US20090311571A1 - Fuel cell stack - Google Patents
Fuel cell stack Download PDFInfo
- Publication number
- US20090311571A1 US20090311571A1 US12/483,864 US48386409A US2009311571A1 US 20090311571 A1 US20090311571 A1 US 20090311571A1 US 48386409 A US48386409 A US 48386409A US 2009311571 A1 US2009311571 A1 US 2009311571A1
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- United States
- Prior art keywords
- gravity
- stack
- fuel cell
- lower side
- cell stack
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- Abandoned
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/02—Details
- H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
- H01M8/0258—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/02—Details
- H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
- H01M8/0267—Collectors; Separators, e.g. bipolar separators; Interconnectors having heating or cooling means, e.g. heaters or coolant flow channels
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/10—Fuel cells with solid electrolytes
- H01M8/1007—Fuel cells with solid electrolytes with both reactants being gaseous or vaporised
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
- H01M8/241—Grouping of fuel cells, e.g. stacking of fuel cells with solid or matrix-supported electrolytes
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
- H01M8/241—Grouping of fuel cells, e.g. stacking of fuel cells with solid or matrix-supported electrolytes
- H01M8/242—Grouping of fuel cells, e.g. stacking of fuel cells with solid or matrix-supported electrolytes comprising framed electrodes or intermediary frame-like gaskets
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
- H01M8/2465—Details of groupings of fuel cells
- H01M8/247—Arrangements for tightening a stack, for accommodation of a stack in a tank or for assembling different tanks
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
- H01M8/2465—Details of groupings of fuel cells
- H01M8/247—Arrangements for tightening a stack, for accommodation of a stack in a tank or for assembling different tanks
- H01M8/2475—Enclosures, casings or containers of fuel cell stacks
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
- H01M8/2465—Details of groupings of fuel cells
- H01M8/2483—Details of groupings of fuel cells characterised by internal manifolds
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
- H01M8/2465—Details of groupings of fuel cells
- H01M8/247—Arrangements for tightening a stack, for accommodation of a stack in a tank or for assembling different tanks
- H01M8/248—Means for compression of the fuel cell stacks
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
Definitions
- the present invention relates to a fuel cell stack which includes a stack body formed by stacking a plurality of unit cells in a horizontal direction, and a pair of end plates sandwiching the stack body.
- Each of the unit cells includes an electrolyte electrode assembly and separators sandwiching the electrolyte electrode assembly.
- the electrolyte electrode assembly includes a pair of electrodes and an electrolyte interposed between the electrodes.
- a solid polymer electrolyte fuel cell employs an electrolyte membrane (electrolyte) comprising a polymer ion exchange membrane.
- the electrolyte membrane is interposed between an anode and a cathode to form a membrane electrode assembly.
- the membrane electrode assembly is sandwiched between separators to form a fuel cell.
- a predetermined number of (e.g., several tens to several hundreds of) fuel cells are stacked together to form a fuel cell stack to obtain the desired electrical energy.
- a fuel cell apparatus as disclosed in Japanese Laid-Open Patent Publication No. 2001-319673 is known.
- a fuel cell stack 3 and a compression stress regulator mechanism 4 are provided. Hydrogen from a hydrogen supply apparatus 1 and oxygen from an oxygen supply apparatus 2 are used as fuels for power generation in the fuel cell stack 3 .
- the compression stress regulator mechanism 4 regulates compression stress applied to the fuel cell stack 3 .
- the compression stress regulator mechanism 4 includes a surface pressure applying member 5 , a spherical body 6 , a screw 7 , and a motor 8 .
- the surface pressure applying member 5 is attached to an end of the fuel cell stack 3 .
- the surface pressure applying member 5 applies a surface pressure to the fuel cell stack 3 .
- the spherical body 6 applies an axial force uniformly to the surface pressure applying member 5 .
- the screw 7 applies the axial force to the spherical body 6 .
- the motor 8 rotates the screw 7 .
- compression stress is regulated to adjust the space for movement of water in the fuel cell stack 3 to achieve the desired humidification state in the fuel cell stack 3 .
- the spherical body 6 presses substantially the center of the surface pressure applying member 5 attached to the end of the fuel cell stack 3 , and the swelling difference in the direction of gravity, in the electrolyte membrane cannot be eliminated.
- the load is applied non-uniformly to the fuel cell stack 3 due to the difference in swelling.
- the casing is deformed undesirably.
- the present invention has been made to solve the problem of this type, and an object of the present invention is to provide a fuel cell stack in which stack deformation due to swelling difference in a direction of gravity of the electrolyte is suppressed suitably.
- the present invention relates to a fuel cell stack which comprises a stack body formed by stacking a plurality of unit cells in a horizontal direction. A pair of end plates sandwiches the stack body. Each of the unit cells includes an electrolyte electrode assembly and separators sandwiching the electrolyte electrode assembly.
- the electrolyte electrode assembly includes a pair of electrodes and an electrolyte interposed between the electrodes.
- the fuel cell stack has stack deformation prevention structure for limiting a change in an interval between the end plates on a lower side of the stack body in the direction of gravity to be not greater than a change in an interval between the end plates on an upper side of the stack body in the direction of gravity, due to swelling on the lower side of the stack body in the direction of gravity.
- the lower side of the stack body in the direction of gravity herein means the lower side relative to the center of the stack body in the direction of gravity.
- the upper side of the stack body in the direction of gravity herein means the upper side relative to the center of the stack body in the direction of gravity.
- the change in the interval between the end plates on the lower side of the stack body in the direction of gravity is limited to be not greater than the change in the interval between the end plates on the upper side of the stack body in the direction of gravity, due to the swelling on the lower side of the stack body in the direction of gravity.
- stack deformation due to swelling of the electrolyte is suppressed suitably.
- FIG. 1 is a partial exploded perspective view schematically showing a fuel cell stack according to a first embodiment of the present invention
- FIG. 2 is a partial cross sectional side view showing the fuel cell stack
- FIG. 3 is an exploded perspective view showing a unit cell of the fuel cell stack
- FIG. 4 is a perspective view showing the fuel cell stack
- FIG. 5 is a partial exploded perspective view schematically showing a fuel cell stack according to a second embodiment of the present invention.
- FIG. 6 is partial cross sectional side view showing a fuel cell stack according to a third embodiment of the present invention.
- FIG. 7 is a side view showing a unit cell of a fuel cell stack according to a fourth embodiment of the present invention.
- FIG. 8 is a side view showing a unit cell of a fuel cell stack according to a fifth embodiment of the present invention.
- FIG. 9 is a partial cross sectional view showing a fuel cell stack according to a sixth embodiment of the present invention.
- FIG. 10 is an exploded perspective view showing a unit cell of a fuel cell stack according to a seventh embodiment of the present invention.
- FIG. 11 is a cross sectional view showing the unit cell, taken along a line XI-XI in FIG. 10 ;
- FIG. 12 is a cross sectional view showing the unit cell, taken along a line XII-XII in FIG. 10 ;
- FIG. 13 is an exploded perspective view showing a unit cell of a fuel cell stack according to an eighth embodiment of the present invention.
- FIG. 14 is a cross sectional view showing the unit cell, taken along a line XIV-XIV in FIG. 13 ;
- FIG. 15 is a cross sectional view showing the unit cell, taken along a line XV-XV in FIG. 13 ;
- FIG. 16 is a view showing a conventional fuel cell apparatus.
