Extended life capacitor and method

DETAILED DESCRIPTION Accordingly, the problem to be solved is how to construct a capacitor of high farad capacity in a small unit volume, and yet one with an extended life which resists corrosion, resists increased equivalent series resistance, and resists electrolyte loss.
The problem is substantially solved by this invention, which includes an extended life capacitor comprising, in combination, an enclosing body, a plurality of double layer capacitor cells inside said enclosing body and having first and second electron-conducting end members, said plurality of capacitor cells including a conductive material with an electrolyte therein, means providing electrical connection external to said body, mutually insulated, to said first and second end members of said plurality of capacitor cells as anode and cathode, means to inhibit the loss of electrolyte from the interior to the exterior of said capacitor body and said inhibiting means including a body the interior surface of which is formed from a material highly resistant to corrosion by said electrolyte.
One embodiment of this invention includes an extended life capacitor comprising, in combination, a hollow body having an inner peripheral surface of tantalum and having an open end and a closed end base with at least a portion of an inner surface of a noble metal, a cap cooperable with the open end of said body and having an inner surface of tantalum, a lead-in through said cap and hermetically sealed thereto in an insulated manner, an electrode insulated from and disposed inside said cap and connected to said lead-in, a plurality of individual capacitor cells in a stack inside said body, said electrode having at least a portion of a face of a noble metal in electron conduction with one end of said stack, the other end of said stack being in electron conduction with said closed end base, a welded connection between said cap and said body to establish a hermetically sealed capacitor, and said capacitor cells including conductive material with electrolyte therein containing about 36-40% by weight sulfuric acid whereby the hermetic sealing and high purity of the components plus the noble metal assure a service life in excess of 10 years at a temperature range of -55