CA1157087A

CA1157087A - Anode structure for an electrochemical cell

Info

Publication number: CA1157087A
Application number: CA000379170A
Authority: CA
Inventors: Roger K. Freeman; Franz Goebel
Original assignee: GTE Products Corp
Current assignee: Osram Sylvania Inc
Priority date: 1980-06-13
Filing date: 1981-06-05
Publication date: 1983-11-15
Also published as: JPS57500758A; EP0053134B1; US4283470A; EP0053134A4; WO1981003717A1; EP0053134A1; DK60182A

Abstract

ANODE STRUCTURE FOR AN ELECTROCHEMICAL CELL
ABSTRACT OF THE DISCLOSURE
An anode structure for a cylindrical primary electrochemical cell. The anode structure in accor-dance with the invention includes a thin, circular, lithium metal disc having a central opening therein, and a small, thin, resilient, metal (e.g., nickel) contact member secured to the lithium disc. The metal contact member is of a generally circular configuration and has a flat central portion with a circular opening therein aligned with the opening in the lithium disc.
The contact member has a plurality of tab portions extending outwardly from, and spaced at regular inte-vals about, its outer periphery, and a pair of spikes or barbs depending from opposed ends of each tab por-tion. The spikes are pressed into the soft lithium disc at points spaced from the opening therein for permanently securing the contact member to the disc.
The contact member further has a plurality of notches spaced at regular intervals about the perimeter of the central opening thereby to define a plurality of resilient, deflective portions intermediate to the notches. The deflective portions lie in a flat, common plane with each of the deflective portions having an exposed edge facing a central axis of the contact member.

Description

~-230~'~3 ~ f ~17 ANODE STRUCTURE FOR AN ELECTROCHE~.ICAL CELL
CROSS-REFERENCE TO RELATED APPLICATIONS
In co-pending application number 379,081-9, filed concurrently nerewith in the names of Franz Goebel and William T. McHugh, and entitled "ELECTRO-CHEMICAL CELL", there is disclosed and claimed an electrochemical cell similar to an electrochemical cell as disclosed in the present application.
In co-pending application number 379,105-0, filed concurrently herewith in the names of John E.
Barnes, Franz Goebel and William T.McHugh, and entitled "INTEGP~ATED CARBON/INSULATOR STRUCTURE AND ~T~OD FOR
FABRICATING SAME", there is disclosed and claimed an integrated carbon/insulator structure as may be used in the electrochemical cell as disclosed in the pre-sent application.
In co-pending application number 379,133-5, filed concurrently herewith in the name of Franz ~oebel, and entitled "METHOD FOR ASSEMBLING AN ELEC-TROCHEMICAL CELL", there is disclosed and claimed amethod for assembling the electrochemical cell as d.isclosed in the present application.
BACKGROUND OF THE INV~NTION
The present inventi.on relates to an anode struc-ture for an electrochemical cell and, more particular-ly, to an anode structure for a primary electrochemi-cal cell of a cylindrical design and includi.ng a stacked array o~ cell components.
Primary electrochemical cells are utilized for a wide variety o~ applications and are com-,nonly available in a large assortment of si.zes and shapes.
One well known type of primary electrochemical cell is a so-called cylindrical cell. A parti.cularly suitable desigll for such a cell, especially for high '~;

