WO2017033985A1

WO2017033985A1 - Current cut-off device and manufacturing method therefor

Info

Publication number: WO2017033985A1
Application number: PCT/JP2016/074709
Authority: WO
Inventors: 貴之弘瀬; 幹也栗田; 竜二大井手; 俊昭岩; 小川　義博; 淳光安; 騎慎秋吉
Original assignee: 株式会社豊田自動織機; イーグル工業株式会社
Priority date: 2015-08-27
Filing date: 2016-08-24
Publication date: 2017-03-02
Also published as: JP2018170069A

Abstract

A current cut-off device 10 is housed within a case 1 and is provided with a conducting plate 20 and a first deformation plate 30. The conducting plate 20 is electrically connected to an electrode assembly 3. The first deformation plate 30 is electrically connected to a terminal 7 and is disposed on one side of the conducting plate 20. The conducting plate 20 includes a contact part 22 which contacts the first deformation plate 30 when the electrode assembly 3 and the terminal 7 are in an electrical conducting state. The first deformation plate 30 is electrically connected when the electrode assembly 3 and the terminal 7 are in an electrical conducting state, but is not electrically connected to the conducting plate 20 when the electrode assembly 3 and the terminal 7 are in a non-conducting state. A weld part 40 is provided to the contact part 22 at the other side of the conducting plate 20. At the position at which the weld part 40 is disposed, the conducting plate 20 and the first deformation plate 30 are connected, and the thickness of the conducting plate 20 is no greater than the thickness of the first deformation plate 30.

Description

Current interrupting device and manufacturing method thereof

This application claims priority based on Japanese Patent Application No. 2015-168269 filed on August 27, 2015. The entire contents of that application are incorporated herein by reference. The technology disclosed in the present specification relates to a current interrupting device and a manufacturing method thereof.

There is known a current interrupting device that is housed in a case and interrupts the energization path when the pressure in the case increases. For example, a current interrupting device disclosed in Japanese Patent Application Laid-Open No. 2013-215862 has an energizing plate and a deforming plate. The energization plate is electrically connected to the electrode assembly in the case. The deformation plate electrically connects the terminal fixed to the mounting hole on the wall surface of the case and the current-carrying plate. The deformable plate is located above the energizing plate and below the terminals. When the pressure in the case increases, the deformation plate is deformed, and the electrical connection between the terminal and the electrode assembly is interrupted.

A terminal disclosed in Japanese Patent Laid-Open No. 2013-215862 is formed with a through hole extending in the vertical direction, and the inside and outside of the case communicate with each other through the through hole. In the conventional technique, when welding the deformable plate and the current-carrying plate, a laser beam is irradiated from the outside of the case toward the deformable plate through the through hole of the terminal in a state where they are in contact with each other. In this configuration, there is a problem that welding is difficult because another member is interposed between the laser beam irradiation port and the welded portion of the deformation plate and the current plate. This specification discloses the technique which can weld a deformation | transformation board and an electricity supply board more easily.

The current interrupt device disclosed in this specification is housed in a case. The current interrupting device electrically connects the electrode assembly housed in the case to the positive or negative terminal fixed to the mounting hole on the wall surface of the case, and the internal pressure of the case rises above a predetermined value. The current-carrying path for electrically connecting the electrode assembly and the terminal is cut off. The current interrupt device includes an energization plate and a first deformation plate. The energization plate is electrically connected to the electrode assembly. The first deforming plate is electrically connected to the terminal and is disposed on one side of the energizing plate so as to face the energizing plate. The energization plate has a contact portion that is in contact with the first deformation plate in a state where the electrode assembly and the terminal are electrically connected. The first deformation plate is electrically connected in a state where it is in contact with the contact portion of the current-carrying plate when the electrode assembly and the terminal are in a conductive state, and the electrode assembly and the terminal are in a non-conductive state. Then, it is electrically disconnected from the energizing plate while being separated from the energizing plate. The contact portion of the energization plate is in surface contact with the first deformation plate. The contact surface of the contact portion with the first deformation plate is flat, and the contact surface of the first deformation plate with the contact portion is flat. A welding portion is provided at the contact portion on the surface on the other side of the energization plate. At the position where the welded portion is provided, the energization plate and the first deformation plate are joined, and the thickness of the energization plate is equal to or less than the thickness of the first deformation plate.

When two plate members are joined by welding, if the thickness of one plate member on which the weld is provided (that is, the plate member directly irradiated with the laser beam) is larger than the thickness of the other plate member, the heat of the laser beam is It may diffuse inside the plate material and the two plate materials may not be properly welded. In said electric current interruption apparatus, the thickness of an electricity supply board is below the thickness of a 1st deformation board in the position which provides a welding part. For this reason, even when the laser beam is irradiated from the other side of the energization plate toward the energization plate, the heat of the laser beam becomes difficult to diffuse inside the energization plate, and the energization plate and the first deformation plate are joined. Is possible. As a result, it is possible to irradiate the laser beam with no other member interposed between the current-carrying plate and the welded portion of the first deformation plate and the laser beam irradiation port. Can be welded more easily. Further, the contact surfaces of the contact portion of the energization plate and the first deformation plate are flat with each other. For this reason, an electricity supply board and a 1st deformation board can be welded more accurately. When the welded part is raised from the surface on the other side of the current plate before welding, the “thickness of the current plate at the position where the welded part is provided” means the height of the raised part of the welded part. It means the thickness of the current-carrying plate excluded. That is, it means the thickness of the current plate before welding. Therefore, even if the thickness of the current-carrying plate is greater than the thickness of the first deformation plate due to the rise of the welded portion after welding, if the thickness of the current-carrying plate before welding is equal to or less than the thickness of the first deformation plate, At the position where the portion is provided, the thickness of the current-carrying plate is less than or equal to the thickness of the first deformable plate.

