U.S. patent application number 09/775619 was filed with the patent office on 2001-08-02 for method for manufacturing solid polymer electrolyte/electrode composites, battery produced using the method and method for producing the same.
Invention is credited to Hirata, Motoyuki, Moriguchi, Toshikazu, Yotsuyanagi, Junji.
Application Number | 20010010252 09/775619 |
Document ID | / |
Family ID | 26686265 |
Filed Date | 2001-08-02 |
United States Patent
Application |
20010010252 |
Kind Code |
A1 |
Hirata, Motoyuki ; et
al. |
August 2, 2001 |
Method for manufacturing solid polymer electrolyte/electrode
composites, battery produced using the method and method for
producing the same
Abstract
Disclosed are a method for manufacturing a solid polymer
electrolyte film/electrode composite, in which a porous electrode
made from an electochemically active substance is used as an
electrode and the pressure inside the porous electrode is reduced
in order to fix the solid polymer electrolyte (SPE) film or
pre-solid polymer electrolyte (pre-SPE) film to the porous
electrode, a battery obtained by impregnating the electrode in the
solid polymer electrolyte film/electrode composite with an
electrolytic solution under reduced pressure and a method for
producing such. The invention provides a thin, uniform film-shaped
solid polymer electrolyte/electrode composite with ease. The
battery fabricated with the composite is free of defects such as
short, has high performance and, hence, is useful.
Inventors: |
Hirata, Motoyuki; (Kanagawa,
JP) ; Yotsuyanagi, Junji; (Kanagawa, JP) ;
Moriguchi, Toshikazu; (Tokyo, JP) |
Correspondence
Address: |
SUGHRUE, MION, ZINN, MACPEAK & SEAS, PLLC
2100 PENNSYLVANIA AVENUE, N.W.
WASHINGTON
DC
20037-3213
US
|
Family ID: |
26686265 |
Appl. No.: |
09/775619 |
Filed: |
February 5, 2001 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
09775619 |
Feb 5, 2001 |
|
|
|
09014572 |
Jan 28, 1998 |
|
|
|
6210513 |
|
|
|
|
60056267 |
Aug 29, 1997 |
|
|
|
Current U.S.
Class: |
156/307.1 |
Current CPC
Class: |
H01M 4/13 20130101; H01M
10/0565 20130101; Y02E 60/10 20130101; H01M 6/40 20130101; H01M
10/052 20130101; H01M 4/04 20130101; Y10T 428/249953 20150401; H01M
6/188 20130101; H01M 10/0525 20130101 |
Class at
Publication: |
156/307.1 |
International
Class: |
B32B 031/26 |
Claims
What is claimed is:
1. A method for manufacturing a composite of a solid polymer
electrolyte film and a thin film-shaped electrode, comprising the
steps of: providing a thin film-shaped porous electrode comprising
an electrochemically active substance; and reducing the pressure
inside the porous electrode.
2. A method for manufacturing a composite of a solid polymer
electrolyte film and a thin film-shaped electrode, comprising the
steps of: coating on an electrode surface of said thin film-shaped
porous electrode a polymerizable compound which is converted to a
solid polymer electrolyte or a pre-solid polymer electrolyte upon
polymerization; and reducing the pressure inside the porous
electrode after superposing the electrode surface coated with the
polymerizable compound onto said solid polymer electrolyte
film.
3. The method for manufacturing a composite of a solid polymer
electrolyte film and a thin film-shaped electrode as claimed in
claim 1 or 2, wherein said solid polymer electrolyte film has an
ion conductivity at room temperature of 10.sup.-5 S/cm or more.
4. The method for manufacturing a composite of a solid polymer
electrolyte film and a thin film-shaped electrode as claimed in any
one of claims 1 to 3, wherein said solid polymer electrolyte film
contains a cross-linking polymer having a urethane bond and an
oxyalkylene group.
5. The method for manufacturing a composite of a solid polymer
electrolyte film and a thin film-shaped electrode as claimed in
claim 2, wherein said polymerizable compound coated on the
electrode has a urethane bond and an oxyalkylene group.
6. The method for manufacturing a composite of a solid polymer
electrolyte film and a thin film-shaped electrode as claimed in any
one of claims 1 to 5, wherein said solid polymer electrolyte film
is obtained by polymerizing a composition comprising a solvent
having dissolved therein a polymerizable compound.
