Battery pack

Abstract

To provide a battery pack including a spacer whose elastic function does not easily decrease.SOLUTION: A battery pack disclosed herein includes: a plurality of rectangular secondary batteries that are disposed along a predetermined arrangement direction X; and a spacer 200 that is disposed between the rectangular secondary batteries that are adjacent in the arrangement direction X. The spacer 200 includes: an elastic part 210 including a plurality of hollow parts extending along the arrangement direction X and configured to be elastically deformable in the arrangement direction X; and a heat insulation part 220 disposed between the elastic part 210 and the rectangular secondary battery in the arrangement direction X and having lower heat conductivity than the elastic part 210.SELECTED DRAWING: Figure 4

Description

Technical Field

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

Background Art

[0002] Conventionally, in power sources for vehicle drive and the like, a battery pack formed by electrically connecting a plurality of secondary batteries (single cells) has been widely used to increase the output. As related prior art documents, Patent Documents 1 and 2 can be cited.

[0003] For example, Patent Document 1 discloses a battery pack including a plurality of secondary batteries arranged along a predetermined arrangement direction, and a spacer in which through holes extending along a direction orthogonal to the arrangement direction are dispersedly arranged substantially evenly over the entire cross section between adjacent secondary batteries in the arrangement direction. Patent Document 1 describes that the through holes extending along the direction orthogonal to the arrangement direction constitute a flow path for a cooling medium such as cooling air or cooling water, and thus heat dissipation of the secondary batteries is promoted, and that by dispersedly arranging the through holes inside the spacer, elasticity is imparted to the spacer.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] According to the studies of the present inventors, the spacer configured to be elastically deformable may have a reduced elastic function due to long-term use. That is, in recent years, secondary batteries mounted on vehicles and the like have been increasingly made with higher capacities. The secondary battery with increased capacity is likely to generate heat during charge and discharge (especially high-rate charge and discharge). When the secondary battery generates heat, the heat is also transmitted to the spacer in contact with the secondary battery. In particular, when the portion in contact with the secondary battery is made of a material with a high thermal conductivity such as metal, this tendency becomes prominent. As a result, the spacer is prone to thermal degradation and the elastic function is likely to decrease. As a result, there is a risk that the load necessary for maintaining the performance of the secondary battery cannot be applied.

[0006] The present invention has been made in view of the above circumstances, and its main object is to provide a battery pack including a spacer that is less likely to have a reduced elastic function and can stably apply a load to a secondary battery.

Means for Solving the Problems

[0007] The present invention discloses a battery pack including a plurality of rectangular secondary batteries arranged along a predetermined arrangement direction, and a spacer arranged between the adjacent rectangular secondary batteries in the arrangement direction. The spacer has a plurality of hollow portions extending along the arrangement direction, an elastic portion configured to be elastically deformable in the arrangement direction, and a heat insulating portion arranged between the elastic portion and the rectangular secondary battery in the arrangement direction and having a lower thermal conductivity than the elastic portion.

[0008] In the present invention, since the spacer includes an elastic portion having a plurality of hollow portions extending along the array direction and is configured to be elastically deformable in the array direction, even when the secondary battery expands and contracts during charging and discharging, a load can be stably applied to the secondary battery. Further, in the elastic portion, since the plurality of hollow portions extend along the array direction, the structure can be relatively stably maintained as compared with the case where the hollow portions extend perpendicular to the array direction as described in, for example, Patent Document 1. Furthermore, in the present invention, the spacer includes a heat insulating portion in addition to the elastic portion having a plurality of hollow portions. Therefore, due to the heat insulating effect of the hollow portion or the heat insulating portion, the elastic portion is relatively less affected by the heat generation of the secondary battery and is less likely to be thermally deteriorated as compared with the case where the spacer does not have the hollow portion or the heat insulating portion as described above. With the combined effects as described above, in the present invention, a decrease in the elastic function of the elastic portion can be suppressed, and thus a load can be stably applied to the secondary battery.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0010] Hereinafter, some preferred embodiments of the assembled battery disclosed herein will be described with reference to the drawings as appropriate. Matters other than those specifically mentioned in this specification and necessary for the implementation of the present invention (for example, the general configuration and manufacturing process of an assembled battery or a prismatic secondary battery that does not characterize the present invention) can be grasped as design matters of those skilled in the art based on the prior art in the relevant field. The assembled battery disclosed herein can be implemented based on the content disclosed in this specification and the common general knowledge in the relevant field.

[0011] In the following drawings, members and parts having the same function are denoted by the same reference numerals, and duplicate explanations may be omitted or simplified. Also, the notation "A to B" indicating a range in this specification includes the meaning of "not less than A and not more than B", as well as the meaning of "preferably greater than A" and "preferably less than B".

[0012] FIG. 1 is a perspective view schematically showing an assembled battery 500 according to an embodiment. The assembled battery 500 includes a plurality of prismatic secondary batteries 100 arranged along the arrangement direction X, and a plurality of spacers 200 arranged between adjacent prismatic secondary batteries 100 in the arrangement direction X. The assembled battery 500 further includes a restraint mechanism 300 here. In the following description, the reference signs L, R, F, Rr, U, D in the drawings represent left, right, front, rear, upper, and lower, respectively, and the reference signs X, Y, Z in the drawings represent the thickness direction, the long side direction orthogonal to the thickness direction, and the vertical direction orthogonal to the thickness direction and the long side direction of the prismatic secondary battery 100, respectively. The thickness direction X is also the arrangement direction of the prismatic secondary batteries 100. However, these are merely directions for convenience of explanation and do not limit the installation form of the assembled battery 500 in any way.

