Co-Axial Glass-To-Metal Seal Feedthrough For A Case-Neutral Electrochemical Cell

Abstract

A case-neutral electrochemical cell has an electrode assembly comprising a separator positioned between an anode and a cathode housed inside a casing. The casing supports a co-axial glass-to-metal seal comprising an inner insulating glass hermetically sealed to a terminal pin and to the inner surface of a first or inner ferrule. An outer insulating glass is hermetically sealed to the outer surface of the inner ferrule and the inner surface of a second or outer ferrule, and the outer ferrule is secured to an opening in the casing. Then, one of the anode and the cathode is connected to the terminal pin and the other of the anode and the cathode is connected to the first or inner ferrule. An electrolyte is provided in the casing to activate the electrode assembly.

Claims

1. A case-neutral electrochemical cell, comprising: a) a casing comprising an open-ended container closed by a lid; b) an electrode assembly housed inside the casing, the electrode assembly comprising an anode and a cathode separated from direct physical contact with each other by an intermediate separator; c) a co-axial glass-to-metal seal, comprising: i) a terminal pin; ii) an inner ferrule comprising an inner ferrule sidewall extending to an inner ferrule inside end residing inside the casing spaced from an inner ferrule outside end residing outside of the casing, wherein the inner ferrule inside and outside ends extend to an inner ferrule inner annular surface defining an inner ferrule opening opposite an inner ferrule outer annular surface; iii) an inner insulating glass residing in the inner ferrule opening and hermetically sealed to the terminal pin and the inner annular surface of the inner ferrule; iv) an outer ferrule comprising an outer ferrule sidewall extending to an outer ferrule inside end residing inside the casing spaced from an outer ferrule outside end residing outside of the casing, wherein the outer ferrule inside and outside ends extend to an outer ferrule inner annular surface defining an outer ferrule opening opposite an outer ferrule outer annular surface; and v) an outer insulating glass residing in the outer ferrule opening and hermetically sealed to the outer annular surface of the inner ferrule and the inner annular surface of the outer ferrule, vi) wherein the outer annular surface of the outer ferrule is secured to an opening in the casing, and vii) wherein one of the anode and the cathode is electrically connected to the terminal pin and the other of the anode and the cathode is electrically connected to the inner ferrule; and c) an electrolyte provided in the casing to activate the electrode assembly.

2. The case-neutral electrochemical cell of claim 1, wherein the inner insulating glass has a first glass softening temperature that is substantially equal to a second glass softening temperature of the outer insulating glass.

3. The case-neutral electrochemical cell of claim 1, wherein the inner and outer sealing glasses are TA-23 having a softening temperature about 862? C.

4. The case-neutral electrochemical cell of claim 3, wherein the TA-23 sealing glass has a working temperature that ranges from about 1,000? C. to about 1,100? C. and a working range temperature interval from about 175? C. to about 275? C.

5. The case-neutral electrochemical cell of claim 3, wherein the TA-23 sealing glass has a maximum heat treatment temperature that ranges from about 900? C. to about 950? C.

6. The case-neutral electrochemical cell of claim 1, wherein the inner and outer sealing glasses are Cabal-12 having a softening temperature about 726? C.

7. The case-neutral electrochemical cell of claim 6, wherein the Cabal-12 sealing glass has a working temperature that ranges from about 775? C. to about 825? C. and a working range temperature interval from about 50? C. to about a 135? C.

8. The case-neutral electrochemical cell of claim 6, wherein the Cabal-12 sealing glass has a maximum heat treatment temperature that ranges from about 750? C. to about 770? C.

9. The case-neutral electrochemical cell of claim 1 of either a primary or a secondary chemistry.

10. The case-neutral electrochemical cell of claim 1 of a primary chemistry having the anode of an alkali metal and the cathode of a cathode active material selected from a carbonaceous material, a fluorinated carbon, a metal, a metal oxide, a mixed metal oxide, a metal sulfide, and mixtures thereof.

11. The case-neutral electrochemical cell of claim 1 of a secondary chemistry having the anode of carbon or graphite and the cathode of a cathode active material selected from LiNiO.sub.2, LiMn.sub.2O.sub.4, LiCoO.sub.2, LiCO.sub.0.92SnO.sub.0.08O.sub.2 and LiCo.sub.1-xNi.sub.xO.sub.2.

