JP2016139532A - Rectangular secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rectangular secondary battery which does not inhibit the discharge of gas while improving insulation reliability.SOLUTION: A rectangular secondary battery described in the present invention includes: a rectangular battery can housing a winding group and having an opening; a battery lid closing the opening of the battery can and provided with an external terminal and a gas exhaust valve; and a sheet of a stretchable insulation film covering the external surface of the battery can and the battery lid and provided with a hole at a position facing the gas exhaust valve. The insulation film and the battery lid are bonded via an adhesive layer.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a prismatic secondary battery used for in-vehicle applications and the like.

  In recent years, secondary batteries with large capacity (Wh) have been developed as power sources for hybrid electric vehicles and pure electric vehicles. Among them, prismatic lithium ion secondary batteries with high energy density (Wh / kg) are of particular interest. Has been.

  In the prismatic lithium ion secondary battery, from the viewpoint of safety, the prismatic lithium ion secondary battery is required to have insulating properties and not to inhibit gas discharge from a safety valve provided in the prismatic lithium ion secondary battery. In patent document 1, the technique of sticking to a coated article by vacuuming the softened film is disclosed.

JP2013-252894A

  The battery described in Patent Document 1 has a structure in which a joint portion of a stretchable insulating film is arranged on the upper surface of the battery on which the terminals are arranged, and a gas exhaust valve is arranged on the upper surface of the battery on which the terminals are arranged. . For this reason, the joint portion of the insulating film that is harder than the other portions is disposed at the upper portion of the gas discharge valve, which may hinder gas discharge of the lithium ion secondary battery.

  On the other hand, Patent Document 1 discloses an example in which a stretchable insulating film is not disposed on a part of the upper surface of the battery on which the terminals are disposed. However, there is a problem that cannot be secured sufficiently.

  Therefore, an object of the present invention is to provide a prismatic secondary battery that does not inhibit gas discharge of the prismatic secondary battery while improving the insulation reliability of the prismatic secondary battery.

  In order to solve the above problems, a prismatic secondary battery according to the present invention is provided with a prismatic battery can that accommodates a winding group and has an opening, an opening of the battery can, and an external terminal and a gas discharge valve. The battery cover and the battery can cover the outer surface of the battery can and the battery cover, and has a stretchable insulating film having a hole at a position facing the gas discharge valve. The insulating film and the battery cover have an adhesive layer. Glued through.

  By the above means, it is possible to provide a rectangular secondary battery that improves the insulation reliability and does not hinder gas discharge.

External perspective view of prismatic secondary battery Exploded perspective view of prismatic secondary battery Exploded perspective view of winding group Figure before covering the prismatic secondary battery with insulating film Perspective view of insulating film in contact with prismatic secondary battery The figure before the insulating film on the battery lid side edge adheres to the prismatic secondary battery External perspective view of insulating film bonded to prismatic secondary battery AA sectional view of FIG. The figure which shows the BB cross section of FIG. The figure which shows the modification of FIG. The perspective view which stuck the insulating film concerning a 2nd Example to the square secondary battery. External perspective view and top view in which insulating film according to second embodiment is closely attached to prismatic secondary battery AA sectional view of FIG.

  Hereinafter, examples will be described with reference to the drawings.

<< First Example >>
FIG. 1 is an external perspective view of a prismatic secondary battery.

  The prismatic secondary battery 100 includes a battery can 1 and a lid (battery lid) 6. The battery can 1 has a side surface and a bottom surface 1d having a pair of opposed wide side surfaces 1b having a relatively large area and a pair of opposed narrow side surfaces 1c having a relatively small area, and an opening 1a above the side surface 1d. Have

  A wound group 3 is accommodated in the battery can 1, and an opening 1 a of the battery can 1 is sealed by a battery lid 6. The battery lid 6 has a substantially rectangular flat plate shape and is welded so as to close the upper opening 1 a of the battery can 1 to seal the battery can 1. The battery lid 6 is provided with a positive external terminal 14 and a negative external terminal 12. The wound group 3 is charged through the positive external terminal 14 and the negative external terminal 12, and power is supplied to the external load. The battery cover 6 is integrally provided with a gas discharge valve 10, and when the pressure in the battery container rises, the gas discharge valve 10 opens to discharge gas from the inside, and the pressure in the battery container is reduced. Thereby, the safety of the prismatic secondary battery 100 is ensured. Further, the battery lid 6 is provided with a liquid injection plug 11 for sealing the liquid injection port 9.

  FIG. 2 is an exploded perspective view of the prismatic secondary battery. The battery can 1 of the prismatic secondary battery 100 has a rectangular bottom surface 1d, a rectangular cylindrical wide side surface 1b, a narrow side surface 1c, and upper ends of the wide side surface 1b and the narrow side surface 1c. And an open opening 1a. A wound group 3 is accommodated in the battery can 1 via an insulating protective film 2.

