JPH0646572B2 - Fuel cell - Google Patents

Description

TECHNICAL FIELD The present invention relates to a fuel cell used in the energy sector for directly converting chemical energy of a fuel into electric energy.

[Prior Art] In a fuel cell, an electrolyte plate is sandwiched by an oxygen electrode and a fuel electrode from both sides, and by supplying an oxidizing gas and a fuel gas to each electrode, a potential difference is generated between the oxygen electrode and the fuel electrode. The unit configured to generate power is laminated in a plurality of layers via a separator.

Conventionally, such a fuel cell is divided into a cross-flow type, a counter-flow type, and a parallel-flow type fuel cell depending on the flow types of an oxidizing gas that is supplied to the oxygen electrode side across the electrolyte plate and a fuel gas that is supplied to the fuel electrode side. It was being done.

As shown in FIG. 6, the cross-flow fuel cell has a structure in which units formed by sandwiching an electrolyte plate 1 from both upper and lower surfaces by an oxygen electrode 2 and a fuel electrode 3 are stacked with a separator 4 in between. The gas passage 5 on the lower surface of each separator 4 is formed so that the oxidizing gas OG supplied to the electrode 2 side is in the same direction in each layer, and the unillustrated oxidizing gas is formed on one side of the peripheral portion that is one end side of the gas passage 5. Only the gas supply channel hole,
Further, only the oxidant gas exhaust flow passage hole (not shown) is provided on the other side, and the fuel gas FG supplied to the fuel electrode 3 side of each layer is
Each of the separators 4 is so arranged as to flow in the same direction in each layer and in a direction orthogonal to the flow direction of the oxidizing gas OG in each layer.
The gas passage 6 on the upper surface of the
The fuel gas supply passage hole (not shown) is provided only on one side of the peripheral portion which is one end side of the fuel cell, and the fuel gas discharge passage hole (not shown) is provided on the other side. It is designed to flow at right angles.

FIG. 8 is a diagram in which the above-described cross flow type is applied to an external manifold system. When one manifold 7 is attached to each of four side surfaces and the oxidizing gas supply pipe 8 is connected to one of the manifolds 7 facing each other. The oxidizing gas exhaust pipe 9 is connected to the other manifold 7, the fuel gas supply pipe 10 is connected to one of the different manifolds 7 and the fuel gas exhaust pipe 11 is connected to the other manifold 7 facing the other manifold 7. The gas flow is realized.

[Problems to be Solved by the Invention] However, in the case of a cross flow type fuel cell, as shown in FIG. 7 (A), for example, as shown in FIG. There is a large temperature gradient near the exit (B in Fig. 7), and as a result, as shown in Fig. 7 (B).
The current density also has a large gradient with a maximum value at the oxidizing gas outlet. Due to this, in the cross flow type, the composition ratio of the oxidizing gas and the fuel gas cannot be made uniform on the entire plane of the electrolyte plate,
As a result, the temperature distribution of the electrolyte plate cannot be made uniform, and the power generation density cannot be made uniform. Moreover, since the oxidizing gas and the fuel gas in each layer are configured to be a parallel flow that flows only in the same direction, the above temperature distribution and current density distribution are superimposed as they are, and the temperature distribution in the plane becomes even worse. As a result, a large thermal stress is generated in the electrolyte, the electrode, and the separator, and there is a problem that the performance, life, reliability, etc. of the fuel cell are lacking. Further, when the cross-flow type fuel cell is of the external manifold type, it is not necessary to open gas passage holes in the electrolyte plate 1, but sealing is difficult. Further, making the cross-flow fuel cell into an internal manifold type is
There is a large difference in the flow rate of the seed gas, and when the gas with the higher flow rate is passed through the internal manifold, the flow path must be enlarged, which makes distribution difficult.

Therefore, the present invention provides, as factors that determine fuel cell performance,
Focusing on the temperature of the electrolyte plate and the temperature distribution of the fuel gas and the oxidizing gas that flow across the electrolyte plate, the conventional cross-flow fuel cell appears by changing the flow type of the oxidizing gas and the fuel gas. The existing temperature gradient and current density gradient are dispersed to relax the gradient and maximum value, the effective area of the electrolyte plate is increased, and a large amount of gas having a large flow rate is allowed to easily flow. .

