JP7420629B2 - Polyelectrolyte - Google Patents

Description

The present invention relates to a polymer electrolyte, a polymer electrolyte solution, an electrode catalyst ink, an electrode catalyst layer, a membrane electrode assembly, a fuel cell, and a method for producing a polymer electrolyte.

A membrane electrode assembly (MEA) that constitutes a polymer electrolyte fuel cell is provided with an electrode catalyst layer formed from a catalyst such as platinum and a polymer electrolyte. Since catalysts such as platinum are expensive, there is a need to reduce the amount of catalyst used, but reducing the amount of catalyst used tends to reduce battery performance. In order to avoid this disadvantage, attempts have been made to improve the oxygen permeability of the polymer electrolyte that forms the electrode catalyst layer to distribute oxygen throughout the electrode.

Patent Document 1 describes a polymer electrolyte that has high oxygen permeability and is suitable as a cathode side catalyst layer polymer electrolyte, and uses a repeating unit based on a fluorine-containing monomer that provides a polymer having an aliphatic ring structure in the main chain through radical polymerization. , a repeating unit based on a fluorinated sulfonic acid-containing monomer.

Japanese Patent Application Publication No. 2002-260705

However, since the polymer electrolyte disclosed in Patent Document 1 is not a microporous polymer, the power generation performance is insufficient under both low and high humidification conditions that are close to the actual operating environment of fuel cells. Therefore, there was room for improvement.

In view of the above-mentioned current situation, the present invention aims to provide a polymer electrolyte that can exhibit high power generation performance under both low humidification and high humidification conditions.

That is, the present invention is as follows.

・Aspect 1
A polymer electrolyte characterized by being a fluorine-containing microporous polymer having a proton-conducting group.

・Aspect 2
The polymer electrolyte according to aspect 1, wherein the proton conductive group is at least one selected from the group consisting of a sulfonic acid group and a phosphoric acid group.

式中、＊は結合手を表す。 ・Aspect 3
The polymer electrolyte according to aspect 2, wherein the sulfonic acid group includes a structure represented by the following formula (1).

In the formula, * represents a bond.

式中、＊は結合手を表す。 ・Aspect 4
The polymer electrolyte according to aspect 2 or 3, wherein the phosphoric acid group includes a structure represented by the following formula (2).

In the formula, * represents a bond.

・Aspect 5
The polymer electrolyte according to any one of aspects 1 to 4, wherein at least some of the repeating units of the fluorine-containing microporous polymer contain a 1,4-dioxin structure.

式中、
Ａｒ^１は、下記で表されるいずれか１つの構造を表し；

Ａｒ^２は、下記で表されるいずれか１つの構造を表し；

Ｒ^１は、それぞれ独立に、水素、ハロゲン基、シアノ基、ニトリル基、ニトロ基、ヒドロキシ基、置換もしくは非置換のアルキル基、置換もしくは非置換のシクロアルキル基、置換もしくは非置換のアルコキシ基、置換もしくは非置換のアリール基を表し；
ｍは０または１であり；
ｘは０＜ｘ≦６であり、ｙは０≦ｙ＜６であり、ｘ＋ｙ≦６であり；
Ａは、下記のいずれかの構造を表し；

Ｚは、Ｈ、Ｃｌ、Ｆ、又は炭素数１～３のパーフルオロアルキル基を表し；
ｐは０または１を表し、ｑは０～２の整数を表し、ｒは０～１２の整数を表し、ただし、ｑ及びｒは同時に０にならず；
ｓは０または１を表し、ｔは０または１を表し；
Ｙは、Ｆ、又はエーテル結合性酸素原子を有してもよい炭素数１～６のパーフルオロアルキル基を表し；
Ｒ_ｆは、それぞれ独立にエーテル結合性酸素原子を含む炭素数１～１０のフッ素化炭化水素基を表し；
＊は結合手を表す。 ・Aspect 6
The polymer electrolyte according to any one of aspects 1 to 5, wherein the fluorine-containing microporous polymer contains a repeating unit represented by the following formula (3).

During the ceremony,
Ar ¹ represents any one structure represented below;

Ar ² represents any one structure represented below;

R ¹ is each independently hydrogen, a halogen group, a cyano group, a nitrile group, a nitro group, a hydroxy group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted alkoxy group, represents a substituted or unsubstituted aryl group;
m is 0 or 1;
x is 0<x≦6, y is 0≦y<6, and x+y≦6;
A represents any of the following structures;

Z represents H, Cl, F, or a perfluoroalkyl group having 1 to 3 carbon atoms;
p represents 0 or 1, q represents an integer from 0 to 2, r represents an integer from 0 to 12, provided that q and r are not 0 at the same time;
s represents 0 or 1, t represents 0 or 1;
Y represents F or a perfluoroalkyl group having 1 to 6 carbon atoms which may have an ether-bonding oxygen atom;
R _f each independently represents a fluorinated hydrocarbon group having 1 to 10 carbon atoms containing an ether-bonding oxygen atom;
* represents a bond.

式中、
ｘは０＜ｘ≦６であり、ｙは０≦ｙ＜６であり、ｘ＋ｙ≦６である。 ・Aspect 7
The polymer electrolyte according to aspect 6, wherein the Ar ² has a structure represented by any one of the following formulas (4) to (8).

During the ceremony,
x is 0<x≦6, y is 0≦y<6, and x+y≦6.

・Aspect 8
The polymer electrolyte according to any one of aspects 1 to 7, which has a specific surface area of 250 to 6000 m ² /g as determined by the BET method.

・Aspect 9
A polymer electrolyte solution comprising the fluorine-containing microporous polymer electrolyte according to any one of aspects 1 to 8 and at least one selected from the group consisting of water and an organic solvent.

・Aspect 10
An electrode catalyst ink comprising the polymer electrolyte solution according to aspect 9 and a catalyst.

・Aspect 11
An electrocatalyst layer comprising the electrocatalyst ink according to aspect 10.

・Aspect 12
A membrane electrode assembly comprising the electrode catalyst layer according to aspect 11 and an electrolyte membrane.

・Aspect 13
A fuel cell comprising the membrane electrode assembly according to aspect 12.

・Aspect 14
(i) SO ₃ X group (wherein, X is an alkali metal , an alkaline earth metal, or NR ¹ R ² R ³ R ⁴ ; R ¹ , R ² , R ³ , and R ⁴ are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms. ) using a compound having SO ₃ X groups to obtain a fluorine-containing microporous polymer having SO ₃ X groups;
(ii) converting the SO ₃ X group of the fluorine-containing microporous polymer having the SO ₃ X group into a sulfonic acid group;
A method for producing a fluorine-containing microporous polymer electrolyte having a sulfonic acid group, the method comprising:

・Aspect 15
The step (i) is
(iii) An OW group (in the formula, W is hydrogen, an alkali metal, or an alkaline earth metal) is introduced into the fluorine-containing microporous polymer (P1) to create a fluorine-containing microporous polymer having an OW group. obtaining a porous polymer;
(iv) reacting the fluorine-containing microporous polymer having the OW group with the compound having the SO ₃ X group to obtain the fluorine-containing microporous polymer having the SO ₃ X group;
The method for producing a polymer electrolyte according to aspect 14, comprising:

・Aspect 16
The method for producing a polymer electrolyte according to aspect 14 or 15, wherein the step (ii) includes (v) ion-exchanging X of the SO ₃ X group to hydrogen.

式中、
Ｚは、Ｈ、Ｃｌ、Ｆ、又は炭素数１～３のパーフルオロアルキル基を表し；
ｑは０～２の整数、ｒは０～１２の整数を表し、ただし、ｑ及びｒは同時に０にならず；
ｔは０または１を表し；
Ｙは、Ｆ、又はエーテル結合性酸素原子を有してもよい炭素数１～６のパーフルオロアルキル基を表し；
Ｒ_ｆは、それぞれ独立にエーテル結合性酸素原子を含む炭素数１～１０のフッ素化炭化水素基を表し；
Ｘは、アルカリ金属、アルカリ土類金属、又はＮＲ^１Ｒ^２Ｒ^３Ｒ^４であり；
Ｒ^１、Ｒ^２、Ｒ^３、及びＲ^４は、それぞれ独立して、水素、又は炭素数１～４のアルキル基である。 ・Aspect 17
The method for producing a polymer electrolyte according to any one of aspects 14 to 16, wherein the compound having an SO ₃ X group has a structure represented by the following formula (9) or (10).

During the ceremony,
Z represents H, Cl, F, or a perfluoroalkyl group having 1 to 3 carbon atoms;
q represents an integer from 0 to 2, r represents an integer from 0 to 12, provided that q and r cannot be 0 at the same time;
t represents 0 or 1;
Y represents F or a perfluoroalkyl group having 1 to 6 carbon atoms which may have an ether-bonding oxygen atom;
R _f each independently represents a fluorinated hydrocarbon group having 1 to 10 carbon atoms containing an ether-bonding oxygen atom;
X is an alkali metal, an alkaline earth metal, or NR ¹ R ² R ³ R ⁴ ;
R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms.

式中、
Ｘは、アルカリ金属、アルカリ土類金属、又はＮＲ^１Ｒ^２Ｒ^３Ｒ^４であり；
Ｒ^１、Ｒ^２、Ｒ^３、及びＲ^４は、それぞれ独立して、水素、又は炭素数１～４のアルキル基である。 ・Aspect 18
The method for producing a polymer electrolyte according to any one of aspects 14 to 17, wherein the compound having an SO ₃ X group has a structure represented by the following formula (11).

During the ceremony,
X is an alkali metal, an alkaline earth metal, or NR ¹ R ² R ³ R ⁴ ;
R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms.

・Aspect 19
(a) An aromatic group, four or more halogen atoms bonded to the carbon atoms of the aromatic group, and an SO ₃ X group (X is an alkali metal, an alkaline earth metal, or NR ¹ R ² R ³ R ⁴ , and R ¹ , R ² , R ³ , and R ⁴ are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms) and one or more fluorine atoms. a step of preparing a group monomer (M1), an aromatic monomer (M2) having an aromatic group and four or more hydroxyl groups bonded to a carbon atom of the aromatic group;
(b) Condensation polymerization of the halogen atom of the aromatic monomer (M1) and the hydroxyl group of the aromatic monomer (M2) in the presence of a catalyst to obtain a fluorine-containing microporous polymer having an SO ₃ X group process and
(c) converting the SO ₃ X group of the fluorine-containing microporous polymer having the SO ₃ X group into a sulfonic acid group;
A method for producing a fluorine-containing microporous polymer electrolyte having a sulfonic acid group, the method comprising:

・Aspect 20
The method for producing a polymer electrolyte according to aspect 19, wherein the step (c) includes (d) ion-exchanging X of the SO ₃ X group to hydrogen.

・Aspect 21
The method for producing a polymer electrolyte according to aspect 19 or 20, wherein the halogen atom of the aromatic monomer (M1) is a fluorine atom.

式中、
Ｒ^１は、それぞれ独立に、水素、ハロゲン基、シアノ基、ニトリル基、ニトロ基、ヒドロキシ基、置換もしくは非置換のアルキル基、置換もしくは非置換のシクロアルキル基、置換もしくは非置換のアルコキシ基、置換もしくは非置換のアリール基を表し；
ｍは０または１であり；
Ｂは、下記のいずれかの構造を表し；

Ｚは、Ｈ、Ｃｌ、Ｆ、又は炭素数１～３のパーフルオロアルキル基を表し；
ｐは０または１を表し、ｑは０～２の整数を表し、ｒは０～１２の整数を表し、ただし、ｑ及びｒは同時に０にならず；
ｓは０または１を表し、ｔは０または１を表し；
Ｙは、Ｆ、又はエーテル結合性酸素原子を有してもよい炭素数１～６のパーフルオロアルキル基を表し；
Ｒ_ｆは、それぞれ独立にエーテル結合性酸素原子を含む炭素数１～１０のフッ素化炭化水素基を表し；
Ｘは、アルカリ金属、アルカリ土類金属、又はＮＲ^１Ｒ^２Ｒ^３Ｒ^４であり；
Ｒ^１、Ｒ^２、Ｒ^３、及びＲ^４は、それぞれ独立して、水素、又は炭素数１～４のアルキル基であり；
＊は結合手を表す。 ・Aspect 22
The method for producing a polymer electrolyte according to aspects 19 to 21, wherein the aromatic monomer (M1) has any one structure represented by the following (12).

During the ceremony,
R ¹ is each independently hydrogen, a halogen group, a cyano group, a nitrile group, a nitro group, a hydroxy group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted alkoxy group, represents a substituted or unsubstituted aryl group;
m is 0 or 1;
B represents any of the following structures;

Z represents H, Cl, F, or a perfluoroalkyl group having 1 to 3 carbon atoms;
p represents 0 or 1, q represents an integer from 0 to 2, r represents an integer from 0 to 12, provided that q and r are not 0 at the same time;
s represents 0 or 1, t represents 0 or 1;
Y represents F or a perfluoroalkyl group having 1 to 6 carbon atoms which may have an ether-bonding oxygen atom;
R _f each independently represents a fluorinated hydrocarbon group having 1 to 10 carbon atoms containing an ether-bonding oxygen atom;
X is an alkali metal, an alkaline earth metal, or NR ¹ R ² R ³ R ⁴ ;
R ¹ , R ² , R ³ , and R ⁴ are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms;
* represents a bond.

