JPH10308229A - Solid high polymer electrolyte type fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stable battery characteristic by holding single batteries located at both ends of a fuel cell layered product the same in temperature as single batteries located at the center side. SOLUTION: A fuel cell layered product comprising by layering a plurality of single batteries and arranging collector plates, electrical insulating plates, and tightening plates at its both ends controls a temperature drop of the single batteries at the both ends by providing a cooling water passage consisting of a plurality of flow grooves 22 separated with a partition 21 at the side of an electrical insulating plate 11A, guiding a cooling water that cools the single battery and is discharged to an inlet opening 19 located on bottom to be circulated in the cooling water passage, and discharging from a cooling water discharge passage 18A located on top.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid polymer electrolyte fuel cell which uses a solid polymer electrolyte membrane as an electrolyte layer, supplies fuel gas and oxidizing gas, and obtains electric energy by an electrochemical reaction.

[0002]

2. Description of the Related Art A fuel cell includes a solid polymer electrolyte type, a phosphoric acid type, a molten carbonate type, a solid oxide electrolyte type, and the like, depending on the type of electrolyte used. This fuel cell utilizes the fact that when a polymer resin membrane having a proton (hydrogen ion) exchange group therein is saturated with water, it exhibits low resistivity and functions as a proton conductive electrolyte.

FIG. 3 is an exploded sectional view schematically showing a configuration of a unit cell of a conventional solid polymer electrolyte fuel cell.
In the figure, a membrane electrode assembly 1 is composed of an electrolyte layer 1A made of a thin rectangular plate-shaped solid polymer electrolyte membrane, and a fuel electrode layer 1B and an oxidant electrode layer 1C joined thereto. Each of the fuel electrode layer 1B receiving the supply of the fuel gas and the oxidant electrode layer 1C receiving the supply of the oxidant gas supports the catalyst layer containing the catalyst active material and supports the catalyst layer, and transmits the fuel gas or the oxidant gas. A porous electrode substrate having a function of supplying and discharging to and from the catalyst layer and having a function as a current collector. The catalyst layer is brought into close contact with both main surfaces of the membrane electrode assembly 1 by hot pressing. Are joined.

The separator 2A is made of a gas-impermeable material, and has a plurality of gas flow grooves 3A separated on one side by a partition 4A and separated by a partition 7A on the other side. A plurality of cooling water circulation grooves 6A are provided. Similarly, the separator 2B is also manufactured using a gas-impermeable material, and a plurality of gas distribution grooves 3B separated on one side by a partition 4B, and separated by a partition 7B on the other side. A plurality of cooling water circulation grooves 6B are provided. In the unit cell, the side surface of the separator 2A provided with the gas circulation groove 3A is connected to the fuel electrode layer 1
B, the side surface of the separator 2B provided with the gas circulation groove 3B is placed on the oxidant electrode layer 1 of the membrane electrode assembly 1.
The gas sealing material 5 keeps the periphery airtight, and the cooling water sealing material 8 prevents the cooling water from leaking to the periphery. . In this configuration, the fuel gas flows through the gas flow groove 3A, and the oxidant gas flows through the gas flow groove 3B, whereby an electrochemical reaction occurs in the membrane electrode assembly 1 and the two separators 2A, 2B During this time, electric energy is obtained. Further, by causing the cooling water to flow through the cooling water circulation grooves 6A and 6B, heat generated due to the electrochemical reaction is removed, and the temperature is kept constant.

[0005] The voltage generated by one cell is 1 [V].
Since the value is as low as about or less, it is common to form a fuel cell stack by connecting a plurality of cells having the above-described configuration in series, and to increase the generated voltage for practical use. Further, in order to keep the specific resistance of the solid polymer electrolyte membrane small and to maintain the power generation efficiency high, it is usually used at an operating temperature of 50 ° C to 100 ° C.

FIG. 4 is a side view schematically showing the structure of a fuel cell stack of a conventional solid polymer electrolyte fuel cell. In the fuel cell stack of this configuration, a plurality of unit cells 9 are stacked, and a current collecting plate 10 for taking out DC power generated by the unit cells 9 is disposed at both ends thereof. A tightening plate 12 is provided with an electric insulating plate 11 for electrically insulating the battery 9 and the current collecting plate 10 from the structure, a tightening bolt 13, a tightening disc spring 14, and a tightening tool. A suitable pressing force is applied by tightening between the tightening plates 12 on both side ends by 15. In a solid polymer electrolyte fuel cell, the membrane electrode assembly exhibits ionic conductivity for the first time by maintaining it in a water-containing state.
The fuel gas and the oxidizing gas are supplied to the membrane electrode assembly after being humidified and containing a certain amount of moisture. Therefore, in order to prevent the water contained in the fuel gas or the oxidizing gas from dew condensation and blocking the flow path, the separator 9 shown in FIG.
Fuel gas and oxidizing gas flowing through the gas flow grooves 3A and 3B of A and 2B are arranged so as to flow from the upper side to the lower side in the direction of gravity.

