JP2014120212A - Polymer electrolyte type fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymer electrolyte type fuel cell which can perform miniaturization of stack without reducing an effective area for an electrode reaction, reduce shortcut of gas, increase a utilization efficiency and increase a power generation efficiency.SOLUTION: A frame pinching a peripheral portion of a polymer electrolyte membrane has an electrode-side projection projecting to the inside of an electrode layer, and at least one electrode-side projection is disposed so as to come into contact with the ridge of a turning portion at which gas counter-flows in adjacent passage grooves of the separator.

Description

  The present invention relates to a fuel cell used for a portable power source, an electric vehicle power source, a household cogeneration system, or the like, and more particularly to a polymer electrolyte fuel cell.

  A fuel cell using a polymer electrolyte generates electric power and heat simultaneously by electrochemically reacting a fuel gas containing hydrogen and an oxidant gas containing oxygen such as air.

  This fuel cell basically includes a polymer electrolyte membrane that selectively transports hydrogen ions and a pair of electrodes formed on both sides of the polymer electrolyte membrane, that is, an anode and a cathode. These electrodes are mainly composed of carbon powder supporting a platinum group metal catalyst, and have both a gas permeability and an electronic conductivity disposed on the outer surface of the catalyst layer formed on the surface of the polymer electrolyte membrane and the catalyst layer. It has a gas diffusion layer.

  An assembly in which the polymer electrolyte membrane and the electrode (including the gas diffusion layer) are integrally joined together is called an electrolyte membrane electrode assembly (hereinafter referred to as “MEA”).

  In addition, on both sides of the MEA, conductive separators are disposed for mechanically sandwiching and fixing the MEAs and electrically connecting adjacent MEAs in series with each other. In each separator, a flow channel for supplying a reaction gas such as a fuel gas or an oxidant gas to each electrode and carrying away generated water or surplus gas is formed in a portion that contacts the MEA.

  Such a gas flow path can be provided separately from the separator, but a system in which a groove is provided on the surface of the separator to form a gas flow path is generally used.

  In such a fuel cell, the gas diffusion layer has a function of smoothly moving the reaction gas from the gas flow path to the catalyst layer and discharging a reaction product such as product gas or water to the flow path groove. At the same time, when viewed in the plane direction of the battery, it also serves as a shortcut route for the reaction gas, which causes a reduction in gas utilization.

  A conventional fuel cell includes, for example, a single cell in which an electrolyte membrane is sandwiched between a fuel electrode and an oxidant electrode, and a plurality of parallel grooves for supplying fuel fluid to the fuel cell as described in Patent Document 1. A fuel cell comprising a laminate in which an oxidant fluid is supplied to the fuel parallel flow path group and the oxidant electrode, and a separator in which the oxidant parallel flow path group including a plurality of parallel grooves folds and travels is sequentially stacked. known. Then, the width of the ridges between the adjacent parallel flow channel groups is larger than the width of the ridges between the grooves in the parallel flow channel group so as to reduce the gas shortcut in the separator flow channel.

  In addition, as a configuration of the fuel cell, there is a problem that a cross leak phenomenon is likely to occur from a minute gap between the polymer electrolyte membrane and the frame in the joining method in which the MEA is mechanically sandwiched and fixed.

  Here, FIG. 9 is a schematic view of a cross section of an electrode-membrane-frame assembly provided in a conventional fuel cell stack. 106 is an electrolyte membrane, and 110 is a catalyst layer, which are provided on both sides of the polymer electrolyte membrane 106. 108 is an oxidant gas diffusion layer, 109 is a fuel gas diffusion layer, and is provided outside the catalyst layer 110. Reference numeral 112 denotes a frame, and a small gap 107 generated between the inner edge of the frame 112 and the catalyst layer 110 passes through a part of the gas supplied into the battery to either the fuel gas side or the oxidant gas side. The phenomenon that gas leaks is called cross leak.

  In order to increase the power generation efficiency in the fuel cell, it is necessary to reduce such cross leakage.

