JP5060809B2 - Battery module - Google Patents

Description

  The present invention relates to a battery module, and in particular, a plurality of single cells in which the battery lid and the battery can have different polarities are arranged in a row so that the bottom surfaces of the battery lid and the battery can alternate in the lateral direction. The present invention relates to a battery module in which a plurality of sub-modules fixed and electrically connected with a frame are housed, arranged and electrically connected in an outer case.

  Conventionally, for example, a nickel-hydrogen secondary battery, a lithium-ion battery, and the like are used for a large current charging / discharging power source of an electric vehicle such as a hybrid electric vehicle (HEV) driven by an engine and a motor or a genuine electric vehicle (PEV) driven only by a motor. A battery module in which a plurality of cells such as secondary batteries are connected in series or in parallel is used.

  As an example of such a battery module, a plurality of long cylindrical (flat) cells having a long axis and a short axis are used, and these single cells are long in a plane parallel to an oval cross section. A technique for disposing the shaft at an inclination is disclosed (for example, see Patent Document 1).

JP 2001-035461 A

  For example, a battery module for EV or HEV often discharges a large current because the motor to be driven has a high output, but a battery module that does not consider cooling performance dissipates the Joule heat generated by the large current discharge. There was a problem that the battery temperature would rise without being able to. On the other hand, when the battery module outer case is manufactured so as to have a large opening area in order to improve the cooling performance, problems such as deformation of the outer case due to insufficient strength arise.

  An object of the present invention is to provide a high-strength battery module that can suppress an increase in temperature even when a large current is charged and discharged.

In order to solve the above-mentioned problems, the present invention provides a plurality of unit cells in which a battery lid and a battery can have different polarities, and the unit cells are arranged such that the bottom surfaces of the battery lid and the battery can alternate in a side surface direction. A plurality of sub-modules arranged in a row and fixed by a frame and electrically connected, and a plurality of sub-modules housed in, arranged in, and electrically connected to, at least one surface of the outer case A polygonal structure is provided, and an insulating plate having a ventilation hole is provided on a battery-side surface of the polygonal structure or on both surfaces of the polygonal structure .

In the present invention, since the polygonal structure is arranged on at least one surface of the outer case, the cooling cell is blown from the polygonal mesh-like cavity of the polygonal structure, thereby cooling the unit cell that has generated heat due to the large current charge / discharge. In addition, since the polygonal structure has high strength against the load, it has excellent durability, and a high-strength battery module can be obtained while improving the cooling performance . Insulation plates with vents are formed on both the battery-side surface and the polygonal structure, ensuring insulation between the cells and the polygonal structure, Since the impact is supported by the surface rather than partially by the polygonal structure, the load of the submodule or the impact at the time of collision can be more evenly distributed to the polygonal structure. you increase load As such a polygonal structure, for example, a honeycomb structure can be used, and as a material, for example, aluminum or an aluminum alloy can be used.

In the present invention, the polygonal structure and the insulating plate may be integrated. Such an aspect and other effects of the present invention will be described in detail in the section of the embodiment of the invention described later.

According to the present invention, since the polygonal structure is arranged on at least one surface of the exterior case, the unit cell that generates heat by charging / discharging the large current by blowing cooling air from the polygonal mesh cavity of the polygonal structure. it is possible to cool the order of the polygon structure high strength against a load, is excellent in durability, while improving the cooling performance, the battery module of high strength can be obtained and, polygonal structure Insulation plates with ventilation holes are formed on the battery side of the body or on both sides of the polygonal structure, ensuring insulation between the cells and the polygonal structure, and the load or collision of the submodule. Since a part of the polygonal structure is not partially supported by the polygonal structure, the load of the submodule or the impact at the time of collision can be more evenly distributed to the polygonal structure. Can withstand load increase That, effect it is possible to obtain that.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an exemplary embodiment in which the present invention is applied to a battery module (hereinafter abbreviated as a module) containing a large number of single cells will be described with reference to the drawings. In addition, the battery module of this embodiment is used as a power source for HEV or the like by itself or by connecting a plurality of battery modules in series or series-parallel.

