Porous structure, apparatus, and method for manufacturing a porous structure

Abstract

To provide a porous structure that can achieve good flow path performance. [Solution] The porous structure 1 is a porous structure produced by heat-treating a polymer structure, and at least a part of it has a periodic structure in which the beam structure 1c is periodically repeated.

Description

Technical Field

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[0001] The present invention relates to a porous structure, an apparatus, and a method for manufacturing a porous structure.

Background Art

[0002] In an apparatus using a porous structure as a flow path (e.g., a gas diffusion layer), the flow path performance affects the performance and output of the apparatus. Therefore, a porous structure capable of obtaining good flow path performance is desired.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The problem to be solved by the present invention is to provide a porous structure capable of obtaining good flow path performance.

Means for Solving the Problems

[0005] [1] The porous structure according to one aspect of the present invention is a porous structure produced by heat-treating a polymer structure, and at least a part thereof has a periodic structure in which a beam structure is periodically repeated. <00000�4> [2] The porous structure according to one aspect of the present invention is the porous structure described in [1] above, wherein the beam structure includes pore portions.

[0007] [3] The porous structure according to one aspect of the present invention is the porous structure described in [2] above, wherein the shape of the pore portions is different in a first direction and a second direction different from the first direction.

[0008] [4] A porous structure according to one aspect of the present invention is a porous structure according to any of the above [2] to [3], The fluid pressure loss differs between the first and second directions.

[0009] [5] A porous structure according to one aspect of the present invention is a porous structure according to any of the above [2] to [4], The aforementioned holes are formed such that their diameter increases in the direction of bubble discharge.

[0010] [6] A porous structure according to one aspect of the present invention is a porous structure according to any of the above [1] to [5], The polymer structure is formed by stereolithography using photoresin as the starting material.

[0011] [7] A porous structure according to one aspect of the present invention is a porous structure according to any of the above [1] to [6], The polymer structure is a gel structure.

[0012] [8] A porous structure according to one aspect of the present invention is a porous structure according to any of the above [1] to [7], It contains carbon as a constituent material.

[0013] [9] A porous structure according to one aspect of the present invention is a porous structure described in [8] above, It further contains inorganic materials other than carbon as constituent materials.

[0014]

[10] A porous structure according to one aspect of the present invention is a porous structure described in [9] above, The inorganic material includes a metal, a metal ion, or an organometallic compound.

[0015]

[11] A porous structure according to one aspect of the present invention is a porous structure according to any of the above [8] to

[10] , The carbon content is, It is 0.1 wt% or more and 5 wt% or less.

[0016]

[12] The porous structure according to one aspect of the present invention is the porous structure according to any one of [8] to

[11] above, contains the carbon as a metal carbide, and the content of the carbon is, 3 wt% or more and 40 wt% or less.

[0017]

[13] The porous structure according to one aspect of the present invention is the porous structure according to any one of [1] to

[12] above, The porosity is 20% or more and 99% or less.

[0018]

[14] The porous structure according to one aspect of the present invention is the porous structure according to any one of [1] to

[13] above, The surface roughness Ra of the inner wall is 50 μm or less.

[0019]

[15] The apparatus according to one aspect of the present invention includes the porous structure according to any one of [1] to

[14] above.

[0020]

[16] The apparatus according to one aspect of the present invention is the apparatus according to

[15] above, and includes the porous structure as a gas diffusion layer of an electrolytic cell.

[0021]

[17] The apparatus according to one aspect of the present invention is the apparatus according to

[15] above, and includes the porous structure as a gas diffusion layer or a proton transport layer of a fuel cell.

[0022]

[18] The manufacturing method according to one aspect of the present invention is, a manufacturing method of a porous structure having at least a part of a periodic structure in which a beam structure is periodically repeated, a step of molding a polymer structure as a prototype of the porous structure by stereolithography using a photoresin as a starting material, a step of heat-treating the polymer structure, and includes.

[0023]

[19] A manufacturing method according to one aspect of the present invention is the manufacturing method described in

[18] above, The polymer structure includes inorganic materials other than carbon.

[0024]

[20] A method for manufacturing a porous structure according to one aspect of the present invention is the manufacturing method described in

[19] above, The inorganic material includes a metal, a metal ion, or an organometallic compound.

