JP6597016B2 - Power storage device - Google Patents

Description

  The present invention relates to a power storage device including a current interrupting unit.

  Conventionally, secondary batteries such as lithium ion secondary batteries have been installed in vehicles such as EVs (Electric Vehicles) and PHVs (Plug in Hybrid Vehicles) as power storage devices for storing electric power used in electrical components. Yes. The secondary battery includes a case, an electrode assembly housed in the case, and two electrode terminals that protrude outside the case and have different polarities. Some secondary batteries have an electrode terminal with a current interrupting part that interrupts the current in response to an increase in the internal pressure of the case. The current interrupting part is provided on an energization path that electrically connects the electrode terminal and the electrode assembly.

  As shown in FIG. 5, the current interrupting unit 90 disclosed in Patent Document 1 includes a contact plate 92 connected to a negative external terminal (electrode terminal) 89 and an energization plate (conductive member) connected to the contact plate 92. 91 and a deforming plate 93 disposed opposite to the inside of the case with respect to the energizing plate 91.

  The energizing plate 91 has a breaking portion 91a that breaks when a predetermined load is applied. The contact plate 92 is disposed so as to face the energizing plate 91 and is electrically connected to the energizing plate 91 at a portion surrounded by the fracture portion 91a. The energization plate 91 and the contact plate 92 constitute a part of the energization path. The deformable plate 93 has a first surface facing the first space 94 a held at the same pressure as the internal pressure of the case 95, and a second space 94 b whose other surface is isolated from the internal space of the case 95. It faces the current-carrying plate 91.

  The energization plate 91, the contact plate 92, and the deformation plate 93 are fixed inside the cylindrical support member 96. Further, a sealing member 97 is disposed between the contact plate 92 and the energizing plate 91 at the periphery, and the contact plate 92 and the energizing plate 91 are insulated at the periphery. When the internal pressure of the case 95 rises above a predetermined level, the deformed plate 93 is deformed to the energizing plate 91 side as shown by a two-dot chain line in FIG. The plate 91 is broken. As a result, the energization of the energizing plate 91 and the contact plate 92 is interrupted, and the current flowing between the electrode assembly and the electrode terminal is interrupted.

JP 2014-232690 A

  However, in the current interrupting unit 90 of Patent Document 1, when the energizing plate 91 is broken and the energizing plate 91 and the contact plate 92 are divided, a large voltage is applied between the energizing plate 91 and the contact plate 92. Sometimes. At this time, if an electrolyte exists between the current-carrying plate 91 and the contact plate 92 on the outer peripheral side of the seal member 97, a conductive foreign matter is generated from the electrolyte and enters into a liquid junction. May re-energize.

  The present invention has been made paying attention to such problems existing in the prior art, and its purpose is to suppress the liquid junction between the conductive member and the electrode terminal during the operation of the current interrupting portion. An object of the present invention is to provide a power storage device that can be used.

A power storage device for solving the above problem connects a pair of electrode terminals fixed to a wall portion facing an end face of an electrode assembly in a case, and the electrode assembly and the electrode terminals in the case. A power storage device comprising: a conductive member; and a current interrupting unit that interrupts an energization path between one electrode terminal and the electrode assembly when the internal pressure of the case exceeds a set pressure, wherein the one electrode terminal is A terminal head portion electrically connected to the conductive member in the case; a terminal shaft portion standing from a seating surface of the terminal head portion and projecting out of the case through the wall portion; A connecting hole penetrating in the axial direction connecting the terminal shaft portion and the terminal head portion, and the current interrupting portion is directed toward the conductive member in a state of covering an opening at the terminal head portion in the connecting hole. Convex-shaped, and the outer periphery is the terminal head Together they are joined to includes a contact plate portion which is convex is joined to the joint surface of the conductive member toward the conductive member, and a cylindrical cover surrounding the outer peripheral surface of said terminal head, wherein An outer peripheral surface of the terminal head is a tapered surface, an insulating ring is disposed between the terminal head and the conductive member, an outer peripheral surface of the terminal head, an inner peripheral surface of the cover, and the conductive member And a liquid gasket filled in a filling space surrounded by the joint surface and the outer peripheral surface of the insulating ring .