式中、
Ｘは、アルカリ金属、アルカリ土類金属、又はＮＲ^１Ｒ^２Ｒ^３Ｒ^４であり；
Ｒ^１、Ｒ^２、Ｒ^３、及びＲ^４は、それぞれ独立して、水素、又は炭素数１～４のアルキル基である。 ・Aspect 23
The method for producing a polymer electrolyte according to aspects 19 to 22, wherein the aromatic monomer (M1) has any one structure represented by the following (13).

During the ceremony,
X is an alkali metal, an alkaline earth metal, or NR ¹ R ² R ³ R ⁴ ;
R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms.

・Aspect 24
The method for producing a polymer electrolyte according to aspects 19 to 23, wherein the aromatic monomer (M2) has any one structure represented by the following (14).

The fluorine-containing microporous polymer electrolyte of the present invention can exhibit high power generation performance under both low humidification and high humidification conditions.

Hereinafter, a mode for carrying out the present invention (hereinafter referred to as "this embodiment") will be described in detail. Note that the present invention is not limited to the following embodiments, and can be implemented with various modifications within the scope of the gist.

In the manufacturing method described herein, words such as (i), (ii), and (iii), and (a), (b), and (c) are used to distinguish a step in the manufacturing method from other steps. This is a convenient term used only to describe the process and does not indicate the order of the process.

In this disclosure, numerical ranges are intended to include the lower and upper limits of that range, unless stated otherwise. For example, 250 to 6,000 ^{m 2} /g means 250 m ² /g or more and 6,000 m ² /g or less.

・Fluorine-containing microporous polymer electrolyte The polymer electrolyte of this embodiment is a fluorine-containing microporous polymer having a proton-conducting group, which increases the voids in the polymer electrolyte and exhibits high oxygen permeability. However, high power generation performance can be achieved under both low and high humidification conditions. Here, high humidification refers to a relative humidity of 60% RH or more, and low humidification refers to a relative humidity of 30% RH or less. Further, the electrode catalyst layer containing the polymer electrolyte has no cracks on the surface and can exhibit high chemical durability during operation of the fuel cell.

In this specification, microporous polymer refers to PIM (polymers of intrinsic microporosity). PIM is a type of microporous polymer and has high gas permeability. The inclusion of fluorine atoms in the microporous polymer improves the hydrophobicity and durability of the polymer electrolyte, contributing to high battery performance.

Examples of the proton conductive group include a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, and a sulfonamide group. The proton conductive group is preferably at least one selected from the group consisting of sulfonic acid groups and phosphoric acid groups. It may have either a sulfonic acid group or a phosphoric acid group, or it may have both. By having sulfonic acid groups, the polymer electrolyte of the present invention exhibits high proton conductivity under a wide range of humidified conditions. By having a phosphoric acid group, the polymer electrolyte of the present invention exhibits high proton conductivity even under low to no humidification conditions.

In one embodiment, high humidification conditions are 60-100% RH. In one embodiment, low humidification conditions are 0-30% RH.

＊は結合手を表す。 From the viewpoint of proton conductivity, the sulfonic acid group preferably includes a structure represented by the following formula (1), which is a strong acid. When the hydrocarbon adjacent to the sulfonic acid group is fluorine-containing, the acidity of the sulfonic acid group increases, proton conductivity improves, and contributes to high power generation performance.

* represents a bond.

＊は結合手を表す。 From the viewpoint of ease of synthesis, the phosphoric acid group preferably includes a structure represented by the following formula (2).

* represents a bond.

＊は結合手を表す。 Preferably, at least a portion of the repeating units of the fluorine microporous polymer include a 1,4-dioxin structure. For example, some of the repeating units of the fluorine microporous polymer contain a 1,4-dioxin structure, and other repeating units of the fluorine microporous polymer contain a structure other than the 1,4-dioxin structure. Alternatively, all of the repeating units of the fluorine microporous polymer may contain a 1,4-dioxin structure. The 1,4-dioxin structure refers to dibenzo-1,4-dioxin represented by the following formula (15). Ar represents an aromatic group. The 1,4-dioxin structure may have a substituent.

* represents a bond.

Examples of the aromatic group include aromatic groups such as a monocyclic structure, a polycyclic structure, and a condensed ring structure. Further, the aromatic group may have a substituent.

Examples of substituents for the aromatic group include a fluorine atom, an alkyl group, a fluorine-substituted alkyl group, a phenyl group, a fluorine-substituted phenyl group, an aryl group, a phenoxy group, and an alkoxy group.

式中、Ｒ^２は、例えば、－Ｏ－、－Ｓ－、－Ｃ（＝Ｏ）－、－ＳＯ_２－、－Ｃ（ＣＨ_３）_２－、－Ｃ_２Ｈ_４－、－Ｃ（ＣＦ_３）_２－、－Ｃ_２Ｆ_４－、－Ｃ_４Ｆ_８－、－Ｃ_６Ｆ_１２－、－Ｃ_８Ｆ_１６－、－Ｃ_６Ｈ_４－、－Ｃ_６Ｆ_４－等の２価有機基を表す。 Specific examples of Ar in formula (15) include the following aromatic groups.

In the formula, R ² is, for example, -O-, -S-, -C(=O)-, -SO ₂ -, -C(CH ₃ ) ₂ -, -C ₂ H ₄ -, -C(CF ₃ ) Bivalents such as _2- , -C ₂ F ₄ -, -C ₄ F ₈ -, -C ₆ F ₁₂ -, -C ₈ F ₁₆ -, -C ₆ H ₄ -, -C ₆ F ₄ -, etc. Represents an organic group.

式中、
Ａｒ^１は、下記で表されるいずれか１つの構造を表す。

Ａｒ^２は、下記で表されるいずれか１つの構造を表す。

Ｒ^１は、それぞれ独立に、水素、ハロゲン基、シアノ基、ニトリル基、ニトロ基、ヒドロキシ基、置換もしくは非置換のアルキル基、置換もしくは非置換のシクロアルキル基、置換もしくは非置換のアルコキシ基、置換もしくは非置換のアリール基を表す。
ｍは０または１である。
ｘは０＜ｘ≦６であり、ｙは０≦ｙ＜６であり、ｘ＋ｙ≦６である。
Ａは、下記の構造のいずれかを表す。

式中、
Ｚは、Ｈ、Ｃｌ、Ｆ、又は炭素数１～３のパーフルオロアルキル基を表す。
ｐは０または１、ｑは０～２の整数、ｒは０～１２の整数を表す。ただし、ｑ及びｒは同時に０にならない。
ｓは０または１、ｔは０または１を表す。
Ｙは、Ｆ、又はエーテル結合性酸素原子を有してもよい炭素数１～６のパーフルオロアルキル基を表す。
Ｒ_ｆは、それぞれ独立にエーテル結合性酸素原子を含む炭素数１～１０のフッ素化炭化水素基を表す。
＊は結合手を表す。 Examples of the fluorine-containing microporous polymer include a skeleton including a structure represented by the following formula (3), and it is preferable that the repeating unit includes the structure represented by the following formula (3).

During the ceremony,
Ar ¹ represents any one structure represented below.

Ar ² represents any one structure represented below.

R ¹ is each independently hydrogen, a halogen group, a cyano group, a nitrile group, a nitro group, a hydroxy group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted alkoxy group, Represents a substituted or unsubstituted aryl group.
m is 0 or 1.
x is 0<x≦6, y is 0≦y<6, and x+y≦6.
A represents any of the structures below.

During the ceremony,
Z represents H, Cl, F, or a perfluoroalkyl group having 1 to 3 carbon atoms.
p represents 0 or 1, q represents an integer of 0 to 2, and r represents an integer of 0 to 12. However, q and r do not become 0 at the same time.
s represents 0 or 1, and t represents 0 or 1.
Y represents F or a perfluoroalkyl group having 1 to 6 carbon atoms which may have an ether-bonding oxygen atom.
R _f each independently represents a fluorinated hydrocarbon group having 1 to 10 carbon atoms and containing an ether-bonding oxygen atom.
* represents a bond.

In the present disclosure, an Fv(A)w(B)x group bonded to two aromatic rings indicates the number v, w or x of each substituent at a position that can be directly bonded to the aromatic ring, It shows that the positions of the substituents F, (A) and (B) are arbitrary. Therefore, the structure of Ar ² having the above F _6-xy (OA) _x (OH) _y group has x (OA) groups directly bonded to any position of the aromatic ring, and This means that it has y OH groups directly bonded to any position of the aromatic ring, and 6-xy F groups directly bonded to any position of the aromatic ring. Similarly, the structure of Ar ² having the above F _6-x (PO ₃ H ₂ ) _x group has x (PO ₃ H ₂ ) groups directly bonded to any position of the aromatic ring, and It means having 6-x F groups directly bonded to any position of the group ring. The same applies to structures having substituents bonded to two other aromatic rings.

ｘは０＜ｘ≦６であり、ｙは０≦ｙ＜６であり、ｘ＋ｙ≦６である。
ｘは、プロトン伝導性と熱水耐性の観点から、０．１≦ｘ≦５．０が好ましく、０．３≦ｘ≦４．０がより好ましく、０．５≦ｘ≦３．０が更に好ましい。
ｙは、耐熱性の観点から、０≦ｙ≦３が好ましく、０≦ｙ≦１がより好ましく、０≦ｙ≦０．５が更に好ましい。ｘおよびｙは、それぞれ、ＮＭＲおよびＥＷ測定より算出できる。 From the viewpoint of oxygen solubility, Ar ² preferably has a structure represented by any one of the following formulas (4) to (8). In the structures of formulas (4) to (8), the side chains having sulfonic acid groups are short, which increases the voids formed in the polymer electrolyte and increases the oxygen solubility. Further, from the viewpoint of ease of synthesis, Ar ² is more preferably a structure represented by any one of the following formulas (5), (6), and (8).

x is 0<x≦6, y is 0≦y<6, and x+y≦6.
From the viewpoint of proton conductivity and hot water resistance, x is preferably 0.1≦x≦5.0, more preferably 0.3≦x≦4.0, and even more preferably 0.5≦x≦3.0. preferable.
From the viewpoint of heat resistance, y is preferably 0≦y≦3, more preferably 0≦y≦1, and even more preferably 0≦y≦0.5. x and y can be calculated from NMR and EW measurements, respectively.

From the viewpoint of ease of synthesis, Ar ¹ is preferably one of the structures shown below.

The fluorine-containing microporous polymer may contain other structures in addition to the structure represented by formula (3). The fluorine-containing microporous polymer may be a copolymer having at least one selected from the group consisting of different Ar ¹ and Ar ² .

(Characteristic)
The polymer electrolyte preferably has an equivalent weight EW (dry mass in grams of the polymer electrolyte per equivalent of proton exchange group) of 100 to 2000 g/eq. That is, it is preferable to control the copolymerization ratio and the protonic conductive group introduction rate so that they fall within the above range of EW. When the EW is within the above range, the polymer electrolyte has better processability, the conductivity of the electrode catalyst layer does not become too low, and the solubility in hot water is low. The upper limit of EW is more preferably 1000 g/eq, still more preferably 900 g/eq. The lower limit of EW is more preferably 300 g/eq, still more preferably 500 g/eq. EW can be calculated by the method described in Examples below.

The polymer electrolyte preferably has a weight average molecular weight of 1,000 to 2,000,000, since the processability, electrical conductivity, and mechanical strength of the polymer electrolyte are even more excellent. More preferably 5,000 to 1,000,000, still more preferably 10,000 to 700,000,000.

The weight average molecular weight is a value measured by GPC (gel permeation chromatography), and the number average molecular weight can be calculated based on standard polystyrene by the method shown below, for example.

An example of the GPC method: TOSOH HLC-8020 was used, and the columns were 3 Shodex Super HM-M, 60°C, DMAc (containing 50 mmol/L LiBr) solvent, or the columns were Shodex Super K-806H and K-803L. It can be carried out using a chloroform solvent at 35° C. at a flow rate of 1.0 mL/min. The sample concentration can be 0.1% by weight and the injection amount can be 100 μL.

If the molecular weight cannot be measured by GPC, it may be measured by melt flow rate (MFR).

The MFR of the polymer electrolyte is preferably 0.1 to 1,000 g/10 minutes, more preferably 0.5 g/10 minutes or more, and even more preferably 1.0 g/10 minutes or more. , more preferably 200 g/10 minutes or less, and even more preferably 100 g/10 minutes or less.

MFR can be measured, for example, using MELT INDEXER TYPE C-5059D (trade name, manufactured by Toyo Seiki Co., Ltd.) under the conditions of 270° C. and a load of 2.16 kg according to ASTM standard D1238.

From the viewpoint of battery performance, it is preferable that the polymer electrolyte has an oxygen solubility of 7.0 mol/m ³ or more as measured by the Pt thick film method at 80° C. and 30% RH. The thin film of polymer electrolyte that covers the catalyst surface is approximately several nm thick, and its oxygen permeability differs from the behavior in the bulk. That is, oxygen diffusivity is rate-determining in the bulk, but oxygen solubility is rate-determining in the thin film. Oxygen solubility can be calculated by the method described in Examples below.

The specific surface area determined by the BET method can be used as an index of voids in the polymer electrolyte. The specific surface area can be calculated by the method described below. From the viewpoint of oxygen permeability, the specific surface area of the polymer electrolyte measured by the BET method is preferably 250 m ² /g or more, more preferably 300 m ² /g or more, and preferably 350 m ² /g or more. Most preferred. From the viewpoint of binder adhesion, the specific surface area is preferably 6,000 m ² /g or less, more preferably 2,000 m ² /g or less, and 1,000 m ² /g or less. Most preferred.