  FIG. 10 is a plan view of the separator as viewed from the fuel gas diffusion layer side of the conventional fuel cell described in Patent Document 2. FIG. The separator 10 has a shape of a reaction effective region H × L in which the flow channel 5a is engraved. In the main traveling portion 51 located on the upstream side and the downstream side of the folded portion 52 of the flow channel groove 5a, the fuel gas flows in opposite directions. There has been proposed a separator characterized in that the length in the direction in which the folded portion 52 is arranged is longer than the length in the direction along the main traveling portion 51 of the flow channel.

  FIG. 11 shows a partial schematic diagram of the electrode-membrane-frame assembly in Patent Document 3. As shown in FIG.

  In the electrode-membrane-frame assembly of Patent Document 3, the frame body 118 is disposed on the cathode surface side of the peripheral edge portion 106a of the polymer electrolyte membrane 106, and the convex portion 118a and the concave portion 118b are alternately arranged on the end surface portion. It is formed in a comb-tooth shape, and a frame body 119 is disposed on the anode surface side, and a convex-shaped portion 119a and a concave-shaped portion 119b are alternately formed in a comb-tooth shape on the end surface portion.

  At this time, the shape of the frame on the anode surface side corresponding to the boundary of the polymer electrolyte membrane 106 in the convex portion 118a of the cathode surface side frame body is a concave shape 119b, and the concave portion 118b of the cathode surface side frame body. The frame shape on the anode surface side corresponding to the boundary of the polymer electrolyte membrane 106 is a convex shape 119a.

  FIG. 12 shows a schematic diagram of the electrode-membrane-frame assembly of Patent Document 3 in a state where an elastic body is installed in the concave portion of the frame comb-tooth portion.

  The polymer electrolyte membrane 106 is not covered with the anode, the cathode, and the frame body 118, and the portion where the membrane itself is exposed to the outside, that is, the polymer electrolyte membrane between the convex portions 118a of the cathode side frame body The peripheral edge part 106a of 106 is covered with the elastic body 120, and such an electrolyte membrane-electrode assembly (MEA) is used.

JP 2001-76746 A JP 2005-276508 A JP 2009-238757 A

  However, in the conventional configuration described above, in the control of the width of the groove between the grooves shown in Patent Document 1, if the width of the wall is excessively wide in order to eliminate the gas shortcut as much as possible, the reaction gas is diffused into the catalyst layer in this portion. There is a problem that it becomes difficult and does not function effectively as an electrode reaction surface.

  Moreover, in the structure shown in patent document 2, since restrictions are provided in the aspect ratio of a separator, it has the subject that stack size reduction is difficult.

  Even in the configuration shown in Patent Document 3, a cross leak occurs in the peripheral portion 106 a of the polymer electrolyte membrane 106 that is not covered with the elastic body 120.

  The present invention solves the above-mentioned conventional problems, and eliminates gas shortcuts and cross-leakage phenomena that do not reduce the effective area of the electrode reaction in a polymer electrolyte fuel cell and that can realize stack miniaturization. An object of the present invention is to provide a polymer electrolyte fuel cell that can reduce the gas utilization efficiency and increase the power generation efficiency.

In order to achieve the above object, the present invention provides a fuel gas-side electrode layer and an oxidant gas-side electrode layer on both surfaces inside the periphery of the polymer electrolyte membrane, and the both electrode layers are A polymer electrolyte type in which a plurality of unit cell modules are formed by sandwiching a fuel gas side electrode layer and an oxidant side electrode layer with separators each having a flow channel for supplying fuel gas and oxidant gas. In fuel cells,
The frame that sandwiches the periphery of the polymer electrolyte membrane has an electrode-side protrusion that protrudes inside the electrode layer, and the electrode-side protrusion is opposed to the gas in a channel groove adjacent to the separator. There is provided a polymer electrolyte fuel cell, wherein at least one is disposed so as to abut against a fold of the folded-back portion flowing.

