JP2003217983A - Electric double-layer capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric double-layer capacitor using a polarizing electrode which will not block the polymerization reaction of a polymer electrolyte, in an electric double-layer capacitor with high safety which uses the polymer electrolyte. <P>SOLUTION: In an electric double-layer capacitor, polarizing electrodes containing an active carbon species are disposed opposite to each other via a polymer electrolyte. The electric double-layer capacitor includes a polymer obtained by reacting a piperazine derivative, in which the pH of the active carbon species is in the range of 4 to 9, and the polymer electrolyte is represented by Formula (A) (refer to Chemical Formula 1), a hydrosilylated compound represented by Formula (B) (refer to Chemical Formula 2, and a compound represented by Formula (D). <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an electric double layer capacitor.

[0002]

2. Description of the Related Art An electric double layer capacitor utilizing an electric double layer generated at an interface between a polarizable electrode and an electrolytic solution is used as a backup power source for a personal computer, a hybrid vehicle power source,
It is used as a power source for starting the starter motor.

The electric double layer capacitor has a structure in which an electrolytic solution is filled between polarizable electrodes facing each other through a separator in a cell. As the electrolytic solution, an aqueous electrolytic solution such as a sulfuric acid aqueous solution or a non-aqueous electrolytic solution is used. An electric double layer capacitor using a non-aqueous electrolyte may vaporize the non-aqueous electrolyte in a high temperature atmosphere, increase the internal pressure, deform the shape of the capacitor and reduce the characteristics, or cause a fire. It may happen. Further, although the electric double layer capacitor using the aqueous electrolytic solution is superior in heat resistance to the one using the non-aqueous electrolytic solution, when the cell is damaged by external pressure, the acidic electrolytic solution leaks out. There was a risk. Therefore, in order to improve the safety of the electric double layer capacitor, an electric double layer capacitor using a polymer electrolyte such as a gel electrolyte or an all solid electrolyte containing an electrolytic solution has been proposed.

The polarizable electrodes of the electric double layer capacitor include
Carbon fiber, fibrous activated carbon, fine powder activated carbon or the like is used. The activated carbon has fine pores formed by the activation treatment, but impurities and the like may remain on the surface thereof. One of the methods for producing electric double layer capacitors using polymer electrolytes is to incorporate electrodes, polymer electrolyte raw materials, etc. into a cell for capacitors and polymerize them.However, impurities remaining on the surface of activated carbon species hinder the polymerization reaction. was there. Further, when an electric double layer capacitor manufactured by incorporating a prepolymerized polymer electrolyte into a cell is continuously used, the impurities on the surface of the activated carbon cause
In some cases, the polymer electrolyte was decomposed and liquid leakage occurred.

[0005]

An object of the present invention is to provide a highly safe electric double layer capacitor using a polymer electrolyte without deteriorating the polymerization reaction of the polymer electrolyte and decomposing the polymer electrolyte. An object is to provide an electric double layer capacitor using a non-polarizable electrode.

It is another object of the present invention to provide an electric double layer capacitor that operates stably for a long period of time by using a polymer electrolyte that is not easily affected by decomposition of impurities on the surface of activated carbon species and inhibition of polymerization.

[0007]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that in an electric double layer capacitor in which polarizable electrodes containing activated carbon species face each other through a polymer electrolyte. , The pH of the activated carbon species is 4-9
And the polymer electrolyte has the formula (A)

[Chemical 4] [In the formula, R ^1's each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 18 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms;
R ^2's are independently of each other a substituted or unsubstituted alkylene group having 1 to 18 carbon atoms, a substituted or unsubstituted saturated or unsaturated cycloalkylene group having 6 to 20 carbon atoms, a substituted or unsubstituted 6 carbon atoms. To 20 arylene group, substituted or unsubstituted arylalkylene group having 7 to 21 carbon atoms, substituted or unsubstituted arylenealkylene group having 7 to 21 carbon atoms, substituted or unsubstituted 8 to 22 carbon atoms
Derived from an arylene bis (alkylene) group, a dialkyl (poly) silylene group, a diaryl (poly) silylene group, a heteroatom-containing organic group having 1 to 6 heteroatoms and 1 to 30 carbon atoms, polyacrylate or polymethacrylate. A divalent group, or a direct bond, and n
Is an integer of 1 to 100. ] And a piperazine derivative represented by the formula (B)

[Chemical 5] [In the formula, R ³ is, independently of each other, a substituted or unsubstituted alkyl group having 1 to 18 carbon atoms, a substituted or unsubstituted aralkyl group having 7 to 21 carbon atoms, or a substituted or unsubstituted carbon number. 6 to 20 aryl groups, R ⁴
Are, independently of each other, a substituted or unsubstituted carbon number 1 to
18 alkylene groups, substituted or unsubstituted carbon number 6 to
20 arylene group, substituted or unsubstituted carbon number 7 to
21 aryl alkylene group, substituted or unsubstituted C 7-21 arylene alkylene group, dialkyl (poly) silylene group, diaryl (poly) silylene group,
A dialkylsilylene bis (alkylene) group or a direct bond, and Z ² is a divalent linking group, which is a disubstituted divalent silicon atom, a substituted or unsubstituted C 1 to C 1
18 alkylene groups, substituted or unsubstituted carbon number 6 to
20 arylene groups, 1 to 50 hetero atoms and 1 carbon atom
~ 100 heteroatom-containing organic groups, benzene polycarboxy groups, phosphoric acid groups, groups derived from polyacrylates or polymethacrylates, or showing direct bonds]
Obtained by an addition reaction with a compound represented by
Linear copolymer having two hydrosilyl groups at the end and formula (D) having at least 3 ethylenic double bonds

