Energy Conversion Efficiency Enhancement of Polyethylene Glycol and a SiO(2) Composite Doped with Ni, Co, Zn, and Sc Oxides

[Image: see text] Doping the SiO(2) support with Co, Ni, Zn, and Sc improves the thermal conductivity of a hybrid PEG/SiO(2) form-stable phase change material (PCM). Doping also improves the energy utilization efficiency and speeds up the charging and discharging rates. The thermal, chemical, and hydrothermal stability of the PEG/Zn-SiO(2) and PEG/Sc-SiO(2) hybrid materials is better than that of the other doped materials. The phase change enthalpy of PEG/Zn-SiO(2) is 147.6 J/g lower than that of PEG/Sc-SiO(2), while the thermal conductivity is 40% higher. The phase change enthalpy of 155.8 J/g of PEG/Sc-SiO(2) PCM is very close to that of the parent PEG. PEG/Sc-SiO(2) also demonstrates excellent thermal stability when subjected to 200 consecutive heating–cooling cycles and outstanding hydrothermal stability when examined under a stream at 120 °C for 2 h. The supercooling of the PEG/Sc-SiO(2) system is the lowest among the tested materials. In addition, the developed PCM composite has a high energy storage capacity and high thermal energy storage/release rates.