Improvements in the Manufacture of Electric Accumulators or Secondary Batteries.
Year: 1899

page_text: Date of Application, 1st Feb., 1899-Accepted, 4th Mar., 1899
Improvements in the Manufacture of Electric Accumulators or
Secondary Batteries.
I, JOHN GARFIELD HATHAWAY, of 57, Chancery Lane, in the County of London,
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 relates to the manufacture of electric accumulators or secondary
batteries of the kind or class wherein the electrodes proper are used as conductors
only, and the active material is not filled into the same.
The main object of my said invention is to produce a secondary battery of this
kind capable of being charged and discharged at a very high rate without injury,
and without loss of efficiency during the discharge. A further object of my said
invention is to provide a battery of reduced bulk, weight and cost in proportion
to its capacity and efficiency, as compared with those hitherto employed.
In secondary batteries in which the active material is confined by porous non-
conducting supports, the main cause of increase of internal resistance and decrease
of voltage during the discharge is the exhaustion of the acid from the electrolyte
which is diffused through the active material, more rapidly than it can be renewed
from the outside surrounding fluid by percolation through the said porous sup-
ports. A further cause is the accumulation of the gases generated, more especially
at the negative electrode, on discharge of the battery, which gases, unless their
free escape is in some way provided for, accumulate in the pores of the active
material and the porous supports, and exert an electromotive force which is
counter to that of the battery itself.
By my said invention I obviate the above-mentioned objections and disadvan-
tages.
In my improved accumulator or secondary battery, I employ rigid porous sup-
ports for the positive active material only, and I introduce the material which is
to become active negatively in such a manner that, in the operation of "forming"
the battery, the said negative material will be rendered self-supporting during
all subsequent conditions of use, and so that it will be freely and directly exposed
to the contact and action of the electrolyte without the interposition of an inert
porous mass through which the electrolyte must percolate in order to reach the
negative active material, and through which the gases generated at the negative
electrode during discharge must pass in order to escape from the cell.
For this purpose, in making my improved secondary battery, I provide a tem-
porary support for the active material on either side of the negative electrode.
composed of some suitable material which will be more or less rapidly destroyed
or eaten away by the acid of the electrolyte. This temporary support, which I

page_text: term a "manufacturing support," will sustain the said active material until the
latter is rendered self-supporting by the "forming" of the battery, and will
afterwards fall away from the said active material, leaving the outer surface of
the same directly exposed to the action of the electrolyte."
Therefore, in my improved secondary battery, when completely prepared for
use, the active material which has been applied in the form of paste or the like to
the negative electrode and rendered self-supporting by the
battery, has no external support such as would prevent or obstruct the free access
forming" of the
thereto of the electrolyte or the free escape of the gases generated at the negative
electrode.
I find it advantageous to provide each of the positive electrodes of my battery
with a number of pockets or perforations, which in use become filled with electro-
lyte and thus act as reservoirs thereof in close contact with the positive active
material, thereby assisting in the rapid diffusion of acid through the latter during
a heavy discharge.
In the accompanying drawing, I have shown how my said invention may be
conveniently and advantageously carried into practice.
Figure 1 is a vertical transverse section through one cell of a secondary battery
constructed according to my said invention.
Figure 2 is a horizontal section on the line A-B, Figure 1, showing one posi-
tive electrode and one negative electrode with their active material and supports
therefor.
Figure 3 is a face view of one of the "manufacturing supports" hereinafter
described.
Figure 4 is a similar view to Figure 1, and
Figure 5 a similar view to Figure 2, showing the parts after the "manufactur-
ing supports" have been destroyed or disintegrated by the acid of the electrolyte
In the secondary battery shown in the drawing, the positive active material is
supported by means of rigid porous support-plates a, which should be made of
kaolin or similar acid-resisting material containing no iron, and each of which is
preferably corrugated in one direction, so as to provide a number of parallel
grooves 6; these grooves are filled on one side of the support with positive
active material c, or material adapted to become active positively when the battery
is charged. The said supports thus filled are placed one on each side of a thin
metallic conducting-plate or electrode d. Red lead is commonly used as the
active material, and may be applied to the supports a in the form of a paste, in
a manner well-known in the art.
"
In applying the active material to the negative electrodes of my battery, I
prefer to employ a manufacturing support," by which term I mean a device
adapted to impart to the mass of red lead or other oxide with which it is combined
just enough strength and rigidity to cause it to hold together and remain in
proper relation to the other parts until the cell has been assembled and "formed,"
when the said support will be broken down or disintegrated by the acid; and I
combine the said oxide with this support in such a manner that, when it has
been reduced and the said support broken down or disintegrated, it will be exposed
to direct contact with the electrolyte on one side and with the negative conducting-
plate or electrode on its other side. I prefer to employ for this support a thin
piece e of. light, porous wood, having shallow projections or ribs f at its sides,
as shown in Figures 2 and 3, and provided with numerous holes g. The active
material is filled into the holes g and into the space between the projections or
ribs f until it is level with, or extends slightly beyond the level of the latter.
This manufacturing support may, however, be made in a variety of forms and of a
variety of materials which will be destroyed or eaten away by the acid but will
last until the active material is self-supporting, such as wood, plaster-of-Paris,
asbestos-cloth, and the like.
The negative conducting-plates or electrodes ; are made from suitable acid-
resisting conducting material, usually metallic lead, and, as they have no support-

