Flexible ion-crosslinked vermiculite nanosheet composite phase change materials with high energy storage density and reshapability

Traditional shape-stabilized Phase Change Materials (PCMs) are generally obtained by vacuum impregnation PCM into prefabricated porous supports, and therefore, they have fixed shapes. The preparation process is complicated, and the energy storage density is low. Herein, we report a new synthetic method to obtain vermiculite nanosheets (VNSs) by exfoliation of Expanded Vermiculite (EVM), take metal ions to disrupt the electrostatic repulsion between VNSs, shape in-situ a three-dimensional porous network, and restrict the flow of PEG to obtain VNSs-based composite PCMs. By regulating the size of VNSs to obtain stable thermal properties and adding nano-Al 2 O 3 to increase the nucleation sites to improve the energy storage efficiency and thermal conductivity. The composite PCMs own high energy storage density, up to 90.76 %, high thermal conductivity of 0.47 W/m·K, an increase of 80.77 % compared to pure PEG. At the same time, the composite PCMs are flexible and can be reshaped above the phase transition temperature. It brings a new synthetic method for the preparation of composite PCMs and broadens the application scope of PCMs.