JP7140590B2 - electrochemical cell stack - Google Patents

Description

Embodiments of the present invention relate to electrochemical cell stacks and insulation plates thereof.

A cell stack that constitutes a solid oxide fuel cell (Solid Oxide Fuel Cell, hereinafter simply referred to as SOFC) and a solid oxide electrolysis cell (Solid Oxide Electrolysis Cell, hereinafter simply referred to as SOEC) It is a laminate obtained by laminating a plurality of electrochemical cells (hereinafter referred to as single cells) each composed of at least an air electrode, an electrolyte, and a fuel electrode. This stack is arranged in a compressed state between a pair of upper and lower load receiving plates in order to ensure the airtightness of the fuel gas supplied to each unit cell. As a compression method, for example, a method of connecting upper and lower load receiving plates using bolts is known.

As another compression method, a method is known in which a compression spring is provided between the upper load-receiving plate and the laminate, and the laminate is compressed by the restoring force of this spring. More specifically, a pressing plate is superimposed on the upper end surface of the cell stack, and a compression spring is provided between this pressing plate and the upper load receiving plate. As a result, a load is applied from the pressing plate to the laminate due to the restoring force of the compression spring.

JP 2011-065909 A

By the way, the solid oxide type single cell constituting the laminate undergoes an electrochemical reaction at a high temperature of about 600° C. to 1000° C. (this temperature is hereinafter referred to as the operating temperature). In order to improve the performance of the laminate, it is required that the airtightness of the fuel gas can be secured even at this temperature, that is, the laminate can be stably compressed. However, in the case of the method of connecting the upper and lower load receiving plates using bolts, the bolts are creep-deformed at an operating temperature of about 600° C. to 1000° C., and the compression of the laminate is weakened. Moreover, in the case of the method using a compression spring, the compression spring is deformed at a high temperature of about 600° C. to 1000° C., so that the compression of the laminated body becomes weak as in the case of the bolt. Therefore, there is a demand for a structure that prevents thermal deformation of the load application mechanism and can apply a load stably even when the ambient temperature around the laminate is about the reaction temperature of the single cell.

Therefore, the problem to be solved by the present invention is to provide an electrochemical cell stack that can stably apply a load by preventing thermal deformation of the load applying mechanism even if the temperature atmosphere around the laminate is about the reaction temperature of the single cell. It is to provide the heat insulating board.

In order to solve the above problems, an electrochemical cell stack of an embodiment includes a laminate in which a plurality of single cells are laminated, and a heat insulating plate provided on at least one of the upper end surface and the lower end surface in the stacking direction of the laminate. and a load applying mechanism that is directly or indirectly in contact with the insulating plate and is arranged to apply a compressive load to the laminate.

According to the electrochemical cell stack and its heat insulating plate of the present invention, even if the temperature atmosphere around the stack is about the reaction temperature of the single cell, thermal deformation of the load application mechanism can be prevented and the load can be applied stably.

1 is a schematic diagram of an electrochemical cell stack according to a first embodiment; FIG. FIG. 4 is a schematic diagram of an electrochemical cell stack according to a modification of the first embodiment; FIG. 5 is a schematic diagram of an electrochemical cell stack according to another modification of the first embodiment; FIG. 2 is a schematic diagram of an electrochemical cell stack according to a second embodiment; FIG. 4 is a schematic diagram of an electrochemical cell stack according to a third embodiment;

(First embodiment)
FIG. 1 is a schematic diagram of an electrochemical cell stack according to the first embodiment. An electrochemical cell stack 1 includes a laminate 2, a load receiving plate 3, a heat insulating plate 4, a heat insulating wall member 5, and a fixing member 6 and a bolt 7 as a load applying mechanism. In the following description, the stacking direction (the z-axis direction in the drawing) is the direction in which the single cells and separators that make up the stack 2 are stacked, and the stacking direction is used as a reference when expressing the direction or a specific surface. Notated as For example, the upper surface indicates the upper surface in the stacking direction, the side surface indicates the side surface in the stacking direction, and the lower side indicates the lower side in the stacking direction. That is, in the following description, the notation representing the orientation is based on the stacking direction, and does not necessarily match the orientation with respect to the direction of gravity. In the drawings, the positive direction of the z-axis is defined as the upper side in the stacking direction.

