Improvements in and relating to Electric Accumulators or Storage Batteries.
Year: 1897

page_text: Date of Application, 23rd June, 1897
Complete Specification Left, 22nd Mar., 1898-Accepted, 7th May, 1898
PROVISIONAL SPECIFICATION.
Improvements in and relating to Electric Accumulators or Storage
Batteries.
+
We, ARTHUR HEINEMANN, Chemist, of 78, Koniggratzerstrasse, Berlin, and
WILHELM SCHAFER, Engineer, of Zehdenick a/H, both in the German Empire,
do hereby declare the nature of this invention to be as follows: ―
For absorbing the electrolyte in electric accumulators various materials have
heretofore been employed, such as gypsum, silicic acid, gelatine and the like, in
order, in this way, to produce a so-called "dry" battery or accumulator-cell, that
is to say, a battery or accumulator-cell from which, notwithstanding its being
unsealed, no liquid can run out when it is brought into various positions; the
said absorbing or drying materials have many disadvantages of which two are
more especially important. In the first place, they are liable, during use, to
chemical and electro-chemical changes whereby the absorbing or drying material
itself as well as the electrodes of the accumulator, are more or less rapidly
destroyed; at the same time varying, and often very considerable fractions of the
charging current are absorbed by these changes or reactions and thus the efficiency
of the accumulator is reduced. Secondly, these absorbing or drying materials are
not sufficiently capable of returning into contact with the electrodes after they
have been forced away therefrom during charging by the normal evolution of gas,
and it is consequently necessary to pour a thin layer of liquid onto the solidified
electrolyte in order to maintain the requisite intimate contact between the
electrodes and the electrolyte. By this operation, however, the special purpose of
constructing "dry" accumulators is defeated, since the liquid can then be easily
spilled. The requirements for a suitable filling material for absorbing the
electrolyte are accordingly the following, viz.:-The filling material should not
conduct electricity; it must be perfectly indifferent to or unaffected by the elec-
trolyte and the electric current; and finally it must be capable of applying itself
so closely to the electrodes that a layer of liquid is not required on the top thereof.
These requirements are satisfied by using chemically pure wood-charcoal as a
filling material, this, like the diamond, is a non-conductor of electricity, whilst
other kinds of carbon, such as graphite, many other kinds of animal charcoal, and
all carbons which have been subjected to an especially high temperature or glowing
heat and have thereby become graphitic, such as coke, incandescent-lamp-carbon,
and the like, possess a more or less good conductivity approximating to that of the
metals. If the inorganic and organic constituents be removed as completely as
possible from ordinary wood-charcoal, the thus purified wood-charcoal is perfectly
indifferent to or unaffected by the action of the electric current and by dilute
sulphuric acid such as is used as an electrolyte in accumulators. This wood-
charcoal does not react chemically either with lead or with the oxides thereof, and is
not destroyed or decomposed either by the chemical reagents present in the accumu-
lator or by the electric current. Such wood-charcoal possesses, by reason of its

page_text: high porosity due to the original cellular structure of the wood, an extraordinarily
high power of absorption and permeability for gases and liquids.
The wood-charcoal preferably employed for our improved accumulator, can be
obtained by carbonizing wood or other suitable vegetable matter by the dry
method (by destructive distillation) or by the wet method. (by the action of sul-
phuric acid), and is subjected to a process of purification from inorganic and
organic constituents in the following manner, viz.:-In the first place the pieces
of charcoal are powdered and treated with dilute mineral acid, preferably in a
warm state, for a long time. The mineral acid, dissolves out the potash and
other salts contained in the wood-charcoal. In addition, the wood-charcoal so
treated, as a rule, still contains a number of organic substances, to remove which
the charcoal is advantageously again heated to a glowing heat. These operations
can be repeated until all organic and inorganic impurities or constituents have
been sufficiently removed from the wood-charcoal. The wood-charcoal is then
again powdered and is now ready for use as a filling material. The application of
this filling material is effected as follows: the electrode plates are set up in the
cell or containing vessel and the remaining space then filled up with the finely
powdered chemically-pure wood-charcoal. In this process it is advantageous to
press or stamp the charcoal-powder into the intermediate spaces. After that,
operation, so much dilute sulphuric acid, in the condition in which it is to be
used in the accumulator, is poured in, that, on inversion of the vessel, no acid will
run out. In connection with this filling, the peculiar observation will be made,
that notwithstanding the fact that the spaces which the accumulator-plates leave
in the containing vessel are closely filled with wood-charcoal powder, yet almost as
much dilute sulphuric acid can be put into the vessel as if the charcoal-powder were
not present. This fact is explained by the extraordinary porosity of the wood-
charcoal powder. The amount of the electrolyte accordingly suffers no diminution
worth mentioning by the conversion of the accumulator into a "dry" accumulator,.
