Battery stack

Abstract

To provide a battery stack which can achieve uniform binding pressure to an electrode body inside a secondary battery while improving heat dissipation.SOLUTION: A battery stack 10 has a plurality of secondary batteries 20 and a plurality of spacers 40. Each of the secondary batteries 20 has an electrode body 22, an insulation film 24 covering the electrode body 22, and a case 26 for housing the electrode body 22 covered with the insulation film 24. Each of the spacers 40 is disposed between adjacent ones of the secondary batteries 20. Each of the spacers 40 has a plurality of ribs 44 which are pressed against a lateral face 26S of the case 26 of the secondary battery 20. Cooling air flows between adjacent ones of the ribs 44. Between the insulation film 24 and a lateral wall 26A of the case 26, a heat conduction material 50 is interposed only within a range corresponding to a space S formed between the ribs 44 adjacent to each other when viewed in an alignment direction of the secondary batteries 20 and the spacers 40.SELECTED DRAWING: Figure 4

Description

[Technical field]

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

[0002] The following Patent Document 1 discloses technology relating to a secondary battery module (battery stack) in which a cell holder (spacer) is arranged between battery cells (secondary batteries). Briefly, in this prior art, the cell holder is constructed by integrally molding a heat-conductive rubber layer on one or both sides of a metal plate-shaped member, and a number of protrusions (ribs) are formed on the surface of the heat-conductive rubber layer that comes into contact with the battery cells. With this configuration, it is possible to improve the heat dissipation properties of the cell holder. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-10939 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned prior art, the electrode body in the battery cell is subjected to a constraining pressure by the battery cell being subjected to pressing forces from multiple protrusions of the cell holder. However, the above-mentioned prior art has room for improvement in terms of making the constraining pressure on the electrode body in the battery cell uniform.

[0005] In consideration of the above, an object of the present invention is to provide a battery stack that can improve heat dissipation and can uniformly apply confining pressure to electrode assemblies in a secondary battery. [Means for solving the problem]

[0006] A battery stack of a first aspect of the present invention comprises a plurality of secondary batteries, each having an electrode body, an insulating film covering the electrode body, and a case in which the electrode body covered by the insulating film is housed, and a plurality of spacers arranged between adjacent secondary batteries and formed with a plurality of ribs pressed against the side surfaces of the case of the secondary batteries, the battery stack being configured so that cooling air flows between adjacent ribs, and a thermally conductive material is interposed between the insulating film and the side wall of the case only within an area corresponding to the space between adjacent ribs when viewed in the direction in which the secondary batteries and the spacers are arranged.

[0007] A battery stack according to a second aspect of the present invention includes a plurality of secondary batteries each having an electrode body, an insulating film covering the electrode body, and a case in which the electrode body covered by the insulating film is housed, and a plurality of spacers disposed between adjacent secondary batteries and each having a plurality of ribs pressed against a side surface of the case of the secondary battery, and configured so that cooling air flows between adjacent ribs, and at least one of the opposing portions of the insulating film and the side wall of the case has a protrusion that protrudes so as to fill the gap between the main body of the insulating film and the main body of the side wall of the case only within a range corresponding to the space between adjacent ribs as viewed in the direction in which the secondary batteries and the spacers are aligned. The concept of "protruding so as to fill the gap between the main body of the insulating film and the main body of the side wall of the case" includes a case in which the protrusion protrudes so as to fill the gap in the entire area of ​​the gap between the main body of the insulating film and the main body of the side wall of the case, as well as a case in which the protrusion protrudes so as to fill the gap in a partial area of ​​the gap between the main body of the insulating film and the main body of the side wall of the case.

[0008] A battery stack according to a third aspect of the present invention is the battery stack according to the first aspect of the present invention, wherein the thermally conductive material includes an adhesive resin and a thermally conductive filler. Effect of the Invention

[0009] In the battery stack of the first aspect of the present invention, the electrode body is covered with an insulating film and has a plurality of secondary batteries housed in a case, and a spacer is disposed between adjacent secondary batteries. A plurality of ribs are formed on each spacer, and each rib is pressed against a side surface of the case of the secondary battery. In addition, cooling air flows between adjacent ribs. Here, a thermally conductive material is interposed between the insulating film and the side wall of the case only within a range corresponding to the space between adjacent ribs when viewed in the direction in which the secondary battery and the spacer are arranged. Therefore, heat transferred from the electrode body to the thermally conductive material through the insulating film is transferred through the side wall of the case to the space between adjacent ribs, i.e., the space through which the cooling air flows, thereby improving heat dissipation. In addition, the range in which the thermally conductive material is interposed between the insulating film and the side wall of the case is within a range corresponding to the space between adjacent ribs, so that the interposition of the thermally conductive material allows the binding pressure on the electrode body from the rib side to act well on a range other than the range corresponding to the rib. Therefore, it is possible to uniform the binding pressure on the electrode body in the secondary battery.

