Reinforced composite polymer electrolyte membrane with improved thermal stability and dimensional stability

Abstract

The invention relates to a reinforced composite polymer electrolyte membrane which ensures mechanical stability, structural stability and thermal stability.

Description

Technical Field

[0001] This invention relates to an enhanced composite polymer electrolyte membrane that ensures mechanical, structural, and thermal stability. Typically, the polymer electrolyte membrane according to this invention can be applied to hydrogen fuel cells or water electrolysis systems, and also to energy devices or components such as redox flow batteries and reverse electrodialysis (RED). Background Technology

[0002] Polymer electrolyte membranes are solid electrolytes in thin film form. They selectively transfer cations (hydrogen ions) and block hydrogen gas. They can be used in water electrolysis systems to produce hydrogen or fuel cell systems that use hydrogen to generate electricity.

[0003] In water electrolysis systems and fuel cell systems, polymeric electrolyte membranes are introduced in the form of membrane electrode assemblies (MEAs) with electrode layers that initiate electrochemical reactions coated on both sides of the electrolyte membrane. In this case, the main function of the polymeric electrolyte membrane or cation exchange membrane is to effectively transfer hydrogen ions generated by the catalytic reaction through the electrode layers.

[0004] In water electrolysis / fuel cell systems, the role of cation-conductive polymer electrolyte membranes is to achieve performance through hydrogen ion transfer, separate reaction / generated gases, and ensure the mechanical strength required of engineering plastics in the system.

[0005] Since hydrogen ion transport capacity is considered to play a fundamental role, in order to minimize resistance in the thickness direction, electrolyte membranes in the form of a single membrane (monolayer thin film) have been prepared using only electrolytes with high ion exchange capacity (IEC). This trend is particularly prominent in the field of water electrolysis systems.

[0006] In the case of fabricating a single membrane or monolayer thin film to improve the hydrogen ion conductivity of the polymer electrolyte membrane, i.e., to maximize the IEC (hydrogen ion conductivity), there is a problem that the hydrogen permeability also increases with the improvement of mass transfer properties. In water electrolysis systems, in particular, the mixing of oxygen and hydrogen poses a possibility of fire or explosion. In fuel cell systems, in addition to safety issues, the mixing of reactant gases can also lead to a decrease in the open circuit voltage of the stack.

[0007] Furthermore, the single-layer thin-film morphology presents mechanical stability issues. Specifically, in the subsequent MEA transfer process, it is exposed to an environment subjected to a certain degree of heat and tension. Thermal expansion can damage the MEA structure, resulting in problems with thermal and tensile stability. Additionally, both fuel cells and water electrolysis systems operate at temperatures above 60°C. Long-term operation or the formation of localized hot spots can lead to thermal deformation, making it difficult to maintain selectivity (hydrogen ion conductivity relative to hydrogen permeability). In severe cases, this can create pinholes, compromising the stability of the system during operation.

[0008] Therefore, ensuring thermal and structural stability at fuel cell / water electrolysis process temperatures or operating temperatures is considered an essential element. Summary of the Invention

[0009] The problem that the invention aims to solve The present invention is proposed to solve the above-mentioned problems, and aims to provide an enhanced composite polymer electrolyte membrane that ensures thermal and structural expansion stability through a composite structure.

[0010] The technical problems of this invention are not limited to those mentioned above. Through the following description, those skilled in the art will be able to clearly understand other technical problems not mentioned.

[0011] means for solving problems According to a preferred embodiment of the present invention, an enhanced composite polymer electrolyte membrane is provided, wherein the polymer electrolyte membrane is formed by coating an ionomer dispersion onto a carrier, characterized in that the ionomer contains sulfonic groups for hydrogen ion conduction, the carrier is a porous substrate with a higher melting point than the ionomer, the polymer electrolyte membrane is configured to include a composite layer formed by impregnating the ionomer inside the carrier, and an electrolyte layer composed of the ionomer in the upper and lower parts of the composite layer, and the gradient of sulfur (S) content (wt%) is determined by energy dispersive spectroscopy (EDS) analysis of the upper electrolyte layer, the composite layer and the lower electrolyte layer along the thickness cross section.

