JPH09120833A - Solid high polymer electrolyte fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell in which reaction gas can be introduced at a gas introducing part of a fuel cell lamination body without generating water drops to achieve stable operation for a long period. SOLUTION: A fuel cell lamination body comprises plural cells 6 laminated with each other, collector plates 7A, 7B and insulation plates 8A, 8B disposed on both ends of them, and tightening plates 9A, 9B disposed on both end surfaces of them, and tightening devices 12 to pressurize and support them at specified pressure. In this case, gas introducing tubes 10A, 10B, and gas discharge tubes 17A, 17B are respectively installed on upper end surfaces and lower end surfaces of the insulation plates 8A, 8B, so fuel gas and oxidier gas are distributed to the respective cells 6, thereby generation of water drops by cooling at an introducing part can be avoided.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a structure of a fuel cell body of a solid polymer electrolyte fuel cell.

[0002]

2. Description of the Related Art FIG. 3 is a cross-sectional view schematically showing a structural example of a single cell of a solid polymer electrolyte fuel cell which has been conventionally used. In the unit cell 6 shown in FIG. 3, the fuel cell 1 has a fuel electrode 1B and an oxidizer electrode 1 on both main surfaces of an electrolyte layer 1A made of a thin rectangular solid polymer electrolyte membrane.
It is configured by closely stacking C. The fuel electrode 1B and the oxidant electrode 1C both support a catalyst layer containing a catalytically active substance, supply and discharge a fuel gas or an oxidant gas, and further serve as a current collecting member. It is composed of an electrode base material, and the catalyst layer is disposed in close contact with both main surfaces of the electrolyte layer 1A by hot pressing. The separator 2A disposed facing the fuel electrode 1B side of the fuel cell 1 is made of a gas impermeable material,
It is provided with a plurality of recessed fuel gas passage grooves 3A for allowing the fuel gas to flow therethrough facing the surface of the fuel electrode 1B, and a convex protrusion between the fuel gas passage grooves 3A. The tip surface of the is closely contacted with the surface of the fuel electrode 1B. Similarly, the separator 2B arranged facing the oxidant electrode 1C is also made of a gas impermeable material, and has a plurality of oxidant gas passages that allow the oxidant gas to flow therethrough facing the surface of the oxidant electrode 1C. The flow grooves 3B are provided, and the tip surfaces of the convex projections between the oxidant gas flow grooves 3B are in close contact with the surface of the oxidant electrode 1C. Further, the gas seal body 5 has a role of preventing the fuel gas flowing through the fuel gas flow groove 3A and the oxidant gas flowing through the oxidant gas flow groove 3B from leaking out of the respective flow paths. This is achieved, and the separators 2A, 2B and the fuel cell 1 are arranged in the voids in the peripheral edge portions.

The voltage generated by one fuel cell 1 is 1
Since it is a low value of about [V] or less, a plurality of unit cells 6 having the structure as shown in FIG. 3 are connected in series to each other to form a fuel cell stack, and the generated voltage is increased for practical use. Is common. FIG. 4 is a perspective view schematically showing a typical conventional example of a fuel cell stack of a solid polymer electrolyte fuel cell.

As shown in the figure, in the fuel cell stack of this configuration example, a plurality of unit cells 6 are sequentially stacked, and a current collector plate for extracting DC power generated by the plurality of unit cells 6 at both ends thereof. 7A, 7B and insulating plates 13A, 13B for electrically insulating from the structure are arranged, and further, tightening plates 14A, 14B are arranged at both ends thereof, and a proper pressing force is applied by the tightening tool 12. It is configured by adding and tightening. Gas inlets 15A, 15B for introducing the fuel gas and the oxidant gas are provided on the upper side of the side end surfaces of the tightening plates 14A, 14B arranged at both ends
However, there is also a gas outlet 1 for discharging these gases at the bottom.
6A and 16B are provided. Gas inlet 15A, 1
The gas introduced from 5B is sent to the stacked unit cells 6 and flows through the gas flow grooves inside the unit cells 6 toward the lower side, that is, in the direction of gravity to generate an electrochemical reaction to generate power, It is sent to the discharge ports 16A and 16B and discharged to the outside.

FIG. 5 is a cross-sectional view of an essential part schematically showing the structure of the gas introducing portion of the conventional fuel cell stack shown in FIG. The current collector plate 7A, the insulating plate 13A, and the tightening plate 14A arranged at the ends of the plurality of stacked unit cells 6 are formed with communication holes that communicate with the gas introduction port 15A and are guided in the horizontal direction. The introduced gas is sent to each cell 6 through this communication hole. Current collecting plate 7A, insulating plate 13A, tightening plate 1
As shown in the figure, a sealing material 11 is disposed on the outer peripheral portion of the communication hole on the laminated surface of 4A to prevent the gas flowing through the communication hole from leaking to the outside. In this figure, the portion communicating with the gas inlet 15A in FIG. 4 is shown, but the gas inlet 1
5B and the portions communicating with the gas outlets 16A and 16B are also formed with communicating holes. As described above, the fuel gas and the oxidant gas are introduced in the horizontal direction, and each unit cell is connected. It flows in the direction of gravity from the upper part of 6 to the lower part, is guided in the horizontal direction, and is discharged.

