JPH0193061A - Molten carbonate fuel cell - Google Patents

Abstract

PURPOSE:To prevent increase in the internal resistance of a fuel cell by flexibly forming a reaction gas passage forming body interposed between a current collector and a separator so as to press an electrolyte retainer, a gas diffusion electrode, and a current collector in the stacking direction. CONSTITUTION:Corrugated passage plates 4, 4' are interposed between current collectors 3, 3' and separators 5, 5' to form gas supply passages corresponding to gas diffusion electrodes 2, 2' respectively. By giving some flexibility to the passage forming structure, even if the thicknesses of an electrolyte retainer 1, electrodes 2, 2', and current collectors 3, 3' are not uniform and fastening pressure is not distributed uniformly, the flexible passage-forming body expands or contracts in the stacking direction to keep the compression between the electrolyte retainer 1 and the separators 5, 5'. Increase in the internal resistance of a fuel cell is prevented, and steady cell performance is retained for a long time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to fuel cells, and more particularly to a fastening structure suitable for molten carbonate fuel cells.

[Conventional technology]

Conventionally, the corrugated flow path constituting the gas supply path of a fuel cell has been described in National Fuel Cell Seminar Abstracts, p. 153, 1000 (National
l Fuel Ce1l Sem1nar/ Abst
(1980) P P 153 +, ).

Corrugated channel plates are also used in molten carbonate fuel cells, but no special measures such as tightening them from the inside have been taken.

[Problem that the invention seeks to solve]

In the above-mentioned conventional technology, no special consideration was given to the internal tightening structure between the electrolyte holding plate and the separator of the molten carbonate fuel cell, so the deformation of the electrolyte holding plate and There is a problem in that due to thermal contraction of the gas diffusive electrode, the contact between the electrolyte holding plate, the gas diffusive electrode, the current collector plate, and the separator is impaired, resulting in a gradual increase in resistance and a decrease in battery performance.

An object of the present invention is to provide a molten carbonate fuel cell with a structure in which a reaction gas flow path forming body sandwiched between a current collector plate and a separator has flexibility to be pressed in the stacking direction.
The object of the present invention is to provide a molten carbonate fuel cell that prevents an increase in internal resistance of the cell and has stable performance over a long period of time.

[Means for Solving the Problem] The above problem consists of an electrolyte holding plate using molten carbonate as an electrolyte, a pair of gas diffusive electrodes facing each other with the electrolyte holding plate in between, and the respective gas diffusing electrodes. a pair of current collector plates provided on the opposite side of the surface of the electrolyte holding plate that is in contact with the electrolyte holding plate; and a channel that forms a reactive gas supply path on the opposite side of the surface of the current collector plate that is in contact with the gas diffusive electrode. A plurality of unit cells of a molten carbonate fuel cell are stacked, each of which includes a pair of separators each having a forming body, wherein the flow path forming body includes the electrolyte retaining plate, the pair of gas diffusive electrodes, This problem can be solved by configuring the pair of current collector plates to have flexibility in the direction in which they are laminated.

[Effect]

The flexible reaction gas flow path forming body sandwiched between the current collector plate and the separator is pressed in the direction in which the electrolyte holding plate, the pair of gas diffusive electrodes, and the pair of current collector plates are stacked. expand and contract to maintain effective contact with each other.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 6.

The present invention is not limited to these examples.

FIG. 1 is a diagram showing a first embodiment of the present invention, and shows a cross section of a molten carbonate fuel cell. This example uses an elastic corrugated channel plate 4゜4' as a channel forming body, and includes an electrolyte holding plate 1 and a pair of gas diffusive electrodes (
It shows a structure in which a predetermined number of unit cells of a molten carbonate fuel cell are stacked, each of which has a negative electrode, a positive electrode) 2°2', a pair of current collector plates 3, 3', and a separator 5°5'. . The corrugated channel plates 4, 4' are sandwiched between the current collecting plates 3, 3' and the separator 5°5', and form channels for supplying gases corresponding to the gas diffusive electrodes 2, 2', respectively. .

The length between both ends a''-'a' of the corrugated channel plates 4, 4' is:

Use rice grains that are slightly longer than the length between the grooves bb' of the separators 5 and 5'. When assembling, set the waveform channels A and 4' to 5 to 57.
The corrugated channel plates 4, 4 can be assembled by compressing them to the length between them.
′ has a higher gap of e ”” e ′ and
Since the resistance force in the ``e'' direction also increases, it is possible to reliably press from the inside in the direction of stacking when tightening.

FIG. 2 is a sectional view showing a second embodiment of the invention. In this embodiment, at least one end of the corrugated channel plate 4 is curved with a gap of f' to f', which is higher than the gap between e'' and e', such as f. Since it is compressed by tightening, it is displaced in the direction of g. As a result, e ``'' e '' expands, so it can be tightened with flexibility from inside the battery.In this explanation, one corrugated channel plate 4 is shown. However, the other corrugated channel plate 4' can also have the same structure.

FIG. 3 is a sectional view showing a third embodiment of the present invention. A leaf spring 6,6' for supporting the corrugated flow path plates 4, 4' is provided in at least one portion of the interval between the waveform flow path plates 4, 4' and the separators 5, 5'.

