JP2021061219A - Fluorine-containing polyelectrolyte - Google Patents

Abstract

To provide a fluorine-containing polyelectrolyte which can suppress an electrode catalyst layer from cracking, which has a high in oxygen permeability, and which enables the achievement of a satisfactory power generation performance and durability in a battery in consideration of the forementioned actual state.SOLUTION: A fluorine-containing polyelectrolyte according to the present invention has, in a side chain, a sulfonyl group as a coupling group, and/or an ether bond not included in a ring structure. At least one of the sulfonyl group and the ether bond not included in the ring structure is directly bonded with at least one cyclic structure selected from a group consisting of an aromatic ring, an aliphatic ring, and a composite ring including an aromatic ring and an aliphatic ring. The cyclic structure thus directly bonded includes a nitrogen atom and/or an ethereal oxygen atom.SELECTED DRAWING: None

Description

The present invention comprises a fluorine-containing polymer electrolyte, a fluorine-containing polymer electrolyte-containing composition containing the fluorine-containing polymer electrolyte, an electrode catalyst layer containing the fluorine-containing polymer electrolyte-containing composition, and a membrane electrode including the electrode catalyst layer. The present invention relates to a assembly and a fuel cell including the membrane electrode assembly.

In recent years, polymer electrolyte fuel cells have been installed in household fuel cell systems and fuel cell vehicles and put on the market, and growth is expected in the future from the viewpoint of preventing global warming.
This polymer electrolyte fuel cell is provided with a membrane electrode assembly (MEA) in which an electrolyte membrane such as perfluorocarbon sulfonic acid and an electrode catalyst layer made of platinum-supported carbon and a binder resin (ionomer) are adhered to both sides thereof. ing.
When the hydrogen gas humidified in one electrode catalyst layer of the MEA is passed through the oxygen gas humidified in the other electrode catalyst layer, protons are generated on the electrode catalyst on the hydrogen gas side (hereinafter referred to as the anode), and the electrolyte is generated. It moves to the oxygen gas side (hereinafter referred to as the cathode) through the membrane. On the contrary, oxygen is reduced on the electrode catalyst of the cathode, and the electrons flowing from another circuit react with the protons flowing from the anode to generate water.

In the polymer electrolyte fuel cell, in particular, how to efficiently cause the oxygen reduction reaction on the electrode catalyst of the cathode is an issue.
On the other hand, in order to further market growth of polymer electrolyte fuel cell systems in the future, it is necessary to reduce the cost of various components constituting the system, but in particular, the amount of platinum catalyst used, which has a high cost ratio, will be reduced. It is necessary.
In the conventional polymer electrolyte fuel cell system, the performance was guaranteed by using many platinum catalysts for the cathode, but if the amount of platinum catalyst used is reduced, the power generation performance will be improved due to the decrease in the catalyst surface area that contributes to power generation. The problem of lowering arises.
Therefore, attempts have been made to improve the oxygen permeability of ionomers in order to supply more oxygen to a smaller catalyst surface so that oxygen can be distributed throughout the electrode.

Patent Documents 1 and 2 describe fluorine-containing polymers that have high oxygen permeability and are suitable as a fluorine-containing polymer electrolyte for the cathode side catalyst layer, and which provide a polymer having an aliphatic ring structure in the main chain by radical polymerization. A copolymer containing a repeating unit based on a monomer and a repeating unit based on a fluorosulfonic acid-containing monomer, and a gas diffusion electrode containing the copolymer are described.

Patent Document 3 describes perfluoro (1,3-dioxol) having a perfluoro ring structure at the 2-position as a fluorine-containing polymer electrolyte that has a bulky ring structure to reduce the density and promote oxygen permeability. Copolymers of perfluorovinyl ethers with sulfonic acids have been described.

Patent Document 4 describes an electrolyte having a perfluoroaliphatic compound and a sulfonimide in the main chain or side chain as a fluorine-containing polymer electrolyte having both proton conductivity and oxygen permeability.

Japanese Unexamined Patent Publication No. 2003-36859 JP-A-2002-260705 JP-A-2018-39937 Japanese Unexamined Patent Publication No. 2012-38515

However, the fluorine-containing polymer electrolytes disclosed in Patent Documents 1 to 4 have an effect of a bulky ring structure, and although the oxygen permeability increases when the blending amount is increased, when an electrode catalyst layer is formed, the surface becomes surfaced. There have been problems such as cracks, reduced power generation performance, and reduced battery durability.

Therefore, in view of the above situation, it is an object of the present invention to provide a fluorine-containing polymer electrolyte that suppresses cracking of the electrode catalyst layer, has high oxygen permeability, and has good power generation performance and durability in a battery. ..

As a result of diligent studies to solve the above problems, the present inventors have a sulfonyl group as a linking group and / or an ether bond not included in the ring structure in the side chain, and the sulfonyl group and the ring structure have an ether bond. At least one of the above ether bonds not included is directly bonded to at least one cyclic structure selected from the group consisting of an aromatic ring, an aliphatic ring, and a composite ring containing an aromatic ring and an aliphatic ring. The cyclic structure having a direct bond contains a nitrogen atom and / or an ethereal oxygen atom, so that the surface of the electrode catalyst layer is not cracked due to the fluoropolymer electrolyte, and the power generation performance and durability of the battery are not generated. We have found that the value is high, and have completed the present invention.

（式中、ＮＲ₁は窒素原子を含むパーフルオロ環構造を表す。ＮＲ₁は窒素原子を含め炭素数３〜１２の環構造であり、炭素数１〜３の置換基を有していてよく、該置換基は酸素原子を含んでも良い。上記ＮＲ₁はパーフルオロ環構造に、酸素原子、窒素原子を含んでも良い。）
［６］
［１］〜［５］のいずれかに記載の含フッ素高分子電解質と溶媒と触媒とを含むことを特徴とする、含フッ素高分子電解質含有組成物。
［７］
［６］に記載の含フッ素高分子電解質含有組成物を含むことを特徴とする、電極触媒層。
［８］
［７］に記載の電極触媒層と電解質膜とを備えることを特徴とする、膜電極接合体。
［９］
［８］に記載の膜電極接合体を備えることを特徴とする、燃料電池。 That is, the present invention is as follows.
[1]
The side chain has a sulfonyl group as a linking group and / or an ether bond not contained in the ring structure.
At least one of the sulfonyl group and the above ether bond not included in the ring structure is selected from the group consisting of an aromatic ring, an aliphatic ring, and a complex ring containing an aromatic ring and an aliphatic ring. Is directly connected to
A fluorine-containing polymer electrolyte characterized in that the cyclic structure having a direct bond contains a nitrogen atom and / or an ethereal oxygen atom.
[2]
The fluorine-containing polymer electrolyte according to [1], wherein the sulfonyl group is directly bonded to the nitrogen atom contained in the cyclic structure.
[3]
The fluorine-containing polymer electrolyte according to [1] or [2], wherein the cyclic structure having a direct bond has a substituent containing an ether bond.
[4]
The fluorine-containing polymer electrolyte according to [3], wherein the substituent containing the ether bond is a cyclic ether.
[5]
The fluorine-containing polymer electrolyte according to any one of [1] to [4], which has the structure described in the following formula (1) in the side chain.

(Wherein, NR ₁ is .NR ₁ representing the perfluoro cyclic structure containing a nitrogen atom is a ring structure having 3 to 12 carbon atoms including a nitrogen atom, may have a substituent having 1 to 3 carbon atoms , The substituent may contain an oxygen atom. The above NR ₁ may contain an oxygen atom and a nitrogen atom in the perfluoro ring structure.)
[6]
A fluorinated polymer electrolyte-containing composition comprising the fluorinated polymer electrolyte according to any one of [1] to [5], a solvent, and a catalyst.
[7]
An electrode catalyst layer comprising the fluorine-containing polymer electrolyte-containing composition according to [6].
[8]
A membrane electrode assembly comprising the electrode catalyst layer and an electrolyte membrane according to [7].
[9]
A fuel cell comprising the membrane electrode assembly according to [8].

The fluorine-containing polymer electrolyte of the present invention suppresses cracking of the electrode catalyst layer, has high oxygen permeability, and has good power generation performance and durability in a battery. The fluorine-containing polymer electrolyte-containing composition of the present invention can prevent cracking of the electrode catalyst layer. Further, the membrane electrode assembly and the fuel cell of the present invention exhibit high power generation performance and durability.

Hereinafter, the present invention will be specifically described.

[Fluorine-containing polymer electrolyte]
The fluorine-containing polymer electrolyte of the present embodiment has a sulfonyl group as a linking group and / or an ether bond not contained in the ring structure in the side chain, and at least the above ether bond not contained in the sulfonyl group and the ring structure. One is directly bonded to at least one cyclic structure selected from the group consisting of an aromatic ring, an aliphatic ring, and a composite ring including an aromatic ring and an aliphatic ring, and the above-mentioned direct bonding is performed. The cyclic structure contains nitrogen atoms and / or etheric oxygen atoms.
According to the fluorine-containing polymer electrolyte of the present embodiment, not only high oxygen permeability is exhibited, but also cracks are reduced on the surface of the electrode catalyst layer, and high performance and high chemical durability are exhibited in the operation of the fuel cell. can do.

