JP2013098108A - Secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery which, after its CID is actuated, can be safely and easily disposed of.SOLUTION: A secondary battery of the present invention comprises: a flat square shaped battery case which has a power generation element housed and hermetically sealed therein; a terminal member which is connected to the power generation element inside the battery case and which partly protrudes to the outside of the battery case, constituting an external terminal; a safety valve which is a fragile portion formed in part of the battery case; and a current interrupt device, fitted to the terminal member in the battery case, which, when a status value of the battery exceeds an actuation threshold, divides the terminal member into a portion on the power generation element side and a portion on the external terminal side to break electrical continuity. The terminal member has a conductive salient formed therein, which extends from the portion which becomes the power generation element side when the electrical continuity is broken by the current interrupt device to a position directly beneath the safety valve.

Description

  The present invention relates to a secondary battery in which a power generation element is enclosed in a battery case. More specifically, the present invention relates to a secondary battery provided with a current interrupt device (CID: Current Interrupt Device) in a battery case.

  Conventionally, in a sealed secondary battery, when an overcharge state is caused for some reason, the internal pressure of the battery may rise from the range of the normal state. Therefore, many secondary batteries have a safety valve for avoiding an excessive increase in internal pressure. This safety valve is formed more fragile than other parts, and when the internal pressure rises beyond the limit, it breaks and opens, and becomes a discharge port for discharging the gas accumulated in the battery.

  Furthermore, there is a secondary battery equipped with a CID that operates at an internal pressure that is higher than the internal pressure in the normal state and lower than the valve opening pressure of the safety valve (see, for example, Patent Document 1). The CID described in this document has a “diaphragm 35” formed by bending a metal plate. When the secondary battery is in a high internal pressure state due to overcharging or the like, the “diaphragm 35” is pushed up and deformed. When the “diaphragm 35” is deformed, the “connection metal 34” connected to the electrode plate is separated from the “diaphragm 35”, and the conduction between them is cut off. As a result, the current path is interrupted at this point, so that the battery is not charged or discharged any further.

JP 2010-157451 A

  When the CID is activated, the battery may be overcharged. Since the current path is interrupted by the operation of the CID, no further charge / discharge is performed on the battery. However, it cannot be said that a method for safely handling a battery that has been in an overcharged state after the CID is operated, for example, for recycling, has not been established. In particular, there is a problem that it is not easy to handle a secondary battery in which the CID is activated but the safety valve is not opened. In the above-mentioned patent document, there is no description about handling of the secondary battery after CID operation.

  The present invention has been made to solve the above-described problems of the prior art. That is, the problem is to provide a secondary battery that can be safely and easily disposed of after the CID is activated.

  The secondary battery of the present invention, which has been made for the purpose of solving this problem, is connected to the power generation element inside the battery case with a flat rectangular battery case that contains the power generation element and is sealed inside, A terminal member that is an external terminal partly protruding outside the battery case, a safety valve that is a weak spot formed in a part of the battery case, and a terminal member provided inside the battery case, And a current interruption mechanism that divides the terminal member into a power generation element side part and an external terminal side part when the state value of the current rises exceeding a predetermined operating threshold, The member is formed with a conductive convex portion extending from a portion on the power generation element side when conduction is cut off by the current cut-off mechanism to a position directly below the safety valve.

  According to the secondary battery of the present invention, when the current interruption mechanism is activated, the terminal member is divided into the power generation element side portion and the external terminal side portion. That is, the interruption operation by this current interruption mechanism is generally an irreversible operation. And in this invention, the electroconductive convex part extended to the position directly under a safety valve is formed in the part which becomes a power generation element side among terminal members. That is, if a conductive member is inserted from the outside of the battery case into the position of the safety valve, the member and the conductive convex portion formed on the secondary battery can be conducted. In this state, the battery can be discharged if the conductive member is connected to the terminal of the other electrode not provided with the current interruption mechanism. Therefore, after the current interruption mechanism is activated, the battery can be disposed of safely and easily.

Furthermore, in the present invention, it is desirable that the state value is a pressure value in the battery case.
Alternatively, as the state value, a temperature in the battery case, a current value flowing through the battery, or the like can be used. Alternatively, the present invention can be applied to a current interrupting mechanism that operates according to any of these plurality of state values.

  According to the secondary battery of the present invention, after the CID is activated, the battery can be disposed of safely and easily.

It is a front view which shows schematic structure of the secondary battery which concerns on this form. It is a side view of a secondary battery. It is explanatory drawing which shows a mode that the discharge of a secondary battery is performed.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this embodiment, the present invention is applied to a sealed prismatic secondary battery such as a lithium ion secondary battery.

