Stack

Abstract

To provide a stack capable of reducing resistance between a conductive plate and a terminal.SOLUTION: The stack includes a cell including an electrolyte separating a fuel electrode and an air electrode from each other in a thickness direction, a conductive plate electrically connected to the cell, a terminal protruding in a direction intersecting the thickness direction, and a melting portion where the conductive plate and the terminal are melted to connect the terminal to the conductive plate, wherein the melting portion is present at an end portion of the terminal and an end portion of the conductive plate in an overlapping portion where a part of the terminal overlaps a part of the conductive plate, and the melting portion occupies 30% or more of a width of the terminal in the overlapping portion in the end portion of the terminal and the end portion of the conductive plate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a stack comprising cells containing an electrolyte separating an anode and a cathode. [Background technology]

[0002] In a stack including a cell containing an electrolyte that separates an anode and an cathode in the thickness direction, a conductive plate electrically connected to the cell, and a terminal protruding in a direction intersecting the thickness direction, prior art in which a joint is provided between the conductive plate and the terminal is disclosed in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-107872 Summary of the Invention [Problem to be solved by the invention]

[0004] In the prior art, Joule heat generated at the junction between the conductive plate and the terminal results in power loss, so there is a demand for a technique to reduce the resistance between the conductive plate and the terminal.

[0005] The present invention has been made to meet this demand, and has as its object to provide a stack that can reduce the resistance between the conductive plates and the terminals. [Means for solving the problem]

[0006] A first aspect for achieving this object comprises a cell containing an electrolyte that separates an anode and an cathode in the thickness direction, a conductive plate electrically connected to the cell, a terminal protruding in a direction intersecting the thickness direction, and a fusion portion where the conductive plate and the terminal fuse together to connect the terminal to the conductive plate, wherein the fusion portion is present at an end of the terminal and an end of the conductive plate at an overlapping portion where a portion of the terminal overlaps a portion of the conductive plate, and at the end of the terminal and the end of the conductive plate, the fusion portion occupies 30% or more of the width of the terminal at the overlapping portion.

[0007] In the second embodiment, in the first embodiment, a plurality of fused portions are present in the overlapping portion.

[0008] In a third aspect, in the first or second aspect, the fusion zones are two fusion zones extending in the width direction of the terminal.

[0009] In a fourth aspect, in any one of the first to third aspects, the fusion zone penetrates the conductive plate and the terminal at the overlapping portion. [Effects of the Invention]

[0010] According to the present invention, the fusion zone connecting the terminal to the conductive plate is present at the end of the terminal and the end of the conductive plate at the overlapping portion where part of the terminal overlaps part of the conductive plate. At the end of the terminal and the end of the conductive plate, the fusion zone occupies 30% or more of the width of the terminal at the overlapping portion, thereby reducing the resistance between the conductive plate and the terminal at the overlapping portion. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is an exploded view of a stack in one embodiment. [Figure 2] FIG. 2 is a cross-sectional view of the reaction unit taken along line II-II in FIG. 1. [Figure 3] FIG. 2 is a plan view of the conductive plate and the terminal as viewed from the thickness direction of the cell. [Figure 4] FIG. 4(a) is a plan view of the overlapping portion in the first embodiment, and FIG. 4(b) is a cross-sectional view of the overlapping portion taken along line IVb-IVb. [Figure 5] 10 is a diagram showing the relationship between the ratio of the fusion zone to the width of the terminal and the resistance between the conductive plate and the terminal. FIG. [Figure 6] FIG. 10(a) is a plan view of the overlapping portion in the second embodiment, and FIG. 10(b) is a plan view of the overlapping portion in the third embodiment. [Figure 7] FIG. 10(a) is a plan view of the overlapping portion in the fourth embodiment, and FIG. 10(b) is a plan view of the overlapping portion in the fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Fig. 1 is a schematic exploded view of a stack 10 in one embodiment. The stack 10 may be, for example, a polymer electrolyte fuel cell or a solid oxide fuel cell, or a solid oxide electrolysis device. The electrolysis device may, for example, include a steam electrolysis cell (SOEC).

[0013] The stack 10 includes a laminate 12 in which a plurality of reaction units 11 are stacked. The stack 10 includes, in order from the outside of one end of the laminate 12 in the thickness direction toward the outside, a conductive plate 13, an insulator 15, and an end plate 16, and also includes, in order from the outside of the other end of the laminate 12 in the thickness direction toward the outside, a conductive plate 17, an insulator 19, and an end plate 20. The conductive plates 13 and 17 include terminals 14 and 18, respectively, for connection to an electric circuit (not shown).

