JPS59217955A - Phosphoric-acid-type fuel cell - Google Patents

Abstract

PURPOSE:To extend the active ranges of both electrodes and improve the utilization rates of catalyst layers by forming an undulation on the surface of each electrode base material opposite to its surface having reaction gas flow paths and installing the catalyst layers along the undulations. CONSTITUTION:An undulation is formed on the surface of a cathode base material 22 opposite to its surface having air flow paths 23. An undulation is also formed on the surface of an anode base material 27 opposite to its surface having fuel flow paths 28. A cathodic catalyst layer 24, an electrolyte material 25 and an anodic catalyst layer 26 are installed along these undulations. Internal reservoirs 29 are installed in one of the base materials 22 and 27. When the internal reservoirs 29 are installed in the concave areas 27b of the anode, anodic catalyst layers 26 are installed only on the convex areas 27a of the anode. Gas separators 1 are installed in the same manner as in the conventional fuel cell. According to such a phosphoric-acid-type fuel cell, gas reaction can be improved by effectively utilizing the catalyst layers 24 and 26, thereby realizing an excellent cell characteristic.

Description

[Detailed Description of the Invention] The present invention relates to a phosphoric acid fuel cell, and more specifically, a unit cell consisting of an air electrode, an electrolyte matrix, and a fuel electrode, and an electrode provided with a reaction gas flow path. The present invention relates to a phosphoric acid fuel cell including a base material and gas separation plates sandwiching the base material.

A conventionally well-known phosphoric acid fuel cell has an electrolyte matrix containing phosphoric acid as an electrolyte placed between a fuel electrode (anode) and an air electrode (cathode) that are arranged opposite each other. Each is operated by supplying fuel gas and air. At this time, the supply groove for supplying the reaction gas can be disposed of in two ways depending on whether it is provided in the gas separation plate or in the electrode base material.The former is generally called the paper type, and the latter is generally called the ribbed electrode type. being called. In particular, the electrode type with a lip can be provided with an internal reservoir, which is a mechanism for controlling the volume of the electrolyte, in the electrode base material, and is attracting attention as being advantageous for long-term stability of the battery.

FIG. 1 shows an anode electrode substrate having a conventional lipped catalyst layer with an internal reservoir and an anode catalyst layer 6 in contact with an electrolyte matrix S disposed in contact with a cathode catalyst layer 1. A fuel flow path g is formed at 7. Further, an internal reservoir 9 is arranged in the anode electrode base material 7.

In such a configuration, fuel and air flow into the cell orthogonally to each other as shown in FIG. That is, in FIG. 2, air is supplied to the air inlet side manifold 10.
The fuel flows from the fuel inlet side manifold 12 to the fuel return side manifold 13, and then to the fuel outlet side manifold /q as shown by the dotted chain line. flow perpendicular to.

The reason why the fuel is returned through the fuel return side manifold/3 is that if the reaction gas is simply crossed at right angles, the reaction gas will be consumed within the single cell, and the air will be the most diluted and the fuel will be the most diluted. This is to prevent desired battery characteristics from being achieved due to non-uniform current distribution within the cell surface due to the formation of the same part as the cell, and by returning the fuel gas, the current distribution is made uniform. It is.

Here, the flow of the reaction gas will be further considered. Third
The figure is a partially enlarged view of the cathode side, showing the air flow path 3.
The air flowing through the cathode electrode substrate passes through the porous cathode electrode base material, reaches the cathode catalyst layer, and reacts. When passing through this cathode electrode substrate, the airflow experiences a fairly large diffusion resistance, which causes a local reduction in current density.
This will reduce battery efficiency. This phenomenon is more noticeable in the lipped electrode type than in the thin paper type. The arrows shown in FIG. 3 indicate the flow of air from the air flow path 3 to the cathode catalyst layer, but compared to the air that passes through the thinnest arrow a of the cathode electrode base material, the arrows that pass through the thickest part of the cathode electrode base material , 5 will experience greater diffusion resistance. Therefore, regarding the entire surface of the cathode catalyst layer, air reacts efficiently in the area directly below the air flow path 3 as shown by arrow a, and diffusion resistance occurs in the area sandwiched between the air flow paths 3 as shown by arrows a and c. This reduces the air utilization rate.

The former active catalyst layer area/S is referred to as an active area, and the latter catalyst layer area/6 that has entered the blind spot is referred to as a blind spot area.

The figure shows the internal reservoir on the anode side? This is an enlarged view of the vicinity. Simply put, the internal reservoir 9 is made by filling the anode electrode base material 7 with a substance that is highly wettable to phosphoric acid, such as silicon carbide powder, and impregnating it with phosphoric acid. No blind area is formed in the anode catalyst layer B near the internal reservoir, and the blind area /6 is directly connected to the electrolyte matrix S. Is this due to the change in the volume of phosphoric acid in the electrolyte (IJ) internal reservoir? This is to control the 9th
As far as the figure shows, the anode catalyst layer 6 has been reduced by half.

