JP2012124009A - Secondary battery and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a secondary battery capable of promptly impregnating an electrode group with an electrolytic solution.SOLUTION: A manufacturing method of a secondary battery comprises: a step of preparing a housing having a housing hole; a step of inserting an electrode group into the housing hole; a step of setting a sealing member without a cap in the housing hole and passing either of a positive electrode lead and a negative electrode lead through a cylinder of an electrode terminal; a step of bonding the either of the positive electrode lead and negative electrode lead to an inner surface of the cylinder of the electrode terminal; a step of setting an electrolyte solution injection member in the electrode terminal and bringing an adhesion part into tight contact with a flange; a step of reducing the pressure in the housing hole by exhausting air in the housing hole through a pressure reducing path; a step of impregnating the electrode group in the housing hole with the electrolytic solution by injecting the electrolytic solution into the housing hole through an injection path; and a step of blocking an opening on an external side of the secondary battery of the cylinder by bonding the cap to the flange.

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 a secondary battery is characterized by having a high electromotive force of 3 to 4 V, and its excellent performance has attracted attention.

  A manufacturing method of such a secondary battery includes: winding a laminate composed of a sheet-like positive electrode and a negative electrode and a sheet-like separator disposed between the positive electrode and the negative electrode in a spiral shape to form an electrode group; A step of housing the electrode group in the case; a step of joining a lead protruding from one electrode of the electrode group to the bottom of the case; and a step of injecting an electrolyte into the case (see, for example, Patent Document 1) Bonding a lead protruding from the other electrode of the electrode group to the sealing member; and attaching the sealing member to the opening of the housing.

  FIG. 1 shows a method of injecting an electrolytic solution into a casing disclosed in Patent Document 1. In the method disclosed in Patent Document 1, the step of setting the funnel member 4 having the pressure adjusting port 3 to the housing 1 in which the electrode group 7 is accommodated, and adjusting the pressure of the funnel member 4 using the air in the housing 1. Evacuating from the mouth 3 and depressurizing the inside of the housing 1, injecting the electrolyte from the funnel member 4 into the housing 1 while standing the tilted housing 1, and infiltrating the electrolyte into the electrode group 7. (FIG. 1).

  In addition, ultrasonic bonding is known as a technique for bonding a lead protruding from an electrode group to a sealing member (see, for example, Patent Document 2).

JP-A-11-126597 Japanese Patent Laid-Open No. 06-187968

  However, in the method as disclosed in Patent Document 1, the adhesiveness of the joint portion between the funnel member and the housing is not sufficient, and air is released from the joint portion between the funnel member and the housing into the decompressed housing. Sometimes flowed in. For this reason, the inside of the housing could not be sufficiently depressurized. If the pressure inside the casing is not sufficient, it may take time for the electrolyte to penetrate, or it may be necessary to repeatedly reduce the pressure in the casing during the process of injecting the electrolyte. If the pressure inside the casing is repeatedly reduced during the process of injecting the electrolyte, the electrolyte already injected into the casing may evaporate. Moreover, if the adhesiveness of the junction between the funnel member and the casing is not sufficient, the electrolyte solution may leak out from the junction between the funnel member and the casing.

  Further, as disclosed in Patent Document 1, in the method of injecting the electrolytic solution into the housing before the electrode lead is joined to the sealing member, the electrode lead may be wetted with the electrolytic solution and the electrode lead may be denatured. is there. It becomes difficult to join the modified electrode lead to the electrode terminal. For this reason, as disclosed in Permitted Document 1, in the method of injecting the electrolytic solution into the housing before the electrode lead is joined to the sealing member, the reliability of joining the electrode lead and the electrode terminal is low. .

  A first object of the present invention is to provide a method for manufacturing a secondary battery that can rapidly infiltrate an electrolyte solution into an electrode group. A second object of the present invention is to prevent the electrode lead from being modified by the electrolytic solution before being joined to the sealing member.

