Polymer electrolyte membrane, membrane electrode assembly and redox flow battery

Abstract

A composite electrolyte membrane for an electrochemical device is provided, comprising at least one reinforced polymer electrolyte membrane having a first surface and an opposite second surface. The reinforced polymer electrolyte membrane comprises a microporous polymer structure and an ion exchange material, the ion exchange material being at least partially embedded within the microporous polymer structure to render the microporous polymer structure occlusive. The composite electrolyte membrane further comprises a plurality of porous layers, including a first porous layer and a second porous layer, the first porous layer being adjacent to a first surface of the first reinforced polymer electrolyte, and the second porous layer being adjacent to a second surface of the reinforced polymer electrolyte. Also disclosed are membrane electrode assemblies comprising such composite electrolyte membranes, and redox flow batteries, fuel cells and electrolysis devices comprising such membrane electrode assemblies.

Description

[Technical field]

[0001] The present invention relates to a composite electrolyte membrane for electrochemical devices such as redox flow batteries. The composite electrolyte membrane comprises a reinforced polymer electrolyte membrane and a plurality of porous layers, including a first porous layer and a second porous layer, the first porous layer and the second porous layer being adjacent to opposite surfaces of the reinforced polymer electrolyte membrane. Also disclosed are membrane electrode assemblies comprising such composite electrolyte membranes, as well as fuel cells, electrolyzers and redox flow batteries comprising such membrane electrode assemblies. Such composite electrolyte membranes exhibit high puncture resistance. As a result, redox flow batteries comprising such composite electrolyte membranes have improved resistance to electrical short circuits. [Background technology]

[0002] Polymer electrolyte membranes (PEMs) are key components in many applications such as fuel cells, electrolyzers, redox flow batteries and humidifiers. They are semipermeable membranes made from ion exchange materials such as ionomers, which are polymers containing covalently bonded pendant ionized units. PEMs are designed to be electronic insulators and to conduct ions such as protons while having low permeability to reactants such as gases oxygen and hydrogen or other ionic species.

[0003] In polymer electrolyte membrane fuel cells (PEMFCs) and humidifiers, the PEM is part of a membrane electrode assembly (MEA). The MEA is the central component of the fuel cell where the electrochemical reactions that generate power take place. A typical MEA includes a PEM, two catalyst layers (i.e., an anode and a cathode attached to opposite sides of the PEM) and two gas diffusion layers (GDLs, attached to the outer surface of each catalyst layer, opposite the one adjacent to the PEM). The PEM separates the two reactant gas streams. On the anode side of the MEA, a fuel, such as hydrogen gas, is oxidized to separate electrons and protons. The cell is designed so that the electrons pass through an external circuit while the protons migrate through the PEM. On the cathode side, the electrons and protons react with an oxidant (i.e., oxygen or air) to produce water and heat. In this way, an electrochemical potential is maintained and electrical current can be extracted from the fuel cell to perform useful work.

[0004] Electrolyzers hydrolyze water to produce hydrogen and oxygen. The reactions that occur in electrolyzers are very similar to those in fuel cells, except that the reactions at the anode and cathode are reversed. In fuel cells, hydrogen gas is consumed at the anode, while in electrolyzers, hydrogen gas is produced at the cathode. Bipolar electrolyzers (or PEM electrolyzers) use the same type of electrolyte as PEM fuel cells. The electrolyte is a thin, solid, ionically conductive membrane that is used in place of the aqueous solution used in alkaline electrolyzers.

[0005] Redox flow batteries use two soluble redox couples as electroactive materials to store and release energy via oxidation and reduction reactions. Typically, redox flow batteries include two electrolyte reservoirs (a cathode electrolyte and an anode electrolyte) from which the electrolyte is circulated by a pump through an electrochemical cell stack. The cell stack typically includes multiple cells connected in series or parallel to allow electrochemical reactions to occur at the inert electrodes. Each cell in the stack includes an anode, a cathode, and an ion-exchange membrane separator (e.g., a polymer electrolyte membrane) that allows selective diffusion of ions (e.g., protons) across the membrane separator while preventing intermixing of the electrolyte solutions from the two reservoirs.

[0006] High selectivity (through high conductance for desired species and / or low permeability for undesired species), high durability, and low cost are all desirable qualities in a PEM. However, as a practical engineering problem, optimizing these properties often creates conflicts and trade-offs must be accepted. Reducing membrane thickness can improve selectivity by increasing the conductance for selected ions (e.g., protons). Thinner PEMs also reduce cost because more expensive ion exchange materials are used in less quantity. However, as the membrane gets thinner, permeability (e.g., to hydrogen gas or undesired ionic species) increases, compromising the selectivity gains from increased proton conduction, resulting in thinner membranes with lower selectivity than thicker membranes. In addition, thinner membranes are weaker and often lack sufficient mechanical durability for the harsh conditions of an automobile. Reducing the thickness of the polymer electrolyte membrane can make it more susceptible to damage or puncture from other electrochemical device components, potentially shortening the battery's lifespan.

[0007] One example of a mechanical weakness is the puncture of the PEM. The electrode layer, especially in RFBs, can include a microporous layer (typical pore size 1-200 microns). The microporous layer can include felt, paper, mat or woven material, among others, which can be made from a fibrous material. During PEM-electrode assembly, the electrode is compressed against the PEM. Fibrous materials such as carbon fibres that form the electrode layer can puncture the PEM upon compression. This can be particularly problematic in redox flow batteries (RFBs) where fibrous electrode layers are placed on both sides of the PEM.

[0008] Thus, PEM electrochemical devices can fail because pinholes formed by puncture damage can propagate through the polymer electrolyte membrane. Additionally, these devices can also fail if electronic current passes through the PEM and is conducted by the electrolyte through the pinholes, causing a short circuit in the system.

[0009] Thus, providing a membrane with higher proton conductivity, typically by using thinner membranes, is limited by the need to provide puncture resistance, typically by using thicker membranes.

[0010] Known approaches to improving the mechanical and puncture resistance of PEMs include protecting the PEM with a transport protection layer, however even protected PEMs can be subject to punctures when assembling the PEM during the manufacture of electrochemical devices.

[0011] Thus, a need exists for a thin composite membrane that maintains good performance and low ionic resistance while providing improved resistance to puncture by electrochemical device components and correspondingly improved resistance to electrical shorts compared to known composite membranes. Summary of the Invention

[0012] The present disclosure solves the above-mentioned problems. It has been surprisingly discovered that a composite electrolyte membrane comprising: a) at least one reinforced polymer electrolyte membrane comprising a first reinforced polymer electrolyte membrane; and b) a plurality of porous layers adjacent opposing surfaces of the first reinforced polymer electrolyte membrane, the plurality of porous layers comprising a first porous layer and a second porous layer, enhances resistance of the PEM to puncture by components of an electrochemical device during fabrication of the electrochemical device. Each of the plurality of porous layers has a plurality of pores having a pore size ranging from 5 micrometers to 5000 micrometers. Each of the plurality of pores provides one or more passages extending between a first surface and a second surface of the porous layer. Thus, the first porous layer has a plurality of pores having a pore size ranging from 5 micrometers to 5000 micrometers, the plurality of pores providing one or more passages extending between a first surface and a second surface of the first porous layer. Similarly, the second porous layer has a plurality of pores having pore sizes ranging from 5 micrometers to 5000 micrometers, the plurality of pores providing one or more passageways extending through the second porous layer between the first surface and the second surface of the second porous layer.

[0013] Moreover, such increased resistance to puncture can be achieved while maintaining low proton sheet resistance. These findings are highly beneficial because, compared to known composite electrolyte membranes, the composite electrolyte membranes described herein exhibit superior resistance to puncture by components of electrochemical devices in which the composite electrolyte membranes may be incorporated. Thus, the composite membranes described herein have superior resistance to puncture by elements of electrochemical devices during device fabrication without compromising membrane performance. The superior puncture resistance of the composite membranes described herein is evident from the improved short circuit pressure and burst pressure.

[0014] In a first aspect, a composite electrolyte membrane for an electrochemical device is provided, the composite electrolyte membrane comprising: a) at least one reinforced polymer electrolyte membrane having a first surface and an opposing second surface, wherein said at least one reinforced polymer electrolyte membrane comprises: a microporous polymer structure and an ion exchange material, wherein the ion exchange material is at least partially embedded within the microporous polymer structure to render the microporous polymer structure occlusive; and b) a plurality of porous layers including a first porous layer and a second porous layer; Including, the first porous layer having a first surface and an opposing second surface such that the first surface of the first porous layer is adjacent to the first surface of the at least one reinforced polymer electrolyte membrane, the first porous layer having a plurality of pores having pore sizes in the range of 5 micrometers to 5000 micrometers, the plurality of pores providing one or more passageways extending between the first and second surfaces of the first porous layer; The second porous layer has a first surface and an opposing second surface such that the first surface of the second porous layer is adjacent to the second surface of the at least one reinforced polymer electrolyte membrane, the second porous layer having a plurality of pores having pore sizes in the range of 5 micrometers to 5000 micrometers, the plurality of pores providing one or more passageways extending through the second porous layer between the first and second surfaces of the second porous layer.

[0015] In one embodiment, the at least one reinforced polymer electrolyte membrane comprises a first reinforced polymer electrolyte membrane having a first surface and an opposing second surface.

[0016] Each of the plurality of porous layers can have a first surface and an opposing second surface. The plurality of pores provide one or more passages extending between the first and second surfaces of the porous layers. The one or more passages can be regularly or irregularly, preferably regularly, spaced across one or both, preferably both, of the first and second surfaces of the plurality of porous layers.

[0017] In another embodiment, each of the plurality of porous layers has a thickness at 0% RH in the range of about 15 μm to about 500 μm, or about 15 μm to about 250 μm, or about 15 μm to about 200 μm, or about 15 μm to about 150 μm, or about 15 μm to about 100 μm, or about 15 μm to about 50 μm, or about 30 μm to about 500 μm, or about 30 μm to about 250 μm, or about 30 μm to about 150 μm, or about 30 μm to about 100 μm, or about 30 μm to about 50 μm, or about 50 μm to about 500 μm, or about 50 μm to about 250 μm, or about 50 μm to about 200 μm, or about 50 μm to about 150 μm, or about 50 μm to about 100 μm.

[0018] In another embodiment of the composite electrolyte membrane, the microporous polymer structure can be completely embedded within the ion exchange material.

[0019] In another embodiment of the composite electrolyte membrane, the microporous polymer structure of the reinforced polymer electrolyte membrane has a first surface and an opposite second surface, and at least one layer of ion exchange material is present on at least one of the first and second surfaces of the microporous polymer structure. Typically, a layer of ion exchange material can be present on each of the first and second surfaces of the microporous polymer structure, such that a first layer of ion exchange material is present on the first surface of the microporous polymer structure and a second layer of ion exchange material is present on the second surface of the microporous polymer structure. Preferably, a portion of one or both of the first and second porous layers is partially embedded in the layer of ion exchange material.

[0020] In another embodiment, at least one additional layer of ion exchange material is present on one or both of the first layer of ion exchange material and the second layer of ion exchange material.

[0021] In another embodiment, one or more layers of ion exchange material, for example, at least one layer of ion exchange material and / or at least one additional layer of ion exchange material, can further include at least one membrane catalyst. The at least one catalyst can include a first catalyst including one or more of Pt, Ir, Ni, Co, Pd, Ti, Sn, Ta, Nb, Sb, Pb, Mn, Ru, and Fe, oxides thereof, and mixtures thereof. In one embodiment, the at least one membrane catalyst can include a first membrane catalyst, and the first layer of ion exchange material can include a first membrane catalyst. In one embodiment, the at least one membrane catalyst can include a first membrane catalyst, and the second layer of ion exchange material can include a first membrane catalyst. In one embodiment, the at least one membrane catalyst can include a first membrane catalyst, and the at least one additional layer of ion exchange material can include a first membrane catalyst. In one embodiment, the at least one membrane catalyst can include a first membrane catalyst, and the at least one additional layer of ion exchange material can include a first membrane catalyst. In one embodiment, the at least one membrane catalyst can be present on a support, such as carbon particles.

[0022] In another embodiment, one or both of the first and second porous layers can be attached to the reinforced polymer electrolyte membrane, for example, a portion of one or both of the first and second porous layers can be partially embedded in at least one layer of ion exchange material.

[0023] In another embodiment, at least one reinforced polymer electrolyte membrane can include two or more microporous polymer structures. The two or more microporous polymer structures can include a first microporous polymer structure and a second microporous polymer structure. An adjacent pair of microporous polymer structures, such as a first microporous polymer structure and a second microporous polymer structure, can be separated by a layer of ion exchange material.

[0024] The layer of ion exchange material can have a thickness at 0% RH in the range of about 0.5 μm to about 20 μm, or about 0.5 μm to about 15 μm, or about 0.5 μm to about 12 μm, or about 0.5 μm to about 8 μm, or about 0.5 μm to about 5 μm, or about 2 μm to about 20 μm, or about 2 μm to about 15 μm, or about 2 μm to about 12 μm, or about 2 μm to about 8 μm, or about 2 μm to about 5 μm.

[0025] In one embodiment of the composite electrolyte membrane, the microporous polymer structure in which the ion exchange material is at least partially embedded to render the microporous polymer structure occlusive has a thickness in the range of about 0.5 μm to about 500 μm, or about 0.5 μm to about 250 μm, or about 0.5 μm to about 100 μm at 0% RH.

[0026] In another embodiment of the composite electrolyte membrane, such as when the composite electrolyte membrane is for use in a redox flow battery, the microporous polymer structure having an ion exchange material at least partially embedded therein to render the microporous polymer structure occlusive has a thickness at 0% RH in the range of about 0.5 μm to about 30 μm, or about 0.5 μm to about 21 μm, or about 0.5 μm to about 10 μm, or about 0.5 μm to about 8 μm, or about 0.5 μm to about 6 μm, or about 2 μm to about 30 μm, or about 2 μm to about 21 μm, or about 2 μm to about 10 μm, or about 2 μm to about 8 μm, or about 2 μm to about 6 μm.

[0027] In one embodiment of the composite electrolyte membrane, such as when the composite electrolyte membrane is for use in an electrolysis device, the microporous polymer structure having an ion exchange material at least partially embedded therein to render the microporous polymer structure occlusive has a thickness at 0% RH in the range of about 30 μm to about 100 μm, or about 30 μm to about 250 μm, or about 30 μm to about 500 μm.

[0028] In another embodiment of the composite electrolyte membrane, the microporous polymer structure can be a microporous polymer membrane.

[0029] The microporous polymer structure, such as the microporous polymer membrane, can comprise at least one fluorinated polymer. The at least one fluorinated polymer can be selected from the group comprising polytetrafluoroethylene (PTFE), poly(ethylene-co-tetrafluoroethylene) (EPTFE), expanded polytetrafluoroethylene (ePTFE), polyvinylidene fluoride (PVDF), expanded polyvinylidene fluoride (ePVDF), expanded poly(ethylene-co-tetrafluoroethylene) (eEPTFE) or a mixture thereof. Preferably, the fluorinated polymer can be perfluorinated expanded polytetrafluoroethylene (ePTFE).

