JPH10106595A - End cell structure of fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an end cell structure of a fuel cell which can reduce thermal strain between an end plate or middle plate and a separator, ensure tight attachment between each electrode and separator and between each electrode and electrolyte plate, and can enhance the battery performance of the end cell. SOLUTION: An end cell structure is composed of cell holding thick plates 12 (end plate or intermediate holder) for use at the top stage, bottom stage or the middle stage of a plurality of cells constituting a fuel cell and a mask plate 14 attached to the end plates, and a seal member 16 (electrolyte plate) is pinched between the periphery of the mask plate and the thick plate. The seal member 16 holds a melting material (carbonates) melted at the operating temperature of the fuel cell, and the gap between the mask plate periphery and thick plate is sealed air-tightly by the surface tension of the molten material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molten carbonate fuel cell for directly converting chemical energy contained in fuel into electric energy, and more particularly, to a fuel cell end cell structure.

[0002]

2. Description of the Related Art In a molten carbonate fuel cell, a thin flat electrolyte plate (tile) 1 is sandwiched between a fuel electrode (anode) 2 and an air electrode (cathode) 3, as schematically shown in FIG. It comprises a cell 4 and a separator 5 sandwiching the cell 4 therebetween. Since the voltage of each cell 4 is low (around 0.8 V), a high voltage is obtained by stacking the cells 4 via the separator 5. The stacked fuel cells are called a fuel cell stack (or simply, a stack).

FIG. 4 is a schematic diagram of a fuel cell stack. As shown in this figure, electrodes (anode 2 and cathode 3) are respectively incorporated on the upper and lower surfaces of each separator 5, and a tile 1 is sandwiched therebetween to form a stack. Therefore, on the upper and lower surfaces of each separator 5, electrodes 2,
3 is provided with an internal manifold (not shown) for supplying an anode gas and a cathode gas to the reaction section, respectively.

Further, in the cells at the uppermost and lowermost stages (end cells) of the stack, two end plates 6 (only the upper one is shown) having an electrode accommodating portion on only one side are used. The two end plates 6 constitute a stack by sandwiching a large number of cells therebetween, and have a current terminal 7 so that a current generated by a fuel cell reaction is taken out. Also, the end plate 6
Is held at a predetermined surface pressure by the battery tightening device 8 so as to reduce the contact resistance between the cells constituting the stack. This battery fastening device 8
Is generally composed of a thick flat plate and a spring or a diaphragm for applying a uniform surface pressure to the flat plate. Similarly, when the number of stacked cells is large and an intermediate holder is used, the above-mentioned end cells are formed on the upper and lower surfaces of the thick intermediate manifold. Hereinafter, the intermediate manifold will be described including the end plate.

[0005]

In the above-mentioned conventional molten carbonate fuel cell, the cell performance of the end cell in contact with the end plate 6 (and the intermediate manifold) tends to be worse than other cells. This is considered to be one of the causes of the decrease in cell adhesion due to the rigidity of the end plate 6.

That is, in FIG.
Has a welded structure in which a center plate 5a and two mask plates 5b are joined to each other. The end cell has a configuration in which the center plate 5a of the separator is replaced with an end plate 6, and the end plate 6 has a mask plate. 5b is welded. However, since the separator 5 has a thin structure as a whole, it can follow a thermal expansion and a change in cell thickness. However, since the end cell includes the thick end plate 6 as a constituent element, a rigid end plate and a flexible separator are used. , Heat distortion is likely to occur between them, so that the adhesion between the electrode / separator and the electrode / electrolyte plate is deteriorated, and the cell performance tends to be worse than other cells.

For this reason, in particular, as the power generation output increases and the area of the cell reaction section increases, the voltage of the end cell becomes lower than that of the other cells, and the performance of the entire fuel cell deteriorates. . Similarly, when the number of stacked cells is large and an intermediate holder is used, there is a problem that the performance of end cells located on one or both surfaces of the intermediate holder is deteriorated.

The present invention has been made to solve such a problem. That is, an object of the present invention is to reduce thermal strain between an end plate or an intermediate holder and a separator, improve adhesion between an electrode / separator and between an electrode / electrolyte plate, and improve battery performance of an end cell. It is an object of the present invention to provide a fuel cell end cell structure that can be used.

[0009]

According to the present invention, a thick plate for holding a cell, which is used in the uppermost, lowermost or intermediate stage of a plurality of cells constituting a fuel cell, and which is attached to the thicker plate A sealing member is sandwiched between an outer peripheral portion of the mask plate and the thick plate, and the sealing member holds a molten material melted at an operating temperature of the fuel cell. There is provided an end cell structure of a fuel cell, wherein an airtight seal is provided between an outer peripheral portion of a mask plate and a thick plate by a surface tension of a molten material.

According to the present invention, the outer peripheral portion of the mask plate and the thick plate (for example, the end plate) are not welded and joined, but a seal member is sandwiched therebetween, and the seal member is operated at the operating temperature of the fuel cell. The outer peripheral portion of the mask plate and the thick plate are hermetically sealed by the surface tension by holding the molten material melted in the step, so that there is a difference in thermal expansion between the rigid thick plate and the mask plate. Even with this, thermal distortion can be absorbed by relative movement while maintaining airtightness at the seal member.

