JP2011096485A - Secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a secondary battery having a structure improved in impact resistance and vibration resistance in a vehicular secondary battery structure horizontally loading a large-sized battery element. <P>SOLUTION: The secondary battery includes: the battery element having nonaqueous electrolytic solution; a positive electrode current collecting foil and a negative electrode current collecting foil led out from both ends of the battery element; a positive electrode lead plate and a negative electrode lead plate respectively connecting the current collecting foils to a positive electrode terminal and a negative electrode terminal; and a battery case to house the battery element, the current collecting foil, and the lead plates. At both side faces of the battery element, elastic members are respectively installed between the battery element and a wall face of the longitudinal direction of the battery case. One of the elastic members is integrated with the positive electrode lead plate and forms a complex and the other of the elastic members is integrated with the negative electrode lead plate and forms a complex. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a secondary battery suitable for use in, for example, an automobile driving power source, and more particularly to a technique for improving the impact resistance and vibration resistance of a battery.

  In an in-vehicle lithium ion secondary battery, a plurality of single cells (cells) each having a positive electrode, a negative electrode, and an electrolyte are arranged in series to form an assembled battery, and a cell controller for charge / discharge control is connected. Then, the battery module is formed so as to obtain a necessary voltage.

  Such secondary battery cells include a wound battery element or a battery element in which a flat electrode and a separator are stacked in a cylindrical case, or a square or flat case. There is something stored in.

  When storing the wound battery element in a square case, the positive electrode side and negative electrode side current collector foils led out from both ends of the battery element are overlapped, and the positive electrode side and negative electrode side current collectors (leads) are overlaid respectively. Welded and stored in case. When such a battery is mounted on an automobile or the like, the battery case is fixed to the automobile or the like by the battery case itself or an electrode terminal led out of the battery case.

  However, the battery element inside the case is electrically connected to the electrode terminal by the current collector foil, but is not fixed to the case or the electrode terminal and is suspended in the case. The weight is applied only to the current collector foil, and further, a load is applied to the current collector foil due to the vibration of the automobile. Since the current collector foil is a foil-like member that electrically connects the battery element and the electrode terminal, it is vulnerable to vibration. Such vibration is light and not a problem when the secondary battery is a small battery element, but when it becomes a large battery element for automobiles, the stress applied to the current collector foil is large, cracking and cutting. There is a fear.

  In order to solve such a problem, in a cylindrical battery, a method is known in which the battery element itself is expanded and the battery element is pressed against the case to improve vibration resistance (for example, see Patent Document 1). . However, in the flat battery element that enters the square battery, there is no winding core, and no expansion pressure is uniformly generated in the radial direction. Therefore, the battery element cannot be sufficiently fixed when restrained in the case.

  Furthermore, in a rectangular battery, a technique for restraining the battery element by pressing on the case surface or changing the shape of the case surface to restrain the expansion of the battery element is known (see, for example, Patent Document 2). ). However, in the case of a large battery such as an automobile battery, the case thickness is 0.5 mm or more. If the thickness is larger than this, the shape deformation of the case surface may cause breakage of the case, which is not preferable. Further, the structure in which the battery element is followed by the case deformation has a problem that the productivity is lowered and the cost is increased.

  By the way, in recent years, a welding structure in which the direction between the positive and negative current collector foils of the battery element is filled horizontally has been studied, and the positive and negative current collector foils are exposed from the battery element to the left and right, and collected at each electrode. A technique is known in which electric foils are stacked and welded to a lead plate (see, for example, Patent Document 3). However, in the above method, since copper foil or aluminum foil is bundled and welded, when the battery element becomes large and the thickness of the aluminum foil overlap increases, the uppermost aluminum foil current collector part in contact with the lead plate In the lithium ion battery, the aluminum foil current collector may break near the end of the tab due to mechanical shock or vibration. In particular, if the electrode foil is made thin in order to increase the energy density, the vibration resistance of the welded portion is uneasy, and in the worst case, there is a risk of disconnection.

  Regarding the vibration-resistant welding technique, the technique described in Patent Document 4 is known, but this document does not describe a method for suppressing the occurrence of vibration itself. In particular, in a large battery for an automobile, the electrode group becomes large and the weight increases. In the case of a structure in which the battery elements are arranged horizontally, the electrode plate group is suspended and supported on the lid, and when this is used as a battery for an automobile, the lead and the collector foil joint portion are caused by vibration in the vertical direction. There are problems with vibration and durability. There is a connection terminal on the upper part of the winding structure, and there is a possibility that the protective film of the battery element is damaged by the battery element contact.

