Hydrocarbon membrane

Abstract

This disclosure provides a process for preparing an ion-conducting membrane containing a sulfonated hydrocarbon ionomer having an ion exchange capacity of I2meq / g, the process comprising the following steps: The process includes: a) providing a sulfonated hydrocarbon ionomer having an ion exchange capacity of I1meq / g; b) casting an ion-conducting membrane from a mixture of the sulfonated hydrocarbon ionomer provided in step a) and a solvent; and c) applying a treatment to the ion-conducting membrane prepared in step b) to reduce its ion exchange capacity from I1meq / g to I2meq / g (where I2 is less than I1).

Description

[Technical Field]

[0001] This disclosure relates to ion-conducting membranes containing sulfonated hydrocarbon ionomers and methods for preparing the same. Specifically, this disclosure relates to proton exchange membranes and processes for producing the same. Ion-conducting membranes may be suitable for use in electrochemical devices such as fuel cells and / or electrolytic devices. [Background technology]

[0002] A fuel cell is an electrochemical cell containing two electrodes separated by an electrolyte. A fuel, such as hydrogen, an alcohol like methanol or ethanol, or formic acid, is supplied to the anode, and an oxidizer, such as oxygen or air, is supplied to the cathode. An electrochemical reaction occurs at the electrodes, converting the chemical energy of the fuel and oxidizer into electrical energy and heat. Electrode catalysts are used to facilitate the electrochemical oxidation of the fuel at the anode and the electrochemical reduction of oxygen at the cathode.

[0003] Fuel cells are typically classified according to the properties of the electrolyte used. In many cases, the electrolyte is a solid polymer membrane, which is electronically insulating but ionically conductive. In a proton exchange membrane fuel cell (PEMFC), the membrane is proton conductive, and protons generated at the anode are transported across the membrane to the cathode, where they combine with oxygen to form water.

[0004] An electrolyzer is an electrochemical device used to produce high-purity hydrogen and oxygen by electrolyzing water. Electrolyzers can operate in both alkaline and acidic systems. Those using solid proton-conducting polymer electrolyte membranes or proton exchange membranes (PEMs) are known as proton exchange membrane water electrolyzers (PEMWEs).

[0005] Traditionally, perfluorosulfonic acid (PFSA) ionomers have been used in proton exchange membranes due to their favorable properties, proven over many years in terms of membrane performance, durability, and manufacturability. However, due to environmental concerns, for example, regarding fluorinated chemicals, hydrocarbon ionomers are being actively sought as alternatives to PFSA ionomers.

[0006] Many different hydrocarbon ionomers have been studied, with a focus on ionomers that incorporate aromatic groups as part of the polymer backbone, such as poly(arylene ether), poly(arylene ether ketone), poly(arylene sulfone), poly(imide), poly(benzimidazole), polyphenylene, and sulfonated derivatives of phenylated polyphenylene. However, films made from hydrocarbon ionomers have not met the performance and manufacturability standards required for commercial film products. In particular, hydrocarbon ionomers consistently exhibit lower dispersion limits and a narrower range of suitable casting solvents compared to current PFSA products. [Overview of the project]

[0007] Therefore, this disclosure provides a process for preparing an ion-conducting membrane containing a sulfonated hydrocarbon ionomer having an ion exchange capacity of I2meq / g, the process comprising the following steps: a) A step of providing a sulfonated hydrocarbon ionomer having an ion exchange capacity of I1meq / g, b) A step of casting an ion-conducting film from a mixture of the sulfonated hydrocarbon ionomer provided in step a) and a solvent, c) A step of applying a treatment to the ion-conducting membrane prepared in step b) to reduce the ion exchange capacity from I1meq / g to I2meq / g (where I2 is less than I1).

[0008] The identity of the sulfonated hydrocarbon ionomer remains the same throughout the process, except for a decrease in ion exchange capacity corresponding to a decrease in the amount of sulfonate groups in the hydrocarbon ionomer.

[0009] The inventors have found that ionomers with higher ion exchange capacity are more processable and can be cast more easily to form films. However, ionomers with lower ion exchange capacity are often desirable for ion-conducting films. Surprisingly, after fabricating an ion-conducting film using such a high ion exchange capacity ionomer, it is possible to reduce the ion exchange capacity without damaging the film, thereby improving its durability. Therefore, effective hydrocarbon ionomer films can be prepared by conventional film casting techniques that are easy to implement.

[0010] This disclosure also relates to a process for preparing a catalyst coating film for a fuel cell or water electrolysis device, wherein the catalyst coating film comprises a catalyst layer on the surface of an ion-conducting film, and the process is as follows: i) Preparing an ion-conducting film by a process defined in this disclosure, ii) Preparing the catalyst layer, Includes, The invention also provides a process in which the catalyst layer is prepared and the ion-conducting film is applied to the catalyst layer, or the ion-conducting film is prepared and the catalyst layer is applied to the ion-conducting film.

[0011] The advantageous process of this disclosure is particularly suitable for so-called addition-layer processes for preparing catalyst coatings, in which the catalyst coating is constructed layer by layer. It is also particularly suitable for direct-to-membrane printing of the catalyst layer. [Brief explanation of the drawing]

[0012] [Figure 1] The FT-IR spectra comparing an ion-conductive film that has undergone treatment step c) as defined herein with an ion-conductive film that has not undergone treatment are shown. [Figure 2] This chart shows the decrease in water uptake of the ion-conducting membrane after undergoing treatment step c) as defined herein. [Figure 3] This chart shows the further reduction in water uptake of the ion-conducting membrane after undergoing treatment step c) as defined herein. [Figure 4] This chart shows the reduction in dimensional change from a dry state to a wet state of an ion-conducting film after undergoing processing step c) as defined herein. [Figure 5] This chart shows the reduction in dimensional change from a dry state to a wet state of the ion-conducting film after undergoing processing step c) as defined herein. [Figure 6] Figures 3 and 5 show charts of data relating to the rate of change in mass and the rate of change in the in-plane (x) dimension. [Figure 7] This chart shows the ion exchange capacity of the ion-conducting membrane after undergoing processing step c) as defined herein. [Figure 8] This chart correlates the ion exchange capacity after processing step c) as defined herein with the dimensional change from a dry state to a wet state. [Figure 9] This chart, based on thermogravimetric analysis data, shows the mass loss process resulting from water loss and sulfonate group loss in sulfonated hydrocarbon ionomers undergoing heat treatment. [Figure 10] This chart, based on thermogravimetric analysis data, shows the mass loss process resulting from water loss and sulfonate group loss in sulfonated hydrocarbon ionomers undergoing heat treatment. [Modes for carrying out the invention]