The first of the present invention relates to the secondary battery shown below.
[1] An electrode group having 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 A housing case having a housing hole for housing the electrode group and a bottom surface intersecting a winding axis of the electrode group, and a sealing case for closing the housing hole. The sealing member includes a sealing plate having a through hole, a bottomless cylinder having an axis along the winding axis of the electrode group and straddling the through hole of the sealing plate, and an end of the cylindrical body An electrode terminal having a flange at the outer end of the secondary battery, and a cap joined to the flange and closing an opening on the outside of the secondary battery of the cylindrical body, and the positive electrode lead and One of the negative electrode leads is the cylindrical body It is joined to the inner surface, the secondary battery.
[2] The secondary battery according to [1], wherein a width of a flange seal surface of the flange is 0.5 to 5 mm.
[3] The secondary battery according to [1] or [2], wherein one of the positive electrode lead and the negative electrode lead is joined to an inner surface of the cylindrical body between the cap and the sealing plate.
[4] The positive electrode lead or the negative electrode lead joined to the inner side surface of the cylindrical body protrudes from the electrode group, and the positive electrode lead or the negative electrode lead joined from the electrode group to the inner side surface of the cylindrical body. The protruding position is the secondary battery according to any one of [1] to [3], wherein the protruding position overlaps the opening of the cylindrical body along the winding axis.
[5] The secondary battery according to any one of [1] to [4], wherein the cylindrical body of the electrode terminal is bundled so as to sandwich an edge of the through hole of the sealing plate.

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. Inserting the sealing member without the cap into the accommodation hole, and passing one of the positive electrode lead and the negative electrode lead through the cylindrical body of the electrode terminal, and the positive electrode lead and the negative electrode lead. One of the electrode terminal and the inner surface of the cylindrical body of the electrode terminal, an injection path for injecting an electrolyte into the accommodation hole, a decompression path for exhausting air from the accommodation hole, and a close contact with the flange A step of setting an electrolyte injection member having a contact portion on the electrode terminal, and closely contacting the contact portion with the flange; and exhausting the air in the accommodation hole from the decompression path to decompress the interior of the accommodation hole. A step of injecting an electrolyte solution into the accommodation hole from the injection path and infiltrating the electrolyte solution into an electrode group in the accommodation hole; and joining the cap to the flange; And a step of closing the opening on the outside.
[7] The method for manufacturing a secondary battery according to [6], wherein in the step of reducing the pressure of the housing hole, the air pressure in the housing hole is set to 100 Torr or less.
[8] The method for manufacturing a secondary battery according to [6] or [7], wherein a contact surface of the contact portion with the flange is formed of an elastic member.

  According to the method for manufacturing a secondary battery of the present invention, the electrolyte solution can be rapidly infiltrated into the electrode group in a short time, so that the injection rate of the electrolyte solution can be increased and the time of the electrolyte solution injection step can be reduced. it can. Further, according to the method for manufacturing a secondary battery of the present invention, the electrode lead is not denatured by the electrolytic solution before being joined to the sealing member.

The figure which shows a part of manufacturing method of the secondary battery disclosed by patent document 1 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. 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.

1. Secondary Battery of the Present Invention The secondary battery of the present invention has an electrode group and a housing case that houses 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 has 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 partially or entirely conductive so that electricity can be taken out. 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.

  It is preferable that at least a part of the housing is a conductor. Examples of such housing materials include aluminum, magnesium, iron, nickel, carbon, copper, and alloys thereof. Further, as described later, it is preferable that one of a positive electrode lead and a negative electrode lead is bonded to the housing, and the material of the housing depends on whether a positive electrode lead or a negative electrode lead described later is bonded to the housing. It is selected appropriately. 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 sealing member has a sealing plate, an electrode terminal, and a cap. The sealing plate is a plate-like member having a through hole. The sealing plate closes the housing hole of the housing by joining to the housing. The sealing plate may be conductive or non-conductive.

