Improvements in the Formation of Electrodes for use in Primary and Secondary Electric Batteries.
Year: 1890

page_text: Date of Application, 8th Jan., 1890
Complete Specification Left, 3rd Apr., 1890-Accepted, 10th May, 1890
PROVISIONAL SPECIFICATION.
Improvements in the Formation of Electrodes for use in Primary
and Secondary Electric Batteries.
I, LUDWIG EPSTEIN, of Rathenowerstrasse 80, Berlin, Germany, Electical Engineer,
do hereby declare the nature of this invention to be as follows :-
My invention refers to primary and secondary electric batteries and essentially to
those electric accumulators in which lead in a suitable finely divided state acts as the
negative electrode and peroxide of lead as the positive electrode, and in which there is
no coating or pressing of pulverized lead or plumbic oxides or salts of lead on or in
suitable frames or supports. but in which the active part is produced direct on the
lead by means of electro-chemical processes.
This object of this invention is to effect a quick formation of electrodes that combine
durability with great efficiency.
This object is attained by dividing the process of manufacturing the electrodes into
two separate parts, the first part being limited to the making of so called raw elec-
trodes, which are then transformed into positive electrodes with the assistance of an
electric current in an electrolyte containing either diluted sulphuric acid or a suitable
salt of sulphuric acid, while the negative electrodes are formed by a reduction of the
positive electrodes.
In order to obtain the so called raw electrodes that furnish the raw material for the
finished electrodes, bodies consisting of lead of any shape suitable for use as elec-
trodes, are put into water to which has been added a small quantity (say about
1 per cent.) of nitric acid or other acid that will act as a solvent upon lead.
Instead of an acid a small quantity of an alkaline base or a salt that has the property
of dissolving lead, may be put into the water, used for boiling the lead bodies therein.
This water is then heated up to the boiling point and the lead bodies immersed therein
are kept from coming in contact with each other by being suspended, or in any other
suitable way so that the liquid has free access to every part of them. The water is
kept constantly at the boiling point, and the boiling is continued until the metallic
glance that the lead bodies originally had has disappeared and the lead has assumed a
dull grey appearance. The lead bodies thus treated are then taken out of the boiling
water and dried in air. By this treatment there is produced on the lead bodies a
greyish yellow deposit or layer which consists of compounds of lead and which is
characterized by the following properties
1. It is fine grained in structure and has the appearance of mildew.
2. It adheres very firmly to the lead bodies.
3. It is practically insoluble in the electrolyte used for the subsequent treatment,
this electrolyte being essentially composed of diluted sulphuric acid or a salt of
sulphuric acid.
4. It has a great capacity for taking up the gases evolved during the formation of
the electrodes, by means of the electric current so that it is possible to form the
electrodes quickly without it being necessary to reverse the direction of the electric
current.
Instead of drying these lead bodies in air they can be dried after being boiled in
the manner described, in such gases (as for example oxygen and other similar gases)
as will promote the formation of the deposit or layer thereon just described and
characterized.
The lead bodies treated in the above described way then constitute the so called raw
electrodes, from which the positive as well as the negative electrodes are subsequently
formed.

page_text: are put into the electrolyte, lead plates being inserted between them; or the raw
electrodes may be put into the electrolyte together with positive electrodes that
have to be transformed into negative electrodes as will be hereinafter described. The
raw electrodes that have to be formed into positive electrodes are then connected
with the positive pole of an electric generator and the lead plates with the negative
pole of the electric generator by which means the formation of the electrodes by the
action of the electrolyte commences as soon as the current is turned on. In this
process of forming positive electrodes the original greyish yellow colour of the
raw electrodes gradually changes into a deep dark-brown almost bluish black hue
and the process may be considered as completed as soon as the electrodes have
assumed that colour and an abundant development of gases (oxygen in this case) takes
place on the positive electrodes thus formed.
The formation as above described may take place in an electrolyte consisting of
diluted sulphuric acid or of a solution of a suitable sulphate without the addition of
any other substance.