Also, the present specification discloses a novel manufacturing method of the current interrupting device. The manufacturing method of this electric current interruption apparatus is equipped with a terminal fixing process, a 1st deformation board welding process, an electricity supply board arrangement | positioning process, and an electricity supply board welding process. In the terminal fixing step, the terminal is fixed in a mounting hole provided in the wall surface of the case. In the first deformation plate welding step, the surface on one side of the first deformation plate is welded to the surface on the other side of the terminal. In the energizing plate arranging step, the energizing plate is arranged so as to contact at least partly with the surface on the other side of the first deforming plate after the terminal fixing step and the first deforming plate welding step. In the energizing plate welding step, after the energizing plate placement step, the energizing plate and the first deformation plate are welded by irradiating the energizing plate with the laser beam from the other side to the other side of the energizing plate. Before the current plate welding step is performed, the thickness of the current plate at the position where the laser beam is irradiated is equal to or less than the thickness of the first deformation plate at the position where the current plate is joined by welding. According to this manufacturing method, the energizing plate and the first deformable plate can be joined without going through the terminal through-hole, so that there are other members between the energized plate and the welded portion of the first deformable plate and the laser beam irradiation port. The laser beam can be irradiated without being interposed, and the energization plate and the first deformation plate can be more easily welded.

Also, the present specification discloses a power storage device including the above-described current interrupt device. The power storage device may be a secondary battery. According to this configuration, current can appropriately flow between the terminals.

Details of the technology disclosed in the present specification and further improvements will be described in detail in embodiments and examples for carrying out the invention.

1 is a longitudinal sectional view of a power storage device according to Embodiment 1. FIG. The elements on larger scale of the dashed-two dotted line part 200 of FIG. The elements on larger scale of the part which the electricity supply board and the 1st deformation | transformation board are contact | abutting. The bottom view of a 1st deformation board. The manufacturing method of the electric current interruption apparatus of Example 1 is shown (terminal fixing process, 1st deformation board welding process). The manufacturing method of the electric current interruption apparatus of Example 1 is shown (electricity plate arrangement | positioning process, electric current plate welding process). It is the elements on larger scale near the negative electrode terminal of the electrical storage apparatus of Example 2, and shows the state which the electric current interruption apparatus does not operate | move. It is the elements on larger scale near the negative electrode terminal of the electrical storage apparatus of Example 2, and shows the state which the electric current interruption apparatus operated.

The main features of the embodiment described below are listed. The technical elements described below are independent technical elements and exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Absent.

(Feature 1) In the current interrupt device disclosed in the present specification, the welded portion may be disposed at a part of the contact portion of the energizing plate. The thickness of the energization plate may be equal to or less than the thickness of the first deformation plate in the entire area of the contact portion. According to this configuration, it is not necessary to strictly control the position where the energization plate is irradiated with the laser beam, and the energization plate and the first deformation plate can be joined relatively easily.

(Characteristic 2) In the current interrupting device disclosed in the present specification, a groove portion that goes around the outer periphery of the welded portion may be provided on the other surface of the energization plate. The thickness of the energizing plate in the portion where the groove is provided may be smaller than the thickness of the energizing plate in the portion where the groove is not provided. According to this configuration, the mechanical strength of the energizing plate in the portion where the groove is provided is lower than the mechanical strength of the energizing plate in the portion where the groove is not provided. For this reason, the timing at which the first deformable plate changes from the conductive state to the non-conductive state can be controlled by adjusting the thickness of the conductive plate in the portion where the groove is provided.

(Characteristic 3) In the current interrupting device disclosed in this specification, when the energization plate is viewed in plan, the groove may have a circular shape with a radius r. When the thickness of the current-carrying plate in the portion where the groove is provided is t and the area of the contact part of the current-carrying plate is A, the following relational expression:

May be established. According to this configuration, in the energization path, the resistance value of the energization plate in the portion where the groove is provided can be made higher than the resistance value of the energization plate in the contact portion. If the resistance value of the current-carrying plate in the portion where the groove is provided can be made higher than the resistance value of the current-carrying plate in the contact portion, the maximum resistance value of the current-carrying path is determined by the resistance value of the current-carrying plate in the contact portion There is no. Therefore, the contact portion can be designed without affecting the maximum value of the resistance of the energization path.

(Characteristic 4) The current interrupting device disclosed in the present specification further includes a second deformation plate that is disposed on the other side with respect to the energization plate and provided with a protrusion protruding toward the energization plate. It may be. The second deformable plate includes a first state in which the protrusion is positioned at the first position and the energizing plate and the first deformable plate are in contact with each other when the electrode assembly and the terminal are electrically connected; When the terminal is in a non-conducting state, the protrusion may move from the first position to the second position on the energizing plate side to switch to the second state in which the energizing plate and the first deforming plate are separated from each other.

