Synergistic engineering of smart electrolytes and ultrathin coatings for adaptive interphase formation in advanced batteries

The electrode–electrolyte interphase is a critical determinant of performance and stability in advanced battery systems. However, its uncontrolled formation and dynamic evolution often lead to degradation, limiting practical applications. This review provides a comprehensive overview of recent strategies for interphase regulation through smart electrolyte design and ultrathin surface coatings. We first discuss the fundamental mechanisms of interphase formation, highlighting the roles of solvation structure, interfacial reactions, and mechanical effects. Subsequently, smart electrolyte strategies including high-concentration systems, localized high-concentration electrolytes, functional additives, and adaptive formulations are examined for their ability to direct interphase chemistry. In parallel, ultrathin surface coatings, such as atomic layer deposition films, artificial interphases, polymer coatings, and functional nanolayers, are reviewed for their role in controlling interfacial reactions and enhancing stability. Particular emphasis is placed on the synergistic interaction between electrolytes and coatings, which enables the formation of adaptive interphases with improved uniformity, mechanical integrity, and electrochemical performance. The practical implications of these strategies are further discussed across various battery systems, including lithium metal, high-voltage lithium-ion, and emerging chemistries. Finally, key challenges and future research directions are outlined, focusing on scalability, compatibility, and the development of self-regulating interphases. This review provides insights into the rational design of integrated interfacial systems for next-generation energy storage technologies.