JP4360118B2 - Fuel cell - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel battery cell used as a power generator for automobiles, mobile communication devices, household power generation systems, and the like, and more particularly to a fuel battery cell using a polymer electrolyte.
[0002]
[Prior art]
As shown in FIG. 17, the polymer electrolyte fuel cell has a structure in which a polymer electrolyte membrane 71 is sandwiched from both sides by an anode 72 and a cathode 73. The anode 72 includes a gas diffusion layer 74 and a catalyst layer 76. The cathode 73 is composed of a gas diffusion layer 75 and a catalyst layer 77. On the anode 72 side, hydrogen ions (protons) and electrons are generated from the hydrogen gas supplied through the gas diffusion layer 74 by the catalyst layer 76, and the hydrogen ions move in the polymer electrolyte membrane 71 to the cathode 73 side. On the cathode 73 side, oxygen gas supplied through the gas diffusion layer 75 and electrons supplied to the cathode 73 through an external circuit react to generate water. At this time, the reaction on the anode 72 side and the reaction on the cathode 73 side are as follows.
Anode 72 side H ₂ → 2H ⁺ + 2e ⁻
Cathode 73 side (1/2) O ₂ + 2H ⁺ + 2e ⁻ → H ₂ O
[0003]
As the hydrogen ion source, there are known a method in which hydrogen gas is directly supplied and a method in which alcohols such as methanol and other liquid hydrogen compounds are reacted with water, and methanol is supplied to the anode 72. The fuel cell to be used is called a direct methanol fuel cell (DMFC) and can be miniaturized and sealed, so that it is expected to be used for portable terminals.
[0004]
Known polymer electrolyte membranes 71 include those made of an ion conductive resin such as a perfluorosulfonic acid polymer, and those obtained by impregnating an expanded porous polytetrafluoroethylene membrane with an ion conductive resin. Catalyst layers 76 and 77 mainly composed of carbon powder carrying a noble metal catalyst such as platinum are disposed in close contact with both surfaces of the polymer electrolyte membrane 71, and both the gas permeability and the conductivity are provided outside the catalyst layer 76. The gas diffusion layers 74 and 75 are disposed in close contact with each other. The polymer electrolyte membrane 71 and the catalyst layers 76 and 77 are mechanically integrated, or the polymer electrolyte membrane 71, the catalyst layers 76 and 77, and the gas diffusion layers 74 and 75 are mechanically integrated. It is called MEA (Membrane-Electrode Assembly) and has come to be used as a component of fuel cells.
[0005]
As shown in the side sectional view of FIG. 18 and the external view of FIG. 19, the conventionally proposed fuel cell has gas diffusion on both sides of the MEA (a catalyst layer formed on both sides of the polymer electrolyte membrane) 81. Layers 82 and 83 are provided, and these are sandwiched between separators (housings) 84 and 85. 86 is a cathode side gas flow path, 87 is an anode side gas flow path, 88 is a cathode gas (hydrogen) introduction pipe, 89 is an anode gas (oxygen or air) introduction pipe, and 90 is a generated water discharge. It is a tube.
[0006]
In the fuel cell having such a configuration, a gas such as hydrogen or a liquid such as methanol serving as fuel is switched between supply and cutoff by opening / closing a bubble provided in the middle of the introduction pipe ( For example, Patent Document 1).
[0007]
[Patent Document 1]
Japanese Patent Laid-Open No. 08-0778037
[Problems to be solved by the invention]
In the fuel cell having such a configuration, a gas such as hydrogen or a liquid such as methanol used as fuel is switched between supply and cutoff by opening and closing a valve provided in the middle of the introduction pipe. However, with this method, the capacity of the space between the valve and the polymer electrolyte membrane surface is large, where fuel gas or liquid loss occurs and the efficiency decreases, and the fuel cell is turned on, There is a problem such as a time delay of the off operation. In addition, DMFC is expected to be used as a power generator for portable terminals, but methanol that has accumulated between the valve and the surface of the polymer electrolyte membrane diffuses through the polymer electrolyte membrane and becomes an oxygen electrode (cathode). ) And reacts directly with oxygen in the air, causing abnormal heat generation. Furthermore, there is a problem in that it is difficult to secure a space for mounting a valve, because miniaturization is required for use in a portable terminal.