[0013] Therefore, the ion-conducting membrane is a hydrocarbon membrane, i.e., it does not contain a fluorinated ionomer. An ionomer is a polymer composed of both electrically neutral repeating units and ionizing units covalently bonded to the electrically neutral repeating units as a pendant portion. In a hydrocarbon ionomer, the electrically neutral repeating units are hydrocarbon-based and do not contain fluorine substituents. In a sulfonated hydrocarbon ionomer, the ionizing units are sulfonate moieties. Preferably, the sulfonated hydrocarbon ionomer is selected from sulfonated derivatives of poly(arylene ether), poly(arylene ether ketone), poly(arylene sulfone), poly(imide), poly(benzimidazole), polyphenylene, and phenylated polyphenylene. Typically, the sulfonated hydrocarbon ionomer is a sulfonated polyphenylene hydrocarbon ionomer. Sulfonated polyphenylene hydrocarbon ionomers include straight-chain sulfonated polyphenylenes, kinked sulfonated polyphenylenes, side-chain sulfonated polyphenylenes, or sulfonated phenylated polyphenylene hydrocarbon ionomers. Such motifs are known to those skilled in the art, as described, for example, in “On the evolution of sulfonated polyphenylenes as proton exchange membranes for fuel cells”, Mater. Adv. 2021, 2, pp 4966-5005. More typically, sulfonated hydrocarbon ionomers include sulfonated phenylated polyphenylene hydrocarbon ionomers, such as the Pemion® series of sulfonated hydrocarbon ionomers from Ionomr Innovations. Sulfonated phenylated polyphenylene hydrocarbon ionomers can be straight-chain or branched-chain.

[0014] Sulfonated phenylated polyphenylene hydrocarbon ionomers typically comprise a core repeating unit containing a sulfonated moiety with at least three aryl and / or heteroaryl groups linked by carbon-carbon single bonds. Typically, the core repeating unit contains 10 or fewer, more typically 9 or fewer, aryl and / or heteroaryl groups. Typically, the core repeating unit contains at least five aryl and / or heteroaryl groups. The core repeating unit may contain nine aryl and / or heteroaryl groups and can be obtained by a cycloaddition reaction of a sulfonated bistetracyclone moiety with diphenylacetylene, for example, as described in Mater.Adv.2021,2,pp 4966-5005 and “Structurely-Defined, Sulfo-Phenylated, Oligophenylenes and Polyphenylenes”, J.Am.Chem.Soc.,2015,137,pp12223-12226, and International Publication No. 2018 / 187864, which is incorporated herein by reference in its entirety. The repeating unit may further contain linking groups containing heteroaryl and / or aryl groups, typically at least one, up to 10, and more typically up to 7 such groups. Preferably, the linking groups contain one or more phenyl groups, typically only phenyl groups. Preferably, the linking groups contain one or more naphthyl groups. Preferably, the linking group contains one or more pyridyl groups.

[0015] The sulfonated phenylated polyphenylene hydrocarbon ionomer may also include a core hydrophobic repeating unit that does not contain a sulfonate moiety and may contain at least three aryl and / or heteroaryl groups linked by carbon-carbon single bonds. Typically, the core repeating unit contains 10 or fewer, more typically 9 or fewer aryl and / or heteroaryl groups. Typically, the core repeating unit contains at least 5 aryl and / or heteroaryl groups. The core repeating unit may contain 9 aryl and / or heteroaryl groups and may be obtained, for example, by a cycloaddition reaction of a bistetracyclone moiety with diphenylacetylene, as described in International Publication 2018 / 187864, which is incorporated herein by reference in its entirety. This hydrophobic repeating unit may further contain linking groups containing heteroaryl and / or aryl groups, typically at least 1, 10 or fewer, more typically 7 or fewer such groups. Preferably, the linking groups contain one or more phenyl groups, typically only phenyl groups. Preferably, the linking group contains one or more naphthyl groups. Preferably, the linking group contains one or more pyridyl groups.

[0016] The molar ratio of repeating units containing sulfonated moieties to hydrophobic repeating units may be in the range of approximately 1:99 to approximately 99:1 (including both ends). The sulfonated hydrocarbon ionomer may be a block copolymer comprising a first block having repeating units containing the sulfonated moieties defined above, and a second block having a second repeating unit containing the hydrophobic repeating units defined above. The number of repeating units containing sulfonated moieties in the first block may be in the range of approximately 3 to approximately 100 (including both ends), and the number of repeating units containing hydrophobic repeating units in the second block may be in the range of approximately 3 to approximately 100 (including both ends).