(Production method of polymer electrolyte)
The fluorine-containing microporous polymer electrolyte having sulfonic acid groups can be obtained, for example, by the following first and second production methods. Further, a fluorine-containing microporous polymer electrolyte having a phosphoric acid group can be obtained, for example, by the following third manufacturing method.

First manufacturing method The first manufacturing method is
(i) SO ₃ X group (wherein, X is an alkali metal , an alkaline earth metal, or NR ¹ R ² R ³ R ⁴ ; R ¹ , R ² , R ³ , and R ⁴ are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms. ) using a compound having SO ₃ X groups to obtain a fluorine-containing microporous polymer having SO ₃ X groups;
(ii) converting the SO ₃ X group of the fluorine-containing microporous polymer having the SO ₃ X group into a sulfonic acid group;
It is characterized by including.

(i) Step (i) In the step (i), a SO ₃ X group (formula where X is an alkali metal, ^an alkaline earth metal, or ^{NR 1} R ^{2 R 3 R 4} ; SO ₃ X group is introduced using a compound having _an alkyl group of .

式中、
ｎは整数で、構造単位の繰り返し数を表す。
Ａｒは芳香族基を表す。
Ｒ^３は、ハロゲン原子を表す。
ただし、モノマー（Ｍ３）のＡｒに結合している１個以上のフッ素原子は省略している。 As a method for obtaining the fluorine-containing microporous polymer (P1), for example, a fluorine-containing microporous polymer (P1) having an aromatic group and having four or more halogen atoms and one or more fluorine atoms bonded to the carbon atom of the aromatic group can be used. Using a fluorine aromatic monomer (M3) and an aromatic monomer (M4) having an aromatic group and having four or more hydroxyl groups bonded to the carbon atom of the aromatic group, in the presence of a catalyst, the monomer (M3) Examples include a method of condensation polymerization of the halogen atom of and the hydroxyl group of the monomer (M4). In the following formula 16, as an example, a monomer (M3) having four halogen atoms bonded to an aromatic group and a monomer (M4) having four hydroxyl groups bonded to an aromatic group are included by condensation polymerization. The formation of a fluorine microporous polymer (P1) is shown.

During the ceremony,
n is an integer and represents the number of repeats of the structural unit.
Ar represents an aromatic group.
R ³ represents a halogen atom.
However, one or more fluorine atoms bonded to Ar of the monomer (M3) are omitted.

Examples of the aromatic group of Ar include aromatic groups such as a monocyclic structure, a polycyclic structure, and a condensed ring structure. Further, the aromatic group may have a substituent.

Examples of the halogen atom for R ³ include a fluorine atom, a chlorine atom, a bromine atom, and the like.

As the fluorine-containing aromatic monomer (M3), known monomers can be used, but from the viewpoint of oxygen solubility, any of the monomers represented by formula (17) is preferable. From the viewpoint of ease of synthesis, the monomer (M3) is more preferably a monomer represented by the following formula (18).

As the aromatic monomer (M4), any known monomer can be used, but from the viewpoint of oxygen solubility, it is preferably one of the monomers represented by the following formula (14). From the viewpoint of ease of synthesis, the monomer (M4) is more preferably any of the monomers represented by the following formula (19).

The condensation polymerization of monomer (M3) and monomer (M4) is preferably carried out in a polar solvent in the presence of a basic catalyst.

As the basic catalyst, for example, carbonates, hydrogen carbonates, or hydroxides of alkali metals or alkaline earth metals are preferable. Specific examples of these basic catalysts include sodium carbonate, potassium carbonate, cesium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, sodium hydroxide, potassium hydroxide, and cesium hydroxide.

The amount of the basic catalyst added is preferably 0.1 to 12 equivalents, more preferably 0.5 to 8 equivalents, and most preferably 1 to 4 equivalents, based on the monomer (M4).

Examples of the polar solvent include aprotic polar solvents such as N,N-dimethylacetamide, N,N-dimethylformamide, N-methylpyrrolidone, dimethylsulfoxide, and 1,3-dimethyl-2-imidazolidinone. Solvents that do are preferred. As the polar solvent, for example, toluene, xylene, benzene, benzotrifluoride, xylene hexafluoride, etc. may be used as long as it does not reduce the solubility of the fluorine-containing microporous polymer to be produced and does not adversely affect the condensation polymerization. May be included.

The reaction temperature for condensation polymerization is preferably 10 to 300°C, more preferably 30 to 240°C, and most preferably 60 to 200°C.

The reaction time for condensation polymerization is preferably 1 to 80 hours, more preferably 2 to 60 hours, and most preferably 3 to 48 hours.

The fluorine-containing microporous polymer (P1) preferably has a weight average molecular weight of 1,000 to 2,000,000, and more preferably The number is preferably 5,000 to 1,000,000, more preferably 10,000 to 7,000,000. The molecular weight of P1 can be controlled, for example, by changing the charging ratio of monomer (M3) and monomer (M4) during condensation polymerization, or by controlling the reaction temperature and reaction time.

Condensation polymerization may be performed by adding one or more other monomers to the monomer (M3) and monomer (M4) described above.

式中、Ｚは、Ｈ、Ｃｌ、Ｆ、又は炭素数１～３のパーフルオロアルキル基を表す。
ｑは０～２の整数、ｒは０～１２の整数を表す。ただし、ｑ及びｒは同時に０にならない。
ｔは０または１を表す。
Ｙは、Ｆ、又はエーテル結合性酸素原子を有してもよい炭素数１～６のパーフルオロアルキル基を表す。
Ｒ_ｆは、それぞれ独立にエーテル結合性酸素原子を含む炭素数１～１０のフッ素化炭化水素基を表す。
Ｘは、アルカリ金属、アルカリ土類金属、又はＮＲ^１Ｒ^２Ｒ^３Ｒ^４である。
Ｒ^１、Ｒ^２、Ｒ^３、及びＲ^４は、それぞれ独立して、水素、又は炭素数１～４のアルキル基である。 ^SO ₃ ^{_ _ _ _ _ _ _} The compound having an alkyl group having 1 to 4 carbon atoms preferably has a structure represented by the following formula (9) or (10), for example. As shown in formulas (9) and (10), when the hydrocarbon adjacent to the sulfonic acid group is fluorine-containing, acidity increases, proton conductivity improves, and contributes to high power generation performance.

In the formula, Z represents H, Cl, F, or a perfluoroalkyl group having 1 to 3 carbon atoms.
q represents an integer of 0 to 2, and r represents an integer of 0 to 12. However, q and r do not become 0 at the same time.
t represents 0 or 1.
Y represents F or a perfluoroalkyl group having 1 to 6 carbon atoms which may have an ether-bonding oxygen atom.
R _f each independently represents a fluorinated hydrocarbon group having 1 to 10 carbon atoms and containing an ether-bonding oxygen atom.
X is an alkali metal, an alkaline earth metal, or NR ¹ R ² R ³ R ⁴ .
R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms.

Examples of the alkali metal of X include lithium, sodium, potassium, rubidium, and cesium.

Examples of the alkaline earth metal of X include magnesium and calcium.

_Specific examples of compounds having _an SO _{3 X group include} CF ₂ =CF-OCF _{2 CF 2 SO 3} Examples include CF-OCF ₂ CF (CF ₂ OCF ₂ CF ₂ SO ₃ X)-OCF ₂ CF ₂ SO ₃ X.

式中、
Ｘは、アルカリ金属、アルカリ土類金属、又はＮＲ^１Ｒ^２Ｒ^３Ｒ^４である。
Ｒ^１、Ｒ^２、Ｒ^３、及びＲ^４は、それぞれ独立して、水素、又は炭素数１～４のアルキル基である。 The compound having an SO ₃ X group preferably has a structure represented by the following formula (11) from the viewpoint of oxygen solubility. In formula (11), since the structure of the compound having an SO ₃ X group is small, the voids formed in the polymer electrolyte become large and the oxygen solubility increases.

During the ceremony,
X is an alkali metal, an alkaline earth metal, or NR ¹ R ² R ³ R ⁴ .
R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms.

Since the compound having an SO ₃ The OW group of the porous polymer is added to the double bond of the fluorine-containing sulfonic acid derivative to obtain a fluorine-containing microporous polymer having an SO ₃ X group.

The amount of SO ₃ X group introduced can be adjusted by the amount of the compound having SO ₃ X group, reaction temperature, and reaction time.

The amount of the compound having _an SO ₃ ), preferably 0.1 to 20 equivalents, more preferably 1 to 10 equivalents, and most preferably 1.1 to 5 equivalents.

Various crown ethers may be added to improve the solubility of the compound having an SO ₃ X group in a solvent. Specific examples of crown ethers include 15-crown-5 and 18-crown-6. The amount of crown ether added is preferably 0.01 to 10 equivalents, more preferably 0.01 to 5 equivalents, and most preferably 0.01 to 3 equivalents, based on the compound having an SO ₃ X group.

When introducing an OW group into a fluorine-containing microporous polymer, a base may be added in order to efficiently add the OW group to the double bond of a compound having an SO ₃ X group. As the base, bulky bases such as sodium hydride, potassium t-butoxy, sodium t-butoxy, and lithium diisopropylamide are preferred. By being a bulky base, side reactions such as nucleophilic attacks on double bonds by the base can be suppressed. From the viewpoint of suppressing side reactions, a method is preferred in which a fluorine-containing microporous polymer having an OW group is reacted with a base, and then a compound having an SO ₃ X group is added.

The amount of the base to be added is based on the repeating unit of the fluorine-containing microporous polymer (P1) (the repeating unit into which an SO ₃ X group is introduced, for example, the repeating unit having a 1,4-dioxin structure), 0.01 to 10 equivalents are preferred, 0.1 to 5 equivalents are more preferred, and 0.5 to 3 equivalents are most preferred.

Although general organic solvents can be used as the solvent in the reaction for introducing the SO ₃ Examples of the solvent include tetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, N,N-dimethylacetamide, N,N-dimethylformamide, N- Examples include methylpyrrolidone, dimethylsulfoxide, 1,3-dimethyl-2-imidazolidinone, and the like.

The reaction temperature is preferably 30 to 200°C, more preferably 40 to 160°C, and most preferably 50 to 120°C.

The reaction time is preferably 1 to 80 hours, more preferably 2 to 60 hours, and most preferably 3 to 24 hours.

In the first manufacturing method, the step (i) is
(iii) An OW group (in the formula, W is hydrogen, an alkali metal, or an alkaline earth metal) is introduced into the fluorine-containing microporous polymer (P1) to create a fluorine-containing microporous polymer having an OW group. obtaining a porous polymer;
(iv) reacting the fluorine-containing microporous polymer having the OW group with the compound having the SO ₃ X group to obtain the fluorine-containing microporous polymer having the SO ₃ X group;
It is preferable to include.

(iii) Step (iii) In the step (iii), an OW group is introduced into the fluorine-containing microporous polymer (P1) to obtain a fluorine-containing microporous polymer having an OW group. As a method for introducing the OW group, P1 is treated with an alkali metal hydroxide or an alkaline earth metal hydroxide (hereinafter, in step (iii), an alkali metal hydroxide and an alkaline earth metal hydroxide). One example is a method of reacting a substance (simply referred to as a "hydroxide"). Specific examples of such hydroxides include sodium hydroxide, potassium hydroxide, cesium hydroxide, and the like.

The amount of OW groups introduced can be adjusted by adjusting the amount of hydroxide added, reaction temperature, and reaction time. The amount of OW group introduced can be calculated from NMR.

The amount of hydroxide added is determined from the viewpoint of the amount of OW group introduced, relative to the repeating unit of P1 (the repeating unit into which the SO ₃ X group is introduced, for example, the repeating unit having a 1,4-dioxin structure). , preferably 0.1 to 10 equivalents, more preferably 0.5 to 5 equivalents, most preferably 1 to 3 equivalents.

When the solubility of hydroxide in a solvent is low, various crown ethers can be added. Specific examples of crown ethers include 15-crown-5 and 18-crown-6. The amount of crown ether added is preferably 0.01 to 10 equivalents, more preferably 0.5 to 5 equivalents, and most preferably 1 to 3 equivalents or less relative to the hydroxide.

As the solvent in step (iii), common organic solvents can be used, such as tetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, N,N-dimethylacetamide, N,N-dimethylformamide, N-methylpyrrolidone, dimethylsulfoxide, 1,3-dimethyl-2-imidazolidinone and the like are preferred from the viewpoint of solubility. A small amount of water may be added to dissolve the alkali metal hydroxide or alkaline earth metal hydroxide.

The reaction temperature in step (iii) is preferably 30 to 200°C, more preferably 40 to 160°C, most preferably 50 to 120°C.

The reaction time in step (iii) is preferably 1 to 80 hours, more preferably 2 to 60 hours, and most preferably 3 to 24 hours.

(iv) In the step (iv), a fluorine-containing microporous polymer having an OW group is reacted with a compound having an SO ₃ X group to obtain a fluorine-containing microporous polymer having an SO ₃ X group. . As described above, when the compound having an SO ₃ X group has a double bond, an OW group is added to the double bond to obtain a fluorine-containing microporous polymer having an SO ₃

The base and solvent used in step (iv), and the reaction temperature and reaction time in step (iv) are the same as described in step (i).

