U.S. patent application number 10/097990 was filed with the patent office on 2002-07-25 for in-line printing of electrolyte patterns of electrochemical cells.
Invention is credited to Friesch, Andrew J., Good, David M., Mitchell, Chauncey T. JR., Shadle, Mark A., Verschuur, Gerrit L..
Application Number | 20020095780 10/097990 |
Document ID | / |
Family ID | 26807532 |
Filed Date | 2002-07-25 |
United States Patent
Application |
20020095780 |
Kind Code |
A1 |
Shadle, Mark A. ; et
al. |
July 25, 2002 |
In-line printing of electrolyte patterns of electrochemical
cells
Abstract
An electrolyte is formulated as a printing ink and laid down by
an in-line press for manufacturing printed electrochemical cells. A
curing station transforms the electrolyte to perform additional
functions such as separating electrodes, preventing leakage,
bonding cell layers, and resisting evaporation.
Inventors: |
Shadle, Mark A.; (Peachtree
City, GA) ; Good, David M.; (Ketchikan, AK) ;
Friesch, Andrew J.; (Cedarburg, WI) ; Mitchell,
Chauncey T. JR.; (Lakeland, TN) ; Verschuur, Gerrit
L.; (Lakeland, TN) |
Correspondence
Address: |
THOMAS B. RYAN
EUGENE STEPHENS & ASSOCIATES
56 WINDSOR ST
ROCHESTER
NY
14605
US
|
Family ID: |
26807532 |
Appl. No.: |
10/097990 |
Filed: |
March 14, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10097990 |
Mar 14, 2002 |
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09448371 |
Nov 23, 1999 |
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6395043 |
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60109943 |
Nov 25, 1998 |
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Current U.S.
Class: |
29/623.5 ;
427/58; 429/124 |
Current CPC
Class: |
Y10T 29/49112 20150115;
H01M 6/188 20130101; Y02P 70/50 20151101; Y10T 29/49115 20150115;
H01M 6/40 20130101; Y10T 29/49114 20150115 |
Class at
Publication: |
29/623.5 ;
429/124; 427/58 |
International
Class: |
H01M 010/04; H01M
006/40 |
Claims
We claim:
1. A method of in-line printing electrolyte patterns of
electrochemical cells comprising the steps of: formulating an
electrolyte composition having low adhesive properties; printing
the electrolyte composition having low adhesive properties in a
repeating pattern along an advancing web; and chemically
transforming the electrolyte composition of the printed electrolyte
patterns along the advancing web from an electrolyte composition
having low adhesive properties to an electrolyte composition having
high adhesive properties.
2. The method of claim 1 in which the electrolyte composition is
formulated for transfer printing and said step of printing includes
transfer printing the electrolyte composition.
3. The method of claim 1 in which said step of chemically
transforming includes polymerizing the electrolyte composition.
4. The method of claim 3 in which the chemically transformed
electrolyte composition is a pressure-sensitive adhesive.
5. The method of claim 1 in which said step of chemically
transforming includes transforming the electrolyte composition from
an electrolyte composition that exhibits low stickiness to an
electrolyte composition that exhibits high stickiness.
6. The method of claim 1 including the further steps of: (a)
printing more of the electrolyte composition having low adhesive
properties over the chemically transformed electrolyte patterns;
and (b) chemically transforming the overprinting electrolyte
composition from an electrolyte composition having low adhesive
properties to an electrolyte composition having high adhesive
properties for increasing the total thickness of the electrolyte
composition having high adhesive properties on the web.
7. The method of claim 1 in which said step of formulating includes
formulating the electrolyte composition so that the printed
electrolyte composition having low adhesive properties flows under
a force of gravity.
8. The method of claim 7 further comprising a step of forming a
succession of reservoirs having a boundary shape along the
advancing web.
9. The method of claim 8 in which said step of printing includes
injecting metered volumes of the electrolyte composition into the
succession of reservoirs.
