KR20170127250A - Electrolyte membrane and fuel cell comprising the same - Google Patents

Abstract

The present invention relates to an electrolyte membrane and a fuel cell composing the same. One embodiment of the present invention provides an electrolyte membrane comprising: a hydrocarbon-based polymer; and a reactive inorganic material including an epoxy group. One embodiment of the present invention provides a membrane-electrode assembly comprising: an anode; a cathode; and the electrolyte membrane interposed between the anode and the cathode. One embodiment of the present invention provides an electrolyte-type fuel cell comprising: a stack including two or more membrane-electrode assemblies and a bipolar plate interposed therebetween; a fuel supply unit supplying fuel to the stack; and an oxidizing agent supply unit supplying an oxidizing agent to the stack. The electrolyte membrane of one embodiment of the present invention has excellent cell performance and mechanical properties under low-humidity conditions.

Description

ELECTROLYTE MEMBRANE AND FUEL CELL COMPRISING THE SAME BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

TECHNICAL FIELD The present invention relates to an electrolyte membrane and a fuel cell including the electrolyte membrane.

In a fuel cell including a polymer electrolyte membrane, the fluorine-based polymer electrolyte membrane is widely known for its high performance and durability. In particular, the durability of the fluorinated polymer electrolyte membranes is evaluated stably by the RH cycle test. On the other hand, the hydrocarbon polymer electrolyte membranes are more cost competitive than the fluorinated polymer electrolyte membranes Much research is underway. A variety of additives are used to overcome the disadvantages of the hydrocarbon electrolyte membrane in which the ionic conductivity and the performance are largely reduced in the low humidification, and the mechanical properties of the membrane are lowered when the inorganic additives are used. Therefore, it is necessary to study the additives that can improve the cell performance without deteriorating the mechanical properties.

Korean Patent Publication No. 2009-0039180

The present specification intends to provide an electrolyte membrane and fuel electricity including the electrolyte membrane.

According to one embodiment of the present invention, a hydrocarbon-based polymer; And a reactive inorganic material containing an epoxy group.

One embodiment of the present disclosure relates to an anode; Cathode; And an electrolyte membrane provided between the anode and the cathode.

One embodiment of the present disclosure relates to a stack comprising at least two membrane-electrode assemblies according to the above and a bipolar plate provided between the membrane-electrode assemblies; A fuel supply unit for supplying fuel to the stack; And an oxidant supplier for supplying an oxidant to the stack.

The electrolyte membrane according to one embodiment of the present invention has excellent cell performance and mechanical properties under low humidity conditions.

1 is a schematic view showing an electricity generation principle of a fuel cell.
2 is a schematic view showing an embodiment of a fuel cell.

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

Whenever a component is referred to as "comprising ", it is to be understood that the component may include other components as well, without departing from the scope of the present invention.

As used herein, the term "electrolyte membrane" is a membrane capable of ion exchange, and includes a membrane, an ion exchange membrane, an ion transport membrane, an ion conductive membrane, a membrane, an ion exchange membrane, A transfer electrolyte membrane, an ion conductive electrolyte membrane, and the like.

According to one embodiment of the present invention, a hydrocarbon-based polymer; And a polymer electrolyte membrane comprising a reactive inorganic material, wherein the reactive inorganic material comprises an epoxy group.

According to one embodiment of the present invention, the size of the reactive inorganic material is 0.01 nm or more and 10 nm or less, more specifically, 0.01 nm or more and 5 nm or less. When the size of the inorganic material is 10 nm or more, it is difficult to disperse the inorganic material without using a dispersant.

The size of the inorganic material in this specification means the particle size, and the length corresponding to the diameter of the spherical shape can be measured using an electron microscope.

According to an embodiment of the present invention, the electrolyte membrane includes 0.1 to 10 parts by weight of the reactive inorganic material based on 100 parts by weight of the hydrocarbon-based polymer. When the content is lower than 0.1 part by weight, the effect is insignificant because the amount thereof is small, and when the content is higher than 10 parts by weight, the dispersibility during solution and film production is poor.

According to one embodiment of the present invention, the reactive inorganic material is a silica-based inorganic material.

According to one embodiment of the present invention, silsesquioxane containing an epoxy group may be used as the reactive inorganic material.

As the epoxy-containing reactive inorganic material, EP0408, EP0409, EP0421, EP0423 of Hybrid plastics or SQ-506 of Arakawa Chemical may be used, but the present invention is not limited thereto.

According to one embodiment of the present invention, the hydrocarbon-based polymer comprises a sulfonic acid group.

