JP6989706B2 - Rechargeable batteries and battery packs - Google Patents

Description

Embodiments of the present invention relate to secondary batteries and battery packs.

Generally, the secondary battery includes an electrode group including a positive electrode and a negative electrode, and an exterior portion for accommodating the electrode group. In some secondary batteries, the exterior portion is formed of two exterior members, and each of the two exterior members is formed of a metal such as stainless steel. In this secondary battery, the first exterior member, which is one of the exterior members, is formed in a tubular shape with a bottom having a bottom wall and a side wall, and the bottom wall and the side wall define a storage space for accommodating the electrode group. To. The storage space has an opening on the side opposite to the bottom wall. Further, in the first exterior member, a flange is formed at a portion opposite to the bottom wall, and the flange defines the opening edge of the opening of the storage space. In this secondary battery, the second exterior member is arranged to face the flange and closes the opening of the storage space. Further, the flange and the second exterior member project from the opening edge toward the outer peripheral side with respect to the side wall. A welded portion is formed in which the flange and the second exterior member are airtightly welded to the protruding portion of the flange and the second exterior member toward the outer peripheral side. Welds are formed continuously over the entire circumference of the opening. The welded portion seals the storage space to the outside.

In addition, some secondary batteries are provided with an open valve on the exterior portion. In such a secondary battery, the release valve is opened when the internal pressure of the storage space for accommodating the electrode group, that is, the internal pressure inside the exterior portion becomes a predetermined value or more. When the release valve is opened, gas is discharged from the storage space inside the exterior portion to the outside of the exterior portion via the release valve.

In a secondary battery provided with an open valve as described above, a thin portion having a thickness thinner than that of other portions of the exterior portion is formed on the open valve. Since a thin portion is formed, the open valve has low resistance to external impact. Therefore, even if the internal pressure of the storage space is smaller than a predetermined value, the release valve may be damaged by an external impact such as an impact due to physical contact. Therefore, it is required that the release valve is appropriately protected against an impact from the outside.

International Publication No. 2016/204147 Japanese Unexamined Patent Publication No. 2001-266804 Japanese Unexamined Patent Publication No. 2001-345083

An object to be solved by the present invention is to provide a secondary battery in which an open valve provided in an exterior portion is appropriately protected, and a battery pack including the secondary battery.

According to the embodiment, the secondary battery includes a first exterior member, a second exterior member, an electrode group, and an open valve. The first exterior member has a bottom wall and side walls and is made of metal. In the first exterior member, the storage space is defined by the bottom wall and the side wall, and the storage space has an opening on the side opposite to the bottom wall. The first exterior member includes a flange that projects outward from the opening edge of the opening with respect to the side wall. The electrode group includes a positive electrode and a negative electrode, and is housed in a storage space. The second exterior member is made of metal and is arranged to face the flange to close the opening of the storage space. The welded portion welds the flange and the second exterior member over the entire circumference of the opening at the protruding portion from the opening edge to the outer peripheral side to seal the storage space. The release valve is provided on the side wall of the first exterior member, and is opened when the internal pressure of the storage space becomes a predetermined value or more. The flange and the second exterior member are bent together at the bent portion provided in the protruding portion from the opening edge to the outer peripheral side. The bend is provided in the circumferential direction of the opening at least over the range where the open valve is located. By the bent portion, the extending portion from the bent portion to the outer edge of each of the flange and the second exterior member is located on the outer peripheral side with respect to the open valve.

FIG. 1 is a perspective view schematically showing a secondary battery according to the first embodiment. FIG. 2 is a perspective view schematically showing a state in which the first exterior member, the second exterior member, and the electrode group according to the first embodiment are disassembled from each other. FIG. 3 is a schematic view showing the secondary battery according to the first embodiment in a state viewed from the side where the bottom wall is located in the thickness direction. FIG. 4 is a schematic view showing a state in which the secondary battery according to the first embodiment is viewed from one side in the vertical direction. FIG. 5 is a schematic view showing a state in which the secondary battery according to the first embodiment is viewed from one side in the lateral direction. FIG. 6 is a schematic diagram illustrating the configuration of the electrode group according to the first embodiment. FIG. 7 is a schematic diagram showing an electrical connection configuration between an electrode group and one of a pair of terminals in the first embodiment. FIG. 8 shows the configuration of one of the pair of side walls along the lateral direction and the protruding portion from the side wall to the outer peripheral side in the secondary battery according to the first embodiment, vertically or substantially vertically in the horizontal direction. Moreover, it is sectional drawing which shows roughly in the cross section which passes through an open valve. FIG. 9 is a schematic view showing the configuration of the open valve and its vicinity on the inner surface of the side wall of the secondary battery according to the first embodiment. FIG. 10 is a schematic view showing a state in which a welded portion is formed in the manufacture of the secondary battery according to the first embodiment. FIG. 11 is a schematic view showing a state in which the flange and the second exterior member are cut at a position on the outer peripheral side with respect to the welded portion from the state of FIG. 10, and the outer peripheral side is trimmed from the cut position. FIG. 12 is a schematic view showing a bending line when forming a bent portion from the state of FIG. 11. FIG. 13 is a schematic view showing a secondary battery according to the first modification as viewed from the side where the bottom wall is located in the thickness direction. FIG. 14 is a schematic view showing a secondary battery according to the first modification as viewed from one side in the vertical direction. FIG. 15 is a schematic view showing the secondary battery according to the first modification as viewed from one side in the lateral direction. FIG. 16 is a perspective view schematically showing the secondary battery according to the second modification. FIG. 17 is a schematic view showing a secondary battery according to a second modification as viewed from one side in the vertical direction. FIG. 18 shows the configuration of one of the pair of side walls along the lateral direction and the protruding portion from the side wall to the outer peripheral side in the secondary battery according to the second modification, in a direction perpendicular to or substantially vertical to the lateral direction. Moreover, it is sectional drawing which shows roughly in the cross section which passes through an open valve. FIG. 19 shows the configuration of one of the pair of side walls along the lateral direction and the protruding portion from the side wall to the outer peripheral side in the secondary battery according to the third modification, in a direction perpendicular to or substantially vertical to the lateral direction. Moreover, it is sectional drawing which shows roughly in the cross section which passes through an open valve. FIG. 20 is a schematic view showing a configuration of an open valve and its vicinity on the outer surface of the side wall of the secondary battery according to the third modification. FIG. 21 is a perspective view schematically showing the secondary battery according to the fourth modification. FIG. 22 is a perspective view schematically showing a part of a battery pack including a plurality of secondary batteries according to the fourth modification. FIG. 23 is a perspective view schematically showing the secondary battery according to the fifth modification.

Hereinafter, embodiments will be described with reference to FIGS. 1 to 23.

(First Embodiment)
FIG. 1 shows a secondary battery 1 according to the first embodiment, and FIG. 2 shows a state in which the secondary battery 1 is disassembled for each member. The secondary battery 1 is, for example, a non-aqueous electrolyte battery. As shown in FIGS. 1 and 2, the secondary battery 1 includes an exterior portion 3. The exterior portion 3 is formed of a first exterior member 5 and a second exterior member 6. Each of the exterior members 5 and 6 is formed of a metal such as stainless steel. Examples of the metal other than stainless steel forming the exterior members 5 and 6 include aluminum, aluminum alloy, iron, and plated steel. The first exterior member 5 is formed in a tubular shape with a bottom. In the present embodiment, the first exterior member 5 has a bottom wall 7 and two pairs of side walls 8A, 8B, 9A, 9B, and is formed in a substantially rectangular cylinder with a bottom. In the first exterior member 5, the storage space 11 is defined by the bottom wall 7 and the side walls 8A, 8B, 9A, 9B. The electrode group 10 is stored in the storage space 11.

The storage space 11 has an opening 12 on the side opposite to the bottom wall 7. Here, in the secondary battery 1, the vertical direction (direction indicated by the arrow X1 and the arrow X2), the horizontal direction intersecting the vertical direction (the direction indicated by the arrow Y1 and the arrow Y2), and the vertical direction and the horizontal direction. It defines the thickness directions (directions indicated by arrows Z1 and Z2) that intersect with each other. In the secondary battery 1 of the present embodiment, the horizontal direction is vertical or substantially vertical to the vertical direction, and the thickness direction is vertical or substantially vertical to both the vertical direction and the horizontal direction. In the secondary battery 1, each of the pair of side walls (first side wall) 8A and 8B is extended in the vertical direction, and each of the pair of side walls (second side wall) 9A and 9B is in the horizontal direction. It will be extended along. The side walls 8A and 8B face each other and are arranged laterally apart from each other with the storage space 11 interposed therebetween. Further, the side walls 9A and 9B face each other and are arranged vertically apart from each other with the storage space 11 interposed therebetween. Further, each of the side walls 8A, 8B, 9A, and 9B extends from the bottom wall 7 toward the opening 12 along the thickness direction, and the storage space 11 is one side of the opening 12 in the thickness direction (arrow Z2). Open toward the side). The opening surface of the opening 12 is parallel to or substantially parallel to the vertical and horizontal directions of the secondary battery 1.

FIG. 3 shows the secondary battery 1 in a state viewed from the side where the bottom wall 7 is located (arrow Z1 side) in the thickness direction. Further, FIG. 4 shows the secondary battery 1 as viewed from one side in the vertical direction (arrow X2 side), and FIG. 5 shows the secondary battery 1 from one side in the horizontal direction (arrow Y1 side). Shown as seen. As shown in FIGS. 1 to 5, in the first exterior member 5, a flange 13 is provided at a portion opposite to the bottom wall 7. The flange 13 defines the opening edge 15 of the opening 12 over the entire circumference in the circumferential direction of the opening 12. Further, the flange 13 projects from the opening edge 15 toward the outer peripheral side over the entire circumference in the circumferential direction of the opening 12. Therefore, the flange 13 projects from the side walls 8A, 8B, 9A, and 9B on the side away from the opening 12 in the direction parallel to the opening surface of the opening 12.

