CA1157085A

CA1157085A - Battery cell construction and method of forming

Info

Publication number: CA1157085A
Application number: CA000379377A
Authority: CA
Inventors: George C. Shay
Original assignee: Corning Glass Works
Current assignee: Corning Glass Works
Priority date: 1980-07-11
Filing date: 1981-06-09
Publication date: 1983-11-15
Also published as: US4310607A; JPS5746476A; EP0044180A1

Abstract

Abstract of the Disclosure A cell for generating electric energy is provided comprising a sealed container partitioned into anode and cathode chambers, said partition comprising an electrolyte/
separator in the form of a bundle of hollow glass or ceramic fibers, fusion sealed together between their inter-stices adjacent at least one end thereof. Preferably, the ends of the fibers which project within the anode chamber are sealed closed whereas the opposite ends are in open communication with the cathode chamber. Preferred anode and cathode materials comprise an alkali metal such as sodium or potassium and sulfur respectively.

Description

~1~7V85 SHAY. 8 BA~TERY C T-T- CONSTRUCTION
AND METHOD OF ~ORMING

3ackground of the Invention Recent battery technology, such as is set forth in ~.S.
Patent No..3,476,602 discIoses the use of a molten alkali metal anode/anolyte and a m~lten sulfur~alkali metal sulfide catho.lyte separated by an alkali metal ion-permeable mem-brane/electrolyte. A cathodic current collector, or "cathode"
is immersed in the catholyte. ~hen the anode and cathode are connected through an external. electrical circuit, the ele~trons axe discharged to the cixcuit f~om the anode with the formation of positively chaxged alkali.metal ions.
These ions migrate through the membrane into the catholyte.
Negatively charged sulfide (polysulfide~ ions are formed in the catholyte by interaction of sulfur at the cathode sur-face-with electrons recei~ed from the external circuit.
In one embodiment of such a battery, the membrane is in the form of a multiplicity o~ sodium-filled hollow glass : fibers closed at o.ne end and open at the other. The open ends of the fibers communicate with a reservoir of molten sodium and the fibers are immersed in a molten polysulfide catholyte, with the anolyte (.sodium) and catholyte being separated by a tubesheet or header which encompasses a porti.on of the fibers in a sealing arrangement. That is, the glass and glass-ceramic hollow ~ibers or other electrolyte separators are sealed in place as a bundle in a header by adhesives such as glazing or potting compounds, solder glass, and the like materials. A large anode area may be afforded by closely spacing a large number of the fine hollow fibers in a gi~en cell or battery volume.

-1- .

:~5~7(~85 U.S. Patent No. 4,112:,.2~ discloses a battery cell having a large number o~ fine.hollow glass fiber lengths, with their lower end closed and their upper ends open, pass-ing through a tubesheet in sealing arrangement therewith.
The open ends o~ the fibers communicate with a molten alkali metal in an anolyte cup and the portions of the fibers below and depending. downwardly f~om the tubesheet are immersed in a corresponding alkali metal polysulfide melt. The fiber len~ths are dlsposed generally parallel to one another in a continuous spiral of generally concentric. vertical rows and constitute a generally cylindrical bundle.
Dispo.sed be.tween the rows o* fi~ers wi~hin the hundle and wrapped around the bundle at least once is a cathodic current collector consisting of a thin, flexible, elongated sheet of metal or metal alloy, such as aluminum foil, pre-ferably protectiveIy coated with g~aphite or molybdenum disulfide. The cathode sheet may be pierced by perforations to ~acilitate catholyte fiow into and out of the spaces between the cathode sheet-and the fibers, and the sheet is suitably connected to a catholyte lead for connecting the batte~y ceIl to an external electrical circ~it. In a like manner, an anode lead passes through the top of the anolyte cup and is utilized to connect the battery cell to an external elect~ical circuit.
Th~ tubesheet or heade~ of the prior art which joins the hollow fibers together and pr.ovides a. seal between the sodium anode and the sodium sul~.ide cathode chambers, is generally formed of a frit or solder glass material which is softer than the hollow capillary fibers. When the frit or solder glass is fired, it fuses into a porous mass and seals to the outer walls of the hollow fibers without softening ~57~35 th~ fi~ers, however the por.ous. natu~e o~ the resulting tube-sheet promctes leakage, a~d the expansion dif~erence between the tubesheet glass and the glass o~ the fibers promotes the breakage of such ibe~s. ~urther, the .~ofter tubesheet glass may yield or flo~ excess.ively at battery cell operating temperatures which'may b~ in excess-of.300C in larger s.ized cells. Further, i~ view o~ the aluminum foil interposed between rows of.such capilla~y fibers, the bun~le of fibers is rather ragile s.ince each fiber is only connected at one end to the tubesheet and hangs freely downwardly therefrom.
Unite~ Kingdom Patent Application No~ GB2~17391A, published O¢tober 3, 197~, entitled A Sodium~Sulphur Cell, addres.ses itseI to the~p~.oblems of suspending a plurality of hollow open ended f.ibers from a tubesheet, and proposes to overcome s.uch problems by positioning a metal wire within each f.iber and seal.ing the ibers at both ends, with the metal wire emb.edded with~ and projecting outwardl.y from at least one sealed end of the fiber. As pointed out by the published application, an appropriate connection can be made between the seal.ed fibe~ and a clos.ing plate for the cell in a manner capabIe of withs.tanding great mechanical strain and with ewer breakage problems, by closing the end o~ the fiber to. be sealed and by seal.ing the conductor wire in the closed end and in~o the closing plate. It is thus possible, according t~ the published application, to fusion seal one closed end of the fiber having a wire passing therethrough direc~ly to a clos.ing plate for the battery cell. Thus, each'fiber becomes an indi~idual closed chamber, which chambers are not in open communication with one another.
It thus has been an object o~ the present invention to provide an alkali metal~sulfur cell or battery in which the ~7~S~

standard tubesheet which separates the anolyte and catholyte is eliminated as such, by fusing the outer walls of hollow fibers forming the ion-permeable electrolyte together as a solid sealing mass adjacent open ends thereof, in such a manner so as to fill the interstices between such fibers with the glass composition of the fibers while retaining the interiors of such fibers in open communication with an adjacent chamber.
A further object of the invention has been to provide an alkali metal/sulfur cell or battery wherein the hollow fibers of the bundle forming the ion-permeable membrane or electrolyte are sealed together along adjacent portions of their longitudinal extent intermediate their ends to form a rigid fiber bundle, and such fibers are each provided internally with a cathode lead or cathodic current collector in the form of a wirelike member.

