Framed membrane-electrode structure

Abstract

To provide a membrane-electrode structure with a frame that can prevent the intrusion of dust and the decrease in the efficiency of the electrochemical reaction in a membrane-electrode structure.SOLUTION: A membrane-electrode structure 10 with a frame includes a membrane-electrode assembly 20 and a resin frame sheet member 30. A first electrode 22 and a second electrode 23 of the membrane-electrode assembly 20 extend outwardly toward the frame sheet member 30 beyond the outer circumferential end 21e of an electrolyte membrane 21 along their entire peripheries. The outer circumferential portion 22PT of the first electrode 22 is joined to one surface 30f1 of the frame sheet member 30 along its entire periphery. The outer circumferential portion 23PT of the second electrode 23 is joined to the other surface 30f2 of the frame sheet member 30 along its entire periphery.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a framed membrane-electrode structure. [Background technology]

[0002] In recent years, research and development into fuel cells has been conducted to contribute to energy efficiency, ensuring that more people have access to affordable, reliable, sustainable and advanced energy.

[0003] A fuel cell includes a membrane electrode assembly (MEA). Patent Document 1 discloses a framed membrane electrode assembly. The framed membrane electrode assembly includes a membrane electrode assembly and a frame member having a resin sheet. The membrane electrode assembly is a structure including an electrolyte membrane, a first electrode, and a second electrode. The frame member is provided around the entire outer periphery of the membrane electrode assembly. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7034212 Summary of the Invention [Problem to be solved by the invention]

[0005] However, if dust particles such as iron ions get mixed into the interior of the membrane-electrode assembly from the interface between the membrane-electrode assembly and the resin sheet, the efficiency of the electrochemical reaction in the membrane-electrode assembly tends to decrease. Furthermore, if dust particles get mixed into the interior of the membrane-electrode assembly, the decomposition of the electrolyte membrane tends to accelerate. Therefore, there was a demand for an improvement in the structure of the framed membrane-electrode assembly.

[0006] The present invention aims to solve the above-mentioned problems. [Means for solving the problem]

[0007] An embodiment of the present invention is a framed membrane-electrode structure comprising a membrane-electrode structure including an electrolyte membrane, a first electrode, and a second electrode, and a resin frame sheet member provided around the entire periphery of the membrane-electrode structure, wherein the first electrode and the second electrode extend outward from the outer periphery of the electrolyte membrane toward the frame sheet member around the entire periphery, and the outer periphery of the first electrode is joined to one surface of the frame sheet member around the entire periphery, and the outer periphery of the second electrode is joined to the other surface of the frame sheet member around the entire periphery. [Effects of the Invention]

[0008] According to the aspects of the present invention, it is possible to suppress the inclusion of dust, thereby suppressing a decrease in the efficiency of the electrochemical reaction in the membrane-electrode assembly, and also suppressing deterioration of the electrolyte membrane. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is an exploded perspective view of a main part of a power generating cell according to an embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 3 is a graph showing the relationship between the width of the first junction and the amount of ion penetration. [Figure 4] FIG. 4 is a cross-sectional view taken along line II-II in FIG. 1 according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] 1 is an exploded perspective view of a main part of a power generating cell according to an embodiment. The power generating cell 12 is, for example, a fuel cell such as a polymer electrolyte fuel cell. A plurality of power generating cells 12 are stacked to form a fuel cell stack 11. The fuel cell stack 11 is mounted on a mobile object such as an automobile (not shown).

[0011] The power generating cell 12 includes a framed membrane electrode assembly 10, a first separator 14, and a second separator 16. The framed membrane electrode assembly 10 will be referred to hereinafter as a framed MEA 10. The framed MEA 10 is sandwiched between the first separator 14 and the second separator 16.

[0012] The first separator 14 is made of, for example, a metal plate or a carbon member. Examples of metal plates include steel plates, stainless steel plates, aluminum plates, titanium plates, titanium alloy plates, and plated steel plates. When the first separator 14 is made of a metal plate, the surface of the metal plate may be subjected to a surface treatment for corrosion prevention.

[0013] The second separator 16 is made of, for example, a metal plate or a carbon member. Examples of the metal plate include a steel plate, a stainless steel plate, an aluminum plate, a titanium plate, a titanium alloy plate, and a plated steel plate. When the second separator 16 is made of a metal plate, the surface of the metal plate may be subjected to a surface treatment for corrosion prevention.

