JP2015022856A - Impedance measuring device for fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an impedance measuring device for a fuel cell, capable of easily and accurately measuring impedance at an electrode reaction surface of a fuel cell, with a compact and simple constitution.SOLUTION: An impedance measuring device 10 for a fuel cell includes: a first electrode part 50 disposed on an anode electrode 40 side; and a second electrode part 52 disposed on a cathode electrode 38 side to face the first electrode part 50. The first electrode part 50 is disposed outside an electrode catalyst layer 40a, and the second electrode part 52 is disposed outside an electrode catalyst layer 38a. The first electrode part 50 is provided in a first sheet member 54, while the second electrode part 52 is provided in a second sheet member 56.

Description

  The present invention relates to an impedance measuring device for a fuel cell incorporated in a fuel cell in which an electrolyte / electrode structure provided with electrodes on both sides of an electrolyte and a separator are laminated.

  For example, a polymer electrolyte fuel cell employs an electrolyte membrane (electrolyte) made of a polymer ion exchange membrane. This fuel cell is constructed by sandwiching an electrolyte membrane / electrode structure (MEA) having an anode electrode on one side of the electrolyte membrane and a cathode electrode on the other side of the electrolyte membrane with a separator. ing.

  In a fuel cell, it is necessary to accurately grasp the power generation status in order to reliably perform desired power generation. For example, the electrolyte membrane must be moistened to a desired wet state in order to maintain the power generation performance. When the electrolyte membrane is in a dry state, the power generation performance is degraded.

  On the other hand, when the amount of water generated by power generation is large and the water becomes excessive, flooding is likely to occur. For this reason, the channel | path etc. which distribute | circulate reaction gas may be clogged, and there exists a possibility that electric power generation performance may fall. In addition, performance degradation may occur due to a shortage of fuel gas.

  Thus, for example, a fuel cell disclosed in Patent Document 1 is known. In this fuel cell, the separator is provided in the region of the electrode reaction surface, and a plurality of measurement electrode members whose one surface is in contact with the electrolyte / electrode structure and the measurement electrode members are insulated from each other. An insulating resin member that is separated and held in a state and a flexible substrate that is individually electrically connected to the other surface of each measurement electrode member are provided.

  In Patent Document 1, since the electrode reaction surface region of the electrolyte / electrode structure is divided into a plurality of regions and a plurality of measurement electrode members are provided, the impedance distribution of each region in the electrode reaction surface can be easily and It can be measured accurately.

JP2013-4496A

  The present invention has been made in connection with this type of technology, and has a compact and simple configuration and can easily and accurately measure the impedance of the electrode reaction surface of the fuel cell. The purpose is to provide.

  The present invention relates to an impedance measuring device for a fuel cell incorporated in a fuel cell in which an electrolyte / electrode structure provided with electrodes on both sides of an electrolyte and a separator are laminated.

  In this fuel cell impedance measuring device, the first electrode portion disposed on one electrode side of the electrolyte / electrode structure and the first electrode portion on the other electrode side of the electrolyte / electrode structure are opposed to the first electrode portion. The second electrode portion is disposed, the first electrode portion is provided at one end portion, the other end portion extends outward from the electrolyte / electrode structure, and the one end portion includes the first sheet member. A second sheet member provided with a second electrode portion and the other end portion extending outward of the electrolyte / electrode structure. An alternating current is applied to the electrolyte / electrode structure from the outside.

  Further, in this fuel cell impedance measuring apparatus, at least the resistor and the third electrode portion provided adjacent to the first electrode portion, the resistor and the third electrode portion provided at one end portion, and the other end It is preferable that the portion includes a third sheet member that extends outward from the electrolyte / electrode structure. The resistor may include not only DC resistance but also AC resistance.

  Further, in the fuel cell impedance measuring apparatus, it is preferable that the other end portions of the first sheet member, the second sheet member, and the third sheet member are integrated with each other.

  Furthermore, in this fuel cell impedance measuring apparatus, it is preferable that the first electrode portion and the second electrode portion are in contact with the outside of each catalyst layer or the outside of each diffusion layer constituting the electrode.

  According to the present invention, the first electrode portion and the second electrode portion are disposed so as to face each other corresponding to the local site in the electrode reaction surface of the electrolyte / electrode structure. The first electrode portion is provided at one end of the first sheet member, while the second electrode portion is provided at one end of the second sheet member.

