Battery cell and battery module

Abstract

A battery cell (100) comprises: a battery element (110); a lid material (120) at least partially covering the battery element (110); and an exterior film (140) having a winding portion (142) and a lead-out portion (144). The winding portion (142) is wound around the battery element (110) and the lid material (120). The lead-out portion (144) is pulled out from the winding portion (142) toward the opposite side to the side where the battery element (110) of the lid material (120) is located. The lead-out portion (144) is at least partially folded back toward the side where the battery element (110) is located.

Description

Battery cells and battery modules

[0001] The present invention relates to a battery cell and a battery module.

[0002] In recent years, various battery modules have been developed, each of which includes a plurality of battery cells.

[0003] Patent Document 1 describes a battery cell. The battery cell includes an electrode assembly, an exterior member wrapped around the electrode assembly, and a lid member fitted into each of the openings at both ends of the exterior member. The exterior member is joined to the surface of the lid member opposite the surface facing the electrode assembly.

[0004] Patent Document 2 describes a battery cell. The battery cell includes a laminated structure and an exterior member that seals the laminated structure. The exterior member has a lower film and an upper film located respectively below and above the battery cell. The joint portion of the peripheral edge of the laminated structure of the lower film and the upper film is folded back.

[0005] Patent Document 3 describes an electrochemical device. The electrochemical device includes an exterior body. The exterior body has a housing portion that houses an electrochemical element and a side adhesive portion having a folded portion.

[0006] International Publication No. 2021 / 157731 Japanese Patent Application Laid-Open No. 2008-41494 Japanese Patent Application Laid-Open No. 2002-245999

[0007] As described in Patent Document 1, an exterior film may be wrapped around a battery element and a lid material that at least partially covers the battery element. The exterior film may have a conductor such as a metal foil. A conductor such as a bus bar electrically connected to the battery cell may be present on the side of the lid material opposite to the side where the battery element is located. If such a conductor is present, it may be necessary to prevent a short circuit between the exterior film and the conductor.

[0008] One example of an object of the present invention is to prevent a short circuit between an exterior film and a conductor present on the opposite side of the lid material from the side on which the battery element is located. Other objects of the present invention will become apparent from the description of this specification.

[0009] One aspect of the present invention is as follows: 1. A battery cell comprising: a battery element; a lid material at least partially covering the battery element; and an exterior film having a first portion wrapped around the battery element and the lid material and a second portion pulled out from the first portion toward the side of the lid material opposite to the side where the battery element is located, wherein the second portion is at least partially folded back toward the side where the battery element is located. 2. The battery cell described in 1., wherein the lid material has a protrusion located on the side opposite to the side where the battery element is located, and the second portion at least partially covers the protrusion. 3. A battery module comprising: the battery cell described in 1. or 2.; and a bus bar electrically connected to the battery cell.

[0010] According to the above aspect of the present invention, it is possible to prevent a short circuit between the exterior film and the conductor present on the side of the lid member opposite to the side on which the battery element is located.

[0011] It is a perspective view of a battery cell according to an embodiment. It is a cross-sectional schematic view of a first imaginary plane α shown in Figure 1. It is a cross-sectional schematic view of a second imaginary plane β shown in Figure 1. It is a perspective view of a battery module according to an embodiment.

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, similar components are designated by similar reference numerals, and the description thereof will be omitted as appropriate.

[0013] Fig. 1 is a perspective view of a battery cell 100 according to an embodiment. Fig. 2 is a schematic cross-sectional view of a first imaginary plane α shown in Fig. 1. Fig. 3 is a schematic cross-sectional view of a second imaginary plane β shown in Fig. 1.

[0014] For the purpose of explanation, the X, Y, and Z directions are shown in each figure. The X direction indicates the front-rear direction of the battery cell 100. The Y direction is a direction perpendicular to the X direction. The Y direction indicates the left-right direction of the battery cell 100. The Z direction is a direction perpendicular to both the X and Y directions. The Z direction indicates the up-down direction of the battery cell 100. The arrows pointing to the X direction, the Y direction, and the Z direction indicate the rear, right, and up directions of the battery cell 100, respectively. In FIG. 2, the white circle with an X indicating the Y direction indicates that the arrow pointing to the Y direction extends from the front to the back of the page. In FIG. 3, the white circle with a black dot indicating the Z direction indicates that the arrow pointing to the Z direction extends from the back to the front of the page. The relationship between the X direction, Y direction, and Z direction and the front-rear direction, left-right direction, and up-down direction of the battery cell 100 is not limited to the example described in the embodiment.