  As described above, there is no secondary battery structure for automobiles in which a large battery element is horizontally loaded, which does not satisfy the impact resistance and vibration resistance, and improvement of these performances has been demanded.

JP 2001-273933 A JP 2006-40879 A JP 2009-032670 A JP 2009-134971 A

  The present invention has been made to solve the above-described problems of the prior art, and has a structure in which impact resistance and vibration resistance are improved in a secondary battery structure for an automobile in which a large battery element is horizontally loaded. The object is to provide a secondary battery.

  The secondary battery of the present invention includes a battery element having a non-aqueous electrolyte, a positive electrode current collector foil and a negative electrode current collector foil derived from both ends of the battery element, and connecting the current collector foil to the positive electrode terminal and the negative electrode terminal, respectively. A secondary battery including a positive electrode lead plate and a negative electrode lead plate, and a battery case that accommodates the battery element, current collector foil, and lead plate, on both sides of the battery element, the longitudinal direction of the battery element and the battery case Each of the elastic members is integrated with the positive electrode lead plate to form a composite, and the other elastic member is integrated with the negative electrode lead plate to form a composite. It is a feature.

  In the secondary battery having the above configuration, since the two elastic members are compressed so as to sandwich the battery element, the battery element is always applied with a force by the compression force of the elastic member. Fixed. Thereby, the impact resistance and vibration resistance of the battery element are improved, and damage to the current collector foil and the like can be prevented. In addition, since a force is constantly applied to the battery element, it is possible to suppress separation of the positive and negative electrode sheets within the battery element, and the distance between the positive electrode and the negative electrode is constant, and the internal resistance in the element is constant, resulting in local deterioration. Can be prevented. Furthermore, since the heat from the battery element radiates from the elastic member to the outside of the battery through the wall surface of the battery case having a wide heat dissipation surface, the heat dissipation efficiency can be improved.

  In the secondary battery of the present invention, the battery element is a wound battery element, the elastic member has a protrusion protruding from the wall surface of the battery case toward the battery element, and the protrusion is a recess of the battery element. It is preferable to follow the above.

  When the battery element is a wound type, the curved surface portion tends to swell due to the repulsive force of the bent electrode sheet, but the flat surface portion tends to bend easily because there is no repulsive force. A recess is formed toward the center of the element. In the secondary battery having the above configuration, even when the electrode sheet plane portion is recessed toward the center of the battery element, the protrusion protrudes from the elastic member toward the battery element, and follows the shape of the recess. Since the element is pressed, the element can be held more reliably.

  ADVANTAGE OF THE INVENTION According to this invention, a battery element can be reliably fixed with respect to a battery case, the failure | damage of current collection foil can be suppressed, and the vibration resistance and heat dissipation efficiency of a battery element can be improved.

It is a see-through | perspective perspective view which shows the single battery of this invention. The battery element of this invention is shown, (a) is a front view, (b) is a side view, (c) is a front view. The current collector of the present invention is shown, (a) is a top view and (b) is a front view. It is a perspective view which shows the current collection foil fixing member of this invention. The joining process of the battery element of this invention, a collector, and a collector foil fixing member is shown, (a) is a front view, (b) is a side view, (c) is a top view. The composite_body | complex which joined the battery element of this invention, a collector, and the collector foil fixing member is shown, (a) is a front view, (b) is a side view, (c) is a top view. It is a schematic diagram which shows the process of accommodating the composite_body | complex of this invention in a battery case. The other embodiment of the collector of this invention is shown, (a) is a perspective view, (b) is a side view explaining the state which used the said collector for the battery element.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a perspective view showing a unit cell according to the present invention. The unit cell is a known lithium ion secondary battery or the like, and includes a battery case 10 and a battery lid 11. In the battery case 10, a battery element 40 made of a wound body impregnated with an electrolytic solution, and a positive electrode lead connected to a positive electrode current collector foil 41 and a negative electrode current collector foil 42 led out from both ends of the battery element 40. The plate 20b and the negative electrode lead plate 21b are accommodated. Each of the positive electrode lead plate 20b and the negative electrode lead plate 21b is provided with a positive electrode terminal 20a and a negative electrode terminal 21a so as to penetrate the battery lid 11 and be exposed to the outside of the battery. The positive electrode current collector foil fixing member 30 and the negative electrode current collector foil fixed member 31 are sandwiched by welding the positive electrode current collector foil 41 and the negative electrode current collector foil 42 to the positive electrode lead plate 20b and the negative electrode lead plate 21b, respectively. And fixed.