12. The case-neutral electrochemical cell of claim 1, wherein the casing is selected from titanium, stainless steel, mild steel, nickel-plated mild steel, and aluminum.

13. The case-neutral electrochemical cell of claim 1, wherein the inside ends of the inner and outer ferrules residing inside the casing are substantially aligned along a plane.

14. The case-neutral electrochemical cell of claim 1, wherein the inside end of the inner ferrule extends further into the casing than the inside end of the outer ferrule.

15. A co-axial glass-to-metal seal (GTMS), comprising: a) a terminal pin; b) an inner ferrule comprising an inner ferrule sidewall extending to an inner ferrule inside end residing inside the casing spaced from an inner ferrule outside end residing outside of the casing, wherein the inner ferrule inside and outside ends extend to an inner ferrule inner annular surface defining an inner ferrule opening opposite an inner ferrule outer annular surface; c) an inner insulating glass residing in the inner ferrule opening and hermetically sealed to the terminal pin and the inner annular surface of the inner ferrule; d) an outer ferrule comprising an outer ferrule sidewall extending to an outer ferrule inside end residing inside the casing spaced from an outer ferrule outside end residing outside of the casing, wherein the outer ferrule inside and outside ends extend to an outer ferrule inner annular surface defining an outer ferrule opening opposite an outer ferrule outer annular surface; and e) an outer insulating glass residing in the outer ferrule opening and hermetically sealed to the outer annular surface of the inner ferrule and the inner annular surface of the outer ferrule.

16. The GTMS of claim 15, wherein the inner insulating glass has a first glass softening temperature that is substantially equal to a second glass softening temperature of the outer insulating glass.

17. The GTMS of claim 15, wherein the inner and outer sealing glasses are TA-23 having a softening temperature of about 862? C.

18. The GTMS of claim 15, wherein the inner and outer sealing glasses are Cabal-12 having a softening temperature of about 726? C.

19. A method for making a co-axial glass-to-metal seal (GTMS), comprising the steps of: a) providing a terminal pin; b) providing an inner ferrule comprising an inner ferrule sidewall extending to an inner ferrule inside end spaced from an inner ferrule outside end, wherein the inner ferrule inside and outside ends extend to an inner ferrule inner annular surface defining an inner ferrule opening opposite an inner ferrule outer annular surface; c) providing a sleeve-shaped inner insulating glass extending to an inner glass inside end spaced from an inner glass outside end, wherein the inner glass inside and outside ends extend to an inner glass inner annular surface defining an inner ferrule opening opposite an inner glass outer annular surface; d) providing an outer ferrule comprising an outer ferrule sidewall extending to an outer ferrule inside end spaced from an outer ferrule outside end, wherein the outer ferrule inside and outside ends extend to an outer ferrule inner annular surface defining an outer ferrule opening opposite an outer ferrule outer annular surface; and e) providing a sleeve-shaped outer insulating glass having an outer glass opening extending to an outer glass inside end spaced from an outer glass outside end, wherein the outer glass inside and outside ends extend to an outer glass inner annular surface defining an outer ferrule opening opposite an outer glass outer annular surface; f) positioning the terminal pin in the inner glass opening, positioning the inner insulating glass in the inner ferrule opening, positioning the inner ferrule in the outer glass opening, and positioning the outer glass in the outer ferrule opening to thereby provide a co-axial GTMS assembly; and f) subjecting the co-axial GTMS assembly to a heat treatment to hermetically seal the inner insulating glass to the terminal pin and the inner annular surface of the inner ferrule and to hermetically seal the outer insulating glass to the outer annular surface of the inner ferrule and the inner annular surface of the outer ferrule to provide the co-axial GTMS.

20. The method of claim 19, including providing the inner and outer sealing glasses being the same and selecting them from TA-23, Cabal-12, and Schott 8245.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG. 1 is a cross-sectional view of an exemplary case-neutral electrochemical cell 10 including a co-axial glass-to-metal seal (GTMS) 12 according to the present invention.