[0006]

In the solid polymer electrolyte fuel cell, it is desirable that the temperature is high in order to enhance the power generation efficiency by the electrochemical reaction, and each cell 6 is kept at a high temperature and kept at a predetermined temperature. A method of supplying heated gas is generally adopted. Also in the fuel cell stack having the configuration shown in FIG. 4, a predetermined DC power can be obtained by effectively utilizing the heat generated by power generation to maintain each cell 6 at a high temperature and supplying the heating gas. Becomes

In the fuel cell stack having the structure shown in FIG. 4, each of the unit cells 6 serving as a heat source, the current collector plates 7A and 7B, and the insulating plates 13A and 13B having poor thermal conductivity are external only at their end faces. Because of the exposed structure, these components are relatively easily held at high temperatures. On the other hand, tightening plates 14A and 14B at both ends for fastening them
Since one of the side surfaces is exposed to the outside, it is efficiently cooled by the outside air and is maintained at a temperature significantly lower than those of other components.

However, in the configuration of FIG. 4, gas inlets 15A and 15B for introducing the fuel gas and the oxidant gas and gas outlets for exhausting these gases are formed on the side end faces of the fastening plates 14A and 14B. Since 16A and 16B are provided, the gas heated and supplied to the gas inlets 15A and 15B is cooled by the tightening plates 14A and 14B that are kept at a low temperature, and the contained vapor is condensed. The chances of water droplets increasing. When water droplets are generated, they may flow into the unit cell 6 together with the gas, fill the gas flow groove to block the flow of gas, and cause a situation in which the power generation efficiency of the unit cell 6 is significantly reduced.

An object of the present invention is to provide a solid polymer electrolyte fuel in which the reaction gas is introduced in the gas introduction portion of the fuel cell stack without generating water droplets and can be stably operated for a long period of time without lowering power generation efficiency. To provide batteries.

[0010]

In order to achieve the above object, in the present invention, a fuel electrode and an oxidizer electrode are adhered to two main surfaces of an electrolyte layer made of a solid polymer electrolyte membrane, respectively. A plurality of fuel cells, a separator having a plurality of fuel gas passage grooves arranged on the side surface of the fuel cell on the fuel electrode side, and a plurality of separators arranged on the side surface of the fuel cell on the oxidant electrode side. A plurality of unit cells comprising a separator having a groove for flowing an oxidant gas are stacked in series, and an insulating plate for electrical insulation is interposed at both ends thereof to dispose a tightening plate and hold under pressure. In a solid polymer electrolyte fuel cell in which fuel gas is supplied to the fuel electrode and oxidant gas is supplied to the oxidant electrode to obtain DC power, the insulating plate may be formed of, for example, polycarbonate, fluororesin, fiber reinforced plastic, or the like. Excellent electrical insulation The end face of the insulating plate, which is formed of a good electrically insulating material having low thermal conductivity and is located in the direction orthogonal to the stacking direction of the fuel cell stack, has a gas inlet and a gas outlet for fuel gas and oxidant gas. At least the gas inlet will be provided.

As described above, at least one of the gas introduction port and the gas discharge port of the fuel gas and the oxidant gas is provided on the end face of the insulating plate formed of the good electrically insulating material having the excellent electric insulating property and the low thermal conductivity. If you have an inlet,
Unlike the tightening plate, the insulating plate is kept at a high temperature, so that the supplied fuel gas and oxidant gas are not cooled to cause water droplets, and therefore water droplets enter the cell and the characteristics deteriorate. Does not occur.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic perspective view of a fuel cell stack showing an embodiment of a solid polymer electrolyte fuel cell of the present invention. The structure of the fuel cell stack of this figure and FIG.
The difference from the conventional example shown in FIG. 3 is that the insulating plates 8A and 8B arranged at both ends of the stacked unit cells 6 and the tightening plate 9 are provided.
It is in the configuration of A and 9B. That is, in the conventional example shown in FIG. 4, the fuel gas and the oxidant gas were introduced and discharged through the gas inlets 15A and 15B and the gas outlets 16A and 16B provided on the side surfaces of the tightening plates 14A and 14B. On the other hand, in the fuel cell stack of FIG. 1, the tightening plates 9A and 9B are made of polycarbonate, which is a material having no gas introduction / exhaust ports, excellent electrical insulation, and poor thermal conductivity. The insulating plates 8A and 8B are characterized in that gas introducing pipes 10A and 10B are provided on the upper end faces thereof, and gas discharge pipes 17A and 17B are provided on the lower end faces thereof, respectively.

