Electrolyte membranes for membrane electrode assemblies, including fillers that enhance ionic conductivity.

Abstract

Disclosed is an electrolyte membrane for a membrane electrode assembly, which can include a filler that is a polymer compound (oligomer) having a low molecular weight. The electrolyte membrane can suitably include an oligomeric poly(vinylpyrrolidone) compound having a sulfonic acid group. The electrolyte membrane for a membrane electrode assembly can have improved proton conductivity.

Description

TECHNICAL FIELD

[0001] The present invention relates to an electrolyte membrane for a membrane electrode assembly, which includes a filler to improve ionic conductivity. BACKGROUND

[0002] A proton exchange membrane fuel cell (PEMFC) basically includes a fuel electrode (anode), an oxygen electrode (cathode), and a polymer electrolyte membrane disposed between the two electrodes, which is called a membrane electrode assembly.

[0003] Hydrogen as a fuel is supplied to the anode, and oxygen as an oxidizer is supplied to the cathode, and the hydrogen supplied to the anode loses an electron to become a proton (H + ) and moves to the cathode through the polymer electrolyte membrane.

[0004] The electron generated by the hydrogen performs electrical work in the external circuit of the cell and reaches the cathode, and the proton combines with oxygen and an electron to produce water at the cathode.

[0005] For example, the polymer electrolyte membrane can be a representative ion exchange membrane Nafion, which plays a role in transferring the proton generated from the anode to the cathode and serves as a separator to prevent the hydrogen as a fuel from directly contacting the oxygen. In this way, since the proton conduction depends on the proton exchange through the sulfonic acid functional group (-SO3H group) in the presence of water, the degree of hydration of the polymer electrolyte membrane must be maintained at an optimal state.

[0006] Meanwhile, many kinds of inorganic fillers have been studied for the purpose of improving the proton exchange characteristics, i.e., increasing the proton conductivity. TiO2, TiSiO4, SiO2, zeolite, graphene, graphene oxide, etc. are used as fillers for Nafion membranes. In particular, it is known that the inorganic filler improves the proton conductivity while maintaining the membrane hydration in the polymer inorganic composite membrane. However, since the size of the inorganic filler is generally 100 nm, it is 10-100 times the chain length of the Nafion electrolyte membrane or the hydration microstructure thereof. The use of the inorganic filler having such an inappropriate size causes the problem of poor dispersibility in the polymer electrolyte, and as a result, the characteristics of the electrolyte membrane such as mechanical strength can be deteriorated. Therefore, it is very important to use a filler having a proper size suitable for the molecular microstructure of the electrolyte membrane. SUMMARY

[0007] In a preferred aspect, there is provided an electrolyte membrane for a membrane electrode assembly in which the proton conductivity is improved.

[0008] There is also provided an electrolyte membrane for a membrane electrode assembly in which the filler is uniformly dispersed.

[0009] The object of the present application is not limited to the above-described object, and will be clearly understood by the following description, and can be achieved by the means described in the claims and combinations thereof.

[0010] In an aspect, there is provided an electrolyte membrane for a membrane electrode assembly, which can include: an ionomer including a perfluorinated sulfonic acid polymer; and a filler having a weight average molecular weight of about 10,000 g / mol or less and dispersed in the ionomer.

[0011] As used herein, the term "ionomer" refers to a polymeric material or resin including ionized groups attached (e.g., covalently bonded) to a backbone of a polymer as a side group. Preferably, these ionized groups can be functionalized to have ionic properties, such as cationic or anionic properties.

[0012] The ionomer can suitably include one or more polymers selected from the group consisting of fluorine-based polymers, perfluorinated sulfone-based polymers, benzimidazole-based polymers, polyimide-based polymers, polyetherimide-based polymers, polyphenylene sulfide-based polymers, polysulfone-based polymers, polyether sulfone-based polymers, polyether ketone-based polymers, polyether-ether ketone-based polymers, polyphenyl quinoxaline-based polymers, and polystyrene-based polymers.

[0013] As used herein, the term "filler" refers to a material added to a matrix or mixture to improve a property, but does not react or have reactivity with any other compounds or chemicals in the surrounding matrix or mixture. The filler can be in the form of a particle, a fiber, or a resin, preferably, the filler can be a particle.

