JP2011187171A - Sealed battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealed battery advantageous for internal short circuit prevention upon receiving external force. <P>SOLUTION: In the sealed battery 1 with an opening of a square exterior can 2 sealed with a sealing body 4, a cleavage vent 30 and a liquid injection hole 20 are arranged in a length direction of the sealing body 4 so as to interpose a negative electrode terminal 9 between them, an electrode body with a negative electrode collector lead and a positive electrode collector lead led out is built in the exterior can 2, and the negative electrode collector lead is placed further toward a cleavage vent 30 side than the positive electrode collector lead. When a compression load F is added to the exterior can 2 so as to compress the exterior can 2 in the length direction of the sealing body 4, a cross-section shape of the sealing body 4 is formed so that bending at a position further toward the liquid injection hole 20 side with respect to the negative electrode 9 as a fulcrum occurs before the bending at a position further toward a cleavage vent 30 side with respect to the negative electrode 9 as a fulcrum. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a sealed battery in which an opening of a rectangular outer can is sealed with a sealing body.

  In recent years, small and light electronic devices such as mobile phones and mobile devices have become widespread. As a battery used in these electronic devices, a rectangular sealed battery is known (see, for example, Patent Document 1 below). A sealed battery is obtained by sealing the opening of a bottomed cylindrical outer can containing an electrode body with a sealing body.

  When the negative electrode terminal is provided on the sealing body via an insulating material, the negative electrode current collecting lead led out from the electrode body is joined to the lead body connected to the negative electrode terminal, and the positive electrode current collecting lead led out from the electrode body is connected to the sealing body It will be joined directly. In this configuration, the negative electrode terminal is charged to the negative electrode potential, and the sealing body and the outer can are charged to the positive electrode potential. In this case, a metal plate can be joined to the sealing body and used as the positive electrode terminal.

JP 2007-317577 A

  However, prismatic sealed batteries are becoming thinner and have a higher capacity, and accordingly, the thickness of the outer can tends to be reduced. In this case, damage due to buckling is easily caused when an external force is applied to the sealed battery. Damage due to buckling is likely to occur at a portion where stress concentration occurs or a portion where rigidity is weak, and in the sealed battery as described above, it is likely to occur at a portion of the cleavage vent provided on the surface of the sealing body.

  If the cleavage vent is placed near the negative electrode current collector lead led out from the electrode body, the negative electrode current collector lead led out from the electrode body contacts the inner wall of the outer can charged to the positive electrode potential due to deformation of the cleavage vent part. It becomes easy to do. When such a contact occurs, there is a possibility of smoking and ignition due to an internal short circuit. For this reason, if the high capacity thinning of the sealed battery proceeds, the possibility of such an internal short circuit also increases. Internal short circuit prevention can be achieved by adding an insulating tape or applying an insulating material, but this is disadvantageous in terms of cost.

  The present invention solves the above-described problems, and an object thereof is to provide a sealed battery that is advantageous for preventing an internal short circuit when an external force is applied.

  In order to achieve the above object, a sealed battery of the present invention is a sealed battery in which an opening of a rectangular outer can is sealed with a sealing body, and in the longitudinal direction of the sealing body, a cleavage bend, a liquid injection hole, However, the electrode body from which the negative electrode current collecting lead and the positive and negative current collecting leads are led out is built in the outer can, and the negative electrode current collecting lead is connected to the positive and negative current collecting terminals. When the compressive load is applied to the outer can so that the outer can is compressed in the longitudinal direction of the sealing body, and the outer can is compressed with respect to the negative electrode terminal. The sealing body is characterized in that the cross-sectional shape of the sealing body is formed so that the curve with the position as a fulcrum occurs before the curve with the position on the cleavage bend side as a fulcrum with respect to the negative electrode terminal.

  According to the sealed battery of the present invention, it is advantageous for preventing an internal short circuit when receiving an external force.