  The electrode terminal is a conductive member having a bottomless cylindrical body and a flange. The cylinder straddles the through hole of the sealing plate. One of a positive electrode lead and a negative electrode lead, which will be described later, is joined to the inner side surface of the cylinder of the electrode terminal. Therefore, the electrode terminal functions as a positive electrode or a negative electrode terminal.

  The flange is provided at the outer end of the secondary battery of the cylindrical body. A flange is an area | region joined to a cap among electrode terminals. The width of the surface joined to the flange cap (hereinafter also referred to as “flange seal surface”) is preferably 0.5 to 5 mm. Thus, in this invention, the flange for joining with a cap to an electrode terminal can be provided, and joining of a cap and an electrode terminal can be strengthened.

  The material of the electrode terminal (cylinder and flange) is appropriately selected depending on whether the electrode terminal functions as a positive terminal or a negative 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 present invention is characterized in that either one of the positive electrode lead and the negative electrode lead is joined to the inner surface of the cylindrical body.

  The cap is a conductive plate that closes the opening of the cylinder of the electrode terminal. More specifically, the cap closes the opening outside the secondary battery among the openings of the cylindrical body of the electrode terminal by joining to the flange of the electrode terminal. In this manner, the cap blocks the opening of the cylindrical body of the electrode terminal, thereby preventing the electrolytic solution accommodated in the accommodation hole from leaking. As described above, in the present invention, since the reliability of the coupling between the cap and the flange of the electrode terminal is high, it is possible to reliably prevent the electrolytic solution accommodated in the accommodation hole from leaking.

  Although the structure of a sealing member is not specifically limited, It is preferable that the cylinder of 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, the cylindrical body sandwiches the edge of the through hole of the sealing plate, so that the electrolytic solution is difficult to leak from between the sealing plate and the cylindrical body of the electrode terminal, and the electrolytic solution can be prevented from leaking from the accommodation hole. .

  Moreover, since the cylindrical body of the electrode terminal straddles the through hole of the sealing plate, a gap is formed between the sealing plate and the electrode group and between the sealing plate and the cap (see FIG. 2).

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 contained in the positive electrode mixture layer 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 that protrude from the electrode group along the winding axis of 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 is preferably, for example, a strip shape (see FIG. 3).

  As described above, the present invention is characterized in that the electrode lead (positive electrode lead or negative electrode lead) bonded to the electrode terminal is bonded to the inner surface of the cylindrical body of the electrode terminal. With this configuration, after setting the sealing member having no cap in the accommodation hole, one of the positive electrode lead and the negative electrode lead can be joined to the inner surface of the cylindrical body of the electrode terminal (see FIG. 5D). As described above, in the present invention, after the accommodation hole is closed with the sealing member, one of the positive electrode lead and the negative electrode lead can be bonded to the inner side surface of the cylindrical body of the electrode terminal. (Hereinafter also referred to as “terminal bonding lead”) can be shortened, and the bending of the terminal bonding lead can be reduced (see FIG. 2).

  Here, “the bending of the terminal coupling lead is small” means that the terminal coupling lead is not bent at all, or the radius of curvature of the bent portion of the terminal coupling lead is equal to or greater than the plate thickness of the terminal coupling lead. For example, when the plate thickness of the terminal coupling lead is 0.15 mm, the radius of curvature of the terminal coupling lead 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 preferable that the protruding position of the terminal bonding lead overlaps the opening of the cylindrical body along the winding axis of the electrode group. By overlapping the protruding position of the terminal bonding lead over the opening of the cylindrical body of the electrode terminal, the bending of the terminal bonding lead can be further reduced (see FIG. 2).

  On the other hand, the other of the positive electrode lead and the negative electrode lead that is not bonded to the electrode terminal is preferably bonded to the housing. A positive electrode lead or a negative electrode lead (hereinafter also referred to as a “casing bonding lead”) bonded to the housing may be coupled to the inner side surface of the housing accommodation hole (see FIG. 2) or may be bonded to the bottom surface. Good.