[0014] A plurality of holes 21 penetrating in the thickness direction of the laminate 12 are provided around the periphery of the laminate 12, the conductive plates 13 and 17, the insulators 15 and 19, and the end plates 16 and 20. The laminate 12, the conductive plates 13 and 17, the insulators 15 and 19, and the end plates 16 and 20 are fastened together by members (not shown) such as bolts placed in the holes 21. Four holes 22-25 penetrating in the thickness direction of the laminate 12 are provided around the periphery of the laminate 12, the conductive plate 13, the insulator 15, and the end plate 16.

[0015] The holes 22 are connected in the thickness direction and form a supply path 30 (described later) that supplies fuel gas to the reaction units 11. The holes 23 are connected in the thickness direction and form an exhaust path 31 (described later) through which a gas containing gas remaining after the fuel gas has reacted in the reaction units 11 flows. The holes 24 are connected in the thickness direction and form a supply path that supplies oxidant gas to the reaction units 11. The holes 25 are connected in the thickness direction and form an exhaust path through which a gas containing gas remaining after the reaction in the reaction units 11 flows.

[0016] In a fuel cell, examples of the fuel gas include hydrogen, carbon monoxide, and hydrocarbon, and examples of the oxidant gas include oxygen and air. In an electrolysis device, examples of the fuel gas include a gas containing water vapor and a gas containing water vapor and carbon dioxide, and examples of the oxidant gas include oxygen. An electrolysis device that uses a gas containing water vapor and carbon dioxide as a raw material corresponds to part of a co-electrolysis system that converts the gas containing water vapor and carbon dioxide into a gas containing hydrogen and carbon monoxide by electrolysis.

[0017] Figure 2 is a cross-sectional view of the reaction unit 11 taken along line II-II in Figure 1, showing the components constituting one reaction unit 11 separated in the thickness direction and exploded. In this embodiment, a reaction unit 11 of a solid oxide type stack 10 will be described. In Figure 2, the thickness of each part is exaggerated.

[0018] The reaction unit 11 includes, in order in the thickness direction, an interconnector 26, an anode frame 27, a separator-equipped cell 28, and an air electrode frame 29. The separator-equipped cell 28 includes a cell 32 and a separator 38 disposed in the cell 32. The holes 22 provided in the interconnector 26, the anode frame 27, the separator 38, and the air electrode frame 29 are connected in the thickness direction to form a supply channel 30, and the holes 23 connected in the thickness direction form a discharge channel 31.

[0019] The cell 32 includes, in order, an anode 33, an electrolyte 36, and an air cathode 37. The anode 33 includes a support 34 and a functional layer 35. The support 34 is a flat, porous body having a higher gas permeability than the porosity of the functional layer 35. The support 34 mainly functions to support the functional layer 35. The material constituting the support 34 may be the same as the material constituting the functional layer 35, or may be a different material from the material constituting the functional layer 35. When the material constituting the support 34 is different from the material constituting the functional layer 35, an example of the material of the support 34 is stabilized zirconia.

[0020] In a fuel cell, the functional layer 35 has the function of reacting oxide ions supplied from the electrolyte 36 with fuel gas to generate electrons, and in steam electrolysis, it has the function of electrolyzing water vapor by passing electricity through it and converting it into hydrogen and oxide ions.

[0021] The functional layer 35 includes a catalyst containing Ni and zirconia with Y dissolved therein. Examples of the catalyst include Ni, Ni-based alloys, and cermet, which is a composite (sintered body) of NiO and an oxide (electrolyte). In the cermet, Ni is produced by hydrogen reduction of NiO. Examples of the oxide (electrolyte) contained in the cermet include zirconia with Y dissolved therein. The functional layer 35 may also include a catalyst containing Ni and ceria with Gd dissolved therein.

[0022] The electrolyte 36 is a plate-shaped member that exhibits oxide ion conductivity under the operating conditions of the cell 32. Examples of the electrolyte 36 include stabilized zirconia, a ceria-based solid solution, and a solid solution of alumina and one or more selected from the group consisting of stabilized zirconia and a ceria-based solid solution.

[0023] The air electrode 37 is placed in the center of the electrolyte 36. In a fuel cell, the air electrode 37 is the site where the gas phase oxidant (oxygen) reacts with electrons to become oxide ions, and in steam electrolysis, it is the site where the oxide ions release electrons to become oxygen. The material of the air electrode 37 is La, a perovskite oxide. 1-X Sr X MnO 3-δ ,La 1-X Sr X CoO 3-δ ,La 1-X Sr X Co 1-Y Fe Y O 3-δ ,Pr 1-X Sr X MnO 3-δ is exemplified.