The laminate 2 has a plurality of square-plate-like or disk-like unit cells in which a fuel electrode, an electrolyte, and an air electrode are sequentially laminated. This single cell is a solid oxide single cell used for SOFC and SOEC. A specific structure of a single cell is obtained by reducing a mixed sintered body of ceria (GDC) and nickel oxide (NiO) on one surface of a solid electrolyte made of, for example, yttria-stabilized zirconia (YSZ). A fuel electrode made of Ni-GDC or the like is formed, and an air electrode made of perovskite type oxide or the like is formed on the other surface of the electrolyte. The sides of the unit cells are surrounded by a separator, which is a conductive rectangular member, and a sealing material is arranged on the upper surface of the separator for separating gas atmospheres between adjacent unit cells. The laminated body 2 is formed by laminating a plurality of units each including a unit cell, a separator, and a sealing material. Each unit of separator and sealing material is provided with a plurality of passage holes penetrating in the stacking direction. This channel hole is formed by a supply channel for supplying fuel gas (hydrogen or steam) to the fuel electrode of the single cell and air to the air electrode when used as an SOFC, and a chemical reaction in the single cell. Each comprises an exhaust channel for exhausting the product gas. A pair of upper and lower end plates 2a and 2b are provided at the upper and lower ends of the laminate 2 so as to sandwich a plurality of unit cells, separators, and sealing materials.

The load receiving plate 3 is arranged above the upper end plate 2a. The load receiving plate 3 is a plate-like member formed in a circular or square shape, and is made of a highly rigid material such as stainless steel. This is for uniformly applying a load to the end plate on the upper end side of the laminate 2 via the fixing member 6 and the bolt 7, which are the load applying mechanism. In this embodiment, the load receiving plate 3 may be omitted, and the fixing member 6 may be provided on the heat insulating plate 4, which will be described later.

The heat insulating plate 4 constitutes a heat insulating member provided between the upper end plate 2 a of the laminate 2 and the load receiving plate 3 . That is, the heat insulating plate 4 contacts both the upper surface of the upper end plate 2 a and the lower surface of the load receiving plate 3 . Also, the heat insulating plate 4 is made of a material having a low thermal conductivity such as alumina. The material of the heat insulating plate 4 is not limited to this, and may be made of, for example, mullite, zirconia, or the like. The upper and lower surfaces of the heat insulating plate 4 have an area that is large enough to transmit the load received from the load receiving plate 3 to the laminate 2, for example, the cross-sectional area of the separator and the sealing material constituting the laminate 2 in a cross section perpendicular to the lamination direction. is more preferably at least half or more.

The heat insulating wall member 5 constitutes a rectangular heat insulating member surrounding the outside of the laminate 2 from the side surface of the heat insulating plate 4 . In this embodiment, the heat-insulating wall member 5 is made of heat-resistant reinforcing fiber such as glass wool. The material of the heat insulating wall member 5 is not limited to glass wool, and may be made of, for example, ceramic fiber or rock wool. More specifically, the load receiving plate 3 and the heat insulating plate 4 are configured to be enclosed in a hole provided in the heat insulating wall member 5 . This hole has an airtight structure so that heat is not emitted from the periphery of the laminate 2 . Here, the airtight structure means that the holes are designed so that the gaps between the load receiving plate 3 and the heat insulating plate 4 and the heat insulating wall member 5 are airtight. Another member having a small thermal conductivity may be provided between the heat insulating plate 4 to make it airtight.

The fixing member 6 is a plate-shaped member provided on the upper surface of the heat insulating wall member 5 . The fixing member 6 has, on the upper side of the load receiving plate 3, a bolt hole 6a, which is a screw hole for screwing and fixing a bolt 7, which will be described later. The fixing member 6 is tightened and fixed to the heat insulating wall member 5 using screws (not shown). As another configuration of the fixing member 6, for example, the lower surface of the heat insulating wall member 5 and the upper surface of the heat insulating wall member 5 may be adhered and fixed.