  According to this, the liquid gasket filled in the filling space is in close contact with each surface defining the filling space. In the filling space, the outer peripheral surface of the terminal head and the joint surface of the conductive member are exposed, but both surfaces are insulated between both surfaces in a state in which the liquid gasket is tightly filled. That is, the liquid gasket is tightly filled between both surfaces, and there is no gap, so that the electrolyte solution is prevented from entering between the both surfaces. For this reason, even if a large voltage is applied between the conductive member and the electrode terminal when the current interrupting part is activated and the conductive member is broken and the conduction between the conductive member and the terminal head is interrupted, the conductive member A liquid junction between the member and the electrode terminal is avoided, and re-energization between the conductive member and the electrode terminal is avoided.

In the power storage device, the liquid gasket is silicone.
According to this, the liquid gasket can be made resistant to the electrolytic solution, and the liquid gasket is prevented from being deteriorated by the electrolytic solution.

Further, the power storage device, the insulating ring, while being placed between the conductive member and the terminal head while surrounding the periphery of the contact plate, the outer peripheral surface of said insulating ring in the filling space The outer peripheral surface of the terminal head that faces and faces the filling space may be a tapered surface that widens along the axial direction toward the terminal shaft portion.

According to this, the terminal head and the conductive member can be easily separated from each other by a predetermined distance by the insulating ring.
The power storage device is a secondary battery.

  According to the present invention, it is possible to suppress a liquid junction between the conductive member and the electrode terminal during the operation of the current interrupting unit.

The perspective view which shows typically the secondary battery disassembled partially. The perspective view which shows typically the secondary battery fractured | ruptured partially. FIG. 3 is a sectional view taken along line 3-3 shown in FIG. 2. Sectional drawing which shows the filling operation | work of a liquid gasket. The figure explaining background art.

Hereinafter, an embodiment in which the power storage device is embodied as a secondary battery will be described with reference to FIGS.
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 square box-shaped case 11. The case 11 includes a rectangular box-shaped case main body 12 having an opening 12 a and a flat lid 13 that closes 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 13b penetrating in the thickness direction.

  The secondary battery 10 includes an electrolyte solution (not shown) accommodated in the case 11. The secondary battery 10 includes 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 terminal 15 and the negative terminal 16 are fixed to a lid 13 as a wall portion of the case 11. Further, a part of the positive electrode terminal 15 and the negative electrode terminal 16 protrudes inside the case 11, and a part protrudes outside the case 11. The positive terminal 15 and the negative terminal 16 will be described in detail later.

  The secondary battery 10 includes a rectangular parallelepiped electrode assembly 14 accommodated in a case 11. The electrode assembly 14 has a structure in which a sheet-like positive electrode 21 and a sheet-like negative electrode 22 are alternately stacked with a separator 23 interposed therebetween, so that they are layered. Have. The positive electrode 21 and the negative electrode 22 are insulated by a separator 23.

  The positive electrode 21 has a rectangular positive metal foil (for example, aluminum foil) and a positive electrode active material layer on both surfaces of the positive metal foil. The positive electrode 21 has a positive electrode tab 31 protruding from the end of the positive electrode 21. The negative electrode 22 has a rectangular negative metal foil (for example, copper foil) and negative electrode active material layers on both sides of the negative metal foil. The negative electrode 22 has a negative electrode tab 32 protruding from the end of the negative electrode 22.

  The electrode assembly 14 includes a positive electrode tab group 31a and a negative electrode tab group 32a. The positive electrode tab group 31 a and the negative electrode tab group 32 a protrude from the end surface 14 a facing the lid 13 in the electrode assembly 14. In the positive electrode tab group 31a, a plurality of positive electrode tabs 31 are stacked in layers. Similarly, in the negative electrode tab group 32a, a plurality of negative electrode tabs 32 are layered.

  As shown in FIG. 1 or FIG. 3, the secondary battery 10 includes a positive electrode conductive member 40 that electrically connects the positive electrode terminal 15 and the positive electrode tab group 31a. The positive electrode conductive member 40 is composed of a single metal plate (in this embodiment, an aluminum plate).

  The positive electrode conductive member 40 includes a first joint 41 disposed relatively closer to the lid 13, a second joint 42 disposed closer to the electrode assembly 14 than the first joint 41, and a first A curved third joint 43 that connects the joint 41 and the second joint 42. In the first joint portion 41, a positive electrode tab group 31 a is welded to a surface (lower surface) facing the end surface 14 a of the electrode assembly 14. Thereby, the 1st junction part 41 and the positive electrode tab group 31a are electrically connected.