[0025]

[21] A manufacturing method according to one aspect of the present invention is the manufacturing method described in any of

[18] to

[20] above, The aforementioned heat treatment step includes a firing step.

[0026]

[22] A manufacturing method according to one aspect of the present invention is, in the manufacturing method described in any of the above

[21] , The heat treatment step further includes a reduction step after the firing step.

[0027]

[23] A manufacturing method according to one aspect of the present invention is the manufacturing method described in any of

[18] to

[22] above, The polymer structure has different shapes for the holes included in the beam structure in a first direction and in a second direction different from the first direction.

[0028]

[24] A manufacturing method according to one aspect of the present invention is a manufacturing method described in any of

[18] to

[23] above, The polymer structure is a gel structure. [Effects of the Invention]

[0029] According to one aspect of the present invention, it is possible to provide a porous structure having a three-dimensional structure that can obtain good performance for electrochemical devices. [Brief explanation of the drawing]

[0030] [Figure 1] This is a schematic cross-sectional view of a water electrolysis apparatus using a porous structure according to this embodiment. [Figure 2A] This figure shows an example of a three-dimensional structure of a porous structure according to this embodiment. [Figure 2B] This is an enlarged view of the beam structure that constitutes the porous structure according to this embodiment. [Figure 3] This figure shows the conditional expression that the porous structure according to this embodiment satisfies. [Figure 4] This figure shows an example of the manufacturing process for a porous structure according to this embodiment. [Figure 5] This figure shows an example of a method for manufacturing a porous structure according to this embodiment. [Figure 6] This is a schematic cross-sectional view of a fuel cell using a porous structure according to this embodiment. [Figure 7] This figure shows another example of the manufacturing process for a porous structure according to this embodiment. [Figure 8] This figure shows another example of a method for manufacturing a porous structure according to this embodiment. [Figure 9] This figure shows another example of the manufacturing process for a porous structure according to this embodiment. [Figure 10] This figure shows another example of a method for manufacturing a porous structure according to this embodiment. [Figure 11] This figure shows an example of the arrangement of the porous structure of this embodiment with the small pore side facing the flow path direction (small pore arrangement). [Figure 12] This figure shows an example of the arrangement of the porous structure of this embodiment with the large pore side facing the flow path direction (large pore arrangement). [Figure 13] This figure shows the relationship between the average flow velocity at the channel inlet and the pressure loss per unit length of the porous structure when the beam diameter is 200 μm. [Figure 14] This figure shows the relationship between the average flow velocity at the channel inlet and the pressure loss per unit length of the porous structure when the beam diameter is 20 μm. [Modes for carrying out the invention]

[0031] The following descriptions of each embodiment will be made with reference to the drawings. However, unnecessarily detailed explanations may be omitted. For example, detailed explanations of already well-known matters and redundant explanations of substantially identical configurations may be omitted. This is to avoid the following explanation becoming unnecessarily verbose and to facilitate understanding for those skilled in the art.

[0032] The porous structure 1 according to this embodiment can be used in devices through which a fluid (gas, liquid, etc.) is passed, and a portion of the fluid conducts heat transfer or surface reactions on the surface of the porous structure 1. Specifically, the porous structure 1 can be used, for example, as an electrode in an electrochemical device (e.g., an electrode in a lithium-ion battery), a current collector in an electrochemical device (e.g., a current collector in a lithium metal battery), a fuel cell, a catalyst device, a gas diffusion layer or electrode in an electrolysis device (e.g., electrolysis of carbon dioxide, electrolysis of saline solution, etc.), a heat sink, a wick for a vapor chamber, a catalyst or catalyst support material for various sensors, etc. An example of a device using the porous structure 1 will be described below. <First Embodiment>

[0033] (Water electrolysis device) Figure 1 is a schematic cross-sectional view showing the general configuration of a water electrolysis apparatus 100 using the porous structure 1 according to this embodiment. As shown in Figure 1, the water electrolysis apparatus 100 has a water electrolysis cell 10. This water electrolysis cell 10 comprises an anode 3A consisting of a porous structure 1A and an anode catalyst layer 2A, and a cathode 3C consisting of a porous structure 1C and a cathode catalyst layer 2C. In the water electrolysis cell 10, the porous structure 1 (1A, 1C) functions as a gas diffusion layer (GDL). The structure of the porous structure 1 will be described later.

