secondary batteries

Abstract

This secondary battery according to an embodiment is equipped with: an outer container which has a pair of long-side walls and a lid; an electrode body which is stored inside the outer container and has an electrode group, a positive electrode current collector tab and a negative electrode current collector tab; a pair of output terminals which are provided to the lid; a positive electrode lead which electrically connects one output terminal and the positive electrode current collector tab; and a negative electrode lead which electrically connects the other output terminal and the negative electrode current collector tab. One or more leads among the positive electrode lead and the negative electrode lead have: a first joined section which is formed from a metal sheet, positioned so as to face the lid, and joined to an output terminal; a second joined section which is positioned so as to face the inside of one long-side wall, and is joined to one tab among the positive electrode current collector tab and the negative electrode current collector tab; and a first extension part which extends from the end section of the first joined section along the other long-side wall toward the center section in the lengthwise direction of the long-side wall, and is positioned so as to face the center section in the lengthwise direction on the inside surface of the other long-side wall.

Description

[Technical Field]

[0001] FIELD An embodiment of the present invention relates to a secondary battery. [Background technology]

[0002] In recent years, high-energy-density secondary batteries, such as lithium-ion secondary batteries, have been widely used as power sources for electronic devices and electric vehicles. Such secondary batteries are constructed by housing an electrode assembly having a positive electrode and a negative electrode, and a nonaqueous electrolyte, in a rectangular outer container made of aluminum or an aluminum alloy. A positive electrode output terminal and a negative electrode output terminal are provided on the lid of the outer container. The positive electrode output terminal and the negative electrode output terminal are connected to the positive electrode and the negative electrode of the electrode assembly, respectively, via a positive electrode lead and a negative electrode lead provided in the outer container. In the manufacturing process of a secondary battery, an electrolyte solution is injected into the outer container through an injection port provided in the lid, and then the injection port is sealed while the pressure inside the outer container is reduced. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6597130 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-49064 [Patent Document 3] Japanese Patent Application Laid-Open No. 2017-86495 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, as secondary batteries have become larger in capacity and current, their outer containers have also become larger, which can lead to significant deformation of the outer container when the pressure inside the outer container is reduced. An object of an embodiment of the present invention is to provide a secondary battery capable of suppressing deformation of an outer container. [Means for solving the problem]

[0005] According to an embodiment, the secondary battery includes an outer casing having a pair of long side walls opposed to each other at a distance and a lid fixed to one end of the pair of long side walls, an electrode assembly having an electrode group and a positive electrode current collecting tab and a negative electrode current collecting tab extending from the electrode group and housed in the outer casing, a pair of output terminals provided on the lid, a positive electrode lead provided between the electrode assembly and the lid inside the outer casing and electrically connecting one of the output terminals to the positive electrode current collecting tab, and a negative electrode lead provided between the electrode assembly and the lid inside the outer casing and electrically connecting the other output terminal to the negative electrode current collecting tab. At least one of the positive electrode lead and the negative electrode lead is formed of a metal plate and has a first joint portion arranged opposite the lid and joined to the output terminal, a second joint portion arranged opposite the inner surface of one of the long side walls and joined to one of the positive electrode current collecting tab and the negative electrode current collecting tab, and a first extension portion extending from one end of the first joint portion along the other long side wall toward the longitudinal center of the long side wall and arranged opposite the longitudinal center on the inner surface of the other long side wall. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a perspective view showing the appearance of a secondary battery according to a first embodiment. [Figure 2] FIG. 2 is an exploded perspective view of the secondary battery. [Figure 3] FIG. 3 is a perspective view showing a negative electrode lead. [Figure 4] FIG. 4 is a perspective view of the negative electrode lead as seen from the back side. [Figure 5] FIG. 5 is a perspective view showing a positive electrode lead. [Figure 6] FIG. 6 is a perspective view of the secondary battery without an outer container. [Figure 7] FIG. 7 is a front view of the secondary battery with the outer container omitted. [Figure 8] 8 is a cross-sectional view of the secondary battery taken along line AA in FIG. [Figure 9]9 is a cross-sectional view of the secondary battery taken along line BB in FIG. [Figure 10] FIG. 10 is a perspective view showing a secondary battery according to a second embodiment with an outer container omitted. [Figure 11] 11 is a cross-sectional view of the secondary battery according to the second embodiment, corresponding to FIG. 8. FIG. [Figure 12] 12 is a cross-sectional view of the secondary battery according to the second embodiment, corresponding to FIG. 9. FIG. [Figure 13] FIG. 13 is a perspective view showing a secondary battery according to a third embodiment with an outer container omitted. [Figure 14] 14 is a cross-sectional view of the secondary battery according to the third embodiment, corresponding to FIG. 8. FIG. [Figure 15] 15 is a cross-sectional view of the secondary battery according to the third embodiment, corresponding to FIG. 9. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, a secondary battery according to an embodiment of the present invention will be described with reference to the drawings. The disclosure is merely an example, and appropriate modifications that are easily conceivable by those skilled in the art while maintaining the gist of the invention are naturally included within the scope of the present invention. Furthermore, the drawings may be schematic in terms of the width, thickness, shape, etc. of each part compared to the actual embodiment for the sake of clarity, but these are merely examples and are not intended to limit the interpretation of the present invention. Furthermore, in this specification and each drawing, elements similar to those previously described with reference to the previous drawings may be designated by the same reference numerals, and detailed descriptions may be appropriately simplified or omitted.

