Development and Environmental Assessment of a Phase Change Material Based Thermal Management System for Na/NiCl2 Batteries

The sodium/nickel chloride battery (Na/NiCl2) is considered an eco-friendly, long-term stable and safe alternative to other secondary battery technologies. The overall system efficiency of this high-temperature battery can be increased by optimizing the thermal management system. This paper addresses the integration of a phase change material (PCM) into the battery modules and evaluates the thermal performance and environmental impact of such a design. The module layout with PCM and heat transfer elements (HTEs) was selected based on 2D FEM simulation results and verified in a prototype Na/NiCl2 module. It was shown that the module temperatures could be kept within the operating limits during operation by the HTEs and the PCM even at high current rates. Since no critical temperature limits were reached, the usable battery capacity was higher compared to results of a reference module without PCM or HTEs. In addition, the PCM prolonged the cooling down process after discharge. In parallel with the experimental studies, the environmental performance of the battery was evaluated using a life cycle assessment (LCA). Amongst other things, it was found that the application of PCM is also beneficial from an ecological point of view.