Laser cutting method for membrane electrode gas diffusion layer assembly

Abstract

When a sheet piece 3 used for constituting each cell is cut out from a continuous AnMEGA sheet 1 by a laser cutting method, the width of a part of a gas diffusion layer 10 projecting outward in the surface direction from an electrolyte membrane 12 and a catalyst layer 11 on an edge surface is made as narrow as possible.SOLUTION: The method for cutting out the sheet piece by cutting the sheet of the anode-side membrane electrode gas diffusion layer assembly with the laser beam Lz includes a first cutting step of cutting the sheet by irradiating the sheet with the laser beam along a first cutting line extending in a surface direction of the sheet, and a second cutting step of cutting the gas diffusion layer by irradiating the gas diffusion layer with the laser beam along a second cutting line extending in the surface direction of the gas diffusion layer exposed inward in the surface direction from the first cutting line of the sheet piece cut in the first cutting step.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a membrane electrode-gas diffusion layer assembly, and more particularly to a method for cutting a membrane electrode-gas diffusion layer assembly using a laser to cut sheet pieces having dimensions to be used for cells from a continuous sheet of the membrane electrode-gas diffusion layer assembly. [Background technology]

[0002] An anode membrane electrode gas diffusion layer assembly (AnMEGA) used in a fuel cell is generally formed by cutting a sheet in which a continuous anode catalyst layer, an electrolyte membrane, and a cathode catalyst layer are laminated on a continuous sheet of gas diffusion layer into sheet pieces of dimensions that constitute each cell. A laser cutting method is typically used to cut the AnMEGA sheet pieces (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2010-118237 Summary of the Invention [Problem to be solved by the invention]

[0004] When cutting sheet pieces for each cell from a continuous sheet of AnMEGA using a laser as described above, if the sheet pieces are cut with only one laser irradiation, the cut edge surface may be somewhat irregular. On the other hand, if the sheet pieces are cut with two separate laser irradiations, the cut edge surface will be smooth and uniform. Therefore, it is preferable to cut the sheet with two separate laser irradiations to form as smooth an edge surface as possible.

[0005] When a laser is applied to an AnMEGA for cutting, the heat of the laser causes shrinkage of each layer at its edge, to varying degrees. More specifically, the electrolyte membrane and catalyst layer shrink more than the gas diffusion layer during laser cutting. As a result, the gas diffusion layer protrudes outward in the planar direction beyond the electrolyte membrane and catalyst layer at the edge of the laser-cut sheet piece. The protruding edge of the gas diffusion layer does not contribute to power generation and is therefore wasted. Such a protruding gas diffusion layer configuration increases the cell's external dimensions, reducing the ratio of the power generation area to the cell's external dimensions and resulting in inefficiency. That is, when cutting to cut out sheet pieces, it is preferable to narrow the protruding edge of the gas diffusion layer as much as possible.

[0006] In view of the above circumstances, the main objective of the present invention is to narrow as much as possible the width of the portion of the gas diffusion layer that protrudes outward in the planar direction beyond the electrolyte membrane and catalyst layer at the edge surface when cutting out sheet pieces used to construct each cell from a continuous AnMEGA sheet using a laser cutting method. [Means for solving the problem]

[0007] According to the present invention, the above-mentioned problem is solved by a method for cutting a sheet of an anode-side membrane electrode-gas diffusion layer assembly using a laser to cut out a sheet piece, the method comprising the steps of: a first cutting step of irradiating a laser beam along a first cutting line extending in a surface direction of the sheet to cut the sheet; a second cutting step of irradiating a laser beam along a second cutting line extending in a surface direction of the gas diffusion layer exposed inward in the surface direction from the first cutting line cut in the sheet piece in the first cutting step, thereby cutting the gas diffusion layer; This is achieved by a method comprising:

[0008] In the above configuration, the "anode-side membrane electrode-gas diffusion layer assembly sheet" refers to an assembly sheet in which an anode catalyst layer, an electrolyte membrane, and a cathode catalyst layer are laminated in this order on an anode-side gas diffusion layer, which is a component of a fuel cell. Typically, the sheet may be held and stored in a rolled state, and the AnMEGA sheet pieces used for each cell are cut from the sheet during its formation. The laser used to cut the sheet may be a laser capable of cutting sheets used in this field.

