JP5509572B2 - Fuel cell and fuel cell manufacturing method - Google Patents

Description

  The present invention relates to a fuel cell and a method for manufacturing the fuel cell.

  A fuel cell is a device that generally obtains electric energy using hydrogen and oxygen as fuel. Since this fuel cell is excellent in terms of the environment and can realize high energy efficiency, it has been widely developed as a future energy supply system.

  The fuel cell includes, for example, an electrolyte membrane having proton conductivity, a cathode catalyst layer and an anode catalyst layer disposed along the electrolyte membrane, and a separator disposed on the opposite side of each catalyst layer from the electrolyte membrane. Prepare. In such a fuel cell, an oxidant gas is supplied to the cathode catalyst layer, and a fuel gas is supplied to the anode catalyst layer. Thereby, power generation is performed.

  Patent Document 1 discloses a fuel cell in which a current collector is embedded in a cathode catalyst layer and an anode catalyst layer. According to this fuel cell, the gas diffusion layer, the separator and the like need not have a current collecting function. Therefore, it is not necessary to bring the membrane-electrode assembly and the separator into contact with each other for current collection, so that the pitch of the reaction gas channel can be increased.

JP-A-2005-174872

  However, if a differential pressure is generated between the fuel gas and the oxidant gas flowing across the membrane-electrode assembly, the current collector and the membrane-electrode assembly may be deformed and sag toward the reaction gas flow path. Conceivable. In this case, it is considered that the pressure loss of the reaction gas channel increases. In addition, mechanical damage may occur in the membrane-electrode assembly due to stress caused by sagging. Furthermore, there is a possibility that stable contact between the membrane-electrode assembly and the current collector cannot be ensured.

  An object of this invention is to provide the fuel cell which can suppress a deformation | transformation of a collector and a membrane-electrode assembly, and its manufacturing method.

A fuel cell according to the present invention includes a membrane-electrode assembly including a solid polymer electrolyte membrane as an electrolyte, and is disposed on at least one surface of the membrane-electrode assembly and has gas permeability in the thickness direction and has at least a partial region. A current collector to which a tensile force is applied in a direction extending in the plane, a fixing means for fixing the current collector in a state in which a tensile force is applied to the current collector, and a tension applied to the current collector Adjusting means for adjusting the force, the tensile force has a force component from the current collector to the membrane-electrode assembly, and the adjusting means determines the tensile force applied to the current collector to a predetermined value. The predetermined range is expressed by σ>F> (2-V · L · sin θ) · 2E. Where σ is the yield load of the current collector, F is the tensile force, V is the amount of deflection that stabilizes the contact resistance between the membrane-electrode assembly and the current collector , and L is the current collector length. Is the angle formed by the fixed portion of the current collector and the tensile force, and E is the Young's modulus of the current collector. In the fuel cell according to the present invention, since the tensile force is applied to the current collector, deformation of the current collector and the membrane-electrode assembly can be suppressed.

The separator may be provided on the opposite side of the current collector from the membrane-electrode assembly, and the separator may have a crimped portion in which the current collector is crimped to the separator.

  The current collector has a rectangular shape, and the tensile force may be applied in a direction in which the two long sides of the current collector are separated from each other. In this case, the tensile stress can be reduced with a predetermined tensile force applied to the current collector. Thereby, the creep resistance of the current collector can be improved. The current collector may have a substantially circular shape, and the tensile force may be applied radially outward in a substantially circular shape. In this case, stress concentration in the current collector can be suppressed.

Detection means for detecting a tensile force required for the current collector may be provided, and the adjustment means may adjust the tensile force applied to the current collector to the tensile force detected by the detection means. The detection means may detect a tensile force necessary for the current collector based on the resistance of the membrane-electrode assembly or the pressure loss of the reaction gas flow path of the fuel cell. A terminal for taking out the generated power in the membrane-electrode assembly may be provided on the outer periphery of the current collector. Another fuel cell according to the present invention is disposed on at least one surface of a membrane-electrode assembly including a solid polymer electrolyte membrane as an electrolyte and the membrane-electrode assembly, and has gas permeability in the thickness direction. And a current collector to which a tensile force is applied in the direction of extension in the plane of the part region, and the tensile force is represented by σ>F> (2-V · L · sin θ) · 2E It is characterized by. Where σ is the yield load of the current collector, F is the tensile force, V is the amount of deflection that stabilizes the contact resistance between the membrane-electrode assembly and the current collector , and L is the current collector length. Yes, θ is the angle formed by the fixed portion of the current collector and the tensile force, and E is the Young's modulus of the current collector.

