Battery module

Abstract

To provide a battery module capable of sufficiently securing heat dissipation from the inside to the outside of a battery cell.SOLUTION: A battery module 11 includes: a plurality of battery cells 20 each including a metal layer and a heat seal layer, the plurality of battery cells having a laminate film 22 in which an electrode body is accommodated and a heat seal layer in a peripheral edge portion 24 is joined; a case 30 in which the battery cells 20 are accommodated in a state of being laminated in a thickness direction; and a heat conductive member 16 provided on an inner wall 36 of the case 30 so as to be in contact with the metal layer exposed from the peripheral edge portion 24 and configured to dissipate heat from the battery cells 20.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a battery module. [Background technology]

[0002] Battery modules in which battery cells are constructed in a structure that promotes heat dissipation by thermal conduction through at least a portion of the sealed portion of a battery case where no electrode terminals are located have been known for some time (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2011-504286 Summary of the Invention [Problem to be solved by the invention]

[0004] However, if the thermally conductive member is a dedicated member separate from the members that make up the battery cell, the thermal conduction path when dissipating heat inside the battery cell to the outside may become discontinuous inside the battery cell, which may result in insufficient heat dissipation from the inside of the battery cell to the outside.

[0005] SUMMARY OF THE PRESENT DISCLOSURE In view of the above, an object of the present invention is to provide a battery module that can ensure sufficient heat dissipation from the inside to the outside of the battery cells. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, a battery module of a first aspect of the present invention comprises a plurality of battery cells comprising a metal layer and a heat seal layer, housing an electrode body and having a laminate film to which the heat seal layer is joined at its peripheral portion, a case in which the battery cells are housed in a stacked state in the thickness direction, and a thermally conductive material provided on an inner wall of the case so as to be in contact with the metal layer exposed from the peripheral portion and which dissipates heat from the battery cells.

[0007] According to the first aspect of the invention, the battery cells have a laminate film including a metal layer and a heat seal layer. The laminate film houses an electrode body, and the heat seal layer is joined at the periphery of the laminate film. The battery cells are housed in a case in a stacked state in the thickness direction, and a thermally conductive material that contacts the metal layer exposed from each periphery is provided on the inner wall of the case. This allows heat from the battery cells to be dissipated. In other words, the thermally conductive material that directly contacts the metal layer of the laminate film ensures sufficient heat dissipation from the inside to the outside of the battery cells.

[0008] A second aspect of the battery module according to the present invention is a battery module according to the first aspect, wherein the inner wall of the case is formed with a plurality of recesses capable of accommodating the peripheral portion and the thermally conductive material, and the metal layer exposed from the peripheral portion is in contact with the thermally conductive material inside the recesses.

[0009] According to the second aspect of the invention, the inner wall of the case is formed with a peripheral portion and a plurality of recesses capable of accommodating a thermally conductive material. The metal layer exposed from the peripheral portion is in contact with the thermally conductive material inside each recess. Therefore, each battery cell is fixed and the position of each battery cell is stabilized.

[0010] A battery module according to a third aspect of the present invention is the battery module according to the second aspect, wherein each of the recesses houses the peripheral portions of two adjacent battery cells.

[0011] According to the third aspect of the invention, the peripheral edges of two adjacent battery cells are housed in each recess, which improves the volumetric efficiency of each battery cell relative to the case compared to a configuration in which each recess houses one peripheral edge of each battery cell.

[0012] A fourth aspect of the battery module according to the present invention is a battery module according to the second or third aspect, wherein the tip surfaces of the peripheral portions housed within the recess are configured to be positioned on the same plane.

[0013] According to the fourth aspect of the invention, the end faces of the peripheries housed inside the recesses are located on the same plane. That is, the lengths of the peripheries housed inside the recesses of the battery cells are uniform. This improves the volumetric efficiency of the battery cells relative to the case, and further stabilizes the posture of the battery cells.

[0014] A fifth aspect of the battery module according to the present invention is a battery module according to any one of the first to fourth aspects, wherein the battery cells housed in the case are formed such that the thickness of the metal layer is thicker at the center in the stacking direction than at both end sides in the stacking direction.

