KR20050119366A - A membrane for fuel cell and a fuel cell comprising the same - Google Patents

Abstract

The present invention relates to a polymer membrane / electrode assembly for a fuel cell and a fuel cell including the same, wherein the polymer membrane / electrode assembly includes: an anode and a cathode electrode disposed to face each other; And a polymer electrolyte membrane positioned between the anode and the cathode electrode, wherein the polymer electrolyte membrane includes a hydrogen ion conductive polymer and an organic compound capable of collecting metal impurities. The fuel cell includes at least one membrane / electrode assembly including an anode and a cathode electrode disposed to face each other, and a polymer electrolyte membrane positioned between the anode and the cathode electrode; And a bipolar plate having a flow channel formed in contact with one of an anode and a cathode of the membrane / electrode assembly to supply gas, wherein the polymer electrolyte membrane is an organic compound capable of collecting hydrogen ion conductive polymer and metal impurities It includes.

Description

Polymer membrane / electrode assembly for fuel cell and fuel cell comprising same {A MEMBRANE FOR FUEL CELL AND A FUEL CELL COMPRISING THE SAME}

[Industrial use]

The present invention relates to a fuel cell polymer membrane / electrode assembly and a fuel cell including the same, and more particularly, to a fuel cell including an organic compound capable of collecting metal impurities, thereby improving the electrochemical reaction efficiency of the fuel cell. A polymer membrane / electrode assembly and a fuel cell comprising the same.

[Prior art]

A fuel cell is a power generation system that directly converts the chemical reaction energy of hydrogen and oxygen contained in hydrocarbon-based materials such as methanol, ethanol and natural gas into electrical energy.

Fuel cells are classified into phosphoric acid fuel cells, molten carbonate fuel cells, solid oxide fuel cells, polymer electrolyte or alkaline fuel cells, etc., depending on the type of electrolyte used. Each of these fuel cells operates on essentially the same principle, but differs in the type of fuel used, operating temperature, catalyst, electrolyte, and the like.

Among these, the polymer electrolyte fuel cell (PEMFC), which is being developed recently, has superior output characteristics compared to other fuel cells, has a low operating temperature, fast start-up and response characteristics, and a mobile power source such as an automobile. Of course, it has a wide range of applications, such as distributed power supply for homes, public buildings and small power supply for electronic devices.

Such a PEMFC basically includes a stack, a reformer, a fuel tank, a fuel pump, and the like to constitute a system. The stack forms the body of the fuel cell, and the fuel pump supplies the fuel in the fuel tank to the reformer. The reformer reforms the fuel to generate hydrogen gas and supplies the hydrogen gas to the stack. Thus, the PEMFC supplies fuel in the fuel tank to the reformer by operation of the fuel pump, reforming the fuel in the reformer to generate hydrogen gas, and electrochemically reacting the hydrogen gas and oxygen in the stack to generate electrical energy. Let's do it.

In such a fuel cell system, a stack that substantially generates electricity is stacked with several to several tens of unit cells including a membrane electrode assembly (MEA) and a bipolar plate that adheres to both sides thereof. Has a structure. The membrane / electrode assembly has a structure in which an anode electrode and a cathode electrode are coupled with an electrolyte membrane interposed therebetween. The bipolar plate separates the respective membrane / electrode assemblies and serves as a passage for supplying hydrogen gas and oxygen required for the reaction of the fuel cell to the anode electrode and the cathode electrode of the membrane / electrode assembly, and for each membrane / electrode assembly. It simultaneously serves as a conductor that connects the anode and cathode electrodes in series. Hydrogen gas is supplied to the anode electrode through the bipolar plate, while oxygen is supplied to the cathode electrode. In this process, an oxidation reaction of hydrogen gas occurs at an anode electrode, and a reduction reaction of oxygen occurs at a cathode electrode, thereby generating electricity due to the movement of electrons generated, and additionally generating heat and moisture.

