Battery pack

Abstract

A battery pack 1 comprises a cylindrical secondary battery 40 and a heat absorbing member 70. An exterior body 90 of the heat absorbing member 70 accommodates a heat absorbing agent 80 between a first inner resin layer L1a and a second inner resin layer L2a. A flange part 92 of the exterior body 90 has an inner resin continuous part 92a in which the first inner resin layer L1a and the second inner resin layer L2a are continuous over the entire circumference. In a cross-sectional shape of the heat absorbing member 70, the inner resin continuous part 92a has a first continuous portion 92a1 located on the inner side of a first metal layer L1c and a second metal layer L2c, and has a second continuous portion 92a2, a third continuous portion 92a3, and a fourth continuous portion 92a4 that have sites exposed to the outside of the exterior body 90. The heat absorbing member 70 has a configuration in which the first continuous portion 92a1 is closer to an end of the secondary battery 40 as compared to the second continuous portion 92a2, the third continuous portion 92a3, and the fourth continuous portion 92a4, in the axial direction of the secondary battery 40.

Description

Battery pack

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

[0002] Patent Document 1 discloses, as an example of a battery pack, a battery module including a heat-absorbing member and a plurality of single cells. The heat-absorbing member includes a heat-absorbing agent and an exterior film containing the heat-absorbing agent. When the secondary battery generates abnormal heat, the exterior film tears, and the temperature of the secondary battery drops due to the leaked heat-absorbing agent.

[0003] International Publication No. 2010 / 098067

[0004] However, if the portion where the exterior film tears is relatively close to the edge of the secondary battery, the endothermic agent that flows out of the exterior film may remain near the edge of the secondary battery. In this case, the contact area between the outer surface of the secondary battery and the endothermic agent is relatively small, and the endothermic efficiency is relatively low.

[0005] The present disclosure has been made in view of the above, and has an object to improve the heat absorption efficiency of a heat absorbing agent in a battery pack when a secondary battery generates abnormal heat.

[0006] The battery pack of the present disclosure includes a plurality of cylindrical secondary batteries, and a heat-absorbing member having an exterior body that accommodates a heat-absorbing agent and the heat-absorbing agent, wherein the exterior body includes a first exterior part having a first resin layer and a first metal layer overlapping the first resin layer, and a second exterior part having a second resin layer facing the first resin layer and a second metal layer overlapping the second resin layer, and the battery pack integrally includes a housing part that accommodates the heat-absorbing agent between the first resin layer and the second resin layer, and a flange part around the housing part where the first resin layer and the second resin layer overlap each other over the entire circumference, and the flange part is formed by a continuous first resin layer and a second resin layer. The heat absorption member has a continuous portion extending around the entire periphery of the accommodating portion, the continuous portion having a first portion and a second portion, the first portion being located inside at least one of the first metal layer and the second metal layer in a cross-sectional shape of the heat absorption member when cut along a plane along the thickness direction of the flange portion, the second portion having a portion exposed to the outside of the outer casing in a cross-sectional shape of the heat absorption member when cut along a plane along the thickness direction of the flange portion, and the heat absorption member is arranged in an axial direction in which the central axis of the secondary battery extends, with the first portion closer to an end of the secondary battery than the second portion.

[0007] According to the present disclosure, it is possible to improve the heat absorption efficiency of the heat absorbing agent in a battery pack when the secondary battery generates abnormal heat.

[0008] FIG. 1 is an exploded perspective view of a battery pack according to a first embodiment of the present disclosure. FIG. 2 is an exploded perspective view of a battery unit shown in FIG. 1. FIG. 3 is a longitudinal cross-sectional view of the secondary battery shown in FIG. 2. FIG. 4 is a plan view of a heat-absorbing member. FIG. 5 is a diagram showing a cross-sectional shape of the heat-absorbing member taken along line V-V shown in FIG. 4. FIG. 6 is a diagram showing a cross-sectional shape of the heat-absorbing member taken along line VI-VI shown in FIG. 4. FIG. 7 is a perspective view showing an exterior body before accommodating a heat-absorbing agent. FIG. 8 is a diagram showing the arrangement of the heat-absorbing member as viewed along a direction perpendicular to the axial direction in which the central axis of the secondary battery extends. FIG. 9 is a perspective view of a heat-absorbing member of a battery pack according to a modified example of the first embodiment of the present disclosure. FIG. 10 is a partial cross-sectional view of a battery unit according to a modified example of the first embodiment. FIG. 11 is a perspective view of a set of heat-absorbing members included in a battery pack according to a second embodiment of the present disclosure. FIG. 12 is a plan view of the set of heat-absorbing members shown in FIG. 11. Fig. 13 is a diagram showing the cross-sectional shape of a pair of heat-absorbing members when cut along a plane along the thickness direction of the flange portions of the heat-absorbing members, mainly showing the cross-sectional shape of the connecting portion. Fig. 14 is a perspective view showing the exterior body of a pair of heat-absorbing members before accommodating a heat-absorbing agent.

[0009] Hereinafter, embodiments will be described in detail with reference to the drawings. Note that the present disclosure is not limited to these embodiments. Each embodiment is an example, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments is possible.

[0010] The X direction shown in the drawings corresponds to the width direction of the battery pack 1, the Y direction corresponds to the depth direction of the battery pack 1, and the Z direction corresponds to the height direction of the battery pack 1. The X direction, Y direction, and Z direction are perpendicular to each other. In the X direction, the side indicated by the arrow is the +X side, and the side opposite the +X side is the -X side. In the Y direction, the side indicated by the arrow is the +Y side, and the side opposite the +Y side is the -Y side. In the Z direction, the side indicated by the arrow is the +Z side, and the side opposite the +Z side is the -Z side. Note that the X, Y, and Z directions are merely examples, and the present disclosure is not limited to these directions.

[0011] 1 is an exploded perspective view of a battery pack 1 according to a first embodiment of the present disclosure. The battery pack 1 can be used as a power source for external devices (not shown), such as electronic devices, electric vehicles, and power tools. The battery pack 1 includes an outer case 10, a control board 20, and a battery unit 30.

[0012] The exterior case 10 is box-shaped and houses the control board 20 and the battery unit 30. The exterior case 10 has a first case portion 11 and a second case portion 12.

[0013] A connector 13 is also attached to the exterior case 10. The connector 13 electrically connects an external device and the battery unit 30 via a control board 20, and supplies (discharges) power from the battery unit 30 to the external device. The connector 13 also electrically connects a power source (e.g., a commercial power source) and the battery unit 30 via the control board 20, and supplies (charges) power from the power source to the battery unit 30. The control board 20 controls charging and discharging of the battery unit 30.

[0014] Fig. 2 is an exploded perspective view of the battery unit 30 shown in Fig. 1. The battery unit 30 includes a plurality of secondary batteries 40, a plurality of lead plates 50, a holder 60, and a plurality of heat-absorbing members 70.

[0015] The secondary batteries 40 are, for example, lithium ion batteries. The secondary batteries 40 are cylindrical. The secondary batteries 40 have a positive terminal 40a and a negative terminal 40b, which are electrodes, at both ends. In the first embodiment, the number of secondary batteries 40 is eight. However, it goes without saying that the number of secondary batteries 40 is not limited to eight.

[0016] The multiple secondary batteries 40 are arranged in parallel and spaced apart from each other. The central axes CL of the multiple secondary batteries 40 are parallel to each other. In the first embodiment, the central axes CL of the secondary batteries 40 are aligned along the Y direction. The multiple secondary batteries 40 are also arranged such that the positive electrode terminals 40a and the negative electrode terminals 40b are oriented in predetermined directions.

[0017] The plurality of secondary batteries 40 are arranged in two rows. Specifically, four secondary batteries 40 are arranged along the X direction, and two secondary batteries 40 are arranged along the Y direction. It goes without saying that the arrangement of the plurality of secondary batteries 40 is not limited to two rows.

[0018] Fig. 3 is a longitudinal cross-sectional view of the secondary battery 40 shown in Fig. 2. The secondary battery 40 includes an electrode assembly 41, a can 42, and a lid 43. The can 42 and the lid 43 are made of, for example, iron, stainless steel, or aluminum, and are electrically conductive.

[0019] The electrode assembly 41 is formed by stacking a plurality of sheet-shaped positive electrodes (not shown) and a plurality of sheet-shaped negative electrodes (not shown) with separators (not shown) interposed therebetween and winding them up.