Summary of the Invention The present invention provides a battery cell for generating electrical energy which includes container means having anode and cathode chambers. The anode and cathode chambers are separated by a combination electrolyte/separator. This electrolyte/separator is in the form of a bundle of hollow fibers having inner and outer surfaces positioned substantially parallel to one another along their longitudinal extent. The interiors of said hollow fibers are open at one end of the separator bundle and sealed closed at the opposite end thereof. The hollow fibers forming the separator bundle have interstices formed along their outer longi-tudinal surfaces between adjacent hollow fibers. Wall portions of adjacent hollow fibers forming the separator bundle are sealed together adjacent the open end thereof to form a solid sealing mass of the same composition as the hollow fibers closing off the interstices between the hollow fibers adjacent their open ends.

The outer surfaces of the hollow fibers extend into one of the ~' .

i7~35 ..

chambers with the interior of the hollow fibers being closed off therefrom by the sealed ends. The inner surfaces of the hollow fibers are in open communication with each other and the other chamber, with the open ends of the hollow fibers opening into the outer chamber. An anolyte communicates with one surface of the separator bundle and a catholyte communicates with an opposite surface of the separator bundle. The longitudinally extending cathodic current collecting means within the container means extends substantially along the length of the hollow fibers and is surrounded over a major portion of its extent by the catholyte.
Anodic current collecting means are present.
The present invention further provides a method of making a battery cell having a first oxidizable liquid metal electrode, a second fluid reducible electrode and a substantially fluid tight electrolyte/separator separating the first and second electrodes.
The electrolyte/separator is in the form of a plurality of hollow fibers. A plurality of longitudinallv extending hollow fibers having open ends is formed and one end of each of the hollow fibers is sealed off. A bundle of the hollow fibers is formed by juxtapositioning a plurality of the hollow fibers in substantially parallel relationship with the longitudinally extending outer sur-face portions of adjacent hollow fibers contacting one another and with the sealed ends of the hollow fibers being positioned at one end of the bundle and opposite open ends of the fibers being positioned at the opposite end of the bundle. At least a portion of the contacting longitudinally extending outer surface portions of adjacent hollow fibers is sealed together to form a substan-tially rigid separator bundle, with interstices formed between adjacent fibers along their outer longitudinal surfaces. The wall portions of adjacent fibers forming the separator bundle are -4a-. ,~

~S7~5 sealed together adjacent the open ends of the fibers and a solid sealing mass of the same composition as the fibers is formed.
Thus the interstices between the fibers adjacent their open ends are closed off. Current collecting means are positioned within the fibers so as to extend outwardly therefrom through the open ends. The separator bundle is sealed within a battery cell housing with the solid sealing mass positioned substantially at an interface between the first and second electrodes.
The battery assembly of the instant invention comprises a sealed container, which is divided or partitioned into mutually exclusive anode and cathode chambers. Partitioning of the anode and cathode chambers is achieved by means of a solid electrolyte-membrane, sometimes also referred to herein as the electrolyte or separator, in the form of a plurality of hollow fine fibers or capillaries held together as a bundle and sealed together along portions of their length so as to provide rigidity and give the bundle mechanical integrity. The hollow fibers or capillary tubes are sealed closed at one end which projects within the anolyte chamber, and are in open communication at the other end with the catholyte chamber. However, the -4b-, .

!

~7~5 interstices between the h~llow f.ibe~s or capillary tubes are ~used together adjacen~ ~uch:Qpen.ends to ~orm a solid.
sealin~ mass about such'open end~ so that the capillar~
tubes themseIves for~a.uni~orm continuous electrolyte separa~or between the anode and cath~de chambers~ The hollow part o the-capillary tubes, bein~ in open communi-cation with thè cath~lyte chamber, is filled to a desired level with the-catholyte, and a cathodic currert collector wire is positioned within each such hollow capillary tube and passes.outwardly thrsugh'the.o.~en end and is. connected to a cathode lead as.sembly. Th~ bundle of hollow fibers or capillary tubes, bei~s sealed together along a portion of their contact length beyond.the solid.seal.ing mass, pr.ovide a rigid fibe~ structure ha~in~ impr.ove~ struc.tural integxity.
The electrolyte/separator as it is-known, is. usually made of a material such as a polycrystalline ceramic, amor-phous glass or an impregnated matrix., the latter having em~edded therein an es.sentially nonmigrating salt or liquid whic~'is permeab~e onl~r to the ano.de metal ion. The elec-trolyte (separator) is; fult~er characterized as transmittingions of ~he alkali metal anode.between the anode and cathode chambers but as bei'ng substantially non-conducting to electrons.
A liquid alkali metal, such as sodium or potass:ium, is contained within ~he an~de chamber, whereas the cathode chambex contains a r.~ducibIe material, such as sulfur.

Brie~. Description of the 9rawings Fig. 1 is a schemati¢ pers.p.ective view of a bundle of hollow ~.ibers or capillary tubes. embodying the invention wherein the interstices'between such tubes are sealed toget~er adjacent the open end of the tubes.

~ 7 ~ ~ 5 Fig. 2 is a schematic side ele~ational view;o a portion of the capillary tubul~r bundle shown in Fig. 1 illustrating the fusion sealing of the-spaces between the tub:es adjacent the Qpen end of 5uch tubes, P~g~.3 is a greatly enlarged fragmental sectional view of a portion of the bundle.'of Fig.' 2:whIle-lookin~ along lines~3-3 of ~ig. 2,~ but with:the addition of coLlector wires within the capillary of the~ f i~ers or tu~e$ forming such bundle.
Fig.. 3a is a greatly.enlarged fragmental sectional. vie~
o~ a portio~ o~ the bundle'of Fig. 2 while looking along lin~s.3a-3a o~ Fig. 2.~,hut.~ith:the'addition of collec~or wires. within the'h~llow inte~iors of the fibers forming such bundle.
Fig. 3b .is a greatly enlarged fragmental. elevational view in.s.ection of an up.per portion of the bundle shown in Fig. 2, but with collector wires within the.fibers.
Fig. 4 is a schematic s.ectionaL view in elevation of a battery cell embodying the pre~ent invention.
Fi~.. 5 is a schematic s.ecti.onal. ~iew in eIevation of a further~embod'lment of a cell'i~ acco.rdance with this in~ention.
Fig. 6 is.a sc`hematic eLe~ational view partly in section of an additional. emb.od'iment of a cell in accordance with the inventio~.
Fig. 7 is a schematic sectionaL view in eIe~ation of a still further. emb.odiment of a cell in accordance with the invention.
Fig. 8 is a schematic. ~.ie~. ~llus~rating one method of po~itioning the eLectrode'collector wires within the capillaries.of the bundled hollow f.ibers or capillary tubes..