[0014] The framed MEA 10, the first separator 14, and the second separator 16 have substantially the same outer shape. Fig. 1 shows an example in which the framed MEA 10, the first separator 14, and the second separator 16 have rectangular outer shapes.

[0015] The framed MEA 10 includes a membrane electrode assembly 20 and a frame sheet member 30. The membrane electrode assembly 20 is referred to as an MEA 20. Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1 .

[0016] The MEA 20 is a structure including an electrolyte membrane 21, a first electrode 22, and a second electrode 23. In addition to the electrolyte membrane 21, the first electrode 22, and the second electrode 23, the MEA 20 also includes a first catalyst layer 24 and a second catalyst layer 25.

[0017] One of the first electrode 22 and the second electrode 23 is an anode electrode. The other of the first electrode 22 and the second electrode 23 is a cathode electrode. In this embodiment, the first electrode 22 is an anode electrode. Therefore, hereinafter, the first electrode 22 will be referred to as an anode electrode 22. Also, in this embodiment, the second electrode 23 is a cathode electrode. Therefore, hereinafter, the second electrode 23 will be referred to as a cathode electrode 23.

[0018] The electrolyte membrane 21 is, for example, a solid polymer electrolyte membrane (cation exchange membrane). The solid polymer electrolyte membrane is, for example, a thin film of perfluorosulfonic acid containing water. The electrolyte membrane 21 is sandwiched between an anode electrode 22 and a cathode electrode 23. The electrolyte membrane 21 can be a fluorine-based electrolyte or an HC (hydrocarbon)-based electrolyte.

[0019] The electrolyte membrane 21 has planar dimensions (outer dimensions) smaller than those of the anode electrode 22 and the cathode electrode 23. The outer peripheral edge 21e of the electrolyte membrane 21 is located, over its entire periphery, inside the outer peripheral edge 22e of the anode electrode 22 and the outer peripheral edge 23e of the cathode electrode 23. The outer peripheral edge 21e of the electrolyte membrane 21 is sandwiched between the cathode electrode 23 and the frame sheet member 30 over its entire periphery.

[0020] The anode electrode 22 has a first gas diffusion layer 22a and a first auxiliary diffusion layer 22b, and the cathode electrode 23 has a second gas diffusion layer 23a and a second auxiliary diffusion layer 23b.

[0021] The first gas diffusion layer 22a and the second gas diffusion layer 23a are each formed of, for example, carbon paper or carbon cloth. The first auxiliary diffusion layer 22b and the second auxiliary diffusion layer 23b are each formed of, for example, a composite material of carbon particles and a water-repellent resin. The first auxiliary diffusion layer 22b and the second auxiliary diffusion layer 23b do not necessarily have to be provided.

[0022] The anode electrode 22 and the cathode electrode 23 have planar dimensions (outer dimensions) larger than those of the electrolyte membrane 21. Each of the anode electrode 22 and the cathode electrode 23 extends outward from the outer peripheral edge 21e of the electrolyte membrane 21 along the entire periphery.

[0023] The outer peripheral portion 22PT of the anode electrode 22 is joined to one surface 30f1 of the frame sheet member 30. An end portion of the frame sheet member 30 is sandwiched between the anode electrode 22 and the electrolyte membrane 21. Therefore, the anode electrode 22 has a first inclined portion 22t around the entire periphery. This first inclined portion 22t provides a step in the anode electrode 22. The first inclined portion 22t is located inside the outer peripheral end 21e of the electrolyte membrane 21. The first inclined portion 22t inclines so as to approach the cathode electrode 23 as it moves from the outside to the inside. The first inclined portion 22t approaches the cathode electrode 23 as it moves away from the inner peripheral end 30e of the frame sheet member 30.

[0024] The outer peripheral portion 23PT of the cathode electrode 23 is joined to the other surface 30f2 of the frame sheet member 30. The end of the electrolyte membrane 21 is sandwiched between the cathode electrode 23 and the end of the frame sheet member 30. Therefore, the cathode electrode 23 has a second inclined portion 23t around the entire periphery. This second inclined portion 23t provides a step in the cathode electrode 23. The second inclined portion 23t is located outside the inner peripheral end 30e of the frame sheet member 30. The second inclined portion 23t is located outside the first inclined portion 22t. The second inclined portion 23t is inclined so as to move away from the anode electrode 22 as it moves from the outside to the inside. The second inclined portion 23t moves away from the anode electrode 22 as it approaches the outer peripheral end 21e of the electrolyte membrane 21.

