JP2016157601A - Fuel cell stack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress damage on a resin frame member, composing an end cell unit, as much as possible by simple configuration.SOLUTION: A fuel cell stack 10 includes a power generation cell 12, where an electrolyte film membrane/electrode structure 28 with resin frame is sandwiched by a first separator 30 and a second separator 32. At opposite ends of a laminate 14 in the lamination direction, end cell units 12A, 12B are disposed. A resin frame member 56A composing the end cell units 12A has a contact surface 58a, in contact with the outermost first separator 30disposed on the terminal plate 16a side, and a relief groove 60a is provided in the contact surface 58a.SELECTED DRAWING: Figure 3

Description

  The present invention includes a power generation cell having an electrode / electrode structure with a resin frame in which electrodes are disposed on both sides of the electrolyte membrane, and a resin frame member is provided around the outer periphery of the electrolyte membrane, and a separator. The present invention relates to a fuel cell stack provided with a stacked body in which a plurality of the power generation cells are stacked.

  For example, in a polymer electrolyte fuel cell, an electrolyte membrane / electrode structure in which an anode electrode is disposed on one side of an electrolyte membrane made of a polymer ion exchange membrane and a cathode electrode is disposed on the other surface side ( MEA). The electrolyte membrane / electrode structure constitutes a power generation cell by being sandwiched between separators (bipolar plates). A fuel cell is usually incorporated in a fuel cell vehicle (fuel cell electric vehicle or the like) as a vehicle fuel cell stack, for example, by stacking a predetermined number of power generation cells.

  In the electrolyte membrane / electrode structure, one electrode is set to an outer dimension smaller than that of the solid polymer electrolyte membrane, and the other electrode is set to the same outer dimension as the solid polymer electrolyte membrane. A step MEA may be configured.

  At that time, in order to reduce the amount of the relatively expensive solid polymer electrolyte membrane used and to protect the solid polymer electrolyte membrane having a thin film shape and low strength, an MEA with a resin frame incorporating a resin frame member is adopted. Has been. As this type of technology, for example, an electrolyte membrane / electrode structure with a fuel cell resin frame and a fuel cell stack disclosed in Patent Document 1 are known.

JP2013-98155A

  Incidentally, in the fuel cell stack described above, terminal plates, insulators, and end plates are disposed at both ends in the stacking direction of the stacked body in which a plurality of power generation cells are stacked. For this reason, especially in the power generation cell (end part cell unit) which comprises the both ends of the lamination direction of a layered product, it is most easily influenced by the fastening load of the lamination direction. Therefore, the resin frame member constituting the end cell unit has a problem that damage such as cracking occurs.

  The present invention solves this type of problem and provides a fuel cell stack capable of suppressing damage to a resin frame member constituting an end cell unit as much as possible with a simple configuration. The purpose is to do.

  The fuel cell stack according to the present invention comprises an electrolyte / electrode structure with a resin frame in which electrodes are disposed on both sides of the electrolyte membrane, and a resin frame member is provided around the outer periphery of the electrolyte membrane, and a separator. It has a power generation cell. The power generation cells are arranged as end cell units at both ends in the stacking direction of the laminate in which a plurality of power generation cells are stacked, and a terminal plate, an insulator, and an end plate are arranged outside each end cell unit. Has been.

  The resin frame member constituting the end cell unit has a contact surface that contacts the outermost separator disposed on the terminal plate side, and the contact surface has a gap between the outermost separator and the separator. Are provided.

  In the fuel cell stack, the contact surface is provided around the electrode, and a ring-shaped elastic member is preferably disposed in the escape groove.

  Further, each insulator is provided with a recess that opens toward the laminate, and at least the heat insulating member and the terminal plate are accommodated in the recess, and the escape groove is formed around the outer periphery of the recess. It is preferable.

  According to the present invention, the resin frame member has a contact surface that contacts the outermost separator, and the contact surface is provided with a relief groove. For this reason, the resin frame member is in contact with the separator on both sides of the escape groove, and it is possible to suppress an uneven load from acting on the resin frame member. Therefore, it is possible to suppress damage to the resin frame member constituting the end cell unit as much as possible with a simple configuration.