(Overview)
As shown in FIGS. 8 and 9, the battery module 60 of the present embodiment (hereinafter abbreviated as “module 60”) includes a plurality of submodules 40 housed and disposed in an outer case. As shown in FIG. 4 and FIG. 5, the submodule 40 is obtained by housing the assembled battery 30 in a frame configured by the assembled battery holder 36 and the assembled battery covers 34 and 35. As shown in FIGS. 2 and 3, the assembled battery 30 is configured as an assembly (an assembled battery) in which four flat unit cells 20 are connected in series. Hereinafter, the configuration of the module 60 including the assembly procedure will be described in the order of the assembly (unit) of the assembled battery 30, the sub module 40, and the module 60 from the unit cell 20 of the minimum unit.

(Single cell 20)
<Positive electrode plate>
Lithium manganese complex oxide powder as a positive electrode active material, scaly graphite as a conductive material, and polyvinylidene fluoride (PVDF) as a binder were mixed at a weight ratio of 85: 10: 5, and this was mixed with N- A slurry in which methylpyrrolidone (NMP) was added and kneaded was applied to both surfaces of an aluminum foil having a thickness of 20 μm. Then, the positive electrode of width 80mm and thickness 170micrometer was obtained by drying, pressing, and cutting. Note that one side in the longitudinal direction of the aluminum foil was cut out in a rectangular shape, and the remainder of the cutout was used as a positive electrode lead piece.

<Negative electrode plate>
10 parts by mass of polyvinylidene fluoride as a binder is added to 90 parts by mass of the amorphous carbon powder as the negative electrode active material, and NMP as a dispersion solvent is added and kneaded to the slurry. It apply | coated to both surfaces of 10 micrometers rolled copper foil. Thereafter, drying, pressing, and cutting were performed to obtain a negative electrode having a width of 85 mm and a thickness of 130 μm. Note that one side in the longitudinal direction of the rolled copper foil was cut out in a rectangular shape, and the remainder of the cutout was used as a negative electrode lead piece.

<Preparation of the unit cell 20>
As shown in FIG. 1, the produced positive and negative electrodes were wound together with a polyethylene separator having a width of 90 mm and a thickness of 40 μm so that these bipolar plates were not in direct contact with each other, thereby producing a wound group 6. At the center of winding, a hollow flat shaft core 1 made of polypropylene was used. At this time, the positive electrode lead piece 2 and the negative electrode lead piece 3 were respectively positioned on opposite end surfaces of the wound group 6.

  The positive electrode lead piece 2 is deformed, and all of the positive electrode lead piece 2 is gathered and brought into contact with the vicinity of the buttocks circumferential surface integrally projecting from the periphery of the positive electrode current collecting ring 4, and then the positive electrode lead piece 2 and the buttocks circumferential surface are ultrasonically welded Then, the positive electrode lead piece 2 was connected to the collar surface. On the other hand, the connection operation between the negative electrode current collection ring 5 and the negative electrode lead piece 3 was performed in the same manner as the connection operation between the positive electrode current collection ring 4 and the positive electrode lead piece 2. Thereafter, an insulating coating was applied to the entire circumference of the collar surface of the positive electrode current collecting ring 4, and the wound group 6 was inserted into a nickel-plated steel battery can 7.

  A negative electrode lead plate 8 for electrical conduction is welded to the negative electrode current collecting ring 5 in advance. After inserting the wound group 6 into the battery can 7, the bottom of the battery can 7 and the negative electrode lead plate 8 are welded. did. A stepped portion in which the battery can wall is bent and protruded inward is formed in the battery can opening.

  On the other hand, the positive electrode current collector ring 4 is preliminarily welded with a positive electrode lead 9 composed of a plurality of aluminum ribbons, and the other end of the positive electrode lead 9 is sealed with a battery for sealing the battery can 7. Welded to the lower surface of the lid 10. The battery lid 10 includes a lid case 12, a lid cap 13, and a stainless steel gas discharge valve 11 welded to the lid case 12, and these are laminated to crimp the periphery of the lid case 12. It is assembled by.

  A predetermined amount of non-aqueous electrolyte that can infiltrate the entire wound group 6 is injected into the battery can 7, and then the battery can 7 is covered with the battery cover 10 so that the positive electrode lead 9 is folded, and made of EPDM resin. A flat lithium ion secondary battery (unit cell) 20 having a length of 108 mm, a width of 34 mm, a height of 117 mm, and a capacity of 10.0 Ah was completed by crimping with a gasket.

