JP2016054022A - Power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage device which enables the suppression of gas penetration from the inside of a case into to a current interrupt part.SOLUTION: A secondary battery 10 comprises: a case in which an electrode assembly is enclosed; a conduction part (negative electrode welded part P) electrically connecting between a negative electrode terminal 16 provided on the case and a negative electrode conductive member 60 connected to the electrode assembly; and a current interrupt part 80 having a structure arranged so that the negative electrode welded part P is broken by deformation of a deformable plate 85 accompanying the rise in an inside pressure of the case. The inside pressure of the case acts on one face of the deformable plate 85, whereas a pressure different from the inside pressure of the case acts on the other face. The secondary battery 10 further comprises: a protection film 90 covering a superposing portion of the negative electrode terminal 16 and the current interrupt part 80. The protection film 90 has opening parts 91 and 92; the inner edge of each opening part is put in close contact with an opposed face of the covered part.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a power storage device including a current interrupting unit that interrupts a current when an abnormality occurs.

  A vehicle such as an EV (Electric Vehicle) or a PHV (Plug in Hybrid Vehicle) is equipped with a secondary battery such as a lithium ion battery as a power storage device that stores power supplied to an electric motor serving as a prime mover. The secondary battery includes an electrode assembly in which a positive electrode, a negative electrode, and a separator that insulates the electrodes form a layered structure, and a case that houses the electrode assembly.

  2. Description of the Related Art Conventionally, there is a secondary battery having a current interrupting unit that interrupts current when an abnormality occurs during overcharging (for example, Patent Document 1). This current interruption part has a deformation plate as a diaphragm. The deformable plate has a disc shape convex toward the side away from the inner surface of the case, and the internal pressure of the case acts on one surface and a pressure different from the internal pressure on the other surface. Pressure) is acting.

  In such a secondary battery, when the internal pressure of the case becomes high at the time of abnormality, the deformation plate is deformed by receiving the pressure on the other surface, and the deformation plate becomes a convex shape on the case inner surface side. Along with this, the conduction portion that conducts the electrode terminal provided in the case and the conductive member connected to the electrode assembly is broken, and the current of the secondary battery is cut off.

JP 2014-17051 A

  The secondary battery of Patent Document 1 has a structure in which the current interrupting unit is activated by a difference in pressure acting on both surfaces of the deformation plate. And if the inside of a current interruption part is not sealed from the inside of a case, the internal pressure of a case will act on both surfaces of a deformation | transformation board, and it will become impossible to operate a current interruption part.

  This invention was made paying attention to the problem which exists in the said prior art, The objective is providing the electrical storage apparatus which can suppress the gas penetration | invasion from the inside of a case to the inside of an electric current interruption part. It is in.

  A power storage device for achieving the above object includes: an electrode assembly; a case that accommodates the electrode assembly; an electrode terminal provided in the case; and a conductive member connected to the electrode assembly. Part. In addition, the conductive portion is provided with a deforming plate on which the internal pressure of the case acts on one surface and a pressure different from the internal pressure acts on the other surface, and the deformation plate deforms as the internal pressure increases. The power storage device has a current interrupting portion having a structure for breaking the battery. Furthermore, the power storage device is a protective film that covers at least the joining portion of the current interrupting portion and the electrode terminal, and the inner edge of the opening connecting the inner surface and the outer surface is in close contact with the inner edge and the opposing surface. Has a protective film.

According to the power storage device, by covering the mating portion between the current interrupting portion and the electrode terminal with the protective film, it is possible to seal the gas intrusion into the current interrupting portion from the inside of the case.
In the above power storage device, it is preferable that the protective film has a bag shape that covers the entire joining portion of the current interrupting portion and the electrode terminal.

  According to the power storage device described above, the number of openings that connect the inner surface and the outer surface of the protective film can be reduced, so that the seal by the close contact between the protective film and the opposing surface can be easily realized.

