U.S. patent number 3,775,188 [Application Number 05/175,475] was granted by the patent office on 1973-11-27 for method of multicell battery production using pocketed continuous strip.
Invention is credited to Kent V. Anderson, William D. Gerverdinck, John E. Oltman, Max Tronik.
United States Patent |
3,775,188 |
Oltman , et al. |
November 27, 1973 |
METHOD OF MULTICELL BATTERY PRODUCTION USING POCKETED CONTINUOUS
STRIP
Abstract
A method of constructing multicell batteries utilizes a
continuous web comprising a plurality of structurally connected
continuous Zones at least one of which comprises a continuous strip
of metal. Deposits of electrodes are placed along the Zones of the
continuous web after which the web is cut to structurally
disconnect the continuous Zones from each other. Pockets are then
indented in a Zone comprising a continuous strip of metal, the
indenting being done in a manner which results in the pocketed Zone
having the same relative longitudinal length after the indenting as
it had before the indenting. Finally, the pocketed Zone is collated
into an assembly of battery components which includes at least one
other continuous Zone from the web. The indenting may be preceded
by the cutting of a slit partially across the Zone to be pocketed,
in which case the width of the slits is increased but the center
lines of the slits remain in fixed relative longitudinal position
by the indenting action. The method is applicable both to webs
having metal and plastic laminations and to all metal webs.
Inventors: |
Oltman; John E. (Philadelphia,
PA), Anderson; Kent V. (Philadelphia, PA), Gerverdinck;
William D. (Philadelphia, PA), Tronik; Max
(Philadelphia, PA) |
Family
ID: |
22640363 |
Appl.
No.: |
05/175,475 |
Filed: |
August 27, 1971 |
Current U.S.
Class: |
29/623.3 |
Current CPC
Class: |
H01M
6/46 (20130101); Y10T 29/49112 (20150115) |
Current International
Class: |
H01M
6/42 (20060101); H01M 6/46 (20060101); H01m
001/02 () |
Field of
Search: |
;136/83R,111,175 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Walton; Donald L.
Claims
We claim:
1. A method of constructing multicell batteries utilizing a
continuous web comprising a plurality of structurally connected
continuous Zones, at least one of the Zones comprising a continuous
strip of metal, the method comprising the steps of:
a. cutting the continuous web so that the continuous Zones are
continuous strips which are structurally unconnected from each
other;
b. indenting pockets in a Zone comprising a continuous strip of
metal, each pocket being indented between a pair of predetermined
positions along the Zone, each pocket being formed while gripping
the continuous strip sufficiently to maintain the distance between
the pair of predetermined positions constant during the indenting
action; and,
c. collating the pocketed Zone into an assembly of battery
components which assembly includes at least one other Zone cut from
the web.
2. A method of constructing multicell batteries utilizing a
continuous web, the web comprising at least one Zone No. 1, at
least one Zone No. 2, and at least one Zone No. 3 which are
structurally connected together, at least one of the Zones
comprising a continuous strip of metal, the method comprising the
steps of:
a. placing intermittent deposits of electrodes along the continuous
web by
i. placing intermittent deposits of positive electrodes along one
side of each Zone No. 1.
ii. placing intermittent deposits of negative electrodes along one
side of each Zone No. 2, and
iii. placing intermittent deposits of positive and negative
electrodes along each Zone No. 3, each deposit of positive
electrode being on the other side of a Zone No. 3 from and
substantially opposite a deposit of negative electrode;
b. cutting the continuous web having the electrode deposits thereon
so that the Zones No. 1, No. 2, and No. 3 are continuous strips
which are structurally unconnected from each other;
c. indenting pockets in a Zone comprising a continuous strip of
metal, each pocket being indented between a pair of predetermined
positions along the Zone, each pocket being formed while gripping
the continuous strip sufficiently to maintain the distance between
the pair of predetermined positions constant during the indenting
action:
d. collating the continuous Zones No. 1, No. 2, and No. 3 so that
at least one Zone No. 3 is between a Zone No. 1 and a Zone No. 2,
so that the positive electrodes along Zone No. 1 and the negative
electrodes along Zone No. 2 are facing the inside of the collation,
and so that a deposit of positive electrode on one Zone is opposite
a deposit of negative electrode on an adjacent Zone;
e. placing a separator and electrolyte between each adjacent pair
of electrodes in the collation; and
f. sealing around the electrodes on the Zones.
3. The method of claim 2 in which Zone No. 1 comprises a laminate
of electrically conductive plastic and metal foil, Zone No. 2
comprises a laminate of electrically conductive plastic and metal
foil, and Zone No. 3 comprises electrically conductive plastic, the
electrodes being placed along the plastic sides of Zones No. 1 and
No. 2.
4. The method of claim 2 in which each of the Zones No. 1, No. 2,
and No. 3 comprises a metal foil the surfaces of which are
electrochemically non-reactive with respect to the electrodes and
electrolyte of the battery.
5. A method of constructing multicell batteries utilizing a
continuous web comprising a plurality of structurally connected
continuous Zones, at least one of the Zones comprising a continuous
strip of metal, the method comprising the steps of:
a. cutting the continuous web so that the continuous Zones are
continuous strips which are structurally unconnected from each
other;
b. cutting a pair of slits partially across the Zone comprising a
continuous strip of metal;
c. indenting a pocket between the slits in the slitted Zone, the
indenting being done in a manner which results in the width of the
slits being increased but the center lines of the slits remaining
in fixed relative longitudinal position by the indenting action;
and,
d. collating the pocketed Zone into an assembly of battery
components which assembly includes at least one other Zone cut from
the web.