- a fuel cell stack 10 includes a stack body 14 formed by stacking a plurality of unit cells 12 in a horizontal direction indicated by an arrow A. At one end of the stack body 14 in a stacking direction indicated by the arrow A, a terminal plate 16 a is provided. An insulating plate 18 a is provided outside the terminal plate 16 a , and an end plate 20 a is provided outside the insulating plate (insulator) 18 a . At the other end of the stack body 14 in the stacking direction, a terminal plate 16 b is provided.
- An insulating plate 18 b (insulator) is provided outside the terminal plate 16 b , and an end plate 20 b is provided outside the insulating plate 18 b .
- An insulating spacer member may be used as the insulating plate 18 b .
- the fuel cell stack 10 is placed in a box-shaped casing 24 including the rectangular and vertically elongate end plates 20 a , 20 b.
- each of the unit cells 12 is formed by sandwiching a membrane electrode assembly (electrolyte electrode assembly) 30 between a first metal separator 32 , and a second metal separator 34 .
- the first metal separator 32 and the second metal separator 34 are thin corrugated metal plates.
- Each of the membrane electrode assemblies 30 and the first and second metal separators 32 , 34 has a rectangular and vertically elongate shape.
- carbon separators may be used.
- an oxygen-containing gas supply passage 36 a for supplying an oxygen-containing gas and a fuel gas supply passage 38 a for supplying a fuel gas such as a hydrogen-containing gas are provided.
- the oxygen-containing gas supply passage 36 a and the fuel gas supply passage 38 a extend through the unit cell 12 in the direction indicated by the arrow A.
- a fuel gas discharge passage 38 b for discharging the fuel gas and an oxygen-containing gas discharge passage 36 b for discharging the oxygen-containing gas are provided.
- the fuel gas discharge passage 38 b and the oxygen-containing gas discharge passage 36 b extend through the unit cell 12 in the direction indicated by the arrow A.
- a coolant supply passage 40 a for supplying a coolant is provided at one end of the unit cell 12 in a lateral direction indicated by an arrow B.
- a coolant discharge passage 40 b for discharging the coolant is provided at the other end of the unit cell 12 in the lateral direction.
- the membrane electrode assembly 30 includes an anode 44 , a cathode 46 , and a solid polymer electrolyte membrane 42 interposed between the anode 44 and the cathode 46 .
- the solid polymer electrolyte membrane 42 is formed by impregnating a thin membrane of perfluorosulfonic acid with water, for example.
- Each of the anode 44 and the cathode 46 has a gas diffusion layer (not shown) such as a carbon paper, and an electrode catalyst layer (not shown) of platinum alloy supported on porous carbon particles.
- the carbon particles are deposited uniformly on the surface of the gas diffusion layer.
- the electrode catalyst layer of the anode 44 and the electrode catalyst layer of the cathode 46 are formed on both surfaces of the solid polymer electrolyte membrane 42 , respectively.
- the first metal separator 32 has a fuel gas flow field 48 on its surface 32 a facing the membrane electrode assembly 30 .
- the fuel gas flow field 48 extends in the direction indicated by the arrow C, and the fuel gas flow field 48 is connected between the fuel gas supply passage 38 a and the fuel gas discharge passage 38 b .
- a coolant flow field 50 is formed on a surface 32 b of the first metal separator 32 .
- the coolant flow field 50 extends in the direction indicated by the arrow B, and the coolant flow field 50 is connected between the coolant supply passage 40 a and the coolant discharge passage 40 b.
- the second metal separator 34 has an oxygen-containing gas flow field 52 on its surface 34 a facing the membrane electrode assembly 30 .
- the oxygen-containing gas flow field 52 extends in the direction indicated by the arrow C, and the oxygen-containing gas flow field 52 is connected between the oxygen-containing gas supply passage 36 a and the oxygen-containing gas discharge passage 36 b .
- the coolant flow field 50 is formed on a surface 34 b of the second metal separator 34 . That is, the coolant flow field 50 is formed by overlapping the surface 34 b of the second metal separator 34 and the surface 32 b of the first metal separator 32 .
- a first seal member 54 is formed integrally on the surfaces 32 a , 32 b of the first metal separator 32 , around the outer end of the first metal separator 32 .
- a second seal member 56 is formed integrally on the surfaces 34 a , 34 b of the second metal separator 34 , around the outer end of the second metal separator 34 .
- a seal 57 is interposed between the first and the second seal member 54 , 56 for preventing the outer end of the solid polymer electrolyte membrane 42 from directly contacting the casing 24 .
- a rod shaped terminal 58 a is provided at substantially the center of the terminal plate 16 a
- a rod shaped terminal 58 b is provided at substantially the center of the terminal plate 16 b
- the rod shaped terminals 58 a , 58 b protrude in the stacking direction.
- the terminals 58 a , 58 b pass through holes 59 a , 59 b formed at the center of the end plates 20 a , 20 b in the longitudinal direction and the lateral direction, and protrude to the outside.
- a load such as a travel motor is connected to the terminals 58 a , 58 b.
- the casing 24 includes the end plates 20 a , 20 b , a plurality of side plates 60 a to 60 d , angle members 62 a to 62 d , and coupling pins 64 a , 64 b .
- the side plates 60 a to 60 d are provided on sides of the stack body 14 .
- the angle members 62 a to 62 d are used for coupling adjacent ends of the side plates 60 a to 60 d together.
- the coupling pins 64 a , 64 b are used for coupling the end plates 20 a , 20 b and the side plates 60 a to 60 d .
- the coupling pins 64 a , 64 b have different lengths.
- the side plates 60 a to 60 d are thin metal plates.
- the side plates 60 a to 60 d and the angle members 62 a to 62 d are fixed together using bolts 65 to form the casing 24 (see FIG. 4 ).
- Each of upper and lower ends of the end plate 20 a has one first hinge 66 a .
- Each of upper and lower ends of the end plate 20 b has one first hinge 66 b .
- Each of left and right ends of the end plate 20 a has two first hinges 66 c .
- Each of left and right ends of the end plate 20 b has two first hinges 66 d.
- the side plates 60 a , 60 c are provided on opposite sides of the stack body 14 in the direction indicated by the arrow B. Each longitudinal end of the side plate 60 a in the longitudinal direction indicated by the arrow A has three second hinges 70 a . Each longitudinal end of the side plate 60 c in the longitudinal direction indicated by the arrow A has three second hinges 70 b .
- the side plate 60 b is provided on the upper side of the stack body 14
- the side plate 60 d is provided on the lower side of the stack body 14 .
- Each longitudinal end of the side plate 60 b has two second hinges 72 a .
- Each longitudinal end of the side plate 60 d has two second hinges 72 b.
- the first hinges 66 c of the end plate 20 a , and the first hinges 66 d of the end plate 20 b are positioned between the second hinges 70 a of the side plate 60 a , and between the second hinges 70 b of the side plate 60 c .
- the long coupling pins 64 a are inserted into these hinges 66 c , 66 d , 70 a , 70 b.
- the second hinges 72 a of the side plate 60 b and the first hinges 66 a , 66 b of the upper ends of the end plates 20 a , 20 b are positioned alternately, and the second hinges 72 b of the side plate 60 d and the first hinges 66 a , 66 b of the lower ends of the end plates 20 a , 20 b are positioned alternately.
- the short coupling pins 64 b are inserted into these hinges 66 a , 66 b , 72 a , 72 b.
- an oxygen-containing gas inlet 76 a and a fuel gas inlet 78 a are provided in the end plate 20 a .
