fuel cell
The fuel cell design with grooves on the separator's side portions addresses water retention issues by facilitating efficient water drainage, enhancing power generation performance through capillary force and reaction gas flow.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- TOYOTA JIDOSHA KK
- Filing Date
- 2024-11-29
- Publication Date
- 2026-06-10
AI Technical Summary
Retention of generated water in a fuel cell inhibits the flow of reaction gas, reducing power generation performance, necessitating improved drainage performance.
The fuel cell design incorporates grooves on the separator's side portions extending from the rib to the bottom surface, with varying widths and orientations to facilitate water drainage, utilizing capillary force and reaction gas flow for efficient water removal.
The grooves effectively discharge generated water, enhancing drainage performance even at low reaction gas velocities and with materials of varying hydrophilicity, thereby improving power generation efficiency.
Smart Images
Figure 2026094814000001_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to fuel cell.
Background Art
[0002] Various techniques related to the structure of fuel cells have been proposed. For example, Patent Document 1 discloses a separator having concavo-convex portions through which reaction gas flows. In this separator, by curving the convex portions constituting the concavo-convex portions in the thickness direction, the drainage performance of the generated water accumulated between the convex portions and the gas diffusion layer is improved.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] Retention of generated water in a fuel cell may inhibit the flow of reaction gas, which may reduce the power generation performance. Further improvement in drainage performance is required.
Means for Solving the Problems
[0005] [[ID=4j]] This disclosure can be realized in the following forms.
[0006] (1) According to one embodiment of the present disclosure, a fuel cell is provided comprising a membrane electrode assembly, a pair of gas diffusion layers provided so as to sandwich the membrane electrode assembly, and a pair of separators provided so as to sandwich the pair of gas diffusion layers. At least one of the pair of separators has on the surface facing the gas diffusion layer a flow channel portion through which a reaction gas flows, and a rib portion provided adjacent to the flow channel portion and in contact with the gas diffusion layer, the flow channel portion having a bottom surface away from the gas diffusion layer and a side portion connecting the bottom surface and the rib portion, the side portion having a groove extending from the connection portion with the rib portion toward the bottom surface. In this type of fuel cell, grooves are provided on the sides, extending from the connection point with the rib section to the bottom surface. This allows generated water to be discharged from the gas diffusion layer through the grooves, thereby improving drainage performance. (2) In the fuel cell cell of the above form, the width of the groove in the part close to the rib part may be narrower than the width of the groove in the part close to the bottom surface. In this type of fuel cell, the width of the groove near the rib is narrower than the width near the bottom, allowing the generated water accumulated between the rib and the gas diffusion layer to be guided into the groove by capillary force. This improves drainage performance by utilizing capillary force, even when the flow velocity of the reaction gas supplied to the fuel cell is low. (3) In the fuel cell cell of the above form, the width of the groove in the part closest to the bottom surface may be narrower than the width of the groove in the part closest to the rib. In this type of fuel cell, the width of the groove near the rib is wider than the width near the bottom, allowing the generated water accumulated between the rib and the gas diffusion layer to be guided to the relatively wider part of the groove. This improves drainage performance even when the separator is made of a material with relatively low hydrophilicity and the resulting capillary force is relatively small. (4) In the fuel cell cell of the above form, the width of the groove may be constant. In this type of fuel cell, the groove width is constant, making it easier to create grooves compared to configurations where the groove width varies depending on the location. (5) In the fuel cell cell of the above form, the groove may be inclined from the rib side toward the bottom side in the direction through which the reaction gas flows. In this type of fuel cell, the grooves are inclined from the rib side towards the bottom side in the direction of reaction gas flow, making it easier to discharge the generated water in the grooves to the outside of the fuel cell by the flow of reaction gas. This improves the drainage performance of the fuel cell. [Brief explanation of the drawing]
[0007] [Figure 1] This is a perspective view of a fuel cell in which a fuel cell cell according to one embodiment of the present disclosure is used. [Figure 2] This is a plan view of the separator. [Figure 3] This is a cross-sectional view of a fuel cell cut at the position corresponding to line III-III in Figure 2. [Figure 4] This is a perspective view of a separator used in a fuel cell cell of the second embodiment. [Figure 5] This is a perspective view of a separator used in a fuel cell cell of the third embodiment. [Figure 6] This is a perspective view of a separator used in a fuel cell cell of the fourth embodiment. [Modes for carrying out the invention]
[0008] A. First Embodiment: <Configuration of Fuel Cell 100> Figure 1 is a perspective view of a fuel cell 100 in which a fuel cell cell 10 in one embodiment of the present disclosure is used. Figure 1 shows mutually orthogonal X, Y, and Z axes. Figure 2 is a plan view of the separator 200. The lower part of Figure 2 shows an enlarged and schematic representation of the flow path section 210 and rib section 220, which will be described later. Figure 3 is a cross-sectional view of the fuel cell cell 10 cut at a position corresponding to the line III-III in Figure 2. The fuel cell 100 is used, for example, as a power source for an electric vehicle. As shown in Figure 1, the fuel cell 100 comprises a cell stack 110 and a pair of terminal plates 120, 130.