According to one embodiment of the present invention, in the case of the electrolyte membrane containing the reactive inorganic material and the sulfonic acid group, the electrolyte membrane reacts with the sulfonic acid group in the reactive inorganic material and the electrolyte membrane to form a cured structure. Therefore, the hydrocarbon polymer exhibits improved mechanical properties compared to the conventional electrolyte membrane. Further, since the hydrocarbon polymer includes a side chain group, the compatibility with the polymer increases, and even when the dispersant is not present, the dispersibility of silica as an inorganic material is improved.

According to one embodiment of the present invention, the hydrocarbon-based polymer is at least one selected from the group consisting of sulfonimide benzimidazole-based polymers, sulfonated polyimide-based polymers, sulfonated polyetherimide-based polymers, sulfonated polyphenylene sulfide- A sulfonated polyether sulfone type polymer, a sulfonated polyether ketone type polymer, a sulfonated polyether-ether ketone type polymer, and a sulfonated polyphenylquinoxaline type polymer, but the present invention is not limited thereto.

According to one embodiment of the present invention, the weight average molecular weight of the hydrocarbon-based polymer is 100,000 to 2,000,000, and the weight average molecular weight of the polymer is more preferably 300,000 to 2,000,000. In the case of forming an electrolyte membrane with a polymer having a weight average molecular weight of 300,000 or less, the mechanical properties of the electrolyte membrane are deteriorated and it is difficult to form the electrode-membrane junction body. When a polymer having a molecular weight of 2,000,000 or more is used, the viscosity of the polymer is increased, .

According to one embodiment of the present invention, the ionic conductivity of the electrolyte membrane is 0.001 mS / cm to 400 mS / cm.

In one embodiment of the present invention, the ionic conductivity of the polymer electrolyte membrane can be measured under a humidifying condition. In this specification, the humidifying condition may be selected from 10% to 100% relative humidity (RH).

An electrolyte membrane according to one embodiment of the present disclosure may be manufactured using materials and / or methods known in the art, except that the electrolyte membrane includes the hydrophilic block.

The electrolyte membrane according to one embodiment of the present invention may be prepared by polymerizing a block copolymer containing the hydrophilic block, blending the block copolymer to prepare a polymer solution composition, and then casting the blended polymer solution composition to prepare an electrolyte membrane .

According to one embodiment of the present invention, the thickness of the electrolyte membrane may be 1 탆 to 100 탆, specifically 5 탆 to 50 탆. When the thickness of the electrolyte membrane is 1 占 퐉 to 100 占 퐉, the electric short and the cross over of the electrolyte material can be lowered, and excellent cation conductivity characteristics can be exhibited.

The disclosure also includes an anode; Cathode; And the above-described polymer electrolyte membrane provided between the anode and the cathode.

The membrane-electrode assembly (MEA) means a junction body of an electrode (cathode and anode) where an electrochemical catalytic reaction of fuel and air takes place and a polymer membrane in which hydrogen ions are transferred, and the electrode (cathode and anode) It is a single integral unit.

The membrane-electrode assembly of the present invention can be produced by a conventional method known in the art, such that the catalyst layer of the anode and the catalyst layer of the cathode are in contact with the electrolyte membrane. For example, the cathode; Anode; And an electrolyte membrane positioned between the cathode and the anode in close contact with each other at 100 ° C to 400 ° C.

The anode electrode may include an anode catalyst layer and an anode gas diffusion layer. The anode gas diffusion layer may again include an anode microporous layer and an anode electrode substrate.

The cathode electrode may include a cathode catalyst layer and a cathode gas diffusion layer. The cathode gas diffusion layer may again include a cathode microporous layer and a cathode electrode substrate.

FIG. 1 schematically shows an electricity generating principle of a fuel cell. In a fuel cell, a basic unit for generating electricity is a membrane electrode assembly (MEA), which includes an electrolyte membrane 100 and an electrolyte membrane 100, And an anode 200a and a cathode 200b electrodes formed on both sides of the cathode 200a. 1 showing the principle of electricity generation of a fuel cell, in the anode 200a, oxidation reaction of hydrogen such as hydrogen or hydrocarbons such as methanol and butane occurs, hydrogen ions (H +) and electrons (e-) are generated, The hydrogen ions move through the electrolyte membrane 100 to the cathode 200b. In the cathode 200b, hydrogen ions transferred through the electrolyte membrane 100 react with an oxidizing agent such as oxygen and electrons to generate water. This reaction causes electrons to migrate to the external circuit.

The catalyst layer of the anode electrode is preferably a catalyst selected from the group consisting of platinum, ruthenium, osmium, platinum-ruthenium alloy, platinum-osmium alloy, platinum-palladium alloy and platinum- Lt; / RTI > The catalyst layer of the cathode electrode is a place where a reduction reaction of an oxidizing agent occurs, and a platinum or platinum-transition metal alloy can be preferably used as a catalyst. The catalysts can be used not only by themselves but also by being supported on a carbon-based carrier.

