EP-4742331-A1 - FUEL CELL AND METHOD FOR MANUFACTURING FUEL CELL

Abstract

A fuel cell includes an anode separator and a cathode separator each including a coating on its surface. Each of the anode and cathode separators includes: a body; a coolant manifold configured to allow a coolant to flow therethrough; an intra-cell sealing portion that provides a seal between the anode and cathode separators within the fuel cell and that is provided by the body being bonded to the insulating sheet so as to surround the coolant manifold; and a sacrificial electrolytic corrosion portion disposed between the coolant manifold and the intra-cell sealing portion and including a plurality of exposed portions where a base material is exposed without being covered with the coating. The sacrificial electrolytic corrosion portion includes at least one of the exposed portions on a straight line connecting the coolant manifold and the intra-cell sealing portion.

Inventors

• TAKEHIRO, NAOKI

Assignees

• TOYOTA JIDOSHA KABUSHIKI KAISHA

Dates

Publication Date

20260513

Application Date

20250903

Claims (5)

1. A fuel cell comprising: a plate member including a membrane electrode gas diffusion layer assembly and an insulating sheet that holds an outer peripheral portion of the membrane electrode gas diffusion layer assembly; and an anode separator and a cathode separator that sandwich the plate member, the anode separator including a coating on a surface of the anode separator, and the cathode separator including a coating on a surface of the cathode separator; wherein: each of the anode separator and the cathode separator includes a body, a coolant manifold that is an opening in the body, the coolant manifold being configured to allow a coolant to flow through the coolant manifold, an intra-cell sealing portion that provides a seal between the anode separator and the cathode separator within the fuel cell, the intra-cell sealing portion being provided by the body being bonded to the insulating sheet so as to surround the coolant manifold, and a sacrificial electrolytic corrosion portion disposed between the coolant manifold and the intra-cell sealing portion, the sacrificial electrolytic corrosion portion including a plurality of exposed portions where a base material is exposed without being covered with the coating; and the sacrificial electrolytic corrosion portion includes at least one of the exposed portions on a straight line connecting the coolant manifold and the intra-cell sealing portion.
2. The fuel cell according to claim 1, wherein the sacrificial electrolytic corrosion portion includes the exposed portion on each of two or more concentric circles centered around the coolant manifold.
3. The fuel cell according to claim 1, wherein the sacrificial electrolytic corrosion portion includes the exposed portions at an interval of 10 µm or less.
4. A method for manufacturing a fuel cell, the method comprising: a plate preparation step of preparing a plate member including (1a) a membrane electrode gas diffusion layer assembly and (1b) an insulating sheet that holds an outer peripheral portion of the membrane electrode gas diffusion layer assembly; a base material preparation step of preparing a base material for an anode separator and a cathode separator, the base material including (2a) a body, (2b) a coolant manifold that is an opening in the body, the coolant manifold being configured to allow a coolant to flow through the coolant manifold, and (2c) an embossed portion disposed near the coolant manifold, the embossed portion including a plurality of protrusions protruding from the body; a surface treatment step of treating a surface of the base material to form a coating on the surface of the base material; a forming step of pressing on the base material with the coating to form each of the anode separator and the cathode separator into a predetermined shape; and an intra-cell sealing portion forming step of forming an intra-cell sealing portion by sandwiching the plate member between the anode separator and the cathode separator and bonding the insulating sheet to the body so as to surround the coolant manifold, the intra-cell sealing portion providing a seal between the anode separator and the cathode separator within the fuel cell, wherein the forming step includes an exposing step of forming a sacrificial electrolytic corrosion portion by stretching the protrusions using an external force applied by the pressing to rupture the coating on the protrusions, the sacrificial electrolytic corrosion portion including a plurality of exposed portions where the base material is exposed without being covered with the coating.
