Binder-free carbon nanotube-activated carbon composites for electrochemical applications

In this report a unique approach is developed to exploit the properties of carbon nanotubes (CNTs) in the fabrication of CNT-activated carbon composites for use in electrochemical applications. Here CNT networks are utilized as a matrix material to host micron sized activated carbon particles in the creation of porous carbon-carbon composites. Through the incorporation of activated carbon (aC) particles in a host CNT network, a highly conductive, large surface area porous carbon material is produced without the use of any polymeric binders. The high aspect ratio of CNTs allow for the creation of a conducting, flexible and free-standing material while the activated carbons introduce high surface areas with abundant microporous domains. The mesoporous domains between CNTs create a porous media through which gas or liquid phases can readily access the internal microstructure of the material. Surface area and electrical conductivity measurements were performed on samples with varied weight ratios of aC to CNTs. Samples of up to 50 wt.% aC have been achieved within a single-walled carbon nanotube matrix and greater than 65 wt.% aC in a matrix of multi-walled carbon nanotubes. It was found that the surface area of the samples follows the rule-of-mixtures as the ratio of aC to CNT is increased; indicating the composite's surface area can be tailored through choice of constituent materials. The resulting electrical conductivity of the composite was found to be a function of the achievable conductivity for pure CNT. Scanning electron microscopy revealed a uniform aC particle distribution with various aC-CNT interactions throughout the materials.