7. The method for manufacturing a composite of a solid polymer
electrolyte film and a thin film-shaped electrode as claimed in any
one of claims 1 to 5, wherein said solid polymer electrolyte film
is obtained by polymerizing a composition comprising a solvent
containing an electrolyte salt having dissolved therein a
polymerizable compound.
8. A method for manufacturing a composite of a solid polymer
electrolyte film and a thin film-shaped electrode, comprising the
steps of: coating a polymerizable compound which converts to a
solid polymer electrolyte or a pre-solid polymer electrolyte upon
polymerization on an electrode surface of a laminate film
comprising a film base material and a film-shaped porous electrode
on the film base material; reducing the pressure inside the
electrode after superposing the surface coated with the
polymerizable compound onto said solid polymer electrolyte film;
and peeling off said film base material.
9. The method for manufacturing a composite of a solid polymer
electrolyte film and a thin film-shaped electrode, as claimed in
claim 8, further comprising the step of polymerizing the
polymerizable compound after the step of reducing the pressure
inside the electrode.
10. The method for manufacturing a composite of a solid polymer
electrolyte film and a thin film-shaped electrode, as claimed in
claim 8 or 9, wherein the film base material has a metal or metal
oxide coating, on which said film-shaped porous electrode is
provided to form a laminate film.
11. A method for producing a battery, comprising the step of:
providing a composite of a solid polymer electrolyte film and an
electrode obtained by the method as claimed in any one of claims 1
to 10; and impregnating under reduced pressure the electrode in
said composite with an electrolytic solution.
12. The method for producing a battery as claimed in claim 11,
wherein the electrolytic solution comprises a polymerizable
compound and an electrolyte salt and the polymerizable compound is
polymerized to cure after the impregnation under reduced
pressure.
13. A method for producing a battery, comprising the step of:
providing a composite of a solid polymer electrolyte film
containing no electrolyte salt and an electrode as claimed in claim
6; and impregnating the electrode of said composite with an
electrolytic solution under reduced pressure.
14. The method for producing a battery as claimed in claim 13,
wherein the electrolytic solution comprises a polymerizable
compound and an electrolyte salt and the polymerizable compound is
polymerized to cure after the impregnation under reduced
pressure.
15. A method for producing a battery, comprising the step of:
providing a composite of a solid polymer electrolyte film
containing an electrolyte salt and an electrode as claimed in claim
7; and impregnating the electrode of said composite with an
electrolytic solution which has a concentration of an electrolyte
salt greater than a concentration at which the electrolytic
solution has a maximum ion conductivity.
16. The method for producing a battery as claimed in claim 15,
wherein the electrolytic solution comprises a polymerizable
compound and an electrolyte salt and the polymerizable compound is
polymerized to cure after the impregnation under reduced
pressure.
17. A battery obtained by the method as claimed in any one of
claims 11 to 16.
Description
BACKGROUND ART
[0001] The present invention relates to a method for manufacturing
a composites of a solid polymer electrolyte and an electrode, and
also relates to a battery produced using the manufacturing method
and to a method for producing a battery using the manufacturing
method.
DESCRIPTION OF THE RELATED ART
[0002] A solid polymer electrolyte (hereinafter sometimes
abbreviated as "SPE") is a polymer substance containing an
electrolyte salt which polymer substance exhibits high ionic
conductivity in the solid state and development thereof is being
driven for the purpose of the application to various sensors, fuel
batteries, coming generation batteries, photoelectric cells and
electrochromic elements.
[0003] In order to impart high ionic conductivity to SPE, lower
glass transition temperatures are more advantageous. However, if
such is the case, the film strength is reduced and the SPE film
disadvantageously becomes difficult to handle industrially. While
there has been proposed a method of adding an organic solvent to
SPE, this incurs a reduction in the strength thereof and the
handling of the SPE film becomes even more difficult.
[0004] Accordingly, in order to laminate SPE on an electrode, a
method of coating an SPE prepolymer directly on the electrode
surface and then curing the polymer by cross-linking might be
considered promising. However, the coating method is
disadvantageous in that the thickness of SPE layer is difficult to
control and homogeneous thin films can be hardly obtained.