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` ,J '- 230~3 -2-U~3'7 rate (greater than 1 mA/cm ) and low-temperature (to -40~C) applications, is described in the aforementioned co-pending application number 379,081-9. The cell des-cribed in the co-pending application includes a battery stack disposed within a metal housing of the cell to-gether with an electrolytic solution. The battery stack comprises a large number of thin, generally circular, annular-shaped components. These components are superimposed on each other in a vertical stacked array relative to the housing and relative to a cen-tral, elongated, cylindrical, metal terminal member which extends completely through the battery stack and is encircled by the battery stack components.
The components of the battery stack include a plurality of anode structures and a plurality of carbon current collector electrode/separator assem-blies arranged in the array in alternation with the anode structures. The elongated metal terminal mem-ber may be a solid rod or, in the case of a cell of large physical size, a perforated hollow tube for increasing exposure of the stack to electrolytic solution. Each of the anode structures includes a thin metal disc, for e~ample, of lithium, and a con-tact member adjacent to a central opening in the ~5 disc. The contact member has a central opening align-ed with the opening in the disc and a plurality of resilient portions defined by said central opening by which the anode structure can be forced onto the end of, and along, the central terminal member to its required position in the stack. When in position, the resilient portions of the contact member grip onto the central terminal member to make direct physical and electrical contact therewith. Each of the carbon current collector electrode/separator ~, , ,;

, D-23043 ~3~ 7 `

assemblies as employed in the abovedescribed cell includes a pair of thin carbon/fiberglass cathode structures physically adjacent to opposite sides of a thin metal (e.g., nickel) current collector disc.
~hese latter components have central openings of a size to space, or electrically isolate, the compo-nents from the central terminal member. The current collector disc is of a size and configuration so as to make direct physical and electrical contact with the interior wall of the housing of the c~ll.
~ he electrochemical cell as described herein-above may be assembled by first assembling the entire ~attery stack relative to the central terminal mem-ber outside of the housing and then placing the en-tire battery stack into the housing or, alternatively,by assembling the components of the battery stack one by one relative to the central terminal member within the housing of the cell. While either assembly method produces generally satisfactory results, it is possible as the battery stack is built up for one or more of the cell components, especially the anode structures which are secured to the central terminal member at the centers thereof, to flare up at the outer edges. This flaring up of the outer edges of - 25 the anode structures is due to the fact that the anode structures themselves are very thin and light-weight, as are the other components on opposite sides of the anode structures, as a rjesult of which insuf-ficient comPressive forces exist at the outer edges o~ the anode s-tructures to keep them in a flat position. This flaring up of the outer edges of the anode structures tends to increase in a direction from the bottom of the stack to the top of the stack.
As a result, the overall ba-ttery stack may be less flat and co~pact than required, ancl undesirable gaps ~: .

~-23043 -4~ ~7~'7 or spaces may exist between various ones of the compo-nents, leading to the possibility of breakage of one or more of these components.
BRIEF SUMMARY OF THE INVENTION
_ Accordingly, the present invention provides a con-tact member comprising: a resilient metal member of a predetermined thickness and configuration and having a plurality of spikes depending therefrom at its periphery and further having a major opening therein and a plural-ity of other openings at the perimeter of the ma~or open-ing defining a plurality of resilient, deflective portions intermediate to said other openings and each having an e~posed edge.
The present invention further provides an anode structure for an electrochemical cell, comprising: a metal disc of a predetermined thickness and having an opening therein; and a resilient, metal contact member of ~ pxedetermined thickness and configuration and having a plurality of spikes depending therefrom at its periphery and inserted into the metal disc at points spaced from the opening in the metal disc for securing the contact member to the metal disc, said metal contact me~ber fur-ther having a major opening therein adjacent to the open-ing in the metal disc and a plurality of other openings at the perimeter of the major opening defining a plural-ity of resilient, deflective portions intermediate to said other openings.
BRIEF DESCRIPTION OF THE DR~WING
Some embodiments of the invention will now be describ~d, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 is an elevated view, partly in cross section, of a primary electrochemical cell employing :
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a plurality of anode structures in accordance with the present invention;
FIGS. 2 and 3 are greatly enlarged top and cross-sectional views, respectively, of an anode structure a~ utilized by the electrochemical cell of FIG. l;
FIGS. 4 and 5 are greatly enlarged top and cross-sectional views, respectively, of a carbon current collector electrode/separator assembly utilized by the electrochemical cell of FIG. l; and FIG. 6 illustrates a step employed in the assembly of the anode structures and other cell components into the electrochemical cell of FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to FIG. 1, there is shown a primary electrochemical cell 1 employing a plurality o~ anode structures 15 in accordance with the present invention. The electrochemical cell 1 as shown in FIG. 1 generally includes an elongated cylindrical metal case or housing 2, for example, of stainless steel, within which a battery stack 3 is disposed and insulated from the metal housing 2 by means of a suitable insulator 4 at a bottom end of the housing.
The housing 2 of the cell 1 further includes an :
electrolytic solution 5 in contact with the battery stack 3. This solution may include a reducible solu-ble cathode such as thionyl chloride and an electro-lyte solute such as lithium tetrachloroaluminate dissolved in the thionyl chloride.
The battery stack 3 as employed within the cell 1 comprises a large number of thin, generally circu-lar, annular-shaped components which are superimposed directly on each other in a vertical stacked array relative to the housing 2 and relative to a terminal assembly 6 which extends completely and centrally through the ~attery stack 3 and is encixcled by the D-23043 -6- ~ :