[0010] In the battery stack according to the second aspect of the present invention, the electrode body is covered with an insulating film and a plurality of secondary batteries are housed in a case, and a spacer is disposed between adjacent secondary batteries. A plurality of ribs are formed on each spacer, and each rib is pressed against a side surface of the case of the secondary battery. Cooling air flows between adjacent ribs. Here, at least one of the opposing portions of the insulating film and the side wall of the case has a protruding portion that protrudes so as to fill the gap between the main body of the insulating film and the main body of the side wall of the case only within a range corresponding to the space between adjacent ribs as viewed in the direction in which the secondary battery and the spacer are arranged. Therefore, when the heat of the electrode body is transferred to the protruding portion via the main body of the insulating film and further transferred from the protruding portion to the main body of the side wall of the case, the heat transferred in this way is transferred to the space between adjacent ribs, i.e., the space through which the cooling air flows, thereby improving the heat dissipation. In addition, the range in which the protrusions are provided between the main body of the insulating film and the main body of the side wall of the case is within the range corresponding to the space between the adjacent ribs, so that the provision of the protrusions allows the constraining pressure on the electrode body from the rib side to be effectively applied to ranges other than the range corresponding to the rib, thereby making it possible to uniform the constraining pressure on the electrode body in the secondary battery.

[0011] In the battery stack of the third aspect of the present invention, the thermally conductive material includes an adhesive resin and a thermally conductive filler, so that the thermally conductive material including the thermally conductive filler can be bonded to one of the insulating film and the side wall of the case by the adhesive force of the adhesive resin. [Brief description of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view showing, in a simplified form, a secondary battery constituting a battery stack according to a first embodiment. [Diagram 2] 2 is a perspective view showing a spacer disposed between secondary batteries in the battery stack according to the first embodiment. FIG. [Diagram 3] 1 is a vertical cross-sectional view showing a portion of a battery stack according to a first embodiment. [Figure 4]FIG. 4 is an enlarged sectional view showing a part a in FIG. 3 in an enlarged and simplified manner. [Diagram 5] FIG. 5 is a vertical cross-sectional view (corresponding to FIG. 4 of the first embodiment) showing a part of a battery stack according to a second embodiment. [Figure 6] FIG. 11 is a vertical cross-sectional view (corresponding to FIG. 4 of the first embodiment) showing a part of a battery stack according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] [First embodiment] A battery stack according to a first embodiment will be described with reference to Figures 1 to 4. The battery stack described below is used, for example, as an on-board power source for an electric vehicle or the like.

[0014] Fig. 1 shows a simplified cross-sectional view of a secondary battery 20 constituting a battery stack 10. The battery stack 10 has a plurality of secondary batteries 20 shown in Fig. 1. Each secondary battery 20 is called a cell. The secondary battery 20 is a lithium ion battery, and has an electrode body 22, an insulating film 24 covering the electrode body 22, a case 26 in which the electrode body 22 covered with the insulating film 24 is housed, and a lid assembly 30 provided on the upper side of the case 26.

[0015] Although detailed illustration is omitted, the electrode body 22 is formed by stacking positive and negative electrode sheets, each of which has a composite layer formed on a portion of the surface of a sheet-like positive and negative electrode collector, sandwiching a separator between them and winding the electrode sheets in a flat shape around a winding axis. The electrode body 22 includes an electrode main body 22A constituting a widthwise intermediate portion, and positive and negative electrode tab groups 22B and 22C provided on both sides in the width direction. The electrode main body 22A is a portion where a collector, a composite layer, and a separator are stacked. A flat surface and a semicircular curved end surface are formed on the outer peripheral surface around the winding axis of the electrode main body 22A. The positive and negative electrode tab groups 22B, 22C have multiple tab portions protruding from the electrode main body portion 22A along the axial direction of the winding axis in the battery thickness direction (direction perpendicular to the paper surface of Figure 1), and have foil collecting portions 22S, 22T in which the protruding tip portions of the multiple tab portions are bundled and stacked.