A better product is however obtained in the presence of such an acid in the above
named electrolytes as that towards which the peroxide of lead acts as a base, as for
instance acetic, phosphoric or tartaric acids, but from which solution of peroxide
of lead the latter is precipitated by some other agent present in the liquid. Now
the acids above mentioned although they do not dissolve the peroxide of lead, yet
they act as a solvent upon the lower oxide-minium-which is formed during the
electrical process and the solution contains peroxide of lead which is precipitated by the
diluted sulphuric acid, water as well as sulphuric acid, acting as precipitating agents.
The action may be thus described; under the action of the electric current, part
of the lower oxides of lead formed upon the electrodes connected with the positive
pole of the electric generator is dissolved but is almost instantaneously converted
into peroxide.
I have found that an addition of a half to two per cent. of either of the acids
mentioned is the most advantageous proportion to use and that the lead peroxide
formed in such mixture is far superior to that formed in diluted sulphuric acid or a
solution of a suitable sulphate alone, being of a very fine and hard structure and
changing gradually into the metallic lead on which it has been formed.
For the purpose of forming negative electrodes, I use some of the positive elec-
trodes formed by the process herein before described, instead of the untreated lead
plates inserted between the electrodes which are to be formed into positive electrodes
and I connect them with the negative pole of the electric generator. Instead of
placing the positive electrodes that are to be reduced into negative ones, between raw
electrodes that are to be formed into positive electrodes, they may also be placed
between untreated lead. plates, but it will be easily understood that the latter arrange-
ment is less economical than the former. The oxygen of the peroxide of lead on
the positive electrodes, to be reduced is absorbed by the action of the electric current
and the peroxide of lead is reduced to a certain depth to porous metallic lead.
The process of forming negative electrodes may be considered as finished when
the deep dark brown or bluish black colour of the positive electrodes used for the
purpose has changed into a bluish grey hue and an abundant development of gases
(in this case hydrogen gas) takes place on the negative electrodes thus formed.
The chief advantage in favour of the method, just described is, that for forming.
electrodes of one sort from the raw electrodes prepared in the manner described, a few
hours only are required, and the reversing of the electric current necessary in other..
processes for this operation, is unnecessary, so that in a very short time a great number
of positive as well as negative electrodes can be produced.
Further advantages are also to be found in the fact that electrodes, prepared in
the manner described are very durable in use, and that even when subjected to
numerous charges and discharges there is no crumbling off, scaling, or other deforma-
tion of any part of them. They have also a great storing capacity and owing to their
very great porosity they allow, with comparatively very little weight, very powerful.
charging and discharging currents to pass through them. In consequence of these
こ

page_text: qualities a great saving in the weight or volume of the electrodes or in the time taken
in their charging or discharging according as one or the other of these requirements
may be desirable or necessary can be effected as compared with electrodes prepared
in the usual manner.
Electrodes prepared according to this invention can also be used with advantage in
primary batteries in which peroxide of lead or finely divided lead form one or the
other of the electrodes.
COMPLETE SPECIFICATION.
Improvements in the Formation of Electrodes for use in Primary
and Secondary Electric Batteries.
I, LUDWIG EPSTEIN, of Rathenowerstrasse 80, Berlin, Germany, Electrical
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
following statement :-
My invention refers to primary and secondary electric batteries and essentially
to those electric accumulators in which lead in a suitable finely divided state acts as
the negative electrode and peroxide of lead as the positive electrode, and in which
there is no coating or pressing of pulverized lead or plumbic oxides or salts of lead
on or in suitable frames or supports but in which the active part is produced direct on
the lead by means of electro-chemical processes.
The object of this invention is to effect a quick formation of electrodes that shall
combine durability with great efficiency.
•
This object is attained by dividing the process of manufacturing the electrodes into
two separate parts, the first part being limited to the making of so called raw electrodes,
which are then converted into positive electrodes with the assistance of an electric
current in an electrolyte containing either diluted sulphuric acid or a suitable salt of
sulphuric acid, while the negative electrodes are formed by a reduction of the positive
electrodes.
