Preparation and light-to-heat conversion efficiency of paraffin/graphene aerogel shape-stable phase change materials

A kind of shape-stable phase change materials (SSPCMs) was prepared by using graphene aerogel (GA) with different pore size adsorbing molten paraffin wax via vacuum impregnation. The characteristics of SSPCMs were determined by scanning electron microscopy (SEM), X-ray diffractometer (XRD), differential scanning calorimetry (DSC) and TCi thermal conductivity analyzer. The SSPCMs possessed a high comprehensive performance: a high thermal conductivity of 1.432W/m.K (more than 400% increase over pure paraffin), a good capacity of thermal energy storage (more than 200 J/g), a ability to light-to-heat energy storage and coating effect (encapsulation ratio is about 55%) due to the three-dimensional GA foam structure with functions of thermal conductivity and adsorptive property. In addition, an energy conversion from light to heat was realized with the SSPCMs. For different morphologies of GA, as pore size of GA decreases, SSPCMs' thermal conductivity and solar energy usage efficiency increases and their leakage rate reduces. This means that pore size of GA can influence the properties of SSPCMs to some extent.