JP2017004640A - Secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly safe secondary battery. A secondary battery according to one embodiment is a secondary battery in which an outer can and a lid are welded to form an outer material, and includes an electrode group, a first current collecting tab, and a first collector tab. The second current collecting tab, the first terminal, the second terminal, the first lead, the second lead, and the short-circuit member. In the electrode group, the positive electrode and the negative electrode, which are stacked via the separator, are wound in a flat shape and housed in the exterior material. The first lead is provided in the outer can and connects the first terminal and the first current collecting tab. The second lead is provided in the outer can and connects the second terminal and the second current collecting tab. The short-circuit member short-circuits the first lead and the second lead when an external force is applied to the electrode group. [Selection diagram]

Description

  Embodiments described herein relate generally to a secondary battery.

  In recent years, automobiles using a secondary battery as an energy source have been put into practical use due to the reduction of carbon dioxide emissions and the fear of exhaustion of fossil fuels such as gasoline. The secondary battery is required to have high output, high energy density, small size, light weight, low price, etc., and improvement in safety and durability is indispensable.

  Lithium ion secondary batteries are known as high energy density secondary batteries for automobiles. This high energy density lithium ion secondary battery typically includes an electrode assembly including an electrode group in which a positive electrode and a negative electrode wound around a separator are wound and impregnated with an organic electrolyte and enclosed in a battery can. It is.

  The secondary battery is ignited by thermal runaway caused by a short circuit between the positive electrode active material and the negative electrode active material of the electrode group in the outer can due to deformation (crushing) due to external force damage (collapse). there is a possibility. Therefore, there is a secondary battery that is short-circuited at a position where no active material is applied before the active material of the positive electrode and the active material of the negative electrode of the electrode group are short-circuited when an external force is applied to the secondary battery.

JP-A-10-261429

  When an external force is applied to the electrode group, there is a problem that the positive electrode active material and the negative electrode active material of the electrode group are more preferably short-circuited at a location where no active material is applied before the short-circuit.

  In order to solve the above problems, a highly safe secondary battery is provided.

  A secondary battery according to an embodiment is a secondary battery in which an exterior can and a lid are welded to form an exterior material, the electrode group, a first current collecting tab, and a second current collecting A tab, a first terminal, a second terminal, a first lead, a second lead, and a short-circuit member are provided. In the electrode group, a positive electrode and a negative electrode which are stacked via a separator are wound into a flat shape and accommodated in the exterior material. The first lead is provided in the outer can and connects the first terminal and the first current collecting tab. The second lead is provided in the outer can and connects the second terminal and the second current collecting tab. The short-circuit member short-circuits the first lead and the second lead when an external force is applied to the electrode group.

FIG. 1 is a diagram for explaining a configuration example of an electrode assembly of a secondary battery according to an embodiment. FIG. 2 is a diagram for explaining a configuration example of a secondary battery according to an embodiment. FIG. 3 is a diagram for explaining an example of a partial cross section of the secondary battery according to the embodiment. FIG. 4 is a diagram for explaining an example of a partial cross section of the secondary battery according to the embodiment. FIG. 5 is a diagram for explaining an example of a partial cross section of the secondary battery according to the embodiment. FIG. 6 is a diagram for explaining another example of a partial cross section of the secondary battery according to the embodiment. FIG. 7 is a diagram for explaining another example of a partial cross section of the secondary battery according to the embodiment. FIG. 8 is a diagram for explaining another example of a partial cross section of the secondary battery according to the embodiment.

Hereinafter, description will be given with reference to the drawings.
FIG. 1 shows a configuration example of an electrode assembly 10 according to an embodiment. FIG. 2 shows a configuration example of the secondary battery 1 in which the electrode assembly 10 is accommodated in the outer can 30.

  The electrode assembly 10 includes an electrode group 11, a positive current collecting tab (first current collecting tab) 12, a negative electrode current collecting tab (second current collecting tab) 13, a lid 20, and a positive electrode terminal (first terminal) 22. , A negative electrode terminal (second terminal) 23, a gasket 24, a positive electrode lead (first lead) 26, and a negative electrode lead (second lead) 27. Further, the electrolyte is held in the electrode group 11. The electrolyte is a nonaqueous electrolyte, for example.

