Battery pack

Abstract

This prevents a decrease in cooling efficiency for stacked battery cells. [Solution] The battery pack 10 has a band body 24 that restrains the battery cells 12 between the battery stack 16 and a cooler 22 for cooling the battery cells 12 of the battery stack 16. In addition, the battery pack 10 has a plurality of heat conductive sheets 32 placed between the battery cells 12 and the band body 24, and between the cooler 22 and the band body 24. Between the battery cells 12 and the band body 24, one end 36 of the curved heat conductive sheet 32 ​​is in surface contact with the battery cell 12 and joined, and the other end 36 is in surface contact with the band body 24 and joined. As a result, even if the band body 24 bends or the like and the distance between the battery cells 12 and the band body 24 changes, the heat conductive sheet 32 ​​follows and elastically deforms, so that a decrease in cooling efficiency for the stacked battery cells 12 can be suppressed.

Description

[Technical Field]

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

[0002] The battery module disclosed in Patent Document 1 includes battery cells using laminated lithium secondary batteries or the like, plates made of a material that can conduct heat to the battery cells, and a heat exchanger that exchanges heat between the plates. Furthermore, in the battery module, a thermal diffusion sheet made of a graphite sheet or the like is interposed between the battery cells and the plates, and in the battery module, the thermal diffusion sheet diffuses the heat from the battery cells, thereby suppressing the occurrence of temperature differences between the battery cells. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-218930 Summary of the Invention [Problem to be solved by the invention]

[0004] In a battery pack in which multiple battery cells are stacked, a restraint band made of iron or the like is provided on one surface in a direction intersecting the stacking direction, and the restraint band restrains the stacked battery cells. In addition, in a battery pack, a cooler for cooling each battery cell is sometimes disposed on the surface on which the restraint band is disposed. In such a battery pack, a thermally conductive material is attached between each battery cell and the restraint band and the cooler, or between the restraint band and the cooler. In this way, in the battery pack, heat generated in each battery cell during charging and discharging is transferred to the cooler via the thermally conductive material and dissipated from the cooler, thereby cooling each battery cell.

[0005] However, in a battery pack, because the restraint bands prevent the stack from changing in length in the stacking direction, expansion and contraction of each battery cell during charging and heat dissipation can cause undulations on the surfaces of the restraint bands and stack in a direction intersecting the stacking direction. This raises the concern that the thermally conductive material in the battery pack may peel off or crack from the battery cells, restraint bands, or cooler, and this peeling of the thermally conductive material from the battery cells, restraint bands, or cooler can reduce the cooling efficiency of the battery cells and degrade battery performance.

[0006] This invention has been made in view of the above facts, and aims to provide a battery pack in which the decrease in cooling efficiency for stacked battery cells is suppressed. [Means for solving the problem]

[0007] In order to achieve the above object, a first aspect of the battery pack of the present invention includes: a stack in which a plurality of battery cells are stacked in a stacking direction; a cooling member arranged opposite at least one surface of the stack in a direction intersecting the stacking direction and for cooling each of the battery cells on that one surface; a band-shaped restraining member arranged between the stack and the cooling member and pressurizing the stack at both ends in the stacking direction to restrain each of the battery cells; and a heat conduction portion in which a sheet-shaped heat conduction member is arranged between the battery cells and the cooling member, with one side in the planar direction joined to the battery cell side and the other side joined to the cooling member side and with an intermediate portion curved and deformed, and heat is conducted between the battery cells and the cooling member via the heat conduction member.

[0008] The battery pack of the first aspect includes a stack of multiple battery cells stacked in a stacking direction, a cooling member facing at least one surface of the stack in a direction intersecting the stacking direction, and the cooling member cools each of the battery cells on the facing surface. A restraining member is disposed between the stack and the cooling member, and the restraining member is formed in a strip shape and presses the stack at both ends in the stacking direction to restrain each of the battery cells.

[0009] Furthermore, a thermally conductive member for conducting heat between the battery cells and the cooling member is disposed in the thermally conductive portion between the battery cells and the cooling member, and the thermally conductive member is formed in a sheet shape with one side bonded to the battery cells and the other side bonded to the cooling member, and a curved intermediate portion. When a restraining member is disposed between the battery cells and the cooling member, one side of the thermally conductive member is bonded to the battery cells and the other side is bonded to the restraining member. Furthermore, between the restraining member and the cooling member, one side of the thermally conductive member is bonded to the restraining member and the other side is bonded to the cooling member.

[0010] Therefore, even if the expansion and contraction of the battery cells causes the restraining member to bend, changing the distance between the battery cell and the restraining member or the distance between the restraining member and the cooling member, the thermal conduction member can deform to follow this change, preventing peeling or cracking at the joints of the thermal conduction member. This prevents a decrease in cooling efficiency for the battery cells and a decrease in battery performance.

[0011] In the battery pack of the second aspect, in the first aspect, the heat conduction section includes a heat conduction plate in which a plurality of the heat conduction members are arranged in the stacking direction of the battery cells, thermally connecting the plurality of the heat conduction members and conducting heat between the heat conduction members.

