Metal member, electrode terminals equipped with the metal member, and energy storage module

Abstract

This invention provides a technology to reduce the risk of molten metal scattering when welding a metal component comprising a first metal component and a second metal component that are superimposed on each other to another metal component. [Solution] The metal member disclosed herein comprises a first metal member and a second metal member. The second member has a space between itself and the first member in which gas can be retained. The second member has a ventilation hole that connects the space to the outside air.

Description

Technical Field

[0001] The present disclosure relates to a metal member, an electrode terminal including the metal member, and a power storage module.

Background Art

[0002] In recent years, secondary batteries such as lithium ion secondary batteries and power storage modules including the secondary batteries have become increasingly widespread. This type of secondary battery and power storage module are suitably used, for example, as power sources for driving vehicles such as battery electric vehicles (BEVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and the like.

[0003] Japanese Patent Application Laid-Open No. 2001-87879 discloses a laser welding method in which laser light is irradiated onto a plurality of workpieces to be welded that overlap each other, and the workpieces are melted and joined to each other. In this method, a hole having a diameter smaller than the planned joining diameter is previously formed in a workpiece different from the workpiece onto which the laser light is first irradiated, and laser light having a diameter larger than the diameter of this hole is irradiated onto a position corresponding to the hole in the workpiece in which the hole is not formed, and the workpieces are melted and joined to each other. The publication describes that the hole is a vent hole. Therefore, when impurities are present between the workpieces to be welded, the evaporation gas generated by the evaporation of these impurities due to the heat of melting can escape through the hole. As a result, a good welding state is realized, and sufficient joining strength can be obtained.

[0004] The laser lap welding structure disclosed in Japanese Patent Publication No. 2019-166533 is achieved by joining a first member, which is positioned facing the side of the laser beam irradiation, and a second member, which is stacked on top of the first member in contact with the side opposite to the irradiation side, by irradiating them with laser light. The first member has at least one through-hole drilled in the direction of overlap with the second member. The first member and the second member are joined by a weld that extends from the overlapping region where the first member and the second member overlap and in contact, to the through-hole region where the through-hole is projected onto the second member, including a part of the boundary between the overlapping region and the through-hole region. The publication states that this configuration can improve the joining strength of the stacked members.

[0005] Japanese Patent Publication No. 2020-19061 discloses a method for manufacturing a joined structure comprising a first member made of a plated iron-based material and a second member made of a different material from the first member. This manufacturing method includes the steps of: forming an insertion hole in the second member; overlapping the first member and the second member so that the insertion hole faces the first member; inserting an insertion member made of an iron-based material, which has an insertion portion and a non-insertion portion and a through hole communicating from the insertion portion to the non-insertion portion, into the insertion hole of the second member until the insertion member abuts against the first member; and forming a weld metal portion at the abutment point between the first member and the insertion member to join the first member and the insertion member. The publication states that with this configuration, a first member made of a plated iron-based material and a second member made of a different material from the first member can be joined in a sound state without porosity defects and without creating a gap between the two members. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2001-87879 [Patent Document 2] Japanese Patent Publication No. 2019-166533 [Patent Document 3] Japanese Patent Publication No. 2020-19061 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] When welding another metal member to a metal member comprising a first metal member and a second metal member superimposed on each other, if there is a space between the first and second members where gas can accumulate, for example, the heat applied may cause the gas in that space to expand. This gas may cause molten metal to splatter into the surroundings. Such splatter of molten metal is undesirable because it may degrade the welding quality between the metal member and the other member.

[0008] Therefore, the present invention has been made in view of the above circumstances, and its object is to provide a technology that reduces the risk of molten metal scattering when welding a metal member comprising a first metal member and a second metal member superimposed on each other to another metal member. [Means for solving the problem]

[0009] The technology disclosed herein provides a metal member comprising a first metal member and a second metal member. The second member has a space between itself and the first member in which gas can be retained. The second member has a vent that connects the space to the outside air. This configuration reduces the risk of molten metal splattering when welding a metal member comprising the first and second metal members superimposed on each other to another metal member.