The perspective view which shows a mode that the sealing body 4 is fitted to the opening 3 of the armored can 2 in the sealed battery 1 which concerns on one embodiment of this invention. (A) The figure is a top view of the single-piece | unit state of the sealing body 4 which concerns on one embodiment of this invention, (b) A figure is sectional drawing in the AA line of (a) figure. The perspective view which shows the state which joined the sealing body 4 to the armored can 2 in the sealed battery 1 which concerns on one embodiment of this invention. The perspective view of the completion state of the sealed battery 1 which concerns on one embodiment of this invention. (A) The figure is sectional drawing in the BB line of FIG. 4, (b) is sectional drawing of the part corresponded to the A section of (a) figure in the sealing body 104 of the sealed battery which concerns on a comparative example. The figure which showed the state which made the sealed battery 1 which concerns on one embodiment of this invention stand upright. (A) The figure which showed the state which the sealed battery 1 which concerns on one embodiment of this invention curved, (b) The figure which showed the state where the sealed battery 100 concerning a comparative example curved. (A) The figure showed another example of the cross-sectional shape of the cleavage vent which concerns on one embodiment of this invention, (b) The figure shows another cross-sectional shape of the injection hole which concerns on one embodiment of this invention The figure which showed an example.

  According to the sealed battery of the present invention, when a compressive load is applied to the outer can so as to compress the outer can in the longitudinal direction of the sealing body, the negative electrode current collector derived from the electrode body inside the sealed battery The lead can be prevented from coming into contact with the outer can, and smoke and ignition due to an internal short circuit of the sealed battery can be prevented. Further, in order to prevent an internal short circuit, it is unnecessary to add an insulating tape or apply an insulating material, which is advantageous in terms of cost.

  In the sealed battery of the present invention, the sealing body has a cross-sectional shape formed so that a stress due to stress concentration is larger in a portion where the injection hole is formed than in a portion where the cleavage bend is formed. preferable. According to this structure, it becomes advantageous by prevention of an internal short circuit by the contact of the negative electrode current collecting lead to the outer can.

  Moreover, it is preferable that the cross-sectional shape of the said sealing body is formed so that the formation part of the said injection hole may become lower in rigidity than the formation part of the said cleavage bend. This configuration is also advantageous for preventing an internal short circuit due to contact of the negative electrode current collector lead with the outer can.

  Moreover, it is preferable that the said liquid injection hole contains the insertion part in which the convex part which seals the said liquid injection hole is inserted, and the enlarged diameter part larger diameter than the said insertion part. According to this configuration, when a compressive load is applied with a simple structure, it is possible to easily generate a curve with the position on the liquid injection hole side as a fulcrum with respect to the negative electrode terminal.

  Moreover, it is preferable that a recess or a groove is formed separately from the liquid injection hole on the liquid injection hole side with respect to the negative electrode terminal in the sealing body. Also with this configuration, when a compressive load is applied, it is possible to easily generate a curve with the position on the liquid injection hole side as a fulcrum with respect to the negative electrode terminal when a compressive load is applied.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing how the sealing body 4 is fitted into the opening 3 of the outer can 2 in the sealed battery 1 according to the present embodiment.

  The sealed battery 1 is, for example, a rectangular lithium ion battery, and is used for a mobile phone, a mobile device, or the like. The outer can 2 has a rectangular shape and is a bottomed cylindrical body in which a substantially rectangular opening 3 is formed at the upper end. The outer can 2 is formed, for example, by deep drawing a thin plate of aluminum or aluminum alloy.

  A flat electrode body 5 is built in the outer can 2. The electrode body 5 is produced by winding a positive electrode current collector and a negative electrode current collector in a spiral shape with a band-shaped separator interposed between the band-shaped positive electrode current collector and the band-shaped negative electrode current collector. It is a thing. A thin plate-like negative electrode current collecting lead 6 is led out from the negative electrode current collector, and a thin plate-like positive electrode current collecting lead 7 is led out from the positive electrode current collector.