The fluorine-containing polymer electrolyte of the present embodiment is a polymer having at least a structural unit (repeating unit) in which the side chain is bonded to the main chain (sometimes referred to as “structural unit A” in the present specification). Is preferable. The structural unit A may be one type or a plurality of types, but is preferably one type from the viewpoint of productivity.
The fluorine-containing polymer electrolyte of the present embodiment may have other structural units. The other structural unit may be one kind or a plurality of kinds.

(Structural unit A)
Hereinafter, the structural unit A will be described.
The side chain of the structural unit A contains a sulfonyl group and / or an ether bond not included in the ring structure as a linking group.
In the side chain of the structural unit A, as a linking group, a thioether group, a ketone group, an ester group, an imide group, and a carbon-carbon bond (for example, partially or completely fluorinated) which are not contained in the ring structure are further fluorinated. It may contain carbon-carbon bonds having 1 to 10 carbon atoms), and the like.
Among them, the above-mentioned linking group includes a sulfonyl group and / or an ether group not contained in the ring structure and a carbon-carbon bond from the viewpoint of solubilizing a fluorine-containing polymer electrolyte and improving chemical durability in fuel cell operation. Is preferable, and only the sulfonyl group and / or the ether group not contained in the ring structure is more preferable from the viewpoint of easiness of synthesis.

The structural unit A has a cyclic structure selected from the group consisting of an aromatic ring, an aliphatic ring, and a complex ring containing an aromatic ring and an aliphatic ring in the side chain. The cyclic structure included in the structural unit A may be one or a plurality.
The cyclic structure preferably contains a nitrogen atom and / or an etheric oxygen atom as an element constituting the ring structure, and from the viewpoint of further suppressing cracking of the electrode catalyst layer and further improving oxygen permeability, the nitrogen atom. And preferably contain an ethereal oxygen atom.
From the viewpoint of further improving oxygen permeability, the cyclic structure preferably has a substituent containing an ether bond, and preferably contains a cyclic ether.

（式３〜２８中、Ｒ₁〜Ｒ₂₆のうち少なくとも１つは上記連結基（好ましくはスルホニル基又は環構造に含まれないエーテル結合）と直接結合している。Ｒ₁〜Ｒ₂₆のうち、上記連結基と結合する置換基を除く置換基は、それぞれ独立に、フッ素原子、水素原子、アリール基、スルホン酸基、ホスホン酸基、カルボキシル基、ビススルホニルイミド基、スルホンイミド基等のイオン伝導基等で置換されていてもよい炭素数１〜１０の炭化水素基、スルホン酸基、ホスホン酸基、カルボキシル基、ビススルホニルイミド基、スルホンイミド基等のイオン伝導基等で置換されていてもよい炭素数が１〜１０のフッ素化炭化水素基、スルホン酸基、ホスホン酸基、カルボキシル基、ビススルホニルイミド基、スルホンイミド基、又はこれらの組み合わせを表す。）
上記環構造の置換基（例えば、Ｒ₁〜Ｒ₂₆）としては、酸素溶解度及び酸素透過性の向上、電極のひび割れ防止による電池性能及び化学耐久性向上の観点から、フッ素原子、炭素数が１〜１０のフッ素化炭化水素基が好ましい。
上記環状構造としては、式１３、式１４、式２５で表される構造が好ましく、酸素透過性に一層優れる観点から、式１３がより好ましい。 The annular structure is not limited to the following, and examples thereof include structures represented by the following formulas 3 to 28.

(In the formula 3 to 28, of the .R ₁ to R ₂₆ and at least one of the linking group (preferably bonded directly sulfonyl group or an ether is not included in the ring structure bonded) of R ₁ to R ₂₆ , The substituents other than the substituents bonded to the above-mentioned linking groups are independently ions such as a fluorine atom, a hydrogen atom, an aryl group, a sulfonic acid group, a phosphonic acid group, a carboxyl group, a bissulfonylimide group and a sulfonimide group. It may be substituted with a conductive group or the like, and is substituted with an ionic conductive group such as a hydrocarbon group having 1 to 10 carbon atoms, a sulfonic acid group, a phosphonic acid group, a carboxyl group, a bissulfonylimide group or a sulfonimide group. It represents a fluorinated hydrocarbon group having 1 to 10 carbon atoms, a sulfonic acid group, a phosphonic acid group, a carboxyl group, a bissulfonylimide group, a sulfonimide group, or a combination thereof.)
As the substituent of the ring structure (for example, R _{1 to} R ₂₆ ), the fluorine atom and the number of carbon atoms are 1 from the viewpoint of improving oxygen solubility and oxygen permeability, and improving battery performance and chemical durability by preventing cracking of the electrode. A fluorinated hydrocarbon group of 10 to 10 is preferable.
As the annular structure, the structures represented by the formulas 13, 14 and 25 are preferable, and the formula 13 is more preferable from the viewpoint of further excellent oxygen permeability.

The structural unit A preferably contains, in the side chain, a structure in which at least one of the cyclic structures is directly bonded to a sulfonyl group as a linking group or an ether bond not included in the ring structure, and the cyclic structure. It is more preferable that the side chain contains a structure in which the nitrogen atom contained in the above and the sulfonyl group are directly bonded.

式（１）中、ＮＲ₁は窒素原子を含むパーフルオロ環構造を表す。ＮＲ₁は、窒素原子を含め炭素数３〜１２の環構造であり、炭素数１〜３の置換基を有していてよく、上記置換基は酸素原子を含んでも良い。上記ＮＲ₁はパーフルオロ環構造を構成する原子として、酸素原子、スルホニル基と直接結合している窒素原子以外の窒素原子を含んでも良い。 The structural unit A preferably has a structure represented by the following formula (1).

In formula (1), NR ₁ represents a perfluoro ring structure containing a nitrogen atom. NR ₁ has a ring structure having 3 to 12 carbon atoms including a nitrogen atom, and may have a substituent having 1 to 3 carbon atoms, and the substituent may contain an oxygen atom. The NR ₁ may contain a nitrogen atom other than the nitrogen atom directly bonded to the oxygen atom and the sulfonyl group as an atom constituting the perfluoro ring structure.

Examples of the structure represented by the above formula (1) include structures including the above formulas 3 to 14 and formulas 23 to 28, and specifically, the structures of the following formulas 29 to 34 are preferable.

The aromatic ring contained in the side chain of the structural unit A may be substituted, an aromatic hydrocarbon ring such as benzene, naphthalene, anthracene, fluorene, helicene, pyrene; or optionally substituted, furan. , Pyran, dioxine, dibenzodioxin, pyrrole, imidazole, triazole, pyridine, pyrimidine, aromatic heterocycles such as pyrazine; and the like.
The aromatic ring preferably contains a substituent.
Here, the above-mentioned substituent means a substituent other than the above-mentioned linking group.
The above-mentioned substituent is not limited to the following, and may be substituted including, for example, a halogen atom such as a fluorine atom, an oxygen atom, a sulfonic acid group, a fluorinated hydrocarbon group, a sulfonamide group, and an ether bond. Examples thereof include a fluorinated hydrocarbon group having 1 or more carbon atoms, and among them, a fluorinated hydrocarbon group having 1 or more carbon atoms which may be substituted and contains a fluorine atom, a fluorinated hydrocarbon group and an ether bond is preferable.
By containing a fluorinated hydrocarbon group having 1 or more carbon atoms which may be substituted, which contains a fluorine atom, a fluorinated hydrocarbon group, and an ether bond, oxygen solubility is further improved, and low humidification in fuel cell operation is performed. It leads to the development of high power generation performance under both conditions of high humidification and high humidification.

The side chain has the above-mentioned linking group (preferably a sulfonyl group and / or an ether bond not contained in the ring structure) on the main chain side from the viewpoint of further excellent oxygen permeability and further suppressing cracking of the electrode catalyst layer. It is preferable to have the above-mentioned cyclic structure on the terminal side of the side chain.

The side chain may have the annular structure located at the end of the side chain or in the middle of the side chain. For example, a proton conductive group such as a hydrocarbon group or a sulfonic acid group may be arranged on the side chain terminal side of the cyclic structure, and the linking group, the cyclic structure, or the proton conductive group is arranged from the main chain side to the side chain terminal. It may be a side chain arranged in the order of groups.
From the viewpoint of further excellent oxygen permeability and further suppressing cracking of the electrode catalyst layer, the side chain has an ether bond not included in the ring structure bonded to the main chain, and the ether bond has 1 to 10 carbon atoms (preferably). Is preferably a structure in which a fluorinated hydrocarbon group having 3 to 5 carbon atoms is bonded, a sulfonyl group is bonded to the fluorinated hydrocarbon group, and the cyclic structure is bonded to the sulfonyl group.

