Composite electrolyte membrane

Abstract

To provide an electrolyte membrane having a small dimensional change in hydration, that is, a low swelling property, in particular, a low swelling property in a machine direction and a transverse direction of the membrane.SOLUTION: A composite electrolyte membrane comprises: a) at least one porous layer comprising a microporous polymer structure; and b) an ion exchange material at least partially embedded within the microporous polymer structure to render the microporous polymer structure occlusive. The composite electrolyte membrane has a modulus of elasticity in a first axial direction and a modulus of elasticity in a second axial direction of the composite electrolyte membrane of at least about 450 MPa at 50% relative humidity. The at least one porous layer has an elastic strength in the first axial direction and an elastic strength in the second axial direction of the porous layer of at least about 30 N / m when measured according to a specific tensile strength test. An absolute ratio of the elastic modulus of the composite electrolyte membrane in the first axial direction of the composite electrolyte membrane to the elastic modulus of the composite electrolyte membrane in the second axial direction of the composite electrolyte membrane is about 0.45 to about 2.20.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] Field The present disclosure relates to improved composite electrolyte membranes with low swelling properties, membrane electrode assemblies and electrochemical devices including said membranes, and methods for making said membranes. [Background technology]

[0002] background A redox flow battery contains two half-cells, each containing a liquid electrolyte reservoir (catholyte and anolyte) separated by an electrolyte membrane, which acts as a physical and electrical separator, preventing crossover of active species between the half-cells while allowing the transfer of protons between the electrolyte reservoirs to balance the charge.

[0003] The electrolyte membrane (e.g., a composite polymer electrolyte membrane) used in a redox flow battery is typically sandwiched between two electrodes (a cathode and an anode), with each electrode compressed against opposite surfaces of the electrolyte membrane. The electrolyte membrane and electrodes are usually sandwiched between two bipolar plates and held together by a frame to create a redox flow battery cell. Redox flow battery systems often include a stack of redox flow battery cells connected in series.

[0004] The electrolyte membrane must be easily integrated into the cell stack. Generally, two methods are used to assemble the electrolyte membrane in a redox flow battery cell stack: wet assembly and dry assembly.

[0005] In the wet assembly approach, the electrolyte membrane is pre-wetted with water to swell the membrane before the electrodes are compressed against it, and the complete system is held together by a frame. In the dry assembly approach, all elements of the battery cell are assembled dry, and the membrane comes into contact with the solvent of the electrolyte solution once the cell is assembled.

[0006] Upon contact with a liquid electrolyte, the electrolyte membrane takes up at least some liquid (usually water) from the electrolyte solution, causing the membrane to swell. This swelling can alter the membrane's properties during operation compared to initial measurements performed on the membrane in its dry state. For example, upon contact with the electrolyte, the membrane absorbs some liquid and often swells, resulting in a change in membrane dimensions. This can cause the membrane to sag, potentially reducing its performance during operation. Furthermore, this change in dimensions upon swelling can damage the membrane by wrinkling, folding, or pressing against other cell components.

[0007] The advantage of the dry assembly approach is that it requires fewer steps than the wet assembly approach, thus improving assembly efficiency and minimizing manufacturing costs. However, state-of-the-art membranes assembled using the dry approach undergo dimensional changes when they come into contact with electrolyte fluid and swell, which can cause damage to the membrane. In contrast, membranes assembled using the wet approach tend to undergo less dimensional change between assembly into the cell and battery operation, thereby reducing the risk of damaging the electrolyte membrane after assembly in the cell.

[0008] Furthermore, electrolyte membranes, which swell significantly upon contact with the electrolyte solution, tend to increase in volume, which in turn increases the area of ​​the cell's separator. Increasing the area at the cell's ion crossover point is problematic because it can cause a decrease in ion shielding and current efficiency voltage. The absolute flux of ions across the membrane is proportional to the membrane's area. Increasing the electrolyte membrane's area can decrease ion shielding efficiency (i.e., more ions can pass through the membrane to the other half-cell). This can negatively impact the battery's life and efficiency. A decrease in the battery's current efficiency means that more energy is required to charge the battery compared to the energy output available from it.

[0009] Therefore, there is a need for an electrolyte membrane that has low dimensional change upon hydration, i.e., low swelling properties, especially in the machine and cross directions of the membrane, which provides good battery efficiency and does not exhibit blistering upon assembly of the electrolyte membrane in a battery cell. Summary of the Invention

[0010] Abstract In one embodiment, a composite electrolyte membrane, the composite electrolyte membrane comprising: a) at least one porous layer comprising a microporous polymer structure; and b) an ion exchange material at least partially embedded within said microporous polymer structure, rendering said microporous polymer structure occlusive; Including, c) the composite electrolyte membrane has an elastic modulus of greater than about 450 MPa at 50% relative humidity in a first axial direction and a second axial direction of the composite electrolyte membrane; d) the at least one porous layer has a resilient strength of at least about 30 N / m in a first axis direction and a second axis direction of the porous layer when measured according to the Tensile Strength Test described herein; A composite electrolyte membrane is provided, wherein the absolute ratio of the elastic strength of said at least one porous layer in the first axial direction and the second axial direction of said porous layer is from about 0.45 to about 2.20.

[0011] In another aspect, a composite electrolyte membrane, the composite electrolyte membrane comprising: a) at least one porous layer comprising a microporous polymer structure; and b) an ion exchange material at least partially embedded within said microporous polymer structure, rendering said microporous polymer structure occlusive; Including, the composite electrolyte membrane has an elastic modulus of at least about 300 MPa at about 100% relative humidity in a first axial direction of the composite electrolyte membrane, and an elastic modulus of at least about 300 MPa at about 100% relative humidity in a second axial direction of the composite electrolyte membrane, when measured according to the Tensile Strength Test described herein; the at least one porous layer has an elastic strength of at least about 30 N / m in a first direction and a second direction of the composite electrolyte membrane when measured according to the Tensile Strength Test described herein; and A composite electrolyte membrane is provided, wherein the absolute ratio of the elastic strength of the at least one porous layer in the first axial direction and the second axial direction of the porous layer is from about 0.40 to about 2.20.

[0012] In another aspect, a composite electrolyte membrane, the composite electrolyte membrane comprising: a) at least one porous layer comprising a microporous polymer structure; and b) an ion exchange material at least partially embedded within said microporous polymer structure, rendering said microporous polymer structure occlusive; Including, the composite electrolyte membrane has an elastic modulus in a first axis direction and an elastic modulus in a second axis direction of at least about 450 MPa at 50% relative humidity when measured according to the Tensile Strength Test described herein; the at least one porous layer has an elastic strength in a first axis direction and an elastic strength in a second axis direction of the porous layer of at least about 30 N / m when measured according to the Tensile Strength Test described herein; There is provided a composite electrolyte membrane, in which the absolute ratio of the elastic modulus of the composite electrolyte membrane in a first axial direction to the elastic modulus of the composite electrolyte membrane in a second axial direction of the composite electrolyte membrane is about 0.45 to about 2.20.

[0013] In another aspect, a composite electrolyte membrane, the composite electrolyte membrane comprising: a) at least one porous layer comprising a microporous polymer structure; and b) an ion exchange material at least partially embedded within said microporous polymer structure, rendering said microporous polymer structure occlusive; Including, the composite electrolyte membrane has a modulus of elasticity in the first and second axes of the composite electrolyte membrane of at least about 300 MPa at about 100% relative humidity when measured according to the Tensile Strength Test described herein; the at least one porous layer has a resilient strength of at least about 30 N / m in a first axis direction and a second axis direction of the porous layer when measured according to the Tensile Strength Test described herein; and There is provided a composite electrolyte membrane, wherein the absolute ratio of the elastic modulus of the composite electrolyte membrane in the first axial direction to the elastic modulus of the composite electrolyte membrane in the second axial direction is about 0.45 to about 2.20.

[0014] In another aspect, a composite electrolyte membrane, the composite electrolyte membrane comprising: a) at least one porous layer comprising a microporous polymer structure; and b) an ion exchange material at least partially embedded within said microporous polymer structure, rendering said microporous polymer structure occlusive; Including, The composite electrolyte membrane has an elastic modulus in a first axis direction and an elastic modulus in a second axis direction of at least about 300 MPa at about 100% relative humidity when measured according to the tensile strength test described herein.

[0015] The absolute ratio of the elastic modulus of the composite electrolyte membrane in the first axial direction to the second axial direction can be about 0.40 to about 2.20, or about 0.45 to about 2.20, or about 0.45 to about 2.10, or about 0.80 to about 1.20, or about 0.80 to about 1.00, or about 0.80 to about 0.90, or about 0.70 to about 1.30, or about 0.60 to about 1.80, or about 0.90 to about 1.20, or about 1.00 to about 1.20, or about 1.10 to about 1.20.

[0016] For the avoidance of doubt, the properties of the at least one porous layer comprising a polymer that comprises a microporous polymer structure refer to the properties of the porous layer itself before it is treated or laminated with a composite electrolyte membrane. That is, the properties of the at least one porous layer are measured on the at least one porous layer in its original state (i.e., untreated or without an ion exchange material embedded therein). The properties of a composite electrolyte membrane refer to the properties measured on the completed laminate that includes at least one porous layer comprising a microporous polymer structure and an ion exchange material at least partially embedded within said microporous polymer structure, rendering said microporous polymer structure occlusive.

[0017] In the context of the present disclosure, a first axial direction (e.g., machine direction, MD) of the composite electrolyte membrane is aligned with a first axial direction of the porous layer, and a second axial direction (e.g., transverse direction, TD) of the composite electrolyte membrane is aligned with a second axial direction of the porous layer.

[0018] The absolute ratio of the elastic strength of at least one porous layer in the first axial direction to the second axial direction of the porous layer can be about 0.40 to about 2.20, or about 0.45 to about 2.10, or about 0.80 to about 1.20, or about 0.80 to about 1.00, or about 0.80 to about 0.90, or about 0.70 to about 1.30, or about 0.60 to about 1.80, or about 0.90 to about 1.20, or about 1.00 to about 1.20, or about 1.10 to about 1.20.

[0019] The composite electrolyte membrane may have an ultimate tensile strength of at least about 55 MPa in a first axial direction of the composite electrolyte membrane when measured according to the Tensile Strength Test described herein at 50% relative humidity and 25° C. The composite electrolyte membrane may have an ultimate tensile strength of about 55 MPa to about 90 MPa, or about 55 MPa to about 80 MPa, or 55 MPa to about 70 MPa, or about 55 MPa to about 60 MPa, or about 60 MPa to about 90 MPa, or about 60 MPa to about 80 MPa, or about 80 MPa to about 70 MPa in a first axial direction of the composite electrolyte membrane when measured according to the Tensile Strength Test described herein at 50% relative humidity and 25° C. The composite electrolyte membrane may have an ultimate tensile strength in a first axis direction of the composite electrolyte membrane of about 55 MPa, or about 58 MPa, or about 59 MPa, or about 60 MPa, or about 61 MPa, or about 62 MPa, or about 65 MPa when measured according to the Tensile Strength Test described herein at 50% relative humidity and 25°C.

[0020] The composite electrolyte membrane may have an ultimate tensile strength of at least about 60 MPa in a second axial direction of the composite electrolyte membrane when measured according to the Tensile Strength Test described herein at 50% relative humidity and 25° C. The composite electrolyte membrane may have an ultimate tensile strength of about 60 MPa to about 120 MPa, or about 60 MPa to about 100 MPa, or 60 MPa to about 80 MPa, or about 60 MPa to about 70 MPa, or about 65 MPa to about 90 MPa, or about 70 MPa to about 100 MPa, or about 80 MPa to about 120 MPa in a second axial direction of the composite electrolyte membrane when measured according to the Tensile Strength Test described herein at 50% relative humidity and 25° C. The composite electrolyte membrane may have an ultimate tensile strength of about 60 MPa, or about 62 MPa, or about 64 MPa, or about 65 MPa, or about 66 MPa, or about 68 MPa, or about 70 MPa in the second axis direction of the composite electrolyte membrane, when measured according to the Tensile Strength Test described herein at 50% relative humidity and 25°C.

[0021] In the context of the present disclosure, the total porous layer ultimate web tensile strength can be the sum of the ultimate tensile strengths of all porous layers present in the composite electrolyte membrane. In embodiments where there is only one porous layer, the total porous layer ultimate web tensile strength corresponds to the ultimate tensile strength of a single porous layer present in the membrane. In embodiments where there is more than one porous layer present in the composite electrolyte membrane, the total porous layer ultimate web tensile strength can be the sum of the ultimate web tensile strengths of all porous layers present in the composite electrolyte membrane.

[0022] The total porous layer ultimate web tensile strength in the first axial direction of the porous layers, when measured according to the Tensile Strength Test described herein, can be at least about 800 N / m. The total porous layer ultimate web tensile strength in the first axial direction of the porous layers, when measured according to the Tensile Strength Test described herein, can be from about 800 N / m to about 2000 N / m, or from about 1000 N / m to about 2000 N / m, from about 1500 N / m to about 2000 N / m, from about 1200 N / m to about 1500 N / m, or from about 1500 N / m to about 2000 N / m. The total porous layer ultimate web tensile strength in the first axial direction of the porous layer when measured according to the Tensile Strength Test described herein can be about 1000 N / m, or about 1200 N / m, or about 1300 N / m, or about 1400 N / m, or about 1500 N / m, or about 1600 N / m, or about 1800 N / m, or about 2000 N / m.