  The positive terminal 15 is made of aluminum. Further, the positive electrode terminal 15 includes a positive electrode head portion 51 as a prismatic terminal head portion and a positive electrode shaft portion 52 as a columnar terminal shaft portion protruding from the seating surface 51 a of the positive electrode head portion 51. The positive electrode shaft portion 52 has a thread groove on the outer peripheral surface. The positive electrode shaft portion 52 protrudes to the outside of the case 11 through the through hole 13 b of the lid 13, and the positive electrode head portion 51 protrudes to the inside of the case 11. In the positive electrode terminal 15, assuming that the direction connecting the positive electrode head portion 51 and the positive electrode shaft portion 52 is an axial direction, the positive electrode terminal 15 has a screw hole 15 b that is recessed from the front end surface of the positive electrode shaft portion 52 in the axial direction.

  The secondary battery 10 includes an insulating O-ring 53 through which the positive electrode shaft portion 52 is inserted and supported by the seating surface 51 a of the positive electrode head portion 51. Further, the secondary battery 10 includes an insulating flanged ring 54 through which the positive electrode shaft portion 52 is inserted. The flanged ring 54 is a cylindrical member fitted into the through hole 13b.

  The secondary battery 10 has a nut 55 that is screwed onto the positive electrode shaft portion 52 from above the flanged ring 54. The positive electrode terminal 15 and the lid 13 are unitized by a nut 55 screwed onto the positive electrode shaft portion 52. The flanged ring 54 is interposed between the positive electrode shaft portion 52 and the peripheral edge portion of the through hole 13 b of the lid 13, and between the nut 55 and the lid 13.

  The positive electrode head 51 is disposed inside the case 11. A second joint portion 42 of the positive electrode conductive member 40 is welded to the surface of the positive electrode head portion 51 on the electrode assembly 14 side. Thereby, the positive electrode terminal 15 is electrically connected to the electrode assembly 14 via the positive electrode conductive member 40. The positive electrode terminal 15 and the positive electrode conductive member 40 are electrically connected, and the positive electrode conductive member 40 is electrically connected to the positive electrode tab group 31a, whereby the electrode assembly 14 and the positive electrode terminal 15 are electrically connected. An energization path between the connecting portions is configured.

  The secondary battery 10 includes an insulating first positive electrode insulating member 57 that covers the seating surface 51 a of the positive electrode head 51, and an insulating second positive electrode insulating member that is interposed between the positive electrode conductive member 40 and the electrode assembly 14. 58. The first positive electrode insulating member 57 regulates contact between the lid 13 and the positive electrode head 51. The first positive electrode insulating member 57 is attached to the positive electrode head portion 51 from the lid 13 side. The first positive electrode insulating member 57 covers the seating surface 51 a of the positive electrode head portion 51 and a part of the outer peripheral surface. The second positive electrode insulating member 58 regulates contact between the positive electrode conductive member 40 and the electrode assembly 14.

  The secondary battery 10 includes a negative electrode conductive member 60 that electrically connects the negative electrode terminal 16 and the negative electrode tab group 32a. The negative electrode conductive member 60 is composed of a single metal plate (a copper plate in the present embodiment). The negative electrode conductive member 60 is located between the lid 13 of the case 11 and the electrode assembly 14.

  The negative electrode conductive member 60 includes a first joint 61 disposed relatively closer to the lid 13, a second joint 62 disposed closer to the electrode assembly 14 than the first joint 61, and a first A curved third joining portion 63 that connects the joining portion 61 and the second joining portion 62; In the 1st junction part 61, the negative electrode tab group 32a is welded to the surface (lower surface) facing the end surface 14a of the electrode assembly 14, whereby the first junction part 61 and the negative electrode tab group 32a are electrically connected. It is connected.

  The negative terminal 16 is made of copper. Further, the negative electrode terminal 16 has a negative electrode head portion 71 as a cylindrical terminal head portion, and a negative electrode shaft portion 72 as a terminal shaft portion protruding from the seating surface 71 a of the negative electrode head portion 71. The negative electrode shaft portion 72 has a thread groove on the outer peripheral surface. The negative electrode shaft portion 72 protrudes outside the case 11 through the through hole 13 b of the lid 13. In the negative electrode terminal 16, assuming that the direction connecting the negative electrode head portion 71 and the negative electrode shaft portion 72 is the axial direction, the negative electrode terminal 16 is recessed from the tip end surface in the axial direction of the negative electrode shaft portion 72 and penetrates the negative electrode terminal 16 in the axial direction. And a screw hole 16c as a connection hole. A bus bar fastening bolt (not shown) can be screwed into the screw hole 16c. The bus bar fastening bolt is used to connect the bus bar to the electrode terminal when the electrode terminals of the secondary battery 10 are connected by the bus bar.

