improvements in Electrodes, chiefly designed for Use in Electric Accumulators.
Year: 1894

page_text: Date of Application, 15th Sept., 1894
Complete Specification Left, 12th June, 1895-Accepted, 13th July, 1895
PROVISIONAL SPECIFICATION.
improvements in Electrodes, chiefly designed for Use in Electric
Accumulators.
We, WILHELM SCHÄFER, Electrical Engineer, and ARTHUR HEINEMANN,
Chemist, both of No. 137 Alte Jacobstrasse, Berlin, in the Empire of Germany,
do hereby declare the nature of this invention to be as follows :—
The subject of this invention is an improved process of manufacturing electrodes
adapted for use in electrical apparatus, and more particularly in accumulators of
electrical energy,
the improved electrodes having the advantage over those employed
hitherto, that they combine a great working capacity with very considerable strength
or durability.
In the case of electrodes of electrical accumulators or storage batteries, it is
particularly important that, in addition to possessing the greatest possible capacity
for storing up oxygen, they should be sufficiently strong, or display a sufficient
power of resistance, to withstand both external mechanical action and internal
molecular influences.
The method which has been usually adopted hitherto in the construction of
electrodes of this class, was to apply to the electrode-supports certain insoluble
lead compounds, or in some cases simply powdered lead, or lead filings, and to secure
them to such supports by means of suitable mechanical binding or adhesive
materials. These materials to be capable of retaining the lead compound or lead
filings on the support, had to be insoluble in sulphuric acid, and it was also
necessary that they should offer a sufficient resistance to electrolytic decomposition.
The consequence was that the binding materials which had to be chosen, were
necessarily non-conductors of electricity; owing to which circumstance the
conductivity and effective usefulness of the electrodes were materially reduced,
since the lead, or compound of lead, being the only conductor, must have been
In addition
rendered less active by the insulating nature of the binding material.
to this, the molecular force, due to the chemical changes taking place whilst the
electrodes were being charged and discharged, through contraction and expansion,
caused the particles of lead to be detached from the particles of the mechanical
binding material which those chemical actions did not affect. And the necessary
consequence of this was that the positive electrodes were doomed to destruction
within a comparatively brief period of time.
Now the object of the present invention is to obviate all these drawbacks by
causing each particle of lead to display its full activity, both chemically and
electrically, while ensuring at the same time a close and complete adhesion of the
different particles to each other. This object is attained by the employment, in
the manufacture of the plates, which are to be converted into electrodes, of a
compound known as glycerate of lead.
It is obvious that the said electrodes may also be employed in primary batteries
or in electrolytic cells for chemical decomposition or in other apparatus in which
accumulator electrodes can be employed.
Glycerine has the property, when brought into contact with oxide of lead, of
forming therewith a combination or compound which will, in a few minutes, more
or less according to the proportions in which it is mixed, congeal or solidify, so as
to acquire the hardness of stone. The formation of this hard mass, may be

page_text: accounted for by the conglomeration of the glycerate of lead crystals which:
are produced; the composition of the glycerate of lead being represented by the
following formula:-
According to our process the glycerate of lead is converted by the electric
current in the presence of an alkali-permanganate-solution acidulated with sulphuric
acid into a chemical compound of peroxide of lead and of peroxide of
manganese (a lead salt of the manganous acid) thereby oxydizing or decomposing
the glycerine according to the following equation:-
2C»H,O,Pb + 2KMnO, + H,SO, = K,SO, + 2(PbO,MnO,) + C,H,O +
-
С¿H¸О + 3 H₂O.
This equation explains the formation of the compound PbO₂MnO, asked for and
of the by-products, C,H,O, C,HO₂, K₂SO, and H.O. The latter two substances
(K₂SO, and H2O) are electrolytically converted into hydroxide of potassium and
sulphuric acid; but in the presence of an excess of sulphuric acid these products
are reconverted into sulphate of potassium and water. Such conversion and
reconversion may be shown by the following equations:-
====
CH.CH.CO₂H + H2SO4 + KMnO, CH₂O, + C,HO, + к,SO + MnO2.
acrylic acid.
Formic and acetic acid besides sulphate of potassium and dioxide of manganese
are formed and may be further oxydized in a similar manner into carbonic acid
and water. The glycerate of lead does not conduct the electricity and forms a
dense compact, solid and non-porous mass, which is very resistant against the most

