JPH0950817A - Fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell of which current density can be uniformalized in a reaction gas inlet side and an outlet side in an anode and a cathode. SOLUTION: A rib 3 and a gas groove 4 formed on the side (an anode side reaction part 25) of a separator sheet 2 opposed to an anode 13 are so formed as to be narrow and deep in the anode gas outlet side 25b as compared with those in the anode gas inlet side 25a. The ratio (rib ratio) of the width of the rib 3 to the total of the width of the rib 3 and the width of the gas groove 4 is set to be at least 0.4 and at most 0.7. The width of the rib 3 is set to be at least 0.2mm and at most 0.4mm.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a fuel cell,
Particularly, it relates to improvement of the separator plate.

[0002]

2. Description of the Related Art A fuel cell has an anode gas (hydrogen-rich fuel gas) and a cathode gas (oxidizer gas such as air).
Is supplied, and electricity is generated by the electrochemical reaction at that time. A laminated fuel cell that is advantageous for taking out a high voltage is configured by alternately stacking a plurality of cells in which an anode is arranged on one side of an electrolyte layer and a cathode is arranged on the other side, and a separator plate. Ribs and gas flow passages (gas grooves) are formed in the portion of the separator plate facing the anode and cathode.

Here, the separator plate is located between the cells to separate the anode gas and the cathode gas, the rib serves to collect current from the anode and the cathode, and the gas groove is formed in the anode and the cathode. It works to efficiently distribute and distribute the anode gas and the cathode gas, respectively. By the way, considering the efficiency of distribution and distribution of anode gas and cathode gas, the efficiency of current collection, etc., the ribs and gas grooves may have a square, rectangular, trapezoidal cross section, or the width of the gas grooves and the width of the ribs should be as narrow as possible. The idea was to form it.

[0004]

In such a conventional fuel cell, since the rib and the gas groove are generally formed in the same way on the gas inlet side and the gas outlet side, the gas inlet having a high gas concentration is formed. There is a problem in that the current density is high on the side of the cell and low on the gas outlet side, and the current density in the plane of the cell becomes non-uniform. This problem was remarkable on the anode side (fuel gas side).

Measures against the above problems have been considered, for example, in Japanese Patent Application No. 2-107191, gas is introduced from the gas inlet side by means such as forming the gas groove width smaller on the gas inlet side than on the gas inlet side. A fuel cell is disclosed in which the gas flow resistance is higher on the outlet side.
In this case, since a large amount of reaction gas is supplied also to the gas outlet side, the effect of making the current density uniform can be obtained.

However, when the gas groove width is formed small on the gas outlet side as described above, the supply of the reaction gas to the portion facing the gas groove of the anode or the cathode can be made uniform, but a comparison is made. Since it is considered that there is not so much effect of uniformizing the portion facing the rib where the reactive gas is hard to spread, it is not preferable for uniforming the current density in any portion of the anode and the cathode.

Therefore, in view of the above problems, the present invention provides a fuel cell in which the current density can be made uniform on the inlet side and the outlet side of the reaction gas even at the locations facing the ribs of the anode and the cathode. Is intended.

[0008]

As described above, in power generation in a fuel cell, an anode gas (fuel gas) is supplied to the cell anode and a cathode gas (oxidant gas) is supplied to the cathode, and these are subjected to an electrochemical reaction. Done by doing. Therefore, the anode gas is consumed in the anode when flowing through the anode gas groove, and the concentration of the anode gas becomes lower on the outlet side than on the anode gas inlet side. That is, the concentration of the anode gas supplied to the anode tends to be lower on the outlet side than on the anode gas inlet side, and the current density of the cell tends to be lower.

Therefore, in order to solve the above-mentioned problems, in the fuel cell according to claim 1, a cell in which an anode and a cathode are arranged in an electrolyte layer and an anode gas groove through which an anode gas flows on a surface facing the anode. In the fuel cell in which a separator plate in which ribs for collecting current from the anode are alternately formed is stacked, the rib width is smaller on the outlet side than on the anode gas inlet side.

The smaller the rib width is, the more the diffusibility of the anode gas to the anode is improved. Therefore, by making the rib width smaller on the outlet side than on the anode gas inlet side, the supply of the anode gas to the anode can be improved. . Therefore, it is possible to compensate for the decrease in the current density due to the decrease in the concentration of the anode gas and to make the current density of the cell uniform on the inlet side and the outlet side of the anode gas.

