Battery cell

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) wound around the battery element (110) and the lid material (120). The lid material (120) has: a first external projection (124a) positioned opposite the side where the battery element (110) is positioned; and a first internal projection (126a) positioned on the side where the battery element (110) is positioned. The first external projection (124a) and the exterior film (140) are at least partially joined to each other. The first internal projection (126a) and the exterior film (140) are at least partially joined to each other.

Description

Battery cell

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

[0002] In recent years, various battery cells have been developed. As described in Patent Document 1, a battery cell may include a battery element, a lid material that at least partially covers the battery element, a conductor electrically connected to the battery element, and an exterior film wrapped around the battery element and the lid material.

[0003] International Publication No. 2021 / 157731

[0004] (Mode 1) In order to improve the sealing of the battery cell, a protrusion located on the side of the lid opposite to the side where the battery element is located and a portion of the exterior film surrounding the protrusion may be joined together by heat fusion, etc. However, simply providing a protrusion on the side of the lid opposite to the side where the battery element is located may make it difficult to reduce the size of the battery cell.

[0005] One example of an object of the first aspect of the present invention is to simultaneously improve the sealing performance of the battery cell and reduce the size of the battery cell. Other objects of the first aspect of the present invention will become apparent from the description of this specification.

[0006] (Mode 2) To facilitate the joining of a current collector drawn from a battery element and a conductor electrically connected to the battery element, the portion of the conductor joined to the current collector may be moved toward the side where the battery element is located. To increase the joining area between the lid material and the exterior material and thereby improve the sealing of the battery cell, the portion of the lid material joined to the exterior material may be extended toward the side where the battery element is located. However, when this portion of the conductor is moved toward the side where the battery element is located and this portion of the lid material is extended toward the side where the battery element is located, the current collector and the lid material may be more likely to interfere with each other. When the current collector and the lid material interfere with each other, it may be difficult to stabilize the output of the battery cell.

[0007] One example of an object of the second aspect of the present invention is to simultaneously improve the sealing performance of the battery cell and stabilize the output of the battery cell. Other objects of the second aspect of the present invention will become apparent from the description of this specification.

[0008] Aspect 1 of the present invention is as follows. 1-1. A battery cell comprising: a battery element; a lid material at least partially covering the battery element; and an exterior film wrapped around the battery element and the lid material, wherein the lid material has a first protrusion located on the side opposite to the side where the battery element is located and a second protrusion located on the side where the battery element is located, the first protrusion and the exterior film being at least partially joined to each other, and the second protrusion and the exterior film being at least partially joined to each other. 1-2. The battery cell described in 1-1, wherein the dimension of the second protrusion from the side opposite to the side where the battery element is located to the side where the battery element is located is less than the dimension of the first protrusion from the side where the battery element is located to the side opposite to the side where the battery element is located. 1-3. The battery cell described in 1-1 or 1-2, further comprising a conductor electrically connected to the battery element, wherein the second protrusion is located at least partially around the conductor. 1-4. The battery cell according to 1-3., wherein the conductor has a third protrusion joined to a current collector drawn out from the battery element, and the third protrusion is located closer to the side where the battery element is located than the second protrusion.

[0009] Aspect 2 of the present invention is as follows. 2-1. A battery cell comprising: a battery element; a lid material at least partially covering the battery element; a conductor electrically connected to a current collector drawn from the battery element; and an exterior film wrapped around the battery element and the lid material, wherein the conductor has a first portion at least partially joined to the current collector, and the lid material has a second portion at least partially joined to the exterior film, and the first portion is located closer to the side on which the battery element is located than the second portion. 2-2. The battery cell described in 2-1., wherein the first portion includes a protrusion located on the side on which the battery element is located. 2-3. The battery cell described in 2-1. or 2-2., wherein the second portion includes a protrusion located on the side on which the battery element is located. 2-4. The battery cell described in any one of 2-1. to 2-3., wherein the second portion is located at least partially around the conductor.

[0010] According to the first aspect of the present invention, it is possible to improve the sealing performance of the battery cell and reduce the size of the battery cell.

[0011] According to the second aspect of the present invention, it is possible to improve the sealing performance of the battery cell and stabilize the output of the battery cell at the same time.

[0012] Fig. 2 is a perspective view of a battery cell according to an embodiment. Fig. 3 is a schematic cross-sectional view of a first imaginary plane α shown in Fig. 1. Fig. 4 is a schematic cross-sectional view of a second imaginary plane β shown in Fig. 1. Fig. 5 is a front view of a first lid member and a first conductor according to a first example of an embodiment. Fig. 6 is a front view of a first lid member and a first conductor according to a second example of an embodiment. Fig. 7 is a schematic cross-sectional view of a part of a first lid member according to a third example of an embodiment. Fig. 8 is a schematic cross-sectional view of a part of a first lid member according to a fourth example of an embodiment.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] The first lid member 120a will be described with reference to FIGS.