In the non-aqueous electrolyte, lithium hexafluorophosphate (LiPF ₆ ) is dissolved at a concentration of 1 mol / liter in a mixed solution in which ethylene carbonate and dimethyl carbonate are mixed at a volume ratio of 1: 2. Was used.

<Production of assembled battery 30>
As shown in FIGS. 2 and 3, using the four unit cells 20, the upper surface of the unit cell on which the gas discharge valve 11 is arranged faces the side surface of the assembled battery 30, and the upper surface and the bottom surface are alternated. Arranged in a row. Thereafter, the bus bars A31 and B32 were arranged to electrically connect adjacent unit cells in series, and each bus bar and the unit cells 20 were temporarily connected. In addition, the battery pack 30 was prepared by arranging the bus bar C33 and temporarily connecting the battery packs to the battery cells.

<Preparation of submodule 40>
As shown in FIGS. 4 and 5, the submodule 40 was supported (fixed) by the assembled battery holder 36 that covers the assembled battery 30 from both sides as well as the assembled battery cover A34 and the assembled battery cover B35 that cover the assembled battery 30 from both sides. The assembled battery cover A34 and the assembled battery cover B35 are provided with a gas exhaust valve hole 37 and a welding hole 38. The gas exhaust valve hole 37 is in an abnormal state such as when the unit cell 20 is overcharged or collapsed. In order to make it easier to discharge the gas generated and ejected inside the unit cell to the outside of the submodule 40. The welding hole 38 is provided for resistance welding of each of the bus bar A31, bus bar B32, bus bar C33 and the unit cell 20, and the welding electrode for resistance welding is applied to the bus bar through the hole 38 for welding. The unit cell 20 and each bus bar were in contact with each other and subjected to main welding by resistance welding, so that the submodule 40 was produced.

<Production of module 60>
As shown in FIGS. 6 and 7, the insulating plate 41 having a plurality of rectangular ventilation holes and the frame body 42 are integrated, and a length of 1000 mm and a width made of an aluminum alloy foil having a thickness of 20 μm are integrated therein. A honeycomb structure 43 having a height of 100 mm and a height of 10 mm is disposed, and an insulating plate 44 in which a plurality of rectangular ventilation holes are similarly formed is disposed on the upper surface of the honeycomb structure 43 on the battery side. The body 42, the honeycomb structure 43, and the insulating plate 44 were integrated to produce a lower case 45.

  After that, as shown in FIGS. 8 and 9, the submodules 40 are arranged in the lower case 45 so as to be symmetrical in two rows by seven. A separator 46 is provided between the back surfaces of the submodules 40 arranged symmetrically in two rows to prevent a short circuit due to electrical contact on the back surface of the submodule. Further, the upper case 47 is disposed on the upper surface of the submodule 40. In order to electrically connect adjacent submodules 40, each bus bar C33 of each adjacent submodule 40 was screwed. In order to electrically connect the sub-modules 40 arranged in two rows, the bus bar D48 was arranged and screwed to the bus bar C33 of the sub-module 40 on the side where the bus bar D48 was arranged. Thereby, 14 submodules 40 were electrically connected in series. The horizontal case A49, the horizontal case B50, and the horizontal case C51 were screwed to the lower case 45 and the upper case 47, respectively, to complete the manufacture of the module 60. In the module 60 of this embodiment, 56 unit cells 20 are connected in series.

  Next, effects and the like of the module 60 of the present embodiment will be described.

  The module 60 of the present embodiment includes four unit cells 20 in which the battery lid 10 and the battery can 7 have different polarities, and the unit cells 20 are arranged so that the bottom surfaces of the battery lid 10 and the battery can 7 are alternated in the side surface direction. The assembled battery 30 is arranged in a line, and the assembled battery 30 is fixed by a frame body including the assembled battery holder 36 and the assembled battery covers 34 and 35 and electrically connected to form the submodule 40. It is configured by housing, arranging and electrically connecting in a hexahedron outer case made up of 14 pieces, a lower case 45, an upper case 47, and lateral cases 49, 50, 51. A honeycomb structure 43 is disposed in the lower case 45 constituting the. According to the module 60, since the honeycomb structure 43 is arranged in the lower case 45, the unit cell 20 that has generated heat due to large current charging / discharging is cooled by blowing cooling air from the hexagonal mesh-shaped cavity of the honeycomb structure 43. can do. In addition, since the honeycomb structure 43 has high strength with respect to the load, it is superior in durability to an exterior case made of a resin alone, and a high-strength battery module can be obtained while improving cooling performance. .