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.

2. The secondary battery manufacturing method of the present invention includes, for example, 1) a first step of preparing a housing, and 2) inserting an electrode group into a housing hole of the housing. 2 steps, 3) a third step in which a sealing member without a cap is set in the accommodation hole, 4) a fourth step in which the terminal joining lead is joined to the inner surface of the cylindrical body of the electrode terminal, and 5) electrolysis. A fifth step of setting the liquid injection member on the electrode terminal, 6) a sixth step of reducing the pressure in the accommodation hole, 7) a seventh step of injecting the electrolyte into the accommodation hole, and 8) a cylinder of the electrode terminal with the cap. And an eighth step of closing the opening on the outside of the secondary battery. Hereinafter, each step will be described.

  1) In the first step, a housing is prepared. 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 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).

  2) In the second step, the electrode group is inserted into the housing hole of the housing. In order to insert the electrode group into the housing hole of the housing, the electrode group may be inserted into the housing hole along the winding axis of the electrode group.

  3) In the third step, a sealing member having no cap is set in the accommodation hole. Specifically, the sealing plate of the sealing member is joined to the housing. In this step, the sealing member is set in the accommodation hole so that the terminal joining lead passes through the cylindrical body of the electrode terminal.

  4) In the fourth step, the terminal joining lead that passes through the cylindrical body is bonded to the inner surface of the cylindrical body. The method for joining the terminal joining lead to the inner surface of the cylindrical body of the electrode terminal is not particularly limited, but wedge bonding, stirring joining or ultrasonic joining is preferable. This is because when a terminal bonding lead is bonded by wedge bonding, stir bonding, or ultrasonic bonding, a spark that causes a micro short circuit failure (OCV failure) does not occur.

  Further, when the terminal bonding lead is ultrasonically bonded to the inner surface of the electrode terminal cylinder, the terminal bonding lead is bonded to the inner surface of the cylinder between the cap and the sealing plate (see FIG. 5D).

  Further, if the terminal joining lead is joined to the electrode terminal before the electrolytic solution is injected into the accommodation hole, the terminal joining lead is not denatured by the electrolyte before the terminal joining lead is joined to the electrode terminal. For this reason, if the terminal bonding lead is bonded to the electrode terminal before the electrolyte is injected into the accommodation hole, the reliability of bonding between the terminal bonding lead and the electrode terminal is increased. Therefore, in the present invention, it is preferable that the fourth step of bonding the terminal bonding lead to the inner surface of the electrode terminal cylinder is performed before the fifth step of setting the electrolyte injection member to the electrode terminal. The fourth step may be performed after the seventh step of injecting the electrolytic solution.

  In the present invention, since the terminal joining lead can be joined to the inner side surface of the cylindrical body of the electrode terminal after the sealing member having no cap is set in the accommodation hole, the terminal joining lead is shortened and the terminal joining lead is provided. Can be reduced (see FIG. 2).

  5) In the fifth step, the electrolyte injection member is set on the electrode terminal. The electrolyte solution injection member includes an injection path for injecting the electrolyte solution into the accommodation hole, a decompression path for exhausting air from the accommodation hole, and a close contact portion that is in close contact with the flange of the electrode terminal. In order to set the electrolyte injection member to the electrode terminal, the contact portion of the electrolyte injection member may be brought into close contact with the flange of the electrode terminal. In order to ensure the close contact between the close contact portion and the flange, the flange and the contact surface of the close contact portion may be made of an elastic member such as rubber, for example. Thus, by setting the electrolytic solution injection member to the electrode terminal, the injection path and the decompression path communicate with the accommodation hole through the cylindrical body of the electrode terminal. Moreover, the space which consists of an accommodation hole, a cylinder, a pressure reduction path | pass, and an injection | pouring path | pass is sealed by closely_contact | adhering the contact | adherence part of an electrolyte injection member to the flange of an electrode terminal.