In the present embodiment, the opening edge 15 has a pair of first opening edges 16A and 16B along the vertical direction and a pair of second opening edges 17A and 17B along the horizontal direction. The opening 12 is formed in a rectangular shape or a substantially rectangular shape. The shape of the opening 12 is not limited to a rectangular shape, and the opening 12 may be formed into, for example, a polygonal shape other than a rectangular shape, an elliptical shape, or the like.

The flange 13 has an outer edge (flange outer edge) 51. The outer edge 51 is continuous over the entire circumference in the circumferential direction of the opening 12. The outer edge 51 has a pair of first flange outer edges 52A and 52B along the vertical direction and a pair of second flange outer edges 53A and 53B along the horizontal direction. The first flange outer edge 52A forms the outer edge of the flange 13 at the protruding portion from the first opening edge 16A and the side wall 8A to the outer peripheral side, and the first flange outer edge 52B is the first opening edge 16B and the side wall. The outer edge of the flange 13 is formed at the protruding portion from 8B to the outer peripheral side. The second flange outer edge 53A forms the outer edge of the flange 13 at the protruding portion from the second opening edge 17B and the side wall 9B to the outer peripheral side, and the second flange outer edge 53B is the second opening edge 17B and the side wall. The outer edge of the flange 13 is formed at the protruding portion from 9B to the outer peripheral side.

Further, the outer edge 51 of the flange 13 has a relay outer edge (flange relay outer edge) 55A to 55D. The relay outer edge 55A is continuously extended from the first flange outer edge 52A to the second flange outer edge 53A, and the relay outer edge 55B is continuously extended from the first flange outer edge 52A to the second flange outer edge 53B. Will be done. Further, the relay outer edge 55C is continuously extended from the first flange outer edge 52B to the second flange outer edge 53A, and the relay outer edge 55D is continuously extended from the first flange outer edge 52B to the second flange outer edge 53B. It will be extended. That is, each of the relay outer edges 55A to 55D is continuously extended from the corresponding one of the pair of first flange outer edges 52A and 52B to the corresponding one of the pair of second flange outer edges 53A and 53B. Further, each of the relay outer edges 55A to 55D forms an obtuse angle at the intersection of the pair of first flange outer edges 52A and 52B with the corresponding one. Each of the relay outer edges 55A to 55D forms an obtuse angle at the intersection of the pair of second flange outer edges 53A and 53B with the corresponding one.

In the present embodiment, the second exterior member 6 is a plate-shaped member, and is formed, for example, in a substantially rectangular shape. The second exterior member 6 is arranged so as to face the flange 13, and is attached to the flange 13 from the side where the opening 12 opens. In the present embodiment, the second exterior member 6 projects from the opening edge 15 toward the outer peripheral side over the entire circumference of the opening 12 in the circumferential direction. Therefore, the second exterior member 6 projects with respect to the side walls 8A, 8B, 9A, and 9B on the side away from the opening 12 in the direction parallel to the opening surface of the opening 12. In the region on the outer peripheral side of the opening edge 15, the second exterior member 6 faces the flange 13 over the entire circumference of the opening 12 in the circumferential direction. Further, the second exterior member 6 closes the opening 12 of the storage space 11. At the portion where the second exterior member 6 closes the opening 12, the thickness direction of the plate-shaped second exterior member 6 coincides with or substantially coincides with the thickness direction of the secondary battery 1.

The plate-shaped second exterior member 6 has an outer edge (member outer edge) 61. In the present embodiment, the outer edge 61 of the second exterior member 6 forms the outer edge of the secondary battery 1 together with the outer edge 51 of the flange 13. The outer edge 61 is continuous over the entire circumference in the circumferential direction of the opening 12. The outer edge 61 has a pair of first member outer edges 62A and 62B along the vertical direction and a pair of second member outer edges 63A and 63B along the horizontal direction. The first member outer edge 62A forms the outer edge of the second exterior member 6 at the protruding portion from the first opening edge 16A and the side wall 8A to the outer peripheral side, and the first member outer edge 62B is the first opening. The outer edge of the second exterior member 6 is formed at the protruding portion from the edge 16B and the side wall 8B toward the outer peripheral side. The second member outer edge 63A forms the outer edge of the second exterior member 6 at the protruding portion from the second opening edge 17A and the side wall 9A to the outer peripheral side, and the second member outer edge 63B is the second opening. The outer edge of the second exterior member 6 is formed at the protruding portion from the edge 17B and the side wall 9B toward the outer peripheral side.

Further, the outer edge 61 of the second exterior member 6 has four relay outer edges (member relay outer edges) 65A to 65D. The relay outer edge 65A is continuously extended from the first member outer edge 62A to the second member outer edge 63A, and the relay outer edge 65B is continuously extended from the first member outer edge 62A to the second member outer edge 63B. Will be done. Further, the relay outer edge 65C is continuously extended from the first member outer edge 62B to the second member outer edge 63A, and the relay outer edge 65D is continuously extended from the first member outer edge 62B to the second member outer edge 63B. It will be extended. That is, each of the relay outer edges 65A to 65D is continuously extended from the corresponding one of the pair of first member outer edges 62A and 62B to the corresponding one of the pair of second member outer edges 63A and 63B. Further, each of the relay outer edges 65A to 65D forms an obtuse angle at the intersection of the pair of first member outer edges 62A and 62B with the corresponding one. Each of the relay outer edges 65A to 65D forms an obtuse angle at the intersection of the pair of second member outer edges 63A and 63B with the corresponding one.

In the first exterior member 5, the distance from the bottom wall 7 to the opening 12 is much smaller than the distance between the side walls 8A and 8B and the distance between the side walls 9A and 9B, respectively. Then, in the secondary battery 1, the dimension in the thickness direction is much smaller than the dimension in the vertical direction and the dimension in the horizontal direction. Further, in the present embodiment, the distance between the side walls (first side wall) 8A and 8B is larger than the distance between the side walls (second side wall) 9A and 9B, and the secondary battery 1 has a vertical direction. The dimension for is smaller than the dimension for the lateral direction. Here, the distance between the side walls 8A and 8B, that is, the distance between the first opening edges 16A and 16B corresponds to the dimension of the storage space 11 (opening 12) in the lateral direction of the secondary battery 1. The distance between the side walls 9A and 9B, that is, the distance between the second opening edges 17A and 17B corresponds to the dimension of the storage space 11 (opening 12) in the vertical direction of the secondary battery 1. The distance from the bottom wall 7 to the opening 12 corresponds to the dimension of the storage space 11 in the thickness direction of the secondary battery 1. In one embodiment, the size of the storage space 11 in the thickness direction of the secondary battery 1 is 8 mm or more and 25 mm or less. Further, in one embodiment, the dimension of the storage space 11 in the vertical direction of the secondary battery 1 is 266 mm, the dimension of the storage space 11 in the horizontal direction of the secondary battery 1 is 183 mm, and the thickness direction of the secondary battery 1 is The size of the storage space 11 is 15 mm.

In one embodiment, the distance between the side walls (first side wall) 8A and 8B is smaller than the distance between the side walls (second side wall) 9A and 9B, and the secondary battery 1 has a vertical direction. The dimension of may be larger than the dimension of the lateral direction. In another embodiment, the distance between the side walls (first side wall) 8A, 8B is the same as or substantially the same as the distance between the side walls (second side wall) 9A, 9B, in the secondary battery 1. , The dimensions in the vertical direction may be the same as or substantially the same as the dimensions in the horizontal direction. However, in each case, the distance from the bottom wall 7 to the opening 12 is much smaller than the distance between the side walls 8A and 8B and the distance between the side walls 9A and 9B, respectively. Then, in the secondary battery 1, the dimension in the thickness direction is much smaller than the dimension in the vertical direction and the dimension in the horizontal direction.

Further, in a certain embodiment, the first exterior member 5 is 0.02 mm or more in each of the bottom wall 7, the side walls 8A, 8B, 9A, 9B and the flange 13, except for the thin portion 93 of the open valve 91 described later. The wall thickness is 0.3 mm or less. The substantially plate-shaped second exterior member 6 has a wall thickness of 0.02 mm or more and 0.3 mm or less.

FIG. 6 is a diagram illustrating the configuration of the electrode group 10. As shown in FIG. 6, the electrode group 10 is formed in a flat shape, for example, and includes a positive electrode 21, a negative electrode 22, and separators 23 and 25. The positive electrode 21 includes a positive electrode current collector foil 21A as a positive electrode current collector and a positive electrode active material-containing layer 21B supported on the surface of the positive electrode current collector foil 21A. The positive electrode current collector foil 21A is an aluminum foil, an aluminum alloy foil, or the like, and has a thickness of about 10 μm to 20 μm. A slurry containing a positive electrode active material, a binder and a conductive agent is applied to the positive electrode current collector foil 21A. Examples of the positive electrode active material include, but are not limited to, oxides, sulfides, polymers, and the like that can occlude and release lithium ions. Further, from the viewpoint of obtaining a high positive electrode potential, it is preferable to use lithium manganese composite oxide, lithium nickel composite oxide, lithium cobalt composite oxide, lithium iron phosphate and the like as the positive electrode active material.

The negative electrode 22 includes a negative electrode collector foil 22A as a negative electrode current collector and a negative electrode active material-containing layer 22B supported on the surface of the negative electrode current collector foil 22A. The negative electrode current collecting foil 22A is an aluminum foil, an aluminum alloy foil, a copper foil, or the like, and has a thickness of about 10 μm to 20 μm. A slurry containing a negative electrode active material, a binder and a conductive agent is applied to the negative electrode current collector foil 22A. Examples of the negative electrode active material include, but are not limited to, metal oxides, metal sulfides, metal nitrides, carbon materials and the like that can occlude and release lithium ions. As the negative electrode active material, a substance having a lithium ion occlusion / release potential of 0.4 V or more with respect to the metallic lithium potential, that is, a lithium ion occlusion / release potential of 0.4 V (vs. ^{Li +} / Li) or more. It is preferably a substance. By using a negative electrode active material having such a lithium ion occlusion / release potential, the alloy reaction between aluminum or an aluminum alloy and lithium can be suppressed. Aluminum alloy can be used. Examples of the negative electrode active material having a lithium ion storage / release potential of 0.4 V (vs. ^{Li +} / Li) or more include lithium titanium composite oxides such as titanium oxide and lithium titanate, tungsten oxide, and amorphous tin. Examples thereof include oxides, niobium-titanium composite oxides, tin silicon oxides, silicon oxide and the like, and it is particularly preferable to use a lithium titanium composite oxide as a negative electrode active material. When a carbon material that occludes and releases lithium ions is used as the negative electrode active material, it is preferable to use a copper foil for the negative electrode current collecting foil 22A. The carbon material used as the negative electrode active material has an occlusion / release potential of lithium ions of ^{about 0 V (vs. Li +} / Li).