[0030] Alternatively or additionally, the microporous polymer structure, such as the microporous polymer membrane, may comprise at least one hydrocarbon polymer, which may be selected from the group comprising polyethylene, polypropylene, polycarbonate, polystyrene or mixtures thereof.

[0031] In another embodiment, the microporous polymer structure may have a thickness in the range of about 2 μm to about 150 μm, or about 2 μm to about 100 μm, or about 2 μm to about 70 μm, or about 2 μm to about 40 μm, or about 2 μm to about 20 μm at 0% RH before the ion exchange material is at least partially embedded therein. It is apparent that at least partially embedding the ion exchange material within the microporous polymer structure reduces the thickness of the microporous polymer structure due to the densification of the microporous polymer structure as the pores are filled and blocked.

[0032] In another embodiment, the microporous polymer structure, prior to being at least partially embedded with the ion exchange material, has a mass of about 0.5 g / m 2 ~about 100g / m 2 , or 0.5 g / m 2 ~about 30g / m 2 , or about 0.5 g / m 2 ~Approx. 21g / m 2 , or about 0.5 g / m 2~about 10g / m 2 , or about 0.5 g / m 2 ~about 8g / m 2 , or about 0.5 g / m 2 ~about 6g / m 2 , or about 2 g / m 2 ~about 30g / m 2 , or about 2 g / m 2 ~Approx. 21g / m 2 , or about 2 g / m 2 ~about 10g / m 2 , or about 2 g / m 2 ~about 8g / m 2 , or about 2 g / m 2 ~about 6g / m 2 , or about 30 g / m 2 ~about 100g / m 2 , or about 30 g / m 2 ~about 80g / m 2 , or about 30 g / m 2 ~about 60g / m 2 The mass per area can range from 0.1 to 0.5.

[0033] In another embodiment of the composite electrolyte membrane, the ion exchange material comprises at least one ionomer. Preferably, the at least one ionomer comprises a proton conducting polymer. The proton conducting polymer may comprise perfluorosulfonic acid.

[0034] In another embodiment of the composite electrolyte membrane, the at least one ionomer has a density greater than or equal to about 1.9 g / cc at 0% relative humidity.

[0035] In another embodiment of the composite electrolyte membrane, the average equivalent volume of the ion exchange material is from about 240 cc / molar equivalent to about 1000 cc / molar equivalent, or the average equivalent volume of the ion exchange material is from about 240 cc / molar equivalent to about 650 cc / molar equivalent, or the average equivalent volume of the ion exchange material is from about 240 cc / molar equivalent to about 475 cc / molar equivalent, or the average equivalent volume of the ion exchange material is from about 350 cc / molar equivalent to about 475 cc / molar equivalent.

[0036] In another embodiment, the microporous polymer structure of the at least one reinforced polymer electrolyte membrane is partially embedded in the ion exchange material. For example, the microporous polymer structure can have a non-blocking portion proximate to the first surface, the second surface, or both surfaces of the at least one reinforced polymer electrolyte membrane. The non-blocking portion can be a portion of the microporous polymer structure that does not include any ion exchange material. Alternatively, the non-blocking portion can be a portion of the microporous polymer structure that includes a coating of ion exchange material on the inner surface of the microporous polymer structure, but does not include ion exchange material on the outer surface of the microporous polymer structure (i.e., the composite membrane does not include a layer of non-reinforced ion exchange material, but can include ion exchange material coating the surface of the inner voids, such as the inner fibrils of the microporous polymer structure). In other words, the at least one reinforced polymer electrolyte membrane does not include a surface layer of ion exchange material, also known as butter coat, on one or both of the opposing outer surfaces.

[0037] In one embodiment, the reinforced polymer electrolyte membrane can have a thickness in the range of 2 micrometers to 500 micrometers at 0% RH.

[0038] In another embodiment, the reinforced polymer electrolyte membrane has a thickness in the range of 4 micrometers to 30 micrometers at 0% RH.

[0039] In another embodiment of the composite electrolyte membrane, each of the multiple porous layers can be independently selected from woven and nonwoven materials. Examples of nonwoven materials include mesh, knit, paper, felt, mat, cloth, and the like. More preferably, the multiple porous layers are woven materials, such as woven materials having leno weave. Such woven and nonwoven materials can be made of fibers or fibrous materials, preferably fibrous polymers or metal wires or metal alloy wires. The multiple porous layers can be metal meshes, such as metal scrims.

[0040] Preferably, a porous layer of the plurality of porous layers, e.g., a fiber or fiber material forming such a layer, can comprise at least one fluorinated polymer. Preferably, the fluorinated polymer can comprise polytetrafluoroethylene (PTFE), poly(ethylene-co-tetrafluoroethylene) (EPTFE), polyvinylidene fluoride (PVDF) or a mixture thereof. More preferably, the fluorinated polymer is polytetrafluoroethylene (PTFE). In another embodiment, a porous layer of the plurality of porous layers, e.g., a fiber material forming such a layer, can comprise a hydrocarbon polymer. Preferably, the hydrocarbon polymer can comprise polyethylene, polypropylene, polycarbonate, polystyrene or a mixture thereof. In another embodiment, a porous layer of the plurality of porous layers can comprise glass fiber. In another embodiment, a porous layer of the plurality of porous layers can comprise a ceramic material. Preferably, the ceramic material can comprise silica, zirconia, alumina, calcium oxide, magnesium oxide, boron oxide, sodium oxide, potassium oxide or any mixture thereof.

[0041] In another embodiment, the pore size of a porous layer of the plurality of porous layers may preferably be in the range of 100 μm to 2000 μm, or 500 μm to 1500 μm.

[0042] In another embodiment of the composite electrolyte membrane, each of the plurality of porous layers can have a thickness at 0% RH in the range of about 15 μm to about 500 μm, or about 15 μm to about 250 μm, or about 15 μm to about 200 μm, or about 15 μm to about 150 μm, or about 15 μm to about 100 μm, or about 15 μm to about 50 μm, or about 30 μm to about 500 μm, or about 30 μm to about 250 μm, or about 30 μm to about 150 μm, or about 30 μm to about 100 μm, or about 30 μm to about 50 μm, or about 50 μm to about 500 μm, or about 50 μm to about 250 μm, or about 50 μm to about 200 μm, or about 50 μm to about 150 μm, or about 50 μm to about 100 μm.

[0043] In another embodiment of the composite electrolyte membrane, each of the plurality of porous layers has a thickness of 2.99 cm 2 The air permeability can be calculated by the formula s 2* 100 / (C1 * C2) (where s is the side length of the opening, and C1 and C2 are the vertical and horizontal spacing of the openings).

[0044] In another embodiment of the composite electrolyte membrane, each of the plurality of porous layers can have an open area porosity of 0.80 to 0.98. Preferably, each of the plurality of porous layers has an open area porosity of -0.93 to 0.97. Open area porosity can be measured by image analysis, such as ImageJ image analysis.

[0045] Each of the plurality of porous layers is preferably a non-conductive porous layer. The plurality of porous layers may be free of conductive material.

[0046] In another embodiment of the composite electrolyte membrane, the composite electrolyte membrane, i.e., at least one reinforced polymer electrolyte membrane and a plurality of porous layers, has a thickness of about 30 μm to about 1500 μm, or about 30 μm to about 1250 μm, or about 30 μm to about 1100 μm, or about 30 μm to about 800 μm, or about 30 μm to about 500 μm, or about 30 μm to about 300 μm, or about 30 μm to about 250 μm, or about 30 μm to about 150 μm, or about 60 μm to about 1500 μm, or about 60 μm to about 1250 μm, or about 60 μm to about 1 It may have a thickness in the range of 100 μm, or about 60 μm to about 800 μm, or about 60 μm to about 500 μm, or about 60 μm to about 300 μm, or about 60 μm to about 250 μm, or about 60 μm to about 150 μm, or about 100 μm to about 1500 μm, or about 100 μm to about 1250 μm, or about 100 μm to about 1100 μm, or about 100 μm to about 800 μm, or about 100 μm to about 500 μm, or about 100 μm to about 300 μm, or about 100 μm to about 250 μm, or about 100 μm to about 150 μm.

[0047] In another embodiment of the composite electrolyte membrane, the composite electrolyte membrane is a monolithic structure. For example, at least one reinforced polymer electrolyte membrane can be bonded to a plurality of porous layers. For example, at least one reinforced polymer electrolyte membrane can include a layer of ion exchange material on an outer surface of a microporous polymer structure, and one of the plurality of porous layers can be partially embedded in the layer or ion exchange material.

[0048] In another embodiment of the composite electrolyte membrane, the proton resistivity normalized tensile strength, also referred to as the proton area specific resistivity normalized tensile strength, of the composite electrolyte membrane is ≥ 2500 MPa / (ohm cm 2 ) or ≥ 3500MPa / (ohm cm 2 ) or ≥ 4000MPa / (ohm cm 2 ).

[0049] In another embodiment, the composite electrolyte membrane has a burst pressure of at least 517 kPa (75 psi), or preferably at least 689 kPa (100 psi), or more preferably at least 758 kPa (110 psi), or even more preferably at least 862 kPa (125 psi).

[0050] In another embodiment, the composite electrolyte membrane can further include at least one removable support layer attached to one or more outer surfaces of the composite electrolyte membrane, e.g., one or both of a first outer surface and a second opposing outer surface of the composite electrolyte membrane.

[0051] In a second aspect, a membrane electrode assembly for an electrochemical device is provided, the membrane electrode assembly comprising: At least one electrode including a first electrode; and a composite electrolyte membrane according to the first aspect adjacent to said at least one electrode, such that said first porous layer is between said first electrode and said at least one reinforced polymer electrolyte membrane; Includes.

[0052] In one embodiment, the at least one electrode includes a second electrode, and the second porous layer is between the second electrode and the reinforced polymer electrolyte membrane.

[0053] In another embodiment, the composite electrolyte membrane is attached to at least one electrode. In another embodiment, the composite electrolyte membrane is pressed against at least one electrode.

[0054] In another embodiment, at least one electrode comprises a fiber or fiber material. The fiber or fiber material can be electrically conductive. For example, at least one electrode can comprise a carbon fiber or a doped carbon fiber. The carbon fiber or the doped carbon fiber can have a diameter of about 8 μm to about 30 μm. Preferably, the doped carbon fiber comprises N, P, S, or B, and mixtures thereof.

[0055] In another embodiment, at least one electrode is selected from felt, paper, mat or woven material. The felt, paper, mat or woven material may be electronically conductive.

[0056] In another embodiment, at least one electrode includes an electrocatalyst layer including at least one electrocatalyst. Preferably, the at least one electrocatalyst is supported on carbon particles. Typically, the electrocatalyst layer includes at least one electrocatalyst on a support and an ion exchange material. Preferably, the at least one electrocatalyst includes one or more of Pt, Ir, Ni, Co, Pd, Ti, Sn, Ta, Nb, Sb, Pb, Mn, Ru, and Fe, oxides thereof, and mixtures thereof. The electrocatalyst layer can be electronically conductive. In some embodiments, the first electrode includes an electrocatalyst layer including at least one electrocatalyst.

[0057] In another embodiment, the electrocatalyst layer has a first surface and an opposing second surface, such that the first surface of the first porous layer contacts the first surface of the reinforced polymer electrolyte membrane and the second surface of the first porous layer contacts the first surface of the electrocatalyst layer.

[0058] In an alternative embodiment, the first electrode has a first surface and an opposing second surface, the first surface of the first porous layer contacts the first surface of the at least one reinforced polymer electrolyte membrane, and the second surface of the first porous layer contacts the first surface of the first electrode.

[0059] In another embodiment, a first surface of at least one reinforced polymer electrolyte membrane comprises a layer of an ion exchange material that includes a membrane catalyst.

[0060] Such a membrane electrode assembly can be an electrolyser membrane electrode assembly, a redox flow battery membrane electrode assembly, or a fuel cell membrane electrode assembly.

[0061] In another aspect, there is provided a fuel cell comprising a composite electrolyte membrane as described herein, or a fuel cell membrane electrode assembly as described herein.

[0062] In another aspect, there is provided a redox flow battery comprising a composite membrane as described herein, or a redox flow battery membrane electrode assembly as described herein.

[0063] In another aspect, there is provided an electrolyser comprising a composite membrane as described herein, or an electrolyser membrane electrode assembly as described herein.

[0064] The present disclosure addresses the problem of low puncture resistance of known PEMs, as discussed above. Surprisingly, it has been found that utilizing a reinforced polymer electrolyte membrane in combination with multiple porous layers increases puncture resistance while maintaining low proton sheet resistance. Surprisingly, this increased reinforcement can be achieved without increasing the amount of ion exchange material used, and can even be achieved by using a reduced amount of ion exchange material, as compared to known PEMs.

[0065] Providing a PEM that is highly resistant to puncture reduces the likelihood of failure due to electrical shorts that may occur if the composite membrane is punctured during battery assembly. It also extends the life of devices manufactured using such membranes by reducing the occurrence of shorts during use. Additionally, providing a membrane with high resistance to puncture by other electrochemical device components without increasing the thickness of the PEM components allows the ionic conductivity of the membrane to remain high, reducing manufacturing costs, as thinner membranes with comparable reinforcement require less ionomer content. [Brief description of the drawings]

[0066] In the drawings, the same reference numbers are used for the same or equivalent features of the composite electrolyte membranes disclosed herein.

[0067] [Figure 1] 1 shows a schematic diagram of a cross section of a composite electrolyte membrane according to an embodiment of the present disclosure. The composite electrolyte membrane includes a reinforced polymer electrolyte membrane and two porous layers, one disposed on each of two opposing outer surfaces of the reinforced polymer electrolyte membrane. The reinforced polymer electrolyte membrane includes a microporous polymer structure and an ion exchange material, where the ion exchange material is at least partially embedded within the microporous polymer structure to render the microporous polymer structure occlusive.

[0068] [Diagram 2] 2 shows a schematic diagram of a cross section of a composite electrolyte membrane according to an embodiment of the present disclosure. The composite electrolyte membrane has a similar structure to that of FIG. 1, except that a layer of ion exchange material is present on each of two opposing surfaces of a microporous polymer structure.

[0069] [Diagram 3]Figure 3 shows a schematic diagram of a cross section of a composite electrolyte membrane according to another embodiment. The composite membrane has a similar structure to that of Figure 2, except that there is an additional layer of ion exchange material on one of the layers of ion exchange material on one of the two opposing surfaces of the microporous polymer structure.

[0070] [Figure 4] 4 shows a schematic diagram of a cross section of a composite electrolyte membrane according to an embodiment of the present disclosure. The composite electrolyte membrane has a similar structure to that of FIG. 1, except that a layer of ion exchange material is present on each of two opposing surfaces of the microporous polymer structure, and one of these layers of ion exchange material further comprises at least one catalyst.