In the power generation system of a polymer fuel cell, the performance of a polymer membrane / electrode assembly (MEA) has a great influence on the power generation characteristics.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fuel cell polymer membrane / electrode assembly capable of capturing metal impurities melted from various members of a fuel cell during operation of the fuel cell to improve the electrochemical reaction efficiency of the fuel cell, and a fuel cell including the same. It is to.

In order to achieve the above object, the present invention provides an anode and a cathode electrode located opposite each other; And a polymer electrolyte membrane positioned between the anode and the cathode electrode, wherein the polymer electrolyte membrane provides a polymer membrane / electrode assembly for a fuel cell including a hydrogen ion conductive polymer and an organic compound capable of collecting metal impurities.

The invention also includes at least one membrane / electrode assembly comprising an anode and a cathode electrode positioned opposite each other, and a polymer electrolyte membrane positioned between the anode and the cathode electrode; And a bipolar plate having a flow channel formed in contact with one of an anode and a cathode of the membrane / electrode assembly to supply gas, wherein the polymer electrolyte membrane is an organic compound capable of collecting hydrogen ion conductive polymer and metal impurities It provides a fuel cell comprising a.

Hereinafter, the present invention will be described in more detail.

In the fuel cell system, the reformer and bipolar plate are generally made of metal, so that metal impurities may occur while the reaction gas passes through them. If the fuel cell is operated for a long time at high temperature, various metal components used for the electrode catalyst may melt. To form impurities. The polymer membrane of the fuel cell should be impermeable to gases used as fuel in addition to hydrogen ions, and should not allow metal impurities that may melt during prolonged operation of the fuel cell.

In order to solve this problem, the present invention includes an organic compound capable of collecting metal impurities in the polymer electrolyte membrane to efficiently remove metal impurities. The polymer used in the polymer electrolyte membrane is not particularly limited as long as it has hydrogen ion conductivity, and preferably, a fluorine polymer, a ketone polymer, a benzimidazole polymer, an ester polymer, an amide polymer, an imide polymer, and a sulfone polymer , Styrene-based polymers, and the like, and specific examples thereof include tetrafluoroethylene and fluorovinyl ether copolymers including poly (perfluorosulfonic acid), poly (perfluorocarboxylic acid), and sulfonic acid groups. Defluorinated polyetherketones, aryl ketones, poly (2,2 '-(m-phenylene) -5,5'-bibenzimidazole) (poly (2,2'-(m-phenylene)- 5,5'-bibenzimidazole)), poly (2,5-benzimidazole), polyimide, polysulfone, polystyrene, polyphenylene and the like can be used, but is not limited thereto.

As the organic compound capable of collecting the metal, a crown ether compound may be preferably used. Specific examples of the crown ether compound include 12-crown-4-ether, 15-crown-5-ether, 18-crown-6-ether, benzo-15-crown-5-ether, N-phenylazo-15-crown -5-ether and the like. The organic compound is preferably used in 1 to 10 parts by weight based on 100 parts by weight of the polymer.

The organic compound may be added during polymer polymerization to be dispersed and present in a polymer matrix. The organic compound may be mixed and molded to prepare a polymer membrane, or an organic compound may be added to an electrolyte present in the polymer membrane. .

The polymer electrolyte membrane is positioned between the cathode and the anode to form a membrane / electrode assembly. The operating state of a fuel cell comprising such an anode 3, a cathode 5, and a polymer membrane 7 is schematically illustrated in FIG. 1. Hydrogen or fuel is supplied to the anode and oxygen is supplied to the cathode to generate electricity by electrochemical reaction of the anode and the cathode. An oxidation reaction of hydrogen or organic fuel occurs at the anode and a reduction reaction of oxygen occurs at the cathode to generate a voltage difference between the two electrodes.

The fuel cell inserts a membrane / electrode assembly between a gas flow channel and a bipolar plate on which a cooling channel is formed to fabricate a unit cell, stacks it, and manufactures a stack, and then inserts it between two end plates. Can be prepared. Fuel cells can be readily manufactured by conventional techniques in the art.

