JPS5998472A - Molten salt fuel cell - Google Patents

Abstract

PURPOSE:To offer such a molten salt fuel cell as being simple in structure, long in service life and low-unit cost of production, by remodeling its solid structure comprising an electrolyte holding body and an interconnector plate. CONSTITUTION:Ribs 15 and 16 of an electrolyte holding body 14 and an interconnector plate 10 form an emply space for an electrode and a gas chamber. An opening part of this space is used for feed and discharge ports of gas, and an air vent is installed in the side of a layer-built cell whereby fuel gas and oxidizer gas are able to flow orthogonally. On the other hand, the interconnector plate 10 comes into contact with an electrode at its surface's projections 12 and 13, then presses these projections to the electrolyte holding body 14 and performs its role as a current collector, while also performs its role as an electrolyte supporter body, a gas separator and an interconnector plate. Moreover, the rib 15 on the electrolyte holding body 14 also had a function as an electrolyte reservoir, thus contributing to improvements in the service life of a cell.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a molten salt fuel cell that generates electricity at a high operating temperature using hydrogen, carbon oxide, etc. as a fuel gas and air or the like as an oxidant gas. This invention relates to a molten carbonate fuel cell using as an electrolyte.

Structures of conventional examples and their problems In general, molten salt fuel cells have high operating temperatures, and in the case of molten carbonate fuel cells, the operating temperature is around 650°C. Furthermore, in molten salt fuel cells, in addition to high temperatures, the molten salt itself is highly corrosive, so materials that can withstand long-term use are limited, such as ceramic materials, heat-resistant and corrosion-resistant alloys, etc.

An important technical issue is how to effectively use these limited materials to create a high-performance molten salt fuel cell with a simple structure.

Conventionally, in a phosphoric acid fuel cell, which is a room-temperature fuel cell, a groove forming a gas chamber is provided in an interconnector plate or electrode made of carbon, and the groove for fuel gas and the groove for oxidant gas are perpendicular to each other. A method is adopted in which the cells are stacked like this, and a vent is installed on the side of the stack to supply gas to each cell in parallel.

Furthermore, an electrolyte-impregnated portion is provided on the interconnector plate as an electrolyte holder.

However, these methods are practical only when carbon can be used as a constituent material, and the following problems arise in molten salt fuel cells.

In other words, since carbon is oxidized and consumed at high temperatures, it is necessary to use a metal material as the material for the interconnector plate, but in this case, heat-resistant alloys and the like are difficult to process by pressure forming and sintering, unlike carbon. Therefore, cutting is required to create the grooves, but this is not realistic in terms of cost, and requires a certain thickness of the metal plate used as the interconnector plate from the viewpoint of processing accuracy, resulting in weight and material costs. This has no choice but to be extremely disadvantageous in terms of

In the method of providing grooves in the electrode itself, in the case of molten carbonate fuel cells, porous nickel sintered bodies, nickel oxide sintered bodies, etc. are used as electrode materials, so mechanical strength,
There are many difficulties in terms of cost and gas sealing.

Furthermore, the method of installing the electrolyte holding portion on the interconnector plate also requires the interconnector plate to have a certain degree of thickness, which is disadvantageous for the same reason as mentioned above.

As described above, in addition to providing grooves in the interconnector plate or the electrodes, a structure as shown in FIG. 1 has been considered for molten salt fuel cells.

In FIG. 1, 1 is an electrolyte holder, and 2 is a fuel electrode.

3.3' is a current collector/electrode supporting material, 4 is an interconnector plate, and 5 is an air electrode. This is interconnector board 4
band-shaped ridges 6, 6 at both ends of one surface, and rips 7, 7 perpendicular to the aforementioned lips at both ends of the other surface.
In addition to creating a space for the gas chamber and electrodes, a gas seal is formed by the lips and the electrolyte holder, and a vent is provided on the side of the stack to allow the fuel gas and oxidant gas to cross at right angles. It has been made possible to supply it.