10. The method of claim 9 in which said step of forming includes
applying a masking layer to the advancing web for forming the
succession of reservoirs.
11. The method of claim 10 including the further step of patterning
the masking layer with the boundary shape of the reservoirs.
12. A method of in-line printing electrolyte patterns of
electrochemical cells comprising the steps of: forming a succession
of reservoirs having a boundary shape along an advancing web;
injecting metered volumes of an electrolyte composition into the
succession of reservoirs; formulating the electrolyte composition
so that the injected volumes of the electrolyte composition conform
to the shape of the reservoirs; and transforming the injected
volumes of the electrolyte composition into a more permanent shape
matching the shape of the reservoirs.
13. The method of claim 12 in which said step of formulating
includes formulating the electrolyte composition so that the
injected volumes of the electrolyte composition flow under a force
of gravity.
14. The method of claim 13 in which said electrolyte composition is
formulated with a zero yield value.
15. The method of claim 12 in which said step of forming includes
applying a masking layer to the advancing web for forming the
succession of reservoirs.
16. The method of claim 15 including the further step of patterning
the masking layer with the boundary shape of the reservoirs.
17. The method of claim 12 in which said step of forming includes
successively impressing the boundary shape into the advancing
web.
18. The method of claim 12 in which said step of injecting includes
injecting the volume of electrolyte composition onto a printed
electrode pattern.
19. The method of claim 12 in which said step of transforming
includes chemically transforming the electrolyte composition from a
state of lower viscosity to a state of higher viscosity.
20. The method of claim 12 in which said step of transforming
includes chemically transforming the electrolyte composition from a
state of lower adhesiveness to a state of higher adhesiveness.
21. The method of claim 12 in which said step of formulating
includes formulating the electrolyte composition to contain an
electrolyte and a monomer.
22. The method of claim 21 in which said step of transforming
includes converting the monomer into a polymer that forms a matrix
within which the electrolyte is embedded.
23. The method of claim 12 in which said step of forming includes
forming a dual succession of reservoirs having boundary shapes
along the advancing web.
24. The method of claim 23 including a further step of pressing the
dual reservoirs together to join the injected volumes of
electrolyte.
25. A method of printing electrochemical cells comprising the steps
of: separately formulating at least one electrode composition and
an electrolyte composition in transfer printable inks; transfer
printing the at least one electrode composition and the electrolyte
composition from successive printing stations of the in-line press
in repeating patterns on at least one of two web layers; chemically
transforming the electrolyte composition into an electrolytic
pressure-sensitive adhesive; and using the electrolytic
pressure-sensitive adhesive to bond the two web layers and to
complete at least a portion of an ionically conductive pathway
between two electrodes of a progression of transfer-printed
electrochemical cells.
26. The method of claim 25 in which said step of transfer printing
includes transfer printing the at least one electrode composition
in a repeating pattern on a first of said two web layers and
transfer printing the electrolyte composition in a repeating
pattern on the at least one electrode composition.
27. The method of claim 26 including the further steps of transfer
printing more of the electrolyte composition over the electrolytic
pressure-sensitive adhesive and chemically transforming the
electrolyte composition into more of the electrolytic
pressure-sensitive adhesive for increasing thickness of the
electrolytic pressure-sensitive adhesive.
28. The method of claim 25 in which said step of using the
electrolytic pressure-sensitive adhesive includes bonding a
succession of printed electrodes supported on one of the two web
layers to a succession of electrodes supported on the other of the
two web layers.
29. The method of claim 28 in which said step of using the
electrolytic pressure-sensitive adhesive includes electronically
isolating the electrodes supported on the one web layer with the
electrodes supported on the other of the two web layers.
30. The method of claim 25 in which said step of chemically
transforming includes polymerizing the electrolyte composition.
31. The method of claim 25 in which said step of transfer printing
includes flexographic printing the at least one electrode
composition and the electrolyte composition.
