US-12620606-B2 - Power generation cell

Abstract

In a power generation cell, cathode flow field grooves forming a gas flow field of a cathode separator arranged to face an MEA are formed of first cathode flow field grooves blocked on an outlet side and second cathode flow field grooves blocked on an inlet side. The first cathode flow field grooves and the second cathode flow field grooves are arranged adjacent to each other in the flow field width direction.

Inventors

• Takuro Okubo
• Yoshihito Kimura

Assignees

• HONDA MOTOR CO., LTD.

Dates

Publication Date

20260505

Application Date

20230106

Priority Date

20220112

Claims (8)

1. 1 . A power generation cell comprising a membrane electrode assembly, a cathode separator and an anode separator, the membrane electrode assembly including an electrolyte membrane and electrodes arranged on both sides of the electrolyte membrane, the membrane electrode assembly being sandwiched by the cathode separator and the anode separator, wherein the cathode separator is made of a thin metal plate formed by press molding to have a wavy cross section, the cathode separator comprises: a cathode line ridges that protrude from the cathode separator, contact the membrane electrode assembly and extend in a flow direction of an oxygen-containing gas; and a plurality of cathode flow field grooves that are formed between the cathode line ridges and form an oxygen-containing gas flow field, the plurality of cathode flow field grooves has a wavy shape extending along a long-side direction, the wavy shape being defined by a plurality of regularly spaced rounded crests and rounded troughs in the long-side direction, the plurality of cathode flow field grooves comprise: a first cathode flow field groove that is connected to an oxygen-containing gas inlet and blocked on a downstream side in the flow direction of the oxygen-containing gas; and a second cathode flow field groove that is connected to an oxygen-containing gas outlet and blocked on an upstream side in the flow direction of the oxygen-containing gas, the first cathode flow field groove and the second cathode flow field groove are separated from each other by the cathode line ridges, the second flow field groove is arranged adjacent to the first flow field groove in the flow field width direction, the oxygen-containing gas outlet is arranged at one end in the flow field width direction, and of the second cathode flow field groove, a portion closest to the oxygen-containing gas outlet in the flow direction of the oxygen-containing gas is directed to the one end at which the oxygen-containing gas outlet is arranged in the flow field width direction.
2. 2 . The power generation cell according to claim 1 , wherein the anode separator comprises: anode line ridges that protrude from the anode separator, contact the membrane electrode assembly and extend in a flow direction of a fuel gas; and a plurality of anode flow field grooves that are formed between the anode line ridges and form a fuel gas flow field, and the plurality of anode flow field grooves comprises: a first anode flow field groove that is blocked on a downstream side in the flow direction of the fuel gas; a second anode flow field groove that is blocked on an upstream side in the flow direction of the fuel gas, and the second anode flow field groove is arranged adjacent to the first anode flow field groove in the flow field width direction.
3. 3 . The power generation cell according to claim 1 , wherein the plurality of cathode flow field grooves include a plurality of the first cathode flow field grooves blocked on the downstream side in the flow direction of the oxygen-containing gas and a plurality of the second cathode flow field grooves blocked on the upstream side in the flow direction of the oxygen-containing gas, and each first cathode flow field groove of the plurality of the first cathode flow field grooves and each second cathode flow field groove of the second cathode flow field grooves are alternately arranged with each other repeatedly in the flow field width direction.
4. 4 . The power generation cell according to claim 2 , wherein the plurality of anode flow field grooves include a plurality of the first anode flow field grooves blocked on the downstream side in the flow direction of the fuel gas, and a plurality of the second anode flow field grooves being blocked on the upstream side in the flow direction of the fuel gas, and each first anode flow field groove of the plurality of the first anode flow field grooves and each second anode flow field groove of the second anode flow field grooves are alternately arranged with each other repeatedly in the flow field width direction.
5. 5 . The power generation cell according to claim 1 , wherein a flow field cross-sectional area of the first cathode flow field groove is smaller than a flow field cross-sectional area of the second cathode flow field groove throughout the cathode flow field grooves.
6. 6 . The power generation cell according to claim 2 , wherein a flow field cross-sectional area of the first anode flow field groove is smaller than a flow field cross-sectional area of the second anode flow field groove.