- the oxygen-containing gas inlet 76 a is connected to the oxygen-containing gas supply passage 36 a
- the fuel gas inlet 78 a is connected to the fuel gas supply passage 38 a .
- an oxygen-containing gas outlet 76 b and a fuel gas outlet 78 b are provided in the end plate 20 a .
- the oxygen-containing gas outlet 76 b is connected to the oxygen-containing gas discharge passage 36 b
- the fuel gas outlet 78 b is connected to the fuel gas discharge passage 38 b.
- a coolant inlet 80 a and a coolant outlet 80 b are provided in the end plate 20 b .
- the coolant inlet 80 a is connected to the coolant supply passage 40 a
- the coolant outlet 80 b is connected to the coolant discharge passage 40 b.
- the casing 24 has stack deformation prevention structure 82 for limiting the change in the interval between the end plates 20 a , 20 b on the lower side in a direction of gravity due to swelling on the lower side of the stack body 14 in the direction of gravity.
- the lower side of the stack body 14 in the direction of gravity herein means the lower side relative to the center of the stack body 14 in the direction of gravity.
- the upper side of the stack body 14 in the direction of gravity herein means the upper side relative to the center of the stack body 14 in the direction of gravity.
- the change in the interval between the end plates 20 a , 20 b due to swelling of the stack body 14 depends on the total deformation amount in the stacking direction indicated by the arrow A of the solid polymer electrolyte membranes 42 of the membrane electrode assemblies 30 of the respective unit cells 12 , when the solid polymer electrolyte membranes 42 are swelled by water.
- the stack deformation prevention structure 82 is configured such that elastic modulus in the stacking direction of the side plate 60 d provided on the lower side of the stack body 14 in the direction of gravity becomes higher than elastic modulus in the stacking direction of the side plate 60 b provided on the upper side in the direction of gravity.
- a plurality of thick portions (or separate plate members) 84 extending in the direction indicated by the arrow A are provided on the bottom side of the side plate 60 d .
- the thickness of the side plate 60 d on the lower side may be larger than the thickness of the side plate 60 b on the upper side.
- an oxygen-containing gas is supplied to the oxygen-containing gas inlet 76 a of the end plate 20 a
- a fuel gas such as a hydrogen-containing gas is supplied to the fuel gas inlet 78 a
- a coolant such as pure water or ethylene glycol is supplied to the coolant inlet 80 a of the end plate 20 b.
- the oxygen-containing gas, the fuel gas, and the coolant are supplied to the oxygen-containing gas supply passage 36 a , the fuel gas supply passage 38 a and the coolant supply passage 40 a in the direction indicated by the arrow A.
- the oxygen-containing gas is supplied from the oxygen-containing gas supply passage 36 a to the oxygen-containing gas flow field 52 of the second metal separator 34 , and flows along the cathode 46 of the membrane electrode assembly 30 .
- the fuel gas is supplied from the fuel gas supply passage 38 a to the fuel gas flow field 48 of the first metal separator 32 , and flows along the anode 44 of the membrane electrode assembly 30 .
- the oxygen-containing gas supplied to the cathode 46 , and the fuel gas supplied to the anode 44 are partially consumed in the electrochemical reactions at catalyst layers of the cathode 46 and the anode 44 for generating electricity.
- the oxygen-containing gas partially consumed at the cathode 46 flows along the oxygen-containing gas discharge passage 36 b , and is discharged to the outside through the oxygen-containing gas outlet 76 b at the end plate 20 b (see FIG. 4 ).
- the fuel gas partially consumed at the anode 44 flows through the fuel gas discharge passage 38 b , and is discharged to the outside through the fuel gas outlet 78 b at the end plate 20 a.
- the coolant flows into the coolant flow field 50 between the first and second metal separators 32 , 34 from the coolant supply passage 40 a , and flows in the direction indicated by the arrow B. After the coolant cools the membrane electrode assembly 30 , the coolant moves through the coolant discharge passage 40 b , and the coolant is discharged through the coolant outlet 80 b at the end plate 20 b (see FIG. 1 ).
- the solid polymer electrolyte membrane 42 is swelled by water produced in the power generation. At this time, since the produced water moves in the direction of gravity, the lower side of the solid polymer electrolyte membrane 42 in the direction of gravity is swelled significantly. In particular, in the case where the membrane electrode assembly 30 has a longitudinally elongated shape, the difference in swelling in the direction of gravity becomes significantly large.
- the thickness on the lower side in the direction of gravity becomes significantly larger than the thickness on the upper side in the direction of gravity. Therefore, a large dimensional difference in the stacking direction tends to occur, between the lower side and the upper side in a vertical direction in the stack body 14 as a whole.
- the casing 24 has the stack deformation prevention structure 82 .
- the stack deformation prevention structure 82 is configured such that the elastic modulus of the side plate 60 d as the bottom plate is higher than the elastic modulus of the side plate 60 b of the top plate. Therefore, even if a large stress is applied to the lower side of the stack body 14 in the direction of gravity in comparison with the upper side of the stack body 14 in the direction of gravity, due to the difference of swelling in each of solid polymer electrolyte membranes 42 , the stress can be supported by the elastic modulus of the side plate 60 d.
- FIG. 5 is a partial exploded perspective view showing a fuel cell stack 90 according to a second embodiment of the present invention.
- the constituent elements that are identical to those of the fuel cell stack 10 according to the first embodiment are labeled with the same reference numeral, and description thereof will be omitted. Further, also in third to eighth embodiments as described later, the constituent elements that are identical to those of the fuel cell stack 10 according to the first embodiment are labeled with the same reference numeral, and description thereof will be omitted.
- the side plates 60 a , 60 c of the casing 24 have stack deformation prevention structure 92 .
- Each of the side pates 60 a , 60 c has two plate members 94 a , 94 b .
- the stack deformation prevention structure 92 is configured such that the thickness of the plate member 94 a is larger than the thickness of the plate member 94 b . Therefore, even if a large stress is applied to the lower side of the stack body 14 in the direction of gravity in comparison with the upper side of the stack body 14 in the direction of gravity, due to the difference of swelling in each of the solid polymer electrolyte membranes 42 , the stress can be supported by the elastic modulus of the plate member 94 a.
- each of the side plates 60 a , 60 c includes the two plate members 94 a , 94 b .
- each of the side plates 60 a , 60 c may comprise only a single plate, and the thickness of the plate may be increased continuously or stepwise from the upper side of the stack body 14 in the direction of gravity to the lower side of the stack body 14 in the direction of gravity.
- FIG. 6 is a partial cross sectional view showing a fuel cell stack 100 according to a third embodiment of the present invention.
- each of the unit cells 12 has stack deformation prevention structure 102 .
- the stack deformation prevention structure 102 is configured such that elastic modulus of ends 54 a , 56 a on the upper side of the first and second seal members 54 , 56 in the direction of gravity is higher than elastic modulus of ends 54 b , 56 b on the lower side of the first and second seal members 54 , 56 in the direction of gravity. Specifically, cross sectional areas of the first and second seal members 54 , 56 or materials of the first and second seal members 54 , 56 are changed for changing the elastic modulus.
- elastic modulus of the ends 54 a , 56 a on the upper side of the first and second seal members 54 , 56 in the direction of gravity is higher than elastic modulus of the ends 54 b , 56 b on the lower side of the first and second seal members 54 , 56 in the direction of gravity. Therefore, the load supported by the ends 54 a , 56 a of the first and second seal members 54 , 56 is larger than the load supported by the ends 54 b , 56 b of the first and second seal members 54 , 56 .
