JP2018085202A - Battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery pack in which collapse of electric cells is restrained.SOLUTION: A battery pack 10 where multiple rechargeable electric cells 20 are arranged in a prescribed direction while being connected electrically includes a pair of end plates 30A, 30B placed, respectively, at the opposite ends in the arrangement direction A of the multiple electric cells 20, and a restraint band 32 fastened on the upper surface of the pair of end plates 30A, 30B by means of the pair of end plates 30A, 30B, and bridged in the arrangement direction A of the multiple electric cells 20 thus restraining them. The restraint band 32 has an insertion hole 34 for inserting a fastener 38. The insertion hole 34 is a long hole elongating in the arrangement direction A of the electric cells 20.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an assembled battery in which a plurality of chargeable / dischargeable cells are electrically connected.

  Lithium ion secondary batteries, nickel hydride batteries and other secondary batteries that are lightweight and provide high energy density are used as unit cells, and a battery pack that consists of a plurality of unit cells connected in series provides high output. As a power source to be used, it is preferably used as a vehicle-mounted power source or a personal computer and a portable terminal. For example, in Patent Document 1, as an example of a vehicle-mounted assembled battery, a plurality of rectangular cells are arranged and a positive electrode terminal and a negative electrode terminal provided on each single cell are connected in series. A battery is disclosed.

JP 2006-072107 A

  By the way, an assembled battery mounted on a vehicle such as an automobile is assumed to be used in a state in which vibration is generated in addition to limiting the mounting space. An assembled battery (that is, a state in which the individual cells are fixed to each other) is constructed. In such an assembled battery, for example, as shown in FIG. 6, a pair of end plates 2 are installed on the outermost side (both end faces) of a group of unit cells arranged in a stacking direction (array direction) A of unit cells, By fastening the restraint band 3 so as to bridge between the pair of end plates 2 (so as to be bridged in the arrangement direction A of the plurality of unit cells 1), the plurality of unit cells 1 are restrained in the arrangement direction A. Yes.

  However, in such an assembled battery, as shown in FIG. 7, when a load P is applied in the width direction W of the unit cells 1 (a direction orthogonal to the arrangement direction A of the unit cells 1 in a top view), each unit cell 1 is restrained. Since it was restrained by the band 3, the load P could not be released, and there was a problem that the unit cell 1 was easily crushed. The present invention solves the above problems.

  The assembled battery provided by the present invention is an assembled battery in which a plurality of chargeable / dischargeable cells are electrically connected and arranged in a predetermined direction. The assembled battery includes a pair of end plates respectively disposed at both ends in the arrangement direction of the plurality of unit cells, and fastened to a top surface of the pair of end plates by a fastener, and extends in the arrangement direction of the plurality of unit cells. And a restraining band that restrains the plurality of single cells. The restraint band has an insertion hole through which the fastener is inserted. The insertion hole is a long hole extending along the arrangement direction of the unit cells. According to such a configuration, the load applied in the width direction of the unit cells (direction orthogonal to the arrangement direction of the unit cells in the top view) can be released by moving the unit cells, and the unit cells can be made difficult to be crushed.

  In this specification, the “unit cell” is a term indicating individual storage elements that can be connected in series to form an assembled battery, and includes batteries and capacitors having various compositions unless otherwise specified. . The “secondary battery” generally refers to a battery that can be repeatedly charged, and includes so-called storage batteries such as lithium ion secondary batteries and nickel metal hydride batteries. The electric storage element constituting the lithium ion secondary battery is a typical example included in the “unit cell” referred to herein, and a lithium ion secondary battery pack including a plurality of such unit cells is disclosed herein. This is a typical example of an “assembled battery”.

It is a top view which shows typically the structure of the assembled battery which concerns on one Embodiment. It is a top view which shows typically the restraint band which concerns on one Embodiment. It is a side view which shows typically the restraint band which concerns on one Embodiment. It is a top view which shows typically the structure of the assembled battery which concerns on one Embodiment. It is a top view which shows typically the structure of the assembled battery used in the Example. It is a top view which shows the structure of the conventional assembled battery typically. It is a top view which shows the structure of the conventional assembled battery typically.