  The battery 10 of this embodiment is a flat lithium ion secondary battery. A schematic configuration of the battery 10 of this embodiment is shown in FIGS. The battery 10 according to this embodiment has a battery case 13 formed by joining a case main body 11 and a lid member 12 and an electrode body 15 in which a band-shaped electrode plate and a separator are overlapped and wound flat. . The battery case 13 is a flat rectangular metal case that is thin in the depth direction in the figure. The case main body 11 has a box shape with only one upper surface opened in the figure, and the opening portion is sealed with a lid member 12.

  The battery 10 has a positive electrode terminal 21 and a negative electrode terminal 22 as shown in FIG. The positive electrode terminal 21 and the negative electrode terminal 22 protrude from the lid member 12 of the battery case 13 to the outside of the battery 10. The positive electrode terminal 21 is connected to the positive electrode plate 15 a of the electrode body 15 inside the battery case 13 via the positive electrode internal terminal 31. The negative electrode terminal 22 is connected to the negative electrode plate 15 b of the electrode body 15 inside the battery case 13 via the negative electrode internal terminal 32. FIG. 2 is a side view of the battery 10 as viewed from the positive electrode terminal 21 side (left side in FIG. 1).

  As shown in FIG. 1, the lid 12 has a safety valve 35 formed at the center in the longitudinal direction. The safety valve 35 is a location where the thickness of the lid member 12 is partially reduced, and is a weak location compared to other locations. When the internal pressure of the battery 10 rises above a predetermined valve opening pressure of the safety valve 35, the safety valve 35 is destroyed and the gas accumulated inside is discharged. Thereby, the internal pressure of the battery 10 can be lowered. That is, since the valve opening pressure of the safety valve 35 is appropriately set, the internal pressure of the battery 10 does not increase too much.

  During normal use of the battery 10 of this embodiment, the internal pressure changes in accordance with the usage situation within a predetermined range lower than the valve opening pressure of the safety valve 35. Hereinafter, this pressure range during normal use is referred to as normal pressure. As shown in FIG. 1, the battery 10 has a CID 37 between the positive electrode internal terminal 31 and the positive electrode terminal 21. The CID 37 operates when the internal pressure of the battery 10 exceeds a predetermined operating pressure, and interrupts the current path at the location of the CID 37. The operating pressure of the CID 37 is set to a value that is lower than the valve opening pressure of the safety valve 35 and higher than the upper limit value of the normal pressure.

  The CID 37 has a structure in which a member that deforms when subjected to a pressure of a certain level or more and the current path is blocked by the deformation of the member. Various internal structures of the CID 37 have been proposed in the past, and may be appropriately selected from these structures. For example, it may be described in Patent Document 1 described above. Alternatively, it may be described in the international publication number WO2010 / 146701A1 previously filed by the present applicant. The CID 37 of this embodiment is provided on the inner surface side of the lid member 12 inside the battery case 13. When the internal pressure of the battery case 13 exceeds the operating pressure, the CID 37 operates and the current path is interrupted between the positive electrode internal terminal 31 and the positive electrode terminal 21.

  Furthermore, as shown in FIG. 1, the positive electrode internal terminal 31 of this embodiment is provided with a discharge convex portion 39. The discharge convex portion 39 is electrically connected to the positive electrode internal terminal 31 and is disposed so as not to be electrically connected to the lid member 12 and the battery case 13. The discharge convex portion 39 is obtained, for example, by using a positive electrode internal terminal 31 that is manufactured in a protruding shape. Alternatively, the discharge convex portion 39 may be formed separately from the positive electrode internal terminal 31, and these may be joined or attached to be electrically connected.

  The discharge convex portion 39 is provided at a location between the location connected to the CID 37 and the location connected to the positive electrode plate 15 a of the electrode body 15 in the positive electrode internal terminal 31. The discharge convex portion 39 of this embodiment extends at least directly below the safety valve 35 along the longitudinal direction of the lid member 12 of the battery 10. In other words, at least a part of the discharge convex portion 39 is disposed in a cylindrical range extending toward the inside of the battery 10 so that the range of the safety valve 35 is perpendicular to the surface forming the lid member 12. Note that, during normal use of the battery 10, the discharge convex portion 39 does not play a special role.