  For this reason, the impedance of the local site | part in an electrode reaction surface can be measured easily and correctly. In addition, the configuration can be simplified at a time, and it can be manufactured economically. This makes it possible to easily and accurately measure the impedance of the electrode reaction surface of the fuel cell with a compact and simple configuration.

1 is a schematic side view of a fuel cell stack in which a fuel cell impedance measuring apparatus according to a first embodiment of the present invention is incorporated. It is a principal part disassembled perspective view of the fuel cell for a measurement which comprises the said fuel cell stack. FIG. 3 is a cross-sectional view of the fuel cell taken along line III-III in FIG. 2. It is a partial perspective explanatory view of the fuel cell impedance measuring device. It is principal part cross-sectional explanatory drawing of the electrolyte membrane and electrode structure in which the impedance measuring apparatus for fuel cells which concerns on the 2nd Embodiment of this invention was integrated. It is a schematic side view of a fuel cell stack in which a fuel cell impedance measuring apparatus according to a third embodiment of the present invention is incorporated. It is a principal part disassembled perspective view of the fuel cell for a measurement which comprises the said fuel cell stack. It is the VIII-VIII sectional view taken on the line of the said fuel cell in FIG. It is a partial perspective explanatory view of the fuel cell impedance measuring device.

  As shown in FIG. 1, the fuel cell impedance measuring apparatus 10 according to the first embodiment of the present invention is incorporated in a fuel cell stack 12.

  The fuel cell stack 12 includes at least one measurement fuel cell 14S and a plurality of fuel cells 14, and is configured as, for example, an in-vehicle fuel cell stack. In the fuel cell stack 12, a terminal plate 16a, an insulating plate 18a, and an end plate 20a are disposed at one end of the fuel cell 14 in the stacking direction (arrow A direction). In the fuel cell stack 12, a terminal plate 16b, an insulating plate 18b, and an end plate 20b are disposed at the other end in the stacking direction.

  The terminal plate 16a is accommodated in the insulating plate 18a, and the terminal portion 16at projects to one end side in the stacking direction. The terminal plate 16b is accommodated in the insulating plate 18b, and the terminal portion 16bt protrudes to the other end side in the stacking direction. An external load 22 is connected to the terminal portions 16at and 16bt.

  As shown in FIG. 2, the fuel cell 14S includes an electrolyte membrane / electrode structure (electrolyte / electrode structure) 24, and a first separator 26 and a second separator 28 that sandwich the electrolyte membrane / electrode structure 24. Prepare. The first separator 26 and the second separator 28 are constituted by, for example, a metal separator or a carbon separator.

  One end edge of the fuel cell 14S in the direction of arrow B (the horizontal direction intersecting the direction of arrow A in FIG. 1) communicates with each other in the direction of arrow A, which is the stacking direction. An oxidant gas supply communication hole 30a for supplying a cooling medium, a cooling medium supply communication hole 32a for supplying a cooling medium, and a fuel gas discharge communication hole 34b for discharging a fuel gas, for example, a hydrogen-containing gas. Are arranged in the direction of arrow C (vertical direction).

  The other end edge of the fuel cell 14S in the direction of arrow B communicates with each other in the direction of arrow A, a fuel gas supply communication hole 34a for supplying fuel gas, and a cooling medium discharge communication for discharging the cooling medium. The holes 32b and the oxidant gas discharge communication holes 30b for discharging the oxidant gas are arranged in the arrow C direction.

  The electrolyte membrane / electrode structure 24 includes, for example, a solid polymer electrolyte membrane 36 in which a perfluorosulfonic acid thin film is impregnated with water, and a cathode electrode 38 and an anode electrode 40 sandwiching the solid polymer electrolyte membrane 36. Prepare.

  As shown in FIG. 3, the cathode electrode 38 includes an electrode catalyst layer 38a joined to one surface of the solid polymer electrolyte membrane 36, and a gas diffusion layer made of carbon paper or the like disposed on the electrode catalyst layer 38a. 38b. The anode electrode 40 has an electrode catalyst layer 40a joined to the other surface of the solid polymer electrolyte membrane 36, and a gas diffusion layer 40b made of carbon paper or the like disposed on the electrode catalyst layer 40a. The electrode catalyst layers 38 a and 40 a are formed, for example, by uniformly applying porous carbon particles having a platinum alloy supported on the surface thereof to both surfaces of the solid polymer electrolyte membrane 36.