[0034] An electrolyte membrane 4 is placed between the anode 3A and the cathode 3C. Separators 5A and 5C are placed outside the anode 3A and cathode 3C, respectively, and a voltage is applied from the power supply 6 to the anode 3A and cathode 3C via these separators 5A and 5C. Gaskets 7 and 8 are placed between separator 5A and the electrolyte membrane 4, and between separator 5C and the electrolyte membrane 4, respectively.

[0035] Water (H2O) is supplied to the water electrolysis cell 10 from the water supply unit 9a. Oxygen (O2) generated at the anode 3A is exhausted from the oxygen exhaust unit 9b, and hydrogen (H2) generated at the cathode 3C is exhausted from the hydrogen exhaust unit 9c. Although Figure 1 shows an example in which the water electrolysis apparatus 100 has one water electrolysis cell 10, the water electrolysis apparatus 100 may have multiple stacked water electrolysis cells 10. The water supply unit 9a may be provided on the anode side (separator 5A), or on both the anode side (separator 5A) and the cathode side (separator 5C).

[0036] (Porous structure) Next, we will describe the porous structure 1 (1A, 1C).

[0037] Figure 2 is a schematic diagram showing the three-dimensional structure of porous structure 1, specifically a portion of porous structure 1 that has been cut out. The three-dimensional data of this porous structure 1 is created using 3D CAD (Computer-Aided Design).

[0038] As shown in Figure 2A, the porous structure 1 has a beam structure 1c that includes numerous pores 1a through which the gas generated in the water electrolysis cell 10 can pass, and pores 1b that are larger than pores 1a. The pores (pores 1a and pores 1b) of this beam structure 1c form flow channels inside the porous structure 1.

[0039] Figure 2B is an enlarged view of the beam structure 1c that constitutes the porous structure 1. As shown in Figure 2B, the beam structure 1c is composed of multiple beams B. The beam structure 1c is, for example, an FCCZ (face-centered cubic with vertical struts) structure. This beam structure 1c forms a periodic structure (for example, an octet truss structure) that is continuously and periodically repeated in three dimensions inside the porous structure 1. Compared to a random structure, this periodic structure is expected to result in a more uniform fluid, making it possible to reduce fluid shear stress.

[0040] Furthermore, by changing the spacing of beams B on the surface of the porous structure 1, the wettability to liquids such as water can be controlled. For example, by changing the spacing of beams B, it is possible to control whether or not water droplets enter the interior of the porous structure 1.

[0041] Furthermore, the periodic structure of the beam structure 1c facilitates the detachment of air bubbles attached to the porous structure 1 and makes it less likely for air bubbles to be trapped (attached) inside the porous structure 1. As a result, the efficiency of air bubble transport through the porous structure 1 can be increased. Note that this periodic structure only needs to be formed in at least a part of the porous structure 1.

[0042] Furthermore, as shown in Figure 2A, when the porous structure 1 is viewed from the X or Y direction, the pore portion 1a (small pore) faces forward, but when viewed from the Z direction, the pore portion 1b (large pore) faces forward. Thus, the porous structure 1 has an anisotropy in which the shape of the pore portion viewed from the X direction is the same as the shape of the pore portion viewed from the Y direction, but the shape of the pore portion viewed from the Z direction (first direction) is different from the shape of the pore portion viewed from the X or Y direction (second direction). As a result, when a fluid is flowed through the porous structure 1, anisotropy of pressure loss occurs depending on the direction of the porous structure 1. This anisotropy of pressure loss makes it possible to promote reactions or improve efficiency in devices where the direction of fluid supply / discharge and the direction of the reaction field are different, such as diffusion layers and electrodes in water electrolysis and fuel cells.

[0043] Here, we will explain the anisotropy of fluid pressure loss due to the anisotropy of the pore shape of the porous structure 1 using simulation results.

