Battery module

Abstract

To provide a battery module capable of reducing a weight as well as having an excellent cooling efficiency of a battery cell.SOLUTION: In a battery module 100A, a plurality of battery cells 1 is laminated to a lamination direction. Each battery cell 1 comprises a tub lead 30 to be expanded to a side direction of a cell outer casing body 20. A cooling jacket 60 in which a coolant is flown to an own internal space is provided to a side direction of a tub lead 30 along a lamination direction, a heat transmission member 50 connecting both of the tub lead 30 and the cooling jacket 60 is provided. The tub lead 30 is connected by a tub connection part 40J connecting both of the adjacent tub leads 30. The heat transmission member 50 is provided between a tub connection part 40J in the lamination direction and the opposing cooling jacket 60, and in a partition area surrounded by the tub connection part 40J, the cell outer casing body 20, and the tub lead 30 that is adjacent to the lamination direction, a gap part N where the heat transmission member 50 is not existed is provided.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a battery module in which a plurality of battery cells are stacked, and particularly to a technique for cooling this type of battery module.

Background Art

[0002] For example, in the technique described in Patent Document 1, a cooling flow path is linearly contacted with a bus bar of a battery cell in the stacking direction of the battery cells to cool the battery cells.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the battery cells in the technique described in the same document, since the cooling flow path is linearly contacted with the bus bar of the battery cell in the stacking direction, the heat conduction efficiency between the cooling flow path and the bus bar is poor, and there is room for improvement in improving the cooling efficiency of the battery cell. Therefore, the present invention has been made by paying attention to such problems, and an object thereof is to provide a battery module having excellent cooling efficiency of battery cells.

Means for Solving the Problems

[0005] In order to solve the above problems, a battery module according to one aspect of the present invention includes a battery element, a flat cell exterior body that houses the battery element, and a tab lead that protrudes from the battery element to the side of the cell exterior body. A plurality of battery cells each including these components are stacked in the stacking direction of the cell exterior bodies. The battery module includes a tab connection portion that electrically connects the tab leads adjacent to each other in the stacking direction, a cooling structure that is attached to the side of the tab connection portion along the stacking direction of the plurality of battery cells and through which a refrigerant flows in its internal space, and a heat transfer member that is provided to connect the tab connection portion and the cooling structure to each other and has electrical insulation. A void portion in which the heat transfer member does not exist is provided in a defined region surrounded by the tab connection portion, the cell exterior body, and the tab leads adjacent to each other in the stacking direction.

Effect of the Invention

[0006] According to the present invention, the cooling efficiency of the battery cell is excellent.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

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Figure 4

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Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0008] Hereinafter, embodiments of the present invention will be described with appropriate reference to the drawings. The all-solid-state battery in each embodiment is a secondary battery capable of multiple charge and discharge cycles. Note that the drawings are schematic. Therefore, it should be noted that the relationship between the thickness and the planar dimensions, the ratio, etc. are different from the actual ones, and there are parts where the dimensional relationships and ratios are different between the drawings. Also, the embodiments shown below exemplify devices and methods for embodying the technical idea of the present invention, and the technical idea of the present invention does not specify the materials, shapes, structures, arrangements, etc. of the constituent parts in the following embodiments.

[0009] [Battery Module] As shown in FIG. 1, the first embodiment is an all-solid-state battery including a battery module 100A formed by stacking a plurality of battery cells 1. The battery module 100A is housed in a battery case (not shown) and mounted on a vehicle. When mounting on the vehicle, a plurality of battery modules 100A are stored in a battery case (not shown) with the stacking direction of the battery cells 1 horizontal. In the battery case, in each battery module 100A, the plurality of stacked battery cells 1 are held in a pressurized state by an elastic restraint band or the like, and when the battery cells 1 expand and contract, the entire battery module 100A can follow the expansion and contraction along the stacking direction of the plurality of battery cells 1 in accordance with the expansion and contraction of the battery cells 1.

[0010] In the battery module 100A of the first embodiment, as shown in FIG. 2, the tab leads 31 and 32 of the positive and negative electrodes of each battery cell 1 are provided so as to project laterally from one side and the other side opposite thereto along the center line in the thickness direction of the battery cell 1.

[0011] Then, the tab leads 31 and 32 of the positive and negative electrodes are led out from the stacked electrode body in the cell exterior body 20 made of a laminate film and project laterally from the joint portion 23 of the cell exterior body 20. The tab leads 31 and 32 adjacent to each other in the stacking direction are electrically connected by a tab connection portion 40J at their tip portions, as shown in FIGS. 3(b) and (c). In this embodiment, the tab connection portion 40J is arranged to be located on the same plane along the stacking direction, and the tab leads 31 and 32 of a plurality of adjacent battery cells 1 in the stacking direction are connected by welding or the like.

