WO2023038167A1 - Metal-supported solid oxide fuel cell comprising contact layer - Google Patents

Abstract

Provided is a metal-supported solid oxide fuel cell comprising a contact layer. Provided is a metal-supported solid oxide fuel cell comprising a contact layer, the solid oxide fuel cell comprising a metal support, and a contact layer, an anode layer, an electrolyte layer, and a cathode layer which are sequentially laminated on the upper portion of the metal support, wherein the contact layer is inserted in a cell of the fuel cell so as to reduce a difference in microstructure between the layers, and a gradient is applied in terms of microstructure so as to increase lifespan and improve heat cycle properties.

Description

Metal support type solid oxide fuel cell including a contact layer

The present invention relates to a solid oxide fuel cell (SOFC), and more particularly, to a metal support type solid oxide fuel cell including a contact layer.

The metal supported solid oxide fuel cell is a new concept solid oxide fuel cell that can increase mechanical strength and sealing efficiency by reducing the thickness of ceramic elements by using metal as a support instead of the anode of the current anode supported fuel cell. . In the metal support type solid oxide fuel cell, the metal support serves as a separator of the ceramic support type fuel cell, so that at least the sealing problem between the fuel electrode and the separator can be solved. In addition, since the metal processing process is easier to access than the ceramic processing process, fuel cell performance can be improved through passage processing, etc., and manufacturing costs are expected to be significantly reduced.

In addition, since the metal-supported solid oxide fuel cell is resistant to thermal and mechanical shock and enables a rapid thermal cycle, the thermal and mechanical reliability, which are weaknesses of existing solid oxide fuel cell stacks and systems, are greatly improved to commercialize solid oxide fuel cells. can make it possible.

In the manufacturing method of the metal support type solid oxide fuel cell, co-firing (co- There is a way to fire).

However, the method precisely controls the thermal expansion coefficient, sintering shrinkage, etc. of each of the solid electrolyte layer, the anode layer and the metal support, and the metal composition, particle size, surface roughness, and firing atmosphere so that the metal support has sufficient porosity even after co-firing at a high temperature. There is a problem that must be precisely controlled. In addition, in the case of a fuel cell manufactured by this manufacturing method, since sintering shrinkage of the substrate does not occur during sintering, in the wet powder process, the thin metal plate interferes with the shrinkage of the solid electrolyte layer, resulting in remaining pores and cracking due to local sintering. When a crack occurs, there is a problem in that a crossover phenomenon occurs when the anode gas and air meet through the solid electrolyte layer.

The problem to be solved by the present invention is to insert a contact layer between the metal support and the anode layer in order to prevent a gas flow difference and a large strain between the layers due to the microstructure difference between the metal support and the anode layer, thereby changing the microstructure. It is to provide a metal support type solid oxide fuel cell in which is relaxed.

The technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

In order to achieve the above technical problem, one aspect of the present invention provides a metal support type solid oxide fuel cell including a contact layer. A metal support type solid oxide fuel cell is stacked on a metal support, a contact layer stacked on top of the metal support and acting as a buffer in terms of microstructure while passing gas and electricity, and stacked on top of the contact layer, ionized oxygen ions and injection A fuel electrode layer that combines hydrogen to produce water and electrons, a solid electrolyte layer stacked on top of the fuel electrode layer, and preventing mixing of hydrogen and air while allowing oxygen ions to pass through, and stacked on top of the solid electrolyte layer, A cathode layer for reducing injected air to produce oxygen ions may be included.

A protective layer may be included between the electrolyte layer and the cathode layer.

The protective layer may include Ce _1-y Ln _y O _2-β (Ln = Gd, Sm, Nd or La, y = 0.1 to 0.3, β = 0 to 0.2).

A current collector stacked on top of the cathode layer may be included.

The metal support may be any one of Ni metal, Ni-Fe alloy, and STS (Stainless Steel) system.

The anode layer may be a composite of NiO and rare earth-doped zirconia or a composite of NiO and rare earth-doped ceria.

The fuel electrode layer is a perovskite oxide And CeO ₂ It further includes any one or more of, wherein the perovskite oxide is A' _x B' _y O ₃ (where, 0≤x≤1, 0≤y≤1, A'= La, Sr, At least one of Ba, Pr, and Sm; B' = at least one of Ti, Y, Sc, Cr, V, Mn, Co, Fe, Ni, Mo, Nb, Al, Mg, and Ca).

