Aluminum and silicon based phase change materials for high capacity thermal energy storage

Six compositions of aluminum (Al) and silicon (Si) based materials: 87.8Al-12.2Si, 80Al-20Si, 70Al-30Si, 60Al-40Si, 45Al-40Si-15Fe, and 17Al-53Si-30Ni (atomic ratio), were investigated for potentially high thermal energy storage (TES) application from medium to high temperatures (550-1200 °C) through solid-liquid phase change. Thermal properties such as melting point, latent heat, specific heat, thermal diffusivity and thermal conductivity were investigated by differential scanning calorimetry and laser flash apparatus. The results reveal that the thermal storage capacity of the Al-Si materials increases with increasing Si concentration. The melting point and latent heat of 45Al-40Si-15Fe and 17Al-53Si-30Ni are ∼869 °C and ∼562 J g−1, and ∼1079 °C and ∼960 J g−1, respectively. The measured thermal conductivity of Al-Si binary materials depend on Si concentration and is higher than 80 W m−1 K−1 from room temperature to 500 °C, which is almost two orders of magnitude higher than those of salts that are commonly used phase change material for thermal energy storage.