  As shown in FIG. 2, an oxidant gas flow path 42 is provided on the surface 26 a of the first separator 26 facing the electrolyte membrane / electrode structure 24. The oxidant gas flow channel 42 has a plurality of flow channel grooves extending in the arrow B direction, and communicates with the oxidant gas supply communication hole 30a and the oxidant gas discharge communication hole 30b. A cooling medium flow path 44 is provided between the surface 26 b of the first separator 26 and the surface 28 b of the second separator 28. The first separator 26 is provided with a first seal member 46a.

  A fuel gas channel 48 is provided on the surface 28 a of the second separator 28 facing the electrolyte membrane / electrode structure 24. Like the oxidant gas flow path 42, the fuel gas flow path 48 has a plurality of flow path grooves extending in the direction of arrow B, and communicates with the fuel gas supply communication hole 34a and the fuel gas discharge communication hole 34b. . The second separator 28 is provided with a second seal member 46b.

  As shown in FIGS. 3 and 4, the impedance measuring apparatus 10 includes a first electrode portion 50 disposed on the anode electrode (one electrode) 40 side of the electrolyte membrane / electrode structure 24, and the electrolyte membrane / electrode structure. A second electrode portion 52 is provided on the cathode electrode (the other electrode) 38 side of the body 24 so as to face the first electrode portion 50. The first electrode unit 50 is disposed outside the electrode catalyst layer 40a, that is, between the electrode catalyst layer 40a and the gas diffusion layer 40b. The second electrode portion 52 is disposed outside the electrode catalyst layer 38a, that is, between the electrode catalyst layer 38a and the gas diffusion layer 38b.

  The impedance measuring apparatus 10 is further provided with a first electrode portion 50 at one end, a first sheet member 54 having the other end extending outward from the electrolyte membrane / electrode structure 24, and a first sheet member 54 at one end. A second electrode member 52 is provided, and the other end portion includes a second sheet member 56 extending outward of the electrolyte membrane / electrode structure 24. The second electrode portion 52 is provided at a substantially symmetrical position with respect to the first electrode portion 50 with the solid polymer electrolyte membrane 36 and the electrode catalyst layers 38a and 40a interposed therebetween. The first sheet member 54 and the second sheet member 56 have electrical insulation, and are formed of, for example, a liquid crystal polymer (LCP).

  As shown in FIG. 4, an AC application wiring 58 a and a measurement wiring 58 b are connected to the first electrode unit 50. The second electrode portion 52 is connected to the AC application wiring 60a and the measurement wiring 60b. On the one end side of the first sheet member 54 and the one end side of the second sheet member 56, only the first electrode portion 50 and the second electrode portion 52 are exposed to the outside, and the other end portions are thermocompression bonded to each other. Etc. are integrated (welded).

  A connector 62 is connected to the other end portions of the first sheet member 54 and the second sheet member 56. The connector 62 is connected to the controller 66 via the cable 64. The controller 66 includes an AC voltage application unit 68, a voltage measurement unit 70, and a current measurement unit 72. As shown in FIG. 1, the AC applying wires 58 a and 60 a are connected to the AC voltage applying unit 68, while the measuring wires 58 b and 60 b are connected to the voltage measuring unit 70 and the current measuring unit 72.

  The impedance measuring device 10 is preferably provided in the vicinity of the inlet communication hole and the outlet communication hole, for example, in the vicinity of the oxidant gas supply communication hole 30a and in the vicinity of the fuel gas supply communication hole 34a. On the other hand, it can be provided in the vicinity of the oxidant gas discharge communication hole 30b or in the vicinity of the fuel gas discharge communication hole 34b.

  As shown in FIG. 1, the fuel cell 14 includes an electrolyte membrane / electrode structure 24, and a first separator 26 and a second separator 28 that sandwich the electrolyte membrane / electrode structure 24. In the fuel cell 14, the same components as those in the fuel cell 14S are denoted by the same reference numerals, and detailed description thereof is omitted. Essentially, the fuel cell 14 has the same configuration as the fuel cell 14S except that the fuel cell impedance measuring device 10 is not incorporated.

  The operation of the fuel cell stack 12 configured as described above will be described below.

  As shown in FIG. 2, an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas supply communication hole 30a, and a fuel gas such as a hydrogen-containing gas is supplied to the fuel gas supply communication hole 34a. Further, a coolant such as pure water or ethylene glycol is supplied to the coolant supply passage 32a.