It is a perspective explanatory view of the fuel cell stack concerning the embodiment of the present invention. FIG. 2 is a partially exploded schematic perspective view of the fuel cell stack. FIG. 3 is a cross-sectional view of the fuel cell stack taken along line III-III in FIG. 2. It is a disassembled perspective explanatory drawing of the power generation cell which comprises the said fuel cell stack. It is a perspective explanatory view of an electrolyte membrane and electrode structure with a resin frame which constitutes an end cell unit.

  As shown in FIGS. 1 and 2, a fuel cell stack 10 according to an embodiment of the present invention includes a stacked body in which a plurality of power generation cells 12 are stacked in a horizontal direction (arrow A direction) or a gravity direction (arrow C direction). 14 and is mounted on a vehicle (not shown).

  A terminal plate 16a, an insulator (insulating plate) 18a, and an end plate 20a are sequentially disposed at one end in the stacking direction (arrow A direction) of the stacked body 14 (see FIG. 2). At the other end in the stacking direction of the stacked body 14, a terminal plate 16b, an insulator (insulating plate) 18b, and an end plate 20b are sequentially disposed outward.

  As shown in FIG. 1, the end plates 20 a and 20 b have a horizontally long (or vertically long) rectangular shape, and a connecting bar 24 is disposed between each side. Each connecting bar 24 is fixed at both ends to the inner surfaces of the end plates 20a and 20b via bolts 26, and applies a tightening load in the stacking direction (arrow A direction) to the plurality of stacked power generation cells 12. Note that the fuel cell stack 10 may include a housing having end plates 20a and 20b as end plates, and the stacked body 14 may be accommodated in the housing.

  As shown in FIGS. 3 and 4, the power generation cell 12 has a resin frame-attached electrolyte membrane / electrode structure 28 sandwiched between a first separator 30 and a second separator 32. For example, the first separator 30 and the second separator 32 are formed by pressing a steel plate, a stainless steel plate, an aluminum plate, a plated steel plate, or a metal thin plate having a metal surface subjected to a surface treatment for anticorrosion into a corrugated shape. . For example, a carbon separator may be used as the first separator 30 and the second separator 32 instead of the metal separator.

  One end edge of the power generation cell 12 in the arrow B direction (horizontal direction in FIG. 4), which is the long side direction, communicates with each other in the arrow A direction (stacking direction), and the oxidant gas inlet communication hole 34a, cooling medium An inlet communication hole 36a and a fuel gas outlet communication hole 38b are provided. The oxidant gas inlet communication hole 34a, the cooling medium inlet communication hole 36a, and the fuel gas outlet communication hole 38b are arranged in the direction of arrow C, and the oxidant gas inlet communication hole 34a is formed of an oxidant gas such as oxygen. Supply the contained gas. The cooling medium inlet communication hole 36a supplies a cooling medium, and the fuel gas outlet communication hole 38b discharges a fuel gas, for example, a hydrogen-containing gas.

  A fuel gas inlet communication hole 38a, a coolant outlet communication hole 36b, and an oxidant gas outlet communication hole 34b communicate with each other in the arrow A direction at the other end edge of the power generation cell 12 in the arrow B direction. Are provided in an array. The fuel gas inlet communication hole 38a supplies fuel gas, the cooling medium outlet communication hole 36b discharges the cooling medium, and the oxidant gas outlet communication hole 34b discharges the oxidant gas.

  For example, a fuel gas flow path 40 extending in the direction of arrow B is formed on the surface 30a of the first separator 30 facing the electrolyte membrane / electrode structure 28 with a resin frame. The fuel gas flow path 40 communicates with the fuel gas inlet communication hole 38a via the inlet passage portion 41a and also communicates with the fuel gas outlet communication hole 38b via the outlet passage portion 41b. The inlet passage 41a has an island-shaped portion integrally formed by a first seal member 46 described later, and a fuel gas inlet communication passage is formed between the island-shaped portions. Similarly, the outlet passage portion 41b has an island-shaped portion integrally formed by the first seal member 46, and a fuel gas outlet communication passage is formed between the island-shaped portions.

