JP2006185756A - Battery pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery pack compactly formable while having high flame resistance. <P>SOLUTION: This battery pack is composed by housing a battery formed by housing an electrode plate group and an electrolyte in a metallic battery case and having connection electrodes on its one end face, and a circuit board having a charge-discharge protection circuit connected to the connection electrodes and external connection terminals in a housing case having a window part for exposing the external connection terminals to the outside. In the battery pack, the housing case 2 is composed by jointing an upper case 11 to a lower case 12; the main parts of the upper case 11 and the lower case 12 are formed with metal cases 13 and 15 each formed of a metal plate, respectively; the joint parts of the upper case 11 and the lower case 12 are formed with insert-molded resin joint parts 14 and 16 of a flame-resistant resin; and a joining part of the upper case 11 and the lower case 12 is formed of a resin joining part 18 of a flame-resistant resin simple body. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a battery pack in which a battery, a circuit board having a charge / discharge protection circuit and an external connection terminal are housed in a housing case.

  In a battery pack in which a battery and a circuit board having a charge / discharge protection circuit are housed and integrated in a housing case, the battery pack is required to have a predetermined flame retardancy along with being lightweight and compact. Has been.

  As a conventional battery pack, a battery and a circuit board that are housed in a synthetic resin housing case are known, and the housing case is made of a flame retardant resin in order to make the battery pack flame retardant. It is also known to do.

  On the other hand, the battery case is made of a laminate case material, and the battery case is housed in a housing case in which the resin frames of the upper case and the lower case formed by insert molding of the resin frame on the periphery of the aluminum plate are joined, And what provided the concave-shaped or convex-shaped reinforcement part in the aluminum plate is known (for example, refer patent document 1).

  Further, a similar laminated battery and circuit board are accommodated in an accommodation case formed by combining the first and second cases, and the first and second cases are made of a resin frame and an insert in the resin case. It is known that it is made of a metal plate integrated by molding, and a side edge that enables insert molding is formed on the periphery of the metal plate by bending or drawing. As the resin, a resin composition comprising a thermoplastic resin such as polycarbonate or liquid crystal polymer and a glass fiber chop or glass bead is used to ensure dimensional accuracy and strength, and the thickness of the metal plate is 0.05 to 0. The thickness of the .25 mm resin frame is 0.6 to 1.5 mm when the metal plate is 0.1 mm (see, for example, Patent Document 2).

In addition, in a battery pack in which a similar laminated battery is housed in a housing case formed by welding or bonding the first and second cases made of synthetic resin, a stainless steel reinforcing plate is attached to the surface of the battery pack. There is known one that is attached to improve rigidity (for example, see Patent Document 3).
JP 11-176400 A JP 2001-93495 A JP 2001-307703 A

 By the way, even if the conventional battery pack housing case is made of flame-retardant resin, it satisfies V94 level or higher of UL94 standard (Tests for Flammability of Plastic Materials for Parts in Devices and Appliances) In order to do this, it is necessary to make the thickness of the storage case about 3.2 mm or more, and the thickness of the storage case becomes thick, which is a problem against the downsizing of the battery pack.

  Moreover, in the structure of patent document 1 and patent document 3, although the subject of ensuring a flame retardance and the structure for it are not described, according to the structure of the storage case, the flame retardance in the metal plate arrangement | positioning surface is No problem at all. However, since the peripheral side wall of the housing case is made only of a resin frame, it is necessary to increase its thickness in order to ensure flame resistance as well as strength. As a result, the battery pack can be made more compact. There is a problem that there is a limit.

  In the configuration of Patent Document 2, neither the problem of ensuring flame retardancy nor the configuration for that purpose is described, and side edges are formed on the periphery of the metal plate by bending or drawing, and are integrated into the frame. Although it is embedded, it is as long as it is necessary for insert molding, and does not suggest a technique of forming a case including a frame body with a metal plate, and is basically the same as Patent Document 1 and Patent Document 3 above. There is a problem.

  In view of the above-described conventional problems, an object of the present invention is to provide a battery pack that can be configured compactly while having high flame retardancy.

