Gas separator for solid high polymer electrolytic fuel cell

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Industrial application field]

The present invention relates to a gas separator for a polymer electrolyte fuel cell, which can maintain a sufficiently water-retaining state of the electrolyte and stabilize the output of the fuel cell.

【0002】

[Conventional technology]

Figure 3 shows an example of a polymer electrolyte fuel cell. A polymer ion exchange membrane (for example, a fluororesin-based ion exchange membrane having a sulfonic acid group) is used as the electrolyte 01, and catalyst electrodes (for example, platinum) 02,03 are attached to both sides with this as the center, and both sides are porous. The electrode joint body 06 is formed by sandwiching the quality carbon electrodes 04 and 05 in a sandwich shape.

【0003】

Here, hydrogen (H) in the fuel supplied to the anode electrode side₂) Is hydrogen ionized on the catalyst electrode (anode electrode) 02, and the hydrogen ions are H in the electrolyte 01 under the intervention of water.⁺ XH₂Moves to the cathode pole side as O. The transferred hydrogen ions are oxygen (O) in the oxidant on the catalyst electrode (cathode electrode) 03.₂) And the electrons (e) that have been distributed in the external circuit 07^-), And the generated water is discharged to the outside of the fuel cell from the cathode electrodes 03 and 05. At this time, the electrons (e) that circulated in the external circuit 07^-) Flow can be used as DC electrical energy.

【0004】

In addition, in the polymer ion exchange membrane serving as the electrolyte 01, in order to realize the hydrogen ion permeability as described above, it is necessary to always keep the membrane in a sufficient water retention state, and usually fuel or oxidation. The agent is impregnated with saturated water vapor equivalent to the operating temperature of the battery (normal temperature to about 100 ° C), that is, humidified to supply the fuel and the oxidizing agent to the electrode joint 06 to maintain the water-retaining state of the membrane. I'm trying.

【0005】

FIG. 2 shows an example of the flow path shape of the separator (distribution plate) of the conventional polymer electrolyte fuel cell. The fuel or oxidant supplied from outside the fuel cell body is introduced into the inlet-side fluid manifold (header) 011 through the fluid introduction hole 09. The fuel or oxidant introduced into the inlet-side fluid manifold (header) 011 is distributed and flows through the inlet-side fluid communication hole 013 to the fluid flow path groove 015 provided on the back surface of the separator 08. In the figure, reference numeral 016 illustrates the flow of gas.

【0006】

The electrode joint 06 shown in FIG. 3 described above is held by a separator 08 having a fluid flow path groove 015 as shown in FIG. 2 from both sides. Here, the residual fuel or residual oxidant remaining not used in the battery reaction is collected again in the outlet-side fluid manifold 012 on the back surface of the separator 08 through the outlet-side fluid communication hole 014, and is collected again in the outlet-side fluid manifold 012 through the fluid discharge hole 010. It was discharged to the outside.

【0007】

[Problems to be Solved by the Invention]

The flow path shape of the separator (distribution plate) of the polymer electrolyte fuel cell shown in FIG. 2 described above has the following problems.

【0008】

(1) When fuel is passed through the separator, H in the electrolyte 01 is mixed with the hydrogen ions generated on the catalyst electrode (anode electrode) 02.⁺ XH₂As O, the humidified water in the fuel that has moved together to the catalyst electrode (cathode electrode) 03 side is steam or partly liquid together with the reaction water generated on the catalyst electrode (cathode electrode) 03 by this hydrogen ion. As it is, it is discharged into the fluid flow path groove 015 through which the oxidizing agent flows.

【0009】

At this time, a sufficient amount of humidified water in the fuel is still secured on the upstream side of the fluid flow path groove 015 through which the fuel flows, and sufficient humidified water is sufficient to move in the electrolyte and be discharged to the oxidant side. The amount is retained in the fuel, that is, the electrolyte can be maintained in a sufficiently water-retaining state, but on the downstream side of the fluid flow path groove 015 through which the fuel flows, the humidified water in the fuel is oxidized. There is a problem that the amount of humidified water gradually becomes insufficient due to the movement / permeation to the agent side, that is, the upstream side becomes slightly dry.

【0010】

As a result, the conductivity in the electrolyte is lowered on the downstream side of the fluid flow path groove 015, which causes the output of the fuel cell to be lowered.

