JPH06267564A - Solid high polymer electrolyte fuel cell - Google Patents

Abstract

PURPOSE:To enable cell reaction to be stably kept on by facilitating exhaust of generated water and moving water at the side of a cathode, and also facilitating dispersion of oxygen gas within oxidant. CONSTITUTION:The cell is equipped with a laminated body 31 where an anode 33 and a cathode 34 are provided for both the surfaces of an electrolyte 32 respectively, a fuel distributing plate 37 which is provided for the anode 33 side of the aforesaid laminated body 31 while being provided with a fuel flow path 36 feeding fuel to the anode 33, and with an oxidant distributing plate 40 which is provided for the cathode side of the aforesaid laminated body 31 while being provided with an oxidant flow path 39 feeding oxidant to the aforesaid cathode 34. And at least either of the depth or the width of the oxidant flow path 39 of the aforesaid oxidant distributing plate 40 is made gradually small along the flow path area of oxidant from the upstream area to the downstream area.

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 in which an oxidant flow path of an oxidant distribution plate is improved.

[0002]

2. Description of the Related Art A solid polymer electrolyte fuel cell uses a polymer ion exchange membrane (for example, a fluororesin ion exchange membrane having a sulfonic acid group) as an electrolyte 1 as shown in FIG.
It has an electrode assembly 6 structure provided with catalyst electrode layers (for example, platinum) 2, 3 and porous carbon electrodes 4, 5 on both sides.
Hydrogen in the humidified fuel supplied to the anode electrode side is hydrogen-ionized on the catalyst electrode (anode electrode) 2, and the hydrogen ions pass through the electrolyte 1 in the presence of water to form H ^+. As xH ₂ O, it moves to the cathode side together with water.

The transferred hydrogen ions are transferred to the catalyst electrode (cassette).
Oxygen in the oxidizer and the external circuit 7
Reacts with the incoming electrons to produce water, and the produced water is caustic.
It is discharged from the cathode 3 to the outside of the fuel cell. this
At this time, the electric current flowing through the external circuit 7 is converted into a direct current energy
Available as a ghee. It should be noted that the polymer 1 that serves as the electrolyte 1
In the on-exchange membrane, hydrogen ion permeability as described above
In order to achieve this, keep this membrane in a state of sufficient water retention.
It must be kept in the fuel or oxidizer
Including saturated steam equivalent to the operating temperature of
Humidifying and supplying the fuel and the oxidant to the electrode assembly 6,
I try to keep water retention. Below, the high solid content
The reaction formula in the child electrolyte fuel cell is shown. Anode side: H₂→ 2H⁺ + 2e^-  Cathode side: (1/2) O₂+ 2H⁺ + 2e^- → H₂O Total reaction: H₂+ (1/2) O₂→ H₂O FIGS. 2 (A), (B), and (C) show conventional solid polymer electrolysis.
1 shows an example of the structure of a high quality fuel cell.

Reference numeral 11 in the figure is a laminate in which a first catalyst electrode (anode electrode) 13 and a second catalyst electrode (cathode electrode) 14 are laminated on and under an electrolyte 12. A fuel distribution plate 17 having a fuel flow path 16 is provided on the upper side of the laminated body 11 via a porous first carbon electrode (anode electrode) 15. An oxidant distribution plate 20 having an oxidant flow channel 19 under the laminated body 11 via a porous second carbon electrode (cathode electrode) 18
Are provided respectively. Here, the oxidant channel 19 has a constant groove width and a constant groove depth (d ₁ = d ₂ ) and a constant cross-sectional area. Note that d ₁ is the depth of the groove on the oxidant inlet side, d
₂ shows the depth on the oxidant outlet side.

In the fuel cell having such a structure,
The fuel hydrogen flowing through 16 passes through the first carbon electrode 15 and is hydrogen-ionized on the first catalyst electrode 13, and the hydrogen ions are H ^{+ in the} electrolyte 12 with the interposition of water. ・ As xH ₂ O,
It moves to the cathode side together with water. The water generated on the second catalyst electrode 14 by the hydrogen ions and the water that has moved in the electrolyte 12 from the anode side together with the hydrogen ions are vapor or partly in the liquid state and the second carbon electrode 18 is discharged. It is configured to pass through and be discharged into the oxidant flowing in the oxidant channel 19 having a constant cross-sectional area from the upstream channel region to the downstream channel region.

