JP2016100046A - Square secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a square secondary battery improved in insertability of a wound electrode body into a battery container.SOLUTION: A square secondary battery of the present invention comprises: a wound electrode body arranged by winding electrodes each having a mixture layer-uncoated part at one end, and having a curved part and a flat part; a battery container having an opening, in which the wound electrode body is enclosed so that the curved part thereof is opposed to a bottom face of the container; a lid which closes the opening of the battery container; external terminals disposed on the lid; collector plates which are electrically connected with the corresponding external terminals and the corresponding uncoated parts; and an insulative protection film arranged on an outer periphery of the wound electrode body. The insulative protection film has a push-up part serving to push up the curved parts of the uncoated parts toward the lid.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a prismatic secondary battery used for in-vehicle applications, for example.

  In recent years, prismatic lithium secondary batteries with high energy density have been developed as power sources for electric vehicles and the like. Since a secondary battery for in-vehicle use requires a larger capacity than that for a mobile phone or the like, a plurality of secondary batteries may be mounted. In the rectangular battery, a flat wound electrode body as a power generation element is accommodated in a rectangular battery container. The wound electrode body is configured by winding a positive electrode plate and a negative electrode plate in a state of being insulated with a separator interposed therebetween. A positive electrode current collector laminated portion in which positive electrode uncoated portions are bundled is provided on one side in the winding axis direction of the wound electrode body, and a negative electrode uncoated portion is bundled on the other side in the winding axis direction. In addition, a negative electrode current collector laminate is provided, and a positive electrode connection terminal is joined to the positive electrode current collector laminate, and a negative electrode connection terminal is joined to the negative electrode current collector laminate. The positive electrode connection terminal and the negative electrode connection terminal are electrically connected to, for example, the positive electrode external terminal and the negative electrode external terminal arranged on the same surface of the battery container such as a battery lid on the outside of the battery container. The structure is neutral, that is, the battery container is insulated from the wound electrode body.

  In this type of prismatic battery, the positive electrode current collector laminated portion, the negative electrode current collector laminated portion of the wound electrode body located inside the battery, and the positive electrode connecting terminal and the negative electrode connecting terminal connected to these are the inner wall of the battery container. In order to prevent a short circuit through the wound electrode body and to prevent the wound electrode body from being scratched when inserted into the battery container, the wound electrode body and the inner wall of the battery container Various materials have been proposed in which an insulating protective film is interposed between them.

  For example, the insulating protective film is a portion existing between a pair of wide surface forming portions that form a pair of wide surfaces facing the flat surface of the wound electrode body, and the pair of wide surface forming portions, and the battery container A bottom surface forming portion that forms a bottom surface that faces the bottom surface of the battery, and two pairs of narrow side surface forming portions that are respectively present on both sides of the pair of wide surface forming portions and form a narrow side surface between the wide surfaces of the battery container The narrow side surface forming portion disposed on the inner side folded into a bag shape is formed smaller than the narrow side surface forming portion disposed on the outer side, so that it can be easily inserted into the battery container. Is known (see, for example, Patent Document 1).

JP 2010-287456 A

  However, in the shape of the insulating protective film shown in Patent Document 1, the insertion property on the wide surface side of the wound electrode body is considered, but the insertion property on the narrow side surface of the wound electrode body is not considered at all. Not. Therefore, the battery still has a poor insertion property of the wound electrode body.

  In view of the above problems, an object of the present invention is to provide a prismatic secondary battery in which insertability of a wound electrode body into a battery container is improved.

  The prismatic secondary battery of the present invention that solves the above-mentioned problem is obtained by winding an electrode having a mixture layer uncoated portion at one end, a wound electrode body having a curved portion and a flat portion, and a wound electrode body Of the battery container having an opening, a battery container having an opening, a lid that closes the opening of the battery container, an external terminal disposed on the cover, an electrical connection with the external terminal, and an uncoated surface. An insulating protective film is disposed on the outer periphery of the wound electrode body, and the insulating protective film has a push-up portion that pushes up the curved portion of the uncoated portion to the lid side. It is characterized by having.

  ADVANTAGE OF THE INVENTION According to this invention, the square secondary battery which improved the insertability to the battery container of a winding electrode body can be provided.

External perspective view of prismatic secondary battery Exploded perspective view of prismatic secondary battery Exploded perspective view of wound electrode body Perspective view of power generation element assembly Development view of insulation protective film The perspective view which shows the positional relationship of an insulating protective film and a wound electrode body The perspective view which shows the state which wound the side cover part of the insulation protective film around the winding electrode body The perspective view which shows the state which wound the bottom face cover part of the insulation protective film around the wound electrode body The perspective view which shows the state which wound the side surface folding | turning part of the insulation protective film around the winding electrode body (A) is a figure which shows before an uncoated part is pushed up with an insulation protective film, (b) is a figure which shows the mode after an uncoated part is pushed up with an insulation protective film The perspective view which shows the insulation protective film of 2nd Embodiment, and the winding electrode body before insertion The perspective view which shows the state which inserted the wound electrode body in the insulating protective film of 2nd Embodiment.

<First embodiment>
Next, an embodiment of the present invention will be described.

  FIG. 1 is an external perspective view of a prismatic secondary battery according to the present embodiment, and FIG. 2 is an exploded perspective view of the prismatic secondary battery according to the present embodiment.

