KR20050016297A - Polymer electrolyte fuel cell and driving method of the same - Google Patents

Abstract

It is to provide a polymer electrolyte fuel cell that can suppress the occurrence of flooding at low load. And a cell stacked body 10 in which a cathode-side separator having an oxidant gas flow groove and a cell having an anode-side separator having a fuel gas flow path groove are stacked. A part or all of the oxidant gas flow path groove is provided to the cathode-side separator. The oxidant gas unit flow passages 21a and 21b are formed to enter and exit, and a part or all of the fuel gas flow path grooves form the fuel gas unit flow passages 22a and 22b to enter and exit the anode side separator, and the cell stacks. Two or more oxidant gas unit flow passages 21a and 21b and fuel gas unit flow passages 22a and 22b in the sieve 10 can be connected in parallel or in series, and the oxidant gas unit flow passages 21a and 21b can be connected to each other. The parallel connection of the gas unit flow paths 22a and 22b is a polymer electrolyte fuel cell in which the direction in which the gas flows is in a direction that does not reverse gravity.

Description

Polymer electrolyte fuel cell and polymer electrolyte fuel cell operation method {POLYMER ELECTROLYTE FUEL CELL AND DRIVING METHOD OF THE SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to fuel cells used in portable power sources, power sources for electric vehicles, home cogeneration systems, and the like, particularly polymer electrolyte fuel cells using a polymer electrolyte.

A fuel cell using a polymer electrolyte generates electric power and heat simultaneously by electrochemically reacting a fuel gas containing hydrogen and a fuel gas containing oxygen such as air. This fuel cell is basically composed of a polymer electrolyte membrane for selectively transporting hydrogen ions and a pair of electrodes formed on both sides of the polymer electrolyte membrane, that is, an anode and a cathode. The electrode is composed of a carbon powder carrying a platinum group metal catalyst as a main component, and a gas diffusion layer having air permeability and electron conductivity formed on the catalyst layer formed on the surface of the polymer electrolyte membrane and on the outer surface of the catalyst layer.

A cell consisting of a polymer electrolyte membrane and a pair of electrodes sandwiched therewith is connected to a plurality of cells to obtain a predetermined voltage. For this reason, cells are stacked between cells in a conductive separator to form a stack. When the fuel gas and the oxidizing gas are supplied to both sides of the separator and the fuel gas and the oxidizing gas are supplied to the respective gas diffusion electrodes, the ionic conduction in the polymer electrolyte membrane and the chemical reaction of each gas diffusion electrode proceed. A voltage is generated between the gas diffusion electrodes, and power is supplied to the external circuit through a pair of separators at both ends having a function of the collecting electrodes. In such power generation, supplying the supply gas to the electrode surface of the gas diffusion electrode as evenly as possible increases the gas utilization rate and improves the power generation efficiency and output performance.

In order to prevent the fuel gas and the oxidant gas supplied to the electrode from leaking out or the two kinds of gases to mix with each other, a polymer electrolyte membrane is sandwiched around the electrode and a gas seal material or a gasket is disposed. These gas seal materials and gaskets are previously assembled integrally with an electrode and a polymer electrolyte membrane. This is called MEA (electrolyte membrane electrode assembly). On the outside of the MEA, a conductive separator for mechanically fixing this and electrically connecting adjacent MEAs in series with each other is disposed. In the part which contacts the MEA of a separator, the gas flow path for supplying reaction gas to an electrode surface, and conveying a product water or a surplus gas is formed. Although a gas flow path can be provided separately from a separator, the method of forming a groove in the surface of a separator and making it a gas flow path is common.

In order to supply the reaction gas to the gas flow passage and to discharge the reaction gas and the generated water from the gas flow passage, the pipe for supplying the gas or the pipe from the gas flow passage branches into the number of separators to be used. A piping jig that connects the branching end directly into the groove of the separator is required. This jig is called a manifold, and the type that connects directly from the gas supply pipe is called an external manifold. Unlike this external manifold, there is a type of manifold called an internal manifold with a simpler structure. An internal manifold is a hole which penetrates through the separator which provided the groove | channel for a gas flow path, and makes the entrance and exit of a gas flow path to this hole, and supplies or discharges a reaction gas directly from this hole.

In order to form an internal manifold, a separator is formed by penetrating a hole called a manifold hole so that the entrance and exit of the gas flow passage is connected to the manifold hole, and the reaction gas is distributed from the manifold hole to each gas flow passage. Lose.

Since the fuel cell generates heat during operation, the fuel cell must be cooled with cooling water or the like in order to keep the battery in a good temperature state. Usually, for every 1 to 3 cells, a cooling unit for flowing cooling water is provided.

These MEAs, separators, and cooling sections are alternately overlapped, 10 to 200 cells are stacked, and then sandwiched by end plates through current collector plates and insulating plates, and fixed at both ends by fastening rods.

The configuration of the gas flow path of the separator for supplying gas to the gas diffusion electrode is important not only in terms of gas utilization, but also in terms of efficient current collection of current generated at the gas diffusion electrode and removal of heat generated at the gas diffusion electrode. Conventionally, it is proposed that the gas flow path formed on the separator side be a serpentine type that meanders or a plurality of configurations in which the flow paths are parallel (for example, Japanese Patent Application Laid-Open No. 50-8777 and See Japanese Patent Application Laid-open No. Hei 7-263003).

Perfluorosulfonic acid type materials have been used for the polymer electrolyte of this type of battery. Since the polymer electrolyte membrane exhibits ion conductivity in a state of containing water, it is usually necessary to humidify the fuel gas or the oxidant gas and supply it to the battery. On the cathode side, since water is generated by the reaction, when a humidified gas is supplied to a dew point higher than the operating temperature of the battery, condensation occurs in the gas flow passage inside the battery or inside the electrode, There is a problem that the battery performance is not stabilized or the performance is deteriorated due to clogging or the like. In general, a phenomenon in which a decrease in battery performance or an operation instability caused by excessively wetting occurs is called a flooding phenomenon. In the case of using the polymer electrolyte fuel cell as a power generation system, systemization including humidification of supply gas and the like is necessary. In order to simplify the system and improve the system efficiency, it is desirable to reduce the dew point of the humidified gas supplied even a little.

As described above, in view of prevention of flooding phenomenon, improvement of system efficiency, and simplification of the system, it is common to supply the supply gas by humidifying the gas so as to have a dew point slightly lower with respect to the battery temperature.

However, in order to improve the performance of the battery, it is necessary to improve the ionic conductivity of the polymer electrolyte membrane, and for that purpose, it is preferable to supply humidification of the supply gas at a humidity close to 100% relative humidity or 100% relative humidity. In addition, it is understood that it is preferable to supply the supply gas with high humidity from the viewpoint of durability of the polymer electrolyte membrane. In the case of supplying a gas having a humidity close to 100% relative humidity, the above-mentioned flooding is a problem.

In order to prevent this flooding, the following technique has been proposed (for example, see Japanese Patent Laid-Open No. H10-106594).

That is, the gas flow path of the separator is constituted by an inlet flow path groove and an outlet flow path groove which are connected to the inlet manifold and the outlet manifold, respectively, and an intermediate flow path groove which connects the inlet flow path groove and the outlet flow path groove. . The inlet flow path grooves and the outlet flow path grooves are in a lattice shape, and the intermediate flow path grooves are folded in a plurality of times, and the plurality of parallel independent flow path grooves and the refolded portions of the independent flow path grooves are formed in the grid shape flow path grooves.

In order to prevent the stagnation of the supply gas by flooding with the reaction product water, various gas flow path grooves have been devised from the past, and there are two types in which the gas flow path becomes a lattice shape and one flow path from the inlet to the outlet. . In the lattice type, there is no pooling of water such as flooding, but the overall uniform gas diffusion performance is poor, and the drainage performance such as a part is closed is inferior. In addition, one flow path type has good gas diffusivity, but the flow resistance increases, so that it is necessary to increase the original pressure on the gas supply device side, and the auxiliary mechanical power increases, resulting in a decrease in system efficiency.