  The battery pack of the present invention comprises a battery group and an electrolytic solution in a metal battery case, a battery having a connection electrode on one end face thereof, a charge / discharge protection circuit connected to the connection electrode, and an external connection In a battery pack in which a circuit board having terminals is housed in a housing case having a window that exposes external connection terminals to the outside, the housing case is formed by joining an upper case and a lower case, Each of the lower cases is composed of a metal case made of a metal plate, and its main part is composed of a resin-joined part of a flame-retardant resin alone formed by insert molding.

  According to this configuration, in the battery pack in which a battery having a metal battery case is housed in the housing case, the housing case is configured by the upper case and the lower case, the main part of which is a metal case. The resin joint for joining the upper case and the lower case, which has flammability and does not have a metal case, is made of flame-retardant resin. By minimizing it to the minimum, flame retardance can be ensured even if the thickness of the resin joint portion is reduced, and therefore a compact configuration can be achieved while having high flame retardancy.

  In addition, the thickness t of the resin joined portion is set to be as thin as 0.5 mm to 1.0 mm for compactness, and the distance d between the metal case edges of the upper case and the lower case is set to 1.0 t ≦ d. It is preferable that ≦ 4.0t. If d <1.0t, there is a possibility that the bonding by the resin bonding portion becomes unstable. If d> 4.0t, the width of the single resin portion is large. In such a case, since the reliability with respect to flame retardancy is inferior, by defining the distance d between the metal case edges with respect to the thickness t of the resin joint in this way, the thickness of the resin joint The desired flame retardance can be secured while reducing the thickness of the material and reducing the size.

  In addition, as the flame retardant resin constituting the resin joint portion, it is possible to use a resin in which one kind of resin selected from polycarbonate resin, ABS resin, polycarbonate-ABS polymer alloy, polystyrene resin, and polyphenylene sulfite is made flame retardant. Is preferred.

  According to the battery pack of the present invention, since the main part of the housing case is composed of a metal case, it has high flame retardancy as a whole, and the resin joint where there is no metal case is composed of flame retardant resin. Because it is configured, by making the width dimension of the flame retardant resin alone the minimum necessary for bonding, high flame resistance can be ensured even if the thickness of the resin bonded portion is reduced, and high A battery pack that achieves both flame retardancy and compactness can be realized.

  Hereinafter, an embodiment of a battery pack of the present invention will be described with reference to FIGS.

  1 and 2, reference numeral 1 denotes a flat rectangular parallelepiped battery pack, in which a battery 3 and a circuit board 4 are housed in a housing case 2. The battery 3 has a rectangular shape with a flat cross-sectional shape, or a rounded rectangular or oval rectangular outer shape, and is configured to accommodate an electrode plate group and an electrolyte as a power generation element inside a metal battery case, A connecting electrode (not shown) of a positive electrode and a negative electrode is disposed on one end face. In the present embodiment, the battery 3 is composed of a lithium ion battery, and the electrode plate group is configured to be laminated in multiple layers by winding with a separator interposed between a belt-like positive electrode plate and a negative electrode plate. The positive electrode plate is made by applying and drying a positive electrode mixture to a core material made of aluminum foil, and the negative electrode plate is made by applying and drying a negative electrode mixture to a core material made of copper foil, and the separator is microporous. It is composed of a conductive polypropylene film.

  The circuit board 4 is fitted and engaged with a board placement portion 5 formed on the inner surface side of the one end face 2 a of the storage case 2 and is disposed in the vicinity of one end face of the battery 3, and is connected to a connection electrode on one end face of the battery 3. It has a connected charge / discharge safety circuit and three external connection terminals 6. Of the three external connection terminals 6, two are positive and negative external connection terminals, and the remaining one is a connection terminal for detecting identification resistance. A window 7 that exposes the external connection terminal 6 to the outside is opened at one end surface 2 a of the storage case 2.

  As shown in FIG. 3, the housing case 2 is configured by joining a rectangular dish-shaped upper case 11 and a lower case 12. As shown in FIG. 5, the upper case 11 is formed by press-molding a metal case 13 in which bent side pieces 13 b are connected to four sides of a rectangular metal plate 13 a, and insert molding is performed using the metal case 13. 4 and FIG. 3A, a structure in which a resin joint 14 projecting a predetermined amount from the end edge of the bent side piece 13b is integrally provided on the inner and outer surfaces of the bent side piece 13b of the metal case 13. Has been.