7. 7 . The power generation cell according to claim 1 , wherein the first cathode flow field groove has a flow field cross-sectional area decreasing from upstream to downstream in the flow direction of the oxygen-containing gas, and the second cathode flow field groove has a flow field cross-sectional area increasing from upstream to downstream in the flow direction of the oxygen-containing gas.
8. 8 . The power generation cell according to claim 2 , wherein the first anode flow field groove has a flow field cross-sectional area decreasing from upstream to downstream in the flow direction of the fuel gas, and the second anode flow field groove has a flow field cross-sectional area increasing from upstream to downstream in the flow direction of the fuel gas.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2022-003183 filed on Jan. 12, 2022, the contents of which are incorporated herein by reference. BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a power generation cell of a fuel cell system. Description of the Related Art A fuel cell system is a power generation system that generates power by electrochemical reactions between a fuel gas such as hydrogen and an oxygen-containing gas such as air and does not discharge CO2. The fuel cell system may be mounted on a fuel cell vehicle or the like excellent in environmental performance. In addition, a regenerative fuel cell system using hydrogen and oxygen generated through energy storage by electrolysis of water can be used for output leveling of a solar power generation system or a wind power generation system having great fluctuations in output, and also contributes to expansion of use of sustainable renewable energy. For example, JP 2019-117721 A discloses a structure of a power generation cell of a fuel cell system. SUMMARY OF THE INVENTION A conventional power generation cell has a problem in that water generated by electrochemical reactions is likely to be retained inside a membrane electrode assembly (MEA). Therefore, a power generation cell having excellent drainage performance is desired. An object of the present invention is to solve the aforementioned problem. An aspect of the disclosure is a power generation cell comprising a membrane electrode assembly, a cathode separator and an anode separator, the membrane electrode assembly including a electrolyte membrane and electrodes arranged on both sides of the electrolyte membrane, the membrane electrode assembly being sandwiched by the cathode separator and the anode separator, wherein the cathode separator comprises cathode line ridges that protrude from the cathode separator, contact the membrane electrode assembly and extend in a flow direction of the oxygen-containing gas, and a plurality of cathode flow field grooves that are formed between the cathode line ridges and form an oxygen-containing gas flow field, the plurality of cathode flow field grooves comprise a first cathode flow field groove that is blocked on a downstream side in the flow direction of the oxygen-containing gas, and a second cathode flow field groove that is blocked on an upstream side in the flow direction of the oxygen-containing gas, and the second flow field groove is arranged adjacent to the first flow field groove in the flow field width direction. In the power generation cell of the above aspect, the first cathode flow field groove blocked on the downstream side in the flow direction of the oxygen-containing gas and the second cathode flow field groove blocked on the upstream side in the flow direction of the oxygen-containing gas are adjacent to each other in the flow field width direction. Thus, the oxygen-containing gas is caused to flow from the first cathode flow field groove toward the second cathode flow field groove in the membrane electrode assembly. The water generated in the membrane electrode assembly is efficiently removed not only by a passive process based on a water vapor diffusion process but also by an active process using a water transport phenomenon based on active fluid movement caused by the flow of the oxygen-containing gas. Therefore, the power generation cell is excellent in drainage performance, can prevent reaction inhibition due to flooding, and improves power generation efficiency. The above and other objects features and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective view of a power generation cell according to a first embodiment; FIG. 2 is a plan view of a first surface of the cathode separator shown in FIG. 1; FIG. 3A is an enlarged view of the vicinity of ends of the first cathode flow field groove and the second cathode flow field groove in the arrow B1 direction; FIG. 3B is an enlarged view of the vicinity of ends of the first cathode flow field groove and the second cathode flow field groove in the arrow B2 direction; FIG. 4 is a cross-sectional view illustrating the function of the cathode separator shown in FIG. 2; FIG. 5 is an enlarged view illustrating the fluid flow in the cathode separator shown in FIG. 2; FIG. 6 is an enlarged view of an anode separator according to a second embodiment in the vicinity of ends of a first anode flow field groove and a second anode flow field groove in the arrow B2 direction; FIG. 7 is a schematic view illustrating an arrangement of oxygen-containing gas flow field of a cathode separator according to a third emb