JP2014116138A - Battery pack and electronic device provided with battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that the outer face of a unit cell is exposed from a bulging detection part provided on a label stuck to the unit cell, causing external short-circuiting to occur.SOLUTION: In a battery pack provided with a unit cell and a label stuck to the outer face of the unit cell, the label has a base material layer provided with a bulging detection part formed by cutting in from a surface layer, one face of the base material layer being stuck to the outer face of the unit cell via an adhesive material, and other faces of the base material layer having a permeable protective layer stuck thereto via an adhesive material, the protective layer covering at least a portion facing the bulging detection part so that when the unit cell bulges, the protective layer prevents the outer face of the unit cell from being exposed from the bulging detection part.

Description

  The present invention relates to a battery pack having a function of detecting swelling of a unit cell and an electronic device including the battery pack.

  In recent years, chargeable / dischargeable nonaqueous electrolyte secondary batteries such as lithium ion secondary batteries are mainly used as power sources for portable electronic devices such as video cameras, mobile computers, and mobile phones that are rapidly spreading. . A lithium ion secondary battery is configured by housing an electrode group formed by making a positive electrode and a negative electrode face each other via a separator, and a nonaqueous electrolyte in an outer case made of aluminum or an aluminum alloy. Typical cell shapes include a rectangular battery having a rectangular parallelepiped shape, a cylindrical battery having a cylindrical shape, a flat laminate battery, and the like.

For example, in the case of a rectangular battery, an electrode group and a nonaqueous electrolyte are housed in a bottomed box-shaped outer can made of aluminum or an aluminum alloy, and an opening surface of the outer can is sealed with a sealing plate. The positive electrode terminal is an outer can of the unit cell and a sealing plate, and the negative electrode terminal is a convex electrode that is insulated from the sealing plate and provided on the sealing plate.
In the case of a battery pack using this rectangular battery, on one side of this unit cell, there is a protection circuit that controls the battery voltage to prevent overcharge and overdischarge, and power is taken out from the unit cell or from the outside. The battery core is configured by disposing a protective circuit board having an input / output terminal for taking in. The protective circuit board and the unit cell are electrically connected by a connecting lead plate.

  Furthermore, the battery pack is formed by covering the four side surfaces of the battery core, that is, the four side surfaces of the outer case of the rectangular battery made of aluminum or aluminum alloy with a resin label made of an insulating material.

  In the unit cell, the non-aqueous electrolyte may be decomposed to generate gas due to excessive charging / discharging, standing at a high temperature, dropping the battery pack, or the like, and the internal pressure may increase to swell. Patent Document 1 discloses a battery pack attached so that a label is wound around the outer surface of a rectangular battery. The label affixed to the outer surface of the rectangular battery is provided with a bulge detector provided with a notch groove having a predetermined depth and a predetermined length that functions as a bulge detector. When the unit cell expands due to the use environment described above, a stress is generated at the time of expansion, and this stress opens the label bulge detection unit and causes a slit-shaped tear. Therefore, by visually observing that the outer surface of the unit cell is exposed from the slit-shaped rift, the user can easily recognize the swelling of the unit cell and determine the deterioration.

JP 2009-9734 A JP 2009-37961 A JP 2009-224049 A

7 and 8 are partially enlarged cross-sectional views of the conventional battery pack, and show portions corresponding to the cross-sectional view taken along the line AA in the battery pack of the present invention shown in FIG. The swelling detection part 31C which is a cut groove of the label 31 is opened by the stress generated when the unit cell 21 swells, and a tear 31S is generated. Therefore, the outer surface of the unit cell 21 is exposed from the tear 31S. FIG. 7 shows a state before the unit cell 21 swells, and FIG. 8 shows a swell detector 31C of the label 31 when the unit cell 21 swells. The user can easily determine the deterioration of the unit cell 21 by visually observing that the outer surface of the unit cell 21 is exposed from the slit-shaped slit 31S. However, the outer case of the unit cell 21 may also be used as an electrode terminal. For this reason, when a tear 31S occurs in the label swelling detection part 31C, the electrode terminal is exposed on the outer surface of the battery pack, and an external short circuit is caused. May occur. As a result, there arises a problem that the safety of the battery pack cannot be ensured. On the other hand, in order to ensure the safety of the battery pack, when the blister detection part 31C that is a cut groove is not provided on the label attached to the outer surface of the unit cell 21 and the tear 31S is not generated, There arises a problem that blisters cannot be visually recognized.

