Patent attributes
A hydrophobic film is formed on the electrode foil surface by adding a straight-chain saturated dicarboxylic acid represented by the general formula: HOOC(CH2)nCOOH (wherein n indicates an integer from 9 to 11) to the electrolytic solution for medium/high-voltage electrolytic capacitor. Addition of a large amount of water to the electrolytic solution is allowed since this hydrophobic film suppresses the hydration reaction between the electrode foil and water. Further, it is possible to retain good lifespan property of the electrolytic capacitor in a medium/high-voltage electrolytic solution by having low specific resistance property and by suppressing the hydration decomposition of the electrode foil, wherein the electrolytic solution is azelaic acid, sebacic acid, 1-methyl-azelaic acid, 1,6-decanedicarboxylic acid, or a salt thereof dissolved in a solvent having ethylene glycol as the main component.