  In addition, the module 60 includes an insulating plate 44 on the surface of the honeycomb structure 43 on the battery side, and a ventilation hole is formed in the insulating plate 44, thereby ensuring insulation between the unit cell 20 and the honeycomb structure 43. At the same time, the load of the submodule 40 or the impact at the time of collision is not partially supported by a part of the honeycomb structure 43 but is supported by the surface, so the load of the submodule 40 or the impact at the time of collision is applied to the honeycomb structure 43. On the other hand, since the load can be more evenly distributed, the load resistance increases.

  Further, the module 60 includes the insulating plates 41 and 44 on both surfaces of the honeycomb structure 43, thereby ensuring insulation not only on the battery side but also on the surface opposite to the battery side, and on the side opposite to the battery side of the honeycomb structure 43. Because a part of the honeycomb structure 43 is not partially supported by the load or impact of the surface, but is supported by the surface, the load of the submodule or impact at the time of collision is more evenly applied to the honeycomb structure. Can be dispersed.

  Further, the module 60 is improved in workability in the assembly process because the honeycomb structure 43 and the insulating plates 41 and 44 are integrated.

  Furthermore, in the module 60, since the honeycomb structure 43 is made of aluminum or aluminum alloy, aluminum has a low density among metals, is a general-purpose product, and a foil product can be easily manufactured. For this reason, a thin-film honeycomb structure can be easily manufactured, and a high-strength battery module can be manufactured by taking advantage of the characteristics of a metal with light weight and low cost.

  On the other hand, the unit cell 20 constituting the assembled battery 30 is led out from the lower end surface portion of the wound group 6 and connected to the inner bottom surface of the battery can 7, and is led out from the upper end surface portion of the wound group 6 to the bottom surface of the battery lid 10. Is connected to. Therefore, the lengths of the negative electrode conductive member (negative electrode lead piece 3, negative electrode current collecting ring 5, negative electrode lead plate 8) and positive electrode conductive member (positive electrode lead piece 2, positive electrode current collecting ring 4, positive electrode lead 9) can be shortened. The internal resistance of the unit cell 20 can be kept small. Moreover, since the battery pack 10 of the four flat cell 20 and the bottom face of the battery can 7 are alternately arranged in a line, the assembled battery 30 can shorten the length of the bus bars A31 and B32. In addition, the inter-cell connection resistance when the assembled battery 30 is configured can be reduced. Therefore, since the assembled battery 30 has a small resistance as a whole, it has excellent input / output characteristics, can be charged / discharged with a large current, and can be suitably used as a power source for HEVs. Further, in the assembled battery 30, the gas discharge valve 11 is arranged on the battery cover 10 of the unit cell 20, the battery cover 10 of the unit cell 20 faces the side surface of the assembled battery 30, and the battery cover 10 of the unit cell 20. The bottom surfaces of the battery cans 7 are alternately arranged in a line. For this reason, the gas generated inside the battery at the time of battery abnormality can be quickly discharged without causing problems such as closing the gas discharge valve 11. Therefore, it is possible to obtain a module 60 having a high volume density and excellent input / output characteristics while ensuring safety.

  Furthermore, in the assembled battery 30, the battery can 7 and the battery lid 10 of the unit cell 20 have different polarities, the upper surface of the unit cell 20 faces the side surface of the assembled battery 30, and the upper surface and the bottom surface of the unit cell 20 alternate. The number of unit cells 20 is four (even number). Therefore, the bus bar C33 connected to the positive electrode terminal of the unit cell 20 on the highest potential side of the battery pack 30 and the bus bar C33 connected to the negative electrode terminal of the unit cell 20 on the lowest potential side are on the same side of the battery pack 30. When the plurality of assembled batteries 30 are arranged, the bus bars C33 of the assembled batteries 30 can be aligned on one side surface, which facilitates the connection between the assembled batteries 30 and reduces the space for connection. it can.