[0015] FIG. 1A is a cross-sectional view of another exemplary case-neutral electrochemical cell 10A including an alternate embodiment of a co-axial GTMS 12A according to the present invention.

[0016] FIG. 2 is a cross-sectional view of the co-axial GTMS 12 shown in the case-neutral electrochemical cell 10 of FIG. 1.

[0017] FIG. 3 is a perspective view of the co-axial GTMS 12 shown in FIGS. 1 and 2.

[0018] FIG. 4 is a side elevational view of the co-axial GTMS 12 shown in FIGS. 1 to 3.

[0019] FIG. 5 is a plan view of the co-axial GTMS 12 shown in FIGS. 1 to 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The term glass softening temperature is the minimum temperature at which a glass begins to deform under its own weight. As defined herein, the glass softening temperature is the temperature at which a glass fiber having a diameter ranging from 0.55 mm to 0.75 mm and a length of 23.5 cm elongates under its own weight at a rate of 1 mm/min.

[0021] The term glass working temperature is herein defined as the temperature at which a glass has a viscosity of about 104 poise. (For support, see Fundamentals of Inorganic Glasses, Arun K. Varshneya, 1994 p. 189.)

[0022] The glass softening temperature is generally at a lower temperature than the glass working temperature. The temperature interval between the glass softening point and the glass working point is herein defined as the glass working range.

[0023] The term viscosity is herein defined as the resistance to flow in a fluid or semi-fluid.

[0024] The term heat treatment or heating profile is herein defined as the application of heat starting at room temperature and increasing in a controlled manner to a maximum heating temperature and then decreasing the application of heat in a controlled manner back to room temperature. The heat treatment or heating profile may comprise a plurality of different heating or cooling rates as well as a plurality of temperature plateaus at which a temperature is held constant for a period of time.

[0025] Turning now to the drawings, FIGS. 1 and 1A illustrate two exemplary case-neutral electrochemical cells 10 and 10A according to the present invention. The exemplary nature of the cells 10, 10A is intended to provide context to the respective co-axial GTMSs 12 and 12A of the present invention. The exemplary case-neutral electrochemical cells 10, 10A comprise an open-ended container 14 closed by a lid 16. The container 14 has an annular sidewall 18 extending upwardly from a bottom wall 20 to an annular upper edge 22. The lid 16 is a plate-shaped member extending to an annular edge 24. The edge 24 of the lid 16 is welded to the upper edge 22 of the container 14 to close the container and provide a casing 26 for the electrochemical cells 10, 10A.

[0026] In the illustrated exemplary electrochemical cells 10, 10A, the electrode assembly comprises two spaced-apart first electrodes 28 and 30 that are positioned on opposite sides of a second, opposite polarity electrode 32. The first electrodes 28, 30 are housed in respective separator envelopes 34 and 36, and the second electrode 32 is housed in its own separator envelope 38.

[0027] In one embodiment of the electrode assembly, the first electrodes 28, 30 are anodes comprising anode active material supported on respective anode current collectors 40 and 42, and the second electrode 32 is a cathode comprising cathode active material supported on a cathode current collector 44. In another embodiment, the first electrodes 28, 30 are cathodes comprising cathode active material supported on respective cathode current collectors 40, 42, and the second electrode is an anode comprising anode active material supported on an anode current collector 44.

[0028] With respect to the first embodiment of the electrode assembly, the right anode 28 is comprised of opposed plates 28A and 28B of anode active material that are contacted to an intermediate anode current collector 40. A tab 40A extends upwardly from the right anode current collector 40. Similarly, the left anode 30 is comprised of opposed plates 30A and 30B of anode active material that are contacted to an intermediate anode current collector 42. A tab 42A extends upwardly from the left anode current collector 42. The cathode 32 is comprised of opposed plates 32A and 32B of cathode active material that are contacted to the opposite major sides of an intermediate cathode current collector 44. A tab 44A extends upwardly from the cathode current collector 44.