[0012] In the battery pack of the second aspect, a plurality of thermally conductive members are arranged in the thermal conduction section in the stacking direction of the battery cells. A thermally conductive plate is also arranged in the thermal conduction section, and the thermally conductive plate thermally connects the plurality of thermally conductive members and conducts heat between the thermally conductive members. This makes it possible to uniformize the temperature of the battery cells and effectively suppress a decrease in the cooling efficiency for the battery cells.

[0013] The battery pack of the third aspect is the battery pack of the first or second aspect, wherein the heat conduction members are arranged between the battery cells and the restraining members, and between the restraining members and the cooling member, and are elastically deformable in accordance with changes in the distance between the battery cells and the restraining members, and the distance between the restraining members and the cooling member.

[0014] In the battery pack of the third aspect, the thermally conductive members are disposed between the battery cells and the restraining members, and between the restraining members and the cooling member. The thermally conductive members are elastically deformable, and are elastically deformed in response to changes in the distance between the battery cells and the restraining members, and the distance between the restraining members and the cooling member. This prevents peeling and other problems from occurring at the joints of the thermally conductive members, and more effectively prevents a decrease in the cooling efficiency for the battery cells. [Effects of the Invention]

[0015] According to this disclosure, since a sheet-shaped heat conductive member is curved and deformed and placed between the battery cell and the cooling member, it is possible to suppress peeling or other damage to the heat conductive member, and the efficient cooling of the battery cell can be maintained. [Brief explanation of the drawings]

[0016] [Figure 1A] This is a schematic diagram of the battery pack as seen from the side according to the first embodiment. [Figure 1B] This is a schematic cross-sectional view of the main part of the battery pack along the line 1B-1B in Figure 1A. [Figure 2A] This is a schematic cross-sectional view of the main part of the battery pack according to Modification Example 1. [Figure 2B] This is a schematic cross-sectional view of the main part of the battery pack according to Modification 2. [Figure 3A] This is a schematic diagram of the battery pack as seen from the side, relating to Modification 3. [Figure 3B] This is a schematic cross-sectional view of the main part of the battery pack along the line 3B-3B in Figure 3A. [Figure 4A] This is a schematic diagram of a side view showing an example of a battery pack according to Modification 4. [Figure 4B] This is a schematic diagram of a side view showing another example of a battery pack according to Modification 4. [Figure 5A] This is a schematic diagram of the battery pack as seen from the side according to the second embodiment. [Figure 5B] This is a schematic cross-sectional view of the main part of the battery pack along the line 5B-5B in Figure 5A. [Figure 6A]FIG. 10 is a schematic configuration diagram of a main part of a battery pack according to a third embodiment, as seen from the side. [Figure 6B] 6B is a plan view showing a main part of the heat conduction plate as seen from the battery stack side in FIG. 6A. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A battery pack and a cooling structure for the battery pack according to embodiments of the present invention will be described in detail below with reference to the drawings. [First embodiment] FIG. 1A shows a schematic configuration diagram of a battery pack 10 according to the first embodiment as seen from the side, and FIG. 1B shows a schematic cross-sectional view of a main part of the battery pack 10 according to the first embodiment taken along line 1B-1B in FIG. 1A. In the drawing, one side of the stacking direction as one direction is indicated by arrow X, and one direction intersecting the stacking direction is indicated by arrow Z. In the following description, arrow Z is defined as the upward direction in the vertical direction of the battery pack 10. Furthermore, the direction intersecting the stacking direction and the vertical direction is defined as the width direction of the battery pack 10, and in the drawing, one side of the width direction is defined by arrow Y.

[0018] The battery pack 10, also called a battery assembly, is composed of one or more battery modules and is housed in a case (not shown). In the first embodiment, a battery pack 10 composed of one battery module will be described as an example.

[0019] The battery pack 10 is mounted, for example, in a vehicle equipped with an electric motor as a drive source for traveling, and outputs DC power that can be used to drive the electric motor. Vehicles that can mount the battery pack 10 include hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs).

[0020] As shown in Figure 1A, the battery pack 10 comprises a plurality of battery cells 12 and a pair of end plates 14. Each battery cell 12 has a required thickness and is substantially rectangular in shape when viewed in the stacking direction (thickness direction). Multiple battery cells 12 are arranged in the stacking direction to form a battery stack 16 as a stacked body. In the battery stack 16 of the battery pack 10, the plurality of battery cells 12 are connected in series or in parallel to enable the output of DC power at the required voltage.

[0021] The battery cell 12 is a secondary battery such as a lithium-ion battery. However, the battery cell 12 may be not limited to lithium-ion batteries, but may also be various other secondary batteries such as solid-state batteries, lead-acid batteries, nickel-cadmium batteries, and nickel-metal hydride batteries. Furthermore, the battery cell 12 may be not limited to secondary batteries, but may also be a primary battery such as a manganese dry cell, a lithium graphite fluoride primary battery, or a lithium manganese dioxide primary battery.