As the side chain, the following structure is preferable from the viewpoint of further excellent oxygen permeability and further suppressing cracking of the electrode catalyst layer. The following structure may be, for example, A of the main chain described later.

式（５０）
（式（５０）中、Ｘ₁〜Ｘ₃は、それぞれ独立に、水素原子、フッ素原子、塩素原子を表す。Ａは上記式３５〜式４０を有する側鎖を表す。）；下記式（５１）で表される構造を含む主鎖

式（５１）
（式（５１）中、Ｘ₁〜Ｘ₅のうち、少なくとも２つは、単結合、エーテル基、チオエーテル基、スルホニル基、カルボニル基から選ばれる結合基を表し、それぞれ同一でも異なっても良い。また、上記芳香族環を複数含む場合は、上記結合基を介して芳香族環が結合していてもよい。上記結合基を介して隣り合う構造単位の主鎖と結合する。上記結合基以外のＸ₁〜Ｘ₅はそれぞれ独立に、水素原子、フッ素原子、フッ素化されていてもよい炭素数１〜１０のアルキル基を表す。Ａは、上記側鎖を有する部位を表し、上記芳香族環が複数あるときは、少なくとも一つの芳香族環のＡが上記側鎖（例えば、式４１〜式４６を有する部位）を有していればよい。）等の少なくとも１つの芳香族環と少なくとも１つのエーテル結合とを含む主鎖；下記式（５２）で表される主鎖

式（５２）
（式（５２）中、ｎは構造単位の繰り返し数を表し、Ａは、上記側鎖を有する部位（例えば、式４１〜式４６を有する部位）を表す。）；等が挙げられる。
上記主鎖としては、−（ＣＦ₂−ＣＦＡ）−、−（ＣＨ₂−ＣＨＡ）−等のエチレン系主鎖；ポリエーテルケトン（ＰＥＫ）、ポリエーテルエーテルケトン（ＰＥＥＫ）、ポリエーテルスルホン（ＰＥＳ）、ポリフェニレンエーテル（ＰＰＥ）等の主鎖にエーテル結合を有する主鎖；が好ましく、中でも、電池性能、化学耐久性の観点から、−（ＣＦ₂−ＣＦＡ）−が好ましい。 The main chain of the structural unit A is not particularly limited, but for example, the main chain of the structure represented by the following formula (50).

Equation (50)
(In the formula (50), X _{1 to} X ₃ independently represent a hydrogen atom, a fluorine atom, and a chlorine atom. A represents a side chain having the above formulas 35 to 40.); The following formula (51). ) Main chain containing the structure represented by

Equation (51)
(In the formula (51) _{, at least two of X 1 to} X ₅ represent a binding group selected from a single bond, an ether group, a thioether group, a sulfonyl group, and a carbonyl group, and may be the same or different from each other. When a plurality of the aromatic rings are contained, the aromatic rings may be bonded via the bonding group. The aromatic rings are bonded to the main chains of adjacent structural units via the bonding groups. Other than the bonding groups. X _{1 to} X ₅ independently represent a hydrogen atom, a fluorine atom, and an alkyl group having 1 to 10 carbon atoms which may be fluorinated. A represents a site having the side chain and the aromatic. When there are a plurality of rings, at least one aromatic ring such as A of at least one aromatic ring may have the above side chain (for example, a site having formulas 41 to 46) and at least one aromatic ring. Main chain containing one ether bond; main chain represented by the following formula (52)

Equation (52)
(In formula (52), n represents the number of repetitions of the structural unit, and A represents a portion having the side chain (for example, a portion having formulas 41 to 46); and the like.
Examples of the main chain include _{ethylene-based main chains such as-(CF 2-} CFA) _{-and-(CH 2-} CHA)-; polyetherketone (PEK), polyetheretherketone (PEEK), and polyethersulfone (PES). ), A main chain having an ether bond in the main chain such as polyphenylene ether (PPE); among them,-(CF _2- CFA)-is preferable from the viewpoint of battery performance and chemical durability.

(Other structural units)
The other structural unit may be a structural unit having the same main chain as the structural unit A and not having the side chain. The other structural unit is, for example, a structural unit having the same main chain as the structural unit A and having no side chain, and a side chain having the same main chain as the structural unit A and promoting proton conductivity. It may be a structural unit having.

式（５３）
（式（５３）中、Ｘは、Ｆ、Ｃｌ、又は置換されていてもよい炭素数１〜３のフッ素化炭化水素基を表す。ｋは０〜２の整数、ｎは０〜８の整数を表す。ｎ個のＸは、同一でも異なっていてもよい。Ｙは、Ｆ又はＣｌを表す。ｍは１〜６の整数を表す。ｍ個のＹは、同一でも異なっていてもよい。Ｚは、Ｈ、アルカリ金属、又はアルカリ土類金属表す。）
上記式（５３）において、特に、ｋが０又は２、ｎが０、ｍが２、ＹがＦ、ＺがＨであることが好ましい。

式（５４）
（式（５４）中、Ｘは、Ｆ、Ｃｌ、又は置換されていてもよい炭素数１〜３のフッ素化炭化水素基を表す。ｋは０〜２の整数、ｎは０〜８の整数を表す。ｎ個のＸは、同一でも異なっていてもよい。Ｙは、Ｆ又はＣｌを表す。ｍは１〜６の整数を表す。ｍ個のＹは、同一でも異なっていてもよい。Ｚは、ＮＲ¹Ｒ²を表す。Ｒ¹及びＲ²は、それぞれ独立に、置換されていてもよい炭素数１〜１０のアルキル基、水素原子、−ＳＯ₂−Ｒ³を表す。ここでＲ³は炭素数１〜１０の炭化水素基を表す。Ｒ¹、Ｒ²の一方が置換されても良いアルキル基又は水素であるとき、Ｒ²は−ＳＯ₂−Ｒ³である。）
上記式（５４）において、特に、ｋが０又は２、ｎが０、ｍが２であることが好ましい。

式（５５）
（式（５５）中、Ｒｆ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、単結合を表す。Ｘは、Ｈ、アルカリ金属、又はアルカリ土類金属を表す。）

式（５６）
（式（５６）中、Ｒｆ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、単結合を表す。ＸはＮＲ¹Ｒ²を表す。Ｒ¹及びＲ²は、それぞれ独立に、置換されていてもよい炭素数１〜１０のアルキル基又は水素、−ＳＯ₂−Ｒ³を表す。ここでＲ³は炭素数１〜１０の炭化水素基を表す。Ｒ¹、Ｒ²の一方が置換されても良いアルキル基又は水素であるとき、Ｒ²は−ＳＯ₂−Ｒ³である。） The fluorine-containing polymer electrolyte of the present embodiment may have a side chain that promotes proton conductivity.
The side chain that promotes proton conductivity preferably has a structure represented by the following formulas (53) to (56).

Equation (53)
(In formula (53), X represents F, Cl, or a fluorinated hydrocarbon group having 1 to 3 carbon atoms which may be substituted. K is an integer of 0 to 2, and n is an integer of 0 to 8. The n Xs may be the same or different. Y represents F or Cl. M represents an integer of 1-6. The m Ys may be the same or different. Z represents H, an alkali metal, or an alkaline earth metal.)
In the above formula (53), it is particularly preferable that k is 0 or 2, n is 0, m is 2, Y is F, and Z is H.

Equation (54)
(In formula (54), X represents F, Cl, or a fluorinated hydrocarbon group having 1 to 3 carbon atoms which may be substituted. K is an integer of 0 to 2, and n is an integer of 0 to 8. The n Xs may be the same or different. Y represents F or Cl. M represents an integer of 1-6. The m Ys may be the same or different. Z represents ^{NR 1} R ^{2. R 1} and R ² each independently represent an alkyl group having 1 to 10 carbon atoms, a hydrogen atom, and −SO ₂ −R ³ . R ³ represents a hydrocarbon group having 1 to 10 carbon atoms. When ^one of R ^{1 and R 2} is an alkyl group or hydrogen which may be substituted, R ² is −SO _{2 −} R ³ ).
In the above formula (54), it is particularly preferable that k is 0 or 2, n is 0, and m is 2.

Equation (55)
(In the formula (55), Rf independently represents a fluorinated hydrocarbon group having 1 to 10 carbon atoms containing an ether-bonding oxygen atom and a single bond. X is H, an alkali metal, or an alkaline earth metal. Represents.)

Equation (56)
(In the formula (56), Rf independently represents a fluorinated hydrocarbon group having 1 to 10 carbon atoms containing an ether-bonding oxygen atom, and a single bond. X represents NR ¹ R ^2. R ¹ and R 2. ² represents an alkyl group or hydrogen having 1 to 10 carbon atoms which may be substituted independently, and −SO ₂ −R ³ where R ³ represents a hydrocarbon group having 1 to 10 carbon atoms. When ^{one of} R 1 and R ² is an alkyl group or hydrogen which may be substituted, R ² is −SO _{2 −} R ³ ).