  Since the wound group 3 is wound in a flat shape, the wound group 3 has a pair of opposed curved portions having a semicircular cross section and a flat portion formed continuously between the pair of curved portions. ing. The winding group 3 is inserted into the battery can 1 from one curved portion side so that the winding axis direction is along the lateral width direction of the battery can 1, and the other curved portion side is disposed on the upper opening side.

  The positive electrode foil exposed portion 34 c of the winding group 3 is electrically connected to the positive external terminal 14 provided on the battery lid 6 via a positive current collector plate (current collector terminal) 44. The negative electrode foil exposed portion 32 c of the wound group 3 is electrically connected to the negative external terminal 12 provided on the battery lid 6 via a negative current collector (current collector terminal) 24. Thereby, electric power is supplied from the winding group 3 to the external load via the positive electrode current collecting plate 44 and the negative electrode current collecting plate 24, and externally supplied to the wound group 3 via the positive electrode current collecting plate 44 and the negative electrode current collecting plate 24. The generated power is supplied and charged.

  In order to electrically insulate the positive electrode current collector plate 44 and the negative electrode current collector plate 24, and the positive electrode external terminal 14 and the negative electrode external terminal 12 from the battery lid 6, a gasket 5 and an insulating plate 7 are provided on the battery lid 6. It has been. Moreover, after injecting electrolyte solution into the battery can 1 from the liquid injection port 9, a liquid injection stopper 11 is joined to the battery lid 6 by laser welding to seal the liquid injection port 9, and the rectangular secondary battery 100 is sealed. To do.

Here, examples of the material for forming the positive electrode external terminal 14 and the positive electrode current collector plate 44 include an aluminum alloy, and examples of the material for forming the negative electrode external terminal 12 and the negative electrode current collector plate 24 include a copper alloy. Examples of the material for forming the insulating plate 7 and the gasket 5 include resin materials having insulating properties such as polybutylene terephthalate, polyphenylene sulfide, and perfluoroalkoxy fluororesin.

Further, the battery lid 6 is provided with a liquid injection hole 9 for injecting an electrolytic solution into the battery container. The liquid injection hole 9 is an injection stopper after the electrolytic solution is injected into the battery container. 11 is sealed. Here, as the electrolytic solution injected into the battery container, for example, a non-aqueous electrolytic solution in which a lithium salt such as lithium hexafluorophosphate (LiPF ₆ ) is dissolved in a carbonate-based organic solvent such as ethylene carbonate is used. Can be applied.

  The positive external terminal 14 and the negative external terminal 12 have a weld joint that is welded to a bus bar or the like. The weld joint has a rectangular parallelepiped block shape protruding upward from the battery lid 6, and has a configuration in which the lower surface faces the surface of the battery lid 6 and the upper surface is parallel to the battery lid 6 at a predetermined height position. Have.

  The positive electrode connecting portion 14 a and the negative electrode connecting portion 12 a have a cylindrical shape that protrudes from the lower surface of the positive electrode external terminal 14 and the negative electrode external terminal 12 and can be inserted into the positive electrode side through hole 46 and the negative electrode side through hole 26 of the battery lid 6. Have. The positive electrode connecting portion 14 a and the negative electrode connecting portion 12 a penetrate the battery lid 6 and are more inside the battery can 1 than the positive electrode current collector plate 44, the positive electrode current collector plate base 41 of the negative electrode current collector plate 24, and the negative electrode current collector plate base 21. The positive electrode external terminal 14, the negative electrode external terminal 12, the positive electrode current collector plate 44, and the negative electrode current collector plate 24 are integrally fixed to the battery lid 6. A gasket 5 is interposed between the positive electrode external terminal 14 and the negative electrode external terminal 12 and the battery cover 6, and an insulating plate is interposed between the positive electrode current collector plate 44, the negative electrode current collector plate 24 and the battery cover 6. 7 is interposed.

  The positive electrode current collector plate 44 and the negative electrode current collector plate 24 are a rectangular plate-shaped positive electrode current collector plate base 41, a negative electrode current collector plate base 21, and a positive electrode current collector plate base 41 that are arranged to face the lower surface of the battery lid 6. The negative electrode current collector plate 21 is bent at the side end and extends toward the bottom surface along the wide surface of the battery can 1 to form the positive electrode foil exposed portion 34c and the negative electrode foil exposed portion 32c of the wound group 3. It has a positive electrode side connection end portion 42 and a negative electrode side connection end portion 22 which are connected in a state of being opposed to each other. The positive electrode current collector plate base 41 and the negative electrode current collector plate base 21 are respectively formed with a positive electrode side opening hole 43 and a negative electrode side opening hole 23 through which the positive electrode connection part 14a and the negative electrode connection part 12a are inserted.