Step (ii) In the step (ii), the SO ₃ X groups of the fluorine-containing microporous polymer having SO ₃ X groups are converted into sulfonic acid groups. Although there are no particular limitations on the method as long as it is possible to convert the SO ₃ X group into a sulfonic acid group, it is preferable to ion-exchange the X of the SO ₃

The ion exchange method is not particularly limited, but for example, a method in which a fluorine-containing microporous polymer having SO ₃ X groups is treated with an excessive amount of an aqueous or alcoholic solution of hydrochloric _acid , and A method of passing a solution of a fluorine-containing microporous polymer having a cation exchange resin through a cation exchange resin can be mentioned.

The amount of sulfonic acid groups introduced can be calculated from NMR and EW.

Second manufacturing method The second manufacturing method is
(a) An aromatic group, four or more halogen atoms bonded to the carbon atoms of the aromatic group, and an SO ₃ X group (X is an alkali metal, an alkaline earth metal, or NR ¹ R ² R ³ R ⁴ , and R ¹ , R ² , R ³ , and R ⁴ are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms) and one or more fluorine atoms. a step of preparing a group monomer (M1), an aromatic monomer (M2) having an aromatic group and four or more hydroxyl groups bonded to a carbon atom of the aromatic group;
(b) Condensation polymerization of the halogen atom of the aromatic monomer (M1) and the hydroxyl group of the aromatic monomer (M2) in the presence of a catalyst to obtain a fluorine-containing microporous polymer having an SO ₃ X group process and
(c) converting the SO ₃ X group of the fluorine-containing microporous polymer having the SO ₃ X group into a sulfonic acid group;
It is characterized by including.

(A) Step (A) In step (A), an aromatic group, four or more halogen atoms bonded to the carbon atoms of the aromatic group, and an SO ₃ X group (X is an alkali metal, an alkaline earth metal, or ^{and one or more _ _ _ _} An aromatic monomer (M1) having a fluorine atom; and an aromatic monomer (M2) having an aromatic group and four or more hydroxyl groups bonded to the carbon atoms of the aromatic group are prepared.

Aromatic monomer (M1)
The aromatic group of the monomer (M1) is the same as the aromatic group explained for Ar in formula (15) above. The substituents of the aromatic group are also the same as those explained for Ar.

The monomer (M1) has four or more halogen atoms bonded to the carbon atoms of its aromatic group. From the viewpoint of polymerizability, four of the halogen atoms bonded to the carbon atoms of the aromatic group of the monomer (M1) are preferably fluorine atoms. The monomer (M1) has one or more fluorine atoms in addition to the four or more halogen atoms.

式中、
Ｒ^１は、それぞれ独立に、水素、ハロゲン基、シアノ基、ニトリル基、ニトロ基、ヒドロキシ基、置換もしくは非置換のアルキル基、置換もしくは非置換のシクロアルキル基、置換もしくは非置換のアルコキシ基、置換もしくは非置換のアリール基を表す。
ｍは０または１であり、Ｂは、下記のいずれかの構造を表す。

Ｚは、Ｈ、Ｃｌ、Ｆ、又は炭素数１～３のパーフルオロアルキル基を表す。
ｐは０または１を表し、ｑは０～２の整数を表し、ｒは０～１２の整数を表す。ただし、ｑ及びｒは同時に０にならない。
ｓは０または１を表し、ｔは０または１を表す。
Ｙは、Ｆ、又はエーテル結合性酸素原子を有してもよい炭素数１～６のパーフルオロアルキル基を表す。
Ｒ_ｆは、それぞれ独立にエーテル結合性酸素原子を含む炭素数１～１０のフッ素化炭化水素基を表す。
Ｘは、アルカリ金属、アルカリ土類金属、又はＮＲ^１Ｒ^２Ｒ^３Ｒ^４である。
Ｒ^１、Ｒ^２、Ｒ^３、及びＲ^４は、それぞれ独立して、水素、又は炭素数１～４のアルキル基である。
＊は結合手を表す。 From the viewpoint of ease of synthesis, the monomer (M1) preferably has any one structure represented by the following (12).

During the ceremony,
R ¹ is each independently hydrogen, a halogen group, a cyano group, a nitrile group, a nitro group, a hydroxy group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted alkoxy group, Represents a substituted or unsubstituted aryl group.
m is 0 or 1, and B represents any of the following structures.

Z represents H, Cl, F, or a perfluoroalkyl group having 1 to 3 carbon atoms.
p represents 0 or 1, q represents an integer from 0 to 2, and r represents an integer from 0 to 12. However, q and r do not become 0 at the same time.
s represents 0 or 1, and t represents 0 or 1.
Y represents F or a perfluoroalkyl group having 1 to 6 carbon atoms which may have an ether-bonding oxygen atom.
R _f each independently represents a fluorinated hydrocarbon group having 1 to 10 carbon atoms and containing an ether-bonding oxygen atom.
X is an alkali metal, an alkaline earth metal, or NR ¹ R ² R ³ R ⁴ .
R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms.
* represents a bond.

式中、
Ｘは、アルカリ金属、アルカリ土類金属、又はＮＲ^１Ｒ^２Ｒ^３Ｒ^４である。
Ｒ^１、Ｒ^２、Ｒ^３、及びＲ^４は、それぞれ独立して、水素、又は炭素数１～４のアルキル基である。 From the viewpoint of oxygen solubility, the monomer (M1) preferably has any one structure represented by the following formula (13). In the structure of formula (13), because the side chain having the SO ₃ X group is short, the voids formed in the polymer electrolyte become larger and the oxygen solubility increases. Further, from the viewpoint of polymerizability, it is more preferable to have any of the structures represented by the following formula (20). In the structure of formula (20), the presence of an electron-withdrawing group facilitates the progress of condensation polymerization.

During the ceremony,
X is an alkali metal, an alkaline earth metal, or NR ¹ R ² R ³ R ⁴ .
R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms.

The alkali metal and alkaline earth metal of X are the same as those of the SO ₃ X group.

(Synthesis of aromatic monomer M1)
Monomer (M1) can be synthesized, for example, by the following two methods.

式中、
Ｒ^１は、それぞれ独立に、水素、ハロゲン基、シアノ基、ニトリル基、ニトロ基、ヒドロキシ基、置換もしくは非置換のアルキル基、置換もしくは非置換のシクロアルキル基、置換もしくは非置換のアルコキシ基、置換もしくは非置換のアリール基を表す。
Ｂは、下記のいずれかの構造を表す。

Ｚは、Ｈ、Ｃｌ、Ｆ、又は炭素数１～３のパーフルオロアルキル基を表す。
ｐは０または１を表し、ｑは０～２の整数を表し、ｒは０～１２の整数を表す。ただし、ｑ及びｒは同時に０にならない。
ｓは０または１を表し、ｔは０または１を表す。
Ｙは、Ｆ、又はエーテル結合性酸素原子を有してもよい炭素数１～６のパーフルオロアルキル基を表す。
Ｒ_ｆは、それぞれ独立にエーテル結合性酸素原子を含む炭素数１～１０のフッ素化炭化水素基を表す。Ｘは、アルカリ金属、アルカリ土類金属、又はＮＲ^１Ｒ^２Ｒ^３Ｒ^４である。
Ｒ^１、Ｒ^２、Ｒ^３、及びＲ^４は、それぞれ独立して、水素、又は炭素数１～４のアルキル基である。
＊は結合手を表す。 The first method for synthesizing the monomer (M1) is a method of reacting a corresponding phenol with a compound having an SO ₃ X group (Formula 21).

During the ceremony,
R ¹ is each independently hydrogen, a halogen group, a cyano group, a nitrile group, a nitro group, a hydroxy group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted alkoxy group, Represents a substituted or unsubstituted aryl group.
B represents any of the following structures.

Z represents H, Cl, F, or a perfluoroalkyl group having 1 to 3 carbon atoms.
p represents 0 or 1, q represents an integer from 0 to 2, and r represents an integer from 0 to 12. However, q and r do not become 0 at the same time.
s represents 0 or 1, and t represents 0 or 1.
Y represents F or a perfluoroalkyl group having 1 to 6 carbon atoms which may have an ether-bonding oxygen atom.
R _f each independently represents a fluorinated hydrocarbon group having 1 to 10 carbon atoms and containing an ether-bonding oxygen atom. X is an alkali metal, an alkaline earth metal, or NR ¹ R ² R ³ R ⁴ .
R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms.
* represents a bond.

式中、Ｚは、Ｈ、Ｃｌ、Ｆ、又は炭素数１～３のパーフルオロアルキル基を表す。
ｑは０～２の整数、ｒは０～１２の整数を表す。ただし、ｑ及びｒは同時に０にならない。
ｔは０または１を表す。
Ｙは、Ｆ、又はエーテル結合性酸素原子を有してもよい炭素数１～６のパーフルオロアルキル基を表す。
Ｒ_ｆは、それぞれ独立にエーテル結合性酸素原子を含む炭素数１～１０のフッ素化炭化水素基を表す。
Ｘは、アルカリ金属、アルカリ土類金属、又はＮＲ^１Ｒ^２Ｒ^３Ｒ^４である。
Ｒ^１、Ｒ^２、Ｒ^３、及びＲ^４は、それぞれ独立して、水素、又は炭素数１～４のアルキル基である。 The compound having an SO ₃ X group preferably has a structure represented by the following formula (9) or (10). As shown in formulas (9) and (10), when the hydrocarbon adjacent to the sulfonic acid group is fluorine-containing, acidity increases, proton conductivity improves, and contributes to high power generation performance.

In the formula, Z represents H, Cl, F, or a perfluoroalkyl group having 1 to 3 carbon atoms.
q represents an integer of 0 to 2, and r represents an integer of 0 to 12. However, q and r do not become 0 at the same time.
t represents 0 or 1.
Y represents F or a perfluoroalkyl group having 1 to 6 carbon atoms which may have an ether-bonding oxygen atom.
R _f each independently represents a fluorinated hydrocarbon group having 1 to 10 carbon atoms and containing an ether-bonding oxygen atom.
X is an alkali metal, an alkaline earth metal, or NR ¹ R ² R ³ R ⁴ .
R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms.

The alkali metal and alkaline earth metal of X are the same as those of X explained in the first manufacturing method.

_Specific examples of compounds having _an SO _{3 X group include} CF ₂ =CF-OCF _{2 CF 2 SO 3} Examples include CF-OCF ₂ CF (CF ₂ OCF ₂ CF ₂ SO ₃ X)-OCF ₂ CF ₂ SO ₃ X.

The compound having the SO ₃ X group preferably has a structure represented by the following formula (11) from the viewpoint of oxygen solubility. In formula (11), since the structure of the compound having an SO ₃ X group is small, the voids formed in the polymer electrolyte become large and the oxygen solubility increases.

In the synthesis of the monomer (M1), the compound having an _{SO 3} A monomer (M1) having an X group can be obtained.

In the first method for synthesizing the monomer (M1), it is preferable to carry out the reaction using an equivalent or more amount of phenol with respect to the compound having an SO ₃ X group. Specifically, the hydroxyl group of the phenol is preferably 1.0 to 10 equivalents, more preferably 1.1 to 5 equivalents, and 1.2 to 3.0 equivalents relative to the compound having an SO ₃ X group. Most preferred. When the amount of phenols is 1.0 equivalent or more, the desired reaction proceeds selectively. Moreover, since the amount added is 10 equivalents or less, the load on the purification process is reduced.

In the first method for synthesizing the monomer (M1), it is preferable to add a base in order to allow the reaction to proceed efficiently. As the base, bulky bases such as sodium hydride, potassium t-butoxy, sodium t-butoxy, and lithium diisopropylamide are preferred. By being a bulky base, side reactions such as nucleophilic attack on the double bond site of a compound having an SO ₃ X group by the base can be suppressed. From the viewpoint of suppressing side reactions, it is preferable to first react the hydroxyl group of the phenol with a base to generate phenoxide, and then add the compound having an SO ₃ X group.

The amount of the base added is preferably 0.1 to 5.0 equivalents, more preferably 0.1 to 2.0 equivalents, and most preferably 0.1 to 1.0 equivalents, based on the hydroxyl group of the phenol.

Although general organic solvents can be used as the solvent in the first method of synthesizing the monomer (M1), aprotic solvents are preferred from the viewpoint of suppressing side reactions to the double bond site. Examples of the solvent include tetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, N,N-dimethylacetamide, N,N-dimethylformamide, N- Examples include methylpyrrolidone, dimethylsulfoxide, 1,3-dimethyl-2-imidazolidinone, and the like.

The reaction temperature in the first method for synthesizing the monomer (M1) is preferably 30 to 200°C, more preferably 40 to 160°C, and most preferably 50 to 120°C.

The reaction time for the first method of synthesizing the monomer (M1) is preferably 1 to 80 hours, more preferably 2 to 60 hours, and most preferably 3 to 24 hours.

The obtained monomer (M1) may be further purified. Purification methods include, but are not particularly limited to, liquid separation extraction, crystallization, reprecipitation, column chromatography, and the like.

式中、
Ｒ^１は、それぞれ独立に、水素、ハロゲン基、シアノ基、ニトリル基、ニトロ基、ヒドロキシ基、置換もしくは非置換のアルキル基、置換もしくは非置換のシクロアルキル基、置換もしくは非置換のアルコキシ基、置換もしくは非置換のアリール基を表す。
Ｒ_ｆは、エーテル結合性酸素原子を含む炭素数１～１０のフッ素化炭化水素基を表す。
Ｘは、アルカリ金属、アルカリ土類金属、又はＮＲ^１Ｒ^２Ｒ^３Ｒ^４である。
Ｒ^１、Ｒ^２、Ｒ^３、及びＲ^４は、それぞれ独立して、水素、又は炭素数１～４のアルキル基である。 A second method for synthesizing the monomer (M1) includes a dehalogen coupling reaction using a copper catalyst (Formula 22).

