JP6679443B2 - Fuel cell - Google Patents

Description

  The present invention relates to a fuel cell including a separator facing an electrolyte membrane / electrode structure.

  A unit cell of a polymer electrolyte fuel cell is configured by sandwiching an electrolyte membrane / electrode structure (MEA) between a pair of separators (for example, Patent Document 1). The electrolyte membrane / electrode structure has an electrode catalyst layer provided with a catalyst and a gas diffusion layer for supplying a fuel gas and an oxidant gas to the electrode catalyst layer, which are laminated on both sides of an electrolyte membrane made of an electrolyte polymer. Composed.

  A gas passage is provided in the separator. The gas flow path extends along the gas diffusion layer, and the gas flowing through the gas flow path diffuses into the gas diffusion layer and further reaches the electrode catalyst layer. Electrochemical reaction occurs in the electrode catalyst layer to generate power.

  However, in the gas flow path extending along the gas diffusion layer as described above, for example, when generated water or the like accompanying the electrochemical reaction stays in the gas diffusion layer, diffusion of gas from the gas flow path is hindered. There is a risk that they will be caught. In this case, the gas passes through the gas flow path without being supplied to the gas diffusion layer and is discharged from the unit cell, and as a result, the power generation efficiency of the fuel cell may decrease.

  Therefore, for example, in Patent Document 2, a separator capable of supplying gas along the stacking direction of the electrolyte membrane / electrode structure regardless of whether the generated water or the like is retained in the gas diffusion layer. Has been proposed. Specifically, this separator is provided with a plurality of rectangular tube-shaped gas supply passages and gas discharge passages arranged side by side with one end in the extending direction closed and the other end open. Rectangular supply holes and discharge holes are provided on the side walls of the gas supply passage and the gas discharge passage that face the gas diffusion layer.

  As described above, by supplying gas from the opening at the other end to the gas supply channel whose one end is closed to increase the internal pressure, almost all of the gas supplied to the gas supply channel is passed through the supply hole. Can be supplied along the stacking direction of the electrolyte membrane / electrode structure. Of the gas thus supplied to the electrolyte membrane / electrode structure from the supply holes, the residual gas that has not been consumed by the electrochemical reaction in the electrode catalyst layer flows to the gas discharge flow path through the discharge holes. It flows in and is discharged from the opening of the discharge flow path.

Japanese Patent No. 5042618 JP, 2006-114414, A

  As described above, when the gas is supplied along the stacking direction of the electrolyte membrane / electrode structure, the gas concentration in the vicinity of the discharge hole may be higher than that in the vicinity of the supply hole of the electrode catalyst layer depending on the arrangement of the supply hole and the discharge hole. Since it becomes low, it becomes difficult to sufficiently cause an electrochemical reaction in the vicinity of the discharge hole. That is, there is a concern that the power generation efficiency of the fuel cell may decrease due to the variation in the gas concentration that occurs in the in-plane direction of the electrode catalyst layer.

  The present invention solves this kind of problem, and can supply gas to the electrolyte membrane / electrode structure satisfactorily, and further, it is possible to suppress the occurrence of variations in gas concentration in the in-plane direction of the electrode catalyst layer. An object of the present invention is to provide a fuel cell exhibiting excellent power generation efficiency.

  In order to achieve the above-mentioned object, the present invention is a fuel cell including a separator facing an electrolyte membrane / electrode structure, wherein the separator has a supply opening for closing gas at one end and supplying gas at the other end. A gas supply channel having a plurality of supply holes for discharging the gas supplied from the supply opening at a predetermined interval on a side wall facing the electrolyte membrane / electrode structure; A gas discharge having a discharge opening for discharging the gas at an end, and a plurality of discharge holes into which the gas discharged from the supply hole flows are provided at predetermined intervals on a side wall facing the electrolyte membrane / electrode structure. And a plurality of the gas supply passages and the gas discharge passages are alternately arranged in parallel, and in the rectangular shape of the four discharge holes adjacent to the one supply hole, the long side of the short side The ratio of length Characterized in that it is a .00～1.33.

