Suitability of Aluminium-Copper-Silicon as metallic Phase Change Material for the usage in battery electric vehicles

Abstract

Thermal energy storage systems offer energetic potentials concerning the usage in electric vehicles. These potentials include the storage and usage of waste heat from the charging process of the traction battery as well as a thermal preconditioning of the storage. Thus the electric driving range can be extended and the driving comfort is increased. Well known thermal energy storage systems for the usage in vehicles are mainly based on sensible water storages, on latent heat storages by using salts or paraffins or on thermochemical storages. Despite the specific unique advantages each storage technology shows the vehicle specific requirements on thermal performance, specific energy density and cost-value ratios are usually not achieved until now. Against this backdrop, the DLR Institute of Vehicle Concepts is focusing on the use of new energy materials for the use in vehicle specific thermal storage systems, so called metallic Phase Change Materials (mPCM). By using these new materials, the main requirements on thermal storage systems for vehicle application, like a high specific energy density and a high thermal in- and output can be achieved. One promising candidate for a suitable mPCM is the ternary alloy Aluminium-Copper-Silicon. The suitability of this alloy as mPCM for vehicle application is discussed. Therefore, the requirements and boundary conditions for vehicle specific thermal energy storage materials are given. Subsequently, the characteristic properties of mPCM are introduced and the determination of the relevant thermophysical quantities of Aluminium-Copper-Silicon will be focused. The relevant quantities include specific heat capacity, heat of fusion and temperature of fusion determined by calorimetric methods as well as the thermal diffusivity determined by Laser-Flash-Analysis. Finally, the fulfillment of the before introduced requirements and the performance of the alloy as mPCM for vehicle application are reviewed.