[Chemical 6] [In formula, R < ⁶ > shows a hydrogen atom, a substituted or unsubstituted C1-C18 alkyl group, or a substituted or unsubstituted C6-C20 aryl group each independently,
R ^7's are each independently a substituted or unsubstituted alkylene group having 1 to 18 carbon atoms, a substituted or unsubstituted arylene group having 6 to 20 carbon atoms, a substituted or unsubstituted arylalkylene group having 7 to 21 carbon atoms. Group, 1 to 6 heteroatoms
Represents a hetero atom-containing organic group having 1 to 30 carbon atoms or a direct bond, n ¹ is an integer of 3 or more, and Z
³ is a linking group having the same valence as n ^1, and is a carbon atom,
Alkanepolyyl group having 1 to 18 carbon atoms, 6 to 20 carbon atoms
A polyvalent aromatic carbocyclic group, an alkanepolyoxy group having 1 to 12 carbon atoms, a silicon atom, a mono-substituted trivalent silicon atom, an aliphatic group having 1 to 300 carbon atoms, a hetero atom having 1 to 50 carbon atoms, and a carbon atom having 1 carbon atom. To 100 heteroatom-containing organic groups, benzene polycarboxy groups, phosphoric acid groups, oxyphosphoric acid groups, groups derived from polyacrylates or polymethacrylates, or direct bonds, R ⁸ is, independently of one another, substituted or An unsubstituted alkyl group having 1 to 18 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms,
R ⁹ is independently of each other, a substituted or unsubstituted alkylene group having 1 to 18 carbon atoms, a substituted or unsubstituted arylene group having 6 to 20 carbon atoms, a substituted or unsubstituted arylalkylene group having 7 to 21 carbon atoms. Group, 1 to 6 heteroatoms
Represents a hetero atom-containing organic group having 1 to 30 carbon atoms, or a direct bond, n ² represents an integer of 2 to 30, a represents, independently of each other, an integer of 0 to 3, and Z ⁴ represents A linking group having the same valence as n ² , which is a carbon atom, an alkylene group having 1 to 18 carbon atoms, an alkynyl group having 1 to 18 carbon atoms, a polyvalent aromatic carbocyclic group having 6 to 20 carbon atoms, and carbon. Alkane polyoxy group having 1 to 12 carbon atoms, silicon atom, mono-substituted trivalent silicon atom, aliphatic group having 1 to 300 carbon atoms, and 1 to 5 hetero atoms
0 represents a hetero atom-containing organic group having 1 to 100 carbon atoms, a benzene polycarboxy group, a phosphoric acid group, an oxyphosphoric acid group, a group derived from polyacrylate or polymethacrylate, or a direct bond. ] It was found that at least a cross-linked polymer obtained by addition reaction of the compound represented by

When the pH of the activated carbon species is out of the range of 4 to 9, the polymer electrolyte polymerization reaction is hindered by the influence of hydroxyl groups, acid groups, basic groups and the like, which are often present on the surface of the activated carbon species. As in the invention, when the pH is in the range of 4 to 9, the polymerization reaction of the polymer electrolyte is not hindered.

The piperazine derivative represented by the formula (A) is less likely to be decomposed by an acid caused by an electrolyte or activated carbon species, and when an electric double layer capacitor is manufactured,
When a method of incorporating an electrode, a polymer electrolyte material and the like into a cell for a capacitor and polymerizing is used, the piperazine derivative captures a part of impurities such as an acid resulting from the electrolyte and activated carbon species, and thus the polymerization reaction is less likely to be hindered. Therefore,
Compared with known polymer electrolytes, it is possible to take a wider usable pH range of activated carbon species.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
The electric double layer capacitor according to the present invention has a structure in which polarizable electrodes face each other via a polymer electrolyte.

As the polarizable electrode relating to the electric double layer capacitor of the present invention, a sheet-shaped one obtained by kneading an activated carbon species such as carbon fiber, fibrous activated carbon or fine powder activated carbon and an organic binder is used. be able to. This polarizable electrode may be formed and integrated in a sheet shape on the metal current collector. As the organic binder, polyvinylidene fluoride, polytetrafluoroethylene, polyimide resin, polyamideimide resin, etc. can be used. Further, as the metal current collector, a foil such as aluminum or stainless steel, a net, or the like can be used.

The pH value of the activated carbon species related to the electric double layer capacitor of the present invention is measured by the method described in JIS-K-1474, and the value is in the range of 4-9.

As the polymer electrolyte relating to the electric double layer capacitor of the present invention, either an all-solid-state electrolyte containing no electrolytic solution or a gel electrolyte containing an electrolytic solution may be used.

The polymer electrolyte relating to the electric double layer capacitor of the present invention has a terminal hydrosilyl group obtained by the addition reaction of the piperazine derivative represented by the formula (A) and the compound represented by the formula (B). It contains at least a crosslinked polymer obtained by addition-reacting a linear copolymer having two and a compound represented by the formula (D) having at least 3 ethylenic double bonds.

In the piperazine derivative represented by the formula (A) relating to the electric double layer capacitor of the present invention, R ¹
Examples of the alkyl group having 1 to 18 carbon atoms represented by include a methyl group, an ethyl group, a propyl group, a butyl group, an octyl group, a dodecyl group, and the like, and having 6 to 2 carbon atoms.
Examples of the aryl group of 0 include a phenyl group, a toluyl group, a naphthyl group and the like. R ¹ is preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms, and most preferably a hydrogen atom or a methyl group.

In the formula (A), the alkylene group having 1 to 18 carbon atoms represented by R ² includes, for example, methylene group, ethylene group, propylene group, butylene group, octylene group, dodecylene group and the like. The saturated cycloalkylene group of the formulas 6 to 20 includes, for example, a cyclohexylene group, a cycloheptylene group, a cyclooctylene group and the like, and the unsaturated cycloalkylene group includes, for example, a cyclohexenylene group and a cycloheptenylene group. , A cyclooctenylene group, a cyclohexadienylene group, a cycloheptadienylene group and the like are included, and the arylene group having 6 to 20 carbon atoms includes, for example, a phenylene group, a naphthylene group and the like, and 7 to 7 carbon atoms. Examples of the arylalkylene group of 21 include a phenylmethylene group, a phenylethylene group, a phenylethylidene group, and the like. Murrell. The arylenealkylene group having 7 to 21 carbon atoms represented by R ² includes, for example,
A phenylene methylene group and the like are included, and the arylene bis (alkylene) group having 8 to 22 carbon atoms includes, for example, a xylylene group. The alkyl group of the dialkyl (poly) silylene group represented by R ² preferably has 1 to 1 carbon atoms.
6 has, for example, a methyl group, an ethyl group, a propyl group,
A butyl group and the like are included, and the aryl group of the diaryl (poly) silylene group preferably has 6 to 10 carbon atoms, and examples thereof include a phenyl group, a toluyl group, a naphthyl group and the like. Preferably, R ² is an alkylene group having 1 to 6 carbon atoms, particularly a methylene group, an arylene having 6 to 10 carbon atoms, especially a phenylene group, or 8 to 1 carbon atoms.
2 is an arylene bis (alkylene) group, especially a xylylene group.

