Inspection method of fuel battery

Abstract

To provide an inspecting method of a fuel battery, which can indirectly evaluate a dimension of a product part which is sandwiched between front and back diffusion layers and is not visible after bonding of the diffusion layers.SOLUTION: An inspection method includes: a step of marking inspection marks 60 on a resin frame member 14 and storing an initial position of the inspection marks; a resin frame member joining step of joining the resin frame member to a membrane electrode assembly; a diffusion layer joining step of joining diffusion layers after the resin frame member joining step; and a quality determination step of determining a deformation amount of the resin frame member by comparing the initial position of the inspection marks 60 marked on the resin frame member with the post-bonding position of inspection marks 60a after the membrane electrode assembly, the resin frame member, and the diffusion layers are integrally bonded.SELECTED DRAWING: Figure 3C

Description

[Technical Field]

[0001] The present invention relates to a method for inspecting a fuel cell. [Background technology]

[0002] For example, Patent Document 1 discloses a method for manufacturing a membrane electrode assembly and a fuel cell. According to Patent Document 1, defects in an assembly formed by joining an electrolyte membrane on a first substrate and an electrode on a second substrate are detected.

[0003] Furthermore, Patent Document 1 discloses a manufacturing method in which detected defective products are given marks indicating the defect at different positions so that the marks can be detected in a bonded state, and a diffusion layer is bonded to a bonded body without any marks. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6024629 Summary of the Invention [Problem to be solved by the invention]

[0005] However, if the electrolyte membrane thermally shrinks during the bonding of the diffusion layers by thermocompression, the resin frame member bonded to the membrane electrode assembly is likely to shift position due to the thermal shrinkage of the electrolyte membrane, resulting in wrinkles and deformation. If wrinkles or deformation occur in the resin frame member, gas leakage or a reduction in the power generation area due to poor sealing may occur, which may affect the power generation performance of the fuel cell.

[0006] Furthermore, after the diffusion layer is thermocompression bonded, the bonding state (boundary) between the electrolyte membrane and the resin frame member cannot be visually observed, and even if deformation occurs due to thermal contraction, the only way to inspect (evaluate the boundary) is by examining the shade of an image using an X-ray or the like, resulting in problems of low inspection accuracy and efficiency.

[0007] The present invention has been made in consideration of the above points, and aims to provide a fuel cell inspection method that makes it possible to indirectly evaluate the dimensions of the product part that is sandwiched between the front and back diffusion layers and cannot be seen after the diffusion layers are bonded. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the present invention provides an inspection method for a fuel cell including a membrane electrode assembly comprising an electrolyte membrane and a pair of electrode catalyst layers provided on both sides of the electrolyte membrane, a resin frame member joined to the outer periphery of the membrane electrode assembly to hold the membrane electrode assembly, and a diffusion layer covering both sides of the membrane electrode assembly, at least an outer edge of which overlaps with the resin frame member, the method comprising the steps of: marking an inspection mark on the resin frame member and storing an initial position of the inspection mark; a resin frame member joining step of joining the resin frame member to the membrane electrode assembly; a diffusion layer joining step of joining the diffusion layer after the resin frame member joining step; and a pass / fail determination step of determining an amount of deformation of the resin frame member by comparing the initial position of the inspection mark marked on the resin frame member with a post-joining position of the inspection mark after the membrane electrode assembly, the resin frame member, and the diffusion layer are integrally joined. [Effects of the Invention]

[0009] The present invention provides a fuel cell inspection method that can indirectly evaluate the dimensions of the product part that is sandwiched between the front and back diffusion layers and cannot be seen after the diffusion layers are bonded. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is an exploded perspective view of a membrane electrode assembly and a resin frame member. [Figure 2] FIG. 2 is a longitudinal cross-sectional view of a resin frame-equipped membrane electrode assembly taken along the horizontal direction. [Figure 3A] FIG. [Figure 3B]FIG. 10 is a plan view showing the initial positions of a plurality of inspection marks marked on the resin frame member. [Figure 3C] 10 is a plan view showing the position of the inspection mark after the membrane electrode assembly, the resin frame member, and the diffusion layer are integrally bonded together. FIG. [Figure 4] 10 is an explanatory view showing a state in which the resin frame member is deformed due to thermal contraction of the electrolyte membrane when the diffusion layer is bonded. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] Next, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0012] First, the structure of a power-generating cell that passed the fuel cell inspection method according to an embodiment of the present invention will be described. This power-generating cell (fuel cell) is configured with a resin-framed membrane electrode assembly 10 (see FIG. 2) and a pair of separators (not shown) arranged on both sides of the resin-framed membrane electrode assembly 10. The power-generating cell is a horizontally elongated rectangular polymer electrolyte fuel cell. A plurality of power-generating cells are stacked, for example, horizontally or vertically, to form a fuel cell stack. The fuel cell stack is installed, for example, in a fuel cell electric vehicle as an on-board fuel cell stack.