[0005] To cope with this, a method of forming SPE into a film and
adhering the film to an electrode is being attempted.
[0006] However, this method has problems in that the SPE film is
generally weak in the strength and difficult to adhere to the
electrode without any breakage. Moreover, SPE film containing an
electrolytic solution is highly hygroscopic and can be difficultly
adhered to the electrode while maintaining its low water
content.
SUMMARY OF THE INVENTION
[0007] Under these circumstances, the present invention has been
made and the objects of the present invention are to provide a
method for manufacturing a composite of a solid polymer electrolyte
and an electrode which allows for fixation of a film comprising an
SPE film or a film made from an SPE polymer containing no
electrolyte (hereafter, abbreviated as pre-SPE) (in the present
invention, the term "solid polymer electrolyte film" includes the
both films above) to an electrode in a simple and easy manner and
to provide a battery produced using such a manufacturing method and
a method for producing a battery using the method.
[0008] As a result of extensive investigations, the present
inventors have found that the above-described objects can be
attained by fixing a solid polymer electrolyte film to a porous
electrode while reducing the pressure inside the porous electrode,
fabricating a battery, and then impregnating the electrode in a
solution comprising an electrolyte salt having high hygroscopic
property. The present invention has been accomplished based on
these findings.
[0009] By the method for manufacturing a composite of a solid
polymer electrolyte film and an electrode according to the present
invention, there can easily be obtained a thin composite having a
uniform thickness and the solid battery obtained with this
composite is free of short or the like, has high performance and is
useful.
[0010] That is, the present invention provides a method for
manufacturing a solid polymer electrolyte film/electrode composite,
the method comprising fixing a solid polymer electrolyte film to a
porous electrode comprising an electrochemical active substance
while reducing the pressure inside the porous electrode.
[0011] Also, the present invention provides a method for producing
a battery, the method comprising impregnating the electrode of the
solid polymer electrolyte film/electrode composite obtained by the
method described above with an electrolytic solution under reduced
pressure and a battery obtained by the method.
[0012] That is, the present invention relates to the method for
manufacturing a solid polymer electrolyte film/electrode
composites, to the method for producing a battery using the
composites and to a battery produced by the production method as
follows.
[0013] 1) A method for manufacturing a composite of a solid polymer
electrolyte film and a thin film-shaped electrode, comprising the
steps of: providing a thin film-shaped porous electrode comprising
an electrochemically active substance; and reducing the pressure
inside the porous electrode.
[0014] 2) A method for manufacturing a composite of a solid polymer
electrolyte film and a thin film-shaped electrode, comprising the
steps of: coating on an electrode surface of the thin film-shaped
porous electrode a polymerizable compound which is converted to a
solid polymer electrolyte or a pre-solid polymer electrolyte upon
polymerization; and reducing the pressure inside the porous
electrode after superposing the electrode surface coated with the
polymerizable compound onto the solid polymer electrolyte film.
[0015] 3) The method for manufacturing a composite of a solid
polymer electrolyte film and a thin film-shaped electrode as
described in 1) or 2) above, wherein the solid polymer electrolyte
film has an ion conductivity at room temperature of 10.sup.-5 S/cm
or more.
[0016] 4) The method for manufacturing a composite of a solid
polymer electrolyte film and a thin film-shaped electrode as
described in any one of 1) to 3) above, wherein the solid polymer
electrolyte film contains a cross-linking polymer having a urethane
bond and an oxyalkylene group.
[0017] 5) The method for manufacturing a composite of a solid
polymer electrolyte film and a thin film-shaped electrode as
described in 2) above, wherein the polymerizable compound coated on
the electrode has a urethane bond and an oxyalkylene group.
[0018] 6) The method for manufacturing a composite of a solid
polymer electrolyte film and a thin film-shaped electrode as
described in any one of 1) to 5) above, wherein the solid polymer
electrolyte film is obtained by polymerizing a composition
comprising a solvent having dissolved therein a polymerizable
compound.
[0019] 7) The method for manufacturing a composite of a solid
polymer electrolyte film and a thin film-shaped electrode as
described in any one of 1) to 5) above, wherein the solid polymer
electrolyte film is obtained by polymerizing a composition
comprising a solvent containing an electrolyte salt having
dissolved therein a polymerizable compound.
