WO2024195442A1

WO2024195442A1 - Fuel cell stack

Info

Publication number: WO2024195442A1
Application number: PCT/JP2024/006898
Authority: WO
Inventors: 大介和知; 一嘉宮島
Original assignee: 本田技研工業株式会社
Priority date: 2023-03-22
Filing date: 2024-02-27
Publication date: 2024-09-26

Abstract

This fuel cell stack comprises a limiting member that is disposed in a gap between an inner wall surface of a case and an outer side surface of a cell stack, the surfaces facing each other, and that limits the movement of the cell stack in a direction that is orthogonal to a predetermined direction. If, in the predetermined direction, a region where the limiting member is provided is defined as a first region and a region where the limiting member is not provided is defined as a second region, the limiting member is disposed so as to satisfy the relationship N < 2 × P × µ/(m × a), where N is the number of continuously stacked power generation cells in the second region, P is the compression load in the stacking direction, µ is the friction coefficient at the contact surface between the cell stack and a pair of end units, m is the mass of a single power generation cell, and a is the acceleration acting on the cell stack in a direction that is orthogonal to the predetermined direction.

Description

Fuel Cell Stack

The present invention relates to a fuel cell stack.

In recent years, fuel cell technology has been developed to contribute to energy efficiency, ensuring that more people have access to affordable, reliable, sustainable and advanced energy. One such fuel cell technology is a fuel cell stack made of multiple cells stacked together, and a technology has been known that prevents cells from shifting position when inertial forces act in a direction perpendicular to the stacking direction (see, for example, Patent Document 1). In the fuel cell stack described in Patent Document 1, a first restraining member for restraining the position of the stack is arranged on one side of the center in the stacking direction between the outer surface of the stack and the case, and a second restraining member is arranged on the other side.

Patent No. 6870603

However, in the fuel cell stack described in Patent Document 1, the restraining members are positioned without taking into account the mass of the cells, making it difficult to position the restraining members in the optimal position according to the inertial force.

A fuel cell stack, which is one aspect of the present invention, comprises a cell stack constructed by stacking in a predetermined direction power generating cells each having a membrane electrode structure including an electrolyte membrane and electrodes and a separator, a pair of end units arranged adjacent to one end face and the other end face of the cell stack in the predetermined direction, a case surrounding the cell stack and having one end and the other end fixed to the pair of end units respectively so that the cell stack is held in a state in which a predetermined compressive load is applied in the predetermined direction, and a limiting member arranged in the gap between the opposing inner wall surfaces of the case and the outer surface of the cell stack to limit movement of the cell stack in a direction perpendicular to the predetermined direction. The region where the restricting member is provided in a specified direction is defined as the first region, and the region where the restricting member is not provided is defined as the second region. Furthermore, the number of consecutive stacked power generation cells in the second region is defined as N, the specified compressive load is defined as P, the friction coefficient on the stacked surface of the power generation cells is defined as μ, the mass of a single power generation cell is defined as m, and the acceleration acting on the cell stack in a direction perpendicular to the specified direction is defined as a. The restricting members are positioned to satisfy the relationship N<2×P×μ/(m×a).

According to the present invention, the limiting member can be positioned in an optimal position according to the inertial force.

1 is a perspective view showing a schematic overall configuration of a fuel cell stack according to an embodiment of the present invention; FIG. 2 is a cross-sectional view taken along line II-II in FIG. 2 is a diagram for explaining the components of a force generated when an inertial force acts perpendicularly to the stacking direction of a cell stack included in the fuel cell stack of FIG. 1 . FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 2 . FIG. 5 is a diagram showing a modification of FIG. 4 .

Below, an embodiment of the present invention will be described with reference to Figures 1 to 5. A fuel cell stack according to an embodiment of the present invention constitutes the main element of a fuel cell. The fuel cell can be mounted, for example, in a vehicle and generate electricity to drive the vehicle. Fuel cells can also be mounted in moving objects other than vehicles, such as aircraft and ships, robots, and various industrial machines.