7S~85 Fig. 9 is a schematic el'e~ationa~ view in.section illus~rating a method o~ formins the capillar~ tubes ~ith a colle~tor w~re there~ithln._ Figs. lO., ll and l~ are.schematic illustrations for forming the capillary bundle~ from the .tubular mem~ers drawn in accordance.wit~'the process6 of Fig. 9~
Fig~- 13 is a sch'emati~ eIe~ational illu~tration parti-ally in se~tion sho~ing a furt~er methad.of fo..min~ the capillary b.undles o~ the pres:ent inventi~n.

Description of the ~eferre~ Embodiments ~ he batte~ry ceIls of thè~present invention may be fabricated as a complete unit comprising the electrolyte (separator~ and electrRdes. in a liq~id and vapor tight container. Co.nveniently, the electrol.y.te/separator may be sealed within a containeri to pr.ovide separate anode and cathode ¢hambers or. compartments. The outer case or con-tainer, or at least a portion thereof comprising one of the compartments, may be f~bricated from an electron conducting . mater.ial and of a str.uc.turaI stabilit~ such that it does not degrade or detrimentally react with battery components during operation. The usq of an eIectron conducting mat.erial facilitates. a.ready connectlon of. collector lead wires.
Fu~ther.,. to as.sure optimum efficiency, the case i9 preferably co.vered ~ith a thermal lnsulating material to minimize heat los:ses. both during cell op~ration and offduty storage, or al.ternatively a iacket of insulating material ha~ing heating wires. or other heating eIements adjacent the case may be used to. co~er part or the entire battery cell.
A pref.erred anade-cathbde electrolyte system of the pres.ent invention comprises a liquid sodium anode and 8~ fi::

liquid sul~ur-sodlum sul~ide mixtur~ as the cathode system, ~c e-.g. a sodium polysulfide, and a sodium ion conductive glass or ceramic eIectrolyte.' The sys.tem is capable of producing '; .
energy densities of o.~er. 3a~ ~att hours per pound~at operating. ^.. ' temper.atures as low as.33~C.: ~-The te~ anode'is: us.ed herein.i~. accordan~e with recognize~ electrochemical and eIectr.ical engineering prac-tices, and.deno.tes, when the cell is acting as a battery, i.e., deIi~ering current to a lo.ad, the eIectrode at which current enters the'cell. T~e term cathode deno.tes th~ elec-trode at which'current leaves the cell.
Details as to iber materials formin~ the separator, catho.~yte compositions, anolyte'compositions, housing sealing glas.ses, and known as.sembIy methQds suitable for the practice o~ tbe pres~ent invention are g.iven in U.'S..~atents Nas...3;,476,6~2;.3,679',48.0 and'4,112,203.
However, whereas the'hollow fibers or capillary tubes forming tbe.electxolyte separator bundle of the prior art were sealed in pla~e.as a bundle in a header or tubesheet by adhes.ives. such'as glazing or pQttlng compounds, solder glass, high'temperature tbermal setting resins and like materials, the walls of the capillary tubes or fibers of tbe present invention are fused t~gether as a sealing mass adjacent tbeir open ends, so that tbe interstices between adjacent .tubes are elimlnated and sealed off, thus forming a unifor~ glass or glass-ceramic composition for ~irtually the entire'separator bundle'whïch.~eparates. the anode and cathode chambers. In additi.on, sin¢e there is no current collector ' positioned between adjacent f.ibers or capillary tubes, the fibers formin~ the'separator bundle'of the present invention are sealed together along portions of their lengths beyond ;7~5 the se~ling mass s~ as to pxovide:the bundle with structural .
integrity.
Referring now to Figs. 1, 2,:.3,".3a and.3b, a sepa~ator bundle 10 is.~shown compris.ing a plurality of h~llow fibers or capillary tubes 12 sealed to~ether along at least portions of their lengths at a~jacent contact areas.l4 le~ving open interstices 16. there~et~een. The :tubes 12. each'have a clos.ed or sealed of end 18 and an open end 20. The open end communicates with the h~llow capillary in~erior 22, which as sh,bwn in Flg..3 is px.ovided.with a current collector 24 which'm~y be'in the ~orm of ~ pro.tectiveIy coated aluminum wire.: The end of the ~undle 10: adj.acent.the open end 20 of the hollow ~i~ers or capillary tubes 12 is us.ed together between the fibers foxming the bundle. Thus the spaces or interstices between the walls of the fibers or tubes forming such bundle'are sealed off and a solid sealing mass 26 is formed between such fibers.adj:acent the open ends thereof.
The solid.sealing mass.26 firmly and rigidly positions the fibers and foxms a uni~onm composition seal of the same glass as the hollow fib-ers between the anode and cathode compartments of the ceIl, which are separated by the tubular eIectrolyte bundle 10,. and therefore there is no thermal expansio~ mismatch between the ~ibers and the sealing mass which could cause cracking o~ ~ractuxe upon heating to or cooling ~ro~ the oper,ating.tempexature of the ceIl. The sealed contact portions 14 extend along portions of the length of fibers 12 beyond sealing mass 26.
The bundle'of hollow capillary fibers or tubes formed in acco.rdance with'the present invention may be assembled into a battery in a variety of structural. embodimen~s. For example, in the embodiment shown in Fig. 4, the separator _g_ ;76~5 . . 1.
bundle 10 is mounted in an upright position with the clos.ed .
sealed o~. ends 18 o~ the hollow fibe~s or capillary tube~
12 at the bottom of the b.undle projecting into an anode chamber 28 of the battery cell.30, and the open ends.20 o~ ';
the fibexs 12 are in open communication ~ith'a catho.de '~
chamber 32.. The anode chamb-e~ 2~ is- formed within an.enclos-ing housing or container 34 which'may be o~ metal. such as stainless steeI, whereas the cathode chamber 32 is formed within a co.nta.iner or hous.ing.36 which may be of a glass or glass-ceramic material.. The anode chamber 28 is pxovided with an anolyte.38 of molte~ alkali metal, such a~ for example sodium, within which the closed end 18 of the'hollow glass f.ibers or capil-lary tubes 12 p~oject. Accordingly, the anolyte 38- flows within.the interstices 16 about the outer sur~.ace of the hollow f:ibers.l2-,. as shown in Fig.... 3b.
; The cathode chamber.32 is open to the hollow interiors 22 of ' fibers 12,. which as shown in ~ig. 3b are provided with a molten catholyte 4a such'as-a molten sodium polysulfide , composition.
~ plurality o cathodic.current collector ~ires 24, which may be protectiveIy coated al'uminum wires, extend outwardIy from the open ends.2Q o~ ho.llow interiors.2~ of the ho.llow ~.ibers or tubes 12 and are pressed together at th~ir oute~. end~ to form a common electrode connector 42 which is. connected to a cathode lead 44. extending through the catho.de hous.ing.36 b~ means of a connecting strap 46.
In a 11kQ manner, a.n anode lead 48 may extend through the anode housing.34 into. the anol~te.38 where housing.34 is of : a non-conducting material, ~ith the cathode lead 44 and the anode Iead 4~ bein~ utiliz.ed to connect~the battery cell 30 to an external electrical circuit. However, where housing 34 is of a conducting: ma~erial, such as stainless:s.teeI, the housing itseI~ may f.unction as the eIectrode.:
T~e hollow fibers or capilla~y tubes 12 forming the separator bundle 10 are rigidly fus.ed togetker between their intersticies. as a sol.id.mass 26 adjacent their open ends 20 which.are in.o*en communication with each other and cathode chamber.3Z and are pro~ided with catholyte 40 (see Figs. 3a and.3b). The catholyte 40 flows into the hollow interiors 22 of the capillary tubes: 12 and surrounds the cathodic current col:lector wire 24-positioned within each such tube.
The separator bundle 10 is sealed to an inner surface of the catho.de hou$ing 36 ~ith any kno~n:suitable'sealing glass-50 such as ~n anhydrous bo.ric:oxide glass modi~ied with 2-3%
soda and siIica to match the'xmal expansions, to provide a glass-to-glass seal between the container.36 and the peri-pheral portions of the'sol.id.sealing mass 26 retaining the fibers or tubes 12 of the se~arator bundle 10. ~n a like . manner, the anode housing.34 is sealed to an outer surface of the cathode hous.ing 36 by:suitable sealing glass 52, similar to:sealing glass 50,. to p~ovide a glass-to-metal : seal between the anode and catho.de hous.in~s.
The battery ceIl 130'.shown in ~lg. 5, is similar to that shown in Fig. 4 with the major. di~erence being in the sealing means between the.anode and cathode housin~s. As shb.wn, the ano.~e housing or container 134 and the cathode housing or con~aLner .136'as~ each pr.ovided with mating oppo~ed flange portions.54,.5~, ses.pectively, having a suit-, able gaske.t:58 positioned therebetween. A compression seal is. effected between the~flanges 54 and 56 of the anode and . 30 cathode hous.ings 134,136 by any suitabIe means 3uch as a ': conventional pipe coupling or clamping means 60. The upper .~

