Mechanically strong hectorite aerogel encapsulated octadecane as shape-stabilized phase change materials for thermal energy storage and management

Abstract

Phase change materials (PCMs) are considered one of the most advanced energy-saving materials owing to their high thermal energy storage density during the phase transition process. To solve the leakage problem and poor thermal properties in PCMs, a three-dimensional (3D) hectorite aerogel, with an abundant porous structure, was synthesized to encapsulate octadecane (ODE) for preparing hectorite/octadecane composite PCMs with shape stability, large latent heat capacity, and good mechanical strength. The mechanical and thermophysical properties of the composite PCMs were investigated in depth in this study. Due to the high porosity characteristic of hectorite aerogel, the composite PCMs exhibited a large latent capacity of 196.70 J/g with an ODE loading rate larger than 85 wt%. It was also found that the aerogel played an important role in maintaining shape stability, as no significant leakage was observed during the phase-change process. In addition, the composite PCMs exhibited a compressive strength of approximately 2.4 MPa, suggesting good mechanical strength. The thermal stability was found to be excellent, considering that the thermal decomposition temperature of the composite was far higher than the phase change temperature. The excellent shape stability and thermal stability contributed to the outstanding recycling performance of the composite PCMs. The thermal management performance of the composite, in a building house model, was also tested to verify its superior thermal regulation function. Thus, these mechanically strong composite PCMs, with stupendous energy storage capacities and good form stabilities, can be applied in the energy storage and thermal management fields, thereby showing great potential for a sustainable society.