Enhanced cooling performance of battery packs by using phase-change materials

Batteries are crucial components of electric vehicle, and they represent a large portion of the overall cost of the vehicle, in particular of the electric one. Therefore, it is important to keep the batteries as close as possible to their optimal operating conditions to achieve extended cycle life. Their charging and discharging cycles generate significant heat, which is required to be dissipated to maintain the desired operating temperature range. Outside this range, their efficiency, reliability, and cycle life will deteriorate. To this purpose, it is needed a suitable battery thermal management system, which should satisfy several requirements, among them, temperature control accuracy, light weight, operation simplicity and reliability, low energy consumption, cost, and improved thermal uniformity among battery packs. Among many materials and technologies, phase-change materials (PCMs) are increasingly becoming prime candidates for thermal management systems, as they have the potential of fulfilling the main thermal management requirements, while competing well in terms of cost and energy consumption with current systems. These materials offer the flexibility of being incorporated into active or passive systems, while enabling a wide range of autonomous operation to the battery thermal management system. This book chapter covers the state of the art of management systems in thermal by using PCMs. Promising areas of improvement of such systems are described, in particular, enhanced thermal conductivity of PCMs, thermal management strategies, and new configurations. In particular, by combining PCMs with high thermal conductivity particles, metal fins, metal foam, and extended graphite matrices, it is possible to increase the thermal conductivity of PCMs and, as a result, increase heat transfer. Hybrid systems that integrate PCMs with liquid or air cooling as well as new thermal management topologies, such as sandwiched and multilayer PCMs, are also presented.