[0071] [Diagram 5] Figure 5 shows a schematic diagram of a cross section of a composite electrolyte membrane according to another embodiment. The composite electrolyte membrane has a similar structure to that of Figure 2, except that a layer of ion exchange material containing at least one catalyst is present on one of the layers of ion exchange material on one of two opposing surfaces of a microporous polymer structure.

[0072] [Figure 6] 6 shows a schematic diagram of a cross section of a membrane electrode assembly according to another embodiment, the membrane electrode assembly including a first electrode layer and a second electrode layer and a composite electrolyte membrane having a structure similar to that of the composite electrolyte membrane of FIG.

[0073] [Figure 7] FIG. 7 shows a bar graph comparing the average short circuit (puncture) pressure of composite electrolyte membranes having a scrim as a porous layer as disclosed herein with reinforced polymer electrolyte membranes without a porous layer and with non-reinforced polymer electrolyte membranes.

[0074] [Figure 8]FIG. 8 shows a bar graph comparing the burst pressure of a composite electrolyte membrane having a scrim as a porous layer as disclosed herein with a reinforced polymer electrolyte membrane without a porous layer and an unreinforced polymer electrolyte membrane. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0075] As used herein, the term "integral structure," when used in reference to a composite electrolyte membrane or other construct, means that, unless otherwise specified, the individual components of the composite electrolyte membrane or other construct cannot be separated without damaging or irreversibly deforming any of the individual components.

[0076] As used herein, the ion exchange material can be partially or completely embedded within the microporous polymer structure.

[0077] As used herein, a portion of a microporous polymeric structure is referred to as "occlusive" or "occluded" when the interior volume of the portion has a structure characterized by a low volume of voids, e.g., less than 10% by volume, and is highly impermeable to gases, as indicated by a Gurley number of greater than 10,000 seconds. Conversely, the interior volume of a portion of a microporous polymeric structure is referred to as "non-occlusive" or "not occluded" when the interior volume of the portion is characterized by a large volume of voids, e.g., 10% by volume or more, and is permeable to gases, as indicated by a Gurley number of less than 10,000 seconds.

[0078] Part or all of the microporous polymer structure can be made occlusive by the embedded ion exchange material. When only a part of the microporous polymer structure is occlusive, this part is preferably a layer of the microporous polymer structure, such as a layer adjacent to the microporous polymer structure or on the outer surface of the microporous polymer structure.

[0079] As used herein, the term "adjacent" is intended to mean two adjacent elements, such as microporous polymer structures, porous layers or layers of ion exchange material, that do not have elements of the same type between them, for example, when viewed along an axis perpendicular to the plane of the layers. Thus, an adjacent pair of microporous polymer material layers is two adjacent microporous polymer material layers that do not have an intervening layer of microporous polymer material between them. However, such adjacent elements of the same type can be separated by one or more elements of different types. For example, an adjacent pair of microporous polymer material layers can be separated by one or more ion exchange material layers and / or one or more porous layers.

[0080] Disclosed herein are composite electrolyte membranes for electrochemical devices, such as fuel cells, electrolyzers and redox flow batteries, which exhibit improved short circuit pressures and / or burst pressures compared to known composite membranes. Such improved short circuit pressures and / or burst pressures are believed to be a result of improved puncture resistance of the composite membrane to other components of the electrochemical device during device assembly. Without wishing to be bound by theory, providing a composite electrolyte membrane having multiple porous layers, each having multiple pores with pore sizes ranging from 5 micrometers to 5000 micrometers, disposed on opposite sides of at least one reinforced polymer electrolyte membrane significantly contributes to improved puncture resistance of the composite electrolyte membrane compared to unreinforced polymer electrolyte membranes, reinforced polymer electrolyte membranes, or combinations of unreinforced polymer electrolyte membranes and porous layers.

[0081] Furthermore, the combination of reinforced polymer electrolyte and a porous layer provides unexpected synergistic improvements in short circuit pressure and burst pressure compared to an unreinforced polymer electrolyte membrane, a reinforced polymer electrolyte membrane, or an unreinforced polymer electrolyte membrane and a porous layer.

[0082] Furthermore, when at least two porous layers are present on the opposing outer surfaces of the reinforced polymer electrolyte membrane, the total content of the microporous polymer structure of at least one reinforced polymer electrolyte membrane is increased to further improve the puncture resistance of the composite electrolyte membrane. Without wishing to be bound by theory, for any given microporous polymer content and thickness of the composite electrolyte membrane, the puncture resistance of the composite membrane can be further improved by separating the microporous polymer structure between at least two reinforced polymer layers in the composite electrolyte membrane.

[0083] In some embodiments, a composite electrolyte membrane for an electrochemical device is provided, comprising: a) at least one reinforced polymer electrolyte membrane having a first surface and an opposing second surface, wherein said at least one reinforced polymer electrolyte membrane comprises: a microporous polymer structure and an ion exchange material, said ion exchange material being at least partially embedded within said microporous polymer structure to render said microporous polymer structure occlusive; and b) a plurality of porous layers including a first porous layer and a second porous layer; Including, The first porous layer has a first surface and an opposing second surface such that the first surface of the first porous layer is adjacent to the first surface of the at least one reinforced polymer electrolyte membrane, the first porous layer has a plurality of pores having pore sizes in the range of 5 micrometers to 5000 micrometers, and the plurality of pores provide one or more passageways extending between the first and second surfaces of the first porous layer.

[0084] The embodiments are described using volume-based values ​​to provide a meaningful method of comparing the compositions between reinforced polymer electrolyte membranes containing ion exchange materials and microporous polymer structures of different densities.

[0085] In order to provide a meaningful value of the content of microporous polymer structures in the reinforced polymer electrolyte membrane, while providing these values ​​independent of the intrinsic molecular weight / matrix backbone density of the microporous polymer structures, the embodiments have been described using normalized total mass per area values. This takes into account that some embodiments may include different microporous polymer structures in the reinforced polymer electrolyte membrane layers. The content of microporous polymer structures in the reinforced polymer electrolyte membrane can also be expressed as a mass per area value, which is an appropriate measurement in embodiments that include a single type of microporous polymer structure.

[0086] The microporous polymer structure may be present in an amount of at least about 20% by volume, based on the total volume of the composite polymer electrolyte membrane.

[0087] Various definitions used in this disclosure are provided below.

[0088] As used herein, the terms "ion exchange material" and "ionomer" refer to cation exchange material, anion exchange material, or ion exchange material that contains both cation exchange and anion exchange capacity. Mixtures of ion exchange materials can also be used. The ion exchange material can be perfluorinated or hydrocarbon-based. Suitable ion exchange materials include, for example, perfluorosulfonic acid polymers, perfluorocarboxylic acid polymers, perfluorophosphonic acid polymers, styrene-based ion exchange polymers, fluorostyrene-based ion exchange polymers, polyaryletherketone ion exchange polymers, polysulfone ion exchange polymers, bis(fluoroalkylsulfonyl)imides, (fluoroalkylsulfonyl)(fluorosulfonyl)imides, polyvinyl alcohol, polyethylene oxide, divinylbenzene, metal salts with or without polymers, and mixtures thereof. In an exemplary embodiment, the ion exchange material comprises a perfluorosulfonic acid (PFSA) polymer made by copolymerizing tetrafluoroethylene and perfluorosulfonyl vinyl ester and converting them to the proton form.

[0089] As used herein, the "equivalent weight" of an ion exchange material or ionomer refers to the weight (molecular weight) of the polymer in the ion exchange material or ionomer per sulfonic acid group. Thus, a lower equivalent weight indicates a higher acid content. The equivalent weight (EW) of an ion exchange material or ionomer refers to the EW when the ion exchange material or ionomer is in the proton form at 0% RH (relative humidity) and impurities are negligible. The term "ion exchange capacity" refers to the reciprocal of the equivalent weight (1 / EW).

[0090] As used herein, the "equivalent volume" of an ion exchange material or ionomer refers to the volume of the ion exchange material or ionomer per sulfonic acid group. The equivalent volume (EV) of an ion exchange material or ionomer refers to the EV when the ionomer is pure, in the proton form at 0% relative humidity, and with negligible impurities.

[0091] As used herein, the term "microporous polymer structure" refers to a polymer matrix in which an ion exchange material or ionomer is embedded to support the ion exchange material or ionomer and provide structural integrity and durability to the resulting reinforced polymer electrolyte membrane. In some exemplary embodiments, the microporous polymer structure comprises an expanded polytetrafluoroethylene (ePTFE) membrane having a node and fibril structure. In other exemplary embodiments, the microporous polymer structure comprises a track-etched polycarbonate membrane having a smooth flat surface, high apparent density, and well-defined pore sizes.

[0092] composite membrane

[0093] As shown in Figures 1-5, a composite electrolyte membrane can include at least one reinforced polymer electrolyte membrane and multiple porous layers. As shown in these figures, a composite electrolyte membrane 100 is provided that includes reinforced polymer electrolyte membranes 110, each of which includes a microporous polymer structure 120 and an ion exchange material 125 (e.g., an ionomer) embedded in the microporous polymer structure of the reinforced polymer electrolyte membrane. That is, each of the microporous polymer structures 120 of the reinforced polymer electrolyte membranes 110 is at least partially imbibed with the ion exchange material 125. The ion exchange material 125 substantially impregnates the microporous polymer structure of the microporous polymer structure 120, rendering its interior volume substantially occlusive (i.e., the interior volume has a structure characterized by a small void volume and high impermeability to gases). For example, filling more than 90% of the internal volume of the microporous polymer structure 120 of the reinforced polymer electrolyte membrane 110 with the ion exchange material 125 will result in substantial blockage and the membrane will be characterized by a Gurley number of greater than 10,000 seconds. The ion exchange material 125 may be firmly adhered to the inner surface of the microporous polymer structure 120 of the reinforced polymer electrolyte membrane 110, for example, to the fibrils and / or nodes of the microporous polymer structure.

[0094] In the embodiment of FIG. 1, the opposing first and second surfaces of the microporous polymer structure 120 provide the opposing first and second surfaces 112 , 114 of the reinforced polymer electrolyte membrane 110 .

[0095] 2-5, the ion exchange material, in addition to being embedded in the microporous polymer structure 120 of the reinforced polymer electrolyte membrane 110, is provided on one or both of the opposing exterior surfaces of the microporous polymer structure as one or more additional layers 126, 127, 128 (e.g., also referred to as "butter coats (BC)") The portions of the ion exchange material embedded in the microporous polymer structure provide an anchoring effect for the one or more additional layers of ion exchange material.

[0096] In other embodiments, the ion exchange material is provided on only one of the exterior surfaces of the microporous polymeric structure and not on the other surface (not shown).

[0097] In other embodiments, the ion exchange material is provided only embedded in the microporous polymer structure 120, i.e., without an additional layer of ion exchange material, such as an additional butter coat (FIG. 1). Nevertheless, the composite electrolyte membrane 100 may be characterized by a microporous polymer structure that occupies more than 20% of the total volume of the composite electrolyte membrane 100, including the volume of the additional layers 126, 127, 128, if present.

[0098] 1, the first reinforced polymer electrolyte membrane 110 may be formed by embedding an ion exchange material 125 within the first microporous polymer structure 120. For example, the ion exchange material may be imbibed onto a first side of the first microporous polymer structure 120 to form the first reinforced polymer electrolyte membrane 110. In these embodiments, only a single reinforced polymer electrolyte membrane 110 is present.

[0099] In the embodiment according to Figures 2 to 5, the ion exchange material is embedded in the first microporous polymer structure 120 in a similar manner as in Figure 1. However, in the embodiment of Figures 2 to 5, the reinforced polymer electrolyte membrane 110 has two butter coats 126, 127 of ion exchange material arranged on the first and second outer surfaces of the microporous polymer structure 120. The butter coats, i.e. the first and second layers of ion exchange material, 126, 127, may contain the same ion exchange material as the ion exchange material embedded in the microporous polymer structure 120. Alternatively, the ion exchange material of one or both of the butter coats 126, 127 may be different from the ion exchange material embedded in the microporous polymer structure 120. The ion exchange material of the two butter coats 126, 127 may be the same or different. In the embodiment of Figures 2 and 4, the first and second layers 126, 127 of ion exchange material form the opposing first and second surfaces 112, 114, respectively, of the reinforced polymer electrolyte membrane 110.

[0100] 1-5, multiple porous layers are provided, including a first porous layer 130 and a second porous layer 140, which are located on opposing first and second outer surfaces, respectively, of the reinforced polymer electrolyte membrane 110. The first and second porous layers 130, 140 may be adhered to the at least one reinforced polymer electrolyte membrane 110 by the presence of an ionomer in the pores of the first and second surfaces of the microporous polymer structure 120 or by the presence of an ionomer in the layers of ion exchange material 126, 127 (FIGS. 2-5).

[0101] Thus, the first porous layer 130 is provided on a first surface of the reinforced polymer electrolyte membrane 110. The second porous layer 140 is provided on a second surface of the reinforced polymer electrolyte membrane 110, the second surface of the reinforced polymer electrolyte membrane being opposite the first surface. In these embodiments, the first porous layer 130 and the second porous layer 140 can be woven materials, such as woven materials including weft and warp fibers. Leno weave is one such preferred example of a woven material. The fibers forming the woven material can include hydrocarbon polymers, such as polyethylene, polypropylene, polycarbonate, polystyrene or mixtures thereof, or fluorinated polymers, such as polytetrafluoroethylene (PTFE), poly(ethylene-co-tetrafluoroethylene) (EPTFE), polyvinylidene fluoride (PVDF) or mixtures thereof. The woven materials of the first porous layer 130 and the second porous layer 140 can be the same or different.

[0102] In the embodiment of Figures 2-5, the reinforced polymer electrolyte membrane 110 includes first and second layers 126, 127 of ion exchange material on opposing first and second surfaces of the microporous polymer structure 120. The first and second porous layers 130, 140 are preferably partially embedded in the first and second layers 126, 127 of ion exchange material, respectively. The first and second porous layers 130, 140 can be attached to the outer surfaces 112, 114 of the reinforced polymer electrolyte membrane 110 by partially embedding the first and second porous layers 130, 140 in the non-reinforced layers 126, 127 of ion exchange material. This attachment results in a monolithic composite electrolyte membrane. This embedding can be achieved by pressing the reinforced polymer electrolyte membrane 110 and the first and / or second porous layers 130, 140 together under pressure. This may be carried out under elevated temperatures to soften the unreinforced layer of ion exchange material and / or as the unreinforced layer of ion exchange material is being formed.

[0103] In a further embodiment, not shown in the figure, the composite electrolyte membrane of FIG. 1 can be provided with a layer of ion exchange material between the first microporous polymer structure and the first porous layer. Thus, the reinforced polymer electrolyte membrane comprises a microporous polymer structure partially embedded with ion exchange material, and a layer of ion exchange material is provided on the microporous polymer structure, forming a first surface of the reinforced polymer electrolyte membrane. The first porous layer is on this first surface of the reinforced polymer electrolyte membrane. A portion of the first porous layer can be embedded in a non-reinforced layer of ion exchange material. In this way, a monolithic structure is formed that includes one reinforced polymer electrolyte membrane and the first porous layer.