  As described above, according to the polymer fuel cell of the present invention, it is possible to reduce shortcuts, and further, the protrusions are in contact with the separator and compressed, thereby crossing the gap between the frame and the polymer electrolyte membrane. It is possible to provide a polymer electrolyte fuel cell that can reduce the leak phenomenon, increase the gas utilization efficiency, and increase the power generation efficiency.

The exploded perspective view of the fuel cell of the present invention The top view of the oxidant side separator seen from the oxidant gas diffusion layer side of the fuel cell of the present invention (A) It is a perspective view of the protrusion of the fuel cell in Embodiment 1 of this invention, (b) The top view of the frame body contact | abutted to the separator of the fuel cell in Embodiment 1 of this invention Sectional drawing of the cell module in AA of FIG. Sectional drawing of the cell module in DD of FIG. The perspective view of the protrusion of the fuel cell in Embodiment 2 of this invention FIG. 6 is a partial cross-sectional view of the frame shown in FIG. 6 assembled as a fuel cell. Arrangement plan view of the fuel side separator viewed from the fuel gas diffusion layer side of the fuel cell in Embodiment 3 of the present invention Schematic diagram of a cross section of an electrode-membrane-frame assembly provided in a conventional fuel cell stack The top view which looked at the fuel gas side separator from the fuel gas diffusion layer side of the conventional fuel cell described in patent documents 2 Partial schematic diagram of conventional electrode-membrane-frame assembly (without elastic member) Partial schematic diagram of conventional electrode-membrane-frame assembly (with elastic member)

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
First, the overall configuration of the polymer electrolyte fuel cell of the present invention will be described.

  FIG. 1 is an exploded perspective view of a fuel cell according to the present invention.

  As shown in FIG. 1, a fuel cell stack 30 includes a cell stack 20 in which a plurality of unit cell modules (cells) 1 are stacked at the center thereof. In addition, the current collector plate 2 and the end plate 3 having a large number of inner springs 4 as an example of an elastic body are disposed on the outermost layers at both ends of the cell stack 20.

  The four fastening bolts 7 fitted with the outer springs 5 are connected to the current collector plate 2 and the end plate opposite to the end plate 3, the current collector plate 2, and the cell laminate 20 from one end of the cell laminate 20. 3 is configured to pass through the bolt holes 6 at the respective corners with the nut 3 and be fastened with nuts 8. In addition, a fastening member is not restricted to what is comprised with the fastening bolt 7 and the nut 8, Other structures, such as a fastening band, may be sufficient.

  The current collector plate 2 is disposed on the outside of the cell stack 20, and a copper plate with gold plating is used so that the generated electricity can be collected efficiently. Note that the current collector plate 2 may be made of a metal material having good electrical conductivity, such as iron, stainless steel, or aluminum. Further, the surface treatment of each current collector plate 2 may be performed with tin plating, nickel plating, or the like.

  An end plate 3 using an electrically insulating material is disposed outside each current collecting plate 2 to insulate electricity, and also serves as an insulating function. The end plate 3 is preferably manufactured by injection molding using a glass fiber-containing polyphenylene sulfide resin from the viewpoint of strength and heat resistance. Each pipe 3 a integrated with the end plate 3 is pressed against each manifold of the cell stack 20 via a gasket (not shown) that functions as a manifold seal member and has a manifold through hole. It is configured to communicate.

  Inside each end plate 3, the numerous inner springs 4 that apply a load to the cell 1 are projected portions of a polymer electrolyte membrane electrode assembly (hereinafter referred to as “MEA”) 9, that is, the cell 1. The tightening dimensions are managed so that a predetermined load is applied to the cell stack 20 in a tightened state while being uniformly and uniformly arranged inside. The outer spring 5 is disposed between the head of each fastening bolt 7 and the outer surface of the end plate 3, and is adjusted and fastened by a plurality of fastening bolts 7 and a plurality of nuts 8 during assembly.