The aluminum alloy used for the positive electrode current collector foil 21A and the negative electrode current collector foil 22A preferably contains one or more elements selected from Mg, Ti, Zn, Mn, Fe, Cu and Si. The purity of aluminum and the aluminum alloy can be 98% by weight or more, preferably 99.99% by weight or more. Further, pure aluminum having a purity of 100% can be used as a material for a positive electrode current collector and / or a negative electrode current collector. The content of transition metals such as nickel and chromium in aluminum and aluminum alloys is preferably 100 wt ppm or less (including 0 wt ppm).

In the positive electrode current collecting foil 21A, the positive electrode current collecting tab 21D is formed by one long edge 21C and a portion in the vicinity thereof. In the present embodiment, the positive electrode current collecting tab 21D is formed over the entire length of the long side edge 21C. In the positive electrode current collector tab 21D, the positive electrode active material-containing layer 21B is not supported on the surface of the positive electrode current collector foil 21A. Further, in the negative electrode current collector foil 22A, the negative electrode current collector tab 22D is formed by one long side edge 22C and a portion in the vicinity thereof. In the present embodiment, the negative electrode current collecting tab 22D is formed over the entire length of the long side edge 22C. In the negative electrode current collector tab 22D, the negative electrode active material-containing layer 22B is not supported on the surface of the negative electrode current collector foil 22A.

Each of the separators 23 and 25 is formed of an electrically insulating material and electrically insulates between the positive electrode 21 and the negative electrode 22. Each of the separators 23 and 25 may be a sheet or the like separate from the positive electrode 21 and the negative electrode 22, or may be integrally formed with one of the positive electrode 21 and the negative electrode 22. Further, the separators 23 and 25 may be formed of an organic material, an inorganic material, or a mixture of the organic material and the inorganic material. Examples of the organic material forming the separators 23 and 25 include engineering plastics and super engineering plastics. Examples of engineering plastics include polyamide, polyacetal, polybutylene terephthalate, polyethylene terephthalate, syndiotactic polystyrene, polycarbonate, polyamideimide, polyvinyl alcohol, polyvinylidene fluoride, and modified polyphenylene ether. Examples of the superempura include polyphenylene sulfide, polyether ether ketone, liquid crystal polymer, polyvinylidene fluoride, polytetrafluoroethylene (PTFE), polyether nitrile, polysulfone, polyacrylate, polyetherimide, and thermoplastic polyimide. Be done. Examples of the inorganic material forming the separators 23 and 25 include oxides (for example, aluminum oxide, silicon dioxide, magnesium oxide, phosphor oxide, calcium oxide, iron oxide, titanium oxide) and nitrides (for example, boron nitride, etc.). (Aluminum nitride, silicon nitride, barium nitride) and the like.

In the electrode group 10, the positive electrode 21, the negative electrode 22, and the separators 23, 25 are geometrically (in a state where the separators 23 and 25 are sandwiched between the positive electrode active material-containing layer 21B and the negative electrode active material-containing layer 22B, respectively. It is wound in a flat shape around the winding axis B (virtually). At this time, for example, the positive electrode 21, the separator 23, the negative electrode 22, and the separator 25 are wound in a state of being stacked in this order. Further, in the electrode group 10, the positive electrode current collecting tab 21D of the positive electrode current collecting foil 21A projects to one side in the direction along the winding axis B with respect to the negative electrode 22 and the separators 23 and 25. Then, the negative electrode current collecting tab 22D of the negative electrode current collecting foil 22A protrudes from the positive electrode 21 and the separators 23 and 25 on the side opposite to the side on which the positive electrode current collecting tab 21D protrudes in the direction along the winding axis B. do. The electrode group 10 is arranged so that the winding shaft B is arranged along the lateral direction of the secondary battery 1, and the winding shaft B is arranged along the side walls (second side wall) 9A and 9B. In the storage space 11, the positive electrode current collector tab 21D is arranged at one end of the secondary battery 1 in the lateral direction. Then, in the storage space 11, the negative electrode current collecting tab 22D is arranged at the end of the secondary battery 1 on the side opposite to the side where the positive electrode current collecting tab 21D is located in the lateral direction.

In one embodiment, the electrode group 10 is impregnated with an electrolytic solution (not shown) in the storage space 11. As the electrolytic solution, a non-aqueous electrolytic solution is used, and for example, a non-aqueous electrolytic solution prepared by dissolving an electrolyte in an organic solvent is used. In this case, as the electrolyte to be dissolved in the organic solvent, lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium hexafluoroarsenide (LiAsF ₆₎ ), _{Lithium salts such as lithium trifluoromethanesulfonate (LiCF 3} SO ₃ ) and bistrifluoromethylsulfonylimide lithium [LiN (CF ₃ SO ₂ ) ₂ ], and mixtures thereof. Further, as the organic solvent, cyclic carbonates such as propylene carbonate (PC), ethylene carbonate (EC) and vinylene carbonate; chain carbonates such as diethyl carbonate (DEC), dimethyl carbonate (DMC) and methyl ethyl carbonate (MEC); tetrahydrofuran. Cyclic ethers such as (THF), 2-methyltetrahydrofuran (2MeTHF), and dioxolane (DOX); chain ethers such as dimethoxyethane (DME) and diethoxyethane (DEE); γ-butyrolactone (GBL), acetonitrile (AN). And sulfolan (SL) and the like. These organic solvents can be used alone or as a mixed solvent.

Further, in one embodiment, as the non-aqueous electrolyte, a gel-like non-aqueous electrolyte obtained by combining a non-aqueous electrolytic solution and a polymer material is used instead of the electrolytic solution. In this case, the above-mentioned electrolyte and organic solvent are used. Examples of the polymer material include polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyethylene oxide (PEO) and the like.

Further, in one embodiment, instead of the electrolytic solution, a solid electrolyte such as a polymer solid electrolyte and an inorganic solid electrolyte is provided as a non-aqueous electrolyte. In this case, the electrodes 23 and 25 may not be provided in the electrode group 10. Then, in the electrode group 10, instead of the separators 23 and 25, a solid electrolyte is sandwiched between the positive electrode 21 and the negative electrode 22. Therefore, in this embodiment, the solid electrolyte electrically insulates between the positive electrode 21 and the negative electrode 22.

As shown in FIGS. 1 and 2, in the first exterior member 5, the inclined surface 26A is provided on the outer surface of the side wall 8A, and the inclined surface 26B is provided on the outer surface of the side wall 8B. Each of the inclined surfaces 26A and 26B is inclined with respect to the bottom wall 7 and is inclined with respect to the thickness direction of the secondary battery 1. Then, each of the inclined surfaces 26A and 26B is inclined inward in the lateral direction of the secondary battery 1 as it is directed toward the side where the bottom wall 7 is located in the thickness direction of the secondary battery 1. In the present embodiment, the inclined surface 26A is provided on the side wall 8A at the end of the side wall 8A on the side where the bottom wall 7 is located in the thickness direction of the secondary battery 1, and is the boundary line between the side wall 8A and the bottom wall 7. Form a part. The inclined surface 26B is provided at the end of the side wall 8B on the side where the bottom wall 7 is located in the thickness direction of the secondary battery 1, and a part of the boundary line between the side wall 8B and the bottom wall 7 is provided. Form. Further, in the present embodiment, the inclined surface 26A is arranged in the central portion of the side wall 8A in the vertical direction, and the inclined surface 26B is arranged in the central portion of the side wall 8B in the vertical direction.

A pair of terminals 27A and 27B are attached to the outer surface of the first exterior member 5. One of the terminals 27A and 27B is the positive electrode terminal of the secondary battery 1, and the other of the terminals 27A and 27B is the negative electrode terminal of the secondary battery 1. In this embodiment, the terminal 27A is attached to the inclined surface 26A of the side wall 8A, and the terminal 27B is attached to the inclined surface 26B of the side wall 8B. Each of the terminals 27A and 27B is formed of a conductive material, for example, from any of aluminum, copper, stainless steel and the like.

FIG. 7 shows an electrical connection configuration between the electrode group 10 and one of the pair of terminals 27A and 27B. As shown in FIG. 7, the positive electrode current collector tab 21D of the electrode group 10 is bundled by welding such as ultrasonic welding. Then, the bundle of the positive electrode current collecting tab 21D is via one or more positive electrode leads including the positive electrode backup lead 31A, the positive electrode relay lead 32A, the positive electrode terminal lead 33A, and the like, and the corresponding one of the terminals 27A and 27B (positive electrode terminal). Is electrically connected to. At this time, the connection between the positive electrode current collecting tab 21D and the positive electrode lead, the connection between the positive electrode leads, and the connection between the positive electrode lead and the positive electrode terminal are performed by welding such as ultrasonic welding. Here, the positive electrode lead is formed of a conductive metal. Further, the positive electrode terminals (corresponding one of 27A and 27B), the positive electrode current collector tab 21D, and the positive electrode lead are electrically insulated from the exterior portion 3 (exterior members 5, 6) by an insulating member (not shown) or the like. Will be done.