  The secondary battery 1 includes an electrode assembly 10 and an outer can 30. The secondary battery 1 is manufactured by housing the electrode assembly 10 in the outer can 30, welding the lid 20 to the outer can 30, and injecting an organic electrolyte into the outer can 30.

  The electrode group 11 is a laminate in which a positive electrode, a negative electrode, and a separator sandwiched between the positive electrode and the negative electrode are stacked and wound in a flat shape around a winding axis. The positive electrode is a positive current collector excluding, for example, a strip-shaped positive current collector made of metal foil, a positive current collector tab 12 having one end parallel to the long side of the positive current collector, and at least the positive current collector tab 12 portion. A positive electrode material layer (positive electrode active material-containing layer) formed on the electric body. On the other hand, the negative electrode is, for example, except for a strip-shaped negative electrode current collector made of a metal foil, a negative electrode current collector tab 13 having one end parallel to the long side of the negative electrode current collector, and at least a portion of the negative electrode current collector tab 13. A negative electrode material layer (negative electrode active material-containing layer) formed on the negative electrode current collector.

  Such a positive electrode, a separator, and a negative electrode are arranged so that the positive electrode current collecting tab 12 protrudes from the separator in the winding axis direction of the electrode group 11 and the negative electrode current collecting tab 13 protrudes from the separator in the opposite direction. And it is wound by shifting the position of the negative electrode. By such winding, the electrode group 11 has the positive electrode current collecting tab 12 wound in a spiral shape from one end face protrudes in the winding axis direction of the electrode group 11 and winds in a spiral form from the other end face. The negative electrode current collector tab 13 thus protrudes in the winding axis direction of the electrode group 11.

  In the following directions, the direction parallel to the winding axis direction of the electrode group 11 is the X direction, the direction parallel to the thickness direction of the electrode group 11 is the Y direction, and the direction perpendicular to the directions X and Y is Z. It is called a direction.

Hereinafter, the positive electrode, the negative electrode, the separator, and the nonaqueous electrolyte will be described.
The positive electrode is produced, for example, by applying a slurry containing a positive electrode active material to a current collector made of an aluminum foil or an aluminum alloy foil. Although it does not specifically limit as a positive electrode active material, The oxide, sulfide, polymer, etc. which can occlude / release lithium can be used. Preferable active materials include lithium manganese composite oxide, lithium nickel composite oxide, lithium cobalt composite oxide, lithium iron phosphate, and the like that can obtain a high positive electrode potential.

  The negative electrode is produced by applying a slurry containing a negative electrode active material to a current collector made of an aluminum foil or an aluminum alloy foil. The negative electrode active material is not particularly limited, and metal oxides, metal sulfides, metal nitrides, alloys, and the like that can occlude and release lithium can be used. Preferably, the lithium ion occlusion and release potential is metal lithium. It is a substance that becomes noble 0.4V or more with respect to the potential. Since the negative electrode active material having such a lithium ion storage / release potential can suppress the alloy reaction between aluminum or an aluminum alloy and lithium, it is possible to use aluminum or an aluminum alloy for a negative electrode current collector and a negative electrode related component. And For example, there are titanium oxide, lithium titanium composite oxide such as lithium titanate, tungsten oxide, amorphous tin oxide, tin silicon oxide, silicon oxide, etc. Among them, lithium titanium composite oxide is preferable. As the separator, a microporous film, a woven fabric, a non-woven fabric, a laminate of the same material or different materials among these can be used.

  Examples of the material for forming the separator include polyethylene, polypropylene, ethylene-propylene copolymer, and ethylene-butene copolymer.