32. A method of printing electrochemical cells comprising the steps
of: advancing at least one web supporting anode and cathode layers
in a succession of patterns; laying down a first layer of
electrolyte in a succession of patterns on said anode layer; laying
down a second layer of electrolyte in a succession of patterns on
said cathode layer; curing the first and second layers of
electrolyte while in contact with the anode and cathode layers; and
laminating the first layer of electrolyte together with the second
layer of electrolyte for completing ionically conductive pathways
between the anode and cathode layers.
33. The method of claim 32 in which the first and second layers of
electrolyte laid down in patterns include a monomer mixed with the
electrolyte.
34. The method of claim 33 in which said step of curing includes
transforming the monomer into a polymer that forms a matrix within
which the electrolyte is embedded.
35. The method of claim 32 in which the first and second layers of
electrolyte laid down in patterns have low adhesive properties.
36. The method of claim 35 in which said step of curing increases
the adhesive properties of the first and second layers of
electrolyte.
37. The method of claim 32 in which said step of curing includes
polymerizing the electrolyte layers.
38. The method of claim 32 in which the cured electrolyte layers
are transformed into pressure-sensitive adhesives.
39. The method of claim 32 in which said step of curing includes a
first sub-step of radiation curing the first electrolyte layer and
a second sub-step of radiation curing the second electrolyte
layer.
40. The method of claim 39 in which said step of laminating joins
the separately cured electrolyte layers together.
41. The method of claim 32 further comprising a step of forming a
succession of reservoirs having a boundary shape along the
advancing web.
42. The method of claim 41 in which at least one of said steps of
laying down includes injecting metered volumes of the electrolyte
composition into the succession of reservoirs.
43. The method of claim 42 in which said step of forming includes
applying a masking layer to the advancing web for forming the
succession of reservoirs.
44. The method of claim 43 including the further step of patterning
the masking layer with the boundary shape of the reservoirs.
45. The method of claim 32 in which the steps of laying down
include transfer printing at least one of the first and second
layers of electrolyte.
46. A succession of electrochemical cells made according to the
method of claim 32.
Description
RELATED APPLICATIONS
[0001] This application is a Division of copending allowed parent
Application Ser. No. 09/1448,371, filed Nov. 23, 1999, by Mark A.
Shadle, David M. Good, Andrew J. Friesch, Chauncey T. Mitchell,
Jr., and Gerrit L. Verschuur, entitled PRINTING ELECTROCHEMICAL
CELLS WITH IN-LINE CURED ELECTROLYTE, which parent application
claims the benefit of Provisional Application No. 60/109,943, filed
Nov. 25, 1998. All prior applications are hereby incorporated by
reference.
TECHNICAL FIELD
[0002] Electrolytes considered for this invention are applied in
layers and transformed to provide additional functions such as
separating electrodes, holding position, preserving ionic
conductivity, or bonding other layers of electrochemical cells. The
electrolyte and electrode layers can be laid down by an in-line
press in repeating patterns to manufacture a succession of thin,
flexible, low cost, and low power electrochemical cells.
BACKGROUND
[0003] Printed electrochemical cells and batteries (multiple cells)
are still relatively rare despite a number of published inventions
relating to their manufacture, which involves printing at least
some of their active layers and laminating others in sheet or web
form. Some of the problems still affecting the success of printed
electrochemical cells involve difficulties with printing effective
electrolyte layers interconnecting layers of electrodes.
[0004] One early attempt at printing electrochemical cells is
disclosed in U.S. Pat. No. 2,688,649 to Bjorksten. Electrode/
electrolyte combinations are formulated as inks and laid down in
repeating patterns by transfer printing, which includes letterpress
or offset printing. Magnetic powders together with an electrolyte
solution are suspended in a printing vehicle such as a drying oil
or a resinous material. After printing, the ink is passed through
an oriented magnetic field and dried. Another ink containing a
different magnetic powder is printed over the first layer,
magnetically oriented, and dried to complete a printed "dry cell".