[0016] The insulating film 24 has, for example, a constant thickness and is formed in a bag shape. The electrode body 22 is housed in the insulating film 24. The case 26 is made of metal (for example, aluminum alloy), and is formed in a rectangular box shape that is open at the top and long in the battery width direction (arrow W direction). Each flat plate-shaped portion of the case 26 has, for example, a constant plate thickness. An electrolyte is injected into the case 26.

[0017] The lid assembly 30 has a lid member 32, positive and negative current collecting terminals 34, 35 for inputting and outputting electric power from the electrode body 22, and external terminals 36, 37 for external connection. The lid member 32 is formed in a rectangular plate shape that is long in the battery width direction. The lid member 32 is attached so as to cover the opening of the case 26. The current collecting terminals 34, 35 are joined to the foil collecting parts 22S, 22T. The external terminals 36, 37 are electrically connected to the current collecting terminals 34, 35 of the corresponding positive and negative electrodes.

[0018] FIG. 2 shows a perspective view of a spacer 40 disposed between adjacent secondary batteries 20. In FIG. 2, the secondary batteries 20 are simplified and shown by two-dot chain lines. The battery stack 10 has a plurality of spacers 40 shown in FIG. 2. The spacer 40 is made of resin and is disposed in a state of being sandwiched between the side surfaces 26S (end surfaces in the thickness direction of the secondary batteries 20) of the cases 26 of the secondary batteries 20. The secondary batteries 20 and the spacers 40 are arranged alternately and sandwiched between end plates 48 (see FIG. 3, only one is shown in FIG. 3) arranged on both sides in the direction in which the secondary batteries 20 and the spacers 40 are arranged. A configuration for sandwiching using such end plates 48 (see FIG. 3) can be applied with a known configuration, so detailed description will be omitted. The battery stack 10 is configured to restrain the plurality of secondary batteries 20 by each spacer 40 and each end plate 48 (see FIG. 3).

[0019] 2, the spacer 40 has a flat base portion 42 and a plurality of ribs 44 formed on one surface 42A of the two surfaces of the base portion 42 that faces the side surface 26S of the case 26 of the secondary battery 20. The plurality of ribs 44 are arranged in a comb-like shape, extend in the width direction on both widthwise sides of the base portion 42, and are bent downward in an arc shape at the widthwise center side of the base portion 42, thereby extending downward.

[0020] 3 shows a longitudinal cross-sectional view (a cross-sectional view taken along the line 3L-3L in FIG. 2) of a portion of the battery stack 10. As shown in FIG. 3, the rib 44 is pressed against the side surface 26S of the case 26 of the secondary battery 20. The rib 44 presses against the side wall 26A of the case 26, deforming the side wall 26A and bringing a portion of the side wall 26A into pressing contact with the insulating film 24.

[0021] The battery stack 10 is configured so that cooling air flows between the adjacent ribs 44. In other words, a structure surrounded by a recess 40X formed by the adjacent ribs 44 and one surface 42A of the spacer 40 and a portion of the side surface 26S of the case 26 facing the recess 40X is utilized as a ventilation passage through which cooling air flows for cooling the secondary battery 20. The cooling air for cooling the secondary battery 20 flows in from the lower side of the widthwise center of the spacer 40 shown in FIG. 2, flows outward in the widthwise direction along the extension direction of the ribs 44, and is discharged to the outside from the end side of the spacer 40 on the outer side in the widthwise direction.

[0022] Fig. 4 shows an enlarged and simplified cross-sectional view of part a in Fig. 3. Note that in Fig. 4, the amount of deformation of side wall 26A of case 26 deformed by the pressing of rib 44 is shown somewhat exaggerated in order to make the configuration easier to understand.

[0023] 4, a thermally conductive material 50 is interposed between the insulating film 24 and the sidewall 26A of the case 26 only within a range corresponding to the space S between adjacent ribs 44 as viewed in the direction in which the secondary battery 20 and the spacer 40 are aligned (the left-right direction in FIG. 4). As an example, the thermally conductive material 50 is provided between the insulating film 24 and the sidewall 26A of the case 26 over substantially the entire area within the range corresponding to the space S between adjacent ribs 44 as viewed in the direction in which the secondary battery 20 and the spacer 40 are aligned.