Similarly, the negative electrode current collector tab 22D of the electrode group 10 is bundled by welding such as ultrasonic welding. The bundle of the negative electrode current collecting tabs 22D is interposed at one or more negative electrode leads including the negative electrode backup lead 31B, the negative electrode relay lead 32B, the negative electrode terminal lead 33B, and the like, and the corresponding one of the terminals 27A and 27B (negative electrode terminal). Is electrically connected to. At this time, the connection between the negative electrode current collecting tab 22D and the negative electrode lead, the connection between the negative electrode leads, and the connection between the negative electrode lead and the negative electrode terminal are performed by welding such as ultrasonic welding. Here, the negative electrode lead is formed of a conductive metal. Further, the negative electrode terminals (corresponding one of 27A and 27B), the negative electrode current collector tab 22D, and the negative electrode lead are electrically insulated from the exterior portion 3 (exterior members 5, 6) by an insulating member (not shown) or the like. Will be done.

FIG. 8 shows the configuration of one of the pair of side walls 9A and 9B along the lateral direction and the portion protruding from the side wall (corresponding one of 9A and 9B) to the outer peripheral side in the secondary battery 1 in the lateral direction. Shown in vertical or substantially vertical cross section. As shown in FIGS. 3 to 5, 7 and 8, the secondary battery 1 is formed with a welded portion 71 for airtightly welding the flange 13 and the second exterior member 6. The welded portion 71 is provided on the outer peripheral side of the opening edge 15 of the opening 12, that is, on the side away from the opening 12 in a direction parallel to the opening surface of the opening 12. Therefore, the welded portion 71 is provided at the protruding portion from the opening edge 15 toward the outer peripheral side in the flange 13 and the second exterior member 6. The welded portion 71 extends along the opening edge 15 and is continuously formed over the entire circumference in the circumferential direction of the opening 12. Therefore, the flange 13 and the second exterior member 6 are airtightly welded over the entire circumference in the circumferential direction of the opening 12. Since the flange 13 and the second exterior member 6 are airtightly welded at the welded portion 71 as described above, the storage space 11 is sealed and the storage space 11 is sealed.

Further, the welded portion 71 is formed between the outer edge 51 of the flange 13 and the opening edge 15, that is, between the outer edge 61 and the opening edge 15 of the second exterior member 6. In one embodiment, the outer end of the weld 71 forms the outer edge 51 of the flange 13 and the outer edge 61 of the second exterior member 6. In another embodiment, each of the flange 13 and the second exterior member 6 has some dimension from the outer edge of the weld 71 to the outer edge (51, 61). In one embodiment, the width of the welded portion 71, that is, the dimension between the inner and outer ends of the welded portion 71, is about 2 mm. The dimension from the outer end of the welded portion 71 to the outer edge 51 of the flange 13 and the outer edge 61 of the second exterior member 6 is about 8.5 mm. In the welded portion 71, the flange 13 and the second exterior member 6 are welded by, for example, resistance seam welding. By performing resistance seam welding, the cost is suppressed as compared with laser welding and the like, and the airtightness between the flange 13 and the second exterior member 6 is high.

The welded portion 71 has a pair of first welded portions 72A and 72B along the vertical direction and a pair of second welded portions 73A and 73B along the horizontal direction. The first welded portion 72A is formed in the flange 13 and the second exterior member 6 at a protruding portion from the first opening edge 16A toward the outer peripheral side. The first welded portion 72A is formed between the first flange outer edge 52A and the first opening edge 16A, that is, between the first member outer edge 62A and the first opening edge 16A. .. Further, the first welded portion 72B is formed in the flange 13 and the second exterior member 6 at a protruding portion from the first opening edge 16B toward the outer peripheral side. The first welded portion 72B is formed between the first flange outer edge 52B and the first opening edge 16B, that is, between the first member outer edge 62B and the first opening edge 16B. .. The second welded portion 73A is formed in the flange 13 and the second exterior member 6 at a protruding portion from the second opening edge 17A to the outer peripheral side. The second welded portion 73A is formed between the second flange outer edge 53A and the second opening edge 17A, that is, between the second member outer edge 63A and the second opening edge 17A. .. Further, the second welded portion 73B is formed in the flange 13 and the second exterior member 6 at a protruding portion from the second opening edge 17B toward the outer peripheral side. The second welded portion 73B is formed between the second flange outer edge 53B and the second opening edge 17B, that is, between the second member outer edge 63B and the second opening edge 17B. ..

Further, the welded portion 71 has relay welded portions 75A to 75D (see FIGS. 10 to 12 described later). The relay welded portion 75A is continuously extended from the first welded portion 72A to the second welded portion 73A, and the relay welded portion 75B is continuously extended from the first welded portion 72A to the second welded portion 73B. It will be extended. Further, the relay welded portion 75C is continuously extended from the first welded portion 72B to the second welded portion 73A, and the relay welded portion 75D is continuously extended from the first welded portion 72B to the second welded portion 73B. Will be extended. That is, each of the relay welded portions 75A to 75D is continuously extended from the corresponding one of the pair of first welded portions 72A and 72B to the corresponding one of the pair of second welded portions 73A and 73B.

The relay welded portion 75A is formed between the relay outer edge 55A of the flange 13 and the opening edge 15, that is, between the relay outer edge 65A and the opening edge 15 of the second exterior member 6. Further, the relay welded portion 75B is formed between the relay outer edge 55B of the flange 13 and the opening edge 15, that is, between the relay outer edge 65B and the opening edge 15 of the second exterior member 6. The relay welded portion 75C is formed between the relay outer edge 55C of the flange 13 and the opening edge 15, that is, between the relay outer edge 65C and the opening edge 15 of the second exterior member 6. The relay welded portion 75D is formed between the relay outer edge 55D of the flange 13 and the opening edge 15, that is, between the relay outer edge 65D of the second exterior member 6 and the opening edge 15. Each of the relay welds 75A-75D is along the corresponding one of the relay outer edges 55A-55D of the flange 13, i.e. along the corresponding one of the relay outer edges 65A-65D of the second exterior member 6. It will be extended.

Further, as shown in FIGS. 1, 2 and 8, an open valve 91 is provided on one of the pair of side walls 9A and 9B, and in the present embodiment, the open valve 91 is provided on the side wall 9B. When the internal pressure inside the exterior portion 3, that is, the internal pressure of the storage space 11 becomes a predetermined value or more, the release valve 91 is opened. When the release valve 91 is opened, gas is discharged from the storage space 11 inside the exterior portion 3 to the outside of the exterior portion 3 via the release valve 91. Note that FIG. 4 shows a state in which the secondary battery 1 is viewed from the side where the open valve 91 (side wall 9B) is located with respect to the storage space 11 in the vertical direction. Further, FIG. 8 shows a cross section passing through the release valve 91.

FIG. 9 shows the configuration of the open valve 91 and its vicinity on the inner surface of the side wall 9B. As shown in FIGS. 8 and 9, in the present embodiment, a groove 92 recessed toward the outer peripheral side is provided on the inner surface of the side wall 9B. Then, in the open valve 91, the groove 92 forms a thin portion 93 having a wall thickness thinner than that of the other portions of the side walls 8A, 8B, 9A, and 9B. In the present embodiment, the release valve 91 and the groove 92 are provided in the central portion of the side wall 9B in the lateral direction of the secondary battery 1. The groove 92 is extended linearly or substantially linearly along the lateral direction of the secondary battery 1. Further, in the cross section perpendicular to or substantially vertical in the lateral direction on the side wall 9B, the groove 92 is formed in a V shape or a substantially V shape. That is, in a cross section perpendicular to or substantially perpendicular to the extending direction of the groove 92, the groove 92 is formed in a V shape or a substantially V shape. Then, in the thin portion 93 of the release valve 91, the wall thickness of the side wall 9B becomes the thinnest at the apex of the V-shape of the groove 92. Since the thin portion 93 is formed as described above, the open valve 91 has lower resistance to impact than the other portions of the side walls 8A, 8B, 9A, and 9B.

In one embodiment, in the open valve 91, the extension dimension L1 of the groove 92 is about 50 mm. The width W1 of the groove 92 is about 0.1 mm. In the present embodiment, the extension dimension L1 of the groove 92 corresponds to the dimension of the groove 92 in the lateral direction of the secondary battery 1, and the width W1 of the groove 92 is the groove 92 in the thickness direction of the secondary battery 1. Corresponds to the dimensions of. Further, in a certain embodiment, the wall thickness t1 of the side wall 9B is about 0.1 mm at a portion other than the release valve 91, and the wall thickness t2 of the side wall 9B at the apex of the V-shape of the groove 92, that is, the thin wall portion 93. The minimum value of the wall thickness is about 0.01 mm or more and 0.02 mm or less.

Further, the secondary battery 1 is formed with a bent portion 81 in which the flange 13 and the second exterior member 6 are bent together. The bent portion 81 is provided at a protruding portion from the opening edge 15 toward the outer peripheral side in the flange 13 and the second exterior member 6. Therefore, the bent portion 81 is provided between the opening edge 15 and the outer edge 51 of the flange 13, that is, between the opening edge 15 and the outer edge 61 of the second exterior member 6. The bent portion 81 extends along the opening edge 15. Further, the bent portion 81 may be extended over a part of the circumferential direction of the opening 12, or may be continuous over the entire circumference of the opening 12. In the present embodiment, the bent portion 81 has a range in which a pair of first opening edges 16A and 16B are extended and a pair of second opening edges 17A and 17B are extended in the circumferential direction of the opening 12. It is formed over both of the areas where it is made. Therefore, the bent portion 81 is formed at least in the circumferential direction of the opening 12 over the range where the opening valve 91 is located. Further, in the present embodiment, the bent portion 81 is provided between the opening edge 15 and the welded portion 71. Therefore, in the present embodiment, the welded portion 71 is provided between the bent portion 81 and the outer edge 51 of the flange 13, that is, between the bent portion 81 and the outer edge 61 of the second exterior member 6.

