Unveiling Localized Heat in Lithium‐Ion Cells for Intelligent Temperature Sensing

Lithium‐ion batteries (LIBs) power electric vehicles, portable electronics, and grid‐scale storage, yet their safety, performance, and lifetime are constrained by thermal effects. The mechanisms of heat generation and its spatial distribution within single cells remain insufficiently resolved, limiting effective monitoring. Thermal heterogeneity accelerates capacity fade, drives localized degradation, and elevates the risk of thermal runaway (TR), particularly in high‐energy‐density and fast‐charging systems. This perspective reviews recent advances in elucidating heat generation in LIBs and the manifestation of in‐plane and through‐thickness temperature gradients, emphasizing their influence on electrochemical behavior and safety. Approaches to temperature monitoring are critically assessed, including surface‐mounted and embedded sensors, indirect diagnostic methods, and data‐driven prediction techniques. Future directions are outlined for intelligent, multiscale thermal sensing that integrates advanced sensor technologies with predictive modeling to enable proactive thermal management, thereby enhancing the safety, reliability, and efficiency of next‐generation LIBs across automotive, aerospace, and stationary applications.