although the object, viz.:-that the filling, by reason of the mechanical union of.
the liquid, shall behave in a similar manner to a solid body, is as, perfectly
attained as in the "dry" accumulators heretofore known.
Moreover the filling with wood-charcoal determines two distinctive features of
advantage from the technical point of view over the ordinary wet accumulator..
In the first place the wood-charcoal filling prevents the formation of the crystalline
lead sulphate, which is observed in the other known wet or dry accumulators and
which results in the certain destruction of the electrodes. This action can be
easily observed if a charged accumulator be short-circuited and allowed to stand.
for a month. Whilst an ordinary wet accumulator in such a condition would be.
entirely destroyed by the formation of the said crystalline sulphate, in accumu-
lators filled with wood-charcoal powder, this formation of sulphate cannot be
noticed at all. This peculiar fact, which is of extreme value, can be easily.
explained, since the sulphuric acid, by reason of its physical union with the
charcoal, is prevented from circulating freely and consequently the process of
crystallization of the originally non-crystalline sulphate of lead cannot take place.
In the second place the mean value of the electromotive force of an accumulator
filled with wood-charcoal as the absorbing material is about 0'1-03 volt higher than
the mean electromotive force of an ordinary accumulator.
. Moreover the wood-charcoal when used as above mentioned, forms an extremely.
effective protective covering or sheath for the electrodes of accumulators or storage-
batteries, since the wood-charcoal filling of the accumulator surrounding the
electrodes prevents falling of the active material.
For this last-mentioned purpose various materials have already been suggested,.
such as felt, perforated celluloid, hard India-rubber, parchment paper, asbestos,
etc. used separately or together.
All these means, however, possess the disadvantage that they are acted upon
chemically by the active material, and, with the exception of hard India-rubber,.

page_text: are under the further disadvantage of being disintegrated both by the action of
the electric current as well as by the sulphuric acid. The products of these
reactions are very injurious to the accumulator, reduce its capacity and efficiency
and cause its early destruction.
Since, as may be seen from the above mentioned list of its properties, the
chemically pure carbon is also non-conducting, this disadvantage cannot arise.
Since difficulties often occur in freeing wood-charcoal, made in the ordinary
way, from injurious admixtures or constituents of an inorganic or organic nature;
it is of special advantage to make the wood-charcoal powder directly by carbonizing
saw-dust by means of concentrated sulphuric acid (that is to say, by the above
mentioned carbonization by the wet method). This method of manufacture
simplifies the purification of the carbon and simultaneously produces a charcoal-
powder of great fineness and of a high degree of porosity.
The kinds of carbon found in nature, produced by the decay of wood, such as
peat, especially only slightly carbonized peat fibres, are quite suitable for use as
an absorbing material for electrolytes. These fibres, before use, must obviously be
likewise purified.
The chemically-pure highly porous wood-charcoal can be put directly into the
accumulator in the form of powder. This filling serves both as an absorbent for
the electrolyte and as a protective sheath for the electrodes, as above mentioned.
The wood-charcoal powder can also be formed by mechanical pressure into
envelopes or sheaths into which the electrodes will fit exactly, so that the wood-
charcoal forms a solid casing for the electrodes. This can also be effected by
carbonizing plates of the wood to be carbonized and purifying them as above
mentioned and then arranging these plates around the electrodes. Plates or
casings of this kind made from chemically pure wood-charcoal consequently .act
likewise not only as absorbers but very advantageously also as electrode-sheaths.
The essential feature of the invention will not be altered if any kind of salt be
added to the electrolyte to increase the conductivity thereof or for other purposes,
or if, instead of the sulphuric acid, any other electrolyte be employed.
Improvements in and relating to Electric Accumulators or Storage
Batteries.