In the structure of Japanese Patent Application Laid-open No. Hei 10-106594, the reaction is concentrated in the inlet flow path groove because the inlet flow path groove portion has increased gas diffusivity, promoted the reaction of this portion, and improved the overall electrical conversion energy efficiency. As a result, deterioration of the catalyst layer of the polymer electrolyte membrane or the gas diffusion electrode proceeds, and the problem remains in durability. In addition, in the outlet flow path groove portion, the flow path area is increased to secure drainage to prevent flooding.However, since the flow path area is wide, the flow of gas is uneven and not constant. The state in which a part of is closed occurs, and gas cannot be supplied to this part, and flooding cannot be prevented completely.

As another method for avoiding flooding, it is conceivable to blow up condensed water by increasing the flow velocity in the separator flow path portion of the feed gas.

However, in order to increase the supply gas flow rate, it is necessary to supply gas at a high pressure, and the system efficiency of the gas supply blower or compressor in the case of systemization must be extremely increased, resulting in deterioration of system efficiency. do. In addition, when the flooding phenomenon occurs on the anode side, it causes a deficiency of fuel gas, which becomes fatal in the battery. This is because when a load current is forcibly taken in a state where fuel gas is insufficient, carbon carrying an anode catalyst reacts with water in the atmosphere because electrons and protons are produced without fuel. As a result, the catalyst layer of the anode is destroyed by elution of carbon in the catalyst layer.

In addition, in a system equipped with a laminated battery, in consideration of the merchandise, it is indispensable not only to operate the battery under rated output conditions but also to perform a low load operation in which the output is suppressed in accordance with electric power demand. In low load operation, in order to maintain efficiency, it is necessary to make the utilization rate of fuel gas and oxidant gas into the same conditions as a rated operation. In other words, when the load is reduced to 1/2, for example, at the time of rated operation, when the flow rate of fuel gas or oxidant gas is not reduced to about 1/2, extra fuel gas or oxidant gas is used. The efficiency is lowered. However, when the gas utilization in the gas flow path is kept constant under low load operation, the gas flow rate in the gas flow path decreases, and condensed water and generated water cannot be discharged to the outside of the separator, and the flooding phenomenon as described above occurs, resulting in battery performance. There has been a problem of deterioration or instability.

1 is a front view of a cathode side of a conductive separator used in the polymer electrolyte fuel cell according to Embodiment 1 of the present invention.

Fig. 2 is a front view of the anode side of the conductive separator used in the polymer electrolyte fuel cell of Embodiment 1 of the present invention.

Fig. 3 is a view showing conversion of the gas flow to the cathode side of the conductive separator used in the polymer electrolyte fuel cell according to Embodiment 1 of the present invention.

Fig. 4 is a perspective view showing the pipe on the cathode side of the stacked polymer electrolyte fuel cell according to Embodiment 1 of the present invention.

Fig. 5 is a perspective view showing the pipe on the cathode side of the stacked polymer electrolyte fuel cell according to Embodiment 2 of the present invention.

6 is a diagram showing the current-voltage characteristics of the polymer electrolyte fuel cell of Example 1 of the present invention.

7 is a diagram showing the current-voltage characteristics of the polymer electrolyte fuel cell of Example 2 of the present invention.

8 is a view showing a change with time of the voltage of the polymer electrolyte fuel cell of Example 3 of the present invention.

Fig. 9 is a front view of the cathode side separator of cell A in the polymer electrolyte fuel cell of Embodiment 3 of the present invention.

Fig. 10 is a front view of the anode side separator of cell A in the polymer electrolyte fuel cell of Embodiment 3 of the present invention.

Fig. 11 is a front view of the cathode side separator of cell B in the polymer electrolyte fuel cell of Embodiment 3 of the present invention.

12 is a front view of the anode side separator of cell B in the polymer electrolyte fuel cell according to Embodiment 3 of the present invention.

FIG. 13 is a front view of a cathode-side separator showing the flow of oxidant gas in cell A when reaction gas is supplied in series to cells A and B in the polymer electrolyte fuel cell according to Embodiment 3 of the present invention.

Fig. 14 is a front view of an anode separator showing the flow of fuel gas in cell A when the reaction gas is supplied in series to cells A and B in the polymer electrolyte fuel cell according to Embodiment 3 of the present invention.

FIG. 15 is a front view of the cathode-side separator showing the flow of the oxidant gas of the cell B when the reaction gas is supplied in series to the cells A and B in the polymer electrolyte fuel cell according to the third embodiment of the present invention.

FIG. 16 is a front view of an anode-side separator showing the flow of the fuel gas of the cell B when the reaction gas is supplied in series to the cells A and B in the polymer electrolyte fuel cell according to the third embodiment of the present invention.

Fig. 17 is a perspective view showing the entire structure of the polymer electrolyte fuel cell according to Embodiment 3 of the present invention.

Fig. 18 is a perspective view showing the entire structure of the polymer electrolyte fuel cell according to the fourth embodiment of the present invention.

Fig. 19 is a diagram showing the change of voltage in the continuous power generation test of the polymer electrolyte fuel cell of Example 4 of the present invention.

<Explanation of symbols for the main parts of the drawings>

1: MEA 5, 131: current collector

6, 132: insulation plate 7, 133: end plate

10: conductive separator

11a, 11b: Inlet manifold hole of oxidant gas

12a, 12b: Inlet manifold hole of fuel gas

13a, 13b: manifold hole on the outlet side of oxidant gas

14a, 14b: Manifold hole on the exit side of fuel gas

21a: first flow path of oxidant gas

21b: second flow path of oxidant gas

22a: first flow path of fuel gas

22b: second flow path of fuel gas

30: fuel cell

31 pipe leading to the source of oxidant gas

31a, 31b: branch pipe

33a, 33b: branch pipe on the exit side

33: outlet pipe

35, 37, 39: valve

40: mist trap

101, 3L, 3R, 105: manifold of oxidant gas

102, 4L, 4R, 106: fuel gas manifold

10A, 10B: cathode side separator

20A, 20B: anode side separator

11A, 11B, 21A, 21B: Inlet manifold hole of oxidant gas

13A, 13B, 23A, 23B: Inlet manifold hole of oxidant gas

12A, 12B, 22A, 22B: Inlet manifold hole for fuel gas

14A, 14B, 24A, 24B: Inlet manifold hole for fuel gas

15A, 15B, 25A, 25B: Outlet manifold hole of oxidant gas

16A, 16B, 26A, 26B: outlet manifold hole of oxidant gas

130: cell stack

SUMMARY OF THE INVENTION An object of the present invention is to provide a polymer electrolyte fuel cell capable of suppressing flooding at low load and a method of operation thereof in view of the above problems.

In order to solve the above problems, a first aspect of the present invention provides a polymer electrolyte membrane, an anode and a cathode sandwiching the polymer electrolyte membrane, a cathode side separator having an oxidant gas flow path for supplying an oxidant gas to the cathode, and a fuel gas to the anode. And a cell stacked structure in which cells having an anode-side separator having a fuel gas flow path groove for supplying a stacked structure are stacked.

A part or all of the oxidant gas flow path grooves form an oxidant gas unit flow path which is a flow path from the input to the cathode side separator to the output.

A part or all of the fuel gas flow path grooves form a fuel gas unit flow path, which is a flow path from the anode side separator to the output,

Two or more of the oxidant gas unit flow paths in the cell stack can be connected in parallel or in series,

A polymer electrolyte fuel cell in which two or more of the fuel gas unit flow paths in the cell stack can be connected in parallel or in series.

According to the second invention of the present application, with respect to the change in the power generation output, the speed of the oxidant gas passing through the oxidant gas flow path groove maintains the speed at which water does not stay in the oxidant gas flow path groove, The polymer electrolyte fuel cell of the first invention of the present invention, wherein the parallel connection or the series connection is changed so that the speed of the fuel gas passing through maintains the speed at which water does not stay in the fuel gas flow path groove.

