An ultracapacitor that contains at least one electrochemical cell is provided. The cell includes a first electrode that contains a first carbonaceous coating (e.g., activated carbon particles) electrically coupled to a first current collector, a second electrode that contains a second carbonaceous coating (e.g., activated carbon particles) electrically coupled to a second current collector, an aqueous electrolyte in ionic contact with the first electrode and the second electrode and that contains a polyprotic acid (e.g., sulfuric acid), and a separator that is positioned between the first and second electrodes. Through selective control over the particular nature of the materials used to form the ultracapacitor, as well as the manner in which they are formed, a variety of beneficial properties may be achieved.