JP2006501601A - Compact fuel cell configuration - Google Patents

Abstract

The electrochemical fuel cell stack includes a plurality of fuel cells arranged in a stacked configuration to form a fuel cell assembly. The fuel cell assembly has first and second ends and defines a length between the ends. First and second end plates are disposed at the first and second ends of the fuel cell assembly, respectively. The stack has at least one side plate having first and second ends attached to first and second end plates, respectively. The side plates hold the first and second end plates in a spaced relationship such that the first and second end plates impart a compressive force to the fuel cell assembly. The side plate covers the fuel cell assembly between the first and second end plates and also provides a protective covering for the fuel cell assembly.

Description

  The present invention relates to a fuel cell, and more particularly to a fuel cell arranged in a stack and held in a compressed state.

  A fuel cell stack typically comprises a plurality of fuel cells in which one cell is stacked on top of another cell and held compressed together. The plurality of stacked fuel cells form a compressed fuel cell assembly to hold the plurality of fuel cells in a compressed state. Each fuel cell typically includes an anode layer, a cathode layer, and an electrolyte interposed between the anode layer and the cathode layer. Fuel cell assemblies require a significant amount of compressive force to force the fuel cells in the stack together. The need for compressive force comes from the internal gas pressure of the reactants in the fuel cell and the need to maintain good electrical contact between the internal components of the cell. In general, the unit force per area is generally about 1344 kPa to about 1413 kPa (about 195 to about 205 psi), which is evenly distributed over the entire active area of the battery (typically automobile size). About 0.05 square meters to about 0.1 square meters (77 to 155 square inches), so for fuel cells having an area of about 0.052 square meters (about 80 square inches), these sizes A typical overall compression force of the stack is from about 7031 kg to about 7484 kg (about 15,500 lbs to 16,500 lbs).

  Conventional fuel cell stack configurations have focused on the use of rigid end plates and tie rods to apply and maintain a compressive force on the fuel cell assembly. A plurality of fuel cells or fuel cell assemblies to be compressed are interposed between a pair of rigid end plates. The end plates are then compressed together by a tie rod that extends through or around the end plate and imparts a compressive force to the end plate. In addition, tie rods typically extend beyond the surface of the end plate, thereby increasing the volume of the stack configuration. When the stack configuration utilizes a rod distributed around the periphery of the end plate to distribute the compression force to the fuel cell assembly, proper tightening of the tie rods to distribute the desired compression force is: It becomes difficult. That is, the tie rods are tightened into a predetermined pattern in an attempt to evenly distribute the compression load to the fuel cell assembly. However, as each tie rod is tightened, the compression load delivered by each end plate changes, thereby re-creating each tie rod multiple times in an iterative process to achieve a substantially uniform compression force on the fuel cell assembly. It must be tightened. In addition, tie rods typically extend beyond the surface of the end plate, thereby increasing the volume of the stack configuration.

  A typical application in which fuel cells are used requires that the fuel cell assembly be covered with a protective casing. A typical protective casing is applied across existing stack configurations, adding volume to the entire stack configuration. Thereby, the protective casing increases the size of the stack configuration. In this state, the increase in size does not provide any utility other than the protection provided thereby. Since fuel cells are typically used in space-filled applications, it is desirable to provide a fuel cell contained within a protective casing having a minimum volume.

  Therefore, it would be advantageous to provide a stack configuration that can more easily apply compressive force to the fuel cell assembly, and even more advantageous if the compressive force applying means provides a minimum volume to the stack configuration. Furthermore, it would be advantageous to provide a protective casing for a fuel cell assembly that adds a minimum volume to the stack configuration, where the protective covering provides an advantage to the stack configuration in addition to protecting the fuel cell assembly. Is even more advantageous.

  The present invention relates to an apparatus and method for providing a compact fuel cell configuration for compressing a fuel cell assembly. In addition to compressing the fuel cell assembly, the apparatus can also provide a protective covering for the fuel cell assembly.

  The electrochemical fuel cell stack of the present invention comprises a plurality of fuel cells arranged in a stacked configuration to form a fuel cell assembly. The fuel cell assembly has first and second ends and defines a length between the ends. First and second end plates are disposed at the first and second ends of the fuel cell assembly, respectively. Side walls having first and second ends are attached to the first and second end plates, respectively. The sidewalls hold the first and second end plates in a spaced relationship such that the first and second end plates impart a compressive force to the fuel cell assembly.

  The first and second end plates of the side wall have first and second end plates so that the compression force applied to the fuel cell assembly by the first and second end plates has a predetermined magnitude. May be attached to each. Alternatively, the first and second end portions of the sidewall may be attached to the first and second end plates, respectively, such that the length of the fuel cell assembly is compressed by a predetermined distance.

  Preferably, the first and second end plates each have a peripheral side wall that forms a periphery of the end plate and is substantially parallel to the length of the fuel cell assembly. The first and second end portions of the sidewalls are attached to the peripheral sidewalls on the respective first and second end plates.

  In a first preferred embodiment, the first and second end plates are generally rectangular end plates with first and second pairs of side walls defining the perimeter of each of the end plates. It is. The side wall is one of a plurality of side plates, and at least one side plate of the plurality of side plates is attached to one side wall of the first pair of side walls, and the plurality of side plates At least one side plate is attached to a different pair of side walls of the first pair of side walls.

  Preferably, the first and second ends of the side walls are secured to the first and second end plates using mechanical fasteners. Even more preferably, the sidewall comprises a slot for receiving a mechanical fastener.

  In a second preferred embodiment, the electrochemical fuel cell stack comprises a plurality of fuel cells arranged in a stacked configuration to form a fuel cell assembly, the fuel cell assembly comprising first and second fuel cell assemblies. Having ends and defining a length between the ends; First and second end plates are disposed at the respective first and second ends and impart a compressive force to the fuel cell assembly. The side walls are attached to the first and second end plates. The sidewall has a first and second end attached to each first and second end plate. The sidewall covers a portion of the fuel cell assembly between the first and second end plates and provides a protective covering for the fuel cell assembly. Preferably, the side walls are attached to the end plates such that the end plates are held in spaced relation to distribute the compressive force on the fuel cell assembly.

Preferably, the sidewall provides a shield against electromagnetic interference to the fuel cell assembly. Even more preferably, one side wall is electrically grounded.
Optionally, but preferably, the sidewall is a plurality of side plates. Each side plate of the plurality of side plates covers a different side of the fuel cell assembly between the first and second end plates, and the fuel cell assembly between the first and second end plates. The whole is covered with a plurality of side plates.

