Improvements relating to Electric Accumulators or Secondary Batteries, and to the Manufacture of Plates or Electrodes therefor.
Year: 1892

page_text: Date of Application, 13th Aug., 1892
Complete Specification Left, 13th May, 1893-Accepted, 5th Aug., 1893
PROVISIONAL SPECIFICATION..
Improvements relating to Electric Accumulators or Secondary
Batteries, and to the Manufacture of Plates or Electrodes
therefor.
1, ARTHUR JAMES SMITH, of Kingston-on-Thames, in the County of Surrey,
Chemist, do hereby declare the nature of this invention to be as follows:-
My invention relates to electric accumulators or secondary batteries and to the
manufacture of plates or electrodes therefor, and chiefly designed to facilitate and
augment the electro-chemical actions and reactions which take place in the
accumulator, and thus increase the efficiency of the same in proportion to its
dimensions and weight as compared with the accumulators hitherto devised.
My said invention relates more particularly to accumulators or secondary
batteries of the kind or class wherein lead plates or electrodes are employed, and
wherein the storage of energy is effected by the de-oxidation of one of the lead
electrodes and the peroxidation of the other electrode. The electrodes for
accumulators of this kind or class are usually made by first producing lead plates
coated with a suitable oxide of lead, and then subjecting the same to the action of
electric currents in the accumulator. And in most of the endeavours hitherto made
to increase the efficiency and durability of accumulators of this kind or class, the
aim of the inventor has been to produce a lead plate or electrode having as large a
superficial area as is consistent with the proper strength and durability of the said
plate or electrode, in order to have as large a surface of the metallic lead as
practicable in contact with the active material. This result has, in some measure,
been obtained by making the electrodes of perforated plates or gratings, the
holes or cells of such plates or gratings being filled with the active material.
It has also been proposed to make the electrodes by subjecting masses of lead
wire or the like to compression and thus producing what are termed "felted"
plates, and then "forming" the electrodes in the well-known manner, that is to say,
by causing de-oxidation of the one electrode and peroxidation of the other electrode
by repeated charging and discharging of the accumulator, with reversals of the
current if necessary.
It has also been proposed to make plates or electrodes by agglomerating under
pressure, mixtures of lead oxides with lead filings or the like, or with ammonium
sulphate and other substances.
The result sought to be attained in each case has been to bring as much as
possible of the metallic lead into contact with the active material.
I am not aware, however, that any suggestions have heretofore been made for
facilitating and augmenting the electro-chemical actions and reactions by the
intimate intermingling and kneading of the particles of the lead oxide with those of
the lead plates.
Now according to my invention, instead of adopting expensive methods of
casting lead gratings or perforated plates of peculiar shape, and then applying
minium or other lead oxide to the said gratings or plates, I take plates or sheets of
lead of any suitable dimensions, and apply the oxide of lead thereto and cause the
particles of the said oxide to intermingle, by means of a mechanical process, very
intimately with those of the metallic lead on one or both sides of the plate to a
suitable depth, preferably leaving a portion or layer of the metallic lead solid or

page_text: undisturbed in the middle of the plate to afford an efficient support for the active
material and a path of sufficient conductivity for the electric current.
For this purpose, I find it advantageous to proceed as follows, that is to say :-
I first spread upon the lead plate, by any convenient means, a layer of minium or
other suitable oxide of lead, preferably in the form of dry powder, and I then
force the particles of such oxide into the lead plate and intimately mix them with
the particles of the metallic lead. I effect this result by repeatedly driving into
the plate covered with the oxide, a bundle of needles or pointed rods. More lead
oxide is applied to the plate and kneaded into the same from time to time as may be
required. I treat in this manner both the negative and the positive or in other
words the de-oxidized and the peroxidized plates.
I do not confine myself to the use of any particular devices for effecting the
intermingling or kneading of the particles of oxide with those of the lead plate, as
the result will be the same in any case providing the particles of oxide and of
metallic lead are intermingled and kneaded so as to bring a very great number of
the particles of oxide into close contact with particles of the metallic lead and cause
them to cohere thereto.
By manufacturing the plates or electrodes in this manner, I am enabled to
dispense with the process of "forming" the electrode, my improved accumulator
being ready for use as soon as the plates are inserted and the electrolyte is
introduced into the cells.
Moreover, my improved accumulator can be charged in much less time than those
hitherto employed.