  6) In the sixth step, the inside of the accommodation hole is depressurized. In order to decompress the inside of the accommodation hole, the air in the accommodation hole may be exhausted through the decompression path of the electrolyte injection member. As described above, in the present invention, the space formed by the accommodation hole, the cylindrical body, the decompression path, and the injection path is sealed by bringing the contact portion of the electrolyte injection member into close contact with the flange. Difficult to flow into the hole. Thereby, the atmospheric | air pressure in an accommodation hole can be 100 Torr or less. For example, the pressure in the accommodation hole after decompression is 10 to 100 Torr, which is about 50 Torr.

  7) In the seventh step, an electrolytic solution is injected into the accommodation hole, and the electrolytic solution is permeated into the electrode group accommodated in the accommodation hole. The electrolytic solution is injected into the accommodation hole through the injection path of the electrolytic solution injection member. As described above, since the atmospheric pressure in the accommodation hole is kept extremely low, the electrolytic solution can quickly penetrate into the electrode group in the accommodation hole. Therefore, in the present invention, it is possible to quickly inject a necessary amount of electrolyte into the accommodation hole.

  Further, as described above, the space composed of the accommodation hole, the cylinder, the decompression path, and the injection path is sealed by the close contact portion and the flange of the electrolyte injection member, so that the external space is provided in the decompressed accommodation hole. Air will not flow in. For this reason, the atmospheric pressure in the accommodation hole during the injection of the electrolyte does not increase, and there is no need to repeatedly reduce the pressure in the accommodation hole. Further, the space composed of the accommodation hole, the cylinder, the decompression path, and the injection path is sealed by the contact portion and the flange of the electrolyte injection member, so that the electrolyte does not leak outside.

  8) In the eighth step, the opening on the outside of the secondary battery of the cylindrical electrode terminal is closed with a cap. To close the opening of the electrode terminal with the cap, the cap may be joined to the flange of the electrode terminal. Means for joining the cap to the flange include laser welding, thermal welding, brazing, pressing, friction welding, and the like. Thus, in this invention, since a cap is joined to the flange of an electrode terminal, the reliability of joining with a cap and an electrode terminal is high, and electrolyte solution does not leak easily.

  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]
In the first embodiment, a mode in which the terminal coupling lead is a negative electrode lead will be described.

  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.

  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 134, a cap 139, and an electrode terminal 131. The electrode terminal 131 has a bottomless cylinder 131a straddling the through-hole 134 of the sealing plate, and a flange 131b provided at the outer end of the secondary battery of the cylinder 131a. A negative electrode lead 150 is joined to the inner surface of the cylindrical body 131a. The width W of the flange seal surface of the flange 131b is, for example, 0.5 to 5 mm.

  Further, the cylindrical body 131 a of the electrode terminal 131 is wrapped so as to sandwich the edge of the through hole 134 of the sealing plate 133. The constriction 132 of the cylindrical body 131 a is surrounded by the sealing plate 133. Further, an insulating member 135 is disposed between the cylinder 131a and the plate 133. Thereby, the electrode terminal 131 and the housing | casing 113 are insulated.

  The cap 139 is a member that closes the outer opening of the secondary battery of the cylindrical body 131a. The cap 139 is joined to the flange 131b of the electrode terminal 131 to close the opening of the cylindrical body 131a outside the secondary battery. Since the cap 139 closes the cylindrical body, the electrolytic solution in the housing 113 is prevented from leaking outside.

  Gaps are formed between the sealing plate 133 and the electrode group 120 and between the sealing plate 133 and the cap 139.

  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 includes a wound product of the laminate 127. Further, a positive electrode lead 140 and a negative electrode lead 150 protrude from the electrode group 120 toward the sealing member 130 side. The length 150L of the region of the negative electrode lead 150 protruding from the electrode group 120 is, for example, 6 to 15 mm.

