JP2007213921A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a fuel cell prevented from erosion of a collector plate, having improved sealing performance and power generating performance. <P>SOLUTION: A laminated body 6 is constituted by serially laminating as many cells 60 as are needed for a given output scale, in which, a first through-hole 41 is provided in a lamination direction of the laminated body 6, a second through-hole 42 of the collector plate 2 and a third through-hole 43 of an insulating plate 3 are communicated with the first through-hole 41, and fluid such as fuel gas, oxidant gas, or a coolant is circulated by the first to third though-holes in a lamination direction of the laminated body 6. An opening of the second through-hole 42 is made larger than that of the first through-hole 41 and the third through-hole 43, so that it surrounds the openings of the first through-holes 41 and the third through-holes 43. Further, a sealing member 5 is provided inside the second through-hole 42 pressure-contacted with the laminated body 6 and the insulating plate 3, in order to isolate the collector plate 2 from the fluid and seal off the fluid from leaking. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel cell, and more particularly to a structure around a current collector plate.

A current collector plate (current collector plate), an insulating plate (insulating plate), and a flange plate (pressurized end plate) are sequentially arranged at both ends in the stacking direction of the fuel cell body (stacked body) in which a plurality of cells and separators are alternately stacked. Gaskets are provided in the outward direction, between the battery body and the current collecting plate, between the current collecting plate and the insulating plate, and between the insulating plate and the flange plate. In addition, a polymer material lining is applied in the vicinity of the peripheral edge, and the fuel cell main body, current collecting plate, insulating plate and flange plate are laminated and fixed with bolts, etc., between the battery main body, current collecting plate, insulating plate and flange plate There is one that improves the corrosion resistance of the opening part of the current collector plate and flange plate as well as improving the adhesion of If example see Patent Document 1).
In addition, a fluid passage (through hole) is formed in the stacking direction of a laminated body in which a plurality of cells each having an electrode unit sandwiched by separators are stacked, and an insulation having a supply / discharge passage (through hole) for supplying and discharging fluid to and from the fluid passage. The current collecting member is sandwiched between the conductive supply / discharge member and the laminate, and a seal member is disposed between the fluid passage and the supply / discharge passage and the current collecting plate. The size of the current collecting member is the size of the electrode of the electrode unit. In some cases, the current collector plate is sealed from the fluid by the seal member provided inside the seal member (see, for example, Patent Document 2).

JP 2002-298899 A (first page) Japanese Patent No. 3714093 (first page)

In the device disclosed in Patent Document 1, since the current collector plate is sandwiched across the entire surface of the fuel cell body, a surface pressure is applied to the entire cell surface during fixing. However, since the fluid supply opening and the discharge opening penetrate the current collector plate, even if the opening portion of the current collector plate is covered with a corrosion-resistant material such as a polymer material lining, the covering material is reducible. There has been a problem that it is difficult to guarantee long-term durability because it is exposed to highly corrosive fluids such as hydrogen gas, oxidizing air, and a cooling medium.
The one shown in Patent Document 2 is a structure in which the current collector plate is kept to the size of the electrode surface and does not extend to the fluid passage or the supply / discharge passage, so that it does not touch the fluid. The tightening force in the stacking direction is applied mainly to the electrode surface corresponding to the size of the current collector plate, the surface pressure is biased around the fluid passage and the supply / exhaust passage, and the applied surface pressure is weakened. There was a problem that it was difficult to prevent the fluid in the passage and the supply / discharge passage from leaking.

  The present invention has been made to solve such a problem, and an object of the present invention is to obtain a fuel cell in which corrosion of a current collector plate is prevented and power generation performance is improved.

  The fuel cell according to the present invention includes a laminate in which a plurality of cells each having an electrode unit sandwiched between separators, a current collector plate disposed at both ends of the laminate, and an outer side of the current collector plate. In the fuel cell in which the provided insulating plate is tightly fixed, the stacked body has a first through hole in the stacking direction, and the current collector plate has a second through hole communicated with the first through hole. The insulating plate has a third through-hole communicating with the second through-hole, and the opening of the second through-hole has an opening of the first through-hole and the first through-hole. 3 is larger than the opening of the three through holes, surrounds the opening of the first through hole and the opening of the third through hole, and is provided in the second through hole. And a sealing member that surrounds the opening of the third through-hole and the opening of the third through hole and is press-contacted by the laminated body and the insulating plate. It is.

