JP5925142B2 - Secondary battery - Google Patents

Description

  The present invention relates to a secondary battery used for in-vehicle use or the like.

  In recent years, lithium ion secondary batteries with high energy density have been developed as power sources for electric vehicles and the like. In an in-vehicle secondary battery, external forces such as various impacts and loads may act on an electrode group housed in a battery can. Therefore, it is necessary to prevent a short circuit in the secondary battery.

  For example, in a battery having a structure in which the electrode group and the current collecting tab and the lead are insulated from the outer can, the outermost periphery of the electrode group is insulated with an adhesive insulating tape, and faces the inner surface of the outer can in the positive electrode lead and the positive electrode current collecting tab. The portion to be covered is covered with a first insulating cover made of a resin molded product, and the portion of the negative electrode lead and the negative electrode current collector tab facing the inner surface of the outer can is covered with a second insulating cover made of a resin molded product. A technique is disclosed in which the insulating cover and the outermost insulating tape of the electrode group are fixed with a tape (Patent Document 1).

JP 2011-49066 A

  The technique described in Patent Document 1 can stably and reliably regulate the position of the insulating member when the electrode group is inserted by fixing the insulating tape and the first and second insulating covers. However, when a tape is used to fix the insulating cover, the assembly process becomes complicated and the number of parts increases, resulting in a cost increase.

  The present invention has been made in view of the above points, and an object thereof is to provide a secondary battery capable of simplifying the assembly process and improving productivity without increasing the number of parts. It is.

  In order to solve the above-described problems, the secondary battery of the present invention is configured such that the positive and negative electrodes having a mixture layer formed on one side edge of a metal foil with positive and negative electrodes formed at both ends in the winding axis direction. A pair of conductive portions formed at both ends in the winding axis direction, and a mixture layer stacking region formed between the pair of conductive portions; And a battery can that houses the electrode group, and an insulating sheet interposed between the electrode group and the battery can. The insulating sheet is thinner than the pair of first insulating sheets interposed between the pair of conductive portions and the battery can, and between the pair of first insulating sheets. A second insulating sheet extending over the mixture layer laminated region and the battery can and overlapping the first insulating sheet between the pair of conductive portions and the battery can The first insulating sheet and the second insulating sheet are joined to each other by thermal welding at least part of the overlapping portions.

  According to the present invention, it is possible to provide a secondary battery in which the assembly process is simplified and the productivity is improved without increasing the number of parts.

  Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

1 is an external perspective view of a secondary battery according to a first embodiment. The disassembled perspective view of the secondary battery of FIG. The exploded perspective view of a battery lid and a power generation element. The external appearance perspective view which shows the state which expand | deployed the winding end side of the electrode group. The perspective view which shows the heat welding of an insulating sheet. The perspective view which shows the heat welding in the multipoint of an insulating sheet. The disassembled perspective view of the insulating sheet which concerns on 2nd Embodiment. Sectional drawing of the opening part vicinity of the insulating sheet of FIG. The expansion | deployment perspective view of the insulating sheet which concerns on 3rd Embodiment.

<First Embodiment>
[Overall structure]
The case where the secondary battery of the present invention is applied to a rectangular lithium ion secondary battery will be described with reference to the drawings. FIG. 1 is an external perspective view of a secondary battery according to the present embodiment, FIG. 2 is an exploded perspective view thereof, and FIG. 3 is an exploded perspective view of a battery lid / power generation element.

  In the secondary battery 1, an electrode group 40, which is a power generation element, is housed in a thin, substantially rectangular parallelepiped battery container 2 composed of a battery lid 3 and a battery can 4. Infused and configured. The battery can 4 is formed in a flat box shape having a wide surface 4a which is a pair of wide side surfaces, a pair of narrow side surfaces and a bottom surface. The battery lid 3 and the battery can 4 are formed of a conductive metal material such as aluminum, iron, and stainless steel, for example.

  A positive electrode current collector plate 21, a negative electrode current collector plate 31, and the like are integrally assembled to the battery lid 3 to constitute a battery lid unit 10. The positive electrode current collector plate 21 and the negative electrode current collector plate 31 of the battery lid unit 10 are respectively joined to the positive electrode conductive part 40e or the negative electrode conductive part 40f of the electrode group 40 by, for example, ultrasonic welding. Thereby, the battery lid unit 10 and the electrode group 40 are combined to form a battery lid / power generation element 50. By inserting the battery lid / power generation element 50 into the battery can 4 from the opening of the battery can 4, the electrode group 40 is accommodated in the battery can 4, and finally the opening of the battery can 4 is the battery lid 3. It is supposed to be blocked by.

  When the battery lid / power generation element 50 is inserted into the battery can 4, as shown in FIG. 2, the electrode group 40 is covered with the insulating sheet 5 so as to be insulated from direct contact with the battery can 4. And accommodated in the battery can 4. The configuration of the insulating sheet 5 will be described later in detail. The battery lid 2 is sealed by joining the battery lid 3 to the battery can 4 by laser welding.

  The battery lid 3 has a liquid injection port 3a for injecting a non-aqueous electrolyte and a safety valve 13 for releasing the pressure when the internal pressure of the battery container 2 rises above a reference value due to overcharge or the like. Is provided. The liquid injection port 3a is closed by laser welding after the liquid injection stopper 11 is fitted after the injection of the electrolytic solution.

In the non-aqueous electrolyte, for example, lithium hexafluorophosphate (LiPF ₆ ) was dissolved at a concentration of 1 mol / liter in a mixed solution in which ethylene carbonate and dimethyl carbonate were mixed at a volume ratio of 1: 2. Things can be used.

  FIG. 4 is an external perspective view of the electrode group 40 in a state where the end portion on the winding end side of the electrode laminate is developed. The electrode group 40 is formed by winding an electrode laminate in which a positive electrode 41, a negative electrode 42, and first and second separators 43 and 44 are alternately stacked, around a shaft core (not shown) in a flat shape. Is a wound electrode group. The electrode group 40 includes a flat portion 40b and a pair of curved portions 40c formed continuously on both sides of the flat portion 40b. The positive electrode 41, the negative electrode 42, and the first and second separators 43 and 44 are stacked in a flat state in the flat portion 40b, and are stacked in a semi-cylindrical shape in the bending portion 40c. In a state where the electrode group 40 is accommodated in the battery can 4, the flat portion 40 b of the electrode group 40 faces the wide surface 4 a of the battery can 4.

  The positive electrode 41 has a positive electrode mixture layer 41b formed on both front and back surfaces of a positive electrode metal foil 41a made of, for example, aluminum foil. The positive electrode mixture layer 41b is applied to the positive electrode metal foil 41a, leaving an exposed portion 41c where the positive electrode metal foil 41a is exposed on one side edge. A positive electrode conductive portion bonded to the positive electrode current collector plate 21 in the electrode group 40 as shown in FIG. 3 by winding the strip-shaped exposed portion 41c where the positive electrode mixture layer 41b is not formed and the positive electrode metal foil 41a is exposed. 40e.

  The negative electrode 42 has a negative electrode mixture layer 42b formed on both front and back surfaces of a negative electrode metal foil 42a made of, for example, copper foil. The negative electrode mixture layer 42b is applied to the negative electrode metal foil 42a, leaving an exposed portion 42c where the negative electrode metal foil 42a is exposed on one side edge. The negative electrode mixture layer 42b is not formed, and the strip-shaped exposed portion 42c where the negative electrode metal foil 42a is exposed is wound, and the negative electrode bonded to the negative electrode current collector 31 in the electrode group 40 as shown in FIG. The conductive portion 40f is formed.

