WO2026013989A1 - Stack - Google Patents

Abstract

Provided is a stack (10) that can reduce resistance between a conducting plate (13) and a terminal (14). This stack is provided with: a cell (32) that includes an electrolyte (36) that separates a fuel electrode (33) and an air electrode (37) in the thickness direction; a conducting plate that is electrically connected to the cell; a terminal that protrudes in a direction that intersects the thickness direction; and a fusion section (46) where the conducting plate and the terminal are fused to connect the terminal to the conducting plate. The fusion section is provided at an end section (48) of the terminal and an end section (47) of the conducting plate in an overlapping section (45) where a part of the terminal overlaps with a part of the conducting plate; and at the end section of the terminal and the end section of the conducting plate, the fusion section accounts for at least 30% of the width (W) of the terminal in the overlapping section.

Description

stack

The present invention relates to a stack having cells containing an electrolyte that separates an anode and an cathode.

Patent Document 1 discloses prior art technology for providing a joint between a conductive plate and a terminal in a stack comprising a cell containing an electrolyte that separates the fuel electrode and the air electrode in the thickness direction, a conductive plate electrically connected to the cell, and a terminal protruding in a direction intersecting the thickness direction.

Japanese Patent Application Laid-Open No. 2022-107872

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

The present invention was made to meet this demand, and aims to provide a stack that can reduce the resistance between the conductive plate and the terminal.

The first aspect to achieve this objective comprises a cell containing an electrolyte that separates the fuel electrode and air electrode 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 terminal fuse together to connect the terminal to the conductive plate, the fusion portion being 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, 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.

The second aspect is the first aspect, in which there are multiple fused portions in the overlapping portion.

The third aspect is the first or second aspect, in which the fusion zone consists of two lines extending in the width direction of the terminal.

In the fourth aspect, in any of the first to third aspects, the fusion zone penetrates the conductive plate and the terminal at the overlapping portion.

According to the present invention, the fused portion connecting the terminal to the conductive plate is present at the end of the terminal and the end of the conductive plate in 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 fused portion 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.

FIG. 2 is an exploded view of a stack in one embodiment. FIG. 2 is a cross-sectional view of the reaction unit taken along line II-II in FIG. 1. FIG. 2 is a plan view of the conductive plate and the terminal as viewed from the thickness direction of the cell. 4A is a plan view of the overlapping portion in the first embodiment, and FIG. 4B is a cross-sectional view of the overlapping portion taken along line IVb-IVb. 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. 10A is a plan view of an overlapping portion in a second embodiment, and FIG. 10B is a plan view of an overlapping portion in a third embodiment. 10A is a plan view of an overlapping portion in a fourth embodiment, and FIG. 10B is a plan view of an overlapping portion in a fifth embodiment.

Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Figure 1 is a schematic exploded view of a stack 10 in one embodiment. Examples of stack 10 include a polymer electrolyte fuel cell or a solid oxide fuel cell, or a solid oxide electrolysis device. Examples of electrolysis devices include a steam electrolysis cell (SOEC).

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

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

Holes 22 are connected in the thickness direction and form a supply channel 30 (described later) that supplies fuel gas to reaction unit 11. Holes 23 are connected in the thickness direction and form an exhaust channel 31 (described later) through which gas containing gas remaining after the fuel gas has reacted in reaction unit 11 flows. Holes 24 are connected in the thickness direction and form a supply channel that supplies oxidant gas to reaction unit 11. Holes 25 are connected in the thickness direction and form an exhaust channel through which gas containing gas remaining after the fuel gas has reacted in reaction unit 11 flows.

In fuel cells, examples of fuel gas include hydrogen, carbon monoxide, and hydrocarbons, and examples of oxidant gas include oxygen and air. In electrolysis devices, examples of fuel gas include gas containing water vapor and gas containing water vapor and carbon dioxide, and examples of oxidant gas include oxygen. An electrolysis device that uses gas containing water vapor and carbon dioxide as a raw material corresponds to part of a co-electrolysis system that converts gas containing water vapor and carbon dioxide into gas containing hydrogen and carbon monoxide through electrolysis.

Figure 2 is a cross-sectional view of the reaction unit 11 taken along line II-II in Figure 1, showing the components that make up one reaction unit 11 separated in the thickness direction and disassembled. In this embodiment, a reaction unit 11 of a solid oxide stack 10 is described. The thickness of each part is exaggerated in Figure 2.

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, anode frame 27, separator 38, and 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.