The method of manufacturing a fuel cell according to the present invention includes a step of heating a current-permeable current collector in a thickness direction, a step of fixing at least two points of the heated current collector, and fixing at least two points. A step of cooling the current collector, and a step of laminating the current collector as an electrolyte on at least one surface of a membrane-electrode assembly including a solid polymer electrolyte membrane, and a tensile force applied to the current collector σ>F> (2−V · L · sin θ) · 2E. Where σ is the yield load of the current collector, F is the tensile force, V is the amount of deflection that stabilizes the contact resistance between the membrane-electrode assembly and the current collector , and L is the current collector length. Yes, θ is the angle formed by the fixed portion of the current collector and the tensile force, and E is the Young's modulus of the current collector. In the fuel cell manufacturing method according to the present invention, the current collector can be expanded by heating, and a tensile force can be applied to the current collector by cooling. Thereby, deformation of the current collector and the membrane-electrode assembly can be suppressed.

Another method for manufacturing a fuel cell according to the present invention includes a step of applying a tensile force in a direction in which a current-permeable current collector in a thickness direction extends in a plane in at least a part of the current collector, A step of fixing the current collector in a state where a tensile force is applied, and a step of laminating the current collector on at least one surface of a membrane-electrode assembly including a solid polymer electrolyte membrane as an electrolyte. The tensile force applied to σ>F> (2−V · L · sin θ) · 2E. Where σ is the yield load of the current collector, F is the tensile force, V is the amount of deflection that stabilizes the contact resistance between the membrane-electrode assembly and the current collector , and L is the current collector length. Yes, θ is the angle formed by the fixed portion of the current collector and the tensile force, and E is the Young's modulus of the current collector. In another method for producing a fuel cell according to the present invention, a tensile force can be applied to the current collector. Thereby, deformation of the membrane-electrode assembly and the current collector can be suppressed.

  According to the present invention, deformation of the current collector and the membrane-electrode assembly can be suppressed.

  Hereinafter, the best mode for carrying out the present invention will be described.

  FIG. 1 is a schematic cross-sectional view of a fuel cell 100 according to the first embodiment. As shown in FIG. 1, the fuel cell 100 has a structure in which a current collector 20 and a separator 30 are stacked on one surface of a membrane-electrode assembly 10 and a current collector 40 and a separator 50 are stacked on the other surface.

  The membrane-electrode assembly 10 has a structure in which the anode catalyst layer 12 is joined to the current collector 20 side of the electrolyte membrane 11 and the cathode catalyst layer 13 is joined to the current collector 40 side of the electrolyte membrane 11. For example, a solid polymer electrolyte having proton conductivity can be used as the electrolyte membrane 11. The anode catalyst layer 12 and the cathode catalyst layer 13 are made of a conductive material containing a catalyst. The catalyst of the anode catalyst layer 12 promotes protonation of hydrogen. The catalyst of the cathode catalyst layer 13 promotes the reaction between protons and oxygen. As the anode catalyst layer 12 and the cathode catalyst layer 13, for example, platinum-supported carbon can be used.

  The current collector 20 is disposed along the anode catalyst layer 12. At least a part of the current collector 20 may be embedded in the anode catalyst layer 12. A terminal 21 for taking out electric power from the fuel cell 100 without using the separator 30 is provided on the outer peripheral portion of the current collector 20. In the present embodiment, the terminal 21 is provided outside the separator 30.

  The current collector 40 is disposed along the cathode catalyst layer 13. At least a part of the current collector 40 may be embedded in the cathode catalyst layer 13. A terminal 41 for taking out electric power from the fuel cell 100 without using the separator 50 is provided on the outer periphery of the current collector 40. In the present embodiment, the terminal 41 is provided outside the separator 50.

  The current collectors 20 and 40 are made of a conductive material having gas permeability in the thickness direction. For example, the current collectors 20 and 40 are made of a porous conductive material. As the current collectors 20 and 40, for example, a metal mesh, a metal foam sintered body, an expanded metal, a carbon fiber, a carbon sintered body, or the like is used. FIG. 2 shows an example of expanded metal.