  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. The positive electrode 121 includes a positive electrode current collector 121a and a positive electrode mixture layer 121b that sandwiches the positive electrode current collector 121a; the negative electrode 123 includes a negative electrode current collector 123a and a negative electrode mixture layer 123b that sandwiches the negative electrode current collector 123a. Consists of.

  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.

  The negative electrode lead 150 protruding from the electrode group 120 is joined to the inner surface of the cylinder 131 a of the electrode terminal 131. The protruding position of the negative electrode lead 150 overlaps the opening of the cylinder 131 a of the electrode terminal 131 along the winding axis of the electrode group 120. Further, the negative electrode lead 150 is joined to the inner side surface of the cylindrical body 131 a between the sealing plate 133 and the cap 139.

  As described above, in the present embodiment, since the negative electrode lead 150 is less bent, the negative electrode lead 150 can be prevented from generating heat during use of the secondary battery.

  Next, a method for manufacturing secondary battery 100 of the present embodiment will be described with reference to FIGS. 5A to 5D and FIGS. 6A to 6C.

  The manufacturing method of the secondary battery 100 includes, for example, 1) a first step of preparing the housing 113 (FIG. 5A), and 2) a second step of inserting the electrode group 120 into the accommodation hole 111 of the housing 113 (FIG. 5B). 3) A third step (FIG. 5C) for setting the sealing member 130 without the cap 139 in the accommodation hole 111, and 4) a fourth step for joining the negative electrode lead 150 to the inner surface of the cylindrical body 131a (FIG. 5D), 5) a fifth step (FIG. 6A) for setting the electrolyte injection member 170 to the electrode terminal 131, 6) a sixth step (FIG. 6A) for depressurizing the interior of the accommodation hole 111, and 7) an accommodation hole. A seventh step (FIG. 6B) for injecting the electrolytic solution 177 into 111; 8) an eighth step for removing the electrolytic injection member 170 from the electrode terminal 131; and 9) an external side of the secondary battery of the cylinder 131a with the cap 139. To close the opening of the A step (FIG. 6C), the.

  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.

  FIG. 5C shows the third step. As shown in FIG. 5C, in the third step, the sealing member 130 without the cap 139 is set in the accommodation hole 111. More specifically, the sealing member 130 without the cap 139 is set in the accommodation hole 111 so that the negative electrode lead 150 passes through the cylindrical body 131a.

  Further, the positive electrode lead 140 protruding from the electrode group 120 between the second step and the third step may be bonded to the inner surface of the housing hole 111 of the housing 113 by, for example, ultrasonic bonding.

  FIG. 5D shows the fourth step. As shown in FIG. 5D, in the fourth step, the negative electrode lead 150 is joined to the inner surface of the cylindrical body 131 a of the electrode terminal 131.

  In order to join the negative electrode lead 150 to the inner surface of the cylinder 131a, the negative electrode lead 150 may be ultrasonically bonded to the inner surface of the cylinder 131a. More specifically, a region protruding from the sealing plate 133 and the negative electrode lead 150 in the cylindrical body 131a are sandwiched between the horn 160 and the anvil 161 of the ultrasonic head, whereby the negative electrode lead 150 is connected to the cylindrical body 131a. The negative electrode lead 150 may be bonded to the inner surface of the cylinder 131a by pressing against the inner surface; and vibrating the horn 160.

  As shown in FIG. 5D, the horn 160 and the anvil 161 of the ultrasonic head cannot sandwich the cylinder 131 a closer to the electrode group 120 than the sealing plate 133 because the sealing plate 133 becomes an obstacle. For this reason, when the negative electrode lead 150 is bonded to the cylinder 131a by ultrasonic bonding, the negative electrode lead 150 is bonded to the inner surface of the cylinder 131a protruding from the sealing plate 133 to the outside of the secondary battery.

  As described above, in the present embodiment, since the negative electrode lead 150 is joined to the electrode terminal 131 before the electrolyte is injected into the accommodation hole 111, the negative electrode lead 150 is joined to the electrode terminal 131 before the negative electrode lead 150 is joined. The lead 150 is not modified by the electrolytic solution.