[0029] In the second embodiment of the electrode assembly, the right cathode 28 is comprised of opposed plates 28A and 28B of cathode active material that are contacted to an intermediate cathode current collector 40. A tab 40A extends upwardly from the right cathode current collector 40. Similarly, the left cathode 30 is comprised of opposed plates 30A and 30B of cathode active material that are contacted to an intermediate cathode current collector 42. A tab 42A extends upwardly from the left cathode current collector 42. The anode 32 is comprised of opposed plates 32A and 32B of anode active material that are contacted to the opposite major sides of an intermediate anode current collector 44. A tab 44A extends upwardly from the anode current collector 44.

[0030] FIGS. 2 to 5 show an exemplary embodiment of the co-axial glass-to-metal seal 12 according to the present invention incorporated into the case-neutral electrochemical cell 10 shown in FIG. 1. As particularly shown in FIG. 2, the exemplary co-axial GTMS 12 comprises a terminal pin 46 supported by an inner sleeve-shaped sealing glass 48 which is supported by an inner ferrule 50. The inner ferrule 50 is supported by an outer sleeve-shaped sealing glass 52 which is supported by an outer ferrule 54. The outer ferrule 54 is welded into an opening in the cell casing, such as in an opening in the lid 16 or in an opening in the casing container 18.

[0031] The first sleeve-shaped sealing glass 48 extends from an inner meniscus end 48A to an outer meniscus end 48B. The inner and outer ends 48A, 48B in turn extend to an outer annular surface 48C spaced from an inner annular surface 48D of the first glass sleeve 48. The inner annular surface 48D defines a cylindrically-shaped opening 56.

[0032] The terminal pin 46 is positioned in the cylindrically-shaped opening 56 of the first sleeve-shaped sealing glass 48. The terminal pin 46 is a rod-shaped member having an annular sidewall 46A that extends from a proximal end 46B to a distal end 46D. When the co-axial GTMSs 10, 10A of the present invention are built into the case-neutral electrochemical cells 10, 10A (FIGS. 1 and 1A), the proximal pin end 46B extends into the interior of the casing 26 and the distal pin end 46C resides outside the casing to provide for connection to a load which the cell 10 is intended to power.

[0033] The inner ferrule 50 is a sleeve-shaped member having an annular sidewall that extends from an inner end 50A to an outer end 50B. The inner and outer ends 50A, 50B in turn extend to an outer annular surface 50C spaced from an inner annular surface 50D.

[0034] The outer sleeve-shaped sealing glass 52 resides outwardly from the inner sealing glass 48 and is a sleeve-shaped member having an annular sidewall that extends from an inner meniscus end 52A to an outer meniscus end 52B. The inner and outer ends 52A, 52B in turn extend to an inner annular surface 52C spaced from an outer annular surface 52D. The inner annular surface 52D defines a cylindrically-shaped opening 58.

[0035] The outer ferrule 54 is a sleeve-shaped member having an annular sidewall that resides outwardly from the inner ferrule 50. The outer ferrule 54 has an annular sidewall that extends from an inner end 54A to an outer end 54B. The inner and outer ends 54A, 54B in turn extend to an outer annular surface 54C spaced from an inner annular surface 54D. An annular protrusion 54E extending outwardly from the outer annular surface 54C is spaced from the inner and outer ends 54A, 54B.

[0036] With the terminal pin 46 positioned in the cylindrically-shaped opening 56 of the inner sleeve-shaped sealing glass 48, the inner annular surface 48D of the inner sealing glass 48 contacts the annular sidewall 46A of the terminal pin 46 and the inner annular surface 50D of the inner ferrule 50 contacts the outer annular surface 48C of the inner sealing glass 48.

[0037] The inner ferrule 50 supporting the inner sealing glass 48 and the terminal pin 46 is sized to fit into the cylindrically-shaped opening 58 provided by the outer sealing glass 52. In this position, the outer annular surface 50C of the inner ferrule 50 contacts the inner annular surface 52C of the outer sealing glass 52 and the outer annular surface 52D of the outer sealing glass 52 contacts the inner annular surface 54D of the outer ferrule 54.