[0023] The total porous layer ultimate tensile strength in the second axial direction of the porous layer can be at least about 800 N / m when measured according to the Tensile Strength Test described herein. The total porous layer ultimate tensile strength in the second axial direction of the porous layer when measured according to the Tensile Strength Test described herein can be from about 800 N / m to about 3000 N / m, or from 1000 N / m to about 3000 N / m, or from about 1200 N / m to about 3000 N / m, or from about 1500 N / m to about 3000 N / m, or from about 1100 N / m to about 1500 N / m, or from about 1500 N / m to about 2000 N / m, or from about 1500 N / m to about 3000 N / m, or from about 2000 N / m to about 3000 N / m, or from about 2000 N / m to about 2500 N / m, or from about 2500 N / m to about 3000 N / m. The total porous layer ultimate tensile strength in the second axial direction of the porous layer when measured according to the Tensile Strength Test described herein can be about 800 N / m, or about 900 N / m, or about 1000 N / m, or about 1100 N / m, or about 1200 N / m, or about 1300 N / m, or about 1400 N / m, or about 1500 N / m, or about 2000 N / m, or about 2500 N / m, or about 3000 N / m.

[0024] In the context of the present disclosure, the total porous layer elastic strength can be the sum of the elastic strengths of all porous layers present in the composite electrolyte membrane. In embodiments where there is only one porous layer, the total porous layer elastic strength corresponds to the elastic strength of a single porous layer present in the membrane. In embodiments where there is more than one porous layer present in the composite electrolyte membrane, the total porous layer elastic strength can be the sum of the elastic strengths of all porous layers present in the composite electrolyte membrane.

[0025] The total porous layer elastic strength in the first axial direction of the porous layer, as measured according to the Tensile Strength Test described herein, can be at least about 30 N / m. The total porous layer elastic strength in the first axial direction of the porous layer, as measured according to the Tensile Strength Test described herein, can be about 30 N / m to about 400 N / m, or about 40 N / m to about 300 N / m, or about 45 N / m to about 250 N / m, or about 40 N / m to about 80 N / m, or about 80 N / m to about 250 N / m. The total porous layer elastic strength in the first axial direction of the porous layer, as measured according to the Tensile Strength Test described herein, can be about 40 N / m, or about 60 N / m, or about 80 N / m, or about 100 N / m, or about 150 N / m, or about 200 N / m, or about 250 N / m, or about 300 N / m.

[0026] The total porous layer elastic strength in the second axial direction of the porous layer, as measured according to the Tensile Strength Test described herein, can be at least about 30 N / m. The total porous layer elastic strength in the first axial direction of the porous layer, as measured according to the Tensile Strength Test described herein, can be about 30 N / m to about 400 N / m, or about 40 N / m to about 300 N / m, or about 45 N / m to about 250 N / m, or about 40 N / m to about 80 N / m, or about 80 N / m to about 250 N / m. The total porous layer elastic strength in the first axial direction of the porous layer, as measured according to the Tensile Strength Test described herein, can be about 40 N / m, or about 60 N / m, or about 80 N / m, or about 100 N / m, or about 150 N / m, or about 200 N / m, or about 250 N / m, or about 300 N / m.

[0027] The composite electrolyte membrane swelling ratio in the first direction can be about 8% or less, or about 7% or less, or about 6% or less, or about 5% or less, when measured by the swelling test described herein at about 100% relative humidity and about 100° C. The composite electrolyte membrane swelling ratio in the first direction can be about 0.1% to about 8%, or about 1% to about 8%, or about 2% to about 8%, or about 3% to about 8%, or about 5% to about 8%, or about 7% to about 8%, or about 0.1% to about 5%, or about 1% to about 4%, or about 0.1% to about 3.5%, or about 1% to about 3%, when measured by the swelling test described herein at 100% relative humidity and about 100° C. The composite electrolyte membrane swelling ratio in the first direction can be about 1%, or about 2%, or about 3%, or about 4%, or about 5%, or about 5.2%, or about 6%, or about 7%, or about 8%, when measured using the Swelling Test described herein at 100% relative humidity and about 100°C.

[0028] The swelling ratio of the composite electrolyte membrane in the second direction, when measured by the swelling test described herein at about 100°C and 100% relative humidity, can be about 8% or less, or 7% or less, or about 6% or less, or about 5% or less. The swelling ratio of the composite electrolyte membrane in the second direction, when measured by the swelling test described herein at about 100°C and 100% relative humidity, can be about 0.1% to about 8%, or about 1% to about 8%, or about 2% to about 8%, or about 3% to about 8%, or about 5% to about 8%, or about 7% to about 8%, or about 0.1% to about 5%, or about 1% to about 4%, or about 0.1% to about 3.5%, or about 1% to about 3%. The swelling ratio of the composite electrolyte membrane in the second direction can be about 1%, or about 2%, or about 3%, or about 4%, or about 5%, or about 6%, or about 7%, or about 8%, as measured in the swelling test described herein at about 100°C and 100% relative humidity.

[0029] A composite electrolyte membrane can include a single porous layer. A composite electrolyte membrane can include two or more porous layers. In embodiments in which the composite electrolyte membrane includes at least two porous layers, the compositions of the at least two porous layers can be the same or different.

[0030] The microporous polymer structure of the porous layer may comprise a fluorinated polymer. The fluorinated polymer may be selected from the group consisting of 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. The fluorinated polymer may be perfluorinated expanded polytetrafluoroethylene (ePTFE).

[0031] In the context of the present disclosure, the total content of microporous polymer structures in a composite membrane is the total mass of microporous polymer structures in the composite membrane per total area of ​​the composite membrane (g / m 2 ). A composite membrane can include more than one type of microporous polymer structure. For example, a composite membrane can include a single type of microporous polymer structure (e.g., ePTFE) present in at least two reinforcement layers. A composite membrane can include at least two reinforcement layers, each of which can include a mixture of different types of microporous polymer structures (e.g., a fluorinated polymer and a hydrocarbon polymer). A composite membrane can include at least two reinforcement layers, a first of which can include a single type of microporous polymer structure (e.g., ePTFE) and a second of which can include a single type of microporous polymer structure (e.g., a hydrocarbon polymer) that is different from the microporous polymer structure of the first of the at least two reinforcement layers.

[0032] In embodiments in which the microporous polymer structure of the porous layer comprises ePTFE, the composite electrolyte membrane has a mass of at least about 5.5 g m -2In an embodiment in which the microporous polymer structure of the porous layer comprises ePTFE, the composite electrolyte membrane can have a total content (mass per unit area) of about 5.5 g m based on the total area (mass per unit area) of the composite electrolyte membrane. -2 ~Approx. 80g m -2 , or approximately 8 g m -2 ~Approx. 70g m -2 , or approximately 8 g m -2 ~Approx. 60g m -2 , or approximately 8 g m -2 ~Approx. 50g m -2 , or approximately 8 g m -2 ~Approx. 50g m -2 , or approximately 8 g m -2 ~Approx. 40g m -2 , or approximately 8 g m -2 ~Approx. 30g m -2 , or approximately 8 g m -2 ~Approx. 20g m -2 , or approximately 8 g m -2 ~Approx. 15g m -2 , or approximately 8 g m -2 ~Approx. 10g m -2 , or approximately 10 g m -2 ~Approx. 80g m -2 , or approximately 10 g m -2 ~Approx. 70g m -2 , or approximately 10g·m -2 ~Approx. 60g m -2 , or approximately 10 g m -2 ~Approx. 50g m -2 , or approximately 10 g m -2 ~Approx. 40g m -2 , or approximately 10 g m -2 ~Approx. 30g m -2 , or approximately 10 g m -2 ~Approx. 20g m -2 , or approximately 10 g m -2 ~Approx. 15g m -2 , or approximately 20 g m -2 ~Approx. 80g m -2 , or approximately 20 g m -2 ~Approx. 70g m -2 , or approximately 20 g m -2 ~Approx. 60g m -2 , or approximately 20 g m -2~Approx. 50g m -2 , or approximately 20 g m -2 ~Approx. 40g m -2 , or approximately 30 g m -2 ~Approx. 80g m -2 , or approximately 30 g m -2 ~Approx. 70g m -2 , or approximately 30 g m -2 ~Approx. 60g m -2 , or approximately 30 g m -2 ~Approx. 50g m -2 , or approximately 30 g m -2 ~Approx. 40g m -2 , or approximately 30 g m -2 ~Approx. 35g m -2 , or approximately 40 g·m -2 ~Approx. 50g m -2 The composite electrolyte membrane can have a total content (mass per unit area) of the microporous polymer structure of about 8 g m based on the total area of ​​the composite electrolyte membrane. -2 , or approximately 10 g m -2 , or approximately 12 g m -2 , or approximately 15 g m -2 , about 18g m -2 , or approximately 21 g·m -2 , or approximately 24 g·m -2 , or approximately 26 g·m -2 , or approximately 28g·m -2 , or approximately 29 g·m -2 , or approximately 30 g m -2 , or approximately 31 g·m -2 , or approximately 32 g·m -2 , or approximately 34 g m -2 , or approximately 35 g·m -2 , or 40g·m -2 , or approximately 50 g·m -2 , or approximately 60 g·m -2 , or approximately 70 g·m -2 , or approximately 80 g·m -2 The total content of the microporous polymer structure may be

[0033] The microporous polymer structure of the porous layer may comprise a hydrocarbon polymer, which may include polyethylene, polypropylene, polycarbonate, polystyrene, or mixtures thereof.

[0034] The composite electrolyte membrane can have a total content of microporous polymer structures of about 15% by volume to about 70% by volume, or about 20% by volume to about 50% by volume, or about 35% by volume to about 70% by volume, or about 35% by volume to about 50% by volume, or about 35% by volume to about 45% by volume, or about 40% by volume to about 45% by volume, or about 40% by volume to about 50% by volume, based on the total volume of the composite electrolyte membrane. The composite electrolyte membrane can have a total content of microporous polymer structures of about 20% by volume, or about 36% by volume, or about 38% by volume, or about 40% by volume, or about 42% by volume, or about 44% by volume, or about 46% by volume, or about 48% by volume, or about 50% by volume, based on the total volume of the composite electrolyte membrane.

[0035] The composite electrolyte membrane has a thickness of about 10 μm to about 115 μm, or about 10 μm to about 100 μm, or about 10 μm to about 90 μm, or about 10 μm to about 80 μm, or about 10 μm to about 75 μm, or about 10 μm to about 70 μm, or about 10 μm to about 60 μm, or about 10 μm to about 50 μm, or about 10 μm to about 40 μm, or about 10 μm to about 30 μm, when measured at 25° C. and 50% relative humidity in the thickness measurement test described herein. The thickness may be about 0 μm, or about 10 μm to about 20 μm, or about 10 μm to about 15 μm, or about 10 μm to about 12 μm, or about 20 μm to about 60 μm, or about 30 μm to about 60 μm, or about 40 μm to about 60 μm, or about 12 μm to about 30 μm, or about 12 μm to about 20 μm, or about 15 μm to about 30 μm, or about 15 μm to about 20 μm, about 20 μm to about 30 μm, or about 15 μm to about 90 μm. The composite film has a thickness of about 10 μm, or about 11 μm, or about 12, or about 13 μm, or about 14 μm, or 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 26 μm, when measured at 25° C. and 50% relative humidity in the Thickness Measurement Test described herein. It can have a thickness of 5 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, or about 80 μm, or about 85 μm, or about 90 μm, or about 95 μm, or about 100 μm, or about 105 μm, or about 110 μm, or about 115 μm.

[0036] The at least one porous layer can have a thickness of at least about 0.1 μm when measured at 25° C. at 50% relative humidity in the Thickness Measurement Test described herein. The at least one porous layer can have a thickness of from about 0.1 μm to about 230 μm, or from about 12 μm to about 230 μm, or from about 20 μm to about 230 μm, or from about 40 μm to about 230 μm, when measured at 25° C. at 50% relative humidity in the Thickness Measurement Test described herein. It can have a thickness of about 60 μm to about 230 μm, or about 80 μm to about 230 μm, or about 100 μm to about 230 μm, or about 120 μm to about 230 μm, or about 140 μm to about 230 μm, or about 160 μm to about 230 μm, or about 180 μm to about 230 μm, or about 200 μm to about 230 μm, or about 210 μm to about 230 μm, or about 220 μm to about 230 μm, or about 12 μm to about 200 μm, or about 12 μm to about 150 μm, or about 12 μm to about 100 μm, or about 12 μm to about 50 μm, or about 14 μm to about 90 μm. The at least one porous layer can have a thickness of about 14 μm, or about 20 μm, or about 25 μm, or about 50 μm, or about 55 μm, or about 60 μm, or about 70 μm, or about 75 μm, or about 80 μm, or about 85 μm, or about 90 μm, or about 120 μm, or about 150 μm, or about 200 μm, or about 230 μm, when measured at 25° C. at 50% relative humidity in the Thickness Measurement Test described herein.

[0037] The at least one porous layer can have a first surface and a second surface. The ion exchange material can be layered on at least one of the first surface and / or second surface of the at least one porous layer. The ion exchange material can be layered on both the first surface and the second surface of the at least one porous layer. In embodiments in which the ion exchange material is layered on both the first surface and the second surface of the at least one porous layer, the ion exchange material of the layer of ion exchange material formed on the first surface of the at least one porous layer can be different from the ion exchange material of the layer of ion exchange material formed on the second surface of the at least one porous layer. Alternatively, in embodiments in which the ion exchange material is layered on both the first surface and the second surface of the at least one porous layer, the ion exchange material of the layer of ion exchange material formed on the first surface of the at least one porous layer can be the same as the ion exchange material of the layer of ion exchange material formed on the second surface of the at least one porous layer. Alternatively, in embodiments in which the ion exchange material is layered on only the first surface or the second surface of the at least one porous layer comprising a microporous polymer structure, the other first surface or second surface of the at least one porous layer is non-occlusive.

