Battery pack

Abstract

This battery pack has improved waterproofing and heat dissipation properties. The battery pack comprises: a secondary battery; an outer case which houses the secondary battery; a lead plate which is electrically connected to a terminal of the secondary battery; a first member which surrounds a connection part where the terminal and the lead plate are connected, which is sandwiched between the secondary battery and the lead plate at the periphery the connection part, and which has waterproofing properties; and a second member which is in contact with the lead plate and the outer case, and which has heat dissipation properties.

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a battery unit including a plurality of battery blocks each composed of a plurality of batteries, a battery holder for holding the plurality of batteries, a metal plate attached to the battery holder and electrically connected to the terminals of the batteries, a housing for accommodating the plurality of battery blocks, and a cushioning material with heat dissipation properties that is arranged between the battery blocks and the housing.

[0003] Patent Document 2 discloses a battery pack including a plurality of battery cells, a battery holder that holds the plurality of battery cells, and a housing that houses the plurality of battery cells and the battery holder. The battery pack also includes a first lead plate electrically connected to a first end of the battery cell, a first inner waterproof sheet between the battery cell and the first lead plate, and a first outer waterproof sheet between the first lead plate and the battery holder. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-253641 [Patent Document 2] Japanese Patent Publication No. 2020-87874 Summary of the Invention [Problem to be solved by the invention]

[0005] The battery unit of Patent Document 1 does not have a waterproof function, and there is a risk that water may seep into the battery terminals. Also, the battery pack of Patent Document 2 has a waterproof function, but the first outer waterproof sheet prevents the heat of the battery cells from being transferred from the battery holder to the housing, and there is a risk that the heat of the battery cells may not be sufficiently released to the outside of the battery pack.

[0006] The present disclosure has been made in view of the above, and aims to improve waterproofing and heat dissipation in a battery pack. [Means for solving the problem]

[0007] The battery pack of the present disclosure includes a secondary battery, an exterior case that houses the secondary battery, lead plates that are electrically connected to terminals of the secondary battery, a waterproof first member that surrounds a connection portion where the terminals and the lead plates are connected and is sandwiched between the secondary battery and the lead plates around the connection portion, and a heat-dissipating second member that is in contact with the lead plates and the exterior case. The secondary battery has an insulating member surrounding the connected portion of the terminal to which the lead plate is connected, and the first member is sandwiched between the insulating member and the lead plate. . [Effects of the Invention]

[0008] According to the present disclosure, it is possible to improve waterproofing and heat dissipation in a battery pack. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view of a battery pack according to a first embodiment. [Figure 2] FIG. 2 is an exploded perspective view of the battery pack according to the first embodiment. [Figure 3] FIG. 3 is an enlarged vertical cross-sectional view of the positive terminal side of the secondary battery in the battery pack according to the first embodiment. [Figure 4] FIG. 4 is an enlarged vertical cross-sectional view of the negative terminal side of the secondary battery in the battery pack according to the first embodiment. [Figure 5] FIG. 5 is an exploded perspective view of a battery pack according to the second embodiment. [Figure 6] FIG. 6 is an enlarged vertical cross-sectional view of the positive terminal side of the battery unit with the sheet set arranged. [Figure 7] FIG. 7 is an enlarged vertical cross-sectional view of the positive terminal side of the secondary battery in the battery pack according to the second embodiment. [Figure 8] FIG. 8 is an enlarged vertical cross-sectional view of the negative terminal side of the secondary battery in the battery pack according to the second embodiment. [Figure 9] FIG. 9 is an enlarged vertical cross-sectional view of the positive terminal side of the secondary battery in the battery pack according to the third embodiment. [Figure 10] FIG. 10 is an enlarged vertical cross-sectional view of the positive terminal side of the secondary battery in the battery pack according to the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] The following describes embodiments in detail with reference to the drawings. However, 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. From the second embodiment onwards, a description of matters common to the first embodiment will be omitted, and only the differences will be described. In particular, similar effects resulting from similar configurations will not be mentioned in each embodiment.

[0011] First Embodiment Fig. 1 is a perspective view of a battery pack according to the first embodiment, and Fig. 2 is an exploded perspective view of the battery pack according to the first embodiment.

[0012] The battery pack 1 can be used as a power source for electronic devices, electric vehicles, power tools, etc. The battery pack 1 includes an exterior case 10 and a battery unit 20, as shown in FIG.

