JPS628455A - Fuel cell - Google Patents

Abstract

PURPOSE:To prevent crack of electrode substrate and improve reliability by forming the bottom part of gas flow path in the side of end portion of the first and second electrode substrates thicker than the side of center thereof. CONSTITUTION:The bottom part 9a of gas flow path 7 in the side of end part of first, second electrode substrates 8 (thickness t) is formed thicker than the center part thereof. Thereby, thickness t of the bottom part 9a of gas flow path 7 at the edge part of electrode substrate 8 is larger than the thickness t of bottom part 9a of other gas flow path 7 and a shearing stress by the largest shearing stress to be applied to the bottom part 9a of gas flow path 7 at the end part of electrode substrate 8 is alleviated. Thereby, crack of electrode substrate 8 can be prevented and reliability can also be improved.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to fuel cells.

[Background of the invention]

FIG. 3 shows a conventional example of a fuel cell.

As shown in the figure, the fuel cell has a unit cell 1a having a pair of gas diffusion electrodes and an electrolyte disposed between them, and a battery body in which the unit cells 1a are stacked with a separator 1b in between. 2. A rod that tightens from the stacking direction. The battery includes a manifold 3, etc., which is provided on the side surface of the battery body and supplies and discharges oxidant gas and fuel gas to and from the battery body. In the figure, 4 is a fixed plate, 5 is a dummy electrode, and 6 is a current extraction terminal.

As shown in FIG. 4, a pair of gas diffusion electrodes is provided with an oxidizing gas flow path 7al on one side.

The first electrode substrate 8a has a catalyst (not shown) fully coated on the other surface, and the second electrode substrate 8a has a fuel gas passage 7b on one surface and has a catalyst (not shown) coated on the other surface. electrode substrate 8b
It has This first degree second electrode substrate 8a, 8b
have their catalyst-coated surfaces facing each other with an electrolyte interposed therebetween, and the gas flow paths 7a, ? b are arranged so that they are orthogonal. In addition, the first
．． Since the second electrode substrates 8a and 8b have exactly the same shape and configuration, the first electrode substrates 8a and 8b will be described below as follows. The second electrode substrates 3a and 3b are referred to as an electrode substrate 8, the oxidizing gas flow path 7a, and the fuel gas flow path 7b are referred to as a gas flow path 7. Furthermore, in the figure, 9 is the bottom of the gas flow path 7.

The unit cells 1a, which are stacked with a plurality of fuel cells configured in this way, are tightened by the rods 2 from the stacking direction as described above, but the unit cells 1a, the separators 1b, etc. have manufacturing tolerances in the thickness direction. Therefore, when a plurality of solder plates are stacked, the upper surface thereof will not be horizontal, and unevenness will occur on the central side of the solder substrate 8 with respect to its peripheral area. Therefore, in this state, the rod 2 is tightened via the fixing plate 4, so that the electrode substrate 8 has gas flow from the center side to the gas passage 7 at the end side, as shown in FIG. A large shearing force P is generated on the path 7, and cracks may occur on the end side. When cracks occur in this way, oxidizing gas and fuel gas mix through the cracks, and not only can regular power generation not be expected.
This causes combustion or explosion, causing a problem that causes the fuel cell to lose its function. Regarding this, there is Japanese Unexamined Patent Publication No. 57-208077.

[Object of the invention].

The present invention has been made in view of the above points, and it is an object of the present invention to provide a fuel cell that can prevent V& cracking of the electrode substrate and improve reliability.

[Summary of the invention]

That is, the present invention provides a pair of gas diffusion electrodes, a unit battery disposed between them and having a nine-ton solute, a rod for tightening the battery body in which the unit batteries are stacked in the stacking direction, and a rod attached to the side surface of the battery body. a manifold for supplying and discharging gas to and from the battery body;
dt iM has a first electrode substrate that has an oxidizing gas flow path on one side and a catalyst coated on the other side, and a first electrode substrate that has a fuel gas flow path on one side and has a catalyst coated on the other side. a second electrode substrate; The second electrode substrate is used in a fuel cell in which the catalyst-coated surfaces of the substrates are arranged opposite to each other with the electrolyte interposed therebetween. The second electrode substrate is characterized in that the thickness of the bottom of the gas flow path on the end side is larger than that on the center side. The bottom of the gas flow path on the end side of the second electrode substrate is formed to be thicker than the thickness on the center side.