[0020] 8) A method for manufacturing a composite of a solid polymer
electrolyte film and a thin film-shaped electrode, comprising the
steps of: coating a polymerizable compound which converts to a
solid polymer electrolyte or a pre-solid polymer electrolyte upon
polymerization on an electrode surface of a laminate film
comprising a film base material and a film-shaped porous electrode
on the film base material; reducing the pressure inside the
electrode after superposing the surface coated with the
polymerizable compound onto the solid polymer electrolyte film; and
peeling off the film base material.
[0021] 9) The method for manufacturing a composite of a solid
polymer electrolyte film and a thin film-shaped electrode, as
described in 8) above, further comprising the step of polymerizing
the polymerizable compound after the step of reducing the pressure
inside the electrode.
[0022] 10) The method for manufacturing a composite of a solid
polymer electrolyte film and a thin film-shaped electrode, as
described in 8) or 9) above, wherein the film base material has a
metal or metal oxide coating, on which the film-shaped porous
electrode is provided to form a laminate film.
[0023] 11) A method for producing a battery, comprising the step
of: providing a composite of a solid polymer electrolyte film and
an electrode obtained by the method as described in any one of 1)
to 10) above; and impregnating under reduced pressure the electrode
in the composite with an electrolytic solution.
[0024] 12) The method for producing a battery as described in 11)
above, wherein the electrolytic solution comprises a polymerizable
compound and an electrolyte salt and the polymerizable compound is
polymerized to cure after the impregnation under reduced
pressure.
[0025] 13) A method for producing a battery, comprising the step
of: providing a composite of a solid polymer electrolyte film
containing no electrolyte salt and an electrode as described in 6)
above; and impregnating the electrode of the composite with an
electrolytic solution under reduced pressure.
[0026] 14) The method for producing a battery as described in 13)
above, wherein the electrolytic solution comprises a polymerizable
compound and an electrolyte salt and the polymerizable compound is
polymerized to cure after the impregnation under reduced
pressure.
[0027] 15) A method for producing a battery, comprising the step
of: providing a composite of a solid polymer electrolyte film
containing an electrolyte salt and an electrode as described in 7)
above; and impregnating the electrode of the composite with an
electrolytic solution which has a concentration of an electrolyte
salt greater than a concentration at which the electrolytic
solution has a maximum ion conductivity.
[0028] 16) The method for producing a battery as described in 15)
above, wherein the electrolytic solution comprises a polymerizable
compound and an electrolyte salt and the polymerizable compound is
polymerized to cure after the impregnation under reduced
pressure.
[0029] 17) A battery obtained by the method as described in any one
of 11) to 16) above.
DETAILED DESCRIPTION
[0030] The porous electrode used in the present invention comprises
an electrochemical active substance. Specific examples of the
electrochemical active substance include metal oxides such as
cobalt oxide, manganese oxide, vanadium oxide, nickel oxide and
molybdenum oxide, metal sulfides such as molybdenum sulfide,
titanium sulfide and vanadium sulfide, electrically conductive
polymers such as polyaniline, polyacetylene and derivatives
thereof, polyparaphenylene and a derivative thereof, polypyrrole
and a derivative thereof, and polythienylene and a derivative
thereof, and carbon materials such as natural graphite, artificial
graphite, vapor phase processed graphite, petroleum coke, coal
coke, graphite fluoride, pitch-base carbon and polyacene.
[0031] The SPE film or pre-SPE film used in the present invention
is obtained by polymerizing a polymerizable compound-containing
solution composition which contains a polymerizable compound and at
least a solvent.
[0032] In the present invention, the polymerizable
compound-containing solution composition for the SPE film which can
be used includes a mixture of a solvent containing an electrolyte
and a polymerizable compound, and preferably used is a
polymerizable compound-containing solution composition for the
pre-SPE that comprises a mixture of a solution containing no
electrolyte and a polymerizable compound. This is because while the
former provides a composite of a solid polymer electrolyte film and
electrode only by polymerizing and fixing the film to the
electrode, there occurs a problem due to the hygroscopic property
of the electrolyte. In the case of the latter, the composite of a
pre-SPE film and an electrode is fabricated and then the composite
is impregnated with an electrolytic solution to give a composite of
a solid polymer electrolyte film and electrode. This, however,
causes no such problem and, hence, is advantageous.