[0038] The ion exchange material can include at least one ionomer. The ion exchange material can include at least two ionomers. The at least one ionomer can include a proton-conducting polymer. The proton-conducting material can be perfluorinated or hydrocarbon-based. Suitable hydrocarbon proton-conducting materials include, for example, 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, and polyethylene oxide. Suitable perfluorinated proton-conducting polymers can include perfluorosulfonic acid polymers, perfluorocarboxylic acid polymers, and perfluorophosphonic acid polymers. The at least one ionomer can have a density of about 1.9 g / cc or greater at 25°C and 0% relative humidity. The at least one ionomer can have a SO3 content of about 500 g / eq. - ~ Approximately 2000g / eq SO3 - , or approximately 500 g / eq SO3 - ~Approximately 1000g / eq SO3 - , or approximately 500 g / eq SO3 - ~Approximately 800g / eq SO3 - , or approximately 700 g / eq SO3 - ~Approximately 1500g / eq SO3 - , or approximately 1000 g / eq SO3 - ~ Approximately 2000g / eq SO3 - , or approximately 1500 g / eq SO3 - ~ Approximately 2000g / eq SO3 - The ion exchange material can have a total equivalent weight (EW) of about 500 g / eq of SO3 - , or approximately 600 g / eq SO3 - , or approximately 700 g / eq SO3 - , or approximately 800 g / eq SO3 - , or approximately 850 g / eq SO3 - , or approximately 900 g / eq SO3 - , or approximately 1000 g / eq SO3- , or approximately 1200 g / eq SO3 - , or approximately 1400 g / eq SO3 - , or approximately 1600 g / eq SO3 - , or approximately 1800 g / eq SO3 - It can have an equivalent of

[0039] The composite electrolyte membrane may have an elastic modulus of about 300 MPa to about 2000 MPa, or about 300 MPa to about 600 MPa, or about 300 MPa to about 1500 MPa, or about 300 MPa to about 1000 MPa, or about 600 MPa to about 1500 MPa, or about 600 MPa to about 1000 MPa, or about 600 MPa to about 800 MPa, or about 800 MPa to about 900 MPa, or about 700 MPa to about 800 MPa, or about 1000 MPa to about 2000 MPa, or about 1500 MPa to about 2000 MPa, at about 100% relative humidity (e.g., 95% relative humidity). The elastic modulus is determined based on tensile strength measurements using the tensile strength test described herein.

[0040] The composite electrolyte membrane may have an elastic modulus of about 300 MPa to about 2000 MPa, or about 300 MPa to about 600 MPa, or about 300 MPa to about 1500 MPa, or about 300 MPa to about 1000 MPa, or about 600 MPa to about 1500 MPa, or about 600 MPa to about 1000 MPa, or about 600 MPa to about 800 MPa, or about 800 MPa to about 900 MPa, or about 1000 MPa to about 2000 MPa, or about 1500 MPa to about 2000 MPa, at about 100% relative humidity (e.g., 95% relative humidity). The elastic modulus is determined based on tensile strength measurements using the tensile strength test described herein.

[0041] The composite electrolyte membrane may have a modulus of elasticity at 50% relative humidity in a first axial direction of the composite electrolyte membrane of about 450 MPa to about 2300 MPa, or about 300 MPa to about 600 MPa, or about 300 MPa to about 1500 MPa, or about 300 MPa to about 1000 MPa, or about 600 MPa to about 1500 MPa, or about 600 MPa to about 1000 MPa, or about 600 MPa to about 800 MPa, or about 800 MPa to about 900 MPa, or about 700 MPa to about 800 MPa, or about 1000 MPa to about 2000 MPa, or about 1500 MPa to about 2000 MPa, or about 2000 MPa to about 2300 MPa. The modulus of elasticity is determined based on tensile strength measurements using the tensile strength test described herein.

[0042] The composite electrolyte membrane may have an elastic modulus at 50% relative humidity in the second axial direction of the composite electrolyte membrane of about 450 MPa to about 2300 MPa, or about 300 MPa to about 600 MPa, or about 300 MPa to about 1500 MPa, or about 300 MPa to about 1000 MPa, or about 600 MPa to about 1500 MPa, or about 600 MPa to about 1000 MPa, or about 600 MPa to about 800 MPa, or about 800 MPa to about 900 MPa, or about 700 MPa to about 800 MPa, or about 1000 MPa to about 2000 MPa, or about 1500 MPa to about 2000 MPa, or about 2000 MPa to about 2300 MPa. The elastic modulus is determined based on tensile strength measurements using the tensile strength test described herein.

[0043] The composite electrolyte membrane can swell preferentially in the third axial direction of the composite electrolyte membrane. The composite electrolyte membrane can have a swelling degree of about 5% to about 150%, or about 5% to about 100%, or about 10% to about 100%, or about 10% to about 90%, or about 10% to about 80%, or about 20% to about 80%, or about 50% to about 80%, or about 30% to about 50%, or about 40% to about 80%, or about 30% to about 90%, or about 50% to about 80%, or about 50% to about 90%, when measured at about 100% relative humidity (e.g., 95% RH) and 100°C according to the swelling test described herein.

[0044] The composite electrolyte membrane may further include at least one support layer attached to one or more outer surfaces of the composite electrolyte membrane.

[0045] The composite electrolyte membrane can be a redox flow battery composite electrolyte membrane. The composite electrolyte membrane can be a fuel cell composite electrolyte membrane. The composite electrolyte membrane can be an electrolyzer composite electrolyte membrane.

[0046] In another embodiment, there is provided a composite electrolyte membrane-electrode assembly for an electrochemical device, comprising: a) at least one electrode; and b) a composite electrolyte membrane as described herein in contact with said at least one electrode; A composite electrolyte membrane-electrode assembly is provided, comprising:

[0047] The composite electrolyte membrane can be attached to at least one electrode. The composite electrolyte membrane can have a first surface and a second surface, and the electrode can be a first electrode layer attached to the first surface of the composite electrolyte membrane. The membrane electrode assembly can further include a second electrode layer attached to the second surface of the composite electrolyte membrane.

[0048] The electrode, or one or both of the first and second electrode layers, can be a porous layer. The electrode, or one or both of the first and second electrode layers can be selected from felt, paper, or woven materials.

[0049] At least one electrode can include carbon fibers. At least one electrode can include doped carbon fibers. The carbon fibers can have a diameter of about 5 to about 30 μm.

[0050] At least one electrode may be selected from Pt / Co / Pd / doped graphene / MoSx (cathode), RuO2 / IrO2 / Ir and Ru bimetallic oxides, Ir / Pt bimetallic oxides, mixtures of Ti, Sn, Ta, Nb, Sb, Pb, Mn oxides with Ir or Ru oxides.

[0051] The electrodes can include a catalyst support selected from carbon (eg, carbon black / CNT) or carbon nanoparticles doped with N, P, S, or B.

[0052] The composite electrolyte membrane-electrode assembly is a) at least one electrode; and b) a composite electrolyte membrane as described herein; wherein the at least one electrode is in contact with the composite electrolyte membrane.

[0053] The composite electrolyte membrane-electrode assembly is a) at least one electrode; and b) a composite electrolyte membrane as described herein; wherein the at least one electrode is in contact with the composite electrolyte membrane.

[0054] The composite electrolyte membrane-electrode assembly may further include a fluid (i.e., gas or liquid) diffusion layer, which may be selected from felt, paper or woven materials, carbon / carbon-based diffusion layers, titanium porous sintered powder mesh / plate / fiber / felt, stainless steel mesh, or mixtures thereof.

[0055] The electrolyzer composite electrolyte membrane-electrode assembly can include a first electrode and a second electrode. The first electrode can form the anode and the second electrode can form the cathode.

[0056] The electrolytic cell composite electrolyte membrane-electrode assembly is a first electrode layer and a second electrode layer; a composite electrolyte membrane as described herein; wherein the first electrode layer and the second electrode layer are disposed on opposite sides of the composite electrolyte membrane, and a fluid diffusion layer disposed on the first electrode layer and the second electrode layer; may include:

[0057] The first electrode layer and the second electrode layer can be a first electrode catalyst layer and a second electrode catalyst layer. The first electrode catalyst layer and the second electrode catalyst layer can be adhered to the composite electrolyte membrane.

[0058] In another aspect, there is provided a redox flow battery comprising a composite electrolyte membrane described herein or a composite electrolyte membrane-electrode assembly described herein.

[0059] A redox flow battery can include a composite electrolyte membrane-electrode assembly described herein disposed between two bipolar plates. The membrane electrode assembly and bipolar plates can be held together by a frame.

[0060] In another embodiment, a) a first end plate; b) a first current collecting plate; c) a plurality of redox flow batteries as described herein connected in series; d) a second current collector, and e) a second end plate; A redox flow battery stack comprising: the plurality of redox flow batteries are disposed between the first current collector plate and the second current collector plate; and The redox flow battery stack may further include a housing, wherein the first end plate is disposed adjacent to the first current collector plate and the second end plate is disposed adjacent to the second current collector plate.

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

[0062] In another aspect, there is provided a method for producing a composite electrolyte membrane as described herein, the method comprising: a) providing a support layer for a composite electrolyte membrane; b) disposing a layer of a first liquid ionomer composition on said support layer; c) disposing a porous layer comprising a microporous polymer structure on the layer of the first liquid ionomer composition, at least partially embedding the ion exchange material of the first liquid ionomer composition within the microporous polymer structure of the porous layer to render the microporous polymer structure occlusive, and optionally applying pressure to the porous layer to laminate the composite electrolyte membrane; and d) drying the composite to remove the liquid component; A method is provided, comprising:

[0063] This method further comprises, after step c) or d), e) disposing a layer of a second liquid ionomer composition on a surface of the support layer opposite to the surface on which the first liquid ionomer composition is disposed; and It may further comprise: f) drying the composite to remove the liquid component. When steps e) and f) are present, the drying step d) may be optional.

[0064] In some embodiments, the method may include a drying step after disposing or coating each layer of the liquid ionomer composition. In other embodiments, the method may include a drying step after disposing or coating several (but not every) layers of the liquid ionomer composition. In other embodiments, the method does not include a drying step between the application of different layers of the liquid ionomer composition, but only a final drying step of drying the composite to remove any liquid components. For the avoidance of doubt, in all embodiments, the method includes a final drying step of drying the composite to remove any liquid components.

[0065] In another aspect, there is provided a method for making a composite electrolyte membrane as described herein, the method comprising: a) providing a support layer for a composite electrolyte membrane; b) disposing a layer of a first liquid ionomer composition on said support layer; c) providing at least one porous layer comprising a microporous polymer structure and having a first surface and a second surface, and disposing the first surface of the at least one porous layer on the layer of the first liquid ionomer composition; d) disposing a layer of the first liquid ionomer composition on the second surface of the at least one porous layer to completely imbibe the microporous polymer structure and render the microporous polymer structure occlusive; and e) drying the composite to remove the liquid component; A method is provided, comprising:

[0066] Step d) of disposing a second layer of the first liquid ionomer composition on the second surface of the at least one porous layer and allowing it to be completely absorbed into the microporous polymer structure can be accomplished by applying pressure (e.g., using a kiss roll) on the second surface of the at least one porous layer to draw the first liquid ionomer composition all the way to the second surface, thereby allowing the microporous polymer structure to become completely occlusive. Alternatively or additionally, step d) of disposing a second layer of the first liquid ionomer composition on the second surface of the at least one porous layer and allowing it to be completely absorbed into the microporous polymer structure can be accomplished by layering (by any suitable liquid layer deposition means) an additional layer of the first liquid ionomer composition on the second surface of the at least one porous layer, thereby allowing the microporous polymer structure to become completely occlusive.

[0067] This method is f) disposing a layer of a second liquid ionomer composition over the layer of the first liquid ionomer composition on a second surface of the at least one porous layer; and g) drying the composite to remove the liquid component; The method may further include the step of:

[0068] In another aspect, there is provided a method for making a composite electrolyte membrane as described herein, the method comprising: a) providing a support layer for a composite electrolyte membrane; b) disposing a layer of a first liquid ionomer composition on said support layer; c) providing a porous layer comprising a microporous polymer structure and having a first surface and a second surface; d) disposing a first surface of the porous layer over the layer of the first liquid ionomer composition, causing the ion exchange material of the first liquid ionomer composition to be at least partially embedded within the microporous polymer structure and rendering the microporous polymer structure occlusive; e) disposing a layer of a second liquid ionomer composition on a second surface of the porous layer; and f) drying the composite to remove the liquid component; A method is provided, comprising:

[0069] The first liquid ionomer composition can include one or more ion exchange materials. The first liquid ionomer composition can include a liquid carrier. The liquid carrier can consist of a single liquid carrier or a mixture of liquid carriers. The liquid carrier can be a solvent or a mixture of solvents. The first liquid ionomer composition can be a solution of one or more ion exchange materials in the liquid carrier. The first liquid ionomer composition can be a dispersion of one or more ion exchange materials in the liquid carrier.

[0070] The second liquid ionomer composition can include one or more ion exchange materials. The second liquid ionomer composition can include a liquid carrier. The liquid carrier can consist of a single liquid carrier or a mixture of liquid carriers. The liquid carrier can be a solvent or a mixture of solvents. The second liquid ionomer composition can be a solution of one or more ion exchange materials in a liquid carrier. The first liquid ionomer composition can be a dispersion of one or more ion exchange materials in a liquid carrier.

[0071] The first liquid ionomer composition can be the same as the second liquid ionomer composition. The first liquid ionomer composition can be different from the second liquid ionomer composition. The first liquid ionomer composition and the second liquid ionomer composition can contain the same ion exchange material or multiple ion exchange materials. The first liquid ionomer composition can contain a different ion exchange material or a mixture of different ion exchange materials than the second liquid ionomer composition. The first liquid ionomer composition and the second liquid ionomer composition can contain the same liquid carrier or different liquid carriers. [Brief explanation of the drawings]

[0072] Brief description of the diagram [Figure 1A] FIG. 1A shows a schematic diagram of a composite electrolyte membrane according to one embodiment of the present disclosure.