式（５７）
（式（５７）中、Ｒｆは炭素数１〜１０のフッ素化炭化水素基を表す。上記フッ素化炭化水素基は構造中にエーテル性酸素原子を含んでも良い。）
上記側鎖（Ｄ）としては、−Ｏ−ＣＦ₃、−Ｏ−Ｃ₂Ｆ₅、−Ｏ−Ｃ₃Ｆ₇、−Ｏ−Ｃ₂Ｆ₄−Ｏ−Ｃ₂Ｆ₅、−Ｏ−（ＣＦ₂ＣＦ（ＣＦ₃））−Ｏ−Ｃ₃Ｆ₇、等が挙げられる。 The other structural unit may include a structural unit having a side chain (D) having a structure represented by the following formula (57), and the side chain is added to A of _{− (CF 2-CFA) −.} It may be a structural unit in which (D) is directly bonded. By introducing the structural unit having the side chain (D), it becomes possible to adjust the solubility in a solvent when preparing a fluorine-containing polymer electrolyte solution.

Equation (57)
(In the formula (57), Rf represents a fluorinated hydrocarbon group having 1 to 10 carbon atoms. The fluorinated hydrocarbon group may contain an ethereal oxygen atom in the structure.)
The side chains (D) include -O-CF ₃ , -O-C ₂ F ₅ , -O-C ₃ F ₇ , -O-C ₂ F ₄ -O-C ₂ F ₅ , -O- ( CF ₂ CF (CF ₃ ))-OC ₃ F ₇ , and the like can be mentioned.

Examples of the main chain in the other structural unit include the same as the main chain in the structural unit A described above.

(Content ratio of structural units)
The ratio of the structural unit A in the fluorine-containing polymer electrolyte of the present embodiment can be determined by the following introduction rate.
The introduction rate is preferably 1.0 mol% or more and 80.0 mol% or less, more preferably 10.0 mol% or more and 70.0 mol% or less, and further preferably 10.0 mol% or more and 60.0 mol% or less. When the introduction rate is 1.0 mol% or more, cracks in the electrode catalyst layer are further suppressed, the oxygen permeability is high, and the durability is further excellent. Further, when it is 80.0 mol% or less, the proton conductivity is also excellent, and the battery performance is further excellent.
The introduction rate can be measured by the method described in Examples described later.

(Characteristic)
The fluorine-containing polymer electrolyte of the present embodiment preferably has an equivalent weight EW (the number of dry mass grams of the fluorine-containing polymer electrolyte per equivalent of a proton exchange group) of 100 to 2000 g / eq. That is, it is preferable to control the copolymerization ratio and the proton conductive group introduction rate so as to be within the above EW range. The upper limit of the EW is preferably 1000 g / eq, more preferably 900 g / eq. The lower limit of the EW is preferably 300 g / eq, more preferably 500 g / eq. When the EW is within the above range, the processability is further excellent, the conductivity of the electrode catalyst layer is not too low, and the solubility in hot water is also small.
The equivalent weight EW can be measured by the method described in Examples described later.

The number average molecular weight of the fluorine-containing polymer electrolyte of the present embodiment is preferably 10,000 to 2 million, more preferably 30,000 to 1,000,000, because the processability, electrical conductivity, and mechanical strength are further excellent. Is.
The number average molecular weight is a value measured by a GPC (gel permeation chromatography) method. For example, the number average molecular weight can be calculated with reference to standard polystyrene by the method shown below.
Using HLC-8020 manufactured by TOSOH, the column should be three polystyrene gel MIX columns (Tosoh GMH series, 30 cm size), 40 ° C., NMP (containing 5 mmol / L LiBr) solvent, and a flow rate of 0.7 mL / min. Can be done. The sample concentration can be 0.1% by mass and the driving amount can be 500 μL. Those having a number average molecular weight of about 100,000 to 800,000 in terms of polystyrene are further preferable, those of about 130,000 to 700,000 are even more preferable, and those of about 160,000 to 600,000 are particularly preferable.

The melt flow rate (MFR) of the fluorine-containing polymer electrolyte of the present embodiment is preferably 0.1 to 1000 g / 10 minutes because it is more excellent in processability, electrical conductivity and mechanical strength. It is more preferably 5 g / 10 minutes or more, further preferably 1.0 g / 10 minutes or more, further preferably 200 g / 10 minutes or less, and further preferably 100 g / 10 minutes or less.
The MFR can be measured 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.

(Production method)
The fluorine-containing polymer electrolyte may be obtained by polymerizing a monomer capable of forming a predetermined structural unit, or a predetermined side chain may be introduced into the polymer after the polymerization.
The fluorine-containing polymer electrolyte can be synthesized by conventionally known methods such as polycondensation, radical polymerization, and anionic polymerization. Among them, polycondensation or radical polymerization is preferably used.
The fluorine-containing polymer electrolyte can be obtained in the form of an emulsion in which the fluorine-containing polymer electrolyte particles are dispersed or dissolved in water.

The radical polymerization may be carried out in the presence of a surfactant. As the surfactant, a known fluorine-containing anionic surfactant is preferable.

The radical polymerization is preferably carried out by adding a polymerization initiator. The polymerization initiator is not particularly limited as long as it can generate radicals at the polymerization temperature, and known oil-soluble and / or water-soluble polymerization initiators can be used. You may also use a redox initiator. The concentration of the polymerization initiator is appropriately determined depending on the molecular weight and reaction rate of the target polymer.
Examples of the polymerization initiator include persulfates such as ammonium persulfate and potassium persulfate, and organic peroxides such as disuccinic acid peroxide, diglutaric acid peroxide, and tert-butyl hydroperoxide. The redox initiator is a combination of a persulfate or an organic peroxide, a sulfite such as sodium sulfite, a bisulfite such as sodium bisulfite, and a reducing agent such as bromate, diimine, and oxalic acid. Can be mentioned.

Radical polymerization can be carried out under a pressure of 0.05 to 5.0 MPa. The preferred pressure range is 0.1 to 1.5 MPa. In addition, radical polymerization can be carried out at a temperature of 5 to 100 ° C. The preferred temperature range is 10 to 90 ° C. In radical polymerization, known stabilizers, chain transfer agents and the like may be added depending on the purpose.

The fluorine-containing polymer electrolyte may be obtained by fluorination. As a method of fluorination, for example, as described in Japanese Patent Application Laid-Open No. 2004-143622, a mixed gas obtained by diluting fluorine gas or fluorine gas with an inert gas (for example, nitrogen, argon, helium, carbon dioxide gas, etc.) Can be applied by contacting the object to be treated.

(Fluorine-containing polymer electrolyte solution)
The fluoropolymer electrolyte solution of the present embodiment preferably contains the fluoropolymer electrolyte and a solvent (for example, water, an organic solvent, etc.), and the fluoropolymer electrolyte and water and / or an organic solvent. It is more preferable to include. The fluorine-containing 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 fluorine-containing polymer electrolyte solution is preferably a fluorine-containing polymer electrolyte solution for forming an electrode catalyst layer of a fuel cell.

The mass ratio of the fluorine-containing polymer electrolyte in the fluorine-containing polymer electrolyte solution is preferably 2 to 50% by mass, more preferably 5% by mass or more, and preferably 10% by mass or more. It is more preferably 40% by mass or less, further preferably 30% by mass or less, and particularly preferably 25% by mass or less.

Examples of the organic solvent include protic organic solvents such as methanol, ethanol, n-propanol, isopropyl alcohol, butanol and glycerin, and aprotics such as N, N-dimethylformamide, N, N-dimethylacetamide and N-methylpyrrolidone. Solvents, etc. may be mentioned. These can be used alone or in combination of two or more.

The fluorine-containing polymer electrolyte solution may contain an organic additive. Further, the fluorine-containing polymer electrolyte solution may contain an inorganic additive.

Examples of the organic additive include compounds in which atoms are easily extracted by radicals, for example, compounds having a hydrogen bonded to a tertiary carbon, a carbon-halogen bond, or the like in the structure. Specifically, aromatic compounds partially substituted with the above functional groups such as polyaniline, polybenzimidazole, polybenzoxazole, polybenzothiazole, polybenzoxadiazole, phenylated polyquinoxalin, phenylated polyquinolin, etc. An unsaturated heterocyclic compound of the above can be mentioned.
Also mentioned are thioether compounds. For example, dialkyl thioethers such as dimethyl thioether, diethyl thio ether, dipropyl thio ether, methyl ethyl thio ether, methyl butyl thio ether; cyclic thio ethers such as tetrahydrothiophene, tetrahydroapirane; methyl phenyl sulfide, ethyl phenyl sulfide, diphenyl sulfide, dibenzyl. Aromatic thioethers such as sulfide; and the like.

The mass ratio of the organic additive in the fluorine-containing polymer electrolyte solution is preferably 0.1% by mass or more, more preferably 1% by mass or more, still more preferably 3% by mass or more. By containing 0.1% by mass or more of the above organic additive, it is possible to improve the chemical durability in fuel cell operation.