  The method of making an electrochemical fuel cell stack of the present invention includes: (1) a first end of a fuel cell assembly is adjacent to a first end plate, and a second end of the fuel cell assembly is a second. A fuel cell assembly disposed between the first and second end plates in a state adjacent to the end plate, and (2) at least one of the end plates such that the fuel cell assembly is compressed. And (3) the first and second side walls so that the first and second end plates maintain a fixed spaced apart relationship to provide the internal compressive force. In a mode in which the end portion is attached to each of the first and second end plates, the side wall is attached to the end plate, and (4) each step of removing the external compressive force applied to the end plate is provided.

  Preferably, but optionally, the step of applying an external compressive force comprises the step of applying an external compressive force of a predetermined magnitude, and the step of attaching the side walls includes the first and second steps when the compressive force is removed. The first and second end portions of the side wall are respectively arranged so that the second end plate maintains a fixed spaced relationship and distributes a predetermined amount of internal compressive force to the fuel cell assembly. Attaching to the first and second end plates. As an alternative, the step of applying an external compressive force comprises the step of applying a compressive force to the end plate so that the fuel cell assembly is compressed a predetermined distance along the length direction. The attaching step includes a first and a second, respectively, such that when the external compressive force is removed, the first and second end plates maintain a fixed spaced apart relationship. Attaching the first and second end portions of the sidewall to the end plate.

  Optionally, but preferably, the side wall encloses a length of fuel cell assembly between the first and second end plates such that the side wall provides a protective covering for the fuel cell assembly.

  Further areas where the present invention is applicable will become apparent from the detailed description provided below. While preferred embodiments of the invention are shown, it should be understood that the detailed description and specific examples are given for purposes of illustration only and are not intended to limit the scope of the invention. It is.

  The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

The following description of the preferred embodiment is merely exemplary in nature and is not intended to limit the invention, its application, or how it is used.
Referring to FIGS. 1 and 2, an electronic scientific fuel cell stack 20 according to a preferred embodiment of the present invention is shown. The fuel cell stack 20 includes a plurality of fuel cells 22 arranged in a stacked configuration to form a fuel cell assembly 24 having an upper end 26 and a lower end 28 at both ends. As shown in FIG. 10A, the stack has a compressed length 30 and an uncompressed length 31 between the upper and lower ends. The fuel cell assembly 24 is interposed between the upper and lower end assemblies 32, 34. The upper and lower end assemblies 32, 34 are held in a fixed spaced relationship by the side walls. In the presently preferred embodiment, the sidewall comprises at least one side plate 36. The side plate 36 holds the upper and lower assemblies 32, 34 in a spaced relationship such that the upper and lower end assemblies 32, 34 distribute compressive force to the fuel cell assembly 24. Yes. In accordance with known fuel cell technology, the fuel cell stack 20 includes an inlet 34, an outlet 38, and passages (not shown) for supplying and discharging reactant and coolant fluid flows to and from the fuel cell assembly 24. And comprising.

  As can be seen in FIG. 4, the fuel cell assembly 24 includes a multi-repetitive unit or fuel cell 22 having an MEA 40, a pair of bipolar plate assemblies 42 disposed on both sides of the MEA 40, and Is provided. Each bipolar plate assembly 42 is composed of a coolant distribution layer 42c interposed between two gas distribution layers 42g. Intervening between the coolant distribution layer 42c and the gas distribution layer 42g is an impervious separator plate 44 that contains a coolant and separates the anode and cathode gas flows. In the fuel cell 22, the MEA 40 is interposed between the anode gas distribution layer 42ga of one cell and the cathode gas distribution layer 42gc of the cell adjacent thereto. The MEA 40 can take a variety of forms, as is known in the art. For example, the MEA 40 can be a polymer electrolyte membrane. Preferably, the polymer electrolyte membrane is a thin reinforcing membrane having a thickness on the order of about 0.018 microns. This thin reinforced polymer electrolyte membrane is much thinner than the polymer electrolyte membrane used in prior art fuel cells having a thickness of about 0.007 inches. The thin reinforced polymer electrolyte membrane used in the present invention accounts for a smaller percentage of the length 30 of the fuel cell assembly 24 and is significantly smaller than the thicker polymer electrolyte membrane used in prior art fuel cell stacks. Shows slip or stress relaxation properties.

  The fuel cells 22 are arranged in a stacked configuration to form a fuel cell assembly 24. The number of fuel cells 22 stacked adjacent to each other to form the fuel cell assembly 24 can be varied. At least one of the fuel cells 22 utilized to form the fuel cell assembly 24 depends on the needs of the fuel cell stack 20. That is, when a larger or more powerful fuel cell stack 20 is desired, the number of fuel cells 22 in the fuel cell assembly 24 is increased. As is known in the art, the fuel cell 22 needs to be compressed so that the fuel cell 22 is more efficient and generates more power. Thus, the fuel cell assembly 24 is compressed between the upper and lower end assemblies 32 and 34. Preferably, the activation region (not shown) of the fuel cell assembly 24 is uniformly compressed within the fuel cell assembly 24 to maximize the efficiency of the fuel cell assembly 24 and each of the fuel cells 22.

  Referring again to FIGS. 2 and 3, the upper end assembly 32 is disposed adjacent to the upper end 26 of the fuel cell assembly 24. Upper end assembly 32 includes an upper end plate 45 having both an inner surface 46 and an outer surface 48. The inner side surface 46 of the upper end plate 45 faces the upper end portion 26 of the fuel cell assembly 24. The upper end plate 45 has a number of openings 50 that allow the inlet 37 and outlet 38 connected to the fluid passages to extend from the fuel cell assembly 24 to the outside of the fuel cell stack 20. The end of the fuel cell stack 20 having the inlet 37 and the outlet 38 connecting the passages is also referred to as “wet end”.

  The lower end assembly 34 is disposed adjacent to the lower end 28 of the fuel cell assembly 24. Lower end assembly 34 includes a lower end plate 58 having both an inner surface 60 and an outer surface 62. The lower end plate 58 is arranged such that the inner surface 60 of the lower end plate 58 faces the lower end 28 of the fuel cell assembly 24. When there are no inlets and outlets through the lower end assembly 34 that connect to the fluid passage, the lower end 28 of the fuel cell stack 20 is also referred to as a “dry end”.

