Porous transport layer, composition for forming porous transport layer, and method of forming porous transport layer

Abstract

A porous transport layer, a composition for forming a porous transport layer, and a method of forming a porous transport layer are presented. The porous transport layer comprises 30 to 80 wt% of a metal fibrous material and 20 to 70 wt% of a metal particulate material, relative to the total weight of the layers. In this case, each metal of the metal fiber-type material and the metal particle-type material includes a metal selected from the group consisting of titanium, zirconium, hafnium, nickel, stainless steel, and combinations thereof.

Description

Technical Field

[0001] The present disclosure relates to a porous transport layer, a composition for forming the porous transport layer, and a method for preparing the same. Background Art

[0002] Anodes in polymer electrolyte membrane (PEM) water electrolysis systems are subjected to harsh conditions, and thus a porous transport layer (PTL) made of a material such as titanium instead of a carbon material is being applied. The PTL is located between the anode and the diaphragm and is used to cause water electrolysis and oxygen evolution reactions. The PTL is considered to be part of the water electrolysis system where degradation occurs and is considered a key factor in determining performance, durability, and manufacturing cost.

[0003] Generally, such a PTL can be applied to a porous sintered body. However, there is a need for research and development of a sintered body that can be operated under water electrolysis conditions at the kW level at high temperature and high pressure, minimize the formation of irregular pores with horizontal orientation, and obtain appropriate mechanical strength.

[0004] The information disclosed in this background art section of the present disclosure is only for enhancing the understanding of the general background of the present disclosure and should not be regarded as an admission or any form of indication that this information forms related art already known to those skilled in the art. Summary of the Invention

[0005] Aspects of the present disclosure relate to providing a porous transport layer (PTL) that exhibits excellent performance both at low current and high current, obtains good porosity, gas permeability, and strength, and promotes the movement of reactants and products.

[0006] The object of the present disclosure is not limited to the above object. The above and other objects of the present disclosure will become more apparent from the following description and are achieved by the appended claims and their combinations.

[0007] To achieve the above object, according to an exemplary embodiment of the present disclosure, a porous transport layer (PTL) includes: 30 to 80 wt% of a metal fiber type material and 20 to 70 wt% of a metal particle type material, based on the total weight of the layer, wherein each metal in the metal fiber type material and the metal particle type material includes a metal selected from the group consisting of titanium, zirconium, hafnium, nickel, stainless steel, and combinations thereof.

[0008] In an exemplary embodiment of the present disclosure, the metal fiber type material may have an average diameter of 10 μm to 50 μm.

[0009] In an exemplary embodiment of the present disclosure, the length of the metal fiber type material may correspond to 30 to 1,000 times the diameter of the metal fiber type material.

[0010] In an exemplary embodiment of the present disclosure, the metal particulate material may be derived from a metal particulate raw material having an average particle size of 5 to 80 μm.

[0011] In an exemplary embodiment of the present disclosure, the porous transport layer may have a surface Ra roughness of 2.5 to 9.5 μm.

[0012] In an exemplary embodiment of the present disclosure, the porous transport layer may have a porosity of 30% to 60%.

[0013] In an exemplary embodiment of the present disclosure, the porous transport layer may have 2.8·10 -3 to 8.2·10 -3 cm 4 / gf·s of gas permeability.

[0014] In an exemplary embodiment of the present disclosure, the porous transport layer may have a thickness of 100 to 1000 μm.

[0015] To achieve the above object, according to an exemplary embodiment of the present disclosure, a composition for forming a porous transport layer (PTL) includes: a metal fiber raw material; a metal particulate raw material; and a solvent, wherein, relative to the total weight of the metal fiber raw material and the metal particulate raw material, the metal fiber raw material and the metal particulate raw material have contents of 30 wt% to 80 wt% and 20 wt% to 70 wt%, respectively, and each metal in the metal fiber raw material and the metal particulate raw material includes a metal selected from the group consisting of titanium, zirconium, hafnium, nickel, stainless steel, and combinations thereof.

[0016] In an exemplary embodiment of the present disclosure, the composition for forming the porous transport layer may further include a binder and a dispersant, such that the composition includes: 21.3 to 56.8 wt% of the metal fiber raw material, 14.2 to 49.7 wt% of the metal particulate raw material, 0.1 to 4 wt% of the binder, and 0.1 to 3 wt% of the dispersant.