In the formula (A), the heteroatom-containing organic group having 1 to 6 heteroatoms and 1 to 30 carbon atoms represented by R ² contains oxygen, sulfur or nitrogen atom as a heteroatom in the main chain. Which are heteroatoms,
Present between carbon atoms in ethers, thioethers and /
Alternatively, it may form a secondary amino group, be present on a carbon atom to form a carbonyl, thiocarbonyl and / or imino group, or a mixture thereof. Therefore, the heteroatom-containing organic group also includes a (poly) oxyalkylene group, a (poly) carbonate group, a (poly) ester group, and an amide group, but a polyacrylate containing a hetero atom only in a side chain. Groups such as and polymethacrylate are not included.

In the formula (A), the (poly) oxyalkylene group represented by R ² preferably has 1 to 1 carbon atoms.
Groups derived from polymers of alkylene oxides having 6, for example poly (oxymethylene), poly (oxyethylene), poly (oxypropylene), poly (oxybutylene), poly (oxypentylene), and those Copolymers of The (poly) carbonate group is a divalent group in which a glycol or polyglycol such as ethylene glycol or propylene glycol, or an arylene diol or polyarylene diol such as phenylene diol is linked via —O (CO) O—. , Glycol is preferably 1 to 12,
More preferably 2-8, most preferably 2-6 carbon atoms, the arylene diol is preferably 6-10,
More preferably it has 6 to 8, most preferably 6 carbon atoms.

In formula (A), the (poly) ester group represented by R ² is a dicarboxylic acid such as glycolic acid, adipic acid, phthalic acid or terephthalic acid, and a glycol or polycarboxylic acid such as ethylene glycol or propylene glycol. It is a divalent group obtained by dehydration condensation with glycol or an arylene diol such as phenylene diol or a polyarylene diol. As the glycol and the arylene diol in this case, the same ones as in the case of the (poly) carbonate group can be used.

In R ² of the formula (A), the number of hetero atoms is 1
The preferred molecular weight of the heteroatom-containing organic group having 1 to 6 carbon atoms and 1 to 30 carbon atoms, and the divalent group derived from polyacrylate and polymethacrylate is 60 to 30000.
It is 0, preferably 100 to 10,000.

When R ¹ and R ² in the formula (A) have a substituent, those substituents include halogen such as chlorine, fluorine and bromine, and a cyano group. Specific groups having a substituent include a trifluoropropyl group,
A halogenated alkyl group such as a chloropropyl group, and 2
Includes cyanoalkyl groups such as cyanoethyl groups. N in the formula (A) is preferably 1 to 70, particularly preferably 2 to 20.

Specific examples of the compound represented by the formula (A) relating to the electric double layer capacitor of the present invention include:

[0023]

[Chemical 7]

[0024]

[Chemical 8]

[0025]

[Chemical 9] Etc.

In the compound represented by the formula (B) relating to the electric double layer capacitor of the present invention, examples of the alkyl group having 1 to 18 carbon atoms and the aryl group having 6 to 20 carbon atoms represented by R ³ are as follows: It is the same as shown for R ^{1 in} (A). The aralkyl group having 7 to 21 carbon atoms represented by R ³ includes, for example, a benzyl group and a phenethyl group. Preferably, R ³ is an alkyl group having 1 to 6 carbon atoms, more preferably 1 to ³ carbon atoms, and most preferably a methyl group.

In the formula (B), R ⁴ represents an alkylene group having 1 to 18 carbon atoms, an arylene group having 6 to 20 carbon atoms, an arylalkylene group having 7 to 21 carbon atoms, and an arylene alkylene group having 7 to 21 carbon atoms. Examples of the dialkyl (poly) silylene group and the diaryl (poly) silylene group are the same as those shown for R ^{2 in the} formula (A). The alkyl group of the dialkylsilylenebis (alkylene) group represented by R ⁴ is an alkyl group having 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms, and the alkylene group is a methylene group, an ethylene group, a propylene group, Examples thereof include a butylene group, a hexylene group and an octylene group. Two
The two alkylene groups may be the same or different from each other. Preferred dialkylsilylene bis (alkylene) groups include dimethylsilylene (methylene) ethylene,
Dimethylsilylene (ethylene) ethylene and dimethylsilylene (ethylene) butylene are included. Preferably, R ⁴ has 1 to 6 carbon atoms, more preferably 1 to 6 carbon atoms.
3 alkylene groups, most preferably methylene groups, dimethylsilylene (ethylene) butylene, or direct bonds.

The substituent of the disubstituted divalent silicon atom represented by Z ^{2 in the} formula (B) includes an alkyl group having 1 to 18 carbon atoms or an aryl group having 6 to 20 carbon atoms, preferably carbon number. 1 to 6, more preferably an alkyl group having 1 to 3 carbon atoms, and most preferably a methyl group. Therefore, the preferred disubstituted divalent silicon atom is a dialkylsilylene group, most preferably a dimethylsilylene group. Examples of the alkylene group having 1 to 18 carbon atoms and the arylene group having 6 to 20 carbon atoms represented by Z ² are the same as those shown for R ^{2 in} formula (A). The definitions and examples of the heteroatom-containing organic group having 1 to 50 carbon atoms and 1 to 100 carbon atoms represented by Z ² are the same as those of the formula (A) except that the number of heteroatoms and the number of carbon atoms contained therein may be different. It is the same as the definition and examples of the hetero atom-containing organic group having 1 to 6 hetero atoms and 1 to 30 carbon atoms shown for R ² . Preferably, Z ² is a dimethylsilylene group,
An alkylene group having 1 to 12 carbon atoms, a phenylene group, 100
Poly (oxyethylene) having a molecular weight of ~ 2,000
Groups, polyoxyalkylene groups such as poly (oxypropylene) groups, and copolymers thereof, (poly) carbonate groups, and (poly) ester groups.