[0044] Figure 11 shows an example of a porous structure 1 (3D model) being placed inside a cylindrical tube with the small holes (hole 1a) facing the flow direction (small hole arrangement). Figure 12 shows an example of a porous structure 1 (3D model) being placed inside a cylindrical tube with the large holes (hole 1b) facing the flow direction (large hole arrangement). Figure 13 shows the simulation results of the relationship between the average inlet velocity of a fluid (water, for example) and the pressure loss per unit length of the porous structure for a beam diameter of 200 μm (length of one side of the porous structure 1: 3 mm, length of the cylindrical tube: 10 mm). Figure 14 shows the simulation results of the relationship between the average inlet velocity of a fluid (water, for example) and the pressure loss per unit length of the porous structure for a beam diameter of 20 μm (length of one side of the porous structure 1: 0.3 mm, length of the cylindrical tube: 1 mm). As shown in Figures 13 and 14, the pressure loss per unit length of the flow path can be increased when the porous structure 1 is arranged with small holes (Figure 11) compared to when the porous structure 1 is arranged with large holes (Figure 12). Note that Figures 13 and 14 show the case where the fluid is water as an example, but similar trends can be obtained with other fluids (liquids, gases).

[0045] Furthermore, the beam structure 1c of the porous structure 1 may be formed such that its size (pore diameter and flow path width) increases in the direction of fluid (bubble) discharge. That is, as shown in Figure 2A, the beam structure 1c may be formed such that the pore diameter d2 on the fluid (bubble) discharge side (separator side) is larger than the pore diameter d1 on the fluid (bubble) supply side (electrolyte membrane side). This allows bubbles taken into the porous structure 1 to be smoothly discharged to the outside, improving the flow path performance of the porous structure. As a result, the performance of the device (e.g., an electrochemical device) can be improved.

[0046] Furthermore, if the pore diameter (hole 1a and hole 1b) is too small, the resistance applied to the fluid increases, slowing down the fluid supply speed. Conversely, if the pore diameter is too large, the contact surface between the bubbles and the porous structure does not increase easily, requiring larger bubbles to detach, and thus taking longer for the bubbles to detach. For this reason, it is preferable that the pore diameter be formed to be between 1 μm and 100 μm. More preferably, the lower limit of the pore diameter is 10 μm or more. Specifically, it is preferable that the pore diameter included in the first and second layers of the periodic structure, counting from the fluid supply side of the porous structure 1, be between 20 μm and 30 μm.

[0047] Furthermore, it is preferable to set the pore diameter to satisfy the condition shown in Figure 3. By satisfying the condition shown in Figure 3, bubbles can pass through the pores more easily. This makes it possible to improve the bubble discharge efficiency of the porous structure 1.

[0048] Furthermore, if the porosity of the porous structure 1 is too low, the pressure loss of the fluid flowing inside the porous structure 1 will increase, and if it is too high, the mechanical strength of the porous structure 1 will decrease. For this reason, the porosity is preferably between 20% and 99%. Moreover, it is more preferable that the porosity is between 80% and 95%.

[0049] Furthermore, if the surface roughness Ra of the porous structure 1 is too high, the pressure loss of the fluid flowing inside the porous structure 1 will increase, so it is preferable that it be 50 μm or less. It is more preferable that the surface roughness Ra be 1 μm or less.

[0050] Materials that can be used to constitute the porous structure include carbon, inorganic materials, metals, metal alloys, metal carbides, oxides, nitrides, organometallic compounds, and composite materials obtained by mixing these materials. Furthermore, the composite material may have a core-shell structure.

[0051] Materials that make up porous structures include, for example, lithium (Li), sodium (Na), magnesium (Mg), aluminum (Al), silicon (Si), sulfur (S), potassium (K), calcium (Ca), scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), gallium (Ga), germanium (Ge), arsenic (As), strontium (Sr), yttrium (Y), and zirconium (Z). r), niobium (Nb), molybdenum (Mo), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), cadmium (Cd), indium (In), tin (Sn), (Sb), barium (Ba), hafnium (Hf), tantalum (Ta), tungsten (W), rhenium (Re), osmium (Os), iridium (Ir), platinum (Pt), gold (Au), mercury (Hg), titanium (Ti), lead (Pb), bismuth (Bi), polonium (Po), neodymium (Nd), and ytterbium (Yb) may also be used.