  Optionally, in the preferred example, one or more spacer plates 52 may be disposed between the fuel cell assembly 24 and the upper and / or lower end plates 45,58. The spacer plate 52 has an inner surface 54 of the spacer plate 52 facing the ends 26, 28 of the fuel cell assembly 24 and an outer surface 55 of the spacer plate 52 facing the inner surfaces 54, 60 of the end plates 45, 58. In the faced state, it is disposed between the end plates 45 and 58 and the end portions 26 and 28 of the fuel cell assembly 24. When the terminal plate 56 is disposed at the end portions 26, 28 of the fuel cell assembly 24, the spacer plate 52 is positioned between the terminal plate 56 and the end portion with the inner surface 54 of the spacer plate 52 facing the terminal plate 56. It is arranged between the plates 45 and 58. The spacer plate 52 separates the end plates 45, 58 from the terminal plate 56. The spacer plate 52 is disposed within the end assemblies 32, 34 such that the thickness 57 of the spacer plate 52 is aligned with the length 30 of the fuel cell assembly 24. Although a preferred embodiment has been shown in connection with the upper and lower end assemblies 32, 34, those skilled in the art will recognize that the number and location of the spacer plates 52 will vary depending on the design and application of the fuel cell stack 20. You will admit that you can.

  Upper end plate 45 and lower end plate 58 each have a peripheral sidewall 64 that separates inner surfaces 46, 60 from outer surfaces 48, 62. The peripheral side walls 64 of the upper end plate 45 and the lower end plate 58 are aligned with the length 30 of the fuel cell assembly 24. Preferably, as shown in the drawings, the fuel cell stack 20 is substantially rectangular in shape, and the upper and lower end plates 45 and 58 are substantially perpendicular to each other. The two side walls 66 and 68 are formed. The first and second pairs of side walls 66, 68 include one or more threaded bores that receive threaded fasteners 80 for securing the side plate 36 to the upper end plate 45 and the lower end plate 58. 70 each.

As described above, the upper end plate 32 and the lower end plate 34 impart a compressive force to the fuel cell assembly 24. The compressive force applied to the fuel cell assembly 24 is generated by maintaining the upper end plate 45 and the lower end plate 58 in a fixed spaced apart relationship. Preferably, the upper end plate 45 and the lower end plate 58 are held in a spaced apart relationship by the side plate 36. Each side plate 36 has first and second ends 72, 74 that define a length 76 therebetween. Each side plate 36 has a first end 72 adjacent to the upper end plate 45 with the direction of the length 76 of the side plate 36 aligned with the direction of the length 30 of the fuel cell assembly 24, The fuel cell stack 20 is coordinated such that the second end 74 is adjacent to the lower end plate 58. Optionally but preferably, the side plate 36 extends along a peripheral side wall 64 across the end plates 45, 58. The first and second ends 72, 74 of each side plate 36 are threaded bores 70 on the peripheral side walls 64 of the upper and lower end plates 45, 58 when the fuel cell assembly 24 is compressed. One or more aligned openings 78 are provided. Preferably, the openings 78 of either the first and / or second end 72, 74 of each side plate 36 are spaced apart by a fixed distance between the upper and lower end plates 45, 58. It is in the form of a slot so that it can be held in relationship. The slot can still hold the upper and lower end plates 45, 58 in a fixed spaced relationship, while allowing the size of various components of the fuel cell stack 20 to be changed. To do. Although threaded mechanical fasteners 80 are preferably used to attach the side plate 36 to the upper and lower end plates 45, 58, those skilled in the art will consider the side plate 36 to be upper and lower. It will be appreciated that other means of attaching to the end plates 45, 58 of the present invention can be used without departing from the scope of the invention as defined by the claims. In this regard, the joint formed by the side plate 36 and the upper and lower end plates 45, 58 should be sufficient to withstand relative rotation at the interface between them. For example, the first and / or second ends 72, 74 of the side plate 36 may be other mechanical fastening means such as rivets or pins, and various coupling means such as housing, welding, blaze welding or adhesive bonding Through and can be secured to the respective upper and / or lower end plates 45, 58 and still be within the scope of the present invention. Furthermore, it should be understood that one of the ends 72, 74 of the side plate 36 can be bent to form a retaining element (not shown). This holding element holds the end plates 45, 58 while fixing the end plates 45, 58 while the opposite ends 72, 74 of the side plate 36 are attached to the opposing end plates 45, 58. To maintain a spaced relationship, it can be placed on one of the end plates 45, 58.
Each side plate 36 can have one or more openings 82 as desired. The opening allows the terminal block 83 of the terminal plate 56 to extend outside the fuel cell stack 20. Preferably, each side plate 36 is electrically grounded to protect the fuel cell assembly 24 against electromagnetic interference. It is also preferred that each side plate 36 be made from metal. The side plate 36 used to hold the upper and lower end plates 45, 58 in a fixed spaced relationship has a fixed spaced relationship between the upper and lower end plates 45, 58. While maintaining, the upper and lower end plates 45, 58 are dimensioned to distribute and maintain a compressive force on the fuel cell assembly 24. Due to the relatively large width of the side plate 36, a relatively small thickness is required to provide the necessary tensile strength to carry the compressive force. This aspect of the present invention represents a weight saving over the prior art that uses an axial rod that extends around and / or passes through the fuel cell assembly.

  Preferably, the one or more side plates 36 cover at least a portion of the fuel cell assembly 24 to protect the fuel cell assembly 24 against accidental damage. Even more preferably, the side plate 36 covers the entire fuel cell assembly 24 and provides a protective cover for the fuel cell assembly 24 and the fuel cell stack 20. Thus, the side plate 36 protects the fuel cell assembly 24 and the fuel cell stack 20 from damage as a result of impacts, strikes or other impacts, while the side plates 36 provide impact, strikes and various other effects. Dimensions are set so that they can withstand the bruises of nature. In this embodiment, the side plate 36 serves to distribute and maintain a compressive load on the fuel cell assembly 24 so as to hold the upper and lower end assemblies 45, 58 in a fixed spacing relationship. As well as a protective covering for the fuel cell assembly 24 and the fuel cell stack 20. By using a side plate 36 that performs a protective function, the fuel is provided on the fuel cell stack 20 to provide protection against accidental blows, impacts or blows, as is done with conventional fuel cell stacks. There is no need to have additional configurations placed around the battery stack 20.