Examples of the inorganic additive include metal oxides, metal carbonates, metal nitrates and the like. Each of these inorganic additives may be used alone, or a mixture of two or more kinds may be used.
Examples of the metal oxide include zirconia (ZrO ₂ ), titania (TiO ₂ ), silica (SiO ₂ ), alumina (Al ₂ O ₃ ), iron oxide (Fe ₂ O ₃ , FeO, Fe ₃ O ₄ ), and the like. Copper oxide (CuO, Cu ₂ O), zinc oxide (ZnO), yttrium oxide (Y ₂ O ₃ ), niobide 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 ), Celium Oxide (CeO ₂ , Ce ₂ O ₃ ), Antimon Oxide (Sb ₂ O ₃ , Sb ₂ O ₅ ), Germanium Oxide (GeO ₂ , GeO), Lantern Oxide (La ₂ O ₃ ), Luthenium Oxide (RuO ₂ ) , Manganese oxide (MnO), and the like. These metal oxides may be used alone or as a mixture, and for example, tin-added indium oxide (ITO), antimony-added tin oxide (ATO), zinc aluminum oxide (ZnO / Al ₂ O ₃ ), etc. The composite oxides listed in the above can be mentioned.
Examples of the metal carbonate 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 ), manganese carbonate (MnCO ₃ ), and the like.
Examples of the metal nitrate 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 (NO ₃ ) ₃ ), nickel nitrate (Ni (NO ₃ ) ₂ ), cobalt nitrate (Co (NO ₃ ) ₂ ), manganese nitrate (Mn (NO ₃ ) ₂ ), and the like.

The mass ratio of the inorganic additive in the fluorine-containing polymer electrolyte solution is preferably 0.1% by mass or more, more preferably 1% by mass or more, still more preferably 3% by mass or more. By containing 0.1% by mass or more of the above-mentioned inorganic additive, it is possible to improve the chemical durability in fuel cell operation.

When the fluorine-containing polymer electrolyte solution contains an organic solvent, it preferably further contains water, and the mass ratio of the organic solvent to water is preferably 10/90 to 90/10, and is 30/70 or more. It is more preferable that there is, and it is more preferable that it is 70/30 or less.

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

The fluorine-containing polymer electrolyte solution is more preferably filtered from the viewpoint of removing coarse particle components. The filtration method is not particularly limited, and a conventional general method can be applied. For example, a method of pressurizing filtration using a filter obtained by processing a filter medium having a rated filtration accuracy, which is usually used, can be typically mentioned. As for the filter, it is preferable to use a filter medium having a 90% collection particle size of 10 to 100 times the average particle size of the particles. This filter medium may be a filter paper or a filter medium such as a metal sintered filter. Especially in the case of filter paper, it is preferable that the 90% collected particle size is 10 to 50 times the average particle size of the particles. In the case of a metal sintered filter, it is preferable that the 90% collected particle size is 50 to 100 times the average particle size of the particles. Setting the 90% collected particle size to 10 times or more the average particle size prevents the pressure required for liquid transfer from becoming too high and prevents the filter from clogging in a short period of time. Can be suppressed. On the other hand, setting it to 100 times or less the average particle size is preferable from the viewpoint of satisfactorily removing agglomerates of particles and undissolved resin which may cause foreign substances in the film.

(Fluorine-containing polymer electrolyte-containing composition (electrode catalyst ink))
The fluorine-containing polymer electrolyte can be suitably used as a raw material for forming the electrode catalyst ink. The electrode catalyst ink preferably contains the fluorine-containing polymer electrolyte, a solvent (for example, water and / or an organic solvent), 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 according to the purpose of use of the fuel cell in which the electrode catalyst layer is used. The catalyst is preferably a catalyst metal.
The catalyst is preferably a metal that promotes the oxidation reaction of hydrogen and the reduction reaction of oxygen, and is preferably platinum, gold, silver, palladium, iridium, rhodium, ruthenium, iron, cobalt, nickel, chromium, tungsten, manganese, etc. More preferably, it is at least one metal selected from the group consisting of vanadium and alloys thereof. Of these, platinum is preferable.

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 fluorine-containing polymer electrolyte in the electrode catalyst ink is preferably 5 to 30% by mass, more preferably 8% by mass or more, and 10% by mass with respect to the electrode catalyst ink. The above is more preferable, 20% by mass or less is more preferable, and 15% by mass or less is further preferable.
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 100% by mass or more with respect to the fluorine-containing polymer electrolyte. It is more preferably 150% by mass or less, and further preferably 130% by mass or less.

The electrode catalyst ink preferably further contains a conductive agent. It is also one of the preferable forms that the catalyst and the conductive agent are composite particles (for example, Pt-supported carbon or the like) composed of the conductive agent supporting the particles of the catalyst. In this case, the fluorine-containing polymer electrolyte also functions as a binder.

The conductive agent is not limited as long as it is conductive particles (conductive particles), but for example, from carbon black such as furnace black, channel black, acetylene black, activated carbon, graphite and various metals (excluding catalyst metal). It is preferable that it is at least one kind of conductive particles selected from the group. 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.

As the composite particles, the content of the catalyst particles with respect 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, Pt catalyst-supported carbons such as TEC10E40E, TEC10E50E, and TEC10E50HT manufactured by Tanaka Kikinzoku Kogyo Co., Ltd. are preferable examples.

The content of the composite particles is preferably 1.0 to 3.0% by mass, more preferably 1.4 to 2.9% by mass, and further preferably 1. It is 7 to 2.9% by mass, particularly preferably 1.7 to 2.3% by mass.

The electrode catalyst ink may further contain a water repellent.
The electrode catalyst ink further contains polytetrafluoroethylene (hereinafter referred to as PTFE) and a copolymer of tetrafluoroethylene and perfluoro (2,2-dimethyl-1,3-dioxol) in order to improve water repellency. You may. In this case, the shape of the water repellent is not particularly limited, but it may be a fixed form, preferably in the form of particles or fibers, and even if these are used alone, they are mixed and used. May be good.

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

The electrode catalyst ink may contain an inorganic additive in order to improve hydrophilicity and chemical durability.
Examples of the inorganic additive include metal oxides, metal carbonates, metal nitrates and the like.
Each of these inorganic additives may be used alone, or a mixture of two or more kinds may be used. Specifically, examples of the metal oxide include zirconia (ZrO ₂ ), titania (TiO ₂ ), silica (SiO ₂ ), alumina (Al ₂ O ₃ ), iron oxide (Fe ₂ O ₃ , FeO, Fe _3). O ₄ ), copper oxide (CuO, Cu ₂ O), zinc oxide (ZnO), yttrium oxide (Y ₂ O ₃ ), niobide 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 ), manganese oxide (MnO) and the like can be mentioned. These metal oxides may be used alone or as a mixture, and for example, tin-added indium oxide (ITO), antimony-added tin oxide (ATO), zinc aluminum oxide (ZnO / Al ₂ O ₃ ), etc. The composite oxides listed in the above can be mentioned.
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 ), manganese carbonate (MnCO ₃ ) and the like.
Examples of metallic nitrates include zirconium nitrate (Zr (NO ₃ ) ₄ ), iron nitrate (Fe (NO ₃ ) ₃ ), copper nitrate (Cu (NO ₃ ) ₂ ), titanium nitrate (Ti (NO ₃ ) ₄ ), and the like. Examples thereof include cerium nitrate (Ce (NO ₃ ) ₃ ), nickel nitrate (Ni (NO ₃ ) ₂ ), cobalt nitrate (Co (NO ₃ ) ₂ ), and manganese nitrate (Mn (NO ₃ ) _{2).
Among them, silica (SiO 2} ) is preferable from the viewpoint of improving hydrophilicity, and _{cerium oxide (CeO 2} , Ce ₂ O ₃ ), manganese oxide (MnO), cerium carbonate (CeCO ₃ ), manganese carbonate from the viewpoint of improving chemical durability. (MnCO ₃ ), cerium nitrate (Ce (NO ₃ ) ₃ ), manganese nitrate (Mn (NO ₃ ) ₂ ), titanium nitrate (Ti (NO ₃ ) ₄ ) are preferable.

As the form of the inorganic additive, particles or fibrous ones may be used, but it is particularly desirable that the inorganic additive has an atypical form. The term "atypical" as used herein means that no particle-like or fibrous metal oxide is observed even when observed with an optical microscope or an electron microscope. In particular, even when the electrode catalyst layer is magnified up to several hundred thousand times and observed using a scanning electron microscope (SEM), no particle-like or fibrous metal oxide is observed. Further, even when the electrode catalyst layer is magnified several hundred thousand times to several million times by a transmission electron microscope (TEM) and observed, the particle-like or fibrous metal oxide can be clearly observed. Can not. As described above, it means that it is not possible to confirm the particle shape or fibrous shape of the metal oxide within the scope of the current microscope technology.

The content of the inorganic additive is preferably 0.01 to 100% by mass, more preferably 0.01 to 45% by mass, still more preferably 0.01, based on the fluorine-containing polymer electrolyte. It is ~ 25% by mass, particularly preferably 0.5 to 6.0% by mass.