  The submodule 40 includes a frame body including an assembled battery holder 36 and assembled battery covers 34 and 35 that cover the assembled battery 30, and the unit cell 20 is firmly fixed by the frame body. Further, since the single cells 20 are welded by the bus bars 31 and 32, even if the module 60 is mounted on the vehicle and affected by vibration, the single cells 20 do not move.

  Furthermore, the assembled battery covers 34 and 35 of the submodule 40 are formed with a gas discharge hole 37 of the gas discharge valve 11 and a welding round hole 38 for connecting the unit cell 20. Since the gas discharge hole 38 of the gas discharge valve 11 is formed, the assembled battery 20 can be supported by the frame and welded in a state where the position of the single battery 20 and each bus bar is fixed. The reproducibility of the welding position between the battery 20 and the bus bar is high, and productivity can be improved without causing poor welding.

  In the module 60, 14 submodules 40 are symmetrically arranged in two rows and accommodated in an outer case, and the submodules 40 are electrically connected. For this reason, it is possible to increase the volume density without creating a wasteful space in the module 60 such as opening a space for one submodule.

  Further, in the module 60, the outer case is composed of an upper case 47, a lower case 45, and substantially flat horizontal cases 49, 50, 51, and each case is separable. Since some cases can be attached after the connection, workability can be improved.

  In the present embodiment, the honeycomb structure 43 is exemplified as the polygonal structure. However, the present invention is not limited to this, and a polygonal structure such as a triangle, a quadrangle, a pentagon, a heptagon, an octagon, or the like is used. You may make it use. In the present embodiment, the lower case 45 provided with the insulating plates 41 and 44 on both surfaces of the honeycomb structure 43 is illustrated. However, in order to reduce weight and size, the honeycomb structure 43 is provided on the battery side surface. Only the insulating plate 44 may be provided.

  Moreover, in this embodiment, although the lithium ion secondary battery was illustrated as the single battery 20, this invention is not limited to this, For example, it is applicable to other secondary batteries, such as a nickel-hydrogen secondary battery. Needless to say. Further, in the present embodiment, the HEV power supply module 60 is illustrated, but the present invention is not limited to this, and can be applied to other uses such as a stationary power supply.

  Since the present invention provides a high-strength battery module that can suppress an increase in temperature even when charged and discharged with a large current and contributes to the manufacture and sale of battery modules, it has industrial applicability. .

It is sectional drawing of the cell which comprises the battery module of embodiment which can apply this invention. It is a front external appearance perspective view of the assembled battery which assembled the cell. It is a back side external appearance perspective view of an assembled battery. It is an external appearance perspective view which shows the assembly state of the submodule which fixed the cell which comprises an assembled battery with the frame, and was electrically connected in series. It is an external appearance perspective view of a submodule. It is an external appearance perspective view which shows the assembly state of the lower case of a battery module. It is an external appearance perspective view of a lower case. It is an external appearance perspective view which shows the assembly state of a battery module. It is an external appearance perspective view of a battery module.

Explanation of symbols

7 Battery can 10 Battery lid 20 Cell 34, 35 Battery cover (part of the frame)
36 Battery pack holder (part of the frame)
40 Submodule 41 Insulating plate 43 Honeycomb structure (polygonal structure)
44 Insulating plate 45 Lower case (part of exterior case)
47 Upper case (part of outer case)
49, 50, 51 Horizontal case (part of exterior case)

Claims (4)

A plurality of single cells having different polarities between the battery lid and the battery can are arranged in a row so that the bottom surfaces of the battery lid and the battery can alternate in the side surface direction, and are fixed by a frame. A battery module in which a plurality of connected sub-modules are housed, arranged and electrically connected in an outer case, wherein a polygonal structure is arranged on at least one surface of the outer case , and the polygonal structure A battery module comprising an insulating plate having ventilation holes formed on a battery side surface of the body or on both surfaces of the polygonal structure .   The battery module according to claim 1, wherein the polygonal structure is a honeycomb structure. The battery module according to claim 1 , wherein the polygonal structure and the insulating plate are integrated. The battery module according to any one of claims 1 to 3 , wherein the polygonal structure is made of aluminum or an aluminum alloy.

Images