[0022] In the battery stack 16, one of a pair of end plates 14 is positioned on one side of the stacking direction of the battery cells 12, and the other is positioned on the other side of the stacking direction of the battery cells 12, and is stacked on top of the battery cells 12. In addition, inter-cell members 18 are positioned between adjacent battery cells 12 in the stacking direction, and between the battery cells 12 and the end plates 14 in the battery stack 16. The inter-cell members 18 use insulating materials, and the use of insulating materials in the inter-cell members 18 prevents the other battery cell 12 from overheating if one battery cell 12 becomes abnormally hot for some reason between two battery cells 12 adjacent to each other in the stacking direction. The inter-cell members 18 only need to be configured to suppress the temperature rise of the other cell due to heat transfer, and may include configurations that promote the cooling of the battery cells 12.

[0023] The battery pack 10 is equipped with a restraining band 20 as a restraining member and a cooler 22 as a cooling member for each of the battery cells 12. The restraining band 20 and the cooler 22 are positioned on the upper and lower surfaces of the battery stack 16, which are surfaces in a direction intersecting the stacking direction of the battery cells 12. The restraining band 20 is attached to the battery stack 16, and the cooler 22 is positioned above and below the restraining band 20.

[0024] In the first embodiment, as an example, the restraint bands 20 and the coolers 22 are arranged on the upper and lower surfaces of the battery stack 16, but the restraint bands 20 and the coolers 22 only need to be arranged on at least one surface in a direction intersecting the stacking direction, and may also be arranged on a lateral surface.

[0025] The restraint band 20 is made of a metal such as iron, which can withstand a high load. The restraint band 20 includes a band body 24 in the shape of a strip or strip plate, and bent portions 26 formed by bending both longitudinal ends of the band body 24.

[0026] The restraint band 20 is positioned such that its longitudinal direction is aligned with the stacking direction of the battery cells 12, with the band body 24 facing the battery stack 16, and each of its bent portions 26 abutting against the outer surface of the end plate 14 in the stacking direction. The restraint band 20 is also attached to the battery stack 16 and assembled into the battery pack 10 by fastening (or other fixing methods such as adhesive fixing) each of its bent portions 26 to the end plate 14.

[0027] The restraint band 20 restrains each of the battery cells 12 in the battery stack 16 by applying an external force between the pair of end plates 14 through each of the bent portions 26 in a direction that brings them closer to each other.

[0028] The cooler 22 is made of a metal material such as aluminum, which has high thermal conductivity, and the cooler 22 is cooled by a refrigerant that circulates with a cooling device (not shown). In the battery pack 10, heat exchange occurs between each of the battery cells 12 and the cooler 22, enabling heat dissipation from the battery cells 12.

[0029] On the other hand, the battery pack 10 has a heat conduction section 30 between the battery stack 16 and the cooler 22, and the heat conduction section 30 is responsible for heat conduction between each of the battery cells 12 of the battery stack 16 and the cooler 22. In the battery pack 10, the side of the battery stack 16 facing the cooler 22 is covered by the band body 24 of the restraint band 20. The heat conduction section 30 is defined as heat conduction section 30A between the battery stack 16 and the band body 24, and heat conduction section 30B between the cooler 22 and the band body 24.

[0030] A thermal conductive sheet 32 ​​is used as a thermal conductive member in each of the thermal conductive sections 30A and 30B. The thermal conductive sheet 32 ​​may be made of a metal member such as copper, and the metal member may be formed into a sheet. Furthermore, the thermal conductive sheet 32 ​​can be made of a material that has excellent thermal conductivity (high thermal conductivity) and elasticity. In the first embodiment, as an example, a graphite sheet is used for the thermal conductive sheet 32.

[0031] Graphite sheets are manufactured using graphite and possess not only high thermal conductivity in the thickness direction, but also superior thermal conductivity (thermal diffusivity) in the planar direction compared to silver, copper, aluminum, etc. Graphite sheets excel in planar thermal diffusivity. Furthermore, graphite sheets are lighter than metals and possess elasticity.

[0032] As shown in Figures 1A and 1B, the thermal conductive sheet 32 ​​is in the shape of a strip of the required thickness, with its longitudinal direction as the stacking direction, and is placed between the battery cells 12 of the battery stack 16 and the band body 24, and between the cooler 22 and the band body 24. In addition, multiple thermal conductive sheets 32 are placed in the width direction of the battery pack 10 in each of the spaces between the battery cells 12 of the battery stack 16 and the band body 24, and between the cooler 22 and the band body 24.

[0033] The thermally conductive sheet 32 ​​is bent at the middle in the width direction by elastic deformation, and is formed into a substantially U-shape when viewed in the longitudinal direction, and the thermally conductive sheet 32 ​​has a curved portion 34 formed at the middle in the width direction, and both end portions 36 on the width direction are connected by the curved portion 34. In other words, the thermally conductive sheet 32 ​​has a substantially U-shaped curved shape as a displacement absorbing structure for absorbing displacement in the arrangement spacing.