[0023] 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.

[0024] The first external protrusion 124a is located on the opposite side of the first cover 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 cover 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 cover base material 122a, but may be located only partially around the entire circumference in the X direction of the first cover base material 122a.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] The first conductor 130a will be described with reference to FIGS.

[0029] 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.

[0030] 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, the first external terminal 134a can be electrically connected to a conductor such as a bus bar (not shown) provided outside the battery cell 100. In the embodiment, the first conductor 130a can be more easily electrically connected to a conductor such as a bus bar, compared to when the first conductor 130a does not have the first external terminal 134a. Therefore, in the embodiment, the functionality of the first conductor 130a can be improved, compared to when the first conductor 130a does not have the first external terminal 134a.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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 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.

[0039] The exterior film 140 is wrapped around the battery element 110 and the pair of lid members 120 in the X direction. The exterior film 140 is, for example, a laminate film.

[0040] As shown in Figures 2 and 3, the outer peripheral surface of the first lid base material 122a around the X direction and the inner peripheral surface of the portion of the exterior film 140 around the first lid base material 122a in the X direction are at least partially joined to each other by bonding such as heat fusion. As shown in Figures 2 and 3, the outer peripheral surface of the first outer protrusion 124a around the X direction and the inner peripheral surface of the portion of the exterior film 140 around the first outer protrusion 124a in the X direction are at least partially joined to each other by bonding such as heat fusion. As shown in Figures 2 and 3, the outer peripheral surface of the first inner protrusion 126a around the X direction and the inner peripheral surface of the portion of the exterior film 140 around the first inner protrusion 126a in the X direction are at least partially joined to each other by bonding such as heat fusion. Thus, the battery cell 100 has a -X side sealing portion formed by the -X side ends of the first lid material 120a and the exterior film 140. The battery cell 100 further has a +X-side sealing portion formed in the same manner as the -X-side sealing portion by the +X-side end of the second lid member 120b and the exterior film 140. The battery cell 100 further 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 exterior film 140 is wrapped around the battery element 110 and the pair of lid members 120 once in the X direction, excess portions of the exterior film 140 pulled out from the wrapped portions around the battery element 110 and the pair of lid members 120 are joined to each other by, for example, heat fusion bonding, to form another sealing portion.

[0041] The pair of lid members 120 and the exterior film 140 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.

[0042] 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 a storage space formed by the pair of lid members 120 and the exterior film 140.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 2 and 3, the −X side ends of the first lid member 120a, the first conductor 130a, and the exterior film 140 according to the embodiment will be further described. The matters described below regarding the −X side ends of the first lid member 120a, the first conductor 130a, and the exterior film 140 can also be applied to the +X side ends of the second lid member 120b, the second conductor 130b, and the exterior film 140.

[0047] In the embodiment, the outer peripheral surface of the first outer protrusion 124a in the X direction and the inner peripheral surface of the outer packaging film 140 in the X direction are at least partially heat-sealed to each other by heat applied from the inner peripheral surface of the first outer protrusion 124a in the X direction and the outer peripheral surface of the outer packaging film 140 in the X direction by a seal bar (not shown). 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 outer packaging film 140 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 outer packaging film 140 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 exterior film 140 can be improved, and the sealing property of the sealing portion on the -X side of the battery cell 100 can be improved.

[0048] In the embodiment, as described above, heat is applied to the inner circumferential surface of the first outer protrusion 124a around the X direction and the outer circumferential surface of the portion of the exterior film 140 around the first outer protrusion 124a in the X direction. Part of this heat also propagates around the X direction of the first inner protrusion 126a and the first inner protrusion 126a of the exterior film 140. Therefore, this heat can at least partially heat-seal the outer circumferential surface of the first inner protrusion 126a around the X direction and the inner circumferential surface of the portion of the exterior film 140 around the first inner protrusion 126a in the X direction to each other.

[0049] In the embodiment, the bonding area between the first lid material 120a and the exterior film 140 can be increased by the amount of the first interior protrusion 126a compared to when the first lid material 120a does not have the first interior protrusion 126a. If the bonding area between the first lid material 120a and the exterior film 140 were secured by the first exterior protrusion 124a when the first lid material 120a did not have the first interior protrusion 126a, the dimension of the first exterior protrusion 124a in the X direction would be relatively large, making it relatively difficult to reduce the size of 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 exterior film 140 can be secured by both the first exterior protrusion 124a and the first interior 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.