The process of introducing the catalyst layer can be performed by a conventional method known in the art. For example, the catalyst ink may be directly coated on the electrolyte membrane, or a catalyst layer may be formed on the releasable substrate, followed by thermocompression bonding to the electrolyte membrane, The catalyst layer may be formed by removing the substrate or by coating the gas diffusion layer. Here, the method of coating the catalyst ink is not particularly limited, but spray coating, tape casting, screen printing, blade coating, die coating, spin coating or inkjet coating may be used. The catalyst ink may typically consist of a catalyst, a polymer ionomer and a solvent.

The gas diffusion layer serves as a current conductor and serves as a passage for reacting gas and water, and has a porous structure. Therefore, the gas diffusion layer may include a conductive base material. As the conductive substrate, carbon paper, carbon cloth or carbon felt can be preferably used. The gas diffusion layer may further include a microporous layer between the catalyst layer and the conductive base. The microporous layer can be used to improve the performance of the fuel cell under low humidification conditions and serves to reduce the amount of water flowing out of the gas diffusion layer to make the electrolyte membrane sufficiently wet.

One embodiment of the present disclosure includes at least two membrane-electrode assemblies; A stack including a bipolar plate disposed between the membrane-electrode assemblies; A fuel supply unit for supplying fuel to the stack; And an oxidant supply unit for supplying an oxidant to the stack.

Fuel cells are energy conversion devices that convert the chemical energy of a fuel directly into electrical energy. That is, a fuel cell uses a fuel gas and an oxidizing agent, and generates electricity using electrons generated during the oxidation-reduction reaction.

The fuel cell can be manufactured according to a conventional method known in the art using the above-described membrane-electrode assembly (MEA). For example, the membrane electrode assembly (MEA) and the bipolar plate may be fabricated.

The fuel cell of the present invention comprises a stack, a fuel supply, and an oxidant supply.

2 schematically illustrates the structure of a fuel cell, which includes a stack 60, an oxidant supply unit 70, and a fuel supply unit 80. As shown in FIG.

The stack 60 includes one or more of the membrane electrode assemblies described above and includes a separator interposed therebetween when two or more membrane electrode assemblies are included. The separator serves to prevent the membrane electrode assemblies from being electrically connected and to transfer the fuel and oxidant supplied from the outside to the membrane electrode assembly.

The oxidant supply part 70 serves to supply the oxidant to the stack 60. As the oxidizing agent, oxygen is typically used, and oxygen or air can be injected into the pump 70 and used.

The fuel supply unit 80 serves to supply the fuel to the stack 60 and includes a fuel tank 81 for storing the fuel and a pump 82 for supplying the fuel stored in the fuel tank 81 to the stack 60 Lt; / RTI > As the fuel, gas or liquid hydrogen or hydrocarbon fuel may be used. Examples of hydrocarbon fuels include methanol, ethanol, propanol, butanol or natural gas.

The fuel cell may be a polymer electrolyte fuel cell, a direct liquid fuel cell, a direct methanol fuel cell, a direct formic acid fuel cell, a direct ethanol fuel cell, or a direct dimethyl ether fuel cell.

According to one embodiment of the present disclosure, there is provided a fuel cell including the above-described electrolyte membrane.

Hereinafter, examples and comparative examples are provided to facilitate understanding of the contents of the present specification. However, the content of the present specification is not limited to the following examples.

<Reference example>

1) Synthesis of polymer

A solution prepared by adding 8.3 g of bisphenol A, 28.7 g of 4,4-difluorobenzophenone, 22.7 g of hydroquinone sulfonic acid-potassium salt, 37 g of potassium carbonate salt, 220 g of dimethyl sulfoxide (DMSO) and 200 g of benzene was added to a round bottom flask After azotropy was performed at 140 ° C, benzene was removed and the temperature was raised to 180 ° C to carry out the polymerization. The solution with increased viscosity was immersed in water and further washed with water to remove residual potassium carbonate salt and dried in an oven at 80 ° C for more than one day. (Weight average molecular weight, 300 KDa)

2) Preparation of blending polymer solution composition

The hydrocarbon-based polymer synthesized by the above-described method was dissolved in dimethylsulfoxide (DMSO) solvent in a ratio of 95: 5 and filtered to prepare a polymer solution composition.

3) Film casting

The blended polymer solution composition was used to cast a polymer film on a substrate using a doctor blade on a horizontal plate of an applicator in a clean bench and then kept at 50 ° C for 2 hours or longer. And dried for one day to prepare a blended hydrocarbon-based polymer electrolyte membrane.