  The cell 1 includes an MEA 9 having a frame body 14 at a peripheral edge, and is sandwiched between a pair of conductive separators 10, specifically, a fuel-side separator 10a and an oxidant-side separator 10c, and one separator such as an oxidant-side separator 10c. The cooling water separator 10w is arranged on the outer side. A pair of through-holes through which fuel gas, oxidant gas, and cooling water circulate are provided in the frame 14 disposed on the peripheral edge of the fuel side separator 10a and the oxidant side separator 10c, the cooling water separator 10w, and the MEA 9. That is, the manifold hole 11 is provided.

  In the state of the cell stack 20 in which a plurality of cells 1 are stacked, the manifold holes 11 are stacked and communicated with each other to form a fuel gas manifold, an oxidant gas manifold, and a cooling water manifold.

  The MEA 9 includes a polymer electrolyte membrane that selectively transports hydrogen ions, and a pair of electrode layers formed on both sides of the polymer electrolyte membrane, that is, a portion inside the peripheral portion, that is, an electrode layer of fuel gas and oxidant gas. It is made up of. The electrode layer has a laminated structure having a gas diffusion layer and a catalyst layer disposed between the gas diffusion layer and the polymer electrolyte membrane.

  The fuel-side separator 10a and the oxidant-side separator 10c have a flat plate shape, and the surface on the side in contact with the MEA 9, that is, the inner surface has a shape corresponding to the shape of the MEA 9 and the frame body 14, respectively. Yes. In each separator 10, various manifold holes 11 and bolt holes 6 penetrate each separator 10 in the thickness direction.

  A fuel gas channel groove 12a is formed on the inner surface of the fuel side separator 10a, and an oxidant gas channel groove 12c is formed on the inner surface of the oxidant side separator 10c. A cooling water passage groove 12w is formed on the side surface. Various manifold holes 11, bolt holes 6, fuel gas flow channel grooves 12a, oxidant gas flow channel grooves 11c, and cooling water flow channel grooves 12w are formed by cutting or molding.

  The frame 14 disposed around the MEA 9 is made of resin and is integrally formed with the MEA 9. Each separator 10 is provided with a gasket (not shown). By this gasket, a fuel gas and an oxidant gas are provided between adjacent cells 1 and between the separator 10 and the frame 14 inside the cell 1 and between the separators 10. And leakage of the cooling water is prevented.

  A feature of the present invention is that it has an electrode-side protrusion that protrudes to the inside of the electrode layer, and the electrode-side protrusion is in contact with the fold of the folded portion where the gas flows oppositely in the adjacent channel groove of the separator. , At least one is arranged.

  The operation regarding the location of the protrusion, its shape, the compression deformation of the protrusion and gas diffusion layer during cell assembly, and the flow of fuel gas and oxidant gas will be described in order.

  The place where the protrusion is located will be described.

  2, 3, 4, and 5 are diagrams for explaining the polymer electrolyte fuel cell according to Embodiment 1 of the present invention.

  FIG. 2 is a plan view of the oxidant side separator viewed from the oxidant gas diffusion layer side of the fuel cell of the present invention. In FIG. 2, the oxidant side separator 101 (corresponding to 10 c in FIG. 1) includes an inlet manifold 102 and an outlet manifold 103. Six flow path grooves 104 are folded and traveled from the inlet manifold 102 to the outlet manifold 103, and gas is configured to flow from one end to the other end of the flow path groove 104. Note that the number of the channel grooves 104 is an example, and is not limited to six.

  The position of the outer edge of the polymer electrolyte membrane 106 projected onto the oxidant side separator 101 is indicated by a two-dot chain line, the outer edge of the catalyst layer 110 is indicated by a broken line, and the position of the gasket 115 is indicated by a thick solid line.

  In FIG. 2, the path on which the oxidant gas is short-circuited is a path that is short-circuited from the point B to the point C in the adjacent channel groove portion as indicated by an arrow. More specifically, the solid line arrow is the path where the oxidant gas diffusion layer is exposed, and the broken line arrow is the path where the oxidant gas diffusion layer is covered with the frame. The arrangement position 105 of the frame protrusion is preferably parallel to the longitudinal direction of the flow channel 104 (cross section AA) between the points B and C in the flow channel.

