Porous transport membrane and manufacturing method thereof

Abstract

The present invention provides a porous transport membrane and a manufacturing method thereof. The porous transport membrane has an excellent ability to transport gaseous and liquid substances and a large contact area with a catalyst layer, and thus can greatly improve performance when applied to an anion exchange membrane water electrolysis system.

Description

Porous transport membrane and method for manufacturing the same

[0001] Cross-citation with related application(s)

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2024-0041898, filed March 27, 2024, and Korean Patent Application No. 10-2025-0038843, filed March 26, 2025, the entire contents of which are incorporated herein by reference.

[0003] The present invention relates to a porous transport membrane having excellent material transfer capability and a large contact area with a catalyst layer, and a method for manufacturing the same.

[0004]

[0005] The importance of environmentally friendly hydrogen production technology is being highlighted due to fossil fuel depletion and environmental pollution issues.

[0006] Accordingly, active research is being conducted on water electrolysis technologies using electrolysis. Representative water electrolysis technologies include alkaline water electrolysis (AWE), proton exchange membrane water electrolysis (PEMWE), and anion exchange membrane water electrolysis (AEMWE).

[0007] Alkaline water electrolysis primarily utilizes nickel-based oxides and cobalt-based oxides as catalysts for the reduction and oxidation electrodes, and uses an alkaline aqueous solution such as KOH as the electrolyte. It has the advantages of not requiring precious metal catalysts and operating at relatively low temperatures. However, it suffers from low hydrogen production rates and the large size of the design system for hydrogen production. Furthermore, the liquid alkaline electrolyte is prone to leakage, which increases resistance, reduces current density, and ultimately reduces electrolysis efficiency.

[0008] Meanwhile, cation exchange membrane electrolysis (CEM) is a water electrolysis system that uses a solid electrolyte membrane, such as Nafion, instead of a liquid electrolyte. Because the volume occupied by the solid electrolyte membrane is smaller than that of a liquid electrolyte, the system can be reduced in size and provide high current density. However, because it operates in an acidic environment, platinum-based catalysts, such as IrO2 and Pt, that can withstand the strong corrosiveness of acidic environments are required for the reduction and oxidation electrode catalyst materials. However, the use of these expensive PEM catalysts increases the cost of hydrogen production, posing a significant obstacle to the commercialization of CEM.

[0009] In contrast, anion exchange membrane electrolysis (ANEM) utilizes the advantages of existing systems while overcoming their shortcomings. Because anion exchange membrane electrolysis operates in an alkaline environment, it can utilize non-platinum metals as catalysts, allowing for a compact system with relatively high energy density. However, non-platinum metal catalysts exhibit lower catalytic activity than platinum metal catalysts, resulting in lower electrolysis efficiency.

[0010] An anion exchange membrane electrolysis system comprises an anion exchange membrane electrolysis stack comprising a plurality of electrolysis cells, and peripheral devices for driving the same. In addition, the electrolysis cell comprises a membrane-electrode assembly (MEA) including an electrolyte membrane, an oxidation electrode (anode), and a reduction electrode (cathode), and optionally further comprises a porous gas diffusion layer (GDL) for the reduction electrode, a porous transport layer (PTL) for the oxidation electrode, a separator for the reduction electrode, and a separator for the oxidation electrode. Water introduced through a passageway of the separator for the oxidation electrode is supplied to the oxidation electrode through the PTL, and hydrogen gas generated at the reduction electrode is discharged through the GDL and the passageway of the separator for the reduction electrode. The electrochemical reaction of this water electrolysis cell is such that water supplied to the oxidation electrode is separated into hydrogen ions (H+) and electrons along with oxygen gas through the oxygen evolution reaction (OER), and then moves to the reduction electrode through the electrolyte membrane and external circuit, generating hydrogen gas through the hydrogen evolution reaction.

[0011] The above PTL serves to evenly distribute and diffuse the reactant, water, across the surface of the oxidation electrode and to discharge oxygen generated at the oxidation electrode to the outside through a separator. It also collects and transmits electrons generated by the electrochemical reaction.

[0012] Conventionally, PTLs have been used as fiber-sintered PTLs, which are manufactured by laminating and then sintering fibrous metals, or as powder-sintered PTLs, which are manufactured by depositing or coating powdered metals and then sintering them. An example of a felt-type PTL is titanium felt, which is manufactured by non-uniformly laminating titanium wires and then rolling and sintering them. Titanium felt PTLs have a small contact area with the catalyst layer, so their electrical conductivity is low, and the pore size is relatively large and non-uniform, so water distribution and diffusion and the removal of generated oxygen are not easy. In addition, due to the shape characteristics, the surface roughness is high, which can cause damage to the electrolyte membrane, resulting in an electrical short circuit, or there is a risk of explosion due to cross-migration of oxygen / hydrogen.