  On the surface 32a of the second separator 32 facing the electrolyte membrane / electrode structure 28 with a resin frame, for example, an oxidant gas flow path 42 extending in the arrow B direction is provided. The oxidant gas flow path 42 communicates with the oxidant gas inlet communication hole 34a through the inlet passage part 43a, and communicates with the oxidant gas outlet communication hole 34b through the outlet passage part 43b. The inlet passage 43a has an island-shaped portion integrally formed by a second seal member 48 described later, and an oxidant gas inlet communication passage is formed between the island-shaped portions. Similarly, the outlet passage portion 43b has an island-like portion integrally formed by the second seal member 48, and an oxidizing gas outlet communication passage is formed between the island-like portions.

  A cooling medium flow path 44 communicating with the cooling medium inlet communication hole 36a and the cooling medium outlet communication hole 36b is formed between the surface 30b of the first separator 30 and the surface 32b of the second separator 32 adjacent to each other. . The cooling medium flow path 44 is formed by overlapping the back surface shape of the first separator 30 in which the fuel gas flow path 40 is formed and the back surface shape of the second separator 32 in which the oxidant gas flow path 42 is formed.

  The first seal member 46 is integrated with the surfaces 30 a and 30 b of the first separator 30 around the outer peripheral end of the first separator 30. The second seal member 48 is integrated with the surfaces 32 a and 32 b of the second separator 32 around the outer peripheral end portion of the second separator 32.

  As shown in FIG. 3, the first seal member 46 is provided on the surface 30 a side, and is a first convex seal that abuts on a resin frame member 56 (described later) constituting the electrolyte membrane / electrode structure 28 with a resin frame. 46a. The first seal member 46 includes a second convex seal 46b and a third convex seal 46c that are provided on the surface 30b side and are double seals that contact the second seal member 48 of the adjacent second separator 32. The second seal member 48 includes a fourth convex seal 48 a that is provided on the surface 32 a side and abuts against the first seal member 46. In place of the fourth convex seal 48a, a convex seal (not shown) may be provided on the first seal member 46.

  For the first seal member 46 and the second seal member 48, for example, EPDM, NBR, fluorine rubber, silicone rubber, fluorosilicone rubber, butyl rubber, natural rubber, styrene rubber, chloroprene or acrylic rubber or the like, cushion material Alternatively, an elastic seal member such as a packing material is used.

  The electrolyte membrane / electrode structure 28 with a resin frame includes an electrolyte membrane / electrode structure 28a which is a step MEA. The electrolyte membrane / electrode structure 28a includes, for example, a solid polymer electrolyte membrane (cation exchange membrane) 50 in which a perfluorosulfonic acid thin film is impregnated with water, and an anode electrode 52 sandwiching the solid polymer electrolyte membrane 50. And a cathode electrode 54. The solid polymer electrolyte membrane 50 may use an HC (hydrocarbon) electrolyte in addition to the fluorine electrolyte.

  The cathode electrode 54 has a smaller planar dimension (outer dimension) than the solid polymer electrolyte membrane 50 and the anode electrode 52. Instead of the above configuration, the anode electrode 52 may be configured to have a smaller planar dimension than the solid polymer electrolyte membrane 50 and the cathode electrode 54.

  The anode electrode 52 includes a first electrode catalyst layer 52a bonded to one surface 50a of the solid polymer electrolyte membrane 50, and a first gas diffusion layer 52b stacked on the first electrode catalyst layer 52a. The first electrode catalyst layer 52a and the first gas diffusion layer 52b have the same external dimensions and are set to the same external dimensions as (or less than) the solid polymer electrolyte membrane 50.

