JP2012124007A - Secondary battery, and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery having a smaller curvature of an electrode lead, and a low incidence of trouble of minute short circuit.SOLUTION: The secondary battery comprises: an electrode group which has a wound material formed by winding a stack of positive and negative electrodes and a separator sandwiched between the positive and negative electrodes, a positive electrode lead connected with the positive electrode, and a negative electrode lead connected with the negative electrode; and a conductive housing case which has an enclosure having a housing hole for housing the electrode group and a bottom face intersecting with a winding axis of the electrode group, and which has a seal member sealing up the housing hole, and having an electrode terminal. In the secondary battery, one of the positive and negative electrode leads is connected to the inside face of the housing hole, and the other is connected to the electrode terminal.

Description

  The present invention relates to a secondary battery and a method for manufacturing the same.

  In recent years, secondary batteries such as nickel metal hydride batteries, nickel cadmium batteries, lithium batteries, and lithium ion batteries are being widely used in portable electronic devices and the like. Such secondary batteries are characterized by having a high electromotive force of 3 to 4 V, and their excellent performance has attracted attention (for example, Patent Document 1).

  A method of manufacturing such a secondary battery includes: winding a laminate composed of a sheet-like positive electrode and a negative electrode and a separator disposed between the positive electrode and the negative electrode in a spiral shape to form an electrode group; A step of welding a lead derived from one electrode of the electrode group to the bottom of the case; and a step of welding a lead derived from the other electrode of the electrode group to the sealing lid; Attaching a sealing lid to the opening of the housing (see, for example, Patent Document 2).

  1A to 1C show a part of a method for manufacturing a secondary battery disclosed in Patent Document 2. FIG. FIG. 1A shows a step of forming the electrode group 5. As shown in FIG. 1A, the electrode group 5 is formed by winding a laminate composed of the positive electrode 1, the negative electrode 2, and the separator 3 disposed between the positive electrode 1 and the negative electrode 2. Further, a positive electrode lead 1 a connected to the positive electrode 1 and a negative electrode lead 2 a connected to the negative electrode 2 protrude from the electrode group 5.

  FIG. 1B shows a step of inserting the electrode group 5 into the housing 7. As shown in FIG. 1B, when the electrode group 5 is inserted into the housing 7, the negative electrode lead 2a is bent into an L shape.

  FIG. 1C shows the step of welding the negative electrode lead 2 a to the bottom inner surface of the housing 7. As shown in FIG. 1C, the negative electrode lead 2 a is welded to the bottom inner surface of the housing 7 by irradiating a laser from the outside of the bottom of the housing 7.

JP 2003-109655 A Japanese Patent Laid-Open No. 08-293299

  However, if an electrode lead such as a negative electrode lead is bent as disclosed in Patent Document 2, the electrode lead may generate heat at the bending point during use of the secondary battery, which may deteriorate the performance of the secondary battery.

  Further, as disclosed in Patent Document 2, in the method of joining the electrode lead and the inner surface of the casing by irradiating the laser from the outside of the casing, the cause of the micro short-circuit failure is caused inside the casing. There is a risk that a small short-circuit failure (OCV failure) may occur. Further, it is difficult to adjust the laser output by the method of joining the electrode lead and the inner surface of the casing by irradiating the laser from the outside of the casing. For example, when the laser output is increased in order to ensure the bonding strength between the electrode lead and the housing, a through hole may be formed in the housing.

  The present invention has been made in view of this point, and an object of the present invention is to provide a secondary battery in which the bending of electrode leads is small and the incidence of minute short-circuit defects is low.