First, the overall configuration of the fuel cell stack will be described. FIG. 1 is a perspective view that shows a schematic overall configuration of a fuel cell stack 100 according to an embodiment of the present invention. For convenience, the three mutually orthogonal axial directions shown in the figure are defined below as the front-rear direction, the left-right direction, and the up-down direction, and the configuration of each part will be described according to these definitions. These directions are not necessarily the same as the front-rear direction, the left-right direction, and the up-down direction of the vehicle. For example, the front-rear direction in FIG. 1 may be the front-rear direction, the left-right direction, or the up-down direction of the vehicle.

As shown in FIG. 1, the fuel cell stack 100 has a cell stack 10, end units 20 arranged adjacent to both front and rear end faces of the cell stack 10, and a case 30 that surrounds the cell stack 10, and has an overall roughly rectangular parallelepiped shape.

The case 30 has four roughly rectangular side walls 31 that face the top, right, bottom, and left sides of the cell stack 10, respectively. These four side walls 31 form a roughly box-shaped storage space SP0 with open front and rear sides. The case 30 is made of a metal such as aluminum or iron. In addition to the metal end plates 21, the end unit 20 includes insulators and terminal plates between the end plates 21 and the front and rear end faces of the cell stack 10, and the front and rear of the case 30 are covered by the end units 20 (end plates 21).

In part A of FIG. 1, a portion of the side wall 31 of the case 30 is shown in a cutaway state. As shown in part A of FIG. 1, the cell stack 10 is formed by stacking a plurality of power generation cells 1 (for convenience, only a single power generation cell is shown) in the front-to-rear direction. The power generation cell 1 has a unitized electrode assembly 2 (UEA; unitized electrode assembly) having a membrane electrode assembly including an electrolyte membrane and an electrode, and separators 3 arranged on both the front and rear sides of the unitized electrode assembly 2 and sandwiching the unitized electrode assembly 2. The unitized electrode assemblies 2 and the separators 3 are arranged alternately in the front-to-rear direction. The number of stacked power generation cells 1 included in the cell stack 10 is the same as the number of integrated electrode assemblies 2.

Separator 3 has a pair of front and rear metal thin plates with a corrugated cross section, and is constructed as a single unit by joining the outer peripheries of the pair of thin plates. Separator 3 is made of a conductive material with excellent corrosion resistance, such as titanium, titanium alloy, or stainless steel. The pair of thin plates are formed into an uneven shape by press molding or the like so as to form a cooling flow path inside separator 3 through which a cooling medium (e.g. water) flows, and the power generation surface of power generation cell 1 is cooled by the flow of the cooling medium.

The separator 3 on the front side of the integrated electrode assembly 2 is, for example, an anode side separator (anode separator), and an anode flow path through which fuel gas containing hydrogen flows is formed between the anode separator 3 and the integrated electrode assembly 2. The separator 3 on the rear side of the integrated electrode assembly 2 is, for example, a cathode side separator (cathode separator), and a cathode flow path through which oxidant gas containing oxygen flows is formed between the cathode separator 3 and the integrated electrode assembly 2.

The integrated electrode assembly 2 has a membrane electrode assembly (MEA) and a resin frame that supports the periphery of the membrane electrode assembly. The integrated electrode assembly 2 is sometimes called a membrane electrode structure or membrane electrode member. The membrane electrode assembly has an electrolyte membrane, an anode electrode provided on the front surface of the electrolyte membrane, and a cathode electrode provided on the rear surface of the electrolyte membrane. The electrolyte membrane is, for example, a solid polymer electrolyte membrane. The anode electrode is an electrode catalyst layer formed on the front surface of the electrolyte membrane and serves as a reaction field for the electrode reaction, and a gas diffusion layer is provided on the front surface of the electrode catalyst layer to diffuse and supply the reactant gas. The cathode electrode is an electrode catalyst layer formed on the rear surface of the electrolyte membrane and serves as a reaction field for the electrode reaction, and a gas diffusion layer is provided on the rear surface of the electrode catalyst layer to diffuse and supply the reactant gas.

