JPH05101837A - Seal structure of fuel cell - Google Patents

Abstract

PURPOSE:To eliminate gas leakage at the end of an electrode by forming each unitary cell of a fuel cell from a high polymer electrolyte and gas diffusion electrodes pinching it, and furnishing this unitary cell with a resilient sealing member having a high electric insulation embodied in such a form as enwrapping in a single piece the cell end faces and the oversurface and undersurface of each cell end, and with a separator having a sealing surface in contact with the sealing member. CONSTITUTION:A resilient sealing material 4 having electric insulation such as a sealant of silicon rubber type is applied in a single piece to the top and bottom faces (b) of each unitary cell and the end faces (a) of a gas diffusion electrode 1, a highpolymer electrolyte film 2, and again a gas diffusion electrode 1, followed by drying process. Thus gas leakage at the end of the electrode 1 is prevented, and also cross-leak due to mixing of the fuel with oxidating agent is eliminated by good adhesion with the film 2. Those portions (c) of sealing material 4 and separator 3 in contact with it which require sealing are equipped with a surface smoothness more than required to keep a sealing performance, and leak generation is eliminated even between the cell and separator 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell seal structure using a gas diffusion electrode.

[0002]

2. Description of the Related Art Fuel cells using conventional polymer electrolytes are flexible, and therefore, the elasticity (stretchability) of the sealing material.
Was not needed. Further, there is no structure that seals the cell edges when the cells are stacked.

[0003]

As described above, since the fuel cell and the stack using the polymer electrolyte have not been examined about the sealing property, the cell from the gas diffusion electrode end surface of the cell itself, In addition, there was a problem of gas leakage between the cell and the separator when stacking.

In view of the above-mentioned state of the art, the present invention is to provide a seal structure for a fuel cell which solves the above-mentioned problems.

[0005]

The present invention relates to a fuel cell comprising a polymer electrolyte and gas diffusion electrodes sandwiching the electrolyte, and a cell end face of the cell end and upper and lower faces of the cell end are integrally formed. A seal structure for a fuel cell, comprising a seal member having a wrapping shape and having a high electric insulation property, and a separator having an end portion with a seal surface against which the seal member abuts.

[0006]

The sealing material bonded to the end surface of the cell prevents leakage from the end portion of the gas diffusion electrode and sufficiently adheres to the polymer electrolyte to prevent cross leakage. In addition, the sealing material at the end of the cell surface exhibits a sealing property due to the deformation caused by the contact with the separator and prevents leakage from between the cell and the separator.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a schematic view for explaining a means for forming a fuel cell of the present invention as a sealing structure, FIG. 2 is a schematic cross-sectional view of a fuel cell in which a sealing material is joined, and FIG. A schematic view and FIG. 4 are schematic perspective views of a stack. In the figure, 1 is a gas diffusion electrode, 2 is a polymer electrolyte membrane, 3 is a separator, 4
Is a seal material, 5 is an end flange, 6 is a bolt, and 7 is a manifold.

As shown in FIG. 1, a silicon rubber-based sealant (such as a seam or a gap is filled in the cell end surface a composed of the gas diffusion electrode 1, the polymer electrolyte membrane 2 and the gas diffusion electrode 1 and the cell upper and lower surfaces b). Then, as shown in FIG. 2, a sealing material 4 having elasticity and electric insulation, such as a material which is water-tight or air-tight and whose material is rubber), is integrally applied and dried. By doing so, leakage from the end of the gas diffusion electrode 1 (arrow in FIG. 2) can be prevented, and sufficient adhesion to the polymer electrolyte membrane 2 can be achieved to cross-leak the fuel and the oxidant (see FIG. 2) can be prevented.

Further, a portion (c in FIG. 1) of the separator 3 which is in contact with the sealing material 4 on the surface of the fuel battery cell and which needs to have the sealing property is sealed by the contact with the sealing material 4 on the surface of the fuel battery cell. More than you can keep, for example JI
S Triangle symbol ▽▽ Finished above. By doing so, the sealing material 4 on the surface of the fuel cell exhibits a sealing property due to the deformation caused by the contact with the separator 3,
Leakage between the fuel cell and the separator 3 (see FIG.
Arrow) can be prevented.

When forming a stack, the intermediate layer has the separators 3 and the fuel cells alternately arranged, and the sealing materials 4 on the upper and lower surfaces of the fuel cells are sandwiched by the separators 3.
As shown in FIG. 4, the end flange 5 was tightened with a bolt 6 to form a stack.

[0011]

EFFECTS OF THE INVENTION It is not necessary to use many kinds of sealing materials, and it is not necessary to join the separator and the fuel battery cell with a sealant or an adhesive which is not dried at the time of stack assembly, so that the working efficiency is improved.

Further, since the sealing material has elasticity, even a fuel cell having flexibility (for example, one using a polymer film as an electrolyte) does not peel off and the sealing property is maintained.

Further, since the gas diffusion electrodes facing each other are completely insulated, the leakage current from the cell end is eliminated and the cell performance is improved. This is especially effective for small area cells.

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining a means for making a fuel cell of the present invention a sealing structure.

FIG. 2 is a schematic sectional view of a fuel cell unit in which a sealing material is joined.

FIG. 3 is a schematic cross-sectional view of a seal structure including a fuel cell and a separator.

FIG. 4 is a schematic perspective view of a stack.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inspector Sou Sada 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City Mitsubishi Heavy Industries Ltd. Hiroshima Research Institute (72) Inventor Yuuo Hirata 4-22 Kannon Shinmachi, Nishi-ku, Hiroshima (72) Inventor Satoshi Uchida 1-1, Atsunoura-machi, Nagasaki-shi Mitsubishi Heavy Industries Ltd. Nagasaki Shipyard Co., Ltd.

Claims (1)

[Claims] 1. A fuel cell comprising a polymer electrolyte and a gas diffusion electrode sandwiching the electrolyte, and an electric cell having elasticity such that a cell end surface of the cell end and upper and lower surfaces of the cell end are integrally wrapped. A seal structure for a fuel cell, comprising a seal member having a high insulating property, and a separator having a seal surface at an end portion with which the seal member abuts.