[0073] [Figure 1B] FIG. 1B shows a schematic diagram of a composite electrolyte membrane according to another embodiment of the present disclosure.

[0074] [Figure 2] FIG. 2 shows a schematic diagram of a composite electrolyte membrane-electrode assembly according to one embodiment of the present disclosure.

[0075] [Figure 3A] FIG. 3A shows a schematic diagram of a composite electrolyte membrane according to an embodiment of the present disclosure before swelling.

[0076] [Figure 3B] FIG. 3B shows a schematic diagram of the composite electrolyte membrane of FIG. 3A assembled with electrodes and a frame, including positioning bars for mounting the membrane-electrode assembly in a cell stack.

[0077] [Figure 3C] FIG. 3C shows a schematic diagram of a state-of-the-art composite electrolyte membrane exhibiting undesirable (excessive) swelling.

[0078] [Figure 4] FIG. 4 shows a schematic diagram of a redox flow battery system including a composite electrolyte membrane according to the present disclosure.

[0079] [Figure 5] FIG. 5 shows a schematic diagram of a method for producing a composite electrolyte membrane according to the present disclosure.

[0080] [Figure 6] FIG. 6 shows a schematic diagram of an alternative method for producing a composite electrolyte membrane according to the present disclosure.

[0081] [Figure 7]FIG. 7 shows a schematic diagram of an alternative method for producing a composite electrolyte membrane according to the present disclosure.

[0082] [Figure 8] FIG. 8 shows a schematic view of the machine direction (MD) and transverse direction (TD) of a test specimen (eg, a composite electrolyte membrane or porous layer as described herein).

[0083] [Figure 9] FIG. 9 shows Table 1, which shows the properties of the composite membrane.

[0084] [Figure 10] FIG. 10 shows FIG. 2 and illustrates the properties of the porous layer including the microporous structure before being used in the composite electrolyte membrane of the example shown in Table 1. DETAILED DESCRIPTION OF THE INVENTION

[0085] Detailed Description The present inventors have surprisingly discovered that the composite electrolyte membranes of the present disclosure exhibit low dimensional change upon hydration, i.e., low swelling characteristics, particularly in the machine and cross directions of the membrane. This is particularly advantageous in redox flow battery applications, as these membranes provide good battery efficiency and do not exhibit blistering when the electrolyte membrane is assembled into a battery cell. Advantageously, the composite electrolyte membranes of the present disclosure can be assembled into redox flow battery cells using dry assembly methods without exhibiting significant swelling in the machine and cross directions after assembly. This significantly reduces manufacturing costs without compromising battery durability and efficiency.

[0086] The inventors have particularly surprisingly discovered that composite electrolyte membranes according to the present disclosure that include one or more porous layers that include a microporous polymer structure also exhibit the advantageous low swelling properties described above. Without wishing to be bound by theory, the composite electrolyte membrane according to the present disclosure has a high elastic modulus (e.g., an elastic modulus in MD of greater than about 450 MPa at 50% relative humidity and an elastic modulus in MD and TD (e.g., in a first direction and a second direction of the composite electrolyte membrane) of greater than about 300 MPa at about 100% relative humidity), and at least one porous layer comprising a microporous polymer structure and having an absolute ratio of elastic strength in MD and TD of about 0.45 to about 2.20 can achieve surprisingly low swelling ratios (e.g., up to 8% in MD and up to 7% in TD). Furthermore, the present inventors have surprisingly discovered that a composite electrolyte membrane comprising one or more porous layers comprising a microporous polymer structure having high elastic strength (e.g., about 30 N / m) in both the machine direction and the cross direction (MD and TD) of the composite electrolyte membrane exhibits low swelling ratios in the machine direction and the cross direction (e.g., up to 8% in MD and up to 8% in TD).

[0087] The low swelling membrane of the present disclosure also exhibits low or minimal crossover of active species. Without wishing to be bound by theory, this can be achieved by providing at least one porous layer comprising a microporous polymer structure. It was surprising that even a single porous layer comprising a microporous polymer structure was sufficient to provide the required low swelling and low crossover properties of the membrane.

[0088] In the context of this disclosure, elastic strength is defined as the gradient of strain in a material (e.g., a porous layer or composite electrolyte membrane) produced by an applied stress (force per unit width) multiplied by the sample thickness in the elastic region of the material's response. The elastic strength of a sample can be calculated by multiplying the elastic modulus, as assessed by ASTM Method D882-18, August 2018, entitled "Standard Test Method for Tensile Properties of Thin Plastic Sheets," by the sample thickness. The total porous layer elastic strength is the sum of the elastic strengths of all porous layers present in the composite electrolyte membrane.

[0089] In the context of this disclosure, ultimate tensile strength (or tensile strength before breakage) refers to the maximum stress a material can withstand while being stretched or pulled before breaking, as assessed by ASTM Method D882-18, August 2018, entitled "Standard Test Method for Tensile Properties of Thin Plastic Sheets." Ultimate tensile strength refers to the maximum tensile stress from a stress-strain curve. Ultimate tensile strength of a composite electrolyte membrane refers to the relative tensile strength of the composite electrolyte membrane, normalized by thickness and expressed in force per unit area (MPa). Ultimate web tensile strength of at least one porous layer refers to the absolute tensile strength of the porous layer, not normalized by thickness and expressed in N / m. Total porous layer ultimate web tensile strength is the sum of the ultimate web tensile strengths of all porous layers present in the composite electrolyte membrane.

[0090] In the context of this disclosure, modulus of elasticity is defined as the gradient of strain in a material (e.g., a composite electrolyte membrane) produced by a specific applied stress in the elastic region of the material's response, per ASTM Method D882-18, August 2018, entitled "Standard Test Method for Tensile Properties of Thin Plastic Sheets." Modulus of elasticity is obtained from tensile strength testing as described herein. Modulus of elasticity is expressed in force per unit area, typically expressed in megapascals (MPa).

[0091] Without wishing to be bound by theory, the absolute ratio of the elastic modulus of the composite electrolyte membrane in the first axial direction and the second axial direction of the composite electrolyte membrane may be equal to the absolute ratio of the elastic strength of the composite electrolyte membrane in the first axial direction and the second axial direction of the composite electrolyte membrane. The absolute ratio of the elastic modulus of the at least one porous layer of the composite electrolyte membrane in the first axial direction and the second axial direction of the composite electrolyte membrane may be equal to the absolute ratio of the elastic strength of the at least one porous layer of the composite electrolyte membrane in the first axial direction and the second axial direction of the composite electrolyte membrane.

[0092] FIG. 1A shows a composite electrolyte membrane 100 according to one embodiment of the present disclosure. In this embodiment, the composite electrolyte membrane has a support or backer layer 160. The composite electrolyte membrane includes a porous layer 110 that includes a microporous polymer structure 120 and an ion exchange material 130 that is at least partially embedded within the microporous polymer structure 120, rendering the microporous polymer structure 120 occlusive. In the embodiment of FIG. 1, the ion exchange material 130 is completely embedded within the microporous polymer structure 120. The porous layer 110 can include a microporous polymer structure 120 that includes a fluoropolymer. For example, the porous layer 110 can include ePTFE. However, the porous layer 110 can include any microporous polymer structure 120, as described herein above.

[0093] The composite electrolyte membrane 100 has a first layer 140a of ion exchange material and a second layer 140b of ion exchange material. The first and second layers of ion exchange material may not be reinforced by a porous layer. The composite electrolyte membrane is a laminate. The composite electrolyte membrane has a thickness 150.

[0094] FIG. 1B illustrates a composite electrolyte membrane 100′ according to one embodiment of the present disclosure. The composite electrolyte membrane includes two porous layers 110a and 110b, each including a microporous polymer structure 120a and 120b, and an ion exchange material 130 at least partially embedded within the microporous polymer structures 120a,b, causing the microporous polymer structures 120a,b to be occlusive. In the embodiment of FIG. 1B, the ion exchange material 130 is completely embedded within the microporous polymer structures 120a,b. The porous layers 110a,b can include the microporous polymer structures 120a,b including a fluoropolymer. For example, the porous layers 110a,b can include ePTFE.

[0095] The composite electrolyte membrane 100' has a first layer 140a of ion exchange material disposed on the outer surface of the porous layer 110a and a second layer 140b of ion exchange material disposed on the outer surface of the porous layer 110b. The composite electrolyte membrane 100' includes a third layer 140c of ion exchange material between the porous layers 110a and 110b. The first, second, and third layers of ion exchange material may be unreinforced layers of ion exchange material (i.e., the IEM is not reinforced by or substantially absorbed in the porous layers). The composite electrolyte membrane 100' is a laminate. The composite electrolyte membrane 100' has a thickness 150'.

[0096] The composite electrolyte membrane may have an elastic modulus in the first axial direction of the composite electrolyte membrane of greater than about 450 MPa at 50% relative humidity. The composite electrolyte membrane may have an elastic modulus in the second axial direction of the composite electrolyte membrane of greater than about 450 MPa at 50% relative humidity. The porous layer 110 including the microporous polymer structure may have an elastic strength of at least about 30 N / m in the first axial direction (e.g., MD) and the second axial direction (e.g., TD) of the porous layer 110. The absolute ratio of the elastic strength of the porous layer 110 in the first axial direction (MD) of the porous layer 110 to the elastic strength of the porous layer 110 in the second axial direction (TD) of the porous layer 110 may be about 0.45 to about 2.20. The composite electrolyte membrane 100 may have an elastic modulus in the first axial direction (MD) of the composite electrolyte membrane 100 of greater than 300 MPa at about 100% relative humidity. The composite electrolyte membrane 100 may have an elastic modulus in the second axis direction (TD) of the composite electrolyte membrane 100 of greater than 300 MPa at about 100% relative humidity. The porous layer 110 may have an elastic strength of at least about 30 N / m in the first axis direction (e.g., MD) and the second axis direction (e.g., TD) of the porous layer 110, as measured according to the Tensile Strength Test described herein.

[0097] FIG. 2 shows a composite electrolyte membrane-electrode assembly 300 according to one embodiment of the present disclosure. The membrane electrode assembly 300 includes a composite electrolyte membrane 200 as described herein. The properties described for the composite electrolyte membrane 100 also apply to the composite electrolyte membrane 200. The composite electrolyte membrane 200 includes a first layer 240a of ion exchange material and a second layer 240b of ion exchange material disposed on opposite sides of a porous layer 210. The porous layer 210 includes a microporous polymer structure 220 and an ion exchange material 230 at least partially embedded within the microporous polymer structure 220, causing the microporous polymer structure 220 to be occlusive. The composite electrolyte membrane 200 has a thickness 250. The first and second layers of ion exchange material may not be reinforced by a porous layer.

[0098] Compressed against the first layer 240a of ion exchange material is a first electrode 310a. Compressed against the second layer 240b of ion exchange material of the composite electrolyte membrane 200 is a second electrode 310b. One or both of electrodes 310a and / or 310b can be porous layers. One or both of electrodes 310a and / or 310b can be selected from felt, paper, or woven materials.

[0099] 3A shows a schematic diagram of a composite electrolyte membrane 400 according to an embodiment of the present disclosure prior to swelling. Composite electrolyte membrane 400 can have any of the properties described above for composite electrolyte membranes 100 and 200. As shown in FIG. 3A, composite electrolyte membrane 400 has perforations 450 each configured to receive a positioning bar. In FIG. 3A, composite electrolyte membrane 400 is shown in its dry state (i.e., unswollen).

[0100] 3B shows a schematic diagram of a redox flow battery cell 600 including the composite electrolyte membrane 400 of FIG. 3A assembled with electrodes 500 a and 500 b disposed on either side of the membrane 400, a frame 620, and a positioning bar 630 for mounting the membrane-electrode assembly in a cell stack. Even after contact with water, the composite electrolyte membrane 400 does not exhibit substantial changes in the machine and / or cross directions. Therefore, even if the composite electrolyte membrane 400 is assembled into the redox flow battery cell 600 using a dry approach, the redox flow battery cell 600 does not exhibit blistering, and the efficiency and lifetime of the cell are improved compared to state-of-the-art composite electrolyte membranes.

[0101] FIG. 3C shows a schematic diagram of a state-of-the-art composite electrolyte membrane 400′ that exhibits undesirable (excessive) swelling after contact with water. As can be seen, in this prior art, the positioning bars no longer align with the perforations in the membrane 400′ because the membrane's swelling changes its dimensions in the machine direction (MD) and transverse direction (TD). If the membrane is assembled using a dry approach, this change in the membrane's 400′ dimensions after assembly and contact with the solution can be detrimental, potentially causing the membrane 400′ to sag on the frame around which it is mounted, potentially reducing the membrane's performance during operation. Furthermore, this change in dimensions upon swelling can damage the membrane 400′ (e.g., tears or cuts can appear in the membrane material at the interface with the frame).

[0102] FIG. 4 shows a schematic diagram of a redox flow battery system including a composite electrolyte membrane according to the present disclosure. As shown in FIG. 4, a flow battery 700 is provided according to an embodiment of the present disclosure. The flow battery 700 is a fully rechargeable electrical energy storage device that includes a reservoir 710 containing a catholyte or positive electrolyte 720 and a second reservoir 730 containing an anolyte or negative electrolyte 740. The catholyte 720 can be an electrolyte containing specific redox ions that are in an oxidized state and are reduced during the discharge process of the flow battery 700, or in a reduced state and are oxidized during the charge process of the flow battery 700, or it is a mixture of these oxidized ions and ions to be oxidized. The anolyte 740 can be an electrolyte containing redox ions that are in a reduced state and are oxidized during the discharge process of the flow battery 700, or in an oxidized state and are reduced during the charge process of the flow battery 700, or it is a mixture of reduced ions and ions to be reduced.

