Electrolyte sheet for 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 plurality of recessed grooves (15) formed in the side surface (S3) and extending along a direction perpendicular to a boundary (M1) between the first main surface (S1) and the side surface (S3).

Description

Electrolyte sheet for electrochemical cells

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

[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 electrode and the oxygen electrode are known (see, for example, Patent Document 1).

[0003] Japanese Patent Publication No. 2011-228290

[0004] If the electrolyte sheet deforms or external stress is applied to it, damage may occur to the sides of the electrolyte sheet.

[0005] The object of the present invention is to provide an electrolyte sheet for electrochemical cells that can suppress damage to the sides.

[0006] 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 plurality of grooves formed on the side surface and extending in a direction perpendicular to the boundary between the first main surface and the side surface.

[0007] An electrolyte sheet for an electrochemical cell according to a second aspect of the present invention relates to the first aspect, wherein the aspect has a first aspect connected to the first main surface and a second aspect connected to the second main surface and the first aspect.

[0008] An electrolyte sheet for an electrochemical cell according to a third aspect of the present invention relates to the second aspect, wherein the first aspect includes, in a side view, a first region on the first main surface side from the center in the height direction of the first aspect, and in a side view, a second region on the second aspect side from the center in the height direction of the first aspect. The plurality of grooves include first grooves formed in the first region and second grooves formed in the second region. The number of first grooves is greater than the number of second grooves.

[0009] The electrolyte sheet for an electrochemical cell according to the fourth aspect of the present invention relates to the third aspect, wherein the plurality of grooves include third grooves formed on the second aspect, and the number of first grooves is greater than the number of third grooves.

[0010] The electrolyte sheet for an electrochemical cell according to the fifth aspect of the present invention relates to any of the first to fourth aspects, and has a protrusion formed on the outer edge of the first main surface, and at least a portion of the plurality of grooves is formed on the protrusion.

[0011] The electrolyte sheet for an electrochemical cell according to the sixth aspect of the present invention relates to any of the first to fifth aspects described above, and has an average thickness of 45 μm or less.

[0012] According to the present invention, it is possible to provide an electrolyte sheet for electrochemical cells that can suppress damage to the sides.

[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 side view plan as seen from the X-axis direction. Figure 5 is a cross-sectional view of an electrochemical cell according to Modification 1. Figure 6 is a cross-sectional view of an electrochemical cell according to Modification 2. Figure 7 is a cross-sectional view of an electrolyte sheet according to Modification 4.

[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, etc.

[0024] The average thickness of the electrolyte sheet 11 is preferably 45 μm or less. This can reduce the area resistance of the electrochemical cell 1. 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 Rz 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] Here, Figure 4 is a plan view of the side view S3 as seen from the X-axis direction. The seal portion 30 is not shown in Figure 4.

[0049] As shown in Figure 4, the electrolyte sheet 11 has a plurality of grooves 15 formed on its side surface S3. Each groove 15 extends along a direction perpendicular to the boundary M1 between the first main surface S1 and the side surface S3 (specifically, the first side surface S31). This provides flexibility to the electrolyte sheet 11 in the direction along the boundary M1, thereby suppressing damage to the side surface S3 of the electrolyte sheet 11 even if the electrolyte sheet 11 is deformed or subjected to external stress. This effect can be obtained not only after the electrolyte sheet 11 is incorporated into the electrochemical cell 1, but also in the electrolyte sheet 11 as a standalone unit.

[0050] Furthermore, the concept that the groove 15 extends in a direction perpendicular to the boundary M1 includes not only the case where the straight line connecting the two furthest points on the contour line of the groove 15 in a plan view is parallel to the direction perpendicular to the boundary M1, but also the case where it is inclined at an angle of 30 degrees or less with respect to the direction perpendicular to the boundary M1.

[0051] Furthermore, the groove 15 may be formed in a straight line, or it may be curved or bent in whole or in part.

[0052] As shown in Figure 4, it is preferable that at least a portion of the multiple grooves 15 are formed on the first side surface S31. This allows for the relaxation of stress that occurs locally between the seal portion 30 and the electrolyte sheet 11 due to differences in thermal expansion, and thus further suppresses damage to the side surface S3 of the electrolyte sheet 11.

[0053] As shown in Figure 3, if the electrolyte sheet 11 has protrusions 14, it is preferable that at least a portion of the multiple grooves 15 are formed on the protrusions 14. This effectively suppresses damage to the protrusions 14, which are particularly prone to chipping and other damage.