  Between the side surface of the battery element 40 and the longitudinal wall surface of the battery case 10, a positive electrode elastic member 20c made of a metal plate is provided, one end of which is a free end and the other end is connected to the positive electrode lead plate 20b. They are joined and integrated. Similarly, a negative electrode elastic member 21c is also provided between the opposite side surface of the battery element 40 and the longitudinal wall surface of the battery case 10, with one end being a free end and the other end being a negative electrode lead. It is joined to and integrated with the plate 21b.

  According to the unit cell of the first embodiment having the above configuration, the battery element 40 is pressed against the battery case 10 and held by the compressive force of the elastic members 20c and 21c provided on both surfaces of the battery element 40. Even when an impact or vibration is generated in the mounted vehicle or the like, the battery case 10 and the battery element 40 vibrate together, and stress is suppressed from being applied to the current collector foils 41 and 42. Damage to the current collector foil can be prevented. In addition, since a force is constantly applied to the battery element, it is possible to suppress separation of the positive and negative electrode sheets within the battery element, and the distance between the positive electrode and the negative electrode is constant, and the internal resistance in the element is constant, resulting in local deterioration. Can be prevented.

  Further, since the battery case 10 and the battery element 40 are in contact with each other via the elastic members 20c and 21c, the heat from the battery element 40 is collected by the current collector foil 41 (42), the lead plate 20b (21b), and the elastic member. Heat transfer in the order of 20c (21c), or heat transfer directly from the battery element 40 to the elastic member 20c (21c), and heat is radiated from the elastic member 40 to the outside of the battery through the wall surface of the battery case 11 having a wide heat dissipation surface. Efficiency can also be improved. In particular, since the elastic members 20c and 21c cover the two surfaces of the battery element, the heat transmitted to the battery case is dispersed, so that the degree of freedom of arrangement of the secondary battery is expanded when modularized.

Next, a method for manufacturing the unit cell of the present invention will be described.
FIG. 2 shows a battery element 40 suitable for use in the present invention. As will be described later, the battery element 40 is prepared by applying a positive electrode material and a negative electrode material to the surfaces of the positive electrode foil and the negative electrode foil to produce a sheet-like positive electrode layer and a sheet-like negative electrode layer, sandwiching a sheet-like separator therebetween, Wrap around to make. At this time, a region where the positive electrode material and the negative electrode material are not applied is secured at one end of the positive electrode foil and the negative electrode foil, and these uncoated regions are wound on both ends of the battery element 40 after winding. The foil 42 is produced. After producing the wound body, the winding core is pulled out to form a hollow portion 43 at the center of the battery element 40, and the wound body is crushed into a flat shape as shown in FIG.

  FIG. 3 shows a positive electrode current collector 20 of the present invention and a negative electrode current collector 21 having the same shape. The current collector 20 (21) includes a positive electrode terminal 20a (negative electrode terminal 21a) for charging and discharging from the outside through the battery case and a positive electrode lead plate connected to the current collector foil 41 (42) by welding. 20b (negative electrode lead plate 21b) and the elastic member 20c (21c) provided on both side surfaces of the battery element 40 are integrated. FIG. 4 also shows a positive current collector foil fixing member 30 (negative current collector) for holding the current collector foil 41 (42) from the opposite side when the current collector foil 41 (42) is welded to the lead plate 20b (21b). The electric foil fixing member 31) is shown.

  As shown in FIG. 5, current collectors 20 and 21 are attached to both side surfaces of the battery element 40, and the current collector foil 41 (42) has a lead plate 20 b (21 b) and a current collector foil fixing member 30 ( 31). The current collector foil 41 (42) is crushed as it is, bundled with the current collector foil 41 (42), and in contact with all adjacent foils, the lead plate 20b (21b) and the current collector foil fixing member 30 (31) ) To form a composite.