Hereinafter, preferred examples and comparative examples of the present invention are described. However, the following examples are only one preferred embodiment of the present invention and the present invention is not limited to the following examples.

(Example 1)

A polymer was prepared by adding 2 parts by weight of 12-crown-4-ether to 100 parts by weight of Nafion (Dupont Chemical) polymer and then molding into a polymer membrane. The polymer membrane was placed between an anode and a cathode and calcined at 100 ° C. for 1 minute, followed by hot rolling to prepare a membrane / electrode assembly. The anode and the cathode were prepared by coating a catalyst slurry prepared by mixing isopropyl alcohol with platinum-supported carbon powder (Pt / C), a polytetrafluoroethylene binder polymer, and a solvent.

The prepared membrane / electrode assembly is inserted between two gaskets, and then inserted into two bipolar plates in which a gas channel channel and a cooling channel of a predetermined shape are formed, and then compressed into a copper end plate. The battery was prepared.

(Comparative Example 1)

A unit cell was prepared in the same manner as in Example 1, except that 12-crown-4-ether was not added.

In the unit cell prepared according to Example 1, it was confirmed that the crown ether compound collects metal impurities, thereby improving the electrochemical reaction efficiency of the battery as compared to Comparative Example 1.

The polymer membrane / electrode assembly of the present invention may include an organic compound capable of collecting metal impurities in the polymer electrolyte membrane to remove metal impurities that may occur during operation of the fuel cell, thereby maintaining excellent battery efficiency.

1 is a schematic view showing an operating state of a fuel cell including a polymer membrane.

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

1: fuel cell 3: anode

5: cathode 7: polymer membrane

Claims (10)

Anode and cathode electrodes positioned opposite one another; And A polymer electrolyte membrane positioned between the anode and the cathode electrode, The polymer electrolyte membrane is a fuel cell polymer membrane / electrode assembly comprising a hydrogen ion conductive polymer and an organic compound capable of collecting metal impurities. The method of claim 1, wherein the hydrogen ion polymer is selected from the group consisting of fluorine-based polymers, ketone-based polymers, benzimidazole-based polymers, ester-based polymers, amide-based polymers, imide-based polymers, sulfone-based polymers, and styrene-based polymers At least one polymer membrane / electrode assembly for a fuel cell. The polymer membrane / electrode assembly of claim 1, wherein the organic compound is a crown ether. The compound according to claim 3, wherein the organic compound is 12-crown-4-ether, 15-crown-5-ether, 18-crown-6-ether, and benzo-15-crown-5-ether, and N-phenylazo A polymer membrane / electrode assembly for fuel cells, wherein the polymer cell is at least one selected from the group consisting of -15-crown-5-ether. The polymer membrane / electrode assembly of claim 1, wherein the organic compound is present in an amount of 1 to 10 parts by weight based on 100 parts by weight of the polymer. At least one membrane / electrode assembly comprising an anode and a cathode electrode positioned opposite each other, and a polymer electrolyte membrane positioned between the anode and the cathode electrode; And A bipolar plate having a flow channel for supplying a gas in contact with one of an anode and a cathode of the membrane / electrode assembly; The polymer electrolyte membrane is a fuel cell comprising a hydrogen ion conductive polymer and an organic compound capable of collecting metal impurities. The method of claim 6, wherein the polymer is at least one selected from the group consisting of fluorine-based polymers, ketone-based polymers, benzimidazole-based polymers, ester-based polymers, amide-based polymers, imide-based polymers, sulfone-based polymers, and styrene-based polymers. Fuel cell. The fuel cell of claim 6, wherein the organic compound is a crown ether. The compound according to claim 8, wherein the organic compound is 12-crown-4-ether, 15-crown-5-ether, 18-crown-6-ether, and benzo-15-crown-5-ether, and N-phenylazo At least one fuel cell selected from the group consisting of -15-crown-5-ether. The fuel cell of claim 6, wherein the organic compound is present in an amount of 1 to 10 parts by weight based on 100 parts by weight of the polymer.