[0009] The cell stack 110 is composed of a plurality of fuel cell cells 10 stacked in the Z direction. The fuel cell cells 10 are solid polymer fuel cells that generate electricity using reaction gases. The reaction gases are, for example, oxygen as an oxidizing gas and hydrogen as a fuel gas. The fuel cell cells 10 have a rectangular plate-like external shape. The detailed configuration of the fuel cell cells 10 will be described later.
[0010] Each of the pair of terminal plates 120 and 130 is positioned at both ends of the cell stack 110 in the stacking direction. Each terminal plate 120 and 130 is made of a conductive material such as aluminum or copper. Each terminal plate 120 and 130 is used to extract the electricity generated by the fuel cell cell 10 to the outside.
[0011] The fuel cell cell 10 has oxidizer gas manifolds 11a and 11b, refrigerant manifolds 12a and 12b, and fuel gas manifolds 13a and 13b. Each of these manifolds is composed of manifold holes formed in terminal plates 120 and 130 and a separator 200, which will be described later. The oxidizer gas manifold 11a is used to supply oxidizer gas to the fuel cell cell 10. The oxidizer gas manifold 11b is used to discharge oxidizer gas from the fuel cell cell 10. The refrigerant manifold 12a is used to supply refrigerant to the fuel cell cell 10. The refrigerant manifold 12b is used to discharge refrigerant from the fuel cell cell 10. The fuel gas manifold 13a is used to supply fuel gas to the fuel cell cell 10. The fuel gas manifold 13b is used to discharge fuel gas from the fuel cell cell 10.
[0012] <Configuration of fuel cell cell 10> As shown in Figure 3, the fuel cell cell 10 comprises a membrane electrode assembly 300, a pair of gas diffusion layers 400 provided so as to sandwich the membrane electrode assembly 300, and a pair of separators 200 provided so as to sandwich the pair of gas diffusion layers 400.
[0013] The membrane electrode assembly 300 is composed of an electrolyte membrane, an anode catalyst layer bonded to one side of the electrolyte membrane, and a cathode catalyst layer bonded to the other side of the electrolyte membrane. The electrolyte membrane is a solid polymer membrane having proton conductivity. The electrolyte membrane is, for example, an ion exchange membrane made of a fluororesin. The anode catalyst layer includes a catalyst that promotes the chemical reaction of the fuel gas and carbon particles supporting the catalyst. The cathode catalyst layer includes a catalyst that promotes the chemical reaction of the oxidizer gas and carbon particles supporting the catalyst.
[0014] The gas diffusion layer 400 uniformly diffuses the reaction gas flowing through the flow path portion 210 described later to the membrane electrode assembly 300. The gas diffusion layer 400 is composed of a porous body. The porous body is manufactured by, for example, a metal or a carbon material. The gas diffusion layer 400 is provided in parallel with the membrane electrode assembly 300.
[0015] The separator 200 suppresses the leakage of the reaction gas from the fuel cell 10. The separator 200 is composed of, for example, a metal material such as aluminum or titanium. As shown in FIG. 2, the separator 200 has an external shape of a rectangular plate. Six manifold holes 221a, 221b, 222a, 222b, 223a, 223b are formed in the separator 200. The manifold hole 221a is a part of the oxidant gas manifold 11a, the manifold hole 221b is a part of the oxidant gas manifold 11b, the manifold hole 222a is a part of the refrigerant manifold 12a, the manifold hole 222b is a part of the refrigerant manifold 12b, the manifold hole 223a is a part of the fuel gas manifold 13a, and the manifold hole 223b is a part of the fuel gas manifold 13b.