[0104] Although not shown, in embodiments according to any of the constructions shown, the composite electrolyte membrane can be provided on a support layer. The support layer can include a backer layer and a release layer. The backer layer can be a polyester layer, such as polyethylene terephthalate. The release layer can be a cycloolefin copolymer (COC) layer. In some embodiments, the composite electrolyte membrane can be peeled (or separated) from the support layer before being incorporated into a membrane electrode assembly (MEA).

[0105] In the embodiment according to Figures 2-5, one or more additional layers 126, 127 of ion exchange material can be provided on one or both of the opposing exterior surfaces of the first microporous polymer structure 120. In a preferred embodiment, the one or more additional layers of ion exchange material include two or more layers, e.g., two layers of non-reinforced ion exchange material, a first layer 126 disposed on a first exterior surface of the first microporous polymer structure and a second layer 127 (i.e., butter coat) disposed on a second exterior surface of the first microporous polymer structure. The ion exchange material of the additional ion exchange material layers (i.e., butter coats) 126, 127, 128 can be the same or different, and can be the same or different from the ion exchange material embedded within the first microporous polymer structure.

[0106] In the embodiments according to Figures 2-5, the first ion exchange material can be at least partially embedded in the microporous polymer structure 120 of the first reinforced polymer electrolyte membrane 110 by absorbing the first ion exchange material into the first outer surface of the microporous polymer structure. In these embodiments, the first reinforced polymer electrolyte membrane 110 has a first layer and a second layer 126, 127 of ion exchange material disposed on the opposing first and second outer surfaces, respectively, of the microporous polymer structure 120. These two layers of ion exchange material can comprise a second ion exchange material and a third ion exchange material, respectively. These layers of ion exchange material can comprise the same ion exchange material as the first ion exchange material, such that the first ion exchange material, the second ion exchange material and the third ion exchange material are the same, or can be different from the first ion exchange material, such that the second ion exchange material and the third ion exchange material are different from the first ion exchange material. Furthermore, the second ion exchange material and the third ion exchange material forming the non-reinforced ion exchange layers can be the same or different. Additionally, the first and second layers 126, 127 of ion exchange material can have the same thickness or different thicknesses.

[0107] In some embodiments, the reinforced polymer electrolyte membrane can have two outer layers of ion exchange material on one or both of the opposing outer surfaces of the microporous polymer structure. For example, the additional layer of ion exchange material 128 can include a membrane catalyst 150, thereby forming a catalyst layer as shown in FIG. 5. In alternative embodiments, a catalyst can be present in one or both of the first and second layers of ion exchange material. The embodiment of FIG. 4 shows a membrane catalyst 150 present in the first ion exchange layer 126, thereby forming a catalyst layer. These embodiments are described in more detail below in connection with membrane electrode assemblies.

[0108] Although not specifically shown, other embodiments of the composite membrane as described herein may include two or more reinforced polymer electrolyte membranes, each of which includes a microporous polymer structure and an ion exchange material at least partially embedded within the microporous polymer material. In some embodiments, the two or more reinforced polymer electrolyte membranes may have only one outer layer of ion exchange material on one of the outer surfaces of the outermost microporous polymer structure. In some embodiments, the two or more reinforced polymer electrolyte membranes may have only one outer layer of ion exchange material on one of the outer surfaces of the outermost microporous polymer structure and may have one or more inner layers of ion exchange material between adjacent pairs of microporous polymer material layers.

[0109] In some embodiments, the two or more reinforced polymer electrolyte membranes can have two outer layers of ion exchange material on opposing exterior surfaces of each outermost microporous polymer structure, In some embodiments, the two or more reinforced polymer electrolyte membranes can have two outer layers of ion exchange material on opposing exterior surfaces of each outermost microporous polymer structure, and can have one or more inner layers of ion exchange material between adjacent microporous polymer material layers.

[0110] In some embodiments, the two or more reinforced polymer electrolyte membranes can have one or more internal layers of ion exchange material, i.e., butter coats, between each of the microporous polymer material layers. The two or more reinforced polymer electrolyte membranes may or may not have layers of ion exchange material on the outer surfaces of the two outermost microporous polymer structures.

[0111] Each reinforced polymer electrolyte membrane of the composite polymer electrolyte may contain two (or more) microporous polymer structures, which may be the same or different. In a particular reinforced polymer electrolyte membrane containing two or more microporous polymer structures, one or more internal butter coats may be located between adjacent microporous polymer structure layers. Such reinforced polymer electrolyte membranes may have one outer layer of ion exchange material on one outer surface of the outermost microporous polymer structure, or may have outer layers of ion exchange material on both outer surfaces of the outermost microporous polymer structure.

[0112] In embodiments having at least two microporous polymer structures, the two microporous polymer structures can be different. The principle of using different types of microporous polymer structures in a composite membrane construct can be applied to any of the embodiments described herein. For example, a first reinforced polymer electrolyte membrane can be formed by at least partially embedding a first ion exchange material in a first microporous polymer structure, and a second reinforced polymer electrolyte membrane can be formed by at least partially embedding a second ion exchange material in a second microporous polymer structure. In these embodiments, the first reinforced polymer electrolyte membrane layer and the second reinforced polymer electrolyte membrane are different. Thus, in the composite membranes described herein, the first microporous polymer structure can be the same or different from the second microporous polymer structure. The first ion exchange material can be the same or different from the second ion exchange material.

[0113] In additional embodiments, a portion of the microporous polymer structure 120 of the reinforced polymer electrolyte membrane 110 (e.g., one or both regions near the opposing outer surfaces of the microporous polymer structure) may comprise a non-blocking portion (i.e., an internal volume having a structure characterized by a high volume of voids and highly permeable to gas), e.g., a non-blocking layer of the microporous polymer structure that is free or substantially free of ion exchange material. The location of the non-blocking portion or layer is not limited to the regions near the opposing outer surfaces of the microporous polymer structure. As defined above, a non-blocking layer may be provided on a portion of the microporous polymer structure of any or all of the reinforced polymer electrolyte membranes.

[0114] In yet other embodiments, the non-occluded portions may include a small amount of ion exchange material present as a thin node and fibril coating on the interior surface of the microporous polymeric structure, however the amount of ion exchange material is not great enough to cause the microporous polymeric structure to become occluded, thereby forming a non-occluded portion.

[0115] In an embodiment including a first microporous polymer structure and a second microporous polymer structure that may be in direct contact with each other, the first microporous polymer structure may be fully imbibed with ion exchange material to form a blocked layer. However, the second microporous polymer structure may be mostly imbibed with ion exchange material but may include a portion or layer that is not imbibed with ion exchange material or is non-blocking. This non-blocking portion may be the layer of the second microporous polymer structure closest to the outer surface of the reinforced polymer electrolyte membrane. In the context of the present disclosure, "mostly imbibed" may mean that the microporous polymer structure is about 90% blocked with ion exchange material. In other similar embodiments (not shown), the first microporous polymer structure may include a portion or layer that is not imbibed with ion exchange material or is non-blocking, while the second microporous polymer structure may be fully imbibed with ion exchange material to form a blocked layer. The non-blocking portion or layer of the first microporous polymer structure may be close to the outer surface of the reinforced polymer electrolyte membrane.

[0116] In yet another embodiment (not shown), both the first microporous polymer structure and the second microporous polymer structure can include a portion or layer that is not imbibed with ion exchange material or is non-occluded. The non-occluded portion or layer can be disposed near one of the outer surfaces of the reinforcement layer. The partially imbibed microporous polymer structure can be about 90% occluded with ion exchange material.

[0117] In embodiments in which there is no internal buttercoat between two adjacent microporous polymer structures, the two adjacent microporous polymer structures may be in direct contact (i.e., the two adjacent microporous polymer structures may be separated by a distance d of about 0 μm).

[0118] In embodiments in which the composite membrane comprises one or more internal layers of ion exchange material between two adjacent microporous polymer structures, the two microporous polymer structures may be separated by a distance d. The distance d may be from about 1 μm to about 10 μm. The distance d may be from about 2 μm to about 8 μm. The distance d may be from about 4 μm to about 6 μm. The distance d may be from about 1 μm to about 5 μm. The distance d may be from about 5 μm to about 10 μm. The distance d may be from about 6 μm to about 8 μm. The distance d may be about 1 μm, or about 2 μm, or about 3 μm, or about 4 μm, or about 5 μm, or about 6 μm, or about 7 μm, or about 8 μm, or about 9 μm, or about 10 μm. The distance d may be the thickness of the layer of non-reinforced ion exchange material (i.e., the internal butter coat) disposed between the two adjacent microporous polymer structures.

[0119] Microporous polymer structure

[0120] The composite electrolyte membrane may include at least one reinforced polymer electrolyte membrane that includes a microporous polymer structure. For example, the composite electrolyte membrane may include 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 reinforced polymer electrolyte membranes, each of which includes a microporous polymer structure.

[0121] In one embodiment where there are at least two reinforced polymer electrolyte membranes, each membrane can be continuous. In another embodiment where there are at least two reinforced polymer electrolyte membranes, each of the at least two membranes can be discontinuous.

[0122] The appropriate microporous polymer structure will depend largely on the application the composite electrolyte membrane will be used in. The microporous polymer structure preferably has good mechanical properties, is chemically and thermally stable in the environment in which the composite membrane will be used, and is resistant to any additives used with the ion exchange material for impregnation.

[0123] As used herein, the term "microporous" refers to a structure having pores that are not visible to the naked eye. According to various optional embodiments, the pores can have an average pore size of 0.01 to 100 microns, for example, 0.05 to 20 microns, or 0.1 to 1 micron.

[0124] As used herein, the term "microporous polymer structure" is intended to refer to a layer having a thickness at 0% RH of from about 0.5 μm to about 500 μm, or from about 2 μm to about 150 μm, or from about 2 μm to about 100 μm, or from about 2 μm to about 70 μm, or from about 2 μm to about 40 μm, or from about 2 μm to about 20 μm, before the ion exchange material is at least partially embedded therein, and having an average micropore size of from about 0.05 μm to about 20 μm, e.g., 0.1 μm to 1 μm.

[0125] Suitable microporous polymer structures 120 of the reinforced polymer electrolyte membrane 110 for electrochemical applications can include porous polymer materials. The porous polymer materials can be selected from the group including fluoropolymers, chlorinated polymers, hydrocarbons, polyamides, polycarbonates, polyacrylates, polysulfones, copolyetheresters, polyethylene, polypropylene, polyvinylidene fluoride, polyaryletherketones, polybenzimidazoles, poly(ethylene-co-tetrafluoroethylene), poly(tetrafluoroethylene-co-hexafluoropropylene). In some embodiments, the microporous polymer structures 120 include perfluorinated porous polymer materials. The perfluorinated porous polymer materials can be selected from the group including polytetrafluoroethylene (PTFE), expanded polytetrafluoroethylene (ePTFE), polyvinylidene fluoride (PVDF), expanded polyvinylidene fluoride (ePVDF), expanded poly(ethylene-co-tetrafluoroethylene) (eEPTFE), and mixtures thereof.

[0126] In some embodiments, the microporous polymer structure comprises a hydrocarbon material. The hydrocarbon material can be selected from the group including polyethylene, expanded polyethylene, polypropylene, expanded polypropylene, polystyrene, polycarbonate, track-etched polycarbonate, and mixtures thereof. Examples of perfluorinated porous polymeric materials suitable for use in fuel cell applications include ePTFE made according to the teachings of U.S. Patent No. 8,757,395, which is incorporated herein by reference in its entirety, and is commercially available in various forms from W. L. Gore & Associates, Inc. (Elkton, MD).

[0127] In embodiments in which the microporous polymer structure comprises ePTFE, the total mass per area of ​​the microporous polymer structure is about 0.5 g / m based on the total area of ​​the composite electrolyte membrane. 2 ~about 100g / m 2 , or 0.5 g / m 2 ~about 30g / m 2 , or about 0.5 g / m 2 ~Approx. 21g / m 2 , or about 0.5 g / m 2 ~about 10g / m 2 , or about 0.5 g / m 2 ~about 8g / m 2 , or about 0.5 to about 6 g / m 2 , or about 2 g / m 2 ~about 30g / m 2 , or about 2 g / m 2 ~Approx. 21g / m 2 , or about 2 g / m 2 ~about 10g / m 2 , or about 2 g / m 2 ~about 8g / m 2 , or about 2 g / m 2 ~about 6g / m 2 , or about 30 g / m 2 ~about 100g / m 2 , or about 30 g / m 2 ~about 80g / m 2 , or about 30 g / m 2 ~about 60g / m 2For example, in an embodiment in which the microporous polymer structure comprises ePTFE, the total mass per area of ​​the microporous polymer structure can be about 5.5 g / m, based on the total area of ​​the composite membrane. 2 , or about 5.8 g / m 2 , or about 6 g / m 2 , or about 7 g / m 2 , or about 8 g / m 2 , or about 9 g / m 2 , or about 10 g / m 2 , or about 11 g / m 2 , or about 12 g / m 2 , or about 13 g / m 2 , or about 14 g / m 2 , or about 15 g / m 2 , or about 16 g / m 2 , or about 17 g / m 2 , or about 18 g / m 2 , or about 19 g / m 2 , or about 20 g / m 2 It is.

[0128] Ion Exchange Materials

[0129] Suitable ion exchange materials may depend on the application in which the composite electrolyte membrane is used. The ion exchange material preferably has an average equivalent volume of about 240cc / molar equivalent to about 1000cc / molar equivalent, optionally about 240cc / molar equivalent to about 650cc / molar equivalent, optionally about 240cc / molar equivalent to about 475cc / molar equivalent, optionally about 350cc / molar equivalent to about 475cc / molar equivalent. The ion exchange material can be chemically and thermally stable in the environment in which the composite electrolyte membrane is used. Ion exchange materials suitable for fuel cell applications can include cation exchange materials, anion exchange materials, or ion exchange materials that include both cation exchange and anion exchange capabilities. In some embodiments, the ion exchange material includes a proton conducting polymer or a cation exchange material. The ion exchange material can be selected from the group including perfluorocarboxylic acid polymers, perfluorophosphonic acid polymers, styrene-based ion exchange polymers, fluorostyrene-based ion exchange polymers, polyaryletherketone ion exchange polymers, polysulfone ion exchange polymers, bis(fluoroalkylsulfonyl)imides, (fluoroalkylsulfonyl)(fluorosulfonyl)imides, polyvinyl alcohol, polyethylene oxide, divinylbenzene, metal salts with or without polymers, and mixtures thereof. Examples of perfluorosulfonic acid polymers suitable for use in fuel cell applications include Nafion® (EI DuPont de Nemours, Inc., Wilmington, Del., USA), Flemion® (Asahi Glass Co., Ltd., Tokyo, Japan), Aciplex® (Asahi Chemical Co., Ltd., Tokyo, Japan), Aquivion® (SolvaySolexis SPA, Italy) and 3M™ (3M Innovative Properties Company, USA), which are commercially available perfluorosulfonic acid copolymers. Other examples of perfluorosulfonic acid polymers suitable for use in fuel cell applications include perfluorosulfonyl (co)polymers such as those described in US Pat. No. 5,463,005.

