JP2015056359A - Square secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a square secondary battery the orientation of the positive electrode side and negative electrode side of which can be confirmed from the can bottom side.SOLUTION: A square secondary battery C1 including a battery can having a rectangular can bottom surface, a battery lid for sealing an opening facing the can bottom surface of the battery can, and a positive electrode external terminal and a negative electrode external terminal provided on the battery lid, is further provided with an insulation layer 13 covering the outer surface of the battery can 1. The insulation layer 13 is provided with a can exposing parts 51, 52 for exposing a part of the can bottom surface 21, and the can exposing parts 51, 52 have an asymmetric shape with reference to a center line C1 orthogonal to the long side of the can bottom surface.

Description

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

  In recent years, prismatic lithium ion 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 a rectangular secondary 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.

  A plurality of these square secondary batteries are combined in series or in parallel to form an assembled battery, which is used as a power source for industrial or vehicle use. If a plurality of prismatic secondary batteries are arranged in a narrow area, the battery can may be short-circuited to the external terminal of the prismatic secondary battery, and therefore it is known to have a structure in which an insulating layer is provided on the surface of the battery can. (For example, refer to Patent Document 1).

  Various types of prismatic secondary batteries of this type have been proposed in which a polarity display is provided in the vicinity of the positive external terminal and the negative external terminal. For example, a structure is disclosed in which an external insulator disposed between a lid, a positive external terminal, and a negative external terminal has a polarity display (see, for example, Patent Document 2).

JP 2011-181485 JP JP 2011-71104 A

In the case of the above-described conventional configuration, the external insulator is provided on the battery lid side, and the polarity display cannot be viewed from the can bottom side. Therefore, in a situation where the polarity display of the external insulator cannot be confirmed, it is unclear which of the battery width direction one side or the other side is the positive electrode side or the negative electrode side, and the direction of the positive electrode side or the negative electrode side of the battery is recognized. The battery may be accidentally placed on the opposite side.
This invention aims at provision of the square secondary battery which can confirm direction of the positive electrode side and negative electrode side of a battery from the can bottom side.

  The prismatic secondary battery of the present invention that solves the above problems is provided with a rectangular battery can having a rectangular can bottom, a battery lid that seals an opening facing the bottom of the can, and the battery lid. A prismatic secondary battery having a positive electrode external terminal and a negative electrode external terminal, having an insulating layer covering the outer surface of the battery can, wherein the insulating layer exposes a portion of the bottom surface of the can An exposed portion is provided, and the can exposed portion has an asymmetric shape with respect to a center line orthogonal to the long side of the bottom surface of the can.

  According to the present invention, the orientation of the positive electrode side and the negative electrode side of the battery can be confirmed from the can bottom side by setting the relationship between the can exposed portion on the bottom surface of the can and the direction of the battery in advance. Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

1 is an external perspective view of a prismatic secondary battery according to a first embodiment. The disassembled perspective view of the square secondary battery concerning 1st Embodiment. The exploded perspective view of a wound electrode body. The external appearance perspective view of the square secondary battery which shows the state which expand | deployed some adhesive sheets. The development view of an adhesive sheet. The external appearance perspective view which shows an example of the square secondary battery in 1st Embodiment. The bottom view which shows the square secondary battery of FIG. 6A from the can bottom side. The external appearance perspective view of the assembled battery concerning 1st Embodiment. AA line sectional view of an assembled battery shown in FIG. The perspective view explaining the assembly method of the assembled battery concerning 1st Embodiment. The exploded perspective view of the square secondary battery explaining other examples of an insulating layer. The perspective view of the square secondary battery explaining the other Example of a can exposure part. The bottom view which shows the square secondary battery of FIG. 11A from the can bottom side. The expanded view which shows an example of the adhesive sheet which forms the can exposure part shown to FIG. 11A. The expanded view which shows an example of the adhesive sheet which forms the can exposure part shown to FIG. 11A. The bottom view of the square secondary battery explaining other examples of a can exposure part. The bottom view of the square secondary battery explaining other examples of a can exposure part. The bottom view of the square secondary battery explaining other examples of a can exposure part. The external appearance perspective view which shows an example of the square secondary battery concerning 2nd Embodiment. The bottom view shown from the can bottom side of the square secondary battery of FIG. 14A.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In the following embodiments, a case of a prismatic lithium ion secondary battery used in a hybrid vehicle or an electric vehicle will be described as an example of a prismatic secondary battery.