[0009]
The present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to suppress the occurrence of loss when switching between supply and shutoff of fuel gas or liquid, and a fuel cell. An object of the present invention is to provide a fuel cell that can suppress the occurrence of a time delay in the on / off operation of the battery. Furthermore, another object of the present invention is to provide a fuel cell that can prevent abnormal heat generation due to the reaction between methanol and oxygen and can be miniaturized.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a solid polymer electrolyte membrane, a catalyst layer disposed across the solid polymer electrolyte membrane, a gas diffusion layer disposed outside the catalyst layer, and the gas A separator disposed on the outside of the diffusion layer, and the separator is provided with a gas flow path including a plurality of grooves on the polymer electrolyte membrane side, the gas diffusion of the separator On the layer side, a planar blocking device having a plurality of holes paired with the grooves of the gas flow path is provided so as to be substantially parallel to the solid polymer electrolyte membrane. Provided is a fuel cell characterized in that it can be disconnected from the gas diffusion layer by moving in a direction along the gas diffusion layer .
[0011]
According to the fuel battery cell of the present invention, since the planar shut-off device that shuts off the supply of gas or liquid containing fuel or oxygen is provided in the vicinity of the anode surface or the cathode surface, the space where the fuel stays is provided. The capacity can be made extremely small, the occurrence of fuel loss can be suppressed, and the occurrence of a time delay in the on / off operation of the fuel cell can be suppressed. And, when a planar blocking device is provided on the cathode side, it is prevented that methanol diffuses through the polymer electrolyte membrane and escapes to the cathode side and directly reacts with oxygen in the air, eliminating the cause of abnormal heat generation. Will come to be. Further, since a space for mounting the valve is not required, the fuel cell can be reduced in size. In order to achieve the object of the present invention, it is also possible to provide a planar blocking device at both a position close to the anode surface and a position close to the cathode surface.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is an explanatory side sectional view of an embodiment of a fuel cell according to the present invention. An anode gas diffusion layer 2 is provided on one side of an MEA 1 having a catalyst layer adhered to both sides of a polymer electrolyte membrane, and the other side. Is provided with a cathode gas diffusion layer 3, and these gas diffusion layers 2 and 3 are sandwiched by separators (housings) 4 and 5 from the outside. Hydrogen gas is introduced from the gas passage 6 and oxygen gas is introduced from the gas passage 7. It becomes the composition which is done. A spacer 10 having a gas flow path 11 is provided between the separator 4 having a gas flow path 6 for feeding hydrogen gas and the anode gas diffusion layer 2, and a shutter (planar blocking) is provided between the separator 4 and the spacer 10. Device) 8 is provided. A hole 9 is formed in the shutter 8, and the gas flow paths 6 and 11 communicate with each other through the hole 9. FIG. 1 shows a state in which a fuel cell is in operation. Hydrogen gas introduced from a gas introduction pipe (not shown) passes through a gas flow path 6, a hole 9 and a gas flow path 11. The reaction proceeds to MEA1 and proceeds. In FIG. 1, 12 is a gasket for maintaining airtightness.
[0013]
When stopping the operation of the fuel cell, if the shutter 8 is moved in the direction of the arrow in FIG. 1, the hole 9 is sandwiched between the separator 4 and the spacer 10 as shown in FIG. The supply of hydrogen gas is interrupted by the shutter 8. As is apparent from FIG. 2, the space existing between the MEA 1 and the shutter 8 is extremely small, so that the amount of hydrogen gas remaining in this space can be minimized, fuel efficiency can be improved, and The time delay of the on / off operation can be reduced. Furthermore, in the present embodiment, since the spacer 10 is interposed between the anode gas diffusion layer 2 and the shutter 8, wear of the anode gas diffusion layer 2 due to opening / closing of the shutter 8 can be prevented.
[0014]
FIG. 3 shows another embodiment of the fuel battery cell of the present invention. The difference from the embodiment of FIG. 1 is that the anode gas diffusion layer 2 and the separator 4 are not provided without the spacer 10. A shutter 8 is disposed between them. Almost no space exists between the MEA 1 and the shutter 8, and the influence of hydrogen gas can be more effectively suppressed.