[0020] The can 42 is cylindrical and has an opening at one end. The can 42 is electrically connected to the negative electrode of the electrode assembly 41 via a current collector foil (not shown). The center of the other end face of the can 42 is the negative electrode terminal 40b of the secondary battery 40.

[0021] The lid 43 is plate-shaped and covers the opening at one end of the can 42. The lid 43 and the can 42 are electrically insulated by an insulating member (not shown). The lid 43 is electrically connected to the positive electrode of the electrode assembly 41 via a current collecting foil.

[0022] The lid 43 has a protrusion 43a and a split valve 43b. The protrusion 43a is located in the center of the lid 43. The protruding end surface of the protrusion 43a is the positive electrode terminal 40a of the secondary battery 40. The protrusion 43a is also provided with a hole 43a1 that connects the inside and outside of the secondary battery 40. There may be multiple holes 43a1.

[0023] The split valve 43b is located inside the protrusion 43a inside the secondary battery 40. The split valve 43b separates the space inside the secondary battery 40 that communicates with the hole 43a1 from the space in which the electrode assembly 41 is located. The split valve 43b splits to open when the internal pressure of the secondary battery 40 reaches or exceeds a predetermined value.

[0024] Furthermore, a battery thin portion 42a is provided on the other end of the can 42. The battery thin portion 42a is a portion where the thickness is thinner on the other end of the can 42. When the internal pressure of the secondary battery 40 increases, the other end of the can 42 splits open from the battery thin portion 42a. For example, if the split valve 43b does not open even when the internal pressure of the secondary battery 40 reaches or exceeds a predetermined value, when the internal pressure of the secondary battery 40 further increases, the other end of the can 42 splits open from the battery thin portion 42a.

[0025] The lead-plates 50 shown in Figure 2 electrically connect multiple secondary batteries 40 in series or parallel. The lead-plates 50 also electrically connect the multiple secondary batteries 40 to the control board 20. The lead-plates 50 include a first lead-plate 51 and a second lead-plate 52. The first lead-plate 51 electrically connects two secondary batteries 40. The second lead-plate 52 electrically connects four secondary batteries 40. It goes without saying that the number of secondary batteries 40 electrically connected to the first lead-plate 51 and the second lead-plate 52 is not limited to the above number.

[0026] The holder 60 holds a plurality of secondary batteries 40 and a plurality of heat absorption members 70. The holder 60 includes a first holder member 61 and a second holder member 62. The first holder member 61 holds the -Y sides of the plurality of secondary batteries 40. The second holder member 62 holds the +Y sides of the plurality of secondary batteries 40.

[0027] The heat absorbing members 70 absorb heat from the secondary batteries 40. The number of heat absorbing members 70 is six, but it goes without saying that the number is not limited to six and varies depending on the number and arrangement of the secondary batteries 40.

[0028] Fig. 4 is a plan view of the heat absorbing member 70. Fig. 4 corresponds to a plan view of the heat absorbing member 70 when viewed along the thickness direction of a flange portion 92, which will be described later.

[0029] Fig. 5 is a diagram showing the cross-sectional shape of the heat absorption member 70 taken along line V-V shown in Fig. 4. Fig. 6 is a diagram showing the cross-sectional shape of the heat absorption member 70 taken along line VI-VI shown in Fig. 4. The cross-sectional shapes in Figs. 5 and 6 correspond to the cross-sectional shape of the heat absorption member 70 when cut along a plane along the thickness direction of a flange portion 92, which will be described later.

[0030] In the plan view of the heat absorption member 70 shown in Fig. 4 and the cross-sectional shape of the heat absorption member 70 shown in Fig. 5, the first direction W1 corresponds to the direction in which line V-V shown in Fig. 4 extends. The "S1 side" indicated by the arrow in the first direction W1 corresponds to the side from an accommodation section 91 (described later) toward a first side S1 of the flange section 92 in the first direction W1 in the plan view of the heat absorption member 70 shown in Fig. 4. The "S2 side" indicated by the arrow in the first direction W1 corresponds to the side from an accommodation section 91 (described later) toward a second side S2 of the flange section 92 in the first direction W1 in the plan view of the heat absorption member 70 shown in Fig. 4.

[0031] In addition, in the plan view of the heat absorption member 70 shown in Fig. 4 and the cross-sectional shape of the heat absorption member 70 shown in Fig. 6, the second direction W2 corresponds to the direction in which the line VI-VI shown in Fig. 4 extends. The "S3 side" indicated by the arrow in the second direction W2 corresponds to the side from the accommodation section 91 (described later) toward the third side S3 of the flange section 92 in the second direction W2 in the plan view of the heat absorption member 70 shown in Fig. 4. The "S4 side" indicated by the arrow in the second direction W2 corresponds to the side from the accommodation section 91 (described later) toward the fourth side S4 of the flange section 92 in the second direction W2 in the plan view of the heat absorption member 70 shown in Fig. 4.

[0032] 5 and 6, the third direction W3 is a direction perpendicular to the first direction W1 and the second direction W2. The "V1 side" indicated by the arrow in the third direction W3 corresponds to the side from the second convex portion 90b1 to the first convex portion 90a1 of the accommodation portion 91 (described later) in the third direction W3 in the cross-sectional shape of the heat absorption member 70 shown in Figures 5 and 6. The "V2 side" indicated by the arrow in the third direction W3 corresponds to the side from the first convex portion 90a1 to the second convex portion 90b1 of the accommodation portion 91 (described later) in the third direction W3 in the cross-sectional shape of the heat absorption member 70 shown in Figures 5 and 6.

[0033] In the plan view of the heat absorption member 70 shown in Fig. 4, a first imaginary line Li1 is an imaginary line connecting the third side S3 and the fourth side S4 on the S1 side of the accommodation portion 91 in the first direction W1. A first imaginary line portion Li1a included in the first imaginary line Li1 corresponds to a portion of the first imaginary line Li1 between a first connection point Ps1 between the first imaginary line Li1 and a third imaginary line Li3 (described later) and a second connection point Ps2 between the first imaginary line Li1 and a fourth imaginary line Li4 (described later). In the plan view of the heat absorption member 70 shown in Fig. 4, the first imaginary line portion Li1a overlaps with a fifth imaginary point P5 (described later) (see Fig. 5).

[0034] In the plan view of the heat absorption member 70 shown in Fig. 4, the second imaginary line Li2 is an imaginary line connecting the third side S3 and the fourth side S4 on the S2 side of the accommodation portion 91 in the first direction W1. A second imaginary line portion Li2a of the second imaginary line Li2 corresponds to a portion of the second imaginary line Li2 between a third connection point Ps3 between the second imaginary line Li2 and a third imaginary line Li3 (described later) and a fourth connection point Ps4 between the second imaginary line Li2 and a fourth imaginary line Li4 (described later) in the plan view of the heat absorption member 70 shown in Fig. 4. The second imaginary line portion Li2a overlaps with a second imaginary point P2 (see Fig. 5) (described later) in the plan view of the heat absorption member 70 shown in Fig. 4.

[0035] 4, a third imaginary line Li3 is an imaginary line that connects the first imaginary line Li1 and the second imaginary line Li2 on the S3 side of the center of the accommodation section 91 in the second direction W2. In the plan view of the heat absorption member 70 shown in FIG. 4, the third imaginary line Li3 overlaps with a third imaginary point P3 (see FIG. 6), which will be described later.

[0036] In the plan view of the heat absorption member 70 shown in Fig. 4, the fourth imaginary line Li4 is an imaginary line that connects the first imaginary line Li1 and the second imaginary line Li2 on the S4 side from the center of the accommodation section 91 in the second direction W2. In the plan view of the heat absorption member 70 shown in Fig. 4, the fourth imaginary line Li4 overlaps with a fourth imaginary point P4 (see Fig. 6) described later.

[0037] It goes without saying that in the plan view of the heat absorption member 70 shown in Fig. 4, the first imaginary line Li1, the second imaginary line Li2, the third imaginary line Li3, and the fourth imaginary line Li4 are not limited to the positions shown in Fig. 4. In addition, in the plan view of the heat absorption member 70 shown in Fig. 4, the first imaginary line Li1 and the second imaginary line Li2 may be curved. In addition, in the plan view of the heat absorption member 70 shown in Fig. 4, the third imaginary line Li3 and the fourth imaginary line Li4 may be straight.