[0013] The restraint mechanism 300 is configured to apply a specified restraint pressure to a plurality of rectangular secondary batteries 100 and a plurality of spacers 200 in the arrangement direction X. Here, the restraint mechanism 300 is composed of a pair of end plates 310, a pair of side plates 320, and a plurality of screws 330. The pair of end plates 310 are arranged at both ends of the plurality of rectangular secondary batteries 100 in the arrangement direction X. The pair of end plates 310 sandwich the plurality of rectangular secondary batteries 100 and the plurality of spacers 200 in the arrangement direction X. The pair of end plates 310 are preferably made of metal. However, a part thereof may be made of resin.

[0014] The pair of side plates 320 bridge the pair of end plates 310. The pair of side plates 320 are preferably made of metal. However, a part thereof may be made of resin. The pair of side plates 320 are fixed to the end plates 310 by a plurality of screws 330 so that the restraint load is approximately 10 to 15 kN, for example. Thereby, a restraint load is applied to the plurality of rectangular secondary batteries 100 and the plurality of spacers 200 from the arrangement direction X, and the assembled battery 500 is integrally held. However, the configuration of the restraint mechanism is not limited to this. The restraint mechanism 300 may include a plurality of restraint bands, binding bars, etc. instead of the side plates 320, for example.

[0015] The plurality of rectangular secondary batteries 100 are arranged side by side between the pair of end plates 310 along the arrangement direction X (in other words, the thickness direction X of the rectangular secondary battery 100). The plurality of rectangular secondary batteries 100 are preferably restrained by the restraint mechanism 300. Although not shown in FIG. 1, when the assembled battery 500 is used, the plurality of rectangular secondary batteries 100 are electrically connected by a conductive member such as a bus bar. The connection method is not particularly limited, and may be, for example, series, parallel, or multi-series multi-parallel.

[0016] The rectangular secondary battery 100 is a battery capable of repeated charge and discharge. In this specification, the term "secondary battery" refers to all rechargeable power storage devices. In addition to so-called storage batteries such as lithium-ion secondary batteries and nickel-metal hydride batteries, it includes capacitors such as lithium-ion capacitors and electric double-layer capacitors. Further, the shape, size, number, arrangement, etc. of the rectangular secondary batteries 100 constituting the battery pack 500 are not limited to the embodiments disclosed herein and can be appropriately changed.

[0017] FIG. 2 is a perspective view of the rectangular secondary battery 100. FIG. 3 is a schematic longitudinal sectional view taken along line III-III of FIG. 2. As shown in FIG. 3, the rectangular secondary battery 100 includes a battery case 10, an electrode body 20, a positive electrode terminal 30, a negative electrode terminal 40, a positive electrode current collector member 50, a negative electrode current collector member 60, and a non-aqueous electrolyte (not shown). The non-aqueous electrolyte may be the same as that used conventionally and is not particularly limited. The rectangular secondary battery 100 is a lithium-ion secondary battery here.

[0018] The battery case 10 is a housing that houses the electrode body 20 and the non-aqueous electrolyte. As shown in FIG. 2, the battery case 10 has an outer shape of a flat and bottomed rectangular parallelepiped (rectangular). The material of the battery case 10 may be the same as that conventionally used and is not particularly limited. The battery case 10 is preferably made of metal, and more preferably made of, for example, aluminum, aluminum alloy, iron, iron alloy, etc. The battery case 10 includes an outer package 12 and a sealing plate (lid) 14. The battery case 10 preferably includes the outer package 12 and the sealing plate 14 as in this embodiment.

[0019] As shown in FIG. 2, the outer package 12 includes a substantially rectangular bottom wall 12a, a pair of long side walls 12b extending from the long sides of the bottom wall 12a and facing each other, a pair of short side walls 12c extending from the short sides of the bottom wall 12a and facing each other, and an opening 12h (see FIG. 3) facing the bottom wall 12a. The long side wall 12b is a surface facing the spacer 200. The area of the long side wall 12b is larger than the area of the short side wall 12c. The sealing plate 14 is a plate-like member that seals the opening 12h of the outer package 12. As shown in FIG. 3, the sealing plate 14 is attached to the outer package 12 so as to close the opening 12h. The sealing plate 14 faces the bottom wall 12a of the outer package 12. The sealing plate 14 is substantially rectangular. The battery case 10 is integrated by joining (preferably, welding) the sealing plate 14 to the periphery of the opening 12h of the outer package 12. The battery case 10 is hermetically sealed.

[0020] In this specification, the term "substantially rectangular" includes, in addition to a perfect rectangular shape (rectangular shape), for example, a shape in which the corners connecting the long side and the short side of the rectangular shape are R-shaped, a shape having a notch at the corner, and the like.

[0021] As shown in FIG. 3, the sealing plate 14 is provided with a liquid injection hole 15, a discharge valve 17, and two terminal lead-out holes 18 and 19. It is preferable to provide the liquid injection hole 15 and the discharge valve 17 in the sealing plate 14. The liquid injection hole 15 is for injecting a non-aqueous electrolyte after the sealing plate 14 is assembled to the outer package 12. The liquid injection hole 15 is sealed by a sealing member 16. The discharge valve 17 is configured to break when the pressure in the battery case 10 reaches a predetermined value or more and discharge the gas in the battery case 10 to the outside. The terminal lead-out holes 18 and 19 penetrate the sealing plate 14 in the vertical direction Z. The terminal lead-out holes 18 and 19 each have an inner diameter large enough to allow the positive electrode terminal 30 and the negative electrode terminal 40 before being attached to the sealing plate 14 (before caulking) to pass through.