We, ARTHUR HEINEMANN, Chemist, of 78, Koniggratzerstrasse, Berlin, and
WILHELM SCHAFER, Engineer, of Zehdenick a/H, both in the German Empire,
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:
For absorbing the electrolyte in electric accumulators various materials have
heretofore been employed, such as gypsum, silicic acid, gelatine and the like, in
order, in this way, to produce a so-called "dry" battery or accumulator-cell, that
is to say, a battery or accumulator-cell from which, notwithstanding its being
unsealed, no liquid can run out when it is brought into various positions; the
said absorbing or drying materials have many disadvantages of which two are
more especially important. In the first place,. they are liable; during use, to

page_text: chemical and electro-chemical changes whereby the absorbing or drying material
itself, as well as the electrodes of the accumulator, are more or less rapidly
destroyed; at the same time varying, and often very considerable fractions of the
charging current are absorbed by these changes or reactions and thus the efficiency
of the accumulator is reduced. Secondly, these absorbing or drying materials are
not sufficiently capable of returning into contact with the electrodes after they
have been forced away therefrom during charging by the normal evolution of gas,
and it is consequently necessary to pour a thin layer of liquid onto the solidified
electrolyte in order to maintain the requisite intimate contact between the
electrodes and the electrolyte. By this operation, however, the special purpose of
constructing "dry" accumulators is defeated, since the liquid can then be easily
spilled. The requirements for a suitable filling material for absorbing the
electrolyte are accordingly the following, viz.:-The filling material should not
conduct electricity; it must be perfectly indifferent to or unaffected by the elec-
trolyte and the electric current; and finally it must be capable of applying itself
so closely to the electrodes that a layer of liquid is not required on the top thereof.
These requirements are satisfied by using chemically pure wood-charcoal as a
filling material, this, like the diamond, is a non-conductor of electricity, whilst
other kinds of carbon, such as graphite, many kinds of animal charcoal, and other
kinds of carbon such as coke, incandescent-lamp-carbon and the like which have
been subjected to an especially high glowing heat and have thereby become
graphitic, possess a more or less good conductivity approximating to. that of the
metals. If the inorganic and organic constituents be removed as completely as
possible from ordinary wood-charcoal, the thus purified wood-charcoal is perfectly
indifferent to or unaffected by the action of the electric current and by dilute
sulphuric acid such as is used as an electrolyte in accumulators. This wood-
charcoal does not react chemically either with lead or with the oxides thereof, and is
not destroyed or decomposed either by the chemical reagents present in the accumu-
lator or by the electric current. Such wood-charcoal possesses, by reason of its
high porosity due to the original cellular structure of the wood, an extraordinarily
high power of absorption and permeability for gases and liquids.
The wood-charcoal preferably employed for our improved accumulator can be
obtained by carbonizing wood or other suitable vegetable matter by the dry
method (by destructive distillation) or by the wet method (by the action of sul-
phuric acid), and is subjected to a process of purification from inorganic and
organic constituents in the following manner, viz.:-In the first place the pieces
of charcoal are powdered and treated with dilute mineral acid, preferably in a
warm state, for a long time. The mineral acid dissolves out the potash and
other salts contained in the wood-charcoal. In addition, the wood-charcoal so
treated as a rule still contains a number of organic substances, to remove which
the charcoal is advantageously again heated to a glowing heat. These operations
can be repeated until all organic and inorganic impurities or constituents have
been sufficiently removed from the wood-charcoal. The wood-charcoal is then
again powdered and is now ready for use as a filling material. The application of
this filling material is effected as follows: --the electrode plates are set up in the
cell or containing vessel and the remaining space then filled up with the finely
powdered chemically-pure wood-charcoal. In this process it is advantageous to
press or stamp the charcoal-powder into the intermediate spaces. After that
operation, so much dilute sulphuric acid, in the condition in which it is to be
used in the accumulator, is poured in, that, on inversion of the vessel, no acid will
run out.
In connection with this filling, the peculiar observation will be made,
that notwithstanding the fact that the space which the accumulator-plates leave
in the containing vessel are closely filled with wood-charcoal powder, yet almost as
much dilute sulphuric acid can be put into the vessel as if the charcoal-powder were
not present. This fact is explained by the extraordinary porosity of the wood-
charcoal powder. The amount of the electrolyte accordingly suffers no diminution
worth mentioning by the conversion of the accumulator into a "dry" accumulator,

page_text: although the object, viz. :-that the filling, by reason of the mechanical union of
the liquid, shall behave in a similar manner to a solid body, is as perfectly
attained as in the "dry" accumulators heretofore known.