end of the cathode container 136 is provided with a covermember 62 having an inlet opening 64 projecting therethrough.
The cover member 62 is positioned upon an upper peripheral flange portion 66 of the cathode housing 136 with a suitable sealing gasket 68 positioned therebetween and provided with a compression seal by any suitable means, such as the coupling 60.
The separator bundle 10 is secured to an inner surface of the glass or glass-ceramic cathode housing 136 adjacent the fused solid sealing mass portion 26 by means of a suit-able sealing glas-~ 150 providing a glass-to-glass seal.
Although the housing 136 may be sized or contoured at its lower extent to snug~y accommodate the outer periphery of the sepaxator bundle 10, a glass sealing ring 70 may be utilized to accommodate the bundle 10 within the container ` 136 where desired. The sealed end 18 of the hollow fibers 12 foxming bundle 10 project downwardly within an anolyte 138 contained within anode chamber 128 of anode housing 134.
The anode housing or container 134, which is formed of a suitable metal, functions as an anode electrode lead, and is provided with an opening 72 for supplying the anolyte 38 which flows within the interstices 16 about the outer walls of the hollow fibers 12. Fill openings 64 and 72 are of course sealed off by known suitable means after filling has been accomplished.
The hollow interiors 22 of the fibers 12 have a catholyte 40 retained therein and communicate at their opened ends 20 with each other and the cathode chamber 132 of cathode housing 136. A plurality of current collector wires 24, which axe surrounded by the catholyte and project outwardly from within the hollow interiors of capillary tubes 12, , ' ~ 5~