[0012] At this time, the sulfur content (wt%) of the upper electrolyte layer, the composite layer and the lower electrolyte layer can be the average value of the sulfur content calculated by performing an EDS line scan on the part with the thickest vertical thickness in each layer (the longest vertical line connecting the upper and lower ends of each layer) based on a specific cross section of the polymer electrolyte membrane.

[0013] At this time, the sulfur (S) content of the upper electrolyte layer or the lower electrolyte layer can be 1.5 times to 5.0 times that of the sulfur (S) content of the composite layer, preferably 1.5 times to 3.5 times.

[0014] The ionomer may be a fluorinated ionomer or a hydrocarbon ionomer mixed with compounds containing sulfonic acid groups.

[0015] The total dimension change of the polymer electrolyte membrane at 200°C, as determined by thermomechanical analysis (TMA), can be less than 2,000 μm, and preferably less than 1,500 μm.

[0016] The total dimension change of the polymeric electrolyte membrane at 200°C, as determined by thermomechanical analysis (TMA), can be 20% to 60% smaller than that of a single membrane (which, unlike the polymeric electrolyte membrane, is composed solely of the ionomer without the carrier, and has the same membrane thickness and ionomer composition).

[0017] Furthermore, the thermal transition temperature of the polymeric electrolyte membrane, according to thermomechanical analysis (TMA), can be 5% to 20% higher than that of a single membrane (which, unlike the polymeric electrolyte membrane, is composed solely of the ionomer without the carrier, and has the same membrane thickness and ionomer composition).

[0018] Furthermore, on the dimension change curve based on thermomechanical analysis (TMA), the slope of the straight line connecting the point of thermal transition temperature and the point of 200°C can be between 20% and 60% compared to the slope of the same straight line for a single membrane (which, unlike the polymer electrolyte membrane, is composed solely of the ionomer without the carrier, and has the same membrane thickness and ionomer species).

[0019] The hydrogen permeability of the polymer electrolyte membrane can be 2.0 mA / cm. 2 The polymer electrolyte membrane described below can be used in water electrolysis systems or fuel cells.

[0020] According to another preferred embodiment of the present invention, a membrane electrode assembly for a fuel cell or a water electrolysis system comprising the polymeric electrolyte membrane as described above is provided, and a fuel cell or water electrolysis system comprising the aforementioned polymeric electrolyte membrane is provided.

[0021] Invention Effects The enhanced composite polymer electrolyte membrane of the present invention, as described above, has the following effect: by ensuring high thermal-dynamic stability, it can maintain high performance even under the conditions of the preparation process temperature or operating temperature of the water electrolysis / fuel cell system.

[0022] The effects of the present invention are not limited to those mentioned above, but also include other effects that are clearly understood by those skilled in the art through the entire specification but are not explicitly mentioned. Attached Figure Description

[0023] Figure 1 This is a cross-sectional SEM image showing the thickness direction of the reinforced composite polymer electrolyte membrane according to a preferred embodiment of the present invention, analyzed by EDS at the target point.

[0024] Figure 2 This is a cross-section EDS analysis chart of spectra 27-29 according to Embodiment 2 of the present invention.

[0025] Figure 3 These are the TMA curves (scale change graphs by temperature) of samples 1 to 3 according to embodiments of the present invention.

[0026] Figure 4 This is a cross-sectional schematic diagram of the enhanced composite polymer electrolyte membrane of the present invention. Detailed Implementation

[0027] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The advantages, features, and methods of achieving the present invention will become apparent from the accompanying drawings and the detailed embodiments described below. However, the present invention is not limited to the embodiments disclosed below and can be implemented in different ways. These embodiments are provided merely to complete the disclosure of the present invention and to fully inform those skilled in the art of the scope of the invention, which is defined only by the scope of the claims. Throughout this specification, the same reference numerals refer to the same components.