[0013] Meanwhile, in the case of the powder sintered body type, the contact area with the catalyst layer is large, so the performance is relatively excellent, and the surface roughness is low, so the risk of damaging the electrolyte membrane is relatively low, but compared to the fiber sintered body, there was a disadvantage in that it was difficult to simultaneously increase the mechanical strength to maintain a high surface pressure and secure structural stability, and the porosity to facilitate smooth diffusion / distribution of reactants and discharge of products.

[0014] Recently, research has been conducted on using nickel foam or mesh alone or in combination with functional coating layers of other materials to form a laminate. However, when nickel foam or mesh is used alone, its wide pores and narrow contact area with the catalyst layer result in low performance. Furthermore, the rough surface of the nickel foam can cause cracks in the catalyst layer during the rolling process, resulting in catalyst delamination and subsequent deterioration of cell performance. Furthermore, the delamination of the catalyst layer can lead to reduced durability.

[0015] Although there is some performance improvement effect when used in combination with a functional coating layer, it is still insufficient in terms of material transfer ability and improvement of contact area with the catalyst layer, and further research is needed.

[0016]

[0017] The present invention provides a porous transport membrane having excellent transport capability for gaseous and liquid substances and a large contact area with a catalyst layer, and a method for manufacturing the same.

[0018]

[0019] According to the present invention, a porous transport membrane (PTL) is provided, which comprises nickel foam and has a contact area ratio of 27.00% to 92.00% according to the following mathematical formula 1:

[0020] [Mathematical Formula 1]

[0021] Contact area ratio (%) = (B / A) x 100

[0022] In the above mathematical formula 1,

[0023] A is the total surface area (m) of the porous transport membrane on the side where the porous transport membrane is in contact with the electrode. 2 ) and,

[0024] B is the actual contact area (m) of the porous transport membrane and the electrode. 2 )am.

[0025] In addition, according to the present invention, a method for manufacturing a porous transport membrane is provided, including a step of manufacturing a laminate by laminating three nickel foams; and a step of compressing the laminate, wherein, when manufacturing the laminate, nickel foams are laminated so that the pore size of each layer satisfies any one of the following conditions (i) to (iii) when dividing the upper layer, middle layer, and lower layer according to the position in the thickness direction of the laminate:

[0026] (i) Upper layer < Middle layer ≤ Lower layer

[0027] (ii) Upper layer ≥ Middle layer > Lower layer

[0028] (iii) Upper layer = Middle layer = Lower layer

[0029] Furthermore, according to the present invention, an anion exchange membrane electrolysis system is provided, which includes an oxidation electrode (anode), a reduction electrode (cathode), and an anion exchange membrane interposed between the oxidation electrode and the reduction electrode, and further includes the porous transport membrane on the side opposite to the side of the oxidation electrode that is in contact with the anion exchange membrane.

[0030]

[0031] The porous transport membrane according to the present invention has excellent transport capacity for gaseous and liquid substances and has a large contact area with a catalyst layer, so that when applied to an anion exchange membrane electrolysis system, performance can be greatly improved.

[0032]

[0033] Figure 1 is a schematic diagram schematically showing the structure of an anion exchange membrane electrolysis system according to the present invention.

[0034] Figure 2a is the result of simulating the cross-section (xy cross-section) of the porous transport membrane (PTL) of Comparative Example 2 in the thickness direction using Geodict.

[0035] Figure 2b is the result of simulating the lateral cross-section (xy cross-section) of the PTL of Comparative Example 6 when cut in the thickness direction using Geodict.

[0036] Figure 3a is the result of simulating the lateral cross-section (yz cross-section) of the PTL of Comparative Example 6 when cut in the thickness direction using Geodict.

[0037] Figure 3b is the result of simulating the lateral cross-section (yz cross-section) of the PTL of Comparative Example 9 when cut in the thickness direction using Geodict.

[0038] Figure 4 is a graph showing the results of the evaluation of the bending rate for the PTL of Example 2, Comparative Example 2, Comparative Example 3, and Comparative Example 6.

[0039]

[0040] In the present invention, terms such as first, second, etc. are used to describe various components, and the terms are used only for the purpose of distinguishing one component from another.

[0041] Additionally, the terms used herein are merely used to describe exemplary embodiments and are not intended to limit the present invention.

[0042] Singular expressions include plural expressions unless the context clearly indicates otherwise.

[0043] In this specification, the terms “comprise,” “include,” or “have” are intended to describe a feature, number, step, component, or combination thereof implemented, but do not exclude the possibility of one or more other features, numbers, steps, components, combinations, or additions thereof.

[0044] Additionally, in this specification, when each layer or element is referred to as being formed “on” or “over” each layer or element, it means that each layer or element is formed directly on each layer or element, or that other layers or elements may be additionally formed between each layer, on the object, or on the substrate.

[0045] The present invention is susceptible to various modifications and takes various forms. Specific embodiments are illustrated and described in detail below. However, this does not limit the invention to a specific disclosed form, but rather encompasses all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention.

[0046] Hereinafter, the present invention will be described in detail.

