JP2005203236A - Operation characteristic detecting method and operation characteristic detecting device of fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a detecting method detecting an operation characteristic of a cell in a condition near to the condition of the unit cell in a stack. <P>SOLUTION: The detection method has a step (a) changing over the exhaust/non-exhaust of fuel gas from a downstream end of a fuel gas main passage 3A' according to the pressure of the fuel gas circulating an upstream end of a fuel gas tributary passage 12 in a load state taking out current of the cell 20, a step (b) changing over the exhaust/non-exhaust of oxidant gas from the downstream end of an oxidant gas main passage 5A' according to the pressure of the oxidant gas circulating the upstream end of an oxidant gas tributary passage 11 in a load state, and a step (c) detecting an operation characteristic of the cell 20 based on the change over of the exhaust/non-exhaust of the fuel gas or the oxidant gas in steps (a) and (b). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fuel cell operation characteristic detection method and an operation characteristic detection apparatus.

  A fuel cell is a cell that continuously supplies fuel and discharges combustion products, and directly converts the chemical energy of the fuel into electrical energy. Solid polymer fuel cells that use solid polymer electrolyte membranes as electrolyte membranes are used for automobiles and small-scale cogeneration systems because of their low operating temperature, high power density, and instantaneous operation. Development is rapidly progressing as a home stationary type.

  FIG. 6A is an exploded perspective view schematically showing an example of a unit cell that is a basic unit of a polymer electrolyte fuel cell, and FIG. 6B is a perspective view schematically showing the assembled unit cell. FIG. 6C is a perspective view schematically showing a polymer electrolyte fuel cell configured by stacking unit cells.

  As shown in FIGS. 6A and 6B, the cell 20 includes an electrolyte membrane 6 made of a solid polymer, a pair of catalyst layers 7 and 9 arranged so as to sandwich the membrane, and a catalyst layer 7, 9 includes a pair of gas diffusion layers 8 and 10 disposed on the outer surface of the gas diffusion layer 9 and a pair of separators 1 and 2 disposed on the outer surface of the gas diffusion layers 8 and 10. The catalyst layer 7 and the gas diffusion layer 8 constitute an anode 13, and the catalyst layer 9 and the gas diffusion layer 10 constitute a cathode 14. An anode 13 and a cathode 14 are joined to both surfaces of the electrolyte membrane 6 to constitute an electrode electrolyte composite (hereinafter referred to as MEA) 15. The separators 1 and 2 and the electrolyte membrane 6 are formed with a fuel gas supply manifold hole 3A, a fuel gas discharge manifold hole 3B, an oxidant gas supply manifold hole 5A, and an oxidant gas discharge manifold hole 5B. Actually, gaskets are respectively disposed on the outer peripheral portions of both surfaces of the electrolyte membrane 6 so as to surround the anode 13 and the cathode 14, and the fuel gas supply manifold hole 3A, the fuel gas discharge manifold hole 3B, the oxidation gas are provided in each gasket. An agent gas supply manifold hole 5A and an oxidant gas discharge manifold hole 5B are formed, but are not shown here.

  FIG. 7 is a top view schematically showing the main surface of the separator 1 in contact with the gas diffusion layer 8. FIG. 8 is a top view schematically showing the main surface of the separator 2 in contact with the gas diffusion layer 10. As shown in FIG. 7, a fuel gas branch passage 12 connecting the fuel gas supply manifold hole 3 </ b> A and the fuel gas discharge manifold hole 3 </ b> B is formed on the main surface of the separator 1. As shown in FIG. 8, an oxidant gas branch channel 11 connecting the oxidant gas supply manifold hole 5 </ b> A and the oxidant gas discharge manifold hole 5 </ b> B is formed on the main surface of the separator 2.

  The basic unit of a fuel cell is a single cell, but since the voltage obtained from one single cell is small, it is usually used as a stack 30 in which a number of single cells 20 are stacked as shown in FIG. To do. In the stack 30, the fuel gas supply manifold hole 3A of each unit cell 20 continuously forms the fuel gas supply manifold 3A ', and the fuel gas discharge manifold hole 3B of each unit cell 20 continues to the fuel gas discharge manifold hole 3B. , The oxidant gas supply manifold hole 5A of each unit cell 20 is continuously formed to form the oxidant gas supply manifold 5A ', and the oxidant gas discharge manifold hole 5B of each unit cell 20 is continuously formed of the oxidant. A gas exhaust manifold 5B 'is formed. In the stack 30, the fuel gas is supplied from the upstream end of the fuel gas supply manifold 3 </ b> A ′, the fuel gas flows through the fuel gas supply manifold 3 </ b> A ′, and the fuel gas is distributed to the fuel gas branch channel 12 of each unit cell 20. The fuel gas is supplied to the anode 13 of each unit cell 20. In the stack 30, oxidant gas is supplied from the upstream end of the oxidant gas supply manifold 5 A ′, and the oxidant gas flows through the oxidant gas supply manifold 5 B ′, and the oxidant gas branch channel 11 of each unit cell 20. Then, the oxidant gas is diverted, and the oxidant gas is supplied to the cathode 14 of each unit cell 20.

The reaction in each cell 20 will be described. When fuel gas containing hydrogen is supplied from the fuel supply manifold 3A ′ to the anode 13 via the fuel gas branch passage 12, the reaction shown in the following reaction formula (1) occurs in the catalyst layer 7.

H ₂ → 2H ⁺ + 2e ⁻ (1)

Proton (H +) generated in the reaction formula (1) moves through the electrolyte membrane 6 and electrons (e−) through the external circuit to the cathode 14. Of the fuel gas supplied to the fuel gas branch passage 12, the fuel gas that has not contributed to the reaction of the reaction formula (1) is discharged from the fuel gas discharge manifold 3B ′.