Hereinafter, the power storage device 100 according to the first embodiment will be described with reference to FIGS. 1 to 4. The power storage device 100 is a lithium ion secondary battery that is a type of secondary battery. As shown in FIG. 1, the power storage device 100 includes a case 1, an electrode assembly 3 accommodated in the case 1, and

terminals

5 and 7 fixed to the case 1. The electrode assembly 3 and the

terminals

5 and 7 are electrically connected. The power storage device 100 also includes a current interrupt device 10 disposed between the electrode assembly 3 and the terminal 7. The inside of the case 1 is injected with an electrolytic solution, and the electrode assembly 3 is immersed in the electrolytic solution. In FIG. 4, the groove portion 20 a and the contact portion 22 (described later) of the energizing plate 20 are shown enlarged to make the drawing easier to see.

Case 1 is made of metal and is a substantially rectangular parallelepiped box-shaped member. The case 1 includes a main body 111 and a lid portion 112 fixed to the main body 111. The lid part 112 covers the upper part of the main body 111. Mounting

holes

11 and 13 are formed in the lid portion 112 of the case 1. The terminal 5 is fixed to the mounting hole 11 and communicates with the inside and outside of the case 1. The terminal 7 is fixed to the mounting hole 13 and communicates with the inside and outside of the case 1. The lid 112 corresponds to an example of a “case wall surface”.

The electrode assembly 3 includes a positive electrode sheet, a negative electrode sheet, and a separator disposed between the positive electrode sheet and the negative electrode sheet. The electrode assembly 3 is configured by laminating a plurality of positive electrode sheets, a plurality of negative electrode sheets, and a plurality of separators. The positive electrode sheet and the negative electrode sheet include a current collecting member and an active material layer formed on the current collecting member. As the current collecting member, one used for the positive electrode sheet is, for example, an aluminum foil, and one used for the negative electrode sheet is, for example, a copper foil. The electrode assembly 3 includes a positive current collecting tab 41 and a negative current collecting tab 42. The positive electrode current collecting tab 41 is formed on the upper end portion of the positive electrode sheet. The negative electrode current collecting tab 42 is formed on the upper end portion of the negative electrode sheet. The positive electrode current collecting tab 41 and the negative electrode current collecting tab 42 protrude above the electrode assembly 3. The positive electrode current collecting tab 41 is fixed to the positive electrode lead 43. The negative electrode current collecting tab 42 is fixed to the negative electrode lead 44.

The positive electrode lead 43 is connected to the positive electrode current collecting tab 41 and the terminal 5. The positive electrode current collecting tab 41 and the terminal 5 are electrically connected via the positive electrode lead 43. An insulating member 72 is disposed between the positive electrode lead 43 and the case 1. The insulating member 72 insulates the positive electrode lead 43 from the lid portion 112 of the case 1.

The negative electrode lead 44 is connected to the negative electrode current collecting tab 42 and the connection terminal 46. The connection terminal 46 is electrically connected to the terminal 7 via the current interrupt device 10. Therefore, the negative electrode current collecting tab 42 and the terminal 7 are electrically connected via the negative electrode lead 44, the connection terminal 46, and the current interrupt device 10. Thereby, an energization path for connecting the electrode assembly 3 and the terminal 7 is formed. The current interrupt device 10 can interrupt this energization path. The configuration of the current interrupt device 10 will be described later. An insulating member 73 is disposed between the negative electrode lead 44 and the case 1. The insulating member 73 insulates the negative electrode lead 44 from the case 1.

Resin gaskets

62 and 63 are disposed on the upper surface of the lid portion 112. The gasket 62 is fixed to the terminal 5. A flat plate-like external terminal 60 is disposed on the upper surface of the gasket 62. A through hole 60 a is formed in the external terminal 60. The through hole 60a is larger in size on the lower surface side than on the upper surface side. The gasket 62 insulates the lid portion 112 from the external terminal 60. The bolt 64 passes through the through hole 60a. Specifically, the head of the bolt 64 is accommodated in the through hole 60a. Further, the shaft portion of the bolt 64 protrudes above the external terminal 60 through the through hole 60a. The terminal 5, the external terminal 60, and the bolt 64 are electrically connected to each other and constitute a positive terminal. The gasket 63 is fixed to the terminal 7. A flat plate-like external terminal 61 is disposed on the upper surface of the gasket 63. A through hole similar to the through hole 60a of the external terminal 60 is formed in the external terminal 61. The head of the bolt 65 is accommodated in the through hole, and the shaft portion of the bolt 65 passes through the through hole and the external terminal 61 is passed through. Projecting upward. The configuration of the gasket 63, the external terminal 61, and the bolt 65 is the same as the configuration of the gasket 62, the external terminal 60, and the bolt 64 described above. The terminal 7, the external terminal 61, and the bolt 65 are electrically connected to each other and constitute a negative terminal.

Here, the terminal 7 will be described with reference to FIG. As shown in FIG. 2, the terminal 7 is caulked and fixed to the case 1. The terminal 7 includes a cylindrical portion 14, a base portion 15, and a fixing portion 16. The cylindrical portion 14 is inserted through the mounting hole 13. A through hole 14 a is formed in the cylindrical portion 14. The base portion 15 is formed in an annular shape. The base portion 15 is located at the lower end portion of the cylindrical portion 14 and is disposed inside the case 1. A recess 15 a is formed in the base portion 15. The recess 15a communicates with the through hole 14a, and the interior of the recess 15a is maintained at atmospheric pressure. The fixed portion 16 is formed in an annular shape. The fixed portion 16 is located at the upper end portion of the cylindrical portion 14 and is disposed outside the case 1. The terminal 7 is fixed to the lid portion 112 of the case 1 by a fixing portion 16.

