JPS6246950B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to fuel cells, and in particular to manifold type fuel cells.

Manifold-type fuel cells have come to be used for large-scale fuel cells, and as shown in Figures 1 to 3, fuel gas (e.g., hydrogen) is ),
The structure is such that an oxidant gas (for example, air) is supplied and discharged.

FIG. 1 is an exploded perspective view of battery components, FIG. 2 is a cutaway perspective view of essential parts showing the stacked state and appearance, and FIG. 3 is a sectional view of essential parts.

In these figures, reference numeral 1 denotes an electrode (fuel electrode or oxidizer electrode), which is made of graphite fiber, for example, and has many ribs on one side to form a gas flow path 7, and has an electrode on the other flat surface. For example, the catalyst layer 8 is provided by coating graphite powder in which platinum is diffused. These electrodes 1 are attached such that their flat surfaces are in close contact with a matrix 2 holding an electrolyte such as phosphoric acid, and the gas flow paths provided on each electrode are orthogonal to each other. are arranged to form a unit cell. Arrows A and B in FIG. 1 indicate the flows of fuel gas and oxidant gas, respectively. The unit cells configured in this way are stacked with a fuel gas and oxidant gas separator 3 interposed therebetween, and a cooler 4 is inserted between the stacks of the plurality of unit cells. The cooler 4 includes a cooling pipe embedded in a groove of a support plate.

A manifold that forms a space for supplying and discharging gas on the four sides of the battery body 5, which is thus composed of a unit cell and a cooler and is stacked using the battery fasteners 10 and the battery fastening rods 11. 6
is attached using a fixing band 12.

In this fuel cell, the electrolyte is held in the electrolyte holding material 2a of the matrix 2, which is located in the space formed by the seal member 9 that grips the electrode 1 from all four sides, as shown in FIG. has been done. Therefore, the electrolytic solution does not leak out from the sealing member 9, but the surface of the electrolytic solution that is in contact with the electrode 1 has pores, although the catalyst layer 8 is formed on that surface. Therefore, the electrolytic solution passes through the catalyst layer 8 and the electrode 1, flows out to the outside together with the fuel gas or the oxidant gas, and is consumed. As a result, when the electrolyte is consumed in this way, ion conduction becomes impossible, and the fuel cell loses its function.

In addition, the phosphoric acid used as a material for the electrolytic solution easily absorbs moisture, and while the concentration of phosphoric acid reaches 96% by weight or more during operation, the equilibrium concentration remains low even in dry conditions at room temperature and relative humidity of 30%. Since the difference is approximately 23% by weight, the volume increases compared to the used state, and this becomes a hindrance in battery assembly work and the like.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fuel cell having an easy-to-handle electrolyte flow path that can supply the electrolyte necessary for power generation after assembly of the fuel cell and replenish the electrolyte consumed during operation. For supplying and discharging gas to the fuel electrode and the oxidizer electrode, the side surface of the stack is made by stacking a plurality of unit cells with a fuel electrode and an oxidizer electrode facing each other with a separator interposed therebetween, through a matrix that holds an electrolytic solution. In a fuel cell in which a manifold is disposed, a seal portion located on the outer periphery of a unit cell, an electrolyte flow path provided in a component of the manifold and communicating with the matrix, and an electrolyte flow path connected to the electrolyte flow path. It is characterized by having a replenishment tank.

Examples will be described below.

4 to 7 show the main parts of one embodiment, respectively. Fig. 4 is a sectional view of the main part of the battery main body, Fig. 5 is a plan view of the main part, and Fig. 6 is a diagram of the main part of the fuel cell. FIG. 7 is a sectional view of the main parts and a perspective view of the manifold.

The main components of the fuel cell of this embodiment include an electrolyte supply path to a matrix holding the electrolyte, an electrolyte flow path provided in a manifold, and an electrolyte replenishment tank.

In these figures, 1 is an electrode using a porous conductor with good gas permeability, one surface of which is provided with many ribs to form a flow path 7 for fuel gas or oxidizing gas, and the other surface is provided with a number of ribs. It has a catalyst layer 8, and 2 is a matrix in which an electrolyte is supported on a porous and hydrophilic electrolyte holding material 2a made of a material with good phosphoric acid resistance such as silicon carbide. is the same as before. Reference numeral 9 denotes a sealing member made of an irregularly shaped material with good phosphoric acid resistance, such as fluorocarbon rubber, and holes 13 are provided in the four corners of this sealing member 9, which open in two directions sandwiching the corners of the sealing member 9. Similar to the matrix 2, this is filled with a porous and hydrophilic electrolyte holding material 2b made of a material with good phosphoric acid resistance such as silicon carbide. Therefore, when an electrolytic solution 14 such as phosphoric acid is supplied from the side of the cell, the electrolytic solution 14 is sucked by the electrolytic solution holding material 2b and is supplied to the entire surface of the electrolytic solution holding material 2a.

