Directional thermal conductive PEG@BNNS composites enhanced tri-function passive radiative cooler for thermal management of high-power density devices

The increasingly powerful computing capabilities of 5G technology are posing greater heat dissipation challenges for communications base stations. Passive radiative cooling, as a promising cooling strategy without energy consumption, however, is severely limited by its insufficient cooling power especially in the face of high heat flux conditions. Herein, we report a tri-function passive radiative cooler (TPRC) to enhance the cooling capacity through the synergistic effect of broadband radiative cooling, latent heat storage, and directional thermal conduction. Vacuum-assisted self-stacking, skeleton absorption and coating methods are used to fabricate TPRC. Under the heating power density of 4000 W/m², TPRC lowered the thermal equilibrium temperature to 74.1 °C, a reduction of 16 °C and 3.7 °C compared to the bare aluminum plate and single radiative film, respectively. The contributions of these three cooling types were analyzed and it revealed that optimizing thermal conduction can effectively improve cooling efficiency. Our work provides a comprehensive strategy for expanding the application of passive radiative cooling to high power density devices.