page_text: ing function, they may be made very thin, thereby economizing in weight and
cost. These and the positive electrodes are cut to correspond in size with the
adjacent parts of the cell, an upwardly-projecting strip being left on each of
them to serve as a means of connection with each other and with the conducting
wires.
Since the positive active material of my battery is enclosed by its porous sup-
ports a, whereby the free circulation of the electrolyte is somewhat impeded, as
above explained, I prefer to provide my positive electrodes with a number of
pockets or perforations k, which in use become filled with the electrolyte and act
as reservoirs in direct contact and communication with the active material, ready
to supply the same with acid when the drain is unusually heavy, as in the case
of an excessively high discharge. It will be understood that these receptacles k
are not filled with the active material and do not in any sense assist in supporting
the same.
The negative electrodes j also may be provided with perforations, if desired,
but I prefer to leave these electrodes plain, since the electrolyte has free access
to the negative active materia!, and I can thus get sufficient conducting capacity
from thinner and lighter sheet lead.
In assembling the parts above described, a loaded support a is placed with
the face of the active material therein against one of the positive electrodes d,
and preferably with the grooves b vertical, in order to allow a free passage upward
for the escape of the gases generated by the action of the cell. A quantity of
material adapted to become active negatively and held in its manufacturing
support e, is placed against the ridges or ribs of the corrugated support a, and a
negative electrode is then placed against the opposite face of said material h,
so as to be in contact therewith over its entire surface. The parts thus assembled
form one complete couple, and as many of these couples as desired may be com-
bined in one cell, in a well-known "manner, with the positive and negative
electrodes alternating with one another, in which case each electrode except the
two outer ones will serve, as such, for two like masses of active material.
The couples may be held together by means of sheets or backs of glass, slate,
paraffined wood or equivalent acid-proof material placed against the opposite faces
of the combined couples and held in place by india-rubber bands m.
When the
cells are large, the bands m may be made of lead, and provided with small india-
rubber cushions beneath them. The structure is thus made integral and per-
manent in form, while at the same time it is capable of sufficient expansion and
contraction to satisfy the conditions of use.
33
It will be seen that the rigidity of my present battery and its resulting immunity
against the possibility of "buckling are secured by the rigid supports a, and
the said supports also serve to absolutely prevent short-circuiting between two
adjacent couples.
My present invention also provides for a much freer circulation of the electro-
lyte, and for the instant escape of the gases generated, which are produced for
the most part at the negative electrodes during discharge, and which pass directly
from the same into the empty vertical grooves 6 in the supports a, and thence
upward out of the cell.
The porous supports a may, if desired, be made in two or more sections, which
is advantageous in the case of large cells.
My battery above described is especially adapted to the needs of automobile
service, in which the conditions of use are exceedingly severe. A main requisite
in such service is lightness, hence the containing vessels and the quantity of
electrolyte must be as small as possible. A second requisite is the capacity to
endure without injury the shaking and jolting which is inevitable in such service.
Another is the ability to comply with sudden demands for an excessive current,
such as may be produced by the passing of the vehicle, when heavily loaded, from
a down grade to an up grade. Thus the electrolyte is liable not only to speedy
general exhaustion by reason of its small quantity, but also to sudden local ex-