FIG. 2 is a cross-sectional view of an essential part showing the structure of the gas introduction portion of the fuel cell stack of FIG. Although this figure shows the configuration of the gas introduction portion connected to the gas introduction pipe 10A, the gas introduction portion connected to the gas introduction pipe 10B and the gas discharge portion connected to the gas discharge pipes 17A and 17B are also similarly configured. There is. In the gas introducing portion connected to the gas introducing pipe 10A shown in FIG. 2, the gas introducing pipe 10A is connected to the upper end surface of the insulating plate 8A, and the reaction gas introduced from the gas introducing pipe 10A is It is guided in the horizontal direction through the gas flow holes inside and is sent to each of the stacked unit cells 6 through the flow holes provided in the current collector 7A. A sealing material 11 is provided on the connection surface of the gas introduction pipe 10A with the insulating plate 8A, the connection surface of the insulating plate 8A with the current collector plate 7A, and the connection surface between the current collector plate 7A and the unit cell 6. The leakage of the introduced reaction gas is prevented.

In this structure, since the reaction gas is introduced through the insulating plate 8A having a high temperature and does not pass through the tightening plate 9A having a low temperature, there is no possibility that the reaction gas is cooled in the introducing portion to generate water droplets. Therefore, there is no risk of water droplets flowing into the unit cell 6 and deteriorating the characteristics. Although the insulating plates 8A and 8B are made of polycarbonate in the above configuration example, the insulating plates 8A and 8B are not limited to polycarbonate, and are excellent in electrical insulation of fluororesin, fiber reinforced plastic, etc. and have low thermal conductivity and good electrical insulation. The same effect can be obtained even if the material is made of a material.

[0015]

As described above, according to the present invention, a fuel battery cell in which a fuel electrode and an oxidant electrode are closely attached to two main surfaces of an electrolyte layer composed of a solid polymer electrolyte membrane, respectively. A separator having a plurality of fuel gas passage grooves arranged on the fuel electrode side surface of the fuel cell, and a plurality of oxidant gas passage grooves arranged on the oxidant electrode side surface of the fuel cell. A plurality of unit cells each having a separator having are stacked in series, and clamping plates are arranged at both ends thereof with an insulating plate for electrical insulation interposed therebetween to pressurize and hold, and fuel gas to a fuel electrode, Further, in a solid polymer electrolyte fuel cell in which an oxidant gas is supplied to an oxidant electrode to obtain direct current power, an insulating plate is made of, for example, polycarbonate, fluororesin, fiber reinforced plastic, or the like having excellent electrical insulation and thermal conductivity. Lower than electrical insulating material In addition, since the end face of the insulating plate located in the direction orthogonal to the stacking direction of the fuel cell stack is provided with at least the gas inlet port of the fuel gas and the oxidant gas and the gas outlet port, The reaction gas is introduced in the gas introduction part of the fuel cell stack without generating water droplets, and a solid polymer electrolyte fuel cell that can be stably operated for a long period without lowering power generation efficiency can be obtained. Became.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a fuel cell stack showing an embodiment of a solid polymer electrolyte fuel cell of the present invention.

FIG. 2 is a cross-sectional view of an essential part showing the configuration of a gas introduction portion of the fuel cell stack of FIG.

FIG. 3 is a cross-sectional view schematically showing a configuration example of a unit cell of a solid polymer electrolyte fuel cell which has been conventionally used.

FIG. 4 is a perspective view schematically showing a typical conventional example of a fuel cell stack of a solid polymer electrolyte fuel cell.

5 is a cross-sectional view of an essential part showing the configuration of a gas introduction part of the conventional fuel cell stack of FIG.

[Explanation of symbols]

 1 Fuel Battery Cell 1A Electrolyte Layer 1B Fuel Electrode 1C Oxidizer Electrode 2A, 2B Separator 6 Single Cell 7A, 7B Current Collector 8A, 8B Insulation 9A, 9B Clamping Plate 10A, 10B Gas Inlet Pipe 11 Sealant 12 Tightening Tool 13A, 13B Insulation plate 14A, 14B Tightening plate 15A, 15B Gas inlet 16A, 16B Gas outlet 17A, 17B Gas outlet pipe

Claims (2)

[Claims] 1. A fuel battery cell in which a fuel electrode and an oxidizer electrode are closely attached to two main surfaces of an electrolyte layer made of a solid polymer electrolyte membrane, and a side surface of the fuel battery cell on the fuel electrode side. A plurality of unit cells each having a separator having a plurality of fuel gas flow grooves arranged in the fuel cell and a separator having a plurality of oxidant gas flow grooves arranged on the side surface of the fuel cell on the oxidant electrode side. They are stacked in series and a clamping plate is placed with an insulating plate for electrical insulation interposed at both ends to maintain pressure and supply fuel gas to the fuel electrode and oxidant gas to the oxidizer electrode. In the solid polymer electrolyte fuel cell for obtaining DC power, the insulating plate is formed of a good electrically insulating material having excellent electrical insulation and low thermal conductivity, and the stacking direction of the fuel cell stack is At the end face of the insulating plate located in the orthogonal direction, the fuel gas And a solid polymer electrolyte fuel cell, comprising at least a gas introduction port of a gas introduction port and a gas discharge port of an oxidant gas. 2. The solid polymer electrolyte according to claim 1, wherein the good electrically insulating material forming the insulating plate is any one of polycarbonate, fluororesin and fiber reinforced plastic. Type fuel cell.