Multiscale Modeling and Validation of Thermal Runaway Propagation in Immersion-Cooled Battery Systems with Full-Scale Application

<div class="section abstract"><div class="htmlview paragraph">Thermal management is a key challenge in the design and operation of lithium-ion batteries (LIBs), particularly in high-stress conditions that may lead to thermal runaway (TR). Immersion cooling technology provides a promising solution by offering uniform cooling across all battery cells, reducing the risk of hotspots and thermal gradients that can trigger TR. However, accurately modeling the thermal behavior of such systems, especially under the complex conditions of immersion cooling, presents significant challenges.</div><div class="htmlview paragraph">This study introduces a comprehensive multiscale and Multiphysics modeling framework to analyze thermal runaway and its propagation (TRP) in battery systems cooled by immersion in dielectric fluids. The model integrates both 1D and 3D simulations, focusing on calibrating energy terms at the single-cell level using 3D Computational Fluid Dynamics (CFD). The calibration process includes a detailed analysis of cell chemistries, exothermic heat release, and thermal runaway onset temperatures, all based on experimental data.</div><div class="htmlview paragraph">The electrochemical processes within the cells are modeled using the Pseudo 2D (P2D) approach, incorporating key side reactions that may trigger thermal runaway. Thermo-mechanical processes and gas venting are also considered to simulate pressure build-up and thermal abuse reactions at elevated temperatures. Initial validation of the TRP model is performed using a 7-cell battery module, comparing performance in air and dielectric fluid environments.</div><div class="htmlview paragraph">The model is further applied to a full-scale battery module, providing a detailed analysis of TRP under realistic conditions. The simulations demonstrate strong alignment with experimental data, underscoring the effectiveness of immersion cooling in delaying or mitigating TRP and enhancing battery safety.</div><div class="htmlview paragraph">By addressing the complexities of thermal management in immersion-cooled LIBs, this work offers valuable insights for improving battery design and safety, guiding future research and development of next-generation battery technologies.</div></div>