[0010] The technology disclosed herein provides an electrode terminal for use in an energy storage device. The electrode terminal comprises the metal member described above. This configuration reduces the risk of molten metal splattering when welding the metal member to other metal members. This improves the welding quality between the electrode terminal and other members.

[0011] The technology disclosed herein provides an energy storage module comprising electrode terminals and busbars. The energy storage module comprises the aforementioned metal members. The electrode terminals include a first member and a second member. The busbars include a third member. This configuration reduces the risk of molten metal splattering when welding the electrode terminals and the busbars. As a result, an energy storage module with improved welding quality between the electrode terminals and the busbars can be constructed. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a perspective view of the energy storage module 100. [Figure 2] Figure 2 is a cross-sectional view taken along line II-II in Figure 1. [Figure 3] Figure 3 is a view of the busbar 14 from the upper surface 141 side. [Modes for carrying out the invention]

[0013] The following describes one embodiment of the energy storage device disclosed herein. The embodiment described herein is not limited to the technology disclosed herein. Unless otherwise specified, the technology disclosed herein is not limited to the embodiment described herein. The drawings are schematic and do not necessarily reflect the actual object. Components and parts that perform the same function are appropriately denoted by the same reference numeral, and redundant explanations may be omitted. In the drawings, the reference numerals "R", "L", "U", "D", "F", and "Rr" indicate "right", "left", "up", "down", "front", and "back", respectively. The notation "A~B" indicating a numerical range means "A or more and B or less" unless otherwise specified, and also includes the meaning of "greater than A and less than B".

[0014] In this specification, "energy storage device" refers to a device in which charging and discharging occur through the movement of a charge carrier between a pair of electrodes (positive and negative electrodes) via an electrolyte. Energy storage devices include secondary batteries such as lithium-ion secondary batteries, nickel-metal hydride batteries, and nickel-cadmium batteries; and capacitors such as lithium-ion capacitors and electric double-layer capacitors. An energy storage device may be, for example, a lithium-ion secondary battery.

[0015] Figure 1 is a perspective view of the energy storage module 100. The energy storage module 100 is the energy storage module to be manufactured by the manufacturing method disclosed herein. As shown in Figure 1, the energy storage module 100 comprises a plurality of energy storage devices 12 and a busbar 14. As shown in Figure 1, each energy storage device 12 is arranged so that its first surface 30a faces the other. Here, the plurality of energy storage devices 12 are arranged in a direction from one first surface 30a of each energy storage device 12 toward the other first surface 30a. The direction in which the plurality of energy storage devices 12 are arranged is the direction from the rear (Rr) side toward the front (F) side in Figure 1. Hereinafter, the arrangement in which the plurality of energy storage devices 12 are arranged will also be referred to as the "arrangement direction P".

[0016] In the configuration shown in Figure 1, the energy storage device 12 comprises a rectangular parallelepiped case 30, which has a pair of opposing first faces 30a, a pair of opposing second faces 30b, and a bottom face 30c. The first faces 30a are rectangular in shape and are the largest surface area of ​​the case 30. As shown in Figure 1, the pair of opposing first faces 30a are surfaces extending from a pair of opposing long sides of the bottom face 30c. The second faces 30b are rectangular in shape and are the surfaces sandwiched between the pair of opposing first faces 30a. As shown in Figure 1, the pair of opposing second faces 30b are surfaces extending from a pair of opposing short sides of the bottom face 30c.