  Fig.2 (a)-FIG.2 (c) are typical perspective views of an expanded metal. As shown in FIGS. 2A to 2C, the expanded metal includes a plurality of recesses 22 that protrude from the membrane-electrode assembly 10 and come into contact with the membrane-electrode assembly 10. An opening is provided in the convex portion 23 that is continuously adjacent to the concave portion 22 and protrudes to the opposite side of the membrane-electrode assembly 10. The reaction gas is supplied to the membrane-electrode assembly 10 through this opening.

  The concave portions 22 and the convex portions 23 are regularly arranged in rows and columns, for example. When the positions of the convex portions 23 are different between adjacent rows, the reaction gas can be supplied to the entire membrane-electrode assembly 10. For example, the concave portions 22 and the convex portions 23 are arranged at a pitch of about 0.5 mm. The expanded metal can be processed using a mold in which irregularities are repeatedly formed.

  The bottom surface of the recess 22 is inclined with respect to the membrane-electrode assembly 10. Accordingly, the entire bottom surface of the recess 22 is not in contact with the membrane-electrode assembly 10, but a part thereof is in contact with the membrane-electrode assembly 10. This makes it easier to supply the reaction gas supplied to the expanded metal to the membrane-electrode assembly 10. The bottom surface of the recess 22 has, for example, a rectangular shape.

  Separator 30,50 has a contact part which protrudes and contacts with membrane-electrode assembly 10 in an outer peripheral part. Thereby, a space 31 for fuel gas flow is defined between the separator 30 and the membrane-electrode assembly 10. A space 51 for flowing an oxidant gas is defined between the separator 50 and the membrane-electrode assembly 10. In addition, the separators 30 and 50 may have a contact portion that contacts the membrane-electrode assembly 10 in addition to the outer peripheral portion as long as the flow of the reaction gas is not hindered. However, in consideration of the diffusibility of the reaction gas into the membrane-electrode assembly 10, it is preferable that a reaction gas flow space is formed over the entire surface or almost the entire surface of the membrane-electrode assembly 10.

  A fuel gas supply means 110 such as a hydrogen tank is connected to the space 31 for flowing the fuel gas. An oxidant gas supply means 120 such as an air pump is connected to the oxidant gas flow space 51.

  Next, an outline of the operation of the fuel cell 100 will be described. The fuel gas is supplied to the space 31 by the fuel gas supply means 110. The fuel gas supplied to the space 31 passes through the current collector 20 and diffuses into the anode catalyst layer 12. In the anode catalyst layer 12, hydrogen in the fuel gas is separated into protons and electrons. Protons are conducted through the electrolyte membrane 11 and reach the cathode catalyst layer 13. The electrons are collected by the current collector 20 and supplied to the load 130 via the terminal 21, and then reach the current collector 40.

The oxidant gas is supplied to the space 51 by the oxidant gas supply means 120. The oxidant gas supplied to the space 51 passes through the current collector 40 and diffuses into the cathode catalyst layer 13. In the cathode catalyst layer 13, water is generated from oxygen in the oxidant gas, protons conducted through the electrolyte membrane 11, and electrons supplied from the load 130 to the terminal 41. Through the above process, the fuel cell 100 generates power.

  In the fuel cell 100 according to the present embodiment, the current is collected through the terminals 21 and 41, so that the separators 30 and 50 do not require conductivity. Accordingly, as the separators 30 and 50, materials that are lighter and lower in cost than metals may be used. For example, by using a resin, the separators 30 and 50 can be reduced in weight and cost, and the separators 30 and 50 can have corrosion resistance.

  Further, since the contact between the separators 30 and 50 for current collection and the membrane-electrode assembly 10 is not necessary, the electrical connection between the separators 30 and 50 and the membrane-electrode assembly 10 such as a groove channel is made. A contact part is unnecessary. Thereby, the pressure loss when the reaction gas flows through the reaction gas flow path is reduced. As a result, the power generation performance of the fuel cell 100 is improved.