[0050] 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 inner circumferential surface around the X-direction of the first outer protrusion 124a and the outer circumferential surface of the portion of the exterior film 140 around the first outer protrusion 124a in the X-direction propagates to the first inner protrusion 126a and the portion of the exterior film 140 around the first inner 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 inner protrusion 126a and the portion of the exterior film 140 around the first inner protrusion 126a in the X-direction compared to when the X-direction dimension of the first inner protrusion 126a is equal to or greater than the X-direction dimension of the first outer protrusion 124a. Therefore, in the example shown in FIGS. 2 and 3 , the bonding strength of the −X-side end of the first inner protrusion 126a and the exterior film 140 can be improved compared to when the X-direction dimension of the first inner protrusion 126a is equal to or greater than the X-direction dimension of the first outer 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.

[0051] 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.

[0052] 4 is a front view of the first lid member 120a and the first conductor 130a according to the first example of the embodiment. In FIG. 4, the white circle with an X indicating the X direction indicates that the arrow pointing to the X direction extends from the front to the back of the page.

[0053] As shown in FIG. 4 , the first lid member 120a defines a recess 121. The recess 121 may extend through the first lid member 120a from one end on the −X side of the first lid member 120a to the other end on the +X side of the first lid member 120a, or may be located partially from one end on the −X side of the first lid member 120a to the other end on the +X side of the first lid member 120a. The outer peripheral surface of the first lid member 120a around the X direction, including the recess 121, and the inner peripheral surface of the exterior film 140 around the X direction are joined to each other by bonding such as heat fusion. Gas may be generated from the battery element 110 within the storage space formed by the pair of lid members 120 and the exterior film 140 due to an abnormality in the battery element 110. This gas may increase the internal pressure of the storage space. An increase in the internal pressure of the storage space generates stress in the first lid material 120a and the exterior film 140, which causes the outer peripheral surface of the first lid material 120a around the X direction and the inner peripheral surface of the exterior film 140 around the X direction to peel away from each other. In the example shown in Fig. 4, this stress tends to concentrate in the recess 121 due to the shape of the recess 121. Therefore, in the example shown in Fig. 4, when the internal pressure of the storage space increases, the outer peripheral surface of the first lid material 120a around the X direction and the inner peripheral surface of the exterior film 140 around the X direction are more likely to peel away from each other in the recess 121 than in a portion other than the recess 121. Therefore, the portion of the first lid material 120a and the exterior film 140 that are joined to each other in the recess 121 can function as a gas release valve when the internal pressure of the storage space increases.

[0054] In the example shown in Fig. 4, the recess 121 is located approximately in the center in the Y direction of the short side on the +Z side of the first lid member 120a when viewed from the X direction. Therefore, compared to when the recess 121 is located offset in the Y direction from approximately the center in the Y direction of the short side on the +Z side of the first lid member 120a, stress can be more easily concentrated in the recess 121 when the internal pressure of the storage space increases. Therefore, compared to when the recess 121 is located offset in the Y direction from approximately the center in the Y direction of the short side on the +Z side of the first lid member 120a, the bonded portion of the first lid member 120a and the exterior film 140 at the recess 121 can more easily function as a gas release valve. However, when viewed from the X direction, the recess 121 may also be located offset in the Y direction from approximately the center in the Y direction of the short side on the +Z side of the first lid member 120a. When viewed from the X direction, recess 121 may be located on the short side of first lid member 120a on the -Z side instead of or in addition to the short side of first lid member 120a on the +Z side. The number of recesses 121 located on each side may be one or two or more.

[0055] A plurality of battery cells 100 according to the embodiment may be arranged in the Y direction. When a plurality of battery cells 100 are arranged in the Y direction, by positioning the recess 121 on the +Z side or the −Z side of the first lid member 120a, it is possible to make it more difficult for gas discharged from the recess 121 to propagate to other battery cells 100 than if the recess 121 were positioned on the +Y side or the −Y side of the first lid member 120a, and it is possible to suppress the effect of the gas discharged from the recess 121 on other battery cells 100.

[0056] Fig. 5 is a front view of a first lid member 120a and a first conductor 130a according to a second example of the embodiment. The second example shown in Fig. 5 is similar to the first example shown in Fig. 4 except for the following points.