[0017] The sulfonated hydrocarbon ionomer provided in step a) has an ion exchange capacity of I1meq / g. The hydrocarbon ionomer provided in step a) has more sulfonate groups than the hydrocarbon ionomer in the ion-conducting film after step c) of the process. Therefore, it contains sacrificial sulfonate groups and can be removed by a treatment, which is preferably a heat treatment step as defined herein. In other words, the ionomer provided in step a) having an ion exchange capacity of I1meq / g is reduced to I2meq / g by the treatment, and this reduction in ion exchange capacity is caused by the treatment. The sacrificial sulfonate groups may be bonded to the hydrocarbon ionomer by carbon-sulfur bonds, as in the conventional method. For example, in phenylated polyphenylene hydrocarbon ionomers, the sulfonate groups may be bonded to the phenyl groups by carbon-sulfur bonds. The temperature required for thermal decomposition can be varied, for example, by adding specific counterions (e.g., Na, Ca counterions). Alternatively, the sulfonate groups may be bonded to the hydrocarbon ionomer via linking groups that facilitate the removal of the sulfonate groups by treatment, preferably by heat treatment. Alternative treatments may include, for example, UV curing (photodegradation), oxidation, hydrolysis, thermal decomposition, or biodegradation. The number of sulfonate groups in the hydrocarbon ionomer provided in step a) can be controlled by the synthetic process used to prepare the hydrocarbon ionomer, for example, by using a synthetic precursor having an appropriate level of sulfonation. For example, the level of sulfonation in the precursor used to produce phenylated polyphenylene hydrocarbons in a process such as that disclosed in whole by reference in International Publication No. 2018 / 187864 and “On the evolution of sulfonated polyphenylenes as proton exchange membranes for fuel cells”, Mater. Adv. 2021, 2, pp 4966-5005. I1 may preferably be about 4 meq / g or more, preferably about 5 meq / g or more, and typically about 7 meq / g or more.I1 can be any value, preferably greater than I2, that provides an ionomer that can be processed under desired conditions, for example, one that can be effectively mixed with and cast from a desired solvent. The treatment in step c) is typically a heat treatment, which can be carried out by any preferred method, for example, using a hot oven. Such a heat treatment is carried out at a temperature and time that reduces the ion exchange capacity to a desired level, which can be quantified by those skilled in the art using the methods disclosed herein. Thus, the treatment in step b) is an effective treatment for reducing I1 to I2. As an example, the heat treatment may include applying a temperature above about 140°C, preferably above about 160°C, for example, a temperature above about 180°C. The temperature is typically below about 330°C, preferably below about 260°C, typically below about 230°C. The heat treatment may be carried out for a time ranging from about 1 minute to about 20 minutes, preferably about 2 minutes to about 18 minutes, and typically about 4 minutes to about 14 minutes. I2 may typically be about 4 meq / g or less, preferably about 3.5 meq / g or less, for example, about 3 meq / g or less. I2 may typically be about 1 meq / g or more, and typically about 2 meq / g or more. The ion exchange capacity can be measured using titration. For example, in acid form (H. + The membrane was immersed in a 1.0 M NaCl solution for 24 hours and then H + Ions Na + It can be converted to the sodium salt form by exchange with ions. Then, the exchanged H in solution + The ions can be titrated with a 0.02 N NaOH solution. The theoretical ion exchange capacity, calculated from the degree of sulfonation, can be obtained from the formula: Ion exchange capacity (meq / g) = Ionic mmol concentration / Mass of the dry film at 25°C.

[0018] The sulfonated hydrocarbon ionomer preferably has a repeating unit of formula (I):

[0019] [ka] [In the formula, R 1A, R 1B , R 1C , R 1D , R 1E and R 1F are, independently, aryl or heteroaryl, each optionally substituted by 1, 2, 3, 4 or 5 substituents independently selected from C 1~6 alkyl, halo, nitro, cyano, and SO3 - X + (X + is H + or a cation), provided that at least two of R 1A , R 1B , R 1C , R 1D , R 1E and R 1F are, independently, aryl or heteroaryl, each optionally substituted by 1, 2, 3, 4 or 5 SO3 - X + substituents, R 1G and R 1H are, independently, H, aryl, or heteroaryl, the aryl and heteroaryl each optionally substituted by 1, 2, 3, 4 or 5 substituents independently selected from C 1~6 alkyl, halo, nitro, cyano, and SO3 - X + (X + ​​​​​​​​​​​​L1 is a optionally substituted linked heteroatom, arylene, heteroarylene, aralkylene, or heteroaralkylene, where each of the arylene, heteroarylene, aralkylene, and heteroaralkylene is C 1~6 Optionally substituted with 1, 2, 3, or 4 substituents independently selected from alkyl, halo, nitro, cyano, aryl, and heteroaryl groups, L2 is either absent or is arylene or heteroarylene, and such arylene and heteroarylene are C 1~6 Optionally substituted with 1, 2, 3, or 4 substituents independently selected from alkyl, halo, nitro, cyano, aryl, and heteroaryl groups, L3 is either absent or is an arylene or heteroarylene, and such arylene and heteroarylene are C 1~6 Optionally substituted with 1, 2, 3, or 4 substituents independently selected from alkyl, halo, nitro, cyano, aryl, and heteroaryl groups, R 1G and R 1H [This can independently include H].

[0020] The repeating unit of formula (I) is preferably formula (IA):

[0021] [ka] [In the formula, R 1A , R 1B , R 1C , R 1D , R 1E and R 1F These are independently aryl or heteroaryl, and each is C 1~6 Alkyl, halo, nitro, cyano, and SO3 - X + (X + H + Optionally substituted with 1, 2, 3, 4, or 5 substituents independently selected from (or cations), provided that R 1A , R 1B, R 1C , R 1D , R 1E and R 1F At least two of these are independently aryl or heteroaryl, each containing 1, 2, 3, 4, or 5 SO3 molecules. - X + Optionally substituted by substituents, R 2A , R 2B , R 2C , R 2D These are independently H, halo, nitro, cyano, aryl, or heteroaryl, L1 is a optionally substituted linked heteroatom, arylene, heteroarylene, aralkylene, or heteroaralkylene, where each of the arylene, heteroarylene, aralkylene, and heteroaralkylene is C 1~6 Optionally substituted with 1, 2, 3, or 4 substituents independently selected from alkyl, halo, nitro, cyano, aryl, and heteroaryl groups, L2 is either absent or is arylene or heteroarylene, and such arylene and heteroarylene are C 1~6 Optionally substituted with 1, 2, 3, or 4 substituents independently selected from alkyl, halo, nitro, cyano, aryl, and heteroaryl groups, L3 is either absent or is an arylene or heteroarylene, and such arylene and heteroarylene are C 1~6 It may be a repeating unit [optionally substituted with 1, 2, 3, or 4 substituents independently selected from alkyl, halo, nitro, cyano, aryl, and heteroaryl groups].

[0022] R 1A , R 1B , R 1C , R 1D , R 1E and R 1F These may independently be aryl or heteroaryl, each containing 1, 2, 3, 4, or 5 SO3 molecules. - X + (X + H +or optionally substituted by a cation), provided that R 1A , R 1B , R 1C , R 1D , R 1E and R 1F at least two of which are independently aryl or heteroaryl substituted with 1, 2, 3, 4 or 5 SO 3- X + . R 1A , R 1B , R 1C , R 1D , R 1E and R 1F may each independently be aryl, optionally substituted by 1, 2, 3, 4 or 5 SO 3- X + (X + is H + or a cation), provided that R 1A , R 1B , R 1C , R 1D , R 1E and R 1F at least two of which are independently phenyl substituted with 1, 2, 3, 4 or 5 SO 3- X + . R 1A , R 1B , R 1C , R 1D , R 1E and R 1F may each independently be phenyl, optionally substituted by 1, 2, 3, 4 or 5 SO 3- X + (X + is H + [[ID=​​​​​​​​​​​​​​​​​​​​​​+ or [N(R 5A )(R 5B )(R 5C )(R 5D )] + And may be a cation selected from alkali metal ions, R 5A , R 5B , R 5C , R 5D H and C are independent of each other. 1~6 It is alkyl, aryl, or heteroaryl.