6. A method of constructing multicell batteries utilizing a
continuous web, the web comprising at least one Zone No. 1, at
least one Zone No. 2, and at least one Zone No. 3 which are
structurally connected together, at least one of the Zones
comprising a continuous strip of metal, the method comprising the
steps of:
a. placing intermittent deposits of electrodes along the continuous
web by
i. placing intermittent deposits of positive electrodes along one
side of each Zone No. 1,
ii. placing intermittent deposits of negative electrodes along one
side of each of Zone No. 2, and
iii. placing intermittent deposits of positive and negative
electrodes along each Zone No. 3, each deposit of positive
electrode being on the other side of a Zone No. 3 from and
substantially opposite a deposit of negative electrode;
b. cutting the continuous web having the electrode deposits thereon
so that the Zones No. 1, No. 2, and No. 3 are continuous strips
which are structurally unconnected from each other;
c. cutting a pair of slits partially across the Zone comprising a
continuous strip of metals;
d. indenting a pocket between the slits in the slitted Zone, the
indenting being done in a manner which results in the width of the
slits being increased but the center lines of the slits remaining
in fixed relative longitudinal position by the indenting
action;
e. collating the continuous Zones No. 1, No. 2 and No. 3 so that at
least one Zone No. 3 is between a Zone No. 1 and a Zone No. 2, so
that the positive electrodes along Zone No. 1 and the negative
electrodes along Zone No. 2 are facing the inside of the collation,
and so that a deposit of positive electrode on one Zone is opposite
a deposit of negative electrode on an adjacent Zone;
f. placing a separator and electrolyte between each adjacent pair
of electrodes in the collation; and,
g. sealing around the electrodes on the Zones.
7. The method of claim 6 in which Zone No. 1 comprises a laminate
of electrically conductive plastic and metal foil, Zone No. 2
comprises a laminate of electrically conductive plastic and metal
foil, and Zone No. 3 comprises electrically conductive plastic, the
electrodes being placed along the plastic sides of Zones No. 1 and
No. 2.
8. The method of claim 6 in which each of the Zones No. 1, No. 2,
and No. 3 comprises a metal foil the surfaces of which are
electrochemically nonreactive with respect to the electrodes and
electrolyte of the battery.
Description
BACKGROUND OF THE INVENTION
U.S. Pat. No. 3,708,349 describes a method of constructing
multicell batteries utilizing a continuous web comprising a
plurality of structurally connected continuous Zones No. 1, No. 2,
and No. 3. At least one of the Zones of the web comprises a
continuous strip of metal. Intermittent deposits of positive
electrodes are placed along one side of each Zone No. 1;
intermittent deposits of negative electrodes are placed along one
side of each Zone No. 2; and intermittent deposits of positive and
negative electrodes are placed along each Zone No. 3, each deposit
of positive electrode being on the other side of a Zone No. 3 from
and substantially opposite a deposit of negative electrode. After
application of the electrodes the web is cut so that the continuous
Zones are structurally disconnected from each other. The Zones are
then collated into an assembly of battery components which includes
other continuous Zones from the web. Seals are then made around the
electrodes on the Zones.
In the collation and sealing together of the battery components one
of the Zones may remain in a plane configuration. In other Zones,
however, slight deflections must be made so that satisfactory seals
may be made around the electrodes. This necessary deflection
reaches its maximum in at least one of the outermost Zones in the
collation.
In order to maintain proper registration among the continuous Zones
during the collating and sealing steps it is necessary to maintain
precisely the relative longitudinal position of the electrodes
along each Zone with respect to the electrodes along the other
Zone. Errors along continuous strips may be cumulative, and the
accumulation of individually minor longitudinal errors in the
collation will, if repeated successively, result in such
misalignment that continued collation and sealing becomes
impossible.
With some materials which may be used in batteries, e.g., plastics,
fibrous materials, etc., and deflections required in these
materials may be achieved by the forces of the production machinery
used in the collation and sealing, and the related problem of
maintaining proper registration of these materials with respect to
other battery components may be resolved by the proper control of
tension. These solutions to production problems become
inapplicable, however, with battery components comprising
continuous strips of metal foils. With such foils it may be
necessary to produce any required deflections and to take any steps
necessary to maintain proper longitudinal registration before the
metal is included in the collation.
SUMMARY OF THE INVENTION
This invention concerns a method of constructing multicell
batteries which utilizes a continuous web comprising a plurality of
structurally connected continuous Zones at least one of which
comprises a continuous strip of metal. The continuous web is cut so
that the continuous Zones are continuous strips which are
structurally unconnected from each other. Pockets representing the
deflections required to permit collation and sealing are indented
in a Zone comprising a continuous strip of metal, the indenting
being done in a manner which results in the pocketed Zone having
the same relative longitudinal length after the indenting as it had
before the indenting to assure proper longitudinal registration of
the pocketed Zone with respect to other battery components. The
pocketed Zone is then collated into an assembly of battery
components which includes at least one other Zone cut from the
web.
Preferably intermittent deposits of electrodes are applied along
the continuous web before the web is cut to structurally disconnect
the Zones. The web is defined as comprising at least one Zone No.
1, at least one Zone No. 2, and at least one Zone No. 3 and the
electrodes are applied as follows: intermittent deposits of
positive electrodes are placed along one side of each Zone No. 1;
intermittent deposits of negative electrodes are placed along one
side of each Zone No. 2; and intermittent deposits of positive and
negative electrodes are placed along each Zone No. 3, each deposit
of positive electrode being on the other side of a Zone No. 3 and
substantially opposite a deposit of negative electrode. After the
web is cut, pockets are indented around the electrodes in those
Zones comprising metal foils which require deflections in the
collation.
The indenting action may be preceded by the cutting of a slit
partially across the Zone to be pocketed, in which case the width
of the slits is increased but the center lines of the slits remain
in fixed relative longitudinal position by the indenting
action.
The method is applicable both to webs having laminates of plastic
and metal and to all metal webs. In webs comprising laminates of
plastic and metal, the electrodes are preferably placed in contact
with the plastic rather than the metal. When the electrodes are
placed on a metal surface of the web, the surfaces of the metal
must be selected from metals which are electrochemically
nonreactive with respect to the electrodes and electrolyte of the
battery.