  As shown in FIG. 7, the lower case 12 is formed by press-molding a metal case 15 in which bent side pieces 15 b are connected to four sides of a rectangular metal plate 15 a, and insert molding is performed using the metal case 15. 6 and 3 (a), a structure in which a resin joint portion 16 is integrally provided on the inner and outer surfaces of the bending side piece 15b of the metal case 15 so as to protrude a predetermined amount from the edge of the bending side piece 15b. Has been.

  The resin joint 14 of the upper case 11 and the resin joint 16 of the lower case 12 are provided with a fitting projection 14a on the inner peripheral side of the resin joint 14 so as to be soldered to each other. On the inner peripheral side of the joint portion 16, a fitting concave step portion 16a into which the fitting protrusion 14a is fitted is formed. Further, in order to improve the hermetic bondability of the resin joints 14 and 16, the tip edge of the fitting protrusion 14a is formed at the pointed protrusion 14b, and the protruding piece protrudes upward from the inner peripheral edge of the fitting concave step 16a. 16b is formed.

  In addition, on one side wall of the upper case 11 forming the one end surface 2a of the housing case 2, as shown in FIG. 4, a notch portion 17 is formed in the resin joint portion 14 corresponding to the window portion 7, and Correspondingly to the bent side piece 13b of the metal case 13, a notch 13c is formed as shown in FIG. Further, on one side wall of the lower case 12, as shown in FIG. 6, a window portion 7 is formed in the resin joint portion 16, and the bent side piece 15 b of the metal case 15 is correspondingly shown in FIG. 7. A notch 15c is formed in the upper surface.

  For the metal cases 13 and 15 of the upper case 11 and the lower case 12, a stainless steel plate or an aluminum alloy plate having a thickness of 0.10 mm to 0.30 mm, preferably 0.15 mm to 0.25 mm is preferably used. Used. Further, if the peripheral side walls of the upper case 11 and the lower case 12 are formed by bending press working as in the present embodiment, it is preferable because the productivity is high, but they can also be formed by drawing.

The resin joints 14 and 16 of the upper case 11 and the lower case 12 are made of a flame retardant synthetic resin. As the flame retardant synthetic resin, a flame retardant polycarbonate resin is preferably used, and one kind of resin selected from ABS resin, polycarbonate-ABS copolymer, polystyrene resin, and polyphenylene sulfite is flame retardant. Resin etc. can also be used. Further, the thickness t of the resin joints 14 and 16 is in the range of 0.5 mm to 1.0 mm, preferably 0.5 mm to 0.8 mm. Flame retardant methods include bromine compounds such as decabromodiphenyl oxide (DBDPO) and tetrabromobisphenol A (TBBPA) and antimony trioxide (Sb ₂ O ₃ ) in combination with a synergistic effect, tricresyl phosphate (TCP), phosphate ester flame retardants such as tri-n-butyl phosphate (TBP), triphenyl phosphate (TPP), magnesium hydroxide (Mg (OH) ₂ ), aluminum hydroxide (Al (OH) _Although there is a non-halogen flame retardant method using ₃ ) or the like alone or in combination, it is not particularly limited.

  Then, as shown in FIG. 3A, the upper case 11 is placed on the lower case 12 containing the battery 3 and the circuit board 4, and as shown in FIG. 3B, the upper case 11 and the lower case 12 are covered. The housing case 2 is hermetically bonded by heating the resin bonding portions 14 and 16 by ultrasonic heating, induction heating, or the like to form the battery pack 1.

  In the housing case 2 configured by joining the upper case 11 and the lower case 12, as shown in FIG. 3B, the flame retardant resin alone composed of the resin joint portions 14 and 16 without the metal cases 13 and 15. The resin joint 18 has a thickness t of 0.5 mm to 1.0 mm and a width dimension of 1.0 t ≦ d ≦ 4.0 t.

  According to the battery pack 1 having the above configuration, since the main parts of the upper case 11 and the lower case 12 constituting the housing case 2 are constituted by the metal cases 13 and 15, the overall flame retardancy is high. Have Further, the resin joint portions 14 and 16 for joining the upper case 11 and the lower case 12 where the metal cases 13 and 15 are not present are made of a flame retardant resin, and the resin joint portion 18 of the flame retardant resin alone is formed. The thickness t is reduced to 0.5 to 1.0 mm and the width d is set to 1.0 t ≦ d ≦ 4.0 t, so that the thickness of the resin joint 18 is reduced as described above. Even in such a case, flame retardancy can be ensured, and thus a compact battery pack 1 can be constructed while having high flame retardancy.