The current collector plate 3.3' is always assembled by assembling the leaf spring 6.6' with a resistance force that presses it in the stacking direction.

The gas diffusive electrode 2.2' is kept pressed against the electrolyte holding plate 1 from the inside in the stacking direction. Although FIG. 3 shows one waveform channel plate 4, the other waveform channel plate 4' is also the same.

FIG. 4 is a sectional view showing a fourth embodiment of the present invention, and is an example in which an L-shaped channel plate 8 is used as the channel forming body. The L-shaped channel plate 8 is L
It has a structure in which it has a notch in the shape of a letter and is pushed up toward the current collector plate 3 at the upper end of the notch.

Further, a flexible sponge metal or ceramic spring 7 is placed under the L-shaped groove, and the spring 7 is always pressed from the inside in the stacking direction at a constant pressure or higher. The L-shaped channel ribs are distributed alternately as shown in FIG. 5 to uniformly distribute pressure within the plane. Although the structure of one channel forming body has been described in this embodiment, the structure of the other channel forming body may be similar.

FIG. 6 is a sectional view showing a fifth embodiment of the present invention. A bridge structure is employed in which a support 9 is formed between the current collector plate 3 and the separator 5 using a flexible sponge metal or a conductive ceramic spring.

Since reaction gas channels are formed at intervals between the columns, a simple structure can be achieved without using a channel plate, and the production process can be simplified. Although the structure of one channel forming body has been described in this embodiment, the structure of the other channel forming body can be similarly applied.

As described above, according to this embodiment, the structure of the channel forming body is flexible enough to be pressed in the stacking direction, so that the electrolyte retaining plate 1, gas diffusive electrode 2,
．． 2', Even if the thickness of the current collector plates 3 and 3' is uneven, the pressure may not be distributed evenly when tightened from the outside.
The flexible channel-shaped body expands and contracts in the stacking direction and can press between the electrolyte holding plate 1 and the separators 5, 5'. Furthermore, since the channel forming body is flexible within the plane, pressure can be kept uniformly distributed within the plane. Also, the electrolyte holding plate 1, gas diffusive electrodes 2, 2'
Even if thermal deformation occurs during operation, the flexible flow path forming body follows and deforms, so that the pressing pressure can be maintained in a uniform state within the plane. This can prevent an increase in contact resistance inside the battery and reduce deterioration in battery performance.

〔Effect of the invention〕

According to the present invention, in a molten carbonate fuel cell, the structure of a reactive gas flow path forming body sandwiched between a current collector plate and a separator is an electrolyte holding plate, a pair of gas diffusive electrodes, and a pair of collectors. By having a flexible structure that presses the electric plates in the stacking direction, it is possible to prevent an increase in the internal resistance of the battery due to an increase in contact resistance between the electrolyte holding plate and the separator due to long-term operation. It has particularly excellent effects on the electrostatic foaming performance of molten carbonate fuel cells.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a first embodiment of the present invention in which the structure of the channel forming body is a corrugated channel plate, and FIG. 2 is a sectional view showing a first embodiment of the present invention in which the structure of the channel forming body is a corrugated channel plate, and FIG. A sectional view showing a second embodiment of the present invention, FIG. 3 is a sectional view showing a third embodiment of the present invention in which the structure of the channel forming body is a corrugated channel plate and a plate spring, and FIG. FIG. 5 is a cross-sectional view showing a fourth embodiment of the present invention in which the structure of the forming body is an L-shaped channel plate and a spring; FIG. 5 is a plan view showing the arrangement of the L-shaped channel ribs in FIG. 4; FIG. FIG. 5 is a cross-sectional view showing a fifth embodiment of the present invention in which the channel forming body has a bridge structure using spring-like struts. DESCRIPTION OF SYMBOLS 1... Electrolyte holding plate, 2.2'... Gas diffusive electrode, 3.3'... Current collector plate, 4, 4'... Corrugated channel plate,
5゜5'... Separator, 6,6'... Leaf spring, 7
... Spring, 8 ... L-shaped channel plate, 9 ... Support.

Claims (1)

[Scope of Claims] 1. An electrolyte holding plate using molten carbonate as an electrolyte, a pair of gas diffusive electrodes facing each other with the electrolyte holding plate in between, and the electrolyte holding plate of each of the gas diffusive electrodes. a pair of current collector plates provided on the opposite side of the surface in contact with the gas diffusing electrode; and a pair of current collector plates provided with a flow path forming member forming a reaction gas supply path on the opposite side of the surface of the current collector plate in contact with the gas diffusive electrode. In the stacked unit cell of a molten carbonate fuel cell comprising a separator, the flow path forming body includes the electrolyte retaining plate, the pair of the gas diffusive electrodes, and the pair of current collecting plates. A molten carbonate fuel cell characterized by having flexibility in the direction of stacking. 2. The molten carbonate fuel cell according to claim 1, wherein the structure of the channel forming body is a flexible corrugated channel plate. 3. Claim 1, characterized in that the structure of the channel forming body is comprised of a corrugated channel plate and a leaf spring acting in the stacking direction between the corrugated channel plate and the separator. The molten carbonate fuel cell described in . 4. The molten carbonate fuel cell according to claim 1, wherein the structure of the flow path forming body is comprised of a plurality of elastic struts.