[0028] Unless otherwise defined, all terms used in this specification (including technical and scientific terms) are to be used in the sense commonly understood by one of ordinary skill in the art to which this invention pertains. Furthermore, terms already defined in commonly used dictionaries should not be idealized or over-interpreted unless explicitly and specifically defined. The terminology used in this specification is for illustrative purposes only and is not intended to limit the invention. In this specification, the singular form also includes the plural form unless specifically mentioned in the context.

[0029] The use of “comprises” and / or “comprising” in this specification does not exclude the presence or addition of more than one other component, step, action and / or element besides those mentioned.

[0030] First, the present invention provides an enhanced composite polymer electrolyte membrane, wherein the polymer electrolyte membrane is formed by coating an ionomer dispersion onto a carrier. The ionomer is characterized by containing sulfonic groups for hydrogen ion conduction, and the carrier is a porous substrate with a higher melting point than the ionomer. The polymer electrolyte membrane is configured to include a composite layer formed by impregnating the ionomer within the carrier, and an electrolyte layer composed of the ionomer in the upper and lower portions of the composite layer. Furthermore, when energy dispersive spectroscopy (EDS) analysis is performed on the upper electrolyte layer, the composite layer, and the lower electrolyte layer along the thickness cross section, the gradient of sulfur (S) elemental content (wt%) is determined.

[0031] At this point, the sulfur content (wt%) of the upper / lower electrolyte layer and composite layer can be defined and calculated using various methods applicable to EDS analysis. Specifically, EDS analysis can measure and calculate the elemental content at a specific point, line, or area.

[0032] In the following embodiments, the present invention experimentally determined the values ​​calculated by EDS analysis of specific points of each layer. However, as another embodiment, the average sulfur content calculated by performing an EDS line scan on the part with the thickest vertical thickness of each layer (the longest vertical line connecting the upper and lower ends of each layer) based on a specific cross section of the polymer electrolyte membrane can be defined as the sulfur content (wt%) value of the upper / lower electrolyte layer composite layer.

[0033] Specifically, refer to Figure 4 Based on a specific cross section, the sulfur content of the upper electrolyte layer can be defined as the average value of the sulfur content calculated when performing an EDS line scan on the part with the thickest part of the upper electrolyte layer, i.e., the part with the longest vertical line connecting the upper end line y3 of the upper electrolyte layer and the boundary line y2 of the lower composite layer.

[0034] Similarly, the sulfur content of each layer can be calculated using the same method for the thickest part of the composite layer in the y2-y1 vertical direction and the thickest part of the lower electrolyte layer in the y1-y0 vertical direction.

[0035] 1. Electrolyte (ionomer) and composite layer application materials Ionomers that function as electrolytes can be any substance having functional groups capable of transporting hydrogen ions, and preferably may contain sulfonic groups. Specifically, fluorinated ionomers or hydrocarbon ionomers mixed with compounds containing sulfonic groups can be used.

[0036] The melting point of the carrier used in the composite structure should be higher than that of the ionomer. Preferably, all types of porous materials with a melting point more than 1.2 times higher can be used, and materials with a melting point of 300°C or higher are generally applicable.

[0037] As the carrier material constituting the composite layer, polytetrafluoroethylene (PTFE, melting point about 327°C) or e-PTFE, cerium oxide (ceria, melting point about 2,400°C), polyimide (melting point about 247~388°C), etc. can be used.

[0038] The carrier is a porous material, and it is suitable to use a material with a porosity of at least 70%, preferably 80% or more.

[0039] 2. Composite layer Whether a reinforced composite electrolyte membrane with an internal composite layer has been formed can be confirmed by SEM cross-section analysis. Energy dispersive spectroscopy (EDS) analysis of the upper electrolyte layer, composite layer and lower electrolyte layer along the thickness direction can be performed to confirm the presence of functional group elements (sulfur, S) in the ionomer based on the thickness direction distribution differences.