&Lt; Example 1 >

In the preparation of the blended polymer solution composition of the Reference Example, a polymer electrolyte membrane was prepared using a blending polymer solution containing 3 parts by weight of SQ-506 (Arakawa) based on 100 parts by weight of a hydrocarbon polymer.

&Lt; Example 2 >

An electrolyte membrane was prepared in the same manner as in Experimental Example 1, except that 5 parts by weight of SQ-506 (Arakawa) was used instead of 3 parts by weight of the above Example 1.

&Lt; Comparative Example 1 &

An electrolyte membrane was prepared in the same manner as in Experimental Example 1, except that the reactive inorganic material was not used in Example 1.

&Lt; Comparative Example 2 &

An electrolyte membrane was prepared in the same manner as in Experimental Example 1, except that 5 parts by weight of silica (aerosil 380) containing no reactive group was used instead of 3 parts by weight of the reactive inorganic material in Example 1.

Table 1 shows the results of evaluating cell performance of each electrolyte membrane in Experimental Examples 1 and 2 and Comparative Examples 1 and 2.

MEA FS_Current Density Forward (mA / cm ² @ 0.6V) / OCV 100% RH 50% RH Example 1 1257 / 0.906 1311 / 0.905 Example 2 1148 / 0.926 1295 / 0.930 Comparative Example 1 1105 / 0.966 1064 / 0.991 Comparative Example 2 884 / 0.899 954 / 0.890

As can be seen from Table 1, the performance of the electrolyte membrane prepared in Experimental Examples 1 and 2 was improved at low humidification, and the more the amount of inorganic material added, the more effective it is.

The results of evaluating the mechanical properties of the electrolyte membranes of Experimental Examples 1 and 2 and Comparative Examples 1 and 2 are shown in Table 2 below.

22 ° C 40% RH Young's modulus (kgf / cm) Breaking point stress (kgf / cm ² ) Example 1 5.74 689 Example 2 5.58 723 Comparative Example 1 6.17 590 Comparative Example 2 6.46 425

In the case of the electrolyte membrane including the above-prepared inorganic particles, the polymer electrolyte membrane is chemically bonded to the polymer electrolyte, thereby exhibiting excellent mechanical properties as compared with a membrane containing inorganic particles having no reactivity.

100: electrolyte membrane
200a: anode
200b: cathode
60: Stack
70: oxidant supplier
80: fuel supply unit
81: Fuel tank
82: Pump

Claims (13)

Hydrocarbon-based polymers; And an electrolyte containing a reactive inorganic material containing an epoxy group. The electrolyte membrane according to claim 1, wherein the reactive inorganic material has a size of 0.01 nm or more and 10 nm or less. The electrolyte membrane according to claim 1, wherein the reactive inorganic material has a size of 0.01 nm or more and 5 nm or less. The electrolyte membrane according to claim 1, wherein the electrolyte membrane comprises 0.1 to 10 parts by weight of the reactive inorganic material based on 100 parts by weight of the hydrocarbon-based polymer. The electrolyte membrane according to claim 1, wherein the reactive inorganic material is a silica-based inorganic material. The electrolyte membrane according to claim 1, wherein the reactive inorganic material is silsesquioxane containing an epoxy group. The electrolyte membrane according to claim 1, wherein the hydrocarbon-based polymer comprises a sulfonic acid group. [4] The method of claim 1, wherein the hydrocarbon-based polymer is selected from the group consisting of a sulfonated benzimidazole-based polymer, a sulfonated polyimide-based polymer, a sulfonated polyetherimide-based polymer, a sulfonated polyphenylene sulfide- A sulfonated polyether ketone-based polymer, a sulfonated polyether-ether ketone-based polymer, and a sulfonated polyphenylquinoxaline-based polymer. The electrolyte membrane according to claim 1, wherein the hydrocarbon-based polymer has a weight average molecular weight of 100,000 to 2,000,000. The electrolyte membrane according to claim 1, wherein the electrolyte membrane has an ion conductivity of 0.001 mS / cm to 400 mS / cm. The electrolyte membrane according to claim 1, wherein the electrolyte membrane has a thickness of 1 탆 to 100 탆. anode; cathode; And an electrolyte membrane provided between the anode and the cathode,
Wherein the electrolyte membrane is an electrolyte membrane according to any one of claims 1 to 11. A stack including at least two membrane-electrode assemblies according to claim 12 and a bipolar plate provided between the membrane-electrode assemblies;
A fuel supply unit for supplying fuel to the stack; And
And an oxidant supplier for supplying an oxidant to the stack.

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