6 is the manifold, made of stainless steel or
The manifold 6 is made of metal coated with a fluorine-based paint to improve phosphoric acid resistance, and the part of the manifold 6 that is fixed to the sealing member 9 of the battery body 5 has a seal as shown in FIG. , has an endless concave groove 15, and the inner surface of this groove 15 is surrounded by an insulating material 16 such as fluorocarbon rubber having excellent phosphoric acid resistance, and the end surface thereof protrudes beyond the end surface of the manifold 6. The opening end of the insulator 16 is fixed so as to surround the opening of the hole 13 provided in the seal member 9. The space formed by combining the sealing member 9 and the manifold 6 is made of a porous, hydrophilic material molded from a material with good phosphoric acid resistance, such as silicon carbide, in order to retain the electrolyte, similar to the matrix 2. The electrolyte retaining material 2c is filled with an electrolyte retaining material 2c having a high phosphoric acid retention capacity to form an electrolyte flow path. Supplied.

8, 9, and 10 show embodiments in which different electrolyte replenishment tanks are provided, and FIG. 8 shows an electrolyte flow path formed in the manifold 6. An electrolyte replenishment tank 18 is provided in the manifold 6 to supply electrolyte to the manifold 6. It is supplied to the battery body via the flow path. The initially required electrolytic solution is supplied at the time of battery assembly, and subsequent replenishment for consumption of the electrolytic solution is performed from the electrolytic solution replenishment tank 18 each time.

Figure 9 is a perspective view of another embodiment, in which the electrolyte replenishment tank is provided in a part other than the manifold in the battery storage tank, and the same parts as in Figure 2 are given the same symbols. It has been done. In this fuel cell, an electrolyte replenishment tank 19 is attached to the upper part of the cell, and the electrolyte 14 is supplied to the electrolyte flow path of each manifold 6. When using the electrolyte replenishment tank 19 having such a structure, pressure can be applied to the electrolyte replenishment tank 19 to supply replenishment electrolyte to the battery body 5.

FIG. 10 is a sectional view of still another embodiment in which the electrolyte replenishment tank is provided outside the battery housing tank, and the same parts as in FIG. 2 are given the same reference numerals. This fuel cell is essentially different from the embodiment shown in FIG.
In this case, the liquid level gauge 21 is provided with a liquid level gauge 21, and consists of a container provided with an inlet and an outlet for the electrolytic solution. It is also effective in that it is possible to easily apply pressure to the electrolytic solution so that the electrolyte internal pressure is less than the replenishment tank pressure.
22 in this figure indicates a battery main body storage tank.

In this way, the fuel cell described in the example has a structure in which the electrolyte can be replenished into the cell body from the outside, so it is possible to supply the electrolyte during battery assembly and replenish the amount consumed during operation. and
In particular, since a flow path for the electrolyte is formed when the battery body and the manifold are combined, handling is easy.

As described above, the present invention provides a fuel cell having an easy-to-handle electrolyte flow path that can supply the electrolyte necessary for power generation after assembly of the fuel cell and replenish the electrolyte consumed during operation. This makes it possible and has great industrial effects.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of the cell components of a conventional fuel cell, FIG. 2 is a cutaway perspective view of the main parts showing the stacked state and appearance, and FIG. 3 is a sectional view of the main parts. FIG. 4 is a cross-sectional view of a main part of a fuel cell according to an embodiment of the present invention, FIG. 5 is a plan view of a main part, FIG. 6 is a cross-sectional view of a main part of a fuel cell, and FIG. is a perspective view of the manifold, FIG. 8 is a cutaway perspective view of the main part of the manifold of another embodiment, FIG. 9 is a cutaway perspective view of the main part of the manifold of another embodiment, and FIG. , also a cross-sectional view of another embodiment. DESCRIPTION OF SYMBOLS 1... Electrode, 2... Matrix (holding electrolyte), 3... Separator, 5... Battery body, 6... Manifold, 9... Seal member, 13... Hole, 14... Replenishment electrolyte, 15... Groove, 16... Insulator, 18,1
9, 20... Electrolyte replenishment tank, 21... Liquid level gauge,
22...Battery main body storage tank, 2a, 2b, 2c...
Electrolyte holding material.

Claims (1)

[Scope of Claims] 1. A plurality of unit cells each having a fuel electrode and an oxidizer electrode facing each other via a matrix holding an electrolytic solution are laminated with the fuel electrode and oxidizer electrode on the side surface of a stacked body with a separator interposed therebetween. In a fuel cell provided with a manifold for supplying and discharging gas to and from the electrodes, a seal portion located on the outer periphery of the unit cell and an electrolyte flow path provided in a component of the manifold and communicating with the matrix; A fuel cell comprising an electrolyte replenishment tank continuous with the electrolyte flow path. 2. An electrolytic solution flow path provided in a component of the manifold is provided at a portion where the manifold is attached to the seal portion, the inner surface is surrounded by an insulator, and a phosphoric acid-resistant porous material is provided inside the electrolyte flow path. A concave groove filled with an electrolyte retaining material made of a substance, and a side surface of the seal portion having an open end of an electrolyte flow path communicating with the matrix and an open end of an electrolyte flow path communicating with the matrix. The fuel cell according to claim 1, wherein the fuel cell is constructed as follows. 3. The fuel cell according to claim 1 or 2, wherein the electrolytic solution replenishment tank has means for increasing the internal pressure of the tank above the internal pressure of the matrix and replenishing and filling the electrolytic solution. .