During the ceremony,
R ¹ is each independently hydrogen, a halogen group, a cyano group, a nitrile group, a nitro group, a hydroxy group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted alkoxy group, Represents a substituted or unsubstituted aryl group.
R _f represents a fluorinated hydrocarbon group having 1 to 10 carbon atoms and containing an ether-bonding oxygen atom.
X is an alkali metal, an alkaline earth metal, or NR ¹ R ² R ³ R ⁴ .
R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms.

In the second synthesis method of the monomer (M1), for example, by referring to Journal of Fluorine Chemistry, 2016, 189, 43-50, 4-trifluoromethyl is newly synthesized as shown in the following formula (23). - Using potassium 2,3,5,6-tetrafluorobromobenzene and 1,1,2,2-tetrafluoro-2-(1,1,2,2-tetrafluoro-2-iodoethoxy)ethanesulfonate In this way, an aromatic monomer (M1) having an SO ₃ X group can be obtained.

Aromatic monomer (M2)
The aromatic group of the monomer (M2) is the same as the aromatic group explained for Ar in formula (15) above. The substituents of the aromatic group are also the same as those explained for Ar.

The monomer (M2) has four or more hydroxyl groups bonded to the carbon atoms of its aromatic group.

As the aromatic monomer (M2), any known monomer can be used, but from the viewpoint of oxygen solubility, it is preferably one of the monomers represented by the following formula (14). From the viewpoint of ease of synthesis, any of the monomers represented by the following formula (19) is more preferable.

(B) Step (B) In the step (B), the halogen atom of the aromatic monomer (M1) and the hydroxyl group of the aromatic monomer (M2) are condensed and polymerized in the presence of a catalyst to form fluorine-containing microporous cells having SO ₃ X groups. obtain a polymer.

For details of the catalyst for condensation polymerization of monomer (M1) and monomer (M2), reaction conditions, etc., the above-mentioned first production method can be referred to.

Condensation polymerization may be performed by adding one or more types of other monomers to the monomer (M1) and the monomer (M2).

(c) Step (c) In the step (c), the SO ₃ X groups of the fluorine-containing microporous polymer having SO ₃ X groups are converted into sulfonic acid groups. The method is not particularly limited as long as it can convert the SO ₃ X group into a sulfonic acid group, but
Preferably, X of the SO ₃ X group is ion-exchanged to hydrogen. The ion exchange method is as described in ion exchange in the first manufacturing method.

Third manufacturing method The third manufacturing method is
characterized by comprising a step of reacting tris(trimethylsilyl) phosphite with a fluorine-containing microporous polymer having an aromatic group and one or more fluorine atoms directly bonded to the aromatic group, This is a method for producing a fluorine-containing microporous polymer electrolyte having a phosphoric acid group.

The third manufacturing method is
A step of obtaining a fluorine-containing microporous polymer (P1);
A step of reacting tris(trimethylsilyl) phosphite to the fluorine-containing microporous polymer obtained above to introduce a trimethylsilyl ether group;
a step of converting a trimethylsilyl ether group into a phosphate group by hydrolysis;
It is preferable to include.

The method for obtaining the fluorine-containing microporous polymer (P1) is as described in the first production method.

＊は結合手を表す。 (Introduction of phosphate group)
Regarding the step of reacting the fluorine-containing microporous polymer (P1) with tris(trimethylsilyl) phosphite to introduce a trimethylsilyl ether group, and the step of converting the trimethylsilyl ether group into a phosphoric acid group by hydrolysis, Macromolecules, 2011, 44, 6416-6423 can be referred to. Thereby, a fluorine-containing microporous polymer electrolyte containing a structure represented by the following formula (2) as a phosphoric acid group can be obtained.

* represents a bond.

The fluorine-containing microporous polymer electrolyte of the present invention may contain a basic group-containing metal complex (hereinafter sometimes simply referred to as "metal complex") as an additive. When the fluorine-containing microporous polymer electrolyte contains a basic group-containing metal complex, oxygen solubility is further increased, leading to further improvements in high power generation performance and high chemical durability of the fuel cell.

Examples of metal complexes include Schiff base metal complexes and porphyrinoid metal complexes.

Examples of Schiff base metal complexes include salen metal complexes, among which cobalt salen is difficult to demetalize even in the presence of sulfonic acid, which is a strong acid, and has high acid resistance and excellent oxygen solubility. Additionally, cobalt salen is noteworthy in that it has little poisoning against platinum and is excellent in both battery performance and battery chemical durability.

Examples of porphyrinoid metal complexes include metal complexes consisting of any one of porphyrin derivatives, phthalocyanine derivatives, chlorol derivatives, chlorin derivatives, and phenanthroline derivatives. Among them, cobalt complexes of cobalt fluorine-based phthalocyanine and phenanthroline are acid-resistant and stable. It has excellent oxygen solubility and oxygen solubility. Among these, the cobalt complex of phenanthroline is less poisonous to platinum and has excellent battery performance and battery chemical durability.

In this embodiment, the mixing ratio of the metal complex and the polymer electrolyte is preferably 1 to 15/85 to 99 weight percent, for example. When the proportion of the metal complex is more than 1% by weight, the oxygen solubility effect increases and the battery performance increases. On the other hand, when the proportion of the metal complex is 15% by weight or less, the influence of poisoning on platinum can be suppressed and battery performance can be improved. More preferably, the mixing ratio of the metal complex and the polymer electrolyte is 5 to 10/90 to 95 weight percent.

The metal complex may be immobilized in the fluorine-containing microporous polymer. The immobilization method is not particularly limited, but the following papers can be referred to.
Chemical Communication, 2002, 2780-2781
Chemical Communication, 2002, 2782-2783
Journal of Materials Chemistry, 2003, 13, 2721-2726
Journal of Materials Chemistry, 2005, 15, 1977-1986

The immobilized metal complex may be included in the fluorine-containing microporous polymer electrolyte as an additive. Alternatively, the metal complex can be produced by introducing a sulfonic acid group or a phosphoric acid group into the fluorine atom directly bonded to the aromatic group in the immobilized metal complex using the methods described in the first to third production methods. It may also be a fluorine-containing microporous polymer electrolyte in which is immobilized.

The polymer electrolyte of the present invention can be suitably used as a raw material for forming an electrode catalyst ink.

(Polymer electrolyte solution)
The polymer electrolyte solution of the present embodiment preferably contains the polymer electrolyte of the present invention and at least one selected from the group consisting of water and an organic solvent. The polymer electrolyte solution can be suitably used as a raw material for forming an electrode catalyst layer (for example, a cathode electrode catalyst layer) of a fuel cell. The polymer electrolyte solution is preferably a polymer electrolyte solution for forming an electrode catalyst layer of a fuel cell.

The mass proportion of the polymer electrolyte in the polymer electrolyte solution is preferably 1 to 50% by mass, more preferably 5% by mass or more, even more preferably 10% by mass or more, and even more preferably 40% by mass. It is more preferably at most 30% by mass, even more preferably at most 25% by mass. When the content of the polymer electrolyte in the polymer electrolyte solution is 1% by mass or more, flexibility can be given to the composition preparation of the electrode catalyst ink, and when the content is 50% by mass or less, the polymer electrolyte The viscosity of the electrolyte solution can be stabilized over time.

Examples of organic solvents include protic organic solvents such as methanol, ethanol, n-propanol, isopropyl alcohol, butanol, and glycerin; N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, acetonitrile, and acetic acid. Examples include aprotic solvents such as ethyl; fluorine-based solvents such as trifluoroethanol, Vertrell XF, Novec 7100, and Novec 7300; and the like. These can be used alone or in combination of two or more.

The polymer electrolyte solution may also contain organic additives. Moreover, the polymer electrolyte solution may contain an inorganic additive.

Examples of organic additives include compounds whose atoms are easily extracted by radicals, such as compounds having hydrogen bonded to tertiary carbon, carbon-halogen bonds, etc. in their structures. Specifically, examples of organic additives include aromatic compounds partially substituted with functional groups such as polyaniline, polybenzimidazole, polybenzoxazole, polybenzothiazole, polybenzoxadiazole, and phenylated polyamides. Examples include unsaturated heterocyclic compounds such as quinoxaline and phenylated polyquinoline.

Furthermore, examples of organic additives include thioether compounds. Examples of thioether compounds include dialkylthioethers such as dimethylthioether, diethylthioether, dipropylthioether, methylethylthioether, and methylbutylthioether; cyclic thioethers such as tetrahydrothiophene and tetrahydroapyran; methylphenyl sulfide, ethylphenyl sulfide, Aromatic thioethers such as diphenyl sulfide and dibenzyl sulfide; and the like.

One type of organic additive may be used alone, or a mixture of two or more types may be used.

The mass proportion of the organic additive in the polymer electrolyte solution is preferably 0.1% by mass or more, more preferably 1.0% by mass or more, and even more preferably 3.0% by mass or more. By containing 0.1% by mass or more of the organic additive, it is possible to improve chemical durability during fuel cell operation.

Examples of inorganic additives include metal oxides, metal carbonates, metal nitrates, and the like. One type of inorganic additive may be used alone, or a mixture of two or more types may be used.

Examples of metal oxides include zirconia (ZrO ₂ ), titania (TiO ₂ ), silica (SiO ₂ ), alumina (Al ₂ O ₃ ), iron oxide (Fe2O ₃ , FeO, Fe ₃ O4), copper oxide ( CuO, Cu ₂ O), zinc oxide (ZnO), yttrium oxide (Y ₂ O ₃ ), niobium oxide (Nb ₂ O ₅ ), molybdenum oxide (MoO ₃ ), indium oxide (In ₂ O ₃ , In ₂ O) , tin oxide (SnO ₂ ), tantalum oxide (Ta ₂ O ₅ ), tungsten oxide (WO ₃ , W ₂ O ₅ ), lead oxide (PbO, PbO ₂ ), bismuth oxide (Bi ₂ O ₃ ), cerium oxide ( CeO ₂ , Ce ₂ O ₃ ), antimony oxide (Sb ₂ O ₃ , Sb ₂ O ₅ ), germanium oxide (GeO ₂ , GeO), lanthanum oxide (La ₂ O ₃ ), ruthenium oxide (RuO ₂ ), and Examples include composite oxides such as manganese (MnO), tin-doped indium oxide (ITO), antimony-doped tin oxide (ATO), and aluminum zinc oxide (ZnO.Al ₂ O ₃ ).

Examples of metal carbonates include zirconium carbonate (Zr(CO ₃ ) ₂ ), titanium carbonate (Ti(CO ₃ ) ₂ ), iron carbonate (FeCO ₃ ), copper carbonate (Cu ₂ CO ₃ ), and zinc carbonate (ZnCO ₃ ), molybdenum carbonate, cerium carbonate (CeCO ₃ ), nickel carbonate (NiCO ₃ ), cobalt carbonate (CoCO ₃ ), and manganese carbonate (MnCO ₃ ).

Examples of metal nitrates include zirconium nitrate (Zr(NO ₃ ) ₄ ), iron nitrate (Fe(NO ₃ ) ₃ ), copper nitrate (Cu(NO ₃ ) ₂ ), and titanium nitrate (Ti(NO ₃ ) ₄ ). , cerium nitrate (Ce( _NO3 ) ₃ ), nickel nitrate (Ni( _NO3 ) ₂ ), cobalt nitrate (Co( _NO3 ) ₂ ), and manganese nitrate (Mn( _NO3 ) ₂ ).

The inorganic additive is preferably silica (SiO ₂ ) from the viewpoint of improving hydrophilicity, and cerium oxide (CeO ₂ , Ce ₂ O ₃ ), manganese oxide (MnO), cerium carbonate (CeCO ₃ ) from the viewpoint of improving chemical durability. , manganese carbonate (MnCO ₃ ), cerium nitrate (Ce(NO ₃ ) ₃ ), manganese nitrate (Mn(NO ₃ ) ₂ ), and titanium nitrate (Ti(NO ₃ ) ₄ ) are preferred.

The form of the inorganic additive may be particulate, fibrous, or amorphous, but amorphous is particularly desirable.

The mass proportion of the inorganic additive in the polymer electrolyte solution is preferably 0.01 to 100 mass%, more preferably 0.01 to 45 mass%, even more preferably 0.01 to 25 mass%, Particularly preferred is 0.5 to 6.0% by mass. By containing 0.01% by mass or more of the inorganic additive, it is possible to improve chemical durability during fuel cell operation.

Polyelectrolyte solutions can be concentrated to achieve a desired solids concentration. The concentration method is not particularly limited. For example, there is a method of heating to evaporate the solvent, a method of concentrating under reduced pressure, and the like. The solid content of the resulting polymer electrolyte solution is preferably 0.5 to 50% by mass in consideration of handleability and productivity.

The polymer electrolyte solution is more preferably filtered from the viewpoint of removing coarse particle components. The filtration method is not particularly limited, and conventionally used general methods can be applied.

In addition to the fluorine-containing microporous polymer electrolyte, the polymer electrolyte solution may contain other polymer electrolytes that are not fluorine-containing microporous polymers.