  The square secondary battery C <b> 1 includes a battery container 1 and a lid (battery lid) 6. A wound electrode body 3 is accommodated in the battery container 1, and an opening 1 a of the battery container 1 is sealed with a lid 6. The lid 6 is joined to the battery container 1 by laser welding to constitute a battery container sealed by the battery container 1 and the lid 6. The lid 6 is provided with a positive external terminal 8A and a negative external terminal 8B.

  The square secondary battery C1 is charged to the wound electrode body 3 via the positive external terminal 8A and the negative external terminal 8B, and supplies power to the external load. The lid 6 is integrally provided with a gas discharge valve 10. 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. The safety of the prismatic secondary battery C1 is ensured.

  The battery case 1 of the prismatic secondary battery C1 has a so-called square shape, a rectangular bottom surface portion 22, a rectangular tubular side wall portion 21 rising from the four sides of the bottom surface portion 22 in the cell height direction (+ Y direction), and a side wall portion. And an opening 1a opened toward the cell height direction at the upper end of 21. The side wall 21 of the battery case 1 includes a pair of wide surface portions 21a that are spaced apart from each other in the cell thickness direction (+ Z direction) and a pair of narrow surface portions that are spaced apart in the cell width direction (+ X direction) and face each other. 21b.

  The wound electrode body 3 is accommodated in the battery container 1 in a state of being wrapped in an insulating protective film 2. The wound electrode body 3 has a flat shape, and has a pair of flat portions 3a and a pair of curved portions 3b having a cross-sectional arc shape facing each other with the pair of flat portions 3a interposed therebetween. Yes. The wound electrode body 3 is inserted into the battery case 1 from the one curved portion 3b side, and is housed in the battery case 1 in a state where the wound axis direction is in the lateral direction along the cell width direction (+ X direction).

  The positive electrode foil connection portion 31d and the negative electrode foil connection portion 32d, which are uncoated portions of the wound electrode body 3, are at least partially bundled in a flat thickness direction to form a flat plate, The current collector terminal) 4A is joined to the positive electrode side connection end portion 42A and the negative electrode current collector plate (current collection terminal) 4B to the negative electrode side connection end portion 42B by ultrasonic welding. The base ends of the positive current collector 4A and the negative current collector 4B are connected to the positive external terminal 8A and the negative external terminal 8B, respectively. The lid 6 is provided with a gasket 5 and an insulating plate 7 to electrically insulate the positive electrode current collector plate 4A and the negative electrode current collector plate 4B, and the positive electrode external terminal 8A and the negative electrode external terminal 8B from the lid 6, respectively. ing.

  As the material of the battery case 1 and the lid 6, aluminum or aluminum alloy which is a metal material is used. Aluminum or an aluminum alloy is used as a material for the positive electrode current collector plate 4A and the positive electrode external terminal 8A. Copper or copper alloy is used as a material for the negative electrode current collector plate 4B and the negative electrode external terminal 8B.

  The positive external terminal 8A and the negative external terminal 8B have weld joints that are welded to a bus bar or the like (not shown). The welded joint has a rectangular parallelepiped block shape protruding upward from the lid 6, and is arranged so that the lower surface faces the surface of the lid 6 and the upper surface is parallel to the lid 6 at a predetermined height position. Yes.

  The positive electrode connecting portion 12A and the negative electrode connecting portion 12B have cylindrical shapes that protrude from the lower surfaces of the positive electrode external terminal 8A and the negative electrode external terminal 8B, respectively, and can be inserted into the positive electrode side through hole 6A and the negative electrode side through hole 6B. doing. 12 A of positive electrode connection parts and the negative electrode connection part 12B penetrate the cover 6, and are inside the battery container 1 rather than the positive electrode current collecting plate base 41A of the positive electrode current collecting plate 4A and the negative electrode current collecting plate 4B, and the negative electrode current collecting plate base 41B. The positive electrode external terminal 8A, the negative electrode external terminal 8B, the positive electrode current collector plate 4A, and the negative electrode current collector plate 4B are integrally fixed to the lid 6. A gasket 5 is interposed between the positive electrode external terminal 8A and the negative electrode external terminal 8B and the lid 6, and an insulating plate 7 is interposed between the positive electrode current collector plate 4A, the negative electrode current collector plate 4B and the lid 6. Intervened.

  The positive electrode current collector plate 4A and the negative electrode current collector plate 4B are a rectangular plate-shaped positive electrode current collector plate base portion 41A, a negative electrode current collector plate base portion 41B, a positive electrode current collector plate base portion 41A, which are disposed to face the lower surface of the lid 6. It is bent at the side end of the negative electrode current collector base 41B and extends to the can bottom 22 side along the wide side surface of the battery case 1 to the positive electrode foil connection part 31d and the negative electrode foil connection part 32d of the wound electrode body 3. It has a positive electrode side connection end portion 42A and a negative electrode side connection end portion 42B which are connected in a state of being overlapped facing each other. The positive electrode collector plate base 41A and the negative electrode collector plate base 41B are respectively formed with a positive electrode side opening hole 43A and a negative electrode side opening hole 43B through which the positive electrode connecting part 12A and the negative electrode connecting part 12B are inserted.