The positive electrode mixture layer 41b is composed of 10 parts by weight of scaly graphite as a conductive material and 10 parts by weight of polyvinylidene fluoride (binder) as a conductive material with respect to 100 parts by weight of lithium manganate (chemical formula LiMn ₂ O ₄ ) as a positive electrode active material. (Hereinafter referred to as “PVDF”), N-methylpyrrolidone (hereinafter referred to as “NMP”) is added thereto as a dispersion solvent, and kneaded. This positive electrode mixture is applied to both surfaces of an aluminum foil having a thickness of 20 μm, leaving exposed portions 41c. Thereafter, drying, pressing, and cutting are performed to obtain a positive electrode 41 having a thickness of 90 μm (total of both front and back surfaces) of the positive electrode active material application portion not including the aluminum foil.

  When forming the negative electrode mixture layer 42b, first, 10 parts by weight of PVDF as a binder is added to 100 parts by weight of amorphous carbon powder as a negative electrode active material, and NMP is added as a dispersion solvent thereto. And kneading to prepare a negative electrode mixture. The negative electrode mixture layer 42b is formed by applying this negative electrode mixture on both sides of a 10 μm thick copper foil leaving the exposed portions 42c. Thereafter, drying, pressing, and cutting are performed to obtain a negative electrode 42 having a thickness of the negative electrode active material coating portion that does not include a copper foil (total of both front and back surfaces) of 70 μm.

  In order to form the electrode group 40, the tip portions of the first and second separators 43 and 44 are welded to a shaft core (not shown), and the first and second separators 43 and 44, the positive electrode 41, and the negative electrode Wind so that 42 overlaps alternately. At this time, the winding start side end portion of the positive electrode 41 is positioned at the inner side of the wound electrode group 40 with respect to the winding start side end portion of the negative electrode 42 than the winding start side end portion of the negative electrode 42. The electrode 42 is wound around the axial center side from the winding start side end. Here, a direction parallel to the axis of the electrode group 40, that is, a direction parallel to the width direction of the exposed portions 41c and 42c is defined as a winding axis direction D. In this case, the exposed portion 41c of the positive electrode and the exposed portion 42c of the negative electrode are arranged so as to be located on the side edges of the electrode group 40 on one side and the other side in the winding axis direction D. That is, the positive and negative electrodes 41 and 42 are stacked and wound so that the exposed portions 41c and 42c are positioned at both ends in the winding axis direction D. Thus, a pair of conductive portions 40e and 40f are formed at both ends of the electrode group 40 in the winding axis direction D.

  The width of the negative electrode mixture layer 42b, that is, the length in the winding axis direction D is formed wider than the width of the positive electrode mixture layer 41b. The width of the first separator 43 is such that the exposed portion 41 c of the positive electrode 41 is exposed from the first separator 43 at one side edge of the electrode group 40. The width of the second separator 44 is set such that the exposed portion 42 c of the negative electrode 42 is exposed from the second separator 44 at the other side edge of the electrode group 40.

  A hollow portion 40a (see FIG. 4) is formed on the winding start side of the electrode group 40, in other words, on the axial core side. Further, on the winding end side of the electrode group 40, the outermost periphery is the second separator 44, and the inner side is the negative electrode 42. Accordingly, the positive electrode mixture layer 41b covers the entire length from the winding start side to the winding end side, and all the portions in the width direction are covered with the negative electrode mixture layer 42b.

  As shown in FIG. 3, the electrode group 40 is a mixture in which a positive electrode mixture layer 41 b of the positive electrode 41 and a negative electrode mixture layer 42 b of the negative electrode 42 are stacked in the center in the winding axis direction D. A layer stacked region 40d is formed. The positive electrode conductive portion 40e is disposed on one side edge of the electrode group 40 in the winding axis direction D and exposed to the outside, and the negative electrode conductive portion 40f is exposed to the other side of the electrode group 40 in the winding axis direction D. It is arranged at the edge and exposed to the outside. The positive electrode current collector plate 21 and the negative electrode current collector plate 31 connected to the positive electrode conductive part 40e and the negative electrode conductive part 40f, respectively, have the electrode group 40 accommodated in the battery can 4 and the wide surface 4a of the battery can 4 and the electrode It arrange | positions between the plane parts 40b of the group 40. FIG.

  As shown in FIG. 3, the battery lid unit 10 includes a battery lid 3, a positive electrode terminal portion 60, and a negative electrode terminal portion 70. The positive electrode terminal portion 60 includes an external positive electrode terminal 61, a positive electrode connection terminal 62, a positive electrode terminal plate 63, an insulating plate 64, and a positive electrode current collector plate 21. The external positive electrode terminal 61, the positive electrode terminal plate 63, the positive electrode connection terminal 62, and the positive electrode current collector plate 21 are fixed integrally and attached to the battery lid 3.

  The positive electrode terminal portion 60 is produced as follows. In advance, the positive electrode current collecting plate 21 is caulked to the positive electrode connection terminal 62. Then, the insulating plate 64 is disposed in the through hole of the battery cover 3 with the through hole of the battery cover 3 and the through hole of the insulating plate 64 aligned. Next, the external positive terminal 61 is fitted into a through hole provided in the positive terminal plate 63 and fixed to the positive terminal plate 63 on the insulating plate 64. The external positive terminal 61 and the positive terminal plate 63 may be caulked. Then, the positive electrode connection terminal 62 on which the positive electrode current collector plate 21 is crimped is inserted into the through hole of the insulating plate 64 from the back side of the battery lid 3. The tip end side of the positive electrode connection terminal 62 has a cylindrical shape slightly smaller than the through hole of the positive electrode terminal plate 63, and the positive electrode terminal portion 60 is attached to the battery lid by caulking the tip portion of the positive electrode connection terminal 62. 3 is integrally assembled.

  In this state, the positive electrode current collector plate 21, the positive electrode connection terminal 62, the positive electrode terminal plate 63, and the external positive electrode terminal 61 are electrically connected. Further, the positive electrode current collector plate 21, the positive electrode connection terminal 62, the positive electrode terminal plate 63, and the external positive electrode terminal 61 are insulated from the battery lid 3 by the insulating plate 64.

  The negative electrode terminal portion 70 includes an external negative electrode terminal 71, a negative electrode connection terminal 72, a negative electrode terminal plate 73, an insulating plate 74, and a negative electrode current collector plate 31. The negative electrode terminal portion 70 has the same structure as the positive electrode terminal portion 60, and the external negative electrode terminal 71, the negative electrode terminal plate 73, the negative electrode connection terminal 72, and the negative electrode current collector plate 31 are integrally fixed and attached to the battery lid 3. It has been.

  In this state, the negative electrode current collector plate 31, the negative electrode connection terminal 72, the negative electrode terminal plate 73, and the external negative electrode terminal 71 are electrically connected. Further, the negative electrode current collector plate 31, the negative electrode connection terminal 72, the negative electrode terminal plate 73, and the external negative electrode terminal 71 are insulated from the battery lid 3 by the insulating plate 74.

  The secondary battery 1 can charge and discharge external electronic devices connected to the external positive terminal 61 and the external negative terminal 71 by joining the positive and negative current collecting plates 21 and 31 to the electrode group 40. It becomes.

  The positive electrode current collector plate 21 is made of aluminum or an aluminum alloy. The positive electrode current collector plate 21 includes a flat plate-like main body portion 22 attached along the lower surface of the battery lid 3 and a pair of support portions 22a bent at approximately 90 ° downward at both ends in the width direction of the main body portion 22. Have Flat joint pieces 23 are formed at the tips of the pair of support portions 22a. Each joining piece 23 is joined to the electrode group 40 by, for example, ultrasonic welding. Each of the joining pieces 23 is bent at an angle inclined with respect to the support portion 22a. The pair of joining pieces 23 are inclined so as to be separated from each other in the short side direction of the battery lid 3 as they move from the central side in the long side direction of the battery lid 3 toward the outside, and the inclination directions are opposite to each other. Although it is a direction, it is the same angle with respect to the center plane and is line symmetric. The pair of joining pieces 23 has the positive electrode conductive portion 40e of the electrode group 40 inserted therebetween, and the positive electrode conductive portion 40e of the electrode group 40 is opened in a letter C shape, for example, by ultrasonic welding to the positive electrode conductive portion 40e. Be joined.