[Means for Solving the Problems] In the present invention, first separators are alternately laminated between a plurality of single cells in which an oxygen electrode 2 is arranged on one surface of an electrolyte plate 1 and a fuel electrode 3 is arranged on the other surface. 4a and the second separator 4b, the first
Of the separator 4a and the second separator 4b, which are formed on the surface of the fuel electrode on the fuel electrode side and extend from the vicinity of one end to the vicinity of the other end, and the first separator 4a and the second separator 4b.
A concave oxidant gas passage 5 formed on the oxygen electrode side surface and extending in a direction substantially orthogonal to the fuel gas passage 6, each electrolyte plate 1, the first separator 4a, and the second separator 4b.
Located on one end side of each of the first separator 4a and the second separator 4b and the convex portion 25 formed on the peripheral portion of the surface on the fuel electrode side of each of the first separator 4a and the peripheral portion of the fuel electrode 3 forming the unit cell. As described above, the fuel gas supply passage holes 26 and the fuel gas discharge passage holes 27, which are alternately formed in the convex portion 25, and the respective first separators 4a,
The convex portion is located on the other end side of the second separator 4b.
The fuel gas supply flow passage holes 28 and the fuel gas discharge flow passage holes 29 alternately formed in 25, and the fuel gas supply flow to one end side of the fuel electrode 3, the electrolyte plate 1, and the oxygen electrode 2 which constitute each unit cell. Roadway 26
In addition, the fuel gas supply passage hole 12 and the fuel gas discharge passage hole 13 which are alternately formed so as to communicate with the fuel gas discharge passage hole 27, the fuel electrode 3 and the electrolyte plate 1 which constitute each unit cell,
A fuel gas supply passage hole 14 and a fuel gas discharge passage hole 15 are alternately formed on the other end side of the oxygen electrode 2 so as to communicate with the fuel gas supply passage hole 28 and the fuel gas discharge passage hole 29.
A notch 16 provided in the convex portion 25 so that the fuel gas supply passage hole 26 located at one end side of the first separator 4a and the fuel gas passage 6 communicate with each other; A cutout 16 provided in the convex portion 25 so that the fuel gas discharge passage hole 29 located at the end side and the fuel gas passage 6 communicate with each other, and the fuel gas discharge passageway located at one end side of the second separator 4b. Hole 27
And the fuel gas passage 6 communicate with each other, the cutout 18 provided in the convex portion 25, the fuel gas supply passage hole 28 located on the other end side of the second separator 4b, and the fuel gas passage 6 communicate with each other. As described above, the notch 19 provided in the convex portion 25 and the external manifolds 20 and 21 for circulating the oxidizing gas through the oxidizing gas passage 5 are provided.

[Operation] When the oxidizing gas is supplied to the external manifold 20, the oxidizing gas flows through the oxidizing gas passages 5 of the first separator 4a and the second separator 4b in the same direction.

When the fuel gas is supplied to each fuel gas supply passage hole 12, the fuel gas flows through the fuel gas passage 6 of the first separator 4a in a direction intersecting with the oxidizing gas.

When the fuel gas is supplied to each fuel gas supply passage hole 14, the fuel gas is supplied to the fuel gas passage 6 of the second separator 4b with respect to the fuel gas flowing through the fuel gas passage 6 of the first separator 4a. It circulates in the opposite direction.

In this way, the fuel gas supplied from the outside of the fuel cell respectively flows in the facing direction for each adjacent single cell, so that the temperature distribution of the electrolyte plate in each single cell is flattened and The current density distribution is made uniform.

Moreover, since the oxidizing gas flows into the oxidizing gas passage 5 from the external manifold 20, it is possible to easily supply a large amount of oxidizing gas.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows in principle an example of gas flow in the fuel cell of the present invention, FIG. 2 shows the inside of one embodiment of the present invention, and FIG. 3 shows the outside of one embodiment of the present invention. It is shown.

As shown in FIG. 1, an oxygen electrode 2 is arranged on one surface of an electrolyte plate 1 and a fuel electrode 3 is arranged on the other side thereof.
The separators 4a and the second separators 4b are alternately arranged and laminated, and the oxidizing gas OG is caused to flow in the same direction in the oxidizing gas passages 5 provided on the surfaces of the first separator 4a and the second separator 4b on the oxygen electrode side. In this manner, the oxidizing gas passage 5 provided on the fuel electrode side surfaces of the first separator 4a and the second separator 4b.
The fuel gases FG-1 and FG-2 are made to flow in the fuel gas passage 6 extending in a direction substantially orthogonal to the first separator 4a and the second separator 4b so that the flow directions are opposite to each other. The oxidizing gas and the fuel gas that flow through the unit cell are in a cross flow in each stage, and the fuel gas FG-1,
The gas inlet and outlet are regulated so that only FG-2s flow in opposite directions.