The composition of the cathode layer includes a perovskite-based oxide, and the perovskite-based oxide is A' _x B' _y O ₃ (where 0≤x≤1, 0≤y≤1, and A'= La , Sr, Ba, Pr, or Sm; B'=Ti, Y, Sc, Cr, V, Mn, Co, Fe, Ni, Mo, Nb, Al, Mg, or one or more of Ca).

The cathode layer may further include at least one of a sintered powder mixture of rare earth-doped ceria and a pore former.

The electrolyte layer may be any one of a rare earth-doped zirconia-based oxide, a rare earth-doped ceria-based oxide, and a perovskite-based oxide.

The perovskite-based oxide may be La _1-x A _x Ga _1-y B _y O ₃ (A=Sr, Ba; B=Mg, Ca).

The contact layer may be a mixture of components of the metal support and components of the anode layer.

The metal support component of the contact layer and the anode layer component may have a composition ratio of 7:3 to 3:7.

An average particle size of the contact layer may be 0.3 μm to 30 μm.

The thickness of the contact layer may be 5 μm to 50 μm.

The thermal expansion coefficient of the contact layer may be 10 (ppm/℃) to 20 (ppm/℃).

As described above, according to the present invention, since the contact layer exists between the metal support layer and the fuel electrode layer, the difference in microstructure caused by the difference in density and particle size between the metal support layer and the fuel electrode layer is alleviated, thereby reducing the difference between the layers. The stability of the fuel cell may be improved by relieving deformation and facilitating gas flow. In addition, the contact layer serves as a buffer to alleviate a difference in thermal expansion coefficient between the metal support layer and the fuel electrode layer, thereby suppressing the peeling phenomenon between layers.

1 is a schematic diagram showing the structure of a metal support type solid oxide fuel cell including a contact layer according to an embodiment of the present invention.

2 is a cross-sectional view comparing microstructures of Ni-based metal support type solid oxide fuel cells before and after reduction.

3 is a cross-sectional view comparing microstructures of STS-based metal-supported solid oxide fuel cells.

4 is a radius of curvature formed when a contact layer or an anode layer is respectively stacked on a metal support.

Hereinafter, in order to explain the present invention in more detail, preferred embodiments according to the present invention will be described in more detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms.

The terminology used in this specification is only for referring to the examples and is not intended to limit the present invention. As used herein, the singular forms also include the plural forms unless the phrases clearly indicate the opposite. As used herein, the meaning of “comprising” specifies specific characteristics, regions, integers, steps, operations, elements, and/or components, and the presence of other specific characteristics, regions, steps, operations, elements, components, and/or groups. I am not excluding additions.

In addition, all terms including technical terms and scientific terms used in this specification have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. Terms defined in commonly used dictionaries are additionally interpreted as having meanings consistent with related technical literature and currently disclosed content, and are not interpreted in ideal or very formal meanings unless defined.

In the figures herein, the thicknesses of layers and regions are exaggerated for clarity. Like reference numbers indicate like elements throughout the specification.

Solid oxide fuel cell including a contact layer

1 is a schematic diagram showing the structure of a metal support type solid oxide fuel cell including a contact layer according to an embodiment of the present invention. Referring to FIG. 1, in the metal support type solid oxide fuel cell 10 including the contact layer, the contact layer 12 is stacked on the metal support 11, and the fuel electrode layer 13 is stacked on the top. The solid electrolyte layer 14 may be stacked on top of the anode layer, and the cathode layer 16 may be stacked on top of the solid electrolyte layer. In addition, a protective layer 15 may be stacked between the solid electrolyte layer 14 and the cathode layer 16 , and a current collector 17 may be stacked on the cathode layer 16 .

The metal support 11 has a small reduction in electrical conductivity due to high-temperature oxidation, has oxidation-reduction stability (redox stability), and has a thermal expansion coefficient of 5 (ppm / ℃) to 20 (ppm / ℃), specifically 10 (ppm / ℃) to 15 (ppm / ℃) is preferred. The reason for limiting the thermal expansion coefficient of the metal support in this way is to reduce the difference in thermal expansion coefficient between the metal support and each ceramic functional layer laminated thereon to prevent peeling of the functional layer or warping of the cell due to the difference in thermal expansion coefficient between each component. am.

