WO2019039081A1

WO2019039081A1 - Power storage device and method for manufacturing power storage device

Info

Publication number: WO2019039081A1
Application number: PCT/JP2018/024522
Authority: WO
Inventors: 栗田幹也; 小笠原雅人; 立花智明
Original assignee: 株式会社豊田自動織機
Priority date: 2017-08-22
Filing date: 2018-06-28
Publication date: 2019-02-28
Also published as: JP2019040668A

Abstract

This secondary battery is provided with: an electrode assembly; a case that houses the electrode assembly; a negative electrode terminal that is fixed to the case; and a current cutoff part that constitutes a part of a conduction path between the electrode assembly and the negative electrode terminal and that cuts off the conduction path when the inner pressure of the case reaches a set pressure. The current cutoff part is provided with a contact plate that is joined to the negative electrode terminal. The secondary battery is provided with a first conductive member that constitutes a part of the conduction path and that is joined to a negative electrode tab group of the electrode assembly by a first joint, a second conductive member that constitutes a part of the conduction path and that is joined to the contact plate by a second joint, and a fixed part of the first conductive member and the second conductive member.

Description

Power storage device and method of manufacturing power storage device

The present invention relates to a power storage device including a current interrupting unit and a method of manufacturing the power storage device.

Conventionally, a secondary battery such as a lithium ion secondary battery is mounted on a vehicle such as an EV (Electric Vehicle) or a PHV (Plug in Hybrid Vehicle) as a storage device for storing electric power used in electrical components. There is. The secondary battery has a case, an electrode assembly housed in the case, and a pair of electrode terminals of different polarities that protrude outside the case. As an electrode assembly, there is one in which a sheet-like positive electrode and a sheet-like negative electrode are laminated in a state in which a separator is interposed therebetween.

Some secondary batteries are provided with a current interrupting portion that interrupts current in response to an increase in internal pressure of the case. The current blocking portion is provided on a current path electrically connecting the electrode terminal and the electrode assembly. For example, the current interrupting portion disclosed in Patent Document 1 is electrically connected to the electrode terminal, and when the current interrupting portion is not in operation, a wedge-shaped reverse plate that protrudes toward the electrode assembly, and the electrode assembly And a plate-like conductive member joined. The reversing plate and the conductive member are connected by joining a part of the conductive member to the center of the reversing plate. Further, the surface of the conductive member close to the electrode assembly is provided with an annular groove which is exposed to the internal space of the case and which surrounds the joint portion with the reverse plate. In such a current blocking portion, when the internal pressure of the case reaches a predetermined set pressure, the conductive member is broken at the groove, and the reversing plate is convexly reversed to the electrode terminal side together with the bonding portion of the conductive member. As a result, the conduction between the conductive member and the reverse plate is cut off, and the conduction path between the electrode assembly and the electrode terminal is cut off.

JP, 2010-212034, A

By the way, in the case of bonding the contact plate and the conductive member after bonding the electrode assembly and the conductive member in the manufacture of a secondary battery provided with a current interrupting portion, this occurs when the contact plate and the conductive member are bonded. The displacement of the conductive member generates a stress in the first joint portion where the electrode assembly and the conductive member are joined. Conversely, when the electrode assembly and the conductive member are bonded after the contact plate and the conductive member are bonded, the contact plate and the conductive member are displaced due to the displacement of the conductive member generated when the electrode assembly and the conductive member are bonded. And a stress is generated in a second joint portion joined with the second joint portion. Such stress may, for example, reduce the bonding strength of the bonding portion.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to provide a power storage device and a method of manufacturing the power storage device capable of reducing the stress generated in the first joint portion and the second joint portion. is there.

The storage device for solving the above problems is an electrode having a tab group in which electrodes of different polarities are stacked in a state of being mutually insulated and tabs having a shape protruding from one side of the electrodes are stacked with the same polarity. An assembly, a case accommodating the electrode assembly, a pair of electrode terminals fixed to the case, and a part of a conduction path between one of the electrode terminals and the electrode assembly; And a current interrupting unit for interrupting the current path when the internal pressure reaches a set pressure, wherein the current interrupting unit is a power storage device having a contact plate joined to the one of the electrode terminals, which is a first junction A second conductive member joined to the tab group by the second part and joined to the contact plate by the second joint and a first conductive member constituting a part of the conductive path, and a second conductive part constituting a part of the conductive path Member, and the first conductive portion A fixing portion of the second conductive member and the gist in that it comprises.