[0008] (First embodiment) As the secondary battery, the secondary battery according to the first embodiment will be described in detail. FIG. 1 is a perspective view showing the appearance of a secondary battery according to a first embodiment. As shown in the figure, the secondary battery 10 is, for example, a non-aqueous electrolyte secondary battery such as a lithium ion battery, and includes a flat, approximately rectangular outer container 12 and an electrode assembly 30 (described below) housed together with a non-aqueous electrolyte solution in the outer container 12. The outer container 12 is, for example, an outer can (battery case) formed from a metal plate such as aluminum, an aluminum alloy, iron, or stainless steel.

[0009] The outer container 12 has a container body 16 with an open top end, and a rectangular plate-shaped lid 18 that is welded to the container body 16 and closes the opening of the container body 16, forming an airtight interior. The lid 14 is provided with a pair of output terminals, i.e., a positive electrode terminal 20 and a negative electrode terminal 21, a pressure release valve (safety valve) 22, and an injection port. The injection port is sealed with a disk-shaped sealing lid 25. Here, the longitudinal direction of the lid 14 and the container body 16 is defined as X, the width direction of the lid 14 and the container body 16 perpendicular to the longitudinal direction X is defined as Y, and the height direction of the container body 16 is defined as Z.

[0010] FIG. 2 is an exploded perspective view of the secondary battery. As shown in the figure, the container body 16 of the outer container 12 has a rectangular long side wall 16a, a rectangular long side wall 16b that faces the long side wall 16a in parallel and spaced apart relation, a pair of opposing short side walls 16c, and a bottom wall 16d. A rectangular upper opening 17 is defined by the upper edges of the pair of long side walls 16a, 16b and the upper edges of the pair of short side walls 16c. The lid 14 is formed in the shape of a rectangular plate having a size approximately equal to that of the upper opening 17. The outer peripheral edge of the lid 14 is welded to the upper peripheral edge of the container body 16, and the lid 14 is fixed to the container body 16 in a state in which the upper opening 17 is closed.

[0011] Rectangular recesses 26 are formed at both ends of the lid 14 in the longitudinal direction X, and sealing materials made of an insulating material such as synthetic resin or glass, e.g., gaskets 28, are fitted into the recesses 26. Through holes T1, T2 are formed in the center of each gasket 28 and recess 26. The positive terminal 20 integrally includes a substantially rectangular terminal body 20a and a connecting rod 20b extending downward from the bottom surface of the terminal body 20a. The positive terminal 20 is attached to the gasket 28 with the connecting rod 20b inserted through the gasket 28 and the through holes T1 and T2 of the recess 26. Similarly, the negative terminal 21 integrally includes a substantially rectangular terminal body 21a and a connecting rod 21b extending downward from the bottom surface of the terminal body 21a. The negative terminal 21 is attached to the gasket 28 with the connecting rod 21b inserted through the gasket 28 and the through holes T1 and T2 of the recess 26.

[0012] The lid 14 is formed with a safety valve (pressure release valve) 22 that functions as a gas exhaust mechanism, and a non-aqueous electrolyte injection port 29. The safety valve 22 is formed in the center of the lid 14 in the longitudinal direction X, and is provided between the positive electrode terminal 20 and the negative electrode terminal 21. The safety valve 22 is formed by making a portion of the lid 14 approximately half the thickness of the other portions. When gas is generated inside the outer casing 12 due to an abnormal mode of the secondary battery 10 or the like, and the internal pressure of the outer casing 12 rises to or exceeds a predetermined value, the safety valve 22 opens, reducing the internal pressure and preventing malfunctions such as rupture of the outer casing 12. The inlet 29 is formed in the lid 14 between the positive electrode terminal 20 and the safety valve 22. After the non-aqueous electrolyte solution is injected into the outer container 12 through the inlet 29, the inlet 29 is sealed with, for example, a disk-shaped sealing lid 25.