  The oxidant gas is introduced into the oxidant gas flow path 42 provided in the first separator 26 and moves along the cathode electrode 38 constituting the electrolyte membrane / electrode structure 24. On the other hand, the fuel gas supplied to the fuel gas supply communication hole 34 a is introduced into the fuel gas channel 48 of the second separator 28 and moves along the anode electrode 40 constituting the electrolyte membrane / electrode structure 24.

  Therefore, in each electrolyte membrane / electrode structure 24, the oxidant gas supplied to the cathode electrode 38 and the fuel gas supplied to the anode electrode 40 are consumed by an electrochemical reaction in the electrode catalyst layers 38a and 40a. Power generation is performed.

  Next, the oxidant gas supplied to and consumed by the cathode electrode 38 is discharged to the oxidant gas discharge communication hole 30b. Similarly, the fuel gas consumed by being supplied to the anode electrode 40 is discharged to the fuel gas discharge communication hole 34b.

  Further, the cooling medium supplied to the cooling medium supply communication hole 32 a is introduced into the cooling medium flow path 44 between the first separator 26 and the second separator 28. The cooling medium cools the electrolyte membrane / electrode structure 24 and then is discharged into the cooling medium discharge communication hole 32b.

  During the above power generation, as shown in FIG. 1, the controller 66 outputs a direct current from the fuel cell stack 12 by the external load 22 and superimposes an alternating current on the direct current.

  For this reason, the voltage measuring unit 70 measures the alternating current response voltage with respect to the alternating current, while the current measuring unit 72 measures the alternating current. Accordingly, the AC impedance between the first electrode unit 50 and the second electrode unit 52 is calculated from the measured AC voltage and AC current. Thereby, it becomes possible to detect the alternating current impedance of the local site in the electrode surface of the fuel cell 14S.

  In this case, in the first embodiment, the first electrode portion 50 and the second electrode portion 52 are disposed to face each other corresponding to the local site in the electrode reaction surface of the electrolyte membrane / electrode structure 24. . The first electrode portion 50 is provided at one end of the first sheet member 54, while the second electrode portion 52 is provided at one end of the second sheet member 56. Furthermore, the other end portion of the first sheet member 54 and the other end portion of the second sheet member 56 are integrated, and the first electrode portion 50 and the second electrode portion 52 are accurately located at a desired installation position. It becomes possible to dispose it oppositely.

  For this reason, the impedance measuring device 10 can easily and accurately measure the impedance of a local site in the electrode reaction surface. In addition, the configuration can be simplified at a time, and it can be manufactured economically. As a result, it is possible to easily and accurately measure the impedance of the electrode reaction surface of the fuel cell 14S with a compact and simple configuration.

  FIG. 5 is a cross-sectional explanatory view of a main part of an electrolyte membrane / electrode structure 82 in which the fuel cell impedance measuring device 80 according to the second embodiment of the present invention is incorporated. In addition, the same referential mark is attached | subjected to the component same as the electrolyte membrane and electrode structure 24 which comprises the impedance measuring device 10 which concerns on 1st Embodiment, and the detailed description is abbreviate | omitted.

  In the impedance measuring device 80, the first electrode unit 50 is disposed outside the gas diffusion layer 40 b that constitutes the anode electrode 40. The second electrode portion 52 is disposed outside the gas diffusion layer 38 b that constitutes the cathode electrode 38. In the second embodiment configured as described above, the same effect as in the first embodiment can be obtained.

  FIG. 6 is a schematic side view of a fuel cell stack 102 in which the fuel cell impedance measuring apparatus 100 according to the third embodiment of the present invention is incorporated. The same components as those of the fuel cell stack 12 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIGS. 7 to 9, the impedance measuring apparatus 100 is incorporated in the electrolyte membrane / electrode structure 104. As shown in FIG. 8, the impedance measuring apparatus 100 includes at least a resistor 106 and a third electrode unit 108 that are provided adjacent to the first electrode unit 50. The first electrode unit 50, the resistor 106, and the third electrode unit 108 are electrically connected to the conductive connecting portions 109a and 109b through brazing, spot welding, or the like. The conductive connecting portions 109a and 109b are arranged apart from each other in the planar direction of the resistor 106 by a predetermined distance. The resistor 106 is preferably elongated in length by a meandering shape, a spiral shape or the like, and may include not only a direct current resistance but also an alternating current resistance.

