JP2014197463A - Battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely and electrically disconnect a battery in which a safety valve mechanism is activated from an electrical circuit.SOLUTION: A battery 10 comprises: a conductive battery case 20 formed in a bottomed cylindrical shape; an electrode group 18 housed in the battery case; a conductive one-side terminal plate sealing an opening of the battery case; and an internal lead 36 extending from the electrode group 18 and connected to an inner surface of a bottom portion 21 of the battery case constituting the other-side terminal plate. An outer lead 46 is connected to the bottom portion 21 of the battery case. The bottom portion 21 includes, on its outer surface, an inner-peripheral thin-wall portion 42 formed to surround the center of the bottom portion over the whole circumference and an outer-peripheral thin-wall portion 44 formed on an outer peripheral side of the inner-peripheral thin-wall portion 42 and having a shallower cut depth than the inner-peripheral thin-wall portion 42. The inner lead 36 is connected to a bottom region 21a inside the inner-peripheral thin-wall portion 42, and the outer lead 46 is connected to a bottom region 21b between the inner-peripheral thin-wall portion and the outer-periphery thin-wall portion.

Description

  The present invention relates to a battery, and more particularly to a battery provided with a safety valve mechanism on the bottom surface of a battery case.

  Conventionally, a configuration in which a safety valve mechanism is provided on the bottom surface of a secondary battery such as a lithium battery is known.

  For example, in Patent Document 1 below, in a sealing lid of a nonaqueous electrolyte secondary battery, after forming a thin portion by machining or the like in a safety valve forming region and at least forming a fragile portion, It is described that a weak part is formed by irradiating a predetermined position of a thin part formed in a part with a laser, and a safety valve including the weak part is formed.

  Patent Document 2 below discloses a groove-like thin wall in which a cleavage line portion is extended outwardly in a substantially semicircular portion formed in a substantially semicircular shape with the center of the bottom portion of a bottomed cylindrical negative electrode can as a center. Explosion-proof electrical elements that employ parts are described.

Japanese Patent Laid-Open No. 2002-8616 JP-A-9-115497

  It is desirable to ensure that the battery is electrically disconnected from the electrical circuit when the safety valve mechanism is activated in the battery.

  A battery according to the present invention includes a conductive battery case having a bottomed cylindrical shape, an electrode group housed in the battery case, a conductive one-side terminal plate that seals an opening of the battery case, and an electrode group An internal lead connected to the inner surface of the bottom of the battery case constituting the other side terminal plate, and the external lead is connected to the outer surface of the bottom, wherein the bottom of the battery case is An inner lead including an inner peripheral thin portion formed by surrounding the central portion over the entire circumference, and an outer peripheral thin portion formed on the outer peripheral side of the inner peripheral thin portion and having a cutting depth shallower than the inner peripheral thin portion. Is connected to the bottom region inside the inner peripheral thin portion, and the external lead is connected to the bottom region between the inner peripheral thin portion and the outer peripheral thin portion.

  According to the battery of the present invention, the battery in which the safety valve mechanism is operated can be reliably electrically separated from the electric circuit.

It is sectional drawing which shows schematic structure of the battery which is one of embodiment. It is the (a) bottom view of the battery shown in FIG. 1, and (b) sectional drawing of the bottom part. It is an enlarged view of the bottom part of FIG.2 (b). It is the (a) bottom view of the battery which shows an example of the safety valve mechanism of the battery which is an experiment example, and (b) sectional drawing of the bottom part. It is a figure which shows a mode when the safety valve mechanism of the battery shown in FIG. 4 act | operates. It is a figure which shows a mode that the bottom part of the battery of embodiment is cleaved. FIG. 7 is a diagram illustrating a state in which the bottom of the battery is cleaved, following FIG. 6. It is a figure which shows the modification of the thin part which comprises a safety valve mechanism. It is a figure which shows the other modification of the thin part which comprises a safety valve mechanism. It is a figure which shows the example which provided the fracture | rupture planned part in the external lead.

  Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. In this description, specific shapes, materials, numerical values, directions, and the like are examples for facilitating the understanding of the present invention, and can be appropriately changed according to the application, purpose, specification, and the like. In addition, when a plurality of embodiments and modifications are included in the following, it is assumed from the beginning that these characteristic portions are used in appropriate combinations.