page_text: haustion within the masses of active material, by reason of the sudden, heavy
discharges, the result being a rapid fall of potential and consequent loss of effici-
ency. I have found also that, if the proportion of acid in the electrolyte be
increased to compensate for the small quantity of the latter, then the supports
begin to be attacked, when made of pottery, and especially when they contain
iron, the alumina (and iron) being dissolved out of them to some extent, with
the result of impairing the strength and efficiency of the electrolyte.
By my present improvements I greatly diminish the difficulties above set forth,
as I secure lightness by the removal of the amount of porous material heretofore
necessary to form supports for the negative active material, at the same time
economizing in space and cost and reducing the liability of the electrolyte to
pollution from dissolved alumina, and also by perforating one or both of the
electrodes. I provide for the ready escape of gases, and secure free access of
the electrolyte to the active material, by exposing the negative active material
directly to the said electrolyte and by providing reservoirs for the electrolyte in
the positive electrodes. My battery also has rigidity combined with elasticity,
and is so compact that an increased amount of space is provided for the electrolyte
without increase in the total bulk of the entire battery. These and other advan-
tages will be sufficiently apparent to those skilled in the art without further
description.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I claim
is:
1. In a secondary battery, in combination with a negative electrode, a mass of
active material rendered self-supporting by the forming" of the battery and
having no external support such as would prevent free access of the electrolyte
to its outer surface or free escape of the gases generated during discharge, sub-
stantially as hereinbefore described.
2. The use, in a secondary battery, of one or more temporary or manufacturing
supports destructible by the acid of the electrolyte, for sustaining the active
material at the negative electrode until it is rendered self-supporting by the
"forming" of the battery.
3. The improved method of manufacturing a secondary battery, consisting in
assembling two or more couples each comprising a positive electrode, active
material arranged between the same and a porous support, a negative electrode and
active material arranged between the same and a temporary or manufacturing
support destructible by the acid of the electrolyte, and then rendering the nega-
tive active material self-supporting by forming" the battery, before the tem-
porary support or supports are destroyed by the acid, substantially as herein-
before described.
4. The employment, in a secondary battery, of a positive conducting plate or
electrode which is provided with perforations not filled with active material but
adapted to be filled with the electrolyte, and which is in contact with active
material held in one or more porous supports substantially as hereinbefore
described.
5. The combination of a perforated positive electrode, one or more porous sup-
ports containing active material in contact with the said electrode but not entering
the perforations thereof, a negative electrode, and a mass of active material in
contact therewith which has been rendered self-supporting by the “forming" of
the battery and one side of which is exposed directly to the electrolyte, for the
purposes above specified.
6. In a secondary battery, the combination of a perforated positive electrode, one
or more ridged or ribbed porous supports containing active material in contact
with the said electrode but not entering the perforations thereof, a negative elec-
trode, and a mass of active material in contact on one side with the said negative

page_text: electrode and on the other side with the ridges or ribs of one or other of the said
porous supports and having its surface next the said porous support exposed directly
to the electrolyte, substantially as hereinbefore described.
Dated the 1st day of February 1899
D. YOUNG & Co.,
11 and 12, Southampton Buildings, London, W.C., Agents for the Applicant.