  In the fuel cell 100, a differential pressure may occur between the fuel gas supplied to the space portion 31 and the oxidant gas supplied to the space portion 51. For example, when the fuel cell pressure is temporarily increased at the time of starting the fuel cell 100 in order to reduce the impurity concentration in the space 31, the fuel gas pressure> the oxidant gas pressure. Further, when the back pressure of the oxidant gas is temporarily increased in order to suppress the removal of generated water from the cathode catalyst layer 13 during a high load operation, the oxidant gas pressure> the fuel gas pressure. When the differential pressure is generated as described above, the membrane-electrode assembly 10 and the current collectors 20 and 40 may be deformed and bent. Therefore, in this embodiment, by applying a tensile force to the current collectors 20 and 40, deformation of the membrane-electrode assembly 10 and the current collectors 20 and 40 is suppressed.

  FIG. 3 is a diagram for explaining the tensile force applied to the current collectors 20 and 40. As shown in FIG. 3A, a tensile force is applied to the current collectors 20 and 40 in a direction extending in the surface direction. For example, when the current collectors 20 and 40 have a rectangular shape, a tensile force may be applied to each corner of the current collectors 20 and 40 as shown in FIG. Further, as shown in FIG. 3C, a tensile force may be applied to each side of the current collectors 20 and 40. 3B and 3C are plan views of the current collectors 20 and 40. FIG.

  By applying a tensile force to the current collectors 20 and 40, deformation of the current collectors 20 and 40 is suppressed. In this case, floating of the current collectors 20 and 40 toward the separator can be suppressed. Thereby, deformation of the membrane-electrode assembly 10 is also suppressed. As a result, the adhesion between the membrane-electrode assembly 10 and the current collectors 20 and 40 is improved. Moreover, the pressure loss fall of the space parts 31 and 51 is suppressed. Furthermore, mechanical damage to the membrane-electrode assembly 10 can be suppressed. In addition, if the tensile force is added to the direction extended in the surface of the at least one part area | region of the collectors 20 and 40, the deformation | transformation of the collectors 20 and 40 can be suppressed.

  FIG. 4 is a diagram for explaining a procedure for applying a tensile force to the current collector 20. As shown in FIG. 4A, the pin 24 may be passed through the current collector 20 and fixed to the recess of the separator 30 while applying a tensile force to the current collector 20. In this case, the pin 24 has a function as a fixing means.

  Further, as shown in FIG. 4B, the end of the separator 30 and the end of the current collector 20 are both crimped while applying a tensile force to the current collector 20. As a result, the current collector 20 can be fixed to the separator 30 with a tensile force applied.

  Moreover, as shown in FIG.4 (c), you may fix to the separator 30 by adhesion | attachment, welding, diffusion bonding, etc., adding the tensile force to the electrical power collector 20. FIG.

  Further, as shown in FIG. 4D, the current collector 20 may be cooled by being fixed to the separator 30 by bonding or the like in a state where the current collector 20 is expanded by heating. In this case, a tensile force is applied to the current collector 20 by heat shrinkage.

  Further, as shown in FIG. 4E, a protrusion 25 may be provided outside the contact portion of the outer peripheral portion of the separator 30, and a tensile force may be applied to the current collector 20 to be hooked on the protrusion 25. In this case, the current collector 20 can be fixed to the separator 30 with a tensile force applied.

  Note that the current collector 40 may also be fixed to the separator 50 by applying a tensile force according to the same procedure as in FIGS. 4A to 4E.

  FIG. 5 is a diagram for explaining the pulling direction when the current collectors 20 and 40 have a rectangular shape. Here, the tensile stress is derived from tensile force / cross-sectional area = tensile force / (length of side × thickness). Therefore, even if the tensile force is the same, the tensile stress changes according to the length of the side.

  Here, the tensile force required to suppress the deformation of the current collectors 20 and 40 is the same regardless of the direction in which they are applied. However, the tensile stress varies depending on the direction in which the tensile force is applied. If the tensile stress is large, the creep resistance of the current collectors 20 and 40 when used for a long time may be lowered. Therefore, when the current collectors 20 and 40 have a rectangular shape, a tensile force is applied to the long side. In this case, the tensile stress applied to the current collectors 20 and 40 can be reduced. Thereby, the creep resistance of the current collectors 20 and 40 can be improved.