[0052] The carbon (C) content as an impurity in the porous structure 1 is preferably 5 wt% or less. This increases the mechanical strength of the porous structure 1. On the other hand, if it is too low, the mechanical properties will decrease, and if it is too high, the electrical conductivity and thermal conductivity will decrease, affecting the performance of the device (electrochemical device). Therefore, the carbon content as an impurity is preferably 0.1 wt% to 5 wt%, more preferably 0.1 wt% to 1%, or 1 wt% to 5 wt%. In this way, by including carbon as an impurity in the porous structure 1, the mechanical strength can be increased while maintaining electrical conductivity and thermal conductivity.

[0053] Furthermore, when carbon (C) is included as a metal carbide (for example, tungsten carbide (WC), titanium carbide (TiC), etc.), the amount is preferably 3 wt% to 40 wt%, and more preferably 6 wt% to 20 wt%.

[0054] (Method for manufacturing porous structures) First, we will explain the general flow of the manufacturing process for porous structure 1.

[0055] Figure 4 shows an example of the manufacturing process for porous structure 1. As shown in Figure 4, first, a photoresin solution, which is a homogeneous solution of a photosensitive binder, is prepared as the starting material (Figure 4(A)).

[0056] Next, a three-dimensional organogel, which will serve as the template for porous structure 1, is 3D printed (additive-built) into a photoresin solution using photolithography (Figure 4(B)). A polymer gel network is formed inside this organogel. For photolithography, DLP (Digital Light Processing) or SLA (Stereolithography Apparatus) can be used. UV-curing resin (photo-radical polymerization) can be used as the photoresin.

[0057] Next, the organogel is converted into a hydrogel, and the metal precursor (metal ion) is incorporated into the three-dimensional structure of the hydrogel by swelling (Figure 4(C)).

[0058] Next, a three-dimensional hydrogel structure containing a metal precursor (metal ion) is calcined to obtain a three-dimensional structure made of a metal oxide (Figure 4(D)).

[0059] Then, by reducing the three-dimensional structure made of metal oxide after firing, a porous structure 1 made of the desired metal or alloy is obtained (Figure 4(E)).

[0060] Thus, the porous structure 1 is obtained by calcining and reducing a hydrogel structure containing a metal precursor.

[0061] Next, we will specifically describe the manufacturing method of the porous structure 1.

[0062] Figure 5 is a flowchart showing an example of a method for manufacturing the porous structure 1.

[0063] [Preparation of photoresin solution] As shown in Figure 5, first, a photoresin solution (photocurable resin solution) to be used for stereolithography is prepared (see step S1 in Figure 5 / Figure 4(A)).

[0064] Specifically, for example, 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholine-4-ylphenyl)-butan-1-one (Irgacure 379; iGM Resins), bis[4-(dimethylamino)phenyl]methanone (Michler's ketone; Sigma-Aldrich), and 1-(phenyldiazenyl)naphthalene-2-ol (Sudan I; Sigma-Aldrich) are added to DMF (Sigma-Aldrich, >99.9%) and stirred. Then, this solution is added to a mixture of DMF and PEGda Mn = 575 (Sigma-Aldrich), and the solution, after homogenization, can be used as a photoresin solution.

[0065] [3D printing using stereolithography] Next, the photoresin solution is molded into a three-dimensional organogel structure by stereolithography (see step S2 in Figure 5 / Figure 4(B)). This three-dimensional structure corresponds to the three-dimensional structure of porous structure 1 and serves as a scaffold for introducing the metal precursor in a later step (step S4).

[0066] Specifically, for example, based on the three-dimensional data of the porous structure 1 explained in Figure 2, a DLP 3D printer with a wavelength of 405 nm is used to mold a photoresin solution into an organogel (gel structure) of a three-dimensional structure corresponding to the porous structure 1. Here, a gel structure is a polymer structure containing a solvent.

[0067] [Conversion from organogel to hydrogel] Next, the process is converted from organogel to hydrogel by changing the solvent (see step S3 in Figure 5 / Figure 4(C)). This removes the DMF (photoresin component) remaining in the three-dimensional structure, allowing for a uniform distribution of the metal precursor when it is introduced in a later step (step S4).

[0068] Specifically, for example, a 3D-printed organogel is immersed in DMF on a 70°C hot plate for one hour. After the first DMF rinse, the DMF is decanted, and the organic gel is immersed again in fresh DMF at 70°C for one hour. Then, the organogel is immersed in deionized water at 70°C for one hour, followed by immersion in fresh deionized water at 70°C for one hour, converting the three-dimensional structure from an organogel to a hydrogel. This hydrogel is also a gel structure (polymer structure).