[0013] As shown in FIG. 2, the electrode assembly 30 housed in the outer container 12 includes an electrode group formed into a flattened rectangle by, for example, spirally winding sheet-like positive and negative electrode plates with a separator interposed therebetween and then compressing them radially. The positive electrode plate includes a strip-shaped positive electrode current collector, a positive electrode active material layer formed on at least one surface of the current collector, and rectangular positive electrode current collector tabs 32a extending from multiple locations on the long side of the positive electrode current collector in the direction of the short side. The negative electrode plate has a shape similar to the positive electrode plate and includes a strip-shaped negative electrode current collector, a negative electrode active material layer formed on at least one surface of the negative electrode current collector, and rectangular negative electrode current collector tabs 32b extending from multiple locations on the long side of the negative electrode current collector in the direction of the short side. The spirally wound electrode assembly (electrode group) 30 is secured in place with a stop tape (not shown). The current collectors and current collecting tabs of the positive and negative electrode plates are, for example, made of a metal foil having a thickness of about 5 to 50 μm. The material of the metal foil can vary depending on the type of active material used in the positive and negative electrodes, but examples of the material that can be used include aluminum, an aluminum alloy, copper, and a copper alloy.

[0014] The positive electrode current collecting tabs 32a extend outward from one end of the electrode assembly (electrode group) 30 in the winding axis direction and are stacked one on top of the other in the thickness direction of the electrode assembly 30. The extending ends of the positive electrode current collecting tabs 32a are collectively clamped by a backup lead 34a bent into a U-shape. The positive electrode current collecting tabs 32a are located on one end side of the electrode assembly 30 in the longitudinal direction X. The negative electrode current collector tabs 32b extend outward from one end of the electrode assembly 30 in the winding axis direction, in the same direction as the positive electrode current collector tabs 32a, and are stacked one on top of the other in the thickness direction of the electrode assembly 30. The extending ends of the negative electrode current collector tabs 32b are collectively clamped by a backup lead 34b bent into a U-shape. The negative electrode current collector tab 32b is located on the other end side of the electrode assembly 30 in the longitudinal direction X. In this way, the positive electrode current collecting tab 32 a and the negative electrode current collecting tab 32 b extend in the same direction from one end of the electrode body 30 and are positioned apart from each other in the longitudinal direction X of the electrode body 30 . The electrode body 30 configured as described above is housed in the container body 16 with its winding axis aligned with the height direction Z of the outer container 12 and with one end face of the electrode body 30, the positive electrode current collecting tab 32a, and the negative electrode current collecting tab 32b positioned on the lid body 14 side. One end face of the electrode body 30 faces the lid body 14 at a predetermined distance.

[0015] 2, the secondary battery 10 includes an insulator 36, a positive electrode lead 40A, and a negative electrode lead 40B, which are provided in the space between the electrode assembly 30 and the lid 14 within the outer container 12. The insulator 36 is formed in the shape of a rectangular plate having approximately the same dimensions as the lid 14. The insulator 36 is disposed opposite the inner surface of the lid 14. The insulator 36 is formed with a pair of through holes T3 that respectively face the pair of through holes T2 in the lid 14, and a through hole T5 that faces the injection port 29. The positive electrode lead 40A is disposed between the insulator 36 and the positive electrode current collector tab 32a, and electrically connects the positive electrode terminal 20 and the positive electrode current collector tab 32a. The negative electrode lead 40B is disposed between the insulator 36 and the negative electrode current collector tab 32b, and electrically connects the negative electrode terminal 21 and the negative electrode current collector tab 32b. The positive electrode lead 40A and the negative electrode lead 40B will be described in detail below.

[0016] FIG. 3 is a perspective view showing the negative electrode lead, FIG. 4 is a perspective view showing the negative electrode lead as viewed from the bottom side, and FIG. 5 is a perspective view showing the positive electrode lead. 2, 3, and 4, the negative electrode lead 40B is formed by bending a conductive metal plate, for example, by bending it at a right angle to form an L-shaped cross section. In one example, the negative electrode lead 40B has a rectangular first joint portion 42a and a rectangular second joint portion 42b that is located along one long side of the first joint portion 42a and extends approximately perpendicular to the first joint portion 42a. The first joint portion 42a has a length slightly shorter than half the length of the lid 14 in the longitudinal direction X and a width slightly shorter than the width of the lid 14 in the width direction Y. The first joint portion 42a has a pair of long sides extending in the longitudinal direction X and arranged parallel to and facing the lid 14. A through-hole T4 is provided in the first joint portion 42a for joining the connection rod 21b of the negative electrode terminal 21. The first joint portion 42a further has a first extension portion 42c integrally provided at one end of the other long side (the long side opposite the long side continuing to the second joint portion 42b). The first extension portion 42c has a substantially rectangular shape and extends from the first joint portion 42a in the height direction Z along the long side wall 16a of the container body 16, and extends beyond one end of the first joint portion 42a in the longitudinal direction X toward the center of the lid 14 in the longitudinal direction X. The width of the first extension portion 42c in the height direction Z is formed to be approximately the same as the width of the second joint portion 42b described later, and the length of the first extension portion in the longitudinal direction X is formed to be approximately the same as the width of the first joint portion 42a.

