JPH06349511A - Fuel cell - Google Patents

Abstract

PURPOSE:To provide a high-power and large-capacity fuel cell. CONSTITUTION:A fuel cell mainframe has single cells isolated in two lines in longitudinal and lateral directions to be planely arrayed in such a structure that these single cells and interconnectors 20-22 are in layers. Gas distributing plates 40, 41 are arranged at the upper and lower parts of the fuel cell mainframe. An oxygen gas supply groove 42 and an oxygen gas exhaust groove 43 are provided on the lower face of the gas distributing plate 40, both 42, 43 having the ends in branch structures. A fuel gas supply groove 44 and a fuel gas exhaust groove 45 are provided on the upper face of the gas distributing plate 41, these grooves having the ends in branch structures.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphate type, a molten carbonate type, a solid electrolyte type fuel cell and the like.

[0002]

2. Description of the Related Art Generally, in a fuel cell of a phosphate type, a molten carbonate type, a solid electrolyte type, etc., a single cell made of an electrolyte having an anode electrode and a cathode electrode respectively provided on the front and back surfaces and an interconnector are stacked. There are different structures.
In this type of fuel cell, it is necessary to make the electrolyte as thin as possible in order to achieve high output. Conversely, in order to increase the capacity, it is necessary to increase the area of the single cell, and the larger the area of the single cell, the greater the stress applied to the single cell. You have to increase your strength. Therefore, it has been difficult to increase the output and the capacity of the fuel cell.

As a countermeasure against this, a structure has been proposed in which a plurality of single cells are arranged side by side between interconnectors.
In this case, the flow path of the fuel gas and the oxidizing gas supplied to the fuel cell becomes a problem. That is, when the flow path of the fuel gas or the oxidizing gas becomes long, the gas consumption progresses in the process from the gas supply port to the discharge port, and the concentration of the gas becomes lower toward the discharge port. If the gas concentration distribution becomes uneven between a plurality of single cells arranged side by side, unevenness in power generation causes temperature unevenness inside the single cells, and thermal stress causes cracks or cracks in the single cells. I have a concern. In addition, the density of the current generated in the fuel cell is uneven, which causes deterioration of the anode electrode and the cathode electrode.

Therefore, an object of the present invention is to provide a fuel cell having a structure in which a plurality of single cells are arranged side by side between interconnectors and the gas concentration distribution unevenness is small.

[0005]

In order to solve the above problems, the fuel cell according to the present invention comprises: (a) an electrolyte and a rectangular electrode composed of an anode electrode and a cathode electrode provided on the front and back surfaces of the electrolyte, respectively. A laminated structure in which a unit cell having a shape and an interconnector are stacked, and (b) the rectangular unit cells are arranged side by side in a two-dimensional array in the vertical and horizontal directions between the interconnectors. (C) The gas flow holes are arranged in a square shape in the interconnector, and a gas manifold is provided around each of the rectangular unit cells, (d)
It is characterized in that a gas collecting and distributing section for supplying gas to the gas manifold and having a gas flow passage having a branched structure with branched ends is provided at an end of the laminated structure. Approximately half of the gas distribution holes provided in the interconnector are used as gas supply paths, and the remaining gas distribution holes are used as gas discharge paths.

Further, the gas flow passage has two passages toward the tip.
It is preferable that the units are sequentially divided by a unit of a multiplier of, that is, a unit of two divisions. With this structure, the gas flow becomes more uniform. In the above structure, the gas (fuel gas or oxidizing gas) is supplied to the anode electrode or the cathode electrode from the gas flow hole used as the supply path. The supplied gas causes an electrode reaction via the electrolyte. The gas after the reaction is discharged through a gas flow hole used as a discharge passage. Gas is uniformly supplied to each of the gas manifolds, each of which partially includes a gas flow hole, from a gas collector / deliverer having a gas flow passage having a branched structure with branched ends. Since each gas manifold is located around each rectangular unit cell juxtaposed between the interconnectors, the gas is evenly supplied to and discharged from the rectangular unit cell. Therefore, the situation where the gas concentration distribution becomes uneven does not occur.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the fuel cell according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows the structure of a solid oxide fuel cell body. The solid electrolyte 1 has a rectangular shape, and as a material thereof, ZrO ₂ or the like which is stable with 8 mol% of Y ₂ O ₃ added is used. The cathode electrode 2 is formed on the upper surface of the solid electrolyte 1, and the anode electrode 3 is formed on the lower surface of the solid electrolyte 1. The cathode electrode 2 is made of a perovskite type oxide conductive material such as (La, Sr) MnO ₃ and the anode electrode 3 is made of Ni.ZrO ₂ cermet. The solid electrolyte 1, the cathode electrode 2, and the anode electrode 3 are cosintered (fired at the same time) after stacking the respective green sheet-shaped raw materials and press-bonding them.
As a result, the solid electrolyte 1 having the cathode 2 and the anode 3 provided on the upper and lower surfaces, that is, the rectangular single cell 4 is obtained. The unit cells 4 are arranged in a plane so as to be separated from each other in two rows in the vertical and horizontal directions.