extend upwardly from the o.pen ends.20 of such tubes and are --formed into a common electr.odei connec~or,42 whIch ~s. connected by a strap 46 to a catho.de:lea& 44 exte~ding through an opening in c.o.~er 62.
In the em~odiment shown in Fig. 6, the battery cell 230 is similar tQ the cel'ls shown in.~igs. 4 and.5 exce~t for the fact..that battery ceIl 230 is. in~erted with the anode chamber 228. being in an up~es positi.on and the catho.de chamber 232. being in a l~wer position. An anode housing or container,234- forms the ano.de ch,amber 2~8.which contains an ' anolyte.238, and has an anode lead 4& projecting outwardly ,~ through an upper portion of s.uch hous.ing. The separator bundle lO is sealed to an in~er. surf.ace o~ the anode hous.ing 234. by suitab.le sealing glass 250.to: form a glass-to-metal seal when the anode contai~er 234 is formed of a suitab.le metal. The closed sealed o~. ends 18 of the hollow fibers forming bundle lO proj:ect upwar*ly within anolyte 238 retained within anode'container 234, ~ith the separator bundle being sealed abQut the.periphery of the solid sealing mass 26 . 20 adjacent the open end~-2Q of th~ ~ibers 12 to the anode : housin~ adj.acent a mouth:porti.on the~.eo~.
, Th~ catho.de co~tainer or housing 236, which.may be of a suita~Ie' metal, is ~ormed ~ith a douhle wall constr.ucti.on :. :such. th,~t the anode chambes 228 is positioned partially within.a r.Qces.sed O hollo~ inner. portion 74 ~ormed by an in~er wall 76 o~.the cathode housing 236. Although the anode housing.234 and the cathode housing 236 may be formed of a suitable metal such.as stainless s.teel or a glass or glass.-ceramic material as. desired,,when the housings are bQth formed of metal as shown in FigO 6, an insulating and sealing collar 78 of suita~le'glass or glass-ceramic material ~ ~S7~35 is utiliz.ed to. seal the outer wall of anode hQus.in~ 234 to the inner wall 76 of. cath~.de'hous.in~.`2 6.
The hollo~ interiors.of the capillary fibers or tubes 12. co~municate with the cathode chamber 232 ha~ing a catholyte 24Q.retained therein.. In ~iew .o~ the fact that the up.per leveL 241 of the catholyte'is.maintalned at a. height ab.ove the closea ends 18 o~ the fibers 12,. the hollow. interiors 22 of the fibers are uppli.ed with cathQlyte.240 through open ends.20 of the fibers 12 which are in open communication with catho~e chambe.r 232.. In addition, a plurality of current coll:ector wirea 24,..which are surrounded by the catholyte.'240..within.the hollo~ fibers 12,.. extend outwardly from the open ends.20. o~ s.uch f.iber~.and are combined.together into a common collector 42 which is.attached by means of connecting strap 46 to cathode hous.ing 236 which.~unctions as a catho.de lead>
. The battery ceIl. embodiments shown in Figs. 4, 5 and 6 all opex.ate in the same manner as the battery cells disclosad in the pre~iously ment~oned U.'S. prior art, but are distinctive 20 from ~uch known cells in the fact ,that no tubesheet as such is requir.ed in the'present embodiments. due to the ~using of the individual hollow fibers.or. capillary tubes together adjacent.their open ends with the same glass as the ~ibers so as to~seal off the interstic.ie~ therebetween without . producing. deleterious expansion mismatch, and ~urther by the fa~t:that the anode chamber. is. exter,ior to the bundled open-ended hollow flbers,.rat~er than inkeriorly ther.eof as , disclosea by such prior art.de~.ices.. The embodiments shown in Figs. 4,:5 and 6 are'also. ~istinctive rom the cells 30 sho.wn in.the'pre~iously menti.oned p.ublished U.K. patent application in that the hollow interiors of the ~.ibers in ~7~

the present embodiments are ln open communication with each other and the cathode chamber thsough their open ends which ~
are surrounded solely about their outer wall surfaces with a ; --sealing mass forming a portion of the electrolyte/separator ,~
"
between the cathode and anode chambers. Further, contact portions of the longitudinal extent of adjacent fibers -~
beyond the sealing mass are sealed together to form a struc-turally sound fiber bundle, and the open ended fibers eliminates the need for a plurality of minute glass-to-metal seals in ) critical areas as required by the U.K. appll¢ation.
In operation of the battery cells of the present inven-tion, as current is dxawn from the battery the molten alkali metal anode gives up elect~ons and foxms the corresponding ; metal ions. The electrons go through an external circuit doing work while ~heir resultant alkali metal ions diffuse or otherwise are transported through the thin wall elec-trolyte/separator 10 and migrate toward the cathode. At the molten cathode, electrons are ed into the cathode chamber through the cathode lead from the external circuit foxming anions with the molten cathode material, for example sulfur.
These anions are, in effect, neutrali2ed by reaction with the alkali metal ions migxating through the electrolyte/
sepaxator bundle 10 thereby fQxming the alkali metal salt.
This reaction continues through the discharge cycle of the battery.
To ~echarge the battery, a source of current is attached to the leads so as to feed electrons through the anode lead to the m~lten sodium anode and the positive lead from the power source is attached to the cathode lead of the battery.
As the voltage of the power source is increased over the battery voltage, the exact reverse of the electrode reaction 7~
presented for the discharge cycle takes place. That is, alkali metal ions pass through the separator (bundle 10), and alk~li metal is regenerated and the reduced cat~ode material is oxîdized to its original state. An unexpected advantage of the present system particularly when utiliz~ng the sodium-sodium sulfide sulfur electrodes, over that achie~able wîth conventional lead-acid storage batteries, ~s that much more rapid rec~arging of the battery can be carried out without any ad~erse affects.
Referring no~ to Fîg. 7, a further em~odiment of a battery cell is shown having t~e anolyte exteriorly o the capillary tubes forming the electrolyte~separator and the catholyte interiorly of such tu~es, which facilitates increased circulation of the catholyte within the capillaries or hollow interiors of the electrolyte tubes. The battery cell 33a is formed o~ a composite glass or glass-ceramic housing 335 which incLudes an inner cathode housing 336 for cathode cham~er 332 surrounded by an outer anode housing 334 forming anode cham~er 328. In this embodiment the separator bundle or electrolyte 310 i~ in the form of a plurality of loo~ely packed hollo~ fibers or capillary tubes 312 having open spaces or interstices 316 therebe~ween. T~e longitudi-nal extent of open spaces 316 ~etween the capillary tu~es 312 are closed-of~ by being fused or sealed toget~er ~nto a solid sealing mass 3Z6 at each end of the tubes 312. The hollow interior 322 of eac~ of t~e tubes 312 extends completely therethrough and has opposed open end portions 320. A
suita~le cathode current collector 324, such as protecti~ely coated aluminum wire, extends throug~ each of said hollow interiors 322 and such wires are joined together at their ends by common electrode connectors 342. A suitable cat~ode ~57~