[0012] In the battery module 100A of the present embodiment, the tab leads 31 and 32 of the positive and negative electrodes of the adjacent battery cells 1 are connected to each other by the tab connection portion 40J, so that the entire plurality of battery cells 1 are electrically connected in series. Each battery module 100A is provided with connection terminals at its upper and lower ends that are electrically connected to external devices (not shown). Hereinafter, in this specification, as shown in FIG. 2, when the tab leads 31 and 32 of the positive and negative electrodes are not particularly distinguished, the representative part number 30 is used, and it is simply described as the tab lead 30.

[0013] [Structure of Battery Cell] Next, the structure of the battery cell 1 will be described in detail with reference to FIG. 2. The battery cell 1 of the present embodiment is formed in a substantially rectangular shape in plan view. Note that the electrode structure of the battery cell 1 shown in the figure is a so-called non-bipolar type (internal parallel connection type), but it may also be a bipolar type (internal series connection type). Further, the shape of the battery cell 1 is not limited to a rectangular shape, and may be circular, elliptical, or the like.

[0014] As shown in the figure, the battery cell 1 of the present embodiment has a laminated electrode body 10 in which a positive electrode current collector 11, a positive electrode layer 13, a solid electrolyte layer 14, a negative electrode layer 15, and a negative electrode current collector 12 are laminated as a battery element. The laminated electrode body 10 is surrounded by a cell exterior body 20 made of a laminated film that sandwiches and encloses it from both sides in the thickness direction. The cell exterior body 20 has a metal foil layer and a resin layer. The cell exterior body 20 of the present embodiment is integrally formed with a metal foil layer sandwiched between the front and back resin layers.

[0015] The positive electrode current collector 11 and the negative electrode current collector 12 are formed in a rectangular thin plate shape by a metal material such as aluminum, nickel, iron, stainless steel, titanium, or copper, for example. The positive electrode current collector 11 and the negative electrode current collector 12 each have flexible lead electrodes 11p and 12p that extend laterally from one side forming the outer edge. At the tips of the lead electrodes 11p and 12p, the tab leads 31 and 32 of the positive and negative electrodes are respectively attached as rigid terminals.

[0016] The positive electrode layer 13 is disposed on both main surfaces of the positive electrode current collector 11 (only the main surface facing the negative electrode current collector 12 of the positive electrode current collector 11 at the end portions). The positive electrode layer 13 is composed of a positive electrode active material containing a substance that can release lithium ions during charging and occlude lithium ions during discharging by utilizing a redox reaction. Examples of the material of the positive electrode active material include lithium-transition metal composite oxides such as LiMn2O4, LiCoO2, LiNiO2, Li(Ni-Mn-Co)O2, and those in which a part of these transition metals is substituted with other elements, lithium-transition metal phosphate compounds, lithium-transition metal sulfate compounds, and the like.

[0017] The solid electrolyte layer 14 is a layer containing a solid electrolyte as a main component and interposed between the positive electrode layer 13 and the negative electrode layer 15. Examples of the solid electrolyte material include sulfide solid electrolytes and oxide solid electrolytes, but sulfide solid electrolytes are preferred. Examples of the sulfide solid electrolyte include materials of the LPS type (e.g., argyrodite (Li6PS5Cl)) and the LGPS type (e.g., Li10GeP2S12).

[0018] The negative electrode layer 15 is disposed on both main surfaces of the negative electrode current collector 12 (only the surface facing the positive electrode current collector 11 of the negative electrode current collector 12 at the end portions). The negative electrode layer 15 is composed of a negative electrode active material containing at least lithium metal or a substance that forms an alloy with lithium. That the negative electrode layer 15 contains lithium metal as a negative electrode active material means that in the case of disposing a lithium metal foil or lithium metal particles on the main surface of the negative electrode current collector 12, or in the case of depositing lithium metal on the main surface of the negative electrode current collector 12 using a positive electrode containing a positive electrode active material such as a lithium-transition metal composite oxide, a lithium-transition metal phosphate compound, or a lithium-transition metal sulfate compound. Further, that the negative electrode layer 15 contains a substance that forms an alloy with lithium means a substance containing at least one of In, Al, Si, and Sn.

[0019] [Cooling Structure of Battery Module] Next, the cooling structure of the battery module 100A of the first embodiment will be described. As shown in Fig. 3, the assembled battery module 100A of the first embodiment includes a cooling jacket 60 as a cooling structure for each of the tab leads 30 that project laterally to the left and right. Since the pair of left and right cooling structures 60 have the same configuration, they will be described below without particularly distinguishing between the left and right sides.