According to a second aspect of the fuel cell, the groove width of the anode gas groove is smaller on the outlet side than on the anode gas inlet side. The smaller the groove width of the anode gas groove, the more improved the current collection performance from the anode of the rib. This can further enhance the effect of making the current density of the cell uniform on the anode gas inlet side and the anode gas outlet side.

In the fuel cell according to claim 3, the anode and the cathode are rectangular, and the number of the anode gas grooves and the ribs in the separator plate is
It is characterized in that there are more outlet sides than anode gas inlet sides. Therefore, the widths of the anode gas grooves and ribs can be made smaller on the outlet side than on the anode gas inlet side while forming the plurality of anode gas grooves and ribs formed in the separator plate in parallel with each other.

The fuel cell according to claim 4 is characterized in that the anode gas groove is formed deeper on the outlet side than on the inlet side of the anode gas. Therefore, it is possible to suppress the pressure loss of the anode gas caused by forming the groove width of the anode gas groove smaller on the outlet side than on the anode gas inlet side.

In the fuel cell according to the present invention, the anode is fan-shaped, and the anode gas grooves and the ribs are formed radially corresponding to the fan-shaped anode. I am trying. Therefore, the width of the anode gas groove and the rib can be continuously reduced from the anode gas inlet side to the outlet side.

In the fuel cell according to the sixth aspect, the ratio of the rib width to the sum of the rib width and the groove width is 0.
It is characterized by being in the range of 4 or more and 0.7 or less. This ratio is in a range determined by experiments and is a preferable value for the performance of the fuel cell.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to the drawings. (Embodiment 1) FIG. 1 is a partially exploded perspective view of a fuel cell of this embodiment. The fuel cell of this example is a solid electrolyte type, and is constituted by alternately stacking a predetermined number of cells 1 and separator plates 2 and pressing the upper and lower end surfaces thereof with a pair of end plates (not shown). Here, the cell 1 and the separator plate 2
The number of stacked sheets of and is set to several tens to several hundreds depending on the required power generation voltage, the size of the device, etc., but is omitted in FIG.

In the cell 1, as shown in FIG. 1, a cathode 12 is arranged on the upper surface of the central portion of a solid electrolyte plate 11, and an anode 13 is arranged on the lower surface (in plane symmetry with the cathode 12 with the electrolyte plate 11 in between). Is configured. Openings 14, 14 for forming the anode gas discharge side internal manifold are formed at both front ends of the electrolyte plate 11, and an opening 15 for forming the cathode gas supply side internal manifold is formed in the front center part. It has been opened. On the other hand, an opening (not shown) for forming an anode gas supply side internal manifold is formed in the rear center of the electrolyte plate 11.

The separator plate 2 is made of nickel chromium alloy (Inconel) and has a predetermined size (for example, 150 mm).
× 150 mm × 4 mm). 2 is a plan view of the lower surface side of the separator plate 2 in FIG. Hereinafter, description will be made with reference to FIG. On both upper and lower surfaces of the separator plate 2, the portions facing the cathode 12 and the anode 13 when laminated (hereinafter referred to as the cathode side reaction section 24 and the anode side reaction section 25, respectively) are parallel to the gas flow direction. Then, a plurality of ribs 5, 3 and gas grooves 6, 4 are formed. In FIG. 1, the cathode side reaction section 24 is not shown because it is located on the back side of the anode side reaction section 25.

Openings 2 for forming internal manifolds on the anode gas discharge side are formed at both front ends of the separator plate 2.
1, 21 are opened, and an opening 22 for forming the cathode gas supply side internal manifold is formed in the front center part. On the other hand, an opening 23 for forming an anode gas supply side internal manifold is formed in the rear center of the separator plate 2. Here, the openings 21, 22, and 23 of the separator 2 are adapted to overlap the openings 14 and 15 and the like of the cell 1 when laminated.

The openings 22 and 23 are formed in the partition wall 2.
It is divided into a plurality of openings 22a and 23a by a and 2b. As a result, the mechanical strength of the front and rear ends of the separator plate 2 is maintained, and the cathode gas and the anode gas are supplied to the plurality of gas grooves 6, 6 ...
Can be evenly distributed over. On the other hand, recesses 26, 26 (not shown in FIG. 1) are formed at both rear ends of the lower surface of the separator plate 2, and the recesses 26, 26 are formed.
The cathode gas is discharged to the outside of the fuel cell through the.

