JP2005285399A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell which improves a power generation efficiency by making the potential inside a cell surface uniform and prevent local degradation inside the cell surface from occurring. <P>SOLUTION: A fuel cell 1 comprises: a cell laminated body 10 which a plurality of unit cells 11 are laminated to form; gas supply inlets which communicate with the cell laminated body 10 and supply reactant gases to gas passages of the respective unit cells 11; and terminals 12A, 12B which are mounted on the cell laminated body 10; where current output parts 42A, 42B of the terminals 12A, 12B corresponding to the respective gas supply inlets are mounted in the neighborhood of the respective gas supply inlets. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell, and more particularly to a fuel cell with improved power generation efficiency.

  Conventionally, as a general polymer electrolyte fuel cell, an electrolyte membrane composed of an ion exchange membrane, a fuel electrode (anode electrode) composed of a catalyst layer and a diffusion layer disposed on one surface of the electrolyte membrane, and the electrolyte membrane An oxidant electrode (cathode electrode) composed of a catalyst layer and a diffusion layer disposed on the other surface, a membrane electrode assembly (MEA) composed of the catalyst layer and a diffusion layer, and a fuel gas (hydrogen) on the fuel electrode are oxidized. There is a cell that includes a separator having a fluid passage for supplying an oxidant gas (oxygen, usually air) to the agent electrode, and a plurality of such cells are stacked to form a module.

As such a fuel cell, for example, terminal terminals for power extraction are extended along the cell stacking direction from the end surfaces of a pair of terminal plates disposed further outside the single cells located at both ends in the cell stacking direction. By disposing the terminal terminal within a range where the water vapor partial pressure in the oxidant gas flow path is equal to or lower than the saturated water vapor pressure, an increase in electric resistance is suppressed, and a single terminal located at the end of the cell stacking direction is suppressed. There has been proposed one that suppresses a decrease in cell temperature and effectively prevents a decrease in power generation performance of the single cell. (For example, refer to Patent Document 1).
JP 2002-252022 A

  Here, in the fuel cell, since electrons are concentrated near the current extraction portion of the terminal, it is known that the current density in this portion increases. For this reason, in the vicinity of the current extraction portion of the terminal, the potential during power generation is lower than in other portions, the power generation efficiency is lowered, and there is a possibility that local degradation is caused in the cell plane.

  However, in the fuel cell described in Patent Document 1 described above, it is possible to prevent a decrease in power generation efficiency caused by the concentration of electrons and to prevent local deterioration in the cell plane. No proposal has been made.

  An object of the present invention is to improve such a conventional fuel cell. In the cell plane, the electric potential during power generation is made uniform to improve the power generation efficiency, and in the cell plane. An object of the present invention is to provide a fuel cell capable of preventing local deterioration from occurring.

  In order to achieve this object, the present invention provides a cell stack in which a plurality of single cells are stacked, and is provided in communication with the cell stack and supplies a reaction gas to the gas flow path of each single cell. A fuel cell comprising a gas supply port and a terminal provided in the cell stack, and provided with a current extraction portion of a terminal corresponding to the gas supply port in the vicinity of the gas supply port. is there.

  The fuel cell having this configuration is provided with a current extraction portion of the terminal that has a large current density and a low potential during power generation in the vicinity of a gas supply port having a large gas partial pressure in the cell surface and high power generation efficiency. As a result, the potential in the cell plane can be made uniform.

  In the fuel cell according to the present invention, the gas supply port can be provided at a portion where the current density is increased during power generation. Moreover, the current extraction part of the terminal can be provided at a site where the gas partial pressure of the reaction gas is high.

  Further, in the fuel cell according to the present invention, when the gas flow path is a serpentine flow path, it is more preferable that the current extraction part of the terminal is provided near the first turn part of the gas flow path.

  Furthermore, in the fuel cell according to the present invention, when the gas flow path is a straight flow path, the current extraction portion of the terminal passes through the center in the cell plane and intersects with the two lines at right angles to each other. It can be provided in a region where a gas supply port is provided in a region obtained by dividing the plane into four.

  Since the fuel cell according to the present invention has a configuration in which the gas supply port and the current extraction portion of the terminal are provided close to each other, the potential in the cell plane can be made uniform, and excellent power generation efficiency can be obtained. Can keep.

  Next, a fuel cell according to a preferred embodiment of the present invention will be described with reference to the drawings. In addition, embodiment described below is the illustration for demonstrating this invention, and this invention is not limited only to these embodiment. Therefore, the present invention can be implemented in various forms without departing from the gist thereof.