[0014] In the electrolyte membrane, the filler can have a radius of hydration of about 5 nm or less.

[0015] In the electrolyte membrane, the filler can have a radius of hydration of about 2 nm or less.

[0016] In the electrolyte membrane, the filler can have a weight average molecular weight of about 5,000 g / mol or less.

[0017] The filler can include an oligomer including a repeating unit represented by the following Chemical Formula 1.

[0018] [Chemical Formula 1]

[0019] (M-B)A

[0020] Preferably, M can include one or more selected from the group consisting of: B can include one or more selected from the group consisting of hydrogen (H) and a sulfonic acid group (SO3H), and A can include one or more anions selected from the group consisting of HSO4- , NO3 - , PO4 3- , Cl - , BF4 - , PF6 - , CF3SO3 - , and C2F6NO4S2 - , and M and B can be connected to each other through one or more atoms selected from oxygen (O), nitrogen (N), and sulfur (S) of M.

[0021] The filler can suitably include a poly(vinyl pyrrolidone) (PVP) derivative.

[0022] The filler can suitably include an acid-doped oligomer.

[0023] The filler can suitably include an oligomer represented by the following Chemical Formula 1A.

[0024] [Chemical Formula 1A]

[0025] wherein n is a positive integer, and suitably can be, for example, 1 to 1000 or more, more typically, about 5 or 10 to 100-500.

[0026] The filler can include an oligomer represented by the following Chemical Formula 1B.

[0027] [Chemical Formula 1B]

[0028] wherein n is a positive integer, and suitably can be, for example, 1 to 1000 or more, more typically, about 5 or 10 to 100-500.

[0029] Here, A can include at least one anion selected from the group consisting of HSO4 - , NO3 - , PO4 3- , Cl - , BF4 - , PF6 - , CF3SO3 - , and C2F6NO4S2 - .

[0030] The filler can include at least one selected from the group consisting of compounds represented by the following Chemical Formula 2 to Chemical Formula 9.

[0031] [Chemical Formula 2]

[0032]

[0033] [Chemical Formula 3]

[0034]

[0035] [Chemical Formula 4]

[0036]

[0037] [Chemical Formula 5]

[0038]

[0039] [Chemical Formula 6]

[0040]

[0041] [Chemical Formula 7]

[0042]

[0043] [Chemical Formula 8]

[0044]

[0045] [Chemical Formula 9]

[0046]

[0047] wherein in each of the above Chemical Formula 2 to Chemical Formula 9, n is the same or different positive integer, and can be, for example, 1 to 1000 or more, more typically, about 5 or 10 to 100-500, as appropriate.

[0048] In the electrolyte membrane, the content of the filler can be about 1 to 3 wt% based on the total weight of the electrolyte membrane.

[0049] In one aspect, a method of manufacturing an electrolyte membrane for a membrane electrode assembly is provided, the method comprising: preparing a mixture solution including an ionomer and a filler described herein, the ionomer including a perfluorinated sulfonic acid polymer, for example, the filler having a weight average molecular weight of about 10,000 g / mol or less and being dispersed in the ionomer; applying the mixture on a substrate; and performing a heat treatment on the applied product.

[0050] According to various exemplary embodiments of the present application, an electrolyte membrane for a membrane electrode assembly in which proton conductivity is improved can be obtained.

[0051] Further, according to various exemplary embodiments of the present application, an electrolyte membrane for a membrane electrode assembly in which a filler is uniformly dispersed can be obtained.

[0052] A vehicle, such as an automobile, including a fuel cell comprising a component as disclosed herein is also provided.

[0053] The effects of the present application are not limited to the foregoing, and it should be understood to include all effects that can be reasonably expected from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0054] Figure 1A The illustrated cluster-network model is a molecular microstructure of a hydrated ionomer in a conventional electrolyte membrane;

[0055] Figure 1B The illustrated exemplary cluster-network model is a molecular microstructure of a hydrated ionomer and a filler in an electrolyte membrane according to an exemplary embodiment of the present application; and

[0056] Figure 2 An exemplary manufacturing method of an exemplary electrolyte membrane according to an exemplary embodiment of the present application is illustrated. DETAILED DESCRIPTION

[0057] The above and other objects, features and advantages of the present application will be more clearly understood from the following preferred embodiments taken in conjunction with the accompanying drawings. However, the present application is not limited to the embodiments disclosed herein and can be modified in various ways. These embodiments are provided to fully explain the present application and to fully convey the spirit of the present application to those skilled in the art.