page_text: active chemical agents. A simultaneous action of the sulphuric acid, of the electric
current and of the permanganate of an alkali metal is necessary for the chemical
conversion so as to decompose the glycerine and to render the product electrically
conductive. Now the manganese atom goes to the lead atom and a salt PbO,.MnO,
is formed. This salt possesses a special property of giving off its manganese in the
form of permanganic acid by means of oxygen if the lead glycerate serving as
electrode in an accumulator receives electricity, thereby the said oxygen is given
off, which converts the manganese of the said salt. (PbO,MnO,) into the permanganic
acid entering the aqueous sulphuric acid of such accumulator.
This conversion during the said charging process will be explained by the
following equation:
PbОMnO2 + H₂O + 30 = 2 PbO₂ + 2 HM¤О.
During the discharging of such charged accumulator the salt PbO,.MnO, forms
again.
In this manner it is only necessary to form or mould blocks or plates, of the
shape which it is desired to impart to the electrode, from the glycerate of
lead, with or without the employment of a conductor, such as a grid or frame
of lead, or other metal or alloy capable of resisting the action of the sulphuric
acid.
In order to convert these blocks or plates into electrodes, they are subjected
to the action of sulphuric acid containing some of an alkaline permanganate
(such as permanganate of potash or permanganate of soda) and to the action of the
electrical current.
In this manner the glycerine is oxidised, and the peroxide of manganese
separated out so that a strong uniform plate of peroxide of lead and peroxide of
manganese is obtained.
In forming these plates, sulphuric acid having a specific gravity of about
16° Baumé is employed, the strength of the current being gradually increased, and
the liquid kept cool. The quantity of permanganate of potash to be employed
depends on the size of the bath, and the size of the bath is proportioned in
accordance with the dimensions of the plates in course of manufacture, care should
be taken not to introduce too large quantities at once, the addition being effected
in several successive stages as soon as decoloration sets in. Owing to the chemical
(not mechanical) conglomeration or union of the particles which takes place,
electrodes constructed in this manner acquire a far greater strength or firmness
than any electrodes hitberto employed in electric accumulators or similar apparatus ;
and neither concussions nor long continued use will cause any disintegration or
loosening of the "active" material to take place. Our improved electrode is not
liable to become bent or warped, whilst being charged or discharged, since nothing
interferes with expansion owing to the absence of any mechanical binding materials
such as have been used in electrodes hitherto constructed. Furthermore, as idle
or inactive components are entirely dispensed with in these electrode-plates, they
cause no diminution of the capacity of the electric accumulators which they assist
in forming, whence they surpass all the electrodes heretofore employed in efficiency
and durability. Thus, 1 kilogramme of positive electrode material compounded
according to this invention, has a storage capacity of 150 ampère-hours; whereas,
even in the most favorable cases, the old electrodes have attained only one-fifth of
that figure.
It has been stated above, that the glycerate of lead, to be employed in the
manufacture of our improved electrodes is obtainable by the commixture of
glycerine and oxide of lead.
Now practical experiment has repeatedly shown that, for positive electrodes, the
glycerate of lead to be employed should preferably be prepared not with chemically
pure, but with crude glycerine.
Positive electrodes of this description, in connection with which the employment