In the above power storage device, the protective film is preferably made of a material that thermally contracts.
According to the above power storage device, when the protective film is assembled, the protective film is disposed and then heated and thermally contracted, so that the protective film can be deformed and attached in accordance with the outer surface shape.

In the power storage device, the pressure different from the internal pressure is a pressure lower than the atmospheric pressure enclosed in the current interrupting unit.
According to the power storage device, when the current interrupting unit is not in operation, the internal pressure of the current interrupting unit (specifically, the portion covered with the protective film) can be made lower than the external pressure of the part. As a result, the protective film can be attracted to the current interrupting portion side by this pressure difference and can be suitably brought into close contact with the opposing surface, and the sealing function of the protective film can be improved.

  A secondary battery can be employed as the power storage device.

  According to the present invention, gas intrusion from the inside of the case to the inside of the current interrupting portion can be suppressed.

The perspective view of the secondary battery of one Embodiment. The exploded perspective view of an electrode assembly. The exploded perspective view of a secondary battery. The top view of a conductive member and a terminal. The disassembled perspective view which shows the joining structure of an electroconductive member and a terminal. FIG. 6 is a sectional view taken along line 6-6 in FIG. Sectional drawing which expands and shows the negative electrode terminal periphery.

Hereinafter, an embodiment of a power storage device will be described with reference to FIGS.
As shown in FIG. 1, a secondary battery 10 as a power storage device includes a rectangular parallelepiped case 11. The case 11 includes a bottomed box-shaped case main body 12 that is open on one side, and a rectangular flat lid 13 that closes the opening of the case main body 12. The case body 12 and the lid 13 are joined by welding or the like.

  The secondary battery 10 includes an electrode assembly 14 and an electrolytic solution (not shown) accommodated in the case 11, and a positive electrode terminal 15 and a negative electrode terminal 16 as electrode terminals that exchange power with the electrode assembly 14. ing. Each terminal 15, 16 is located on the lid 13 of the case 11 and is disposed in a state of penetrating the lid 13. The terminals 15 and 16 are exposed to the outside from the case 11. In addition, the secondary battery 10 of this embodiment is a lithium ion battery, for example.

  As shown in FIG. 2, the electrode assembly 14 has a structure in which positive electrodes 21 and negative electrodes 22 are alternately stacked via separators 23, which are porous films through which ions related to electrical conduction can pass. Each of the electrodes 21 and 22 and the separator 23 is a rectangular sheet.

  The positive electrode 21 includes a rectangular positive metal foil (for example, an aluminum foil) 21a and positive electrode active material layers 21b on both surfaces of the positive metal foil 21a. The negative electrode 22 includes a rectangular negative metal foil (for example, copper foil) 22a and negative electrode active material layers 22b on both surfaces of the negative metal foil 22a.

  The positive electrode 21 has a positive electrode tab 31 having a shape protruding from the end 21 c of the positive electrode 21. Similarly, the negative electrode 22 has a negative electrode tab 32 having a shape protruding from the end 22 c of the negative electrode 22. The electrodes 21 and 22 are stacked so that the same polarities of the tabs 31 and 32 are arranged in a row.

  As shown in FIG. 3, the negative electrode tabs 32 are gathered together in one of the stacking directions of the electrodes 21, 22 and folded back to the other in the gathered state. Similarly, each positive electrode tab 31 is folded back to the other in a state where the positive electrode tabs 31 are gathered close to one of the electrodes 21 and 22 in the stacking direction.

Here, in the following description, for convenience, the direction connecting the electrode assembly 14 and the lid 13 is defined as the vertical direction.
As shown in FIGS. 3 and 4, the secondary battery 10 includes a positive electrode conductive member 40 that is used to electrically connect the positive electrode tab 31 and the positive electrode terminal 15. The positive electrode conductive member 40 is composed of a single metal plate, for example, an aluminum plate. The positive electrode conductive member 40 exists between the lid 13 of the case 11 and the electrode assembly 14 in the vertical direction, and is joined to both the positive electrode tab 31 and the positive electrode terminal 15.