  The negative electrode current collecting plate 31 is formed of copper or a copper alloy, but has the same structure as the positive electrode current collecting plate 21. The negative electrode current collecting plate 31 includes a flat plate-like main body portion 32 attached along the lower surface of the battery lid 3, and a pair of support portions 32a bent downward at approximately 90 ° at both ends in the width direction of the main body portion 32. Have Flat joint pieces 33 are formed at the ends of the pair of support portions 32a. Each joining piece 33 is joined to the electrode group 40 by, for example, ultrasonic welding. Each of the joining pieces 33 is bent at an angle inclined with respect to the support portion 32a. The pair of joining pieces 33 are inclined so as to be separated from each other in the short side direction of the battery lid 3 as it moves from the central side in the long side direction of the battery lid 3 toward the outside, and the inclination directions are opposite to each other. However, it is the same angle with respect to the center plane and is line symmetric. The pair of joining pieces 33 are joined to the negative electrode conductive portion 40f by ultrasonic welding in a state where the negative electrode conductive portion 40f of the electrode group 40 is inserted between them and the negative electrode conductive portion 40f of the electrode group 40 is opened in a letter C shape. Is done.

[Insulating sheet]
Next, the configuration of the insulating sheet 5 will be described in detail.

  As shown in FIG. 2, the insulating sheet 5 is housed in the battery can 4 together with the battery lid / power generation element 50 in a state of covering the periphery of the electrode group 40, and between the electrode group 40 and the inner wall of the battery can 4. The electrode group 40 and the battery can 4 are electrically isolated from each other.

  The insulating sheet 5 is formed, for example, by bending a sheet-like insulating material into a desired shape. The insulating material used for the insulating sheet 5 is preferably a synthetic resin material that has good insulation properties, is difficult to wrinkle, and has high heat resistance. For example, polyolefin resin materials such as polypropylene and polyethylene, and polyester Polyphenylene sulfide, polyimide and the like can be preferably used.

  The insulating sheet 5 includes a pair of first insulating sheets 15 and 16 covering a pair of conductive portions 40e and 40f formed at both ends in the winding axis direction D of the electrode group 40, and the pair of first insulating sheets. And a second insulating sheet 14 extending between 15 and 16.

  The first insulating sheets 15 and 16 may be formed by bending the sheet-like insulating material described above, or may be formed by injection molding or vacuum forming the insulating material. The first insulating sheets 15 and 16 are formed, for example, to have a thickness that is rigid enough to maintain the shape independently of gravity. Moreover, it is desirable that the thickness of the first insulating sheets 15 and 16 be formed to a thickness that can prevent damage to the insulating sheet 5 due to external force, heat, or the like in a state where the secondary battery 1 is assembled. The thickness of the 1st insulating sheets 15 and 16 can be 100-300 micrometers, for example.

  The 2nd insulating sheet 14 is formed in the thickness which has a softness | flexibility or flexibility with said insulating material, for example. The thickness of the second insulating sheet 14 is preferably as thin as possible from the viewpoint of increasing the battery capacity of the secondary battery 1. The thickness of the 2nd insulating sheet 14 is thinner than the thickness of the 1st insulating sheets 15 and 16, for example, can be 20 micrometers-80 micrometers. The 1st insulating sheets 15 and 16 and the 2nd insulating sheet 14 do not need to be the same material, and can each be suitably selected from the above-mentioned insulating material.

  As shown in FIG. 2, the second insulating sheet 14 is formed by folding a single rectangular sheet member in two and covering the electrode group 40 from below the battery lid / power generation element 50. 40 is configured to cover between both ends of the winding axis direction D. The second insulating sheet 14 has a width that extends across both ends of the electrode group 40 in the winding axis direction D. Then, it extends downward from the vicinity of the lower surface of the battery cover 3, faces one surface of the flat portion 40 b of the electrode group 40, is U-turned along the lower curved portion 40 c of the electrode group 40, and It has a length that opposes the other surface of 40 b and extends to the vicinity of the lower surface of the battery lid 3. The second insulating sheet 14 includes a conductive layer 40e, 40f of the electrode group 40, current collector plates 21, 31 connected to the conductive portions 40e, 40f, and a mixture layer lamination region 40d between the conductive portions 40e, 40f. And covering.

  As shown in FIG. 2, the first insulating sheet 15 is in a state where the first insulating sheet 15 is attached to an end portion on the positive electrode side that is one side in the winding axis direction D of the electrode group 40. And a pair of side surface portions 15b, 15b facing each other with the electrode group 40 therebetween, and the cross-sectional shape thereof is a U-shape. Further, the first insulating sheet 15 has a bottom surface portion 15 c that faces the curved portion 40 c on the bottom side of the electrode group 40 between the lower end portions of the pair of side surface portions 15 b and 15 b. Note that the battery lid 3 side of the first insulating sheet 15 is opened to avoid interference with the main body portion 22 and the pair of support portions 22a of the positive electrode current collector plate 21.

  The facing surface portion 15a has a rectangular flat plate shape extending at a constant width from the curved portion 40c on the battery lid 3 side of the electrode group 40 to the curved portion 40c on the bottom side. The pair of side surface portions 15b and 15b are formed to be bent so as to face the flat surface portions 40b and 40b of the electrode group 40 on both sides in the width direction of the facing surface portion 15a. The pair of side surface portions 15b and 15b sandwich the planar portion 40b of the electrode group 40 and the second insulating sheet 14 disposed on both sides thereof. Each side surface portion 15b, 15b or support portion 22a has substantially the same width dimension as the positive electrode conductive portion 40e. With the first insulating sheet 15 attached to the electrode group 40, the outermost portion of the positive electrode conductive portion 40e is provided. Cover the outer periphery.

  The first insulating sheet 16 is a facing surface portion that faces the end surface of the electrode group 40 in a state in which the first insulating sheet 16 is attached to the end portion on the negative electrode side that is the other side in the winding axis direction D of the electrode group 40. 16a and a pair of side surface portions 16b and 16b facing each other with the electrode group 40 interposed therebetween, and the cross-sectional shape thereof is a U-shape. Furthermore, the first insulating sheet 16 has a bottom surface portion 16 c that faces the curved portion 40 c on the bottom side of the electrode group 40 between the lower ends of the pair of side surface portions 16 b and 16 b. Note that the battery lid 3 side of the first insulating sheet 16 is open to avoid interference with the main body portion 32 and the pair of support portions 32 a of the negative electrode current collector plate 31.

  The facing surface portion 16a has a rectangular flat plate shape extending at a constant width from the curved portion 40c on the battery lid 3 side to the curved portion 40c on the bottom side. The pair of side surface portions 16b and 16b are formed by being bent on both sides in the width direction of the opposing surface portion 16a, and the flat surface portion 40b or the support portion 32a of the electrode group 40 and the second insulating sheet disposed on both sides thereof. 14 is sandwiched between them. Each side surface portion 16b, 16b has substantially the same width dimension as the negative electrode conductive portion 40f, and covers the outermost periphery of the negative electrode conductive portion 40f in a state where the first insulating sheet 16 is attached to the electrode group 40.