[0015] According to the fifth aspect of the invention, the thickness of the metal layer of each battery cell housed in the case is thicker at the center of the stacking direction of each battery cell than at both ends of the stacking direction. It is known that in a stack of multiple battery cells, the temperature tends to rise more easily toward the center of the stacking direction, and that the thicker the metal layer, the higher its thermal conductivity. Therefore, heat dissipation from the inside to the outside of each battery cell is efficiently ensured in the stacking direction. Effect of the Invention

[0016] As described above, according to the present invention, it is possible to ensure sufficient heat dissipation from the inside to the outside of the battery cell. [Brief description of the drawings]

[0017] [Figure 1]1 is a schematic plan view showing an electric vehicle equipped with a battery module according to an embodiment of the present invention. [Diagram 2] 1 is a schematic perspective view showing a configuration of a battery module according to an embodiment of the present invention. [Diagram 3] 1 is a schematic plan view showing the configuration of a battery module according to an embodiment of the present invention with a top cover removed. [Figure 4] 2 is a schematic front view showing the configuration of a battery cell accommodated in the battery module according to the embodiment, as viewed in the thickness direction. FIG. [Diagram 5] 1A is a schematic cross-sectional view showing the internal structure of a battery module according to the first embodiment, as viewed from the vehicle width direction; and FIG. 1B is a schematic cross-sectional view showing the internal structure of a battery module according to a modified example of the first embodiment, as viewed from the vehicle width direction. [Figure 6] 11 is a schematic cross-sectional view showing the internal structure of a battery module according to a second embodiment, as viewed in the vehicle width direction. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. For the sake of convenience, the arrow UP shown in each drawing indicates the vehicle upward direction, the arrow FR indicates the vehicle forward direction, and the arrow LH indicates the vehicle leftward direction. Therefore, in the following description, when the directions of up / down, front / rear, and left / right are described without special mention, they refer to up / down in the vehicle up / down direction, front / rear in the vehicle front / rear direction, and left / right in the vehicle left / right direction (vehicle width direction). In addition, the left / right direction is synonymous with the vehicle width direction.

[0019] In addition, the size of the components in each figure is conceptual, and the relative relationship between the sizes of the components is not limited to this. In addition, in this embodiment, a numerical range indicated using "~" means a range including the numerical values ​​before and after "~" as the minimum and maximum values, respectively. In addition, in the numerical ranges described in stages in this embodiment, the upper limit or lower limit described in a certain numerical range may be replaced with the upper limit or lower limit of another numerical range described in stages.

[0020] 1, a vehicle 100 according to this embodiment is, as an example, an electric vehicle (BEV: Battery Electric Vehicle) with a battery pack 10 mounted under the floor. In the vehicle 100, a DC / DC converter 102, an electric compressor 104, and a PTC (Positive Temperature Coefficient) heater 106 are arranged in front of the battery pack 10. In addition, a motor 108, a gear box 110, an inverter 112, and a charger 114 are arranged behind the battery pack 10.

[0021] Therefore, the DC current output from the battery pack 10 is supplied to the electric compressor 104, the PTC heater 106, the inverter 112, etc. after the voltage is adjusted by the DC / DC converter 102. In addition, power is supplied to the motor 108 via the inverter 112, causing the rear wheels to rotate and the vehicle 100 to run.

[0022] A charging port 116 is provided on the right side at the rear of the vehicle 100. Therefore, when a charging plug of an external charging facility (not shown) is connected to the charging port 116, power is stored in the battery pack 10 via the charger 114.

[0023] The vehicle 100 shown in the figure is a rear-wheel drive vehicle with the motor 108 mounted at the rear, but is not limited to this and may be a front-wheel drive vehicle with the motor 108 mounted at the front. Also, the vehicle may be equipped with a pair of motors 108 mounted at the front and rear, or may be equipped with an in-wheel motor on each wheel. In other words, the arrangement and structure of each component constituting the vehicle 100 are not limited to the configuration described above.

[0024] The battery pack 10 includes a plurality of battery modules 11. In the present embodiment, as an example, ten battery modules 11 are provided. Specifically, five battery modules 11 are arranged on the right side of the vehicle 100 with their thickness directions extending in the front-rear direction, and five battery modules 11 are arranged on the left side of the vehicle 100 with their thickness directions extending in the front-rear direction. The battery modules 11 are electrically connected to each other.

[0025] 2, the battery module 11 is formed in a substantially rectangular parallelepiped shape with the vehicle width direction as the longitudinal direction. A case 30 as an outer shell of the battery module 11 is formed of an aluminum alloy. For example, the case 30 of the battery module 11 is formed by joining aluminum die-casting to both ends of an aluminum alloy extrusion material by laser welding or the like.