[0047]

[0048] According to the present invention, a porous transport membrane (PTL) is provided, which comprises nickel foam and has a contact area ratio of 27.00% to 92.00% calculated according to the following mathematical formula 1:

[0049] [Mathematical Formula 1]

[0050] Contact area ratio (%) = (B / A) x 100

[0051] In the above mathematical formula 1,

[0052] A is the total surface area (m) of the porous transport membrane on the side where the porous transport membrane is in contact with the electrode. 2 ) and,

[0053] B is the actual contact area (m) of the porous transport membrane and the electrode. 2 )am.

[0054]

[0055] As the contact area between the PTL and the electrode of the anion exchange membrane electrolysis system, more specifically the catalyst layer (CL), increases, the contact resistance (Ohmic Resistance) decreases, which can result in improved cell performance. In addition, since the reaction site is widened and the reaction is possible in a large area, the overpotential can be reduced. However, if the contact area is too wide, specifically, if it exceeds 92.00%, the pore ratio, which serves as the transport channel for the reactants, is low, making it difficult for the reactants to be transferred to the electrode surface, resulting in mass transfer overpotential, which in turn deteriorates the cell performance. On the other hand, mass transfer overpotential refers to the phenomenon where, when the transport of reactants to the electrode surface by convection becomes difficult, a concentration difference occurs as H2O is consumed by the current, resulting in a decrease in the concentration of the reactants, which in turn deteriorates the cell performance.

[0056] Additionally, if the contact area is too narrow, specifically less than 27.00%, the contact resistance increases, resulting in a deterioration in cell performance.

[0057] The PTL according to the present invention can exhibit superior improvement effects in terms of initial voltage and durability when applied to an anion exchange membrane electrolysis system by satisfying the above-mentioned contact area ratio range. Specifically, the contact area ratio of the PTL according to the present invention is 27.00% or more, or 27.50% or more, or 27.70% or more, or 30.00% or more, and 92.00% or less, or 70.00% or less, or 50.00% or less, or 45.00% or less, or 43.00% or less, or 42.95% or less, or 40.00% or less.

[0058] Meanwhile, the contact area ratio in the present invention is calculated by measuring the actual surface area of ​​the porous transport membrane on the surface in contact with the electrode through a structural analysis simulation (Geodict) after micro-CT (micro-computed tomography), and then calculating the total surface area of ​​the porous transport membrane on the surface in contact with the electrode and the actual contact area of ​​the porous transport membrane and the electrode using these. The specific measurement method and conditions are as described in the experimental example below.

[0059] In addition, the PTL includes a plurality of pores, and the pore size D50 is 60.00 nm to 100.00 nm. More specifically, it is 60.00 nm or more, or 62.00 nm or more, or 62.50 nm or more, or 70.00 nm or more, and 100.00 nm or less, or 90.00 nm or less, or 85.00 nm or less, or 80.00 nm or less.

[0060] In addition, in the above PTL, the pore size D10 is 25.00 nm to 35.00 nm. More specifically, the pore size D10 is 25.00 nm or more, or 25.50 nm or more, or 25.80 nm or more, or 27.00 nm or more, and 35.00 nm or less, or 34.00 nm or less, or 33.50 nm or less, or 33.00 nm or less.

[0061] In addition, in the above PTL, the pore size D90 is 110.00 nm to 160.00 nm. More specifically, the pore size D90 is 110.00 nm or more, or 111.00 nm or more, or 111.50 nm or more, or 120.00 nm or more, or 140.00 nm or more, and 160.00 nm or less, or 155.00 nm or less, or 154.00 nm or less, or 150.00 nm or less.

[0062] Pore ​​size affects contact resistance and mass transfer capability. The PTL according to the present invention can exhibit reduced contact resistance and mass transfer resistance by satisfying the above-described pore size conditions.

[0063] Meanwhile, in the present invention, the pore size D50 refers to the pore size at the point where 50% of the cumulative pore volume distribution according to pore size is measured through a structural analysis simulation of a porous transport membrane. In addition, the pore sizes D10 and D90 refer to the pore sizes at the points where 10% and 90% of the cumulative pore volume distribution according to pore size is measured using the same method as above. The specific measurement method and conditions are as described in the experimental examples below.

[0064] In addition, the above PTL is a porosity calculated according to the following mathematical formula 2 ( ) is between 30.00% and 70.00%:

[0065] [Equation 2]

[0066]

[0067] In the above mathematical expression 2,

[0068] is the porosity (%) of the porous transport membrane,

[0069] is the density of the porous transport membrane (g / cm 3), and is calculated by dividing the mass of the porous transport membrane by its volume according to the Archimedes method.

[0070] is the density of Ni (g / cm 3 ).

