JPS62229767A - Fuel cell - Google Patents

Abstract

PURPOSE: To make a system compact and light weight by forming a cooling plate by sticking the first plate made of graphite and the second plate made of glassy carbon. CONSTITUTION: Graphite particles are molded by using pitch as a binder, and the pitch is graphitized at 2000 deg.C, and resin is impregnated under vacuum to obtain an impermeable graphite plate. Cooling pipe embedding grooves 17 are formed in an impermeable graphite plate 16 measuring 600 X 700mm. A cooling pipe 18 is embedded in the grooves 17 with a carbon-epoxy resin conductive adhesive 19 and the adhesive is cured to fix the cooling pipe 18, and thereby, the first plate is formed. A glassy carbon plate 20 measuring 600 X 700mm is bonded on the first plate as the second plate with a siver-epoxy resin adhesive 21 to form a cooling plate. Thereby, the thickness of the cooling plate is decreased and a system is made compact and light weight.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a fuel cell, and more particularly to a fuel cell having an improved configuration of a cooling plate having current collection and cooling functions.

[Technical Background of the Invention] Conventionally, fuel electricity has been used as a device that directly converts chemical energy contained in fuel into electrical energy.

2. Description of the Related Art Cells (hereinafter simply referred to as batteries) are known.

This battery usually has a pair of porous electrodes sandwiching an electrolyte layer, and the back of one electrode is contacted with a fuel gas that supplies hydrogen gas, and the back of the other electrode is contacted with a fuel gas that supplies hydrogen gas. By bringing an oxidizing gas into contact and utilizing the electrochemical reaction that occurs, electrical energy can be extracted from between both electrodes with high energy conversion efficiency.

By the way, based on the above principle, especially phosphoric acid (H3PO
A unit cell constituting a battery using 4) as an electrolyte is formed as follows. That is, as shown in FIG. 3, a unit cell is formed of carbon porous material on both sides of an electrolyte layer (hereinafter referred to as matrix) 1 impregnated with an electrolyte, and catalyst layers 2 and 2a are formed on each side of the matrix 1. An additional pair of electrodes 3.38 is provided. Roughly, both electrodes 3, 3a
A plate 5 (hereinafter referred to as an interconnector) having a rib 4 serving as a groove and a convex portion is disposed on the back side of the matrix 1 . On the surface of the interconnector 5 located on the electrode side, two parallel grooves are formed by the groove ribs 4 so as to be perpendicular to each other. A groove 7 on one side of the interconnector 5 serves as a flow path for fuel gas, and a groove 8 formed in an orthogonal direction on the other side serves as a flow path for oxidizing gas. A plurality of unit cells are stacked via the interconnector 5 formed in this way, current collecting plates are arranged at the upper and lower ends thereof, and insulating and tightening members are brought into contact and tightened together to stack the cells. form the body.

Then, as shown in FIG. 4, reaction gas supply containers (hereinafter referred to as manifolds) are arranged on mutually opposing surfaces of this battery stack. One opposing manifold 9,9
a supplies and discharges fuel gas, and the other opposed manifold 10.10a supplies and discharges oxidant gas, allowing both gases to flow through respective grooves of the interconnector 5 described above.

In this way, an interconnector type battery is constructed.

On the other hand, there is also a ribbed electrode type battery. As shown in FIG. 5, this battery is constructed by dividing the aforementioned interconnector 5 into a separator 11 and a rib 4. That is,
Ribbed electrodes 12.12a having catalyst layers 2, 2a formed thereon are arranged on both sides of the matrix 1 to form a unit cell.

Grooves 7, 8 and ribs 4 are formed on the opposite side of the ribbed electrode 12.12a that contacts the matrix 1, and the grooves 7, 8 and ribs 4 of both electrodes are formed in directions perpendicular to each other. Similar to interconnector.

When stacking a plurality of unit cells, they are stacked with a plate, that is, a plate-shaped separator 11 interposed therebetween, to prevent mixing of both gases, and a battery stack is formed in the same manner as described above. Attach the manifold to configure a ribbed electrode type battery.

In the interconnector type and ribbed electrode type batteries configured as described above, performance decreases due to deterioration of the catalyst layer due to temperature rise due to heat generation in the unit cell portion during operation. Therefore, in order to prevent this, in the case of an interconnector type battery, an interconnector type cooling plate 14 with cooling pipes 13 embedded in the interconnector 5 is installed for every several unit cells as shown in FIG. Arrange. Further, in the case of a ribbed electrode type battery, a separator type cooling plate 15 in which a cooling pipe 13 is embedded in the separator 11 is provided for every several unit cells as shown in FIG. In this way, the heat generated inside the unit cell is taken out to the outside to prevent the battery temperature from rising excessively.