[0017] The second joint portion 42b has the same length in the longitudinal direction X as the first joint portion 42a and a width in the height direction Z that is slightly smaller than the width of the first joint portion 42a. The second joint portion 42b extends from one end to the other end of one long side of the first joint portion 42a. The second joint portion 42b has a pair of long sides that extend in the longitudinal direction X and is positioned opposite the long side wall 16b of the container body 16, with an insulating member (described later) sandwiched between them. The second joint portion 42b integrally includes a second extension portion 42d that extends from one end in the longitudinal direction X beyond one end of the first joint portion 42a toward the center of the long side wall 16b in the longitudinal direction X. The second extension portion 42d has a rectangular shape and is formed with the same width as the width in the height direction Z of the second joint portion 42b and an extension length in the longitudinal direction X that is approximately equal to the width of the second extension portion 42d. The second extending portion 42d faces the first extending portion 42c in parallel with each other at a distance corresponding to the width of the first joint portion 42a. That is, the first extending portion 42c faces only the second extending portion 42d of the second joint portion 42b. The inner surface of the second joint portion 42b forms a joint surface that does not face the first extending portion 42c.

[0018] As shown in FIGS. 2 and 5 , the positive electrode lead 40A has the same symmetrical configuration and dimensions as the negative electrode lead 40B. Specifically, the positive electrode lead 40A is formed by bending a conductive metal plate, for example, by bending it at a right angle to form an L-shaped cross section. The positive electrode lead 40A has a rectangular first joint portion 42a and a rectangular second joint portion 42b located along one long side of the first joint portion 42a and substantially perpendicular to the first joint portion 42a. The first joint portion 42a integrally has a first extension portion 42c provided at one end of the other long side. The first extension portion 42c has a substantially rectangular shape and extends from the first joint portion 42a in the height direction Z along the long side wall 16a of the container body 16. The first extension portion 42c extends in the longitudinal direction X beyond one end of the first joint portion 42a toward the center of the long side wall 16a in the longitudinal direction X. The second joint portion 42b integrally includes a second extending portion 42d that extends from one end in the longitudinal direction X beyond one end of the first joint portion 42a toward the center of the lid 14 in the longitudinal direction X. The second extending portion 42d faces the first extending portion in parallel with a distance corresponding to the width of the first joint portion 42a. That is, the first extending portion faces only the second extending portion of the second joint portion 42b. In the positive electrode lead 40A, the first joint portion 42a is provided with a through hole T6 facing the injection port 29 in addition to a through hole T4 for joining the connection rod 20b of the positive electrode terminal 20. The positive electrode lead 40A and negative electrode lead 40B configured as described above are disposed between the lid 14 and the electrode body 30 inside the outer container 12, and are connected to an output terminal and a current collecting tab, respectively.

[0019] The internal structure of the assembled secondary battery 10 will now be described. 6 is a perspective view of the secondary battery with the outer container omitted, FIG. 7 is a front view of the secondary battery with the outer container omitted, FIG. 8 is a cross-sectional view of the secondary battery taken along line AA in FIG. 1, and FIG. 9 is a cross-sectional view of the secondary battery taken along line BB in FIG. 1. As shown in FIGS. 6 and 7 , the connection rod 20b of the positive terminal 20 passes through the through hole T1 of the gasket 28, the through hole T2 of the lid 14, and the through hole T3 of the insulator 36 and is fitted into the through hole T4 of the first joint portion 42a of the positive electrode lead 40A. The connection rod 20b is then joined to the first joint portion 42a by laser welding, ultrasonic welding, or the like. This fixes the positive electrode terminal 20 to the outer surface of the lid 14 via the gasket 28 and electrically connects it to the positive electrode lead 40A. The first joint portion 42a faces the inner surface of the lid 14 in parallel with the insulator 36 and extends in the longitudinal direction X from near the end of the lid 14 on the positive electrode terminal 20 side to near the center of the lid 14 in the longitudinal direction X. The through hole T6 of the first joint portion 42a is aligned with the through hole T5 of the insulator 36 and the injection port 29 of the lid 14. The lid 14 and the positive electrode lead 40A are electrically insulated from each other by an insulator 36.

[0020] The second joint portion 42b extends substantially perpendicular to the first joint portion 42a and the lid 14, and is located on one long side of the first joint portion 42a and on one long side of the lid 14. The second extension portion 42d of the second joint portion 42b is located adjacent to the center of the long side wall 16b in the longitudinal direction X. The positive electrode current collecting tab 32a and the backup lead 34a are joined to the inner surface (joining surface) of the second joint portion 42b and are electrically connected to the positive electrode lead 40A. For the joining, a method such as laser welding, ultrasonic welding, or resistance welding is used, for example. On the other hand, the first extending portion 42c is located on the other long side of the first joint portion 42a and on the other long side of the lid 14, and extends approximately perpendicular to the first extending portion 42c. Furthermore, the first extending portion 42c is located adjacent to the center of the lid 14 in the longitudinal direction X.