The first of the present invention relates to the secondary battery shown below.
[1] A wound product of a laminate of a positive electrode and a negative electrode, a separator sandwiched between the positive electrode and the negative electrode, a positive electrode lead connected to the positive electrode, and a negative electrode lead connected to the negative electrode Conductive accommodation comprising an electrode group, a housing having a housing hole for housing the electrode group and a bottom surface intersecting a winding axis of the electrode group, and a sealing member for closing the housing hole and having an electrode terminal A secondary battery having a case, wherein one of the positive electrode lead and the negative electrode lead is joined to an inner surface of the accommodation hole, and the other is joined to the electrode terminal.
[2] The secondary battery according to [1], wherein the positive electrode lead or the negative electrode lead bonded to the inner surface of the accommodation hole protrudes from the vicinity of the outer periphery of the electrode group.
[3] The positive electrode lead or the negative electrode lead joined to the inner surface of the housing hole protrudes from the electrode group toward the sealing member, and the inside of the housing hole between the electrode group and the sealing member The secondary battery according to [1] or [2], which is bonded to a side surface.
[4] The secondary battery according to [3], wherein the sealing member further includes a sealing plate having a through hole through which the electrode terminal passes, and the electrode terminal has a constriction so as to sandwich the through hole. .
[5] The secondary battery according to any one of [1] to [4], wherein the positive electrode lead is bonded to an inner surface of the accommodation hole, and the housing includes aluminum.

2nd of this invention is related with the manufacturing method of the secondary battery shown below.
[6] A method for manufacturing the secondary battery according to any one of [1] to [5], comprising: preparing a housing having the accommodation hole; and placing the electrode group in the accommodation hole. A method for manufacturing a secondary battery, comprising: inserting, joining the positive electrode lead or the negative electrode lead to an inner surface of the accommodation hole, and closing the accommodation hole with the sealing member.
[7] The method for manufacturing a secondary battery according to [6], wherein the positive electrode lead or the negative electrode lead is bonded to the inner surface of the accommodation hole by wedge bonding, stirring bonding, or ultrasonic bonding.

  In the secondary battery of the present invention, the bending of the electrode lead joined to the housing of the housing case is small. For this reason, in the secondary battery of this invention, there is little heat_generation | fever of the electrode lead joined to the housing | casing at the time of use. Further, in the secondary battery of the present invention, since the electrode lead is joined to the casing by a method that does not generate sparks, the incidence of micro short circuit failure is low. Moreover, in this invention, since laser welding is not used, there is little possibility that a through-hole will arise in a housing | casing.

The figure which shows the manufacturing flow of the secondary battery disclosed by patent document 2. FIG. Sectional drawing of the secondary battery of Embodiment 1 The perspective view of the electrode group of Embodiment 1 Sectional drawing of the electrode group of Embodiment 1 The figure which shows the manufacturing flow of the secondary battery of Embodiment 1. FIG. Sectional drawing of the secondary battery of Embodiment 2 Sectional drawing of the secondary battery of Embodiment 3.

  The secondary battery of the present invention has an electrode group and a housing case for housing the electrode group. Moreover, the secondary battery of this invention has electrolyte solution. Each component will be described below.

1) Housing Case The housing case includes a housing having a housing hole for housing the electrode group and the electrolytic solution, and a sealing member that closes the housing hole of the housing. The housing case is partly or entirely electrodynamic so that electricity can be taken out through the housing. The housing may have one accommodation hole (see Embodiments 1 and 2) or a plurality of accommodation holes (see Embodiment 3). When the housing has a plurality of housing holes, the electrode group and the electrolytic solution are housed in each housing hole. The housing has a bottom surface that intersects a winding axis of an electrode group described later.

  The shape of the accommodation hole is appropriately selected depending on the shape of the electrode group to be accommodated. For example, when the electrode group is a cylinder, the accommodation hole is also cylindrical; when the electrode group is a prism, the accommodation hole is also prismatic.

  Examples of the housing material include aluminum, magnesium, iron, nickel, carbon, copper, and alloys thereof. The material of the housing is appropriately selected depending on whether a positive electrode lead or a negative electrode lead described later is bonded to the housing. For example, when the positive electrode lead is joined to the housing, the housing material is preferably aluminum or an aluminum alloy. When the negative electrode lead is joined to the casing, the casing material is preferably iron, nickel, copper, or the like. From the viewpoint of reducing the weight of the secondary battery, the housing material is preferably aluminum or an aluminum alloy.