[0016] As shown in FIG. 3, the separator 200 has a plurality of flow path portions 210 and rib portions 220 provided so as to be sandwiched between the respective flow path portions 210 on the surface on the gas diffusion layer 400 side. The reaction gas flows through each flow path portion 210. More specifically, as shown in FIG. 2, the reaction gas is supplied to each flow path portion 210 from the manifold hole 221a or the manifold hole 223a, and is discharged from each flow path portion 210 through the manifold hole 221b or the manifold hole 223b. At least a part of the reaction gas flowing through each flow path portion 210 is supplied to the gas diffusion layer 400.
[0017] As shown in FIG. 3, each flow path portion 210 has a bottom surface 211 and a pair of side portions 212. The bottom surface 211 is separated from the gas diffusion layer 400. Also, the bottom surface 211 is provided parallel to the gas diffusion layer 400. The pair of side portions 212 connect the bottom surface 211 and a rib portion 220 described later. Each of the pair of side portions 212 is connected to both ends in the width direction (X direction) of the bottom surface 211. Each of the pair of side portions 212 is inclined so that the width of the flow path portion 210 becomes wider from the bottom surface 211 side toward the gas diffusion layer 400 side. Therefore, the flow path portion 210 has a U-shaped cross section parallel to the width direction. Note that the detailed configuration of the side portion 212 will be described later.
[0018] The rib portion 220 is provided between each of the flow path portions 210. It can also be said that the rib portion 220 is adjacent to the flow path portion 210. The rib portion 220 has a flat surface. The rib portion 220 is provided parallel to the gas diffusion layer 400 and is in contact with the gas diffusion layer 400. Therefore, the load applied in the thickness direction of the separator 200 is applied to the gas diffusion layer 400 via the rib portion 220. Each of both ends in the width direction of the rib portion 220 is connected to the side portion 212 of each of the two flow path portions 210 provided so as to sandwich the rib portion 220.
[0019] Due to the repeated provision of the above-described flow path portions 210 and rib portions 220, in a cross section orthogonal to the direction in which the reaction gas shown in FIG. 3 flows, the separator 200 has a concavo-convex shape.
[0020] <Detailed Configuration of Side Portion 212 and Groove GR> As shown in the lower part of Figure 2, the side portion 212 in this disclosure is provided with a plurality of grooves GR. Specifically, each groove GR is provided from the connection portion of the side portion 212 with the rib portion 220 toward the bottom surface 211. Each groove GR is arranged along the longitudinal direction (Y direction) of the flow channel portion 210. In this embodiment, the width of the groove GR in the portion closer to the rib portion 220 is narrower than the width of the portion closer to the bottom surface 211. It can also be said that each groove GR has a convex planar shape in which the width widens from the rib portion 220 side toward the bottom surface 211 side. The narrowest width of the groove GR is, for example, 1 mm to 2 mm. The widest width of the groove GR is, for example, 5 mm to 8 mm. The depth of the groove is, for example, 1 mm to 5 mm. The length of the groove is, for example, 3 mm to 10 mm.
[0021] Each groove GR is used for draining water from the gas diffusion layer 400 to the flow channel 210. In the fuel cell cell 10, water is generated on the cathode side by the reaction of the oxidizer gas. In addition, the water generated on the cathode side may move beyond the membrane electrode assembly 300 to the anode side. If the generated water accumulates, it will obstruct the flow of the reaction gas and reduce the power generation efficiency. For this reason, it is preferable that the generated water be discharged to the outside of the fuel cell cell 10 via the flow channel 210. However, generated water may accumulate in the contact portion AR1 between the rib portion 220 and the gas diffusion layer 400 shown in Figure 3. The generated water accumulated in the contact portion AR1 obstructs the movement of reaction gas between the flow channels 210 and the movement of reaction gas in the gas diffusion layer 400. As a result, the reaction gas is prevented from spreading throughout the entire membrane electrode assembly 300. Here, as disclosed herein, by providing a groove GR extending from the connection portion of the side portion 212 with the rib portion 220, the generated water accumulated between the rib portion 220 and the gas diffusion layer 400 can be discharged into the flow channel portion 210. The generated water discharged into the flow channel portion 210 is guided to the outside of the fuel cell cell 10 by the flow of the reaction gas.