Each of the flange 13 and the second exterior member 6 extends from the opening edge 15 to the bent portion 81 toward the outer peripheral side. That is, each of the flange 13 and the second exterior member 6 is extended from the opening edge 15 to the bent portion 81 on the side away from the opening 12 in the direction parallel to the opening plane. Between the opening edge 15 and the bent portion 81, each of the flange 13 and the second exterior member 6 is parallel or substantially parallel to the opening plane. Then, between the opening edge 15 and the bent portion 81, the flange 13 and the second exterior member 6 are parallel to or substantially parallel to each other.

The extending direction of each of the flange 13 and the second exterior member 6 is changed by the bent portion 81. In the present embodiment, the flange 13 and the second exterior member 6 are bent together at the bent portion 81 toward the side where the bottom wall 7 is located in the thickness direction of the secondary battery 1. Therefore, each of the flange 13 and the second exterior member 6 is extended from the bent portion 81 to the outer edge (51; 61) toward the side where the bottom wall 7 of the first exterior member 5 is located. The flange. Between the bent portion 81 and the outer edge (51; 61), each of the flange 13 and the second exterior member 6 does not bend at a portion other than the bent portion 81, that is, other than the bent portion 81. It is extended without changing the extension direction at the site. Then, between the bent portion 81 and the outer edge (51, 61), the flange 13 and the second exterior member 6 are parallel or substantially parallel to each other.

Each of the flange 13 and the second exterior member 6 bends at the bent portion 81 at any of the bending angles in the range of 30 ° or more and 150 ° or less. In one embodiment, each of the flange 13 and the second exterior member 6 bends at a bend 81 at a bend angle of 80 °. When the bending angle is within the above range, each of the flange 13 and the second exterior member 6 is oriented in a direction intersecting the opening surface of the opening 12 from the bending portion 81 to the outer edge (51; 61). It will be extended along. In this case, each of the flange 13 and the second exterior member 6 is inclined from the bent portion 81 to the outer edge (51; 61) with respect to the opening surface of the opening 12, or is perpendicular to the opening surface. It is extended along the direction. When the bending angle at the bent portion 81 is greater than 90 ° and at any angle of 150 ° or less, each of the flange 13 and the second exterior member 6 has an outer edge (from the bent portion 81). It extends toward the inner peripheral side until 51; 61). That is, each of the flange 13 and the second exterior member 6 extends from the bent portion 81 to the outer edge (51; 61) toward the side approaching the opening 12 in a direction parallel to the opening surface. In this case, the bent portion 81 forms the outer peripheral end of the protruding portion from the opening edge 15 in each of the flange 13 and the second exterior member 6.

The dimension (distance) from the opening edge 15 (side walls 8A, 8B, 9A, 9B) to the bent portion 81 is preferably as small as possible. By reducing the dimension from the opening edge 15 to the bent portion 81, it is possible to prevent the vertical dimension of the secondary battery 1 and the horizontal dimension of the secondary battery 1 from becoming large, and the energy of the secondary battery 1 is increased. The decrease in density is prevented. Further, the distance from the bent portion 81 to the outer edge 51 of the flange 13, that is, the distance from the bent portion 81 to the outer edge 61 of the second exterior member 6, is compared with the distance from the opening 12 to the bottom wall 7. Small is preferable. This prevents the size of the secondary battery 1 in the thickness direction from becoming large, and prevents the energy density of the secondary battery 1 from decreasing. In one embodiment, the dimension from the opening edge 15 to the bent portion 81 is about 0.5 mm. Then, the dimension of the storage space 11 in the thickness direction of the secondary battery 1 is about 15 mm, and the dimension from the bent portion 81 to the outer edge (51, 61) is about 12.5 mm. Then, the distance from the bent portion 81 to the inner end of the welded portion 71 is about 2 mm.

The bent portion 81 has a pair of first bent portions 82A and 82B along the vertical direction and a pair of second bent portions 83A and 83B along the horizontal direction. The first bent portion 82A is formed in the flange 13 and the second exterior member 6 at a protruding portion from the first opening edge 16A toward the outer peripheral side. The first bent portion 82A is formed between the first opening edge 16A and the first welded portion 72A. Further, the first bent portion 82B is formed in the flange 13 and the second exterior member 6 at a protruding portion from the first opening edge 16B toward the outer peripheral side. The first bent portion 82B is formed between the first opening edge 16B and the first welded portion 72B. The second bent portion 83A is formed in the flange 13 and the second exterior member 6 at a protruding portion from the second opening edge 17A toward the outer peripheral side. Then, the second bent portion 83A is formed between the second opening edge 17A and the second welded portion 73A. Further, the second bent portion 83B is formed in the flange 13 and the second exterior member 6 at a protruding portion from the second opening edge 17B to the outer peripheral side. Then, the second bent portion 83B is formed between the second opening edge 17B and the second welded portion 73B.

Each of the relay outer edges 65A-65D intersects the corresponding one of the pair of first bends 82A, 82B. At the intersection position, the angle formed by each of the relay outer edges 65A to 65D and the corresponding one of the first bent portions 82A and 82B is an acute angle. Further, each of the relay outer edges 65A to 65D intersects with the corresponding one of the pair of second bent portions 83A and 83B. At the intersection position, the angle formed by each of the relay outer edges 65A to 65D and the corresponding one of the second bent portions 83A and 83B is an acute angle.

Similarly, each of the relay welds 75A-75D intersects the corresponding one of the pair of first bends 82A, 82B. At the intersection position, the angle formed by each of the relay welded portions 75A to 75D and the corresponding one of the first bent portions 82A and 82B is an acute angle. Further, each of the relay welded portions 75A to 75D intersects with the corresponding one of the pair of second bent portions 83A and 83B. At the intersection position, the angle formed by each of the relay welded portions 75A to 75D and the corresponding one of the second bent portions 83A and 83B is an acute angle.

In the present embodiment, since the bent portion 81 is provided as described above, the extending portion from the bent portion 81 to the outer edge 51 of the flange 13 and the outer edge 61 from the bent portion 81 to the second exterior member 6 The extending portion up to is located on the outer peripheral side with respect to the side walls 8A, 8B, 9A, 9B. Further, in the protruding portion from the second opening edge 17B and the side wall 9B to the outer peripheral side, an extending portion from the second bent portion 83B to the second flange outer edge 53B of the flange 13 and the second bent portion. The extending portion from the portion 83B to the outer edge 63B of the second member of the second exterior member 6 is located on the outer peripheral side with respect to the side wall 9B and the open valve 91.

In one embodiment, to the extent that the side wall 9B extends in the circumferential direction of the opening 12, the outer edges (51; 61) of the flange 13 and the second exterior member 6 each have a bottom wall relative to the open valve 91. 7 is located on the side where it is located. In this case, in the range where the release valve 91 is located in the circumferential direction of the opening 12, the extending portion from the second bent portion 83B to the second flange outer edge 53B of the flange 13 and the second bent portion 83B. The extending portion of the second exterior member 6 from the outer peripheral side to the outer edge 63B of the second member faces the open valve 91 from the outer peripheral side. Further, in this case, in the range where the release valve 91 is located in the circumferential direction of the opening 12, the extending portion from the second bent portion 83B to the second flange outer edge 53B of the flange 13 and the second bent portion are formed. It is preferable that the extending portion from the portion 83B to the outer edge 63B of the second member of the second exterior member 6 is separated from the release valve 91 to some extent on the outer peripheral side. As a result, when the gas is discharged from the release valve 91, the path of the discharged gas is secured.

Further, in another embodiment, in the range in which the side wall 9B is extended in the circumferential direction of the opening 12, the outer edges (51; 61) of the flange 13 and the second exterior member 6 are respectively relative to the open valve 91. It is located on the side opposite to the side where the bottom wall 7 is located. However, in this case, from the viewpoint of preventing physical contact with the release valve 91, the bottom wall of each of the outer edges (51; 61) of the flange 13 and the second exterior member 6 is positioned with respect to the release valve 91. Do not leave much on the opposite side of the side. Therefore, the distance of the release valve 91 from the outer edges (51; 61) of the flange 13 and the second exterior member 6 in the thickness direction of the secondary battery 1 is very small.

Next, a method of manufacturing the secondary battery 1 of the present embodiment will be described. In the manufacture of the secondary battery 1, the first exterior member 5 and the second exterior member 6 are formed. At this time, the release valve 91 is formed on the side wall 9B of the first exterior member 5. In the present embodiment, the release valve 91 is formed by using a cylindrical roller having protrusions formed on the outer peripheral surface. In the formation of the release valve 91, the inner surface of the side wall 9B is pressurized by the protrusion of the roller. At this time, the inner surface of the side wall 9B is pressurized at the central portion of the side wall 9B in the lateral direction of the secondary battery 1. Then, the roller is rotated while the inner surface of the side wall 9B is pressurized by the protrusion of the roller. As a result, a V-shaped groove 92 recessed toward the outer peripheral side is formed on the inner surface of the side wall 9B. Then, the groove 92 forms a thin portion 93 having a wall thickness thinner than that of the other portions of the side walls 8A, 8B, 9A, and 9B. As a result, the open valve 91 including the thin portion 93 is formed on the side wall 9B.

When each of the exterior members 5 and 6 is formed, the second exterior member 6 is arranged so as to face the flange 13 of the first exterior member 5. Then, as shown in FIG. 10, the flange 13 and the second exterior member 6 are airtightly welded to form the welded portion 71. In forming the welded portion 71, first, a pair of first welded portions 72A and 72B and a pair of second welded portions 73A and 73B are formed. Then, the relay welded portions 75A to 75D are formed in a state of being inclined with respect to the first welded portions 72A and 72B and the second welded portions 73A and 73B. Here, the first welded portions 72A and 72B and the second welded portions 73A and 73B form four intersections α1 to α4. Each of the relay welds 75A to 75D is formed between the opening edge 15 and the corresponding one of the intersections α1 to α4. Therefore, each of the relay welded portions 75A to 75D is formed on the inner peripheral side (the side closer to the opening edge 15) with respect to the corresponding one of the intersection points α1 to α4.