[0013] The exterior case 10 is box-shaped and houses the battery unit 20. The exterior case 10 has a first case portion 11 and a second case portion 12. As shown in FIG. 2 , the battery unit 20 includes a plurality of secondary batteries 30, a holder 40, lead plates 50, a first member 60, and a second member 70.

[0014] The secondary batteries 30 are, for example, lithium ion batteries. The secondary batteries 30 are cylindrical. The multiple secondary batteries 30 are arranged such that the orientations of the positive electrode terminals 30a and the negative electrode terminals 30b of adjacent secondary batteries 30 are different from each other. It goes without saying that the arrangement of the multiple secondary batteries 30 is not limited to this arrangement.

[0015] Fig. 3 is an enlarged vertical cross-sectional view of the positive electrode terminal side of the secondary battery in the battery pack according to the first embodiment. Fig. 4 is an enlarged vertical cross-sectional view of the negative electrode terminal side of the secondary battery in the battery pack according to the first embodiment. The secondary battery 30 includes an electrode assembly 31, a can 32, a lid 33, a first insulating member 34, and a second insulating member 35.

[0016] The electrode assembly 31 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.

[0017] As shown in Fig. 3, the can 32 is cylindrical and has an opening 32a at one end. The can 32 is electrically conductive and is electrically connected to the negative electrode of the electrode assembly 31. The lid 33 is plate-shaped and covers the opening 32a of the can 32 from the inside of the can 32, and has a protrusion 33a in the center. The lid 33 is electrically conductive and is electrically connected to the positive electrode of the electrode assembly 31. The can 32 and the lid 33 are made of, for example, iron, SUS, or aluminum.

[0018] The first insulating member 34 electrically insulates the can 32 from the lid 33. The first insulating member 34 is made of, for example, an elastic rubber having electrical insulation properties. The first insulating member 34 is, for example, an annular member with an L-shaped cross section, and is sandwiched between the peripheral edge of the lid 33 and the peripheral edge of the opening 32a of the can 32.

[0019] The outer portion of the lid 33 surrounded by the first insulating member 34, that is, the exposed portion of the lid 33, constitutes the positive electrode terminal 30a of the secondary battery 30.

[0020] The second insulating member 35 is a member for providing an insulating portion on the outer peripheral surface of the can 32. The second insulating member 35 is, for example, a polyimide film, and covers the outer peripheral surface of the can 32. As shown in FIG. 4 , the second insulating member 35 has an opening 35a on the end face of the can 32 opposite the lid 33.

[0021] The portion of the outer surface of the can 32 that is surrounded by the opening 35a of the second insulating member 35, i.e., the portion of the outer surface of the can 32 that is exposed on the side opposite the lid 33, forms the negative terminal 30b of the secondary battery 30.

[0022] As shown in Fig. 2, the holder 40 holds the peripheral side surfaces of the multiple secondary batteries 30. The holder 40 has multiple cylindrical holding portions 41 that are open at both ends. The holder 40 does not hold the end faces of the multiple secondary batteries 30. Furthermore, the holder 40 is not interposed between the end faces of the multiple secondary batteries 30 and the exterior case 10. The holder 40 is made of an electrically insulating resin such as polypropylene.

[0023] The lead plates 50 are electrically connected to the terminals of the secondary batteries 30. Specifically, the battery pack 1 has a plurality of lead plates 50, and the plurality of lead plates 50 are electrically connected to the positive terminal 30a and the negative terminal 30b of the secondary batteries 30 so that the plurality of secondary batteries 30 are electrically connected in series or in parallel.

[0024] The lead plate 50 has an embossed portion 51. The embossed portion 51 is formed in advance, for example, by pressing before being connected to the positive electrode terminal 30a or the negative electrode terminal 30b. The embossed portion 51 is concave and has an end surface 51a and a tapered surface 51b around the end surface 51a, as shown in FIGS. 3 and 4 .

[0025] An end surface 51a of the embossed portion 51 comes into contact with the positive terminal 30a or the negative terminal 30b and is electrically connected thereto. Specifically, as shown in Fig. 3, the end surface 51a of the embossed portion 51 comes into contact with the protruding end surface 33b of the convex portion 33a of the positive terminal 30a and is electrically connected thereto. The protruding end surface 33b is a connected portion H1 of the positive terminal 30a that is electrically connected to the lead plate 50.

