JP2009026655A - Flat type battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flat type battery wherein the wound condition of an electrode body is held with no looseness and there is no need to form a slit in the end of a positive electrode or in the end of a negative electrode for an anti-loosening tape to be arranged on the electrode body. <P>SOLUTION: The flat type battery comprises the electrode body 1 wound in a flat shape with a band-like separator 15 laid between the band-like positive electrode 12 and the band-like negative electrode 13, and a flat battery can 2 storing the electrode body 1. The battery can 2 consists of a positive electrode can 6 for connecting an end 12a on the outermost periphery side of the positive electrode 12 in the wound condition to the inner face, a negative electrode can 10 for connecting an end 13a on the outermost periphery side of the negative electrode 13 in the wound condition to the inner face, and a gasket 11 arranged between the peripheral edges of the positive electrode can 6 and the negative electrode can 10 for sealing between the positive electrode can 6 and the negative electrode can 10. In attitude along a direction perpendicular to the winding direction of the electrode body 1, the wound-shape holding winding tape 22 is mounted between a pair of flat faces 1a, 1b formed on the outermost periphery of the electrode body 1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a flat battery such as a lithium ion secondary battery in which an electrode body as a power generation element is accommodated in a battery can.

  As a known example of this type of flat battery, for example, Patent Document 1 can be cited. In this flat battery, an electrode body is formed by spirally winding a strip-shaped separator between a strip-shaped positive electrode and a strip-shaped negative electrode, and the electrode body is formed with a positive electrode can, a negative electrode can, and a gasket. In a battery can. In addition, by winding the tape in the winding direction of the electrode body on the outer peripheral surface of the electrode body, the wound state of the electrode body is maintained and the electrode body is not loosened.

Japanese Patent Laying-Open No. 2005-32671 (FIG. 1)

  However, in Patent Document 1, in order to wind the tape in the winding direction of the electrode body, the slit extending in the winding direction at the end of the positive electrode welded to the inner surface of the positive electrode can or the end of the negative electrode welded to the inner surface of the negative electrode can It is necessary to form each notch. For this reason, it is necessary to divide the edge part of a positive electrode and the edge part of a negative electrode into two in the width direction (refer FIG. 1 of patent document 1), and each edge part of the positive electrode divided | segmented into two and the edge part of a negative electrode Each time, the time and labor for welding the positive electrode can and the negative electrode can separately arise, and the assembly of the battery is complicated accordingly.

  The present invention has been made in order to solve the above-described problems. In order to keep the wound state of the electrode body from being loosened, and to dispose the tape used for preventing the loosening to the electrode body. An object of the present invention is to provide a flat battery that does not require a slit or the like to be formed at the end of the positive electrode or the end of the negative electrode.

  As shown in FIGS. 1 and 2, the flat battery according to the present invention is an electrode body wound in a flat shape with a strip-shaped separator 15 interposed between the strip-shaped positive electrode 12 and the strip-shaped negative electrode 13. 1 and a flat battery can 2 that accommodates the electrode body 1, and the battery can 2 has a positive electrode can 6 that connects an outermost end 12 a of the wound positive electrode 12 to the inner surface, and a winding The negative electrode can 10 is connected to the inner periphery of the outermost peripheral end 13a of the negative electrode 13, and the positive electrode can 6 and the negative electrode can 10 are sealed between the positive electrode can 6 and the negative electrode can 10. A flat battery including a gasket 11 that extends between a pair of flat surfaces 1a and 1b formed on the outermost periphery of the electrode body 1 in a posture along a direction orthogonal to the winding direction of the electrode body 1. The tape 22 for holding the winding shape is attached. Here, the tape 22 is preferably excellent in insulation, chemical resistance, and the like, and includes tapes that are permeable to ions and those that are not permeable. The width dimension in the winding direction of the electrode body 1 of the tape 22 is preferably small, and the width dimension is determined according to the strength of the tape 22 and the like.

  Specifically, the tape 22 is formed of a material that is difficult to stretch, and at least both ends 22a and 22b of the tape 22 are formed on the flat surfaces 1a and 1b of the electrode body 1 as shown in FIG. Each is fixed to the electrode body 1 by adhesion or the like. The tape 22 may be an adhesive tape (adhesive tape) or the like, or a part of the tape 22 may be fixed to the side surface of the electrode body 1.

