Flame-retardant and solid-solid phase change composites based on dopamine-decorated BP nanosheets/Polyurethane for efficient solar-to-thermal energy storage

Abstract

For utilisation of solar energy, the development of form-stable phase change material (PCM) composites with excellent flame retardancy and superior solar–thermal conversion performance is critical. Here, by incorporating dopamine-decorated black phosphorus nanosheets (PDA@BP) into polyethylene glycol-based polyurethane (PEG-PU), novel form-stable PCM composites (PBPCMs) having superior solar–thermal conversion performance and excellent flame retardancy were fabricated. PDA@BP, covalently bonded to PEG-PU, acted as an efficient photothermal filler to capture solar energy and convert it to thermal energy, while PEG-PU absorbed and stored the thermal energy via phase transition. A light irradiation experiment and thermal conductivity test demonstrated that introducing PDA@BP effectively improved the solar–thermal conversion efficiency (up to 88.5%) and thermal conductivity (69.4% increase) of PCM composites. Moreover, by introducing PDA@BP into PBPCMs, the total heat release and heat release rate decreased considerably, while the limiting oxygen index value and char yield increased, demonstrating the considerably enhanced flame retardancy of PCM composites. PBPCMs with superior solar–thermal conversion performance and excellent flame retardancy show considerable potential in the solar–thermal conversion and storage field.