[0017] In an exemplary embodiment of the present disclosure, the dispersant may include one selected from the group consisting of: water, ethanol, methanol, isopropanol, xylene, cyclohexanone, acetone, methyl ethyl ketone, and combinations thereof.

[0018] In an exemplary embodiment of the present disclosure, the binder may include one selected from the group consisting of polyvinyl butyral, polyvinyl alcohol, polyvinyl chloride, polyvinyl acetate, polyacrylonitrile, and combinations thereof.

[0019] To achieve the above object, according to an exemplary embodiment of the present disclosure, a method of forming a porous transport layer (PTL) includes: (a) removing fat from the above composition through a defatting process at a predetermined temperature, and (b) sintering the resulting product obtained in (a).

[0020] In an exemplary embodiment of the present disclosure, (a) may further include a process of shaping the composition.

[0021] In an exemplary embodiment of the present disclosure, the defatting process in (a) may be carried out at a temperature of 300°C to 700°C.

[0022] In an exemplary embodiment of the present disclosure, the sintering in (b) may be carried out at a temperature of 900°C to 1400°C and a vacuum level of 10 -5 Torr or less.

[0023] According to an exemplary embodiment of the present disclosure, the porous transport layer can obtain good porosity, gas permeability, and strength, while preventing damage to the electrode or other components during the formation process.

[0024] According to another exemplary embodiment of the present disclosure, a water electrolysis system applying the porous transport layer can exhibit excellent performance both at low current and high current, and promote the movement of reactants (water) and products (oxygen).

[0025] The effects of the present disclosure are not limited to the above effects. It should be understood that the effects of the present disclosure include all effects that can be derived from the following description.

[0026] The method and apparatus of the present invention have other features and advantages that will be apparent from or more particularly set forth in the accompanying drawings and the following detailed description, which are incorporated herein and together serve to explain certain principles of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic diagram briefly showing a porous transport layer (PTL) according to an exemplary embodiment of the present disclosure;

[0028] Figure 2 is a schematic diagram briefly showing a method of forming a porous transport layer according to an exemplary embodiment of the present disclosure; and

[0029] Figure 3 is a schematic diagram briefly showing a composition for forming a porous transport layer according to an exemplary embodiment of the present disclosure.

[0030] It will be understood that the drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrating the basic principles of the present disclosure. Specific design features of the invention as disclosed herein, including, for example, specific dimensions, orientations, positions, and shapes, will be determined in part by the particular intended application and use environment.

[0031] In the drawings, throughout several views of the drawings, reference numerals refer to the same or equivalent components of the invention. Detailed Description

[0032] Reference will now be made in detail to various embodiments of the invention, examples of which are illustrated in the drawings and described below. Although the disclosure will be described in connection with the exemplary embodiments of the present disclosure, it should be understood that this specification is not intended to limit the disclosure to those exemplary embodiments. On the contrary, the disclosure is intended to cover not only the exemplary embodiments of the disclosure, but also various alternatives, modifications, equivalents, and other embodiments that may be included within the spirit and scope of the disclosure as defined by the appended claims.

[0033] The above objects, other objects, features, and advantages of the present disclosure will be readily understood from the following exemplary embodiments in conjunction with the accompanying drawings. However, the present disclosure is not limited to the embodiments described herein and may be embodied in other forms. The embodiments described herein are provided so that this disclosure will be thorough and complete, and the spirit of the disclosure may be fully conveyed to those skilled in the art. Throughout the drawings, the same elements are denoted by the same reference numerals. In the drawings, for the clarity of the present disclosure, the dimensions of the structure are larger than the actual dimensions.

[0034] The terms "first", "second", etc. as used herein may be used to describe various components, but these components should not be construed as limited to these terms. These terms are only used for the purpose of distinguishing one component from another. For example, without departing from the scope of the present disclosure, the first component may be referred to as the second component, and the second component may also be referred to as the first component. Unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" as used herein are also intended to include the plural forms. It should be further understood that the terms "comprising", "including", or "having" when used herein specify the presence of the stated features, regions, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, regions, wholes, steps, operations, elements, components, and / or combinations thereof.