  The cathode electrode 54 includes a second electrode catalyst layer 54a bonded to the surface 50b of the solid polymer electrolyte membrane 50, and a second gas diffusion layer 54b laminated on the second electrode catalyst layer 54a. The second electrode catalyst layer 54 a and the second gas diffusion layer 54 b have the same (or different) outer dimensions, and are set to be smaller than the outer dimensions of the solid polymer electrolyte membrane 50.

  The first electrode catalyst layer 52a is formed, for example, by uniformly applying porous carbon particles having a platinum alloy supported on the surface thereof to the surface of the first gas diffusion layer 52b. The second electrode catalyst layer 54a is formed, for example, by uniformly applying porous carbon particles carrying a platinum alloy on the surface thereof to the surface of the second gas diffusion layer 54b. The first gas diffusion layer 52b and the second gas diffusion layer 54b are made of carbon paper, carbon cloth, or the like. The first electrode catalyst layer 52 a and the second electrode catalyst layer 54 a are formed on both surfaces 50 a and 50 b of the solid polymer electrolyte membrane 50.

  The resin membrane-attached electrolyte membrane / electrode structure 28 includes a frame-shaped resin frame member 56 that goes around the outer periphery of the solid polymer electrolyte membrane 50 and is joined to the anode electrode 52 and the cathode electrode 54. The resin frame member 56 includes, for example, PPS (polyphenylene sulfide), PPA (polyphthalamide), PEN (polyethylene naphthalate), PES (polyethersulfone), LCP (liquid crystal polymer), PVDF (polyvinylidene fluoride), A silicone resin, a fluororesin, or m-PPE (modified polyphenylene ether resin) is used. In addition, the resin frame member 56 may be made of PET (polyethylene terephthalate), PBT (polybutylene terephthalate), or modified polyolefin.

  The resin frame member 56 includes a thin-walled inner bulging portion 56a to which the outer peripheral edge portion of the solid polymer electrolyte membrane 50 is bonded and a thin-walled outer bulge in which the first convex seal 46a of the first seal member 46 abuts. And a protruding portion 56b.

  As shown in FIG. 3, the power generation cells 12 are arranged as end cell units 12 </ b> A and 12 </ b> B at both ends in the stacking direction of the stacked body 14. The end cell unit 12A is disposed on the terminal plate 16a side, while the end cell unit 12B is disposed on the terminal plate 16b side.

In the end cell units 12A and 12B, the electrolyte membrane / electrode structures 28A and 28B with a resin frame are sandwiched between the first separator 30 and the second separator 32. The resin frame-attached electrolyte membrane / electrode structure 28A includes a resin frame member 56A. The resin frame member 56A has a contact surface 58a with which a part of the resin frame member 56A comes into contact with the outermost first separator _30end disposed on the terminal plate 16a side.

As shown in FIGS. 3 and 5, the contact surface 58a is provided at the tip of the thick portion 56c with the resin frame member 56A having a large thickness, and the contact surface 58a is connected to the first separator 30 _end . A relief groove 60a having a rectangular cross section is formed between which a gap is formed. The sectional shape of the escape groove 60a is not particularly limited. The same applies to escape grooves 60b described later. As shown in FIG. 5, the contact surface 58a is provided around the electrolyte membrane / electrode structure 28a, and a ring-shaped elastic member, for example, an O-ring 62a is disposed in the escape groove 60a.

As shown in FIG. 3, the electrolyte membrane / electrode structure 28B with a resin frame includes a resin frame member 56B. The resin frame member 56B has a contact surface 58b with which a part of the resin frame member 56B comes into contact with the outermost second separator 32 _end disposed on the terminal plate 16b side.

The contact surface 58b is provided at the tip of the thick portion 56d with the resin frame member 56B having a larger thickness, and the contact surface 58b has a clearance groove 60b that forms a gap with the second separator 32 _end. Provided. The contact surface 58b is provided around the electrolyte membrane / electrode structure 28a, and a ring-shaped elastic member, for example, an O-ring 62b is disposed in the escape groove 60b.