In order to realize the above gas flow, the fuel cell of the present invention, as shown in FIG. 2 to FIG.
The FG-2 is made to flow by the internal manifold, and the oxidizing gas OG is made to flow by the external manifold.

4a is the first separator, 4b is the second separator,
Both separators 4a and 4b are alternately laminated between a plurality of unit cells in which the oxygen electrode 2 is arranged on one surface of the electrolyte plate 1 and the fuel electrode 3 is arranged on the other surface.

A concave fuel gas passage 6 extending from the vicinity of one end to the vicinity of the other end is formed on the fuel electrode side surfaces of both separators 4a, 4b. A concave oxidizing gas passage 5 is formed that extends in a direction substantially orthogonal to the gas passage 6.

Further, on the peripheral portions of the fuel electrode side surfaces of both separators 4a and 4b, there are convex portions that come into contact with the peripheral portions of the fuel electrode 3 forming the unit cell.
25 are formed.

26 is a fuel gas supply flow path hole (oxidation gas FG-1 supply flow path hole), 27 is a fuel gas discharge flow path hole (oxidation gas FG-2 discharge flow path hole), both flow path holes 26, 27 is each separator 4a, 4b
A plurality of protrusions 25 are alternately formed at appropriate intervals so as to be located on one end side of the.

28 is a fuel gas supply flow path hole (oxidation gas FG-2 supply flow path hole), 29 is a fuel gas discharge flow path hole (oxidation gas FG-1 discharge flow path hole), both flow path holes 28, 29 is each separator 4a, 4b
A plurality of protrusions 25 are alternately formed at appropriate intervals so as to be located on the other end side of the.

12 is a fuel gas supply flow path hole (oxidation gas FG-1 supply flow path hole), 13 is a fuel gas discharge flow path hole (oxidation gas FG-2 discharge flow path hole), both flow path holes 12, Numeral 13 is alternately bored on one end side of the fuel electrode 3, the electrolyte plate 1, and the oxygen electrode 2 constituting each unit cell so as to communicate with the fuel gas supply passage hole 26 and the fuel gas discharge passage hole 27. Has been done.

Reference numeral 14 denotes a fuel gas supply flow path hole (oxidation gas FG-2 supply flow path hole), and 15 is a fuel gas discharge flow path hole (oxidation gas FG-1 discharge flow path hole). Numeral 15 is alternately formed on the other end side of the fuel electrode 3, the electrolyte plate 1, and the oxygen electrode 2 constituting each unit cell so as to communicate with the fuel gas supply passage hole 28 and the fuel gas discharge passage hole 29. It is set up.

The notch 16 is a notch, and the notch 16 is the first separator 4a.
The convex portion 25 is provided so as to connect the fuel gas supply passage hole 26 located at one end of the fuel gas passage 6 and the fuel gas passage 6.

The notch 17 is a notch, and the notch 17 is the first separator 4a.
The convex portion 25 is provided so as to connect the fuel gas discharge passage hole 29 located on the other end side to the fuel gas passage 6.

The notch 18 is a notch, and the notch 18 is the second separator 4b.
The convex portion 25 is provided so as to connect the fuel gas discharge passage hole 27 located at one end of the fuel gas passage 6 and the fuel gas passage 6.

The notch 19 is a notch, and the notch 19 is the second separator 4b.
The convex portion 25 is provided so as to connect the fuel gas supply passage hole 28 located on the other end side to the fuel gas passage 6.

Therefore, the fuel gas FG-1 flowing to the fuel gas supply passage hole 26
Is the fuel flowing from the notch 16 through the fuel gas passage 6 from one end side to the other end side, recovered through the notch 17 to the fuel gas discharge flow passage hole 29, and flowing to the fuel gas supply flow passage hole 28. gas
The FG-2 flows from the notch 19 through the fuel gas flow path 6 from the other end side to the one end side, is recovered to the fuel gas discharge flow path hole 27 through the notch 18, and is in the fuel gas passage of the first separator 4a. A counter flow is formed in which the flow direction of the fuel gas FG-1 flowing through 6 is opposite to the flow direction of the fuel gas FG-2 flowing through the fuel gas passage 6 of the second separator 4b. On the other hand, the separator 4a,
The outer manifold 20 and the outer manifold 20 are provided so as to cover the side surfaces of the stack outside without providing any flow passage holes for the oxidizing gas in the peripheral portions of both ends of the gas passage 5 of 4b and the peripheral portion of the electrolyte plate 1 in the same direction. 21 is attached airtightly, and the oxidizing gas supplied through the oxidizing gas supply pipe 22 connected to the external manifold 20.
The OG is distributed from the inside of the external manifold 20 to each stage so as to flow in the same direction along the gas passage 5 of each separator 4a, 4b. An oxidizing gas exhaust pipe 23 is also connected to the external manifold 21, so that the oxidizing gas OG discharged to the external manifold 21 is exhausted from the exhaust pipe 23.