[0026] 4, the end surface 51a of the embossed portion 51 is electrically connected to the center of the negative terminal 30b. The center of the negative terminal 30b is a connection portion H2 of the negative terminal 30b that is electrically connected to the lead plate 50.

[0027] The tapered surface 51b is inclined so that the width of the embossed portion 51 becomes smaller from the base end of the embossed portion 51 toward the end surface 51a.

[0028] The first member 60 surrounds the connection between the terminal of the secondary battery 30 and the lead plate 50, is sandwiched between the secondary battery 30 and the lead plate 50 around the connection, and is waterproof. The first member 60 is annular as shown in FIG. 2 and is made of, for example, elastic rubber. The battery pack 1 has multiple first members 60, and the multiple first members 60 are arranged between the positive terminal 30a of the secondary battery 30 and the lead plate 50, and between the negative terminal 30b and the lead plate 50, respectively.

[0029] As shown in FIG. 3, the first member 60 is disposed so as to surround the connection portion C1 between the lead plate 50 and the positive terminal 30a. The connection portion C1 is the portion where the end surface 51a of the embossed portion 51 and the protruding end surface 33b of the convex portion 33a are in contact. Specifically, the first member 60 surrounds the convex portion 33a. The first member 60 is also sandwiched between the tapered surface 51b of the embossed portion 51 and the outer surface of the first insulating member 34 of the secondary battery 30.

[0030] To fully exhibit its waterproofing function, the first member 60 is compressed by the tapered surface 51b of the embossed portion 51 and the outer surface of the first insulating member 34 of the secondary battery 30. Because the positive terminal 30a is surrounded by the first insulating member 34, even if water seeps into the exterior case 10, the seeping water will not reach the positive terminal 30a. This makes the positive terminal 30a waterproof.

[0031] 4, the first member 60 is disposed so as to surround the connection portion C2 between the lead plate 50 and the negative terminal 30b. The connection portion C2 is the portion where the end surface 51a of the embossed portion 51 contacts the center portion of the negative terminal 30b. The first member 60 is sandwiched between the tapered surface 51b of the embossed portion 51 and the outer surface of the second insulating member 35 of the secondary battery 30.

[0032] The first member 60 is compressed by the tapered surface 51b of the embossed portion 51 and the outer surface of the second insulating member 35 of the secondary battery 30 to fully exhibit its waterproofing function. Because the negative terminal 30b is surrounded by the second insulating member 35, even if water penetrates into the exterior case 10, the penetrated water will not reach the negative terminal 30b. This makes the negative terminal 30b waterproof. This improves the waterproofing of the battery pack 1.

[0033] The second member 70 is in contact with the lead plate 50 and the outer case 10 and has heat dissipation properties. As shown in FIG. 2, the second member 70 is in the form of a rectangular sheet in a plan view, and is made of, for example, silicon. Specifically, as shown in FIGS. 3 and 4, one sheet surface of the second member 70 is in contact with the plate surface of the lead plate 50. The other sheet surface of the second member 70 is in contact with the inner surface of the outer case 10. In other words, the second member 70 is sandwiched between the plate surface of the lead plate 50 and the inner surface of the outer case 10. The second member 70 may be compressed by the plate surface of the lead plate 50 and the inner surface of the outer case 10 to provide waterproofing.

[0034] Heat from the secondary battery 30 is transferred from the positive terminal 30a through the lead plate 50 and the second member 70 to the exterior case 10 and is then released to the outside of the battery pack 1. Heat from the secondary battery 30 is transferred from the negative terminal 30b through the lead plate 50 and the second member 70 to the exterior case 10 and is then released to the outside of the battery pack 1.

[0035] In this way, the heat transfer path through which the heat of the secondary battery 30 is transferred to the exterior case 10 is made up of the lead plate 50, the second member 70, and the exterior case 10. Therefore, the heat of the secondary battery 30 can be released more efficiently than when other members such as the holder 40 are included in the heat transfer path. This improves the heat dissipation performance of the battery pack 1.

[0036] The battery pack 1 also includes an external connection terminal (not shown) that is electrically connected to the lead plate 50 and enables charging and discharging of the secondary battery 30, and a control board (not shown) that controls charging and discharging of the secondary battery 30.

