JPS63313472A - Free electrolyte fuel cell - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the structure of an electrolyte chamber defined between a pair of opposing electrodes in a free electrolyte fuel cell, particularly an alkaline fuel cell.

[Conventional technology]

A single cell, which is the basic structure of a free electrolyte fuel cell, such as an alkaline fuel cell, has a structure as shown in an exploded perspective view of FIG. In the figure, 1 is a fuel electrode, 2 is an oxidizer electrode, and the fuel electrode 1 has a porous fuel electrode membrane 1a,
On the other hand, the oxidizer electrode 2 consists of a porous oxidant electrode film 2a and a porous carbon paper 1b which is an electrode base material bound together. It consists of paper 2b. The fuel electrode 1 and the oxidizer electrode 2 form a pair of electrodes, and the fuel electrode 1 and the oxidizer electrode 2 are fitted into a gas-impermeable frame-shaped cell frame 3 and face each other through a central hole space. are doing. This hole space is an electrolyte chamber 4 through which an alkaline aqueous solution as an electrolyte flows.
A liquid chamber spacer 5 is inserted into the electrolyte chamber 4 to maintain a distance between the fuel electrode 1 and the oxidizer electrode 2.

The chestnut fluid chamber spacer 5 is made of R resin, and is shown in the plan view in FIGS. 3 to 6, the AA arrow view, the BB sectional view, the C-C sectional view, and the partial arrow view in FIG. As shown, it is made of a corrugated sheet with continuous peaks 6 and valleys 7 having a rectangular cross section, and the peaks 6
A plurality of rectangular holes 6a are provided in the trough portion 7, and a plurality of rectangular holes 7a are provided in the valley portion 7, and the holes 6a and the holes 7a are arranged alternately in a checkered pattern. And the liquid chamber spacer 5 has a mountain tI6.
The upper surface 6b of 6 is placed in contact with the fuel electrode 1, and the lower surface 7b of the trough 7 is placed in contact with the oxidizer electrode 2.The alkaline aqueous solution flowing into the electrolyte chamber 4 is supplied to the fuel electrode 1 from the hole 6a and from the hole 7a. It is in contact with the oxidizer electrode 2.

Returning to FIG. 2, gas-impermeable partition plates 9 are arranged on both sides of the fuel electrode 1 and oxidizer electrode 2 via O-rings inserted into O-rings a8 provided in the cell frame 3. , the partition plate 9 has a plurality of rows of protrusions 9a on both plate surfaces, and between the adjacent protrusions 9a on one plate surface is a flow path for supplying fuel gas to the fuel electrode l, and on the other plate surface. A flow path for supplying oxidizing gas to the oxidizing electrode 2 is formed between adjacent protrusions 9a.

The cell frame 3 and the upper and lower parts of the partition plate 9 are provided with fuel gas supply manifold holes 10 for supplying fuel gas from the outside to the fuel gas flow path formed in the partition plate 9, and an unreacted fuel gas that flows through the fuel gas flow path. It has a fuel gas discharge manifold hole 11 for discharging the fuel gas, and an oxidant gas supply manifold hole 12 and an oxidant gas flow path for supplying the oxidant gas to the oxidant gas flow path formed in the partition plate 9. An oxidant gas discharge manifold hole 13 through which unreacted oxidant gas flows is provided. Further, a supply manifold hole 14 for supplying an alkaline aqueous solution to the electrolyte chamber 4 is provided at the lower part of the cell frame 3 and the partition plate 9, and a discharge manifold hole 15 for discharging the alkaline aqueous solution flowing through the electrolyte chamber 4 is provided at the upper part. ing.

In an alkaline fuel cell, a plurality of the above single cells are stacked to form a cell stack, and the electric power required by the load is extracted from the cell stack.

The alkaline aqueous solution flows through the electrolyte chamber 4 via the corrugated liquid chamber spacer 5 and is discharged from the discharge manifold hole 15 for circulation. Then, fuel gas is supplied from the manifold hole 10 to the fuel electrode 1 via the fuel flow path of the partition plate 9, and oxidant gas is supplied from the manifold hole 12 to the oxidant electrode 2 via the oxidant gas flow path of the partition plate 9. The alkaline aqueous solution from the electrolyte chamber 4, the fuel gas, and the oxidizing gas react electrochemically with the fuel electrode membrane 1a of the fuel electrode 1 and the oxidizing agent electrode membrane 2a of the oxidizing agent electrode 2, respectively, to generate electricity. . At this time, the pressure of the fuel gas in the partition plate 9 and the pressure of the fuel gas and oxidant gas flowing in the oxidizer flow path is higher than the pressure of the alkaline aqueous solution in the electrolyte chamber (
are doing. Note that fuel gas and oxidant gas that do not contribute to the electrochemical reaction are discharged to the outside through discharge manifold holes 11 and 13, respectively.

[Problem that the invention seeks to solve]

The liquid chamber spacer 5 inserted into the electrolyte chamber 4 has peaks 6 and valleys 7 whose surfaces 5a and 7a are in contact with the fuel electrode 1 and the oxidizer electrode 2 to maintain the distance between them. The alkaline aqueous solution comes into contact with the fuel electrode 1 and the oxidizer electrode 2 at the areas of the holes 6a and 7a of the liquid chamber spacer 5, respectively. Therefore, the effective reaction area of the electrode decreases,
In order to obtain a reaction area effective for obtaining the required amount of electricity, it is necessary to increase the electrode surface area, which has the disadvantage that the fuel cell becomes larger and heavier. Furthermore, since the pressure of the fuel gas and oxidant gas flowing through the fuel gas flow path and the oxidant gas flow path of the partition plate 9, respectively, is higher than the pressure of the alkaline aqueous solution in the electrolyte chamber, the pressure difference causes the fuel electrode film and the oxidizer electrode film to Another drawback is that it easily peels off from the base material, carbon paper.