However, this method requires a corrugated plate for current collection as a component in addition to the interconnector plate, and it is also difficult to install an electrolyte reservoir, making it difficult to maintain stable battery performance over a long period of time. .

In order to solve these problems, it has been considered to form the electrolyte holder itself into a shape similar to that of the interconnector plate shown in the conventional example, that is, a shape having two sets of orthogonal rib-like protrusions. According to this structure, the lip-like protrusion functions as an electrolyte reservoir, so that battery performance is improved and the battery structure can be simplified. However, since the shape of the electrolyte holder has a three-dimensional structure on both sides of the surface, it is extremely difficult to mold and sinter it, resulting in a disadvantage that the yield rate during production is poor.

OBJECTS OF THE INVENTION It is an object of the present invention to solve the conventional problems as described above, and to provide a molten salt fuel cell that has a simple structure, a long life, and a low manufacturing cost.

Structure of the Invention The present invention alternates between an electrolyte holder having a concave cross-section and strip-shaped lips at both ends, and an interconnector plate having strip-shaped lips at both ends and a plurality of current collecting protrusions on both sides of the flat part. The electrodes are stacked so that the lips at both ends are perpendicular to each other, electrodes are placed in the space formed between the electrolyte holder and the interconnector plate, and the fuel gas and oxidizer are placed in the remaining space in the direction perpendicular to each other. It is a molten salt fuel cell that can supply gas.

Description of examples FIG. 2 is a side view of a molten salt fuel cell according to the present invention.

FIG. 2 is an exploded perspective view of the main parts.

In these figures, reference numeral 1o denotes an interconnector plate, which has a concave cross section with strip-like lips 11, 11 at both ends, and has a plurality of current collecting protrusions 12 on both sides of the flat part.
It has 13. Reference numeral 14 denotes an electrolyte holder, which has band-shaped lips 16 and 15 at both ends.

16 is a fuel electrode, and 17 is an air electrode.

Interconnector board 10 above. A battery is constructed by stacking a fuel electrode 16°, an electrolyte holder 14, and an air electrode 17 such that the lip 11 of the interconnector plate and the lip 15 of the electrolyte holder 14 are perpendicular to each other.

FIG. 2 is a view seen from the direction ■ in FIG. 3.

In this way, the electrolyte holder 14 and the lips 15, 11 of the interconnector plate 10 form spaces for the electrodes and gas chambers. The opening of this space serves as a gas supply and exhaust port, and by providing a vent on the side of the stacked battery, fuel gas and oxidant gas can flow orthogonally. In addition, the interconnector plate 10 has protrusions 12 and 13 on its surface that come into contact with the electrode and press it against the electrolyte holder, thus acting as a current collector, as well as serving as an electrode support, a gas separator, and an interconnector plate. is fulfilled. Another important point is that the lip 15 on the electrolyte holder 14 functions as an electrolyte reservoir and contributes to improving battery life.

In this example, the electrolyte holder was made by adding a methanol solution of polyvinyl butyral as a molding agent to lithium aluminate powder as a matrix material and press-molding it, and then drying it thoroughly and gradually increasing the temperature. The sample was heated and sintered by keeping it at a maximum temperature of 120°C for 2 hours.

In this case, the yield9 from molding to completion of sintering exceeded 90%, which was a high yield compared to only around 60% in the case of an electrolyte holder with lips on both sides manufactured using the same method. Showed the holder. The thus obtained electrolyte holder in a so-called unglazed state was impregnated with molten carbonate to obtain an electrolyte holder.

In addition, the interconnector plate is made by molding a heat-resistant and corrosion-resistant alloy plate with a thickness of 0.2 to 0.0 mm with boss-shaped protrusions on both sides.
2.13 was press-formed into a certain shape, and a 2 mm thick homogeneous alloy plate was welded to both ends as lips 15. A battery was assembled using a gas diffusion electrode made of a nickel alloy as a fuel electrode and a gas diffusion electrode made of nickel oxide containing lithium as an air electrode.