Although printed, the electrolyte is printed together with the
electrode powders, which limits cell configurations (e.g.,
side-by-side electrodes) and the ability of the electrolyte to
function as a separator between the electrodes.
[0005] U.S. Pat. No. 3,230,115 to Tamminen discloses printed
electrochemical cells in which a metallic zinc electrode and a
carbonaceous electrode are laid down side-by-side in repeating
patterns and covered by a porous material wetted with electrolyte
in the form of a viscous adhesive gel. The electrolyte is a calcium
chloride solution gelled by wheat flour. The suggestions for
printing include applying the electrode layers by coating and
impregnating a porous paper with the electrolyte before applying
the paper to the electrodes. Two more recent examples of printed
cells with porous separators impregnated with electrolyte are
disclosed in U.S. Pat. Nos. 5,055,968 to Nishi et al. and 5,652,043
to Nitzan. Although absorbed by a separator, such liquid
electrolytes are difficult to confine and are subject to
evaporation.
[0006] A solid electrolyte layer separates electrode layers of a
printed cell disclosed in U.S. Pat. No. 5,350,645 to Lake et al.
Accordingly, the electrolyte must be laminated rather than printed
and is limited to unusual and expensive materials that are solid
but contain moveable ions. For example, solid lithium iodide is
suggested as an electrolyte between a lead iodide cathode and a
lithium anode.
[0007] Another example of a printed lithium cell is disclosed in
U.S. Pat. No. 5,035,965 to Sangyoji et al. The proposed electrolyte
is an ion-conductive polymer obtained by mixing polyethylene oxide
with lithium salt. Screen printing is used to apply the polymer
electrolyte to a metal foil electrode, and a so-called
UV-calcinating oven dries the electrolyte into a solid form.
Ordinary electrolytes are generally not ionically conductive in a
solid form; and polymer based electrolytes, such as those disclosed
in the Sangyoji et al. patent, are generally not useful for
formulating printing inks of more rapid transfer printing
operations, such as flexographic printing.
SUMMARY OF INVENTION
[0008] We propose the manufacture of electrochemical cells with an
electrolyte that can be laid down as a liquid printable ink and
subsequently transformed to perform additional functions such as
separating electrodes, holding position, preserving ionic
conductivity, or bonding cell layers together. For example,
electrolyte formulations can be made that are particularly suitable
for transfer or injection printing but can also be cured into an
adhesive state.
[0009] One method of forming a succession of such electrochemical
cells along an in-line press includes formulating an electrolyte
composition containing both an electrolyte and a monomer. The
electrolyte composition is printed in a succession of patterns on
an advancing web and is subsequently transformed by converting the
monomer into a polymer that forms a matrix within which the
electrolyte is embedded. The successions of electrolyte and
electrode patterns are arranged to form a succession of
electrochemical cells along the web.
[0010] The electrolyte composition containing the monomer
preferably has low viscosity and low adhesive characteristics
consistent with conventional liquid printing ink and is adaptable
to ink printing techniques such as transfer or injection printing.
The transformation step increases both the viscosity and the
adhesive characteristics of the printed electrolyte composition for
performing a bonding function between other layers supported on the
web. The resulting electrolytic adhesive holds position within the
cell and is less susceptible to drying out.
[0011] Another method emphasizing the printing of electrochemical
cells with electrolyte patterns having high-adhesive properties
starts with an electrolyte composition that is formulated for
having low adhesive properties. The electrolyte composition having
low adhesive properties is printed in a repeating pattern along an
advancing web. The repeating patterns are chemically transformed to
exhibit high adhesive properties, which is useful for such purposes
as bonding other cell layers together or separating overlapping
electrode layers. The chemical transformation can involve
polymerizing or crosslinking the electrolyte composition resulting,
for example, in a patterned electrolyte that is also a
pressure-sensitive adhesive.