[0033] The polymerization reaction of the polymerizable
compound-containing solution composition can be performed using
active light beams such as visible light, ultraviolet ray, electron
beam, .gamma. ray and X ray, as well as the thermal polymerization.
The polymerizable compound includes a functional monomer or
oligomer having at least one hetero atom. Specific examples thereof
include (meth)acrylic esters and di(meth)acrylic esters each having
an oxyalkylene chain, such as .omega.-methyloligooxyethyl
methacrylate; alkyl(meth)acrylates such as methyl methacrylate and
n-butyl acrylate; (meth)acrylamide-base compounds such as
acrylamide, methacrylamide, N,N-dimethylacrylamide,
N,N-dimethylmethacrylamide, acryloylmorpholine,
methacryloylmorpholine and N,N-dimethylaminopropyl (meth)
acrylamide; N-vinylamide-base compounds such as N-vinylacetamide
and N-vinylformamide; alkyl vinyl ethers such as ethyl vinyl ether;
polyfunctional (meth)acrylates such as trimethylolpropane
(meth)acrylate, pentaerythritol penta(meth)acrylate and
dipentaerythritol hexa (meth) acrylate; and various urethane
acrylate prepolymers such as phenylglycidyl ether acrylate
hexamethylene diisocyanate urethane prepolymer, phenylglycidyl
ether acrylate isophorone diisocyanate urethane prepolymer.
[0034] Further, a polymerizable compound which has polymerizable
functional groups comprising a urethane bond and an oxyalkylene
group, represented by the following formula can be used.
CH.sub.2=C (R.sup.1)CO
[O(CH.sub.2).sub.x(CH(CH.sub.3)).sub.y].sub.zNHCOO-- -R.sup.2--
[0035] wherein R.sup.1 represents hydrogen or an alkyl group,
R.sup.2 represents a divalent organic group containing an
oxyalkylene group, which may have a linear, branched or cyclic
structure and may contain an atom other than carbon, hydrogen and
oxygen, X and Y each independently represents 0 or an integer of
from 1 to 5, and Z represents 0 or an integer of from 1 to 10,
provided that when X is 0 and Y is 0, Z is 0; (CH.sub.2) and
(CH(CH.sub.3)) may be irregularly disposed; and R.sup.1, R.sup.2,
the values of X, Y and Z in one unit may be independent from those
in another unit within one molecule and do not have to be the same
among units.
[0036] Specific examples of the compound represented by the formula
above include .omega.-methyloligooxyethyl N-methacryloylcarbamate
and .omega.-methyloligooxyethyl methacryloyloxyethylcarbamate.
These polymerizable compounds may be used individually or in
combination of two or more thereof.
[0037] Among the above-described polymerizable compounds, the
compounds having an urethane bond and an oxyalkylene group are
preferred, and examples thereof include oxyalkylene
chain-containing urethane (meth)acrylate, urethane acrylate,
oxyalkylene chain-containing (meth)acrylic ester and
(meth)acrylamide-base compounds, with oxyalkylene chain-containing
urethane (meth)acrylate being more preferred.