[0071] In PTL, as the porosity increases, the curvature decreases and the transmittance increases. As a result, the reactant (OH - ) and product (bubble; O 2 ) can move smoothly. However, if the porosity is too high, the effect may be reduced due to (increased contact resistance caused by decreased contact area). Since the PTL according to the present invention has a porosity in the above range, the material movement is fast, and as a result, the cell performance can be further improved when applied to an anion exchange membrane electrolysis system. More specifically, the porosity of the PTL may be 30.00% or more, or 35.00% or more, or 39.00% or more, or 39.45% or more, or 40.00% or more, or 50.00% or more, and 70.00% or less, or 65.00% or less, or 64.00% or less, or 63.85% or less, or 60.00% or less.

[0072] In addition, the PTL may have a geometric tortuosity (τ) of 2.00 to 5.00 according to the following mathematical formula 3, and the tortuosity of the PTL may be 2.00 or more, or 2.50 or more, or 2.90 or more, or 2.95 or more, or 3.00 or more, and 5.00 or less, or 4.00 or less, or 3.50 or less, or 3.30 or less, or 3.25 or less, or 3.22 or less in terms of the improvement effect according to the control of the tortuosity, specifically, the reactants and products may move quickly and the cell performance may be further improved:

[0073] [Equation 3]

[0074] τ=Le / Ls

[0075] In the above mathematical formula 3,

[0076] Ls is the thickness of the porous transport membrane (PTL), which means the length of the porous transport membrane in the direction in which the substance moves toward the electrode in contact with the porous transport membrane when the porous transport membrane is applied to the anion exchange membrane.

[0077] Le is the average travel distance of a material through the thickness direction of a porous transport membrane, which can be measured and simulated using a porosity analyzer and Geodict.

[0078] In the present invention, the curvature of the PTL is calculated by taking a real photograph of the PTL using Micro CT, implementing a 3D model, conducting a simulation using Geodict, a structural analysis tool, and using the results, according to the mathematical expression 3 above.

[0079] Specific measurement methods and conditions are described in detail in the experimental examples below.

[0080] Meanwhile, the PTL according to the present invention is manufactured by laminating three or more Ni foams and then compressing them, but the manufactured PTL has a single-layer structure without an interlayer interface.

[0081] In the case of a typical laminate, as the number of laminates increases and the compression force increases, the durability of the manufactured laminate improves, but the increase in pressure loss reduces the permeability, making it difficult for substances to move smoothly, resulting in a decrease in cell performance.

[0082] In this regard, since the PTL of the present invention has a single layer structure and has the above-mentioned pore size and distribution, it can exhibit improved permeability while maintaining excellent durability.

[0083] In addition, the PTL has a thickness of 300 μm to 400 μm. If the thickness of the PTL is too thick, the transmittance may decrease, and if the thickness is too thin, the durability may decrease. In this regard, the PTL according to the present invention has a thickness within the above range, so it can exhibit sufficient durability without decreasing the transmittance. More specifically, the thickness of the PTL may be 300 μm or more, or 320 μm or more, or 340 μm or more, and 400 μm or less, or 380 μm or less, or 360 μm or less.

[0084] Also, the above PTL is 4.00 xe 6 S / m or higher, more specifically 4.10 xe 6 S / m or higher, or 4.12 xe 6 S / m or higher, or 4.14 xe 6 S / m or higher, or 4.50 xe 6 S / m or higher, or 5.00 xe 6 S / m or higher, or 5.30 xe 6 S / m or higher, or 8.00 xe 6 S / m or higher, or 8.10 xe 6 S / m or higher, or 8.15 xe 6 It exhibits high electrical conductivity of S / m or more. The upper limit of electrical conductivity is not particularly limited, but for example, 10.00 xe 6 S / m or less, or 9.00 xe 6 S / m or less, or 8.50 xe 6 S / m or less, or 8.20 xe 6 It may be less than S / m.

[0085] In the present invention, as the number of Ni foam layers increases and the compression force increases during the manufacture of the PTL, the ohmic resistance of the manufactured PTL improves, resulting in a higher electrical conductivity.

[0086] The above PTL may be manufactured by a manufacturing method including, for example, a step of manufacturing a laminate by laminating three nickel foams; and a step of compressing the laminate, wherein, when manufacturing the laminate, nickel foams are laminated so that the pore size of each layer satisfies any one of the following conditions (i) to (iii) when dividing the upper layer, middle layer, and lower layer according to the position in the thickness direction of the laminate:

[0087] (i) Upper layer < Middle layer ≤ Lower layer

[0088] (ii) Upper layer ≥ Middle layer > Lower layer

[0089] (iii) Upper layer = Middle layer = Lower layer

[0090] Accordingly, according to the present invention, a method for manufacturing the above PTL is provided.

[0091] When manufacturing a PTL by laminating multiple nickel foams, the contact area ratio of the PTL may vary depending on the number of Ni foam laminates, the compression thickness of the Ni foam laminates, and the ppi value of the Ni foam being pressed. In the present invention, a PTL satisfying the contact area ratio described above was manufactured by the above-described manufacturing method.

[0092] Specifically, a laminate can be manufactured by stacking three nickel foams according to the ppi value of the nickel foam, and pressing the laminate to a thickness of 300 µm to 400 µm.