In order to obtain the so-called raw electrodes that furnish the raw material for
the finished electrodes, bodies consisting of lead of any shape suitable for use as
electrodes, are put into water to which has been added a small quantity (say about
1 per cent.) of nitric acid or other acid that will act as a solvent upon lead. I
generally use nitric acid. Instead of an acid a small quantity (for example about from
to 1 per cent.) of an alkaline base may be employed; or a salt that has the property
of dissolving lead may be used; the alkaline base or the salt, as the case may be,
being put into the water in which the lead bodies are to be boiled. Suitable salts are
for examples permanganate of potash, carbonate of soda, and sulphate of soda; and
suitable percentages would be about as follows, for example about 1% of permanganate
of potash or about 20% of either carbonate of soda or sulphate of soda.
The water in each case is then heated up to the boiling point and the lead bodies
immersed therein are kept from coming in contact with each other by being suspended
or in any other suitable way, but so that the liquid has free access to every part of
them. The water is kept constantly at the boiling point, and the boiling is continued
until the metallic lustre that the lead bodies originally had has disappeared and the
lead has assumed a dull grey appearance. In some cases instead of using either an
acid or an alkaline base or a salt of the kind mentioned I may use both an acid and a
salt these being such as will together produce a substance that will act upon the lead
bodies in the manner and for the purpose set forth. Such are for example nitric acid
and sulphate of manganese. By adding to the water about 1% of nitric acid and
about 1% of sulphate of manganese, there is produced during the boiling process
peroxide of manganese in its nascent state which has an energetic action on the lead
bodies. The lead bodies thus treated are then taken out of the boiling water and dried
by exposure to the air. By this treatment there is produced on the lead bodies' a

page_text: the following properties:
1. It is fine grained in structure and has the appearance of mildew.
2. It adheres very firmly to the lead bodies.
3. It is practically insoluble in the electrolyte used for the subsequent treatment,
this electrolyte being essentially composed of diluted sulphuric acid or a salt of
sulphuric acid.
4. It has a great capacity for taking up the gases evolved during the formation of
the electrodes by the action of the electric current, so that it is possible to form the
électrodes quickly without it being necessary to reverse the direction of the electric
current.
Instead of drying the lead bodies by exposure to air they can be dried (after being
boiled in the manner described) by exposure to the action of other oxidizing gas or
gases that will promote the formation of the deposit or layer thereon just described.
Suitable gases for the purpose are for example oxygen and chlorine, but it is of course.
cheaper to use air.
The lead bodies treated in the above described way then constitute the so called
raw electrodes from which the positive as well as the negative electrodes are sub-
sequently formed.
In order to form. positive electrodes, a number of raw electrodes forming a group,
are put into the electrolyte, lead plates being inserted between them, or the raw
electrodes may be put into the electrolyte together with positive electrodes that have
to be transformed into negative electrodes as will be hereinafter described. The raw
electrodes that have to be formed into positive electrodes are then connected with the
positive pole of an electric generator and the lead plates with the negative pole of the
electric generator by which means the formation of the electrodes by the action of
the electrolyte will commence as soon as the current is turned on. In this process of
forming positive electrodes the original greyish yellow colour of the raw electrodes
gradually changes into a deep dark-brown almost bluish black hue, and the process
may be considered as completed as soon as the electrodes have assumed that colour
and an abundant escape of gases (oxygen in this case) takes place on the positive
electrodes thus formed. For the purpose of forming negative electrodes, I use some
of the positive electrodes formed by the process herein before described, instead of the
untreated lead plates, inserted between raw electrodes that are to be formed into
positive electrodes, and I connect the positive electrodes with the negative pole of the
electric generator. Instead of placing the positive electrodes that are to be reduced
into negative ones, between raw electrodes that are to be formed into positive
electrodes, that may also be placed between untreated lead plates, but it will be easily
understood that the latter arrangement is less economical than the former. The oxygen
of the peroxide of lead on the positive electrodes to be reduced will, during the
process, be absorbed by the action of the electric current and the peroxide of lead will
be completely reduced to porous metallic lead. The process of forming the negative
electrodes may be considered as finished when the deep dark brown or bluish-black
colour of the positive electrodes used for the purpose has changed into a bluish grey
hue and an abundant escape of gases (in this case hydrogen gas) takes place on the
negative electrodes thus formed.