[0035] It should also be understood that when an element such as a layer, film, region, or sheet is referred to as being "on" another element, it can be directly on the other element or there can be intervening elements therebetween. Similarly, when an element such as a layer, film, region, or sheet is referred to as being "under" another element, it can be directly under the other element or there can be intervening elements therebetween.

[0036] Unless otherwise specified, all numerical values, values, and / or representations of amounts of components, reaction conditions, polymer compositions, and mixtures used herein should be considered approximate values, including the various uncertainties affecting the measurements, which inherently occur in obtaining such values, etc., and should thus be understood to be modified by the term "about" in all cases.

[0037] In addition, when a numerical range is disclosed herein, the range is continuous and includes all values from the minimum value of the range to its maximum value, unless otherwise indicated. In addition, when such a range relates to integer values, all integers from the minimum value to the maximum value are included, unless otherwise indicated.

[0038] When a sintered body sintered after forming ordinary particles is applied to the porous transport layer of a water electrolysis system, there is a possibility that the liquid phase, the inflow of reactants, and the discharge of oxygen (products) cannot be properly achieved. In addition, the mass transfer resistance may be high, making it difficult to form a porous transport layer having a predetermined or greater thickness. Furthermore, there are problems that the performance may be poor in a low current state, the flexural rigidity is low, and the forming is difficult.

[0039] When fibers are applied to such a porous transport layer, it is difficult to obtain appropriate surface roughness. Therefore, the contact area between the catalyst electrode layer, adjacent components, and the separator is small, thereby reducing the reaction area. In addition, when assembling a water electrolysis cell, there may be problems that the pressure becomes too high, the structure of the catalyst electrode layer is damaged, and it is difficult to obtain a predetermined strength.

[0040] The inventors of the present disclosure have developed a porous transport layer in which a metal fiber-type material and a metal particle-type material are mixed in an optimal weight ratio to minimize these problems. Hereinafter, the porous transport layer will be described in detail.

[0041] Porous transport layer 10

[0042] Refer to Figure 1, according to an exemplary embodiment of the present disclosure, the porous transport layer 10 includes: 30 to 80 wt% of a metal fiber type material 1 and 20 to 70 wt% of a metal particle type material 2, based on the total weight of the layer, wherein each metal in the metal fiber type material 1 and the metal particle type material 2 includes a metal selected from the group consisting of titanium, zirconium, hafnium, nickel, stainless steel, and combinations thereof. For example, the porous transport layer 10 may include titanium.

[0043] The porous transport layer 10 may have a form in which the metal particle type material 2 is introduced into the gaps, pores, and surfaces between the metal fiber type material 1.

[0044] The metal fiber type material 1 may partially or completely include one selected from the group consisting of a mesh net manufactured by selective metal fiber manufacturing, a felt, and combinations thereof.

[0045] The metal fiber type material 1 may have a content of 30 to 80 wt%, 40 to 75 wt%, or 50 to 65 wt% based on the total weight of the layer. In addition, the metal particle type material 2 may have a content of 20 to 70 wt%, 25 to 60 wt%, or 35 to 50 wt% based on the total weight of the layer. By falling within the above numerical ranges, satisfactory surface roughness and mass transfer resistance characteristics suitable for a water electrolysis cell can be obtained. In addition, the processing efficiency can be improved.

[0046] The metal fiber type material 1 may have an average diameter (wire diameter) of 10 to 50 μm, 12 to 45 μm, or 15 to 40 μm. When the average diameter of the metal fiber type material 1 is less than the above numerical range, the porosity may not be formed at a high level, resulting in an increase in mass transfer resistance. On the contrary, when the average diameter of the metal fiber type material 1 exceeds the above numerical range, the physical properties and mass may deviate severely due to the deviation in position, and the porosity may be too high.

[0047] The metal fiber type material 1 may have a length corresponding to 30 times to 1,000 times or 50 times to 500 times its diameter (the average diameter of the metal fiber type material). By falling within the above numerical ranges, satisfactory surface roughness and mass transfer resistance characteristics applicable to a water electrolysis cell can be obtained while minimizing the deviation of physical properties and mass.