[0038] The heat absorbing member 70 has a heat absorbing agent 80 and an exterior body 90 that houses the heat absorbing agent 80 .

[0039] The heat-absorbing agent 80 contains a substance that absorbs heat generated by the secondary battery 40. The main component of the heat-absorbing agent 80 is a liquid such as water. The heat-absorbing agent 80 may also contain a gelling agent, a surfactant, and an antifreeze agent. The heat-absorbing agent 80 has fluidity.

[0040] As shown in FIGS. 5 and 6, the exterior body 90 includes a first exterior portion 90a and a second exterior portion 90b.

[0041] The first exterior part 90a has a first inner resin layer L1a (corresponding to the "first resin layer"), a first outer resin layer L1b, and a first metal layer L1c between the first inner resin layer L1a and the first outer resin layer L1b. In the cross-sectional shape of the heat-absorbing member 70 shown in Figures 5 and 6, the first inner resin layer L1a, the first metal layer L1c, and the first outer resin layer L1b are stacked in this order.

[0042] The second exterior part 90b includes a second inner resin layer L2a (corresponding to the "second resin layer"), a second outer resin layer L2b, and a second metal layer L2c between the second inner resin layer L2a and the second outer resin layer L2b. In the cross-sectional shape of the heat-absorbing member 70 shown in Figures 5 and 6, the second inner resin layer L2a, the second metal layer L2c, and the second outer resin layer L2b are stacked in this order. In the cross-sectional shape of the heat-absorbing member 70 shown in Figures 5 and 6, the first inner resin layer L1a and the second inner resin layer L2a face each other.

[0043] The material of the first inner resin layer L1a, the first outer resin layer L1b, the second inner resin layer L2a, and the second outer resin layer L2b is, for example, polyethylene terephthalate alone, but may also be a synthetic resin containing at least one of nylon, polyethylene terephthalate, polypropylene, polyethylene, and polystyrene.

[0044] The first metal layer L1c and the second metal layer L2c are made of, for example, aluminum, and have a higher melting point than the first inner resin layer L1a, the first outer resin layer L1b, the second inner resin layer L2a, and the second outer resin layer L2b.

[0045] The exterior body 90 also has a storage section 91 between the first inner resin layer L1a and the second inner resin layer L2a that stores the heat-absorbing agent 80. The first exterior section 90a and the second exterior section 90b have first and second convex sections 90a1 and 90b1 that protrude toward the outside of the heat-absorbing member 70 at the center of the exterior body 90 in the first direction W1 and the center of the second direction W2. The heat-absorbing agent 80 is stored in the space inside the first and second convex sections 90a1 and 90b1. Hereinafter, the portion formed by the first and second convex sections 90a1 and 90b1 corresponds to the storage section 91.

[0046] In the cross-sectional shape of the heat absorption member 70 shown in Fig. 5 , the accommodation portion 91 is located between a fifth imaginary line Li5 and a sixth imaginary line Li6 in the first direction W1. The fifth imaginary line Li5 is an imaginary line that includes a first imaginary point P1 and extends along the third direction W3 in the cross-sectional shape of the heat absorption member 70 shown in Fig. 5. The first imaginary point P1 is the point where the first inner resin layer L1a and the second inner resin layer L2a overlap when viewed from inside the accommodation portion 91 toward the S1 side in the first direction W1 in the cross-sectional shape of the heat absorption member 70 shown in Fig. 5 .

[0047] The sixth imaginary line Li6 is an imaginary line that includes the second imaginary point P2 and extends along the third direction W3 in the cross-sectional shape of the heat absorption member 70 shown in Fig. 5. The second imaginary point P2 is a point where the first inner resin layer L1a and the second inner resin layer L2a overlap when viewed from inside the accommodation portion 91 toward the S2 side along the first direction W1 in the cross-sectional shape of the heat absorption member 70 shown in Fig. 5. As described above, the second imaginary point P2 overlaps with the second imaginary line portion Li2a of the second imaginary line Li2 in the plan view of the heat absorption member 70 shown in Fig. 4.

[0048] In addition, in the cross-sectional shape of the heat absorption member 70 shown in Fig. 6 , the accommodation portion 91 is located between the seventh imaginary line Li7 and the eighth imaginary line Li8 in the second direction W2. The seventh imaginary line Li7 is an imaginary line that includes the third imaginary point P3 and extends along the third direction W3 in the cross-sectional shape of the heat absorption member 70 shown in Fig. 6 . The third imaginary point P3 is the point where the first inner resin layer L1a and the second inner resin layer L2a overlap when viewed from inside the accommodation portion 91 toward the S3 side along the second direction W2 in the cross-sectional shape of the heat absorption member 70 shown in Fig. 6 . As described above, the third imaginary point P3 overlaps with the third imaginary line Li3 in the plan view of the heat absorption member 70 shown in Fig. 4 .

[0049] The eighth imaginary line Li8 is an imaginary line that includes the fourth imaginary point P4 and extends along the third direction W3 in the cross-sectional shape of the heat absorption member 70 shown in Fig. 6. The fourth imaginary point P4 is a point where the first inner resin layer L1a and the second inner resin layer L2a overlap when viewed from inside the accommodation portion 91 toward the S4 side along the second direction W2 in the cross-sectional shape of the heat absorption member 70 shown in Fig. 6. As described above, the fourth imaginary point P4 overlaps with the fourth imaginary line Li4 in the plan view of the heat absorption member 70 shown in Fig. 4.

[0050] Furthermore, the exterior body 90 has a flange portion 92 integral with the accommodation portion 91. In the plan view of the heat absorption member 70 shown in FIG. 4 , the flange portion 92 is a portion provided around the entire periphery of the accommodation portion 91. The flange portion 92 is also a portion where the first inner resin layer L1a and the second inner resin layer L2a overlap (see FIGS. 5 and 6 ). Specifically, the flange portion 92 is continuous with the accommodation portion 91 and extends around the entire periphery of the accommodation portion 91 in the plan view of the heat absorption member 70 shown in FIG. 4 . In the plan view of the heat absorption member 70 shown in FIG. 4 , the outer periphery of the flange portion 92 corresponds to the outer periphery of the exterior body 90.

[0051] 5, the flange portion 92 is located on the S1 side of the fifth imaginary line Li5 in the first direction W1 and on the S2 side of the sixth imaginary line Li6 in the first direction W1. In addition, in the cross-sectional shape of the heat absorption member 70 shown in FIG. 6, the flange portion 92 is located on the S3 side of the seventh imaginary line Li7 in the second direction W2 and on the S4 side of the eighth imaginary line Li8 in the second direction W2.

[0052] In the plan view of the heat absorption member 70 shown in FIG. 4 , the outer periphery of the flange portion 92 has a shape having a first side S1, a second side S2, a third side S3, and a fourth side S4. In the plan view of the heat absorption member 70 shown in FIG. 4 , the second side S2 is located on the opposite side of the first side S1 across the accommodation portion 91. The third side S3 connects a first end of the first side S1 to a first end of the second side S2. The fourth side S4 connects a second end of the first side S1 to a second end of the second side S2. In the plan view of the heat absorption member 70 shown in FIG. 4 , the fourth side S4 is located on the opposite side of the third side S3 across the accommodation portion 91. In this first embodiment, the first side S1, the second side S2, the third side S3, and the fourth side S4 are linear. The first side S1, the second side S2, the third side S3 and the fourth side S4 may be curved.

[0053] 4 , the flange portion 92 has an inner resin continuous portion 92a (corresponding to a "continuous portion") where the first inner resin layer L1a and the second inner resin layer L2a are continuous, and the inner resin continuous portion 92a extends around the entire periphery of the accommodation portion 91. The inner resin continuous portion 92a is a portion in the flange portion 92 where the first inner resin layer L1a and the second inner resin layer L2a are continuous. In other words, in the inner resin continuous portion 92a, the base material of the first inner resin layer L1a and the base material of the second inner resin layer L2a are integrated, and the first inner resin layer L1a and the second inner resin layer L2a are connected to each other.