At the anode electrode, the fuel gas (hydrogen) supplied through the anode flow path and gas diffusion layer is ionized by the action of a catalyst and passes through the electrolyte membrane to move to the cathode electrode side. The electrons generated at this time pass through an external circuit and are extracted as electrical energy. At the cathode electrode, the oxidant gas (oxygen) supplied through the cathode flow path and gas diffusion layer reacts with the hydrogen ions guided from the anode electrode and the electrons that have moved from the anode electrode to generate water. The generated water provides an appropriate humidity to the electrolyte membrane, and excess water is discharged outside the integrated electrode assembly 2.

Through holes 211 to 216 are opened in the front end unit 20. Through hole 211 is a through hole for supplying fuel gas to the inside of the cell stack 10. Through hole 212 is a through hole for discharging cooling medium from the cell stack 10 to the outside. Through hole 213 is a through hole for discharging oxidant gas from the cell stack 10 to the outside. Through hole 214 is a through hole for supplying oxidant gas to the inside of the cell stack 10. Through hole 215 is a through hole for supplying cooling medium to the inside of the cell stack 10. Through hole 216 is a through hole for discharging fuel gas from the cell stack 10 to the outside.

A number of flow paths (manifolds) are formed at both left and right ends of the cell stack 10, extending in the front-rear direction so as to communicate with the through holes 211-216. Fuel gas supplied through the through hole 211 is guided to the anode flow path inside the cell stack 10, and oxidant gas supplied through the through hole 214 is guided to the cathode flow path. This allows power generation in the power generation cell 1. After supply, the fuel gas and oxidant gas are discharged from the cell stack 10 through the through

holes

216 and 213, respectively. A cooling medium supplied through the through hole 212 is guided to the cell stack 10, thereby cooling the power generation surface. The cooling medium that has passed through the cell stack 10 is discharged through the through hole 215.

The fuel cell stack 100 is assembled, for example, in the following manner. First, one of the end units 20 is placed on the top surface of an assembly table. Next, the case 30 is placed on the top surface of this end unit 20, and the end unit 20 is fastened to one end (lower end) of the case 30 using bolts. Furthermore, multiple power generation cells 1 are stacked and accommodated in the storage space SP0 inside the case through an opening in the top surface of the case 30. At this time, the power generation cells 1 are stacked while being positioned relative to the case 30 by guide members (not shown) that extend in the front-to-rear direction and are provided on the inner wall surface of the case 30.

Once a predetermined number of power generation cells 1 have been stacked, the other end unit 20 is mounted and a pressurizing machine is used to apply pressure from above to the entire stack. When the upper end unit 20 comes into contact with the other end (top end) of the case 30 as a result of the application of pressure, the end unit 20 and the other end of the case 30 are fastened together using bolts. This completes the assembly of the fuel cell stack 100. When the fuel cell stack 100 is assembled, it is held in a state in which a predetermined compressive load is applied to the cell stack 10 via the end unit 20.

When such a fuel cell stack 100 is mounted on a vehicle, an inertial force acts on the cell stack 10 in accordance with the acceleration acting on the vehicle. For example, when the stacking direction is in the left-right direction of the vehicle, if longitudinal acceleration acts on the vehicle when the vehicle accelerates and decelerates, an inertial force acts on the cell stack 10 in a direction perpendicular to the stacking direction. Also, when the stacking direction is in the front-rear direction of the vehicle, if lateral acceleration acts on the vehicle when the vehicle turns, an inertial force acts on the cell stack 10 in a direction perpendicular to the stacking direction.