[0024] A1 may be an arylene optionally substituted with 1, 2, 3, 4, or 5 substituents independently selected from halo, nitro, cyano, aryl, and heteroaryl groups. A2 may be absent. Alternatively, A2 may be an arylene optionally substituted with 1, 2, 3, 4, or 5 substituents independently selected from halo, nitro, cyano, aryl, and heteroaryl groups.

[0025] R 2A , R 2B , R 2C , R 2D These can be H or halo independently. Typically, R 2A , R 2B , R 2C , R 2D Each of these is H.

[0026] L1 may be arylene or heteroarylene, and each is C 1~6 It is optionally substituted with 1, 2, 3, or 4 substituents independently selected from alkyl, halo, aryl, and heteroaryl groups. Preferably, L1 is arylene or heteroarylene, each being C 1~6 It is optionally substituted with 1, 2, 3, or 4 substituents independently selected from alkyl and halo. Typically, L1 is an arylene or heteroarylene, and 1, 2, 3, or 4 C substituents. 1~6 It is optionally substituted with an alkyl group. Typically, L1 is an arylene or heteroarylene. Preferably, L1 is C 1~6The arylene is optionally substituted with 1, 2, 3, or 4 substituents independently selected from alkyl and halo. Typically, L1 is 1, 2, 3, or 4 C 1~6 It is an arylene optionally substituted with an alkyl group. Typically, L1 is an arylene. L1 is naphthalene, phenylene, or C 1~6 It may be alkyl-substituted phenylene. Preferably, L1 is phenylene or C 1~6 It is alkyl-substituted phenylene.

[0027] L2 may be absent. Alternatively, L2 may be an arylene or a heteroarylene, and the arylene and heteroarylene are each C 1~6 L2 may be optionally substituted with 1, 2, 3, or 4 substituents independently selected from alkyl and halo. L2 may be an arylene or a heteroarylene, and the arylene and heteroarylene each have 1, 2, 3, or 4 C substituents. 1~6 It is optionally substituted with an alkyl group. L2 may be an arylene or a heteroarylene. L2 may be an arylene, and the arylene is C 1~6 L2 may be optionally substituted with 1, 2, 3, or 4 substituents independently selected from alkyl and halo. L2 may be an arylene, which has 1, 2, 3, or 4 C substituents. 1~6 It is optionally substituted with an alkyl group. L2 may be arylene. L2 may be phenylene.

[0028] L3 may not be present. Alternatively, L3 may be an arylene or a heteroarylene, and the arylene and heteroarylene are each C 1~6 L3 is optionally substituted with 1, 2, 3, or 4 substituents independently selected from alkyl and halo. L3 may be an arylene or a heteroarylene, and the arylene and heteroarylene each have 1, 2, 3, or 4 C substituents. 1~6It is optionally substituted with an alkyl group. L3 may be an arylene or a heteroarylene. L3 may be an arylene, and the arylene is C 1~6 L3 may be optionally substituted with 1, 2, 3, or 4 substituents independently selected from alkyl and halo. L3 may be an arylene, which has 1, 2, 3, or 4 C substituents. 1~6 It is optionally substituted with an alkyl group. L3 may be arylene. L3 may be phenylene.

[0029] Formula (I) is preferably formula (IB):

[0030] [ka] (In the formula, -L3-L2-L1- is,

[0031] [ka]

[0032] [ka] It can be a repeating unit of (which can be selected from).

[0033] The sulfonated hydrocarbon ionomer is preferably of formula (II):

[0034] [ka] (In the formula, R 3A , R 3B , R 3C , R 3D , R 3E and R 3F These are independently aryl or heteroaryl, and each is C 1~6 Optionally substituted with 1, 2, 3, 4, or 5 substituents independently selected from alkyl, halo, nitro, and cyano, R 3Gand R 3H These are independently H, aryl, or heteroaryl, and the aryl and heteroaryl are each C 1~6 Optionally substituted with 1, 2, 3, 4, or 5 substituents independently selected from alkyl, halo, nitro, and cyano, typically R 3G and R 3H H is independent of H, B1 is an arylene, heteroarylene, aralkylene, or heteroalkylene, each optionally substituted with 1, 2, 3, or 4 substituents independently selected from halo, nitro, cyano, aryl, and heteroaryl. B2 is either absent or is an arylene or heteroarylene, and each arylene and heteroarylene is optionally substituted with 1, 2, 3, or 4 substituents independently selected from halo, nitro, cyano, aryl, and heteroaryl. K1 is a optionally substituted linked heteroatom, arylene, heteroarylene, aralkylene, or heteroaralkylene, where each of the arylene, heteroarylene, aralkylene, and heteroaralkylene is C 1~6 Optionally substituted with 1, 2, 3, or 4 substituents independently selected from alkyl, halo, nitro, cyano, aryl, and heteroaryl groups, K2 is either absent or is an arylene or heteroarylene, and such arylene and heteroarylene are each C 1~6 Optionally substituted with 1, 2, 3, or 4 substituents independently selected from alkyl, halo, nitro, cyano, aryl, and heteroaryl groups, K3 is either absent or is an arylene or heteroarylene, and such arylene and heteroarylene are each C 1~6 The hydrophobic repeating units may also include those optionally substituted with 1, 2, 3, or 4 substituents independently selected from alkyl, halo, nitro, cyano, aryl, and heteroaryl groups.

[0035] The repeating unit of formula (II) is preferably formula (II-A):

[0036] [ka] (In the formula, R 3A , R 3B , R 3C , R 3D , R 3E and R 3F These are independently aryl or heteroaryl, and each is C 1~6 Optionally substituted with 1, 2, 3, 4, or 5 substituents independently selected from alkyl, halo, nitro, and cyano, R 4A , R 4B , R 4C , R 4D These are independently H, halo, nitro, cyano, aryl, or heteroaryl. K1 is a optionally substituted linked heteroatom, arylene, heteroarylene, aralkylene, or heteroaralkylene, where each of the arylene, heteroarylene, aralkylene, and heteroaralkylene is C 1~6 Optionally substituted with 1, 2, 3, or 4 substituents independently selected from alkyl, halo, nitro, cyano, aryl, and heteroaryl groups, K2 is either absent or is an arylene or heteroarylene, and such arylene and heteroarylene are each C 1~6 Optionally substituted with 1, 2, 3, or 4 substituents independently selected from alkyl, halo, nitro, cyano, aryl, and heteroaryl groups, K3 is either absent or is an arylene or heteroarylene, and such arylene and heteroarylene are each C 1~6 It may be a repeating unit (optionally substituted by 1, 2, 3, or 4 substituents independently selected from alkyl, halo, nitro, cyano, aryl, and heteroaryl groups).