<First embodiment>
What is characteristic in the present embodiment is that an insulating layer that covers the outer surface of the battery can is formed of an adhesive sheet.

  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 can 1 and a lid (battery lid) 6. In the battery can 1, a wound electrode body 3 (see FIG. 3) is accommodated, and the opening 100 of the battery can 1 is sealed with a lid 6.

  The battery can 1 of the square secondary battery C1 has a so-called square shape, a rectangular can bottom surface 21, a rectangular tubular side wall surface 22 rising from the can bottom surface 21, and an upper end of the side wall surface 22 facing the can bottom surface 21. And an opening 100 opened upward.

  The bottom surface 21 of the can has a rectangular shape, and the side wall surface 22 of the battery can 1 has a pair of wide surfaces 22a and 22b rising from a pair of opposed long sides of the bottom surface 21 of the can and a pair rising from a pair of short sides. Narrow surfaces 22c and 22d. The corners between the wide surfaces 22a and 22b and the narrow surfaces 22c and 22d of the side wall surface 22 and the corners between the side wall surface 22 and the can bottom surface 21 have a circular arc shape (R shape), respectively. Chamfering is performed. An adhesive sheet 13 is attached to the outer surface of the battery can 1 to form an insulating layer.

  The lid 6 is joined to the battery can 1 by laser welding to constitute a battery container sealed by the battery can 1 and the lid 6. The lid 6 is provided with a positive external terminal 8A and a negative external terminal 8B. The positive external terminal 8 </ b> A and the negative external terminal 8 </ b> B are arranged at positions separated from each other on both sides in the long side direction of the lid 6. The wound electrode body 3 (see FIG. 2) is charged via the positive external terminal 8A and the negative external terminal 8B, and power is supplied to the external load. In addition, the lid 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. Is done. Thereby, the safety of the square secondary battery C1 is ensured. The gas discharge valve 10 is arranged at an intermediate position between the positive external terminal 8A and the negative external terminal 8B of the lid 6.

Next, with reference to FIG. 2, the structure in the battery can 1 of the square secondary battery C1 will be described.
A wound electrode body 3 is accommodated in the battery can 1 via an insulating protective film 2. Since the wound electrode body 3 is wound in a flat shape, the wound electrode body 3 has a pair of opposed curved portions having a semicircular cross section and a plane portion formed continuously between the pair of curved portions. doing. The wound electrode body 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.

At least a part of the positive electrode foil connection part 31d and the negative electrode foil connection part 32d, which are the flat part of the wound electrode body 3 and the electrode foil exposed part, are bundled into a flat plate shape. (Electrical terminal) 4A and one end of the negative electrode current collector plate (current collecting terminal) 4B are overlapped and connected.
The other end of the positive electrode current collector plate 4A and the other end of the negative electrode current collector plate 4B are connected to the positive electrode external terminal 8A and the negative electrode external terminal 8B, respectively.

  In order to electrically insulate the positive electrode collector plate 4A and the negative electrode collector plate 4B, and the positive electrode external terminal 8A and the negative electrode external terminal 8B from the lid 6, a gasket 5 and an insulating plate 7 are provided on the lid 6, respectively. Yes. Moreover, after pouring electrolyte solution into the battery can 1 from the liquid injection port 9, the liquid injection stopper 11 is joined to the cover 6 by laser welding, the liquid injection port 9 is sealed, and the square secondary battery C1 is sealed. .

  Furthermore, the square secondary battery C <b> 1 includes a side wall surface 22 composed of four surfaces of the battery can 1 and an adhesive sheet 13 attached to the can bottom surface 21 composed of one surface. Although details will be described later, the adhesive sheet 13 is attached to the bottom surface 21 and the side wall surface 22 of the battery can 1, and the battery can except for the welded portion between the lid 6 and the battery can 1 described above on the side wall surface 22. Affixed to almost the entire circumference of 1

  As a material for the pressure-sensitive adhesive sheet 13, a resin material such as polyester, polypropylene, or polyimide is used as a base material. An adhesive layer is provided on one side of the substrate, and an acrylic or silicon adhesive is used for the adhesive layer. The total thickness of the pressure-sensitive adhesive sheet 13 including the base material and the pressure-sensitive adhesive layer is 30 to 80 μm. The pressure-sensitive adhesive sheet 13 has a color different from that of the outer surface of the battery can 1. In the present embodiment, the battery can 1 has a metallic color, and the adhesive sheet 13 has a green color.