[0058] Throughout the drawings, like reference numerals will be used to designate like or similar elements. For the sake of clarity of the present application, the sizes of structures are depicted larger than the actual sizes thereof. It will be understood that, although terms such as "first" and "second" can be used herein to describe various elements, these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, a "first" element discussed below can be termed a "second" element without departing from the scope of the present application. Similarly, a "second" element can also be termed a "first" element. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0059] It will also be understood that the terms "comprises," "comprising," "includes," "including," "has," "having," and the like, when used in this specification, specify the presence of the stated features, integers, steps, operations, elements, components, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof. It will be understood that when an element or layer is referred to as being "on" another element or layer, it can be directly on the other element or layer or intervening elements or layers can also be present. In contrast, when an element or layer is referred to as being "directly on" another element or layer, there are no intervening elements or layers present. Like numbers refer to like elements throughout.

[0060] Unless otherwise indicated, all numbers, values and / or expressions expressing properties in terms of a single value are to be understood as estimated by the term "about", especially including the inherent variations of the measurement as determined by the equipment used for making the measurement, unless otherwise indicated. All numerical values provided herein are modified by the term "about", unless otherwise specifically indicated.

[0061] Unless specifically stated or otherwise apparent from context, as used herein, the term "about" is understood within normal tolerances of the art, for example within 2 standard deviations of the mean. "About" can be understood to be within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05% or 0.01% of the stated value. Unless otherwise clear from context, all numerical values provided herein are modified by the term "about".

[0062] Further, unless otherwise indicated, when a numerical range is disclosed herein, the range is continuous, and includes all values from the lowest value to the highest value of the range. Further, when the range includes an integer value, unless otherwise indicated, the integer values are included in the range. Further, unless specifically stated otherwise, as used herein, the term "about" is understood within normal tolerances of the art, for example within 2 standard deviations of the mean. "About" can be understood to be within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05% or 0.01% of the stated value. Unless otherwise clear from context, all numerical values provided herein are modified by the term "about".

[0063] The electrolyte membrane for the membrane electrode assembly can include an ionomer including a perfluorinated sulfonic acid polymer and a filler dispersed in the ionomer.

[0064] The ionomer can include a polymer having a proton-conductive functional group. The proton-conductive functional group can include a sulfonic acid, a sulfonic acid salt, a carboxylic acid, a carboxylic acid salt, a phosphoric acid, a phosphoric acid salt, etc. In particular, the ionomer can include a perfluorinated sulfonic acid (PFSA) ionomer containing a proton-conductive functional group. For example, the ionomer can include Nafion.

[0065] Preferably, by adding the filler to the ionomer, the proton conductivity of the electrolyte membrane can be improved.

[0066] For example, according to a cluster-network model, Figure 1A The molecular microstructure of the hydrated ionomer shown, the sulfonic acid group (-SO3 -) absorbed water forms spherical clusters with a diameter of several nanometers, and forms narrow channels of about 1 nm wide connecting the continuous clusters. Therefore, as in the prior art, when a filler with a diameter of about 100 nm, such as TiO2, TiSiO4, SiO2, zeolite, graphene, or graphene oxide, is used, it does not act on the clusters and / or channels, but rather can be agglomerated in the electrolyte membrane or deteriorate the properties, such as the mechanical strength of the electrolyte membrane.

[0067] Therefore, as Figure 1B indicated, for example, by using a filler having a size suitable for the molecular microstructure of the hydrated ionomer molecule, the present application allows the ionomer and the filler to be mixed with each other at the molecular microstructure level.

[0068] Preferably, an acid-doped oligomer or an inherently proton-conductive oligomer can be used as the filler. Therefore, as Figure 1B indicated, when the filler is inserted into the hydrated ionomer clusters, an additional proton path can be provided, and thus the proton conductivity of the electrolyte membrane can be improved.