[0009] In the above configuration, in the first cutting process, a laser is irradiated onto the AnMEGA sheet along a first cutting line extending in the plane direction of the sheet. This burns and cuts the anode catalyst layer and electrolyte membrane in the laser irradiation area (usually, the cathode catalyst layer is only laminated up to the inward side of the electrolyte membrane in the plane direction). Furthermore, at least a portion of the gas diffusion layer is also lost and cut. Furthermore, the anode catalyst layer and electrolyte membrane shrink more than the gas diffusion layer due to the heat of the laser, leaving the gas diffusion layer exposed in the plane direction inside the first cutting line. Therefore, in the second cutting process, as described above, a laser is irradiated along a second cutting line extending in the plane direction of the gas diffusion layer exposed at the edge of the sheet, cutting the gas diffusion layer. According to this configuration, the second laser irradiation cuts off the gas diffusion layer exposed at the edge of the sheet piece in the first cutting process, making it possible to further narrow the width of the portion of the gas diffusion layer that protrudes outward in the planar direction beyond the electrolyte membrane and catalyst layer. [Effects of the Invention]

[0010] Thus, according to the method of the present invention, when cutting out sheet pieces to be used to construct each cell from a continuous AnMEGA sheet using a laser cutting method, it is possible to narrow the width of the gas diffusion layer portion on the edge surface, thereby making it possible to reduce the external dimensions of the cell and increase the ratio of the area of ​​the region capable of generating electricity to the external dimensions of the cell.

[0011] Other objects and advantages of the present invention will become apparent from the following description of preferred embodiments of the invention. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram of a laser cutting system for cutting sheet pieces from an AnMEGA sheet to which the method of this embodiment is applied. [Figure 2] 2(A) to 2(E) are schematic cross-sectional views of an AnMEGA sheet or sheet piece showing the process of cutting the AnMEGA sheet with a laser. (A) is the state before cutting, (B) is the state during the first cutting with the laser, (C) is the state after the first cutting, (D) is the state before the second cutting, and (E) is the state after the second cutting. [Figure 3] Figure 3(A) is a schematic cross-sectional view of an AnMEGA sheet piece to be formed, and Figure 3(B) is a schematic cross-sectional view of an AnMEGA sheet piece to which an adhesive layer and adhesive sheet for laminating to a cathode gas diffusion layer (CaGDL) have been applied. [Explanation of symbols]

[0013] 1...AnMEGA sheet, 2...cutting line, 3...AnMEGA sheet piece, 4...laser oscillator, 5...galvanometer scanner, 6...galvanometer controller, 7...control device (computer device), 10...gas diffusion layer, 11...anode catalyst layer, 12...electrolyte membrane, 13...cathode catalyst layer, 14...adhesive layer, 15...adhesive sheet BEST MODE FOR CARRYING OUT THE INVENTION

[0014] The present invention will now be described in detail with reference to some preferred embodiments thereof with reference to the accompanying drawings, in which like reference numerals indicate like parts.

[0015] AnMEGA configuration 3(A), AnMEGA used in fuel cells has a configuration in which an anode catalyst layer 11, an electrolyte membrane 12, and a cathode catalyst layer 13 are laminated in this order on a sheet-like gas diffusion layer 10. After AnMEGA is cut into sheet pieces for each cell, as shown in FIG. 3(B), an adhesive layer 14 is applied to the edge where the electrolyte membrane 12 is exposed, and an adhesive sheet 15 that connects to the cell separator is attached to the upper edge side. A cathode gas diffusion layer (CaGDL) (not shown) is arranged on the inner side in the surface direction, facing the cathode catalyst layer 13.