.
lead 344 extends outwardly of t~e cell 330 for connecting the same to an external electrîcal circuit.
It will ~e appreciated that all schematic representa- -~
tions of the hollow fi~ers or capillary tubes are greatly enlarged for purposes of illustration, since the diameter of the tu~es per se may be in the range of about 0.003" to 0.1"
and may have wall thicknesses of only about 0.0005", and thus it can be seen that thermal circulation or flo~r of t~e catholyte within the hollo~ fi~ers or capillary tubes could be some~at restricted. Thus, in order to facilitate such flow, should ît ~e desired, the cell 33a includes a recircu-lating tube 329 connecting an upper portion 331 of the cathode chamber 332 with a lower portîon 333 of satd cat~ode chamber, so that a catholyte 340 may readLly flo~ through the hollo~r interiors 322 of capillary tubes 312 and recir-culate through tube 329 as a result of temperature dependent density varîation wîthin tEle cell, or actual pumping. The anolyte 338 within anode cElamE~er 328 flows about the outer walls of the loosely nestled and centrally unconnected capillary tubes 312. Solid sealing masseæ 326, sealing the open spaces 316 bet~een the tuhes at opposite ends thereof, function to separate the anolyte which flo~s about the outer walls of the tu}:es from the catholyte whl'c~L flows t~rough the hollo~lr interiors thereof. An anode lead 348 extends outwardly from the anode c~mher for connection w~th an external electrical circu~t. The ~attery cell 33~ functions in the same manner as ~attery cells 30, 130 and 23a as set forth hereinbefore, and sets forth a further embodiment wherein the anolyte i5 located exter~orly of the capillary tul~es and the catholyte interiorly thereof, which is the reverse of the conventional sodium sulfur battery.

~ ~7~5 While various methods may ~e utîlized to form the separator bundle 10 of the present invention, the presently preferred methods are shown in Figs. l, 2 and 8-13. In the em~odiment shown in Figs. 1 and 2, a plural~ty of hollow fibers or capillary tubes are init~ally sealed off at one end, such as by flame sealing, like t~e closed end of a test tube. The sealed off capillary tubes are then stacked or nested into a ~undle and are sealed together along contact portions through the use of heat and slîght pressure. The sealing which is affected along portions of the length of each fiber or capillary tu~e need not be continuous, but should ~e strong enough to give the separator bundle suffi-cient mechanical integrity to not only withstand su~sequent handling ~ut also normal operational a~use. Tha unsealed or open end of the ~undle îs then flash heated to seal off the spaces or interstices ~etween the hollow fihers adjacent the open ends so as to form a solid sealing mass about the outer walls of the fibers while maintaining the open ends thereof.
The open face of the ~undle may be ground flat prior to the sealing off of the interstîces and, if desired, powdered glass of the same compositîon as the fibers may be provided within the interstices to ~acilitate t~e sealing off thereo.
The electrode collector utilized ~ithin the hollow interiors of the fi~er~ or capillary tu~es is preerably formed of a plurality of alum~num wires hav~ng a protective coating such as moly~denum disulfide w~ich are inserted within the open ends of such tubes. One method of insexting such wires is sho~n in Fîg. 8 wherein a separator bundle 1 is positioned within a container 80 ~ith the closed or sealed ends 18 of the- fi~ers or tu~es 12 at the ~ottom and the open ends 2 a at t~e top. A plural~ty of precut protectively ' '`` 1~S7~5 coated aluminum wires havin~ a. dia,meter slightly lar.ger than 1/2 the inside diameter. of th.e h~llow interior o~ the tubes.
12 are placed as a loose bundle of al~uminum wires, 24 o~er the separator bundle 10. The:contai~er 80 is then .uibrated in.a.vertical direction causing a sing.le wire 24. to ~all into the hollow inte~ior 22 of. each: ~ibe~, or capillary tube 12 thr.ougk:its open end.2Q.
In view of tke problems:which.may be encounter.ed in.
positioning the aluminum wires: within.tke intexiors o~ the capill-ary tubes, a further emb.odiment is shown in ~ig. 9.
wherein.the.current collector wire.24.is inserte.d ~ithin the hollow inter.ior 22 while'the hollo~ fiber or capillary tube 12 is being. drawn. A smal1: ~eLlo orifice.82 is sho.wn ha~ing molten glass 83 flowing downwardly ab.out a standard beI.l 84 havi~g.the alumin~m wire.24 f.ed downwardly therethr.ough with air or inert gas represented by ~rrows 85 utilized to main-tain.the hollow interior.
Altho.ugh the temperatures. of the molten glass 83 flowing thro.ugh the orif.ice is relativeIy high compared to the meIti~g po.int of aluminum,. the aluminum wire would be traveLing at a rate .suff.icient to :avoid.overheating and may even .function to supply beneficial internal cooling in the forming 20ne. The thus ~ormed.tub.ing with the aluminum wire therein l~.~collected upon a suitabLe winding reel and the friction exer.ted between the wire and the inside diameter of the'c~pillary tube would b~ suff.icient to pull the wixe thr.ough:the beI.l or air tube 84 during forming. The thus formed c~pillary tube ~ith the wire therein i5 then cut to ' desired len~ths and each fiber. or capillary tube 12, as .30 sho.wn in Fig. 10,. is po~itioned at an inclined angle at a given distance from a ~to.p surface 86. Accordingly, the 7~
wire 24 retained within the ~ollow înterior 22 of t~e tube 12 slides outwardly through the opened end 20 into stop abutment with the stop surface 86 and the wire cut at a predetermined location noted ~y cutting arrows 87. Simul-taneously, a burner 88 flame seals the opposite end into a closed or sealed off end 18 similar to t~e closed end of a test tu~e.
After cutting t~e collector wîre 24 to desired length and sealing the end 18 of each capillary tube 12, t~e fi~er or tube is tilted ~ackwardly as shown in Fig. 11 so that t~e collector ~ire 24 slides downwardly wit~in t~e hollo~ interior 22 toward the closed or sealed off end 18. A plurality of ; suc~ fibers containing the shortened wires are t~en nested and sealed toget~er along their contact areas ~hile retained in a closed-end-down position and the upper open end 20 of the resulting ~undle 10 of fiber 12 could be ground flat if desired and the interstices between ad;acent tubes flash i fired and sealed together to form a solid sealing mass 26 without affecting the open ends or t~e collector wires restîng adjacent the lower sealed ends 18 of the tu~es. T~e ~undle 1~ is then positioned as shown in Fig. 12 at a given distance from a stop surface 86 so that t~e collector wires 24 31îde outwardly of open ends 2a and abut against the stop surface, where upon the outer ends of such ~ires are cr~mped toget~er to form a common electrode connector 42.
As a further alternative as s~own in Fig. 13, a large ~undle lla of reIatlvely large diameter hollo~ fibers or capillary t~bes 112 are fused together and reheated and redrawn through a redra~ furnace 89 and attenuated ~y suit-a~le rollers g~ into a f'nal ~undle lQ of ~ollo~ fibers orcapillary tu~es 12 of des~red diameter. For example, the . tubes 112 may have a diameter of about .1" and a w~11 thick- . ness of about .006n, whereas the cap~llary fibers of bundle 10 may have ~ diameter OL about .01" and a wall thickness of about .00.06". T~e drawn bundle 10 is cut into desired lengths, one end sealed, and the current collector wires 24 inser.ted in a manner such as shown in Fig. 8. As an alterna-tive, the aluminum wire could be inserted through each of the tubes 112 from reels prior to being redrawn and fixed to - t~e lower end of bundle llQ, and the~ unwound from the ~arious r.eeIs as the bundle 110 is being elongated. Further, if des:ired, a single relatively lar.ge hollow blank could be prouided with a central wire:means and redrawn down t~
desired fiber size while feeding the wire therethrough.
: Although I have disclosed the now preferred embodi~ents of my in~ention, it will be appreciated that ~arious changes and modif.icati.ons may be made thereto without departi~g from the spirit and sco.pe thereof as def.ined in the appended clalms.