[0069] The hydrated radius of the filler can be about 5 nm or less, or 2 nm or less. When the hydrated radius of the filler is greater than about 5 nm, it can not be mixed with the molecular microstructure of the hydrated ionomer. On the other hand, the lower limit of the hydrated radius of the filler is not particularly limited, and can be, for example, about 0.1 nm, about 0.5 nm, or about 1 nm.

[0070] The weight average molecular weight of the filler can be about 10,000 g / mol or less, about 5,000 g / mol or less, or about 2,500 g / mol or less. If the weight average molecular weight of the filler is greater than about 10,000 g / mol, the hydrated radius of the filler can be greatly increased, and thus the filler can not be mixed with the molecular microstructure of the hydrated ionomer. On the other hand, the lower limit of the weight average molecular weight of the filler is not particularly limited, and can be, for example, about 500 g / mol or about 1,000 g / mol.

[0071] The filler can include an acid-doped oligomer and / or a proton-conductive oligomer.

[0072] An acid-doped oligomer can be obtained by acid treatment of an oligomer having an unsaturated coordination site of nitrogen or sulfur. In particular, the acid-doped oligomer can include an oligomer containing a repeating unit represented by Chemical Formula 1 below.

[0073] [Chemical Formula 1]

[0074] (M-B)A

[0075] M is a polymer repeating unit having an unsaturated coordination site of nitrogen or sulfur, which is a matrix of the acid-doped oligomer, and preferably can include one or more selected from the group consisting of:

[0076]

[0077] Also, B and A are those due to the acid used, B can include one or more of hydrogen (H) and sulfonic acid group (SO3H), and A can include one or more anions selected from the group consisting of HSO4 - , NO3 - , PO4 3- , Cl - , BF4 - , PF6 - , CF3SO3 - , and C2F6NO4S2 - .

[0078] M and B can be connected to each other by one or more atoms selected from the group consisting of oxygen (O), nitrogen (N), and sulfur (S) of M.

[0079] More particularly, the acid-doped oligomer can include an oligomer represented by Chemical Formula 1A or Chemical Formula 1B below.

[0080] [Chemical Formula 1A]

[0081]

[0082] [Chemical Formula 1B]

[0083]

[0084] In Chemical Formula 1A and Chemical Formula 1B, n can be a value suitable for the weight average molecular weight of the above-described filler, and A of Chemical Formula 1B is as described above. Preferably, n is a positive integer, and can be, for example, 1 to 1000 or more, more typically, about 5 or 10 to 100-500, as appropriate.

[0085] The compound of Chemical Formula 1A and Chemical Formula 1B can be an oligomer obtained by treating poly(vinylpyrrolidone) (PVP) with an acid, the above-described poly(vinylpyrrolidone) being a polymer having an unsaturated coordination site of nitrogen or sulfur.

[0086] The poly(vinylpyrrolidone) can be a biocompatible polymer, which is hygroscopic, easily soluble in water and alcohol, non-toxic, and does not cause irritation. The poly(vinylpyrrolidone) can have a polarity of amide (RC(=O)NR’R”). For example, the poly(vinylpyrrolidone) has high compatibility with other polar polymers, and thus can be widely used as an additive.

[0087] The results of measurements of the hydrodynamic radius of poly(vinylpyrrolidone) depending on its weight average molecular weight measured by dynamic light scattering (DLS) and gel permeation chromatography (GPC), and the results of measurements of the radius of gyration (Rg) of the polymer chain of poly(vinylpyrrolidone) measured using a multi-angle light scattering (MALS) device are shown in Table 1 below.

[0088] Table 1

[0089]

[0090] 1) 18 angles were used;

[0091] 2) Not measured because the particles were too small

[0092] It can be desirable to prepare the filler by acid treatment of poly(vinylpyrrolidone) having a weight average molecular weight of about 10,000 g / mol or less, taking into account the diameter of the hydration shell of the ionomer.

[0093] The reaction scheme for obtaining the oligomer of Formula 1A by acid treatment of poly(vinylpyrrolidone) is as follows.

[0094]

[0095] The reaction scheme for obtaining the oligomer of Formula 1B by acid treatment of poly(vinylpyrrolidone) is as follows.