A seal member 19 is disposed between the lid portion 112 of the case 1 and the terminal 7. The seal member 19 has an annular shape and goes around the cylindrical portion 14 of the terminal 7. The seal member 19 is in contact with the lower surface of the lid portion 112 of the case 1 and the inner peripheral surface of the mounting hole 13, and the base portion 15 and the cylindrical portion 14 of the terminal 7, thereby sealing the inside and outside of the case 1. Yes. The seal member 19 is made of a material having insulating properties and electrolyte resistance (perfluoroalkoxyalkane (PFA) in this embodiment). The lid portion 112 and the terminal 7 are insulated by the seal member 19. The material of the seal member 19 is not limited to this, and may be, for example, ethylene-propylene rubber (EPM).

Next, the current interrupting device 10 will be described with reference to FIGS. As shown in FIG. 2, the current interrupt device 10 includes a deformable plate 30 and a current plate 20. The deformable plate 30 is a circular conductive diaphragm convex downward, and is formed of copper or a copper alloy in this embodiment. The deformation plate 30 is disposed above the energizing plate 20 so as to face the energizing plate 20. The deformation plate 30 has a substantially constant thickness t1 (see FIG. 3), and has a central portion 32 on the radially inner side and an outer peripheral portion 31 on the radially outer side. The lower surface of the central portion 32 is flat and is substantially parallel to the lid portion 112 of the case 1. The central portion 32 is in surface contact (surface contact) with a contact portion 22 (described later) of the energization plate 20. The outer peripheral portion 31 is connected to the outer peripheral portion of the base portion 15 of the terminal 7. That is, the deformation plate 30 is electrically connected to the terminal 7. The recess 15 a of the base portion 15 is covered with the deformation plate 30. Since the inside of the recess 15 a is maintained at atmospheric pressure, atmospheric pressure acts on the upper surface of the deformation plate 30. The deformation plate 30 corresponds to an example of “first deformation plate”, and the upper side of the energization plate 20 corresponds to an example of “one side of the energization plate”.

The current plate 20 is a conductive metal member, and is formed of copper or a copper alloy in this embodiment. The energization plate 20 is formed in a circular shape having a larger diameter than the deformation plate 30 in plan view, and is disposed below the deformation plate 30. The upper surface of the energization plate 20 is flat and substantially parallel to the lid portion 112 of the case 1. A connection terminal 46 is connected to the energization plate 20. That is, the energization plate 20 is electrically connected to the electrode assembly 3 through the connection terminal 46 and the negative electrode lead 44. A circular groove 20a is formed on the lower surface of the energizing plate 20 in a bottom view (see FIG. 4). As shown in FIGS. 2 and 3, when the groove 20 a is cut in the thickness direction of the current-carrying plate 20, the cross section has a triangular shape having an apex v above. The radius of the groove 20a (that is, the distance from the center O of the groove 20a to the vertex v) when the energizing plate 20 is viewed from the bottom is r (see FIG. 4). As shown in FIG. 3, the energizing plate 20 has a substantially constant thickness t4 in the circumferential direction at the apex v of the groove 20a. The energizing plate 20 is divided into a contact portion 22 positioned radially inward of the vertex v and an outer peripheral portion 21 positioned radially outward of the vertex v by the groove 20a. As described above, the lower surface of the central portion 32 of the deformation plate 30 and the upper surface of the contact portion 22 of the energizing plate 20 are both substantially parallel to the lid portion 112 of the case 1 and are both flat. For this reason, as shown by a thick line in FIG. 3, the upper surface of the contact portion 22 is in surface contact (surface contact) with the lower surface of the central portion 32 of the deformation plate 30 in the entire contact portion 22. The contact area is A. When the contact portion 22 is in surface contact with the central portion 32 of the deformable plate 30, the deformable plate 30 is electrically connected to the energizing plate 20, and the electrode assembly 3 and the terminal 7 are electrically connected (see FIG. 1). Between the radius r of the groove 20a, the thickness t4 of the current-carrying plate 20 in the groove 20a, and the area A of the contact portion 22, the following relational expression:

Is established. The current interrupting device 10 has an energization path that connects the connection terminal 46, the energization plate 20, the deformation plate 30, and the terminal 7 in series in this order. According to the above relational expression, the resistance value of the energizing plate 20 in the groove 20 a can be made higher than the resistance value of the energizing plate 20 in the contact portion 22. When the resistance value of the energizing plate 20 in the portion where the groove 20 a is provided can be made higher than the resistance value of the energizing plate 20 in the contact portion 22, the maximum resistance of the energization path becomes the energizing plate 20 in the contact portion 22. It is no longer determined by the resistance value. Therefore, it is possible to design the contact portion 22 without affecting the maximum value of the resistance of the energization path. The flatness of the lower surface of the central portion 32 and the upper surface of the contact portion 22 (geometric tolerance defined in JIS) can be appropriately set in consideration of the contact resistance and welding quality of both. For example, the flatness of the lower surface of the central portion 32 and the upper surface of the contact portion 22 can be 0.0 to 0.2 mm, and more preferably 0.0 to 0.05 mm. By maintaining the flatness within such a range, the contact resistance and welding quality of both can be suitably secured.