[0022] The positive electrode terminal 30 is disposed at one end (the left end in FIGS. 2 and 3) in the long side direction Y of the sealing plate 14. The negative electrode terminal 40 is disposed at the other end (the right end in FIGS. 2 and 3) in the long side direction Y of the sealing plate 14. The positive electrode terminal 30 and the negative electrode terminal 40 are preferably attached to the sealing plate 14. As shown in FIG. 3, the positive electrode terminal 30 and the negative electrode terminal 40 extend from the inside to the outside of the sealing plate 14 through the terminal lead-out holes 18 and 19. Here, the positive electrode terminal 30 and the negative electrode terminal 40 are caulked to the peripheral portion surrounding the terminal lead-out holes 18 and 19 of the sealing plate 14 by caulking. Caulking portions 30c and 40c are formed at the ends on the side of the exterior bodies 12 of the positive electrode terminal 30 and the negative electrode terminal 40 (the lower ends in FIG. 3).

[0023] As shown in FIG. 3, inside the exterior body 12, the positive electrode terminal 30 is electrically connected to the positive electrode current collecting portion 23 of the electrode body 20 via the positive electrode current collecting member 50. Inside the exterior body 12, the negative electrode terminal 40 is electrically connected to the negative electrode current collecting portion 25 of the electrode body 20 via the negative electrode current collecting member 60. The positive electrode terminal 30 is insulated from the sealing plate 14 by the internal insulating member 80 and the gasket 90. The negative electrode terminal 40 is insulated from the sealing plate 14 by the internal insulating member 80 and the gasket 90.

[0024] As shown in FIGS. 2 and 3, plate-shaped positive electrode external conductive members 32 and negative electrode external conductive members 42 are attached to the outer surface of the sealing plate 14. The positive electrode external conductive member 32 is electrically connected to the positive electrode terminal 30. The negative electrode external conductive member 42 is electrically connected to the negative electrode terminal 40. The positive electrode external conductive member 32 and the negative electrode external conductive member 42 are members to which conductive members such as bus bars for electrically connecting a plurality of rectangular secondary batteries 100 to each other are attached. The positive electrode external conductive member 32 and the negative electrode external conductive member 42 are insulated from the sealing plate 14 by the external insulating member 92. The assembled battery 500 is, for example, serially connected by electrically connecting the positive electrode external conductive member 32 of one rectangular secondary battery 100 and the negative electrode external conductive member 42 of the other rectangular secondary battery 100 adjacent to each other with a bus bar or the like.

[0025] The electrode body 20 has a positive electrode and a negative electrode. The configuration of the electrode body 20 may be the same as the conventional one and is not particularly limited. Also, the number of electrode bodies 20 arranged inside one exterior body 12 is not particularly limited and may be plural. Here, the electrode body 20 is a flat wound electrode body formed by laminating a strip-shaped positive electrode and a strip-shaped negative electrode in an insulated state and winding them around a winding axis. However, in other embodiments, the electrode body 20 may be a stacked electrode body formed by stacking a plurality of rectangular positive electrodes and a plurality of rectangular negative electrodes in an insulated state.

[0026] As shown in FIG. 3, a positive electrode current collector 23 is provided at one end of the electrode body 20 in the winding axis direction (the long side direction Y in FIG. 3). A negative electrode current collector 25 is provided at the other end. A positive electrode current collector member 50 is attached to the positive electrode current collector 23. A negative electrode current collector member 60 is attached to the negative electrode current collector 25. The positive electrode current collector member 50 constitutes a conduction path that electrically connects the positive electrode terminal 30 and the positive electrode of the electrode body 20. The negative electrode current collector member 60 constitutes a conduction path that electrically connects the negative electrode terminal 40 and the negative electrode of the electrode body 20.

[0027] Here, the spacers 200 are respectively arranged between a plurality of rectangular secondary batteries 100 in the arrangement direction X. That is, in the arrangement direction X, the rectangular secondary batteries 100 and the spacers 200 are arranged alternately. However, the spacers 200 only need to be arranged between at least two adjacent rectangular secondary batteries 100 in the arrangement direction X and do not necessarily need to be arranged between all the rectangular secondary batteries 100. Here, a pair of surfaces (both surfaces in the arrangement direction X) of the spacer 200 that are orthogonal to the arrangement direction X are respectively in contact (direct contact) with the long side walls 12b of the rectangular secondary battery 100. However, other members may be interposed between the rectangular secondary battery 100 and the spacer 200.

[0028] FIG. 4 is a perspective view schematically showing the spacer 200. As shown in FIG. 4, the spacer 200 includes an elastic part 210 and a heat insulating part 220. The elastic part 210 and the heat insulating part 220 in FIG. 4 each have a flat outer shape. The elastic part 210 and the heat insulating part 220 are laminated in the arrangement direction X. Here, the spacer 200 has a two-layer structure of one elastic part 210 and one heat insulating part 220. The elastic part 210, here, of a pair of surfaces orthogonal to the thickness direction X (Y-Z plane in FIG. 4), one faces (here, abuts) the heat insulating part 220, and the other faces (here, abuts) the long side wall 12b of the battery case 10. The heat insulating part 220, here, of a pair of surfaces orthogonal to the thickness direction X (Y-Z plane in FIG. 4), one faces (here, abuts) the elastic part 210, and the other faces (here, abuts) the long side wall 12b of the battery case 10.