The bolt 7 is screwed into the bolt hole 6a of the fixing member 6 and fixed. A tip surface 7 a (thread tip) of the bolt 7 contacts the upper surface of the load receiving plate 3 . The bolt 7 is deeply screwed into the bolt hole 6a of the fixing member 6, and the load applied to the load receiving plate 3 from the tip surface 7a increases as the length of the portion protruding downward from the bolt hole 6a increases. That is, by adjusting the length of the bolt 7 protruding downward from the bolt hole 6a, the load applied to the load receiving plate 3 from the tip surface 7a is adjusted.

Next, the operation of this embodiment will be described. Fuel gas and oxygen are supplied from the outside to the fuel electrode and the air electrode that constitute the single cell of each unit, respectively, through flow passage holes on the supply side provided in the separator and sealing material of the laminate 2 . When used as an SOFC, hydrogen is supplied as fuel gas, and the single cell causes an electrochemical reaction (power generation reaction) to generate electric energy, reaction heat, and steam. The water vapor generated here is discharged to the outside through the discharge-side channel holes provided in the separator and the sealing material.

On the other hand, when used as an SOEC, a DC current and water vapor, which is a fuel gas, are supplied from the outside to cause an electrolysis reaction in the single cell to decompose the water vapor into hydrogen and oxygen. Hydrogen and oxygen generated by the electrolysis reaction are respectively discharged to the outside through passage holes on the discharge side provided in the separator and sealing material.

In either case, the temperature of the reaction in the single cell is as high as about 600° C. to 1000° C., so the portion surrounded by the heat insulating plate 4 and the heat insulating wall member 5 (around the laminate 2) is A higher temperature atmosphere is created. However, since heat radiation to the fixed member 6 and bolt 7 side is suppressed by the heat insulating plate 4 and the heat insulating wall member 5, the amount of heat transferred to the fixed member 6 and the bolt 7 is reduced.

According to the first embodiment described above, the laminate 2 is accommodated inside the heat insulating plate 4 and the heat insulating wall member 5, and the fixing member 6 and the bolt 7, which are the load applying mechanism, are provided on the upper surface of the heat insulating wall member 5. As a result, the amount of heat transferred from the surroundings of the laminate 2, which is in a high-temperature atmosphere, to the fixing members 6 and bolts 7, which are load applying mechanisms, is reduced. A load can be applied stably by preventing thermal deformation of the additional mechanism. In addition, since the fixing member 6 and the bolt 7 block heat from the laminate 2 through the heat insulating plate 4 and the heat insulating wall member 5, the material constituting the fixing member 6 and the bolt 7 does not necessarily have to be at the reaction temperature of the single cell. It is not necessary to have heat resistance to the extent that it can withstand Therefore, an electrochemical cell stack can be constructed at a lower cost than conventionally.

In this embodiment, the case where the load receiving plate 3, the heat insulating plate 4, the fixing member 6, and the bolt 7 are arranged only on the upper side in the stacking direction will be described as an example, but the installation positions are not limited to this. For example, they may be provided on the lower side in the stacking direction, or may be provided on the upper side and the lower side in the stacking direction.

In addition, although FIG. 1 of the present embodiment illustrates a case where a load is applied to the load receiving plate 3 by two bolts 7, the number of bolts 7 is not limited, and the arrangement position of the bolts 7 is not limited. , as long as it is in contact with the upper surface of the load receiving plate 3 .

Furthermore, in the present embodiment, the case where the upper surface of the load receiving plate 3 and the upper surface of the heat insulating wall member 5 are arranged at the same position in the stacking direction as shown in FIG. 2, the heat insulating wall member 5 is arranged so as to surround the laminate 2 and the heat insulating plate 4, and the upper surface of the load receiving plate 3 is arranged below the upper surface of the heat insulating wall member 5, so that the heat insulating wall member 5 and the upper surface of the load receiving plate 3 may be provided with a groove 5a containing the bolt 7. For example, as shown in FIG. . However, in the case of the configuration shown in FIG. 3 , the heat insulating plate 4 has such rigidity that it can apply the load applied from the tip surface 7 a of the bolt 7 via the load receiving plate 3 to the laminate 2 .