  In addition, as shown in FIG. 6, the tape 22 is attached to the electrode body 1 by being wound around the electrode body 1 in a circular shape along a direction orthogonal to the winding direction of the electrode body 1. it can. Here, the tape 22 may be formed of a ring-shaped synthetic rubber or the like that can expand and contract. In this case, the tape 22 is attached to the electrode body 1 by contraction of the tape 22 after being externally fitted to the electrode body 1 with the tape 22 stretched. A part or all of the tape 22 may be fixed to the electrode body 1. Here, the tape 22 may be formed of an inextensible material.

  As shown in FIGS. 1 and 6, the tape 22 is preferably disposed at the end of the electrode body 1 in the winding direction on the flat surfaces 1 a and 1 b of the electrode body 1.

  The separator 15 includes a first separator 15 a wound so as to cover the outer side of the positive electrode 12, and a second separator 15 b wound so as to cover the outer side of the negative electrode 13. The portion 12a protrudes more outward in the winding direction than the outermost end in the winding direction of the first separator 15a, and the outermost end in the winding direction of the first separator 15a is fixed to the negative electrode 13. The outermost peripheral end 13a of the second separator 15b protrudes outward in the winding direction from the outermost peripheral end in the winding direction of the second separator 15b, and the outermost peripheral end of the second separator 15b in the winding direction. Can be fixed. The first separator 15a and the second separator 15b may be integrated by connecting the inner peripheral end of the first separator 15a in the winding direction and the inner peripheral end of the second separator 15b in the winding direction. The separator 15a and the second separator 15b may be separate. The first separator 15a and the end portion 12a of the positive electrode 12, and the second separator 15b and the end portion 12a of the positive electrode 12 are fixed by an adhesive tape, an adhesive, or the like.

  In the flat battery of the present invention, both flat surfaces of the electrode body 1 in a posture along the direction perpendicular to the winding direction of the electrode body 1 (hereinafter referred to as the orthogonal direction) of the tape 22 for holding the wound shape. 1a and 1b are attached so that the tape 22 swells so that the space between the flat surfaces 1a and 1b of the electrode body 1 is expanded by the tape 22, and the flat surfaces 1a and 1b of the electrode body 1 are loosened. It is suppressed that the gap is shifted and loosened in the winding direction of the electrode body 1, and the appropriate winding state of the electrode body 1 can be reliably maintained. In addition, when the tape 22 is attached in the orthogonal direction, a slit for passing the tape through the end portion 12a of the positive electrode 12 and the end portion 13a of the negative electrode 13 which are necessary in Patent Document 1 becomes unnecessary, and thus the positive electrode 12 divided by the slit is used. This eliminates the trouble of welding the positive electrode can 6 and the negative electrode can 10 for each of the end portions 12a and the end portion 13a of the negative electrode 13, respectively. As a result, it is possible to prevent the assembly work from being complicated and to contribute to the reduction of the manufacturing cost of the battery.

  Further, when the tape 22 is attached in the orthogonal direction, the winding state of the electrode body 1 can be reliably maintained even when the width dimension of the tape 22 (width dimension in the winding direction of the electrode body 1) is reduced. . This means that the area of the tape 22 that can be interposed between the positive electrode active material layer 16 formed on the inner surface or the outer surface of the positive electrode 12 and the negative electrode active material layer 19 formed on the inner surface or the outer surface of the negative electrode 13 can be minimized. Therefore, the active material layers 16 and 19 can be effectively used to contribute to improvement of battery characteristics (higher capacity and higher output).

  If the tape 22 is made of a material that is difficult to stretch, and its both end portions 22a and 22b are fixed to the flat surfaces 1a and 1b of the electrode body 1, the electrode body 1 will swell and the electrode body 1 will loosen. Therefore, the proper winding state of the electrode body 1 can be reliably maintained. In addition, the length of the tape 22 can be made shorter than when the electrode body 1 is wound around the electrode body 1 along a direction orthogonal to the winding direction of the electrode body 1, and the amount of the tape 22 used can be suppressed.

  When the tape 22 is wound around the electrode body 1 along a direction orthogonal to the winding direction of the electrode body 1, the winding tape 22 is firmly attached to the electrode body 1, and the winding tape 22 This more reliably prevents the wound electrode body 1 from being loosened. Moreover, even if the tape 22 is not fixed to the electrode body 1, the tape 22 can be attached to the electrode body 1, and the labor for assembling the battery can be reduced accordingly.

  When the tape 22 is arranged at the end in the winding direction of the electrode body 1 in the flat planes 1a and 1b, the active material layers 16 and 19 of the positive electrode 12 and the negative electrode 13 are wound in the winding direction of the electrode body 1 in the flat planes 1a and 1b. The battery capacity can be increased by this amount.

  When the end in the winding direction of the first separator 15a is fixed to the end portion 12a of the positive electrode 12, and the end in the winding direction of the second separator 15b is fixed to the end portion 13a of the negative electrode 13, the first separator 15a becomes the positive electrode. 12 and the second separator 15b are prevented from leaving the negative electrode 13. As a result, the separators 15a and 15b interposed between the positive electrode 12 and the negative electrode 13 are displaced and the positive electrode 12 and the negative electrode 13 are reliably prevented from coming into contact with each other, and the positive electrode 12 and the negative electrode 13 are short-circuited. It is surely prevented.

First Embodiment FIGS. 1 to 5 show a first embodiment of a flat battery according to the present invention. This flat battery accommodates an electrode body 1 and a non-aqueous electrolyte as a power generation element in a battery can 2. As shown in FIGS. 3 and 4, the battery can 2 includes a positive electrode can 6 made of stainless steel that is bent vertically from the periphery of the square bottom wall 3 toward the upper side and the periphery of the upper wall 7 of the square. A stainless steel negative electrode can 10 bent vertically with the peripheral wall 9 facing downward, and a gasket 11 disposed between the peripheral edges of the positive electrode can 6 and the negative electrode can 10 to seal between the positive electrode can 6 and the negative electrode can 10. With. The lower part of the peripheral wall 9 of the negative electrode can 10 is processed into an inner and outer double helical fold.

  Then, the negative electrode can 10 and the gasket 11 are fitted into the positive electrode can 6, and the upper end portion of the peripheral wall 5 of the positive electrode can 6 is caulked to the inside so that the positive electrode can 3 and the negative electrode can 10 can form the gasket 11. Sealed and fixed in an interposed state.

  As shown in FIGS. 1 and 2, the electrode body 1 is wound in a spiral shape with a strip-shaped separator 15 interposed between a strip-shaped positive electrode 12 and a strip-shaped negative electrode 13 and has a thickness in the vertical direction. It is produced in a flat shape whose dimensions are smaller than the front and rear, left and right dimensions. The separator 15 includes a first separator 15 a wound so as to cover the outer side of the positive electrode 12, and a second separator 15 b wound so as to cover the outer side of the negative electrode 13, and is positioned on the outermost periphery of the electrode body 1. It is wound to do. The inner peripheral end in the winding direction of the first separator 15a and the inner peripheral end in the winding direction of the second separator 15b are connected, and the first separator 15a and the second separator 15b are integrated. The first separator 15a and the second separator 15b may be separate.

  In the positive electrode 12, a positive electrode active material layer 16 containing a positive electrode active material such as lithium cobaltate is formed on both inner and outer surfaces of a strip-like positive electrode current collector 17 made of aluminum foil. In the end portion 12a on the outermost peripheral side in the winding direction of the positive electrode 12, the positive electrode active material layer 16 is not formed on both the inner and outer surfaces of the positive electrode current collector 17, and the positive electrode current collector 17 is exposed. The tip end side of the end portion 12a on the outermost peripheral side of the positive electrode 12 protrudes outward in the winding direction from the end on the outermost peripheral side in the winding direction of the first separator 15a. The positive electrode current collector 17 at the end 12 a of the positive electrode 12 is welded (connected) to the inner surface of the bottom wall 3 of the positive electrode can 6 with ultrasonic waves or the like. The positive electrode current collector 17 at the end 12 a may be connected to the inner surface of the bottom wall 3 of the positive electrode can 6.