Then, the ribs 5 and 3 and the gas grooves 6 and 4 are formed.
The configuration of will be described. FIG. 3A shows X in FIG.
It is a partially enlarged view of the 1-X1 line cross section, (b) is X2-X.
It is a partially expanded view of a two-line cross section. First, the rib 5 and the cathode gas groove 6 formed in the cathode side reaction portion 24 are
As shown in FIGS. 2 and 3, the width is 1.8 mm and the height (depth) is 1 mm.

On the other hand, as shown in FIG. 1, the anode side reaction section 25 is substantially divided into two regions, an anode gas inlet side 25a and an anode gas outlet side 25b. The rib 3a and the anode gas groove 4a formed on the anode gas inlet side 25a have a width of 1.8 mm and a height (depth) of 1 mm, as shown in FIGS. The rib 3b and the anode gas groove 4b formed on 25b have a width of 1 mm and a height (depth) of 2 mm.

That is, compared with the shapes of the ribs 3a and the gas grooves 4a on the anode gas inlet side 25a, the widths of the ribs 3b and the anode gas grooves 3b are narrower on the anode gas outlet side 25b, and the number of each rib is increased. , The anode gas outlet side 25 compared to the anode gas inlet side 25a
At b, the depth of the anode gas groove 4b is set deep. Here, the ribs 3 and 5 and the gas grooves 4 and 6 are formed by electric discharge machining.

The opening 23 and the anode gas inlet side 2
5a, and the anode gas outlet side 25b and the opening 2
The anode gas passage between the first and second ribs 1 and 1 has a depth of 1 mm from the upper surface of the rib 3. The depth between the downstream end portion 41 of the anode gas groove 4a and the upstream end portion 42 of the anode gas groove 4b continuously increases from 1 mm to 2 mm, and the depth increases again from the downstream end portion 43 of the anode gas groove 4b. 2 mm
To 1 mm continuously shallow.

In the fuel cell having the above structure, the anode gas flows through the anode gas supply manifold from the upper side to the lower side as shown in FIG.
To the anode side reaction part 25 (white arrow P
1). Then, the distributed anode gas flows through the respective anode gas grooves 4, 4 ... (White arrow P2), and after being subjected to an electrochemical reaction at the anode 13, the unreacted anode gas is converted into an anode gas exhaust manifold. Flow from above to below (white arrow P3).

On the other hand, as shown in FIGS. 1 and 2, the cathode gas flows through the cathode gas supply manifold consisting of the openings 22 and 15 from the upper side to the lower side (from the back side to the front side in FIG. 2). It is distributed to the cathode gas reaction part 24 of the separator plate 2 (white arrow P4). Then, the distributed cathode gas flows through the respective cathode gas grooves 6, 6 ... (White arrow P5), is subjected to an electrochemical reaction at the cathode 12, and then passes through the recesses 26, 26 to the outside of the fuel cell. It is discharged (white arrow P6).

By the way, as shown in FIGS. 3 (a) and 3 (b), the width of the rib 3 and the width of the anode gas groove 4 are larger than those of the anode gas inlet side 24a.
It is set to be narrow. Therefore, the longest diffusion paths J1 and J2 of the anode gas to the anode 13 are provided between the anode gas inlet side 25a and the anode gas outlet side 25b.
And the longest current path J3 and J to the rib 3 which becomes the current collector
When compared with 4 respectively, both are shorter on the anode gas outlet side 25b than on the anode gas inlet side 25a.

Here, the longest diffusion path is indicated by the arrow J in FIG.
1, J2, it means the longest path from the anode gas grooves 4a, 4b to the boundary between the anode 13 and the electrolyte plate 11. That is, the anode gas grooves 4a, 4
The path from the end of b to the position facing the center of the ribs 3a and 3b at the boundary between the anode 13 and the electrolyte plate 11.
Further, the longest current path refers to the longest path among the paths from the boundary between the anode 13 and the electrolyte plate 11 to the ribs 3a and 3b, as shown by arrows J3 and J4 in FIG. That is,
Ribs 3a, 3b from the position facing the center of the anode gas grooves 4a, 4b at the boundary between the anode 13 and the electrolyte plate 11.
Refers to the route to.

