KR101034706B1 - Electrolyte for solid oxide fuel cell and manufacturing method of the same - Google Patents

Abstract

Disclosed are an electrolyte composite of a solid oxide fuel cell having reduced electrical resistance and improved ion conductivity, and a method of manufacturing the same. The method for manufacturing an electrolyte composite of a solid oxide fuel cell includes preparing a porous support having a plurality of pores and depositing vanadium oxide on the support.

Solid oxide fuel cell (SOFC), electrolyte composite, ion conductivity

Description

ELECTROLYTE COMPOSITE OF SOLID OXIDE FUEL CELL AND MANUFACTURING METHOD THEREOF {ELECTROLYTE FOR SOLID OXIDE FUEL CELL AND MANUFACTURING METHOD OF THE SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a unit cell of a planar solid oxide fuel cell, and to provide an electrolyte composite of a solid oxide fuel cell operable at a low temperature by improving electrical resistance and improving ion conductivity, and a method of manufacturing the same.

A fuel cell is defined as a cell that has the ability to produce direct current by converting the chemical energy of fuel (hydrogen) directly into electrical energy, and through the oxide electrolyte, oxidant (eg oxygen) and gaseous fuel (eg For example, as an energy conversion device for producing direct current electricity by electrochemically reacting hydrogen), unlike the conventional battery, it is characterized by continuously producing electricity by supplying fuel and air from the outside.

Fuel cell types include molten carbonate fuel cells (MCFCs), solid oxide fuel cells (SOFCs) operating at high temperatures, and phosphoric acid fuel cells operating at relatively low temperatures. Cell, PAFC), Alkaline Fuel Cell (AFC), Proton Exchange Membrane Fuel Cell (PEMFC), Direct Methanol Fuel Cells (DEMFC).

Solid oxide fuel cell generates electricity directly from fuel by electrochemical reaction of fuel (hydrogen) and oxygen (air) at high temperature of 600 ~ 1000 ℃, and the most power conversion efficiency (50 ~ 60%) among fuel cells In addition to the high industrial power and distributed power, small-scale power supply and small-scale Co-Gen system, the possibility of practical use is highly expected, and research and development are actively progressing around the world.

The planar solid oxide fuel cell is formed of a multi-layer stack of unit cells including an anode, an electrolyte, and a cathode. Typically, the anode is a composite of nickel oxide (hereinafter referred to as 'NiO') and yttria stabilized zirconia (hereinafter referred to as 'YSZ'), and the electrolyte is used as YSZ. A complex of silver strontium doped lanthanum manganite (hereinafter referred to as 'LSM') and YSZ is used.

Generally, YSZ is mainly used as an electrolyte, and strontium manganese doped lanthanum gallium (Lanthanum Strontium Gallate Magnesite, LSGM) (La0.9Sr0.1Ga0.8Mg0.2O2.85) is used as an electrolyte material because it has high ionic conductivity. Research is underway. In addition, a ceria-based structure, a perovskite-based structure, and an apatite-type structure may be configured as an electrolyte. However, YSZ is mainly used due to its mechanical strength and low price for p (O2).

However, conventional YSZ is formed by adding yttria to zirconia, and the charge compensation effect to maintain the total amount of charge creates an empty hole and at high temperatures, these oxygen pores form oxygen ions in the lattice. To facilitate movement. The ion conductivity of the electrolyte is determined by the concentration of oxygen vacancies and the mobility of oxygen ions. Here, increasing the content of yttria improves the ion conductivity while increasing the concentration of oxygen vacancies. However, the doping concentration of yttria has a substantially upper limit, and when the upper limit is exceeded, the ionic conductivity decreases as the oxygen ions move by the interaction of the vacancy. In addition, in order to minimize voltage loss during operation of the solid oxide fuel cell, it is advantageous that the thickness of the electrolyte is as thin as possible.

In particular, the solid oxide fuel cell operates at a high temperature of 600 ~ 1000 ℃, the research on a solid oxide fuel cell that maintains a high power density and durability while operating at a low temperature (500 ~ 800 ℃) is an important problem. However, when operating at a low temperature as described above, there is a problem in that the apparent active energy of the interfacial process is higher than the ion transport of the solid oxide electrolyte, thereby increasing the polarization phenomenon of the electrode. In order to solve this polarization phenomenon, it is necessary to increase the electrochemical activity, that is, it is important to minimize the thickness of the electrolyte and to develop an electrolyte having high ionic conductivity.

In addition, the minimum electrons contributing to the ionic conductivity in the electrolyte are greatly influenced by the partial pressure of oxygen in actual operation, and the relationship between the oxygen pressure dependence of LSGM under reduced oxygen partial pressure p (O2) and the total ion conductivity of the existing material in a reducing atmosphere is complicated. Therefore, there is a problem of reducing or decomposing ion conductivity.