  The sealing body 4 is a horizontally long member obtained by press-molding a thin plate of aluminum or an aluminum alloy, for example. A negative electrode terminal 9 (FIG. 3) is provided on the surface of the sealing body 4. In addition, a liquid injection hole 20 and a cleavage vent 30 are formed in the sealing body 4. The liquid injection hole 20 is a hole for injecting the electrolytic solution into the outer can 2. The cleavage vent 30 is for cleaving and releasing the battery internal pressure when the battery internal pressure abnormally increases. The cleavage vent 30 includes a recess 31 on the back surface side of the sealing body 4 and a recess 32 on the front surface side (FIG. 2B).

  A lead body 8 connected to the negative electrode terminal 9 (FIG. 3) is provided on the back surface of the sealing body 4. The lead body 8 has a convex portion 10 integral with the negative electrode terminal 9 passing therethrough. An insulating plate 16 is interposed between the lead body 8 and the back surface of the sealing body 4. The lead body 8 is joined to the negative electrode current collecting lead 6. As a result, the negative terminal 9 (FIG. 3) is charged to a negative potential. Details of the attachment structure of the negative electrode terminal 9 (FIG. 3) will be described later with reference to FIG.

  A positive electrode current collecting lead 7 is directly joined to the sealing body 4. As a result, the sealing body 4 and the outer can 2 to which the sealing body 4 is joined are charged to the positive electrode potential.

  FIG. 2A shows a plan view of the sealing body 4 in a single state before the negative electrode terminal 9 (FIG. 3) is attached. FIG. 2B is a cross-sectional view taken along the line AA in FIG. As shown in FIG. 2A, the liquid injection hole 20 and the cleavage vent 30 are formed so as to sandwich the attachment hole 13 of the negative electrode terminal.

  In FIG. 2 (b), the liquid injection hole 20 is composed of an insertion portion 21 and an enlarged diameter portion 22. The insertion part 21 is a part into which the convex part 14 integrated with the sealing body 11 shown in FIG. 3 is inserted. The diameter of the enlarged diameter portion 22 is larger than the diameter of the insertion portion 21. This is to reduce the rigidity of the sealing body 4 at the position of the liquid injection hole 20. Details of this will be described later with reference to FIGS.

  FIG. 3 is a perspective view showing a state in which the sealing body 4 is joined to the outer can 2. In the state of FIG. 3, the outer periphery of the sealing body 4 is fitted to the inner peripheral surface of the opening 3 of the outer can 2 while the negative electrode current collecting lead 6 and the positive electrode current collecting lead 7 are bent from the state of FIG. 1. . Further, in FIG. 3, the sealing body 4 is joined by seam welding in a state of being fitted to the inner peripheral surface of the opening 3 (FIG. 1) of the outer can 2.

  FIG. 3 shows the sealing body 11 before being attached to the liquid injection hole 20. After the nonaqueous electrolytic solution is injected into the outer can 2 from the liquid injection hole 20, the liquid injection hole 20 is closed with the sealing body 11. The sealing body 11 is formed by pressure bonding and laminating an aluminum plate 12 formed of aluminum or an aluminum alloy and a nickel plate 13 formed of nickel or a nickel alloy. The aluminum plate 12 is integrally formed with a convex portion 14 that is inserted into the insertion portion 21 of the liquid injection hole 20. The nickel plate 13 can be used as a positive terminal.

  FIG. 4 shows a perspective view of the sealed battery 1 in a completed state. In the state of this figure, the liquid injection hole 20 in FIG. 3 is closed by the sealing body 11. The sealing body 11 is joined to the sealing body 4 by welding the outer peripheral portion of the aluminum plate 12 to the sealing body 4.

  Both the sealing body 4 and the aluminum plate 12 are formed of the same kind of aluminum or aluminum alloy. For this reason, the weldability of both members is good. Further, the nickel plate 13 has good weldability between the nickel plate 13 and the lead plate of the same kind of metal.