[0025] The width L2 of the second inclined portion 23t in the direction from the outside to the inside of the frame sheet member 30 may be shorter than the width L1 of the first inclined portion 22t in the direction from the outside to the inside of the frame sheet member 30 over the entire periphery. In this case, the inclination of the second inclined portion 23t is steeper than the inclination of the first inclined portion 22t. The total thickness of the electrolyte membrane 21, the first catalyst layer 24, and the second catalyst layer 25 may be equal to or greater than the thickness of the frame sheet member 30.

[0026] Each of the first catalytic layer 24 and the second catalytic layer 25 contains platinum. Each of the first catalytic layer 24 and the second catalytic layer 25 is formed of, for example, porous carbon particles having a platinum alloy supported on the surface. Each of the first catalytic layer 24 and the second catalytic layer 25 has smaller planar dimensions (external dimensions) than the anode electrode 22 and the cathode electrode 23.

[0027] The first catalyst layer 24 is bonded to the surface 21f1 of the electrolyte membrane 21, for example, via an ion-conductive polymer binder. The second catalyst layer 25 is bonded to the surface 21f2 of the electrolyte membrane 21 opposite to the surface 21f1, for example, via an ion-conductive polymer binder.

[0028] The first catalyst layer 24 has smaller planar dimensions (external dimensions) than the second catalyst layer 25. The outer peripheral edge 24e of the first catalyst layer 24 is positioned more inward than the outer peripheral edge 25e of the second catalyst layer 25 along the entire periphery. The outer peripheral edge 24e of the first catalyst layer 24 is positioned between the electrolyte membrane 21 and the frame sheet member 30. The second catalyst layer 25 is laminated over the entire surface of the electrolyte membrane 21. Therefore, the outer peripheral edge 25e of the second catalyst layer 25 extends to the outer peripheral edge 21e of the electrolyte membrane 21. The outer peripheral edge 24e of the first catalyst layer 24 is positioned more inward than the outer peripheral edge 25e of the second catalyst layer 25.

[0029] The frame sheet member 30 is provided around the entire periphery of the outer periphery of the MEA 20. The frame sheet member 30 is a sheet member made of resin. The frame sheet member 30 is formed as a single flat sheet.

[0030] Materials for the frame sheet member 30 include PPS (polyphenylene sulfide), PPA (polyphthalamide), PEN (polyethylene naphthalate), PES (polyethersulfone), LCP (liquid crystal polymer), PVDF (polyvinylidene fluoride), silicone resin, fluororesin, m-PPE (modified polyphenylene ether resin), PET (polyethylene terephthalate), PBT (polybutylene terephthalate), modified polyolefin, etc.

[0031] The thickness of the frame sheet member 30 may be thinner than the thickness of the anode electrode 22, and may be thinner than the thickness of the cathode electrode 23. The inner periphery of the frame sheet member 30 is disposed between the anode electrode 22 and the cathode electrode 23. The inner periphery of the frame sheet member 30 has a first bonding portion 30a and a second bonding portion 30b.

[0032] The first joint portion 30a is a portion joined to each of the anode electrode 22 and the cathode electrode 23. The first joint portion 30a is disposed outward of the second joint portion 30b. The first joint portion 30a does not overlap the electrolyte membrane 21. One surface 30f1 of the first joint portion 30a is joined to the outer periphery 22PT of the anode electrode 22 along the entire periphery. The first joint portion 30a and the outer periphery 22PT of the anode electrode 22 are joined by adhesion or welding. The other surface 30f2 of the first joint portion 30a is joined to the outer periphery 23PT of the cathode electrode 23 along the entire periphery. The first joint portion 30a and the outer periphery 23PT of the cathode electrode 23 are joined by adhesion or welding.

