Photodriven Shape-Stabilized Phase Change Materials with Optimized Thermal Conductivity by Tailoring the Microstructure of Hierarchically Ordered Hybrid Porous Scaffolds

Graphene oxide (GO)/boron nitride (BN) hybrid porous scaffolds (HPSs) with the optimally three-dimensional (3D) aligned network structure are fabricated using an unidirectional ice-templated strategy. A variety of HPSs with multilayer structure are obtained due to the various temperature gradients generated by tuning freezing temperature, in which GO and BN are expelled from the ice growth front to assemble between the oriented ice crystals. We demonstrate that the obtained HPSs have a significant influence on the properties of the resulting composite phase change materials (PCMs), including thermal conductivity and shape-stability. Various thermally conductive pathways are formed by tuning freezing temperature, which contributes to further understanding the relationship between thermal conductivity of composites and their internal network structure. Upon increasing the freezing temperature from −120 to −30 °C, the thermal conductivity of the composite PCMs increases and reaches a maximum value at −50 °C and then decreases with a further increase in freezing temperature to −30 °C. The resultant composite PCMs exhibit a high thermal conductivity (3.18 W m^–1 K^–1) at a relatively low BN loading of ca. 28.7 wt %, maintaining high package capacity (ca. 72 wt %) and energy storage density. Furthermore, the composite PCMs also present excellent thermal reliability and realize an efficient solar energy conversion. This strategy provides an insight for the design of high-performance composite PCMs with potential to be used in advanced thermal management and energy conversion systems