  Hereinafter, preferred embodiments of the present invention will be described. Note that matters other than matters specifically mentioned in the present specification and necessary for the implementation of the present invention can be grasped as design matters of those skilled in the art based on the prior art in this field. The present invention can be carried out based on the contents disclosed in this specification and common technical knowledge in the field. In addition, each drawing is drawn typically and does not necessarily reflect a real thing. Each drawing shows only an example, and each drawing does not limit the present invention unless otherwise specified.

  The assembled battery disclosed herein may be an assembled battery formed by arranging single cells (typically, single cells having a flat outer shape), and the configuration of the single cells is not particularly limited. Although not intended to be particularly limited, the present invention will be described in detail below using an example of an assembled battery in which a flat lithium ion secondary battery is a single battery and a plurality of the single batteries are connected in series. Explained.

  The configuration of the assembled battery 10 of the present embodiment will be described with reference to FIG. FIG. 1 is a top view schematically showing the configuration of the assembled battery 10 of the present embodiment.

  The assembled battery 10 is configured by connecting a plurality of chargeable / dischargeable cells 20 in series. In the illustrated example, three unit cells 20 (20A, 20B, 20C) having the same shape are arranged in series. In addition, the code | symbol A in drawing shows the arrangement direction of a single cell (thickness direction of a single cell), and the code | symbol W has shown the width direction (direction orthogonal to an arrangement direction in top view) of a single cell.

  The unit cell 20 includes an electrode body (not shown) including a positive electrode and a negative electrode, and a container 50 that houses the electrode body and an electrolyte. The electrode body of the present embodiment is composed of predetermined battery constituent materials (active materials for positive and negative electrodes, current collectors for positive and negative electrodes, separators, etc.) as well as single cells equipped in typical assembled batteries. Yes. Here, a flat wound electrode body is used as the electrode body. The electrode body is not limited to a wound electrode body, and may be, for example, a laminated electrode body in which positive and negative electrodes are alternately and repeatedly laminated via a separator.

  The container 50 of the present embodiment has a shape (box shape in the illustrated example) that can accommodate a flat wound electrode body. The material of the container 50 is not particularly limited as long as it is the same as that used for a typical unit cell, but from the viewpoint of reducing the weight of the assembled battery itself, for example, a thin metal or synthetic resin container Can be used.

  On the upper surface of the container 50, a positive electrode terminal (not shown) electrically connected to the positive electrode of the wound electrode body and a negative electrode terminal (not shown) electrically connected to the negative electrode are provided. And between the adjacent unit cells 20, one positive terminal and the other negative terminal are electrically connected by an inter-terminal connector (not shown). Thus, the assembled battery 10 of the desired voltage is constructed | assembled by connecting each cell 20 in series.

  The single cells 20 disclosed herein are arranged and restrained in a predetermined direction A. Specifically, the plurality of unit cells 20 are arranged in a reversed manner one by one so that the respective positive electrode terminals (not shown) and negative electrode terminals (not shown) are alternately arranged. The side walls (the wide surface of the container 50, that is, the surface corresponding to the flat surface of the wound electrode body housed in the container 50) are arranged in an opposing direction.

  A restraining member that restrains the plurality of unit cells 20 together is disposed around the arranged unit cells 20. That is, a pair of end plates 30 </ b> A and 30 </ b> B are disposed at both ends in the arrangement direction A of the plurality of unit cells 20 (further outside the unit cells 20 located on the outermost side). Further, a restraining band 32 is attached to the pair of end plates 30A, 30B so as to bridge the pair of end plates 30A, 30B. In this embodiment, the two restraining bands 32 are attached so as to bridge the pair of end plates 30A, 30B at two locations on both sides in the width direction W. The restraint band 32 spans the arrangement direction A of the plurality of unit cells 20 to restrain the plurality of unit cells 20. Further, the restraining band 32 is fastened to the upper surfaces of the end plates 30A and 30B by a fastener 38. In this embodiment, the fastener 38 is a bolt 38 and a nut (not shown). Bolts 38 for attaching the restraining band 32 are provided on the upper surfaces of the end plates 30A and 30B. The bolt 38 extends upward from the upper surfaces of the end plates 30A, 30B.