[0033] The second bonding portion 30b is a portion bonded to each of the anode electrode 22 and the electrolyte membrane 21, and is spaced apart from the first bonding portion 30a. The second bonding portion 30b is located more inward than the first bonding portion 30a. The second bonding portion 30b overlaps the electrolyte membrane 21. One surface 30f1 of the second bonding portion 30b is bonded to the outer periphery 22PT of the anode electrode 22 around the entire periphery. The second bonding portion 30b and the outer periphery 22PT of the anode electrode 22 are bonded by adhesion or welding.

[0034] The outer side of the other surface 30f2 of the second bonding portion 30b is bonded to the electrolyte membrane 21 along the entire periphery. The inner side of the other surface 30f2 of the second bonding portion 30b is bonded to the first catalyst layer 24 along the entire periphery. The second bonding portion 30b is bonded to the electrolyte membrane 21 and the first catalyst layer 24 by adhesion or welding.

[0035] 3 is a graph showing the relationship between the width L3 (FIG. 2) of the first joint portion 30a and the amount of ion penetration. The width L3 of the first joint portion 30a is the length in the direction from the outside to the inside (plane direction) of the frame sheet member 30. The amount of ion penetration is the amount of ions that reach the inside of the framed MEA 10 (the outer peripheral edge 21e of the electrolyte membrane 21) from the outside. The ions reach the inside of the framed MEA 10 via at least one of the interface between the first joint portion 30a and the anode electrode 22 and the interface between the first joint portion 30a and the cathode electrode 23.

[0036] Experiments have shown that when the width L3 of the first bonding portion 30a is 0.4 mm or greater, the amount of ion penetration is almost zero. Similar results were obtained when the first bonding portion 30a was joined to the anode electrode 22 and the cathode electrode 23 by adhesive bonding and when the first bonding portion 30a was joined to the anode electrode 22 and the cathode electrode 23 by welding.

[0037] In this way, in the framed MEA 10, an encapsulation section is formed by sandwiching the frame sheet member 30 between the anode electrode 22 and the cathode electrode 23. The end of the frame sheet member 30 and the end of the electrolyte membrane 21 are positioned offset toward the inside of the framed MEA 10 from the encapsulation section. Therefore, the frame sheet member 30 included in the encapsulation section can be formed from a single sheet, allowing the framed MEA 10 to be made thinner.

[0038] Next, the flow path structure of the power generation cell 12 will be described. As shown in Fig. 1, an oxidant gas inlet manifold 40a, a coolant inlet manifold 42a, and a fuel gas outlet manifold 44b are provided at one end edge of the power generation cell 12 in the direction of arrow B (horizontal direction), and are connected to each other in the direction of arrow A, which is the stacking direction. The oxidant gas inlet manifold 40a supplies an oxidant gas, for example, an oxygen-containing gas. The coolant inlet manifold 42a supplies a coolant. The fuel gas outlet manifold 44b discharges a fuel gas, for example, a hydrogen-containing gas. The oxidant gas inlet manifold 40a, the coolant inlet manifold 42a, and the fuel gas outlet manifold 44b are arranged in the direction of arrow C (vertical direction).

[0039] A fuel gas inlet manifold 44a for supplying fuel gas, a coolant outlet manifold 42b for discharging the coolant, and an oxidant gas outlet manifold 40b for discharging the oxidant gas are provided at the other end edge of the power-generating cell 12 in the direction of arrow B. These manifolds communicate with each other in the direction of arrow A. The fuel gas inlet manifold 44a, the coolant outlet manifold 42b, and the oxidant gas outlet manifold 40b are arranged in the direction of arrow C.

[0040] A fuel gas flow field 46 communicating with the fuel gas inlet manifold 44a and the fuel gas outlet manifold 44b is provided on the surface 14a of the first separator 14 facing the framed MEA 10. Specifically, the fuel gas flow field 46 is formed between the first separator 14 and the framed MEA 10. The fuel gas flow field 46 has a plurality of linear flow grooves (or wavy flow grooves) extending in the direction of arrow B.

[0041] An oxidant gas flow field 48 communicating with the oxidant gas supply passage 40a and the oxidant gas discharge passage 40b is provided on a surface 16a of the second separator 16 facing the framed MEA 10. Specifically, the oxidant gas flow field 48 is formed between the second separator 16 and the framed MEA 10. The oxidant gas flow field 48 has a plurality of straight flow grooves (or wavy flow grooves) extending in the direction of arrow B.