Claims

I CLAIM:

1. A battery cell for generating electrical energy which comprises, container means having anode and cathode chambers, said anode and cathode chambers being separated by a combina-tion electrolyte/separator, said electrolyte/separator being in the form of a bundle of hollow fibers having inner and outer surfaces positioned substantially parallel to one another along their longitudinal extent, the interiors of said hollow fibers being open at one end of said separator bundle and sealed closed at the opposite end thereof, said hollow fibers forming said separator bundle having interstices formed along their outer longitudinal surfaces between adjacent hollow fibers, wall portions of adjacent hollow fibers forming said separator bundle being sealed together adjacent the open end thereof forming a solid sealing mass of the same composition as said hollow fibers closing off the interstices between said hollow fibers adjacent their open ends, the outer surfaces of said hollow fibers extending into one of said chambers with the interior of said hollow fibers being closed off therefrom by said sealed ends, the inner surfaces of said hollow fibers being in open communic-ation with each other and the other chamber with the open ends of such hollow fibers opening into said other chamber, an anolyte communicating with one surface of said separator bundle, a catholyte communicating with an opposite surface of said separator bundle, longitudinally extending cathodic current collecting means within said container means extend-ing substantially along the length of said hollow fibers and surrounded over a major position of its extent by said catholyte, and anodic current collecting means.

2. A battery cell for generating electric energy as defined in claim 1 wherein adjacent hollow fibers within said bundle have longitudinally extending contacting outer surface portions, and said contacting outer surface portions being sealed together beyond said solid sealing mass at least along a portion of their longitudinal extent.

3. A battery for generating electric energy as defined in claim 1 wherein said hollow fibers are formed of a glass or glass-ceramic material and said solid sealing mass, in conjunction with said hollow fibers separating said anode and cathode chambers, being of the same composition as said hollow fibers.

4. A battery cell for generating electrical energy as defined in claim 1 wherein said cathodic current collecting means includes a plurality of wires extending longitudinally along the substantial. extent of the interiors of said hollow fibers, and extending outwardly through the open ends thereof.

5. A battery cell for generating electrical energy as defined in claim 4 wherein one said wire is positioned within and extends substantially along the interior of each hollow fiber, and said wires are joined together in said cathode chamber.

6. A battery cell for generating electrical energy as defined in claim 4 wherein said cathodic current collecting means is in the form of a plurality of protectively coated aluminum wires.

7. A battery cell for generating electrical energy as defined in claims 1 or 2 wherein the outer surfaces of said hollow fibers extend into said anode chamber, and the inner surfaces of said fibers are in open communication with said cathode chamber.

8. A battery cell for generating electrical energy as defined in claim 1 wherein said anolyte is within said anode chamber about the outer surfaces of said hollow fibers and within the interstices formed between adjacent fibers, and said catholyte is within the hollow interiors of said hollow fibers forming said separator bundle, which interiors are open to said cathode chamber.

9. A battery cell for generating electrical energy as defined in claim 8 wherein said cathodic current collecting means includes a plurality of wires with one such wire being longitudinally positioned within the hollow interior of each fiber forming said separator bundle and extending outwardly through the open end thereof, and each. said wire being surrounded with the catholyte being retained within the interior of such hollow fiber.

10. A battery cell for generating electrical energy as defined in claim 1 wherein said container means includes an anode housing enclosing said anode chamber and a cathode housing enclosing said cathode chamber, said housings being. vertically positioned with respect to one another, means sealing said housings together in a fluid tight relationship, and said solid sealing mass being sealed about its periphery to an inner surface of one of said housings substantially at the same vertical elevation within said container means at which said sealing means seals said housings together.

11. A battery cell for generating electrical energy as defined in claim 10 wherein said cathode housing has a hollow interior and a major portion of said anode housing is positioned within said hollow interior such that the upper surface of the catholyte within said cathode housing is above the vertical extent of said hollow fibers forming said separator bundle.

12. A battery cell for generating electrical energy as defined in claim 1 wherein said container means includes an anode housing and a cathode housing said solid sealing mass being sealed in an opening to said anode housing and separa-tes said anode chamber from said cathode chamber, and the interiors of said hollow fiber being in open communication with each other and said cathode chamber through said open ends.

13. A battery cell for generating electrical energy which comprises, container means having anode and cathode chambers wherein the anode and cathode chambers are separated by a combination electrolyte/separator, said electrolyte/separator being in the form of a loosely packed bundle of hollow fibers having inner and outer surfaces positioned substantially parallel to one another along their longitudinal. extent, the interiors of said hollow fibers being open at both ends of said separator bundle, said hollow fibers forming said separator bundle having interstices formed along their outer longitudinal surfaces between adjacent fibers, wall portions of adjacent fibers forming said separator bundle being sealed together adjacent the open ends thereof forming a solid sealing mass of the same composition as said fibers and closing off the interstices between said fibers adjacent their open ends, the outer surfaces of said hollow fibers intermediate said solid sealing masses extending within one of said chambers with the interior of said fibers being closed off therefrom by said solid sealing masses, the inner surfaces of said fibers being in open communication with the other chamber and with the open ends of such fibers opening into separated portions of said other chamber, an anolyte within said anode chamber and communicating with one surface of said separator bundle, a catholyte within said cathode chamber and communicating with an opposite surface of said separator bundle, and longitudinally extending cathodic current collecting means within said container means extend-ing substantially along the length of said hollow fibers and surrounded over a major portion by said catholyte.

