JP2024002692A - secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new battery structure from the viewpoint of battery sealing and terminal installation.

SOLUTION: A secondary battery is provided which is composed of an electrode assembly and an exterior body that stores the electrode assembly. In such a secondary battery, an electrode terminal 200 provided on an exterior body opening 150 of an exterior body 100 includes a sealing member 300 for sealing the exterior body. A main surface of the sealing member located on the inside of the exterior body is smaller than the exterior body opening. The sealing member that seals the exterior body opening is a deformable member that can be deformed by pressing force.

SELECTED DRAWING: Figure 3

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to secondary batteries. In particular, the present invention relates to a secondary battery equipped with an electrode assembly consisting of electrode constituent layers including a positive electrode, a negative electrode, and a separator.

Secondary batteries are so-called storage batteries, so they can be repeatedly charged and discharged, and are used for various purposes. For example, secondary batteries are used in mobile devices such as mobile phones, smartphones, and notebook computers.

Patent No. 2748539 Japanese Patent Application Publication No. 2005-190688 JP 2019-87477 Publication Patent No. 4605823 Patent No. 5551781 Japanese Patent Application Publication No. 9-167605 JP2018-85178A

Secondary batteries generally use a liquid electrolyte as a medium for ion movement that contributes to charging and discharging. In other words, so-called electrolytes are used in secondary batteries. In such a secondary battery, it is necessary to seal the battery in order to prevent leakage of electrolyte and gas generated within the battery.

On the other hand, in order to use a secondary battery, it is necessary to provide an external terminal for electrical connection with the outside.

The inventors of the present application have conducted extensive studies to see if there is still room for the development of a battery structure that can satisfy both the requirements of hermetically sealed batteries and the provision of external terminals. As a result, it was found that there is still room for development of a battery structure that satisfies both the hermetic sealing of the battery and the installation of external terminals.

The present invention has been made in view of the above problems. That is, the main object of the present invention is to provide a new battery structure from the viewpoint of battery sealing and terminal installation.

The inventors of the present application attempted to solve the above-mentioned problems by tackling the problem in a new direction rather than by extending the conventional technology. As a result, a secondary battery was invented that achieved the above main objective.

A secondary battery according to the present invention includes an electrode assembly and an exterior body housing the electrode assembly,
an electrode terminal provided in an opening of the exterior body includes a sealing member for sealing the exterior body;
The main surface of the sealing member located inside the exterior body is smaller than the exterior body opening, and the sealing member that closes the exterior body opening is a deformable member that can be deformed due to a pressing force. ing.

In the secondary battery according to the present invention, the safety function is suitably performed because the battery configuration in which both the battery sealing and the external terminal installation are involved is an unprecedented configuration. More specifically, when the internal pressure of the cell increases abnormally, the sealing member, which is a separate member different from the electrode terminal, changes its shape and allows the gas inside the exterior body to be released. This can prevent more serious accidents such as unintentional battery explosions.

FIG. 1 is a cross-sectional view schematically showing electrode constituent layers (FIG. 1(A): plane layered structure, FIG. 1(B): wound structure). FIG. 2 is a schematic diagram of a secondary battery according to an embodiment of the present invention (FIG. 2(A): sectional view, FIG. 2(B): half-divided perspective view). FIG. 3 is a schematic diagram showing a configuration related to the opening of the outer case of a secondary battery according to an embodiment of the present invention. FIG. 4 is a schematic cross-sectional view showing the relationship between the sealing member and the opening of the outer case in a secondary battery according to an embodiment of the present invention. FIG. 5 is a schematic diagram showing typical elements constituting a secondary battery according to an embodiment of the present invention. FIG. 6 is a schematic perspective view and a sectional view showing the sealing member. FIG. 7 is a schematic diagram showing a configuration related to the opening of the outer case of a secondary battery according to an embodiment of the present invention. FIG. 8 is a schematic cross-sectional view for explaining the sealing of the opening edge of the outer case in the secondary battery according to an embodiment of the present invention. FIG. 9 is a schematic diagram for explaining the safety function of a secondary battery according to an embodiment of the present invention. FIG. 10 is a schematic diagram for explaining the safety function of a secondary battery according to an embodiment of the present invention. FIG. 11 is a schematic perspective sectional view for explaining the deformation of the sealing member when the cell internal pressure abnormally increases. FIG. 12 is a schematic perspective sectional view for explaining the sharp edge of the opening edge of the exterior body. FIG. 13 is a schematic perspective sectional view for explaining the deformation of the sealing member during installation. FIG. 14 is a schematic diagram for illustrating a method of connecting conductive members (FIG. 14(A): resistance welding, FIG. 14(B): ultrasonic welding, FIG. 14(C): laser welding). FIG. 15 is a schematic diagram for explaining punching processing. FIG. 16 is a schematic plan view for explaining the "unsealing mechanism based on cell internal pressure action" and the "unsealing mechanism based on interference action." FIG. 17 is a schematic perspective view showing the appearance of a secondary battery according to an embodiment of the present invention. FIG. 18 is a schematic perspective view showing the appearance of a secondary battery as a modified embodiment of the present invention. FIG. 19 is a schematic diagram showing a second insulating member extending more outwardly as a modified embodiment of the present invention.