[0048] The metal fiber type material 1 may be derived from a metal fiber type raw material having the average diameter and length as described above, and may include those in which this form is partially maintained. The diameter and length of the metal fiber type raw material may actually be the same as the diameter and length of the metal fiber type material 1.

[0049] The average diameter and length of the metal fiber type material 1 can be confirmed and measured through images taken by a scanning electron microscope (SEM).

[0050] The metal fiber type material 1 and the metal particle type material 2 can respectively be derived from a metal fiber type raw material and a metal particle type raw material. Alternatively, the metal fiber type material 1 and the metal particle type material 2 can be those that have been sintered, aggregated, necked (thinned), grown, and densified, or those obtained by sintering using specific additives by controlling the sintering time and conditions of the sintering process (without involving common subsequent steps of sintering, coarsening, densifying, and forming isolation holes). Based on the grain boundaries confirmed through images taken by a scanning electron microscope, the average particle size of the metal particle type material 2 can be the same as or larger than the average particle size of the metal particle type raw material. Additionally, the average diameter and length of the metal fiber type material 1 can be the same as or slightly larger than the average diameter and length of the metal fiber type raw material, which can actually be the same.

[0051] The metal particle type raw material can have an average particle size of 5 to 80 μm, 6 to 60 μm, or 8 to 40 μm, D 50 particle size. When the average particle size of the metal particle type raw material is less than the above numerical range, there may be the following problems: the porous transport layer has an extremely low porosity and the extremely small pore size becomes more brittle. On the contrary, when the average particle size of the metal particle type raw material exceeds the above numerical range, the porous transport layer may have an extremely high porosity and surface roughness, making it difficult to exhibit appropriate physical properties as a composite. In addition, the performance of the water electrolysis cell may be poor.

[0052] D 50 The particle size can correspond to the particle size when the cumulative weight percentage reaches 50% in the cumulative distribution graph (particle size distribution) of the weight fraction measured by a particle size analyzer.

[0053] The metal particle type raw material can have a circular, elliptical, polygonal, or irregular form. When the metal particle type raw material has a circular form, the size can correspond to the diameter. On the contrary, when the metal particle type raw material has a non-circular form, the size can correspond to the maximum length.

[0054] The porous transport layer can have a surface Ra roughness of 2.5 to 9.5 μm or 2.8 to 7.5 μm. By falling within the above numerical range, the bonding with the catalytic electrode layer of the water electrolysis cell can be stably performed, and the deterioration of adjacent components can be minimized.

[0055] The porous transport layer 10 may have a predetermined pore size and may have pore channels. The pore size may be in the range of 1 to 70 μm or 2 to 50 μm. In addition, the porosity of the porous transport layer 10 may be 30% to 60% or 38% to 52%. By falling within the above numerical ranges, appropriate strength and rigidity can be obtained while reducing the mass transfer resistance. In addition, the movement of liquid water, reactants, and gaseous oxygen (products) can be promoted.

[0056] The porous transport layer 10 may have 2.8·10 -3 to 8.2·10 -3 cm 4 / gf·s or 3.8·10 -3 to 6.2·10 - 3 cm 4 / gf·s of gas permeability. By falling within the above numerical ranges, the movement of liquid water, reactants, and gaseous oxygen (products) can be promoted.

[0057] The gas permeability in units of 10 -3 cm 4 / gf·s may correspond to the permeation rate / membrane thickness and the permeability coefficient (10 -3 cm 3 ·cm / cm 2 ·sec·gf·cm -2 ) at a room temperature of 25 °C, and can be converted to the barrers unit (10 -10 cm 3 ·cm / cm 2 ·sec·cmHg) by multiplying by a specific value.

[0058] The thickness of the porous transport layer 10 may be 100 to 1000 μm or 160 to 700 μm.

[0059] The porous transport layer 10 may be positioned adjacent to a catalytic electrode layer of a water electrolysis cell, a water electrolysis system, or an iridium-based electrode layer.

[0060] The porous transport layer 10 may be formed by removing fat from the composition for forming the porous transport layer, which will be described later, through a degreasing process, and then sintering the resulting product. In addition, the diffusion, growth, and densification of the raw materials can be controlled and avoided from occurring excessively during the sintering process to form a complex porous structure composed of a metal fiber type material and a metal particle type material.