  In the fuel cell according to the present invention, the gas supplied from the supply opening at the other end is supplied to the gas supply passage whose one end is closed, thereby increasing the internal pressure of the gas supply passage and discharging the gas from the supply hole. The pressure can be increased. As a result, for example, almost all of the gas supplied to the gas supply passage is irrespective of whether or not the water produced by the electrochemical reaction in the electrode catalyst layer remains in the gas diffusion layer. It can be satisfactorily supplied along the stacking direction of the structure.

  At this time, the arrangement of the supply holes is adjusted so that the ratio of the length of the long side to the length of the short side is 1.00 to 1.33 in the rectangular shape of the four supply holes adjacent to one discharge hole. ing. Here, even when the length ratio is 1.00 and the square is a square, one side of the rectangle is called a short side and the other side is called a long side for convenience of explanation. That is, the short side and the long side may have the same length. The gas discharged from the supply hole diffuses as a spherical wave in the electrolyte membrane / electrode structure.Therefore, by arranging the supply hole under the above conditions, the gas generated in the in-plane direction of the electrode catalyst layer. It is possible to sufficiently reduce variations in density. That is, it becomes possible to effectively cause an electrochemical reaction in the electrode catalyst layer.

  From the above, according to the fuel cell of the present invention, it is possible to satisfactorily supply the gas to the electrode catalyst layer while suppressing the variation of the gas concentration in the in-plane direction to promote the electrochemical reaction. Therefore, the power generation efficiency can be improved.

  In the above fuel cell, it is preferable that the supply holes are arranged at positions of intersections of diagonal lines of the rectangle. In this case, the variation in gas concentration between the vicinity of the supply hole and the vicinity of the discharge hole of the electrode catalyst layer can be further reduced, so that the electrochemical reaction in the entire electrode catalyst layer is promoted and the power generation efficiency of the fuel cell is improved. It is possible to further improve.

  In the above fuel cell, it is preferable that at least one of the supply hole and the discharge hole has a circular shape in a plan view. In this case, as described above, the gas diffusing as a spherical wave can be more smoothly circulated through the supply hole or the discharge hole, and the electrochemical reaction in the electrode catalyst layer can be promoted. It is possible to further improve the power generation efficiency of the fuel cell.

In the above fuel cell, the separator includes a plate member integrally forming the side wall facing the electrolyte membrane / electrode structure of each of the gas supply flow path and the gas discharge flow path, and the plate member. by superposed, that having a, a Mizoban member having a plurality juxtaposed plurality of gas supply passage groove and the gas discharge flow passage are alternately constituting the gas supply passage and the gas discharge channel . In this case, a separator having a plurality of gas supply passages and gas discharge passages can be easily obtained with a simple configuration, and in turn, the manufacturing cost of the fuel cell can be reduced.

  In the fuel cell according to the present invention, one end is closed, the other end is provided with a supply opening, and a plurality of supply holes are provided in a side wall facing the electrolyte membrane / electrode structure. Gas is supplied through the opening. As a result, the internal pressure of the gas supply channel can be increased and the pressure of the gas discharged from the supply hole can be increased. Therefore, almost all of the gas supplied to the gas supply channel can be applied to the electrolyte membrane / electrode structure. , Can be satisfactorily supplied along the stacking direction.

  In addition, in a rectangle formed by the four discharge holes adjacent to one supply hole, the ratio of the length of the long side to the length of the short side is 1.00 to 1.33. Therefore, as described above, even if the gas is supplied from the supply hole along the stacking direction of the electrolyte membrane / electrode structure, it is possible to suppress the variation in the gas concentration in the in-plane direction of the electrode catalyst layer, The electrochemical reaction can be effectively caused. As a result, the power generation efficiency of the fuel cell can be improved.

It is a principal part exploded perspective view of the fuel cell which concerns on embodiment of this invention. It is a front view of the plate member side of the separator of FIG. 6 is a graph showing the relationship between the ratio (long side / short side) of the second line segment L2 (long side) to the first line segment L1 (short side) and the cell voltage of the fuel cell.

  Hereinafter, preferred embodiments of a fuel cell according to the present invention will be described in detail with reference to the accompanying drawings.

  As shown in FIG. 1, the unit cell of the fuel cell 10 according to this embodiment includes an electrolyte membrane / electrode structure 12, a separator 14 facing one surface of the electrolyte membrane / electrode structure 12, and an electrolyte membrane / electrode. And a separator (not shown) facing the other surface of the structure 12. Since the separator (not shown) is configured almost the same as the separator 14, the description of the separator 14 will be omitted below.

  The electrolyte membrane / electrode structure 12 includes an electrolyte membrane made of an electrolyte polymer, electrode catalyst layers serving as reaction sites for electrode reactions on both sides of the electrolyte membrane, and a fuel gas or an oxidant gas in each of the electrode catalyst layers. And a gas diffusion layer for diffusing and supplying a gas such as the above. That is, the electrode catalyst layers are arranged on both sides of the electrolyte membrane, and the gas diffusion layers are further arranged on both sides of the electrode catalyst layer. It should be noted that illustration of each component of the electrolyte membrane / electrode structure 12 is omitted.

  The separator 14 is, for example, a rectangular shape made of steel, stainless steel, titanium, aluminum, plated steel, or a metal whose surface has been subjected to surface treatment for corrosion prevention, carbon, or the like, and the plate member 20 and the groove plate. It has a member 22. The plate member 20 faces the gas diffusion layer of the electrolyte membrane / electrode structure 12, and is formed with a plurality of supply holes 24 and discharge holes 26 as will be described later.

  The groove plate member 22 has a plurality of gas supply flow channel grooves 32 and gas discharge flow channel grooves 34 extending along the short side direction of the groove plate member 22 in a predetermined direction in the long side direction of the groove plate member 22. A plurality of them are alternately arranged side by side at intervals. A gas supply port 40 is provided on one end side of the groove plate member 22 in the short side direction, and the gas supply port 40 extends along the long side direction of the groove plate member 22. To communicate with each of the plurality of gas supply flow channel grooves 32. On the other hand, a gas discharge port 44 is provided on the other end side of the groove plate member 22 in the short side direction, and the gas discharge port 44 extends along the long side direction of the groove plate member 22. It communicates with each of the plurality of gas discharge channel grooves 34 via 46.

  As shown in FIG. 2, the plate member 20 and the groove plate member 22 are overlapped so that the supply hole 24 faces the gas supply flow channel groove 32 and the discharge hole 26 faces the gas discharge flow channel groove 34. Positioned and fixed with. As a result, the gas supply passage 50 is formed between the gas supply passage groove 32 and the plate member 20, and the gas discharge passage 52 is formed between the gas discharge passage groove 34 and the plate member 20.

  That is, the side walls of the gas supply flow path 50 and the gas discharge flow path 52 facing the electrolyte membrane / electrode structure 12 are integrally formed by the plate member 20. Further, the gas supply passages 50 and the gas discharge passages 52 extend along the short side direction of the separator 14 and are alternately arranged at predetermined intervals in the long side direction of the separator 14.

  The gas supply flow path 50 is provided with a supply opening 54 that is closed at one end and that is connected to the gas supply port 40 through the gas supply communication passage 42 at the other end. Therefore, the gas (hereinafter, also simply referred to as gas) such as the fuel gas and the oxidant gas supplied from the gas supply port 40 to the gas supply communication passage 42 flows into the gas supply passage 50 through the supply opening 54. To do. The gas discharge flow path 52 is provided with a discharge opening 56 which is closed at one end and communicates with the gas discharge port 44 through the gas discharge communication passage 46 at the other end. The gas in the gas discharge passage 52 flows into the gas discharge communication passage 46 through the discharge opening 56 and is discharged from the gas discharge port 44 to the outside of the separator 14.

  The supply hole 24 has, for example, a circular shape with a diameter of approximately 0.1 to 3.0 mm in plan view, and has a predetermined interval (to 20 mm) in the extending direction of each of the plurality of gas supply flow paths 50. Plural are arranged. As a result, the gas in the gas supply channel 50 can be discharged through the supply holes 24 along the stacking direction of the electrolyte membrane / electrode structure 12.

  The discharge hole 26 has, for example, a circular shape with a diameter of approximately 0.1 to 3.0 mm in plan view, and has a predetermined interval (up to 20 mm) in each extending direction of the plurality of gas discharge flow paths 52. Plural are arranged. As a result, of the gas supplied to the electrolyte membrane / electrode structure 12, the residual gas that has not been consumed by the electrochemical reaction in the electrode catalyst layer flows into the gas discharge passage 52 through the discharge hole 26. Is possible.

  That is, the supply holes 24 and the discharge holes 26 are arranged in the plate member 20 in a lattice point shape. Specifically, the long side (the first line segment L1 in FIG. 2) of the short side (first line segment L1 in FIG. 2) of the rectangle S having the four adjacent discharge holes 26, 26, 26, 26 surrounding the one supply hole 24 as the vertices. The length ratio of the second line segment L2) in FIG. 2 is set to be 1.00 to 1.33. Further, a supply hole 24 is provided at a position which is an intersection of the diagonal lines of the rectangle S. Here, even when the length ratio is 1.00 and the square S is a square, one side (first line segment L1) of the square S is called a short side and the other side (for convenience of description). The second line segment L2) is called the long side. That is, the short side and the long side may have the same length.

  Basically, the operation and effect of the fuel cell 10 configured as described above will be described in relation to its operation.

  First, gas is supplied from the gas supply port 40 to the gas supply communication passage 42. This gas is introduced into the gas supply flow path 50 through the supply opening 54, respectively. Since one end of the gas supply channel 50 is closed, only the supply hole 24 having a smaller diameter than the supply opening 54 serves as a gas outlet. Therefore, the gas whose pressure is increased in the gas supply passage 50 is discharged from the supply hole 24. As a result, for example, almost all of the gas supplied to the gas supply channel 50 is supplied from the supply hole 24 to the electrolyte membrane regardless of whether or not the water produced by the electrochemical reaction is retained in the gas diffusion layer. It can be satisfactorily supplied along the stacking direction of the electrode structure 12.

  The gas thus supplied from the supply hole 24 reaches the electrode catalyst layer while being further diffused in the gas diffusion layer, and is consumed by the electrochemical reaction in the electrode catalyst layer. At this time, the arrangement of the discharge holes 26 is set so that the ratio of the second line segment L2 to the first line segment L1 is within the above range, and the discharge holes 26, 26, 26, 26 are supplied as described above. A hole 24 is provided. Further, the supply hole 24 and the discharge hole 26 are circular in plan view. As a result, the spherical wave gas can be smoothly circulated in the electrolyte membrane / electrode structure 12 and effectively diffused, so that the gas between the vicinity of the supply hole 24 and the vicinity of the discharge hole 26 of the electrode catalyst layer can be diffused. It is possible to favorably reduce variations in gas concentration.

  Therefore, as described above, even if the gas is supplied along the stacking direction in order to satisfactorily supply the gas to the electrolyte membrane / electrode structure 12, the gas concentration varies in the in-plane direction of the electrode catalyst layer. This can be suppressed and the electrochemical reaction in the entire electrode catalyst layer can be promoted. This makes it possible to improve the power generation efficiency of the fuel cell 10.

  On the other hand, of the gases supplied to the electrolyte membrane / electrode structure 12 from the supply holes 24, the remaining gas not consumed by the electrochemical reaction flows into the gas discharge passage 52 through the discharge holes 26, The gas is discharged from the gas discharge port 44 to the outside of the separator 14 through the discharge opening 56 and the gas discharge communication passage 46. As a result, gas can be satisfactorily supplied to the electrolyte membrane / electrode structure 12.

  Further, in this fuel cell 10, the separator 14 has the plate member 20 and the groove plate member 22, and the supply hole 24 and the discharge hole 26 provided in the plate member 20 and the gas supply provided in the groove plate member 22. The gas supply channel 50 and the gas exhaust channel 52 are formed by overlapping the channel groove 32 and the gas exhaust channel 34. As a result, the separator 14 having the plurality of gas supply passages 50 and the gas discharge passages 52 can be easily obtained with a simple configuration, and in turn, the manufacturing cost of the fuel cell 10 can be reduced. .

  The present invention is not particularly limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention.

  For example, in the above embodiment, the second line segment L2, which is the length between the discharge holes 26 in the same gas discharge channel 52, is the long side, and the gas supply channel 50 is sandwiched between different gas discharge channels 52. Although the first line segment L1 which is the length between the discharge holes 26 is the short side, conversely, the first line segment L1 may be longer than the second line segment L2. Alternatively, if the position of the supply hole 24 is a position where it is possible to sufficiently reduce the variation in the gas concentration between the vicinity of the supply hole 24 and the vicinity of the discharge hole 26, the intersection of the diagonal lines of the square S by the discharge hole 26. You may deviate from it.

  Further, in the above-described embodiment, both the supply hole 24 and the discharge hole 26 are circular in plan view, but the shapes of the supply hole 24 and the discharge hole 26 are not particularly limited. For example, only one of the supply hole 24 and the discharge hole 26 may be circular in plan view, and the other may be polygonal in plan view. Further, both the supply hole 24 and the discharge hole 26 may be polygonal in plan view.

  Furthermore, in the above-described embodiment, the separator 14 has the plate member 20 and the groove plate member 22, but the invention is not particularly limited to this. For example, the separator 14 is formed of separate members. You may have the gas supply flow path 50 and the gas discharge flow path 52.

  The experimental results according to the present invention will be shown below. In this experiment, a separator in which four discharge holes were arranged around one supply hole at the same distance (8.5 mm) from the supply hole and the positions thereof were the vertices of a long (square) square, A plurality of (regular) squares having different length ratios of the short side and the long side were prepared, unit cells of the fuel cell were prepared, and the performance of the fuel cell due to the difference in the length ratio was verified. The length ratios are four types of 1.0, 1.2, 1.4, and 1.6, and both the supply hole and the discharge hole have a circular shape with a diameter of 0.5 mm in plan view.

  Hydrogen gas was supplied as a fuel gas and air was supplied as an oxidant gas to each of the four types of unit cells to generate power and measure the voltage. The results are shown in FIG.

  From FIG. 3, it can be seen that the cell voltage tends to decrease as the length ratio increases from one. Further, in the approximate expression of the characteristics shown in FIG. 3, the ratio at the inflection point (the point where the second derivative becomes 0) was 1.33. That is, if the ratio of the length of the long side to the length of the short side is in the range of 1.00 to 1.33, it can be said that a good cell voltage is exhibited.

  From the above, in the fuel cell according to this embodiment in which the ratio of the length of the long side to the length of the short side is 1.00 to 1.33, the gas concentration varies in the in-plane direction of the electrode catalyst layer. Since the gas can be satisfactorily supplied and the electrochemical reaction can be promoted while suppressing this, the power generation efficiency can be improved.

10 ... Fuel cell 12 ... Electrolyte membrane / electrode structure 14 ... Separator 20 ... Plate member 22 ... Groove plate member 24 ... Supply hole 26 ... Discharge hole 32 ... Gas supply flow path groove 34 ... Gas discharge flow path groove 40 ... Gas supply Port 42 ... Gas supply communication path 44 ... Gas discharge port 46 ... Gas discharge communication path 50 ... Gas supply flow path 52 ... Gas discharge flow path 54 ... Supply opening 56 ... Discharge opening S ... Square

Claims (3)

A fuel cell comprising a separator facing an electrolyte membrane / electrode structure,
The separator is
A supply opening is provided at one end of which is closed and a gas is supplied at the other end, and a supply hole for discharging the gas supplied from the supply opening is provided at a predetermined interval on a side wall facing the electrolyte membrane / electrode structure. A plurality of gas supply channels,
A discharge opening for discharging the gas is provided at one end and the other end is provided, and a discharge hole into which the gas discharged from the supply hole flows is provided at a predetermined interval on a side wall facing the electrolyte membrane / electrode structure. A plurality of gas discharge channels,
A plate member integrally forming the side wall facing the electrolyte membrane / electrode structure of each of the plurality of gas supply channels and the gas discharge channels;
By stacking the plate members, a plurality of gas supply flow channels and gas discharge flow channels constituting the gas supply flow channel and the gas discharge flow channel groove plate member alternately arranged in parallel, Equipped with
A plurality of the gas supply passages and the gas discharge passages are alternately arranged in parallel,
A fuel cell, characterized in that the ratio of the length of the long side to the length of the short side is 1.00 to 1.33 in a rectangle formed by the four discharge holes adjacent to one supply hole. The fuel cell according to claim 1,
The fuel cell is characterized in that the supply holes are arranged at positions of intersections of the diagonal lines of the rectangle. The fuel cell according to claim 1 or 2,
At least one of the supply hole and the discharge hole has a circular shape in a plan view.

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