  Therefore, the present invention has been made in view of the above problems. In the present invention, a swollen detection portion that is a cut groove is provided on a label attached to the outer surface of a unit cell so that a user can recognize a tear in the label caused by the swollen unit cell and easily determine deterioration of the unit cell. However, it is possible to prevent the external short circuit caused by the outer surface of the unit cell exposed from the tear of the label and to secure the safety of the battery pack.

  In order to solve the above-described problem, an aspect of the present invention provides a battery pack including a unit cell and a label attached to the outer surface of the unit cell. The label includes a swelling detection unit that is cut from a surface layer. A substrate layer, and one surface of the substrate layer is adhered to the outer surface of the unit cell via an adhesive material, and the other surface of the substrate layer is provided with a permeable protective layer via the adhesive material. It is stuck.

  In the electronic device provided with the battery pack of the present invention, in the state where the battery pack is mounted on the electronic device, the bulge detection unit is located on the opposite side of the surface facing the electronic device.

  In the battery pack of the present invention, the label attached to the outer surface of the unit cell has a base material layer provided with a swollen detection part cut out from the surface layer, and one surface of the base material layer is interposed via an adhesive material. When the battery expands beyond the specified dimensions due to the structure in which the outer surface of the unit cell is attached, and the other surface of the base material layer is attached with a permeable protective layer via an adhesive, Even when the outer surface of the unit cell is exposed from the swelling detection part of the base layer due to the stress that the unit cell expands, the swelling detection part of the base layer is transparent. Since it is covered with the protective layer, it is possible to appropriately insulate the outer surface of the unit cell and prevent an external short circuit due to the outer surface of the unit cell being exposed to the outer surface of the battery pack. Furthermore, since the protective layer is permeable, the user can determine deterioration of the unit cell by visually observing the swollen detection part.

  Further, in the electronic device provided with the battery pack of the present invention, in the state in which the battery pack is disposed in the electronic device, the swelling detector is located on the opposite side of the surface facing the electronic device. Even if it is in the state arrange | positioned at an electronic device, it has the effect that a swelling detection part can be visually recognized easily.

It is an external appearance perspective view which shows the battery pack of this invention. It is a disassembled perspective view which shows the battery pack of this invention. It is a perspective view which shows the battery core of this invention. It is the elements on larger scale of the AA cross section of the battery pack shown in FIG. 1 in the state which the battery has not expanded. It is the elements on larger scale of the AA line cross section of the battery pack shown in FIG. 1 in the state which the battery expanded. It is the top view which showed the state with which the battery pack of this invention was mounted | worn with the electronic device. In the battery pack of a prior art example, it is the elements on larger scale which showed the cross section corresponding to FIG. 4 of this invention. In the battery pack of a prior art example, it is the elements on larger scale which showed the cross section corresponding to FIG. 5 of this invention.

Hereinafter, embodiments of the present invention will be described. Needless to say, the present invention is not limited to the following embodiments, and can be modified as appropriate without departing from the technical scope of the present invention. <Embodiment>
1. Appearance Configuration of Battery Pack 1 An appearance configuration of the battery pack 1 according to the embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is an external perspective view of the battery pack 1 as viewed from the upper surface side, and FIG. 2 is an exploded perspective view of the battery pack 1.

  As shown in FIG. 2, the battery pack 1 includes a flat rectangular unit cell 2. A long circuit board 5 is disposed so as to face the sealing plate 2 a of the unit cell 2, and the bottom surface of the unit cell 2. A bottomed cylindrical cap 4 having substantially the same shape as the sealing plate 2a is disposed on the sealing plate 2a side of the unit cell 2 so as to cover the circuit board 5 from the outside. Further, the battery pack 1 is configured such that a label 3 is attached so as to cover the outer periphery of the unit cell 2 and a part of the cap 4 in a state where the cap 4 is disposed on the sealing plate 2a side of the unit cell 2. Yes.

2. Internal structure of battery pack 1 The internal structure of the battery pack 1 will be described with reference to FIG.

