JP2012146588A - Battery module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery module capable of improving cooling efficiency while minimizing an increase in capacity of the battery module.SOLUTION: A battery module comprises a plurality of lithium ion secondary batteries which are combined together. Each of the lithium ion secondary batteries has a columnar shape with a pair of bottom and side faces. The side face has a shape of a rectangular column with rounded corners made up of a pair of flat surfaces and a pair of curved surfaces. The battery module is configured such that the flat surfaces of the lithium ion secondary batteries face each other with a gap therebetween, and that the bottom surfaces are aligned to face in the same direction.

Description

  The present invention relates to a battery module, and more particularly to a battery module using a large-capacity lithium ion secondary battery.

  In recent years, hybrid electric vehicles (HEV) have been rapidly spreading from the viewpoint of energy saving and global environmental protection. HEV requires a high-voltage, large-capacity power source to drive an electric motor as a power source, and a large number of single-cell secondary batteries are mounted connected in series and in parallel. Usually, these single cell secondary batteries are used as a battery module in which a plurality are combined.

  For example, Patent Document 1 discloses that a rectangular battery body configured by laminating a plurality of electrodes, a case surrounding the battery body, and a side periphery of the case for fastening with another rectangular battery. And a plurality of rectangular batteries arranged so that the electrode surfaces are parallel to each other, and fastening means for fastening the fastening parts in the plurality of rectangular batteries. A flat battery module is disclosed. According to Patent Document 1, it is not necessary to increase the thickness of the case, and it is said that a rectangular battery module having good volume, weight energy efficiency, space factor, and excellent vibration resistance can be provided.

JP-A-9-219181

  The demand for larger capacity and smaller size (that is, higher energy density) for secondary batteries is increasing, and research and development of lithium ion secondary batteries having higher energy density are being energetically performed. However, the higher the energy density of the lithium ion secondary battery, the greater the heat generated by the charge / discharge reaction of the electrode, and there is concern that the heat may adversely affect the cycle characteristics. In particular, in a battery module in which a plurality of lithium ion secondary batteries are combined, the heat generation of each single cell secondary battery is integrated, so that a heat countermeasure (heat radiation countermeasure) becomes even more important.

  The battery module described in Patent Document 1 places emphasis on space factor and vibration resistance, and does not disclose proposals for measures against heat (heat dissipation measures). On the other hand, there is a problem that cooling cannot be performed efficiently simply by providing a gap between the single cell secondary batteries combined in the battery module. In addition, it is considered that cooling efficiency can be improved when a cooling wind guide (cooling wind) is provided outside the battery module, but the overall volume of the battery module and the guide combined is increased. Therefore, there is a problem that the volume energy density is significantly reduced.

  Accordingly, an object of the present invention is to provide a battery module of a lithium ion secondary battery that can solve the above-described problems and improve cooling efficiency while minimizing an increase in the volume of the battery module.

  In order to achieve the above object, the present invention provides a battery module in which a plurality of lithium ion secondary batteries are combined, each of the lithium ion secondary batteries having a columnar shape including a pair of bottom and side surfaces, The side surfaces have a rounded rectangular prism shape composed of a pair of flat surface portions and a pair of curved surface portions, and the respective flat surface portions of the plurality of lithium ion secondary batteries face each other with a gap therebetween, and Provided is a battery module characterized in that each curved surface portion is arranged to face the same direction.

  ADVANTAGE OF THE INVENTION According to this invention, the battery module of the lithium ion secondary battery which can improve cooling efficiency can be provided, suppressing the volume increase of a battery module to the minimum.

It is a perspective schematic diagram which shows one example of the battery module which concerns on this invention. It is a perspective schematic diagram which shows the external appearance of the lithium ion secondary battery used for this invention. It is a disassembled perspective view which shows an example of schematic structure of the battery module which concerns on this invention. It is a perspective schematic diagram which shows the flow of the cooling air in the battery module which concerns on this invention. It is the front schematic diagram which looked at the flow of the cooling air in the battery module which concerns on this invention from the bottom face direction of the arranged lithium ion secondary battery. It is the side surface schematic diagram which looked at the flow of the cooling air in the battery module which concerns on this invention from the plane part direction of the arranged lithium ion secondary battery.

  As described above, the battery module according to the present invention is a battery module in which a plurality of lithium ion secondary batteries are combined, and each of the lithium ion secondary batteries has a columnar shape including a pair of bottom surfaces and side surfaces. The side surface has a shape of a rounded rectangular prism comprising a pair of flat surface portions and a pair of curved surface portions, and the respective flat surface portions of the plurality of lithium ion secondary batteries face each other with a gap therebetween. And each bottom surface is arranged in the same direction.

Moreover, the following improvements and changes can be added to the battery module according to the present invention.
(1) The radius of curvature of the curved surface portion is a ratio of 1/2 or more and 2/3 or less with respect to the thickness of the lithium ion secondary battery.
(2) The gap is a ratio of 1/15 or more and 1/3 or less with respect to the thickness of the lithium ion secondary battery. (3) A tab plate that closes the bottom surface side of the arranged lithium ion secondary battery. Is further provided.
(4) The plurality of lithium ion secondary batteries are fixed by a positioning member and a frame-shaped case, and the frame-shaped case has a brace.

  Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the embodiments taken up here, and may be improved or combined as appropriate without departing from the scope of the invention.

  First, the lithium ion secondary battery used in the present invention will be described. FIG. 2 is a schematic perspective view showing the appearance of the lithium ion secondary battery used in the present invention. As shown in FIG. 2, the lithium ion secondary battery 1 used in the present invention has a columnar shape including a pair of bottom surfaces 10 and side surfaces 11, and the side surface 11 includes a pair of flat surface portions 12 and a pair of curved surface portions 13. It has the shape of a rounded round prism. In other words, the bottom surface 10 has a columnar shape having a rounded rectangular shape (so-called racetrack shape).

  If the distance between the pair of flat surface portions 12 is the thickness T of the lithium ion secondary battery 1 and the curvature radius of the curved surface portion 13 is R, the curvature radius R is 1/2 to 2/3 of the thickness T. A ratio is preferred. In addition, the direction (left-right direction in FIG. 2) orthogonal to thickness in the bottom face 10 is defined as the width direction, and the direction between the pair of bottom faces 10 (up-down direction in FIG. 2) is defined as the height direction.

  A positive electrode terminal 14 and a negative electrode terminal 15 are provided on the pair of bottom surfaces 10. The positive electrode terminal 14 and the negative electrode terminal 15 are connected to an electrode group inside the lithium ion secondary battery 1 and are charged and discharged. In FIG. 2, the positive electrode terminal 14 and the negative electrode terminal 15 are provided to face the bottom surface 10 on the opposite side, but the present invention is not limited thereto. And a negative electrode terminal 15 may be disposed. Further, the electrode group incorporated in the lithium ion secondary battery 1 is not particularly limited. For example, a strip-like positive electrode current collector sheet coated with a positive electrode mixture and a negative electrode mixture are applied. An electrode group in which a belt-like negative electrode current collector sheet is wound in a spiral around a plate-like shaft core via a belt-like separator sheet is preferably used.

  Next, the battery module will be described. FIG. 1 is a schematic perspective view showing an example of a battery module according to the present invention. FIG. 3 is an exploded perspective view showing an example of a schematic configuration of the battery module according to the present invention. As shown in FIGS. 1 and 3, the battery module 20 according to the present invention has a plurality (eight in the figure) of the lithium ion secondary battery 1 in which the flat portions 12 face each other in parallel with a gap. And the bottom surfaces 10 are arranged in the same direction. The plurality of lithium ion secondary batteries 1 are fixed by a positioning member (aligner) 6, a first frame 2, a second frame 3, and braces 4.

  The aligner 6 has a plurality of depressions that match the curved surface shape of the curved surface portion 13 of the lithium ion secondary battery 1 to be arranged, and both end portions (the curved surface portion 13 and the bottom surface 10 of the curved surface portion 13 of the lithium ion secondary battery 1). Between the lithium ion secondary battery 1 and the first frame 2 and between the lithium ion secondary battery 1 and the second frame 3. When the lithium ion secondary batteries 1 are arranged, both end portions of the curved surface portion 13 can be aligned with the aligner 6 so that the flat surface portion 12 faces in parallel with a gap. The material of the aligner 6 is not particularly limited, but is preferably made of resin from the viewpoint of weight reduction and processability.

  The first frame 2 and the second frame 3 are the framework of the battery module 20 and are connected to the brace 4 to give good torsional rigidity and vibration resistance to the entire battery module 20. From the viewpoint of the mechanical strength of the battery module 20, the first frame 2 and the second frame 3 are preferably made of an aluminum plate or a relatively thin steel plate. 1 and 3, the first frame 2 and the second frame 3 are arranged on the curved surface portion 13 side of the arranged lithium ion secondary batteries 1, but the present invention is not limited to this. Alternatively, it may be disposed on the bottom surface 10 side. Moreover, it is preferable that the brace 4 disposed on the curved surface portion 13 side is narrow so as not to inhibit the flow of the cooling air.

  The battery module 20 is preferably provided with a tab plate 5 that closes the bottom surface 10 side of the arranged lithium ion secondary batteries 1. By providing the end plate 5, the flow of cooling air can be controlled. In addition, a twill plate 5 ′ that closes the outside of the planar portion 12 of the lithium ion secondary battery 1 at the arranged end may be provided. The end plates 5, 5 'are preferably made of resin from the viewpoints of weight reduction and electrical insulation.

  In the battery module 20 shown in FIGS. 1 and 3, the positive terminal 14 and the negative terminal 15 of the arranged lithium ion secondary battery 1 are connected in series by the connecting terminal 7, and power is supplied from the module terminal 7 ′ to the outside or from the outside. Charged. However, the connection of the lithium ion secondary battery 1 in the present invention is not limited thereto, and the arranged lithium ion secondary batteries 1 may be connected in parallel, or a series connection and a parallel connection may be mixed. Also good.