[0029] The elastic part 210 and the heat insulating part 220 are preferably integrated. In particular, it is preferably integrated by an integrating member. Thereby, the lamination shift between the elastic part 210 and the heat insulating part 220 can be prevented. Also, the productivity and workability of the assembled battery 500 can be improved. In the present specification, "integration" is a term that includes detachable fixing using an integrating member, non-detachable adhesion, etc., and fitting (mechanical joining) and integral molding without using an integrating member. The elastic part 210 and the heat insulating part 220 may be fixed, for example, with a tape or the like as an integrating member, or may be entirely covered and wrapped with a resin sheet, a laminate film, or the like as an integrating member, or may be adhered by chemical or physical force via an adhesive or an adhesive layer (such as a double-sided tape) as an integrating member, or may be processed as a single member by fitting or integral molding without using an integrating member.

[0030] As shown in FIG. 4, the elastic portion 210 and the heat insulating portion 220 here have substantially the same area in the Y-Z plane (processing errors are allowable). The area of the elastic portion 210 and the heat insulating portion 220 in the Y-Z plane is preferably 50% or more, more preferably 70% or more, and particularly preferably 80% or more of the area of the long side wall 12b (the surface facing the spacer 200) of the battery case 10. Thereby, the effects of the technology disclosed herein can be exerted at a high level.

[0031] As shown in FIG. 4, the thickness t1 of the elastic portion 210 is preferably 5% or more, for example, 5 to 15% of the thickness (the length in the thickness direction X) of the prismatic secondary battery 100 in the state before being assembled and compressed into the assembled battery 500. The thickness t2 of the heat insulating portion 220 is preferably 2% or more, for example, 2 to 20% of the thickness (the length in the thickness direction X) of the prismatic secondary battery 100 in the state before being assembled and compressed into the assembled battery 500, and more preferably 5% or more, for example, 5 to 15%. The total of the thickness t1 and the thickness t2 is preferably 7% or more, for example, 7 to 35%, and more preferably 10% or more, for example, 10 to 30% of the thickness (the length in the thickness direction X) of the prismatic secondary battery 100.

[0032] However, the shape, size, arrangement, etc. of the elastic portion 210 and the heat insulating portion 220 can be appropriately determined according to, for example, the shape, size, capacity (degree of expansion and contraction), etc. of the prismatic secondary battery 100. For example, the spacer 200 may have a structure of three or more layers. The spacer 200 may have, for example, a three-layer structure (heat insulating portion 220 / elastic portion 210 / heat insulating portion 220) in which the heat insulating portions 220 are respectively arranged on both side surfaces of the elastic portion 210 in the arrangement direction X, or conversely, in the arrangement direction X, it may have a three-layer structure (elastic portion 210 / heat insulating portion 220 / elastic portion 210) in which the elastic portions 210 are respectively arranged on both side surfaces of the heat insulating portion 220. Alternatively, it may have a structure of four or more layers, or may include portions other than the elastic portion 210 and the heat insulating portion 220.

[0033] The elastic part 210 is configured to be elastically deformable in the array direction X. Therefore, when the rectangular secondary battery 100 expands during charging or the like and the load applied to the elastic part 210 increases, the elastic part 210 is compressed. On the other hand, when the rectangular secondary battery 100 contracts during discharging or the like and the load applied to the elastic part 210 decreases, the elastic part 210 returns to its original shape again. Thus, by providing the elastic part 210 in the spacer 200, even when the rectangular secondary battery 100 expands and contracts during charge and discharge, the rectangular secondary battery 100 can be stably pressed with a predetermined restraint load, and the load necessary for maintaining performance can be stably applied. Also, when charge and discharge are repeated, the rectangular secondary battery 100 may expand. In such a case, the expansion can be absorbed, and it is possible to suppress the application of an excessive restraint load exceeding a predetermined value to the rectangular secondary battery 100 or the opening of the inter-pole distance between the positive and negative electrodes and the deterioration of performance.

[0034] The elastic modulus of the elastic part 210 is preferably 10 MPa or less, more preferably 5 MPa or less, and even more preferably 3.5 MPa or less. By setting the elastic modulus of the elastic part 210 to a predetermined value or less, the spacer 200 is likely to be crushed when the rectangular secondary battery 100 is charged or when the rectangular secondary battery 100 expands. The elastic modulus of the elastic part 210 is preferably 1 MPa or more, more preferably 1.5 MPa or more, and even more preferably 3.0 MPa or more. By setting the elastic modulus of the elastic part 210 to a predetermined value or more, the spacer 200 is likely to return to its shape when the rectangular secondary battery 100 is discharged. Also, when the rectangular secondary battery 100 expands, it repels and it becomes easier to suppress the expansion. Note that the elastic modulus of the elastic part 210 can be adjusted, for example, by the materials, structures, etc. described later.

