JP2016054023A - Power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage device which enables the gas exhaustion from inside a case while avoiding the re-establishment of electrical continuity after the activation of a current interrupt part.SOLUTION: A secondary battery 10 comprises: a case 11; a deformable plate 85 having a shape for sealing the inside of the case from outside; a negative electrode welded part P electrically connecting between a negative electrode terminal 16 provided on the case 11 and a negative electrode conductive member 60 connected to an electrode assembly 14; 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 11. The inside pressure of the case 11 acts on one face of the deformable plate 85, whereas an external pressure of the case 11 acts on the other face. The deformable plate 85 has a breaking part 85b which is broken by deformation in the event of abnormality. The secondary battery 10 has a gas permeable film 90 arranged so that gas can pass therethrough, but an electrolytic solution cannot go therethrough. The gas permeable film 90 is provided to make a partition between the inside of the case 11, and the negative electrode welded part P and the deformable plate 85.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 having a positive electrode and a negative electrode, and a case for housing 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 (for example, Patent Document 1). This current interruption part has a deformation plate as a diaphragm. The deformable plate has a disc shape that is convex on the side away from the inner surface of the case, and the internal pressure of the case acts on one surface and the external pressure acts on the other surface.

  In such a secondary battery, when an abnormality such as overcharging occurs, gas is generated in the case and the internal pressure of the case increases. At this time, the deformable plate is deformed by receiving the pressure and has a convex shape on the inner surface side of the case. Along with this, the conducting part that conducts the electrode terminal provided in the case and the conductive member connected to the electrode assembly is physically broken, and the current of the secondary battery is cut off.

International Publication No. 2013/154166 Pamphlet

  The secondary battery is not preferable because the case is maintained in a state in which the internal pressure of the case remains high after the current interrupting portion is activated in the event of an abnormality. Here, if the structure is such that the gas in the case is discharged out of the case via the current interrupting part after the current interrupting part is activated, the internal pressure of the case can be reduced. However, in this case, there is a possibility that the electrolytic solution may penetrate to the conductive portion in a broken state, and the conductive portion may be re-conducted by electrolytic corrosion via the electrolytic solution.

  This invention was made paying attention to the problem which exists in the said prior art, The objective is the electrical storage which can discharge | emit gas from the inside of a case, avoiding the re-conduction after the action | operation of an electric current interruption part. To provide an apparatus.

  A power storage device for achieving the above object includes an electrode assembly, a case for housing the electrode assembly, the inside of the case being sealed from the outside, and the internal pressure of the case acting on one surface. A deformable plate on which the external pressure of the case acts on the other surface, and a conductive portion that conducts the electrode terminal provided on the case and the conductive member connected to the electrode assembly. A current interrupting portion having a structure in which when the internal pressure rises due to gas generation, the conductive plate is deformed by receiving and deforming the internal pressure plate. The deformable plate has a break portion that breaks when deforming during the abnormality. The power storage device is provided with a gas permeable membrane that allows the gas to permeate but does not allow the electrolyte to permeate between the inside of the case and the conductive portion and the deformation plate.

  According to the above power storage device, the gas generated in the case permeates the gas permeable membrane, so that the case internal pressure that has been increased during an abnormality is applied to the deformation plate, and the deformation plate is deformed by the internal pressure. It becomes like this. Since the deformation plate is broken when the deformation plate is deformed, the inside of the case communicates with the outside through the broken portion. As a result, gas can be discharged from the inside of the case to the outside, and it can be avoided that the internal pressure of the case is kept high after the operation of the current interrupting portion. Moreover, since the electrolyte does not permeate through the gas permeable membrane, it is avoided that the electrolyte enters the portion where the conducting portion is broken at the time of abnormality, and re-conduction of the conducting portion after the operation of the current interrupting portion is avoided. be able to.

  In the above power storage device, the deformation amount of the deformation plate at which the gap between the break portions of the conducting portion at the time of abnormality is the minimum spatial distance is defined as “V1”, and the deformation amount of the deformation plate exceeding the break limit of the deformation plate is Assuming “V2”, it is preferable that the deformation amounts V1 and V2 satisfy the relational expression “V2> V1”.

If the fracture portion of the deformable plate breaks at an excessively early timing, the deformable plate cannot be appropriately deformed, and the conductive portion may not be able to be broken.
In this respect, according to the power storage device, the deformation amount of the deformation plate is a deformation amount that can reliably break the conducting portion, and the deformation amount that ensures the minimum spatial distance (insulation distance) of the broken portion. Until then, the deformation plate does not break. Therefore, the deformation plate can be appropriately deformed to reliably cut off the current of the power storage device. Moreover, after the current is cut off in this way, the fracture portion of the deformable plate can be broken.

The said electrical storage apparatus WHEREIN: The said fracture | rupture part can be made into a weak weak part compared with the other part in the said deformation | transformation board.
According to the power storage device, since a desired position of the deformable plate, that is, a formation position of the fragile portion can be broken, it is possible to appropriately control the breaking mode and the deformed mode when the deformed plate is deformed.