  The first insulating sheets 15 and 16 are conductive portions 40e and 40f of the electrode group 40, current collector plates 21 and 31 connected to the conductive portions 40e and 40f, and both end portions of the second insulating sheet 14 covering these. Covering. That is, the first insulating sheets 15 and 16 overlap the second insulating sheet 14 between the conductive portions 40 e and 40 f and the inner wall of the battery can 4. Specifically, the side surface portions 15b and 16b of the first insulating sheets 15 and 16 and both end portions in the winding axis direction D of the second insulating sheet 14 are formed between the conductive portions 40e and 40f and the inner wall of the battery can 4. It overlaps between. Further, the first insulating sheets 15 and 16 overlap the second insulating sheet 14 between the current collecting plates 21 and 31 and the inner wall of the battery can 4. Specifically, the side surface portions 15b and 16b of the first insulating sheets 15 and 16 and both end portions in the winding axis direction D of the second insulating sheet 14 are connected to the current collector plates 21 and 31 and the inner wall of the battery can 4. Overlapping between.

  That is, the first insulating sheets 15 and 16 are provided between the conductive portions 40e and 40f of the electrode group 40 and the inner wall of the battery can 4 and between the current collecting plates 21 and 31 and the inner wall of the battery can 4 in the second direction. The insulating sheet 14 overlaps the outside of both end portions, that is, the inner wall side of the battery can 4. Specifically, the current collectors 21 and 31 are disposed outside the conductive portions 40e and 40f of the electrode group 40, the second insulating sheet 14 is disposed outside the conductive plates 40e and 40f, and the first insulating sheet 14 is disposed outside the current collectors. Side surfaces 15b and 16b of the sheets 15 and 16 are arranged.

  Thus, the first insulating sheets 15 and 16 and the second insulating sheet 14 are provided between the conductive portions 40e and 40f of the electrode group 40 and the inner wall of the battery can 4, and the current collecting plates 21 and 31 and the battery can. 4 is interposed between the inner wall and the inner wall. Further, the second insulating sheet 14 has a portion extending between the first insulating sheets 15 and 16 interposed between the mixture layer lamination region 40 d of the electrode group 40 and the inner wall of the battery can 4. .

  FIG. 5 is a perspective view showing thermal welding between the first insulating sheets 15 and 16 and the second insulating sheet 14. The first insulating sheets 15 and 16 and the second insulating sheet 14 are joined to each other by welding at least part of the overlapping portions. For the welding of the first insulating sheets 15 and 16 and the second insulating sheet 14, ultrasonic welding, high frequency welding, laser welding, or the like may be used. However, the material of the insulating material, the sheet thickness, and the productivity From such viewpoints, it is preferable to perform heat welding. The hot welding may be hot air welding, hot plate welding, trowel welding, or the like, but from the viewpoint of cost and productivity, impulse welding is preferable. Here, the impulse-type welding is a method of heating and welding the heated object by instantaneously generating heat in the state where the heater is pressed against the heated object and pressure is applied to the heated object. .

  In the present embodiment, the first insulating sheets 15 and 16 and the second insulating sheet 14 are overlapped with each other between the current collecting plates 21 and 31 and the battery can 4 by spot welding using impulse welding. Heat welded and joined together. Joining of the first insulating sheets 15 and 16 and the second insulating sheet 14 by heat welding is performed in the following procedure before the battery lid / power generation element 50 is accommodated in the battery can 4.

  First, as shown in FIG. 2, the second insulating sheet 14 is folded in two so as to cover the electrode group 40 from below the battery lid / power generation element 50. As a result, the conductive portions 40e and 40f, the current collector plates 21 and 31 and the mixture layer lamination region 40d of the electrode group 40 shown in FIG. 3 are covered with the second insulating sheet 14, and these outsides, that is, the battery can 4 The second insulating sheet 14 is disposed on the inner wall side of the wide surface 4a.

  Next, first insulation is provided at both ends in the winding axis direction D of the electrode group 40 so as to cover the conductive portions 40e and 40f and the current collector plates 21 and 31 of the electrode group 40 from above the second insulating sheet 14. Cover the sheets 15 and 16. As a result, the positive electrode end of the second insulating sheet 14 and the first insulating sheet are formed outside the positive electrode conductive portion 40e and the positive electrode current collector plate 21 of the electrode group 40, that is, on the inner wall side of the wide surface 4a of the battery can 4. Fifteen side surface portions 15b are arranged in this order. Further, the negative electrode side end portion of the second insulating sheet 14 and the first sheet 16 are formed outside the negative electrode conductive portion 40f of the electrode group 40 and the negative electrode current collector plate 31, that is, on the inner wall side of the wide surface 4a of the battery can 4. The side part 16b is arrange | positioned in this order. Furthermore, the opposing surface portions 15a and 16a of the first insulating sheets 15 and 16 are arranged opposite to both end surfaces of the electrode group 40 in the winding axis direction D, and both end surfaces of the electrode group 40 in the winding axis direction D are first. 1 of insulating sheets 15 and 16.

  Next, as shown in FIG. 5, the heater H is moved from the outside of the first insulating sheets 15, 16, that is, from the inner wall side of the wide surface 4 a when the electrode group 40 is accommodated in the battery can 4. Press against 15 and 16. At this time, the first sheets 15 and 16 and the second insulating sheet 14 are overlapped with each other, and the heater H is connected to the first portion at the position where the current collector plates 21 and 31 are disposed on the inner side, that is, on the electrode group 40 side. The insulating sheets 15 and 16 are pressed. Then, the inner sides of the first insulating sheets 15 and 16 and the second insulating sheet 14 stacked on each other, that is, the electrode group 40 side are supported by the current collector plates 21 and 31, and the first insulating sheets 15 and 16 The two insulating sheets 14 are sandwiched between the current collector plates 21 and 31 and the heater H to apply pressure. In this state, the heater H is instantaneously heated to join the first insulating sheets 15 and 16 and the second insulating sheet 14 together by thermal welding.

  More specifically, the side surface portion 15b of the first insulating sheet 15 and the end portion on the positive electrode side of the second insulating sheet 14 are overlapped with each other, and the positive electrode current collector plate 21 is disposed inside these, that is, on the electrode group 40 side. In the disposed portion, the heater H is pressed against the side surface portion 15b of the first insulating sheet 15. At this time, in the vicinity of the battery lid 3, the pair of support portions 22 a of the positive electrode current collector plate 21 are disposed outside, that is, sandwiched from the inner wall side of the pair of wide surfaces 4 a when the electrode group 40 is accommodated in the battery can 4, The pair of heaters H is pressed against the side surface portions 15 b of the pair of first insulating sheets 15. Then, the side part 15 b of the first insulating sheet 15 and the inner side of the end part on the positive electrode side of the second insulating sheet 14, that is, the electrode group 40 side are supported by the support part 22 a of the positive electrode current collector plate 21. As described above, the first insulating sheet 15 and the second insulating sheet 14 are sandwiched between the heater H and the support portion 22a of the positive electrode current collector plate 21 so that the first insulating sheet 15 and the second insulating sheet 14 are A pressure is applied to the insulating sheet 14. In this state, the heater H is instantaneously heated to join the first insulating sheet 15 and the second insulating sheet 14 by heat welding.

  Similarly, the side surface portion 16b of the first insulating sheet 16 and the end portion on the negative electrode side of the second insulating sheet 14 are overlapped with each other, and the negative electrode current collecting plate 31 is disposed inside them, that is, on the electrode group 40 side. The heater H is pressed against the side surface portion 16b of the first insulating sheet 16 at the portion where the first insulating sheet 16 is located. At this time, in the vicinity of the battery lid 3, the pair of support portions 32a of the negative electrode current collector plate 31 are disposed outside, that is, sandwiched from the inner wall side of the pair of wide surfaces 4a when the electrode group 40 is accommodated in the battery can 4, The pair of heaters H is pressed against the side surface portions 16 b of the pair of first insulating sheets 16. Then, the side surface portion 16 b of the first insulating sheet 16 and the inner side of the negative electrode side end portion of the second insulating sheet 14, that is, the electrode group 40 side, are supported by the support portion 32 a of the negative electrode current collector plate 31. In this manner, the first insulating sheet 16 and the second insulating sheet 14 are sandwiched between the heater H and the support portion 32a of the negative electrode current collector plate 31, thereby the first insulating sheet 16 and the second insulating sheet 16 are held. A pressure is applied to the insulating sheet 14. In this state, the heater H is instantaneously heated, and the first insulating sheet 16 and the second insulating sheet 14 are joined by thermal welding. The pair of first insulating sheets 15 and 16 and the second insulating sheet 14 can be welded simultaneously.