[0024] The separator 38 is a frame-shaped member disposed around the air electrode 37. The separator 38 is made of, for example, stainless steel. The separator 38 is airtightly joined to the electrolyte 36 with brazing material or the like, avoiding the air electrode 37.

[0025] The interconnectors 26 are conductive plate-like members arranged on both sides in the thickness direction of the cell 32. The interconnectors 26 electrically connect the reaction units 11 adjacent to each other in the thickness direction. An example of the material of the interconnectors 26 is stainless steel.

[0026] The fuel electrode frame 27 is a frame-shaped member disposed between the interconnector 26 and the separator 38. The material of the fuel electrode frame 27 is, for example, stainless steel. The fuel electrode frame 27 surrounds the cells 32 and a current collector 39 provided in the center of the interconnector 26.

[0027] The current collector 39 electrically connects the anode 33 and the interconnector 26. An example of the material of the current collector 39 is a porous body made of a gas-permeable metal such as Ni. A fuel chamber 40 surrounded by the interconnector 26, the anode frame 27, and the separator 38 is provided inside the anode frame 27. A groove 41 provided in the anode frame 27 connects the fuel chamber 40 and the hole 22 (supply path 30). A groove 42 provided in the anode frame 27 connects the fuel chamber 40 and the hole 23 (discharge path 31).

[0028] The air electrode frame 29 is a frame-shaped member disposed between the interconnector 26 and the separator 38. An example of the material of the air electrode frame 29 is an insulator such as mica. The air electrode frame 29 surrounds a current collector 43 provided in the center of the interconnector 26. The current collector 43 electrically connects the air electrode 37 and the interconnector 26. In this embodiment, the current collector 43 is formed integrally with the interconnector 26, but this is not limiting. It is of course possible for the current collector 43 to be a member separate from the interconnector 26.

[0029] An air chamber 44 is provided inside the air electrode frame 29 and is surrounded by the interconnector 26, the air electrode frame 29, and a separator 38. The separator 38 separates the fuel chamber 40 from the air chamber 44, preventing the fuel gas in the fuel chamber 40 and the oxidizer gas in the air chamber 44 from mixing.

[0030] Returning to Figure 1, the stack 10 has a plurality of reaction units 11 connected in series, and conductive plates 13 and 17 are connected to the reaction units 11. The conductive plates 13 and 17 are plate-shaped members made of a conductive material such as stainless steel, and terminals 14 and 18 are connected to them, respectively. The terminals 14 and 18 protrude outside the stack 12 in a direction intersecting the thickness direction of the reaction units 11. Examples of materials for the terminals 14 and 18 include nickel, nickel-based alloys, copper, copper alloys, and stainless steel.

[0031] The insulators 15 and 19 are plate-shaped members made of an insulator. The insulator 15 electrically insulates the conductive plate 13 from the end plate 16, and the insulator 19 electrically insulates the conductive plate 17 from the end plate 20.

[0032] 3 is a plan view of the conductive plate 13 and the terminal 14 as viewed from the thickness direction of the cell 32. The middle portion of the conductive plate 13 is not shown in FIG. 3. A portion of the terminal 14 overlaps a portion of the conductive plate 13 at an overlapping portion 45. The portion of the terminal 14 other than the overlapping portion 45 extends outside the edge of the conductive plate 13.

[0033] Fig. 4(a) is a plan view of the overlapping portion 45 in the first embodiment. Fig. 4(b) is a cross-sectional view of the overlapping portion 45 taken along line IVb-IVb. Part of the conductive plate 13 is omitted from Fig. 4(a) (the same applies to Figs. 6(a), 6(b), 7(a), and 7(b)), and part of the conductive plate 13 and terminal 14 are omitted from Fig. 4(b).

[0034] A fused portion 46 is provided in the overlapping portion 45. The fused portion 46 is created by laser welding, in which a laser beam is irradiated onto the overlapping portion 45 from the terminal 14 toward the conductive plate 13. The fused portion 46 is formed by the conductive plate 13 and the terminal 14 melting together and solidifying. The terminal 14 is joined to the conductive plate 13 by the fused portion 46.

[0035] At least a portion of the fused portion 46 exists at an end 47 of the conductive plate 13 and an end 48 of the terminal 14 at the overlapping portion 45. The end 47 of the conductive plate 13 extends from the edge 13a of the conductive plate 13 to 20% of the length of the overlapping portion 45 (the dimension in the left-right direction in FIG. 4(b)). The end 48 of the terminal 14 extends from the edge 14a of the terminal 14 to 20% of the length of the overlapping portion 45. The fused portion 46 occupies 30% or more of the width W of the terminal 14 at the end 48 of the terminal 14 and the end 47 of the conductive plate 13. This means that a portion of the fused portion 46 occupying 30% or more of the width W of the terminal 14 exists at at least a portion of the end 47 and at least a portion of the end 48.