Embodiments of the present invention for solving the above problems, in the production of a unit cell of a solid oxide fuel cell, an electrolyte composite of a solid oxide fuel cell that can reduce the electrical resistance of the solid electrolyte and improve the ion conductivity and a method of manufacturing the same It is to provide.

In addition, embodiments of the present invention is to provide an electrolyte composite of a solid oxide fuel cell having a thin thickness and excellent durability and a method of manufacturing the same.

According to embodiments of the present invention for achieving the above object of the present invention, a method for producing an electrolyte composite of a solid oxide fuel cell having a low electrical resistance and excellent ion conductivity, providing a porous support having a plurality of pores And depositing vanadium oxide on the support.

In an embodiment, the support may be aluminum oxide. And the vanadium oxide is deposited in the pores of the support. Here, the vanadium oxide may be deposited by an electrolytic deposition method.

For example, the support may be formed with a plurality of pores of 10 to 500nm size. In addition, the support may have a plurality of pores having a long line shape (one-dimensional form) compared to the width, it may have a form in which the plurality of pores are densely arranged in a parallel direction.

On the other hand, according to other embodiments of the present invention for achieving the above object of the present invention, the electrolyte composite of a solid oxide fuel cell with low electrical resistance and excellent ion conductivity is deposited vanadium oxide on a porous support formed with a plurality of pores Can be formed.

In an embodiment, the support may be formed of aluminum oxide, the vanadium oxide is deposited in the pores of the support, and may be deposited by electrolytic deposition.

On the other hand, according to other embodiments of the present invention for achieving the above object of the present invention, the electrolyte of the solid oxide fuel cell is formed of a porous support with a plurality of pores and an electrolyte composite in which vanadium oxide is deposited on the support Can be.

In an embodiment, a plurality of the supports and a plurality of the electrolyte composites may be formed alternately with each other. For example, a plurality of electrolyte composites may be disposed side by side such that the anode and the cathode of the solid oxide fuel cell are respectively coupled to both sides of the electrolyte composite, and the support may be interposed between the electrolyte composites.

As described above, according to the embodiments of the present invention, the electrolyte of the solid oxide fuel cell having excellent ion conductivity and low electrical resistance may be formed by electrolytically depositing vanadium oxide on a porous support having one-dimensional pores. .

In addition, the electrolyte of the solid oxide fuel cell having a thin thickness and strong durability can be formed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not limited to or limited by the embodiments. In describing the present invention, a detailed description of well-known functions or constructions may be omitted for clarity of the present invention.

Hereinafter, an electrolyte composite of a solid oxide fuel cell (SOFC) and a method of manufacturing the same will be described in detail with reference to FIGS. 1 to 4. For reference, Figure 1 is a schematic diagram of a unit cell of a solid oxide fuel cell equipped with an electrolyte according to an embodiment of the present invention. 2 to 4 are scanning electron microscope (SEM) images of an electrolyte, and FIG. 2 is an SEM image of a porous aluminum oxide support, and FIGS. 3 and 4 are SEM images of vanadium oxide deposited on the support of FIG. 2. .

The solid oxide fuel cell is formed by stacking a plurality of unit cells composed of an anode, an electrolyte, and a cathode. Here, the solid oxide fuel cell unit cell includes a process of manufacturing a cathode support electrolyte consisting of a fuel electrode and an electrolyte and a process of forming an air electrode on the anode support electrolyte.

Referring to FIG. 1, the unit cell 10 includes a fuel electrode 11 in which an oxidation reaction occurs, an air electrode 12 and an electrolyte 13 in which a reduction reaction occurs, and the electrolyte 13 is formed of a porous support 131. Vanadium oxide is formed from the deposited electrolyte composite 132.

For example, the electrolyte 13 may have a form in which the porous support 131 and the electrolyte composite 132 are alternately disposed with a plurality of porous supports 131 interposed between the plurality of electrolyte composites 132. . Here, as shown in FIG. 1, the unit cell 10 is formed by combining the anode 11 and the cathode 12 on both sides of the electrolyte 13, and the electrolyte 13 is formed of each electrolyte composite 132. The anode 11 and the cathode 12 are coupled to both sides.

Here, the porous support 131 may be a porous aluminum oxide formed with a plurality of pores 14 having a nano size. For example, as shown in FIG. 2, the porous support 131 has a plurality of pores 14 having densities of several tens to several hundreds of nanometers in size, and has a long line shape (one-dimensional shape) compared to the width. The pores 14 of) may be formed. In addition, the porous support 131 may be arranged side by side so that a plurality of pores 14 can be densely arranged with each other.

