JP2017107645A - Fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the tear of an electrolyte membrane of a membrane-electrode assembly.SOLUTION: A fuel cell comprises: a membrane-electrode assembly; two gas diffusion layers disposed on opposing faces of the membrane-electrode assembly respectively, of which one gas diffusion layer is smaller than the membrane-electrode assembly and has an outer periphery located inside the outer periphery of the membrane-electrode assembly in plan view; a resin frame member with a gap provided between the outer periphery of the one gas diffusion layer and the resin frame member; a protection film arranged on one face of opposing faces of the one gas diffusion layer, which is located on the side opposite the membrane-electrode assembly so that it extends over the resin frame member and the one gas diffusion layer; and an adhesive filling gaps formed among the resin frame member, the gas diffusion layers, the membrane-electrode assembly, and the protection film.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a fuel cell.

  Patent Document 1 discloses a membrane electrode assembly having a catalyst layer formed on both surfaces of an electrolyte membrane, a gas diffusion layer having a small planar dimension disposed on one surface of the membrane electrode assembly, and a gas having a small planar dimension. There is described a fuel cell including a resin frame disposed on the outer periphery of a diffusion layer with a gap, and a filler is filled in the gap.

JP2015-125925A

  Although the filler of Patent Document 1 fills in the gap, it does not reach the surface of the gas diffusion layer or the resin frame, so that the surface pressure cannot be applied to the membrane electrode assembly through the filler. Therefore, the deformation that the membrane electrode assembly enters the gap cannot be suppressed, and the electrolyte membrane of the membrane electrode assembly may be torn.

  The present invention has been made to solve the above-described problems, and can be realized as the following forms.

(1) According to one aspect of the present invention, a fuel cell is provided. The fuel cell includes a membrane electrode assembly and two gas diffusion layers disposed on both surfaces of the membrane electrode assembly, and one gas diffusion layer of the two gas diffusion layers is the membrane electrode. A gap is formed between two gas diffusion layers that are smaller than the joined body and in which the outer periphery of the one gas diffusion layer is inside the outer periphery of the membrane electrode assembly and the outer periphery of the one gas diffusion layer in plan view. The resin frame member arranged in an open manner and the surface opposite to the membrane electrode assembly of both surfaces of the one gas diffusion layer are disposed so as to straddle the resin frame member and the one gas diffusion layer. A protective film; and an adhesive that fills a gap formed between the resin frame member, the gas diffusion layer, the membrane electrode assembly, and the protective film.
According to this embodiment, since the adhesive fills the gap formed between the resin frame member, the gas diffusion layer, the membrane electrode assembly, and the protective film, the membrane electrode assembly (electrolyte membrane) is interposed via the adhesive. ) Can be applied with surface pressure. As a result, deformation of the electrolyte membrane can be suppressed, and membrane tearing can be suppressed.

  The present invention can be realized in various forms, for example, in the form of a fuel cell, a fuel cell stack, a method for manufacturing a fuel cell, a method for manufacturing a fuel cell stack, and the like. .

Sectional drawing which shows schematic structure of a fuel cell stack. The top view which looked at the joined body of MEA and the resin frame member from the cathode side. The figure which abbreviate | omitted illustration of the filling member from FIG. Explanatory drawing which expands and shows the area | region X of FIG. The top view which looked at the filling member from the adhesive agent side. Sectional drawing of a filling member. Explanatory drawing which shows the manufacturing process of an electric power generation unit. Explanatory drawing which shows the electric power generation unit of a comparative example. Explanatory drawing which shows the electric power generation unit of 2nd Embodiment, and its manufacturing process.

First embodiment:
FIG. 1 is a cross-sectional view showing a schematic configuration of the fuel cell stack 10. The fuel cell stack 10 has a configuration in which a plurality of power generation units 100 are arranged in series. Each of the power generation units 100 is a fuel cell (single cell). Each power generation unit 100 includes a membrane electrode assembly 110, a cathode side gas diffusion layer 120, an anode side gas diffusion layer 130, a resin frame member 140, separator plates 150 and 160, and a filling member 195. .

