CN-122025689-A - Fuel cell unit and method for manufacturing fuel cell unit

Abstract

The invention provides a fuel cell unit and a manufacturing method of the fuel cell unit. The fuel cell unit includes an anode separator and a cathode separator each having a coating film on a surface thereof, the anode separator and the cathode separator each include a main body portion, a coolant manifold through which a coolant flows, an intra-unit seal portion that seals between the anode separator and the cathode separator in the fuel cell unit by adhering the main body portion to an insulating sheet so as to surround the coolant manifold, and a replacement electrolytic etching portion that is disposed between the coolant manifold and the intra-unit seal portion and has a plurality of exposed portions that are exposed to the substrate without being covered by the coating film, the replacement electrolytic etching portion having at least one exposed portion on a straight line connecting the coolant manifold and the intra-unit seal portion.

Inventors

• TAKEHIRO NAOKI

Assignees

• 丰田自动车株式会社

Dates

Publication Date

20260512

Application Date

20250904

Priority Date

20241112

Claims (5)

1. 1. A fuel cell unit, wherein, The fuel cell unit includes: A plate member having a membrane electrode gas diffusion layer assembly and an insulating sheet for holding an outer peripheral portion of the membrane electrode gas diffusion layer assembly, and An anode separator and a cathode separator which sandwich the plate member and have a coating film on the surface, The anode separator and the cathode separator are each provided with: A main body portion; a coolant manifold formed in the main body portion and serving as an opening for circulating a coolant; An intra-cell sealing portion that bonds the main body portion to the insulating sheet so as to surround the coolant manifold, thereby sealing between the anode separator and the cathode separator within the fuel cell unit, and A replacement electrolytic etching portion disposed between the coolant manifold and the single body inner seal portion, the replacement electrolytic etching portion having a plurality of exposed portions exposed from the base material without being covered with the coating film, The replacement electrolytic etching portion has at least one of the exposed portions on a straight line connecting the coolant manifold and the intra-cell sealing portion.
2. 2. The fuel cell unit according to claim 1, wherein, The replacement electrolytic etching portions have the exposed portions on two or more concentric circles centered on the coolant manifold, respectively.
3. 3. The fuel cell unit according to claim 1, wherein, The replacement electrolytic etching portion has the plurality of exposed portions at intervals of 10 μm or less.
4. 4. A method for manufacturing a fuel cell unit, wherein, The manufacturing method of the fuel cell unit comprises the following steps: A plate preparation step of preparing a plate member having (1 a) a membrane electrode gas diffusion layer assembly and (1 b) an insulating sheet that holds an outer peripheral portion of the membrane electrode gas diffusion layer assembly; a substrate preparation step of preparing a substrate for an anode separator and a cathode separator, the substrate having (2 a) a main body, (2 b) a coolant manifold formed in the main body so as to be open and through which a coolant flows, and (2 c) an embossed portion disposed in the vicinity of the coolant manifold and having a plurality of protrusions protruding from the main body; a surface treatment step of treating a surface of the base material to form a coating film on the surface of the base material; A molding step of molding the anode separator and the cathode separator into a predetermined shape by press working the base material on which the coating film is formed, and A cell internal seal forming step of forming a cell internal seal in the fuel cell by bonding the insulating sheet to the main body so as to surround the coolant manifold in a state where the plate member is sandwiched between the anode separator and the cathode separator, The molding step includes an exposure step of stretching the protrusion by an external force applied by the press working to break the coating film on the protrusion, thereby forming a replacement electrolytic etching portion having a plurality of exposed portions exposed from the base material without being covered with the coating film.
5. 5. The method for manufacturing a fuel cell unit according to claim 4, wherein, The protrusion protrudes from a facing surface of the main body portion facing the insulating sheet toward a surface opposite to the facing surface.

Description

Fuel cell unit and method for manufacturing fuel cell unit Technical Field The present disclosure relates to fuel cell units and methods of manufacturing fuel cell units. Background Conventionally, there has been known a fuel cell unit including an anode separator and a cathode separator which sandwich a membrane electrode gas diffusion layer assembly and an insulating sheet which holds an outer peripheral portion of the membrane electrode gas diffusion layer assembly (japanese patent application laid-open No. 2023-16686). In this fuel cell, each separator has a coolant manifold through which a coolant flows, and a seal portion that seals between the anode separator and the cathode separator by being bonded to an insulating sheet. Each diaphragm has a replacement electrolytic portion disposed between the coolant manifold and the seal portion without being bonded to the insulating sheet. The replacement electrolytic etching portion is preferentially electrolytic etched than the sealing portion, thereby protecting the sealing portion. Disclosure of Invention In order to improve the functions such as corrosion resistance, a separator having a coating film with corrosion resistance on the surface may be produced by treating the surface of a base material of the separator. In this case, the separator may be formed by press working a base material whose surface is covered with a coating film. In this case, a part of the coating film may be broken by press working, and the base material may be partially exposed. In the case where the coating film covering the sealing portion is broken, electrolytic corrosion progresses from the broken portion of the coating film, and thus pinholes are generated in the sealing portion, and the sealing performance may be lowered. The present disclosure may be implemented as follows. (1) According to one aspect of the present disclosure, a fuel cell unit is provided. The fuel cell unit includes a plate member having a membrane electrode gas diffusion layer joined body and an insulating sheet for holding an outer peripheral portion of the membrane electrode gas diffusion layer joined body, an anode separator and a cathode separator which sandwich the plate member, each of the anode separator and the cathode separator having a coating film on a surface thereof, the anode separator and the cathode separator each including a main body portion, a coolant manifold formed in the main body portion and serving as an opening for allowing a coolant to flow therethrough, and a unit internal seal portion for bonding the main body portion to the insulating sheet so as to surround the coolant manifold, thereby sealing between the anode separator and the cathode separator in the fuel cell unit, and a replacement electrolytic portion disposed between the coolant manifold and the unit internal seal portion, the replacement electrolytic portion having a plurality of exposed portions exposed by the coating film, the substrate being exposed on at least one straight line connecting the coolant manifold and the unit internal seal portion. According to this aspect, even when the surface is covered with the coating film, the replacement electrolytic etching portion can be preferentially electrolytic etched over the other portion by having more exposed portions than the other portion. This can suppress occurrence of pinholes in the single-body inner seal portion. Therefore, the decrease in sealability can be suppressed. (2) In the above aspect, the replacement electrolytic etching portion may have the exposed portions on two or more concentric circles centered on the coolant manifold. According to this aspect, the replacement electrolytic etching portion can be preferentially etched over other portions more reliably. This can more reliably prevent pinholes from being formed in the seal portion in the single body. Therefore, the decrease in sealability can be more reliably suppressed. (3) In the above aspect, the replacement electrolytic etching portion may have the plurality of exposed portions at intervals of 10 μm or less. According to this aspect, the replacement electrolytic etching portion can be preferentially etched over other portions more reliably. This can more reliably prevent pinholes from being formed in the seal portion in the single body. Therefore, the decrease in sealability can be more reliably suppressed. (4) According to another aspect of the present disclosure, a method of manufacturing a fuel cell unit is provided. A method for producing a fuel cell includes a plate preparation step of preparing a plate member having (1 a) a membrane electrode gas diffusion layer joined body and (1 b) an insulating sheet for holding an outer peripheral portion of the membrane electrode gas diffusion layer joined body, a substrate preparation step of preparing a substrate having (2 a) a main body, (2 b) a coolant manifold formed in the main body as an opening and through which a coolant flows, (2 c) an em