[0020] In the battery module 100A of the first embodiment, a pair of cooling jackets 60 through which a refrigerant flows in its internal space are attached to the left and right sides of the tab connection portion 40J. Each cooling jacket 60 is arranged along the stacking direction of the plurality of battery cells 1. A heat transfer member 50 made of a heat conductive resin having electrical insulation is provided between the left and right tab connection portions 40J and the cooling jackets 60.

[0021] In the battery module 100A of the first embodiment, the cooling jacket 60 is provided outside the heat transfer member 50. The cooling jacket 60 is a cooling source that cools the battery cell 20 via the heat transfer member 50. As shown in Fig. 1, the cooling jacket 60 of the first embodiment has a rectangular parallelepiped shape having substantially the same width as the heat transfer member 50, and the surface facing the heat transfer member 50 is in full contact with the heat transfer member 50 by resin molding. As the material of the cooling jacket 60, a metal such as copper or aluminum, or a composite material of metal and resin can be used.

[0022] The cooling structure 60 of the first embodiment has an internal space 60r through which the refrigerant R flows. As shown in Fig. 1, one end of the internal space 60r of the cooling jacket 60 that communicates is connected to the refrigerant R introduction flow path 61, and the other end is connected to the refrigerant R discharge flow path 62, and the refrigerant R is piped in the internal space of the cooling jacket 60 so as to be circulable.

[0023] The cooling jacket 60 of the present embodiment extends along a direction substantially parallel to the stacking direction of the battery cells 1 (the Z direction in Fig. 1). Therefore, since the internal space 60r of the cooling jacket 60 also extends along the stacking direction, the refrigerant R can also flow along the stacking direction. Note that, as the refrigerant R, any fluid that can cool the battery cell 1 may be used, and it may be a liquid or a gas. Further, the cooling jacket 60 may be connected to devices such as a pump and a radiator via a flow path.

[0024] As shown in FIG. 3, the cooling jacket 60 is fixed to the tab connection portion 40J via the heat transfer member 50 by filling the gap between the tab connection portion 40J and the cooling jacket 60 with resin molding by the heat transfer member 50 having electrical insulation. The heat transfer member 50 of the first embodiment covers the outer surfaces of the tab connections 40J that connect the positive and negative tab leads 31 and 32 protruding from both side surfaces of the battery cell 20 without any gaps. The width of the heat transfer member 50 in the present embodiment is smaller than the width of the battery cell 20 and is substantially the same as the width of the tab lead 30.

[0025] In the present embodiment, the heat transfer member 50 is in close contact with the surface facing the outside of the tab connection portion 40J (hereinafter also referred to as the "main surface"). In the present embodiment, the main surface of the tab connection portion 40J is in contact with the heat transfer member 50, but it is not limited thereto. In addition to the main surface of the tab connection portion 40J, a part of the tip side of the tab lead 30 connected to the tab connection portion 40J may be embedded in the heat transfer member 50. In the present embodiment, up to the portion of the outer peripheral surface of the bent portion on the tip side of the tab lead 30 is resin-molded and in contact with the heat transfer member 50. Note that the plurality of white arrows shown in FIG. 3(b) indicate an image of heat dissipation (the same applies to other figures hereinafter).

[0026] The heat transfer member 50 is made of a member having electrical insulation and a relatively high thermal conductivity. The thermal conductivity of the heat transfer member 50 may be, for example, 1 to 10 W / mK. The heat transfer member 50 can be created, for example, by molding a resin containing a filler or the like on the side surface of the battery cell 1. Examples of the filler include fibrous or particulate silicon or the like.

[0027] The heat transfer member 50 of the first embodiment is provided between the tab connection portion 40J and the cooling jacket 60 facing each other in the stacking direction so as to connect the tab connection portion 40J and the cooling jacket 60 to each other. Here, as shown in FIGS. 3(b) and 3(c), the battery module 100A of the first embodiment has a gap portion N where no heat transfer member 50 exists between the cell exterior body 20 and the tab lead 30.

[0028] In particular, in the battery module 100A of the present embodiment, in the region defined by surrounding the tab connection portion 40J, the cell exterior body 20, and the adjacent tab leads 30 in the stacking direction between the tab leads 30 of adjacent battery cells 1 in the stacking direction of the plurality of battery cells 1, the heat transfer member 50 is not filled at all. In other words, the heat transfer member 50 is provided only between the tab connection portion 40J and the cooling jacket 60 facing each other in the stacking direction, and the heat transfer member 50 is not intentionally arranged between the cell exterior body 20 and the tab lead 30. Thereby, while improving the heat conduction efficiency from the stacked electrode body 10 to the cooling structure on the tab lead 30 side, the weight of the entire battery module 100A is reduced.