[0130] The layer of ion exchange material can have a thickness in the range of about 0.5 μm to about 20 μm, or about 0.5 μm to about 15 μm, or about 0.5 μm to about 12 μm, or about 0.5 μm to about 8 μm, or about 0.5 μm to about 5 μm, or about 2 μm to about 5 μm at 0% RH.

[0131] For use in a redox flow battery, a microporous polymer structure having an ion exchange material at least partially embedded therein to render the microporous polymer structure occlusive can have a thickness at 0% RH in the range of about 0.5 μm to about 30 μm, or about 0.5 μm to about 21 μm, or about 0.5 μm to about 10 μm, or about 0.5 μm to about 8 μm, or about 0.5 μm to about 6 μm, or about 2 μm to about 30 μm, or about 2 μm to about 21 μm, or about 2 μm to about 10 μm, or about 2 μm to about 8 μm, or about 2 μm to about 6 μm.

[0132] For use in an electrolysis device, the microporous polymer structure having the ion exchange material at least partially embedded therein to render the microporous polymer structure occlusive can have a thickness in the range of about 30 μm to about 100 μm, about 30 μm to about 250 μm, or about 30 μm to about 500 μm at 0% RH.

[0133] The reinforced polymer electrolyte membrane can have a thickness in the range of about 2 micrometers to 500 micrometers at 0% RH.

[0134] membrane catalyst

[0135] In some embodiments, one or more of the at least one layer of ion exchange material, such as the first layer 126, the second layer 127, or the at least one additional layer of ion exchange material, such as the third layer of ion exchange material 128, may further include at least one membrane catalyst 150.

[0136] Figure 4 shows an embodiment in which a first layer of ion exchange material 126 includes a membrane catalyst 150. Figure 5 shows an embodiment in which a further layer of ion exchange material 128 present on the first layer of ion exchange material 126 includes a membrane catalyst 150. The further layer of ion exchange material 128 can be a third layer of ion exchange material. Alternatively or additionally, the second layer of ion exchange material 127 can include a membrane catalyst (not shown).

[0137] The at least one membrane catalyst can include a first membrane catalyst 150 including one or more of Pt, Ir, Ni, Co, Pd, Ti, Sn, Ta, Nb, Sb, Pb, Mn, Ru, and Fe, and mixtures thereof. The at least one membrane catalyst can be present on a support, for example a particulate support, such as carbon particles.

[0138] Reinforced polymer electrolyte membrane

[0139] The reinforced polymer electrolyte membrane comprises a microporous polymer structure and an ion exchange material, the ion exchange material being at least partially embedded within the microporous polymer structure to render the microporous polymer structure occlusive. The reinforced polymer electrolyte structure may comprise one or more layers of the ion exchange material. A membrane catalyst may be present with the ion exchange material.

[0140] The reinforced polymer electrolyte membrane may have a thickness in the range of 2 μm to 500 μm at 0% RH. For example, the reinforced polymer electrolyte membrane may have a thickness in the range of 4 micrometers to 30 micrometers. Alternatively, it may have a thickness at 0% RH of about 15 μm to about 500 μm, or about 15 μm to about 250 μm, or about 15 μm to about 200 μm, or about 15 μm to about 150 μm, or about 15 μm to about 100 μm, or about 15 μm to about 50 μm, or about 30 μm to about 500 μm, or about 30 μm to about 250 μm, or about 30 μm to about 150 μm, or about 30 μm to about 100 μm, or about 30 μm to about 50 μm, or about 50 μm to about 500 μm, or about 50 μm to about 250 μm, or about 50 μm to about 200 μm, or about 50 μm to about 150 μm, or about 50 μm to about 100 μm.

[0141] Porous Layer

[0142] A suitable porous layer may depend on the application for which the composite electrolyte membrane is to be used. The porous layer should have a plurality of pores with pore sizes ranging from 5 micrometers to 5000 micrometers. The plurality of pores provide one or more passageways extending between a first surface, such as a first outer surface, of the porous layer and an opposing second surface, such as a second outer surface opposite the first surface. One of the first outer surface and the second outer surface of the first and second porous layers is adjacent to the reinforced polymer electrolyte membrane. The pores represent continuous channels extending between the outer surfaces of the porous layers such that ions can be conducted from one surface of the porous layer along the pores to the other surface of the porous layer, thereby providing an ion conduction path from the outer surface of the first porous layer, through the first porous layer, through the reinforced polymer electrolyte membrane, through the second porous layer, and to the outer surface of the second porous layer, or vice versa.

[0143] The porous layers can be independently selected from woven materials, nonwoven materials, or combinations thereof. Woven or nonwoven materials can include fibers or fibrous materials. A preferred woven material is a leno weave. Alternatively, the multiple porous layers can be nonwoven materials such as mesh, knitted materials, paper, felt, mats, or cloths. Combinations of woven and nonwoven materials are also within the scope of the present disclosure.

[0144] In some embodiments, the fibers can have aspect ratios of both length to width and length to thickness greater than about 10, and a width to thickness aspect ratio of less than about 5. The aspect ratios of the fibers, both length to thickness and length to width, can be from about 10 to about 1,000,000, 10 to about 100,000, 10 to about 1,000, 10 to about 500, 10 to about 250, 10 to about 100, about 10 to about 50, about 20 to about 1,000,000, 20 to about 1000, 20 to about 500, 20 to about 250, 20 to about 100, or even about 20 to about 50.

[0145] Nonwoven materials for the multiple porous layers can be manufactured by methods known in the art, such as meltblown fibers, spunbonding, carding, and the like.

[0146] In some embodiments, the fibers or fibrous materials forming the woven or nonwoven material of the multiple porous layers can be thermoplastic polymers. Such fibers or fibrous materials can be selected from the group including epoxy resins, phenolic resins, polyurethanes, urea-formaldehyde resins, melamine resins, polyesters such as polyethylene terephthalate, polyamides, polyethers, polycarbonates, polyimides, polysulfones, polyphenylene oxides, polyacrylates, polymethacrylates, polyolefins such as polyethylene and polypropylene, styrene and styrenic random and block copolymers such as styrene-butadiene-styrene, polyvinyl chloride, and fluorinated polymers such as polyvinylidene fluoride and polytetrafluoroethylene.

[0147] In some embodiments, the fibers or fiber materials include at least one of polyurethanes, polyesters, polyamides, polyethers, polycarbonates, polyimides, polysulfones, polyphenylene oxides, polyacrylates, polymethacrylates, polyolefins, styrenes and styrenic random and block copolymers, polyvinyl chloride, and fluorinated polymers.

[0148] In a preferred embodiment, the plurality of porous layers comprises at least one fluorinated polymer, such as a fluorinated fiber or fluorinated fibrous material. The fluorinated polymer may be selected from the group including polytetrafluoroethylene (PTFE), poly(ethylene-co-tetrafluoroethylene) (EPTFE), polyvinylidene fluoride (PVDF), and mixtures thereof. More preferably, the fluorinated polymer is polytetrafluoroethylene (PTFE).

[0149] In an alternative embodiment, the plurality of porous layers comprises a hydrocarbon polymer, such as a hydrocarbon polymer fiber or hydrocarbon polymer fiber material. The hydrocarbon polymer may be selected from the group including polyethylene, polypropylene, polycarbonate, polystyrene, and mixtures thereof.

[0150] Each of the plurality of porous layers can have a thickness at 0% RH in the range of about 15 μm to about 500 μm, or about 15 μm to about 250 μm, or about 15 μm to about 200 μm, or about 15 μm to about 150 μm, or about 15 μm to about 100 μm, or about 15 μm to about 50 μm, or about 30 μm to about 500 μm, or about 30 μm to about 250 μm, or about 30 μm to about 150 μm, or about 30 μm to about 100 μm, or about 30 μm to about 50 μm, or about 50 μm to about 500 μm, or about 50 μm to about 250 μm, or about 50 μm to about 200 μm, or about 50 μm to about 150 μm, or about 50 μm to about 100 μm.

[0151] The multiple porous layers are 2.99 cm 2 It can have an air permeability of more than 6000 liters / hour at a differential pressure of 12 mbar for an open area of ​​1.

[0152] In some embodiments, the multiple porous layers can have an open area porosity in the range of 0.80 to 0.98, preferably about 0.95.

[0153] In some embodiments, the multiple porous layers can be hydrophilic, which improves compatibility with aqueous electrolytes.

[0154] Properties of the composite electrolyte membrane

[0155] As described above, the composite electrolyte membrane comprises: a) at least one reinforced polymer electrolyte membrane comprising a microporous polymer structure and an ion exchange material at least partially embedded within the microporous polymer; and b) a plurality of porous layers, which together form distinct components that enhance the puncture resistance of the composite electrolyte membrane. Without being bound by theory, the puncture resistance of the composite electrolyte membrane may be affected by the reinforced polymer electrolyte membrane and the porous layer compared to the ion exchange material in the non-reinforced layer, optionally in combination with the porous layer, or the reinforced polymer electrolyte membrane and no porous layer.

[0156] The composite electrolyte membrane (reinforced polymer electrolyte membrane and porous layer) can have a thickness in the range of about 15 μm to about 1500 μm at 0% RH. In one embodiment, the multiple porous layers can have a thickness at 0% RH in the range of 15 μm to about 500 μm, or about 15 μm to about 250 μm, or about 15 μm to about 200 μm, or about 15 μm to about 150 μm, or about 15 μm to about 100 μm, or about 15 μm to about 50 μm, or about 30 μm to about 500 μm, or about 30 μm to about 250 μm, or about 30 μm to about 150 μm, or about 30 μm to about 100 μm, or about 30 μm to about 50 μm, or about 50 μm to about 500 μm, or about 50 μm to about 250 μm, or about 50 μm to about 200 μm, or about 50 μm to about 150 μm, or about 50 μm to about 100 μm. In another embodiment, the plurality of porous layers have a thickness of about 30 μm to about 1500 μm, or about 30 μm to about 1250 μm, or about 30 μm to about 1100 μm, or about 30 μm to about 800 μm, or about 30 μm to about 500 μm, or about 30 μm to about 300 μm, or about 30 μm to about 250 μm, or about 30 μm to about 150 μm, or about 60 μm to about 1500 μm, or about 60 μm to about 1250 μm, or about 60 μm to about 1100 μm, or about 60 μm to about 800 μm at 0% RH. or about 60 μm to about 500 μm, or about 60 μm to about 300 μm, or about 60 μm to about 250 μm, or about 60 μm to about 150 μm, or about 100 μm to about 1500 μm, or about 100 μm to about 1250 μm, or about 100 μm to about 1100 μm, or about 100 μm to about 800 μm, or about 100 μm to about 500 μm, or about 100 μm to about 300 μm, or about 100 μm to about 250 μm, or about 100 μm to about 150 μm.

[0157] The composite electrolyte membrane can have a thickness of about 15 μm, or about 16 μm, or about 17 μm, or about 18 μm, or about 19 μm, or about 20 μm, or about 21 μm, or about 22 μm, or about 23 μm, or about 24 μm, or about 25 μm, or about 30 μm, or about 35 μm, or about 40 μm, or about 45 μm, or about 50 μm, or about 55 μm, or about 60 μm, or about 65 μm, or about 70 μm, or about 75 μm at 0% RH. The composite electrolyte membrane cannot have a thickness of less than about 10 μm at 0% RH.

[0158] In some embodiments, the microporous polymer structure comprises about 2% to about 65% by volume based on the total volume of the composite electrolyte membrane, or about 15% to about 65% by volume, or about 20% to about 65% by volume, or about 30% to about 65% by volume, or about 40% to about 65% by volume, or about 50% to about 65% by volume, or about 65% to about 65% by volume, or about 25% to about 60% by volume, or about 20% to about 50% by volume, or about 20% to about 40% by volume, or about 20% to about 30% by volume, or about 40% to about 60% by volume, or about 40% to about 50% by volume based on the total volume of the composite electrolyte membrane. The microporous polymer structure may be present in an amount of about 15 volume %, or about 20 volume %, or about 25 volume %, or about 30 volume %, or about 35 volume %, or about 40 volume %, or about 45 volume %, or about 50 volume %, or about 55 volume %, or about 60 volume %, or about 65 volume %, based on the total volume of the composite electrolyte membrane.

[0159] In some embodiments, the equivalent volume of the ion exchange material is from about 240 cc / molar equivalent to about 1000 cc / molar equivalent. The ion exchange material is from about 240 g / eq to about 2000 g / eq of SO3 -In various embodiments, the acid content of the composite electrolyte membrane 100, 200, 300, 400 is greater than 1.2 meq / cc at 0% relative humidity, such as greater than 1.2 meq / cc up to 3.5 meq / cc. In various embodiments, the thickness of the composite electrolyte membrane 100, 200, 300, 400 at 0% RH is about 4 μm to about 115 μm, or about 4 μm to about 50 μm, or about 4 μm to about 40 μm, or about 4 μm to about 36 μm, or about 4 μm to about 30 μm, or about 4 μm to about 25 μm, or about 4 μm to about 15 μm, or about 4 μm to about 8 μm, or about 10 μm to about 115 μm, or about 10 μm to about 50 μm, or about 10 μm to about 40 μm, or about 10 μm to about 36 μm, or about 10 μm to about 30 μm, or about 10 μm to about 25 μm, or about 10 μm to about 15 μm. Specifically, according to embodiments, the composite electrolyte membrane 100, 200, 300, 400 has a thickness of about 4 μm to about 115 μm, and the acid content of the composite membrane 100, 200, 300, 400 ranges from greater than 1.2 to 3.5 meq / cc.

[0160] The volume percent of the microporous polymer structure in the composite refers to the space occupied by the nodes and fibrils of the microporous polymer structure without the ionomer. Therefore, the volume percent of the microporous polymer structure in the composite is different from the absorbent layer that contains the ionomer. The volume percent of the microporous polymer structure in the composite is affected by humidity. Therefore, the experiments described below with respect to volume percent are performed under dry conditions (e.g., 0% relative humidity (RH)).

[0161] In some embodiments, the normalized total content of the microporous polymer structures within the composite membrane is at least about 3×10 based on the total area of ​​the composite membrane. -6 m, or approximately 3.5 × 10 -6 m, or approximately 4 × 10 -6 m, or approximately 4.5 × 10 -6 m, or approximately 5 × 10 -6 m, or approximately 5.5 × 10 -6 m, or approximately 6 × 10 -6 m, or approximately 6.5 × 10 -6m, or approximately 7 × 10 -6 m, or approximately 8 × 10 -6 m, or approximately 8.5 × 10 -6 m, or approximately 9 x 10 -6 It can be m.