BRIEF DESCRIPTION OF THE DRAWINGS
As a prelude to a description of the drawings it should be remarked
that the thicknesses of the members shown in the drawings have been
greatly exaggerated for purposes of illustration. Thicknesses which
are typical of those which might actually be used will be given
together with other representative dimensions later in this account
of the invention.
FIG. 1 illustrates a web containing Zones No. 1, No. 2 and No. 3 in
which Zones No. 1 and No. 2 comprise laminates of electrically
conductive plastic and metal foils. The web, which is symmetrical
about its center line, contains enough Zones No. 1, No. 2 and No. 3
to permit the production of two four-cell batteries.
FIG. 2 illustrates the web of FIG. 1 after the deposits of
electrodes have been applied.
FIG. 3 illustrates an end or cross-sectional view of the web shown
in FIG. 2.
FIG. 4 shows Zone No. 1 after the web has been cut to structurally
disconnect the Zones from one another, after slits have been cut
into the Zone No. 1 and before pockets have been indented into Zone
No. 1.
FIG. 5 is a plan view of Zone No. 1 at the stage depicted in FIG.
4.
FIG. 6 shows Zone No. 1 after pockets have been indented into Zone
No. 1.
FIG. 7 is a plan view of Zone No. 1 at the stage depicted in FIG.
6.
FIG. 8 illustrates a continuous strip of separator material.
Patches of adhesive are impregnated into the strip, each patch
being in the form of a closed loop. Electrolyte is impregnated into
the area of the separator strip inside each loop.
FIG. 9 illustrates the pocketed Zone No. 1 being assembled into
multicell batteries.
FIG. 10 illustrates one of the multicell batteries made as shown in
FIG. 9 after that battery has been cut from the continuous
Zones.
FIG. 11 illustrates a cross-section of the multicell battery shown
in FIG. 10.
FIGS. 12, 13, 14 and 15 illustrate alternatives to the web
configuration shown in FIG. 3.
FIG. 16, which represents an alternative to the construction shown
in FIG. 11, illustrates a battery in which both outer Zones of the
battery comprise metal foils in which pockets have been
indented.
FIG. 17 shows a web of all metal analagous to the web of metal and
plastic laminate shown in FIG. 2.
FIG. 18 illustrates an end or cross-sectional view of the web shown
in FIG. 17.
FIG. 19, which is analagous to FIG. 11, illustrates a cross-section
of the multicell battery made from the web shown in FIG. 17.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
It should be remarked that the thicknesses of the members shown in
the drawings have been greatly exaggerated for purposes of
illustration. Thicknesses which are typical of those which might
actually be used will be given together with other representative
dimensions later in the description of this invention.
For simplicity the description of the invention will be divided
into four sections. Section 1 will describe the method of making
batteries using a web comprising composite continuous strips of
plastic and metal foil which is the subject of U.S. Pat. No.
3,708,349. Section 2 will concern the relationship of this
invention to the process described in Section 1. Section 3 will
describe the application of this invention to an all metal web.
Section 4 will be directed to the materials which may be used with
the processes described in the other sections.
SECTION 1: WEB COMPRISING LAMINATION OF METAL AND PLASTIC
This section will describe how the present invention may be used
with the web comprising a lamination of metal and plastic which is
the subject of U.S. Pat. No. 3,708,349.
FIG. 1 illustrates a web 7 which contains enough Zones No. 1, No. 2
and No. 3 to permit the production of two four-cell batteries. The
web comprises one continuous strip of electrically conductive
plastic 50 and three other continuous strips of metal foil joined
thereto, one of these three strips being a metal 60 which is
situated in the center of the plastic 50 and the other two strips
also being metals 70 which are joined to the side of the plastic
opposite metal 60 and which are situated near the edges of the
plastic. While the edges of the metal foils 60 and 70 could extend
to the edges of their respective Zones, it is preferable to recess
them slightly, e.g., 1/16 inch from each edge of the Zone to
facilitate cutting or slitting the web apart. While FIG. 1 uses
dashed and center lines to demarcate the boundaries of Zones No. 1,
No. 2 and No. 3, it should be understood that those lines are used
in the drawings for purposes of illustration only and no such lines
are required on an actual web. It will be seen that Zone No. 1 is
defined as a composite of a strip of plastic 50 and a metal foil
60, Zone No 2 is defined as a composite of a strip of plastic 50
and a metal foil 70, and that Zone No. 3 is defined as a continuous
strip of plastic 50. In the web 7 shown in FIG. 1, the plastic 50
components of Zones No. 1, No. 2 and No. 3 are all undivided
portions of one wide sheet of plastic.
The construction of multicell batteries begins by placing
intermittent deposits of positive electrodes 20 along the plastic
side of Zone No. 1, by placing intermittent deposits of negative
electrodes 30 along the plastic side of Zone No. 2, and by placing
intermittent deposits of positive and negative electrodes 20 and 30
respectively along each Zone No. 3 so that each deposit of positive
electrode 20 is on the other side of the Zone No. 3 from and
substantially opposite a deposit of negative electrode 30.
Illustrations of the web 7 after the electrodes have been so
deposited are shown in FIGS. 2 and 3. It will be noted that in all
cases the electrodes are narrower than and are centered within the
Zones onto which they were applied, thus leaving perimeters on the
Zones around the electrodes which will be used in the subsequent
sealing step.
After the electrodes have been applied the continuous web 7 is cut
so that the Zones No. 1, No. 2 and No. 3 are continuous strips
which are structurally unconnected from each other. The continuous
Zones No. 1, No. 2 and No. 3 are then collated so that at least one
Zone No. 3 is between a Zone No. 1 and a Zone No. 2, so that the
positive electrodes along Zone No. 1 and the negative electrodes
along Zone No. 2 are facing the inside of the collation, and so
that a deposit of positive electrode on one Zone is opposite a
deposit of negative electrode on an adjacent Zone. A separator and
electrolyte would be placed between each adjacent pair of
electrodes in the collation and then the Zones would be sealed
together around and between the electrode deposits.