[0093] For example, when three nickel foams are laminated, the nickel foam on the side in contact with the electrode is referred to as the upper layer of the PTL, the side opposite to the side in contact with the electrode is referred to as the lower layer, and the area between the upper and lower layers is referred to as the intermediate layer, the pore sizes within the nickel foams may be the same or different from the upper layer to the lower layer. In addition, when the pore sizes within the nickel foams of each layer are different, for example, the pore sizes within the nickel foams may have a decreasing gradient from the upper layer to the lower layer, or an increasing gradient. In another example, the pore sizes within the nickel foams may increase or be the same from the upper layer to the intermediate layer, and the pore sizes within the nickel foams may increase from the intermediate layer to the lower layer. In yet another example, the pore sizes within the nickel foams may decrease from the upper layer to the intermediate layer, and the pore sizes within the nickel foams may decrease or be the same from the intermediate layer to the lower layer.

[0094] The nickel foams forming the above laminate may each independently have a thickness of 50 μm to 200 μm.

[0095] Furthermore, by controlling the nickel thickness based on the pore size within the nickel foam, material transport through the pore channels within the manufactured PTL can be facilitated and the transport speed can be further improved. Specifically, the smaller the pore size of the nickel foam, the thinner the nickel foam used.

[0096] In addition, when forming the laminate, the pore size of the nickel foam forming the intermediate layer may be 90 ppi to 130 ppi, and the pore sizes of the nickel foam forming the upper and lower layers may each independently be 30 ppi to 150 ppi. More specifically, the pore size of the nickel foam forming the intermediate layer may be 90 ppi or more, or 100 ppi or more, and 130 ppi or less, or 120 ppi or less. In addition, the pore sizes of the nickel foam forming the upper and lower layers may each independently be 30 ppi or more, or 50 ppi or more, and 150 ppi or less, or 120 ppi or less. Here, ppi refers to the number of pores per inch, and the higher the numerical value of ppi, the smaller the pore size.

[0097] Meanwhile, pressing of the laminate of the nickel foam can be performed using a roll press or a plate press.

[0098] The above pressing can be performed by applying a load so that the PTL to be finally manufactured has the above thickness. Specifically, it can be performed by applying a load of 3000 kg to 4000 kg at a speed of 30 m / min to 40 m / min. More specifically, the speed at which the load is applied during the pressing can be 30 m / min or more, or 32 m / min or more, or 35 m / min or more, and 40 m / min or less, or 38 m / min or less, or 36 m / min or less. In addition, the load during the pressing can be 3000 kg or more, or 3200 kg or more, or 3500 kg or more, and 4000 kg or less, or 3900 kg or less, or 3800 kg or less.

[0099] By the compression process under the above conditions, a porous transport membrane having a single-layer structure without an interlayer interface is manufactured.

[0100] In addition, the manufactured PTL is thin, so the material transfer distance in gaseous (O2) and liquid phases is short, allowing materials to move smoothly, and the contact area with the catalyst layer (CL) is large, so the contact resistance (Ohmic Resistance) can be reduced, and as a result, cell performance can be improved.

[0101] Accordingly, according to the present invention, an anion exchange membrane electrolysis system including the PTL is provided.

[0102] The above anion exchange membrane electrolysis system has the configuration of a conventional anion exchange membrane electrolysis system, except that it includes the above PTL.

[0103] Specifically, the anion exchange membrane electrolysis system according to the present invention includes an oxidation electrode (anode), a reduction electrode (cathode), and an anion exchange membrane interposed between the oxidation electrode and the reduction electrode, and further includes the PTL described above on the side opposite to the side of the oxidation electrode that is in contact with the anion exchange membrane.

[0104] Fig. 1 is a schematic diagram schematically illustrating the structure of an anion exchange membrane electrolysis system according to the present invention. Fig. 1 is merely an example for explaining the present invention, and the present invention is not limited thereto.

[0105] Referring to FIG. 1, the anion exchange membrane electrolysis system according to the present invention includes an anion exchange membrane (1) as an electrolyte membrane, a membrane-electrode assembly (MEA) (4) including an oxidation electrode (Anode) (2) and a reduction electrode (Cathode) (3) positioned on both sides of the anion exchange membrane, a porous transport membrane for the reduction electrode (or a porous gas diffusion layer (GDL) for the reduction electrode) (5a), a porous transport membrane for the oxidation electrode, the PTL (5b) described above, a bipolar plate (6a) for the reduction electrode, and a bipolar plate (6b) for the oxidation electrode. In addition, the electrolysis system may further optionally include gaskets between the separator and the porous transport membrane, and between the electrode and the porous transport membrane, respectively. For example, the electrolysis system may further include a gasket (7a) for the reduction electrode between the separator (6a) for the reduction electrode and the porous transport membrane (5a) for the reduction electrode, a gasket (7ba) for the oxidation electrode between the separator (6b) for the oxidation electrode and the porous transport membrane (5b) for the oxidation electrode, a sub-gasket (8a) for the reduction electrode between the reduction electrode (3) and the porous transport membrane (5a) for the reduction electrode, and a sub-gasket (8b) for the oxidation electrode between the oxidation electrode (2) and the porous transport membrane (5b) for the oxidation electrode. In addition, the electrolysis system may further include a current collector, specifically, a current collector (9a) for the reduction electrode and a current collector (9b) for the oxidation electrode, on the outer side of the separator, that is, on the side of the separator opposite to the side where the separator and the porous transport membrane are in contact. In addition, the above-described electrolysis system may further include an end plate, specifically, an end plate (10a) for a reduction electrode and an end plate (10b) for an oxidation electrode, on the outer side of the current collector, that is, on the side of the current collector opposite to the side where the current collector and the separator come into contact. A detailed description of each component constituting the above-described anion exchange membrane electrolysis system is omitted.