  As the material for the battery can 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 weld joint has a rectangular parallelepiped block shape protruding upward from the lid 6, the lower surface faces the surface of the lid 6, and the terminal surfaces 8 a 1 and 8 b 1 which are the upper surfaces are at the same height position as the lid 6. It has the structure which becomes parallel.

  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 can 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 toward the bottom surface along the wide surface of the battery can 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.

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 obtained by winding a positive electrode body 31 and a negative electrode body 32 in a flat shape with a separator 33 interposed therebetween, and a positive electrode mixture 31b and a negative electrode mixture are provided on both end surfaces in the winding axis direction. A positive foil exposed portion 31c and a negative foil exposed portion 32c that are not coated with 32b are provided. In the wound electrode body 3, the outermost electrode body is the negative electrode body 32, and the separator 33 is wound further outside. The end of the separator 33 is fixed to the outermost peripheral surface of the separator 33 with an adhesive tape (not shown), and the wound state is maintained. The winding end of the separator 33 is disposed at a substantially central position on one flat surface of the wound electrode body 3, and the central portion in the winding axis direction is fixed by an adhesive tape (not shown). The separator 33 has a role of insulating the positive electrode body 31 and the negative electrode body 32.

  The negative electrode mixture 32b of the negative electrode body 32 is larger in the width direction than the positive electrode mixture 31b of the positive electrode body 31, and thus, the positive electrode mixture 31b is configured to be sandwiched between the negative electrode mixture 32b without fail. The positive electrode body 31 is obtained by applying a positive electrode mixture 31b on both surfaces of a positive electrode foil 31a, and has an uncoated positive electrode foil exposed portion 31c on one side in the width direction of the positive electrode foil 31a. The negative electrode body 32 is obtained by applying a negative electrode mixture 32b on both surfaces of a negative electrode foil 32a, and has an uncoated negative electrode foil exposed portion 32c on the other side in the width direction of the negative electrode foil 32a. The positive electrode foil exposed portion 31c and the negative electrode foil exposed portion 32c are wound so as to be positioned 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 material of the separator 33 is a porous polyethylene resin. 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 an external perspective view of a prismatic secondary battery showing a state where a part of the pressure-sensitive adhesive sheet is developed, and FIG. 5 is a development view of the pressure-sensitive adhesive sheet.

  The pressure-sensitive adhesive sheet 13 is constituted by a single sheet member, and is attached so as to be wound around the bottom surface 21 and the side wall surface 22 of the battery can 1, and on the side wall surface 22, the lid 6 and the battery can 1 are attached. It is affixed so that the whole surrounding surface of the battery can 1 except a welding part may be covered.

  As shown in FIG. 5, the adhesive sheet 13 is formed by three rectangular sheet pieces 13A, 13B, and 13C. The sheet piece 13A has a size that covers almost the entire side wall surface 22 of the battery can 1 and faces the wide surface facing portions 13Aa and 13Ab facing the wide surfaces 22a and 22b and the narrow surfaces 22c and 22d. Narrow surface facing portions 13Ac, 13Ad, and 13Ae are provided. The wide surface facing portions 13 </ b> Aa and 13 </ b> Ab have a lateral width length W <b> 1 extending in the lateral width direction of the wide surfaces 22 a and 22 b of the battery can 1. The narrow surface facing portion 13Ac is disposed between the wide surface facing portions 13Aa and 13Ab. The narrow surface facing portions 13Ad and 13Ae are arranged at both ends in the longitudinal direction of the sheet piece 13A, that is, at positions spaced apart from each other with the wide surface facing portions 13Aa and 13Ab interposed therebetween, and the positive external terminal 8A. The side narrow surfaces 22c are overlapped with each other.