  The positive electrode external terminal 8A and the positive electrode current collector plate 4A constitute a positive electrode side terminal component, and the negative electrode external terminal 8B and the negative electrode current collector plate 4B constitute a negative electrode side terminal component. The positive electrode side terminal component and the negative electrode side terminal component are integrally assembled to the lid 6 via the gasket 5 and the insulating plate 7 to constitute a lid assembly. Then, the power generation element assembly (see FIG. 4) is configured by assembling the wound electrode body 3 to the lid assembly.

  The wound electrode body 3 is supported between the positive electrode current collector plate 4A and the negative electrode current collector plate 4B of the lid assembly, the winding axis direction extends parallel to the lid 6, and the flat surface is the lid 6 A pair of curved surfaces of the wound electrode body 3 are arranged separately on the lid 6 side and the can bottom 22 side of the battery case 1.

  The insulation protective film 2 covers the wound electrode body 3 assembled to the lid assembly from the outside together with the positive electrode current collector plate 4A and the negative electrode current collector plate 4B, and between the side wall 21 and the can in the battery container 1 Each is interposed between the bottom 22. The insulating protective film 2 is made of an insulating synthetic resin material, and insulates the battery container 1 from the wound electrode body 3, the positive current collector plate 4A, and the negative current collector plate 4B. The wound electrode body 3, so that the wound electrode body 3, the positive current collector plate 4A, and the negative current collector plate 4B are not in direct contact with the battery container 1 when an impact or vibration is applied to the battery C1 from the outside. The positive electrode current collector plate 4A and the negative electrode current collector plate 4B are protected. The configuration and operational effects of the insulating protective film 2 will be described later in detail.

  When the wound electrode body 3 is inserted into the battery container 1 from the opening 1a in a state where the periphery of the wound electrode body 3 is covered with the insulating protective film 2, the battery container 1 has a pair of wound electrode bodies 3. The flat portion 3a and the wide side surface of the side wall portion 21 of the battery case 1 are in contact with the insulating protective film 2 sandwiched therebetween, and have a size and shape that can be inserted by pressing with a slight pressing force. In addition, a slight gap is formed between the end surfaces on both sides in the winding axis direction of the wound electrode body 3 and the narrow side surface 21 b of the battery container 1. On the other hand, the wound electrode body 3 and the narrow side surface 21b may interfere with each other due to a dimension difference. When the wound electrode body 3 and the narrow side surface 21 b interfere with each other, a trouble occurs when the wound electrode body 3 is inserted into the battery container 1. Therefore, in the present invention, the shape of the insulating protective film 2 is devised. Details will be described later.

  The opening 1 a of the battery container 1 is closed by a lid 6 and sealed by laser welding the lid 6 to the battery container 1. Thereafter, the battery container 1 is filled with the electrolytic solution. The electrolytic solution is injected into the battery container 1 from the injection port 9 of the lid 6. The injection port 9 is closed by an injection plug 11 after the injection of the electrolytic solution, and sealed by laser welding the injection plug 11 to the battery lid 6.

  FIG. 3 is an exploded perspective view showing a state in which a part of the wound electrode body is developed.

  The wound electrode body 3 is an electrode body wound in a flat shape by superposing the positive electrode 31 and the negative electrode 32 with the separator 33 interposed therebetween, and a positive electrode mixture is formed on both end faces in the winding axis direction. A positive electrode uncoated portion 31c and a negative electrode uncoated portion 32c to which the layer 31b and the negative electrode mixture layer 32b are not applied are respectively disposed. In the wound electrode body 3, the outermost electrode body is the negative electrode 32, and the separator 33 is wound outside thereof.

  The separator 33 has a role of insulating between the positive electrode 31 and the negative electrode 32. The negative electrode mixture layer 32 b of the negative electrode 32 is formed larger in the width direction than the positive electrode mixture layer 31 b of the positive electrode 31. The positive electrode 31 and the negative electrode 32 have both ends of the positive electrode mixture layer 31b inside the both ends of the negative electrode mixture layer 32b so that the entire surface of the positive electrode mixture layer 31b is always opposed to the negative electrode mixture 32b. The parts are overlaid so that the parts are arranged. The separator 33 is a porous polyethylene resin having a thickness of 20 to 30 μm. The thickness of the separator 33 is preferably 0.01 mm to 0.50 mm, and more preferably 0.03 mm to 0.20 mm.

  The positive electrode 31 is obtained by applying a positive electrode mixture layer 31b on both surfaces of a positive foil 31a, and has an uncoated positive uncoated portion 31c on one side in the width direction of the positive foil 31a. The negative electrode 32 is obtained by applying a negative electrode mixture layer 32b on both surfaces of a negative electrode foil 32a, and has an uncoated negative electrode uncoated portion 32c on the other side in the width direction of the negative electrode foil 32a. The positive electrode uncoated portion 31c and the negative electrode uncoated portion 32c are arranged on opposite sides in the winding axis direction.

  The positive electrode foil 31a is an aluminum alloy foil having a thickness of about 20 to 30 μm, and the negative electrode foil 32a is a copper alloy foil having a thickness of about 15 to 20 μm. The positive electrode active material is a lithium-containing transition metal double oxide such as lithium manganate, and the negative electrode active material is a carbon material such as graphite capable of reversibly occluding and releasing lithium ions.

  FIG. 4 is a perspective view of the power generation element assembly.

  The wound electrode body 3 includes a positive electrode foil connection portion 31d and a negative electrode foil connection portion 32d formed by previously crushing the positive electrode uncoated portion 31c and the negative electrode uncoated portion 32c in the thickness direction, respectively. The positive electrode current collector plate 4A and the negative electrode current collector plate 4B are each joined by ultrasonic welding to assemble as a power generation element assembly.

