JP2018181422A - Terminal plate for fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a terminal plate for fuel cell capable of restraining warpage of a plate body bonded to a collector terminal for outputting generated power.SOLUTION: A terminal plate 4 for fuel cell includes a collector terminal 41 composed of a first metal, and outputting the collected power, and a tabular plate body 40 composed of a second metal having a linear coefficient of expansion smaller than that of the first metal, and a corrosion resistance larger than that of the first metal, and laminated to face the cell. Outer peripheral surface 40a of the plate body 40 and the end face 41a of the terminal 41 on the plate body side are confronted and welded.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a terminal plate for a fuel cell.

  The fuel cell has a stack structure in which a plurality of fuel cells, which are power generation units, are stacked, and includes a terminal plate for extracting generated power to the outside. The terminal plate is attached to both ends of the fuel cell stack, and includes a current collection terminal for current collection protruding from the outer periphery of the plate. The current collection terminals of the terminal plate are used to output the generated power obtained in each fuel cell to the outside. Such a terminal plate is in contact with the generated water and the cooling water after receiving the potential associated with the power generation of the fuel cell unit, and therefore it is necessary to secure the sealability while securing the corrosion resistance.

  It is known to apply a highly corrosion resistant titanium plate as a terminal plate for a fuel cell in order to ensure corrosion resistance. For example, the terminal plate described in Patent Document 1 below has a configuration in which a core plate having a current collection terminal made of aluminum is sandwiched by a highly corrosion-resistant titanium plate (hereinafter also referred to as a plate main body) to ensure conductivity. doing.

JP, 2015-088294, A

  By the way, when producing a terminal plate, as shown in FIG. 3, the method to overlap and weld the current collection terminal 91 which consists of aluminum, and the plate main body 92 which consists of titanium (code | symbol W shown to FIG. 3 (B)) There is a joint). However, since the linear expansion coefficient of aluminum is larger than the linear expansion coefficient of titanium, a difference in expansion or contraction due to heat at the time of welding occurs, and there is a risk that warpage may occur in titanium having a smaller amount of expansion or contraction compared to aluminum. The

  Then, an object of this invention is to provide the terminal plate for fuel cells which can suppress the curvature of the plate main body joined to the current collection terminal for outputting generated electric power outside.

  The terminal plate for a fuel cell according to the present invention is a terminal plate for a fuel cell which is disposed at the end in the stacking direction of a cell stack in which a plurality of cells are stacked and is used for collecting the generated power of the fuel cell And a terminal portion for outputting the collected power to the outside, and a second metal having a smaller linear expansion coefficient and a higher corrosion resistance than the first metal, And the plate-like plate main body to be stacked, and the outer peripheral surface of the plate main body and the end face on the plate main body side of the terminal portion are butted to be welded.

  According to this configuration, since the end face on the plate main body side of the terminal portion and the outer peripheral surface of the plate main body are butted against each other and welded, a metal material whose linear expansion coefficient of the terminal portion is larger than the linear expansion coefficient of the plate main body Even if it is configured, it is possible to suppress that the plate body is pulled to the terminal portion by heat contraction and the plate body is warped in the plane upward direction (in other words, the plate thickness direction).

  According to the present invention, it is possible to provide a terminal plate for a fuel cell capable of suppressing the warpage of the plate main body joined to the current collection terminal for outputting the generated power to the outside.

It is an explanatory view showing a schematic structure of a fuel cell stack. It is explanatory drawing which expands and shows the principal part of the terminal plate shown in FIG. It is explanatory drawing which expands and shows the principal part of the conventional terminal plate.

  Hereinafter, embodiments of the present invention will be described with reference to the attached drawings. The following description of the preferred embodiments is merely an example, and is not intended to limit the present invention, its applications, or its applications.

  First, the configuration of a fuel cell provided with a terminal plate in the present embodiment will be described. FIG. 1A is a schematic perspective view showing a schematic configuration of a fuel cell, and FIG. 1B is a cross-sectional view showing a principal part of the fuel cell. The members constituting the fuel cell shown in FIG. 1 are shown as an example, and the fuel cell in the present embodiment is not limited to the configuration or shape shown in FIG. 1 and will be described below. A configuration other than the configuration can be included.