  Subsequently, as shown in FIG. 6, an insulating film 50 is attached around the composite and is housed in the battery case 10 as shown in FIG. 7. The insulating film 50 is provided to prevent a short circuit between the battery case 10 and the composite. As described above, the secondary battery of the present invention can be manufactured.

  FIG. 8 shows a positive electrode current collector 22 and a negative electrode current collector 23 according to another embodiment of the present invention. The current collector 22 (23) has a positive electrode terminal 22a (negative electrode terminal 23a) for charging and discharging from the outside through the battery case and a positive electrode lead plate connected by welding to the current collector foil 41 (42) 22b (negative electrode lead plate 23b) and elastic members 22c (23c) provided on both side surfaces of the battery element 40 are integrated. In the present embodiment, the elastic member 22c (23c) has a convex protrusion 22d (23d) on the side in contact with the battery element 40, as shown in the drawing.

  When the battery element 40 is a wound type, the curved surface portion (the upper end and the lower end of the battery element 40 in FIG. 8B) tends to swell due to the repulsive force of the bent electrode sheet. Since there is no repulsive force in the plane portion between the two, there is a tendency to bend easily, and the presence of the hollow portion 43 after the winding core is removed tends to form a recess toward the center of the battery element 40. . However, according to the current collector 22 (23) of the present embodiment, even when the concave portion is formed in the plane portion of the battery element 40, the elastic member protruding portion 22d (23d) formed so as to follow the concave portion shape. Since the battery element is pressed uniformly, the battery element can be held more reliably. Thereby, even if it is a case where the battery element 40 which has the hollow part 43 is dented, the vibration resistance of a battery element, impact resistance, and heat dissipation efficiency can be improved.

Hereinafter, each component of the present invention will be described in detail.
The positive electrode layer constituting the sheet-like positive electrode layer battery element has a structure in which a positive electrode material is bound on both surfaces of a positive electrode current collector made of aluminum. As the positive electrode material of this example, Li oxide powder is used, and as the conductive filler, acetylene black, ketjen black, VGCF, and the like can be given.

The negative electrode layer constituting the sheet negative electrode layer battery element has a structure in which a negative electrode material is bound on both surfaces of a negative electrode current collector made of copper or the like. As the negative electrode material of this embodiment, a carbon material that occludes and releases lithium ions or an alloy such as Sn, Pb, and Co that forms a metal compound with Li can be used. Examples of the carbon material include natural graphite, artificial graphite, activated carbon, a low-temperature carbon body calcined at 600 to 1200 ° C. (for example, pitch, mesophase pitch as an easily graphitizable carbon precursor, or phenol as a non-graphitizable carbon precursor). Resin, xylene resin, PPS, cellulose, etc.) synthesized by heat treatment in an inert atmosphere.

As the separator layer constituting the sheet-like separator layer battery element, a polyolefin microporous separator such as polyethylene, polypropylene or a nonwoven fabric separator such as polyester fiber or aramid fiber can be used.

Examples of the nonaqueous electrolyte nonaqueous solvent include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), γ- Examples include butyrolactone (γ-BL), sulfolane, acetonitrile, 1,2-dimethoxyethane, 1,3-dimethoxypropane, dimethyl ether, tetrahydrofuran (THF), and 2-methyltetrahydrofuran. Nonaqueous solvents may be used alone or in combination of two or more. Examples of the electrolyte include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium boron tetrafluoride (LiBF ₄ ), lithium hexafluoroarsenide (LiAsF ₆ ), and lithium trifluoromethanesulfonate. Examples include lithium salts such as (LiCF ₃ SO ₃ ) and bistrifluoromethylsulfonylimide lithium [LiN (CF ₃ SO ₃ ) ₂ ]. The electrolyte may be used alone or in combination of two or more. The amount of the electrolyte dissolved in the non-aqueous solvent is usually about 0.2 mol / L to 2 mol / L. Further, LiTFSI may be mixed. In addition, it may be a gel electrolyte retained by the electrolytic solution, and the retaining material may be polyethylene oxide, polypropylene oxide, vinylidene fluoride (VdF), hexafluoropropylene (HFP) or a derivative thereof, or a copolymer. Can do.

The battery element manufacturing cylinder can be a flat wound type or a laminated type, but the present invention is suitable for a wound battery element, particularly a flat wound battery element.