  In the power generating element assembly, the wound electrode body 3 is arranged on one flat surface, that is, on the flat surface portion 3a on the front side shown in the + Z direction in the figure, and the winding end portion 33a of the separator 33 is on the lid 6 side. Is attached so as to be accommodated in the battery container 1 in a posture state in which the battery container 1 is disposed in the direction toward the can bottom 22 side. The position of the winding end portion 33 a of the separator 33 is on the flat surface portion 3 a on the front side of the wound electrode body 3, and may be arranged at a position that is biased toward the can bottom side from the center position of the wound electrode body 3. preferable. The adhesive tape 20a is attached so as to extend from the lid side to the bottom of the can with respect to the end 33a of the separator 33. For example, when the battery can 1 of the square secondary battery C1 constituting the assembled battery is expanded, the center position of the wide side surface 21a of the side wall portion 21 that is the most expanded portion in the battery can 1 is pressed by lashing. It is preferable to be as flat as possible without unevenness. Therefore, by arranging the winding end end portion 33a of the separator 33 at a position deviated from the center position of the wound electrode body 3 to the other curved surface side, the unevenness due to the step of the winding end end portion 33a is formed on the side wall portion 21. It is possible to prevent formation at the center position of the wide side surface.

  Next, the structure of the insulating protective film 2 that is a feature of the present invention will be described in detail.

  FIG. 5 is a development view of the insulating protective film 2. In the following, the insulating protective film is shown as being made of an opaque member, but is not limited to being opaque and may be transparent.

  The insulating protective film 2 has a side cover portion 51 that covers the side surface of the wound electrode body 3 and a bottom surface cover portion 52 that covers the curved surface of the wound electrode body 3 on the can bottom side. The side cover 51 is wound around the wound electrode body 3 with the direction orthogonal to the winding axis direction of the wound electrode body 3 as the central axis direction, and the side surface of the wound electrode body 3 is disposed on the positive electrode current collector plate 4A. The bottom face cover portion 52 has a configuration in which the negative electrode current collector plate 4B is covered from the outside, and the bottom cover portion 52 is a wound electrode with the direction along the winding axis direction of the wound electrode body 3 being continuous with the side surface cover portion 51 It has a structure that is wound around the body 3 and covers the curved surface on the bottom side of the can. In the insulating protective film 2, as shown in FIG. 5, the upper horizontally long rectangular portion forms the side surface cover portion 51, and the lower portion continuously protruding from the side surface cover portion 51 forms the bottom surface cover portion 52.

  The side cover portion 51 includes a back surface facing portion 51a (first flat surface facing portion) facing the flat surface portion 3a (the other flat surface) on the back surface side of the wound electrode body 3 and a back surface facing portion 51a. A pair of front facing portions 51b and 51c (a pair of first facing surfaces) that continuously protrude in the direction of separating from each other along the long side direction and face the flat portion 3a (one flat surface) on the front side of the wound electrode body 3 respectively. 2 plane part opposing part). In addition, between the back facing part 51a and the front facing parts 51b and 51c, a pair of end faces that face the end faces on both sides of the wound electrode body 3 and face the narrow face parts 21b of the battery case 1, respectively. Parts 51d and 51e are provided.

  The pair of front facing portions 51 b and 51 c are divided into one side and the other side in the long side direction of the side cover portion 51, and the front surface of the wound electrode body 3 when the side cover portion 51 is wound around the wound electrode body 3. It overlaps and covers the flat part 3a on the side. Preferably, the side end 51g on the one side in the long side direction and the side end 51f on the other side in the long side direction are predetermined in the winding axis direction of the wound electrode body 3 on the plane portion 3a. A gap is formed between the side end 51g and the side end 51f at a position separated by a distance d1 (see FIG. 7).

  When the side cover part 51 partially covers the flat part 3a on the front side of the wound electrode body 3, the front facing parts 51b and 51c have different lengths in the long side direction. The part 51c is longer than 51b, and the side end parts 51f and 51g are arranged on the flat part 3a of the wound electrode body 3 and at a position displaced to one side in the winding axis direction from the center position of the flat part 3a. Is done.

  The bottom cover part 52 is provided so as to protrude in a direction orthogonal to the long side direction of the side cover part 51 continuously to the lower end of the back facing part 51 a of the side cover part 51. The bottom cover portion 52 includes a curved surface facing portion 52a that faces the curved portion 3b on the can bottom side of the wound electrode body 3, and a curved surface when wound around the curved portion 3b on the can bottom side of the wound electrode body 3. A pair of folded piece portions 52b facing the flat surface portion 3a on the front side of the wound electrode body 3 continuously with the facing portion 52a and a pair of surfaces facing the end surface of the wound electrode body 3 continuously with the curved surface facing portion 52a. It has a flap part 52c.

