Extended life capacitor and method

Claim 2

An extended life capacitor comprising, in combination: an enclosing body having an interior surface formed from a material highly resistance to corrosion by the electrolyte of the capacitor; 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 high surface area carbon material impregnated with an electrolyte; 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 an hermetically sealed body and high purity components.

Claim 3

The extended life capacitor as set forth in claim 1, wherein said inhibiting means includes a body interior surface formed from tantalum or tantalum alloy.

Claim 4

The extended life capacitor as set forth in claim 1, wherein said inhibiting means inhibits the loss of electrolyte to less than 2% per year.

Claim 5

The extended life capacitor as set forth in claim 1, including means to limit the establishment of spurious capacitive means, by electrochemical action of the electrolyte at said cathode and anode, in series with said plurality of capacitor cells so that the total farad capacity decreases less than 2% per year.

Claim 6

The extended life capacitor as set forth in claim 4, wherein said limiting means includes a noble metal coating on at least part of the surface of the anode.

Claim 7

The extended life capacitor as set forth in claim 4, wherein said limiting means includes a noble metal coating on at least part of the surface of said cathode.

Claim 8

The extended life capacitor as set forth in claim 4, wherein said limiting means includes a gold coating on the surface of said anode.

Claim 9

The extended life capacitor of claim 7, wherein said limiting means further includes a gold coating on the surface of said cathode.

Claim 10

The extended life capacitor of claim 8, wherein the capacitor cells are conductive material with electrolyte therein containing about 36-40% by weight of sulfuric acid to water.

Claim 11

The extended life capacitor as set forth in claim 1, wherein said electrolyte is about 25-76% by weight of sulfuric acid to water.

Claim 12

The extended life capacitor as set forth in claim 1, wherein said electrolyte is about 36-40% by weight of sulfuric acid to water.

Claim 13

The extended life capacitor as set forth in claim 1, wherein said electrolyte is about 38% by weight of sulfuric acid to water.

Claim 14

The extended life capacitor as set forth in claim 1, wherein each of said capacitor cells includes a first and second electrode of activated carbon material impregnated with liquid electrolyte, and with a separator therebetween of a polysulfone material.

Claim 15

The extended life capacitor as set forth in claim 1, wherein said enclosing body is cylindrical and the inner surface of said cylindrical body is generally smooth.

Claim 16

The extended life capacitor as set forth in claim 14, wherein said smooth inner cylindrical surface is outside the electron conducting path of the entire capacitor.

Claim 17

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° C. to +125° C.

Claim 18

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° C. to +125° C.

Claim 19

The extended life capacitor as set forth in claim 16, wherein said electrode disposed inside said cap is a disc-shaped anode electrically connected to said lead-in.

Claim 20

The extended life capacitor as set forth in claim 16, including a conductive sponge between the closed end of said body and the respective end of said stack.

Claim 21

The extended life capacitor as set forth in claim 16, including means to limit the formation of a spurious capacitor element in series with said capacitor cells so that the total farad capacity decreases less than 2% per year.

Claim 24

The method of producing an extended life capacitor of claim 20, wherein at least a portion of the electrodes are coated with a noble metal prior to assembly.

Claim 25

The method of producing an extended life capacitor of claim 21, wherein the noble metal is gold.

Claim 26

The method of producing an extended life capacitor of claim 20, which further comprises the steps of inserting a conductive metal sponge cushion at the base prior to inserting a plurality of capacitor cells.

Claim 27

The method of producing an extended life capacitor of claim 23, wherein a conductive metal sponge cushion is inserted after the insertion of the capacitor cells and prior to attaching the cover.

Claim 28

The method of producing an extended life capacitor of claim 24, wherein the cover is welded to the tantalum can.

Claim 29

An extended life capacitor comprising in combination: a hollow body member formed from a material highly resistant to corrosion and having an open end and a closed end base with at least a portion of the inner surface of the closed end base having a coating of a noble metal to serve as an electrical contact region; a plurality of individual double layer capacitor cells stacked within said hollow body member; one end of said stacked double layer capacitor cells having electron conduction relation with said closed end base; a cap formed of material highly resistant to corrosion closing said open end of said hollow body member and hermetically sealed to said hollow body member; a conductive lead-in through said cap hermetically sealed thereto and insulated therefrom; an electrode within said hollow body member connected to said lead-in having an electrical contact portion thereof at least partially coated with a noble metal and having an electron conduction relation with the other end of said stacked double layer capacitor cells; and said double layer capacitor cells including activated carbon material and an electrolyte therein containing about 25-76 percent by weight sulfuric acid whereby the hermetic sealing, the purity of the components and the noble metal electrical contacts assure an extended service life.

Claim 30

An extended life capacitor comprising in combination: a hollow body member formed from a material highly resistant to corrosion and having an open end and a closed end base with at least a portion of the inner surface of the closed end base having a coating of a noble metal to serve as an electrical contact region; a plurality of individual double layer capacitor cells stacked within said hollow body member; one end of said stacked double layer capacitor cells having electron conduction relation with said closed end base; a cap formed of material highly resistant to corrosion closing said open end of said hollow body member and hermetically sealed to said hollow body member; a conductive lead-in through said cap hermetically sealed thereto and insulated therefrom; an electrode within said hollow body member connected to said lead-in having an electrical contact portion thereof at least partially coated with a noble metal and having an electron conduction relation with the other end of said stacked double layer capacitor cells; and said double layer capacitor cells including activated carbon material and an electrolyte therein containing about 25-76 percent by weight sulfuric acid whereby the hermetic sealing, the purity of the components and the noble metal electrical contacts assure an extended service life.

Claim 31

The extended life capacitor of claim 26 wherein a first conductive metal sponge is positioned between said closed end base and the adjacent end of said stacked double layer capacitor cells and a second conductive metal sponge is positioned between said contact portions of said electrode and said other end of said stacked double layer capacitor cells, the metal sponges so positioned for absorbing shock and high acceleration and deceleration focus.

Claim 32

The extended life capacitor of claim 27 wherein said noble metal is gold.