  FIG. 1 is a cross-sectional view illustrating a schematic configuration of a battery 10 according to one embodiment. The battery 10 is also called a unit cell or a battery cell, and can be used as a power source for portable electronic devices such as personal computers. Alternatively, a large number of batteries 10 may be combined and used as a power source for an electric vehicle or the like. Alternatively, a large number of batteries 10 may be combined and used as a stationary power source installed in a factory or home.

  As the battery 10, a lithium ion secondary battery that is a cylindrical non-aqueous electrolyte secondary battery can be adopted. The battery 10 is not limited to a lithium ion secondary battery, and various secondary batteries or primary batteries can be used.

  As shown in FIG. 1, a battery 10 is a battery having a bottomed cylindrical shape together with a nonaqueous electrolyte in a state where an electrode group 18 in which a separator 16 is disposed between a positive electrode 12 and a negative electrode 14 is wound. Housed in the case 20. Insulating plates 22 and 24 are disposed above and below the electrode group 18.

  A positive electrode lead 26 extends obliquely upward from the positive electrode 12 of the electrode group 18. The positive electrode lead 26 is joined to a connecting member 28 made of a metal plate by welding or the like. An inner cap 30 made of a metal plate is connected on the connection member 28. A terminal plate 32 also serving as a positive terminal is connected on the inner cap 30. The connecting member 28, the inner cap 30, and the terminal plate 32 seal the upper opening of the battery case 20 in a state where the connecting member 28, the inner cap 30, and the terminal plate 32 are integrated with each other by an insulating gasket 34 that surrounds them.

  In addition, while using the metal inner cap 30 as a valve body, a safety valve mechanism may be provided on the positive electrode side by forming through holes in the connection member 28 and the terminal plate 32, respectively.

  A negative electrode lead 36 extends from the negative electrode 14 of the electrode group 18 housed in the battery case 20. The negative electrode lead 36 bends substantially in an L shape and sinks under the insulating plate 24, and extends along the inner surface of the bottom portion 21 of the battery case 20. The bottom 21 of the battery case 20 also serves as the negative terminal of the battery 10 and is provided with a safety valve mechanism as will be described later.

  Next, with reference to FIG. 2 and FIG. 3, the safety valve mechanism 40 provided in the battery 10 of the embodiment will be described. 2A is a bottom view of the battery 10 shown in FIG. 1, and FIG. 2B is a cross-sectional view of the bottom. FIG. 3 is an enlarged view of the bottom of FIG.

  As shown in FIG. 2, in the battery 10 of the embodiment, a safety valve mechanism 40 is provided on the outer surface of the bottom portion 21 of the battery case 20. The safety valve mechanism 40 includes an inner peripheral thin portion 42 and an outer peripheral thin portion 44 formed as a double circle on the outer surface of the bottom portion 21 of the battery case 20. The inner thin part 42 and the outer thin part 44 are preferably formed concentrically. However, the present invention is not limited to this, and the centers of the thin parts 42 and 44 may be shifted from each other. Moreover, although it is preferable that the center of the inner peripheral thin part 42 corresponds with the center of the bottom 21 which makes | forms a circle, it is not limited to this, You may shift | deviate from the center of the bottom 21.

  The inner peripheral thin wall portion 42 is formed so as to surround the central portion of the bottom portion 21 of the battery case 20 having a circular shape over the entire circumference. That is, a region surrounded by the inner peripheral thin portion 42 is formed as the central valve region 21a. The end of the internal lead 36 is joined to the inner surface of the central valve region 21a by welding or the like.

  When the pressure and temperature inside the battery rise and the inner peripheral thin portion 42 is broken, the central valve region 21a of the bottom 21 is cleaved to form an opening. Even when the inner peripheral thin portion 42 is broken, the internal lead 36 is in a state of being joined to the central valve region 21a.

