WO2017119421A1 - Electricity storage element - Google Patents

Abstract

The present invention provides an electricity storage element (1) which is provided with: an outer case (4) that contains an electrode body (2); an external terminal (20) that is provided outside the outer case (4); a diaphragm (50) that is arranged in a conduction path between the electrode body (2) and the external terminal (20) and has a displacement part (55) which is displaceable toward the outside of the outer case (4) to a predetermined position by means of an increase of the internal pressure of the outer case (4); and a conductive member (37) that is arranged in a conduction path between the diaphragm (50) and either the electrode body (2) or the external terminal (20), and has a base surface part (38) which is arranged to face the inner side of the diaphragm (50) within the outer case (4), a projection part (40) which protrudes from the base surface part (38) toward the diaphragm (50) in a conical or tubular shape, and an end face part (42) which is provided at the front end of the projection part (40) and is bonded to the displacement part (55) of the diaphragm (50).

Description

Electricity storage element

The present invention relates to a storage element including a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery.

In a storage element including a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery, a gas discharge valve may be provided in an exterior body that houses the electrode body. In this case, when the electrode body generates heat due to overcharge and gas is generated inside the exterior body, the gas can be discharged to the outside of the exterior body through the gas discharge valve.

Further, as disclosed in, for example, Patent Document 1, a power storage device including a current interrupting diaphragm (inversion film) is known. This diaphragm has conductivity, and forms a part of a conductive path between the electrode body and the external terminal together with another conductive member. The diaphragm normally has a displacement portion protruding toward the conductive member, and the diaphragm and the conductive member are electrically connected to each other by being joined to the conductive member at the displacement portion. The conductive member is provided with a cutting portion made of a cut such as a half cut. The cutting part is formed in an endless shape such as a circle. A portion surrounded by the cutting portion is a detachable portion that can be separated from the conductive member, and is joined to the displacement portion of the diaphragm at the detachable portion.

In this type of power storage element, when the pressure in the exterior body rises to a predetermined pressure due to the generation of gas, the diaphragm is inverted so that the displacement portion is separated from the conductive member. At this time, the cut-off portion of the conductive member joined to the displacement portion of the diaphragm is cut off from the conductive member along the cut portion, and is displaced in a direction away from the conductive member together with the displacement portion of the diaphragm. When the diaphragm is separated from the conductive member in this manner and the electrical connection between the conductive member and the diaphragm is interrupted, overcharging is stopped and further heat generation of the electrode body is suppressed. Such inversion of the diaphragm is performed before the gas discharge valve is opened, so that it is possible to suppress excessive heat generation of the electrode body in which gas must be discharged through the gas discharge valve.

JP 2013-214474 A

However, when the current is interrupted by the inversion of the diaphragm as described above, when the separation part of the conductive member is displaced together with the displacement part of the diaphragm and is to be separated from the conductive member, the periphery of the separation part of the conductive member The portion may be deformed so as to protrude toward the diaphragm side by being pulled by the separation portion. When the projecting portion generated in the conductive member due to this deformation comes into contact with the diaphragm, unintentional energization may occur between the diaphragm and the conductive member, so there is room for improvement in current interruption performance.

Therefore, an object of the present invention is to provide a power storage device capable of improving current interruption performance.

The present invention
An exterior body that houses the electrode body;
An external terminal provided outside the exterior body;
A displacement portion that can be displaced to a predetermined position toward the outside of the exterior body by an increase in internal pressure of the exterior body, and a diaphragm provided in a conductive path between the electrode body and the external terminal;
A base surface portion disposed oppositely to the inside of the diaphragm in the exterior body, a projecting portion projecting in a conical or cylindrical shape from the base surface portion toward the diaphragm, and a tip of the projecting portion. Provided is an energy storage device that includes an end surface portion joined to the displacement portion and includes a conductive member provided in a conductive path between either the electrode body or the external terminal and the diaphragm. .

In addition, the “conical shape” and the “cylindrical shape” in the present specification are not limited to the conical shape and the cylindrical shape, and may be a pyramid shape and a rectangular tube shape, for example. That is, the cross-sectional shape of the “conical” or “cylindrical” protruding portion is not limited to a circular shape, and the protruding portion may have various cross-sectional shapes including a polygon.

According to this power storage element, when the displacement portion of the diaphragm is displaced away from the base surface portion of the conductive member due to the increase in the internal pressure of the exterior body, the conductive member portion joined to the displacement portion of the diaphragm is electrically conductive together with the displacement portion. The member is displaced away from the base surface portion and the protruding portion of the member, and is separated from the conductive member. Since the protruding portion of the conductive member originally protrudes from the base surface portion toward the diaphragm, even if the protruding portion is pulled to the diaphragm side by a portion that is displaced together with the displacement portion of the diaphragm and is separated from the conductive member, the protruding portion is moved to the diaphragm side. Further, it is difficult for deformation of the protruding portion to protrude. Therefore, the contact between the diaphragm after reversal and the conductive member can be reliably prevented, so that the energization between the electrode body and the external terminal can be reliably interrupted. Therefore, it becomes easy to suppress the heat_generation | fever of a further electrode body and generation | occurrence | production of gas, and it becomes easy to avoid discharge | release of the gas through a gas discharge valve by this.

According to the electricity storage device according to the present invention, after the energization between the diaphragm and the conductive member is interrupted by the inversion of the diaphragm, the contact between the diaphragm and the conductive member can be reliably prevented, thereby The current interruption performance can be improved.

The perspective view of the battery which concerns on 1st Embodiment of this invention. The longitudinal cross-sectional view of the battery of FIG. FIG. 2 is an exploded perspective view of a part of the battery of FIG. 1. FIG. 2 is a partially broken perspective view of a main part of the battery of FIG. 1. The partially broken perspective view which looked at the battery part of FIG. 4 from another direction. Sectional drawing which shows a diaphragm and its peripheral part. Sectional drawing similar to FIG. 6 which shows the state which the diaphragm reversed. The figure which shows typically the principal part of a diaphragm and a collector. Sectional drawing which shows an example of the welding operation | work of a diaphragm and a collector. The schematic diagram similar to FIG. 8 which shows the modification of a diaphragm. The partially broken perspective view similar to FIG. 4 which shows the modification of the battery which concerns on 1st Embodiment. Sectional drawing which shows an example of the welding operation | work of a diaphragm and a collector with the battery of FIG. The perspective view of the battery which concerns on 2nd Embodiment of this invention. FIG. 14 is a longitudinal sectional view of the battery of FIG. 13. The exploded perspective view of the battery of FIG. The partially broken perspective view of the principal part of the battery of FIG. The partially broken perspective view which looked at the battery part of FIG. 16 from another direction. Sectional drawing which shows the diaphragm of the battery of FIG. 13, and its peripheral part. The figure which shows typically the principal part of a diaphragm and a collector.

Hereinafter, embodiments according to the present invention will be described with reference to the accompanying drawings. In the following description, terms indicating specific directions and positions (for example, terms including “up”, “down”, “side”, “end”) are used as necessary. Is for facilitating understanding of the invention with reference to the drawings, and the technical scope of the present invention is not limited by the meaning of these terms. Further, the following description is merely illustrative in nature and is not intended to limit the present invention, its application, or its use.

[First Embodiment]
1 and 2 show a lithium ion secondary battery (hereinafter simply referred to as “battery”) 1 as a power storage device according to a first embodiment of the present invention.

[overall structure]
1 and 2, the battery 1 includes an electrode body 2, an exterior body 4, positive and negative external terminals 10 and 20, positive and negative current collectors 17 and 37, upper gaskets 14 and 28, and a lower gasket 16. , 32, a current interrupting diaphragm (inversion film) 50 and a discharging terminal 24.

The exterior body 4 includes a case main body 5 whose upper end is opened and a lid 6 that closes the upper end opening of the case main body 5. In the present embodiment, the case body 5 and the lid 6 are made of aluminum or an aluminum alloy. The case body 5 has a rectangular plate-like bottom wall portion 5b, a pair of long side wall portions 5c and 5d rising from the long side of the bottom wall portion 5b, and a pair of short side wall portions 5e and 5f rising from the short side of the bottom wall portion 5b. With. The lid 6 has a generally rectangular plate shape. The lid 6 is provided with a gas discharge valve 8 for discharging the gas generated in the case body 5 to the outside of the exterior body 4.

As shown in FIG. 2, the electrode body 2 is accommodated in a case body 5 filled with an electrolytic solution. The electrode body 2 may be covered with an insulating sheet (not shown). In the case body 5, lower gaskets 16 and 32 and current collectors 17 and 37 are also accommodated.