[0012] Transfer printing can be used for printing electrochemical
cells along an in-line press by separately formulating at least one
electrode composition and an electrolyte composition in transfer
inks. The electrode composition and the electrolyte composition are
printed by successive printing stations of the in-line press in
repeating patterns on at least one of two web layers. A curing
station chemically transforms the electrolyte composition into an
electrolytic pressure-sensitive adhesive that bonds the two web
layers together and that completes at least a portion of an
ionically conductive pathway between two electrodes of a
progression of transfer-printed electrochemical cells.
[0013] Injection printing can also be used for printing similar
electrochemical cells along an in-line press by formulating the
electrolyte composition to permit pooling of the electrolyte in
preformed reservoirs. A succession of the reservoirs is formed
along an advancing web, and a periodic injection of a metered
volume of the electrolyte fills the reservoirs. The electrolyte,
which is injected in a flowable form, assumes the shape of the
reservoirs by force of gravity. A subsequent curing step chemically
transforms the electrolyte into a more permanent form, such as a
pressure-sensitive adhesive.
[0014] The in-line manufacture of electrochemical cells in
accordance with our invention can also include the laying down of
more than one electrolyte layer. At least one web supporting anode
and cathode layers in successions of patterns is advanced through
an in-line press. A first layer of electrolyte is laid down in a
succession of patterns on the anode layer, and a second layer of
electrolyte is laid down in a succession of patterns on the cathode
layer. The two electrolyte layers are cured while separately in
contact with the anode and cathode layers. A laminating operation
joins the two cured electrolyte layers together to complete
ionically conductive pathways between the anode and cathode
layers.
[0015] Curing individual electrolyte layers in contact with one or
both electrode layers improves ionic conductivity between the
electrolyte and electrode layers by eliminating surface formations
that can block ion transfers. Individual layers of electrolyte can
be later joined together without the same adverse consequences
because of their natural affinity for each other. In addition, the
enhanced flow characteristics of the applied electrolyte allow the
electrolyte to conform to surface irregularities, particularly
those of printed electrodes having rough or granular surfaces. The
more intimate molecular contact between the electrolyte and
electrode layers improves both bonding strength and ionic
conductivity through the interface.
[0016] One version of an electrochemical cell arranged in
accordance with our invention includes two electrode layers and an
electrolyte composition laid out on at least one substrate. The
electrolyte composition is chemically transformed by polymerization
into a matrix structure containing an embedded electrolyte with
disassociatable ions moveable between the electrode layers.
[0017] The electrolyte composition is preferably polymerized in
contact with the one electrode layer forming an interface that
promotes movement of ions between the one electrode layer and the
electrolyte composition. The electrolyte composition can also be
laid down in two layers that are separately cured in contact with
the two electrode layers and that are later joined to complete an
ionically conductive pathway between the electrode layers.
DRAWINGS
[0018] FIG. 1 is a diagram of an in-line press having transfer
printing stations for forming a succession of electrochemical
cells.
[0019] FIG. 2 is a plan view of the cells made on the press of FIG.
1 and arranged to provide display or timing functions.
[0020] FIG. 3 is a diagram of another in-line press having transfer
printing stations for forming a succession of electrochemical
cells.
[0021] FIG. 4 is a cross-sectional view of the cells made on the
press of FIG. 3 and arranged for providing a source of electrical
power to an external circuit.
[0022] FIG. 5 is a diagram of an in-line press having a combination
of transfer and injection printing stations for forming a
succession of electrochemical cells.
[0023] FIG. 6 is a plan view of a web section having advanced just
part way through the press of FIG. 5 showing the electrochemical
cells in a partial state of completion.
[0024] FIG. 7 is a cross-sectional view of the completed cells made
on the press of FIG. 5.
DETAILED DESCRIPTION
[0025] Much of this invention is focused on the printing and
transformation of electrolyte, particularly for the purpose of
advancing the manufacture of printed electrochemical cells. The
arrangement of such cells can vary widely, such as electrodes laid
out side-by-side or in stacked configurations. The electrodes can
also be shaped to provide portions of an electronically conductive
pathway independent of an ionically conductive pathway supported by
the electrolyte. Other layers including conductors, collectors, and
dielectric separators can also be used to support cell
functions.
