Electrolyte sheet for electrochemical cell, and electrochemical cell

Abstract

An electrolyte sheet (11) comprises a first main surface (S1), a second main surface (S2), a side surface (S3) continuous with the first main surface (S1) and the second main surface (S2), and a protrusion (14) formed on the outer edge of the first main surface (S1).

Description

Electrolyte sheets and electrochemical cells for electrochemical cells

[0001] This invention relates to an electrolyte sheet for an electrochemical cell and an electrochemical cell.

[0002] Conventionally, electrochemical cells (such as electrolytic cells and fuel cell cells) comprising a hydrogen electrode, an oxygen electrode, and an electrolyte sheet placed between the hydrogen and oxygen electrodes are known.

[0003] The electrolyte sheet is joined to a separator that separates the hydrogen electrode space from the oxygen electrode space via a sealing portion (see, for example, Patent Document 1).

[0004] Japanese Patent Publication No. 2011-228290

[0005] If the bonding strength between the electrolyte sheet and the seal deteriorates, gas leakage may occur between the hydrogen electrode space and the oxygen electrode space.

[0006] The object of the present invention is to provide an electrolyte sheet for an electrochemical cell and an electrochemical cell capable of improving bonding with the sealing portion.

[0007] An electrolyte sheet for an electrochemical cell according to the first aspect of the present invention comprises a first main surface, a second main surface, a side surface connected to the first main surface and the second main surface, and a protrusion formed on the outer edge of the first main surface.

[0008] The electrolyte sheet for an electrochemical cell according to the second aspect of the present invention relates to the first aspect, wherein the protrusion extends along the outer edge of the first main surface.

[0009] The electrolyte sheet for an electrochemical cell according to the third aspect of the present invention relates to the first or second aspect described above, and has an average thickness of 45 μm or less.

[0010] An electrochemical cell according to a fourth aspect of the present invention comprises an electrolyte sheet for an electrochemical cell according to any of the first to third aspects described above; a cell body having a first electrode disposed on the first main surface and a second electrode disposed on the second main surface; a separator; and a sealing portion disposed between the electrolyte sheet for the electrochemical cell and the separator. The sealing portion is bonded to the second main surface and the side surface of the electrolyte sheet for the electrochemical cell.

[0011] An electrochemical cell according to a fifth aspect of the present invention comprises an electrolyte sheet for an electrochemical cell according to any of the first to third aspects described above; a cell body having a first electrode disposed on the first main surface and a second electrode disposed on the second main surface; a separator; and a sealing portion disposed between the electrolyte sheet for the electrochemical cell and the separator. The sealing portion is bonded to the first main surface and the side surface of the electrolyte sheet for the electrochemical cell. The protrusions bite into the sealing portion.

[0012] According to the present invention, it is possible to provide an electrolyte sheet for an electrochemical cell and an electrochemical cell that can improve bonding with the sealing portion.

[0013] Figure 1 is a plan view of an electrochemical cell according to an embodiment. Figure 2 is a cross-sectional view of the electrochemical cell according to an embodiment. Figure 3 is a partially enlarged view of Figure 2. Figure 4 is a cross-sectional view of an electrochemical cell according to Modification 1. Figure 5 is a cross-sectional view of an electrolyte sheet according to Modification 3.

[0014] (Electrochemical Cell 1) The electrochemical cell according to the present invention is a general term for an element in which a pair of electrodes are arranged so that an electromotive force is generated from an overall oxidation-reduction reaction in order to convert electrical energy into chemical energy, and an element for converting chemical energy into electrical energy. Electrochemical cells include solid oxide electrolytic cells (SOECs) and solid oxide fuel cells (SOFCs) that use ions or protons as carriers.

[0015] Figure 1 is a plan view showing the configuration of an electrochemical cell 1 according to an embodiment. Figure 2 is a cross-sectional view taken along line A-A in Figure 1. Figure 2 shows a cross-section of an electrolyte sheet 11 that passes through the geometric center CP of the first main surface S1 (described later) and is perpendicular to the first main surface S1.

[0016] In this embodiment, the electrochemical cell 1 is formed in the shape of a rectangular plate extending in the X-axis direction and the Y-axis direction. The X-axis direction is the short-axis direction of the electrochemical cell 1, and the Y-axis direction is the long-axis direction of the electrochemical cell 1. However, the planar shape of the electrochemical cell 1 is not particularly limited and may be a polygon other than a rectangle, an ellipse, a circle, etc.

[0017] As shown in Figures 1 and 2, the electrochemical cell 1 comprises a cell body 10, a separator 20, and a sealing portion 30.

[0018] [Cell body 10] The cell body 10 has an electrolyte sheet for electrochemical cells (hereinafter abbreviated as "electrolyte sheet") 11, an oxygen electrode 12, and a hydrogen electrode 13.