An object of the present invention is to increase the effective reaction area for electrochemical reactions even if the area of the electrode with which the electrolyte comes into direct contact is limited by the liquid chamber spacer inserted in the electrolyte chamber, and to increase the An object of the present invention is to provide a liquid chamber structure of an electrolyte chamber of a free electrolyte fuel cell that can prevent separation of a fuel electrode film of an electrode and an oxidant electrode film of an oxidizer electrode.

[Means for solving problems]

In order to solve the above problems, the present invention provides a free electrolyte fuel cell having an electrolyte chamber defined by interposing a liquid chamber spacer that locally contacts the opposing surfaces of a pair of electrodes. , a porous membrane is inserted between the electrode and the spacer.

[Effect]

Since a porous membrane is inserted between the electrode and the liquid chamber spacer, the electrolyte permeates through the porous membrane even in the areas where the liquid chamber spacer locally contacts the opposing surfaces of the pair of electrodes, and the battery Since the reaction occurs, the effective reaction area for the battery reaction increases.

In addition, the osmotic pressure caused by the penetration of electrolyte into the porous membrane is
Since it counteracts the pressure of the reaction gas, the porous membrane is a BF2 layer (bubble pressure barrier) that maintains the pressure of the reaction gas.
form.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a partial sectional view showing the structure of an electrolyte chamber of an alkaline fuel cell as a free electrolyte fuel cell according to an embodiment of the present invention. In FIG. 1, parts that are the same as those in the conventional example shown in FIGS. 2 to 7 are given the same reference numerals, and their explanations will be omitted.

In FIG. 1, a fuel electrode 1 consists of a porous fuel electrode membrane 1a and a carbon paper 1b as an electrode base material, while an oxidizer electrode 2 consists of a porous oxidizer electrode membrane 2a and a carbon paper as an electrode base material. 2b, the porous membrane according to the present invention, that is, the membrane 18 with a high porosity, is made of, for example, a nickel sintered membrane, and is formed between the liquid chamber spacer 5, the fuel electrode membrane 1a, and the oxidizer electrode 2a. is inserted into the BF2 layer (
bubble pressure barrier). Note that the peaks 6 and back surfaces 6b and 7b of the valleys 7 of the liquid chamber spacer 5 are in contact with the membrane 18, respectively, and the electrolyte is brought into direct contact with the membrane 18 through the holes 6a and 7a.

With this configuration, the alkaline aqueous solution that is the electrolyte in the electrolyte chamber 4 permeates through the porous membrane 18 and into the fuel electrode membrane 1a and oxidizer membrane 2a, respectively. For this reason, the hole 6a
The alkaline aqueous solution permeates into areas other than the area of the fuel electrode membrane 1a and the oxidizer electrode membrane 2a with which the alkaline aqueous solution is in direct contact via Therefore, the effective reaction area for electrochemical reactions becomes larger.

In addition, the BF2 layer counteracts the pressure of the fuel gas and oxidant gas that permeate the carbon papers 1b and 2b due to the osmotic pressure generated when the electrolyte permeates into the pores, so the fuel electrode membrane 1a
and oxidizing agent electrode film 2a from being peeled off from carbon papers 1b and 2b, respectively.

〔Effect of the invention〕

As is clear from the above explanation, by inserting a porous membrane between the electrode and the liquid chamber spacer inserted into the electrolyte chamber, the electrolyte permeates through the membrane and comes into contact with the electrode. The liquid chamber spacer makes the reaction area for electrochemical reactions larger than the area where the electrolyte directly contacts the electrodes, making it possible to downsize the fuel cell.Also, the osmotic pressure of the electrolyte penetrating the porous membrane is Since this pressure is maintained by counteracting the pressure of the fuel gas and oxidant gas, which have a higher pressure than the electrolyte in the electrolyte chamber, the fuel electrode membrane and oxidant electrode membrane that constitute the fuel and oxidizer electrodes are used as electrode base materials. It can prevent it from peeling off.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view showing the structure of the electrolyte chamber of a free electrolyte fuel cell according to an embodiment of the present invention, and FIG. 2 is a single cell of a free electrolyte fuel cell with a conventional electrolyte chamber structure. Figure 3 is a plan view of the liquid chamber spacer in Figure 2, Figure 4 is an exploded perspective view of
The figure is a sectional view taken along the line A-A in Fig. 3, Fig. 5 is a sectional view taken along B-B in Fig. 3, Fig. 6 is a sectional view taken along C-C in Fig. 3, and Fig. 7 is a sectional view taken along line C-C in Fig. 2. FIG. 3 is a partial perspective view of a chamber spacer. 1 fuel electrode, 2-oxidizer electrode, 4-electrolyte chamber, 5-liquid chamber spacer, 18-porous membrane. '$1 Figure 7th Ward

Claims (1)

[Claims] 1) In a free electrolyte fuel cell having an electrolyte chamber defined by interposing a liquid chamber spacer that locally contacts opposing surfaces of a pair of electrodes, a porous material is provided between the electrodes and the spacer. A free electrolyte fuel cell characterized by having a membrane inserted therein.