[0034] In the heat conduction section 30A between the battery cells 12 and the band main body 24, one end 36 of the heat conduction sheet 32 ​​is in surface contact with the battery cell 12, and the other end 36 is in surface contact with the band main body 24. In the heat conduction section 30B between the cooler 22 and the band main body 24, one end 36 of the heat conduction sheet 32 ​​is in surface contact with the cooler 22, and the other end 36 is in surface contact with the band main body 24. The end 36 of the heat conduction sheet 32 ​​is joined, for example, by adhesive bonding, in the surface contact area of ​​the battery cell 12, the cooler 22, or the band main body 24. As a result, in the battery pack 10, each of the battery cells 12 and the cooler 22 are thermally connected by the heat conduction sheet 32.

[0035] The battery pack 10 configured in this manner includes a battery stack 16 in which a plurality of battery cells 12 are stacked. In the battery pack 10, each battery cell 12 outputs DC power of a predetermined voltage when it discharges, and each battery cell 12 is charged when DC power is input. The battery cells 12 generate heat and their temperature rises when they are charged and discharged, but by maintaining the temperature within an appropriate temperature range, battery performance such as discharge performance and charge performance is maintained within an appropriate range.

[0036] In the battery pack 10, the battery stack 16 is restrained by restraint bands 20, and a cooler 22 is disposed. In the battery pack 10, a heat conductive part 30A is disposed between the battery stack 16 and the band main body 24 of the restraint band 20, and a heat conductive part 30B is disposed between the cooler 22 and the band main body 24.

[0037] A heat conductive sheet 32 ​​is used in the heat conductive sections 30A and 30B, and the heat conductive sheet 32 ​​thermally connects each battery cell 12 of the battery stack 16 to the cooler 22 via the band body 24. As a result, in the battery pack 10, heat from each battery cell 12 is transferred to the cooler 22 via the heat conductive sheet 32, and the heat generated by each battery cell 12 is transferred to the cooler 22 and dissipated. Therefore, in the battery pack 10, the temperature rise caused by the heat generated during charging and discharging of each battery cell 12 is suppressed, and a decrease in battery function is suppressed.

[0038] Furthermore, the thermal conductive sheet 32 ​​is made of graphite, which has high thermal conductivity in the planar direction, and the thermal conductive sheet 32 ​​is used so that heat conduction occurs in the width direction, which is one direction in the planar direction of the graphite sheet. As a result, the thermal conductive sheet 32 ​​can efficiently conduct heat between the battery cell 12 and the cooler 22, enabling efficient heat dissipation of the battery cell 12.

[0039] Incidentally, in the battery pack 10, the battery cells 12 may expand and contract during charging and discharging. When the battery cells 12 expand in the battery pack 10, the bent portions 26 of the restraint bands 20 receive a force (pressure) from the end plate 14 in a direction that causes them to move apart from each other. As a result, the band body 24 of the restraint bands 20 may bend upward or downward in a roughly convex shape, and when the band body 24 is bent in the battery pack 10, the distance between the battery cells 12 and the band body 24, and the distance between the cooler 22 and the band body 24, change.

[0040] In this case, if the deformation of the thermal conductive sheet 32 ​​in the battery pack 10 is suppressed (difficult to deform), the end portion 36 may peel off from the battery cell 12, the cooler 22, or the band body 24. In the battery pack 10, if the end portion 36 of the thermal conductive sheet 32 ​​peels off from the battery cell 12, the cooler 22, or the band body 24, the heat transfer efficiency between the battery cell 12 and the cooler 22 may decrease, resulting in a decrease in battery performance.

[0041] Here, the thermally conductive sheet 32 ​​is curved and deformed into a roughly U-shape when viewed in the longitudinal direction. Therefore, in the battery pack 10, even if the distance between the battery cells 12 and the band main body 24, and the distance between the cooler 22 and the band main body 24, changes, the thermally conductive sheet 32 ​​deforms to follow these changes. That is, when the distance between the end portions 36 on both sides is widened, the thermally conductive sheet 32 ​​deforms so that the curve of the curved portion 34 becomes gentler. On the other hand, when the distance between the end portions 36 on both sides is narrowed, the thermally conductive sheet 32 ​​deforms so that the curve of the curved portion 34 becomes stronger.

[0042] As a result, in the battery pack 10, even if the band body 24 of the restraint band 20 is bent, the end 36 of the thermally conductive sheet 32 ​​is prevented from peeling off from the battery cells 12, the cooler 22, or the band body 24. Therefore, in the battery pack 10, there is no decrease in the efficiency of heat conduction between the battery cells 12 and the cooler 22, and heat generation from the battery cells 12 can be efficiently suppressed using the cooler 22.