  This is because the gas flow is opposite at the folded portion between the point B and the point C, and further, a gas concentration difference is generated from the upstream side of the inlet manifold 102 to the downstream side of the outlet manifold 103. This is because the difference in gas concentration becomes large at the folded portion between them.

  Further, at point B where the oxidant gas bends the flow direction at a right angle, a drift occurs such that the flow velocity outside the inside becomes faster. The influence of the drift current is the largest at the bent part and becomes smaller as it goes downstream. According to the simulation, the influence of the drift is up to 20 times the width of the channel groove, and the drift is 2% or less at 5 times the width of the channel groove and 0.5% or less at 10 times.

  The shape of the protrusion will be described.

  3A is a perspective view of a protrusion, and FIG. 3B is a plan view of a frame corresponding to a circled portion in FIG.

  3A, reference numeral 108 denotes an oxidant gas diffusion layer, which corresponds to the surface of the MEA 9 in FIG. Reference numeral 112 denotes a frame, which corresponds to the frame 14 in FIG. Reference numeral 113 denotes a frame protrusion on the oxidant side, and is arranged so as to cover the entire outer edge of the oxidant gas diffusion layer 108. The outer edge of the oxidant side frame protrusion 113 is arranged to be inside the gasket 115.

  In the oxidant side frame protrusion 113, an electrode side protrusion 113a protruding inward of the electrode layer is located at the position 105 of the frame protrusion shown in FIG. ) In parallel.

  In FIG. 3A, the thickness T1a is more than 0, preferably 0.8 times or less of the thickness of the oxidant gas diffusion layer 108, and more preferably less than the porosity of the oxidant gas diffusion layer 108. . When the thickness exceeds the porosity, the catalyst layer is compressed and the power generation efficiency decreases. The width W1 of the electrode-side protrusion 113a is less than the width of the folded portion of the flow channel groove and is preferably equal to or greater than the thickness T1a. When the width is greater than or equal to the width of the folded portion of the flow channel groove, the power generation efficiency is lowered, and when the thickness is less than T1a, the layer tends to collapse when being laminated.

  113b is a protrusion in the stacking direction, and is disposed on the extension of the electrode-side protrusion 113a. The thickness T1b of the protrusion 113b in the stacking direction is obtained by adding a gap between the oxidant side separator and the oxidant side frame protrusion 113 described later to the thickness T1a.

  Similarly, the fuel-side protrusion is not shown, but the thickness T2a of the electrode-side protrusion 114a is preferably greater than 0 and not more than 0.8 times the thickness of the oxidant gas diffusion layer 108. Further, the fuel gas diffusion layer 109 The porosity is preferably below. When the thickness exceeds the porosity, the catalyst layer is compressed and the power generation efficiency decreases. The width W2 of the electrode-side protrusion 114a is less than the width of the folded portion of the flow channel groove and is preferably equal to or greater than the thickness T2a. When the width is greater than or equal to the width of the folded portion of the flow channel groove, the power generation efficiency is lowered.

  Similarly, although the fuel side protrusion 114 is not shown, 114b is a protrusion in the stacking direction and is arranged on the extension of the electrode side protrusion 114a. The thickness T2b of the protrusion 114b in the stacking direction is obtained by adding a gap between a fuel-side separator and a fuel-side frame protrusion 114 described later to the thickness T2a.

  The material of the oxidant side frame protrusion 113, the electrode side protrusion 113a, and the protrusion 113b in the stacking direction is preferably high chemical resistance polypropylene or silicon resin. Can be lowered. When a material different from that of the frame body 112 is used, warpage of the frame body 112 can be suppressed by using a material having a lower elastic modulus than that of the frame body 112, and when the elastic modulus is higher than that of the oxidant gas diffusion layer 108, The gas diffusion layer is easily compressed and deformed.

  In FIG. 3B, the outer edge of the polymer electrolyte membrane 106 is indicated by a two-dot chain line, the outer edge of the catalyst layer 110 is coincident with the outer edge of the oxidant gas diffusion layer 108, the position thereof is indicated by a broken line, and the position of the gasket 115 is indicated. It is shown by a thick solid line.