[0040] Compared to the pure ionomer layers (electrolyte layers) at the top and bottom of the composite layer, the sulfur (S) content of the sulfonic acid groups in the composite layer region is low. In order to effectively realize the effect of enhanced composite in the electrolyte membrane properties, the sulfur content of the electrolyte layer needs to be more than 1.5 times that of the composite layer region, and more effectively, it needs to be more than 2.0 times.

[0041] The sulfur content of the electrolyte layer relative to the composite layer is determined by the following variables: the porosity of the carrier, the degree of porosity reduction due to thickness shrinkage during the composite process of coating with ionomer, the filling rate of the electrolyte (ionomer) relative to the carrier pores, and the volume ratio of the electrolyte layer to the composite layer. These variables are the factors that determine the thermal stability, mechanical stability and dimensional stability of the polymer electrolyte membrane.

[0042] For example, the higher sulfur content in the electrolyte layer compared to the composite layer can be attributed to the combined effects of the following factors: the composite layer contains a higher content of a carrier with relatively high thermal stability; during the electrolyte coating process, high-intensity shrinkage occurs along the thickness direction, resulting in a significant reduction in the porosity of the carrier; and the electrolyte filling rate within the carrier pores is relatively low, leaving residual pores. Consequently, during the water absorption process of the electrolyte membrane, water preferentially fills these residual pores, reducing the swelling of the membrane itself or changes in its external dimensions caused by water absorption.

[0043] Therefore, the sulfur content of the electrolyte layer relative to the composite layer can be increased, but if it exceeds 5 times, preferably more than 3.5 times, it means that the sulfonic acid equivalent of the composite layer is significantly reduced. This means that the equivalent weight is beyond the range of use as an electrolyte, which leads to an excessive decrease in the hydrogen ion transport capacity of the composite layer. Consequently, the hydrogen ion transport capacity in the thickness direction, i.e., the effective conductivity, decreases relative to the hydrogen ion transport capacity of the total volume of the electrolyte membrane.

[0044] 3. Thermal stability and dimensional stability The thermal-dynamic stability of a material can be confirmed using thermomechanical analysis (TMA). After fixing the electrolyte membrane in a TMA apparatus, heating it to 200°C, the temperature at which the functional group of the electrolyte, sulfonicacid, decomposes, allows for the confirmation of the final thermal expansion dimensions at the temperature at which the material's mobility begins to manifest, i.e., the thermal transition temperature.

[0045] A comparative experiment was conducted on a single membrane formed solely from pure electrolyte and the reinforced composite polymer electrolyte membrane according to the present invention, prepared using the same process. It was confirmed that, compared to the single membrane, the thermal transition temperature is 5% to 20% higher (specifically above 5°C, preferably above 10°C), and the thermal expansion dimension is 20% to 60% smaller (specifically below 2,000 μm, preferably below 1,500 μm), thereby confirming a significant improvement in thermal stability and dimensional stability.

[0046] Example 1: Preparation of reinforced composite polymer electrolyte membrane (sample 1) The electrolyte (ionomer) used was 3M's middle side chain PFSA (perfluorosulfonic acid), with an equivalent weight of 720. The ionomer dispersion had a solids content of 20 wt%, and the solvent was added to water and 1-propanol in a 1:1 ratio and prepared using a rotary mixer.

[0047] The carrier is e-PTFE (Expanded Polytetrafluoroethylene) with a porosity of 85%. The e-PTFE is filled with the above-mentioned electrolyte and coated on both sides using an applicator, so that the composite layer occupies 50% of the total volume in the thickness direction. In order to remove the solvent in the electrolyte, it is dried at 70°C for 1 hour and then heat-treated (Annealing) at 170°C for 10 minutes to obtain a reinforced composite membrane in thin film form.