  As shown in FIG. 2, the unit cell 2 has a flat and rectangular shape with an outer appearance, and the exterior is configured by a flat rectangular bottomed cylindrical outer can and a sealing plate 2 a that closes the opening. Has been. The sealing plate 2a is provided with a negative electrode terminal 2c protruding outward from the outer surface of the sealing plate 2a. The sealing plate 2a and the negative electrode terminal 2c are electrically insulated from each other, and the sealing plate 2a is a positive electrode. A clad plate 2b is joined to a part of the outer surface of the sealing plate 2a. The clad plate 2b has one main surface made of aluminum or an alloy material thereof, and the other main surface made of nickel. The sealing plate 2a is made of aluminum or an alloy material thereof, and is joined so that the sealing plate 2a and one main surface of the clad plate 2b are in close contact with each other.

  As shown in FIGS. 2 and 3, the circuit board 5 has a long and long shape, and is arranged so that the main surface of the circuit board 5 and the sealing plate 2 a face each other. A protection circuit for preventing overcharge and overdischarge of the unit cell 2 is mounted on the surface of the circuit board 5 facing the sealing plate 2a. On the other surface of the circuit board 5, an external connection terminal 5 </ b> A and a test terminal 5 </ b> T are provided that are positive and negative terminals that are electrically connected to an external device.

  As shown in FIGS. 2 and 3, the clad plate 2b welded to the sealing plate 2a is electrically connected to the positive-side land of the circuit board 5 through the positive-electrode lead plate 8 having a U-shaped cross-section as a positive-electrode terminal. ing. The negative terminal 2 c is configured to be electrically connected to the negative land on the circuit board 5 through the protection element 6. In this way, the long circuit board 5 is disposed so as to face the sealing plate 2a of the unit cell 2, and the positive electrode lead plate 8 and the protective element 6 are disposed between the circuit board 5 and the sealing plate 2a. And are arranged. Although not shown, the positive-side land and the negative-side land of the circuit board 5 are provided on the surface of the circuit board 5 that faces the sealing plate 2a.

  The battery core shown in FIG. 3 is electrically connected as follows. A positive side land (not shown) of the circuit board 5 and the positive lead plate 8 are electrically connected by spot welding. The protective element 6 includes a terminal side lead plate 6B and a substrate side lead plate 6A that are electrically connected to the element body. The protection element 6 is disposed on the sealing plate 2a via the insulating cover 7 so as to be adjacent to the negative electrode terminal 2c. The terminal side lead plate 6B of the protection element 6 is electrically connected to the negative electrode terminal 2c by spot welding, and the substrate side lead plate 6A is electrically connected to the negative electrode side land (not shown) of the circuit board 5 by spot welding. . Similarly to the positive electrode lead plate 8, the substrate side lead plate 6 </ b> A of the protection element 6 has a U shape in cross section. The positive electrode lead plate 8 and the substrate side lead plate 6A of the protection element 6 are planar lead plates when spot welded to the positive electrode side land and the negative electrode side land of the circuit board 5, respectively. Further, the circuit board 5 is disposed adjacent to the sealing plate 2a, and the positive electrode lead plate 8 and the board-side lead plate 6A of the protection element 6 are spot welded to each land of the circuit board 5, and then the circuit board 5 is sealed. The battery core of FIG. 3 is formed by folding back so as to face the plate 2a.

  After the battery core of FIG. 3 is formed, the cap 4 having a bottomed cylindrical shape is arranged so as to cover the sealing plate 2a and the circuit board 5, and the opening periphery of the cap 4 covers the outer edge of the unit cell 2. Covering. In a state where the cap 4 is disposed in the battery core, the label 3 is attached so as to cover the outer surface of the unit cell 2. Since the label 3 is attached to the opening periphery of the cap 4 that covers the outer edge of the unit cell 2, the cap 4 and the unit cell 2 are joined by the label 3.

  The cap 4 is provided with a terminal window 41 and a test terminal window 42 corresponding to the external connection terminals 5A and the test terminals 5T of the circuit board 5. The test terminal window 42 is attached with a submergence determination label 5TL after inspection before shipment so that the test terminal 5T is not exposed.

  In the present embodiment, the circuit board 5 and the cap 4 are arranged on the surface provided with the sealing plate 2a, but particularly on the bottom surface of the outer can or the side surface adjacent to the bottom surface other than the surface provided with the sealing plate 2a. In this case, the shape of the lead plate used for connection between the negative electrode terminal 2c of the unit cell 2 and the circuit board 5 becomes long.

