JP2009026644A - Solid polymer fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid polymer fuel cell in which inside temperature difference is small, and which is capable of effectively preventing dew formation of gas introduced from a gas introduction port. <P>SOLUTION: The fuel cell 1 is formed as a plurality of single cells 2 are laminated sequentially, a current collecting plate 3a, an insulating plate 4a, and a tightening plate 5a are sequentially laminated on the left side of these single cells 2, a current collector 3b, an insulating plate 4b, and a tightening plate 5b are sequentially laminated on the right side of the single cells 2, and these laminates are tightened by tightening tools 14. Then, fuel gas is introduced inside a stack from the tightening plate 5b of one side and discharged outside from the tightening plate 5a of the opposite side, and oxidant gas is introduced inside the stack from the tightening plate 5a of the side opposite to the fuel gas introduction side, and discharged outside from the tightening plate 5b of the fuel gas introduction side. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polymer electrolyte fuel cell using a membrane made of a fluorine-based polymer or a hydrocarbon-based polymer as an electrolyte membrane.

  As a kind of fuel cell, a flat battery having a fuel cell provided with a fuel electrode on one side of the electrolyte layer and an oxidant electrode on the other side, a separator provided with a fuel gas passage, and a separator provided with an oxidant gas passage Are stacked in the same direction, and a current collector plate and an electrical insulating plate are stacked on both ends of the stacked unit cells, respectively, and both ends of the stacked body are narrowed by a metal clamping plate. What you have is known. As one type of such a fuel cell, a solid polymer fuel cell using a membrane made of a fluorine-based polymer or a hydrocarbon-based polymer as an electrolyte membrane is known.

  In the above polymer electrolyte fuel cell, the fuel gas (hydrogen) and the oxidant gas (air) introduced from the gas inlet provided in the metal clamping plate due to the low operating temperature. Is easy to condense on the clamping plate, and water generated by the dew condensation causes gas diffusion in the fuel electrode and oxidant electrode (oxygen electrode) and gas flow in the gas passage provided outside the fuel electrode and oxidant electrode. An obstruction occurs. When such a situation occurs, an electrochemical reaction between the fuel gas and the oxidant gas hardly occurs in the single battery cell, and the output decreases.

  Therefore, the insulating plates to be laminated on both the left and right sides of the laminated unit cells (stack) are formed of a material having low thermal conductivity such as polycarbonate, fluorine resin, FRP, etc., and fuel gas and oxidation are formed on the side surfaces of those insulating plates. A polymer electrolyte fuel cell has been developed in which the agent gas inlet is provided to suppress the dew condensation of the gas at the gas inlet (Patent Document 1).

JP-A-9-120833

  According to the polymer electrolyte fuel cell of Patent Document 1, it is possible to suppress the condensation of gas at the gas inlet to some extent. However, in the polymer electrolyte fuel cell of Patent Document 1, since a metal current collector plate plated with copper is laminated inside the insulating plate, the unit cell adjacent to the current collector plate is: The temperature will be lower than in the center. Therefore, in those single cells, the dew condensation of the gas in the gas passage cannot be sufficiently suppressed, and the power generation efficiency is deteriorated.

  The object of the present invention is to eliminate the above-mentioned problems of the conventional polymer electrolyte fuel cell, and to extremely effectively prevent the dew condensation of the gas introduced from the gas inlet through a very small internal temperature difference. It is an object of the present invention to provide a polymer electrolyte fuel cell that can be used.

  Among the present inventions, the invention described in claim 1 includes a fuel cell in which a fuel electrode is provided on one side of an electrolyte layer made of a polymer film and an oxidant electrode is provided on the other side, and a fuel gas passage. A plurality of flat unit cells having a separator and a separator provided with an oxidant gas passage are stacked in the same direction, and a current collecting plate and an electric insulating plate are stacked on both ends of the stacked unit cells, respectively. , A polymer electrolyte fuel cell in which both ends of the laminate are sandwiched by metal clamping plates, and the fuel gas is introduced into the unit cell from one clamping plate on the opposite side The oxidant gas is introduced into the unit cell from the clamping plate on the side opposite to the fuel gas introduction side, and discharged from the clamping plate on the fuel gas introduction side to the outside. It is characterized by this.