  The current collectors 20 and 40 may have a shape other than a rectangular shape. For example, the current collectors 20 and 40 may have a substantially circular shape as shown in FIG. In this case, the tensile force is preferably applied outward in the radial direction of the current collectors 20 and 40. This is because the stress concentration in the current collectors 20 and 40 can be suppressed. Moreover, it is more preferable that the tensile force is applied in a plurality of radially outward directions at equal intervals on the outer circumferences of the current collectors 20 and 40. This is because the stress concentration can be further suppressed.

  FIG. 7 is a diagram for explaining the fixing means when the current collectors 20 and 40 have a substantially circular shape. FIG. 7A and FIG. 7B are a cross-sectional view and a plan view of the fuel cell 100 when the current collectors 20 and 40 have a substantially circular shape. As shown in FIGS. 7A and 7B, a fixing member 90 is disposed along the outer peripheral edge of the membrane-electrode assembly 10, and a predetermined interval is provided between the fixing member 90 (for example, etc.). A fixed pin 26 is arranged (at intervals). A tensile force is applied outwardly in the radial direction to the current collectors 20 and 40 and hooked on the fixing pin 26. Thereby, stress concentration in the current collectors 20 and 40 can be suppressed.

  FIG. 8 is a diagram for explaining another example of the fixing means when the current collectors 20 and 40 have a substantially circular shape. FIGS. 8A and 8B are a cross-sectional view and a plan view of another example of the fuel cell 100 when the current collectors 20 and 40 have a substantially circular shape. As shown in FIGS. 8A and 8B, the fixing pins 27 are arranged at predetermined intervals (for example, at equal intervals) along the outside of the contact portions of the separators 30 and 50. A tensile force is applied to the current collectors 20, 40 outward in the radial direction and hooked on the fixing pin 27. Thereby, stress concentration in the current collectors 20 and 40 can be suppressed.

  FIG. 9 is a diagram for explaining the tensile force applied to the current collectors 20 and 40. FIG. 9A is a diagram showing the current collectors 20 and 40 when the deflection is caused by the differential pressure between the fuel gas and the oxidant gas. In FIG. 9A, “F” is a tensile force applied to the current collectors 20 and 40, “W” is a load applied to the current collectors 20 and 40 in the direction perpendicular to the surface, and “L” "Is the span (current collector length) of the current collectors 20 and 40, and" Vmax "is the maximum deflection amount of the current collectors 20 and 40.

FIG. 9B is a diagram showing the relationship between the contact resistance between the current collectors 20 and 40 and the membrane-electrode assembly 10 and the amount of deflection of the current collectors 20 and 40. In FIG. 9B, the horizontal axis indicates the amount of deflection of the current collectors 20 and 40, and the vertical axis indicates the contact resistance between the current collectors 20 and 40 and the membrane-electrode assembly 10. As shown in FIG. 9B, the contact resistance hardly changes up to a predetermined deflection amount, but starts to increase when the predetermined deflection amount is exceeded. The amount of deflection in this case is V ₀ . That is, the deflection amount V ₀ is the maximum deflection amount that can stabilize the contact resistance. From the viewpoint of performance required for the fuel cell 100, the contact resistance is allowed up to a predetermined value. The allowable deflection amount corresponding to the contact resistance is in this case a V _1.

The tensile force applied to the current collectors 20 and 40 is obtained as shown in the following formula (1). In Equation (1), “E” is the Young's modulus of the current collectors 20 and 40, “ε” is the strain amount of the current collectors 20 and 40, and “L ′” is the deformed current collector. The current collector length is 20, 40.
F = E · ε = E · ΔL / L = E · (L−L ′) / L
= E · (1-2Vmax / sinθ) / L (1)

Here, when the maximum deflection amount Vmax is allowed to deflection of V _1, the following formula (2) is satisfied.
V ₁ > Vmax (2)

The following equation (3) is derived from the equations (1) and (2). Further, the minimum tensile force Fmin required for the current collectors 20 and 40 is derived from the following equation (4).
V ₁ > (E−F) · L · sin θ / 2E (3)
4E>Fmin> (2-V ₁ · L · sin θ) · 2E (4)

Further, when the yield load of the current collectors 20 and 40 is σ and the maximum value of the tensile force applied to the current collectors 20 and 40 is Fmax, the following formula (5) is established.
σ> Fmax (5)

From the above, the tensile force F applied to the current collectors 20 and 40 is a value in the range of the following formula (6).
σ>F> (2-V ₁ · L · sin θ) · 2E (6)

In each of the above equations, if the maximum deflection amount Vmax is allowed up to the deflection amount V ₀ , V ₁ is replaced with V ₀ in each equation.