(Electrode catalyst layer)
The electrode catalyst layer of the present embodiment is preferably an electrode catalyst layer containing the above-mentioned fluorine-containing polymer electrolyte. The electrode catalyst layer is preferably made of the 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 a fuel cell.

The electrode catalyst layer is preferably composed of the fluorine-containing polymer electrolyte and the catalyst. The electrode catalyst layer, the supported amount of the fluorine-containing polymer electrolyte to the electrode area is preferably 0.001 to 10 mg / cm ^2, more preferably 0.01 to 5 mg / cm ^2, more preferably 0.1 It is 1 mg / cm ² .

The electrode catalyst layer of the present embodiment is preferably made of a fluorine-containing polymer electrolyte, a catalyst, and a conductive agent. It is also preferable that the electrode catalyst layer is composed of a fluorine-containing polymer electrolyte, composite particles composed of catalyst particles and a conductive agent supporting the catalyst particles (for example, Pt-supported carbon). is there. In this case, the fluorine-containing polymer electrolyte also functions as a binder.

Examples of the above-mentioned conductive agent include those mentioned above, and those similar to those described above are preferable.
As the composite particles, the catalyst particles are preferably 1 to 99% by mass, more preferably 10 to 90% by mass, and most preferably 30 to 70% by mass with respect to the conductive particles. Specifically, Pt catalyst-supported carbon such as TEC10E40E manufactured by Tanaka Kikinzoku Kogyo Co., Ltd. is a preferable example.

The content of the composite particles is preferably 20 to 95% by mass, more preferably 40 to 90% by mass, still more preferably 50 to 85% by mass, and particularly preferably 60, based on the total mass of the electrode catalyst layer. ~ 80% by mass. When the electrode catalyst layer is used as the electrode catalyst layer of the fuel cell, the amount of the catalyst metal supported with respect to the electrode area is preferably 0.001 to 10 mg / cm ² in the state where the electrode catalyst layer is formed, more preferably 0. .01~5mg / cm ^2, more preferably 0.1 to 1 mg / cm ^2, even more preferably 0.2-0.5 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.
Examples of the water repellent include those described above, and those similar to those described above are preferable.
When the electrode catalyst layer contains a water repellent, the content of PTFE and the copolymer of tetrafluoroethylene and perfluoro (2,2-dimethyl-1,3-dioxol) is the total mass of the electrode catalyst layer. On the other hand, it 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.

The electrode catalyst layer may contain an inorganic additive in order to improve hydrophilicity and chemical durability.
Examples of the above-mentioned inorganic additive include those mentioned above, and those similar to the above are preferable.
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 with respect to the total mass of the electrode catalyst layer. %.

The porosity of the electrode catalyst layer is not particularly limited, but is preferably 10 to 90% by volume, more preferably 20 to 80% by volume, and most preferably 30 to 60% by volume.

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

The step of preparing the electrode catalyst ink by dispersing the catalyst in the obtained fluorine-containing polymer electrolyte solution comprises the catalyst particles and the conductive agent carrying the catalyst particles in the obtained emulsion or the fluorine-containing polymer electrolyte solution. It is preferable to prepare an electrode catalyst ink in which composite particles are dispersed.

For the application of the electrode catalyst ink, various generally known methods such as a screen printing method and a spray method can be used.

(Membrane electrode assembly)
The membrane electrode assembly (membrane / ejectorode assembly) (hereinafter, also referred to as “MEA”) of the present embodiment preferably includes the electrode catalyst layer. Since the membrane electrode assembly of the present embodiment includes the electrode catalyst layer, it is excellent in battery characteristics, mechanical strength, and stability. The membrane electrode assembly can be suitably used for a fuel cell.

A unit in which two types of electrode catalyst layers, an anode and a cathode, are bonded to both sides of an electrolyte membrane is called a membrane electrode assembly (hereinafter, also referred to as "MEA"). A pair of gas diffusion layers bonded to the outer side of the electrode catalyst layer so as to face each other may also be referred to as MEA. The electrode catalyst layer needs to have proton conductivity.

The electrode catalyst layer as an anode includes a catalyst that oxidizes a fuel (for example, hydrogen) to easily generate a proton, and the electrode catalyst layer as a cathode contains protons, electrons, and an oxidant (for example, oxygen or air). Includes catalysts that react to produce water. As the catalyst, the above-mentioned catalyst metal can be preferably used for both the anode and the cathode.

As the gas diffusion layer, commercially available carbon cloth, carbon paper, carbon felt or the like can be used. It is preferable that these gas diffusion layers are water-repellent treated with polytetrafluoroethylene or the like.
Specific examples include carbon fiber trading cards (manufactured by Toray Industries, Inc.), pyrofil (manufactured by Mitsubishi Chemical Corporation), SIGRACET GDL (manufactured by MFC Technology), and the like.

The MEA can be produced, for example, by sandwiching an electrolyte membrane between the electrode catalyst layers and joining them by a hot press. More specifically, a commercially available platinum-supported carbon (for example, TEC10E40E manufactured by Tanaka Kikinzoku Co., Ltd.) is dispersed as a catalyst in a mixture of the above-mentioned fluorine-containing polymer electrolyte dispersed or dissolved in a mixed solution of alcohol and water and pasted. Make it into a shape. A certain amount of this is applied to one side of each of the two PTFE sheets and dried to form an electrode catalyst layer. Next, the coated surfaces of the PTFE sheets are made to face each other, an electrolyte membrane is sandwiched between them, transfer bonding is performed by a hot press at 100 to 200 ° C., and then the PTFE sheet is removed to obtain MEA. A method for producing MEA is well known to those skilled in the art. The method for producing MEA is described in, for example, JOURNAL OF APPLIED ELECTROCHEMISTRY, 22 (1992) p. It is described in detail in 1-7.

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 a general fuel cell such as a bipolar plate and a backing plate to form a fuel cell.

(Fuel cell)
The fuel cell of the present embodiment preferably includes the membrane electrode assembly. The fuel cell of the present embodiment is preferably a polymer electrolyte fuel cell. The fuel cell of the present embodiment is not particularly limited as long as it has the membrane electrode assembly, and may usually include components such as gas constituting the fuel cell. Since the fuel cell of the present embodiment includes the membrane electrode assembly having the electrode catalyst layer, it is excellent in battery characteristics, mechanical strength, and stability.

The bipolar plate means a composite material of graphite and resin having grooves formed on its surface for allowing gas such as fuel or an oxidizing agent to flow, or a metal plate or the like. The bipolar plate has a function of transmitting electrons to an external load circuit and also a function of a flow path for supplying fuel and an oxidizing agent in the vicinity of the electrode catalyst. A fuel cell is manufactured by inserting MEA between such bipolar plates and stacking a plurality of MEAs.

Next, the present invention will be described with reference to examples, but the present invention is not limited to such examples.

(Fluorination)
Under room temperature conditions, the sample was fluorinated by exposing it to a mixed gas consisting of 5 vol% of fluorine gas and 95 vol% of nitrogen gas for 30 minutes.

(Ion exchange capacity)
A fluorine-containing polymer electrolyte membrane in which the counter ion of the ion exchange group is in a proton state, approximately ² to 20 cm 2, was immersed in 30 ml of a saturated NaCl aqueous solution at 25 ° C. and left for 30 minutes with stirring. Then, the protons in the saturated NaCl aqueous solution were neutralized and titrated as a 0.01N sodium hydroxide aqueous solution using phenolphthalein as an indicator. The fluorine-containing polymer electrolyte membrane obtained after neutralization in which the counter ion of the ion exchange group was in the state of sodium ion was rinsed with pure water, further vacuum-dried, and weighed. The amount of substance of sodium hydroxide required for neutralization is M (mmol), the weight of the fluoropolymer electrolyte membrane containing sodium ions as the counterion of the ion exchange group is W (mg), and the equivalent weight EW (g) is calculated by the following formula. / Eq) was calculated.
EW = (W / M) -22
Further, the ion exchange capacity (milli equivalent / g) was calculated by taking the reciprocal of the obtained EW value and multiplying it by 1000.

(Introduction rate)
H-NMR and F-NMR analysis of the polymer electrolyte into which the side chain structure was introduced was performed, and the introduction rate of the side chain structure was calculated by combining with the amount of proton conductive groups introduced in the EW measurement. Further, especially when the side chain having a cyclic structure does not have a proton conductive group, the introduction rate was measured as follows.
The EW of the polymer electrolyte into which the side chain structure was introduced was measured by the above-mentioned ion exchange capacity measurement method. The value at that time was set to EW1. Then, charged electrolyte and 6N aqueous hydrochloric acid solution was introduced a side chain structure into the autoclave, and after sufficiently replacing the inside with N ₂ gas, 160 ° C., and out the hydrolysis under the conditions of 8 hours. The obtained polymer electrolyte was washed with distilled water and then dried at 120 ° C. for 1 hour. From H-NMR and F-NMR analysis of the dried resin, it was confirmed that the side chains were completely hydrolyzed. The EW of the polymer electrolyte after hydrolysis was measured. The value at that time was set to EW2. From the above, the amount of side chain introduced (C2) was calculated to be 1000 / (EW1-EW2). Here, when the amount of proton conductive groups before hydrolysis is C1, the side chain introduction rate (S) is represented by C2 / (C1 + C2) × 100 (mol%).
Further, by confirming the structure by 1 H-NMR and F-NMR and using it in combination with EW, the introduction rate of the side chain structure can be measured regardless of the structure at the end of the side chain.