[0029] It is preferable to cover the outside of the cooling jacket 60 with a heat insulating member. The heat insulating member is composed of a material having heat insulating properties. The material having heat insulating properties is not particularly limited, and examples thereof include a resin material having heat insulating properties. More specifically, examples of the resin material having heat insulating properties include foamed resins such as urethane foam. With such a heat insulating member, the heat transmitted from the tab leads 31 and 32 of the positive and negative electrodes can be concentrated on the cooling jacket 60 to improve the heat removal effect.

[0030] [Operational Effects] Next, the operational effects of the battery module 100A of the first embodiment will be described. The battery module 100A of the present embodiment has a cooling jacket 60 that fixes the tab leads 31 and 32 of the positive and negative electrodes so as to be coolable. Further, a gap between the tab connection portion 40J connecting the tab leads 31 and 32 of the positive and negative electrodes respectively and the cooling jacket 60 is filled by a heat transfer member 50 having electrical insulation properties. Therefore, the heat conduction efficiency between the tab leads 31 and 32 of the positive electrode and the negative electrode and the heat transfer member 50 can be improved. Furthermore, by directly contacting the cooling jacket 60 with the heat transfer member 50, the heat generated from the tab leads 31 and 32 of the positive electrode and the negative electrode can be efficiently exhausted through the heat transfer member 50 to the cooling jacket 60 and the refrigerant in the cooling jacket 60. Thus, the cooling efficiency (heat extraction effect) of the battery cell 1 can be improved.

[0031] In this embodiment, instead of directly cooling the main body portion (electrode stacking portion) of the battery cell 1, the tab leads 31 and 32 of the positive electrode and the negative electrode are cooled. According to the findings of the present inventors, since the tab leads 31 and 32 of the positive electrode and the negative electrode are more likely to become higher in temperature than the main body portion of the battery cell 1, in the battery module 100A according to the first embodiment, the risk due to the temperature rise of the tab leads 31 and 32 of the positive electrode and the negative electrode can be more effectively reduced.

[0032] In particular, in the battery module 100A of the first embodiment, as shown in FIG. 3, a heat transfer member 50 is provided so as to connect between the tab connection portion 40J connecting the tab leads 31 and 32 of the positive electrode and the negative electrode of the battery cell 1 and the cooling jacket 60, and a void portion N where the heat transfer member 50 does not exist is provided around the tab leads 31 and 32 between the cell exterior body 20 and the tab connection portion 40J, thereby improving the heat conduction efficiency between the tab leads 31 and 32 and the heat transfer member 50, improving the cooling efficiency of the battery cell 1, and reducing the weight of the battery module 100A [Invention 1].

[0033] The weight reduction effect due to the void portion N of the battery module 100A of the first embodiment will be described with reference to a comparative example. FIG. 10 shows a battery module 100 of the comparative example. The battery module 100 shown in FIG. 10 is different from the battery module 100A of the first embodiment in that the heat transfer member 50 is filled by resin molding even between the tab leads 30 facing each other in the stacking direction without providing a void portion N as in the first embodiment around the tab lead 30.

[0034] That is, in the battery module 100A of the first embodiment, as compared with the battery module 100 of the comparative example, the tab connection portion 40J is covered with the heat transfer member 50, and a void portion N is provided in the defined region surrounded by the tab connection portion 40J, the cell exterior body 20, and the tab leads 30 adjacent to each other in the stacking direction. As a result, the battery cell 1 can be effectively cooled and the battery module 100A can be lightened. That is, when the heat transfer member 50 is filled by resin molding even between the tab leads 30 as in the battery module 100 of the comparative example without providing the void portion N as in the first embodiment, according to the comparative test conducted by the present inventors, even if the heat conduction efficiency between the tab lead 30 and the heat transfer member 50 can be improved, the heat transfer member 50 between the adjacent tab leads 31 and 32 in the stacking direction has a lower contribution to cooling compared to the heat transfer member 50 that is in contact with the cooling jacket 60 or that molds the vicinity of the cooling jacket 60.