As the electrolytic solution, a nonaqueous electrolytic solution prepared by dissolving an electrolyte (for example, lithium salt) in a nonaqueous solvent is used. Examples of the non-aqueous solvent include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), γ-butyrolactone (γ -BL), sulfolane, acetonitrile, 1,2-dimethoxyethane, 1,3-dimethoxypropane, dimethyl ether, tetrahydrofuran (THF), 2-methyltetrahydrofuran and the like. Nonaqueous solvents may be used alone or in combination of two or more. Examples of the electrolyte include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium hexafluoroarsenide (LiAsF ₆ ), and trifluorometa. A lithium salt such as lithium sulfonate (LiCF ₃ SO ₃ ) can be given. The electrolyte may be used alone or in combination of two or more. The amount of electrolyte dissolved in the non-aqueous solvent is desirably 0.2 mol / L to 3 mol / L.

  The lid 20 is made of a conductive metal. The lid 20 is formed in substantially the same size as the opening of the bottomed rectangular tube-shaped outer can 30 having conductivity, and is formed so as to at least close the opening. The lid 20 is disposed at the opening of the bottomed rectangular tube-shaped outer can 30 having conductivity and is welded to the outer can 30. By thus welding the lid 20 and the outer can 30, an outer packaging material in which the electrode assembly 10 is enclosed is formed. The lid 20 includes a hole through which the positive electrode terminal 22 passes and a hole through which the negative electrode terminal 23 passes. The lid 20 fixes the positive terminal 22 and the negative terminal 23 through gaskets 24 that are insulating members installed in the holes.

  The lid 20 can be formed from, for example, aluminum or an aluminum alloy. As the aluminum alloy, an alloy containing an element such as manganese, iron, copper, silicon, or zinc is preferable.

  The positive electrode terminal 22 and the negative electrode terminal 23 are interfaces for supplying electric power stored in the electrode group 11 of the secondary battery 1 to the outside. The positive terminal 22 and the negative terminal 23 are provided so as to protrude from the lid 20. The positive terminal 22 is electrically connected to the positive current collecting tab 12 via a positive lead 26. Further, the negative electrode terminal 23 is electrically connected to the negative electrode current collecting tab 13 through an internal negative electrode lead 27.

  The positive lead 26 connects the positive terminal 22 and the positive current collecting tab 12. For example, a part of the positive electrode lead 26 may be formed as the positive electrode terminal 22, and the end of the positive electrode lead 26 may be connected to the positive electrode current collecting tab 12. The negative electrode lead 27 connects the negative electrode terminal 23 and the negative electrode current collecting tab 13. For example, a part of the negative electrode lead 27 may be formed as the negative electrode terminal 23, and the end of the negative electrode lead 27 may be connected to the negative electrode current collecting tab 13.

  The positive electrode lead 26 is fixed to the lid 20 by caulking the connected positive electrode terminal 22 to the lid 20. The negative electrode lead 27 is fixed to the lid 20 when the connected negative electrode terminal 23 is caulked to the lid 20. As described above, the positive electrode lead 26 is connected to the positive electrode terminal 22 and the positive electrode current collecting tab 12, and the negative electrode lead 27 is connected to the negative electrode terminal 23 and the negative electrode current collecting tab 13, thereby producing the electrode assembly 10. .

  In the case of a lithium ion secondary battery in which a carbon-based material is used as the negative electrode active material, the positive electrode terminal 22 is generally made of aluminum or an aluminum alloy. The negative electrode terminal 23 is made of a metal such as copper, nickel, or nickel-plated iron. When lithium titanate is used as the negative electrode active material, aluminum or an aluminum alloy may be used for the negative electrode terminal 23 in addition to the above metal. When aluminum or an aluminum alloy is used for the positive electrode terminal 22 and the negative electrode terminal 23, the positive electrode current collecting tab 12, the negative electrode current collecting tab 13, the positive electrode lead 26, and the negative electrode lead 27 are made of aluminum or an aluminum alloy. Is desirable. For example, an aluminum alloy containing at least one element selected from the group consisting of Al, Mg, Ti, Zn, Mn, Fe, Cu, and Si is used.