  The membrane electrode assembly 110 (Membrane and Electrode Assembly 110, hereinafter referred to as “MEA110”) has a configuration having catalyst layers on two surfaces of the electrolyte membrane. The detailed configuration of the MEA 110 will be described later. The cathode side gas diffusion layer 120 is disposed so as to contact the catalyst layer on the cathode side of the MEA 110, and the anode side gas diffusion layer 130 is disposed so as to contact the catalyst layer on the anode side of the MEA 110. The resin frame member 140 is a member that supports the outer edge of the MEA 110, and is disposed so as to surround the entire outer periphery of the MEA 110, the cathode-side gas diffusion layer 120, and the anode-side gas diffusion layer 130. Separator plates 150 and 160 are arranged so as to sandwich MEA 110, cathode side gas diffusion layer 120, anode side gas diffusion layer 130, and resin frame member 140. The resin frame member 140 described above also functions as a seal member that seals between the separator plates 150 and 160. The filling member 195 includes a protective film 190 and an adhesive 180. The protective film 190 is disposed on the opposite side of the cathode side gas diffusion layer 120 from the MEA 110 so as to straddle the resin frame member 140 and the cathode side gas diffusion layer 120. The adhesive 180 is filled in a gap between the resin frame member 140 and the cathode side gas diffusion layer 120, fixes the resin frame member 140 and the protective film 190, and the cathode side gas diffusion layer 120 and the protective film 190. And are fixed.

  Separator plates 150 and 160 are metal plate-like members having irregularities. A cathode gas flow path 155 is formed between the separator plate 150 and the cathode side gas diffusion layer 120, and an anode gas flow path 165 is formed between the separator plate 160 and the anode side gas diffusion layer 130. In addition, a coolant channel 175 is formed between the separator plate 150 and the separator plate 160. In the present embodiment, the separator plates 150 and 160 are formed and arranged so that the top 150t of the convex portion of the separator plate 150 and the top 160t of the convex portion of the separator plate 160 are in contact with each other. Here, the convex portion of the separator plate 150 means a portion of the separator plate 150 that protrudes from the separator plate 160 of the adjacent power generation unit 100. The convex portion of the separator plate 160 means a portion of the separator plate 160 that protrudes from the separator plate 150 of the adjacent power generation unit 100. Although not shown, the convex top portion 150t of the separator plate 150 is in contact with the bottom 160b of the concave portion between the convex portions of the separator plate 160, and the convex portion 160t of the separator plate 160 is in contact with the convex portion of the separator plate 150. Separator plates 150 and 160 may be formed and arranged so as to come into contact with the bottom 150b of the concave portion between the convex portions.

  FIG. 2 is a plan view of the joined body of the MEA 110 and the resin frame member 140 as viewed from the cathode side. FIG. 3 is a view in which the filling member 195 is omitted from FIG. The resin frame member 140 supports the MEA 110 from the outer edge of the MEA 110. An opening 140k is formed at the center of the resin frame member 140, and the cathode-side gas diffusion layer 120 of the MEA 110 can be seen inside the opening 140k. The cathode-side gas diffusion layer 120 is smaller than the MEA 110, and the outer periphery (outer edge 120 o) of the cathode-side gas diffusion layer 120 is inside the outer periphery of the MEA 110 in plan view. As shown in FIG. 3, there is a gap 186 between the opening 140k and the outer edge 120o of the cathode-side gas diffusion layer 120, and this gap 186 is filled with the adhesive 180 (FIG. 1). Moreover, the protective film 190 is arrange | positioned so that the resin frame member 140 and the cathode side gas diffusion layer 120 may be straddled. In FIG. 2, the adhesive 180 is hidden by the protective film 190 and cannot be seen.

  FIG. 4 is an explanatory diagram showing the area X of FIG. 1 in an enlarged manner. However, in FIG. 4, illustration of the separator plates 150 and 160 described in FIG. 1 is omitted. The MEA 110 includes an electrolyte membrane 111, a cathode side catalyst layer 112, and an anode side catalyst layer 114. The electrolyte membrane 111 is a polymer resin having proton conductivity, and is made of, for example, a perfluorocarbon sulfonic acid polymer.

  The cathode side catalyst layer 112 and the anode side catalyst layer 114 include catalyst-carrying particles and an ionomer. The catalyst-carrying particles are obtained by carrying platinum or a platinum alloy as a catalyst on a carrier such as carbon particles. The ionomer is a polymer resin having proton conductivity, and is formed of a perfluorocarbon sulfonic acid polymer, like the electrolyte membrane 111.