  The side part and the bottom part of the casing may be manufactured integrally (see Embodiments 1 and 2), or after the side part of the casing and the bottom part of the casing are separately manufactured, You may join a side part and the bottom part of a housing | casing (refer Embodiment 3).

  The manufacturing method of the housing is not particularly limited, but it is manufactured by, for example, extrusion molding, impact molding, or squeezing. Extrusion molding is a method of molding a material shape by extruding a heated billet through a die die. Extrusion molding can produce a housing at low cost. A member produced by extrusion molding is also referred to as an extruded profile.

  The sealing member has an electrode terminal and a sealing plate. Either a positive electrode lead or a negative electrode lead described later is bonded to the electrode terminal. Therefore, the electrode terminal functions as a positive electrode or a negative electrode terminal. The sealing plate has a through hole through which the electrode terminal passes. In order to close the accommodation hole with the sealing member, the sealing plate may be welded to the housing.

  The material of the electrode terminal is appropriately selected depending on whether the electrode terminal functions as a positive electrode terminal or a negative electrode terminal. For example, when an electrode terminal functions as a positive electrode terminal, aluminum is contained in the example of the material of an electrode terminal. On the other hand, when the electrode terminal functions as a negative electrode terminal, examples of the material of the electrode terminal include iron, nickel, copper, and the like.

  The electrode terminal is insulated from the housing. As will be described later, in the present invention, since the casing functions as a positive electrode or a negative electrode terminal, the secondary battery is short-circuited when the electrode terminal and the casing are electrically connected.

In order to insulate the electrode terminal from the housing, the sealing plate may be a non-conductive material, or the sealing plate may be a conductive material, and an insulating material may be interposed between the electrode terminal and the sealing plate (FIG. 2). reference).
Although the structure of a sealing member is not specifically limited, It is preferable that an electrode terminal has a constriction so that the edge of the through-hole of a sealing plate may be pinched | interposed (refer FIG. 2). Thus, an electrode terminal pinches | interposes the edge of the through-hole of a sealing plate, It becomes difficult to leak electrolyte solution from between a sealing plate and an electrode terminal, and it can prevent that electrolyte solution leaks out from an accommodation hole. On the other hand, when the electrode terminal has a constriction so as to sandwich the edge of the through hole of the sealing plate, a gap is formed between the sealing member and the electrode group (see FIG. 2).

  The electrode terminal may have a through-hole along the winding axis of the electrode group (see Embodiment 2, FIG. 6). When the electrode terminal has a through hole along the winding axis of the electrode group, the electrode lead joined to the electrode terminal can be joined to the inner surface of the through hole of the electrode terminal, and the electrode lead joined to the electrode terminal It is possible to shorten the length and reduce the bending of the electrode lead (see FIG. 6). Moreover, when an electrode terminal has a through-hole, the electrolyte solution mentioned later can be inject | poured through the through-hole of an electrode terminal. When the electrode terminal has a through hole, the electrode terminal is covered with a cap that closes the through hole (see FIG. 6).

2) Electrode group The electrode group has a laminate of a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode (see FIG. 3). The electrode group also includes a positive electrode lead connected to the positive electrode and a negative electrode lead connected to the negative electrode. The positive electrode lead and the negative electrode lead protrude in the winding axis direction from the electrode group. The electrode group may be columnar or prismatic as long as it is columnar.

  The positive electrode has a positive electrode current collector and a positive electrode mixture layer disposed on the positive electrode current collector. The negative electrode has a negative electrode current collector and a negative electrode mixture layer disposed on the negative electrode current collector.

  The positive electrode current collector and the negative electrode current collector are electrode substrates that retain the positive electrode mixture layer or the negative electrode mixture layer and have a current collecting function. The positive electrode current collector and the negative electrode current collector are appropriately selected from metal foils such as aluminum foil, copper foil, and nickel foil, depending on the type of unit. For example, when the unit functions as a lithium ion battery, the positive electrode current collector is an aluminum foil and the negative electrode current collector is a copper foil. Generally, an aluminum foil or aluminum alloy foil having a thickness of 5 to 30 μm is used as the positive electrode current collector, and a copper foil having a thickness of 5 to 25 μm is often used as the negative electrode current collector.

