VO2-based first-order phase change thermally rectifying materials

Asymmetric structures play a significant role in optimising the thermal rectification effect. In this study, non-equilibrium molecular dynamics simulations were used to investigate the thermal rectification of vanadium dioxide (VO₂) with nano-scale asymmetric structures. It is found that the pore structure affects thermal conductivity before and after the phase transition, and an asymmetric gradient porous structure can effectively enhance thermal rectification performance. With 9 Å pores, the ratio of the thermal conductivity of VO₂ before and after phase transition can reach 1.75, which is approximately 9.4% higher than that of pure VO₂. Meanwhile, the ratio of thermal conductivity before and after phase transition of the 7 Å and 5 Å pore structures also increased by approximately 7.5% and 5.1%, respectively. At the device level, a thermal diode was also constructed from VO₂ with an asymmetric structure for thermal rectification. The results show that the maximum thermal rectification ratio can reach 1.39 with a small temperature difference of 30 K.