  The sheet pieces 13 </ b> B and 13 </ b> C have a size that covers the bottom surface 21 of the battery can 1. The overlap margin formed by the sheet pieces 13 </ b> B and 13 </ b> C is disposed and attached to the can bottom surface 21. The sheet piece 13B is continuously provided at the lower end of the wide surface facing portion 13Aa, and the sheet piece 13C is continuously provided at the lower end of the wide surface facing portion 13Ab.

  The sheet pieces 13B and 13C are sized so as to form a pair of can exposed portions 51 and 52 that expose portions of the battery can 1 at both ends in the longitudinal direction of the can bottom 21 when attached to the battery can 1. Have. Specifically, it has a width W2 that is shorter than the width W1 of the wide surface facing portions 13Aa and 13Ab of the sheet piece 13A. The sheet pieces 13B and 13C are arranged such that the end on the negative electrode external terminal 8B side is disposed at a position spaced apart from the narrow surface facing portion 13Ac by the lateral width length W3, and from the narrow surface facing portions 13Ad, 13Ae to the lateral width length W3. The end on the positive electrode external terminal 8A side is disposed at a position spaced apart by a longer lateral width W4 (W3 <W4).

  6A is an external perspective view showing an example of the prismatic secondary battery according to the present embodiment, and FIG. 6B is a bottom view showing the prismatic secondary battery of FIG. 6A from the bottom side of the can.

  As shown in FIGS. 6A and 6B, the square secondary battery C <b> 1 is attached such that the adhesive sheet 13 is wound around the side wall surface 22 and the can bottom surface 21 of the battery can 1. Although the timing which affixes the adhesive sheet 13 to the battery can 1 is after battery assembly, it may be before battery assembly.

  The pressure sensitive adhesive sheet 13 is provided with can exposed portions 51 and 52 that expose a part of the bottom surface 21 of the can. The can exposed portions 51 and 52 have an asymmetric shape with respect to a center line orthogonal to the long side of the can bottom 21. The can exposed portions 51 and 52 are provided at corners located on both longitudinal sides of the bottom surface 21 of the battery can 1. Specifically, one can exposed portion 51 is provided at a corner on the positive electrode external terminal 8 </ b> A side of the battery can 1, and the other can exposed portion 52 is a corner on the negative electrode external terminal 8 </ b> B side of the battery can 1. Provided in the department. As shown in FIGS. 6A and 6B, the can exposed portions 51 and 52 have a shape in which the can exposed portion 51 on the positive electrode external terminal 8A side is larger than the can exposed portion 52 on the negative electrode external terminal 8B side. doing. That is, the can exposed portion 51 exposes the can bottom 21 larger than the can exposed portion 52.

  These asymmetric can exposed portions 51 and 52 are marks indicating the arrangement of the positive external terminal 8A or the negative external terminal 8B, and are marks 50 indicating the polarity of the positive external terminal 8A or the negative external terminal 8B. The center line LC1 is set so as to extend in a direction orthogonal to the long side at the center position in the long side direction of the bottom surface 21 of the can.

  According to the prismatic secondary battery C1 according to the present embodiment, the positive and negative electrode sides of the prismatic secondary battery C1 are viewed from the can bottom 21 side by looking at the can exposed portions 51 and 52 that are the marks 50 on the bottom surface 21 of the can. Can be confirmed. Therefore, for example, even in a situation where only the bottom surface 21 of the prismatic secondary battery C1 is visible, it is possible to prevent the battery C1 from being erroneously disposed on the opposite side.

  Since the battery can 1 has an R-shaped chamfering process between the side wall surface 22 and the bottom surface 21 and between the wide surfaces 22a and 22b and the narrow surfaces 22c and 22d of the side wall surface 22, When the adhesive sheet 13 made of a single sheet member is attached to the battery can 1, it is difficult to attach the adhesive sheet 13 to the corners of the bottom surface 21 of the battery can 1 well. According to the above, since the exposed portions 51 and 52 are provided and exposed at the corners at both ends in the longitudinal direction of the bottom surface 21 of the can, the adhesive sheet 13 can be easily attached.