[0042] A coolant flow field 50 communicating with the coolant inlet passage 42a and the coolant outlet passage 42b is formed between the adjacent surfaces 14b of the first separator 14 and 16b of the second separator 16, extending in the direction of arrow B.

[0043] A surface 14a of the first separator 14 (the surface facing the framed MEA 10) is provided with a plurality of protrusions 52 that form the fuel gas flow path 46. The protrusions 52 bulge toward the anode electrode 22 and abut against the anode electrode 22. A surface 16a of the second separator 16 (the surface facing the framed MEA 10) is provided with a plurality of protrusions 54 that form the oxidant gas flow path 48. The protrusions 54 bulge toward the cathode electrode 23 and abut against the cathode electrode 23. The MEA 20 is sandwiched between the protrusions 52, 54.

[0044] To prevent fuel gas from leaking to the outside, one or more bead seals 56 are provided on the surface 14a of the first separator 14 and surround the outer periphery of the first separator 14. The bead seals 56 are press-molded to expand toward the frame sheet member 30. The inner bead seal 56 surrounds the fuel gas flow field 46, the fuel gas inlet manifold 44a, and the fuel gas outlet manifold 44b, and connects them together.

[0045] A first seal member is fixed to the tip surface of the convex portion of the bead seal 56 by printing, coating, or the like. The bead seal 56 abuts airtight and liquidtightly against the frame sheet member 30 via the first seal member. The first seal member may be fixed to the frame sheet member 30.

[0046] Instead of the bead seal 56, the first separator 14 may be provided with a convex seal portion made of an elastic material that protrudes toward the frame sheet member 30.

[0047] One or more bead seals 58 are provided on the surface 16a of the second separator 16, surrounding the outer periphery of the second separator 16, to prevent the oxidant gas from leaking to the outside. The bead seals 58 are formed by press molding so as to bulge toward the frame sheet member 30. The inner bead seal 58 surrounds the oxidant gas flow field 48, the oxidant gas inlet manifold 40a, and the oxidant gas outlet manifold 40b, and connects them together.

[0048] A second seal member is fixed to the tip surface of the convex portion of the bead seal 58 by printing, coating, or the like. The bead seal 58 abuts airtight and liquidtightly against the frame sheet member 30 via the second seal member. The second seal member may be fixed to the frame sheet member 30.

[0049] The second separator 16 may be provided with a convex seal portion made of an elastic material that protrudes toward the frame sheet member 30, instead of the bead seal 58.

[0050] The first seal member or the second seal member may be made of, for example, polyester fiber, silicone, EPDM, FKM, or the like. The first seal member or the second seal member is not essential and may be omitted. If the first seal member is not present, the bead seal 56 directly abuts against the frame sheet member 30. If the second seal member is not present, the bead seal 58 directly abuts against the frame sheet member 30.

[0051] The bead seals 56 and 58 sandwich the frame sheet member 30. The outer periphery of the frame sheet member 30 is sandwiched between the bead seal 56 of the first separator 14 and the bead seal 58 of the second separator 16. If the first separator 14 and the second separator 16 are provided with the above-mentioned convex seal portion, the outer periphery of the frame sheet member 30 is sandwiched between the convex seal portion of the first separator 14 and the convex seal portion of the second separator 16.

[0052] The operation of the fuel cell stack 11 including the power generating cell 12 configured in this manner will be described below with reference to FIG.

[0053] An oxygen-containing gas or other oxygen-containing gas is supplied to the oxygen-containing gas supply passage 40a, a fuel gas such as a hydrogen-containing gas is supplied to the fuel gas supply passage 44a, and a coolant such as pure water, ethylene glycol, or oil is supplied to the coolant supply passage 42a.

[0054] The oxidant gas is supplied from the oxidant gas inlet manifold 40a to the oxidant gas flow field 48 of the second separator 16, and then travels in the direction of arrow B to be supplied to the cathode 23 of the MEA 20. Meanwhile, the fuel gas is supplied from the fuel gas inlet manifold 44a to the fuel gas flow field 46 of the first separator 14. The fuel gas travels along the fuel gas flow field 46 in the direction of arrow B to be supplied to the anode 22 of the MEA 20.

