Growth time performance dependence of vertically aligned carbon nanotube supercapacitors grown on aluminum substrates

Vertically aligned carbon nanotubes (VACNTs) present a uniform pore size as compared to activated carbon or nonaligned carbon nanotubes, increasing the available surface area for electric double layer formation. In this study, we fabricate VACNTs grown directly on thin aluminum foils using only conductive support layers in a scalable, low-pressure chemical vapor deposition (LPCVD) process. These highly flexible and conductive electrodes were optimized by utilizing combinations of diffusion barrier layers and catalyst support layers to alter the electrode porosity and available surface area. Specific capacitances for five growth times (5, 10, 15, 20 and 25 min) were measured to be 30-79 F g(-1) and compare favorably to similar studies. Power densities for all supercapacitor sheets exceeded 3 MW kg(-1) and consistently exceeded other VACNT supercapacitor studies. Our study demonstrates the benefits and applicability of fabricating VACNTs on metal substrates using scalable techniques for flexible and conductive supercapacitors. (C) 2012 Elsevier Ltd. All rights reserved.