式中、
Ｙ^３１は、それぞれ独立して、Ｆ、Ｃｌ、又は炭素数１～３のパーフルオロアルキル基を表す。
ｋは０～２の整数を表し、ｎは０～８の整数を表す。
Ｙ^３２は、それぞれ独立して、Ｆ又はＣｌを表す。
ｍは２～６の整数を表す。
Ｚ^３１は、Ｈ、アルカリ金属、アルカリ土類金属、又はＮＲ_４を表す。
Ｒは、それぞれ独立に、アルキル基又はＨを表す。）

式中、
Ｙ^３３は、Ｆ、Ｃｌ、又は炭素数１～３のパーフルオロアルキル基を表す。
ｏは０～１の整数を表す。
Ｑ^３１は、エーテル結合を有していてもよい炭素数１～６のパーフルオロアルキレン基である。
Ｑ^３２は、単結合又はエーテル結合を有していてもよい炭素数１～６のパーフルオロアルキレン基である。
Ｒ^３１は、エーテル結合を有していてもよいパーフルオロアルキル基である。
Ｘは、Ｏ、Ｎ、又はＣであり、ＸがＯの場合はａは０であり、ＸがＮの場合はａは１であり、ＸがＣの場合はａは２である。
Ｚ^３２は、Ｈ、アルカリ金属、アルカリ土類金属、又はＮＲ^３２ _４を表す。
Ｒ^３２は、それぞれ独立に、アルキル基又はＨを表わす。） The polymer electrolyte other than the fluorine-containing microporous polymer is not particularly limited, and known polymer electrolytes can be used. For example, there may be mentioned a polymer having a repeating unit represented by the following formula (24) or (25).

During the ceremony,
Y ³¹ each independently represents F, Cl, or a perfluoroalkyl group having 1 to 3 carbon atoms.
k represents an integer from 0 to 2, and n represents an integer from 0 to 8.
Y ³² each independently represents F or Cl.
m represents an integer from 2 to 6.
^Z31 represents H, an alkali metal, an alkaline earth metal, or _NR4 .
Each R independently represents an alkyl group or H. )

During the ceremony,
Y ³³ represents F, Cl, or a perfluoroalkyl group having 1 to 3 carbon atoms.
o represents an integer from 0 to 1.
Q ³¹ is a perfluoroalkylene group having 1 to 6 carbon atoms which may have an ether bond.
Q ³² is a perfluoroalkylene group having 1 to 6 carbon atoms which may have a single bond or an ether bond.
R ³¹ is a perfluoroalkyl group which may have an ether bond.
X is O, N, or C; when X is O, a is 0; when X is N, a is 1; when X is C, a is 2.
Z ³² represents H, an alkali metal, an alkaline earth metal, or NR ³² ₄ .
R ³² each independently represents an alkyl group or H. )

Regarding formula (24), Y ³¹ is preferably F or CF ₃ . Preferably, k is 0. It is preferable that n is 0 or 1. ^Y32 is preferably F. Preferably, m is 2. Preferably, ^Z31 is H, Na, K, or _NH4 .

Formula (24) is particularly applicable to -CF ₂ -CF(-O-CF ₂ -CF ₂ -SO ₃ H)- or -CF ₂ -CF(-O-CF ₂ -CF(CF ₃ )-O-CF ₂ -CF ₂ -SO ₃ H)- is preferred.

Regarding formula (25), Y ³³ is preferably F. It is preferable that o is 0. Q ³¹ is preferably -CF ₂ -CF ₂ - or -CF ₂ -O-CF ₂ -CF ₂ -. Q ³² is preferably -O-CF ₂ -CF ₂ -. R ³¹ is preferably -CF ₃ or -CF ₂ -CF ₃ . Preferably, X is O. Preferably, ^Z32 is H, Na, K, or _NH4 .

Formula (25) is particularly applicable to -CF ₂ -CF (-O-CF ₂ -CF (-CF ₂ -O-CF ₂ -CF ₂ -SO ₃ H) (-O-CF ₂ -CF ₂ -SO ₃ H)- is preferred.

(electrode catalyst ink)
The electrode catalyst ink of the present embodiment preferably contains the polymer electrolyte solution of the present invention and a catalyst.
The electrode catalyst ink can be suitably used as a raw material for forming an electrode catalyst layer (for example, a cathode electrode catalyst layer) of a fuel cell. The electrode catalyst ink is preferably an electrode catalyst ink for forming an electrode catalyst layer of a fuel cell.

The catalyst is not particularly limited as long as it can have activity in the electrode catalyst layer, and is appropriately selected depending on the purpose of use of the fuel cell in which the electrode catalyst layer is used. Preferably, the catalyst is a catalytic metal.

The catalyst is preferably a metal that promotes the oxidation reaction of hydrogen and the reduction reaction of oxygen, such as platinum, gold, silver, palladium, iridium, rhodium, ruthenium, iron, cobalt, nickel, chromium, tungsten, manganese, vanadium. More preferably, the metal is at least one metal selected from the group consisting of , and alloys thereof. Among these, platinum is preferred.

The particle size of the catalyst metal is not limited, but is preferably 10 to 1000 angstroms, more preferably 10 to 500 angstroms, and most preferably 15 to 100 angstroms.

The content of the polymer electrolyte in the electrode catalyst ink is preferably 5 to 30% by mass, more preferably 8% by mass or more, and preferably 10% by mass or more, based on the electrode catalyst ink. The content is more preferably 20% by mass or less, even more preferably 15% by mass or less.

The content of the catalyst in the electrode catalyst ink is preferably 50 to 200% by mass, more preferably 80% by mass or more, and even more preferably 100% by mass or more, based on the polymer electrolyte. , more preferably 150% by mass or less, and even more preferably 130% by mass or less.

Preferably, the electrode catalyst ink further contains a conductive agent. One preferable form of the catalyst and the conductive agent is that the catalyst and the conductive agent are composite particles (for example, Pt-supported carbon, etc.) made of a conductive agent supporting particles of the catalyst. In this case, the polyelectrolyte also functions as a binder.

The conductive agent is not limited as long as it has conductivity (conductive particles), but examples include carbon black such as furnace black, channel black, and acetylene black, activated carbon, graphite, and various metals (excluding catalytic metals). It is preferable that at least one type of conductive particle is selected from the group consisting of: The particle size of these conductive agents is preferably 10 angstroms to 10 μm, more preferably 50 angstroms to 1 μm, and most preferably 100 to 5000 angstroms.

In the composite particles, the content of catalyst particles relative to the conductive particles is preferably 1 to 99% by mass, more preferably 10 to 90% by mass, and most preferably 30 to 70% by mass. Specifically, preferred examples include Pt catalyst-supported carbons such as TEC10E40E, TEC10E50E, and TEC10E50HT manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.

The content of the composite particles is preferably 1.0 to 3.0% by mass, more preferably 1.4 to 2.9% by mass, even more preferably 1.7 to 2% by mass, based on the polymer electrolyte. .9% by weight, particularly preferably 1.7-2.3% by weight.

The electrocatalyst ink may further contain a water repellent. Examples of the water repellent include polytetrafluoroethylene (hereinafter referred to as PTFE) and a copolymer of tetrafluoroethylene and perfluoro(2,2-dimethyl-1,3-dioxole). The shape of the water repellent is not particularly limited, but it may be of any fixed shape, preferably particulate or fibrous, and these may be used alone or in combination.

The content of the water repellent is preferably 0.01 to 30.0% by mass, more preferably 1.0 to 25.0% by mass, even more preferably 2.0 to 25.0% by mass, based on the polymer electrolyte. 20.0% by weight, particularly preferably 5.0-10.0% by weight.

(electrode catalyst layer)
The electrode catalyst layer of this embodiment is preferably an electrode catalyst layer containing a polymer electrolyte. The electrode catalyst layer preferably contains an electrode catalyst ink, and more preferably consists of an electrode catalyst ink. The electrode catalyst layer can be manufactured at low cost and has high oxygen permeability. The electrode catalyst layer can be used as a cathode electrode catalyst layer, and can be suitably used for fuel cells.

The electrode catalyst layer preferably comprises a polymer electrolyte and a catalyst. In the electrode catalyst layer, the amount of polymer electrolyte supported relative to the electrode area is preferably 0.001 to 10 mg/cm ² , more preferably 0.01 to 5 mg/cm ² , and still more preferably 0.1 to 1 mg/cm ² It is.

The electrode catalyst layer preferably comprises a polymer electrolyte, a catalyst, and a conductive agent. In one preferred embodiment, the electrode catalyst layer is composed of a polymer electrolyte and the composite particles (eg, Pt-supported carbon, etc.). In this case, the polyelectrolyte also functions as a binder.

The conductive agent is the same as that described for the electrode catalyst ink.

In the composite particles, the catalyst particles preferably account for 1 to 99% by mass, more preferably 10 to 90% by mass, and most preferably 30 to 70% by mass relative to the conductive particles. Specifically, a suitable example is Pt catalyst-supported carbon such as TEC10E40E manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.

The content of the composite particles is preferably 20 to 95% by mass, more preferably 40 to 90% by mass, even more preferably 50 to 85% by mass, particularly preferably 60 to 85% by mass, based on the total mass of the electrode catalyst layer. It is 80% by mass.

When the electrode catalyst layer is used as an electrode catalyst layer of a fuel cell, the amount of catalyst metal supported relative to the electrode area is preferably 0.001 to 10 mg/cm ² , more preferably 0. 0.01 to 5 mg/cm ² , more preferably 0.1 to 1 mg/cm ² , even more preferably 0.2 to 0.5 mg/cm ² .

The thickness of the electrode catalyst layer is preferably 0.01 to 200 μm, more preferably 0.1 to 100 μm, and most preferably 1 to 50 μm.

The electrode catalyst layer may contain a water repellent if necessary.

The water repellent is the same as that described for the electrode catalyst ink.

When the electrode catalyst layer contains a water repellent, the content of the water repellent is preferably 0.001 to 20% by mass, more preferably 0.01 to 10% by mass, based on the total mass of the electrode catalyst layer. , most preferably 0.1 to 5% by weight.

The electrode catalyst layer may contain inorganic additives to improve hydrophilicity and chemical durability.

The inorganic additives are the same as those explained for the polymer electrolyte solution.

The content of the inorganic additive is preferably 0.001 to 20% by mass, more preferably 0.01 to 10% by mass, and most preferably 0.1 to 5% by mass, based on the total mass of the electrode catalyst layer. It is.

The method for producing an electrode catalyst layer includes, for example, a step of preparing an electrode catalyst ink by dispersing a catalyst in the obtained polymer electrolyte solution, a step of applying the electrode catalyst ink to a base material, and a step of preparing an electrode catalyst ink applied to the base material. The method includes a step of drying the catalyst ink to obtain an electrode catalyst layer.

The step of preparing an electrocatalyst ink by dispersing a catalyst in the obtained polymer electrolyte solution is to prepare an electrode catalyst ink in which composite particles are dispersed in the obtained emulsion or polymer electrolyte solution. preferable.

The electrode catalyst ink can be applied by various commonly known methods such as screen printing and spraying.

(Membrane electrode assembly)
The membrane/electrode assembly (hereinafter also referred to as "MEA") of this embodiment preferably includes an electrode catalyst layer and an electrolyte membrane. Since the membrane electrode assembly of this embodiment includes an electrode catalyst layer, it has excellent battery characteristics, mechanical strength, and stability. The membrane electrode assembly can be suitably used for fuel cells.

A unit in which two types of electrode catalyst layers, an anode and a cathode, are joined to both sides of an electrolyte membrane is called a membrane electrode assembly. An MEA in which a pair of gas diffusion layers are joined to face each other further outside the electrode catalyst layer may also be called an MEA. The electrode catalyst layer needs to have proton conductivity.

The electrode catalyst layer as an anode includes a catalyst that easily generates protons by oxidizing fuel (e.g. hydrogen), and the electrode catalyst layer as a cathode reacts protons and electrons with an oxidizing agent (e.g. oxygen or air). and a catalyst for producing water. For both the anode and the cathode, the above-mentioned catalytic metals can be suitably used as the catalyst.

As the gas diffusion layer, for example, commercially available carbon cloth, carbon paper, carbon felt, etc. can be used. These gas diffusion layers are preferably treated to be water repellent, for example, with polytetrafluoroethylene. Specific examples of the gas diffusion layer include carbon fiber trading cards (manufactured by Toray Industries, Inc.), pyrofil (manufactured by Mitsubishi Chemical Corporation), and SIGRACET GDL (manufactured by MFC Technology Corporation).

The MEA can be produced, for example, by sandwiching an electrolyte membrane between electrode catalyst layers and joining them by hot pressing. Methods for making MEAs are well known to those skilled in the art. The method for producing MEA is described, for example, in JOURNAL OF APPLIED ELECTROCHEMISTRY, 22 (1992) p. 1-7 is described in detail.

The MEA (including an MEA having a structure in which a pair of gas diffusion electrodes face each other) is further combined with components used in general fuel cells such as a bipolar plate and a backing plate to configure a fuel cell. .

A bipolar plate means, for example, a composite material of graphite and resin, a metal plate, etc., on the surface of which grooves are formed for flowing gases such as fuel and oxidizer. In addition to the function of transmitting electrons to an external load circuit, the bipolar plate also functions as a flow path for supplying fuel and oxidizer to the vicinity of the electrode catalyst. A fuel cell is manufactured by inserting a plurality of MEAs between such bipolar plates and stacking them.

(Fuel cell)
The fuel cell of this embodiment preferably includes the membrane electrode assembly described above. Preferably, the fuel cell is a polymer electrolyte fuel cell. The fuel cell is not particularly limited as long as it has a membrane electrode assembly, and may normally contain constituent components such as gas that constitute the fuel cell. Since a fuel cell includes a membrane electrode assembly having an electrode catalyst layer, it has excellent cell characteristics, mechanical strength, and stability.