[0036] In this embodiment, the molten portion 46 penetrates the conductive plate 13 and the terminal 14. The molten portion 46 shrinks when solidifying, and therefore deformation of the overlap portion 45 due to shrinkage of the molten portion 46 can be reduced compared to when the molten portion 46 does not penetrate the conductive plate 13 and the terminal 14.

[0037] If the molten portion 46 penetrates the conductive plate 13 and the terminal 14, it is determined which surface of the conductive plate 13 or the terminal 14 has the larger exposed molten portion 46, and it is determined whether the molten portion 46 exists in a portion occupying 30% or more of the width W of the terminal 14 on the surface with the larger exposed area of ​​the molten portion 46. In this embodiment, the molten portion 46 is formed by irradiating the overlapping portion 45 from the terminal 14 toward the conductive plate 13 with a laser beam, so the area of ​​the molten portion 46 exposed on the terminal 14 is larger than the area of ​​the molten portion 46 exposed on the conductive plate 13. Therefore, it is determined whether the molten portion 46 exists in a portion of the terminal 14 at the overlapping portion 45 that occupies 30% or more of the width W of the terminal 14.

[0038] At the overlapping portion 45, current flows between the terminal 14 and the conductive plate 13 mainly through the edge of the fused portion 46. When the fused portion 46 is present at the end 48 of the terminal 14 and the end 47 of the conductive plate 13, and the fused portion 46 occupies 30% or more of the width W of the terminal 14 at the ends 47, 48, the current flowing from the terminal 14 to the conductive plate 13 flows mainly through the fused portion 46 provided at the end 47, and the current flowing from the conductive plate 13 to the terminal 14 flows mainly through the fused portion 46 provided at the end 48. The current path taken by the fused portion 46 can be shortened, and the presence of the fused portion 46 at the ends 47, 48 can increase the cross-sectional area of ​​the fused portion 46, thereby reducing the resistance between the conductive plate 13 and the terminal 14 at the overlapping portion 45.

[0039] Fig. 5 is a diagram showing the relationship between the ratio of the fusion zone 46 to the width W of the terminal 14 and the resistance between the conductive plate 13 and the terminal 14. In Fig. 5, the horizontal axis represents the ratio of the fusion zone 46 to the width W, and the vertical axis represents the resistance between the conductive plate 13 and the terminal 14. The resistance (vertical axis) is plotted as the ratio of the resistance to the reference when the width of the fusion zone 46 is equal to the width W of the terminal 14 (the ratio is 100%).

[0040] 5, the resistance increases as the ratio of fusion zone 46 to width W of terminal 14 decreases, and when the ratio is less than 30%, the rate of increase in resistance becomes dramatically greater than the rate of decrease in the ratio. Therefore, in order to reduce the resistance between conductive plate 13 and terminal 14 at overlapping portion 45, the ratio of fusion zone 46 to width W of terminal 14 is preferably 30% or more, more preferably 40% or more, and even more preferably 50% or more.

[0041] Returning to Figure 4(a), the explanation will be given below. There are multiple fusion zones 46 (two in this embodiment) in the overlapping portion 45. Compared to the case where one fusion zone of the same length and width as each fusion zone 46 is provided in the overlapping portion 45, the total cross-sectional area of ​​the fusion zones 46 can be increased by the number of fusion zones 46. Therefore, the resistance in the overlapping portion 45 can be reduced.

[0042] In this embodiment, there are two fusion zones 46 extending in the width direction of terminal 14. This allows fusion zones 46 to be easily provided in portions of end portions 47, 48 that occupy 30% or more of width W of terminal 14. This reduces the time required to weld terminal 14.

[0043] Fig. 6(a) is a plan view of the overlapping portion 49 in the second embodiment. In the second embodiment, the same parts as those described in the first embodiment are denoted by the same reference numerals, and the following description will be omitted (the same applies to Figs. 6(b), 7(a), and 7(b)).

[0044] In an overlapping portion 49 where the terminal 14 and the conductive plate 13 overlap, four fused portions 46 extend in the width direction of the terminal 14. Two fused portions 46 are provided intermittently at an end 47 of the conductive plate 13, and two fused portions 46 are provided intermittently at an end 48 of the terminal 14. The fused portions 46 are provided in portions of the end portions 47, 48 that occupy 30% or more of the width W of the terminal 14. As with the first embodiment, the second embodiment can reduce the resistance between the conductive plate 13 and the terminal 14 in the overlapping portion 49.