  The negative electrode head 71 is disposed inside the case 11. The negative electrode head 71 includes a terminal recess 71 c on the surface on the electrode assembly 14 side, and the terminal recess 71 c is recessed in a mortar shape from the electrode assembly 14 toward the lid 13. The negative electrode terminal 16 includes a tapered surface 71d on the outer peripheral surface surrounding the terminal recess 71c. The tapered surface 71 d gradually increases in width along the axial direction of the negative electrode terminal 16 from the terminal recess 71 c toward the negative electrode shaft portion 72.

  Further, the secondary battery 10 includes an insulating O-ring 73 that is inserted through the negative electrode shaft portion 72 and supported by the seat surface 71 a of the negative electrode head portion 71. The secondary battery 10 includes an insulating flanged ring 74 through which the negative electrode shaft portion 72 is inserted. The flanged ring 74 is a cylindrical member fitted into the through hole 13b. The secondary battery 10 includes a nut 75 screwed onto the negative electrode shaft portion 72 from above the flanged ring 74. The negative electrode terminal 16 and the lid 13 are unitized by a nut 75 screwed onto the negative electrode shaft portion 72. The flanged ring 74 is interposed between the negative electrode shaft portion 72 and the peripheral edge portion of the through hole 13 b of the lid 13 and between the nut 75 and the lid 13.

  The secondary battery 10 includes an insulating cover 87 that covers the seat surface 71a of the negative electrode head portion 71 and the tapered surface 71d. The cover 87 is cylindrical. The cover 87 includes a peripheral wall 87a that surrounds the outer peripheral surface of the negative electrode head portion 71, and a cover wall 87b that extends from the inner peripheral edge of the peripheral wall 87a toward the central axis of the peripheral wall 87a. In the cover 87, the inner surface of the lid wall 87b is supported by the seat surface 71a, and the inner peripheral surface of the peripheral wall 87a faces the tapered surface 71d. A lid wall 87 b is interposed between the lid 13 and the seat surface 71 a of the negative electrode head 71, and the lid wall 87 b regulates contact between the lid 13 and the negative electrode head 71.

  The secondary battery 10 includes a current interrupting unit 80 integrated with the negative electrode terminal 16 which is one of the electrode terminals. The current interrupting unit 80 is disposed inside the case 11, and electrically connects the electrode assembly 14 and the connection portion of the negative electrode terminal 16 when the internal pressure of the case 11 reaches a predetermined set pressure. Shut off the current in the current path. The current interrupting part 80 is located at a connection part between the negative electrode head part 71 of the negative electrode terminal 16 and the second joint part 62 of the negative electrode conductive member 60.

  In this embodiment, the negative electrode head 71 is electrically connected to the negative electrode conductive member 60 via the current interrupting portion 80, and the negative electrode conductive member 60 is electrically connected to the negative electrode tab group 32a. An energization path between the assembly 14 and the negative electrode terminal 16 is configured.

  When the current interrupting unit 80 is activated by the gas generated inside the case 11, the current interrupting unit 80 interrupts electrical connection between the negative electrode head 71 of the negative electrode terminal 16 and the negative electrode conductive member 60. That is, the current interrupting unit 80 constitutes a part of the energization path when not operating, and interrupts the energization path when operated under the pressure of the gas generated in the case 11. The current interrupting part 80 is provided integrally with the second joining part 62 of the negative electrode conductive member 60.

  The current interrupting part 80 has a contact plate 81 joined to the second joining part 62 and the negative electrode head 71. The contact plate 81 is made of a conductive material and has a bowl shape that protrudes toward the electrode assembly 14. The contact plate 81 covers the terminal recess 71c from the electrode assembly 14 side. The outer peripheral portion of the contact plate 81 that protrudes from the terminal concave portion 71c and the peripheral edge portion of the terminal concave portion 71c in the negative electrode head portion 71 are fixed by spot welding.