  Further, the lid 6 is provided with many components such as the positive electrode external terminal 8A, the negative electrode external terminal 8B, the gas discharge valve 10, the liquid injection port 9, and the liquid injection plug 11, and the vacant space is narrow and large. Although a mark cannot be provided, it is easy to provide a large mark on the bottom surface 21 of the can. Therefore, compared with the case where it is provided on the lid 6, it has a specific effect when it is provided on the bottom surface 21 of the can so that the mark can be easily recognized. Further, since the battery can 1 is a metal color of aluminum, the pressure-sensitive adhesive sheet 13 has a color different from the battery can 1, for example, a color such as green color. The presence and shape of 51 and 52 can be easily visually confirmed.

  Further, in this embodiment, the can exposed portion 51 provided on the positive electrode external terminal 8A side has a larger shape than the can exposed portion 52 provided on the negative electrode external terminal 8B side, so the negative electrode external terminal 8B. The positive electrode external terminal 8A side having higher resistance and higher heat generation temperature than the side can be exposed to a greater extent to improve heat dissipation, and the temperature rise of the entire battery C1 can be suppressed.

  In the present embodiment, the can exposed portion 51 at the corner of the battery can 1 on the positive electrode external terminal 8A side has a large shape, but the present invention is not limited to this, and the direction of the positive electrode side and the negative electrode side of the battery can be Any material having an asymmetric shape that can be discriminated from the bottom side may be used. In addition, the visual recognition method of the above-mentioned mark 50 is not limited to an operator's visual observation, The thing by visual devices, such as a camera, is also included.

  7 is an external perspective view of the assembled battery according to the present embodiment, FIG. 8 is a cross-sectional view taken along the line AA of FIG. 7, and FIG. 9 is a perspective view illustrating the assembled method of the assembled battery according to the present embodiment. FIG.

  The assembled battery C2 includes a plurality of rectangular secondary batteries C1 stacked and arranged in the battery thickness direction via spacers 70 between them, and is secured using a pair of end plates and a pair of side plates (not shown). Assembled by.

  The spacer 70 is made of, for example, an insulating synthetic resin material, and is interposed between a plurality of rectangular secondary batteries C1 so as to face the wide surfaces 22a and 22b (see FIG. 6B) of the side wall 22 71 and a pair of side plates that protrude in the direction away from each other along the arrangement direction from both ends in the width direction of the substrate portion 71 and face the narrow surfaces 22c and 22d (see FIG. 6B) of the side wall surface 22 of the rectangular secondary battery C1. Part 72 and a top plate part 73 that protrudes from the one side in the height direction of the substrate part 71 in the direction away from each other along the arrangement direction and faces the lid 6 of the prismatic secondary battery C1.

  The top plate part 73 is inserted with the positive external terminal 8A and the negative external terminal 8B of the square secondary battery C1 with the cover surface of the cover 6 of the square secondary battery C1 in contact with the inner surface of the top plate part 73. A notch is provided. As shown in FIG. 8, each spacer 70 holds the positive external terminal 8 </ b> A and the negative external terminal 8 </ b> B in a state of protruding from the top plate portion 73 by sandwiching the square secondary battery C <b> 1 therebetween.

  In the assembled battery C2, the substrate portion 71 of the spacer 70 is brought into contact with the wide surface of the rectangular secondary battery C1, and the side plate portion 72 of the spacer 70 is opposed to the narrow surface of the rectangular secondary battery C1 and pressed from both sides in the arrangement direction. Thus, the rectangular secondary battery C1 is held.

  As shown in FIG. 8, in the prismatic secondary battery C1, the positive external terminals 8A and the negative external terminals 8B are alternately arranged along the arrangement direction so as to be electrically connected in series with the adjacent square secondary batteries C1. Is done. And among the square secondary batteries C1 adjacent to each other, a bus bar is bridged between the positive electrode external terminal 8A of one square secondary battery C1 and the negative electrode external terminal 8B of the other square secondary battery C1. The terminal surfaces 8a1 and 8b1 are welded and connected in series in contact with the terminal surfaces 8a1 and 8b1. As shown in FIG. 7, the can bottom surface 21 of each square secondary battery C1 is exposed on one surface side of the assembled battery C2, which is a direction orthogonal to the arrangement direction of the square secondary batteries C1, for example, There is no cooling plate touched and cooled.

  As shown in FIG. 8, the assembled battery C2 including a plurality of prismatic secondary batteries C1 may be assembled with reference to the lid surface of the lid 6 of the prismatic secondary battery C1.