As shown in FIG. 3, the contact portion 22 has a substantially constant thickness t2, and the outer peripheral portion 21 has a substantially constant thickness t3. The thickness t2 of the contact portion 22 is smaller than the thickness t3 of the outer peripheral portion 21 and smaller than the thickness t1 of the deformable plate 30. The thickness t3 of the outer peripheral portion 21 is larger than the thickness t1 of the deformation plate 30. A plurality of weld beads 40 are formed on the lower surface of the current-carrying plate 20 at the contact portion 22. That is, at the position where the weld bead 40 is formed, the thickness t <b> 2 of the energization plate 20 is smaller than the thickness t <b> 1 of the deformation plate 30. In addition, the thickness t4 of the energizing plate 20 in the portion where the groove 20a is formed is smaller than the thickness (ie, the thickness t2 or t3) of the energizing plate 20 in the portion where the groove 20a is not formed. According to this configuration, the mechanical strength of the current-carrying plate 20 in the portion where the groove portion 20a is formed is the mechanical strength of the current-carrying plate 20 (that is, the contact portion 22 and the outer peripheral portion 21) in the portion where the groove portion 20a is not formed. Lower than. For this reason, the timing at which the deformable plate 30 changes from the conductive state to the nonconductive state can be controlled by adjusting the thickness t4 of the conductive plate 20 in the groove 20a. The lower surface of the energizing plate 20 corresponds to an example of “the surface on the other side of the energizing plate”, and the weld bead 40 corresponds to an example of a “welded portion”.

As shown in FIG. 2, the energization plate 20 is formed with a vent hole 20b, and the space 50 between the deformation plate 30 and the energization plate 20 communicates with the space in the case 1 through the vent hole 20b. Yes. In addition, a plurality of through holes 20c are formed in the energizing plate 20 on the radially outer side than the air holes 20b. A heat caulking boss 79 of a holder 80 described later is inserted into the through hole 20c. The energization plate 20 is fixed to the holder 80 by subjecting the heat caulking boss 79 to heat caulking. An annular insulating member 75 is disposed between the outer peripheral portion 31 of the deformation plate 30 and the outer peripheral portion 21 of the energizing plate 20.

As shown in FIG. 2, the holder 80 accommodates and holds the base portion 15 of the terminal 7, the deformation plate 30, and the insulating member 75 therein. The holder 80 is annular, and the terminal 7 is inserted through the center thereof. The holder 80 is formed of a material having insulation properties and resistance to electrolytic solution (in this embodiment, polyphenylene sulfide (PPS)). The material of the holder 80 is not limited to the above, and may be, for example, PFA, polytetrafluoroethylene (PTFE), polypropylene (PP), or the like.

The holder 80 has an upper end portion 77 and a side portion 78. The upper end portion 77 is disposed between the lid portion 112 of the case 1 and the base portion 15 of the terminal 7. The upper end portion 77 is in contact with the lower surface of the lid portion 112 and the upper surface of the base portion 15, and serves as a spacer that determines the distance between the lid portion 112 and the base portion 15. The lid portion 112 and the base portion 15 are insulated by the upper end portion 77. The side portion 78 extends downward from the outer peripheral edge of the upper end portion 77. The side portion 78 accommodates the base portion 15, the deformation plate 30, and the insulating member 75 therein. A lower surface 78 a of the side portion 78 is flat and substantially parallel to the lid portion 112 of the case 1. A plurality of heat caulking bosses 79 are formed on the lower surface 78 a of the side portion 78. The heat caulking boss 79 is formed at a position corresponding to the through hole 20c of the energizing plate 20, and is inserted into the through hole 20c. The heat caulking boss 79 is in close contact with the inner peripheral surface of the through hole 20c by the heat caulking process, and the diameter of the lower end thereof is larger than the diameter of the through hole 20c. As a result, the energizing plate 20 is fixed to the holder 80 in a state where the upper surface of the energizing plate 20 is in contact with the lower surface 78 a of the side portion 78.

As is clear from the above description, the current interrupt device 10 has an energization path that connects the connection terminal 46, the energization plate 20, the deformation plate 30, and the terminal 7 in series. For this reason, the electrode assembly 3 and the terminal 7 are electrically connected via the energization path of the current interrupt device 10.

Here, the interruption operation of the current interruption device 10 will be described. In the power storage device 100 described above, the deformable plate 30 is electrically connected to the energizing plate 20 while being in contact with the abutting portion 22 of the energizing plate 20, and the terminal 5 and the terminal 7 are energized. It is possible to conduct. When the pressure in the case 1 increases due to overcharging of the power storage device 100 or the like, the pressure that acts on the lower surface of the deformation plate 30 through the vent hole 20b increases. On the other hand, atmospheric pressure acts on the upper surface of the deformation plate 30. For this reason, when the internal pressure of the case 1 rises and reaches a predetermined value, the deformable plate 30 is reversed and changes to a convex state upward. Then, the current-carrying plate 20 connected to the central portion 32 of the deformable plate 30 breaks starting from the mechanically fragile groove 20a, and the deformable plate 30 is separated from the remaining portion (that is, the outer peripheral portion 21) of the current-carrying plate 20. To do. As a result, the energization path connecting the energization plate 20 and the deformation plate 30 is interrupted, and the electrode assembly 3 and the terminal 7 are brought out of electrical conduction. At this time, the deformation plate 30 is insulated from the connection terminal 46, and the energization plate 20 is insulated from the terminal 7.

Next, a method for manufacturing the current interrupting device 10 will be described with reference to FIGS. Below, the description is abbreviate | omitted about the process same as the conventional manufacturing method.