[0026] We generally prefer to print all of the active cell layers
along one or more advancing webs but recognize that one or more of
the electrodes or other active layers could be formed in advance
along the webs. Some of the many cell configurations applicable to
this invention are disclosed in the following patents with
overlapping inventorship: U.S. Pat. No. 5,912,759, entitled
"Electrochemical Display Cell with Focused Field"; U.S. Pat. No.
5,930,023, entitled "Electrochemical Display and Timing Mechanism
with Migrating Electrolyte"; U.S. Pat. No. 6,136,468, entitled
"Electrochemical Cell with Deferred Assembly"; and U.S. Pat. No.
6,285,492, entitled "Interactive Electrochemical Displays". All of
these patents are hereby incorporated by reference.
[0027] FIG. 1 contains a diagram of an in-line press 10 intended
for flexographic printing, which is a form of transfer printing
involving a rotary letterpress with flexible printing plates. A web
12 is unrolled and advanced through two flexographic printing
stations 14 and 16 for printing successions of side-by-side
electrode patterns 32 and 34 shown in FIG. 2. Alternatively, the
web 12 could contain a pre-deposited electrode layer that is
patterned by a printed dielectric.
[0028] An electrolyte layer 36 in accordance with our invention can
be formulated as a flexographic ink that is laid down over the
electrodes 32 and 34 in a succession of patterns by a printing
station 18. A curing station 20, which preferably effects a
radiation cure by ultraviolet or ion beam radiation, transforms the
electrolytic ink into an electrolytic adhesive, such as a
pressure-sensitive adhesive.
[0029] Another web 22 is at least partially bonded together with
the web 12 by the electrolytic adhesive at a laminating station 24
to protect the active cell layers. The two webs 12 and 22
preferably function as low vapor transmission films, and the
laminating step can also include a heat-sealing operation that
further protects the active cell layers from loss of moisture or
exposure to the surrounding environment. Another portion (e.g., a
"wing") of the web 12 could be separated or folded and used in
place of the web 22. Subsequently, a die cutting station 26
separates the electrode and electrolyte patterns 32, 34, and 36
into individual electrochemical cells 30 or into groups of
individual electrochemical cells 30 that can be joined to form a
battery.
[0030] Various other layers can also be printed to complete the
cells 30 including layers forming a switch 38, as well as
dielectrics, conductors, collectors, and other adhesives. The cells
30 are arranged to provide internal functions such as display or
timing functions but can be connected to external circuits to also
function as low power sources or switches.
[0031] An electrolyte mix formulated for flexographic printing
includes the following components:
[0032] 0.76 gms thickener (Cyanamer N-300 LMW),
[0033] 38 gms water,
[0034] 8.5 gms electrolyte (KCI),
[0035] 15 gms glycerine,
[0036] 31 gms glacial acrylic acid, and
[0037] 1 gm cross-linker (Darocur 1173).
[0038] Mixing is done in the order indicated with the thickener
added in a ratio equal to about 2% of the water content to obtain a
desired viscosity for flexographic printing on press. The listed
thickener is a polyacrylamide available from Cytec Industries, Inc.
of West Patterson, N.J. More or less of the electrolyte solution
can be used to optimize ion conduction between the electrodes. The
Darocur 1173 cross-linker for the acrylic acid monomer (chemically
listed as 2hydroxy-2-methyl-1-phenyl-1-p- ropanone) is supplied by
Ciba Specialty Chemical Corporation of Tarrytown, N.Y.
[0039] The preferred curing operation involves exposing the
electrolyte layer 36 to ultraviolet light of approximately 1200
milli-joules per square centimeter using a "D" bulb on a Fusion
300S system. Most affected is the acrylic acid monomer that is
chemically transformed in the presence of the cross-linker into a
polymer functioning as a pressure-sensitive adhesive. The new
polymer structure provides a matrix within which KCI electrolyte is
embedded.