  The spacer plate 52, optionally included in the upper end assembly 32 and / or the lower end assembly 34, serves a variety of purposes. That is, the spacer plate 52 can be included in the fuel cell stack 20 for one or more reasons. For example, the spacer plate 52 can be used to separate the upper and / or lower end plates 45, 58 from the terminal plate 56. As described above, the terminal plate 56 is electrically conductive and is used to extract current from the fuel cell stack 20 through the terminal block 83. When the upper and / or lower end plates 45, 58 are electrically conductive, the spacer plate 52 disposed between the upper and / or lower end plates 45, 58 and the terminal plate 56 is: The upper and / or lower end plates 45, 58 can be electrically isolated from the terminal plate 56. The spacer plate 52 can also be used to adjust the overall dimensions of the fuel cell stack 20. That is, one or more spacer plates 52 can be disposed between the fuel cell assembly 24 and the upper and / or lower end plates 45, 58, as will be described in detail below. A fuel cell stack 20 having a predetermined length is provided while 32 and 34 still apply a compressive force to the fuel cell assembly 24. Currently preferably, the spacer plate 52 has a thickness 57 in the range of about 8-18 millimeters to provide adequate electrical insulation and uniform dimensions of the fuel cell stack 20. However, those skilled in the art will recognize that specific application and design details require a range of thicknesses 57 for the spacer plate 52. The spacer plate 52 can also be used in combination with the upper and / or lower end plates 45, 58 to distribute a substantially uniform load to the fuel cell assembly 24, as will be described in more detail below. .

  Preferably, the spacer plate 52 is non-conductive and can serve to electrically insulate various components of the fuel cell stack 20. Therefore, the spacer plate 52 is preferably made from a non-conductive material such as plastic. More preferably, the spacer plate 52 is made from a high performance grade engineering plastic. The high performance grade engineering plastic used to make one or more spacer plates 52 may be from upper and / or lower end plates 45, 58 to respective upper and lower ends 26 of fuel cell assembly 24. , 28 is relatively incompressible (ie, stress relaxation is negligible) under the magnitude of the compressive load applied to the fuel cell assembly 25 to transmit the compressive load to. In particular, it has been found that sulfurized polyethylene is a particularly effective material for making the spacer plate 52. Sulfurized polyethylene is a brand name of RYTON PPS, manufactured by Chevron Phillips Chemical Co., Ltd. P. And sold by Celanese AG in Frankfurt, Germany, under the Fortlon brand name. Preferably, as can be seen in FIG. 7, the spacer plate 52 has one or more apertures 84 that reduce the weight of the spacer plate 52.

  As described above, the upper and lower end plates 45, 58 are held in a fixed spaced relationship by the side plate 36 and provide a compressive load to the fuel cell assembly 24. As described above, the upper and lower end plates 45, 58 are held in a spaced apart relationship by the side plate 36. The compressive load generated at the upper and lower end plates 45, 58 of the fuel cell assembly 24 is such that the compressive load is greatest along the peripheral side wall 64 and the center of the upper and lower end plates 45, 58. In a state where the minimum value is obtained, it varies depending on the distance from the peripheral side wall 64. Because the upper and lower end plates 45, 58 are only maintained along their peripheral side walls 64, the upper and lower end plates 45, 58 are upper and lower end plates. This is because the peripheral side walls 64 of 45 and 58 cannot be further separated, but are deformed or distorted according to the compressive load applied to the fuel cell assembly 24. Since the efficiency of the fuel cell stack 20 depends in part on the uniform compressive load applied across the active region of the fuel cell assembly 24, substantially uniform compression across the entire active region of the fuel cell assembly 24. It is desirable to maintain the sexual load.

  One means for obtaining a substantially uniform load is to increase its thickness so that deflections occurring in the upper and lower end plates 45, 58 have a non-negative effect on the efficiency of the fuel cell assembly 24. This makes the upper and lower end plates 45, 58 rigid. However, providing this thickness would cause the upper and lower end plates 45, 58 to be excessively thick and add extra weight to the fuel cell stack 20, thereby providing a fuel cell stack. To reduce the efficiency per weight and volume. To avoid the need to provide relatively rigid end plates 45, 58, the stiffness of the spacer plate 52 and the stiffness of the terminal plate 56 contribute to the overall stiffness of the end assemblies 32, 34, and fuel. The end plates 45, 58 are separated from the spacer plate 52 and the terminal plate 56 so as to reduce the thickness of the end plates 45, 58 required to apply a substantially uniform compressive load across the active area of the battery assembly 24. Can be attached as an option. That is, as can be understood from FIGS. 7A to 7B, the terminal plate 56, the spacer plate 52, and the end plates 45, 58 are substantially uniform in the active region of the fuel cell assembly 24 by combining their rigidity. Can be secured together to form end assemblies 32, 34 that can distribute the compression load. As can be seen in FIG. 7A, the terminal plate 56 can be connected to the spacer plate 52 using a mechanical fastener 86, such as a threaded bolt or screw, and the combined terminal plate 56 and spacer plate. 52 can be attached to one of the end plates 45, 58 via a mechanical fastener 87. Instead, the terminal plate 56, spacer plate 52, and one end plate of the end plates 45, 58 can all be attached using an adhesive layer 88 interposed between the respective components. . As a result, the rigidity of the terminal plate 56, the rigidity of the spacer plate 52, and the rigidity of the end plates 45 and 58 are combined, and without attaching the terminal plate 56 or the spacer plate 52 to the end plates 45 and 58, Thinner end plates 45, 58 can be used to provide end assemblies 32, 34 that can apply a substantially uniform compressive load to the active region of the fuel cell assembly 24.

  As an alternative and / or as an additional example, the end plates 45, 58 and / or the spacer plate 52 can have specific shaped surfaces that compensate for the deflection of the end plates 45, 58 and are excessively thick. A substantially uniform compressive load can be distributed across the active region of the fuel cell assembly 24 without requiring the use of end plates 45, 58. That is, as can be seen in FIGS. 5A-5G, only the upper end plate 45 and the single spacer plate 52 are shown, the inner surface 46 of the upper end plate 45 is the upper end plate 45. Is dimensioned to curve away from the upper end 26 of the fuel cell assembly 24 so that the upper end plate 45 has a minimum thickness along the peripheral side wall 64 and the upper end plate. It has the maximum thickness at the center of 45. The shape of the inner surface 46 of the upper end plate 45 is such that the upper end plate 45 is spaced from the lower end plate 58 while applying a desired amount of compression load to the active region of the fuel cell assembly 24. Thus, a special contour shape is provided so as to take into account the bending that occurs in the upper end plate 45 as a result of being held along the peripheral side wall 64. 6A to 6C show a special shape as an example of the inner surface 46 of the upper end plate 45. As can be appreciated, the upper end plate 45 has a maximum thickness approximately at the center of the upper end plate 45.