As the electrode terminal of the electrode terminal positive electrode terminal and the negative electrode terminal, a metal such as copper, nickel, aluminum, stainless steel, an alloy containing these, or a metal plated with these metals as a base material can be used. In order to increase the bonding area between the current collector foil and the terminal portion, a plate shape is preferable.

To process the shape of the battery case bottom surface, aluminum, stainless alloy, or resin can be used, but an aluminum alloy produced by impact molding or transfer press processing is preferable. The processing of the bottom surface of the case is preferably R10.0 mm or more and R90.0 mm or less on the outside or inside. The case preferably has a structure in close contact with the battery element, which reduces the space at the bottom of the case, and when the electrolyte is injected, the liquid level rises, so that the battery element absorption is improved and the impregnation time can be shortened. is there.

The insulating film is preferably an insulating film having an electrolytic solution resistance, such as PP, PE, or a sheet-like separator.

Current collector In general, Al is often used for the positive electrode and Cu is used for the negative electrode, and a metal that does not elute due to the potential of the positive and negative electrodes is preferable. In order to prevent electrolytic corrosion, it is preferable to use the same material as the current collector foil used for each of the positive electrode and the negative electrode.

As described above, according to the present invention, the following effects can be obtained.
1) Since the battery element is fixed to the battery case by the spring elasticity of the elastic member of the current collector, vibration resistance and impact resistance can be improved, and destruction of the terminal joint portion can be prevented.
2) By connecting the current collector foil and the lead plate, the heat inside the battery element is transferred from the current collector foil to the elastic member via the lead plate, and the battery element and the elastic member are in contact with each other. As a result, heat can be transferred from the battery element to the battery case via the elastic member, and the heat transfer area can be increased, so that heat dissipation is improved and the cooling performance of the cell can be improved. Further, even in a large battery element, internal heat variation can be reduced, local deterioration in the electrode can be suppressed, and the life can be improved.
3) In relation to 2), even if the internal temperature of the cell rises due to an abnormality such as an internal short circuit, thermal runaway can be suppressed by heat dissipation from the current collector.
4) Since only the shape of the current collector is changed, there is no increase in the number of parts, and no special manufacturing technique is required, so that no capital investment is required and the cost is low.
5) The pressing structure by the elastic member can be applied to the electrode body of either a wound type or a laminated type, but in particular, in the flat wound element structure, there is a problem that loosening is likely to occur when the winding shaft is pulled out. Due to the slackness, gas is generated between the electrode plates due to decomposition of the electrolyte solution, especially in long-term use. However, gas tends to stay in the center of the element at a high temperature, and the distance between the electrode plates in this part is large. It tends to cause local deterioration. Since this structure is equipped with a structure that presses the current collector at the same time, the distance between the positive and negative electrode plates is constant, the internal resistance in the element is uniform, and the internal resistance can be reduced. In addition, since the distance between the electrode plates does not increase, local deterioration in the electrodes can be suppressed, and durability reliability can be improved.

Hereinafter, specific production examples of the present invention will be described.
The electrode for producing the battery element was an electrode body having a positive electrode coating width of 120 mm, a negative electrode coating width of 122 mm, and an uncoated portion of 15 mm. A separator having a thickness of 25 μm was used. As the negative electrode current collector foil, a Cu foil was used with a thickness of 10 μm, and as the positive electrode current collector foil, an Al foil was used with a 12 μm foil. LiNi _0.33 Mn _0.33 Co _0.33 O ₂ having a particle diameter D ₅₀ = 12 μm was used as the positive electrode active material, and artificial graphite particles having a particle diameter of 22 μm were used as the negative electrode active material. An electrode was prepared using PVDF as a binder, and the thickness of the active material layer after pressing the electrode body was 100 μm. The electrode density of the negative electrode was 1.5 g / cm ² , and the electrode density of the positive electrode was 3.8 g / cm ³ .

  The separator was wound with a biaxial core, and the positive and negative electrodes were inserted between the separators and wound. After completion, the winding core was removed, and a flat battery element having a width of 161 mm, a thickness of 35 mm, and a height of 80 mm shown in FIG. 2 was produced. As the current collector foil, uncoated portions of Al and Cu were left and right on the positive electrode and the negative electrode, respectively.