As a result, even when the concentration of the anode gas decreases as the electrochemical reaction progresses, the longest diffusion path J2 on the anode gas outlet side 25b is made smaller than that on the anode gas inlet side 25a, whereby the anode 13 The internal resistance of the fuel cell can be reduced by improving the supply of the anode gas to the anode and reducing the longest current path J4. Therefore, the current density distribution can be made uniform on the anode gas inlet side 25a and the anode gas outlet side 25b of the fuel cell.

On the anode gas outlet side 25b, the width of the anode gas groove 4 is narrowed from 1.8 mm to 1 mm, but the depth is as deep as 2 mm.
Increased pressure loss is prevented. The effect of this example is also shown by the following Experiment 1. FIG. 6 is a diagram showing a difference in power generation life characteristics between the fuel cell according to the present embodiment and the fuel cell according to the conventional example. The fuel cell of the conventional example has the same overall structure as that of the fuel cell of the present embodiment, but the shapes of the ribs 3 and the gas grooves 4 formed in the anode side reaction portion 25 of the separator plate 2 are the same. Are different. That is, the rib and the gas groove are continuously formed from the upstream side to the downstream side with a constant width of 1.8 mm and a height (depth) of 1 mm.

In Experiment 1, the fuel cells of this example and the conventional example were used to examine the temporal change in cell voltage. The electrode area of each fuel cell was 130 cm ² , and the current density was 0.5 A / c.
m ² and the anode gas utilization rate were 75%. As can be seen from FIG. 6, in the fuel cell of the conventional example, the cell voltage at the start of measurement was 0.4 V, but the cell voltage began to drop after about 150 hours had passed and reached 0.33 V after 200 hours had passed. . On the other hand, in the fuel cell of this example, the cell voltage at the start of measurement was 0.44 V, which was higher than that of the conventional example, and was 200
The cell voltage does not decrease even after the elapse of time. Therefore, it is understood that the present invention can increase the power generation voltage of the fuel cell and extend the power generation life.

In Experiment 2, by changing the width of the gas groove while keeping the width of the rib on the anode side constant, the ratio of the "anode contact area of the rib" to the "anode area" (that is, the sum of the rib width and the anode groove). The sum of the rib widths with respect to the sum of the widths) was changed and the change in cell voltage at that time was examined. In addition, the electrode area of the fuel cell was 10 cm ^2, and the rib was 1 mm in width and was provided in the anode gas flow direction in a constant manner.
The current density was 0.3 A / cm ² .

As can be seen from FIG. 7, the cell voltage has a maximum value of 0.78 V when the rib ratio is 0.55. When the rib ratio became smaller than 0.55, the cell voltage decreased. At that time, the rib ratio is 0.
4 (at this time, the cell voltage is 0.7V) is gentle, but when it becomes smaller than that, the cell voltage drastically decreases, and the rib ratio was 0.3 and the cell voltage was 0.55V. It is considered that this is because if the rib ratio becomes too small, the current collection efficiency decreases. On the other hand, the cell voltage also decreased when the rib ratio became larger than 0.55. The decreasing tendency of the cell voltage at that time is gentle until the rib ratio is 0.7 (the cell voltage is 0.75 V at this time), but when it is higher than that, the cell voltage is rapidly decreased and the rib ratio is 0.75. Then, the cell voltage became 0.45V. It is considered that this is because if the rib ratio becomes too large, the diffusibility of the anode gas with respect to the anode 13 decreases.

From the above, it is understood that the rib ratio should be set to 0.4 or more and 0.7 or less on both the anode gas inlet side 25a and the anode gas outlet side 25b in consideration of practical allowance. In Experiment 3, the rib width was changed while keeping the rib ratio constant, and the change in cell voltage at that time was examined. The electrode area of the fuel cell was 10 cm ² , the rib ratio was 0.5, and the anode gas utilization rate was 5% or less.

As can be seen from FIG. 8, the rib width is 0.4 m.
In the case of m, the cell voltage was 0.78V, but the cell voltage gradually decreased as the rib width increased, and when the rib width was 4.4 mm, the cell voltage became 0.7V.
When the rib width becomes larger, the cell voltage drops sharply.
When the rib width was 7.3 mm, the cell voltage was 0.2V.