[0054] The inner resin continuous portion 92a is a patterned portion in the plan view of the heat absorption member 70 shown in Fig. 4. In the plan view of the heat absorption member 70 shown in Fig. 4, the inner resin continuous portion 92a surrounds the entire periphery of the accommodation portion 91. In the plan view of the heat absorption member 70 shown in Fig. 4, the outer periphery of the inner resin continuous portion 92a is defined by a first side S1, a second side S2, a third side S3, and a fourth side S4. In addition, in the plan view of the heat absorption member 70 shown in Fig. 4, the inner periphery of the inner resin continuous portion 92a is defined by a first imaginary line portion Li1a of the first imaginary line Li1, a second imaginary line portion Li2a of the second imaginary line Li2, a third imaginary line Li3, and a fourth imaginary line Li4.

[0055] The inner resin continuous portion 92a integrally has a first continuous portion 92a1 (corresponding to the "first portion"), a second continuous portion 92a2 (corresponding to the "second portion" and the "first second portion"), a third continuous portion 92a3 (corresponding to the "second portion" and the "second second portion"), and a fourth continuous portion 92a4 (corresponding to the "second portion" and the "second second portion").

[0056] In the plan view of the heat absorption member 70 shown in Fig. 4, the first continuous portion 92a1 is the portion of the inner resin continuous portion 92a that is on the first side S1 side of the flange portion 92. Specifically, in the plan view of the heat absorption member 70 shown in Fig. 4, the first continuous portion 92a1 is the portion of the inner resin continuous portion 92a that is surrounded by the first side S1, the first imaginary line Li1, the third side S3, and the fourth side S4.

[0057] In the plan view of the heat absorption member 70 shown in Fig. 4, the second continuous portion 92a2 is the portion of the inner resin continuous portion 92a that is on the second side S2 side of the flange portion 92. Specifically, in the plan view of the heat absorption member 70 shown in Fig. 4, the second continuous portion 92a2 is the portion of the inner resin continuous portion 92a that is surrounded by the second side S2, the second imaginary line Li2, the third side S3, and the fourth side S4.

[0058] In the plan view of the heat absorption member 70 shown in Fig. 4, the third continuous portion 92a3 is the portion of the inner resin continuous portion 92a that is on the third side S3 side of the flange portion 92. Specifically, in the plan view of the heat absorption member 70 shown in Fig. 4, the third continuous portion 92a3 is the portion of the inner resin continuous portion 92a that is surrounded by the third side S3, the third imaginary line Li3, the first imaginary line Li1, and the second imaginary line Li2.

[0059] In the plan view of the heat absorption member 70 shown in Fig. 4, the fourth continuous portion 92a4 is the portion of the inner resin continuous portion 92a that is on the fourth side S4 side of the flange portion 92. Specifically, in the plan view of the heat absorption member 70 shown in Fig. 4, the fourth continuous portion 92a4 is the portion of the inner resin continuous portion 92a that is surrounded by the fourth side S4, the fourth imaginary line Li4, the first imaginary line Li1, and the second imaginary line Li2.

[0060] In the cross-sectional shape of the heat absorption member 70 shown in Fig. 5, the first continuous portion 92a1 is located on the S1 side of the ninth imaginary line Li9 in the first direction W1. The ninth imaginary line Li9 is an imaginary line that includes the fifth imaginary point P5 and extends along the third direction W3 in the cross-sectional shape of the heat absorption member 70 shown in Fig. 5. As described above, the fifth imaginary point P5 overlaps with the first imaginary line portion Li1a in the plan view of the heat absorption member 70 shown in Fig. 4.

[0061] For ease of explanation, a tenth imaginary line Li10 is shown in the cross-sectional shape of the heat-absorbing member 70 shown in Fig. 5. The tenth imaginary line Li10 is an imaginary line extending from the fifth imaginary point P5 toward the S1 side along the first direction W1 in the cross-sectional shape of the heat-absorbing member 70 shown in Fig. 5. The tenth imaginary line Li10 corresponds to the boundary line between the first inner resin layer L1a and the second inner resin layer L2a (a boundary line for ease of explanation: the same applies hereinafter), the boundary line between the first metal layer L1c and the second metal layer L2c, and the boundary line between the first outer resin layer L1b and the second outer resin layer L2b in the cross-sectional shape of the heat-absorbing member 70 shown in Fig. 5.

[0062] 5, the solid line connecting the first imaginary point P1 and the fifth imaginary point P5 indicates a state in which the surface of the first inner resin layer L1a and the surface of the second inner resin layer L2a overlap in the flange portion 92. In other words, in the cross-sectional shape of the heat absorption member 70 shown in Fig. 5, the first inner resin layer L1a and the second inner resin layer L2a are not continuous in the region of the flange portion 92 between the fifth imaginary line Li5 including the first imaginary point P1 and the ninth imaginary line Li9 including the fifth imaginary point P5 in the first direction W1, and the base material of the first inner resin layer L1a and the base material of the second inner resin layer L2a are not integrated.

[0063] Furthermore, the first continuous portion 92a1 is a portion of the inner resin continuous portion 92a that is entirely inside at least one of the first metal layer L1c and the second metal layer L2c in the cross-sectional shape of the heat absorption member 70 shown in Fig. 5 . Specifically, in the cross-sectional shape of the heat absorption member 70 shown in Fig. 5 , the entire first continuous portion 92a1 is inside the metal continuous portion 92b where the first metal layer L1c and the second metal layer L2c are continuous. In the cross-sectional shape of the heat absorption member 70 shown in Fig. 5 , the metal continuous portion 92b is a portion of the first metal layer L1c and the second metal layer L2c that is on the S1 side of the ninth imaginary line Li9 in the first direction W1. The metal continuous portion 92b is a portion where the base material of the first metal layer L1c and the base material of the second metal layer L2c are integrated, and where the first metal layer L1c and the second metal layer L2c are continuously connected without interruption. In the cross-sectional shape of the heat absorption member 70 shown in Fig. 5, the entire outer surface of the first continuous portion 92a1 overlaps with the inner surface of the metal continuous portion 92b. Note that the metal continuous portion 92b may be composed of either the first metal layer L1c or the second metal layer L2c. In this case, the boundary between the first metal layer L1c and the second metal layer L2c is located between the fifth imaginary line Li5 and the ninth imaginary line Li9 in the first direction W1 in the cross-sectional shape of the heat absorption member 70 shown in Fig. 5.

[0064] In the cross-sectional shape of the heat absorption member 70 shown in Fig. 5 , the entire first continuous portion 92a1 overlaps with the metal continuous portion 92b when the flange portion 92 is viewed from the S1 side. That is, in the cross-sectional shape of the heat absorption member 70 shown in Fig. 5 , the first continuous portion 92a1 is not exposed to the outside of the exterior body 90 when the flange portion 92 is viewed from the S1 side. In the cross-sectional shape of the heat absorption member 70 shown in Fig. 5 , the first inner resin layer L1a between the fifth imaginary line Li5 and the ninth imaginary line Li9 in the first direction W1 overlaps with the first metal layer L1c. In addition, in the cross-sectional shape of the heat absorption member 70 shown in Fig. 5 , the second inner resin layer L2a between the fifth imaginary line Li5 and the ninth imaginary line Li9 in the first direction W1 overlaps with the second metal layer L2c. 5 , the first inner resin layer L1a and the second inner resin layer L2a between the fifth imaginary line Li5 and the ninth imaginary line Li9 in the first direction W1 are not exposed to the outside of the exterior body 90. Therefore, in the cross-sectional shape of the heat-absorbing member 70 shown in FIG. 5 , the first continuous portion 92a1, the first inner resin layer L1a, and the second inner resin layer L2a are not exposed to the outside of the exterior body 90 on the S1 side of the fifth imaginary line Li5 in the first direction W1.

[0065] In the cross-sectional shape of the heat absorption member 70 shown in Fig. 5, the second continuous portion 92a2 is located on the S2 side of the sixth imaginary line Li6 in the first direction W1. For convenience of explanation, an eleventh imaginary line Li11 is also shown in the cross-sectional shape of the heat absorption member 70 shown in Fig. 5. The eleventh imaginary line Li11 is an imaginary line that extends from the second imaginary point P2 toward the S2 side along the first direction W1 in the cross-sectional shape of the heat absorption member 70 shown in Fig. 5. The eleventh imaginary line Li11 corresponds to the boundary line between the first inner resin layer L1a and the second inner resin layer L2a in the cross-sectional shape of the heat absorption member 70 shown in Fig. 5.