5. The method according to claim 4, wherein the protrusion protrudes from a surface of the body that faces the insulating sheet toward an opposite surface of the body from the surface that faces the insulating sheet.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present disclosure relates to fuel cells and methods for manufacturing a fuel cell. 2. Description of Related Art Conventionally, there has been known a fuel cell including an anode separator and a cathode separator that sandwich a membrane electrode gas diffusion layer assembly and an insulating sheet that holds an outer peripheral portion of the membrane electrode gas diffusion layer assembly (Japanese Unexamined Patent Application Publication No. 2023-168686 (JP 2023-168686 A)). In this fuel cell, each separator includes: a coolant manifold that allows a coolant to flow therethrough; and a sealing portion bonded to the insulating sheet to provide a seal between the anode separator and the cathode separator. Each separator further includes a sacrificial electrolytic corrosion portion. The sacrificial electrolytic corrosion portion is disposed between the coolant manifold and the sealing portion without being bonded to the insulating sheet. Since the sacrificial electrolytic corrosion portion is preferentially electrolytically corroded over the sealing portion, the sealing portion is protected. SUMMARY OF THE INVENTION In order to improve functions such as corrosion resistance, there are cases where separators having a corrosion-resistant coating on their surfaces are manufactured by treating a surface of a base material for the separators. At this time, the separators are sometimes formed by pressing the base material with its surface covered with a coating. In this case, part of the coating may be ruptured by the pressing, and the base material may be partially exposed. If the coating covering the sealing portion ruptures, electrolytic corrosion will progress from the portions where the coating has ruptured. As a result, pinholes may be formed in the sealing portion, which results in degradation in sealing performance. The present disclosure can be implemented in the following aspects. (1) An aspect of the present disclosure provides a fuel cell. The fuel cell includes: a plate member including a membrane electrode gas diffusion layer assembly and an insulating sheet that holds an outer peripheral portion of the membrane electrode gas diffusion layer assembly; and an anode separator and a cathode separator that sandwich the plate member. Each of the anode separator and the cathode separator includes a coating on its surface. Each of the anode separator and the cathode separator includes a body, a coolant manifold, an intra-cell sealing portion, and a sacrificial electrolytic corrosion portion. The coolant manifold is an opening in the body, and is configured to allow a coolant to flow therethrough. The intra-cell sealing portion provides a seal between the anode separator and the cathode separator within the fuel cell. The intra-cell sealing portion is provided by the body being bonded to the insulating sheet so as to surround the coolant manifold. The sacrificial electrolytic corrosion portion is disposed between the coolant manifold and the intra-cell sealing portion. The sacrificial electrolytic corrosion portion includes a plurality of exposed portions where a base material is exposed without being covered with the coating. The sacrificial electrolytic corrosion portion includes at least one of the exposed portions on a straight line connecting the coolant manifold and the intra-cell sealing portion. According to this aspect, even when the surface is covered with the coating, the sacrificial electrolytic corrosion portion has more exposed portions than the remaining portions. Therefore, the sacrificial electrolytic corrosion portion can be preferentially electrolytically corroded over the remaining portions. This can reduce formation of pinholes in the intra-cell sealing portion. As a result, degradation in sealing performance can be reduced.(2) In the above aspect, the sacrificial electrolytic corrosion portion may include the exposed portion on each of two or more concentric circles centered around the coolant manifold. This aspect more reliably allows the sacrificial electrolytic corrosion portion to be preferentially electrolytically corroded over the remaining portions. Accordingly, formation of pinholes in the intra-cell sealing portion can be more reliably reduced. As a result, degradation in sealing performance can be more reliably reduced.(3) In the above aspect, the sacrificial electrolytic corrosion portion may include the exposed portions at an interval of 10 µm or less. This aspect more reliably allows the sacrificial electrolytic corrosion portion to be preferentially electrolytically corroded over the remaining portions. Accordingly, formation of pinholes in the intra-cell sealing portion can be more reliably reduced. As a result, degradation in sealing performance can be more reliably reduced.(4) Another aspect of the present disclosure provides a method for manufacturing a fuel cell. The method includes a plate preparation ste