[0017] The energy storage device 12 comprises, for example, a case 30, an electrode body (not shown) housed within the case 30, and an electrolyte (not shown). The case 30 comprises a main body 31 and a sealing plate 32, as shown in Figure 1. The main body 31 is, for example, a member that houses the electrode body and the electrolyte. The main body 31 here has a rectangular parallelepiped shape with one side open. In the configuration shown in Figure 1, the main body 31 has a pair of opposing first surfaces 30a, a pair of opposing second surfaces 30b, and a bottom surface 30c. Here, the bottom surface 30c and the opening are opposite each other. The sealing plate 32 is, for example, a member that closes the opening of the main body 31. The sealing plate 32 has a shape corresponding to the opening of the main body 31, and here it is rectangular (including substantially rectangular; the same applies hereinafter). The sealing plate 32 has a first through hole (not shown) and a second through hole 322 (see Figure 2). The first through hole is through which the positive electrode terminal 40 is inserted. The second through hole 322 is through which the negative electrode terminal 50 is inserted. The electrode body and electrolyte of the energy storage device 12 can be any electrode body and electrolyte of this type of energy storage device (for example, a lithium-ion secondary battery) without any particular limitations.

[0018] In this embodiment, the energy storage device 12 includes a positive terminal 40 and a negative terminal 50 in a case 30. In the configuration shown in Figures 1 and 2, the positive terminal 40 and the negative terminal 50 are attached to a sealing plate 32. The negative terminal 50 will be described first below.

[0019] Figure 2 is a sectional view taken along line II-II of Figure 1. In Figure 2, a cross-section near the connection portion between the bus bar 14 and the negative electrode terminal 50 is shown enlarged. As shown in Figure 2, the negative electrode terminal 50 has a negative electrode current collector terminal 52 and a negative electrode external terminal 54. The negative electrode current collector terminal 52 is, for example, a member connected to the negative electrode of an electrode body (not shown). In this embodiment, the negative electrode current collector terminal 52 is in a flat plate shape. The negative electrode current collector terminal 52 is arranged along the inner surface 32d of the sealing plate 32. The negative electrode current collector terminal 52 is connected to the negative electrode of the electrode body, for example, via a current collector plate (not shown). The negative electrode current collector terminal 52 has a through hole 52h. In this embodiment, the negative electrode current collector terminal 52 is connected to the negative electrode external terminal 54 by inserting a part of the negative electrode external terminal 54 into the through hole 52h. The negative electrode current collector terminal 52 is preferably, for example, copper or a copper alloy (an alloy containing at least 70% by mass of copper among all components. The same applies hereinafter).

[0020] The negative electrode external terminal 54 is, for example, a portion connected to the bus bar 14. In this embodiment, the negative electrode external terminal 54 has a portion arranged inside the case 30 and a portion arranged outside the case 30. As shown in Figure 2, the negative electrode external terminal 54 includes a first member 56 and a second member 58. The first member 56 is, for example, a portion connected to the negative electrode current collector terminal 52. In this embodiment, the first member 56 includes a connection portion 56a and a shaft portion 56b. The connection portion 56a is, for example, a portion connected to the second member 58. In this embodiment, the connection portion 56a is in a disc shape. Here, the connection portion 56a is housed inside the recess 582 of the second member 58. The shaft portion 56b is, for example, a portion connected to the negative electrode current collector terminal 52. In this embodiment, the shaft portion 56b is in a columnar shape. The shaft portion 56b extends from the connection portion 56a. The shaft portion 56b is inserted through the through hole 52h of the negative electrode current collector terminal 52.

[0021] The first member 56 is made of, for example, a first metal. The first metal may be, for example, aluminum, an aluminum alloy (an alloy containing at least 70% by mass of aluminum among all components; the same shall apply hereinafter), copper, or a copper alloy. Although not particularly limited, the first metal and a second metal described later may be the same or different from each other. When the first metal and the second metal are different metals from each other, the first metal is preferably copper or a copper alloy.

[0022] The second member 58 is, for example, a portion where the bus bar 14 is welded. In this embodiment, the second member 58 is in a flat plate shape. The second member 58 is arranged along the outer surface 32u of the sealing plate 32. As shown in FIG. 2, the second member 58 has a non-through recess 582 on a first surface 581 in the thickness direction. The connecting portion 56a of the first member 56 is accommodated in the recess 582, and its peripheral portion is caulked to the inner wall surface of the recess 582. Here, "the peripheral portion of the connecting portion 56a of the first member 56 is caulked to the inner wall surface of the recess 582" means, for example, a state where the first member 56 is fixed to the second member 58 by pressure welding the peripheral portion of the connecting portion 56a of the first member 56 to the inner wall surface of the insertion hole 582. The second surface 584 in the thickness direction of the second member 58 is a flat surface here. In this embodiment, the bus bar 14 is welded to the second surface 584.

