Electric double-layer capacitor and method for preparing the same

Abstract

An electric double-layer capacitor includes a cell structure formed by laminating basic cells in series one on another. Each of the basic cells includes a pair of collectors, a separator disposed between said collectors, gaskets disposed at peripheral edges of said pair of collectors and said separator to define a pair of closed spaces, and a pair of polarizable electrodes which are disposed in said closed spaces defined by said collectors, said separator and said gaskets, respectively and which contain an electrolytic solution. The basic cells are laminated one on another with a back of each of said collectors opposed to said polarizable electrode serving as a connection surface. The electric double-layer capacitor further includes a lead terminal/electrode plate assembly having electrode plates bonded to the collectors located at opposite ends of the cell structure through conductive bond layers. At least one of interfaces between the collectors included in said cell structure has a surface shape based on a rugged surface shape of the surface of the polarizable electrode contacting with and opposed to at least one of the two collectors forming such interface. Thus, in the electric double-layer capacitor, a lower ESR can be realized both at an initial stage of the service of the capacitor and after the service of the capacitor for a long period.