  The positive electrode mixture layer is a layer formed by binding particles of a positive electrode active material with a binder. The binder binds between the current collector and the active material and between the active materials. The positive electrode mixture layer includes a conductive material and may further include other substances. The positive electrode mixture layer is generally disposed on both surfaces of the positive electrode current collector, as shown in FIG.

Material of the positive electrode active material particles, for example, lithium cobalt oxide, lithium nickel oxide, lithium transition metal oxides such as lithium manganate and, FeS, transition metal sulfides such as TiS _2, polyaniline, organic compounds such as polypyrrole, These compounds are partially substituted with elements. The average particle diameter of the positive electrode active material particles is 1 to 100 μm.

  The material of the binder is not particularly limited, and is, for example, a thermoplastic resin such as a resin containing a fluorine atom or a rubber particle binder having an acrylate unit. Examples of the resin containing a fluorine atom include polyvinylidene fluoride (PVdF), a modified polyvinylidene fluoride, polytetrafluoroethylene (PTFE), and the like. The binder material may further contain an acrylate monomer or an acrylate oligomer into which a reactive functional group has been introduced.

  Examples of the conductive material include acetylene black, ketjen black, channel black, furnace black, carbon black such as lamp black and thermal black, and various graphites.

  The negative electrode mixture layer is a layer formed by binding particles of a negative electrode active material with a binder. The negative electrode mixture layer contains a conductive material and may further contain other substances. Moreover, the negative mix layer is generally arrange | positioned on both surfaces of the negative electrode collector, as FIG. 4 showed.

The material of the negative electrode active material is, for example, a carbon-based active material such as graphite or coke, a silicon-based composite material such as metal lithium, lithium transition metal nitride, or silicide.
Examples of the binder material contained in the negative electrode mixture layer include polyvinylidene fluoride (PVDF) and modified products thereof, styrene-butadiene copolymer rubber particles (SBR) and modified products thereof, and the like. Further, the conductive material contained in the negative electrode mixture layer may be the same as the conductive material contained in the positive electrode mixture layer.

  The separator is a member that insulates the positive electrode from the negative electrode and ensures ionic conductivity between the positive electrode and the negative electrode. The material of the separator is not particularly limited as long as it is a stable material when the power supply device is used, and is, for example, an insulating polymer porous film. The separator is, for example, inorganic particles such as alumina silica, magnesium oxide, titanium oxide, zirconia, silicon carbide, silicon nitride, polyethylene, polypropylene, polystyrene, polyacrylonitrile, polymethyl methacrylate, polyvinylidene fluoride, polytetrafluoroethylene, polyimide. It can be produced by applying, drying and rolling a mixture of organic particles such as the above, a mixture of inorganic particles and organic particles, a binder, a solvent, various additives and the like. Although the thickness of a separator is not specifically limited, For example, it is 10-25 micrometers.

  The positive electrode lead and the negative electrode lead are conductive members protruding from the electrode group. The material of the positive electrode lead includes, for example, aluminum. On the other hand, the material of the negative electrode lead is, for example, iron, nickel, copper or the like. The shape of the electrode lead is not particularly limited, but for example, a strip shape is preferable.

  One of the positive electrode lead and the negative electrode lead is bonded to the electrode terminal, and the other is bonded to the housing. In the present invention, an electrode lead (positive electrode lead or negative electrode lead) to be bonded to the housing is bonded to the inner surface of the housing hole of the housing. For this reason, in this invention, a housing | casing electrically connects with a positive electrode or a positive electrode, and a housing | casing functions as a positive electrode or a negative electrode.