14. A battery cell for generating electrical energy as defined in claim 13 wherein said hollow fibers are formed of a glass or glass-ceramic material and the solid sealing masses at each open end thereof which separate. the anode and cathode chambers are formed of the same composition as said hollow fibers.

15. A battery cell for generating electrical energy as defined in claim 13 wherein said cathodic current collecting means includes a plurality of wires extending through the interiors of said hollow fibers.

16. A battery cell for generating electrical energy as defined in claim 15 wherein a protectively coated aluminum wire extends through the interior of each of the hollow fibers forming said separator bundle, and said aluminum wires being connected together into a common electrode connector.

17. A battery cell for generating electrical energy as defined in claim 13 wherein the outside surface of said hollow fibers extends within said anode chamber and an anolyte flows through the interstices formed along the outer longitudinal surfaces between adjacent fibers, and the inner surfaces of said fibers being in open communication with separated portions of said cathode chamber.

18. A battery cell for generating electrical energy as defined in claim 17 wherein a conduit communicates between said separated portions of said cathode chamber and a catholyte circulates through said conduit and through the interiors of said hollow fibers which are in open communi-cation with said separated portions of said cathode chamber.

19. A method of making a battery cell having a first oxidizable liquid metal electrode, a second fluid reducible electrode and a substantially fluid tight electrolyte/
separator separating said first and second electrodes wherein said electrolyte/separator is in the form of a plurality of hollow fibers which comprises, forming a plurality of a longitudinally extending hollow fibers having open ends, sealing off one. end of. each of said hollow fibers, forming a bundle of said hollow fibers by juxtaposi-tioning a plurality of said hollow fibers in substantially parallel relationship with longitudinally extending outer surface portions of adjacent hollow fibers contacting one another and with said sealed ends of said hollow fibers being positioned at one end of said bundle and opposite open ends of said fibers being positioned at the opposite end of said bundle sealing at least a portion of the contacting longitudinally extending outer. surface portions of adjacent hollow fibers together to form a substantially rigid separator bundle with interstices formed between adjacent fibers along their outer longitudinal surfaces, sealing wall portions of adjacent fibers forming said separator bundle together adjacent the open ends of said. fibers and forming a solid sealing mass of the same composition as said fibers and thus closing off the interstices between said fibers adjacent their open ends, positioning current collecting means within said fibers so as to extend outwardly therefrom through said open ends, and sealing said separator bundle within a battery cell housing with said solid sealing mass positioned substan-tially at an interface between said first and second electrodes.

20. A method of making a battery cell as defined in claim 19 including the step of positioning a current collector wire within each of said hollow fibers, and joining said current collecting wires into a common electrode connector.

21. A method of making a battery cell as defined in claim 19 wherein said separator bundle is positioned within a container, a bundle comprising a plurality of loose aluminum wires. having a diameter larger than one half of the inside diameter of said hollow fibers is positioned above the open end of said separator bundle, and said container is vibrated so as to position one aluminum wire within each of said hollow fibers.

22. A method of making a battery cell as defined in claim 19 wherein said plurality of longitudinally extending hollow fibers are formed of a glass or glass-ceramic mate-rial.

23. A method of making a battery cell as defined in claim 22 wherein said plurality of longitudinally extending hollow fibers are drawn from molten glass with a current collecting wire drawn centrally within the fiber. simul-taneously with its formation.

24. A method of making a battery cell as defined in claim 23 including the steps of cutting such drawn fiber into desired lengths, inclining such lengths to the horizontal at a desired position from a stop surface, sealing the inclined end of each such fiber. abutting the current collecting wire within each such inclined fiber against said stop surface and cutting said wire at a predetermined location, forming a bundle of said cut and end-sealed fibers with the sealed end downwardly, and inclining said bundle at a predetermined distance from a stop surface with the sealed ends upwardly, and joining together current collector wires from said fibers abutting said stop surface to form a common electrode connector.

25. A method of making a battery. cell as defined in claim 19 wherein said substantially rigid separator bundle is formed by fusing together a plurality of relatively larger diameter tubing to form a first relatively larger size bundle, heating and redrawing said relatively larger size bundle of relatively larger diameter tubing so as to attenuate such tubing and said bundle into a drawn bundle of relatively smaller size formed of hollow fibers of desired minimal diameter.

26. A method of making a battery cell as defined in claim 25 including the step supplying each relatively larger diameter tubing with a current collecting wire interiorly thereof and redrawing such tubing about said wires. into a drawn bundle of relatively smaller size hollow fibers having a current collecting wire within each said hollow fiber.

27. A method of making a battery cell as defined in claim 19 including the step of supplying particles of glass of the same composition as said fibers within the interstices adjacent said open ends to facilitate the formation of said solid sealing mass and the sealing off of said interstices.

28. A battery cell for generating electrical energy as defined in claim 2 wherein said cathodic current collecting means includes a plurality of wires extending longitudinally along the substantial extent of the interiors of said hollow fibers, and extending outwardly through the open ends thereof.

29. A battery cell for generating electrical energy as defined in claim 2 wherein said anolyte is within said anode chamber about the outer surfaces of said hollow fibers and within the interstices formed between adjacent fibers, and said catholyte is within the hollow interiors of said hollow fibers forming said separator bundle, which interiors are open to said cathode chamber.

30. A battery cell for generating electrical energy as defined in claim 2 wherein said container means includes an anode housing enclosing said anode chamber and a cathode housing enclosing said cathode chamber, said housings being vertically positioned with respect to one another, means sealing said housings together in a fluid tight relationship, and said solid sealing mass being sealed about its periphery to an inner surface of one of said housings substantially at the same vertical elevation within said container means at which said sealing means seals said housings together.