[0015] Hereinafter, as needed, the side indicated by the arrow indicating the X direction will be referred to as the +X side, and the side opposite the side indicated by the arrow indicating the X direction will be referred to as the -X side. Hereinafter, as needed, the side indicated by the arrow indicating the Y direction will be referred to as the +Y side, and the side opposite the side indicated by the arrow indicating the Y direction will be referred to as the -Y side. Hereinafter, as needed, the side indicated by the arrow indicating the Z direction will be referred to as the +Z side, and the side opposite the side indicated by the arrow indicating the Z direction will be referred to as the -Z side.

[0016] 1 and 2 is a plane perpendicular to the Y direction at approximately the center in the Y direction of the battery cell 100 according to the embodiment. The second imaginary plane β shown in Fig. 1 and 3 is a plane perpendicular to the Z direction at approximately the center in the Z direction of the battery cell 100 according to the embodiment.

[0017] As shown in FIGS. 1 to 3, a battery cell 100 according to the embodiment includes a plurality of battery elements 110, a pair of lid members 120, a pair of conductors 130, and an exterior film 140.

[0018] As shown in FIG. 3 , the multiple battery elements 110 are stacked in the Y direction. Each battery element 110 has a positive electrode, a negative electrode, and a separator (not shown). As shown in FIGS. 1 to 3 , each battery element 110 has a substantially rectangular parallelepiped shape with a length in the X direction, a width in the Z direction, and a height in the Y direction. When viewed from the X direction, each battery element 110 has a substantially rectangular shape with a pair of short sides extending in the Y direction and a pair of long sides extending in the Z direction. As shown in FIGS. 2 and 3 , multiple positive electrode current collectors 112 extend from the multiple battery elements 110 toward the −X side. The positive electrodes and positive electrode current collectors 112 of the battery elements 110 are electrically connected to each other. As shown in FIGS. 2 and 3 , multiple negative electrode current collectors 114 extend from the multiple battery elements 110 toward the +X side. The negative electrodes and negative electrode current collectors 114 of the battery elements 110 are electrically connected to each other.

[0019] Hereinafter, the battery cell 100 will be described as having a plurality of battery elements 110. However, the number of battery elements 110 included in the battery cell 100 and the shape of each battery element 110 are not limited to the examples shown in Figures 1 to 3. The number of battery elements 110 included in the battery cell 100 may be one, two, three, five or more.

[0020] As shown in Figures 2 and 3, a pair of lid members 120 are located on both sides of the multiple battery elements 110 in the X direction. Each lid member 120 at least partially covers the multiple battery elements 110. Each lid member 120 is made of an insulator such as resin. Unless otherwise specified, the first lid member 120a and the second lid member 120b refer to the lid member 120 on the -X side and the lid member 120 on the +X side, respectively. The first lid member 120a has a first lid base material 122a, a first outer protrusion 124a, and a first inner protrusion 126a. The second lid member 120b has a second lid base material 122b, a second outer protrusion 124b, and a second inner protrusion 126b. The second cover base material 122b, the second outer protrusion 124b, and the second inner protrusion 126b correspond to the first cover base material 122a, the first outer protrusion 124a, and the first inner protrusion 126a, respectively.

[0021] The first lid member 120a will be described with reference to FIGS.

[0022] The first lid base material 122a has a generally plate shape perpendicular to the X direction. The first lid base material 122a covers the −X side end faces of the multiple battery elements 110. When viewed from the X direction, the first lid base material 122a has a generally rectangular shape with a pair of short sides extending in the Y direction and a pair of long sides extending in the Z direction.

[0023] The first external protrusion 124a is located on the opposite side of the first lid base material 122a from the side where the multiple battery elements 110 are located. The first external protrusion 124a protrudes toward the -X side from the entire circumference in the X direction of the -X side surface of the first lid base material 122a. However, the first external protrusion 124a does not have to be located all around the entire circumference in the X direction of the first lid base material 122a, but may be located only partially around the entire circumference in the X direction of the first lid base material 122a.

[0024] The first internal protrusion 126a is located on the side of the first lid base material 122a where the multiple battery elements 110 are located. The first internal protrusion 126a protrudes toward the +X side from the entire circumference in the X direction of the +X side surface of the first lid base material 122a. However, the first internal protrusion 126a may not be located all around the entire circumference in the X direction of the first lid base material 122a, but may be located partially around the entire circumference in the X direction of the first lid base material 122a.