  Further, the insulating protective film 2 includes a side cover portion 51 on the surface in contact with the pair of flap portions 52c facing the end surfaces of the wound electrode body 3, front facing portions 51b, 51c, and a folded piece portion 52b facing the flat portion 3a. Has a notch 53. Specifically, the notch 53 is formed in the back facing portion 51a, the front facing portions 51b and 51c, and the folded piece side portion 52b. As shown in FIG. 5, the cutout portion 53 is provided so as to be inclined from the curved surface facing portion 52a toward the upper end side (the lid 6 side) of the side surface cover portion, and the back facing portion 51a and the folded piece side portion 52b are respectively provided. The width is increased as the curved surface facing portion 52b is approached. In other words, the width of the back facing portion 51a becomes narrower as it approaches the curved surface facing portion 52a, and the width of the folded piece side portion 52b becomes narrower as it approaches the curved surface facing portion 52a. With such a structure, when the wound electrode body 3 is covered with the insulating film 2, the width of the portion of the insulating film 2 formed in a box shape that faces the wide surface portion 21a of the battery container 1 is the battery. The container 1 becomes narrower toward the bottom surface portion 22 side. Therefore, when the wound electrode body 3 covered with the insulating film 2 is inserted into the battery container 1, the interference with the narrow surface portion 21b of the battery container 1 is avoided, and the insertability is improved. If there is no notch 53, when the wound electrode body 3 covered with the insulating film 2 is inserted into the battery container 1, it interferes with the narrow surface part 21b of the battery container 1. , Insertion is worse. In addition, as will be described later, when the pair of flap portions 52c are bent into the end surface facing portions 51d and 51e, respectively, the inclination of the cutout portion 53 is approximately met. Therefore, the bending angle of the flap portion 52c, and consequently the push-up amounts of the positive electrode uncoated portion 31c and the negative electrode uncoated portion 32c of the wound electrode body 3 can be adjusted by the cut amount of the cutout portion 53.

The curved surface facing portion 52a has a length shorter than the length of the wound electrode body 3 in the winding axis direction and a width that curves along the curved portion 3b of the wound electrode body 3 and covers the entire curved portion 3b. doing. With such a structure, when the flap portion 52c is bent, the positive electrode uncoated portion 31c and the negative electrode uncoated portion 32c of the wound electrode body 3 can be pushed up to the lid 6 side.
The folded piece 52b is formed so as to protrude continuously from the curved surface facing portion 52a. The folded piece portion 52b is overlapped with the front facing portions 51b and 51c when the bottom cover portion 52 is rubbed against the curved surface on the can bottom side of the wound electrode body 3, and the front side of the wound electrode body 3 is overlapped. The flat surface 3a is partially covered.

  The pair of flap portions 52c are arranged so as to protrude from the both ends of the bottom surface cover portion 52 in a direction away from each other, along the notch portions 53 on the bottom surface side of the side surface cover portion 51, and to be wound electrodes. It is overlapped and fixed to the end face facing portions 51d and 51e of the body 3, respectively. By doing so, the pair of flap portions 52c partially covers the end surface of the wound electrode body 3, and the end surfaces on both sides in the winding axis direction of the wound electrode body 3 and the side wall portion 21 of the battery case 1 are narrow. It will be interposed between the surface part 21b. The principle of pushing up the positive electrode uncoated part 31c and the negative electrode uncoated part 32c of the wound electrode body 3 will be described later.

  Further, the end face facing portions 51d and 51e have projecting portions 51d1 and 51e1 projecting toward the cutout portion 53, respectively.

  The insulating protective film 2 is made of a single sheet or film member made of a synthetic resin such as PP (polypropylene). The thickness of the insulating protective film 2 is set to be thicker than the thickness of one separator 33 and thinner than three, and in this embodiment, the separator 33 is equivalent to one. The thickness of the insulating protective film 2 is set to 50 μm, which is about twice that thickness.

  In addition, although the case where PP was used as an example of the material of the insulating protective film 2 was shown, it is not limited to this. For example, PFA (polytetrafluoroethylene), PPS (polyphenylene sulfide), PET (polyethylene terephthalate) ) Or a synthetic resin of a material that does not react or change in quality due to the electrolytic solution.

  Next, the principle of how the insulating protective film is attached and the positive electrode uncoated portion 31c and the negative electrode uncoated portion 32c of the wound electrode body 3 are pushed up will be described with reference to FIGS.

  6 is a perspective view showing a positional relationship between the insulating protective film 2 and the wound electrode body 3, and FIG. 7 is a perspective view showing a state where the side cover portion 51 of the insulating protective film 2 is wound around the wound electrode body 3. 8 is a perspective view showing a state in which the bottom cover portion 52 of the insulating protective film 2 is wound around the wound electrode body 3, and FIG. 9 is a state in which the flap portion 52c of the insulating protective film 2 is wound around the wound electrode body 3. FIG.

  First, as shown in FIG. 6, the insulating protective film 2 is disposed on the power generation element assembly with the upper end portion of the insulating protective film 2 along the lower surface of the lid 6. Then, the back surface facing portion 51a of the side surface cover portion 51 of the insulating protective film 2 is disposed opposite to the flat portion 3a on the back surface side of the wound electrode body 3, and the boundary portion between the side surface cover portion 51 and the bottom surface cover portion 52 is disposed. Is positioned at the lower end of the flat portion 3 a on the back side of the wound electrode body 3.

  Next, both end portions (front facing portions 51b and 51c) of the side cover portion 51 of the insulating protective film 2 are connected to the positive electrode current collector plate 4A from the outside of the wound electrode body 3 as indicated by arrows i and ii in FIG. And it winds so that the whole negative electrode current collecting plate 4B may be covered.