[0103] Catholyte 720 is circulated via pump 750 through an exchange region 760 that includes a composite electrolyte membrane 765 according to the present disclosure disposed between a first electrode 770 and a second electrode 780. Anolyte 740 is also circulated via pump 790 through exchange region 760. Composite electrolyte membrane 765 is fabricated according to embodiments of the present invention (see, e.g., FIGS. 5-7).

[0104] In some embodiments, the amount of catholyte 720 and anolyte 740 supplied to exchange region 760 can vary depending on the pumping action of pumps 750 and 790, and therefore the amount of power generated by the electrolyte reaction in exchange region 760 can vary. Both catholyte 720 and anolyte 740 circulate within their respective spaces, promoting reduction / oxidation chemical processes on either side of composite electrolyte membrane 765 and generating an electrical potential. The cell voltage can be determined chemically by the Nernst equation and ranges from 0.5 to 5.0 volts or 0.8 to 1.7 volts.

[0105] 5, an exemplary flow diagram of a method 800 illustrates forming a composite electrolyte membrane 870 having a porous layer 810 of a microporous polymer structure, an ion exchange material 830 fully embedded within the microporous polymer structure, an additional layer 840a of ion exchange material, and an uncoated non-blocking layer 822. The method 800 includes providing a support layer, such as a backer 860.

[0106] Suitable support layers can include woven materials, such as scrims made from woven expanded porous polytetrafluoroethylene fibers, webs made from extruded or oriented polypropylene or polypropylene netting (available from Conwed, Inc. of Minneapolis, Minnesota), and woven polypropylene and polyester materials (available from Tetko Inc. of Burial Cliff, New York). Suitable nonwoven materials can include, for example, spunbond polypropylene from Reemay Inc. of Old Hickory, Tennessee. The support structure may comprise 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"). The support structure may also include a protective layer which may comprise 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").

[0107] The support layer can optionally include a reflective layer comprising a metal substrate (e.g., an aluminum substrate). The specific metal selected can vary widely, so long as it is reflective. A non-limiting list of exemplary metals includes aluminum, beryllium, cerium, chromium, copper, germanium, gold, hafnium, manganese, molybdenum, nickel, platinum, rhodium, silver, tantalum, titanium, tungsten, zinc, or alloys such as Inconel or bronze. The reflective layer can optionally include a mixture or alloy of two or more metals, optionally including two or more of the above metals. The reflective layer can optionally include a highly reflective polymer multilayer film, such as Vikuiti™ Enhanced Specular Reflector available from 3M. In yet another example, the reflective layer can optionally include a highly reflective non-metallic inorganic dielectric multilayer film, including materials such as magnesium fluoride, calcium fluoride, titanium dioxide, and silicon dioxide.

[0108] In step 882 of Figure 5, the ion exchange material is applied as a layer 830 of controlled thickness to the support structure 860 in a single-pass or multiple-pass ionomer coating technique, including forward roll coating, reverse roll coating, gravure coating, doctor coating, kiss coating, slot die coating, slide die coating, and dipping, brushing, painting, and spraying. The ion exchange material layer 830 can be prepared by dissolving the ion exchange material in a solvent. The ion exchange material layer 830 can be prepared by suspending the ion exchange material in a carrier. The ion exchange material can include an ion exchange material and a solvent, and optionally, additional components such as a surfactant. In some embodiments, the ion exchange material is a cation exchange material, an anion exchange material, or an ion exchange material containing both cation and anion exchange capabilities. The choice of solvent or carrier can depend, in part, on both the composition of the ionomer and the composition of the porous substrate.

[0109] In step 884 of Figure 5, one porous layer 820 comprising a microporous polymer structure is laminated onto at least a portion of ion exchange material layer 830 by any conventional technique, such as, for example, hot roll lamination, ultrasonic lamination, adhesive lamination, contact lamination, or forced hot air lamination, so long as the technique does not compromise the integrity of the intact microporous polymer structure. In some embodiments, porous layer 820 comprises ePTFE having a microporous polymer structure. Porous layer 820 can be characterized by a uniform structure and composition throughout its thickness. Alternatively, the structure and composition of porous layer 820 can vary throughout its thickness. Imbibed porous layer 810 is formed when porous layer 820 is at least partially imbibed with ion exchange material layer 830.

[0110] In step 886 of FIG. 5 , the porous layer 810, including the microporous polymer structure and at least partially imbibed with the ion exchange material 830, is placed in an oven for drying and thermal annealing to complete the construction of the composite electrolyte membrane 870. If the method involves adding additional layers, the drying step may be omitted until all layers have been applied. The composite membrane can then be subjected to a final drying step. The oven temperature can be greater than 60°C, e.g., 60-220°C or 150-200°C. Drying and thermal annealing the treated microporous polymer structure in the oven ensures that the ion exchange material adheres to the internal membrane surface and, optionally, to the external membrane surface, e.g., the fibrils and / or nodes of the microporous polymer structure. The resulting dried and annealed composite electrolyte membrane 870 can have a thickness of about 20 μm to about 40 μm, as measured at 25°C and 50% relative humidity in the thickness measurement test described herein. The composite electrolyte membrane 870 can have a composite electrolyte membrane machine direction elastic modulus of greater than about 450 MPa at 50% relative humidity when measured according to the Tensile Strength Test described herein. The composite electrolyte membrane 870 can have a composite electrolyte membrane cross direction elastic modulus of greater than about 450 MPa at 50% relative humidity when measured according to the Tensile Strength Test described herein. The composite electrolyte membrane 870 can have a composite electrolyte membrane machine direction elastic modulus of at least about 300 MPa at 100% relative humidity when measured according to the Tensile Strength Test described herein. The composite electrolyte membrane 870 can have a composite electrolyte membrane cross direction elastic modulus of at least about 300 MPa at 100% relative humidity when measured according to the Tensile Strength Test described herein. The at least one porous layer 820 comprising a microporous polymer structure can have an elastic strength of at least about 30 N / m in the machine direction and the cross direction of the at least one porous layer 820 when measured according to the Tensile Strength Test described herein. The absolute ratio of the elastic strength of the at least one porous layer 820 in the machine direction to the elastic strength of the at least one porous layer 820 in the cross direction is from about 0.45 to about 2.20.The absolute ratio of the modulus of elasticity of the at least one porous layer 820 in the machine direction to the modulus of elasticity of the at least one porous layer 820 in the cross direction is from about 0.45 to about 2.20.

[0111] 5, coating step 882 can be repeated with an additional layer or layers of ion exchange material when coating composite membrane 870 (before or after drying step 886). The ion exchange material of the additional layer or layers can be the same or different from the ion exchange material of ion exchange material layer 830. The composite membrane can be dried after each coating step or can be subjected to a single final drying step after all layers of ion exchange material have been deposited. 6, an exemplary flow diagram of method 900 illustrates forming a composite electrolyte membrane 970 having a porous layer 910 including a microporous polymer structure at least partially embedded with ion exchange material 930, an additional layer 940a of unreinforced ion exchange material, and a partially coated non-occlusive layer 922. Method 900, similar to method 800, includes providing a support layer (e.g., backer) 960, such as a woven material.

[0112] In step 982 of Figure 6, an ion exchange material is applied to a support layer 960 (backer) as a controlled thickness layer 930, similar to step 882 of method 800 of Figure 5. Step 982 is omitted because it is identical to step 882 of method 800 described above.

[0113] 6, a porous layer 920 comprising a microporous polymer structure is laminated onto a first portion of the layer of ion exchange material 930 by any conventional technique, such as hot roll lamination, ultrasonic lamination, adhesive lamination, contact lamination, or forced hot air lamination, so long as the technique does not destroy the integrity of the original microporous polymer structure. In some embodiments, the porous layer 920 comprises ePTFE having a microporous polymer structure. The microporous polymer structure can be characterized by a uniform structure and composition throughout its thickness. Alternatively, the structure and composition of the microporous polymer structure can vary throughout its thickness.

[0114] After lamination, the top of the porous layer 920 containing the microporous polymer structure can be coated with, for example, an ion exchange material (ionomer) coating (not shown) using a touch roll 950. This can be applied as a separate layer, or the ion exchange material can be drawn onto the surface of the porous layer 920 by applying pressure to the porous layer with the touch roll 950.

[0115] Step 986 of Figure 6 is similar to step 886 of method 800 of Figure 5. Therefore, a description of step 986 will be omitted here. The properties of the composite electrolyte membrane 970 can be as described above.

[0116] 6, coating step 982 can be repeated with an additional layer or layers of ion exchange material on composite membrane 970 (before or after drying step 986). The ion exchange material can be the same or different from that of layer 930. The composite membrane can be dried after each coating step, or can be subjected to a single final drying step as 986 after all layers of ion exchange material have been deposited.

[0117] 7, an exemplary flow diagram of method 1000 illustrates forming a composite electrolyte membrane 1070 having a layer 1010 comprising an ion exchange material at least partially embedded within a microporous polymer structure and two additional layers 1040a and 1040b of unreinforced ion exchange material disposed on either side of the fully imbibed layer 1010 comprising the microporous polymer structure. Method 1000, similar to methods 800 and 900, includes providing a support layer (e.g., backer) 1060, such as a woven material.

[0118] In step 1082 of Figure 7, a first layer 1030 of ion exchange material is applied to a support layer (backer), with layer 1030 having a controlled thickness similar to step 882 of method 800 of Figure 5. A description of step 1082 is omitted because it is identical to step 882 of method 800 described above.

[0119] 7, a porous layer 1020 comprising a microporous polymer structure is laminated onto a first portion of a first layer 1030 of ion exchange material (ionomer solution 1) by any conventional technique, such as hot roll lamination, ultrasonic lamination, adhesive lamination, contact lamination, or forced hot air lamination, so long as the technique does not compromise the integrity of the microporous polymer structure of layer 1020. Porous layer 1020 can comprise ePTFE having a microstructure of uniform structure and composition throughout its thickness. Alternatively, the structure and composition of the microporous polymer structure can vary throughout its thickness.

[0120] Step 1084 may be optionally followed by a drying step (not shown), similar to step 1088. In some embodiments, there is no drying step after laminating the porous layer 1020 in step 1084.

[0121] After lamination (and optionally after a drying step), in step 1086, a second layer 1030′ ion exchange material (ionomer solution 2) is applied as a layer of controlled thickness to the upper surface 1022 of the porous layer 1020 containing the microporous polymer structure using ionomer coating techniques, including forward roll coating, reverse roll coating, gravure coating, doctor coating, kiss coating, slot die coating, slide die coating, and ionomer coating techniques, including dipping, brushing, painting, and spraying. The first and second ion exchange materials can be prepared by dissolving the ion exchange material in a solvent. The first and second ion exchange materials can include an ion exchange material, a solvent, or a carrier, and optionally, can include additional components such as surfactants. In some embodiments, the ion exchange material is a cation exchange material, an anion exchange material, or an ion exchange material containing both cation and anion exchange capabilities. The choice of solvent or carrier can depend, in part, on both the composition of the ionomer and the composition of the porous substrate.

[0122] Step 1088 is similar to step 886 of method 800 of Figure 5. Therefore, a description of step 1088 will be omitted here. The prepared or obtained composite electrolyte membrane 1070, which has been dried and annealed, can have any of the properties described herein above.

[0123] Methods 800, 900, and 1000 can include the optional steps of submerging the composite electrolyte membrane and boiling the composite electrolyte membrane. For example, in embodiments using a surfactant, the composite electrolyte membrane can be further treated to remove the surfactant. This can be accomplished by soaking or submerging the composite electrolyte membrane in a solution of, for example, water, isopropyl alcohol, hydrogen peroxide, methanol, and / or glycerin. During this step, the surfactant that is initially mixed with the ion exchange material in the solution is removed. This soaking or submersion causes slight swelling of the composite electrolyte membrane, but the ion exchange material remains within the interior volume of the porous substrate.

[0124] As shown in Figures 5, 6, and 7, the composite electrolyte membrane 870, 970, 1070 includes at least one porous layer 820, 920, 1020 comprising a microporous polymer structure and an ion exchange material 830, 930, 1030 (e.g., an ionomer) at least partially impregnated in the microporous polymer structure. The ion exchange material can substantially impregnate the microporous polymer structure of the porous layer 820, 920, 1020, rendering the interior volume substantially occlusive (i.e., the interior volume has a structure characterized by a low void volume and high impermeability to gases). For example, filling more than 90% of the interior volume of the microporous polymer structure with ion exchange material results in substantial occlusion, and the membrane is characterized by a Gurley number greater than 10,000 seconds. The ion exchange material is firmly adhered to the interior and exterior surfaces of the microporous polymer structure of the porous layers 820 , 920 , 1020 , eg, to the fibrils and / or nodes of the microporous polymer structure, to form the absorbent layers 810 , 910 , 1010 .

[0125] In some embodiments, in addition to being impregnated into a microporous polymer structure to form the absorbent layer 810, 910, 1010, the ion exchange material is provided as one or more additional non-reinforced layers 840a, 940a, 1040a, 1040b on one or more outer surfaces of the absorbent layer 810, 910, 1010.

[0126] 5, a portion of the microporous polymer structure of the porous layer 820 (e.g., the top or bottom region) can include a non-blocking layer (i.e., an interior volume characterized by a high void volume and having a structure that is highly permeable to gases) that is free or substantially free of ion exchange material 830. The location of the non-blocking layer 822 is not limited to the top region of the porous layer 830. As noted above, the non-blocking layer 822 can be provided on the bottom region of the absorbent porous layer 810.

[0127] 6, the non-occlusive layer 922 may include a small amount of ion exchange material present as a thin node and fibril coating on the inner surface of the microporous polymer structure of the porous layer 920. However, the amount of ion exchange material may not be large enough to cause the microporous polymer structure to become occlusive, thereby forming the non-occlusive layer 922.