[0026] A pair of voltage terminals 12 and a connector 14 are provided at each of both ends of the battery module 11 in the vehicle width direction. A flexible printed circuit board 21, which will be described later, is connected to the connector 14. In addition, bus bars (not shown) are welded to both ends of the battery module 11 in the vehicle width direction.

[0027] The length MW of the battery module 11 in the vehicle width direction is, for example, 350 mm to 600 mm, the length ML in the front-rear direction is, for example, 150 mm to 250 mm, and the height MH in the up-down direction is, for example, 80 mm to 110 mm.

[0028] 3, a plurality of battery cells 20 are arranged with their thickness direction oriented in the front-rear direction and housed inside the battery module 11. In the present embodiment, as an example, 24 battery cells 20 are arranged with their thickness direction oriented in the front-rear direction and bonded to one another.

[0029] A flexible printed circuit (FPC) 21 is disposed above the battery cells 20 and at the center in the front-rear direction. The flexible printed circuit 21 is formed in a strip shape with its longitudinal direction aligned with the vehicle width direction, and a thermistor 23 is provided at each end of the flexible printed circuit 21. The thermistor 23 is not bonded to the battery cells 20, and is configured to be pressed toward the battery cells 20 by the upper lid of the battery module 11.

[0030] One or more cushioning materials (not shown) are housed inside the battery module 11. The cushioning materials are, for example, elastically deformable thin plate-like members, and are arranged between adjacent battery cells 20 with the arrangement direction of the battery cells 20 being the thickness direction. In the present embodiment, as an example, cushioning materials are arranged at both ends of the battery module 11 in the longitudinal direction and in the central portion in the longitudinal direction.

[0031] 4, the battery cell 20 is formed in a substantially rectangular plate shape and houses an electrode body (not shown) inside. The electrode body is configured by laminating electrodes (negative and positive electrodes) and a separator disposed between the electrodes, and is sealed with a laminate film 22 as an exterior body.

[0032] The electrode may be, for example, a current collector having a layer containing an electrode active material formed on one or both sides thereof. The separator may be, for example, a microporous membrane made of a resin such as polyethylene. The laminate film 22 is a laminate having a metal layer containing a metal such as aluminum and a heat seal layer.

[0033] In this embodiment, as an example, the embossed sheet-like laminate film 22 is folded and the heat seal layer at the periphery is bonded to form the housing for the electrode body. The laminate film 22 can have either a single cup embossed structure in which one part is embossed, or a double cup embossed structure in which two parts are embossed. Figure 4 shows a single cup embossed structure with a drawing depth of about 8 mm to 10 mm.

[0034] 4 is folded back, and the peripheral portion 24 at the lower end of the battery cell 20 is also folded forward or backward as shown in Figures 5(A) and 5(B). A metal layer is exposed from the lower end surface (tip surface) 24A of the peripheral portion 24 at this lower end.

[0035] Furthermore, terminals (tabs) 26 are provided at both ends in the longitudinal direction of the battery cell 20. In this embodiment, as an example, each terminal 26 is provided at approximately the center in the vertical direction of the battery cell 20, but the positions of each terminal 26 are not limited to this, and each terminal 26 may be provided at a position offset above or below the approximately center in the vertical direction. Furthermore, each terminal 26 is joined to a bus bar (not shown) by laser welding or the like.

[0036] The length CW1 of the battery cell 20 in the vehicle width direction is, for example, 530 mm to 600 mm, 600 mm to 700 mm, 700 mm to 800 mm, 800 to 900 mm, 1000 mm or more, and the length CW2 of the area in which the electrode body is housed is, for example, 500 mm to 520 mm, 600 mm to 700 mm, 700 mm to 800 mm, 800 to 900 mm, 1000 mm or more.

[0037] The height CH of the battery cells 20 is, for example, 80 mm to 110 mm, or 110 mm to 140 mm. The thickness of the battery cells 20 is 5.0 mm to 7.0 mm, 7.0 mm to 9.0 mm, or 9.0 mm to 11.0 mm, and the height TH of the terminals 26 is 40 mm to 50 mm, 50 mm to 60 mm, or 60 mm to 70 mm.

[0038] Next, the internal structure of the battery module 11 configured as above will be described in more detail.

[0039] First Embodiment First, the first embodiment will be described. As shown in Fig. 5(A), at least the bottom wall 32 of the case 30 of the battery module 11 has a double structure, and has an outer wall 34 and an inner wall 36 of a predetermined thickness. The upper surface of the inner wall 36 is filled with a potting material 16 as a thermally conductive material to a predetermined height.