[0035] On the other hand, when mounted as a vehicle battery pack, increasing the volume and weight of the battery module directly leads to an increase in vehicle weight and material costs. Therefore, lightening the battery module is an important issue. In contrast, the present inventors provided a void portion N where no heat transfer member 50 exists in the defined region surrounded by the tab connection portion 40J, the cell exterior body 20, and the tab leads 30 adjacent to each other in the stacking direction, as in the battery module 100A of the first embodiment, and conducted a comparative test on the cooling efficiency and weight reduction compared to the battery module 100 of the comparative example. As a result, in the case of the battery module 100A of the first embodiment, compared with the battery module 100 of the comparative example, according to the battery module 100A of the first embodiment, since heat does not accumulate in the void portion N near the cell exterior body 20, the inventors have obtained the finding that while effectively cooling the battery cell 1, the battery module 100A can be lightened.

[0036] Here, in the battery module 100A of the first embodiment, since an all-solid-state battery configured to include at least lithium metal or a substance that forms an alloy with lithium as a negative electrode active material is adopted, the battery cell 1 expands and contracts in the stacking direction as lithium ions are intercalated and deintercalated by charging and discharging. Specifically, during discharge, since the thickness of the battery cell 1 becomes thinner, the distance between the battery cell 1 and the battery cell 1 contracts. Also, during charging, since the thickness of the battery cell 1 becomes thicker, the distance between the battery cell 1 and the battery cell 1 expands. On the other hand, in the battery module 100A of the first embodiment, as shown in FIG. 4, in the defined region surrounded by the tab connection portion 40J, the cell exterior body 20, and the adjacent tab leads 30 in the stacking direction of the plurality of battery cells 1, a void portion N where no heat transfer member 50 is filled at all is provided on the side of the cell exterior body 20. Therefore, it is suitable for the tab lead 30 to follow the deformation in the stacking direction as the battery cell 1 expands and contracts in the stacking direction. However, in the above first embodiment, an example in which the void portion N where no heat transfer member 50 is filled at all is provided in the defined region is shown. By providing the void portion N in at least a part of the defined region surrounded by the tab connection portion 40J, the cell exterior body 20, and the adjacent tab leads 30 in the stacking direction, the battery cell 1 can be effectively cooled and the effect of reducing the weight of the battery module 100A can be obtained.

[0037] Note that the battery module according to the present invention is not limited to the configuration shown in the above first embodiment, and various modifications are possible without departing from the gist of the present invention. For example, in the above first embodiment, a cooling jacket is exemplified as an example of the cooling structure 60, but it is not limited thereto, and various modes such as a pipe can be adopted as long as it is a cooling structure attached to the side of the tab connection portion 40J and having a refrigerant flowing through its internal space. Also, for the heat transfer member 50, various modes can be adopted as long as it is provided so as to connect the tab connection portion 40J and the cooling structure 60 to each other and has electrical insulation.

[0038] Hereinafter, specific examples of other embodiments (second to seventh embodiments) of the battery module according to the present invention will be described. In the following description of the second to seventh embodiments, the differences from the first embodiment and the resulting effects will be described, and the same reference numerals will be given to the configurations that are the same as or corresponding to those shown in the first embodiment, and the description thereof will be omitted as appropriate.

[0039] [Second Embodiment] FIG. 4 is a cross-sectional view showing an example of the configuration of the battery module 100B according to the second embodiment. Hereinafter, only the differences between the battery module 100B in the second embodiment and the first embodiment will be described, and the same reference numerals will be given to the configurations that are the same as or corresponding to those in the first embodiment, and the description thereof will be omitted (the same applies to other embodiments hereinafter). As shown in the figure, compared with the battery module 100A of the first embodiment, the battery module 100B of the second embodiment has an overhanging portion 64 where the cooling jacket 60, which is a cooling structure, projects between adjacent tab leads 30 in the stacking direction, and the heat transfer member 50 is also filled between the upper and lower tab leads 30 that face the upper and lower sides of the overhanging portion 64 in the stacking direction, which is different from the battery module 100A of the first embodiment. However, the other configurations are the same as those of the first embodiment.

[0040] Even in the battery module 100B according to the second embodiment, similar to the battery module 100A in the first embodiment, it is possible to improve the cooling efficiency and reduce the weight of the battery module 100B. Note that the overhanging range of the overhanging portion 64 is preferably a range where the heat transfer member 50 does not contact the cell exterior body 20. In particular, it is desirable to fix the range where the heat transfer member 50 is resin-molded on the tab connection portion 40J side rather than at the end of the joint portion 23 of the cell exterior body 20 in the projecting direction of the tab lead 30.

[0041] In particular, according to the battery module 100B according to the second embodiment, as shown in FIG. 4, the cooling jacket 60 has an overhanging portion 64 that protrudes between the tab leads 30 adjacent in the stacking direction, and the heat transfer member 50 is also filled between the overhanging portion 64 and the tab lead 30. Therefore, the flow rate can be reduced and turbulent flow can be generated due to the flow path resistance of the overhanging portion 64. Therefore, further improvement in cooling efficiency can be achieved [Invention 2].