In addition, each fuel gas supply flow path hole 12, 26, 14, 28 for fuel gas
And the respective fuel gas discharge flow passage holes 13, 27, 15, 29 are connected to the pipes outside the fuel cell stack.

Now, the fuel gas FG-1 is supplied to the fuel gas supply passage holes 12 and 26, the fuel gas FG-2 is supplied to the fuel gas supply passage holes 14 and 28, and the oxidizing gas OG is supplied to the external manifold 20. When supplied, the fuel gas FG-1 flows through the fuel gas passage 6 of the first separator 4a from one end side toward the other end side.
In the fuel gas passage 6 of the separator 4b, the fuel gas FG-2 flows from the other end side toward the one end side, and both separators 4a, 4b
The oxidizing gas OG flows in the oxidizing gas flow paths 5 in the same direction.

That is, the fuel gas FG-1 and the oxidizing gas OG that flow through the separator 4a are in a cross flow, and the fuel gas FG-2 and the oxidizing gas OG that flow in the separator 4b are also in a cross flow, and the electrolyte plate 1 is in between. Both the flowing fuel gas FG-1 and the oxidizing gas OG, or the flowing fuel gas FG-2 and the oxidizing gas OG are in a cross flow. on the other hand,
The fuel gas FG-1 and FG-2 in each stage are in opposite flow. As a result, in the case of the cross flow type, the hot spots generated on the inlet side of the fuel gas and on the outlet side of the oxidizing gas have different positions in each stage, and the electrolyte is generated by the heat conduction action of the electrolyte plates 1. The temperature distribution of the plate 1 is flattened and the current density distribution is averaged.

There is a flow rate difference between the oxidizing gas and the fuel gas, and the oxidizing gas flow rate is usually large. In such a case, the oxidizing gas having a large flow rate is supplied to the external manifolds 20 and 21 as in the above embodiment. This is advantageous because it can be structurally easily realized.

It should be noted that the present invention is not limited to the above-described embodiment, and for example, the case where the fuel gas is allowed to flow only from one of the gas passages 6 of the separators 4a and 4b to the other is shown. The supply flow path hole and the discharge flow path hole provided on one end side of the gas path 6 of 4b communicate with each other through the gas path, and the supply flow path hole and the discharge flow path hole also provided on the other end side connect the gas path. A partition for partitioning the gas passage is provided so as to communicate with each other, and the flow direction is such that when the fuel gas supplied from one end side flows through the gas passage from one end side to the other end side, it makes a U-turn and is returned to the one end side. Of course, the flow direction of the gas flowing through the internal manifold may be other than the above, and when the flow rate difference between the gas flowing through the external manifold and the internal manifold is small, the above-mentioned embodiment may be adopted. You can reverse the above.

FIG. 4 shows an example in which a cooling device 24 of another system is installed in the stack. By adopting an external manifold, the cooling device 24 can be easily installed, which is advantageous when stack cooling is required.

[Effects of the Invention] As described above, according to the fuel cell of the present invention, the oxidizing gas is directed in the same direction in the oxidizing gas passages 5 provided on the surfaces of the first separator 4a and the second separator 4b on the oxygen electrode side. The first separator 4a and the second separator 4b are made to flow, and the fuel gas is supplied to a fuel gas passage 6 extending in a direction substantially orthogonal to the oxidizing gas passage 5 provided on the fuel electrode side surfaces of the first separator 4a and the first separator 4b. Since the flowing directions are opposite in 4a and the second separator 4b, the following excellent effects can be obtained.

(i) The hot spots appearing on the electrolyte plate of one stage are moved to different positions on the electrolyte plate of the next stage, and the temperature of the hot spots of one electrolyte plate is transmitted to another adjacent electrolyte plate. As a result, the heat conduction effect between the electrolyte plates flattens the temperature distribution of the electrolyte plates and makes the current density distribution uniform.

(ii) By the above (i), the electrolyte plate can be made uniform at the optimum temperature over its entire surface, and the composition ratio of the fuel gas and the oxidizing gas can be kept uniform, so that the entire surface of the electrolyte plate can be used with its maximum performance. A high current density can be obtained to improve the performance of the fuel cell.

(iii) Since the current density is uniform, the wear of the electrolyte plate does not locally increase, and the life of the battery can be extended.