  The insulating protective film 2 is wound around the winding group 3 with the direction along the flat plane of the winding group 3 and the direction perpendicular to the winding axis direction of the winding group 3 as the central axis direction. The insulating protective film 2 is made of a single sheet or a plurality of film members made of synthetic resin such as PP (polypropylene), for example, and is a direction parallel to the flat surface of the wound group 3 and perpendicular to the winding axis direction. Has a length that can be wound around the winding center.

  FIG. 3 is an exploded perspective view showing a state in which a part of the wound electrode group is developed. The winding group 3 is configured by winding the negative electrode 32 and the positive electrode 34 in a flat shape with separators 33 and 35 interposed therebetween. In the winding group 3, the outermost electrode is the negative electrode 32, and the separators 33 and 35 are wound outside thereof. The separators 33 and 35 have a role of insulating between the positive electrode 34 and the negative electrode 32.

  The portion where the negative electrode mixture layer 32b of the negative electrode 32 is applied is larger in the width direction than the portion of the positive electrode 34 where the positive electrode mixture layer 34b is applied, so that the portion where the positive electrode mixture layer 34b is applied is The negative electrode mixture layer 32b is always sandwiched between the coated portions. The positive foil exposed portion 34c and the negative foil exposed portion 32c are bundled at a plane portion and connected by welding or the like. The separators 33 and 35 are wider than the portion where the negative electrode mixture layer 32b is applied in the width direction, but are wound at positions where the metal foil surface at the end is exposed at the positive electrode foil exposed portion 34c and the negative electrode foil exposed portion 32c. Therefore, it does not hinder bundle welding.

  The positive electrode 34 has a positive electrode active material mixture on both sides of a positive electrode foil that is a positive electrode current collector, and a positive electrode foil in which the positive electrode active material mixture is not applied to one end in the width direction of the positive electrode foil An exposed portion 34c is provided.

  The negative electrode 32 has a negative electrode active material mixture on both sides of a negative electrode foil that is a negative electrode current collector, and the negative electrode foil in which the negative electrode active material mixture is not applied to the other end in the width direction of the positive electrode foil An exposed portion 32c is provided. The positive electrode foil exposed portion 34c and the negative electrode foil exposed portion 32c are regions where the metal surface of the electrode foil is exposed, and are wound so as to be disposed on one side and the other side in the winding axis direction.

  Regarding the negative electrode 32, 10 parts by weight of polyvinylidene fluoride (hereinafter referred to as PVDF) is added as a binder to 100 parts by weight of amorphous carbon powder as a negative electrode active material, and N as a dispersion solvent. -A negative electrode mixture in which methylpyrrolidone (hereinafter referred to as NMP) was added and kneaded was prepared. This negative electrode mixture was applied to both surfaces of a 10 μm thick copper foil (negative electrode electrode foil) leaving a welded portion (negative electrode uncoated portion). Then, the negative electrode 32 with a negative electrode active material application part thickness of 70 micrometers which does not contain copper foil was obtained through drying, a press, and a cutting process.

  In this embodiment, the case where amorphous carbon is used as the negative electrode active material is exemplified, but the present invention is not limited to this, and natural graphite capable of inserting and removing lithium ions and various artificial graphite materials Carbonaceous materials such as coke, compounds such as Si and Sn (for example, SiO, TiSi2 etc.), or composite materials thereof may be used, and the particle shape is particularly limited, such as scaly, spherical, fibrous, or massive Is not to be done.

  Regarding the positive electrode 34, 10 parts by weight of flaky graphite as a conductive material and 10 parts by weight of PVDF as a binder are added to 100 parts by weight of lithium manganate (chemical formula LiMn 2 O 4) as a positive electrode active material. A positive electrode mixture in which NMP was added and kneaded as a dispersion solvent was prepared. This positive electrode mixture was applied to both surfaces of an aluminum foil (positive electrode foil) having a thickness of 20 μm leaving a welded portion (positive electrode uncoated portion). Thereafter, a positive electrode 31 having a thickness of 90 μm in the thickness of the positive electrode active material coating portion not including an aluminum foil was obtained through drying, pressing, and cutting processes.

  Further, in this example, the case where lithium manganate is used as the positive electrode active material is exemplified, but other lithium manganate having a spinel crystal structure or a lithium manganese composite oxide or layered in which a part is substituted or doped with a metal element A lithium cobalt oxide or lithium titanate having a crystal structure, or a lithium-metal composite oxide obtained by substituting or doping a part thereof with a metal element may be used.

Further, in this embodiment, the case where PVDF is used as the binder of the coating portion in the positive electrode 34 and the negative electrode 32 is exemplified, but polytetrafluoroethylene (PTFE), polyethylene, polystyrene, polybutadiene, butyl rubber, nitrile rubber. Polymers such as styrene butadiene rubber, polysulfide rubber, nitrocellulose, cyanoethyl cellulose, various latexes, acrylonitrile, vinyl fluoride, vinylidene fluoride, propylene fluoride, chloroprene, acrylic resins, and mixtures thereof. Further, as the shaft core, for example, a structure in which a resin sheet having higher bending rigidity than any of the positive electrode foil 34a, the negative electrode foil 32a, and the separator 33 is wound can be used.