  Actions relating to the electrode side protrusion, the protrusion in the stacking direction, the compression deformation of the gas diffusion layer, and the flow of fuel gas and oxidant gas during cell assembly will be described in order.

  4 is a cross-sectional view of the unit cell module taken along the line AA of FIG. A catalyst layer 110 is formed on both surfaces of the polymer electrolyte membrane 106, and an oxidant gas diffusion layer 108 and a fuel gas diffusion layer 109 are formed on the outer sides thereof. These layers form an oxidant gas side electrode layer 116 and a fuel gas side electrode layer 117, respectively. There is no.

  The peripheral portion of the polymer electrolyte membrane 106 is sandwiched by a frame body 112 made of a resin material. The oxidant side separator 101 is in contact with the oxidant gas diffusion layer 108 side, and the fuel side separator 111 is in contact with the fuel gas diffusion layer 109 so that the catalyst layer 110 is sandwiched therebetween.

  The gasket 115 is a sealing member made of an elastic body, and the gasket 115 is compressed and deformed by pressing of the frame body 112, the oxidant side separator 101, and the fuel side separator 111. As the gasket 115 is compressed and deformed, the electrode-side protrusion 113a and the protrusion 113b in the stacking direction abut against the oxidant-side separator 101, and the oxidant gas-side electrode layer 116 under the electrode-side protrusion 113a and the protrusion 113b in the stacking direction. Is compressed. When the electrode-side protrusion 113a, the protrusion 113b in the stacking direction, and the oxidant-side frame protrusion 113 are made to have a higher elastic modulus than the oxidant gas diffusion layer 108, the oxidant gas diffusion layer 108 is mainly compressed. The Since the vacancies in the oxidant gas diffusion layer 108 are blocked, the oxidant gas shortcut can be reduced.

  In particular, since the oxidant gas diffusion layer under the electrode-side protrusion 113a is compressed, the holes are closed in a band shape. At point B in FIG. 2 where the oxidant gas bends the flow direction at a right angle, a drift occurs such that the flow velocity outside the channel groove 104 becomes faster than the inside, and the oxidant gas moves from point B to point C in FIG. And a shortcut to try to pass through the gas diffusion layer indicated by the solid arrow. Since the vacancies in the gas diffusion layer under the electrode-side protrusion 113a are blocked, it is possible to reduce shortcuts that try to pass through the gas diffusion layer.

  The length L1 from the center of the flow channel groove 104 to the tip of the electrode-side protrusion 113a is preferably 0.5 times or more the width of the flow channel groove and remains 20 times the effect of drift, and the effect of drift is further reduced. An efficiency of 5 to 10 times the width of the channel groove is efficient.

  The protrusions 113b in the stacking direction also block the vacancies in the oxidant gas diffusion layer 108 covered with the resin, and the oxidant gas diffusion layer extends from point B to point C in FIG. Can reduce the number of shortcuts.

  Note that the oxidant gas diffusion layer 108 can be closed by applying the oxidant side separator 101 to the slopes and skirts between the electrode side protrusions 113a and the protrusions 113b in the stacking direction, and the oxidant gas shortcut can be reduced. .

The fuel gas side is the same as the oxidant gas side,
As the gasket 115 is compressed and deformed, the electrode side protrusion 114a and the protrusion 114b in the stacking direction abut against the fuel side separator 111, and the fuel gas side electrode layer 117 under the electrode side protrusion 114a and the protrusion 114b in the stacking direction is compressed. Is done. When the electrode-side protrusion 114a, the protrusion 114b in the stacking direction, and the fuel-side frame protrusion 114 have a higher elastic modulus than the fuel gas diffusion layer 109, the fuel gas diffusion layer 109 is mainly compressed when stacking. Since the holes in the fuel gas diffusion layer 109 are closed, the fuel gas shortcut can be reduced.

