GB2207545A

GB2207545A - Glass seal for sodium-sulphur cells

Info

Publication number: GB2207545A
Application number: GB08717859A
Authority: GB
Inventors: Walter George Budgen; Peter Raymond Smith
Original assignee: Lilliwyte SA
Current assignee: Lilliwyte SA
Priority date: 1987-07-28
Filing date: 1987-07-28
Publication date: 1989-02-01
Also published as: ZA884595B; GB8717859D0; FR2618948A1; JPS6454672A; DE3822733A1

Description

-I- "ELEC'I'ROCIIEI.IICAL CELL" 2 2 0 7 5 4 5 THIS INVENTION relates; to

ill elect rochem i ca 1 cell. blo re particularly the invention relates to the seal.ing of alpha-alullfilla to beta-alumina in an electrochemical cell.

According to the invention there is provided a. methud of sea.ling an a.lpiia-altiviiiiii compunent to a bet-,i-.,ilx-uitji)a component in an electrocheifical cell, which method comprises using a high-holate horosi Ii cate g ta s s to., c a 1 the a.11)1i,-i-alLuit.i na componelit to tile 1)eta-altuiiiiia component, the glass comprising EI- 25% hy inass 11, 2 () 3 and 056- 75% by mass SiO2, the major proportion by mass of the halance comprising At 2 () 3 and alkali metal oxide, and the glass coliti)y. isjjig at Illost 1% by mass alkalille Cal-th illet.11 oxides.

is I lie B 2 () 3 content of the glass is prefelably 12-20% hy. mass, wore preferably 14-17% hy mass. The SiO 2 content ill tum is prelerahly 66-73% by mass, more preferahly67-70% hy mass. 1he glass may comprise 3-8% by mass AI 2 0,,, preferably 5-7% by wass. The alkali metal oxide may be essentially Na,O, wid nily forlit 5-10% by mass of the glts..:;, ptelerably 7-8% by imiss. Ihe alkaline earth metal. oxide content of the glass is 1 1 preferably less thall (),.S% by mass, more preferably less thall 0,310- by mass. The glass may comprise 1-3% by mass ZW.

The ApplicaiA has fowid that a stiltable glass for tise ill the method of the presetit iiiveiiljoii is a high-burate borosilicate glass.ivailable wider the tiade wark SCRY1T from Schott Glaswerke. ai 1 lz z M' Germany, as Type No. 8245. This glass has the followhig composition oil a mass basis, as determined by X-ray fluorescence:

1 0 Col is t j tuel 1 t lli-opurtoii 1Ly Mass B 2 () 3 1596 SW 2 69,8 AI ( ") 3 5,4 2 is BaO less thaii 0,1 CaO less thall 091 higo 11.11 K 2 less tliall OY I Z110 M1 Na 2 0 7,2 I he inveinkin extends to a lie vinet i c sea 1 all all)li.i-,ilttiiii iia coini)oiieiit wid a 1)eti-altutjjiii coiiil)otieiiL ill all electrodiewical cell., which comprises a glass as described above.

The invention extends also to an elecirocliciiiic..il cell which comprises all all)lti-alttiniii.t coiiil)oiieilt iiid a 1)eta-altuitijla (:oiiil)oiici)t, which coinpoiieiits are sealed together by me.mis of a glass as described above.

R 4 Ill such cell, the all)li-.i-aiiiiiiiiia component way he a ring of scaled to the illouth of a tube constituting 1 fie lict,i-altiiiiiii,i component, the cell having a housing scaled 1 o tile.

The cell Illay have a sodium anode, and may bc a cel 1.

Instead, it Allay have a Soditun anode andp ill itt; state, a cathode which Comprises as its active Cathode 111ater-i'll a trail.sition metal selected from the group comprising Fe, Nj, Cv., Cu, bbx and mixtures thereof, or a compound of at least one said tlansition metal. with one or more numbers of the group comprising carbuil, Ililloge'll, boron, si.L.icoii and phosphorous, Ihe active cathode material being dispersed ill.ill electrol).te-1)eritic.it.)le elearonically conductive povous cathode matrix impregilated by a sodium moiten sait electrolyte and having sodium chloride dispersed therein ill 1),.iilictil. tte fonn. Such t rans j t i oil metal-based active cathode ma t e A. ia 1 s 1 re chlorinated upon charging, to the corresponding Ibus, ill Ow.

case of metallic cathode materials, the chlorides are eg NiCl.)q cr(C1 cocl or b[A1C1 In such cells, the housing way be of a metal whi ch is at least as noble as the transition welal of the cItlio(](?, and thi s housing, and a inetal clostire for the mouth of' the tube, ma). be sealed. to the jli)lii-altuiiiiii component, eg by therinucompression bonding or by sealing by ineans of' the glass above.