The electrode body 2 is formed by laminating two separators made of a positive and negative electrode sheet and a microporous resin sheet, each of which is a long strip having a constant width, and is wound into an elliptical shape having a generally high flatness. It is. The axis of winding (winding axis) of the electrode sheet and the separator of the electrode body 2 is conceptually indicated by the symbol X in FIG. The electrode body 2 is accommodated in the case body 5 in such a manner that the winding axis X extends in a direction in which the pair of short side wall portions 5e and 5f of the case body 5 face each other (in the left-right direction in FIG. 2).

At one end (right side in FIG. 2) of the electrode body 2 in the direction in which the winding axis X extends, the negative electrode sheet protrudes from the positive electrode sheet and the separator, and the other (left side in FIG. 2). At the end, the positive electrode sheet protrudes beyond the negative electrode sheet and the separator. The protruding portions of these electrode sheets are uncoated portions where no active material layer is provided on any surface of the metal foil. Thereby, the negative electrode lead part 2a formed by laminating only the metal foil of the negative electrode sheet is formed at one end (right side in FIG. 2) of the electrode body 2 in the extending direction of the winding axis X, and the other A positive electrode lead portion 2b formed by laminating only the metal foil of the positive electrode sheet is formed at the end portion (left side in FIG. 2).

Referring to FIG. 3 in addition to FIGS. 1 and 2, a negative external terminal 10 is disposed on one end side (right side in FIGS. 1 and 2) of the lid 6 and the other end side (left side in FIGS. 1 and 2). The positive external terminal 20 and the discharge terminal 24 are arranged on the top. The external terminals 10, 20 and the discharge terminal 24 include plate- like portions 11, 22, 25 arranged on the outer side surface (upper side surface) of the lid 6. A connecting member such as a bus bar is welded to the plate- like portions 11, 22 and 25 and connected to an external circuit.

The negative external terminal 10 includes a plate-like portion 11 disposed on the outer surface of the lid 6 and a columnar shaft portion 12 protruding downward from the lower surface of the plate-like portion 11. The shaft portion 12 is composed of a rivet separate from the plate-like portion 11. In this embodiment, the negative electrode external terminal 10 is made of copper or a copper alloy with a plate-like portion 11 made of aluminum or an aluminum alloy and a shaft portion 12 plated.

The shaft portion 12 penetrates the upper gasket 14 made of insulating resin and the lid 6 and protrudes into the case body 5. The lower gasket 16 made of insulating resin and the negative electrode current collector 17 are formed inside the case body 5. It further penetrates (base surface portion 18 described later). The upper gasket 14 is provided with a cylindrical portion 14 a (see FIG. 3) through which the shaft portion 12 is inserted, and the shaft portion 12 is provided on the lid 6, the lower gasket 16, and the base surface portion 18 of the current collector 17. Through holes 6a, 16a, 18a (see FIG. 3) for insertion are provided. A cylindrical portion 14 a of the upper gasket 14 is interposed between the inner peripheral surface of the through hole 6 a of the lid 6 and the outer peripheral surface of the shaft portion 12.

A diameter-enlarged portion 12a (see FIG. 2) is formed at the lower end of the shaft portion 12 of the negative external terminal 10 by caulking, whereby the negative external terminal 10 is caulked and fixed to the lid 6. Specifically, the upper gasket 14, the lid 6, the lower gasket 16, and the base surface portion 18 of the negative electrode current collector 17 are sandwiched between the plate-like portion 11 and the enlarged diameter portion 12 a of the external terminal 10. The negative external terminal 10 and the current collector 17 are fixed to the lid 6. An upper gasket 14 is interposed between the outer side surface (upper side surface) of the lid 6 and the external terminal 10, and a lower gasket 16 is interposed between the inner side surface (lower side surface) of the lid 6 and the current collector 17. It is disguised.

The positive external terminal 20 is formed of a hollow bulge that bulges outward (upper) from the lid 6. The external terminal 20 is provided integrally with the lid 6. That is, in the present embodiment, the positive external terminal 20 is made of aluminum or an aluminum alloy, like the lid 6. There is no need to provide an insulating member between the lid 6 and the external terminal 20 having the same potential. If an insulating member is provided between the lid 6 and the external terminal 20, it is necessary to attach the insulating member to the lid 6 and the external terminal 20 in order to ensure airtightness. Since the lid 6 and the external terminal 20 are integrated, airtightness can be easily ensured.

The external terminal 20 includes a cylindrical peripheral wall portion 21 that protrudes upward from the lid 6, and a plate-like portion 22 that closes the upper end opening of the peripheral wall portion 21. The peripheral wall portion 21 is, for example, cylindrical with an opening at the lower end, and the plate-like portion 22 is, for example, a circle having the same diameter as the outer diameter of the peripheral wall portion 21. An opening 22a for avoiding interference with a support pin 201 (see FIG. 9) of a welding work jig to be described later is provided at the center of the plate-like portion 22.

The discharge terminal 24 is connected to the positive electrode external terminal 20 and the electrode body 2 by reversal of a current interrupting diaphragm 50, which will be described later, in an emergency when the internal pressure of the exterior body 4 rises to a predetermined pressure or more due to overcharging, for example. It is provided to discharge when interrupted.

The discharge terminal 24 is disposed outside the positive external terminal 20 in the length direction of the lid 6. The discharge terminal 24 includes a plate-like portion 25 disposed on the outer surface of the lid 6 and a columnar shaft portion 26 that protrudes downward from the lower surface of the plate-like portion 25. The shaft portion 26 is formed integrally with the plate-like portion 25. In the present embodiment, the discharge terminal 24 is made of aluminum or an aluminum alloy.

The shaft portion 26 penetrates the upper gasket 28 made of insulating resin and the lid 6 and protrudes into the case body 5, and the lower gasket 32 made of insulating resin and the positive electrode current collector 37 inside the case body 5. It further penetrates (a base surface portion 38 described later). The upper gasket 28 is provided with a cylindrical portion 28 a (see FIG. 3) through which the shaft portion 26 is inserted, and the shaft portion 26 is provided on the lid 6, the lower gasket 32, and the base surface portion 38 of the current collector 37. Through holes 6b, 33b, and 38a (see FIG. 3) for insertion are provided. A cylindrical portion 28 a of the upper gasket 28 is interposed between the inner peripheral surface of the through hole 6 b of the lid 6 and the outer peripheral surface of the shaft portion 26.

An enlarged-diameter portion 26a (see FIGS. 2, 4 and 5) is formed at the lower end of the shaft portion 26 of the discharge terminal 24 by caulking. As a result, the discharge terminal 24 is fastened and fixed to the lid 6. Specifically, the upper gasket 28, the lid 6, the lower gasket 32, and the base surface portion 38 of the positive electrode current collector 37 are sandwiched between the plate-like portion 25 and the enlarged diameter portion 26a of the discharge terminal 24. The discharge terminal 24 and the current collector 37 are fixed to the lid 6. An upper gasket 28 is interposed between the outer surface of the lid 6 and the discharge terminal 24, and a lower gasket 32 is interposed between the inner surface of the lid 6 and the positive electrode current collector 37.

The negative electrode current collector 17 includes a base surface portion 18 fixed to the lid 6 and a pair of leg portions 19 a and 19 b extending downward from the base surface portion 18. The negative electrode current collector 17 is made of copper or a copper alloy. The base surface portion 18 is caulked and fixed to the lid 6 by the enlarged diameter portion 12a formed in the shaft portion 12 of the negative external terminal 10 as described above. The pair of leg portions 19 a and 19 b are arranged so as to sandwich the negative electrode lead portion 2 a of the electrode body 2. Each leg part 19a, 19b is welded to the negative electrode lead part 2a, and is electrically and mechanically connected. Thus, the negative electrode lead portion 2 a of the electrode body 2 is electrically connected to the negative electrode external terminal 10 via the negative electrode current collector 17.

Similarly, the positive electrode current collector 37 includes a base surface portion 38 fixed to the lid 6 and a pair of leg portions 39a and 39b extending downward from the base surface portion 38. The positive electrode current collector 37 is made of aluminum or an aluminum alloy. As described above, the base surface portion 38 is caulked and fixed to the lid 6 by the enlarged diameter portion 26 a formed in the shaft portion 26 of the discharge terminal 24. The pair of leg portions 39 a and 39 b are arranged so as to sandwich the positive electrode lead portion 2 b of the electrode body 2. Each leg part 39a, 39b is welded to the positive electrode lead part 2b, and is electrically and mechanically connected.

The positive current collector 37 is a conductive member provided in a conductive path between a current-blocking diaphragm 50 and an electrode body 2 described later, and is electrically connected to the positive external terminal 20 via the diaphragm 50. Has been.

