U.S. patent application number 10/839149 was filed with the patent office on 2004-10-21 for manufacture of flexible thin layer electrochemical cell.
Invention is credited to Luski, Shalom, Nitzan, Zvi.
Application Number | 20040209160 10/839149 |
Document ID | / |
Family ID | 25379781 |
Filed Date | 2004-10-21 |
United States Patent
Application |
20040209160 |
Kind Code |
A1 |
Luski, Shalom ; et
al. |
October 21, 2004 |
Manufacture of flexible thin layer electrochemical cell
Abstract
A flexible thin layer electrochemical cell and a method of using
a lamination process for manufacture thereof, the cell having a
plurality of layers including a first electrode layer and a second
electrode layer with a separator interspersed therebetween and
wherein the separator serves as a lead element upon which the other
layers are laminated using an adhesive frame mounted on the lead
element.
Inventors: |
Luski, Shalom; (Rehovot,
IL) ; Nitzan, Zvi; (Zofit, IL) |
Correspondence
Address: |
Martin MOYNIHAN
c/o ANTHONY CASTORINA
SUITE 207
2001 JEFFERSON DAVIS HIGHWAY
ARLINGTON
VA
22202
US
|
Family ID: |
25379781 |
Appl. No.: |
10/839149 |
Filed: |
May 6, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10839149 |
May 6, 2004 |
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09882051 |
Jun 18, 2001 |
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6752842 |
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Current U.S.
Class: |
429/144 ;
429/130; 429/137 |
Current CPC
Class: |
H01M 50/46 20210101;
H01M 10/0486 20130101; Y02E 60/10 20130101; H01M 50/461 20210101;
Y02P 70/50 20151101; H01M 10/0436 20130101; H01M 6/12 20130101;
Y10T 29/49115 20150115; Y10T 29/49112 20150115 |
Class at
Publication: |
429/144 ;
429/137; 429/130 |
International
Class: |
H01M 002/16; H01M
002/18 |
Claims
What is claimed is:
1. A separator layer for use in the production of a flexible thin
layer electrochemical cell, said separator layer comprising an
impregnator applied thereto, which impregnator is susceptible to
impregnate said separator layer during lamination processing
applied to said layer to form said cell.
2. A separator layer according to claim 1, wherein said impregnator
comprises an adhesive material.
3. A separator layer according to claim 2, wherein said adhesive
material is selected from the group consisting of a hot melt
material, a hot melt pressure sensitive material and a UV curable
pressure sensitive material.
4. A separator layer according to claim 1, wherein said impregnator
comprises an impregnation agent operable to cause impregnation into
at least one of said layers of at least one material of said
impregnator.
5. A separator layer according to claim 1, wherein said impregnator
is operable to restrict electrical conductivity in a region of any
electrically conductive layer into which it is absorbed.
6. A separator layer according to claim 4, wherein said
impregnation agent is selected from the group consisting of
polyisobutylene, ethyl cellulose, a fluoro polymer, an acrylic
resin, a vinyl resin, and polyurethane.
7. A separator layer according to claim 1, having a first side and
a second side and having said impregnator applied on both of said
first side and said second side for lamination thereto of further
layers to form said cell.
8. A separator layer according to claim 7, having a positive
electrode layer laminated to said first side and a negative
electrode layer laminated to said second side, each electrode layer
further comprising electrolyte.
Description
[0001] This is a divisional of U.S. patent application Ser. No.
09/882,051, filed Jun. 18, 2001.
FIELD AND BACKGROUND OF THE INVENTION
[0002] The present invention relates to a flexible thin layer
electrochemical cell and more particularly, but not exclusively, to
materials for the manufacture of such a cell and a method of
manufacture thereof.
[0003] The present invention relates to the manufacture of
electrochemical cells which are used as power sources by converting
chemical energy to electrical energy, including batteries and other
types of electrochemical components which share structural features
therewith, including in particular capacitors and electrolytic
capacitors. More particularly, the present invention relates to a
primary or rechargeable electrochemical cell to be used as a
primary or rechargeable battery which accomplishes the conversion
of chemical energy to electrical energy using perhaps a wet (e.g.,
liquid state) electrolyte, yet maintains a flexible thin layer
configuration.