  As shown in FIG. 5 and FIG. 6, the positive electrode terminal 15 has a prismatic positive electrode head portion 51, and a positive electrode shaft portion that extends upward from the upper surface 51 a of the positive electrode head portion 51 and has a thread groove on the outer peripheral surface. 52.

  As shown in FIG. 6, the positive electrode shaft portion 52 protrudes outside the case 11 through the through hole 13 b provided in the lid 13. An insulating O-ring 53 and an insulating flanged ring 54 that fits into the through hole 13 b are inserted through the positive electrode shaft 52. A nut 55 is screwed onto the positive shaft 52 from above the flanged ring 54, and the positive terminal 15 and the lid 13 are unitized. 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 exists in the case 11. On the lower surface 51 b of the positive electrode head 51, there is a positive electrode weld piece 56 that protrudes from the lower surface 51 b toward the electrode assembly 14. The positive electrode conductive member 40 has a weld hole 40 a that can be fitted to the positive electrode weld piece 56. And it welds in the state which the positive electrode welding piece 56 of the positive electrode head 51 and the peripheral part of the welding hole 40a of the positive electrode electrically-conductive member 40 fitted. Thereby, the positive electrode conductive member 40 and the positive electrode terminal 15 are electrically connected.

  As shown in FIGS. 5 and 6, the secondary battery 10 includes an insulating first positive electrode insulating member 57 that covers a part of the positive electrode head 51, and a positive electrode conductive member 40 and an electrode assembly 14. Insulating second positive electrode insulating member 58 is provided. The first positive electrode insulating member 57 regulates the contact between the lid 13 and the positive electrode head 51, and is attached to the positive electrode head 51 from above, and the upper surface 51 a of the positive electrode head 51 and the positive electrode head 51. It covers 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 positive electrode weld piece 56 and the electrode assembly 14. The second positive electrode insulating member 58 has a rectangular plate-like base portion 58 a and four locking claws 58 b that stand from the base portion 58 a toward the positive electrode conductive member 40. The locking claw 58 b is locked to a portion of the positive electrode conductive member 40 that protrudes from the outer peripheral surface of the positive electrode head 51.

  As shown in FIG. 3, the secondary battery 10 includes a negative electrode conductive member 60 that is used to electrically connect the negative electrode tab 32 and the negative electrode terminal 16. The negative electrode conductive member 60 is composed of a single metal plate, for example, a copper plate. The negative electrode conductive member 60 exists between the lid 13 of the case 11 and the electrode assembly 14, and is bonded to both the negative electrode tab 32 and the current interrupting unit 80 integrated with the negative electrode terminal 16.

As shown in FIGS. 5 and 6, the negative electrode terminal 16 includes a negative electrode head portion 71 and a negative electrode shaft portion 72 that extends upward from the upper surface 71 a of the negative electrode head portion 71 and has a thread groove on the outer peripheral surface. Yes.
As shown in FIG. 6, the negative electrode shaft portion 72 protrudes outside the case 11 through the through hole 13 b provided in the lid 13. An insulating O-ring 73 and an insulating flanged ring 74 that fits into the through hole 13 b are inserted through the negative electrode shaft portion 72. A nut 75 is screwed onto the negative electrode shaft portion 72 from above the flanged ring 74, and the negative electrode terminal 16 and the lid 13 are unitized. The flanged ring 74 is interposed between the negative electrode shaft portion 72 and the peripheral edge portion of the through hole 13b of the lid 13 and between the nut 75 and the lid 13.

  The negative electrode head 71 exists in the case 11. On the lower surface 71 b of the negative electrode head 71, there is a terminal recess 71 c that is recessed in a mortar shape toward the lid 13. The negative electrode terminal 16 has a through hole 16a. The through hole 16a penetrates the negative electrode terminal 16 in the axial direction (vertical direction). The terminal recess 71c communicates with the outside of the case 11 through the through hole 16a.