- FIG. 7 is a side view showing a unit cell 12 of a fuel cell stack 110 according to a fourth embodiment of the present invention.
- each of the unit cells 12 has stack deformation prevention structure 112 .
- the stack deformation prevention structure 112 is configured such that the thickness (t 1 ) on the lower side of the first and second metal separators 32 , 34 in the direction of gravity is smaller than the thickness (t 2 ) on the upper side of the first and second metal separators 32 , 34 in the direction of gravity (t 1 ⁇ t 2 ).
- each solid polymer electrolyte membrane 42 in the direction of gravity is absorbed easily by deformation of the first and second metal separators 32 , 34 , and the dimension (interval) in the stacking direction between the end plates 20 a , 20 b does not change in the fuel cell stack 110 as a whole.
- FIG. 8 is a side view showing a unit cell 12 of a fuel cell stack 120 according to a fifth embodiment of the present invention.
- each of the unit cells 12 has stack deformation prevention structure 122 .
- the stack deformation prevention structure 122 is configured such that the thickness (t 3 ) on the lower side of the solid polymer electrolyte membrane 42 of the membrane electrode assembly 30 in the direction of gravity is smaller than the thickness (t 4 ) on the upper side of the solid polymer electrolyte membrane 42 in the direction of gravity.
- the solid polymer electrolyte membrane 42 is swelled by absorption of water produced in the power generation.
- the thickness (t 3 ) on the lower side of the solid polymer electrolyte membrane 42 in the direction of gravity, i.e., the thickness on the side where the amount of the produced water is large is smaller than the thickness (t 4 ) on the upper side of the solid polymer electrolyte membrane 42 in the direction of gravity, i.e., the thickness on the side where the amount of the produced water is small.
- the thickness of the solid polymer electrolyte membrane 42 becomes substantially uniform along the direction of gravity, and it becomes possible to inhibit application of the non-uniform load to the fuel cell stack 120 .
- FIG. 9 is a partial cross sectional view showing a fuel cell stack 130 according to a sixth embodiment of the present invention.
- the fuel cell stack 130 has stack deformation prevention structure 132 .
- the stack deformation prevention structure 132 is configured such that tapered surfaces 134 a , 134 b are provided in each of the inner surfaces of the end plates 20 a , 20 b , and the tapered surfaces 134 a , 134 b are slanted outwardly, toward the lower side in the direction of gravity.
- the interval between the end plates 20 a , 20 b on the lower side in the direction of gravity is larger than the interval between the end plates 20 a , 20 b on the upper side in the direction of gravity (see distance t 5 ).
- the end plates 20 a , 20 b have the tapered surfaces 134 a , 134 b .
- the insulating plates 18 a , 18 b or the terminal plates 16 a , 16 b may have the similar tapered surfaces (not shown).
- FIG. 10 is an exploded perspective view showing a unit cell 140 of a fuel cell stack according to a seventh embodiment of the present invention.
- the unit cell 140 has first and second metal separators 142 , 144 sandwiching the membrane electrode assembly 30 .
- the first and second metal separators 142 , 144 are corrugated thin plates. By corrugating the first metal separator 142 , a fuel gas flow field 48 is formed on a surface of the first metal separator 142 facing the membrane electrode assembly 30 , and by corrugating the second metal separator 144 , an oxygen-containing gas flow field 52 is formed on a surface of the second metal separator 144 facing the membrane electrode assembly 30 .
- the fuel gas flow field 48 and the oxygen-containing gas flow field 52 has a cross sectional shape as shown in FIG. 11 on the upper side of the stack body 14 in the direction of gravity and a cross sectional shape as shown in FIG. 12 on the lower side of the stack body 14 in the direction of gravity.
- elastic modulus in the stacking direction, on the lower side of the stack body 14 in the direction of gravity is smaller than elastic modulus in the stacking direction, on the upper side of the stack body 14 in the direction of gravity. That is, the lower side of the stack body 14 can be deformed easily.
- the unit cell 140 is deformed easily in the stacking direction, on the lower side in the direction of gravity, in comparison with the upper side in the direction of gravity. Therefore, the same advantages as in the case of the fourth embodiment are obtained. For example, swelling on the lower side of the solid polymer electrolyte membrane 42 in the direction of gravity is absorbed easily by deformation of the first and second metal separators 142 , 144 .
- FIG. 13 is an exploded perspective view showing a unit cell 150 of a fuel cell stack according to an eighth embodiment of the present invention.
- the unit cell 150 has first and second metal separators 152 , 154 sandwiching the membrane electrode assembly 30 .
- the first and second metal separators 152 , 154 are corrugated thin plates.
- a fuel gas flow field 48 is formed on a surface of the first metal separator 152 facing the membrane electrode assembly 30
- an oxygen-containing gas flow field 52 is formed on a surface of the second metal separator 154 facing the membrane electrode assembly 30 .
- the fuel gas flow field 48 and the oxygen-containing gas flow field 52 has a cross sectional shape as shown in FIG. 14 on the upper side of the stack body 14 in the direction of gravity and a cross sectional shape as shown in FIG. 15 on the lower side of the stack body 14 in the direction of gravity.
- elastic modulus in the stacking direction, on the lower side of the stack body 14 in the direction of gravity is smaller than elastic modulus in the stacking direction, on the upper side of the stack body 14 in the direction of gravity. That is, the lower side of the stack body 14 can be deformed easily.
- the same advantages as in the case of the seventh embodiment are obtained. For example, swelling in the direction of gravity, on the lower side of the solid polymer electrolyte membrane 42 is absorbed easily by deformation of the first and second metal separators 152 , 154 .
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Abstract
A casing of a fuel cell stack has stack deformation prevention structure for limiting the change of an interval between end plates on the lower side in a direction of gravity, due to swelling of the lower side of the stack body in the direction of gravity. The stack deformation prevention structure is configured such that elastic modulus of a side plate provided on a lower side of the stack body in the direction of gravity is higher than elastic modulus of a side plate provided on an upper side of the stack body in the direction of gravity.
Description
- 1. Field of the Invention
- The present invention relates to a fuel cell stack which includes a stack body formed by stacking a plurality of unit cells in a horizontal direction, and a pair of end plates sandwiching the stack body. Each of the unit cells includes an electrolyte electrode assembly and separators sandwiching the electrolyte electrode assembly. The electrolyte electrode assembly includes a pair of electrodes and an electrolyte interposed between the electrodes.
- 2. Description of the Related Art
- For example, a solid polymer electrolyte fuel cell employs an electrolyte membrane (electrolyte) comprising a polymer ion exchange membrane. The electrolyte membrane is interposed between an anode and a cathode to form a membrane electrode assembly. The membrane electrode assembly is sandwiched between separators to form a fuel cell. In use, normally, a predetermined number of (e.g., several tens to several hundreds of) fuel cells are stacked together to form a fuel cell stack to obtain the desired electrical energy.
- At the time of power generation in the fuel cell, by electrochemical reactions of hydrogen and oxygen, water is produced. Therefore, the power generation performance tends to be changed easily depending on the internal state of the produced water. Therefore, the state of the produced water needs to be managed suitably.