[0037] R 3A , R 3B , R 3C , R 3D, R 3E and R 3F Independently, C 1~6 It may be an aryl molecule optionally substituted with 1, 2, 3, 4, or 5 substituents independently selected from alkyl and halo. 3A , R 3B , R 3C , R 3D , R 3E and R 3F Independently, C 1~6 It may be a phenyl molecule optionally substituted with 1, 2, 3, 4, or 5 substituents independently selected from alkyl and halo.

[0038] B1 may be an arylene optionally substituted with 1, 2, 3, or 4 substituents independently selected from halo, nitro, cyano, aryl, and heteroaryl groups.

[0039] B2 may be absent. Alternatively, B2 may be an arylene optionally substituted with 1, 2, 3, or 4 substituents independently selected from halo, nitro, cyano, aryl, and heteroaryl groups.

[0040] R 4A , R 4B , R 4C , R 4D These can be H or halo independently. Typically, R 4A , R 4B , R 4C , R 4D Each of these is H.

[0041] K1 may be arylene or heteroarylene, and each is C 1~6 It is optionally substituted with 1, 2, 3, or 4 substituents independently selected from alkyl, halo, aryl, and heteroaryl groups. K1 may be an arylene or a heteroarylene, each being C 1~6 It is optionally substituted with 1, 2, 3, or 4 substituents independently selected from alkyl and halo. K1 is substituted with 1, 2, 3, or 4 C 1~6They may be arylenes or heteroarylenes, each optionally substituted with an alkyl group. K1 may be a heteroarylene. K1 is C 1~6 The arylene may be optionally substituted with 1, 2, 3, or 4 substituents independently selected from alkyl and halo. K1 is 1, 2, 3, or 4 C 1~6 It may be an arylene optionally substituted with an alkyl group. K1 may be an arylene. K1 may be naphthalene, phenylene, or C 1~6 It may be alkyl-substituted phenylene. K1 is phenylene, or C 1~6 It may be alkyl-substituted phenylene.

[0042] K2 may not be present. Alternatively, K2 may be an arylene or a heteroarylene, and such arylene and heteroarylene are C 1~6 It is optionally substituted with 1, 2, 3, or 4 substituents independently selected from alkyl and halo. K2 may be an arylene or a heteroarylene, and the arylene and heteroarylene each have 1, 2, 3, or 4 C substituents. 1~6 It is optionally substituted with an alkyl group. K2 may be absent or may be an arylene or heteroarylene. K2 may be an arylene, and the arylene is C 1~6 It is optionally substituted with 1, 2, 3, or 4 substituents independently selected from alkyl and halo. K2 may be an arylene, which has 1, 2, 3, or 4 C substituents. 1~6 It is optionally substituted with an alkyl group. K2 may be arylene. K2 may be phenylene.

[0043] K3 may not be present. Alternatively, K3 may be an arylene or a heteroarylene, and the arylene and heteroarylene are each C 1~6It is optionally substituted with 1, 2, 3, or 4 substituents independently selected from alkyl and halo. K3 may be an arylene or a heteroarylene, and the arylene and heteroarylene each have 1, 2, 3, or 4 C substituents. 1~6 It is optionally substituted with an alkyl group. K3 may be an arylene or a heteroarylene. K3 may be an arylene, and the arylene is C 1~6 It is optionally substituted with 1, 2, 3, or 4 substituents independently selected from alkyl and halo. K3 may be an arylene, which has 1, 2, 3, or 4 C substituents. 1~6 It is optionally substituted with an alkyl group. K3 may be arylene. K3 may be phenylene.

[0044] Formula (II) is preferably formula (II-B):

[0045] [ka] (-K3-K2-K1- is,

[0046] [ka]

[0047] [ka] It can be a repeating unit of (which is).

[0048] The sulfonated hydrocarbon ionomer preferably contains a first repeating unit of formula (I) as defined above and a second repeating unit of formula (II) as defined above, and the molar ratio of the first repeating unit to the second repeating unit is in the range of about 1:99 to about 99:1. The sulfonated hydrocarbon ionomer may be a block copolymer comprising a first block having the repeating unit of formula (I) as defined above and a second block having the second repeating unit of formula (II) as defined above. The number of repeating units of formula (I) in the first block may be in the range of about 3 to about 100 (including both ends), and the number of repeating units of formula (II) in the second block may be in the range of about 3 to about 100 (including both ends).

[0049] Sulfonated hydrocarbon ionomers can be linear. Sulfonated hydrocarbon ionomers can be branched.

[0050] The sulfonated hydrocarbon ionomer may further comprise a polyvalent linker M1 directly bonded via covalent bonds to at least three repeating units. M1 may be a trivalent, tetravalent, pentavalent, or hexavalent linker. Preferably, M1 is selected from a carbon atom, a heteroatom (e.g., N, P, or B), a polyvalent aryl, a polyvalent heteroaryl, a polyvalent aralkyl, or a polyvalent heteroaralkyl, where each of the carbon atom, heteroatom (e.g., P), polyvalent aryl, polyvalent heteroaryl, polyvalent aralkyl, or polyvalent heteroaralkyl is C 1~6 It is optionally substituted with one, two, or three substituents independently selected from alkyl, halo, nitro, cyano, aryl, and heteroaryl groups. Preferably, M1 may be selected from trivalent nitrogen, tetravalent carbon, trivalent phenyl, trivalent pyridyl, trivalent pyrazyl, tetravalent phenyl, tetravalent pyridyl, tetravalent pyrazyl, pentavalent phenyl, pentavalent pyridyl, and hexavalent phenyl, where trivalent phenyl and trivalent pyridyl are each C 1~6 Optionally substituted with one, two, or three substituents independently selected from alkyl, halo, nitro, cyano, aryl, and heteroaryl groups, tetravalent phenyl, tetravalent pyridyl, and trivalent pyradyl are each C 1~6Optionally substituted with one or two substituents independently selected from alkyl, halo, nitro, cyano, aryl, and heteroaryl, pentavalent phenyl is C 1~6 It is optionally substituted with substituents selected from alkyl, halo, nitro, cyano, aryl, and heteroaryl groups. The polyvalent linker M1 is:

[0051] [ka]

[0052] It can be selected from the following. Preferably, the polyvalent linker M1 is

[0053] [ka] That is the case.