3, Configuration of Label 3 of Battery Pack 1 In the battery pack 1 in the present embodiment shown in FIG. 1, the label 3 is attached so as to wind the outer surface of the unit cell 2 from the width direction. That is, in the battery core shown in FIG. 3, the label 3 is attached so that the outer surface of the unit cell 2 is wound from the width direction. The label 3 fixes the cap 4 disposed on the sealing plate 2a side of the unit cell 2 and the unit cell. Further, the label 3 includes a plurality of projecting pieces 3T projecting from the longitudinal edge of the label 3 so as to cover the sealing plate 2a of the unit cell and a part of the end surface facing the sealing plate 2a. Since one of the pieces 3T is attached so as to cover the outer surface of the cap 4 disposed on the unit cell 2, the adhesive strength between the cap 4 and the unit cell 2 is improved. Further, among the plurality of protruding pieces 3T, a protruding piece 3T that is not provided with the adhesive material 3D is provided, and the protruding piece 3T that is not provided with the adhesive material 3D is exposed on the outer surface of the label 3. By being arranged, as shown in FIG. 1, it has a function as a take-out label 3L.

4 is a partially enlarged cross-sectional view of the label 3 shown in FIG. 4, which is the same as the label 3 provided with the swollen detection portion 3 </ b> C in the cross-sectional view taken along the line AA in the width direction of the battery pack 1 shown in FIG. 1. A sectional view with the battery 2 is shown, and shows a state before the unit cell 2 expands. In addition, about the cross section of the unit cell 2, the positive / negative electrode group, the non-aqueous electrolyte, etc. are abbreviate | omitted for convenience. As shown in FIG. 4, the label 3 is a protective layer 3 </ b> B laminated as a main component on the surface layer of the base material layer 3 </ b> A and the base material layer 3 </ b> A via an adhesive material 3 </ b> D. The base material layer 3A, the protective layer 3B, the base material layer 3A, and the outer surface of the unit cell 2 are fixed by being laminated via an adhesive material 3D. Further, the base layer 3A is formed with a notch penetrating in the thickness direction of the base layer 3A, and this notch functions as a swollen detection portion 3C. In this embodiment, the swelling detection unit 3C is a notch penetrating the base material layer 3A, but it is not particularly limited to this structure. When the unit cell 2 expands, the swelling detection unit 3C breaks into the swelling detection unit 3C. It is only necessary that a cut to such an extent that 3S occurs is provided in the surface layer of the base material layer 3A. Further, when the swelling detection unit 3C is cut so as not to penetrate the base material layer 3A, when the unit cell 2 expands, the warp detection unit 3C recognizes the state in which the swelling detection unit 3C of the base material layer 3A has become thin. It can be performed. Even in a state where the base material layer 3A of such a swelling detection unit 3C is extremely thin, the protective layer 3B covers the swelling detection unit 3C, thereby preventing an external short circuit due to the outer surface of the unit cell 2, The safety of the battery pack 1 can be ensured.

FIG. 5 is a partially enlarged cross-sectional view of the cross section taken along the line AA of the battery pack shown in FIG. 1 in a state where the battery is expanded. Originally, the outer surface of the expanded unit cell has a partially curved shape, but in FIG. 5, for convenience, the outer surface of the unit cell is shown by a straight line. Also, in FIG. 8, the outer surface of the unit cell is shown by a straight line for convenience as in FIG. 5.
The swelling detector 3C shown in FIG. 5 is in a state in which the tear 3S is generated by spreading in the horizontal direction due to the stress generated when the unit cell 2 swells. Therefore, the swelling detection part 3C in which the tear 3S shown in FIG. 5 is generated is in a state where the outer surface of the unit cell 2 or the outer surface of the unit cell 2 with the adhesive material 3D partially attached is exposed, and the user can By visually observing the outer surface of the unit cell 2 from the tear 3S, the degradation of the unit cell 2 can be easily determined. Further, as shown in FIG. 5, also in the swollenness detection unit 3C in a state in which such a tear 3S has occurred, the protective layer 3B completely covers the tear 3S, and the unit cell exposed from the tear 3S The outer surface of the battery pack 1 is prevented from being opened with respect to the outer surface of the battery pack 1.