Then, as shown in FIG. 7, the insulating protective film 2 has a side cover 51 wound around the side surface of the wound electrode body 3, and the front facing portions 51b and 51c are bonded from one side end 51g to the other by the adhesive tape 20b. It sticks over the side end 51f. The adhesive tape 20b is affixed to a position that covers the end portion 33a of the separator 33 exposed from the gap d1.
As for the position of the adhesive tape 20b, the lengths of the front facing portions 51c and 51b are different, and the positions of the side end portions 51f and 51g are wound on the flat surface 3a of the wound electrode body 3 and more than the central position of the flat surface 3a. Since it is arrange | positioned in the position displaced to the axial direction one side, the adhesive tape 20b which fixes the side edge parts 51f and 51g is also arrange | positioned in the position displaced.

  Further, the side end 51f of the front facing portion 51b and the side end 51g of the other front facing portion 51c are arranged at a position separated from each other by a predetermined distance d1 in the winding axis direction of the wound electrode body 3. A gap is formed between the end 51g and the side end 51f. The gap d1 is about 1 mm to 10 mm, and preferably 3 mm to 5 mm.

  Then, after the side cover 51 is wound, the bottom cover 52 is wound along the curved portion 3b on the can bottom side of the wound electrode body 3 as indicated by an arrow iii in FIG. The curved surface facing portion 52 a of the bottom surface cover portion 52 has a curved shape along the curved portion 3 b on the can bottom side of the wound electrode body 3.

  As shown in FIG. 8, the folded piece portion 52b is arranged so as to overlap the outside of the one front facing portion 51b and the other front facing portion 51c, and is fixed by the adhesive tape 20c. The adhesive tape 20c is attached from the folded piece portion 52b of the bottom surface cover portion 52 to the front facing portion 51c, and is disposed at a position that does not overlap the adhesive tape 20a and the adhesive tape 20b. The insulating protective film 2 is covered except for the end surface portion of the curved portion 3b on the side and the portion of the gap d1 provided between the side end portion 51f of the front facing portion 51b and the side end portion 51g of the front facing portion 51c. It will be in a broken state.

  Then, as shown by an arrow iv in FIG. 8, the curved portion of the wound electrode body 3 is arranged so that the flap portion 52 c follows the notch portion 53 on the bottom surface side of the side cover portion 51 after the folded piece portion 52 b is wound. The can bottom side positive electrode uncoated portion 131 and the can bottom side negative electrode uncoated portion 132 of 3b are disposed so as to be pushed up to the lid 6 side (+ Y direction). The positive electrode uncoated portion 131 and the negative electrode uncoated portion 132 are deformed even with a slight external force because the mixture is not applied. Therefore, by providing the notch 53 so that the curved surface facing portion 52a is shorter than the wound electrode body 3, the flap 52c is pulled up to the side cover 51 along the notch 53. The positive electrode uncoated portion 131 and the negative electrode uncoated portion 132 are applied with a force toward the lid 6 side. Then, the positive electrode uncoated portion 131 and the negative electrode uncoated portion 132 that are deformed by some force are deformed along the folded flap portion 52, and the battery container 1 from the side closer to the center of the wound electrode body 3. It becomes the structure where it was lifted more as it goes to the narrow surface part 21b side.

  Then, as shown in FIG. 9, the flap portion 52 c is arranged so as to overlap the end face facing portions 51 d and 51 e of the wound electrode body 3, fixed by the adhesive tape 20 d, and the end face of the wound electrode body 3 is partially covered And are interposed between the end surfaces on both sides in the winding axis direction of the wound electrode body 3 and the narrow surface portion of the side wall portion 21 of the battery case 1. By having such a structure, the insulating protective film 2 and the wound electrode body 3 have substantially the same shape. Therefore, the flap part 52 functioning as a push-up part has a tapered shape (tapered part 52 c 1), and the insertion property is improved when the battery part 1 is inserted.

  In the present embodiment, the end face facing portions 51d and 51e have the protruding portions 51d1 and 51e1, respectively. However, the protruding portions 51d1 and 51e1 may be cut off. On the other hand, when the end face facing portions 51d and 51e have the protrusions 51d1 and 51e1 as in the present embodiment, the protrusions 51d1 and 51e1 are formed on the flap 52c when the flap 52c is bent. It becomes the form arrange | positioned in the form wound up inside. With this arrangement, when the wound electrode body 3 is inserted into the battery container 1, the positive electrode uncoated part 131 and the negative electrode uncoated part 132 that first contact the battery container 1 have the tapered part 52 c 1 and the protrusion. It will be protected by the two films 51d1 and 51e1. Therefore, since the exposure of the wound electrode body 3 can be prevented, it is possible to improve the insulation reliability while improving the insertion property of the wound electrode body 3 into the battery container 1.

  Moreover, there is no restriction | limiting in particular about the angle of the notch part 53, However, The edge part by the side of the lid | cover 6 of the notch part 53 shall be below the lower end of the positive electrode current collecting plate 4A (or the negative electrode current collecting plate 4B). Is preferred. By adopting such a structure, the push-up amount of the positive electrode uncoated portion 131 and the negative electrode uncoated portion 132 is not excessively increased, and the influence of strain on the wound electrode body 3 caused by the push-up is reduced. I can do it.

  In the present embodiment, the cutout portion 53 has a triangular shape, but the same effect can be obtained even when the shape has a curvature. By making the cutout portion 53 into a shape having a curvature, the flap portion 52 also has a structure having a curvature, and the insertability is improved.