[0016] Laser cutting system for cutting out AnMEGA sheet pieces After the AnMEGA is formed into a continuous sheet, it is cut into sheet pieces for use in cells using a laser cutting system such as that shown in FIG. 1. The laser cutting system may typically include, as shown in the figure, an oscillator 4 that emits laser light, a galvanometer scanner 5 that moves the irradiation position of the laser light beam Lz, a galvanometer controller 6 that issues control commands to the galvanometer scanner 5, and a control device 7 that controls the galvanometer controller 6 to instruct the laser light beam Lz to scan along a desired shape. The control device 7 may be a computer device that operates according to a program. In the cutting process, a long sheet 1 of AnMEGA is unfolded and pulled out on a cutting table (not shown), and the laser light beam Lz is introduced from the oscillator 4 to the galvanometer scanner 5, and is irradiated while being scanned along a cutting line 2 corresponding to the outline of the sheet piece 3 for use in the cell, thereby cutting out the sheet piece 3.

[0017] Regarding the irradiation of this laser light beam, as described in the Summary of the Invention, if the sheet piece 3 is completely cut out by only one laser irradiation, the edge surface will be somewhat irregular, so it is preferable to adjust the intensity of the laser light beam so that the sheet piece 3 is cut out by two laser irradiations. In this case, the laser light beam is scanned so as to go around the cutting line 2 twice.

[0018] Improved cutting position As described above, in the cutting process in which a laser beam is locally irradiated onto a sheet in which the anode catalyst layer 11, the electrolyte membrane 12, and the cathode catalyst layer 13 are laminated on the gas diffusion layer 10, the laser beam Lz is aimed at the cutting line T1 on the surface where the electrolyte membrane 12 is exposed, as shown in Fig. 2(A) (because the cathode catalyst layer 13 is laminated only up to an inner side in the planar direction of the electrolyte membrane 12, the laser beam Lz is irradiated onto the exposed surface of the electrolyte membrane 12.) As a result, the films and layers in the beam-irradiated region are burned and cut, as shown in Fig. 2(B). At this time, the anode catalyst layer 11 and the electrolyte membrane 12 are retracted inward in the planar direction by the heat of the laser, as indicated by the arrow rd. Therefore, after the first irradiation of the laser light beam, the gas diffusion layer 10 protrudes outward in the planar direction beyond the anode catalyst layer 11 and the electrolyte membrane 12, as indicated by the symbol w, as shown in FIG. 2(C), and its surface is exposed.

[0019] As described above, the exposed portion of the gas diffusion layer 10 does not contribute to power generation and increases the external dimensions of the cell, resulting in a wasted portion that reduces the area of ​​the power generation region relative to the external dimensions of the cell. Therefore, in this embodiment, as shown in FIG. 2(D), the second irradiation of the laser light beam Lz is aimed at a cutting line T2 on the surface where the gas diffusion layer 10 is exposed, which is inward in the planar direction from the cutting line T1, and the laser light beam Lz is irradiated along the cutting line T2. The cutting line T2 is set to extend along the entire periphery of the sheet piece 3, inward in the planar direction from the cutting line T1. With this configuration, as shown in FIG. 2(E), at least a portion of the edge portion of the gas diffusion layer 10 exposed by the first irradiation of the laser light beam is cut off, thereby narrowing the width of the wasted portion that contributed to power generation and enabling the cell dimensions to be further reduced.

[0020] The above description has been made in relation to the embodiments of the present invention, but it will be apparent that many modifications and changes will be readily apparent to those skilled in the art, and the present invention is not limited to the above-described exemplary embodiments, but can be applied to various devices without departing from the concept of the present invention.

Claims

[Claim 1] A method for cutting a sheet of an anode-side membrane electrode-gas diffusion layer assembly using a laser to cut out a sheet piece, comprising: a first cutting step of irradiating a laser beam along a first cutting line extending in a surface direction of the sheet to cut the sheet; a second cutting step of irradiating a laser beam along a second cutting line extending in a surface direction of the gas diffusion layer exposed inward in the surface direction from the first cutting line cut in the sheet piece in the first cutting step, thereby cutting the gas diffusion layer; A method comprising:

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