The electrolyte composite 132 is formed by depositing vanadium oxide on the porous support 131. Here, the electrolyte composite 132 is deposited to fill the vanadium oxide inside the pores 14 of the porous support 131.

The electrolyte composite 132 may be formed using an electrolytic deposition method. For example, the electrolyte composite 132 has a porous aluminum oxide support (Anodisk 25, Whatman) having a size of 200 nm and a thickness of 60 nm as an electrode, and 0.1M vanadyl sulfate (VOSO _4). ) It can be formed by immersion in the solution and applying a voltage of 1.5V (Ag / AgCl reference).

Here, the vanadium oxide is deposited according to the electrolytic deposition method, SEM images of the electrolyte composite 132 formed according to the deposition time is shown in FIGS. 3 and 4. For reference, FIG. 3 is an SEM image of the electrolyte composite 132 after 1 hour deposition, and FIG. 4 is an SEM image of the electrolyte composite 132 after 2 hours deposition. As shown in FIGS. 3 and 4, it can be seen that the vanadium oxide is densely deposited in the pores 14 of the porous support 131 as the electrolytic deposition time increases. Here, the deposition concentration of vanadium oxide is proportional to the ionic conductivity of the electrolyte 13 and the unit cell 10.

According to the present embodiment, since the vanadium oxide is deposited inside the pores 14 of the porous support 131, the ionic conductivity of the electrolyte 13 may be effectively improved without increasing the thickness of the electrolyte composite 132. It is possible to form a durable electrolyte, there is an effect that can minimize the size of the unit cell. In addition, since vanadium oxide having excellent ion conductivity is deposited inside the pores of the porous support, oxygen ions can be smoothly moved through the oxygen pores in the structure of the support, and polarization can be suppressed.

In addition, according to the present embodiment, the performance of the unit cell can be improved by suppressing an increase in electric resistance of the electrode and the electrolyte due to thermal expansion and generation of voids between the electrode and the electrolyte.

As described above, the present invention has been described by specific embodiments such as specific components and the like, but the embodiments and the drawings are provided only to help a more general understanding of the present invention, and the present invention is limited to the above-described embodiments. In other words, various modifications and variations are possible to those skilled in the art to which the present invention pertains. Therefore, the spirit of the present invention should not be limited to the above-described embodiments, and all the things that are equivalent to or equivalent to the scope of the claims as well as the claims to be described later belong to the scope of the present invention.

1 is a schematic diagram of a unit cell of a solid oxide fuel cell according to an embodiment of the present invention;

2 is a scanning electron microscope (SEM) image of a porous aluminum oxide support;

3 and 4 are SEM images of vanadium oxide deposited on the support of FIG. 2.

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

10: unit cell 11: fuel electrode

12: air electrode 13: electrolyte

131: porous support 132: electrolyte composite

14: pore

Claims (11)

Providing a porous support having a plurality of pores formed therein; And Depositing vanadium oxide on the support; Method for producing an electrolyte composite of a solid oxide fuel cell comprising a. The method of claim 1, The support is a method for producing an electrolyte composite of a solid oxide fuel cell is aluminum oxide. The method of claim 2, The vanadium oxide is a method of manufacturing an electrolyte composite of a solid oxide fuel cell deposited in the pores of the support. The method of claim 3, The vanadium oxide is a method of manufacturing an electrolyte composite of a solid oxide fuel cell is deposited by electrolytic deposition. The method of claim 1, The pores of the support is a method for producing an electrolyte composite of a solid oxide fuel cell having a size of 10 to 500nm. The method of claim 1, The pores of the support is a method of manufacturing an electrolyte composite of a solid oxide fuel cell having a long line length compared to the width. An electrolyte composite of a solid oxide fuel cell formed by depositing vanadium oxide on a porous support having a plurality of pores formed therein. The method of claim 7, wherein The support is formed of aluminum oxide, the electrolyte complex of the solid oxide fuel cell formed by depositing the vanadium oxide in the pores of the support. An electrolyte of a solid oxide fuel cell formed of a porous support having a plurality of pores and an electrolyte composite in which vanadium oxide is deposited on the support. 10. The method of claim 9, An electrolyte of a solid oxide fuel cell formed by alternately arranging a plurality of the supports and a plurality of the electrolyte composites. The method of claim 10, A plurality of electrolyte complexes are arranged side by side such that the anode and the cathode of the solid oxide fuel cell are respectively coupled to both sides of the electrolyte complex, the solid electrolyte of the solid oxide fuel cell formed by interposing the support between each electrolyte complex.

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