An illustration of a separator strip 40 which might be used is
shown in FIG. 8. The continuous strip separator material 40 has
patches of electrically nonconductive adhesive 100 impregnated
therein, with each patch being in the form of a closed loop inside
of which is an area 42 of separator material which contains
electrolyte. By impregnating the adhesive patches into the
separator material first and then adding the electrolyte to the
resultant enclosed areas 42, the electrolyte can be confined within
those areas and prevented from migrating along the separator strip
40 while at the same time a better, more thorough adhesive
impregnation can be obtained in the separator which results in a
superior seal in the assembled battery. Such a concept is further
described and claimed in U.S. Pat. No. 3,701,690. As one
alternative to the technique just described, adhesive patches could
be impregnated into the continuous strip of separator material 40
after the electrolyte has been added to the separator. Another step
which could be used instead of but which is preferably used in
conjunction with the adhesive impregnations in the separator is to
apply patches of adhesive 101 around the electrodes on Zones No. 1,
No. 2 and No. 3 as shown in FIGS. 2, 3 and 5. By themselves these
patches 101 would penetrate the separator strips and produce the
desired seals when the collation of Zones and separator strips was
pressed together; a sealing technique of this latter nature used in
the production of single cell batteries is illustrated in U.S. Pat.
No. 3,494,796. It is preferred, however, to use the patches 101 in
combination with the adhesive patches in the separator strip; it
has been found that this combination produces a better seal than
the other alternatives discussed above which utilize a separator
strip.
FIG. 2 also shows a series of dashes 180 being placed across the
web between the electrodes. These dashes, which are purely
optional, may serve as registration devices used in the production
machinery. Such registration marks should be applied to the web
before the web is cut.
The collation of Zones No. 1, No. 2 and No. 3 and of the preferred
separator strip after the web 7 has been cut to structurally
disconnect the Zones is illustrated in FIG. 9. As shown in FIG. 9,
the electrolyte impregnated areas 42 inside the patches of adhesive
100 in the separator strip 40 are positioned so that the
impregnated areas are between and overlay a positive electrode on
one Zone and a negative electrode on an adjacent Zone. The adhesive
patches 100 register or mate with the corresponding adhesive
patches 101 on the perimeters of the Zones surrounding the
electrodes. After the desired number of Zones No. 3 and separator
strips 40 have been collated between Zones No. 1 and No. 2 the
sealing step is performed. Depending upon the particular sealant
100 which is used, the sealing may be achieved by the application
of heat and/or pressure, although other satisfactory sealing
techniques may also be used. The resultant multicell batteries may,
if desired, be left structurally connected together after the
sealing so as to form a chain of multicell batteries which are
electrically connected in parallel. Alternatively the collated,
sealed continuous strips may be cut so that the resultant multicell
batteries are structurally and electrically disconnected from each
other; such a discrete battery 5, illustrated in FIG. 10, may be
obtained by cutting along the collated sealed continuous strips at
the dashed, imaginary "cut" lines shown on the separator strip 40
in FIGS. 8 and 9 with an electrically nonconductive cutting
instrument such as a saphire or ceramic knife, by laser beams or by
other suitable techniques. The cutting must be done in a manner so
as to avoid producing undesired internal electrical paths within
the battery, e.g., so as to prevent the electricity conductive
plastic 50 from one Zone from coming into contact with the plastic
50 of another Zone. A portion of the assembled battery is shown in
magnified cross-section in FIG. 11.
If desired the web 7 can be constructed so that the finished,
assembled battery has one of its terminals wrapped around its edge
which overlays the terminal on the opposite side. For some
applications of the batteries it may be desirable to have both
terminals on the same side of the battery. Many different
modifications can be made in the web to achieve this same net
result. One such modification is represented by dashed lines and
the designation 70E which appear in FIGS. 1, 2 and 3. This optional
extension 70E of the metal foil 70 projects beyond the edge of the
plastic component of Zone No. 2, is wrapped around the edge of the
collation and overlays the metal 60 of Zone No. 1. An electrical
insulator must be interposed between the extension 70E and the
composite Zone over which it is overlaid; while a nonconductive
adhesive 100E of the same material as adhesive 100 is shown in the
drawings for purposes of illustration, other nonconductive securing
materials including a variety of hot melts used in the dry battery
industry may be used to also secure the extension to the underneath
Zone, and other nonsecuring nonconductors such as papers, felts, or
films may be interposed between the extension and the Zone. The
resultant product having the "wrapped around" terminal is further
described, illustrated, and claimed in U.S. Pat. No. 3,734,780. The
particular construction shown in FIGS. 1, 2 and 3 utilizes the
relatively good longitudinal conductivity of the metal as compared
with the conductive plastic to minimize the power losses in
conducting current around the edge of the battery. A battery with
the "wrapped around" terminal adhered to the negative rather than
the positive end of the battery can be obtained with the web 7 of
FIGS. 1 and 2 (including metal extensions 70E) by transposing the
positive and negative electrodes and therefore in effect
transposing Zones No. 1 and No. 2 from the positions shown in FIGS.
1 and 2; such transposition results in the metallic strip of Zone
No. 1 being wider than and extending beyond the edge of the plastic
strip of Zone No. 1 and being adhered to the metal of Zone No. 2.
Another modification of the web which results in the "wrapped
around" electrode is the extension of the plastic-metal laminates
at the edges of the web, rather than the extension of just the
metal 70E as shown in FIGS. 1 and 2. Other modifications of the web
which permit the construction of "wrapped around" terminals will be
given below in the accounts of alternative web configurations or
designs.
While the web 7 which is used with this invention must have at
least one Zone No. 1, at least one Zone No. 2, and at least one
Zone No. 3, there are numerous web configurations which meet these
requirements and which can be used with this invention. FIGS. 12
through 15 illustrate a few of these many different web
configurations.