The actual scalivig of the Colllpollellt to the 1)eta-aliniiiiia coilil)c)iieiit caii be effected iii any coiivejijeiit lcjiowil lashion.

Thus the glass may be employed as a powder, or as a prefonii such as a glass ring, introduced between the respective surfaces of all)lti-.. jltllllilla and 1)eta-altuitjii-,i to be sealed together. lit each case the glass will he fused, lienitetically to seal the ' coiltl)olieiits together; mid simi lar procedures may be followed to seal the alpha-alumina compollellt. to tile casing and tube closure by means of g la -S s.

The invention will iiow be described, by way of example, with reference to the accoiiii),-iiiyiiig diigrwtuiiatic di-nwiiigs, inwliicll; Figure Ishows a schematic sectional side elevatiou ol. ail elect roclicillical cell according to the inveiftion; Figure 2 shows a detail of the seal between the alpia-allmiinl rinq mid the beta-alimiina tube of an alternative construction for the eel.]- nF Figure 1.

Iii the drawflig, refermce immeral 10 gemi-ally desigmites an elect roclieitti cal cell in accordance with the iiiveiitioti. The cell is shown broken midway aloiig its lejigtli, typically lx,.iviiig aix oxitside diameter (if about 30-70 111111 and a letigtix of about 200-600 mmi. The cell showii has i molteil soditnii active amde material 12, a sodituit aluminium chloride molteil salt electrolyte 14 mid a cathode 10 which is illmlersed in the electrolyte 111 and in its charged state comprises aii electi-olyte-1)erliie,.il,)le porous iroil inatrix which is el-ec.i.i. oiijcilly conductive and contaiiis l:e/FeCI, in dispersed fonfl therein as its active cathode sul),-,t,-iiice. The matrix of the cathode 1.6 is saturated with the electrolyte 14 and has sufficietit. finely divided NaCH dispersed therein to eiisure that, in all states of charge of the active cathode stil)stiitce, the electrolyte 14 is stojclijoiiietrical.ly exact M&AICIA.

Tlie cell 10 lias a ifild steel outer easing 19 li.Aviiig a 1)ase ú10 for supporting it ill all upright attitude as shown. The casing 19 is sealed to an annular ali)iii-altuxiiiia insulating ring 22. An opell elided beta-altuixiiia separator tube 24 is located concentrically within tile casing 18, the lower end of the tube 24 being closed and the upper or open end of the tube '414 being glass-sealed to the ring 22 in sealing fashion. In this regard it will he hoted that. the i,ji)g is rectangular in radial cross-section, and oil its axially inner lace. i.e. its lower or inside face as shown in the drawing, it has a circumferential groove 25 in which the rim of the open end of the tube 24 is received, and in vAlich said rim is sealed by nleans of said glass '1'y No. 8425. Instead, said rim may be sealed by said 91-ass, into a circuiiferential rebate fornled along the radially inner edge of said face of the ring 22, eg by means of counterboring the ring 22, as shown in the detail of Figure 2. 'llie "n end of the tube is closed by a closure disc 26 sealed by a glass to the radially inner surface 20 of the alplia-alunina ring 22. An anode terminal post 28 is welded to tile easing 18, uid a cathode teilitinal post.30 passes titiougli a sealed central opening in the disc 26, downwardly into the electrolyte 14. The lower portion of the post 30 is embedded ill and ill clect.t-oiijc contact with the matrix of the cathode 10. Tlie watrix lets as 'I catilode current collector, while the housing 19 acts as the anode current collector. 'lliere is a gas space 32 above the anode material. 12, and i gas space 31 above the electrolyte 14. The cell is shown connected to,in external circuit by electrical leads 36, 38 cojuiected respectively to posts 28, 30.

The sinice between the easing 18 and tube 2,1, occulAed 1)y tile anode sudiLuit 12, fonns an anode compartment, and the interjor of tile tube 24 fonits a cathode coiiii)ai,tiixe.iit. These coiiil)artiticiits aie from each other by the separator tube 24, and by sealing of the ttll)e 211, casing 18 and disc 20 to the -iliilia-alt-uiiiiia ring 22, the cashig J8 similarly being sealed to the radjally outer surface of the rijig 22 by a glass.

The overall. charge/discharge reaction of the cell caii be relwesented by the reaction:

charge 2 discharge is 2NaCI + Fe Accordiiigly, sodium 1)asses from the atiode c(iiiii),ii,tiiielit 1.o tile cathode comixirtment durbig discharging, through the 24; mid it passes ill the olil)osite direction during charging.

