Route to design highly efficient thermal rectifiers from microstructured cellular biomorphic materials

The application of electronic diodes has greatly motivated the development of industrial engineering, while predictably, thermal rectifiers, as thermal manipulation devices, might have broad applications in the renewable energy engineering. Here, we report a significant thermal rectification phenomenon observed by using a thermal rectifier solid-state device comprising microstructured cellular biomorphic materials and by measuring the thermal conductivities in the forward and reverse directions over a wide temperature range. Our theoretical studies, based on analytical method and simulation of finite element method, attributed the asymmetry of thermal transition in opposite directions to the microstructured cellular size-gradient geometry. We further demonstrated that the thermal rectification phenomenon was only observed when the thermal conductivity of the filled materials showed monotonic temperature dependence. Our present work suggests a convenient and practical route to design a highly efficient thermal rectifier by increasing the cellular size gradient or using materials with larger thermal conductivity to temperature ratios.