When R ³ , R ⁴ and Z ² in the formula (B) have a substituent, examples of the substituent are the same as those shown for R ¹ and R ² in the formula (A).

Specific examples of the compound represented by the formula (B) relating to the electric double layer capacitor of the present invention include:

[0031]

[Chemical 10]

[0032]

[Chemical 11]

And the like.

The linear copolymer having two terminal hydrosilyl groups, which is obtained by the addition reaction of the piperazine derivative represented by the formula (A) and the compound represented by the formula (B), has X moles. It is formed by an addition reaction between the piperazine derivative represented by the formula (A) and (X + 1) mol of the compound represented by the formula (B).

The addition reaction (hydrosilylation reaction) between the piperazine derivative represented by the formula (A) and the compound represented by the formula (B) is from room temperature to 150 ° C., preferably 40 to
It can be carried out at a temperature of 120 ° C. A catalyst is used for this hydrosilylation reaction. As the catalyst, compounds such as platinum, ruthenium, rhodium, palladium, osmium and iridium are known. Platinum compounds are particularly useful because they have high activity. Examples of platinum compounds include chloroplatinic acid, simple substance of platinum, alumina, silica,
Solid platinum supported on a carrier such as carbon black, platinum-vinyl siloxane complex, platinum-phosphine complex, platinum-phosphite complex, platinum alcoholate catalyst and the like can be used. During the hydrosilylation reaction, the platinum catalyst is added as platinum in an amount of about 0.0001 to 0.1% by mass.

The reaction solvent for the addition reaction between the piperazine derivative represented by the formula (A) and the compound represented by the formula (B) is a sulfur compound such as thiophene, diethyl sulfide, dimethylsulfoxide, sulfolane; acetonitrile, diethylamine. , Nitrogen compounds such as aniline; acetals; ketones such as cyclohexanone; esters; phenols; hydrocarbons such as toluene, xylene, hexane, and isoparaffins; halogenated hydrocarbons; dimethylpolysiloxane; propylene carbonate, ethylene carbonate, γ-butyrolactone, dimethyl Ester compounds having a carbonyl bond such as carbonate and diethyl carbonate; tetrahydrofuran, 2-methoxytetrahydrofuran, 1,3-dioxolane, 1,2-dimethoxyethane, 1,2-di Tokishietan, 1, 3-ether compounds such as dioxane; methanol, ethanol,
Alcohols such as 2-propanol and butanol can be used alone or in combination.

The molecular weight of the linear copolymer having two hydrosilyl groups at the terminal, which is obtained by the addition reaction of the piperazine derivative represented by the formula (A) and the compound represented by the formula (B), is 230. Or more, preferably 30
It is 0 to 30,000.

R ⁶ of the compound represented by the formula (D) relating to the electric double layer capacitor of the present invention has 1 carbon atom
Examples of the alkyl group having 18 to 18 and the aryl group having 6 to 20 carbons are the same as those shown for R ^{1 in the} formula (A).

R ⁷ of the compound represented by the formula (D) is an alkylene group having 1 to 18 carbon atoms and 6 to 20 carbon atoms.
Examples of the arylene group and the arylalkylene group having 7 to 21 carbon atoms are the same as those shown for R ^{2 in the} formula (A). In addition, the number of heteroatoms represented by R ⁷ is 1
Examples of the heteroatom-containing organic group having 1 to 6 carbon atoms and 1 to 30 carbon atoms include:
In addition to those shown for R ^{2 in} formula (A), alkyl-
Included are polyoxyalkylene-alkyl groups. The alkyl group includes an alkyl group having 1 to 6 carbon atoms such as a methyl group, an ethyl group, a propyl group, or a butyl group. Specifically, methyl-poly (oxyethylene) -methyl, methyl- Included are poly (oxypropylene) -methyl, methyl-poly (oxyethylene) -propyl, ethyl-poly (oxybutylene) -ethyl, ethyl-poly (oxypentylene) -propyl, and copolymers thereof.

Z of the compound represented by the formula (D)³Nitsu
The C 1-18 alkanepolyyl group has a methyl group.
Nyl group, ethynyl group, propynyl group, butynyl group, octyl group
Alkynyl groups such as tyl and dodecynyl
Or a 1,2,3-propanetriyl group or the like is included. Charcoal
An alkynyl group having a prime number of 1 to 12 is preferable, and a carbon number of 1 to 6
The alkynyl group of is more preferable. Z³Indicated by charcoal
The polyvalent aromatic carbocyclic group having a prime number of 6 to 20 includes benzenetriene
And an alkyl group and a naphthalenetriyl group. Z ³By
To an alkanepolyoxy group having 1 to 12 carbon atoms
Is a 1,2,3-propanetrioxy group, 1,2,3,
4-butanetetraoxy group, 1, 2, 3, 4, 5, 6-
Hexanehexaoxy etc. are included. Z³Indicated by
Mono-substituted trivalent silicon atoms include, for example, ≡Si-alkyl.
And the alkyl group has 1 to 6 carbon atoms,
More preferably, it is an alkyl group having 1 to 3 carbon atoms, and is most preferable.
Is a methyl group. Therefore, ≡Si-alkyl
The most preferable specific example is ≡Si—CH.₃To raise
You can

Regarding Z ³ of the compound represented by the formula (D), the heteroatom-containing organic group having 1 to 50 heteroatoms and 1 to 100 carbon atoms is a heteroatom in the main chain as a heteroatom. A group containing atoms, wherein these heteroatoms are present on carbon atoms even if they are present between carbon atoms to form ether, thioether and / or secondary amino groups. /
Alternatively, it may form an imino group or a mixture thereof. Therefore, in this hetero atom-containing organic group,
It also includes (poly) oxyalkylene groups, (poly) carbonate groups, (poly) ester groups, and amide groups, but does not include groups such as polyacrylates and polymethacrylates that contain heteroatoms only in the side chains. .