  The anode side catalyst layer 114 is applied over the entire region of the anode side surface of the electrolyte membrane 111, while the cathode side catalyst layer 112 is a part of the rectangular region (power generation region) of the cathode side surface of the electrolyte membrane 111. It is preferable that it is applied only to the surface. This is because the anode-side catalyst layer 114 may have a smaller amount of catalyst per unit area than the cathode-side catalyst layer 112 (typically 1/2 or less, for example, about 1/3). This is because even if the catalyst is applied to the entire region of the membrane 111, it is not excessively wasteful and the coating process is simplified. On the other hand, since the cathode side catalyst layer 112 has a larger amount of catalyst per unit area than the anode side catalyst layer 114, it is possible to reduce useless catalyst by coating only a small area.

  The cathode side gas diffusion layer 120 includes a base material layer 122 and a microporous layer 124. The anode side gas diffusion layer 130 includes a base material layer 132 and a microporous layer 134. The base material layers 122 and 132 are made of, for example, carbon paper or carbon nonwoven fabric. The microporous layers 124 and 134 are formed by kneading fine carbon powder and fluororesin (polytetrafluoroethylene), and are applied to the MEA 110 side of the base material layers 122 and 132, respectively. The cathode side gas diffusion layer 120 is disposed so that the microporous layer 124 is in contact with the cathode side catalyst layer 112, and the anode side gas diffusion layer 130 is disposed so that the microporous layer 134 is in contact with the anode side catalyst layer 114. . Note that the microporous layers 124 and 134 may be omitted.

  The size of the anode side gas diffusion layer 130 is formed to be approximately the same as the size of the electrolyte membrane 111 of the MEA 110. On the other hand, the size of the cathode side gas diffusion layer 120 is smaller than the size of the electrolyte membrane 111 of the MEA 110 in plan view. The cathode-side gas diffusion layer 120 is formed in a shape smaller than the cathode-side catalyst layer 112 in plan view, and is arranged so that the cathode-side gas diffusion layer 120 fits in the region of the cathode-side catalyst layer 112. It is preferable. This is because, when the base material layer 122 of the cathode side gas diffusion layer 120 is formed of carbon paper, the end of the cathode side gas diffusion layer 120 is located at the position of the electrolyte membrane 111 where the cathode side catalyst layer 112 does not exist. This is because carbon fiber fibers may pierce the electrolyte membrane 111 and cause damage to the electrolyte membrane 111 or cross leaks.

  The resin frame member 140 is disposed so as to contact the end portion of the electrolyte membrane 111. A protective film 190 is disposed so as to straddle the surface of the resin frame member 140 and the surface of the cathode side gas diffusion layer 120. The protective film 190 is a resinous film having water resistance and acid resistance, and is formed of, for example, polypropylene (PP), polyethylene naphthalate (PEN), polyphenylene sulfide (PPS), or polyetherimide (PEI). . A gap between the resin frame member 140 and the cathode side gas diffusion layer 120 is filled with an adhesive 180. The adhesive 180 may be made of a material that can be bonded to the resin frame member 140, the cathode side gas diffusion layer 120, and the protective film 190. For example, polyethylene (PE), polystyrene (PS), polyethylene terephthalate (PET). It is formed with the thermoplastic adhesive containing a thermoplastic resin like this.

  The boundary between the adhesive 180 and the MEA 110 constitutes a gas seal line 181 and suppresses leakage of the reaction gas. An adhesive 180 enters between the resin frame member 140 and the protective film 190 to form an adhesive portion 183, and the resin frame member 140 and the protective film 190 are fixed. An adhesive 180 enters between the cathode side catalyst layer 112 and the protective film 190 to form an adhesive portion 184, and the cathode side catalyst layer 112 and the protective film 190 are fixed. Further, the adhesive 180 is cured. Therefore, when a surface pressure is applied to the entire fuel cell stack 10, a surface pressure is applied to the MEA 110 via the cured adhesive 180, so that the MEA 110 (electrolyte film 111) is not deformed, and the film of the electrolyte film 111 is not deformed. Breaking can be suppressed.

