An electric double-layer ultracapacitor configured to maintain desired operation at an operating voltage of three volts, where the capacitor includes a housing component, a first and a second current collector, a positive and a negative electrode electrically coupled to one of the first and second current collectors, a separator positioned between the positive and the negative electrode, and an electrolyte in ionic contact with the electrodes and the separator. At least one of the positive electrode and the negative electrode can be made of a carbon based layer having a mesoporosity and/or a microporosity optimized for ionic mobility therewithin.