Then, as shown in FIG. 11, the flange 13 and the second exterior member 6 are cut at a position on the outer peripheral side with respect to the welded portion 71, and the outer peripheral side is trimmed (removed) from the cut position. As a result, the outer edge 51 of the flange 13 and the outer edge 61 of the second exterior member 6 are formed. At this time, in each of the relay welded portions 75A to 75D, at a position close to the outer end or the outer end of the relay welded portion (corresponding one of 75A to 75D), the corresponding one of the relay welded portions (75A to 75D). ), The flange 13 and the second exterior member 6 are cut. Therefore, the intersections α1 to α4 formed by the first welded portions 72A and 72B and the second welded portions 73A and 73B are removed by trimming. By trimming to remove the intersection points α1 to α4, the relay outer edges 55A to 55D of the flange 13 and the relay outer edges 65A to 65D of the second exterior member 6 are formed.

Then, as shown in FIG. 12, the flange 13 and the second exterior member 6 are bent together at the bending line H1 on the inner peripheral side (the side closer to the opening 12) with respect to the first welded portion 72A. , The first bent portion 82A is formed. Similarly, by bending the flange 13 and the second exterior member 6 together on the inner peripheral side with respect to the first welded portion 72B, the first bent portion 82B is formed. Further, by bending the flange 13 and the second exterior member 6 together at the bending line H2 on the inner peripheral side (the side closer to the opening 12) with respect to the second welded portion 73A, the second bent portion is formed. 83A is formed. Similarly, by bending the flange 13 and the second exterior member 6 together on the inner peripheral side with respect to the second welded portion 73B, the second bent portion 83B is formed.

Since the relay outer edges 55A to 55D and 65A to 65D are formed as described above, the second extension portion from the first bent portion 82A to the first flange outer edge 52A and the first member outer edge 62A. Interference from the bent portions 83A and 83B to the corresponding second flange outer edge (53A; 53B) and the corresponding second member outer edge (63A; 63B) is effectively prevented. Similarly, the outer edge of the second flange corresponding to each of the second bent portions 83A and 83B of the extending portion from the first bent portion 82B to the first flange outer edge 52B and the first member outer edge 62B. Interference with the extension to (53A; 53B) and the corresponding second member outer edge (63A; 63B) is effectively prevented. As a result, in the circumferential direction of the opening 12, the bent portion extends over both the range in which the first opening edges 16A and 16B are extended and the range in which the second opening edges 17A and 17B are extended. 81 is easily formed.

Next, the operation and the like when the secondary battery 1 is used will be described. In the secondary battery 1, gas may be generated in the storage space 11 in which the electrode group 10 is housed, for example, when the battery 1 is used for a long time. When gas is generated in the storage space 11, the internal pressure of the exterior portion 3 rises. When the internal pressure of the exterior portion 3 becomes equal to or higher than a predetermined value, cracks occur in the thin portion 93 having a thinner wall thickness than the other portions in the first exterior member 5. As a result, the release valve 91 is opened, and gas is discharged from the storage space 11 inside the exterior portion 3 to the outside of the exterior portion 3 via the release valve 91. Here, a predetermined value, which is a threshold value of the internal pressure at which the release valve 91 is opened, is set lower than the internal pressure in a state where the secondary battery 1 is excessively expanded. Therefore, the release valve 91 functions as a safety mechanism for the secondary battery 1.

Here, as described above, the thin portion 93 of the release valve 91 is thinner than the other portions of the first exterior member 5. Therefore, the thin portion 93 of the release valve 91 has low resistance to an impact from the outside. In the present embodiment, in the flange 13 and the second exterior member 6, a bent portion 81 is provided at a protruding portion from the opening edge 15 toward the outer peripheral side. Then, the extending portion from the bent portion 81 to the outer edge 51 of the flange 13 and the extending portion from the bent portion 81 to the outer edge 61 of the second exterior member 6 are formed on the side walls 8A, 8B, 9A, 9B. On the other hand, it is located on the outer peripheral side. Therefore, the extending portion from the second bent portion 83B to the second flange outer edge 53B of the flange 13, and from the second bent portion 83B to the second member outer edge 63B of the second exterior member 6. The extended portion of is located on the outer peripheral side with respect to the release valve 91.

Since the configuration is as described above, in the present embodiment, when the secondary battery 1 is used or the like, the extending portion from the second bent portion 83B to the second flange outer edge 53B and the second member outer edge 63B. Therefore, physical contact with the release valve 91 from the outside is effectively prevented. Further, even if the secondary battery 1 receives an impact or the like from the outside, the parts other than the release valve 91 are physically in contact with each other, so that the stress or the like acting on the release valve 91 is reduced. Therefore, by preventing physical contact with the release valve 91 from the outside, the release valve 91 is appropriately protected against an impact from the outside. As a result, the possibility that the release valve 91 is damaged when the secondary battery 1 receives an impact from the outside is reduced.

Further, in the present embodiment, in the protruding portion of the flange 13 and the second exterior member 6 from the opening edge 15, a bent portion 81 is provided between the opening edge 15 and the welded portion 71. Then, at the bent portion 81, the flange 13 and the second exterior member 6 are bent together. Due to such a configuration, when the exterior portion 3 expands outward due to an increase in the internal pressure of the exterior portion 3, the stress due to the expansion is in the range A1 between the bent portion 81 and the welded portion 71 (see FIG. 8). ) Is distributed. Therefore, the concentration of stress on the inner end of the welded portion 71 is prevented. Since the stress is dispersed in the range A1, even if the expansion of the exterior portion 3 increases to some extent, the stress acting on the welded portion 71 or the like does not increase. Therefore, even if the internal pressure of the exterior portion 3 becomes high and the exterior portion 3 expands to some extent, the occurrence of cracks or the like in the portion other than the release valve 91 of the exterior portion 3 is effectively prevented. As a result, even if the exterior portion 3 expands to some extent, the airtightness of the exterior portion 3 of the storage space 11 in which the electrode group 10 is arranged is appropriately maintained, and the performance of the secondary battery 1 and the like are appropriately ensured. ..

Further, in the present embodiment, the flange 13 and the second exterior member 6 are bent together at the bent portion 81 toward the side where the bottom wall 7 is located. Therefore, by making the distance from the bent portion 81 to the outer edges 51 and 61 smaller than the distance from the opening 12 to the bottom wall 7, it is possible to prevent the size of the secondary battery 1 in the thickness direction from becoming large. Will be done. This prevents a decrease in the energy density of the secondary battery 1.

(Variations and applications)
In the first modification shown in FIGS. 13 to 15, only a pair of bent portions 83A and 83B along the horizontal direction are formed as the bent portion 81, and only the pair of bent portions 83A and 83B along the vertical direction are formed as the bent portions 81. ) Is not formed. That is, only the bent portions corresponding to the second bent portions 83A and 83B of the first embodiment are formed. Here, FIG. 13 shows the secondary battery 1 in a state of being viewed from the side where the bottom wall 7 is located (arrow Z1 side) in the thickness direction. Further, FIG. 14 shows the secondary battery 1 as viewed from one side in the vertical direction (arrow X2 side), and FIG. 15 shows the secondary battery 1 from one side in the horizontal direction (arrow Y1 side). Shown as seen.

Also in this modification, in each of the protruding portions from the second opening edges 17A and 17B, the flange 13 and the second exterior member 6 are formed from the opening edge 15 to the bent portion 81 (bent portion 83A or 83B). It is extended toward the outer peripheral side. Then, in each of the protruding portions from the second opening edges 17A and 17B, the extending directions of the flange 13 and the second exterior member 6 are changed by the bent portion 81 (bent portion 83A or 83B). do. For example, the flange 13 and the second exterior member 6 are bent at each of the bent portions 83A and 83B toward the side where the bottom wall 7 is located in the thickness direction of the secondary battery 1.

Further, in this modification, in each of the protruding portions from the first opening edges 16A and 16B, the flange 13 and the second exterior member 6 each have an opening 12 from the opening edge 15 to the outer edge (51; 61). It is extended toward the outer peripheral side of the. That is, the flange 13 and the second exterior member 6 have an opening 12 in a direction parallel to the opening surface without changing the extending direction from each of the first opening edges 16A and 16B to the outer edges (51 and 61). It is extended toward the side away from.

Also in this modification, the bent portion 81 (bent portion 83A, 83B) is provided between the opening edge 15 and the outer edge (51, 61), and the flange 13 and the second exterior member are provided in the bent portion 81. 6 bends together. The bent portion 81 is formed in a range in which the side walls 9A and 9B are extended in the circumferential direction of the opening 12. Therefore, also in this modification, the bent portion 81 is formed in the circumferential direction of the opening 12 at least in the range where the open valve 91 is located, as in the above-described embodiment. Therefore, in this modification as well, as in the above-described embodiment, physical contact with the release valve 91 from the outside is prevented, and the release valve 91 is appropriately protected against an impact from the outside.

The bent portion 81 may be provided at least over a range in which the release valve 91 is located in the circumferential direction of the opening 12. For example, in the configuration in which the release valve 91 is provided on the side wall 9B, the bent portion 81 may be provided at least in the circumferential direction of the opening 12 so as to extend the side wall 9B. As a result, in the range where the release valve 91 is located in the circumferential direction of the opening 12, the extending portion from the bent portion 81 to the outer edges (51, 61) of the flange 13 and the second exterior member 6 is the side wall 9B. And is located on the outer peripheral side with respect to the release valve 91.

In the second modification shown in FIGS. 16 to 18, the pair of first bent portions 82A and 82B along the vertical direction and the pair of first bent portions 82A and 82B along the vertical direction are used as the bent portions 81, as in the first embodiment described above. A pair of bent portions 83A and 83B along the lateral direction are provided. An open valve 91 is formed on the side wall 9B, and the open valve 91 is located at the center of the side wall 9B in the lateral direction of the secondary battery 1. Here, FIG. 17 shows the secondary battery 1 in a state of being viewed from one side in the vertical direction (arrow X2 side). Further, FIG. 18 shows the configuration of one of the pair of side walls 9A and 9B along the lateral direction and the portion protruding from the side wall (corresponding one of 9A and 9B) to the outer peripheral side in the secondary battery 1. A cross section perpendicular to or substantially vertical to the direction is shown, and a cross section passing through the release valve 91 is shown.