Furthermore I greatly increase the capacity of the plates for occluding the gases
and correspondingly augment the storage power of the accumulator, and its capacity
for rapid charging and discharging, and at the same time obviate many of the
defects of the accumulators hitherto employed, such as the liability to disaggre-
gation of the active material and to the falling of the same from its support.
In making my improved electrodes, it is advantageous to employ, for the forcing
of the oxide into the metal plate, a bundle of needles or pointed rods having conical
points, and to drive the said needles simultaneously into the plate coated with the
oxide, by means of a light hammer or by other suitable means. By repeatedly
subjecting the plate to this operation a great number of times, the oxide of lead is
driven a considerable distance into the plate and the particles of metallic lead are
repeatedly displaced, thereby effecting a very intimate mixture of the same with the
particles of the oxide and bringing the particles of oxide into close contact with
those of the metallic lead by a kind of kneading action. Moreover the proportion
of particles of oxide to particles of lead gradually diminishes towards the middle of
the plate, thus grading or graduating the conductivity of the plate from its centre
to its sides. To more effectually ensure such graduation of the conductivity of
the plate, I sometimes provide interchangeable guards adapted to be placed upon
the bundle of needles or pointed rods so that the depth of the holes formed
thereby may be gradually diminished as the operation proceeds.
I find that a plate thus treated produces better results in respect of storage
capacity as well as in respect of freedom from buckling or warping of the plate.
The use of conical points affords the further advantage that any expansion of the
active material which may take place during the discharging of the accumulator
will simply cause outward or lateral movement or swelling of the said material in
the small couical cells formed by the driving of the needles into the plate, and will
not have any tendency to cause buckling or warping of the electrode. I find that
the finer the cells formed by the needles or points, the greater is the storage power
of the accumulator.
The manipulation of the plate coated with oxide can, if desired, be carried on in
the manner above mentioned until nearly the whole of the substance of the
electrode consists of a mixture of particles of oxide with particles of metallic lead.
As, however, an electrode so made would in itself have no efficient support or

page_text: conductivity, it is preferable to make the electrode with a layer of solid metal
between two layers of the mixture of lead oxide and metallic lead.
Dated the 13th day of August 1892.
D. YOUNG & Co.,
11 & 12, Southampton Buildings, London, W.C.,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements relating to Electric Accumulators or Secondary
Batteries, and to the Manufacture of Plates or Electrodes
therefor.
1, ARTHUR JAMES SMITH, of Kingston-on-Thames, in the County of Surrey,
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 :-
My invention relates to electric accumulators or secondary batteries and to the
manufacture of plates or electrodes therefor, and is chiefly designed to facilitate
and augment the electro-chemical actions and reactions which take place in the
accumulator, and thus increase the efficiency of the same in proportion to its
dimensions and weight as compared with the accumulators hitherto devised.
My said invention relates more particularly to accumulators or secondary
batteries of the kind or class wherein lead plates or electrodes are employed, and
wherein the storage of energy is effected by the de-oxidation of one of the lead
electrodes and the peroxidation of the other electrode. The electrodes for accumu-
lators of this kind or class are usually made by first coating or covering lead plates
with a suitable oxide of lead and then subjecting the same to the action of electric
currents in the accumulator. And in most of the endeavours hitherto made to
increase the efficiency and durability of accumulators of this kind or class, the aim
of the inventor has been to produce a lead plate or electrode having as large a
superficial area in proportion to its weight as is consistent with the proper strength
and durability of the said plate or electrode, in order to have as large a surface of
the metallic lead as practicable in contact with the active material. This result
has, in some measure, being obtained by making the electrodes of perforated plates
or gratings, the holes or cells of such plates or gratings being filled with the active
material.
It has also been proposed to make the electrodes by subjecting masses of lead
wire or the like to compression so as to produce what are termed "felted" plates,
which are then "formed" into the electrodes in the well-known manner, that is to
say, by causing the alternate de-oxidation and peroxidation of the electrodes by
repeated charging and discharging of the accumulator, with reversals of the
current if necessary.
It has also been proposed to make plates or electrodes by agglomerating under
pressure, mixtures of lead oxides with lead filings or the like, or with ammonium
sulphate and other substances.