[0106] Hereinafter, the functions and effects of the invention will be described in more detail through specific examples. However, these examples are provided merely as examples of the invention and do not define the scope of the invention.

[0107]

[0108] The nickel foams used in the following examples and comparative examples are as follows:

[0109] Nickel foam No. 1: Ni foam manufactured by Seongji Materials Technology, 50 ppi (pores per inch) and average thickness 174.1㎛

[0110] Second nickel foam: Ni foam from Seongji Materials Technology, 80 ppi and average thickness 95.1㎛

[0111] Nickel foam 3: Ni foam from Seongji Materials Technology, 100 ppi and average thickness 66.7㎛

[0112] Nickel Foam No. 4: Ni foam from Seongji Materials Technology, 120 ppi and average thickness 66.0㎛

[0113]

[0114] Example 1

[0115] As described in Table 1 below, the first and second nickel foams were laminated according to the ppi value of the nickel foam, and then pressed three times at a speed of 35 m / min with a load of 3800 kg repeatedly applied to obtain a thickness of 340 μm using a LAB Pressing M / C (ACEY-HRP100, manufactured by Xiamen Acey New Energy Technology Co., Ltd.), thereby manufacturing a porous transport membrane having a single-layer structure.

[0116]

[0117] Examples 2 to 4 and Comparative Examples 1 to 7

[0118] A porous transport membrane was manufactured in the same manner as in Example 1, except that the first to fourth nickel foams were laminated according to the ppi value of the nickel foam, as described in Table 1 below.

[0119]

[0120] Pore ​​size (ppi) in nickel foam Top Mid Bottom Example 11 20 120 50 Example 2 50 100 100 Example 3 100 100 100 Example 4 50 120 120 Comparative Example 11 20 50 120 Comparative Example 2 50 50 50 Comparative Example 3 100 50 100 Comparative Example 4 80 120 80 Comparative Example 5 120 50 50 Comparative Example 6 100 80 100 Comparative Example 7 50 50 120

[0121]

[0122] Experimental Example 1: Measurement of pore size and porosity

[0123] The porous transport membranes manufactured in the above examples and comparative examples were measured through micro CT (micro computed tomography) photography and simulation using Geodict, a structural analysis software.

[0124] Specifically, a porous transport membrane was photographed in real life using a Micro CT (SkyScan1176 micro CT from Bruker), and then its internal structure was 3D scanned to create a 3D model. Subsequently, a simulation was performed using Geodict's PoroDict, which utilizes the same mechanism as the mercury infiltration method, and the results were used to measure pore sizes (D10, D50, D90) and porosity (%). The porosity was calculated using the following mathematical equation (2).

[0125]

[0126] <Micro CT 촬영시 설정 조건>

[0127]

[0128] <Simulation setting conditions>

[0129]

[0130]

[0131] [Equation 2]

[0132]

[0133] In the above mathematical formula 2,

[0134] is the porosity (%) of the porous transport membrane,

[0135] is the density of the porous transport membrane (g / cm 3 ), and is calculated by dividing the mass of the porous transport membrane by its volume according to the Archimedes method.

[0136] is the density of Ni (g / cm 3 ).

[0137]

[0138] In addition, the results of simulating the cross-sections of the PTLs of Comparative Examples 2, 6, and 9 when cut in the thickness direction using Geodict are shown in Figures 2A to 3B.

[0139] Figures 2a and 2b are the results of simulating the lateral cross-section (xy cross-section) of the PTL of Comparative Examples 2 and 6, respectively, when cut in the thickness direction, using Geodict.

[0140] Figures 3a and 3b are the results of simulating the lateral cross-section (yz cross-section) of the PTL of Comparative Examples 6 and 9, respectively, when cut in the thickness direction, using Geodict.