  As shown in FIG. 1, a solid polymer fuel cell 1 includes a stack main body 3 (also referred to as a cell stack) in which a large number of unit cells 2 as basic units are stacked. The fuel cell 1 is constructed by sequentially laminating a terminal plate 4 (see FIG. 1 (B)), an insulator (insulation plate) 5 and an end plate 6 on the outside of the unit cell 2 located at both ends of the stack body 3. ing. In FIG. 1, the configuration of one end of the stack body 3 is illustrated, and the configuration of the other end is omitted.

  Although not shown, the fuel cell 1 is fixed by fastening a tension plate provided so as to bridge the two end plates 6 to each end plate 6 with a bolt, whereby in the cell stacking direction It will be in the state where predetermined compression power was applied. Although not shown, the unit cell 2 is an electrolyte membrane made of an ion exchange membrane, a MEA (Membrane Electrode Assembly) made of a pair of electrodes sandwiching the electrolyte membrane from both sides, and a pair of separators which sandwich the MEA from the outside. It consists of Each separator is formed of carbon or metal as a base material and has conductivity. Each separator has a fluid flow path for supplying an oxidizing gas (oxygen gas, usually air) or a fuel gas (hydrogen gas) to each electrode. Such a configuration causes an electrochemical reaction in the MEA of the single cell 2 to obtain an electromotive force.

  In the fuel cell 1, a fuel gas manifold 20, an oxidizing gas manifold 20, and a refrigerant manifold 20 are formed penetrating in the cell stacking direction (in practice, they are separate but denoted by the same reference numerals) Is omitted.). The manifolds 20 for the respective fluid flow paths are formed in the fuel cell 1 by penetrating the end plate 6, the insulator 5, the terminal plate 4, and the separators of the single cells 2 in the cell stacking direction. Each fluid (fuel gas, oxidizing gas, refrigerant) is supplied from each fluid pipe (not shown) provided on the end plate 6 at one end of the fuel cell 1 to each manifold 20 a on the inlet side, and formed in each separator Flow through the fluid flow path. Finally, each fluid is discharged from each manifold 20b on the outlet side to each fluid piping provided on the end plate 6.

  The terminal plate 4 includes an output terminal 41 and is provided between (the separator of) the unit cell 2 at the outermost position of the stack 3 and the insulator 5. The terminal plate 4 can be formed of various metals. The electricity generated in each single cell 2 of the fuel cell 1 is collected on the terminal plate 4 and taken out by the output terminal 41.

  Subsequently, a method of bonding the output terminal 41 and the plate main body 40 in the terminal plate 4 will be described. 2 (A) is a schematic perspective view showing the periphery of the output terminal 41 in the terminal plate 4 in an enlarged manner, and FIG. 2 (B) is a view of FIG. 2 (A) from the arrow A direction. As a comparative example, an explanatory view showing a method of joining the output terminal and the plate main body in the conventional terminal plate is shown in FIG. FIG. 3A is a schematic perspective view showing the periphery of the output terminal in the conventional terminal plate in an enlarged manner, and FIG. 3B is a view of FIG.

  First, a method of bonding the conventional terminal plate 90 will be described. As shown in FIG. 3, in the conventional terminal plate 90, a plate-like plate body 92 in surface contact with the cells and a plate body 92 provided so as to protrude from the periphery of the plate body 92 are used to output the collected power to the outside. The welding is performed in a state in which the output terminal 91 of the above is overlapped in the thickness direction (the left and right direction in FIG. 3B). When the output terminal 91 is made of aluminum to ensure conductivity, and the plate body 92 is made of titanium having high corrosion resistance, the linear expansion coefficient of aluminum is three times the linear expansion coefficient of titanium. The amount of extension due to the heat generation of When the welding process is completed and the temperature drops, the amount of shrinkage of the aluminum is larger than that of the titanium, so the titanium is pulled by the aluminum and the warpage in the plane upward direction (right direction in FIG. 3B) is titanium. Occurs on Since the terminal plate 90 is disposed at the end of the cell stack in which a plurality of unit cells 2 (see FIG. 1) are stacked, the terminal plate 90 has a warp in the plane upward direction (in other words, the cell stacking direction). If it occurs, there arises a problem that the sealability is reduced.