  FIG. 4 is a view before covering the prismatic secondary battery 100 with the insulating film 50 having elasticity. The insulating film 50 is composed of a single-layer or multi-layer sheet or film member made of a colorless transparent or colored synthetic resin such as PP (polypropylene).

  As an example of a method of closely attaching the insulating film 50 to the prismatic secondary battery 100, for example, the bottom surface 1d of the prismatic secondary battery 100 is brought into close contact with the center of the insulating film 50 softened by heating, and the insulating film 50 is attached to the battery. There is a method in which the insulating film 50 is brought into close contact with the prismatic secondary battery 100 by vacuuming after being pulled up to the lid 6 side. In this embodiment, the insulating film 50 is brought into close contact with the battery can 1 by pulling up the insulating film 50 in the upward arrow direction in FIG. In this method, the insulating film 50 and the bottom surface 1d of the prismatic secondary battery 100, the two wide side surfaces 1b, and the two narrow side surfaces 1c are in close contact with each other. Thereafter, the battery lid 6 and the insulating film 50 are brought into close contact with each other. A method for bringing the insulating film 50 into close contact with the battery lid 6 will be described later.

  FIG. 5 is a view showing a perspective view in which the insulating film 50 is brought into close contact with the prismatic secondary battery 100. The insulating film 50 is brought into close contact with the prismatic secondary battery 100 using the method described above. First, the insulating film 50 is brought into close contact with the battery can 1 using the method described above, and the upper end is cut.

  FIG. 6 is a diagram showing a state before the insulating film 50 at the end portion on the battery lid 6 side is in close contact with the battery container.

  In order to use the prismatic secondary battery 100, it is necessary to expose the negative electrode external terminal upper surface 12 b and the positive electrode external terminal upper surface 14 b from the insulating film 50. Therefore, the upper end of the insulating film 50 whose upper end is cut by being brought into close contact with the battery can 1 using the above-described method is cut again. This re-cutting is a process for easily exposing the positive electrode external terminal 14 and the negative electrode external terminal 12 from the insulating film 50 and covering the battery container with the insulating film 50.

  The insulating film 50 is cut again to form a pair of insulating film protrusions 50 a 1 and 50 a 2 along the long side direction of the battery lid 6. At this time, the insulating film protrusions 50a1 and 50a2 protrude upward from the battery cover 6. However, the protrusion amounts of the insulating film protrusions 50a1 and 50a2 are both the length of the battery cover 6 in the short side direction (narrow side surface). It is preferable that the length of the insulating film protrusion 50a1 and the insulating film protrusion 50a2 be shorter than each other. By adopting such a structure, the overlapping portion of the insulating film protruding portion 50a1 and the insulating film protruding portion 50a2 can be reliably disposed on the battery lid 6. Therefore, it can suppress that the level | step difference produced by overlapping the insulating film 50 is provided on the wide side surface 1b of the battery can 1, and when securing the square secondary battery 100, it is fixed due to the difference in the thickness of the insulating film 50. Unevenness of binding force is suppressed, and as a result, the life of the prismatic secondary battery 100 is extended.

  In addition, the length of the insulating film protrusion 50a2 is preferably shorter than the length from the long side of the battery lid 6 to the gas discharge valve 10. By adopting such a structure, it is possible to prevent the insulating film protrusion 50a2 from blocking the gas discharge valve 10 and increasing the strength of the insulating film 50 on the gas discharge valve 10. Accordingly, the gas discharge of the rectangular secondary battery 100 is not further hindered.

  Further, when the upper end of the insulating film 50 is cut, a gas discharge hole 52 is formed in a portion facing the gas discharge valve 10 provided in the battery lid 6. By forming the gas discharge hole 52 at a portion facing the gas discharge valve 10, the gas discharge from the gas discharge valve 10 is not hindered. In the present embodiment, the size of the gas discharge hole 52 is smaller than the size of the gas discharge valve 10, but may naturally be the same size as the size of the gas discharge valve 10.

  Furthermore, by providing the two slit portions 51 in the insulating film corner 53 in close contact with the prismatic secondary battery 100, the insulating film corner 53 is divided into a narrow surface side corner portion 53a and a wide surface side corner portion 53b. The insulating film 50 can be easily folded back. In this embodiment, the slit 51 is provided so as to coincide with the center of the corner portion 1e at the boundary between the wide side surface 1b and the narrow side surface 1c, but the slit 51 is formed at the boundary between the wide side surface 1b and the corner portion 1e. 51 may be provided, or the slit 51 may be provided at the boundary between the narrow side surface 1c and the corner portion 1e. When the slit 51 is provided at the boundary between the wide side surface 1b and the corner portion 1e, the wide surface side corner portion 53b has a straight shape having no corners, so that it is easy to bend. In the case where the slit 51 is provided at the boundary, the narrow surface side corner portion 53a has a straight shape having no corner, so that it is easy to bend.