[0061] The composition for forming the porous transport layer

[0062] Reference Figure 3, according to an exemplary embodiment of the present disclosure, the composition for forming a porous transport layer includes: a metal fiber type raw material, a metal particle type raw material, and a solvent. Among them, relative to the total weight of the metal fiber type raw material and the metal particle type raw material, the metal fiber type raw material and the metal particle type raw material respectively have a content of 30 to 80 wt% and 20 to 70 wt%, and each metal of the metal fiber type raw material and the metal particle type raw material includes a metal selected from the group consisting of titanium, zirconium, hafnium, nickel, stainless steel, and combinations thereof.

[0063] In the composition for forming a porous transport layer, the metal fiber type raw material may correspond to the initial form of the metal fiber type material 1 of the porous transport layer before sintering.

[0064] In the composition for forming a porous transport layer, the metal particle type raw material may correspond to the initial form of the metal particle type material 2 of the porous transport layer before sintering.

[0065] The diameter and length of the metal fiber type raw material may be substantially the same as those described above. The metal fiber type raw material may partially or completely include one selected from the group consisting of a screen selectively manufactured by metal fibers, a felt, and combinations thereof.

[0066] The average diameter and form of the metal particle type raw material may be substantially the same as those described above.

[0067] Relative to the total weight of the composition, the metal component contained in the entire metal fiber type raw material and the metal particle type raw material may have a content of 60 wt% to 98 wt%, 65 wt% to 85 wt%, or 70 wt% to 80 wt%. When the content of the metal component is less than the above numerical range, sintering may not proceed smoothly between the metal components. In addition, there is a problem that the formed porous transport layer may have too high a porosity or low rigidity. On the contrary, when the content of the metal component exceeds the above numerical range, the formed porous transport layer may have a low porosity or high viscosity, making it difficult to normally use the composition to manufacture molded products and molded sheets.

[0068] The composition for forming a porous transport layer may further selectively contain additives. In addition, materials for controlling the dispersion, binding strength, and bubbles of the components in the composition for forming a porous transport layer may be included.

[0069] The composition for forming a porous transport layer may further include an adhesive and a dispersant as additives, such that the composition includes: relative to the total weight of the composition, 21.3 to 56.8 wt% of the metal fiber type raw material, 14.2 to 49.7 wt% of the metal particle type raw material, 0.1 to 4 wt% of the adhesive, 0.1 to 3 wt% of the dispersant, and 10 to 30 wt% of the solvent.

[0070] Based on the total weight of the composition, the binder may have a content of 0.1 to 4 wt%, 1 to 4 wt%, or 2 to 3.5 wt%. When the content of the binder is less than the above numerical range, the bonding strength between the metal components in the porous transport layer to be formed may be insufficient, which causes problems in making molding difficult. On the contrary, when the content of the binder exceeds the above numerical range, the bonding strength between the components in the composition may be too high, which causes the problem that the composition adheres excessively when using a substrate or a mold for preparation.

[0071] The binder may include one selected from the group consisting of polyvinyl butyral, polyvinyl alcohol, polyvinyl chloride, polyvinyl acetate, polyacrylonitrile, and combinations thereof. For example, the binder may include a material that can be thermally degraded at a temperature of 500 °C or lower while allowing the bonding strength between the metal components to be maintained.

[0072] Based on the total weight of the composition, the dispersant may have a content of 0.1 to 3 wt%, 1 to 3 wt%, or 1.5 to 2.3 wt%. When the content of the dispersant is less than the above numerical range, the metal components in the composition may aggregate. On the contrary, when the content of the dispersant exceeds the above numerical range, the composition may have a low viscosity, which causes problems in formability and processability.

[0073] The dispersant may include one selected from the group consisting of water, ethanol, methanol, isopropanol, xylene, cyclohexanone, acetone, methyl ethyl ketone, and combinations thereof.