  The can bottom 21 can be considered as another reference plane. However, when the can bottom 21 is used as a reference, variations in the battery height direction of the terminal surfaces 8a1 and 8b1 are caused by variations in the dimensions of the battery can 1 and the lid 6. There is a possibility that the welding between the bus bar (not shown) for electrically connecting the rectangular secondary batteries C1 to the positive external terminal 8A and the negative external terminal 8B becomes unstable.

  On the other hand, the method of assembling the assembled battery C2 based on the lid surface of the lid 6 shown in FIG. 8 can suppress variations in the position of the terminal surfaces 8a1 and 8b1 in the battery height direction. 8A and the negative electrode external terminal 8B are stably welded.

  However, in the case of the method of assembling with the lid surface of the lid 6 as a reference, since the rectangular secondary battery C1 is incorporated with the lid surface down as shown in FIG. 9, the positive external terminal 8A and the negative external terminal 8B can be visually recognized. There is a possibility that the insertion direction of the positive external terminal 8A and the negative external terminal 8B is wrong.

  In response to such a problem, the prismatic secondary battery C1 according to the present embodiment is provided with a mark 50 indicating the arrangement and polarity of the positive electrode external terminal 8A and the negative electrode external terminal 8B on the outside of the can bottom surface 21. Since the outer can exposed portions 51 and 52 have an asymmetric shape with respect to the center line LC1 perpendicular to the long side of the can bottom 21, the polarity can be confirmed from the can bottom 21 side, and the positive side of the battery C1 And the direction of the negative electrode side can be easily confirmed. Therefore, the assembled battery C <b> 2 can be assembled without mistaking the external terminal insertion direction.

FIG. 10 is an exploded perspective view of a prismatic secondary battery for explaining another embodiment of the insulating layer.
In the rectangular secondary battery C <b> 1 of this example, an insulating layer is formed by a heat shrinkable sheet 14 instead of the adhesive sheet 13. The heat-shrinkable sheet 14 has a bag shape that is sized so that the battery can 1 can be easily inserted through the opening 14a. Exposed portions 51 and 52 are provided at positions corresponding to both longitudinal sides of the bottom surface 21 of the can. Opening holes 14b and 14c for forming are formed in advance. The opening hole 14b provided on the positive electrode external terminal 8A side is formed larger than the opening hole 14c provided on the negative electrode external terminal 8B side. For example, when the battery can 1 is a metal color, the heat-shrink sheet 14 has a color different from that of the battery can 1, for example, green. An insulating layer can be formed by covering the outside of the battery can 1 with the heat-shrinkable sheet 14 and heat-shrinking the can, and can exposed portions 51 and 52 as marks 50 on the bottom surface of the can (see FIGS. 6A and 6B). Can be provided.

  Therefore, by looking at the can exposed portions 51 and 52 that are the marks 50 provided on the can bottom surface 21, it is possible to confirm the directions of the positive electrode side and the negative electrode side of the rectangular secondary battery C1 from the can bottom surface 21 side. Therefore, for example, even in a situation where only the bottom surface 21 of the prismatic secondary battery C1 is visible, it is possible to prevent the battery from being erroneously disposed on the opposite side. According to the present embodiment, compared with the pressure-sensitive adhesive sheet 13, the battery can 1 can be easily provided with an insulating layer, and the manufacturing time can be shortened. In the above-described embodiment, the case where the can exposed portions 51 and 52 are provided on both the positive electrode external terminal 8A side and the negative electrode external terminal 8B side has been described as an example, but may be provided on only one of them.

  FIG. 11A is a perspective view of a prismatic secondary battery for explaining another embodiment of the can exposed portion, and FIG. 11B is a bottom view showing the prismatic secondary battery of FIG. 11A from the bottom face side of the can.

  In the square secondary battery C1 of the present embodiment, the can exposed portion 51 is provided only on the positive electrode external terminal 8A side by the adhesive sheet 13, and the can exposed portion is not provided on the negative electrode external terminal 8B side. Even in such a configuration, the orientation of the positive electrode side and the negative electrode side of the rectangular secondary battery C1 can be confirmed from the can bottom surface 21 side by looking at the can exposed portion 51. Further, according to the present embodiment, the exposed area where the battery can 1 is exposed can be made as small as possible, and the possibility of a short circuit due to contact with other prismatic secondary batteries C1 and the like can be reduced.

