Revisiting Battery Swelling and the Role of Swelling in Performance and Safety: A Perspective

Abstract Swelling in lithium-ion batteries is a multiscale and multiphysics coupled behavior that persists throughout the entire battery lifecycle, impacting design and operation at both the cell and system levels. This article focuses on the role of swelling in battery performance degradation and safety risks, revealing how it acts as a bridge connecting electrochemical degradation and mechanical failure, thereby exacerbating their interaction. This article first analyzes reversible and irreversible swelling mechanisms and then systematically examines the pathways through which swelling induces performance decay and catalyzes thermal runaway. Finally, multilevel mitigation strategies and fundamental paradigm shifts, ranging from materials to mechanisms and intelligent management, are proposed. Understanding and controlling swelling effectively is an essential pathway for constructing next-generation lithium-ion battery systems with high performance and high safety.