[0025] The second lid member 120b may be similar to the first lid member 120a, except that the first lid member 120a and the second lid member 120b are arranged substantially symmetrically.

[0026] As shown in FIGS. 2 and 3 , a pair of conductors 130 are located on both sides of the multiple battery elements 110 in the X direction. Each conductor 130 and the multiple battery elements 110 are electrically connected to one another. Hereinafter, unless otherwise specified, the first conductor 130a and the second conductor 130b refer to the conductor 130 on the −X side and the conductor 130 on the +X side, respectively. The first conductor 130a has a first barrier layer 132a, a first external terminal 134a, and a first internal terminal 136a. The second conductor 130b has a second barrier layer 132b, a second external terminal 134b, and a second internal terminal 136b. The second barrier layer 132b, the second external terminal 134b, and the second internal terminal 136b correspond to the first barrier layer 132a, the first external terminal 134a, and the first internal terminal 136a, respectively.

[0027] The first conductor 130a will be described with reference to FIGS.

[0028] The first barrier layer 132a is a layer perpendicular to the X-direction. The first barrier layer 132a is, for example, a conductor such as a metal layer. The first lid substrate 122a and the first barrier layer 132a at least partially overlap each other in the X-direction. The first barrier layer 132a is at least partially positioned between the first lid substrate 122a and the plurality of battery elements 110. The water vapor transmission rate of the first barrier layer 132a is lower than that of the first lid substrate 122a. Therefore, the first barrier layer 132a can block the transmission of moisture from the first lid material 120a to the plurality of battery elements 110. The first internal protrusions 126a are at least partially positioned around the first barrier layer 132a in the X-direction. Therefore, the first barrier layer 132a can be positioned or held by the first internal protrusions 126a.

[0029] The first external terminal 134a is a conductor such as a metal block. The first external terminal 134a is located on the side of the first barrier layer 132a opposite to the side on which the multiple battery elements 110 are located. The first external terminal 134a is a protrusion that protrudes toward the −X side from approximately the center of the −X side surface of the first barrier layer 132a. However, the first external terminal 134a may protrude toward the −X side from a portion that is offset from the approximately center of the −X side surface of the first barrier layer 132a. The first external terminal 134a penetrates the first lid base material 122a in the X direction and is drawn out from the −X side surface of the first lid base material 122a toward the −X side. Therefore, as will be described later with reference to FIG. 4, the first external terminal 134a is electrically connectable to a conductor such as a bus bar 200 provided outside the battery cell 100. In the embodiment, compared to when the first conductor 130a does not have the first external terminal 134a, it is easier to electrically connect the first conductor 130a to a conductor such as the bus bar 200. Therefore, in the embodiment, compared to when the first conductor 130a does not have the first external terminal 134a, it is possible to improve the function of the first conductor 130a.

[0030] In the embodiment, the −X side surface of the first barrier layer 132a and the +X side surface of the first external terminal 134a are welded to each other by welding such as ultrasonic bonding. Therefore, the −X side surface of the first barrier layer 132a and the +X side surface of the first external terminal 134a are at least partially bonded to each other. Therefore, the first barrier layer 132a and the first external terminal 134a are electrically connected to each other. However, the bonding of the −X side surface of the first barrier layer 132a and the +X side surface of the first external terminal 134a is not limited to welding.

[0031] The first internal terminal 136a is a conductor such as a metal block. The first internal terminal 136a is at least partially located between the first barrier layer 132a and the multiple battery elements 110. The first internal terminal 136a is a protrusion that protrudes toward the +X side from approximately the center of the +X side surface of the first barrier layer 132a. However, the first internal terminal 136a may protrude toward the +X side from a portion offset from the approximately center of the +X side surface of the first barrier layer 132a. The multiple positive electrode current collectors 112 and the first internal terminal 136a are at least partially joined to each other by joining such as laser welding. Therefore, the positive electrodes of the battery elements 110 and the first internal terminal 136a are electrically connected to each other via the positive electrode current collector 112. In this embodiment, the first conductor 130a and the battery elements 110 can be more easily brought closer to each other in the X direction than when the first conductor 130a does not have the first internal terminal 136a. Therefore, in the embodiment, compared to when the first conductor 130a does not have the first internal terminal 136a, it is easier to join the first conductor 130a and the plurality of positive electrode current collectors 112 to each other. Therefore, in the embodiment, compared to when the first conductor 130a does not have the first internal terminal 136a, it is possible to improve the function of the first conductor 130a.