  As shown in FIG. 2, terminal portions 64a and 64b extending outward in the stacking direction are provided at substantially the center of the terminal plates 16a and 16b. The terminal portions 64a and 64b are inserted into the insulating cylinders 66a and 66b and pass through the holes 68a and 68b of the insulators 18a and 18b and the holes 70a and 70b of the end plates 20a and 20b. Project outside.

  The insulators 18a and 18b are made of an insulating material such as polycarbonate (PC) or phenol resin. In the central portions of the insulators 18a and 18b, recesses 72a and 72b that open toward the laminated body 14 are formed, and the recesses 72a and 72b communicate with the holes 68a and 68b.

  As shown in FIGS. 2 and 3, the terminal plate 16a and the heat insulating member 78a are accommodated in the concave portion 72a, while the terminal plate 16b and the heat insulating member 78b are accommodated in the concave portion 72b. In the heat insulating member 78a, a second heat insulating member 82a is disposed between the pair of first heat insulating members 80a. For example, the first heat insulating member 80a is formed of a carbon plate having a flat shape, and the second heat insulating member 82a is formed of, for example, a corrugated metal plate. The second heat insulating member 82a may be made of the same material as the first heat insulating member 80a.

  Moreover, the heat insulation member 78b is comprised similarly to said heat insulation member 78a, replaces a with the same referential mark, and attaches b to the same component, The detailed description is abbreviate | omitted.

As shown in FIG. 3, in the electrolyte membrane / electrode structure 28A with a resin frame, the contact surface 58a of the resin frame member 56A is provided at a position that goes around the outer periphery of the recess 72a of the insulator 18a. The surface of the insulator 18a, the first separator 30 _end, and the contact surface 58a are overlapped along the stacking direction. The escape groove 60a is formed around the outer periphery of the recess 72a. The resin membrane-attached electrolyte membrane / electrode structure 28B side is configured in the same manner as the resin frame-attached electrolyte membrane / electrode structure 28A side.

  The operation of the fuel cell stack 10 configured as described above will be described below.

  First, as shown in FIG. 1, an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas inlet communication hole 34a of the end plate 20a. Fuel gas such as hydrogen-containing gas is supplied to the fuel gas inlet communication hole 38a of the end plate 20a. A cooling medium such as pure water, ethylene glycol, or oil is supplied to the cooling medium inlet communication hole 36a of the end plate 20a.

  As shown in FIG. 4, the oxidant gas is introduced into the oxidant gas flow path 42 of the second separator 32 from the oxidant gas inlet communication hole 34a. The oxidant gas moves in the direction of arrow B along the oxidant gas flow path 42 and is supplied to the cathode electrode 54 of the electrolyte membrane / electrode structure 28a.

  On the other hand, the fuel gas is introduced into the fuel gas flow path 40 of the first separator 30 from the fuel gas inlet communication hole 38a. The fuel gas moves in the direction of arrow B along the fuel gas flow path 40 and is supplied to the anode electrode 52 of the electrolyte membrane / electrode structure 28a.

  Therefore, in each electrolyte membrane / electrode structure 28a, the oxidant gas supplied to the cathode electrode 54 and the fuel gas supplied to the anode electrode 52 are in the second electrode catalyst layer 54a and the first electrode catalyst layer 52a. Then, it is consumed by an electrochemical reaction to generate electricity.

  Next, the oxidant gas consumed by being supplied to the cathode electrode 54 is discharged in the direction of arrow A along the oxidant gas outlet communication hole 34b. Similarly, the fuel gas consumed by being supplied to the anode electrode 52 is discharged in the direction of arrow A along the fuel gas outlet communication hole 38b.

  The cooling medium supplied to the cooling medium inlet communication hole 36 a is introduced into the cooling medium flow path 44 between the first separator 30 and the second separator 32 and then flows in the direction of arrow B. The cooling medium is discharged from the cooling medium outlet communication hole 36b after the electrolyte membrane / electrode structure 28a is cooled.