[0040] Additional layers of electrolyte layer can be printed over
the electrolyte layer 36 and alternately cured to build additional
thickness. Each additional layer is also preferably formulated
having low adhesive properties (low stickiness) consistent with the
requirements of flexographic or other transfer-printing techniques
and is preferably cured to exhibit the high adhesive properties
(high stickiness) of a pressure-sensitive adhesive prior to the
application of the next layer.
[0041] Another in-line flexographic press 50 shown in FIG. 3
includes two starting webs 52 and 54 that are unwound into separate
printing stations 56 and 58 for printing electrode patterns 82 and
84 of a succession of electrochemical cells 80 (shown in FIG. 4).
Similar printing stations 60 and 62 print electrolyte patterns 86
and 88 over the electrode patterns 82 and 84. Curing stations 64
and 66, which preferably expose the electrolyte patterns 86 and 88
to ultraviolet radiation, chemically transform the electrolyte of
the electrolyte patterns 86 and 88 into electrolytic adhesive.
[0042] The initial printing of the electrolyte patterns 86 and 88
on the printed electrode patterns 82 and 84 in a low-viscosity ink
enables the electrolyte to fill crevices, pores, and voids in the
printed electrode patterns 82 and 84, which can have rough or
granular surfaces. Some of the printed electrolyte flows into the
surface features of the printed electrolyte patterns 82 and 84
prior to curing so that, upon curing, the electrolyte patterns 86
and 88 are maintained in more intimate molecular contact with the
printed electrode patterns 82 and 84. The enhanced interfacial
contact improves bonding strength and provides more area for ion
transfers between the printed electrode and electrolyte patterns
82, 86 and 84, 88. In addition, curing the electrolyte patterns 86
and 88 already in contact with the electrode patterns 82 and 84
avoids the formation of surface barriers that could interfere with
the movement of ions between the printed electrode and electrolyte
patterns 82, 86 and 84, 88.
[0043] An inverter station 68 and a laminator 70 register and join
the two webs 52 and 54 together. The two cured electrolyte patterns
86 and 88 are joined together to complete a succession of ionically
conductive pathways between the electrode layers 82 and 84. Other
functions performed by the cured electrolyte patterns 86 and 88
include physically separating the electrode layers 82 and 84 and
bonding the two webs 52 and 54 together. The polymer form of the
cured electrolyte patterns 86 and 88 also holds the electrolyte in
place and reduces exposure to evaporation.
[0044] The two webs 52 and 54 could also be arranged as two lateral
portions of a single web that are separated or folded together in
advance of the laminator 70. Heat sealing is preferably used to
bond the two webs 52 and 54 or web portions together. Dielectric
adhesives or other bonding techniques could also be used to protect
the cell layers from undesirable interactions with the surrounding
environment.
[0045] A die cutter 72 divides the succession of printed cells into
individual electrochemical cells 80 or into groups of the
individual electrochemical cells 80. Other operations can also be
performed to mount the cells 80 on other laminates or substrates or
to connect the cells 80 to electrical loads. Other layers can also
be assembled to support cell functions including displaying,
switching, or timing functions.
[0046] The examples so far highlight the invention's special
applicability to flexographic printing of electrochemical cells.
Similar benefits can be obtained by other transfer-printing
techniques including conventional letterpress, gravure, and
lithography where a printed image is transferred from a printing
plate to a web or sheet. Some benefits even accrue to
screen-printing techniques, especially where monomer electrolyte
mixtures are advantageous for printing and polymer electrolyte
transformations are needed to perform additional functions.
[0047] Another printing technique especially suited to the printing
of electrolyte in accordance with our invention is injection
printing, which involves dispensing a metered volume of flowable
electrolyte into a pre-formed reservoir. The electrolyte conforms
to the shape of the reservoir. Curing transforms the electrolyte
into a more permanent shape.
