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 Art

[0002] A battery module (battery module) constructed in a structure that promotes heat dissipation by heat conduction through at least a part where electrode terminals are not arranged in a sealed portion of a battery case (case) of a battery cell (battery cell) has been conventionally known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, if the heat conductive member is a dedicated member separate from the member constituting the battery cell, the heat conduction path when releasing the heat inside the battery cell to the outside becomes discontinuous inside the battery cell, and there is a possibility that the heat dissipation property from the inside of the battery cell to the outside becomes insufficient.

[0005] Therefore, an object of the present invention is to obtain a battery module that can sufficiently ensure the heat dissipation property from the inside to the outside of the battery cell.

Means for Solving the Problems

[0006] To achieve the above objective, a battery module according to a first aspect of the present invention comprises a plurality of battery cells having a laminate film comprising a metal layer and a heat seal layer, and having electrode bodies housed in a laminate film with the heat seal layer at its peripheral edge joined; a case in which the battery cells are housed in a stacked state in the thickness direction; and a heat conductive material provided on the inner wall of the case so as to contact the metal layer exposed from the peripheral edge, and for dissipating heat from the battery cells.

[0007] According to the first embodiment of the invention, a plurality of battery cells have a laminate film comprising a metal layer and a heat-seal layer. The laminate film houses electrode bodies, and the heat-seal layer is joined to its peripheral edge. The plurality of battery cells are housed in a case in a stacked state in the thickness direction, and a heat-conducting material is provided on the inner wall of the case that contacts the metal layer exposed from each peripheral edge. This allows heat to be dissipated from the battery cells. In other words, sufficient heat dissipation from the inside to the outside of the battery cells is ensured by the heat-conducting material that is in direct contact with the metal layer of the laminate film.

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

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

[0010] Furthermore, a third embodiment of the present invention is a battery module of the second embodiment, wherein each recess accommodates the peripheral edges of two adjacent battery cells.

[0011] According to the third embodiment of the invention, each recess accommodates the peripheral portions of two adjacent battery cells. Therefore, compared to a configuration in which one peripheral portion of each battery cell is accommodated in each recess, the volumetric efficiency of each battery cell relative to the case is improved.

[0012] Furthermore, a fourth embodiment of the present invention is a battery module of the second or third embodiment, wherein the leading edge surface of the peripheral portion housed inside the recess is configured to be located on the same plane.

[0013] According to the fourth embodiment of the invention, the leading surfaces of the peripheral portions housed inside the recesses are located on the same plane. In other words, the lengths of the peripheral portions housed inside the recesses are uniform in each battery cell. Therefore, the volumetric efficiency of each battery cell relative to the case is increased, and the orientation of each battery cell is further stabilized.

[0014] Furthermore, a fifth embodiment of the present invention is a battery module according to any one of the first to fourth embodiments, wherein the battery cell housed in the case has a metal layer that is thicker on the central side in the stacking direction than on the ends in the stacking direction.

[0015] According to the fifth embodiment of the invention, the thickness of the metal layer of each battery cell housed in the case is such that the central part of each battery cell in the stacking direction is thicker than the ends in the stacking direction. Here, it is known that in a laminate formed by stacking multiple battery cells, the temperature tends to rise more easily towards the central part in the stacking direction, and it is known that the greater the thickness of the metal layer, the higher its thermal conductivity. Therefore, efficient heat dissipation from the inside to the outside of each battery cell is ensured in the stacking direction. [Effects of the Invention]

[0016] As described above, according to the present invention, sufficient heat dissipation from the inside to the outside of the battery cell can be ensured. [Brief explanation of the drawing]

[0017] [Figure 1]It is a schematic plan view showing an electric vehicle equipped with a battery module according to this embodiment. [Figure 2] It is a schematic perspective view showing the configuration of the battery module according to this embodiment. [Figure 3] It is a schematic plan view showing the configuration of the battery module according to this embodiment with the upper lid removed. [Figure 4] It is a schematic front view showing the configuration of the battery cell housed in the battery module according to this embodiment as viewed from the thickness direction. [Figure 5] (A) It is a schematic cross-sectional view showing the internal structure of the battery module according to the first embodiment as viewed from the vehicle width direction. (B) It is a schematic cross-sectional view showing the internal structure of the battery module according to a modification of the first embodiment as viewed from the vehicle width direction. [Figure 6] It is a schematic cross-sectional view showing the internal structure of the battery module according to the second embodiment as viewed from the vehicle width direction.