[0037] Next, we will explain the assembly process of the battery pack 1. First, the battery unit 20 is assembled. First, multiple secondary batteries 30 are attached to the holder 40. Next, the first member 60 is attached to the multiple secondary batteries 30 using an adhesive or the like, and further, the lead plate 50 is attached to the first member 60 using an adhesive or the like.

[0038] In this state, the connection portion H1 of the positive electrode terminal 30a and the connection portion H2 of the negative electrode terminal 30b are resistance-welded to the end face 51a of the embossed portion 51. The resistance welding is performed by pressing a pair of electrodes against the surface of the embossed portion 51 opposite the end face 51a. As a result, the first member 60 is compressed by the secondary battery 30 and the lead plate 50.

[0039] Furthermore, the second member 70 is attached to the lead plate 50 using adhesive or the like, and the battery unit 20 is now completed.

[0040] Next, the battery unit 20 is connected to the external connection terminal and the control board, and inserted into the first case part 11. Furthermore, the second case part 12 is attached to the first case part 11. At this time, the second member 70 is sandwiched between the lead plate 50 and the outer case 10. In this way, the battery pack 1 is completed.

[0041] Second Embodiment Next, a battery pack according to a second embodiment will be described, mainly focusing on the differences from the first embodiment. Fig. 5 is an exploded perspective view of the battery pack according to the second embodiment.

[0042] The first member 160 of the second embodiment is a rectangular sheet in plan view and has a plurality of first holes 161. The first holes 161 are large enough to surround the connection portions C1 and C2. Specifically, when the first member 160 is sandwiched between the secondary battery 30 and the lead plate 150, the periphery of the first holes 161 surrounds the connected portions H1 and H2, i.e., the connection portions C1 and C2, in plan view.

[0043] The lead plate 150 of the second embodiment is flat and does not have any pre-formed embossed portions. The second member 170 of the second embodiment has a plurality of second holes 171. The second holes 171 are large enough to allow a pair of electrodes E used in resistance welding to pass through, and when the second member 170 is sandwiched between the lead plate 150 and the outer case 10, the periphery of the second holes 171 surrounds the connected portions H1 and H2, i.e., the connecting portions C1 and C2, in a plan view.

[0044] Next, the steps for assembling the battery pack 1 of the second embodiment will be described, focusing on the differences from the first embodiment.

[0045] In the assembly process of the battery pack 1 of the second embodiment, before the first member 160 and the lead-plate 150 are attached to the secondary battery 30, the lead-plate 150, the first member 160, and the second member 170 are attached using an adhesive or the like so that the first hole 161 and the second hole 171 overlap in a plan view. In this way, a set of the lead-plate 150, the first member 160, and the second member 170 (hereinafter referred to as a sheet set) is assembled.

[0046] Next, the set of sheets is arranged on the multiple secondary batteries 30 so that the multiple first holes 161 of the first member 160 surround the connection portion H1 of the positive terminal 30a and the connection portion H2 of the negative terminal 30b, respectively. In this way, the lead plate 150, the first member 160, and the second member 170 are arranged on the positive terminal 30a and the negative terminal 30b in an assembled state, so the number of assembly steps can be reduced compared to when the lead plate 150, the first member 160, and the second member 170 are arranged separately as in the first embodiment.

[0047] 6 is an enlarged vertical cross-sectional view of the positive terminal side of the battery unit with the sheet set in place. With the sheet set in place, the lead plate 150 and the positive terminal 30a are not in contact. Resistance welding is performed in this state. Specifically, the tips of a pair of rod-shaped electrodes E contact the lead plate 150 through the second hole 171, and the pair of electrodes E press the lead plate 150 toward the connection portion H1 (i.e., the protruding end surface 33b).

[0048] 7 is an enlarged vertical cross-sectional view of the positive terminal side of a secondary battery 30 in a battery pack according to the second embodiment. When the lead plate 150 is pressed by the pair of electrodes E, the lead plate 150 is deformed, and an embossed portion 151 having an end face 151a and a tapered surface 151b is formed on the lead plate 150. The end face 151a of the embossed portion 151 and the protruding end face 33b of the protrusion 33a of the positive terminal 30a (i.e., the connected portion H1) come into contact with each other and are welded together. This electrically connects the lead plate 150 to the positive terminal 30a.