[0019] The electrolyte sheet 11 is formed in a dense, thin plate shape. The electrolyte sheet 11 has a first main surface S1, a second main surface S2, and a side surface S3. As shown in Figure 2, the first main surface S1 and the second main surface S2 each extend along the X-axis direction. The first main surface S1 and the second main surface S2 each may be curved or bent in whole or in part. The first main surface S1 is provided on the opposite side of the second main surface S2. The side surface S3 refers to the area of ​​the surface of the electrolyte sheet 11 that is visible in a side view of the electrolyte sheet 11. The side surface S3 is continuous with the first main surface S1 and the second main surface S2. The side surface S3 is formed in an annular shape.

[0020] The electrolyte sheet 11 can be made of at least one ceramic material selected from zirconia oxide, LaGaO3 oxide, and ceria oxide.

[0021] Examples of zirconia-based oxides include zirconia in which one or more oxides selected from alkaline earth metal oxides such as MgO, CaO, SrO, and BaO, rare earth element oxides such as Sc2O3, Y2O3, La2O3, CeO2, Pr2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, Dy2O3, Ho2O3, Er2O3, and Yb2O3 are solid-solution zirconia.

[0022] Examples of LaGaO3-based oxides include composite oxides having a perovskite crystal structure in which some of the La and Ga are substituted with Sr, Y, Mg, etc. Specifically, examples of LaGaO3-based oxides include La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 La like O3 1-x Sr x Ga 1-y Mgy O₃, La 1-x Sr x Ga 1-y Mg y Co₂O₃, La 1-x Sr x Ga 1-y Fe y O₃, La 1-x Sr x Ga 1-y Ni y Examples include O₃ and the like.

[0023] Examples of the ceria-based oxide include ceria doped with one or more oxides selected from CaO, SrO, BaO, Ti₂O₃, Y₂O₃, La₂O₃, Pr₂O₃, Nd₂O₃, Sm₂O₃, Eu₂O₃, Gd₂O₃, Tb₂O₃, Dy₂O₃, Er₂O₃, Tm₂O₃, Yb₂O₃, PbO, WO₃, MoO₃, V₂O₅, Ta₂O₅, Nb₂O₅, and the like.

[0024] The average thickness of the electrolyte sheet 11 is preferably 45 μm or less. Thereby, the area resistance of the electrochemical cell 1 can be reduced. The average thickness of the electrolyte sheet 11 is the arithmetic mean value when the thickness of the electrolyte sheet 11 is measured at five randomly selected locations. The thickness of the electrolyte sheet 11 shall be measured using a micrometer.

[0025] The porosity of the electrolyte sheet 11 is not particularly limited, but can be, for example, 0.1% or more and 3% or less.

[0026] The oxygen electrode 12 is an example of the "first electrode" according to the present invention. The oxygen electrode 12 is disposed on the first main surface S1 of the electrolyte sheet 11.

[0027] The oxygen electrode 12 is a porous body having ion conductivity and conductivity. The oxygen electrode 12 is, for example, (La, Sr)(Co, Fe)O ３ , (La, Sr)FeO ３ , La(Ni, Fe)O ３ , (La, Sr)CoO ３ , and (Sm, Sr)CoO ３It can be composed of one or more oxides selected from the like. The oxygen electrode 12 may contain an ion conductive material (such as GDC).

[0028] The porosity of the oxygen electrode 12 is not particularly limited, but can be, for example, 20% or more and 60% or less. The thickness of the oxygen electrode 12 is not particularly limited, but can be, for example, 1 μm or more and 50 μm or less.

[0029] A reaction prevention layer may be inserted between the electrolyte sheet 11 and the oxygen electrode 12 to suppress the formation of a layer with high electrical resistance due to the reaction of the constituent elements of the electrolyte sheet 11 with the constituent elements of the oxygen electrode 12. The reaction prevention layer can be composed of an ion conductive material (such as GDC, SDC).

[0030] The hydrogen electrode 13 is an example of the "second electrode" according to the present invention. The hydrogen electrode 13 is disposed on the second main surface S2 of the electrolyte sheet 11.

[0031] The hydrogen electrode 13 is a porous body having gas diffusibility and conductivity. The hydrogen electrode 13 contains a conductive material and an ion conductive material. As the conductive material, metal materials such as Ni (nickel), Fe (iron), and conductive ceramic materials can be used. As the ion conductive material, one or more selected from YSZ, CSZ, ScSZ, GDC, SDC, (La, Sr)(Cr, Mn)O ３ 、(La, Sr)TiO ３ 、Sr ２ (Fe, Mo) ２ O ６ 、(La, Sr)VO ３ 、(La, Sr)FeO ３ 、LDC, LSGM, etc. can be used.