These relationships regarding installation positions and numbers also hold true in other embodiments described later.

(Second embodiment)
Next, an electrochemical cell stack according to a second embodiment will be described with reference to FIG. FIG. 4 is a schematic diagram of an electrochemical cell stack according to the second embodiment. Hereinafter, portions different from the first embodiment will be described, and other portions are assumed to be the same as in the first embodiment, and overlapping descriptions will be omitted.

The electrochemical cell stack 1 includes a laminate 2, a load receiving plate 3, a heat insulating plate 4, a heat insulating wall member 5, and a tightening band 16 as a load application mechanism. The difference between this embodiment and the first embodiment is that a tightening band 16 is provided instead of the fixing member 6 and bolt 7 .

The load receiving plate 3 is provided above the upper end plate 2 a of the laminate 2 with the heat insulating plate 4 interposed therebetween, and is arranged such that its upper surface is located above the upper surface of the heat insulating wall member 5 .

The tightening band 16 is provided on the outer periphery of the heat insulating wall member 5 and has a fastening portion 16a and a screw 16b. The tightening band 16 is made of a highly compressible material such as rubber. The tightening band 16 is designed such that its natural length is shorter than the circumference of the heat insulating wall member 5 . The tightening band 16 may be configured using, for example, a metal band.

The fastening portion 16 a is provided in the circumferential direction of the tightening band 16 . The fastening portion 16a has a screw hole for fastening a screw 16b, which will be described later.

The screw 16b is fastened to the screw hole of the fastening portion 16a. That is, the screw 16b is fastened to the threaded hole of the fastening portion 16a, and the fastening band 16 is wrapped around the outer periphery of the heat insulating wall member 5 and fixed. Since the tightening band 16 is wound and fixed around the outer periphery of the heat insulating wall member 5 while its full length is longer than its natural length, a restoring force acts so that the tightening band 16 returns to its natural length. Due to this restoring force, a tightening force is applied from the tightening band 16 to the heat insulating wall member 5 and the load receiving plate 3, so that a compressive load is applied to the laminate 2 from the upper surface of the load receiving plate 3 through the heat insulating plate 4. be done.

According to the above-described second embodiment, the tightening band 16 is provided on the outside of the heat insulating wall member 5, and the compressive load is applied from the load receiving plate 3 to the laminate 2 by the tightening force of the tightening band 16. As in the first embodiment, thermal deformation of the tightening band 16, which is a load application mechanism, can be prevented, and a load can be applied stably.

(Third embodiment)
Next, an electrochemical cell stack according to a third embodiment will be described with reference to FIG. FIG. 5 is a schematic diagram of an electrochemical cell stack according to the third embodiment. Hereinafter, portions different from those of the first or second embodiment will be described, and redundant description will be omitted as the other portions are the same as those of the first or second embodiment.

The electrochemical cell stack 1 includes a laminate 2, a load receiving plate 3, a heat insulating plate 4, a heat insulating wall member 5, and a cylinder 26 as a load application mechanism. The difference between this embodiment and the first and second embodiments is that instead of the fixing member 6 and bolt 7 in the first embodiment and the tightening band 16 in the second embodiment, a load applying mechanism is used as a load applying mechanism. A device 26 is provided.

The load application device 26 is arranged on the upper surface of the load receiving plate 3, and includes a fluid supply portion 26a, a cylinder 26b, a piston 26c, and a fluid discharge portion 26d.

The fluid supply portion 26a is a pipe that is connected to the cylinder 26b and supplies the fluid that is the source of the load to the cylinder 26b. The fluid supply portion 26a is provided with a flow control valve and a pressure control valve (not shown), and the pressure filling the cylinder 26b can be adjusted by throttling the pressure control valve. In this embodiment, the case where the fluid is oil will be described as an example, but the type and state of the fluid are not particularly limited, and gas may be used, for example.