  The current interrupting unit 80 is disposed between the negative electrode terminal 16 and the electrode assembly 14 in the vertical direction. The current interrupting unit 80 electrically connects the negative electrode terminal 16 and the negative electrode conductive member 60, and when the pressure in the case 11 exceeds a specified pressure, the electric current interrupting unit 80 electrically connects the negative electrode terminal 16 and the negative electrode conductive member 60. Block connections. That is, when the pressure in the case 11 is equal to or lower than the specified pressure, the current interrupting unit 80 constitutes a part of the conduction path between the negative electrode terminal 16 and the negative electrode tab 32, while the pressure in the case 11 exceeds the specified pressure. In such a case, the energization path is interrupted.

  As shown in FIG. 6, the current interrupting unit 80 includes a contact plate 81 joined to the upper surface 60 a of the negative electrode conductive member 60 and the lower surface 71 b of the negative electrode head portion 71. The contact plate 81 is a diaphragm made of a conductive material. The contact plate 81 has a disk shape and covers the terminal recess 71c by overlapping from below. The outer peripheral portion of the contact plate 81 protruding from the terminal concave portion 71c and the peripheral portion of the terminal concave portion 71c on the lower surface 71b of the negative electrode head portion 71 are fixed by spot welding. Therefore, the portion of the secondary battery 10 closer to the lid 13 than the contact plate 81 and the portion closer to the electrode assembly 14 than the contact plate 81 communicate with each other through the gap between the contact plate 81 and the negative electrode head 71. ing.

  A portion of the contact plate 81 facing the terminal recess 71 c in the vertical direction is convex toward the electrode assembly 14 (downward) in the normal state, and the protruding end of this convex portion and the upper surface 60 a of the negative electrode conductive member 60 are welded. Has been. As a result, the negative electrode welded portion P (the portion indicated by dot hatching in FIG. 6) that is a welded portion between the contact plate 81 and the negative electrode conductive member 60 is used as a conductive portion that conducts the negative electrode terminal 16 and the negative electrode conductive member 60. The conductive member 60 and the negative electrode head 71 are electrically connected via the contact plate 81.

  An insulating ring 82 is provided outside the outer periphery of the contact plate 81, and the insulating ring 82 exists between the upper surface 60 a of the negative electrode conductive member 60 and the lower surface 71 b of the negative electrode head 71. By this insulating ring 82, the lower surface 71 b of the negative electrode terminal 16 and the upper surface 60 a of the negative electrode conductive member 60 are arranged with a space therebetween. The contact plate 81 is supported by sandwiching the insulating ring 82 and the lower surface 71 b of the negative electrode head 71.

  On the lower surface 60 b of the negative electrode conductive member 60, there is a blocking recess 60 c that is recessed in a mortar shape from the electrode assembly 14 toward the lid 13. The bottom surface of the blocking recess 60c includes a negative electrode welded portion P as viewed from above. A fracture groove 84 surrounding the negative electrode welded portion P exists on the bottom surface of the blocking recess 60c. The breaking groove 84 has an annular shape, for example.

  The current interrupting unit 80 includes a deforming plate 85 that is deformed by the pressure in the case 11. The deformation plate 85 is a diaphragm made of an elastic material, for example, a metal plate, and is disposed below the negative electrode conductive member 60. The deformation plate 85 has a disk shape and covers the blocking recess 60c by overlapping from below, and the outer peripheral portion of the deformation plate 85 and the lower surface 60b of the negative electrode conductive member 60 are all of the outer peripheral portion of the deformation plate 85. It is fixed by welding over the circumference. The deformation plate 85 has a shape that seals the inside of the case 11 from the outside of the case 11 (specifically, a portion of the current interrupting portion 80 on the lid 13 side of the deformation plate 85).

  The deformation plate 85 is convex toward the electrode assembly 14 side (downward) in the normal state, and is a protrusion protruding upward at a position facing the negative electrode welded portion P in the convex portion in the vertical direction. There is 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 deformation plate 85 is configured to be deformed by the same pressure and protrude upwardly when a pressure larger than a specified pressure is applied from below to above.

