Thermal Safety Frontiers in Electrochemical Energy Storage: Thermal Runaway Mechanisms, Intelligent Sensing, and Multiscale Suppression Strategies

Abstract With the continuous pursuit of high energy density in electrochemical energy storage systems, the thermal safety of lithium-ion batteries has emerged as a critical bottleneck restricting their large-scale application. This article systematically reviews the frontier advances in the field of lithium-ion battery thermal safety, innovatively establishing a comprehensive knowledge framework spanning from microscopic mechanisms to macroscopic system-level protection. First, it provides an in-depth analysis of the triggering mechanisms of thermal runaway and the cross-scale chain reaction evolution pathways, summarizing mechanism-based and data-driven modeling and prediction methods. Second, it focuses on real-time intelligent monitoring and early warning technologies for thermal runaway, constructing a full-process technical system covering “sensing-identification-warning”. In terms of cell-level protection, it systematically outlines the paradigm evolution of cell materials from traditional passive protection toward active-response approaches. Finally, it discusses thermal management and engineering protection strategies at the system integration level, summarizing the critical pathways for enhancing system safety design and failure response capabilities. This review aims to provide a systematic theoretical perspective for resolving the inherent trade-off between energy and safety in high-energy-density batteries and to offer comprehensive theoretical insights and innovative technological pathways for the next generation of energy storage systems.