  As described above, each of the pair of first insulating sheets 15 and 16 includes the side surface portions 15b and 16b facing the one wide surface 4a of the battery can 4 and the side surface portions 15b and 16b facing the other wide surface 4a. However, in the vicinity of the battery lid 3, each one point is joined to the second insulating sheet 14. Thus, the battery lid / power generation element 50 is in a state in which the electrode group 40 is wrapped by the insulating sheet 5 except for the battery lid 3 side, and the insulating sheet 5 is attached to the electrode group 40. Thereafter, the battery lid / power generation element 50 is accommodated in the battery can 4. Accordingly, the insulating sheet 5 is interposed between the conductive portions 40 e and 40 f of the electrode group 40 and the battery can 4 and between the current collector plates 21 and 31 and the battery can 4. Thereafter, the opening of the battery can 4 is sealed with the battery lid 3, the nonaqueous electrolyte is injected into the battery container 2 through the injection port 3 a, and the injection port 3 a is closed with the injection plug 11. The secondary battery 1 is completed.

  Next, the effect | action of the secondary battery 1 of this embodiment is demonstrated.

  As described above, the secondary battery 1 of the present embodiment includes the pair of first insulating sheets 15 and 16 interposed between the pair of conductive portions 40e and 40f of the electrode group 40 and the battery can 4, and the first A second insulating sheet 14 that is thinner than the first insulating sheets 15 and 16 and extends between the first insulating sheets 15 and 16. The second insulating sheet 14 is interposed between the mixture layer laminated region 40 d and the battery can 4, and between the pair of conductive portions 40 e and 40 f and the battery can 4, overlapping. And the 1st insulating sheets 15 and 16 and the 2nd insulating sheet 14 are mutually joined by at least one part of the part which mutually overlaps by heat welding.

  Therefore, compared to the case where the first insulating sheets 15 and 16 and the second insulating sheet 14 are joined using a joining member such as a tape, the number of parts does not increase, workability is good, and production Improves. Further, the first insulating sheets 15 and 16 having a relatively thick sheet thickness are interposed between the pair of conductive portions 40 e and 40 f and the battery can 4. Therefore, the insulation between the conductive portions 40e and 40f and the battery can 4 can be improved. In addition, the second insulating sheet 14 overlaps the first insulating sheets 15 and 16 between the conductive portions 40e and 40f and the battery can 4, so that the conductive portions 40e and 40f and the battery can 4 are connected to each other. The insulating sheets 15 and 16 and the second insulating sheet 14 are double insulated. Therefore, the insulation between the conductive portions 40e and 40f and the battery can 4 can be further improved.

  The second insulating sheet 14 is thinner than the first insulating sheets 15 and 16 and extends between the first insulating sheets 15 and 16. In the portion between the first insulating sheets 15 and 16 of the electrode group 40, that is, the portion between the conductive portions 40e and 40f, the mixture layers 41b and 42b of the electrodes 41 and 42 constituting the electrode group 40 are laminated. This is the mixture layer lamination region 40d. Therefore, as described above, the thickness of the second insulating sheet 14 is made as thin as possible, for example, 20 μm to 80 μm. In this way, by reducing the thickness of the second insulating sheet 14 covering the mixture layer lamination region 40d as much as possible, the total thickness of the mixture layer lamination region 40d of the electrode group 40 and the number of turns of the electrode laminate can be increased. it can. Therefore, the battery capacity of the secondary battery 1 can be increased and the volume energy density can be increased. Moreover, the clearance between the battery can 4 can be increased by reducing the thickness of the second insulating sheet 14. Therefore, it is possible to prevent the battery can 4 from bulging due to the expansion and contraction of the mixture layer stacking region 40d due to the charging and discharging of the secondary battery 1. In addition, by placing the thin second insulating sheet 14 between the mixture layer stacking region 40 d of the electrode group 40 and the battery can 4, the separator 44 is damaged when the electrode group 40 is inserted into the battery can 4. Can be inserted smoothly.

  However, when the thickness of the second insulating sheet 14 is smaller than 20 μm or when the second insulating sheet 14 is not installed, the separator 44 disposed on the outermost periphery of the electrode group 40 is easily damaged. That is, since the separator 44 is a porous, thin and soft resin film, when the electrode group 40 is inserted into the battery can 4, the separator 44 may be broken or scratched, leading to problems such as an internal short circuit. There is sex. Further, when the second insulating sheet 14 is not installed, a large sliding friction between the separator 44 and the battery can 4 also causes the separator 44 to be broken and causes a decrease in productivity. Therefore, the second insulating sheet 14 is necessary and preferably has a thickness of, for example, 20 μm or more.

  Further, since the second insulating sheet 14 is thinner than the first insulating sheets 15 and 16, the flexibility or flexibility of the second insulating sheet 14 is higher than that of the first insulating sheets 15 and 16. can do. Therefore, as described above, the electrode group 40 can be entirely covered by bending the second insulating sheet 14 in half, and the operation is facilitated. Further, by covering the electrode group 40 with the second insulating sheet 14 in this way, the bent portion of the second insulating sheet 14 comes into contact with the curved portion 40c of the electrode group 40 located on the bottom surface side of the battery can 4. The displacement of the second insulating sheet 14 is prevented by the frictional resistance between them.

  Further, since the first insulating sheets 15 and 16 are thicker than the second insulating sheet 14, the rigidity of the first insulating sheets 15 and 16 can be made higher than that of the second insulating sheet 14. Therefore, as described above, the shapes of the first insulating sheets 15 and 16 are formed in advance so as to cover the conductive portions 40e and 40f of the electrode group 40 and the both end surfaces of the electrode group 40 in the winding axis direction D. be able to. By forming the first insulating sheets 15 and 16 in this manner in advance, the first insulating sheets 15 and 16 are simply covered on both ends of the electrode group 40 in the winding axis direction D. The both end surfaces of the conductive parts 40e and 40f and the electrode group 40 in the winding axis direction D can be covered. Therefore, the process of interposing the first insulating sheets 15 and 16 between the conductive portions 40e and 40f and the battery can 4 is facilitated.

  Further, the first insulating sheets 15 and 16 formed in advance can be covered on the second insulating sheet 14 covering the electrode group 40 so as to be bent in half as described above. Thereby, the first insulating sheets 15 and 16 and the second insulating sheet 14 overlap on the conductive portions 40e and 40f of the electrode group 40, and the pair of side surface portions 15b and 15b of the first insulating sheet 15 on the positive electrode side overlap. In the middle, the end of the second insulating sheet 14 on the positive electrode side is sandwiched. In addition, the end portion on the negative electrode side of the second insulating sheet 14 is sandwiched between the pair of side surface portions 16 b and 16 b of the first insulating sheet 16 on the negative electrode side. Thus, the both ends of the second insulating sheet 14 bent in half in the winding axis direction D are sandwiched between the first sheets 15 and 16, thereby preventing the opening of the second insulating sheet 14. The shape of the insulating sheet 5 is maintained. In this state, by joining the first insulating sheets 15 and 16 and the second insulating sheet 14 by heat welding, workability is improved and productivity is improved.