[0048] Example 2: EDS Analysis To verify the composite structure of the enhanced composite polymer electrolyte membrane, EDS (Energy Dispersive Spectrometry) analysis was performed using a JEOL JSM-7600F instrument. The elemental amounts of C, S, F, and O were determined at an accelerating voltage of 15 kV, confirming the elemental distribution of the upper electrolyte layer, the inner composite layer, and the lower electrolyte layer. It was confirmed that the S element ratio of the pure electrolyte layer to the composite layer was [value missing], with the electrolyte layer having a S element content 2 to 3 times higher. Figure 1 In the diagram, Spectrum 27 represents the upper electrolyte layer, Spectrum 28 represents the composite layer, and Spectrum 29 represents the lower electrolyte layer.

[0049] [Table 1]

[0050] In Table 1 above, Wt% is the weight percentage, which represents the value of each component of the substance as a weight percentage. Wt%Sigma represents the standard deviation of the weight percentage, and Atomic% represents the percentage of the number of atoms. Figure 2 This is a cross-section EDS analysis chart of spectra 27-29.

[0051] Refer to Table 1 above and Figure 2 This method can clearly identify the gradient of sulfur (S) content (wt%) along the thickness direction between the upper and lower electrolyte layers and the internal composite layer. In particular, the sulfur (S) content is the most significant indicator in terms of ease of measurement, representativeness of the composite structure as a core element constituting ionomer functional groups, and the correlation between the composition of the composite layer and the control of porosity / filling rate.

[0052] Example 3: TMA Analysis To confirm the thermal behavior of the reinforced composite membrane, sample size changes with temperature were measured using a Discovery TMA 450EM instrument from Waters. Samples with a fixed width of 5 mm and a length of 20 mm or more were heated from 25 °C to 200 °C at a rate of 5 °C per minute. Size changes were observed, prioritizing the observation of the thermal transition temperature at which material mobility began. This confirmed the transition delay range of the composite membrane structure relative to the single membrane and the length change at the final temperature (200 °C).

[0053] Three samples were used in the analysis according to the thermomechanical analysis (TMA). Sample 1 was the enhanced composite polymer electrolyte membrane according to Example 1 above.

[0054] Sample 2 was prepared as follows. 3M's middle-side chain PFSA (perfluorosulfonic acid) with an equivalent weight of 720 was used as the electrolyte. The first ionomer dispersion had a solids content of 20 wt%, and the solvent was prepared by mixing water and 1-propanol in a 1:1 ratio using a rotary mixer. For the second ionomer dispersion used in the composite layer, cerium oxide at a content of 8000 ppm relative to the solids content was added to the previously prepared first ionomer dispersion, and further dispersion was carried out using a rotary mixer.

[0055] In the film-forming process, the first ionomer dispersion is first coated using an applicator. After drying at 70°C for 30 minutes to remove the solvent, the second ionomer dispersion is also coated on the upper part of the first coated surface. After drying at 70°C for 30 minutes to form two layers, the first ionomer dispersion is coated again. Finally, the film is dried at 70°C for 1 hour and heat-treated at 170°C for 10 minutes to prepare a three-layer structure.

[0056] Sample 3 served as the control group, and its preparation was as follows. 3M's middle-side-chain PFSA (perfluorosulfonic acid) was used as the electrolyte, with an equivalent weight of 720. The ionomer dispersion had a solids content of 20 wt%, and the solvent was added to water and 1-propanol in a 1:1 ratio using a rotary mixer.

[0057] The prepared ionomer dispersion was coated only once using the same method as that used for samples 1 and 2. The drying and heat treatment were also the same as the final drying conditions for samples 1 and 2: drying at 70°C for 1 hour and heat treatment at 170°C for 10 minutes.

[0058] The EDS analysis results for samples 1 to 3, including the sulfur (S) content ratio of the electrolyte layer to the composite layer, the thermal transition temperature, and the total dimension change at 200℃, are shown in Table 2 below. The dimension change curve based on temperature is also shown in the figure. Figure 3 (Sample 1 is red 0628C-MD, sample 2 is blue 0628D-MD, and sample 3 is black single membrane).