  The seal member can prevent the current collector plate from being corroded by a fluid such as fuel gas, oxidant gas or coolant. In addition, since it is not necessary to limit the size of the current collector plate, surface pressure is applied in the cell surface and the stacking direction of the stacked body, thereby improving the sealing performance and improving the power generation performance of the fuel cell.

Embodiment 1 FIG.
FIG. 1 is a side view showing a schematic configuration of a fuel cell according to Embodiment 1 of the present invention. FIG. 2 is a cut-out view of the lower end of the fuel cell in FIG. FIG. 3 is a longitudinal sectional view showing a schematic configuration of a lower end portion of the fuel cell of FIG.
As shown in FIGS. 1 to 3, the fuel cell according to the present embodiment forms a stack 6 by stacking cells 60 in series in a number necessary for a predetermined output scale. In the case of a solid polymer electrolyte fuel cell, an electrode unit 62 having an electrolyte sandwiched between electrodes (a fuel electrode and an oxidant electrode) is sandwiched by a separator 61 having a flow path for fuel gas, oxidant gas or coolant. Uses a solid polymer electrolyte membrane as the electrolyte.
Each flow path of each separator 61 communicates with each other, and a first through hole 41 is formed in the stacking direction of the stacked body 6. The first through hole 41 of the laminate 6, the second through hole 42 of the current collector 2, and the third through hole 43 of the insulating plate 3 communicate with each other to form the first to third through holes. A fluid such as a fuel gas, an oxidant gas, or a coolant is passed through the holes in the stacking direction (indicated by arrows in the drawing) of the stacked body 6.
The output of the fuel cell is taken out from current collector plates 2 provided at both ends of the laminate 6. An insulating plate 3 is laminated on the outside of the current collector plate 2, and a pressure end plate 14 is laminated on the outside of the insulating plate 3, and the surface pressure from both ends of the laminated body 6 is applied to each cell by the pressure rod 15 and the pressure nut 16. Applied to 60 and fixed. Although the pressurization mechanism is a general one, the structure in which the surface pressure is applied to the laminate 6 is the same in any pressurization structure.

In particular, in the fuel cell of the present embodiment, as shown in FIGS. 2 and 3, the first through hole 41 of the laminated body 6, the second through hole 42 of the current collector plate 2, and the insulating plate 3. In the third through hole 43, the opening of the second through hole 42 is larger than the openings of the first through hole 41 and the third through hole 43, and the projection surface of the opening of the second through hole 42. The opening of the second through hole 42 is the opening of the first through hole 41 so that the projection surface of the opening of the first through hole 41 and the opening of the third through hole 43 is included therein. And it is comprised so that the opening part of the 3rd through-hole 43 may be surrounded. The insulating plate 3 has an annular convex portion 31 along the outer periphery of the opening. The outer periphery of the annular convex portion 31 is smaller than the opening of the second through hole 42 and is within the opening of the second through hole 42. It is a size that fits.
A seal member 5 is provided in the second through hole 42 so as to surround the opening of the first through hole 41 and the opening of the third through hole 43, and the seal member 5 is insulated from the laminate 6. The plate 3 is in pressure contact with the annular convex portion 31. In addition, a groove 11 that stably holds the seal member 5 is formed on the end face of the laminated body 6 facing the annular protrusion 31, that is, the separator 61 of the terminal cell 60 of the laminated body 6. By providing the groove 11 on the side of the strong separator, it is possible to make the insulating plate 3 side weak in strength flat, so that deterioration of the insulating plate and generation of cracks due to prolonged application of surface pressure. Can be prevented.

