KR20130047175A - Preparation method of solid oxide fuel cell having ceramic granule, and a fabrication thereof - Google Patents

Abstract

PURPOSE: A solid oxide fuel cell is provided to improve interface property between electrodes by increasing a contact surface between a solid electrolyte and electrode, thereby improving battery performance. CONSTITUTION: A solid oxide fuel cell comprises a porous anode, a cathode, and a solid electrolyte thin film inserted between the anode and the cathode. Ceramic granules are located on the surface of the solid electrolyte thin film, attached to the cathode. A manufacturing method of the solid oxide fuel cell comprises a step of manufacturing the porous anode; a step of forming the solid electrolyte thin film on the porous anode; a step of spraying a ceramic raw material-containing slurry composition on the solid electrolyte thin film and forming the ceramic granules through heat-treatment; and a step of forming a porous cathode on the solid electrolyte thin film.

Description

Solid oxide fuel cell comprising ceramic granules and a method for manufacturing the same {Preparation method of solid oxide fuel cell having ceramic granule, and a fabrication etc}

The present invention relates to a solid oxide fuel cell having improved battery performance by improving an interface property between an electrolyte and an electrode, and a method of manufacturing the same.

Solid Oxide Fuel Cell (SOFC) is an eco-friendly and high-efficiency green energy that can drastically lower CO ₂ emissions in the process of converting fossil fuel into battery energy. It is emphasized more.

A solid oxide fuel cell has a solid electrolyte, an anode (fuel electrode) and a cathode (air electrode) on both sides, and an interconnecting structure (interconnect) on the outside thereof. When oxygen and hydrogen are supplied to both electrodes with the solid electrolyte interposed therebetween, an oxygen partial pressure difference is formed between the anode and the cathode, thereby driving a driving force to move oxygen through the solid electrolyte. At this time, the oxygen receives the electrons, becomes oxygen ions, passes through the electrolyte membrane, and moves to the anode. At the anode, oxygen ions release electrons and react with hydrogen gas to become water vapor. Electrical energy is generated through the emitted electrons, and the electrical energy is extracted to produce power.

The solid oxide fuel cell operates at a high temperature of 600-1000 ° C. and has the highest power conversion efficiency among existing fuel cells, and can use various fuels, and can recover heat and combine power generation using waste heat, thereby increasing system efficiency. There is an advantage to this.

Since the solid oxide fuel cell is operated at a high temperature, the component material is made of ceramic and metal, so the mechanical and chemical stability of the material is excellent, and there is no problem of loss / supplement of electrolyte. However, since battery components must be able to withstand high temperatures, the choice of materials is limited to ceramics. Even in the case of manufacturing the ceramic material, the manufacturing cost increases because the process is difficult and requires high-level technology such as well-controlled powder manufacturing technology and precise molding technology.

On the other hand, the most common method for producing an electrolyte of a solid oxide fuel cell is tape-casting, dip coating and screen-printing using a slurry prepared from a powder having a size of µm. Etc., among which RF-sputtering and electrostatic spraying methods are used.

RF-sputtering [L. Gerardo Jose et al, Microstructural Features of RF-sputtered SOFC Anode and Electrolyte Matrials, J. Elec., 13 691-695 2004], Chemical Vapor Deposition (CVD) [G. Meng et al, Novel CVD Techniques for Micro- and IT-SOFC Fabrication, Fuel Cells, 4 48-55 2004], PLD, JH Joo et al, "Electrical conductivity of YSZ film grown by pulsed laser deposition" , Thin Solid Films, 177 1053-1057 2006) and the thin film of the electrolyte using a semiconductor process such as sol-gel (sol-gel) method can be performed. In addition, the Korean Patent Application Publication No. 2011-0004274 filed by the present applicant has disclosed the production of a solid electrolyte thin film having a dense thin film structure having a thickness of less than 3㎛ by the electrostatic spraying process.

The solid electrolyte thin film manufactured by sputtering or electrostatic spraying has a dense and smooth thin film structure. In this case, the contact area between the solid electrolyte and the electrode is significantly lower in the case of an electrode contacting the solid electrolyte, particularly a porous electrode.

In order to suppress the increase in the interfacial resistance between the electrolyte and the electrode with respect to the contact area, Korean Patent Publication No. 2009-0061870 discloses an electrolyte through tape casting using nano-sized YSZ powder, thereby forming a solid oxide fuel cell. It is disclosed that the decrease in output performance can be suppressed.

In addition, the Republic of Korea Patent Publication No. 2010-0091842 is due to the nanoporous composite formed by the nanoparticles of YSZ and NiO primary particles to increase the specific surface area, in particular can have a wrinkle structure on the surface to maximize the three-phase interface It is mentioned that the performance of solid electrolyte fuel cells can be improved.