[0043] Furthermore, the thermally conductive sheet 32 ​​is made of a graphite sheet and is elastically deformable. This allows the thermally conductive sheet 32 ​​to elastically deform in response to changes in the distance between the battery cells 12 and the band body 24, and changes in the distance between the band body 24 and the cooler 22. In other words, if a material that is not prone to elastic deformation (a material that undergoes plastic deformation), such as a metal material, is used for the thermally conductive sheet 32, the widening of the distance between the pair of ends 36 could cause the ends 36 to peel off from the battery cells 12, the cooler 22, or the band body 24.

[0044] In contrast, in the battery pack 10, the thermally conductive sheet 32 ​​elastically deforms, preventing peeling at the end portions 36. As a result, in the battery pack 10, the use of the thermally conductive sheet 32 ​​in the thermally conductive portions 30A and 30B allows the battery cells 12 to maintain effective heat dissipation using the cooler 22.

[0045] Next, modifications of the first embodiment will be described with reference to the drawings. The basic configuration of each of the modifications described below is the same as that of the first embodiment.

[0046] [Variation 1] In the first embodiment, the thermally conductive sheet 32 ​​is curved in a substantially U-shape. However, the cross-sectional shape of the thermally conductive member is not limited to this. Fig. 2A shows a schematic cross-sectional view of a main part of a battery pack 10A according to a first modification, as viewed in the stacking direction.

[0047] 2A, in Modification 1, a thermally conductive sheet 40 is used as the thermally conductive member. The thermally conductive sheet 40 can be made of the same material as the thermally conductive sheet 32. The thermally conductive sheet 40 has a substantially circular (or elliptical) cross section cut along a direction intersecting the longitudinal direction, and the thermally conductive sheet 40 has a shape in which the end portions 36 of two thermally conductive sheets 32 are joined together.

[0048] In the battery pack 10A, a thermally conductive sheet 40 is disposed in place of the thermally conductive sheet 32 ​​of the battery pack 10. The thermally conductive sheet 40 is elastically deformed and curved into a substantially elliptical shape, so that it comes into surface contact with the battery cells 12, the cooler 22, or the band body 24, and each of the surface contact areas is joined.

[0049] In the battery pack 10A configured in this manner, the thermally conductive sheet 40 deforms in response to changes in the distance between the battery cells 12 and the band body 24, and also in response to changes in the distance between the cooler 22 and the band body 24. Therefore, the battery pack 10A using the thermally conductive sheet 40 can achieve the same effects as the battery pack 10 using the thermally conductive sheet 32.

[0050] The thermally conductive sheet 40 changes its dimension along the width direction of the battery stack 16 and its contact area in response to changes in the spacing between the battery cell 12 and the band main body 24 and the spacing between the cooler 22 and the band main body 24. Therefore, the thermally conductive sheet 40 can be arranged taking into consideration the contact area when the spacing is widened and the dimension when the spacing is narrowed.

[0051] [Variation 2] FIG. 2B shows a schematic cross-sectional view of the main part of a battery pack 10B according to Modification 2 as viewed in the stacking direction.

[0052] As shown in Figure 2B, in the modified example 2, a thermal conductive sheet 42 is used as a thermal conductive member, and the same material as the thermal conductive sheet 32 ​​can be used for the thermal conductive sheet 42. In addition, the thermal conductive sheet 42 has multiple folds in the middle section between the ends 36 on both sides in the width direction, and the thermal conductive sheet 42 has two folds in the middle section in the width direction. As a result, the thermal conductive sheet 42 has a roughly S-shape with two curved sections 44 formed between the ends 36.

[0053] In the battery pack 10B, a thermal conductive sheet 42 is placed in place of the thermal conductive sheet 32 ​​of the battery pack 10, and each of the ends 36 is joined by surface contact with one of the battery cells 12, the cooler 22, or the band body 24.

[0054] In the battery pack 10B configured in this way, the thermal conductive sheet 42 deforms in accordance with changes in the distance between the battery cell 12 and the band body 24, and also deforms in accordance with changes in the distance between the cooler 22 and the band body 24. For this reason, the battery pack 10B using the thermal conductive sheet 42 can achieve the same effect as the battery pack 10 using the thermal conductive sheet 32.

[0055] Furthermore, since the thermal conductive sheet 42 can have a wider width than the thermal conductive sheet 32, it can deform to accommodate larger changes in spacing than the thermal conductive sheet 32. In addition, the thermal conductive sheet 42 has multiple curved sections 44 between the ends 36, which suppresses changes in width when the spacing between a pair of ends 36 changes. As a result, the thermal conductive sheet 42 can be arranged at a narrower spacing than the thermal conductive sheets 32 and 40, thereby improving the heat conduction efficiency between the battery cells 12 and the cooler 22.

[0056] [Variation 3] In the first embodiment, multiple thermally conductive sheets 32 were arranged in the width direction of the battery stack 16, but the longitudinal direction of the thermally conductive members may be the width direction of the assembled battery, and multiple thermally conductive members may be arranged in the stacking direction of the battery cells in the assembled battery.

