Abstract: Provided in the present invention is a positive electrode for use in an Electric Double Layer (EDL) Hybrid Electrochemical Capacitor (HEC). Embodiments of the invention can be further adapted produce an EDL HEC with a high specific energy value and a high maximum voltage value. Some aspects of an embodiment of the present invention, including the aforementioned positive electrode, also cooperate to provide an EDL HEC that has a relatively high cycleability.

Abstract: A method of formation and charge of a negative polarizable electrode of an electric double layer capacitor. The method can be used for manufacturing of high capacitance capacitors utilizing the energy of the electric double layer. The methods achieve hydrogen evolution on carbonaceous materials using very negative potentials. The methods provide an EDL capacitor, employing an aqueous electrolyte, with improved specific energy. The methods may also ensure the hermeticity of the capacitor. The methods include pretreating the electric double layer capacitor by keeping the negative polarizable electrode at a desired minimum potential prior to use. Desirably, the minimum potential ranges from about −0.25 to about −1.2 V vs. a reference hydrogen electrode.