According to this, after the tab group and the first conductive member are joined and the contact plate and the second conductive member are joined, the first conductive member and the second conductive member can be fixed by the fixing portion. In the case where the tab group is joined to one end of one conductive member and the contact plate is joined to the other end, the distance between the first joint and the fixed part and the distance between the second joint and the fixed part respectively The distance between the junction of the group and the conductive member and the junction of the contact plate and the conductive member is shorter. Therefore, compared with the case where the tab group and the contact plate are joined to one conductive member, the stress generated in the first joint portion and the second joint portion can be reduced.

Further, in the power storage device, preferably, the fixing portion is formed by resistance welding between the first conductive member and the second conductive member.
For example, when the fixed portion is formed by ultrasonic welding, ultrasonic vibration may be transmitted to the second bonding portion, and the second bonding portion may be damaged, whereby the function of the current blocking portion may be impaired. Since the fixing portion is formed, the vibration accompanying the welding is suppressed, and the damage of the second joint can be suppressed. Further, when the fixed portion is formed by bolting, the number of parts of the power storage device increases, but since the fixed portion is formed by resistance welding, the number of parts of the power storage device does not increase.

In the power storage device, preferably, the first bonding portion is formed by ultrasonic welding.
When the first joint is formed by laser welding, the thermal influence on the electrodes and separators constituting the electrode assembly is large, and there is a possibility that spatter etc. may occur to adhere to the electrode assembly. (1) Since the bonding portion is formed, the thermal influence on the electrode and the separator can be reduced, and the occurrence of sputtering or the like can be suppressed.

A method of manufacturing a storage device for solving the above problems is a tab group in which electrodes of different polarities are stacked in a state of being mutually insulated and tabs having a shape protruding from one side of the electrodes are stacked with the same polarity. An electrode assembly having the electrode assembly, a case accommodating the electrode assembly, a pair of electrode terminals fixed to the case, and a part of the current path of one of the electrode terminals and the electrode assembly; A method of manufacturing a power storage device, comprising: a current interrupting portion interrupting the current path when the internal pressure of the case reaches a set pressure, wherein the current interrupting portion has a contact plate joined to the one electrode terminal. And bonding the tab group and the first conductive member to form a first joint, and bonding the contact plate and the second conductive member to form a second joint; After the step, the first conductive member and the first conductive member A fixing step of fixing the conductive members, to include the subject matter.

According to this method, the fixing step is performed after the bonding step. In the case where the tab group is joined to one end of one conductive member and the contact plate is joined to the other end, the distance between the first joint and the fixed part and the distance between the second joint and the fixed part respectively The distance between the junction of the group and the conductive member and the junction of the contact plate and the conductive member is shorter. Therefore, compared with the case where a tab group and a contact plate are joined to one conductive member, the stress generated in the first joint and the second joint can be reduced.

In the method of manufacturing the power storage device, preferably, the fixing step is performed by resistance welding.
For example, in the case of fixing by ultrasonic welding, ultrasonic vibration may propagate to the second joint and damage to the second joint may impair the function of the current interrupting part, but fixing by resistance welding Thus, it is possible to suppress the vibration accompanying the welding and fix the second joint without damaging it. Further, when fixing by bolting, the number of parts of the power storage device increases, but by fixing by resistance welding, the number of parts of the power storage device does not increase.

Further, in the method of manufacturing the power storage device, in the bonding step, the first bonding portion is preferably formed by ultrasonic welding.
When the first joint is formed by laser welding, the thermal influence on the electrodes and separators constituting the electrode assembly is large, and there is a possibility that spattering may occur to adhere to the electrode assembly. By doing so, the thermal influence on the electrodes and the separator can be reduced, and the occurrence of sputtering and the like can be suppressed.

Further, in the method of manufacturing the power storage device, in the bonding step, the second bonding portion is preferably formed by laser welding.
According to this, since the second bonding portion is formed by laser welding, bonding can be performed even in a small area where the contact plate and the second conductive member are in contact with each other.