  The current interrupting unit 80 includes a protection member 86 installed below the deformation plate 85. The protection member 86 is disposed between the deformation plate 85 and the electrode assembly 14 in the vertical direction. The protective member 86 prevents the deformation plate 85 from being deformed before an impact or the like is applied to the deformation plate 85 and the above-mentioned specified pressure is reached. The protection member 86 has a disk shape, and a support recess 86a that is recessed along the deformed plate 85 that protrudes downward exists on the upper surface of the protection member 86. A gas hole 86b penetrating in the vertical direction is present at a position facing the protrusion 85a on the bottom surface of the support recess 86a. In the present embodiment, the current interrupting unit 80 includes a contact plate 81 and a deformation plate 85. In the present embodiment, the negative electrode head 71, the negative electrode conductive member 60, the contact plate 81, the insulating ring 82, and the deformation plate 85 are stacked in the vertical direction. And the outer peripheral surface of the laminated body is comprised from the negative electrode head 71, the insulating ring 82, and the negative electrode electrically-conductive member 60, and the lower surface of the laminated body is comprised from the deformation | transformation board 85. FIG.

  As shown in FIG. 5 to FIG. 7, the secondary battery 10 is insulated from the mating portion of the negative electrode head portion 71 of the negative electrode terminal 16 and the current interrupting portion 80 (contact plate 81 and deformation plate 85), that is, the negative electrode conductive member 60. A protective film 90 is provided to cover the portion where the ring 82 overlaps and the portion where the negative electrode head 71 and the insulating ring 82 overlap. The protective film 90 is made of a heat-shrinkable material and has a bag shape that covers the negative electrode head 71 and the entire peripheral surface of the laminate.

  The protective film 90 includes a first opening portion 91 through which the negative electrode shaft portion 72 of the negative electrode terminal 16 is inserted, and a second opening portion 92 through which the negative electrode conductive member 60 is inserted. The inner edge of the first opening portion 91 is welded and adhered to the upper surface 71a of the negative electrode head portion 71 as an opposing surface over the entire circumference of the negative electrode shaft portion 72. Further, the inner edge of the second opening portion 92 is welded and adhered to the outer surface of the negative electrode conductive member 60 as the opposing surface over the entire circumference of the negative electrode conductive member 60. As a result, in the secondary battery 10, the gas in the case 11 enters the current interrupting portion 80 via the first opening 91 and the second opening 92 of the protective film 90 and is sealed.

  In the secondary battery 10, air outside the case 11 enters the current interrupting part 80 through the gap between the negative electrode terminal 16 and the contact plate 81 and the through hole 16 a of the negative electrode terminal 16. The pressure outside the case 11 (substantially atmospheric pressure) acts on one surface (the surface on the lid 13 side). Further, the internal pressure of the case 11 acts on the other surface of the deformation plate 85 (the surface on the electrode assembly 14 side) via the gas hole 86b and the like.

  When the internal pressure of the case 11 exceeds the specified pressure, the deformation plate 85 is deformed so as to protrude upward as shown by a two-dot chain line in FIGS. Then, the protrusion 85a 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 so as to protrude upward. To do. 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.

  As shown in FIGS. 5 to 7, the secondary battery 10 includes an insulative negative electrode insulating member 87, a negative electrode head 71, a contact plate 81, an insulating ring 82, a negative electrode that covers the upper surface 71 a and the outer peripheral surface of the negative electrode head 71. A caulking member 88 that unitizes the conductive member 60, the deformable plate 85, the protective member 86, and the protective film 90 is provided.

  The negative electrode insulating member 87 is attached to the negative electrode head 71 from above and regulates the contact between the lid 13 and the negative electrode head 71. Specifically, as shown in FIGS. 5 and 7, the negative electrode insulating member 87 has a cylindrical portion 87a and a flange portion 87b that extends radially inward at the upper end portion in the axial direction of the cylindrical portion 87a. The flange portion 87 b covers the upper surface 71 a of the negative electrode head portion 71, and the cylindrical portion 87 a covers the outer peripheral surface of the negative electrode head portion 71.

