CNTs composite aerogel incorporating phase-change microcapsules for solar-thermal conversion and energy storage

Solar energy is an inexhaustible resource. Vigorously developing solar energy can effectively reduce dependence on fossil fuels, thereby improving energy security in countries or regions. However, the application of conventional photothermal materials is limited due to low solar thermal conversion efficiency and the difficulty of preservation. To make use of solar energy, a new phase-change composite material (CNTs-MSA) based on carbon nanotubes (CNTs)-loaded silica aerogel (SA) and microcapsule phase-change materials (MPECMs) was developed by sol-gel and ambient drying. MEPCMs utilize n-octadecane as a phase-change material, which exhibits a enthalpy of 170 J/g and an encapsulation efficiency of 72 %, while also demonstrating stability in retaining their fundamental properties after 200 cycles. Furthermore, the introduction of CNTs not only did not change the lightweight of the aerogel (density is about 0.3 g/cm 3 ), but also greatly improved the compressive strength (the compression stress at 40 % strain reaches 0.9 Mpa). The combination of CNTs and MEPCMs significantly enhanced the solar absorption (14 times than SA) and energy storage capacity (enthalpy of 119 J/g) of the entire composite aerogel material with 75.3 % photothermal conversion efficiency. Such materials will provide a feasible solution to the problem of energy shortage in remote areas, slowing down the over-exploitation of non-renewable energy and promoting environmentally sustainable development.