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 that makes up the support 34 may be the same as the material that makes up the functional layer 35, or it may be a different material from the material that makes up the functional layer 35. When the material that makes up the support 34 is different from the material that makes up the functional layer 35, an example of the material for the support 34 is stabilized zirconia.

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 when current is passed through it, converting it into hydrogen and oxide ions.

Functional layer 35 contains a catalyst containing Ni and zirconia with Y dissolved therein. Examples of catalysts include Ni, Ni-based alloys, and cermets, which are composites (sintered bodies) of NiO and oxides (electrolytes). Ni is produced in cermets by hydrogen reduction of NiO. An example of the oxide (electrolyte) contained in the cermet is zirconia with Y dissolved therein. Functional layer 35 may also contain a catalyst containing Ni and ceria with Gd dissolved therein.

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 with one or more selected from stabilized zirconia and a ceria-based solid solution.

The air electrode 37 is disposed in the center of the electrolyte 36. In a fuel cell, the air electrode 37 is where a gaseous oxidant (oxygen) reacts with electrons to form oxide ions, and in steam electrolysis, it is where oxide ions release electrons to form oxygen. Examples of materials for the air electrode 37 include perovskite-type oxides such as La1 _{- xSrxMnO3 -δ} , La1 _{-xSrxCoO3 - δ} , La1 _{- xSrxCo1 - YFeYO3 -} δ, and Pr1 _{- xSrxMnO3 -δ} .

The separator 38 is a frame-shaped member arranged around the air electrode 37. An example of the material for the separator 38 is stainless steel. The separator 38 is airtightly joined to the electrolyte 36 using brazing material or the like, avoiding the air electrode 37.

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

The fuel electrode frame 27 is a frame-shaped member disposed between the interconnector 26 and the separator 38. An example of the material for the fuel electrode frame 27 is stainless steel. The fuel electrode frame 27 surrounds the cell 32 and the current collector 39 located in the center of the interconnector 26.

The current collector 39 electrically connects the fuel electrode 33 and the interconnector 26. An example of the material for 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, fuel electrode frame 27, and separator 38 is provided inside the fuel electrode frame 27. A groove 41 provided in the fuel electrode frame 27 connects the fuel chamber 40 to the hole 22 (supply path 30). A groove 42 provided in the fuel electrode frame 27 connects the fuel chamber 40 to the hole 23 (discharge path 31).

The air electrode frame 29 is a frame-shaped member arranged between the interconnector 26 and the separator 38. Examples of materials for the air electrode frame 29 include an insulator such as mica. The air electrode frame 29 surrounds the current collector 43 located 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 limited to this. It is of course possible for the current collector 43 to be a separate member from the interconnector 26.

An air chamber 44 is provided inside the air electrode frame 29, surrounded by the interconnector 26, the air electrode frame 29, and the 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.

Returning to Figure 1, the stack 10 has multiple reaction units 11 connected in series, and conductive plates 13, 17 are connected to the reaction units 11. The conductive plates 13, 17 are plate-shaped members made of a conductive material such as stainless steel, and terminals 14, 18 are connected to them, respectively. The terminals 14, 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, 18 include nickel, nickel-based alloys, copper, copper alloys, and stainless steel.

Insulators 15 and 19 are plate-shaped members made of an insulator. Insulator 15 provides electrical insulation between conductive plate 13 and end plate 16, and insulator 19 provides electrical insulation between conductive plate 17 and end plate 20.

Figure 3 is a plan view of the conductive plate 13 and terminal 14 as viewed from the thickness direction of the cell 32. The middle portion of the conductive plate 13 is not shown in Figure 3. At the overlapping portion 45, part of the terminal 14 overlaps part of the conductive plate 13. The portion of the terminal 14 other than the overlapping portion 45 extends outside the edge of the conductive plate 13.

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).

A fused portion 46 is provided at 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 terminal 14 melting together and solidifying. The terminal 14 is joined to the conductive plate 13 by the fused portion 46.

At least a portion of the molten portion 46 exists at the end 47 of the conductive plate 13 and the 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 left-right dimension in Figure 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 molten portion 46 occupies 30% or more of the width W of the terminal 14 at the overlapping portion 45 at the end 48 of the terminal 14 and the end 47 of the conductive plate 13. This means that the portion of the molten portion 46 that occupies 30% or more of the width W of the terminal 14 exists at least in part at the end 47 and at least in part at the end 48.

In this embodiment, the molten portion 46 penetrates the conductive plate 13 and the terminal 14. Because the molten portion 46 shrinks when it solidifies, 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.

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 the surface with the larger exposed area of the molten portion 46 is examined to determine whether the molten portion 46 exists in a portion that occupies 30% or more of the width W of the terminal 14. In this embodiment, the molten portion 46 is created 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.