- In this regard, for example, a fuel cell apparatus as disclosed in Japanese Laid-Open Patent Publication No. 2001-319673 is known. In the conventional technique, as shown in
FIG. 16 , afuel cell stack 3 and a compressionstress regulator mechanism 4 are provided. Hydrogen from ahydrogen supply apparatus 1 and oxygen from anoxygen supply apparatus 2 are used as fuels for power generation in thefuel cell stack 3. The compressionstress regulator mechanism 4 regulates compression stress applied to thefuel cell stack 3. - The compression
stress regulator mechanism 4 includes a surfacepressure applying member 5, aspherical body 6, a screw 7, and amotor 8. The surfacepressure applying member 5 is attached to an end of thefuel cell stack 3. The surfacepressure applying member 5 applies a surface pressure to thefuel cell stack 3. Thespherical body 6 applies an axial force uniformly to the surfacepressure applying member 5. The screw 7 applies the axial force to thespherical body 6. Themotor 8 rotates the screw 7. - According to the disclosure, by operation of the compression
stress regulator mechanism 4, compression stress is regulated to adjust the space for movement of water in thefuel cell stack 3 to achieve the desired humidification state in thefuel cell stack 3. - In the
fuel cell stack 3, swelling of the electrolyte membrane occurs by the water produced in the power generation. In particular, swelled portion becomes large, in particular, on the lower side in the direction of gravity. Thus, difference in swelling occurs in the electrolyte membrane along the direction of gravity. - However, in the conventional technique, the
spherical body 6 presses substantially the center of the surfacepressure applying member 5 attached to the end of thefuel cell stack 3, and the swelling difference in the direction of gravity, in the electrolyte membrane cannot be eliminated. Thus, for example, when thefuel cell stack 3 is placed in a casing (box), the load is applied non-uniformly to thefuel cell stack 3 due to the difference in swelling. As a result, the casing is deformed undesirably. - The present invention has been made to solve the problem of this type, and an object of the present invention is to provide a fuel cell stack in which stack deformation due to swelling difference in a direction of gravity of the electrolyte is suppressed suitably.
- The present invention relates to a fuel cell stack which comprises a stack body formed by stacking a plurality of unit cells in a horizontal direction. A pair of end plates sandwiches the stack body. Each of the unit cells includes an electrolyte electrode assembly and separators sandwiching the electrolyte electrode assembly. The electrolyte electrode assembly includes a pair of electrodes and an electrolyte interposed between the electrodes.
- The fuel cell stack has stack deformation prevention structure for limiting a change in an interval between the end plates on a lower side of the stack body in the direction of gravity to be not greater than a change in an interval between the end plates on an upper side of the stack body in the direction of gravity, due to swelling on the lower side of the stack body in the direction of gravity.
- The lower side of the stack body in the direction of gravity herein means the lower side relative to the center of the stack body in the direction of gravity. The upper side of the stack body in the direction of gravity herein means the upper side relative to the center of the stack body in the direction of gravity.
- In the present invention, in the presence of the stack deformation prevention structure, the change in the interval between the end plates on the lower side of the stack body in the direction of gravity is limited to be not greater than the change in the interval between the end plates on the upper side of the stack body in the direction of gravity, due to the swelling on the lower side of the stack body in the direction of gravity. Thus, stack deformation due to swelling of the electrolyte is suppressed suitably.
- The above and other objects, features and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which preferred embodiments of the present invention are shown by way of illustrative example.
-
FIG. 1 is a partial exploded perspective view schematically showing a fuel cell stack according to a first embodiment of the present invention; -
FIG. 2 is a partial cross sectional side view showing the fuel cell stack; -
FIG. 3 is an exploded perspective view showing a unit cell of the fuel cell stack; -
FIG. 4 is a perspective view showing the fuel cell stack; -
FIG. 5 is a partial exploded perspective view schematically showing a fuel cell stack according to a second embodiment of the present invention; -
FIG. 6 is partial cross sectional side view showing a fuel cell stack according to a third embodiment of the present invention; -
FIG. 7 is a side view showing a unit cell of a fuel cell stack according to a fourth embodiment of the present invention; -
FIG. 8 is a side view showing a unit cell of a fuel cell stack according to a fifth embodiment of the present invention; -
FIG. 9 is a partial cross sectional view showing a fuel cell stack according to a sixth embodiment of the present invention; -
FIG. 10 is an exploded perspective view showing a unit cell of a fuel cell stack according to a seventh embodiment of the present invention; -
FIG. 11 is a cross sectional view showing the unit cell, taken along a line XI-XI inFIG. 10 ; -
FIG. 12 is a cross sectional view showing the unit cell, taken along a line XII-XII inFIG. 10 ; -
FIG. 13 is an exploded perspective view showing a unit cell of a fuel cell stack according to an eighth embodiment of the present invention; -
FIG. 14 is a cross sectional view showing the unit cell, taken along a line XIV-XIV inFIG. 13 ; -
FIG. 15 is a cross sectional view showing the unit cell, taken along a line XV-XV inFIG. 13 ; and -
FIG. 16 is a view showing a conventional fuel cell apparatus. - As shown in
FIGS. 1 and 2 , afuel cell stack 10 according to a first embodiment of the present invention includes astack body 14 formed by stacking a plurality ofunit cells 12 in a horizontal direction indicated by an arrow A. At one end of thestack body 14 in a stacking direction indicated by the arrow A, aterminal plate 16 a is provided. Aninsulating plate 18 a is provided outside theterminal plate 16 a, and anend plate 20 a is provided outside the insulating plate (insulator) 18 a. At the other end of thestack body 14 in the stacking direction, aterminal plate 16 b is provided. An insulatingplate 18 b (insulator) is provided outside theterminal plate 16 b, and anend plate 20 b is provided outside the insulatingplate 18 b. An insulating spacer member may be used as the insulatingplate 18 b. Thefuel cell stack 10 is placed in a box-shapedcasing 24 including the rectangular and verticallyelongate end plates - As shown in
FIGS. 2 and 3 , each of theunit cells 12 is formed by sandwiching a membrane electrode assembly (electrolyte electrode assembly) 30 between afirst metal separator 32, and asecond metal separator 34. Thefirst metal separator 32 and thesecond metal separator 34 are thin corrugated metal plates. Each of themembrane electrode assemblies 30 and the first andsecond metal separators second metal separators - At one end (upper end) of the
unit cell 12 in a longitudinal direction indicated by an arrow C inFIG. 3 , an oxygen-containinggas supply passage 36 a for supplying an oxygen-containing gas and a fuelgas supply passage 38 a for supplying a fuel gas such as a hydrogen-containing gas are provided. The oxygen-containinggas supply passage 36 a and the fuelgas supply passage 38 a extend through theunit cell 12 in the direction indicated by the arrow A. - At the other end (lower end) of the
unit cell 12 in the longitudinal direction, a fuelgas discharge passage 38 b for discharging the fuel gas and an oxygen-containinggas discharge passage 36 b for discharging the oxygen-containing gas are provided. The fuelgas discharge passage 38 b and the oxygen-containinggas discharge passage 36 b extend through theunit cell 12 in the direction indicated by the arrow A. - At one end of the
unit cell 12 in a lateral direction indicated by an arrow B, acoolant supply passage 40 a for supplying a coolant is provided. At the other end of theunit cell 12 in the lateral direction, acoolant discharge passage 40 b for discharging the coolant is provided. - The
membrane electrode assembly 30 includes ananode 44, acathode 46, and a solidpolymer electrolyte membrane 42 interposed between theanode 44 and thecathode 46. The solidpolymer electrolyte membrane 42 is formed by impregnating a thin membrane of perfluorosulfonic acid with water, for example. - Each of the