[0023] In this embodiment, the second member 58 has a space 58S between it and the first member 56. In the space 58S, it is a space where gas can stay here. In the form shown in FIG. 2, a space 58S is formed between the inner wall of the recess 58 and the connecting portion 56a of the first member 56 accommodated in the recess 58. For example, if the upper end surface of the connecting portion 56a is recessed, a space 58S may be formed between the connecting portion 56a and the inner wall surface of the recess 58.

[0024] As shown in Figure 2, the second member 58 has a ventilation hole 58h. The ventilation hole 58h is, for example, a through hole that connects the space 58S to the outside air. Here, the ventilation hole 58h is provided in a location that can communicate with the through hole 14h of the bus bar 14, which will be described later. The size, planar shape, etc., of the ventilation hole 58h are not particularly limited and can be set as appropriate, as long as the effects of the technology disclosed herein can be realized.

[0025] The second member 58 is made of, for example, a second metal. The second metal may be, for example, aluminum, an aluminum alloy, copper, or a copper-based alloy. If the first metal and the second metal are different metals, the second metal is preferably aluminum or an aluminum alloy.

[0026] The positive terminal 40 may have a structure similar to that of the negative terminal 50, for example. For this reason, a description of the structure of the positive terminal 40 is omitted here. The positive terminal 40 is preferably made of aluminum or an aluminum alloy as a whole.

[0027] As shown in Figure 2, the energy storage device 12 is equipped with insulating members 60. The insulating member 60 is, for example, an insulating member that insulates between the negative electrode external terminal 54 and the sealing plate 32, and between the sealing plate 32 and the negative electrode current collector terminal 52. In this embodiment, the insulating member 60 is positioned between the negative electrode external terminal 54 and the outer surface 32u of the sealing plate 32, between the negative electrode external terminal 54 and the second through hole 322, and between the inner surface 32d of the sealing plate 32 and the negative electrode current collector terminal 52. The material constituting the insulating member 60 can be any material used as an insulating member in this type of energy storage device (e.g., a lithium-ion secondary battery) without particular limitations. The insulating member 60 may be integrally molded to achieve the above-described function, or it may be formed by combining multiple parts. Although not shown in the figure, the energy storage device 12 is also equipped with a similar insulating member on the positive electrode side.

[0028] The busbar 14 is, for example, a component that electrically connects two adjacent energy storage devices 12. In this embodiment, the busbar 14 is flat. As shown in Figure 2, the busbar 14 has through holes 14h. The size, planar shape, etc., of the ventilation holes 58h are not particularly limited and can be set as appropriate, as long as the effects of the disclosed technology can be realized. The busbar 14 is made of, for example, aluminum or an aluminum alloy.

[0029] As shown in Figure 1, the busbar 14 spans two adjacent energy storage devices 12 in the array direction P. In this embodiment, the busbar 14 spans the positive terminal 40 of one of the two adjacent energy storage devices 12 in the array direction P and the negative terminal 50 of the other energy storage device 12.

[0030] Figure 3 is a view of the busbar 14 from the upper surface 141 side. As shown in Figures 2 and 3, the busbar 14 is placed on the negative electrode external terminal 54. In the configuration shown in Figures 2 and 3, the busbar 14 is placed on the second surface 584 of the second member 58. In this embodiment, the through hole 14h of the busbar 14 and the ventilation hole 58h of the second member 58 overlap. This allows the space 58S to communicate with the outside air.

[0031] In this embodiment, the busbar 14 is welded to the positive terminal 40 of one of two adjacent energy storage devices 12 in the array direction P, and to the negative terminal 50 of the other energy storage device 12. In the configurations shown in Figures 2 and 3, the busbar 14 is welded to the negative external terminal 54 (welded portion 14a). The busbar 14 is welded to the second member 58. Means for welding the electrode terminals and the busbar 14 include, for example, laser welding and resistance welding, and laser welding is preferred from the viewpoint of improving welding strength.