aforesaid components. The terminal assembly 6, which will be described in greater detail hereinafter, comprises a slotted elongated metal tube 6a, shown more clearly in FI~. 6, and a solid metal rod 6b, of the same len~th as, and disposed within,the tube 6a.
The tube 6a and the rod 6b, which may be of nickel, are restrained at the bottom ends thereof within a detent 7 in the insulator 4. The tube 6a is connected at its top end by a thin metal strip 8 t.o a metal terminal 10 of the cell 1. The metal strip 8, which may be of nickel, is typically connected to the tuibe 6a of the assembly 6 and to the terminal 10 hy spot welds and is connected to the terminal 10 by way of a standard insulative glass or ceramic-to-metal seal 12 provided within an hermetically sealed cap 13 of the cell 1. As will be more readily apparent herein-after, the terminal assembly 6, the metal strip 8 and the terminal 10 collectively represent one of the electrical terminals for the cell 1.
The various stacked components of the battery stack 3 as mentioned hereinabove ~enerally include a plurality of anode structures 15 in accordance with the invention, and a plurality of carbon current collector electrode/separator assemblies 16 arranged in the array in alternation with the anode structures 15. Each of the anode structures 15 has a particular form as shown in FIGS. 2 and 3, and each of the car-bon current collector electrode/separatox assemblies 16 has a particular form as shown in FIGS. 4 and 5.
As ind:icated in FIGS. 2 and 3, each of the anode structures 15 in accordance with the invention com-prises a thin, flat, yenerally circular, annular-shaped disc 15a, and a small, generally circular contact memher 15b secured to the disc 15a. A

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~-23043 -7~ ~ ~ f~ 7 suitable material for the disc 15a for use within the cell 1 is an oxidizable alkali metal, such as lithium, and a suitable thickness is 0.005 - 0.006 inch. The contact member 15b, which may be of nickel of a thick-ness of 0.003 - 0.005 inch, is secured to the lithium anode disc l5a by means of several small,downwardly-directed spikes or barbs lSc which are arranged in pairs and depend from opposite ends of a plurality of tab portions 15d. The tab portions 15d extend out-wardly and are spaced around the periphery-of the con-tact member 15b at 90 intervals, and the barbs 15c them~elves are spaced around the periphery of the con-tact member lSb at 45 intervals. The barbs 15c, which typically extend orthogonally from the contact member 15b, are pressed into the lithium disc 15a, as indicated in FIG. 3, and bite into the soft lithium metal for permanent physical and electrical contact therewith. The contact member 15b further has a cir-cular major opening 15e in a flat central portion thereof aligned with a similar, larger opening 15f (FIG. 3) in t~le disc 15a, and a plurality of small openings 15g in the form of triangular-sh~ped nGtches equally spaced about the perimeter of the central opening 15e, for example, at 30 intervals. The notches 15g define a plurality of resilient, deflective portions 15h,or "teeth'l,intermediate to the notches 15g and lying within a flat, common plane ortho~onal to a central axis A-A (FIG. 3) of the contact mem-ber 15b. Each of the portions 15h further has a sharp contact edge lSj of slight curvature and facing the center of the contact member 15b. The portions 15h of the contact member 15b establish direct physi-cal contact with the terminal assembly 6 and, due to the sharp edges 15j of the portions 15h, bite into the tube 6a of the assembly 6 in numerous places, as .

