Heat transfer model for temperature-sensing polymer composite EV battery enclosure

Abstract

Increased decarbonization efforts have led to greater Electric Vehicle (EV) adoption, with Lithium-Ion Batteries (LIBs) as the primary energy storage system. While generally safe, these batteries are susceptible to a catastrophic failure mode called thermal runaway, which can result in battery fires and explosions. To improve EV safety, a novel self-contained temperature-sensing LIB enclosure was proposed, functioning independently of other management systems. This study designed a Fiber Reinforced Polymer (FRP) composite enclosure to replace traditional metal ones, reducing weight while enabling temperature sensor embedment during manufacturing. Embedding sensors inside the composite mitigates space constraints and protects hardware but introduces a time lag in detecting internal temperature surges. This study characterizes that time lag through experiments and develops an accurate heat transfer model. A novel experimental setup was designed to replicate thermal runaway conditions, both thermal shock (fast surges) and thermal ramp-up (slow increases), on a temperature-sensing composite specimen. The experiments provided data for model calibration and validation. The 3D finite element heat transfer model was developed to study temperature propagation in composites with embedded sensors, considering anisotropic material complexities and transient boundary conditions. This model aligned well with experimental results, yielding mean absolute percentage errors below 0.065 %. It serves as a robust tool for simulating composite temperature responses under diverse thermal runaway scenarios. Additionally, the model was used to determine optimal sensor placement in a temperature-sensing composite enclosure. This study lays the groundwork for future research on inferencing and monitoring LIB enclosure interior temperatures for early thermal runaway warnings.