[0032] The porosity of the hydrogen electrode 13 is not particularly limited, but can be, for example, 10% or more and 40% or less. The thickness of the hydrogen electrode 13 is not particularly limited, but can be, for example, 1 μm or more and 50 μm or less.

[0033] [Separator 20] The separator 20 is a frame-shaped member also called an interconnector. The separator 20 is made of a dense metal or ceramic material. The separator 20 is formed in an annular shape. The separator 20 is positioned along the outer edge of the cell body 10. The separator 20 is joined to the outer edge of the electrolyte sheet 11 via the seal portion 30. This separates the oxygen electrode side space T1 and the hydrogen electrode side space T2.

[0034] [Seal portion 30] The seal portion 30 seals the gap between the cell body portion 10 and the separator 20. The seal portion 30 joins the electrolyte sheet 11 and the separator 20. The seal portion 30 is formed in an annular shape. The seal portion 30 can be made of, for example, crystallized glass. As for the crystallized glass, for example, SiO ２ -B ２ O ３ system, SiO ２ -CaO system, MgO-B ２ O ３ System, or SiO ２ -MgO-based crystallized glass can be used. Crystallized glass is glass in which the ratio of the volume occupied by the crystalline phase to the total volume (degree of crystallinity) is 60% or more, and the ratio of the volume occupied by the amorphous phase and impurities to the total volume is less than 40%.

[0035] (Detailed configuration of electrolyte sheet 11) Figure 3 is a partially enlarged view of Figure 2. As shown in Figure 3, the electrolyte sheet 11 has a first main surface S1, a second main surface S2, and a side surface S3.

[0036] The electrolyte sheet 11 has a protrusion 14 formed on the outer edge of the first main surface S1. The protrusion 14 is a portion of the outer edge of the electrolyte sheet 11 that is partially thicker. By providing the protrusion 14, it is possible to suppress the seal portion 30 from adhering to the first main surface S1 beyond the side surface S3. Therefore, the area of ​​the side surface S3 covered by the seal portion 30 can be widened. Thus, the bonding between the electrolyte sheet 11 and the seal portion 30 can be improved. It is preferable that the protrusion 14 extends along the outer edge of the first main surface S1.

[0037] The height of the protrusion 14 in the Z-axis direction is not particularly limited, but can be between 5 μm and 10 μm. The height of the protrusion 14 is the distance between the first main surface S1 and the vertex of the protrusion 14 in the Z-axis direction.

[0038] The width of the protrusion 14 in the X-axis direction or the Y-axis direction is not particularly limited, but can be 5 μm or more and 50 μm or less. The width of the protrusion 14 is the distance between the end of the first main surface S1 and the vertex of the protrusion 14 in the X-axis direction or the Y-axis direction.

[0039] Side surface S3 includes a first side surface S31 and a second side surface S32. The first side surface S31 is connected to the first main surface S1 and the second side surface S32, respectively. The first side surface S31 is inclined with respect to the first main surface S1 and the second side surface S32, respectively. The boundary M1 between the first side surface S31 and the first main surface S1 may be bent or formed in an R shape. The boundary M2 between the first side surface S31 and the second side surface S32 may be bent or formed in an R shape.

[0040] The first side surface S31 may be planar or curved. If the first side surface S31 is curved, the contour of the first side surface S31 may be convex toward the outside of the electrolyte sheet 11, but it is preferable that it be convex toward the inside of the electrolyte sheet 11.

[0041] The second side surface S32 is formed along the Z-axis direction, which is perpendicular to the X-axis and Y-axis directions. The second side surface S32 is formed in a planar shape. The second side surface S32 is connected to the second main surface S2 and the first side surface S31, respectively. The boundary M3 between the second side surface S32 and the second main surface S2 may be bent or formed in an R-shape.

[0042] At boundary M2, the interior angle formed by the first surface S31 and the second surface S32 is not particularly limited, but can be, for example, 120 degrees or more and 160 degrees or less. The height of the first surface S31 in the Z-axis direction is not particularly limited, but can be 10 μm or more and 20 μm or less. The height of the second surface S32 in the Z-axis direction is not particularly limited, but can be 5 μm or more and 30 μm or less.

[0043] It is preferable that the surface roughness Rz of the first side surface S31 is greater than the surface roughness Rz of the second side surface S32. This makes it possible to further increase the bonding force of the seal portion 30 to the first side surface S31.

[0044] The surface roughness Rz is a parameter based on the JIS B 0601:2013 standard. The surface roughness Rz is measured using a white light interferometer-equipped laser microscope (VK-X3000) manufactured by Keyence Corporation. Specifically, the surface roughness Rz of the first side surface S31 is calculated by acquiring roughness curves of the first side surface S31 at 30 locations in a direction perpendicular to the boundary M2 and taking the arithmetic mean of the surface roughness of each roughness curve. Similarly, the surface roughness Rz of the second side surface S32 is calculated by acquiring roughness curves of the second side surface S32 at 30 locations in a direction perpendicular to the boundary M2 and taking the arithmetic mean of the surface roughness Rz of each roughness curve. The roughness curves are acquired at a total of 30 locations, with 5 locations set at 25 μm intervals in 6 random fields of view.