  The invention described in claim 2 is the invention described in claim 1, wherein one of the clamping plates is provided with a fuel gas discharge passage inside the center of the plate in the thickness direction, and the other This fastening plate is characterized in that an oxidizing gas discharge passage is provided inside the center of the plate in the thickness direction.

  In the polymer electrolyte fuel cell according to claim 1, the fuel gas supplied for power generation is heated to the inside of a unit cell stack (so-called stack), and then guided to a clamping plate on one side. The clamping plate is heated by heat conduction. At the same time, the oxidant gas supplied for power generation is heated through the inside of the stack and then guided to the clamping plate on the side opposite to the fuel gas discharge side to heat the clamping plate by heat conduction. To do. Therefore, according to the polymer electrolyte fuel cell of the present invention, since the temperature drop of the entire stack is suppressed, it is possible to prevent the voltage drop of the stack and to generate power very efficiently.

  According to the polymer electrolyte fuel cell of claim 2, since the temperature difference between the outer side and the inner side (stack side) of the clamping plate is reduced, the dew condensation of the gas at the introduction port of the fuel gas and the oxidant gas is extremely high. Since it is efficiently prevented, the so-called fretting phenomenon does not occur and the generated voltage can be stabilized.

  Hereinafter, an embodiment of a polymer electrolyte fuel cell (hereinafter simply referred to as a fuel cell) according to the present invention will be described in detail with reference to the drawings. 1 to 4 show a front surface, a plane surface, a rear surface, and a left side surface of a fuel cell according to the present invention. The fuel cell 1 includes a plurality of single cells 2, 2,. 2. Current collecting plates 3a, 3b for taking out DC power generated by 2 ..., single cells 2, 2 .... and insulating plates 4a, 4b for insulating current collecting plates 3a, 3b from the outside, single cells 2, 2.., Clamping plates 5a and 5b for sandwiching the current collector plates 3a and 3b and the insulating plates 4a and 4b, fastening tools 14 and 14 made of long bolts and nuts, etc. ing.

  FIG. 5 is an explanatory view showing a vertical cross section of the unit cell 2, and the unit cell 2 is composed of fuel cells 9, separators 10 a and 10 b, a seal member 13, and the like. The fuel cell 9 includes an electrolyte layer 6 made of a thin rectangular solid polymer film, a fuel electrode 7 made of a catalyst layer containing a catalytically active substance, and an electrode base material that provides fuel gas supply, discharge, and current collecting functions, It is constituted by an oxidant electrode 8 composed of a catalyst layer containing a catalytically active substance and an electrode base material having functions of supplying, discharging and collecting current of oxidant gas.

  The separator 10a is made of a gas-impermeable material, and includes a plurality of fuel gas passages 11 on the surface joined to the fuel electrode 7 for circulating fuel gas. Similarly to the separator 10a, the separator 10b is formed of a gas-impermeable material, and has a plurality of oxidant gas passages 12 for circulating the oxidant gas on the surface joined to the oxidant electrode 8. Yes.

  In the unit cell 2, a rubber seal 13 for preventing gas leakage from the fuel gas passage 11 and the oxidant gas passage 12 is fitted into the concave portions on the periphery of the separators 10 a and 10 b and the concave portion on the periphery of the fuel cell 9. In this state, separators 10a and 10b are stacked on the front and back sides of the fuel cell 9, respectively.

  The fuel cell 1 sequentially stacks a plurality of unit cells 2, 2... Configured as described above, and on the left side of the unit cells 2, 2,. The clamping plates 5a are sequentially stacked, and the current collector plate 3b, the insulating plate 4b, and the clamping plate 5b are sequentially stacked on the right side of the cells 2, 2,. It is formed by applying an appropriate pressure and tightening by 14.

  Also, a metal fuel gas inlet 15 for introducing fuel gas (hydrogen) into the inside is provided above the center of the outer surface of the fastening plate 5b located on the right side, and the fastening plate located on the left side is provided. A metallic oxidant gas inlet 16 for introducing an oxidant gas (air) into the interior is provided above the center of the outer surface of the attached plate 5a. As shown in FIG. 2, the fuel gas inlet 15 is provided rearward from the center, and the oxidant gas inlet 16 is provided forward from the center.