[0004] The most common type of battery is the cylindrical battery.
Cylindrical batteries include the bobbin type, in which one
electrode is a central axis and the other electrode is outwardly
located of the cylinder with electrolyte and a separator
therebetween.
[0005] A second type of cylindrical battery is the jellyroll
battery. In the jellyroll battery, an anode and a cathode are wound
tightly around a mandrel with a separator therebetween.
[0006] The ever-growing development of miniaturized and portable
electrically powered devices such as for example cellular phones,
voice recording and playing devices, watches, motion and still
cameras, liquid crystal displays, electronic calculators, IC cards,
temperature sensors, hearing aids, pressure sensitive buzzers,
etc., has generated a need for compact batteries for their
operation. Currently popular for such applications are button cells
which comprise flattened cylinders having an upper closure and a
lower closure. One electrode is attached to the upper closure and
the second electrode is attached to the lower closure of the
button. The two halves of the cylinder are then sealed together to
form the complete battery.
[0007] Nevertheless, the button battery has a relatively large
thickness due to its need for upper and lower surrounding metal
walls. The dimensions of the battery bound the extent of
miniaturization for many devices.
[0008] There thus arises a need for reliable thin layer
electrochemical cells to be used as batteries.
[0009] Batteries can be broadly classified into three categories in
which batteries of the first category include wet electrolytes
(i.e., liquid state batteries), and batteries of the second
category include solid state electrolyte. There is also a third,
gel type.
[0010] Solid state batteries have an inherent advantage, they do
not dry out and do not leak, they suffer major disadvantages when
compared with liquid state batteries since, due to limited
diffusion rates of ions through a solid, their operation is
temperature dependent to a much larger extent, and many operate
well only under elevated temperatures. Furthermore, the limited
diffusion rates result in batteries with low ratio of electrical
energy generated vs. their potential chemical energy.
[0011] Liquid state thin layer batteries typically include a
positive and negative active insoluble material layer put together
with a separator interposed therebetween, which separator is soaked
with a liquid electrolyte solution, thus functioning as an
electrolytic liquid layer. Such batteries, examples of which are
disclosed in U.S. Pat. No. 4,623,598 to Waki et al., and in
Japanese Pat. No. JP 61-55866 to Fuminobu et al., are sealed within
a sheathing film to prevent liquid evaporation, and therefore form
closed electrochemical cells. Being closed cells, these batteries
tend to swell upon storage due to evolution of gases which is a
fatal problem in thin layer batteries having no mechanical support,
the pressure imposed by the accumulated gases leads to layer
separation, thus rendering the battery inoperative.
[0012] Means to overcome this problem include (i) the use of a
polymer increased viscosity agent, such as hydroxyethylcellulose,
applied to adhere (i.e., glue) the battery layers together, thus
overcoming the problem of lack of solid support; and, (ii) the
addition of mercury, which is particularly useful in the prevention
of hydrogen formation.
[0013] It is noted, however, that the polymer is limited in its
effectiveness and the mercury is an environmental hazard. Thus the
problems are not successfully overcome.
[0014] A way to solve the swelling problem was disclosed in U.S.
Pat. No. 3,901,732 to Kis et al. in which a gas-permeable
electrolyte-impermeable polymeric material which allows venting of
undesirable gases formed within the battery while preventing any
electrolyte loss from the battery is used as a sheathing film to
enclose the battery cell.
[0015] However, a more direct and efficient way to avoid undesired
gas accumulation in liquid state thin layer batteries would be to
provide these batteries as open cells for facilitated release of
gases, while at the same time to provide means to avoid liquid
evaporation and drying out of the battery.
[0016] U.S. Pat. No. 5,652,043 thus provides a flexible thin layer
open liquid state electrochemical cell, which can be used as a
primary or rechargeable power supply for various miniaturized and
portable electrically powered devices of compact design. The cell
includes a wet electrolyte, yet maintains a flexible, thin and open
configuration, thus devoid of accumulation of gases upon storage.
