Abstract: An electric double-layer capacitor capable of maintaining a low leakage current over a long period of time even in a high temperature range, having high reliability in the high temperature range, and thereby making it possible to extend the life of an apparatus using the electric double-layer capacitor is provided. Further, a method for manufacturing such an electric double-layer capacitor is also provided. An electric double-layer capacitor and its manufacturing method are characterized in that an aqueous electrolytic solution containing a water-soluble electrolyte of which a Hammett acidity function H0 at a temperature of 25° C. is ?2.8 or higher and a vapor pressure at a temperature of 100° C. is 400 mmHg or lower is used.

Abstract: An electric double-layer capacitor capable of maintaining a low leakage current over a long period of time even in a high temperature range, having high reliability in the high temperature range, and thereby making it possible to extend the life of an apparatus using the electric double-layer capacitor is provided. Further, a method for manufacturing such an electric double-layer capacitor is also provided. An electric double-layer capacitor and its manufacturing method are characterized in that an aqueous electrolytic solution containing a water-soluble electrolyte of which a Hammett acidity function H0 at a temperature of 25° C. is ?2.8 or higher and a vapor pressure at a temperature of 100° C. is 400 mmHg or lower is used.

Abstract: An electric double-layer capacitor includes a capacitor element, which includes a positive electrode and a negative electrode that face each other in a predetermined direction; a positive plate-like terminal portion connected to one end of the capacitor element in the predetermined direction; a negative plate-like terminal portion connected to another end of the capacitor element in the predetermined direction; and an exterior body encapsulating the capacitor element, the positive plate-like terminal portion, and the negative plate-like terminal portion. The positive and the negative plate-like terminal portions include parts that face each other in the predetermined direction, and at least one protruding portion protrudes from a corresponding one of the parts toward a corner of the exterior body.

Abstract: An electric double-layer capacitor includes a capacitor element, which includes a positive electrode and a negative electrode that face each other in a predetermined direction; a positive plate-like terminal portion connected to one end of the capacitor element in the predetermined direction; a negative plate-like terminal portion connected to another end of the capacitor element in the predetermined direction; and an exterior body configured to encapsulate the capacitor element, the positive plate-like terminal portion, and the negative plate-like terminal portion. The positive and the negative plate-like terminal portions have parts that face each other in the predetermined direction, and at least one protruding portion that protrudes from any one of the parts.