[0021] The connection rod 21b of the negative electrode terminal 21 passes through the through hole T1 of the gasket 28, the through hole T2 of the lid 14, and the through hole T3 of the insulator 36 and is fitted into the through hole T4 of the first joint portion 42a of the negative electrode lead 40B, and is joined to the first joint portion 42a by ultrasonic bonding or the like. As a result, the negative electrode terminal 21 is fixed to the outer surface of the lid 14 via the gasket 28 and is further electrically connected to the negative electrode lead 40B. The first joint portion 42a faces the inner surface of the lid 14 in parallel with each other, with the insulator 36 sandwiched therebetween, and extends in the longitudinal direction X from near the end of the lid 14 on the negative electrode terminal 21 side to near the center of the lid 14 in the longitudinal direction X. The lid 14 and the negative electrode lead 40B are electrically insulated by the insulator 36.

[0022] The second joint portion 42b extends substantially perpendicular to the first joint portion 42a and the lid 14, and is located on one long side of the first joint portion 42a and on one long side of the lid 14. The second extension portion 42d of the second joint portion 42b is located adjacent to the center of the lid 14 in the longitudinal direction X. The negative electrode current collecting tab 32b and the backup lead 34b are joined to the inner surface of the second joint portion 42b and electrically connected to the negative electrode lead 40B. For joining, a method such as laser welding, ultrasonic welding, or resistance welding is used, for example. On the other hand, the first extending portion 42c is located on the other long side of the first joint portion 42a and on the other long side of the lid 14, and extends approximately perpendicular to the first extending portion 42c. Furthermore, the first extending portion 42c is located adjacent to the center of the lid 14 in the longitudinal direction X.

[0023] Within the outer container 12, a rectangular frame-shaped insulating member 48 is provided between the electrode body 30 and the lid 14, and surrounds the positive electrode lead 40A and the negative electrode lead 40B. 8 and 9, the insulating member 48 is formed in the shape of a sheet or plate having a predetermined thickness from an insulating material such as synthetic resin. In one example, the insulating member 48 is attached to the inner surface of the container body 16, and covers the entire periphery of the area between the end of the upper opening side of the container body 16 and the end face of the electrode body 30. The second joint portion 42b and the second extending portion 42d of the positive electrode lead 40A abut substantially parallel to the inner surface of the long side wall 16b of the container body 16, sandwiching the insulating member 48 therebetween. The second extending portion 42d faces the center portion of the long side wall 16b in the longitudinal direction X. The first extending portion 42c of the positive electrode lead 40A abuts substantially parallel to the inner surface of the long side wall 16a on the opposite side, sandwiching the insulating member 48 therebetween. The first extending portion 42c faces the center portion of the long side wall 16a in the longitudinal direction X. The second joint portion 42b and the second extending portion 42d of the negative electrode lead 40B abut substantially parallel to the inner surface of the long side wall 16b of the container body 16, with the insulating member 48 sandwiched between them. The second extending portion 42d faces a central portion of the long side wall 16b in the longitudinal direction X. The second extending portion 42d faces the second extending portion 42d of the positive electrode lead 40A across a gap in the longitudinal direction X. The first extending portion 42c of the negative electrode lead 40B abuts substantially parallel to the inner surface of the long side wall 16a on the opposite side, with the insulating member 48 sandwiched between them. The first extending portion 42c faces a central portion of the long side wall 16a in the longitudinal direction X. The first extending portion 42c faces the first extending portion 42c of the positive electrode lead 40A across a gap in the longitudinal direction X. The positive electrode lead 40A and the negative electrode lead 40B are electrically insulated from the container body 16 by an insulating member 48.

[0024] In manufacturing the secondary battery 10 configured as described above, after a nonaqueous electrolyte solution is injected into the exterior container 12 through the injection port 29, the interior of the exterior container 12 is depressurized, and the injection port 29 is sealed with the sealing lid 25 in this depressurized state. In the secondary battery, when the pressure is reduced, the central portions of the long side walls 16a, 16b of the container body 16 in the longitudinal direction X may deform inward. It is thought that if the length of the long side walls in the longitudinal direction X is increased in line with increases in size and capacity, the exterior container becomes more susceptible to deformation.