(Moisture content)
The water content of the polymer was measured using a humidifiable TG-DTA (product name: TG-8120, manufactured by Rigaku Co., Ltd.).
First, it is dried at 120 ° C. for 1 hour, then cooled to 80 ° C., kept at a humidity of 80% for 1 hour, and the mass ratio of water contained in the polymer is determined from the difference between the mass under the humidifying condition and the dry mass. That is, the water content (mass%) was calculated.

(Oxygen solubility)
The oxygen solubility of the film of the fluorine-containing polymer electrolyte resin was measured by using the chronoamperometry method. A glass-encapsulated 100 μmφ platinum microelectrode was pressed against a sample having a thickness of about 200 μm to adjust the temperature and humidity. After maintaining the potential at 1100 mV (vs. SHE) in a nitrogen or oxygen atmosphere, the current value was measured in steps of 400 mV. The difference between the current values observed under the atmosphere of nitrogen and oxygen was plotted against the -1 / 2th power of the application time, and the oxygen solubility was calculated using the following formula in 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 (96500 C / 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 the time (s).
In this study, the oxygen solubility at an evaluation temperature of 80 ° C. and a humidity of 80% was shown.

(Oxygen permeability coefficient)
The gas permeability coefficient of oxygen in the membrane sample was measured using a flow-type gas permeability measuring device GTR-30XFAFC manufactured by GTR Tech Co., Ltd. The supply gas flow rate was TEST gas (oxygen) 30 cc / min and carrier gas (He) 100 kPa. As the humidifying and humidifying conditions for the gas, 80 ° C. and 90% RH were adopted.
The oxygen gas that has permeated the membrane sample from the TEST gas side to the FLOW side is introduced into a gas chromatograph G2700TF manufactured by Yanaco Analytical Industry Co., Ltd., and the amount of gas permeation is quantified.
The amount of permeation is X (cc), the correction coefficient is k (= 1.0), the film thickness of the film sample is T (cm), the permeation area is A (cm ² ), the passage time of the measuring tube is D (sec), and oxygen. The gas permeability coefficient P (cc · cm / (cm ² · sec · cmHg)) when the partial pressure is p (cmHg) is calculated from the following formula.
P = (X × k × T / (A × D × p))

(Presence / absence of cracks (SEM observation))
The surface of the catalyst layer produced by the die coater was observed using a scanning electron microscope (product name: VE8800, manufactured by KEYENCE CORPORATION) under the conditions of a magnification of 50 times and an acceleration voltage of 1 kV. As a result of observation, the case where there was no crack on the surface of the catalyst layer was described as A (good), and the case where crack was observed was described as B (defective).

(Catalyst paste preparation, electrode preparation, fuel cell evaluation)
In order to evaluate the performance of MEA under high temperature and low humidification conditions, a power generation test was carried out according to the following procedure.
(1) Preparation of electrode catalyst ink A fluorine-containing polymer electrolyte solution having a solid content concentration of 15% by mass and an electrode catalyst (TEC10E40E, manufactured by Tanaka Kikinzoku Kogyo Co., Ltd., platinum carrying amount 36.7 wt%) are used as platinum / perfluorosulfonic acid. The polymer was blended to 1 / 1.15 (mass), and then ethanol was added so that the solid content (sum of the electrode catalyst and the perfluorosulfonic acid polymer) was 11 wt%, and a homogenizer (manufactured by AS ONE) was added. The 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.), on a Teflon (registered trademark) substrate (product name: Naflon tape, manufactured by Nichias Corporation) with a thickness of 100 μm. The electrode catalyst ink was applied so that the amount of platinum was 0.2 mg / cm ^2, and dried and solidified at 160 ° C. for 5 minutes to obtain a catalyst layer.
(3) Preparation of MEA Using a press machine (product name: SFA-37, manufactured by Shinto Metal Industry Co., Ltd.), as a fluoropolymer electrolyte on both sides of the electrolyte membrane (product name: NafionHP, manufactured by Chemers) on the anode side. MEA was obtained by hot-pressing the electrode catalyst layer using NafionDE2020CS and the electrode catalyst layer using the fluoropolymer electrolyte of the present embodiment on the cathode side under the conditions of a temperature of 160 ° C. and a pressure of 13 MPa.
(4) Preparation of fuel cell single cell A fuel cell single cell was obtained by superimposing a gas diffusion layer (product name: GDL35BC, manufactured by MFC Technology) on both poles of the above MEA, and then superimposing a gasket, a bipolar plate, and a backing plate. ..
(5) Power generation test The above fuel cell single cell was set in an evaluation device (fuel cell evaluation system 890CL manufactured by Toyo Technica Co., Ltd.), and a power generation test was carried out.
The test conditions for power generation were set at a cell temperature of 65 ° C. and a humidifying bottle of the anode and cathode of 60 ° C., and hydrogen gas was supplied to the anode side and air gas was supplied to the cathode side at 900 ml / min, respectively. In addition, both the anode side and the cathode side were unpressurized (atmospheric pressure).
Under the above evaluation conditions, the voltages at current densities of 0.2 A / cm ² and 1.0 A / cm ² are shown.
(6) Chemical durability test Set the above fuel cell single cell in the evaluation device (fuel cell evaluation system 890CL manufactured by Toyo Technica), and set the cell temperature at 90 ° C, the humidification bottle at 61 ° C (relative humidity 30% RH), and on the anode side. The OCV test was carried out by circulating hydrogen gas and air gas on the cathode side under the conditions of 300 cc / min, respectively.
In order to determine the end point of the OCV test, a micro gas chromatograph (product name: CP-4900, manufactured by GL Science Co., Ltd.) was connected to the cathode side, and the concentration of _{H 2 gas transmitted from the anode side was measured.} The end point was when the concentration of the _{H 2 gas exceeded 1000 ppm.} When the end point is 200 hours or more, it is described as A (good), and when it is less than 200 hours, it is described as B (bad).

(Example 1)
Sodium hydride (0.27 g) was added to a 100 mL three-necked flask, the inside of the system was replaced with nitrogen, and 4-piperidone ethyleneketal (1.36 g) was dissolved while the flask was placed in an ice bath. A solution of 2-dimethoxyethane (40 mL) was added dropwise. _{Next, a copolymer (5.0 g) of tetrafluoroethylene and CF 2} = CFOCF ₂ CF ₂ SO ₂ F obtained by a radical polymerization method was put into a flask and reacted at 80 ° C. for 2 hours. .. After the reaction, 4M hydrochloric acid (100 mL) was added, and then the reaction product was taken out from the flask and washed thoroughly with hot water at 80 ° C. The reaction product is brought into contact with an aqueous solution of potassium hydroxide (15% by mass) and methanol (50% by mass) at 80 ° C. for 20 hours, immersed in water at 60 ° C. for 5 hours, and then 2N hydrochloric acid at 60 ° C. After repeating the treatment of immersing in an aqueous solution for 1 hour 5 times, the mixture was washed with ion-exchanged water and dried to obtain a fluorine-containing polymer electrolyte (A1) (4.2 g).
The obtained fluorine-containing polymer electrolyte (A1) and an aqueous ethanol solution (water: ethanol = 30: 70 (mass ratio)) are placed in a 5 L autoclave, sealed, and heated to 160 ° C. for 3 hours with stirring. Retained. Then, the autoclave was naturally cooled to prepare a uniform polymer solution having a solid content concentration of 10% by mass.
The obtained polymer solution having a solid content concentration of 10% by mass was concentrated under reduced pressure at 80 ° C. to obtain a polymer solution (AS1) having a solid content concentration of 15% by mass.
The AS1 was cast to produce a film (AM1) having a thickness of 200 μm. The EW of AM1 was 832, and the introduction rate of 4-piperidone ethylene ketal introduced into the side chain was 10.3 mol%.
Table 1 shows the EW, water content, oxygen solubility and oxygen permeability coefficient of AM1. Table 2 shows the presence or absence of cracks in the catalyst layer using AS1, the battery performance, and the results of the chemical durability test.
AM1 exhibits high oxygen solubility and oxygen permeability coefficient. Further, it can be seen that the catalyst layer using AS1 has no cracks, and the battery performance and chemical durability are higher than those of the comparative material.