[0074] Based on the total weight of the composition, the solvent may have a content of 10 to 30 wt%, 15 to 30 wt%, or 20 to 30 wt%. When the content of the solvent is less than the above numerical range, the composition may have a high viscosity, which results in poor formability of the composition. Therefore, there is a problem that the formed porous transport layer has an uneven thickness, and the porosity and pore size deviate severely due to position. On the contrary, when the content of the solvent exceeds the above numerical range, excessive solvent evaporates during the sintering process, which causes contamination of the material and equipment. Or, it may be difficult to form a desired thickness and pore shape.

[0075] The solvent may contain alcohol materials and substituted or unsubstituted benzene materials, including ethanol, toluene, etc.

[0076] The composition for forming the porous transport layer may further contain an antifoaming agent. In the case where each metal in the metal particle type raw material and the metal fiber type raw material is titanium, the composition may contain TiH 2 .

[0077] Method for forming a porous transport layer

[0078] Reference Figure 2 According to an exemplary embodiment of the present disclosure, a method for forming a porous transport layer includes: (a) removing fat from the above composition through a defatting process at a predetermined temperature, and (b) sintering the resulting product obtained in (a).

[0079] (a) may further include a process of stirring the composition for forming the porous transport layer before performing the defatting process. For example, a ball milling process may be performed, and the stirring process may be carried out for 1 hour or longer, 10 to 30 hours, or 12 to 24 hours.

[0080] (a) may further include a process of shaping the composition for forming the porous transport layer. The shaping process may be performed after the stirring process. For example, the shaping process may be a process of coating a release paper or a substrate with the composition for forming the porous transport layer, or may be a process of injecting the composition for forming the porous transport layer into a mold and applying pressure.

[0081] The coating process may be selected from the group consisting of: dip coating, doctor blade coating, comma coating, screen printing coating, tape casting, slot die coating, gravure coating, lipcoating, and rod coating.

[0082] For example, the coating process may be doctor blade coating, wherein the coating speed is in the range of 0.3 m / min to 1 m / min.

[0083] It may include a process of cutting the sheet formed after the coating process into a predetermined length.

[0084] The defatting process in (a) may be performed at a temperature of 300 °C to 700 °C, 350 °C to 600 °C, or 400 °C to 500 °C in an inert gas atmosphere. When the temperature during the defatting process is lower than the above numerical range, there may be problems such as incomplete evaporation of the solvent and thus residue. On the other hand, when the temperature during the defatting process is higher than the above numerical range, there may be a problem of partial oxidation of the metal components due to the lack of a high vacuum atmosphere.

[0085] An inert gas such as argon may be applied to the defatting process in (a).

[0086] The defatting process in (a) may be performed by raising the temperature to the above numerical temperature range at a heating rate of 1 °C / min to 3 °C / min and maintaining the same temperature for 1 to 5 hours.

[0087] (b) The sintering can be carried out at a temperature of 900 °C to 1400 °C, 950 °C to 1300 °C, or 950 °C to 1150 °C. When the temperature during the sintering process is lower than the above numerical range, the metal components in the composition or molded article may not be sintered, which causes problems such as excessive pores or reduced rigidity. On the contrary, when the temperature during the sintering process exceeds the above numerical range, the metal components in the composition or molded article may be oxidized. Or, there may be a problem that the porous transport layer is contaminated by contaminants in the sintering furnace. In addition, there may be a possibility of wasting process costs and energy.

[0088] (b) The sintering can be carried out at a vacuum level of 1×10 -5 Torr or less, 1×10 -8 to 1×10 -5 Torr, or 1×10 -7 to 5×10 -6 Torr. The sintering in (b) can be carried out for 0.3 to 5 hours or 0.5 to 4 hours. By satisfying the above conditions, overgrowth and densification can be prevented during the sintering process, while obtaining the desired porosity and mechanical properties.

[0089] After the sintering in (b), it may include a process of maintaining the same vacuum level while performing furnace cooling.

[0090] The method of forming the porous transport layer enables the above-mentioned porous transport layer 10 to be easily implemented.

[0091] Hereinafter, the present disclosure will be described in detail with reference to the following examples and comparative examples. However, the spirit of the present disclosure is not limited thereto.