[0040] That is, the multiple battery cells 20 are housed in the case 30 with the peripheral portion 24 at the lower end folded forward or backward, and the potting material 16 is filled to a height at least sufficient to immerse the entire folded peripheral portion 24. Therefore, the metal layer exposed from the peripheral portion 24 of each battery cell 20 is in contact with the potting material 16. This allows heat inside each battery cell 20 to be dissipated from the metal layer through the potting material 16 to the outside.

[0041] Note that, for example, the terminals 26 (see FIG. 4) of the four battery cells 20 shown in FIG. 5(A) are arranged in the order of negative, positive, negative, and positive from the front side to the front side of the page. In other words, the terminals 26 are arranged in the order of positive, negative, positive, and negative from the front side to the back side of the page.

[0042] The four battery cells 20 have their peripheral edges 24 folded forward, backward, forward, and backward, for example, starting from the front side. Although not shown, the multiple battery cells 20 housed in the case 30 are formed so that the metal layer constituting the laminate film 22 is thicker at the center side in the stacking direction than at both end sides in the stacking direction.

[0043] Next, the operation of the battery module 11 according to the first embodiment configured as above will be described.

[0044] As shown in Figure 5(A), the metal layer exposed from the peripheral portion 24 of the multiple battery cells 20 housed within the case 30 in a stacked state in the thickness direction is in contact with the potting material 16 that is filled within the case 30 and provided at a predetermined height on the upper surface of the inner wall 36 of the bottom wall 32.

[0045] Therefore, the metal layer constituting the laminate film 22 can function as a heat dissipation material for the potting material 16, and can efficiently dissipate heat from inside each battery cell 20. In other words, the potting material 16, which is in direct contact with the metal layer, can sufficiently ensure heat dissipation from the inside to the outside of each battery cell 20 (improving cooling efficiency).

[0046] Moreover, the thickness of the metal layer of each battery cell 20 housed in the case 30 is thicker at the center side of the stacking direction of each battery cell 20 than at both end sides in the stacking direction. Here, it is known that in a stack formed by stacking a plurality of battery cells 20, the temperature tends to rise more easily toward the center side in the stacking direction, and it is known that the thicker the metal layer, the higher its thermal conductivity. Therefore, it is possible to improve the heat dissipation at the center side in the stacking direction where the temperature tends to rise, and it is possible to efficiently (well-balancedly) ensure the heat dissipation from the inside to the outside of each battery cell 20 housed in the case 30 in the stacking direction.

[0047] (Modification) The folding method of the peripheral portion 24 of each battery cell 20 is not limited to the folding method shown in Fig. 5(A) and may be, for example, the folding method shown in Fig. 5(B). That is, the terminals 26 (see Fig. 4) of the four battery cells 20 shown in Fig. 5(B) are arranged in order from the front to the front side of the paper as negative, negative, positive, and positive, and from the front to the back side of the paper as positive, positive, negative, and negative.

[0048] The four battery cells 20 have their peripheral portions 24 bent rearward, forward, rearward, and forward, starting from the front. Therefore, in this case, even if the metal layers exposed from the peripheral portions 24 of the battery cells 20 face each other in the front-to-rear direction (stacking direction), the metal layers have the same potential, and therefore, even if the metal layers come into contact with each other, the risk of this occurring can be reduced.

[0049] <Second embodiment> Next, a second embodiment will be described. Note that the same reference numerals are used to designate the same parts as those in the first embodiment, and detailed descriptions thereof will be omitted as appropriate.

[0050] As shown in FIG. 6, in the second embodiment, a recess 38 (groove portion) that is rectangular in plan view and extends in the longitudinal direction (vehicle width direction) is formed in an inner wall 36 of a bottom wall 32 of the case 30, and the only difference from the first embodiment is that the peripheral portion 24 of each battery cell 20 contained within the case 30 is inserted into the recess 38 without being folded.

[0051] The recess 38 shown in the figure is composed of a through hole 36A having a rectangular shape in plan view formed in the inner wall 36 and the upper surface of the outer wall 34, but is not limited to this, and the recess 38 may be configured to be formed to a predetermined depth in the upper surface of the inner wall 36. Furthermore, the inside of the recess 38 is inevitably filled with the potting material 16. Therefore, the metal layer exposed from each peripheral portion 24 is configured to come into contact with the potting material 16 inside each recess 38.