Thus, the positive external terminal 20 is electrically connected to the positive electrode lead portion 2 b of the electrode body 2 through the diaphragm 50 and the current collector 37. The positive external terminal 20 is integrated with the lid 6 as described above, so that it has the same potential as the exterior body 4.

The case body 5 having the same potential as that of the positive external terminal 20 is prevented from being energized with the negative current collector 17 or directly with the positive current collector 37. Therefore, it is preferable to interpose a spacer (not shown) made of an insulating material between the positive and negative current collectors 17 and 37 and the case body 5.

Hereinafter, the configuration of the diaphragm 50 and the more specific configuration of the positive electrode current collector 37 and the lower gasket 32 related thereto will be described.

[Diaphragm for current interruption and related structure]
As shown in FIGS. 4 to 6, the diaphragm 50 is disposed to face the lower side of the positive external terminal 20 and is joined to the lid 6 and the lower end of the external terminal 20 at the outer peripheral portion. The diaphragm 50 partitions the first space S1 inside the case body 5 from the second space S2 inside the positive external terminal 20 that bulges outward (upward) from the lid 6.

The diaphragm 50 is a conductive member provided in a conductive path between the positive electrode lead portion 2b of the electrode body 2 and the external terminal 20 of the positive electrode. The diaphragm 50 is electrically connected directly to the external terminal 20, and is electrically connected to the positive electrode lead portion 2 b of the electrode body 2 via the current collector 37. The diaphragm 50 is made of, for example, aluminum or an aluminum alloy.

The diaphragm 50 includes an outer annular portion 51 that forms an outer periphery thereof, a cylindrical portion 52 that extends in the axial direction from the radially inner end of the outer annular portion 51 toward the plate-like portion 22 of the external terminal 20, and a cylindrical portion 52 expands radially outward from the outer edge of the displacement portion 55, the diameter expansion portion 53 connected to the tip of 52, the displacement portion 55 that can be displaced to a predetermined position in the direction away from the first space S1 by the increase in internal pressure of the first space S1. And a flare portion 54 connected to the enlarged diameter portion 53. The contours of the outer annular portion 51, the cylindrical portion 52, the enlarged diameter portion 53, the flare portion 54, and the displacement portion 55 are, for example, circular, but the shapes of these contours are not particularly limited.

An annular notch 6 c for joining the diaphragm 50 to the lid 6 is provided at a corner portion between the lower end portion of the peripheral wall portion 21 of the external terminal 20 and the lid 6. The notch 6c is formed in a step shape that opens toward the first space S1 and the second space S2. The outer periphery of the outer annular portion 51 of the diaphragm 50 is fitted into the notch 6c. The inner side surface (lower side surface) of the outer annular portion 51 is disposed on the same plane as the inner side surface of the lid 6. The outer annular portion 51 is joined to the lid 6 by laser welding, for example. Laser welding is performed over the entire circumference along the outer edge of the outer annular portion 51 by, for example, laser irradiation from below. Thus, the diaphragm 50 is held by the exterior body 4 by mechanical connection with the lid 6, and is electrically connected directly to the positive external terminal 20 that is integral with the lid 6.

Thereby, a dedicated member for connecting the diaphragm 50 to the external terminal 20 can be omitted. In addition, since there is no need to electrically insulate the diaphragm 50 from the lid 6 that holds the diaphragm 50, an insulating member may not be interposed between the diaphragm 50 and the lid 6. Therefore, the number of parts and assembly man-hours can be reduced.

The cylindrical portion 52 of the diaphragm 50 protrudes from the outer annular portion 51 in a direction away from the first space S1. The distal end (upper end) of the cylindrical portion 52 is disposed on the inner side (lower side) than the outer side surface (upper side surface) of the lid 6.

As shown in FIG. 6, the diameter-enlarged portion 53 of the diaphragm 50 includes a first annular portion 53a extending radially outward from the tip (upper end) of the tubular portion 52, and a plate-like portion 22 from the outer edge of the first annular portion 53a. And a second annular portion 53c extending radially inward from the tip (upper end) of the connecting portion 53b. The outer diameters of the first annular portion 53 a, the connecting portion 53 b, and the second annular portion 53 c are larger than the outer diameter of the cylindrical portion 52 and smaller than the inner diameter of the peripheral wall portion 21 of the external terminal 20. The second annular portion 53c is disposed so as to protrude radially inward from the inner edge of the first annular portion 53a.

In a normal time when the internal pressure of the first space S1 is less than a predetermined pressure, the displacement portion 55 is disposed closer to the first space S1 (lower side) than the enlarged diameter portion 53, and the inner side surface (lower side) of the displacement portion 55 The side surface is, for example, arranged on the same plane as the inner side surface (lower side surface) of the outer annular portion 51. The flare portion 54 connects the outer edge of the displacement portion 55 and the inner edge of the second annular portion 53 c of the enlarged diameter portion 53. The flare part 54 is inclined and arranged in a direction away from the first space S1 toward the radially outer side.

As described above, the diaphragm 50 is provided on the lid 6, and the outer annular portion 51, the tubular portion 52, the enlarged diameter portion 53, the flare portion 54, and the displacement portion 55 of the diaphragm 50 are all the thickness of the lid 6. It is arranged between the inner side surface (lower side surface) and the outer side surface (upper side surface) of the lid 6 in the direction. That is, the diaphragm 50 is provided so as to overlap the lid 6 in the thickness direction. Thus, the entire diaphragm 50 is disposed on the outer side (upper side) than the inner side surface (lower side surface) of the lid 6. Therefore, compared with the case where the diaphragm 50 is arranged in the first space S1 inside the lid 6, a larger layout space of the electrode body 2 in the first space S1 can be secured, and the capacity of the battery 1 can be increased. Can be planned.

In the present embodiment, the entire diaphragm 50 is disposed outside the inner side surface of the lid 6, but a part of the diaphragm 50 may be disposed outside the inner side surface of the lid 6.

Subsequently, a more specific configuration related to the diaphragm 50 with respect to the positive electrode current collector 37 and the lower gasket 32 will be described with reference to FIGS.

The lower gasket 32 has a base surface portion 33 sandwiched between the lid 6 and the base surface portion 38 of the current collector 37. The shape of the base surface portion 33 is a rectangle that is long in the length direction of the lid 6. The base surface portion 33 is provided with an opening 33 a at a position corresponding to the diaphragm 50. The opening 33a has, for example, the same diameter as the inner diameter of the outer annular portion 51 of the diaphragm 50, and the inner peripheral surface of the opening 33a is disposed on the same plane as the inner peripheral surface of the outer annular portion 51 ( (See FIG. 6).

The lower gasket 32 includes a pair of long side surface portions 34a and 34b protruding downward from the long side of the base surface portion 33, and a short side surface portion protruding downward from the short side opposite to the short side wall portion 5e of the case body 5. 35. The lower end of the short side surface portion 35 is disposed above the lower ends of the long side surface portions 34a and 34b.

The shape of the base surface portion 38 of the current collector 37 is a rectangle that is long in the length direction of the lid 6. The base surface portion 38 of the current collector 37 is disposed so as to overlap the inside (lower side) of the base surface portion 33 of the lower gasket 32 in the first space S1. The base surface portion 38 is disposed to face the inner side (lower side) of the diaphragm 50 through the opening 33 a of the lower gasket 32.

The current collector 37 further includes a pair of long side surface portions 44 a and 44 b that protrude downward from the long side of the base surface portion 38. In the short side direction of the base surface portion 38, the long side surface portions 44a and 44b are disposed opposite to the inside of the long side surface portions 34a and 34b of the lower gasket 32, whereby the current collector 37 is placed in the short side direction. Positioning is possible. In addition, the end surface on one short side of the base surface portion 38 is disposed opposite to the short side surface portion 35 of the lower gasket 32, whereby the current collector 37 can be positioned in the long side direction of the base surface portion 38. ing.

At the position corresponding to the diaphragm 50 in the base surface portion 38, a protruding portion 40 protruding toward the diaphragm 50 and an end surface portion 42 provided at the tip of the protruding portion 40 are provided. The protruding portion 40 protrudes from the base surface portion 38 in a conical shape. The end surface portion 42 has a circular shape and is disposed in parallel to the base surface portion 38. Thereby, the truncated cone which makes the protrusion part 40 a side surface and makes the end surface part 42 an upper surface is formed. The protrusion 40 is disposed in the opening 33 a of the lower gasket 32, thereby avoiding interference between the protrusion 40 and the lower gasket 32. An opening 43 is provided at the center of the end surface portion 42.

