Improvements in and connected with Primary and Secondary Galvanic Elements.
Year: 1896

page_text: PROVISIONAL SPECIFICATION.
Improvements in and connected with Primary and Secondary
Galvanic Elements.
I, HENRY LEITNER, of 39, Elsasser Strasse of Berlin, Kingdom of Prussia,
Germany, chemist do hereby declare the nature of this invention to be as follows:-
This invention relates to primary and secondary elements of the kind in which the
electrolyte contains an acid or acids, or is formed by an acid or acids respectively.
The metallic electrodes employed in elements of said kind consist of lead, but in
view of some drawbacks resulting from the properties of said metal there have
been made trials to replace the lead-electrodes by electrodes consisting of zinc,
especially on account of the higher potential-difference and the lower specific weight
of said latter metal. Another advantage offered by the use of zinc resides in the
elements being able to be left dry, or without their electrolytes respectively, for
any length of time, but, on the other hand, said elements could not be kept on store
with the zinc-electrodes surrounded by the acid, because on the circuit being not
closed the elements were soon rendered useless by the zinc being dissolved by the
acid.
The object of my present invention is to overcome the drawback last mentioned,
and I attain that object in the first place by manufacturing the electrode in a special
manner, and preparing it in a special way, and, in the second place, by making
use of a special sort of electrolyte, as is all fully described hereinafter.
The zinc intended to form the electrode is precipitated electrolytically, preferably
upon lead, and it is caused to form upon the lead or other base a layer of such
thickness that said base is perfectly surrounded by it. Said layer is coherent in
such a degree already that it is perfectly liquor-proof, but to impart to it all the
properties requisite for its proper action in the element it is made still denser by
being amalgamated with mercury.
The electrolyte within which the lead or other base is covered with the zinc,
is composed of a solution of zinc-vitriol, sulphuric acid, and either potash-alum or
ammonia-alum. The base is connected to the negative pole of the source of elec-
tricity; the positive electrode is formed by peroxide of lead. The negative electrode
after being formed within said bath, is taken out of the latter, amalgamated (as
already mentioned) and again put into the bath, when another layer of zinc is
electrolytically precipitated upon it. This second layer is distinguished by being
extremely hard, and, what is most important, affected by sulphuric acid only in
an extremely slight degree; in fact, the dissolution of the zinc by the acid is so
very small, that practically the loss may be entirely neglected.
An important point in the manufacture of my improved electrode consists in
avoiding local currents, in that otherwise the density of the two layers of zinc and
the coherence of them might be impaired. To avoid said currents I prefer to
arrange the lead (a piece of sheet-lead, forming the base for the electrode in
question) upon a piece of tube -E consisting of an insulating material. Said tube
is provided with an aperture or a hole situated below the layer of lead F. The

page_text: wine G for connecting the lead, or the electrode respectively, to the source of elec-
tricity is passed through said aperture or hole, and is soldered to the inner surface
of said layer F. Thereafter the space of the tube E is filled out with any non-
conducting mass, for instance resin. The whole is then ready to be put into the
electrolyte, and to receive the first layer of zinc. By constructing the electrode
in the manner described I get every portion of the lead tightly covered with the
zinc, anu I prevent the electrode against forming in itself a galvanic element (con-
sisting of zinc, lead, and the electrolyte).
Electric accumulators furnished with electrodes of the kind afore described
yield a current of an extraordinarily high tension. A cylindrical accumulator,
for instance, yields in general a tension of 2, 5 Volts, but when freshly charged the
tension amounts even to 2, 7 Volts. This result is due to the particular chemical
composition of the zinc, as gained by the method above stated, because said zinc
is nearly pure, and contains but a few per cents aluminum and lead. This fact
becomes obvious by an examination of the occurrences within the accumulator,
because it is then found, that on charging the latter there precipitates more zinc
than corresponds to theory. A very long series of observations has shown that the
precipitation of the zinc amounts to 1,250 gramin per Ampère-hour, whereas only
1,21 gramm are demanded by the theory. The great resistability of the
electrode against the action of sulphuric acid is well explained by all that, as is
also the fact that one succeeds in producing the electrode on an electrolytic way
only if a plate of peroxide of lead is used as positive pole.
Dated this 2nd day of November, 1896.
HENRY LEITNER.
By Gen. H. Rayner,
Agent for the Applicant.
COMPLETE SPECIFICATION.
Improvements in and connected with Primary and Secondary
Galvanic Elements.
I, HENRY LEITNER of 207, Piccadilly, London, W., late of 39 Elsasser Strasse,
Berlin, Germany, Chemist, do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement.―
This invention relates mainly to secondary elements of the kind in which the
electrolyte contains an acid or acids, or is formed by an acid or acids respectively.
The metallic electrodes usually employed in elements of said kind consist of lead,
but in view of some drawbacks resulting from the properties of the said metal,
some have tried to replace the lead-electrodes by electrodes consisting of zinc,
especially as it has a higher potential difference and less specific weight than lead.
Besides lead kathodes depend for their efficiency on the amount of exposed surface,
on account of the insolubility of the lead salt formed which is not the case with
zinc. Another advantage offered by the use of zinc is that the elements may be
left dry, or without electrolyte, for any length of time. On the other hand these
elements could not hitherto be kept charged when the zine-electrodes were surrounded
by the acid, because on the circuit being left open the elements were soon rendered
useless by the zinc being dissolved by the acid.
The object of my present invention is to overcome the drawback last mentioned,
and I attain that object in the first place by manufacturing the electrode in a special
manner, and, in the second place, by making use of a special electrolyte,, as is all
fully described hereinafter.