In the third invention of the present application, the oxidant gas unit flow path is formed as a part of the oxidant gas flow path groove, and the fuel gas unit flow path is formed as a part of the fuel gas flow path groove,

When connected in parallel, the plurality of oxidant gas unit flow paths formed in the cathode side separators are connected in parallel so that the oxidant gas is supplied simultaneously, and the plurality of fuels formed in the anode side separators. Gas unit flow passages are connected in parallel to each other so that the fuel gas is supplied at the same time,

In the case of being connected in series, all or part of the plurality of oxidant gas unit flow paths formed in each of the cathode side separators are connected to each other in series so that the oxidant gas is supplied in turn, and is formed in each of the anode side separators. All or part of the plurality of fuel gas unit flow passages are the polymer electrolyte fuel cells of the second invention of the present application, which are connected in series to each other so that the fuel gas is sequentially supplied.

In the fourth invention of the present application, the oxidant gas unit flow path is formed in all of the oxidant gas flow path grooves, and the fuel gas unit flow path is formed in all of the fuel gas flow path grooves.

When connected in parallel, the oxidant gas unit flow paths formed in the cathode separators are connected in parallel so that the oxidant gas is supplied simultaneously, and the fuel gas unit flow paths formed in the anode side separators are connected to each other. , Are connected in parallel to each other so that the fuel gas is supplied at the same time,

In the case of being connected in series, all or part of the oxidant gas unit flow path formed in each cathode side separator is connected in series so that the oxidant gas is sequentially supplied, and the fuel formed in each of the anode side separators. All or part of the gas unit flow passages are the polymer electrolyte fuel cells of the second invention of the present application connected in series with each other so that the fuel gas is sequentially supplied.

According to a fifth aspect of the present invention, an inlet oxidant gas manifold connected to an inlet of each oxidant gas unit flow path, an outlet oxidant gas manifold connected to an outlet of each oxidant gas unit flow path, and each fuel gas unit An inlet fuel gas manifold connected to the inlet of the flow path and an outlet fuel gas manifold connected to the outlets of the respective fuel gas unit flow paths,

When the oxidant gas unit flow paths are connected in series, other than the inlet oxidant gas manifold connected to the inlet of the oxidant gas flow path groove and the outlet oxidant gas manifold connected to the outlet of the oxidant gas flow path groove, The inlet oxidant gas manifold and the outlet oxidant gas manifold,

When the fuel gas unit flow paths are connected in series, other than the inlet fuel gas manifold connected to the inlet of the fuel gas flow path groove and the outlet fuel gas manifold connected to the outlet of the fuel gas flow path groove, A polymer electrolyte fuel cell of the third or fourth aspect of the present invention, wherein an inlet fuel gas manifold and an outlet fuel gas manifold are connected.

According to a sixth aspect of the present invention, the oxidant gas unit flow paths and the fuel gas unit flow paths connected in series or in parallel are formed by opening and closing a valve provided outside the stack cell in accordance with the power generation power. 5 is a polymer electrolyte fuel cell of the invention.

The seventh invention of the present application includes an inlet oxidant gas manifold other than an inlet oxidant gas manifold connected to an inlet of the oxidant gas flow path groove and an outlet oxidant gas manifold connected to an outlet of the oxidant gas flow path groove. Inlet side other than the portion to which the outlet oxidant gas manifold is connected, and the inlet fuel gas manifold connected to the inlet of the fuel gas flow path groove and the outlet fuel gas manifold connected to the outlet of the fuel gas flow path groove. A polymer electrolyte fuel cell of the fifth invention of the present invention is provided with a mist trap at a portion where a fuel gas manifold and an outlet fuel gas manifold are connected.

In the eighth invention of the present application, the parallel connection between the oxidant gas unit flow paths is made such that the direction in which the oxidant gas flows does not reverse to gravity,

The parallel connection between the fuel gas unit flow paths is the polymer electrolyte membrane fuel cell according to the first invention of the present application, wherein the direction in which the fuel gas flows is in a direction that does not reverse to gravity.

The ninth aspect of the present invention has a polymer electrolyte membrane, an anode and a cathode sandwiching the polymer electrolyte membrane, a cathode side separator having an oxidant gas passage for supplying an oxidant gas to the cathode, and a fuel gas passage for supplying fuel gas to the anode. A cell stacked body in which cells having an anode side separator are stacked,

A part or all of the oxidant gas flow path grooves form an oxidant gas unit flow path which is a flow path from the input to the cathode side separator to the output.

A part or all of the fuel gas flow path grooves is a method of operating a polymer electrolyte fuel cell in which a fuel gas unit flow path, which is a flow path from the input to the anode side to the output, is formed.

A process in which two or more of said oxidant gas unit flow paths in said cell stacked body are connected in parallel or in series;

A method of operating a polymer electrolyte fuel cell comprising the step of connecting two or more of the fuel gas unit flow paths in the cell stacked body in parallel or in series.

According to the present invention, it is possible to provide a polymer electrolyte fuel cell capable of suppressing the occurrence of flooding at low load and a method of operating the same.

<Embodiment 1>

1 is a front view of the cathode side of the conductive separator, and FIG. 2 is a front view of the anode side as its rear view. The conductive separator 10 includes first and second inlet manifold holes 11a and 11b of oxidant gas, first and second outlet manifold holes 13a and 13b, and first and first fuel gas. Two inlet manifold holes 12a and 12b, and first and second outlet manifold holes 14a and 14b. The separator 10 has, on the cathode side, a first gas passage corresponding to the oxidant gas unit flow passage of the present invention, which extends from the first inlet manifold hole 11a to the first outlet manifold hole 13a. 21a and a second gas flow passage 21b corresponding to the oxidant gas unit flow passage of the present invention, which extends from the second inlet manifold hole 11b to the second outlet manifold hole 13b, the anode On the side, the first gas passage 22a and the second inlet corresponding to the fuel gas unit flow passage of the present invention, which extend from the first inlet manifold hole 12a to the first outlet manifold hole 14a, are provided. It has the 2nd gas flow path 22b corresponding to the fuel gas unit flow path of this invention from the side manifold hole 12b to the 2nd outlet side manifold hole 14b. The oxidant gas flow path groove of the present invention is constituted by the first gas flow path 21a and the second gas flow path 21b. The fuel gas flow path groove of the present invention is constituted by the first gas flow passage 22a and the second gas flow passage 22b.

The gas supply method in the polymer electrolyte fuel cell using this separator will be described below.

First, an oxidant gas supply method at the rated operation will be described with reference to FIG. The path from arrow A to A ', that is, the path from the first inlet manifold hole 11a to the first outlet manifold hole 13a past the first gas passage 21a and from arrow B to B The two paths of the path leading to ', i.e., the path leading from the second inlet manifold hole 11b to the second outlet manifold hole 13b through the second gas passage 21b are connected in parallel. An oxidant gas flows through these two paths simultaneously.

Next, when operating at a load of 1/2 of the rating, as shown in FIG. 3, the two paths, the first gas passage 21a and the second gas passage 21b, are connected in series. That is, the first outlet manifold hole 13a and the second inlet manifold hole 11b are connected outside the cell as indicated by arrow AB. That is, the first gas passage 21a and the second gas passage 21b are connected in series. Thereby, the gas which flows into the 1st inlet manifold hole 11a from arrow A flows in order through the 1st gas flow path 21a and the 2nd gas flow path 21b, and the 2nd outlet side manifold hole 13b. Is discharged to outside. The fuel gas supply method is also the same as above.

FIG. 4 shows piping of an oxidant gas of a stacked polymer electrolyte fuel cell equipped with a separator as described above. The polymer electrolyte fuel cell 30 includes a cell stack in which the MEA 1 and the separator 10 are alternately stacked, a pair of current collector plates 5, an insulating plate 6, and an end plate 7 sandwiching the MEA 1 and the separator 10. And fastening means for fastening them integrally. The pipe 31 which is connected to the supply source of the oxidant gas branches into the first pipe 31a and the second pipe 31b having the valve 35. The first pipe 31a is connected to the manifold provided in the polymer electrolyte fuel cell via the first inlet manifold hole 11a of the separator 10, and the second pipe 31b is the separator 10. It is connected to the manifold installed in the polymer electrolyte fuel cell via the second inlet manifold hole 11b of the (). Similarly, pipes 33a and 33b connected to the manifold communicating with the first outlet manifold hole 13a and the second outlet manifold hole 13b of the separator 10, respectively, are provided. A valve 39 is connected to the pipe 33a, and this and the pipe 33b are connected to the outlet pipe 33. One end of the pipe 31b is connected to the pipe 33a via the bypass valve 37. Each valve is connected to the controller 200.

Although only the cathode side piping is shown in FIG. 4 for the sake of simplicity, the anode side piping can also be configured similarly by arranging them in a symmetrical position. The pipes 31a and 31b branched from the pipe 31 and the pipes 33a and 33b connected to the pipe 33 have the same pipe diameter and can evenly distribute gas to the divided pipes. I have a structure. Here, in order to distribute the gas evenly, it is important to equalize the lengths of the pipes divided into two so that the pressure loss of each pipe is the same, and at the same time, the path lengths of the two gas flow passages shown in FIG. It is important to equalize the pressure loss of the two gas flow paths in order to evenly distribute the gases.

When the polymer electrolyte fuel cell is operated at a rated load, the controller 200 opens the valves 35 and 39 and closes the bypass valve 37. The oxidant gas supplied from the pipe 31 is supplied from the pipes 31a and 31b to the first gas passage 21a and the second gas passage 21b from the manifold holes 11a and 11b, respectively, and the pipe 33a And to the pipe 33 via 33b). In addition, when operating at a load of 1/2 of the rating, the controller 200 closes the valves 35 and 39 and opens the bypass valve 37. The oxidant gas that flowed from the pipe 31a to the first gas flow passage 21a flows from the pipe 33a to the second gas flow passage 21b via the bypass valve 37 and the pipe 31b to pass the pipe 33b. From the pipe 33. That is, in accordance with the change in the power generation output, the parallel connection and the series connection of each gas channel are changed to maintain the gas velocity at which water does not stay in each gas channel.

Here, about the flow path of cooling water is abbreviate | omitted, Therefore, the manifold hole of cooling water is abbreviate | omitted in FIG. However, similarly to the gas flow path, the cooling water flow path may be divided into a plurality of flow paths, and the switching may be performed according to the load in the same manner as the switching of the gas flow path. Although the separator shown above also serves as a cathode side separator and an anode side separator plate, the cooling part by cooling water can be comprised as follows. A cathode-side separator in which an oxidant gas flow path as shown in FIG. 1 is formed on one side, and a coolant flow path is formed on the other side, and a flow path of fuel gas as shown in FIG. 2 on one side, and a coolant on the other side An anode-side separator having a flow path formed therein is combined with a combination separator in which cooling flow paths face each other, as appropriately inserted between MEAs. From the configuration of the gas flow passage shown here, it will be easy for a person skilled in the art to construct a flow path of a plurality of divided cooling water. In the case where the cooling unit is not provided for each cell, it is not necessary to divide the cooling unit into a plurality of units like the gas passage.

The point of this embodiment has a plurality of independent gas flow paths having independent manifold holes in the surface of the separator, and the polymer electrolyte fuel cell system is deteriorated in battery performance during low load operation by simple valve switching or This is to avoid instability.

In the structure of the separator of the conventional polymer electrolyte fuel cell, each gas of the fuel gas and the oxidant gas is supplied from one inlet manifold to the gas passage of the separator and discharged through one outlet manifold. It was. In order to increase the commercialization of the polymer electrolyte fuel cell power generation system, it is necessary to change the load of the polymer electrolyte fuel cell according to electric power demand without lowering the power generation efficiency. To this end, when the load is increased with respect to the rated output, the flow rate of fuel gas and oxidant gas is increased at a corresponding flow rate, and when the load is decreased with respect to the rated output, the fuel gas and the oxidant are flown at a corresponding flow rate. It should be operated with reduced gas flow rate.

Usually, the gas flow path provided in the conductive separator of the polymer electrolyte fuel cell is designed to have the most suitable flow rate at the rated output.

Therefore, when the electric power load is increased, the gas flow rate in the gas flow path increases with the increase of the gas flow rate, and when the electric power load is decreased, the gas flow rate in the gas flow path decreases as the gas flow rate decreases. When the gas flow rate in the gas flow path increases, the pressure loss of the supply gas increases, so that the power generation efficiency decreases slightly due to the increase in auxiliary machinery power, but the gas flow path of the separator increases because the gas flow rate in the gas flow path increases. The dew condensation water and the generated water inside can be removed efficiently, and the flooding phenomenon does not occur. However, in the case of reducing the power load, the gas flow rate in the gas flow path decreases with the decrease in the gas flow rate. When the gas flow rate in the gas flow path is decreased, it is difficult to efficiently remove condensation water and generated water in the gas flow path of the separator due to the degree of decrease in the flow rate, and a flooding phenomenon occurs. At this time, even if the power load is reduced, if the supply gas flow rate is not reduced, the ratio of the auxiliary machine power to the power generation output becomes relatively large, and the power generation efficiency of the power generation system as a whole decreases.

In the present invention, by forming a plurality of independent gas flow passages having independent inlet and outlet manifold holes in the surface of the separator and connecting them in series or in parallel, a polymer which does not cause flooding even during low load operation, in particular, It is to realize an electrolyte fuel cell. For example, when the ratio of the highest load generation output to the lowest load generation output is four to one, four in-plane gas passages of the separator are formed independently, and at the highest load generation, gas is applied in parallel to all gas passages. At the minimum load operation, all four gas passages are connected in series to supply gas. In the middle of the load operation, two adjacent gas flow paths of the four flow paths are connected in series to supply gas. As a result, the same gas flow rate can be maintained in all gas flow paths even during load fluctuations.

As described above, when there are a plurality of gas unit flow paths, when the oxidant gas unit flow paths are connected in series, the oxidant gas manifold and the outlet of the oxidant gas flow path grooves connected to the inlet of the oxidant gas flow path grooves. The inlet oxidant gas manifold and the outlet oxidant gas manifold in each oxidant gas unit flow path other than the outlet oxidant gas manifold connected may be connected. When the fuel gas unit flow paths are connected in series, each of the fuel gas manifolds other than the inlet fuel gas manifold connected to the inlet of the fuel gas channel groove and the outlet fuel gas manifold connected to the outlet of the fuel gas channel groove is The inlet fuel gas manifold and the outlet fuel gas manifold in the fuel gas unit flow passage may be connected.

In addition, when connecting each gas channel in series, connection of each gas channel connects an independent manifold hole using piping outside of a separator, and the condensed water condensed in the intermediate manifold hole is separated by a separator. Since it becomes possible to discharge | emit to the outside of the and condensed water is not supplied to the downstream flow path, stable operation is possible.

As described above, according to the polymer electrolyte fuel cell of the present embodiment, even when partial load operation is performed, the flow rate of the gas in the gas flow passage does not decrease, so that the occurrence of flooding can be suppressed.

However, in general, the fuel cell is advantageous in that it can operate at the rated load. Therefore, in consideration of the actual use situation, it is assumed that the time to operate close to the rated load or the rated load is much longer than the time to operate at the partial load. Therefore, similarly to the polymer electrolyte fuel cell of the present embodiment, even in the rated operation or the partial load operation, the unit flow passages are configured to flow in a direction in which the gas inside does not counter gravity. It can be further suppressed. However, even if some or all of the gas unit flow passages are configured to flow in the direction in which the gas inside the gas flows against gravity, the same effects as described above can be obtained in that flooding under partial load can be suppressed. have.

<Embodiment 2>

In this embodiment, as shown in FIG. 5, the mist trap 40 was inserted in the pipe which connects the 1st exit manifold and the 2nd inlet manifold in Embodiment 1. In FIG. When the reaction gas is supplied so that the relative humidity becomes almost 100%, the reaction gas is in a state containing a large amount of mist due to the generated water, the dew condensation water, or the like when passing through the first gas passage. When this mist is supplied to the gas flow path of a later stage, it will cause the closing of the gas flow path by mist, and there exists a high risk of flooding. For this reason, by inserting the mist trap 40 so that the mist discharged once out of the separator from the outlet of the upstream 1st gas flow path is not supplied to the downstream gas flow path again, the flooding is more reliable with less flooding. Enable driving. The water trapped by the mist trap 40 can be recovered by the fuel cell system and reused. As the mist trap 40, a commercially available mechanical mist trap, for example, used in Example 2, or a wick shape having a water-absorbing effect, for example, such as a yarn, can be used.

Thus, by inserting the mist trap 40 into the connection part of a manifold hole, it becomes possible to ensure discharge | emission of condensate. When the gas flowing through each gas flow path flows in a direction that does not counter gravity, the discharge of condensed water is further promoted. When the gas flow paths are switched in series and in parallel, if the gas flow direction is configured so as not to change, it is possible to allow the gas to flow without always returning to the gravity direction, and more stable operation is possible. In addition, although description of the controller 200 is abbreviate | omitted in FIG. 5, each valve is operated through the controller 200 like the case of FIG.

(Example 1)

Hereinafter, embodiments of the present invention will be described.

25% by weight of platinum particles having an average particle diameter of about 30 kPa are supported on the acetylene black carbon powder, and 25% by weight of platinum-ruthenium alloy particles having an average particle diameter of about 30 kPa are supported on the anode. Each catalyst was produced. These catalyst powders were dispersed in isopropanol, and then mixed with an ethyl alcohol dispersion (premione (manufactured by Asahi Glass Co., Ltd.)) of perfluorocarbon sulfonic acid powder to prepare a paste ink. Using these inks as a raw material, a screen layer was applied to one surface of a carbon nonwoven fabric having a thickness of 250 µm (Toray Co., Ltd. Code No. TGP-H-090) to form a catalyst layer, respectively. The amount of platinum contained in these catalyst layers was 0.3 mg / cm ² , and the amount of perfluorocarbonsulfonic acid was 1.2 mg / cm ² .

Cathodes and anodes formed by forming a catalyst layer on a carbon nonwoven fabric as described above are formed on both sides of the center portion of a hydrogen ion conductive polymer electrolyte membrane (Nafion 112 (trademark) manufactured by DuPont, USA) having an area around the electrode. Each catalyst layer was bonded by hot press so as to contact the electrolyte membrane. A gasket made of a fluorine-based rubber sheet having a thickness of 250 µm was bonded to the electrolyte membrane portion exposed to the outer peripheral portion of the electrode by hot pressing. Thus, an electrolyte membrane electrode assembly (MEA) was produced. As the polymer electrolyte membrane, a thin film of perfluorocarbon sulfonic acid having a thickness of 30 μm was used.

The conductive separator is formed by forming a gas flow path and a manifold hole in an isotropic graphite material having a thickness of 3 mm, and has a structure as shown in FIGS. 1 and 2. The groove width of each gas flow path was 2 mm, the depth was 1 mm, and the rib width between grooves was 1 mm, and the gas flow path groove structure of one pass was set, respectively. In addition, although not shown in FIG. 1 and FIG. 2, the flow path of the cooling water was also divided corresponding to the gas flow path.

Next, the conductive separator and the MEA were alternately stacked to fabricate a polymer electrolyte fuel cell as shown in FIG. 4 in which 50 cells were stacked. The current collector plate was a copper plate gold-plated on the surface, a polyphenylene sulfide plate was used for the insulating plate, and stainless steel was used for the end plate. The clamping pressure of the laminated battery was 10 kgf / cm ² per electrode area, and the laminated battery was configured so that the upper part of the separator shown in FIG. 1 was upward.

The rated operating conditions of this battery are 75% fuel utilization, 40% oxygen utilization, and 0.3 A / cm ² current density.

The solid polymer fuel cell of the present embodiment thus prepared was maintained at 70 ° C, humidified and warmed fuel gas to a dew point of 70 ° C on the anode, and humidified and warmed air to a dew point of 70 ° C on the cathode, respectively. Supplied. The fuel gas consists of 80% of hydrogen gas, 20% of carbon dioxide, and 10 ppm of carbon monoxide.

The current-voltage characteristics were evaluated by varying the current density from 0.075 A / cm ^{2 at} a low load of 25% of the rated voltage to 0.3 A / cm ² at a rated load. However, the utilization rate during the test was made equal to the rated condition. The result is shown in FIG. In FIG. 5, the characteristics of the conventional polymer electrolyte fuel cell, that is, the battery of Comparative Example 1 using a separator having a one-pass gas flow groove configuration, are also described for comparison. In the present embodiment, by switching the more than 0.15A / cm ² in series flow path, 0.15A / cm ² or more parallel flow path was subjected to the test.

6, in the polymer electrolyte fuel cell of this example, flooding occurred due to a decrease in gas flow rate in the battery of Comparative Example 1, and flooding did not occur even near 0.075 A / cm ^2, which was difficult to operate, and thus stable operation. You can see that you can. Although the case where two independent flow paths were used in the present Example was shown, if the pressure loss of each flow path is the same, it can also be set as the structure which has three or more independent flow paths.

(Example 2)

In the present Example, as shown in Embodiment 2, the battery similar to Example 1 was produced except having inserted the mist trap 40. As the mist trap 40, a commercial mechanical mist trap (1-LDC manufactured by Armstrong) was used. This battery was measured for current-voltage characteristics under the same conditions as in Example 1. Here, the pressure loss of the whole flow path in Example 2 was designed as about 60% of the pressure loss of the whole flow path in Example 1. As shown in FIG. This result is shown in FIG. From Fig. 7, according to Example 2, it was confirmed that stable battery output can be obtained with low pressure loss.

(Example 3)

It is preferable to install a battery so that a separator is comprised like FIG. 1 and arrange | positioned as FIG. Normally, the temperature distribution in the cell surface is determined by the direction in which the cooling water flows, and in order to lower the temperature of the gas inlet part and to increase the temperature of the gas outlet part, it is preferable to combine the cooling water and the direction in which the gas flows. With such a configuration, it is possible to smoothly discharge the generated water generated in large quantities near the outlet. In other words, when the flow direction of the gas changes, the correlation with the temperature distribution is broken, and the water is more likely to be clogged.

Here, in the present embodiment, as in Example 1, the separator is configured as shown in FIG. 1, and the battery is installed so as to be arranged as shown in FIG. According to this embodiment, even when the gas flow paths are switched in parallel, since the flow direction of the gas does not change, flooding is always suppressed and stable operation is possible.

FIG. 8 shows changes in the voltage over time when the battery was operated under the same conditions as in Example 1 under a load of 1/2 at rated time. In FIG. 8, the comparative example 3 also shows the characteristic when the inlet and outlet of a 2nd gas flow path were forcibly reversed, and gas was flowed in the direction against gravity. It can be seen from FIG. 8 that the gas can be flowed in a direction that does not always counter gravity, thereby enabling easy and reliable operation.

<Embodiment 3>

9 and 10 show a cathode-side separator 10A and an anode-side separator 20A for constituting cell A. As shown in FIG. The separator 10A has manifold holes 11A, 13A and 15A of the oxidant gas and manifold holes 12A, 14A and 16A of the fuel gas, and the manifold holes 11A and 15A on the surface facing the cathode. Has a gas flow passage 17A corresponding to the oxidant gas unit flow passage of the present invention. On the other hand, the separator 20A has the manifold holes 22A, 24A and 26A of the fuel gas and the manifold holes 21A, 23A and 25A of the oxidant gas, and the manifold holes 22A and the surface facing the anode. A gas flow path 28A corresponding to the fuel gas unit flow path of the present invention connecting 26A) is provided.

11 and 12 show a cathode side separator 10B and an anode side separator 20B for constituting the cell B. As shown in FIG. The separator 10B has manifold holes 11B, 13B, and 15B of oxidant gas and manifold holes 12B, 14B, and 16B of fuel gas, and the manifold holes 13B and 15B on the surface facing the cathode. Has a gas flow passage 17B corresponding to the oxidant gas unit flow passage of the present invention. On the other hand, the separator 20B has the manifold holes 22B, 24B and 26B of the fuel gas and the manifold holes 21B, 23B and 25B of the oxidant gas, and the manifold holes 24B and the surface facing the anode. It has a gas flow path 28B corresponding to the fuel gas unit flow path of the present invention connecting 26B). Here, the gas flow path 17A and the gas flow path 17B are formed in all of the oxidant gas flow path grooves of the present invention, and the gas flow path 28A and the gas flow path 28B are formed in the fuel gas flow path grooves of the present invention. It is formed in all.

The electrolyte membrane electrode assembly (MEA) combined with the separator includes a polymer electrolyte membrane having the same size as the separator, a pair of gas diffusion electrodes sandwiching the electrolyte membrane, that is, a portion pushed out from the peripheral edge of the cathode and the anode and the electrode. It consists of a pair of gaskets fitted with an electrolyte membrane.

This MEA is sandwiched between the separators 10A and 20A to form a cell A. Similarly, the MEA is sandwiched between the separators 10B and 20B to form a cell B.

The cell A and the cell B are alternately stacked to form a cell stacked body.

FIG. 17 shows a polymer electrolyte fuel cell using the cell laminate. The cell laminated body 130 is fitted to the end plate 133 through the current collector plate 131 and the insulating plate 132 at both ends thereof, and fastened by bolts (not shown). One end plate communicates with the manifold 101 and the oxidant gas manifold holes 13A, 13B, 23A, and 23B which are connected to the oxidant gas manifold holes 11A, 11B, 21A, and 21B of the separator. Manifolds 3L connected in succession to the manifold holes 12A, 12B, 22A, and 22B for fuel gas, and in turn communicates with manifold holes 14A, 14B, 24A, and 24B for fuel gas. The manifold 4L is attached. The other end plate communicates with the manifold 3R, which communicates with the oxidant gas manifold holes 13A, 13B, 23A, and 23B, and the fuel gas manifold holes 14A, 14B, 24A, and 24B. Manifold 4R, a manifold 105 in communication with the oxidant gas manifold holes 15A, 15B, 25A, and 25B, and a manifold in communication with the fuel gas manifold holes 16A, 16B, 26A, and 26B. Fold 106 is attached.

A method of supplying oxidant gas and fuel gas when operating the polymer electrolyte fuel cell will be described.

First, when operating at rated power, both oxidant gas and fuel gas are supplied to cells A and B in parallel to generate power. That is, the manifold 3R is closed and the oxidant gas is equally supplied to the manifold 101 and the manifold 3L. As a result, the oxidant gas flows through the gas flow passage 17A through the manifold hole 11A and discharges from the manifold hole 15A as shown by the arrow shown in FIG. 9. Similarly, the oxidant gas flows into the separator 10B through the gas flow passage 17B from the manifold hole 13B and discharges from the manifold hole 15B as shown by the arrow shown in FIG. 11. That is, the gas flow passage 17A and the gas flow passage 17B are connected in parallel, so that the oxidant gas is simultaneously supplied to the two flow passages.

On the other hand, if the manifold 4R is closed and fuel gas is equally supplied to the manifold 102 and the manifold 4L, the separator 20A will have the fuel gas as shown by the arrow shown in FIG. The gas flow path 28A flows from the hole 22A and is discharged from the manifold hole 26A. Similarly, the fuel gas flows into the separator 20B as shown by the arrow shown in FIG. 12 from the manifold hole 24B through the gas flow path 28B, and is discharged from the manifold hole 26B. That is, the gas flow path 28A and the gas flow path 28B are connected in parallel, and fuel gas is supplied to two flow paths simultaneously.

As described above, the oxidant gas and the fuel gas are respectively supplied in parallel to the cathode and the anode of the cell A and the cell B to generate electricity.

Next, when operating at a load of 1/2 of the rated value, the manifold holes 3L, 4L, 5, and 6 are closed, the oxidant gas is supplied to the manifold 101, and the fuel gas is supplied to the manifold 102. To supply. As described below, the oxidant gas and the fuel gas flow in series with the cells A and B, respectively, and are discharged from the manifolds 3R and 4R.

As shown by the arrow of FIG. 13, the oxidant gas supplied to the manifold 101 flows through the gas flow path 17A from the manifold hole 11a of the separator 10A, and is discharged | emitted to the manifold hole 15A. . Next, as shown by the arrow of FIG. 15, it enters the manifold hole 15B of the separator 10B, flows through the gas flow path 17B, and is discharged from the manifold hole 13B. That is, the gas flow passage 17A and the gas flow passage 17B are connected in series, and the oxidant gas is sequentially supplied to the two flow passages.

Similarly, the fuel gas supplied to the manifold 102 flows through the gas flow path 28A from the manifold hole 22A of the separator 20A to the manifold hole 26A, as shown by the arrow of FIG. Discharged. Next, as shown by the arrow of FIG. 16, it enters the manifold hole 26B of the separator 20B, flows through the gas flow path 28B, and is discharged | emitted from the manifold hole 24B. That is, the gas flow path 28A and the gas flow path 28B are connected in series, and the fuel gas is sequentially supplied to the two flow paths.

In the polymer fuel cell of the present embodiment, at least two of the inlet manifold holes among the pair of manifold holes provided in the separator, the supply of gas to the manifold holes is appropriately changed, so that the low-load operation The degradation or instability of the battery performance is avoided.

That is, at least two types of separator pairs in which an electrolyte membrane electrode assembly (MEA) including a polymer electrolyte membrane and an anode and a cathode sandwiching the same are sandwiched are prepared. A cell stack comprising a cell A fitted to the first separator pair and a cell B fitted to the second separator pair is constructed, gas is supplied to the cell A from the first inlet manifold hole, and the cell B is supplied to the second manifold. Supply gas from the hole. Thereby, gas can be supplied to cell A and cell B in parallel. In addition, when the outlet manifold holes of the cell A and the cell B are connected in series, and gas is supplied from the first inlet manifold hole, the gas flows in the cell A and the cell B in series and the second inlet manifold Ejected from the hole.

In this way, one, preferably both, of the oxidant gas and the fuel gas can be supplied in parallel or in series with the cells A and B, depending on the load, and the gas flow rate in the gas flow path can be kept constant regardless of the load. have. As a result, it is possible to avoid deterioration of battery performance or unstable phenomenon during low load operation.

In the structure of a conventional polymer electrolyte fuel cell separator, each gas of fuel gas and oxidant gas is supplied from one gas inlet manifold to the gas passage of the separator and discharged through one gas outlet manifold. It was a composition. In order to increase the commercialization of the fuel cell power generation system, it is required to vary the load of the fuel cell in accordance with electric power demand without lowering the generation efficiency. For this purpose, when the load is increased with respect to the rated output, the flow rate of fuel gas and oxidant gas is increased at a flow rate suitable for that, and when the load is decreased with respect to the rated output, It is desirable to be able to operate by reducing the flow rate.

Usually, the gas flow path provided in the electroconductive separator used for a fuel cell is designed so that it may become the most suitable gas flow rate in a rated output. Therefore, when the electric power load is increased, the gas flow rate in the gas flow path increases with the increase of the gas flow rate, and when the electric power load is reduced, the gas flow rate in the gas flow path decreases as the gas flow rate decreases. When the gas flow rate in the gas flow path increases, the pressure loss of the supply gas increases, so that the power generation efficiency decreases slightly due to the increase in auxiliary machinery power, but the gas flow rate in the gas flow path increases, so that the gas flow rate in the separator gas flow path increases. The dew condensation water and the generated water can be removed efficiently, so that no flooding phenomenon occurs. However, in the case of reducing the power load, the gas flow rate in the gas flow path decreases with the decrease in the gas flow rate. When the gas flow rate in the gas flow path is decreased, it is difficult to efficiently remove condensation water and generated water in the gas flow path of the separator due to the degree of decrease in the flow rate, and a flooding phenomenon occurs. At this time, even if the power load is reduced, if the supply gas flow rate is not reduced, the ratio of the auxiliary machinery power to the power generation output is relatively large, and the power generation efficiency of the power generation system as a whole is lowered.

As described above, the present invention provides a polymer electrolyte fuel cell in which gas supply to a cell having a different inlet manifold hole is switched in series and in parallel through a manifold, so that flooding does not occur, especially during low load operation. To realize that. For example, when the ratio between the highest load generation output and the lowest load generation output is two to one, two gas inlet side manifolds are provided, and the cell A and the second manifold of the gas flow path connected to the first manifold are provided. The cells B connected to the folds are alternately stacked. At the time of high load power generation, gas is supplied in parallel to the first and second gas inlet side manifolds. In addition, the gas is supplied from the first gas inlet manifold at the minimum load operation, the second gas inlet manifold is used as the outlet, and the manifold which is the outlet at high load power generation is closed using a pipe outside the separator. Thereby, the cells are supplied in series and gas is supplied. As a result, the same gas flow rate can be maintained in all gas flow paths even during load fluctuations.

When the gas flow paths are connected in series, each gas flow path is connected to an independent manifold hole by using a pipe from outside the separator, whereby condensed water condensed at the intermediate manifold hole can be discharged to the outside of the separator. Since condensed water is not supplied to the downstream flow path, more stable operation is possible.

In addition, by inserting a mist trap into the connection portion of the manifold hole, it becomes possible to more surely discharge the condensate. At this time, cells in series through the manifold are preferably arranged adjacent to each other.

By these means, it is possible to realize a polymer electrolyte fuel cell in which flooding does not occur, especially during low load operation.

In the case of the high load operation, as described above, the direction of the gas flowing through each gas flow path is a direction that does not reverse to gravity, so that the occurrence of flooding is further suppressed. However, at the time of low load operation, as shown to FIG. 15, 16, the direction of the gas which flows through each gas flow path may contain the direction which goes against gravity. Therefore, in the sense, there is a possibility that flooding may occur, but in the actual system operation situation, since the operation time at the rated load is longer than the operation time at the partial load as described above, this is not a problem level.

In addition, in description of this embodiment, although it is the structure which laminates cell A and the cell B, and two types of cells, three or more types of cells may be laminated | stacked. That is, at the rated load, the gas is simultaneously input to the gas unit flow paths formed in each cell, and at the partial load, at least one of each gas unit flow path is connected in series according to the magnitude of the load, and gas is sequentially input. good.

At this time, when the oxidant gas unit flow paths are connected in series, other than the inlet oxidant gas manifold connected to the inlet of the oxidant gas flow path groove and the outlet oxidant gas manifold connected to the outlet of the oxidant gas flow path groove, The inlet oxidant gas manifold and the outlet oxidant gas manifold in each oxidant gas unit flow path may be connected. When the fuel gas unit flow paths are connected in series, each of the fuel gas manifolds other than the inlet fuel gas manifold connected to the inlet of the fuel gas channel groove and the outlet fuel gas manifold connected to the outlet of the fuel gas channel groove is The inlet fuel gas manifold and the outlet fuel gas manifold in the fuel gas unit flow passage may be connected.

<Embodiment 4>

The overall structure of the polymer electrolyte fuel cell in the present embodiment is shown in FIG. The part different from Embodiment 3 is a valve provided in the piping of each manifold. The inlet manifold 101 and manifold 3L of the oxidant gas are connected to one oxidant gas supply pipe through valves V2 and V1, respectively. The valve V5 is provided in the inlet manifold 3R of the oxidant gas, and the valve V8 is provided in the outlet manifold 105, respectively. The inlet manifold 102 and the manifold 4L of the fuel gas are connected to one fuel gas supply pipe through valves V4 and V3, respectively, and the valve V6 is connected to the inlet manifold 4R of the fuel gas. ), The valve V7 is provided at the outlet manifold 106, respectively. Each valve is connected to the controller 300.

According to this configuration, when the oxidant gas is supplied to the cells A and B in parallel, the controller 300 opens the valves V1, V2 and V8 and simultaneously closes the valve V5, and the manifold 101 and the manifold. The oxidant gas is supplied from the fold 3L, respectively, and discharged from the manifold 105. Similarly, the valves V3 and V4 and V7 are opened, the valve V6 is closed, and the fuel gas is supplied from the manifold 102 and the manifold 4L and discharged from the manifold 106.

On the other hand, when supplying the oxidant gas to the cells A and B in series, the controller 300 opens the valves V2 and V5, closes the valves V7 and V8, and supplies the oxidant gas from the manifold 101. And discharge from the manifold 3R. In addition, the valve V4 and the valve V6 are opened, the valve V3 and the valve V7 are closed, the fuel gas is supplied from the manifold 102, and discharged from the manifold 4R. In this way, in accordance with the change in the power generation output, the parallel connection and the series connection to each gas channel are changed to maintain the gas velocity at which water does not stay in each gas channel.

In above-mentioned Embodiment 3, 4, although each separator used a single thing, it can also be set as the separator which one side functions as a cathode side separator, and the back side functions as an anode side separator. For example, when cell A and cell B are arranged adjacently, the back surface of the cathode side separator of cell A is made into the anode side separator of cell B. As shown in FIG. In addition, in said embodiment, the manifold hole of the cooling water for cooling a cell is abbreviate | omitted for convenience of description. The cooling unit is usually formed by forming a flow path of cooling water on a surface of the cathode separator and the anode separator facing each other. This cooling unit is provided for each cell or every 2 to 3 cells.

(Example 4)

Hereinafter, the Example corresponding to Embodiment 3, 4 is demonstrated.

The acetylene black carbon powder was loaded with 25% by weight of platinum particles having an average particle diameter of about 30 kPa. This was used as a catalyst for the cathode. In addition, 25 weight% of platinum-ruthenium alloy particles with an average particle diameter of about 30 kPa were supported on the acetylene black carbon powder. This was used as a catalyst for the anode. The isopropanol dispersion of these catalyst powders was mixed with ethyl alcohol dispersion of perfluorocarbon sulfonic acid powder to obtain a paste state. Using these pastes as a raw material, the screen printing method was used to apply and dry one surface of a carbon nonwoven fabric having a thickness of 250 µm to form a cathode catalyst layer and an anode catalyst layer, respectively. The amount of platinum contained in the obtained catalyst layer was 0.3 mg / cm ² and the amount of perfluorocarbon sulfone was 1.2 mg / cm ² .

As for the electrode which consists of carbon nonwoven fabric which has these catalyst layers, the structure other than a catalyst material is the same in both a cathode and an anode cathode. These electrodes were joined by hot press to both surfaces of the central portion of the hydrogen ion conductive polymer electrolyte membrane having an area larger than the electrode so that the printed catalyst layer was in contact with the electrolyte membrane side. Furthermore, the gasket which cut out the sheet | seat of the 250-micrometer-thick elastomer (Biton AP of Dupont, hardness 500) to predetermined size is arrange | positioned on both surfaces of the electrolyte membrane which exposes from the outer periphery of the above-mentioned electrode, and is bonded by hot press. Integral and thus, MEA was produced. As the hydrogen ion conductive polymer electrolyte, a thin membrane of perfluorocarbonsulfonic acid having a thickness of 30 µm was used.

In this embodiment, the separators 10A, 10B, 20A, and 20B shown in Figs. 9 to 12 were used. These separators formed gas flow paths and manifold holes by machining on an isotropic graphite plate having a thickness of 3 mm. The groove width of the gas flow path was 2 mm, the depth was 1 mm, the width of the ribs between the gas flow paths was 1 m, and the gas flow paths were all one pass.

Cell A, in which the cathode-side separator 10A and the anode-side separator 20A are combined with the MEA, and cell B, in which the cathode-side separator 10B and the anode-side separator 20B are combined with each other, are alternately stacked. The cell stack of the cell was constructed. The cell laminated body was sandwiched by a stainless steel end plate through a current collector plate made of gold plated copper plate and an insulating plate made of polyphenylene sulfide, and both end plates were fastened with a fastening rod. The clamping pressure was 10 kgf / cm ² per electrode area. Moreover, as shown in each figure, the laminated battery was comprised so that the upper part of a separator might turn up.

Next, the actual operation method of the battery using this cell laminated body is demonstrated. As described in the above embodiment, when the battery was operated under the rated conditions, both the oxidant gas and the fuel gas were supplied to the cells A and B in parallel. In the low load operation of 50% or less with respect to the rating, the oxidant was supplied in series to the cells A and B, and the fuel gas was also supplied to the cells A and B in series. The rated operating conditions of this battery are 75% fuel utilization, 40% oxygen utilization, and 0.3 A / cm ² current density.

The polymer electrolyte fuel cell was maintained at 70 ° C., and a humidified and heated hydrogen main gas (80% hydrogen gas / 20% carbon dioxide / 10 ppm carbon monoxide) was heated at 70 ° C. to the anode, and a dew point of 70 ° C. was applied to the cathode. Humidified and warm air was supplied, respectively. The current-voltage characteristics were evaluated by varying the current density from 0.075 A / cm ^{2 at} a low load of 25% of the rated voltage to 0.3 A / cm ² at a rated load. However, the utilization during the test was equal to the rated condition. The result is shown in FIG. 19, the characteristics of the conventional polymer electrolyte fuel cell, that is, a cell in which only cell A is stacked are also described for comparison. In this embodiment, in the case of a current density of 0.15A / cm ² or less is converted into a serial flow path, 0.15A / cm ² or more, the test was converted to a parallel flow path. From FIG. 19, in the polymer electrolyte fuel cell according to the present embodiment, flooding occurs due to a decrease in gas flow rate in a conventional battery, and flooding does not occur even near 0.075 A / cm ² , which is difficult to operate. You can see that it is driving. In this embodiment, two kinds of cells are used, but it is also possible to increase the number of cells connected in series by increasing the manifold.

(Example 5)

In this example, a valve is provided in the pipe as in the fourth embodiment. By opening and closing the valve, the gas supply was switched to perform the same test as in Example 1. As a result, the performance equivalent to Example 1 was obtained.

In addition, in the above description, in an actual system, a humidifier is connected to the inlet of each gas flow path, and a waste heat exchanger may be connected to the outlet of each gas flow path.

In addition, in the above description, the installation direction of each separator and each cell shown in each drawing is the same as the direction shown in FIG.

The polymer electrolyte fuel cell and the operation method thereof according to the present invention can suppress the occurrence of flooding at low load and are useful as a fuel cell cogeneration system or the like.

Claims (9)

An anode-side separator having a polymer electrolyte membrane, an anode and a cathode sandwiching the polymer electrolyte membrane, a cathode side separator having an oxidant gas flow groove for supplying an oxidant gas to the cathode, and a fuel gas flow groove for supplying fuel gas to the anode; It has a cell laminated body laminated | stacked the excitation cell, A part or all of the oxidant gas flow path grooves form an oxidant gas unit flow path which is a flow path from the input to the cathode side separator to the output. A part or all of the fuel gas flow path grooves form a fuel gas unit flow path, which is a flow path from the anode side separator to the output, Two or more of the oxidant gas unit flow paths in the cell stacked body can be connected in parallel or in series, A polymer electrolyte fuel cell in which two or more of said fuel gas unit flow paths in said cell stack are connected in parallel or in series. 2. The flow rate of the oxidant gas passing through the oxidant gas flow path groove maintains the speed at which water does not stay in the oxidant gas flow path groove and changes through the fuel gas flow path groove. And the parallel connection or the series connection is changed so that the speed of the fuel gas is maintained so that water does not stay in the fuel gas flow path groove. The oxidant gas unit flow path is formed in a part of the oxidant gas flow path groove, and the fuel gas unit flow path is formed in a part of the fuel gas flow path groove. In the case of being connected in parallel, the plurality of oxidant gas unit flow paths formed in the cathode side separators are connected in parallel to each other so that the oxidant gas is supplied at the same time, and the plurality of fuels formed in the anode side separators. Gas unit flow passages are connected in parallel to each other so that the fuel gas is supplied at the same time, When connected in series, all or part of the plurality of oxidant gas unit flow paths formed in each of the cathode side separators are connected to each other in series so that the oxidant gas is supplied in turn, and is formed in each of the anode side separators. All or a part of the plurality of fuel gas unit flow paths that are present, the polymer electrolyte fuel cell is connected in series with each other so that the fuel gas is sequentially supplied. The oxidant gas unit flow path is formed in all of the oxidant gas flow path grooves, and the fuel gas unit flow path is formed in all of the fuel gas flow path grooves. When connected in parallel, the oxidant gas unit flow paths formed in the cathode-side separators are connected in parallel so that the oxidant gas is supplied simultaneously, and the fuel gas unit flow paths formed in the anode-side separators are connected to each other. Are connected in parallel to each other so that the fuel gas is supplied at the same time, In the case of being connected in series, all or part of the oxidant gas unit flow path formed in each of the cathode-side separators are connected in series so that the oxidant gas is sequentially supplied, and the fuel formed in each of the anode-side separators. A polymer electrolyte fuel cell in which all or part of gas unit flow passages are connected in series to each other so that the fuel gas is sequentially supplied. The oxidant gas manifold according to claim 3 or 4, wherein the inlet oxidant gas manifold connected to the inlet of each of the oxidant gas unit flow passages, the outlet oxidant gas manifold connected to the outlet of each of the oxidant gas unit flow passages, An inlet fuel gas manifold connected to the inlet of the fuel gas unit flow passage, and an outlet fuel gas manifold connected to the outlets of the respective fuel gas unit flow passages, When the oxidant gas unit flow paths are connected in series, other than the inlet oxidant gas manifold connected to the inlet of the oxidant gas flow path groove and the outlet oxidant gas manifold connected to the outlet of the oxidant gas flow path groove, The inlet oxidant gas manifold and the outlet oxidant gas manifold, When the fuel gas unit flow paths are connected in series, other than the inlet fuel gas manifold connected to the inlet of the fuel gas flow path groove and the outlet fuel gas manifold connected to the outlet of the fuel gas flow path groove, A polymer electrolyte fuel cell in which an inlet fuel gas manifold and an outlet fuel gas manifold are connected. 6. The polymer electrolyte according to claim 5, wherein the oxidant gas unit flow paths and the fuel gas unit flow paths are connected in series or in parallel by opening and closing a valve provided outside the lamination cell in accordance with the power generation power. Fuel cell. 6. An inlet oxidant gas manifold and an outlet according to claim 5, except for an inlet oxidant gas manifold connected to an inlet of the oxidant gas flow path groove and an outlet oxidant gas manifold connected to an outlet of the oxidant gas flow path groove. Inlet fuel other than the portion to which the oxidant gas manifold is connected, and the inlet fuel gas manifold connected to the inlet of the fuel gas flow path groove and the outlet fuel gas manifold connected to the outlet of the fuel gas flow path groove. A polymer electrolyte fuel cell in which a mist trap is installed at a portion where a gas manifold and an outlet fuel gas manifold are connected. The parallel connection between the oxidant gas unit flow paths is made so that the direction in which the oxidant gas flows does not run against gravity. The parallel connection between the fuel gas unit flow paths is such that the direction in which the fuel gas flows is a direction that does not counter gravity. A cell having a polymer electrolyte membrane, an anode and a cathode sandwiching the polymer electrolyte membrane, a cathode side separator having an oxidant gas flow path for supplying an oxidant gas to the cathode, and an anode side separator having a fuel gas flow path for supplying fuel gas to the anode Having a stacked cell stack, A part or all of the oxidant gas flow path grooves form an oxidant gas unit flow path which is a flow path from the input to the cathode side separator to the output. A part or all of the fuel gas flow path grooves is a method of operating a polymer electrolyte fuel cell in which a fuel gas unit flow path, which is a flow path inputted to the anode side separator and then outputted, is formed. Connecting two or more of the oxidant gas unit flow paths in the cell stacked body in parallel or in series; A method of operating a polymer electrolyte fuel cell comprising the step of connecting two or more of said fuel gas unit flow paths in said cell stack in parallel or in series.