Next, the present invention will be explained with reference to Examples, but these Examples are only intended to illustrate the present invention, and are not intended to limit the present invention.

(ion exchange capacity)
Approximately 2 to 20 cm ² of a polymer electrolyte membrane in which the counter ion of the ion exchange group is a proton was immersed in 30 ml of a saturated NaCl aqueous solution at 25° C. and left for 30 minutes with stirring. Next, protons in the saturated aqueous NaCl solution were neutralized and titrated using a 0.01N aqueous sodium hydroxide solution using phenolphthalein as an indicator. The polymer electrolyte membrane obtained after neutralization, in which the counter ions of the ion exchange groups were in the state of sodium ions, was rinsed with pure water, further dried in vacuum, and weighed. The amount of sodium hydroxide required for neutralization is M (mmol), the weight of the polymer electrolyte membrane in which the counter ion of the ion exchange group is sodium ion is W (mg), and the equivalent weight EW (g/eq. ) was sought.
EW=(W/M)-22

(Specific surface area)
The specific surface area determined by the BET method was used as an index of voids in the polymer electrolyte. The specific surface area was measured by a nitrogen gas adsorption method under liquid nitrogen temperature (77 K) using Belsorp Mini X manufactured by Microtrac Bell, and was calculated by analysis using the BET method.

(oxygen solubility)
With reference to Electrochimica Acta 209 (2016) 682-690, the oxygen solubility of a polymer electrolyte membrane was measured using a chronoamperometry method. Temperature and humidity were adjusted by pressing a glass-encapsulated platinum microelectrode with a diameter of 100 μm against a sample with a thickness of about 200 μm. In a nitrogen or oxygen atmosphere, the potential was held at 1100 mV (vs. SHE), then stepped to 400 mV, and the current value was measured. The difference between the current values observed under nitrogen and oxygen atmospheres was plotted against the −1/2 power of the application time, and the oxygen solubility was calculated using the following formula within the range where linearity was obtained.
I=4πFrDc[1+r/(πDt) ^1/2 +0.2732exp{-0.3911r/(Dt) ^1/2 }]
However, I is the current value (A), F is the Faraday constant (96500C/mol), r is the electrode radius (cm), D is the oxygen diffusion coefficient (cm ² /s), and c is the oxygen solubility (mol/m ³ ). , t is time (s). In this study, the oxygen solubility was shown at an evaluation temperature of 80° C. and a humidity of 30%.

(SEM observation)
The surface of the catalyst layer produced using a die coater was observed using a scanning electron microscope (product name: VE8800, manufactured by Keyence Corporation) under conditions of a magnification of 50 times and an acceleration voltage of 1 kV. As a result of the observation, cases where there were no cracks on the surface of the catalyst layer were rated "A" (good), and cases where cracks were observed were rated "B" (poor).

(Fuel cell evaluation)
In order to evaluate the performance of MEA under high temperature and low humidity conditions, a power generation test was conducted using the following procedure.

(1) Preparation of electrode catalyst ink A polymer electrolyte solution with a solid content concentration of 15% by mass, an electrode catalyst (TEC10E40E, manufactured by Tanaka Kikinzoku Kogyo Co., Ltd., platinum loading amount of 36.7wt%), and a platinum/perfluorosulfonic acid polymer. 1/1.15 (mass), then ethanol was added so that the solid content (total of the electrode catalyst and perfluorosulfonic acid polymer) was 11 wt%, and the mixture was rotated using a homogenizer (manufactured by As One). An electrode catalyst ink was obtained by stirring at 3000 rpm for 10 minutes.

(2) Preparation of electrode catalyst layer Using a die coater (product name: Rika Dai, manufactured by Itochu Fine Techno Co., Ltd.), coat it on a Teflon (registered trademark) substrate (product name: Naflon Tape, manufactured by Nichias Corporation) with a film thickness of 100 μm. The above electrode catalyst ink was applied so that the amount of platinum was 0.2 mg/cm ² , and was dried and solidified at 160° C. for 5 minutes to obtain an electrode catalyst layer.

(3) Preparation of MEA Using a press machine (product name: SFA-37, manufactured by Shinto Metal Industry Co., Ltd.), apply Nafion DE2020CS as a polymer electrolyte on both sides of an electrolyte membrane (product name: Nafion HP, manufactured by Chemours) on the anode side. An MEA was obtained by hot pressing the used electrode catalyst layer using the polymer electrolyte of this embodiment on the cathode side at a temperature of 160° C. and a pressure of 13 MPa.

(4) Production of fuel cell single cell A fuel cell single cell was obtained by layering a gas diffusion layer (product name: GDL35BC, manufactured by MFC Technology) on both poles of the MEA, and then layering a gasket, bipolar plate, and backing plate. .

(5) Power generation test A power generation test was conducted by setting the single fuel cell cell in an evaluation device (Fuel Cell Evaluation System 890CL manufactured by Toyo Technica).

The test conditions for power generation were as follows: high humidification conditions were set to a cell temperature of 65°C and anode and cathode humidification bottles of 60°C (relative humidity 80% RH), and low humidification conditions were a cell temperature of 90°C and anode and cathode humidification. The temperature of the bottle was set at 61° C. (relative humidity: 30% RH), and hydrogen gas was supplied to the anode side and air gas was supplied to the cathode side at a rate of 900 ml/min. Further, both the anode side and the cathode side were left unpressurized (atmospheric pressure).

Under the above high humidification conditions, if the voltage value is 0.830V or more at a current density of 0.2A/cm ² , it will be rated "A" (excellent), if it is more than 0.820V and less than 0.830V, it will be rated "B" (fair). If it is 0.820V or less, it is marked as "C"(poor); if the voltage value is 0.685V or more at a current density of 0.8A/ ^cm2 , it is marked as "A" (excellent), and more than 0.675V is 0.685V. If it was less than 0.675V, it was labeled as "B" (fair), and if it was 0.675V or less, it was labeled as "C" (poor).

Under the above low humidification conditions, if the voltage value is 0.750V or more at a current density of 0.2A/ ^cm2 , it will be rated "A" (excellent), and if it exceeds 0.720V and is less than 0.750V, it will be rated "B" (fair). ), if it is 0.720V or less, it is marked as "C"(poor); if the voltage value is 0.550V or more at a current density of 0.8A/ ^cm2 , it is marked as "A" (excellent), and it is more than 0.440V. If it was less than .550V, it was rated "B" (fair), and if it was 0.440V or less, it was rated "C" (poor).

(chemical durability)
A fuel cell single cell was set in the evaluation device (Toyo Technica Fuel Cell Evaluation System 890CL), the cell temperature was 90°C, the humidifier bottle was 61°C (relative humidity 30% RH), hydrogen gas was applied to the anode side, and air gas was applied to the cathode side. An OCV test was carried out by distributing the following at a rate of 300 cc/min.

In order to determine the end point of the OCV test, a micro gas chromatograph (product name: CP-4900, manufactured by GL Science) was connected to the cathode side, and the concentration of H ₂ gas permeating from the anode side was measured. The end point was when the concentration of H ₂ gas exceeded 1000 ppm. An end point of 200 hours or more was designated as "A" (good), and an end point of less than 200 hours was designated as "B" (poor).

(Example 1)
In a 100 ml three-necked flask, 7.0 g (30 mmol) of 2,3,5,6-tetrafluoro-4-(trifluoromethyl)phenol, 10 ml of 1,2-dimethoxyethane, and 0.45 g of sodium hydride ( 60%, 12 mmol), purged with nitrogen, capped, and stirred at 50° C. for 1 hour. Thereafter, 3.5 g (12 mmol) of CF ₂ =CF-OCF ₂ CF ₂ SO ₃ Na and 10 ml of 1,2-dimethoxyethane were added, and the mixture was stirred at 95° C. for 6 hours. After the reaction was completed, the solvent was removed using an evaporator, ethyl acetate and brine were added to the remaining solid, and liquid separation extraction and solvent distillation were performed. Thereafter, purification was performed by column chromatography, and after distilling off the solvent, 4.0 g (yield 65%) of an aromatic monomer (M1) having a sodium sulfonate group represented by formula (26) was obtained. In ¹⁹ F-NMR, integral ratio 3 at -58 ppm, integral ratio 1 at -84 ppm, integral ratio 1 at -86 ppm, integral ratio 2 at -89 ppm, integral ratio 2 at -119 ppm, integral ratio 2 at -141 ppm, - A peak with an integral ratio of 1 was observed at 146 ppm, and a peak with an integral ratio of 2 was observed at -155 ppm. In ¹ H-NMR, a peak with an integral ratio of 1 was observed at 6.5 to 6.8 ppm.

Subsequently, condensation was performed using monomer (M1) and 3,3,3',3'-tetramethyl-1,1'-spirobiindane-5,5',6,6'-tetraol (monomer (M2)). Polymerization was performed. In a 100 ml three-necked flask, 4.0 g (7.5 mmol) of monomer (M1), 2.5 g (7.5 mol) of monomer (M2), 2.1 g (15 mmol) of potassium carbonate, and N,N-dimethylformamide. After adding 50 ml of the flask, purging with nitrogen and capping the flask, the flask was stirred at 150° C. for 48 hours. After the polymerization was completed, it was allowed to cool, and the reaction solution was poured into ion-exchanged water, filtered under reduced pressure through a glass filter, thoroughly washed with ion-exchanged water, and dried at 100° C. for 12 hours. A fluorine-containing microporous polymer electrolyte (A1) having an SO ₃ Na group was obtained in a yield of 4.2 g (yield 70%).

Furthermore, the polymer electrolyte (A1) was ion-exchanged as follows. 4.2 g of polymer electrolyte (A1) and 100 ml of 4N hydrochloric acid aqueous solution were added to a 250 ml PP bottle, and the mixture was stirred at 60° C. for 2 hours. Thereafter, the supernatant liquid was removed by decantation. This ion exchange operation was repeated four times. Thereafter, it was filtered under reduced pressure using a glass filter, thoroughly washed with ion-exchanged water, and dried at 100° C. for 12 hours. A fluorine-containing microporous polymer electrolyte (A2) having a sulfonic acid group represented by formula (27) was obtained in a yield of 3.7 g (yield 88%). In ^19F -NMR, there are peaks with an integral ratio of 3 at -57 to -60 ppm, a peak at an integral ratio of 4 at -83 to -92 ppm, a peak at an integral ratio of 2 at -118 to -121 ppm, and a peak at an integral ratio of 1 at -145 to -148 ppm. It was seen. In ¹ H-NMR, peaks were observed at an integral ratio of 12 at 0.8-1.7 ppm, at an integral ratio of 4 at 1.9--2.5 ppm, and at an integral ratio of 5 at 5.7-7.3 ppm.

The obtained polymer electrolyte (A2) was placed in a 100 mL autoclave together with ethanol, the autoclave was sealed, and the autoclave was purged with nitrogen.The autoclave was then heated to 160° C. while being stirred with a stirring blade and held for 6 hours. Thereafter, the autoclave was naturally cooled to prepare a uniform polymer solution with a solid content concentration of 10% by mass. The obtained polymer solution with a solid content concentration of 10% by mass was concentrated under reduced pressure at 80° C. to produce a polymer electrolyte solution with a solid content concentration of 15% by mass.

The polymer electrolyte solution was poured into a petri dish, dried at 80° C. for 30 minutes, then at 120° C. for 30 minutes, and then heat-treated at 160° C. for 15 minutes, thereby producing a 200 μm thick film. Table 1 shows the specific surface area, membrane EW, and oxygen solubility of the polymer electrolyte (A2). Further, using the polymer electrolyte solution, an electrode catalyst ink, an electrode catalyst layer, an MEA, and a fuel cell single cell were prepared according to the methods described in (1) to (4) of "Fuel Cell Evaluation" above, and the electrode catalyst layer was The presence or absence of cracks, battery performance, and chemical durability were evaluated. The results are shown in Table 1.

The specific surface area of the polymer electrolyte (A2) is large, and the membrane exhibits high oxygen solubility. Furthermore, there were no cracks in the electrode catalyst layer containing the polymer electrolyte solution, indicating that the battery performance and chemical durability were higher than the comparative example materials.

(Example 2)
In a 100 ml three-neck flask, 4.1 g (12 mol) of 3,3,3',3'-tetramethyl-1,1'-spirobiindane-5,5',6,6'-tetraol (monomer M4), 1.7 g (12 mmol) of potassium carbonate and 25 ml of N,N-dimethylformamide were added, the atmosphere was purged with nitrogen, the mixture was capped, and the mixture was stirred at 100° C. for 30 minutes. Thereafter, 4.0 g (12 mol) of decafluorobiphenyl (monomer M3) and 115 ml of N,N-dimethylformamide were slowly dropped into the three-necked flask. After the dropwise addition was completed, the mixture was stirred at 100°C for 24 hours. Thereafter, it was allowed to cool, and reprecipitation was performed three times with methanol and chloroform. After vacuum filtration with a glass filter, it was thoroughly washed with ion-exchanged water and dried at 100° C. for 12 hours. A fluorine-containing microporous polymer (P1) represented by formula (28) was obtained in an amount of 5.2 g (yield 73%). In ¹⁹ F-NMR, peaks of integral ratio 2 were observed at -138 to -141 ppm, at -142 to -145 ppm, and at -163 to 166 ppm, respectively. In ^1H -NMR, peaks with an integral ratio of 12 were observed at 1.0-1.8 ppm, a peak with an integral ratio of 4 between 1.9 and -2.5 ppm, and a peak with an integral ratio of 4 at 6.3-6.9 ppm. . GPC showed that the weight average molecular weight was 20,000 and the molecular weight distribution was 5.