[0057] Figure 3A shows a schematic configuration of the battery pack 10C according to the modified example 3 in a side view, and Figure 3B shows a schematic cross-section of the main part of the battery pack 10C in a cross-sectional view along the line 3B-3B in Figure 3A.

[0058] As shown in Figures 3A and 3B, in the battery pack 10C, multiple thermal conductive sheets 32 are arranged in the thermal conductive section 50 between the battery stack 16 and the cooler 22. The thermal conductive sheets 32 are arranged in the thermal conductive section 50A between the battery stack 16 and the band body 24, and in the thermal conductive section 50B between the cooler 22 and the band body 24, with their longitudinal direction being the stacking direction, and multiple sheets are arranged in the width direction of the battery stack 16. In addition, each end 36 of the thermal conductive sheets 32 is in surface contact with the battery cell 12, the cooler 22, or the band body 24 and joined to it.

[0059] The battery pack 10C configured in this manner can also achieve the same effects as the battery pack 10. Note that in the battery pack 10C, instead of the thermally conductive sheet 32, thermally conductive sheets 40 and 42 may be arranged.

[0060] [Variation 4] In the first embodiment and in the 1st to 3rd modifications, thermal conductive sheets 32, 40, and 42 with displacement absorption structures are placed between the battery stack 16 and the band body 24, and between the cooler 22 and the band body 24, respectively. However, the thermal conductive members may be placed between the battery cell 12 and the band body 24, and between the cooler 22 and the band body 24, or at least one of the two.

[0061] Figure 4A shows a cross-sectional view of the main part of battery pack 10D, an example of a battery pack according to Modification 4, viewed in the stacking direction, and Figure 4B shows a cross-sectional view of the main part of battery pack 10E, another example of a battery pack according to Modification 4, viewed in the stacking direction. Note that Figures 4A and 4B are cross-sectional views similar to those in Figure 1B.

[0062] When joining one surface of a sheet-shaped thermally conductive member to the battery cell side and the other surface to the cooling member side, the curvature of the restraining member, etc., can significantly increase the gap between the battery cell or the cooling member, raising concerns about peeling, cracking, etc. In contrast, if the curvature of the restraining member, etc., only slightly changes the gap or narrows the gap, there is less concern about peeling, etc., of the sheet-shaped thermally conductive member.

[0063] The battery pack 10D shown in Figure 4A has a low risk of the gap between the cooler 22 and the band body 24 widening when the band body 24 is bent or otherwise damaged, but there is a high risk of the gap between the battery cell 12 and the band body widening.

[0064] In this battery pack 10D, multiple thermally conductive sheets 32 are arranged between the battery cells 12 and the band main body 24. In addition, in the battery pack 10D, a heat transfer sheet 52 is arranged between the cooler 22 and the band main body 24. A graphite sheet or the like is used for the heat transfer sheet 52, and one surface of the heat transfer sheet 52 is joined to the cooler 22 in surface contact, and the other surface is joined to the band main body 24 in surface contact.

[0065] Furthermore, in the battery pack 10E shown in Figure 4B, there is little concern that the gap between the battery cells 12 and the band body 24 will widen when the band body 24 is bent or otherwise damaged, but there is a high concern that the gap between the cooler 22 and the band body will widen.

[0066] In this battery pack 10E, multiple heat conduction sheets 32 are arranged between the cooler 22 and the band main body 24. In addition, in the battery pack 10E, a heat transfer sheet 52 is arranged between the battery cells 12 and the band main body 24, and one surface of the heat transfer sheet 52 is joined in surface contact with the battery cells 12, and the other surface is joined in surface contact with the band main body 24.

[0067] In the assembled batteries 10D and 10E configured in this manner, heat dissipation from the battery cells 12 using the cooler 22 can be maintained, just like in the assembled battery 10, and the same effects as those of the assembled battery 10 can be achieved. Note that in the assembled batteries 10D and 10E, thermally conductive sheets 40 and 42 may be disposed instead of the thermally conductive sheet 32.

[0068] Second Embodiment Next, a second embodiment will be described. The basic configuration of the second embodiment is the same as that of the first embodiment. In the second embodiment, the same functional parts as those in the first embodiment and Modifications 1 to 4 are given the same reference numerals, and the description thereof will be omitted.

[0069] FIG. 5A shows a schematic configuration diagram of a battery pack 60 according to the second embodiment as viewed from the side, and FIG. 5B shows a schematic cross-sectional view of the main parts of the battery pack 60 according to the second embodiment taken along line 5B-5B in FIG. 5A.

[0070] 5A and 5B, the battery pack 60 includes restraint bands 62 as restraint members and a cooler 64 as a cooling member. The restraint bands 62 are disposed in the battery pack 60 in place of the restraint bands 20 of the battery pack 10. The cooler 64 is disposed in the battery pack 60 in place of the cooler 22 of the battery pack 10.

[0071] The restraint band 62 is made of a metal such as iron, which has a high load-bearing capacity, and includes a band-shaped band body 66 and bent portions 68 formed by bending both longitudinal ends of the band body 66.