Materials for metal supports having such characteristics include any one of Ni, Ni-Fe alloy, and STS (Stainless Steel) system, and the STS system may be, in particular, ferritic stainless steel. There are STS434L and Crofer22H, product name of Tyssenkrupp of Germany.

According to one embodiment of the present invention, the contact layer 12 may be stacked on the metal support 11, and the anode layer 13 may be stacked on the contact layer 12.

In the anode layer 13 , hydrogen injected from the outside and ionized oxide ions transferred from the solid electrolyte layer 14 are combined to generate water and electrons. The ceramic precursor powder, which is a component constituting the fuel electrode layer 13, is a composite of NiO and rare earth-doped zirconia (Zr _1-x D _x O ₂ (D = Y, Sc, La, Ce, Pr, Nd, Pm, Sm) , Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu; x=0.1∼0.3) or NiO and rare earth-doped ceria (Ce _1-x D _x O ₂ (D= Y, Sc, La , Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu; x=0.1∼0.3))). In addition, at least one of a perovskite-based oxide and CeO ₂ may be further included in the composite. At this time, the perovskite-based oxide is A' _x B' _y O ₃ (provided, 0≤x≤1, 0≤y≤1, and A'= one or more of La, Sr, Ba, Pr, Sm; B'=Ti, Y, Sc, Cr, V, Mn, Co, Fe, Ni, Mo, Nb, Al, Mg, Ca) may be one or more), specifically La _1-x A _x Ga _1-y B _y O ₃ (A=Sr, Ba; B=Mg, Ca).

According to an embodiment of the present invention, the composition ratio of nickel (Ni) and rare earth-doped zirconia in the anode layer 13 may be 6:4 to 4:6, specifically 5.5:4.5 to 4.5:5.5. It may be, and more specifically, it may be 5:5.

On the other hand, the perovskite is a structural compound in the form of ABO ₃ , the A site is occupied by one or more of lanthanum (La), Sr, Ba, Sm, and Pr elements, and the B site is manganese ( Mn), Ti, Cr, V, Ni, Co, Fe, Al, Nb, Mo Mg, and Ca may be formed by mixing some or all of the elements.

According to one embodiment of the present invention, it is suitable that the average thickness of the anode layer 13 ranges from 5 to 50 μm, more preferably from 10 μm to 30 μm, and still more preferably from 15 μm to 25 μm.

The contact layer 12 functions as a buffer in terms of microstructure while passing gas and electricity. Specifically, the metal support 11 and the fuel electrode layer 13 have a large difference in density and particle size, which can cause a gas flow difference and large strain between layers. Therefore, by positioning the contact layer 12 between the metal support 11 and the anode layer 13, a buffering function of alleviating the microstructural difference can be performed. In addition, the contact layer 12 may play a role of suppressing an interlayer peeling phenomenon due to a difference in thermal expansion coefficient between the metal support 11 and the anode layer 13 .

In this case, the composition of the contact layer 12 may be a mixture of the components of the metal support 11 and the components of the anode layer 13 . Specifically, the component of the contact layer 12 may be a mixture of NiO ₂ or Crofer 22H, which is a component of the metal support 11, and rare earth-doped zirconia, which is a component of the anode layer 13. At this time, the composition ratio of the components of the metal support 11 and the components of the fuel electrode layer 13 in the contact layer 12 may be 9:1 to 3:7, in detail 8:2 to 4:6 It may be, and more specifically, it may be 7:3 to 6:4.

It is suitable that the average thickness of this contact layer 12 ranges from 5 μm to 50 μm, more preferably from 20 μm to 40 μm, and still more preferably from 20 μm to 30 μm. If the thickness of the contact layer 12 is too thin, a part of direct contact between the anode layer 13 and the metal support 11 may occur due to the influence of the surface roughness of the metal support 11, resulting in a partial diffusion reaction. If the thickness is high and too thick, the electrical resistance may increase.

According to one embodiment of the present invention, a solid electrolyte layer 14 may be stacked on top of the anode layer 13 . The solid electrolyte layer 14 prevents mixing of hydrogen and air and allows only oxygen ions to pass through. In addition, components of the solid electrolyte layer 14 may be rare earth-doped zirconia, rare earth-doped ceria, or perovskite-based oxide.