[0049] The first member 160 is sandwiched and compressed at the periphery of the first hole 161 between the tapered surface 151b of the embossed portion 151 and the outer surface of the first insulating member 34. This makes it possible to waterproof the positive terminal 30a. Furthermore, because the embossed portion 151 in the second embodiment is formed during welding, it is not necessary to perform the steps of preforming the embossed portion 151 on the lead plate 150 and positioning the embossed portion 151 and the positive terminal 30a, as compared to the first embodiment, in which the embossed portion 151 is preformed before welding. This reduces the number of steps required to assemble the battery pack 1.

[0050] Furthermore, because the second member 170 is attached to the lead plate 150 before resistance welding, the periphery of the second hole 171 deforms to follow the deformation of the lead plate 150 due to resistance welding, and is in contact with the lead plate 150. That is, the periphery of the second hole 171 is in contact with the embossed portion 151. Specifically, the periphery of the second hole 171 is in contact with the embossed portion 151 around the end face 151a of the embossed portion 151. Therefore, the second member 170 can transfer heat from the secondary battery 30 to the exterior case 10 more efficiently than when the second member 170 is separated from the embossed portion 151 as in the first embodiment.

[0051] 8 is an enlarged vertical cross-sectional view of the negative terminal side of the secondary battery in the battery pack according to the second embodiment. On the negative terminal 30b side, the lead plate 150 is also deformed by being pressed by a pair of electrodes E during resistance welding, and an embossed portion 151 having an end surface 151a and a tapered surface 151b is formed on the lead plate 150. The end surface 151a of the embossed portion 151 contacts and is welded to the central portion of the negative terminal 30b (i.e., the connection portion H2). This electrically connects the lead plate 150 to the negative terminal 30b.

[0052] The first member 160 is sandwiched and compressed at the periphery of the first hole 161 between the tapered surface 151b of the embossed portion 151 and the outer surface of the second insulating member 35. This makes it possible to waterproof the negative electrode terminal 30b.

[0053] <Third embodiment> Next, a battery pack 1 according to a third embodiment will be described, mainly focusing on the differences from the second embodiment. Fig. 9 is an enlarged vertical cross-sectional view of the positive terminal 30a side of the secondary battery 30 in the battery pack according to the third embodiment.

[0054] The second member 270 of the third embodiment is shaped to contact the lead plate 150 and the outer case 10 at positions overlapping the connection portions C1 and C2 in a plan view. Specifically, the second member 270 has multiple protrusions 271 that protrude toward the secondary battery 30. The second member 270 does not have a second hole 171.

[0055] The protruding portion 271 is located at a position where the protruding end surface 271a contacts the surface of the embossed portion 151 opposite the end surface 151a. The sheet surface of the second member 270 opposite the protruding portion 271 contacts the inner surface of the outer case 10. That is, in the third embodiment, the embossed portion 151 and the outer case 10 are connected via the protruding portion 271.

[0056] On the positive electrode terminal 30a side of the secondary battery 30, heat of the secondary battery 30 is transferred from the positive electrode terminal 30a to the exterior case 10 via the embossed portion 151 of the lead plate 150 and the protrusion 271 of the second member 270. On the other hand, on the negative electrode terminal 30b side of the secondary battery 30, heat of the secondary battery 30 is transferred from the negative electrode terminal 30b to the exterior case 10 via the embossed portion 151 of the lead plate 150 and the protrusion 271 of the second member 270. Therefore, the length of the heat transfer path along which heat of the secondary battery 30 is transferred to the exterior case 10 is shorter than in the first and second embodiments when the second members 70, 170 do not have the protrusion 271.

[0057] Furthermore, the volume of the space between the embossed portion 151 and the exterior case 10 in the third embodiment is smaller than that in the first and second embodiments because the protrusion 271 is located in that space. Therefore, the second member 270 in the third embodiment can transfer heat from the secondary battery 30 more efficiently than in the first and second embodiments, where the second members 70 and 170 do not have the protrusion 271.

[0058] In the third embodiment, the second member 270 is attached to the lead plate 150 after the lead plate 150 is resistance-welded to the positive electrode terminal 30a and the negative electrode terminal 30b.

