Specific Ion Effects on Double-Layer Capacitance of a C-Cloth Electrode Showing Extended Charge Acceptance

摘要

Much of the basic and developmental work on Electrochemical Supercapacitors [1] for charge storage and delivery has been directed to employment of the interfacial double-layer capacitance exhibited by high specific-area carbon materials, e.g. C powders, felts, woven cloth, C aerogels and C nanotubes based on Fullerene structures. A complementary area has been utilization of the so-called pseudocapacitance that is manifested at some redox-oxide surfaces, e.g. RuO{sub}2, IrO{sub}2, WO{sub}3, etc and at conducting polymers, e.g. polyaniline and polyfluorophenylthiophene derivatives [2]. With respect to electrochemical capacitors based on double-layer capacitance, the seminal work of Grahame [3] on the specificity of capacitance vs. potential profiles at Hg to the type of anion of the electrolyte clearly demonstrated major anion-specific effects on double-layer capacitance, especially at potentials positive to the potential of zero charge (pzc), with evidence that over such potential ranges densities of charge accommodation, μC cm{sup}(-2), were substantially increased, e.g. for Cl{sup}-, Br{sup}- adsorption.