[0066] Furthermore, in the cross-sectional shape of the heat absorption member 70 shown in Fig. 5, the second continuous portion 92a2 has a portion that is exposed to the outside of the exterior body 90. Specifically, in the cross-sectional shape of the heat absorption member 70 shown in Fig. 5, a portion of the second continuous portion 92a2 is exposed to the outside when the flange portion 92 is viewed from the S2 side to the S1 side along the first direction W1. In the cross-sectional shape of the heat absorption member 70 shown in Fig. 5, the second continuous portion 92a2 is sandwiched between the first metal layer L1c and the second metal layer L2c with the first metal layer L1c and the second metal layer L2c spaced apart from each other.

[0067] The third continuous portion 92a3 is located on the S3 side of the seventh imaginary line Li7 in the second direction W2 in the cross-sectional shape of the heat absorption member 70 shown in Fig. 6. For convenience of explanation, a twelfth imaginary line Li12 is also shown in the cross-sectional shape of the heat absorption member 70 shown in Fig. 6. The twelfth imaginary line Li12 is an imaginary line that extends from the third imaginary point P3 toward the S3 side along the second direction W2 in the cross-sectional shape of the heat absorption member 70 shown in Fig. 6. The twelfth imaginary line Li12 corresponds to the boundary line between the first inner resin layer L1a and the second inner resin layer L2a in the cross-sectional shape of the heat absorption member 70 shown in Fig. 6.

[0068] In the cross-sectional shape of the heat absorption member 70 shown in Fig. 6, the third continuous portion 92a3 has a portion that is exposed to the outside of the exterior body 90. Specifically, in the cross-sectional shape of the heat absorption member 70 shown in Fig. 6, a portion of the third continuous portion 92a3 is exposed to the outside of the exterior body 90 when the flange portion 92 is viewed from the S3 side to the S4 side along the second direction W2. In the cross-sectional shape of the heat absorption member 70 shown in Fig. 6, the third continuous portion 92a3 is sandwiched between the first metal layer L1c and the second metal layer L2c with the first metal layer L1c and the second metal layer L2c spaced apart from each other.

[0069] The fourth continuous portion 92a4 is located on the S4 side of the eighth imaginary line Li8 in the second direction W2 in the cross-sectional shape of the heat absorption member 70 shown in Fig. 6. For convenience of explanation, a thirteenth imaginary line Li13 is also shown in the cross-sectional shape of the heat absorption member 70 shown in Fig. 6. The thirteenth imaginary line Li13 is an imaginary line that extends from the fourth imaginary point P4 toward the S4 side along the second direction W2 in the cross-sectional shape of the heat absorption member 70 shown in Fig. 6. The thirteenth imaginary line Li13 corresponds to the boundary line between the first inner resin layer L1a and the second inner resin layer L2a in the cross-sectional shape of the heat absorption member 70 shown in Fig. 6.

[0070] In the cross-sectional shape of the heat absorption member 70 shown in Fig. 6, the fourth continuous portion 92a4 has a portion that is exposed to the outside of the exterior body 90. Specifically, in the cross-sectional shape of the heat absorption member 70 shown in Fig. 6, a portion of the third continuous portion 92a3 is exposed to the outside of the exterior body 90 when the flange portion 92 is viewed from the S4 side to the S3 side along the second direction W2. In the cross-sectional shape of the heat absorption member 70 shown in Fig. 6, the fourth continuous portion 92a4 is sandwiched between the first metal layer L1c and the second metal layer L2c with the first metal layer L1c and the second metal layer L2c spaced apart from each other.

[0071] In addition, in the cross-sectional shape of the heat absorption member 70 shown in Fig. 5 , the flange portion 92 has an outer resin continuous portion 92c on the S1 side, where the first outer resin layer L1b and the second outer resin layer L2b are continuous. In the cross-sectional shape of the heat absorption member 70 shown in Fig. 5 , the outer resin continuous portion 92c is located outside the metal continuous portion 92b. In the cross-sectional shape of the heat absorption member 70 shown in Fig. 5 , the outer resin continuous portion 92c is a portion of the first outer resin layer L1b and the second outer resin layer L2b that is on the S1 side of the ninth imaginary line Li9 in the first direction W1. In the outer resin continuous portion 92c, the base material of the first outer resin layer L1b and the base material of the second outer resin layer L2b are integrated, and the first outer resin layer L1b and the second outer resin layer L2b are continuous without interruption. In the cross-sectional shape of the heat absorption member 70 shown in Fig. 5, the entire outer surface of the metal continuous portion 92b overlaps with the inner surface of the outer resin continuous portion 92c. The outer resin continuous portion 92c may be composed of either the first outer resin layer L1b or the second outer resin layer L2b. In this case, the boundary between the first outer resin layer L1b and the second outer resin layer L2b is located between the fifth imaginary line Li5 and the ninth imaginary line Li9 in the first direction W1 in the cross-sectional shape of the heat absorption member 70 shown in Fig. 5.

[0072] In the cross-sectional shape of the heat-absorbing member 70 shown in FIG. 5, on the S2 side of the flange portion 92, the first outer resin layer L1b and the second outer resin layer L2b are spaced apart from each other with the first metal layer L1c and the second metal layer L2c sandwiched therebetween.

[0073] In the cross-sectional shape of the heat absorption member 70 shown in Figure 6, on the S3 side and S4 side of the flange portion 92, the first outer resin layer L1b and the second outer resin layer L2b are separated from each other while sandwiching the first metal layer L1c and the second metal layer L2c.

[0074] In addition, in the plan view of the heat absorption member 70 shown in FIG. 4 , the first distance D1 between the second side S2 and the inner periphery of the second continuous portion 92a2 is shorter than the second distance D2 between the third side S3 and the inner periphery of the third continuous portion 92a3 and the third distance D3 between the fourth side S4 and the inner periphery of the fourth continuous portion 92a4. The second distance D2 and the third distance D3 are substantially equal. The inner periphery of the second continuous portion 92a2 corresponds to the second imaginary line Li2a in the plan view of the heat absorption member 70 shown in FIG. 4 . The inner periphery of the third continuous portion 92a3 corresponds to the third imaginary line Li3 in the plan view of the heat absorption member 70 shown in FIG. 4 . The inner periphery of the fourth continuous portion 92a4 corresponds to the fourth imaginary line Li4 in the plan view of the heat absorption member 70 shown in FIG. 4 . In the plan view of the heat absorption member 70 shown in Fig. 4, the first distance D1 corresponds to the shortest distance between the inner periphery of the second continuous portion 92a2 and the outer periphery of the portion of the second continuous portion 92a2 that is exposed to the outside of the exterior body 90. In the plan view of the heat absorption member 70 shown in Fig. 4, the second distance D2 corresponds to the shortest distance between the inner periphery of the third continuous portion 92a3 and the outer periphery of the portion of the third continuous portion 92a3 that is exposed to the outside of the exterior body 90. In the plan view of the heat absorption member 70 shown in Fig. 4, the third distance D3 corresponds to the shortest distance between the inner periphery of the fourth continuous portion 92a4 and the outer periphery of the portion of the fourth continuous portion 92a4 that is exposed to the outside of the exterior body 90.

[0075] Next, the manufacturing process of the heat absorbing member 70 will be described.

[0076] 7 is a perspective view showing the exterior body 90 before the heat-absorbing agent 80 is accommodated therein. Before the heat-absorbing agent 80 is accommodated therein, the first exterior portion 90a and the second exterior portion 90b are continuous at a portion corresponding to the first side S1 (the portion indicated by the dashed line) in a state in which the first inner resin layer L1a and the second inner resin layer L2a do not face each other. The first convex portion 90a1 and the second convex portion 90b1 are formed, for example, by press working. In other words, before the heat-absorbing agent 80 is accommodated therein, the exterior body 90 is formed by press working a single sheet member.

[0077] The manufacturing process of the heat-absorbing member 70 includes a pouring step, a bending step, and a welding step. The pouring step, the bending step, and the welding step are performed in this order. The pouring step is a step of pouring the heat-absorbing agent 80 into the inside of at least one of the first convex portion 90a1 and the second convex portion 90b1 of the exterior body 90 shown in FIG. 7 .

[0078] The folding step is a step of folding the exterior body 90 at a portion (the portion indicated by the dashed line) corresponding to the first side S1 of the exterior body 90 shown in Fig. 7. The exterior body 90 is folded so that the first inner resin layer L1a and the second inner resin layer L2a face each other and overlap each other (see Figs. 5 and 6).