Republic of Korea Patent Publication No. 2011-0004274 Republic of Korea Patent Publication No. 2009-0061870 Republic of Korea Patent Publication No. 2010-0091842

Accordingly, an object of the present invention is to provide a solid oxide fuel cell and a method for manufacturing the same, which can improve battery performance by increasing the contact area between the solid electrolyte and the electrode, thereby improving the interfacial properties therebetween.

In order to achieve the above object, the present invention includes an anode and a cathode made of a porous thin film, and a solid electrolyte thin film interposed therebetween,

Provided is a solid oxide fuel cell, wherein ceramic granules are present on a solid electrolyte thin film in contact with the cathode.

In addition,

Preparing a porous anode,

Forming a solid electrolyte thin film on the porous anode,

In the solid oxide fuel cell manufacturing method of forming a porous cathode on the solid electrolyte thin film,

It provides a method for producing a solid oxide fuel cell comprising the step of forming a ceramic granules by electrothermal spraying and heat treatment after the slurry composition comprising a ceramic raw material powder on a solid electrolyte thin film prior to forming the porous cathode.

The solid oxide fuel cell manufactured according to the present invention is located on the electrolyte thin film to increase the contact area between the electrolyte thin film and the electrode, thereby sufficiently lowering the resistance at the interface between them, thereby greatly increasing the battery performance, especially at high temperatures. Has the effect of improving.

1 is a schematic diagram showing a solid oxide fuel cell according to the present invention.
It is a schematic diagram of the electrostatic spray apparatus used by this invention.
3 is a cross-sectional image of the solid oxide fuel cell manufactured in Example 1. FIG.
Figure 4 is an image photograph showing the ceramic granules, (a) is a side, (b) is a cross-section, (c) is an image shown from the front.
5 is a graph showing changes in voltage-current characteristics of the fuel cells obtained in Example 1 and Comparative Example 1. FIG.

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

The solid oxide fuel cell is manufactured by forming a solid electrolyte thin film on the anode and forming a cathode on the formed solid electrolyte thin film. Preferably, the electrode is manufactured to have a porous structure and the solid electrolyte has a dense thin film structure. However, in this structure, since the solid electrolyte is formed into a dense thin film, the contact area with the electrode having the porous structure in contact therewith is relatively reduced, thereby increasing the resistance at the interface.

Therefore, the present invention is structurally located in the solid electrolyte thin film so that the contact area between the solid electrolyte having a dense thin film structure and the porous electrode can be improved to improve the contact characteristics at the interface therebetween, and electrostatic spraying is performed by the manufacturing method. Thereby simplifying the process and increasing the contact area between the porous electrode and the solid electrolyte thin film.

1 is a schematic diagram showing a solid oxide fuel cell according to the present invention. Referring to FIG. 1, the solid oxide fuel cell 100 includes an anode 101 and a cathode 107, and a solid electrolyte 103 interposed therebetween, and ceramic granules 105 disposed on the solid electrolyte 103. Is formed.

The ceramic granules 105 are positioned over the entire surface of the solid electrolyte thin film 103, and the ceramic granules 105 are not present enough to form a layer. 4, it can be seen that the ceramic granules 105 are uniformly formed on the solid electrolyte thin film 103.

The ceramic granules 105 have a ball-shaped structure and have an average particle diameter of 1 to 5 μm. If the particle diameter of such ceramic granules 105 is too small or large, it is not possible to expect an appropriate interfacial property improving effect. Specifically, when the average particle diameter is less than the above range, the specific surface area of the solid electrolyte 103 thin film area due to the formation of the ceramic granules 105 may not be sufficiently increased. On the contrary, when the average particle diameter exceeds the above range, the solid electrolyte thin film may be formed by the ceramic granules 105. There arises a problem that the contact between the 103 and the cathode 107 is not made sufficiently.

As described above, the ceramic granules 105 are formed at a level not forming a layer, and the solid electrolyte 103 may be sufficiently in direct contact with the thin film of the solid electrolyte 103 and the electrode, in particular, the cathode 107. It is preferable to form within the area ratio of 10 to 80% of the total area of the thin film. If the area ratio is less than the above range, the effect of forming the ceramic granules 105 may not be sufficiently secured. If the area ratio exceeds the above range, the ceramic granules 105 may be formed on the solid electrolyte 103 thin film in a layer form. The direct contact area between the solid electrolyte 103 and the cathode 107 is reduced, resulting in a problem that the cell characteristics of the fuel cell are degraded.