[0006]

However, as shown in FIG. 2, when the flow channel width is constant and the groove depth is constant (d ₁ = d ₂ ) from the upstream flow channel region toward the downstream flow channel region. In the solid polymer electrolyte fuel cell having the oxidizer distribution plate 20 having a uniform area flow path, the generated water generated by the cell reaction and the moving water moving from the anode electrode to the cathode electrode along with hydrogen ions Since the partial pressure of water vapor in the oxidant atmosphere increases toward the downstream region of the oxidant flow path 19, it becomes difficult for the gas to be diffused and discharged as vapor. Therefore, part of the vapor that is liquefied or formed into liquid drops is clogged in the porous second carbon electrode 18 on the cathode side, and the generated water or moving water is oxidized in the porous second carbon electrode 18. The structure was such that the gas diffusion of was likely to be blocked.

The present invention has been made in consideration of such circumstances, and at least one of the depth and the width of the oxidant flow passage of the oxidant distribution plate is set from the upstream flow passage region to the downstream flow passage region of the oxidant. By gradually decreasing it, the flow velocity in the downstream flow passage area of the oxidizer flow passage becomes faster, and the generated water and vaporized water that have become vapor are easily diffused and discharged into the gas, or partly liquefied or liquefied. It is possible to blow off the generated water and the moving water existing in the porous carbon electrode, which makes it possible to discharge the generated water and the moving water on the cathode side, and at the same time, the gas diffusion of oxygen in the oxidant becomes good. An object of the present invention is to provide a solid polymer electrolyte fuel cell capable of continuously performing a stable cell reaction.

[0008]

According to the present invention, there is provided a laminated body in which an anode electrode and a cathode electrode are arranged on both surface sides of an electrolyte, and an anode electrode side of the laminated body, and fuel is supplied to the anode electrode. A fuel distribution plate having a fuel flow path,
An oxidant distribution plate having an oxidant flow channel that is provided on the cathode side of the laminate and supplies an oxidant to the cathode electrode, and the depth of the oxidant flow channel of the oxidant flow distribution plate or The solid polymer electrolyte fuel cell is characterized in that at least one of the widths is gradually reduced from the upstream flow passage region of the oxidant along the downstream flow passage region.

[0009]

In the solid polymer electrolyte fuel cell, the oxidizer is reduced by reducing the cross-sectional area of the oxidizer flow passage of the oxidizer distribution plate to which the oxidizer is supplied from the upstream flow passage region toward the downstream flow passage region. Even if the flow velocity in the downstream flow path area of the gas becomes faster and the partial pressure of water vapor in the oxidant atmosphere rises, the generated water that became vapor and the moving water are easily diffused and discharged. It becomes possible to blow off the generated water and the moving water existing in the porous carbon electrode by partially liquefying or liquefying. With these aids, discharge of generated water and moving water on the cathode side of the battery is improved,
Further, the gas diffusion of oxygen in the oxidant becomes good, and a stable battery reaction can be maintained.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will now be described with reference to FIG.
This will be described with reference to (B) and (C). Here, FIG.
(A) is a front view of a solid polymer electrolyte fuel cell, FIG.
FIG. 1B is a side view of the fuel cell viewed from the oxidant inlet side, and FIG. 1C is a side view of the fuel cell viewed from the oxidant outlet.

Reference numeral 31 in the drawing is a laminate in which a first catalyst electrode (anode electrode) 33 and a second catalyst electrode (cathode electrode) 34 are laminated on and under an electrolyte 32. A fuel distribution plate 37 having a fuel flow path 36 is provided on the upper side of the laminated body 31 via a porous first carbon electrode (anode electrode) 35. An oxidant distribution plate 40 having an oxidant flow path 39 through a porous second carbon electrode (cathode electrode) 38 is provided below the laminated body 31.
Are provided respectively. Here, the depth of the oxidant channel 39 is a depth d ₁ on the oxidant inlet side and a depth d ₂ on the oxidant outlet side.
Then, d ₁ > d ₂ , and the diameter gradually decreases from the oxidant inlet side to the oxidant outlet side.