Ihe AI)I)Iicaiit Im.s found fliat said glass TY1)e No. 8245 high-borate 1)oro..;jlicate glass lirovides excellent sealjiig of the cell, particularly of the i-ii)g 2Z to the separator 24, ill heinetic f. nsllioii, and is resistant to thennal shock at the operating temperature of the cell (200-350"(,) and chemically resistalit. to the cell eiiviiolltlleiit, particularly the molten sodi.uiii and the sodium aluminium chloride. Glasses that resist corrosion by molten soclitim do not necessarily withstand sodium aluminium chloride.

Claims

1. A method of sealing an tlplta-altuixiiia component to a bet,ialtniiiiia component in m electrochernical cell, which method compri ses using a high-horate borosi 1A cate gl.,tss to sc, t 1 the alpit.ialiniiiiia component to the 1)eta-,iltutijiia coivq)oiieiit, the glass comprising 10- 25% by miss B 2 () 3 and 65%- 75% by mass Sio 29 the major proportion by mass of the balance comprising AI 2 () 3 and alkali metal oxide, and the glass comprising at most 1% by mass alkaline eart.h Inet. al oxides.

2. A method as cl,-,tjuied in claim 1, in which the B, () 3 Content, of the glass is 1-2 - 20% by mass, the SiO 2 content of the glass is 6r)-73% by mass, the AI 2 () 3 content of the glass is 3-8111 hy wass, the alkali metal oxide in the glass is essentially Na 2 0 and the alkaline carth metal content of the glass is less then 0,5% by mass.

3. A method as claimed in claim 2, in which the B 2 () 3 Content of the glass is 14-1.7% by mass, the SJO 2 content of the glass is C,77(Ioi-, by 111(15s, the AI 2 0 3 content of the glass is 5-7% by mass, the Na z 0 Collient of the glass is 5-10% by mass, and the alkaline earth metal oxide cOlltellt Of tile glasS, is lesS, til,)" 0,3% bY 11Oss.

A method as claimed in claivit 3, in which the glass is glass Type No. 82, 15 obtained fl.olit Scilott Glaswerke.

5. A method of selling.111 all)ll,]--,lltullilla collll)()llel)t to.1 1)et.i-altuiiiii.i component in an electrochemical cell, substwitjally as described herein.

6. A liennetic seal between an component and 'I beta-altunina component in an elect rochem i ca 1 cell, whi ch sea 1 i S a high-borate borosilicate glass comprising JO-25% by inass B 2 0 3 and 65- 75%, by mass Sio 2 the mijor proportion by mass of the balance comprising A.1 2 () 3 - and alkali inetal oxide, and the glass comprising at most. 110 by mass alkaline eartlx metal oxides.

7. A seal as clainxed in claim 6, in which the glass is glass Type No. 8245 obtained from Schott Glaswerke.

S. hi elect rochemi ca 1 cell which conprises an component and a 1)et,-i-llttiiiiiit component scaled tollether by menns of a glass, which is a high-borate borosilicale glass comprising 10-2510 by mass B 0 and 65-75% b). mass SW,, the major proportion by 111ass of tile 2 3 11 balance comprising AI 70 and alkali met.al oxide, ind the glass k. 3 comprising at most 1% by mass alkaline earth metal oxides.

9. A cell as clainted in claim 9, in which the cunponent is a ring (if and iq sealed to the mout-11 of' a tube which constitutes the 1)et.i-aluiiiiii.,i component, the cell having a housing sealed to the ring.

i 9 - A cell as claimed in. claim 9, which has a s(Kiiinn atunip, nib!, in its discharged state, a cathode which comprises as its active cathode material, a transition metal selected from the giuup conTrising 0, Mi Cr; Co, lch and mixtures of said transition metals, or comMnnupi ol at le,i,; t one said trnnsition metal with (.)lie or more iit(,iiil)cis ot tll(' gloup comprising carbon, nitrogen, boron, silicon and phosphorous.

1 11. Ail electruchemical cell substantially as descrilled and as itlustrated herein with rerprence to the accompanying drawing.

Publish id 1988 at The Patent Onfice, State House, 4E6 71 High Holborn. London WC1R 4TP. Ptirther nopies may be obta4ned from The Patent Office.

Sales Branch, St irary Cray. 0.-png,,,-. Kent LR:5 3RD Printed by Mult tiplex techrjq,.,es; ltd. St Mary Cray, Kent Con 187