Predicting battery thermal runaway effects on composite structures using finite element analysis

Composite materials, for lightweighting, and lithium-ion batteries (LIB), for electrification, have expanded significantly in automotive applications. However, Carbon Fibre Reinforced Polymer (CFRP) composites are more susceptible to thermal damage than traditional metallic structures. Thermal runaway (TR) can result in battery fire and its containment remains a prominent safety concern. This work develops a trio of sequential Finite Element (FE) simulations; heat transfer, thermo-mechanical and Compression after Thermal Runaway (CaTR). These simulations predict the heat transfer behaviour, due to heat flux loading, mechanical damage (i.e., fibre/matrix failure or delamination), and finally the CaTR residual strength of the specimen. Model validation is completed for both 18650 and 21700 cells. Results show that multi-cell TR induced damage can potentially reduce the residual compressive strength to around 110 MPa, approximately 20% of its initial strength. The CaTR simulation predicted the residual strength of carbon fiber/polyetheretherketone (CF/PEEK) panels within 7% of the experimental value.