  In addition, it is preferable that the pair of wide surface side corners 53b of the insulating film do not overlap each other when folded to the battery lid 6 side. When the prismatic secondary battery 100 is assembled as a module, a module fixing member may be disposed on the outer side in the longer side of the battery lid 6 than the positive external terminal 14 and the negative external terminal 12. Therefore, by preventing the pair of wide surface side corners 53b of the insulating film from overlapping each other, the dimensional tolerance when assembled as a module can be kept small.

  In the description of the present embodiment, the insulating film 50 cutting process is performed in two stages, but naturally, the insulating film protrusions 50a1 and the like may be formed by separating the insulating film 50 in one stage. Alternatively, the insulating film protrusions 50a1 and the like may be formed by separating the insulating film 50 through two or more steps.

  By providing the two slit portions 51 in the two insulating film corners 53 described above, the insulating film 50 in the long side direction of the battery lid 6 is folded back and adhered to the battery lid 6, and then the short side of the battery lid 6. The direction of the insulating film 50 can be folded back to facilitate adhesion to the battery lid 6. The insulating film 50 may be folded back after the insulating film 50 in the short side direction is folded, and then the insulating film 50 in the long side direction may be folded back.

  Next, FIG. 7 shows an external perspective view and a top view in which the insulating film 50 is bonded to the square secondary battery 100. By providing an adhesive layer 55 (not shown; details shown in FIG. 8) on the entire outer surface of the battery lid 6, the insulating film 50 can be brought into close contact with the battery lid 6. Note that the entire outer surface of the battery cover 6 referred to here means, for example, the outer surface of the battery cover 6 except for the gas discharge valve 10 between the insulating film protrusion 51a and the battery cover 6. When the adhesive layer 55 is provided on the gas exhaust valve 10, not only the amount of adhesive used is increased, but also the cleavage of the gas exhaust valve 10 may be hindered. It is preferable that there is no.

  In the present embodiment, the adhesive layer 55 is provided on the entire outer surface of the battery lid 6, but the adhesive layer 55 may naturally be provided on a part of the outer surface of the battery lid 6. In this case, for example, it can be created by an act of, for example, providing an adhesive scattered on the battery lid 6. However, even when the adhesive layer 55 is partially provided, it is preferable to provide the adhesive layer 55 on the battery lid 6 so as to surround the gas discharge valve 10. As described above, the gas discharge hole 52 is provided at the position where the insulating film 50 faces the gas discharge valve 10. Therefore, there is a risk that moisture or the like may enter this portion. Therefore, in order to prevent water from entering between the insulating film 50 and the battery lid 6 and the battery can 1, the adhesive layer 55 is disposed on the battery lid 6 so as to surround the gas discharge valve 10. preferable.

  8 is a cross-sectional view taken along the line AA in FIG. By providing the adhesive layer 55 on the outer surface of the battery lid 6, the insulating film 50 can be brought into close contact with the battery lid 6. A specific structure will be described with reference to FIG. In this embodiment, the long insulating film protrusion 50a1 is covered with the short insulating film protrusion 50a2. This long insulating film protrusion 50a1 is structured to be bonded to the battery lid 6 via the adhesive layer 55. Further, the short insulating film protrusion 50a2 is also between the front end of the insulating film protrusion 50a1 and the short side direction end of the battery cover 6 (the end of the battery cover 6 on the side where the insulating film protrusion 50a2 is provided). Thus, the adhesive layer 55 is bonded. Therefore, it becomes the structure where peeling of the both ends of the insulating film protrusion part 50a1 and the insulating film protrusion part 50a2 was suppressed.

  The insulating film protrusion 50a2 is preferably in close contact with the long side of the battery lid 6 without a gap. If the insulating film protrusion 50a2 is not continuously adhered along the long side of the battery lid 6 without a gap, water or the like enters between the insulating film protrusion 50a1 and the insulating film 50a2, and the battery can This is because the insulating property of 1 may be lowered. Even if water or the like enters between the insulating film protrusion 50a1 and the insulating film protrusion 50a2 by adopting the above structure, water intrudes at the portion where the insulating film protrusion 50a2 and the battery can 6 are bonded. Therefore, it is possible to prevent a decrease in insulation.

  By adopting such a structure, it is possible to suppress peeling of the end portion of the insulating film 50 particularly when the stretchable insulating film 50 that easily peels at the end portion is used. Therefore, the insulation of the battery cover 6 is ensured.

