Realization of highly thermally conductive radiative cooling paint

Abstract

The development of radiative cooling paint that combines high thermal conductivity with high solar reflectance is crucial for efficient heat dissipation. However, realizing such a paint has been challenging due to the low thermal conductivity of commonly used scatterers and polymer matrices. In this work, we have successfully demonstrated a highly thermally conductive radiative cooling paint using beryllium oxide (BeO) particles as the scattering pigments. The coatings with optimized BeO content exhibit excellent thermal and optical properties, with a through-plane thermal conductivity of 4.5 Wm⁻¹ K⁻¹, solar reflectance exceeding 95%, and thermal emissivity of 0.94. The key engineering achievement was optimizing the filler content to establish a two-phase regime, where the fillers are fully embedded in the polymer matrix without the presence of air voids. Our field tests confirmed the coating’s excellent cooling performance under direct solar irradiation of ~ 1000 W m⁻², achieving a cooling temperature of around 5.6 °C. We believe this work offers valuable insights for the development of highly thermally conductive radiative cooling paints with efficient cooling performances.