As shown in FIG. 3, the height (h ₁ ) of the annular convex portion 31 of the insulating plate 3 is smaller than the thickness (h ₂ ) of the current collector plate, so that the surface pressure received from the upper and lower sides during fixing is the current collector plate 2. In the laminated body 6, the surface pressure is applied to the region indicated by the laminated cell pressure receiving portion 9. In addition, since the annular convex portion 31 of the insulating plate 3 is not in contact with the separator 61 with a gap therebetween, no surface pressure is applied to the region indicated by the laminated cell non-pressure receiving portion 8 in the laminated body 6. The member 5 isolates the current collector plate 2 from the fluid and is pressed against the annular convex portion 31 of the insulating plate 3 and the separator 61, so that leakage of fluid flowing in the laminating direction is sealed. The plate 2 is prevented from coming into contact with the fluid. Therefore, since the low-cost metal excellent in conductivity can be used as the current collector plate 2, the cost can be reduced.
In addition, since the current collector plate 2 according to the present embodiment is configured as described above, the outer shape can be made substantially the same as the end face of the stacked body 8, and the entire surface of the cell 60 of the stacked body 6 and the stacking direction. The surface pressure can be applied substantially uniformly to the entire surface, sufficient surface pressure is also applied to the sealing member inside the cell 60, the fluid is satisfactorily sealed over the entire laminate, and high-performance power generation performance is obtained.

Generally, the metal rolled plate material used for the current collector plate 2 and the insulating material used for the insulating plate 3 are materials having a relatively large variation in the thickness direction (for example, aluminum 2017 (JIS H4000) has a thickness of 16 to In the case of 22 mm, the variation is defined as 0.8 mm or less. }, And when it is cut and used at a low cost, it is the limit to suppress the surface roughness to about ± 0.05 mm. In molding, the surface roughness should be suppressed to ± 0.05 mm or less. (The 10th Fuel Cell Symposium Preliminary Proceedings, Published by Fuel Cell Development Information Center, 2003, p.102).
Therefore, when the height (h ₁ ) of the annular protrusion 31 of the insulating plate 3 and the thickness (h ₂ ) of the current collector plate 2 are designed to be h ₂ −h ₁ > 0.05 mm, the thickness of the seal member 5 is designed. It is desirable that the height be 0.15 mm or more higher than the depth of the groove on the separator 61 side before lamination. In this case, when a member is laminated or a surface pressure is applied by fixing, an average compression of 0.1 mm and a minimum of 0.05 mm are sufficient. The amount of compression varies depending on the groove depth, and in the case of an O-ring for general equipment (JIS B 2401), it is compressed by about 8 to 30%. Therefore, the amount of compression and the thickness (h ₂ ) of the current collector plate are insulated from each other. Based on the height (h ₁ ) of the annular convex portion of the plate 3, the thickness of the seal member 5 and the depth of the groove 11 are determined.

In the present embodiment, the case where the annular projection 31 is provided on the insulating plate 3 is shown. However, the annular projection 31 may be provided on the separator 61, and the annular projection 31 is provided on both the separator 61 and the insulating plate 3. May be provided.
FIG. 4 is a longitudinal sectional view showing a schematic configuration of the lower end portion of another fuel cell in the present embodiment, but without providing the annular protrusion 31 on the insulating plate 3 as shown in FIG. The seal member 5 having a thickness corresponding to the height of the three annular protrusions 31 is used alone, and the same effect as that shown in FIG. 3 can be obtained.

Embodiment 2. FIG.
FIG. 5 is a longitudinal sectional view showing an outline of the fuel cell end portion in the second embodiment of the present invention.
In the present embodiment, in the fuel cell having the same configuration as in the first embodiment, a sheet-like elastic member 13 having the same size as the current collector plate 2 is sandwiched between the separator 61 and the current collector plate 2. It is what has been. Here, the elastic member 13 is electrically conductive because it is provided between the separator 61 and the current collector plate 2, and the total (h ₃ ) of the thickness of the elastic member 13 and the current collector plate 2 (h ₂ ) is insulated. The relationship of the height (h ₁ ) of the annular convex portion 31 of the plate 3 is provided so that h ₃ −h ₁ > 0. The thickness of the elastic member 13 at this time is an average thickness after the surface pressure is applied.
Since the current collector plate 2 made of metal, the insulating plate 3 formed of an insulating material such as resin, etc. are rigid bodies, high-precision processing such as surface grinding is required to make uniform surface contact during lamination. Become. Therefore, generally, the surface is subjected to an inexpensive cutting or molding method, but in this case, the surface roughness is generally ± 0.05 mm. Such contact due to the surface roughness occurs, and the applied surface pressure becomes uneven. Contact at the contact surface between the separator 61 and the current collector plate 2 leads to an increase in contact resistance, and battery characteristics are reduced. A drop will occur.
On the other hand, in the present embodiment, in addition to the effects of the first embodiment by providing the elastic member 13, the elastic member 13 absorbs the surface roughness of the current collector plate 2 and the separator 61 to become a cushioning material, Since good contact is obtained, the effect of reducing the electrical resistance and reducing the bias of the applied surface pressure is obtained.
For example, in order to finely adjust the thickness so that h ₃ −h ₁ > 0.05 mm, the elastic member 13 is carbon paper {trade name: TGP-H-090, manufactured by Toray Industries, Inc.}, { It is desirable to use a product name: TGP-H-060, manufactured by Toray Industries, Inc.}). The carbon paper is conductive, absorbs local irregularities due to elasticity and becomes a cushioning material, and hardly undergoes creep over time.