  It is preferable that an electrode lead (hereinafter also referred to as “joining lead”) joined to the inner surface of the housing hole protrudes from the vicinity of the outer periphery of the electrode group. Specifically, it is preferably disposed within 15 μm to 150 μm from the outer peripheral surface of the electrode group. By disposing the joining lead in the vicinity of the outer periphery of the electrode group, the distance between the joining lead and the inner surface of the accommodation hole can be reduced, and the bending of the joining lead can be reduced. On the other hand, if the bonding lead protrudes from the vicinity of the winding axis of the electrode group, the distance between the bonding lead and the inner surface of the receiving hole becomes longer, and when the bonding lead is bonded to the inner surface of the receiving hole, Bending becomes large.

  Further, it is not preferable that the joining lead contacts the bottom surface of the casing or the sealing member. This is because when the bonding lead comes into contact with the bottom surface of the casing or the sealing member, the bending of the bonding lead increases (see FIG. 1B).

  As described above, in the present invention, since the coupling lead protruding from the vicinity of the side surface of the electrode group is bonded only to the inner side surface of the accommodation hole, the bending of the bonding lead is small. Here, “the bending of the coupling lead is small” means that the coupling lead does not bend at all, or that the radius of curvature of the bending portion of the coupling lead is equal to or greater than the plate thickness of the coupling lead. For example, when the plate thickness of the lead is 0.15 mm, the combined lead curvature radius is 0.15 mm or more. As described above, in the present invention, since the bending of the joining lead is small, the joining lead hardly generates heat when the secondary battery is used.

  Moreover, it is not preferable that the joint portion of the joint lead in the electrode group is exposed on the outer peripheral surface in the case of the electrode group. This is because if the bonding lead is exposed on the outer peripheral surface of the electrode group, the bonding lead may be caught by the casing or the electrode group may be damaged when the electrode group is inserted into the accommodation hole.

  The joining lead may protrude toward the bottom surface side of the housing or may protrude toward the sealing member side. When the joining lead protrudes toward the sealing member, the joining lead is joined to the inner side surface of the accommodation hole between the electrode group and the sealing member. On the other hand, when the joining lead protrudes to the bottom surface side of the housing, the joining lead is joined to the inner surface of the accommodation hole between the electrode group and the bottom surface.

  Further, when the joining lead is joined to the inner surface of the accommodation hole between the electrode group and the sealing member, the joining lead is joined to the inner surface of the accommodation hole between the electrode group and the sealing member. A gap is formed. When the joining lead is joined to the inner surface of the accommodation hole between the electrode group and the bottom surface, a gap for joining the joining lead to the inner surface of the accommodation hole is provided between the electrode group and the bottom surface. It is formed.

  Thus, in the present invention, in order to join the joining lead to the inner side surface of the accommodation hole, it is required that a gap be formed between the electrode group and the bottom surface of the housing or the sealing member. For this reason, it is conceivable that the space use efficiency of the accommodation hole is lowered. However, as described above, in the case of closing the accommodation hole with the sealing member having the electrode terminal confined so as to sandwich the edge of the through hole of the sealing plate, the joining lead is connected to the inner surface of the accommodation hole between the electrode group and the sealing member. By joining to the housing, the space of the housing can be effectively utilized. A sealing member having an electrode terminal confined so as to sandwich the edge of the through hole of the sealing plate, and a gap between the sealing member and the electrode group formed when the accommodation hole is closed (see reference numeral G in FIG. 2) This is because the joining lead can be joined.

  A method for joining the joining lead to the inner surface of the accommodation hole is not particularly limited, but wedge bonding, stirring joining or ultrasonic joining is preferable. This is because when a bonding lead is bonded by wedge bonding, stir bonding, or ultrasonic bonding, a spark that causes a micro short-circuit failure does not occur.

3) Electrolytic solution The electrolytic solution contains a solvent and an electrolyte.

  The solvent is appropriately selected depending on the type of secondary battery. For example, when the secondary battery functions as a lithium ion battery, the solvent is a non-aqueous solvent. Examples of non-aqueous solvents include ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, γ-butyrolactone, sulfolane, acetonitrile, 1,2-dimethoxyethane, 1,3-dimethoxypropane, diethyl ether , Tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, and the like. These non-aqueous solvents may be used alone or in combination of two or more.

