Supercapacitors With C and Nanostructured Mn0₂ Electrodes

A class of developmental asymmetric electrochemical capacitors is based on (1) nonpolarizing positive electrode made of nanotructured γ-MnO2, (2) aqueous electrolyte , and (3) polarizing negative electrodes made of activated carbon. Like other state-of-the-art electrochemical capacitors, these can store several hundred times as much energy per unit weight or volume as can traditional electrolytic capacitors. In comparison with other, symmetric state-of-the-art electrochemical capacitors, these asymmetric electrochemical capacitors are expected to be capable of higher energy densities. In addition, by virtue of the high surface areas of the nanostructured γ-MnO2 electrodes, these capacitors are expected to be capable of high power densities. These capacitors could be particularly useful as load-leveling devices in conjunction with batteries, or as replacements for batteries, in portable electronic devices that rely on short-term intermittent or pulsed high power.