  While the battery 10 is being used, the internal pressure may increase for some reason and may exceed the upper limit of the normal pressure. When the internal pressure exceeds the operating pressure of the CID 37, the CID 37 operates and the conduction between the positive electrode internal terminal 31 and the positive electrode terminal 21 is interrupted. In this case, the positive electrode terminal 21 exposed to the outside of the battery 10 is no longer connected to the positive electrode plate 15 a of the electrode body 15.

  Therefore, even if a voltage is applied between the positive electrode terminal 21 and the negative electrode terminal 22, the battery 10 in which the CID 37 is activated does not apply a voltage to the electrode body 15, so there is no risk of further charging. Further, even if the positive electrode terminal 21 and the negative electrode terminal 22 of the battery 10 in which the CID 37 is operated are simply connected outside the battery case 13, they cannot be discharged as they are. However, even in this state, since the discharge convex portion 39 is on the positive electrode internal terminal 31 side, conduction between the discharge convex portion 39 and the positive electrode plate 15a of the electrode body 15 is maintained. Note that the battery 10 in which the CID 37 is activated cannot be reused as it is.

The battery 10 in which the CID 37 is activated is usually overcharged. If the internal pressure further increases and exceeds the valve opening pressure of the safety valve 35 even after the operation of the CID 37, the internal pressure may be lowered, but it is often electrically overcharged. . Therefore, considerable caution is required for handling as it is. The battery 10 of this embodiment can be easily discharged after the CID 37 is activated. The discharged battery 10 does not require any special care in handling.

  When discharging the battery 10 of this embodiment in which the CID 37 is operated, as shown in FIG. 3, the discharge rod 41 is inserted into the safety valve 35, and the discharge rod 41 and the negative electrode 22 are energized through the resistor 42. The discharge rod 41 is used for this discharge treatment, and is a conductive rod-shaped member. The resistor 42 is a member for causing a gradual discharge so that a large current does not flow suddenly.

  If the safety valve 35 is open, it is a through hole. Even if the valve is not opened, the safety valve 35 is weaker than other parts, and can be easily penetrated by inserting the discharge rod 41. That is, it can be opened from the outside. Therefore, it is easy to insert the discharge rod 41.

  As described above, a portion of the discharge convex portion 39 is disposed immediately below the safety valve 35. Therefore, the discharge rod 41 inserted from the safety valve 35 into the battery 10 contacts the discharge convex portion 39. Thereby, the discharge rod 41 is electrically connected to the positive electrode internal terminal 31. Therefore, by making the discharge rod 41 and the negative electrode terminal 22 conductive, the positive electrode plate 15a and the negative electrode plate 15b become conductive, and the battery 10 can be forcibly discharged.

  As described in detail above, the battery 10 of this embodiment has the discharge convex portion 39 that is electrically connected to the positive electrode internal terminal 31 and extends to just below the safety valve 35. Accordingly, by inserting the discharge rod 41 from the location of the safety valve 35, the discharge rod 41 and the positive electrode internal terminal 31 can be easily conducted. When conduction between the positive electrode terminal 21 and the positive electrode internal terminal 31 is interrupted by the operation of the CID 37, it is easy to discharge the battery 10 by inserting the discharge rod 41 and conducting with the negative electrode terminal 22. Therefore, the battery 10 in which the CID 37 is activated can be disposed of safely and easily.

In addition, this form is only a mere illustration and does not limit this invention at all. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof.
For example, in the above embodiment, the CID 37 is provided between the positive electrode terminal 21 and the positive electrode internal terminal 31, and the positive electrode internal terminal 31 has the discharge convex portion 39. It may be provided. Further, a part of the discharge convex portion 39 may be fixed at a position directly below the safety valve.

DESCRIPTION OF SYMBOLS 10 Battery 13 Battery case 15 Electrode body 15a Positive electrode plate 21 Positive electrode terminal 31 Positive electrode internal terminal 35 Safety valve 37 CID
39 Discharge convex part

Claims (2)

A flat rectangular battery case that contains a power generation element and is sealed;
A terminal member that is connected to the power generation element inside the battery case and is an external terminal that partially protrudes outside the battery case;
A safety valve that is a weak spot formed in a part of the battery case;
Provided in the terminal member inside the battery case, and when the state value of the battery exceeds a predetermined operating threshold value, the terminal member is divided into a part on the power generation element side and a part on the external terminal side Current interruption mechanism for interrupting conduction,
The terminal member is formed with a conductive projection extending from a portion on the power generation element side when conduction is cut off by the current cut-off mechanism to a position directly below the safety valve. Next battery. The secondary battery according to claim 1,
The secondary battery, wherein the state value is a pressure value in the battery case.

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