[0057] As shown in Fig. 5, when viewed from the X direction, the recess 121 may be located approximately in the center in the Z direction of the long side on the -Y side of the first lid member 120a. In the example shown in Fig. 5, the portion where the first lid member 120a and the exterior film 140 are joined together in the recess 121 can function as a gas release valve when the internal pressure of the storage space increases. Furthermore, compared to when the recess 121 is positioned offset in the Z direction from approximately the center in the Z direction of the long side on the -Y side of the first lid member 120a, this makes it easier for the portion where the recess 121 of the first lid member 120a and the exterior film 140 are joined together to function as a gas release valve. However, when viewed from the X direction, the recess 121 may be positioned offset in the Z direction from approximately the center in the Z direction of the long side on the -Y side of the first lid member 120a. When viewed from the X direction, recess 121 may be located on the long side on the +Y side of first lid member 120a instead of or in addition to the long side on the -Y side of first lid member 120a. The number of recesses 121 located on each side may be one or two or more.

[0058] The position at which the recess 121 is provided is not limited to the examples shown in Figures 4 and 5. When viewed from the X direction, the recess 121 may be located on two intersecting sides, three sides, or all four sides of the first lid member 120a. When viewed from the X direction, the recess 121 may be located at at least one of the four corners of the first lid member 120a.

[0059] Fig. 6 is a schematic cross-sectional view of a portion of a first lid member 120a according to a third example of the embodiment. The third example shown in Fig. 6 is similar to the first example shown in Fig. 4 except for the following points.

[0060] As shown in FIG. 6 , the recess 121 may be located partially from one end of the first lid member 120a on the −X side to the other end of the first lid member 120a on the +X side. In the example shown in FIG. 6 , the recess 121 extends from the +X side end face of the first internal protrusion 126a to the +X side end face of the first external protrusion 124a. In the example shown in FIG. 6 , the dimension of the recess 121 in the Y direction decreases toward the −X side. In the example shown in FIG. 6 , when viewed from the Z direction, the −Y side surface of the first lid member 120a on which the recess 121 is formed is linear. In the example shown in FIG. 6 , the portion of the recess 121 between the first lid member 120a and the exterior film 140 that is joined to each other can function as a gas release valve when the internal pressure of the storage space increases.

[0061] Fig. 7 is a schematic cross-sectional view of a portion of a first lid member 120a according to a fourth example of the embodiment. The fourth example shown in Fig. 7 is similar to the third example shown in Fig. 6 except for the following points.

[0062] As shown in Fig. 7, when viewed from the Z direction, the surface of first lid member 120a on the -Y side where recess 121 is formed may be curved. In the example shown in Fig. 7, the portion where first lid member 120a and exterior film 140 are joined to each other at recess 121 can also function as a gas release valve when the internal pressure of the storage space increases.

[0063] 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.

[0064] This application claims priority based on Japanese Patent Application No. 2024-012106 filed on January 30, 2024, and Japanese Patent Application No. 2024-012107 filed on January 30, 2024, the disclosures of which are incorporated herein in their entireties.

[0065] 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, 121 Recess, 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 Exterior film

Claims

1. A battery cell comprising: a battery element; a lid material at least partially covering the battery element; and an exterior film wrapped around the battery element and the lid material, wherein the lid material has a first protrusion located on the side opposite to where the battery element is located and a second protrusion located on the side where the battery element is located, the first protrusion and the exterior film being at least partially joined to each other, and the second protrusion and the exterior film being at least partially joined to each other.

2. The battery cell according to claim 1, wherein the dimension of the second protrusion from the side opposite to the side on which the battery element is located to the side on which the battery element is located is less than the dimension of the first protrusion from the side on which the battery element is located to the side on which the battery element is located opposite to the side on which the battery element is located.

3. The battery cell according to claim 1 or 2, further comprising a conductor electrically connected to the battery element, and the second protrusion is positioned at least partially around the conductor.

4. A battery cell as described in claim 3, wherein the conductor has a third projection joined to a current collector drawn out from the battery element, and the third projection is located closer to the side where the battery element is located than the second projection.

5. A battery cell comprising: a battery element; a lid material at least partially covering the battery element; a conductor electrically connected to a current collector drawn out from the battery element; and an exterior film wrapped around the battery element and the lid material, wherein the conductor has a first portion at least partially joined to the current collector, and the lid material has a second portion at least partially joined to the exterior film, and the first portion is located closer to the side where the battery element is located than the second portion.

6. The battery cell of claim 5, wherein the first portion includes a protrusion located on the side where the battery element is located.

7. The battery cell according to claim 5 or 6, wherein the second portion includes a protrusion located on the side where the battery element is located.

8. The battery cell of any one of claims 5 to 7, wherein the second portion is positioned at least partially around the conductor.

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