  1 is a side view schematically showing the fuel cell according to the present embodiment, FIG. 2 is a plan view of the fuel cell separator shown in FIG. 1 as viewed from the hydrogen gas flow path side, and FIG. 3 is shown in FIG. It is the top view seen from the oxygen gas channel side of the separator of the shown fuel cell.

  As shown in FIGS. 1 to 3, a cell 11 that is a constituent element of the fuel cell 1 according to the present embodiment includes, for example, an electrolyte membrane made of an ion exchange membrane, and a catalyst layer disposed on one surface of the electrolyte membrane. And a membrane-electrode assembly (MEA) comprising an electrode (anode, fuel electrode) comprising a diffusion layer and a catalyst layer (cathode, air electrode) comprising a catalyst layer and a diffusion layer disposed on the other surface of the electrolyte membrane. And a separator 30 that forms a gas flow path for supplying a fuel gas (hydrogen) and an oxidizing gas (oxygen, usually air) to the pair of electrodes.

  A hydrogen gas passage 31 including a serpentine passage for supplying hydrogen to the fuel electrode is formed on the surface of the separator 30 facing the fuel electrode. The hydrogen gas flow path 31 has one end connected to the hydrogen inlet 32 and the other end connected to the hydrogen outlet 34. In the vicinity of the hydrogen inlet 32, as shown in FIGS. 2 and 3 in particular, a current extraction portion 42A of a terminal 12A described later is provided.

  On the other hand, an oxygen gas flow path 35 including a serpentine flow path for supplying oxygen to the air electrode is formed on the surface of the separator 30 facing the air electrode. The oxygen gas flow path 35 has one end connected to the oxygen inlet 36 and the other end connected to the oxygen outlet 37. Near the oxygen inlet 36, as shown in FIGS. 2 and 3, in particular, a current extraction portion 42B of a terminal 12B described later is provided.

  Reference numeral 38 denotes a cooling water inlet, and reference numeral 39 denotes a cooling water outlet.

  The cell 11 having this configuration forms a cell stack 10 by stacking a plurality of (for example, 200 cells). A terminal 12A, an insulator 13A, and an end plate 14A are arranged in this order on one end side (left side in FIG. 1) of the cell stack 10 in the cell stacking direction. Further, a terminal 12B, an insulator 13B, and an end plate 14B are disposed in this order on the other end side (the right side in FIG. 1) of the cell stack 10 in the cell stacking direction.

  The terminal 12 </ b> A is provided with a current extraction portion 42 </ b> A, and this current extraction portion 42 </ b> A is located in the vicinity of the hydrogen inlet 32. The terminal 12B is provided with a current extraction part 42B, and this current extraction part 42B is located in the vicinity of the oxygen inlet 36.

  Then, the stack 20 is constituted by these parts, and the stack 20 is fixed with a fastening member 24 (for example, a tension plate, a through bolt, etc.) and a bolt 25 or a nut, and is fastened in the cell stacking direction, thereby fuel cell 1. Is configured.

  In the fuel cell 1 having this configuration, the current extraction portion 42A of the terminal 12A has a large current density and a low potential during power generation in the vicinity of the hydrogen inlet 32 having a large gas partial pressure in the cell plane and high power generation efficiency. In addition, since the current extraction portion 42B of the terminal 12B where the current density is large and the potential during power generation is low is provided in the vicinity of the oxygen inlet 36 where the power generation efficiency is high, the potential in the cell plane can be made uniform. it can. As a result, local degradation in the cell plane can be prevented, and the power generation can be performed with a long lifetime and high efficiency.

  In the present embodiment, the case where the current extraction portion 42A is provided in the vicinity of the hydrogen inlet 32 and the current extraction portion 42B is provided in the vicinity of the oxygen inlet 36 has been described. However, the present invention is not limited to this. The current extraction part 42B may be provided in the vicinity of the hydrogen inlet 32 without providing the current extraction part 42B in the vicinity of 36, or the current extraction part 42A may not be provided in the vicinity of the hydrogen inlet 32. A configuration in which a current extraction portion 42B is provided in the vicinity of the oxygen inlet 36 may be employed.

  In the present embodiment, the case where the hydrogen inlet 32, the oxygen inlet 36, and the current extraction parts 42A and 42B are disposed at the positions shown in FIGS. 2 and 3 is described. As shown in FIG. 4, 42 </ b> A is preferably disposed in a region up to the vicinity of the first turn portion 31 </ b> U of the hydrogen gas flow path 31 (a region indicated by a one-dot chain line in FIG. 4). FIG. 4 is a plan view seen from the hydrogen gas flow path side of the separator of the fuel cell according to another embodiment.

