A Hybrid Battery Thermal Management System for Electric Vehicle Operations in Cold Climates

Without proper battery thermal management, electric vehicles (EVs) suffer from significantly reduced efficiency and performance in cold climates, creating a barrier to electrifying the transportation sector. In this study, we have developed a modular, hybrid battery thermal management system that combines phase change material (PCM) with internal heating. This hybrid system uses PCM to store waste heat generated during driving, maintaining the battery temperature during shorter stops between consecutive trips. For longer stops, internal heating can re-heat the battery if the latent heat of the PCM has dissipated. Moreover, by applying PCM on the outside, the proposed system is modular, requiring no structural change within the existing battery module and reducing the impact of increased thermal inertia on battery re-heating time. Through both laboratory experiments and numerical simulations, we found that the proposed system could hold the battery temperature above 20°C for around 2 hours at an ambient temperature of −15°C and achieved a battery-reheating time (from 0°C to 20°C) of only 11 minutes. By reusing waste heat during short stops, this system can promote EV adoption in cold climates through improved battery efficiency, particularly for EVs making frequent stops, such as taxis and delivery vehicles.