[0038] This assembly is then subjected to a heating protocol to simultaneously melt the inner and outer sealing glasses 48 and 52. The heating protocol causes the inner sealing glass 48 to flow into intimate sealing contact with the terminal pin 46 and the inner surface 50D of the inner ferrule 50 as the outer sealing glass 52 flows into intimate sealing contact with the outer surface 50C of the inner ferrule 50 and the inner surface 54D of the outer ferrule 54. When the molten inner and outer sealing glasses 48 and 52 cool, the inner sealing glass 48 hermetically seals to the terminal pin 46 and the inner annular surface 50D of the inner ferrule 50 and the outer sealing glass 52 hermetically seals to the outer annular surface 50C of the inner ferrule 50 and the inner annular surface 54D of the outer ferrule 54. This forms the co-axial GTMS 12 for use in the case-neutral electrochemical cell 10 according to the present invention.

[0039] In one preferred embodiment, the inner and outer insulating glasses 48 and 52 comprise TA-23, which is an alkaline earth aluminosilicate type glass developed by Sandia National Labs. TA-23 has a softening temperature of about 862? C., a working temperature that ranges from about 1,000? C. to about 1,100? C., and a working range temperature interval from about 175? C. to about 275? C. This means that one preferred embodiment of a heat treatment using TA-23 ranges from about 900? C. to about 950? C.

[0040] In another preferred embodiment, the inner and outer insulating glasses 48 and 52 are Cabal-12, which is a calcium-boro-aluminate type glass that was also developed by Sandia National Labs. Cabal-12 has a softening temperature of about 726? C., a working temperature that ranges from about 775? C. to about 825? C., and a working range temperature interval from about 50? C. to about a 135? C. This means that one preferred embodiment of a heat treatment using TA-23 ranges from about 750? C. to about 770? C.

[0041] In still another preferred embodiment, the inner and outer insulating glasses 48 and 52 are Schott 8245, which has a softening temperature of about 680? C.

[0042] Preferably, the softening temperatures of the inner and outer insulating glasses 48 and 52 for the co-axial GTMSs 12, 12A of the preset invention are substantially equal.

[0043] Further, the terminal pin 46 is preferably composed of an electrically conductive material, for example, MP35N, stainless steel, titanium alloy, platinum, platinum alloys, palladium, palladium alloys or a refractory metal such as molybdenum. The casing 26 comprising the open-ended container 18 closed by the lid 16 is preferably composed of a metallic material including stainless steel, such as 304L SS or a titanium alloy, mild steel, nickel-plated mild steel, and aluminum. Preferred materials for the inner and outer ferrules 50 and 54 include titanium, stainless steel, mild steel, nickel-plated mild steel, and aluminum.

[0044] The co-axial GTMS 12 is then hermetically secured to the casing 26. This is done by welding the outer ferrule 54 in a suitably sized opening in the lid 16. The annular protrusion 54E extending outwardly from the outer annular surface 54C of the outer ferrule 54 helps ensure that the upper ends 50B and 52B of the respective inner and outer ferrules 50 and 54 are substantially flush with the upper surface of the lid 16. In the exemplary electrochemical cell 10 shown in FIG. 1, the inner ends 50A and 54A of the respective inner and outer ferrule 50, 54 extend into the interior of the casing and are aligned along a common plane.

[0045] With the exception of the co-axial GTMS 12A, the exemplary case-neutral electrochemical cell 10A shown in FIG. 1A is constructed in a similar manner as the just described electrochemical cell 10 shown in FIG. 1. In the exemplary electrochemical cell 10A shown in FIG. 1A, however, the inner end 54A of the inner ferrule 50 extends a greater distance into the interior of the casing 26 than the inner surface 54A of the outer ferrule. This is a significant distinction because the extending inner ferrule 50 makes it easier to connect the current collector tabs 40A and 42A to the inner ferrule 50 than in the GTMS 10 shown in FIG. 1.

[0046] Once the co-axial GTMS 12 is created and the outer ferrule 54 is welded into an opening 16A in the lid 16, the proximal end 46B of the terminal pin 46 is electrically connected to either the anode or the cathode housed inside the cell casing 26 and the other of the anode and the cathode is electrically connected to the inner ferrule 50 (FIGS. 1 and 1A).