  FIG. 5A shows a cross-sectional view taken along the line BB in FIG. In FIG. 5A, illustration of the outer can 2, the negative electrode current collector lead 6, and the positive electrode current collector lead 7 is omitted. The negative electrode terminal 9 is integrally formed with a convex portion 10, and the convex portion 10 penetrates the insulating packing 15, the insulating plate 16 and the lead body 8. The convex portion 10 and the lead body 8 are electrically connected, and the negative electrode current collecting lead 6 is joined to the lead body 8 as shown in FIG. As a result, the negative terminal 9 integrated with the convex portion 10 is charged to a negative potential. An insulating packing 15 is interposed between the negative electrode terminal 9 and the sealing body 4, and an insulating plate 16 is interposed between the lead body 8 and the sealing body 4. Thus, the negative electrode terminal 9 and the lead body 8 charged to the negative electrode potential are insulated from the sealing body 4 charged to the positive electrode potential by joining the positive electrode current collecting lead 7.

  The convex portion 14 of the sealing body 11 is inserted into the insertion portion 21 of the liquid injection hole 20. As described above, since the outer peripheral portion of the aluminum plate 12 of the sealing body 11 is welded to the sealing body 4, the sealing body 11 is charged to the same positive potential as the sealing body 4. For this reason, the nickel plate 13 can be used as a positive electrode terminal.

  FIG. 5B shows a cross-sectional view of a portion corresponding to part C of FIG. 5A in the sealing body 104 of the sealed battery according to the comparative example. As shown in FIG. 5 (b), the sealing body 104 according to the comparative example only forms an insertion portion (through hole) 121 having the same diameter between the front surface and the back surface of the sealing body 104, The enlarged diameter portion 22 as shown in FIG. 5A is not formed. Except for this point, the sealed battery according to the comparative example has the same specifications as the sealed battery 1 according to the present embodiment. Differences in effects between the sealed battery 1 according to the present embodiment and the sealed battery according to the comparative example will be described later with reference to FIGS. 7 (a) and 7 (b).

  FIG. 6 shows a state in which the sealed battery 1 is upright. In this figure, the sealed battery 1 stands upright so that the longitudinal direction of the sealing body 4 is perpendicular to the ground plane 40. That is, the sealed battery 1 stands upright so that the sealing body 4 is in a vertically long state.

  In FIG. 6, a compressive load F is applied to the upper end portion of the outer can 2. When the compressive load F is increased, the sealed battery 1 is not compressed in the height direction, but a buckling phenomenon occurs that suddenly curves and becomes unstable.

  Further, if there is a portion whose shape has changed in the sealing body 4, when a compressive load F is applied as shown in FIG. 6, stress concentration occurs in the portion whose shape has changed. When the buckling phenomenon as described above occurs, breakage is likely to occur in a portion where stress concentration occurs or a portion where rigidity is low.

  This will be described with reference to FIG. FIG. 7A is a diagram showing a state where the sealed battery 1 according to the present embodiment is curved. FIG. 7B is a diagram illustrating a state in which the sealed battery 100 according to the comparative example is curved. The sealed battery 100 includes the sealing body 4 having the cross-sectional shape shown in FIG. 5B, and has the same configuration as the sealed battery 1 except for this point.

  In the sealed battery 1 according to the present embodiment shown in FIG. 7A, an increase in the compressive load F causes a curve with the position of the liquid injection hole 20 as a fulcrum (P1). On the other hand, in the sealed battery 100 according to the comparative example of FIG. 7B, the increase in the compressive load F causes a curve with the position of the cleavage vent 30 as a fulcrum (P2). It was confirmed by experiments that the curve as shown in FIG. Thus, it is considered that the bending with the position of the cleavage vent 30 as a fulcrum occurs because the stress is concentrated at the position of the cleavage vent 30 and the rigidity is low.

  Specifically, in FIG. 5A, the section where the cleavage vent 30 is formed changes the cross-sectional shape of the sealing body 4 by the recess 31 and the recess 32. As a result, when a compressive load F is applied as shown in FIG. 6, stress concentrates on the portion where the cleavage vent 30 is formed. Moreover, the thin part 33 is formed of the recessed part 31 and the recessed part 32, and the formation part of the cleavage vent 30 has low rigidity.

  Here, as shown in FIG. 1, the negative electrode current collecting lead 6 is led out from the electrode body 5 in the vicinity of the cleavage vent 30. As shown in FIG. 7B, when a curve occurs with the position of the cleavage vent 30 as a fulcrum, the negative electrode current collecting lead 6 can easily come into contact with the outer can 2.