  FIG. 5 is a plan view of the filling member 195 as viewed from the adhesive 180 side. 6 is a cross-sectional view of the filling member 195, and is a cross-sectional view taken along the line AA of FIG. The filling member 195 includes a protective film 190 and an adhesive 180. The protective film 190 has a frame shape in which the outer periphery 190o is slightly larger than the opening 140k (FIG. 2) of the resin frame member 140 and the inner opening 190k is slightly smaller than the outer edge 120o of the cathode-side gas diffusion layer 120. It is a member. A frame-shaped adhesive 180 is provided substantially at the center between the outer periphery 190o of the protective film 190 and the opening 190k. The width W of the adhesive 180 before assembly is preferably slightly smaller than the distance between the outer edge 120o of the cathode-side gas diffusion layer 120 and the opening 140k of the resin frame member 140. It is preferable that the height H of the adhesive 180 is slightly larger than the thickness of the cathode side gas diffusion layer 120.

  The filling member 195 can be formed by forming a frame-shaped protective film 190 from a sheet-like film by pressing or the like, and forming the adhesive 180 on the protective film 190 using a thermoplastic adhesive. Since the thermoplastic adhesive is solid at room temperature, the frame-shaped adhesive 180 is easily formed.

  FIG. 7 is an explanatory diagram illustrating a manufacturing process of the power generation unit 100. A resin frame member 140 prepared by disposing the cathode side gas diffusion layer 120 and the anode side gas diffusion layer 130 on both surfaces of the MEA 110 is prepared. Specifically, first, a rectangular electrolyte membrane 111 is formed by an extrusion method. Then, the cathode side catalyst layer 112 and the anode side catalyst layer 114 are respectively formed on both surfaces of the electrolyte membrane 111 by a transfer method to form the MEA 110. Further, the cathode side gas diffusion layer 120 and the anode side gas diffusion layer 130 are disposed on both surfaces of the MEA 110. Thereafter, the resin frame member 140 having the opening 140k is disposed on the cathode side of the MEA 110.

  Next, a separately formed filling member 195 is arranged so that the adhesive 180 is inserted into the gap 186 between the cathode side gas diffusion layer 120 and the resin frame member 140. Next, the filling member 195 is heated using the hot press machine 200 to melt the adhesive 180. A part of the adhesive 180 enters between the protective film 190 and the resin frame member 140 and between the protective film 190 and the cathode-side gas diffusion layer 120 to form adhesive portions 183 and 184, respectively. Thereafter, the adhesive 180 is cured by cooling to fill the gap 186, and adhere and fix between the protective film 190 and the resin frame member 140 and between the protective film 190 and the cathode side gas diffusion layer 120. . The adhesive 180 also adheres to the electrolyte membrane 111 and the cathode side catalyst layer 112 to form a seal line 181 (FIG. 4).

  FIG. 8 is an explanatory diagram showing a power generation unit 101 of a comparative example. In the power generation unit 101 of the comparative example, the resin frame member 140 and the electrolyte membrane 111 of the MEA 110 are bonded with an adhesive 187. In the power generation unit 101 of the comparative example, the gap 186 between the cathode side gas diffusion layer 120 and the resin frame member 140 is not sufficiently filled with the adhesive 187. In this configuration, since the surface pressure of the fuel cell stack 10 is not applied to the MEA 110 via the adhesive 187, the MEA 110 (electrolyte membrane 111) may be deformed to protrude toward the gap and may be damaged.

  According to the first embodiment, the adhesive 180 sufficiently fills the gap 186 formed between the cathode side gas diffusion layer 120, the resin frame member 140, the MEA 110, and the protective film 190. A surface pressure can be applied to the MEA 110 via 180. As a result, the MEA 110 (electrolyte membrane 111) can be hardly deformed and broken toward the gap 186.

  Further, according to the first embodiment, since the adhesive 180 is covered with the protective film 190, the cured adhesive 180 is applied from the plane formed by the cathode side gas diffusion layer 120 or the resin frame member 140. Does not protrude outwardly (upward in FIG. 4). Therefore, there is an advantage that undesirable excessive unevenness does not occur when the fuel cell stack 10 is formed.