[0096]

[0097] For example, an acid such as sulfuric acid, nitric acid, phosphoric acid, hydrochloric acid, HBF4, HPF6, HCF3SO3, HC2F6NO4S2, and the like is added to a PVP aqueous solution, stirred, and then precipitated with an acetone solvent or the like, and then centrifuged to obtain a gel-like product. The product thus obtained is dried in an oven, thereby producing the oligomer of Formula 1B.

[0098] The filler can suitably include an intrinsic proton-conducting oligomer.

[0099] The proton-conducting oligomer can suitably include one or more selected from the group consisting of compounds represented by Formulae 2 to 9.

[0100] [Formula 2]

[0101]

[0102] [Formula 3]

[0103]

[0104] [Formula 4]

[0105]

[0106] [Chemical Formula 5]

[0107]

[0108] [Chemical Formula 6]

[0109]

[0110] [Chemical Formula 7]

[0111]

[0112] [Chemical Formula 8]

[0113]

[0114] [Chemical Formula 9]

[0115]

[0116] n is a positive integer and can be, for example, 1 to 1000 or more, more typically, about 5 or 10 to 100-500, as appropriate.

[0117] The content of the filler can be about 1 to 5 wt%, or 1 to 3 wt%, based on the total weight of the electrolyte membrane. When the content thereof is less than about 1 wt%, the effect of improving the proton conductivity can become insignificant, and when the amount thereof is greater than about 5 wt%, the dispersibility of the filler in the ionomer can decrease.

[0118] Figure 2 An exemplary manufacturing method for an exemplary electrolyte membrane for an exemplary membrane electrode assembly according to an exemplary embodiment of the present application is shown. Referring to Figure 2 , the method of the present application includes preparing a mixture including an ionomer (including a perfluorinated sulfonic acid polymer) and a filler (S10), applying the mixture on a substrate such as a release paper or the like (S20), and performing a heat treatment on the applied product (S30).

[0119] The ionomer and the filler are as described above, and thus a detailed description thereof is omitted.

[0120] The method of applying the mixture is not particularly limited. Examples thereof can include a screen-printing process, a spray coating process, a coating process using a doctor blade, a gravure coating process, a dip coating process, a silkscreen process, a painting process, and a coating process using a slot die.

[0121] After the mixture is applied to the substrate, the method can further include performing drying. The drying can be performed at a temperature of about 100°C or less for about 30 minutes or more. When the drying temperature is greater than about 100°C, the ionomer can be thermally decomposed. Meanwhile, when the drying time is less than about 30 minutes, the drying can not be properly performed.

[0122] The heat treatment can be performed at a temperature of about 110°C or more for about 20 minutes or less. When the heat treatment time is too long, the ionomer can be thermally decomposed.

[0123] Examples

[0124] The present application will be better understood by the following examples, which are presented only for the purpose of illustration and do not constitute a limitation on the scope of the present application.

[0125] Preparation Example 1

[0126] An acid-doped oligomer represented by Chemical Formula 1A was prepared by subjecting poly(vinylpyrrolidone) having a weight average molecular weight of 2,500 g / mol to acid treatment according to the method disclosed in HR Safaei et al., RSC Adv., 2015, 5, 6797.

[0127] Preparation Example 2

[0128] An aqueous solution having 10 wt% of poly(vinylpyrrolidone) having a weight average molecular weight of 2,500 g / mol was prepared. The aqueous solution was placed in an ice bath, and a diluted aqueous sulfuric acid solution containing 50 wt% sulfuric acid was added dropwise to the aqueous solution and stirred, followed by precipitation using an acetone solvent, and then centrifugation, to obtain a gel-like product. The product thus obtained was dried in a vacuum oven for about 12 hours, thereby producing an acid-doped oligomer represented by Chemical Formula 1B (wherein A is HSO4 - ).

[0129] Example 1

[0130] Nafion was used as the ionomer, and the acid-doped oligomer obtained in Preparation Example 1 was used as the filler.

[0131] A mixture of the ionomer and the filler was prepared, in which the amount of the filler was 1 wt%, 3 wt%, and 5 wt% based on the total weight of the mixture.

[0132] The mixture was applied to one side of a release paper, dried, and heat-treated, thereby manufacturing an electrolyte membrane.

[0133] Example 2

[0134] An electrolyte membrane was produced in the same manner as in Example 1, except that the acid-doped oligomer obtained in Preparation Example 2 was used as a filler.