That is, according to the present invention, the seal welding between the end plate and the mask plate is stopped, and the adhesion between the end plate and the cell is improved by soft sealing by wet sealing. The thermal strain between the end plate and the separator can be absorbed by the soft seal part, reducing the thermal strain between the end plate and the separator, improving the adhesion between the electrode / separator and the electrode / electrolyte plate, and improving the battery performance of the end cell. Can be.

According to a preferred embodiment of the present invention, the thick plate is an end plate or an intermediate holder,
The sealing member is an electrolyte plate, and the molten material is a carbonate. According to this configuration, since the electrolyte plate used between the separators is used as the sealing member, the characteristics of the end cell can be matched to the characteristics of the other cells. Preferably, the gas manifold portion of the mask plate is welded to the thick plate. With this configuration,
The mask plate and the thick plate (end plate or intermediate holder) can be securely joined at the gas manifold portion that does not directly affect the battery performance.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. In the drawings, common parts are denoted by the same reference numerals. FIG. 1 is a structural diagram of a fuel cell end cell according to the present invention. In this figure, an end cell 10 of the present invention is used in the uppermost, lowermost, or intermediate stages of a plurality of cells constituting a fuel cell, and has a thick plate 12 for holding cells (end cells).
And a mask plate 14 attached to the thick plate 12. The thick plate 12 is an end plate or an intermediate holder.

In the end cell 10 of the present invention, a seal member 16 is further sandwiched between the outer peripheral portion of the mask plate 14 and the thick plate 12. This sealing member 16
The molten material melted at the operating temperature of the fuel cell is held, and the outer peripheral portion of the mask plate 14 and the thick plate 12 are hermetically sealed by the surface tension of the molten material. Preferably, the sealing member 16 is an electrolyte plate,
The melt is a carbonate. Note that another molten material, for example, glass may be used as the sealing material.

The gas manifold portion (in this case, an internal manifold, not shown) of the mask plate 14 is preferably welded to the thick plate 12. With this configuration, the mask plate 14 and the thick plate 12 (end plate or intermediate holder) can be securely joined at the gas manifold portion that does not directly affect the battery performance.

FIG. 2 is a diagram schematically showing the thermal deformation of FIG. 1, and the state of the thermal deformation is indicated by a two-dot chain line. As shown in this figure, according to the configuration of the present invention described above, the outer peripheral portion of the mask plate 14 and the thick plate 12 (for example, an end plate) are not welded and joined, and the seal member 1 is provided therebetween.
6, the sealing member 16 holds the molten material melted at the operating temperature of the fuel cell and hermetically seals between the outer peripheral portion of the mask plate 14 and the thick plate 12 by the surface tension. Even if there is a difference in thermal expansion between the rigid thick plate 12 and the mask plate 14, the sealing member 16 is kept airtight at the sealing member 16 portion.
The thermal strain can be absorbed by the relative movement on the surface.

Further, the characteristics of the end cell can be adjusted to those of other cells by using a carbonate as a melting material and using an electrolyte plate used between the separators as a sealing member.

It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various changes can be made without departing from the gist of the present invention.

[0019]

As described above, the end cell structure of the fuel cell according to the present invention reduces the thermal strain between the end plate or the intermediate holder and the separator, and improves the adhesion between the electrode / separator and the electrode / electrolyte plate. And the cell performance of the end cell can be improved.

[Brief description of the drawings]

FIG. 1 is a structural diagram of a fuel cell end cell according to the present invention.

FIG. 2 is a diagram schematically showing thermal deformation of FIG.

FIG. 3 is a schematic view of a molten carbonate fuel cell.

FIG. 4 is a schematic diagram of a fuel cell stack.

[Explanation of symbols]

 Reference Signs List 1 electrolyte plate (tile) 2 fuel electrode (anode) 3 air electrode (cathode) 4 cell (cell) 5 separator 5a center plate 5b mask plate 6 end plate 7 current terminal 8 battery tightening device 10 end cell 12 thick plate (end) Plate or intermediate holder) 14 Mask plate 16 Seal member

Claims (3)

[Claims] 1. A fuel cell comprising: a thick plate that is used as an uppermost, lowermost, or intermediate stage of a plurality of cells constituting a fuel cell and holds a cell; and a mask plate attached to the thicker plate. A seal member is sandwiched between an outer peripheral portion of the mask plate and the thick plate, and the seal member is
An end cell structure for a fuel cell, wherein a molten material melted at an operating temperature of a fuel cell is held, and a gap between an outer peripheral portion of a mask plate and a thick plate is hermetically sealed by a surface tension of the molten material. 2. The thick plate is an end plate or an intermediate holder, the sealing member is an electrolyte plate,
2. The method according to claim 1, wherein the molten material is a carbonate.
3. The end cell structure of the fuel cell according to 1. 3. The end cell structure for a fuel cell according to claim 1, wherein the gas manifold portion of the mask plate is welded to the thick plate.