page_text: of hardened or alloyed lead is recommended for the construction of the conducting
support, have been found extremely durable and effective.
The difference between the effect obtained by the use of crude glycerine, and
that produced by pure glycerine, seemed to be ascribable to the impurities contained
in the former, which impurities, after undergoing the action of the electrolyte
containing the sulphuric acid and the permanganate of the alkali employed, and
also the action of the electric current, form compounds, which influence, in the
inanner above stated, both the molecules of the lead and the molecules of manganese
compounds produced from the electrolyte.
The following substances are contained in the crude glycerine in the condition of
impurities: lime, non-volatile organic matter (such as fatty acids, albumen, rosin,
colouring matter), free acids (such as oxalic acid, butyric acid), insoluble fatty
acids (such as oleic acid), aldehyde, arsenious acid, cane-sugar, white syrup and
grape-sugar.
Of these impurities, the inorganic ones become partly incorporated in the
electrolyte (lime), while the remaining part is converted into gas (arseniuretted
hydrogen).
It has been found by experiment that, while the impurities of the crude glycerine
to a great extent affect the electrodes, formed with such glycerine, in an injurious
manner, they also, on the other hand, exercise a beneficial action on the same, and
that the benefit conferred so much outweighs the harm done, that positive
electrodes, made with glycerate of lead which is obtained from crude glycerine, are
yet, on the whole, more effective than any electrodes produced by other methods.
For negative electrodes, however, the employment of crude glycerine is not advisable,
But on the other hand,
chiefly, it is presumed, on account of the lime it contains.
in the case of negative electrodes, an addition of butyric acid to the chemically
pure glycerine is desirable, as this assists the process of reduction of the glycerate
of lead. Among the impurities of the crude glycerine which render the employment
of the latter, in the preparation of the glycerate of lead compound for positive
electrodes, particularly advantageous, the following may with certainty be named :-
butyric acid, hydracrylic acid, lactic acid, and other similar acids of the same
series, viz., CH2O2 and CH2O2; which acids are transformed in the electrolytic
process, into carbonic acid, formic acid, saturated and unsaturated hydrocarbons,
croton aldehyde, and the like. Owing to this action during the electrolysis,
the molecules of peroxide of lead and of peroxide of manganese are influenced
in such a manner that their storage capacity and efficiency are materially
increased.
In consequence of these facts, which have been discovered and ascertained by
tests, it is advisable, in constructing positive electrodes by the process described
above, to employ crude glycerine in the preparation of the glycerate of lead.
But what will prove of particular advantage, in carrying out this invention, is
the possibility of replacing the crude glyceriue by glycerine to which butyric acid,
hydracrylic acid, lactic acid or other acids of these series have been added.
Positive electrodes produced by this method have, in regard to useful effect and
strength, the further superiority over those which are made of glycerate of lead
obtained from crude glycerine, that they are free from any of the injurious
impurities which the crude glycerine contains.
The electrode-plates are employed and operate in the usual manner.
Dated this 14th low of Sentember 1894
D. YOUNG & Co.,
11 & 12 Southampton Buildings, London, W.C.,
Agents for the Applicants.

page_text: Improvements in Electrodes, chiefly designed for Use in Electric
Accumulators.
We, WILHELM SCHÄFER, Electrical Engineer, and ARTHUR HEINEMANN,
Chemist, both of No. 137 Alte Jacobstrasse, Berlin, in the Empire of Germany,
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 to the manufacture of electrodes adapted for use in
electrical apparatus and more particularly in accumulators of electrical energy,
the improved electrodes having the advantage over those employed hitherto, that
they combine a great working capacity with very considerable strength cr
durability.
In the case of electrodes for electrical accumulators or storage batteries, it is
particularly important that, in addition to possessing the greatest possible capacity
for storing up oxygen, they should be sufficiently strong, or possess a sufficient
power of resistance, to withstand both external mechanical action and internal
inolecular influences.
The method which has been usually adopted hitherto in the construction of
electrodes of this class, was to apply to the electrode-supports certain insoluble
lead compounds, or in some cases simply powdered lead or lead filings, and to
secure them to such supports by means of suitable mechanical binding or adhesive
materials. These materials, in order to be capable of retaining the lead compound
or lead filings on the support, had to be insoluble in sulphuric acid, and it was also
necessary that they should offer a sufficient resistance to electrolytic decomposition.
The consequence was that the binding materials which had to be chosen, were
necessarily non-conductors of electricity; owing to which circumstance the con-
ductivity and effective usefulness of the electrodes were materially reduced, since
the lead, or compound of lead, being the only conductor, must have been rendered
less active by the insulating nature of the binding material. In addition to this,
the molecular force due to the chemical changes taking place whilst the
electrodes were being charged and discharged, through contraction and expansion,
caused the particles of lead to be detached from the particles of the mechanical
binding material which those chemical actions did not affect. And the necessary
consequence of this was that the positive electrodes were doomed to destruction
within a comparatively brief period of time.
Now the object of the present invention is to obviate all these drawbacks by
causing each particle of lead to display its full activity, both chemically and
electrically, whilst ensuring at the same time a close and complete adhesion of the
different particles to each other. This object is attained by the employment, in the
manufacture of the plates, which are to be converted into electrodes, of a compound
known as glycerate of lead.
Glycerine has the property, when brought into contact with oxide of lead, of
forming therewith a combination or compound which will, in a few minutes, more
or less according to the proportions in which it is mixed, congeal or solidify, so as
to acquire the hardness of stone. The formation of this hard mass may be
accounted for by the conglomeration of the glycerate of lead crystals which are