page_text: The zinc intended to form the electrode is deposited electrolytically, preferably,
upon lead, and it is caused to form upon the lead or other base a layer of consider-
able thickness, so that said base is perfectly surrounded by it. The said layer is
deposited by the aid of a lead per-oxide plate and the process is conducted slowly.
The consequence is that this layer is coherent in such a degree that it is nearly,
impenetrable to liquid. But to impart to it all the properties requisite for its
proper action in the element, it is made still denser by being amalgamated with
mercury, which has the effect of stopping the pores of the zinc deposit, which
would otherwise form a channel of connection to the inner lead and thus give riso
to local currents.
The electrolyte within which the zinc is deposited on the lead or other base is
composed of a solution of zinc-vitrol, sulphuric acid, and alum, ammonia alum
being preferentially used. The base is connected to the negative pole of the source
of electricity; the positive electrode must be formed of peroxide of lead. The
negative electrode after being formed within said bath is taken out of the latter,
amalgamated (as already mentioned) and again put into the bath when another
layer of zinc is electrolytically deposited upon it. This second layer like the former
is distinguished by being extremely hard though it is well to make it more porous
than the first layer by conducting the process more rapidly. A very important
point is that such a layer is affected by sulphuric acid only in an extremely slight
degree, in fact the dissolution of the zine by the acid is so very small that practically
the loss may be neglected.
An important point in the manufacture of my improved electrode consists in
avoiding local currents as otherwise the density of the two layers of zinc and the
coherence of them might he impaired. To avoid such currents I prefer to arrange
the lead (a piece of sheet lead forming the base for the electrode in question,) upon
a piece of tube consisting of an insulating material. In order that the construction
of my new electrode and the way of forming it may be clearly understood, I will
describe the same in detail with reference to the drawings accompanying the
Provisional Specification.
Fig 1 shows the core or foundation of my electrode, Fig 2 shows the completely
formed electrode.
I first take a tube E of suitable insulating material and a short distance from
one end I drill a hole A through the same. Through this hole I pass a connecting
wire G for the purpose of connecting the electrode up to the source of electricity
I next take a leaden tube F (or a piece of sheet lead rolled up into tubular form)
of a size to fit closely over the said insulating tube and somewhat shorter, say hy,
two inches, than the said tube. I pass this tube over the tube E and dispose it
so that its two ends stand about equidistant from the ends of the said insulating tube.
I then by soldering or otherwise make good electrical contact between the said
leaden tube F and the connecting wire G. That being done I fill in the hollow of
the insulating tube with resin or other suitable insulating material. The composite
tube so formed as shown in Fig 1 constitutes the foundation or core of my im-
proved electrode.
Next, in order to form the electrode I take the core constructed as described in
the preceding paragraph and introduce it into an electrolytic cell the electrolyte
of which is composed of the solution above mentioned and the anode or positive
electrode of which is formed of peroxide of lead. I then pass an electric current
and thereby deposit zinc upon the core and in doing so I am careful to adjust the
strength of the current so as to secure as dense a deposit of zinc as possible. When
the leaden core has been in this way thickly covered and completely enveloped
as shown at B, Fig. 2 with a coherent deposit of zinc, I withdraw it from the
electrolytic hath and amalgamate the surface with mercury as already mentioned.
I then introduce it afresh into the electrolytic bath composed as aforesaid and
deposit a sufficient coating of zinc C upon the amalgamated surface. What is
a sufficient coating must depend upon the duty which the electrode is intended
to fulfil. If it is to be employed in a secondary battery then I take care that the

page_text: outer coating C shall be of such thickness as to contain more metal than will suffice
completely to saturate the quantity of electrolyte contained in the cell of which
it is to form an element. In this way I provide against the contingency of any
exposure of the inner coating of zinc or of the amalgamated surface to the action
of the electrolyte.
It will be evident that electrodes made in accordance with my invention may be
used in primary batteries when it is important to prevent the wasting of the zinc
on open circuit.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:-
(1) The method of producing an electrode for a primary or secondary galvanic
element herein before described, consisting in (1) electrolitically depositing a layer
of zinc upon a suitable base or core by the aid of a lead per-oxide plate (2) amalga-
mating the said layer and (3) depositing electrolytically an outer layer of zinc
in the manner herein before described upon the said amalgamated layer, the said
outer layer being adapted to serve as the active material of a primary or secondary
battery as herein before set out.
(2) In the production of an electrode of the kind described herein, the use for
the purpose of a lead per-oxide plate, substantially as herein set forth.
(3) An electrode for use in primary or secondary electric batteries, produced
by the method of manufacture herein before described and claimed.
(4) An electrode for use in primary or secondary electric batteries consisting of
a cere of lead protected in manner hereinbefore described from contact with the
electrolyte a coating of dense zinc electrolytically deposited upon the said leaden
core, a surface of zinc mercury amalgam upon the said coating of dense zinc and
an outer operative deposit of pure zinc laid down upon the said amalgam surface
au substantially as hereinbefore described and shown.
Dated this 13th day of May. 1897.
GEO. H. RAYNER
37, Chancery Lane, London, Agent for the Applicant.