Mode for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described in detail based on the drawings. For the sake of convenience of explanation, in each figure, the arrow UP shown as appropriate is the upward direction of the vehicle, the arrow FR is the forward direction of the vehicle, and the arrow LH is the leftward direction of the vehicle. Therefore, in the following description, when the directions of up and down, front and back, and left and right are described without special mention, they indicate up and down in the vehicle up and down direction, front and back in the vehicle front and back direction, and left and right in the vehicle left and right direction (vehicle width direction). Also, the left and right directions are synonymous with the vehicle width direction.

[0019] Also, the sizes of the members in each figure are conceptual, and the relative relationships of the sizes between the members are not limited to this. In this embodiment, the numerical range indicated by "~" means a range including the numerical values described before and after "~" as the minimum value and the maximum value, respectively. Also, in the numerical ranges described step by step in this embodiment, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the upper limit value or the lower limit value of the numerical range described in other step-by-step descriptions.

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

[0021] Therefore, the direct 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. Also, when power is supplied to the motor 108 via the inverter 112, the rear wheels rotate and the vehicle 100 travels.

[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] Note that the illustrated vehicle 100 is a rear-wheel drive vehicle with the motor 108 mounted at the rear, but it is not limited to this, and it may be a front-wheel drive vehicle with the motor 108 mounted at the front. Also, it may be a vehicle with a pair of motors 108 mounted front and rear, or a vehicle equipped with in-wheel motors for each wheel. That is, the arrangement and structure of each component constituting the vehicle 100 are not limited to the above-described configuration.

[0024] The battery pack 10 is composed of multiple battery modules 11. In this embodiment, as an example, 10 battery modules 11 are provided. Specifically, 5 battery modules 11 are arranged on the right side of the vehicle 100 with their thickness in the front-rear direction, and 5 battery modules 11 are arranged on the left side of the vehicle 100 with their thickness in the front-rear direction. Each battery module 11 is electrically connected.

[0025] As shown in Figure 2, the battery module 11 is formed in a substantially rectangular parallelepiped shape with the vehicle width direction as the longitudinal direction. The case 30, which serves as the outer shell of the battery module 11, is made of aluminum alloy. For example, the case 30 of the battery module 11 is formed by joining aluminum die-cast parts to both ends of an aluminum alloy extruded material by laser welding or the like.

[0026] A pair of voltage terminals 12 and a connector 14 are provided at 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, busbars (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-to-back direction is, for example, 150 mm to 250 mm, and the height MH in the vertical direction is, for example, 80 mm to 110 mm.

[0028] As shown in Figure 3, multiple battery cells 20 are housed inside the battery module 11, arranged with their thickness in the front-to-back direction. In this embodiment, as an example, 24 battery cells 20 are arranged with their thickness in the front-to-back direction and bonded to one another.

[0029] A flexible printed circuit board (FPC) 21 is positioned above the battery cell 20, towards the center in the front-to-rear direction. The flexible printed circuit board 21 is formed in a strip shape with the vehicle width direction as its longitudinal direction, and thermistors 23 are provided at both ends of the flexible printed circuit board 21. The thermistors 23 are not bonded to the battery cell 20, but are pressed toward the battery cell 20 by the upper cover of the battery module 11.

[0030] Furthermore, one or more cushioning materials (not shown) are housed inside the battery module 11. The cushioning material is, for example, an elastically deformable thin plate-like member, and is arranged between adjacent battery cells 20 with the arrangement direction of the battery cells 20 as the thickness direction. In this embodiment, as an example, cushioning material is arranged at both ends in the longitudinal direction and in the longitudinal center of the battery module 11.

[0031] As shown in Figure 4, the battery cell 20 is formed in a roughly rectangular plate shape and houses an electrode body (not shown) inside. The electrode body is constructed by laminating electrodes (negative electrode and positive electrode) and a separator placed between the electrodes, and is sealed with a laminate film 22 as an outer casing.

[0032] As electrodes, for example, a current collector is used in which a layer containing electrode active material is formed on one or both sides. As separators, for example, a microporous film made of a resin such as polyethylene is used. 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, an embossed sheet-like laminate film 22 is folded and the heat-sealed layer at its peripheral edge is bonded together to form the electrode housing. The laminate film 22 can be of either a single-cup embossed structure with one embossed area or a double-cup embossed structure with two embossed areas. Figure 4 shows a single-cup embossed structure with a fold depth of approximately 8 mm to 10 mm.