[0025] In contrast, in the secondary battery 10 according to this embodiment, the positive electrode lead 40A and the negative electrode lead 40B have a first extension portion 42c and a second extension portion 42d that respectively face the central portions of the long side walls 16a and 16b in the longitudinal direction X. The first extension portion 42c and the second extension portion 42d press the central portions of the long side walls 16a and 16b from the inside, thereby suppressing deformation of the long side walls 16a and 16b. At the same time, deformation of the safety valve 22 provided near the central portions of the long side walls 16a and 16b is suppressed, preventing accidental opening of the safety valve and ensuring normal operation. The first extension portion 42c is sized and positioned to face only the second extension portion 42d of the second joint portion 42b. That is, the positive electrode lead 40A and the negative electrode lead 40B do not have a plate portion facing the entire second joint portion 42b. Therefore, the positive electrode lead 40A and the negative electrode lead 40B have a smaller volume than electrode leads that have a plate portion facing the entire second joint portion 42b, and the volume of the space between the electrode body 30 and the lid 14 inside the outer container 12 is correspondingly larger. By increasing the space that accommodates gas generated in the event of an abnormality, it is possible to reduce the risk of explosion of the secondary battery. Furthermore, since there is no plate portion facing the second joint portion 42b and the joint surface of the second joint portion 42b is open, the current collecting tab can be easily joined to the joint surface of the second joint portion 42b, which makes it possible to improve the assembly and productivity of the secondary battery. As described above, according to the first embodiment, it is possible to provide a secondary battery capable of suppressing deformation of the outer container.

[0026] Next, a secondary battery according to another embodiment of the present invention will be described. In the following embodiment, the same parts and components as those in the first embodiment will be assigned the same reference numerals as those in the first embodiment, and their description will be omitted or simplified. The following description will focus on the parts that are different from the first embodiment. (Second embodiment) FIG. 10 is a perspective view showing the secondary battery according to the second embodiment with the container body omitted, FIG. 11 is a cross-sectional view of the secondary battery according to the second embodiment corresponding to FIG. 8, and FIG. 12 is a cross-sectional view of the secondary battery according to the second embodiment corresponding to FIG. 9. In the first embodiment described above, two types of electrode leads with symmetrical shapes are used as the positive and negative electrode leads, whereas in the second embodiment, one type of electrode lead with the same shape and dimensions is used as the positive and negative electrode leads. As shown in the drawings, according to the second embodiment, the positive electrode lead 40A and the negative electrode lead 40B are formed to have, for example, the same configuration, shape, and dimensions as the negative electrode lead 40B in the first embodiment. That is, each of the positive electrode lead 40A and the negative electrode lead 40B integrally includes a rectangular plate-shaped first joint portion 42a, a rectangular plate-shaped second joint portion 42b perpendicular to the first joint portion 42a, a first extension portion 42c extending in the height direction Z and the longitudinal direction X from one end of one long side of the first joint portion 42a, and a second extension portion 42d extending in the longitudinal direction X from one end of the second joint portion 42b in the longitudinal direction X beyond the first joint portion 42a. However, in the second embodiment, the first joint portion 42a is provided with a through hole for connecting a connecting rod of an output terminal and a through hole that can face the injection port of the lid 14.

[0027] One of the electrode leads, for example, the negative electrode lead 40B, is arranged in the same orientation as the negative electrode lead 40B in the first embodiment described above. The first joint portion 42a of the negative electrode lead 40B faces the inner surface of the lid 14 in parallel and extends from the end on the negative electrode terminal 21 side to near the center in the longitudinal direction X. The first joint portion 42a is electrically connected to the negative electrode terminal 21. The first extension portion 42c of the first joint portion 42a abuts against the inner surface of the long side wall 16a of the container body 16 at the center in the longitudinal direction X, with the insulating member 48 sandwiched therebetween. The second joint portion 42b abuts against the inner surface of the long side wall 16b of the container body 16 at the center in the longitudinal direction X, with the insulating member 48 sandwiched therebetween. The second extension portion 42d of the second joint portion 42b abuts against the inner surface of the long side wall 16b at the center in the longitudinal direction X, with the insulating member 48 sandwiched therebetween. The negative electrode current collecting tab 32b and the backup lead 34b of the electrode body 30 are joined to the inner surface (joint surface) of the second joint portion 42b, and are electrically connected to the negative electrode lead 40B.

[0028] The other electrode lead, here the positive electrode lead 40A, is arranged in a direction inverted by 180 degrees relative to the negative electrode lead 40B. The first joint portion 42a of the positive electrode lead 40A faces the inner surface of the lid 14 in parallel and extends from the end on the positive electrode terminal 20 side to near the center in the longitudinal direction X. The first joint portion 42a is electrically connected to the positive electrode terminal 20. The first extension portion 42c of the first joint portion 42a abuts against the inner surface of the long side wall 16b of the container body 16 at the center in the longitudinal direction X, with an insulating member 48 sandwiched between them. The first extension portion 42c faces the second extension portion 42d of the negative electrode lead 40B, with a gap in the longitudinal direction X between them. The second joint portion 42b of the positive electrode lead 40A abuts against the inner surface of the long side wall 16a of the container body 16, with an insulating member 48 sandwiched between them. The second extension portion 42d of the second joint portion 42b abuts against the inner surface of the long side wall 16a at the center in the longitudinal direction X, with the insulating member 48 sandwiched between them. The positive electrode current collecting tab 32a and the backup lead 34a of the electrode body 30 are welded to the inner surface of the second joint portion 42b and electrically connected to the positive electrode lead 40A. In the second embodiment, the other configurations of the secondary battery 10 are the same as those of the secondary battery 10 according to the first embodiment.

