JPH10228918A - End cell structure of fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an end cell structure of the fuel cell being capable of improving the cell performance at the end cell by reducing thermal strain between the holder or the intermediate holder and the separator, and improving the adhesion performance between the electrode and the separator, and the electrode and the electrolyte panel. SOLUTION: On one side of a dummy separator 15, holding a cell applied upper most section, lower most section and intermediate section of multiple cells composing a fuel cell, and an end plate 16 adjoin the dummy separator 15 to make flow the process gas are equipped. The dummy separator 15 is the same as the separator 5 holding the cells on both side and the end plate 16 is the thick plate 16a with the master plate 16b. Moreover in the electrode part the conductive thin plates are layered corresponding thickness of the electrode and the thickness of the electrolyte plate and in the wet sealing part the sealing part 18 is inserted and fastened. The sealing part holds the melted material melting at the running temperature of the fuel cell, and maintains airtight between the dummy separator 15 and the end plate 16 by means of the surface tension of the melted 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 uppermost cell and the lowermost cell (end cell) of the stack, two holders 6 (only the upper one is shown: also referred to as an end plate) provided with an electrode accommodating portion on only one side are used. Can be The two holders 6 (or end plates) sandwich a large number of cells therebetween to form a stack, have a current terminal 7, and take out the current generated by the fuel cell reaction to the outside. . In addition, the entire stack including the holder 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. The battery tightening device 8 is generally composed of a thick flat plate, a spring for applying a uniform surface pressure to the flat plate, a pneumatic bellows, a pneumatic cylinder and the like. Similarly, the number of stacked cells is large,
When the intermediate holder is used, the above-mentioned end cells are formed on the upper and lower surfaces of the thick intermediate holder. Hereinafter, the intermediate holder will be described including the intermediate holder.

[0005]

In the above-described conventional molten carbonate fuel cell, the cell performance of the end cell in contact with the holder 6 (and the intermediate holder) tends to be worse than other cells. This is because while the rigidity of the holder 6 is high, the separator is thermally flexible due to the thin plate structure, and the cell components (electrodes 2 and 3, the electrolyte plate 1, the separator 5 It is considered that one of the causes is that the adhesiveness of ()) is reduced.

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 a holder 6, and the mask plate 5b is attached to the holder 6. It has a joined welded structure. However, separator 5
Has a thin structure as a whole, so that it can follow thermal expansion and changes in cell thickness. However, since the end cell includes the thick holder 6 as a constituent element, thermal strain is generated between the rigid holder and the flexible separator. Is likely to occur, so the electrode /
Adhesion between separators and electrodes / electrolyte plates deteriorated, and cell performance tended 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 a holder 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 to provide an end cell structure of a fuel cell.

[0009]

According to the present invention, there is provided a dummy separator which is used at the uppermost, lowermost or intermediate stage of a plurality of cells constituting a fuel cell and holds cells on one side, and which is in contact with the dummy separator. An end plate through which a process gas flows, between which the dummy separator is the same as the separator holding the cells on both sides, and the end plate has a thick plate attached with a mask plate, and a dummy separator. Between the end plates,
A conductive thin plate corresponding to the thickness of the electrode and the electrolyte plate is laminated on the electrode portion, a seal member is sandwiched on the wet seal portion, and the seal member holds a molten material melted at the operating temperature of the fuel cell. And an airtight seal between the dummy separator and the end plate by the surface tension of the molten material.

According to the present invention, since the dummy separator holding cells on one side has the same shape and material as the separator holding cells on both sides, it has the same thermal flexibility. The thermal strain between them is equivalent to that of other cells, and it is possible to prevent the adhesion of the cell constituting members (electrodes 2 and 3, electrolyte plate 1 and separator 5) from decreasing.

Further, between the dummy separator and the end plate, a current generated by the stack can flow to the end plate (ie, holder) by a conductive thin plate laminated on the electrode portion. Further, a seal member is sandwiched between the wet seal portions, and the gap between the dummy separator and the end plate is hermetically sealed by the surface tension of the molten material held by the seal member. This prevents the process gas from flowing through the dummy separator and the end plate without reacting, so that the temperature can be maintained equal to that in the other stacks.

According to a preferred embodiment of the present invention, the thick plate is a holder 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. Further, it is preferable that the outer peripheral portion of the mask plate and the gas manifold portion are welded to the thick plate. With this configuration, the mask plate and the thick plate (holder or intermediate holder) can be securely joined at the outer peripheral portion and the gas manifold portion.

[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 configuration diagram of a fuel cell having an end cell structure according to the present invention. In this figure, the fuel cell (stack) has an intermediate holder 13 between upper and lower holders 11 and 12, and sandwiches an upper and lower stack 14 between the intermediate holder 13 and the upper and lower holders 11 and 12, respectively. Gas is made to flow in / out of the intermediate nelda 13. Such a structure is the same as the conventional one.