As shown in FIG. 6, the end surface portion 42 is provided with an endless cutting portion 45, and a portion surrounded by the cutting portion 45 is a separation portion 46 that can be separated from the current collector 37. Yes. The cutting part 45 is formed in a circular shape, for example. A cut is formed in the cut portion 45, whereby the cut portion 45 is easier to break than the portion other than the cut portion 45 in the end face portion 42. The cutting part 45 is formed into a thin part by forming a half-cut cut continuous over the entire circumference. The cut of the cut portion 45 is preferably formed on the inner side surface (lower surface) of the end surface portion 42. In addition, the cut of the cutting part 45 may be a full cut that penetrates the end face part 42 in the thickness direction. In this case, the full cut is provided in a perforated pattern intermittently in the circumferential direction.

The outer surface (upper surface) of the end surface portion 42 is disposed on the same surface as the outer surface (upper surface) of the base surface portion 33 of the lower gasket 32. The end surface portion 42 is joined to the displacement portion 55 of the diaphragm 50 at the separation portion 46. The separation portion 46 is an annular portion outside the opening portion 43 and inside the cutting portion 45 in the end surface portion 42. The separation part 46 is joined to the outer peripheral part of the displacement part 55 by welding performed along the periphery of the opening part 43, for example.

The portion of the displacement portion 55 that is radially inward of the joint portion with the separation portion 46 faces the first space S <b> 1 through the opening 43 of the end surface portion 42. Thereby, the displacement part 55 always receives the internal pressure of the first space S1 directly. However, in the normal time when the internal pressure of the first space S1 is less than the predetermined pressure, the displacement part 55 is separated from the collector 37. 46 is held at the position shown in FIG.

When the internal pressure of the first space S1 rises above a predetermined pressure due to the heat generated by the electrode body 2 due to overcharging and the generation of gas, the diaphragm 50 is deformed so as to be reversed as shown in FIG. The displacement part 55 which received the internal pressure of S1 is displaced to a predetermined position toward the outside of the exterior body 4. At this time, the displacement portion 55 and the separation portion 46 of the current collector 37 joined to the displacement portion 55 are separated from the base surface portion 38 of the current collector 37 toward the outside of the exterior body 4 (external terminal 20). The separating portion 46 is separated from the remaining portion of the current collector 37 along the cutting portion 45.

At this time, the displacement part 55 is displaced from the position protruding from the first annular part 53a to the first space S1 side to the position protruding from the first annular part 53a and the cylindrical part 52 to the anti-first space S1 side. To do. Further, when the diaphragm 50 is inverted in this way, the diameter-enlarged portion 53 of the diaphragm 50 has a shape in which the second annular portion 53c is arranged in parallel to the first annular portion 53a, and the second annular portion 53c is included therein. The edge is deformed into an inclined shape so as to protrude in a direction away from the first space S1. Further, at this time, the flare portion 54 of the diaphragm 50 has a reduced inclination angle toward the first space S1 from the outer edge to the inner edge.

Since the protruding portion 40 of the current collector 37 protrudes toward the diaphragm 50 (on the side opposite to the first space S1) with respect to the base surface portion 38 from the beginning, the separating portion 46 is separated from the current collector 37 as described above. Therefore, even when the protrusion 40 is pulled toward the diaphragm 50 by the separating portion 46 when attempting to be displaced toward the first space S1, the deformation of the protrusion 40 that further protrudes toward the diaphragm 50 is unlikely to occur. Therefore, the current collector 37 can be maintained in a state of being located below the diaphragm 50 (on the side opposite to the plate-like portion 22), and it is ensured that the current collector 37 is in contact with the inverted diaphragm 50 as described above. Can be prevented. Thereby, after the diaphragm 50 is reversed, the energization between the diaphragm 50 and the current collector 37, and thus the energization between the external terminal 20 of the positive electrode and the positive electrode lead portion 2b of the electrode body 2 can be reliably cut off. The current interruption performance of the battery 1 is improved. Therefore, further charging of the battery 1 is avoided, so that it is easy to suppress further heat generation and gas generation of the electrode body 2, thereby easily avoiding gas release through the gas discharge valve 8.

As described above, the second space S2 formed inside the external terminal 20 bulging outward (upward) from the lid 6 functions as a housing space for housing the displacement portion 55 of the diaphragm 50 inverted as described above. To do. In this way, by using the second space S2 formed inside the external terminal 20, the displacement portion 55 of the deformed diaphragm 50 is accommodated, so that a space for accommodating the deformed diaphragm 50 is provided. There is no need to secure the first space S1 in the case body 5. Therefore, a large layout space for the electrode body 2 in the first space S1 can be ensured, and thereby the capacity of the battery 1 can be increased.

As shown in FIG. 6, since the diaphragm 50 is not inverted, a current can be passed between the diaphragm 50 and the current collector 37, and a large current is generated from the diaphragm 50 to the current collector 37 due to an external short circuit or the like. When flowing, the end face portion 42 of the current collector 37 is melted by the cutting portion 45. Also in this case, since the diaphragm 50 and the current collector 37 are not in contact with each other, the conductive path between the positive external terminal 20 and the positive electrode lead portion 2b of the electrode body 2 is cut off. Is protected.

The dimensions of each part of the diaphragm 50 and the current collector 37 will be described with reference to the schematic diagram of FIG. In addition, the dashed-two dotted line in FIG. 8 has shown the diaphragm 50 of the inverted state.

The thickness L2 of the protruding portion 40 of the current collector 37 is preferably larger than the thickness L1 of the end face portion. Thereby, the relatively thin end surface portion 42 is easily broken and melted at the cutting portion 45, and the rigidity of the relatively thick protruding portion 40 is ensured. Since the protrusion 40 has a relatively high rigidity, when the separation part 46 of the end face part 42 is pulled by the diaphragm 50 due to the reversal of the diaphragm 50, the deformation of the protrusion 40 is easily suppressed. At this time, the inner peripheral portion of the end surface portion 42 fixed to the diaphragm 50 is displaced to the anti-first space S1 side, whereas the displacement of the outer peripheral portion of the end surface portion 42 connected to the tip of the protruding portion 40 is suppressed. Therefore, stress tends to concentrate on the cut portion 45 of the end surface portion 42, and the end surface portion 42 is easily broken at the cut portion 45.

The thickness L3 of the base surface portion 38 of the current collector 37 is preferably equal to or greater than the thickness L2 of the protruding portion 40. Thereby, the rigidity of the base surface part 38 is ensured satisfactorily. Therefore, when the protruding portion 40 is pulled toward the diaphragm 50 by the separating portion 46 that is separated from the current collector 37 when the diaphragm 50 is reversed, the deformation of the base surface portion 38 such that the protruding portion 40 approaches the diaphragm 50 is suppressed. Thus, contact between the inverted diaphragm 50 and the protrusion 40 can be reliably prevented, and the current interruption performance of the battery 1 can be satisfactorily exhibited.

The protruding amount L4 of the protruding portion 40 from the base surface portion 38 in the current collector 37 is preferably 1 mm or more and 5 mm or less. Since the protruding portion 40 originally has a protruding amount L4 of 1 mm or more, when the protruding portion 40 is pulled by the separating portion 46 when the diaphragm 50 is reversed, the protruding amount L4 of the protruding portion 40 further increases. The deformation of the electric body 37 can be effectively suppressed. Further, since the protruding amount L4 of the protruding portion 40 is 5 mm or less, the occupied space of the current collector 37 in the first space S1 can be effectively reduced in the vertical direction, thereby increasing the capacity of the battery 1. Can be planned.

The radial dimension L5 from the corner part of the inner peripheral surface of the projecting part 40 of the current collector 37 and the end face part 42 to the cutting part 45 is from the normal position of the displacement part 55 of the diaphragm 50 to the position after inversion. It is preferably smaller than the displacement amount L6. Thereby, when the separation part 46 is separated from the current collector 37 and is displaced together with the displacement part 55 of the diaphragm 50, the outer peripheral part 47 left outside the cutting part 45 in the end face part 42 is the displacement part 55 of the diaphragm 50. By being pulled to the side, even when the outer peripheral portion 47 is deformed so as to protrude toward the diaphragm 50, the outer peripheral portion 47 can be prevented from coming into contact with the diaphragm 50.

An example of a welding operation between the diaphragm 50 and the current collector 37 will be described with reference to a cross-sectional view of FIG.

In the example shown in FIG. 9, the diaphragm 50 and the current collector 37 are welded by joining the diaphragm 50 to the lid 6, and the lower gasket 32 and the current collector 37 are connected to the discharge terminal 24 and the upper gasket 28 (FIG. 4). And FIG. 5). The welding operation is performed in a posture in which the diaphragm 50 is disposed below the current collector 37. As a jig for welding work, a first jig 200 having a support pin 201 for supporting the displacement portion 55 of the diaphragm 50 from below and a second jig for pressing the base surface portion 38 of the current collector 37 from above. A jig 202 is used. The first jig 200 has a flat upper surface, and the support pins 201 protrude upward from the upper surface of the first jig 200.