In this case, the ceramic granules 105 may be uniformly distributed on the solid electrolyte 103 thin film, and may use the same or similar material as that of the solid electrolyte 103 so as to affect interfacial resistance or battery characteristics. Preferably, yttria stabilized zirconia (hereinafter referred to as 'YSZ'), ZrO ₂ system. CeO ₂ based, Bi ₂ O ₃ based, LaGaO ₃ based, ScSZ (Sc ₂ O ₃ -stabilized ZrO ₂ ), LSGM ((La, Sr) (Ga, Mg) O ₃ ) based oxide, LaMnO ₃ based, (La , Sr) MnO _3, Sr- doped LaMnO _3, LaCoO ₃ type, Sr- doped LaCrO ₃ (LSC), CeO ₂ system, Gd- doped CeO _2, Sm- doped CeO _2, SrTiO _3, Y- doped SrTiO ₃ , tungsten carbide _{(WC), La 0 .7 Sr} 0 .3 Cr 3 -δ / YSZ, Sc- doped Zr0 ₂ (100 wt%), can be one selected from the group consisting of LaGaMnOx and combinations thereof.

In the solid oxide fuel cell 100 including the ceramic granules 105, the anode 101 and the cathode 107 have a porous thin film structure, and the solid electrolyte 103 thin film has a dense structure.

At this time, the material of the anode, the cathode and the solid electrolyte (101, 107, 103) is not particularly limited in the present invention, as long as it is a material known in the art.

For example, the material of the anode 101 is Ni-YSZ-based, Ni-ScSZ-based, Ni-CeO ₂ -based, (Ni, Gd) CeO ₂ , (Ni, Sm) CeO ₂ , (Co, YSZ) CeO ₂ , _{(Co, Gd) CeO 2,} (y 1 - x Ca x) Fe 1 - y CoyO 3, (Gd 1 -x Sr x) sFe 1-y CoyO 3 or _{(Gd 1 - x Cax) sFe} 1 - y CoyO One selected from the group consisting of ₃ and a combination thereof is possible, preferably using a GDC (Gd-doped CeO ₂ ) system, consisting of a porous thin film having a thickness of 0.1 to 1.0mm.

Cathode 107 is LaMnO ₃ based, Sr-doped LaMnO ₃ (LSM), LaCoO ₃ based, Sr-doped LaCoO ₃ (LSC), Sr, Fe-doped LaCoO ₃ (LSCF) SrCoO ₃ based, Sm-doped SrCoO ₃ (SSC) Ba _0.5 Sr _0.5 Co _0.8 Fe _0.2 O ₃ (BSCF) and one selected from the group consisting of a mixed composition with the electrolyte material is possible, preferably using a BSCF, thickness of 0.1 to 1.0mm It consists of a porous membrane having. CeO ₂ system, Gd- doped CeO _2, Sm- doped CeO _2, SrTiO _3, SrTiO ₃ doped Y-, tungsten carbide _{(WC), La 0 .7 Sr} 0 .3 Cr 3 -δ / YSZ, Gd or Sm- Doped cerium oxide (less than 10 to 100% by weight), Sc-doped Zr0 ₂ (below 100% by weight), LaGaMnOx and one selected from the group consisting of these can be selected, preferably using LaMnO ₃ , 0.1 to It consists of a porous thin film with a thickness of 1.0 mm.

In addition, the solid electrolyte 103 is YSZ, ZrO ₂ system. Group consisting of CeO ₂ based, Bi ₂ O ₃ based, LaGaO ₃ based, ScSZ (Sc ₂ O ₃ -stabilized ZrO ₂ ), LSGM ((La, Sr) (Ga, Mg) O ₃ ) based oxides and mixtures thereof It is possible to select one species selected from, preferably using a GDC, to form a thin film of 5㎛ or less.

The anode, the cathode and the solid electrolyte 101, 107, 1033 can be formed of a single layer thin film or a multilayer thin film as known, including the above-mentioned materials.

The solid oxide fuel cell 100 including these is not particularly limited in the present invention, by preparing a slurry composition for forming an anode on a substrate, a deposition process such as wet coating, sputtering, such as tape casting, dip coating, and screen coating, or Electrostatic spraying is possible.

In particular, the ceramic granules 105 may not be formed through the wet coating or sputtering, and may be formed by performing electrostatic spraying.

Specifically, in the solid oxide fuel cell according to the present invention, a porous anode is prepared, a solid electrolyte thin film is formed on the porous anode, and a slurry composition including ceramic raw material powder on the solid electrolyte thin film is subjected to electrostatic spraying and then heat treatment. After forming the ceramic granules through, it is prepared by forming a porous cathode on top.