  According to the present invention, gas can be discharged from the inside of the case while avoiding re-conduction after the operation of the current interrupting portion.

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. Sectional drawing which expands and shows a deformation | transformation board periphery. The top view of the deformation | transformation board of other embodiment. Sectional drawing which expands and shows the negative electrode terminal periphery of other embodiment.

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. The electrolyte contains a component that generates hydrogen gas when an abnormality such as overcharge occurs, specifically, when the potential of the positive electrode becomes excessively high. The positive electrode terminal 15 and the negative electrode terminal 16 are on the lid 13 of the case 11 and are arranged 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, and is bonded 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. The positive electrode shaft portion 52 is inserted through an insulating O-ring 53 and an insulating flanged ring 54 that fits into the through hole 13b. 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 fitted with 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. The negative electrode shaft portion 72 is inserted through an insulating O-ring 73 and an insulating flanged ring 74 fitted into the through hole 13b. 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 from the electrode assembly 14 toward the lid 13. The negative electrode terminal 16 has a through hole 16a. The through hole 16a passes through the negative electrode terminal in the axial direction of the negative electrode terminal 16, and 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. 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 made of a conductive material, 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 exists between the outer periphery of the contact plate 81 and the upper surface 60 a of the negative electrode conductive member 60. 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. Further, there is a seal member 83 outside the insulating ring 82 and between the negative electrode head 71 and the negative electrode conductive member 60.

  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 from the lid 13 toward the electrode assembly 14 side (downward) in the normal state, and is directed upward at a position facing the negative electrode welded portion P in the convex portion in the vertical direction. There is a protruding 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 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 disc shape, and a support recess 86 a that is recessed along the deformed plate 85 that protrudes downward exists on the upper surface of the protection member 86. There are a plurality of gas holes 86b penetrating in the vertical direction on the bottom surface of the support recess 86a.

  A gas permeable membrane 90 exists below the protective member 86. The gas permeable membrane 90 is made of a material (for example, a zeolite membrane) that transmits hydrogen gas generated in the case 11 at the time of abnormality and does not transmit electrolyte. The gas permeable membrane 90 has a disc shape that covers the entire lower surface of the protective member 86, and is provided in a manner that partitions the inside of the case 11 from the negative electrode welded portion P and the deformation plate 85.

  In the secondary battery 10, air outside the case 11 enters the current interrupting part 80 through the gap between the lower surface 71 b of the negative electrode head 71 and the contact plate 81 and the through hole 16 a of the negative electrode terminal 16. A pressure (substantially atmospheric pressure) outside the case 11 acts on one surface (the surface on the lid 13 side) of the deformation plate 85. 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 gas permeable film 90.

  As shown in FIGS. 5 to 7, the secondary battery 10 includes an insulating negative electrode insulating member 87 covering the upper surface 71 a and the outer peripheral surface of the negative electrode head 71, a negative electrode head 71, a contact plate 81, an insulating ring 82, and a seal. A caulking member 88 that unitizes the member 83, the negative electrode conductive member 60, the deformation plate 85, and the protection member 86 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 escape 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.

  In the secondary battery 10, since hydrogen gas permeates through the gas permeable membrane 90, when hydrogen gas is generated inside the case 11 at the time of abnormality, the internal pressure of the case 11 that has increased accordingly acts on the deformation plate 85. become. When the internal pressure of the case 11 exceeds the specified pressure, the deformation plate 85 is deformed so as to be convex upward by the internal pressure, as shown by a two-dot chain line in FIGS. 6 and 7. . 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.

  In the secondary battery 10, the deformation amount of the deformable plate 85 in which the gap of the broken portion of the negative electrode welded portion P at the time of abnormality is the minimum spatial distance (state indicated by a solid line in FIG. 8) is “V1”. If the deformation amount of the deformation plate 85 exceeding the limit is “V2”, the material and shape of the deformation plate 85 are set so that the deformation amounts V1 and V2 satisfy the relational expression “V2> V1”.

  In the secondary battery 10, a part of the deformable plate 85 is broken in the process of deforming the deformable plate 85 at the time of abnormality. In the present embodiment, the portion that breaks when the deformable plate 85 is deformed becomes the break portion 85b (FIG. 7). Then, via the broken portion 85b, the electrode assembly 14 side portion from the deformation plate 85 and the lid 13 side portion from the deformation plate 85 communicate with each other, and the inside and the outside of the case 11 communicate with each other. Become.

According to the present embodiment, the following effects can be obtained.
(1) When the deformation plate 85 is deformed, the inside and the outside of the case 11 communicate with each other via the fractured portion 85b where the deformation plate 85 is broken. It can be avoided that the internal pressure of the case 11 is kept high after the operation of the current interrupting unit 80. Moreover, since the electrolyte does not permeate through the gas permeable membrane 90, it is avoided that the electrolyte enters the broken portion of the negative electrode welded portion P at the time of abnormality. Therefore, it is possible to avoid reconduction of the negative electrode welded portion P due to electrolytic corrosion via the electrolytic solution after the operation of the current interrupting portion 80.