The cell comprising a first layer being an insoluble negative pole,
a second layer being an insoluble positive pole and a third layer
being aqueous electrolyte, the third layer being disposed between
the first and second layers and including a deliquescent material
for keeping the open cell wet at all times; an electroactive
soluble material for obtaining required ionic conductivity; and, a
water-soluble polymer for obtaining a required viscosity for
adhering the layers. The electrochemical cell therein described is
preferably produced using a suitable printing technology.
[0017] International Patent Application WO 98/56458 discloses a
flexible thin layer open cell and discusses a method of manufacture
thereof.
[0018] Flexible thin layer lithium cells were reported in
Scientific American October 1997, as follows:
[0019] The lithium power source is a recent development in mobile
power sources. The battery is flat and flexible, like a stick of
chewing gum (one of its manufacturers refers to its product as a
film battery because its batteries are also reminiscent of film
frames). These batteries, which could soon be as thin as 0.2
millimeter, can be manufactured in long, continuous strips, which
should reduce production costs. Both NiCd and NiMH cells can also
be produced using the chewing gum format.
[0020] Generally, a battery of the above-described kind is
manufactured by printing different layers one on top of the other.
Manufacture begins with a first electrode, upon which a separator
containing electrolyte is printed, and then a second electrode may
be printed over that. The layers are packaged in plastic; the
plastic layers being attached from around the edges by the
insertion of a sealing compound.
SUMMARY OF THE INVENTION
[0021] According to a first aspect of the present invention there
is thus provided a method of using a lamination process to make a
flexible thin layer electrochemical cell having a plurality of
layers including a first and a second electrode layer with a
separator in between and wherein the separator serves as a lead
element upon which the other layers are laminated.
[0022] According to a second aspect of the present invention there
is provided a method of manufacturing a thin layer electrochemical
cell comprising the steps of:
[0023] providing a separator layer;
[0024] providing a positive electrode layer,
[0025] providing a negative electrode layer, and
[0026] laminating together the positive and negative electrode
layers onto the separator layer.
[0027] A preferred embodiment comprises the step of impregnating a
non-conductive material to form a non-conductive region within at
least one of the layers.
[0028] Preferably, the step of laminating further comprises
impregnating a non-conductive material to form a non-conductive
sealed region within at least one of the layers.
[0029] Preferably, the non-conduction region is formed as a border
defining an outer boundary of the cell.
[0030] Preferably, the non-conduction region extends through at
least two of the layers.
[0031] Preferably, the non-conduction region extends through all
three of the layers.
[0032] Preferably, the thin layer electrochemical cell is an open
thin layer electrochemical cell.
[0033] A preferred embodiment comprises the step of applying a
partial layer of non-conduction material to the separator
layer.
[0034] Preferably, the non-conductive material is an adhesive
material.
[0035] Preferably, the adhesive material is any one of a group
comprising urethane acrylate, epoxy acrylate, other cross-linked
acrylates, and cured acrylates.
[0036] Preferably, the non-conduction material is selected from the
group consisting of a hot melt material, a hot melt pressure
sensitive material and a UV curable pressure sensitive
material.
[0037] A preferred embodiment comprises comprising the step of
adding an impregnation agent to the partial layer.
[0038] Preferably, the impregnation agent is selected from the
group consisting of polyisobutylene, ethyl cellulose, a fluoro
polymer, an acrylic resin, a vinyl resin, and polyurethane.
[0039] According to a third aspect of the present invention there
is provided a separator layer for use in the production of a
flexible thin layer electrochemical cell, the separator layer
comprising an impregnator applied thereto, which impregnator is
susceptible to impregnate the separator layer during lamination
processing applied to the layer to form the cell.
[0040] Preferably, the impregnator comprises an adhesive
material.
[0041] Preferably, the adhesive material is selected from the group
consisting of a hot melt material, a hot melt pressure sensitive
material and a UV curable pressure sensitive material.
