Artificial “honeycomb-honey” decorated with non-noble plasmonic nanoparticles for superior solar capture and thermal energy storage

Phase change materials (PCMs) are popular solutions to tackle the unbalance of thermal energy supply and demand, but suffer from low thermal conductivity and leakage problems. Inspired by how honeybees store honey, we propose artificial “honeycomb-honey” for excellent solar and thermal energy storage capacity based on TiN nanoparticles decorated porous AlN skeletons-PCMs composites. The thermal conductivity of composites achieves 21.58 W/(m·K) at AlN loading of 20 vol.%, superior to the state-of-the-art ceramic-based composites. The charging/discharging time is reduced to about half of pure PCMs with shape-stability and thermal reliability well maintained over 500 melting/freezing cycles. The underlying mechanism can be attributed to the combination of single-crystal AlN whiskers with few crystal defects and reduced phonon scattering, as well as vertically arranged three-dimantional (3D) heat conduction channels. A rapid and efficient solar thermal storage is also demonstrated with solar thermal storage efficiency achieving a high value of 92.9% without employing additional spectrum selective coatings. This is benefited from high thermal conductivity and full-spectrum solar absorptance of up to 95% induced by plasmonic resonances of TiN nanoparticles. In addition, by embedding LiNO₃-NaCl eutectics, the phase change enthalpy of composites reaches as high as 208 kJ/kg, making high energy storage density and fast energy storage rate compatible. This work offers new routes to achieve rapid, efficient, stable, and compact solar capture and thermal energy storage.