Regarding Z ³ of the compound represented by the formula (D), as the hetero atom-containing organic group having 1 to 50 hetero atoms and 1 to 100 carbon atoms, a methylene oxymethynyl group, a methylene oxyethynyl group and a methylene group can be used. C1-C6 alkylene such as oxypropynyl group, ethyleneoxypropynyl group, methyleneoxyethyleneoxymethynyl group, ethyleneoxyethyleneoxyethynyl group, propyleneoxyethyleneoxypropynyl group, phenylenebis (methyloxyethynyl) group Group, carbon number 6 to 1
A group in which an arylene group having 0 or an arylene dialkylene group having 8 to 22 carbon atoms is bonded to an alkynyl group having 1 to 6 carbon atoms by an ether bond; a trioxotriazine group, and a part of those oxygen atoms is sulfur and / or Included are those replaced with nitrogen atoms.

Regarding Z ³ of the compound represented by the formula (D), the benzenepolycarboxy group includes a group derived from benzenetricarboxylic acid and benzenetetracarboxylic acid. For Z ³ , examples of polyoxyalkylenes, (poly) carbonates and (poly) esters are similar to those given for Z ^{2 in} formula (B).
The preferred molecular weights of those obtained by adding polyacrylate and methacrylate are also the same as those shown for Z ^{2 in the} formula (B).

In the compound represented by the formula (D),
Preferably, R ⁶ is a hydrogen atom or a methyl group, and R ⁷
Methylene group, an ethylene group, a direct bond, -CH ₂ OCH
_{2 -, - CH 2 OCH 2} CH 2 -, or CH ₂ OCH
₂ CH ₂ OCH ₂ - and and, Z ³ is a carbon atom, Mechiniru group, an ethynyl group, a benzenetriyl group or a silicon atom, and n ¹ is an integer of 3-10.

In the compound represented by the formula (D),
Examples of R ⁸ are the same as those shown for R ⁶ , except that R ⁸ cannot be a hydrogen atom, and R ⁹ The example of is similar to that shown for R ⁷ . Examples of the alkylene group having 1 to 18 carbon atoms in Z ⁴ are the same as those shown for R ^{2 in} formula (A). Further, examples of the alkynyl group having 1 to 18 carbon atoms are the same as those shown in the description of the alkane poly-yl group having 1 to 18 carbon atoms Z ³ of formula (D). Examples of other groups of Z ⁴ are the same as those shown for Z ³ except that the valences may be different. In addition, preferable examples of R ⁸ , R ⁹ and Z ⁴ are:
R ⁶ , R ⁷ And Z ³ are the same as those described above.
Preferred a is an integer of 1 to 3, and preferred n ² is 2
It is an integer of 10, especially 2 to 6.

Specific examples of the compound represented by the formula (D) include:

[0047]

[Chemical 12]

[0048]

[Chemical 13]

[0049]

[Chemical 14]

[0050]

[Chemical 15]

[0051]

[Chemical 16]

[0052]

[Chemical 17]

[0053]

[Chemical 18]

[0054]

[Chemical 19]

And the like.

In the electric double layer capacitor of the present invention,
A linear copolymer having two hydrosilyl groups at the end, which is obtained by an addition reaction of a piperazine derivative represented by the formula (A) and a compound represented by the formula (B), and at least 3 ethylenic double bonds The crosslinked copolymer obtained by the addition reaction of the compound represented by formula (D) having a bond is formed by utilizing a hydrosilylation reaction.

In the electric double layer capacitor of the present invention,
A piperazine derivative represented by the formula (A), and a formula (B)
The compound represented by and the compound represented by the formula (D) can be simultaneously reacted to obtain a crosslinked polymer.

In the hydrosilylation reaction for forming a crosslinked polymer, the starting compounds can be mixed at room temperature or lower and then heated to accelerate the reaction. In this case, the heating temperature is 50 to 150 ° C, preferably 60 to 120 ° C. As the catalyst that can be used in the hydrosilylation reaction, the above-mentioned catalyst can be used.

In the electric double layer capacitor of the present invention, a composite type polymer electrolyte in which the polymer electrolyte is integrated with the electrically insulating porous thin film may be used. As the electrically insulating porous thin film, a porous film, a non-woven fabric or the like can be used. The porous film is, for example, a polyolefin film made of a thermoplastic resin such as polyolefin, polyester, polyvinyl chloride, polyvinyl alcohol, polyacrylonitrile, polyamide, or fluororesin by a uniaxial stretching method or a biaxial stretching method. Can be used.

In the electric double layer capacitor of the present invention,
When the polymer electrolyte is a gel electrolyte, an aprotic polar solvent with a high dielectric constant or a low viscosity, or an organic solvent that is electrochemically stable and dissolves an electrolyte salt is used as the medium of the electrolytic solution. To do. For example, propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, carbonates such as ethylmethyl carbonate, lactones such as γ-butyrolactone, amide solvent such as dimethylformamide, dimethylacetamide, sulfolane, acetonitrile,
Examples thereof include dimethyl sulfoxide, tetrahydrofuran, dimethoxyethane and the like. These electrolytes are
In the polymer electrolyte relating to the electric double layer capacitor of the present invention, it is present in an amount of 0 to 99% by mass.

Electricity relating to the electric double layer capacitor of the present invention
Degradation salts include metal cations, ammonium ions,
Selectable from amidinium ion and guanidinium ion
Exposed cations, chlorine ions, bromine ions, iodine ions
On, perchlorate ion, thiocyanate ion, tetraf
Luoroboronate ion, nitrate ion, AsF₆ ^-, P
F ₆ ^-, Stearyl sulfonate ion, octyl sulfone
Acid ion, dodecylbenzene sulfonate ion, naphthalate
Rene sulfonate ion, dodecylnaphthalene sulfonic acid
Ion, 7,7,8,8-tetracyano-p-quinodime
Tanion, X¹SO₃ ^-, [(X¹SO₂) (X²SO₂)
N]^-, [(X¹SO₂) (X²SO₂) (X³SO₂) C]^-
And [(X¹SO₂) (X²SO₂) YC]^-Chosen from
And an anion. However, X
¹, X², X³And Y are electron withdrawing groups. further,
Preferably X¹, X²And X³Each independently has a carbon number
1-6 perfluoroalkyl groups or perfluoro groups
Reel group, Y is nitro group, nitroso group, carbonyl group
Group, a carboxyl group, or a cyano group. X¹,
X²And X³Can be the same or different
Yes. These electrolytes are used in the electric double layer capacitor of the present invention.
In the polymer electrolyte concerned, 0.1-60 mass%,
It is preferably present in an amount of 1.0-40% by weight.