A current collector 5 is provided on the upper surface of each unit cell 4.
Are arranged in contact with the cathode electrode 2. The current collector 5 is a porous body made of (La, Sr) MnO ₃ or the like. On the lower surface of each unit cell 4, a current collector 6 is arranged in contact with the anode electrode 3. The current collector 6 is made of Ni mesh or the like. The gasket 10 is in the shape of a square, and 16 holes 10a for supplying oxidizing gas are provided in the central pillar portion in the left-right direction, and 8 holes 10b for discharging oxidizing gas are provided on the front side and the back side of the outer frame. It is provided. The gasket 10 is arranged on the upper surface of the unit cell 4 with the current collectors 5 inserted into the four holes 10c.

Similarly, the gasket 11 is in the shape of a square, and the oxidizing gas supply hole 11a is formed in the central column portion in the left-right direction.
16 are provided, 16 fuel gas supply holes 11b are provided in the central pillar portion in the front-rear direction, and 8 oxidizing gas discharge holes 11c are provided on the front side and the rear side of the outer frame portion. Eight fuel gas discharge holes 11d are provided on each of the right side and the left side. The gasket 11 is a unit cell 4 with the current collectors 5 (or 6) inserted into the four holes 11e.
Is placed on the upper surface (or lower surface) of.

The gasket 12 (see FIGS. 2 and 3) is in the shape of a square, and 16 fuel gas supply holes 12a are provided in the central column portion in the front-rear direction, and fuel is provided on the left and right sides of the outer frame portion. Eight gas discharge holes 12b are provided. The gasket 12 is arranged on the lower surface of the unit cell 4 with the current collectors 6 inserted into the four holes 12c. The gaskets 10 and 11, the gaskets 11 and 11, or the gaskets 11 and 12 are joined together at their edges to shield the oxidizing gas and the fuel gas from the outside air. These gaskets 10 to 12 are made of a composite material of ceramic fiber and glass.

The interconnector 20 is provided with 16 holes 20a for supplying oxidizing gas in the left and right direction of the central portion, and 8 holes 20b for discharging oxidizing gas are provided at the front and rear edges, respectively. The lower surface of the interconnector 20 has a plurality of grooves 20c.
(See FIGS. 2 and 3) are provided at a predetermined interval,
The oxidizing gas 30 spreads to the cathode 2 by the groove 20c. The interconnector 20 is arranged above the fuel cell.

The interconnector 21 has 16 holes 21a for supplying an oxidizing gas in the left and right direction at the center and 16 holes 21b for supplying a fuel gas in the front and rear direction at the center, and is provided at the front and rear edges. Eight holes 21c for discharging the oxidizing gas are provided respectively, and the holes 21c for discharging the fuel gas are further provided on the right and left edges.
Eight d's are provided. A plurality of grooves 21e and 21f (see FIG. 2) are formed on the upper surface and the lower surface of the interconnector 21, respectively.
And FIG. 3) are provided at predetermined intervals, and the groove 21
The fuel gas 31 spreads to the anode 3 by e,
Air 30 reaches the cathode 2 by the groove 21f.

Interconnector 22 (see FIGS. 2 and 3)
Has 16 holes 22a for supplying fuel gas in the front-rear direction of the central part, and 8 holes 22b for discharging fuel gas at the right and left edges, respectively. A plurality of grooves 22c are provided on the upper surface of the interconnector 22 at predetermined intervals, and the fuel gas 31 spreads to the anode electrode 3 by the grooves 22c. The interconnector 22 is arranged below the fuel cell. As a material for the interconnectors 20 to 22, a heat resistant alloy such as a nickel chromium alloy is used.