FIG. 5 compares the change over time in the terminal voltage of a single cell between the battery according to the present invention shown in the above embodiment and the conventional battery B shown in FIG.

Hydrogen gas was used as the fuel gas, and a mixed gas of air and carbon dioxide was used as the oxidant gas. The fuel electrode is a gas diffusion electrode made of a nickel alloy, the air electrode is a gas diffusion electrode made of nickel oxide containing lithium, and the electrolyte is a mixed salt of lithium carbonate and potassium carbonate. Operating temperature is 65
0℃, discharge 120 m/4/an? With a constant current discharge of
Do not replenish electrolytes.

As is clear from the figure, the battery AI'i according to the present invention and the conventional battery B have better characteristics.

This is because the lip on the electrolyte holder functions as an electrolyte reservoir. The battery according to the present invention has a life approximately 1.3 times longer than that of a conventional battery in which the electrolyte holder is a simple flat plate.

In manufacturing, the current collector, which was indispensable in conventional examples, has been replaced with current collecting protrusions formed by press molding on the interconnector board, reducing the number of battery component parts and required materials. is possible. By reducing the number of parts and required materials, it has become possible to reduce costs by about 20 to 30%. Also, the weight is reduced by about 10% compared to the conventional example.

In the above embodiments, the battery shape is rectangular, but the shape may be circular, polygonal, or any other shape. In short, there is an electrolyte holder that has a lip on the peripheral edge of one side, a lip on the peripheral edge of one side, and a plurality of protrusions on the flat part, and these protrusions function as current collectors and electrode supports. It is only necessary to have a structure in which the connector plates are closely attached to each other and form a gas chamber/electrode storage space with a suitable gas inlet/outlet.

Furthermore, although there is no lip at all near the center of the gas inlet/outlet, electrolyte holder, and interconnector plate in the example, lip-like protrusions are provided at necessary locations to improve strength against lamination pressure. Also good.

Effects of the Invention As described above, the molten salt fuel cell according to the present invention has a structure in which the electrolyte holder has a lip only on one side, and since one side is completely flat, it has a lip on both sides. Molding and sintering are easier than in the conventional case. Therefore, the yield during manufacturing is improved, and manufacturing costs can be reduced.

Furthermore, since the lip on the electrolyte holder functions as an electrolyte reservoir, the battery performance is greatly improved compared to conventional batteries using a simple flat plate-shaped electrolyte holder.

In addition, the interconnector plate has the function of a current collector and can be easily manufactured by pressing metal plates and some welding, which reduces battery weight and manufacturing costs compared to conventional examples. It is possible to lower the

[Brief explanation of drawings]

Fig. 1 is an exploded perspective view of the main parts of a conventional molten salt fuel cell, Fig. 2 is a side view showing the configuration of a molten carbonate fuel cell according to an embodiment of the present invention, and Fig. 3 is an exploded perspective view of the main parts. , FIG. 4 is a cross-sectional view of the interconnector plate taken along the line ■--■ in FIG. 3, and FIG. 5 shows a comparison of battery performance. 10---Interconnector plate, 11... Rib. 12.13°...°°° protrusion, 14... Electrolyte holder, 15°゛° lip, 16-゛---- fuel electrode,
17°°°°°゛Air pole. Name of agent: Patent attorney Toshio Nakao and one other person ζN

Claims (1)

[Claims] An electrolyte holder with a concave cross section with band-shaped lips on both ends,
An interconnector plate with a concave cross section, which has band-shaped lips at both ends and a plurality of protrusions for current collection on both sides of the planar part, is connected to the interconnector plate so that the lips at each end are perpendicular to each other and are opposed to the top surface of the lips. A molten salt fuel cell configured so that the bottom surfaces of the other side are in close contact with each other, electrodes are placed in the resulting space, and fuel gas and oxidizing gas are supplied orthogonally to each other into the remaining space. .