Fuel cell

Abstract

A fuel cell (10) includes a diffusion layer (13, 16) formed in a sheet having a small thickness. The fuel cell (10) is assembled with a tension imposed on the sheet in an in-plane direction of the sheet. The tension is imposed on the diffusion layer (13, 16) from a frame (29) disposed outside the fuel cell. The tension is of such a magnitude as to prevent a portion of the sheet (13, 16) positioned corresponding to a gas passage of a separator from being deformed when the fuel cell is assembled and has a tightening force thereby applied thereto. The tension is adjustable according to a fuel cell operating condition. These structures can prevent a separator rib from pushing into a membrane, maintaining the gas passability of the diffusion layer well.

Description

technical field [0001] The invention relates to a fuel cell, in particular to a diffusion electrode of a solid polymer electrolyte fuel cell. Background technique [0002] A solid polymer electrolyte fuel cell is constructed by stacking units composed of a membrane-electrode assembly (MEA: Membrane-Electrode Assembly) and separators in one or more layers to form a module. [0003] MEA includes an electrolyte membrane composed of an ion exchange membrane, a diffusion electrode (anode) composed of a catalyst layer and a diffusion layer arranged on one side of the electrolyte membrane, and a catalyst layer and a diffusion layer arranged on the other side of the electrolyte membrane. Composed of diffusion electrodes (cathode). A fuel gas flow path for supplying a fuel gas (hydrogen gas) to the anode and an oxidizing gas flow path for supplying an oxidizing gas (oxygen, usually air) to the cathode are formed on the separators sandwiching the MEA. In addition, in order to cool t...

AI Technical Summary

Problems solved by technology

[0009] However, the diffusion layer of laminated carbon fabric or carbon paper has low rigidity, and the electrolyte membrane and catalyst layer also have low rigidity, so the ribs (convex and convex parts) of the flow path of the separator will be affected by the fastening load of the laminated body. And sinking (embedding / eating) will cause bending on the diffusion layer and further on the electrolyte membrane, and the part of the diffusion layer and the electrolyte membrane that touches the corners of the ribs of the separator will deteriorate, resulting in durability of the fuel cell. reduce such problems

[0010] In order to improve the rigidity of the diffusion layer in order to eliminate the sinking into the membrane, it is considered that the diffusion layer is made of metal mesh or carbon paper, but the metal mesh has corrosion and the deterioration of the membrane caused by it, And the problem that the production cost is high, for carbon paper (composite materials such as carbon and phenolic resin (Fenol resin)), then there is a rib just below the rib when being squeezed by the rib of the flow path of the separator. The part will be compacted, thus causing problems such as poor air permeability

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