Remarkably enhanced thermal transport based on a flexible horizontally-aligned carbon nanotube array film

Abstract

It has been more than a decade since the thermal conductivity of vertically aligned carbon nanotube (VACNT) arrays was reported possible to exceed that of the best thermal greases or phase change materials by an order of magnitude. Despite tremendous prospects as a thermal interface material (TIM), results were discouraging for practical applications. The primary reason is the large thermal contact resistance between the CNT tips and the heat sink. Here we report a simultaneous sevenfold increase in in-plane thermal conductivity and a fourfold reduction in the thermal contact resistance at the flexible CNT-SiO2 coated heat sink interface by coupling the CNTs with orderly physical overlapping along the horizontal direction through an engineering approach (shear pressing). The removal of empty space rapidly increases the density of transport channels, and the replacement of the fine CNT tips with their cylindrical surface insures intimate contact at CNT-SiO2 interface. Our results suggest horizontally aligned CNT arrays exhibit remarkably enhanced in-plane thermal conductivity and reduced out-of-plane thermal conductivity and thermal contact resistance. This novel structure makes CNT film promising for applications in chip-level heat dissipation. Besides TIM, it also provides for a solution to anisotropic heat spreader which is significant for eliminating hot spots.

Thermal conductivity of carbon nanotube networks: a review

“…The third-harmonic method (3-x method) is commonly used in measurement of thermal properties of bulk materials and films [31][32][33][34][35][36][37][38][39], in which the sample is heated using alternating current with x frequency. A temperature variation with 2 x frequency was induced in the sample while heating, and a drop in voltage with 3 x frequency was recorded across the heater.…”

Allotrope carbon materials in thermal interface materials and fuel cell applications: A review

“…24 Therefore, CNT is outstanding among advanced materials to be implemented in the thermal application and energy storage. CNTs are electrically conducting tools, which are comparable to diamond and have involved in many applications such as TIMs, [25][26][27] batteries, 28-30 energy storage, [31][32][33] supercapacitor, 34 fuel cell, [35][36][37][38] and portable sensors. [17][18][19]21,22 The synthesis of CNT is already established few years ago and has attained large scale of production.…”

“…Fuel cell application is affected by the presence of various types of carbon allotropes, including CNTs, [14][15][16] CB, [17][18][19] graphene, 20 carbon nanocoils (CNCs), 21-23 mesoporous carbon (MC), 8,24,25 carbon cloth, 26 carbon nanofibers (CNFs), 27 fullerene, 28 activated carbon (AC), 28 and carbon xerogel/aerogel 29 ; fuel cell performance is significantly affected by their presence. Table 3 indicates the carbon material properties as followed.…”

3D interconnected macrostructure based on nano-scale pyroprotein units for energy storage

“…[1][2][3][4][5][6][7][8][9][10][11] This bulk carbon architecture can exhibit nanometer-scale properties such as expanded surface area, which allow for nanoelectronic and nanoionic interactions within the materials' internal spaces and facilitate rapid charge storage via a pseudocapacitive mechanism. 7,12,13 Surface-driven redox reactions occur predominantly on defective carbon structures such as intrinsic topological and edge defects, as well as extrinsic defects, [14][15][16][17][18] However, sp 3 carbon structures have poor electrical conductivities, which result in unfavorable kinetic properties.…”