As described above, when the rib width and the gas groove width increase, the cell voltage decreases because the anode gas diffusion path to the electrode portion increases and the diffusion of the anode gas is alienated, and the internal resistance increases. It is thought to be because. From this experimental result, it is understood that it is preferable to design the rib width to be 4 mm or less, but even if the electric discharge machining is used, at least 0.2 mm is necessary in terms of the accuracy of the design machining, so the rib width is 0.2
It is preferable to set it to be not less than mm and not more than 4 mm.

In this embodiment, the anode side reaction section 2
5 for the anode gas inlet side 25a and the anode gas outlet side 2
Although it is bisected into 5b, it is not always required to be equally divided, and it is also possible to divide into 3 or more in the anode gas flow direction. Further, although the effect is somewhat lowered, the anode gas inlet side 25a and the anode gas outlet side 2a
5b, only the width of the rib 3 or only the width of the gas groove 4 may be changed.

The shapes of the ribs 5 and the gas grooves 6 of the cathode side reaction section 24 are not limited to the above, and the ribs 3 and the anode gas grooves 4 of the anode side reaction section 25 may be of a similar shape. It is possible. (Embodiment 2) Next, a fuel cell according to Embodiment 2 will be described. Here, in this embodiment, only the configurations of the cell 1 and the separator plate 2 are different from those of the first embodiment. Therefore, regarding the basic configuration of the fuel cell,
Detailed description is omitted. FIG. 4 is a partially exploded perspective view of the fuel cell.

The cell 101 comprises a cathode 116 and an anode 117 which are fan-shaped on the upper and lower surfaces of an electrolyte plate 115.
Is formed by arranging four unit cells 101a in which the arcs of the fan-shaped cathode 116 and the anode 117 are opposed to each other. In addition, in FIG. 4, since the anode 117 is located on the back side of the cathode 116,
Not shown.

The separator plate 102 is the unit cell 10
It is configured by combining so as to correspond to the four 1a. A plurality of separator plates 102 are provided on the upper and lower surfaces of the separator plate 102 so as to cover regions facing the cathode 116 and the anode 117 of the unit cell 101a (hereinafter referred to as the cathode side reaction part 126 and the anode side reaction part 127, respectively). Rib 131 (133) and gas groove 132 (13)
4) is formed. In FIG. 4, the cathode side reaction section 126 is not shown because it is located on the back side of the anode side reaction section 127.

In the central area of the cell 101 where the cathode 116 and the anode 117 are not arranged and in the central portion of the separator plate 102, an opening for forming an internal manifold is formed. That is, the cell 101
Also, openings 118 and 121 are formed in the center of the separator plate 102 to form the circulation holes of the cathode gas. In addition, four openings 118a and 121a for forming cathode gas supply side internal manifolds are provided around the openings 118 and 121, and opening 118 for forming anode gas supply side internal manifolds are formed.
Four b and 121b are opened.

Further, the cell 101 and the separator plate 102
Corners of the fan, that is, fan-shaped cathode 116 and anode 11
Openings 119 and 122 for forming the anode gas discharge side internal manifold are formed at the respective central positions of 7. Further, a cathode gas discharge port 123 is opened on the outer peripheral wall of the side surface of the separator plate 102. With such a structure of the fuel cell, the cathode gas supplied from the outside is heated while rising in the flow passage formed by the openings 118 and 121, and then heated by the openings 118a and 121.
While being descended from the four internal manifolds consisting of a, they are distributed to the cathode gas grooves 134, 134 ... Of each separator plate 102 and used for power generation at the cathode 116. Then, the unreacted cathode gas is discharged from the cathode gas outlet 12
3 is discharged to the outside.

On the other hand, the anode gas supplied to the fuel cell from the outside descends through the four internal manifolds having the openings 119 and 122, and each separator plate 102.
Of the anode gas grooves 132, 132, ... After that, the unreacted anode gas descends through the internal manifold including the openings 119 and 122 and is discharged to the outside.

Next, details of the ribs 131 and 133 and the gas grooves 132 and 134 formed on the separator plate 102 will be described. FIG. 5 is a partially enlarged view of the lower surface side (cathode side) of the separator plate 102 (a), (b).
The partially expanded view of the upper surface side (anode side) plane is shown.
As shown in FIG. 5A, the ribs 133 and the cathode gas grooves 134 are radially formed from the center 126a near the opening 121 and cover the entire surface of the cathode side reaction section 126. The arc-shaped dotted line 116a indicates the cathode 1
The outer peripheral edge of 16 is shown. And all the ribs 133
The cathode gas grooves 134 are carved at equal intervals with respect to the center 126a so as to have a predetermined rib ratio and height (depth).