  As described above, since the outer can 2 is bonded to the sealing body 4 to which the positive electrode current collecting lead 7 is bonded, it is charged to the positive electrode potential. Therefore, when the negative electrode current collector lead 6 and the outer can 2 come into contact with each other, an internal short circuit occurs in the sealed battery 1, and the possibility of smoke generation / ignition increases. This possibility is further increased when the sealed battery 1 is further bent and damaged.

  On the other hand, even if the positive electrode current collecting lead 7 contacts the outer can 2 charged to the positive electrode potential, an internal short circuit does not occur. For this reason, as shown in FIG. 6, when a compressive load F is applied, the curve with the position of the cleavage vent 30 as a fulcrum (P2) as in the comparative example of FIG. If a curve with the position of the liquid injection hole 20 as a fulcrum (P1) occurs as shown in FIG. 7 (a), smoke and fire due to an internal short circuit can be prevented. In this case, even if the sealed battery 1 is further bent and damaged, it does not change that an internal short circuit does not occur.

  On the other hand, it is possible to prevent internal short circuit by adding an insulating tape or applying an insulating material. However, in this embodiment, such additional processing is unnecessary, which is advantageous in terms of cost.

  In addition, when a curve occurs on the liquid injection hole 20 side or when this curve further progresses and breaks, the application state of the compressive load F and the upright state of the sealed battery 1 become unstable. For this reason, it is considered that it is normal that the bending or breakage on the cleavage vent 30 side does not proceed once the bending or breakage on the liquid injection hole 20 side occurs.

  As described above, in the comparative example of FIG. 7B, the bending with the position of the cleavage vent 30 as a fulcrum occurs because the stress is concentrated at the position of the cleavage vent 30 and the rigidity is low. From this, if the cross-sectional shape of the liquid injection hole 20 is made larger than the cross-sectional shape of the cleavage vent 30 so that the stress due to the concentration of stress is increased or the rigidity is lowered, as shown in FIG. In addition, the curve having the position of the liquid injection hole 20 as a fulcrum occurs before the curve having the position of the cleavage vent 30 as a fulcrum.

  As shown in FIG. 2B and FIG. 5A, in the present embodiment, the enlarged portion 22 is formed in the liquid injection hole 20 of the sealing body 4 so that the position of the liquid injection hole 20 is a cleavage vent. The stress is more easily concentrated and the rigidity is lower than the position 30. As a result, as shown in FIG. 6, when a compressive load F is applied, a curve with the position of the liquid injection hole 20 as a fulcrum (P1) is generated as shown in FIG. 7A.

  FIG. 8A shows another example of the sectional shape of the cleavage vent, and FIG. 8B shows another example of the sectional shape of the injection hole. 8A corresponds to an enlarged view of a portion A in FIG. 2B, and FIG. 8B corresponds to an enlarged view of a portion B in FIG. 2B.

  In the cleavage vent 34 shown in FIG. 8A, the recessed portion 35 and the recessed portion 36 form a thin portion 37. A groove 38 is provided along the outer periphery of the thin portion 37 to form a thin portion 39 thinner than the thin portion 37. The dimensions of each part are, for example, the length d of the concave portion 35 and the concave portion d = 3.3 mm, the width w = 0.2 mm between the inner peripheral surface of the concave portion 36 and the groove 38, and the width w1 of the groove 38 = 0.2 mm. The thickness of the thin portion 39 is t1 = 0.03 mm.

  In the liquid injection hole 23 shown in FIG. 8B, a thin portion 27 is formed between the enlarged diameter portion 25 and the enlarged diameter portion 26, and an insertion portion 24 is formed in the thin portion 27. A groove 28 is provided in the thin portion 27 so as to surround the insertion portion 24, and a thin portion 29 thinner than the thin portion 27 is formed. The dimensions of each part are, for example, the diameter d1 = 3.3 mm of the enlarged diameter part 25 and the enlarged diameter part 26, the diameter d2 of the insertion part 24 = 1.4 mm, and the distance between the inner peripheral surface of the enlarged diameter part 25 and the groove 28. The width w2 = 0.2 mm, the width w3 of the groove 28 = 0.4 mm, and the thickness t2 of the thin portion 27 = 0.03 mm.