In this case, in this embodiment, as shown in FIG. 3, the electrolyte membrane / electrode structure 28A with a resin frame constituting the end cell unit 12A includes a resin frame member 56A. The resin frame member 56A has a contact surface 58a that contacts the first separator 30 _end , and a relief groove 60a is provided in the contact surface 58a.

  For this reason, the resin frame member 56A is in contact with the first separator 30 on both sides of the relief groove 60a, and has a substantially double-end support beam shape. Therefore, it is possible to suppress the uneven load from acting on the resin frame member 56A in a state where the fastening load is applied to the fuel cell stack 10 in the stacking direction. Thereby, the effect that it becomes possible to suppress as much as possible that the resin frame member 56A which comprises the edge part cell unit 12A with a simple structure is damaged is acquired.

Further, an O-ring 62a is disposed in the relief groove 60a of the resin frame member 56A. For this reason, the O-ring 62a has a buffering function and a gas leakage prevention function, suppresses a decrease in power generation performance, and has a buffering effect on the contact between the thick portion 56c of the resin frame member 56A and the first separator 30 _end. Have. The same effect can be obtained on the end cell unit 12B side.

  In the present embodiment, a so-called each cell cooling structure in which a cell unit in which an electrolyte membrane / electrode structure with a resin frame is sandwiched between two separators is formed, and a cooling medium flow path is formed between each cell unit. However, it is not limited to this. For example, a cell unit comprising three or more separators and two or more resin membrane-attached electrolyte membrane / electrode structures, and alternately stacking the separator and the resin membrane-attached electrolyte membrane / electrode structures, A so-called thinning cooling structure in which a cooling medium flow path is formed between the cell units may be employed.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell stack 12 ... Power generation cell 14 ... Laminated body 16a, 16b ... Terminal plate 18a, 18b ... Insulator 20a, 20b ... End plate 28, 28A, 28B ... Electrolyte membrane / electrode structure 28a with resin frame ... Electrolyte membrane / Electrode structure 30, 30 _end , 32, 32 _end ... separator 34a ... oxidant gas inlet communication hole 34b ... oxidant gas outlet communication hole 36a ... cooling medium inlet communication hole 36b ... cooling medium outlet communication hole 38a ... fuel gas inlet communication Hole 38b ... Fuel gas outlet communication hole 40 ... Fuel gas flow path 42 ... Oxidant gas flow path 44 ... Cooling medium flow path 46, 48 ... Seal member 50 ... Solid polymer electrolyte membrane 52 ... Anode electrode 54 ... Cathode electrode 56, 56A, 56B ... Resin frame member 56a ... Inner bulge portion 56b ... Outer bulge portion 56c, 56d ... Thick portion 58a, 58b ... Contact surfaces 60a, 60b ... Escape grooves 62a, 62b ... O-rings 72a, 72b ... Recesses 78a, 78b, 80a, 82a ... Thermal insulation members

Claims (3)

An electrode is provided on both sides of the electrolyte membrane, and includes a power generation cell having an electrolyte / electrode structure with a resin frame that is provided around the outer periphery of the electrolyte membrane and provided with a resin frame member, and a separator. The power generation cells are arranged as end cell units at both ends of the laminate in which the power generation cells are stacked, and a terminal plate, an insulator, and an end plate are arranged outside each end cell unit. A fuel cell stack,
The resin frame member constituting the end cell unit has a contact surface that contacts the separator at the outermost end disposed on the terminal plate side,
The fuel cell stack, wherein the contact surface is provided with a clearance groove that forms a gap with the outermost separator. The fuel cell stack according to claim 1, wherein the contact surface is provided around the electrode,
A fuel cell stack, wherein a ring-shaped elastic member is disposed in the escape groove. 3. The fuel cell stack according to claim 1, wherein each insulator is provided with a recess opened toward the stacked body, and at least the heat insulating member and the terminal plate are accommodated in the recess.
The fuel cell stack, wherein the escape groove is formed around the outer periphery of the recess.

Images