[Embodiments of the invention]

The present invention will be explained below based on the illustrated embodiments. FIG. 1 shows an embodiment of the invention. Note that parts that are the same as those in the conventional system are given the same reference numerals, and therefore their explanations will be omitted. In this embodiment, the first. The thickness t of the bottom 9a of the gas flow path 7 on the end side of the second electrode substrate 8 was formed to be larger than that on the center side. By doing this, the thickness t of the bottom 9a of the gas flow path 7 on the end side of the stain electrode substrate 8 is changed from the thickness t on the center side.
It is possible to obtain a fuel cell in which the electrode substrate 8 is formed in a larger size, thereby preventing the electrode substrate 8 from cracking and improving reliability.

That is, the thickness t of the bottom 9a of the gas passage 7 on the end side of the electrode substrate 8 is made larger than the thickness t on the center side, but the thickness t of the bottom 9a of the gas passage 7 on the shoulder-most part of the electrode substrate 8 is Only the thickness t was formed larger than the thickness t of the bottom portion 9a of the other gas flow path 7. By doing this, the thickness t of the bottom 9a of the gas flow path 7 at the end of the stain electrode substrate 8 is made larger than the thickness t of the bottom 9a of the other gas flow path 7. As a result, the shear stress due to the largest shear force applied to the bottom 9a of the gas flow path 7 at the end of the electrode substrate 8 is alleviated, thereby preventing cracks in the electrode substrate 8 and improving reliability.

Another embodiment of the invention is shown in FIG.

In this embodiment, the thickness tl of the bottom 9a of the gas flow path 7 of the electrode substrate 8 is formed so that it becomes smaller toward the center of the electrode substrate 8 and becomes larger toward the ends. By doing this, the thickness t of the bottom portion 9a of the gas flow path 7 of the electrode substrate 8 becomes smaller toward the center of the electrode substrate 8 and becomes larger toward the end portions of the electrode substrate 8. The shearing stress applied to the bottom 9a of the gas flow path 7 can be made uniform, and the same effects as in the case described above can be achieved.

〔Effect of the invention〕

As mentioned above, the present invention prevents cracks in the electrode substrate, improves reliability, and prevents cracks in the electrode substrate.
A fuel cell with improved reliability can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional side view of an electrode substrate of one embodiment of the fuel cell of the present invention, FIG. 2 is a longitudinal sectional side view of an electrode substrate of another embodiment of the fuel cell of the invention, and FIG. 3 is a conventional FIG. 4 is a perspective view of the electrode substrate of a conventional fuel cell, and FIG. 5 is a longitudinal side view of the electrode substrate showing the distribution of shear stress applied to the gas flow path of the conventional fuel cell. It is. 1a...Unit battery, 1b...Separator, 2...
Rod, 3... Manifold, 4... Fixed plate, 7...
- Gas flow path, 7a... Oxidizing gas flow path, 7b... Fuel gas flow path, 8... Electrode substrate, 8a... First electrode substrate, 8b... Second electrode substrate , 9a... bottom of gas flow path, P... shearing force.

Claims (1)

[Claims] 1. A unit battery having a pair of gas diffusion electrodes and an electrolyte disposed between them; a rod that tightens the battery body in which the unit batteries are stacked in the stacking direction; a rod provided on the side surface of the battery body; The main body is equipped with a manifold for supplying and discharging gas, and the pair of gas diffusion electrodes have an oxidant gas flow path on one surface, a first electrode substrate coated with a catalyst on the other surface, and a first electrode substrate coated with a catalyst on the other surface. A fuel gas flow path is provided, and a second electrode substrate is coated with a catalyst on the other surface, and the catalyst coated surfaces of the first and second electrode substrates are arranged facing each other with the electrolyte interposed therebetween. In fuel cells that
A fuel cell characterized in that the thickness of the bottom of the gas flow path on the end side of the first and second electrode substrates is larger than that on the center side.