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indicated in FIG. 1, so as to secure the anode struc-ture 15 in position. The manner in which this contact is established will be described in greater detail hereinafter in connection with FI~. 6. As indicated in ~IG. 1, the diameter of each anode structure 15 is selected to be smaller than the internal diameter of the housing 2 of the cell 1 so as to establish a space between the anode structure 15 and the interior wall of the housing 2 by which the stack 3 can be exposed to the electrolytic solution 5. A suitable diameter ~or the anode structure 15 is 0.850 inch, correspond-ing to a C-size cell. A typical internal diameter for the housing 2 is 0.960 inch. A suitable diameter for the contact member 15b (largest diametric dimension) is 0.250 inch, and a suitable diameter for the opening is 0.128 inch. -.
Each of the aforementioned carbon current collec-tor electrode/separator assemblies 16 as shown in FIGS.
4 and 5 generally includes a thin, circular, notched metal current collector substrate 20, and a pair of integrated carbon/insulator structures 22 on opposite sides of the current collector substrate 20. The in-tegrated carbon insulator structures 22 as shown in FIGS. l and 5, although forming part of the electrode/
separator assembly within the cell 1, both physically and actively, are not secured to the current collector substrate 20 but rather are only in direct physical contact with the substrate 20 when assembled into the cell 1. The current collector substrate 20 as employecl by the cell 1 and shown in FIGS. 4 and 5 takes the form of a generally thin, circular, flat disc of a metal such as ;nickel having a circular central opening 20a (FIG. 5) and a plurality of openings 20b in the form of curved notches spaced around its periphery at regular intervals and defining small arcuate :

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~ ~-230~3 -9~ 7~t7 peripheral portions 20c intermediate to the notches.
The opening 20a in the substrate 20 is of a diameter ~reater than the diameter of the terminal assembly 6 so as to establish a spacing, and to be electrically isolated from, the terminal assembly 6 when the sub-strate 20 and the associated carbon/insulator struc-tures 22 are assembled together into the cell 1. The notches 20b serve to establish multiple passageways by which the electrolytic solution 5 is ~ble quickly and readily to permeate porous components of the battery stack 3. In addition, and as will be more fully explained hereinafter, the notches 20b enable the peripheral portions 20c to be deflected upwardly during assembly of the cell 1 whereby sharp edges of the portions 20c are able to bite into the interior wall of the housing 2 and, as indicated in FIG. 1, mc~ke direct physical and electrical contact with the wall of the housing 2 in numerous places. The diameter of the substrate 20 prior to insertion into the housing