  In the above-described embodiment, the fulcrum of the curve when the compressive load F is applied is the position of the liquid injection hole. However, the contact between the negative electrode current collector lead 6 and the outer can 2 shown in FIG. If it can be prevented, the fulcrum of curvature may be in another position. More specifically, if the fulcrum of the curve is located on the liquid injection hole 20 side with respect to the negative electrode terminal 9, it is advantageous for preventing an internal short circuit due to contact between the negative electrode current collecting lead 6 and the outer can 2. .

  When a portion other than the position of the liquid injection hole 20 is used as a fulcrum for bending, a portion where the cross-sectional shape of the sealing body 4 is changed is formed separately from the liquid injection hole 20. For example, a groove or a recess may be formed between the negative electrode terminal 9 and the liquid injection hole 20.

  Further, in order to ensure the curvature with the position of the liquid injection hole 20 as a fulcrum, in addition to the enlarged diameter portion 20 shown in FIG. 2B and FIG. May be added. For example, a groove surrounding the liquid injection hole 20 may be added, or a groove or a recess may be added so as to sandwich the liquid injection hole 20.

  Further, in the present embodiment, the sealing body 11 illustrated in FIG. 3 has been described as an example of a two-layer structure, but may have other configurations.

  In addition, as shown in FIG. 2B, the cleavage vent has been described in the example in which the concave portion 31 and the concave portion 32 are formed in the sealing body 4, but the shape is not limited to this, and the concave portion is formed only on one side of the sealing body 4. May be provided, or a substantially rectangular groove may be formed instead of the recess.

  As described above, according to the sealed battery according to the present invention, it is advantageous for preventing an internal short circuit when an external force is applied. Therefore, the sealed battery according to the present invention is, for example, a sealed battery used for a mobile phone or a mobile device. It is useful as a battery.

DESCRIPTION OF SYMBOLS 1 Sealed battery 2 Exterior can 3 Opening of exterior can 4 Sealing body 5 Electrode body 6 Negative electrode current collection lead 7 Positive electrode current collection lead 9 Negative electrode terminal 11 Sealing body 14 Convex part 20, 23 Injection hole 21, 24 Insertion part 22 , 25, 26 Expanded diameter part 30, 34 Cleavage vent

Claims (5)

A sealed battery in which the opening of a rectangular outer can is sealed with a sealing body,
In the longitudinal direction of the sealing body, the cleavage bend and the liquid injection hole are arranged so as to sandwich the negative electrode terminal,
In the outer can, an electrode body from which a negative current collecting lead and a positive and negative current collecting lead are derived is incorporated,
The negative electrode current collector lead is on the cleavage bend side with respect to the positive and negative current collector leads,
When a compressive load is applied to the outer can so as to compress the outer can in the longitudinal direction of the sealing body,
The cross-sectional shape of the sealing body is such that the bending with respect to the position on the liquid injection hole side with respect to the negative electrode terminal occurs before the bending with respect to the position on the cleavage bend side with respect to the negative electrode terminal. A sealed battery characterized by being formed.   2. The sealed battery according to claim 1, wherein a cross-sectional shape of the sealing body is formed in a portion where the liquid injection hole is formed so that stress due to stress concentration is larger than a portion where the cleavage bend is formed.   3. The sealed battery according to claim 1, wherein a cross-sectional shape of the sealing body is formed such that a portion where the liquid injection hole is formed is lower in rigidity than a portion where the cleavage bend is formed.   The said liquid injection hole contains the insertion part in which the convex part which seals the said liquid injection hole is inserted, and the enlarged diameter part larger diameter than the said insertion part. Sealed battery.   The sealed battery according to claim 1, wherein a recess or a groove is formed separately from the liquid injection hole on the liquid injection hole side with respect to the negative electrode terminal in the sealing body.

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