Second embodiment:
FIG. 9 is an explanatory diagram showing the power generation unit 102 of the second embodiment and its manufacturing process. In the power generation unit 100 of the first embodiment, the resin frame member 140 has a shape in contact with the cathode side surface of the MEA 110. However, in the power generation unit 102 of the second embodiment, the resin frame member 140 is The difference is that it is not in contact with the surface of the MEA 110 and is arranged outside the outer periphery of the MEA 110. Therefore, the gap 186 is not only between the resin frame member 140 and the cathode side gas diffusion layer 120 and between the resin frame member 140 and the MEA 110, but also between the resin frame member 140 and the anode side gas diffusion layer 130. Also occurs.

  In the second embodiment, the power generation unit 102 is formed as follows. The process of forming the MEA 110 is the same as that described with reference to FIG. Next, the cathode side gas diffusion layer 120 and the anode side gas diffusion layer 130 are disposed on the MEA 110, and the resin frame member 140 is disposed around the cathode side gas diffusion layer 120 and the anode side gas diffusion layer 130. Thereafter, a separately formed filling member 195 is disposed so that the adhesive 180 is inserted into the gap 186 between the cathode side gas diffusion layer 120 and the resin frame member 140. Next, the filling member 195 is heated using the hot press machine 200 to melt the adhesive 180. Part of the adhesive 180 enters between the protective film 190 and the resin frame member 140 and between the protective film 190 and the cathode-side gas diffusion layer 120 to form adhesive portions 183 and 184, respectively. The adhesive 180 also fills a part between the resin frame member 140 and the anode side gas diffusion layer 130. Thereafter, the adhesive 180 is cooled and cured.

  Also in the second embodiment, since the adhesive 180 fills the gap 186 formed between the cathode side gas diffusion layer 120, the resin frame member 140, the MEA 110, and the protective film 190, the fuel cell stack 10 The surface pressure can be applied to the MEA 110 via the adhesive 180, and the MEA 110 (electrolyte membrane 111) can be hardly deformed and broken toward the gap 186.

  In the first and second embodiments, a thermoplastic adhesive containing a thermoplastic resin is used as the adhesive 180. However, a thermosetting resin such as an epoxy resin or a phenol resin, or polyisobutylene (PIB) is used. An adhesive containing an ultraviolet curable resin may be used.

  The embodiments of the present invention have been described above based on some examples. However, the above-described embodiments of the present invention are for facilitating the understanding of the present invention and limit the present invention. It is not a thing. The present invention can be changed and improved without departing from the spirit and scope of the claims, and it is needless to say that the present invention includes equivalents thereof.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell stack 100 ... Power generation unit 101 ... Power generation unit 102 ... Power generation unit 110 ... Membrane electrode assembly 111 ... Electrolyte membrane 112 ... Cathode side catalyst layer 114 ... Anode side catalyst layer 120 ... Cathode side gas diffusion layer 120o ... (Cathode) Outer edge 122 of the side gas diffusion layer 122: Base layer 124 ... Microporous layer 130 ... Anode side gas diffusion layer 132 ... Base layer 134 ... Microporous layer 140 ... Resin frame member 140k ... Opening 150 ... Separator plate 150b ... Bottom 150t ... top 155 ... cathode gas flow path 160 ... separator plate 160b ... bottom 160t ... top 165 ... anode gas flow path 175 ... refrigerant flow path 180 ... adhesive 181 ... gas seal line 183 ... adhesion 184 ... adhesion 186 ... gap 187 ... Adhesive 1 0 ... protective film 190k ... (protective film) opening 190O ... (protective film) periphery 195 ... filling member 200 ... heat press H ... Height W ... width X ... region

Claims (1)

A fuel cell,
A membrane electrode assembly;
Two gas diffusion layers arranged on both surfaces of the membrane electrode assembly, wherein one gas diffusion layer of the two gas diffusion layers is smaller than the membrane electrode assembly, and the one in the plan view Two gas diffusion layers in which the outer periphery of the gas diffusion layer is inside the outer periphery of the membrane electrode assembly,
A resin frame member disposed with a gap around the outer periphery of the one gas diffusion layer;
A protective film disposed across the resin frame member and the one gas diffusion layer on the surface opposite to the membrane electrode assembly of both surfaces of the one gas diffusion layer;
An adhesive that fills a gap formed between the resin frame member, the gas diffusion layer, the membrane electrode assembly, and the protective film;
A fuel cell comprising:

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