  Furthermore, since the protective layer 3B of the label 3 is made of a permeable material while preventing the outer surface of the unit cell 2 from being exposed, the state of the swelling detection unit 3C can be accurately observed. The transmittance in the protective layer 3B is preferably one having a transmittance of 50% to 100%, but is not limited to this value, and the state in which the state of the swelling detection unit 3C can be confirmed through the protective layer 3B. If it is enough.

Further, the protective layer 3B of the label 3 is made of a material that stretches so as to correspond to the swelling of the unit cell 2, and the most suitable material is a stretchable material such as made of PET (polyethylene terephthalate) or PP (polypropylene). Those made of a resin having high properties are preferred. In this embodiment, the thickness is about 25 μm. Further, the material of the base material layer 3A is preferably made of a resin having a high elasticity such as a product made of PET (polyethylene terephthalate) or PP (polypropylene) like the protective layer 3B, and has a thickness of about 25 μm.
Further, an adhesive such as an acrylic resin is used as the adhesive material for fixing the base layer 3A and the protective layer 3B and the base layer 3A and the outer surface of the unit cell 2 together. The thickness of each adhesive is about 20 μm, and the thickness of the label 3 is about 90 μm. However, since a dimensional error occurs in the thickness of the adhesive, the maximum thickness is assumed to be about 100 μm.

  As shown in FIG. 1, the swelling detection unit 3 </ b> C provided on the base material layer 3 </ b> A of the label 3 is located at the center of the large surface of the unit cell 2. This is because when the unit cell 2 expands, the central portion of the flat surface of the unit cell 2 is deformed the most, so that the swollen detection portion 3C of the label 3 is arranged so as to cover the central portion of the flat surface of the unit cell 2. Thus, the stress on the swelling detection unit 3C is efficiently applied, and the swelling detection unit 3C functions effectively.

As shown in FIGS. 1 and 2, the swelling detection unit 3 </ b> C is cut into the base material layer 3 </ b> A so as to form a cross shape in a plan view. However, the shape of the swollenness detection unit 3C may be other than a cross shape, and may be a plurality of line segments provided radially from the center of the flat surface of the unit cell 2 to which it is attached.

  FIG. 6 shows a state in which the battery pack 1 of this embodiment is mounted in the battery pack storage space of the electronic device 9. As shown in FIG. 6, in a state where the battery pack 1 is mounted on the electronic device 9, the swelling detection unit 3 </ b> C of the battery pack 1 is located on the opposite side of the surface facing the electronic device 9. That is, since it is located on the outer surface side of the electronic device 9, when the battery pack carver (not shown) of the electronic device 9 is removed, the swelling detection unit 3 </ b> C of the battery pack 1 is removed without removing the battery pack 1. It can be visually recognized.

  The battery pack according to the present invention can be widely used as a main power source or a backup power source for portable electronic devices such as a notebook computer, a mobile phone, a PDA, a tablet, a portable DVD player, a portable GPS, and a transceiver. Alternatively, it can be used as a main power source for a power assist bicycle.

DESCRIPTION OF SYMBOLS 1 ... Battery pack 2, 21 ... Unit cell 2a ... Sealing plate 2b ... Cladding plate 2c ... Negative electrode terminal 3, 31 ... Label 3A ... Base material layer 3B ... Protection layer 3C, 31C ... Swelling detection part 3D ... Adhesive material 3S, 31S ... tear 3T ... protruding piece 3L ... take-out label 4 ... cap 41 ... terminal window 42 ... test terminal window 5 ... circuit board 5A ... external connection terminal 5T ... test terminal 5TL ... submergence determination label 6 ... protective element 6A … Board side lead plate 6B… Terminal side lead plate 7… Insulation cover 8… Positive lead plate 9… Electronic equipment

Claims (2)

Unit cells,
In a battery pack comprising a label attached to the outer surface of the unit cell,
The label has a base material layer provided with a swollen detection part cut out from a surface layer, and one surface of the base material layer is adhered to the outer surface of the unit cell via an adhesive material, and the base A battery pack, wherein a permeable protective layer is attached to the other surface of the material layer via an adhesive material, and the protective layer covers at least a portion facing the swollen detection portion. 2. The electronic device according to claim 1, wherein in the state where the battery pack according to claim 1 is disposed in the electronic device, the swelling detection unit is located on the opposite side of the surface facing the electronic device.

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