Hereinafter, the manufacturing method will be described in detail.

First, an anode used for a solid oxide fuel cell is prepared.

At this time, the production of the anode can be made in a variety of ways, preferably by uniaxial compression molding using the powder for forming the anode.

Next, a solid electrolyte thin film is formed on the anode.

The formation of a solid electrolyte thin film may also be a well-known method. Preferably, the solid electrolyte thin film may be manufactured by electrostatic spraying to obtain a dense thin film having a thickness of 5 μm or less. In particular, when the solid electrolyte thin film is also produced by the electrostatic spray method, since the ceramic granules formed on the electrostatic spray method can also be carried out through the same apparatus and method, there is an advantage that the process is simple.

Next, ceramic granules are formed on the solid electrolyte thin film.

Ceramic granules may be prepared through electrostatic spraying and heat treatment on a solid electrolyte thin film using a slurry composition containing a ceramic raw material powder.

In this case, the slurry composition includes various compositions such that the ceramic raw material powder forms a stable dispersed phase and is suitable for electrostatic spraying together with the ceramic raw material powder to form ceramic granules having a ball shape and having a micro level particle diameter.

In particular, the ceramic raw material powder uses an average particle diameter of nano level, preferably 10 nm to 900 nm, preferably 10 to 500 nm. The nano-level ceramic raw material powder can be prepared into ball-shaped granules through recombination between powders through electrostatic spraying and heat treatment. Such particle size limitation can be carried out through conventional milling processes such as, for example, ball mill processes. The ball mill apparatus that can be used in the ball mill process is not particularly limited in the present invention, and typically, an attritor, a 3-D mixer, a planetary ball mill, a vibratory ball mill, a horizontal ball mill Various ball mills are available, including horizontal ball mills.

Various additives may be used to prepare a slurry composition for applying the ceramic raw material powder to an electrostatic spray method, and include, for example, a dispersant for increasing dispersion stability, a binder, and a solvent for dispersion, and additionally, forming droplets during electrostatic spraying. And additives such as surfactants and plasticizers. The solvent, the dispersant, the binder, and the additive are removed by heat treatment after coating on the substrate, and by this removal, recombination between the nanopowders is performed to form ceramic granules.

As the dispersant, one kind selected from the group consisting of fish oil, phosphoric acid ester, polyethylene glycol ether, alkyl sulfonate, polycarboxylate, alkyl ammonium salt, hypermerkaid (Hypermer ™ KD), and combinations thereof, Preferably, KD-15 is used in the hypermeradiide system.

The surfactant is used together with the dispersant to form the raw powder into smaller droplets in the spraying step and to improve dispersion stability in the slurry composition. The surfactant is not particularly limited in the present invention, but a nonionic surfactant is preferable, and one selected from the group consisting of Tween-20, Triton X-100, and combinations thereof is used, and preferably Triton X- 100 is used.

The binder is used for the purpose of increasing the bonding strength or adhesion between the nanopowders and the ceramic granules made of the nanopowders and the thin layer of the solid electrolyte. The binder is selected from the group consisting of PVB (polyvinyl butyral), PVA (polyvinyl alcohol), ethyl hydroxyethyl cellulose, and combinations thereof, and preferably PVB is used.

Plasticizers, together with dispersants, use ceramic powders for the formation of smaller droplets in the electrostatic spraying step, typically glycerol, ethylene glycol, polyethylene glycol, bis 2-ethylhexyl sebacate, dioctylphthalate, triphenylphosphate, As the solvent used as the dispersion medium of the slurry composition using one selected from the group consisting of trioyl phosphate, butyl benzyl phthalate, dibutyl phthalate, polyethylene glycol dimethyl ether, dimethylformamide, and a combination thereof, a non-aqueous solvent may be used. Such non-aqueous solvents are selected from the group consisting of cyclic carbonates, chain carbonates, cyclic esters, chain esters, cyclic ethers, chain ethers, sulfur-containing organic solvents, and combinations thereof. 1 type is used. Preferably, the non-aqueous solvent may be ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

In addition, an aqueous solvent may be used, and the aqueous solvent may be methanol, ethanol, isopropanol, toluene, water, or a mixed solvent thereof. Preferably, an isopropanol or toluene mixed solvent is used.

The composition of the ceramic raw material powder, dispersant, surfactant, binder, plasticizer and solvent constituting the slurry composition must be controlled so that the composition can exert the effect of each composition to be suitable for the electrostatic spray process as well as the selection of the composition. In other words, since the dispersion properties of each slurry composition and the morphology of the ceramic granules may vary according to the type of each composition, the optimal composition selection is important, which may be appropriately selected and selected within the composition and content ranges described above.