  FIG. 2 is a top view (plan view) of the restraining band 32. FIG. 3 is a side view of the restraining band 32. As shown in FIGS. 1 to 3, the restraining band 32 is a band-like member and is made of a material that does not break when restraining (for example, iron, typically an iron material that has been subjected to a corrosion-preventing surface coating treatment). Yes. The restraining band 32 is formed with an insertion hole 34 for fastening the restraining band 32 to the end plates 30A and 30B. Here, the bolts 38 provided on the upper surfaces of the end plates 30 </ b> A and 30 </ b> B are inserted into the insertion holes 34. In this embodiment, the insertion holes 34 are provided at two locations on both sides in the arrangement direction A of the restraining band 32. The two insertion holes 34 are provided in alignment with bolts 38 provided on the upper surfaces of the end plates 30A and 30B. The restraining band 32 is disposed along the upper surfaces of the end plates 30A and 30B and the unit cell 20, and through holes 34 are attached to bolts 38 extending upward from the end plates 30A and 30B, and are fastened and fixed by nuts (not shown). . The tightening torque of the nut is not particularly limited, but may be set to 2 N / m to 5 N / m (typically 3 ± 0.5 N / m), for example.

  In the technique disclosed herein, the insertion hole 34 of the restraining band 32 is a long hole extending along the arrangement direction A of the unit cells 20. In other words, the insertion hole 34 has a length L1 (FIG. 2) in the arrangement direction A longer than a length L2 (FIG. 2) in the width direction W orthogonal to the arrangement direction A in a top view. The length L1 in the arrangement direction A of the insertion holes 34 is not particularly limited as long as it is longer than the length L2 in the width direction W (that is, L1> L2). The length L1 in the arrangement direction A is suitably 16 mm or more, for example.

  In a preferred embodiment, the length L1 of the insertion holes 34 in the arrangement direction A is a length of √51 / 10 times or more with respect to the width w2 (FIG. 1) of the unit cells 20 in the width direction W. That is, the ratio (L1 / w2) of the length L1 in the arrangement direction A of the insertion holes 34 to the width w2 in the width direction W of the unit cell 20 satisfies (L1 / w2) ≧ √51 / 10. By using the restraining band 32 having the insertion hole 34 having such a length L1, the collapse of the unit cell 20 can be better suppressed. In the technique disclosed herein, for example, the relationship between L1 and w2 is (L1 / w2) ≧ √51 / 8, more preferably (L1 / w2) ≧ √51 / 6, and even more preferably (L1 / w2). ) ≧ √51 / 5 can be preferably implemented. Note that √51 means the square root (root) of “51”.

  In a preferred embodiment disclosed herein, the interval w1 (FIG. 1) between the two restraining bands 32 is longer than 0.3 times the width w2 of the unit cell 20 in the width direction W. That is, the ratio (w1 / w2) of the interval w1 between the two restraining bands 32 to the width w2 in the width direction W of the unit cell 20 satisfies (w1 / w2)> 0.3. In the width direction W, by setting the distance w1 between the two restraining bands 32 with respect to the width w2 of the unit cell 20 as described above, the collapse of the unit cell 20 can be better suppressed. For example, the technique disclosed herein can be preferably implemented in a mode in which the relationship between w1 and w2 is, for example, (w1 / w2) ≧ 0.32, typically (w1 / w2) ≧ 0.35. . Although the upper limit of (w1 / w2) is not particularly limited, it may normally be (w1 / w2) ≦ 0.6, typically (w1 / w2) ≦ 0.5.