Further, polyalkylene oxide compounds such as tetraethylene glycol dimethyl ether and tetrapropylene glycol dimethyl ether, modified polyacrylates having polyalkylene oxide as a structural unit,
Ion conductive polymers such as polyacrylonitrile, polyvinylidene fluoride, and modified polyphosphazene having a structural unit of polyalkylene oxide can also be blended.

As a method for producing the electric double layer capacitor of the present invention, (a) after incorporating the polarizable electrode and the electrically insulating porous thin film into the capacitor cell, the raw material of the polymer electrolyte is injected,
Polymerization method (b) There is a method of polymerizing a polymer electrolyte in advance and incorporating it into a capacitor cell together with a polarizable electrode.

[0064]

EXAMPLES The present invention will be described in detail below with reference to examples.

Example 1 To the mixed solution shown in Table 1, 197.9 parts by weight of 1,2-dichloroethane dissolved in 78 parts by weight of acetonitrile was added.
It was added dropwise at 0 ° C. over 1 hour. The mixture was stirred at the same temperature for 6 hours, and then cooled to 50 ° C. Next, 76.5 parts by weight of allyl chloride dissolved in 78 parts by weight of acetonitrile was added dropwise to this reaction liquid over about 1 hour. After the dropping, the inorganic salt was filtered off from the reaction product obtained by stirring for 2 hours, and acetonitrile was distilled off. 870 parts by weight of toluene was added to the residue, and the mixture was stirred with heating for 1 hour. After filtering off the insoluble matter, 3000 parts by weight of purified water was added. After filtering with 300 parts by weight of diatomaceous earth (Celite 545), the mixture was separated into a toluene layer and an aqueous layer.

[0066]

[Table 1]

The product was extracted from the aqueous layer with 3 L of chloroform. After distilling off the solvent, the residue was dissolved in 2-propyl alcohol. This solution was subjected to silica gel (silica gel C-20 using 2-propyl alcohol as a developing solvent.
0, manufactured by Wako Pure Chemical Industries, Ltd.) was subjected to column chromatography treatment. The obtained separated product was recrystallized with methyl isobutyl ketone to obtain a compound (A-3).

The raw materials shown in Table 2 were mixed and reacted at 90 ° C. for 6 hours in a nitrogen atmosphere, and then toluene was removed to obtain a linear block copolymer (C-3 having a hydrosilyl group at both ends). ) Was synthesized.

[0069]

[Table 2]

[0070]

[Chemical 20]

On the other hand, pH 6.5 and specific surface area 2000
m ² / g, 80 g of fine powder activated carbon having an average particle size of 8 μm, and 20 g of polytetrafluoroethylene powder were kneaded, and then applied on an aluminum foil in a heated state, and then cooled,
It was used as a capacitor electrode a.

When the capacitor electrode a, a commercially available capacitor separator, and the polymer electrolyte reaction solution I shown in Table 3 were assembled in a capacitor cell and heated to 80 ° C., the reaction solution I was polymerized after 30 minutes. It was confirmed that it was a gel electrolyte.

[0073]

[Table 3]

Example 2 pH 5.3, specific surface area 2000 m ² / g, average particle size 8
80 g of micronized activated carbon powder and 20 g of polytetrafluoroethylene powder were kneaded, and then applied on an aluminum foil in a heated state and then cooled to obtain a capacitor electrode b.

When the capacitor electrode b, a commercially available capacitor separator, and the polymer electrolyte reaction solution I shown in Table 3 were assembled in a capacitor cell and heated to 80 ° C., the reaction solution I was polymerized after 30 minutes. It was confirmed that it was a gel electrolyte.

Example 3 pH 4.3, specific surface area 2000 m ² / g, average particle size 8
After 80 g of fine powder activated carbon of 20 μm and 20 g of polytetrafluoroethylene powder were kneaded, they were coated on an aluminum foil in a heated state and then cooled to obtain a capacitor electrode c.

When the capacitor electrode c, a commercially available capacitor separator, and the polymer electrolyte reaction solution I shown in Table 3 were assembled in a capacitor cell and heated to 80 ° C., the reaction solution I was polymerized after 30 minutes. It was confirmed that it was a gel electrolyte.

Example 4 pH 7.9, specific surface area 2000 m ² / g, average particle size 8
After 80 g of fine powder activated carbon of 20 μm and 20 g of polytetrafluoroethylene powder were kneaded, they were applied onto an aluminum foil in a heated state and then cooled to obtain a capacitor electrode d.

When the capacitor electrode d, a commercially available capacitor separator, and the polymer electrolyte reaction solution I shown in Table 3 were assembled in a capacitor cell and heated to 80 ° C., the reaction solution I was polymerized after 30 minutes. It was confirmed that it was a gel electrolyte.

Example 5 pH 8.8, specific surface area 2000 m ² / g, average particle size 8
80 g of fine powder activated carbon having a particle size of 80 μm and 20 g of polytetrafluoroethylene powder were kneaded, and then coated on an aluminum foil in a heated state and then cooled to obtain a capacitor electrode e.

When the capacitor electrode e, a commercially available capacitor separator, and the polymer electrolyte reaction solution I shown in Table 3 were assembled in a capacitor cell and heated to 80 ° C., the reaction solution I was polymerized after 30 minutes. It was confirmed that it was a gel electrolyte.

Comparative Example 1 80 g of finely powdered activated carbon having a pH of 9.5, a specific surface area of 2000 m ² / g and an average particle size of 8 μm, and 20 g of polytetrafluoroethylene powder were kneaded and then applied on an aluminum foil in a heated state. Then, it cooled and it was set as the electrode f for capacitors.

A capacitor electrode f, a commercially available capacitor separator, and the polymer electrolyte reaction solution I shown in Table 3 used in Example 1 were incorporated into a capacitor cell,
When heated to 80 ° C., the reaction solution I remained in a fluid state.

Comparative Example 2 80 g of finely powdered activated carbon having a pH of 3.5, a specific surface area of 2000 m ² / g and an average particle size of 8 μm and 20 g of polytetrafluoroethylene powder were kneaded and then applied on an aluminum foil in a heated state, Then, it cooled and it was set as the electrode g for capacitors.

