Asymmetric structure endows thermal radiation and heat conduction in graphene films for enhancing dual-mode heat dissipation

To prevent heat accumulation generated by high power components inside a spacecraft, it is necessary to encapsulate a heat dissipation material on the exterior surface of the spacecraft to homogenize local "heat point" and subsequently transfer it to outer space. Hence, developing a flexible heat dissipation material with superior thermal radiation characteristics and thermal conductivity is essential for spacecraft thermal management in a vacuum environment. However, traditional heat dissipation materials fail to simultaneously satisfy these requirements. Herein, we designed a double-layer asymmetric structure to achieve dual-mode heat dissipation in a graphene film, which is verified through finite element analysis (FEA). As the thermal radiation layer, unique rose-like graphene with numerous defects can stimulate plasmon resonance, which can effectively capture incident infrared waves and make multiple reflections until the energy is fully absorbed. The high emissivity reaches 0.99 like that of a blackbody across a wide wavelength range (2.5-18 mu m). As the thermal conductive layer, the orderly lattice structure facilitates the fast transfer of phonons, ensuring a high thermal conductivity of 1196 W m-1 K-1. These properties result in a better cooling effect than that offered by a single graphene film. This work provides a new strategy for designing composites with high thermal conductivity and infrared emissivity for spacecraft thermal management.