[0038] In order to obtain a cross-linked form of the polymer, at
least one polyfunctional polymerizable compound can be used in
combination as a copolymer component. Examples of the cross-linking
polyfunctional compound which can be copolymerized include a
diacrylate or dimethacrylate of polyalkylene glycol having a
molecular weight of 1,000 or less (e.g., oligoethylene oxide,
polyethylene oxide, oligopropylene oxide, polypropylene oxide), a
diacrylate or dimethacrylate of linear, branched or cyclic alkylene
glycol having from 2 to 20 carbon atoms (e.g., ethylene glycol,
propylene glycol, trimethylene glycol, 1,4-butanediol,
1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol,
1,9-nonanediol, 1,10-decanediol, cyclohexane-1,4-diol), a
polyfunctional acrylate or methacrylate compound resulting from
displacing two or more OH groups of a linear, branched or cyclic
polyhydric alcohol having 3 or more OH groups (e.g., glycerin,
trimethylolpropane, pentaerythritol, sorbitol, glucose, mannitol),
with an acryloyloxy group or a methacryloyloxy group, such as
trimethylolpropane triacrylate (TMPTA), trimethylolpropane
trimethacrylate (TMPTM), pentaerythritol triacrylate (PETA),
pentaerythritol trimethacrylate (PETM), dipentaerythritol
hexaacrylate (DPHA) and dipentaerythritol hexamethacrylate (DPHM),
a polyfunctional acrylate compound having a molecular weight of
2,000 or less resulting from displacing two or more OH groups of
the above-described polyhydric alcohol with an acryloyloxy-oligo
(or poly) ethyleneoxy (or propyleneoxy) group, a polyfunctional
methacrylate compound having a molecular weight of 2,000 or less
resulting from displacing two or more OH groups of the
above-described polyhydric alcohol with a methacryloyloxy-oligo (or
poly) ethyleneoxy (or propyleneoxy) group, an aromatic urethane
acrylate (or methacrylate) compound such as reaction product of
tolylene diisocyanate with hydroxyalkyl acrylate (or methacrylate)
(e.g., hydroxyethyl acrylate), an aliphatic urethane acrylate (or
methacrylate) compound such as reaction product of an aliphatic
diisocyanate (e.g., hexamethylene diisocyanate) with hydroxyalkyl
acrylate (methacrylate) (e.g., hydroxyethyl methacrylate), a
divinyl compound such as divinylbenzene, divinyl ether and
divinylsulfone, and a diallyl compound such as diallyl phthalate
and diallyl carbonate.
[0039] The SPE for use in the present invention usually has an ion
conductivity of 10.sup.-5 S/cm or more, preferably from
5.times.10.sup.-5 to 10.sup.-1 S/cm.
[0040] Examples of the electrolyte salt include LiClO.sub.4,
LiBF.sub.4, LiAsF.sub.6, LiCF.sub.3SO.sub.3, LiPF.sub.6, LiN
(CF.sub.3SO.sub.3).sub.2- , LiI, LiBr, LISCN, NaI,
Li.sub.2B.sub.10Cl.sub.10 LiCF.sub.3CO.sub.2, NaBr, NaSCN, KSCN,
MgCl.sub.2, Mg(ClO.sub.4).sub.2, (CH.sub.3).sub.4NBF.sub.4,
(CH.sub.3).sub.4NBr, (C.sub.2H.sub.5).sub.4NCl- O.sub.4,
(C.sub.2H.sub.5).sub.4NI, (C.sub.3H.sub.7).sub.4NBr, (n-C.sub.
4H.sub.9).sub.4NClO.sub.4, (n--C.sub.4H.sub.9).sub.4NI and
(n-C.sub.5H.sub.11) .sub.4NI. Among these, a Li salt such as
LiBF.sub.4, LiClO.sub.4 and LiPF.sub.6, and a quaternary ammonium
salt such as (C.sub.2H.sub.5).sub.4NClO.sub.4 are preferred. The
ratio of the electrolyte salt blended is generally from 0.1 to 70
parts by weight, preferably from 1 to 50 parts by weight, more
preferably from 1 to 30 parts by weight, per 100 parts by weight of
the polymerizable compound.
[0041] The solvent for the polymerizable compound-containing
solution composition for use in the present invention include
tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane,
4,4-dimethyl-1,3-dioxane, .gamma.-butyrolactone, diethyl carbonate,
dimethyl carbonate, methyl ethyl carbonate, ethylene carbonate,
propylene carbonate, butylene carbonate, sulfolane,
3-methylsulfolane, t-butyl ether, i-butyl ether,
1,2-dimethoxyethane, 1,2-diethoxymethoxyethane, methyldiglyme,
methyltriglyme, methyltetraglyme, ethylglyme and ethyldiglyme.
These may be used individually or in combination of two or more
thereof.
[0042] To the polymerizable compound-containing solution
composition may be added a polymerization initiator. Examples of
the polymerization initiator include a radical thermal
polymerization initiator such as azobisisobutyronitrile and benzoyl
peroxide, a radical photopolymerization initiator such as benzyl
methyl ketal and benzophenone, a cation polymerization catalyst
such as a protonic acid (e.g., CF.sub.3COOH) and a Lewis acid
(e.g., BF.sub.3, AlCl.sub.3), and an anion polymerization catalyst
such as butyl lithium, sodium naphthalene and lithium alkoxide.
