Electric double-layer capacitor and method for preparing the same

An electric double-layer capacitor comprising

• a basic cell including 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,
• a lead terminal/electrode plate assembly including electrode plates bonded to said basic cell through conductive bond layers, with at least one of backs of the collectors of the basic cell, which are opposed to the polarizable electrodes, serving as a connection surface;
• and
• the surface of at least one of said collectors forming an interface with said conductive bond layer has a surface shape based on the rugged surface shape of the polarizable electrode contacting with said collector.

A process for producing an electric double-layer capacitor, comprising the steps of

• (A) putting a collector on a flat plate and a frame-shaped gasket element having an opening into abutment against each other to define a recess with a bottom surface formed by said collector and sides formed by the inner sides of the opening in said gasket element,
• (B) disposing a polarizable electrode impregnated with an electrolytic solution,
• (C) placing two intermediate products fabricated through said steps (A) and (B) and a flat plate-shaped separator, so that end faces of said gasket elements forming the openings in said intermediate products are put into abutment against peripheral edges of thickness-wise opposite surfaces of said separator,
• (D) thermally fusing said two gasket elements included in an assembly resulting from said step (C) integrally to each other under a pressure lower than the atmospheric pressure and equal to or higher than 67 Pa to form a gasket, and covering a side of the separator with the gasket, thereby forming a basic cell including the two intermediate products and the separator integrally bonded to each other,
• (E) laminating a plurality of said basic cells formed in the above manner in series one on another, so that backs of the collectors included in each of the basic cells contacting with the polarizable electrodes are bonded surfaces, thereby forming a cell structure,
• (F) putting the two collectors forming opposite ends of the cell structure into abutment against electrode plates included in a lead terminal/electrode plate assembly through conductive bond layers, and
• (G) pressing the surface of a laminate fabricated at said step (F), which is in abutment against the collector, from outside said electrode plates included in said lead terminal/electrode plates.

A process for producing an electric double-layer capacitor, comprising the steps of

• (H) putting a collector on a flat plate and a frame-shaped gasket element having an opening into abutment against each other to define a recess with a bottom surface formed by said collector and sides formed by the inner sides of the opening in said gasket element,
• (I) disposing a polarizable electrode impregnated with an electrolytic solution,
• (J) placing two intermediate products fabricated through said steps (H) and (I) and a flat plate-shaped separator, so that end faces of said gasket elements forming the openings in said intermediate products are put into abutment against peripheral edges of thickness-wise opposite surfaces of said separator,
• (K) thermally fusing said two gasket elements included in an assembly resulting from said step (J) integrally to each other under a pressure lower than the atmospheric pressure and equal to or higher than 67 Pa to form a gasket, and covering a side of the separator with the gasket, thereby forming a basic cell including the two intermediate products and the separator integrally bonded to each other,
• (L) putting the two collector included in said basic cell and electrode plates included in a lead terminal/electrode plate assembly into abutment against each other through conductive bond layer, and
• (M) pressing a laminate formed at said step (L) from outside electrode plate included in the lead terminal/electrode assembly in a direction normal to the abutment surface of said collector.