The above single cell 4, current collectors 5, 6, gaskets 10-12, and interconnectors 20-22 are stacked to form a solid oxide fuel cell. The oxidant gas supply manifold includes the holes 20a, 10a, 11a, 21a and the unit cell 4.
The oxidant gas exhaust manifold is formed by communicating the gaps with each other, and the oxidant gas exhaust manifolds have holes 20b, 10b, 11c, 21c.
Are formed by communicating with each other, and the manifold for fuel gas supply has holes 22a, 12a, 11b, 21b and unit cell 4
The fuel gas exhaust manifolds are formed by communicating the gaps between them, and the fuel gas exhaust manifolds have holes 22b, 12b, 11d, 21d.
Are formed by communicating with each other.

Next, the operation of the fuel cell body will be described with reference to FIGS. The fuel gas 31 is guided to the anode electrode 3 of each unit cell 4 from the fuel gas supply hole 22a of the interconnector 22 through the fuel gas supply manifold. Similarly, the oxidizing gas 30 is guided from the oxidizing gas supply hole 20a of the interconnector 20 to the cathode 2 of each single cell 4 through the oxidizing gas supply manifold. The inside of the fuel cell is maintained at a high temperature (about 1000 ° C.), and the oxidizing gas 30 supplied to the cathode 2 and the fuel gas 31 supplied to the anode 3 cause an electrode reaction through the solid electrolyte 1. A current flows in the thickness direction of the unit cell 4. The fuel gas 31 after the reaction passes through the fuel gas discharge manifold and is discharged from the fuel gas discharge hole 22b of the interconnector 22. Similarly, the oxidizing gas 30 after the reaction passes through the oxidizing gas discharging manifold and is discharged from the oxidizing gas discharging hole 20b of the interconnector 20. Since the oxidant gas supply manifold and the fuel gas supply manifold are located around each of the unit cells 4 arranged side by side in a plane between the interconnectors, the oxidant gas 30 and the fuel gas 31 are separated from each other. It is evenly supplied to the cells 4.

Next, as shown in FIG. 4, gas collecting and distributing plates 40 and 41 are arranged above and below the fuel cell body. As shown in FIG. 5, the gas distribution plate 41 is provided with a fuel gas supply groove 44 and a fuel gas discharge groove 45 on the upper surface. The fuel gas supply groove 44 and the fuel gas discharge groove 45 have a fuel gas supply opening 44b and a fuel gas opening 4 at one end respectively.
5b is provided. The other end is branched and has a branched structure, and the respective end portions 44a and 45a are provided at positions communicating with the fuel gas supply hole 22a and the fuel gas discharge hole 22b of the interconnector 22, respectively. .

Similarly, the gas collecting and distributing plate 40 is provided with an oxidizing gas supply groove 42 and an oxidizing gas discharge groove 43 on the lower surface.
The oxidizing gas supply groove 42 and the oxidizing gas discharge groove 43 are provided with an oxidizing gas supply port 42b and an oxidizing gas discharge port 43b at one end respectively. The other end is branched and has a branched structure, and the respective end portions 42a and 43a are provided at positions communicating with the oxidizing gas supply hole 20a and the oxidizing gas discharge hole 20b of the interconnector 20. As a material of the gas collecting and distributing plates 40 and 41, a heat resistant alloy such as a nickel chromium alloy is used.

In the fuel cell having the above structure, the oxidizing gas 30 flowing into the oxidizing gas supply port 42b is provided in the interconnector 20 through the oxidizing gas supply groove 42 having a branched structure with branched ends. It is uniformly supplied to each of the oxidizing gas supply holes 20a. Similarly, the fuel gas 31 that has flowed into the fuel gas supply port 44b passes through the fuel gas supply groove 44 having a branched structure with the end portion branched, and then the fuel gas supply hole 22a provided in the interconnector 22. Is evenly supplied to each. Further, since the oxidizing gas discharging manifold and the fuel gas discharging manifold are located around each of the unit cells 4 arranged side by side in a plane between the interconnectors, the oxidizing gas after reaction 30
The fuel gas 31 is evenly discharged to these unit cells 4. As a result, since the oxidizing gas 30 and the fuel gas 31 are evenly supplied to and discharged from the single cell 4,
A solid oxide fuel cell having a small gas concentration distribution unevenness can be obtained. Further, the gas collecting and distributing plates 40 and 41 have a function of preheating the supplied oxidizing gas and fuel gas before introducing them into the fuel cell main body, and cool the fuel cell main body to protect the fuel cell from overheating. Have a function.