[0059] [Table 2]

[0060] It can be confirmed that, in the case of sample 1, which is equivalent to the reinforced composite polymer electrolyte membrane according to the present invention, and sample 2, which is based on it with the addition of cerium oxide, the flow initiation temperature, i.e., the thermal transition temperature, is about 10°C higher than that of sample 3, which is a single membrane. Subsequently, as the temperature increases, sample 3 undergoes a rapid dimensional change. In contrast, samples 1 and 2 form a gradual delay range, and finally, the dimensional change at 200°C (the temperature at which the sulfonic group begins to decompose and is the upper limit of the temperature for processes such as heat treatment or MEA electrode processes) is reduced to about half the level of sample 3 (reference). Figure 3 ).

[0061] Unlike Sample 3, Samples 1 and 2 exhibit a so-called "delayed range" where the region of formal thermal expansion is postponed to a relatively higher temperature range. This is because, during the film-forming process of the reinforced composite membrane, the electrolyte and the carrier are exposed to the solvent. During the drying-annealing process, the internal structure of the membrane is rearranged. During drying, the forces acting on the interior of the composite layer and the surface of the electrolyte membrane are different, and the forces between the two layers compete with each other, thereby increasing the thermal resistance and physical resistance of the material.

[0062] Furthermore, it was confirmed that although Sample 2 was reinforced by adding cerium oxide, which has a higher melting temperature, its thermal transition temperature was slightly lower than that of Sample 1, and its total dimension change at 200°C was slightly larger. This may be because Sample 1 achieves reinforcement by allowing the electrolyte to permeate into the three-dimensional structure between the nodes and fibrils of the e-PTFE reinforcement material itself, while Sample 2 is prepared by dispersing cerium oxide in an electrolyte dispersion, thus achieving reinforcement through cerium oxide adsorption onto the aggregated electrolyte polymer unit structure. If the metal oxide is prepared into a network structure and impregnated with electrolyte in the same manner, it can exhibit even better reinforcement properties than Sample 1.

[0063] In summary, by achieving enhanced composite structure and forming an appropriate sulfur (S) content gradient in the thickness direction, the composite effect can be maximized while improving thermal-dimensional stability.

[0064] When the composite layer is achieved by forming an appropriate level of sulfur content gradient, the polymer electrolyte membrane can be prepared in such a way that the total dimension change at 200°C is less than 2,000 μm, preferably less than 1,500 μm, according to thermomechanical analysis (TMA). This is 20% to 60% smaller than the total dimension change of a single membrane.

[0065] Furthermore, the temperature at which fluidity begins to develop, i.e. the thermal transition temperature, is 5% to 20% higher than that of a single film. Therefore, the starting point of thermal expansion is also delayed to a relatively high temperature range, thus achieving thermal-dimensional stability across the entire range from the operating / preparation temperature to the upper limit temperature (200°C).

[0066] In particular, the small thermal expansion dimension at 200°C is a result of the aforementioned delay range. This physical characteristic is a property of reinforced composite polymer electrolyte membranes with a sulfur content gradient along the thickness direction. On the dimension change curve according to TMA analysis, the slope of the straight line connecting the point of thermal transition temperature and the point of 200°C is smaller than that in a single membrane, preferably at a level of 20% to 60%.

[0067] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, those skilled in the art will understand that the present invention can be implemented in other specific ways without changing the technical concept or essential features of the invention. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

Claims

1. A reinforced composite polymer electrolyte membrane, wherein the polymer electrolyte membrane is formed by coating a carrier with an ionomer dispersion, characterized in that, The ionomer contains sulfonic groups for hydrogen ion conduction. The carrier is a porous substrate with a higher melting point than the ionomer. The polymer electrolyte membrane is configured to include a composite layer formed by impregnating the ionomer inside the carrier, and an electrolyte layer composed of the ionomer in the upper and lower parts of the composite layer. The gradient of sulfur (S) content (wt%) is determined when the upper electrolyte layer, the composite layer and the lower electrolyte layer are analyzed by energy dispersive spectroscopy (EDS) along the thickness cross section.