When performing the welding operation, first, the plate-like portion 22 of the external terminal 20 integrated with the lid 6 is placed on the upper surface of the first jig 200. At this time, the support pin 201 is inserted into the opening 22 a provided in the plate-like portion 22, thereby avoiding interference with the external terminal 20, and the displacement portion 55 of the diaphragm 50 by the upper end of the support pin 201. Can be supported from below.

Subsequently, the end surface portion 42 is brought into close contact with the end surface portion 42 of the current collector 37 and the displacement portion 55 of the diaphragm 50 by pressing the base surface portion 38 of the current collector 37 from above with the second jig 202. A laser is irradiated from the upper side along the periphery of the opening 43 to weld the separation portion 46 of the end face portion 42 to the displacement portion 55 of the diaphragm 50.

The end surface portion 42 of the current collector 37 pressed against the support pin 201 via the displacement portion 55 of the diaphragm 50 at the time of welding is provided at the tip of the protruding portion 40, and the entire outer periphery is supported by the protruding portion 40. Therefore, the stress from the support pin 201 can be received by the protrusion 40. Since the protruding portion 40 has a large thickness in the axial direction of the support pin 201, deformation due to stress from the support pin 201 hardly occurs. Therefore, the current collector due to the stress from the support pin 201 is compared with a case where a portion of the current collector 37 located on the same surface as the base surface portion 38 is pressed against the support pin 201 via the displacement portion 55 of the diaphragm 50. The deformation of the body 37 can be suppressed.

[Diaphragm modifications]
FIG. 10 is a schematic view similar to FIG. 8 showing a diaphragm 150 according to a modification. In the modification shown in FIG. 10, the description of the same components as those in the above example is omitted, and the same reference numerals are given in FIG.

The displacement portion 55 of the diaphragm 150 shown in FIG. 10 includes an annular first surface portion 153 extending radially inward from the inner edge of the flare portion 54 and a cylindrical fitting protruding from the inner edge of the first surface portion 153 toward the first space S1. It has the joint part 154 and the 2nd surface part 155 which block | closes the front-end | tip opening of the fitting part 154. FIG. The first surface portion 153 is overlapped and joined to the end surface portion 42 of the current collector 37 from the side opposite to the first space S1. The fitting portion 154 is fitted into the opening 43 of the end surface portion 42 of the current collector 37. The second surface portion 155 faces the first space S <b> 1 by being disposed on the inner side (lower side) of the end surface portion 42 of the current collector 37.

In the diaphragm 150 shown in FIG. 10, the fitting portion 154 of the displacement portion 55 is formed in the opening portion 43 provided in the end surface portion 42 of the current collector 37 so that the displacement portion 55 of the diaphragm 150 faces the first space S1. When the welding operation as shown in FIG. 9 is performed, the diaphragm 150 can be easily positioned with respect to the current collector 37, and the displacement portion is formed on the inner peripheral surface of the opening 43 of the end surface portion 42. Since the outer peripheral surfaces of the 55 fitting portions 154 face each other, the welding area between the end surface portion 42 and the displacement portion 55 can be increased. Therefore, the diaphragm 150 can be easily welded to the end face portion 42 of the current collector 37 and the joint strength can be improved.

[Modification of battery]
11 is a partially broken perspective view similar to FIG. 4 showing a modification of the battery 1 according to the first embodiment, and FIG. 12 is a weld of the diaphragm 250 and the current collector 37 according to the modification of FIG. It is sectional drawing similar to FIG. 9 which shows an example of an operation | work. In the modification shown in FIGS. 11 and 12, the description of the same components as those in the above example is omitted, and the same reference numerals are given in FIGS.

In the modification shown in FIG. 11, unlike the above-described example, the positive external terminal 220 is separated from the lid 6, and the diaphragm 250 is provided integrally with the lid 6. An annular groove 6 d is provided on the outer surface (upper surface) of the lid 6 along the outer annular portion 51 of the diaphragm 250. The external terminal 220 has a flange portion 21 a that extends radially outward from the lower end portion of the peripheral wall portion 21. The flange portion 21a is fitted into the groove portion 6d of the lid 6, and is joined to the lid 6 by laser welding, for example.

Also in the example shown in FIG. 11, since the external terminal 220 and the lid 6 are at the same potential, it is not necessary to provide an insulating member between the lid 6 and the external terminal 220. Therefore, the airtightness can be easily ensured by joining the lid 6 and the external terminal 220 as described above.

Also in the example shown in FIG. 11, the diaphragm 250 is held by the lid 6 and is electrically connected to the external terminal 220 joined to the lid 6. The displacement part 55 of the diaphragm 250 is joined to the end face part 42 of the current collector 37 in the same manner as in the above-described example, thereby obtaining the same effect as described above.

As shown in FIG. 12, the welding operation of the diaphragm 50 and the current collector 37 is performed before the external terminal 220 is joined to the lid 6. Therefore, it is not necessary to provide the opening 22a as in the above-described example for avoiding interference with the jig in the plate-like portion 22 of the external terminal 220.

The welding operation shown in FIG. 12 is performed in a state where the lower gasket 32 and the current collector 37 are crimped and fixed to the lid 6 together with the discharge terminal 24 and the upper gasket 28 (see FIG. 11). The welding operation is performed in a posture in which the diaphragm 250 is disposed below the current collector 37. As a jig for welding work, a first jig 300 having a support pin 301 for supporting the displacement portion 55 of the diaphragm 250 from below and a second jig for pressing the base surface portion 38 of the current collector 37 from above. A jig 302 is used. The first jig 300 has a flat upper surface, and the support pins 301 protrude upward from the upper surface of the first jig 300.

When performing the welding operation, first, the lid 6 is placed on the upper surface of the first jig 300 so that the displacement portion 55 of the diaphragm 250 is supported from below by the upper end of the support pin 301. Subsequently, the end surface portion 42 is brought into close contact with the end surface portion 42 of the current collector 37 and the displacement portion 55 of the diaphragm 250 by pressing the base surface portion 38 of the current collector 37 from above with the second jig 302. A laser is irradiated from the upper side along the periphery of the opening 43 to weld the separation portion 46 of the end face portion 42 to the displacement portion 55 of the diaphragm 250.

The end surface portion 42 of the current collector 37 pressed against the support pin 301 through the displacement portion 55 of the diaphragm 250 during welding is provided at the tip of the protruding portion 40, and the entire outer periphery is supported by the protruding portion 40. Therefore, the stress from the support pin 301 can be received by the protrusion 40. Since the protruding portion 40 has a large thickness in the axial direction of the support pin 301, deformation due to stress from the support pin 301 hardly occurs. For this reason, current collection due to stress from the support pin 301 is compared to a case where a portion of the current collector 37 located on the same surface as the base surface portion 38 is pressed against the support pin 301 via the displacement portion 55 of the diaphragm 250. The deformation of the body 37 can be suppressed.

[Second Embodiment]
The configuration of a lithium ion secondary battery (hereinafter simply referred to as “battery”) 61 as a power storage element according to the second embodiment of the present invention will be described with reference to FIGS.

[overall structure]
Referring to FIGS. 13 to 15, the battery 61 includes an electrode body 62, an exterior body 64, positive and negative external terminals 70 and 80, positive and negative current collectors 77 and 90, upper gaskets 74 and 84, and a lower gasket 76. , 86, a tray member 100, and a current interrupting diaphragm (reversing film) 110.

The exterior body 64 includes a case main body 65 having an upper end and a lower end opened, an upper lid 66 that closes the upper end opening of the case main body 65, and a lower lid 67 that closes the lower end opening of the case main body 65. In the present embodiment, the case main body 65, the upper lid 66, and the lower lid 67 are made of aluminum or an aluminum alloy.

The case body 65 is, for example, a cylindrical member having an oval cross section. The upper lid 66 has a generally oval plate shape. The upper lid 66 is provided with a gas discharge valve 68 for discharging the gas generated in the case main body 65 to the outside of the exterior body 64. The lower lid 67 is provided along the outer edge of the base surface portion 67a, and extends upward from the base surface portion 67a. The base surface portion 67a has a generally oval plate shape, the bulging portion 67b bulges upward from the center of the base surface portion 67a. And an annular projecting portion 67c protruding from the surface. The cross-sectional shape of the bulging portion 67b is an oval shape that is long in the length direction of the base surface portion 67a. The annular convex portion 67c has an oval shape along the outer edge of the base surface portion 67a.