[0035] In this specification, the "elastic modulus" refers to the value obtained as follows. First, a test piece with a pair of surfaces orthogonal to the thickness direction X each having a square shape of 5 cm × 5 cm is prepared, and the initial thickness (mm) is measured with a micrometer. Next, using a conventionally known compression test apparatus, under the condition of a compression speed of 30 N / min (12 kPa / min), the test piece is compressed at a constant speed in the thickness direction X until the compression load per unit area of the test piece reaches 3.9 MPa, and the compression load (MPa) and the thickness after compression (mm) are measured. Next, with the compression rate (%) obtained from (initial thickness - thickness after compression) (mm) / initial thickness (mm) × 100 from the compression load (MPa) and the thickness after compression (mm) on the horizontal axis and the compression load (N / mm 2 = MPa) on the vertical axis, a compression load-compression rate curve (FS curve) is created. FIG. 5 is a schematic FS curve. Then, as shown in FIG. 5, the slope of the approximate straight line A in the range of 1 to 20% of the compression rate of the FS curve (horizontal axis: compression rate, vertical axis: compression load) is defined as the elastic modulus (MPa). The smaller the value of the elastic modulus, the softer it is, indicating that it is more likely to elastically deform in the thickness direction X.

[0036] It is more preferable that when the elastic portion 210 is allowed to stand for 2 hours after the above compression test and the thickness is measured with a micrometer, the thickness after standing for 2 hours is within -20% of the initial thickness. Thereby, when the prismatic secondary battery 100 repeatedly contracts and expands with the charge and discharge cycles, it becomes easier to return the shape of the elastic portion 210.

[0037] Considering the above range of the elastic modulus, the elastic portion 210 is preferably made of a polymer material. Examples of the polymer material include rubbers (thermosetting elastomers) such as silicone rubber, fluororubber, urethane rubber, natural rubber, styrene-butadiene rubber, butyl rubber, ethylene-propylene rubber (EPM, EPDM), butadiene rubber, isoprene rubber, and norbornene rubber. Among them, EPDM and silicone rubber are preferred. The elastic portion 210 is preferably made of rubber.

[0038] FIG. 6 is a plan view of a plane (Y-Z plane) orthogonal to the thickness direction X (arrangement direction X) of the elastic portion 210. As shown in FIG. 6, in the present embodiment, the elastic portion 210 has a hole structure. The elastic portion 210 includes a plurality of hollow portions 212 extending along the thickness direction X (arrangement direction X) and partition walls (ribs) 214 partitioning the plurality of hollow portions 212. By including the hollow portions 212 in the elastic portion 210, it becomes easier to elastically deform in the arrangement direction X. Further, since the plurality of hollow portions 212 extend along the thickness direction X (arrangement direction X), for example, compared to the case where the plurality of hollow portions 212 extend perpendicular to the arrangement direction X, the structure can be relatively stably maintained, and a decrease in the elastic function can be suppressed. Furthermore, due to the heat insulation effect of the hollow portions 212, even when the prismatic secondary battery 100 generates heat during charging and discharging, etc., the elastic portion 210 is less likely to be affected by the heat generation. Therefore, thermal degradation of the elastic portion 210 can be suppressed. In addition, compared to, for example, the aspect disclosed in Patent Document 2, the spacer 200 can be made relatively thin, and the volume energy density of the assembled battery 500 can be improved.

[0039] The partition walls 214 constitute the framework of the elastic portion 210. As shown in FIG. 6, the partition walls 214 are regularly provided on a plane (Y-Z plane) orthogonal to the thickness direction X (arrangement direction X). The partition walls 214 extend along the thickness direction X (from the front side to the back side in FIG. 6). The partition walls 214 partition the plurality of hollow portions 212.

[0040] The plurality of hollow portions 212 are partitioned by the partition walls 214 and are regularly arranged along the thickness direction X (arrangement direction X). The plurality of hollow portions 212 are independent of each other here. These points are different from a porous (sponge-like) shape having voids communicating in a three-dimensional network form. Although not particularly limited, the size (volume) of one hollow portion 212 is 1 mm 3The above is preferable. The shape of the hollow portion 212 in the Y-Z plane view is hexagonal here. That is, the hollow portion 212 has a hexagonal prism shape along the thickness direction X. Here, both ends of the hollow portion 212 in the thickness direction X (array direction X) are open. The hollow portion 212 is a through-hole here. The elastic portion 210 has a through-hole structure, specifically a polygonal prism through-hole structure (more specifically, a hexagonal prism through-hole structure). Note that in this specification, the "hole structure" refers to a structure in general having a plurality of hollow portions 212 regularly arranged along the thickness direction X (array direction X).

[0041] As shown in FIG. 6, the elastic portion 210 has a honeycomb structure here. Thereby, it becomes easier to maintain the hollow portion 212 even when the charge-discharge cycle is repeated, and it becomes easier to stably exhibit the elastic function over a long period. Note that in this specification, the "honeycomb structure" is a structure included in the "hole structure", and is not limited to the case where the shape of the hollow portion 212 in the Y-Z plane view is hexagonal, and refers to the entire three-dimensional space filling in which solid figures are arranged without gaps.

[0042] As shown in FIG. 6, in the plane (Y-Z plane) orthogonal to the thickness direction X (array direction X), the ratio of the total area of the plurality of hollow portions 212 to the total area of the elastic portion 210 is preferably 0.25 or more, and more preferably 0.35 to 0.8. By setting the above ratio to a predetermined value or more, it becomes easier to absorb the expansion of the rectangular secondary battery 100, and the rectangular secondary battery 100 can be stably pressed with a restraint load equal to or more than a predetermined value. Also, when the rectangular secondary battery 100 expands, it becomes easier to collapse and absorb the expansion. By setting the above ratio to a predetermined value or less, the hollow portion 212 can be stably maintained, and the durability of the elastic portion 210 can be improved.