There are no particular limitations on the procedure for assembling the battery module 20, and it is only necessary that a structure satisfying the provisions of the present invention can be achieved. For example, it can be assembled in the following procedure.
(1) The aligner 6 is placed inside the second frame 3, and the lithium ion secondary battery 1 is arranged in accordance with the recess of the aligner 6.
(2) The aligner 6 is placed on the arranged lithium ion secondary battery 1, and the positive terminal 14 and the negative terminal 15 of the adjacent lithium ion secondary battery 1 are connected by the connecting terminal 7.
(3) The module terminal 7 ′ is connected to the lithium ion secondary battery 1 at both ends.
(4) Place the end plates 5, 5 '.
(5) Cover the first frame 2 and connect and fix the first frame 2 and the second frame 3 with the brace 4.

  Next, the function and effect of the battery module according to the present invention will be described. FIG. 4 is a schematic perspective view showing the flow of cooling air in the battery module according to the present invention. FIG. 5 is a schematic front view of the flow of cooling air in the battery module according to the present invention as viewed from the bottom surface direction of the arranged lithium ion secondary batteries. FIG. 6 is a schematic side view of the flow of cooling air in the battery module according to the present invention as viewed from the plane portion direction of the arranged lithium ion secondary batteries. 4 to 6, for easy understanding, the arranged lithium ion secondary battery 1 and aligner 6 of the battery module 20 are mainly illustrated, and other components are omitted. .

  As shown in FIGS. 4 to 6, the aligners 6 are arranged at four positions on the end portions of the curved surface portions 13 of the arranged lithium ion secondary batteries 1. As indicated by the arrows in the figure, the cooling air flows from the cooling air inlet 8, passes through the gaps between the arranged lithium ion secondary batteries 1, and is discharged from the cooling air outlet 9 on the opposite side. At this time, since the curved surface portion 13 of the lithium ion secondary battery 1 is lined up at the cooling air inlet 8, the cooling air is not disturbed in its flow, and the lithium ions arranged along the shape of the curved surface portion 13 It is led to the gap between the secondary batteries 1 (see FIG. 5). Further, since the end plate 5 that closes the bottom surface 10 side of the arranged lithium ion secondary batteries 1 is provided, almost all of the inflowing cooling air is discharged from the cooling air outlet 9 (see FIG. 6). ).

  Here, the gap G between the arranged lithium ion secondary batteries 1 is preferably in a ratio of 1/15 to 1/3 with respect to the thickness T of the lithium ion secondary battery 1. If the gap G is smaller than (1/15) T, the flow of cooling air is disturbed, which is not preferable. On the other hand, if the gap G is larger than (1/3) T, the cooling efficiency is saturated for the increase in the volume of the battery module, which is not preferable.

  As described above, the battery module according to the present invention uses a plurality of lithium ion secondary batteries having a rounded rectangular prism shape, and faces each other so that a planar portion of each secondary battery has a gap. And the curved portions are arranged on the same side, the flow resistance in the vicinity of the cooling air inlet is small, and the cooling air can be easily guided to the gap between the secondary batteries. Moreover, since the end plate that closes the bottom surface side of the arranged lithium ion secondary batteries is provided, almost all of the inflowing cooling air is discharged from the cooling air outlet. As a result, there is no need to provide a cooling air guide outside the battery module, and it is possible to provide a battery module with improved cooling efficiency while minimizing an increase in the volume of the battery module.

1 ... Lithium ion secondary battery, 2 ... first frame, 3 ... second frame,
4 ... Bracing, 5, 5 '... Tsum, 6 ... Positioning member (aligner),
7 ... Connecting terminal, 7 '... Module terminal, 8 ... Cooling air inlet, 9 ... Cooling air outlet,
10 ... bottom surface, 11 ... side surface, 12 ... flat surface portion, 13 ... curved surface portion, 14 ... positive electrode terminal, 15 ... negative electrode terminal,
20 ... Battery module.

Claims (5)

A battery module combining a plurality of lithium ion secondary batteries,
Each of the lithium ion secondary batteries has a columnar shape including a pair of bottom surfaces and side surfaces, and the side surface has a shape of a rounded rectangular column including a pair of flat surface portions and a pair of curved surface portions,
A battery module, wherein the planar portions of the plurality of lithium ion secondary batteries face each other with a gap therebetween, and the bottom surfaces thereof face the same direction. The battery module according to claim 1,
The battery module, wherein a radius of curvature of the curved surface portion is a ratio of 1/2 to 2/3 with respect to a thickness of the lithium ion secondary battery. The battery module according to claim 1 or 2,
The battery module, wherein the gap has a ratio of 1/15 to 1/3 with respect to the thickness of the lithium ion secondary battery. The battery module according to any one of claims 1 to 3,
A battery module, further comprising a gable plate for closing a bottom surface side of the arranged lithium ion secondary batteries. The battery module according to any one of claims 1 to 4,
The plurality of lithium ion secondary batteries are fixed by a positioning member and a frame-shaped case,
The battery module, wherein the frame-like case has a brace.

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