[0072] The battery pack 60 can use multiple restraint bands 62, and two restraint bands 62 are used in the battery pack 60. The longitudinal direction of the restraint bands 62 is the stacking direction, and the two restraint bands 62 are arranged at a predetermined interval in the middle of the width direction of the battery stack 16 in the battery pack 60.

[0073] The restraint band 62 is positioned so that each of its bent portions 68 abuts against the outer surface of the end plate 14 in the stacking direction, and each bent portion 68 is fastened and fixed to the end plate 14 and attached to the battery stack 16 and assembled to the battery pack 60. The restraint band 62 restrains each of the battery cells 12 in the battery stack 16 by applying an external force between the pair of end plates 14 in a direction that moves them toward each other through each of its bent portions 68.

[0074] The cooler 64 has a plurality of recesses 70 formed on the surface facing the battery stack 16. The recesses 70 are formed in the cooler 64 in a groove-like shape, with the openings extending in the stacking direction when viewed in the stacking direction. The recesses 70 are also formed to match the respective positions of the band body 66, and the band body 66 is housed within the recesses 70.

[0075] The battery pack 60 has a heat conduction section 72 positioned between the battery stack 16 and the cooler 64. The heat conduction section 72 is composed of a heat conduction section 72A between the battery stack 16 and the cooler 64, a heat conduction section 72B between the battery stack 16 and the band body 66, and a heat conduction section 72C between the bottom surface 70A of the recess 70 of the cooler 64 and the band body 66. Multiple heat conduction sheets 32 are arranged in the width direction of the battery stack 16, with their longitudinal direction being the stacking direction, within each of the heat conduction sections 72A, 72B, and 72C.

[0076] In the heat conduction section 72A, one end 36 of the heat conduction sheet 32 ​​is joined to the battery cell 12 by surface contact, and the other end 36 is joined to the cooler 64 by surface contact. In the heat conduction section 72B, one end 36 of the heat conduction sheet 32 ​​is joined to the battery cell 12 by surface contact, and the other end 36 is joined to the band body 66 by surface contact. Furthermore, in the heat conduction section 72C, one end 36 of the heat conduction sheet 32 ​​is joined to the band body 66 by surface contact, and the other end 36 is joined to the cooler 64 (bottom surface 70A of the recess 70) within the recess 70 by surface contact.

[0077] In the battery pack 60 configured in this way, a cooler 64 is positioned opposite the battery stack 16, and each battery cell 12 of the battery stack 16 is restrained by a restraining band 20 placed between the battery stack 16 and the cooler 64. Furthermore, in the battery pack 60, a thermal conductive sheet 32 ​​is placed between the battery cell 12 and the cooler 64, between the battery cell 12 and the band body 66, and between the cooler 64 and the band body 66.

[0078] Therefore, in the battery pack 60, even if the distance between the battery cell 12 and the cooler 64 changes, and the distance between the cooler 64 and the band body 66 in the recess 70 changes, the thermal conductive sheet 32 ​​will elastically deform to follow these changes in distance.

[0079] As a result, even if the band body 66 of the restraining band 62 bends in the battery pack 60, the end 36 of the heat conductive sheet 32 ​​is prevented from peeling off from the battery cell 12, the cooler 64, or the band body 66. Therefore, in the battery pack 60, there is no decrease in the heat conduction efficiency between the battery cell 12 and the cooler 64, and efficient heat suppression of the battery cell 12 using the cooler 64 becomes possible.

[0080] Furthermore, in the battery pack 60, a graphite sheet is used for the thermal conductive sheet 32, making it elastically deformable. As a result, in the battery pack 60, the thermal conductive sheet 32 ​​can be elastically deformed in response to changes in the distance between the ends 36 on both sides, so that not only peeling but also displacement occurs at the ends 36, and effective heat dissipation of the battery cells 12 using the cooler 64 can be maintained. Note that in the battery pack 60, thermal conductive sheets 40 and 42 can be used instead of thermal conductive sheet 32.

[0081] Third Embodiment Next, a third embodiment will be described. The basic configuration of the third embodiment is the same as that of the first embodiment. In the third embodiment, the same functional parts as those in the first embodiment, the second embodiment, and Modifications 1 to 4 are given the same reference numerals, and the description thereof will be omitted.

[0082] Fig. 6A shows a schematic configuration diagram of the main parts of a battery pack 80 according to the second embodiment as seen from the side, and Fig. 6B shows a plan view of the main parts of the battery pack 80 as seen from the battery stack 16 side. Note that Fig. 6B is a plan view of the main parts of a thermally conductive plate 82 described below.

[0083] As shown in FIG. 6A, in the battery pack 80, a pair of end plates 14 are arranged on a battery stack 16 in which multiple battery cells 12 are stacked, and the battery cells 12 are restrained by being pressed against the end plates 14 by the bent portions 26 of the restraint bands 20.