I am aware also that it has been further proposed to produce lead plates of
great porosity by minutely puncturing one or both surfaces of sheets or plates
of lead by means of reciprocating needles, then oxidizing or chemically treating
the punctured plates, and then folding, pressing and re-puncturing them, these
operations being repeated as often as may be required to produce electrodes of
great porosity.
The result sought to be attained has always been to bring as much as possible of
the metallic lead into contact with the active material or to expose as large a
surface as practicable to contact with the electrolyte.
But I am not aware that any suggestions have heretofore been made for
facilitating and augmenting the electro-chemical actions and reactions in the

page_text: accumulator by the intimate intermingling and kneading of the particles of the
lead oxide with those of the metallic lead in the manner hereinafter described.
Now according to my invention, I take sheets or plates of lead of any suitable
dimensions and cover or coat the same with a suitable oxide of lead and cause the
particles of the said oxide, by means of a mechanical process or kneading, to
intermingle very intimately with those of the metallic lead on one or both sides of
the plate. I repeat these operations of covering or coating the plates with oxide
and driving or kneading such oxide into the metal, until the mixture of oxide with
metallic lead extends into the plate to a suitable depth, preferably leaving a
..portion or layer of the metallic lead solid or undisturbed in the middle of the plate,
or at one side of the plate as the case may be, to afford an efficient support for the
active material and a path of sufficient conductivity for the electric current.
In carrying my said invention into practice, find it advantageous to proceed as
follows, that is to say :-I first spread upon the lead plate, by any convenient
means, a layer of minium or other suitable oxide of, lead, preferably in the form of
dry powder, and, if desired, I moisten the said oxide with the electrolytic solution,
such, for instance, as sulphuric acid and water, I then force or knead the particles
of such oxide into the lead plate and thus intimately mix them with the particles of
the metallic lead, by repeatedly driving into the plate covered with the oxide, a
bundle of needles or pointed rods. More lead oxide is applied to the plate and
kneaded into the same from time to time as may be required. I treat in this
manner both the negative and the positive, or, in other words, the de-oxidized and
the peroxidized plates, and one or both sides of each plate as may be desired.
I do not confine myself to the use of any particular devices for driving the
pointed rods or needles into the plate to effect the intermingling or kneading of
the particles of oxide with those of the lead plate; I prefer, however, that the
desired result should be accomplished by percussion, so that the particles of oxide
and of metallic lead will be intermingled and kneaded in such a manner as to
ensure the cohesion of the greatest practicable number of the particles of oxide
with particles of the metallic lead.
In making my improved electrodes, it is preferable to employ, for the forcing or
kneading of the oxide into the metal plate, pointed rods or needles having conical
points, and to drive the said needles simultaneously into the plate covered or
coated with the oxide, by percussion by means of a light hammer or by other suitable
means.
The oxide should be applied as uniformly as practicable over the surface or
surfaces of the plate, and the driving or kneading of the oxide into the metal
should also be effected as uniformly as practicable. The most advantageous and
economical results are obtained by the use of a machine in which the pointed rods
or needles are attached to an oscillating or vibrating arm or to a reciprocating
holder, and the plate is fed regularly beneath the said needles, or the holder
carrying the needles is fed regularly relatively to the work. Plates or electrodes
of great efficiency and durability can be produced by such means, as the greater
the uniformity of the kneading in of the oxide, the greater will be the durability
of the plates or electrodes and the greater the storage capacity of the accumulator
in proportion to its weight.
By repeatedly subjecting the plate to the above described operations a great
number of times, the oxide of lead is driven a considerable distance into the plate
and the particles of metallic lead are repeatedly displaced and compressed or
condensed, and the particles of the oxide and those of the metallic lead are caused
to cohere by the kneading action above mentioned. Moreover the proportion of
particles of oxide to particles of lead gradually diminishes towards the imiddle of
the plate, thus grading or graduating the conductivity of the plate from its centre
to its surfaces. To more effectually ensure such graduation of the conductivity of
the plate, I sometimes provide interchangeable guards adapted to be placed upon
'the'bundle of needles or pointed rods so that the depth of the holes formed thereby
may ··be gradually diminished as the operation proceeds, Or the desired result is

page_text: attained by regulating the stroke or travel and percussive force of the needles or
pointed rods. I find that the finer the cells formed by the needles or points and
the oftener the kneading operation is repeated, the greater is the capacity or
storage power of the accumulator, and the power of the plates to resist flexure
or buckling under the influence of the charging and discharging of the
accumulator.
