JP2017069142A - Secondary battery pack structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery pack having a structure for detecting an abnormality when a unit battery suffers any abnormality and arranged to be able to stop the battery pack from outputting in response to the detection while it still has an exterior package material reduced in thickness.SOLUTION: In a secondary battery pack, a conductor is formed on a battery pack exterior package material, which is disposed on a unit battery through an insulator. A part of the conductor is connected to a protection circuit. The secondary battery pack is arranged so that the protection circuit detects the contact of a conductive part and unit battery's exterior package casing when suffering an abnormality from outside the battery pack by a something sharp and after the detection by the protection circuit, the charge and discharge of the battery protection circuit are inhibited. Further, in the event of an abnormality such that the unit battery casing is pierced, an electrolytic solution in a cell leaks, a potential difference produced between the cell casing and the conductor by the electrolytic solution is detected, and the charge and discharge of the battery protection circuit are inhibited.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a structure for detecting an abnormality in a unit cell of a secondary battery pack used in an electronic device or the like.

  As secondary battery packs used for electronic devices such as imaging devices and portable devices become smaller and thinner, battery packs tend to be smaller and thinner as well.

  Therefore, the number of battery packs with a thin battery pack outer case resin or an outer packaging material as a label is increasing. As the battery pack exterior becomes thinner, the strength (dropping, etc.) expected in normal use is secured, but the unit cell is more susceptible to abnormalities with sharp objects from the outside. Therefore, the cell may be deformed by a dent or the like, giving an abnormality to the internal electrode, and there is a risk of liquid leakage due to a hole in the can.

  In order to avoid the abnormality of the unit cell, a method of increasing the thickness of the outer packaging material as much as possible can be considered. Further, a secondary battery using a sheet having rubber elasticity as an exterior material is known (see Patent Document 1).

  However, in any of the methods, the exterior thickness increases, and in order to maintain the battery pack outer dimensions, it is inevitable to reduce the unit cell dimensions, and it is inevitable to reduce the capacity.

Japanese Patent Laid-Open No. 06-267515

  As described above, in secondary battery packs used in conventional electronic devices such as imaging devices and portable devices, the size and thickness of devices are being reduced, so the battery packs are similarly reduced in size and thickness. Along with this, the battery pack outer case resin is made thinner and the number of battery packs with the outer packaging as a label is increased, and the unit cell is more susceptible to abnormalities with sharp objects from the outside.

  As a countermeasure, secondary batteries using a sheet with rubber elasticity are known as a method for increasing the thickness of the outer packaging material to the minimum necessary to avoid abnormalities in the unit cell, and as a packaging material. In order to maintain the outer dimensions of the battery pack as the thickness increases, it is inevitable that the unit cell size is reduced, and the capacity is inevitably reduced.

  Accordingly, the present invention provides a battery pack having a structure for detecting when a battery cell is abnormal while the outer packaging material of the battery pack is kept thin, and capable of stopping the output of the battery pack by the detection. The purpose is to provide.

In order to achieve the above object, the secondary battery pack according to the present invention includes:
A conductor is formed in the battery pack exterior material, and the unit cell is arranged via an insulator, and a part of the conductor is connected to the protection circuit. The battery protection circuit is configured to detect the contact between the conductive part and the unit cell outer can when it receives a sharp abnormality from the outside of the battery pack. To be configured. Furthermore, in the case of an abnormality that penetrates the unit cell can, the electrolyte inside the cell leaks, and the potential difference generated between the cell can and the conductor due to the electrolyte is detected to charge / discharge the battery protection circuit. Configure to ban.

  According to the secondary battery pack of the present invention, a conductor is formed in the battery pack exterior material, and the unit cell is arranged via an insulator, and a part of the conductor is connected to the protection circuit, and the battery pack exterior In order to prevent the battery protection circuit from being charged / discharged after the protection circuit detects the contact between the conductive part and the unit cell outer can when it receives an abnormality from Configure. Furthermore, in the case of an abnormality that penetrates the unit cell can, the electrolyte inside the cell leaks, and the potential difference generated between the cell can and the conductor due to the electrolyte is detected to charge / discharge the battery protection circuit. By configuring so as to be prohibited, the reliability can be improved as compared with the conventional secondary battery pack.

The figure which shows the secondary battery pack of Example 1. The figure which shows the cross section of the secondary battery pack of Example 1 Detailed view of part B in FIG. Detailed view of part B in FIG. Detailed view of part C in FIG. The battery pack of Example 1 as viewed from below Protection circuit diagram of the battery pack of Example 1 The figure which shows the conventional secondary battery pack The figure which shows the cross section of the conventional secondary battery pack

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  In this embodiment, the structure of a secondary battery pack will be described by taking the battery pack of a digital camera as an example.

  FIG. 8 is a diagram showing a battery pack of a conventional digital camera, where 100 is a secondary battery pack, 101 is an upper case of the battery pack, and 102 is a lower case.

  FIG. 9 is a diagram showing a cross-section at a position D in FIG. 8, in which 103 is a unit cell, and 104 is a protection circuit board. The unit cell 103 and the protection circuit board 104 are connected to each other by a lead plate (not shown), and an IC or FET for controlling charging / discharging of the secondary battery pack 100 is mounted on the protection circuit board 104.