  In the present embodiment, the negative electrode lead 150 can be shortened because the negative electrode lead 150 is joined to the inner surface of the cylindrical body 131a after the sealing member 130 closes the housing hole 111. By thus shortening the negative electrode lead 150, the bending of the negative electrode lead 150 can be reduced.

  In the present embodiment, since the negative electrode lead 150 is bonded to the inner surface of the cylinder 131a 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. 6A shows the fifth step. As shown in FIG. 6A, in the fifth step, the electrolyte solution injection member 170 is set on the electrode terminal 131. The electrolyte injection member 170 includes an injection path 171, a decompression path 173, and a close contact portion 175. The injection path 171 is a flow path for injecting the electrolytic solution into the accommodation hole 111. The decompression path 173 is a flow path for exhausting air from the accommodation hole 111. The contact portion 175 is a portion that is in close contact with the flange 131 b of the electrode terminal 131.

  In order to set the electrolyte injection member 170 to the electrode terminal 131, the contact portion 175 of the electrolyte injection member 170 is brought into close contact with the flange 131b. As described above, in this embodiment, a part of the electrolyte solution injection member 170 is brought into close contact with the flange 131b, so that the space including the accommodation hole 111, the cylinder body 131a, the injection path 171 and the decompression path 173 is sealed. .

  In addition, by setting the electrolyte injection member 170 to the electrode terminal 131, the injection path 171 and the decompression path 173 of the electrolyte injection member 170 communicate with the accommodation hole via the cylindrical body 131a.

  In the sixth step, the inside of the accommodation hole 111 is depressurized. In order to decompress the inside of the accommodation hole 111, the inside of the accommodation hole 111 may be exhausted from the decompression path 173 of the electrolyte injection member 170. As described above, in this embodiment, since the sealing property of the contact portion between the electrolyte solution injection member 170 and the electrode terminal 131 is high, air is introduced into the accommodation hole 111 from the contact portion between the electrolyte solution injection member 170 and the electrode terminal 131. Is less likely to enter. As a result, in the present embodiment, the atmospheric pressure in the accommodation hole 111 can be set to 100 Torr or less.

  FIG. 6B shows the seventh step. As shown in FIG. 6B, in the seventh step, the electrolytic solution 177 is injected into the accommodation hole 111. In order to inject the electrolyte 177 into the accommodation hole 111, the electrolyte 177 is injected into the accommodation hole 111 through the injection path 171 of the electrolyte injection member 170. As described above, since the space including the accommodation hole 111, the cylinder 131a, the injection path 171 and the decompression path 173 is sealed from the outside, air flows into the decompressed accommodation hole 111 from the outside. There is no. For this reason, the air pressure in the accommodation hole 111 during the injection of the electrolytic solution 177 does not increase, and there is no need to repeatedly reduce the pressure in the accommodation hole 111.

  In the eighth step, the electrolyte solution injection member 170 is removed from the electrode terminal 131.

  FIG. 6C shows the ninth step. As shown in FIG. 6C, in the ninth step, the cap 139 closes the opening of the cylindrical body 131a of the electrode terminal 131 outside the secondary battery. In order to close the opening of the cylindrical body 131 a of the electrode terminal 131 with the cap 139, the cap 139 may be joined to the flange 131 b of the electrode terminal 131.

[Embodiment 2]
In the first embodiment, the form in which a part of the terminal bonding lead (the negative electrode lead 150) is bent has been described. In the second embodiment, a mode in which the terminal bonding lead (negative electrode lead 150) does not have a bend will be described.

  FIG. 7 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. 7, the sealing member 230 of the secondary battery 200 has an electrode terminal 231. The electrode terminal 231 has a cylindrical body 231a and a flange 131b. The cylindrical body 231a has a region 232 having the same inner diameter as the constriction 132 surrounded by the sealing plate between the cap 139 and the sealing plate 133.