[0128] In some embodiments, the composite electrolyte membrane 870, 970, 1070 can be provided on a support layer 860, 960, 1060. The support layer 860, 960, 1060 can include a backer, release film, for example, a cycloolefin copolymer (COC) layer. In some embodiments, the composite electrolyte membrane 870, 970, 1070 can be peeled (or separated) from the support layer 860, 960, 1060 before being incorporated into a membrane electrode assembly (MEA).

[0129] 5-7 show exemplary composite electrolyte membranes 870, 970, 1070 that include a single type of ion exchange material. However, applications are not limited to composite electrolyte membranes with a single type of ion exchange material or a single absorbent layer 810, 910, 1010.

[0130] 8 shows a schematic representation of the machine direction (MD) and transverse direction (TD) of a sample. Without wishing to be bound by theory, the machine direction may correspond to the Y axis of the sample, the transverse direction may correspond to the X axis of the sample, and the thickness of the sample may correspond to the Z axis of the sample.

[0131] Test procedures and measurement protocols used in the examples While 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 will be understood that aspects of the present invention, parts of various embodiments, and various features recited above and / or in the appended claims can be combined or interchanged in whole or in part. In the foregoing description of various embodiments, embodiments that refer to separate 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 understand that the foregoing description is merely exemplary and is not intended to limit the present invention.

[0132] Thickness Samples were prepared and characterized in a cleanroom with a cleanliness class of 10,000 at 23°C ± 2°C and 50 ± 10% relative humidity. Test materials were cut into 48 mm diameter circles using a punch press. Samples were allowed to equilibrate for at least 1 hour in the thickness measurement room before measurement. A thickness gauge (DE12BR (Sony Precision Technology), flat stylus φ6.5 mm) was contacted with each sample, and gauge height readings were recorded at three different spots on the membrane. The measurement pressure was 0.7 ± 0.2 N, with a minimum scale of 1 / 10,000 mm. Relative humidity was measured using an RH probe "HN-C" (obtained from Chino Corporation, Japan). For the avoidance of doubt, the thickness of the composite electrolyte membrane is measured on the complete laminate, including at least one porous layer comprising a microporous polymer structure and an ion exchange material at least partially embedded within and occluding said microporous polymer structure. The thickness of the porous layer was performed on the untreated porous layer (ie, the pristine porous layer without any ion exchange material embedded therein).

[0133] The thickness of the composite electrolyte membrane at 0% RH was calculated using the following general formula:

number

number

[0134] Volume fraction of microporous polymer structure (MPS) in composite electrolyte membranes The volume percentage of the microporous polymer structure in each composite electrolyte membrane was calculated according to the following formula:

number

[0135] The microporous polymer structure used in these examples was ePTFE. The matrix skeletal density of ePTFE is 2.25 g / cm 3 It was determined that this was the case.

[0136] Tensile strength of composite electrolyte membrane Tensile strength measurements of the composite electrolyte membranes were performed according to ASTM D822-18 using a Tensilon RTG-1250 (A&D Co., Ltd., Japan) with an 80 mm grip distance. Specimens were tested at a test speed of 200 mm / min with a 50 N load cell. All specimens were measured under constant temperature and humidity conditions of 23°C ± 2°C and 50% ± 10% relative humidity. It is also possible to measure tensile strength at different temperatures and relative humidity, for example, at approximately 95% relative humidity. Approximately 95% relative humidity can be achieved by using an RH environmental chamber for tensile strength measurements. Materials were cut along the machine direction (MD) or transverse direction (TD) using a punch press. Each specimen was gripped to prevent wrinkling. The initial force applied was 0.08 N and gradually increased until the specimen broke. The toe correction standard was 0.08 N. Ultimate tensile strength corresponds to the maximum tensile strength of a test specimen before it breaks. In other words, ultimate tensile strength is the maximum stress that a material can withstand when stretched or pulled before breaking. The ultimate tensile strength of a composite membrane is measured in MPa.

[0137] Elastic modulus of composite membrane In the context of this disclosure, modulus of elasticity is defined as the gradient of strain in a material (e.g., a composite electrolyte membrane) produced by a specific applied stress in the elastic region of the material's response, per ASTM Method D882-18, August 2018, entitled "Standard Test Method for Tensile Properties of Thin Plastic Sheets." Modulus of elasticity is obtained from tensile strength testing as described herein. Modulus of elasticity is expressed in force per unit area, typically in megapascals (MPa).

[0138] The elastic strength of the composite membrane is determined for each of the machine (MD) and transverse (TD) sample directions from the following formula: 3% Elastic Strength (N / m): Tensile strength (N / m) when I is 3% I=(L-L0) / L0×100 I = Engineering strain (yield elongation), % L = length between grips when yielding occurs, mm L0 = initial length between grips, mm

[0139] Over a strain range of 0.01 to 2%, the Tensilon RTG-1250 software collects multiple raw data points and calculates the difference between adjacent pairs of data points. The software then selects the second, third, and fourth largest changes. Finally, the software calculates the elastic strength by least-squares fitting a line through three data points in each of the machine direction (MD) and transverse direction (TD) sample directions.

[0140] The modulus is then calculated by dividing the 3% modulus by the thickness of the sample for each of the machine (MD) and transverse (TD) sample directions, as measured by a pressure gauge in the thickness test described herein. Thus, the modulus is related to the modulus, but is not normalized to the thickness of the specimen.

[0141] The absolute ratio of the elastic moduli of the composite electrolyte is calculated by the following formula: Modulus of elasticity of composite in first direction (MD) ÷ Modulus of elasticity of composite in second direction (TD)

[0142] Tensile and elastic strength of at least one porous layer comprising a microporous polymer structure Tensile strength tests of at least one porous layer containing a microporous polymer structure were performed using a 100 N tensile testing machine (Tensilon RTG-1250, A&D Co., Ltd., Japan) at a test speed of 200 mm / min. The tensile strength tests were performed on untreated porous layers (i.e., porous layers in their original state without embedded ion exchange materials). Specimens were cut into a dogbone shape and gripped so that the grip length was 80 mm. Tests were performed at constant temperatures and humidity levels of 23 ± 2°C and 50% ± 5%. A punch press was used to cut the material along the machine and transverse directions. The specimens were then clamped to prevent wrinkling, and strains were applied starting from 0.03 N and gradually increased until the specimen broke. The toe compensation criterion was 0.03 N. The ultimate web tensile strength of the at least one porous layer corresponds to the maximum force before the porous layer specimen broke, normalized to the sample width. The ultimate web tensile strength of the at least one porous layer is not normalized to the thickness of the porous layer and is measured in N / m. Thus, the ultimate web tensile strength characterizes the absolute strength of the at least one porous layer or the ultimate web tensile strength of the at least one porous layer.

[0143] The elastic strength of the at least one porous layer comprising a microporous polymer structure is determined for each of the machine (MD) and transverse (TD) sample directions from the following formula: 3% Elastic Strength (N / m): Tensile strength (N / m) when I is 3% I=(L-L0) / L0×100 I = Engineering strain (yield elongation), % L = length between grips when yielding occurs, mm L0 = original length between grips, mm

[0144] Over a strain range of 0.01 to 2%, the Tensilon RTG-1250 software collects multiple raw data points and calculates the difference between adjacent pairs of data points. The software then selects the second, third, and fourth largest changes. Finally, the software calculates the elastic strength by least-squares fitting a line through three data points in each of the machine direction (MD) and transverse direction (TD) sample directions.

[0145] The absolute ratio of the elastic strengths of the at least one porous layer is calculated as follows: Elastic strength of the porous layer in the first axis direction (MD) ÷ Elastic strength of the porous layer in the second axis direction (TD)

[0146] The total elastic strength of multiple porous layers used in a composite membrane is calculated by summing the elastic strength of each of the individual porous layers present in the composite membrane in each direction of the sample (i.e., machine direction (MD) and transverse direction (TD)).

[0147] The total porous layer ultimate web tensile strength of multiple porous layers used in a composite membrane is calculated by summing the ultimate web tensile strength (N / m) of each individual porous layer present in the composite membrane in each of the machine (MD) and transverse (TD) sample directions.

[0148] Equivalent weight (EW) The equivalent weight of the ionomer was calculated using an automatic potentiometric titrator, AT-610, with a closed cell unit (SCU-118) manufactured by Kyoto Electronics Manufacturing Co., Ltd. Measurements were performed on three 50 mm x 50 mm test specimens at 23°C ± 2°C. The test specimens were dried in a vacuum oven at 100°C for 2-3 hours. The dry weight of the test specimens was measured. The test specimens were placed in 25 ml of distilled water in a closed cell unit, the cell unit was evacuated, filled with nitrogen, and the cell was stirred for 15 minutes. Next, 55 ml of 3 M NaCl solution was added, and the closed cell was stirred for an additional 45 minutes. 0.01 M NaOH solution was titrated to pH 7.00. The EW was calculated from the titer (ml), NaOH concentration, and membrane weight using the following formula:

number

[0149] Swelling ratio of composite electrolyte membrane The swelling ratio was measured using a dimensional tester NEXIV VMR-3020 (Nikon) for a 50 × 60 mm rectangle drawn with a specified pen. The dry dimensions of each specimen in the machine direction (MD) and transverse direction (TD) were measured on a glass plate. The composite electrolyte membrane specimen was then placed in boiling distilled water for 10 minutes and then transferred to distilled water at 23°C ± 2°C. Finally, the specimen was transferred to a glass plate, and the machine direction and transverse direction dimensions of the swollen specimen (in the wet state) were measured. The swelling ratio was calculated using the following formula:

number

[0150] Mass per area Each microporous polymer structure and composite electrolyte membrane was distorted sufficiently to remove wrinkles and then cut into an 18 cm 2 x 48 mm diameter die using a die. 2 A piece was cut out. 18cm 2 The pieces were weighed on a conventional laboratory balance. 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. [Example]

[0151] example The composite membranes, devices, and methods of manufacture of the present disclosure can be better understood with reference to the following non-limiting examples.

[0152] Invention Example 1 A 37-micron (37 μm) thick composite electrolyte membrane containing a perfluorosulfonic acid resin ion exchange polymer with an EW of 920 g / eq, reinforced with one layer of expanded porous ePTFE membrane 1 (see details of the ePTFE in Membrane 1 in Table 2), was prepared using conventional laboratory techniques. First, a water-ethanol-based solution of perfluorosulfonic acid resin with an EW of 920 g / eq (obtained from Asahi Glass Co., Ltd., Japan) at 18% solids was coated onto a moving substrate layer using a roll transfer method to a target nominal wet coating thickness of 370 μm, followed by lamination with ePTFE membrane #1. The substrate layer was a polymer sheet (obtained from Daicel Value Coating Co., Ltd., Japan) containing PET and a protective layer of cyclic olefin copolymer (COC), oriented with the COC side facing up. The laminate was then dried in an oven at 130 °C for 3 minutes. The air side of the dried membrane was then coated with the same perfluorosulfonic acid resin at 8% solids using a roll transfer method, targeting a nominal wet coating thickness of 120 microns, and dried in an oven at 130°C for 1.5 minutes. The dried membrane was finally annealed at 190°C for 3 minutes. The resulting composite electrolyte membrane, comprising a substrate layer bonded to an ion-exchange polymer layer, followed by a microporous polytetrafluoroethylene membrane layer with an ion-exchange polymer embedded therein, had a total thickness of 37 microns and a mass of 75 g / m at 50% RH. 2 had a mass / area of

[0153] Invention Example 2 A 34-micron-thick composite electrolyte membrane containing a perfluorosulfonic acid resin ion-exchange polymer with an EW of 920 g / eq, reinforced with one layer of expanded porous ePTFE membrane #2, was prepared using conventional laboratory techniques. First, a water-ethanol-based solution of perfluorosulfonic acid resin with an EW of 920 g / eq at 21% solids (obtained from Asahi Glass Co., Ltd., Japan) was coated onto a moving substrate layer using a roll transfer method, aiming for a nominal wet coating thickness of 290 microns, and then laminated with ePTFE membrane #2. The substrate layer was a polymer sheet (obtained from Daicel Value Coating Co., Ltd., Japan) containing PET and a protective layer of cyclic olefin copolymer (COC), oriented with the COC side facing up. The laminate was then dried in an oven at 130 °C for 0.8 min. The air side of the dried membrane was then coated with the same perfluorosulfonic acid resin at 16% solids using a roll transfer method, targeting a nominal wet coating thickness of 85 microns, and dried in an oven at 160°C for 0.8 minutes. The dried membrane was finally annealed at 190°C for 3 minutes. The resulting composite electrolyte membrane, comprising a substrate layer bonded to an ion-exchange polymer layer, followed by a microporous polytetrafluoroethylene membrane layer with an ion-exchange polymer embedded therein, had a total thickness of 34 microns and a mass of 69 g / m at 50% RH. 2 had a mass / area of

[0154] Invention Example 3 A 29-micron-thick composite electrolyte membrane containing a 920 g / eq EW perfluorosulfonic acid resin ion-exchange polymer reinforced with one layer of expanded porous ePTFE membrane #3 was prepared using conventional laboratory techniques. First, a water-ethanol-based solution of the perfluorosulfonic acid resin (obtained from Asahi Glass Co., Ltd., Japan) with an EW of 920 g / eq was coated at a 22% solids concentration onto a moving substrate layer using a roll-transfer method, aiming for a nominal wet coating thickness of 200 microns, and then laminated with the ePTFE membrane #3. The substrate layer was a polymer sheet (obtained from Daicel Value Coating Co., Ltd., Japan) containing PET and a protective layer of cyclic olefin copolymer (COC), oriented with the COC side facing up. The laminate was then dried in an oven at 160 °C and annealed at that temperature for 3 minutes to produce a solid coating structure comprising the substrate layer bonded to the polymer layer reinforced with expanded porous polytetrafluoroethylene. The resulting composite electrolyte membrane comprised a substrate layer bonded to an ion-exchange polymer layer, followed by a microporous polytetrafluoroethylene membrane layer with an ion-exchange polymer embedded therein, and had a total thickness of 29 microns and a mass of 58 g / m at 50% RH. 2 The resulting composite electrolyte membrane was characterized by having an ion exchange material embedded within the microporous polymer structure, leaving a non-occluding portion of the microporous polymer structure nearest the first surface, and a layer of ion exchange material less than 1 micron thick on the second surface of the microporous polymer structure.