2 is slightly greater than the internal diameter of the housing 2 so as to permit upward deflection of the arcuate portions 20c when the substrate 20 is inserted into the housing 2.
Each of the carbon/insulator structures 22 used with the abovedescribed current collector substrate 20 comprises, as shown in FIG. 5, an arrangement of a thin porous insulator sheet or disc 22a physically and permanently integrated with a porous carbon layer or disc 22b. The porous insulator disc 22a is of an electrically-nonconducting material such as fiberglass and serves as a separator for electrically isolating the associated porous carbon disc 22b from an immedi-ately ad~acent one of the lithium anode structures 15.
The porous carbon disc or layer 22b comprises an aggregation oE porous globules or conglomerates D-23043 -10~ 7 containing carbon black and a binder such as "Teflon"*
and having a network of electrolyte-conducting channels formed throughout its entire mass for permitting the electrolytic solution 5 to permeate the layer 22b and the associated insulator disc 22a. For purposes of assembly within the cell 1, the porous insulator disc 22a and the porous carbon layer 22b have respective circular central openings 22c and 22d of the same size as, and aligned with, the opening 20a in the current collector substrate 20a for providing a space between these elements and the assembly 6 when assembled with-in the cell 1.
The carbon/insulator structures 22 as described hereinabove are described in detail in the aforemen-tioned co-pending application number 379,105-0 to which reference may be made for specific details. The cur-rent collector substrate 20 as described hereinabove is described in detail in the aforementioned co-pend-ing application number 379,081-9 to which reference may be made for specific details. Suitable thicknesses for the porous insulator disc 22a and the porous car-bon layer 22b are 0.005 and 0.007 inch, respectively.
A suitable thickness for the current collector sub-strate 20 is 0.003 inch.
The electrochemical cell 1 as described herein-above is assembled in the following manner. First, the anode structures 15, the current collector sub-strates 20 and the carbon/insulator structures 22 are dropped down in proper sequence~over the tube 6a of the terminal assembly 6 so as to generally loosely encircle the tube 6a. ~s indicated in ~IG. 6, the openings 15e in the contact members 15b of the anode structures 15 are slightly larger than the diameter of the tube 6a so as to establish a small space there-between but not as large as the spaces established *Trademark ~' -:

D-23043 -11~

between the other components of the battery stack 3 ar~d the tube 6a, which other components have openings o considerably larger size than the openings 15e in the contact members 15b of the anode structures 15.
S As also indicated in FIG. 6, the above assembly oper-ation is performed externally of the housing 2 OL the cell 1.
Once the abovedescribed cell components have been assembled around the tube 6a, the anode structures 15 in the stack are caused to be secured to the tube 6a.
To accomplishllthis operation, the tube 6a as employed ~t this pointlis selected to be a permanently expand-able member which makes physical contact with the anode structures 15, specifically, the contact members lSb thereof, when in its expanded state but not when in its non-expanded state. To expand the tube 6a, -- the aforementioned elongated metal rod 6b is inserted into and pushed longitudinally down through the tube 6a, as indicated in FIG. 6. The rod 6b initially has a diameter greater than the inside diameter of the tube 6a, for example, a diameter of 0.062 inch as compared with an initial inside diameter of 0.052 inch for the tube 6a. A suitable initial outside diameter for the tube 6a is 0.126 inch (representing a wall thickness for the tube 6a of 0.032 inch). When the rod 6b is pushed down the tube 6a, the tube 6a, which has a generally C-shaped cross section by vir-tue of the provision of a slot 6c therein, is caused to expand outwardly in a permanent fashion. The rod 6b is left permanently within the tube 6a, as indicaied in FIG. 1, so as to insure that the tube 6a remains in its expanded state. As the tube 6a expands out-wardly, the forces of the outward expansion are distributed more or less evenly to the resilient deflective portions l5h of each of the multiple ~ .

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D-23043 -12- ~ 7 contact members 15b, in succession, as the rod 6b is progressively advanced past successive ones of the anode structures 15 along the length of the tub~ 6a.
The forces against the contact edges 15j of the portions 15h, which lie in a flat, common plane as previously mentioned, cause the portions 15h variously to be deflected upwardly and/or downwardly in a random fashion relative to the tube 6a. The edges 15j of the portions 15h following the deflection of the portions 15h (at the termination of the expansion operation) bite into the tube 6a in numerous places, as indicated in FIG. 1, thereby locking the anode struct~res in poæ ~ion. The outward expansion of the tube 6a does not affect the other cell components since, as pre- -viously mentioned, the central openings in-these com-ponents are considerably larger than the openin~s lSe in the contact members 15b of the anode structures 15.
A suitable slot width (non-expanded) for the tube 6a as described hereinabove is 0.010 inch.
The above expansion operation by which the anode structures 15 are secured to the tube 6a results in a stacked array of components which is very compact and devoid of unwanted spaces or gaps between the com-ponents constituting the stack due to flared or up-turned edges. The possibility of breakage of the componants is therefore substantially reduced. For physically large cells, the rod 6b as described here-inabove may be replaced b~ a hollow tube (without a slot) and, in addition, both of the tubes may be perforated for faciIitating the exposure of the battery stack to the electrolytic solution when assem-bled into the housing 2 of the cell.
Once the anode structures 15 have been secured to the terminal assembly 6 as described hereinabove, various standard resis-tance measurement tests may be , .