(Terminal fixing process)
In this step, as shown in FIG. 5, the terminal 7 is fixed to the mounting hole 13 of the lid portion 112 of the case 1. In this embodiment, a rivet bolt is used as the terminal 7. First, the cylindrical portion of the terminal 7 (that is, the cylindrical portion constituted by the cylindrical portion 14 and the fixing portion 16 before caulking) is inserted through the opening of the upper end portion 77 of the holder 80, and the upper end portion 77 is moved. It is arranged on the upper surface of the base part 15. Next, the cylindrical portions (14, 16) are inserted into the seal member 19, and the seal member 19 is disposed on the upper surface of the base portion 15. On the other hand, the gasket 63 and the external terminal 61 are disposed on the upper surface of the lid portion 112 of the case 1. In this state, the cylindrical portion (14, 16) is inserted from the inside of the case 1 into the mounting hole 13, the opening of the gasket 63 and the opening of the external terminal 61. Thereafter, the upper end of the cylindrical portion (14, 16) is bent radially outward and pushed outward radially. As a result, the upper ends of the cylindrical portions (14, 16) abut on the upper surface of the external terminal 61, and the terminal 7 is caulked and fixed to the lid portion 112 of the case 1. When the terminal 7 is caulked and fixed to the lid portion 112 of the case 1, the upper end portion 77 of the holder 80, the seal member 19, the gasket 63, and the external terminal 61 are sandwiched between the terminal 7 and the lid portion 112 of the case 1. .

(First deformation plate welding process)
Next, the upper surface of the outer peripheral portion of the deformable plate 30 is in contact with the lower surface of the outer peripheral portion of the base portion 15 of the terminal 7, and is indicated by an arrow in FIG. 5 from below toward the lower surface of the outer peripheral portion of the deformable plate 30. Irradiate with a laser beam. The laser beam is irradiated so as to go around the lower surface of the outer peripheral portion of the deformation plate 30. Thereby, the deformation plate 30 is welded to the base portion 15 of the terminal 7 so as to cover the recess 15 a of the terminal 7.

(Electric plate placement process)
Subsequently, as shown in FIG. 6, an annular insulating member 75 is disposed on the lower surface of the outer peripheral portion of the deformable plate 30, and the heat caulking boss 79 of the holder 80 is inserted into the through hole 20 c of the energizing plate 20. The energization plate 20 is arranged so that the upper surface of the 20 contact portions 22 contacts the lower surface of the central portion 32 of the deformation plate 30. Next, the caulking process is applied to the heat caulking boss 79 to fix the energizing plate 20 to the holder 80, and the central portion 32 of the deformable plate 30 and the abutting portion 22 of the energizing plate 20 are brought into contact with each other.

(Electric plate welding process)
Next, a laser beam indicated by an arrow in FIG. 6 is irradiated from below the energizing plate 20 toward the lower surface of the contact portion 22 of the energizing plate 20. Laser beams are irradiated at equal intervals in the circumferential direction (see FIG. 4). Thereby, the current-carrying plate 20 and the deformation plate 30 are welded at the contact portion 22. As a result, a plurality of weld beads 40 are formed on the lower surface of the contact portion 22. By implementing the above-described steps, the current interrupt device 10 is manufactured.

The operation and effect of the current interrupt device 10 of the first embodiment will be described. In the current interrupt device 10, the thickness t2 of the energizing plate 20 at the position where the weld bead 40 is formed (that is, the position where the laser beam is irradiated) is the thickness t1 of the deforming plate 30 (that is, the energizing plate). 20 and the thickness of the deformable plate 30 at a position to be joined by welding. For this reason, even if the laser beam is irradiated from below the energizing plate 20 toward the lower surface of the energizing plate 20, the heat of the laser beam is difficult to diffuse inside the energizing plate 20, and the energizing plate 20 and the deformable plate 30 It becomes possible to join. As a result, the diameter of the through hole 14a of the terminal 7 can be reduced, and the amount of moisture entering the inside of the case 1 can be reduced. In the energizing plate welding process, the laser beam is irradiated from below the energizing plate 20. For this reason, welding can be performed in a state where no other member is interposed between the laser beam irradiation port and the welded portion, and the energizing plate 20 and the deformable plate 30 can be welded more easily. Furthermore, the relative position of the laser with respect to the lid 112 in the energization plate welding process is the same as the relative position of the laser with respect to the lid 112 in the first deformation plate welding process. Accordingly, it is not necessary to change the relative position of the laser with respect to the lid 112 in the current plate welding process, and workability is improved.

In particular, in Example 1, the contact portion 22 of the energization plate 20 is in surface contact (surface contact) with the central portion 32 of the deformation plate 30, and the thickness t <b> 2 of the energization plate 20 is in the entire contact portion 22. The deformation plate 30 is smaller than the thickness t1. For this reason, even if it irradiates any position of the contact part 22 with a laser beam, the electricity supply board 20 and the deformation | transformation board 30 can be joined appropriately. Therefore, as long as the contact portion 22 is irradiated with the laser beam, it is not necessary to strictly control the position where the laser beam is irradiated, and the energization plate 20 and the deformation plate 30 can be joined relatively easily. Further, the upper surface of the contact portion 22 of the energizing plate 20 and the lower surface of the central portion 32 of the deformation plate 30 are substantially parallel to each other and are both flat. That is, the contact portion 22 of the energization plate 30 and the central portion 32 of the deformation plate 30 are in close contact with each other over the entire contact portion 22. For this reason, even if it irradiates any position of the contact part 22 with a laser beam, the electricity supply board 20 and the deformation | transformation board 30 can be joined more reliably. Therefore, the current-carrying plate 20 and the deformation plate 30 can be joined with higher accuracy.