[0055] In the MEA 20, the oxidant gas supplied to the cathode electrode 23 and the fuel gas supplied to the anode electrode 22 are consumed by electrochemical reactions in the second catalyst layer 25 and the first catalyst layer 24, generating electricity.

[0056] Next, the oxidant gas supplied to and consumed by the cathode 23 is discharged along the oxidant gas discharge passage 40b in the direction of arrow A. Similarly, the fuel gas supplied to and consumed by the anode 22 is discharged along the fuel gas discharge passage 44b in the direction of arrow A.

[0057] The coolant supplied to the coolant inlet passage 42a is then supplied to the coolant flow field 50 between the first separator 14 and the second separator 16, and then flows in the direction of arrow B. After cooling the MEA 20, the coolant is discharged from the coolant outlet passage 42b.

[0058] The above embodiment may be modified as follows.

[0059] (Variation 1) 4 is a cross-sectional view taken along line II-II in FIG. 1 according to a modified example. In this modified example, the first catalyst layer 24 is bonded to the anode electrode 22 (first electrode 22). For example, the first catalyst layer 24 is bonded to the anode electrode 22 via an ion-conductive polymer binder. In this modified example, the outer peripheral edge 24e of the first catalyst layer 24 is disposed between the frame sheet member 30 and the first electrode 22.

[0060] In this manner, the first catalyst layer 24 may be bonded to the anode electrode 22 (first electrode 22). The second catalyst layer 25 may be bonded to the electrolyte membrane 21 or to the cathode electrode 23 (second electrode 23).

[0061] (Variation 2) Although not shown, the outer peripheral edge 24e of the first catalyst layer 24 may be in contact with the inner peripheral edge 30e of the frame sheet member 30 without being disposed between the electrolyte membrane 21 and the frame sheet member 30 or between the frame sheet member 30 and the first electrode 22. In this case, the first catalyst layer 24 may be bonded to the electrolyte membrane 21 or the first electrode 22.

[0062] The present invention that can be understood from the above description is disclosed below.

[0063] (Appendix 1) The present invention provides a framed membrane-electrode assembly (10) including a membrane-electrode assembly (20) including an electrolyte membrane (21), a first electrode (22), and a second electrode (23), and a resin frame sheet member (30) provided around the entire periphery of the membrane-electrode assembly. The first electrode and the second electrode extend outward from the outer circumferential edge (21e) of the electrolyte membrane toward the frame sheet member along their entire periphery, and an outer circumferential portion (22PT) of the first electrode is joined to one surface (30f1) of the frame sheet member along its entire periphery, and an outer circumferential portion (23PT) of the second electrode is joined to the other surface (30f2) of the frame sheet member along its entire periphery.

[0064] This makes it possible to prevent dust from getting mixed in. As a result, it is possible to prevent a decrease in the efficiency of the electrochemical reaction in the membrane-electrode assembly. It is also possible to prevent deterioration of the electrolyte membrane.

[0065] (Appendix 2) In the framed membrane-electrode structure described in Appendix 1, the frame sheet member may have a first joint (30a) to which the first electrode and the second electrode are respectively joined, and the width (L3) of the first joint in the direction from the outside to the inside of the frame sheet member may be 0.4 mm or more. This makes it possible to substantially prevent dust from getting mixed in.

[0066] (Appendix 3) In the framed membrane-electrode structure described in Supplementary Note 1, the first electrode may have a first inclined portion (22t) around the entire periphery, the second electrode may have a second inclined portion (23t) around the entire periphery, the first inclined portion may approach the second electrode from the outside to the inside, and the second inclined portion may be located outside the first inclined portion and may be farther from the first electrode from the outside to the inside. This allows the thickness of the membrane-electrode structure to be made as thin as possible.

[0067] (Appendix 4) In the framed membrane-electrode structure described in Supplementary Note 3, the width (L2) of the second inclined portion in the direction from the outside to the inside of the frame sheet member may be shorter than the width (L1) of the first inclined portion in the direction from the outside to the inside of the frame sheet member over the entire periphery, thereby making it possible to make the thickness of the membrane-electrode structure as thin as possible.