  12A and 12B are development views showing examples of the pressure-sensitive adhesive sheet forming the can exposed portion shown in FIG. 11A.

  12A, the sheet piece 13B and the sheet piece 13C are separated from each other by the same distance as the width of the narrow surface facing portion 13Ac. The entire corner on the negative electrode external terminal 8B side which is one side in the longitudinal direction of the can bottom 21 of the can 1 is covered.

  The pressure-sensitive adhesive sheet 13 shown in FIG. 12B is provided with a sheet piece 13D that protrudes from the lower end of the narrow surface facing portion 13Ac instead of the sheet pieces 13B and 13C. The sheet piece 13D has a size W5 that is affixed to the bottom surface 21 of the can and extends to a position near the corner of the bottom surface 21 on the positive electrode external terminal side to expose a part of the bottom surface 21 of the can (W5 <W1).

13A to 13C are bottom views of a prismatic secondary battery for explaining another embodiment of the can exposed portion.
The embodiment shown in FIG. 13A is characterized in that a can exposure portion 53 having a concave shape in plan view is provided instead of the can exposure portion 51 having a substantially rectangular shape in plan view. At the end of the sheet pieces 13B and 13C on the positive electrode external terminal 8A side, a convex portion 13E is provided. By sticking the adhesive sheet 13 to the battery can 1, the end of the can bottom surface 21 on the positive electrode external terminal 8A side The part is formed with a can exposed portion 53 having a concave shape in plan view. By making the shape of the can exposed portion 51 concave in a plan view, the exposed area of the can bottom portion 21 by the can exposed portion 51 can be reduced as much as possible, and the possibility of a short circuit due to contact with the battery can 1 is reduced. be able to.

  In the embodiment shown in FIGS. 13B and 13C, the can exposed portions 54 and 55 are provided not at the corners of the battery can 1 but at an intermediate position between the center line LC1 of the can bottom 21 and the end on the negative electrode external terminal 8B side. It has the characteristics in the point. The position where the can exposed portion is provided is not limited to the corner portion of the battery can 1, and the prismatic secondary battery C <b> 1 can be placed on the bottom surface of the can by providing the can exposed portion at a position displaced in the longitudinal direction from the center line LC <b> 1 of the can bottom surface 21. When viewed from the 21st side, the orientations of the positive electrode side and the negative electrode side of the battery can be recognized. The can exposing portion 54 has a substantially rectangular shape in a plan view in which the can bottom 21 is exposed across the thickness direction of the battery can 1. The can exposed portion 55 has a substantially circular shape in a plan view having a diameter smaller than the thickness of the battery can 1.

<Second Embodiment>
The second embodiment of the present invention will be described below.
14A is an external perspective view showing an example of the prismatic secondary battery according to the second embodiment, and FIG. 14B is a front view showing the bottom surface of the prismatic secondary battery of FIG. 14A. Note that the same components as those in the above-described embodiments are given the same reference numerals, and detailed description thereof is omitted.

  What is characteristic in the present embodiment is that the insulating layer on the outer surface of the battery can 1 is composed of an insulating coating provided by applying an insulating paint.

  As shown in FIGS. 14A and 14B, an insulating coating 15 is provided on the outer surface of the battery can 1. In the insulating coating film 15, can exposed portions 51 and 52 are provided outside the can bottom 21 of the battery can 1. The can exposed portions 51 and 52 have an asymmetric shape with respect to a center line LC1 orthogonal to the long side of the can bottom 21.

  Each of the can exposed portions 51 and 52 has a substantially rectangular shape in plan view. The can exposed portion 51 is provided on the positive electrode external terminal 8A side, the can exposed portion 52 is provided on the negative electrode external terminal 8B side, and the can exposed portion 51 is formed larger than the can exposed portion 52. .

  The can exposed portions 51 and 52 are marks indicating the arrangement of the positive external terminal 8A or the negative external terminal 8B, and are marks indicating the polarity of the positive external terminal 8A or the negative external terminal 8B. The can exposed portions 51 and 52 can be formed by masking the corresponding portions when the insulating coating film 15 is applied to the battery can 1.