  In particular, since the fuel gas diffusion layer under the electrode-side protrusion 114a is compressed, the pores are closed like a band. In the folded portion where the flow direction of the fuel gas is bent at a right angle, a drift occurs such that the flow velocity outside the flow channel 104 becomes faster than the inside, and the fuel gas flows in the folded portion corresponding to the point C from the point B in FIG. Shortcuts that tend to pass through the gas diffusion layer are likely to occur. Since the vacancies in the gas diffusion layer below the electrode-side protrusion 114a are blocked, the shortcut of fuel gas that tries to pass through the gas diffusion layer can be reduced.

  The length L2 from the center of the channel groove 104 to the tip of the electrode side projection 114a is preferably 0.5 times or more the width of the channel groove and remains 20 times the effect of drift, and the effect of drift is further reduced. An efficiency of 5 to 10 times the width of the channel groove is efficient.

  The protrusion 114b in the stacking direction also closes the holes of the fuel gas diffusion layer 109 covered with the resin, and the fuel gas shortcut can be reduced.

  It is to be noted that the fuel gas diffusion layer 109 can be closed by applying the fuel side separator 111 to the slope and the skirt between the electrode side protrusion 114a and the protrusion 114b in the stacking direction, and the fuel gas shortcut can be reduced.

  Therefore, the utilization efficiency of oxidant gas and fuel gas can be improved, and power generation efficiency can be improved.

  In FIG. 4, the electrode-side protrusion 113a on the oxidant gas side and the protrusion 113b in the stacking direction, and the electrode-side protrusion 114a on the fuel gas side and the protrusion 114b in the stacking direction are shown, but only one surface may be used.

  FIG. 5 is a cross-sectional view of the cell module taken along the line DD of FIG. The description of the same parts as in FIG. 4 is omitted. The difference from FIG. 2 is that there are no electrode-side projections 113a and 114a and projections 113b and 114b in the stacking direction, and the oxidant-side frame projection 113 is not in contact with the oxidant-side separator 101 and has the aforementioned gap. Similarly, the fuel side frame projection 114 is not in contact with the fuel side separator 111 and has a gap. This is because the flow path folding portion can be efficiently pressed even with a small pressing force that the frame projection and the separator are not in contact with each other.

(Embodiment 2)
FIG. 6 is a perspective view of the protrusion of the fuel cell according to Embodiment 2 of the present invention.

  The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The difference from the first embodiment is that the protrusion 113b in the stacking direction spreads and is integrated with the oxidant side frame protrusion 113.

  When the frame 112 is sandwiched between the separators and pressed, the oxidant side frame projection 113 and the fuel side frame projection 114 are compressed and deformed. The oxidant gas side electrode layer 116 and the fuel gas side electrode layer 117 are also compressed and deformed, and the end surfaces of both catalyst layers 110 swell outward to fill the gap 107. The shape when compressed and deformed is indicated by a two-dot chain line.

  FIG. 7 is a partial cross-sectional view of the state where the frame shown in FIG. 6 is assembled as a fuel cell, and corresponds to the position at A-A in FIG.

  The height of the protrusion 113b in the stacking direction of the oxidant side frame protrusion 113 from the polymer electrolyte membrane 106 is H1, and the gasket 115 is deformed by pressing of the frame 112, the oxidant side separator 101, and the fuel side separator 111. After that, the height is H2, and the relationship is H1> H2. The fuel side frame protrusion 114 and the protrusion 114b in the stacking direction are similarly compressed and deformed. In addition, a broken line shows the position before compressing.

  According to such a configuration, the oxidant-side stacking direction projection 113b and the fuel-side stacking direction projection 114b are in contact with the oxidant-side separator 101 and the fuel-side separator 111, respectively, and are compressed. A slight gap 107 generated between the inner edge and the end of the catalyst layer 110 can be eliminated by the end surface of the catalyst layer 110 bulging outward.