- ~-23043 -13- ~7~ 7 made on the stack of components to detect any unwanted short circuit conditions, ~or example, short circuit conditions between the carbon current collector electrode/separator assemblies 16 and the terminal assembly 6 and/or the anode structures 15. Assuming that no such short circuit conditions exist, the assembly of the battery stack components and the ter-minal assembly 6 can then be inserted into the housing 2 of the cell 1 and electrolytic solution added to the cell. The insertion operation is performed by simply pushing the entire assembly of cell componen-cs and the terminal assembly 6 longitudinally into and along the housing 2. As the assembly is pushed into the housing 2, the arcuate portions 20c of the substrates 20 are caused to turn, or be deflected, upwardly slightly by v~rtue of physical contact with the inte-rior wall of the housing 2. At the same time, the arcuate porti~ns 20d are caused to move slightly to-ward each other as the individual substrates 20 con-form to the internal diameter and configuration ofthe housin~ 2. When the multiple substrates 20 have all been inserted into the housing 2, the upturned, deflected arcuate portions 20c, by virtue of their sharp edges, bi~e into the interior wall of the housing 2 in numerous places, as indicated in FIG. 1, so as to secure the substrates 20 in position and make physical and electrical contact with the housing 2.
When~the abovedescribed battery stack assembly has been positioned within the cell 1 and exposed to electrolytic solution as discussed hereinabove, the electrolytic solutio~ (e.g., cathodelectrolyte solu-tion) is readily ab]e to diffuse into the stack and permeate the porous components thereof. The ~low of the electrolytic solution to the components of the stack is ~acilitated by the aforedes~ribed numerous .

D-23043 -14~ 7~ ~

notches 20b formed in the current collector substrates 20 and ad~acent to the interior wall of the housing and by the spaces established be~ween the -omponents l~f the stack and the interior wall of the housing 2 and the terminal assembly 6. As previously mentioned, the flow of electrolytic solution to the battery stack

3 can be further increased, especially in the case of a physically large cell, by the use of hollow, elonga-ted tubes in lieu of the non-perforated tube 6a and the solid rod 6b, in which case the electrolytic solu-tion is able to further penetrate the battery stack 3 by way of the perforations in the tubes. Irrespective of the particular manner in which the electrolytic solution reaches the battery stack, the electrolytic solution diffuses into the multiple carbon discs 22b by way of the network of electrolyte-conducting channels formed therein and also diffuses into the ~ -multiple porous discs 22a. The physical and electri-cal connection of the multiple anode structures 15 to the terminal assembly 6 establishes that assembly and the metal strip 8 and the terminal 10 connected there-with as the negative terminal of the cell 1. The physical and electrical connection of the multiple substrates 20 to the interior wall of the housing 2 establishes the housing 2 as thepositive terminal of the cell 1.
While there has been described what is considexed to be a preferred embodiment of the invention, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the invention as called for in the appended claims.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A contact member comprising:
a resilient metal member of a predetermined thickness and configuration and having a plurality of spikes depending therefrom at its periphery and further having a major opening therein and a plurality of other openings at the perimeter of the major opening defining a plurality of resilient, deflective portions intermediate to said other openings and each having an exposed edge.

2. A contact member in accordance with claim 1 wherein:
the resilient, deflective portions of the metal member lie in a flat, common plane.