Here, the cathode gas is the opening 12
1b, flows through the cathode gas grooves 134, 134, ... And is discharged from the cathode gas discharge port 123 (white arrow P108). Therefore, the widths of the rib 133 and the cathode gas groove 134 are different from each other in the cathode gas flowing direction. Although it is configured to gradually widen from the upstream side to the downstream side, since the excess amount of air is used as the cathode gas, the difference in concentration of the cathode gas between the upstream side and the downstream side in the cathode gas flow direction is It doesn't matter.

On the other hand, as shown in FIG.
1 and the anode gas groove 132 are radially formed from the center 127a near the opening 122 and cover the entire surface of the anode side reaction section 127. And all the ribs 1
31 and the anode gas groove 132 are carved at equal intervals with respect to the center 127a so as to have a predetermined rib ratio and height (depth).

Here, the anode gas is the opening 12
1a, flows through the anode gas grooves 132, 132, ... And is discharged from the opening 122 (white arrow P1).
09), the widths of the rib 131 and the anode gas groove 132 are configured to be gradually narrowed from the upstream side to the downstream side in the anode gas flow direction. Therefore, as in Example 1, it is possible to make the current density uniform on the inlet side and the outlet side of the anode gas. Further, in this embodiment, the rib 131 and the anode gas groove 13 are provided.
Each width of 2 can be continuously changed in response to a continuous decrease in the concentration of the anode gas from the inlet side to the outlet side of the anode gas, not in a stepwise manner, so that the current density Homogenization can be performed.

In this embodiment, the widths of both the rib 131 and the anode gas groove 132 are continuously narrowed from the anode gas inlet side to the anode gas side. However, the width is not limited to this, and for example, the rib 131 may be formed. It is also possible to reduce only the width continuously. Further, although the solid oxide fuel cell is used in the above embodiment, it is of course possible to use a solid polymer membrane fuel cell, a phosphoric acid fuel cell, a molten carbonate fuel cell, or the like.

[0049]

As described above, the anode gas is subjected to the electrochemical reaction at the anode when flowing through the anode gas groove, and the concentration of the anode gas becomes lower on the outlet side than on the anode gas inlet side. As a result, the supply of the anode gas to the anode tends to be lower on the outlet side than on the anode gas inlet side, and the power generation voltage of the cell tends to lower.

Here, in the fuel cell according to the first aspect, the rib width is formed narrower on the outlet side than on the anode gas inlet side. The current density of the cell can be made uniform on the anode gas inlet side and the outlet side.
Therefore, the problem that the high current density portion of the cell is selectively deteriorated is solved, and the power generation life of the cell can be extended.

In the fuel cell according to the second aspect, the groove width of the anode gas groove is smaller on the outlet side than on the anode gas inlet side. As the groove width of the anode gas groove is smaller, the longest current path to the rib that is the current collecting portion is smaller, and the current collecting performance from the anode of the rib is improved. Therefore, the decrease in the generated voltage due to the decrease in the concentration of the anode gas is more efficiently compensated for, and the magnitude of the current density of the cell is
It is possible to make the anode gas inlet side and outlet side uniform.

In the fuel cell according to the present invention, the anode and the cathode are rectangular, and the separator plate has more anode gas grooves and ribs on the outlet side than on the inlet side of the anode gas. Therefore, the widths of the anode gas grooves and the ribs can be made smaller on the outlet side than on the anode gas inlet side while the plurality of anode gas grooves and ribs formed on the separator plate are formed parallel to each other. Therefore, the effect of shortening the width of the anode gas groove and the rib width can be shortened by simply changing the design of the ribs and gas grooves of the separator plate without significantly changing the overall configuration of the fuel cell from the conventional example. Both of these effects can be obtained, and there is no difficulty in designing the device, which is economical.

In the invention of claim 4, the anode gas groove is formed deeper on the outlet side than on the inlet side of the anode gas. When the groove width is narrowed while keeping the depth of the anode gas groove constant, the pressure loss of the anode gas flowing through the anode gas groove becomes a problem.
Since the depth of the anode gas groove is deeper on the outlet side than on the anode gas inlet side, the pressure loss of the anode gas can be suppressed. Therefore, the anode gas is efficiently supplied to the anode, and the current density in the entire cell can be made uniform.