  FIG. 6 shows a vertical cross section in the vicinity of the installation portion of the oxidant gas introduction port 16. The fastening plate 5 a, the insulating plate 4 a, the current collector plate 3 a, and the plurality of single cells 2, 2. Is formed with a horizontal communication hole 17 communicating with the oxidant gas introduction port 16. Then, the oxidant gas introduced from the oxidant gas introduction port 16 is sent to the single cells 2 through the communication holes 17. In addition, a seal member 18 is disposed on the outer peripheral portion of the communication hole 17 of the fastening plate 5a, the insulating plate 4a, and the current collector plate 3a to prevent leakage of the oxidant gas flowing through the communication hole 17 to the outside. Has been. The structure in the vicinity of the installation portion of the fuel gas introduction port 15 is the same as that in the vicinity of the installation portion of the oxidant gas introduction port 16 described above, and the fuel gas introduced from the fuel gas introduction port 15 is connected to the communication hole 17. It is sent to each single cell 2, 2,.

  On the other hand, as shown in FIGS. 1, 2, and 4, below the center of the front surface of the clamping plate 5 a located on the left side, is made of a metal for discharging the fuel gas (hydrogen) that has passed through the inside to the outside. A fuel gas discharge port 19 is provided, and is in a state of communicating with a fuel gas discharge path 21 provided horizontally inside the fastening plate 5a. Further, as shown in FIGS. 2, 3, and 4, below the center of the rear surface of the clamping plate 5b located on the right side, a metal made for discharging the oxidant gas (air) that has passed through the inside to the outside. The oxidant gas discharge port 20 is provided, and is in communication with an oxidant gas discharge path 22 provided horizontally inside the fastening plate 5b. The fuel gas discharge passage 21 and the fuel gas discharge port 19 are located slightly inside from the center in the thickness direction of the fastening plate 5a, and the oxidant gas discharge passage 22 and the oxidant gas discharge port 20 are tightened. It is located slightly inside from the center in the thickness direction of the plate 5b.

  FIG. 7 shows a vertical cross section in the vicinity of the installation portion of the fuel gas discharge passage 21, and the base end portion of the fuel gas discharge passage 21 is bent vertically inwardly. Through the bent portion, the fastening plate 5a, the insulating plate 4a, the current collecting plate 3a, and a horizontal communication hole 23 formed in the plurality of single cells 2, 2,... In addition, a seal member 18 is disposed on the outer peripheral portion of the communication hole 23 of the fastening plate 5a, the insulating plate 4a, and the current collector plate 3a in order to prevent leakage of fuel gas flowing through the communication hole 23 to the outside. ing. Then, the fuel gas that has passed through the single cells 2, 2,... Is led to the fuel gas discharge path 21 through the communication hole 23, and is discharged from the fuel gas discharge port 19 to the outside. The structure in the vicinity of the installation portion of the oxidant gas discharge path 22 is the same as the structure in the vicinity of the installation section of the fuel gas discharge path 21, and the oxidant gas that has passed through the single cells 2, 2,. It is guided to the oxidant gas discharge path 22 through the hole 23 and is discharged from the oxidant gas discharge port 20 to the outside.

  In the fuel cell 1 configured as described above, the unit cell 2 in which the fuel gas (hydrogen) guided from the fuel gas inlet 15 provided in the right clamping plate 5 b is stacked via the communication hole 17. , 2..., And flows down through the fuel gas passage 11 inside each unit cell 2,... By the pressure (that is, the fuel gas gradually flows downward to the left). Then, power is generated by electrochemically reacting with the oxidant gas as it flows down. Further, the remaining fuel gas that has not contributed to the reaction passes through the communication hole 23 and is led to the fuel gas discharge passage 21 provided in the left clamping plate 5a and discharged to the outside from the fuel gas discharge port 19. The On the other hand, the oxidant gas (air) guided from the oxidant gas inlet 16 provided in the left clamping plate 5a is sent to the stacked unit cells 2, 2,. , The pressure causes the oxidant gas passage 12 inside each unit cell 2, 2,... To flow down (that is, the oxidant gas gradually flows downward to the right). Then, power is generated by electrochemically reacting with the fuel gas as it flows down. Further, the remaining oxidant gas that has not contributed to the reaction is led to the oxidant gas discharge path 22 provided in the right clamping plate 5b through the communication hole 23 and is externally supplied from the oxidant gas discharge port 20. Is discharged.