[0022] According to the fuel cell cell 10 of the first embodiment described above, the side portion 212 is provided with a plurality of grooves GR extending from the connection portion with the rib portion 220 toward the bottom surface 211, so that generated water can be discharged from the gas diffusion layer 400 through each groove GR. This improves the drainage performance.
[0023] Furthermore, according to the fuel cell cell 10 of the first embodiment, the width of the groove GR near the rib portion 220 is narrower than the width of the groove near the bottom surface 211, so that the generated water accumulated between the rib portion 220 and the gas diffusion layer 400 can be guided into each groove GR by capillary force. As a result, even if the flow velocity of the reaction gas supplied to the fuel cell cell 10 is small, for example, the drainage performance can be improved by utilizing capillary force.
[0024] B. Second Embodiment: Figure 4 is a perspective view of the separator 200b used in the fuel cell of the second embodiment. Figure 4 shows a portion of the separator 200b at a position corresponding to the lower enlarged view in Figure 2. The separator 200b of the second embodiment has a different groove shape GRb than the groove GR in the separator 200 of the first embodiment. The other configurations of the fuel cell of the second embodiment are the same as those of the fuel cell 10 of the first embodiment, so their description is omitted.
[0025] As shown in Figure 4, the width of the groove GRb near the rib portion 220 is wider than the width of the groove near the bottom surface 211. It can also be said that the groove GRb has a convex planar shape in which the width narrows from the rib portion 220 side towards the bottom surface 211 side. The narrowest width of the groove GRb is, for example, 1 mm to 2 mm. The widest width of the groove GRb is, for example, 5 mm to 8 mm.
[0026] According to the fuel cell cell 10 of the second embodiment described above, the width of the groove GRb near the rib portion 220 is wider than the width of the groove near the bottom surface 211. Therefore, the generated water accumulated between the rib portion 220 and the gas diffusion layer 400 can be guided to the relatively wider portion of the groove GRb. As a result, even if the separator 200 is made of a material with relatively low hydrophilicity and the resulting capillary force is relatively small, the drainage performance can be improved.
[0027] C. Third Embodiment: Figure 5 is a perspective view of the separator 200c used in the fuel cell of the third embodiment. Figure 5 shows a portion of the separator 200c at a position corresponding to the lower enlarged view in Figure 2. The separator 200c of the third embodiment has a different groove shape GRc than the groove GR in the separator 200 of the first embodiment. The other configurations of the fuel cell of the third embodiment are the same as those of the fuel cell cell 10 of the first embodiment, so their description is omitted.
[0028] As shown in Figure 5, the width of the groove GRc is constant from the rib portion 220 side to the bottom surface 211 side. It can also be said that the groove GRc has a linear shape in plan view. The width of the groove GRc is, for example, 1 mm to 5 mm.
[0029] In the fuel cell of the third embodiment described above, the width of the groove GRc is constant from the rib portion 220 side to the bottom surface 211 side, so the groove GRc can be easily provided compared to a configuration in which the width of the groove varies depending on the part.
[0030] D. Fourth Embodiment: Figure 6 is a perspective view of the separator 200d used in the fuel cell of the fourth embodiment. Figure 6 shows a portion of the separator 200d at a position corresponding to the lower enlarged view in Figure 2. The separator 200d of the fourth embodiment has a different groove shape GRd than the groove GRc in the separator 200c of the third embodiment. The other components of the fuel cell of the fourth embodiment are the same as those of the fuel cell of the third embodiment, so their description is omitted.
[0031] As shown in Figure 6, the groove GRd is inclined in the direction through which the reaction gas flows, from the rib portion 220 side toward the bottom surface 211 side. In this embodiment, the reaction gas flows in the -Y direction.
