Note: Descriptions are shown in the official language in which they were submitted.
3~L
SY~ [F':[CArr`ION
The inventiorl relates to a lead storage batLery hav:irlg
a sllpply o:f expander material located wi.thill the electrolyte,
:Erom ~h:ich the expander is resuppli.ed durillg at le~ast a portion
oE the :I-i.Ee o:E the storage battery.
Fxpallder add:itives to the negat:ive acti.ve mass are
:i.nt:ende(l to counteract the formation oE compact lead crysta:Ls
by inLerferillg wi.th :lead sepa:rat-ion during charg:ing, and
thereby to mainta:in the highly porous s-tructure o:E the elec~trode
p].ate~s. Suita~le expander materials are ba:riurll sulphate,
high molec.ular organic substances, particu:larly l:i.gnin
derivatives, or coloring materials such alizarirl .red :Erom
the ser-.ies of hydroxyanthraquinolles.
~ ccclLIse the expander materials have si.gni.ficant solubili~y
:Ln su~l.phur:ic acicl, there takes place a progressive leaching
out of thc negative e].ectrodes, with the expander also reaching
the positive e:Lectrodes in the course oI cyclical operation,
where it is destroyed through oxldation. The consequellce
o~ this loss of expander is a decrease in capacity andl :Eor
starter batter:i.es, particularly a reduction in their performance
in cv:Ld starts. The use of h:i.g}ler initia:L expandeI quantit:i.es
in the rllass c:ompos; tions has been of on].y lim:itetl remedia:L
e~:fect for this short:com:ing because -this increased in:itial
concentration was accompanied by a spreading ef:Lect in the
ear:Ly stages of the storage battery liEe which substantiaLly
exceeded the degree necessary in order to ach:ieve a predetermined
currerlt: de'Live:ry capability.
-2--
In accordance w:itll German Patent :l~uh:L:i.cclt:ion ~O.E~enle--
gllrlgssc~lrift) ~,~55,3:1.3 it. Ilas there:Eore a1.rea(ly heen propose(l
io store expander rnater:ial in 1 vessel. whic}l is in commuTl:icatio
w:i.th the aci d electrolyte through a small Opell:ing, SO that
thcre ta~es place delivery o:E expander contirluousl.y, as a
furlctiorl of the cross-section of the opening, the satl1ration
concerl~-ratio!l, and the difEusi.on coef:Eic-ients, over an exterl(led
period o:E time. 'l'he drawback o.E this ar:rangmenl: is that the
delivery o:[ spreader mater:i.al from the storage starts as soon
as the cel.:L is .E:illed.with the acid. Due to this unrestricted
start of the addition of stored material to th~ normal delivery
of expander :Erom the negative p].ates theIe a:rises~;n over-
supp:ly, -in a manner sirnilar to that previous~l.y desc:ri.bed above.
'l'he reasorl i.s that, in a new storage battery ce:L:I.,
the quant:ity of spreader materlal in the negative mass is
:ini.tia:l:ly made su:Eficient for several. hundred cyc:Les.
~ ccordi.ngly, it is an object of the p:resent inventi.on
to provi de a storage arrangement for the ex~parlder m.ltcri.al
:in such a manner that .i.ts.consumption is llrevented at least
i.n the early stage of the storage battery l.:i.fe, and that it
is suppl:ied only Lrom a subsequent point in t:i.me, progressively,
an(l in accordance w:i.th the true need.
Th-i.s and other objects lhich wil]. ap~pecll^ are achieved
in ac(:ordance with thc! invention by separat.i.ng tlle expander
supply l.rom the elect3-olyte by a barr:ier materiLI~l., which disso:lves
s-Lowly in the electrolyte and li.berates the expander af-ter
a predc~l:ermi.nlbll~ ti.lile period~
7~3~
llpon the start o cycl:ical operation9 the barrier materiaL
:is perlllallently sllbjected to a corrosi.ve alternating attack
:in Lhe surrourlcl:ing, su.lphuric ac:id contain~ g n~edium. Th:is
mecl:i.um ~:irsL causes an oxidative decompos:itiorl of the barrier
nlater:ial, wh:ich initially p:~ovides an inperrneab:Le wal.l between
the spreader and the electro~yte. However, :i.t :is only aEter
a preclete:rminecl time that the inEluence o:E thc decompos:ing
:for.e- ,o welkens the barrier parti-ti.on that ;.t ruptures i.n
places, and the expander material which is there no ].onger
protectecl :is taicen up by -the su:Lphuric acid, oxid:izes, and
begins to dissol.ve. The conti.nuing destruction oE the wal:l
causes the resupply of expander material to both electrode
polar:it:i.es to continu~ steadily, so that good current loaù
capacity an(l mass uti.liYation are assured at least :Eor an
aclclitio~ l po:rtion of the storage battery l:i:Ee.