[0068] (Appendix 5) In the framed membrane-electrode assembly described in Appendix 1, the membrane-electrode assembly may have a first catalyst layer (24) provided between the electrolyte membrane and the first electrode, and a second catalyst layer (25) provided between the electrolyte membrane and the second electrode, and the outer peripheral edge (24e) of the first catalyst layer may be located inside the outer peripheral edge (25e) of the second catalyst layer over the entire circumference. This makes it possible to minimize the amount of catalyst used.

[0069] (Appendix 6) In the framed membrane-electrode assembly described in Appendix 5, the outer peripheral edge of the first catalyst layer may be disposed between the electrolyte membrane and the frame sheet member, or between the frame sheet member and the first electrode. This can prevent the electrolyte membrane from being exposed inside the membrane-electrode assembly. As a result, a decrease in the efficiency of the electrochemical reaction can be prevented.

[0070] (Appendix 7) In the framed membrane-electrode structure described in Appendix 1, each of the first electrode and the second electrode may be joined to the frame sheet member by adhesion or welding over the entire periphery, thereby making it possible to prevent dust from entering the interior of the membrane-electrode structure.

[0071] (Appendix 8) In the framed membrane-electrode assembly described in Appendix 1, the outer peripheral edge of the electrolyte membrane may be sandwiched between the second electrode and the frame sheet member along the entire periphery. This makes it possible to prevent the electrolyte membrane from being exposed inside the membrane-electrode assembly. As a result, it is possible to prevent a decrease in the efficiency of the electrochemical reaction.

[0072] The present invention is not limited to the above-described embodiments and modifications, and various modifications are possible within the scope of the gist of the present invention. [Explanation of symbols]

[0073] 10...framed membrane-electrode structure 20...membrane-electrode structure 21... Electrolyte membrane 22... First electrode (anode electrode) 23... Second electrode (cathode electrode) 24... First catalyst layer 25... second catalyst layer 30... frame sheet member 30a...First joint part 30b...Second joint part

Claims

1. a membrane electrode assembly including an electrolyte membrane, a first electrode, and a second electrode; a resin frame sheet member provided around the entire outer periphery of the membrane electrode assembly; A framed membrane electrode structure comprising: the first electrode and the second electrode extend outward from an outer peripheral edge of the electrolyte membrane toward the frame sheet member along the entire periphery, an outer periphery of the first electrode is joined to one surface of the frame sheet member along the entire periphery; an outer periphery of the second electrode is joined to the other surface of the frame sheet member along the entire periphery; a framed membrane-electrode structure in which the outer peripheral edge of the electrolyte membrane is sandwiched between the second electrode and the frame sheet member along the entire periphery;

2. 2. The framed membrane electrode assembly according to claim 1, the frame sheet member has first bonding portions to which the first electrode and the second electrode are bonded, A framed membrane electrode structure, wherein the width of the first joint portion in the direction from the outside to the inside of the frame sheet member is 0.4 mm or more.

3. 2. The framed membrane electrode assembly according to claim 1, the first electrode has a first inclined portion over the entire periphery, the second electrode has a second inclined portion over the entire periphery, the first inclined portion is closer to the second electrode as it goes from the outside to the inside, The second inclined portion is located outside the first inclined portion and becomes increasingly farther from the first electrode as it goes from the outside to the inside.

4. 4. The framed membrane-electrode structure according to claim 3, A framed membrane-electrode structure, wherein the width of the second inclined portion in the direction from the outside to the inside of the frame sheet member is shorter than the width of the first inclined portion in the direction from the outside to the inside of the frame sheet member over the entire circumference.

5. 2. The framed membrane electrode assembly according to claim 1, the membrane electrode assembly includes a first catalyst layer provided between the electrolyte membrane and the first electrode, and a second catalyst layer provided between the electrolyte membrane and the second electrode, A framed membrane electrode structure, wherein the outer peripheral edge of the first catalyst layer is positioned inside the outer peripheral edge of the second catalyst layer over the entire periphery.

6. 6. The framed membrane electrode assembly according to claim 5, A framed membrane electrode assembly, wherein the outer peripheral edge of the first catalyst layer is disposed between the electrolyte membrane and the frame sheet member, or between the frame sheet member and the first electrode.

7. 2. The framed membrane electrode assembly according to claim 1, A framed membrane-electrode structure, wherein each of the first electrode and the second electrode is joined to the frame sheet member by adhesive or welding over the entire periphery.

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