Improvements in Secondary Batteries.
Year: 1892

page_text: Date of Application, 31st May, 1892
Complete Specification Left, 28th Feb., 1893-Accepted, 15th Apr., 1893
D
PROVISIONAL SPECIFICATION.
Improvements in Secondary Batteries.
We, EDWIN FREUND, of 40 Great Smith Street, in the City of Westminster,
Engineer, and LARS BRISTOL, of the same address, Electrician, do hereby declare
the nature of this invention to be as follows:-
Our invention relates to certain improvements in the construction of secondary
batteries, or accumulators, and the principal objects of our invention are, to provide
means for exerting a homogeneous resistance to the expansion of the battery plates,
the formation of a neutral space at the bottom of each cell, the employment of an
improved intermediate cover for preventing the escape of acid, and an improved
joint between the cells and the outer casing.
Our said improvements refer more particularly to the portable secondary batteries
described in the Specifications of the Patents granted to the aforesaid Lars
Bristöl, No. 9854 of July 6th 1888, No. 8456 of May 21st 1889, and No. 5329 of
March 5th 1891, but they are also applicable to secondary batteries, or accumulators
in general.
We have ascertained that the irregular and unrestricted increase in volume of
the active plates of secondary batteries during formation and charging, is detri-
mental to their capacity and durability. By inserting the plates into the cells in
such a manner, that during the process of forming and subsequently, a homogeneous
pressure or tension is brought to bear all over the plates, we obtain batteries of
greater specific capacity and reliability, and of much less weight than usual.
We attain the objects of our invention by means, which call for neither an
increase in the size of the battery, nor any special ratio between the width, length
and depth, while at the same time the dangerous effects of the fluid into which the
active plates dip are considerably decreased.
In constructing our improved batteries, the positive and negative plates in each
cell are slightly inclined towards each other, the top edges being further apart than
the bottom edges. Between the plates we insert a series of tapered staves, having
the same degree of taper as the space between the plates, their distances apart
being preferably about equal to the distance between the plates. These staves are
made of wood, ebonite, xyloid, glass, celluloid, vulcanised fibre, or any other
suitable non-conducting material, which will withstand the chemical action as
well as the occasional rise of temperature during charging and formation. The
staves exert a gentle and uniformly distributed pressure over the surfaces of the
plates.
In the case of plates kept in an inclined or horizontal position, prismatic or
cylindrical staves may be employed, and we then exert pressure upon the upper
plate, either by using a heavy plate, a grating, or some suitable mechanical
device.
We find it advisable to cover plates which consist of brittle material, such as
red-lead paste, with woven or other suitable material which is permeable by the
electrolyte, and which, by virtue of its tensile strength, equalises the pressure
exerted by the staves.
In place of the solid staves above described, various forms of elastic staves may
be employed, such for example as staves consisting of two strips united by elastic
listance pieces.
The strips may be parallel, or inclined to each other, and may be made in one
piece with the elastic distance pieces, or may be separate and kept apart by
ndependent spring pieces.
The staves may also be in the form of tubes, helical coils, or other suitable

page_text: hollow and elastic shape. Staves which touch the plates in curves or intersected
lines we find in practice to be less advantageous than straight staves.
It is known that the negative plates may be made lighter than the positive plates,
and we make use of this fact by employing plates of equal width, but unequal
depth, and the usual ratio of thickness, then by keeping the top edges of both
plates level, we create a neutral space at the botttom of the cell, where dirt and
dust from the plates may accumulate, without any danger of short circuiting. The
shorter plate is supported at the bottom by suitable steps, blocks, or staves of non-
conducting material.
The best effect is obtained from a cell by the plates being only so much less in
width than the compartment, as their expansion under the retarding influence of
the staves may require.
This expansion is about twice as great in the positive, as in the negative plate,
and amounts to about of an inch in 3 inches in the positive plate. Cells which
are wider than necessary to allow for this expansion, should be stopped off.
In many cases we strengthen the cells by means of plates, gratings, or boxes,
applied externally thereto, for the purpose of obtaining a resistance to balance the
pressure exerted from within by the staves and gases, it being important that this
inner pressure should be maintained.
The acid, which generally forms the electrolyte in secondary batteries, must
necessarily be prevented from destroying the arrangements made for the protection
of the cell walls, and we attain this object effectively in the following way. Over
the plates we place a cover of non-conducting material, and leave openings in it
through which the gases can escape and the electrolyte be renewed. The space
between this cover and the sealed outer cover of the battery forms a chamber,
wherein the escaping gases are forced to change their direction, because the openings
in the two covers are not arranged opposite to one another. This change of
direction delays the gas sufficiently to cause it to deposit the acid bubbles which it
contains, and no acid can therefore reach the openings or the safety plugs in the
outer cover.