The web 7 shown in FIG. 12 differs from those shown in FIGS. 1, 2
and 3 by having five Zones No. 3 on each side of the center line.
Each half of this web contains enough Zones to permit the
construction of a six cell battery according to the invention.
The web 7 shown in FIG. 13, which is likewise symmetrical about its
center line, contains enough Zones to permit the construction of
four four-cell batteries. An optional modification of the web 7,
which could be made if a "wrapped around" terminal of
metal-conductive plastic composite is desired in the finished
batteries, is also illustrated. As part of this optional modication
the plastic 50 and metal 60 could be extended at both edges of the
web, as shown by dashed extensions 50E and 60E, respectively. An
additional aspect of the modification is illustrated near the
center of the web by the letter "x", which represents the distance
from the edge of the positive electrode 20 to the web centerline or
the edge of Zone No. 1; this distance "x" could be increased to
include a segment of plastic 50 metal 60 laminate equal in width to
50E nand 60E.
FIG. 14 illustrates a web 7 which is symmetrical about its center
line. On each side of the center line is one Zone No. 1, one Zone
No. 2, and one Zone No. 3; each half of this web contains enough
Zones to permit the construction of a two cell battery. The web
contains six Zones but only a single strip of electrically
conductive plastic 50. As is true with the web shown in FIG. 1, the
web of FIG. 14 has a metal strip 60 which is cut down the middle
when the web is cut into unconnected Zones. The optional extensions
70E of metal strips 70 are also shown by dashed lines in FIGS.
14.
A very simple configuration of the web 7 having the essential
requirements is shown in FIG. 15. That web has one Zone No. 1, one
Zone No. 2 and one Zone No. 3, is symmetrical about its center
line, and contains enough Zones to permit the construction of one
two-cell battery. The web could, of course, be modified if desired
to permit the resultant battery to have a "wrapped around" terminal
of either metal or metal-conductive plastic composite.
It was mentioned as a prelude to the description of the drawings
that the thicknesses of the battery components shown in the
drawings have been greatly exaggerated for purposes of clear
illustration. This invention may be used and is particularly useful
in the construction of very thin, flat multicell batteries. The
dimensions associated with the web, electrodes and separator
illustrated in FIGS. 1 through 3, taken from an actual production
line design, will serve to illustrate. Referring to FIGS. 1 through
3, the continuous strip of electrically conductive plastic 50 was a
total of 271/2 inches wide and 2 mils (thousandth of an inch)
thick; of this total width, each of the two Zones No. 1 was 23/4
inches wide, each of the two Zones No. 2 was 23/4 inches wide, and
each of the six Zones No. 3 was 23/4 inches wide. The metal strip
60 shown in the center of the web was steel and was 53/8 inches
wide. The metal strips 70 at the two outer edges of the web were
also steel and were each 33/4 inches wide, of which 2 11/16 inches
width was joined to the conductive plastic of Zones No. 2 while the
remaining 1 1/16 inches of metal extended outward as extension 70E
to provide for a "wrapped around" terminal. Each of the metal
strips 60 and 70 was 11/2 mils thick. The electrode deposits 20 and
30, which were centered in each of the Zones, were approximately 2
1/16 inches wide. The electrode deposits, which might be as much as
20 to 25 mils or more but would typically be 10 mils or less in
thickness, were approximately 2 15/16 inches long (along the length
of the Zone) and a space of about 5/8 inches clear space was
provided between the nearest edges of consecutive electrodes. After
the electrodes were applied to the web the web was cut by steel
slitting wheels to disconnect the Zones from one another. The
separator strips 40, which were made from nonwoven polyester
fabric, were 3 1/2 mils thick and had areas 42 which were centered
about and approximately the same horizontal dimensions as the
electrodes.
As is shown in FIG. 11, each plastic, metal and separator member of
the assembled battery must be slightly longer and must be deflected
slightly more than the other plastic, metal, and separator members
beneath it. This slight increase in length of the separators 40 and
the plastic members 50 of Zones No. 3 may be achieved by providing
enough tension in those members to stretch them by the required
amounts. The deflections required in these materials to attain the
contour shown in FIG. 11 may be achieved by the forces of the
production machinery used in the collation and sealing. The
plastic-metal laminate of Zone No. 1, which must be increased in
length the greatest amount as shown in FIG. 11, may be indented or
pocketed into the desired shape prior to the collating and sealing
steps.
An alternative to the cross-section shown in FIG. 11 appears in
FIG. 16. In the alternative illustrated in FIG. 16 the middle Zone
of the collation, a Zone No. 3, is not deflected at all while the
remaining Zones on each side of the middle Zone are deflected. With
this construction there would be a need to pocket both Zone No. 1
and 2 before assembling them into the collation, since both of
those Zones contain continuous strips of metal.
The method by which these pockets may be produced, which method is
the subject of this application, will be described in the following
section.
SECTION 2: THE POCKETING METHOD
In order to maintain proper registration among the continuous Zones
during the collating and sealing steps it is necessary to maintain
precisely the relative longitudinal position of the electrodes
along each Zone with respect to the electrodes along each other
Zone. Stated another way, the indenting must be done in a manner
which results in the pocketed Zone having the same relative
longitudinal length after the indenting as it had before the
indenting. Errors along continuous strips may be cumulative, and
the accumulation of individually minor longitudinal errors in the
collation will, if repeated successively, result in such
misalignment that continued collation and sealing becomes
impossible.
The problem, therefore, is to provide the necessary deflection in a
Zone comprising a continuous strip of metal while at the same time
maintaining the relative longitudinal length of the Zone containing
the continuous metal strip.