  The caulking member 88 includes a cylindrical portion 88a, and an upper collar portion 88b and a lower collar portion 88c that are at both ends in the axial direction of the cylindrical portion 88a and extend radially inward. The caulking member 88 is configured such that the upper collar portion 88 b is engaged with the negative electrode insulating member 87 and the lower collar portion 88 c is engaged with the stepped portion existing on the outer peripheral surface of the protective member 86, thereby It has become.

  Incidentally, the first relief recess 87 c exists at a position overlapping the negative electrode conductive member 60 when viewed from above at the lower end portion in the axial direction of the cylindrical portion 87 a of the negative electrode insulating member 87. Similarly, a second relief recess 88d exists at a position overlapping the negative electrode conductive member 60 when viewed from above at the lower end portion in the axial direction of the cylindrical portion 88a of the caulking member 88. Interference between the negative electrode insulating member 87 and the caulking member 88 and the negative electrode conductive member 60 is avoided by the relief recesses 87c and 88d.

  As shown in FIG. 3, the secondary battery 10 includes an insulating cover 100 disposed between the positive electrode conductive member 40 and the negative electrode conductive member 60 and the lid 13. The insulating cover 100 is made of, for example, an insulating resin material. As shown in FIG. 6, the insulating cover 100 is disposed across the positive electrode conductive member 40 and the negative electrode conductive member 60. One end of the insulating cover 100 in the longitudinal direction hits the outer peripheral surface of the caulking member 88, and the other end hits the outer peripheral surface of the first positive electrode insulating member 57. The lower surface of the insulating cover 100 is in contact with both the positive electrode conductive member 40 and the negative electrode conductive member 60.

Hereinafter, a procedure for unitization around the negative electrode terminal 16 will be briefly described.
As shown in FIGS. 5 to 7, first, an insulating ring 82 is sandwiched between the negative electrode conductive member 60 to which the deformation plate 85 is fixed and the negative electrode head portion 71 of the negative electrode terminal 16 to which the contact plate 81 is fixed. The deformable plate 85, the negative electrode conductive member 60, the contact plate 81, the negative electrode terminal 16, and the insulating ring 82 are assembled together.

  In this state, the negative electrode terminal 16 and the current blocking unit 80 are protected through the first opening 91 while the negative electrode conductive member 60 is inserted into the second opening 92 of the protective film 90 from the inside of the protective film 90. The negative electrode head 71 of the negative electrode terminal 16 and the current interrupting unit 80 are disposed inside the protective film 90 so as to be accommodated inside the protective film 90.

  Thereafter, the protective film 90 is heated. As a result, the protective film 90 is thermally shrunk to a shape along the outer surface of the negative electrode head 71 of the negative electrode terminal 16 and the outer surface of the laminate of the current interrupting unit 80. Further, the inner edge of the first opening portion 91 of the protective film 90 is welded to the outer surface of the negative electrode head portion 71, and the inner edge of the second opening portion 92 is welded to the outer surface of the negative electrode conductive member 60. FIG. 5 shows the protective film 90 having a shape after being thermally contracted by heating.

  Thereafter, the negative electrode insulating member 87 is attached to the negative electrode head 71 covered with the protective film 90, and the protective member 86 is provided at a position covering the deformation plate 85 covered with the protective film 90. The caulking member 88 is connected to the surface of the negative electrode insulating member 87 on the lid 13 side and the electrode of the protective member 86 so that the negative electrode head portion 71 and the current interrupting portion 80 are sandwiched between the negative electrode insulating member 87 and the protective member 86. It is attached in such a manner that it is locked to the surface on the assembly 14 side.

According to the present embodiment, the following effects can be obtained.
(1) By covering the mating portion of the negative electrode head portion 71 of the negative electrode terminal 16 and the current interrupting portion 80 with the protective film 90, it is possible to suppress gas intrusion from the case 11 into the current interrupting portion 80. it can. Therefore, not the pressure inside the case 11 but the pressure outside the case 11 can be applied to one surface of the deformation plate 85, and the current interrupting unit 80 can be appropriately operated.