To effectually protect the outer casing, or the supporting plates outside the cells
from the acid while it is being poured into the cells, we chamfer the outer top edges
of the cells, thus giving the acid-proof cement, or material employed to form the
top joint, a better hold and causing it to form a more effective joint by filling the
recess formed by such chamfer between the outer casing and the cell wall. Joints
formed in this way are in practice found to improve, whenever by reason of a
change in temperature or from other cause, the cell moves against the outer
casing.
Dated this 21+ 1... C
1000
AMBROSE MYALL,
21, Cockspur Street, London, S.W., Agent for the Applicants.
COMPLETE SPECIFICATION.
Improvements in Secondary Batteries.
We, EDWIN FREUND, of 40 Great Smith Street, in the City of Westminster,
Engineer, and LARS BRISTOL of the same address, Electrician, 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:-
Our invention relates to certain improvements in the construction of secondary
batteries, or accumulators, and the principal objects of our invention are, to
provide means for exerting a homogeneous resistance to the expansion of the
battery plates, the formation of a neutral space at the bottom of each cell, the
employment of an improved intermediate cover for. preventing the escape of acid
and an improved joint between the cells and the outer casing.

page_text: Our said improvements refer more particularly to the portable secondary
batteries, described in the Specifications of the Patents granted to the aforesaid
Lars Bristöl, No. 9854 of July 6th 1888; No. 8456 of May 21st 1889 and
No. 5329 of March 5th 1891; but they are also applicable to secondary batteries
or accumulators in general.
We have ascertained that the irregular and unrestricted increase in volume of
the active plates of secondary batteries during formation and charging, is detri-
mental to their capacity and durability. By inserting the plates into the cells in
such a manner that during the process of forming and subsequently, a homogeneous
pressure or tension is brought to bear all over the plates, we obtain batteries of
greater specific capacity and reliability and of much less weight than usual.
We attain the objects of our invention by means which call for neither an
increase in the size of the battery nor any special ratio between the width, length
and depth, while at the same time the dangerous effects of the fluid into which the
active plates dip are considerably decreased.
In the accompanying sheet of drawings, which forms part of this Specification,
Fig. 1 is a sectional elevation through the centre of a secondary battery
constructed in accordance with our invention, having vertical plates.
Fig. 2. is a similar sectional elevation through a central line at right angles to
that shewn in Fig. 1.
Fig. 3. is a sectional plan through A A in Fig. 1.
Fig. 4. is a sectional plan through B B in Fig. 2.
Figs. 5 represent, to an enlarged scale, in side and edge elevation and cross
section, one of the tapered staves shewn in Figs. 1, 2 & 4.
Figs. 6 are an edge elevation and cross section of a tapered stave of modified
form.
Fig. 7. is a sectional elevation through CC in Fig. 8 of a secondary battery
constructed in accordance with our invention, having horizontal plates.
Fig. 8 is a plan of Fig. 7.
Figs. 9. represent in side and edge elevation and plan a tapered stave of oval or
circular form.
Figs. 10. represent in side and edge elevation and plan, a tapered stave of cross
shaped section.
Figs. 11 to 18 inclusive, represent in side and edge elevation and plan various
forms of elastic staves.
Fig. 19 is an end elevation
Fig. 20. a side elevation, and
Fig. 21 a plan of a secondary battery having external supporting means arranged
in accordance with our invention.
Similar letters of reference denote similar parts throughout the drawings.
Referring first to Figs. 1, 2, 3, 4 and 5, D is the battery cell and E a box or
casing containing the said cell. F is the positive and H the negative plate. These
plates are slightly inclined towards each other, their top edges J, K, being further
apart than their bottom edges L, M. Between the said plates we insert a series of
tapered staves N, having the same degree of taper as the space between the plates,
the distance apart of the said staves being preferably about equal to the distance
between the plates. These staves are made of wood, ebonite, xyloid, celluloid
vulcanised fibre, glass, or any other suitable non-conducting material, which will
withstand the chemical action, as well as the occasional rise of temperature during
charging and formation. The staves may touch the bottom of the cell, or a small
space may be left under their ends. In Fig. 2 one of the staves is shewn touching
the bottom and the other two clear.
This combination of inclined plates and tapered staves has the effect of causing
the said staves to exert a gentle and uniformly distributed pressure over the surfaces
of the plates with the attendant advantages previously described.
In the case of plates placed in an inclined or horizontal position, prismatic or

page_text: cylindrical staves may be employed and we then exert pressure upon the upper
plates, either by using a heavy plate, a grating or some other suitable mechanical
device.
Figs. 6 shew a tapered prismatic stave and Figs. 9 a tapered stave which may be
of oval or circular form, and Figs. 10 a stave cross-shaped in section suitable for
the above purpose.