[0048] FIG. 5 depicts an in-line press 100 employing both transfer
and injection printing techniques for making a succession of
electrochemical cells 130, which are further depicted in FIGS. 6
and 7. A web 102 is unrolled and advanced through two transfer
printing stations 104 and 106 for laying down pairs of electrodes
132 and 134 in a succession of parallel patterns along the web 102.
A screen printing station 108 applies a dielectric
pressure-sensitive adhesive layer 136 in a succession of patterns
surrounding the electrodes 132 and 134. A mask 112 is unrolled and
advanced through a die cutting station 114, which removes portions
of the mask 112 in a succession of patterns. A laminator 116
registers and joins the mask 112 to the web 102 through a bond
formed by the dielectric adhesive 136. The die cut patterns of the
mask 112 form parallel successions of reservoirs 138 and 140 that
expose portions of the two electrodes 132 and 134.
[0049] An injection printing station 118 injects metered volumes of
electrolyte 142 and 144 into the reservoirs 138 and 140 through a
pair of nozzles 120 and 121. The injected electrolyte 142 and 144
is formulated so that the injected volumes flow under the force of
gravity to conform with boundary shapes of the reservoirs 138 and
140. In other words, the injected electrolyte 142 and 144 has a
zero yield value. Also, the viscosity of the injected electrolyte
142 and 144 is low enough so that the injected electrolyte 142 and
144 reaches its imposed boundaries within the reservoirs 138 and
140 without undue delay that could significantly extend the press
100. The same rheological flow characteristics also provide
intimate contact between the injected electrolyte 142 and 144 and
the underlying electrodes 132 and 134, which form the bottoms of
the reservoirs 138 and 140.
[0050] Proceeding level until the reservoirs 138 and 140 are
completely filled, the web 102 advances through a curing station
122 that transforms the injected electrolyte 142 and 144 into
successions of more permanent shapes matching the shapes of the
reservoirs 138 and 140. Radiation curing with ultraviolet light is
preferred, but other curing methods can be used in conjunction with
different electrolyte formulations. The transformation can include
(a) transforming the electrolyte from a zero yield value to a
higher yield value, (b) transforming the electrolyte from a state
of lower viscosity to a state of higher viscosity, and (c)
transforming the electrolyte from a state of lower adhesiveness to
a state of higher adhesiveness, resulting for example in a
pressure-sensitive adhesive. Also, the electrolyte 142 and 144 is
preferably formulated to contain a monomer that is transformed into
a polymer that forms a matrix within which the electrolyte is
embedded. The earlier-described formulation for a flexographic ink
electrolyte can serve all of these purposes.
[0051] A combined folding and laminating station 124 folds the web
102 along its longitudinal axis 146 and presses the cured
electrolyte 142 and 144 into mutual contact to complete ionically
conductive pathways between the electrodes 132 and 134. A heat
sealing station 126 bonds the folded portions of the web 102
together and protects the electrolyte 142 and 144 from evaporation
or other undesirable interactions with the surrounding environment.
Another die cutting station 128 divides the advancing web 102 into
individual or groups of electrochemical cells 130.
[0052] Instead of folding the web 102 together, the web 102 could
be cut into separate sections prior to lamination or an additional
web could be printed and laminated together with the web 102. The
mask could also be formed from a lateral portion of the web 102 and
folded to form the required reservoirs. In place of the mask 112,
impressions could be made in the web 102 to provide similarly
shaped recesses for confining the injected electrolyte 142 and
144.
[0053] More operations can be formed along any of the in-line
presses 10, 50, or 100 to support additional functions of the
electrochemical cells 30, 80, or 130 or to relate the
electrochemical cells to other mountings, components, or circuits.
For example, printed conductors, such as carbon strips, can be
arranged to allow completion of electronically conductive pathways
within or between the cells. The electrodes could also be printed
on a carbon base, which can also function as a conductive
pathway.
* * * * *