  The upper case 101 and the lower case 102 are made of a resin molded product such as a PC material, and the plate thickness is about 0.8 mm. The unit case 103 and the protection circuit board 104 are protected by the upper case 101 and the lower case 102, and the outer shape of the secondary battery pack 100 is defined and aligned with the secondary battery mounting portion of the digital camera.

  Incidentally, the thickness of the secondary battery pack 100 is generally about 6.0 mm or less, and the upper case 101 and the lower case 102 occupy 20% or more of the thickness of the secondary battery pack 100.

  FIG. 1 is a view showing a secondary battery pack according to the present embodiment, wherein 10 is a secondary battery pack, 11 is on the frame, 12 is under the frame, and 13 is an exterior label.

  FIG. 2 is a diagram showing a cross-section at A in FIG. 1. The secondary battery pack 10 includes a unit cell 14, a protection circuit board 15, and a detection tab 16 mounted on the protection circuit board 15. The unit cell 14 and the protection circuit board 15 are integrally connected by a lead plate, housed in an upper frame 11 and a lower frame 12, and an exterior label 13 is attached.

  FIG. 3 is a diagram showing the details of part B of FIG. 2, wherein 31 is a PET laminate, 32 is a silver sheet, 33 is an adhesive layer, and the exterior label 13 is composed of these three layers. The silver sheet 32 is printed as necessary, such as display. Reference numeral 34 denotes an outer can of the unit cell 14.

  FIG. 4 is a diagram showing a state in which an abnormality is received from the outside in FIG. 3, and 35 is a sharp object from the outside. When the external label 13 is stressed by a sharp object 35 from the outside, the PET laminate 31 bites in the direction of the silver sheet 32 while being stretched by the stress. Further, the adhesive layer 33 is formed so that the silver sheet 32 is also pushed into the PET laminate 31. I will crush it. When the adhesive layer 33 is crushed, conduction occurs between the silver sheet 32 and the outer can 35 of the unit cell 14. The PET laminate 31 is necessary to prevent the sharp object 35 from directly hitting the silver sheet 32 and breaking.

  FIG. 5 is a diagram showing details of the portion C of FIG. 2, and 51 is a hole provided in the lower frame 12. The detection tab 16 mounted on the protection circuit board 15 extends from the hole 51 to the external surface of the secondary battery pack 10 and is connected to the exterior label 13.

  FIG. 6 is a view of FIG. 5 as viewed from below, and is configured so that a part of the exterior label 13 can be extended and connected to the detection tab 16.

  FIG. 7 is a circuit diagram of the protection circuit board 14, wherein 71 is a charge control IC, 72 is an overcurrent detection terminal of the charge control IC, and 73 is a charge / discharge control FET. Further, 74 is the positive electrode of the outer can 34 by contacting the outer can 34 of the unit cell 14 with the external stress due to the sharp one 35 as explained in the silver sheet portion 32 of the outer label 13. Therefore, overcurrent detection can be performed. Furthermore, when the laminate layer 31 is penetrated from the outer can 34, the electrolytic solution inside the unit cell leaks and a potential difference is generated between the electrolytic solution and the silver sheet 32 and the outer can 34. Similarly, the protective circuit board 15 detects the potential difference. It becomes possible to do.

  In this way, a conductor is formed of a silver sheet on the battery pack outer label, and the unit cell is arranged via an adhesive, and a part of the conductor is connected to the protective circuit board, and is sharp from the outside of the battery pack. Configured to detect when the conductor is in contact with the outer can of the unit cell when the battery is damaged, and to prohibit charging / discharging of the battery protection circuit after detecting the protection circuit By doing so, reliability can be improved compared with the conventional secondary battery pack.

  Furthermore, in the case of an abnormality that penetrates the unit cell can, the electrolyte inside the cell leaks, and the potential difference generated between the cell can and the conductor due to the electrolyte is detected to charge / discharge the battery protection circuit. By configuring so as to be prohibited, the reliability is improved as compared with the conventional secondary battery pack.

10 Secondary battery pack, 11 frame top, 12 frame bottom, 13 exterior label,
14 unit cell, 15 protection circuit board, 16 detection tab, 31 PET laminate,
32 Silver sheet, 33 Adhesive layer, 34 Unit battery outer can, 35 Sharp from outside,
51 hole provided under the frame, 71 charge control IC, 72 overcurrent detection terminal,
73 FET for charge / discharge control, 74 silver sheet part of exterior label, 100 secondary battery pack,
101 upper case, 102 lower case, 103 unit cell, 104 protection circuit board

Claims (3)

A secondary battery pack comprising a battery unit capable of charging and discharging and a protective circuit board for performing charge / discharge control of the unit cell in an exterior member,
The unit has means for detecting an abnormality due to external stress to the unit cell, and the unit comprises a conductor in the exterior member in a non-contact state with the unit cell,
When an external stress that causes an abnormality of the unit cell is applied to the secondary battery pack, the conductor and the unit cell come into contact with each other due to the deformation of the exterior material, and the contact between the conductor and the unit cell is a protection circuit. A secondary battery pack, characterized by being configured to detect at The secondary battery pack according to claim 1, wherein the charge / discharge operation is stopped when an abnormality is detected. The secondary battery pack according to claim 2, wherein the abnormality detection method is configured to be shared with a protection IC overcurrent detection terminal of the protection circuit.