High Water-Absorbent and Phase-Change Heat Dissipation Materials Based on Super-Aligned Cross-Stack CNT Films

Carbon nanotubes (CNTs) with the advantage of high thermal conductivity and light weight can be widely used in thermal management. Meanwhile, heat removal for hot spots has become a major issue in the development of electronics because of the increasing of power density and thermal load. Therefore, more effective heat dissipation approaches are needed. Here, the high water-absorbent and phase-change heat dissipation materials based on super-aligned cross-stack CNT (CSCNT) films with excellent cooling performance are reported. Pure CSCNT and CaCl2/CSCNT composite show the outstanding water absorption property because of their high specific surface area and porosity. Combined the high natural convection and heat radiation of CSCNTs with heat removal by water evaporation, the heat dissipation coefficient of CaCl2/CSCNT can reach as high as 98 W m(-2) K-1 with the help of auxiliary plate. Due to the high absorption rate, the composite can absorb water when electronics are at low power and dissipate heat by water evaporation at high power. Moreover, it is founded that there is a dynamic balance of water absorption and desorption to enhance cooling performance at thermal equilibrium.