  A specific example and the outline of the UL94 standard for flame retardancy test will be described.

Example 1
As shown in FIG. 5, the upper case 11 is formed by press-molding a metal case 13 formed by connecting bent side pieces 13b to four sides of a rectangular metal plate 13a made of a JIS A3003 series aluminum alloy and having a thickness of 0.20 mm. The metal case 13 is formed and insert-molded. As shown in FIGS. 4 and 3A, the inner and outer surfaces of the bent side piece 13b of the metal case 13 are 1.0 mm from the edge of the bent side piece 13b. The projecting flame retardant polycarbonate resin joint 14 is integrally provided.

As shown in FIG. 7, the lower case 12 is formed by press-molding a metal case 15 formed by connecting bent side pieces 15b to four sides of a rectangular metal plate 15a made of a JIS A3003 series aluminum alloy and having a thickness of 0.20 mm. The metal case 15 is formed and insert-molded. As shown in FIGS. 6 and 3A, the inner and outer surfaces of the bent side piece 15b of the metal case 15 are 1.0 mm from the edge of the bent side piece 15b. A flame retardant polycarbonate resin joint 16 made of protruding tetrabromobisphenol A (TBBPA) and antimony trioxide (Sb ₂ O ₃ ) was integrally provided.

  A rectangular lithium ion battery 3 and a circuit board 4 having a flat cross-sectional shape were accommodated in the storage case 2 composed of the upper case 11 and the lower case 12 thus manufactured. The circuit board 4 is fitted and engaged with a board placement portion 5 formed on the inner surface side of the one end face 2 a of the storage case 2 and is disposed in the vicinity of one end face of the battery 3, and is connected to a connection electrode on one end face of the battery 3. The charge / discharge safety circuit and the three external connection terminals 6 are connected.

  Then, as shown in FIG. 3 (b), the resin case 14 and 16 of the upper case 11 and the lower case 12 are ultrasonically heated and welded to each other so that the housing case 2 is hermetically sealed, and the battery pack 1 is attached. The battery pack of Example 1 was configured.

  The thickness t of the resin joints 14 and 16 is 0.50 mm obtained by adding a flame retardant polycarbonate resin having a thickness of 0.15 mm to both ends of the upper and lower cases having a thickness of 0.20 mm. The distance d between the metal case edges was 1.0 mm.

(Example 2)
Flame retardant ABS with resin joints 14 and 16 formed on both ends of an upper and lower case with a thickness of 0.20 mm by decabromodiphenyl oxide (DBDPO) and antimony trioxide (Sb ₂ O ₃ ) with a thickness of 0.40 mm, respectively. A battery bag of Example 2 was fabricated in the same manner as Example 1 except that the resin was added to 1.00 mm and the distance d between the metal case edges of the upper case and the lower case was 1.0 mm.

(Example 3)
The thickness of the resin joints 14 and 16 is 0.50 mm obtained by adding a flame-retardant polycarbonate resin having a thickness of 0.15 mm to both ends of the upper and lower cases having a thickness of 0.2 mm, and the metal case edges of the upper case and the lower case A battery bag of Example 3 was produced in the same manner as Example 1 except that the distance d between them was 2.0 mm.

(Comparative Example 1)
A battery bag of Comparative Example 1 was produced in the same manner as Example 1 except that a flame retardant polycarbonate resin having a thickness of 1.0 mm was used without using metal cases for the upper and lower cases.

(Comparative Example 2)
A battery bag of Comparative Example 2 was produced in the same manner as Example 1 except that a flame retardant polycarbonate resin having a thickness of 1.5 mm was used without using metal cases for the upper and lower cases.

(Comparative Example 3)
The thickness of the resin joints 14 and 16 is 0.50 mm obtained by adding a non-flame retardant polycarbonate resin having a thickness of 0.15 mm to both ends of the upper and lower cases having a thickness of 0.2 mm, and between the metal case edges of the upper case and the lower case. A battery bag of Comparative Example 3 was produced in the same manner as in Example 1 except that the distance d was set to 1.0 mm.

  Table 1 shows the results of evaluation of flame retardancy according to the UL94 standard using the battery packs of Examples 1 to 3 and Comparative Examples 1 to 3 obtained as described above.