[0042] Preferably, the impregnator comprises an impregnation agent
operable to cause impregnation into at least one of the layers of
at least one material of the impregnator.
[0043] Preferably, the impregnator is operable to restrict
electrical conductivity in a region of any electrically conductive
layer into which it is absorbed.
[0044] Preferably, the impregnation agent is selected from the
group consisting of polyisobutylene, ethyl cellulose, a fluoro
polymer, an acrylic resin, a vinyl resin, and polyurethane.
[0045] A preferred embodiment has a first side and a second side
and the impregnator is applied on both of the first side and the
second side for lamination thereto of further layers to form the
cell.
[0046] A preferred embodiment has a positive electrode layer
laminated to the first side and a negative electrode layer
laminated to the second side, each electrode layer further
comprising electrolyte.
[0047] According to a fourth aspect of the present invention there
is provided a flexible thin layer open electrochemical cell
comprising a plurality of layers laminated to one another.
[0048] In a preferred embodiment, layers comprise a conduction
inhibitor absorbed within the layers to form non-conduction
regions.
[0049] In a preferred embodiment, the conduction inhibitor
comprises an adhesive material.
[0050] In a preferred embodiment, the adhesive material being is
selected from the group consisting of a hot melt material, a hot
melt pressure sensitive material and a UV curable pressure
sensitive material.
[0051] In a preferred embodiment, the conduction inhibitor further
comprises an impregnation agent.
[0052] In a preferred embodiment, the impregnation agent including
is selected from the group consisting of polyisobutylene, ethyl
cellulose, a fluoro polymer, an acrylic resin, a vinyl resin, and
polyurethane.
[0053] Preferably, the non-conducting regions are arranged to
define borders of the cell.
[0054] Preferably, the adhesive is suitable for laminating the
layers together in a lamination process.
[0055] Preferably, the base layer comprises an impregnator located
thereon, which impregnator is operable to impregnate the separator
layer during lamination processing applied to the layer to form the
cell.
[0056] Preferably, the impregnator comprises an adhesive suitable
for adhering the layers during lamination processing.
[0057] Preferably, the adhesive is selected from the group
consisting of a hot melt material, a hot melt pressure sensitive
material and a UV curable pressure sensitive material.
[0058] Preferably, the impregnator further comprises an
impregnation agent operable to cause impregnation into the layers
of at least one material of the impregnator.
[0059] Preferably, the impregnation agent is selected from the
group consisting of po, ethyl cellulose, a fluoro polymer, an
acrylic resin, a vinyl resin, and polyurethane.
[0060] A preferred embodiment comprises a first side and a second
side and the impregnator is superimposed on both of the first side
and the second side for lamination thereto of further layers to
form the cell.
[0061] A preferred embodiment comprises a positive electrode layer
laminated to the first side and a negative electrode layer
laminated to the second side, each electrode layer further
comprising electrolyte.
[0062] Preferably, the impregnation region extends into the
electrode layers.
[0063] Preferably, the impregnator is operable to form
non-conducting impregnation regions in the electrode layers.
[0064] Preferably, the non-conducting regions define a border
closing a region of the layer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0065] For a better understanding of the invention and to show how
the same may be carried into effect, reference will now be made,
purely by way of example, to the accompanying drawings.
[0066] With specific reference now to the drawings in detail, it is
stressed that the particulars shown are by way of example and for
purposes of illustrative discussion of the preferred embodiments of
the present invention only, and are presented in the cause of
providing what is believed to be the most useful and readily
understood description of the principles and conceptual aspects of
the invention. In this regard, no attempt is made to show
structural details of the invention in more detail than is
necessary for a fundamental understanding of the invention, the
description taken with the drawings making apparent to those
skilled in the art how the several forms of the invention may be
embodied in practice. In the accompanying drawings:
[0067] FIG. 1 is a cutaway drawing of a length of a first kind of a
prior art flexible thin layer electrochemical cells arranged in a
roll.
[0068] FIG. 2 is a cross-section of a second prior art flexible
thin layer electrochemical cell.