[0162] The equivalent weight of ion exchange materials is also affected by humidity, therefore the experiments described below regarding equivalent weight are carried out under dry conditions (e.g., 0% relative humidity (RH)), an ideal condition in which the presence of water does not affect the equivalent volume values ​​and meaningful comparisons can be made between different ionomers.

[0163] As discussed above, it is surprising and unexpected that by providing a reinforced polymer electrolyte membrane in combination with a porous layer, the puncture resistance of the composite electrolyte membrane is dramatically improved.

[0164] The composite electrolyte membrane may have an average burst pressure of at least about 40 psi when measured by the Average Burst Pressure Test described below. For example, the composite electrolyte membrane may have an average burst pressure of at least about 60 psi, or at least about 80 psi, or at least about 100 psi when measured by the Average Burst Pressure Test described below. The composite electrolyte membrane may have an average burst pressure of less than about 200 psi when measured by the Average Burst Pressure Test described below.

[0165] The composite membrane can have an average short circuit pressure of at least about 130 psi when measured by the Average Short Circuit Pressure Test described below. For example, the composite electrolyte membrane can have an average short circuit pressure of about 140 psi or more, about 200 psi or more, or about 300 psi or more, or about 350 psi or more when measured by the Average Short Circuit Pressure Test described below. The composite membrane can have an average short circuit pressure of less than about 800 psi when measured by the Average Short Circuit Pressure Test described below.

[0166] The composite membrane can have an average burst pressure of about 150 psi or more, or about 200 psi or more, or about 250 psi or more, or about 300 psi or more, or about 350 psi or more, or about 400 psi or more, or about 450 psi or more, or about 500 psi or more, as measured by the Average Puncture Pressure Burst Test described below.

[0167] Preparation method

[0168] The reinforced polymer electrolyte membrane can be prepared according to the methods described in Figures 4A, 4B and 4C of WO 2018 / 231232 A1, the contents of which are incorporated herein in their entirety.

[0169] In one embodiment, the at least one reinforced polymer electrolyte membrane can include a first reinforced polymer electrolyte membrane formed by a method including at least the following steps. - providing a support structure; - applying a first ion exchange material solution to a support structure as a layer of controlled thickness by a single pass or multiple pass ion exchange material coating technique, said first ion exchange material solution comprising a first ion exchange material dissolved in a solvent; - laminating a microporous polymer structure over at least a portion of the first ion exchange material solution to provide a treated microporous polymer structure; and - drying the treated microporous polymer structure to provide a first reinforced polymer electrolyte membrane having a first ion exchange material firmly adhered to the inner surface of the microporous polymer structure. The ion exchange material is at least partially embedded in the microporous polymer structure rendering the microporous polymer structure occlusive. The first reinforced polymer electrolyte membrane can include a layer of a first ion exchange material on a surface of the microporous polymer structure.

[0170] In another embodiment, the at least one reinforced polymer electrolyte membrane can include a first reinforced polymer electrolyte membrane formed by a method including at least the following steps. - providing a support structure; - applying a first ion exchange material solution to a support structure as a layer of controlled thickness by a single pass or multiple pass ion exchange coating technique, where the first ion exchange material solution comprises a first ion exchange material dissolved in a solvent; - laminating a microporous polymer structure over at least a portion of the first ion exchange material solution to provide a treated microporous polymer structure; - optionally drying the treated microporous polymer structure to provide a dry composite material in which the first ion exchange material is firmly adhered to the inner surface of the microporous polymer structure; - coating a second ion exchange material solution onto the treated microporous polymer structure, or optionally drying the composite as a layer of controlled thickness by single or multiple pass ion exchange material coating techniques, to provide a structure comprising the second ion exchange material dissolved in a solvent; and - drying the structure to provide a first reinforced polymer electrolyte membrane. The first reinforced polymer electrolyte membrane includes a layer of a first ion exchange material on a first surface of the microporous polymer structure and a layer of a second ion exchange material on an opposing second surface of the microporous polymer structure.

[0171] In some embodiments, the support structure can be: - a woven material selected from scrims made of woven fibers of expanded porous polytetrafluoroethylene, webs made of extruded or oriented polypropylene or polypropylene netting, and woven materials of polypropylene and polyester, or - a nonwoven material selected from spunbond polypropylene, or - a web of polyethylene ("PE"), polystyrene ("PS"), cyclic olefin copolymer ("COC"), cyclic olefin polymer ("COP"), fluorinated ethylene propylene ("FEP"), perfluoroalkoxyalkane ("PFA"), ethylene tetrafluoroethylene ("ETFE"), polyvinylidene fluoride ("PVDF"), polyetherimide ("PEI"), polysulfone ("PSU"), polyethersulfone ("PES"), polyphenylene oxide ("PPO"), polyphenylether ("PPE"), polymethylpentene ("PMP"), polyethylene terephthalate ("PET"), or polycarbonate ("PC").

[0172] In some embodiments, the support structure further comprises a protective layer selected from polyethylene (PE), polystyrene ("PS"), cyclic olefin copolymer ("COC"), cyclic olefin polymer ("COP"), fluorinated ethylene propylene ("FEP"), perfluoroalkoxyalkane ("PFA"), ethylene tetrafluoroethylene ("ETFE"), polyvinylidene fluoride ("PVDF"), polyetherimide ("PEI"), polysulfone ("PSU"), polyethersulfone ("PES"), polyphenylene oxide ("PPO"), polyphenylether ("PPE"), polymethylpentene ("PMP"), polyethylene terephthalate ("PET"), or polycarbonate ("PC").

[0173] In some embodiments, the single pass or multiple pass ion exchange material coating technique is selected from forward roll coating, reverse roll coating, gravure coating, doctor coating, kiss coating, slot die coating, slide die coating, dipping, brushing, painting, and spraying. As used herein, multiple pass ion exchange material coating technique includes at least two sequential applications of an ion exchange material solution comprising an ion exchange material dissolved in a solvent.

[0174] In some embodiments, drying involves heating at a temperature above 60° C., for example in an oven.

[0175] In some embodiments, the second ion exchange material is the same as the first ion exchange material, while in other embodiments, the second ion exchange material is different from the first ion exchange material.

[0176] In another embodiment, the at least one reinforced polymer electrolyte membrane can include a first reinforced polymer electrolyte membrane and a second reinforced polymer electrolyte membrane formed by a method including at least the following steps: - providing a support structure; - applying a first ion exchange material solution to said support structure as a layer of controlled thickness by single pass or multiple pass ion exchange material coating techniques, where the first ion exchange material solution comprises a first ion exchange material dissolved in a solvent; - laminating a first microporous polymer structure over at least a portion of the first ion exchange material solution to provide a first treated microporous polymer structure; - optionally drying the first treated microporous polymer structure to provide a first dried composite material, wherein said first ion exchange material is firmly adhered to an interior membrane surface of said first microporous polymer structure; - coating a second ion exchange material solution onto the first treated microporous polymer structure or optionally onto the first dry composite material as a layer of controlled thickness in a single pass or multiple pass ion exchange material coating technique, wherein said second ion exchange material solution comprises a second ion exchange material solution dissolved in a solvent; - laminating a second microporous polymer structure over at least a portion of the second ion exchange material solution to provide a second treated microporous polymer structure; - optionally drying the second treated microporous polymer structure to provide a second dried composite material, wherein said second ion exchange material is firmly adhered to the interior membrane surface of said second microporous polymer structure; - coating a third ion exchange material solution onto the second treated microporous polymer structure or optionally onto the second dried microporous polymer structure as a layer of controlled thickness by single or multiple pass ionomeric coating techniques to provide a third treated microporous polymer structure, wherein said third ion exchange material solution comprises a third ion exchange material dissolved in a solvent; and drying the third treated microporous polymer structure to provide a first reinforced polymer electrolyte membrane.

[0177] The ion exchange material is at least partially embedded within the microporous polymer structure, rendering the microporous polymer structure occlusive. The at least one reinforced polymer electrolyte membrane can include a first reinforced polymer electrolyte membrane comprising a layer of a first ion exchange material on a first surface of the first microporous polymer structure and a layer of a second ion exchange material on an opposite second surface of the first microporous polymer structure, and a second reinforced polymer electrolyte membrane comprising a layer of a second ion exchange material on a first surface of the second microporous polymer structure and a layer of a third ion exchange material on an opposite second surface of the second microporous polymer structure. Thus, the layer of the second ion exchange material is between the first microporous polymer structure and the second microporous polymer structure.

[0178] In some embodiments, the first ion exchange material, the second ion exchange material, and the third ion exchange material can independently be the same or different.

[0179] In some embodiments, the definition of the substrate, the single pass or multiple pass coating technique, and the heating step can be as described above.

[0180] In one embodiment, the composite electrolyte membrane may be formed by a method including at least the following steps. providing at least one reinforced polymer electrolyte membrane comprising a first reinforced polymer electrolyte membrane having a first surface and an opposing second surface; - applying to the first reinforced polymer electrolyte membrane a first porous layer having a first surface and an opposing second surface such that the first surface of the first porous layer is adjacent to the first surface of the first reinforced polymer electrolyte membrane; and applying a second porous layer to the first reinforced polymer electrolyte membrane, the second porous layer having a first surface and an opposing second surface, such that the first surface of the second porous layer is adjacent to the second surface of the first reinforced polymer electrolyte membrane, to provide a composite electrolyte membrane.

[0181] In one embodiment, the first reinforced polymer electrolyte membrane can include a first layer and a second layer of ion exchange material on opposing first and second surfaces of the microporous polymer structure, whereby the attaching step includes partially embedding the first and second porous layers in the first and second layers of ion exchange material. In this manner, the first and second porous layers are attached to the first reinforced polymer electrolyte membrane. For example, embedding can be accomplished by pressing the first reinforced polymer electrolyte membrane and the first and / or second porous layers together under pressure. This can be performed with heating to soften the first and / or second layers of ion exchange material, and / or pressing can be performed during formation of the first and / or second layers of ion exchange material.

[0182] In another embodiment, the step of providing at least one reinforced polymer electrolyte membrane comprising the first reinforced polymer electrolyte membrane can be one of the methods of forming at least one reinforced polymer electrolyte membrane described above.

[0183] membrane electrode assembly

[0184] The composite electrolyte membrane disclosed herein can also be incorporated into a membrane electrode assembly. In the embodiment shown in FIG. 6, a membrane electrode assembly 200 for an electrochemical device is provided, comprising at least one electrode, including a first electrode 160, and a composite electrolyte membrane as described herein. The composite electrolyte membrane is adjacent to the at least one electrode, such that the first porous layer 130 is between the first electrode 160 and the at least one reinforced polymer electrolyte membrane 110. In this way, the at least one reinforced polymer electrolyte membrane 110 is protected from damage by the first electrode 160 by the intervening first porous layer 130.

[0185] In some embodiments of the membrane electrode assembly 200, the at least one electrode may further include a second electrode 170. The second porous layer 140 may be located between the second electrode 170 and the reinforced polymer electrolyte membrane 110. In this manner, the at least one reinforced polymer electrolyte membrane 110 is protected from damage by the second electrode 170 by the intervening second porous layer 140.

[0186] In some embodiments, the composite electrolyte membrane can be attached to at least one electrode, for example, the composite electrolyte membrane and the at least one electrode can be pressed together.

[0187] In some embodiments, at least one electrode may include fibers or fiber materials. Such fibers or fiber materials may cause damage or penetration of at least one reinforced polymer electrolyte membrane by the fibers or fiber materials. Examples of fibers or fiber materials forming the electrodes include carbon fibers or doped carbon fibers. Suitable carbon fibers or doped carbon fibers may have a diameter of about 8 μm to about 30 μm. Doped carbon fibers may include N, P, S, or B and mixtures thereof.

[0188] The at least one electrode may be selected from felt, paper, mat or woven materials.

[0189] The combination of the reinforced polymer electrolyte membrane 110 disposed between the first and second porous layers 130, 140 improves protection of the reinforced polymer electrolyte membrane against puncture by fibers from the first and second electrodes 160, 170. This is evidenced by significantly improved burst pressure and short circuit pressure of cells including such membrane electrode assemblies when compared to unreinforced polymer electrolyte membranes, unreinforced polymer electrolyte membranes with a porous layer, or reinforced polymer electrolyte membranes without a porous layer.

[0190] Such a membrane electrode assembly 200 can be used as a membrane electrode assembly for a redox flow battery.

[0191] At least one electrode may include an electrocatalyst layer (not shown) that includes at least one electrocatalyst. The electrocatalyst layer may further include an ion exchange material as described above. The at least one electrocatalyst may be a supported electrocatalyst, such as an electrocatalyst on a particle support, such as an electrocatalyst on carbon particles. In some embodiments, the electrocatalyst layer is electronically conductive due to the presence of another electronically conductive material, such as carbon particles or conductive particles, typically metal particles, such as metal electrocatalyst particles. Alternatively, the electrocatalyst layer may be electronically conductive due to the presence of metal electrocatalyst particles.

[0192] At least one electrocatalyst of the electrocatalyst layer can include one or more of Pt, Ir, Ni, Co, Pd, Ti, Sn, Ta, Nb, Sb, Pb, Mn, Ru, and Fe, oxides and mixtures thereof.

[0193] In some embodiments, the at least one electrocatalyst-containing electrocatalyst layer can be a first electrocatalyst layer having a first surface and an opposing second surface, such that the first surface of the first porous layer is in contact with the first surface of the reinforced polymer electrolyte membrane and the second surface of the first porous layer is in contact with the first surface of the first electrocatalyst layer. Preferably, the first surface of the at least one reinforced polymer electrolyte membrane can include a layer of ion exchange material comprising a membrane catalyst as described above as a component of at least one ion exchange material layer of the composite electrolyte membrane.

[0194] Alternatively or additionally, the further electrocatalyst layer comprising at least one electrocatalyst can be a second electrocatalyst layer having a first surface and an opposite second surface, such that the first surface of the second porous layer is in contact with the second surface of the reinforced polymer electrolyte membrane and the second surface of the second porous layer is in contact with the first surface of the second electrocatalyst layer. Preferably, the second surface of the at least one reinforced polymer electrolyte membrane can comprise a layer of ion exchange material comprising a membrane catalyst as described above, as a component of at least one ion exchange material layer of the composite electrolyte membrane.

[0195] In some embodiments, the first electrode has a first surface and an opposing second surface as a first electrode layer, the first surface of the first porous layer being in contact with a first surface of at least one reinforced polymer electrolyte membrane, and the second surface of the first porous layer being in contact with a first surface of the first electrode. Preferably, the first surface of the at least one reinforced polymer electrolyte membrane can include a layer of ion exchange material comprising a membrane catalyst as described above as a component of at least one ion exchange material layer of the composite electrolyte membrane.