According to the present invention, the stress generated in the first joint and the second joint can be reduced.

Sectional drawing which shows the secondary battery of embodiment. The partially expanded sectional view which shows a current interruption part. The fragmentary sectional view which shows a 1st joining process. (A)-(c) is a fragmentary sectional view which shows a 2nd joining process. The fragmentary sectional view which shows a fixation process.

Hereinafter, an electric storage device and a method of manufacturing the electric storage device will be described with reference to FIGS. 1 to 5 according to an embodiment in which a secondary battery and a method of manufacturing a secondary battery are embodied.
As shown in FIG. 1, the secondary battery 10 as a power storage device is a rectangular lithium ion secondary battery. The secondary battery 10 includes a flat rectangular box-like case 11. The case 11 has a square box-like case main body 12 having an opening 12 a and a rectangular flat lid 13 covering the opening 12 a of the case main body 12. The case body 12 and the lid 13 are made of metal (for example, aluminum). The case body 12 and the lid 13 are welded. The lid 13 has two through holes 13 b penetrating in the thickness direction.

The secondary battery 10 includes a rectangular parallelepiped electrode assembly 14 housed in a case 11 and an electrolyte (not shown). The electrode assembly 14 has a layered structure in which a sheet-like positive electrode and a sheet-like negative electrode are alternately stacked in a state in which a resin separator is interposed.

The positive electrode has a rectangular positive electrode metal foil (for example, aluminum foil) and a positive electrode active material layer present on both sides of the positive electrode metal foil. The positive electrode has a positive electrode tab 17 as a tab protruding from one side of the positive electrode. The negative electrode has a rectangular negative electrode metal foil (for example, copper foil) and a negative electrode active material layer present on both sides of the negative electrode metal foil. The negative electrode has a negative electrode tab 18 as a tab protruding from one side of the negative electrode.

The electrode assembly 14 has a positive electrode tab group 17a as a tab group in which the positive electrode tabs 17 of the respective positive electrodes are stacked, and a negative electrode tab group 18a as a tab group in which the negative electrodes 18 of each negative electrode are stacked. The positive electrode tab group 17 a and the negative electrode tab group 18 a are present on the end face 14 a facing the lid 13 in the electrode assembly 14.

The secondary battery 10 has a negative electrode terminal 16 as an electrode terminal and a positive electrode terminal 15 as an electrode terminal having a polarity different from that of the negative electrode terminal 16. The positive electrode terminal 15 and the negative electrode terminal 16 are fixed to the lid 13 of the case 11 in a state of penetrating the through holes 13 b of the lid 13. A part of the positive electrode terminal 15 and the negative electrode terminal 16 protrudes inside the case 11, and a part thereof protrudes outside the case 11.

The secondary battery 10 includes an insulating first seal member 20. The first seal member 20 includes a cylindrical portion 20 a fitted in the through hole 13 b through which the negative electrode terminal 16 penetrates, and a main portion 20 b disposed along the inner surface of the lid 13. The secondary battery 10 also includes an insulating second seal member 21. The second seal member 21 includes a cylindrical portion 21 a fitted in the through hole 13 b through which the positive electrode terminal 15 passes, and also includes a main portion 21 b disposed along the inner surface of the lid 13.

The negative electrode terminal 16 includes an outer nut 22, an inner nut 23 and a bolt 24. The external nut 22 is used to connect the negative electrode terminal 16 and the bus bar (not shown). The internal nut 23 is attached to the first seal member 20. A portion of the inner nut 23 passes through the through hole 13 b. The bolt 24 is fastened to the internal nut 23. A third seal member 25 intervenes between the bolt 24 and the lid 13. The negative electrode terminal 16 is insulated from the lid 13 by the first seal member 20 and the third seal member 25.