  Next, FIG. 9 shows a BB cross-sectional view of FIG. As described above, the insulating film corner portion 53 is formed by the narrow side surface side corner portion 53a and the pair of wide side surface side corner portions 53b. In this embodiment, the pair of wide side surface portions 53b are folded back toward the battery lid 6 so as not to overlap each other, and are bonded to the adhesive layer 55 provided on the battery lid 6. Thereafter, the narrow side corner 53a is folded back toward the battery lid 6 and pressed to adhere to the adhesive layer exposed portion 55a provided between the pair of wide side corners 53b, as shown in FIG. Structure. By adopting such a structure, it is possible to easily prevent the narrow side surface corner portion 53a and the wide side surface side corner portion 53b from peeling without increasing the amount of adhesive used.

  FIG. 10 is a modification of FIG. 9 is different from the structure of FIG. 9 in that the adhesive layer 55 is also filled between the pair of wide side surface corners 53b, and the narrow side surface side corners 53a are arranged on one plane. . In the present modification, the adhesive layer 55 is filled between the pair of wide side corners 53b so as to have the same height as the pair of wide side corners 53b. By adopting such a structure, the amount of adhesive used is increased, but the possibility that the narrow surface side corner portion 53a is peeled off by the spring back can be suppressed. There is. In addition, since the unevenness on the narrow side surface side corner portion 53a is eliminated, the dimensional tolerance at the time of creating the module can be kept small.

  The present embodiment will be briefly described above. The prismatic secondary battery described in the present embodiment includes a rectangular battery can 1 that accommodates the winding group 3 and has an opening, closes the opening of the battery can 1, the positive electrode external terminal 14, the negative electrode external terminal 12, and the gas discharge valve 10. A battery lid 6 provided with a sheet, and a stretchable insulating film 50 that covers the outer surface of the battery can 1 and the battery lid 6 and has a hole 52 at a position facing the gas discharge valve 10. The insulating film 50 and the battery lid 6 are bonded via an adhesive layer 55. By adopting such a structure, it becomes possible to fix the stretchable insulating film 50 that is easily peeled off on the battery lid 6. Therefore, the insulation reliability on the battery lid 6 side can be secured while suppressing the inhibition of gas discharge of the gas discharge valve.

  Further, in the prismatic secondary battery described in this example, the battery lid 6 has a pair of long sides and a pair of short sides, the insulating film 50 is formed along the long sides of the battery lid 6, and the battery A pair of insulating film protrusions 50a1 and 50a2 are fixed to the lid 6, and the lengths of the pair of insulating film protrusions 50a1 and 50a2 are shorter than the short sides of the battery cover 6, respectively, and overlap portions are provided. Length. By adopting such a structure, it is possible to reliably provide the overlapping portion of the insulating film protruding portions 50a1 and 50a2 on the battery lid 6. Therefore, since it is possible to avoid providing a step caused by overlapping the insulating film protrusions 50a1 and 50a2 on the wide side surface 1b of the battery can 1, the difference in the thickness of the insulating film 50 when the prismatic secondary battery 100 is secured. Unevenness of the lashing force due to is suppressed, and as a result, the life of the prismatic secondary battery 100 is extended.

  Further, in the prismatic secondary battery described in the present embodiment, one of the pair of insulating film protrusions 50a1 and 50a2 is shorter than the length from the long side of the battery lid 6 to the gas exhaust valve 10. By adopting such a structure, it is possible to prevent the insulating film protrusion 50a2 from blocking the gas discharge valve 10 and increasing the strength of the insulating film 50 on the gas discharge valve 10. Accordingly, the gas discharge of the rectangular secondary battery 100 is not further hindered.

  Further, in the prismatic secondary battery described in this example, the adhesive layer 55 is provided between the insulating film protruding portion 50a1 and the battery lid 6, and is provided at a portion other than the gas discharge valve. By adopting such a structure, it is possible to ensure the insulation reliability of the battery lid 6 without hindering gas discharge by the adhesive layer.

  In the prismatic secondary battery described in this example, each of the pair of insulating film protrusions 50a1 and 50a2 is bonded to the adhesive layer 55. Therefore, the insulating film protrusion 50a1 and the insulating film protrusion 50a2 are prevented from peeling off at both ends, and the insulation reliability of the prismatic secondary battery 100 is improved.

<< Second Example >>
Next, a second embodiment will be described. In the first embodiment, the adhesive layer 55 is provided on the outer surface of the battery lid 6 and the insulating film protrusion 50a1 is brought into close contact with the battery lid 6. In this embodiment, the insulating film protrusion 50a1 and the insulating film protrusion 50a2 The difference between this embodiment and the first embodiment is that an adhesive layer is provided between the outer surface of the insulating film protruding portion a1 and the inner surface of the insulating film protruding portion 50a2 in the overlapping portion. In the first embodiment, the slits 51 are provided at the four corners of the insulating film 50 to facilitate the folding of the insulating film. However, when the insulating film 50 is formed, the four corners are connected to the battery. The difference between this embodiment and the first embodiment is that the insulating film 50 at the four corners is not required to be folded back by being in close contact with the lid 6. In the description of this embodiment, the same structure as that of the first embodiment is described using the same drawing numbers as those used in the first embodiment.