page_text: produced; the composition of the glycerate of lead being represented by the
following formula :-
ISO = K₂SO + 2 (PbO₂MnO) + CHO +
CH,CH.CO₂H + H₂SO, + KMnO₁ = CH₂O₂ + C₂HO₂ + K₂SO₁ + MnO,
acrylic acid.
Formic and acetic acid, besides sulphate of potassium and dioxide of manganese,
are formed and may be further oxydized in a similar manner into carbonic acid
and water. The glycerate of lead does not couduct the electricity and forms a
dense, compact, solid and non-porous mass, which is very resistant against the

page_text: most active chemical agents. A simultaneous action of the sulphuric acid, of the
electric current and of the permanganate of the alkali metal is necessary for
the chemical conversion so as to decompose the glycerine and to render the product
electrically conductive. Now the manganese atom goes to the lead atom ani a
salt PbO,MnO2 is formed. This salt possesses a special property of giving off its
manganese in the form of permanganic acid by means of oxygen if the lead
glycerate serving as electrode in an accumulator receives electricity, thereby the
said oxygen is given off, which converts the manganese of the said salt
(PhO2MnO2) into the permanganic acid entering the aqueous sulphuric acid of
such accumulator.
This conversion during the said charging process will be explained by the
following equation
agam.
In this manner it is only necessary to form or mould blocks or plates, of the
shape which it is desired to impart to the electrode, from the glycerate of
lead, with or without the employment of a conductor, such as a grid or frame
of lead, or other metal or alloy capable of resisting the action of the sulphuric
acid.
In order to convert these blocks or plates into electrodes, they are subjected to
the action of sulphuric acid containing some of an alkaline permanganate (such as
permanganate of potash or permanganate of soda) and to the action of the electric
current.
In this manner the glycerine is oxidised, and the peroxide of manganese
separated out, so that a strong uniform plate of peroxide of lead and peroxide of
manganese is obtained.
In forming these plates, sulphuric acid having a specific gravity of about
16° Baumé is employed, the strength of the current being gradually increased, and
the liquid kept cool. The quantity of permanganate of potash to be employed
depends on the size of the bath, and the size of the bath is proportioned in
accordance with the dimensions of the plates in course of manufacture. Care
should be taken not to introduce too large quantities at once, the addition being
effected in several successive stages as soon as decoloration sets in. Owing to the
chemical (not mechanical) conglomeration or union of the particles which takes
place, electrodes constructed in this manner acquire a far greater strength or
firmness than any electrodes hitherto employed in electric accumulators or similar
apparatus; and neither concussions nor long continued use will cause any
disintegration or loosening of the active material. Our improved electrode is not
liable to become bent or warped, whilst being charged or discharged, since nothing
interferes with expansion owing to the absence of any mechanical binding materials
such as have been used in electrodes hitherto constructed. Furthermore, as idle or
inactive components are entirely dispensed with in these electrodes or plates, they
cause no diminution of the capacity of the electric accumulators of which they form
a part; they therefore surpass the electrodes heretofore employed in efficiency and
durability. Thus, 1 kilogramme of positive electrode material compounded
according to this invention has a storage capacity of 150 ampère-hours; whereas,
even in the most favourable cases, the old electrodes have attained only one-fifth
of that figure.
It has been stated above, that the glycerate of lead, to be employed in the
manufacture of our improved electrodes, is obtainable by the commixture of
glycerine and oxide of lead.
Now practical experiment has repeatedly shown that, for positive electrodes, the
glycerate of lead to be employed should preferably be prepared, not with chemically
pure, but with crude glycerine.