[0032] In the embodiment, the +X side surface of the first barrier layer 132a and the −X side surface of the first internal terminal 136a are welded to each other by welding such as ultrasonic bonding. Therefore, the +X side surface of the first barrier layer 132a and the −X side surface of the first internal terminal 136a are at least partially joined to each other. Therefore, the first barrier layer 132a and the first internal terminal 136a are electrically connected to each other. However, the joining of the +X side surface of the first barrier layer 132a and the −X side surface of the first internal terminal 136a is not limited to welding.

[0033] The second conductor 130b can be similar to the first conductor 130a, except that the first conductor 130a and the second conductor 130b are arranged approximately symmetrically, the multiple negative electrode current collectors 114 and the second internal terminals 136b are at least partially joined to each other by joining such as laser welding, and, if necessary, the first conductor 130a and the second conductor 130b contain different materials.

[0034] The first conductor 130a and the second conductor 130b may contain an appropriate material depending on the polarity of the electrodes to which the first conductor 130a and the second conductor 130b are electrically connected.

[0035] For the first conductor 130a electrically connected to the positive electrode of the battery element 110, the first barrier layer 132a, the first external terminal 134a, and the first internal terminal 136a may contain, for example, at least one of aluminum and an aluminum alloy. The first barrier layer 132a, the first external terminal 134a, and the first internal terminal 136a may contain the same material or different materials from each other.

[0036] For the second conductor 130b electrically connected to the negative electrode of the battery element 110, the second barrier layer 132b, the second external terminal 134b, and the second internal terminal 136b may contain, for example, at least one of copper and a copper alloy. The second barrier layer 132b, the second external terminal 134b, and the second internal terminal 136b may contain the same material or different materials from each other.

[0037] The second external terminal 134b may contain a material different from the materials contained in the second barrier layer 132b and the second internal terminal 136b. For example, the second external terminal 134b may contain at least one of aluminum and an aluminum alloy, while the second barrier layer 132b and the second internal terminal 136b contain at least one of copper and a copper alloy. When the second barrier layer 132b and the second internal terminal 136b contain at least one of copper and a copper alloy, the electrical connection between the negative electrode current collector 114 and the second internal terminal 136b can be improved compared to when the second barrier layer 132b and the second internal terminal 136b contain at least one of aluminum and an aluminum alloy. When the second external terminal 134b contains at least one of aluminum and an aluminum alloy, the electrical connection between the second external terminal 134b and a conductor such as a bus bar 200 outside the battery cell 100 can be improved compared to when the second external terminal 134b contains at least one of copper and a copper alloy.

[0038] The exterior film 140 has a wound portion 142 and a pair of drawn-out portions 144. The exterior film 140 has a conductor such as aluminum foil. For example, the exterior film 140 is a laminate film including the conductor and insulating layers such as resin layers located on both sides of the conductor. Therefore, the conductor within the exterior film 140 is exposed from the end of the exterior film 140.

[0039] As shown in FIGS. 1 to 3 , the wound portion 142 is wrapped around the battery element 110 and the pair of lid members 120 in the X direction. As shown in FIGS. 2 and 3 , the outer peripheral surface of the first lid base material 122a in the X direction and the inner peripheral surface of the wound portion 142 in the X direction around the first lid base material 122a are at least partially joined to each other by bonding, for example, heat fusion. As shown in FIGS. 2 and 3 , the outer peripheral surface of the first outer protrusion 124a in the X direction and the inner peripheral surface of the wound portion 142 in the X direction around the first outer protrusion 124a are at least partially joined to each other by bonding, for example, heat fusion. As shown in FIGS. 2 and 3 , the outer peripheral surface of the first inner protrusion 126a in the X direction and the inner peripheral surface of the wound portion 142 in the X direction around the first inner protrusion 126a are at least partially joined to each other by bonding, for example, heat fusion. Therefore, the battery cell 100 has a -X-side sealing portion formed by the first lid member 120a and the -X-side end of the wound portion 142. The battery cell 100 also has a +X-side sealing portion formed by the second lid member 120b and the +X-side end of the wound portion 142 in the same manner as the -X-side sealing portion. The battery cell 100 also has another sealing portion extending in the X-direction from one of the sealing portions on both sides in the X-direction to the other. For example, when the wound portion 142 is wound around the battery element 110 and the pair of lid members 120 once in the X-direction, excess portions of the wound portion 142 pulled out in either direction around the X-direction from the wound portions of the battery element 110 and the pair of lid members 120 are joined to each other by, for example, heat fusion bonding, thereby forming another sealing portion.