[0084] Additionally, a cooler 22 (not shown) is disposed in the battery pack 80 on the opposite side of the band body 24 from the battery stack 16. In the battery pack 80, a thermally conductive sheet 42 is disposed between the battery stack 16 and the band body 24, and between the cooler 22 and the band body 24, and an end 36 of the thermally conductive sheet 42 is joined in surface contact with the battery cells 12, the cooler 22, or the band body 24. This allows the cooler 22 to dissipate heat from the battery cells 12 in the battery pack 80.

[0085] In the battery pack 80, the longitudinal direction of the thermally conductive sheets 42 is the width direction of the battery stack 16, and multiple thermally conductive sheets 42 are arranged in the stacking direction. In this case, the thermally conductive sheets 42 between the battery stack 16 and the band main body 24 are arranged corresponding to each of the battery cells 12.

[0086] Meanwhile, a heat-conducting plate 82 is arranged in the battery pack 80, and the heat-conducting plate 82 is arranged between the battery stack 16 and the band body 24, on the battery stack 16 (battery cells 12) side and on the band body 24 side. The heat-conducting plate 82 is made of a graphite sheet and is in the shape of an elastically deformable plate. Note that the heat-conducting plate 82 is not limited to being in the shape of a plate, and may also be in the shape of a sheet or film.

[0087] 6B, the heat conduction plate 82 is formed in a band shape and has a plurality of slits 84 arranged along the longitudinal direction. The slits 84 are rectangular and extend in the width direction of the heat conduction plate 82, penetrating the heat conduction plate 82. The heat conduction sheet 42 can be inserted into the slits 84.

[0088] On the battery cell 12 side, the thermally conductive plate 82 is joined in surface contact with the band body 24 side surface of the end 36 of the thermally conductive sheet 42 that is joined to the battery cell 12, and the band body 24 side (curved portion 44 side) of the end 36 of the thermally conductive sheet 42 is pulled out through the slit hole 84. Also, on the band body 24 side, the thermally conductive plate 82 is joined in surface contact with the battery cell 12 side surface of the end 36 of the thermally conductive sheet 32 ​​that is joined to the band body 24, and the battery cell 12 side of the end 36 of the thermally conductive sheet 42 is pulled out through the slit hole 84. In this way, the thermally conductive plate 82 thermally connects the multiple thermally conductive sheets 32 on both the battery cell 12 side and the band body 24 side.

[0089] In the battery pack 80 configured in this manner, multiple thermally conductive sheets 32 are arranged between the battery stack 16 and the band body 24, and between the band body 24 and the cooler 22. As a result, in the battery pack 80, even if the distance between the battery cells 12 and the band body 24, and the distance between the cooler 22 and the band body 24, changes, the thermally conductive sheets 32 can elastically deform in response to this change, thereby achieving the same effects as the battery pack 10.

[0090] Furthermore, in the battery pack 60, a plurality of thermally conductive sheets 32, each in surface contact with a battery cell 12, are joined to the thermally conductive plate 82. This makes it possible to suppress temperature differences between the plurality of battery cells 12 in the battery pack 80, and to equalize the temperatures of the plurality of battery cells 12 arranged in the battery stack 16.

[0091] Furthermore, in the battery pack 80, each of the heat conductive sheets 32 can be pre-bonded and assembled to the heat conductive plate 82, thereby improving the ease of assembling the heat conductive sheets 32 to the battery stack 16. [Explanation of symbols]

[0092] 10, 10A~10E, 60, 80 assembled battery 12 battery cells 14 End plate 16 Battery stack (laminate) 20, 62 Restraint band 22, 64 Cooler (cooling element) 24, 66 band body 26, 68 Bending section 30 (30A, 30B), 50 (50A, 50B), 72 (72A~72C) Heat conduction section 32, 40, 42 Thermally conductive sheet (thermally conductive material) 34, 44 curved section 36 End 82 Heat conduction plate

Claims

1. a stacked body in which a plurality of battery cells are stacked in a stacking direction; a cooling member disposed opposite at least one of the surfaces of the stack in a direction intersecting the stacking direction, for cooling each of the battery cells on the one surface side; a band-shaped restraining member disposed between the stack and the cooling member, the restraining member pressuring the stack at both ends in the stacking direction to restrain each of the battery cells; a heat conduction portion in which a heat conduction member formed in a sheet shape is disposed between the battery cell and the cooling member, with one side in a planar direction joined to the battery cell side and the other side joined to the cooling member side, and an intermediate portion being curved and deformed, and heat is conducted between the battery cell and the cooling member via the heat conduction member; A battery pack including:

2. the heat conduction section has a plurality of heat conduction members arranged in the stacking direction of the battery cells, The battery pack according to claim 1 , further comprising a heat-conducting plate that thermally connects the plurality of heat-conducting members and enables heat to be conducted between the heat-conducting members.

3. 2. The battery pack according to claim 1, wherein the heat conduction members are disposed between the battery cells and the restraining members, and between the restraining members and the cooling member, and are elastically deformable in accordance with changes in the distance between the battery cells and the restraining members and the distance between the restraining members and the cooling member.

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