[0042] Furthermore, in the case of the battery module 100B according to the second embodiment, the cooling jacket 60 has an overhanging portion 64 that protrudes between the tab leads 30 adjacent in the stacking direction, and the heat transfer member 50 is also interposed and filled between the overhanging portion 64 and the tab lead 30. Therefore, the tab connection portion 40J, and the tab leads 31 and 32 of the positive and negative electrodes are in three-dimensional contact with the heat transfer member 50 by a plurality of surfaces (three U-shaped surfaces). Therefore, it is suitable for improving the heat conductivity between the tab connection portion 40J, the tab leads 31 and 32 of the positive and negative electrodes, and the heat transfer member 50, and improving the cooling efficiency of the battery cell 1. Also, in the case of the battery module 100B according to the second embodiment, since the heat transfer member 50 in three-dimensional contact with a plurality of surfaces can improve the cooling efficiency, the cooling mechanism such as the cooling jacket 60 can be made smaller. Therefore, it is possible to obtain an energy-saving effect while achieving compactness. As a result, the volume energy density, weight energy density, required power amount, and required cost can be satisfied.

[0043] [Third Embodiment] FIG. 5 is a plan view showing an example of the configuration of the battery module 100C according to the third embodiment. Hereinafter, the differences between the battery module 100C in the third embodiment and the battery module 1A of the first embodiment will be described. As shown in the figure, in the battery module 100C of the third embodiment, the heat transfer member 50 is provided only in the portion facing the tab connection portion 40J, and is intermittently provided with a space between the tab connection portions 40J adjacent in the stacking direction, which is different from the battery module 100A of the first embodiment.

[0044] Even for the battery module 100C in the third embodiment, similar to the battery module 100A in the first embodiment, the cooling efficiency can be improved. In particular, according to the battery module 100C in the third embodiment, as shown in FIG. 5, since the heat transfer member 50 is intermittently provided with a space between adjacent tab connection portions 40J in the stacking direction, it is possible to further reduce the weight of the battery module 100A while effectively cooling the battery cell 1. Further, it is more suitable for the tab leads 31 and 32 to follow the deformation in the stacking direction in accordance with the expansion and contraction of the battery cell 1 in the stacking direction [Invention 3].

[0045] [Fourth Embodiment] FIG. 6 is a plan view showing an example of the configuration of the battery module 100D according to the fourth embodiment. Hereinafter, differences between the battery module 100D in the fourth embodiment and the battery module 1A in the first embodiment will be described. As shown in the figure, the battery module 100D in the fourth embodiment is different from the battery module 100C in the third embodiment in that the cooling structure has a rectangular tubular cooling pipe 60. Specifically, in the battery module 100D of the fourth embodiment, the cooling structure has a rectangular tubular cooling pipe 60. The entire cooling pipe 60 is arranged along the stacking direction facing the tab connection portion 40J that intersects the stacking direction, and has a meandering shape that bends at positions between adjacent tab connection portions 40J and 40J in the stacking direction.

[0046] Even for the battery module 100D in the fourth embodiment, similar to the battery module 100A in the first embodiment, the cooling efficiency can be improved. In particular, according to the battery module 100D in the fourth embodiment, as shown in FIG. 6, since the cooling structure arranges the rectangular tubular cooling pipe 60 in a meandering shape, in addition to the effects of the third embodiment, it is possible to further reduce the weight of the battery module 100D. Further, the flow velocity can be reduced and turbulent flow can be generated due to the flow path resistance caused by the meandering shape and the pipe shape, and further improvement in cooling efficiency can be achieved [Invention 4].

[0047] [Fifth Embodiment] FIG. 7 is a plan view showing an example of the configuration of the battery module 100E according to the fifth embodiment. Hereinafter, the differences between the battery module 100E in the fifth embodiment and the battery module 100D in the fourth embodiment will be described. As shown in FIG. 7, in the battery module 100 of the fifth embodiment, as shown in FIG. 7(d), with respect to the battery module 100D in the fourth embodiment, the rectangular cross-section of the cooling pipe 60 has an aspect ratio of "length in the direction parallel to the tab lead 30 (X direction) < length in the direction perpendicular to the tab lead 30 (Z direction)". That is, in the battery module 100 of the fifth embodiment, as shown in the figure, the cooling pipe 60 has a rectangular cross-section, and the surface including the long side of the rectangle is attached so as to face the tab connection portion 40J.

