLSBs.