JP2009123446A - Solid polymer fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain corrosion of a collecting plate in a simple structure. <P>SOLUTION: A solid polymer fuel cell so made to have supply and exhaustion of cathode gas, anode gas, and cooling water made from one end side of a cell stack 1 in a lamination direction, by making a distribution system of the cathode gas, the anode gas, and the cooling water to the stack 1 in a countercurrent form (a U-shape) has a conductive platy matter 14 without hole processing or recessing made having a plane shape similar to that of separators 8a, 8b intercalated between unit cells 2 at end parts of the other end in the lamination direction and another-end side collector plate 3d arranged outside them. By having the conductive platy matter 14 inhibit contact of the cathode gas, the anode gas, and the cooling water supplied to and circulated in each unit cell 2 of the stack 1 with the other-end side collector plate 3d, fear of corrosion generated at the other-end side collector 3d is prevented. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polymer electrolyte fuel cell capable of suppressing corrosion of a current collector plate.

  A fuel cell is expected to be an effective power generation device because it has higher thermal efficiency and less environmental pollution than other power generation methods using fuel. In particular, the polymer electrolyte fuel cell (PEFC) generates power at a low temperature of 100 ° C. or lower, and has a high output density. Therefore, the polymer electrolyte fuel cell (PEFC) can be reduced in size as compared with other types of fuel cells. In recent years, it has been used as a power generator for small-scale business use or home use because it has advantages such as little deterioration and easy start-up.

  The general structure of the polymer electrolyte fuel cell is as follows. That is, an MEA (membrane / electrode assembly) is formed by sandwiching both surfaces of a solid polymer electrolyte membrane having proton conductivity as an electrolyte between both cathode (air electrode) and anode (fuel electrode) gas diffusion electrodes. A single cell is configured by arranging a separator having a gas flow path on the inner surface side and a cooling water flow path on the outer surface side on both sides of the MEA.

  Further, as shown in FIG. 2, the required number of single cells 2 having the above-described structure are stacked, and current collecting plates 3 and electrical insulating plates 4 are arranged in order from the inside on both sides of the stack of single cells 2, With a pair of end plates (holders) 5 arranged on the outside, the end plates 5 are fastened to each other with fastening bolts 6 and nuts 7 that are interposed with required fastening means (not shown) such as a disc spring. The solid polymer type fuel cell stack 1 is configured by fixing.

  Although not shown, the anode gas is supplied to the anode separator gas passage, the cathode gas is supplied to the cathode separator gas passage, and the cooling water is supplied to the cooling water passage of each separator. Supply is made for the anode gas, the cathode gas, and the cooling water, which are formed by connecting holes provided in the outer peripheral portions of the cathode side and anode side separators so as to communicate with each other in the cell stacking direction. This is done through each internal manifold.

  By the way, in general, in order to maintain high proton conducting performance of the solid polymer electrolyte membrane used in the solid polymer fuel cell, it is necessary to keep the solid polymer electrolyte membrane in a wet state. The gas and cathode gas are supplied to each single cell 2 in a humidified state.

  Therefore, in each current collector plate 3 provided at both ends in the cell stacking direction of the stack 1 of the polymer electrolyte fuel cell, a predetermined gas flow path provided in the separator of the single cell 2 adjacent to the inside thereof is provided. Corrosion occurs due to the formation of local batteries due to the moisture in the anode gas or cathode gas at locations where the anode gas or cathode gas that is to be circulated contacts or where the anode gas or cathode gas that is circulated through the internal manifold contacts. It will occur. Further, at the current collector plate 3, a location where the cooling water flowing through the cooling water flow path provided in the separator of the single cell 2 adjacent to the inside of the current collector plate 3 contacts, or a location where the cooling water flowing through the internal manifold contacts. In fact, local batteries are formed due to various ions contained in the cooling water, resulting in corrosion. Therefore, it has been desired to suppress the corrosion of the current collector plate 3 as described above.

  As a means for suppressing the corrosion of the current collector plate 3 in the polymer electrolyte fuel cell, for example, as shown in FIG. 3, the cathode is formed at one end in the cell stacking direction of the stack 1 of the polymer electrolyte fuel cell. The cathode separator 8a of the single cell 2 adjacent to the inside of the side current collector 3a is provided with a flow path 10 for oxidant gas (cathode gas) on the side facing the MEA 9, while the cathode side current collector 3a has The contact surface is a flat surface, and the anode side separator 8b of the single cell 2 adjacent to the inside of the anode side current collector plate 3b at the other end of the stack 1 in the cell stacking direction faces the MEA 9. A side surface is provided with a flow path 11 for fuel gas (anode gas), while the surface in contact with the anode-side current collector plate 3b is a flat surface. By preventing the cooling water flow path from being formed between the separators 8a and 8b adjacent to the inner side of the separator, it is possible to prevent the cooling water from coming into contact with the current collector plates 3a and 3b. Has been proposed.

  Furthermore, at both ends in the cell stacking direction in the stack 1 of the polymer electrolyte fuel cell, the electric current is formed inside the through holes 13 provided in the end plates 5, the electric insulating plates 4, and the current collecting plates 3a and 3b. It has also been considered that the current collector plates 3a and 3b can be prevented from contacting the oxidant gas and the fuel gas by inserting a cylindrical manifold member 12 made of an insulating material. . In FIG. 3, the same components as those shown in FIG. 2 are denoted by the same reference numerals. (For example, refer to Patent Document 1).

  In general, as a method of distributing the cathode gas, the anode gas and the cooling water to the stack 1 of the fuel cell having the laminated structure of the single cells 2, as shown in FIG. The supply direction and the discharge direction of the cooling water are reversed by 180 degrees so that the cathode gas, the anode gas and the cooling water are supplied and discharged only at one end side in the cell stacking direction in the stack 1 of the fuel cell. As shown in FIG. 4 (b), the supply direction and discharge direction of cathode gas, anode gas and cooling water are the same as shown in FIG. A normal flow type (Z-type) system is generally adopted in which cooling water is supplied to either one of the cell stacking directions to the fuel cell stack 1 and discharged to the other. Are (e.g., see Patent Document 2).

JP 2006-12669 A JP-A-10-199552

  However, in order to employ the means shown in Patent Document 1 in order to prevent corrosion of the current collector plate in the polymer electrolyte fuel cell, the inside of the cathode side current collector plate 3a located at both ends in the cell stacking direction is used. The contact surface between the cathode separator 8a of the single cell 2 adjacent to the anode side separator 8b and the anode side separator 8b of the single cell 2 adjacent to the inside of the anode side current collector plate 3b is flat. As a configuration as a surface, a separator having a special shape different from the separator used in the other single cell 2 in the middle part in the cell stacking direction must be used.

  Since carbon separators are usually formed by pressing and compacting carbon powder with a mold, a set of two sheets corresponding to the shape of both side surfaces of the separator is required. In order to form the separators 8a and 8b used in the single cells 2 arranged at both ends of the stack 1 in the stack 1 in a special shape different from the separators used in the other single cells 2, a dedicated die is separately prepared. There is a problem that must be done.

  Therefore, the present invention is capable of suppressing the corrosion of the current collector plate with a simple configuration without using a separator having a special shape such as a configuration in which a groove serving as a gas channel or a cooling water channel is provided only on one side. An object of the present invention is to provide a polymer electrolyte fuel cell.

  In order to solve the above-mentioned problems, the present invention provides a cathode gas, an anode gas and a cooling water supply to the stack in a counter-flow manner corresponding to claim 1. In a polymer electrolyte fuel cell that is configured to be discharged from one end of the stack in the cell stacking direction, a single cell at the other end of the cell stacking direction and the other end current collector disposed outside the cell It is set as the structure formed by incorporating a conductive plate-like material between the plates.

  In addition, the conductive plate-like material in the above configuration is configured to have a planar shape similar to a separator formed by sandwiching an MEA in a single cell.

  Further, the conductive plate-like material in each of the above configurations is made of a material similar to that of the separator formed by sandwiching the MEA in a single cell.

  In each of the above-described configurations, the other end side current collector plate is a cathode side current collector plate.

According to the polymer electrolyte fuel cell of the present invention, the following excellent effects are exhibited.
(1) The cathode gas, anode gas and cooling water distribution system to the stack is made into a counter-flow type, and cathode gas, anode gas and cooling water are supplied and discharged from one end side of the stack in the cell stacking direction. In the polymer electrolyte fuel cell, a conductive plate-like material is interposed between the single cell at the other end on the other side in the cell stacking direction and the other current collector on the other end. The cathode gas, anode gas, and cooling water, which are configured to cause the stack to be supplied and discharged from one end side in the cell stacking direction, are formed by the conductive plate-like material. The possibility of contact with the other end side current collector plate provided on the other end side of the stack in the cell stacking direction can be prevented. Therefore, it is possible to surely prevent the other end side current collecting plate from being corroded by local batteries due to moisture in the cathode gas or anode gas or various ions contained in the cooling water. it can.
(2) The effect of the above (1) is that a conductive plate-like object that is a simple plate is interposed between a single cell at the other end of the stack in the cell stacking direction and the current collector plate at the other end. Can be obtained by a simple configuration. In addition, the conductive plate-like material can be easily manufactured because neither drilling nor grooving is required. Therefore, corrosion of the current collector plate on the other end side can be prevented without the need for a specially shaped separator in which a groove serving as a gas flow path or a cooling water flow path is provided only on one side, and a solid polymer fuel cell As a whole, it is possible to suppress corrosion occurring in the current collector plate.
(3) By adopting a configuration in which the conductive plate-like material has a planar shape similar to the separator formed by sandwiching the MEA with a single cell, the single cell at the other end side in the cell stacking direction in the stack, The conductive plate-like object can be easily incorporated between the other end side current collector plate and between the single cell at the other end side end portion in the cell stacking direction and the other end side current collector plate in the stack. The risk that the cross-sectional area of the path through which the current flows changes to affect the battery performance can be prevented.
(4) By adopting a structure in which the conductive plate-like material is made of the same material as the separator formed by sandwiching the MEA with a single cell, a single cell at the other end side in the cell stacking direction in the stack, and the like High conductivity can be ensured between the end-side current collector plate, and the conductive plate-like object is interposed between the single cell at the other end in the cell stacking direction and the other end-side current collector plate. It is possible to prevent the possibility that the performance will deteriorate.
(5) By adopting a configuration in which the other end side current collector plate is a cathode side current collector plate, the entire polymer electrolyte fuel cell is advantageous in reducing the absolute amount of corrosion generated on the current collector plate. It can be.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 shows an embodiment of a polymer electrolyte fuel cell according to the present invention. The distribution system of cathode gas, anode gas and cooling water to the stack 1 is defined as a countercurrent type (U type), In the polymer electrolyte fuel cell in which supply and discharge of anode gas and cooling water are all performed from one end side (the right side in the figure) of the stack 1 in the cell stacking direction, the other end part in the cell stacking direction (see FIG. The upper left end) has a planar shape similar to that of the separators 8a and 8b between the single cell 2 on the other end side and the other end side current collecting plate 3d arranged on the outer side, and for cathode gas, anode gas or cooling A conductive plate-like object 14 that is not subjected to groove processing on the surface for forming a water flow path and hole processing to correspond to the internal manifold is incorporated so as to be interposed.

  More specifically, the stack 1 is formed by sandwiching both surfaces of a proton-conducting solid polymer electrolyte membrane between gas diffusion electrodes of a cathode (air electrode) and an anode (fuel electrode). A single cell 2 is configured by arranging separators 8a and 8b each having a gas flow path 10 or 11 on the inner surface side and a cooling water flow path 15 on the outer surface side on both sides of the electrode assembly 9). The required number of cells 2 are stacked.

  Further, in the laminated body of the single cells 2, the holes provided in the outer peripheral portions of the separators 8 a and 8 b of the single cells 2 are connected in the cell stacking direction to supply and discharge the cathode gas. The internal manifolds 16 for supplying and discharging the cooling water and for supplying and discharging the cooling water are formed. In FIG. 1, for convenience of illustration, only the internal manifold 16 for supplying and discharging one of the cathode gas and the anode gas is shown.

  On one end side (right side in the figure) of the laminate of the single cells 2 is an internal manifold 16 for cathode gas, anode gas, and cooling water provided in the laminate of the single cells 2. One end side current collecting plate 3c for one end side in the cell stacking direction, which is provided with through holes 17 for communicating with the respective internal manifolds 16 at corresponding positions, and an electric insulating plate 4a are sequentially arranged from the inside, Furthermore, on the outside, each of the cathode gas supply and discharge, anode gas supply and discharge, cooling water supply and discharge corresponding to the internal manifold 16 for cathode gas, anode gas and cooling water, respectively. One end side end plate 5a having a fluid flow path 18 is disposed. In FIG. 1, for convenience of illustration, only the supply and discharge flow path 18 of one of the cathode gas and the anode gas is shown.

  On the other end side (left side in the figure) of the laminate of the single cells 2, there is a conductive plate 14 that is not subjected to any hole processing or groove processing, and for the other end side in the cell stacking direction. The other end side current collecting plate 3d and the electric insulating plate 4b are sequentially arranged from the inner side, and the other end side end plate 5b is further arranged on the outer side, and the end plates 5a and 5b on the one end side and the other end side are arranged. The stack 1 is configured by fastening them from the outside by fastening bolts 6 and nuts 7 with fastening means (not shown) interposed therebetween. Thereby, between the laminated body of the said single cell 2 and the other end side current collecting plate 3d distribute | arranged to the other end side of a cell lamination direction, the said flat-plate-like electroconductivity which has not performed the said groove process and hole process The other end-side current collecting plate 3d disposed on the other end side in the cell stacking direction, and the cathode gas, the anode gas, and the like flowing through each single cell 2 in the stack 1 The contact with the cooling water can be completely blocked.

  The conductive plate 14 may be made of a material that has high conductivity and does not cause corrosion by the local battery. Specifically, for example, it may be made of carbon which is the same material as the separators 8a and 8b. As a result, the conductive plate-like object 14 can be easily procured, and the plate-like object 14 can be secured with high conductivity. It is possible to prevent a decrease in battery performance due to the presence of the single cell 2 and the other end side current collector plate 3d.

  In the stack 1, the one end side current collecting plate 3c for one end side in the cell stacking direction is an anode side current collecting plate 3c, and the other end side current collecting plate 3d for the other end side in the cell stacking direction is the cathode side current collecting plate. The plate 3d is desirable. This is because, after operating the conventional polymer electrolyte fuel cell for the required time, the amount of corrosion generated in the current collector plates on the anode side and the cathode side was examined. This is because it has been obtained as a rule of thumb that corrosion is more likely to corrode than the anode current collector. Therefore, the other end side current collecting plate 3d is used as the cathode side current collecting plate 3d, and the contact between the cathode side current collecting plate 3d and the cathode gas, the anode gas and the cooling water is completely cut off. This is because if the 3d corrosion is prevented, the absolute amount of corrosion generated on the current collector plates 3c and 3d can be reduced as the whole polymer electrolyte fuel cell.

  When cathode gas, anode gas, and cooling water are appropriately supplied to the polymer electrolyte fuel cell having the above-described configuration, these three fluids are all disposed on one end side of the stack 1 in the cell stacking direction. After passing through the flow path 18 of the end plate 5a, the electrical insulating plate 4a, and the anode side current collecting plate 3c, it is supplied to each single cell 2 via the supply side internal manifold 16, and thereby, in each single cell 2 A fuel cell reaction is performed, and the anode side current collecting plate 3c provided on one end side in the cell stacking direction of the stack of single cells 2 and the other end side of the stack of single cells 2 in the cell stacking direction are electrically connected. The generated electric power is taken out to an external circuit (not shown) connected to the cathode-side current collecting plate 3d provided via the conductive plate-like material 14. At this time, the heat generated in each single cell 2 by the fuel cell reaction is appropriately cooled by cooling water (not shown).

  Thereafter, the cathode gas and anode gas after being supplied to the fuel cell reaction in each single cell 2 and the cooling water after being supplied to the cooling of each single cell 2 are both exhaust internal manifolds 16. Further, it is discharged to the outside through the anode-side current collecting plate 3c, the electric insulating plate 4a, and the end plate 5a disposed on one end side of the stack 1 in the cell stacking direction.

  Therefore, on the other end side of the stack 1 in the cell stacking direction, even if cathode gas, anode gas, or cooling water comes into contact with the conductive plate 14, the cathode-side current collector plate 3 d provided on the outer side thereof is No contact with the cathode gas, anode gas, or cooling water. Therefore, it is possible to reliably prevent the local battery from corroding the cathode current collector plate 3d.

  If the stack 1 is configured such that the other end side current collecting plate 3d on the other end side in the cell stacking direction of the stack 1 becomes an anode side current collecting plate, the cathode gas and anode of the anode side current collecting plate The contact with the gas and the cooling water can be prevented, and it is possible to reliably prevent the local battery from corroding the other end side current collecting plate 3d as the anode side current collecting plate.

  As described above, according to the polymer electrolyte fuel cell of the present invention, the cathode gas, anode gas, and cooling water distribution system to the stack 1 is changed to the counterflow type (U shape). The other end side current collector plate 3d provided on the other end side in the cell stacking direction opposite to one end side in the cell stacking direction (the right side in the figure) in the stack 1 that is supplied and discharged is connected to the cathode It is possible to prevent the gas, the anode gas, and the cooling water from coming into contact with each other, and reliably prevent the other end side current collecting plate 3d from being corroded by the local battery.

  The anti-corrosion effect of the other end side current collecting plate 3d is that a simple plate is provided between the single cell 2 at the other end side end portion in the cell stacking direction of the stack 1 and the other end side current collecting plate 3d arranged outside thereof. It can be obtained by a simple configuration in which a certain conductive plate 14 is interposed. Moreover, the conductive plate-like material 14 can be easily manufactured because neither hole processing nor groove processing is required. Therefore, it is possible to prevent corrosion of the other end side current collector plate 3d without requiring a specially shaped separator in which a groove serving as a gas flow path or a cooling water flow path is provided only on one side, and a solid polymer fuel As a whole battery, it is possible to suppress the corrosion of the current collector plates 3c and 3d.

  The present invention is not limited only to the above-described embodiment, but a solid polymer fuel of a type in which the flow system of cathode gas, anode gas and cooling water to the stack 1 is a countercurrent type (U type). In the case of a battery, any type of solid, such as changing the flow path shape of the cathode gas, anode gas, and cooling water in the separators 8a and 8b of each single cell 2 to a shape other than that shown in the figure or changing the flow direction. Needless to say, the present invention can be applied to polymer fuel cells, and various modifications can be made without departing from the scope of the present invention.

1 is a schematic cut-away side view showing an embodiment of a polymer electrolyte fuel cell of the present invention. It is a side view which shows the outline of an example of the conventional polymer electrolyte fuel cell. It is a schematic diagram showing a conventionally proposed means for suppressing corrosion of a current collector plate in a polymer electrolyte fuel cell. FIG. 2 is a schematic diagram showing a distribution method of anode gas, cathode gas, and cooling water for a fuel cell stack, wherein (a) shows a countercurrent type and (b) shows a positive flow type.

Explanation of symbols

1 stack 2 single cell 3d current collector on the other end (cathode current collector)
8a, 8b Separator 9 MEA
14 Conductive plate

Claims (4)

  The cathode gas, anode gas and cooling water distribution system to the stack is a counter-current type, and cathode gas, anode gas and cooling water are supplied and discharged from one end side of the stack in the cell stacking direction. In a polymer type fuel cell, a conductive plate-like material is interposed between a single cell at the other end side end in the cell stacking direction and the other end side current collector plate arranged outside the cell. A polymer electrolyte fuel cell having the structure as described above.   The polymer electrolyte fuel cell according to claim 1, wherein the conductive plate-like material has a planar shape similar to that of a separator formed by sandwiching MEA in a single cell.   The polymer electrolyte fuel cell according to claim 1 or 2, wherein the conductive plate-like material is made of a material similar to that of a separator formed by sandwiching MEA in a single cell.   4. The polymer electrolyte fuel cell according to claim 1, wherein the other end side current collecting plate is a cathode side current collecting plate.

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