Sulfide All-Solid-State Batteries: Interfacial Challenges and High-Energy Architecture Design

The development of all-solid-state batteries (ASSBs) has attracted significant interest owing to their potential to deliver high energy density, improved safety, and long cycle life. However, their practical implementation is still limited by the narrow electrochemical stability window of sulfide solid-state electrolytes, interfacial decomposition at high-voltage cathodes, and mechanically driven contact loss in composite electrodes. In this mini-review, we provide an overview of recent progress in sulfide-based solid-state electrolytes, with particular focus on interfacial degradation phenomena in composite cathodes and strategies to mitigate resistance growth through protective coatings and microstructural engineering. We also discuss the integration of high-energy-density anodes, including lithium metal, silicon-based, and anode-free designs, and examine how interlayers and stack-pressure management influence interfacial stability. Finally, we highlight the remaining challenges and outline future research directions for realizing durable, high-performance sulfide-based ASSBs.