[0092] Example 1 - Composite PTL Formation 1

[0093] Prepare a composition for forming a porous transport layer (PTL). The composition contains: 35.5 wt% of titanium fibers having an average diameter (wire diameter) of 35 μm and a length corresponding to 57 times its diameter, 35.5 wt% of amorphous titanium powder having an average particle size (D 50 ) of 32 μm, 3.5 wt% of a polyvinyl butyral binder, 1.5 wt% of an isopropyl alcohol dispersant, and 24 wt% of an ethanol solvent.

[0094] Use the composition for forming the PTL to coat a substrate by doctor blade coating so that the width, height, and thickness are 60 mm, 60 mm, and 260 μm, respectively, to form a green sheet. Then, while raising the temperature at a heating rate of 1 °C / minute in an argon atmosphere, once the temperature reaches 420 °C, a debinding process is carried out for 2 hours.

[0095] Next, under a high vacuum of 5×10 -6 Torr, while raising the temperature at a heating rate of 3°C per minute, once the temperature reaches 1070°C, sintering is carried out for 1 hour. Thereafter, PTL is formed by furnace cooling while maintaining the same vacuum level.

[0096] Example 2 - Composite PTL Formation 2

[0097] PTL is formed in the same manner as in Example 1, except that the contents of titanium fibers and titanium powder are changed to 46.15 wt% and 24.85 wt%, respectively.

[0098] Comparative Example 1 - PTL Formation 1

[0099] PTL is formed in the same manner as in Example 1, except that the content of titanium powder is changed to 71 wt% and no titanium fibers are contained.

[0100] Comparative Example 2 - PTL Formation 2

[0101] PTL is formed in the same manner as in Example 1, except that the content of titanium fibers is changed to 71 wt% and no titanium powder is contained.

[0102] Experimental Example 1 - Measurement of Gas Permeability, Porosity, and Surface Roughness

[0103] The gas permeability, porosity, and surface roughness of the PTLs in the above examples and comparative examples were measured by the following method. The results are shown in Table 1 below.

[0104] Gas Permeability: While supplying oxygen to the upper part of the PTL at a pressure of 1 kgf / cm 2 and connecting a vacuum pump to the lower part of the PTL to maintain a vacuum, pressure sensors were installed at the upper and lower parts to observe the pressure change. In addition, a thermal mass flowmeter (MFM) was prepared at the lower part to continuously measure the flow rate (flow rate, velocity) of the permeating gas to calculate the gas permeability P.

[0105] P = Vl / AtdP, where V, I, A, t, and dP refer to the average gas flow rate (cm 3 / s), PTL thickness (cm), PTL area (cm 2 ), permeation time (seconds), and pressure difference, respectively.

[0106] Porosity: An image of the PTL was taken with a scanning electron microscope, and the pore volume fraction and porosity were measured using image analysis software (ImageJ).

[0107] Surface roughness: The surface roughness values of the core and nine peripheral parts with a size of 10 μm × 10 μm in the PTL were measured by an atomic force microscope (AFM). Then, the average value was calculated.

[0108] [Table 1]

[0109]

[0110]

[0111] It can be determined from Table 1 that, compared with the cases of the comparative examples containing a single powder or a single fiber, the examples containing Ti powder and Ti fiber at a predetermined mixing ratio achieved the desired gas permeability, porosity, and Ra roughness.

[0112] Experimental Example 2 - Performance Analysis of the Water Electrolysis Cell

[0113] The PTLs of Example 1 and Comparative Example 1 were each independently applied to the anode layer of the water electrolysis cell, where an iridium (Ir) catalyst was used as the anode layer, a carbon-supported platinum (Pt / C) catalyst was used as the cathode layer, and Nafion 115 was used as the separator. Then, the performance of the water electrolysis cell with a cross-sectional area of 2500 mm 2 was analyzed.

[0114] In the case of applying the porous transport layer of Example 1, it was determined that, compared with the case of the PTL of Comparative Example 1, the oxygen generated on the surface of the negative electrode catalyst moved smoothly both at low current and high current, while promoting the penetration of liquid water (reactants), and the mass transfer resistance was low.

[0115] In the exemplary embodiments of the present disclosure, it should be understood that terms such as "including" or "having" are intended to specify the presence of the features, values, steps, operations, elements, components, or combinations thereof described in the specification, and do not exclude the possibility of adding or existing one or more other features, values, steps, operations, elements, components, or combinations thereof.