The manipulation of the plate can, if desired, be carried on in the manner above
described, until nearly the whole of the substance of the electrode consists of a
mixture of particles of oxide with particles of metallic lead. As, however, an
electrode so made would in itself have no efficient support or conductivity, it is
preferable to make the electrode with a layer of solid metal between two layers of
the mixture of lead oxide and metallic lead, by regulating the stroke or travel and
momentum of the kneading tool. It is desirable, in all cases, that the kneading of
the oxide into the metal should not be carried on to such an extent as to cause
disintegration of the electrode.
In the accompanying drawing I have shown, in- transverse section, a portion of
one of my improved plates or electrodes drawn to a greatly enlarged scile. In
this plate, there is a central conducting and supporting layer a of solid metal
having no oxide mixed therewith. On either side of this layer a there is a layer
or stratum 6 of metal into which particles of the metallic oxide have been kneaded
as above described, in such a manner as to graduate the conductivity of the plate,
that is to say, in first operating upon the lead plate with the needles, after a coating
or covering of oxide has been applied to the said plate, the needles are driven into
the plate as far as the point c; in the next operation, the needles are driven in only
The conical
as far as the point d, in the next only as far as the point e, and so on.
cells formed by the final puncturing of the plate with the pointed rods or needles
are then filled up with oxide of lead. Each side of the plate is treated in this
manner; therefore the metal on either side of the layer a has gradually more and
more oxide combined with it until at the surface there is a mixture of oxide of
lead with but a small proportion of metal, or there may be a thin layer of oxide on
the surface of the plate.
I find that a plate treated as above described produces better results in respect
of storage capacity as well as in respect of freedom from buckling or warping of
the plate, than any of the lead electrodes heretofore generally used in secondary
batteries.
The use of needles with conical points affords the further advantage that any
expansion of the active material or increase by discharge, which may take place,
will simply cause outward or lateral movement or swelling of the said material in
the small conical cells formed by the driving of the needles into the plate, and will
not have any tendency to cause buckling or warping of the electrode.
I wish it understood that in the term plate or electrode I include any lead
surface which will serve the purpose of my invention.
It will be seen from the foregoing description that I do not roll or fold the
punctured plates, but I repeatedly coat or cover the surface of the plate with the
oxide and drive or knead each coating or covering of oxide into the metal,
the density of the plate being thus increased.
manner, I am
By manufacturing the plates or electrodes in this
enabled to
dispense with the process hitherto practised of “forming" the electrodes by the
action of electric currents, my improved accumulator being ready for use as soon
as the said plates and the electrolyte are introduced into the cells.
Moreover, I greatly increase the capacity of the plates for occluding the gases,
and correspondingly augment the storage power of the accumulator and its capacity
for rapid charging and discharging as compared with the accumulators heretofore
devised, and at the same time obviate many of the defects of the accumulators
hitherto employed, such as the liability to disaggregation of the active material
and to the falling of the same from its support. Furthermore, by my improved

page_text: method or process, I can produce efficient and durable lead plates for accumu-
lators at a lower cost than is practicable by the methods or processes hitherto
adopted.
I can, if desired, use lead alloys instead of pure lead in the production of
my improved plates or electrodes. I find, however, that it is preferable to use
pure soft lead.
Instead of applying the oxide to the plate in the form of powder, I sometimes
form a coating of oxide on the plate by any well-known and suitable chemical
process.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I wish it understood that
I do not claim generally or irrespectively of my improvements herein set forth the
production of an electrode for a secondary battery or accumulator, by puncturing
a plate on one or both sides by means of pointed rods or needles; nor do I claim
the production of porous electrodes by minutely puncturing the surfaces of lead
sheets and oxidizing or chemically treating the punctured sheets and then rolling
the same and folding and repuncturing them; but I claim :-
First. The improved method or process of manufacturing a plate or electrode for
a secondary battery or accumulator, consisting in repeatedly covering or coating
a metal sheet or plate with the metallic oxide and driving or kneading such
oxide into the metal by means of pointed rods or needles, substantially as
herein before described.
Second. A plate or electrode for a secondary battery or accumulator, in which
the particles of oxide are kneaded into the metal by my improved method or process
herein before described.
Dated the 13th day of Ma- 1902
D. YOUNG & Co.,
11 & 12, Southampton Buildings, London, W.C.,
Agents for the Applicant.