Shape-stabilized phase change materials supported by eggplants-derived porous carbon for efficient solar-to-thermal energy conversion and storage
In order to effectively solve the leakage problem and insufferably low thermal conductivity of organic phase change materials (PCMs), three-dimensional (3D) spongy-like biological porous carbon (BPC) materials derived from eggplants were used as scaffolds for encapsulating polyethylene glycol (PEG) to fabricate shape-stabilized composite phase change materials (ss-CPCMs). The relationship between the micro-morphology of the BPC and the heat storage performance was discussed by controlling the post-pyrolysis temperature to regulate the micro-morphology of carriers. It is found that the BPC consisting of nanopores and macropores with an average diameter of about 44.758 μm extends a high PEG loading (up to 90.1 wt%), while the hierarchical pores can prevent liquid leakage, enabling the melting enthalpy up to 149 J/g. The ss-CPCMs also have excellent thermal cycling properties with a 96.3% retention after 50 cycles. In addition, the hierarchically porous structure of the BPC provides a good network channel for the thermal motion of phonons, which significantly improves the thermal conductivity. Moreover, as an effective photon captor and molecular heater, it meaningfully improves the solar-to-thermal conversion efficiency of PCM composites. Therefore, the BPC with hierarchical scaffolds and excellent thermal conductivity derived from biomass provides promising applications in PCMs via a low-cost and easy preparation process.