Double-layered and shape-stabilized phase change materials with enhanced thermal conduction and reversible thermochromism for solar thermoelectric power generation

Energy conversion technologies and systems associated with phase change materials (PCMs) have gained great popularity recently. How to convert the heat captured from solar energy into applicable electricity is significant and challenging, in particular for stable power output. Given that three-dimensional (3D) structural scaffold can ameliorate shape stability and thermal conductivity simultaneously, a novel double-layered multifunctional 3D hybrid scaffold is developed through two-step freeze-casting to produce leakage-proof photodriven composite PCMs with enhanced thermal conductivity for efficient light-thermoelectric conversion. The as-prepared double-layered scaffold is composed of black bacterial cellulose (BC)/thermochromic particle (TP) upper layer with the function of reversible photoabsorption and white BC/boron nitride (BN) lower layer with the function of heat conduction. The resultant leakage-proof composite PCMs exhibit high thermal conductivity up to 3.26 W/(mK) at a BN loading of 16.3 vol% and improved reversible photoabsorption ability. When used as heat source in a light-thermoelectric power generation system, a long-term stable output voltage of 287 mV is generated, achieving effective conversion from renewable solar energy to applicable electricity.