[0054] As shown in Figure 4, the plurality of grooves 15 include a first groove 15a, a second groove 15b, and a third groove 15c. The first groove 15a and the second groove 15b are each formed on the first side surface S31. The first groove 15a is formed in a first region 1a on the first main surface S1 side of the first side surface S31, in a side view of the electrolyte sheet 11. The second groove 15b is formed in a second region 1b on the second main surface S2 side of the first side surface S31, in a side view of the electrolyte sheet 11, in a second region 1b on the second main surface S2 side of the first side surface S31, in a side view of the electrolyte sheet 11. The third groove 15c is formed on the second side surface S32.

[0055] Furthermore, if the groove 15 straddles the center C1 in the height direction of the first side surface S31, the groove 15 is recognized as the first groove 15a if the portion formed in the first region 1a is longer than the portion formed in the second region 2a, and otherwise it is recognized as the second groove 15b. Similarly, if the groove 15 straddles the boundary M2 between the second region 2a and the second side surface S32, the groove 15 is recognized as the second groove 15b if the portion formed in the second region 2a is longer than the portion formed in the second side surface S32, and otherwise it is recognized as the third groove 15c.

[0056] It is preferable that the number of first grooves 15a is greater than the number of second grooves 15b.

[0057] It is preferable that the number of first grooves 15a is greater than the number of third grooves 15c. This reduces the stress on the seal portion 30 and prevents the electrolyte sheet 11 from rupturing along the direction perpendicular to the boundary M1.

[0058] The number of second grooves 15b may be greater than or less than the number of third grooves 15c.

[0059] The number of the first groove 15a, the second groove 15b, and the third groove 15c shall be determined by counting the number of grooves observed within a range of 100 μm along the boundary M1 between the first main surface S1 and the side surface S3.

[0060] (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.

[0061] (Modification 1) In the above embodiment, the sealing 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 5, the sealing portion 30 may be joined to the first main surface S1 and the first side surface S31. In this case as well, flexibility in the direction along the boundary M1 can be imparted to the electrolyte sheet 11, thereby suppressing damage to the side surface S3 of the electrolyte sheet 11.

[0062] (Modification 2) In the above embodiment, the sealing portion 30 covers only a part of the first side surface S31, but is not limited to this. As shown in Figure 6, the sealing portion 30 may cover the entire first side surface S31, or it may also cover the first main surface S1.

[0063] Similarly, in the above modified example 1, the sealing portion 30 covers only a part of the second side surface S32, but it is not limited to this. Although not shown, the sealing portion 30 may cover the entire second side surface S32, or it may also cover a part of the second main surface S2.

[0064] (Modification 3) 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.

[0065] (Modification 4) 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 7, the side surface S3 may be flat overall.

[0066] Furthermore, in the above embodiment, the electrolyte sheet 11 has a protrusion 14 formed on the outer edge of the first main surface S1, but as shown in Figure 7, the electrolyte sheet 11 does not have a protrusion 14, and the first main surface S1 may be planar.

[0067] (Modification 5) 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.

[0068] 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 15 Groove 15a First groove 15b Second groove 15c Third groove 12 Oxygen electrode 13 Hydrogen electrode 20 Separator 30 Seal 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 plurality of grooves formed on the side surface and extending in a direction perpendicular to the boundary between the first main surface and the side surface.

2. The side surface comprises a first side surface connected to the first main surface and a second side surface connected to the second main surface and the first side surface, the first side surface being inclined with respect to the first main surface and the second side surface, and at least a portion of the plurality of grooves being formed on the first side surface, the electrolyte sheet for an electrochemical cell according to claim 1.

3. The first side surface includes, in a side view, a first region on the first main surface side from the center of the first side surface in the height direction, and, in a side view, a second region on the second side surface side from the center of the first side surface in the height direction, and the plurality of grooves include, a first groove formed in the first region, and, a second groove formed in the second region, and the number of first grooves is greater than the number of second grooves, the electrolyte sheet for an electrochemical cell according to claim 2.

4. The plurality of grooves include a third groove formed on the second side surface, and the number of first grooves is greater than the number of third grooves, the electrolyte sheet for an electrochemical cell according to claim 3.

5. The electrolyte sheet for an electrochemical cell according to claim 1, having a protrusion formed on the outer edge of the first main surface, wherein at least a portion of the plurality of grooves is formed on the protrusion.

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

Images