[0069] [Introduction of metal precursor] Next, the hydrogel is swollen in a metal salt solution to introduce a metal precursor (metal ion) into the three-dimensional structure (gel structure) of the hydrogel (step S4 in Figure 5 / Figure 4(C)).

[0070] Specifically, for example, a 2M solution of copper nitrate, nickel nitrate, iron nitrate, cobalt nitrate, silver nitrate, chromium nitrate, or ammonium metatungstate is prepared with deionized water, and the three-dimensional hydrogel structure is immersed in the desired metal salt solution at 70°C for 24 hours, or at 70°C for 2 weeks (in the case of a tungsten-nickel alloy). This causes metal ions to precipitate on the three-dimensional hydrogel structure.

[0071] The metal precursor (metal ion) may be pre-mixed into the photoresin solution in step S1. In that case, since the metal precursor is already present in the organogel in step S2, step S4 may be omitted.

[0072] [Firing] Next, the three-dimensional structure (gel structure) of the hydrogel containing the metal precursor (metal ions) is calcined (step S5) to remove the gel component. The calcined three-dimensional structure is composed of metal oxides (see Figure 4(D)).

[0073] Specifically, for example, a three-dimensional hydrogel structure containing a metal precursor (metal ion) is fired in an airflow under low pressure.

[0074] [reduction] Then, the three-dimensional structure (metal oxide structure) composed of metal oxides after firing is reduced (step S6).

[0075] Specifically, for example, the three-dimensional structure after firing is then heated in a forming gas at a flow rate of 150 sccm, a pressure of approximately 22 Torr, and 3°C per minute to 900°C or 700°C (for Cu and Ag), and then reduced by isothermal holding for 6 hours. This yields a porous structure 1 made of the desired metal or alloy (see Figure 4(E)).

[0076] In conventional manufacturing methods, attempts to increase the porosity of porous structures resulted in very low mechanical strength and high surface roughness due to weak sintering between metal powders. On the other hand, according to the manufacturing method of the porous structure 1 of this embodiment, carbon is included as an impurity in the final porous structure 1, making it possible to increase porosity without reducing mechanical strength and also reduce surface roughness.

[0077] As shown in Figure 7, a porous structure 1 consisting of a composite material or carbide (a mixture of metal and carbon) of carbon and reduced metal can be produced by heat treatment under vacuum without firing the hydrogel (gel structure) containing metal ions. In other words, as shown in Figure 8, a porous structure 1 consisting of a mixture of metal and carbon can be produced by performing a heat treatment step (step S51) of the hydrogel (gel structure) after the step of introducing a metal precursor into the hydrogel (step S4).

[0078] Furthermore, as shown in Figure 9, a porous structure 1 made of carbon can be fabricated by heat-treating (including thermal decomposition) the organogel (gel structure) under vacuum. That is, as shown in Figure 10, a porous structure 1 made of carbon can be fabricated by performing a heat-treating step (step S31) of the organogel (gel structure) after the step (step S2) of molding a three-dimensional organogel structure (gel structure) by stereolithography 3D printing.

[0079] Furthermore, although an example of using a gel structure (a polymer structure containing a solvent) as the polymer structure has been described, a polymer structure without a solvent may also be used. That is, a porous structure 1 may be produced by heat-treating a polymer structure without a solvent. <Second Embodiment> Next, a second embodiment will be described, which is an example in which the porous structure 1 is used in a fuel cell. The same reference numerals are used for components similar to those in the first embodiment, and redundant explanations are omitted.

[0080] Figure 6 shows an example of a schematic configuration of a fuel cell 200 according to the second embodiment. As shown in Figure 6, the fuel cell 200 has a fuel cell cell 20. This fuel cell cell 20 comprises a fuel electrode (anode) 13A consisting of a porous structure 1A and an anode catalyst layer 2A, and an oxygen electrode (cathode) 13C consisting of a porous structure 1C and a cathode catalyst layer 2C. In the fuel cell cell 20, the porous structure 1 (1A, 1C) functions as a porous transport layer (PTL) or a gas diffusion layer.