  Thus, by providing the region 232 having the same inner diameter as the constriction 132 in the cylindrical body 231a of the electrode terminal 231 between the cap 139 and the sealing plate 133, the negative electrode lead 150 is joined to the electrode terminal 231 without bending. Can.

  As described above, in this embodiment, since the bending of the terminal joint lead is further smaller than that in the first embodiment, in addition to the effects of the first embodiment, the negative electrode lead 150 generates heat during use of the secondary battery. It can prevent more effectively.

[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. 8 is a cross-sectional view of secondary battery 300 of the third embodiment. As shown in FIG. 8, 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.

  In the present embodiment, the caps of the sealing members 130 are connected to form a connection cap 339. As described above, the caps of the sealing members 130 are connected to form the connection cap 339, so that the process of closing the opening of the electrode terminal 131 (cylinder 131a) of each sealing member 130 can be simplified.

  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 131a, 231a Tube 131b Flange 133 Sealing plate 134 Through hole 135 Insulating member 139 Cap 140 Positive electrode lead 150 Negative electrode lead 160 Horn 161 Anvil 170 Electrolyte injection member 171 Injection path 173 Decompression path 175 Adhering part 177 Electrolytic solution 339 Connection cap

Claims (8)

An electrode group having 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;
A housing case having a housing hole for housing the electrode group and a casing having a bottom surface intersecting a winding axis of the electrode group, and a sealing member for closing the housing hole;
A secondary battery having
The sealing member is
A sealing plate having a through hole;
An electrode having a flange at the outer end of the secondary battery among the endless portion of the cylindrical body and the end of the cylindrical body that has an axis along the winding axis of the electrode group and straddling the through hole of the sealing plate A terminal,
A cap that is joined to the flange and closes an opening on the outside of the secondary battery of the cylindrical body,
One of the said positive electrode lead and the said negative electrode lead is a secondary battery joined to the inner surface of the said cylinder.   The secondary battery according to claim 1, wherein a width of a flange seal surface of the flange is 0.5 to 5 mm.   2. The secondary battery according to claim 1, wherein one of the positive electrode lead and the negative electrode lead is bonded to an inner surface of the cylindrical body between the cap and the sealing plate. The positive electrode lead or the negative electrode lead joined to the inner surface of the cylindrical body protrudes from the electrode group,
The position where the said positive electrode lead or the said negative electrode lead joined to the inner surface of the said cylindrical body from the said electrode group overlaps with the opening part of the said cylindrical body along the said winding axis | shaft. Secondary battery.   The secondary battery according to claim 1, wherein the cylindrical body of the electrode terminal is bundled so as to sandwich an edge of the through hole of the sealing plate. 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;
Setting the sealing member without the cap in the accommodation hole, and passing one of the positive electrode lead and the negative electrode lead through the cylindrical body of the electrode terminal;
Bonding one of the positive electrode lead and the negative electrode lead to the inner surface of the cylindrical body of the electrode terminal;
An electrolyte solution injection member having an injection path for injecting an electrolyte solution into the accommodation hole, a decompression path for exhausting air from the accommodation hole, and a close contact portion in close contact with the flange is set on the electrode terminal, and the close contact Attaching the part to the flange;
Exhausting the air in the accommodation hole from the decompression path, and reducing the pressure in the accommodation hole;
Injecting an electrolyte from the injection path into the accommodation hole, and infiltrating the electrolyte into an electrode group in the accommodation hole;
Joining the cap to the flange, and closing an opening of the cylindrical body on the outside of the secondary battery.   The method for manufacturing a secondary battery according to claim 6, wherein, in the step of reducing the pressure of the accommodation hole, the atmospheric pressure in the accommodation hole is set to 100 Torr or less. The method for manufacturing a secondary battery according to claim 6, wherein a contact surface of the contact portion with the flange is formed of an elastic member.

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