  FIG. 11 is a perspective view in which the insulating film according to this example is closely attached to the square secondary battery 100. In the first embodiment, the insulating film 50 in the short side direction of the battery lid 6 is formed perpendicular to the bottom surface 1d of the prismatic secondary battery 100. However, in this embodiment, as shown in FIG. Between the terminal 14 (or the negative electrode external terminal 12) and the end of the short side of the battery lid 6, the insulating film 50a3 is in direct contact with the outer surface of the battery lid 6 without an adhesive layer. In the first embodiment, a jig is disposed outside the positive electrode external terminal 14 and the negative electrode external terminal 12, and the bottom surface 1d of the square secondary battery 100 is brought into close contact with the central portion of the insulating film 50 softened by heating. The insulating film 50 was brought into close contact with the prismatic secondary battery 100 by vacuuming after pulling up the battery 50 toward the battery lid 6 side.

  In this embodiment, unlike the first embodiment, the shape of the jig for fixing the prismatic secondary battery 100 is a box-shaped jig (not shown) in which the positive electrode external terminal 14 and the negative electrode external terminal 12 are respectively accommodated. ), The bottom surface 1d of the prismatic secondary battery 100 is brought into close contact with the central portion of the insulating film 50 softened by heating, and the insulating film 50 is pulled up to the battery lid 6 side. Then vacuum. By creating in this way, as shown in FIG. 11, the structure is covered with the insulating film 50 from the side surface portion of the positive electrode external terminal 14 (or the negative electrode external terminal 12) to the short side of the battery lid 6. Therefore, since the insulating film 50 is hooked on the battery lid 6, the battery can 1 is prevented from falling off from the insulating film 50 during the process of forming the insulating film protrusions 50a1 and 50a2 after the jig is pulled out. And productivity is improved.

  In addition, the step of providing the slit 51 in the insulating film corner 53 and the step of folding the insulating film corner 53 to the battery lid side, which were necessary in the first embodiment, can be omitted, so that productivity is improved.

  FIG. 12 shows an external perspective view and a top view in which the insulating film 50 is in close contact with the square secondary battery 100. Also in this embodiment, as in the first embodiment, a pair of insulating film protrusions 50 a 1 and 50 a 2 are formed along the long side direction of the battery cover 6, and each cover the battery cover 6. Moreover, the gas discharge hole 52 is shape | molded by the insulating film protrusion part 50a1 similarly to the 1st Example. The gas discharge hole 52 is provided in the insulating film protrusion 50a1, so that the large surface of the battery cover 6 is covered with the insulating film 50 so that the insulating property of the rectangular secondary battery 100 is ensured but the gas discharge is not hindered. Structure.

  FIG. 13 is a cross-sectional view taken along the line AA in FIG. In this embodiment, as shown in FIG. 13, an adhesive layer 57 is provided on the insulating film protrusion 50 a 1, and the tip of the insulating film protrusion 50 a 2 is fixed to the insulating film protrusion 50 a 1 via the adhesive layer 57. By adopting such a structure, the ends of the insulating film 50 (insulating film protrusions 50a1 and 50a2) are fixed to each other, and therefore, peeling of the ends of the insulating film 50, which is a stretchable film, is suppressed. .

  In this embodiment, as in the first embodiment, an adhesive layer 55 is provided on the outer surface of the battery lid 6. Therefore, the insulating film protrusion 50a1 can be brought into close contact with the battery lid 6. Although not shown, an adhesive layer 55 may be provided on a part of the outer surface of the battery lid 6 so as to be in close contact with the battery lid 6.

  In particular, an adhesive layer 55 is provided on the entire outer surface of the battery cover 6 to adhere the insulating film protrusion 50a1, and an adhesive layer 57 is provided continuously without a gap in the long side direction of the tip of the insulating film protrusion 50a1. By adhering 50a2 and further adhering the insulating film protrusion 50a2 and the adhesive layer 55 in the same manner as in the first embodiment, a plurality of positions are fixed in the vicinity of the end of the insulating film 50 where peeling easily occurs. By adopting such a structure, the insulating film protruding portion 50a2 and the adhesive layer 57 and the insulating film protruding portion 50a2 and the adhesive layer 55 are routed from the end of the insulating film protruding portion 50a2 to the wide side surface 1b of the battery can 1. And the insulating film protruding portion 50a1 and the adhesive layer 55 and the insulating film protruding portion 50a2 and the adhesive layer 55 are bonded to each other through the path from the end of the gas discharge valve 10 to the wide side surface 1b of the battery can 1. Can be provided. In other words, at least two adhesive portions can be provided between the opened portion and the wide side surface of the battery can 1. Accordingly, water tightness is improved and insulation reliability is also improved.