  The outer peripheral thin portion 44 is formed on the outer peripheral side of the inner peripheral thin portion 42 so as to surround the entire circumference of the inner peripheral thin portion 42. As a result, an annular valve region 21 b is formed between the outer peripheral thin portion 44 and the inner peripheral thin portion 42. The end of the external lead 46 connected to the negative terminal of the battery 10 is joined to the annular valve region 21b by welding or the like. The external lead 46 is formed by a conductive wire. However, it is not limited to this, and the external lead 46 may be formed of a thin metal plate.

  Referring to FIG. 2B and FIG. 3, the inner peripheral thin portion 42 and the outer peripheral thin portion 44 are both configured by V-shaped cut grooves. These cut grooves can be formed by pressing a V-shaped circular shape against the bottom 21 of the battery case 20 and engraving them, but may be formed by other methods (for example, cutting or the like). .

  Further, the cut depth d2 of the outer peripheral thin portion 44 is formed shallower than the cut depth d1 of the inner peripheral thin portion 42. In other words, the cut depth d1 of the inner peripheral thin portion 42 is formed deeper than the cut depth d2 of the outer peripheral thin portion 44. As a result, at a lower battery internal pressure or operating pressure, the inner peripheral thin portion 42 is set to break before the outer peripheral thin portion 44, and the central valve region 21a is opened.

  Next, the operation of the battery 10 including the safety valve mechanism 40 having the above configuration will be described in comparison with an experimental example. First, the operation of the safety valve mechanism in the battery 11 of the experimental example will be described with reference to FIGS. 4 and 5, and then the operation of the safety valve mechanism 40 of the battery 10 of the embodiment will be described.

  4A is a bottom view of the battery and FIG. 4B is a cross-sectional view of the bottom portion showing an example of the safety valve mechanism of the battery 11 as an experimental example. FIG. 5 is a diagram illustrating a state when the safety valve mechanism of the battery 11 illustrated in FIG. 4 is operated.

  As shown in FIG. 4, in the battery 11 of the experimental example, a thin-walled portion 43 including one circular cut groove is formed in the central valve region 21 c of the bottom portion 21 of the battery case 20. The end portion of the internal lead 36 is joined to the inner surface of the central valve region 21c surrounded by the thin portion 43, and the end portion of the external lead 46 is joined to the outer surface thereof.

  In this case, when the internal pressure of the battery 11 exceeds a predetermined threshold value, the circular thin portion 43 is broken and the central valve region 21c is opened as shown in FIG. Thereby, the high temperature gas G is ejected from the inside of the battery case 20 to the outside from the open area of the bottom part 21.

  However, in this experimental example, the internal lead 36 may remain bonded to the inner surface of the central valve region 21c after being broken from the bottom 21 and the external lead 46 may remain bonded to the outer surface. As a result, the battery 11 in which the safety valve mechanism has been operated remains connected to the electric circuit including the battery 11 and cannot be disconnected from the electric circuit.

  Further, as shown in FIG. 5B, the central valve region 21c in which the internal lead 36 and the external lead 46 are joined cannot be greatly separated from the bottom 21 of the battery case 20, and is inclined obliquely. It tends to be opened. In this case, since the exhaust opening area from which the high temperature gas can be ejected is small, there is also a problem that the temperature of the ejected gas cannot be effectively reduced. In addition, there is a knowledge that if the opening area when releasing the inside of the battery that has become high pressure is large, the degree of temperature decrease tends to increase due to the rapid volume expansion of the ejected gas.

  On the other hand, in the battery 10 of the embodiment, as shown in FIG. 6, when the inside of the battery reaches a high pressure exceeding a predetermined threshold, the central valve region 21 a having a relatively low operating pressure is first removed from the bottom 21 of the battery case 20. Break and open. Thereby, the high temperature gas G is ejected from the central opening formed in the bottom 21. Therefore, the pressure inside the battery is slightly reduced.

  At this time, since only the internal lead 36 is connected to the central valve region 21a and the external lead 46 is not connected, the central valve region 21a separated by the fracture of the inner peripheral thin portion 42 is at a position slightly away from the bottom portion 21. It becomes possible to move. Accordingly, the internal lead 36 is separated from the external lead 46, and the battery 10 in which the safety valve mechanism 40 is operated can be reliably electrically disconnected from the electric circuit.