  The outer can 30 is formed of a bottomed rectangular tube-shaped metal having conductivity. The outer can 30 can be formed from, for example, aluminum or an aluminum alloy. As the aluminum alloy, an alloy containing an element such as manganese, iron, copper, silicon, or zinc is preferable. The plate thickness of the outer can 30 can be 1 mm or less, and more preferably 0.2 to 0.7 mm.

  The electrode assembly 10 manufactured as described above is loosely inserted in the Z direction with respect to the opening of the outer can 30 with the electrode group 11 as the head. Further, the side edge of the lid 20 and a part of the opening of the outer can are welded by, for example, a welding method such as laser welding while the lid 20 is in contact with the opening of the outer can 30. As a result, the electrode assembly 10 is enclosed in the exterior material by the lid 20 and the exterior can 30. Further, the secondary battery 1 is ready for use by injecting an organic electrolyte into the exterior material.

FIG. 3 shows an example of a cross-sectional view when the secondary battery 1 of FIG. 2 is cut along an AA line.
The positive electrode lead 26 and the negative electrode lead 27 are fixed to the inner surface side of the lid 20 via an insulating layer formed by an insulator 28 or a gap 29, respectively. The insulator 28 is an insulating member, and is formed of, for example, an insulating resin. The air gap 29 is a space provided between the positive electrode lead 26 and the negative electrode lead 27 and the lid 20. That is, at the position facing the gap 29, the inner surface of the lid 20 is exposed. According to the example of FIG. 3, the insulator 28 is formed with a thickness T. The gap 29 is formed so that the lid 20 and the positive electrode lead 26 or the negative electrode lead 27 are separated from each other by a distance T, like the insulator 28. That is, the insulating layer formed by the gap 29 or the insulator 28 is formed with a thickness T in the Z direction.

  The positive electrode lead 26 includes a lead part (first lead part) 26a and an extension part (first extension part) 26b. The lead part 26 a is a member that electrically connects the positive electrode terminal 22 and the positive electrode current collecting tab 12. The lead portion 26a extends in the Z direction from the position where the positive electrode terminal 22 is connected toward the electrode group 11 side. As a result, the lead part 26 a is disposed in the vicinity of the positive electrode current collecting tab 12 of the electrode group 11. Furthermore, the lead part 26 a is electrically connected to the positive electrode current collector tab 12 and the positive electrode of the electrode group 11 by being welded to the positive electrode current collector tab 12. The extending part 26b extends in the X direction from the position where the positive electrode terminal 22 is connected toward the negative electrode terminal 23 side. The extending portion 26b extends in the X direction from the position where the positive terminal 22 is connected toward the negative terminal 23 side. According to the example of FIG. 3, the extending portion 26 b is formed to extend from the position in contact with the end portion of the insulator 28 with a length L toward the gap 29 side.

  The negative electrode lead 27 includes a lead part (second lead part) 27a and an extension part (second extension part) 27b. The lead portion 27 a is a member that electrically connects the negative electrode terminal 23 and the negative electrode current collecting tab 13. The lead portion 27a extends in the Z direction from the position where the negative electrode terminal 23 is connected toward the electrode group 11 side. As a result, the lead portion 27 a is disposed in the vicinity of the negative electrode current collecting tab 13 of the electrode group 11. Furthermore, the lead portion 27 a is electrically connected to the negative electrode current collector tab 13 and the negative electrode of the electrode group 11 by being welded to the negative electrode current collector tab 13. The extending portion 27b extends in the X direction from the position where the negative electrode terminal 23 is connected toward the positive electrode terminal 22 side. The extending portion 27b extends in the X direction from the position where the negative electrode terminal 23 is connected toward the positive electrode terminal 22 side. According to the example of FIG. 3, the extending portion 27 b is formed to extend with a length L from the position in contact with the end portion of the insulator 28 toward the gap 29 side.

  The extension part 26b and the extension part 27b are formed so as to come into contact with the inner surface of the lid 20 when an external force is applied to the secondary battery 1 and the lid 20 as the exterior material is deformed. Further, the extension part 26 b and the extension part 27 b are formed so as to be bent by the electrode group 11 and contact the lid 20 when an external force is applied to the secondary battery 1 and the electrode group 11 is deformed. .