【0011】

(2) When an oxidant is passed through the separator 08 having a fluid flow path shape as shown in FIG. 2, the catalyst electrode (anode electrode) 02 is used together with the generated water and hydrogen ions generated by the battery reaction. As the moving water moving to (cathode electrode) 03 moves toward the downstream part of the fluid flow path groove 015 through which the oxidant flows, the partial pressure of water vapor in the oxidant atmosphere rises, so that the water is diffused and discharged as steam. There is a problem that it becomes difficult.

【0012】

Further, the generated water or moving water that is partially liquefied or dropletized is clogged in the porous carbon electrode (cathode electrode) 05, which tends to hinder the gas diffusion in the carbon electrode 05. I'm here. For this reason, there has been a situation in which it is difficult for a stable battery reaction to occur.

【0013】

In view of the above problems, the present invention provides a gas separator for a polymer electrolyte fuel cell capable of maintaining the electrolyte in a sufficient water retention state to maintain the conductivity of the electrolyte, that is, to stabilize the fuel cell output. The purpose is.

【0014】

[Means for solving problems]

The separator for a solid polymer electrolyte fuel cell according to the present invention, which solves the above problems, is a separator for gas for supplying fuel gas or oxidant gas to the solid polymer electrolyte membrane of the fuel cell, and uses fuel or an oxidant. The flow path through which the fuel or oxidant that communicates with the manifold that collects the residual fuel or residual oxidant from the distribution / supply manifold is a curved flow path that is continuous for at least one round trip and a half, and a plurality of the flow paths are provided. It is characterized by being.

【0015】

[Action]

The flow path of the separator through which the fuel or oxidant flows was directed from the manifold side where the fuel or oxidant was distributed and supplied to the manifold side where the residual fuel or the residual oxidant was collected, and one flow path was continuously reciprocated at least once and a half. As a result of forming the flow path, the following actions are obtained. (1) In the flow path where the fuel flows, especially in the situation of insufficient humidifying water of the electrolyte on the downstream side, the situation from the upstream part of the adjacent curved flow path through which the fuel still has sufficient humidifying water flows. Since the situation is supplemented by the humidified water, it is possible to maintain the electrolyte in a sufficiently water-retaining state almost uniformly over the entire surface of the electrolyte. (2) The reciprocating flow path increases the flow velocity of the oxidant flowing through the flow path, and as a result, the generation generated by the battery reaction, especially on the downstream side where the partial pressure of water vapor in the oxidant atmosphere is high. Evaporation and gas diffusion of moving water moving from the catalyst electrode (anode electrode) to the catalyst electrode (cathode electrode) together with water and hydrogen ions into the oxidant are promoted. (3) The discharge of generated water in the liquefied or dropletized porous carbon electrode (cathode electrode) and moving water into the oxidant is also promoted, and the oxidant in the carbon electrode (cathode electrode) is promoted. Gas diffusion is also promoted.

【0016】

[Example]

Hereinafter, the present invention will be described based on examples.

【0017】

FIG. 1 is a schematic view of the flow path shape of the gas separator of the polymer electrolyte fuel cell according to the embodiment. As shown in FIG. 1, in the gas separator 8 according to the present embodiment, the residual fuel or the residual oxidant is formed in the fluid flow path groove of the separator through which the fuel or the oxidant flows from the manifold side in which the fuel or the oxidant is distributed and supplied. An embodiment in which one flow path is continuously made one and a half reciprocations toward the manihole side to collect the two flow paths and four flow paths are provided will be described.

【0018】

The fuel or oxidant supplied from outside the fuel cell body is introduced into the inlet-side fluid manifold 11 through the fluid introduction hole 9. The fuel or oxidant introduced into the inlet-side fluid manifold 11 is distributed and flows through the inlet-side fluid communication hole 13 to the fluid flow path groove 15 as a flow path provided on the back surface of the separator 8. .. As shown in FIG. 3 described above, the electrode joint body 06 takes a form of being held from both sides by the separator 8 surfaces having the fluid flow path groove 15. Here, the fluid flow path groove 15 into which the fuel or the oxidant is introduced is inverted once in the vicinity of the outlet side fluid manifold 12, guided to the vicinity of the inlet side fluid manifold 11 again, and further inverted once again, resulting in one reciprocation. After forming a half continuous flow path, it is directly connected to the outlet side fluid manifold 12. Therefore, the introduced fuel or oxidant gas flow 16 flows in opposition to each other in the fluid flow path groove 15.