In FIG. 1, according to the present invention, the end cell 10 of the present invention is used at the uppermost, lowermost, or intermediate stage of a plurality of cells constituting a fuel cell.

FIG. 2 is a structural view of a fuel cell end cell according to the present invention. As shown in this figure, the end cell 10 of the present invention is the uppermost cell of a plurality of cells constituting a fuel cell,
It has a dummy separator 15 that is used in the lowermost or intermediate stage and holds cells on one side, and an end plate 16 that is in contact with the dummy separator 15 and through which a process gas flows.

As shown in FIG. 4, the normal separator 5 constituting the stack 14 has a welded structure in which the outer peripheral portion of the separator 5 is joined to a center plate 5a and two mask plates 5b. A corrugated 5c formed by bending a thin plate is attached to both surfaces of the center plate 5a, and electrodes 2 and 3 are placed on the upper surface thereof to form a process gas flow path. Instead of using the corrugate 5c, the flow path may be formed by pressing the center plate 5a. Further, an opening plate (collector) (not shown) may be sandwiched between the electrodes 2 and 3 and the corrugate 5c to support the electrodes.

The dummy separator 15 has exactly the same shape and material as the separator 5 holding cells on both sides. The end plate 16 is a thick plate 1
A mask plate 16b similar to the separator 5 is attached to 6a. Further, as shown in FIG. 2, between the dummy separator 15 and the end plate 16, a conductive thin plate 17 corresponding to the thickness of the electrode and the electrolyte plate is laminated on the electrode portion, and a sealing member 18 is formed on the wet seal portion. Is pinched. The seal member 18 holds the molten material melted at the operating temperature of the fuel cell, and hermetically seals between the dummy separator 15 and the end plate 16 by the surface tension of the molten material.

The sealing member 18 is preferably an electrolyte plate, and the molten material is a carbonate. That is, the characteristics of the end cell can be matched to the characteristics of other cells by using a carbonate as a molten material and using an electrolyte plate used between the separators as a sealing member. Note that another molten material, for example, glass may be used as the sealing material.

The outer peripheral portion of the mask plate 16a and the gas manifold portion (in this case, an internal manifold, not shown) are preferably welded to the thick plate 16a.
With this configuration, the mask plate 16a and the thick plate 16b (holder or intermediate holder) can be securely joined at the outer peripheral portion and the gas manifold portion.

According to the configuration of the present invention described above, the dummy separator 15 for holding cells on one side has the same shape and material as the separator 5 for holding cells on both sides, so that it has the same thermal flexibility. Having this separator 1
The thermal strain between the cells 5 and 5 is equivalent to that of the other cells, and it is possible to prevent the adhesion of the cell constituting members (electrodes 2 and 3, electrolyte plate 1 and separator 5) from decreasing.

Further, between the dummy separator 15 and the end plate 16, a conductive thin plate 17 laminated on the electrode portion is provided.
As a result, the current generated by the stack is transferred to the end plate 16.
(Ie, a holder). Further, a seal member 18 is sandwiched between the wet seal portions, and the gap between the dummy separator 15 and the end plate 16 is hermetically sealed by the surface tension of the molten material held by the seal member 18. The process gas can be prevented from flowing between the dummy separator 15 and the end plate 16 without reacting, and the temperature can be kept equal to that in other stacks.

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

[0023]

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

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a fuel cell having an end cell structure according to the present invention.

FIG. 2 is a structural diagram of a fuel cell end cell according to the present invention.

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]

 DESCRIPTION OF SYMBOLS 1 Electrolyte plate (tile) 2 Fuel electrode (anode) 3 Air electrode (cathode) 4 Single cell (cell) 5 Separator 5a Center plate 5b Mask plate 6 Holder 7 Current terminal 8 Battery tightening device 10 End cell 11 Upper holder 12 Lower holder 13 Intermediate holder 14 Stack 15 Dummy separator 16 End plate 16a Thick plate 16b Mask plate 17 Thin plate 18 Seal member

Claims (2)

[Claims] 1. A dummy separator which is used at the uppermost, lowermost, or intermediate stage of a plurality of cells constituting a fuel cell and holds a cell on one side, and an end plate which is in contact with the dummy separator and through which a process gas flows therebetween. The dummy separator is the same as the separator that holds the cells on both sides, the end plate has a thick plate with a mask plate attached, and the electrode portion between the dummy separator and the end plate A conductive thin plate corresponding to the thickness of the electrode and the electrolyte plate is laminated, a seal member is sandwiched between the wet seal portions, and the seal member holds a molten material melted at the operating temperature of the fuel cell, and An end cell structure for a fuel cell, wherein a space between a dummy separator and an end plate is hermetically sealed by surface tension of a material. 2. The fuel cell end cell according to claim 1, wherein the thick plate is a holder or an intermediate holder, the sealing member is an electrolyte plate, and the molten material is a carbonate. Construction.