In this modification, the outer edge recess 95 is formed on the outer edge 51 of the flange 13 and the outer edge 61 of the second exterior member 6. In the outer edge recess 95, the second flange outer edge 53B and the second member outer edge 63B are recessed in the thickness direction on the side opposite to the side where the bottom wall 7 is located. Further, the outer edge recess 95 is formed over a range in which the release valve 91 is located in the circumferential direction of the opening 12. Therefore, the outer edge recess 95 is formed over a part of the range in which the side wall 9B extends in the circumferential direction of the opening 12.

By forming the outer edge recess 95, each outer edge (51; 61) of the flange 13 and the second exterior member 6 faces the open valve 91 in the range in which the release valve 91 is located in the circumferential direction of the opening 12. It is located on the side opposite to the side where the bottom wall 7 is located. Therefore, in the range where the release valve 91 is located in the circumferential direction of the opening 12, the extending portion from the second bent portion 83B to the second flange outer edge 53B, and the second bent portion 83B to the second. The extending portion up to the outer edge 63B of the member does not face the open valve 91 from the outer peripheral side. However, even within the range in which the side wall 9B is extended in the circumferential direction of the opening 12, the second flange outer edge 53B and the second member outer edge 63B are relative to the open valve 91 in the portion other than the outer edge recess 95. It is located on the side where the bottom wall 7 is located. Therefore, even within the range in which the side wall 9B is extended in the circumferential direction of the opening 12, the second flange outer edge 53B and the second member outer edge 63B are mostly in the portion deviated from the open valve 91 in the lateral direction. Is located on the side where the bottom wall 7 is located with respect to the release valve 91.

In this modification, as described above, in the range where the release valve 91 is located in the circumferential direction of the opening 12, the outer edges (51; 61) of the flange 13 and the second exterior member 6 each face the release valve 91. It is located on the side opposite to the side where the bottom wall 7 is located. As a result, the extension portion from the bent portion 81 to the outer edge (51; 61) of each of the flange 13 and the second exterior member 6 obstructs the path of the gas discharged from the open valve 91. Effectively prevented. Therefore, when the gas is discharged from the release valve 91, the path of the discharged gas is more appropriately secured.

Further, in this modification, even if the side wall 9B is extended in the circumferential direction of the opening 12, the second flange outer edge 53B and the second member outer edge 63B are formed in the portion other than the outer edge recess 95. It is located on the side where the bottom wall 7 is located with respect to the release valve 91. Therefore, even if the outer edge recess 95 is formed, physical contact with the release valve 91 from the outside is prevented as in the above-described embodiment, and the release valve 91 is appropriately subjected to an impact from the outside or the like. Be protected.

In the above-described embodiment and the like, the groove 92 of the release valve 91 is provided on the inner surface of the side wall 9B, but the groove 92 may be provided on the outer surface of the side wall 9B. Further, in the above-described embodiment or the like, the groove 92 of the release valve 91 is extended linearly or substantially linearly along the lateral direction of the secondary battery 1, but the extending direction and extending state of the groove are different. , Not limited to this. For example, in the third modification shown in FIGS. 19 and 20, a groove 92 recessed toward the inner peripheral side is provided on the outer surface of the side wall 9B. Then, the grooves 92 form two pairs of sides of the rectangle and the diagonal lines of the rectangle. Here, FIG. 19 shows the configuration of one of the pair of side walls 9A and 9B along the lateral direction and the portion protruding from the side wall (corresponding one of 9A and 9B) to the outer peripheral side in the secondary battery 1. It is shown in a cross section that is perpendicular or substantially vertical in the lateral direction, and shows a cross section that passes through the release valve 91. Further, FIG. 20 shows the configuration of the open valve 91 and its vicinity on the outer surface of the side wall 9B.

In this modification, the two pairs of sides of the rectangle formed by the groove 92 have a pair of long sides and a pair of short sides. The pair of long sides is extended along the lateral direction of the secondary battery 1, and the pair of short sides is extended along the thickness direction of the secondary battery 1. Also in this modification, in the open valve 91, the groove 92 forms a thin portion 93 having a wall thickness thinner than that of the other portions of the side walls 8A, 8B, 9A, and 9B. Further, in this modification, the release valve 91 and the groove 92 are provided in the central portion of the side wall 9B in the lateral direction of the secondary battery 1. Also in this modification, the groove 92 is formed in a V shape or a substantially V shape in a cross section perpendicular to or substantially perpendicular to the extending direction of the groove 92. Then, in the thin portion 93 of the release valve 91, the wall thickness of the side wall 9B becomes the thinnest at the apex of the V-shape of the groove 92. Since the thin-walled portion 93 is formed as described above, even in this modification, the open valve 91 has lower resistance to impact than the other portions of the side walls 8A, 8B, 9A, and 9B.

The groove 92 is formed by marking the outer surface of the side wall 9B with a punch or the like. Further, in a certain embodiment, the wall thickness t1 of the side wall 9B is about 0.1 mm at a portion other than the release valve 91, and the wall thickness t2 of the side wall 9B at the apex of the V-shape of the groove 92, that is, the thin wall portion 93. The minimum value of the wall thickness is about 0.01 mm or more and 0.02 mm or less.

Further, in the fourth modification shown in FIG. 21, in the side wall 8A, the inclined surface 26A is continuous in the vertical direction from the side wall 9A to the side wall 9B, and the inclined surface 26A extends in the vertical direction over the entire length of the side wall 8A. Will be done. Then, in the side wall 8B, the inclined surface 26B is continuous in the vertical direction from the side wall 9A to the side wall 9B, and the inclined surface 26B is extended over the entire length of the side wall 8B in the vertical direction. Also in this modification, the terminal 27A is attached to the inclined surface 26A of the side wall 8A, and the terminal 27B is attached to the inclined surface 26B of the side wall 8B. However, in this modification, the dimensions of the terminals 27A and 27B in the vertical direction of the secondary battery 1 are larger than those of the first embodiment described above.

Also in this modification, the open valve 91 is formed on the side wall 9B as in the above-described embodiment. Then, in this modification, as in the first modification, only the pair of bent portions 83A and 83B along the lateral direction are formed as the bent portions 81. Therefore, in this modification, the bent portion 81 is formed in a range in which the side walls 9A and 9B are extended in the circumferential direction of the opening 12. Therefore, also in this modification, the bent portion 81 is formed in the circumferential direction of the opening 12 at least in the range where the open valve 91 is located, as in the above-described embodiment. Therefore, in this modification as well, as in the above-described embodiment, physical contact with the release valve 91 from the outside is prevented, and the release valve 91 is appropriately protected against an impact from the outside.

In a certain modification, in the configuration in which the inclined surfaces 26A and 26B are formed as in the fourth modification, the pair of first bent portions 82A along the vertical direction is the same as in the first embodiment and the like. , 82B, and a pair of second bent portions 83A, 83B along the lateral direction may be formed as the bent portions 81.

Further, as an application example of the above-mentioned secondary battery 1, FIG. 22 shows a part of a battery pack including a plurality of secondary batteries 1 of the fourth modification. In the battery pack of this application example, the assembled battery 100 is formed from the two secondary batteries 1A and 1B. The secondary batteries 1A and 1B used in the assembled battery 100 have the same configuration as the secondary battery 1 (see FIG. 21) of the fourth modification.

In the assembled battery 100, the secondary batteries 1A and 1B are stacked along the stacking direction (directions indicated by arrows Z3 and Z4). The stacking direction of the secondary batteries 1A and 1B is the arrangement direction in which the secondary batteries 1A and 1B are arranged. Here, in the assembled battery 100, the first crossing direction (direction indicated by arrows X3 and X4) intersecting with the stacking direction, and the second crossing with respect to both the stacking direction and the first crossing direction. The crossing direction (direction indicated by the arrow Y3 and the arrow Y4) is specified. In the present embodiment, the first crossing direction is perpendicular or substantially perpendicular to the stacking direction, and the second crossing direction is perpendicular or substantially perpendicular to both the stacking direction and the first crossing direction. ..

The secondary batteries 1A and 1B are arranged next to each other in the stacking direction. Further, in the assembled battery 100 of the present application example, the secondary batteries 1A and 1B are stacked in a state where the thickness direction is parallel to or substantially parallel to the stacking direction. The secondary batteries 1A and 1B are arranged in such a state that the vertical direction is parallel or substantially parallel to the first crossing direction and the horizontal direction is parallel or substantially parallel to the second crossing direction. To. Further, in the assembled battery 100, the secondary batteries 1A and 1B are arranged in a state where the second exterior member 6 of the secondary battery 1A faces the bottom wall 7 of the secondary battery 1B. Further, in the assembled battery 100, the secondary batteries 1A and 1B are arranged in the first crossing direction with no deviation from each other or with almost no deviation from each other. Then, the secondary batteries 1A and 1B are arranged in the second crossing direction with no deviation from each other or with almost no deviation from each other.

It is preferable that an electrically insulating insulating plate (not shown) is arranged between the secondary batteries 1A and 1B. In this case, the second exterior member 6 of the secondary battery 1A faces the bottom wall 7 of the secondary battery 1B with the insulating plate interposed therebetween. Therefore, the insulating plate prevents the exterior portions 3 of the secondary batteries 1A and 1B from coming into contact with each other. Since the secondary batteries 1A and 1B are stacked as described above, the side walls (first side wall) 8A and 8B extend along the first crossing direction in each of the secondary batteries 1A and 1B of the assembled battery 100. The side walls (second side wall) 9A and 9B are provided and extend along the second crossing direction.