When oxidant gas is supplied from the oxidant supply manifold 5A ′ to the cathode 14 via the oxidant gas branch channel 11, oxygen in the oxidant gas, protons that have moved from the anode 13 in the catalyst layer 9, and The reaction shown in the following reaction formula (2) is caused by the electrons and water is generated.

1 / 2O ₂ + 2H ⁺ + 2e ⁻ → H ₂ O (2)

The water generated in the reaction formula (2) and the oxidant gas that has not contributed to the reaction of the reaction formula (2) are discharged from the oxidant gas discharge manifold 5B ′.

  The fuel gas discharged from the fuel gas discharge manifold 3B 'of each unit cell 20 flows through the fuel gas discharge manifold 3B' of the stack 30, and is discharged to the outside from the downstream end thereof. The oxidant gas and water discharged from the oxidant gas discharge manifold 5B 'of each unit cell 20 flow through the oxidant gas discharge manifold 5B' of the stack 30, and are discharged from the downstream end to the outside.

  When the gas flow resistances of the fuel gas branch channel 12 and the oxidant gas branch channel 11 of each unit cell 20 are the same due to the above configuration of the stack 30, the fuel gas and the oxidant at the same flow rate and the same pressure are supplied to each unit cell 20. Gas is distributed.

  In the polymer electrolyte fuel cell, the electrolyte membrane 6 has a physical property that increases the ionic conductivity as the water content increases, so that it is necessary to keep the electrolyte membrane 6 in a wet state. Therefore, the gas supplied to the stack 30 is generally humidified. However, when the wet state is excessive, generation of generated water in the cathode 14 is also added, so that liquid water flows into the pores of the catalyst layers 7 and 9 and the gas diffusion layers 8 and 10, the fuel gas branch channel 12, and the oxidant gas branch channel 11. It stays and gas distribution resistance becomes high. In the present specification, the gas flow resistance of the fuel gas branch flow path 12 and the oxidant gas branch flow path including the gas flow resistance caused by the retention of liquid water in the pores of the catalyst layers 7 and 9 and the gas diffusion layers 8 and 10 are described. 11 gas flow resistance. A state in which battery performance is extremely deteriorated due to an increase in gas flow resistance is called “flooding”. In order to prevent flooding, it is necessary to operate the electrolyte membrane 6 so that excess water is removed safely and promptly while keeping the electrolyte membrane 6 in an appropriate wet state.

  However, the unit cells 20 have individual differences, and even when used in the same stack 30, the gas flow resistance may increase only in the specific unit cells 20. In the unit cell 20 with increased gas flow resistance, the amount of gas inflow is relatively small. FIG. 9A shows the state of gas flow in the stack 30 in which no significant increase in gas flow resistance has occurred in any unit cell 20, and FIG. 9B shows the gas flow resistance in a specific unit cell 20a. It is a figure which shows typically the mode of distribution | circulation of the gas in the stack 30 when extreme increase arises. In FIG. 9, the length of the arrow relatively represents the inflow amount of gas. As shown in FIG. 9A, when the gas flow resistance is not extremely increased in any unit cell 20, the flow rate of the gas supplied to each unit cell 20 is the same. On the other hand, as shown in FIG. 9B, when the gas flow resistance is extremely increased in a specific unit cell 20a, the amount of gas flowing into the unit cell 20a is smaller than that of other unit cells 20. .

  Since the amount of gas consumed in each unit cell 20 is constant, in the unit cell 20a in which the amount of gas inflow is reduced, the gas utilization rate that is the amount of gas consumed relative to the amount of gas inflow increases compared to the other unit cells 20, A voltage drop occurs. And if a gas utilization rate rises, the increase in gas distribution resistance will accelerate, an extreme voltage drop will arise, and flooding will occur. As a result, the energy efficiency of the entire polymer electrolyte fuel cell is lowered.

As a method of suppressing the voltage variation of each unit cell, a fuel cell that changes the flow rate, pressure and / or humidification amount of gas supplied to and / or discharged from each unit cell for each unit cell. An operation method is disclosed (for example, refer to Patent Document 1).
JP 2000-251913 A

  However, the above-described operation method is very complicated because it is necessary to detect the gas flow rate, pressure and / or humidification amount in the stack during operation.

  Differences in the likelihood of flooding between the cells can occur in the manufacturing process of each cell, the process of assembling the stack, and the like. Among these, it is considered that the major factor causing the difference in the likelihood of flooding is the manufacturing process of each unit cell.

  In a polymer electrolyte fuel cell, in order to prevent a decrease in energy efficiency due to flooding generated in a specific unit cell as described above, a unit cell in which a factor that is likely to cause flooding in the manufacturing process has already been generated. Most preferably, it is not incorporated into the. Therefore, it is possible to detect whether or not the cell has a factor that is likely to cause flooding before being incorporated into the stack, and it is desirable to manufacture the stack without such a cell. After the unit cell is incorporated in the stack, it is not preferable because a complicated operation is required to remove the unit cell in which inconvenience has occurred.

  In the stack, the amount of gas supplied to the cell changes according to the gas flow resistance in the cell. Until now, although the method of detecting the power generation characteristics in the state of the unit cell has been known, the gas supply amount is always constant, and it cannot be said that the unit cell in the stack is simulated.

  An object of this invention is to provide the detection method and detection apparatus which can detect the operating characteristic of a single cell on the conditions close | similar to the state of the single cell in a stack.