The average thickness of the solid electrolyte layer 14 ranges from 5 μm to 30 μm, more preferably from 10 μm to 20 μm. The performance of the solid oxide fuel cell cell increases because the internal resistance decreases as the thickness of the solid electrolyte layer 14 becomes thinner, and the effect of compensating for low ion conductivity can be obtained, but if it is too thin, the solid electrolyte layer ( If a cross-over phenomenon occurs where fuel gas and air directly meet through the local defect of 14), not only the electromotive force is reduced, but also a hot spot is generated around that part, resulting in cell performance deterioration. can be reduced to Therefore, the solid electrolyte layer 14 may require an appropriate thickness at a level where crossover does not occur.

Meanwhile, a cathode layer 16 may be stacked on the solid electrolyte layer 14 . The cathode layer 16 may produce oxygen ions by reducing air supplied from the outside. In addition, the components of the cathode layer 16 may include a perovskite-based oxide-containing conductor alone or a pore forming agent such as a sintered powder mixture of rare earth-doped ceria and graphite powder. The perovskite-based oxide and the rare earth-doped ceria may be as defined above.

Specifically, the perovskite-based oxide included in the cathode layer 16 is La _1-x Sr _x Co _y Fe _1-y O _3-δ (however, x = 0.2 to 0.5, y = 0.2 to 1 and δ = 0 to 0.3). In particular, the perovskite oxide mixed conductor contains one or more of La _0.6 Sr _0.4 Co _0.2 Fe _0.8 O _3-δ , GdCoO _3-δ and Re _x Sr _1-x CoO _3-δ (Re=La, Sm , Pr, 0.5<x<0.8 and δ=0∼0.3). Using these compounds can be useful as they have higher ionic conductivities than most perovskite-based oxides. In some cases, the mixture may include in the range of 20 to 50% by weight, in some cases in the range of 30 to 45% by weight, in some cases in the range of 35 to 45% by weight, or approximately 40% by weight rare earth-doped ceria as defined above. there is. This helps to improve the compatibility between the solid electrolyte layer 14 and the cathode layer 16 both in terms of chemical and aforementioned thermal expansion, and since these cerias have a high charge transport rate, including them is a solid electrolyte layer (14) and a good charge transport rate between the cathode layer (16) can be ensured.

More specifically, the cathode layer 16 may include a perovskite-based oxide such as LSM (La _0.8 Sr _0.2 MnO ₃ ) and Sc-doped ZrO ₂ (ScSZ). On the other hand, the LSM is used as a material for the cathode or as the solid electrolyte layer 14, among rare earth-doped ceria or perovskite-based oxides La _1-x A _x Ga _1-y B _y O ₃ (A = Sr, Ba; B = Mg, Ca; x = 0.05 to 0.3; y = 0.05 to 0.3) is excellent in high temperature and chemical stability, so additional configuration may not be required.

On the other hand, high-performance cathode materials such as LSCF ((La _0.6 Sr _0.4 ) (Co _0.2 Fe _0.8 ) O ₃ ) and BSCF (Br _0.5 Sr _0.5 Co _0.8 Fe _0.2 O _3-δ ) are used as the cathode layer 16 instead of LSM. Alternatively, when rare earth-doped zirconia is used as the solid electrolyte layer 14, a protective layer 15 may be additionally inserted between the solid electrolyte layer 14 and the cathode layer 16. In addition, the average thickness of the cathode layer 16 may be in the range of 10 to 50 μm.

The protective layer 15 is located between the solid electrolyte layer 14 and the cathode layer 16 to prevent the diffusion of the composition between the layers, thereby suppressing the generation of impurities, Ce _1-y Ln _y O _2-β (Ln = Gd, Sm, Nd or La, y = 0.1 to 0.3, β = 0 to 0.2). Here, the protective layer 15 is a solid electrolyte layer 14 made of Ce _1-x Ln _x O _2-δ (Ln = La, Gd, Sm, Nd or Y, x = 0.1 to 0.3, δ = 0 to 0.2) Compared to , the y may be greater than x, and the β may be greater than δ.

In addition, according to one embodiment of the present invention, a current collector 17 may be additionally stacked on top of the cathode layer 16 . The current collector 17 allows current to be collected from the cells in the stack. In this case, the current collector 17 may be any electrically conductive ceramic material, and may generally be a perovskite such as lanthanum strontium copper oxide (LSC).

Hereinafter, preferred experimental examples are presented to aid understanding of the present invention. However, the following experimental examples are only for helping understanding of the present invention, and the present invention is not limited by the following experimental examples.