  As an alternative and / or as an additional example, the spacer plate 52 can have inner and / or outer surfaces 54, 55 that are specially shaped to account for deflections that occur in the upper end plate 45. . That is, the spacer plate 52 can have a special shape such that it has a minimum thickness along the periphery of the spacer plate 52 and a maximum thickness at the center of the spacer plate 52. For example, as shown in FIG. 5G, the inner surface 54 of the spacer plate 52 can be specially shaped to extend from the spacer plate 52 toward the upper end 26 of the fuel cell assembly 24. Alternatively, as shown in FIG. 5E, the outer surface 55 of the spacer plate 52 may be positioned on the upper side so that a substantially uniform compressive load can be distributed by the end plate 45 to the active region of the fuel cell assembly 24. A special shape can be used to extend from the spacer plate 52 toward the end plate 45. As an alternative, as can be seen in FIG. 5F, both the inner surface 54 and the outer surface 55 of the spacer plate 52 are respectively the inner surface of the upper end plate 26 and the upper end plate 45 of the fuel cell assembly 24. It can be specially shaped to extend from the spacer plate 52 towards 46 so that a substantially uniform compressive load can be distributed to the active region of the fuel cell assembly 24.

  Various combinations of the formation of the inner and outer surfaces 54, 55 of the spacer plate 52 and the inner surface 46 of the upper end plate 45 are shown in FIGS. 5A-5G. The special contour shape of the surface of the upper end plate 45 and / or the spacer plate 52 not only takes into account the deflection of the upper end plate 45 but also the upper and lower ends 26, 28 of the fuel cell assembly 24. The dimensions are sized to account for deflection of the lower end plate 58 so that both receive a substantially uniform compressive load. Similarly, the inner surface 60 of the lower end plate 58 and the outer surfaces 54, 55 of the spacer plate 52 of the lower end assembly 34 are such that each component of the lower end assembly 34 is a component of the fuel cell assembly 24. It should be understood that special shapes can be formed in the same manner so as to impart a substantially uniform compressive load to the active region. Those skilled in the art will recognize that the inner surface 46 can have a variety of localized features therein to obtain a more uniform compressive load across the active region of the fuel cell assembly 24. Accordingly, the components of the upper end assembly 32 and / or the components of the lower end assembly 34 apply a substantially uniform compressive load to the active region of the fuel cell assembly 24, either individually or simultaneously. It should be understood that the surface can be formed in any shape. It should be further understood that the dimensions shown in the various drawings are exaggerated for illustrative purposes and should not be received as a fixed size for each component of the fuel cell stack 20. . That is, the deflection of the end plates 45, 58 and the modification by forming the surfaces of the end plates 45, 58 and / or the spacer plate 52 are exaggerated to better illustrate the principles of the present invention. It should be understood. The use of the terms “upper” and “lower” to describe the various components of the fuel cell stack 20 does not provide an absolute reference, but the relative relationship of the components of the fuel cell stack 20. Should be configured to provide.

  Although the fuel cell stack 20 has been described and illustrated as having a generally rectangular configuration, the shape of the fuel cell stack 20 is still within the scope of the present invention as defined by the claims, and various configurations are possible. It should be understood that For example, the fuel cell stack 20 may be columnar, in which case the fuel cell assembly 24 will be columnar along with the upper and lower end assemblies 32, 34. When the fuel cell stack 20 is columnar, the side plate 36 may be a single columnar sleeve into which the upper and lower end assemblies 32, 34 and the fuel cell assembly 24 are inserted. . The side plate 36 may be part of a columnar sleeve and may surround the components of the fuel cell stack 20. Thus, the use of the term side plate should not be limited to a flat plate, but can take a flat or curved shape, or various shapes as represented by a particular shape of the fuel cell stack 20. Should be interpreted as a plate.

  As previously described, the fuel cell stack 20 has a fuel cell assembly 24 that is maintained in a compressible load so that the fuel cell assembly 24 is more efficient. The present invention further comprises various methods of making a fuel cell stack 20 having a fuel cell assembly 24 under a compressive load. In the first method, as can be seen in FIGS. 9A-9B and FIG. 11, the fuel cell assembly 24 and / or the fuel cell stack 20 has an internal compression load of a predetermined magnitude F on the fuel cell assembly 24. Compressed by an external compression load that generates The side plates 36 maintain a fixed spaced relationship between the upper and lower end plates 45, 58 when an external compressive load is removed from the fuel cell assembly 24 and / or the fuel cell stack 20. Therefore, it is fixed to the upper and lower end plates 45 and 58. Since the upper and lower end plates 45, 58 are maintained in a fixed spaced relationship after the external compression load is removed, the internal compression load is The lower end plates 45, 58 remain dispensed to the fuel cell assembly 24.

  In the second method, that is, the predetermined compression distance method, the fuel cell assembly 24 and / or the fuel cell stack 20 is predetermined by the external compression load C, as can be understood from FIGS. 10A to 10B and FIG. The distance D is compressed. In other words, the magnitude of the external compression load is sufficient to compress the fuel cell assembly 24 by a predetermined distance D. The side plate 36 is attached to the upper and lower end plates 45, 58 (more details will be described later). Next, the external compression load is removed. The upper and lower end plates 45, 58 remain separated by their fixed spacing. The fuel cell assembly 24 remains compressed at a substantially predetermined distance D to distribute the internal compression load.

  As described above, the predetermined compression load method of making the fuel cell stack 20 having the fuel cell assembly 24 under the compression load of the predetermined size F includes the step of applying an external compression load to the fuel cell stack 20. ing. The predetermined compression load method is as follows: (1) The upper end 26 of the fuel cell assembly 24 is adjacent to the upper end plate 45, and the lower end 28 of the fuel cell assembly 24 is adjacent to the lower end plate 58. Then, the fuel cell assembly 24 is disposed between the upper and lower end plates 45, 58, and (2) the end of the fuel cell assembly 24 is compressed and receives an internal compression force of a predetermined size F. An external compressive force is applied to at least one of the part plates 45 and 58, and (3) the first and second end parts 72 and 74 of the side plate 36 are the upper and lower end plates 45 and 58, respectively. The side plate 36 is attached to the end plates 45 and 58 in a state of being attached to the end plate 45, 58, and (4) the external compression force applied to at least one of the end plates 45 and 58 is removed. And below End plate 45, 58 is to maintain a fixed spaced relationship to the interval for maintaining substantially equal compressive force to a predetermined size F according to the fuel cell assembly 25. Thus, the predetermined compression load method provides the fuel cell stack 20 having a compression force substantially equal to the predetermined magnitude F applied to the fuel cell assembly 24.