[0040] The pair of lid members 120 and the wound portion 142 form an accommodation space that accommodates a plurality of battery elements 110. The accommodation space is sealed by sealing portions on both sides of the battery cell 100 in the X direction and another sealing portion extending from one of the sealing portions on both sides of the battery cell 100 in the X direction to the other. In the embodiment, the accommodation space accommodates an electrolyte along with the plurality of battery elements 110.

[0041] The pair of drawn-out portions 144 are drawn out from both X-direction ends of the wound portion 142 toward the side of the pair of lid members 120 opposite the side where the battery cells 100 are located. Unless otherwise specified, the first drawn-out portion 144a and the second drawn-out portion 144b refer to the -X side drawn-out portion 144 and the +X side drawn-out portion 144, respectively. The first drawn-out portion 144a is drawn out from the -X side end of the wound portion 142 toward the -X side. The second drawn-out portion 144b is drawn out from the +X side end of the wound portion 142 toward the +X side.

[0042] The first drawer section 144a will now be described with reference to Figures 2 and 3.

[0043] 2 and 3, the first drawn portion 144a is at least partially folded back toward the side where the battery element 110 is located. Therefore, compared to when the first drawn portion 144a is not folded back and the −X side end of the first drawn portion 144a faces the −X side, it is possible to suppress a short circuit between the conductor in the exterior film 140 and the conductor present on the −X side of the first drawn portion 144a. As will be described later with reference to FIG. 4, a conductor such as a bus bar 200 may be present on the −X side of the first drawn portion 144a.

[0044] In the example shown in FIGS. 2 and 3 , the first lead portion 144a is folded back approximately 180 degrees from the −X side to the +X side toward the inner circumferential surface of the first external protrusion 124a in the X direction. Therefore, as shown in FIGS. 2 and 3 , the first lead portion 144a at least partially covers the first external protrusion 124a. This protects the first external protrusion 124a from heat generated by components surrounding the first lead portion 144a, such as the first conductor 130a. The inner circumferential surface of the first external protrusion 124a in the X direction and the outer circumferential surface of the portion of the first lead portion 144a that covers the inner circumferential surface of the first external protrusion 124a in the X direction may be at least partially joined to each other by, for example, heat fusion. Alternatively, the inner circumferential surface of the first external protrusion 124a and the outer circumferential surface of the portion of the first lead portion 144a may not be joined to each other.

[0045] When the first drawn portion 144a is not folded back and the -X side end of the first drawn portion 144a is facing the -X side, notches may be provided in the portions of the first drawn portion 144a that are located on the -X side of the four corners around the X direction of the first lid member 120a. These notches make it easier to fold the first drawn portion 144a back toward the +X side. However, these notches do not have to be provided.

[0046] The folded shape of the first drawn portion 144a is not limited to the example shown in FIGS. 2 and 3 . For example, the first drawn portion 144a may be folded back toward the outer peripheral surface of the wound portion 142 around the X-direction of the −X-side end portion. Even if the first drawn portion 144a is folded back toward the outer peripheral surface of the wound portion 142, a short circuit between the conductor in the exterior film 140 and the conductor on the −X side of the first drawn portion 144a can be suppressed compared to when the −X-side end portion of the first drawn portion 144a is not folded back and faces the −X-side. The first drawn portion 144a does not have to be folded back approximately 180 degrees from the −X side toward the +X side. For example, the first drawn portion 144a may be folded back from the −X side toward the +X side at an angle greater than 90 degrees but less than 180 degrees.

[0047] The second drawer portion 144b may be similar to the first drawer portion 144a, except that the first and second drawer portions 144a, 144b are generally symmetrically positioned.

[0048] 2 and 3 , the first conductor 130a defines a hole 131. The hole 131 penetrates the first barrier layer 132a, the first external terminal 134a, and the first internal terminal 136a in the X direction. For the sake of explanation, the hole 131 is not shown in FIG. 1 . When viewed from the X direction, the hole 131 is located in approximately the center of the first conductor 130a. However, when viewed from the X direction, the hole 131 may be located offset from approximately the center of the first conductor 130a. The hole 131 serves as a liquid injection port for injecting an electrolyte into the storage space formed by the pair of lid members 120 and the wound portion 142.

[0049] As shown in FIGS. 2 and 3 , a plug 138 is embedded in the hole 131. Therefore, the hole 131 is blocked by the plug 138. Therefore, the hole 131 can be sealed by the plug 138. The plug 138 is, for example, metal. In the embodiment, the inner circumferential surface of the hole 131 of the first conductor 130a in the X direction and the outer circumferential surface of the plug 138 in the X direction are welded to each other. Therefore, the structure of the hole 131 can be simplified compared to when the plug 138 is screwed into the hole 131. When the plug 138 is screwed into the hole 131, resin may be required to fill the space between the hole 131 and the plug 138. In contrast, in the embodiment, the hole 131 can be sealed by the plug 138 without filling the space between the hole 131 and the plug 138 with resin. However, the plug 138 may be a screw that can be screwed into the hole 131.

[0050] 2 and 3 , the plug 138 is at least partially located inside the first external terminal 134a. This makes it easier to weld the inner circumferential surface around the X direction of the hole 131 of the conductor 130 and the outer circumferential surface around the X direction of the plug 138 to each other, compared to when the plug 138 is located inside the first barrier layer 132a or inside the first internal terminal 136a. However, the plug 138 may also be at least partially located inside the first barrier layer 132a or inside the first internal terminal 136a.

[0051] 2 and 3, the hole 131 and the plug 138 are provided in the first conductor 130a. However, the hole 131 and the plug 138 may be provided in the second conductor 130b instead of or in addition to the first conductor 130a.

[0052] 2 and 3, the first cover member 120a, the first conductor 130a, the −X side end of the wound portion 142, and the first drawn-out portion 144a according to the embodiment will be further described. The matters described below regarding the first cover member 120a, the first conductor 130a, the −X side end of the wound portion 142, and the first drawn-out portion 144a can also be applied to the second cover member 120b, the second conductor 130b, the +X side end of the wound portion 142, and the second drawn-out portion 144b.

[0053] In this embodiment, heat is applied by a seal bar (not shown) from the portion of the wound portion 142 that covers the outer peripheral surface of the first outer protrusion 124a in the X direction and the portion of the first drawn-out portion 144a that covers the inner peripheral surface of the first outer protrusion 124a in the X direction, thereby at least partially heat-sealing the contact surfaces of the first outer protrusion 124a and the wound portion 142, and at least partially heat-sealing the contact surfaces of the first outer protrusion 124a and the drawn-out portion 144. Therefore, compared to when the first lid member 120a does not have the first outer protrusion 124a, it is easier to heat-seal the ends of the first lid member 120a and the wound portion 142 on the -X side. Furthermore, compared to when the first lid member 120a does not have the first outer protrusion 124a, the bonding area between the first lid member 120a and the wound portion 142 can be increased. Therefore, compared to when the first lid material 120a does not have the first external protrusion 124a, the bonding strength of the -X side end of the first lid material 120a and the wound portion 142 can be improved, and the sealing property of the sealing portion on the -X side of the battery cell 100 can be improved.

[0054] In the embodiment, as described above, heat is applied from the portion of the wound portion 142 that covers the outer peripheral surface of the first outer protrusion 124a in the X direction and the portion of the first drawn portion 144a that covers the inner peripheral surface of the first outer protrusion 124a in the X direction. Some of this heat is also propagated around the first inner protrusion 126a and the first inner protrusion 126a of the wound portion 142 in the X direction. Therefore, this heat can at least partially heat-seal the contact surfaces of the first inner protrusion 126a and the wound portion 142 to each other.

[0055] In the embodiment, the bonding area between the first lid material 120a and the wound portion 142 can be increased by the amount of the first internal protrusion 126a compared to when the first lid material 120a does not have the first internal protrusion 126a. If the bonding area between the first lid material 120a and the wound portion 142 were secured by the first external protrusion 124a when the first lid material 120a did not have the first internal protrusion 126a, the dimension of the first external protrusion 124a in the X direction would be relatively large, making it relatively difficult to miniaturize the battery cell 100 in the X direction. In contrast, in the embodiment, the bonding area on the -X side between the first lid material 120a and the wound portion 142 can be secured by both the first external protrusion 124a and the first internal protrusion 126a. Therefore, in the embodiment, compared to when the first lid member 120a does not have the first internal protrusion 126a, the dimension of the first external protrusion 124a in the X direction can be made smaller, and the battery cell 100 can be made smaller in size in the X direction. Therefore, in the embodiment, compared to when the first lid member 120a does not have the first internal protrusion 126a, it is possible to achieve both improved sealing of the sealing portion on the -X side of the battery cell 100 and a smaller size of the battery cell 100 in the X direction.

[0056] 2 and 3, the X-direction dimension of the first internal protrusion 126a from the -X side to the +X side is less than the X-direction dimension of the first external protrusion 124a from the +X side to the -X side. In the example shown in Figures 2 and 3, the X-direction dimension of the first internal protrusion 126a is the X-direction distance between the +X side surface of the first lid base material 122a and the +X side end face of the first internal protrusion 126a. In the example shown in Figures 2 and 3, the X-direction dimension of the first external protrusion 124a is the X-direction distance between the -X side surface of the first lid base material 122a and the -X side end face of the first external protrusion 124a. As described above, in the embodiment, a portion of the heat applied from the portion of the wound portion 142 covering the outer peripheral surface of the first external protrusion 124a in the X direction and the portion of the first drawn portion 144a covering the inner peripheral surface of the first external protrusion 124a in the X direction is propagated to the first internal protrusion 126a and the portion of the wound portion 142 surrounding the first internal protrusion 126a in the X direction. Therefore, in the example shown in FIGS. 2 and 3 , more heat can be easily transferred to the first internal protrusion 126a and the portion of the wound portion 142 surrounding the first internal protrusion 126a in the X direction compared to when the X direction dimension of the first internal protrusion 126a is equal to or greater than the X direction dimension of the first external protrusion 124a. Therefore, in the example shown in FIGS. 2 and 3 , the bond strength between the −X side ends of the first internal protrusion 126a and the wound portion 142 can be improved compared to when the X direction dimension of the first internal protrusion 126a is equal to or greater than the X direction dimension of the first external protrusion 124a. However, the dimension of the first inner protrusion 126a in the X direction may be equal to or greater than the dimension of the first outer protrusion 124a in the X direction.

[0057] In the example shown in FIGS. 2 and 3 , the first internal terminal 136a is located closer to the side where the multiple battery elements 110 are located than the first internal protrusion 126a. That is, the +X-side end face of the first internal terminal 136a is shifted toward the +X-side relative to the +X-side end face of the first internal protrusion 126a. Therefore, compared to when the +X-side end face of the first internal terminal 136a and the +X-side end face of the first internal protrusion 126a are flush with each other, the positive electrode current collector 112 and the first internal protrusion 126a are less likely to interfere with each other. Therefore, compared to when the +X-side end face of the first internal terminal 136a and the +X-side end face of the first internal protrusion 126a interfere with each other, the output of the battery cell 100 can be stabilized. Therefore, compared to when the +X-side end face of the first internal terminal 136a and the +X-side end face of the first internal protrusion 126a are flush with each other, both improved sealing of the −X-side sealing portion of the battery cell 100 and stabilization of the output of the battery cell 100 can be achieved. However, the +X side end face of the first internal terminal 136a and the +X side end face of the first internal protrusion 126a may be flush with each other, or the +X side end face of the first internal terminal 136a may be shifted toward the −X side with respect to the +X side end face of the first internal protrusion 126a.

[0058] FIG. 4 is a perspective view of the battery module 10 according to the embodiment.

[0059] The battery module 10 according to the embodiment includes a plurality of battery cells 100 and a plurality of bus bars 200 .

[0060] The multiple battery cells 100 are lined up in the Y direction. In the example shown in Fig. 4 , battery cells 100 arranged in the same orientation as that shown in Fig. 2 and battery cells 100 arranged in an orientation that is inverted in the X direction from the orientation shown in Fig. 2 are lined up alternately in the Y direction. Therefore, the polarities of the conductors 130 of the multiple battery cells 100 adjacent to each other in the Y direction are different from each other.