A suitab].e wall material for the expander supply embodying
the :invent:ion is Syntlletic pl.astic. Included7 fo:r this purpose,
are all synthetic resin products whicll have lim-ited resistance
to a sul.phuric acid medium, both pure po.Lymers~ as well as
co- or homo-polymers. These products may exh:ibit the most
varied degrees of corrosion resist:lnce, not only because of
the:ir chemical structure, but also because oE aclcl:it:i.ves o:E
softeners and stabiliY.ers, so that a user has a wide choice
with respect to a suitable wall materia:l..
As the principal parameter influencillg the corrosi.on
speed o:E a synthetic p].astic, there may be cons-iclered its
degree Or polymeri7ation. Tllils, a low po].ymcr:ic syTIthctic
.resin product clecomposes more~ rapidly than a high polymeric
~'7~
pro(lucL wiLh corresl)c)l-ldirlgly higll molecu:Lar we:ight. Unclc!r
the preva:i~ing circumstances, t}le decomyosit:i.on duration o.f
a p:Lastic, l~h:i.Ch o:E course also clepends uporl wall. thicl<ness,
CaTI vary from a few months to many years. ~xarnp:l.es of plast:ics
which are suital)le :For the invent:ion are: polyv:inylchloride,
polys~ Eonates, epoxy resins, po:l.yethyleneterephtllalate,
polybut~l.enetereplltllalate, polyethy]elle, polypropylelle, poly-
i.et::r~LIuoret}ly:l.erle, polytrifluo;-ochl.oroeL}Iy]er~e. Howevc~r,
th:is lisl::ing is not to be considered as e~clusi.ve.
Anotller sui.table wall material for the expander supply
embodying the invention may be a metal, beca~se its at-tack
hy corrosi.on proceeds relatively uniform:Ly and in a speci:Eic
manller. However, there are preferably selected such metals
as do not detrimenta:Lly influence the electrochemiccll per:Eormance
o:E -thè ceJ.l, e:ither at all, or to a neg:l.ig;b:Le extent. Particularly
des:irable :E:rom th:is standpoint within a lead storage battery
are lecLd, antimony, or tin, including b;.nary and ternary alloys
o:f these metals. An antimony membrane would hclve the add;tiollal
aclvantage that -l:he expander snpply secondari:l.y Eunctions as
an antimr-ny supply, sincr-~ the progressive dissolut;.on of tl-le
barrier wall causes antimony in the form of ant-imony conta:i.nillg
3-- and 5- valenced ani.ons (SbOSO~, [H5n 5Sbll5nl ) migrates
to the electrodes and advantageous]y inf]uences at least
the behav.ior o:E the posit:ive electrode. Th:is i.s because,
.i.f the electrode grids are of an antimony-f.ree al.loy, e.g.
lead ca].cillm, which is desi:rable because of high hydrogen
overpotelltia], t~lell exper~ience hcls sho~n that tllese positive
e:l.ecLrocles have a tendency toward increased cr~lrnb:l..ing, a
3~
d:isadv.l[~iag~ whic.h grid plates ~ith anti.rnc)ny---cc,nla-;rlirlg al].oy
gri c7~s clo not exh:i.b-it clue to suf'c'iciellt antimorly presellce in
the active positive mass.
Because, on the other hand, a posit:ive elect:rode
grid of a lead antimony alloy corrodes mLIch mor~ qlliclcly than
an arltirllony--free grid, positive e:lectrocles ~;th allt~ lony-Eree
gr i dC; Call be L~sed with unrestricted advantage, when the pos;tive
active mass :i~s supp:liead with antimony for prevent:ioll of
crurnb].illg not from the grid itself, but from the corroding
snp~ly barrier wall. This arrangement embodying t.he invetltion
is particularly desirable Lor storage batteries wh:ich are
s~lbjected to a strong cyclical Load, with occas:ional deep
cliscllarge, and which contain antirnony-free grid p~Lates.