(Example 2)
The A1 obtained in Example 1 was fluorinated by the above method to obtain a fluorinated product A2.
A2 was solubilized in the same manner as in Example 1 to obtain a polymer solution (AS2).
The AS2 was cast to produce a film (AM2) having a thickness of 200 μm. The EW of AM2 was 933, and the introduction rate of perfluoro4-piperidone ethylene ketal introduced into the side chain was 10.1 mol%.
Table 1 shows the EW, water content, oxygen solubility and oxygen permeability coefficient of AM2. Table 2 shows the presence or absence of cracks in the catalyst layer using AS2, the battery performance, and the results of the chemical durability test.
AM2 exhibits high oxygen solubility and oxygen permeability coefficient. Further, it can be seen that the catalyst layer using AS2 has no cracks, and the battery performance and chemical durability are higher than those of the comparative material.

(Example 3)
Synthesis was carried out in the same manner as in Example 1 except that 2,6-dimethylmorpholin (0.95 g) was used instead of 4-piperidone ethylene ketal to obtain a fluorine-containing polymer electrolyte (A3).
The obtained A3 was fluorinated by the above method.
The fluorinated A2 was solubilized in the same manner as in Example 1 to obtain a polymer solution (AS3).
The AS3 was cast to produce a film (AM3) having a thickness of 200 μm. The EW of AM3 was 923, and the introduction rate of perfluoro2,6-dimethylmorpholin introduced into the side chain was 10.1 mol%.
Table 1 shows the EW, water content, oxygen solubility and oxygen permeability coefficient of AM3. Table 2 shows the presence or absence of cracks in the catalyst layer using AS3, the battery performance, and the results of the chemical durability test.
AM3 exhibits high oxygen solubility and oxygen permeability coefficient. Further, it can be seen that the catalyst layer using AS3 has no cracks, and the battery performance and chemical durability are higher than those of the comparative material.

(Example 4)
Synthesis was carried out in the same manner as in Example 1 except that 1-aza-15-crown-5-ether (2.28 g) was used instead of 4-piperidone ethylene ketal to obtain a fluorine-containing polymer electrolyte (A4). It was.
The obtained A4 was fluorinated in the same manner as in Example 2.
The fluorinated A4 was solubilized in the same manner as in Example 1 to obtain a polymer solution (AS4).
The AS4 was cast to produce a film (AM4) having a thickness of 200 μm. The EW of AM4 was 1049, and the introduction rate of perfluoro1-aza-15-crown-5-ether introduced into the side chain was 10.0 mol%.
Table 1 shows the EW, water content, oxygen solubility and oxygen permeability coefficient of AM4. Table 2 shows the presence or absence of cracks in the catalyst layer using AS4, the battery performance, and the results of the chemical durability test.
AM4 exhibits high oxygen solubility and oxygen permeability coefficient. Further, it can be seen that the catalyst layer using AS4 has no cracks, and the battery performance and chemical durability are higher than those of the comparative material.

(Comparative Example 1)
Using a commercially available Nafion solution (Nafion DE2020CS, manufactured by SIGMA-ALDRICH), a cast film having a thickness of 200 μm was formed in the same manner as in Example 1, and the EW, oxygen solubility and oxygen permeability coefficient were measured. The results are shown in Table 1.
Further, a catalyst layer was prepared using the above Nafion solution in the same manner as in Example 1, and the presence or absence of cracks, battery performance and chemical durability tests were carried out. The results are shown in Table 2.
Nafion DE2020CS has low oxygen solubility. In addition, the catalyst layer is cracked, resulting in low battery performance and chemical durability.

(Comparative Example 2)
Tetrafluoroethylene and _{CF 2 = CFO (CF 2)} 2 perfluorosulfonic acid resin precursor pellets obtained from -SO ₂ F, and dissolved potassium hydroxide (15 wt%) of methyl alcohol (50 wt%) It was hydrolyzed by contacting it in an aqueous solution at 80 ° C. for 20 hours. Then, it was immersed in water at 60 ° C. for 5 hours. Next, the treatment of immersing in a 2N hydrochloric acid aqueous solution at 60 ° C. for 1 hour was repeated 5 times with a new hydrochloric acid aqueous solution, washed with ion-exchanged water, and dried. As a result, pellets of a fluorine-containing polymer electrolyte having a sulfonic acid group (SO _{3 H) were obtained.}
The pellets were placed in a 5 L autoclave together with an aqueous ethanol solution (water: ethanol = 66.7: 33.3 (mass ratio)), sealed, heated to 160 ° C. while stirring with a stirring blade, and held for 5 hours. Then, the autoclave was naturally cooled to prepare a uniform perfluorosulfonic acid resin solution of 5% by mass.
Next, 1200 g of this solution was transferred to a 2 L eggplant flask and placed in a rotary evaporator (BUCHI Rotavapor R-200) in which the hot water bath was set to 80 ° C., and the pressure was reduced so that the solid content concentration became 20% by mass. The mixture was concentrated to prepare a perfluorosulfonic acid resin solution-1.
A cast film having a thickness of 200 μm was formed in the same manner as in Example 1 except that the perfluorosulfonic acid resin solution-1 was used instead of the polymer solution (AS1), and the EW, oxygen solubility and oxygen permeability coefficient were determined. It was measured. The results are shown in Table 1.
Further, a catalyst layer was prepared in the same manner as in Example 1 using the above-mentioned perfluorosulfonic acid resin solution-1, and the presence or absence of cracks, battery performance and chemical durability were tested. The results are shown in Table 2.
The cast membrane using the perfluorosulfonic acid resin solution-1 has low oxygen solubility. In addition, the catalyst layer is cracked, resulting in low battery performance and chemical durability.

(Comparative Example 3)
Cast membrane and perfluorosulfonic acid resin solution-2 as in Comparative Example 2 except that perfluorosulfonic acid resin precursor pellets obtained from tetrafluoroethylene and CF ₂ = CFO (CF ₂ ) _2- SO _{2 F are used.} Got EW, oxygen solubility and oxygen permeability coefficient were measured using cast membranes. The results are shown in Table 1.
Further, a catalyst layer was prepared in the same manner as in Example 1 using the above-mentioned perfluorosulfonic acid resin solution-2, and the presence or absence of cracks, battery performance and chemical durability were tested. The results are shown in Table 2.
The cast membrane using the perfluorosulfonic acid resin solution-2 has low oxygen solubility. In addition, the catalyst layer is cracked, resulting in low battery performance and chemical durability.

(Comparative Example 4)
Copolymer (69.8 mol) of perfluoro (2,2-dimethyl-1,3-dioxol) obtained by radical polymerization method and CF ₂ = CFOCF ₂ CF (CF ₃ ) OCF ₂ CF ₂ SO _{2 F} % / 30.2 mol%) was used, and a cast film and a perfluorosulfonic acid resin solution-3 were obtained in the same manner as in Comparative Example 2. EW, oxygen solubility and oxygen permeability coefficient were measured using cast membranes. The results are shown in Table 1.
Further, a catalyst layer was prepared in the same manner as in Example 1 using the above-mentioned perfluorosulfonic acid resin solution-3, and the presence or absence of cracks, battery performance and chemical durability were tested. The results are shown in Table 2.
The cast membrane using the perfluorosulfonic acid resin solution-3 has higher oxygen solubility as compared with Example 1, but the catalyst layer is cracked, and the battery performance and chemical durability are lowered.

Claims (9)

The side chain has a sulfonyl group as a linking group and / or an ether bond not contained in the ring structure.
At least one of the ether bonds not contained in the sulfonyl group and the ring structure is selected from the group consisting of an aromatic ring, an aliphatic ring, and a complex ring containing an aromatic ring and an aliphatic ring. Is directly connected to
A fluorine-containing polymer electrolyte, wherein the directly bonded cyclic structure contains nitrogen atoms and / or etheric oxygen atoms. The fluorine-containing polymer electrolyte according to claim 1, wherein the sulfonyl group is directly bonded to the nitrogen atom contained in the cyclic structure. The fluorine-containing polymer electrolyte according to claim 1 or 2, wherein the cyclic structure having a direct bond has a substituent containing an ether bond. The fluorine-containing polymer electrolyte according to claim 3, wherein the substituent containing an ether bond is a cyclic ether. The fluorine-containing polymer electrolyte according to any one of claims 1 to 4, which has the structure described in the following formula (1) in the side chain.

(Wherein, NR ₁ is .NR ₁ representing the perfluoro cyclic structure containing a nitrogen atom is a ring structure having 3 to 12 carbon atoms including a nitrogen atom, may have a substituent having 1 to 3 carbon atoms , The substituent may contain an oxygen atom. The NR ₁ may contain an oxygen atom and a nitrogen atom in the perfluoro ring structure.) A fluorinated polymer electrolyte-containing composition comprising the fluorinated polymer electrolyte according to any one of claims 1 to 5, a solvent, and a catalyst. An electrode catalyst layer comprising the fluorine-containing polymer electrolyte-containing composition according to claim 6. A membrane electrode assembly comprising the electrode catalyst layer according to claim 7 and an electrolyte membrane. A fuel cell comprising the membrane electrode assembly according to claim 8.