Hard Carbon Nanotube Sponges for Highly Efficient Cooling via Moisture Absorption-Desorption Process

Heat dissipation is a serious limitation for increasingly miniaturized and functionalized electronics, resulting in the continuous need for developing highly efficient cooling methods. Here, utilizing the strong van der Waals force between super-aligned carbon nanotubes (SACNTs), a self-supported three-dimensional (3D) CNT/CaCl₂ radiator with a more outstanding cooling performance than Al cooling fins was designed. Unlike the soft CNT sponges, these 3D structures could sustain a high pressure of 4.5 MPa with a small compression of 10% and thus are defined as hard CNT sponges. Hard CNT sponges show a 44.3% higher cooling efficiency than commercial Al cooling fins at a humidity of 50% due to the massive latent heat of water combining with the high thermal conductivity of CNTs and the high emissivity of the composites. The self-adjusting moisture absorption-desorption process could dissipate heat by water evaporation when electronics work at high power and spontaneously absorb moisture to regenerate the sponges at the standby mode of electronics. Besides, hard CNT sponges possess a much lower density (0.98-1.70 g cm^-3) than aluminum (2.7 g cm^-3). This high-performance cooler provides an alternative thermal management method for electronics.