  Note that the tensile force applied to the current collectors 20, 40 may have not only the surface direction components of the current collectors 20, 40 but also the stacking direction components of each part in the fuel cell 100. For example, as shown in FIG. 10A, the tensile force applied to the current collectors 20 and 40 preferably has a component from the current collectors 20 and 40 toward the membrane-electrode assembly 10. . This is because the adhesion between the current collectors 20 and 40 and the membrane-electrode assembly 10 is improved. As shown in FIG. 10B, similarly, when a plurality of fuel cells 100 are stacked, the tensile force applied to the current collectors 20, 40 is applied from the current collectors 20, 40 to the membrane-electrode joint. It is preferable to have a component toward the body 10.

  Next, the fuel cell 100a according to Example 2 will be described. The fuel cell 100a includes an adjusting unit for manually adjusting the tensile force of the current collector 20. FIG. 11 is a schematic diagram of the adjusting means 60 for adjusting the tensile force. As shown in FIG. 11A, the adjusting means 60 has a screw structure in which a wire or the like connected to the outer peripheral end of the current collector 20 is wound. The tensile force can be increased by tightening the screw of the adjusting means 60, and the tensile force can be decreased by loosening the screw. Thereby, the tensile force of the current collector 20 can be adjusted to an appropriate value. The adjusting means 60 may be connected to the current collector 40.

  As shown in FIG. 11B, when a fuel cell stack is configured by stacking a plurality of fuel cells 100a, the current collector of each fuel cell 100a is provided by providing the adjustment means 60 in each fuel cell 100a. The tensile force of 20, 40 can be adjusted.

  Also, as shown in FIG. 11C, a common bus bar 61 is provided for each fuel cell 100a, and the outer peripheral end of the current collector of each fuel cell 100a and the bus bar 61 are connected by a wire or the like. Good. In this case, a tensile force can be applied to each current collector by applying a tensile force to the bus bar 61. For example, the tensile force applied to the bus bar 61 can be adjusted by fixing the adjusting means 62 having a screw structure to the case of the fuel cell stack.

  In this embodiment, the adjusting means 60, 62 are provided on one side of the current collectors 20, 40, but may be provided on both sides. By providing the adjustment means 60 in each fuel cell 100a as shown in FIGS. 11 (a) and 11 (b), the tensile force can be individually adjusted for each fuel cell 100a. On the other hand, as shown in FIG. 11 (c), by providing the common adjustment means 62 for each fuel cell 100a, it is possible to adjust the tensile force of a plurality of current collectors at a time.

  Next, the fuel cell system 200 according to Example 3 will be described. FIG. 12 is a schematic diagram showing the overall configuration of the fuel cell system 200. As shown in FIG. 12, the fuel cell system 200 includes a fuel cell stack 201, pressure valves 202 to 205, a resistance sensor 206, and control means 207. The fuel cell stack 201 has a stack structure in which a plurality of fuel cells 100 according to the first embodiment are stacked. The fuel cell stack 201 is provided with a bus bar 61 connected in common with the current collectors 20 and 40 of each fuel cell 100. A screw structure adjusting means 62 is fixed to the case of the fuel cell stack 201. The adjusting means 62 has a built-in motor 63. The tensile force applied to the bus bar 61 is adjusted according to the rotation of the motor 63.

  The pressure valve 202 is a pressure control valve that controls the pressure of the fuel gas supplied to the fuel cell stack 201. The pressure valve 203 is a pressure control valve that controls the off-gas pressure of the fuel gas discharged from the fuel cell stack 201. The pressure valve 204 is a pressure control valve that controls the pressure of the oxidant gas supplied to the fuel cell stack 201. The pressure valve 205 is a pressure control valve that controls the off-gas pressure of the oxidant gas discharged from the fuel cell stack 201.