Moreover the filling with wood-charcoal determines two distinctive features of
advantage from the technical point of view over the ordinary wet accumulator.
In the first place the wood-charcoal filling prevents the formation of the crystalline
lead sulphate, which is observed in the other known wet or dry-accumulators-and
which results in the certain destruction of the electrodes. This action can be
easily observed if a charged accumulator be short-circuited and allowed to stand
for a month. Whilst an ordinary wet accumulator in such a condition would be
entirely destroyed by the formation of the said crystalline sulphate, in accumu-
lators filled with wood-charcoal powder, this formation of sulphate cannot be
noticed at all. This peculiar fact, which is of extreme value, can be easily
explained, since the sulphuric acid, by reason of its physical union with the
charcoal, is prevented from circulating freely and consequently the process of
crystallization of the originally non-crystalline sulphate of lead cannot take place.
In the second place the mean value of the electromotive force of an accumulator
filled with wood-charcoal as the absorbing material, is about 01-03 volt higher
than the mean electromotive force of an ordinary accumulator.
Moreover the wood-charcoal, when used as above mentioned, forms an extremely
effective protective covering or sheath for the electrodes of accumulators or storage
batteries, since the wood-charcoal filling of the accumulator surrounding the
electrodes prevents falling of the active material.
For this last-mentioned purpose various materials have already been suggested,
such as felt, perforated celluloid, hard India-rubber, parchment paper, asbestos,
etc. used separately or together.
All these means, however, possess the disadvantage that they are acted upon
chemically by the active material, and, with the exception of hard India-rubber,
are under the further disadvantage of being disintegrated both by the action of
the electric current as well as by the sulphuric acid. The products of these
reactions are very injurious to the accumulator, reduce its capacity and efficiency
and cause its early destruction.
Since, as may be seen from the above mentioned list of its properties, the
chemically pure carbon is also non-conducting, this disadvantage cannot arise.
Since difficulties often occur in freeing wood-charcoal, made in the ordinary
way, from injurious admixtures or constituents of an inorganic or organic nature,
it is of special advantage to make the wood-charcoal powder directly by carbonizing
saw-dust by means of concentrated sulphuric acid (that is to say, by the above
mentioned carbonization by the wet method). This method of manufacture
simplifies the purification of the carbon and simultaneously produces a charcoal-
powder of great fineness and of a high degree of porosity.
The kinds of carbon found in nature, produced by the decay of wood, such as
peat, especially only slightly carbonized peat fibres, are quite suitable for use as
an absorbing material for electrolytes. These fibres, before use, must obviously be
likewise purified.
The chemically-pure highly porous wood-charcoal can be put directly into the
accumulator in the form of powder. This filling serves both as an absorbent for
the electrolyte and as a protective sheath for the electrodes, as above mentioned.
The wood-charcoal powder can also be formed by mechanical pressure into
envelopes or sheaths into which the electrodes will fit exactly, so that the wood-
This can also be effected by
charcoal forms a solid casing for the electrodes.
carbonizing plates of the wood to be carbonized and purifying them as above
mentioned and then arranging these plates around the electrodes.
casings of this kind made from chemically pure wood-charcoal consequently act
likewise not only as absorbers but very advantageously also as electrode-sheaths.
The essential feature of the invention will not be altered if any kind of salt be
Plates or

page_text: added to the electrolyte to increase the conductivity thereof or for other purposes,
or if, instead of the sulphuric acid, any other electrolyte be employed.
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 we
claim is:
1. An electric accumulator in which the electrolyte, for example, dilute sul-
phuric acid, is absorbed by a filling of chemically-pure wood-charcoal..
2. An electric accumulator wherein the electrolyte is absorbed by a filling of
chemically-pure wood-charcoal, which surrounds the electrodes either in the form
of powder or of envelopes or sheaths composed of compressed wood-charcoal powder,
or in the form of plates, in such a manner as to serve as a protective sheath or
casing therefor and to prevent the gradual falling out. of the active material in the
use of the accumulator.
1 נ.י.ת
001111
10001
D. YOUNG & Co.,
11 and 12, Southampton Buildings, London, W.C.,
Agents for the Applicants.
D: YOUNG & Co.,
11 and 12, Southampton Buildings, London, W.C.,
Agents for the Applicants.