As shown in FIGS. 1 and 2, the internal nut 23 is electrically connected to the negative electrode tab group 18 a via the current blocking portion 80, the first conductive member 41, and the second conductive member 42. The first conductive member 41 has an elongated plate shape. The longitudinal direction of the first conductive member 41 extends in the longitudinal direction of the lid 13. A part of the first conductive member 41 is joined to the negative electrode tab group 18 a. A portion where the first conductive member 41 and the negative electrode tab group 18 a are joined is referred to as a first joint portion 43. The second conductive member 42 has an elongated plate shape. The longitudinal direction of the second conductive member 42 extends in the longitudinal direction of the lid 13. A part of the second conductive member 42 is joined to the current interrupting unit 80. A joint portion between the second conductive member 42 and the current blocking portion 80 is referred to as a second joint portion 44. The second conductive member 42 has four through holes 42 d (two are shown in FIG. 2) penetrating in the thickness direction the portion on the negative electrode terminal 16 side in the longitudinal direction. A portion of the first conductive member 41 extending from the first bonding portion 43 toward the second conductive member 42 and a portion of the second conductive member 42 extending from the second bonding portion 44 toward the first conductive member 41 are mutually different It is overlapping. The portions where the first conductive member 41 and the second conductive member 42 overlap with each other are fixed and electrically connected. A portion where the first conductive member 41 and the second conductive member 42 are fixed is referred to as a fixed portion 45. The first conductive member 41 and the second conductive member 42 connected by the fixing portion 45 constitute a part of the current passage of the electrode assembly 14 and the negative electrode terminal 16. The current interrupting unit 80 will be described later.

The positive electrode terminal 15 includes an outer nut 32, an inner nut 33, and a bolt 34. The external nut 32 is used for connection between the positive electrode terminal 15 and a bus bar (not shown). The internal nut 33 is attached to the second seal member 21. A part of the internal nut 33 passes through the through hole 13 b. The bolt 34 is fastened to the internal nut 33. A fourth seal member 35 intervenes between the bolt 34 and the lid 13. The positive electrode terminal 15 is insulated from the lid 13 by the second seal member 21 and the fourth seal member 35. The internal nut 33 of the positive electrode terminal 15 is electrically connected to the positive electrode tab group 17 a of the electrode assembly 14 via the plate-like positive electrode conductive member 50. One end of the positive electrode conductive member 50 in the longitudinal direction is joined to the internal nut 33, and the other end in the longitudinal direction is joined to the positive electrode tab group 17a. Therefore, the positive electrode conductive member 50 constitutes a current path for the electrode assembly 14 and the positive electrode terminal 15.

Next, the current interrupting unit 80 will be described.
The current interrupting unit 80 is disposed inside the case 11 and interrupts the current flowing through the electrode assembly 14 and the negative electrode terminal 16 when the internal pressure of the case 11 reaches a predetermined set pressure. The internal pressure of the case 11 may increase due to the gas generated by the electrode assembly 14 or the electrolyte, such as during overcharge or overdischarge of the secondary battery 10. The set pressure is set to a pressure slightly lower than a pressure at which a crack or break occurs in the case 11 itself or the joint portion between the case body 12 and the lid 13 due to the increase of the internal pressure of the case 11. The current interrupting portion 80 is located on the conduction path between the internal nut 23 of the negative electrode terminal 16 and the second conductive member 42. As described above, the negative electrode tab group 18 a is electrically connected to the second conductive member 42 through the first conductive member 41, and the second conductive member 42 is connected to the negative electrode terminal 16 through the current blocking portion 80. Electrically connected to the internal nut 23 of the Thus, a conduction path between the electrode assembly 14 and the negative electrode terminal 16 is configured.

When operated by the gas generated inside the case 11, the current blocking unit 80 cuts off the electrical connection between the internal nut 23 of the negative electrode terminal 16 and the second conductive member 42. That is, the current interrupting unit 80 constitutes a part of the current passage when it is not in operation, and blocks the current passage when it is activated by receiving the pressure of the gas generated inside the case 11.

As shown in FIG. 2, the current interrupting unit 80 includes a contact plate 81. The contact plate 81 is joined to the second conductive member 42 and the internal nut 23 of the negative electrode terminal 16, and constitutes a part of the conduction path between the electrode assembly 14 and the negative electrode terminal 16. The contact plate 81 is made of a conductive material. When the current interrupting unit 80 is not in operation, the contact plate 81 is in the shape of a hook that is convex toward the electrode assembly 14. The contact plate 81 covers the female screw hole 23 a of the internal nut 23 from the electrode assembly 14 side. The peripheral edge portion of the contact plate 81 and the internal nut 23 are joined. The portion of the contact plate 81 convex toward the electrode assembly 14 and the second conductive member 42 are welded and joined. The above-mentioned second joint portion 44 is a portion where the contact plate 81 and the second conductive member 42 are welded and joined.

