Improvements in Electrodes and in the Method Employed for Producing them.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improvements in Electrodes and in the Method Employed for
Producing them.
I, KARL KREBS, of Mariendorf, near Berlin, in the Empire of Germany, Engineer,
do hereby declare the nature of this invention to be as follows;-
-
This invention relates to improvements in electrodes and in the method employed
for producing them and its object is to facilitate the manufacture of electrodes
and to render them more reliable in their action and at the same time less sensitive
to vibrations when at work.
For the purposes of my invention I provide the electrodes with a core adapted
to serve in forming them and to be afterwards partly or wholly destroyed and
removed say by a suitable chemical agent, so leaving passages or channels in the
electrodes for the circulation of the electrolyte, or for the escape of gases. Or
I may convert the said core, by chemical means, into a spongy mass or substance
which then forms the base of the active mass in the electrode where such is
desirable. These cores which may consist of perforated sheet iron or iron plates
used singly or in several thicknesses, are advantageously placed in moulds of
suitable material and such moulds are then filled with molten metal, or alloys of
metals may be used and after cooling, both the core and the mould may be
treated as before stated and destroyed. In some instances however I may employ
mechanical means for the destruction or removal, of the mould and the core or of
only one of them.
The plates where several are used, may be placed either close together so as to
be in contact with each other, or space may be left between them to enable
the material, for the formation of the electrode to penetrate therein.
When using plastic material or substances for filling up the perforations or
holes in, and for coating the cores serving in the production of my electrodes
according to this invention, I may dispense with the mould. Electrodes formed
with plastic material are afterwards dried and fired in the usual manner.
Cores for electrodes may also be prepared from burnt earths, such as clay which
can afterwards be destroyed by means of fluoret of hydrogen.
That this 7th doof Ai 1898
S. S. BROMHEAD,
Agent for Applicant,
171, Queen Victoria Street, London, E.C.

page_text: COMPLETE SPECIFICATION.
Improvements in Electrodes and in the Method Employed for
Producing them.
I, KARL KREBS, of Mariendorf, near Berlin, in the Empire of Germany, Engineer,
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 follow-
ing statement:-
This invention relates to an improved method for the production of electrodes.
Trials had been made with the view of producing electrodes by different means,
other than by purely mechanical means as heretofore, and by following a natural
process, but these trials have never given satisfactory results. Thus electrodes
have been produced from metal alloys, or from metallic mixtures, by casting,
moulding or otherwise forming them and having one of the constituent parts in
a more or less suspended state and forming a core which is afterwards dissolved
by a chemical agent and then removed, but these clectrodes possess but little
resistance when subjected to vibration, besides being of irregular consistency
both bodily and chemically.
Another known method, according to which an easily soluble and removable
body, such as ordinary kitchen salt, is coated with a metal, or metals, preferably
lead, has been found equally unsuitable.
According to the improved method hereinafter described the core and the mould
used in the production of electrodes consist only of certain metals, or burnt or
baked earths and other like suitable materials but of such a nature as to enable
them to withstand the temperature and also the chemical action of the molten
metal for casting around them.
The cores, of whatever material and by whatever means they may have been
made, constitute a solid frame throughout and provide regular and symmetrically
arranged passages for the electrolyte and gases, and if desired also provide open-
ings or recesses for the reception of the active mass, and these passages may be
arranged for internal or external action upon the electrode which is being pro-
duced, and furthermore they may be formed to contain solid parts intended to
remain in the finished electrode. A mould is always used in connection therewith.
The casting operation is conveniently effected by immersing the mould containing
the core into the molten metal for a sufficient period to permit of the complete
ejection of all gas and air bubbles from the mould especially when moulds are used
with cores of intricate form requiring to be filled by pressure. After the mould is
properly filled it is removed from the bath and cooled to give the desired degree
of hardness to the casting.
I may however dispense with the casting operation and fill the mould and
the core with a plastic mass by applying pressure if necessary. The bodies thus
produced are dried in any known manner.
The improved method has the common feature with the well known method
herein before mentioned of enabling cores to be produced parts of which can be
decomposed by chemical means.
After casting and firing, the electrodes formed around the said solid frame or
core are subjected to a chemical treatment by the aid of gases or liquids in order
to cause the core to form a chemical combination, capable of being separated either
by a solvent or by mechanical means. Obviously this treatment may also be
applied to the mould or to parts thereof, and again any easily removable parts of
the core may be saved to be used again.