  On the other hand, when the secondary battery functions as a nickel-hydrogen battery, a nickel-cadmium battery, an air zinc battery, a lithium air battery, or the like, the solvent is water.

The electrolyte is also appropriately selected depending on the type of secondary battery. For example, when the secondary battery functions as a lithium ion battery, examples of the electrolyte include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium borofluoride (LiBF ₄ ), and arsenic hexafluoride. Lithium salts such as lithium (LiAsF ₆ ), lithium trifluorometasulfonate (LiCF ₃ SO ₃ ), lithium bistrifluoromethylsulfonylimide [LiN (CF ₃ SO ₂ ) ₂ ] are included.

  On the other hand, when the secondary battery functions as a nickel metal hydride battery, a nickel cadmium battery, or an air zinc battery, examples of the electrolyte include potassium hydroxide.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the illustrated embodiments.

[Embodiment 1]
FIG. 2 is a cross-sectional view of secondary battery 100 of the first embodiment. As shown in FIG. 2, the secondary battery 100 includes a housing case 110 and an electrode group 120.

  The housing case 110 includes a housing 113 having a housing hole 111 and a sealing member 130. The housing 113 is a conductive member made of, for example, aluminum. The housing 113 has one accommodation hole 111. The electrode group 120 is accommodated in the accommodation hole 111. Further, a positive electrode lead 140 and a negative electrode lead 150 protrude from the electrode group 120 toward the sealing member 130 side.

  FIG. 3 is an exploded perspective view of the electrode group 120. As shown in FIG. 3, the electrode group 120 has a cylindrical shape. The electrode group 120 is formed by winding the laminate 127.

  4 is a cross-sectional view taken along one-dot chain line A of the laminate 127 of FIG. As shown in FIG. 4, the laminate 127 includes a sheet-like positive electrode 121, a sheet-like negative electrode 123, and a sheet-like separator 125. Also. The positive electrode 121 is composed of a positive electrode current collector 121a and a positive electrode mixture layer 121b sandwiching the positive electrode current collector 121a; the negative electrode 123 is composed of a negative electrode current collector 123a and a negative electrode mixture layer 123b sandwiching the negative electrode current collector 123a. Become.

  In this embodiment, it is preferable that the current collector 121 a of the positive electrode 121 is longer than the separator 125 and the negative electrode 123. By making the current collector 121a of the positive electrode 121 longer than the separator 125 and the negative electrode 123 in this way, the outer periphery of the electrode group 120 is not a low-strength mixture layer but a relatively high-strength positive electrode 121 current collector. It can be covered with 121a.

  Next, the positive electrode lead 140 and the negative electrode lead 150 will be described with reference to FIG. 2 again.

  The positive electrode lead 140 protruding from the electrode group 120 is joined to the inner side surface of the housing hole 111 of the housing 113. Moreover, the length L of the area | region which protruded from the electrode group 120 among the positive electrode leads 140 is 1-3 mm, and it is preferable that it is about 2 mm.

  Further, the positive electrode lead 140 is not bent. In this embodiment, since the positive electrode lead 140 is less bent, the positive electrode lead 140 can be prevented from generating heat during use of the secondary battery.

  The negative electrode lead 150 protruding from the electrode group 120 is joined to the electrode terminal (negative electrode terminal) 131 of the sealing member 130.

  The sealing member 130 is a member that closes the accommodation hole 111 of the housing 113. As shown in FIG. 2, the sealing member 130 includes a sealing plate 133 having a through hole and an electrode terminal 131 that passes through the through hole of the sealing plate 133. The electrode terminal 131 is bundled so as to sandwich the edge of the through hole of the sealing plate 133. An insulating member 135 is disposed between the electrode terminal 131 and the plate 133. Thereby, the electrode terminal 131 and the housing | casing 113 are insulated.

  A gap G is formed between the sealing member 130 and the electrode group 120. The positive electrode lead 140 is bonded to the inner surface of the accommodation hole 111 between the sealing member 130 and the electrode group 120.