In the second conductive member 42, the surface closer to the lid 13 and the surface to which the contact plate 81 is joined is taken as a first surface 42a, which is a surface parallel to the first surface 42a and closer to the electrode assembly 14 The second surface 42b is used. The second conductive member 42 includes a recess 42 c recessed in a mortar shape from the second surface 42 b toward the lid 13. The second joint portion 44 is located at the bottom of the recess 42c. The second conductive member 42 has a breaking groove 84 at the bottom of the recess 42 c. The fracture groove 84 is an annular shape surrounding the second joint 44.

The internal nut 23 of the negative electrode terminal 16 and the second conductive member 42 are electrically connected via the contact plate 81. Since the contact plate 81 has a bowl shape, a gap between the inner nut 23 and the second conductive member 42 exists around the contact plate 81 as much as the contact plate 81 is convex from the inner nut 23. The current interrupting unit 80 has an insulating ring 82 disposed in the gap between the internal nut 23 and the second conductive member 42. The insulating ring 82 is disposed below the periphery of the contact plate 81, and holds the internal nut 23 and the second conductive member 42 at a predetermined distance. In addition, a seal ring 83 is disposed on the outer peripheral side of the insulating ring 82.

The current interrupting unit 80 has a deformation plate 85 that receives and deforms the internal pressure of the case 11. The deformation plate 85 is a diaphragm made of an elastic material, for example, a metal plate, and is disposed at a position closer to the electrode assembly 14 than the second conductive member 42. The deformation plate 85 has a disk shape and covers the recess 42 c from the electrode assembly 14 side. The peripheral portion of the deformation plate 85 and the second conductive member 42 are joined along the entire periphery of the peripheral portion of the deformation plate 85. The current interrupting unit 80 airtightly separates the inside of the case 11 from the outside of the case 11.

The deformation plate 85 is convex from the lid 13 side to the electrode assembly 14 side (downward) when the current blocking portion 80 is not operated. The deformation plate 85 has a protrusion 85 a protruding toward the lid 13 at a position facing the second joint portion 44 in the convex portion. The protrusion 85 a is covered by a cap 86. The cap 86 is made of an insulating material and is opposed to the second joint portion 44 surrounded by the breaking groove 84. In the deformation plate 85, one surface closer to the electrode assembly 14 receives the pressure in the internal space of the case 11, and the other surface closer to the lid 13 is the pressure in the space isolated from the internal space of the case 11 (atmospheric pressure )Is receiving. The space isolated from the internal space of the case 11 is a space surrounded by the second surface 42 b of the second conductive member 42 and the deformation plate 85.

The current interrupting unit 80 includes a cylindrical support member 54. The support member 54 is made of a thermoplastic resin (for example, PPS or the like). Inside the support member 54, the internal nut 23, the contact plate 81, the insulating ring 82, and the seal ring 83 are accommodated. The surface of the support member 54 facing the lid 13 is in contact with the inner surface of the lid 13. The support member 54 is provided with a protruding piece 54 e at the inner peripheral edge close to the lid 13 so as to protrude toward the inner nut 23. The projecting piece 54 e is in contact with the internal nut 23. The support member 54 includes a caulking boss 54 a, and the caulking boss 54 a protrudes toward the electrode assembly 14. The caulking bosses 54 a are present at the four corners of the surface of the support member 54 facing the electrode assembly 14. The crimping boss 54a passes through the through hole 42d of the second conductive member 42, and the second conductive member 42 is fixed to the support member 54 by heat caulking of the crimping boss 54a. The internal nut 23, the contact plate 81, the insulating ring 82, and the seal ring 83 are sandwiched and supported by the projecting piece 54e and the second conductive member 42 fixed to the support member 54.