In Figs. 7 and 8 means are shewn for mechanically exerting pressure upon
horizontal plates, D is the cell, F the positive and H the negative plate, N are the
staves interposed between the plates, P is a heavy plate or grating placed on the
negative plate to which the required pressure is applied by a screw Q passing
through a cross bar R entered into openings S in the cell walls.
In batteries with horizontal plates, as above described parallel sided staves may
be employed, though in practice we prefer to employ the tapered form as they
admit of accurately adjusting the pressure to suit any variations in the form or
thickness of the plates, and when more than two plates are employed we prefer to
arrange the tapered staves in each row at an angle or opposed to the taper of the
staves in the row below, to equalize the pressure and keep the plates level.
We find it advisable to cover plates, which consist of brittle material, such as
red lead paste, with woven or other suitable material which is permeable by the
electrolyte, and which by virtue of its tensile strength equalizes the pressure
exerted by the staves.
In place of the solid staves above described, various forms of elastic staves may
be employed, such for example as staves consisting of two strips united by elastic
distance pieces. The strips may be parallel, or inclined to each other and may be
made in one piece with the elastic distance pieces, or may be separate and kept
apart by independent spring pieces. The said staves may also be in the form of
tubes, helical coils or other suitable hollow and elastic shape, but staves which
touch the plates in curves or intersected lines, we find in practice to be less
advantageous than straight sided staves.
Referring to the drawings illustrating various forms of elastic staves;
Figs. 11 shew a parallel stave formed of two straight strips a a united by sloping
distance pieces b, such distance pieces may be straight, as shewn in the upper plan
or may be circular, as shewn in the lower plan.
Figs. 12 shew a tapered stave formed of two straight strips a a united by
distance pieces b, formed with a double curve, such distance pieces may be either
broad or narrow, as shewn in the two plans.
Figs. 13 show a parallel stave formed of two straight strips a a united by
horizontally curved or semi-circular distance pieces b, the said pieces projecting
alternately on opposite sides, as shewn in the plan.
Figs. 14 shew a parallel stave formed of two straight strips a a united by
V shaped distance pieces b.
Figs. 15 shew a hollow or tubular stave which may be oval or circular in plan
and may if desired, be slotted down one side, as shewn at c in the lower plan.
In the examples given in Figs. 11 to 14 inclusive, the distance pieces and the
side strips are formed in one piece but in the examples shown in Figs. 16 to 18 the
said parts are separate.
In Figs. 16 a parallel stave is shewn having two straight strips a a formed with
grooves d on their inner sides. After the said strips have been placed in position in
the battery, semicircular elastic distance pieces b are pushed down the said grooves d
and exert the required pressure.
In Figs. 17 similar grooved side strips are shewn, with independent elastic
distance pieces b of a bow shape placed between them.
In Figs. 18 a tapered stave is shewn consisting of two side strips a a with a
single long distance piece e inserted between them. The upper plan shews such
a distance piece having a single, and the lower plan one with a double curve.
We wish it to be understood that the above described forms of elastic staves are

page_text: merely given as examples of this part of our invention and that many modifications
other than those shewn may be made in their design.
It is known that in batteries of this class, the negative plates may be made
lighter than the positive plates, and we make use of this fact in batteries with
vertical plates by employing plates of equal width, but unequal depth and the
usual ratio of thickness, then by keeping the top edges of both plates level, we
create a neutral space at the bottom of the cell on one side, where dirt and dust
from the plates may accumulate without any danger of short circuiting. The
shorter plate is supported at the bottom by steps or ledges moulded in the cell, or
by independent blocks or staves of suitable non-conducting material.
In Figs. 1 and 2 the negative plate H is shorter than the positive plate F and
the former is supported on a small block T preferably of non-conducting material,
so that the tops of the plates are level, while a neutral space V is created at the
bottom of the cell with the advantages above described.
On referring to Figs. 2, 3, 4, 7 and 8 it will be observed that the plates are
narrower than the cells, and it is found that the best effect is obtained from a cell
when the plates are only so much less in width than the compartment, as their
expansion under the retarding influence of the staves may require. This expansion
is about twice as great in the positive as in the negative plate, and amounts to
about of an inch in 3 inches in the positive plate. Cells which are wider than
necessary to allow for this expansion should be stopped off.
In many cases we strengthen the cells by means of plates, gratings, or boxes
applied externally thereto, for the purpose of obtaining a resistance to balance the
pressure exerted from within by the staves and gases, it being important that this
inner pressure should be maintained.
In Figs. 1 to 4 the strong external box or casing E gives the required resistance,
but in Figs. 19, 20 and 21 we show a cell D placed between two strong plates W,
the required resistance being given by the bolts X which unite the plates and
cause the cell to be gripped firmly between them.
