CORROSION RESISTANT FEEDTHROUGH

Abstract: Use of Titanium and Titanium alloys (14) in combination with and CABAL-12 glass (12) for improved corrosion resistant feedthroughs.

Description: CORROSION RESISTANT FEEDTHROUGH Background of the Invention Glass seals are used in various arrangements including batteries and other electrochemical cells . For example, in battery headers, glass seals are used to seal the battery container while allowing one or more electrical terminals to extend through the seal for interior/exterior connection thereto . The term "feedthrough" shall be used herein to describe such arrangements in generic fashion. In batteries and the electrochemical cells , corrosion has been encountered. For example, batteries which include various organic electrolyte systems give rise to corrosion and cracking of glass and metal feedthrough components. A special glass composition has developed by Sandia National Laboratories which exhibit improved corrosion resistance. It is generally referred to as CABAL-12 glass. Although this glass has desirable corrosion resistance and resistance to cracking, it has been difficult to find metals which will reliably wet the glass to form strong, hermetic seals with it and which work well with respect to the other aspects of seal forming such as weldability, expansion characteristics and so forth. The ' general purpose of this invention is to provide a combination of metal and CABAL-12 GLASS for improved feedthrough structures in battery and electrochemical cell applications. Summary of the Invention This invention relates to feedthrough structures which utilize CABAL-12 glass particularly for use in aggressive battery organic electrolyte environments e.g., a lithium thionyl chloride cell or cells of other active chemistries such as Mn0 2 , and CFX, for example. It has been discovered that this glass has a unique affinity for sealing to titanium and titanium alloys. In its preferred embodiment the invention relates specifically to hermetic, corrosion resistant, compression-type sealed feedthroughs utilizing single or multiple terminals or pins of niobium, tantalum, molybdenum and titanium or alloy thereof, contained within a header or sleeve of titanium or a titanium alloy, Titanium-6A1-4V being preferred. Brief Description of the Drawing Fig. 1 is a schematic cross-section of a battery header in accordance with the invention, and Fig. 2 is a schematic cross-section of a feedthrough with sleeve according to the invention combined with a metal container for use as an electrochemical cell. Description of the Preferred Embodiments While this invention may be embodied in many different forms, there are shown in the drawings and described in detail herein specific preferred embodiments of the invention. The present disclosure is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiments illustrated. Referring to Fig. 1, a header of typical construction is shown which includes a center pin or terminal 10, a glass seal member 12 and an outer member 14. This arrangement and that of Fig. 2 are typical feedthrough seal arrangements which may make use of the invention. Other arrangements may be used as well and may take any configuration in which the metal is wetted by the glass. Referring now to the Fig. 2 the invention in a preferred form includes a terminal 10 extending through a glass seal 12 which is received into a sleeve or header 14. Sleeve 14 may be welded into an opening in a battery container 16 of, for example, stainless steel. The assembly, requiring forming weights, is placed in an oven or furnace and heated causing the glass to wet the metallic components forming a he_rmetic seal between the glass and the metal components. Such a feedthrough may thereafter be welded if necessary, into any desirable container or the like. In its preferred form, terminal 10 consists essentially of niobium, or titanium or an alloy thereof. Sleeve 14 is of titanium or a titanium alloy Ti-6A1-4V The glass 12 is CABAL-12, which is of the following composition: The combination of materials described forms a compression seal which is hermetic and corrosion resistant. This completes the description of the preferred and alternate embodiments of the invention. Those skilled in the art may recognize other equivalents to the specific embodiments described herein, which equivalents are intended to be encompassed by the claims attached hereto. Having described the invention, the exclusive rights and privileges thereto are to be defined by the forego ing claims in the l ight of the f oregoing description.

Claims: WHAT IS CLAIMED IS: 1. An electrical feedthrough comprising an electrical terminal selected from the group consisting of niobium, tantalum molybdenum, Titanium, titanium alloys, or alloys of any of the foregoing, a glass insulator of the CABAL-12 composition Type positioned around a portion of the terminal and in sealing engagement therewith and a sleeve or header comprised of a titanium or a titanium alloy positioned around a portion of the glass insulator for receiving same in sealing engagement therewith. 2. The feedthrough of Claim 1 in which the sleeve or header titanium alloy is Ti-6A1-4V. 3. A glass/metal feedthrough seal of the compression type including an electrical terminal selected from the group consisting of niobium, tantalum, molybdenum, titanium, titanium alloys or alloys of any of the foregoing; a glass insulator of the CABAL-12 composition type positioned around a portion of the terminal and in sealing engagement therewith and a sleeve or header consisting essentially of titanium or a titanium alloy positioned around a portion of the glass insulator for receiving same in sealing engagement therewith. 4. The feedthrough of Claim 3 in which the titanium alloy is Ti-6A1-4V. 5. An electrochemical cell of the type including corrosive contents in a container and wherein the container includes an opening carrying an electrical terminal which extends from the exterior of the cell through the opening and into the interior thereof; a feedthrough assembly positioned in the opening and around the terminal, the assembly comprising; a sleeve or header attached to the container, the sleeve or header consisting essentially of titanium or a titanium alloy 1 and a glass seal carried by the sleeve or header and 2 surrounding the terminal in sealing engagement therewith, 3 the glass being of the CABAL-12 composition type. 4 6. The cell of Claim 5 in which the feedthrough 5 seal is hermetic and of the compression type by virtue of 6 including a terminal of niobium, tantalum, molybdenum, 7 titanium, a titanium alloy or any alloy or any of the 8 foregoing. 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 -24 25 26 27 28 29 30 31 32 33 34 35 36

Inventors: LESSAR JOSEPH FRANCIS, TAYLOR WILLIAM JOHN, LESSAR, JOSEPH, FRANCIS, TAYLOR, WILLIAM, JOHN
Applicants: MEDTRONIC INC, MEDTRONIC, INC.
Application year: 1990
Main classification: H01M2
IPC codes: C03C8, C03C29, H01M2, H01M6