  To achieve the above object, the present invention provides an anode bonded to one surface of an electrolyte membrane, a cathode bonded to the other surface of the electrolyte membrane, and a pair of separators disposed on the anode and the outer surface of the cathode. A method for detecting operating characteristics of a fuel cell, comprising: a through-hole constituting a fuel gas main passage; a through-hole constituting an oxidant gas main passage; and an upstream end connected to the fuel gas main passage. The fuel cell includes a fuel gas branch channel that guides the fuel gas to the fuel cell, and an oxidant gas branch channel that has an upstream end connected to the oxidant gas main channel and guides the oxidant gas to the cathode. The fuel gas is circulated from the upstream end of the fuel gas to the fuel gas branch channel, the oxidant gas is circulated from the upstream end of the oxidant gas main channel to the oxidant gas branch channel, and a current is taken out from the fuel cell. A step (a) of switching the discharge / non-discharge of the fuel gas from the downstream end of the fuel gas main flow path according to the pressure of the fuel gas flowing through the upstream end of the fuel gas branch flow path in the state; A step of switching between discharge / non-discharge of the oxidant gas from the downstream end of the oxidant gas main flow path in accordance with the pressure of the oxidant gas flowing through the upstream end of the oxidant gas branch flow path in a loaded state ( b) and a step (c) of detecting operating characteristics of the fuel cell on the basis of switching between discharge / non-discharge of the fuel gas or oxidant gas in the steps (a) and (b).

  In step (a), the supplied fuel gas may be discharged from a flow path other than the fuel gas branch flow path according to the pressure. Similarly, in step (b), the supplied oxidant gas is Depending on the pressure, it may be discharged from a channel other than the oxidant gas branch channel. In addition to the fuel gas branch channel and the oxidant gas branch channel, the condition that there is another channel for discharging the gas is the same as that of the single cells in the stack. In the present invention, other channels are circulated according to the pressure of the fluid flowing through the fuel gas branch channel and the oxidant gas branch channel.

  In step (a), when the pressure of the fuel gas flowing through the upstream end of the fuel gas branch passage exceeds a predetermined value, switching from non-discharge to discharge is performed, and in step (b), upstream of the oxidant gas branch passage. It is desirable to switch from non-discharge to discharge when the pressure of the oxidant gas flowing through the end exceeds a predetermined value. This is because it can be easily confirmed whether or not the pressure of the gas flowing through the upstream end of the fuel gas branch channel or the oxidant gas branch channel exceeds a predetermined value.

  The present invention also includes an anode bonded to one surface of the electrolyte membrane, a cathode bonded to the other surface of the electrolyte membrane, and a pair of separators disposed on the outer surface of the anode and the cathode, A method for detecting operating characteristics of a fuel cell comprising a fuel gas branch channel for introducing fuel gas to an anode and an oxidant gas branch channel for leading an oxidant gas to the cathode, the fuel gas main channel, and an oxidant gas Using the main channel, connecting the upstream end of the fuel gas branch channel to the fuel gas main channel, and connecting the upstream end of the oxidant gas branch channel to the oxidant gas main channel; A fuel gas is circulated from the upstream end of the fuel gas main channel to the fuel gas branch channel, an oxidant gas is circulated from the upstream end of the oxidant gas main channel to the oxidant gas branch channel, and current is supplied from the fuel cell. Removed A step (b) of switching between discharge / non-discharge of the fuel gas from the downstream end of the fuel gas main flow path according to the pressure of the fuel gas flowing through the upstream end of the fuel gas branch flow path in a loaded state; A step of switching between discharge / non-discharge of the oxidant gas from the downstream end of the oxidant gas main flow path in accordance with the pressure of the oxidant gas flowing through the upstream end of the oxidant gas branch flow path in the load state (C) and a step (d) of detecting operating characteristics of the fuel cell based on the switching of discharge / non-discharge of the fuel gas or oxidant gas in the steps (b) and (c).

  According to this detection method, a unit cell that does not have a fuel gas main flow channel and an oxidant gas main flow channel inside, and the fuel gas and oxidant from the external fuel gas main flow channel and external oxidant gas main flow channel when incorporated in a stack. Even a single cell configured to directly acquire gas can detect the operating characteristics in a state simulating the state in the stack before being incorporated into the stack.

  The present invention also includes an anode bonded to one surface of the electrolyte membrane, a cathode bonded to the other surface of the electrolyte membrane, and a pair of separators disposed on the outer surface of the anode and the cathode, A through-hole constituting a gas main flow path, a through-hole constituting an oxidant gas main flow path, a fuel gas branch flow path having an upstream end connected to the fuel gas main flow path and leading the fuel gas to the anode, and an upstream end being the above-mentioned An operating characteristic detecting device for a fuel cell, comprising: an oxidant gas branch channel connected to an oxidant gas main channel and leading an oxidant gas to the cathode, the fuel gas supplying fuel gas to the fuel gas main channel Gas supply means, oxidant gas supply means for supplying oxidant gas to the oxidant gas main flow path, an electronic load for taking out current from the fuel cell, and fuel gas flowing through the upstream end of the fuel gas branch flow path A fuel gas main flow path opening / closing means for switching between discharge / non-discharge of the fuel gas from the downstream end of the fuel gas main flow path according to force, and a pressure of the oxidant gas flowing through the upstream end of the oxidant gas branch flow path And an oxidant gas main flow path opening / closing means for switching the discharge / non-discharge of the oxidant gas from the downstream end of the oxidant gas main flow path. When the detection apparatus having such a configuration is used, the detection method can be easily performed.

  For example, the fuel gas main channel opening / closing means is composed of a cylindrical tube having one end connected to the downstream end of the fuel gas main channel and a certain length from the other end immersed in water or mercury. The oxidant gas main channel opening / closing means has a cylindrical shape in which one end is connected to the downstream end of the oxidant gas main channel and a certain length from the other end is immersed in water or mercury. It can consist of tubes. According to such a configuration, when a pressure corresponding to the length of the immersed portion is applied to the liquid interface of a cylindrical tube immersed in water or mercury, fluid flows through the tube and bubbles are generated in the water or mercury. Will occur. Therefore, it is possible to easily detect whether or not the discharge of fluid from the downstream end of the tube is allowed based on the presence or absence of bubbles.

  According to the present invention, for a unit cell constituting a solid polymer fuel cell, it is possible to detect an operation characteristic close to the operation characteristic when the stack is formed at a stage before the stack is formed. The easy unit cell can be detected more accurately in advance, and the stack can be manufactured without such a unit cell, so that the manufacturing efficiency is good. In addition, an energy efficient stack can be easily manufactured.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Single cell operating characteristic detector)
FIG. 1 is a block diagram showing a schematic configuration of an operating characteristic detection device for a single cell according to the present embodiment. This detection apparatus targets the single cell 20 as a detection target, and includes a fuel gas supply means 41, an oxidant gas supply means 51, a fuel gas main flow path opening / closing means 44, an oxidant gas main flow path opening / closing means 54, and the single battery 20. And an electronic load 70 for taking out current from. In addition, since the thing of the structure similar to the cell 20 of the prior art demonstrated using FIGS. 6-8 is used as the cell 20 of a detection object, the cell 20 of a prior art is used for each component of a cell. The same reference numerals are used and the description thereof is omitted. The upstream end of the fuel gas branch passage 12 in the unit cell 20 is connected to the fuel gas supply manifold 3A ′. In FIG. 1, such a connection point is a branch point 3a. The upstream end of the oxidant gas branch channel 11 is connected to the oxidant gas supply manifold 5A ′. In FIG. 1, such a connection point is a branch point 5a. When detecting the operating characteristics of the unit cell 20, the fuel gas supply means 41 is connected to the upstream end of the fuel gas supply manifold 3A ', and the fuel gas main flow path opening / closing means 44 is connected to the downstream end of the fuel gas supply manifold 3A'. Is done. The oxidant gas supply means 51 is connected to the upstream end of the oxidant gas supply manifold 5A ′, and the oxidant gas main flow path opening / closing means 54 is connected to the downstream end of the oxidant gas supply manifold 5A ′. The electronic load 70 is connected to the anode and cathode of the unit cell 20.

  When the fuel gas main channel opening / closing means 44 is in the open state, the downstream end of the fuel gas supply manifold 3A 'is opened, and the fuel gas is allowed to be discharged from the downstream end of the fuel gas supply manifold 3A'. On the other hand, when the fuel gas main channel opening / closing means 44 is in the closed state, the downstream end of the fuel gas supply manifold 3A 'is closed, and the discharge of the fuel gas from the downstream end of the fuel gas supply manifold 3A' is not allowed. Therefore, when the fuel gas main channel opening / closing means 44 is in the closed state, all of the fuel gas supplied from the fuel gas supply means 41 flows from the branch point 3a to the fuel gas branch channel 12 in the unit cell 20. The fuel gas is supplied from the fuel gas branch channel 12 to the anode, and the fuel gas that does not contribute to the reaction shown in the reaction formula (1) is discharged from the downstream end of the fuel gas discharge manifold.

  When the oxidant gas main flow path opening / closing means 54 is in the open state, the downstream end of the oxidant gas main flow path 52 is opened, and discharge of the oxidant gas from the downstream end of the oxidant gas supply manifold 5A 'is allowed. On the other hand, when the oxidant gas main flow path opening / closing means 54 is closed, the downstream end of the oxidant gas supply manifold 5A ′ is closed, and the oxidant gas is discharged from the downstream end of the oxidant gas supply manifold 5A ′. Not allowed. Therefore, when the oxidant gas main flow path opening / closing means 54 is closed, all of the oxidant gas supplied from the oxidant gas supply means 51 passes from the branch point 52b to the oxidant gas branch flow path 11 in the unit cell 20. Circulate. Oxidant gas is supplied from the oxidant gas branch channel 11 to the cathode, and oxidant gas and generated water that do not contribute to the reaction shown in the above reaction formula (2) are discharged from the downstream end of the oxidant gas discharge manifold.

  The fuel gas main channel opening / closing means 44 switches between opening and closing according to the pressure of the fuel gas flowing through the branch point 3a. In the present embodiment, the fluid in the fuel gas supply manifold 3A ′ is closed when the pressure applied to the fuel gas main flow path opening / closing means 44 is below a certain value, and is opened when the pressure is above a certain value. . The pressure applied to the fuel gas main channel opening / closing means 44 changes in accordance with the pressure of the fuel gas flowing through the branch point 3a, and the pressure of the fuel gas flowing through the branch point 3a depends on the gas flow resistance of the fuel gas branch channel 12 and It changes according to the amount of gas supplied from the fuel gas supply means 41. Therefore, for example, when the supply gas amount is constant, the opening and closing of the fuel gas main channel opening / closing means 44 is switched according to the gas flow resistance of the fuel gas branch channel 12. The pressure applied to the fuel gas main channel opening / closing means 44 can be regarded as substantially the same as the pressure of the fuel gas flowing through the branch point 3a.