Next, the power storage device of Example 2 will be described with reference to FIGS. Hereinafter, only differences from the first embodiment will be described, and detailed description of the same configurations as those of the first embodiment will be omitted. A two-dot chain line portion 300 in FIG. 6 corresponds to the two-dot chain line portion 200 in FIG. 1. In this power storage device, the configuration of the current interrupt device 110 is different from the current interrupt device 10 of the first embodiment. The current interrupting device 110 includes a first deformation plate 130, an energization plate 120, and a second deformation plate 140. All of the first deformation plate 130, the energization plate 120, and the second deformation plate 140 are made of copper.

The first deformable plate 130 and the energizing plate 120 have substantially the same configuration as the deformable plate 30 and the energized plate 20 of the first embodiment, respectively. The space 150 between the first deformable plate 130 and the energizing plate 120 communicates with a space 154 (described later) between the energized plate 120 and the second deformable plate 140 through the vent hole 120b of the energized plate 120. Yes. A notch 78 b is formed in the lower surface 78 a on the inner peripheral side of the holder 80. A seal member 190 is disposed in the notch 78b. The seal member 190 is in contact with both the holder 80 and the energization plate 120, thereby sealing the space in the case 1, the space 150, and the space 154.

The second deformation plate 140 is disposed below the energization plate 120. That is, the second deformation plate 140 is disposed on the opposite side of the first deformation plate 130 with respect to the energization plate 120. The center part of the second deformation plate 140 protrudes downward. The outer peripheral portion of the second deformation plate 140 is connected to the outer peripheral portion 121 of the energization plate 120. A projecting portion 142 projecting upward is provided at the center of the upper surface of the second deformable plate 140. Above the protrusion 142, a contact portion 122 (a portion surrounded by the groove 120a) of the energization plate 120 is located. The pressure of the space 154 acts on the upper surface of the second deformation plate 140, and the pressure of the space in the case 1 acts on the lower surface of the second deformation plate 140. The protruding portion 142 corresponds to an example of a “projection”.

As shown in FIG. 7, the current interrupt device 110 has an energization path that connects the connection terminal 46, the energization plate 120, the first deformation plate 130, and the terminal 7 in series. For this reason, the electrode assembly 3 and the terminal 7 are electrically connected via the energization path of the current interrupt device 110.

Here, the interruption operation of the current interruption device 110 will be described. In the power storage device described above, the terminal 5 and the terminal 7 can be energized. When the internal pressure of the case 1 increases, the pressure acting on the lower surface of the second deformation plate 140 increases. On the other hand, the pressure of the space 154 sealed from the space in the case 1 acts on the upper surface of the second deformation plate 140. For this reason, when the pressure in the case 1 exceeds a predetermined value, the second deformable plate 140 changes from a downwardly convex state to a upwardly displaced state (see FIG. 8). At this time, the air in the space 154 moves to the space 150 through the vent hole 120b, and the pressure in the space 150 increases. When the second deformable plate 140 is displaced upward, the projecting portion 142 of the second deformable plate 140 collides with the contact portion 122 of the energizing plate 120, and the energizing plate 120 is broken at the groove 120a. Thereby, the 1st deformation board 130 reverses and the contact part 122 of the 1st deformation board 130 and the electricity supply board 120 displaces upwards (refer FIG. 8). For this reason, the electricity supply path which connects the electricity supply plate 120 and the 1st deformation plate 130 is interrupted | blocked, and the electrical connection between the electrode assembly 3 and the terminal 7 is interrupted | blocked. At this time, the first deformation plate 130 is insulated from the connection terminal 46, and the energization plate 120 is insulated from the terminal 7. The position of the protrusion 142 when the second deformation plate 140 is convex downward corresponds to an example of “first position”, and the protrusion 142 when the second deformation plate 140 is displaced upward. The position corresponds to an example of a “second position”. In addition, the state where the energization plate 120 is not broken and is in contact with the first deformable plate 130 at the contact portion 122 corresponds to an example of the “first state”. The state where the first deformation plate 130 and the first deformation plate 130 are electrically separated corresponds to an example of the “second state”. Also with this configuration, the same effects as the power storage device 100 of the first embodiment can be obtained.

As described above, the embodiments of the technology disclosed in the present specification have been described in detail. However, these are merely examples, and the current interrupting device and the manufacturing method disclosed in the present specification are variously modified from the above-described embodiments. Includes changes.

For example, in the above-described embodiment, the thickness t2 of the energizing plate 20 is smaller than the thickness t1 of the deforming plate in the entire area of the contact portion 22. However, the present invention is not limited to this configuration. If the relationship of t2 <t1 is established at the position where the weld bead 40 is formed (that is, the welded portion), t2> t1 may be satisfied at the position where the weld bead 40 is not formed in the contact portion 22. . That is, the thickness of the current-carrying plate 20 and the deformation plate 30 in the contact portion 22 may not be constant. In the above embodiment, the contact portion 22 of the energizing plate 20 is in surface contact with the deformable plate 30, but is not limited to this configuration. For example, an unevenness may be formed on the upper surface of the contact portion 22, and the convex portion of the contact portion 22 may be in contact with the lower surface of the deformation plate 30. Further, the welding is not limited to spot welding but may be continuous welding. Further, the thickness t2 of the contact portion 22 of the energization plate 20 and the thickness t1 of the deformation plate 30 may be equal.