<Production Examples>

Preparation Example 1: Ni-based metal support type solid oxide fuel cell

Preparation of metal support composed of Ni _1-x Fe _x (x = 0 ~ 1)

NiO (Kceracell, 99.9%, (d50) ∼ 0.7 μm) and Fe ₂ O ₃ (LTS Research laboratories, 99.9%) were mixed at a volume ratio of 5:5 to perform a ball mill process. Thereafter, the powder obtained by drying was produced into pellets of 1 g each (about 1 mm thick) using a mold having a diameter of 20 mm (pressing pressure: 50 MPa). The prepared pellets were subjected to pre-sintering at 900 °C for 2 hours.

Manufacture of the contacting layer

For the preparation of the contact layer, a slurry was prepared first. The slurry is a metal support component NiO (Kceracell, 99.9%) and an anode component 8YSZ ((Y ₂ O ₃ ) _0.08 (ZrO ₂ ) _0.92 , Kceracell, 99.9%, (d50) ~ 0.2 μm) or ScSZ-6 ( 6 mol% Sc ₂ O ₃ ) was prepared through ball milling after adding corn starch to raw material powder mixed in a volume ratio of 7:3. The prepared slurry was drop coated on pre-sintered pellets and then dried in an oven (30 °C).

Manufacturing of anode made of Ni-ScSZ (Ce, Gd)

For the manufacture of the anode layer, first, a slurry was prepared. The slurry was a raw material powder NiO (Kceracell, 99.9%), 10Sc _0.5 Ce _0.5 GdSZ [(Sc ₂ O ₃ ) _0.1 (CeO ₂ ) _0.005 (Gd ₂ O ₃ ) _0.005 (ZrO ₂ ) _0.89 mixed in a volume ratio of 5.5:4.5 , Kceracell, 99.9%, (d50) ∼ 0.2 ㎛] and corn starch were mixed and manufactured through ball milling (150 rpm, 24 hours). 230 μl of the prepared slurry was drop-coated on the pellets formed up to the contact layer, and then dried in an oven (30° C.).

Preparation of solid electrolyte layer composed of ScSZ (Ce, Gd)

For the preparation of the solid electrolyte layer, a slurry was prepared first. The slurry is a mixture of 10Sc _0.5 Ce _0.5 GdSZ ((Sc ₂ O ₃ ) _0.1 (CeO ₂ ) _0.005 (Gd ₂ O ₃ ) _0.005 (ZrO ₂ ) _0.89, Kceracell, 99.9%, (d50) ∼ 0.2 μm) and ethanol. and prepared through ball milling (150 rpm, 24 hours). 120 μl of the prepared slurry was drop coated on the pellets coated up to the anode layer, and then dried in an oven (30° C.). After drying, co-sintering was performed at 1350 °C.

Manufacture of a cathode layer containing LSM and ScSZ (Ce, Gd) and a cell containing the same

In the case of the cathode layer, it was formed through a screen printing technique on a dense solid electrolyte layer. Cathode powder LSM (La _0.8 Sr _0.2 MnO ₃ ), Kceracell, 99.9%, (d50) ∼ 0.5 μm), and ScSZ were mixed. For screen printing, a 7.5 mm diameter circle was formed in the center of the solid electrolyte layer using a 30 μm thick mesh substrate and the cathode mixture powder. Thereafter, heat treatment was performed in air at 1200° C. for 2 hours to manufacture a cell.

Preparation Example 2: STS-based metal support type solid oxide fuel cell

Manufacture of STS-based metal supports

STS434L (Fe/16.5Cr/1Mo/0.2Ni/0.1Mn/0.0055S/0.017C/0.025P/0.8Si, Hoganas) powder, ethanol (SAMCHUN, purity 99.9%) and binder (PVB-76, SAMCHUN, purity 99.9%) was mixed and ball milled to prepare a slurry. A tape molded body in the form of a thick film was produced by using the prepared slurry through a tape casting (using a Tape casting machine, STC-14C) process.

Manufacture of the contacting layer

Crofer22 (Fe/22Cr/0.8Ti/0.5Mn/0.002S/0.005C/0.016P/0.006La, thyssenkrupp), 8YSZ((Y ₂ O ₃ ) _0.08 (ZrO ₂ ) _0.92 , Kceracell, 0.22um, 50 wt% ) Or 20 g of ScSZ-6 (6 mol% Sc ₂ O ₃ ), ethanol (SAMCHUN, purity 99.9%) and a binder (PVB-76, SAMCHUN, 99%) were mixed and then ball milled to prepare a slurry. A tape molded body in the form of a thick film was produced by using the prepared slurry through a tape casting (using a Tape casting machine, STC-14C) process.