  FIG. 4 shows a state in which a crushing test in which a load P is applied to the unit cell 20 along the width direction W is performed on the assembled battery 10 constrained by the end plates 30A and 30B and the restraining band 32 described above. . In this battery pack 10, the insertion holes 34 of the restraining band 32 extend along the arrangement direction A of the unit cells 20, and the length L1 (FIG. 2) in the arrangement direction A is the length L2 in the width direction W (FIG. 2). ) Longer than. Therefore, the fastener (here, the bolt provided on the upper surface of the end plates 30A and 30B) 38 inserted through the insertion hole 34 is restricted in movement (displacement) in the width direction W within the insertion hole 34. Movement in the arrangement direction A is allowed to some extent. Therefore, when a load P in the width direction W is applied to the unit cells 20, the fasteners 38 move (displace) in the arrangement direction A within the insertion holes 34 as shown in FIG. (Typically shifted obliquely), and the load applied to the single electrical ground 20 can be released. As a result, the unit cells 20 are less likely to be crushed, and the amount of collapse of each unit cell 20 in the above-described crush test can be reduced as compared to the conventional case.

  In order to confirm the effect of using the restraining band 32, the following test was performed. That is, as shown in FIG. 5, a unit cell stack in which three unit cells 20 and four spacers 40 are alternately arranged, and a pair disposed at both ends in the arrangement direction A of the unit cell stack, respectively. An assembled battery comprising the end plates 30A and 30B and a restraining band 32 fastened by bolts and nuts to the upper surfaces of the pair of end plates 30A and 30B so as to bridge between the pair of end plates 30A and 30B was constructed. . The fastening torque of the bolt and nut was adjusted to 3 N / m.

  The restraint band 32 has an insertion hole 34 through which the bolt 38 (FIG. 1) is inserted. In the embodiment, the insertion hole 34 of the restraining band 32 has a length L1 (FIG. 2) in the arrangement direction A longer than a length L2 (FIG. 2) in the width direction W. Here, the length L1 of the insertion holes 34 in the arrangement direction A is √51 / 5 times the width w2 (FIG. 1) of the unit cells 20 in the width direction W. On the other hand, in the comparative example, the insertion hole 34 of the restraining band 32 has a length L2 in the width direction W longer than a length L1 in the arrangement direction A. The length L2 in the width direction W was the same in the example and the comparative example.

  For the assembled batteries of the example and the comparative example, a crushing test in which a load P of 200 kN at the maximum was applied to the unit cell 20 along the width direction W was performed five times each. Moreover, the presence or absence of heat generation of the unit cell during the crushing test was confirmed. As a result, for the assembled battery of the comparative example, the unit cell 20 was crushed in all of the five crush tests, and the unit cell 20 generated heat. On the other hand, in the assembled battery of the example, the crushing of the unit cell 20 was suppressed as compared with the comparative example, and no heat generation was observed. From this result, it was confirmed that by using a restraining band having an insertion hole extending in the arrangement direction A, it is possible to realize an assembled battery that can reduce the collapse amount of the unit cell during the collapse test.

  As mentioned above, although the specific example of this invention was demonstrated in detail, these are only illustrations and do not limit a claim. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

  The assembled battery 10 disclosed herein is suitable as a power source mounted on a vehicle, for example, because the collapse of each unit cell is suppressed and high performance can be exhibited. Therefore, the assembled battery 10 disclosed herein can be suitably used as a power source (typically a driving power source) for a motor mounted on a vehicle including an electric motor such as a hybrid vehicle or an electric vehicle.

10 assembled battery 20 single cell 30A, 30B end plate 32 restraint band 34 insertion hole 38 fastener 50 container

Claims (1)

A battery pack in which a plurality of chargeable / dischargeable cells are electrically connected and arranged in a predetermined direction,
A pair of end plates respectively disposed at both ends in the arrangement direction of the plurality of unit cells;
A fastening band fastened by a fastener to the upper surfaces of the pair of end plates, and spanned in the arrangement direction of the plurality of unit cells to restrain the plurality of unit cells;
The restraint band has an insertion hole through which the fastener is inserted,
The insertion hole is an assembled battery which is a long hole extending along the arrangement direction of the unit cells.

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