  In the negative electrode 13, a negative electrode active material layer 19 containing a negative electrode active material such as graphite is formed on both inner and outer surfaces of a strip-shaped negative electrode current collector 20 made of copper foil. In the end portion 13a on the outermost peripheral side of the winding in the negative electrode 13, the negative electrode active material layer 19 is not formed on both the inner and outer surfaces of the negative electrode current collector 20, and the negative electrode current collector 20 is exposed. The tip end side of the end portion 13a on the outermost peripheral side of the negative electrode 13 protrudes outward in the winding direction from the end on the outermost peripheral side in the winding direction of the second separator 15b. The negative electrode current collector 20 at the end portion 13 a of the negative electrode 13 is welded (connected) to the inner surface of the upper wall 7 of the negative electrode can 10 with ultrasonic waves or the like. Note that the negative electrode current collector 20 at the end 13 a may be connected to the inner surface of the upper wall 7 of the negative electrode can 10. In order to ensure that the negative electrode active material layer 19 faces the positive electrode active material layer 16, the width dimension of the negative electrode active material layer 19 is larger than the width dimension of the positive electrode active material layer 16 and the outermost negative electrode 13. As shown in FIG. 2, the negative electrode active material layers 19 and 19 on both the inner and outer surfaces extend to the outer peripheral side than the positive electrode active material layers 16 and 16 facing each other.

The separator 15 is made of a microporous thin film made of polyethylene having excellent insulating properties, and is capable of transmitting lithium ions and the like. The width dimension of the separator 15 is larger than the width dimension of the positive electrode active material layer 16 and the negative electrode active material layer 19. On the outer surface of the outermost peripheral end 12a of the positive electrode 12, the outermost peripheral end in the winding direction of the first separator 15a is a fixing tape 21 made of polypropylene, polyimide or the like having excellent insulation and chemical resistance. Pasted and fixed. Similarly, the outermost peripheral end in the winding direction of the second separator 15b is adhered and fixed to the outer surface of the outermost peripheral end 13a of the negative electrode 13 with the fixing tape 21. The non-aqueous electrolyte was prepared, for example, by dissolving LiPF ₆ in a solvent obtained by mixing ethylene carbonate and methyl ethyl carbonate.

  As shown in FIG. 1, in a pair of flat surfaces 1 a and 1 b formed above and below the outermost periphery of the electrode body 1, the winding direction of the electrode body 1 is defined at one end of the winding direction of the electrode body 1. A winding tape 22 for holding the winding shape is attached between the flat surfaces 1a and 1b of the electrode body 1 in a posture along the orthogonal direction (vertical direction in FIG. 2). That is, the winding tape 22 is disposed on the end portion on the side farther from the end portion 12 a of the positive electrode 12. In addition, separators 15a and 15b are arranged on both flat surfaces 1a and 1b. The upper and lower end portions 22a and 22b of the winding tape 22 are bent to the electrode body 1 side, and the both end portions 22a and 22b are attached to the flat surfaces 1a and 1b of the electrode body 1 and fixed. . The winding tape 22 is made of polypropylene, polyimide, or the like that is excellent in insulation, chemical resistance, and the like and is difficult to stretch. The winding tape 22 may be fixed to the flat surfaces 1a and 1b and the side surfaces of the electrode body 1, or may be fixed only to the flat surfaces 1a and 1b.

  The assembly of the battery will be described with reference to FIG. First, the winding tape 22 is attached to the outermost flat surfaces 1 a and 1 b of the wound electrode body 1. And with respect to the negative electrode can 10 which attached the gasket 11 to the opening edge part, the edge part 13a of the negative electrode 13 of the electrode body 1 is welded to the inner surface of the upper wall 7 of the negative electrode can 10 with an ultrasonic wave etc. Next, with the positive electrode can 6 in a vertical posture, the end 12 a of the positive electrode 12 of the electrode body 1 is welded to the inner surface of the bottom wall 3 of the positive electrode can 6 with ultrasonic waves or the like. Next, the non-aqueous electrolyte is injected into the negative electrode can 10 with the upper wall 7 of the negative electrode can 10 on the lower side and the positive electrode can 6 raised in the vertical posture accordingly. Thereafter, the positive electrode can 6 is placed on the negative electrode can 6, the negative electrode can 6 and the gasket 11 are fitted into the positive electrode can 6, and the opening end of the peripheral wall 5 of the positive electrode can 6 is caulked to the inside. As a result, the positive electrode can 6 and the negative electrode can 10 are caulked and fixed with the gasket 11 interposed therebetween, and the assembly of the battery is completed.