(iv) The temperature distribution of the electrolyte plates, electrodes, and separators that make up the battery are in the direction of homogenization, and since the temperature gradient is small, thermal stress is less likely to occur, and hot spots are dispersed in the electrolyte plates, so the electrolyte It is unlikely that the plate will be damaged,
Highly stable and reliable battery performance.

(v) Since one gas is made to flow to the internal manifold and the other gas is made to flow to the external manifold, it is not necessary to provide gas passage holes in the entire peripheral portion of the electrolyte plate, and the effective area of the electrolyte plate is increased.

(vi) When the flow rate difference between the two types of gas is large, the gas with the higher flow rate can be passed through the external manifold that can flow a large flow rate structurally, and the gas with the higher flow rate can not be passed through the internal manifold. Although it is necessary to make the flow path holes large and the distribution is difficult, this can be prevented.

[Brief description of drawings]

FIG. 1 is a diagram showing in principle an example of a gas flow type in the fuel cell of the present invention, FIG. 2 is an internal schematic diagram showing an example of the fuel cell of the present invention, and FIG. 3 is a fuel cell of the present invention. FIG. 4 is a perspective view showing the outside of an example of the fuel cell of the present invention, and FIG. 5 is an explanatory view of another example of the fuel cell of the present invention. FIG. 6 is a perspective view of a cross flow type fuel cell, FIG. 7 (A) is a diagram showing the temperature distribution of the fuel cell of FIG. 6, and FIG. 7 (B) is a current density of the fuel cell of FIG. FIG. 8 is a perspective view of a conventional external manifold type fuel cell showing the distribution. 1 is an electrolyte plate, 2 is an oxygen electrode, 3 is a fuel electrode, 4a is a separator (first separator), (4b) is a separator (second separator), 5 is an oxidizing gas passage, 6 is a fuel gas passage, 1
2, 14, 26, 28 are fuel gas supply passage holes, 13, 15, 27, 29
Is a fuel gas discharge passage hole, 16, 17, 18, 19 are notches, 20, 21
Indicates an external manifold.

Claims (1)

[Claims] 1. A first separator (4a) alternately laminated between a plurality of unit cells in which an oxygen electrode (2) is arranged on one surface of an electrolyte plate (1) and a fuel electrode (3) is arranged on the other surface. And the second separator (4
b), a concave fuel gas passage (6) formed on the fuel electrode side surface of the first separator (4a) and the second separator (4b) and extending from the vicinity of one end to the vicinity of the other end, Separator (4a),
A concave oxidant gas passage (5) formed on the surface of the second separator (4b) on the oxygen electrode side and extending in a direction substantially orthogonal to the fuel gas passage (6); and a first separator (4a), A convex portion (2) formed on the peripheral portion of the fuel electrode side surface of the second separator (4b) and contacting the peripheral portion of the fuel electrode (3) constituting the unit cell.
5), each first separator (4a), second separator (4b)
Fuel gas supply passage holes (26) and fuel gas discharge passage holes (2
7), each first separator (4a), second separator (4b)
Of the fuel gas supply passage hole (28) and the fuel gas discharge passage hole (2
9), the fuel electrode (3) constituting each unit cell, the electrolyte plate (1), the oxygen electrode (2) at one end side of the fuel gas supply passage hole (26) and the fuel gas discharge passage hole (27) ), The fuel gas supply passage hole (12) and the fuel gas discharge passage hole (13) alternately formed so as to communicate with each other), the fuel electrode (3) constituting each unit cell, and the electrolyte plate.
(1), the fuel gas supply channel hole (28) at the other end of the oxygen electrode (2)
And a fuel gas supply passage hole (14) and a fuel gas discharge passage hole (15), which are alternately provided so as to communicate with the fuel gas discharge passage hole (29), and the first separator (4a). A notch (16) provided in the convex portion (25) so that the fuel gas supply flow path hole (26) located at one end side of the and the fuel gas passage (6) communicate with each other, and the first separator (4a) Of the fuel gas discharge passage hole (29) located on the other end side of the fuel gas passage (6) and the convex portion (2
Notch (17) provided in 5), fuel gas discharge passage hole (27) and fuel gas passage located at one end side of the second separator (4b)
The notch (18) provided in the convex portion (25) so as to communicate with (6),
A cutout (19) provided in the convex portion (25) so that the fuel gas supply passage hole (28) located on the other end side of the second separator (4b) and the fuel gas passage (6) communicate with each other; External manifolds (20), (2) for circulating the oxidizing gas through the oxidizing gas flow path (5)
1) A fuel cell comprising: