JP2018022614A - Fuel battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel battery that exhibits excellent power generation efficiency since it is able to supply gas to a membrane electrode assembly satisfactorily and, moreover, is able to hinder variation in gas concentration in the direction of inside of a face of an electrode catalyst layer.SOLUTION: In a separator 14 of a fuel battery 10, a gas supply passage 50 and a gas discharge passage 52 are alternately provided in parallel. The gas supply passage 50 is closed at one end and has a supply opening 54 for supplying gas at the other end. A plurality of supply holes 24 for discharging the gas supplied from the supply opening 54 are provided at predetermined intervals on a side wall facing a membrane electrode assembly 12. The gas discharge passage 52 is closed at one end and has a discharge opening 56 for discharging gas at the other end. A plurality of discharge holes 26 into which gas discharged from the supply holes 24 flows are provided at predetermined intervals on the side wall facing the membrane electrode assembly 12. The ratio of a short side to a long side of a square S defined by four discharge holes 26 adjacent to one supply hole 24 is 1.00 to 1.33.SELECTED DRAWING: Figure 2

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) with a pair of separators (for example, Patent Document 1). In the electrolyte membrane / electrode structure, an electrode catalyst layer provided with a catalyst and a gas diffusion layer for supplying fuel gas and oxidant gas to the electrode catalyst layer are laminated on both sides of an electrolyte membrane made of an electrolyte polymer. Composed.

  The separator is provided with a gas flow path. 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. An electrochemical reaction occurs in the electrode catalyst layer, and power generation is performed.

  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, gas diffusion from the gas flow path is hindered. There is a risk that it will be. 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. As a result, there is a concern that the power generation efficiency of the fuel cell is lowered.

  Therefore, for example, Patent Document 2 discloses 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, the separator is provided with a plurality of rectangular gas supply passages and gas discharge passages that are closed at one end in the extending direction and opened at the other end. Rectangular supply holes and discharge holes are respectively provided on the side walls of the gas supply flow path and the gas discharge flow path facing the gas diffusion layer.

  In this way, by supplying gas from the opening at the other end to the gas supply channel closed at one end and increasing the internal pressure, almost all of the gas supplied to the gas supply channel is passed through the supply hole. Thus, it can be supplied along the stacking direction of the electrolyte membrane / electrode structure. Of the gas supplied from the supply hole to the electrolyte membrane / electrode structure in this way, the remaining gas that has not been consumed by the electrochemical reaction in the electrode catalyst layer is passed through the discharge hole to the gas discharge channel. It flows in and is discharged from the opening of the discharge channel.

Japanese Patent No. 5042618 JP 2006-114414 A

  As described above, when 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 larger 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 Therefore, it becomes difficult to cause an electrochemical reaction sufficiently in the vicinity of the discharge hole. That is, there is a concern that the power generation efficiency of the fuel cell may be reduced due to variations in the gas concentration generated in the in-plane direction of the electrode catalyst layer.

  The present invention solves this type of problem, because it can supply gas to the electrolyte membrane / electrode structure well, and it is possible to suppress variation 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.

  To achieve the above object, the present invention provides a fuel cell comprising a separator facing an electrolyte membrane / electrode structure, wherein the separator has a supply opening that is closed at one end and supplied with gas at the other end. A gas supply flow path in which a plurality of supply holes for discharging the gas supplied from the supply opening are provided at predetermined intervals on a side wall facing the electrolyte membrane / electrode structure; A gas exhaust 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 is provided at a predetermined interval on a side wall facing the electrolyte membrane / electrode structure. A plurality of the gas supply flow paths and the gas discharge flow paths are alternately arranged in parallel, and in the square formed by the four discharge holes adjacent to the one supply hole, the long side with respect to the short side is provided. Length ratio is Characterized in that it is a .00～1.33.

  In the fuel cell according to the present invention, the gas discharged from the supply hole by increasing the internal pressure of the gas supply flow path by supplying gas from the supply opening at the other end to the gas supply flow path closed at one end. The pressure of can be increased. Thus, for example, almost all of the gas supplied to the gas supply flow path can be removed from the electrolyte membrane / electrode regardless of whether or not the water produced by the electrochemical reaction in the electrode catalyst layer is retained in the gas diffusion layer. It can be satisfactorily supplied along the stacking direction of the structures.

  At this time, the arrangement of the supply holes is adjusted so that the ratio of the length of the long side to the short side is 1.00 to 1.33 in the square formed by the four supply holes adjacent to the one discharge hole. ing. Here, even when the ratio of the length is 1.00 and the square is a square, for convenience of explanation, one side of the square is referred to as a short side and the other side is referred to as a long side. That is, the short side and the long side may have the same length. Since the gas discharged from the supply hole diffuses in the electrolyte membrane / electrode structure as a spherical wave, the gas generated in the in-plane direction of the electrode catalyst layer by arranging the supply hole to satisfy the above conditions Variation in density can be sufficiently reduced. That is, it is possible to effectively cause an electrochemical reaction in the electrode catalyst layer.

  From the above, according to the fuel cell according to the present invention, the electrochemical reaction is promoted by supplying the gas satisfactorily while suppressing the variation of the gas concentration in the in-plane direction with respect to the electrode catalyst layer. Therefore, power generation efficiency can be improved.

  In the above fuel cell, it is preferable that the supply hole is disposed at the intersection of the rectangular diagonal lines. In this case, the variation in gas concentration between the vicinity of the supply hole and 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 increased. Can be further improved.

  In the 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 circulated more smoothly through the supply hole or the discharge hole, and the electrochemical reaction in the electrode catalyst layer can be promoted. It becomes 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 walls facing the electrolyte membrane / electrode structure of each of the plurality of gas supply channels and the gas discharge channels, and the plate member includes A plurality of gas supply flow channel grooves and gas discharge flow channel grooves constituting the gas supply flow channel and the gas discharge flow channel, and a groove plate member in which a plurality of gas discharge flow channel grooves are alternately arranged. preferable. 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 thus the manufacturing cost of the fuel cell can be reduced.

  In the fuel cell according to the present invention, the supply is made with respect to a gas supply channel in which one end is closed, a supply opening is provided at the other end, and a plurality of supply holes are provided in a side wall facing the electrolyte membrane / electrode structure. Gas is supplied from 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, so almost all of the gas supplied to the gas supply channel is transferred to the electrolyte membrane / electrode structure. , Can be supplied well along the stacking direction.

  Moreover, in the square by the four said discharge holes adjacent to the said one supply hole, it arrange | positions so that the ratio of the length of the long side with respect to a short side may be set to 1.00-1.33. For this reason, as described above, even if gas is supplied from the supply hole along the stacking direction of the electrolyte membrane / electrode structure, the variation in gas concentration in the in-plane direction of the electrode catalyst layer is suppressed, An electrochemical reaction can be effectively generated. As a result, the power generation efficiency of the fuel cell can be improved.

It is a principal part disassembled perspective view of the fuel cell which concerns on embodiment of this invention. It is a front view by the side of the plate member of the separator of FIG. It is a graph which shows the relationship between ratio (long side / short side) of 2nd line segment L2 (long side) with respect to 1st line segment L1 (short side), and the cell voltage of a fuel cell.

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

  As shown in FIG. 1, the unit cell of the fuel cell 10 according to the present 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. In addition, since the separator not shown is comprised in the substantially same manner as the separator 14, description of a separator not shown is abbreviate | omitted with description of the separator 14 below.

  The electrolyte membrane / electrode structure 12 includes an electrolyte membrane made of an electrolyte polymer, an electrode catalyst layer serving as a reaction field for electrode reaction on both surfaces of the electrolyte membrane, and a fuel gas and an oxidant gas on each of the electrode catalyst layers. And a gas diffusion layer that diffuses and supplies a gas such as the like. That is, an electrode catalyst layer is disposed on both sides of the electrolyte membrane, and a gas diffusion layer is disposed on both sides of the electrode catalyst layer. Note 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 is subjected to anticorrosion surface treatment, carbon, etc., and the plate member 20 and the groove plate A member 22 is provided. The plate member 20 faces the gas diffusion layer of the electrolyte membrane / electrode structure 12, and a plurality of supply holes 24 and discharge holes 26 are formed therethrough as will be described later.

  The groove plate member 22 includes a plurality of gas supply flow channel grooves 32 and gas discharge flow channel grooves 34 that extend along the short side direction of the groove plate member 22. A plurality of lines are alternately arranged at intervals. A gas supply port 40 is provided on one end side in the short side direction of the groove plate member 22, and the gas supply port 40 extends along the long side direction of the groove plate member 22. And communicate with each of the plurality of gas supply channel grooves 32. On the other hand, a gas discharge port 44 is provided on the other end side in the short side direction of the groove plate member 22, and the gas discharge port 44 extends along the long side direction of the groove plate member 22. The plurality of gas discharge passage grooves 34 communicate with each other through 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. It is fixed by positioning. As a result, a gas supply channel 50 is formed between the gas supply channel groove 32 and the plate member 20, and a gas discharge channel 52 is formed between the gas discharge channel groove 34 and the plate member 20.

  That is, the side walls of the gas supply channel 50 and the gas discharge channel 52 facing the electrolyte membrane / electrode structure 12 are integrally formed by the plate member 20. In addition, the gas supply channel 50 and the gas discharge channel 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 channel 50 is provided with a supply opening 54 that is closed at one end and communicates with the gas supply port 40 through the gas supply communication path 42 at the other end. For this reason, a gas such as a fuel gas or an oxidant gas (hereinafter also simply referred to as a gas) supplied from the gas supply port 40 to the gas supply communication passage 42 flows into the gas supply channel 50 through the supply opening 54. To do. The gas discharge passage 52 is provided with a discharge opening 56 that 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 channel 52 flows to the gas discharge communication path 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 is, for example, a circular shape having a diameter of approximately 0.1 to 3.0 mm in plan view, and has a predetermined interval (up to 20 mm) in the extending direction of each of the plurality of gas supply flow paths 50. A plurality are arranged. As a result, the gas in the gas supply channel 50 can be discharged along the stacking direction of the electrolyte membrane / electrode structure 12 through the supply hole 24.

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

  That is, the supply holes 24 and the discharge holes 26 are arranged on the plate member 20 in lattice points. Specifically, the long side (the first line segment L1 in FIG. 2) with respect to the short side (first line segment L1 in FIG. 2) that surrounds one supply hole 24 and has the four discharge holes 26, 26, 26, 26 adjacent to each other as apexes. 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 that is an intersection of diagonal lines of the square S. Here, even when the ratio of the length is 1.00 and the square S is a square, for convenience of explanation, one side (first line segment L1) of the square S is referred to as a short side, and the other side ( The second line segment L2) is referred to as the long side. That is, the short side and the long side may have the same length.

  Basically, the effects 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 path 42. This gas is introduced into the gas supply channel 50 via the supply opening 54. 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. For this reason, the gas whose pressure is increased in the gas supply channel 50 is discharged from the supply hole 24. As a result, for example, almost all of the gas supplied to the gas supply flow channel 50 is supplied from the supply hole 24 to the electrolyte membrane, regardless of whether the generated water or the like accompanying the electrochemical reaction is retained in the gas diffusion layer. It can be satisfactorily supplied along the stacking direction of the electrode structure 12.

  Thus, the gas 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 falls within the above range, and the supply to the discharge holes 26, 26, 26, and 26 is performed as described above. A hole 24 is provided. Further, the supply hole 24 and the discharge hole 26 are circular in plan view. By these, the gas that is a spherical wave can be smoothly circulated through the electrolyte membrane / electrode structure 12 and effectively diffused, so that the gas is provided between the vicinity of the supply hole 24 and the vicinity of the discharge hole 26 of the electrode catalyst layer. Variations in gas concentration can be reduced satisfactorily.

  Therefore, as described above, in order to supply gas to the electrolyte membrane / electrode structure 12 satisfactorily, even if gas is supplied along the stacking direction, 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. As a result, the power generation efficiency of the fuel cell 10 can be improved.