  It is also possible to suppress the intrusion of gas from inside the case 11 into the current interrupting portion 80 by providing an O-ring between the negative electrode terminal 16 and the negative electrode conductive member 60. However, in a seal structure using an O-ring, since the O-ring needs to be disposed in a compressed state in order to increase the contact pressure of the O-ring contact surface, the structure is likely to be complicated. In this regard, in the secondary battery 10 of the present embodiment, it is possible to seal the gas intrusion from the case 11 into the current interrupting unit 80 without using an O-ring.

  Moreover, since gas is generated inside the case 11 when the secondary battery 10 is used, the internal pressure of the case 11 is higher than atmospheric pressure. In the secondary battery 10, the internal pressure of the case 11 acts on the outer surface of the protective film 90. Therefore, there is a difference between a pressure higher than the atmospheric pressure acting on the outer surface of the protective film 90 and the substantially atmospheric pressure acting on the inner surface of the protective film 90. In the secondary battery 10, the protective film 90 can be brought into close contact with the current interrupting part 80 side by this pressure difference, and thus the sealing function of the protective film 90 can be improved.

  (2) By forming the protective film 90 into a bag shape that covers not only the joining part of the negative electrode head 71 and the current interrupting unit 80 but also the entire negative electrode head 71 and the current interrupting unit 80, the protective film 90 includes There are only two openings for projecting the negative electrode shaft portion 72 and the negative electrode conductive member 60 from the protective film 90. For this reason, the number of openings that connect the inner surface and the outer surface of the protective film 90 can be reduced, and the number of locations where the protective film 90 and its opposing surface are welded can be reduced. Sealing by surface adhesion can be easily realized. In addition, since the deformable plate 85 is accommodated inside the protective film 90 and the deformable plate 85 and the electrolytic solution are not in contact with each other, corrosion of the deformable plate 85 due to contact with the electrolytic solution can be avoided. This eliminates the need to consider the corrosion resistance when selecting the material of the deformable plate 85, and only considers mechanical properties such as elasticity and strength, so that the degree of freedom in selecting the material is greatly increased. Can do.

  (3) When the protective film 90 is attached, the protective film 90 is disposed around the negative electrode terminal 16 and the current interrupting unit 80 and then heated and thermally contracted, so that the protective film 90 has an outer surface shape of the negative electrode terminal 16 and It can be suitably attached while being deformed according to the outer surface shape of the current interrupting portion 80.

The above embodiment may be modified as follows.
O While making the inside of the electric current interruption | blocking part 80 into the sealed space which is not open | released by the case 11, the gas (for example, air) of predetermined pressure may be enclosed in the space. In such a secondary battery, the predetermined pressure is applied to the surface of the deformable plate 85 on the lid 13 side (upper side) as a pressure different from the internal pressure of the case 11.

  As the predetermined pressure, a pressure lower than the atmospheric pressure can be used in addition to the substantially atmospheric pressure. When a pressure lower than the atmospheric pressure is employed, a pressure lower than the atmospheric pressure acts on the surface of the deformation plate 85 on the lid 13 side. According to such a secondary battery, since the internal pressure of the current interrupting unit 80 (specifically, the portion covered with the protective film 90) can be made lower than the external pressure of the same portion, the protective film 90 is caused by the pressure difference. Can be attracted to the current interrupting portion 80 side and can be suitably brought into close contact with the opposing surface. Thereby, the sealing function of the protective film 90 can be improved.

  The protective film 90 may be made of a material that contracts with chemicals. Further, the protective film 90 can be formed of a material that expands and contracts such as synthetic rubber. In addition, the protective film 90 can be made of a material that does not expand and contract. In short, the protective film 90 is in a state in which the inner edge of the opening portion connecting the inner surface and the outer surface thereof is in close contact with the opposing surface of the member covered by the protective film 90, and the negative electrode terminal 16 and the current interrupting portion 80 are The material constituting the protective film 90 can be arbitrarily changed as long as it can be attached in a state of covering at least the mating portion.

