Predictive Thermal Safety of Lithium-Ion Batteries through a Unified Kinetic-Thermal Framework

Abstract

Thermal runaway remains a critical barrier to the safe deployment of high-energy lithium-ion batteries. Here, we establish a unified quantitative framework that integrates intrinsic reaction kinetics with thermal transport to predict and design cell-level thermal safety.Accelerating rate calorimetry measurements are employed to resolve temperature-dependent selfheating behaviors across state of charge, providing direct inputs for a physics-based thermal model that captures both internal conduction and boundary convection. Systematic variation of state of charge, surface-to-volume ratio, and convective intensity reveals a distinct critical temperature separating stable and runaway regimes, enabling construction of a comprehensive thermal safety boundary. We show that the surface-to-volume ratio, rather than aspect ratio, serves as the fundamental geometric parameter governing temperature uniformity and heat dissipation. A dimensionless thermal safety criterion is further derived, explicitly linking self-heating to dissipation and allowing direct estimation of safe operating limits without reliance on full CFD simulations. This framework transforms thermal safety evaluation from empirical observation to a predictive, physics-informed design methodology, bridging mechanistic understanding and engineering practice to guide safe operation and scalable thermal management of lithium-ion batteries across chemistries, geometries, and cooling configurations.