[0013] The resin-framed membrane electrode assembly 10 includes a membrane electrode assembly 12 and a resin frame member 14 joined to the outer periphery of the membrane electrode assembly 12 and extending around the outer periphery (see FIG. 1). Note that the diffusion layer joined to the membrane electrode assembly 12 is not shown in FIG.

[0014] As shown in FIG. 2, the membrane electrode assembly 12 includes an electrolyte membrane 16 having a rectangular shape in a plan view, an anode electrode (electrode catalyst layer) 18 provided on either the front or back surface of the electrolyte membrane 16, and a cathode electrode (electrode catalyst layer) 20 provided on the other of the front or back surface of the electrolyte membrane 16 (see FIG. 1).

[0015] The electrolyte membrane 16 is made of, 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 front and back surfaces of the electrolyte membrane 16 are sandwiched between an anode electrode 18 and a cathode electrode 20.

[0016] In this embodiment, the cathode electrode 20 has larger planar dimensions (external dimensions) than the anode electrode 18, and the cathode electrode 20 and the electrolyte membrane 16 have the same or approximately the same planar dimensions (external dimensions). In other words, as shown in Fig. 2, the outer peripheral edge 22 of the cathode electrode 20 and the outer peripheral edge 24 of the electrolyte membrane 16 are located at the same position in the thickness direction, and the outer peripheral edge 26 of the anode electrode 18 is located more inward in the thickness direction than the outer peripheral edge 22 of the cathode electrode 20 and the outer peripheral edge 24 of the electrolyte membrane 16.

[0017] The membrane electrode assembly 12 has a pair of diffusion layers covering both surfaces of the membrane electrode assembly 12, with at least the outer edge overlapping the resin frame member 14 in the thickness direction. The pair of diffusion layers comprises an anode electrode-side gas diffusion layer 28 laminated on one surface of the anode electrode 18 and a cathode electrode-side gas diffusion layer 30 laminated on one surface of the cathode electrode 20. An outer peripheral edge 32 of the anode electrode-side gas diffusion layer 28 and an outer peripheral edge 34 of the cathode electrode-side gas diffusion layer 30 are located at the same positions in the thickness direction as the outer peripheral edge 22 of the cathode electrode 20 and the outer peripheral edge 24 of the electrolyte membrane 16, respectively. The anode electrode-side gas diffusion layer 28 and the cathode electrode-side gas diffusion layer 30 are each formed from carbon paper, carbon cloth, or the like.

[0018] The resin frame member 14 is composed of two frame-shaped sheets having approximately the same thickness but different planar dimensions (external dimensions). The resin frame member 14 has an opening (window frame) 35 (see FIG. 3A) that is approximately rectangular in plan view formed at its inner peripheral edge.

[0019] Specifically, the resin frame member 14 has a first frame-shaped sheet body 40, the inner periphery 38 of which is bonded to one surface of the membrane electrode assembly 12 via an adhesive layer 36 described below, and a second frame-shaped sheet body 42 bonded to the first frame-shaped sheet body 40 via the adhesive layer 36. The first frame-shaped sheet body 40 and the second frame-shaped sheet body 42 are bonded to each other in the thickness direction by the adhesive layer 36 made of an adhesive. An inner periphery 44 of the second frame-shaped sheet body 42 is bonded to the other surface of the membrane electrode assembly 12 via the adhesive layer 36.

[0020] The inner peripheral edge 46 of the first frame-shaped sheet 40, which is joined to one surface of the membrane electrode assembly 12, protrudes inward more than the inner peripheral edge 48 of the second frame-shaped sheet 42, which is joined to the other surface of the membrane electrode assembly 12. It is necessary to ensure a dimensional guarantee for the dimension from the outer peripheral edge 32 of the anode electrode side gas diffusion layer 28 to the inner peripheral edge 46 of the first frame-shaped sheet 40, which is joined to one surface of the membrane electrode assembly 12. It is also necessary to ensure a dimensional guarantee for the dimension from the outer peripheral edge 34 of the cathode electrode side gas diffusion layer 30 to the inner peripheral edge 48 of the second frame-shaped sheet 42, which is joined to the other surface of the membrane electrode assembly 12.