According to the fifth aspect of the invention, since the anode is fan-shaped, the rib width and the anode gas groove width can be continuously narrowed from the upstream side to the downstream side of the anode gas. Therefore, it is possible to more smoothly make the current density uniform corresponding to the decrease in the concentration of the anode gas accompanying the progress of the electrochemical reaction. Claim 6
In the fuel cell described above, the ratio of the rib width to the sum of the rib width and the groove width is set within a range of 0.4 or more and 0.7 or less over the entire area from the anode gas inlet side to the outlet side. Has been done.

If the rib ratio is too small, the current path in the flow path portion increases and the current collection efficiency decreases, so the cell voltage decreases. On the other hand, if the rib ratio is too large, the diffusion path of the anode gas to the electrode portion increases and the diffusibility of the anode gas to the anode decreases, so that the cell voltage decreases. Therefore,
There is an optimum value for the ratio of the rib width to the sum of the rib width and the anode gas groove width. Considering the practically allowable range, it is preferable to set the rib ratio to 0.4 or more and 0.7 or less. Within this range, the current density in the entire cell can be effectively equalized, and It is possible to prolong the life of power generation by preventing partial deterioration of the.

[Brief description of drawings]

FIG. 1 is a partially exploded perspective view of a fuel cell according to a first embodiment.

2 is a plan view of the lower surface side (cathode side) of the separator plate in FIG. 1. FIG.

3A is a partially enlarged view of a cross section taken along line X1-X1 in FIG. 1, and FIG. 3B is a partially enlarged view of a cross section taken along line X2-X2.

FIG. 4 is a partially exploded perspective view of a fuel cell according to a second embodiment.

FIG. 5 is a partially enlarged view of the (a) lower surface side (cathode side) plane of the separator plate of the fuel cell according to Example 2;
(B) It is a partially enlarged view of an upper surface side (anode side) plane.

FIG. 6 is a diagram showing a difference in power generation life characteristics between the fuel cell according to the first embodiment and the fuel cell according to the conventional example.

7 is a diagram showing a relationship between a cell ratio and a rib ratio (that is, a sum of rib widths with respect to a sum of rib widths and a sum of anode groove widths) of the fuel cell according to Example 1. FIG.

FIG. 8 is a diagram showing the relationship between the cell width and the rib width (constant rib ratio) of the fuel cell according to the first embodiment.

[Explanation of symbols]

 1, 101 cell 2, 102 separator plate 3 (3a, 3b), 131 rib 4 (4a, 4b), 132 anode gas groove 12, 116 cathode 13, 117 anode 25a anode gas inlet side 25b anode gas outlet side

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Yukinori Akiyama 2-5-5 Keihan Hondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd. (72) Inventor Yasuhiko Ito, 2-5 Keihan Hondori, Moriguchi City No. 5 Sanyo Electric Co., Ltd. (72) Inventor Yasuo Miyake 2-5-5 Keihan Hondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd.

Claims (6)

[Claims] 1. A separator plate in which a cell in which an anode and a cathode are arranged in an electrolyte layer, an anode gas groove through which an anode gas flows and a rib which collects current from the anode are alternately formed on a surface facing the anode. In the fuel cell, the rib width is smaller on the outlet side than on the inlet side of the anode gas. 2. The fuel cell according to claim 1, wherein the width of the anode gas groove is smaller on the outlet side than on the anode gas inlet side. 3. The anode and the cathode have a rectangular shape, and in the separator plate, the number of the anode gas grooves and the ribs is larger on the outlet side than on the anode gas inlet side. And the fuel cell described in 2. 4. The fuel cell according to claim 1, wherein the anode gas groove is formed deeper on the outlet side than on the anode gas inlet side. 5. The anode is fan-shaped, and the anode gas groove and the rib are formed radially corresponding to the fan-shaped of the anode. Fuel cell. 6. The ratio of the rib width to the sum of the rib width and the groove width is in the range of 0.4 or more and 0.7 or less over the entire area from the inlet side to the outlet side of the anode gas. The fuel cell according to claim 1, wherein the fuel cell is a fuel cell.