  In the fuel cell 1, as described above, the fuel gas is introduced into the stack from the one side clamping plate 5b and discharged to the outside from the opposite side clamping plate 5a, and the oxidant gas is supplied to the fuel gas introduction side. It is introduced into the stack from the opposite side clamping plate 5a and discharged from the fuel gas introduction side clamping plate 5b to the outside. Therefore, after the fuel gas supplied for power generation is heated through the inside of the stack, the fuel gas is guided to the one clamping plate 5a to heat the clamping plate 5a by heat conduction, and for power generation. After being heated through the stack, the oxidant gas supplied to is guided to the clamping plate 5b on the side opposite to the fuel gas discharge side and heats the clamping plate 5b by heat conduction. Therefore, according to the fuel cell 1, the temperature difference between the center of the stack and the left and right end portions is smaller than that of the conventional solid polymer fuel cell, and the temperature drop of the entire stack is suppressed. For this reason (see FIG. 5), it is difficult for the voltage to decrease due to the temperature decrease of the stack, and it is possible to generate power very efficiently.

  Further, since the fuel cell 1 has a very small temperature difference between the outer side and the inner side (stack side) of the clamping plates 5a and 5b, the fuel gas and the oxidant gas at the fuel gas inlet 15 and the oxidant gas inlet 16 Therefore, the so-called fretting phenomenon does not occur and stable power generation can be performed.

  The configuration of the fuel cell (solid polymer fuel cell) according to the present invention is not limited to the embodiment described above, but includes a single cell, a current collector plate, an insulating plate, a clamping plate, a fuel gas. The configuration of the introduction port, the oxidant gas introduction port, the fuel gas discharge port, the oxidant gas discharge port, and the like can be appropriately changed as necessary without departing from the spirit of the present invention.

  For example, the fuel gas inlet, oxidant gas inlet, fuel gas outlet, and oxidant gas outlet provided in the fuel cell are not limited to those made of metal, but are changed to those made of synthetic resin or ceramics It is also possible to do. Further, the fuel cell is not limited to a cell body, a current collector plate, and a laminate composed of an insulating plate sandwiched between a pair of left and right clamping plates as in the above embodiment. It is also possible to change the laminated body made of plates to one covered with a rectangular parallelepiped housing or the like.

  Since the fuel cell (solid polymer fuel cell) of the present invention has excellent effects as described above, it can be suitably used for various applications.

It is a front view of a fuel cell (solid polymer fuel cell). It is a top view of a fuel cell. It is a rear view of a fuel cell. It is a left view of a fuel cell. It is explanatory drawing which shows the vertical cross section of a cell. It is explanatory drawing which shows the vertical cross section of the installation part vicinity of an oxidizing agent gas inlet. It is explanatory drawing which shows the vertical cross section of the installation part vicinity of a fuel gas discharge path. It is explanatory drawing which shows the relationship between the position inside a stack, and temperature (A is a thing of the conventional solid polymer fuel cell, B is a thing of the polymer electrolyte fuel cell of this invention).

Explanation of symbols

1. Fuel cell (solid polymer fuel cell)
2 .... Cells 3a, 3b ... Current collectors 4a, 4b ... Insulation plates 5a, 5b ... Fastening plates 15 .... Fuel gas inlet 16 .... Oxidant gas inlet 19 .... Fuel gas outlet 20 .. Oxidant gas outlet

Claims (2)

A flat battery having a fuel cell provided with a fuel electrode on one side of an electrolyte layer made of a polymer membrane and an oxidant electrode on the other side, a separator provided with a fuel gas passage, and a separator provided with an oxidant gas passage A plurality of unit cells are stacked in the same direction, and a current collector plate and an electric insulating plate are stacked on both ends of the stacked unit cells, respectively, and both ends of the stacked body are attached by metal clamping plates. A polymer electrolyte fuel cell sandwiched between
Fuel gas is introduced into the unit cell from one side of the clamping plate and discharged to the outside from the opposite side of the clamping plate,
A solid polymer fuel cell, characterized in that an oxidant gas is introduced into a single cell from a clamping plate on the side opposite to the fuel gas introduction side and discharged to the outside from the clamping plate on the fuel gas introduction side.   One clamping plate is provided with a fuel gas discharge passage inside the center of the plate in the thickness direction, and the other clamping plate discharges oxidant gas inside the center of the plate in the thickness direction. 2. The polymer electrolyte fuel cell according to claim 1, wherein a path is provided.

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