[0043] The heat insulation part 220 is disposed between the elastic part 210 and the rectangular secondary battery 100 in the arrangement direction X. The heat insulation part 220 is a part having a lower thermal conductivity than the elastic part 210. In other words, the heat insulation part 220 is a part having higher heat insulation than the elastic part 210. By providing the heat insulation part 220, even if the rectangular secondary battery 100 generates heat during charging and discharging or the like, due to the heat insulation effect of the heat insulation part 220, the elastic part 210 is less likely to be affected by the heat generation. Therefore, thermal degradation of the elastic part 210 can be suppressed. Further, even if the temperature of the rectangular secondary battery 100 rises, transmission of the heat to the adjacent rectangular secondary battery 100 can be suppressed. Accordingly, chain heat generation of the rectangular secondary batteries 100 can be suppressed, and it is possible to prevent the entire assembled battery 500 from becoming excessively high temperature.

[0044] From such a viewpoint, the thermal conductivity of the heat insulation part 220 is preferably 0.15 W / (m·K) or less, and more preferably 0.1 W / (m·K) or less. Further, it is more preferable that the heat insulation part 220 is disposed on both surfaces of the elastic part 210 in the arrangement direction X. Thereby, the effects of the technology disclosed herein can be exhibited at a particularly high level. In this specification, the thermal conductivity refers to a value measured based on JIS A1412-1 (2016).

[0045] The heat insulation part 220 may be a porous body. Thereby, air is included in the heat insulation part 220, and a high heat insulation function can be exhibited. The heat insulation part 220 is preferably configured to include, for example, an inorganic filler (such as ceramics such as alumina) and a polymer material. The heat insulation part 220 is preferably configured mainly with an inorganic filler (a component that occupies the largest mass among the constituent components, for example, a component that occupies 50 mass% or more when the total of the constituent components is 100 mass%). The elastic modulus of the heat insulation part 220 is larger than that of the elastic part 210 here. However, the elastic modulus of the heat insulation part 220 may be smaller than that of the elastic part 210, or may be the same as that of the elastic part 210.

[0046] In a preferred embodiment, for example, when the spacer 200 is assembled to and compressed by the battery pack 500, a part of the elastic portion 210 is disposed within the heat insulating portion 220. In one example, the elastic portion 210 has one or more convex portions, the heat insulating portion 220 has concave portions corresponding to such convex portions, and the convex portions of the elastic portion 210 are disposed within the concave portions of the heat insulating portion 220. More specifically, for example, a part of the partition wall 214 of the elastic portion 210 (a portion near the heat insulating portion 220) bites into the heat insulating portion 220. Alternatively, in another example, conversely to the above, the heat insulating portion 220 has one or more convex portions, the elastic portion 210 has concave portions corresponding to such convex portions, and the convex portions of the heat insulating portion 220 are disposed within the concave portions of the elastic portion 210. More specifically, for example, the convex portions of the heat insulating portion 220 pierce into the hollow portion 212 (through hole) of the elastic portion 210. Thereby, the integrality between the elastic portion 210 and the heat insulating portion 220 can be improved, and lamination displacement can be prevented. Further, since the elastic portion 210 and the heat insulating portion 220 partially overlap in the thickness direction X, the spacer 200 can be made thinner, and the volume energy density of the battery pack 500 can be improved.

[0047] The battery pack 500 can be used for various applications, but is particularly suitable for applications that repeatedly perform high-rate charge and discharge (where heat generation is likely to occur during charge and discharge), for example, as a power source (driving power source) for a motor mounted on a vehicle such as a passenger car or a truck. The type of vehicle is not particularly limited, and examples include a plug-in hybrid electric vehicle (PHEV), a hybrid electric vehicle (HEV), and a battery electric vehicle (BEV).

[0048] The preferred embodiments of the present invention have been described above, but the above embodiments are merely examples. The present invention can be implemented in various other forms. The present invention can be implemented based on the content disclosed in this specification and the common general knowledge in the art. The technology described in the claims includes various modifications and changes to the embodiments exemplified above. For example, it is possible to replace some of the above-described embodiments with the following modification examples, and it is also possible to add other modification examples to the above-described embodiments. Further, if its technical features are not described as essential, it can be appropriately deleted.

[0049] (1) For example, in the above-described embodiment, the elastic portion 210 and the heat insulating portion 220 each had a flat plate-like outer shape, and the areas of the surfaces (Y-Z planes) orthogonal to the thickness direction X (arrangement direction X) were substantially the same. However, this is not limiting. The areas of the Y-Z planes of the elastic portion 210 and the heat insulating portion 220 may be different from each other. In a modification example, it is preferable that the area of the Y-Z plane of the elastic portion 210 is less than or equal to the area of the Y-Z plane of the heat insulating portion 220. When the area of the heat insulating portion 220 is large, the influence of the heat generation of the rectangular secondary battery 100 can be further reduced, and the thermal degradation of the elastic portion 210 can be suppressed at a high level.

[0050] (2) For example, in the above-described embodiment, the plurality of hollow portions 212 included in the elastic portion 210 were independent of each other. However, this is not limiting. The plurality of hollow portions 212 may be communicated by holes penetrating the partition wall 214. In other words, the elastic portion 210 may have holes communicating the plurality of hollow portions 212. According to such an aspect, the entry and exit of air in the plurality of hollow portions 212 become smooth, and it is possible to suppress a decrease in the elastic function due to the so-called suction cup effect.

