Ti3C2Tx@Polyvinyl alcohol foam-Supported Phase Change Materials with Simultaneous Enhanced Thermal Conductivity and Solar-Thermal Conversion Performance

Abstract The phase change materials (PCMs) are attractive and environmental-friendly way to improve the utilization rate in the field of photothermal conversion and solar radiation storage. However, the low photothermal conversion efficiency and low thermal conductivity characteristics of PCMs limit their practical applications. In order to improve the performance of these materials, we developed a novel polyethylene glycol (PEG 2000) PCMs composites supported by Ti3C2Tx@polyvinyl alcohol (PVA) foam skeleton with several advantages like low-cost, scalable and simple preparation method by freeze-drying after PEG being introduced into the skeleton via vacuum impregnation. The thermal conductivity of Ti3C2Tx/PEG composite containing 7.68 wt% skeleton was notably high as 0.428 W/(m·K)，which was 4.2 times higher than PEG 2000 (0.101 W/(m·K)). The improvement of thermal conductivity was mainly derived from the three-dimensional interconnected structures of the foamy skeleton. The actual phase change enthalpy of composite searched up to 131.1 J/g, and its photothermal conversion efficiency achieved 96.5%, demonstrating excellent photothermal conversion and storage ability. Furthermore, the Ti3C2Tx/PEG composite exhibited structural stable property that avoids leakage of liquefied PCM during melting process. This multifunctional Ti3C2Tx@PVA/PEG PCM provided a prospective application in thermal energy management systems regarding its high thermal conductivity, excellent photothermal conversion efficiency, thermal energy storage (TES) capability and structural stability.