The structure of the above ribbed electrode will be explained in more detail with reference to FIG. FIG.
The negative side and the anode side are shown with oppositely oriented slants λ and ox.

As is clear from this figure, a dual active region /7, in which both the cathode and the anode are active regions, and a double blind region /g, in which both the cathode and the anode are blind regions, are generated. Then both active areas/7
In this case, the reaction gas reacts most efficiently, and on the other hand, in the double blind area/g, the reaction gas has the lowest efficiency. Here, the internal reservoir 9 is formed into a circular shape using both blind areas/g.

Both blind areas/g are unique because the reaction gas flow paths are orthogonal to each other, but if the air flow path 3 is
If the fuel flow path g and the fuel flow path g are made to flow in parallel, both blind areas will not occur, but both active areas will also disappear.

Conventional lip-equipped electrode fuel cells had the above-mentioned busy configuration, and had the disadvantage that they had a blind spot area of 20,000 yen compared to the entire planar area of the single cell, which meant that the catalyst layer could not be used effectively. . In addition, although these blind areas were used as internal reservoirs, there was a problem in that these internal reservoirs were localized and did not have a structure that could supply phosphoric acid from the outside.

This invention was developed by focusing on the above-mentioned circumstances, and by creating undulations in units of reaction gas flow paths on the opposite surface of the electrode base material to the direction in which the reaction gas flow paths were formed, and by forming undulations along these undulations. The purpose of this invention is to provide a Schiff 1/62 type fuel tank which expands both active regions and significantly improves the utilization of the catalyst layer by using a structure provided with a catalyst layer.

Furthermore, in accordance with the object of the present invention, a catalyst layer is formed in the peaks of the electrode base material and an internal reservoir is formed in the valleys of the undulating surface of the electrode base material on the side opposite to the surface on which the reaction gas flow path is provided. It is an object of the present invention to provide a phosphoric acid fuel cell in which the active area is expanded to 1/2 of the entire surface of the unit cell plane, the blind areas are completely eliminated, and the battery characteristics are 1 ij J lt-.

Furthermore, it is an object of the present invention to connect the internal reservoirs of 11 to 81 to enable phosphoric acid replenishment from the outside, and to provide a phosphoric acid fuel with an IL internal reservoir structure that is effective for long-term maintenance of the pond. B) No batteries are provided.

An embodiment of the present invention will be described below with reference to the drawings 1-7. FIG. 7 shows a ribbed electrode of this embodiment, in which the cathode 1ti, the pole base, and the surface opposite to the surface on which the air flow path 23 of 2.2 is formed have undulations in units of air flow path 23, that is, seven The air flow path 23 forms undulations. -2a
22b indicates the cathode peak, and 22b indicates the cathode valley. 1° The anode is also placed on the seed base material 27, and on the opposite side to the surface on which the fuel flow path 2g is formed, the cathode peak, 2 cores a, and cathode name/part-1 are formed. Forms undulations having valleys 7b and anode peaks 27a facing each other, and between both undulations, along these undulations, a cathode contact layer, 2 layers, and an electrolyte 7 matrix are formed. , 2b, an anode catalyst layer, and 2B are arranged.

In this example, the internal reservoir J9 is provided in the valley part b, and the anode consolation layer 6 is provided only in the anode peak part .gamma.a. The gas separation plate/is the same as the conventional one.

Next, the action and effect will be explained. Figures g and q show the flow of reaction scum, and in Figure 3, white arrows indicate the flow of air, and black arrows indicate the flow of fuel gas. Air is supplied to the air inlet side internal manifold 3o formed on the gas separation plate/7.
The air flows along the air flow path 23 and is guided to the internal manifold 31 on the air outlet side. The fuel gas is led from the fuel inlet side internal manifold 32 to the fuel outlet side internal manifold 33 through the fuel flow path 2g. 3q is an external reservoir. Looking at this in the plan view of FIG. 9, the /point fA gland indicates the flow of fuel gas, and the two-dot chain line indicates the flow of air.Air flows from the air inlet side manifold 3s to the air outlet side manifold 3s.
6, the fuel gas is on the fuel inlet side mark 4#)'J? , fuel inlet side internal manifold 3λ, fuel outlet side internal manifold 3
3 to the fuel outlet side manifold 3g. 3qa
is the electrolyte supply port of the external reservoir 3da. As shown in the figure, the air flow and the fuel gas flow flow parallel to each other, but there is no blind spot between the two sides as in the conventional case. This point will be explained in more detail.

FIG. 10 is an enlarged view of a part of the cathode side, and the arrows indicate the flow of air from the air flow path 23 to the cathode contact layer W:JQ. It passes through the thinnest part of the electrode base material 2.2. Therefore, a wide active region 39 is obtained.