  The electrode group 11 has lower rigidity on the side surface parallel to the winding axis than on the surface orthogonal to the winding axis, that is, the surface on which the tab is provided. For this reason, when an external force is applied to the electrode group 11, the side surface of the electrode group 11 is more easily deformed than the surface on which the tab is provided. That is, the electrode group 11 is easily deformed in the Y direction or the Z direction from the X direction when an external force is applied. In addition, since the deformation | transformation to the Y direction of the electrode group 11 is suppressed by the inner surface of the armored can 30 when accommodated in the armored can 30, the electrode group 11 is the lid | cover 20 with which the space is provided in the Z direction. Easy to deform toward the side. Therefore, the extension part 26b and the extension part 27b are bent in accordance with the deformation of the electrode group 11 when the electrode group 11 is deformed toward the lid 20 as shown in FIG. Then, it is formed so as to come into contact with the inner surface of the lid 20 which is an exterior material.

  When the extension part 26b and the extension part 27b contact the exterior material, the positive electrode lead 26 and the negative electrode lead 27 can be short-circuited via the exterior material. As a result, it is possible to prevent a short circuit between the positive electrode active material and the negative electrode active material in a state where electric power is stored when the secondary battery 1 is collapsed. That is, the extension part 26 b and the extension part 27 b function as a short-circuit member that short-circuits the positive electrode lead 26 and the negative electrode lead 27 when an external force is applied to the exterior material or the electrode group 11.

  That is, the secondary battery 1 is disposed in the exterior material via the exterior material and the insulating layer, connected to the positive electrode lead, and extends from the positive electrode lead 26 in a direction parallel to the winding axis direction of the electrode group 11. The extending portion 26 b includes an extending portion 27 b that is connected to the negative electrode lead and extends from the negative electrode lead 27 in a direction parallel to the winding axis direction of the electrode group 11. Further, the insulating layer includes the extending portion 26b as the short-circuit member and the insulator 28 provided between the extending portion 27b and the lid 20, and the extending portion 26b, the extending portion 27b, and the lid 20. A gap 29 is provided between them. The lid 20 includes a short-circuit surface that is parallel to the winding axis direction and the thickness direction of the electrode group 11, that is, parallel to the X direction and the Y direction and faces the gap 29. When the external force is applied to the electrode group 11 and deformed, the extending portion 26 b and the extending portion 27 b are bent according to the deformation of the electrode group 11, traverse the gap 29, and contact the short-circuit surface of the lid 20. It is formed as follows.

  Furthermore, as shown in FIG. 5, if the length L of the extension part 26 b and the extension part 27 b is a length satisfying at least L> T, the extension part of the lid 20 according to the deformation of the electrode group 11. 26b and the extension part 27b can contact. Further, even when the extending portion 26b and the extending portion 27b are in contact with the lid 20 and form an angle θ with respect to the lid 20, the extending portion 26b and the extending portion 27b are long enough to satisfy the relationship of Lsin θ> T. If it is formed with a length L, the extension part 26 b and the extension part 27 b can contact the lid 20 according to the deformation of the electrode group 11.

6 and 7 show another example of a cross-sectional view when the secondary battery 1 of FIG. 2 is cut along an AA line. The same components as those shown in the examples of FIGS. 3 to 5 are denoted by the same reference numerals, and detailed description thereof is omitted.
As shown in FIG. 6, the positive electrode lead 26 includes a connecting portion 26c in addition to the lead portion 26a and the extending portion 26b, and the negative electrode lead 27 includes a connecting portion 27c in addition to the lead portion 27a and the extending portion 27b. It differs from the example of FIG. 3 thru | or FIG.

  The connecting portion 26c is a member that is connected to the lead portion 26a by displacing the extending portion 26b in a direction away from the lid 20 from the position where the positive electrode terminal 22 of the lead portion 26a is connected. The connecting portion 27c is a member that displaces the extending portion 27b in a direction away from the lid 20 from the position where the negative electrode terminal 23 of the lead portion 27a is connected to connect to the lead portion 27a.