In this way, an inertial force acts on the cell stack 10 during normal operation of the vehicle, but this is not limited to this, and an inertial force also acts on the cell stack 10 when an impact force acts on the vehicle from the outside. For example, when the stacking direction is the left-right direction of the vehicle, if the vehicle collides with an external object (e.g., another vehicle) and an impact acts from the front or rear by the external object, an inertial force acts on the cell stack 10 in a direction perpendicular to the stacking direction. Also, when the stacking direction is the front-rear direction of the vehicle, if the vehicle collides with an external object (e.g., another vehicle) and an impact acts from the right or left by the external object, an inertial force acts on the cell stack 10 in a direction perpendicular to the stacking direction. The inertial force acting during normal operation is called a normal inertial force, and the inertial force acting when an impact force acts from an object outside the vehicle is sometimes called an abnormal inertial force. The abnormal inertial force may be larger than the normal inertial force.

When an inertial force acts on the cell stack 10 in a direction perpendicular to the stacking direction, the center of the cell stack 10 in the stacking direction is deformed into a bow shape. At this time, a shear force acts on the stacking surface of the cell stack 10, which may cause misalignment at the stacking surface of the cell stack 10 (e.g., the boundary surface with the end unit 20). Taking this into consideration, in this embodiment, a limiting member 50 is provided that limits the movement of the cell stack 10 to prevent deformation and misalignment of the cell stack 10 in the direction perpendicular to the stacking direction.

In FIG. 1, a restricting member 50 is provided in the center of the case 30 in the front-to-rear direction. FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1. For convenience, FIG. 2 shows only the outline of the cell stack 10. As shown in FIG. 2, a gap SP1 is provided around the entire circumference of the cell stack 10 between the inner surface 30a of the case 30 and the outer surface 10a of the cell stack 10. The restricting members 50 are provided at the four corners of the case 30, i.e., the corners where the upper and lower side walls 31 intersect with the left and right side walls 31, so as to close the gap SP1.

More specifically, an opening 32 is provided at the corner of the case 30 over a predetermined length in the front-rear direction (stacking direction). The restricting member 50 has a cover 51 configured with a substantially L-shaped cross section corresponding to the corner of the case 30, and a buffer 52 attached to the inner surface of the cover 51. The cover 51 is made of a metal that is one size larger than the opening 32. The buffer 52 is an elastic body such as a resin material or rubber, and is made of an insulator. The buffer 52 is, for example, bonded to the inner surface of the cover 51 and is provided integrally with the cover 51. The buffer 52 can be inserted into the gap SP1 through the opening 32, and is configured with a substantially L-shaped cross section corresponding to the shape of the corner of the outer surface 10a of the cell stack 10.

The cover 51 has through holes 53 at both ends, sandwiching the corners. The cover 51 also has through holes 53 at both ends in the front-rear direction (see FIG. 1). The case 30 has screw holes 33 near the opening 32, corresponding to the through holes 53. The cover 51 is attached to the case 30 from the outside so as to cover the entire opening 32. More specifically, the cover 51 is fixed to the outer surface 31b of the side wall 31 by screwing bolts 55 inserted through the through holes 53 into the screw holes 33. Although not shown in the figure, a sealant is interposed at the contact surface between the cover 51 and the outer surface 31b of the side wall 31, and the cover 51 is attached to the side wall 31 in a sealed state via the sealant.

When the cover 51 is attached to the case 30, the buffer 52 is positioned inside the opening 32 without interfering with the case 30. At this time, the buffer 52 is pressed against the corner of the cell stack 10 by the fastening force of the bolt 55, and the gap SP1 between the corner of the case 30 and the corner of the cell stack 10 is blocked by the buffer 52. As a result, the compressed buffer 52 is interposed in the gap SP1 between the corner of the highly rigid case 30 and the corner of the cell stack 10. Therefore, the restricting member 50 restricts the cell stack 10 in the vertical and horizontal directions, making it possible to limit the movement of the cell stack 10 when an inertial force acts on the cell stack 10.

