The development of materials for carbon double-layer supercapacitors

The electrochemical properties of porous carbon electrodes were tested by both cyclic voltammetry and impedance spectroscopy. By varying the type/amount of binder (Nafion, Teflon, sol-gel) different capacitance values and mass loadings were observed. As these electrodes were being developed for supercapacitor applications, the mass loading is important (i.e. mass a energy). Also the resistances associated with these electrodes were greatly reduced by a new cell design that almost eliminated the solution resistance. Different forms of carbon were tested including both powders and a fabric variety; the fabric electrodes exhibited a higher surface area, as well as much more mechanical stability. In the carbon powder work, it was found that the carbon Black Pearls 2000 was best for the specific capacitance (321 F/g) and it was optimized (higher specific capacitance, lower resistance) by the addition of 1% Nafion, while the total capacitance was optimized by a combination of 5% Teflon and 5% Nafion