Facile Preparation of Binary Salt Hydrates/Carbon Nanotube Composite for Thermal Storage Materials with Enhanced Structural Stability

Large-scale distributed thermal storage requires high-energy-density and low-cost thermal storage materials. Here, a concocted composite composed of Al2(SO4)3·18H2O and FeSO4·7H2O salts, as well as carbon nanotubes (CNTs) as a thermal conductive agent has been proposed for the applications of large-scale distributed thermal storage. The composite was physically mixed but displayed enhanced structural stability due to the use of carbon nanotubes that formed networks in the composite. The use of CNTs could restrain the volume change of the salt mixture in thermal charge/discharge. The detailed thermophysical properties and thermal energy storage performance were studied, including latent heat, thermal conductivity, and thermal cycling stability. A differential scanning calorimeter (DSC) revealed that the largely endothermic temperature and absorbed heat of the composite were 118.43 °C and 422.40 J g–1, and it also delivered a high stability of ca. almost no capacity fading in exampled 100 cycles. The introduction of the carbon nanotube creates thermal conductivity networks in the composite, endowing the composite material with enhanced thermal conductivities. This can provide rapid thermal storage while retaining the storage density. This study can give insights into the rational design of salt hydrates for thermal storage.