  One end of the connecting portion 26c is connected to the lead portion 26a so as to form an angle θ with respect to a plane parallel to the lid 20 of the lead portion 26a. In addition, the extension portion 26b is connected to the other end of the connection portion 26c at an angle that cancels an angle θ formed by the lead portion 26a and one end of the connection portion 26c. That is, the extending part 26b extends from the end of the connecting part 26c by a length L in a direction parallel to the lid 20.

  One end of the connecting portion 27c is connected to the lead portion 27a so as to form an angle θ with respect to a plane parallel to the lid 20 of the lead portion 27a. Further, the extension 27b is connected to the other end of the connecting portion 27c at an angle that cancels an angle θ formed by the lead portion 27a and one end of the connecting portion 27c. That is, the extending portion 27b extends from the end portion of the connecting portion 27c by a length L in a direction parallel to the lid 20.

  The connecting portion 26c and the connecting portion 27c are bent when the electrode group 11 is deformed toward the lid 20 and a force is applied to the extending portions 26b and 26c in the Z direction as shown in FIG. It is configured as follows. The connecting portion 26c and the connecting portion 27c are formed with lower rigidity than the extending portion 26b and the extending portion 27b. For example, the connection position of the connection portion 26c with the lead portion 26a and the connection position of the connection portion 27c with the lead portion 27a are formed so as to be most easily bent. When configured in this way, when the deformed electrode group 11 comes into contact with the extension part 26b and the extension part 27b, the connection part 26c and the connection part 27c are bent in the Z direction, and the extension part 26b and The extending portion 27 b passes through the gap 29 and contacts the short-circuit surface of the lid 20. As a result, the positive electrode lead 26 and the negative electrode lead 27 can be short-circuited.

  Further, as shown in FIG. 7, the length L of the extending portion 26 b and the extending portion 27 b is such that the angle formed by the lid 20, the extending portion 26 b, and the extending portion 27 b when contacting the lid 20 is θ. It is formed with such a length. In other words, the length L of the extending portion 26b and the extending portion 27b is such that the connecting portions 26c and 27c are bent when the connecting portions 26c and 27c are bent at an angle θ from the connecting positions with the lead portions 26a and 27a, respectively. The ends of the extending portions 27b are formed so as to contact the lid 20, respectively. Also in this case, as in the example of FIGS. 3 to 5, as long as the extending portion 26 b and the extending portion 27 b, the connecting portion 26 c and the connecting portion 27 c are formed so as to satisfy the relationship of Lsin θ> T, the electrode group 11. The extension part 26 b and the extension part 27 b can come into contact with the lid 20 according to the deformation.

  Further, for example, as shown in FIG. 8, a notch 26d and a notch 27d are formed at a connection position 26e between the connection part 26c and the lead part 26a and a connection position 27e between the connection part 27c and the lead part 27a, respectively. May be. The notch 26d and the notch 27d are formed by partially cutting the members that form the positive electrode lead 26 and the negative electrode lead 27. The connection position 26e and the connection position 27e in which the notch 26d and the notch 27d are formed are more rigid than the lead part 26a and the lead part 27a, the extension part 26b and the extension part 27b, and the connection part 26c and the connection part 27c. Is formed low. Therefore, when the deformed electrode group 11 comes into contact with the extending portion 26b and the extending portion 27b, the connecting position 26e and the connecting position 27e become the extending portion 26b and the extending portion 27b, and the connecting portion 26c and the connecting portion 27c. Deform earlier. As a result, similarly to the example of FIG. 7, the connection portion 26 c and the connection portion 27 c are bent in the Z direction, and the extension portion 26 b and the extension portion 27 b pass through the gap 29 and contact the short-circuit surface of the lid 20. As a result, the positive electrode lead 26 and the negative electrode lead 27 can be short-circuited.