As shown in FIG. 14, the electrode body 62 is accommodated in a case main body 65 filled with an electrolytic solution. The electrode body 62 may be covered with an insulating sheet (not shown). In the case main body 65, lower gaskets 76 and 86, current collectors 77 and 90, and a tray member 100 are also accommodated.

The electrode body 62 is formed by superimposing two separators made of a positive and negative electrode sheet and a microporous resin sheet, each of which is a long strip with a constant width, and is wound into an elliptical shape with a generally high flatness. It is. The electrode sheet 62 of the electrode body 62 and the axis of winding of the separator (winding axis) are conceptually indicated by the symbol Y in FIG. The electrode body 62 is accommodated in the case body 65 in such a posture that the winding axis Y extends substantially in the axial direction of the case body 65 (vertical direction in FIG. 14).

At one end (upper side in FIG. 14) of the electrode body 62 in the extending direction of the winding axis Y, the negative electrode sheet protrudes from the positive electrode sheet and the separator, and the other (lower side in FIG. 14). The positive electrode sheet protrudes beyond the negative electrode sheet and the separator. The protruding portions of these electrode sheets are uncoated portions where no active material layer is provided on any surface of the metal foil. Thereby, the negative electrode lead part 62a formed by laminating only the metal foil of the negative electrode sheet is formed at one end (upper side in FIG. 14) of the electrode body 62 in the direction in which the winding axis Y extends. A positive electrode lead portion 62b formed by laminating only the metal foil of the positive electrode sheet is formed at the end portion (lower side in FIG. 14).

As shown in FIGS. 13 to 15, a negative external terminal 70 is disposed on one end side (the right side in FIGS. 13 to 15) of the upper lid 66, and the positive electrode exterior is disposed on the other end side (the left side in FIGS. 13 to 15). A terminal 80 is disposed. The external terminals 70 and 80 include plate- like portions 71 and 81 disposed on the outer side surface (upper side surface) of the upper lid 66. A connecting member such as a bus bar is welded to the plate- like portions 71 and 81 and connected to an external circuit.

The negative external terminal 70 includes a plate-like portion 71 disposed on the outer surface of the upper lid 66 and a columnar shaft portion 72 protruding downward from the lower surface of the plate-like portion 71. The shaft portion 72 is formed of a rivet separate from the plate-like portion 71. In this embodiment, the negative electrode external terminal 70 has a plate-like portion 71 made of aluminum or an aluminum alloy, and a shaft portion 72 made of copper or a copper alloy.

The shaft portion 72 passes through the upper gasket 74 and the upper lid 66 made of insulating resin and protrudes into the case main body 65. The lower gasket 76 made of insulating resin and the negative electrode current collector 77 are formed inside the case main body 65. It further penetrates (a base surface portion 78 described later). The upper gasket 74 is provided with a cylindrical portion 74 a (see FIG. 15) for inserting the shaft portion 72. The shaft portion 72 is provided on the upper cover 66, the lower gasket 76, and the base surface portion 78 of the current collector 77. Through holes 66a, 76a, 78a (see FIG. 15) for insertion are provided. A cylindrical portion 74 a of the upper gasket 74 is interposed between the inner peripheral surface of the through hole 66 a of the upper lid 66 and the outer peripheral surface of the shaft portion 72.

A diameter-expanded portion 72a (see FIG. 14) is formed by caulking at the lower end of the shaft portion 72 of the negative external terminal 70, whereby the negative external terminal 70 is caulked and fixed to the upper lid 66. Specifically, the upper gasket 74, the upper lid 66, the lower gasket 76, and the base surface portion 78 of the negative electrode current collector 77 are sandwiched between the plate-like portion 71 of the external terminal 70 and the enlarged diameter portion 72a. The negative external terminal 70 and the current collector 77 are fixed to the upper lid 66. An upper gasket 74 is interposed between the outer side surface (upper side surface) of the upper lid 66 and the external terminal 70, and a lower gasket 76 is interposed between the inner side surface (lower side surface) of the upper lid 66 and the current collector 77. It is disguised.

The positive external terminal 80 includes a plate-like portion 81 disposed on the outer surface of the upper lid 66, and a columnar shaft portion 82 that protrudes downward from the lower surface of the plate-like portion 81. The shaft part 82 is formed integrally with the plate-like part 81. In the present embodiment, the positive external terminal 80 is made of aluminum or an aluminum alloy.

The shaft portion 82 penetrates the upper gasket 84 and the upper lid 66 made of an insulating resin and protrudes into the case main body 65. In the case main body 65, the lower gasket 86 made of an insulating resin and the positive electrode current collector 90 are formed. It further penetrates (base surface portion 92 described later). The upper gasket 84 is provided with a cylindrical portion 84 a (see FIG. 15) for inserting the shaft portion 82. The shaft portion 82 is provided on the upper cover 66, the lower gasket 86, and the base surface portion 92 of the current collector 90. Through holes 66b, 87b, 92a (see FIG. 15) for insertion are provided. A cylindrical portion 84 a of the upper gasket 84 is interposed between the inner peripheral surface of the through hole 66 b of the upper lid 66 and the outer peripheral surface of the shaft portion 82.

The enlarged diameter part 82a (refer FIG. 14) is formed in the lower end of the axial part 82 by caulking. As a result, the negative external terminal 80 is crimped and fixed to the upper lid 66. Specifically, the upper gasket 84, the upper lid 66, the lower gasket 86, and the base surface portion 92 of the positive electrode current collector 90 are sandwiched between the plate-like portion 81 of the external terminal 80 and the enlarged diameter portion 82a. The negative external terminal 80 and the current collector 90 are fixed to the upper lid 66. An upper gasket 84 is interposed between the outer surface of the upper lid 66 and the external terminal 80, and a lower gasket 86 is interposed between the inner surface of the upper lid 66 and the positive electrode current collector 90.

The negative electrode current collector 77 includes a base surface portion 78 fixed to the upper lid 66 and a current collector portion 79 extending downward from the base surface portion 78. The negative electrode current collector 77 is made of copper or a copper alloy. As described above, the base surface portion 78 is caulked and fixed to the upper lid 66 by the enlarged diameter portion 72a formed in the shaft portion 72 of the negative external terminal 70. The current collector 79 is welded to the negative electrode lead 62 a of the electrode body 62 and is electrically and mechanically connected. Thus, the negative electrode lead portion 62a of the electrode body 62 is electrically connected to the negative electrode external terminal 70 via the negative electrode current collector 77.

The bulging portion 67 b of the lower lid 67 is welded to the positive electrode lead portion 62 b of the electrode body 62 and is electrically and mechanically connected. Thereby, the exterior body 64 is electrically connected to the positive electrode lead portion 62 b of the electrode body 62. Since the exterior body 64 and the positive electrode lead portion 62b are at the same potential as described above, in order to prevent energization between the case body 65 and the negative electrode current collector 77, the negative electrode current collector 77 and A spacer (not shown) made of an insulating material is preferably interposed between the case body 65 and the case body 65.

The positive electrode current collector 90 is made of aluminum or an aluminum alloy. The positive electrode current collector 90 also has a base surface portion 92 fixed to the upper lid 66. As described above, the base surface portion 92 is caulked and fixed to the upper lid 66 by the enlarged diameter portion 82a formed in the shaft portion 82 of the positive external terminal 80.

The positive electrode collector 90 is a conductive member provided in a conductive path between a later-described current-blocking diaphragm 110 and a positive external terminal 80, and is electrically connected to the exterior body 64 through the diaphragm 110. Further, it is electrically connected to the positive electrode lead portion 62 b of the electrode body 62 through the exterior body 64.

Thus, the positive external terminal 80 is electrically connected to the positive lead portion 62b of the electrode body 62 through the current collector 90, the diaphragm 110, and the exterior body 64.

Hereinafter, the configuration of the diaphragm 110 and the more specific configuration of the positive electrode current collector 90, the lower gasket 86, and the tray member 100 related thereto will be described.

[Diaphragm for current interruption and related structure]
As shown in FIGS. 16 to 18, the diaphragm 110 is joined to the upper lid 66 at the outer peripheral portion thereof. The upper lid 66 is provided with an opening 66c at a portion where the diaphragm 110 is joined. The shape of the opening 66 c is, for example, an oval shape that is long in the short direction of the upper lid 66. An annular notch 66d is provided at a corner portion between the inner peripheral surface of the opening 66c and the inner side surface (lower surface) of the upper lid 66.

