A novel multiwalled LiF@GO@SiO₂ microcapsule with high phase change temperature

High temperature phase change materials (PCMs)-encapsulated microcapsules with large heat exchange area for addressing specific energy storage have increasing application potentials in many fields. Herein, a novel hybrid multiwalled microcapsule LiF@GO@SiO₂ with high phase change temperature was designed and fabricated, which could overcome strong corrosion and volume expansion of lithium fluoride (LiF) during heat storage process. The multiwalled structure of microcapsule contained three layers, consisting of volume expansion buffer layer polydopamine (PDA), anti-corrosion leakage-proof layer (GO) and heat-resist strength layer (SiO₂), respectively. Volume expansion buffer layer would be vanished during thermal cycling, and GO as well as SiO₂ layers played important roles in protecting molten LiF from leakage. A series of tests including SEM, SEM-EDS, FTIR, XPS, XRD and TGA revealed that three-layer shells were sequentially coated on the surface of core material LiF successfully. Besides, DSC results via quantitatively analyzing, indicated that LiF@GO@SiO₂ microcapsules had high phase change temperature of 848 °C, encapsulation ratio of 82.0% and latent melting heat of 894.5 J/g. In addition, encapsulation ratio of the microcapsule had a minor deflection within 5% after 10 times loops by calculating and comparing corresponding enthalpies, which displayed prepared microcapsule could be used repeatedly in high temperature energy storage. Overall, our results opened new avenues for the utilization of high temperature PCMs and their packaging technique.