  The secondary battery 1 configured as described above is provided at a position in contact with the electrode group 11 when the electrode group 11 is deformed, and is connected to the lead portion 26a and the lead portion 27a of the positive electrode lead 26 and the negative electrode lead 27. Provided with a short-circuit member. When the short-circuit member is bent by the deformation of the electrode group 11 and contacts the inner surface of the lid 20, the positive electrode lead 26 and the negative electrode lead 27 are short-circuited in the exterior material. Thereby, the short circuit in the location where the positive electrode active material is provided and the location where the negative electrode active material is provided can be prevented, and a highly safe secondary battery can be provided.

  Furthermore, the secondary battery 1 configured as described above does not require a short-circuit member to be provided outside the exterior material, and the short-circuit member is formed as a part of the lead, so that assembly is facilitated. Furthermore, since the short-circuit member is not provided outside the exterior material, it is possible to prevent the positive electrode lead 26 and the negative electrode lead 27 from being short-circuited accidentally by a direct impact on the short-circuit member.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Secondary battery, 10 ... Electrode assembly, 11 ... Electrode group, 12 ... Positive electrode current collection tab, 13 ... Negative electrode current collection tab, 20 ... Lid, 22 ... Positive electrode terminal, 23 ... Negative electrode terminal, 24 ... Gasket, 26 ... positive electrode lead, 26a ... lead part, 26b ... extension part, 26c ... connection part, 27 ... negative electrode lead, 27a ... lead part, 27b ... extension part, 27c ... connection part, 28 ... insulator, 29 ... gap, 30 ... Exterior can.

Claims (6)

A bottomed rectangular tube-shaped exterior can having conductivity and a lid that is electrically conductive and disposed at an opening of the exterior can, and the exterior can and the lid are welded to form an exterior material A rechargeable battery,
A positive electrode and a negative electrode stacked through a separator are wound into a flat shape, and an electrode group accommodated in the exterior material;
A first current collecting tab projecting in a winding axis direction from one of the electrode groups;
A second current collecting tab protruding in the winding axis direction from the other of the electrode group;
A first terminal provided so as to protrude from the exterior material;
A second terminal provided so as to protrude from the exterior material;
A first lead provided in the outer can and connecting the first terminal and the first current collecting tab;
A second lead provided in the outer can and connecting the second terminal and the second current collecting tab;
A short-circuit member that short-circuits the first lead and the second lead when an external force is applied to the electrode group;
A secondary battery comprising:   The short-circuit member is disposed in the exterior material via the exterior material and an insulating layer, connected to the first lead, and extends from the first lead in a direction parallel to the winding axis direction. And a second extending member connected to the second lead and extending from the second lead in a direction parallel to the winding axis direction. 2. The secondary battery according to 1. The insulating layer has an insulator provided between the short-circuit member and the exterior material, and a gap provided between the short-circuit member and the exterior material,
When the electrode group is deformed by the external force, the first extending member and the second extending member are bent according to the deformation of the electrode group and pass through the gap to form the exterior material. The secondary battery according to claim 2, wherein the secondary battery is formed in contact with the secondary battery. The lid is parallel to the winding axis direction and the thickness direction of the electrode group, and includes a short-circuit surface facing the gap,
The said 1st extension member and the said 2nd extension member are formed according to the deformation | transformation of the said electrode group, and are formed so that it may penetrate the said space | gap and may contact the said short circuit surface. Secondary battery described in 1.   When the insulator is provided with a thickness T, and the first extension member and the second extension member are formed to extend from the insulator to the gap side with a length L, L The secondary battery according to claim 3 or 4, which has a relationship of> T. The short-circuit member is
A first connecting portion for connecting the first extending member to the first lead by displacing the first extending member in a direction away from the exterior member from the first lead;
A second connecting portion for connecting the second extending member to the second lead by displacing the second extending member in a direction away from the exterior material from the second lead;
And the angle formed by the surface extending the first extension portion, the first connection portion and the surface extending the second extension portion, and the second connection portion is θ, Lsin θ> T The secondary battery according to claim 2, wherein the relationship is a relationship.