  Next, a method for manufacturing secondary battery 100 of the present embodiment will be described with reference to FIGS. 5A to 5D.

  The manufacturing method of the secondary battery 100 includes, for example, 1) a first step of preparing the housing 113 (see FIG. 5A), and 2) a second step of inserting the electrode group 120 into the accommodation hole 111 of the housing 113 ( 5B), 3) a third step (see FIG. 5C) for joining the positive electrode lead 140 protruding from the electrode group 120 to the inner surface of the housing hole 111 of the housing 113, and 4) the housing hole 111 by the sealing member 130. And a fourth step (FIG. 5D). Each step will be described below.

  FIG. 5A shows the first step. As shown in FIG. 5A, in the first step, the housing 113 is prepared. The housing 113 may be manufactured by drawing or impact molding, for example.

  FIG. 5B shows the second step. As shown in FIG. 5B, in the second step, the electrode group 120 is inserted into the accommodation hole 111 of the housing 113. The electrode group 120 is inserted into the accommodation hole 111 along the winding axis of the electrode group 120. A positive electrode lead 140 and a negative electrode lead 150 protrude from the electrode group 120. As shown in FIG. 5B, the negative electrode lead 150 may be bonded to the electrode terminal 131 of the sealing member 130 in advance.

  FIG. 5C shows the third step. As shown in FIG. 5C, in the third step, the positive electrode lead 140 protruding from the electrode group 120 is joined to the inner surface of the housing hole 111 of the housing 113.

  In order to join the positive electrode lead 140 to the inner surface of the housing hole 111 of the housing 113, the positive electrode lead 140 may be ultrasonically bonded to the inner surface of the housing hole 111. More specifically, the casing 113 and the positive electrode lead 140 are sandwiched between the horn 160 and the anvil 161 of the ultrasonic head, thereby pressing the positive electrode lead 140 against the inner surface of the accommodation hole 111; By doing so, the positive electrode lead 140 may be joined to the inner surface of the accommodation hole 111.

  As described above, in the present embodiment, since the positive electrode lead 140 is bonded to the inner surface of the accommodation hole 111 by ultrasonic bonding that does not generate a spark that causes a micro short-circuit failure, the occurrence rate of the micro short-circuit failure. Is low. For this reason, a secondary battery with a high output is obtained.

  FIG. 5D shows the fourth step. As shown in FIG. 5D, in the fourth step, the accommodation hole 111 is closed with the sealing member 130. In order to close the accommodation hole 111 with the sealing member 130, the sealing member 130 may be welded to the housing 113. Means for welding the sealing member 130 to the housing 113 include laser welding, heat welding, brazing, pressing, friction welding, and the like.

  In addition, the electrolytic solution is injected into the accommodation hole 111 of the housing 113 between the third step and the fourth step.

[Embodiment 2]
In Embodiment 1, the electrode terminal of the sealing member has been described as having no through hole. In Embodiment 2, a mode in which the electrode terminal of the sealing member has a through hole will be described.

  FIG. 6 is a cross-sectional view of secondary battery 200 of the second embodiment. The same components as those of the secondary battery 100 of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  As shown in FIG. 6, the secondary battery 200 has a sealing member 230. The sealing member 230 has an electrode terminal 231 and a cap 239. The electrode terminal 231 has a through hole 237. A negative electrode lead 150 is joined to the inner surface of the through hole 237.

  The cap 239 is a member that closes the opening on the outside of the through hole 237. The cap 239 prevents the electrolyte in the housing 113 from leaking outside by closing the opening on the outside of the through hole 237. The cap 239 may be bonded to the opening on the outer side of the through hole 237 after closing the housing hole 111 with the sealing member 230 and bonding the negative electrode lead 150 to the inner surface of the through hole 237.

  As described above, in the present embodiment, by forming the through hole 237 in the electrode terminal 231 and joining the negative electrode lead 150 to the inner surface of the through hole 237, the bending of the negative electrode lead 150 can be reduced. Thereby, in addition to the effects of the first embodiment, it is possible to prevent the negative electrode lead 150 from generating heat during use of the secondary battery.