[0052] Moreover, each recess 38 houses the peripheral portions 24 of two adjacent battery cells 20. The lower end faces 24A (see FIG. 4) of the peripheral portions 24 housed inside each recess 38 are located on the same plane. In other words, in the process of manufacturing the battery cells 20, the tips of the peripheral portions 24 of each battery cell 20 are cut off all at once, so that the lengths (heights) of the peripheral portions 24 housed in each recess 38 are uniform.

[0053] In addition, the terminals 26 (see FIG. 4) of the four battery cells 20 shown in FIG. 6 are arranged in the same order as in FIG. 5(A), from the front side to the front of the paper, as negative pole, positive pole, negative pole, positive pole, and from the front side to the back of the paper, as positive pole, negative pole, positive pole, negative pole, but are not limited to this and may be arranged in the same order as in FIG. 5(B).

[0054] Next, the operation of the battery module 11 according to the second embodiment configured as above will be described. Note that the explanation of the operation common to the first embodiment will be omitted as appropriate.

[0055] 6, an inner wall 36 of the bottom wall 32 of the case 30 is formed with a plurality of recesses 38 capable of housing the peripheral portion 24 and potting material 16 of each battery cell 20. The metal layer exposed from the peripheral portion 24 of each battery cell 20 is in contact with the potting material 16 inside the recesses 38. This makes it possible to sufficiently ensure heat dissipation from the inside of each battery cell 20 to the outside, and also makes it possible to fix the position of each battery cell 20 housed in the case 30, thereby stabilizing the attitude of each battery cell 20.

[0056] Furthermore, since each recess 38 houses each peripheral portion 24 of two adjacent battery cells 20, the volumetric efficiency of each battery cell 20 relative to the case 30 can be improved and the size of the battery module 11 can be made more compact than in a configuration in which each recess 38 houses only one peripheral portion 24 of each battery cell 20.

[0057] Furthermore, the lower end surfaces 24A of the peripheral portions 24 housed within each recess 38 are located on the same plane, and the lengths (heights) of the peripheral portions 24 housed within each recess 38 of each battery cell 20 are uniform. This makes it possible to increase the volumetric efficiency of each battery cell 20 relative to the case 30, and further stabilize the attitude of each battery cell 20.

[0058] The above describes the battery module 11 according to this embodiment with reference to the drawings. However, the battery module 11 according to this embodiment is not limited to the one shown in the drawings, and the design can be modified as appropriate within the scope of the gist of the present invention.

[0059] For example, the metal layer in the peripheral portion 28 of the laminate film 22 is not limited to being exposed from the end surface 28A, and may be exposed from other portions in the peripheral portion 28. The case 30 does not have to have a double structure. In that case, in the second embodiment, for example, the thickness of the outer wall 34 in the bottom wall 32 may be made thick, and a recess 38 of a predetermined depth may be formed in the upper surface of the outer wall 34.

[0060] Furthermore, the type and size of the electrode body are not particularly limited, and are selected according to the scale and application of the battery cell 20. Furthermore, the number of electrodes and separators included in the electrode body are also not particularly limited, and are selected according to the scale and application of the battery cell 20. Furthermore, the vehicle 100 is not limited to an electric vehicle. The vehicle 100 may be, for example, a hybrid vehicle (HV) or a plug-in hybrid electric vehicle (PHEV) equipped with an engine. [Explanation of symbols]

[0061] 11 Battery module 16 Potting material (thermal conductive material) 20 Battery Cells 22 Laminating film 24 Periphery 24A Lower end surface (tip surface) 30 cases 36 Inner wall 38 Recess

Claims

1. a plurality of battery cells each having a laminate film including a metal layer and a heat seal layer, housing an electrode assembly therein and having a periphery of the heat seal layer joined thereto; a case in which the battery cells are housed in a stacked state in a thickness direction; a thermally conductive material provided on an inner wall of the case so as to be in contact with the metal layer exposed from the peripheral portion, the thermally conductive material dissipating heat from the battery cell; A battery module comprising:

2. a plurality of recesses capable of accommodating the peripheral portion and the thermally conductive material are formed in an inner wall of the case; The battery module according to claim 1 , wherein the metal layer exposed from the peripheral portion is in contact with the thermally conductive material inside the recess.

3. The battery module according to claim 2 , wherein each of the recesses accommodates the peripheral edges of two adjacent battery cells.

4. The battery module according to claim 3 , wherein a tip surface of the peripheral portion accommodated inside the recess is positioned on the same plane.

5. The battery module according to any one of claims 1 to 4, wherein the thickness of the metal layer of the battery cells housed in the case is formed to be thicker at a center side in a stacking direction than at both end sides in the stacking direction.

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