If instead of connecting the raw electrodes with the positive pole of an electric
generator and forming them into positive electrodes as described, the raw electrodes
were connected to the negative pole of the electric generator, the raw electrodes would
be directly converted into negative electrodes. I have however found in practice that
it is much more advantageous to produce the negative electrodes by the reduction of
positive electrodes in the manner described, because such negative electrodes have a
greater capacity than those prepared direct from the raw electrodes.
The formation of the positive and negative electrodes as above described may take
place in an electrolyte consisting of diluted sulphuric acid or of a solution of a
suitable sulphate (such as for example a sulphate of ammonia or of soda or of alumina
or of potash or of magnesia) without the addition of any other suitable substance.

page_text: A better product is however obtained in the presence of such an acid in the above
named electrolytes as that towards which the peroxide of lead acts as a base, as for
instance acetic, phosphoric or tartaric acid, but from which solution of peroxide of
lead the latter is precipitated by some other agent present in the liquid. Now the
acids above mentioned although they do not dissolve the peroxide of lead, yet they
act as a solvent upon the lower oxide minium-which is formed during the electrical
process and the solution contains peroxide of lead which is precipitated by the diluted
sulphuric acid, water, as well as sulphuric acid, acting as a precipitating agent.
The action may be thus described :-
Under the action of the electric current part of the lower oxide of lead formed
upon the electrodes connected with the positive pole of the electric generator is
dissolved but it is almost instantaneously converted into peroxide.
I have found that an addition to the electrolyte of a half per cent. to two per cent.
of either of the acids mentioned, is the most advantageous proportion to use, and
that the lead peroxide formed in such mixture is far superior to that formed in
diluted sulphuric acid or a solution of a suitable sulphate alone, being of a very fine
and hard structure and changing gradually into the metallic lead on which it has been
formed.
The process of formation is then as follows viz. :-In order to form positive or
negative electrodes a number of raw electrodes forming a group are put into the
electrolyte containing diluted sulphuric acid, or a solution of a suitable salt of
sulphuric acid, and either of the acids mentioned and formed into positive electrodes
in the manner hereinbefore described.
To form negative electrodes, from these positive electrodes I place some of the
latter into an electrolyte composed of diluted sulphuric acid or a solution of a suitable
salt of sulphuric acid and connect them to the negative pole of the electric generator
in the manner before described. Care must be taken that the reduction is com-
plete and that no peroxide or other oxides of lead are left on the bodies. In
practice I find it more advantageous to prepare the positive electrodes intended for
use in batteries, by re-oxidizing the negative electrodes made by reducing the
positive electrodes as just described, as by this means the peroxide has a much finer
structure. For this purpose I place some of the reduced or negative electrodes in an
electrolyte of the same composition as that used for their negative formation and
connect them to the positive pole of the electric generator in the manner before
described.
The chief advantage in favour of the methods herein described is, that for forming
electrodes of one sort from the raw electrodes prepared in the manner set forth, a
few hours only are required, and the frequent reversing of the electric current
necessary in other processes for this operation, is unnecessary so that in a very
short time a great number of positive as well as negative electrodes
produced.
can be
Further advantages are also to be found in the facts that electrodes, prepared in
any of the ways described, are very durable in use, and that even when subjected to
numerous charges and discharges there is no crumbling off, scaling, or other
deformation of any part of them. They have also a great storing capacity, and
owing to their very great porosity they allow, with comparatively very little weight,
very powerful charging and discharging currents to pass through them. In conse
quence of these qualities a great saving in the weight or volume of the electrodes or
in the time taken in their charging or discharging according as one or the other
of these requirements may be desirable or necessary, can be effected as compared
with electrodes prepared in the usual manner.
The accompanying drawings illustrate by way of example various forms in which
the electrodes can be made.
Figs. 1 and 1 represent in elevation and horizontal section respectively a simple
form of such an electrode prepared from a plate P which may be produced by casting,
pressing or by cutting out from sheet lead or by any other suitable means and

page_text: ".
which is provided with a lug a for connection with other electrodes to form a group.