A capacitor electrode g, a commercially available capacitor separator, and the polymer electrolyte reaction solution I shown in Table 3 used in Example 1 were incorporated into a capacitor cell,
When heated to 80 ° C., the reaction solution I remained in a fluid state.

Comparative Example 3 80 g of finely powdered activated carbon having a pH of 10.1, a specific surface area of 2000 m ² / g and an average particle size of 8 μm, and 20 g of polytetrafluoroethylene powder were kneaded and then applied on an aluminum foil in a heated state, Then, it cooled and it was set as the electrode h for capacitors.

A capacitor electrode h, a commercially available capacitor separator, and the polymer electrolyte reaction solution I shown in Table 3 used in Example 1 were incorporated into a capacitor cell,
When heated to 80 ° C., the reaction solution I remained in a fluid state.

Comparative Example 4 80 g of finely powdered activated carbon having a pH of 3.0, a specific surface area of 2000 m ² / g and an average particle size of 8 μm, and 20 g of polytetrafluoroethylene powder were kneaded and then applied on an aluminum foil in a heated state, Then, it cooled and it was set as the electrode i for capacitors.

A capacitor electrode i, a commercially available capacitor separator, and the polymer electrolyte reaction solution I shown in Table 3 used in Example 1 were incorporated into a capacitor cell,
When heated to 80 ° C., the reaction solution I remained in a fluid state.

Example 6 The polymer electrolyte reaction solution I shown in Table 3 was uniformly mixed. This reaction liquid I was cast on a polytetrafluoroethylene sheet, kept at 90 ° C. for 2 hours, cooled to room temperature, and then peeled off to prepare a polymer electrolyte alone membrane.

An electric double layer capacitor was manufactured by incorporating the capacitor electrode a and the above polymer electrolyte single film into a capacitor cell. The electric double layer capacitor was subjected to a continuous charge / discharge test of charging to 2.5V and then discharging to 0V for 300 cycles. When the electric double layer capacitor was disassembled after the test, no change was visually observed in the polymer electrolyte single film.

Example 7 An electric double layer capacitor was manufactured by incorporating the capacitor electrode c and the polymer electrolyte single membrane prepared in Example 6 into a capacitor cell. The electric double layer capacitor was subjected to a continuous charge / discharge test of charging to 2.5V and then discharging to 0V for 300 cycles. When the electric double layer capacitor was disassembled after the test, no change was visually observed in the polymer electrolyte single film.

Example 8 An electric double layer capacitor was manufactured by incorporating the capacitor electrode e and the polymer electrolyte single membrane prepared in Example 6 into a capacitor cell. The electric double layer capacitor was subjected to a continuous charge / discharge test of charging to 2.5V and then discharging to 0V for 300 cycles. When the electric double layer capacitor was disassembled after the test, no change was visually observed in the polymer electrolyte single film.

Comparative Example 5 An electric double layer capacitor was manufactured by incorporating the capacitor electrode f and the polymer electrolyte single film prepared in Example 6 into a capacitor cell. The electric double layer capacitor was subjected to a continuous charge / discharge test of charging to 2.5V and then discharging to 0V for 300 cycles. When the electric double layer capacitor after the test was disassembled, the polymer electrolyte single film was decomposed to be a liquid substance.

Comparative Example 6 An electric double layer capacitor was manufactured by incorporating the capacitor electrode g and the polymer electrolyte alone membrane prepared in Example 6 into a capacitor cell. The electric double layer capacitor was subjected to a continuous charge / discharge test of charging to 2.5V and then discharging to 0V for 300 cycles. When the electric double layer capacitor after the test was disassembled, the polymer electrolyte single film was decomposed to be a liquid substance.

Example 9 The polymer electrolyte reaction solution I shown in Table 3 was uniformly mixed. A polypropylene type microporous membrane (basis weight 15 g / m ² , thickness 50 μm, porosity 67%) was impregnated and squeezed, held at 90 ° C. for 2 hours, and then cooled to room temperature to prepare a composite polymer electrolyte. .

An electric double layer capacitor was manufactured by incorporating the capacitor electrode a and the composite polymer electrolyte described above into a capacitor cell. The electric double layer capacitor was subjected to a continuous charge / discharge test of charging to 2.5V and then discharging to 0V for 300 cycles. When the electric double layer capacitor was disassembled after the test, no change was visually observed in the polymer electrolyte single film.

Example 10 An electric double layer capacitor was manufactured by incorporating the capacitor electrode c and the composite polymer electrolyte prepared in Example 9 into a capacitor cell. The electric double layer capacitor was subjected to a continuous charge / discharge test of charging to 2.5V and then discharging to 0V for 300 cycles. When the electric double layer capacitor was disassembled after the test, no change was visually observed in the polymer electrolyte single film.

Example 11 An electric double layer capacitor was manufactured by incorporating the capacitor electrode e and the composite polymer electrolyte prepared in Example 9 into a capacitor cell. The electric double layer capacitor was subjected to a continuous charge / discharge test of charging to 2.5V and then discharging to 0V for 300 cycles. When the electric double layer capacitor was disassembled after the test, no change was visually observed in the polymer electrolyte single film.

Comparative Example 7 An electric double layer capacitor was manufactured by incorporating the capacitor electrode f and the composite polymer electrolyte prepared in Example 9 into a capacitor cell. The electric double layer capacitor was subjected to a continuous charge / discharge test of charging to 2.5V and then discharging to 0V for 300 cycles. When the electric double layer capacitor after the test was disassembled, the polymer electrolyte single film was in a liquid state.

Comparative Example 8 An electric double layer capacitor was manufactured by incorporating the capacitor electrode g and the composite polymer electrolyte prepared in Example 9 into a capacitor cell. The electric double layer capacitor was subjected to a continuous charge / discharge test of charging to 2.5V and then discharging to 0V for 300 cycles. When the electric double layer capacitor after the test was disassembled, the polymer electrolyte single film was in a liquid state.