  The resistor 106 and the third electrode part 108 are provided at one end of the third sheet member 110, and the third sheet member 110 extends outward from the electrolyte membrane / electrode structure 104. As shown in FIG. 9, the other end portions of the first sheet member 54, the second sheet member 56, and the third sheet member 110 are integrated with each other by welding or the like.

  The third electrode portion 108 is connected to the AC application wiring 112a and the measurement wiring 112b. The AC application wiring 112 a is connected to the AC voltage application unit 68. The AC voltage application unit 68 may not be used.

  As shown in FIG. 6, the measurement wiring 112 b and the measurement wiring 58 b of the first electrode unit 50 are connected to the current measurement unit 72. In the first electrode unit 50, the AC application wiring 58a can be connected to the voltage measurement unit 70 as a measurement wiring. In the AC voltage application unit 68, AC application wirings 114a and 114b are connected to the terminal units 16at and 16bt.

  In the third embodiment configured as described above, an AC voltage is applied between the terminal portions 16at and 16bt via the AC voltage application unit 68 when the fuel cell stack 102 generates power. The AC voltage application unit 68 is not limited to both ends as long as AC voltage can be applied across the plurality of fuel cells 14S provided with the impedance measuring device 100.

  For this reason, a voltage drop occurs between the first electrode unit 50 and the third electrode unit 108, and a current (alternating current) flows. Therefore, the alternating current is measured by the current measuring unit 72 based on the voltage drop. On the other hand, the voltage measuring unit 70 measures an AC voltage from the potential difference between the first electrode unit 50 and the second electrode unit 52.

  As a result, the same effects as those of the first and second embodiments described above can be obtained, such as the ability to detect the AC impedance of a local portion within the electrode surface of the fuel cell 14S. Furthermore, since it is only necessary to apply an AC voltage to the entire fuel cell stack 102, the measuring device is simplified compared to applying an AC voltage to each individual impedance measuring device 100. In the third embodiment, the same configuration as that of the second embodiment can be adopted.

DESCRIPTION OF SYMBOLS 10, 80, 100 ... Impedance measuring device 12, 102 ... Fuel cell stack 14, 14S ... Fuel cell 24, 82, 104 ... Electrolyte membrane and electrode structure 26, 28 ... Separator 30a ... Oxidant gas supply communication hole 30b ... Oxidation Agent gas discharge communication hole 32a ... Cooling medium supply communication hole 32b ... Cooling medium discharge communication hole 34a ... Fuel gas supply communication hole 34b ... Fuel gas discharge communication hole 36 ... Solid polymer electrolyte membrane 38 ... Cathode electrodes 38a, 40a ... Electrode catalyst Layer 38b, 40b ... Gas diffusion layer 40 ... Anode electrode 42 ... Oxidant gas passage 44 ... Cooling medium passage 48 ... Fuel gas passage 50, 52, 108 ... Electrode section 54, 56, 110 ... Sheet members 58a, 58b , 60a, 60b, 112a, 112b, 114a, 114b... Wiring 66... Controller 68. Voltage measuring unit 72 ... current measuring unit 106 ... resistor

Claims (4)

An impedance measuring device for a fuel cell incorporated in a fuel cell in which an electrolyte / electrode structure provided with electrodes on both sides of an electrolyte and a separator are laminated,
A first electrode portion disposed on one electrode side of the electrolyte / electrode structure, and a second electrode portion disposed opposite the first electrode portion on the other electrode side of the electrolyte / electrode structure; ,
A first sheet member provided at one end and the other end of the first sheet member extending outward of the electrolyte-electrode structure;
A second sheet member provided at one end with the second electrode portion and the other end extending outward of the electrolyte / electrode structure;
With
An impedance measuring device for a fuel cell, wherein an alternating current is applied to the electrolyte / electrode structure from outside. The impedance measuring device for a fuel cell according to claim 1, wherein at least a resistor and a third electrode portion provided adjacent to the first electrode portion,
A third sheet member provided with the resistor and the third electrode part at one end, and the other end extending outward of the electrolyte / electrode structure;
An impedance measuring device for a fuel cell comprising:   3. The fuel cell impedance measuring apparatus according to claim 2, wherein the other end portions of the first sheet member, the second sheet member, and the third sheet member are integrated with each other. Impedance measuring device.   4. The fuel cell impedance measuring device according to claim 1, wherein the first electrode portion and the second electrode portion are outside of each catalyst layer or outside each diffusion layer constituting the electrode. 5. An impedance measuring device for a fuel cell, wherein the impedance measuring device is in contact with the fuel cell.

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