[0047] After the terminal pin 46 and the inner ferrule 50 are electrically connected to their respective electrode, the lid 16 is hermetically secured to the annular edge 22 at the open end of the container 18. The lid 16 may be hermetically sealed to the casing container 18 through such joining means as laser welding, resistance welding, ultrasonic welding, magnetic force welding, arc welding, soldering, and the like. An activating electrolyte (not shown) is then filled into the casing 26 through an electrolyte fill port or fill opening (not shown) in the lid 16.

[0048] In one embodiment, the electrochemical cells 10 and 10A are secondary or rechargeable cells. In a secondary system, the anode comprises a material capable of intercalating and de-intercalating the alkali metal, and preferably lithium. A carbonaceous anode comprising any of the various forms of carbon (e.g., coke, graphite, acetylene black, carbon black, glassy carbon, etc.), which are capable of reversibly retaining the lithium species, is preferred. Graphite is particularly preferred due to its relatively high lithium-retention capacity. Regardless of the form of the carbon, fibers of the carbonaceous material are particularly advantageous because they have excellent mechanical properties that permit them to be fabricated into rigid electrodes capable of withstanding degradation during repeated charge/discharge cycling.

[0049] The cathode of a secondary cell preferably comprises a lithiated material that is stable in air and readily handed. Examples of such air-stable lithiated cathode materials include oxides, sulfides, selenides, and tellurides of such metals as vanadium, titanium, chromium, copper, molybdenum, niobium, iron, nickel, cobalt, and manganese. The more preferred oxides include LiNiO.sub.2, LiMn.sub.2O.sub.4, LiCoO.sub.2, LiCO.sub.0.92Sn.sub.0.08O.sub.2 and LiCo.sub.1-xNi.sub.xO.sub.2.

[0050] The lithiated active material is preferably mixed with a conductive additive selected from acetylene black, carbon black, graphite, and powdered metals of nickel, aluminum, titanium, and stainless steel. The cathode further comprises a fluoro-resin binder, preferably in a powder form, such as PTFE, PVDF, ETFE, polyamides and polyimides, and mixtures thereof. The current collector is selected from stainless steel, titanium, tantalum, platinum, gold, aluminum, cobalt nickel alloys, highly alloyed ferritic stainless steel containing molybdenum and chromium, and nickel-, chromium- and molybdenum-containing alloys.

[0051] Suitable nonaqueous electrolytes for a secondary electrochemical systems comprise an inorganic salt dissolved in a nonaqueous solvent and, more preferably, a lithium metal salt dissolved in a quaternary mixture of organic carbonate solvents comprising a dialkyl (non-cyclic) carbonate selected from dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethyl methyl carbonate (EMC), methyl propyl carbonate (MPC) and ethyl propyl carbonate (EPC), and mixtures thereof, and at least one cyclic carbonate selected from propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC) and vinylene carbonate (VC), and mixtures thereof. Organic carbonates are generally used in the electrolyte solvent system for such battery chemistries because they exhibit high oxidative stability toward cathode materials and good kinetic stability toward anode materials.

[0052] In another embodiment, the electrochemical cells 10 and 10A are primary cells. A primary electrochemical cell that possesses sufficient energy density and discharge capacity for the rigorous requirements of implantable medical devices comprises a lithium anode or its alloys, for example, LiSi, LiAl, LiB and LiSiB. The form of the anode may vary, but preferably it is of a thin sheet or foil pressed or rolled on a metallic anode current collector.

[0053] The cathode for a primary cell is an electrically conductive material, preferably a solid material. The solid cathode may comprise a metal element, a metal oxide, a mixed metal oxide, a metal sulfide, and combinations thereof. A preferred cathode active material is selected from silver vanadium oxide, copper silver vanadium oxide, manganese dioxide, cobalt nickel, nickel oxide, copper oxide, copper sulfide, iron sulfide, iron disulfide, titanium disulfide, copper vanadium oxide, and mixtures thereof.