Preferably, the slurry composition is 0.1 to 10 parts by weight of dispersant, 0.1 to 10 parts by weight of surfactant, 1 to 25 parts by weight of binder, 0.1 to 10 parts by weight of plasticizer, and 100 to 500 parts of aqueous solvent based on 100 parts by weight of ceramic raw material powder. It includes parts by weight.

When the content of the dispersant in the slurry composition is less than the above range, the ceramic raw material powder is not uniformly dispersed in the slurry composition, so that phenomena such as agglomeration, agglomeration or precipitation in each slurry composition occur and cause nozzle clogging in the electrostatic spraying process. . On the contrary, even if it exceeds the said range, since cost-effectiveness does not increase significantly, it uses suitably within the said range.

In addition, when the content of the binder in the slurry composition is less than the above range, the adhesion of the ceramic powder to the surface of the substrate after spraying is lowered. When the content of the binder exceeds the above range, the heat treatment temperature and time are not only increased for the use of the binder higher than necessary. There exists a possibility to remain in porous oxide particle.

In particular, when the surfactant is used only in the slurry composition, if the content is less than the above range, the dispersing property of the raw material powder is poor, and phenomenon such as aggregation, agglomeration or precipitation in the slurry composition occurs. On the contrary, even if it exceeds the said range, since cost-effectiveness does not increase significantly, it uses suitably within the said range. In addition, when the content of the plasticizer is less than the above range, the dispersion stability of the slurry composition is lowered. On the contrary, even if the content of the plasticizer exceeds the above range, the cost-effectiveness does not increase significantly.

A conventional method may be used to prepare the slurry composition. For example, a solvent, various additives (surfactant, dispersant, plasticizer, binder, and the like) are mixed in a mixer, and then ceramic powder (eg, YSZ or LSM) is added. By mixing evenly.

In particular, since the slurry composition according to the present invention has a particle size of nano-level powder, it is very important to disperse the particles into individual particles. Therefore, selection of the type and content of the dispersant and the binder is very important to achieve complete dispersion. . The dispersant-binder showed high dispersion stability when used in combination with fish oil-PVA, or KD15-PVB, of which KD15-PVB had the highest solubility and showed the most stable slurry dispersibility.

The electrostatic spraying process may use a conventional electrostatic spraying device, and may be preferably performed using the apparatus as shown in FIG. In this case, another device may be inserted into each component by a person skilled in the art in the device of FIG. 2.

In particular, in the present invention, it is possible to obtain ceramic granules in the form of a ball through a top-down spraying method in which the slurry composition is sprayed downward in the case of electrostatic spraying. According to the experiments of the present inventors, when the apparatus is installed in a bottom-up manner, ceramic granules can be obtained, but particle size is not uniform.

The apparatus for the electrostatic spray method shown in FIG. 1 includes an electrostatic spray chamber 10, a slurry composition reservoir 11, a nozzle 12, a syringe pump 13, a potential difference generator 14, a substrate 15, a substrate. Holder 16, temperature controller 17, and step motor 18.

First, the structure in which the solid electrolyte thin film is formed on the porous anode prepared in the previous step is used as the substrate 15 and mounted on the substrate holder 16.

Then, after injecting the slurry composition for forming ceramic granules into the slurry composition reservoir 11, the slurry composition in the slurry composition reservoir 11 is transferred to the nozzle 12 by pressurization using a syringe pump 13 to discharge the electrostatic force. Perform the spraying process.

The nozzle 12 preferably has a cylindrical shape for forming droplets and a long, thin capillary shape along the inside. At this time, the nozzle 12 uses a diameter of 0.01 ~ 1.0 mm, preferably 0.31 mm to form a micron droplets. The diameter of the nozzle 12 can be modified by suitably considering the applied voltage, the concentration of the slurry composition, and the like.

Spraying using the nozzle is possible in the conventional dripping mode, cone-jet mode, multi-jet mode. At this time, the dripping mode is sprayed by dropping by gravity, and the cone-jet mode is performed in such a way that the atomization is uniformly atomized by the overall uniform droplets, and the multi-jet mode generates a larger DC voltage in the cone-jet mode. It is a mode that is formed when applied to the nozzle, is divided into two or more spraying method. In the present invention, it is preferable to carry out in the multi-jet mode in order to obtain in the form of porous granules, and more preferably, it is effective to maintain the multi-jet forming 4 to 6 spray stems.

The nozzle 12 is connected to a potential difference generating device 14 for generating an electric field. This potential difference generating device 14 allows the slurry composition to be charged with a positive charge when the ground flows in a negative charge.

