Silicon‐Based Anodes for Sulfide Solid‐State Batteries: Failure Mechanisms and Multiscale Design Strategies

ABSTRACT Research on silicon (Si)‐based solid‐state batteries (SSBs) has grown rapidly in recent years, drawing considerable attention from the scientific community. Especially, Si‐anodes paired with sulfide solid electrolytes are at the forefront of high‐energy density, offering pathways to enhanced safety and cycle life. Unfortunately, silicon anodes suffer from intrinsically coupled electrochemical degradation and mechanical failure, interfacial instability, and structural pulverization driven by massive volumetric expansion. In this review, we comprehensively examine recent advances in Si‐based anode and propose strategies via material‐, electrode‐, and cell‐level engineering to overcome these obstacles. Furthermore, we also briefly discuss sulfide solid‐electrolyte types, intrinsic limitations, strategies to improve their ionic conductivity, and scalable methods for mass production and low cost. This review also explores cathode pairing, intrinsic material, and interfacial limitations with sulfide electrolytes, and highlights the development of high‐voltage, high‐mass‐loading cathodes compatible with Si anodes. Finally, in situ and operando characterization techniques are highlighted for their critical role in elucidating failure mechanisms and guiding rational electrode and interface design. The highlighted research priorities serve as a roadmap, offering insights to support continued exploration and advancement in this dynamic area.