[0059] <Fourth embodiment> Next, the battery pack 1 according to the fourth embodiment will be described, mainly focusing on the differences from the second embodiment. Fig. 10 is an enlarged vertical cross-sectional view of the positive terminal side of the secondary battery 30 in the battery pack according to the fourth embodiment. The battery pack 1 according to the fourth embodiment further includes a waterproof material S1 and a waterproof material S2.

[0060] The waterproof material S1 and the waterproof material S2 are, for example, silicone-based waterproof materials. On the positive electrode terminal 30a side of the secondary battery 30, the waterproof material S1 and the waterproof material S2 are filled between the secondary battery 30 and the lead plate 150 around the area where the first member 160 is clamped. Specifically, the waterproof material S1 is filled between the secondary battery 30 and the lead plate 150, radially outward of the secondary battery 30 from the area where the first member 160 and the first insulating member 34 contact each other. The waterproof material S2 is filled between the secondary battery 30 and the lead plate 150, radially inward of the area where the first member 160 and the first insulating member 34 contact each other, and radially outward of the secondary battery 30 from the connected portion H1.

[0061] The positive electrode terminal 30a can be more reliably waterproofed by the waterproof material S1 and the waterproof material S2. The battery pack 1 may be provided with either the waterproof material S1 or the waterproof material S2.

[0062] On the other hand, on the negative electrode terminal 30b side of the secondary battery 30, the waterproof material S1 is filled between the secondary battery 30 and the lead plate 150, radially outward of the secondary battery 30 from the contact point between the first member 160 and the second insulating member 35. The waterproof material S2 is filled radially inward of the secondary battery 30 from the contact point between the first member 160 and the second insulating member 35, and radially outward of the secondary battery 30 from the connected portion H2. The waterproof material S1 and the waterproof material S2 can more reliably waterproof the negative electrode terminal 30b.

[0063] In the assembly process of the battery unit 20, the waterproofing material S1 and the waterproofing material S2 are applied around the connection portion H1 of the positive electrode terminal 30a and the connection portion H2 of the negative electrode terminal 30b before the first member 160 is attached to the secondary battery 30. Next, the first member 160 and the lead plate 150 are attached to the secondary battery 30, and the positive electrode terminal 30a and the negative electrode terminal 30b are resistance-welded to the lead plate 150, so that the waterproofing material S1 and the waterproofing material S2 are filled in the above positions. Note that the waterproofing material S1 may be applied from the periphery where the first member 160 is clamped after the positive electrode terminal 30a and the negative electrode terminal 30b are resistance-welded to the lead plate 150.

[0064] The battery pack 1 according to the fourth embodiment does not necessarily have to include the second member 170. In this case, the plate surface of the lead plate 150 comes into contact with the inner surface of the exterior case .

[0065] The above-described embodiments 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. [Explanation of symbols]

[0066] 1 battery pack 10 Outer case 30 Secondary battery 30a Positive terminal (terminal) 30b Negative terminal (terminal) 34 First insulating member (insulating member) 35 Second insulating member (insulating member) 50 Reed plate 51,151 Embossed section 51a,151a End face 60 First member 70 Second member 171 2nd hole (hole) 271 Protrusion C1, C2 connection part H1,H2 Connected part S1,S2 Waterproof material

Claims

1. A secondary battery; an exterior case that houses the secondary battery; a lead plate electrically connected to a terminal of the secondary battery; a waterproof first member that surrounds a connection portion where the terminal and the lead plate are connected and is sandwiched around the connection portion between the secondary battery and the lead plate; a second member that is in contact with the lead plate and the exterior case and has heat dissipation properties, the secondary battery has an insulating member surrounding a connection portion of the terminal to which the lead plate is connected, the first member is sandwiched between the insulating member and the lead plate; Battery pack.

2. the secondary battery is cylindrical, The battery further includes a holder that holds the peripheral side surface of the secondary battery and has open ends. The battery pack according to claim 1 .

3. the second member has a hole; The periphery of the hole surrounds the connection portion in a plan view. The battery pack according to claim 1 or 2.

4. The lead plate has a concave embossed portion, an end surface of the embossed portion constitutes the connection portion that connects to the terminal; The peripheral edge of the hole is in contact with the embossed portion around the end surface. The battery pack according to claim 3 .

5. the second member is shaped to contact the lead plates and the outer case at positions overlapping the connection portions in a plan view; The battery pack according to claim 1 or 2.

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