FIG. 5 is a schematic diagram showing a configuration example of a cooling water flow path of a fuel cell stack of a conventional solid polymer electrolyte fuel cell. The cooling water is supplied from a cooling water supply port (not shown) provided above the end surface of the clamping plate 12 at both ends, and after flowing through communication holes provided in the electric insulating plate 11 and the current collecting plate 10, The separators 2A and 2B of the plurality of unit cells 9 stacked are guided to the upper ends in the direction of gravity, flow through the cooling water circulation grooves 6A and 6B downward in the direction of gravity, and collect the current collector plate 10 and the electrical insulating plate 11. After passing through the communication holes provided in the clamping plate 12, the cooling water is discharged to the outside from a cooling water discharge port provided in a lower portion of the end face of the fastening plate 12.

FIG. 6 is a perspective view showing the structure of an electric insulating plate 11 used in a fuel cell stack of a conventional solid polymer electrolyte fuel cell. As shown in the figure, the gas flow path 16 on the electric insulating plate 11 is configured such that the supply side of the fuel gas and the oxidizing gas is arranged at the upper part in the direction of gravity, and the discharge side is arranged at the lower part in the direction of gravity. In addition, blockage of the flow path due to dew condensation of moisture in the gas is prevented. Also, the cooling water supply passage 1
7 is arranged at the upper part in the direction of gravity, and the cooling water drainage channel 18 is arranged at the lower part in the direction of gravity.

[0009]

In the solid polymer electrolyte fuel cell constructed as described above, as described above, the fuel gas and the oxidizing gas are humidified to contain a certain amount of water, and then the membrane electrode is joined. It is supplied to the body. Also,
In order to reduce the specific resistance of the solid polymer electrolyte membrane to maintain high power generation efficiency, and to prevent dew condensation due to the temperature decrease of the humidified fuel gas and oxidizing gas as described above, the gas flow paths of these gases The cooling water flowing through the separator provided with is controlled to remove heat generated in each unit cell due to the power generation reaction, and to maintain the temperature of each unit cell at a uniform temperature of 50 ° C to 100 ° C. Have been.

However, in a fuel cell stack having the above-described configuration in which a plurality of cells are stacked and a current collecting plate, an electric insulating plate, and a clamping plate are disposed at both ends thereof, the unit cells located at both ends are arranged. Since the battery is held in a state where one end face is in contact with the current collector plate, the rate of heat dissipation from the side surface is larger than that of the unit cells provided with unit cells on both sides and stacked. Therefore, the temperature of the unit cells located at both ends of the stacked unit cells tends to be lower than the temperature of the unit cells located at the center. As a result, the unit cells located at both ends of the stacked unit cells have a reduced cell characteristic due to an increase in the specific resistance of the solid polymer electrolyte membrane, and humidified fuel gas and oxidizing gas are condensed, Since the gas flow passage is likely to be closed, gas diffusion of the fuel gas and the oxidizing gas is hindered, and there is a problem that the battery characteristics are deteriorated.

An object of the present invention is to maintain the temperature of a unit cell located at both ends of a fuel cell stack formed by stacking a plurality of unit cells substantially equal to the temperature of another unit cell located at the center. An object of the present invention is to provide a solid polymer electrolyte fuel cell that can operate stably and efficiently without causing a decrease in cell characteristics due to a decrease in temperature.

[0012]

In order to achieve the above object, in the present invention, a membrane electrode assembly is formed by adhering electrode layers to both main surfaces of an electrolyte layer comprising a solid polymer electrolyte membrane. And further, a separator having a gas circulation groove and a cooling water circulation groove on both outer surfaces thereof is arranged to form a unit cell, and a plurality of cells are stacked with the stacking direction arranged in a horizontal direction, and at both ends thereof, A current collecting plate for taking out the generated DC electricity and an electric insulating plate for maintaining electrical insulation are sequentially arranged, then tightened by a tightening plate and held under pressure, and cooling water is supplied to the cooling water circulation groove. The membrane electrode assembly is maintained at a preferable temperature by flowing the fuel gas and the oxidizing gas through the gas flow grooves to supply the membrane electrode assembly with the electrode layer to take out the DC electricity generated from the current collector plate. In a solid polymer electrolyte fuel cell, (1) The electric insulating plate is provided with a cooling water passage through which cooling water for controlling the temperature of the unit cells located at both terminals flows, for example, a cooling water passage comprising a plurality of concave grooves formed on the side surface of the electric insulating plate for cooling. We let water flow.