In the secondary battery 10 including the current interrupting unit 80 configured as described above, when gas is generated in the electrode assembly 14 during overcharge and overdischarge, the internal pressure of the case 11 increases. When the internal pressure reaches the set pressure, the deformation plate 85 that receives the pressure deforms so as to be convex toward the second bonding portion 44. Then, the projection 85a covered by the cap 86 collides with the second joint portion 44 surrounded by the breaking groove 84, and the second joint portion 44 in the second conductive member 42 is broken, and the contact plate 81 is covered Transform towards 13 As a result, the contact plate 81 and the second conductive member 42 are separated, so that the electrical connection between the second conductive member 42 and the negative electrode terminal 16 is physically cut off, and the electrode assembly 14 and the negative electrode terminal 16 are separated. The current flowing between them is cut off.

Next, a method of manufacturing the secondary battery 10 will be described.
The method of manufacturing the secondary battery 10 includes the steps of manufacturing the electrode assembly 14, forming the current path on the positive electrode side, forming the current path on the negative electrode side, and covering the positive electrode terminal 15 and the negative electrode terminal 16. And a step of fixing the lid 13 to the case main body 12.

First, in the process of manufacturing the electrode assembly 14, the sheet-like positive electrode and the sheet-like negative electrode are alternately stacked in a state in which the separator is interposed therebetween to manufacture the electrode assembly 14 and a positive electrode. A positive electrode tab group 17a in which the tabs 17 are stacked and a negative electrode tab group 18a in which the negative electrode tabs 18 are stacked are manufactured. In the step of forming the current-carrying path on the positive electrode side, the positive electrode tab group 17a and the positive electrode conductive member 50 are joined by ultrasonic welding.

The step of forming the current path on the negative electrode side includes a step of bonding the negative electrode tab group 18a and the first conductive member 41 as a first bonding step, and a current blocking portion 80 and a second conductive member 42 as a second bonding step. And a fixing step of fixing the first conductive member 41 and the second conductive member 42.

As shown in FIG. 3, in the first bonding step, the negative electrode tab group 18 a and the first conductive member 41 are bonded by ultrasonic welding to form a first bonding portion 43. The first conductive member 41 is superimposed on the negative electrode tab group 18a, and the negative electrode tab group 18a and the first conductive member 41 are sandwiched by a pair of horns 71 for ultrasonic welding. Then, ultrasonic vibration is applied to the negative electrode tab group 18a and the first conductive member 41 by the pair of horns 71, and the negative electrode tab group 18a and the first conductive member 41 are welded.

As shown in FIG. 4A, in the second bonding step, first, laser is irradiated from the side of the deformation plate 85 by the laser welder 72, and the outer peripheral portion of the deformation plate 85 and the second surface of the second conductive member 42 Join with 42b. Next, the peripheral edge portion of the contact plate 81 is laser welded to the inner nut 23 and joined. After the joined internal nut 23 and contact plate 81 are accommodated inside the support member 54, the insulating ring 82 and the seal ring 83 are accommodated inside the support member 54. Next, the caulking boss 54 a of the support member 54 is penetrated through the through hole 42 d of the second conductive member 42. Next, heat is applied to the caulking boss 54 a protruding from the through hole 42 d of the second conductive member 42 by a heater chip (not shown). Then, as shown in FIG. 4B, the caulking boss 54a is thermally deformed, and the second conductive member 42 is fixed to the support member 54. That is, the support member 54 and the second conductive member 42 are integrated by thermal caulking. Next, as shown in FIG. 4C, a laser welder 72 inserted into the female screw hole 23a of the internal nut 23 irradiates a laser from the first surface 42a side of the second conductive member 42, and the second conductivity The member 42 and the contact plate 81 are joined by laser welding. Thereby, the second bonding portion 44 is formed.

As shown in FIG. 5, in the fixing step, the first conductive member 41 and the second conductive member 42 are fixed by resistance welding to form a fixing portion 45. The first conductive member 41 is superimposed on the second conductive member 42 so that the first conductive member 41 is on the upper side than the second conductive member 42, and the pair of welding electrodes 73 forms the first conductive member 41 and the second conductive member 42. Sandwich the Then, a voltage is applied to the welding electrode 73, and the first conductive member 41 and the second conductive member 42 are resistance-welded. Thereby, the welding part of the 1st electric conduction member 41 and the 2nd electric conduction member 42 is formed as fixed part 45, and current interception part 80 is completed.