  In contrast to the above, when a predetermined compression distance method is used to assemble the fuel cell stack 20, the fuel cell stack 20 and / or the fuel cell assembly 24 are compressed with a predetermined magnitude F of compression force. Instead, it is compressed by a predetermined distance D. The reference point for the predetermined distance D can be the overall length of the fuel cell assembly 24 itself. Therefore, only the compression of the fuel cell assembly 24 by the predetermined distance D becomes a reference, and the compression of the fuel cell stack 20 is not the reference. However, it should be understood that compressing the fuel cell assembly 24 by a predetermined distance D can also be accomplished by compressing the fuel cell stack 20 by a predetermined distance D. Preferably, the predetermined distance D corresponds to applying a compressive force that causes efficient operation of the fuel cell stack 20 to the fuel cell assembly 24. The predetermined distance D for compressing the fuel cell assembly 24 can be determined in various ways. For example, the predetermined distance D can be determined by calculation from a fixed distance compression for each fuel cell 22 comprising the fuel cell assembly 24, as will be described in more detail below. It may be based on experimental data from past experience of compressing the fuel cell assembly 24 having a number. Once the predetermined distance D is determined, an external compression load is applied to the fuel cell stack 20 such that the fuel cell stack 20 and / or the fuel cell assembly 25 is compressed by the predetermined distance D. The side plate 36 is attached to the upper and lower end plates 45, 58 and the external compression load is removed. The resulting fuel cell stack 20 has a fuel cell assembly 24 that is compressed by a predetermined distance D and has an internal compression load that corresponds to efficient operation of the fuel cell stack 20.

  When the predetermined distance D is determined based on calculation (ie, based on compression of a fixed distance for each fuel processor), each fuel cell 22 is compressed by a given distance. The predetermined distance D when compressing the fuel cell assembly 24 is expressed in other words by multiplying the number n of the fuel cells 22 in the fuel cell assembly 24 by the fixed distance D to be compressed by each fuel processing device 22. For example, it is calculated by the formula D = n × d. The fixed distance at which each fuel cell 22 is compressed is selected to provide a compressive force to the fuel cell 22 having a size generally corresponding to providing efficient operation of the fuel cell assembly 24. That is, the fixed distance d to which each fuel cell 22 is to be compressed is based on the physical characteristics of the fuel cell 22 and the amount of compression required to operate the fuel cell 22 efficiently. The resulting fuel cell stack 20 has a fuel cell assembly 25 that is compressed a predetermined distance D, and has a compression load that corresponds to efficient operation of the fuel cell assembly 24.

  Based on empirical data, the predetermined distance D for compressing the fuel cell assembly 24 is not a compression of each fuel cell 22 by a fixed distance, but a past experience of compressing the fuel cell assembly 24 by a known compression load. Determined from. The resulting predetermined distance D can be the same for both methods. Because of the substantially uniform nature of the components of the fuel cell 22 that make up the fuel cell assembly 24, the number of fuel cells 22 and the compression force of the fuel cell assembly 24 of a known magnitude for each type of fuel cell 22. A general correlation can be established between the fuel cell assembly 24 and / or the compression distance of the fuel cell stack that occurs when receiving. Based on the number of fuel cells 22 constituting the fuel cell assembly 24, a predetermined distance D when the fuel cell assembly 24 is compressed in order to distribute a desired amount of compressive force to the fuel cell assembly 24 is determined. Such correlation can be used. For example, experimental data indicates that a fuel cell assembly having 5000 and 200 fuel cells, respectively, should be compressed by a distance of X and 4X, respectively, to distribute the desired amount of compression force. ing. A fuel cell stack 20 having a fuel cell assembly 24 comprised of 100 similar fuel cells 22 may be used to distribute approximately the same desired amount of compression force to the fuel cell assembly 24 based on the correlation. Should be compressed by a distance of 2X.

  Since there is some variation in the components of any given type of fuel cell 22, the resulting compressive force applied to the fuel cell assembly 24 can vary. The resulting amount of change in compressive force depends on the accuracy of the correlation and variations in the fuel cell 22. Preferably, the resulting compressive force should vary within an acceptable range around the desired magnitude so that the variation only has a negligible effect on the efficiency of the fuel cell stack 20. Thus, the experimental data method provides a fuel cell stack 20 having a fuel cell assembly 24 that is subjected to a compressive force approximately equal to a desired size. This desired compression force corresponds to efficient operation of the fuel cell assembly 24 when the fuel cell assembly 24 is compressed by a predetermined distance D.

  As described above, the spacer plate 52 can be used to provide a fuel cell stack 20 of a predetermined or uniform length L. That is, the spacer plate 52 can be used in the fuel cell stack 20 such that the fuel cell stack 20 occupies a space having a predetermined or uniform length L. The uniform length L provides a number of advantages. For example, the uniform length L allows the fuel cell stack to be easily replaced, and also allows the device where the fuel cell stack 20 is utilized because it has a standardized space for the fuel cell stack 20. To do.

  The present invention provides various assembly sequences for fuel cell stacks having a uniform length L, as shown in FIGS. 13a-13b. The desired predetermined or uniform length L of the fuel cell stack 20 can be any known length, such as an industry standard or a selected length, for example. In any case, the overall length L is a known amount. The thickness of the upper and lower end plates 45, 58, any terminal plate 56 used in the fuel cell stack 20, and any other components of the end plates 32, 34 can be measured, thus These are also known physical quantities. Based on these known quantities / dimensions, the space within the fuel cell stack 20 where the fuel cell assembly 24 is to be placed can be calculated, thus also being a known quantity. That is, the length of the space in the fuel cell stack 20 where the fuel cell assembly 24 is to be disposed is set to a predetermined or uniform length L of the fuel cell stack 20, the end plates 45 and 58, Equal to minus the dimensions of the terminal plate 56 and any other components that make up the end assemblies 32, 34. The only unknown dimension is the compressed length 30 of the fuel cell assembly 24. The compressed length 30 of the fuel cell assembly 24 depends on which method was used to make the fuel cell stack 20 and the number of fuel cells 22 that make up the fuel cell assembly 24, as described above. And can change.