  In addition, the first insulating sheet 15 is covered with the first insulating sheets 15 and 16 formed in advance on the second insulating sheet 14 that covers the electrode group 40 so as to be bent in half as described above. 16 are stacked on the outside of the second insulating sheet, that is, on the battery can 4 side. Therefore, when the first insulating sheets 15 and 16 and the second insulating sheet 14 are joined by heat welding, the heater H can be pressed against the relatively thick first insulating sheets 15 and 16. Therefore, it is possible to prevent the relatively thin second insulating sheet 14 from coming into contact with the heater H and being damaged. Further, the relatively thin second insulating sheet 14 is indirectly heated by the heater H via the relatively thick first insulating sheets 15 and 16. Therefore, it is possible to prevent the second insulating sheet 14 from being damaged due to heat and causing poor welding.

  Further, by joining the first insulating sheets 15 and 16 and the second insulating sheet 14 by thermal welding, when the battery lid / power generation element 50 is inserted into the battery can 4, the first insulating sheet 15, 16 and the second insulating sheet 14 are bonded to the first electrode group 40. The displacement of the insulating sheets 15 and 16 is prevented. Therefore, the first insulating sheets 15 and 16 are prevented from being sandwiched between the battery lid 3 and the battery can 4, and poor welding is performed when the battery lid 3 and the battery can 4 are sealed by laser welding. Can be prevented.

  The first insulating sheets 15 and 16 and the second insulating sheet 14 are joined to each other by heat welding between the current collector plates 21 and 31 and the battery can 4. Therefore, the inside of the first insulating sheets 15 and 16 and the second insulating sheet 14, that is, the electrode group 40 side can be supported by the support portions 22 a and 32 a of the current collector plates 21 and 31. As a result, the first insulating sheets 15 and 16 and the second insulating sheet 14 are sandwiched between the support portions 22a and 32a of the current collector plates 21 and 31 and the heater H and welded in a state where pressure is applied. can do. Therefore, it is possible to prevent welding failure between the first insulating sheets 15 and 16 and the second insulating sheet 14 and to bond them reliably.

  In the present embodiment, the first insulating sheets 15 and 16 are made as thick as possible, for example, 100 to 300 μm. The first insulating sheets 15 and 16 are formed in the state where the secondary battery 1 is assembled, the portions interposed between the conductive portions 40e and 40f of the electrode group 40 and the battery can 4 and the current collecting plates 21 and 31. And a portion interposed between the battery can 4 and the battery can 4. Therefore, when an external force is applied to the battery can 4 or the terminal portions 60 and 70, the first insulating sheets 15 and 16 are sandwiched between the current collector plates 21 and 31 and the battery can 4, and strong against them. There is a possibility of pushing. Further, when the electrode group 40 is inserted into the battery can 4 together with the insulating sheet 5, the current collector plates 21, 31 come into contact with the battery can 4 via the first insulating sheets 15, 16, and the first insulating sheet 15 , 16 may rub against the current collector plates 21, 31 and the battery can 4. Furthermore, when a large current flows through the current collecting plates 21 and 31, the current collecting plates 21 and 31 may become high temperature. However, in this embodiment, since the first insulating sheets 15 and 16 are made as thick as possible as described above, the strength of the first insulating sheets 15 and 16 can be improved and damage can be prevented. Therefore, it is possible to withstand the external force and high temperature as described above and maintain insulation between the conductive portions 40e and 40f of the electrode group 40 and the battery can 4 or between the current collector plates 21 and 31 and the battery can 4. it can.

  Moreover, each of the 1st insulating sheets 15 and 16 and the 2nd insulating sheet 14 are joined by spot welding. Therefore, as shown in FIG. 2, before the battery lid / power generation element 50 is inserted into the battery can 4, the electrode group 40 is covered with the second insulating sheet 14, and the first insulating sheets 15, 16 are further formed thereon. As shown in FIG. 5, the heater H is pressed against a portion where the first insulating sheets 15 and 16 and the second insulating sheet 14 overlap, and the first insulating sheets 15 and 16 and the second insulating sheet 14 The two insulating sheets 14 can be easily and instantaneously joined. Therefore, the manufacturing process of the secondary battery 1 can be simplified and productivity can be improved.

  In addition, each of the first insulating sheets 15 and 16 has a portion facing the one wide surface 4a of the battery can 4 and a portion facing the other wide surface 4a, one point each for the second insulating sheet 14 and It is joined. Thereby, the 1st insulating sheets 15 and 16 and the 2nd insulating sheet 14 are joined in the part which pinches | interposes the electrode group 40 from both sides. Therefore, when the electrode group 40 whose periphery is covered with the insulating sheet 5 is inserted into the battery can 4, the insulating sheet 5 is difficult to be separated into the first insulating sheets 15 and 16 and the second insulating sheet 14. Workability is improved. Moreover, productivity can be improved by minimizing the welding point between the first insulating sheets 15 and 16 and the second insulating sheet 14. Further, the bottom surface portions 15c and 16c of the first insulating sheets 15 and 16 can be kept in close contact with the second insulating sheet 14 so that frictional force can be applied to each other, and insulation can be achieved while minimizing the welding point. It is possible to make it difficult for the sheet 5 to be separated into the first insulating sheets 15 and 16 and the second insulating sheet 14.

  Moreover, in this embodiment, the 1st insulating sheets 15 and 16 and the 2nd insulating sheet 14 are joined by spot welding in the vicinity of the battery cover 3, ie, the opening part of the battery can 4. FIG. Therefore, it is possible to reliably prevent the first insulating sheets 15 and 16 and the second insulating sheet 14 from separating after the electrode group 40 starts to be inserted into the battery can 4 until the insertion is completed.

  In addition, it is difficult not only to integrally manufacture insulating sheets having different thicknesses by injection molding, but also when the insulating sheets are covered with the electrode group 40, the rigidity is partially different. Therefore, workability deteriorates and productivity decreases. However, the insulating sheet 5 of the present embodiment is composed of the first insulating sheets 15 and 16 and the second insulating sheet 14 which are separate members. Therefore, it becomes easy to manufacture each of the first insulating sheets 15 and 16 and the second insulating sheet 14 to an optimum thickness.

  As described above, according to the present embodiment, a part of the first insulating sheets 15 and 16 and the second insulating sheet 14 having different thicknesses are integrally welded at a position where they overlap each other by heat welding. Thus, the electrode group 40 can be reliably wrapped. Furthermore, when the electrode group 40 is inserted into the battery can 4, the insulation sheet 5 is prevented from being displaced, and the secondary battery 1 can be easily assembled and the productivity is improved. Moreover, according to the secondary battery 1 having the above configuration, the insulation between the electrode group 40 and the battery can 4 against external force can be enhanced without reducing the battery capacity.

  In the above description, the first insulating sheets 15 and 16 and the second insulating sheet 14 are joined by thermal welding at one point on both sides in the thickness direction of the electrode group 40 in the vicinity of the battery lid 3. Bonding by heat welding may be performed at multiple points on both sides of the electrode group 40 in the thickness direction. This case will be described with reference to FIG.

  FIG. 6 is a perspective view showing thermal welding at multiple points of the insulating sheet. As shown in FIG. 6, on both sides in the thickness direction of the electrode group 40, it is possible to perform heat welding not only in the vicinity of the battery lid 3, but also at a plurality of welding points P in the height direction of the electrode group 40. The electrode group 40 can be securely and firmly wrapped. The heat welding at the plurality of welding points P in the height direction may be performed sequentially by impulse welding using the heater H as shown in FIG. May be.

Second Embodiment
Next, a second embodiment of the present invention will be described with reference to FIGS.

  FIG. 7 is an exploded perspective view of the insulating sheet according to the second embodiment. FIG. 8 is a cross-sectional view of the vicinity of the opening 15 d of the first insulating sheet 15 on a plane parallel to the battery lid 3.

  The secondary battery of the present embodiment is different from the secondary battery 1 described in the first embodiment described above in the configuration of the battery lid / power generation element and the insulating sheet. Since other configurations are the same as those of the secondary battery of the first embodiment, the same parts are denoted by the same reference numerals and description thereof is omitted.