(2) The cooling water discharged through the cooling water flow grooves of the separator is used as the cooling water flowing through the cooling water flow path provided on the electric insulating plate. In the fuel cell stack of the conventional configuration, the temperature of the unit cells located at both ends has decreased due to heat dissipation through the current collector plate, the electric insulating plate and the clamp plate located at both ends of the stack. . On the other hand, as described in the above (1), if the electric insulating plate is provided with a cooling water flow path and the temperature of the cells located at both terminals is maintained at the reference temperature by the main cooling water, the conventional cooling water flow can be obtained. The deterioration of the battery characteristics due to the temperature drop of the unit cell of the terminal is avoided. Further, if this cooling water flow path is, for example, a cooling water flow path composed of a plurality of concave grooves formed on the side surface of the electric insulating plate, heat exchange is effectively performed, and the temperatures of the cells of both terminals are controlled. The Rukoto. Furthermore, as described in (2) above, if the cooling water flowing through the cooling water flow grooves of the separator is allowed to flow through the cooling water flow path provided in the electric insulating plate, the separator receives heat of the power generation reaction. The cooling water whose temperature has risen will flow through the cooling water flow path provided in the electric insulating plate, and the temperature of the cooling water flowing through the cooling water flow path provided in the electric insulating plate will be increased by the separator, i.e., the cells. Because it becomes several degrees higher than the temperature of the flowing cooling water,
This is effective in suppressing heat radiation from both terminals and suppressing a decrease in temperature of the unit cells located at both terminals, thereby obtaining battery characteristics equivalent to those of the other unit cells.

[0014]

FIG. 1 is a perspective view showing a basic structure of an electric insulating plate used in an embodiment of a solid polymer electrolyte fuel cell according to the present invention, and FIG. It is a schematic diagram which shows the example of a structure of the cooling water distribution path | route of the fuel cell laminated body comprised by incorporating the electric insulating plate.

As shown in FIG. 1, in the electric insulating plate 11A of this embodiment, as in the conventional example shown in FIG.
A gas flow path 16 for supplying the fuel gas and the oxidizing gas is disposed at an upper part, and a gas flow path 16 for discharging the fuel gas and the oxidizing gas is disposed at a lower part, respectively.
A cooling water supply flow path 17 for supplying cooling water to the separator is also arranged at the upper part as in the conventional example. The difference between the present embodiment and the conventional example shown in FIG.
A plurality of partitions 21 and a partition 2
A cooling water flow path comprising a plurality of flow grooves 22 extending in the direction of gravity separated by 1 is formed, and cooling water flowing through the plurality of cells 9 and the current collector plate 10 is formed at the lower end of the cooling water flow path. A groove inlet 19 to be introduced is provided, and a cooling water discharge flow path 18A for discharging cooling water flowing through the plurality of flow grooves 22 to the outside through the fastening plate 12 is provided at an upper end of the cooling water flow path. It is in.

The electric insulating plate 1 having the cooling water flow path of the present configuration
In the fuel cell stack formed using 1A, as shown schematically in FIG. 2, the cooling water is provided on the end face of the clamping plate 12 disposed at both ends of the stack. Introduced from the cooling water supply port which is not
After passing through the cooling water supply flow path provided in the current collecting plate 10, it is divided and passed through the cooling water distribution grooves provided in the separators of the plurality of unit cells 9, and is caused by the power generation reaction. Absorb heat and cool unit cells. The cooling water whose temperature has risen by absorbing the heat is merged into a flow path provided at the lower end in the direction of gravity, passes through a discharge flow path provided in the current collector plate 10, and is formed into a groove of the electric insulating plate 11A shown in FIG. After being introduced into the inlet 19 and flowing through the cooling water flow path composed of the plurality of flow grooves 22 extending in the above-described gravity direction, the cooling water flow path 18A is provided on the end face of the fastening plate 12 through the cooling water discharge flow path 18A. It is discharged to the outside from the cooling water discharge port.

Therefore, in this configuration, the electric insulating plates 11A disposed at both ends of the fuel cell stack are controlled in temperature by the cooling water whose temperature has been increased by absorbing the heat generated by the unit cells. It is possible to maintain the temperature of the unit cells located at both ends of the stacked body almost equal to the temperature of the unit cells located at the other central side, and to achieve a stable efficiency without causing a decrease in the battery characteristics due to the temperature decrease. It will be able to drive in a typical way.