[Problems with the Background Art] By the way, cooling plates for interconnector type and separator type batteries as described above both have high thermal conductivity and electrical conductivity in the stacking direction of unit cells, and are resistant to phosphorescence. It is required to have acidity, heat resistance, and dimensional stability. For this reason, graphite resin plates obtained by mixing and molding thermosetting resin and graphite particles,
The impermeable graphite plate is impregnated with resin to make it impermeable to gas, and the cooling tube is machined and fixed by embedding it with a heat conductive adhesive, and the embedded adhesive is also prevented from deteriorating when exposed to the battery atmosphere. In order to alleviate heat transfer imbalance in the high heat resistance part of the adhesive part, which accounts for 15 to 20% of the cooling plate surface, the cooling plate is formed by bonding plates of the same material with a highly conductive adhesive. are doing.

However, in the graphite resin plate or impermeable graphite plate which is a mixed molding material of thermosetting resin and graphite particles as described above,
It is very difficult to reduce the thickness of the cooling plate to 3M or less in a large-sized cooling plate of 500×500#+m or more because damage may occur during work. As a result, since the thickness of the cooling plate increases, the height per certain number of layers within the battery body increases, resulting in a problem that the battery becomes larger. Furthermore, since the thickness of the cooling plate is large, its weight becomes large, resulting in an increase in the weight of the battery body.

[Object of the Invention] The present invention was made to solve the above-mentioned problems, and its purpose is to reduce the thickness of the cooling plate and thereby reduce the size and weight of the device. Our goal is to provide the most reliable fuel cell possible.

[Summary of the Invention] In order to achieve the above object, the present invention arranges a pair of electrodes with an electrolyte layer in between, and injects a fuel gas onto the back surface of one electrode and an oxidant gas onto the back surface of the other electrode. A plurality of the unit cells are connected through a plate having a function of forming a unit cell that outputs electrical energy by flowing the fuel gas, preventing mixing of the fuel gas and the oxidizing gas, and electrically connecting the unit cells. In a fuel cell in which stacked cooling plates each having a cooling pipe embedded therein are disposed for each of the predetermined unit cells, the cooling plate includes a first plate made of a graphite plate having a cooling pipe embedded therein; It is characterized in that it uses a plate formed by bonding a second plate made of a carbon plate with a conductive adhesive.

[Embodiments of the Invention] First, the characteristics of the present invention are that the above-mentioned cooling plate is a graphite resin plate obtained by mixing and molding a thermosetting resin and graphite particles, or a graphite resin plate obtained by mixing graphite and a binder, The impermeable graphite plate is made impervious to gas by impregnating the graphite plate with resin, which has been molded and treated at high temperatures. Grooves for cooling management are embedded in the impermeable graphite plate, and cooling pipes are buried in a material with high heat conductivity. On top of the first plate formed by the above structure, the thickness of the Grassy Capo, which has heat resistance and corrosion resistance and is hardly penetrated by electrolyte and has a small thickness, is made small.

The present invention will be described below based on a specific embodiment shown in the drawings.

FIG. 1 is a perspective view showing an example of the configuration of a cooling plate according to the present invention. In the figure, graphite particles are molded using pitch as a binder, graphitized at 2000°C, and then impregnated with resin under reduced pressure on a 600 x 700 impermeable graphite plate 16 for embedding cooling pipes. form 17. Next, connect the cooling pipe 18 with carbon epoxy conductive adhesive 1.
9 is used to embed it in the cooling pipe embedding groove 17 and harden and fix it to form the first plate. Roughly place 600 m x 700 am x 1 sa on top of this first plate.
A cooling plate is formed by bonding a glassy carbon plate 20 having a shape t as a second plate to a silver epoxy conductive adhesive 2). FIG. 2 shows a cross-sectional view of such a cooling plate.

Next, Table 1 shows the shape and dimensions of the cooling plate according to this embodiment, and also shows the conventional cooling plate.

