Effects of graphene doping on shape stabilization, thermal energy storage and thermal conductivity properties of PolyHIPE/PEG composites

Abstract

The development of clean and renewable energy sources has been necessitated by the ever-increasing energy consumption, increasing environmental degradation caused using fossil fuels and concerns over the rise in CO2 spreading. Functional phase change materials (PCMs)' energy storage capacity is appealing owing to their environmental friendliness, superior thermal energy storage (TES) capacity, and capability to improve energy efficiency. A series of hierarchical porous high internal phase emulsion polymer (PolyHIPE) materials with high PCM impregnation capacity were synthesized in this investigation. It has been achieved to encapsulate 80 % by mass of polyethylene glycol (PEG) into the PolyHIPE structure. However, the efficiency of energy storage and conversion systems is affected by a wide variety of factors; one of them is poor thermal conductivity. The development of carbon-based materials like graphene is particularly promising in the disciplines of energy storage and conversion. With this intention, the synthesis of composite PCMs in which the heat conductivity has been enhanced with graphene at three different ratios (wt% 3, 5, and 10) has been performed, conducting comprehensive investigations. The produced composite PCMs have an energy storage capability of over 120 J·g−1 and high thermal and structural stability. In the polyHIPE/graphene structures produced in the absence PCM, the thermal conductivity value exhibits a notable enhancement of up to 125 % due to the increased amount of graphene compared to the polyHIPE material. Following the impregnation of PolyHIPE@Graphene with PEG, it was observed that the thermal conductivity value improved by up to 51.2 % in comparison to PCM. The addition of graphene also gradually shortened the heat storage-release time. In short, herein a series of PCM composites with high energy storage capacity, capable of trapping different PCMs within their structure, has been proposed for TES applications. The manufactured composite PCMs have the potential to be used for a wide range of things, like maintaining the temperature of batteries and photovoltaic solar cells, packaging perishable foods, and providing thermal comfort in textiles and medicinal materials.