In the fuel cell having such a structure, the fuel hydrogen flowing through the fuel flow path 36 passes through the first carbon electrode 35 and is hydrogen-ionized on the first catalyst electrode 33. Under intervention H ⁺ ・ As xH ₂ O,
It moves to the cathode side together with water. The water generated by the hydrogen ions on the second catalyst electrode 34 and the water that has moved in the electrolyte 32 together with the hydrogen ions from the anode side are the same as those of the oxidizing agent even if the water vapor partial pressure in the oxidizing agent atmosphere is high. Due to the high gas flow rate, vapor or part of it remains liquid
It is designed to be discharged into the oxidant that has passed through the carbon electrode 38 and flown in the oxidant channel 39.

According to the above embodiment, the depth of the oxidant flow channel 39 is gradually reduced from the oxidant inlet side (depth d ₁ ) to the oxidant outlet side (depth d ₂ ). Therefore, the cross-sectional area of the oxidant flow channel 39 decreases from the upstream flow channel region toward the downstream flow channel region. Therefore, due to the generated water or the moving water discharged in the upstream flow channel area of the oxidant flow channel 39, the oxidant flow channel 39
In the downstream flow passage region of, the water vapor partial pressure in the oxidant atmosphere increases, but the flow velocity of the oxidant in the downstream flow passage region becomes faster,
The generated water or mobile water that has become vapor is easily diffused and discharged, or due to the high flow rate of the oxidant gas, the generated water or mobile water partially liquefied or formed into droplets and present in the porous carbon electrode is removed. You will be able to blow it away. Due to these aids, the generated water and mobile water on the cathode side of the battery are discharged well, and the gas diffusion of oxygen in the oxidant is also improved, enabling a stable battery reaction to continue. is there.

In the above embodiment, the depth of the oxidant flow path is set to gradually decrease from the oxidant inlet side to the oxidant outlet side, but the present invention is not limited to this.
For example, the width of the oxidant channel is gradually reduced from the oxidant inlet side to the oxidant outlet side, or the depth and width of the oxidant channel are simultaneously reduced from the oxidant inlet side to the oxidant outlet side. The configuration may be gradually reduced.

[0015]

As described above in detail, according to the present invention, at least one of the depth and the width of the oxidant flow passage of the oxidant flow distribution plate is set from the upstream flow passage region to the downstream flow passage region of the oxidant. By gradually decreasing the flow velocity in the downstream flow passage of the oxidizer flow passage, the generated water and vaporized water that have become vapor are easily diffused and discharged, or partly liquefied or formed into droplets and become porous. It is possible to blow off the generated water and the moving water existing in the high quality carbon electrode, and thus the discharge of the generated water and the moving water on the cathode side is good, and the gas diffusion of oxygen in the oxidant is also good, A solid polymer electrolyte fuel cell capable of continuously performing stable cell reaction can be provided.

[Brief description of drawings]

1 is an explanatory view of a solid polymer electrolyte fuel cell according to an embodiment of the present invention, FIG. 1 (A) is a front view, and FIG.
1B is a side view seen from the oxidant inlet side, and FIG. 1C is a side view seen from the oxidant outlet.

FIG. 2 is an explanatory view of a conventional solid polymer electrolyte fuel cell, FIG. 2 (A) is a front view, FIG. 2 (B) is a side view seen from the oxidant inlet side, and FIG. 2 (C) is oxidation. The side view seen from the agent outlet is shown.

FIG. 3 is a diagram for explaining the function of a solid polymer electrolyte fuel cell.

[Explanation of symbols]

31 ... Laminate, 32 ... Electrolyte, 33
... first catalyst electrode, 34 ... second catalyst electrode, 35 ... first carbon electrode, 36 ... fuel flow path, 37 ... fuel distribution plate,
38 ... 2nd carbon electrode, 39 ... Oxidizing agent flow path, 40 ... Oxidizing agent distribution plate.

Claims (1)

[Claims] 1. A fuel distribution system having a laminate in which an anode electrode and a cathode electrode are arranged on both sides of an electrolyte, and a fuel flow path which is provided on the anode electrode side of the laminate and which supplies fuel to the anode electrode. A plate and an oxidant distribution plate provided on the cathode side of the laminate and having an oxidant flow channel for supplying an oxidant to the cathode electrode, wherein the oxidant flow channel of the oxidant flow distribution plate is A solid polymer electrolyte fuel cell, characterized in that at least one of depth and width is gradually reduced from an upstream channel region of an oxidant along a downstream channel region.