Recent progress of artificial SEI for high-energy lithium batteries: Mechanisms, fabrication strategies and structure-performance relationships

Lithium-ion batteries (LIBs) have attracted considerable attention owing to their excellent electrochemical properties. However, challenges such as dendrite growth, volume expansion, and active material loss, stemming from interphase instability, continue to limit battery performance and commercial viability under demanding conditions. The solid electrolyte interphase (SEI) plays a key role in controlling battery stability and lifespan. In addition to the naturally formed SEI, fabrication of artificial SEI (Art-SEI) was effective to enhance interphase stability. This review will analyze and highlight the evolution, formation, and ion transport mechanisms of SEI, along with rational design strategies and the correlation between structure and performance. The structural composition, growth behavior, and ion migration processes of Art-SEI are outlined. Recent advances in characterization and computational methods are summarized to elucidate microstructural evolution, component distribution, ion transport pathways, and interfacial compatibility. These insights provide a guideline for the design of Art-SEI with tailored structures and properties for high-performance LIBs.