[0034] Furthermore, the lower ends of the peripheral edges at both longitudinal ends of the battery cell 20 shown in Figure 4 are bent, and the peripheral edge 24 at the lower end of the battery cell 20 is also bent 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 edge 24 at the lower end.

[0035] Furthermore, terminals (tabs) 26 are provided at both longitudinal ends of the battery cell 20. In this embodiment, as an example, each terminal 26 is provided approximately in the center in the vertical direction of the battery cell 20, but each terminal 26 is not limited to this position and may be provided at a position offset above or below the approximately center in the vertical direction. In addition, each terminal 26 is joined to a busbar (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, 530mm to 600mm, 600mm to 700mm, 700mm to 800mm, 800mm to 900mm, and 1000mm or more, and the length CW2 of the region in which the electrode body is housed is, for example, 500mm to 520mm, 600mm to 700mm, 700mm to 800mm, 800mm to 900mm, and 1000mm or more.

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

[0038] The internal structure of the battery module 11, which has the configuration described above, will now be explained in more detail.

[0039] <First Embodiment> First, the first embodiment will be described. As shown in Figure 5(A), at least the bottom wall 32 of the case 30 of the battery module 11 has a double structure, having 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 heat conductive material to a predetermined height.

[0040] In other words, the multiple battery cells 20 are housed in the case 30 with their lower peripheral edges 24 folded forward or backward, and the potting material 16 is filled to a height such that at least the entire folded peripheral edge 24 is submerged. Therefore, the metal layer exposed from the peripheral edge 24 of each battery cell 20 comes into contact with the potting material 16. This allows the heat inside each battery cell 20 to be dissipated to the outside through the metal layer and the potting material 16.

[0041] In the four battery cells 20 shown in Figure 5(A), each terminal 26 (see Figure 4) is arranged such that, for example, from the front, the terminals closest to the viewer on the page are negative, positive, negative, and positive. That is, from the front, the terminals closest to the viewer on the page are positive, negative, positive, and negative.

[0042] The four battery cells 20 are, for example, folded in order from the front, to the front, then to the rear, then to the front, then to the rear, with their peripheral edges 24 bent in that order. Although not shown in the illustration, the metal layer constituting the laminate film 22 is formed thicker on the central side in the stacking direction of the multiple battery cells 20 housed in the case 30 than on the ends in the stacking direction.

[0043] The operation of the battery module 11 according to the first embodiment, which has the configuration described above, will now be explained.

[0044] As shown in Figure 5(A), the metal layers exposed from the peripheral edges 24 of the multiple battery cells 20 housed in the case 30 in a stacked state in the thickness direction are in contact with the potting material 16 that is filled inside 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, allowing for efficient heat dissipation from inside each battery cell 20. In other words, the potting material 16, which is in direct contact with the metal layer, ensures sufficient heat dissipation from the inside to the outside of each battery cell 20 (improving cooling efficiency).

[0046] Furthermore, the thickness of the metal layer of each battery cell 20 housed in the case 30 is greater towards the center in the stacking direction than towards both ends in the stacking direction. It is known that in a laminate formed by stacking multiple battery cells 20, the temperature tends to rise more easily towards the center in the stacking direction, and it is known that the greater the thickness of the metal layer, the higher its thermal conductivity. Therefore, the heat dissipation of the central part in the stacking direction, where the temperature tends to rise more easily, can be improved, and the heat dissipation from the inside to the outside of each battery cell 20 housed in the case 30 can be efficiently (balanced) ensured in the stacking direction.

[0047] (modified version) Note that the way the peripheral portion 24 of each battery cell 20 is folded is not limited to the folding method shown in Figure 5(A), but may also be folded as shown in Figure 5(B), for example. That is, in the four battery cells 20 shown in Figure 5(B), the terminals 26 (see Figure 4) on the front side of the paper are arranged as follows: negative terminal, negative terminal, positive terminal, positive terminal, and positive terminal, and the terminals on the back side of the paper are arranged as follows: positive terminal, positive terminal, negative terminal, negative terminal, and negative terminal, from front to back.

[0048] The peripheral edges 24 of the four battery cells 20 are bent backward, forward, backward, and forward in order from the front. Therefore, in this case, even if the metal layers exposed from the peripheral edges 24 of the battery cells 20 face each other in the front-to-back direction (stacking direction), the metal layers will be at the same potential, so even if the metal layers come into contact with each other, the risk caused by this can be reduced.