Figs. 2 and 2ª represent in elevation and horizontal section an electrode prepared
from a plate which is corrugated to increase the active surface; the corrugations, b
may be vertical as shewn, or horizontal, or inclined. Figs. 3 and 3ª represent in
elevation and horizontal section another form of electrode in which the plate from
which it is made is formed with a number of holes or perforations c that may be of
any desired shape or form. Figs. 4 and 4 represent in elevation and horizontal
section another form of electrode, which for the purpose of providing a large active
surface is made with ribs & which may be arranged vertically as shewn, or horizontally,
or.inclined...
;
Figs. 4 and 4 represent a similar form but duplicated and with deeper ribs.
These ribs may be for example one millimetre apart each rib having say a thick-
ness of three millimetres and projecting say from five to ten millimetres from the
central part of the electrode which may be about three millimetres thick. By
making the spaces between the ribs narrow as in this example they become by my
process completely filled with peroxide of lead or with spongy lead and thus the
completed electrode presents the appearance of a solid with six flat faces as
distinguished and from that of a ribbed plate. I have found that with electrodes
thus formed active material is firmly held between the ribs and excellent contact is
established between the active and conducting parts of the electrodes.
Figs. 5 and 5ª represent in elevation and horizontal section another form of
electrode, wherein a large active surface is obtained by making the plate with a series
of indentations or serrations e.
For many purposes it is advantageous to use an electrode of one polarity having
either of the shapes herein before described, with an electrode of opposite polarity
made to surround the former and in the shape of a box or casing, the inner surface
only of which has been subjected to the electro-chemical processes herein before
described, while the outer surface remains unaltered and may even be protected by
some suitable acid-proof enamel or paint. A cell of this kind is illustrated in vertical
section in Fig. 6 and in horizontal section in Fig. 6. The electrode p of one
polarity and of one of the abovedescribed forms is placed in a box-like compart-
ment n, which constitutes on its inner surface the electrode of opposite polarity.
This box-like compartment is made of lead by casting, pressing or in any other
suitable manner and may be made in one piece or in separate pieces that are after-
wards united together. Suitable separating pieces of non-conducting material on
-the bottom g of the box-like electrode n of the one polarity serve to insulate and
support the electrode p of opposite polarity, while fork-like separators h, which may
be made of ebonite or paraffined wood or other suitable non-conducting material, and
fixed around the electrode p serve to keep the positive and negative electrodes apart.
The cell is provided with a lid k with openings for the lugs a¹ and a² of the two
electrodes, whereby any desired connections either for quantity (parallel) or for
tension (series), can be effected.
The shape of the electrode serving as the receptacle can if desired, be varied in a
like manner to that in which the inner electrode can be varied as herein before
explained with reference to Figs. 1 to 5* inclusive with a like object. Figs. 7, 8
and 9 illustrate in sectional plan some modifications of the surface of these box-shaped
electrodes.
These electrodes both positive and negative are formed in the manner hereinbefore
described with the distinction however, that the electrodes intended to serve as
• receptacles are not electrically formed by placing the metal boxes of which they
consist in the boiling bath and afterwards in the electrolyte in the manner herein-
before described for plate electrodes. They are formed on their inner surface into
raw electrodes by pouring into them the acidulated water or the water to which has
been added a suitable alkali or salt or both an acid and a salt and raising the tem-
perature thereof to the boiling point by putting them into a hot sand or water bath
or by subjecting them to the action of steam or heated air.. For the electrical

page_text: formation also the electrolyte is put into the boxes. Care must be taken that the
outer surface of the boxes shall be protected against the action of the bath and
electrolyte during the forming processes.
The advantages resulting from the use of such electrodes are many; the more
important are the following, viz.:
1. Each cell consists of only one positive and one negative electrode, whereby (a) as
compared with cells composed of a large number of electrodes the labour and
difficulty of making connections by soldering, casting, or other means are obviated;
(b) the danger of short circuits is materially decreased.
2 The cells occupy much less space than those of equal capacity prepared in the
ordinary manner.