[0081] An electrolyte membrane 4 is placed between the fuel electrode 13A and the oxygen electrode 13C. Separators 5A and 5C are placed outside the fuel electrode 13A and the oxygen electrode 13C, respectively. Gaskets 7 and 8 are placed between separator 5A and the electrolyte membrane 4, and between separator 5C and the electrolyte membrane 4, respectively.

[0082] The fuel cell 20 is supplied with hydrogen from the hydrogen supply unit 120 and oxygen from the oxygen supply unit 121. The water (H2O) produced by the reaction of hydrogen ions and oxygen ions that have moved from the fuel electrode 13A to the oxygen electrode 13C is discharged from the discharge unit 119. Although Figure 6 shows an example in which the fuel cell 200 has one fuel cell 20, the fuel cell 200 may have multiple stacked fuel cell cells 20.

[0083] Thus, the fuel cell according to the second embodiment uses a porous structure 1 with excellent gas (bubble) permeability as the porous transport layer of the fuel cell cell 20, thereby increasing the reaction efficiency of the oxidation-reduction reaction that occurs in the fuel cell cell 20.

[0084] As described above, the present invention is not limited to the embodiments described above, and the components can be modified and implemented in practice without departing from the spirit of the invention. Furthermore, various inventions can be formed by appropriately combining the multiple components disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiments. Moreover, components from different embodiments may be appropriately combined. [Explanation of symbols]

[0085] 1 Porous structure 10 Water electrolysis cell 20 fuel cell cells 100 Water electrolysis equipment 200 Fuel Cell

Claims

1. A porous structure produced by heat-treating a polymer structure, The beam structure has at least a portion of a periodic structure in which it repeats periodically. Porous structure.

2. The porous structure according to claim 1, wherein the beam structure includes a hole.

3. The porous structure according to claim 2, wherein the shape of the pores differs in a first direction and in a second direction different from the first direction.

4. The porous structure according to claim 3, wherein the fluid pressure loss differs in the first direction and the second direction.

5. The porous structure according to claim 2, wherein the pores are formed such that the diameter of the pores increases in the direction of bubble discharge.

6. The polymer structure is formed by stereolithography using photoresin as the starting material. A porous structure according to any one of claims 1 to 5.

7. The polymer structure is a gel structure. The porous structure according to claim 6.

8. A porous structure according to claim 1, comprising carbon as a constituent material.

9. The porous structure according to claim 8, further containing an inorganic material other than carbon as a constituent material.

10. The porous structure according to claim 9, wherein the inorganic material comprises a metal, a metal ion, or an organometallic compound.

11. The carbon content is, It is between 0.1 wt% and 5 wt%. The porous structure according to claim 10.

12. The material contains carbon as a metal carbide, and the carbon content is It is between 3 wt% and 40 wt%. The porous structure according to claim 10 or 11.

13. The porosity is between 20% and 99%. The porous structure according to claim 1.

14. The surface roughness Ra of the inner wall is 50 μm or less. The porous structure according to claim 1.

15. An apparatus comprising the porous structure described in claim 1.

16. The porous structure is provided as the gas diffusion layer of the electrolytic cell. The apparatus according to claim 15.

17. The porous structure is provided as the gas diffusion layer or proton transport layer of the fuel cell. The apparatus according to claim 15.

18. A method for manufacturing a porous structure having at least a portion of a periodic structure in which the beam structure is periodically repeated, A step of molding a polymer structure that will serve as the prototype for the porous structure by photopolymerization using photoresin as the starting material, A step of heat-treating the polymer structure, A method for manufacturing a porous structure, including [the specified element].

19. The aforementioned polymer structure includes inorganic materials other than carbon. A method for manufacturing a porous structure according to claim 18.

20. The inorganic material includes a metal, a metal ion, or an organometallic compound. A method for manufacturing a porous structure according to claim 19.

21. The heat treatment step includes a firing step. A method for manufacturing a porous structure according to claim 18.

22. The heat treatment step further includes a reduction step after the firing step. A method for manufacturing a porous structure according to claim 21.

23. A method for manufacturing a porous structure according to any one of claims 18 to 22, wherein the polymer structure has different shapes of pores in the beam structure in a first direction and in a second direction different from the first direction.

24. The polymer structure is a gel structure. A method for manufacturing a porous structure according to claim 23.

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