2. The reinforced composite polymer electrolyte membrane according to claim 1, characterized in that, The sulfur content (wt%) of the upper electrolyte layer, the composite layer, and the lower electrolyte layer is the average value of the sulfur content calculated by performing an EDS line scan on the thickest part of each layer in the vertical direction, based on a specific cross-section of the polymer electrolyte membrane. The thickest part is the part with the longest vertical line connecting the upper and lower ends of each layer.

3. The enhanced composite polymer electrolyte membrane according to claim 1, characterized in that, The sulfur (S) content of the upper electrolyte layer or the lower electrolyte layer is 1.5 to 5.0 times that of the composite layer.

4. The enhanced composite polymer electrolyte membrane according to claim 1, characterized in that, The sulfur (S) content of the upper electrolyte layer or the lower electrolyte layer is 1.5 to 3.5 times that of the composite layer.

5. The enhanced composite polymer electrolyte membrane according to claim 1, characterized in that, The ionomer is a fluorine-based ionomer or a hydrocarbon-based ionomer mixed with compounds containing sulfonic acid groups.

6. The enhanced composite polymer electrolyte membrane according to claim 1, characterized in that, The total dimension change of the polymer electrolyte membrane at 200°C, as determined by thermomechanical analysis (TMA), is less than 2,000 μm.

7. The enhanced composite polymer electrolyte membrane according to claim 1, characterized in that, The total dimension change of the polymer electrolyte membrane at 200°C, as determined by thermomechanical analysis (TMA), is less than 1,500 μm.

8. The reinforced composite polymer electrolyte membrane according to claim 1, characterized in that, The total dimension change of the polymer electrolyte membrane at 200°C, as determined by thermomechanical analysis (TMA), is 20% to 60% smaller than that of a single membrane. The single membrane differs from the polymer electrolyte membrane in that it does not have the carrier but is composed solely of the ionomer, and its membrane thickness and the type of ionomer are the same.

9. The reinforced composite polymer electrolyte membrane according to claim 1, characterized in that, The thermal transition temperature of the polymer electrolyte membrane, as determined by thermomechanical analysis (TMA), is 5% to 20% higher than that of the single membrane. The single membrane differs from the polymer electrolyte membrane in that it does not have the carrier but is composed solely of the ionomer, and its membrane thickness and the type of ionomer are the same.

10. The reinforced composite polymer electrolyte membrane according to claim 1, characterized in that, On the dimension change curve of the polymeric electrolyte membrane according to thermomechanical analysis (TMA), the slope of the straight line connecting the point of thermal transition temperature and the point of 200°C is 20% to 60% higher than the slope of the same straight line of a single membrane, which differs from the polymeric electrolyte membrane in that it does not have the carrier but is composed only of the ionomer, and has the same membrane thickness and ionomer composition.

11. The reinforced composite polymer electrolyte membrane according to claim 1, characterized in that, The hydrogen permeability of the polymer electrolyte membrane is 2.0 mA / cm². 2 the following.

12. The reinforced composite polymer electrolyte membrane according to claim 1, characterized in that, The polymer electrolyte membrane is a PEM used in water electrolysis systems or a PEM used in fuel cells.

13. A membrane electrode assembly for a fuel cell, characterized in that, The membrane electrode assembly for fuel cells comprises the enhanced composite polymer electrolyte membrane according to any one of claims 1 to 12.

14. A membrane electrode assembly for a water electrolysis system, characterized in that, The membrane electrode assembly for the water electrolysis system comprises the enhanced composite polymer electrolyte membrane according to any one of claims 1 to 12.

15. A fuel cell, characterized in that, The fuel cell comprises the enhanced composite polymer electrolyte membrane according to any one of claims 1 to 12.

16. A water electrolysis system, characterized in that, The water electrolysis system comprises the enhanced composite polymer electrolyte membrane according to any one of claims 1 to 12.

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