[0054] Before fabrication into an electrode for incorporation into an electrochemical cell 10, 10A, the cathode active material is mixed with a binder material such as a powdered fluoro-polymer, more preferably powdered polytetrafluoroethylene or powdered polyvinylidene fluoride present at about 1 to about 5 weight percent of the cathode mixture. Further, up to about 10 weight percent of a conductive diluent is preferably added to the cathode mixture to improve conductivity. Suitable materials for this purpose include acetylene black, carbon black and/or graphite or a metallic powder such as powdered nickel, aluminum, titanium, and stainless steel. The preferred cathode active mixture thus includes a powdered fluoro-polymer binder present at about 3 weight percent, a conductive diluent present at about 3 weight percent and about 94 weight percent of the cathode active material.

[0055] The cathode may be prepared by rolling, spreading, or pressing the cathode active mixture onto a suitable cathode current collector. Cathodes prepared as described are preferably in the form of a strip wound with a corresponding strip of anode material in a structure similar to a jellyroll or a flat-folded electrode stack.

[0056] A primary electrochemical cell includes a nonaqueous, ionically conductive electrolyte having an inorganic, ionically conductive salt dissolved in a nonaqueous solvent and, more preferably, a lithium salt dissolved in a mixture of a low viscosity solvent and a high permittivity solvent. The salt serves as the vehicle for migration of the anode ions to intercalate or react with the cathode active material. Suitable salts include LiPF.sub.6, LiBF.sub.4, LiAsF.sub.6, LiSbF.sub.6, LiClO.sub.4, LiO.sub.2, LiAlCl.sub.4, LiGaCl.sub.4, LiC(SO.sub.2CF.sub.3).sub.3, LiN(SO.sub.2CF.sub.3).sub.2, LiSCN, LiO.sub.3SCF.sub.3, LiC.sub.6F.sub.5SO.sub.3, LiO.sub.2CCF.sub.3, LiSO.sub.6F, LiB(C.sub.6H.sub.5).sub.4, LiCF.sub.3SO.sub.3, and mixtures thereof.

[0057] Suitable low viscosity solvents for a primary system include esters, linear and cyclic ethers and dialkyl carbonates such as tetrahydrofuran (THF), methyl acetate (MA), diglyme, triglyme, tetraglyme, dimethyl carbonate (DMC), 1,2-dimethoxyethane (DME), 1,2-diethoxyethane (DEE), 1-ethoxy, 2-methoxyethane (EME), ethyl methyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, diethyl carbonate, dipropyl carbonate, and mixtures thereof. High permittivity solvents for a primary system include cyclic carbonates, cyclic esters, and cyclic amides such as propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate, acetonitrile, dimethyl sulfoxide, dimethyl, formamide, dimethyl acetamide, ?-valerolactone, ?-butyrolactone (GBL), N-methyl-pyrrolidinone (NMP), and mixtures thereof. The preferred electrolyte for a lithium primary cell is 0.8M to 1.5M LiASF.sub.6 or LiPF.sub.6 dissolved in a 50:50 mixture, by volume, of PC as the preferred high permittivity solvent and DME as the preferred low viscosity solvent.

[0058] Regardless of whether the electrochemical cell 10, 10A is a primary or secondary system, in order to prevent internal short circuit conditions, the cathode is separated from the anode by at least one separator 34, 36 and 38. A suitable separator is preferably made of a fabric woven from fluoropolymeric fibers including polyvinylidine fluoride, polyethylenetetrafluoroethylene, and polyethylenechlorotrifluoroethylene used either alone or laminated with a fluoropolymeric microporous film, non-woven glass, polypropylene, polyethylene, glass fiber materials, ceramics, polytetrafluoroethylene membrane commercially available under the designation ZITEX (Chemplast Inc.), polypropylene membrane commercially available under the designation CELGARD (Celanese Plastic Company, Inc.) and a membrane commercially available under the designation DEXIGLAS (C. H. Dexter, Div., Dexter Corp.).

[0059] The lid 16 has an opening that is sized to receive the co-axial GTMS 12, 12A of the present invention connected to the anode electrically isolated from the cathode. An additional opening is provided for electrolyte filling. The casing 26 is thereafter filled with the electrolyte described hereinabove and hermetically sealed such as by close-welding a titanium plug over the fill hole, but not limited thereto.

[0060] It is appreciated that various modifications to the inventive concepts described herein may be apparent to those of ordinary skill in the art without departing from the spirit and scope of the present invention as defined by the appended claims.