anode 44 and thecathode 46 has a gas diffusion layer (not shown) such as a carbon paper, and an electrode catalyst layer (not shown) of platinum alloy supported on porous carbon particles. The carbon particles are deposited uniformly on the surface of the gas diffusion layer. The electrode catalyst layer of theanode 44 and the electrode catalyst layer of thecathode 46 are formed on both surfaces of the solidpolymer electrolyte membrane 42, respectively. - The
first metal separator 32 has a fuelgas flow field 48 on itssurface 32 a facing themembrane electrode assembly 30. The fuelgas flow field 48 extends in the direction indicated by the arrow C, and the fuelgas flow field 48 is connected between the fuelgas supply passage 38 a and the fuelgas discharge passage 38 b. Acoolant flow field 50 is formed on asurface 32 b of thefirst metal separator 32. Thecoolant flow field 50 extends in the direction indicated by the arrow B, and thecoolant flow field 50 is connected between thecoolant supply passage 40 a and thecoolant discharge passage 40 b. - The
second metal separator 34 has an oxygen-containinggas flow field 52 on itssurface 34 a facing themembrane electrode assembly 30. The oxygen-containinggas flow field 52 extends in the direction indicated by the arrow C, and the oxygen-containinggas flow field 52 is connected between the oxygen-containinggas supply passage 36 a and the oxygen-containinggas discharge passage 36 b. Thecoolant flow field 50 is formed on asurface 34 b of thesecond metal separator 34. That is, thecoolant flow field 50 is formed by overlapping thesurface 34 b of thesecond metal separator 34 and thesurface 32 b of thefirst metal separator 32. - A
first seal member 54 is formed integrally on thesurfaces first metal separator 32, around the outer end of thefirst metal separator 32. Asecond seal member 56 is formed integrally on thesurfaces second metal separator 34, around the outer end of thesecond metal separator 34. - As shown in
FIG. 2 , aseal 57 is interposed between the first and thesecond seal member polymer electrolyte membrane 42 from directly contacting thecasing 24. - As shown in
FIG. 1 , a rod shaped terminal 58 a is provided at substantially the center of theterminal plate 16 a, and a rod shaped terminal 58 b is provided at substantially the center of theterminal plate 16 b. The rod shapedterminals terminals holes end plates terminals - As shown in
FIG. 1 , thecasing 24 includes theend plates side plates 60 a to 60 d,angle members 62 a to 62 d, and coupling pins 64 a, 64 b. Theside plates 60 a to 60 d are provided on sides of thestack body 14. Theangle members 62 a to 62 d are used for coupling adjacent ends of theside plates 60 a to 60 d together. The coupling pins 64 a, 64 b are used for coupling theend plates side plates 60 a to 60 d. The coupling pins 64 a, 64 b have different lengths. - For example, the
side plates 60 a to 60 d are thin metal plates. Theside plates 60 a to 60 d and theangle members 62 a to 62 d are fixed together usingbolts 65 to form the casing 24 (seeFIG. 4 ). - Each of upper and lower ends of the
end plate 20 a has onefirst hinge 66 a. Each of upper and lower ends of theend plate 20 b has onefirst hinge 66 b. Each of left and right ends of theend plate 20 a has twofirst hinges 66 c. Each of left and right ends of theend plate 20 b has twofirst hinges 66 d. - The
side plates stack body 14 in the direction indicated by the arrow B. Each longitudinal end of theside plate 60 a in the longitudinal direction indicated by the arrow A has threesecond hinges 70 a. Each longitudinal end of theside plate 60 c in the longitudinal direction indicated by the arrow A has threesecond hinges 70 b. Theside plate 60 b is provided on the upper side of thestack body 14, and theside plate 60 d is provided on the lower side of thestack body 14. Each longitudinal end of theside plate 60 b has twosecond hinges 72 a. Each longitudinal end of theside plate 60 d has twosecond hinges 72 b. - As shown in
FIG. 4 , the first hinges 66 c of theend plate 20 a, and the first hinges 66 d of theend plate 20 b are positioned between the second hinges 70 a of theside plate 60 a, and between the second hinges 70 b of theside plate 60 c. The long coupling pins 64 a are inserted into thesehinges - Likewise, the second hinges 72 a of the
side plate 60 b and the first hinges 66 a, 66 b of the upper ends of theend plates side plate 60 d and the first hinges 66 a, 66 b of the lower ends of theend plates hinges - As shown in
FIG. 1 , an oxygen-containinggas inlet 76 a and afuel gas inlet 78 a are provided in theend plate 20 a. The oxygen-containinggas inlet 76 a is connected to the oxygen-containinggas supply passage 36 a, and thefuel gas inlet 78 a is connected to the fuelgas supply passage 38 a. Further, an oxygen-containinggas outlet 76 b and afuel gas outlet 78 b are provided in theend plate 20 a. The oxygen-containinggas outlet 76 b is connected to the oxygen-containinggas discharge passage 36 b, and thefuel gas outlet 78 b is connected to the fuelgas discharge passage 38 b. - A
coolant inlet 80 a and acoolant outlet 80 b are provided in theend plate 20 b. Thecoolant inlet 80 a is connected to thecoolant supply passage 40 a, and thecoolant outlet 80 b is connected to thecoolant discharge passage 40 b. - The
casing 24 has stackdeformation prevention structure 82 for limiting the change in the interval between theend plates stack body 14 in the direction of gravity. - The lower side of the
stack body 14 in the direction of gravity herein means the lower side relative to the center of thestack body 14 in the direction of gravity. The upper side of thestack body 14 in the direction of gravity herein means the upper side relative to the center of thestack body 14 in the direction of gravity. By swelling of the lower side of thestack body 14 in the direction of gravity, the interval between theend plates - The change in the interval between the
end plates stack body 14 depends on the total deformation amount in the stacking direction indicated by the arrow A of the solidpolymer electrolyte membranes 42 of themembrane electrode assemblies 30 of therespective unit cells 12, when the solidpolymer electrolyte membranes 42 are swelled by water. - The stack
deformation prevention structure 82 is configured such that elastic modulus in the stacking direction of theside plate 60 d provided on the lower side of thestack body 14 in the direction of gravity becomes higher than elastic modulus in the stacking direction of theside plate 60 b provided on the upper side in the direction of gravity. Specifically, a plurality of thick portions (or separate plate members) 84 extending in the direction indicated by the arrow A are provided on the bottom side of theside plate 60 d. Alternatively, the thickness of theside plate 60 d on the lower side may be larger than the thickness of theside plate 60 b on the upper side. - Next, operation of the
fuel cell stack 10 will be described below. - As shown in
FIG. 4 , an oxygen-containing gas is supplied to the oxygen-containinggas inlet 76 a of theend plate 20 a, and a fuel gas such as a hydrogen-containing gas is supplied to thefuel gas inlet 78 a. Further, a coolant such as pure water or ethylene glycol is supplied to thecoolant inlet 80 a of theend plate 20 b. - Thus, in the
stack body 14 formed by stacking theunit cells 12 in the direction indicated by the arrow A, the oxygen-containing gas, the fuel gas, and the coolant are supplied to the oxygen-containinggas supply passage 36 a, the fuelgas supply passage 38 a and thecoolant supply passage 40 a in the direction indicated by the arrow A. - As shown in
FIG. 3 , the oxygen-containing gas is supplied from the oxygen-containinggas supply passage 36 a to the oxygen-containinggas flow field 52 of thesecond metal separator 34, and flows along thecathode 46 of themembrane electrode assembly 30. The fuel gas is supplied from the fuelgas supply passage 38 a to the fuelgas flow field 48 of thefirst metal separator 32, and flows along theanode 44 of themembrane electrode assembly 30. - Thus, in each of the
membrane electrode assemblies 30, the oxygen-containing gas supplied to thecathode 46, and the fuel gas supplied to theanode 44 are partially consumed in the electrochemical reactions at catalyst layers of thecathode 46 and theanode 44 for generating electricity. - Then, the oxygen-containing gas partially consumed at the