[0032] Furthermore, the structure of groove GRd in the fourth embodiment may be used in combination with groove GR in the first embodiment or groove GRb in the second embodiment. That is, grooves of any shape may be inclined in the direction through which the reaction gas flows, from the rib portion 220 side toward the bottom surface 211 side.
[0033] According to the fourth embodiment of the fuel cell described above, the groove GRd is inclined in the direction through which the reaction gas flows, from the rib portion 220 side toward the bottom surface 211 side. This makes it easier to discharge the generated water in the groove GRd to the outside of the fuel cell by the flow of the reaction gas. This improves the drainage performance of the fuel cell.
[0034] E. Other embodiments: (E1) In the first embodiment described above, the groove GR had a convex plan view shape that widened from the rib portion 220 side towards the bottom surface 211 side, but the disclosure is not limited thereto. The groove GR may have any shape that widens from the rib portion 220 side towards the bottom surface 211 side. Also, in the second embodiment described above, the groove GRb had a convex plan view shape that narrowed from the rib portion 220 side towards the bottom surface 211 side, but the disclosure is not limited thereto. The groove GRb may have any shape that narrows from the rib portion 220 side towards the bottom surface 211 side.
[0035] (E2) In each of the above embodiments, multiple grooves GR, GRb, GRc, and GRd were provided, but the disclosure is not limited thereto. Only one groove GR, GRb, GRc, or GRd may be provided.
[0036] (E3) In the above embodiment, separators 200, 200b, 200c, and 200d were used in a fuel cell cell 10, but the disclosure is not limited thereto. Separators 200, 200b, 200c, and 200d may also be used in a water electrolysis cell.
[0037] (E4) In each of the above embodiments, the grooves GR, GRb, GRc, and GRd may be provided in only one of the pair of separators 200, 200b, 200c, and 200d.
[0038] (E5) In each of the above embodiments, the flow path section 210 may be formed as a so-called serpentine flow path that meanders back and forth between the manifold holes 221a, 223a on the reaction gas supply side and the manifold holes 221b, 223b on the reaction gas discharge side.
[0039] (E6) In each of the above embodiments, the rib portion 220 had a flat surface, but the disclosure is not limited thereto. The rib portion 220 may have a curved surface.
[0040] This disclosure is not limited to the embodiments described above, and can be implemented in various configurations without departing from its spirit. For example, the technical features in the embodiments corresponding to the technical features in each form described in the summary of the invention can be replaced or combined as appropriate in order to solve some or all of the above-described problems, or to achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be deleted as appropriate. [Explanation of symbols]
[0041] 10…Fuel cell, 11a,11b…Oxidizer gas manifold, 12a,12b…Refrigerant manifold, 13a,13b…Fuel gas manifold, 100…Fuel cell, 110…Cell stack, 120,130…Terminal plate, 200,200b,200c,200d…Separator, 210…Flow channel section, 211…Bottom surface, 212…Side section, 220…Rib section, 221a,221b,222a,222b,223a,223b…Manifold holes, 300…Membrane electrode assembly, 400…Gas diffusion layer, AR1…Contact section, GR,GRb,GRc,GRd…Groove
Claims
1. A fuel cell comprising a membrane electrode assembly, a pair of gas diffusion layers provided so as to sandwich the membrane electrode assembly, and a pair of separators provided so as to sandwich the pair of gas diffusion layers, At least one of the pair of separators has a flow channel portion through which the reaction gas flows on the surface facing the gas diffusion layer, and a rib portion provided adjacent to the flow channel portion and in contact with the gas diffusion layer, The flow channel portion has a bottom surface that is separated from the gas diffusion layer and a side portion that connects the bottom surface and the rib portion. The side portion is provided with a groove extending from the connection point with the rib portion toward the bottom surface. Fuel cell.
2. A fuel cell cell according to claim 1, Of the grooves, the width of the portion near the rib portion is narrower than the width of the portion near the bottom surface. Fuel cell.
3. A fuel cell cell according to claim 1, Of the grooves, the width of the portion near the rib portion is wider than the width of the portion near the bottom surface. Fuel cell.
4. A fuel cell cell according to claim 1, The width of the groove is constant in the fuel cell.
5. A fuel cell cell according to any one of claims 1 to 4, The groove is inclined from the rib side toward the bottom surface side in the direction through which the reaction gas flows. Fuel cell.