[0043] In the present invention, there can be used a laminate film
which comprises a base material and a film form porous electrode
provided thereon. After a SPE film or pre-SPE film is fixed to the
electrode surface of the laminate film, the base material is peeled
off in the final step to fabricate an SPE/electrode composite.
[0044] The film base material used herein is not particularly
limited and examples thereof include polyolefins such as
polyethylene and polypropylene, and general thermoplastic resins
such as polyvinyl chloride, polyester and polyamide. The film may
be either non-stretched or stretched. The film base material
generally has a thickness of from 1 to 5,000 .mu.m, preferably from
1 to 1,000 .mu.m, more preferably from 5 to 100 The laminate film
for use in the present invention is obtained by laminating the
above-described SPE or pre-SPE film on a film base material. The
SPE is laminated by a known coating method such as a doctor knife
method and then polymerized to cure by thermal polymerization or
the like. Use of a thin film such as a metal or metal oxide formed
as by vapor deposition on the surface of the film base material is
preferred in view of wettability and peelability. The SPE film of
the laminate film usually has a thickness of from 1 to 1,000 .mu.m,
preferably from 1 to 300 .mu.m, more preferably from 1 to 50
.mu.m.
[0045] The method for manufacturing a solid polymer electrolyte
film/electrode composite according to the present invention is
featured by superposing a surface of SPE film or pre-SPE film of
the laminate film onto a surface of the porous electrode and then
reducing the pressure inside the porous electrode for fixation. The
pressure is reduced, for example, by a method such that a porous
electrode is placed on a gas permeable material such as sintered
metal and the other surface side of the gas permeable material is
decompressed by means of a vacuum pump.
[0046] The battery of the present invention is obtained by
impregnating the solid polymer electrolyte film/electrode composite
fabricated according to the above-described method with an
electrolytic solution under reduced pressure.
[0047] As the electrolytic solution can be used a solution obtained
by dissolving an electrolyte salt in a solvent. If desired, a
solution containing the above-described polymerizable compound and
polymerization initiator as well as the electrolyte salt may be
used so that the electrolytic solution after the impregnation can
be cured by the method described above such as thermal
polymerization.
[0048] Taking account of the diffusion of the electrolyte salt into
the SPE film layer or the pre-SPE film layer upon impregnation of
the solid polymer electrolyte film with the electrolytic solution,
the concentration is preferably set higher than the electrolyte
concentration necessary for giving a maximum ion conductivity (in
general, about 1 mol/l).
BEST MODE FOR CARRYING OUT THE INVENTION
[0049] The present invention is described in greater detail below
by referring to examples. However, the present invention is not
limited to the following examples.
EXAMPLE 1
[0050] To 100 parts by weight of Mixture A containing 33 wt % of a
polymerizable compound shown below as a pre-SPE polymerizable
compound-containing solution composition: 1
[0051] (wherein m is 25, is hydrogen:methyl group 7:3 by mol) and
67 wt % of a solvent (a mixture of 75 wt % of ethylene carbonate
and 25 wt % of propylene carbonate), 0.25 part by weight of a
polymerization initiator (a mixture of 50% by weight of
1-hydroxycyclohexyl phenyl ketone and 50% by weight of benzophenone
(trade name: Irgacure 500, produced by Ciba Geigy) was added to
prepare a mixed solution.
[0052] A 12 .mu.m-thick polyester film having evaporated alumina on
one surface thereof was used as the film base material and the
solution composition prepared above was coated on the alumina
evaporated surface of the base material by means of a coater to
have a thickness of 30 .mu.m. Thereafter, ultraviolet rays were
irradiated on the mixed solution composition thus coated to cure
the solution composition by cross-linking, thereby obtaining a
pre-SPE laminated film. A 30 .mu.m-thick oriented polypropylene
(OPP) film was superposed thereon to prepare a three-layer
film.
[0053] An electrode having a size slightly smaller than the film
base material and obtained by coating a mixture of natural graphite
polymer with a binder of 3 wt % polyvinylidene fluoride (PVDF) on a
15 .mu.m-thick copper foil to have a thickness of 85 .mu.m was used
as the negative electrode. The electrode was placed on a 2 mm-thick
stainless steel-made sintered plate, the surface from which the OPP
film of the three-layer film had been removed was superposed
thereon, and the back surface of the sintered plate was
decompressed by means of a vacuum pump. The adhesion of the pre-SPE
film to the electrode was confirmed and then, the polyester film
was peeled off while continuing the decompression to fix only the
pre-SPE film onto the electrode.