  According to the prismatic secondary battery C1 according to the present embodiment, the positive electrode of the prismatic secondary battery C1 from the can bottom surface 21 side by looking at the can exposed portions 51 and 52 that are the marks 50 provided on the bottom surface 21 of the can. The direction of the side and the negative electrode side can be confirmed. Therefore, for example, even in a situation where only the bottom surface of the prismatic secondary battery C1 can be visually recognized, it is possible to prevent the battery from being erroneously disposed on the opposite side.

  And since the insulating layer is comprised by the insulating coating film 15, compared with 1st Embodiment which affixes the adhesive sheet 13 to the battery can 1, the operation | work for forming an insulating layer is easy, and it peels off It has the advantage of being difficult.

  In the present embodiment, the can exposed portion 51 at the corner of the battery can 1 on the positive electrode external terminal 8A side has a large shape, but the present invention is not limited to this, and the direction of the positive electrode side and the negative electrode side of the battery can be Any material having an asymmetric shape that can be discriminated from the bottom side may be used. In addition, the visual recognition method of the above-mentioned mark 50 is not limited to an operator's visual observation, The thing by visual devices, such as a camera, is also included.

  According to this embodiment, the battery can 1 can be attached with the mark 50 in the state of a single component, and can also be attached after the prismatic secondary battery C1 is assembled.

  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 prismatic secondary battery C2 assembled battery 1 battery can 100 opening 2 insulating protective film 3 wound electrode body 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 insulating 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 portion 12B Negative electrode connection portion 13 Adhesive sheet 14 Heat shrink sheet 15 Insulating coating 21 Can bottom surface 22 Side wall surface 31 Positive electrode body 31a Positive electrode Foil 31b Positive electrode mixture 31c Positive electrode foil exposed portion 32 Negative electrode body 32a Negative electrode foil 32b Negative electrode mixture 32c Negative electrode foil exposed portion 31d Positive foil connection portion 32d Negative foil connection portion 33 Separator 41A Positive current collector base portion 41B Negative current collector base portion 42A Positive electrode side connection end 42B Negative electrode side connection end 43A Positive electrode side opening hole 43B Negative electrode side opening hole 50 Marks 51 to 52 Can exposed portion 70 Spacer 71 Substrate portion 72 Side plate portion 73 Top plate portion

Claims (8)

A rectangular secondary battery having a rectangular battery can having a rectangular can bottom, a battery lid for sealing an opening facing the bottom of the battery can, and a positive external terminal and a negative external terminal provided on the battery cover A battery,
Having an insulating layer covering the outer surface of the battery can;
The insulating layer is provided with a can exposed portion that exposes a part of the bottom surface of the can,
The rectangular secondary battery, wherein the can exposed portion has an asymmetric shape with respect to a center line perpendicular to the long side of the bottom surface of the can.   The prismatic secondary battery according to claim 1, wherein the can exposed portion is a mark indicating an arrangement of the positive electrode or the negative electrode external terminal.   The prismatic secondary battery according to claim 1, wherein the can exposed portion is a mark indicating a polarity of the positive electrode or the negative electrode external terminal.   The prismatic secondary battery according to claim 1, wherein the insulating layer has a color different from an outer surface of the battery can.   The prismatic secondary battery according to claim 1, wherein the insulating layer is formed of an adhesive sheet.   The prismatic secondary battery according to claim 1, wherein the insulating layer is formed of a heat shrinkable sheet.   The can exposed portion is provided on each of the positive external terminal side and the negative external terminal side of the bottom surface of the can, and the positive external terminal side is larger than the negative external terminal side. Item 2. The prismatic secondary battery according to item 1. An assembled battery in which a plurality of prismatic secondary batteries are arranged,
The plurality of prismatic secondary batteries are:
A battery can having a rectangular bottom surface, a battery lid for sealing an opening facing the bottom surface of the battery can, a positive external terminal and a negative external terminal provided on the battery cover, and an outer surface of the battery can Having an insulating layer covering
The can bottoms are arranged in a state where the bottom surfaces of the cans are exposed on one surface side which is a direction orthogonal to the arrangement direction of the plurality of prismatic secondary batteries, and the can exposed portions are center lines perpendicular to the long sides of the bottom surfaces An assembled battery having an asymmetric shape with respect to

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