[0024] As an example, the thermally conductive material 50 is bonded to the outer surface 24A of the insulating film 24. The thermally conductive material 50 includes an adhesive resin and a thermally conductive filler, and is pattern-coated on the outer surface 24A of the insulating film 24. The adhesive resin included in the thermally conductive material 50 may be, for example, a urethane-based resin. The thermally conductive filler included in the thermally conductive material 50 may be, for example, aluminum hydroxide, aluminum oxide, aluminum nitride, boron nitride, or the like.

[0025] Next, the operation and effects of the first embodiment will be described.

[0026] In the first embodiment, heat transferred from the electrode body 22, a part of which is shown in Fig. 4, to the thermally conductive material 50 via the insulating film 24 is transferred via the side wall 26A of the case 26 to the space S between the adjacent ribs 44, that is, the space through which the cooling air flows. By ensuring such a heat dissipation route through the thermally conductive material 50, efficient heat dissipation is possible, and the heat dissipation performance can be improved.

[0027] Furthermore, since the range in which the thermally conductive material 50 is interposed between the insulating film 24 and the side wall 26A of the case 26 is within the range corresponding to the space S between the adjacent ribs 44, the presence of the thermally conductive material 50 allows the binding pressure on the electrode body 22 from the rib 44 side to act satisfactorily on ranges other than the range corresponding to the rib 44. Thus, it is possible to uniform the binding pressure on the electrode body 22 inside the secondary battery 20.

[0028] To further explain the above, in a conventional configuration in which the thermally conductive material 50 is removed from the configuration of the first embodiment, a gap is generated between the insulating film and the side wall of the case in the vicinity of the portion where the thermally conductive material 50 of the present embodiment is interposed. When such a gap is generated, the thermal conductivity from the inner portion to the outer portion of the gap is deteriorated, resulting in poor heat dissipation, and the binding pressure on the electrode body from the rib side cannot be applied well to a range other than the range corresponding to the rib. However, in this embodiment, the thermal conductivity is improved by the interposition of the thermally conductive material 50, thereby improving heat dissipation, and the binding pressure on the electrode body 22 from the rib 44 side can be applied well to a range other than the range corresponding to the rib 44 (reducing bias in the binding pressure).

[0029] In the first embodiment, the thermally conductive material 50 includes an adhesive resin and a thermally conductive filler. Therefore, the adhesive force of the adhesive resin can bond the thermally conductive material 50 including the thermally conductive filler to one of the insulating film 24 and the side wall 26A of the case 26 (the insulating film 24 in this embodiment as an example).

[0030] [Second embodiment] Next, a battery stack according to a second embodiment will be described with reference to FIG. 5. FIG. 5 shows a part of a battery stack 60 according to the second embodiment in a vertical cross-sectional view (corresponding to FIG. 4 of the first embodiment). As shown in FIG. 5, the battery stack 60 according to the second embodiment is different from the battery stack 10 according to the first embodiment (see FIGS. 1 to 4) in that it includes a protruding portion 64C constituting a part of an insulating film 64 instead of the thermally conductive material 50 (see FIG. 4). The other configurations are the same as those of the first embodiment. Hereinafter, the same components as those of the first embodiment are denoted by the same reference numerals and will not be described.

[0031] The insulating film 64 includes a main body 64B, which is a component corresponding to the insulating film 24 of the first embodiment (see FIGS. 1 and 3), and a protruding portion 64C formed protruding from the main body 64B. In FIG. 5, to make the drawing easier to see, a two-dot chain line is shown at the boundary between the main body 64B and the protruding portion 64C. In other words, the protruding portion 64C is a portion that protrudes from the position of the two-dot chain line in FIG. 5 toward the side wall 26A of the case 26 (the right side in FIG. 5).

[0032] The protrusions 64C are formed in the insulating film 64 at the portion facing the side wall 26A of the case 26, protruding only within a range corresponding to the space S between adjacent ribs 44 as viewed in the direction in which the secondary battery 62 and the spacer 40 are arranged (the left-right direction in FIG. 5) so as to fill the gap between the main body 64B of the insulating film 64 and the side wall 26A of the case 26. The formation range of the protrusions 64C is, for example, the same as the arrangement range of the thermally conductive material 50 (see FIG. 4) of the first embodiment.