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

[0050] As shown in Figure 6, this second embodiment differs from the first embodiment in that a rectangular recess 38 (groove) in plan view, extending in the longitudinal direction (vehicle width direction), is formed in the inner wall 36 of the bottom wall 32 of the case 30, and the peripheral edges 24 of each battery cell 20 housed in the case 30 are inserted into the recess 38 without being bent.

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

[0052] Furthermore, each recess 38 accommodates the peripheral edges 24 of two adjacent battery cells 20. The lower end surfaces 24A (see Figure 4) of each peripheral edge 24 housed inside each recess 38 are located on the same plane. In other words, during the manufacturing process of the battery cells 20, the tips of the peripheral edges 24 of each battery cell 20 are cut together, so that the length (height) of each peripheral edge 24 housed inside each recess 38 is uniform.

[0053] Furthermore, in the four battery cells 20 shown in Figure 6, each terminal 26 (see Figure 4) is arranged in the same way as in Figure 5(A), with the front side facing the viewer being the negative terminal, positive terminal, negative terminal, and the back side facing the viewer being the positive terminal, negative terminal, positive terminal, negative terminal. However, it is not limited to this arrangement and may be the same as in Figure 5(B).

[0054] The operation of the battery module 11 according to the second embodiment, which has the configuration described above, will now be explained. Note that the explanation of operations common to the first embodiment will be omitted as appropriate.

[0055] As shown in Figure 6, the inner wall 36 of the bottom wall 32 of the case 30 has a plurality of recesses 38 that can accommodate the peripheral edge 24 of each battery cell 20 and the potting material 16. The metal layer exposed from the peripheral edge 24 of each battery cell 20 is in contact with the potting material 16 inside the recess 38. Therefore, sufficient heat dissipation from the inside to the outside of each battery cell 20 can be ensured, and the position of each battery cell 20 housed in the case 30 can be fixed, stabilizing the orientation of each battery cell 20.

[0056] Furthermore, since each recess 38 accommodates the peripheral edges 24 of two adjacent battery cells 20, compared to a configuration where each recess 38 accommodates only one peripheral edge 24 of each battery cell 20, the volumetric efficiency of each battery cell 20 relative to the case 30 can be increased, and the size of the battery module 11 can be made more compact.

[0057] Furthermore, the lower end surfaces 24A of each peripheral edge 24 housed inside each recess 38 are located on the same plane, and the lengths (heights) of each peripheral edge 24 housed inside each recess 38 are the same in each battery cell 20. Therefore, the volumetric efficiency of each battery cell 20 relative to the case 30 can be increased, and the orientation of each battery cell 20 can be further stabilized.

[0058] The battery module 11 according to this embodiment has been described above based on the drawings, but the battery module 11 according to this embodiment is not limited to the illustrated one, and can be modified as appropriate without departing from the spirit of the present invention.

[0059] For example, the metal layer at the peripheral edge 28 of the laminate film 22 is not limited to being exposed from its end face 28A, but may be exposed from other parts of the peripheral edge 28. Also, the case 30 does not have to be a double-layered structure. In that case, for example, the thickness of the outer wall 34 of the bottom wall 32 may be increased, and a recess 38 of a predetermined depth may be formed on 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. Similarly, the number of electrodes and separators included in the electrode body are not particularly limited and are selected according to the scale and application of the battery cell 20. Moreover, the vehicle 100 is not limited to an electric vehicle. For example, the vehicle 100 may be a hybrid vehicle (HV) or a plug-in hybrid electric vehicle (PHEV) equipped with an engine. [Explanation of symbols]

[0061] 11 Battery Modules 16. Potting material (thermal conductive material) 20 battery cells 22 Laminating film 24 Peripheral area 24A Lower end surface (tip surface) 30 cases 36 Inner wall 38 recesses

Claims

1. Multiple battery cells having a laminate film comprising a metal layer and a heat-seal layer, with the electrode body being housed and the heat-seal layer at the periphery being joined; A case in which the aforementioned battery cells are housed in a stacked state in the thickness direction, A heat conductive material is provided on the inner wall of the case so as to be in contact with the metal layer exposed from the peripheral edge, and which dissipates heat from the battery cell. Equipped with, The battery module, housed in the case, has a metal layer that is thicker at the center of the stacking direction than at both ends of the stacking direction.

2. Multiple recesses capable of accommodating the peripheral portion and the heat conductive material are formed in the 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 thermal conductive material inside the recess.

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

4. The battery module according to claim 3, wherein the tip surface of the peripheral portion housed inside the recess is configured to be located on the same plane.

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