  The portion of the contact plate 81 that faces the terminal recess 71c is convex toward the electrode assembly 14 (downward) in the normal state, and the portion that is convex toward the electrode assembly 14 and the second joint The joint surface 62a of the part 62 is welded. A conductive portion that conducts the negative electrode head portion 71 of the negative electrode terminal 16 and the negative electrode conductive member 60 through a negative electrode welded portion P (a portion indicated by dot hatching in FIG. 3) that is a welded portion between the contact plate 81 and the second joint portion 62. And Therefore, the negative electrode conductive member 60 and the negative electrode terminal 16 are electrically connected via the contact plate 81. The second joint portion 62 has a disk shape, and the joint surface 62a has a circular shape. And the negative electrode welding part P is provided in the center part of the joining surface 62a.

  Since the contact plate 81 is bowl-shaped, the negative electrode head 71 is separated from the second joint 62 around the contact plate 81 by the amount of protrusion of the contact plate 81 from the negative electrode head 71. It is necessary to. Therefore, the current interrupting unit 80 includes an insulating ring 82 that is disposed between the negative electrode head portion 71 and the second joint portion 62. The insulating ring 82 is disposed on the outer peripheral side of the contact plate 81 and on the inner peripheral side of the tapered surface 71d, surrounds the peripheral portion of the contact plate 81, and holds the negative electrode head 71 and the negative electrode conductive member 60 at a predetermined interval. To do. The tapered surface 71 d is widened from the joint surface of the contact plate 81 in the negative electrode head 71 toward the negative electrode shaft portion 72.

  The negative electrode conductive member 60 has a blocking recess 60 c on the surface of the second joint 62 on the electrode assembly 14 side. The blocking recess 60 c is recessed in a mortar shape from the electrode assembly 14 toward the lid 13. The negative electrode weld portion P is located on the bottom surface of the blocking recess 60c. The 2nd junction part 62 has the fracture | rupture groove | channel 84 in the site | part used as the bottom face of the interruption | blocking recessed part 60c. The fracture groove 84 has an annular shape surrounding the negative electrode weld portion P. In addition, the second joint portion 62 includes a thin portion 84 a corresponding to the fracture groove 84. The thin portion 84 a is a portion where the thickness is made thinner than the portion other than the thin portion 84 a in the second joint portion 62 by forming the fracture groove 84 in the second joint portion 62. Therefore, the thin-walled portion 84 a is the same as the fracture groove 84 and has an annular shape provided around the negative electrode welded portion P.

  The current interrupting unit 80 includes a deformation plate 85 that receives the internal pressure of the case 11 and deforms. 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 joint portion 62. The deformation plate 85 has a disk shape and covers the blocking recess 60c from the electrode assembly 14 side. The outer peripheral portion of the deformable plate 85 and the second joint portion 62 are fixed by welding over the entire outer periphery of the deformable plate 85. The deformation plate 85 airtightly separates the inside of the case 11 from the outside of the case 11.

  The deformation plate 85 protrudes from the lid 13 side toward the electrode assembly 14 side (downward) in the normal state, and protrudes toward the lid 13 at a portion facing the negative electrode welded portion P in the convex portion. A protrusion 85a. The protrusion 85 a is made of an insulating material and faces the negative electrode welded portion P surrounded by the fracture groove 84.

  The current interrupting unit 80 includes a protection member 86 installed at a position closer to the electrode assembly 14 than the deformation plate 85. The protection member 86 is disposed between the deformation plate 85 and the electrode assembly 14. The protection member 86 prevents the deformation plate 85 from being deformed by an impact applied to the deformation plate 85. The protection member 86 has a disk shape, and a support recess 86 a that is recessed along the deformation plate 85 that is convex toward the electrode assembly 14 exists on the upper surface of the protection member 86. There is a gas hole 86b penetrating in the vertical direction on the bottom surface of the support recess 86a.

  The external pressure (substantially atmospheric pressure) of the case 11 acts on one surface (the surface on the lid 13 side) of the deformation plate 85 via the screw hole 16c. Further, the internal pressure of the case 11 acts on the other surface (surface on the electrode assembly 14 side) of the deformation plate 85 via the gas hole 86b. And the deformation | transformation board 85 is comprised so that it may deform | transform by pressure and may become convex toward the lid | cover 13, when the internal pressure larger than a setting pressure is provided to the surface at the side of the electrode assembly 14 side. .

  The secondary battery 10 includes a negative electrode head 71, a contact plate 81, an insulating ring 82, a negative electrode conductive member 60 (second joint portion 62), a deformation plate 85, and a caulking member 88 that unitizes the protection member 86.