[0051] (3) For example, in the above-described embodiment, the elastic portion 210 has a honeycomb structure, and the plurality of hollow portions 212 included in the elastic portion 210 had a hexagonal shape when viewed in the Y-Z plane. However, it is not limited to this. The hollow portion 212 may not have a honeycomb structure. The hollow portions 212 may be randomly arranged. Also, the shape of the hollow portion 212 when viewed in the Y-Z plane may be a shape other than a hexagonal shape, for example, a circular shape, a triangular shape, a square shape, etc.

[0052] FIG. 7 is a view corresponding to FIG. 6 of the elastic portion 210a according to the first modification. As shown in FIG. 7, in the elastic portion 210a, the plurality of hollow portions 212a are circular. That is, the elastic portion 210a has a circular through-hole structure here. Also, FIG. 8 is a view corresponding to FIG. 6 of the elastic portion 210b according to the second modification. As shown in FIG. 8, in the elastic portion 210b, the plurality of hollow portions 212b are square. That is, the elastic portion 210a has a regular mesh (lattice) structure here. However, a random mesh (lattice) structure may also be used.

[0053] (4) For example, in the above-described embodiment, the hollow portion 212 of the elastic portion 210 was a through-hole with both ends in the thickness direction X (arrangement direction X) being open. The elastic portion 210 was a polygonal column through-hole structure (more specifically, a hexagonal column through-hole structure). However, it is not limited to this. In a modification, one or both ends of the hollow portion 212 in the arrangement direction X may be closed. The elastic portion 210 may have a non-through-hole structure. Also, the middle of the space in the thickness direction X (arrangement direction X) of the hollow portion 212 may be partitioned.

[0054] Figs. 9(A) to 9(C) are schematic views of the elastic portion 210c according to the third modification. Fig. 9(A) is a plan view of the rear surface 210Rr (the first Y-Z plane) of the elastic portion 210c, Fig. 9(B) is a plan view of the front surface 210F (the second Y-Z plane) of the elastic portion 210c, and Fig. 9(C) is a longitudinal sectional view (in the thickness direction X) along the line IXC-IXC in Fig. 9(A). As shown in Fig. 9(C), the elastic portion 210c has, in addition to a plurality of hollow portions 212c extending along the thickness direction X (the arrangement direction X) and partition walls 214c partitioning the plurality of hollow portions 212c, a flat base portion 216 that supports the partition walls 214c.

[0055] As shown in Figs. 9(B) and 9(C), the base portion 216 extends along the front surface 210F of the elastic portion 210c. The base portion 216 is a portion that does not have the hollow portions 212c here. The base portion 216 is a non-porous (solid structure) portion. The base portion 216 may be provided on the surface on the side facing the long side wall 12b of the rectangular secondary battery 100, or may be provided on the surface on the side facing the heat insulating portion 220. By having the base portion 216, alignment with the rectangular secondary battery 100 becomes easy, and the productivity and workability of the assembled battery 500 can be improved. From such a viewpoint, it is preferable that the height (the length in the vertical direction Z) and / or the width (the length in the long side direction Y) of the base portion 216 substantially coincide with the height and / or the width of the long side wall 12b of the rectangular secondary battery 100.

[0056] The thickness (the length in the arrangement direction X) of the base portion 216 is preferably 0.1 mm or more, and more preferably 0.3 mm or more. The thickness of the base portion 216 is preferably 5 mm or less, and more preferably 2 mm or less. The thickness (the length in the arrangement direction X) of the base portion 216 may not be uniform in the Y-Z plane, and there may be partially thick or thin portions. Also, the area of the base portion 216 in the Y-Z plane may be equal to or larger than the area in the Y-Z plane where the partition walls 214c are present. The partition walls 214c extend from the base portion 216 along the thickness direction X (the arrangement direction X).

[0057] The hollow portion 212c here has a hexagonal column shape along the thickness direction X. One end of the hollow portion 212c in the thickness direction X (arrangement direction X) (the front end in FIG. 9(C)) is closed. Here, the surface of the hollow portion 212c on the side facing the heat insulation portion 220 is closed by the base portion 216. The elastic portion 210c is comb-shaped in a cross-sectional view in the thickness direction X. By closing one end of the hollow portion 212c in this way, integration with the heat insulation portion 220 becomes easy and workability can be improved. On the other hand, as shown in FIG. 9(A), the other end of the hollow portion 212c (the rear end) in the thickness direction X (arrangement direction X) is open. Here, the surface on the side facing the long side wall 12b of the rectangular secondary battery 100 is open.

[0058] (5) Note that the hollow portion 212 of the above-described embodiment and the hollow portion 212c of the third modification had a hexagonal column shape along the thickness direction X. However, it is not limited to this. FIG. 10 is a view corresponding to FIG. 9(C) of the elastic portion 210d according to the fourth modification. As shown in FIG. 10, the elastic portion 210d includes a plurality of hollow portions 212d extending along the thickness direction X (arrangement direction X), a partition wall 214d partitioning the plurality of hollow portions 212d, and a flat base portion 216 supporting the partition wall 214d. The hollow portion 212d has a tapered shape along the thickness direction X (arrangement direction X). The partition wall 214d has a trapezoidal shape in a cross-sectional view in the thickness direction X. According to such an aspect, it becomes easier to maintain the hollow portion 212d even when the charge and discharge cycles are repeated, and it becomes easier to stably exhibit the elastic function over a long period. In addition, the yield of the elastic portion 210d can be increased and the manufacturing cost can be reduced.