The problem is solved by this invention in a manner which is best
illustrated in FIGS. 4 through 11. After the electrodes have been
placed onto the web and the web has then been cut into structurally
unconnected Zones, Zone No. 1 which contains the continuous strip
of metal is indented in a manner which maintains the relative
longitudinal length of that Zone. To accomplish this result it may
be desireable to cut a slit partially across the Zone and between
each consecutive pair of electrodes along that Zone. Zone No. 1
with such slits 165 therein is shown in FIGS. 4 and 5. As shown in
FIG. 5, the slits 165 have a width Z.sub.1 before the pockets are
indented, with representative dimensions of Z.sub.1 being from
about 0.060 inches to about 0.062 inches. The slits 165 may be
produced by a composite die which cuts slits by a punch and die
arrangement and pockets between the slits in the same stroke with
an undersize punch in a die. The longitudinal dimension along Zone
No. 1 between the pair of predetermined positions represented by
the center lines of the slits is designated by "y", with a
representative magnitude of "y" being approximately 3.56 inches
(the sum of 2 15/16 and 5/8 inches, as given in the preceding
section). It should be pointed out that as used herein, the word
"slit" has the general meaning given to that term by Webster's
dictionary, i.e., a long incision or a long, very narrow opening;
the term "slit" is not meant to imply any limitation on the process
or method of making the long incisions, and different techniques
sometimes referred to in certain industries as "slitting",
"piercing", "punching", and others may all be used to produce the
long, very narrow openings.
Referring now to FIGS. 6 and 7, which show Zone No. 1 after the
pockets 175 have been indented, as well as to FIGS. 9, 10, and 11,
it will be evident that the total length along Zone No. 1 as
measured by following the pocketed contour down the middle of that
Zone is in excess of dimension "y" but that the longitudinal
distance along Zone No. 1 (disregarding the pocketed contour)
between the center lines of consecutive slits has been maintained
at dimension "y". This is accomplished by obtaining the stretching
which results from the pocketing in the region of Zone No. 1
between the edge of the electrode and center line of the slit. As a
result of this stretching the width of the slits 165 is increased
from dimension Z.sub.1 to dimension Z.sub.2, as shown in FIG. 7,
with the increase in width typically being from about 0.002 inches
to about 0.007 inches with pocket depths ranging from about 0.030
inches to about 0.045 inches, respectively.
The pocketing can be performed without first slitting Zone No. 1 if
the Zone can be stretched sufficiently while simultaneously
maintaining the distance "y" constant. Unfortunately some of the
mechanisms used to produce pocketing do not consistently grip the
metal strips in such a manner as to accomplish this result; instead
there is a slight slippage of the Zone within the mechanism during
the indenting action which results in the distance "y" being
reduced rather than being held constant. Where this problem is
encountered the slits 165 are useful, for they permit the slippage
of the Zone within the indenting mechanism to be offset by a
stretching or elongation of the Zone outside the indenting action,
with the net result that the desired pocket is achieved while the
dimension "y" is held constant.
One other observation should be made to complete the discussion of
the pocketing. The indenting mechanism used to produce the pockets
must be stationary with respect to the Zone containing the
continuous metal strip when the pocketing is occurring. One way in
which this result can be obtained is through the use of indenting
mechanisms which do not travel longitudinally in the direction of
the Zone's travel; in that case a segment of the Zone is brought to
a standstill just long enough to undergo pocketing, with take-up
loops before and after the pocketing station letting out and taking
up, respectively, the continuous Zone as needed for the other
production steps. An alternative way to achieve the pocketing is
with the use of a rotating, endless belt moving at such a speed
that each pocketing mechanism is in a fixed longitudinal position
with respect to a segment of the Zone while that segment is being
pocketed.
SECTION 3: THE ALL METAL WEB
Sections 1 and 2 described how the present invention may be used
with webs comprising a combination of plastic and metal. This
Section will describe the relevance of the invention to an all
metal web. FIGS. 17, 18, and 19 will be referred to in this
Section.
FIG. 17 shows an all metal web which is analagous to the one shown
in FIG. 2. Its cross-section, shown in FIG. 18, is analagous to the
cross-section shown in FIG. 3. A single metal foil 60 is used, and
extensions 60E may be provided if the "wrapped around" terminal is
desired in the finished battery.
The cross-section of the finished battery made from the web
illustrated in FIGS. 17 and 18 is shown in FIG. 19. Note that FIG.
19 is analagous to FIG. 11. Note, however, that in FIG. 19 each of
the Zones contains a portion of the continuous strips of metal and
that only one of these Zones, Zone No. 2, does not require
pocketing. Note also that the remaining Zones, Zones No. 3 and Zone
No. 1, all require pocketing and each by a unique amount.
Starting with the web shown in FIGS. 17 and 18, the Zones could be
assembled into a battery having a cross-section analagow to that
shown in FIG. 16. In that case one of the Zones No. 3 would require
no pocketing, while the remaining Zones -- Zone No. 1, Zone No. 2
and two Zones No. 3 -- would require pocketing, the amount of the
deflection pocketed into Zone No. 1 being equal to that pocketed
into Zone No. 2 and the amounts pocketed into the two Zones No. 3
being equal to each other.
The drawings and the accounts given above in Sections 1 and 2 in
this Section thus illustrate the principle that the initial
continuous web comprises a plurality of structurally connected
continuous Zones; that at least one of these Zones comprises a
continuous strip of metal; that the continuous web is cut so that
the continuous Zones are structurally unconnected from each other;
that pockets are indented in at least one Zone comprising a
continuous strip of metal, with the indenting being done in a
manner which results in the pocketed Zone having the same relative
longitudinal length after the indenting as it had before the
indenting; and that the pocketed Zone is collated into an assembly
of battery components which assembly includes at least one other
Zone cut from the web.
SECTION 4: THE MATERIALS
The process of this invention may utilize a wide variety of
materials.