[0196] Alternatively or additionally, a second electrode having a first surface and an opposite second surface may be provided as a second electrode layer, the first surface of the second porous layer being in contact with the first surface of the at least one reinforced polymer electrolyte membrane and the second surface of the second porous layer being in contact with the first surface of the second electrode. Preferably, the second surface of the at least one reinforced polymer electrolyte membrane may comprise a layer of ion exchange material comprising a membrane catalyst as described above, as a component of at least one ion exchange material layer of the composite electrolyte membrane.

[0197] Such a membrane electrode assembly can be used as a membrane electrode assembly in an electrolyser or a fuel cell.

[0198] When the membrane electrode assembly is a fuel cell membrane electrode assembly, the first and second electrocatalyst layers can have a pore size of about 100 nm or less. The first and second electrocatalyst layers can independently include one or more of an ion exchange material, a catalyst support such as carbon black, and a catalyst supported on the catalyst support such as platinum.

[0199] Redox flow batteries, fuel cells and electrolyzers comprising such membrane electrode assemblies are also within the scope of this disclosure. EXAMPLES

[0200] example

[0201] Test procedures and measurement protocols used in the examples

[0202] Unless otherwise stated, temperature is 23°C measured at 0% relative humidity.

[0203] Bubble Point

[0204] Bubble point was measured according to the procedure of ASTM F316-86. Isopropyl alcohol was used as the wetting fluid to fill the pores of the specimen. The bubble point is the pressure of air required to produce a first continuous stream of bubbles detectable by the bubbles rising through a layer of isopropyl alcohol covering a microporous polymer matrix. This measurement provides an estimate of the maximum pore size.

[0205] Non-contact thickness

[0206] A sample of the microporous polymer structure was placed on a flat, smooth metal anvil and tensioned to remove wrinkles. The height of the microporous polymer structure on the anvil was measured and recorded using a non-contact Keyence LS-7010M digital micrometer. The height of the anvil without the microporous polymer structure was then recorded. The thickness of the microporous polymer structure was taken as the difference between the micrometer readings with and without the microporous structure on the anvil.

[0207] Mass per area

[0208] Each microporous polymer structure was stretched sufficiently to eliminate wrinkles and then cut using a die to a length of 10 cm. 2 A small piece of 10cm was cut off. 2 The weight of the pieces was measured on a conventional laboratory scale. The mass per area (M / A) was then calculated as the ratio of the measured mass to the known area. This procedure was repeated twice and the average M / A was calculated.

[0209] Apparent density of microporous polymer structures

[0210] The apparent density of the microporous polymer structure was calculated using the non-contact thickness and mass per area data using the following formula:

number

[0211] Porosity of microporous polymer structures

[0212] The porosity of the microporous polymer structure was calculated using the apparent density and skeletal density data using the following formula:

number

[0213] Solids concentration of the ion exchange material (IEM) solution

[0214] In this specification, the terms "solution" and "dispersion" are used interchangeably when referring to ion exchange materials (IEMs). This test procedure is appropriate for solutions in which the IEMs are in the proton form and other solids are present in negligible amounts. A volume of 2 cubic centimeters of IEM solution was drawn into a syringe and the mass of the syringe containing the solution was measured by the balance of a solids analyzer (obtained from CEM Corporation, USA). The mass of two sheets of glass fiber paper (obtained from CEM Corporation, USA) was also measured and recorded. The IEM solution was then deposited from the syringe onto two layers of glass fiber paper. The glass fiber paper containing the ionomer solution was placed in the solids analyzer and heated to 160°C to remove the solvent liquid. The mass of the glass fiber paper and the residual solids was recorded once it stopped changing with increasing temperature and time. The residual IEM is assumed to be water-free (i.e., this is the mass of the ionomer corresponding to 0% RH). The mass of the empty syringe was then measured using the same balance as before and recorded. The ionomer solids content in the solution was calculated according to the following formula:

number

[0215] Equivalent weight (EW) of IEM

[0216] The following test procedure is appropriate for IEMs containing a single ionomer resin or a mixture of ionomer resins that are in the proton form (i.e., contain negligible amounts of other cations) and in solution with negligible amounts of other ionic species, including protonic acids and dissociated salts. If these conditions are not met, the solution must be purified from ionic impurities prior to testing according to appropriate procedures known to those skilled in the art, or the impurities must be characterized and their effect on the results of the EW test corrected.

[0217] As used herein, the EW of an IEM refers to when the IEM is in the proton form at 0% RH with negligible impurities. The IEM may comprise a single ionomer or a mixture of ionomers in the proton form. An amount of IEM solution having a solids concentration determined as above and containing 0.2 grams of solids was poured into a plastic cup. The mass of the ionomer solution was measured via a conventional laboratory scale (obtained from Mettler-Toledo, USA). Next, 5 ml of deionized water and 5 ml of 200 proof denatured ethanol (SDA 3C, Sigma Aldrich, USA) are added to the ionomer solution in the cup. Then, 55 ml of 2N aqueous sodium chloride solution was added to the IEM solution. The sample was then allowed to equilibrate under constant stirring for 15 minutes. After the equilibration step, the sample was titrated with 1N sodium hydroxide solution. The volume of 1N sodium hydroxide solution required to neutralize the sample solution to a pH value of 7 was recorded. The EW of the IEM (EW IEM ) was calculated as follows:

number

[0218] When multiple IEMs were combined to form a composite membrane, the average EW of the IEMs in the composite membrane was calculated using the following formula:

number

[0219] In the above formula, the mass fraction of each IEM is relative to the total amount of all IEMs. This formula was used for both composite membranes containing ionomer blends and composite membranes containing multiple ionomer layers.

[0220] Equivalent Volume (EV) of Ion Exchange Material

[0221] As used herein, the equivalent volume of an IEM refers to the EV when the IEM is pure and in its proton form at 0% RH with negligible impurities. The EV was calculated according to the following formula:

number

[0222] The equivalent weight of each IEM was determined according to the procedure described above. The IEM used in these applications was a perfluorosulfonic acid ionomer resin, and the bulk density of the perfluorosulfonic acid ionomer resin was 1.9 g / cc at 0% RH.

[0223] Composite electrolyte membrane thickness

[0224] The composite electrolyte film was equilibrated in the thickness measurement chamber for at least 1 hour before the thickness was measured. The composite electrolyte film was left attached to the substrate on which it was coated. For each sample, the composite electrolyte film on the coated substrate was placed on a smooth, flat, and level marble slab. A thickness gauge (obtained from Heidenhain Corporation, USA) was contacted to the composite film and height readings of the gauge were recorded at six different spots arranged in a grid pattern on the film. The sample was then removed from the substrate and the gauge was contacted to the substrate and height readings were again recorded at the same six spots. The thickness of the composite film at a given relative humidity (RH) in the chamber was calculated as the difference between the gauge height readings with and without the composite film present. The local RH was measured using a RH probe (obtained from Fluke Corporation). The thickness at 0% RH was calculated using the following general formula:

number

[0225] In the above equation, the parameter λ corresponds to the water uptake of the ion exchange material in moles of water per mole of acid groups at a specified RH. For the PFSA ionomers, the λ value at any RH in the gas phase between 0 and 100% was calculated according to the following equation:

number

[0226] Microporous polymer matrix (MPM) volume content of composite electrolyte membranes

[0227] The volume percentage of the microporous polymer structure in each composite membrane was calculated according to the following formula:

number

[0228] The microporous polymer matrices used in these examples were ePTFE and track-etched porous polycarbonate, with the matrix skeletal density of ePTFE being 2.25 g / cc and the matrix skeletal density of track-etched porous polycarbonate being 1.20 g / cc.

[0229] Acid content of composite electrolyte membrane

[0230] The acid content of the composite membrane was calculated according to the following formula:

number

[0231] Burst pressure test of composite electrolyte membrane

[0232] The mechanical strength of the composite electrolyte membrane prepared according to the present invention was measured by applying a load pressure to the sample.

[0233] A membrane sample is clamped between two steel plates with a 10 mm aperture in the upper plate. The system is pressurized from below, exerting a biaxial stress on the membrane as it domes through the aperture. The pressure is increased in 5 psi increments, held for 5 seconds between each level, until the membrane fails. The pressure at which failure occurs is recorded as the burst pressure. This procedure is repeated four times and the average burst pressure and standard deviation are calculated.

[0234] Average puncture pressure burst test

[0235] The sample was placed between two porous carbon electrodes (Sigracet 39AA carbon paper) and loaded into an Instron model 5542 equipped with an electrically insulated, gold-plated, cylindrical platen, 14 mm in diameter. The area of ​​the sample and electrodes was large compared to the platens and extended beyond the platens to eliminate edge effects during puncture. The sample area was large compared to the electrode area to prevent the electrodes from touching and creating an electronic short that does not pass through the sample. The electrical resistance across the membrane is measured by a Keithley 580 microohmmeter connected to the upper and lower platens. While a compressive mechanical load was applied to the sample, the upper platen was lowered at a rate of 1 mm / min at ambient conditions, constantly recording the electrical resistance measured across the sample until 444.8 N (100 lbf) was applied. Higher compressive pressures can be obtained in this case by using alternative fixtures or by reducing the active area of ​​the platens. Membrane puncture was defined as the pressure at which electrical resistance dropped below 18,000 ohms, representing physical contact of the electrode or electrode fibers through the sample. Five replicates were tested for each sample, and the average of the five tests is reported as the average puncture pressure. Puncture pressure is dependent on the electrode material and may be significantly increased or decreased with the use of alternative electrode materials.

number

[0236] example

[0237] The composite electrolyte membranes of the present disclosure may be better understood with reference to the following non-limiting examples.

[0238] The properties of the composite membranes, such as acid content, volume, puncture resistance, and other properties, as well as the test procedures and measurement protocols, were determined as described above. Table 1 shows the properties of the composite membranes according to embodiments of the invention and comparative examples. Table 2 shows the properties of the microporous polymer structures used in the various test procedures in a series of five examples and comparative examples according to some aspects of the invention.

[0239] All examples are ion exchange materials made according to aspects of the present disclosure.

[0240] All ion exchange materials used in the following examples are perfluorosulfonic acid (PFSA) based ionomers with equivalent weights (EW) specified in Table 1. All ionomers prior to fabrication of the composite membranes were in the form of solutions based on mixtures of water and ethanol as solvents with water content in the solvent phase less than 50%.

[0241] The composite membrane of the present disclosure was produced using commonly known ion exchange materials. A preferred example is a cation exchange material represented by the following general formula (a:b=1:1 to 9:1, n=0, 1 or 2), where X is -O-(CF2C(CF3)FO) n -CF2CF2SO3H is the unit -(CF2CF2) a -and-(CF2CXF) b The solution is obtained by dispersing or dissolving a solid PFSA ionomer containing - in a solvent. [ka]

[0242] In some embodiments, the solvent is selected from the group consisting of water, alcohols such as methanol, ethanol, propanol, n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol, and tert-butyl alcohol, pentanol and its isomers, hexanol and its isomers, hydrocarbon solvents such as n-hexane, ether solvents such as tetrahydrofuran and dioxane, sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, formamide solvents such as N,N-dimethylformamide and N,N-diethylformamide, acetamide solvents such as N,N-dimethylacetamide and N,N-diethylacetamide, pyrrolidone solvents such as N-methyl-2-pyrrolidone and N-vinyl-2-pyrrolidone, 1,1,2,2-tetrachloroethane, 1,1,1,2-tetrachloroethane, 1,1,1-trichloroethane, 1,2-dichloroethane, trichloroethylene, tetrachloroethylene, dichloromethane, and chloroform. In the present disclosure, the solvent is optionally selected from the group consisting of water, methanol, ethanol, and propanol. Water and the above solvents may be used alone or in combination of two or more.

[0243] Comparative Example 1

[0244] Mass per area is 4g / m 2An ePTFE membrane 1, with a thickness of 13.3 μm, apparent density of 0.26 g / cc, and bubble point of 55.5 psi, was pulled by hand to remove wrinkles and restrained in this state by a metal frame. A first laydown of PSFA solution (obtained from Asahi Glass Co., Ltd., Japan) with a solution composition of EV=379 cc / molar equivalent, 34.87% water, 48.09% ethanol, and 17.04% solids was then coated onto the top surface of the polymer sheet substrate. The polymer sheet substrate (obtained from Daicel Value Coating Co., Ltd., Japan) contained a protective layer of PET and cyclic olefin copolymer (COC) and was oriented with the COC side facing up. The IEM (PFSA solution) coating was achieved using a Meyer bar with a theoretical wet coating thickness of 3 mils. The ePTFE membrane 1, which had been previously restrained on a metal frame, was laminated to the coating while it was still wet, allowing the IEM solution to be absorbed into the pores. The composite was then dried at a temperature of 165°C in an air-filled convection oven. Upon drying, the IEM was fully absorbed into the microporous polymer structure (ePTFE membrane). The IEM also formed a layer between the bottom surface of the microporous polymer substrate and the polymer sheet substrate. During the second laydown, the same IEM was coated onto the top surface of the composite (opposite surface of the polymer sheet substrate) using a drawdown bar with a theoretical wet coating thickness of 3 mils, with a solution composition of 38% water, 57.7% ethanol, and 4.3% solids. The composite was then dried again at 165°C. At this point, the composite was nearly transparent, indicating that the microporous polymer structure was fully impregnated. The multilayer composite membrane was completely occluded, with a layer of IEM on both sides of the microporous polymer matrix. The resulting multilayer composite membrane had a thickness of 6.5 micrometers at 0% RH, 28% by volume occupied by the microporous polymer structure, and an acid content of 1.9 meq / cc. The multilayer composite membrane does not have a porous layer.

[0245] Example 1

[0246] Mass per area is 4g / m 2An ePTFE membrane with a thickness of 13.3 μm, apparent density of 0.26 g / cc, and bubble point of 55.5 psi was pulled by hand to remove wrinkles and restrained in this state on a metal frame. A first laydown of PSFA solution (obtained from Asahi Glass Co., Ltd., Japan) with a solution composition of EV=379 cc / molar equivalent, 34.87% water, 48.09% ethanol, and 17.04% solids was then coated onto the top surface of the polymer sheet substrate. The polymer sheet substrate (obtained from Daicel Value Coating Co., Ltd., Japan) contained a protective layer of PET and cyclic olefin copolymer (COC) and was oriented with the COC side facing up. The IEM (PFSA solution) coating was achieved using a Meyer bar with a theoretical wet coating thickness of 3 mils. The ePTFE membrane 1, which had been pre-restrained on a metal frame, was laminated to the coating while it was still wet, allowing the IEM solution to be absorbed into the pores. The composite was then dried at a temperature of 165°C in a convection oven with air inside. Upon drying, the IEM was fully absorbed into the microporous polymer structure (ePTFE membrane). The IEM also formed a layer between the bottom surface of the microporous polymer substrate and the polymer sheet substrate. During the second laydown, the same IEM with a solution composition of 38% water, 57.7% ethanol, 4.3% solids was coated onto the top surface of the composite (the surface opposite the polymer sheet substrate) using a drawdown bar with a theoretical wet coating thickness of 3 mils. The composite was then dried again at 165°C. At this point, the composite was nearly transparent, indicating that the microporous polymer structure was fully impregnated. The multilayer composite membrane was completely occluded, with a layer of IEM on both sides of the microporous polymer matrix. The resulting multilayer composite membrane had a thickness of 6.5 micrometers at 0% RH, 28% by volume occupied by the microporous polymer structure, and an acid content of 1.9 meq / cc.