[0069] FIG. 3 is a cross-section of the prior art cell of FIG. 2,
showing sealing from around the side.
[0070] FIG. 4 is a view from above of a flexible thin layer
electrochemical cell operative in accordance with a first
embodiment of the present invention,
[0071] FIG. 5 is a cross-sectional view along line A-A of the
embodiment of FIG. 4 during a first manufacturing step,
[0072] FIG. 6 is a cross-sectional view along line A-A of the
embodiment of FIG. 4 during a second manufacturing step, and
[0073] FIG. 7 is a simplified view of a lamination step in the
manufacture of a flexible thin-layer electrochemical cell operative
in accordance with embodiments of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0074] Before explaining at least one embodiment of the invention
in detail, it is to be understood that the invention is not limited
in its application to the details of construction and the
arrangement of the components set forth in the following
description or illustrated in the drawings. The invention is
applicable to other embodiments or of being practiced or carried
out in various ways. Also, it is to be understood that the
phraseology and terminology employed herein is for the purpose of
description and should not be regarded as limiting.
[0075] Reference is now made to FIG. 1, which is a cutaway drawing
of a length 10 of a first kind of prior art flexible thin layer
electrochemical cell as one of a series of cells in a roll 12. The
length 10 comprises a plurality of individual cells 14 each having
a positive terminal 16 and a negative terminal 18. Each cell has a
positive electrode layer 20 and a negative electrode layer 22 and
each electrode layer is associated with a current collector,
respectively positive current collector 24 and negative current
collector 26. Located between the positive and negative electrodes
is a solid polymer electrolyte 28. The electrolyte is typically
based on PEO, PAN, and PVDF-like materials.
[0076] Running around the outside of the cell 14 is a sealing
compound 27 which seals the layers in contact for use. The
arrangement is mounted on a carrier 29.
[0077] The sealing compound is generally added from the side after
completing assembly of the layers.
[0078] Reference is now made to FIG. 2, which is a cross-section of
a second prior art flexible thin layer electrochemical cell. In the
embodiment of FIG. 2 a cell 30 comprises a first outer plastic
layer 32, a negative current collector 34, a negative electrode 36
with electrolyte, a separator 38, a positive electrode 40 with
electrolyte, a positive current collector 42 and a plastic layer
44.
[0079] Reference is now made to FIG. 3, which is an extended
cross-section of FIG. 2 and shows how the device of FIG. 2 may be
sealed. Parts that are identical to those shown above are given the
same reference numerals and are not referred to again except as
necessary for an understanding of the present embodiment. The
internal layers are generally printed one upon the other and then
the layers of plastic 32 and 44 are placed around the outside. The
plastic layers extend outwardly of the other layers and a sealant
50 is applied around the edges between the plastic layers 32 and 44
to seal the cell 30. Application of the sealant may be carried out
from around the edges. The sealant provides a non-conducting region
and since the cell is sealed using a non-conducting region, the
possibilities of short-circuiting are minimized.
[0080] Reference is now made to FIG. 4, which shows a length of a
separator 38, as for the device shown in FIGS. 2 and 3, but adapted
to be operative in accordance with a first embodiment of the
present invention. In the present embodiments, a liquid electrolyte
is used and the solid separator is preferably soaked with the
liquid electrolyte.
[0081] As shown in FIG. 4, a square frame 60 is applied to the
separator 38. The frame 60 preferably comprises adhesive material
which is adsorbed into the separator and which extends outwards
above and below of the separator. The adhesive material is a
material designed for use in lamination processes, and the frame 60
is preferably applied to both sides of the separator 38. Suitable
adhesive materials include hot melt materials of various types, hot
melt pressure sensitive materials and UV curable pressure sensitive
materials.
