Bifunctional nanoencapsulated eutectic phase change material core with SiO2/SnO2 nanosphere shell for thermal and electrical energy storage

Abstract

A novel bifunctional nanoencapsulated phase change materials (NEPCMs) were synthesized based on oleic acid (OA) - polyethylene glycol (PEG) core with SiO2/SnO2 shell via in situ emulsion interfacial hydrolysis and polycondensation followed by successive ionic layer adsorption and reaction method. Microscopic analysis reveals the uniform formation of SnO2 as mild-flower like structure on the surface of SiO2 nanocapsules. The chemical functional groups of NEPCMs were deduced by fourier transform infrared spectroscopy. The crystalline nature and structure of NEPCMs were analyzed using x-ray diffraction analysis. Thermal property (heat transfer rate of 0.7053 Wm−1 K−1), electrical property (electrical conductivity of 1.08 × 10−7 S/cm) and electrochemical performance (specific capacitance of 59.2 F/g) were analyzed. Melting/solidification at 3.11, 2.57 °C with a latent heat of 58.79, 55.49 J/g and an encapsulation ratio of 52.12% were observed for OA-PEG/SiO2/SnO2 NEPCMs by differential scanning calorimetry. Thermogravimetric analysis recorded the enhanced thermal stability of NEPCMs. The yield load and hardness was determined as 89.65 ± 3 μN, 4.7 ± 0.3 GPa using a nanoindenter. Based on all results, the bifunctional NEPCMs can be used as shape-stabilized phase change materials for cold thermal energy storage (CTES), and in cooling functions for electronic chips as well as promising electrode materials for electrochemical energy storage.