In the above-described embodiment, the current-carrying plate 20 is divided into the contact portion 22 and the outer peripheral portion 21 by the groove portion 20a, but is not limited to this configuration. For example, the outline of the contact portion 22 may be located on the radially outer side of the groove portion 20a, and conversely, the outline of the contact portion 22 may be located on the radially inner side of the groove portion 20a. In the former case, the weld bead 40 is formed in a portion surrounded by the groove 20a.

In addition, the groove portion 20a may not be circular or may have a circular shape as long as the conduction between the energization plate 20 and the deformation plate 30 is interrupted when the internal pressure of the case 1 reaches a predetermined value. Also good. For example, a plurality of arc-shaped groove portions may be formed at intervals.

In the above-described embodiment, the thickness t4 of the energizing plate 20 in the groove 20a is smaller than the thickness t2 of the abutting portion 22 of the energizing plate 20. However, the present invention is not limited to this configuration. For example, you may comprise so that the thickness of the contact part 22 may become the smallest in the electricity supply board 20, instead of forming the groove part 20a. In this case, the mechanical strength of the energizing plate 20 is lowest at the contact portion 22.

Further, the current interrupt device 10 may be provided on the terminal 5 side, or may be provided on both the terminal 5 and the terminal 7. Moreover, in said Example, conduction | electrical_connection with the electricity supply board 20 is interrupted | blocked because the deformation | transformation board 30 inverts. However, the deformation method of the deformation plate 30 is not limited to inversion. For example, the configuration may be such that the central portion of the deformable plate 30 is bent upward so that the energizing plate 20 breaks starting from the groove portion 20a and the conduction between the deformable plate 30 and the energizing plate 20 is interrupted. The deformation plate 30 may be deformed in any way as long as the conduction between the deformation plate 30 and the energization plate 20 is interrupted. The same applies to the second deformation plate 140. In the step of welding the first deformation plate 130 to the base portion 15 of the terminal 7 in the second embodiment, the method is not limited to the method of irradiating the laser beam so as to make a round toward the first deformation plate 130, but spot welding. May be adopted.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

Claims

The electrode assembly housed in the case is electrically connected to the positive or negative terminal fixed to the mounting hole on the wall surface of the case, and the internal pressure of the case is a predetermined value. A current interrupting device that interrupts an energization path that electrically connects the electrode assembly and the terminal when rising beyond
An energization plate electrically connected to the electrode assembly;
A first deformation plate that is electrically connected to the terminal and is disposed on one side of the energization plate so as to face the energization plate;
The energization plate has a contact portion that is in contact with the first deformation plate in a state where the electrode assembly and the terminal are electrically connected,
The first deformation plate is electrically connected in a state where the electrode assembly and the terminal are in contact with the contact portion of the current supply plate in a state where the electrode assembly and the terminal are electrically connected to each other. In a non-conducting state with the terminal, it is electrically disconnected from the energizing plate in a state separated from the energizing plate,
The contact portion of the energization plate is in surface contact with the first deformation plate,
The contact surface of the contact portion with the first deformation plate is flat, and the contact surface of the first deformation plate with the contact portion is flat,
On the other side surface of the energization plate, a welding portion is provided in the contact portion,
The current interrupting device, wherein the current-carrying plate and the first deformation plate are joined at a position where the weld is provided, and the thickness of the current-carrying plate is equal to or less than the thickness of the first deformation plate.
The welded portion is disposed at a part of the contact portion of the energization plate,
2. The current interrupting device according to claim 1, wherein a thickness of the energization plate is equal to or less than a thickness of the first deformation plate in the entire area of the contact portion.
On the other side surface of the energization plate, a groove portion that makes a round of the outer periphery of the welded portion is provided, and the thickness of the energization plate in the portion where the groove portion is provided is provided with the groove portion. The current interrupting device according to claim 1, wherein the current interrupting device is smaller than a thickness of the energizing plate at a portion where there is no current.
When the current plate is viewed in plan, the groove is circular with a radius r,
When the thickness of the energizing plate in the portion where the groove is provided is t, and the area of the abutting portion of the energizing plate is A, the following relational expression:

The current interrupting device according to claim 3, wherein:
A second deformation plate that is disposed on the other side with respect to the energization plate, and further provided with a protrusion protruding toward the energization plate;
The second deformable plate is in a first state in which the protrusion is located at the first position and the energizing plate and the first deformable plate are in contact with each other when the electrode assembly and the terminal are electrically connected. When the electrode assembly and the terminal are non-conductive, the protrusion moves from the first position to the second position on the current plate side to separate the current plate and the first deformation plate. The current interrupting device according to any one of claims 1 to 4, wherein the current interrupting device can be switched between two states.
A power storage device comprising the current interrupt device according to any one of claims 1 to 5.
The power storage device according to claim 6, wherein the power storage device is a secondary battery.
A method for manufacturing a current interrupting device according to any one of claims 1 to 5,
A terminal fixing step of fixing the terminal to the mounting hole provided in the wall surface of the case;
A first deformation plate welding step of welding a surface on one side of the first deformation plate to a surface on the other side of the terminal;
An energizing plate arranging step of arranging the energizing plate so as to come into contact with at least part of the surface of the other side of the first deforming plate after the terminal fixing step and the first deforming plate welding step;
After the energizing plate placement step, energizing plate welding for welding the energizing plate and the first deformed plate by irradiating the energizing plate with a laser beam from the other side to the other side of the energizing plate. A process,
Before performing the current plate welding step, the thickness of the current plate at the position where the laser beam is to be irradiated is the thickness of the first deformation plate at the position where the current plate is joined by welding. The manufacturing method of the electric current interruption apparatus which is the following.