  The resistance sensor 206 is a sensor for detecting the resistance of the fuel cell stack 201. The control means 207 includes a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory) and the like. The control means 207 detects the pressure loss of the fuel gas channel and the pressure loss of the oxidant gas channel based on the control pressure of the pressure valves 202 to 205. Further, the control unit 207 detects the resistance of the fuel cell stack 201 based on the detection result of the resistance sensor 206. The control means 207 controls the motor 63 based on these detection results.

  When the tensile force applied to the current collectors 20 and 40 is reduced, the current collectors 20 and 40 are deformed. Thereby, the pressure loss of the space parts 31 and 51 increases. Therefore, based on the increase in pressure loss, it can be determined whether or not the tensile force applied to the current collectors 20 and 40 is insufficient. Further, when the current collectors 20 and 40 are deformed, the contact resistance between the current collectors 20 and 40 and the membrane-electrode assembly 10 increases, and the resistance of the fuel cell stack 201 increases. Therefore, based on the increase in resistance of the fuel cell stack 201, it can be determined whether or not the tensile force applied to the current collectors 20 and 40 is insufficient. Therefore, in this embodiment, the pressure valves 202 to 205 and the resistance sensor 206 function as detection means for detecting the tensile force required for the current collector.

  FIG. 13 is a diagram showing an example of the relationship between the pressure loss and resistance allowed for the fuel cell stack 201. As shown in FIG. 13, pressure loss and resistance are allowed in a relatively low range. The control means 207 may determine whether or not the tensile force is insufficient based on FIG.

  FIG. 14 is a diagram illustrating an example of a flowchart executed by the control unit 207. As shown in FIG. 14, the control means 207 detects pressure loss and resistance (step S1). Next, the control means 207 determines whether or not the pressure loss and resistance detected in step S1 are within an allowable range (step S2). When it is determined in step S2 that the pressure loss and the resistance are within the allowable ranges, the control unit 207 executes step S1 again.

  If it is not determined in step S2 that the pressure loss and the resistance are within the allowable ranges, the control unit 207 acquires the tensile force required for the current collectors 20 and 40 (step S3). In this case, the tensile force may be acquired based on a table stored in advance, or the tensile force may be calculated according to the above formulas (1) to (6). Next, the control means 207 controls the motor 63 to adjust the tensile force of the current collectors 20 and 40 to the tensile force acquired in step S3 (step S4). Thereafter, the control unit 207 ends the execution of the flowchart.

  According to the flowchart of FIG. 14, the tensile force applied to the current collectors 20 and 40 can be automatically controlled to a desired range of values. Thereby, a change with time can be avoided and deformation of the current collectors 20 and 40 can be suppressed. As a result, an increase in pressure loss in the reaction gas channel can be suppressed, mechanical damage of the membrane-electrode assembly 10 can be suppressed, and the stability of the membrane-electrode assembly 10 and the current collectors 20 and 40 can be stabilized. Contact can be maintained.

  In addition, in each said Example, although tensile force was added to both the collector 20 and the collector 40, you may add to any one. Instead of the separators 30 and 50, a separator having a groove channel formed on the surface on the membrane-electrode assembly 10 side may be used. Even in this case, deformation of the current collector can be suppressed in each groove portion of the groove flow path by applying a tensile force to the current collector.

1 is a schematic cross-sectional view of a fuel cell according to Example 1. FIG. It is a typical perspective view of an expanded metal. It is a figure for demonstrating the tensile force added to the electrical power collector. It is a figure for demonstrating the procedure which adds tensile force to a collector. It is a figure for demonstrating the pulling direction in case a collector has rectangular shape. It is a figure for demonstrating the pulling direction in case a collector has a substantially circular shape. It is a figure for demonstrating a fixing means in case a collector has a substantially circular shape. It is a figure for demonstrating the other example of a fixing means in case a collector has a substantially circular shape. It is a figure for demonstrating the tensile force added to a collector. It is a figure for demonstrating the lamination direction component of tensile force. It is a schematic diagram of the adjustment means for adjusting tensile force. FIG. 6 is a schematic diagram illustrating an overall configuration of a fuel cell system according to Example 3. It is a figure which shows an example of the relationship between the pressure loss and resistance which are accept | permitted by a fuel cell stack. It is a figure which shows an example of the flowchart performed by a control means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Membrane-electrode assembly 11 Electrolyte membrane 12 Anode catalyst layer 13 Cathode catalyst layer 20 Current collector 21 Terminal 30 Separator 40 Current collector 41 Terminal 50 Separator 100 Fuel cell 110 Fuel gas supply means 120 Oxidant gas supply means

