A Critical Assessment of Phase Change Materials for Boosting EV Efficiency

Effective thermal management in battery packs is a key technology for enhancing the efficiency and longevity of battery electric vehicles (BEVs). Traditional active cooling systems can consume significant amounts of energy, thereby impacting the vehicle's overall efficiency. This paper explores the use of phase change materials (PCMs) as a complementary cooling technology, enabling both an improved active and an extended passive conditioning of battery packs. By leveraging the unique properties of PCMs, it is possible to partially operate the battery system without active cooling, thus reducing the overall energy consumption and improving vehicle autonomy. The phase change phenomenon further offers the benefit of a homogeneous temperature distribution within the battery pack. This study addresses the potential of PCMs as a thermal management solution for battery packs by firstly identifying suitable materials meeting requirements specific to such application. In addition, the paper investigates the expected benefits of such a cooling strategy by employing a dedicated modeling approach considering heat generation and distribution for analyzing the thermal behavior of an exemplary battery pack. We compare the thermal behavior to the case of polyurethane foams typically utilized as an intercell material. For the PCM identified as most suitable in this study, we find an increase of the operation time without the need for active cooling of up to 80 % in the framework of consecutive WLTP cycles. The contribution discusses challenges and potential drawbacks of integrating solid-solid and solid-liquid PCMs into battery packs, regarding pack weight, costs as well as the impact on thermal propagation and pack design related to the volumetric expansion of the PCM. Through this, the paper aims to provide a comprehensive understanding of the feasibility and implications of using PCMs as a complementary solution on the path to highly efficient battery pack thermal management.