Numerical Simulation of Thermal Barrier Materials for EV Battery Pack Safety

Abstract

This study develops a computationally efficient framework for screening thermal barrier materials (TBMs) intended to delay thermal propagation (TP) in lithium-ion battery packs for battery electric vehicles (BEVs). A transient one-dimensional heat-conduction model is solved by the implicit finite difference method (IFDM) to predict the temperature evolution through a multilayer TBM-aluminium assembly exposed to a severe jet-fire-like thermal boundary condition. Six TBM concepts, including high- and low-performance intumescent coatings, mica-based laminates, a glass-fiber-reinforced polymer composite with a thermal blanket, a rigid mica-silicone laminate and an ablative material, are represented using effective temperature-dependent thermophysical properties. The novelty of the work is the combination of a stable IFDM formulation, simplified effective-property descriptions of intumescent and ablative mechanisms, and safety-oriented ranking metrics linked to the five-minute evacuation requirement of GB 38031-2020. The results indicate that the 3.5 mm ablative TBM provides the strongest protection, limiting the cold-face peak temperature to 156.7 °C and maintaining a 10.0 min thermal delay. Compared with the worst-performing configurations, this corresponds to an 86.9% reduction in peak cold-face temperature and a 100% positive margin over the GB 38031-2020 delay criterion. The high-performance intumescent coating satisfies the delay requirement marginally, with a 5.1 min delay, whereas thin mica-based and low-performance intumescent solutions fail rapidly. The model is intended as an early-stage design and ranking tool for the VLUTE SMART LI PACK rather than a replacement for full CFD/FEM fire simulations or pack-level abuse tests. Its main limitations are the one-dimensional heat-transfer assumption, the use of effective material properties and the absence of full stochastic validation.