Claims (10)

A membrane-electrode assembly including a solid polymer electrolyte membrane as an electrolyte;
A current collector disposed on at least one surface of the membrane-electrode assembly, having gas permeability in the thickness direction, and having a tensile force applied in a direction extending in the plane of at least a part of the region;
Fixing means for fixing the current collector in a state where the tensile force is applied to the current collector;
Adjusting means for adjusting the tensile force applied to the current collector,
The tensile force has a force component from the current collector to the membrane-electrode assembly,
The adjusting means adjusts the tensile force applied to the current collector to a predetermined range,
The predetermined range is expressed by σ>F> (2-V · L · sin θ) · 2E.
Where σ is the yield load of the current collector, F is the tensile force, V is the amount of deflection that stabilizes the contact resistance between the membrane-electrode assembly and the current collector , and L is The current collector length, θ is an angle formed by a fixed portion of the current collector and the tensile force, and E is a Young's modulus of the current collector. A separator disposed on the side of the current collector opposite to the membrane-electrode assembly,
2. The fuel cell according to claim 1, wherein the separator includes a crimped portion in which the current collector is crimped to the separator. The current collector has a rectangular shape,
The fuel cell according to claim 1, wherein the tensile force is applied in a direction in which two long sides of the current collector are separated from each other. The current collector has a substantially circular shape,
The fuel cell according to claim 1, wherein the tensile force is applied outward in the radial direction of the substantially circular shape. Comprising detection means for detecting a tensile force required for the current collector;
The fuel cell according to any one of claims 1 to 4, wherein the adjusting means adjusts a tensile force applied to the current collector to a tensile force detected by the detecting means.   The said detection means detects the tensile force required for the said collector based on the resistance of the said membrane-electrode assembly, or the pressure loss of the reaction gas flow path of the said fuel cell. Fuel cell.   The fuel cell according to any one of claims 1 to 6, wherein a terminal for taking out generated electric power in the membrane-electrode assembly is provided on an outer peripheral portion of the current collector. A membrane-electrode assembly including a solid polymer electrolyte membrane as an electrolyte;
A current collector disposed on at least one surface of the membrane-electrode assembly, having gas permeability in the thickness direction, and having a tensile force applied in a direction extending in a plane of at least a part of the region. ,
The tensile force is expressed by σ>F> (2-V · L · sin θ) · 2E.
Where σ is the yield load of the current collector, F is the tensile force, V is the amount of deflection that stabilizes the contact resistance between the membrane-electrode assembly and the current collector , and L is The current collector length, θ is an angle formed by a fixed portion of the current collector and the tensile force, and E is a Young's modulus of the current collector. Heating a current-permeable current collector in the thickness direction;
Fixing at least two points of the heated current collector;
Cooling the current collector fixed at least at two points;
Laminating the current collector on at least one surface of a membrane-electrode assembly including a solid polymer electrolyte membrane as an electrolyte, and
A method for manufacturing a fuel cell, wherein a tensile force applied to the current collector is σ>F> (2-V · L · sin θ) · 2E.
Where σ is the yield load of the current collector, F is the tensile force, V is the amount of deflection that stabilizes the contact resistance between the membrane-electrode assembly and the current collector , and L is The current collector length, θ is an angle formed by a fixed portion of the current collector and the tensile force, and E is a Young's modulus of the current collector. A step of applying a tensile force in a direction in which the current-permeable current collector in the thickness direction extends in a plane in at least a part of the region;
Fixing the current collector with a tensile force applied to the current collector;
Laminating the current collector on at least one surface of a membrane-electrode assembly including a solid polymer electrolyte membrane as an electrolyte, and
A method for manufacturing a fuel cell, wherein a tensile force applied to the current collector is σ>F> (2-V · L · sin θ) · 2E.
Where σ is the yield load of the current collector, F is the tensile force, V is the amount of deflection that stabilizes the contact resistance between the membrane-electrode assembly and the current collector , and L is The current collector length, θ is an angle formed by a fixed portion of the current collector and the tensile force, and E is a Young's modulus of the current collector.

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