In the process of fixing the positive electrode terminal 15 and the negative electrode terminal 16 to the lid 13, the

bolts

24 and 34 penetrating the through holes 13 b are fastened to the respective

internal nuts

23 and 33, and the positive electrode terminal 15 and the negative electrode terminal 16 are covered 13 Fix to At this time, the positive electrode terminal 15 and the negative electrode terminal 16 are insulated from the lid 13 by the first to

fourth seal members

20, 21, 25, 35. Finally, the lid 13 is fixed to the case body 12 to form the case 11, and the secondary battery 10 is completed.

Next, the effects of the present embodiment will be described along with the actions.
(1) The fixing step of forming the fixing portion 45 of the first conductive member 41 and the second conductive member 42 includes bonding the negative electrode tab group 18 a and the first conductive member 41 to form the first bonding portion 43. The bonding step and the second bonding step of bonding the current blocking portion 80 and the second conductive member 42 and forming the second bonding portion 44 are performed. The distance between the first bonding portion 43 and the fixing portion 45 and the distance between the second bonding portion 44 and the fixing portion 45 are such that the negative electrode tab group is bonded to one end of one conductive member and the contact plate is bonded to the other end It becomes shorter than the distance between joints in the case of As the distance between the first bonding portion 43 and the fixing portion 45 and the distance between the second bonding portion 44 and the fixing portion 45 become shorter, the first bonding portion 43 and the second bonding portion 44 can be formed when the fixing portion 45 is formed. The stress generated is reduced. Therefore, the stress generated in the first bonding portion 43 and the second bonding portion 44 can be reduced.

(2) The fixing portion 45 is formed by resistance welding the first conductive member 41 and the second conductive member 42 in the fixing step. For example, in the case of forming the fixed portion 45 by ultrasonic welding, ultrasonic vibration may propagate to the second bonding portion 44 and damage to the second bonding portion 44 may impair the function of the current blocking portion 80. By forming the fixing portion 45 by resistance welding, it is possible to suppress the vibration accompanying the welding and fix the second joint portion 44 without damaging it. Moreover, when forming the fixing portion 45 by bolting, the number of parts of the secondary battery 10 increases, but forming the fixing portion 45 by resistance welding does not increase the number of parts of the secondary battery 10.

(3) The first bonding portion 43 is formed by bonding the negative electrode tab group 18a and the first conductive member 41 by ultrasonic welding in the first bonding step. For example, in the case of forming the first joint portion 43 by laser welding, the electrodes and separators constituting the electrode assembly 14 have a large thermal effect, and there is a risk that spattering may occur and adhere to the electrode assembly 14. By forming the first bonding portion 43 by ultrasonic welding, it is possible to reduce the thermal effect on the electrode and the separator, and to suppress the occurrence of spatter and the like.

(4) The second bonding portion 44 is formed by bonding the contact plate 81 and the second conductive member 42 by laser welding in the second bonding step. In the case of laser welding, welding in a small area is possible. Therefore, the second bonding portion 44 can be formed even in a small area where the contact plate 81 and the second conductive member 42 are in contact with each other.

The above embodiment may be modified as follows.
The order of the step of bonding the negative electrode tab group 18a and the first conductive member 41 and the step of bonding the current blocking portion 80 and the second conductive member 42 does not matter. That is, the step of bonding the current blocking portion 80 and the second conductive member 42 may be a first bonding step, and the step of bonding the negative electrode tab group 18a and the first conductive member 41 may be a second bonding step. Further, the step of bonding the negative electrode tab group 18a and the first conductive member 41 and the step of bonding the current blocking portion 80 and the second conductive member 42 may be performed simultaneously.

The method of joining the first conductive member 41 and the negative electrode tab group 18a is not limited to ultrasonic welding, and may be another joining method (for example, laser welding).
The method of joining the second conductive member 42 and the deformation plate 85 is not limited to laser welding, and may be another method (for example, resistance welding) other than ultrasonic welding.

The method of joining the contact plate 81 and the internal nut 23 is not limited to laser welding, and may be another method (for example, resistance welding) other than ultrasonic welding.
The method of joining the second conductive member 42 and the contact plate 81 is not limited to laser welding, and may be another method (for example, resistance welding) other than ultrasonic welding.