[0079] The bending process forms a first continuous portion 92a1 of the inner resin continuous portion 92a, a metal continuous portion 92b, and an outer resin continuous portion 92c, as shown in Fig. 5. That is, the first continuous portion 92a1, the metal continuous portion 92b, and the outer resin continuous portion 92c correspond to the portion where the first exterior portion 90a and the second exterior portion 90b are continuous in the exterior body 90 before the heat-absorbing agent 80 is placed inside.

[0080] The welding process is a process of welding (e.g., ultrasonic welding) the first inner resin layer L1a and the second inner resin layer L2a together. The welding process forms the second continuous portion 92a2, the third continuous portion 92a3, and the fourth continuous portion 92a4 of the inner resin continuous portion 92a shown in Figures 4, 5, and 6. That is, the second continuous portion 92a2, the third continuous portion 92a3, and the fourth continuous portion 92a4 correspond to the portions where the first inner resin layer L1a and the second inner resin layer L2a are continuous by welding the first inner resin layer L1a and the second inner resin layer L2a together. Completion of the welding process results in the formation of the housing portion 91 and the flange portion 92, completing the heat-absorbing member 70.

[0081] Next, the arrangement of the heat absorbing member 70 will be described.

[0082] The heat absorption member 70 is surrounded by four secondary batteries 40. Specifically, as shown in Fig. 6, the outer peripheral surfaces of two secondary batteries 40 contact the outer surface of the first protrusion 90a1, and the outer peripheral surfaces of two secondary batteries 40 contact the outer surface of the second protrusion 90b1.

[0083] 8 is a diagram showing the arrangement of the secondary battery 40 and the heat absorption member 70 when viewed along a direction perpendicular to the axial direction along the central axis CL of the secondary battery 40. In FIG. 8, the axial direction is along the Y direction, and the direction perpendicular to the axial direction is along the Z direction.

[0084] The two heat absorbing members 70 are arranged side by side in the axial direction. The longitudinal direction of the heat absorbing members 70 is along the axial direction. The two heat absorbing members 70 arranged side by side in the axial direction are spaced apart from each other.

[0085] Furthermore, the heat absorption members 70 are disposed in an axial direction such that the first continuous portion 92a1 is closer to the end of the secondary battery 40 (specifically, one of the positive electrode terminal 40a and the negative electrode terminal 40b) than the second continuous portion 92a2, the third continuous portion 92a3, and the fourth continuous portion 92a4. In other words, two heat absorption members 70 aligned along the axial direction overlap the secondary battery 40 in FIG. 8 , with the second sides S2 of the flange portions 92 facing each other and the first sides S1 of the flange portions 92 facing opposite each other. Furthermore, the space between the two heat absorption members 70 is located in the center of the secondary battery 40 in the axial direction.

[0086] Next, the operation of the battery pack 1 when one of the secondary batteries 40 generates abnormal heat will be described.

[0087] When the secondary battery 40 generates abnormal heat, the temperature of the outer casing 90 of the heat absorption member 70 that is in contact with the abnormally heated secondary battery 40 rises, and the second continuous portion 92a2, the third continuous portion 92a3, and the fourth continuous portion 92a4 shown in Figures 4, 5, and 6 melt.

[0088] As described above, in the cross-sectional shape of the heat absorption member 70 shown in Fig. 5, the entire first continuous portion 92a1 is located inside the metal continuous portion 92b. In other words, in the cross-sectional shape of the heat absorption member 70 shown in Fig. 5, the first continuous portion 92a1 is not exposed to the outside of the exterior body 90 when the flange portion 92 is viewed from the S1 side. Furthermore, the melting points of the first metal layer L1c and the second metal layer L2c (metal continuous portion 92b) are higher than the melting point of the inner resin continuous portion 92a. Therefore, the flange portion 92 does not tear from the first side S1 side.

[0089] 5 and 6 , part of the second continuous portion 92a2, part of the third continuous portion 92a3, and part of the fourth continuous portion 92a4 are exposed to the outside of the exterior body 90. Therefore, when the inner resin continuous portion 92a melts, the flange portion 92 splits open from the second side S2, the third side S3, and the fourth side S4.

[0090] 8 , distance D1 corresponds to the axial distance between the inner periphery of the second continuous portion 92a2 and the outer periphery of the portion of the second continuous portion 92a2 that is exposed to the outside of the exterior body 90. In FIG. 8 , distance D2 corresponds to the distance, perpendicular to the axial direction, between the inner periphery of the third continuous portion 92a3 and the outer periphery of the portion of the third continuous portion 92a3 that is exposed to the outside of the exterior body 90. In FIG. 8 , distance D3 corresponds to the distance, perpendicular to the axial direction, between the inner periphery of the fourth continuous portion 92a4 and the outer periphery of the portion of the fourth continuous portion 92a4 that is exposed to the outside of the exterior body 90. As described above, first distance D1 is shorter than second distance D2 and third distance D3.

[0091] Therefore, as described above, the portion of the flange 92 on the second side S2 side will rupture earlier than the portions on the third side S3 side and the fourth side S4 side. When the portion of the flange 92 on the second side S2 side ruptures, the heat-absorbing agent 80 will leak from the portion of the flange 92 on the second side S2 side.

[0092] 8 , the heat-absorbing agent 80 leaking from the portion of the flange portion 92 on the second side S2 side flows toward between the two heat-absorbing members 70, adheres to the axial center of the secondary battery 40, and absorbs the heat of the secondary battery 40. Next, the heat-absorbing agent 80 spreads along the outer circumferential surface of the secondary battery 40 and absorbs the heat of the secondary battery 40.

[0093] Furthermore, the flange portion 92 further splits at the portion on the third side S3 side and the portion on the fourth side S4 side, causing further leakage of the heat-absorbing agent 80. The leaked heat-absorbing agent 80 flows along the outer peripheral surface of the secondary battery 40 and absorbs heat from the secondary battery 40.

[0094] When the secondary battery 40 generates abnormal heat, the split valve 43b shown in FIG. 3 may open, causing relatively high-temperature gas to spray out from the hole 43a1. Furthermore, at this time, relatively high-temperature gas may spray out from the split battery thin-wall portion 42a. In this case, the temperature at both ends of the secondary battery 40 in the axial direction may be higher than the temperature at the center of the secondary battery 40. Even in this case, as described above, the first continuous portion 92a1 overlaps with the metal continuous portion 92b when the flange portion 92 is viewed from the first side S1, and is not exposed to the outside of the exterior body 90. Therefore, the portion of the flange portion 92 on the first side S1 side does not split open.

[0095] At this time, the area on the third side S3 or the area on the fourth side S4, which is closer to the high temperature part of the secondary battery 40, tears open. Subsequently, the area on the second side S2 tears open.

[0096] Therefore, even when the temperature at both ends of the secondary battery 40 in the axial direction is higher than the temperature at the center of the secondary battery 40, the heat-absorbing agent 80 absorbs the heat of the secondary battery 40 as described above.

[0097] If the portion of the flange portion 92 on the first side S1 side were to cleave earlier than the other portions, the leaked heat-absorbing agent 80 would flow in the axial direction toward both ends of the secondary battery 40. Therefore, compared to the case where the portion of the flange portion 92 on the second side S2 side cleaves earlier as described above, the contact area between the heat-absorbing agent 80 and the secondary battery 40 is smaller, and the heat of the secondary battery 40 is less likely to be absorbed.

[0098] In the battery pack 1 of this embodiment, as described above, when the temperature is high at the center of the secondary battery 40, the portion of the flange portion 92 on the second side S2 side will cleave early. Also, when the temperature is high at both ends of the secondary battery 40, the portion of the third side S3 or the portion of the fourth side S4 will cleave, followed by the portion of the second side S2. These factors can improve the heat absorption efficiency of the heat-absorbing agent 80 when the secondary battery 40 abnormally generates heat.

[0099] <Modification of First Embodiment> Next, a battery pack 1 according to a modification of the first embodiment of the present disclosure will be described, focusing mainly on the differences from the battery pack 1 of the first embodiment described above.