  The oxidant gas main channel opening / closing means 54 switches between opening and closing according to the pressure of the oxidant gas flowing through the branch point 5a. In this embodiment, the fluid in the oxidant gas supply manifold 5A ′ is closed when the pressure applied to the oxidant gas main flow path opening / closing means 54 is below a certain value, and is opened when the pressure is above a certain value. And The pressure applied to the oxidant gas main flow path opening / closing means 54 changes according to the pressure of the oxidant gas flowing through the branch point 5 a, and the pressure of the oxidant gas flowing through the branch point 5 a is changed in the oxidant gas branch path 11. It varies according to the gas flow resistance and the amount of gas supplied from the oxidant gas supply means 51. Therefore, for example, when the supply gas amount is constant, the opening / closing of the oxidant gas main channel opening / closing means 54 is switched according to the gas flow resistance of the oxidant gas branch channel 11. The pressure applied to the oxidant gas main flow path opening / closing means 54 can be regarded as substantially the same as the pressure of the oxidant gas flowing through the branch point 5a.

  The fuel gas supply means 41 and the oxidant gas supply means 51 can be controlled to supply a certain amount of gas regardless of the gas flow resistance of the fuel gas branch flow path 12 and the oxidant gas branch flow path 11, It is also possible to control the gas supply amount according to the current value of the electronic load 70 so that the gas utilization rate is obtained.

  In the method for detecting the operating characteristics of a single cell by this detection device, the supply of gas from the supply means 41 and 51 and the acquisition of current by the electronic load 70 are continued for a predetermined time, and the operation of the opening and closing means 44 and 54 is detected. If the fuel gas main flow path opening / closing means 44 or the oxidant gas main flow path opening / closing means 54 is opened within a predetermined time, it is determined that the battery is likely to be flooded. In general, the oxidant gas branch channel 11 is more likely to increase the gas flow resistance than the fuel gas branch channel 12. This is because the oxidant gas branch channel 11 also serves as a discharge channel for the water generated at the cathode, and increases the gas flow resistance when the water stays. The pressure at which switching occurs in the fuel gas main channel opening / closing means 44 and the oxidant gas main channel opening / closing means 54 is performed under the same operating conditions as those at the time of detecting the pressure at the boundary between a normal unit cell and a unit cell in which flooding is likely to occur. Obtain in advance and set to that value.

  Although not shown, it is also possible to provide a power generation characteristic detecting means for detecting power generation characteristics such as the voltage of the unit cell 20, for example. According to the power generation characteristic detecting means, it can be directly confirmed that flooding has occurred, that is, that the battery performance has been extremely lowered.

In the present embodiment, the configuration of the detection device in the case where the unit cell 20 in which the fuel gas supply manifold 3A ′ and the oxidant gas supply manifold 5A ′ are formed is the detection target is shown. A unit cell having a configuration in which the gas is directly led from the manifold and the oxidant gas supply manifold to the internal fuel gas branch channel and the oxidant gas branch channel can be set as a detection target. In this case, the detection device is configured to include a fuel gas supply manifold and an oxidant gas supply manifold.
(Specific configuration example of single cell operating characteristic detection device)
FIG. 2 is a perspective view schematically showing the configuration of the unit cell operating characteristic detection apparatus according to the present embodiment, and particularly shows the specific configuration of the fuel main channel opening / closing means and the air main channel opening / closing means.
As shown in FIG. 2, the fuel gas main channel opening / closing means 44 includes a fuel gas circulation pipe 42 connected to the downstream end of the fuel gas supply manifold 3A ′, and a graduated cylinder 43 in which purified water is injected and arranged horizontally. Become. In the graduated cylinder 43, a part from the downstream end of the fuel gas circulation pipe 42 is immersed in water so that the central axis thereof is in the vertical direction. The vertical length of the immersed portion of the fuel gas distribution pipe 42 is La (mm), the height of the water surface of the graduated cylinder 43 is Ha (mm), and the height of the water surface in the fuel gas distribution pipe 44 is ha (mm). The difference between Ha (mm) and ha (mm) is Pa (mm). In the graduated cylinder 43, when a pressure greater than La (mmaq) is applied to the water surface in the fuel gas flow pipe 42, bubbles are generated. That is, the downstream end of the fuel gas circulation pipe 42 is opened, and the fuel gas is discharged from the downstream end of the fuel gas supply manifold 3A ′.

  As shown in FIG. 2, the oxidant gas main flow path opening / closing means 54 includes an oxidant gas flow pipe 52 connected to the downstream end of the oxidant gas supply manifold 5A ′, and a female that is horizontally injected with purified water. It consists of a cylinder 53. In the graduated cylinder 53, a part from the downstream end of the oxidant gas flow pipe 52 is immersed in water so that the central axis thereof is in the vertical direction. The vertical length of the immersed portion of the oxidant gas flow pipe 52 is Lc (mm), the height of the water surface of the graduated cylinder 53 is Hc (mm), and the height of the water surface in the fuel gas flow pipe 54 is hc (mm). ), And the difference between Hc (mm) and hc (mm) is Pc (mm). In the graduated cylinder 53, when a pressure greater than Lc (mmaq) is applied to the water surface in the oxidant gas flow pipe 52, bubbles are generated. That is, the downstream end of the oxidant gas flow pipe 52 is opened, and the oxidant gas is discharged from the downstream end of the oxidant gas supply manifold 5A '.

  The liquid substance in the graduated cylinders 43 and 53 is not limited to purified water, and may be any substance that can measure the pressure applied to the water surface of the fuel gas circulation pipe 42 and the oxidant gas circulation pipe 52, such as mercury. Can be used.

  In this embodiment, the supply of gas from the supply means and the acquisition of current by the electronic load 70 are continued for a predetermined time, and flooding is likely to occur depending on whether or not bubbles are generated from the graduated cylinders 43 and 53 within the predetermined time. Whether or not the battery is a cell is detected. By following changes in Pa and Pc over time, a change in the gas flow resistance in the battery 20 can be detected. By detecting the degree of occurrence of flooding, the degree of progress of flooding can be detected. In addition, the voltage change of the unit cell may be detected.

A unit cell constituting the polymer electrolyte fuel cell was manufactured, and then the operating characteristics of the unit cell were detected using the detection apparatus shown in FIG.
(Manufacture of single cells)
First, a catalyst paste for the anode 13 was produced. Carbon powder having an average particle size of 30 nm (manufactured by AKZO, Ketjen Black) is immersed in an aqueous solution in which chloroplatinic acid and ruthenium chlorate are dissolved, and then subjected to reduction treatment, whereby platinum-ruthenium is added to the carbon powder. Was supported. At this time, the average particle diameters of the platinum particles and the ruthenium particles were both about 3 nm, and the loading ratio of the platinum particles and the ruthenium particles with respect to the carbon powder was 30 wt% and 24 wt%, respectively. This catalyst-supported carbon powder was dispersed in a 50% by weight alcohol solution of perfluorosulfonic acid (Flemion solution, manufactured by Asahi Glass Co., Ltd.), which is a hydrogen ion conductive polymer electrolyte, and slurried. This was used as a catalyst paste for the anode 13. The weight mixing ratio of perfluorosulfonic acid and carbon powder in the catalyst paste was 1.6: 1.0.

  Next, a catalyst paste for the cathode 14 was produced. Carbon powder with an average particle size of 30 nm (manufactured by AKZO, Ketjen Black) was immersed in an aqueous solution in which chloroplatinic acid was dissolved, and then this was subjected to reduction treatment, whereby platinum was supported on the carbon powder. At this time, the average particle diameter of the platinum particles was about 3 nm, and the loading ratio of the platinum particles to the carbon powder was 50% by weight. This catalyst-supported carbon powder was dispersed in a 50% by weight alcohol solution of perfluorosulfonic acid (Flemion solution, manufactured by Asahi Glass Co., Ltd.), which is a hydrogen ion conductive polymer electrolyte, and slurried. This was used as a catalyst paste for the cathode 14. The weight mixing ratio of perfluorosulfonic acid and carbon powder in the catalyst paste was 1.0: 1.0.

Slurry containing these catalyst-supporting carbons is dried on a polypropylene film substrate to form catalyst layers 7 and 9, which are transferred to both sides of a polymer electrolyte membrane (Nafion 112, manufactured by DuPont) by hot pressing, with a catalyst layer. An electrolyte membrane was obtained. The catalyst layers 7 and 9 were 10 cm square, and the electrode area was 100 cm ² .

  A plain weave carbon cloth (manufactured by Nippon Carbon Co., Ltd., GF-20-31E) made of PAN (polyacrylonitrile) as a base material is coated with a conductive water-repellent layer. It was set to 10. The conductive water repellent layer will be described. After dispersing granules of acetylene black (manufactured by Denki Kagaku Kogyo) in water to which a surfactant (Triton-X) has been added, an aqueous dispersion of polytetrafluoroethylene (PTFE) (manufactured by Daikin, D-1) And kneaded well to make a conductive water-repellent layer slurry. The weight composition ratio of this slurry was water: acetylene rack: PTFE: surfactant = 40: 10: 3: 1. After coating the slurry on the carbon cloth, the conductive water-repellent layer was fixed to the carbon cloth while removing the surfactant by baking at 300 ° C. for 3 hours in an electric furnace to form gas diffusion layers 8 and 10. . The gas diffusion layers 8 and 10 were cut into 10.2 cm square larger than the catalyst layers 7 and 9 by 1 mm in circumference.

Next, a pair of gas diffusion layers 8 and 10 are bonded to both surfaces of the catalyst-attached electrolyte membrane so that the conductive water-repellent layer is in contact with the catalyst reaction layers 7 and 9, and the pint rubber is provided around the gas diffusion layers 8 and 10. A manufactured gasket was placed and hot pressed at 100 ° C., 10 kgf / cm ² for 5 minutes to obtain MEA15.

  The separators 1 and 2 were obtained by applying gas flow paths 11 and 12 to a resin-impregnated graphite plate having a thickness of 3 mm by cutting. Although not shown, the gas flow path 12 of the separator 1 on the anode 13 side is a serpen type flow path composed of three flow paths having a rib width of 1.0 mm and a groove width of 1.0 mm, and the gas flow path of the separator 2 on the cathode side. Was a serpen type flow path comprising 6 flow paths with a rib width of 1.0 mm and a groove width of 1.0 mm.

The MEA 15 was sandwiched in the order of the separators 1 and 2, the current collector plate, the insulating plate, and the end plate, and fastened with a fastening pressure of 10 kgf / cm 2 to obtain a unit cell 20.
(Detection of cell operating characteristics)
In this detection, hydrogen gas was used as the fuel gas, and air was used as the oxidant gas. Before detecting the operating characteristics of the unit cell, using the detection device shown in FIG. 3, the current density obtained by the electronic load 70 is 0.15 A / cm ² and the hydrogen gas utilization rate is 60% to 80%. Then, the pressure applied to the downstream end of the fuel gas supply manifold 3A ′ was measured using a pressure gauge (KL-71 manufactured by Nagano Keiki Co., Ltd.) 45. The hydrogen gas utilization rate was changed every 5%. The pressures of 30 unit cells 20 were measured, and Table 1 shows values that are approximately 10% higher than the average value. In each hydrogen gas utilization rate, when a pressure approximately 10% higher than the average value is applied to the water surface of the fuel gas circulation pipe 42 shown in FIG. 2, it can be considered that flooding has occurred. Similarly, at the downstream end of the air gas supply manifold 5A ′ using the detection device shown in FIG. 3 under the conditions of a current density of 0.15 A / cm ² acquired by the electronic load 70 and an air utilization rate of 60% to 80%. Such pressure was measured using a pressure gauge 55. The air utilization rate was changed every 5%. The pressures of the 30 single cells 20 were measured, and Table 2 shows values that are approximately 10% higher than the average value. In each air utilization rate, when a pressure approximately 10% higher than the average value is applied to the water surface of the air circulation pipe 52 shown in FIG. 2, it can be considered that flooding has occurred.