  As described above, the spacer plate 52 creates a fuel cell stack 20 of a predetermined or uniform length L with the fuel cell assembly 24 being given a compressive load substantially equal to a predetermined size F. Therefore, it can be used for a predetermined compression load method. To accomplish this, either the compressed length 30 of the fuel cell assembly 24 or the compressed length of the fuel cell stack 20 ensures the required coupling thickness of one or more spacer plates 52. Need to be determined.

  The compression length 30 of the fuel cell assembly 24 is as follows: (1) The fuel cell assembly 24 is compressed with an external compression load that provides an internal compression load of a predetermined size F, as can be seen in FIG. 9A. Measuring the compressed length, or (2) such that an internal compression load of a predetermined magnitude F is applied to the fuel cell assembly 24, as can be seen in FIG. 9B. This can be determined by either compressing the fuel cell stack 20 with an external load. The compressed length 30 is determined by (A) measuring the compressed length 30 of the fuel cell assembly 24, or (B) measuring the compressed length of the fuel cell stack 20, Is the compressed length 30 of the fuel cell assembly 24 calculated by subtracting the known dimensions of the part plates 45, 58, the terminal plate 56, and any other components of the end assemblies 32, 34? It can be determined by either Once the compression length 30 of the fuel cell assembly 24 is determined, the external compression load can be removed from the fuel cell assembly 24 or the fuel cell stack 20. The compressed length 30 of the fuel cell assembly 24 is used to calculate the required bond thickness of the spacer plate 52 to make a fuel cell stack 20 of a predetermined or uniform length L. The required coupling thickness of the spacer plate 52 depends on the difference between the length of the space where the fuel cell assembly 24 is to be placed (as described above) and the compressed length 30 of the fuel cell assembly 24. equal. Accordingly, the required bond thickness of the spacer plate 52 can be calculated.

  As an alternative, the compressed length of the fuel cell stack 20 having an internal compression load of a predetermined size F can be used in the fuel cell assembly 24. The compression length of the fuel cell stack 20 is such that the fuel cell stack 20 is compressed with an external compression load so that an internal compression load having a predetermined size F is distributed to the fuel cell assembly 24. It can be determined by measuring the thickness. The external compression load on the fuel cell stack is removed. The difference between the predetermined or uniform length L of the fuel cell stack 20 and the measured compressed length of the fuel cell stack 20 is calculated. The calculated difference is the required bond thickness of the spacer plate 52.

  Once the required bond thickness of the spacer plate 52 is determined, one or more spacer plates 52 having the required bond thickness are selected. The selected spacer plate 52 is disposed between the upper and / or lower end plates 45, 58 and the respective upper and / or lower ends 26, 28 of the fuel cell assembly 24. The spacer plate 52 is compressed by applying an external compression load to the fuel cell stack 20 such that the combined thickness of the spacer plate 52 is a predetermined or uniform length L of the fuel cell stack 20. The As a result, the internal compression load of the fuel cell stack 20 having a predetermined or uniform length L should be approximately equal to a predetermined magnitude F. The side plate 36 includes upper and lower end plates 45, 58 such that the upper and lower end plates 45, 58 hold the fuel cell stack 20 in a generally predetermined or uniform length L. 58 is fixed. Finally, the external compression load is removed from the fuel cell stack 20. The resulting fuel cell stack 20 has a length that is approximately equal to a predetermined or uniform length L with the fuel cell assembly 24 compressed in a generally predetermined size F.

  The predetermined compression distance method of making the fuel cell stack 20 can also utilize the spacer plate 52 to make the fuel cell stack 20 of a predetermined or uniform length L. The required bond thickness of the spacer plate 52 includes the desired or uniform length L desired for the fuel cell stack 20, the compressed length 30 of the fuel cell assembly 24, and the end assemblies 32, 34. This is based on the thickness of the constituent parts. The compressed length 30 of the fuel cell assembly 24 is calculated by subtracting the predetermined distance D from the uncompressed length 31 of the fuel cell assembly 24. The compressed length 30 of the fuel cell assembly 24, the thickness of the end plates 45 and 58, the thickness of the terminal plate 56, and the thickness of any other components constituting the end assemblies 32 and 34 are the spacer plate. Subtracted from the predetermined or uniform length L of the fuel cell stack 20 to determine the required bond thickness of 52. The spacer plate 52 is then selected such that the combined thickness of the spacer plate 52 is approximately equal to the overall thickness required. The selected spacer plate 52 is added to the fuel cell stack 20 as described above. The resulting fuel cell stack 20 has a predetermined, predetermined or uniform length L, and the fuel cell assembly 24 is compressed by a substantially predetermined distance D, corresponding to efficient operation of the fuel cell assembly 24. An internal compression load is provided.

When the term is quantified in the text by the adverb “abbreviated”, it should be understood that the magnitude of the factor described is within an acceptable tolerance of the desired magnitude. is there.
The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are within the scope of the invention. Such changes should not be regarded as a departure from the spirit and scope of the present invention.

FIG. 1 is a perspective view of an electrochemical fuel cell stack of the present invention. FIG. 2 is a simplified cross-sectional view taken along line 2-2 of the electrochemical fuel cell stack of FIG. FIG. 3 is a partially exploded perspective view of the electrochemical fuel cell stack of FIG. 1 with a side plate attached to the electrochemical fuel cell stack. FIG. 4 is a simplified fragmentary diagram showing details of the fuel cell. 5A-5G are cross-sectional views of various configurations for the end plates and spacer plates of the electrochemical fuel cell stack of the present invention. FIG. 6A is a plan view of an inner surface having a special shape of an end plate in accordance with the principles of the present invention. 6B is a cross-sectional view taken along line BB of the end plate of FIG. 6A. 6C is a cross-sectional view taken along line CC of the end plate of FIG. 6A. 7A-7B are partial cross-sectional views of the end assembly showing various methods of attaching the end assembly components of the electrochemical fuel cell stack of the present invention. FIG. 8 is a perspective view of a spacer plate used in the electrochemical fuel cell stack of the present invention in which holes are used to reduce the weight of the spacer plate. 9A to 9B are simplified cross-sectional views of an electrochemical fuel cell stack showing the steps of compressing the fuel cell assembly and the fuel cell stack, respectively, with a predetermined magnitude F of compressive force. 10A through 10B are simplified cross-sectional views of an electrochemical fuel cell stack showing the steps of compressing the fuel cell assembly and the fuel cell stack, respectively, at a predetermined distance D. FIG. 11 is a flowchart showing the steps of a compression method with a predetermined force for making a fuel cell stack in accordance with the principles of the present invention. FIG. 12 is a flowchart showing the steps of a predetermined compression distance method for making a fuel cell stack in accordance with the principles of the present invention. FIG. 13 is a flowchart showing the steps of using a spacer plate to make a fuel cell stack of a predetermined or uniform length. FIG. 13 is a flowchart showing the steps of using a spacer plate to make a fuel cell stack of a predetermined or uniform length.