  (2) If the deformation plate 85 is broken at an excessively early timing when the deformation plate 85 is deformed, the deformation plate 85 cannot be appropriately deformed, and the negative electrode welded portion P may not be broken. . In this regard, according to the secondary battery 10 of the present embodiment, the deformation amount of the deformation plate 85 is a deformation amount that can surely break the negative electrode welded portion P, and the minimum spatial distance (insulation) of the broken portion. The deformation plate 85 does not break until the deformation amount (distance V1) is secured. Therefore, the deformation plate 85 can be appropriately deformed to reliably cut off the current of the secondary battery 10. Moreover, after the current is cut off in this way, the breaking portion 85b of the deformation plate 85 can be broken at the timing when the deformation amount of the deformation plate 85 becomes the deformation amount V2 larger than the deformation amount V1.

The above embodiment may be modified as follows.
If the breakage of the negative electrode welded portion P due to the deformation of the deformation plate 85 and the breakage of the breakage portion 85b of the deformation plate 85 can both be properly performed, the deformation amounts V1 and V2 can be expressed by the relational expression “V2 ≦ V1”. You may set the material and shape of the deformation | transformation board 85 so that it may satisfy | fill.

  O You may make it provide the weakened part which is weak compared with another part in the deformation | transformation board 85. FIG. As such a weak part, a thinner part than the other part in the deformation | transformation board 85 can be provided. In addition, as shown in FIG. 9, an arc-shaped fracture groove 116 can be provided as a fragile portion on the deformation plate 115. According to such a secondary battery, since the desired position of the deformable plate, that is, the fragile portion can be broken, it is possible to appropriately control the break mode and the deform mode when the deformed plate is deformed.

  As shown in FIG. 10, the blocking recess 60 c of the negative electrode conductive member 60 may be provided with a protruding portion 120 having a shape protruding downward. According to such a secondary battery, the deformation plate 85 can be pierced by the convex portion 120 when the deformation plate 85 is deformed at the time of abnormality. In this secondary battery, the portion of the deformable plate 85 that is pierced by the convex portion 120 becomes the fracture portion 121. In such a secondary battery, the portion of the deformable plate 85 where the convex portion 120 is broken may be made weaker than the other portion.

  (Circle) the secondary battery of the said embodiment is applicable also to the secondary battery which does not have the deformation | transformation board 85. FIG. In such a secondary battery, for example, the outer peripheral portion of the contact plate 81 protruding from the terminal concave portion 71 c and the peripheral portion of the terminal concave portion 71 c on the lower surface 71 b of the negative electrode head portion 71 are fixed by welding. As a result, the contact plate 81 has a shape that seals the inside of the case 11 from the outside, and is a deformed plate in which the internal pressure of the case 11 acts on one surface and the external pressure of the case 11 acts on the other surface. . In such a secondary battery, the internal pressure of the case 11 acts on the lower surface of the contact plate 81 via the negative electrode conductive member 60 and the gas permeable film 90. 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. And in the case of this deformation | transformation, what is necessary is just to make it the structure where the fracture | rupture part of the contact plate 81 fractures | ruptures.

  The secondary battery of the above embodiment can also be applied to a secondary battery having an electrolytic solution containing a component that generates a gas other than hydrogen gas (for example, methane gas, carbon dioxide, carbon monoxide, etc.) in an abnormal state. In such a secondary battery, a gas permeable membrane that is made of a material that transmits gas generated during an abnormality and does not transmit electrolyte can be used.

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, 85, 115 ... deformed plate, 85b, 121 ... broken portion, 90 ... gas permeable membrane, 120 ... broken groove.

Claims (3)

An electrode assembly;
A case for housing the electrode assembly;
A deformation plate that seals the inside of the case from the outside, and the internal pressure of the case acts on one surface and the external pressure of the case acts on the other surface, the electrode terminal provided on the case, A conductive portion that conducts with a conductive member connected to the electrode assembly, and the deformation plate is deformed by receiving the internal pressure when the internal pressure rises due to generation of gas at the time of abnormality. In a power storage device comprising a current interrupting portion having a structure in which the conducting portion breaks,
The deformation plate has a breaking portion that breaks when deforming at the time of the abnormality,
The power storage device is characterized in that a gas permeable membrane that allows the gas to pass therethrough and does not allow electrolyte to pass through is provided in a manner that partitions the interior of the case from the conductive portion and the deformation plate. .   When the amount of deformation of the deformed plate where the gap between the fractured portions of the conducting portion at the time of the abnormality is the minimum spatial distance is “V1” and the amount of deformation of the deformed plate exceeding the break limit of the deformed plate is “V2”. The power storage device according to claim 1, wherein the deformation amounts V1 and V2 satisfy a relational expression “V2> V1”.   The power storage device according to claim 1, wherein the fracture portion is a fragile portion that is weaker than other portions of the deformable plate.