  Further, as shown in FIG. 5, the current extraction portion 42 </ b> B is preferably arranged in a region (region indicated by a one-dot chain line in FIG. 5) up to the vicinity of the first turn portion 35 </ b> U of the oxygen gas flow path 35. FIG. 5 is a plan view seen from the oxygen gas flow path side of the separator of the fuel cell according to another embodiment.

  In the present embodiment, the case where the hydrogen gas flow path 31 and the oxygen gas flow path 35 are serpentine flow paths has been described, but not limited thereto, the hydrogen gas flow path 31 and the oxygen gas flow path 35 The shape can take a desired shape, such as a straight channel.

For example, as shown in FIG. 6, when the hydrogen gas flow path 31 is a straight flow path, the current extraction portion 42A passes through the center O in the cell plane and intersects the two lines L ₁ that intersect at right angles with each other. Of the regions divided into four in the cell plane by L ₂ , it is preferable to be disposed in the region where the hydrogen inlet 32 is disposed (the region indicated by the dotted line in FIG. 6). FIG. 6 is a plan view seen from the hydrogen gas flow path side of the separator of the fuel cell according to another embodiment.

Also, for example, as shown in FIG. 7, when the oxygen gas flow path 35 is a straight flow path, the current extraction portion 42B passes through the center O in the cell plane and intersects the two lines L ₁ that intersect at right angles with each other. Of the regions divided into four in the cell plane by L ₂ , the region is preferably disposed in the region where the oxygen inlet 36 is disposed (the region indicated by the dotted line in FIG. 7). FIG. 7 is a plan view seen from the oxygen gas flow path side of the separator of the fuel cell according to another embodiment.

  In addition, when the hydrogen gas flow path 31 and the oxygen gas flow path 35 are straight flow paths, if desired, the current extraction section 42B is not provided in the vicinity of the oxygen inlet 36 but the current extraction section in the vicinity of the hydrogen inlet 32. 42A may be provided, or a current extraction part 42B may be provided in the vicinity of the oxygen inlet 36 without providing the current extraction part 42A in the vicinity of the hydrogen inlet 32.

  Further, it is possible to eliminate the bias of the current density distribution by taking out the current from the entire area of the terminals 12A and 12B.

  The cell stack is provided with a plurality of gas supply ports, and further has a plurality of power extraction terminal terminals provided in the cell stack, and a current extraction portion of the terminal in the vicinity of at least one of the gas supply ports. May be provided. Preferably, in the two terminal terminals existing at both ends of the cell stack (stack), each terminal is preferably provided in at least one of the vicinity of the fuel gas supply port and the vicinity of the oxidizing gas supply port.

It is a side view which shows typically the fuel cell concerning this Embodiment. It is the top view seen from the hydrogen gas flow path side of the separator of the fuel cell shown in FIG. It is the top view seen from the oxygen gas flow path side of the separator of the fuel cell shown in FIG. It is the top view seen from the hydrogen gas channel side of the separator of the fuel cell concerning other embodiments of the present invention. It is the top view seen from the oxygen gas channel side of the separator of the fuel cell concerning other embodiments of the present invention. It is the top view seen from the hydrogen gas channel side of the separator of the fuel cell concerning other embodiments of the present invention. It is the top view seen from the oxygen gas channel side of the separator of the fuel cell concerning other embodiments of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell 30 Separator 31 Hydrogen gas flow path 32 Hydrogen inlet 35 Oxygen gas flow path 36 Oxygen inlet 42A, 42B Current extraction part

Claims (5)

A cell stack in which a plurality of single cells are stacked;
A gas supply port provided in communication with the cell stack and supplying a reaction gas to the gas flow path of each single cell;
A terminal provided in the cell stack;
With
A fuel cell in which a current extraction portion of a terminal corresponding to the gas supply port is provided in the vicinity of the gas supply port.   The fuel cell according to claim 1, wherein the gas supply port is provided at a portion where the current density is increased during power generation.   The fuel cell according to claim 1, wherein the current extraction portion of the terminal is provided at a portion where a gas partial pressure of the reaction gas is high.   The said gas flow path is a serpentine flow path, The electric current extraction part of the said terminal is provided in the area | region to the 1st turn part vicinity of the said gas flow path. A fuel cell according to claim 1. The gas flow path is a straight flow path, and the current extraction portion of the terminal is the gas in a region divided into four in the cell plane by two lines passing through the center in the cell plane and intersecting at right angles to each other. The fuel cell according to any one of claims 1 to 3, wherein the fuel cell is provided in a region where a supply port is provided.

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