  In the secondary battery 10 having the above-described configuration, the inner peripheral surface of the peripheral wall 87a of the cover 87, the tapered surface 71d of the negative electrode head portion 71, the outer peripheral surface of the insulating ring 82, and the second joint portion 62 of the negative electrode conductive member 60 are joined. A filling space S defined by the surface 62a is provided. The filling space S has an annular shape surrounding the tapered surface 71 d of the negative electrode head portion 71. The filling space S is tightly filled with the liquid gasket 76. In general, a liquid gasket is a substance that is fluid at normal temperature, and when applied to an application part, it cures after a certain period of time and maintains oil-tightness, water-tightness, and airtightness at the application part, thereby suppressing leakage.

  As the liquid gasket 76 of this embodiment, a silicone-based liquid gasket is used in consideration of resistance to the electrolytic solution. The silicone-based liquid gasket 76 has a property of being cured by moisture in the air when exposed to air in a fluid state and being cured without requiring heating, pressurization, or the like. The liquid gasket 76 includes an inner peripheral surface of the peripheral wall 87 a of the cover 87, a tapered surface 71 d of the negative electrode head portion 71, an outer peripheral surface of the insulating ring 82, and a joint surface 62 a of the second joint portion 62 of the negative electrode conductive member 60. The filling space S is filled without any gaps. Therefore, the liquid gasket 76 seals between the negative electrode head 71 and the negative electrode conductive member 60.

Next, a method for filling the liquid gasket 76 will be described.
First, although not shown, the outer peripheral portion of the deformation plate 85 is bonded to the second bonding portion 62 of the negative electrode conductive member 60. Next, the peripheral portion of the contact plate 81 is welded to the negative electrode head 71 while the contact plate 81 is disposed so as to cover the terminal recess 71 c of the negative electrode head 71.

  Then, as shown in FIG. 4, the cover 87 is set on the jig 77 so that the cover wall 87b of the cover 87 is below the peripheral wall 87a. Next, the seat surface 71a of the negative electrode head 71 is supported on the inner bottom surface of the cover wall 87b while the negative electrode shaft portion 72 is passed through the cover wall 87b of the cover 87. In this state, the negative electrode head 71 is accommodated in the peripheral wall 87a, and the taper surface 71d of the negative electrode head 71 is opposed to the inner peripheral surface of the peripheral wall 87a, and a gap S1 is formed.

  Next, an insulating ring 82 is disposed around the contact plate 81 joined to the negative electrode head portion 71 and on the inner peripheral side from the tapered surface 71d. Then, the air gap S1 is defined by the inner peripheral surface of the peripheral wall 87a, the tapered surface 71d of the negative electrode head 71, and the outer peripheral surface of the insulating ring 82. The gap S1 opens upward, and the opening is widest. The gap S1 gradually decreases with the inclination of the tapered surface 71d as it goes downward along the axial direction of the negative electrode terminal 16.

  And the liquid gasket 76 with fluidity | liquidity is filled into space | gap S1. Finally, the contact plate 81 is covered with the second joint portion 62 of the negative electrode conductive member 60, and the contact plate 81 and the second joint portion 62 are welded. Then, the gap S <b> 1 is closed by the second joint portion 62, the filling space S is defined, and the liquid gasket 76 is sealed in the filling space S.

Next, the operation of the secondary battery 10 will be described.
In the secondary battery 10, when gas is generated in the electrode assembly 14 during overcharge / overdischarge, the internal pressure of the case 11 increases. When the internal pressure reaches the set pressure, the deformed plate 85 receiving the pressure is deformed so as to be convex toward the negative electrode welded portion P. Then, the protrusion 85 a collides with the negative electrode welded portion P surrounded by the fracture groove 84, the negative electrode welded portion P of the negative electrode conductive member 60 is broken, and the contact plate 81 is deformed toward the lid 13. As a result, the contact plate 81 and the negative electrode conductive member 60 are separated from each other, so that the electrical connection between the negative electrode conductive member 60 and the negative electrode terminal 16 is physically interrupted, and the electrode assembly 14 and the negative electrode terminal 16 are disconnected. The current flowing between them is interrupted.