cathode 46 flows along the oxygen-containinggas discharge passage 36 b, and is discharged to the outside through the oxygen-containinggas outlet 76 b at theend plate 20 b (seeFIG. 4 ). Likewise, the fuel gas partially consumed at theanode 44 flows through the fuelgas discharge passage 38 b, and is discharged to the outside through thefuel gas outlet 78 b at theend plate 20 a. - Further, the coolant flows into the
coolant flow field 50 between the first andsecond metal separators coolant supply passage 40 a, and flows in the direction indicated by the arrow B. After the coolant cools themembrane electrode assembly 30, the coolant moves through thecoolant discharge passage 40 b, and the coolant is discharged through thecoolant outlet 80 b at theend plate 20 b (seeFIG. 1 ). - In the embodiment, as described above, when power generation is performed in the
fuel cell stack 10, in themembrane electrode assembly 30 of eachunit cell 12, the solidpolymer electrolyte membrane 42 is swelled by water produced in the power generation. At this time, since the produced water moves in the direction of gravity, the lower side of the solidpolymer electrolyte membrane 42 in the direction of gravity is swelled significantly. In particular, in the case where themembrane electrode assembly 30 has a longitudinally elongated shape, the difference in swelling in the direction of gravity becomes significantly large. - Thus, in each of the
unit cells 12, the thickness on the lower side in the direction of gravity (dimension in the direction indicated by the arrow A) becomes significantly larger than the thickness on the upper side in the direction of gravity. Therefore, a large dimensional difference in the stacking direction tends to occur, between the lower side and the upper side in a vertical direction in thestack body 14 as a whole. - In the first embodiment, the
casing 24 has the stackdeformation prevention structure 82. The stackdeformation prevention structure 82 is configured such that the elastic modulus of theside plate 60 d as the bottom plate is higher than the elastic modulus of theside plate 60 b of the top plate. Therefore, even if a large stress is applied to the lower side of thestack body 14 in the direction of gravity in comparison with the upper side of thestack body 14 in the direction of gravity, due to the difference of swelling in each of solidpolymer electrolyte membranes 42, the stress can be supported by the elastic modulus of theside plate 60 d. - Thus, with the simple structure, the change in the interval between the
end plates casing 24 are prevented suitably. -
FIG. 5 is a partial exploded perspective view showing afuel cell stack 90 according to a second embodiment of the present invention. The constituent elements that are identical to those of thefuel cell stack 10 according to the first embodiment are labeled with the same reference numeral, and description thereof will be omitted. Further, also in third to eighth embodiments as described later, the constituent elements that are identical to those of thefuel cell stack 10 according to the first embodiment are labeled with the same reference numeral, and description thereof will be omitted. - In the
fuel cell stack 90, theside plates casing 24 have stackdeformation prevention structure 92. Each of theside pates plate members deformation prevention structure 92 is configured such that the thickness of theplate member 94 a is larger than the thickness of theplate member 94 b. Therefore, even if a large stress is applied to the lower side of thestack body 14 in the direction of gravity in comparison with the upper side of thestack body 14 in the direction of gravity, due to the difference of swelling in each of the solidpolymer electrolyte membranes 42, the stress can be supported by the elastic modulus of theplate member 94 a. - Thus, in the second embodiment, the same advantages as in the case of the first embodiment are obtained. In the second embodiment, each of the
side plates plate members side plates stack body 14 in the direction of gravity to the lower side of thestack body 14 in the direction of gravity. -
FIG. 6 is a partial cross sectional view showing afuel cell stack 100 according to a third embodiment of the present invention. - In the
fuel cell stack 100, each of theunit cells 12 has stackdeformation prevention structure 102. The stackdeformation prevention structure 102 is configured such that elastic modulus ofends second seal members ends second seal members second seal members second seal members - In the third embodiment, elastic modulus of the
ends second seal members ends second seal members ends second seal members ends second seal members - Therefore, even if swelling of the lower side of each
unit cell 12 in the direction of gravity becomes large, the interval between the first andsecond metal separators second metal separators ends fuel cell stack 100 in the stacking direction is prevented effectively. Thus, the same advantages as in the case of the first embodiment are obtained. -
FIG. 7 is a side view showing aunit cell 12 of afuel cell stack 110 according to a fourth embodiment of the present invention. - In the
fuel cell stack 110, each of theunit cells 12 has stackdeformation prevention structure 112. The stackdeformation prevention structure 112 is configured such that the thickness (t1) on the lower side of the first andsecond metal separators second metal separators - In the fourth embodiment, in each of
unit cells 12, deformation in the stacking direction occurs easily on the lower side in the direction of gravity, in comparison with the upper side in the direction of gravity. It is because the thickness (t1) on the lower side of the first andsecond metal separators second metal separators polymer electrolyte membrane 42 of eachunit cell 12 in the direction of gravity is swelled to a great extent in comparison with the upper side of the solidpolymer electrolyte membrane 42 in the direction of gravity due to power generation, the first andsecond metal separators - Thus, swelling on the lower side of each solid
polymer electrolyte membrane 42 in the direction of gravity is absorbed easily by deformation of the first andsecond metal separators end plates fuel cell stack 110 as a whole. -
FIG. 8 is a side view showing aunit cell 12 of afuel cell stack 120 according to a fifth embodiment of the present invention. - In the
fuel cell stack 120, each of theunit cells 12 has stackdeformation prevention structure 122. The stackdeformation prevention structure 122 is configured such that the thickness (t3) on the lower side of the solidpolymer electrolyte membrane 42 of themembrane electrode assembly 30 in the direction of gravity is smaller than the thickness (t4) on the upper side of the solidpolymer electrolyte membrane 42 in the direction of gravity. - In the fifth embodiment, at the time of power generation in the
fuel cell stack 120, the solidpolymer electrolyte membrane 42 is swelled by absorption of water produced in the power generation. The thickness (t3) on the lower side of the solidpolymer electrolyte membrane 42 in the direction of gravity, i.e., the thickness on the side where the amount of the produced water is large is smaller than the thickness (t4) on the upper side of the solidpolymer electrolyte membrane 42 in the direction of gravity, i.e., the thickness on the side where the amount of the produced water is small. - Thus, by swelling, the thickness of the solid
polymer electrolyte membrane 42 becomes substantially uniform along the direction of gravity, and it becomes possible to inhibit application of the non-uniform load to thefuel cell stack 120. -
FIG. 9 is a partial cross sectional view showing afuel cell stack 130 according to a sixth embodiment of the present invention. - The
fuel cell stack 130 has stack deformation prevention structure 132. The stack deformation prevention structure 132 is configured such thattapered surfaces end plates tapered surfaces end plates end plates - In the sixth embodiment, in each of the
unit cells 12, when the lower side in the direction of gravity is swelled to a greater extent in comparison with the upper side in the direction of gravity, since the interval between theend plates end plates unit cells 12. Thus, when swelling occurs in eachunit cell 12 on the lower side in the direction of gravity, deformation of thefuel cell stack 130 is limited advantageously. - In the sixth embodiment, the
end plates surfaces plates terminal plates -
FIG. 10 is an exploded perspective view showing aunit cell 140 of a fuel cell stack according to a seventh embodiment of the present invention. - The