[0059] As described above, specific aspects of the technology disclosed here include those described in the following items. Item 1: A battery pack including a plurality of rectangular secondary batteries arranged along a predetermined arrangement direction and a spacer arranged between the adjacent rectangular secondary batteries in the arrangement direction, wherein the spacer has a plurality of hollow portions extending along the arrangement direction, an elastic portion configured to be elastically deformable in the arrangement direction, and a heat insulating portion arranged between the elastic portion and the rectangular secondary battery in the arrangement direction and having a lower thermal conductivity than the elastic portion. Item 2: The battery pack according to Item 1, wherein the elastic portion has a honeycomb structure. Item 3: The battery pack according to Item 1 or Item 2, wherein, on a plane perpendicular to the arrangement direction of the elastic portion, the ratio of the total area of the plurality of hollow portions to the total area of the elastic portion is 0.35 or more and 0.8 or less. Item 4: The battery pack according to any one of Items 1 to 3, wherein the area of the plane perpendicular to the arrangement direction of the elastic portion is equal to or less than the area of the plane perpendicular to the arrangement direction of the heat insulating portion. Item 5: The battery pack according to any one of Items 1 to 4, wherein, in the elastic portion, one end of the plurality of hollow portions in the arrangement direction is closed and the other end is open. Item 6: The battery pack according to any one of Items 1 to 5, wherein a part of the elastic portion is arranged inside the heat insulating portion. Item 7: The battery pack according to any one of Items 1 to 6, wherein the elastic portion and the heat insulating portion are integrated by an integrating member. Item 8: The battery pack according to any one of Items 1 to 7, wherein the spacer further includes a flat base portion. Item 9: The battery pack according to any one of Items 1 to 8, wherein the elastic portion has a hole portion communicating the plurality of hollow portions. Item 10: The battery pack according to any one of Items 1 to 9, wherein the hollow portion has a tapered shape along the arrangement direction.

Explanation of Reference Numerals

[0060] 10 Battery case 20 Electrode body 100 Rectangular secondary battery 200 Spacer Elastic parts 210, 210a, 210b, 210c, 210d Hollow parts 212, 212a, 212b, 212c, 212d Partition walls 214, 214a, 214b Base part 216 Heat insulation part 220 Restraint mechanism 300 Battery pack 500

Claims

1. A plurality of rectangular secondary batteries arranged along a predetermined arrangement direction, A spacer disposed between the adjacent rectangular secondary batteries in the arrangement direction, A battery pack comprising: The spacer includes: An elastic portion having a plurality of hollow portions extending along the arrangement direction and configured to be elastically deformable in the arrangement direction, A heat insulating portion disposed between the elastic portion and the rectangular secondary battery in the arrangement direction and having a lower thermal conductivity than the elastic portion, and The battery pack, wherein the elastic portion has a honeycomb structure.

2. On a plane perpendicular to the arrangement direction of the elastic portion, a ratio of a total area of the plurality of hollow portions to an entire area of the elastic portion is 0.35 or more and 0.8 or less, The battery pack according to claim 1.

3. An area of a plane perpendicular to the arrangement direction of the elastic portion is equal to or less than an area of a plane perpendicular to the arrangement direction of the heat insulating portion, The battery pack according to claim 1 or 2.

4. In the elastic portion, one end of the plurality of hollow portions in the arrangement direction is closed and the other end is open, The battery pack according to claim 1 or 2.

5. A part of the elastic portion is disposed within the heat insulating portion, The battery pack according to claim 1 or 2.

6. The elastic portion has a hole portion communicating the plurality of hollow portions, The battery pack according to claim 1 or 2.

7. A plurality of rectangular secondary batteries arranged along a predetermined arrangement direction, A spacer disposed between the adjacent rectangular secondary batteries in the arrangement direction, A battery pack comprising: wherein the spacer: has a plurality of hollow portions extending along the arrangement direction and an elastic portion configured to be elastically deformable in the arrangement direction; and a heat insulating portion disposed between the elastic portion and the rectangular secondary battery in the arrangement direction and having a lower thermal conductivity than the elastic portion; and the elastic portion and the heat insulating portion are integrated by an integrating member. The battery pack. **Claim 8** A plurality of rectangular secondary batteries arranged along a predetermined arrangement direction; a spacer disposed between the adjacent rectangular secondary batteries in the arrangement direction; A battery pack comprising: wherein the spacer: has a plurality of hollow portions extending along the arrangement direction and an elastic portion configured to be elastically deformable in the arrangement direction; and a heat insulating portion disposed between the elastic portion and the rectangular secondary battery in the arrangement direction and having a lower thermal conductivity than the elastic portion; a flat base portion; and **Claim 9** A plurality of rectangular secondary batteries arranged along a predetermined arrangement direction; a spacer disposed between the adjacent rectangular secondary batteries in the arrangement direction; A battery pack comprising: wherein the spacer: has a plurality of hollow portions extending along the arrangement direction and an elastic portion configured to be elastically deformable in the arrangement direction; and a heat insulating portion disposed between the elastic portion and the rectangular secondary battery in the arrangement direction and having a lower thermal conductivity than the elastic portion; and the hollow portions have a tapered shape along the arrangement direction. The battery pack. **Claim 10** A plurality of rectangular secondary batteries arranged along a predetermined arrangement direction; A spacer disposed between the rectangular secondary batteries adjacent to each other in the array direction; A battery pack comprising: The spacer includes: An elastic portion having a plurality of hollow portions extending along the array direction and configured to be elastically deformable in the array direction; A heat insulating portion disposed between the elastic portion and the rectangular secondary battery in the array direction and having a lower thermal conductivity than the elastic portion; and The elastic portion is made of rubber. The battery pack.

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