[0048] Even in the battery module 100E in the fifth embodiment, similar to the battery module 100A in the first embodiment, the cooling efficiency can be improved. In particular, according to the battery module 100E in the fifth embodiment, as shown in FIGS. 7(c) and 7(d), since the surface including the long side of the rectangle of the cooling pipe 60 is attached so as to face the tab connection portion 40J, the contact surface with the tab connection portion 40J can be made wider. Therefore, it is more suitable for further improving the cooling efficiency [Invention 5].

[0049] [Sixth Embodiment] FIG. 8 is a plan view showing an example of the configuration of the battery module 100F according to the sixth embodiment. Hereinafter, the differences between the battery module 100F in the sixth embodiment and the battery module 1A in the first embodiment will be described. As shown in FIG. 8, in the battery module 100F of the sixth embodiment, with respect to the battery module 100D in the fourth embodiment, the cooling pipe 60 is resin-molded between adjacent tab connection portions 40J in the stacking direction, between the tab leads 30 adjacent to each other in the stacking direction, so as to surround the periphery of the pipe by the heat transfer member 50, and has a folding structure that protrudes to the side of the tab connection portion 40J and is folded back in a U shape in the stacking direction in order.

[0050] Even in the battery module 100F in the sixth embodiment, similar to the battery module 100A in the first embodiment, the cooling efficiency can be improved. In particular, according to the battery module 100F in the sixth embodiment, as shown in FIG. 8, since the cooling pipe 60 has a folding structure that is folded back in order in the stacking direction at a position between the tab leads 30 adjacent to each other in the stacking direction, the tab leads 31 and 32 of the positive and negative electrodes are three-dimensionally in contact with the heat transfer member 50 by the upper and lower two surfaces in the stacking direction. Therefore, it is suitable for improving the cooling efficiency of the battery cell 1 by further improving the thermal conductivity between the tab leads 31 and 32 of the positive and negative electrodes and the heat transfer member 50. Also, in the case of the battery module 100F in the sixth embodiment, the heat transfer member 50 that is three-dimensionally in contact with the tab lead 30 on the upper and lower two surfaces sandwiches and surrounds the periphery of the cooling pipe 60 from above and below, so that the cooling efficiency can be further improved. Also, in the protruding direction of the tab lead 30, since the arrangement position of the cooling pipe 60 is inside the tab connection portion 40J, the cooling mechanism such as the cooling jacket 60 can be made smaller. Therefore, it is suitable for obtaining an energy-saving effect while making the battery module 100E more compact [Invention 6].

[0051] [Seventh Embodiment] FIG. 9 is a plan view showing an example of the configuration of the battery module 100G according to the seventh embodiment. Hereinafter, the differences between the battery module 100G in the seventh embodiment and the battery module 1A in the first embodiment will be described. In the battery module 100G according to the seventh embodiment, as shown in FIG. 9, the cooling pipe 60 has two systems of cooling pipes, namely the first cooling pipe 60A and the second cooling pipe 60B, which is different from the battery module 100A of the first embodiment. The first cooling pipe 60A has the same configuration as that in the fourth embodiment, and the second cooling pipe 60B has the same configuration as that in the sixth embodiment. In other words, the battery module 100G of the seventh embodiment has a configuration in which the cooling structure of the battery module 100D in the fourth embodiment and the cooling structure of the battery module 100E in the sixth embodiment are combined.

[0052] That is, as shown in FIG. 9, the first cooling pipe 60A uses a rectangular tubular cooling pipe, and the entire cooling pipe is arranged along the stacking direction facing the tab connection portion 40J that intersects the stacking direction, and has a meandering shape that bends at the positions between the adjacent tab connection portions 40J in the stacking direction. The second cooling pipe 60B is resin-molded by the heat transfer member 50 so as to surround the periphery of the pipe between the adjacent tab connection portions 40J in the stacking direction and between the adjacent tab leads 30 in the stacking direction, and has a folding structure that projects to the side of the tab connection portion 40J and is folded back in a U shape in the stacking direction in sequence.

[0053] Even in the battery module 100G according to the seventh embodiment, the cooling efficiency can be improved in the same manner as the battery module 100A in the above embodiment. In particular, in the battery module 100G according to the seventh embodiment, as shown in FIG. 9, the cooling pipe 60 has a first cooling pipe 60A located between the tab leads 30 facing the tab connection portion 40J, and a second cooling pipe 60B provided together with the first cooling pipe 60A and located between the adjacent tab leads 30 in the stacking direction. Therefore, by increasing the number of circuits of the cooling structure, the cooling efficiency can be further improved [Invention 7].