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 overlapping portion 45 at the ends 47 and 48, the current flowing from the terminal 14 to the conductive plate 13 flows mainly through the fused portion 46 at the end 47, and the current flowing from the conductive plate 13 to the terminal 14 flows mainly through the fused portion 46 at the end 48. The fused portion 46 can shorten the current path, and the presence of the fused portion 46 at the ends 47 and 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.

Figure 5 is a diagram showing the relationship between the ratio of the fused portion 46 to the width W of the terminal 14 and the resistance between the conductive plate 13 and the terminal 14. In Figure 5, the horizontal axis represents the ratio of the fused portion 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 fused portion 46 is equal to the width W of the terminal 14 (the ratio is 100%).

According to Figure 5, the resistance increases as the ratio of the fused portion 46 to the width W of the terminal 14 decreases, and when the ratio falls below 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 the conductive plate 13 and the terminal 14 at the overlapping portion 45, the ratio of the fused portion 46 to the width W of the terminal 14 is preferably 30% or more, more preferably 40% or more, and even more preferably 50% or more.

Returning to Figure 4(a), the explanation will be made. There are multiple fusion zones 46 (two in this embodiment) in the overlapping portion 45. Compared to when there is only one fusion zone in the overlapping portion 45 that has the same length and width as each fusion zone 46, 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.

In this embodiment, there are two fusion zones 46 that extend in the width direction of the terminal 14. This makes it easy to provide fusion zones 46 in portions of the ends 47, 48 that occupy 30% or more of the width W of the terminal 14. This reduces the time required to weld the terminal 14.

Figure 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 assigned the same reference numerals, and the following description will be omitted (the same applies to Figures 6(b), 7(a), and 7(b)).

In the 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 the end 47 of the conductive plate 13, and two are provided intermittently at the 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.

Figure 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 portions 46 extend in the width direction of the terminal 14. One fusion portion 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 ends 47 and 48. The fusion portions 46 are provided in portions of the ends 47 and 48 that occupy 30% or more of the width W of the terminal 14. The fourth embodiment reduces the resistance in the overlapping portion 50, and further improves the joining strength in the overlapping portion 50 by providing the fusion portion 46 between the ends 47 and 48.

Figure 7(a) is a plan view of the overlapping portion 51 in the fourth embodiment. In the overlapping portion 51 where the terminal 14 and the conductive plate 13 overlap, four fused portions 46 extend in the length direction of the terminal 14. Four fused portions 46 are provided between the end portion 47 of the conductive plate 13 and the end portion 48 of the terminal 14. The total number of fused 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 fused portions 46 connecting the end portions 47 and 48.

Figure 7(b) is a plan view of the overlapping portion 52 in the fifth embodiment. In the overlapping portion 52 where the terminal 14 and the conductive plate 13 overlap, the fused portion 46 connects two ends extending in the width direction of the terminal 14. The fused portion 46 connects the end 47 of the conductive plate 13 to the end 48 of the terminal 14. The fused portion 46 is provided in each of the ends 47, 48 at a portion that occupies 30% or more of the width W of the terminal 14. The fifth embodiment reduces the resistance in the overlapping portion 52, and further improves the joining strength in the overlapping portion 52 by using the fused portion 46 that connects the end 47 and the end 48.

The present invention has been described above based on the embodiments, but the present invention is in no way limited to the above embodiments, and it can be easily imagined that various improvements and modifications are possible within the scope of the invention.

In the embodiment, a 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.

In the embodiment, the shape of the cells 32 and 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 conductive plates 13 and 17 can be set to any shape, such as a circle, ellipse, or polygon other than a rectangle.

In the embodiment, an anode-supported cell 32 has been described, but this is not necessarily limited to this. It is of course possible to use an electrolyte-supported or metal-supported cell 32.

In the embodiment, a solid oxide stack 10 has been described, but this 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 passages 30 and discharge passages 31, etc., to create a solid polymer stack 10.

10 Stack 13 Conductive plate 14 Terminal 32 Cell 33 Anode 36 Electrolyte 37 Cathode 45, 49, 50, 51, 52 Overlapped portion 46 Welded portion 47 Edge of conductive plate 48 Edge of terminal W Width of terminal

Claims (4)

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. The stack of claim 1, wherein multiple molten portions exist in the overlapping portion. The stack described in claim 2, wherein the fusion zone consists of two lines extending in the width direction of the terminal. A stack as described in any one of claims 1 to 3, wherein the fusion zone penetrates the conductive plate and the terminal at the overlapping portion.