The UL94 standard prepares a test sample of n = 5, measures the _first time t ₁ until the combustion flame disappears when the flame is removed after being exposed to a predetermined flame for 10 seconds. After exposure to a predetermined flame for 10 seconds, a second time t ₂ until the combustion flame disappears when the flame is moved away, and a time t ₃ until the red hot state disappears at this time are measured.

The evaluation criteria for the V-0 level are that t ₁ + t ₂ time is within 10 seconds, n = 5 total time is within 50 seconds, t ₂ + t ₃ time is within 30 seconds, and cotton does not burn due to falling flame The evaluation criteria of the V-1 level are that the time of t ₁ + t ₂ is within 30 seconds, the total time of n = 5 is within 250 seconds, the time of t ₂ + t ₃ is within 60 seconds, and cotton does not burn due to falling flame The evaluation criteria for the V-2 level are that the time of t ₁ + t ₂ is within 30 seconds, the total time of n = 5 is within 250 seconds, the time of t ₂ + t ₃ is within 60 seconds, and cotton burns due to falling flame That is acceptable.

  From Table 1, the battery pack according to the present invention has a metal case whose main part of the storage case is made of an aluminum alloy, and only the joint part of the upper and lower cases is made of flame-retardant resin. The battery back that satisfies the −0 level was found to be unable to satisfy the V-1 level when the thickness is 1.0 mm, and cannot be satisfied unless the thickness is equal to or greater than 1.5 mm. . This difference of 0.5 mm is a difference of 1.0 mm between the top, bottom, left and right, which is a big difference in the current situation where compactness is strongly demanded.

  It is also clear that even if the main part of the storage case is a metal case made of an aluminum alloy, the V-2 level cannot be satisfied if only the joint of the upper and lower cases is made of non-flame retardant resin. It was.

  The battery pack of the present invention has a high flame retardance as a whole because the main part of the housing case is composed of a metal case, and the resin joint where the metal case does not exist is composed of a flame retardant resin. Therefore, by minimizing the part of the flame retardant resin that is necessary for bonding, high flame resistance can be secured even if the thickness of the resin bonded part is reduced. Can be realized, and is useful for small battery packs for portable electronic devices.

The whole battery pack perspective view in one embodiment of the present invention. The AA cross-sectional top view of FIG. The detailed structure in the BB line position of FIG. 1 of the storage case of the embodiment is shown, (a) is sectional drawing before joining of an upper case and a lower case, (b) is sectional drawing of the joining state. The upper case of the embodiment is shown, (a) is a front view, (b) is a plan view, (c) is a rear view, and (d) is a side view. The metal case of the upper case of the embodiment is shown, (a) is a front view, (b) is a plan view, (c) is a rear view, and (d) is a side view. The lower case of the embodiment is shown, (a) is a front view, (b) is a plan view, (c) is a rear view, and (d) is a side view. The metal case of the lower case of the embodiment is shown, (a) is a front view, (b) is a plan view, (c) is a rear view, and (d) is a side view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Battery pack 2 Storage case 3 Battery 4 Circuit board 6 External connection terminal 7 Window part 11 Upper case 12 Lower case 13 Metal case 14 Resin joint part 15 Metal case 16 Resin joint part 18 Resin joint part of resin single body

Claims (3)

  A battery having a plate group and an electrolyte contained in a metal battery case, having a connection electrode on one end surface thereof, and a circuit board having a charge / discharge protection circuit connected to the connection electrode and an external connection terminal In the battery pack that is housed in a housing case having a window portion that exposes the external connection terminal to the outside, the housing case is formed by joining the upper case and the lower case, and the upper case and the lower case are each made of a metal plate. A battery pack comprising: a metal case comprising a main portion thereof, and a joint portion formed by a resin joint portion of a flame-retardant resin alone formed by insert molding. The thickness t of the resin joint is 0.5 mm to 1.0 mm, and the distance d between the metal case edges of the upper case and the lower case is 1.0 t <d <4.0 t. The battery pack according to claim 1. The flame-retardant resin constituting the resin joint is a resin obtained by flame-retarding one kind of resin selected from polycarbonate resin, ABS resin, polycarbonate-ABS polymer alloy, polystyrene resin, and polyphenylene sulfite. The battery pack according to claim 1 or 2.

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