[0032] As shown in Figure 3, the second member 58 and the busbar 14 are welded around the ventilation hole 58h. In the configuration shown in Figure 3, when the first surface 30a is viewed from the front, welds 14a are provided on the left (L) and right (R) sides of the ventilation hole 58h. The location of the welds 14a can be anywhere around the ventilation hole 58h. In other embodiments, the welds 14a may be provided on the upper (U) and lower (D) sides of the ventilation hole 58h. Alternatively, the welds 14a may be provided in a ring shape surrounding the ventilation hole 58h.

[0033] As shown in Figure 1, in the energy storage module 100, multiple energy storage devices 12 are constrained in the arrangement direction P. The energy storage module 100 comprises a spacer 11 and a pair of end plates 17. The spacer 11 is positioned between adjacent energy storage devices 12 in the arrangement direction P. The end plates 17 are positioned at both ends of the multiple energy storage devices 12 arranged in the arrangement direction P, constraining the multiple energy storage devices 12. The end plates 17 are bridged by metal restraint bands 18. The ends of the restraint bands 18 are fixed by screws 19.

[0034] As described above, the metal member (in this case, the negative electrode terminal 50) comprises a first metal member 56 and a second metal member 58. The second member 58 is superimposed on the first member 56. The second member 58 has a space 58S between it and the first member 56 in which gas can be retained. The second member 58 has a ventilation hole 58h that connects the space 58S to the outside air.

[0035] In other words, in the metal component (in this case, the negative electrode terminal 50), there is a space 58S between the superimposed first component 56 and the second component 58. Here, the second component 58 has a ventilation hole 58h, which allows the space 58S to communicate with the outside air. For this reason, for example, when welding another metal component to a metal component, the gas (e.g., air) in the space 58S that has expanded due to the applied heat is discharged into the outside air through the ventilation hole 58h. This reduces the internal pressure of the space 58S, thereby reducing the risk of molten metal (e.g., molten second component 58) scattering into the surroundings.

[0036] The second member 58 may have a non-penetrating recess 582 in the first surface 581. A part of the first member 56 (here, a connecting portion 56a) may be housed inside the recess 582. A space 58S is created between the inner wall of the recess 582 and the part of the first member 56 housed inside the recess 582. In the space 58S created by the inner wall of the recess 582 and the part of the first member 56 housed therein (here, the connecting portion 56a), the internal pressure tends to increase due to gas expansion. Therefore, by providing a ventilation hole 58h that connects this space 58S to the outside air, the effects of the technology disclosed herein can be better realized.

[0037] The metal constituting the first member 56 and the metal constituting the second member 58 may be different from each other. This allows the first member 56, which is a connecting member to the negative electrode current collection terminal 52 that collects current from the negative electrode of the electrode body, and the second member 58, which is a connecting member to the busbar 14, to be made of different metals. As a result, the conductivity between the electrode body, the negative electrode terminal 50, and the busbar 14 can be improved.

[0038] The metal member (in this case, the negative electrode terminal 50) may further comprise a third metal member (in this case, a busbar 14). The third member may be placed on the surface of the second member 58 and may also be welded to the second member 58. As described above, since the second member 58 is provided with ventilation holes 58h, the internal pressure of the space 58S can be reduced. Therefore, when welding the third member to the second member 58, the risk of molten metal (for example, molten second member 58) scattering into the surroundings can be reduced.

[0039] The second member 58 and the third member (in this case, the busbar 14) may be welded around the vent hole 58h. This allows heat to be applied around the vent hole 58h, which serves as the gas outlet from the space 58S, during welding. As a result, gas can be discharged from the space 58S more efficiently.

[0040] The third member (in this case, the bus bar 14) may have a through hole 14h. The ventilation hole 58h of the second member 58 and the through hole 14h of the third member may be in communication. By having the through hole 14h and the ventilation hole 58h in communication, gas can be discharged from the space 58S more efficiently.