[0061] In the example shown in FIG. 4 , the multiple battery cells 100 are connected in series in order from the battery cell 100 located at one end in the Y direction to the battery cell 100 located at the other end in the Y direction. In the example shown in FIG. 4 , adjacent battery cells 100 in the Y direction are connected in series via bus bars 200 located on the −X side or +X side of the adjacent battery cells 100. The −X side bus bar 200 is electrically connected to the −X side conductor 130 adjacent in the Y direction to the battery cells 100 connected in series via the bus bar 200. The −Y side end of the −X side bus bar 200 and the −Y side conductor 130 of the adjacent conductor 130 are at least partially joined to each other by joining, for example, laser welding. The +Y side end of the −X side bus bar 200 and the +Y side conductor 130 of the adjacent conductor 130 are at least partially joined to each other by joining, for example, laser welding. Similar to the bus bar 200 on the -X side, the bus bar 200 on the +X side is electrically connected to the +X side conductor 130 adjacent in the Y direction to the battery cell 100 connected in series via the bus bar 200.

[0062] In the example shown in FIG. 4 , each bus bar 200 and the battery cells 100 connected in series via the bus bar 200 at least partially overlap in the X direction. Specifically, the −X-side bus bar 200 is located on the −X side of the portions located between the −X-side conductors 130 of the battery cells 100 connected in series via the bus bar 200. In the embodiment, as described with reference to FIGS. 2 and 3 , the first drawn portion 144a is folded back toward the −X side. Therefore, in the embodiment, a short circuit between the conductor in the exterior film 140 and the −X-side bus bar 200 can be suppressed compared to when the first drawn portion 144a is not folded back and the −X-side end of the first drawn portion 144a is facing the −X side. The same applies to the +X-side bus bar 200 and the second drawn portion 144b.

[0063] 4, first drawn portion 144a does not have to be folded back toward the −X side on all four sides around lid member 120 in the X direction. In one example, a portion of first drawn portion 144a that overlaps with bus bar 200 on the −X side in the X direction may be partially folded back toward the −X side. In this example, a short circuit between the conductor in exterior film 140 and bus bar 200 on the −X side can be suppressed compared to when the −X side end of first drawn portion 144a is facing the −X side.

[0064] The electrical connection of the multiple battery cells 100 via the bus bar 200 in the battery module 10 is not limited to the example shown in Fig. 4 . For example, the multiple battery cells 100 may be connected in parallel via the bus bar 200, with all of the multiple battery cells 100 arranged in the same orientation as that shown in Fig. 2 . Even when the multiple battery cells 100 are connected in parallel via the bus bar 200, the bus bar 200 and the battery cells 100 connected in parallel via the bus bar 200 may at least partially overlap in the X direction. Even when the bus bar 200 and the battery cells 100 at least partially overlap in the X direction, a short circuit between the conductors in the exterior film 140 and the bus bar 200 can be suppressed by folding back the drawn-out portion 144 toward the side where the battery element 110 is located.

[0065] Although the embodiments of the present invention have been described above with reference to the drawings, these are merely examples of the present invention, and various other configurations can also be adopted.

[0066] This application claims priority based on Japanese Patent Application No. 2024-033905, filed March 6, 2024, the disclosure of which is incorporated herein by reference in its entirety.

[0067] 10 Battery module, 100 Battery cell, 110 Battery element, 112 Positive electrode current collector, 114 Negative electrode current collector, 120 Lid material, 120a First lid material, 120b Second lid material, 122a First lid base material, 122b Second lid base material, 124a First outer protrusion, 124b Second outer protrusion, 126a First inner protrusion, 126b Second inner protrusion, 130 Conductor, 130a First conductor, 130b Second conductor, 131 Hole, 132a First barrier layer, 132b Second barrier layer, 134a First outer terminal, 134b Second outer terminal, 136a First inner terminal, 136b Second inner terminal, 138 Plug, 140 Outer film, 142 Wrapping portion, 144 Pull-out portion, 144a First pull-out portion, 144b Second lead-out portion, 200 bus bar

Claims

1. A battery cell comprising: a battery element; a lid material at least partially covering the battery element; and an exterior film having a first portion wrapped around the battery element and the lid material and a second portion pulled out from the first portion toward the side of the lid material opposite to where the battery element is located, wherein the second portion is at least partially folded back toward the side where the battery element is located.

2. The battery cell according to claim 1, wherein the cover member has a protrusion located on the side opposite to the side on which the battery element is located, and the second portion at least partially covers the protrusion.

3. A battery module comprising: a battery cell according to claim 1 or 2; and a bus bar electrically connected to the battery cell.

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