○ The protective member 86 can be omitted.
○ The caulking member 88 may be omitted.
A substantially cylindrical shape in which the protective film 90 has a shape that does not cover at least a part of the surface on the electrode assembly 14 side of the current interrupting portion 80 and covers the entire circumference of the mating portion of the negative electrode terminal 16 and the current interrupting portion 80. It may be. Even in such a secondary battery, gas intrusion into the case 11 inside the current interrupting portion 80 can be sealed by closely contacting the inner edge of the opening portion of the protective film 90 on the electrode assembly 14 side with the opposing surface.

  Further, in such a secondary battery, the deformable plate 85 can be omitted. In such a secondary battery, the internal pressure of the case 11 acts on the contact plate 81 via the negative electrode conductive member 60. When the internal pressure of the case 11 becomes high at the time of abnormality, the negative pressure welded portion P surrounded by the fracture groove 84 of the negative electrode conductive member 60 is broken and the contact plate 81 as a deformed plate is moved upward. Deforms so that it becomes convex.

The power storage device of the above embodiment can also be applied to a secondary battery having a current interrupting unit integrated with the positive electrode terminal 15.
The power storage device of the above embodiment can also be applied to power storage devices other than secondary batteries, such as capacitors.

  P ... negative electrode welded part, 10 ... secondary battery, 11 ... case, 14 ... electrode assembly, 16 ... negative electrode terminal, 21 ... positive electrode, 22 ... negative electrode, 23 ... separator, 40 ... positive electrode conductive member, 60 ... negative electrode Conductive member, 80 ... current interrupting part, 81 ... contact plate, 82 ... insulating ring, 84 ... breaking groove, 85 ... deformation plate, 90 ... protective film, 91 ... first opening portion, 92 ... second opening portion.

A power storage device for achieving the above object includes: an electrode assembly; a case that accommodates the electrode assembly; an electrode terminal provided in the case; and a conductive member connected to the electrode assembly. Part. In addition, the conductive portion is provided with a deforming plate on which the internal pressure of the case acts on one surface and a pressure different from the internal pressure acts on the other surface, and the deformation plate deforms as the internal pressure increases. The power storage device has a current interrupting portion having a structure for breaking the battery. Further, the power storage device is a protective film that covers at least the joining portion of the current interrupting portion and the electrode terminal, and the inner edge of the opening portion that connects the inner surface and the outer surface is in close contact with the opposing surface of the inner edge. Has a protective film.

According to the power storage device, by covering the mating portion between the current interrupting portion and the electrode terminal with the protective film, it is possible to seal the gas intrusion into the current interrupting portion from the inside of the case.
In the electric storage device, the protective film is preferably a bag shape that covers the entire matching portion between said electrode terminal the current blocking portion.

Claims (5)

An electrode assembly;
A case for housing the electrode assembly;
A conductive portion for conducting the electrode terminal provided in the case and the conductive member connected to the electrode assembly;
A deforming plate is provided on one surface where the internal pressure of the case acts and a pressure different from the internal pressure acts on the other surface, and the conductive portion is broken by deformation of the deforming plate as the internal pressure increases. A current interrupting part having a structure
A protective film that covers at least the mating part of the current interrupting part and the electrode terminal, and a protective film in which the inner edge of the opening part connecting the inner surface and the outer surface is in close contact with the opposing surface of the inner edge; A power storage device.   2. The power storage device according to claim 1, wherein the protective film has a bag shape that covers the entire mating portion of the current interrupting portion and the electrode terminal.   The power storage device according to claim 1, wherein the protective film is made of a heat-shrinkable material.   The power storage device according to any one of claims 1 to 3, wherein the pressure different from the internal pressure is a pressure lower than an atmospheric pressure enclosed in the current interrupting portion.   The power storage device according to any one of claims 1 to 4, wherein the power storage device is a secondary battery.