[0054] The sulfonated hydrocarbon ionomer provided in step a) preferably contains at least about 0.9 g / cm³ 3 It may have a density of about 2 g / cm³ in dry powder form. The sulfonated hydrocarbon ionomer preferably has a density of about 2 g / cm³ in dry powder form. 3 The following is preferable: approximately 1.5 g / cm³ 3 It may have the following densities.

[0055] The sulfonated hydrocarbon ionomer provided in step a) may have any preferred molecular weight. However, the process of the present invention has the special advantage of providing a means to utilize ion-conducting membranes formed from high molecular weight sulfonated hydrocarbon ionomers that are not readily cast from conventional casting solvents. High molecular weight ionomers may be desirable for improved mechanical properties. High molecular weight ionomers are generally ionomers having a molecular weight greater than about 25,000 daltons. Therefore, it may be preferable that the ionomer provided in step a) has a molecular weight greater than about 25,000 daltons. Molecular weight is the weight-average molecular weight measured using gel permeation chromatography.

[0056] The process may further include a step of adding a reinforcing layer which may contain a porous polymer material, and the sulfonated hydrocarbon ionomer is impregnated into the porous polymer material. Thus, the process provides a reinforced ion-conducting film. The reinforcing layer is typically planar. The porous polymer material may be a fluoropolymer. For example, the porous polymer material may be selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyethersulfone (PES), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), polyimide (PI), polyetherimide (PEI), poly(aryletherketone) (PAEK), poly(arylethersulfone), poly(phenylene sulfide) (PPS), and polyvinylpyrrolidone (PVP). The porous polymer material may be stretched polytetrafluoroethylene (ePTFE). The porous polymer material may contain a polymer backbone based on nitrogen-containing heterocycles. The nitrogen-containing heterocycle may contain a basic functional group. The nitrogen-containing basic functional group may be nitrogen having a lone pair of electrons. Preferably, the polymer skeleton can be selected from polybenzimidazole, poly(pyridine), poly(pyrimidine), polybenzothiazole, polyoxadiazole, polyquinoline, polyquinoxaline, polythiadiazole, polytriazole, polyoxazole, polybenzoxazole, polythiazole, polypyrazole, and their derivatives. Preferably, the polymer skeleton is derived from functionalized polyazoles or zwitterionic polyazoles, such as polybenzimidazole, polytriazole, polythiazole, and polydithiazole, and their derivatives, most preferably polybenzimidazole. It will be understood by those skilled in the art that the polymer skeleton may contain more than one type of nitrogen-containing heterocycle, or a mixture of nitrogen-containing heterocycles and other aliphatic or aromatic groups.

[0057] Preferably, the reinforcing layer has a maximum thickness of 100% of the thickness of the reinforcing ion-conducting film, for example, a maximum thickness of 90%, 80%, 70%, 60%, or 50% of the thickness of the reinforcing ion-conducting film. Preferably, the porous polymer material has a minimum thickness of 5% of the thickness of the ion-conducting film, for example, a minimum thickness of 10%, 15%, 20%, 25%, or 30% of the thickness of the ion-conducting film. Preferably, the porous polymer material of the ion-conducting film may have a thickness in the range of 5 to 95% of the thickness of the reinforcing ion-conducting film, for example, a thickness in the range of 10 to 90%, or 20 to 80% of the thickness of the reinforcing ion-conducting film.

[0058] More than one, for example, two reinforcing layers, each having a sulfonated hydrocarbon ionomer impregnated in at least its region, may be added during the process. If the reinforced ion-conducting film has more than one reinforcing layer, it will be understood that the maximum and / or minimum thickness is the sum of the thicknesses of each porous polymer structure. The thickness of the reinforced ion-conducting film, or each porous polymer structure, as part of the reinforced ion-conducting film can be measured, for example, from scanning electron microscope (SEM) images of a cross-section of the reinforced ion-conducting film when preferably dried at 0% relative humidity.

[0059] The thickness of an ion-conducting membrane prepared by the process depends on its intended application. For example, an ion-conducting membrane for a water electrolyzer is typically thicker than one for a fuel cell, but this is not always the case. Preferably, an ion-conducting membrane has a thickness of at least about 5 micrometers, as measured by analysis of scanning electron microscope (SEM) images of the membrane's cross-section when preferably dried at 0% relative humidity. Preferably, an ion-conducting membrane has a thickness of at least about 6 micrometers, about 7 micrometers, about 8 micrometers, about 9 micrometers, or at least about 10 micrometers. Typically, the thickness of an ion-conducting membrane is about 200 micrometers or less, for example, about 150 micrometers or less, about 100 micrometers or less, about 50 micrometers or less, about 30 micrometers or less, about 25 micrometers or less, or about 20 micrometers or less, when preferably dried at 0% relative humidity. The thickness of an ion-conducting membrane can be measured by analyzing scanning electron microscope (SEM) images of the membrane's cross-section. Preferably, the ion-conducting film, when preferably dried at 0% relative humidity, has a thickness in the range of about 5 to about 200 micrometers, about 6 to about 100 micrometers, about 6 to about 50 micrometers, about 7 to about 30 micrometers, or about 8 to about 20 micrometers (including both ends).