[0135] Comparative Example

[0136] An electrolyte membrane was produced in the same manner as in Example 1, except that poly(vinylpyrrolidone) (weight average molecular weight: 2,500 g / mol) not subjected to acid treatment was used as a filler.

[0137] Test Example - Measurement of Proton Conductivity

[0138] The proton conductivities of the electrolyte membranes of Example 1, Example 2, and Comparative Examples were measured. Specifically, the proton conductivities were measured in the in-plane direction of the electrolyte membranes at a temperature of about 80°C and a relative humidity of about 50%. The results thereof are shown in Table 2 below.

[0139] Table 2

[0140]

[0141] 1) The electrolyte membrane was not added with a filler

[0142] Referring to Table 2, in the comparative examples, it can be seen that the filler acts as a material that hinders proton conduction, and thus, the proton conductivity decreases as the amount of the filler increases.

[0143] From the results of Example 1 and Example 2 in which the acid-doped oligomer was used as a filler, it is apparent that there is no great difference between them. In addition, in Example 1 and Example 2, the proton conductivity was maximally increased by about 10 mS / cm compared to the case of the electrolyte membrane to which no filler was added, and the proton conductivity was maximally increased by about 30 mS / cm compared to the comparative examples.

[0144] The present application has been described in detail with respect to test examples and various exemplary embodiments. However, the scope of the present application is not limited to the above-described test examples and embodiments, and various modifications and improved modes of the present application using the basic concept of the present application defined in the appended claims are also incorporated into the scope of the present application.

Claims

1. An electrolyte membrane for a membrane electrode assembly, comprising: a ionomer comprising a perfluorinated sulfonic acid polymer; and a filler having a weight average molecular weight of 10,000 g / mol or less and dispersed in the ionomer, wherein the filler comprises an acid-doped oligomer, and which comprises a repeating unit represented by the following Chemical Formula 1: [Chemical Formula 1] (M-B)A wherein M comprises B comprises one or more selected from hydrogen H and a sulfonic acid group SO3H, A comprises one or more anions selected from the group consisting of HSO4 - , NO3 - , PO4 3- , CI - , BF4 - , PF6 - , CF3SO3 - , and C2F6NO4S2 - , and M and B are connected to each other through one or more atoms selected from oxygen O and nitrogen N of M, wherein the filler is inserted into a hydrated ionomer cluster, and the electrolyte membrane comprises the filler in an amount of 1 wt% to 3 wt% based on the total weight of the electrolyte membrane, wherein the filler comprises a poly(vinyl pyrrolidone) PVP derivative.

2. The electrolyte membrane according to claim 1, wherein the filler has a hydrated radius of 5 nm or less.

3. The electrolyte membrane according to claim 1, wherein the filler has a hydrated radius of 2 nm or less.

4. The electrolyte membrane according to claim 1, wherein the filler has a weight average molecular weight of 5,000 g / mol or less.

5. The electrolyte membrane according to claim 1, wherein the filler comprises an oligomer represented by the following Chemical Formula 1A: [Chemical Formula 1A] where n is a positive integer.

6. The electrolyte membrane according to claim 1, wherein the filler comprises an oligomer represented by the following Chemical Formula 1B: [Chemical Formula 1B] wherein A comprises one or more anions selected from the group consisting of HSO4 - , NO3 - , PO4 3- , Cl - , BF4 - , PF6 - , CF3SO3 - , and C2F6NO4S2 - ; n is a positive integer.

7. A method of manufacturing an electrolyte membrane for a membrane electrode assembly according to any one of claims 1 to 6, comprising the steps of: preparing a mixture comprising an ionomer comprising a perfluorinated sulfonic acid polymer and a filler having a weight average molecular weight of 10,000 g / mol or less and dispersed in the ionomer; applying the mixture on a substrate; and subjecting the applied product to a heat treatment.

8. A membrane electrode assembly, comprising: the electrolyte membrane according to any one of claims 1 to 6; a cathode formed on one side of the electrolyte membrane; and an anode formed on the remaining side of the electrolyte membrane.

9. A fuel cell comprising the membrane electrode assembly according to claim 8.

10. A vehicle comprising the fuel cell according to claim 9. ​ ​

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