Preparation of anode (cathode) layer containing Ni, ScSZ (Ce, Gd) and LST37

NiO (Kceracell), 10ScSZ (10% Sc ₂ O ₃ , ZrO ₂ doped with 0.5% CeO ₂ and 0.5% Gd ₂ O ₃ , Kceracell), LST37 (La _0.7 Sr _0.3 TiO ₃ , Kceracell), ethanol (SAMCHUN, Purity 99.9%) and a binder (PVB-76, SAMCHUN, 99%) were mixed and then ball milled to prepare a slurry. A tape molded body in the form of a thick film was produced by using the prepared slurry through a tape casting (using a Tape casting machine, STC-14C) process.

Preparation of ScSZ (Ce, Gd) solid electrolyte layer

10ScSZ (ZrO ₂ , Kceracell doped with 10% Sc ₂ O ₃ , 0.5% CeO ₂ and 0.5% Gd ₂ O ₃ ), ethanol (SAMCHUN, purity 99.9%) and binder (PVB-76, SAMCHUN, 99%) After mixing, a slurry was prepared by ball milling. A tape molded body in the form of a thick film was manufactured using the prepared slurry by using a tape-casting machine (STC-14C) process.

Lamination and co-sinitering processes

After stacking the thick film-type tape molded bodies (metal support, contact layer, fuel electrode layer, and solid electrolyte layer) obtained through the tape casting process, a hot pressing process (applying a pressure of about 20 MPa) was performed. After that, the obtained laminate was sintered (1350 ° C., maintained for 4 hours).

Manufacturing of air cathode (anode) layer containing LSM and ScSZ (Ce, Gd) and cell including the same

To prepare the cathode layer, cathode layer powder was prepared by mixing Sr-doped LaMnO ₃ (LSM) and 10 ScSZ (10 mol% Sc ₂ O ₃ -doped ZrO ₂ ) in a volume ratio of 7:3. A cathode layer was formed by screen-printing the cathode layer powder on the solid electrolyte layer of the obtained sintered body using a screen printing plate having a thickness of 30 μm. Thereafter, heat treatment was performed at 1200° C. to obtain a fuel cell.

Comparative Example 1: Ni-based metal support type solid oxide fuel cell without contact layer

The remaining layers except for the contact layer were prepared in the same manner as in Preparation Example 1.

Comparative Example 2: STS-based metal-supported solid oxide fuel cell without contact layer

The remaining layers except for the contact layer were prepared in the same manner as in Preparation Example 2.

2 is a cross-sectional view comparing microstructures of Ni-based metal support type solid oxide fuel cells before and after reduction. 2(a) and (b) show the microstructure before reduction, and FIGS. 2(c) and (d) show the microstructure after reduction. 2(a) and (c) show a fuel cell including a contact layer, and FIG. 2(b) and (d) show a fuel cell not including a contact layer.

As a result of comparing the microstructures before and after reduction, it can be confirmed that the microstructures of the metal support and the anode layer in FIGS. 2 (b) and (d) using a fuel cell without a contact layer have a large difference in density and particle size. can Due to the large difference in density and particle size, not only does a large deformation occur between the layers constituting the fuel cell, but the compatibility between the layers is poor and is easily destroyed during thermal gradient within the fuel cell. can In addition, when the porosity from the metal support to the anode layer is rapidly changed, a large difference in gas flow or distribution may be caused.

Meanwhile, referring to FIGS. 2(a) and (c), it can be seen that the difference in microstructure between the metal support and the anode layer is alleviated by inserting the contact layer into the fuel cell. As the difference in microstructure in the fuel cell is alleviated, deformation between layers is reduced, thermal fracture is reduced, and compatibility is improved, resulting in increased resistance to internal and external stress. can In addition, by reducing a sudden change in porosity from the metal support to the anode layer, gas flow or distribution and current flow can be smoothed. Therefore, when the contact layer is included in the fuel cell, it can be confirmed that the change in the microstructure before and after reduction is remarkably reduced.