[0060] Step b) comprises casting an ion-conductive film from a mixture of the sulfonated hydrocarbon ionomer provided in step a) and a solvent. Preferably, the solvent includes an alcohol. The alcohol may be linear or branched, typically linear. The solvent may include a mixture of two or more solvents, preferably a mixture of two solvents, for example, a mixture of two different alcohols. One of the solvents may be water. For example, a mixture of alcohol and water may be used. This is because I1 may be high enough in the ionomer provided in step a) to be processable using such a mixture. In this method, the sulfonated hydrocarbon ionomer is first mixed with the solvent. The mixture may be in the form of a dispersion, for example, a fine suspension of ionomer particles, a solution, or may contain dissolved and dispersed components, i.e., partial dissolution of the ionomer in the solvent. The mixture typically contains at least about 1 weight percent of the sulfonated hydrocarbon ionomer relative to the total weight of the mixture. The mixture typically contains a sulfonated hydrocarbon ionomer in a weight of about 30 percent or less of the total weight of the mixture. Any suitable casting method may be used, such as spraying, electro-atomizing, screen printing, rotary screen printing, inkjet printing, brush coating, painting, dipping, bar coating, pad coating, gravure; gap coating techniques such as knife or doctor blade overroll (where the coating is applied to the substrate and then passes through a crack between the knife and support roller); slot die (slot, extrusion) coating (where the coating is squeezed onto the substrate through a slot by gravity or under pressure); metering rod application, such as Meyer bar and gravure coating. Preferably, the casting method is selected from gravure, slot die coating and inkjet printing. Following casting, a drying step is typically carried out to form an ion-conductive film at a temperature in the range of about 50°C to about 150°C. Drying may be carried out in a time of, for example, less than about 15 minutes, typically less than about 10 minutes.

[0061] Furthermore, a process is provided for preparing a catalyst coating film for a fuel cell or water electrolysis device, wherein the catalyst coating film comprises a catalyst layer on the surface of an ion-conducting film. The ion-conducting film is prepared by a method defined herein. The catalyst layer(s) is prepared by forming an ink containing the necessary components of the catalyst layer in a mixture with a solvent. The catalyst layer(s) is cast by any preferred technique, including those described above in relation to the casting of the ion-conducting film. The process of this disclosure is particularly suitable for so-called addition-layer processes for preparing a catalyst coating film, in which the catalyst coating film is constructed layer by layer. The process of this disclosure is also particularly suitable for direct film printing of the catalyst layer, i.e., a process in which the catalyst layer is directly cast onto an ion-conducting film. This is because, for example, if the catalyst layer is cast onto an ion-conducting film, it may be soluble in the solvent used for the catalyst layer ink. However, if a film is cast using an ionomer having an ion exchange capacity I1, and then its ion exchange capacity is reduced to I2, the film having an ion exchange capacity I2 may no longer be soluble in the solvent used for the catalyst layer ink.

[0062] The catalyst layer comprises one or more electrode catalysts. Each of the one or more electrode catalysts is independently a finely pulverized unsupported metal powder or a supported catalyst, and small nanoparticles can be dispersed on a conductive fine-particle carbon support. The electrode catalyst metal is preferably, (i) Platinum group metals (platinum, palladium, rhodium, ruthenium, iridium, and osmium), (ii) Gold or silver, (iii) base metals; Alternatively, an alloy or mixture containing one or more of these metals or their oxides may be selected.

[0063] A suitable and preferred electrode catalyst metal is platinum, which can be alloyed with other noble or base metals. Base metals are tin or transition metals that are not noble metals. Noble metals include platinum group metals (platinum, palladium, rhodium, ruthenium, iridium, or osmium), gold, or silver. Suitable base metals include copper, cobalt, nickel, zinc, iron, titanium, molybdenum, vanadium, manganese, niobium, tantalum, chromium, and tin. More suitable base metals are nickel, copper, cobalt, and chromium. Even more suitable base metals are nickel, cobalt, and copper. When the electrode catalyst is a supported catalyst, the amount of metal particles packed onto the carbon support material is preferably in the range of 10–90% by weight, typically 15–75% by weight, of the weight of the resulting electrode catalyst. The exact electrode catalyst used will depend on the reaction intended to be catalyzed, and its selection is within the capabilities of those skilled in the art.

[0064] The catalyst layer typically contains an ionomer, which may be a perfluorosulfonic acid ionomer. Alternatively, the ionomer may be a sulfonated hydrocarbon ionomer as defined herein. The catalyst layer may further contain additional components. Such additional components include, but are not limited to, catalysts that facilitate oxygen evolution and are therefore beneficial in cell inversion conditions and high potential shifts, or hydrogen peroxide decomposition catalysts. Examples of such catalysts and any other additives suitable for inclusion in the catalyst layer are known to those skilled in the art.

[0065] The present invention also provides a process for preparing a membrane electrode assembly comprising a catalyst-coated ion-conducting membrane and a gas diffusion layer or porous transport layer present on at least one of the catalyst layers. The anode and cathode gas diffusion layers are preferably based on conventional gas diffusion substrates. Typical substrates include nonwoven paper or webs containing a network of carbon fibers and a thermosetting resin binder (e.g., TGP-H series carbon fiber paper available from Toray Industries Inc. (Japan), or H2315 series available from Freudenberg FCCT KG (Germany), or Sigracet® series available from SGL Technologies GmbH (Germany), or AvCarb® series from Ballard Power Systems Inc.), or carbon fiber cloth. The carbon paper, web, or cloth can be further processed and incorporated into the MEA to enhance either wettability (hydrophilicity) or moisture resistance (hydrophobicity). The nature of any processing depends on the type of fuel cell and the operating conditions used. The substrate's wettability can be enhanced by incorporating materials such as amorphous carbon black through impregnation from a liquid suspension, or by impregnating the substrate's pore structure with a colloidal suspension of a polymer such as PTFE or polyfluoroethylene propylene (FEP), followed by drying and heating above the polymer's melting point to increase its hydrophobicity. In applications such as PEMFCs, a microporous layer can be applied to the gas diffusion substrate on the surface that will come into contact with the catalyst layer. The microporous layer typically contains a mixture of carbon black and a polymer such as polytetrafluoroethylene (PTFE). The porous transport layer is preferably based on a conventional porous transport substrate such as titanium mesh. [Examples]

[0066] Synthesis of ionomer mixtures In a mixture of isopropyl alcohol (IPA) and water, a sulfonated phenylated polyphenylene ionomer having repeating units of formula IB and hydrophobic repeating units (ion exchange capacity (IEC) in the range of 2.8 to 3.1 meq / g and approximately 1.2 g / cm³) 3 The following mixtures (having the density of ) were prepared.

[0067] [Table 1]

[0068] Mass and dimensional change test The product contains a sulfonated phenylated polyphenylene ionomer having repeating units of formula IB and hydrophobic repeating units, and is compliant with IEC standards in the range of 2.8 to 3.1 meq / g and 1.2 g / cm³. 3 An ion-conducting film having a density was subjected to heat treatment in a hot oven. Two films were placed at 140°C, one for 5 minutes (Example 1) and the other for 10 minutes (Example 2). Two films were placed at 180°C, one for 5 minutes (Example 3) and the other for 10 minutes (Example 4). A total of five films were obtained, excluding the standard blank.