[0054] Furthermore, the battery module according to the present invention is not limited to the configurations shown in the first to seventh embodiments, and various modifications are possible without departing from the spirit of the present invention. For example, in the above embodiments, the example applied to the "all-solid-state battery" has been described, but the present invention is not limited thereto, and it can be applied to various battery modules in which a plurality of battery cells are stacked. However, if it is applied to the battery modules 100A to 100F in which the battery cell 1 expands and contracts in the stacking direction, like the "all-solid-state battery" shown in the first to seventh embodiments above, by providing the above-described void portion N, it is suitable for allowing the tab leads 31 and 32 to follow the deformation in the stacking direction according to the expansion and contraction.

[0055] Also, the battery cells 1 do not necessarily have to be electrically connected in series, and they may be electrically connected in parallel. Further, in the above embodiments, the tab leads 31 and 32 of the positive electrode and the negative electrode are directly connected to each other at the tab connection portion 40J, but the present invention is not limited thereto, and as the tab connection portion, they may be electrically connected via a bus bar. Also, various modifications are possible for the connection mode of the tab connection portion 40J. The tab leads 30 of adjacent battery cells 1, 1 can be connected to each other by welding or the like via a bus bar as the tab connection portion 40J.

[0056] FIG. 11 shows a modified example of the tab connection portion 40J. The example shown in FIG. 11(a) is a schematic diagram corresponding to the tab connection portion 40J shown in the above embodiments, and the tab leads 30 of the positive electrode and the negative electrode of each battery cell 1 adjacent vertically are folded back so that the tip portions overlap each other and are welded M. Also, in the example shown in FIG. 11(b), the tab leads 30 of the positive electrode and the negative electrode of each battery cell 1 adjacent vertically are arranged so as to project laterally, and are connected to each other by welding M via a U-shaped (U-shaped) bus bar 40. Further, in the example shown in FIG. 11(c), the tab leads 30 of the positive electrode and the negative electrode of each battery cell 1 adjacent vertically are folded back to the same side along the stacking direction at the tip portions and are connected to each other by welding M via a flat bus bar 40.

Explanation of Reference Numerals

[0057] 1…Battery cell 10…Stacked electrode body (battery element) 11…Positive current collector 11p…Lead-out electrode 12…Negative current collector 12p…Lead-out electrode 13…Positive electrode layer 14…Solid electrolyte layer 15…Negative electrode layer 20…Cell exterior body 23…Joint part 30…Tab lead 31…Positive tab lead 32…Negative tab lead 40J…Tab connection part 50…Heat transfer member 60…Cooling structure (cooling pipe (cooling flow path), cooling jacket) 60r…Internal space 61…Inlet flow path 62…Outlet flow path 64…Overhanging part 65…Parallel part 66…Bending part 100A~100F…Battery module (all-solid-state battery) R…Refrigerant N…Void part

Claims

1. A battery module in which a plurality of battery cells, each comprising a battery element, a flat cell exterior housing that houses the battery element, and a tab lead that protrudes laterally from the battery element to the side of the cell exterior housing, are stacked in the stacking direction of the cell exterior housings, a tab connection portion that electrically connects the tab leads adjacent to each other in the stacking direction, a cooling structure that is attached to the side of the tab connection portion along the stacking direction of the plurality of battery cells and through which a refrigerant flows in its internal space, a heat transfer member that is provided to connect the tab connection portion and the cooling structure to each other and has electrical insulation, is provided, and the battery module is characterized in that a void portion in which the heat transfer member does not exist is provided in a defined region surrounded by the tab connection portion, the cell exterior housing, and the tab leads adjacent to each other in the stacking direction.

2. The cooling structure has a cooling overhang portion that protrudes between the tab leads adjacent to each other in the stacking direction, and the heat transfer member is interposed between the cooling overhang portion and the tab lead. The battery module according to claim 1.

3. The heat transfer member is intermittently provided in the stacking direction with a space between the tab connection portions adjacent to each other in the stacking direction. The battery module according to claim 1.

4. The cooling structure has a tubular cooling pipe. The battery module according to claim 3.

5. The cooling pipe has a rectangular cross section, and a surface including the long side of the rectangle is attached so as to face the tab connection portion. The battery module according to claim 4.

6. The cooling pipe is piped at a position between the tab leads adjacent to each other in the stacking direction, and has a folding structure that protrudes to the side of the tab connection portion and is folded back in a U shape in the stacking direction in order. The battery module according to claim 4.

7. The cooling pipe is a first cooling pipe disposed at a position facing the tab connection portion, and a second cooling pipe provided in parallel with the first cooling pipe and piped at a position between the tab leads adjacent to each other in the stacking direction, and has. The battery module according to claim 4.

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