Conductive electrolyte for high voltage capacitors

Abstract

The present invention is directed to a conductive electrolyte for use in high voltage electrolytic capacitors and to an electrolytic capacitor impregnated with the electrolyte of the present invention for use in an implantable cardioverter defibrillator (ICD). The electrolyte according to the present invention is composed of a two solvent mixture of ethylene glycol and a polar organic cosolvent from the group of 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, hexyl alcohol, or di(ethylene glycol). Dissolved in this mixture is a combination of boric acid with either an aliphatic dicarboxylic acid of carbon chain length from eight to thirteen (C8 to C13) or a very long chain dicarboxylic acid, where the acid functional groups are separated by 34 carbons (referred to as “dimer acid”). The solution is then neutralized with an amine. A cathode depolarizer, or degassing agent, from the group of nitro-substituted aromatic compounds (nitroaromatics) can be added to reduce the amount of gas produced during capacitor life. Hypophosphorous acid and/or a colloidal suspension of silica in ethylene glycol may be added to enhance the life characteristics of the electrolyte, resulting in lower leakage currents and better voltage droop characteristics. The water content may be adjusted with deionized water to achieve a Karl Fischer titration (water content) measurement of 1.0-8.0% to achieve proper age characteristics.

Dependencies are inferred from the claim text.