Next, a droplet is formed by spraying the slurry composition using the nozzle 12, and the droplet is adsorbed on the surface of the substrate 15. Next,

At this time, droplets of finer and uniform size can be formed by the electric field formed in the chamber, and the size can be controlled by adjusting the voltage. For example, the larger the voltage, the smaller the droplet, and in order to form a micron level droplet, the voltage is applied at 1-20 kV, preferably 5-18 kV.

The droplet size is proportional to the flow rate of the slurry composition (AM Ganan-Calvo, J. Aerosol. Sci. 28,249, 1997), and the larger the flow rate of the solution, the larger the droplet size is and the removal of solvent in the droplets through drying. Ceramic granules are formed.

At this time, the substrate 15 is arranged to be spaced apart from the nozzle 12 by a predetermined distance, that is, the morphology of the porous oxide particles formed according to the distance between the nozzles and the substrates 12 and 15 is different. Preferably, the distance from the nozzle-substrate 12 and 15 is adjusted to be 1 to 10 cm.

The substrate support 16 also connects with the stepper motor 18 so that the droplets transferred through the spray can be evenly distributed on the substrate 15. The step motor 18 is a device that enables reciprocation, vibration, and rotational movement about one axis. The step motor 18 adsorbs droplets on the substrate 15 with a uniform thickness.

The deposition time through the spray affects the physical properties of the finally obtained porous oxide particles. As the deposition time is increased, it can be seen that the thickness of the layer made of porous ceramic granules increases linearly and can be easily controlled only by adjusting the deposition time.

The electrostatic spray method is carried out by spraying the slurry composition through a nozzle in an electric field atmosphere, wherein the distance between the substrate and the nozzle is 1 ~ 10cm, slurry flow rate is 0.1 ~ 10ml / h, DC voltage is 1 ~ 20kV, spraying time is 1 minute Perform for 60 minutes. Preferably, the distance between the substrate and the nozzle is 5 to 8 cm, the slurry flow rate is 4 to 6 ml / h, the DC voltage is 5 to 10 kV, and the deposition time is performed for 0.1 to 20 minutes.

Next, the droplets adsorbed on the substrate 15 are dried and heat treated to remove solvents and by-products contained in the droplets, thereby forming ceramic granules.

Drying is preferably carried out at room temperature and this drying process may be carried out through a separate drying device, in the present invention is carried out by heating the substrate 15.

In particular, the heat treatment is carried out at a sufficiently high temperature so that the ceramic granules have a dense structure, can be sufficiently formed on the solid electrolyte thin film in the form of balls and can be supported by the solid electrolyte thin film with high adhesion. The heat treatment is carried out for 1 to 3 hours at 200 ~ 1400 ℃, at this time can change the heat treatment temperature according to the material. In particular, at a low heat treatment temperature, the organic material is not sufficiently removed and the ceramic granules are obtained in a porous structure rather than a dense structure, so they are performed at a relatively high temperature. In this case, the heat treatment may be performed by controlling the temperature of the temperature controller 16 in the electrostatic spray chamber 10 or by transferring to a separate heat treatment apparatus.

The ceramic granules formed on the substrate 15 through the above steps have a ball shape having a particle diameter of 1 to 5 μm, and have a dense structure without pores. In this case, if the ceramic granules are porous granules with pores rather than a dense structure, the interfacial properties between the electrolyte and the cathode may be increased. As a result, the effect of reducing the interface resistance between the solid electrolyte and the cathode cannot be sufficiently exhibited.

As described above, the ceramic granules according to the present invention can control the morphology of the ceramic granules by adjusting the applied voltage during electrostatic spraying, the distance from the nozzle-substrate, the substrate temperature, the spraying time, and the heat treatment temperature. In addition, the use of simple equipment and processing at room temperature and atmospheric pressure makes the process easier and significantly reduces manufacturing costs.

Next, a cathode is formed over the entire solid electrolyte thin film including the ceramic granules.

In this case, the cathode preferably has a porous structure, which may also be manufactured through an electrostatic spray method such as a solid electrolyte thin film.

In the solid oxide fuel cell according to the present invention manufactured by the above-described method, the contact area between the electrolyte thin film and the electrode is increased, so that the resistance at these interfaces is reduced, resulting in improved performance of the fuel cell.

According to the experimental example of the present invention, the fuel cell in which the ceramic granules were formed showed an improvement in voltage-current characteristics compared to the fuel cell that was not formed, and in particular, it was confirmed that the effect is improved even at a temperature of 400 ~ 800 ℃.

[Example]

Hereinafter, preferred examples and experimental examples of the present invention are presented. However, the following examples are only preferable examples of the present invention, and the present invention is not limited to these examples.