  On the other hand, the output terminal 41 and the plate main body 40 in the terminal plate 4 of the present embodiment are joined as follows. Specifically, a plate-like plate main body 40 disposed at an end of the cell stack in a state of surface contact with the cells, and an outer surface 40 a of the plate main body 40 are provided so as to protrude and collect collected power In the terminal plate 4 including the output terminal 41 for outputting the signal to the outside, the end surface 41a of the output terminal 41 on the plate main body side and the outer peripheral surface 40a of the plate main body 40 (the end surface on the output terminal side of the plate main body 40) They are butted and welded. The output terminal 41 is made of, for example, aluminum, and the plate main body 40 is made of, for example, titanium. In this manner, by welding the end faces (the end face 41a and the end face 40a) to butt, warpage in the plane upward direction of the plate body 40 is suppressed, and the plate body 40 in the plane horizontal direction (in other words, the plane direction, FIG. In the case of), warping in the vertical direction may occur. Such warping of the plate main body 40 in the horizontal direction in the plane does not deteriorate the sealing performance when the terminal plate 4 is laminated together with the single cells 2 (see FIG. 1) and used as a stack structure. Therefore, the sealing performance can be improved as compared with the configuration in which the conventional terminal plate shown in FIG. 3 is used for a fuel cell.

  The flexural rigidity of the terminal plate produced by the joining method described with reference to FIGS. 2 and 3 was measured. As measured, the bending rigidity (EI1) of the terminal plate 4 (see FIG. 2) in which the end faces are butt-welded is about 300,000 of the bending rigidity (EI2) of the terminal plate 90 (see FIG. 3) overlapped and welded. It was verified that the amount was doubled (EI1 / EI2 ≒ 300000), and it was confirmed that the amount of warpage itself could be reduced.

  In addition, the plate main body 40 of the terminal plate 4 shown in FIG. 2 should just be a structure containing a material with high corrosion resistance, for example, applying Ti, SUS, etc. is mentioned. Moreover, the output terminal 41 of the terminal plate 4 should just contain the material which ensures electroconductivity, for example, applying Cu, Al is mentioned. Further, the shapes and sizes of the terminal plate 4, the plate main body 40 and the output terminal 41 are not limited to the illustrated example, and may be changed to various shapes and sizes as long as the functions of the respective members are provided. It is possible.

  In the embodiment described above, the method of joining the plate main body 40 and the output terminal 41 is not particularly limited, and examples thereof include welding and friction stir welding (FSW).

  According to the embodiment described above, since the end face on the plate body side of the terminal portion and the end face on the terminal portion side of the plate body are butted and welded, the linear expansion coefficient of the terminal portion is the linear expansion of the plate body Even if the plate is made of a metal material having a coefficient larger than the coefficient, it is possible to suppress the plate body from being pulled in the terminal portion by heat contraction and warping the plate body in the plane upward direction (in other words, the plate thickness direction). As a result, it is possible to suppress the occurrence of bending in the terminal plate at the time of cell lamination, and it is possible to prevent the sealing performance from being deteriorated due to the bending and leading to the leak of gas or the like.

  The embodiments described above are for the purpose of facilitating the understanding of the present invention, and are not for the purpose of limiting the present invention. The elements included in the embodiment and the arrangement, the material, the conditions, the shape, the size, and the like of the elements are not limited to those illustrated, and can be changed as appropriate. In addition, configurations shown in different embodiments can be partially substituted or combined with each other.

1 ... fuel cell 2 ... single cell 3 ... stack body (cell stack)
DESCRIPTION OF SYMBOLS 4 ... Terminal plate 5 ... Insulator 6 ... End plate 20 ... Manifold 40 ... Plate main body 41 ... Output terminal (terminal part)

Claims (1)

A terminal plate for a fuel cell, which is disposed at an end in the stacking direction of a cell stack in which a plurality of cells are stacked, and used for collecting power generated by the fuel cell,
A terminal portion made of a first metal and outputting the collected power to the outside;
And a plate-like plate main body which is made of a second metal having a smaller linear expansion coefficient and a higher corrosion resistance than the first metal, and which is laminated to face the cell.
A terminal plate in which an outer peripheral surface of the plate main body and an end face of the terminal portion on the plate main body side are butted to be welded.