3 is a cross-sectional view comparing microstructures of STS-based metal-supported solid oxide fuel cells. FIG. 3(a) shows a fuel cell including a contact layer, and FIG. 3(b) shows a fuel cell not including a contact layer. Comparing FIGS. 3(a) and (b), in the case of FIG. 3(a) including the contact layer in the fuel cell, it can be confirmed that the difference in microstructure between the metal support and the anode layer is alleviated.

< Experiments; Examples >

Experimental Example 1: Density test

The ImageJ program was used to measure the density of each layer constituting the fuel cell. Through the ImageJ program, first, the SEM image of each layer was scanned. At this time, the sample appears bright and the pores appear dark, and the density was measured through this ratio. The density of each layer was measured before and after reduction of the fuel cell according to an embodiment of the present invention and depending on whether or not there was a contact layer, and these are shown in Table 1 below.

division Density (before reduction) Density (after reduction) with contact layer no contact layer with contact layer no contact layer Air Cathode (Anode) Layer ~75% ~75% ~75% ~75% solid electrolyte layer ~99% ~99% ~99% ~99% Anode (cathode) layer ~92% ~92% ~75% ~75% contact layer ~82% - ~70% - metal support ~67% ~66% ~57% ~57%

As a result of observing the density of each layer in the cell constituting the fuel cell before and after reduction of the fuel cell, as shown in Table 1, the density of the contact layer before reduction was higher than that of the metal support and smaller than that of the anode layer. . In addition, it can be seen that the density of the contact layer is formed between the metal support and the anode layer density even after reduction. Therefore, it can be confirmed that the microstructure difference between the metal support and the anode layer is alleviated by the addition of the contact layer.

Experimental Example 2: Measurement of Thermal Expansion Coefficient

In order to measure the thermal expansion coefficient of each layer constituting the fuel cell, it was measured using a thermomechanical analyzer (TA Instrument, Q400) under measurement conditions of a load of 0.1 N and N ₂ flow of 100 ml/min. The thermal expansion coefficients of each layer constituting the fuel cell cells manufactured according to Preparation Example 1 and Comparative Example 1 are listed in Table 2 below.

Preparation Example 1 Comparative Example 1 solid electrolyte layer 10 to 11 ppm/℃ 10 to 11 ppm/℃ anode layer 12 to 14.5 ppm/℃ 12 to 14.5 ppm/℃ contact layer 13.5 to 16.5 ppm/℃ - metal support 15 to 18 ppm/℃ 15 to 18 ppm/℃

Referring to Table 2, the thermal expansion coefficient of the contact layer inserted in Preparation Example 1 was found to be 13.5 ppm/°C to 16.5 ppm/°C, and the value existed between the thermal expansion coefficients of the metal support and the anode layer, thereby increasing the thermal expansion coefficient. It can have a gradient. In the case of Preparation Example 1 having the thermal expansion coefficient gradient, compared to Comparative Example 1, thermal fracture is reduced and compatibility is improved, resulting in increased resistance to internal and external stress. It is possible to suppress interlayer separation of the fuel cell due to

Experimental Example 3: Stress test

To evaluate the lifespan of a fuel cell cell, stress due to cell destruction was measured. The stress may appear through microscopic pores of the contact surface between the cell layers or discontinuous portions of the structure.

4 is a radius of curvature formed when a contact layer (Manufacturing Example 1) or an anode layer (Comparative Example 1) is respectively laminated on a metal support. Comparing FIG. 4(a) with FIG. 4(b), in the case of FIG. 4(a) in which the contact layer is stacked, the particle size is relatively larger than in FIG. 4(b) in which the anode layer is stacked, so that the contact layer The radius of curvature appearing at the interface between the metal support and the metal support may also appear wide. Stress applied to the fuel cell cells of Preparation Example 1 and Comparative Example 1 was calculated using the radius of curvature and Equation 1 below, which is shown in Table 3 below.

[Equation 1]

At this time, σ _m is the maximum stress that can withstand right before failure, and σ ₀ is is the nominal applied tensile stress, a is the surface/interior crack length, ρ _t is is the radius of curvature of the crack portion.