[0100] Fig. 9 is a perspective view of a heat-absorbing member 170 of a battery pack 1 according to a modified example of the first embodiment of the present disclosure. Fig. 10 is a partial cross-sectional view of a battery unit 30 according to a modified example of the first embodiment. Fig. 10 is a diagram showing the cross-sectional shape of the battery unit 30 when cut along a plane perpendicular to the Y direction.

[0101] The heat absorption member 170 according to this modification does not have the first protrusion 90a1 of the heat absorption member 70 according to the first embodiment. The outer surface of the first exterior part 190a of the heat absorption member 170 has a flat surface 190a2. The heat absorption member 170 has a second protrusion 190b1 of the second exterior part 190b.

[0102] 10 , the flat surface 190a2 and the control board 20 face each other, so that the heat absorption member 170 can be disposed between the two secondary batteries 40 and the control board 20. The housing portion 191 contacts the two secondary batteries 40. Furthermore, by overlapping the flat surfaces 190a2 of the first exterior portions 190a of the two heat absorption members 170, the heat absorption member 170 can be disposed surrounded by four secondary batteries 40, similar to the heat absorption member 70 of the first embodiment described above.

[0103] Furthermore, in the heat-absorbing member 170 of this modified example, similar to the heat-absorbing member 70 of the first embodiment, the portion of the flange portion 192 on the second side S2 side cleaves early when the secondary battery 40 generates abnormal heat. Therefore, similar to the battery pack 1 of the first embodiment, in the battery pack 1 of this modified example, the heat-absorbing efficiency of the heat-absorbing agent 80 can be improved when the secondary battery 40 generates abnormal heat.

[0104] The second continuous portion 92a2 may be located between the sixth imaginary line Li6 and the fourteenth imaginary line Li14 in the first direction W1 in the cross-sectional shape of the heat absorption member 70 shown in Fig. 5. The fourteenth imaginary line Li14 is a imaginary line that is located between the sixth imaginary point P6, which is the end point on the S2 side of the eleventh imaginary line Li11, and the second imaginary point P2 in the first direction W1 in the cross-sectional shape of the heat absorption member 70 shown in Fig. 5, and extends along the third direction W3. In this case, in the cross-sectional shape of the heat absorption member 70 shown in Fig. 5, the first inner resin layer L1a and the second inner resin layer L2a are not welded to each other in the portion of the flange portion 92 on the S2 side of the fourteenth imaginary line Li14 in the first direction W1, and the first inner resin layer L1a and the second inner resin layer L2a are not continuous with each other.

[0105] Furthermore, the third continuous portion 92a3 may be located between the seventh imaginary line Li7 and the fifteenth imaginary line Li15 in the second direction W2 in the cross-sectional shape of the heat absorption member 70 shown in Fig. 6. The fifteenth imaginary line Li15 is a imaginary line that extends along the third direction W3 and is located between the seventh imaginary point P7, which is the end point of the twelfth imaginary line Li12 on the S3 side in the second direction W2, and the third imaginary point P3 in the cross-sectional shape of the heat absorption member 70 shown in Fig. 6. In this case, in the cross-sectional shape of the heat absorption member 70 shown in Fig. 6, the first inner resin layer L1a and the second inner resin layer L2a are not welded to each other in the portion of the flange portion 92 on the S3 side of the fifteenth imaginary line Li15 in the second direction W2, and the first inner resin layer L1a and the second inner resin layer L2a are not continuous with each other.

[0106] Furthermore, the fourth continuous portion 92a4 may be located between the eighth imaginary line Li8 and the sixteenth imaginary line Li16 in the second direction W2 in the cross-sectional shape of the heat absorption member 70 shown in Fig. 6. The sixteenth imaginary line Li16 is a virtual line that extends along the third direction W3 and is located between the eighth imaginary point P8, which is the end point of the thirteenth imaginary line Li13 on the S4 side in the second direction W2, and the fourth imaginary point P4 in the cross-sectional shape of the heat absorption member 70 shown in Fig. 6. In this case, in the cross-sectional shape of the heat absorption member 70 shown in Fig. 6, the first inner resin layer L1a and the second inner resin layer L2a are not welded to each other in the portion of the flange portion 92 on the S4 side of the sixteenth imaginary line Li16 in the second direction W2, and the first inner resin layer L1a and the second inner resin layer L2a are not continuous with each other.

[0107] Second Embodiment Next, a battery pack 1 according to a second embodiment of the present disclosure will be described, focusing mainly on the differences from the first embodiment described above.

[0108] Fig. 11 is a perspective view of a set of heat-absorbing members C included in a battery pack 1 according to a second embodiment of the present disclosure. Fig. 12 is a plan view of the set of heat-absorbing members C shown in Fig. 11. The battery pack 1 according to the second embodiment includes a plurality of (e.g., three) sets of heat-absorbing members C. Each set of heat-absorbing members C integrally includes two heat-absorbing members 270 and a connecting portion 271.

[0109] The heat absorption member 270 has the same configuration as the heat absorption member 70 of the first embodiment described above. The heat absorption member 270 has an accommodation portion 291 and a flange portion 292. In one set of heat absorption members C, the two heat absorption members 270 are aligned along the longitudinal direction of the heat absorption member 270 with the second sides S2 of the flange portions 292 facing each other and the first sides S1 of the flange portions 292 facing in opposite directions.

[0110] FIG. 13 is a diagram illustrating the cross-sectional shape of a pair of heat absorption members C when cut along a plane along the thickness direction of the flange portions 292 of the heat absorption members 270, focusing mainly on the cross-sectional shape of the connecting portion 271. The connecting portion 271 connects the flange portions 292 of the two heat absorption members 270 on the second side S2 side (i.e., the second continuous portion 292a2 side). The connecting portion 271 also connects the second exterior portions 290b of the two heat absorption members 270. For ease of explanation, the cross-sectional shape illustrated in FIG. 13 includes a 17th imaginary line Li17 and an 18th imaginary line Li18. The 17th imaginary line Li17 is an imaginary line that extends along the third direction W3 in the cross-sectional shape illustrated in FIG. 13 and overlaps with the end surface St1 on the second side S2 side of the flange portion 292 of one of the two heat absorption members 270. The 17th imaginary line Li17 corresponds to the boundary line between one of the two heat absorption members 270 and the connecting portion 271. The 18th imaginary line Li18 is an imaginary line that extends along the third direction W3 in the cross-sectional shape shown in Figure 13 and overlaps with the end face St2 on the second side S2 side of the flange portion 292 of the other of the two heat absorption members 270. The 18th imaginary line Li18 corresponds to the boundary line between the other of the two heat absorption members 270 and the connecting portion 271.

[0111] The connecting portion 271 includes a first connecting resin layer L3a, a second connecting resin layer L3b, and a connecting metal layer L3c between the first connecting resin layer L3a and the second connecting resin layer L3b. In the cross-sectional shape of the connecting portion 271 shown in Fig. 13, the first connecting resin layer L3a, the connecting metal layer L3c, and the second connecting resin layer L3b are stacked in this order.

[0112] The first connecting resin layer L3a connects the second inner resin layers L2a of the second exterior portions 290b of the two heat absorption members 270 to each other. The first connecting resin layer L3a is continuous with and integral to the second inner resin layers L2a of the two heat absorption members 270. The second connecting resin layer L3b connects the second outer resin layers L2b of the second exterior portions 290b of the two heat absorption members 270 to each other. The second connecting resin layer L3b is continuous with and integral to the second outer resin layers L2b of the two heat absorption members 270. The connecting metal layer L3c connects the second metal layers L2c of the second exterior portions 290b of the two heat absorption members 270 to each other. The connecting metal layer L3c is continuous with and integral to the second metal layers L2c of the two heat absorption members 270. The connecting portion 271 may connect the first exterior portions 290 a of the two heat-absorbing members 270 together.

[0113] 11 and 12, each heat absorption member C has an opening 272. The opening 272 is located between the two heat absorption members 270 at the second side S2 side of the flange portion 292 (i.e., the second continuous portion 292a2 side).

[0114] Next, the manufacturing process of one set of heat absorbing members C will be described.

[0115] 14 is a perspective view showing the exterior body 270c of one heat-absorbing member C before the heat-absorbing agent 80 is placed therein. In the exterior body 270c of one heat-absorbing member C, the first exterior portion 290a and the second exterior portion 290b of the two heat-absorbing members 270 and the connecting portion 271 are integrated together. In the exterior body 270c, the first inner resin layer L1a and the second inner resin layer L2a do not face each other.

