Design of PVA/multilayer hybrid particle composite aerogel skeleton supported form-stable phase change materials with high thermal conductivity and solar-to-thermal conversion efficiency

Phase change materials (PCMs) are considered to be promising energy storage materials, but the advanced utilization of PCMs is limited by liquid phase leakage, low thermal conductivity and poor solar-to-thermal conversion ability. Herein, inspired by the structure of nacre, we used boron nitride nanosheets (BNNs) coated with polydopamine (PDA)-modified tetrapod zinc oxide (T-ZnO) to prepare multilayered BNNs/PDA@T-ZnO hybridized particles (BPT), and then employed them to reinforce the PVA aerogel to obtain a BPT/PVA skeleton. Due to the robust support of T-ZnO substrate, BPT/PVA skeleton has ordered porous structure and excellent mechanical properties, with compressive strength up to 15.7 MPa. The prepared composite PCMs of polyethylene glycol (PEG) supported by BPT/PVA skeleton (PVA/BPTs/PEG) have good heat storage capacity, thermal conductivity and solar-to-thermal conversion efficiency. The rigid BPT/PVA skeleton endows PVA/BPTs/PEG with good shape stability and durability, whereas the melting enthalpy and crystallinity of PVA/BPT/PEG reach 139.0 J·g−1 and 99.6 %, respectively. The intermediate dopamine layer of BPT acted as an adhesive for BNNs and T-ZnO and excellent solar-to-thermal conversion medium, which cause the PVA/BPTs/PEG composites to have excellent solar-to-thermal conversion efficiency (95.2 %). Meanwhile, the thermal conductivity of PVA/BPTs/PEG reach 1.34 W·m−1·K−1, benefiting from the continuous 3D heat transfer path provided by the stacked BPT particles. Considering the outstanding overall performance, the prepared composite PCMs have the potential to be suitable for the application of high efficiency thermal management and solar energy utilization.