On the other hand, as shown by the arrow d, the cathode electrode base material j,
The blind area yo passing through the thick portion of No. 2 is approximately 1/3 of the active area 39, which is significantly reduced.

Figure 1 shows an enlarged view of a part of the anode side.
An internal reservoir 29 is provided using the blind area lIo, and the active area 39 is enlarged similarly to the cathode side.

Figure 1 is a plan view showing the cathode side and anode side of the above configuration stacked together, and shows the blind area aO and both active areas 9/
, the blind spot area does not exist at all, and the active area is 4t.
l is approximately // the total area seen on a plane. White arrows indicate the air flow, and black arrows indicate the direction of the fuel gas flow.

In this way, when the above embodiment is used, both active regions are approximately doubled compared to the conventional device, and the efficiency of gas reaction is improved accordingly. In addition, by providing the internal reservoir in the blind area on the anode side, the internal reservoir is not localized as in the conventional case but is arranged in a straight line. The internal reservoir can be communicated and phosphoric acid can be supplied from the outside, which greatly improves the function of the internal reservoir.

In the above embodiment, the internal reservoir is formed on the anode side, but it may also be formed using the blind area on the cathode side (or furthermore, it may be provided on both the anode and the cathode.

Further, the internal manifold does not necessarily need to be provided on the gas separation plate, but may be provided on the electrode base material side (the same effect can be achieved. The same applies to the external reservoir.

As is clear from the above description, the present invention effectively utilizes the catalyst layer to improve the gas reaction and realize excellent battery characteristics, and also has exceptional effects such as improving the function of the internal reservoir. It is something that you have.

[Brief explanation of drawings]

Figure 7 is a side sectional view of the main part of the conventional model, Figure 2 is the same (a plan view showing the flow of reaction gas in the conventional model, and Figure 3 is the same (an enlarged front sectional view of the cathode of the conventional model, Figure 7 is the same). are the same (enlarged side sectional view of the conventional anode, Figure S, Figure 6).
The figures are the same (a plan view showing the active area and blind area of the conventional device, and FIG. 7 is a side sectional view of the main part of an embodiment of the present invention).
Figure 3. FIG. 9 is a front sectional view and a plan view showing the flow of the reaction gas, FIG. io and FIG. FIG. 3 is a plan view showing an active area and a blind area. /... Gas separation plate 1.2.2... Cathode electrode base material, 2
3... Air flow path 5.21I... Cathode catalyst layer 1.2... Electrolyte matrix 1.26... Anode catalyst layer, 2
7. Anode electrode base material, 2g.. Fuel flow path 1.2q.
・Internal reservoir, 3θ・・Air inlet side internal manifold,
31... Air outlet side manifold, 3.2... Fuel population side internal manifold, 33... Fuel outlet side internal manifold,
3Hiroshi...External reservoir, 3S...Air intake white side manifold, 36...Air outlet side manifold, 37...Fuel inlet side manifold, 3g...Fuel outlet side manifold, 39...
Active area, Hiro θ...Blind area, F/...Both active area. In each figure, the same reference numerals indicate the same or corresponding parts. Agent Masu Oiwa Yusaki 10th figure fever 11th figure

Claims (1)

[Scope of Claims] (1) An electrolyte matrix, a cathode electrode base material having a cand catalyst layer and an air passage, an anode electrode base material having a seven-node catalyst layer and a fuel passage, and phosphoric acid is supplied. an internal reservoir formed in either the cathode electrode base material or the anode electrode base material, and
In a phosphoric acid fuel cell comprising a gas separation plate disposed outside each of the cathode electrode base material and the anode electrode base material, the gas separation plate disposed on the outside of each of the cathode electrode base material and the anode electrode base material, A phosphoric acid fuel cell characterized in that the air flow path and the fuel flow path each have undulations formed on a surface opposite to a surface where the air flow path and the fuel flow path are formed. (2) The phosphoric acid fuel cell according to claim 7, wherein a canned catalyst layer and an internal reservoir are formed in the undulating peaks and valleys of the cathode electrode base material, respectively. (3) The phosphoric acid fuel cell according to claim 1, wherein an anode catalyst layer and an internal reservoir are formed in the undulating peaks and valleys of the anode electrode base material, respectively. <4') Claim 2 or 3, in which the internal reservoir communicates with an external reservoir provided in the gas separation plate.
The phosphoric acid fuel cell described in . (3) The phosphoric acid fuel cell according to claim 7, wherein the air flow path and the fuel flow path communicate with internal manifolds provided on the cathode electrode base material and the anode electrode base material, respectively. (6) The phosphoric acid according to claim 1, wherein the air flow path and the fuel flow path communicate with internal manifolds provided in the gas separation plates on the cathode electrode base material side and the anode electrode base material side, respectively. shaped fuel cell.