[0018]

As described above, according to the present invention,
An electrode layer is adhered to both main surfaces of an electrolyte layer composed of a solid polymer electrolyte membrane to form a membrane electrode assembly, and a separator provided with a gas flow groove and a cooling water flow groove on both outer surfaces thereof is arranged. A unit cell is formed, a plurality of unit cells are stacked with the stacking direction arranged in the horizontal direction, and a current collecting plate for taking out generated DC electricity and electricity for maintaining electrical insulation are provided at both ends. After sequentially arranging the insulating plates, they are clamped and held by a clamping plate, and pressurized and held. In a solid polymer electrolyte fuel cell in which gas flows and is supplied to the electrode layer of the membrane electrode assembly to extract DC electricity generated from the current collector, (1) the electric insulating plate has Cooling water flowing through cooling water that controls battery temperature Channels, for example, are provided with a cooling water channel comprising a plurality of concave vertical grooves formed on the side surfaces of the electric insulating plate, so that the cooling water flows therethrough. Is maintained almost equal to the temperature of the other unit cells located on the center side, and a solid polymer electrolyte fuel cell that can operate stably and efficiently without causing a decrease in cell characteristics due to a temperature decrease is obtained. It became. I do.

(2) If the cooling water discharged through the cooling water flow groove of the separator is used as the cooling water flowing through the cooling water flow path provided in the electric insulating plate,
The temperature of the cells located at both ends of the fuel cell stack is effectively controlled by the cooling water whose temperature has risen due to the heat generated by the cells, so it is stable without lowering the cell characteristics due to the temperature drop It is suitable as a solid polymer electrolyte type fuel cell which can be efficiently operated.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a basic configuration of an electric insulating plate used in an embodiment of a solid polymer electrolyte fuel cell according to the present invention.

FIG. 2 is a schematic view showing a configuration example of a cooling water flow path of a fuel cell stack configured by incorporating the electric insulating plate of FIG. 1;

FIG. 3 is an exploded cross-sectional view schematically showing a configuration of a unit cell of a conventional solid polymer electrolyte fuel cell.

FIG. 4 is a side view schematically showing a configuration of a fuel cell stack of a conventional solid polymer electrolyte fuel cell.

FIG. 5 is a schematic view showing a configuration example of a cooling water flow path of a fuel cell stack of a conventional solid polymer electrolyte fuel cell.

FIG. 6 is a perspective view showing a configuration of an electric insulating plate used in a fuel cell stack of a conventional solid polymer electrolyte fuel cell.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Membrane electrode assembly 1A Electrolyte layer 1B Fuel electrode layer 1C Oxidizer electrode layer 2A, 2B Separator 3A, 3B Gas circulation groove 6A, 6B Cooling water circulation groove 10 Current collector plate 11A Electrical insulating plate 12 Tightening plate 16 Gas flow path 17 Cooling water supply flow path 18A Cooling water discharge flow path 19 Groove entrance 21 Partition wall 22 Communication groove

Claims (3)

[Claims] 1. A membrane electrode assembly is formed by adhering electrode layers to both main surfaces of an electrolyte layer comprising a solid polymer electrolyte membrane, and further having a gas flow groove and a cooling water flow groove on both outer surfaces thereof. A separator is arranged to constitute a unit cell, a plurality of unit cells are arranged in a stacking direction in a horizontal direction and stacked, and at both ends, a current collector plate for extracting generated DC electricity and an electrical insulation are provided. After sequentially arranging electrical insulating plates for holding, tightening by a fastening plate and holding under pressure, flowing cooling water through a cooling water flow groove to maintain the membrane electrode assembly at a preferable temperature, In a solid polymer electrolyte fuel cell, a fuel gas and an oxidizing gas are passed through and supplied to the electrode layer of the membrane electrode assembly to take out the DC electricity generated from the current collector plate. Cooling water that controls the temperature of the cell located at the terminal Solid polymer electrolyte fuel cell characterized by comprising a cooling water passage to flow. 2. The solid polymer electrolyte fuel cell according to claim 1, wherein the cooling water flow path provided on the electric insulating plate comprises a plurality of concave grooves formed on a side surface of the electric insulating plate. A solid polymer electrolyte fuel cell. 3. The solid polymer electrolyte fuel cell according to claim 1, wherein the cooling water flowing through the cooling water flow path provided on the electric insulating plate flows through the cooling water flow groove of the separator. A solid polymer electrolyte fuel cell, characterized in that the cooling water is discharged after cooling.