Example  One

Carbon black was mixed with NiO, GDC, and a pore former in a weight ratio of 6: 4: 0.1, and then uniaxially press-molded into a disk-shaped substrate to prepare a porous anode (thickness of about 1000 μm).

Electrostatic spraying was performed on the anode to form a GDC ceramic electrolyte thin film (thickness 10 μm) having a dense thin film structure, and GDC ceramic granules were formed thereon. Subsequently, the porous cathode BSCF was coated over the entire surface of the GDC ceramic electrolyte thin film on which the GDC ceramic granules were formed by electrostatic spraying in the same manner to prepare a solid oxide unit cell having a Ni-GDC / GDC / granular GDC / BSCF structure. At this time, Pt paste was used as the current collector.

The ceramic electrolyte thin film, the ceramic granules, and the cathode were prepared through the electrostatic spraying process using the apparatus of FIG. 1 after preparing each slurry composition, wherein the composition and the electrostatic spraying conditions are shown in Table 1 below.

Slurry composition Electrostatic spraying conditions Solid electrolyte thin film 5 g of GDC powder
50 ml of isopropyl alcohol / toluene (7: 3),
0.5 g of polyvinyl butyral Slurry flow rate: 5mL / h
Applied voltage: 10kV
Nozzle-Board Distance: 7cm
Spray time: 20 minutes
Drying: room temperature, 2 hours
Heat treatment: 1400 ℃, 3 hours Ceramic granules 5 g of GDC powder
50 ml of isopropyl alcohol / toluene (7: 3),
Triton X-100: 0.6g
Fish oil: 0.6 g
PVB Binder: 1.5g Slurry flow rate: 6mL / h
Applied voltage: 12kV,
Nozzle-Board Distance: 5cm
Spray time: 10-30 seconds
Drying: room temperature, 2 hours
Heat treatment: 1400 ℃, 1 hour Cathode _{Ba 0 .5 Sr 0 .5 Co 0} .8 Fe 0 .2 O 3 -δ powder 5g
Isopropyl alcohol / toluene (7: 3): 50 ml,
Polyvinyl Butyral: 0.5g Slurry flow rate: 5mL / h
Applied voltage: 10kV
Nozzle-Board Distance: 7cm
Spray time: 20 minutes
Drying: room temperature, 2 hours
Heat treatment: 1150 ℃, 2 hours

Comparative example  One

A solid oxide fuel cell was manufactured in the same manner as in Example 1 except for ceramic granules.

Experimental Example  1: Scanning Electron Microscope Analysis

Images of the solid oxide fuel cell prepared in Example 1 were measured using a scanning electron microscope, and the obtained results are shown in FIGS. 2 and 3.

3 is a cross-sectional image of the solid oxide fuel cell prepared in Example 1, the cathode and the anode is a porous structure, it can be seen that the solid electrolyte thin film is formed in a dense structure.

Figure 4 is an image showing the ceramic granules, as shown in Figure 4 (a) it can be seen that the ceramic granules are formed in a ball shape on the solid electrolyte thin film. At this time, the ball size is about 3.5㎛ level can be seen that the particle size is almost uniform.

In addition, as shown in (b) of FIG. 4, the interface between the solid electrolyte thin film and the ceramic granules is not clearly present, and thus, the ceramic granules are formed on the solid electrolyte thin film with high adhesion.

And, as shown in Figure 4 (c), the ceramic granules are evenly distributed over the entire surface of the solid electrolyte thin film, it can be seen that does not form a layer (layer). In addition, when the area ratio was measured using an image program (photoshop), it was confirmed that the ceramic granules were present in the area ratio of about 25% with respect to the solid electrolyte thin film in the area of 10 × 5 cm 2.

Experimental Example  2: unit cell evaluation

Using the fuel cells prepared in Example 1 and Comparative Example 1 was evaluated the battery characteristics according to the temperature change, the results are shown in FIG.

FIG. 5 is a graph showing a change in voltage-current characteristics of the fuel cells obtained in Example 1 and Comparative Example 1, wherein the battery characteristics of Example 1 in which ceramic granules were formed were improved by up to 35.7%.

In particular, the high performance of about 12.4% at high temperature 750 ℃ and 35.7% at low temperature 550 ℃ has proved that it can be used as a low-temperature and high-temperature solid oxide fuel cell.

The solid oxide fuel cell according to the present invention exhibits excellent battery characteristics not only at low temperatures but also at high temperatures, and thus can be used as a solid oxide fuel cell in all temperature ranges, particularly in the temperature range of 400 to 800 ° C.