Since the restricting member 50 is disposed in the gap SP1 in this manner, it is possible to suppress displacement of the cell stack 10 in the shear direction (up-down direction, left-right direction) when an inertial force acts on the cell stack 10. However, if the restricting member 50 is disposed over the entire length of the stacking direction (front-back direction) of the cell stack 10, this would be wasteful and would result in an increase in the weight of the entire fuel cell stack. Therefore, in this embodiment, the fuel cell stack 100 is configured as follows so that the restricting member 50 can efficiently suppress displacement of the cell stack 10 when an inertial force acts on the cell stack 10, particularly displacement due to slippage of the cell stack 10 on the stacking surface.

Figure 3 is a diagram explaining the force components that are generated when an inertial force acts perpendicular to the stacking direction of the cell stack 10 when there is no restricting member 50. As shown in Figure 3, when an impact force G acts to the left on the vehicle body, i.e., the case 30, an inertial force F acts to the right on the cell stack 10, causing the cell stack 10 to deform into a bow shape as shown by the two-dot chain line in Figure 3. At this time, a shear force acts on the cell stack 10, and the shear force is maximum (=F/2) at both front and rear end surfaces of the cell stack 10, that is, at the boundary surface between the cell stack 10 and the end unit 20 (e.g., a terminal plate).

On the other hand, a frictional force Fs against the maximum shear force F/2 acts on both front and rear end surfaces of the cell stack 10. If the compressive load in the front and rear direction applied when stacking the cell stack 10 is P and the friction coefficient (e.g., static friction coefficient) at the boundary surface between the cell stack 10 and the end unit 20 is μ, the frictional force Fs is P×μ. The friction coefficient μ is the same or approximately the same as the friction coefficient of the stacking surface of the cell stack 10. If the mass of each set of power generation cells 1 is m, the number of stacks of the cell stack 10 is N, and the acceleration of the cell stack 10 is a, the inertial force F is m×N×a. For example, the acceleration a is the acceleration when an abnormal inertial force larger than the normal inertial force acts on the vehicle. As an example, the acceleration a is 50 m/s2.

Here, if the friction force Fs is smaller than the maximum shear force F/2 (Fs<F/2), slippage occurs at both front-rear end surfaces of the cell stack 10. In other words, when the following formula (I) is established, the cell stack 10 shifts due to inertial force.
P×μ<m×N×a/2...(I)

By rearranging the above formula (I), the following formula (II) is obtained.
2×P×μ/(m×a)<N...(II)

In other words, if the number of stacks N of the power-generating cells 1 is greater than the value (2Pμ/ma) shown on the left side of the above formula (II), slippage will occur at the end face of the cell stack 10, but if it is smaller, slippage will not occur. The number of stacks in this case, that is, the number of stacks calculated by the left side of the above formula (II), is called the limit number of stacks N0. In this embodiment, the limiting member 50 is positioned so that the number of stacks N of the cell stack 10 that is not limited by the limiting member 50 is less than the limit number of stacks N0.

FIG. 4 is a diagram showing an example of the arrangement of the restricting member 50 included in the fuel cell stack 100 according to this embodiment, and corresponds to a cross-sectional view taken along line IV-IV in FIG. 2. As shown in FIG. 4, the restricting member 50 is arranged in the center of the cell stack 10 in the front-rear direction. Hereinafter, the area AR1 in which the restricting member 50 is arranged will be referred to as the restricting area, and the area AR2 in which the restricting member 50 is not arranged will be referred to as the non-restricting area. In FIG. 4, non-restricting areas AR2 are provided on both the front and rear sides of the restricting area AR1. In this case, the number N of stacked power generating cells 1 in both the front and rear non-restricting areas AR2 is set to be less than the limit stacking number N0.

For example, if the total number of power generating cells 1 is 400 and the calculation result of the left side of the above formula (II) is 156.9, the number N of stacked power generating cells 1 in the front and rear non-restricted areas AR2 is set to 156. In this case, the number N of stacked cells in the restricted area AR1 is 88. This makes it possible to suppress slippage of the cell stack 10 at both front and rear end surfaces of the non-restricted area AR2, i.e., misalignment of the stacked surface of the cell stack 10 due to inertial force F. In the example of Figure 4, the length of the restricted area AR1 can be minimized. As a result, the size (front-rear length) of the limiting member 50 can be minimized, and costs can be reduced.