The fixing method of the first conductive member 41 and the second conductive member 42 is not limited to bonding by resistance welding, and may be another method other than ultrasonic welding. For example, the first conductive member 41 and the second conductive member 42 are fixed by forming a through hole in the first conductive member 41 and the second conductive member 42 and fastening a bolt penetrating the through hole to a nut. May be

In the above embodiment, when the first conductive member 41 and the second conductive member 42 are fixed, the first conductive member 41 is overlapped so as to be above the second conductive member 42, but the first conductive member 41 is the first conductive member. The members 41 may be stacked so as to be lower than the second conductive member 42.

The current interrupting unit 80 may be provided on the positive electrode terminal 15.
The positive electrode terminal 15 and the negative electrode terminal 16 may not be integrated with the external nut, the internal nut, and the bolt, but may be configured as a single bolt.

The specific configuration of the current interrupting unit 80 may be changed. For example, the breaking groove 84 may not be annular, and may be a recess provided at an outer side of the second joint portion 44 with a space. Also, the deformation plate 85 may be omitted. In this case, the second surface 42 b of the second conductive member 42 is a surface that receives the internal pressure of the case 11.

The specific configuration of the electrode assembly 14 may be changed. For example, the shapes of the positive electrode, the negative electrode, and the separator may be changed. For example, it may be square in a front view, and the separator may be in the form of a bag that wraps the positive electrode. Furthermore, the electrode assembly 14 may be a wound electrode assembly in which a strip-like positive electrode and a strip-like negative electrode are wound with a separator interposed therebetween.

The embodiment can also be applied to power storage devices other than secondary batteries, such as capacitors.
The secondary battery 10 may be a stationary battery for use in a house or the like as well as for a vehicle.

DESCRIPTION OF SYMBOLS 10 Secondary battery 11 Case 14 Electrode assembly 15 Negative electrode terminal as a terminal 16 Negative electrode terminal as a terminal 17 Positive electrode tab as tab 17a Positive electrode tab group as tab group 18 Negative electrode tab as tab 18a Negative electrode tab group as tab group 41 first conductive member 42 second conductive member 43 first joint portion 44 second joint portion 45 fixing portion 80 current interrupting portion 81 contact plate

Claims

An electrode assembly having a tab group in which electrodes of different polarities are stacked in a mutually insulated state, and tabs having a shape protruding from one side of the electrodes are stacked with the same polarity;
A case containing the electrode assembly;
A pair of electrode terminals fixed to the case;
A current interrupting unit which constitutes a part of the current flow path between one of the electrode terminals and the electrode assembly, and cuts off the current flow path when the internal pressure of the case reaches a set pressure;
Have
The current blocking unit is a power storage device having a contact plate joined to the one electrode terminal,
A first conductive member joined to the tab group by a first joining portion and forming a part of the current path;
A second conductive member which is joined to the contact plate by a second joint and which constitutes a part of the current path;
A fixing portion of the first conductive member and the second conductive member;
A power storage device comprising:
The power storage device according to claim 1, wherein the fixing portion is formed by resistance welding of the first conductive member and the second conductive member.
The power storage device according to claim 1, wherein the first joint portion is formed by ultrasonic welding.
An electrode assembly having a tab group in which electrodes of different polarities are stacked in a mutually insulated state, and tabs having a shape protruding from one side of the electrodes are stacked with the same polarity;
A case containing the electrode assembly;
A pair of electrode terminals fixed to the case;
A current interrupting unit which constitutes a part of the current flow path between one of the electrode terminals and the electrode assembly, and cuts off the current flow path when the internal pressure of the case reaches a set pressure;
Have
The current blocking portion may be a method of manufacturing a power storage device having a contact plate joined to the one electrode terminal,
Bonding the tabs and the first conductive member to form a first joint, and bonding the contact plate and the second conductive member to form a second joint;
A fixing step of fixing the first conductive member and the second conductive member after the bonding step;
A method of manufacturing a power storage device, comprising:
The method of manufacturing a power storage device according to claim 4, wherein the fixing step is performed by resistance welding.
The method for manufacturing a power storage device according to claim 4, wherein the first bonding portion is formed by ultrasonic welding in the bonding step.
The method for manufacturing a power storage device according to any one of claims 4 to 6, wherein the second bonding portion is formed by laser welding in the bonding step.