Patent ID: 8765286

Claim:
An electrochemical device comprising: a casing having a recess with an opening; a lid connected to an open side of the casing so as to form an enclosed portion between the lid and the recess; and a rechargeable and dischargeable storage element enclosed in the enclosed portion, the storage element including a first electrode sheet, a second electrode sheet, and a porous separate sheet capable of maintaining an electrolytic solution, the separate sheet being interposed between the first and second electrode sheets, wherein the separate sheet includes: a first section interposed between the first and second electrode sheets, the first section in direct contact with the first and second electrode sheets, and having a first thickness; a second section having a second thickness greater than the first thickness, the second section extending outwardly with respect to the first and second electrode sheets without contacting the lid and having a porosity greater than that of the first section; and a third section disposed on at least a part of a surface of the second section, the third section contacting an outer surface of each of the first and second electrode sheets in such a manner as to supply the electrolytic solution to the first and second electrode sheets.