Effects of carbonization temperature on the thermal characteristics of shape-stable composite phase change materials based on silica aerogel

As a solution to the conflict between energy supply and demand, phase change materials (PCMs) could preserve and release energy. However, traditional PCMs suffer from low thermal conductivity and photo-thermal conversion efficiency. This paper reported a method to prepare carbonized polydopamine (PDA)-modified silica aerogel-based (CPS) shape-stable composite phase change materials (ss-PCMs) via carbonizing PDA coating at different temperatures in order to increase the thermal conductivity and photo-thermal conversion efficiency of composite PCMs. The ss-PCMs made from the carrier materials prepared by carbonization at 400, 600, and 800 °C compounded with polyethylene glycol (PEG) were named PEG/400CPS, PEG/600CPS, and PEG/800CPS respectively. It was found that the carbon layer-modified silica aerogel carriers with excellent three-dimensional (3D) porous structure could more effectively absorb the molten PEG (reach 75 %). Particularly, the carbonization temperature was found to determine the degree of carbonization of PDA. When the carrier carbonization temperature reached 600 °C, PEG/600CPS demonstrated a relative thermal efficiency of 97.7 %, with the greatest thermal cycling performance and photo-thermal conversion performance among the series of ss-PCMs created. In this work, our study provided valuable insight into the design of high-performance CPS-based ss-PCMs and demonstrated the manner in which they could be utilized for solar energy storage.