  On the other hand, of the gas supplied from the supply hole 24 to the electrolyte membrane / electrode structure 12, the remaining gas that has not been consumed by the electrochemical reaction flows into the gas discharge passage 52 through the discharge hole 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. Thereby, the gas can be satisfactorily supplied to the electrolyte membrane / electrode structure 12.

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

  In addition, this invention is not specifically limited to above-described embodiment, A various deformation | transformation is possible in the range which does not deviate from the summary.

  For example, in the above embodiment, the second line segment L2 that is the length between the discharge holes 26 in the same gas discharge flow path 52 is a long side, and the gas supply flow path 50 is sandwiched between different gas discharge flow paths 52. The first line segment L1 which is the length between the discharge holes 26 is a short side, but conversely, the first line segment L1 can be longer than the second line segment L2. Alternatively, if the position of the supply hole 24 is a position that can sufficiently reduce the variation in 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. May deviate from.

  In the above 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.

  Further, in the above-described embodiment, the separator 14 has the plate member 20 and the groove plate member 22, but is not particularly limited thereto. For example, the separator 14 is formed from a separate member. The gas supply channel 50 and the gas discharge channel 52 may be provided.

  Hereinafter, experimental results according to the present invention will be shown. In this experiment, a separator in which four discharge holes are arranged around one supply hole so as to be equidistant (8.5 mm) from the supply hole and the position thereof is a vertex of a long (positive) square, (Correct) A plurality of cells having different ratios of the short side and the long side of the square were prepared, and unit cells of the fuel cell were prepared respectively, and the performance of the fuel cell according to the difference in the length ratio was verified. There are four types of length ratios of 1.0, 1.2, 1.4, and 1.6. Both the supply hole and the discharge hole have a circular shape with a diameter of 0.5 mm in plan view.

  For four types of unit cells, hydrogen gas was supplied as a fuel gas, and air was supplied as an oxidant gas to generate power, and the voltage was measured. The results are shown in FIG.

  It can be seen from FIG. 3 that the cell voltage tends to decrease as the length ratio increases from 1. Further, in the approximate expression of the characteristic shown in FIG. 3, the ratio at the inflection point (the point at which the second derivative becomes 0) was 1.33. That is, if the ratio of the length of the long side to 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 short side is 1.00 to 1.33, the gas concentration varies in the in-plane direction with respect to the electrode catalyst layer. Since the gas can be supplied satisfactorily and the electrochemical reaction can be promoted while suppressing this, the power generation efficiency can be improved.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell 12 ... Electrolyte membrane electrode assembly 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 passage 44 ... Gas discharge port 46 ... Gas discharge communication passage 50 ... Gas supply passage 52 ... Gas discharge passage 54 ... Supply opening 56 ... Discharge opening S ... Square

Claims (4)

A fuel cell comprising a separator facing the electrolyte membrane / electrode structure,
The separator is
A supply opening for closing one end and supplying gas to the other end is provided, and a supply hole for discharging the gas supplied from the supply opening is spaced apart from a side wall facing the electrolyte membrane / electrode structure. A plurality of gas supply passages;
One end is closed and the other end is provided with a discharge opening for discharging the gas, and the discharge hole into which the gas discharged from the supply hole flows is spaced from the side wall facing the electrolyte membrane / electrode structure at a predetermined interval. A plurality of gas discharge passages provided,
A plurality of the gas supply flow paths and the gas discharge flow paths are alternately arranged in parallel,
A fuel cell, wherein a ratio of a length of a long side to a short side is 1.00 to 1.33 in a square formed by four discharge holes adjacent to one supply hole. The fuel cell according to claim 1, wherein
The fuel cell according to claim 1, wherein the supply hole is disposed at an intersection of the rectangular diagonal lines. 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. The fuel cell according to any one of claims 1 to 3,
The separator is
A plate member integrally forming the side walls facing the electrolyte membrane / electrode structure of each of the plurality of gas supply channels and the gas discharge channels;
A plurality of gas supply flow channel grooves and gas discharge flow channel grooves that constitute the gas supply flow channel and the gas discharge flow channel, and a plurality of the gas supply flow channel grooves alternately arranged in parallel;
A fuel cell comprising:

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