[0029] The secondary battery 10 according to the second embodiment configured as described above can also achieve the same effects as the secondary battery according to the first embodiment. Furthermore, according to the second embodiment, by using a common electrode lead for the positive electrode lead and the negative electrode lead, it is possible to reduce the number of parts of the secondary battery and reduce manufacturing costs. In the second embodiment, the positive electrode lead 40A and the negative electrode lead 40B may be formed to have the same configuration, shape, and dimensions as the positive electrode lead 40A in the first embodiment. In this case, the positive electrode lead 40A is arranged in the same orientation as the positive electrode lead 40A in the first embodiment, and the negative electrode lead 40B is arranged in an orientation that is 180 degrees reversed.

[0030] (Third embodiment) FIG. 13 is a perspective view showing the secondary battery according to the third embodiment with the container body omitted, FIG. 14 is a cross-sectional view of the secondary battery according to the third embodiment corresponding to FIG. 8, and FIG. 15 is a cross-sectional view of the secondary battery according to the third embodiment corresponding to FIG. 9. As shown in the figure, the secondary battery 10 according to the third embodiment includes a plurality of electrode assemblies housed in an outer container 12, for example, two electrode assemblies 30A and 30B. The electrode assembly 30A is configured similarly to the electrode assembly 30 in the first embodiment described above. However, the electrode assembly 30A is formed even flatter than the electrode assembly 30, and has a thickness in the width direction Y that is approximately half the thickness of the electrode assembly 30. The electrode assembly 30A has an electrode group and a positive electrode current collector tab 32a1 and a negative electrode current collector tab 32b1 that extend from the electrode group in the height direction Z. The positive electrode current collector tab 32a1 is located at one end of the electrode assembly 30A in the longitudinal direction X. The negative electrode current collector tab 32b1 is located at the other end of the electrode assembly 30A in the longitudinal direction X. In this way, the positive electrode current collector tab 32a1 and the negative electrode current collector tab 32b1 extend in the same direction from one end of the electrode assembly 30A and are located spaced apart from each other in the longitudinal direction X of the electrode assembly 30A. The electrode body 30A configured as described above is housed in the container body 16 with its winding axis aligned with the height direction Z of the outer container 12 and with the positive electrode current collector tab 32a1 and the negative electrode current collector tab 32b1 positioned on the lid 14 side. One end face of the electrode body 30A faces the lid 14 with a gap between them.

[0031] The electrode assembly 30B has a similar configuration to the electrode assembly 30A. The electrode assembly 30B has an electrode group and a positive electrode current collecting tab 32a2 and a negative electrode current collecting tab 32b2 extending from the electrode group in the height direction Z. The positive electrode current collecting tab 32a2 is located at one end of the electrode assembly 30B in the longitudinal direction X. The negative electrode current collecting tab 32b2 is located at the other end of the electrode assembly 30A in the longitudinal direction X. The positive electrode current collecting tab 32a2 and the negative electrode current collecting tab 32b2 extend in the same direction from one end of the electrode assembly 30B and are positioned apart from each other in the longitudinal direction X of the electrode assembly 30A. The positive electrode current collecting tab 32a2 and the negative electrode current collecting tab 32b2 are positioned offset in the longitudinal direction X from the positive electrode current collecting tab 32a1 and the negative electrode current collecting tab 32b1 of the electrode assembly 30A, respectively. The electrode body 30B configured as described above is housed within the container body 16 with its winding axis aligned with the height direction Z of the outer container 12 and with the positive electrode current collecting tab 32a2 and the negative electrode current collecting tab 32b2 positioned on the side of the lid body 14, and is arranged alongside the electrode body 30A in the width direction Y.

[0032] The positive electrode current collector tab 32a1 of the electrode body 30A and the positive electrode current collector tab 32a2 of the electrode body 30B are positioned offset from each other in the longitudinal direction X without overlapping in the width direction Y. The positive electrode current collector tab 32a1 and the positive electrode current collector tab 32a2 are joined to the second joint portion 42b of the positive electrode lead 40A and are electrically connected to the positive electrode lead 40A. The negative electrode current collector tab 32b1 of the electrode body 30A and the negative electrode current collector tab 32b2 of the electrode body 30B are positioned offset from each other in the longitudinal direction X without overlapping in the width direction Y. The negative electrode current collector tab 32b1 and the negative electrode current collector tab 32b2 are joined to the second joint portion 42b of the negative electrode lead 40B and are electrically connected to the negative electrode lead 40B. In the third embodiment, the other configurations of the secondary battery 10 are the same as those of the secondary battery 10 according to the first embodiment.