[0116] According to the exemplary embodiments of the present disclosure, when one or some components can be omitted, the components can be implemented in combination with each other.

[0117] For purposes of illustration and description, the above description of specific exemplary embodiments of the invention has been presented. They are not intended to be exhaustive or to limit the disclosure to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. To explain certain principles of the disclosure and their practical applications, exemplary embodiments have been selected and described so that others skilled in the art can make and utilize the various exemplary embodiments of the invention and their various alternatives and modifications. The scope of the disclosure is intended to be defined by the appended claims and their equivalents.

Claims

1. A porous transmission layer, comprising: 30 to 80 wt% of a metal fiber type material; as well as 20 to 70 wt% of a metallic particle-type material, relative to the total weight of the layer, Wherein, each metal in the metal fiber type material and the metal particle type material comprises a metal selected from the group consisting of: titanium, zirconium, hafnium, nickel, stainless steel and combinations thereof.

2. The layer according to claim 1, wherein The metal fiber type material has an average diameter of 10 to 50 μm.

3. The layer according to claim 2, wherein The length of the metal fiber type material corresponds to 30 to 1,000 times the diameter of the metal fiber type material.

4. The layer according to claim 1, wherein The metal particle type material is derived from a metal particle type raw material having an average particle size of 5 to 80 μm.

5. The layer according to claim 1, wherein The layer has a surface Ra roughness of 2.5 to 9.5 μm.

6. The layer according to claim 1, wherein The porous transport layer has a predetermined pore size and pore channel in the range of 1 to 70 μm.

7. The layer according to claim 1, wherein The layer has a porosity of 30% to 60%.

8. The layer according to claim 1, wherein The layer has a 2.8·10 -3 To 8.2·10 -3 cm 4 / gf·s gas permeability.

9. The layer according to claim 1, wherein The layer has a thickness of 100 to 1000 μm.

10. A composition for forming a porous transport layer, the composition comprising: Metal fiber type raw materials; Metal granular raw materials; and Solvents, in, The metal fiber type raw material and the metal particle type raw material have contents of 30 wt % to 80 wt % and 20 wt % to 70 wt % respectively relative to the total weight of the metal fiber type raw material and the metal particle type raw material, and Wherein, each of the metal fiber type raw material and the metal particle type raw material comprises a metal selected from the group consisting of: titanium, zirconium, hafnium, nickel, stainless steel and combinations thereof.

11. The composition according to claim 10, further comprising a binder and a dispersant, such that the composition comprises: 21.3 to 56.8 wt% of the metal fiber-type raw material relative to the total weight of the composition; 14.2 to 49.7 wt % of the metal particle-type raw material relative to the total weight of the composition; 0.1 to 4 wt % of the binder relative to the total weight of the composition; and 0.1 to 3 wt% of the dispersant relative to the total weight of the composition.

12. The composition according to claim 11, wherein the dispersant comprises one selected from the group consisting of water, ethanol, methanol, isopropanol, xylene, cyclohexanone, acetone, methyl ethyl ketone, and combinations thereof. 13 . The composition according to claim 11 , wherein the binder comprises a material that is thermally degradable at a temperature of 500° C. or less while allowing adhesive strength between metal components to be maintained.

14. The composition of claim 13, wherein the binder comprises one selected from the group consisting of polyvinyl butyral, polyvinyl alcohol, polyvinyl chloride, polyvinyl acetate, polyacrylonitrile, and combinations thereof.

15. A method of forming the porous transport layer of claim 1, the method comprising: (a) removing fat from the composition of claim 10 by a defatting process at a predetermined temperature; as well as (b) sintering the resulting product obtained in (a).

16. The method according to claim 15, wherein (a) further comprises a process of shaping the composition.

17. The method according to claim 15, wherein the degreasing process in (a) is performed at the predetermined temperature of 300°C to 700°C.

18. The method according to claim 17, wherein: The degreasing process in a) is performed by increasing the temperature to the predetermined temperature at a heating rate of 1° C. / min to 3° C. / min and maintaining the same temperature for 1 to 5 hours.

19. The method according to claim 15, wherein: At temperatures between 900°C and 1400°C and 10 -5 The sintering in (b) is performed at a vacuum level of 200 torr or less.

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