[0021] The resin-framed membrane electrode assembly 10 further includes an overlap area 50, a tent area 52, and an active area 54. The overlap area 50 is formed by an overlapping region of the membrane electrode assembly 12, the outer periphery of the diffusion layers (28, 30), and the inner periphery of the resin frame member 14. The tent area 52 is formed by an approximately triangular space 56 formed between the inner periphery 46 of the first frame-shaped sheet body 40, the electrolyte membrane 16, and the anode electrode-side gas diffusion layer 28. The active area 54 is formed by an overlapping region of the membrane electrode assembly 12 and the diffusion layer.

[0022] The structure of the power generating cell that passed the fuel cell inspection method according to this embodiment is basically configured as described above, and its effects will now be described.

[0023] First, the manufacturing process of the resin frame-equipped membrane electrode assembly 10 will be described in detail below. A process is carried out in which a plurality of inspection marks 60 (see FIG. 3B) are marked on the resin frame member 14 and the initial positions of the inspection marks 60 are stored. In this process of storing the initial positions of the inspection marks 60, for example, the marked resin frame member 14 is imaged by an imaging means (not shown), and the image is stored as an initial image. In this initial image, the initial positions of the inspection marks 60 can be recognized. Furthermore, the inspection marks 60 can be marked by a printing process using, for example, a printer (not shown).

[0024] It is preferable that at least one inspection mark 60 is marked on each corner and each side that constitutes the opening 35 of the resin frame member 14. Specifically, in this embodiment, a total of eight inspection marks 60 are placed at each of the four corners of the opening 35, which has a substantially rectangular shape in plan view, and at intermediate positions between the four corners of each side that constitutes the opening 35, but the number of inspection marks 60 is not limited to this.

[0025] Furthermore, the multiple inspection marks 60 are positioned at positions that will not be covered by the diffusion layer that will be bonded in a subsequent diffusion layer bonding process. This is because if the inspection marks 60 were marked at positions where the diffusion layer will be bonded to the resin frame member 14 in the subsequent diffusion layer bonding process, the inspection marks 60 would be covered by the diffusion layer and hidden. For this reason, the multiple inspection marks 60 are preferably provided at positions spaced a predetermined distance from the inner circumferential edge of the opening 35 toward the outer circumferential side (positions that do not overlap with the diffusion layer in the thickness direction). In other words, the multiple inspection marks 60 should be provided in a visible region of the resin frame member 14 excluding the overlap area 50 (see FIG. 2).

[0026] Furthermore, the inspection mark 60 may be provided on either or both of the first frame-shaped sheet body 40 and the second frame-shaped sheet body 42. When the inspection mark 60 is provided on both, it is necessary to prevent misalignment between one inspection mark 60 and the other inspection mark 60.

[0027] Next, a resin frame member joining step is performed to join the resin frame member 14 to the membrane electrode assembly 12. An adhesive is applied to the outer periphery of the membrane electrode assembly 12 to join the membrane electrode assembly 12 to the first frame-shaped sheet body 40 and the second frame-shaped sheet body 42.

[0028] Next, after the resin frame member joining step, a diffusion layer joining step is performed to join the diffusion layers. The anode electrode side gas diffusion layer 28 is laminated on one surface of the anode electrode 18 and on a portion of the inner periphery of the first frame-shaped sheet body 40. At approximately the same time, the cathode electrode side gas diffusion layer 30 is laminated on one surface of the cathode electrode 20 and on a portion of the inner periphery of the second frame-shaped sheet body 42. After laminating the diffusion layers, the diffusion layers in the active area 58 and the membrane electrode assembly 12 are heated and pressed together using a thermocompression bonding device (not shown). The thermocompression bonding device includes a room-temperature mold (lower mold), a heated mold (upper mold), and a cushioning material (not shown) that is positioned between the room-temperature mold and the heated mold and on which the material to be pressed is placed.

[0029] Furthermore, before the pass / fail determination process, a post-bonding storage process is performed in which an image of the resin frame member 14 after the diffusion layer has been bonded is taken and the captured image is stored as a post-bonding image. In the pass / fail determination process following the post-bonding storage process, the initial position of the inspection mark 60 in the initial image is compared with the post-bonding position of the inspection mark 60a in the post-bonding image, for example, by image recognition means (not shown), and the amount of deformation of the resin frame member 14 is measured (see FIG. 3C). In this pass / fail determination process, if the amount of deformation of the resin frame member 14 exceeds a predetermined value, it is determined to be a defective product.

[0030] In the pass / fail judgment process, the amount of deformation of the resin frame member 14 is judged based on the amount of positional deviation measured between the initial position of the inspection mark 60 and the position of the inspection mark 60 after bonding. If the amount of positional deviation between the initial position of the inspection mark 60 and the position of the inspection mark 60 after bonding exceeds a predetermined value, the product is judged to be defective.