[0033] The secondary battery 10 according to the third embodiment configured as described above can also achieve the same effects as the secondary battery according to the first embodiment. Furthermore, according to the third embodiment, by providing a plurality of electrode bodies, the capacity of the secondary battery can be increased.

[0034] The present invention is not limited to the above-described embodiments, and the components can be modified and embodied in practice without departing from the spirit of the invention. Furthermore, various inventions can be formed by appropriately combining multiple components disclosed in the above embodiments. For example, some components may be omitted from all the components shown in the embodiments. Furthermore, components from different embodiments may be appropriately combined. In the above-described embodiment, the positive electrode lead and the negative electrode lead have the same configuration, i.e., both leads have a first extension portion and a second extension portion, but this is not limiting, and at least one of the electrode leads may have a first extension portion. Even in such a configuration, the first extension portion of one of the electrode leads can suppress deformation of the outer container. The electrode body is not limited to a so-called wound-type electrode body in which electrode plates are wound, but may be a so-called stacked-type electrode body formed by stacking multiple electrode plates in the thickness direction.Furthermore, the electrode body is not limited to a so-called vertical-type electrode body in which the positive electrode current collecting tab and the negative electrode current collecting tab extend in the same direction, but may be a so-called horizontal-type electrode body in which the positive electrode current collecting tab and the negative electrode current collecting tab extend in opposite directions. The materials, shapes, sizes, etc. of the elements that make up the secondary battery are not limited to those in the above-described embodiment, and can be modified in various ways as necessary.

Claims

1. an outer container having a pair of long side walls opposed to each other at a distance and a lid body fixed to one end of the pair of long side walls; an electrode assembly having an electrode group and a positive electrode current collecting tab and a negative electrode current collecting tab extending from the electrode group, the electrode assembly being housed in the outer container; a pair of output terminals provided on the cover; a positive electrode lead provided between the electrode body and the lid body in the outer container, electrically connecting one of the output terminals and the positive electrode current collecting tab; a negative electrode lead that is provided between the electrode body and the lid body inside the outer container and electrically connects the other output terminal and the negative electrode current collecting tab, At least one of the positive electrode lead and the negative electrode lead is formed of a metal plate, and has: a first joint portion disposed opposite to the lid and joined to the output terminal; a second joint portion disposed opposite to the inner surface of one of the long side walls and joined to one of the positive electrode current collecting tab and the negative electrode current collecting tab; and a first extension portion extending from one end of the first joint portion along the other long side wall toward a central portion in the longitudinal direction of the long side wall, and disposed on the inner surface of the other long side wall opposite to the central portion in the longitudinal direction. Secondary battery.

2. the second joint portion integrally includes a second extension portion that extends from one end of the second joint portion along the one long side wall toward a center portion in the longitudinal direction of the one long side wall and faces the center portion in the longitudinal direction on an inner surface of the one long side wall, The secondary battery according to claim 1 , wherein the first extending portion faces only the second extending portion of the second joint portion.

3. the second joint portion has a joint surface that does not face the first extension portion, one of the positive electrode current collecting tab and the negative electrode current collecting tab is joined to the joining surface; The secondary battery according to claim 2 .

4. an insulating member provided between the long side wall and the first extension portion; The first extension portion abuts against the inner surface of the long side wall with the insulating member interposed therebetween. The secondary battery according to claim 1 .

5. an insulating member provided between the long side wall and the second joint portion; The secondary battery according to claim 2 , wherein the second joint portion and the second extension portion are in contact with the inner surface of the long side wall with the insulating member interposed therebetween.

6. The secondary battery according to claim 1 , wherein the positive electrode lead and the negative electrode lead each have the same configuration as the at least one lead and are formed in shapes symmetrical to each other.

7. 6. The secondary battery according to claim 1, wherein the positive electrode lead and the negative electrode lead each have the same configuration and shape as the at least one lead, and one of the positive electrode lead and the negative electrode lead is arranged in an inverted orientation relative to the other lead.

8. The secondary battery according to claim 1 , wherein the outer container has a pressure release valve formed in a longitudinal center portion of the lid.

9. the electrode assembly includes a first electrode assembly having an electrode group and a positive electrode current collecting tab and a negative electrode current collecting tab extending from the electrode group, the first electrode assembly being housed in the outer casing; and a second electrode assembly having an electrode group and a positive electrode current collecting tab and a negative electrode current collecting tab extending from the electrode group, the second electrode assembly being housed in the outer casing alongside the first electrode assembly, the positive electrode current collecting tab of the first electrode body and the positive electrode current collecting tab of the second electrode body are arranged side by side in the longitudinal direction and joined to the positive electrode lead, The negative electrode current collecting tab of the first electrode body and the negative electrode current collecting tab of the second electrode body are arranged side by side in the longitudinal direction and joined to the negative electrode lead. The secondary battery according to claim 1 .

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