[0155] Example 4 A 30-micron-thick composite electrolyte membrane containing an ion-exchange polymer, perfluorosulfonic acid resin, with an EW of 810 g / eq, reinforced with one layer of expanded porous ePTFE membrane #4 was prepared using conventional laboratory techniques. First, a 23% solids concentration of a water-ethanol-based solution of perfluorosulfonic acid resin with an EW of 810 g / eq (obtained from Asahi Glass Co., Ltd., Japan) was coated onto a moving substrate layer using a roll-transfer method, aiming for a nominal wet coating thickness of 200 microns, and then laminated with ePTFE membrane #4. The substrate layer was a polymer sheet (obtained from Daicel Value Coating Co., Ltd., Japan) containing PET and a protective layer of cyclic olefin copolymer (COC), oriented with the COC side facing up. The laminate was then dried in an oven at 160 °C and annealed at that temperature for 3 minutes to produce a solid coating structure comprising the carrier substrate bonded to the polymer layer reinforced with expanded porous polytetrafluoroethylene. The resulting composite electrolyte membrane comprises a substrate layer bonded to an ion-exchange polymer layer, followed by a microporous polytetrafluoroethylene membrane layer with an ion-exchange polymer embedded therein, and has a total thickness of 30 microns and a mass of 61 g / m at 50% RH. 2 The resulting composite electrolyte membrane was characterized by having an ion exchange material embedded within the microporous polymer structure, leaving an unoccluded portion of the microporous polymer structure nearest the first surface, and a layer of ion exchange material less than 1 micron thick on the second surface of the microporous polymer structure.

[0156] Invention Example 5 A 29-micron-thick composite electrolyte membrane containing a 920 g / eq EW perfluorosulfonic acid resin ion-exchange polymer reinforced with one layer of expanded porous ePTFE membrane #1 was prepared using conventional laboratory techniques. First, a water-ethanol-based solution of perfluorosulfonic acid resin (obtained from Asahi Glass Co., Ltd., Japan) with an EW of 920 g / eq was coated onto a moving substrate layer using a roll-transfer method, aiming for a nominal wet coating thickness of 200 microns at a solids concentration of 23%. The substrate layer was a polymer sheet (obtained from Daicel Value Coating Co., Ltd., Japan) containing PET and a protective layer of cyclic olefin copolymer (COC), oriented with the COC side facing up. The laminate was then dried in an oven at 160 °C and annealed at that temperature for 3 minutes to produce a solid coating structure comprising the substrate layer bonded to the polymer layer reinforced with expanded porous polytetrafluoroethylene. The resulting composite electrolyte membrane comprises a substrate layer bonded to an ion-exchange polymer layer, followed by a microporous polytetrafluoroethylene membrane layer with an ion-exchange polymer embedded therein, with a total thickness of 29 microns and a mass of 59 g / m at 50% RH. 2 The resulting composite electrolyte membrane was characterized by having an ion exchange material embedded within the microporous polymer structure, leaving an unoccluded portion of the microporous polymer structure nearest the first surface, and a layer of ion exchange material less than 1 micron thick on the second surface of the microporous polymer structure.

[0157] Example 6 A 25-micron-thick composite electrolyte membrane containing an ion-exchange polymer, perfluorosulfonic acid resin, with an EW of 810 g / eq, reinforced with one layer of expanded porous ePTFE membrane #1 was prepared using conventional laboratory techniques. First, a water-ethanol-based solution of perfluorosulfonic acid resin with an EW of 810 g / eq (obtained from Asahi Glass Co., Ltd., Japan) was coated onto a moving substrate layer using a roll transfer method, aiming for a nominal wet coating thickness of 160 microns at a solids concentration of 23%, and then laminated with ePTFE membrane #1. The substrate layer was a polymer sheet (obtained from Daicel Value Coating Co., Ltd., Japan) containing PET and a protective layer of cyclic olefin copolymer (COC), oriented with the COC side facing up. The laminate was then dried in an oven at 160 °C and annealed at that temperature for 3 minutes to produce a solid coating structure comprising the substrate layer bonded to the polymer layer reinforced with expanded porous polytetrafluoroethylene. The resulting composite electrolyte membrane comprises a substrate layer bonded to an ion-exchange polymer layer, followed by a microporous polytetrafluoroethylene membrane layer with an ion-exchange polymer embedded therein, and has a total thickness of 25 microns and a mass of 52 g / m at 50% RH. 2 The resulting composite electrolyte membrane was characterized by having an ion exchange material embedded within the microporous polymer structure, leaving an unoccluded portion of the microporous polymer structure nearest the first surface, and a layer of ion exchange material less than 1 micron thick on the second surface of the microporous polymer structure.

[0158] Example 7 A 17-micron-thick composite electrolyte membrane containing an ion-exchange polymer, perfluorosulfonic acid resin, with an EW of 720 g / eq, reinforced with two layers of expanded porous ePTFE membrane #5 was prepared using conventional laboratory techniques. First, a water-ethanol-based solution of perfluorosulfonic acid resin with an EW of 720 g / eq (obtained from Asahi Glass Co., Ltd., Japan) was coated onto a moving substrate layer using a slot die method, aiming for a nominal wet coating thickness of 90 microns at a solids concentration of 11%, and then laminated with ePTFE membrane #5. The substrate layer was a polymer sheet (obtained from Daicel Value Coating Co., Ltd., Japan) containing PET and a protective layer of cyclic olefin copolymer (COC), oriented with the COC side facing up. The laminate was then dried in an oven at 160 °C and annealed at that temperature for 1 minute to produce a solid coating structure containing the substrate layer bonded to the polymer layer reinforced with expanded porous polytetrafluoroethylene. The air side of the dried membrane was then coated with the same perfluorosulfonic acid resin at 11% solids using a slot die method to achieve a nominal wet coating thickness of 90 microns, laminated with an ePTFE membrane #5, and dried in an oven at 160°C for 1 minute. The dried membrane was finally annealed at 190°C for 3 minutes. The air side of the dried membrane was then coated with the same perfluorosulfonic acid resin at 4.5% solids using a slot die method to achieve a nominal wet coating thickness of 65 microns and dried in an oven at 160°C for 1 minute. The resulting composite electrolyte membrane comprised a substrate layer bonded to an ion-exchange polymer layer, followed by a microporous polytetrafluoroethylene membrane layer with an ion-exchange polymer embedded therein, followed by an ion-exchange polymer layer, followed by a microporous polytetrafluoroethylene membrane layer with an ion-exchange polymer embedded therein, followed by an ion-exchange layer. The resulting composite membrane had a total thickness of 17 microns and a mass of 29.5 g / m at 50% RH. 2 had a mass / area of

[0159] Example 8 An 85-micron-thick composite electrolyte membrane containing an ion-exchange polymer, perfluorosulfonic acid resin, with an EW of 720 g / eq, reinforced with three layers of expanded porous ePTFE membrane #6 was prepared using conventional laboratory techniques. First, a water-ethanol-based solution of perfluorosulfonic acid resin with an EW of 720 g / eq (obtained from Asahi Glass Co., Ltd., Japan) was coated onto the substrate layer using a drawdown bar coating method, aiming for a nominal wet coating thickness of 200 microns, at a solids concentration of 17%. The substrate layer was then laminated with ePTFE membrane #6. The coating was performed using a drawdown bar with a 5-mil gap. The substrate layer was a polymer sheet (obtained from Daicel Value Coating Co., Ltd., Japan) containing PET and a protective layer of cyclic olefin copolymer (COC), oriented with the COC side facing up. The laminate was then dried in an oven at 125°C and annealed at that temperature for 1 minute to produce a solid coating structure comprising a substrate layer bonded to a polymer layer reinforced with expanded porous polytetrafluoroethylene. The air side of the dried first interlayer was then coated with the same perfluorosulfonic acid resin at 17% solids using the drawdown bar method, targeting a nominal wet coating thickness of 200 microns, with a drawdown bar having a 12.5 mil gap, laminated with ePTFE membrane #6, and dried in an oven at 125°C for 1 minute. The air side of the dried second interlayer was then coated with the same perfluorosulfonic acid resin at 17% solids using the drawdown bar method, targeting a nominal wet coating thickness of 200 microns with a drawdown bar having a 12.5 mil gap, laminated with ePTFE membrane #6, and dried in an oven at 125°C for 1 minute. The air side of the dried third interlayer was then coated with the same perfluorosulfonic acid resin at 17% solids using the drawdown bar method, targeting a nominal wet coating thickness of 105 microns using a drawdown bar with a 6.5 mil gap, and dried in an oven for 1 minute at 125° C. The dried membrane was finally annealed at 165° C. for 3 minutes.The resulting composite electrolyte membrane comprises a substrate layer bonded to an ion exchange polymer layer, followed by a microporous polytetrafluoroethylene membrane layer with an ion exchange polymer embedded therein, followed by an ion exchange polymer layer, followed by a microporous polytetrafluoroethylene membrane layer with an ion exchange polymer embedded therein, followed by an ion exchange layer, followed by a microporous polytetrafluoroethylene membrane layer with an ion exchange polymer embedded therein, followed by an ion exchange layer, and has a total thickness of 85 microns and 165 g / m at 50% RH. 2 had a mass / area of Comparative Example 1 Comparative Example 1 is a commercially available electrolyte membrane, Nafion™ NR212, obtained from Chemours Corporation, cast without reinforcement (ie, without a layer containing a microporous polymer structure).

[0160] Comparative Example 2 A 40-micron-thick composite electrolyte membrane containing a perfluorosulfonic acid resin ion-exchange polymer with an EW of 810 g / mol acid equivalent (EW) reinforced with one layer of expanded porous ePTFE comparative membrane #2 was prepared using conventional laboratory techniques. First, a water-ethanol-based solution of perfluorosulfonic acid resin with an EW of 810 g / eq (obtained from Asahi Glass Co., Ltd., Japan) was coated onto a moving substrate layer using a roll transfer method, aiming for a nominal wet coating thickness of 180 microns at a solids concentration of 27%. The substrate layer was a polymer sheet (obtained from Daicel Value Coating Co., Ltd., Japan) containing PET and a protective layer of cyclic olefin copolymer (COC), oriented with the COC side facing up. The laminate was then dried in an oven at 160 °C and annealed at that temperature for 3 minutes to produce a solid coating structure containing the carrier substrate bonded to the polymer layer reinforced with expanded porous polytetrafluoroethylene. The resulting composite electrolyte membrane comprises a substrate layer bonded to an ion-exchange polymer layer, followed by a microporous polytetrafluoroethylene membrane layer with an ion-exchange polymer embedded therein, and has a total thickness of 40 microns and a mass of 79 g / m at 50% RH. 2The resulting composite electrolyte membrane was characterized by having an ion exchange material embedded within the microporous polymer structure, leaving the portion of the microporous polymer structure closest to the first surface unblocked, and a layer of ion exchange material less than 1 micron thick on the second surface of the microporous polymer structure.

[0161] Discussion of results The composite electrolyte membrane was characterized by carrying out the elastic modulus test and swelling ratio test described above. The elastic modulus of the composite electrolyte membrane of Example 1 in the longitudinal (machine) direction was 732 MPa, and the elastic modulus in the transverse direction was 858 MPa. The swelling ratio of the composite electrolyte membrane of Example 1 in the longitudinal (machine) direction was 5.2%, and the swelling ratio in the transverse direction was 2.1%.

[0162] As can be seen from a comparison with Comparative Example 2, the composite electrolyte membrane of the present invention has a high elastic modulus and contains high-elastic modulus ePTFE. The composite electrolyte membrane of the present invention exhibits balanced ePTFE elastic modulus in either lateral direction (i.e., MD / TD), and has reduced swelling ratios in the MD and TD directions using amounts of components (e.g., ionomer mass per area based on the total mass of ionomer in the composite electrolyte membrane per area of ​​the composite electrolyte membrane, ePTFE mass per area based on the total mass of ionomer in the composite electrolyte membrane per area of ​​the composite electrolyte membrane, ePTFE vol% based on the total volume of ePTFE present in the volume of the composite membrane) and ionomer type (EW) similar to those of Comparative Example 2.

[0163] The test procedures and measurement protocols were carried out as described above to determine the properties of the composite electrolyte membrane, such as ultimate tensile strength in the MD and TD, modulus, or swelling ratio, as well as the properties of the porous layer present in the composite electrolyte membrane. The properties of the porous layer were measured for the porous layer in its original state (i.e., before the ion exchange material was embedded in the porous layer).

[0164] Table 2 (FIG. 10) shows the properties of the porous layers used in the composite electrolyte membranes having the properties shown in Table 1 (FIG. 9).

Claims

1. A composite electrolyte membrane, comprising: a) at least one porous layer comprising a microporous polymer structure; and b) an ion exchange material at least partially embedded within said microporous polymer structure, rendering said microporous polymer structure occlusive; Including, the composite electrolyte membrane has a modulus of elasticity in a first axis direction and a modulus of elasticity in a second axis direction of the composite electrolyte membrane of at least about 450 MPa at 50% relative humidity when measured according to the Tensile Strength Test described herein; the at least one porous layer has an elastic strength in a first axis and an elastic strength in a second axis of the porous layer of at least about 30 N / m when measured according to the Tensile Strength Test described herein; a composite electrolyte membrane, wherein the absolute ratio of the elastic modulus of the composite electrolyte membrane in a first axial direction of the composite electrolyte membrane to the elastic modulus of the composite electrolyte membrane in a second axial direction of the composite electrolyte membrane is from about 0.45 to about 2.