[0069] Next, the heat-treated films are subjected to a swelling test. The dimensions and mass of the films are measured (under ambient conditions), and then the films are returned to their original state by immersing them in 80°C water for 24 hours (wet conditions). During this time, the films swell. After 24 hours, they are removed, and then their mass and dimensions are measured again.

[0070] Figure 2 shows the mass change rates for the blank and Examples 1-4. This reduction in mass change, particularly after treatment at 180°C, provides a film with more favorable water incorporation, which may be due to a decrease in IEC. An ideal film (from a mechanical standpoint) should exhibit the lowest water incorporation and the smallest dimensional change (resistance to deformation). There is a clear tendency for water incorporation to decrease with higher temperatures and longer heat treatments (comparing the dry state to the wet state), and for water incorporation to increase with less heat treatment (see accompanying documentation).

[0071] In Figure 4, a similar trend is observed for the rate of change of the in-plane (x) dimension.

[0072] It contains a sulfonated phenylated polyphenylene ionomer having repeating units of formula IB and hydrophobic repeating units, and has an IEC rating in the range of 3.1 to 3.4 meq / g and approximately 1.2 g / cm³. 3 Further experiments were also conducted on ion-conducting films with a density of . In these experiments, the films were heat-treated in a hot oven as shown in Table 2.

[0073] [Table 2]

[0074] Figure 3 shows the mass changes of Examples 5-10 under the same swelling test conditions. The decrease in mass change is observed again, especially after treatment above 160°C, providing a film with more advantageous water uptake, which may be due to a decrease in IEC.

[0075] In Figure 5, a similar trend can be observed for the rate of change of the in-plane (x) dimension.

[0076] Figure 6 correlates the data shown in Figures 3 and 5 with respect to the rate of change in mass and the rate of change in in-plane (x) dimension, demonstrating the advantageous properties, particularly after heat treatment at temperatures above 180°C.

[0077] Measurement of ion exchange capacity The IEC of the membrane was measured using conventional titration techniques. Acid form (H + The membrane was immersed in a 1.0 M NaCl solution for 24 hours and then H + Ions Na + It is converted to the sodium salt form by exchange with ions. Then, the exchanged H in the solution + The ions can be titrated with a 0.02N NaOH solution. The theoretical ion exchange capacity, calculated from the degree of sulfonation, is obtained from the formula: Ion exchange capacity (meq / g) = Ionic mmol concentration / Mass of the dried film at 25°C.

[0078] Figure 7 shows the IEC values ​​for Examples 5-10, clearly demonstrating the IEC loss due to the loss of sulfonate groups, which increases with increasing heat treatment temperature.

[0079] Figure 8 shows the correlation between the IEC after heat treatment and the percentage change in mass from the dry film to the wet film, measured using the procedure described above. The beneficial decrease in the change from dry mass to wet mass after heat treatment correlates with the loss of IEC.

[0080] thermogravimetric analysis Thermogravimetric analysis was performed on samples 1-5. The samples were placed in a TGA / DSC pan and positioned in an SDT 650 DSC / TGA system. After holding the samples at 30°C for 20 minutes, the temperature was increased to 600°C at a rate of 10°C / min. Heat flow and mass changes were measured as functions of temperature.

[0081] The results are shown in Figures 9 and 10. From these figures, a first mass loss can be observed between 80 and 100°C. This may be related to water loss. A second mass loss occurs between 150 and 250°C. This is related to sulfonate loss, as seen in the reference: "Highly Stable, Low Gas Crossover, Proton-Conducting Phenylated Polyphenylenes", Angew. Chem. Int. Ed., 56, 2017 pp 9058-9061. As shown in Figure 5, increasing the amount of alcohol solvent relative to water does not significantly change the thermal transition.

[0082] FTIR measurement FTIR data were obtained from Examples 5–10 using an ATR FTIR instrument. Spectra were collected at room temperature using a crystalline diamond plate. The plate was left blank for the background spectrum, and the collected film spectra were then corrected by subtracting the background spectrum.

[0083] The spectrum is shown in Figure 1. This data shows the change in chemical structure during heat treatment above 180°C. Specifically, from 1000 to 1050 cm⁻¹. -1 The disappearance of the peaks in the vicinity is associated with the disappearance of sulfonic acid, and the peak area is clearly reduced (100℃=140℃=160℃>180℃>>200℃>>220℃).

Claims

1. Ion exchange capacity I ２ A process for preparing an ion-conducting film containing a sulfonated hydrocarbon ionomer having a meq / g concentration, comprising the following steps: a) Ion exchange capacity I １ A step of providing a sulfonated hydrocarbon ionomer having meq / g, b) A step of casting an ion-conducting film from a mixture of the sulfonated hydrocarbon ionomer provided in step a) and a solvent, c) The ion-conducting membrane prepared in step b) has an ion exchange capacity of I １ Ion exchange capacity from meq / g ２ Process to reduce to meq / g (I ２ is I １ A process that includes the application of the step (which is less than).

2. The process according to claim 1, wherein the treatment applied in step c) is heat treatment.

3. I １ The process according to claim 1 or 2, wherein the concentration is approximately 5 meq / g or more.

4. I ２ The process according to any one of claims 1 to 3, wherein the amount is approximately 4 meq / g or less.

5. The process according to any one of claims 1 to 4, wherein the sulfonated hydrocarbon ionomer provided in step a) has a molecular weight greater than approximately 25,000 daltons.

6. The process according to any one of claims 1 to 5, wherein the solvent used in step b) includes an alcohol.

7. The process according to any one of claims 1 to 6, wherein the sulfonated hydrocarbon ionomer is selected from poly(arylene ether), poly(arylene ether ketone), poly(arylene sulfone), poly(imide), poly(benzimidazole), polyphenylene, and sulfonated derivatives of phenylated polyphenylene.

8. The process according to any one of claims 1 to 7, further comprising the step of adding a reinforcing layer.

9. A process for preparing a catalyst coating film for a fuel cell or water electrolysis device, wherein the catalyst coating film includes a catalyst layer on the surface of an ion-conducting film, and the process is: i) Preparing an ion-conducting film by the process described in any one of claims 1 to 8, ii) preparing a catalyst layer, A process comprising: preparing the catalyst layer and applying the ion-conducting film to the catalyst layer; or preparing the ion-conducting film and applying the catalyst layer to the ion-conducting film.

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