Electric double layer capacitor and method of fabricating the same

A method of fabricating an electric double layer capacitor comprising two metal cases each having a disc-shaped bottom wall and a cylindrical sidewall extending from the bottom wall;

• a polarizable electrode set in each of the metal cases and comprising a paste electrode material including an activated carbon powder, an electrolyte, a binder and a conductive additive;
• a separator made of a porous material and set between the polarizable electrodes of the two metal cases to function to conduct only ions therethrough;
• and a gasket having an electrical insulating property and set in the metal cases to function to prevent a short-circuit failure, the method comprising the following steps of:
• mixing the activated carbon powder with the electrolyte, the binder and the conductive additive, to prepare slurry of the activated carbon powder;
• pitting or etching any one face of a metal substrate made of the same material as the metal cases, to form a plurality of indentations on the face;
• coating the slurry of the activated carbon powder onto the indented face of the metal substrate, followed by drying the coated face;
• compressing the coated face by use of a heating roll at 100-250° C., thereby affording a polarizable electrode sheet;
• and
• cutting the polarizable electrode sheet into polarizable electrodes having shapes and sizes complementary to the metal cases, followed by welding the polarizable electrodes and the metal cases together after aligning the centers thereof with each other.