【0019】

In this embodiment, an example is shown in which four such one-passages that are reciprocated and half-reciprocated are provided, as compared with the twelve linear flow paths shown in FIG. 2, which shows the above-mentioned conventional example. If the flow rate of the supplied fluid is constant and the width and depth of the fluid flow path groove are constant, the reciprocating fluid flow velocity in the groove will be tripled. Similarly, the fluid flow velocity in the fluid flow path groove 15 can be arbitrarily selected depending on the number of times the flow path is bent and the number of one flow path thereof. In this embodiment, the fluid flow path groove 15 is reciprocated and a half, but the present invention is not limited to this, and the number of bends may be increased.

【0020】

The residual fuel or residual oxidant remaining unutilized in the battery reaction is collected again in the outlet side manifold 12 on the back surface of the separator 8 through the outlet side fluid communication hole 14, and the fluid is collected outside the fuel cell body through the fluid discharge hole 10. Is discharged to.

【0021】

As a result, according to this embodiment, the following actions and effects are obtained.

【0022】

(1) The situation of insufficient humidified water content of the electrolyte, especially on the downstream side of the fluid flow path groove where fuel flows, is from the upstream part of the adjacent fluid flow path groove 15 through which fuel still has sufficient humidified water. Since it is supplemented by the humidified moisture of the electrolyte, it is possible to maintain the electrolyte in a sufficiently water-retaining state almost uniformly over the entire surface of the electrolyte, and as a result, the conductivity of the electrolyte is maintained, that is, the output of the fuel cell. It can be stabilized. (2) Due to the reciprocation of the fluid flow path groove, the flow velocity of the oxidant flowing through the fluid flow path groove 15 increases, and as a result, the battery reaction occurs even on the downstream side where the water vapor partial pressure in the oxidant is high. Evaporation and gas diffusion of the moving water that moves from the catalyst electrode (anode electrode) to the catalyst electrode (cathode electrode) together with the generated water and hydrogen ions that accompany it are promoted and liquefied or dropletized. The discharge of generated water and moving water in the porous carbon electrode (cathode electrode) into the oxidizing agent is also promoted. As a result, gas diffusion of the oxidant into the carbon electrode (cathode electrode) is also promoted, a stable battery reaction can be maintained, and the fuel cell output can be stabilized.

【0023】

[Effect of the invention]

As described above, the gas separator according to the present invention has the following effects.

【0024】

(1) Since the moisture is supplemented by the humidified moisture from the upstream part of the adjacent flow path through which the fuel or oxidant flows, which still has sufficient moisture, the electric field quality is sufficiently retained almost uniformly over the entire surface of the electrolyte. It becomes possible to maintain the state, and as a result, it is possible to maintain the conductivity of the electrolyte, that is, to stabilize the output of the fuel cell.

【0025】

(2) Due to the reciprocation of the flow path, the flow velocity of the oxidizing agent flowing through the flow path increases, and in particular, the generated water generated by the battery reaction and the generated water generated by the battery reaction even on the downstream side where the partial pressure of water vapor in the oxidizing agent is high. Evaporation and gas diffusion of moving water that moves from the anode electrode, which is the catalyst electrode, to the cathode electrode together with hydrogen ions into the oxidizing agent is promoted, and liquefied generated water in the porous carbon electrode (cathode electrode) is promoted. And the discharge of moving water into the oxidant is also promoted. As a result, gas diffusion of the oxidant into the carbon electrode (cathode electrode) is also promoted, a stable battery reaction can be maintained, and the fuel cell output can be stabilized.

[Simple explanation of drawings]

[Figure 1]

It is the schematic of the flow path shape of the gas separator of the solid polymer electrolyte fuel cell which concerns on this Example.

[Figure 2]

It is the schematic of the flow path shape of the gas separator of the solid polymer electrolyte fuel cell which concerns on the prior art.

[Fig. 3]

It is a power generation principle diagram of a solid polymer electrolyte fuel cell.

[Explanation of symbols]

8 Separator 9 Fluid introduction hole 10 Fluid discharge hole 11 Inlet side fluid manifold 12 Outlet side fluid manifold 13 Inlet side fluid communication hole 14 Outlet side fluid communication hole 15 Fluid flow channel groove