The diaphragm 110 includes a conductive path between the positive electrode lead portion 62b of the electrode body 62 and the positive electrode external terminal 80, more specifically, an exterior body 64 electrically connected to the positive electrode lead portion 62b, and an external terminal 80. This is a conductive member provided in a conductive path between the current collector 90 and the current collector 90 electrically connected to the current collector. That is, the diaphragm 110 is electrically connected to the external terminal 80 via the current collector 90 and electrically connected to the positive electrode lead portion 62 b of the electrode body 62 via the exterior body 64. The diaphragm 110 is made of, for example, aluminum or an aluminum alloy.

The diaphragm 110 includes an outer annular portion 111 that forms an outer periphery thereof, a displacement portion 113 that can be displaced to a predetermined position toward the outside of the exterior body 64 by an increase in internal pressure of the exterior body 64, and a radially outer side from the outer edge of the displacement portion 113. And a flare portion 112 extending to the outer annular portion 111. The contours of the outer annular portion 111, the flare portion 112, and the displacement portion 113 are, for example, oval, but the shapes of these contours are not particularly limited.

The outer peripheral portion of the outer annular portion 111 of the diaphragm 110 is fitted into the notch 66 d of the upper lid 66. The inner side surface (lower side surface) of the outer annular portion 111 is disposed on the same plane as the inner side surface of the upper lid 66. The outer annular portion 111 is joined to the upper lid 66 by laser welding, for example. Laser welding is performed over the entire circumference along the outer edge of the outer annular portion 111 by, for example, laser irradiation from below. In this way, the diaphragm 110 is joined to the upper lid 66, whereby the opening 66 c of the upper lid 66 is closed from the lower side by the diaphragm 110. The diaphragm 110 is held by the exterior body 64 by mechanical connection with the upper lid 66, and is electrically connected to the positive electrode lead portion 62 b of the electrode body 62 via the exterior body 64. The diaphragm 110 may be provided integrally with the upper lid 66.

In a normal time when the internal pressure of the exterior body 64 is less than a predetermined pressure, the displacement portion 113 of the diaphragm 110 is disposed on the inner side (lower side) of the outer annular portion 111. The flare part 112 connects the outer edge of the displacement part 113 and the inner edge of the outer annular part 111. In a normal time when the internal pressure of the exterior body 64 is less than a predetermined pressure, the flare portion 112 is disposed to be inclined toward the inner space side of the exterior body 64 toward the inside in the radial direction.

As described above, the diaphragm 110 is provided on the upper lid 66, and at least the outer annular portion 111 of the diaphragm 110 is provided so as to overlap the upper lid 66 in the thickness direction. As described above, the outer annular portion 111 of the diaphragm 110 is arranged outside the inner side surface (lower side surface) of the upper lid 66, so that the entire diaphragm 110 after the inversion is outside the inner side surface of the upper lid 66. Will be placed. Therefore, compared with the case where the entire diaphragm 110 is disposed on the inner side (lower side) of the upper lid 66, a larger layout space of the electrode body 62 in the inner space of the exterior body 64 can be secured, and the height of the battery 61 can be increased. Capacity can be increased.

Subsequently, with reference to FIGS. 15 to 18, a more specific configuration related to the diaphragm 110 regarding the positive electrode current collector 90, the lower gasket 86, and the tray member 100 will be described.

The lower gasket 86 has a base surface portion 87 that is sandwiched between the upper lid 66 and the base surface portion 92 of the current collector 90. The shape of the base surface portion 87 is, for example, a semi-oval shape that is long in the length direction of the upper lid 66. The base surface portion 87 is provided with an opening 87 a at a position corresponding to the diaphragm 110. The shape of the opening 87 a is, for example, an oval shape that is long in the short direction of the upper lid 66. With respect to the longitudinal direction of the upper lid 66, the opening 87a of the lower gasket 86 and the opening 66c of the upper lid 66 have the same dimensions, and the inner peripheral surfaces of the straight portions of these openings 66c and 87a are arranged on the same plane. Has been.

The lower gasket 86 further includes a peripheral wall portion 88 protruding downward from the outer edge of the base surface portion 87. A plurality of engaging projections 88 a that are engaged with the tray member 100 are provided on the outer peripheral surface of the peripheral wall portion 88.

The tray member 100 has a catch surface portion 102 that is disposed opposite to the inner side (lower side) of the lower gasket 86 with the current collector 90 interposed therebetween. The shape of the catch surface portion 102 is, for example, a quadrangular shape. The catch surface portion 102 is disposed in parallel to the base surface portion 87 of the lower gasket 86. The tray member 100 further includes a pair of rising surface portions 103 and 104 extending from the periphery of the catch surface portion 102 toward the outside (upper side). The pair of rising surface portions 103 and 104 are disposed so as to face each other. Each of the rising surface portions 103 and 104 is provided with an engagement hole 105 that is engaged with the engagement convex portion 88 a of the lower gasket 86. The tray member 100 is held by the lower gasket 86 by the engagement between the engagement hole 105 and the engagement protrusion 88a.

The shape of the base surface portion 92 of the current collector 90 is, for example, a semi-oval shape that is long in the length direction of the upper lid 66. The base surface portion 92 is disposed so as to overlap the inner side (lower side) of the base surface portion 87 of the lower gasket 86 in the internal space of the exterior body 64. The base surface portion 92 is disposed so as to face the inner side (lower side) of the diaphragm 110 through the opening 87 a of the lower gasket 86. The outer edge of the base surface portion 92 is disposed opposite to the inner peripheral surface of the peripheral wall portion 88 of the lower gasket 86, whereby the current collector 90 can be positioned with respect to the lower gasket 86.

At a position corresponding to the diaphragm 110 in the base surface portion 92 of the current collector 90, a protruding portion 94 protruding toward the diaphragm 110 and an end surface portion 96 provided at the tip of the protruding portion 94 are provided. The protruding portion 94 protrudes from the base surface portion 92 in a conical shape. The end surface portion 96 has a circular shape and is disposed in parallel to the base surface portion 92. Thereby, a truncated cone having the projecting portion 94 as a side surface and the end surface portion 96 as an upper surface is formed. The protrusion 94 is disposed in the opening 87 a of the lower gasket 86, thereby preventing interference between the protrusion 94 and the lower gasket 86. An opening 97 is provided at the center of the end surface portion 96.

In particular, as shown in FIGS. 17 and 18, the end surface portion 96 is provided with an endless cutting portion 98. Thus, the end surface portion 96 is divided into a separation portion 96 a surrounded by the cutting portion 98 and an outer peripheral portion 96 b surrounding the separation portion 96 a via the cutting portion 98. The separating part 96 a can be separated from the current collector 90 along the cutting part 98. The cutting part 98 is formed in a circular shape, for example. A cut is formed in the cut portion 98, whereby the cut portion 98 is easier to break than the portion other than the cut portion 98 in the end face portion 96. The cutting part 98 is formed into a thin part by forming a half-cut cut continuous over the entire circumference. The cut of the cutting part 98 is preferably formed on the inner side surface (lower surface) of the end surface part 96. In addition, the cut of the cutting part 98 may be a full cut that penetrates the end face part 96 in the thickness direction. In this case, the full cut is provided in a perforated pattern intermittently in the circumferential direction.

The end surface portion 96 is disposed in the opening 87 a of the base surface portion 87 of the lower gasket 86. The end surface portion 96 is joined to the displacement portion 113 of the diaphragm 110 at the separation portion 96a. The separation portion 96 a is an annular portion outside the opening 97 and inside the cutting portion 98 in the end surface portion 96. The separation part 96a is joined to the outer peripheral part of the displacement part 113 by welding performed along the periphery of the opening 97, for example.

The portion of the displacement portion 113 that is radially inward of the joint portion with the separation portion 96 a faces the internal space of the exterior body 64 through the opening 97 of the end surface portion 96. As a result, the displacement portion 113 always receives the internal pressure of the exterior body 64 directly, but in a normal time when the internal pressure is less than a predetermined pressure, the displacement portion 113 is joined by the separation portion 96a of the current collector 90. The lower gasket 86 is held at a predetermined position in the opening 87a.

When the internal pressure of the exterior body 64 rises to a predetermined pressure or more due to generation of gas due to overheating of the electrode body 62, the diaphragm 110 is deformed so as to be reversed, as shown by the two-dot chain line in FIG. The displacement part 113 is displaced to a predetermined position toward the outside of the exterior body 64. At this time, the displacement portion 113 and the separation portion 96a of the current collector 90 joined to the displacement portion 113 are displaced in the direction away from the base surface portion 92 of the current collector 90 toward the outside of the exterior body 64. The separating part 96 a is separated from the remaining part of the current collector 90 along the cutting part 98.

