NOVELTY - Preparation of active electrode material (210) involves providing activated carbon with a sulfur content not greater than 50 parts per million; providing binder; and mixing the activated carbon and the binder to obtain a mixture of active electrode material. The process further includes providing an additional additive component having a sulfur content not exceeding an amount so that the mixture of active electrode material has a sulfur content not greater than 50 parts per million.    USE - For preparation of active electrode material to obtain electrodes useful in electrochemical double layer capacitor (claimed) and in energy storage devices, primary (non-rechargeable) battery cells, secondary (rechargeable) battery cells, fuel cells and capacitors.    ADVANTAGE - The electrode comprising the active electrode material decreases current leakage of the capacitor. The electrodes comprising the active electrode material when immersed in electrolyte does not lower the breakdown voltage of electrolyte to the same extent as commercially known porous electrodes.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) an electrode comprising: a current collector (205); and a film of active electrode material attached to the current collector, where the activated carbon in the active electrode material has a sulfur content of 0 to about 50 ppm. The active electrode material includes conductive carbon particles; and    (2) an electrochemical double layer capacitor comprising: a first electrode containing a first current collector and a first film of active electrode material, where the first film comprises a first surface and a second surface and the first current collector is attached to the first surface of the first film; a second electrode containing a second current collector and a second film of active electrode material, where the second film comprises a third surface and a fourth surface, and the second current collector is attached to the third surface of the second film; a porous separator (220) disposed between the second surface of the first film and the fourth surface of the second film; a container; an electrolyte, where the first electrode, the second electrode, the porous separator, and the electrolyte are disposed in the container and the first film is at least partially immersed in the electrolyte and the second film is at least partially immersed in electrolyte and the porous separator is at least partially immersed in the electrolyte. Each of the first and second films include a mixture of carbon with a sulfur content not greater than 50 parts per million and binder.    DESCRIPTION OF DRAWING(S) - The figure shows cross-sectional view of electrode assemblies that are used in ultracapacitor.    Electrode assembly (200)    First current collector (205)    First active electrode film (210)    Porous separator (220)    Second active electrode film (230)    Second current collector. (235)