FIG. 6 shows the power generation characteristic evaluation results when the solid oxide fuel cell thus obtained was operated at 1000 ° C.
(Solid line 51). Here, the unit cell 4 has a side of 12c
The squares of m were used, and super-humid hydrogen gas was used as the fuel gas and air was used as the oxidizing gas. Interconnector 2
As materials for 0 to 22, Inconel 600 (74% nickel, 15% chromium, 8 iron), which has excellent high temperature oxidation resistance.
%)It was used. For comparison, FIG. 6 shows an evaluation result (dashed line 52) of a solid oxide fuel cell having a structure in which only one unit cell is arranged between interconnectors, and a solid oxide fuel cell without a gas collecting plate. Evaluation result (dotted line 53)
And are also described.

As shown in FIG. 6, the terminal voltage in the open circuit state (the terminal current is 0 [A]) was 1.04 [V], which is almost the theoretical value. On the other hand, in the fuel cell of this example, the amount of decrease in the terminal voltage is small even if the terminal current increases. However, in the fuel cell of the comparative example, the terminal voltage rapidly decreases as the terminal current increases. In particular, it is recognized that the power generation amount of the fuel cell of this example is about four times that of the solid oxide fuel cell having a structure in which only one unit cell is arranged between the interconnectors. In addition, the gas distribution plate 40,
When 41 is not provided, it is insufficient to uniformly supply the oxidizing gas and the fuel gas to the oxidizing gas supply manifold and the fuel gas supply manifold, so that the suppression of the gas concentration distribution unevenness may be insufficient. Is recognized.

The fuel cell according to the present invention is not limited to the above embodiment, but can be variously modified within the scope of the gist thereof. Although the solid oxide fuel cell has been described in the above embodiment, it may be a phosphate type or molten carbonate type fuel cell. Further, the gas flow passage of the gas collecting and distributing plate does not necessarily have to be a groove provided on the surface of the gas collecting and distributing plate. For example, the gas collecting and distributing plate may be horizontally divided into two, grooves may be formed on the respective dividing surfaces, and then the dividing surfaces may be joined to each other to provide a tubular gas flow passage inside the gas collecting and distributing plate.

[0022]

As is apparent from the above description, according to the present invention, each gas manifold is provided with a gas flow passage having a branch-like structure with branched ends so that a uniform distribution can be obtained from the gas collecting and distributing portion. The gas manifolds are located around each rectangular unit cell juxtaposed between the interconnectors, so that the gas is evenly supplied to and discharged from each unit cell. It is possible to suppress uneven density distribution. As a result, it is possible to obtain a high-output and large-capacity fuel cell in which temperature unevenness is unlikely to occur inside the unit cell, and the unit cell is not cracked or cracked due to thermal stress. Further, the density of the current generated in the fuel cell becomes uniform, and there is no concern that the anode and cathode will deteriorate.

Further, by providing the gas collecting and distributing section at the end of the fuel cell body, the effect of preheating the supply gas and the effect of cooling the fuel cell body can be obtained, and the size of the fuel cell can be reduced.

[Brief description of drawings]

FIG. 1 shows an embodiment of a fuel cell according to the present invention, and is an assembled perspective view of a fuel cell main body.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is an assembled perspective view of the fuel cell main body and the gas distribution plate shown in FIG.

FIG. 5 is a plan view of the gas distribution plate shown in FIG.

6 is a graph showing power generation characteristics of the fuel cell shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Solid electrolyte 2 ... Cathode electrode 3 ... Anode electrode 4 ... Single cell 21 ... Interconnector 21a ... Oxidizing gas supply hole (gas distribution hole) 21b ... Fuel gas supply hole (gas distribution hole) 21c ... Oxidation gas Discharge hole (gas distribution hole) 21d ... Fuel gas discharge hole (gas distribution hole) 40, 41 ... Gas distribution plate 42 ... Oxidizing gas supply groove 43 ... Oxidizing gas discharge groove 44 ... Fuel gas supply groove 45 ... Fuel Gas exhaust groove

Claims (2)

[Claims] 1. A laminate structure in which an electrolyte and a rectangular single cell composed of an anode electrode and a cathode electrode respectively provided on the front and back surfaces of the electrolyte and an interconnector are stacked, and between the interconnectors, The rectangular unit cells are arranged side by side so as to be separated into two rows each in the vertical and horizontal directions, and gas passage holes are arranged in a square shape in the interconnector, and each of the rectangular unit cells is arranged. A gas manifold is provided around the gas manifold, and a gas collector / distributor for supplying gas to the gas manifold is provided at an end of the laminated structure, the gas collector having a branched gas flow passage having a branched end. Is a fuel cell. 2. The fuel cell according to claim 1, wherein the gas flow passage is divided into two toward the tip.