[0041] As described above, the energy storage device 12 is equipped with a negative electrode terminal 50. By providing the negative electrode terminal 50, when the busbar 14 is welded to the negative electrode terminal 50, gas can be efficiently discharged from the space 58S into the outside air. Therefore, when the busbar 14 is welded to the energy storage device 12, the risk of molten metal (for example, molten second member 58) scattering into the surroundings can be reduced. This makes it possible to construct an energy storage module 100 with improved welding quality between the electrode terminal and the busbar 14.

[0042] The energy storage module 100 includes a negative electrode terminal 50 comprising a first member 56 and a second member 58 as electrode terminals. The busbar 14 includes a third member which is welded to the metal member comprising the first member 56 and the second member 58. Therefore, when the busbar 14 is welded to the energy storage device 12, the risk of molten metal (for example, molten second member 58) scattering into the surroundings can be reduced. This improves the welding quality between the electrode terminal and the busbar 14 in the energy storage module 100.

[0043] The technologies disclosed herein may include the technologies described in the following sections. Section 1: A first metal component, A second metal member is superimposed on the first member, A metal member comprising, The second member is, The first member has a space between it and the gas that can accumulate, A metal member having a ventilation hole that connects the space with the outside air. Section 2: The second member has a non-penetrating recess on its first surface, A part of the first member is housed inside the recess. The metal member according to item 1, wherein the space is created between the inner wall of the recess and a part of the first member housed in the recess. Section 3: The metal member according to claim 1 or 2, wherein the metal constituting the first member and the metal constituting the second member are different from each other. Section 4: Furthermore, it is equipped with a third metal component, The metal member according to any one of claims 1 to 3, wherein the third member is placed on the surface of the second member and is welded to the second member. Section 5: The metal member according to item 4, wherein the second member and the third member are welded around the ventilation hole. Item 6: The third member has a through hole, The metal member according to item 4 or 5, wherein the ventilation hole of the second member and the through hole of the third member are in communication with each other. Section 7: An electrode terminal used in an energy storage device, comprising a metal member as described in any one of items 1 to 3. Section 8: A power storage module comprising electrode terminals and busbars, The metal member is provided as described in any one of items 4 to 6. The electrode terminal includes the first member and the second member, The busbar is a power storage module that includes the third member.

[0044] The embodiments of the technology disclosed herein have been described above, but these are merely illustrative and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes to the specific examples illustrated above. [Explanation of Symbols]

[0045] 100 Energy Storage Modules 12 Energy Storage Devices 14 Bus Bar 14h through hole 30 cases 40 Positive terminal 50 Negative terminal 54 Negative external terminal 56 First Member 58 Second Member 581 Page 1 582 recess 58h ventilation holes 58S space 60 Insulating material

Claims

1. A first metal component, A second metal member is superimposed on the first member, A metal member comprising, The second member is, The first member has a space between it and the gas that can accumulate, A metal member having a ventilation hole that connects the space with the outside air.

2. The second member has a non-penetrating recess on its first surface, A part of the first member is housed inside the recess. The metal member according to claim 1, wherein the space is created between the inner wall of the recess and a part of the first member housed in the recess.

3. The metal member according to claim 1, wherein the metal constituting the first member and the metal constituting the second member are different from each other.

4. Furthermore, it is equipped with a third metal component, The metal member according to claim 1, wherein the third member is placed on the surface of the second member and is welded to the second member.

5. The metal member according to claim 4, wherein the second member and the third member are welded around the ventilation hole.

6. The third member has a through hole, The metal member according to claim 4, wherein the ventilation hole of the second member and the through hole of the third member are in communication with each other.

7. An electrode terminal used in an energy storage device, comprising a metal member as described in any one of claims 1 to 3.

8. A power storage module comprising electrode terminals and busbars, The metal member comprises the metal member described in any one of claims 4 to 6. The electrode terminal includes the first member and the second member, The busbar is a power storage module that includes the third member.

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