  According to the present embodiment, the insulating film 50 is brought into close contact with the battery lid 6 so that peeling is suppressed. Therefore, insulation and water tightness are improved. In addition, when the gas discharge hole 52 is formed in a portion facing the gas discharge valve 10 provided in the battery lid 6 described above, the gas discharge valve 10 is opened when the pressure in the battery container rises. The insulating function can be added to the prismatic secondary battery 100 without hindering the function of discharging the gas from the battery and reducing the pressure in the battery container.

  The present embodiment will be briefly described above. In the prismatic secondary battery described in this example, an adhesive layer 57 is further provided between the pair of one insulating film protrusion and the other insulating film protrusion. With such a structure, the insulating film protruding portion 50a2 and the adhesive layer 57 and the insulating film protruding portion 50a2 and the adhesive layer 55 are routed from the end of the insulating film protruding portion 50a2 to the wide side surface 1b of the battery can 1. And the insulating film protruding portion 50a1 and the adhesive layer 55 and the insulating film protruding portion 50a2 and the adhesive layer 55 are bonded to each other through the path from the end of the gas discharge valve 10 to the wide side surface 1b of the battery can 1. A part can be provided, watertightness improves, and insulation reliability improves.

  In addition, the rectangular secondary battery described in this example is covered with an insulating film 53 from the side surface of the positive external terminal 14 (or the negative external terminal 12) to the end of the short side of the battery lid. With such a structure, the insulating film 50 is hooked on the battery lid 6, so that the battery is removed from the insulating film 50 during the process of forming the insulating film protrusions 50 a 1 and 50 a 2 after pulling out the jig. The can 1 can be prevented from falling off, and the productivity is improved.

  As mentioned above, although the Example of this invention was explained in full detail, this invention is not limited to the above-mentioned embodiment, In the range which does not deviate from the mind of this invention described in the claim, various designs It can be changed. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Furthermore, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

DESCRIPTION OF SYMBOLS 1 Battery can 1a Opening part 1b Wide side surface 1c Narrow side surface 1d Bottom surface 2 Insulation protective film 3 Winding group 5 Gasket 6 Battery cover 7 Insulation plate 9 Injection port 10 Gas discharge valve 11 Injection plug 12 Negative electrode external terminal 12a Negative electrode connection Portion 12b Negative electrode external terminal upper surface 14 Positive electrode external terminal 14a Positive electrode connection portion 14b Positive electrode external terminal upper surface 21 Negative electrode current collector base 22 Negative electrode side connection end 23 Negative electrode side opening hole 24 Negative electrode current collector plate 26 Negative electrode side through hole 32 Negative electrode 32a Negative electrode foil 32b Negative electrode mixture layer 32c Negative electrode foil exposed portion 33 Separator 34 Positive electrode 34a Positive electrode foil 34b Positive electrode mixture layer 34c Positive electrode foil exposed portion 35 Separator 41 Positive electrode collector plate base portion 42 Positive electrode side connection end portion 43 Positive electrode side opening hole 44 Positive electrode current collector plate 46 Positive electrode side through hole 50 Insulating film 50a1 Insulating film protruding part 50a2 Insulating film protruding part 51 Slit part 52 Gas exhaust hole 55 Adhesive layer 57 Adhesive layer 100 Rectangular secondary battery

Claims (7)

A rectangular battery can that houses a winding group and has an opening; a battery lid that closes the opening of the battery can and is provided with an external terminal and a gas discharge valve;
In the prismatic secondary battery that covers the outer surface of the battery can and the battery lid, and has a stretchable insulating film with a hole provided at a position facing the gas discharge valve,
The prismatic secondary battery, wherein the insulating film and the battery lid are bonded via an adhesive layer. The prismatic secondary battery according to claim 1,
The battery lid has a pair of long sides and a pair of short sides,
The insulating film is formed along the long side and has a pair of insulating film protrusions fixed to the battery lid,
Each of the pair of insulating film protrusions has a length shorter than a short side of the battery lid. The prismatic secondary battery according to claim 2,
One of said pair of insulating film protrusion parts is shorter than the length of the other insulating film protrusion part, The square secondary battery characterized by the above-mentioned. The prismatic secondary battery according to claim 3,
The prismatic secondary battery, wherein the adhesive layer is provided between the insulating film protrusion and the battery lid, and is provided at a portion other than the gas discharge valve. The prismatic secondary battery according to claim 4,
The pair of insulating film protrusions are bonded to the adhesive layer, respectively. The prismatic secondary battery according to claim 5,
A prismatic secondary battery, wherein an adhesive layer is further provided between the pair of one insulating film protrusion and the other insulating film protrusion. The prismatic secondary battery according to claim 6,
The prismatic secondary battery, which is covered with the insulating film from a side surface of the external terminal to an end of a short side of the battery lid.