  A cross-leak phenomenon in which part of the gas supplied into the fuel cell leaks from one of the fuel gas side or the oxidant gas side to the other through the polymer electrolyte membrane 106 in the gap 107 that does not contribute to power generation. Can be reduced. Therefore, the utilization efficiency of oxidant gas and fuel gas can be improved, and power generation efficiency can be improved.

(Embodiment 3)
FIG. 8 is an arrangement plan view of the fuel-side separator as viewed from the fuel gas diffusion layer side of the fuel cell of the present invention. The position of the outer edge of the polymer electrolyte membrane 106 projected onto the fuel side separator 111 is indicated by a two-dot chain line, the outer edge of the catalyst layer 110 is indicated by a broken line, and the position of the gasket 115 is indicated by a thick solid line.

  In FIG. 8, the same components as those in FIG. The difference is that the flowing gas is hydrogen, and that the flow channel 104 is folded more than the oxidant side separator of FIG.

  In general, a chemical reaction occurring in a fuel cell is represented by the following reaction formula.

H ₂ + (1/2) O ₂ → H ₂ O
The fuel gas containing hydrogen requires a larger volume than the oxidant gas.

  Further, hydrogen has a lower viscosity than air flowing as an oxidant gas. In order to make the pressure loss of the gas on the fuel electrode side and the oxidant electrode side of the fuel cell the same, it is preferable that the flow path groove 104 of the fuel electrode side separator 111 is more folded than the oxidant side separator.

  In FIG. 8, the arrangement positions 105 of the projections of the frame body are shown in all of the folding of the flow channel grooves 104 of the fuel electrode side separator 111, but the arrangement positions 105 a of the projections closest to the outlet manifold 103 It is preferable to provide electrode-side protrusions on the fuel-side frame protrusions. Since the short-cut hydrogen gas can be reduced from the outlet manifold 103 as off-gas, the fuel gas utilization efficiency can be increased and the power generation efficiency can be increased.

  The polymer electrolyte fuel cell of the present invention is useful as a polymer electrolyte fuel cell used for a portable power source, an electric vehicle power source, a household cogeneration system, or the like.

  Further, the present invention can be applied to a direct methanol fuel cell (DMFC) that uses methanol instead of the fuel gas that provides hydrogen.

10c, 101 Oxidant side separator 102 Inlet manifold 103 Outlet manifold 5a, 104 Channel groove 105 Arrangement position of frame protrusion 106 Polymer electrolyte membrane 107 Gap 108 Oxidant gas diffusion layer 109 Fuel gas diffusion layer 110 Catalyst layer 10a, 111 Fuel Side Separator 14, 112, 118, 119 Frame 113 Oxidant Side Frame Projection 114 Fuel Side Frame Projection 115 Gasket 116 Oxidant Gas Side Electrode Layer 117 Fuel Gas Side Electrode Layer

Claims (4)

The electrode layer for fuel gas is disposed on one surface inside the outer periphery of the polymer electrolyte membrane, the electrode layer for oxidant gas is disposed on the other surface, the electrode layer for fuel gas, and the electrode layer for oxidant gas, A polymer electrolyte in which a plurality of unit cell modules, each of which is sandwiched between separators each having a flow channel for supplying fuel gas and oxidant gas to each of the electrode layer for fuel gas and the electrode layer for oxidant gas, are stacked Type fuel cell,
It has a frame that sandwiches the polymer electrolyte membrane around the polymer electrolyte membrane,
The frame has one or more protrusions projecting inward of the frame, and the protrusions come into contact with the folds of the folded portions where the gas flows adjacent to the flow channel in the separator. Being arranged in the
A polymer electrolyte fuel cell.   2. The polymer electrolyte mold according to claim 1, wherein a protrusion in a stacking direction of the unit cell module is disposed on an extension of a protrusion protruding inside the frame so that the frame and the separator are in contact with each other. Fuel cell.   2. The polymer electrolyte fuel cell according to claim 1, further comprising a protrusion that contacts the separator with the frame.   The polymer electrolyte fuel cell according to claim 1, wherein the number of protrusions disposed on the fuel gas side is greater than the number of protrusions disposed on the oxidant gas side.

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