[0082] There are two main methods of impregnation, one of them
being impregnation with a solution containing a dissolved
impregnator and a solvent, followed by evaporating the solvent, and
the second being impregnation with a liquid phase and then
developing or curing by suitable radiation. This latter method uses
low viscosity materials and requires curing by UV or other types of
radiation, such as electron beam radiation. In order to absorb the
material into the separator 38, and, as will be explained below,
also into the other layers, a suitable impregnation agent is
preferably used. Possible impregnation agents include
polyisobutylene, ethyl cellulose, various fluoro polymers, acrylic
resins, vinyl resins, and polyurethane.
[0083] Preferably, absorption of the adhesive into the separation
layer forms a non-conductive sealed frame around the separator, and
prevents leakage of electrolyte from the separator. Solvent-based
systems generally use low viscosity materials and curing may be
carried out using UV radiation or E.B.
[0084] Reference is now made to FIG. 5, which is a simplified
diagram of a section taken along line A-A in FIG. 4, showing
impregnation within the separator layer 38. Parts that are
identical to those shown above are given the same reference
numerals and are not referred to again except as necessary for an
understanding of the present embodiment. The combination of the
adhesive and the impregnation agent causes impregnation of the
separator 38 to bring about a sealant or impregnation region 62
within the separator 38. The impregnation region around the
separator is preferably non-conductive, as mentioned above and
prevents leakage of electrolyte from the separator. As will be
explained below, the effect of the frame and the lamination process
produces a similar result on each of the other layers.
[0085] Reference is now made to FIG. 6, which is a simplified
diagram of a section taken along line A-A in FIG. 4 following
absorption. Parts that are identical to those shown above are given
the same reference numerals and are not referred to again except as
necessary for an understanding of the present embodiment. FIG. 6
shows the addition of the frame 60 over the impregnation region 62
on either side thereof, in readiness for a stage of lamination
during which further layers may be applied on either side of the
separator 38.
[0086] Reference is now made to FIG. 7, which is a simplified
diagram showing a lamination step in the manufacturing process of a
cell according to the present invention. Parts that are identical
to those shown above are given the same reference numerals and are
not referred to again except as necessary for an understanding of
the present embodiment. In the step of FIG. 7, a separator layer 38
having a frame 60 superimposed thereupon, is passed through a
lamination unit 70, along with upper and lower electrode layers 72
and 74. The upper and lower layers each preferably comprise an
electrode 36, 40, and preferably have a coating of electrolyte
76.
[0087] The lamination unit applies heat, pressure, UV, EB etc. or a
combination thereof as appropriate for the materials being used and
presses the layers together to laminate them. Preferably, the
impregnation agent being used ensures that there is absorption of
the adhesive of the frame 60 through tlayers being laminated
together such that each one of them has an impregnation region as
shown in FIG. 5.
[0088] The adhesive frame 60 defines the borders between individual
cells. As the positioning of the border is fully defined by just
one of the layers, namely the separator 38, accurate alignment
between the layers is preferably not required.
[0089] The lamination process preferably forms a continuous tape of
the kind shown in FIG. 1. The tape can be cut along lines formed by
the adhesive frame to form flexible battery cells. The edges of the
cell are firmly fixed in a non-conducting and non-leaking medium
which preferably extends right through the layers along the cutting
region.
[0090] According to the above embodiments there is thus provided a
flexible thin layer electrochemical cell and a method of using a
lamination process for manufacture thereof, the cell having a
plurality of layers including a first electrode layer and a second
electrode layer with a separator interspersed therebetween and
wherein the separator serves as a lead element upon which the other
layers are laminated using an adhesive frame mounted on the lead
element.
[0091] It is appreciated that certain features of the invention,
which are, for clarity, described in the context of separate
embodiments, may also be provided in combination in a single
embodiment. Conversely, various features of the invention which
are, for brevity, described in the context of a single embodiment,
may also be provided separately or in any suitable
subcombination.
[0092] It will be appreciated by persons skilled in the art that
the present invention is not limited to what has been particularly
shown and described hereinabove. Rather the scope of the present
invention is defined by the appended claims and includes both
combinations and subcombinations of the various features described
hereinabove as well as variations and modifications thereof which
would occur to persons skilled in the art upon reading the
foregoing description.
* * * * *