.as is
3. There is no or very little risk of damage to the containing vessel such
liable to take place with those made of vitreous or argillaceous material; such as glass,
earthenware and the like.
4. Only one type or only a few types of cells need be manufactured, as any
desired current or potential difference can be obtained by coupling the cells either for
quantity (parallel) or for tension (series).
Electrodes prepared according to this invention can also be used with advantage
in primary batteries in which peroxide of lead or finely divided lead form one or the
other of the electrodes.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. The formation of electrodes for use in primary and secondary electric batteries
by first boiling the lead bodies in weak acidulated water or water otherwise
rendered slightly active as a solvent upon lead as set forth, then exposing the
bodies to the action of air or oxidizing gas and finally subjecting the bodies thus
dried to the action of an electric current in a suitable electrolyte substantially as set
forth.
2. The formation of electrodes for use in primary and secondary electric batteries
by first boiling the lead bodies in weak acidulated water or water otherwise rendered
slightly active as a solvent upon lead as set forth, then exposing the bodies to the
action of air or oxidising gas, then subjecting the bodies thus dried (and whilst
connected to the positive pole of an electric generator) to the action of an electric
current in a suitable electrolyte and finally subjecting the positive electrodes thus
produced (whilst connected to the negative pole of an electric generator) to the
action of an electric current in a suitable electrolyte snbstantially as set forth.
3. The formation of electrodes for use in primary and secondary electric batteries
by first boiling the lead bodies in weak acidulated water or water otherwise rendered
slightly active as a solvent upon lead as set forth, then exposing the bodies to the
action of air or oxidizing gas and then subjecting the bodies thus dried to the action
of an electric current in an electrolyte containing either dilute sulphuric acid, or the
solution of a suitable salt of sulphuric acid, and an acid towards which the peroxide
of lead acts as a base substantially as set forth.
4. The formation of electrodes for use in primary and secondary electric batteries
by first boiling the lead bodies in weak acidulated water or water otherwise rendered
slightly active as a solvent upon lead as set forth, then exposing the bodies to the
action of air or oxidizing gas, then subjecting the bodies thus dried (and whilst con-
nected to the positive pole of an electric generator) to the action of an electric
current in an electrolyte containing either diluted sulphuric acid or the solution of a
suitable salt of sulphuric acid, and an acid towards which the peroxide of lead acts
as a base, and finally subjecting the oxidised lead bodies thus produced (whilst con-
nected to the negative pole of an electric generator) to the action of an electric
current in an electrolyte of diluted sulphuric acid or a solution of a suitable salt of
sulphuric acid substantially as set forth.
5. The formation of electrodes for use in primary and secondary electric batteries

page_text: by first boiling the lead bodies in weak acidulated water or water otherwise rendered
slightly active as a solvent upon lead as set forth, then exposing the bodies to the
action of air or oxidizing gas, then subjecting the bodies thus dried (and whilst
connected to the positive pole of an electric generator) to the action of an electric
current in an electrolyte containing either diluted sulphuric acid, or the solution of a
suitable salt of sulphuric acid, and an acid towards which the peroxide of lead acts
as a base, then subjecting the oxidised lead bodies thus produced (whilst connected
to the negative pole of an electric generator) to the action of an electric current in
an electrolyte of diluted sulphuric acid or a solution of a suitable salt of sulphuric
acid and finally subjecting the reduced bodies thus produced (whilst connected to the
positive pole of an electric generator) to the action of the electric current in an
electrolyte such as last mentioned substantially as set forth.
6. The formation of electrodes such as are respectively shewn in figures 1 and 1;
Figs. 2 and 2; Figs. 3 and 3ª ; Figs. 4 and 4; Figs. 4b and 4°; Figs. 5 and 5;
Figs. 6 and 6; Fig. 7; Fig. 8; and Fig. 9 of the drawings annexed, by the
processes respectively described.
7. The use in conjunction with an electrode made according to this invention of
a second electrode made in the form of a receptacle for the first mentioned electrode
and having its inner surface only rendered active by one of the previously described
methods.
Dat
SA1 1900
LUDWIG EPSTEIN.
W. Lloyd Wise,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.