[0141]

[0142] Porosity [%]D10 [nm]D50 [nm]D90 [nm]Example 139.4525.8662.63111.82Example 263.8127.3074.84153.89Example 357.2033.2084.41142.56Example 439.4525.8662.63111.82Comparative Example 163.6639.98102.38191.77Comparative Example 249.64 38.5094.26176.41Comparative Example 362.0925.2465.26124.09Comparative Example 454.4023.7960.2113.98Comparative Example 554.4525.5167.99128.05Comparative Example 650.9328.3272.09129.03Comparative Example 754.4525.5167.99128.05

[0143]

[0144] Experimental Example 2: Contact Area Ratio (%)

[0145] In the same manner as in Experimental Example 1 above, after real-world photography and implementation of a 3D model using Micro CT, the total surface area (A) of the porous transport membrane on the side where the porous transport membrane contacts the electrode and the actual contact area (B) between the porous transport membrane and the electrode were measured through simulation using Geodict, a structural analysis tool, and then the contact area ratio (%) was calculated according to the following mathematical equation 1.

[0146] [Mathematical Formula 1]

[0147] Contact area ratio (%) = (B / A) x 100

[0148] In the above mathematical formula 1,

[0149] A is the total surface area (m) of the porous transport membrane on the side where the porous transport membrane is in contact with the electrode. 2 ) and,

[0150] B is the actual contact area (m) of the porous transport membrane and the electrode. 2 )am.

[0151]

[0152] Contact area ratio [%] Example 1 27.71 Example 2 29.74 Example 3 42.95 Example 4 32.93 Comparative Example 1 21.19 Comparative Example 2 25.08 Comparative Example 3 23.23 Comparative Example 4 25.66 Comparative Example 5 14.04 Comparative Example 6 25.35 Comparative Example 7 23.26

[0153]

[0154] Experimental Example 3: Flexural Strength Measurement

[0155] In the same manner as in Experimental Example 1, after real-world photography and 3D model implementation using Micro CT, simulation was performed using Geodict, a structural analysis tool, and the results were used to calculate the geometric tortuosity (τ) according to the following mathematical equation 3. A tortuosity of 2.90 or more and 3.50 or less was evaluated as excellent.

[0156] [Equation 3]

[0157] τ=Le / Ls

[0158] In the above mathematical formula 3,

[0159] Ls is the thickness of PTL (㎛),

[0160] Le is the average movement distance (㎛) of a substance passing through the thickness direction of the porous transport membrane.

[0161] In addition, the results of the evaluation of the bending rate for the PTL of Example 2, Comparative Example 2, Comparative Example 3, and Comparative Example 6 are shown in Fig. 4.

[0162]

[0163] Geometric tortuosity (τ) Example 13.22 Example 22.95 Comparative Example 12.49 Comparative Example 23.04 Comparative Example 33.61 Comparative Example 52.80 Comparative Example 63.13 Comparative Example 72.49

[0164]

[0165] Experimental Example 4

[0166] (1) Electrical conductivity (S / m)

[0167] Using the same method as in Experimental Example 1, real-world photography and 3D modeling were performed using Micro CT. Then, using Geodict, a structural analysis tool, the electrical conductivity of the porous transport membrane was simulated and measured according to its structure. The higher the electrical conductivity value in the upper layer of the porous transport membrane (the surface in contact with the electrode), the better the performance.

[0168]

[0169] (2) Initial potential (V) (@1.5A / cm) 2 )(20h)

[0170] The initial voltage was measured using the electrochemical workstation (EC-LAB) of Potentiostation.

[0171] Specifically, a cell with an active area of ​​5 cm² was used, and the open-circuit voltage (OCV) was stabilized by leaving it for 20 hours before measurement. Under the operating conditions of 70°C and 10 ml / min flow rate, a current density of 1.5 A / cm² was applied, the voltage was increased from 1.2 V to 2.0 V at a rate of 2.0 mV / s, and the voltage of the cell was measured at 2.0 mV intervals. At this time, the smaller the initial voltage, the better.

[0172]

[0173] (3) Durability (μV / h)

[0174] Durability was measured using an electrochemical workstation (CNL) with an alkaline electrolysis system.

[0175] Specifically, a cell with an active area of ​​5 cm² was used and operated under the conditions of a temperature of 70°C and a flow rate of 10 ml / min. The voltage of the cell was measured at 1-second intervals for 60 hours under the condition of a constant current density of 1.5 A / cm². The voltage degradation rate for 60 hours was calculated using the difference (μV) between the final voltage and the initial voltage according to the following mathematical equation 4. The smaller the voltage degradation rate, the better the durability.

[0176] [Equation 4]

[0177] Voltage drop rate (μV / h) = (final voltage - initial voltage) / operating time

[0178] In the above mathematical expression 4, the final voltage is the voltage measured when the operating time is 60 hours, and the initial voltage is the voltage measured when the operating time is 1 second.