page_text: The mass for use in the cores and moulds as well as the chemical agent may
each be of such a nature that after the action of the substances upon one another
and after the removal of the new chemical combination, or combinations, nothing
remains of either the core or the mould.
The accompanying drawings show, by way of example only a few specimens
of electrodes made in accordance with this invention without however excluding
other forms which may come within the limits of the claim hereunto annexed.
Figs. 1 and 2 represent top-views to an enlarged scale of two portions of sheet-
iron having holes arranged in straight lines.
Fig. 3 is a vertical section on the line s Figure 1.
A number of strips as shown in Figs. 1 and 2 of a length equal to the side of the
electrode, or equal to any desired portion thereof, see Fig. 16, a d, are superposed
and secured together by means of thin bars or rods inserted into the holes near the
ends of the plates or strips and rivetted or screwed, or they may be retained in a
suitable frame fitting all round the edges of the plates or strips.
Fig. 4 shows a sectional view of a number of these plates or strips secured
together.
Supposing that plates or strips are made of sheet iron and that the mould, also
of iron, is made to tightly close and provided with an inlet and with air passages.
The mould as already mentioned, is immersed in a metal bath, for instance in
molten lead and is left to remain until after the escape of all the gas or air bubbles,
when it is removed from the bath completely filled and then cooled.
It is needless to mention that naturally the moulds are formed to allow of
the attachment of the terminals and that the external grooves or channels that
may be required, are all cast in one with the plate.
The electrode with its core of sheet iron having been removed from its mould
is now immersed in diluted sulphuric acid whereupon soluble sulphate of iron
is formed from the iron core until the same has been completely destroyed. The
electrode is now ready to be finished.
If however instead of as above described, the perforated sheets or plates are
made of an alloy which becomes corroded but not decomposed by the diluted
sulphuric acid, and at the same time the material used for the casting remains
unaffected by the acid, a spongy substance will be found in the recesses of the
casting after the chemical treatment and this substance will then become the
basis for the formation of the active mass.
Another type of plates is shown in Figs. 5 and 6 and the plates (of the required
size for the electrode) are superposed in such a manner that the parts a and a¹,-
band b, and c and cover one another as is indicated at din Fig. 6. (In Fig. 7.
are shown 5 superposed plates.) The plates may likewise be secured together by
rivets or they may only be pressed together in the mould. The above type is
suitable for use in a casting, or it may be filled with a carbon paste and then
baked.
"
The electrodes being so formed, when the iron core is removed are ready for
filling with the active mass, having diagonal openings which may serve as passages
for the escape of gases. The openings are shown in Fig. 7.
Fig. 8 shows another perforated plate in which a ragged edge (not shewn) is
left around the holes for the purpose of creating an air space between adjacent
plates. By placing several of such plates together, 6 for example as shown in
Fig. 9 (being a section on the line s Fig. 8) and then connecting them by means
of pins which fit the holes as indicated by the black sections, in Fig. 8 and by a
and c in Fig. 9 a suitable core is then obtained which is capable of being treated
in the same manner as described with reference to that shown in Figs. 1 to 4.
A slightly modified method is adopted in the production of cores and is shown
in Figs. 10 and 11. A number of separate small fluted, or screw-threaded or
otherwise formed cores having hexagonal heads are securely placed into the
mould as shown in the figures. The recesses left between these cores are filled
in as before described.

page_text: Round headed cores may be used to produce a similar effect and these may
serve in couples for closing such cells. The cores with this type of plates are made
of baked earths containing metals, while the materials for the electrodes consist
of carbon paste containing metals. Baked clay cores can afterwards be destroyed
by means of hydrofluoric acid.
The same principle is carried out with reference to Figs. 12, 13, and 14, the last
two figures of which are taken on the lines Fig. 12. The separate small cores
may be secured in a base plate p Fig. 13 by the aid of separating pieces d and
thus form a uniform core of the required size, or they may be provided at their
ends with projections (see Fig. 14) so as to form air spaces between them and keep
them securely in position in the mould. This construction also allows, similarly
to those previously described, of various combinations in the choice of cores,
electrodes and core destroying agents.
Figs. 15 and 16 show constructional arrangements for evenly or uniformly
shaped electrodes.
By using a mould and cores, of the form a, b, c, d Fig. 16 and constructed in
accordance with any of the herein described methods, or in any other similar
manner, and by leaving between them channels or passages for the reception of
the materials for the electrode either by casting or by filling up with plastic
material, electrodes having cross-bars such as n, o, will be produced consisting of
a single piece which is of a uniform and homogeneous nature throughout.
I may mention also that by the use of bars, or the like which can afterwards be
destroyed by chemical agents, the cores may be provided with channels such
as ek Fig. 16, or f, i and h, g Fig. 15, with a view of facilitating the escape of
gases or for allowing the circulation of the electrolyte in electrodes produced by
any of the herein described methods. The said bars may serve also for holding the
parts of the core in position. By using bars of a material unaffected by the
chemical agents they will naturally remain and form part of the electrode, and
then serve either as stiffeners or as conductors for the current.
Electrodes having a solid central part or partition can be produced by arranging
parallel to one another two equally sized cores of a form either as shown in Figs. 1
to 4, or 5 to 7, or 8 and 9. These cores are secured in the mould with a space to
suit the required thickness of the middle wall or partition. I would here state
that in lieu of the perforated sheets or plates woven wire or pleated metal strips
may be used, and that the arrangement of core construction shown at Figs. 10
and 11 may be carried out with smooth or shaped rods or bars by slightly modi-
fying the arrangement.
My improved method for the production of electrodes as compared with the
herein before mentioned decomposing process has the advantage of providing a
systematically arranged and open-work self supporting carrier filled with the
decomposed substance which latter afterwards forms the principal part of the
active mass and is intimately combined with the said carrier, thus combining
great efficiency as regards conductivity with stability or strength in the electrodes.
Compared with the old and known methods the superiority of my method con-
sists in employing cores, not a salt as heretofore, of metals, alloys, or of plastic
material which is afterwards baked, and of systematical and minutely perfect shape
and form which nevertheless is strong enough to withstand the strain due to the
casting or the baking operations without fear of deterioration. This advantage
fully compensates for the objection that the core cannot be destroyed in a few
minutes but requiring days and even weeks to accomplish.
Having now particularly described and ascertained the nature of my said in-
vention and in what manner the same is to be performed I declare that what I
claim is:
The manufacture of electrodes from castings of metals, or of alloys, or by
moulding and baking plastic materials by the aid of frames or cores and moulds,
such cores and moulds after the casting operation, or after the moulding and

page_text: baking operation, being finally destroyed either entirely or partially by means
of chemical agents which convert them into soluble or other chemical compounds
and so allow of separating them, if desired substantially as hereinbefore described,
Dated this 5th day of December 1898.
S. S. BROMHEAD,
Patent Agent, 171, Queen Victoria Street, London, E.C.