FIG. 5 shows a modified example of FIG. 4. In FIG. 5, restricting members 50 are arranged at both ends of the cell stack 10 in the front-rear direction. Thus, restricted areas AR1 are provided at both ends of the cell stack 10 in the front-rear direction, and a non-restricted area AR2 is provided in the center in the front-rear direction. In this case as well, the number N of stacked power generating cells 1 in the non-restricted area AR2 is set to be less than the limit number N0.

For example, if the total number of power generating cells 1 is 400 and the calculation result of the left side of the above formula (II) is 156.9, the number N of stacked power generating cells 1 in the central unrestricted area AR2 is set to 156. At this time, the number N of stacked cells in the front and rear restricted areas AR1 are both set to 122. This makes it possible to suppress slippage of the cell stack 10 at both front and rear end surfaces of the unrestricted area AR2.

In the example of Figure 5, the restricting member 50 is provided in connection with the front and rear end units 20, so that the opening 32 (Figure 2) of the case 30 can be easily processed. In addition, the restricting member 50 is provided facing both ends of the case 30 in the front-rear direction, so that the restricting member 50 can be easily positioned. For example, it is possible to insert the restricting member 50 into the gap SP1 through the opening faces at both ends of the case 30 in the front-rear direction.

According to this embodiment, the following advantageous effects can be obtained.
(1) The fuel cell stack 100 comprises a cell stack 10 constructed by stacking in the fore-and-aft direction power-generating cells 1, each having an integrated electrode assembly 2 including an electrolyte membrane and an electrode, and a separator 3; a pair of end units 20 arranged adjacent to the front and rear end faces, respectively, of the cell stack 10; a case 30 surrounding the cell stack 10 and having its front and rear ends fixed to the pair of end units 20, respectively, so that the cell stack 10 is held in a state in which a predetermined compressive load is applied in the fore-and-aft direction; and a limiting member 50 arranged in a gap SP1 between the opposing inner wall surface 31a of the case 30 and the outer surface 10a of the cell stack 10, for limiting movement of the cell stack 10 in a direction perpendicular to the fore-and-aft direction ( FIGS. 1 and 2 ). The limiting member 50 is arranged so as to satisfy the relationship N<2×P×μ/(m×a) (formula (II) above) (Figures 4 and 5), where the region in the front-rear direction where the limiting member 50 is provided is defined as a restriction region AR1 (first region), and the region in which the limiting member 50 is not provided is defined as a non-restriction region AR2 (second region).Furthermore, when the number of consecutively stacked power generating cells 1 in the non-restriction region AR2 is defined as N, a predetermined compressive load is defined as P, the friction coefficient at the stacking surface of the power generating cells 1 is defined as μ, the mass of a single power generating cell 1 is defined as m, and the acceleration acting on the cell stack 10 in a direction perpendicular to the front-rear direction is defined as a.

This configuration allows the restricting member 50 to be appropriately positioned, and prevents the cell stack 10 from slipping due to inertial forces. In other words, it is possible to determine the maximum number of stacked power generating cells 1 that will not cause slippage in the cell stack 10 (the maximum number of stacked cells less than the limit number of stacked cells N0), so the restriction area AR1 can be set efficiently and without waste, and unnecessary placement of the restricting member 50 can be prevented.

(2) The non-restricted area AR2 is a pair of non-restricted areas AR2 that respectively include the front and rear ends of the gap SP1, and the restricted area AR1 is an area sandwiched between the pair of non-restricted areas AR2 (FIG. 4). This allows the range of the restricted area AR1 to be minimized, thereby reducing costs.