  The battery lid / power generation element 150 of the present embodiment is different from the battery lid / power generation element 50 of the first embodiment only in the configuration of the positive electrode current collector plate 121 and the negative electrode current collector plate 131. The positive electrode current collector plate 121 is attached to the lower surface of the battery lid 3 and has a flat plate-like main body portion 122. The positive electrode current collecting plate 121 is bent downward at approximately 90 ° at one end in the width direction of the main body portion 122 and is connected to the battery can 4 It has the support part 122a facing one wide surface 4a. A flat joining piece 123 is formed at the tip of the support portion 122a. The joining piece 123 is in contact with one side of the pair of flat surface portions 40b of the electrode group 40 and joined to the positive electrode conducting portion 40e by, for example, ultrasonic welding in a state in which a contact plate is provided on the opposite side, whereby the positive conducting portion 40e. It is fixed and electrically connected. Further, the negative electrode current collector 131 of the present embodiment is also provided on the negative electrode side of the electrode group 40 with the same structure as the positive electrode current collector 121.

  The insulating sheet 105 of the present embodiment is different from the insulating sheet 5 of the first embodiment only in that the openings 15d and 16d are formed in the opposing surface portions 15a and 16a of the pair of first insulating sheets 15 and 16, respectively. Is different. Accordingly, each of the first insulating sheets 15 and 16 and the second insulating sheet 14 are joined one by one on both sides in the thickness direction of the electrode group 40 in the vicinity of the battery lid 3 by thermal welding. That is, on the side of the electrode group 40 where the current collecting plates 121 and 131 are provided, each of the first insulating sheets 15 and 16 and the second insulating sheet 14 are arranged on the current collecting plates 121 and 131. One point of the overlapping portion is joined to each other by spot welding. Also, on the side of the electrode group 40 where the current collector plates 121 and 131 are not provided, each of the first insulating sheets 15 and 16 and the second insulating sheet 14 is spot-welded at one point where they overlap. Are joined together. In other words, each of the first insulating sheets 15 and 16 and the second insulating sheet 14 are positioned between one wide surface 4a of the battery can 4 and the current collecting plates 121 and 131, and One welding point P is provided at each position facing the other wide surface 4a on the opposite side.

  The openings 15d and 16d are provided in the facing surface portions 15a and 16a of the first insulating sheets 15 and 16 that face the end surface of the electrode group 40 in the winding axis direction D. As shown in FIG. 8, when the first insulating sheet 15 and the second insulating sheet 14 are joined to each other by thermal welding, the opening 15d is formed between the first insulating sheet 15 and the second insulating sheet 14 and The support member 80 arranged between the electrode group 40 is opened at a position and shape into which the support member 80 can be inserted. Similarly, when the first insulating sheet 16 and the second insulating sheet 14 are bonded to each other by heat welding, the opening 16d is formed by the first insulating sheet 16, the second insulating sheet 14, and the electrode group 40. It is opened at a position and shape into which the support member 80 disposed between them can be inserted.

  When the support member 80 joins the first insulating sheets 15 and 16 and the second insulating sheet 14 at the welding point P, the first insulating sheets 15 and 16 and the second insulating sheet 14 are connected to the electrode group 40 side. It is a member for supporting from. The above-described heater H (thermal welding chip) is joined at the welding point P with the first insulating sheets 15 and 16 and the second insulating sheet 14 sandwiched between the support member 80. The support member 80 is not particularly limited as long as the support member 80 has, for example, an elongated plate shape and has a strength that does not bend even when the heater H is pressed with a predetermined pressure. As a material of the support member 80, for example, metal, hard plastic, ceramic, laminated plate, or the like can be used.

  As shown in FIG. 8, the openings 15 d and 16 d are formed in the direction perpendicular to the wide surface 4 a of the battery can 4, that is, in the direction perpendicular to the plane part 40 b of the electrode group 40 and the second insulating sheet 14. Is opened at a position communicating with the. The openings 15 d and 16 d are opened with an opening width necessary for a height including at least the same height as the welding point P in the height direction of the battery can 4 perpendicular to the bottom surface of the battery can 4. That is, the openings 15d and 16d are formed such that when the support member 80 is inserted from the openings 15d and 16d in the winding axis direction D, the support member 80 is connected to the first insulating sheets 15 and 16 and the second insulating sheet 14. It is opened so that it can arrange | position between the welding point P of this, and the electrode group 40. FIG.

  The openings 15d and 16d are usually provided in the vicinity of the welding point P or adjacent to the welding point P, but the positions thereof can be appropriately changed according to the shape of the support member 80. In the present embodiment, the opposing surface portion 15a is arranged so that the elongated plate-shaped support member 80 can be disposed on the electrode group 40 side of the welding point P between the first insulating sheets 15 and 16 and the second insulating sheet 14. , 16a and side portions 15b and 16b, openings 15d and 16d are formed adjacent to the welding point P in a portion along the corner portion.

  In addition, regarding the shapes of the openings 15 d and 16 d, the shape into which the support member 80 can be inserted includes being opened in a shape corresponding to the cross-sectional shape and dimensions of the support member 80. Therefore, when the plate-like support member 80 is used, the shapes of the openings 15 d and 16 d can be a long hole shape or a groove shape that is slightly larger than the cross-sectional shape of the support member 80. Moreover, when using the curved support material 80 etc., the opening parts 15d and 16d can be formed in the shape suitable for the insertion suitably. From the viewpoint of insulation, it is preferable that the openings 15d and 16d be as small as possible.

  Next, the operation of this embodiment will be described.

  In the first embodiment described above, the first insulating sheets 15 and 16 and the second insulating sheet 14 overlap on the conductive portions 40e and 40f, and these are joined at the welding point P on the current collector plates 21 and 31. Is done. Therefore, when the heater H is pressed from the outside of the electrode group 40 in order to weld the first insulating sheets 15 and 16 and the second insulating sheet 14, the first insulating sheets 15 and 16 and the second insulating sheet The insulating sheet 14 is supported by current collector plates 21 and 31. Therefore, the heat of the heater H is transmitted in a state where the first insulating sheets 15 and 16 and the second insulating sheet 14 are sandwiched between the heater H and the current collector plates 21 and 31 and pressure is applied. Welded.

  However, in this embodiment, the current collecting plates 121 and 131 are provided on one side of the electrode group 40 as shown in FIG. Therefore, on the side of the electrode group 40 where the current collecting plates 121 and 131 are not provided, the first insulating sheets 15 and 16 and the second insulating sheet 14 are supported by the current collecting plates 121 and 131 when they are joined. Can not do it. When the first insulating sheets 15 and 16 and the second insulating sheet 14 are welded without being supported from the electrode group 40 side, the heat and pressure of the heater H are not sufficiently transmitted to the first insulating sheet 15 and 16 and the second insulating sheet 14, which may result in poor welding. Is expensive.

  Therefore, in the present embodiment, the first insulating sheets 15 and 16 are portions that face the edge or end surface of the electrode group 40 in the winding axis direction D, and are the portions that do not overlap the second insulating sheet 14. Openings 15d and 16d into which the support member 80 can be inserted are provided in the surface portions 15a and 16a. Therefore, when the first insulating sheets 15 and 16 and the second insulating sheet 14 are welded, the support member 80 is inserted from the openings 15d and 16d, and the first insulating sheets 15 and 16 and the second insulating sheet 14 are inserted. The sheet 14 can be supported from the electrode group 40 side. As a result, the first insulating sheets 15 and 16 and the second insulating sheet 14 are sandwiched between the heater H and the support member 80, and the heat of the heater H is transmitted and welded in a state where pressure is applied. The Therefore, the first insulating sheets 15 and 16 and the second insulating sheet 14 can be favorably welded even on the side of the electrode group 40 where the current collector plates 121 and 131 are not provided, resulting in poor welding. Can be prevented.