3. A contact member in accordance with claim 1 wherein:
the major opening in the metal member is circular and located centrally in the metal member; and the plurality of other openings are of like size and shape and spaced at regular intervals about the perimeter of the major opening thereby to define resilient, deflective portions of like size and shape intermediate to said plurality of other openings.

4. A contact member in accordance with claim 3 wherein:
the plurality of other openings are spaced around the perimeter of the major opening at regular intervals of 30°.

5. A contact member in accordance with claim 4 wherein:
the plurality of other openings are in the form of triangular-shaped notches.

6. A contact member in accordance with claim 1 wherein:
the metal member has a plurality of tab portions extending outwardly from and spaced about its periphery; and the plurality of spikes includes a pair of spikes at opposite ends of and extending away from each of the tab portions.

7. A contact member in accordance with claim 6 wherein:
the tab portions are spaced about the periphery of the metal member at regular intervals.

8. A contact member in accordance with claim 7 wherein:
the tab portions are spaced about the periphery of the metal member at intervals of 90°
and the spikes occur at intervals of 45°.

9. A contact member comprising:
a generally circular, resilient, metal member of a predetermined thickness and configuration and having a plurality of tab portions spaced at regular intervals about its periphery and a pair of spikes at opposite ends of, and depending from, each tab portion, said metal member further having a flat central portion and a circular major opening located centrally within said flat portion and a plurality of notches of like size and shape spaced at regular intervals about the perimeter of the major opening thereby to define a plura-lity of resilient, deflective portions of like size and shape intermediate to said notches and lying within a flat, common plane.

10. A contact member in accordance with claim 9 wherein:
the metal member is of nickel having a thickness in range of 0.003 - 0.005 inch;
the tab portions are spaced about the periphery of the metal member at regular intervals of 90°;
the spikes occur at intervals of 45°, and the notches are spaced about the perimeter of the major opening at regular intervals of 30°.

11. An anode structure for an electrochemical cell, comprising:
a metal disc of a predetermined thickness and having an opening therein; and a resilient, metal contact member of a predeter-mined thickness and configuration and having a plurality of spikes depending therefrom at its periphery and inserted into the metal disc at points spaced from the opening in the metal disc for securing the contact member to the metal disc, said metal contact member further having a major opening therein adjacent to the opening in the metal disc and a plurality of other openings at the perimeter of the major opening defining a plurality of resilient, deflective portions intermediate to said other openings.

12. An anode structure in accordance with claim 11 wherein:
the metal disc is of an oxidizable alkali metal.

13. An anode structure in accordance with claim 12 wherein:
the metal disc is of lithium.

14. An anode structures in accordance with claim 13 wherein:
the metal contact member has a flat central portion and the major opening and the other open.ings are located in said flat portion whereby the resilient deflective portions of the contact member lie in a flat, common plane.

15. An anode structure in accordance with claim 14 wherein:
the opening in the lithium metal disc is circular; and the major opening in the contact member is circular and smaller than, and coaxial with, the opening in the lithium metal disc; and the plurality of other openings at the perimeter of the major opening are of like size and shape and spaced at regular intervals about the perimeter of the major opening in the contact member thereby to define resilient, deflective portions of the same size and shape intermediate to the plurality of other openings and each having a curved exposed edge.

16. An anode structure in accordance with claim 15 wherein:
the contact member has a plurality of tab portions extending outwardly from and spaced about its periphery; and the plurality of spikes include a pair of spikes at opposite ends of and extending away from each of the tab portions.

17. An anode structure in accordance with claim 16 wherein:
the plurality of other openings at the perimeter of the major opening are in the form of notches and spaced about the perimeter of the major opening at regular intervals of 30°;
the tab portions are spaced about the periphery of the contact member at regular intervals of 90°; and the spikes occur at regular intervals of 45°.

18. An anode structure in accordance with claim 17 wherein:
the lithium disc is generally circular in config-uration, and has a thickness in a range of 0.005 - 0.006 inch; and the contact member is of nickel and has a thickness in a range of 0.003 - 0.005 inch.