Preparation Example 1 Comparative Example 1 σ _m (maximum stress) 28σ ₀ (a) ^1/2 63σ ₀ (a) ^1/2 σ ₀ (tensile stress) σ ₀ σ ₀ a (surface crack length) a a ρ _t (radius of curvature) 50 10 particle size ~3 ㎛ ~1 ㎛

Referring to Table 3, in Preparation Example 1 and Comparative Example 1 σ _m (maximum stress) values were 28σ ₀ (a) ^1/2 and 63σ ₀ (a) ^1/2 , respectively, and in the case of Preparation Example 1 with a contact layer, compared to Comparative Example 1 without a contact layer It can be seen that the σ _m (maximum stress) value decreases to less than 1/2. Therefore, when the contact layer is present, the stress applied to the fuel cell is significantly reduced, suppressing separation between layers in the fuel cell, and further increasing the lifespan of the fuel cell and improving thermal cycle characteristics.

In the above, the present invention has been described in detail with preferred embodiments, but the present invention is not limited to the above embodiments, and various modifications and variations are made by those skilled in the art within the technical spirit and scope of the present invention. Change is possible.

Claims (16)

metal support; a contact layer stacked on top of the metal support and serving as a buffer in terms of microstructure while passing gas and electricity; an anode layer stacked on top of the contact layer and producing water and electrons by combining ionized oxygen ions and injected hydrogen; a solid electrolyte layer stacked on top of the anode layer to prevent mixing of hydrogen and air and to allow oxygen ions to pass therethrough; and A metal support type solid oxide fuel cell comprising a cathode layer stacked on top of the solid electrolyte layer and producing oxygen ions by reducing injected air. According to claim 1, A metal support type solid oxide fuel cell comprising a protective layer between the electrolyte layer and the cathode layer. According to claim 2, The protective layer is a metal support type solid oxide fuel cell containing Ce _1-y Ln _y O _2-β (Ln = Gd, Sm, Nd or La, y = 0.1 ~ 0.3, β = 0 ~ 0.2). According to claim 1, A metal support type solid oxide fuel cell comprising a current collector stacked on an upper portion of the cathode layer. According to claim 1, The metal support is a metal support type solid oxide fuel cell of any one of Ni metal, Ni-Fe alloy and STS (Stainless Steel) system. According to claim 1, The metal support type solid oxide fuel cell wherein the anode layer is any one of a composite of NiO and rare earth-doped zirconia or a composite of NiO and rare earth-doped ceria. According to claim 6, The anode layer further includes at least one of perovskite oxide and CeO ₂ , The perovskite-based oxide is A' _x B' _y O ₃ (provided that 0≤x≤1, 0≤y≤1, and A'= at least one of La, Sr, Ba, Pr, and Sm; B'= At least one of Ti, Y, Sc, Cr, V, Mn, Co, Fe, Ni, Mo, Nb, Al, Mg, and Ca) A metal support type solid oxide fuel cell. According to claim 1, A composition of the cathode layer includes a perovskite-based oxide, The perovskite-based oxide is A' _x B' _y O ₃ (provided that 0≤x≤1, 0≤y≤1, and A'= at least one of La, Sr, Ba, Pr, and Sm; B'= At least one of Ti, Y, Sc, Cr, V, Mn, Co, Fe, Ni, Mo, Nb, Al, Mg, and Ca) A metal support type solid oxide fuel cell. According to claim 8, The metal support type solid oxide fuel cell further comprising at least one of a sintered powder mixture of rare earth-doped ceria or a pore former as a composition of the cathode layer. According to claim 1, wherein the electrolyte layer is any one of a rare earth-doped zirconia-based oxide, a rare-earth-doped ceria-based oxide, and a perovskite-based oxide. According to claim 10, The perovskite-based oxide is La _1-x A _x Ga _1-y B _y O ₃ (A = Sr, Ba; B = Mg, Ca) metal support type solid oxide fuel cell. According to any one of claims 1 to 6, The metal support type solid oxide fuel cell in which the contact layer is a mixture of components of the metal support and components of the fuel electrode layer. According to any one of claims 1 to 6, A metal support type solid oxide fuel cell having a composition ratio of the metal support component of the contact layer and the fuel electrode layer component of 7:3 to 3:7. According to claim 12, The metal support type solid oxide fuel cell, characterized in that the particle size of the contact layer is 0.3 ㎛ to 30 ㎛. According to claim 12, The metal support type solid oxide fuel cell, characterized in that the thickness of the contact layer is 5 ㎛ to 50 ㎛. According to claim 12, The metal support type solid oxide fuel cell, characterized in that the thermal expansion coefficient of the contact layer is 10 (ppm / ℃) to 20 (ppm / ℃).

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