  Further, the openings 15d and 16d are opened on the outer side of the flat portion 40b of the electrode group 40, that is, on the wide surface 4a side of the battery can 4 in the thickness direction of the electrode group 40, that is, in the direction perpendicular to the flat portion 40b. Therefore, by inserting the support member 80 into the openings 15d and 16d from the winding axis direction D of the electrode group 40, the support member 80 is reliably disposed between the electrode group 40 and the second insulating sheet 14. Can do. Thus, when the first insulating sheets 15 and 16 and the second insulating sheet 14 are welded at the welding point P, the first insulating sheets 15 and 16 and the second insulating sheet 14 are connected from the electrode group 40 side. It can be reliably supported by the support member 80.

<Third embodiment>
Next, a third embodiment of the present invention will be described with reference to FIG.

  FIG. 9 is an exploded perspective view of the insulating sheet according to the third embodiment.

  In the first and second embodiments, the first insulating sheets 15, 16 and the second insulating sheet 14 are covered with the first insulating sheets 15, 16 and the second insulating sheet 14, and then the first insulating sheets 15, 16 and the second insulating sheet 14 are They were superposed and joined by pressing against the opposing parts of the current collector plates 21 and 31. On the other hand, in the third embodiment, the first insulating sheets 15 and 16 and the second insulating sheet 14 are opposed to the curved portion 40c on the bottom surface of the electrode group 40, instead of the opposed portions of the current collector plates 21 and 31. It is characterized by joining the overlapping parts. That is, the first insulating sheets 15 and 16 and the second insulating sheet 14 are electrically conductive in the curved portion 40c on the bottom surface side of the battery can 4 facing the bottom surface of the battery can 4 among the pair of curved portions 40c of the electrode group 40. Joined by thermal welding at positions facing the portions 40e, 40f (see FIG. 3).

  According to this embodiment, since the first insulating sheets 15 and 16 and the second insulating sheet 14 are joined by the heater H before they cover the electrode group 40, it is possible to work in advance. There is a positional shift that may occur when the three insulating sheets are integrated before assembly so as to cover and wrap the electrode groups 40 of the first insulating sheets 15 and 16 and the second insulating sheet 14. This can prevent the assembly workability.

  In addition, this embodiment can also be implemented in combination with the first and second embodiments, thereby more reliably covering the electrode group 40 with the first insulating sheets 15 and 16 and the second insulating sheet 14. Can do.

  As mentioned above, although embodiment of this invention was explained in full detail, this invention is not limited to above-described embodiment, Various modifications are included. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to the one having all the configurations described. Further, a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment. In addition, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  For example, in the above-described embodiment, the case where the outermost periphery of the electrode group is a separator has been described as an example. However, since the electrode group is covered with an insulating sheet, the outermost periphery can be a positive electrode or a negative electrode instead of a separator. Thereby, the winding length of the separator in an electrode group can be shortened, and cost can be reduced.

  Moreover, in the above-described embodiment, a case has been described in which the first and second insulating sheets are partly joined to each other by thermal welding. However, the first and second insulating sheets may be configured such that all of the overlapping portions are joined by heat welding. Further, the first and second insulating sheets may have a configuration in which overlapping portions are welded linearly.

  Moreover, although the 2nd insulating sheet demonstrated the structure which the 2nd insulating sheet extended to the both ends edge of the winding axis direction of an electrode group in the above-mentioned embodiment, the 2nd insulating sheet does not necessarily have the structure which covers the full width of an electroconductive part. Good. That is, if the second insulating sheet extends from the mixture layer stacking region to the conductive portion so as to overlap the first insulating sheet at least at the joint portion between the first insulating sheet and the second insulating sheet. Good. For example, the structure which extends a 2nd insulating sheet to the near side of the both ends of an electrode group may be sufficient. Further, the mixture layer lamination is performed so that the second insulation sheet protrudes in a tongue-like shape from the mixture layer lamination region to the conductive portion, corresponding to the joint location between the first insulation sheet and the second insulation sheet. The structure which extended the 2nd insulating sheet which covers an area | region partially on the electroconductive part may be sufficient.

  In the above-described embodiment, the configuration in which the battery lid side of the insulating sheet is opened has been described. However, the tongue piece that insulates between the battery lid and the electrode group or between the battery lid and the current collector on the insulating sheet. A shaped portion may be provided.

DESCRIPTION OF SYMBOLS 1 Secondary battery 4 Battery can 4a Wide surface 5, 105 Insulating sheet 14 2nd insulating sheet 15, 16 1st insulating sheet 15d, 16d Opening part 21, 121 Positive electrode current collecting plate 31, 131 Negative electrode current collecting plate 40 Electrode Group 40b Plane portion 40d Mixture layer lamination region 40e Conductive portion (positive electrode conductive portion)
40f Conductive part (negative electrode conductive part)
41 Positive electrode 41a Positive metal foil 41b Positive electrode mixture layer 41c Exposed part (positive electrode exposed part)
42 Negative electrode 42a Negative metal foil 42b Negative electrode mixture layer 42c Exposed part (negative electrode exposed part)
D Winding axis direction

Claims (9)

The winding is performed by laminating and winding positive and negative electrodes in which a mixture layer is formed on one side edge of the metal foil so that the exposed portions are positioned at both ends in the winding axis direction. An electrode group in which a pair of conductive portions are formed at both ends in the axial direction and a mixture layer lamination region is formed between the pair of conductive portions, a battery can that houses the electrode group, the electrode group, and the battery A secondary battery comprising an insulating sheet interposed between the can and
The insulating sheet is
A pair of first insulating sheets interposed between the pair of conductive portions and the battery can;
It is thinner than the first insulating sheet, extends between the pair of first insulating sheets, is interposed between the mixture layer lamination region and the battery can, and the pair of conductive portions. A second insulating sheet that overlaps the first insulating sheet between the battery can and
The secondary battery, wherein the first insulating sheet and the second insulating sheet are joined to each other by thermal welding at least a part of an overlapping portion. The battery can is formed in a flat box shape having a pair of opposed wide surfaces,
The electrode group has a pair of flat portions opposed to the wide surface and a pair of curved portions formed continuously on both sides thereof,
The first insulating sheet and the second insulating sheet are bonded to each other by thermal welding at a position facing the curved portion on the battery can bottom side of the conductive portion of the electrode group. Item 11. The secondary battery according to Item 1. Further comprising a pair of current collector plates disposed between the wide surface of the battery can and the planar portion of the electrode group and connected to the pair of conductive portions;
The said 1st insulating sheet and the said 2nd insulating sheet are mutually joined by the heat welding between the said current collecting plate and the said battery can. The Claim 1 or Claim 2 characterized by the above-mentioned. Secondary battery. The first insulating sheet has an opening in a portion facing the end surface in the winding axis direction of the electrode group,
When the first insulating sheet and the second insulating sheet are bonded to each other by heat welding, the opening has a position and shape in which a support member disposed between the opening and the electrode group can be inserted. The secondary battery according to claim 3, wherein the secondary battery is opened. 5. The opening according to claim 4, wherein the opening is opened at a position communicating with the planar portion and the second insulating sheet in a direction perpendicular to the planar portion of the electrode group. Secondary battery. The secondary battery according to claim 5, wherein the thermal welding is spot welding. The battery can has an opening for inserting the electrode group,
The secondary battery according to claim 6, wherein the first insulating sheet and the second insulating sheet are joined by the spot welding in the vicinity of an opening of the battery can. In each of the pair of first insulating sheets, one portion of the battery can facing the wide surface and the other portion facing the wide surface are joined to the second insulating sheet one by one. The secondary battery according to claim 7, wherein: The secondary battery according to claim 7 , wherein each of the pair of first insulating sheets is joined to the second insulating sheet by spot welding at multiple points.

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