[0031] 4, when the diffusion layers are bonded by thermocompression bonding, thermal shrinkage (shrinkage due to heat) of the electrolyte membrane 16 occurs (see arrow A). At the same time or approximately at the same time, the resin frame member 14 bonded to the membrane electrode assembly 12 may shift in position due to the thermal shrinkage of the electrolyte membrane 16, resulting in wrinkles or deformation (see arrow B). If wrinkles or deformation occur in the resin frame member 14, this may result in gas leakage due to poor sealing or a reduction in the power generation area, which may affect the power generation performance of the fuel cell.

[0032] In this embodiment, in the quality determination process, the displacement or deformation of the resin frame member 14 that occurs due to thermal shrinkage of the electrolyte membrane 16 is estimated (predicted) by measuring the displacement between the initial position of the inspection mark 60 and the position of the inspection mark 60a after bonding (see FIG. 3C ). This ensures reliable dimensional assurance from the outer peripheral edge 32 of the anode electrode side gas diffusion layer 28 to the inner peripheral edge 46 of the first frame-shaped sheet body 40, and from the outer peripheral edge 34 of the cathode electrode side gas diffusion layer 30 to the inner peripheral edge 48 of the second frame-shaped sheet body 42. As a result, this embodiment provides a fuel cell inspection method that can indirectly evaluate the dimensions of product parts that are sandwiched between the front and back diffusion layers after bonding of the diffusion layers and cannot be seen.

[0033] Furthermore, in this embodiment, the introduction of an X-ray transmission device is not required, and the dimensional measurement and dimensional assurance of the opening 35 in the resin frame member 14 can be performed, and the inspection accuracy and inspection efficiency can be improved compared to inspection based on the shade of the image.

[0034] In FIG. 4, the amount of thermal contraction of the electrolyte membrane 16 indicated by the white arrow A and the amount of deformation of the resin frame member 14 indicated by the white arrow B are the same or approximately the same.

[0035] Furthermore, in this embodiment, it is preferable that at least one inspection mark 60 be marked on each corner and each side that constitutes the opening (window frame) 35 of the resin frame member 14. In this embodiment, a total of eight inspection marks 60 are placed at each of the four corners of the opening 35, which is approximately rectangular in plan view, and at the middle positions of the four corners of each side that constitutes the opening 35. This makes it possible to measure the amount of deformation of the vertical frame on one side and the vertical frame on the other side of the resin frame member 14, and the amount of deformation of the horizontal frame on one side and the horizontal frame on the other side of the resin frame member 14, and thus the amount of deformation of the resin frame member 14 can be reliably and stably estimated.

[0036] In this embodiment, in the quality determination process, if the deformation amount of the resin frame member 14 exceeds a predetermined value, it is determined to be a defective product. As a result, in this embodiment, dimensional control of the opening (window frame) 35 of the resin frame member 14 can be performed reliably and stably. [Explanation of symbols]

[0037] 10 Resin-framed electrolyte membrane-electrode assembly 12 Membrane electrode assembly 14 Resin frame member 16 Electrolyte membrane 18 Anode electrode (electrode catalyst layer) 20 Cathode electrode (electrode catalyst layer) 28 Anode electrode side diffusion layer (diffusion layer) 30 Cathode electrode side diffusion layer (diffusion layer) 60 Inspection mark (initial position) 60a Inspection mark (post-bonding position)

Claims

1. a membrane electrode assembly comprising an electrolyte membrane and a pair of electrode catalyst layers provided on both sides of the electrolyte membrane; a resin frame member joined to the outer periphery of the membrane electrode assembly to hold the membrane electrode assembly; a diffusion layer covering both surfaces of the membrane electrode assembly and having at least an outer edge portion overlapping the resin frame member, the method comprising: a step of marking an inspection mark on the resin frame member and storing an initial position of the inspection mark; a resin frame member joining step of joining the resin frame member to the membrane electrode assembly; a diffusion layer bonding step of bonding the diffusion layer after the resin frame member bonding step; a quality determination step of determining the amount of deformation of the resin frame member by comparing an initial position of the inspection mark marked on the resin frame member with a post-bonding position of the inspection mark after the membrane electrode assembly, the resin frame member, and the diffusion layer are integrally bonded; 1. A fuel cell inspection method comprising:

2. 2. The fuel cell inspection method according to claim 1, The fuel cell inspection method is characterized in that the inspection marks are marked at least one on each corner and each side of the resin frame member that constitutes the opening.

3. 2. The fuel cell inspection method according to claim 1, The fuel cell inspection method is characterized in that, in the quality determining step, it is determined that the resin frame member is defective if the deformation amount of the resin frame member exceeds a predetermined value.

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