[0045] The surface roughness Rz of the first side surface S31 is not particularly limited, but can be between 1 μm and 5 μm. The surface roughness Rz of the second side surface S32 is not particularly limited, but can be between 0.1 μm and 1.5 μm.

[0046] The sealing portion 30 is joined to the second main surface S2, the second side surface S32, and the first side surface S31. In other words, the sealing portion 30 sandwiches the electrolyte sheet 11 from both sides in the Z-axis direction.

[0047] In Figure 3, the sealing portion 30 is filled in the gap between the electrolyte sheet 11 and the separator 20. However, the sealing portion 30 may be placed in only a part of the gap between the electrolyte sheet 11 and the separator 20, or the sealing portion 30 may protrude inward (to the left in Figure 3) from the gap between the electrolyte sheet 11 and the separator 20.

[0048] (Modifications of Embodiments) Although embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications are possible without departing from the spirit of the invention.

[0049] (Modification 1) In the above embodiment, the seal portion 30 is joined to the second main surface S2, the second side surface S32, and the first side surface S31, but it is not limited to this. As shown in Figure 4, the seal portion 30 may be joined to the first main surface S1 and the first side surface S31. In this case, the bonding between the electrolyte sheet 11 and the seal portion 30 can be improved by the anchoring effect obtained by the protrusion 14 biting into the seal portion 30.

[0050] (Modification 2) In the above embodiment, the second side surface S32 is formed along the Z-axis direction, but is not limited to this. The second side surface S32 may be inclined with respect to the Z-axis direction. Also, the second side surface S32 may be curved or bent in whole or in part.

[0051] (Modification 3) In the above embodiment, the side surface S3 of the electrolyte sheet 11 has a first side surface S31 and a second side surface S32, but as shown in Figure 5, the side surface S3 may be planar overall.

[0052] (Modification 4) In the above embodiment, the oxygen electrode 12 is arranged on the first main surface S1 of the electrolyte sheet 11 and the hydrogen electrode 13 is arranged on the second main surface S2 of the electrolyte sheet 11, but the embodiment is not limited to this. The hydrogen electrode 13 may be arranged on the first main surface S1 of the electrolyte sheet 11 and the oxygen electrode 12 may be arranged on the second main surface S2 of the electrolyte sheet 11. In this case, the hydrogen electrode 13 is an example of the "first electrode" according to the present invention, and the oxygen electrode 12 is an example of the "second electrode" according to the present invention.

[0053] (Modification 5) In the above embodiment, the structure of the electrolyte sheet 11 was described with reference to one cross-section of the electrolyte sheet 11. However, it is preferable that the above structure be observed in the entire cross-section of the electrolyte sheet 11 passing through the geometric center CP of the first main surface S1 and perpendicular to the first main surface S1. However, even if the above structure is observed in only one cross-section of the electrolyte sheet 11, the above effect can be achieved in that region.

[0054] 1 Electrochemical cell 10 Cell body 11 Electrolyte sheet for electrochemical cell S1 First main surface S2 Second main surface S3 Side surface S31 First side surface S32 Second side surface 14 Protrusion 12 Oxygen electrode 13 Hydrogen electrode 20 Separator 30 Seal portion T1 Space on oxygen electrode side T2 Space on hydrogen electrode side

Claims

1. An electrolyte sheet for an electrochemical cell comprising: a first main surface; a second main surface; a side surface connected to the first main surface and the second main surface; and a protrusion formed on the outer edge of the first main surface.

2. The electrochemical cell electrolyte sheet according to claim 1, wherein the protrusion extends along the outer edge of the first main surface.

3. An electrolyte sheet for an electrochemical cell according to claim 1 or 2, wherein the average thickness is 45 μm or less.

4. An electrochemical cell comprising: an electrolyte sheet for an electrochemical cell as described in claim 1; a cell body having a first electrode disposed on the first main surface and a second electrode disposed on the second main surface; a separator; and a sealing portion disposed between the electrolyte sheet for an electrochemical cell and the separator, wherein the sealing portion is bonded to the second main surface and the side surface of the electrolyte sheet for an electrochemical cell.

5. An electrochemical cell comprising: an electrolyte sheet for an electrochemical cell as described in claim 1; a cell body having a first electrode disposed on the first main surface and a second electrode disposed on the second main surface; a separator; and a sealing portion disposed between the electrolyte sheet for an electrochemical cell and the separator, wherein the sealing portion is bonded to the first main surface and the side surface of the electrolyte sheet for an electrochemical cell, and the protrusions bite into the sealing portion.

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