次に、図２に示す検出装置を用いて、検出対象の単電池の動作特性、具体的にはフラッディングが生じやすいか否かを検出した。詳細な検出条件は、負荷７０により取り出す電流密度を０．１５Ａ／ｃｍ^２、燃料ガス供給マニフォルド３Ａ’の上流端から、露点６５℃、水素ガス利用率が７０％となるように水素ガスを供給した。そして、Ｌａは水素ガス利用率が７０％のときの表１の値である８５０ｍｍとした。酸化剤ガス供給マニフォルド５Ａ’の上流端から、露点７０℃、空気利用率が７０％となるように空気を供給した。そして、Ｌｃは空気利用率が７０％のときの表２の値である３７５（ｍｍ）とした。上記条件にて、水素ガス及び空気ガスの供給と負荷による電流の取得を１５分間継続して行い、いずれのメスシリンダー４３，５３からも気泡が発生しなかった単電池はフラッディングが生じにくい良好品であると判定した。尚、いずれかのメスシリンダー４３，５３から気泡が発生した単電池２０については、気泡が発生した時点で検出を終了し、フラッディングが生じやすい不良品であると判定した。

Next, using the detection apparatus shown in FIG. 2, it was detected whether or not the operating characteristics of the single cell to be detected, specifically, whether flooding is likely to occur. The detailed detection condition is that the current density taken out by the load 70 is 0.15 A / cm ² , and the hydrogen gas is supplied from the upstream end of the fuel gas supply manifold 3 A ′ so that the dew point is 65 ° C. and the hydrogen gas utilization rate is 70%. did. La was 850 mm, which is the value in Table 1 when the hydrogen gas utilization rate was 70%. Air was supplied from the upstream end of the oxidant gas supply manifold 5A ′ so that the dew point was 70 ° C. and the air utilization rate was 70%. Lc was set to 375 (mm) which is the value in Table 2 when the air utilization rate was 70%. Under the above conditions, supply of hydrogen gas and air gas and acquisition of current by load are continued for 15 minutes, and the unit cell in which no bubbles are generated from any of the graduated cylinders 43, 53 is a good product that is less prone to flooding. It was determined that In addition, about the cell 20 which the bubble generate | occur | produced from either graduated cylinder 43,53, the detection was complete | finished when the bubble generate | occur | produced, and it determined with it being a defective product which is easy to produce flooding.

In the above detection, a stack was manufactured using 20 single cells determined to be good, and the power generation characteristics of the stack were detected. The power generation characteristic detected here is a change with time of the voltage of each unit cell in the stack. As detailed detection conditions, the current density taken out by the load was 0.15 A / cm ² , and hydrogen gas having a dew point of 65 ° C. was supplied from the upstream end of the fuel gas supply manifold 3 A ′ so that the hydrogen gas utilization rate would be 70%. . Air having a dew point of 70 ° C. was supplied from the upstream end of the oxidant gas supply manifold 5A ′ so that the air utilization rate would be 70%.

  The results are shown in FIG. As can be seen from FIG. 4, no voltage drop was observed from any single cell even after 20 hours. That is, no decrease in battery performance in the stack was observed.

  As a comparative example, a stack was selected by randomly selecting 20 unit cells for which the operation characteristics of the unit cell were not detected, and the power generation characteristics of the stack were detected under the same conditions as described above. The results are shown in FIG. As can be seen from FIG. 5, flooding occurred in two of the 20 cells.

  In this test, a single cell in which a sudden drop in voltage was observed was taken out and measured using the detection device shown in FIG. 2 while changing the air utilization rate. As a result, bubbles were found in the cylinder 53 at an air utilization rate of 75%. Occurred.

  The present invention is useful when manufacturing a polymer electrolyte fuel cell. Since the stack can be manufactured excluding the single cells that are likely to be flooded in advance, it is possible to manufacture a polymer electrolyte fuel cell with high energy efficiency without performing complicated operations.

The block diagram which shows the structure of the outline of the operating characteristic detection apparatus of the cell of this embodiment. The perspective view which shows the structure of the outline of the operating characteristic detection apparatus of the cell of this embodiment. It is a figure which shows the pressure detection method in a cell. The figure which shows the voltage detection result of the stack | stuck of an Example. The figure which shows the voltage detection result of the stack of a comparative example. The figure which shows typically the structure of a polymer electrolyte fuel cell and the single cell which comprises it. The top view which shows the main surface of the separator in which the fuel gas branch flow path was formed. The top view which shows the main surface of the separator in which the oxidizing gas branch flow path was formed. (A) The figure which shows typically the mode of the distribution | circulation of the gas in the stack in which gas distribution resistance has not increased in any unit cell, and (b) the stack in which gas distribution resistance has increased in one unit cell.