[0015]
FIG. 4 shows still another embodiment of the fuel cell according to the present invention, in which a shutter 8 is disposed between the cathode gas diffusion layer 3 and the separator 5. Shown is a state in which the fuel cell is in operation, and oxygen gas is supplied to the cathode gas diffusion layer 3 through the holes 9. When stopping the operation of the fuel cell, the supply of oxygen is blocked by moving the shutter 8 in the direction of the arrow in FIG. 4 and closing the hole 9 with the separator 5. In this case, since the hydrogen gas or methanol staying in the gas flow path 6 and the like is blocked by the shutter 8 from the anode side, the reaction with the oxygen gas is suppressed and abnormal heat generation is prevented.
[0016]
5 and 6 show a reference example of the fuel battery cell of the present invention. The form of this reference example uses the separator 4 as a planar interrupting device so that the supply of hydrogen gas can be interrupted. FIG. 5 shows a state where the fuel cell is in operation, and hydrogen gas is supplied to the anode gas diffusion layer 2 side through the gas flow path 6 formed in the separator 4 and the gas flow path 11 formed in the spacer 10. It has come to be. When the separator 4 is moved in the direction of the arrow in the figure to a state as shown in FIG. 6, the supply of hydrogen gas is cut off and the fuel cell is stopped. In this manner, by making the separator 4 also serve as a planar blocking device, a thinner fuel cell can be realized.
[0017]
7 and 8 show a reference example of the fuel cell of the present invention, and FIG. 8 is a cross-sectional view taken along the line AA ′ of FIG. The form of the present reference example is an example of a flat plate type integrated fuel battery cell, and a lid 12 is provided on the open electrode side. By closing the lid 12, the supply of gas containing fuel or oxygen is shut off, The operation of the fuel cell can be stopped. In the figure, reference numeral 13 denotes a fuel cell, and in the form of this reference example , nine fuel cells 13 are arranged on one plane, and these are electrically connected in series. Further, 1 is an MEA, 2 and 3 are gas diffusion layers, 14 is a housing, 15 is a fuel flow path, and 16 is a fuel tank.
[0018]
9 and 10 show a reference example of the fuel battery cell of the present invention, and FIG. 10 is a cross-sectional view taken along the line BB ′ of FIG. The form of this reference example is also an example of a flat plate type integrated fuel battery cell like the reference examples of FIG. 7 and FIG. 8, and a shutter 17 is provided on the integrated gas electrode side. The supply of the gas containing oxygen is shut off, and the operation of the fuel cell can be stopped. In the figure, 13 is a fuel cell, 1 is MEA, 2 and 3 are gas diffusion layers, 18 is a housing, 15 is a fuel flow path, and 16 is a fuel tank.
[0019]
11 and 12 show a reference example of the fuel cell of the present invention, and FIG. 12 is a cross-sectional view taken along the line CC ′ of FIG. The form of this reference example is an example of a cylindrical fuel cell, and a laminate composed of MEA 1 and gas diffusion layers 2 and 3 is wound around the outer periphery of the separator 19 in a cylindrical shape, and a wire 17 is provided around the periphery. The flange 18 is provided at both ends. A shutter 20 is provided on the inner periphery of the separator 19. By rotating the shutter 20, a gas containing fuel or oxygen is supplied from the fuel flow path 21, and the supply is shut off. It has become. As shown in FIG. 13, the separator 19 has a plurality of vertical grooves 22, and a plurality of holes 23 are formed in the vertical grooves 22. As shown in FIG. 14, the shutter 20 has a plurality of holes 24. When the positions of the holes 23 and 24 coincide with each other, a gas containing fuel or oxygen is supplied, and the battery enters an operating state. By shifting the positions of the holes 23 and the holes 24, the supply of the gas containing fuel or oxygen is cut off, and the operation of the battery is stopped. FIG. 15 shows another reference example embodiment of the separator, the separator 25 has a plurality of transverse grooves 26, and hole 27 is provided with a plurality of the transverse grooves 26.