  Here, a large voltage may be applied between the second joint portion 62 of the negative electrode conductive member 60 and the negative electrode head portion 71. At this time, the liquid gasket 76 is filled between the second joint portion 62 and the negative electrode head portion 71, and the electrolyte solution is suppressed from entering between the second joint portion 62 and the negative electrode head portion 71. Yes. For this reason, it is suppressed that the 2nd junction part 62 and the negative electrode head 71 short-circuit via electrolyte solution (liquid junction).

Therefore, according to the present embodiment, the following effects can be obtained.
(1) The filling space S surrounding the tapered surface 71 d of the negative electrode terminal 16 is filled with the liquid gasket 76. The liquid gasket 76 extends throughout the filling space S and is in close contact with the tapered surface 71d, the inner peripheral surface of the peripheral wall 87a of the cover 87, the joint surface 62a of the second joint 62, and the outer peripheral surface of the insulating ring 82. Therefore, the liquid gasket 76 prevents the electrolyte from entering the filling space S, and the negative electrode terminal 16 and the negative electrode conductive member 60 are insulated by the liquid gasket 76. Therefore, even when a large voltage is applied to the negative electrode terminal 16 and the negative electrode conductive member 60 in a state where the current conduction between the negative electrode conductive member 60 and the negative electrode terminal 16 is interrupted by the operation of the current interruption unit 80, the liquid gasket 76 The liquid junction between the negative electrode terminal 16 and the negative electrode conductive member 60 is suppressed, and re-energization between the negative electrode terminal 16 and the negative electrode conductive member 60 is suppressed.

  (2) The liquid gasket 76 is a silicone type. Since the silicone-based liquid gasket has electrolyte solution resistance, the liquid gasket 76 is hardly deteriorated by the electrolyte solution, and the sealed state by the liquid gasket 76 can be maintained.

  (3) The insulating ring 82 is disposed between the negative electrode head 71 and the negative electrode conductive member 60. For this reason, the filling space S can be partitioned on the inner peripheral side of the tapered surface 71d, and the negative electrode head 71 and the negative electrode conductive member 60 are easily separated by a predetermined interval even before the liquid gasket 76 is cured. Can be held in.

In addition, you may change the said embodiment as follows.
In addition to the liquid gasket 76, an O-ring may be provided in the filling space S. The O-ring may be at least in close contact with the tapered surface 71d and the joining surface 62a, and the outer peripheral surface of the O-ring may be in close contact with the inner peripheral surface of the peripheral wall 87a in the cover 87. The liquid gasket 76 is filled in a gap existing in the filling space S around the O-ring. For example, when only the O-ring is disposed in the filling space S, the diameter may be reduced due to deterioration of the O-ring, and the outer peripheral surface of the O-ring may be separated from the inner peripheral surface of the peripheral wall 87a. At this time, there is a possibility that the negative electrode head 71 and the second joint 62 may be in liquid junction.

  However, by filling the filling space S with the liquid gasket 76 in addition to the O-ring, the insulation between the negative electrode head 71 and the second joint portion 62 is maintained by the liquid gasket 76 even when the O-ring is deteriorated. Can be suppressed.

  O Although it has the insulating ring 82 in embodiment, it is not restricted to this. For example, the shape of the negative electrode terminal 16 facing the joint surface 62a of the second joint portion 62 is formed such that a gap is provided between the negative electrode head portion 71 and the second joint portion 62, and the gap causes the negative electrode head portion to be formed. As long as 71 and the second joint portion 62 are insulated, the insulating ring 82 may be omitted. Specifically, the peripheral wall 87 a of the cover 87 may hold the second joint 62 in a state of being separated from the negative electrode head 71. Alternatively, the insulating ring 82 may be configured by an O-ring or the like.

As the liquid gasket 76, a material other than the silicone type may be used, and a phenol type, a modified ester type, an acrylic type, an aqueous acrylic type, or the like may be used.
In the negative electrode head 71, the outer peripheral surface that divides the filling space S may not be tapered and may be changed as appropriate.

  In the embodiment, the cover 87 includes the peripheral wall 87a and the lid wall 87b, but the peripheral wall 87a and the lid wall 87b may be separated. In the embodiment, the cover 87 is insulative, but is not limited thereto. For example, what is necessary is just to insulate between the negative electrode head 71 and the negative electrode electrically-conductive member 60, and between the seat surface 71a of the negative electrode head 71 by other members.