At this time, the displacement portion 113 is displaced from a position protruding inward (downward) from the outer annular portion 111 to a position protruding outward (upward) from the outer annular portion 111. Further, by inverting the diaphragm 110 in this manner, the flare portion 112 of the diaphragm 110 is disposed to be inclined toward the outer space side of the exterior body 64 toward the inside in the radial direction.

Since the protruding portion 94 of the current collector 90 protrudes toward the diaphragm 110 (the outer space side of the exterior body 64) with respect to the base surface portion 92 from the beginning, the separating portion 96a is separated from the current collector 90 as described above. Therefore, when the protrusion 94 is pulled toward the diaphragm 110 by the separating portion 96a when it is going to be displaced toward the external space, the protrusion 94 is unlikely to be deformed so as to protrude further toward the diaphragm 110. Therefore, the current collector 90 can be maintained in a state where the entire current collector 90 is located on the inner side (lower side) of the diaphragm 110, and the current collector 90 can be reliably prevented from coming into contact with the diaphragm 110 inverted as described above. Thereby, after reversing the diaphragm 110, the energization between the diaphragm 110 and the current collector 90, and thus the energization between the external terminal 80 of the positive electrode and the positive electrode lead portion 62b of the electrode body 62 can be reliably interrupted. The current interruption performance of the battery 61 is improved. Therefore, further charging of the battery 61 is avoided, so that it is easy to suppress further heat generation and gas generation of the electrode body 62, thereby easily avoiding the release of gas through the gas discharge valve 68.

The displaced part 113 and the flare part 112 of the diaphragm 110 after the inversion are accommodated in the space in the opening 66c of the upper lid 66. Therefore, it is not necessary to secure a space for housing the inverted diaphragm 110 in the case main body 65, and a large layout space for the electrode body 62 in the case main body 65 can be ensured. High capacity can be achieved.

The catch surface portion 102 of the tray member 100 is disposed close to the inside (lower side) of the protruding portion 94 and the end surface portion 96 of the current collector 90. When a large current flows into the current collector 90 due to an external short circuit or the like when the diaphragm 110 is not inverted, that is, when the current can flow between the diaphragm 110 and the current collector 90, the end face of the current collector 90 The part 96 is fused at the cutting part 98. The metal piece that falls due to this fusing is received by the catch surface portion 102 of the tray member 100.

FIG. 19 is a schematic diagram showing the dimensions of each part of the diaphragm 110 and the current collector 90. Note that a two-dot chain line in FIG. 19 indicates the diaphragm 110 in an inverted state.

As shown in FIG. 19, the thickness L1 of the end surface portion 96 of the current collector 90, the thickness L2 of the protruding portion 94, and the thickness L3 of the base surface portion 92 are preferably set in the same manner as in the first embodiment (FIG. 8). reference). In addition, the protrusion amount L4 of the protrusion 94 from the base surface portion 92 in the current collector 90, and the radial dimension L5 from the corner portion to the cutting portion 98 between the inner peripheral surface of the protrusion 94 and the end surface portion 96 of the current collector 90. The displacement amount L6 from the normal position of the displacement portion 113 of the diaphragm 110 to the position after inversion is preferably set in the same manner as in the first embodiment (see FIG. 8). Thereby, the contact between the diaphragm 110 after reversal and the current collector 90 is reliably prevented, and the current interruption performance of the battery 61 is improved.

In the second embodiment, the method for welding the diaphragm 110 and the current collector 90 is not limited. For example, the same jig as shown in FIG. 12 is used as in the modification of the first embodiment. 300, 302 can be used for welding.

In the second embodiment, various changes can be made to the configuration of the diaphragm 110. For example, the diaphragm 110 may be provided with a cylindrical portion 52 and an enlarged diameter portion 53 similar to the diaphragm 50 of the first embodiment between the outer annular portion 111 and the flare portion 112. Further, the displacement portion 113 of the diaphragm 110 is fitted with a fitting portion 154 (see FIG. 10) fitted in the opening portion 97 of the end surface portion 96 of the current collector 90, as in the modification shown in FIG. 10 of the first embodiment. ) May be provided.

As mentioned above, although the present invention has been described with reference to the above embodiment, the present invention is not limited to the above embodiment.

For example, in the above embodiment, the example in which the diaphragm for interrupting current is provided on the lid of the exterior body has been described. However, in the present invention, the diaphragm may be provided on a portion other than the lid on the exterior body.

In the above embodiment, the example in which the diaphragm displacement portion is joined to the current collector has been described. However, in the present invention, the diaphragm displacement portion may be joined to a conductive member other than the current collector.

Furthermore, although the above embodiment demonstrated the example which the protrusion part of the electrical power collector (conductive member) protruded in the shape of a cone from the base surface part, in this invention, the protrusion part of a conductive member is cylindrical from the base surface part. You may provide so that it may protrude.

Furthermore, in the above-described embodiment, the power storage element according to the present invention has been described by taking a lithium ion secondary battery as an example. However, the present invention includes various secondary batteries other than lithium ion secondary batteries, primary batteries, and capacitors. It can be applied to the electricity storage element.

1 Battery (storage element)
DESCRIPTION OF SYMBOLS 2 Electrode body 2a Negative electrode lead part 2b Positive electrode lead part 4 Exterior body 5 Case main body 6 Lid 8 Gas exhaust valve 10 Negative electrode external terminal 14 Upper gasket 16 Lower gasket 17 Negative electrode collector 20 Positive electrode external terminal (external body terminal) Bulge)
24 Discharge terminal 28 Upper gasket 32 Lower gasket 37 Current collector of positive electrode (conductive member)
38 Base surface portion 39a, 39b Leg portion 40 Protruding portion 42 End surface portion 43 Opening portion 45 Cutting portion 46 Detaching portion 47 Outer peripheral portion 50 Diaphragm 51 Outer annular portion 52 Cylindrical portion 53 Expanded portion 53a First annular portion 53b Connecting portion 53c First 2 annular part 54 flare part 55 displacement part 61 battery (storage element)
62 Electrode body 62a Negative electrode lead portion 62b Positive electrode lead portion 64 Exterior body 65 Case body 66 Upper lid 66c Opening portion 67 Lower lid 68 Gas discharge valve 70 Negative electrode external terminal 74 Upper gasket 76 Lower gasket 77 Negative electrode collector 80 Positive electrode collector External terminal 84 Upper gasket 86 Lower gasket 87 Base surface portion 87a Opening 90 Current collector of positive electrode (conductive member)
92 Base surface portion 94 Projection portion 96 End surface portion 96a Separation portion 96b Outer peripheral portion 97 Opening portion 98 Cutting portion 100 Tray member 110 Diaphragm 111 Outer annular portion 112 Flare portion 113 Displacement portion 150 Diaphragm 154 Fitting portion 250 Diaphragm 220 Positive electrode external terminal

Claims (7)

1. An exterior body that houses the electrode body;
   An external terminal provided outside the exterior body;
   A displacement portion that can be displaced to a predetermined position toward the outside of the exterior body by an increase in internal pressure of the exterior body, and a diaphragm provided in a conductive path between the electrode body and the external terminal;
   A base surface portion disposed oppositely to the inside of the diaphragm in the exterior body, a projecting portion projecting in a conical or cylindrical shape from the base surface portion toward the diaphragm, and a tip of the projecting portion. An electrical storage element comprising: an end surface portion joined to the displacement portion, and a conductive member provided in a conductive path between either the electrode body or the external terminal and the diaphragm.
2. The electrical storage element according to claim 1, wherein a cut portion surrounding the joint portion with the displacement portion is provided on the end surface portion of the conductive member.
3. The radial dimension from the corner portion between the inner peripheral surface of the projecting portion and the end surface portion of the conductive member to the cut portion is smaller than the displacement amount of the displacement portion of the diaphragm to the predetermined position. 2. The electricity storage device according to 2.
4. The electric storage element according to any one of claims 1 to 3, wherein at least a part of the diaphragm is disposed outside an inner side surface of the exterior body.
5. The exterior body includes a hollow bulging portion that bulges outward from a predetermined surface portion of the exterior body,
   The storage element according to claim 4, wherein an accommodation space for accommodating the displacement portion of the diaphragm displaced to the predetermined position is formed inside the bulging portion.
6. The thickness of the protruding portion of the conductive member is greater than the thickness of the end surface portion of the conductive member,
   The electrical storage element according to any one of claims 1 to 5, wherein a thickness of the base surface portion of the conductive member is equal to or greater than a thickness of the protruding portion.
7. An opening is provided in the end surface portion of the conductive member,
   The power storage element according to claim 1, wherein the displacement portion of the diaphragm has a fitting portion that fits into the opening.

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