Explanation of symbols

1, 2 separator
3A Fuel gas supply manifold hole 3A 'Fuel gas supply manifold 3B Fuel gas discharge manifold hole 3B' Fuel gas discharge manifold 5A Oxidant gas supply manifold hole 5A 'Oxidant gas supply manifold 5B Oxidant gas discharge manifold hole 5B' Oxidant gas Exhaust manifold 7,9 Catalyst layer 8,10 Gas diffusion layer 11 Oxidant gas branch channel 12 Fuel gas branch channel 13 Anode 14 Cathode 15 MEA
20 unit cell 30 stack 41 fuel gas supply means 42 fuel gas distribution pipe 43 graduated cylinder 44 fuel gas main flow path opening / closing means 51 oxidant gas supply means 52 oxidant gas flow pipe 53 graduated cylinder 54 oxidant gas main flow path opening / closing means 70 electron load

Claims (5)

An operating characteristic detection method for a fuel cell, comprising: an anode bonded to one surface of an electrolyte membrane; a cathode bonded to the other surface of the electrolyte membrane; and a pair of separators disposed on the anode and the outer surface of the cathode. And
A through hole constituting the fuel gas main passage, a through hole constituting the oxidant gas main passage, a fuel gas branch passage having an upstream end connected to the fuel gas main passage and leading the fuel gas to the anode, and an upstream end comprising The fuel cell comprises an oxidant gas branch channel connected to the oxidant gas main channel and leading the oxidant gas to the cathode,
A fuel gas is circulated from the upstream end of the fuel gas main channel to the fuel gas branch channel, an oxidant gas is circulated from the upstream end of the oxidant gas main channel to the oxidant gas branch channel, and a current is supplied from the fuel cell. A step (a) of switching between discharge / non-discharge of the fuel gas from the downstream end of the fuel gas main flow path in accordance with the pressure of the fuel gas flowing through the upstream end of the fuel gas branch flow path in the load state where )When,
A step of switching between discharge / non-discharge of the oxidant gas from the downstream end of the oxidant gas main flow path in accordance with the pressure of the oxidant gas flowing through the upstream end of the oxidant gas branch flow path in the load state (B) and
Detecting an operating characteristic of the fuel cell based on switching between discharge / non-discharge of the fuel gas or the oxidant gas in the steps (a) and (b);
A method for detecting operating characteristics of a fuel cell. In step (a), when the pressure of the fuel gas flowing through the upstream end of the fuel gas branch passage exceeds a predetermined value, switching from non-discharge to discharge,
2. The operation characteristic detection of the fuel cell according to claim 1, wherein in step (b), when the pressure of the oxidant gas flowing through the upstream end of the oxidant gas branch passage exceeds a predetermined value, switching from non-discharge to discharge is performed. Method. An anode joined to one side of the electrolyte membrane, a cathode joined to the other side of the electrolyte membrane, and a pair of separators arranged on the anode and the outer surface of the cathode, and guides fuel gas to the anode An operation characteristic detection method for a fuel cell, in which a fuel gas branch channel and an oxidant gas branch channel for guiding an oxidant gas to the cathode are formed,
Using the fuel gas main channel and the oxidant gas main channel,
Connecting the upstream end of the fuel gas branch channel to the fuel gas main channel and connecting the upstream end of the oxidant gas branch channel to the oxidant gas main channel;
A fuel gas is circulated from the upstream end of the fuel gas main channel to the fuel gas branch channel, an oxidant gas is circulated from the upstream end of the oxidant gas main channel to the oxidant gas branch channel, and a current is supplied from the fuel cell. A step (b) of switching between discharge / non-discharge of the fuel gas from the downstream end of the fuel gas main flow path in accordance with the pressure of the fuel gas flowing through the upstream end of the fuel gas branch flow path in the loaded state where )When,
A step of switching between discharge / non-discharge of the oxidant gas from the downstream end of the oxidant gas main flow path in accordance with the pressure of the oxidant gas flowing through the upstream end of the oxidant gas branch flow path in the load state (C),
Detecting an operating characteristic of the fuel cell based on switching between discharge / non-discharge of the fuel gas or oxidant gas in the steps (b) and (c);
A method for detecting operating characteristics of a fuel cell. An anode bonded to one surface of the electrolyte membrane, a cathode bonded to the other surface of the electrolyte membrane, and a pair of separators disposed on the anode and the outer surface of the cathode constitute a fuel gas main flow path. A through-hole, a through-hole constituting an oxidant gas main flow path, a fuel gas branch flow path whose upstream end is connected to the fuel gas main flow path and guides fuel gas to the anode, and an upstream end connected to the oxidant gas main flow path An operating characteristic detection device for a fuel cell, comprising: an oxidant gas branch channel connected to guide the oxidant gas to the cathode; and
Fuel gas supply means for supplying fuel gas to the fuel gas main flow path; oxidant gas supply means for supplying oxidant gas to the oxidant gas main flow path; an electronic load for taking out current from the fuel cell; and the fuel. A fuel gas main flow path opening / closing means for switching between discharge / non-discharge of the fuel gas from the downstream end of the fuel gas main flow path according to the pressure of the fuel gas flowing through the upstream end of the gas branch flow path, and the oxidant gas branch flow And an oxidant gas main channel opening / closing means for switching between discharge / non-discharge of the oxidant gas from the downstream end of the oxidant gas main channel according to the pressure of the oxidant gas flowing through the upstream end of the passage Battery operating characteristic detection device. The fuel gas main channel opening / closing means is composed of a cylindrical tube having one end connected to the downstream end of the fuel gas main channel and a fixed length from the other end immersed in water or mercury,
The oxidant gas main channel opening / closing means is composed of a cylindrical tube having one end connected to the downstream end of the oxidant gas main channel and a certain length from the other end immersed in water or mercury. The fuel cell operating characteristic detection device according to claim 4.

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