[0045] 6(b) is a plan view of the overlapping portion 50 in the third embodiment. In the overlapping portion 50 where the terminal 14 and the conductive plate 13 overlap, three fusion zones 46 extend in the width direction of the terminal 14. One fusion zone 46 is provided at the end 47 of the conductive plate 13, one is provided at the end 48 of the terminal 14, and one is provided between the end 47 and the end 48. The fusion zones 46 are provided in portions of the end 47, 48 that occupy 30% or more of the width W of the terminal 14. In the fourth embodiment, the resistance in the overlapping portion 50 is reduced, and further, the fusion zone 46 provided between the end 47 and the end 48 can improve the joining strength in the overlapping portion 50.

[0046] 7(a) is a plan view of an overlapping portion 51 in the fourth embodiment. In the overlapping portion 51 where the terminal 14 and the conductive plate 13 overlap, four fusion portions 46 extend in the length direction of the terminal 14. The four fusion portions 46 are provided between an end 47 of the conductive plate 13 and an end 48 of the terminal 14. The total number of fusion portions 46 occupies 30% or more of the width W of the terminal 14 at the ends 47, 48. In the fourth embodiment, the resistance between the conductive plate 13 and the terminal 14 at the overlapping portion 51 can be reduced by the fusion portions 46 that connect the end 47 and the end 48.

[0047] 7(b) is a plan view of overlapping portion 52 in the fifth embodiment. In overlapping portion 52 where terminal 14 and conductive plate 13 overlap, fusion portion 46 connects two ends extending in the width direction of terminal 14. Fusion portion 46 connects end portion 47 of conductive plate 13 and end portion 48 of terminal 14. Fusion portion 46 is provided in each of ends 47, 48 at a portion occupying 30% or more of width W of terminal 14. In the fifth embodiment, resistance in overlapping portion 52 is reduced, and further, joining strength in overlapping portion 52 can be improved by fusion portion 46 connecting end portion 47 and end portion 48.

[0048] The present invention has been described above based on the embodiments, but the present invention is not limited to the above embodiments, and it can be easily inferred that various improvements and modifications are possible within the scope of the present invention.

[0049] In the embodiment, the fusion zone 46 that joins the conductive plate 13 and the terminal 14 has been described, but this is not necessarily limited to this. It is of course possible to provide a fusion zone (not shown) that joins the conductive plate 17 and the terminal 18 in the same manner as the fusion zone 46 that joins the conductive plate 13 and the terminal 14.

[0050] In the embodiment, the shape of the cells 32 and the conductive plates 13 and 17 when viewed in the thickness direction is rectangular, but this is not necessarily limited to this. The shape of the cells 32 and the conductive plates 13 and 17 can be set to any shape, such as a circle, an ellipse, or a polygon other than a rectangle.

[0051] In the embodiment, the fuel electrode-supported cell 32 has been described, but the present invention is not limited to this. It is of course possible to use an electrolyte-supported or metal-supported cell 32.

[0052] Although the embodiment has been described as a solid oxide stack 10, the present invention is not necessarily limited to this. It is of course possible to provide a passage for flowing cooling water around the cells 32 in addition to the supply passage 30 and the discharge passage 31, thereby forming a solid polymer stack 10. [Explanation of symbols]

[0053] 10 stacks 13 Conductive plate 14 terminals 32 cells 33 Fuel electrode 36 Electrolytes 37 Air electrode 45, 49, 50, 51, 52 overlapping parts 46 Welding section 47 Edge of conductive plate 48 Terminal End W Terminal width

Claims

1. a cell including an electrolyte separating an anode and a cathode through its thickness; a conductive plate electrically connected to the cell; a terminal protruding in a direction intersecting the thickness direction; a fusion portion where the conductive plate and the terminal are fused to connect the terminal to the conductive plate, the fused portion is present at an end of the terminal and an end of the conductive plate at an overlapping portion where a portion of the terminal overlaps a portion of the conductive plate, A stack in which the fusion zone at the end of the terminal and the end of the conductive plate occupies 30% or more of the width of the terminal at the overlapping portion.

2. The stack according to claim 1 , wherein a plurality of the fused portions are present in the overlapping portion.

3. 3. The stack according to claim 2, wherein the fusion zones are two fusion zones extending in the width direction of the terminals.

4. The stack according to claim 1 , wherein the fusion zone penetrates the conductive plate and the terminal at the overlapping portion.

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