page_text: Positive electrodes of this description, in connection with which the employment
of hardened or alloyed lead is recommended for the construction of the conducting
support, have been found extremely durable and effective.
The difference between the effect obtained by the use of crude glycerine, and
that produced by pure glycerine, seemed to be ascribable to the impurities contained
in the former, which impurities, after being subjected to the action of the electrolyte
containing the sulphuric acid and the permanganate of the alkali employed, and
also to the action of the electric current, form compounds, which influence, in the
manner above stated, both the molecules of the lead and the molecules of the
manganese compounds produced from the electrolyte.
The following substances are contained in the crude glycerine in the condition
of impurities, viz.-lime, non-volatile organic matter (such as fatty acids albumen,
rosin, colouring matter), free acids (such as oxalic acid, butyric acid), insoluble
fatty acids (such as oleic acid), aldehyde, arsenious acid, cane-sugar, white sirup
and grape-sugar.
Of these impurities, the inorganic ones become partly incorporated in the
electrolyte (lime), while the remaining part is converted into gas (arseniuretted
hydrogen).
But on the
It has been found by experiment that while the impurities of the crude glycerine
to a great extent affect the electrodes, formed with such glycerine, in an injurious
manner, they also, on the other hand, exercise a beneficial action on the same, and
that the benefit conferred so much outweighs the harm done, that positive
electrodes, made with glycerate of lead which is obtained from crude glycerine, are
yet, on the whole, more effective than any electrodes produced by other methods.
For negative electrodes, however, the employment of crude glycerine is not
advisable, chiefly it is presumed, on account of the lime it contains.
other hand, in the case of negative electrodes, an addition of butyric acid to the
chemically pure glycerine is desirable, as this assists the process of reduction of
the glycerate of lead. Among the impurities of the crude glycerine which render
the employment of the latter, in the preparation of the glycerate of lead compound
for positive electrodes, particularly advantageous, the following may with certainty
be named-butyric acid, hydracrylic acid, lactic acid, and similar acids of the
same series, viz. :-CHO, and CH2O3; which acids are transformed, in the
electrolytic process, into carbonic acid, formic acid, saturated and unsaturated
hydrocarbons, croton aldehyde, and the like. Owing to this action during the
electrolysis, the molecules of peroxide of lead and of peroxide of manganese are
influenced in such a manner that their storage capacity and efficiency are materially
increased.
In consequence of these facts, which have been discovered and ascertained by
tests, it is advisable, in constructing positive electrodes by the process above
described, to employ crude glycerine in the preparation of the glycerate of lead.
But what will prove of particular advantage, in carrying out this invention, is
the possibility of replacing the crude glycerine by glycerine to which butyric acid
hydracrylic acid, lactic acid or other acids of these series have been added
Positive electrodes produced by this method have, in regard to useful effect and
strength, the further superiority over those which are made of glycerate of lead
obtained from crude glycerine, that they are free from any of the injurious
impurities which the crude glycerine contains.
The improved electrodes or plates are employed and operate in the usual manne
in primary and secondary batteries and other apparatus in which such electrode
can be employed, e.g. electrolytic decomposing cells and the like.
Having now particularly described and ascertained the nature of our said inven
tion and in what manner the same is to be performed we declare that what w
claim is :-
First. The herein described process of manufacturing electrodes of glycerate o
lead, with or without the employment of conducting supports, the said glycerate o

page_text: lead being subjected to the oxidizing action of the electric current, in the presence
of the permanganate of an alkali, and of sulphuric acid.
Second. The modification of our process for the manufacture of positive
electrodes, wherein the glycerate of lead employed is produced by means of
glycerine in the presence of butyric acid, hydracrylic acid, lactic acid, or other
acids of these series, or by means of crude glycerine, substantially as described.
Third. The modification of our process for the manufacture of negative.
electrodes, in which chemically pure glycerine with an admixture of butyric acid.
is used in the production of the glycerate of lead, substantially as described.
Fourth. An electrode or plate consisting mainly of glycerate of lead, with or
without a conducting support, which glycerate of lead is, by means of an electrolyte
containing sulphuric acid and permanganate, converted into peroxide of lead
combined with peroxide of manganese.
Fifth. An electrical accumulator or similar apparatus constructed with electrodes.
or plates manufactured in accordance with either of the modifications of our
process, substantially as hereinbefore described.
1
101 1
T 1005
D. YOUNG & Co.,
11 & 12 Southampton Buildings, London, W.C.,
Agents for the Applicants.