Next, OW groups were introduced into the polymer (P1) as follows. In a 200 ml three-necked flask, put 5 g of polymer (P1), 0.8 g (14 mmol) of potassium hydroxide, 3.8 g (14 mmol) of 18-crown-6, 5 ml of water, and 90 ml of 1,4-dioxane. After purging with nitrogen and capping the reactor, the reactor was stirred at 100° C. for 6 hours. The reaction solution was poured into ion-exchanged water, filtered under reduced pressure through a glass filter, thoroughly washed with ion-exchanged water, and dried at 100° C. for 12 hours. A fluorine-containing microporous polymer (P2) having an OW group represented by formula (29) was obtained in an amount of 3.7 g (yield 70%). NMR of the polymer (P2) revealed that one of the six fluorine atoms directly bonded to the aromatic group in the repeating unit of formula (28) was converted to an OW group. (Formula (29))

Next, 3.5 g of polymer (P2), 0.21 g (60%, 5.7 mmol) of sodium hydride, and 30 ml of 1,4-dioxane were placed in a 200 ml three-necked flask, the atmosphere was replaced with nitrogen, and the cap was capped. After that, the mixture was stirred at 50°C for 1 hour. Then, 8.0 g (27 mmol) of CF ₂ =CF-OCF ₂ CF ₂ SO ₃ Na, 1.2 g (5.4 mmol) of 15-crown-5, and 40 ml of 1,4-dioxane were added, and the mixture was heated at 100°C for 24 hours. Stirred. Thereafter, the reaction solution was poured into ion-exchanged water, filtered under reduced pressure through a glass filter, thoroughly washed with ion-exchanged water, and dried at 100° C. for 12 hours. A fluorine-containing microporous polymer electrolyte having an SO ₃ Na group represented by formula (30) was obtained in a yield of 3.2 g (yield 66%).

Furthermore, ion exchange of the polymer electrolyte was performed as follows. 3.2 g of polymer electrolyte and 100 ml of 4N hydrochloric acid aqueous solution were added to a 250 ml PP bottle, and the mixture was stirred at 60° C. for 2 hours. Thereafter, the supernatant liquid was removed by decantation. The same operation as described above was repeated four times. Thereafter, it was filtered under reduced pressure using a glass filter, thoroughly washed with ion-exchanged water, and dried at 100° C. for 12 hours. A fluorine-containing microporous polymer electrolyte having a sulfonic acid group represented by formula (31) was obtained in a yield of 2.9 g (yield 90%). NMR of the polymer electrolyte of formula (31) revealed that a compound having a sulfonic acid group was added to the OW group in the repeating unit of formula (29). In ^19F -NMR, peaks with an integral ratio of 4 were observed at -85 to -94 ppm, at an integral ratio of 2 between -120 and -123 ppm, at an integral ratio of 4 between -140 and -151 ppm, and at an integral ratio of 2 between -165 and 171 ppm. It was done. In ¹ H-NMR, peaks were observed at an integral ratio of 12 at 0.7-1.6 ppm, at an integral ratio of 4 at 1.9--2.5 ppm, and at an integral ratio of 5 at 5.8-7.4 ppm.

The obtained polymer electrolyte of formula (31) was converted into a solution in the same manner as in Example 1 to obtain a polymer electrolyte solution with a solid content concentration of 15% by mass. A membrane with a thickness of 200 μm was produced using the polymer electrolyte solution by the method described above. Table 1 shows the specific surface area, membrane EW, and oxygen solubility of the polymer electrolyte of formula (31). In addition, using the polymer electrolyte solution, an electrode catalyst ink, an electrode catalyst layer, an MEA, and a fuel cell single cell were prepared in the same manner as in Example 1, and the presence or absence of cracks in the electrode catalyst layer, battery performance, and chemical durability were determined. evaluated. The results are shown in Table 1.

The specific surface area of the polymer electrolyte of formula (31) is large, and the membrane exhibits high oxygen solubility. Furthermore, there were no cracks in the electrode catalyst layer containing the polymer electrolyte solution, indicating that the battery performance and chemical durability were higher than the comparative example materials.

(Example 3)
Instead of 3,3,3',3'-tetramethyl-1,1'-spirobiindane-5,5',6,6'-tetraol (monomer M4), 2,2',3,3'- A fluorine-containing microporous polymer electrolyte having a sulfonic acid group represented by formula (32) was obtained in the same manner as in Example 2, except that tetrahydroxy-1,1'-binaphthyl was used. In ^19F -NMR, peaks with an integral ratio of 4 were observed at -84 to -93 ppm, at an integral ratio of 2 between -119 and -122 ppm, at an integral ratio of 4 between -140 and -151 ppm, and at an integral ratio of 2 between -165 and 171 ppm. It was done. In ¹ H-NMR, peaks with an integral ratio of 11 were observed at 5.7-7.8 ppm.

The polymer electrolyte was converted into a solution in the same manner as in Example 1 to obtain a polymer electrolyte solution with a solid content concentration of 15% by mass. A membrane with a thickness of 200 μm was produced using the polymer electrolyte solution by the method described above. Table 1 shows the specific surface area of the polymer electrolyte, the EW of the membrane, and the oxygen solubility. In addition, using the polymer electrolyte solution, an electrode catalyst ink, an electrode catalyst layer, an MEA, and a fuel cell single cell were prepared in the same manner as in Example 1, and the presence or absence of cracks in the electrode catalyst layer, battery performance, and chemical durability were determined. evaluated. The results are shown in Table 1.

The specific surface area of the polymer electrolyte is large, and the membrane exhibits high oxygen solubility. Furthermore, there were no cracks in the electrode catalyst layer containing the polymer electrolyte solution, indicating that the battery performance and chemical durability were higher than the comparative example materials.

(Comparative example 1)
Using a commercially available Nafion solution (Nafion DE2020CS, manufactured by SIGMA-ALDRICH), a cast film with a thickness of 200 μm was formed in the same manner as in Example 1, and the EW, specific surface area, and oxygen solubility were measured. The results are shown in Table 1.

Further, an electrode catalyst ink, an electrode catalyst layer, an MEA, and a single fuel cell were prepared using the Nafion solution in the same manner as in Example 1, and the presence or absence of cracks in the electrode catalyst layer, battery performance, and chemical durability were evaluated. The results are shown in Table 1.

Nafion DE2020CS has a small specific surface area and low oxygen solubility. In addition, cracks occur in the electrode catalyst layer, resulting in poor battery performance and chemical durability.

(Comparative example 2)
Copolymer of perfluoro(2,2-dimethyl-1,3-dioxole) and CF ₂ =CFOCF ₂ CF (CF ₃ )OCF ₂ CF ₂ SO ₂ F obtained by radical polymerization method (69.8 mol) %/30.2 mol%) as a polymer precursor, was brought into contact with an aqueous solution containing potassium hydroxide (15% by mass) at 70°C for 10 hours, immersed in 70°C water for 5 hours, and then exposed to 2N hydrochloric acid at 70°C. After repeating the treatment of immersion in an aqueous solution for 1 hour four times, washing with ion-exchanged water and drying, perfluoro(2,2-dimethyl-1,3-dioxole)/CF ₂ =CFOCF ₂ CF (CF ₃ ) A polymer electrolyte made of OCF ₂ CF ₂ SO ₃ H (perfluorosulfonic acid resin) was obtained. A perfluorosulfonic acid resin solution and a cast film with a thickness of 200 μm were prepared in the same manner as in Example 1. Table 1 shows the specific surface area of the perfluorosulfonic acid resin, the EW of the cast film, and the oxygen solubility.

Furthermore, in the same manner as in Example 1, an electrode catalyst ink, an electrode catalyst layer, an MEA, and a single fuel cell were prepared using the perfluorosulfonic acid resin solution, and the presence or absence of cracks in the electrode catalyst layer, battery performance, and chemical durability were evaluated. did. The results are shown in Table 1.

Since the perfluorosulfonic acid resin has a lower specific surface area and a lower oxygen solubility than the examples, the battery performance is also not sufficient. In addition, cracks have occurred in the electrode catalyst layer, resulting in a decrease in chemical durability.

Claims (15)

A fluorine-containing microporous polymer having a proton-conducting group,
The fluorine-containing microporous polymer contains a repeating unit represented by the following formula (3),
During the ceremony,
Ar ¹ represents any one structure represented below;
Ar ² represents any one structure represented below;
R ¹ each independently represents hydrogen, a halogen group, or a substituted or unsubstituted alkyl group;
m is 0 or 1;
x is 0<x≦6, y is 0≦y<6, and x+y≦6;
A represents the following structure;
Z represents H, Cl, F, or a perfluoroalkyl group having 1 to 3 carbon atoms;
p represents 0 or 1, q represents an integer from 0 to 2, r represents an integer from 0 to 12, provided that q and r are not 0 at the same time;
* is a polymer electrolyte characterized by representing a bond . The polymer electrolyte according to claim 1 , wherein the Ar ² has a structure represented by any one of the following formulas (4) to (8).
During the ceremony,
x is 0<x≦6, y is 0≦y<6, and x+y≦6. The polymer electrolyte according to claim 1 or 2 , which has a specific surface area of 250 to 6000 m ² /g as determined by the BET method. A polymer electrolyte solution comprising the fluorine-containing microporous polymer electrolyte according to any one of claims 1 to 3 and at least one selected from the group consisting of water and an organic solvent. . An electrode catalyst ink comprising the polymer electrolyte solution according to claim 4 and a catalyst. An electrocatalyst layer comprising the electrocatalyst ink according to claim 5 . A membrane electrode assembly comprising the electrode catalyst layer according to claim 6 and an electrolyte membrane. A fuel cell comprising the membrane electrode assembly according to claim 7 . A fluorine-containing microporous material obtained by condensation polymerization of a fluorine-containing aromatic monomer (M3) and an aromatic monomer (M4) and having an aromatic group and one or more fluorine atoms directly bonded to the aromatic group. A step of forming a polymer (P1);
(i) An SO ₃ X group is introduced into the fluorine-containing microporous polymer (P1) using a compound having an SO _{3 3.} Obtaining a fluorine-containing microporous polymer having an X group;
(ii) converting the SO ₃ X group of the fluorine-containing microporous polymer having the SO ₃ X group into a sulfonic acid group;
including;
The fluorine-containing aromatic monomer (M3) is any of the monomers represented by the following formula (17),
The aromatic monomer (M4) is any of the monomers represented by the following formula (14),
The compound having the SO ₃ X group has a structure represented by the following formula (9),
During the ceremony,
Z represents H, Cl, F, or a perfluoroalkyl group having 1 to 3 carbon atoms;
q represents an integer of 0 to 2, r represents an integer of 0 to 12, provided that q and r are not 0 at the same time; A method for producing a microporous polymer electrolyte. The step (i) is
(iii) An OW group (in the formula, W is hydrogen or an alkali metal ) is introduced into the fluorine-containing microporous polymer (P1) to produce a fluorine-containing microporous polymer having an OW group. The process of obtaining
(iv) reacting the fluorine-containing microporous polymer having the OW group with the compound having the SO ₃ X group to obtain the fluorine-containing microporous polymer having the SO ₃ X group;
The method for producing a polymer electrolyte according to claim 9 , comprising: The method for producing a polymer electrolyte according to claim 9 or 10 , wherein the step (ii) includes (v) ion-exchanging X of the SO ₃ X group to hydrogen. The method for producing a polymer electrolyte according to any one of claims 9 to 11 , wherein the compound having an SO ₃ X group has a structure represented by the following formula (11).
During the ceremony,
X is an alkali metal . (a) an aromatic group, four or more halogen atoms bonded to a carbon atom of the aromatic group, an SO ₃ X group (X is an alkali metal ), and one or more fluorine atoms; a step of preparing an aromatic monomer (M1) having an aromatic group and an aromatic monomer (M2) having an aromatic group and four or more hydroxyl groups bonded to a carbon atom of the aromatic group;
(b) Condensation polymerization of the halogen atom of the aromatic monomer (M1) and the hydroxyl group of the aromatic monomer (M2) in the presence of a catalyst to obtain a fluorine-containing microporous polymer having an SO ₃ X group process and
(c) converting the SO ₃ X group of the fluorine-containing microporous polymer having the SO ₃ X group into a sulfonic acid group;
including;
The aromatic monomer (M1) has any one structure represented by the following (12),
During the ceremony,
R ¹ each independently represents hydrogen, a halogen group, or a substituted or unsubstituted alkyl group;
m is 0 or 1;
B represents the following structure;
Z represents H, Cl, F, or a perfluoroalkyl group having 1 to 3 carbon atoms;
p represents 0 or 1, q represents an integer from 0 to 2, r represents an integer from 0 to 12, provided that q and r are not 0 at the same time;
X is an alkali metal;
* represents a bond,
The aromatic monomer (M2) has any one structure represented by the following (14),
A method for producing a fluorine-containing microporous polymer electrolyte having a sulfonic acid group, characterized in that: 14. The method for producing a polymer electrolyte according to claim 13 , wherein the step (c) includes (d) ion-exchanging X of the SO ₃ X group to hydrogen. The method for producing a polymer electrolyte according to claim 13 or 14 , wherein the aromatic monomer (M1) has any one structure represented by the following (13).
During the ceremony,
X is an alkali metal .