[0116] As described above, the connecting portion 271 connects the second exterior portions 290b of the two heat-absorbing members 270. The first and second convex portions 290a1 and 290b1 of the two heat-absorbing members 270 and the openings 272 are formed by, for example, press working. That is, before the heat-absorbing agent 80 is accommodated, the exterior body 270c is formed by press working a single sheet member.

[0117] The outer casing 270c is subjected to the above-described injection process, bending process, and welding process, whereby a set of heat-absorbing members C is completed.

[0118] Next, the arrangement of the heat absorbing member 270 will be described.

[0119] Similar to the heat absorption members 270 of the first embodiment, each set of heat absorption members C is surrounded by four secondary batteries 40. As shown in Fig. 12, each set of heat absorption members C is arranged such that the two heat absorption members 270 are aligned along the axial direction.

[0120] In each of the two heat absorption members 270, the portion of the flange portion 292 on the first side S1 side is closer to the end of the secondary battery 40 in the axial direction than the portion on the second side S2 side. The opening 272 is located in the center of the secondary battery 40 in the axial direction.

[0121] Next, the operation of the battery pack 1 when one of the secondary batteries 40 generates abnormal heat will be described.

[0122] When one secondary battery 40 generates abnormal heat, in a set of heat absorption members C that are in contact with one secondary battery 40, the flange portions 292 of the two heat absorption members 270 first cleave at the portion on the second side S2, similar to the heat absorption member 70 of the first embodiment described above, and the heat absorption agent 80 leaks from the portion on the second side S2.

[0123] The heat-absorbing agent 80 leaking from the portion of the flange portion 292 on the second side S2 side flows through the opening 272, adheres to the axial center of the secondary battery 40, and absorbs heat from the secondary battery 40. The heat-absorbing agent 80 then spreads along the outer circumferential surface of the secondary battery 40, absorbing heat from the secondary battery 40.

[0124] Furthermore, similar to the heat-absorbing member 70 of the first embodiment, the flange portion 292 further splits at the portion on the third side S3 side and the portion on the fourth side S4 side, causing further leakage of the heat-absorbing agent 80. The leaked heat-absorbing agent 80 flows along the outer peripheral surface of the secondary battery 40 and absorbs heat from the secondary battery 40.

[0125] Therefore, in the battery pack 1 of the second embodiment, similarly to the battery pack 1 of the first embodiment, the heat absorbing efficiency of the heat absorbing agent 80 can be improved when the secondary battery 40 generates abnormal heat.

[0126] The above-described embodiments and modifications are intended to facilitate understanding of the present disclosure and are not intended to limit the present disclosure. The present disclosure may be modified or improved without departing from the spirit thereof, and equivalents thereof are also included in the present disclosure.

[0127] <Configuration Example of the Present Disclosure> The present disclosure may be implemented with the following combination of configurations.

[0128] (1) A heat-absorbing member comprising: a plurality of cylindrical secondary batteries; and an exterior body accommodating a heat-absorbing agent and the heat-absorbing agent, wherein the exterior body comprises: a first exterior part having a first resin layer and a first metal layer overlapping the first resin layer; and a second exterior part having a second resin layer facing the first resin layer and a second metal layer overlapping the second resin layer; the exterior body integrally comprises: an accommodating section accommodating the heat-absorbing agent between the first resin layer and the second resin layer; and a flange part in which the first resin layer and the second resin layer overlap all around the periphery of the accommodating section; the flange part having a continuous part in which the first resin layer and the second resin layer are continuous all around the periphery of the accommodating section; the continuous part having a first portion and a second portion; and the first portion being located inside at least one of the first metal layer and the second metal layer in a cross section of the heat-absorbing member when cut along a plane along the thickness direction of the flange part. the second portion has a portion exposed to the outside of the exterior body in a cross-sectional shape of the heat absorption member when cut along a plane along the thickness direction of the flange portion, and the heat absorption member is arranged in an axial direction in which a central axis of the secondary battery extends, with the first portion closer to an end of the secondary battery than the second portion.

[0129] (2) The battery pack according to (1), further comprising two heat-absorbing members, the two heat-absorbing members being aligned along the axial direction and spaced apart from each other.

[0130] (3) The battery pack according to (1) or (2), wherein the space between the two heat-absorbing members is located at a center of the secondary battery in the axial direction.

[0131] (4) The battery pack according to any one of (1) to (3), further comprising: two heat-absorbing members; and a set of heat-absorbing members each having a connecting portion that connects the flange portions of the two heat-absorbing members at the second portion side, wherein the set of heat-absorbing members has an opening between the flange portions of the two heat-absorbing members at the second portion side.

[0132] (5) The battery pack according to (4), wherein the opening is located at a center of the secondary battery in the axial direction.

[0133] (6) The battery pack according to any one of (1) to (5), wherein the second portion has a first second portion that is on the opposite side of the first portion in the axial direction from the first portion, and a second second portion that is closer to an end of the secondary battery than the first second portion, and when the heat absorption member is viewed along a direction perpendicular to the axial direction, the distance along the axial direction between the inner periphery of the first second portion and the outer periphery of the portion exposed to the outside of the first second portion is shorter than the distance along the direction perpendicular to the axial direction between the inner periphery of the second second portion and the outer periphery of the portion exposed to the outside of the second second portion.

[0134] REFERENCE SIGNS LIST 1 Battery pack 40 Secondary battery 70 Heat absorption member 80 Heat absorption agent 90 Exterior body 91 Storage section 92 Flange section 92a Inner resin continuous section (continuous section) 92a1 First continuous section (first section) 92a2 Second continuous section (second section, first second section) 92a3 Third continuous section (second section, second second section) 92a4 Fourth continuous section (second section, second second section) 271 Connecting section 272 Opening C One set of heat absorption members CL Central axis L1a First inner resin layer (first resin layer) L1c First metal layer L2a Second inner resin layer (second resin layer) L2c Second metal layer S1 First side S2 Second side S3 Third side S4 Fourth side

Claims

1. A heat absorbing member comprising: a plurality of cylindrical secondary batteries; and an exterior body that contains a heat absorbing agent and the heat absorbing agent, wherein the exterior body comprises: a first exterior part having a first resin layer and a first metal layer overlapping the first resin layer; and a second exterior part having a second resin layer facing the first resin layer and a second metal layer overlapping the second resin layer, the exterior body integrally comprising: a storage part that contains the heat absorbing agent between the first resin layer and the second resin layer; and a flange part in which the first resin layer and the second resin layer overlap all around the storage part, the flange part having a continuous part in which the first resin layer and the second resin layer are continuous all around the storage part, the continuous part having a first portion and a second portion, the first portion being located inside at least one of the first metal layer and the second metal layer in a cross-sectional shape of the heat absorbing member when cut along a plane along the thickness direction of the flange part, the second portion has a portion exposed to the outside of the exterior body in a cross-sectional shape of the heat absorption member when cut along a plane along the thickness direction of the flange portion, and the heat absorption member is arranged such that the first portion is closer to an end of the secondary battery than the second portion in an axial direction in which a central axis of the secondary battery extends.

2. The battery pack according to claim 1, comprising two of the heat absorbing members, the two heat absorbing members being aligned along the axial direction and spaced apart from each other.

3. The battery pack according to claim 1 or 2, wherein the space between the two heat absorbing members is located in the center of the secondary battery in the axial direction.

4. A battery pack as claimed in any one of claims 1 to 3, comprising two of the heat absorption members and a set of heat absorption members having integral connecting portions that connect the portions of the flange portions of the two heat absorption members on the second portion side, the set of heat absorption members having an opening between the portions of the flange portions of the two heat absorption members on the second portion side.

5. The battery pack according to claim 4, wherein the opening is located in the center of the secondary battery in the axial direction.

6. A battery pack as claimed in any one of claims 1 to 5, wherein the second portion has a first second portion which is a portion on the opposite side to the first portion in the axial direction, and a second second portion which is closer to an end of the secondary battery than the first second portion, and when the heat absorption member is viewed along a direction perpendicular to the axial direction, the distance along the axial direction between the inner periphery of the first second portion and the outer periphery of the portion exposed to the outside of the first second portion is shorter than the distance along the direction perpendicular to the axial direction between the inner periphery of the second second portion and the outer periphery of the portion exposed to the outside of the second second portion.

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