[Table 1] As is clear from Table 1, according to this embodiment, the thickness of one cooling plate can be made thinner by about 2) I11 than the conventional one. This means that the large capacity 400
In the case of a battery with stacked cells, if one cooling plate is provided for every 5 cells, the cooling plate will be approximately 160% lower than the conventional one.
This means that the stack height can be reduced by 111I11.

On the other hand, Table 2 shows the results of an investigation into the weight reduction of the cooling plate, regarding the weight of the laminated plate according to this example and the weight of the conventional laminated plate, respectively.

[Table 2] As is clear from Table 2, according to this example, 600X7
It is possible to reduce the weight by approximately 1.64 kg per 00m-shaped cooling plate. This corresponds to the 400
This means that in the case of a cell stack battery, it is possible to reduce the weight by about 130 kg.

Incidentally, as a result of a power generation test conducted by incorporating the cooling plate according to this example into a battery, no difference in cooling performance was observed compared to a battery incorporating a conventional cooling plate.

(Thus, according to the battery incorporating the cooling plate of this example, the decrease in electrical conductivity is smaller than that of a conventional cooling plate, so that the ohmic loss at the mating interface of the cooling plate due to operation is reduced. There is no increase in cooling efficiency, and there is no decrease in cooling efficiency due to an increase in thermal resistance, resulting in a high and constant power generation efficiency.Also, since the thickness of the cooling plate can be reduced, a constant power generation efficiency in the battery body can be achieved. It is possible to reduce the size of the battery by lowering the height per layer.Furthermore, since the weight of the cooling plate can be reduced for the above-mentioned reason, it is possible to reduce the weight of the battery body as a result.

In the above embodiment, carbon epoxy adhesive and silver epoxy adhesive were used as conductive adhesives, but such adhesives may be adhesives other than those mentioned above as long as they have an adhesive function and a conductive function. For example, it may be made of an adhesive resin such as a phenolic resin.

Further, in the above embodiment, an impermeable graphite plate is used as the first plate, but the present invention is not limited to this, and a graphite resin plate as described above may also be used.

In addition, the present invention can be implemented with various modifications without changing the gist thereof.

[Effects of the Invention] As explained above, according to the present invention, the first plate made of a graphite plate with cooling pipes embedded therein and the second plate made of a glassy carbon plate are bonded with a conductive adhesive. Since the structure is made using a material bonded together, it is possible to provide an extremely reliable fuel cell in which the thickness of the cooling plate can be reduced and the device can be made smaller and more compact.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a cooling plate according to an embodiment of the present invention, FIG. 2 is a sectional view showing a cooling plate according to the same embodiment, FIG. 3 is an exploded perspective view showing a unit cell of a battery, and FIG. 4 is a perspective view showing a battery incorporating the same unit cell, FIG. 5 is an exploded perspective view showing the unit cell of the battery, FIG. 6 is an exploded perspective view showing the cooling plate and the unit cell, and FIG. 7 is the cooling plate and unit. It is an exploded perspective view showing a cell. 14... Interconnector type cooling plate, 15...
・Separator type cooling plate, 16... Impermeable graphite plate, 17... Cooling pipe embedding groove, 18... Cooling pipe, 19
...Carbon epoxy conductive adhesive, 20...Gratsy carbon plate, 2)...Silver epoxy conductive adhesive. Applicant's agent Patent attorney Takehiko Suzue No. 1r7I Figure 2 Figure 3a Figure 4 Figure 5

Claims (1)

[Claims] (1) A pair of electrodes are arranged with an electrolyte layer sandwiched between them, and
A unit cell that outputs electrical energy is formed by flowing a fuel gas on the back surface of one electrode and an oxidizing gas on the back surface of the other electrode to prevent mixing of the fuel gas and the oxidizing gas and to prevent the unit cell from flowing between the fuel gas and the oxidizing gas. In the fuel cell, a plurality of the unit cells are stacked via plates having a function of electrically connecting the cells, and a cooling plate in which cooling pipes are embedded is arranged for each of the predetermined number of unit cells, As a cooling plate, the first plate is made of a graphite plate with cooling pipes embedded in it.
2. A fuel cell characterized in that it uses a plate formed by bonding the plate and a second plate made of a glassy carbon plate with a conductive adhesive. ■■■ Conductive adhesive is either carbon or silver ■■■
(2) The fuel cell according to claim (1), characterized in that one kind or a mixture thereof is used as a filler. (3) The fuel cell according to claim (1) or (2), wherein the conductive adhesive is made of an adhesive resin such as a phenolic resin or an epoxy resin.