10: electrostatic spray chamber 11: slurry composition reservoir
12: nozzle 13: syringe pump
14: potential difference generator 15: substrate
16: substrate holder 17: thermostat
18: step motor

Claims (15)

An anode and a cathode made of a porous thin film, and a solid electrolyte thin film interposed therebetween,
Solid oxide fuel cell, characterized in that the ceramic granules on the solid electrolyte thin film in contact with the cathode. The ceramic granules of claim 1, wherein the ceramic granules are yittria stabilized zirconia (YSZ), scandia stabilized zirconia (SCSZ), gadolinium doped ceria (GDC), samarium doped ceria (SDC), and ZrO ₂ based. CeO ₂ based, Bi ₂ O ₃ based, LaGaO ₃ based, ScSZ (Sc ₂ O ₃ -stabilized ZrO ₂ ), LSGM ((La, Sr) (Ga, Mg) O ₃ ) based oxides, BaCeO ₃ , Ba (Sm A solid oxide fuel cell comprising one selected from the group consisting of, Gd, Y) CeO ₃ , BaZrO ₃ , Ba (Ce, Zr, Y) O _3, and a combination thereof. The solid oxide fuel cell of claim 1, wherein the ceramic granules have an average particle diameter of 1 μm to 5 μm. The solid oxide fuel cell of claim 1, wherein the ceramic granules are present in an area ratio of 10 to 80% on the surface area of the solid electrolyte thin film. The method of claim 1, wherein the solid oxide battery
Gadolinium doped ceria (NiO-GDC) anodes; _{BSCF (Ba 0 .5 Sr 0 .5} Co 0 .8 Fe 0 .2 O 3) cathode; GDC electrolyte thin film; And GDC ceramic granules having a size of 1 to 5 μm on the electrolyte thin film. Preparing a porous anode,
Forming a solid electrolyte thin film on the porous anode,
In the solid oxide fuel cell manufacturing method of forming a porous cathode on the solid electrolyte thin film,
And forming ceramic granules through electrothermal spraying and thermally treating the slurry composition including the ceramic raw material powder on the solid electrolyte thin film before forming the porous cathode. The method of claim 6, wherein the slurry composition is 0.1 to 10 parts by weight of dispersant, 0.1 to 10 parts by weight of surfactant, 1 to 25 parts by weight of binder, 0.1 to 10 parts by weight of plasticizer, and 100 solvents based on 100 parts by weight of ceramic raw material powder. Method for producing a solid oxide fuel cell, characterized in that it comprises from 500 parts by weight. The method for manufacturing a solid oxide fuel cell according to claim 6, wherein the ceramic raw material powder of the ceramic granules has an average particle diameter of 10 nm to 900 nm. The method of claim 7, wherein the dispersing agent is selected from the group consisting of fish oil, phosphate ester, polyethylene glycol ether, alkyl sulfonate, polycarboxylate, alkyl ammonium salt, hypermercade (KD) and combinations thereof A method for producing a solid oxide fuel cell, characterized in that one kind. The method of claim 7, wherein the surfactant is one selected from the group consisting of Tween-20, Triton X-100, and a combination thereof. The method of claim 7, wherein the binder is one selected from the group consisting of polyvinyl butyral, polyvinyl acetal, polyethylene, polypropylene, polystyrene, polyvinyl alcohol, polybutyl acetate, polyvinylpyrrolidone, and combinations thereof. A method of manufacturing a solid oxide fuel cell, characterized in that. The method of claim 7, wherein the plasticizer is glycerol, ethylene glycol, polyethylene glycol, bis 2-ethylhexyl sebacate, dioctyl phthalate, triphenyl phosphate, tri yl phosphate, butyl benzyl phthalate, dibutyl phthalate, polyethylene glycol dimethyl ether, Method for producing a solid oxide fuel cell, characterized in that one selected from the group consisting of dimethylformamide and combinations thereof. The method of claim 7, wherein the solvent is a non-aqueous solvent including methanol, ethanol, isopropanol, ethylene glycol, or a combination thereof; And one selected from the group consisting of a combination thereof. The method of claim 6, wherein the electrostatic spraying method is carried out by spraying through a nozzle having a diameter of 0.01 ~ 1.0 mm in an electric field atmosphere, wherein the distance between the substrate and the nozzle is 1 ~ 10cm, slurry flow rate is 0.1 ~ 10ml / h, DC voltage Silver 0.1-20kV, spraying time is 0.1 minutes to 10 minutes of manufacturing a solid oxide fuel cell, characterized in that carried out. The method of claim 6, wherein the heat treatment is performed at 200 to 1400 ° C. for 1 to 3 hours.

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