Interface Issues of Inorganic Solid‐State Electrolytes in Secondary Magnesium Batteries

ABSTRACT Solid‐state magnesium batteries (SSMBs) have gained significant attention as promising candidates for next‐generation safe energy storage systems because of the abundance of magnesium (Mg) in the earth's crust, superior energy density, and inherent nonflammability. However, the development of inorganic solid‐state electrolytes (ISSEs), which are critical for SSMBs, is hindered by two major challenges: the limited diffusivity of Mg 2+ and inefficient interfacial charge transfer kinetics between the electrodes and electrolytes. Recent advancements in material design and interfacial engineering have addressed these challenges with remarkable progress. Therefore, this review systematically discusses the mechanisms for optimizing the performance of ISSEs, focusing on ion transport kinetics, mechanical strength, and electrochemical stability. A crystal‐structure‐based classification framework is employed to critically analyze three major ISSE categories, including boride, oxide, and chalcogenide electrolytes. In addition, current engineering strategies for interfacial optimization in magnesium batteries are summarized. Finally, this review also highlights current challenges and possible directions for improving interfacial contacts in future practical applications. This comprehensive analysis aims to provide theoretical guidance for the development of high‐energy‐density SSMBs.