  Thus, since both ends 22a and 22b of the winding tape 22 are respectively fixed to both ends 22a and 22b of the electrode body 1, the winding electrode body 1 is prevented from being loosened by the winding tape 22. . From the viewpoint of battery capacity, the active material layers 16 and 19 are preferably formed to the vicinity of the ends on the outer peripheral side of the negative electrode 13 and the positive electrode 12, while the upper and lower end portions 22 a and 22 b of the winding tape 22 are positive electrode actives of the positive electrode 12. When entering between the material layer 16 and the negative electrode active material layer 19 of the negative electrode 13 facing the positive electrode active material layer 16, the movement of lithium ions and the like between the negative electrode 13 and the positive electrode 12 is hindered. As described above, the winding tape 22 is preferably disposed at the end of the electrode body 1 on the side farther from the end 12a of the positive electrode 12.

Second Embodiment FIG. 6 shows a second embodiment of a flat battery according to the present invention. In the second embodiment, the winding tape 22 for holding the winding shape has one end on the flat surface 1a, 1b of the electrode body 1 on the side farther from the end 12a of the positive electrode 12 in the winding direction of the electrode body 1. The electrode body 1 is wound around the electrode body 1 in a circumferential direction along a direction orthogonal to the winding direction of the electrode body 1 and attached to the electrode body 1 ( Attach). Since other points are the same as those of the first embodiment, description thereof is omitted.

  In the second embodiment, the winding tape 22 is securely attached to the electrode body 1, and the winding tape 22 can more reliably prevent the wound electrode body 1 from being loosened. The winding tape 22 of the second embodiment may be formed of a ring-shaped elastic rubber that can be expanded and contracted. In this case, the winding tape 22 is attached to the electrode body 1 by contraction of the winding tape 22 after the winding tape 22 is externally fitted to the electrode body 1 in a stretched state. That is, it is not necessary to attach the winding tape 22 to the electrode body 1, and the labor for assembling the battery is reduced by this amount.

1 is a perspective view of a first embodiment of a flat battery according to the present invention. It is a longitudinal cross-sectional view of the electrode body which concerns on this invention. It is a top view of a flat battery. It is a top view of a flat battery. It is a longitudinal cross-sectional view for demonstrating the assembly of a flat battery. It is a perspective view of 2nd Embodiment of the flat battery which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrode body 1a * 1b Flat surface 2 Battery can 6 Positive electrode can 10 Negative electrode can 11 Gasket 12 Positive electrode 12a End part 13 Negative electrode 13a End part 15 Separator 15a 1st separator 15b 1st separator 22 Winding tape

Claims (5)

An electrode body wound in a flat shape with a band-shaped separator interposed between a band-shaped positive electrode and a band-shaped negative electrode, and a flat battery can that accommodates the electrode body, the battery can A positive electrode can connecting an outermost peripheral end of the wound positive electrode to an inner surface; a negative electrode can connecting an outermost peripheral end of the wound negative electrode to an inner surface; and the positive electrode can A flat battery comprising a gasket arranged between the periphery of the negative electrode can and sealing between the positive electrode can and the negative electrode can,
A flat shape is characterized in that a winding shape holding tape is attached across a pair of flat surfaces formed on the outermost periphery of the electrode body in a posture along a direction orthogonal to the winding direction of the electrode body. Type battery.   The flat tape according to claim 1, wherein the tape is formed of an inextensible material, and is attached to the electrode body by fixing at least both ends of the tape to both flat surfaces of the electrode body. Type battery.   The flat battery according to claim 1, wherein the tape is attached to the electrode body by being wound around the electrode body along a direction orthogonal to a winding direction of the electrode body.   The flat battery according to any one of claims 1 to 3, wherein the tape is disposed on an end portion in a winding direction of the electrode body on the flat surface. The separator includes a first separator wound so as to cover the outside of the positive electrode, and a second separator wound so as to cover the outside of the negative electrode,
The outermost peripheral end of the positive electrode protrudes more outward in the winding direction than the outermost end in the winding direction of the first separator, and is on the outermost peripheral side in the winding direction of the first separator. An end is fixed, and an outermost end portion of the negative electrode protrudes more outward in the winding direction than an outermost end in the winding direction of the second separator, and the winding direction of the second separator The flat battery according to any one of claims 1 to 4, wherein an end on the outermost peripheral side is fixed.

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