[0033] The secondary battery 62 of the second embodiment has the same configuration as the secondary battery 20 of the first embodiment (see FIGS. 1, 3, etc.), except that it has a protrusion 64C that constitutes a part of the insulating film 64, instead of the thermally conductive material 50 (see FIG. 4). Also, the side wall 26A of the case 26 of the second embodiment has the same configuration as that of the first embodiment, and can be understood as being composed only of a main body portion.

[0034] In the second embodiment, when the heat of the electrode body 22, a part of which is shown in FIG. 5, is transferred to the protruding portion 64C through the main body portion 64B of the insulating film 64, and then transferred from the protruding portion 64C to the side wall 26A of the case 26, the heat transferred in this manner is transferred to the space S between the adjacent ribs 44, that is, the space through which the cooling air flows. This improves the heat dissipation. In addition, the range in which the protruding portion 64C is provided between the main body portion 64B of the insulating film 64 and the side wall 26A of the case 26 is within the range corresponding to the space S between the adjacent ribs 44, and therefore, by providing the protruding portion 64C, the binding pressure on the electrode body 22 from the rib 44 side can be effectively applied to the range other than the range corresponding to the rib 44. This makes it possible to uniformize the binding pressure on the electrode body 22 in the secondary battery 62.

[0035] [Third embodiment] Next, a battery stack according to a third embodiment will be described with reference to FIG. 6. FIG. 6 shows a part of a battery stack 70 according to a third embodiment in a vertical cross-sectional view (corresponding to FIG. 4 of the first embodiment). As shown in FIG. 6, the battery stack 70 according to the third embodiment is different from the battery stack 10 according to the first embodiment (see FIGS. 1 to 4) in that it includes a protruding portion 76C constituting a part of a side wall 76A of a case 76 instead of the thermally conductive material 50 (see FIG. 4). The other configurations are the same as those of the first embodiment. Hereinafter, the same components as those of the first embodiment are denoted by the same reference numerals and will not be described.

[0036] The side wall 76A of the case 76 includes a main body 76B, which is a component corresponding to the side wall 26A of the case 26 of the first embodiment (see FIG. 3 for both), and a protruding portion 76C formed by protruding from a predetermined portion of the main body 76B. In FIG. 6, to make the drawing easier to see, a two-dot chain line is shown at the boundary between the main body 76B and the protruding portion 76C. In other words, the protruding portion 76C is a portion that protrudes toward the insulating film 24 from the position of the two-dot chain line in FIG. 6.

[0037] The protrusions 76C are formed in the portion of the side wall 76A of the case 76 facing the insulating film 24, protruding so as to fill the gap between the insulating film 24 and the main body 76B of the side wall 76A of the case 76 only within a range corresponding to the space S between adjacent ribs 44 when viewed in the direction in which the secondary battery 72 and the spacer 40 are arranged (the left-right direction in FIG. 6). As an example, the protrusions 76C are provided in a region of the separation region between the insulating film 24 and the main body 76B of the side wall 76A of the case 76 excluding the upper and lower end sides.

[0038] In the third embodiment, in order to clearly show the protruding state of the protruding portion 76C, a configuration is exemplified in which the protruding portion 76C is provided in the region excluding the upper end side and the lower end side of the separation region between the insulating film 24 and the main body portion 76B of the side wall 76A of the case 76, but as a modified example, the protruding portion may be provided in the entirety of the separation region. To explain further, anything that protrudes from the main body portion 76B to the insulating film 24 side in the separation region can be understood as a protruding portion.

[0039] The case 76 has the same configuration as the case 26 of the first embodiment (see FIGS. 1 and 3) except that it has a protruding portion 76C. The reference symbol 76S in the figures indicates a side surface of the case 76. The secondary battery 72 has the same configuration as the secondary battery 20 of the first embodiment (see FIGS. 1, 3, etc.) except that it has a protruding portion 76C that constitutes part of the side wall 76A of the case 76 instead of the thermally conductive material 50 (see FIG. 4). The insulating film 24 of the third embodiment has the same configuration as the first embodiment, and can be understood as being composed only of a main body portion.