[0247] This multi-layer composite membrane was then pressed between layers of woven PTFE material at 160° C. under 960 pounds per square inch pressure for 90 seconds to form the final membrane-protective layer composite.

[0248] The filaments are 200 denier expanded polytetrafluoroethylene (ePTFE) twisted at 32 twists per inch (TPI) in the Z direction. The filaments are available from WL Gore and Associates, Inc., Elkton, Maryland, as part number V112407. The filaments were woven into a plain weave scrim fabric on a Dornier Lepier loom using four harnesses, all equipped with leno healds. The scrim was produced using 15 lenopair ends per inch (ppi) in the warp direction (i.e., 30 monofilaments at epi) and 15 picks per inch (ppi) in the weft direction. No finishing or weaving processing aids were applied to the filaments or the woven fabric. The selvedge on both sides of the fabric was removed to produce the inventive samples.

[0249] Comparative Example 2

[0250] Mass per area is 2g / m 2An ePTFE membrane 1, 6.83 μm thick, 0.34 g / cc apparent density, and 86.2 psi bubble point, was pulled by hand to remove wrinkles and restrained in this state on a metal frame. A first laydown of PSFA solution (obtained from Asahi Glass Co., Ltd., Japan) with a solution composition of EV=379 cc / molar equivalent, 33.0% water, 52.2% ethanol, and 14.8% solids was then coated onto the top surface of the polymer sheet substrate. The polymer sheet substrate (obtained from Daicel Value Coating Co., Ltd., Japan) contained a protective layer of PET and cyclic olefin copolymer (COC) and was oriented with the COC side facing up. IEM (PFSA solution) coating was achieved using a Meyer bar with a theoretical wet coating thickness of 3 mils. The ePTFE membrane 1, previously restrained on a metal frame, was laminated to the coating while it was still wet, allowing the IEM solution to be absorbed into the pores. The composite was then dried at a temperature of 165°C in a convection oven with air inside. Upon drying, the IEM was fully absorbed into the microporous polymer structure (ePTFE membrane). The IEM also formed a layer between the bottom surface of the microporous polymer substrate and the polymer sheet substrate. During the second laydown, the same IEM was coated on the top surface of the composite (opposite surface from the polymer sheet substrate) with a solution composition of 38.0% water, 57.7% ethanol, 4.3% solids using a drawdown bar with a theoretical wet coating thickness of 1.5 mils. The composite was then dried again at 165°C. At this point the composite was nearly transparent, indicating that the microporous polymer structure was fully impregnated. The multilayer composite membrane was completely occluded, with a layer of IEM on both sides of the microporous polymer matrix. The resulting multilayer composite membrane had a thickness of 3.25 micrometers at 0% RH, 28% by volume occupied by the microporous polymer structure, and an acid content of 1.9 meq / cc. The multilayer composite membrane does not have a porous layer.

[0251] Example 2

[0252] Mass per area is 2g / m 2An ePTFE membrane 1, 6.83 μm thick, 0.34 g / cc apparent density, and 86.2 psi bubble point, was pulled by hand to remove wrinkles and restrained in this state on a metal frame. A first laydown of PSFA solution (obtained from Asahi Glass Co., Ltd., Japan) with a solution composition of EV=379 cc / molar equivalent, 33.0% water, 52.2% ethanol, and 14.8% solids was then coated onto the top surface of the polymer sheet substrate. The polymer sheet substrate (obtained from Daicel Value Coating Co., Ltd., Japan) contained a protective layer of PET and cyclic olefin copolymer (COC) and was oriented with the COC side facing up. IEM (PFSA solution) coating was achieved using a Meyer bar with a theoretical wet coating thickness of 3 mils. The ePTFE membrane 1, previously restrained on a metal frame, was laminated to the coating while it was still wet, allowing the IEM solution to be absorbed into the pores. The composite was then dried at a temperature of 165°C in a convection oven with air inside. Upon drying, the IEM was fully absorbed into the microporous polymer structure (ePTFE membrane). The IEM also formed a layer between the bottom surface of the microporous polymer substrate and the polymer sheet substrate. During the second laydown, the same IEM was coated on the top surface of the composite (opposite surface of the polymer sheet substrate) with a solution composition of 38.0% water, 57.7% ethanol, 4.3% solids using a drawdown bar with a theoretical wet coating thickness of 1.5 mils. The composite was then dried again at 165°C. At this point the composite was nearly transparent, indicating that the microporous polymer structure was fully impregnated. The multilayer composite membrane was completely occluded, with a layer of IEM on both sides of the microporous polymer matrix. The resulting multilayer composite membrane had a thickness of 3.25 micrometers at 0% RH, 28% by volume occupied by the microporous polymer structure, and an acid content of 1.9 meq / cc.

[0253] This multi-layer composite membrane was then pressed between layers of woven PTFE material at 160° C. under 960 pounds per square inch pressure for 90 seconds to form the final membrane-protective layer composite.

[0254] The filaments are 200 denier expanded polytetrafluoroethylene (ePTFE) twisted at 32 twists per inch (TPI) in the Z direction. The filaments are available from WL Gore and Associates, Inc., Elkton, Maryland, under part number V112407. The filaments were woven into a plain weave scrim fabric on a Dornier Lepier loom using four harnesses, all equipped with leno healds. The scrim was produced using 15 lenopair ends per inch (ppi) in the warp direction (i.e., 30 monofilaments at epi) and 15 picks per inch (ppi) in the weft direction. No finishing or weaving processing aids were applied to the filaments or woven fabric. The selvedge on both sides of the fabric was removed to produce the inventive samples.

[0255] Comparative Example 3

[0256] A laydown of PSFA solution (obtained from Asahi Glass Co., Ltd., Japan) with a solution composition of EV=379 cc / molar equivalent, 41% water, 53% ethanol, 6% solids was coated on the top side of the polymer sheet substrate. The polymer sheet substrate (obtained from Daicel Value Coating Co., Ltd., Japan) contained a protective layer of PET and cyclic olefin copolymer (COC) and was oriented with the COC side facing up. The IEM (PFSA solution) coating was achieved using a Mayer bar with a theoretical wet coating thickness of 7 mils. The cast film was subsequently dried at a temperature of 165° C. in a convection oven with air inside. The cast film is not a reinforced polymer electrolyte membrane since it does not contain a microporous polymer structure. The cast film also does not have a porous layer.

[0257] Comparative Example 4

[0258] A laydown of PSFA solution (obtained from Asahi Glass Co., Ltd., Japan) with a solution composition of EV=379 cc / molar equivalent, 41% water, 53% ethanol, 6% solids was coated onto the top side of a polymer sheet substrate. The polymer sheet substrate (obtained from Daicel Value Coating Co., Ltd., Japan) contained a protective layer of PET and cyclic olefin copolymer (COC) and was oriented with the COC side facing up. IEM (PFSA solution) coating was achieved using a Mayer bar with a theoretical wet coating thickness of 7 mils. The cast film was subsequently dried at a temperature of 165°C in a convection oven with air inside. The cast film is not a reinforced polymer electrolyte membrane as it does not contain a microporous polymer structure.

[0259] The cast film was then placed on the layer of woven PTFE, with the PSFA cast film in contact with the woven PTFE. The polymer sheet substrate, including the PET and protective layer, was then removed from the PFSA cast film. An additional layer of woven PTFE was then applied, such that the PSFA cast film was located between the two layers of woven PTFE. The multi-layer composite membrane was then pressed at 160° C. for 90 seconds under 960 pounds per square inch pressure to form the final membrane-protective layer composite.

[0260] The layer of woven PTFE material was derived from filaments of expanded polytetrafluoroethylene (ePTFE) having a fineness of 200 denier, twisted at 32 twists per inch (TPI) in the Z-direction. The filaments were available from WL Gore and Associates, Inc., Elkton, Maryland, under part number V112407. The filaments were woven into a plain weave scrim fabric on a Dornier Repier loom using four harnesses, all equipped with leno healds. The scrim was produced using 15 lenopair ends per inch (ppi) in the warp direction (i.e., 30 single filaments in epi) and 15 picks per inch (ppi) in the weft direction. No finishing or weaving processing aids were applied to the filaments or the woven fabric. The selvedge on both sides of the fabric was removed to create a comparison sample.

[0261] Properties of the example composite electrolyte membranes are shown in Table 1 and plotted in Figures 7 and 8. The improvement in short circuit pressure is shown in Figure 7, which shows a chart comparing the average short circuit pressure of comparable membranes to the average short circuit pressure of the composite electrolyte membranes of the invention. The improvement in burst pressure is shown in Figure 8, which shows a graph comparing the average burst pressure of comparable membranes to the average burst pressure of the composite electrolyte membranes of the invention.

[0262] From Table 1 and Figure 8, the average burst pressure of the 8 μm sample with the microporous polymer structure and two porous layers of the scrim (Example 1) is higher than the 8 μm sample with the microporous polymer structure and no porous layer in the reinforced polymer electrolyte membrane (Comparative Example 1) and the 8 μm sample with no microporous polymer structure and two porous layers of the scrim (Comparative Example 4). From Table 1 and Figure 8, a similar effect is seen for the average burst pressure, with Example 1 being stronger than the burst test limit (100 psi), while Comparative Examples 1 and 4 do not achieve a burst pressure higher than 30 psi. Both of these data sets show that the combination of the microporous polymer structure and the porous layer provides a synergistic performance effect, which is a surprising and original result. [Table 1]

[0263] From Table 1 and Figures 7 and 8, it can be seen that thinner membranes, such as the 4 μm reinforced polymer electrolyte membranes of Example 2 and Comparative Example 2, can benefit significantly by adding a porous layer of scrim for short circuit protection and additional strength in burst testing. Furthermore, for such thin film designs, the microporous polymer structure is a component of the polymer electrolyte membrane that is necessary to handle and process the ion exchange membrane into a composite electrolyte membrane with a porous layer. Without both the microporous polymer structure and the porous layer, the performance of these composite electrolyte membranes would be significantly reduced and the structure may become unfeasible.

[0264] Although the present invention has been described in detail, modifications within the spirit and scope of the present invention will be readily apparent to those skilled in the art. It is understood that the aspects of the present invention, parts of the various embodiments, and various features described above and / or in the appended claims can be combined or substituted in whole or in part. In the foregoing description of various embodiments, those embodiments that refer to other embodiments can be appropriately combined with other embodiments, as will be understood by those skilled in the art. Furthermore, those skilled in the art will appreciate that the foregoing description is merely illustrative and does not limit the present invention.

Claims

1. a) having a first surface, a second surface on the opposite side, a micro-porous polymer structure, and an ion exchange material, wherein the ion exchange material is at least partially embedded within the micro-porous polymer structure such that the micro-porous polymer structure is occlusive, at least one reinforced polymer electrolyte membrane, and b) a plurality of porous layers including at least a first porous layer and a second porous layer, A composite electrolyte membrane for an electrochemical device, comprising: The first porous layer has a first surface and a second surface on the opposite side such that the first surface of the first porous layer is adjacent to the first surface of the at least one reinforced polymer electrolyte membrane. The first porous layer has a plurality of pores having a pore size in the range of 5 μm to 5000 μm, and the plurality of pores provide one or more passages extending between the first surface and the second surface of the first porous layer, The second porous layer has a first surface and a second surface on the opposite side such that the first surface of the second porous layer is adjacent to the second surface of the at least one reinforced polymer electrolyte membrane. The second porous layer has a plurality of pores having a pore size in the range of 5 μm to 5000 μm, and the plurality of pores provide one or more passages extending through the second porous layer between the first surface and the second surface of the second porous layer. A composite electrolyte membrane for an electrochemical device.

2. The composite electrolyte membrane according to claim 1, wherein the micro-porous polymer structure is completely embedded with the ion exchange material.

3. The micro-porous polymer structure of the reinforced polymer electrolyte membrane has a first surface and a second surface on the opposite side, At least one layer of the ion exchange material is present on at least one of the first surface and the second surface of the micro-porous polymer structure. The composite electrolyte membrane according to claim 1.

4. The first layer of the ion exchange material is present on the first surface of the micro-porous polymer structure, and the second layer of the ion exchange material is present on the second surface of the micro-porous polymer structure. The composite electrolyte membrane according to claim 3.

5. One or more of the layers of the ion exchange material further comprises at least one membrane catalyst. The composite electrolyte membrane according to claim 3.

6. One or both of the first porous layer and the second porous layer are attached to the reinforced polymer electrolyte membrane. The composite electrolyte membrane according to claim 1.

7. A part of one or both of the first porous layer and the second porous layer is partially embedded in at least one layer of the ion exchange material. The composite electrolyte membrane according to claim 3.

8. The at least one reinforced polymer electrolyte membrane includes two or more micro-porous polymer structures. The composite electrolyte membrane according to claim 1.

9. At least one layer of the ion exchange material has a thickness of about 0.5 μm to about 20 μm at 0% RH. The composite electrolyte membrane according to claim 3.

10. The ion exchange material includes at least one ionomer. The composite electrolyte membrane according to claim 1.

11. The reinforced polymer electrolyte membrane has a thickness in the range of 4 μm to 30 μm. The composite electrolyte membrane according to claim 1.

12. Each of the porous layers of the plurality of porous layers can be independently selected from woven materials such as mesh, knitted material, paper, felt, mat or cloth and non-woven materials. The composite electrolyte membrane according to claim 1.

13. Each of the plurality of porous layers comprises a fluorinated polymer. The composite electrolyte membrane according to claim 1.

14. The composite electrolyte membrane according to claim 1, wherein the porous layer among the plurality of porous layers contains glass fibers.

15. The composite electrolyte membrane according to claim 1, wherein the porous layer among the plurality of porous layers contains a ceramic material.

16. The composite electrolyte membrane according to claim 1, wherein each of the plurality of porous layers is non-conductive.

17. The composite electrolyte membrane according to claim 1, wherein the composite electrolyte membrane has a monolithic structure.

18. A membrane electrode assembly for an electrochemical device, comprising: At least one electrode including a first electrode, and The composite electrolyte membrane according to any one of claims 1 to 17, wherein the composite electrolyte membrane is adjacent to the at least one electrode such that the first porous layer is between the first electrode and the at least one reinforced polymer electrolyte membrane. A membrane electrode assembly for an electrochemical device, comprising the above.

19. The membrane electrode assembly according to claim 18, wherein the at least one electrode includes an electrode catalyst layer containing at least one electrode catalyst.

20. An electrolysis device comprising the composite electrolyte membrane according to any one of claims 1 to 17.

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