The acid which generally forms the electrolyte in ordinary batteries must neces-
sarily be prevented from destroying the arrangements made for the protection of
the cell walls, and we attain this object effectively in the following way; over the
plates we place a cover Y, Figs. 1, 2 and 3, of non-conducting material and narrower
than the cell, so that openings Z Z are left at each side through which the gases
can escape and the electrolyte be renewed.
The space between this cover and the seated outer cover g of the battery
forms a chamber wherein the escaping gases are forced to change their direction,
because the opening in the safety plug in the cover is not opposite the
openings ZZ. This change of direction delays the gas sufficiently to cause it to
deposit the acid bubbles which it contains, and no acid can therefore reach the
opening or the safety plug in the cover g.
In place of making the cover Y narrower than the cell, as described, it may fit
the said cell and suitable openings be formed in it, care being taken that such
openings are not opposite any openings in the outer cover, for the reason above
mentioned. In all cases the cover Y is secured in position in the cell by means of
suitable cement at those of its edges which touch the cell walls, and such cover
therefore has the advantage of offering a resistance to the upward expansion of the
plates.
To effectually protect the outer casing, or the supporting box or plates outside
the cells from the acid, while it is being poured into the cells, we chamfer the top
edges of the said cells, as shewn at Figs. 1 and. 2, thus giving the acid proof
cement or material employed to form the top joint, a better hold and causing it
to form a more effective joint by filling the recess formed by such chamfer between
the outer casing and the cell wall. Joints made in this way are in practice found
to improve, whenever by reason of a change in temperature or from other cause,
the cell moves against the outer casing, as such movement has the effect of causing
the cement to creep further down between the cell and the casing.

page_text: 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. In a secondary battery, tapered staves made of suitable non-conducting
material and inserted between the positive and negative plates, to afford an
evenly distributed resistance to the expansion of said plates, substantially as
described.
2. In a secondary battery, elastic staves of suitable non-conducting material,
consisting of two straight strips united by suitably shaped elastic distance pieces,
said staves inserted between the positive and negative plates to afford an evenly
distributed resistance to the expansion of said plates, substantially as described.
3. In a secondary battery, elastic staves of suitable non-conducting material,
consisting of two straight strips and suitably shaped independent elastic distance
pieces inserted between them, said staves inserted between the positive and negative
plates to afford an evenly distributed resistance to the expansion of said plates,
substantially as described."
4. In a secondary battery, a positive plate and a negative plate said negative plate
made shorter than said positive plate and supported upon a step, ledge, or block to
create a neutral space at bottom of cell under said negative plate, substantially as
and for the purpose described.
5. In a secondary battery, a supplementary cover fixed in the cell over the
electrodes, a space between said supplementary cover and the outer cover, and
openings in or exterior to said supplementary cover, not opposite to any opening
or openings in said outer cover, substantially as and for the purpose described.
6. In a secondary battery, a cell having an exterior chamfer on its upper edges
to receive the cement forming the joint of the outer cover, substantially as and for
the purpose described.
7. In a secondary battery, the combination consisting of tapered or elastic
staves inserted between the positive and negative plates and a short negative
plate supported upon a step ledge or block to create a neutral space at bottom
of cell under said negative plate, all substantially as and for the purpose described.
8. In a secondary battery, the combination consisting of tapered or elastic staves
inserted between the positive and negative plates, a short negative plate supported
upon a step, ledge or block, a neutral space at bottom of cell under said negative
plate, a supplementary cover fixed over the electrodes a space between said cover
and the outer cover and openings in or exterior to said supplementary cover, not
opposite to any opening or openings in said outer cover, all substantially as and for
the purposes described.
9. In a secondary battery, the combination consisting of a short negative plate
supported upon a step, ledge or block to create a neutral space at bottom of cell
under said negative plate, a supplementary cover fixed over the electrodes, a space
between said cover and the outer cover, and openings in or exterior to said supple-
mentary cover not opposite to any opening or openings in said outer cover, all
substantially as and for the purposes described.
J
10. In a secondary battery the combination consisting of tapered or elastic staves
inserted between the positive and negative plates, a short negative plate supported
upon a step, ledge or block, a neutral space at bottom of cell, under said negative
plate, a supplementary cover fixed over the electrodes, a space between said cover
and the outer cover, openings in or exterior to said supplementary cover, not
opposite to any opening or openings in said outer cover and an exterior chamfer on
the upper edges of the cell to receive the cement of the top joint, all substantially
as and for the purposes described.
Dated this 20th 11
2000
AMBROSE MYALL,
21, Cockspur Street, London, S.W., Agent for the Applicants.