[0179]

[0180] Electrical conductivity (S / m)Initial Potential [V] @ 1.5A / cm² (20h)Durability [μV / h]Example 18.18 xe 6 1.725538.36 Example 25.36 xe 6 1.722343.57 Example 34.14 xe 6 1.726644.25 Example 48.18 xe 6 1.706533.93Comparative Example 1-1.7590Comparative Example 25.85 xe 6 1.742355.81Comparison Example 35.40 xe 6 1.741508.38Comparison Example 47.11 xe 6 1.732513.82Comparative Example 5-1.741508.38Comparative Example 64.49 xe 6 1.752341.05Comparison Example 77.07 xe 6 1.744539.80

[0181] In the above table, “-“ means not measured.

[0182] As a result of the measurement, the porous transport membrane of the example was 4.00 xe 6 It exhibited a high electrical conductivity of more than S / m, and the battery containing it also exhibited an initial voltage of less than 1.73 V and a durability of less than 600 μV / h, confirming that the battery performance improvement effect was excellent.

[0183] Meanwhile, the porous transport membrane of the comparative example has an electrical conductivity of 7.11 xe 6 The battery performance was lower than S / m, and the battery containing it showed deteriorated battery performance with an initial voltage of 1.732 V or higher. In particular, Comparative Example 4 showed a large voltage enhancement rate of 757 μV / h or higher, confirming that durability was significantly reduced.

Claims

1. Contains nickel foam, A porous transport membrane having a contact area ratio of 27.00% to 92.00% according to the following mathematical formula 1: [Mathematical Formula 1] Contact area ratio (%) = (B / A) x 100 In the above mathematical formula 1, A is the total surface area (m) of the porous transport membrane on the side where the porous transport membrane is in contact with the electrode. 2 ) and, B is the actual contact area (m) of the porous transport membrane and the electrode. 2 )am.

2. In paragraph 1, A porous transport membrane, wherein the pore size D50 within the porous transport membrane is 60.00 nm to 100.00 nm.

3. In paragraph 1, The above porous transport membrane is a porous transport membrane having a pore size D10 of 25.00 nm to 35.00 nm.

4. In paragraph 1, The above porous transport membrane is a porous transport membrane having a pore size D90 of 110.00 nm to 160.00 nm., Porous transport membrane.

5. In paragraph 1, The above porous transport membrane is a porous transport membrane having a porosity of 30.00% to 70.00% calculated according to the following mathematical formula 2: [Equation 2] In the above mathematical formula 2, is the porosity (%) of the porous transport membrane, is the density of the porous transport membrane (g / cm 3 ), and is calculated by dividing the mass of the porous transport membrane by its volume according to the Archimedes method. is the density of Ni (g / cm 3 )am.

6. In paragraph 1, The porous transport membrane above is a porous transport membrane having a curvature (τ) of 2.00 to 5.00 calculated according to the following mathematical formula 3: [Equation 3] τ=Le / Ls In the above mathematical formula 3, Ls is the thickness of the porous transport membrane, which means the length of the porous transport membrane in the direction in which the substance moves toward the electrode side in contact with the porous transport membrane when applying the porous transport membrane to the anion exchange membrane. Le is the average distance traveled by the material in the thickness direction of the porous transport membrane.

7. In paragraph 1, The above porous transport membrane is a porous transport membrane having a single layer structure.

8. In paragraph 1, The porous transport membrane has a thickness of 300 ㎛ to 400 ㎛.

9. In paragraph 1, The above porous transport membrane is 4.00 xe 6 A porous transport membrane exhibiting an electrical conductivity of S / m or greater. 10.3 Step of manufacturing a laminate by laminating nickel foams; and A step of compressing the above laminate is included, A method for manufacturing a porous transport membrane according to claim 1, wherein, when manufacturing the laminate, nickel foam is laminated so that the pore size of each layer satisfies any one of the following conditions (i) to (iii), when dividing the upper layer, middle layer, and lower layer according to the position in the thickness direction of the laminate: (i) Upper layer < Middle layer ≤ Lower layer (ii) Upper layer ≥ Middle layer > Lower layer (iii) Upper layer = Middle layer = Lower layer.

11. In paragraph 10, A manufacturing method wherein, during the lamination, the pore size of the nickel foam forming the middle layer is 90 ppi to 130 ppi, and the pore sizes of the nickel foam forming the upper and lower layers are each independently 30 ppi to 150 ppi.

12. In paragraph 10, A manufacturing method wherein the three nickel foams above each independently have a thickness of 50 ㎛ to 200 ㎛.

13. In paragraph 10, A manufacturing method in which, in the above three nickel foams, the smaller the size of the pores within the nickel foam, the thinner the thickness of the nickel foam.

14. In paragraph 10, A manufacturing method in which the above pressing is performed by applying a load of 3000 kg to 4000 kg at a speed of 30 m / min to 40 m / min to the laminate so that the final manufactured thickness is 300 μm to 400 μm.

15. Including an oxidation electrode, a reduction electrode, and an anion exchange membrane interposed between the oxidation electrode and the reduction electrode, Further comprising a porous transport membrane according to claim 1 on the opposite side of the oxidation electrode surface in contact with the anion exchange membrane. Anion exchange membrane electrolysis system.

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