unit cell 140 has first andsecond metal separators membrane electrode assembly 30. The first andsecond metal separators first metal separator 142, a fuelgas flow field 48 is formed on a surface of thefirst metal separator 142 facing themembrane electrode assembly 30, and by corrugating thesecond metal separator 144, an oxygen-containinggas flow field 52 is formed on a surface of thesecond metal separator 144 facing themembrane electrode assembly 30. - The fuel
gas flow field 48 and the oxygen-containinggas flow field 52 has a cross sectional shape as shown inFIG. 11 on the upper side of thestack body 14 in the direction of gravity and a cross sectional shape as shown inFIG. 12 on the lower side of thestack body 14 in the direction of gravity. In the fuelgas flow field 48 and the oxygen-containinggas flow field 52, elastic modulus in the stacking direction, on the lower side of thestack body 14 in the direction of gravity is smaller than elastic modulus in the stacking direction, on the upper side of thestack body 14 in the direction of gravity. That is, the lower side of thestack body 14 can be deformed easily. - Thus, in the seventh embodiment, the
unit cell 140 is deformed easily in the stacking direction, on the lower side in the direction of gravity, in comparison with the upper side in the direction of gravity. Therefore, the same advantages as in the case of the fourth embodiment are obtained. For example, swelling on the lower side of the solidpolymer electrolyte membrane 42 in the direction of gravity is absorbed easily by deformation of the first andsecond metal separators -
FIG. 13 is an exploded perspective view showing aunit cell 150 of a fuel cell stack according to an eighth embodiment of the present invention. - The
unit cell 150 has first andsecond metal separators membrane electrode assembly 30. The first andsecond metal separators first metal separator 152, a fuelgas flow field 48 is formed on a surface of thefirst metal separator 152 facing themembrane electrode assembly 30, and by corrugating thesecond metal separator 154, an oxygen-containinggas flow field 52 is formed on a surface of thesecond metal separator 154 facing themembrane electrode assembly 30. - The fuel
gas flow field 48 and the oxygen-containinggas flow field 52 has a cross sectional shape as shown inFIG. 14 on the upper side of thestack body 14 in the direction of gravity and a cross sectional shape as shown inFIG. 15 on the lower side of thestack body 14 in the direction of gravity. In the fuelgas flow field 48 and the oxygen-containinggas flow field 52, elastic modulus in the stacking direction, on the lower side of thestack body 14 in the direction of gravity is smaller than elastic modulus in the stacking direction, on the upper side of thestack body 14 in the direction of gravity. That is, the lower side of thestack body 14 can be deformed easily. - Therefore, in the eighth embodiment, the same advantages as in the case of the seventh embodiment are obtained. For example, swelling in the direction of gravity, on the lower side of the solid
polymer electrolyte membrane 42 is absorbed easily by deformation of the first andsecond metal separators - While the invention has been particularly shown and described with reference to preferred embodiments, it will be understood that variations and modifications can be effected thereto by those skilled in the art without departing from the scope of the invention as defined by the appended claims.
Claims (9)
1. A fuel cell stack comprising:
a stack body formed by stacking a plurality of unit cells in a horizontal direction, a pair of end plates sandwiching the stack body, the unit cells each including an electrolyte electrode assembly and separators sandwiching the electrolyte electrode assembly, the electrolyte electrode assembly including a pair of electrodes and an electrolyte interposed between the electrodes; and
stack deformation prevention structure for limiting a change in an interval between the end plates on a lower side of the stack body in a direction of gravity to be not greater than a change in an interval between the end plates on an upper side of the stack body in the direction of gravity due to swelling on the lower side of the stack body in the direction of gravity.
2. A fuel cell stack according to claim 1 , wherein the stack deformation prevention structure is configured such that at least the thickness of the electrolyte or the separator on the lower side in the direction of gravity is smaller than the thickness of the electrolyte or the separator on the upper side in the direction of gravity.
3. A fuel cell stack according to claim 1 , wherein the stack deformation prevention structure is configured such that at least an interval between the end plates or between insulators adjacent to the end plates on the lower side in the direction of gravity is larger than an interval between the end plates or between the insulators adjacent to the end plates on the upper side in the direction of gravity.
4. A fuel cell stack according to claim 1 , wherein the stack deformation prevention structure is configured such that elastic modulus of a seal member of the stack body on the upper side in the direction of gravity is higher than elastic modulus of the seal member on the lower side in the direction of gravity.
5. A fuel cell stack according to claim 1 , further comprising a casing containing the stack body, wherein the casing includes a plurality of panel members provided around the stack body; and
the stack deformation prevention structure is configured such that elastic modulus of the panel member provided on the lower side in the direction of gravity is higher than elastic modulus of the panel member provided on the upper side in the direction of gravity.
6. A fuel cell stack according to claim 1 , further comprising a casing containing the stack body,
wherein the casing includes a plurality of panel members provided around the stack body; and
the stack deformation prevention structure is configured such that, in the panel members provided on lateral sides of the stack body, elastic modulus on the lower side in the direction of gravity is higher than elastic modulus on the upper side in the direction of gravity.
7. A fuel cell stack according to claim 6 , wherein the panel members provided on the lateral sides of the stack body each have two upper and lower plate members, and the thickness of the lower plate member is larger than the thickness of the upper plate member.
8. A fuel cell stack according to claim 1 , wherein the stack deformation prevention structure is configured such that elastic modulus in the stacking direction of the separators on the lower side in the direction of gravity is smaller than elastic modulus in the stacking direction of the separators on the upper side in the direction of gravity.
9. A fuel cell stack according to claim 1 , wherein each of the electrolyte electrode assembly and the separators has a longitudinally elongated shape.
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US (2) | US20090311571A1 (en) |
JP (1) | JP5254673B2 (en) |
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US20120058411A1 (en) * | 2010-09-02 | 2012-03-08 | Honda Motor Co., Ltd. | Fuel cell stack |
US20120251918A1 (en) * | 2009-07-27 | 2012-10-04 | Panasonic Corporation | Polymer fuel cell stack and polymer fuel cell separator pair |
US20130260275A1 (en) * | 2010-12-21 | 2013-10-03 | Nissan Motor Co., Ltd. | Fuel cell stack |
US20160072135A1 (en) * | 2013-05-16 | 2016-03-10 | Nissan Motor Co., Ltd. | Apparatus and method for producing fuel cell separator assembly |
US20160126563A1 (en) * | 2014-11-05 | 2016-05-05 | Toyota Jidosha Kabushiki Kaisha | Insulator and fuel cell device |
WO2016198337A1 (en) * | 2015-06-12 | 2016-12-15 | Elringklinger Ag | Electrochemical device and method for producing an electrochemical unit for an electrochemical device |
US10826104B2 (en) * | 2016-12-14 | 2020-11-03 | Airbus Operations Gmbh | Method for tailoring and integrating a fuel cell unit into a vehicle |
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US10833337B2 (en) | 2015-06-12 | 2020-11-10 | Elringklinger Ag | Electrochemical device and method for producing an electrochemical unit for an electrochemical device |
US10826104B2 (en) * | 2016-12-14 | 2020-11-03 | Airbus Operations Gmbh | Method for tailoring and integrating a fuel cell unit into a vehicle |
Also Published As
Publication number | Publication date |
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US20120321985A1 (en) | 2012-12-20 |
JP2009301889A (en) | 2009-12-24 |
JP5254673B2 (en) | 2013-08-07 |
US9190686B2 (en) | 2015-11-17 |
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