  When the high temperature gas is ejected from the opening of the central valve region 21a, the pressure inside the battery is slightly reduced, but the increase in the amount of gas generated inside the battery exceeds the amount of gas ejected. The pressure inside the battery rises again.

  When the internal pressure of the battery exceeds the set breaking pressure of the outer peripheral thin portion 44, the outer peripheral thin portion 44 is broken in FIG. 7 and the bottom portion 21 of the battery case 20 is greatly opened. Thereby, the high temperature gas G can be ejected from the inside of the battery through the opening that is largely open to the battery bottom 21. As a result, the temperature of the hot gas ejected from the large opening can be effectively reduced. Therefore, it is possible to suppress the influence on other batteries arranged close to the periphery of the battery 10.

  As described above, according to the embodiment, the battery 10 in which the safety valve mechanism is operated can be reliably electrically disconnected from the electric circuit. Moreover, the influence on the other battery arrange | positioned adjacent to the battery 10 in which the safety valve mechanism act | operated can be suppressed.

  Next, a modification of the above embodiment will be described with reference to FIGS. In the above description, it has been described that the inner peripheral thin portion 42 and the outer peripheral thin portion 44 are both formed in a circular shape. However, the present invention is not limited to this. For example, as shown in FIG. 8A, the inner thin portion 42 and the outer thin portion 44 may both be formed in a rectangular shape such as a square, or other shapes such as a triangle, an ellipse, and a star shape. May be formed. As shown in FIGS. 8B and 8C, the inner thin portion 42 and the outer thin portion 44 may be formed in a rectangular shape and the other in a circular shape.

  Moreover, in the said embodiment, although the outer peripheral thin part 44 demonstrated that what was formed surrounding the perimeter outside the inner peripheral thin part 42, it is not limited to this, For example, it shows in FIG. As described above, the outer peripheral thin portion 44 surrounds substantially the entire circumference of the inner peripheral thin portion 42, but may be formed to include a non-thin portion 45 that is formed in a substantially C shape and is not a thin portion.

  Furthermore, as shown in FIG. 10, the fracture is scheduled to break when the central valve region 21 a is cleaved in the vicinity of the end of the external lead 46 connected to the central valve region 21 a of the bottom 21 defined by the inner peripheral thin portion 42. A portion 48 may be formed. The planned fracture portion 48 may be formed as a portion that is easily broken by forming a cut in the external lead 46, or may be formed as a portion that is easily broken by laser processing or the like. .

  Note that the battery according to the present invention is not limited to the above-described embodiments and modifications thereof, and various modifications and improvements can be made within the scope of matters described in the claims of the present application and their equivalents. Of course.

  10, 11 battery, 12 positive electrode, 14 negative electrode, 16 separator, 18 electrode group, 20 battery case, 21 bottom, 21a, 21c central valve region, 21b annular valve region, 22, 24 insulating plate, 28 connecting member, 30 inner cap , 32 Terminal plate, 34 Gasket, 36 Internal lead, 40 Safety valve mechanism, 42 Inner peripheral thin part, 43 Thin peripheral part, 44 Outer peripheral thin part, 45 Non-thin part, 46 External lead, 48 Expected fracture part, G gas.

Claims (3)

A conductive battery case with a bottomed cylindrical shape;
An electrode group housed in the battery case;
A conductive one-side terminal plate that seals the opening of the battery case;
An internal lead that extends from the electrode group and is connected to the inner surface of the bottom portion of the battery case that constitutes the other terminal plate, and a battery in which an external lead is connected to the outer surface of the bottom portion,
The bottom part of the battery case is formed on the outer peripheral side of the inner peripheral thin part formed so as to surround the central part of the bottom part over the entire circumference, and the depth of cut from the inner peripheral thin part is Including a shallow outer peripheral thin-walled portion,
The internal lead is connected to a bottom region inside the inner peripheral thin portion, and the external lead is connected to a bottom region between the inner peripheral thin portion and the outer peripheral thin portion;
battery.   The battery according to claim 1, wherein the outer peripheral thin portion has a circular shape surrounding the outer peripheral side of the inner peripheral thin portion.   The battery according to claim 1, wherein the thin outer peripheral portion is C-shaped.

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