[0102]

As described above, in the electric double layer capacitor of the present invention, p of activated carbon species contained in the polarizable electrode is used.
An excellent effect that a stable electric double layer capacitor can be obtained by setting H to an appropriate value and using a polymer electrolyte in which polymerization is not hindered by impurities and which is hardly decomposed is obtained.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Koshiro Ikegami             Mitsubishi 3-4-2 Marunouchi, Chiyoda-ku, Tokyo             Paper Manufacturing Co., Ltd. (72) Inventor Kazuyo Takaoka             Mitsubishi 3-4-2 Marunouchi, Chiyoda-ku, Tokyo             Paper Manufacturing Co., Ltd. (72) Inventor Kenichi Hino             4-173-2- Nogemachi, Naka-ku, Yokohama-shi, Kanagawa             609 (72) Inventor Naoki Suzuki             4-11-10-302 Minamikasai, Edogawa-ku, Tokyo (72) Inventor Kazuhiro Nishijima             1-20-11-201 Nakazato, Minami-ku, Yokohama-shi, Kanagawa (72) Inventor Kazuyuki Isobe             2-12-5 Kofudai, Fujishiro-cho, Kitasoma-gun, Ibaraki

Claims (2)

[Claims] 1. In an electric double layer capacitor comprising polarizable electrodes facing each other through a polymer electrolyte, the pH of the activated carbon species is in the range of 4 to 9, and the polymer electrolyte is of the formula (A ) [Chemical 1] [In the formula, R ^1, independently of one another, a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 18 carbon atoms or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms,, R ² is , Each independently, a substituted or unsubstituted alkylene group having 1 to 18 carbon atoms, a substituted or unsubstituted saturated or unsaturated cycloalkylene group having 6 to 20 carbon atoms, a substituted or unsubstituted 6 to 20 carbon atoms Arylene group, substituted or unsubstituted arylalkylene group having 7 to 21 carbon atoms, substituted or unsubstituted arylenealkylene group having 7 to 21 carbon atoms, substituted or unsubstituted 8 to 22 carbon atoms
Derived from an arylene bis (alkylene) group, a dialkyl (poly) silylene group, a diaryl (poly) silylene group, a heteroatom-containing organic group having 1 to 6 heteroatoms and 1 to 30 carbon atoms, polyacrylate or polymethacrylate. A divalent group, or a direct bond, and n
Is an integer of 1 to 100. ] And a piperazine derivative represented by the formula (B): [In the formula, R ³ is, independently of each other, a substituted or unsubstituted alkyl group having 1 to 18 carbon atoms, a substituted or unsubstituted aralkyl group having 7 to 21 carbon atoms, or a substituted or unsubstituted carbon number. 6-20 aryl group is shown, R ⁴ is, independently of each other, a substituted or unsubstituted alkylene group having 1 to 18 carbon atoms, a substituted or unsubstituted arylene group having 6 to 20 carbon atoms, substituted or unsubstituted An arylalkylene group having 7 to 21 carbon atoms, a substituted or unsubstituted arylenealkylene group having 7 to 21 carbon atoms, a dialkyl (poly) silylene group, a diaryl (poly) silylene group, a dialkylsilylenebis (alkylene) group, or directly Represents a bond, and Z ² is a divalent linking group, which is a disubstituted divalent silicon atom, a substituted or unsubstituted alkylene group having 1 to 18 carbon atoms, Derived from a substituted or unsubstituted arylene group having 6 to 20 carbon atoms, a hetero atom-containing organic group having 1 to 50 carbon atoms and 1 to 100 carbon atoms, benzene polycarboxy group, phosphoric acid group, polyacrylate or polymethacrylate. Or a linear copolymer having two hydrosilyl groups at the terminal, which is obtained by an addition reaction with a compound represented by the formula (D) or a compound (D) having at least 3 ethylenic double bonds. ) [Chemical 3] [In formula, R < ⁶ > shows a hydrogen atom, a substituted or unsubstituted C1-C18 alkyl group, or a substituted or unsubstituted C6-C20 aryl group each independently,
R ^7's are each independently a substituted or unsubstituted alkylene group having 1 to 18 carbon atoms, a substituted or unsubstituted arylene group having 6 to 20 carbon atoms, a substituted or unsubstituted arylalkylene group having 7 to 21 carbon atoms. Group, 1 to 6 heteroatoms
Represents a hetero atom-containing organic group having 1 to 30 carbon atoms or a direct bond, n ¹ is an integer of 3 or more, and Z
³ is a linking group having the same valence as n ^1, and is a carbon atom,
Alkanepolyyl group having 1 to 18 carbon atoms, 6 to 20 carbon atoms
A polyvalent aromatic carbocyclic group, an alkanepolyoxy group having 1 to 12 carbon atoms, a silicon atom, a mono-substituted trivalent silicon atom, an aliphatic group having 1 to 300 carbon atoms, a hetero atom having 1 to 50 carbon atoms, and a carbon atom having 1 carbon atom. To 100 heteroatom-containing organic groups, benzene polycarboxy groups, phosphoric acid groups, oxyphosphoric acid groups, groups derived from polyacrylates or polymethacrylates, or direct bonds, R ⁸ is, independently of one another, substituted or An unsubstituted alkyl group having 1 to 18 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, R ^9's each independently represent a substituted or unsubstituted alkylene having 1 to 18 carbon atoms; Group, substituted or unsubstituted arylene group having 6 to 20 carbon atoms, substituted or unsubstituted arylalkylene group having 7 to 21 carbon atoms, 1 to 6 hetero atoms
In, represents a hetero atom-containing organic group having 1 to 30 carbon atoms, or a direct bond, n ² represents an integer of 2 to 30, a represents an integer of 0 to 3 independently of each other, and Z ⁴ represents a linking group having the same valence as n ² and having a carbon atom,
C1-C18 alkylene group, C1-C18 alkynyl group, C6-C20 polyvalent aromatic carbocyclic group, C1-C12 alkane polyoxy group, silicon atom, monovalent trivalent group Silicon atom, aliphatic group having 1 to 300 carbon atoms, organic group containing hetero atom having 1 to 50 carbon atoms and 1 to 100 carbon atoms, benzene polycarboxy group, phosphoric acid group, oxyphosphoric acid group, polyacrylate or polymethacrylate. Represents a group derived from or a direct bond. ] The electric double layer capacitor containing at least the crosslinked polymer obtained by carrying out the addition reaction of the compound represented by this. 2. The electric double layer capacitor according to claim 1, wherein the polymer electrolyte is a composite type polymer electrolyte in which an electrically insulating porous thin film is integrated.