  In the embodiment, the nut 55 is screwed to the positive electrode shaft portion 52 so that the positive electrode terminal 15 is fixed to the lid 13. However, the present invention is not limited to this. For example, the positive electrode terminal 15 may be fixed to the lid 13 by caulking a part of the positive electrode shaft portion 52. Similarly, for example, the negative electrode terminal 16 may be fixed to the lid 13 by caulking a part of the negative electrode shaft portion 72.

  In the embodiment, when connecting the electrode terminal and the bus bar, the bus bar fastening bolt is screwed into the screw hole 16c of the electrode terminal. However, the bus bar and the electrode terminal are connected by fitting or rivet. It may be. For example, a connecting member that includes a head and a fitting shaft extending from the head is employed. The electrode terminal includes a fitting hole instead of the screw hole 16c as a connection hole. Then, the bus bar may be connected to the electrode terminal by fitting the fitting shaft portion of the connecting member into the fitting hole.

  The power storage device can also be applied to a secondary battery having a current interrupting unit 80 that is integral with the positive electrode terminal 15. In this case, the positive terminal 15 is provided with a screw hole that penetrates the positive terminal 15 in the axial direction as a connection hole.

The power storage device can also be applied to power storage devices other than secondary batteries, such as capacitors.
The positive electrode 21 and the negative electrode 22 may have a structure in which an active material is present on one side of a metal foil.

  The secondary battery 10 may be a lithium ion secondary battery or another secondary battery. In short, any ion may be used as long as ions move between the active material for the positive electrode and the active material for the negative electrode and charge is transferred.

The electrode assembly 14 is not limited to the laminated type, and may be a wound type in which a belt-like positive electrode and a belt-like negative electrode are wound and laminated in layers.
Next, the technical idea that can be grasped from the above embodiment and other examples will be described below.

  (A) The electrode assembly is a power storage device in which a sheet-like positive electrode and a sheet-like negative electrode are alternately stacked with a separator interposed therebetween.

  DESCRIPTION OF SYMBOLS S ... Filling space, 10 ... Secondary battery as an electrical storage device, 11 ... Case, 13 ... Lid as wall part, 14 ... Electrode assembly, 14a ... End surface, 15 ... Positive electrode terminal as an electrode terminal, 16 ... One side Negative electrode terminal as electrode terminal, 16c ... Screw hole as connecting hole, 40 ... Positive electrode conductive member as conductive member, 60 ... Negative electrode conductive member as conductive member, 62a ... Joint surface, 71 ... Negative electrode head as terminal head 71a ... seating surface, 71d ... taper surface, 72 ... negative electrode shaft portion as terminal shaft portion, 76 ... liquid gasket, 80 ... current interrupting portion, 81 ... contact plate, 82 ... insulating ring, 87 ... cover.

Claims (4)

A pair of electrode terminals fixed to a wall facing the end face of the electrode assembly in the case;
A conductive member connecting the electrode assembly and the electrode terminal in the case;
A power storage device comprising: a current interrupting unit that interrupts an energization path between one electrode terminal and the electrode assembly when the internal pressure of the case exceeds a set pressure;
The one electrode terminal is erected from a terminal head electrically connected to the conductive member in the case and a seating surface of the terminal head, and protrudes out of the case through the wall. And a connecting hole penetrating in the axial direction connecting the terminal shaft portion and the terminal head,
The current interrupting unit is
The connecting hole has a hook shape that is convex toward the conductive member in a state of covering the opening at the terminal head, and the outer peripheral portion is joined to the terminal head and is convex toward the conductive member. A contact plate in which the portion to be joined to the joining surface of the conductive member;
A cylindrical cover surrounding the outer peripheral surface of the terminal head,
The outer peripheral surface of the terminal head is a tapered surface,
An insulating ring is disposed between the terminal head and the conductive member;
It has a liquid gasket filled in a filling space surrounded by the outer peripheral surface of the terminal head, the inner peripheral surface of the cover, the joint surface of the conductive member, and the outer peripheral surface of the insulating ring. A power storage device.   The power storage device according to claim 1, wherein the liquid gasket is of a silicone type. The insulating ring, while being placed between the terminal head and the conductive member in a state surrounding the periphery of the contact plate, the outer peripheral surface of the insulating ring facing the filling space, the filling space 3. The power storage device according to claim 1, wherein an outer peripheral surface of the terminal head that faces is a tapered surface that is widened toward the terminal shaft along the axial direction.   The power storage device according to any one of claims 1 to 3, wherein the power storage device is a secondary battery.

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