[0020]
FIG. 16 shows still another reference example of the fuel battery cell of the present invention. In this reference embodiment, the fuel cells 28 having the structure described in the embodiment of FIGS. 1 to 4 are stacked in multiple layers, and the shutters 29 provided in each fuel cell 28 are connected by a connecting plate 30. It is composed. With such a configuration, the supply of the fuel or oxygen-containing gas to the fuel cell 28 can be shut off at the same time, and the operation of the battery can be stopped. In the figure, 31 is a fuel gas introduction pipe, 32 is a fuel gas discharge pipe, 33 is an air introduction pipe, and 34 is an air discharge pipe.
[0021]
【The invention's effect】
As described above, the fuel battery cell of the present invention is provided with the planar shut-off device that shuts off the supply of fuel or oxygen-containing gas in the vicinity of the anode surface or the cathode surface, so that the fuel stays. The capacity of the space can be made extremely small, the occurrence of fuel loss can be suppressed, and the occurrence of a time delay in the on / off operation of the fuel cell can be suppressed. And, when a planar blocking device is provided on the cathode side, it is prevented that methanol diffuses through the polymer electrolyte membrane and escapes to the cathode side and directly reacts with oxygen in the air, eliminating the cause of abnormal heat generation. Will come to be. Furthermore, since the fuel battery cell of the present invention does not require a space for mounting a valve, the fuel battery cell can be downsized.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of an embodiment of a fuel battery cell of the present invention (in operation state).
FIG. 2 is an explanatory diagram of an embodiment of a fuel cell of the present invention (state of operation stop).
FIG. 3 is an explanatory diagram of another embodiment of the fuel battery cell of the present invention.
FIG. 4 is an explanatory diagram of another embodiment of the fuel cell according to the present invention.
FIG. 5 is an explanatory diagram of a reference example of a fuel battery cell according to the present invention (state during operation).
FIG. 6 is an explanatory diagram of a reference example of a fuel battery cell according to the present invention (operation stopped state).
FIG. 7 is an explanatory diagram of a reference example of a fuel cell of the present invention (embodiment of a flat plate type integrated fuel cell).
FIG. 8 is a cross-sectional explanatory view taken along the line AA ′ of FIG.
FIG. 9 is an explanatory diagram of a reference example of a fuel cell of the present invention (embodiment of a flat plate type integrated fuel cell).
10 is a cross-sectional explanatory view taken along the line BB ′ of FIG. 9;
FIG. 11 is an explanatory diagram of a reference example of a fuel cell according to the present invention (embodiment of a cylindrical fuel cell).
12 is a cross-sectional explanatory view taken along the line CC ′ in FIG. 11;
FIG. 13 is a perspective explanatory view of a reference example of a separator.
FIG. 14 is an explanatory perspective view of a reference example of a shutter.
FIG. 15 is a perspective explanatory view of a reference example of a separator.
FIG. 16 is an explanatory diagram of a reference example in which fuel cells are stacked in multiple layers.
FIG. 17 is a diagram illustrating the principle of a fuel cell.
FIG. 18 is a cross-sectional explanatory view of a conventional fuel cell.
FIG. 19 is an external explanatory view of a conventional fuel cell.
[Explanation of symbols]
1: MEA
2, 3: Gas diffusion layer 4, 5: Separator 6, 7: Gas flow path 8: Shutter 9: Hole 10: Spacer 11: Gas flow path 12: Gasket

Claims (3)

A solid polymer electrolyte membrane;
A catalyst layer disposed across the solid polymer electrolyte membrane;
A gas diffusion layer disposed outside the catalyst layer;
A separator disposed outside the gas diffusion layer,
The separator is a fuel cell in which a gas flow path including a plurality of grooves is provided on the polymer electrolyte membrane side,
On the gas diffusion layer side of the separator, a planar blocking device having a plurality of holes paired with the grooves of the gas flow path is provided so as to be substantially parallel to the solid polymer electrolyte membrane, A fuel battery cell characterized in that a gas barrier layer can be blocked by moving a planar blocking device in a direction along the gas diffusion layer. 2. The fuel cell according to claim 1, wherein a spacer having a plurality of holes paired with a groove of the gas flow path is provided between the gas diffusion layer and the planar blocking device. The planar shut-off device has a stopper for locking the planar shut-off device to the separator so that the planar shut-off device cannot move from a gas channel groove in which the plurality of holes are paired to an adjacent gas channel groove. The fuel cell according to claim 1.

Images