  10A shows a state before the positive electrode uncoated portion 131 (or negative electrode uncoated portion 132) is pushed up by the insulating protective film 2, and FIG. 10B shows the positive electrode uncoated portion 131 by the insulating protective film 2. The state after the (or negative electrode uncoated portion 132) is pushed up is shown. In this figure, the state on the positive electrode side will be described as a representative.

  As shown in FIG. 10A, since the positive electrode mixture 31b is not applied to the positive electrode uncoated portion 31c (the positive electrode uncoated portion 131 on the bottom side), the wound electrode is welded by the positive foil connecting portion 31d. When pulled to the center of the body 3, the wound electrode body 3 is disposed on the inner side of the contour (a region surrounded by the flat portion 3 a and the curved portion 3 b when viewed from the side surface side of the wound electrode body 3). Become. The positive electrode uncoated portion 31c (the positive electrode uncoated portion 131 on the bottom side) does not include the positive electrode mixture 31b as described above, and thus has a large gap and is deformed even with a slight force. Therefore, when a force is applied from the insulating protective film 2 as shown in FIG. 10B, the positive electrode uncoated portion 131 is pushed up to the lid 6 side by a push-up distance L corresponding to the force. At this time, the width of the positive electrode uncoated portion 131 changes from H1 to H2. In addition, since the width H1 of the positive electrode uncoated portion 131 before being pushed up is smaller than the thickness of the wound electrode body 3, the width H2 of the positive electrode uncoated portion 131 after being pushed up is also the thickness of the wound electrode body 3. And the following. Therefore, even if the positive electrode uncoated portion 131 is pushed up, the positive electrode uncoated portion 131 is not caught by the wide surface portion 21a of the battery container 1 and the insertability does not deteriorate.

<Second Embodiment>
Next, a second embodiment will be described. In the first embodiment, the insulating film 2 is composed of a single sheet, but in this embodiment, the insulating protective film has a bag shape. In addition, about the structure similar to 1st embodiment, it demonstrated using the drawing number similar to the drawing number used in 1st embodiment.

  FIG. 11 is a perspective view showing the insulating protective film 102 of the second embodiment and the wound electrode body 3 before insertion. The insulating protective film 102 according to the second embodiment has a bag shape that wraps the power generating element assembly excluding the curved surface on the lid 6 side (+ Y direction) of the wound electrode body 3, and both corners 103 on the bottom side. Is rounded or chamfered when viewed from the wide side.

  FIG. 12 is a perspective view showing a state where the wound electrode body 3 is inserted into the insulating protective film 102 of the second embodiment. By inserting the wound electrode body 3 into the insulating protective film 102 of the second embodiment, the corner portions 103 on both sides on the bottom surface side function as push-up portions, and the positive electrode on the can bottom side of the curved portion of the wound electrode body 3 The uncoated part 131 and the negative electrode uncoated part 132 on the bottom side of the can are pushed up to the battery lid side (+ Y direction). In this state, it is inserted into the battery container 1. Therefore, when inserting into the battery container 1, the positive electrode uncoated portion 131 and the negative electrode uncoated portion 132 are each prevented from interfering with the narrow surface portion 21 b, and the insertability is improved.

  In the present embodiment, the insulating protective film 102 having a single bag shape is used. Therefore, it is difficult to deal with unevenness in the size of the wound electrode body 3 as in the first embodiment. On the other hand, since it is not necessary to fix the insulating protective film with an adhesive tape, the surface of the insulating protective film 102 of this embodiment overlaps or protects the insulating tape as compared with the insulating protective film 102 of the first embodiment. There is no overlap by the film, and there is no unevenness. Therefore, the portion that is caught when inserted into the battery container 1 is eliminated, so that the insertability into the battery container 1 is improved.

  The present invention will be briefly described above. In the prismatic secondary battery according to the present invention, the electrode (31, 32) having the mixture layer uncoated portion (31c, 32c) at one end is wound, and the curved portion (3b) and the flat portion (3a) are wound. A wound electrode body (3), a battery container (1) having an opening (1a) and a curved portion (3b) of the wound electrode body (3) so as to face the bottom surface, and a battery container The lid (6) that closes the opening (1a) of (1), the external terminals (8A, 8B) disposed on the lid (6), and the external terminals (8A, 8B) are electrically connected and uncoated Current collector plates (4A, 4B) connected to the working parts (31c, 32c), and an insulating protective film (2, 102) is arranged on the outer periphery of the wound electrode body (3) to protect the insulation. The film (2, 102) has a push-up portion that pushes up the curved portion of the uncoated portion (131, 132) toward the lid. By adopting such a structure, the end of the uncoated part on the bottom side of the can is pushed up in advance and the interference with the narrow surface part of the battery container is eliminated, so that the winding electrode body can be inserted into the battery container. Will improve.

  In the prismatic secondary battery according to the present invention, the insulating protective film (2) is continuously formed from the curved surface facing portion (52a) facing the curved portion (3b) of the wound electrode body (3). And the push-up portion is formed by folding the flap portion (52a) toward the lid (6). With such a structure, even if there is a variation in the size of the wound electrode body in production, the yield can be improved because it can be adjusted by bending the flap portion.