[0054] A positive electrode obtained by coating lithium cobalt
(LiCoO.sub.2) powder on a 25 .mu.m-thick aluminum foil to have a
thickness of 100 .mu.m was superposed on the pre-SPE film described
above in the same manner as above to fabricate a battery.
[0055] The battery thus fabricated was dipped in a solution
obtained by adding 500 ppm of a thermal polymerization initiator
(bis(4-t-butylcyclohexyl) peroxycarbonate, Perloyl TCP produced by
Nippon Oils and Fats KK) to Mixed Solution B which was prepared by
mixing a solvent (diethyl carbonate:ethylene carbonate=1:1)
containing 10 parts by weight of LiClO.sub.4 as an electrolyte salt
per 100 parts by weight of the solvent, with the polymerizable
compound prepared above at a mixing ratio of 6:1, and then
impregnated therewith under reduced pressure by means of a vacuum
pump. Thereafter, the battery impregnated was subjected to thermal
polymerization at a temperature of 80.degree. C. for 30 minutes to
cure, thereby manufacturing a solid battery.
[0056] The battery (size: 2 cm.times.2 cm) obtained was charged and
discharged repeatedly 10 times under conditions such that the
working voltage was from 2.5 to 4.2 V and the electric current was
0.2 mA/cm.sup.2. As a result, the maximum discharge capacity was
9.8 mAh.
[0057] Further, the battery was charged and discharged repeatedly
10 times at an electric current of 2 mA/cm.sup.2 and then, the
maximum discharge capacity was 8.9 mAh.
EXAMPLE 2
[0058] In the same manner as in Example 1 were prepared a
three-layer film composed of a polyester film base material and a
pre-SPE layer and an OPP layer laminated on the film base material
and an electrode composed of a copper foil-graphite negative
electrode and having a size slightly smaller than the film base
material.
[0059] The electrode was placed on a stainless steel-made sintered
plate while the OPP film was removed from the three-layer film. On
an exposed SPE surface was coated Mixture A of Example 1 to a
thickness of 5 .mu.m. Then, the both members were superposed one on
another so that the surface coated with Mixture A contacted the
negative electrode surface. Then, the back surface of the sintered
plate was decompressed using a vacuum pump. After confirming the
adhesion of the pre-SPE film to the electrode, the resulting
laminate was irradiated with ultraviolet rays from above the
polyester film to cure Mixture A to completely adhere the pre-SPE
film to the electrode. Subsequently, the polyester film was removed
while continuing the decompressing, and only the pre-SPE film was
fixed on the electrode.
[0060] On the electrode/pre-SPE composite thus obtained was
superposed a positive electrode having the same structure as that
in Example 1 and impregnated with the same polymerizable
electrolytic solution as used in Example 1, followed by thermal
polymerization for fixation to fabricate a solid battery.
[0061] The battery thus obtained was charged and discharged in the
same manner as in Example 1 and then, the maximum discharge
capacities were 9.5 mAh and 8.6 mAh, respectively.
EXAMPLE 3
[0062] A battery was manufactured in the same manner as in Example
1 except for using a mixed solution obtained by adding 10 parts by
weight of LiClO.sub.4 and 0.25 part by weight of Irgacure 500 to
100 parts by weight of Mixture A. The battery obtained was charged
and discharged in the same manner as in Example 1 and then, the
maximum discharge capacities were 9.9 mAh and 9.0 mAh,
respectively.
COMPARATIVE EXAMPLE 1
[0063] In Example 2, decompression was not performed. As a result,
the adhesive strength between the SPE layer and the electrode was
weak and the SPE could not be adhered onto the electrode.
COMPARATIVE EXAMPLE 2
[0064] In Example 2, the electrolyte was coated to have a thickness
of 30 .mu.m and the decompression was not performed. As a result,
on peeling off the polyester film, the negative electrode was
readily peeled off together from the copper foil and adhering was
difficultly achieved. A battery barely succeeded in the adhering
was evaluated on the performance and then found to have inferior
capability such that the maximum discharge capacities were 9.4 mAh
and 4.8 mAh, respectively.
* * * * *