(3) The restricted area AR1 may be a pair of restricted areas AR1 each including a front end and a rear end of the gap SP1, and the non-restricted area AR2 may be an area sandwiched between the pair of restricted areas AR1 (FIG. 5). This allows the restricting member 50 to be positioned at both ends of the case 30 where the gap SP1 is easily accessible from the outside, making it easy to position the restricting member 50.

The above embodiment can be modified in various ways. In the above embodiment, the restricting member 50 is attached to the case 30 from the outside of the case 30, but the configuration of the restricting member is not limited to this. For example, a cover 51 that covers the opening 32 can be placed inside the case 30, and the restricting member can be configured not to protrude from the outer surface 31b of the side wall 31 of the case 30. In the above embodiment, the restricting members 50 are placed at the four corners of the case 40, but they may be placed at two opposing corners. The restricting member may be placed at a location other than the corners. The restricting member may be fixed to the gap SP1 between the inner wall surface 31a of the case 30 and the outer surface 10a of the cell stack 10 using fixing means other than bolts.

In the above embodiment (FIGS. 4 and 5), one of the restricted area AR1 and the non-restricted area AR2 is a single area, but the restricted area AR1 (first area) and the non-restricted area AR2 (second area) may be provided alternately in multiples. In this case, the number of stacked power generation cells 1 in the non-restricted area AR2 may be set so as to satisfy the above formula (II). In the above embodiment, the stack (cell stack 10) is formed by stacking the integrated electrode assemblies 2 and separators 3 as membrane electrode structures including an electrolyte membrane and electrodes alternately in the front-rear direction (predetermined direction), but the stacking direction is not limited to the front-rear direction and may be the up-down direction.

The above describes an example in which the fuel cell stack 100 is mounted on a vehicle, but the fuel cell stack can also be mounted on other moving objects. In this case, too, the limiting member should be positioned to satisfy the relationship in formula (II) above, taking into account the inertial force acting on the moving object.

The above description is merely an example, and the present invention is not limited to the above-mentioned embodiment and modifications as long as the characteristics of the present invention are not impaired. It is also possible to arbitrarily combine one or more of the above-mentioned embodiment and modifications, and it is also possible to combine modifications together.

1 Power generation cell, 2 Integrated electrode assembly, 3 Separator, 10 Cell stack, 20 End unit, 30 Case, 50 Restriction member, 100 Fuel cell stack, AR1 Restricted area, AR2 Non-restricted area

Claims

a cell stack formed by stacking, in a predetermined direction, power generating cells each having a membrane electrode assembly including an electrolyte membrane and an electrode and a separator;
a pair of end units arranged adjacent to one end surface and the other end surface of the cell stack in the predetermined direction,
a case that surrounds the cell stack and has one end and the other end fixed to the pair of end units so that the cell stack is held in a state in which a predetermined compressive load is applied in the predetermined direction;
a limiting member that is disposed in a gap between an inner wall surface of the case and an outer surface of the cell stack that face each other, and that limits movement of the cell stack in a direction perpendicular to the predetermined direction;
A region in the predetermined direction in which the limiting member is provided is defined as a first region, and a region in which the limiting member is not provided is defined as a second region. Furthermore, the number of consecutive stacked power-generating cells in the second region is defined as N, the predetermined compressive load is defined as P, the coefficient of friction at the contact surfaces between the cell stack and the pair of end units is defined as μ, the mass of a single power-generating cell is defined as m, and the acceleration acting on the cell stack in a direction perpendicular to the predetermined direction is defined as a,
N<2×P×μ/(m×a)
The limiting member is disposed so as to satisfy the relationship:
2. The fuel cell stack according to claim 1,
A fuel cell stack characterized in that the second region is a pair of second regions each including one end and the other end of the gap in the specified direction, and the first region is a region sandwiched between the pair of second regions.
2. The fuel cell stack according to claim 1,
A fuel cell stack characterized in that the first region is a pair of first regions each including one end and the other end of the gap in the specified direction, and the second region is a region sandwiched between the pair of first regions.