The electrically conductive plastic used in the continuous carrier
strip 50 described in Section 1 may be produced by casting,
extrusion, calendaring, or other suitable techniques. The
conductive plastics may be made, for example, from materials such
as polymers loaded with electrically conductive particles and
containing various stabilizers and/or plasticizers. The conductive
particles may be carbonaceous materials such as graphite or
acetylene black, or metallic particles may also be used. Polymers
which by themselves are sufficiently conductive may also be used.
The conductive plastic, whether loaded or unloaded, must be made
from a composition which is compatible with other components of the
battery. For batteries using LeClanche and moderately concentrated
alkaline electrolytes, the conductive plastic may be made for
example, from materials such as polyacrylates, polyvinyl halides,
polyvinylidene halides, polyacrylonitriles, copolymers of vinyl
chloride and vinylidene chloride, polychloroprene, and
butadiene-styrene or butadiene-acrylonitrile resins. For batteries
using strongly alkaline electrolytes, polyvinylchloride and
polyolefins such as polyethylene and polyisobutylene may be used in
the preparation of the conductive plastic. For batteries using acid
electrolytes such as sulfuric acid polyvinyl halides, copolymers of
vinyl chloride, and vinylidene chloride may be used.
The metal foils used in the production of Zones No. 1 and No. 2
described in Sections 1 and 2 may be made from such metals as
steel, aluminum, lead or zinc. These metals are relatively
inexpensive, they are good electrical conductors, and they can be
obtained in foils of extreme thinness which are substantially free
of pinholes. The foils of these metals can be purchased in rolls of
great length and thus are well suited for use in high speed,
continuously operating laminating machinery. These metals may also
be laminated to some conductive plastics by the application of heat
and pressure without requiring any intermediary adhesives between
the layers, or they can be laminated using intermediate adhesives.
It should be pointed out that while it may be common in some
industries to imply a maximum thickness limitation whenever the
terms "foil" or "metal foil" are used, no such limitation is
intended as those terms are used herein.
The positive electrodes 20 may each comprise particles of
electrochemically positive active material contained in and
dispersed throughout a binder matrix. The positive active material
conventionally is divided ito tiny particles so as to increase the
rate at which the electrochemical reactions can occur by increasing
the surface area where they occur. The binder increases the
electronic conductivity of the electrode, increases the structural
integrity within the positive electrode, and adheres the positive
electrode to the carrier strip. Since electrolyte must have access
to the surface of the active material particles, the electrode must
be made sufficiently porous so that the electrolyte may diffuse
throughout the electrode rapidly and thoroughly. Preferably the
pores in the electrode are produced by the evaporation of liquid
during the construction of the electrode; the evaporating liquid
may be part of a dispersion binder system in which the solid binder
contained in the finally constructed electrode comprises tiny
particles of binder material dispersed throughout and not dissolved
in the liquid while the electrode is being constructed, or the
evaporating liquid may be part of a solution binder sysem in which
the solid binder contained in the finally constructed electrode is
dissolved in the liquid which is later evaporated. The porosity of
the positive electrodes may be increased as the discharge rate
desired in the battery is increased. Electrodes may also be
constructed using various combination of the dispersion and
solution systems. Alternatively, the pores might be produced by the
dissolving of a solid which was present during construction of the
electrode or by passing gases through or generating gases within
the electrodes at controlled rates during electrode construction.
The positive electrodes 20 may, and preferably will, also contain
amounts of a good electrical conductor such as carbon or graphite
to improve the electrical conductivity between the active material
particles themselves generally being relatively poor conductors of
electricity. The conductivity of the active material particles
together with the conductivity of the binder itself will influence
the amounts of conductors added to the electrode. The electrodes 20
may also contain if desired small amounts of additional ingredients
used for such purposes as maintaining uniform dispersion of active
materials particles during electrode construction, aiding the
diffusion of electrolyte through the pores of the finally
constructed electrodes, controlling viscosity during processing,
controlling surface tension, controlling pot life, or for other
reasons.
The negative electrodes 30 may comprise spray or vapor deposits of
metals or may comprise tiny particles of metals contained in and
dispersed throughout a binder matrix. If the negative electrodes
utilize a binder matrix, in general the same considerations
regarding that matrix apply to the negative electrodes as do for
the positive electrodes except that no electrical conductor may be
needed to achieve desired electrical conductivity between the
active material particles since the negative active materials are
generally better conductors than are the positive materials. When
the negative electrodes utilize a binder matrix, the binder system
need not be the same as the one used in the positive electrodes,
and even if it is the proportions of binder, active material
particles, and other ingredients in the negative electrodes may
have a different optimum than the proportions of analagous
ingredients in the positive electrode. When the negative electrodes
20 are deposited onto the web in the form of liquid dispersions of
active materials and binder, the electrodes should be dried before
being further processed. The initial porosity of the negative
electrodes may sometimes be less than that of the positive
electrodes, since the negative electrode discharge reaction
products are sometimes dissolved in the battery electrolyte. The
porosity of the negative electrodes may be increased as the
discharge rate desired in the battery is increased. The negative
electrodes 30 may also comprise thin sheets or foils of
electrochemically negative material.
If the positive and negative electrodes 20 and 30 respectively have
the active material particles dispersed in a binder matrix as
mentioned above, they may be applied onto the coninuous strips by
such techniques as the rotogravure or reverse roll coating methods
used in the printing arts. Such methods are suitable for applying
liquids for varying viscosities onto carriers and may be used with
modern, high speed rotary production machinery. Where the
electrodes are deposited in the form of such liquids, the
electrodes should be dried before being further processed; the
drying can be achieved by passing the web through appropriate ovens
or drying chambers. Other methods of applying the positive
electrodes onto the web includes silk screening, stenciling, and
flexographic printing techniques; the particular application
technique selected will depend not only upon the composition of the
electrodes as they are deposited but on such additional factors as
the desired thickness of the electrodes, the speed at which the
continuous Zones move with respect to the applicators, and others.
It is preferred to use this invention with positive and negative
electrode compositions which, when placed onto Zones No. 1, No. 2
and No. 3, comprise active material particles dispersed in a binder
matrix.