20.

2. 2. The composite electrolyte membrane of claim 1, wherein an absolute ratio of an elastic strength of the at least one porous layer in a first axial direction of the porous layer to an elastic strength of the at least one porous layer in a second axial direction of the porous layer is from about 0.45 to about 2.

20.

3. 3. The composite electrolyte membrane according to claim 1 or 2, wherein the absolute ratio of the elastic modulus in the first axial direction to the second axial direction of the composite electrolyte membrane is from about 0.45 to about 2.10, or from about 0.50 to about 2.00, or from about 0.80 to about 1.20, or from about 0.80 to about 1.00, or from about 0.80 to about 0.90, or from about 0.70 to about 1.30, or from about 0.60 to about 1.80, or from about 0.90 to about 1.20, or from about 1.00 to about 1.20, or from about 1.10 to about 1.

20.

4. 10. The composite electrolyte membrane of any one of the preceding claims, wherein the absolute ratio of the elastic strengths in the first axial direction and the second axial direction of the at least one porous layer is from about 0.45 to about 2.20, or from about 0.45 to about 2.10, or from about 0.50 to about 2.00, or from about 0.80 to about 1.20, or from about 0.80 to about 1.00, or from about 0.80 to about 0.90, or from about 0.70 to about 1.30, or from about 0.60 to about 1.80, or from about 0.90 to about 1.20, or from about 1.00 to about 1.20, or from about 1.10 to about 1.

20.

5. the composite electrolyte membrane has an ultimate tensile strength in a first axis direction of the composite electrolyte membrane of at least about 55 MPa when measured according to the Tensile Strength Test described herein; and / or 10. The composite electrolyte membrane of any one of the preceding claims, wherein the composite electrolyte membrane has an ultimate tensile strength in the second axis direction of the composite electrolyte membrane of at least about 60 MPa when measured according to the Tensile Strength Test described herein.

6. the total porous layer ultimate web tensile strength in the first axial direction of the porous layer is at least about 800 N / m when measured according to the Tensile Strength Test described herein; and / or 10. The composite electrolyte membrane of any one of the preceding claims, wherein the porous layers have a total porous layer ultimate web tensile strength in the second axial direction of at least about 800 N / m when measured according to the Tensile Strength Test described herein.

7. the total porous layer elastic strength in the first axis direction of the porous layer is at least about 30 N / m when measured according to the Tensile Strength Test described herein; and / or 10. The composite electrolyte membrane of any one of the preceding claims, wherein the porous layer has a total porous layer elastic strength in the second axial direction of at least about 30 N / m when measured according to the Tensile Strength Test described herein.

8. a swelling ratio of the composite electrolyte membrane in a first direction is about 6% or less when measured using the Swelling Test described herein at about 100° C. and a relative humidity of about 100%, and optionally a swelling ratio of the composite electrolyte membrane in a first direction is about 5.2% when measured using the Swelling Test described herein at about 100° C. and a relative humidity of 100%, and / or 10. The composite electrolyte membrane of claim 1, wherein the swelling ratio of the composite electrolyte membrane in the second direction is about 6% or less, or about 7% or less, when measured by the Swelling Test described herein at 100°C at about 100% relative humidity, and optionally the swelling ratio of the composite electrolyte membrane in the second direction is about 7%, or about 5%, or about 2%, when measured by the Swelling Test described herein at 100°C at about 100% relative humidity.

9. The microporous polymer structure of the at least one porous layer comprises a fluorinated polymer, and optionally 10. The composite electrolyte membrane of any one of the preceding claims, wherein at least one of the fluorinated polymers is polytetrafluoroethylene (PTFE), poly(ethylene-co-tetrafluoroethylene) (EPTFE), expanded polytetrafluoroethylene (ePTFE), polyvinylidene fluoride (PVDF), expanded polyvinylidene fluoride (ePVDF), expanded poly(ethylene-co-tetrafluoroethylene) (eEPTFE), or mixtures thereof.

10. the fluorinated polymer is perfluorinated expanded polytetrafluoroethylene (ePTFE); In some cases, the composite electrolyte membrane has a surface area of ​​about 5.5 g m based on the total area of ​​the composite electrolyte membrane. －２ ~Approx. 80g・m －２ , or about 8 g m －２ ~Approx. 50g・m －２ , or about 20 g m －２ ~Approx. 40g・m －２ , or about 31 g m based on the total area of ​​the composite electrolyte membrane －２ The composite electrolyte membrane according to claim 9, having a total content (mass per unit area) of the microporous polymer structure selected from the group consisting of:

11. 10. The composite electrolyte membrane according to claim 1, wherein the microporous polymer structure of the at least one porous layer comprises a hydrocarbon polymer, and optionally the hydrocarbon polymer comprises polyethylene, polypropylene, polycarbonate, polystyrene, or a mixture thereof.

12. the composite electrolyte membrane has a total content of microporous polymer structures of about 15 vol. % to about 70 vol. %, based on the total volume of the composite electrolyte membrane, and optionally, the composite electrolyte membrane has a total microporous polymer content of about 42 vol. %, based on the total volume of the composite electrolyte membrane. the composite electrolyte membrane has a thickness of about 10 μm to about 115 μm when measured at 25° C. and 50% relative humidity in the Thickness Measurement Test described herein, and optionally the composite electrolyte membrane has a thickness of about 40 μm when measured at 25° C. and 50% relative humidity in the Thickness Measurement Test described herein. the at least one porous layer has a thickness of from about 0.1 μm to about 230 μm when measured at 25° C. at 50% relative humidity in the Thickness Measurement Test described herein, and optionally the at least one porous layer has a thickness of about 85 μm when measured at 25° C. at 50% relative humidity in the Thickness Measurement Test described herein.

10. The composite electrolyte membrane according to claim 9, wherein the first and second electrodes are oriented in a direction perpendicular to the surface of the electrolyte membrane.

13. the at least one porous layer having a first surface and a second surface; and an ion exchange material forms a layer on at least one of the first surface or the second surface of the at least one porous layer; or the at least one porous layer having a first surface and a second surface; and an ion exchange material forms a layer on both the first surface and the second surface of the at least one porous layer; Optionally, the ion exchange material of the layer of ion exchange material formed on the first surface of the at least one porous layer is different from the ion exchange material of the layer of ion exchange material formed on the second surface of the at least one porous layer, or the ion exchange material of the layer of ion exchange material formed on the first surface of the at least one porous layer is the same as the ion exchange material of the layer of ion exchange material formed on the second surface of the at least one porous layer.

14. The ion exchange material comprises at least one ionomer, and optionally The ion exchange material comprises at least two ionomers. the at least one ionomer comprises a proton conducting polymer, and optionally the proton conducting polymer comprises a hydrocarbon ionomer; the proton conducting polymer comprises a perfluorinated ionomer; the proton conducting polymer comprises perfluorosulfonic acid; 10. The composite electrolyte membrane of claim 9, wherein:

15. the at least one ionomer has a density of about 1.9 g / cc or greater at 25° C. and 0% relative humidity; The at least one ionomer has a SO 2 content of about 500 g / eq. ３ － ~ about 2000 g / eq SO ３ － and optionally the ion exchange material has a total equivalent weight (EW) of about 900 g / eq SO ３ － or the ion exchange material has an equivalent weight of about 1800 g / eq SO ３ － having an equivalent of The composite electrolyte membrane according to claim 14, which is at least one of the following:

16. 10. The composite electrolyte membrane of any one of the preceding claims, wherein the composite electrolyte membrane has an elastic modulus in a first axial direction of the composite electrolyte membrane and an elastic modulus in a second axial direction of the composite electrolyte membrane, when measured according to the Tensile Strength Test described herein, independently selected from about 450 MPa to about 2300 MPa at about 50% relative humidity, or about 600 MPa to about 1500 MPa at about 50% relative humidity, or about 700 MPa to about 800 MPa at about 50% relative humidity.

17. 10. The composite electrolyte membrane of any one of the preceding claims, wherein the composite electrolyte membrane swells preferentially in a third axial direction of the composite electrolyte membrane, and optionally the composite electrolyte membrane has a swelling degree of about 5% to about 150% in the third axial direction of the composite electrolyte membrane at about 100% RH and 100°C when measured according to the Swelling Test described herein.

18. 1. A composite electrolyte membrane-electrode assembly for an electrochemical device, comprising: at least one electrode; and The composite electrolyte membrane according to any one of claims 1 to 17, which is in contact with the at least one electrode. and optionally, the composite electrolyte membrane is attached to the at least one electrode.

19. The composite electrolyte membrane-electrode assembly comprises: Electrodes, and The composite electrolyte membrane according to any one of claims 1 to 17, Including, the electrodes and the composite electrolyte membrane are in contact with each other, Depending on the situation, the composite electrolyte membrane has a first surface and a second surface, and the electrode is a first electrode layer attached to the first surface of the composite electrolyte membrane, and the membrane electrode assembly further includes a second electrode layer attached to the second surface of the composite electrolyte membrane. the electrode, or one or both of the first electrode layer and the second electrode layer, is a porous layer; the electrode, or one or both of the first electrode layer and the second electrode layer, is selected from felt, paper, or woven materials; 19. The composite electrolyte membrane-electrode assembly according to claim 18, which is a redox flow battery membrane-electrode assembly, wherein the composite electrolyte membrane-electrode assembly is at least any one of the following:

20. The composite electrolyte membrane-electrode assembly comprises: a) at least one electrode; and b) the composite electrolyte membrane according to any one of claims 1 to 17; Including, the at least one electrode is in contact with the composite electrolyte membrane; Depending on the situation, 19. The composite electrolyte membrane-electrode assembly of claim 18, which is an electrolyzer membrane-electrode assembly, further comprising a fluid diffusion layer, and optionally, the fluid diffusion layer is selected from felt, paper or woven material, carbon / carbon-based diffusion layer, titanium porous sintered powder mesh / plate / fiber / felt, stainless steel mesh, or a mixture thereof.

21. a) a first electrode layer and a second electrode layer; b) the composite electrolyte membrane according to any one of claims 1 to 17, wherein the first electrode layer and the second electrode layer are disposed on opposite surfaces of the composite electrolyte membrane; and c) a fluid diffusion layer disposed on the first electrode layer and the second electrode layer; The composite electrolyte membrane-electrode assembly of claim 20, comprising:

22. A redox flow battery comprising the composite electrolyte membrane according to any one of claims 1 to 17 or the composite electrolyte membrane-electrode assembly according to any one of claims 18 to 19.

23. First end plate, a first current collecting plate, A plurality of the redox flow battery of claim 22 connected in series. a second current collector; and A second end plate, A redox flow battery stack comprising: the plurality of redox flow batteries are disposed between the first current collector plate and the second current collector plate; and the first end plate is disposed adjacent to the first current collector plate, and the second end plate is disposed adjacent to the second current collector plate; Optionally, the redox flow battery stack includes a housing.

24. An electrolytic cell comprising the composite electrolyte membrane according to any one of claims 1 to 17 or the electrolytic cell composite electrolyte membrane-electrode assembly according to any one of claims 20 or 21.

25. A method for producing a composite electrolyte membrane according to any one of claims 1 to 17, a) providing a support layer for the composite electrolyte membrane; b) disposing a layer of a first liquid ionomer composition on said support layer; c) disposing a porous layer comprising a microporous polymer structure on the layer of the first liquid ionomer composition, and at least partially embedding the ion exchange material of the first liquid ionomer composition within the microporous polymer structure of the porous layer to render the microporous polymer structure occlusive, and optionally applying pressure to the porous layer to laminate the composite electrolyte membrane; and d) drying the composite to remove the liquid component; and optionally, after step c) or d), the method comprises: e) disposing a layer of a second liquid ionomer composition on a surface of the porous layer opposite the surface on which the first liquid ionomer composition is present; and f) drying the composite to remove the liquid component; The method further comprises the steps of A method wherein the drying step d) is optional when steps e) and f) are present.

26. A method for producing a composite electrolyte membrane according to any one of claims 1 to 17, a) providing a support layer for the composite electrolyte membrane; b) disposing a layer of a first liquid ionomer composition on said support layer; c) providing at least one porous layer comprising a microporous polymer structure and having a first surface and a second surface, and disposing the first surface of the at least one porous layer over the layer of the first liquid ionomer composition; d) disposing a layer of the first liquid ionomer composition on the second surface of the at least one porous layer so as to be completely absorbed into the microporous polymer structure and render the microporous polymer structure occlusive; and e) drying the composite to remove the liquid component; Including, Optionally, the method further comprises: f) disposing a layer of a second liquid ionomer composition over the layer of the first liquid ionomer composition on the second surface of the at least one porous layer; and g) drying the composite to remove the liquid component; The method further comprises the step of:

27. A method for producing a composite electrolyte membrane according to any one of claims 1 to 17, comprising: a) providing a support layer for the composite electrolyte membrane; b) disposing a layer of a first liquid ionomer composition on said support layer; c) providing a porous layer comprising a microporous polymer structure and having a first surface and a second surface; d) disposing the first surface of the porous layer over a layer of the first liquid ionomer composition, causing the ion exchange material of the first liquid ionomer composition to be at least partially embedded within the microporous polymer structure, thereby rendering the microporous polymer structure occlusive; e) disposing a layer of a second liquid ionomer composition on the second surface of the porous layer; and f) drying the composite to remove the liquid component; A method comprising:

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