In this application example, the secondary batteries 1A and 1B are electrically connected by the bus bar 101 which is a connecting member. The bus bar 101 is formed of, for example, a conductive metal. The secondary batteries 1A and 1B are electrically connected in series or in parallel by the bus bar 101. In the assembled battery 100, the target terminal (first target terminal) which is one of the terminals 27A and 27B of the secondary battery 1A corresponds to the target terminal (second target terminal) which is one of the terminals 27A and 27B of the secondary battery 1B. It is connected to the target terminal) via the bus bar 101. In the application example of FIG. 22, the bus bar 101 is connected to the terminal 27B of the secondary battery 1A and is connected to the terminal 27B of the secondary battery 1B. The target terminal (27A or 27B) of the secondary battery 1A and the target terminal (27A or 27B) of the secondary battery 1B connected by the bus bar 101 are the same with respect to the center position of the assembled battery 100 in the second crossing direction. Located on the side of. That is, the target terminal (27A or 27B) of the secondary battery 1A and the target terminal (27A or 27B) of the secondary battery 1B are the same with respect to the storage space 11 of the secondary batteries 1A and 1B in the second crossing direction. Located on the side of.

In this application example, an open valve 91 is provided on the side wall 9B in each of the secondary batteries 1A and 1B. Therefore, the path of the gas discharged from the release valves 91 of the secondary batteries 1A and 1B is not obstructed by the bus bar 101. Therefore, when the gas is discharged from the release valves 91 of the secondary batteries 1A and 1B, the path of the discharged gas is more appropriately secured.

In the assembled battery 100 of the application example of FIG. 22, the secondary battery 1 of the fourth modification is used, but the present invention is not limited to this. For example, the secondary battery 1 of any of the above-described embodiments such as the secondary battery 1 of the first embodiment may be stacked in the same manner as in the application example of FIG. Also in this case, the assembled battery and the battery pack are formed from the plurality of stacked secondary batteries 1.

Further, in the fifth modification shown in FIG. 23, the open valve 91 is formed on one of the pair of side walls 8A and 8B along the vertical direction, and the open valve 91 is formed on the side wall 8A. Then, in the present modification, as in the first embodiment or the like, the bent portion 81 has a range in which the pair of first opening edges 16A and 16B are extended and a pair in the circumferential direction of the opening 12. The second opening edges 17A, 17B of the above are formed over both the extending range. Therefore, the bent portion 81 is formed at least in the circumferential direction of the opening 12 over the range where the opening valve 91 is located. Therefore, in this modification as well, as in the above-described embodiment, physical contact with the release valve 91 from the outside is prevented, and the release valve 91 is appropriately protected against an impact from the outside.

Further, in this modification, the electrode group 10 is arranged in the storage space 11 with the winding shaft B along the lateral direction of the secondary battery 1. In such a configuration, in the storage space 11, the generated gas tends to accumulate at both ends of the secondary battery 1 in the lateral direction. That is, in the storage space 11, the generated gas tends to accumulate in the region where the positive electrode current collector tab 21D is arranged and the region where the negative electrode current collector tab 22D is arranged. In this modification, since the open valve 91 is formed on the side wall 8A, gas can be easily discharged from the storage space 11 to the outside of the exterior portion 3 via the open valve 91.

As described above, the bent portion 81 may be provided at least in the circumferential direction of the opening 12 over a range in which the release valve 91 is located. For example, in the configuration in which the release valve 91 is provided on the side wall 8A, the bent portion 81 may be provided at least in the circumferential direction of the opening 12 so as to extend the side wall 8A. As a result, in the range where the release valve 91 is located in the circumferential direction of the opening 12, the extending portion from the bent portion 81 to the outer edges (51; 61) of the flange 13 and the second exterior member 6 is the side wall 8A. And is located on the outer peripheral side with respect to the release valve 91.

Further, in the above-described embodiment or the like, the welded portion 71 is formed between the bent portion 81 and the outer edges (51; 61) of the flange 13 and the second exterior member 6, but is limited to this. is not it. In one modification, the bent portion 81 is formed between the welded portion 71 and the outer edges (51; 61) of the flange 13 and the second exterior member 6. In this case, the welded portion 71 is formed between the opening edge 15 and the bent portion 81, and the welded portion 71 is located on the inner peripheral side with respect to the bent portion 81.

Further, in a certain modification, a plurality of electrode groups may be stored in the storage space 11. Further, in another modification, the second exterior member 6 is formed not in the shape of a plate but in the shape of a cylinder with a bottom similar to that of the first exterior member 5. In this case, the second exterior member 6 is also formed so as to include the bottom wall, the side wall, and the flange. Then, the flange 13 of the first exterior member 5 and the flange of the second exterior member 6 are airtightly welded at the welded portion 71. Even in the secondary battery 1 of this modification, the flange 13 and the second exterior member 6 are airtightly welded by the welded portion 71 over the entire circumference in the circumferential direction of the opening 12. The storage space 11 in which the electrode group 10 is housed is sealed with respect to the outside of the exterior portion 3.

According to the secondary battery of at least one of these embodiments or embodiments, the flange and the second exterior member are bent together at the bent portion provided in the protruding portion from the opening edge to the outer peripheral side. The bend is provided in the circumferential direction of the opening at least over the range where the open valve is located. By the bent portion, the extending portion from the bent portion to the outer edge of each of the flange and the second exterior member is located on the outer peripheral side with respect to the open valve. Therefore, it is possible to provide a secondary battery in which the release valve provided in the exterior portion is appropriately protected, and a battery pack including the secondary battery.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

Claims (14)

A first exterior member formed of metal with a bottom wall and side walls, the bottom wall and side walls define a storage space, which has an opening on the opposite side of the bottom wall. A first exterior member having a flange protruding from the opening edge of the opening toward the outer peripheral side with respect to the side wall.
A group of electrodes having a positive electrode and a negative electrode and stored in the storage space,
A second exterior member formed of metal and arranged facing the flange, the second exterior member closing the opening of the storage space.
A welded portion that seals the storage space by welding the flange and the second exterior member over the entire circumference of the opening at the protruding portion from the opening edge to the outer peripheral side.
An open valve provided on the side wall of the first exterior member and opened when the internal pressure of the storage space becomes a predetermined value or more.
The flange and the second exterior member are bent together at the protruding portion from the opening edge to the outer peripheral side, and are provided at least in the circumferential direction of the opening over the range where the opening valve is located. A bent portion that positions an extending portion from the bent portion to the outer edge of each of the flange and the second exterior member on the outer peripheral side with respect to the open valve.
A secondary battery equipped with. Each of the flange and the second exterior member extends from the opening edge toward the outer peripheral side to the bent portion.
The extending directions of the flange and the second exterior member change at the bent portion.
The secondary battery of claim 1. The secondary battery according to claim 2, wherein each of the flange and the second exterior member extends from the bent portion to the outer edge along a direction intersecting the opening surface of the opening. The secondary of claim 3, wherein each of the flange and the second exterior member extends from the bent portion to the outer edge toward the side where the bottom wall of the first exterior member is located. battery. The secondary battery according to any one of claims 1 to 4, wherein the bent portion extends along the opening edge. In the range in which the release valve is located in the circumferential direction of the opening, the outer edges of the flange and the second exterior member are each recessed on the side opposite to the side on which the bottom wall is located.
In the range in which the release valve is located in the circumferential direction of the opening, the outer edges of the flange and the second exterior member are opposite to the side where the bottom wall is located with respect to the opening valve. Located on the side,
The secondary battery according to any one of claims 1 to 5. The secondary battery according to any one of claims 1 to 6, wherein the open valve includes a thin portion whose side wall thickness is thinner than that of other portions. The secondary battery according to claim 7, wherein in the thin portion, the inner surface of the side wall is recessed toward the outer peripheral side, or the outer surface of the side wall is recessed toward the inner peripheral side. The side wall of the first exterior member is
A pair of first side walls facing each other and extending in the vertical direction, respectively.
A pair of second side walls that face each other and extend along the horizontal direction that intersects the vertical direction.
Equipped with
The secondary battery further comprises a pair of terminals, each of which is attached to one of the corresponding outer surfaces of the pair of first side walls in the first exterior member.
The secondary battery according to any one of claims 1 to 7. The open valve is provided on at least one of the pair of second side walls.
A connecting member for electrically connecting the secondary battery to the other secondary battery is connected to at least one of the pair of terminals.
The secondary battery of claim 9. The open valve is provided on at least one of the pair of first side walls.
In the electrode group, the positive electrode and the negative electrode are wound around a winding axis.
The electrode group is arranged in the storage space with the winding shaft along the pair of second side walls.
The positive electrode is provided with a positive electrode current collecting tab protruding with respect to the negative electrode on one side in the direction along the winding axis.
The negative electrode includes a negative electrode current collecting tab that protrudes with respect to the positive electrode in a direction along the winding axis opposite to the side on which the positive electrode current collecting tab protrudes.
In the storage space, the positive electrode current collecting tab is arranged at one end in the lateral direction, and the negative electrode current collecting tab is on the side opposite to the side where the positive electrode current collecting tab is located in the lateral direction. Placed on the edge,
The secondary battery of claim 9. A plurality of secondary batteries according to any one of claims 1 to 8 are provided.
The plurality of the secondary batteries include a first secondary battery and a second secondary battery that are stacked next to each other.
Each of the first secondary battery and the second secondary battery is laminated in a state where the thickness direction coincides with the stacking direction.
Battery pack. In each of the first secondary battery and the second secondary battery, the side wall of the first exterior member is
A pair of first side walls that face each other and extend along a first crossing direction that intersects the stacking direction.
A pair of second sidewalls that face each other and extend along a second crossing direction that intersects both the stacking direction and the first crossing direction.
Equipped with
Each of the first secondary battery and the second secondary battery further has a pair of terminals, each of which is attached to the corresponding outer surface of the pair of first side walls in the first exterior member. Prepare, prepare
The battery pack of claim 12. A connecting member for electrically connecting the first secondary battery and the second secondary battery is further provided.
The connecting member is connected to a first target terminal which is one of the pair of terminals of the first secondary battery, and in the pair of terminals of the second secondary battery, the first. 2 is connected to a second target terminal which is located on the same side as the first target terminal with respect to the storage space in the intersecting direction of 2.
In each of the first secondary battery and the second secondary battery, the open valve is provided on at least one of the pair of second side walls.
The battery pack of claim 13.

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