The elastic member 13 may be inserted between the insulating plate 3 and the current collector plate 2, and in this case, it may not be conductive. As the elastic member 13 inserted between the insulating plate 3 and the current collector plate 2, a relatively flexible material such as a resin sheet made of polytetrafluoroethylene or ethylene-propylene copolymer is used. It is possible to easily eliminate the contact by reducing the unevenness of the current collector plate 2 and finely adjust the thickness as described above.
The elastic member 13 may be sandwiched between the current collector plate 2 and the separator 61 and between the insulating plate 3 and the current collector plate 2.

1 is a side view showing a schematic configuration of a fuel cell in Embodiment 1 of the present invention. FIG. 2 is a perspective view clearly showing the stacked state of each member at the lower end of the fuel cell in FIG. 1. It is a longitudinal cross-sectional view which shows schematic structure of the lower end part of the fuel cell of FIG. FIG. 5 is a longitudinal sectional view showing a schematic configuration of a lower end portion of another fuel cell in the first embodiment. It is a longitudinal cross-sectional view which shows the outline of the fuel cell edge part in Embodiment 2 of this invention.

Explanation of symbols

2 current collector plate, 3 insulating plate, 31 annular convex portion, 41 first through hole, 42 second through hole, 43 third through hole, 5 seal member, 6 laminate, 60 cells, 61 separator, 62 Electrode unit, 11 groove, 13 elastic member.

Claims (6)

A laminated body in which a plurality of cells each having an electrode unit sandwiched between separators are laminated, a current collector plate disposed at both ends of the multilayer body, and an insulating plate disposed outside the current collector plate In the fixed fuel cell, the stacked body has a first through hole in the stacking direction, the current collector has a second through hole communicating with the first through hole, and the insulating plate Has a third through-hole communicating with the second through-hole, and the opening of the second through-hole is formed from the opening of the first through-hole and the opening of the third through-hole. Largely surrounding the opening of the first through-hole and the opening of the third through-hole and provided in the second through-hole, the opening of the first through-hole and the third through-hole A fuel cell comprising a seal member surrounding an opening of a hole and press-contacted by the laminate and the insulating plate. The fuel cell according to claim 1, wherein the current collector plate has substantially the same size as the end face of the laminate. The fuel cell according to claim 1 or 2, wherein a groove for holding the seal member is provided in at least one of the laminate and the insulating plate. 4. The elastic member is sandwiched between at least one of the current collector plate and the laminated body and between the current collector plate and the insulating plate. 5. Fuel cell. The laminated body has an annular convex portion surrounding the opening portion of the first through hole on the end surface, or the insulating plate has an annular convex portion surrounding the opening portion of the third through hole, and the sealing member is the annular convex portion. The fuel cell according to any one of claims 1 to 3, wherein a height of the annular convex portion is smaller than a thickness of the current collector plate. The laminated body has an annular convex portion surrounding the opening portion of the first through hole on the end surface, or the insulating plate has an annular convex portion surrounding the opening portion of the third through hole, and the sealing member is the annular convex portion. The fuel cell according to claim 4, wherein a height of the annular convex portion is smaller than a sum of a thickness of the current collector plate and a thickness of the elastic member.

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