Production of current collector A pair of positive and negative current collectors shown in FIG. 3 was produced. The elastic member portion of the current collector had a plate thickness of 1 mm, a width of 115 mm, and a height of 50 mm, and was molded so as to function as a leaf spring by being bent into a waveform. The lead plate portion had a plate thickness of 1 mm, a width of 5 mm, and a height of 50 mm. Both the positive and negative electrodes were integrated with the battery lid before the current collector foil welding in the next step.

Junction of current collector (production of composite)
The battery element was sandwiched between the positive and negative current collectors, and the current collector foils of the positive and negative electrodes were sandwiched between the current collector and the current collector foil fixing member and welded. The place of welding was a portion 5 mm from the end face of the current collector foil. In this way, a composite was produced.

The outer periphery of the composite body that was fixedly joined and integrated with the composite body was wound around and fixed with an insulating sheet of PP film.

Case production and loading 3003 using an aluminum alloy, the case plate thickness was 1 mm and the case outer dimensions were L165 × W40 × H85 mm, 1 mm by impact molding. The composite produced above was inserted into this battery case, the upper part was sealed with a battery lid, the lid and the case were sealed by YAG welding, and then vacuum dried at 80 ° C. for 24 hours.

After the impregnation vacuum drying, the inside of the cell was depressurized in the glove box, and then impregnation was performed by injecting 1.0 M electrolyte LiPF ₆ / (EC + DMC + EMC). CCCV charging was performed for 8 hours at a current of 0.2 C up to 4.2 V with a charging / discharging device. Thereafter, the pressure was reduced and degassed, and the injection hole was welded and sealed to complete the cell. Discharge was performed up to SOC 50, and initial resistance was measured (capacity was equivalent to 60 Ah).

[Comparative example]
A cell of a comparative example was produced in the same manner as in the example except that no elastic member was provided.

  The cell of each example and comparative example is fixed to a vibration tester, and a frequency range of 20 to 400 Hz, a sweep time of 10 minutes, and three directions of 48 hours are applied according to an automobile parts vibration test method JIS D1601, and an acceleration is 15G. The test was conducted at After the test, the internal resistance was calculated by a four-point method at 10, 20, 30, and 40 A and compared. The results are shown in Table 1. As a result, in the comparative example, an unstable voltage was shown, so that the capacity could not be measured. When the inside was disassembled and confirmed, cracks were confirmed in the positive electrode, the terminal metal of the positive electrode, and the current collector foil.

  According to the present invention, the impact resistance and vibration resistance of the electrode element can be improved, and further, since the battery element has a high cooling effect, it is extremely promising when applied to an in-vehicle lithium ion secondary battery system. .

10 ... Battery case,
11 ... Battery cover,
12 ... electrolyte inlet,
20, 22 ... positive electrode current collector,
20a, 22a ... positive terminal,
20b, 22b ... positive electrode lead plate,
20c, 22c ... positive electrode elastic member,
21, 23 ... negative electrode current collector,
21a, 23a ... negative electrode terminal,
21b, 23b ... negative electrode lead plate,
21c, 23c ... negative electrode elastic member,
22d ... positive electrode elastic member protrusion,
23d ... negative electrode elastic member protrusion,
30 ... Positive current collector foil fixing member,
31 ... Negative electrode current collector foil fixing member,
40 ... Battery element,
41 ... positive electrode current collector foil,
42 ... negative electrode current collector foil,
43 ... hollow part,
50: Insulating film.

Claims (2)

A battery element having a non-aqueous electrolyte, a positive current collector foil and a negative current collector foil led out from both ends of the battery element, and a positive electrode lead plate and a negative electrode lead connecting the current collector foil to a positive electrode terminal and a negative electrode terminal, respectively A secondary battery comprising a plate and a battery case that houses the battery element, the current collector foil, and the lead plate,
On both side surfaces of the battery element, elastic members are provided between the battery element and the wall surface in the longitudinal direction of the battery case, respectively.
One of the elastic members is integrated with the positive electrode lead plate to form a composite,
2. The secondary battery according to claim 1, wherein the other elastic member is integrated with the negative electrode lead plate to form a composite. The battery element is a wound battery element, and the elastic member has a protrusion that protrudes from the wall surface of the battery case toward the battery element, and the protrusion follows the recess of the battery element. The secondary battery according to claim 1, wherein:

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