It is necessary to place a separator and electrolyte between each
adjacent pair of electrodes in the collation. This requirement may
be met in different ways with different materials. One approach is
with the use of a continuous strip of separator material 40 such as
that illustrated in FIGS. 8 and 9. Such separators may be made from
a wide variety of materials including the synthetic fibers,
microporous polymer sheets, and cellulosic materials which are
conventional in battery construction as well as from woven or
non-woven fibrous materials such as polyester, nylon, polyproplene,
polyethylene, and glass. Liquid electrolyte solutions could be
impregnated into these separator strips or patches of viscous,
gelled electrolyte could be applied onto one or both sides of the
separator strip. The viscous, gelled electrolytes, which can be
made including a wide variety of gelling agents, would contain the
needed electrolyte and also adhere or bond to the adjacent
electrodes to produce good conductivity. As another alternative,
deposits of viscous, gelled electrolytes could by themselves serve
as both separators and as electrolyte if of proper thickness and/or
consistency, making a distinct separator such as the member 40
shown in FIGS. 8 and 9 unnecessary. All such alternatives are
included within this invention as ways of placing a separator and
electrolyte between each adjacent pair of electrodes in the
collation.
Several observations should be made in regard to the role of the
adhesive patches which provide the seals around the electrodes. As
mentioned earlier, preferably these patches may be impregnated into
the separator strip before the electrolyte is added to that strip.
The adhesive should be applied in liberal quantity so that all of
the pores in the separator are completely filled in the area to
which the adhesive is applied and so that there is sufficient
excessive adhesive to coat and adhere to the other members being
sealed by the patches. The adhesives should be electrically
nonconductive. The adhesives themselves may be selected from a wide
variety of materials including such adhesive cements as catalyzed
uncured epoxy resins, phenolic resin solutions, ethylene copolymer
hot melts, pressure sensitive elastomer mixtures, thermoplastic
resin solutions, and natural gums and resins and their solutions.
Faster and more thorough and complete impregnation of the adhesive
into the separator may be achieved with many hot melt cements by
making the impregnations with heat adhesives. The adhesives which
may be used may be ones which attain their adhesive quality for the
first time during assembly of the battery as a result of the
application of pressure, heat, ultrasonics, or other forms of
energy. Where gelled electrolytes are used as the only separators
between adjacent electrodes, sealant deposits 101 of the type shown
in FIGS. 2 and 3 may be used to achieve the sealing.
While it is preferred to employ the LeClanche electrochemical
system (comprising manganese dioxide positive active material, zinc
negative active material, and an electrolyte comprising ammonium
chloride and/or zinc chloride), the multicell battery 5 of this
invention may employ a wide variety of electrochemical systems
including both primary and secondary systems. Among the positive
electrode materials are such commonly used inorganic metal oxides
as manganese dioxide, lead dioxide, nickel oxyhydroxide, mercuric
oxide and silver oxide, inorganic metal halides such as silver
chloride and lead chloride and organic materials capable of being
reduced such as dinitrobenzene and azodicarbonamide compounds.
Among the negative electrode materials are such commonly used
metals as zinc, aluminum, magnesium, lead, cadmium, and iron. This
invention may employ the electrolytes commonly used in the
LeClanche system (ammonium chloride and/or zinc chloride), various
alkaline electrolytes such as the hydroxides of potassium, sodium
and/or lithium, acidic electrolytes such as sulfuric or phosphoric
acid, and nonaqueous electrolytes, the electrolytes of course being
chosen to be compatible with the positive and negative
electrodes.
Among the wide variety of electrochemical systems which may be used
in the multicell battery 5 are those in which the positive
electrodes comprise manganese dioxide, the negative electrodes
comprise metals such as zinc, aluminum, or magnesium, and the
electrolyte substantially comprises an acidic solution of inorganic
salts. Another commonly known system useful in the battery 5 is the
alkaline manganese system in which the positive electrodes comprise
manganese dioxide, the negative electrodes comprise zinc, and the
electrolyte substantially comprises a solution of potassium
hydroxide. Other aqueous electrolyte systems including those of
nickel-zinc, silver-zinc, mercury-zinc, mercury-cadmium, and
nickel-cadmium may also be used.
Systems employing organic positive electrodes and acidic
electrolytes may also be used, including rechargeable systems using
azodicarbonamide compound electrodes and LeClanche electrolyte.
With the all metal web described in Section 3, the surfaces of the
web must be selected from metals which are electrochemically
nonreactive with respect to the electrodes and electrolyte of the
battery. As further described in U.S. Pat. No. 3,706,616, the metal
carrier strip used as the web may comprise: (1) a unimetal which is
nonreactive to the positive and negative electrodes and to the
electrolyte within the battery; (2) a bimetal in which the metal
adjacent the positive electrode is nonreactive with respect to that
electrode and the metal adjacent the negative electrode is
nonreactive with respect to that electrode; (3) and, a trimetal
whose outer two layers are non-reactive as in (2). The particular
metals employed will depend upon the electrochemical system used in
the battery. Metals which are nonreactive in nearly all
electrochemical environments in common usage include titanium,
tantalum, and gold; these metals and others which are nonreactive
in some but not all electrochemical environments may be used. In
general, bimetals have the advantage of permitting a wider
selection of materials and of permitting a metals selection based
upon the idea that the metal on one side of the web may be
particularly nonreactive with respect to the positive electrodes
while the metal on the other side of the web may be particularly
nonreactive with respect to the negative electrodes. Use of
trimetals increases the range of possibilities by permitting the
interior metal to be selected on the basis of factors such as cost,
electrical conductivity, and ease of pocketing while the two
exterior metals may be selected primarily on the basis of their
electrochemical nonreactivity. Bimetal and trimetal constructions
may be obtained by cladding, plating, flame spraying, vacuum
deposition, or by any other suitable means.
* * * * *