  Further, in the rectangular secondary battery according to the present invention, the insulating protective film (2) has a facing portion (51a, 51b, 51c) facing the flat portion (3a) of the wound electrode body (3), The facing portion (51a, 51b, 51c) includes a notch portion (53) having an inclination that continuously increases as it approaches the curved surface facing portion (52a), and the flap portion (52c) has a notch portion ( 53). By adopting such a structure, the push-up amount of the uncoated part can be determined based on the inclination during production, so that productivity is improved.

  Further, in the prismatic secondary battery according to the present invention, the insulating protective film (2) has end face facing portions (51d, 51e) facing the end face of the wound electrode body (3), and the end face facing portion (51d). , 51e) have protrusions (51d1, 51e1) disposed between the uncoated portions (31c, 32c) and the flap portions (52c). By adopting such a structure, the uncoated part on the can bottom side is protected by the two films of the flap part and the protruding part, and the protection of the wound electrode body can be improved. Therefore, it is possible to improve the insulation reliability while improving the insertion property of the wound electrode body into the battery container.

  In the prismatic secondary battery according to the present invention, the end of the notch 53 is formed below the lower end of the current collector plate (4A, 4B). By adopting such a structure, the push-up amount of the uncoated portion does not become excessively large, and the influence of strain on the wound electrode body caused by the push-up can be reduced.

  In the prismatic secondary battery according to the present invention, the width (H2) in the thickness direction of the wound electrode body 3 of the uncoated portion (31c, 32c) is equal to or less than the thickness of the wound electrode body (3). . By adopting such a structure, even if the uncoated part is pushed up, it is not caught by the wide surface part of the battery container and the insertability is not deteriorated.

  In the prismatic secondary battery according to the present invention, the insulating protective film (102) is constituted by a single film having a bag shape. By adopting such a structure, there is no overlap of adhesive tape or insulation protective film, and there is no unevenness, and there is no part that gets caught when inserting into the battery container, so the insertability to the battery container is further improved To do.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various designs can be made without departing from the spirit of the present invention described in the claims. 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 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. Furthermore, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

C1 Square secondary battery 1 Battery can 1a Opening portion 2 Insulating protective film 3 Winding electrode body 3a Flat surface portion 3b Curved portion 4A Positive electrode current collector plate 4B Negative electrode current collector plate 5 Gasket 6 Lid 6A Positive electrode side through hole 6B Negative electrode side through hole 7 Insulation plate
8A Positive electrode external terminal 8B Negative electrode external terminal 9 Injection port 10 Gas discharge valve 11 Injection plug 12A Positive electrode connection part 12B Negative electrode connection part 20a Adhesive tape 20b Adhesive tape 20c Adhesive tape 20d Adhesive tape 21 Side wall part 22 Can bottom 31 Positive electrode 31a Positive electrode foil 31b Positive electrode mixture 31c Positive electrode foil exposed portion 31d Positive electrode foil connection portion 32 Negative electrode 32a Negative electrode foil 32b Negative electrode mixture 32c Negative electrode foil exposed portion 32d Negative electrode foil connection portion 33 Separator 33a Whip end portion 51 Side cover portion 51a Flat surface Opposing portions 51b, 51c Front facing portions 51f, 51g Side end portion 52 Bottom cover portion 52a Curved surface facing portion 52b Folding piece portion 52c Flap portion 52d Tip portion 53 Notch portion 131 Positive electrode uncoated portion 132 on can bottom side Can bottom Side negative electrode uncoated part 102 insulating protective film 103 corner part

Claims (8)

Winding an electrode having a mixture layer uncoated part at one end, a wound electrode body having a curved part and a flat part,
The curved electrode body is housed so as to face the bottom surface, and a battery container having an opening;
A lid for closing the opening of the battery case;
An external terminal disposed on the lid;
In the rectangular secondary battery having a current collector plate electrically connected to the external terminal and connected to the uncoated portion,
An insulating protective film is disposed on the outer periphery of the wound electrode body,
The insulating protection film has a push-up portion that pushes up the curved portion of the uncoated portion toward the lid. The prismatic secondary battery according to claim 1,
The insulating protective film has a flap portion formed continuously from a curved surface facing portion facing the curved portion of the wound electrode body,
The prismatic secondary battery according to claim 1, wherein the push-up portion is formed by bending the flap portion toward the lid. The prismatic secondary battery according to claim 2,
The insulating protective film has a facing portion facing the flat portion of the wound electrode body,
The facing portion includes a notch portion having a slope that continuously increases in width as it approaches the curved surface facing portion,
The square secondary battery, wherein the flap portion is bent along the inclination of the cutout portion. The prismatic secondary battery according to claim 3,
The insulating protective film has an end surface facing portion facing the end surface of the wound electrode body,
The prismatic secondary battery according to claim 1, wherein the end face facing portion has a protruding portion disposed between the uncoated portion and the flap portion. The prismatic secondary battery according to claim 4,
The prismatic secondary battery according to claim 1, wherein an end of the notch is formed below a lower end of the current collector plate. The prismatic secondary battery according to claim 5,
The prismatic secondary battery, wherein the slope has a curvature. The prismatic secondary battery according to claim 6,
The square secondary battery, wherein a width of the uncoated portion in the thickness direction of the wound electrode body is equal to or less than a thickness of the wound electrode body. The prismatic secondary battery according to claim 1,
The insulating protective film is a rectangular secondary battery characterized in that it is constituted by a single film having a bag shape.