[Embodiment 3]
In Embodiments 1 and 2, the case where the housing has one accommodation hole has been described. In Embodiment 3, the case where the housing has a plurality of receiving holes will be described.

  FIG. 7 is a cross-sectional view of secondary battery 300 of the third embodiment. As shown in FIG. 7, the secondary battery 300 includes a housing case 310 and an electrode group 120.

  The housing case 310 includes a housing 313 having a plurality of housing holes 111. The electrode group 120 is accommodated in each accommodation hole 111. Thus, in the present embodiment, the housing case 310 houses the plurality of electrode groups 120.

  The housing 313 has a bottom plate 311. Such a housing | casing 313 is formed by joining the baseplate 311 to the side part which has a through-hole. The bottom plate 311 may be formed with an explosion-proof valve.

  The positive electrode lead 140 protruding from the electrode group 120 is joined to the inner surface of the accommodation hole 111. Further, the negative electrode lead 150 protruding from the electrode group 120 is joined to the inner surface of the through hole 237 of the electrode terminal 231.

  Thus, by accommodating a plurality of electrode groups in one accommodation case, in addition to the effects of the first embodiment, a secondary battery having a larger capacity can be provided.

  Since the secondary battery of the present invention generates little heat and has a high output, it can be suitably used as a secondary battery for vehicles such as an electric vehicle, a backup secondary battery for electronic equipment, and a secondary battery for home use.

100, 200, 300 Secondary battery 110, 310 Housing case 111 Housing hole 113, 313 Housing 120 Electrode group 121 Positive electrode 121a Positive electrode current collector 121b Positive electrode mixture layer 123 Negative electrode 123a Negative electrode collector 123b Negative electrode mixture layer 125 Separator 130, 230 Sealing member 131, 231 Electrode terminal 133 Sealing plate 135 Insulating member 140 Positive electrode lead 150 Negative electrode lead 160 Horn 161 Anvil 237 Through hole 239 Cap 311 Bottom plate

Claims (7)

An electrode group having a positive electrode and a negative electrode, a wound product of a laminate of the positive electrode and the separator sandwiched between the negative electrode, a positive electrode lead connected to the positive electrode, and a negative electrode lead connected to the negative electrode; ,
A conductive housing case having a housing hole for housing the electrode group and a casing having a bottom surface intersecting with a winding axis of the electrode group, and a sealing member for closing the housing hole and having an electrode terminal;
A secondary battery having
One of the positive electrode lead and the negative electrode lead is joined to the inner surface of the accommodation hole,
The other is a secondary battery joined to the electrode terminal.   The secondary battery according to claim 1, wherein the positive electrode lead or the negative electrode lead joined to the inner surface of the accommodation hole protrudes from the vicinity of the outer periphery of the electrode group.   The positive electrode lead or the negative electrode lead bonded to the inner surface of the housing hole protrudes from the electrode group toward the sealing member, and is bonded to the inner surface of the housing hole between the electrode group and the sealing member. The secondary battery according to claim 1. The sealing member further includes a sealing plate having a through hole through which the electrode terminal passes,
The secondary battery according to claim 3, wherein the electrode terminal has a constriction so as to sandwich the through hole. The positive electrode lead is bonded to the inner surface of the accommodation hole;
The secondary battery according to claim 1, wherein the housing includes aluminum. A method for manufacturing the secondary battery according to claim 1, comprising:
Preparing a housing having the accommodation hole;
Inserting the electrode group into the receiving hole;
Bonding the positive electrode lead or the negative electrode lead to the inner surface of the accommodation hole;
Closing the accommodation hole with the sealing member;
A method for producing a secondary battery, comprising: The method of manufacturing a secondary battery according to claim 6, wherein the positive electrode lead or the negative electrode lead is bonded to the inner surface of the accommodation hole by wedge bonding, stirring bonding, or ultrasonic bonding.

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