[0040] In the third embodiment, when the heat of the electrode body 22, a part of which is shown in FIG. 6, is transferred to the protrusion 76C through the insulating film 24, and then transferred from the protrusion 76C to the main body 76B of the side wall 76A of the case 76, the heat transferred in this manner is transferred to the space S between the adjacent ribs 44, that is, the space through which the cooling air flows. This improves the heat dissipation. In addition, the range in which the protrusion 76C is provided between the insulating film 24 and the main body 76B of the side wall 76A of the case 76 is within the range corresponding to the space S between the adjacent ribs 44, and therefore, by providing the protrusion 76C, the binding pressure on the electrode body 22 from the rib 44 side can be effectively applied to the range other than the range corresponding to the rib 44. This makes it possible to uniformize the binding pressure on the electrode body 22 in the secondary battery 72.

[0041] [Modifications of the second and third embodiments] Although not shown in the figures, as a modified example of the second and third embodiments, a configuration can also be adopted in which, on both opposing portions of the insulating film and the side wall of the case, protruding convex portions are formed so as to fill the gap between the main body portion of the insulating film and the main body portion of the side wall of the case only within an area corresponding to the space between adjacent ribs when viewed in the direction in which the secondary battery and spacer are aligned.

[0042] [Supplementary explanation of the embodiment] In the first to third embodiments shown in Figures 1 to 6, as an example, the ribs 44 have the configuration shown in Figure 2. However, the ribs formed on the spacer may have a configuration other than that shown in Figure 2, such as ribs extending linearly in the width direction of the spacer and aligned in the vertical direction.

[0043] As a modification of the first embodiment shown in FIGS. 1 to 4, the heat conductive material (50) may be pattern-coated (bonded) onto the inner surface of the side wall 26A of the case 26.

[0044] In addition, in the above first embodiment, the thermally conductive material 50 includes an adhesive resin and a thermally conductive filler, but the thermally conductive material does not have to include an adhesive resin and a thermally conductive filler as long as it has a higher thermal conductivity than air and can be interposed between the insulating film and the side wall of the case.

[0045] As a modification of the first embodiment, the thermally conductive material may be provided in a predetermined portion, but not substantially the entire area, between the insulating film (24) and the side wall (26A) of the case (26) within a range corresponding to the space (S) between adjacent ribs (44) when viewed in the direction in which the secondary battery (20) and the spacer (40) are aligned.

[0046] Similarly, as a modified example of the second and third embodiments shown in Figures 5 and 6, a configuration may be adopted in which the convex portion is provided in a range different from that of the second and third embodiments between the insulating film (24) and the side wall (26A) of the case (26) within a range corresponding to the space (S) between adjacent ribs (44) when viewed in the direction in which the secondary battery (20) and the spacer (40) are aligned.

[0047] While one example of the present invention has been described above, the present invention is not limited to the above, and it goes without saying that the present invention can be implemented in various modified forms without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0048] 10 Battery stack 20 Secondary battery 22 Electrode body 24 Insulating film 26 cases 26A Case side wall 26S Case Side 40 Spacer 44 Ribs 50 Thermal Conductive Materials 60 Battery Stack 62 Secondary battery 64 Insulating film 64B Insulating film body 64C Convex 70 Battery Stack 72 Secondary battery 76 cases 76A Case Side Wall 76B Case side wall body 76C Convex 76S Case Side S Space between adjacent ribs

Claims

1. A plurality of secondary batteries each having an electrode body, an insulating film covering the electrode body, and a case in which the electrode body covered with the insulating film is housed; a plurality of spacers each having a plurality of ribs formed thereon and pressed against a side surface of the case of the secondary battery, the spacers being disposed between adjacent ones of the secondary batteries; A battery stack having a structure in which cooling air flows between adjacent ribs, A battery stack in which a thermally conductive material is interposed between the insulating film and the side wall of the case only within an area corresponding to the space between adjacent ribs when viewed in the direction in which the secondary battery and the spacer are arranged.

2. A plurality of secondary batteries each having an electrode body, an insulating film covering the electrode body, and a case in which the electrode body covered with the insulating film is housed; a plurality of spacers each having a plurality of ribs formed thereon and pressed against a side surface of the case of the secondary battery, the spacers being disposed between adjacent ones of the secondary batteries; A battery stack having a structure in which cooling air flows between adjacent ribs, A battery stack in which a protruding portion is formed on at least one of the opposing portions of the insulating film and the side wall of the case so as to fill the gap between the main body portion of the insulating film and the main body portion of the side wall of the case only within an area corresponding to the space between adjacent ribs when viewed in the direction in which the secondary battery and the spacer are aligned.

3. The battery stack according to claim 1 , wherein the thermally conductive material comprises an adhesive resin and a thermally conductive filler.

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