The cylinder 26b is arranged above the load receiving plate 3 . A fitting portion (not shown) is provided on the lower end surface of the cylinder 26b, and the load receiving plate 3, the cylinder 26b, and the lower end surface are fitted through this fitting portion. A piston 26c is inserted into the cylinder 26b, and the upper and lower sides of the piston 26c are sealed to the extent that the piston 26c can move up and down. The upper side of the cylinder 26b is connected to the fluid supply portion 26a, and oil is supplied from the fluid supply portion 26a. On the other hand, the lower side of the cylinder 26b is sealed from the upper side of the cylinder 26b via the piston 26c. That is, the oil supplied from the fluid supply portion 26a does not leak to the lower side of the cylinder 26b, and is supplied only to the upper side of the cylinder 26b.

The fluid discharge portion 26d is a pipe that is connected to the upper side of the cylinder 26b and discharges the oil filled in the upper side of the cylinder 26b. A flow control valve (not shown) is provided in the fluid discharge portion 26d, and the amount of oil discharged from the upper side of the cylinder 26b can be adjusted. This flow control valve is normally closed, and opens according to the amount of oil that is discharged from the upper side of the cylinder 26b. A relief valve (holding pressure valve), other pressure regulating valves, check valves, or the like may be appropriately disposed in the fluid discharge portion 26d.

Next, the operation of this embodiment will be described. From the state where the upper side of the cylinder 26b is not filled with oil, a flow control valve (not shown) of the fluid supply section 26a is opened to supply a predetermined amount of oil from the fluid supply section 26a to the upper side of the cylinder 26b. When the upper side of the cylinder 26b is filled with oil, a downward load corresponding to the weight of the oil is applied to the piston 26c. In this state, by throttling the pressure regulating valve (not shown) of the fluid supply portion 26a, hydraulic pressure is applied to the piston 26c according to the weight of the oil and the throttling of the pressure regulating valve. When this hydraulic pressure overcomes the pressure applied to the piston 26c from the lower side of the cylinder 26b, the piston 26c moves downward, and the upper surface of the load receiving plate 3 fitted to the fitting portion (not shown) of the lower end surface of the cylinder 26b. Contact. As a result, a downward load is applied to the load receiving plate 3 via the piston 26c. When a predetermined amount of oil is supplied to the upper side of the cylinder 26b, the flow control valve (not shown) of the fluid supply section 26a is closed to stop the supply of oil from the fluid supply section 26a.

According to the above-described third embodiment, by using the load applying device 26 as the load applying mechanism, the same effects as those of the first and second embodiments can be obtained.

Although the present embodiment has been described by exemplifying the case where the heat insulating wall member 5 is provided as in the first and second embodiments, the electrochemical cell stack 1 of the present embodiment does not include the heat insulating wall member 5. may be configured.

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

1. electrochemical cell stack;2. laminate, 2a. upper end plate, 2b. lower end plate;3. 4. load bearing plate; 5. heat insulating plate; Insulating wall member 5a. groove, 6. fixing member, 6a. 7. bolt holes; bolt, 7a. tip face, 16 . tightening band, 16a. fastener, 16b. screw, 26. load application device, 26a. fluid supply, 26b. cylinder, 26c. piston, 26d. Fluid discharge

Claims (1)

a laminate in which a plurality of solid oxide single cells are laminated;
a heat insulating plate provided on at least one of the upper end surface and the lower end surface of the laminate in the stacking direction;
a load applying mechanism that applies a compressive load to the laminate by indirectly contacting the heat insulating plate;
a heat insulating wall member surrounding the laminate from the side surface of the heat insulating plate;
a load receiving plate between the heat insulating plate and the load applying mechanism;
The heat insulating plate and the load receiving plate are included in a hole provided in the heat insulating wall member ,
The load application mechanism is
a bolt whose screw tip abuts against the load receiving plate;
a fixing member having a bolt hole into which the bolt is screwed and fixed to the upper surface of the heat insulating wall member;
An electrochemical cell stack comprising:

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