Claims (21)

An electrochemical fuel cell stack,
A plurality of fuel cells arranged in a stacked configuration to form a fuel cell assembly, the fuel cell assembly having first and second ends, with a length between the ends. Defining the plurality of fuel cells;
First and second end plates respectively disposed at the first and second end portions of the fuel cell assembly;
At least one side plate having first and second end portions attached to the first and second end plates, respectively, the at least one side plate comprising the first and second end plates; The at least one side plate holding the first and second end plates in a spaced relationship such that two end plates distribute compressive force to the fuel cell assembly;
An electrochemical fuel cell stack comprising:   The first and second end portions of the at least one side plate have a predetermined amount of the compressive force applied to the fuel cell assembly by the first and second end plates. The fuel cell stack according to claim 1, wherein the fuel cell stack is attached to the first and second end plates respectively.   The first and second end portions of the at least one side plate are respectively attached to the first and second end plates such that the length of the fuel cell assembly is compressed by a predetermined distance. The fuel cell stack according to claim 1.   The first and second end portions of the at least one side plate are on peripheral sidewalls of each of the first and second end plates extending substantially parallel to the length direction of the fuel cell assembly. The fuel cell stack of claim 1, each attached.   The fuel cell stack of claim 4, further comprising a pair of side plates attached to the peripheral side wall of each of the end plates.   The first and second ends of the at least one side plate have at least one opening, and the first and second ends of the at least one side plate are connected to the first and second ends. The fuel cell stack of claim 4, wherein a mechanical fastener is inserted through the opening for attachment to each second end plate.   The fuel cell stack according to claim 6, wherein the at least one opening formed in at least one of the first end or the second end is a slot.   A first mechanical fastener that attaches the first end of the at least one side plate to the first end plate engages a threaded opening in the first end plate. A second mechanical fastener having a thread forming portion and attaching the second end of the at least one side plate to the second end plate is a screw in the second end plate The fuel cell stack according to claim 6, further comprising a thread forming portion that engages with the forming opening.   The at least one opening formed in at least one of the first and second ends of the at least one side plate is one of a plurality of openings, and the plurality of openings 7. The fuel cell stack of claim 6, wherein the fuel cell stack is spaced around the at least one of the first and second ends of the at least one side plate. An electrochemical fuel cell stack,
A plurality of fuel cells arranged in a stacked configuration to form a fuel cell assembly, the fuel cell assembly having first and second ends, with a length between the ends. Defining the plurality of fuel cells;
First and second end plates disposed at the first and second ends of the fuel cell assembly, respectively, for applying a compressive force to the fuel cell assembly;
At least one side plate having first and second end portions attached to the first and second end plates, respectively, the at least one side plate comprising the first and second end plates; The at least one side plate covering a portion of the fuel cell assembly between two end plates and providing a protective covering for the fuel cell assembly;
An electrochemical fuel cell stack comprising:   The first and second end portions of the at least one side plate are a portion of the first and second end portions of the at least one side plate, and the first and second end plates are The first and second end plates are respectively attached to the first and second end plates in such a manner that the first and second end plates are held in a spaced relationship so that the compression force is applied to the fuel cell assembly. The fuel cell stack according to claim 10, wherein   11. The at least one side plate has an opening formed therein to allow a terminal formed on a terminal end plate to pass through the at least one side plate. The fuel cell stack described.   The fuel cell stack of claim 10, wherein the at least one side plate is made of metal.   The fuel cell stack of claim 10, wherein the at least one side plate provides a shield against electromagnetic interference to the fuel cell assembly.   The fuel cell stack of claim 14, wherein the at least one side plate is electrically grounded.   A plurality of side plates, wherein each side plate of the plurality of side plates has the entire fuel cell assembly confined by the plurality of side plates between the first and second end plates; The fuel cell stack of claim 10, wherein the fuel cell stack covers a portion of the fuel cell assembly between the first and second end plates. A method of making an electrochemical fuel cell stack,
With the first end of the fuel cell assembly adjacent to the first end plate and the second end of the fuel cell assembly adjacent to the second end plate, the fuel cell assembly is Disposed between the first and second end plates;
Applying an external compressive force to at least one of the end plates so that the fuel cell assembly is compressed;
So that when the external compressive force is removed, the first and second end plates maintain a fixed spaced relationship and the fuel cell assembly remains compressed. At least one side plate is attached to the end plate in a manner that first and second ends of at least one side plate are attached to the first and second end plates;
Removing the external compressive force from the end plate, comprising each step. Applying the external compressive force comprises applying a predetermined amount of compressive force so that the fuel cell assembly receives the predetermined amount of compressive force;
The step of attaching the at least one side plate to the end plate maintains a spaced relationship between the first and second end plates when the external compressive force is removed. The first and second end plates of the at least one side plate are connected to the first and second end plates so as to maintain the predetermined amount of the compressive force applied to the fuel cell assembly. The method according to claim 17, further comprising the step of attaching to each. Applying the external compressive force comprises applying a compressive force to the end plate such that the fuel cell assembly is compressed a predetermined distance in the direction of the external compressive load;
Attaching the at least one side plate to the end plate maintains a spaced relationship between the first and second end plates when the external compressive force is removed; In addition, the first and second end portions of the at least one side plate are used as the first and second end plates so that the fuel cell assembly maintains the compressed state for the predetermined distance. The method of claim 17, comprising each attaching step.   The method of claim 17, wherein the step of attaching the at least one side plate to the end plate comprises attaching a pair of side plates to the surrounding sidewall of each of the end plates.   The at least one side plate has a fixed length between the first and second end plates such that the at least one side plate provides a protective covering for the fuel cell assembly. The method of claim 17, wherein the fuel cell assembly is confined.

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