Below, a secondary battery according to one embodiment of the present invention will be described in more detail. Although explanations will be given with reference to drawings as necessary, various elements in the drawings are merely shown schematically and illustratively for understanding the present invention, and the appearance and/or dimensional ratio etc. may differ from the actual thing. It can be different.

A "cross-sectional view" described directly or indirectly in this specification is based on a hypothetical cross section of the secondary battery cut along the stacking direction of the electrode assembly or electrode constituent layers that constitute the secondary battery. ing. The direction of "thickness" described directly or indirectly in this specification is based on the lamination direction of the electrode materials constituting the secondary battery, the direction along the winding axis of the wound laminated structure, and the like. For example, in the case of a "thick plate-shaped secondary battery" such as a button type or coin type, the direction of "thickness" may correspond to the plate thickness direction of such a secondary battery. As used herein, "plan view" or "plan view shape" is based on a sketch when the object is viewed from above or below along the thickness direction or the normal/perpendicular direction to the main surface of the battery. ing.

The "vertical direction" and "horizontal direction" used directly or indirectly in this specification correspond to the vertical direction and the horizontal direction in the drawings, respectively. Unless otherwise specified, the same reference numerals or symbols indicate the same members or parts or the same meanings. In a preferred embodiment, the vertically downward direction (that is, the direction in which gravity acts) corresponds to the "downward direction," and the opposite direction corresponds to the "upward direction."

The various numerical ranges mentioned herein are intended to include the lower and upper numerical limits themselves, unless expressly stated otherwise. It should be noted that the terms "approximately" and "degree" mean that they may include variations or differences of several percentages, for example ±10%.

[Basic configuration of secondary battery]
The term "secondary battery" used herein refers to a battery that can be repeatedly charged and discharged. Therefore, the secondary battery according to the present invention is not excessively limited by its name, and may also include, for example, an electricity storage device.

The secondary battery according to the present invention includes an electrode assembly in which electrode constituent layers including a positive electrode, a negative electrode, and a separator are laminated. An electrode assembly 10 is illustrated in FIGS. 1(A) and 1(B). As shown in the figure, a positive electrode 1 and a negative electrode 2 are stacked with a separator 3 in between to form an electrode constituent layer 5, and an electrode assembly 10 is constructed by stacking at least one such electrode constituent layer 5. ing. In FIG. 1A, the electrode constituent layer 5 has a planar layered structure in which it is not wound but is stacked in a planar manner. On the other hand, in FIG. 1(B), the electrode constituent layer 5 has a wound laminated structure wound in a spiral shape. That is, in FIG. 1(B), the electrode constituent layer 5 including the positive electrode 1, the negative electrode 2, and the separator 3 disposed between the positive electrode 1 and the negative electrode 2 has a wound structure in which it is wound in a roll shape. . In a secondary battery, such an electrode assembly is enclosed in an outer case together with an electrolyte (for example, a non-aqueous electrolyte). Note that the structure of the electrode assembly is not necessarily limited to a flat layered structure or a wound structure. For example, the electrode assembly may have a so-called stack-and-fold structure in which a positive electrode, a separator, and a negative electrode are stacked on a long film and then folded.

The positive electrode is composed of at least a positive electrode material layer and a positive electrode current collector. In the positive electrode, a positive electrode material layer is provided on at least one side of the positive electrode current collector. The positive electrode material layer contains a positive electrode active material as an electrode active material. For example, the plurality of positive electrodes in the electrode assembly may each have a positive electrode material layer provided on both sides of a positive electrode current collector, or may have a positive electrode material layer provided only on one side of the positive electrode current collector. It may be something that exists.

The negative electrode is composed of at least a negative electrode material layer and a negative electrode current collector. In the negative electrode, a negative electrode material layer is provided on at least one side of the negative electrode current collector. The negative electrode material layer contains a negative electrode active material as an electrode active material. For example, the plurality of negative electrodes in the electrode assembly may each have a negative electrode material layer provided on both sides of a negative electrode current collector, or may have a negative electrode material layer provided only on one side of the negative electrode current collector. It may be something that exists.

The electrode active materials contained in the positive and negative electrodes, that is, the positive and negative electrode active materials, are substances that are directly involved in the transfer of electrons in secondary batteries, and are the main materials of the positive and negative electrodes that are responsible for charging and discharging, that is, battery reactions. be. More specifically, ions are brought into the electrolyte due to "the positive electrode active material contained in the positive electrode material layer" and "the negative electrode active material contained in the negative electrode material layer", and these ions are brought into contact between the positive electrode and the negative electrode. The battery moves and exchanges electrons to perform charging and discharging. The positive electrode material layer and the negative electrode material layer may be layers capable of intercalating and deintercalating lithium ions. That is, the secondary battery according to the present invention may be a non-aqueous electrolyte secondary battery in which lithium ions move between the positive electrode and the negative electrode via the non-aqueous electrolyte to charge and discharge the battery. When lithium ions are involved in charging and discharging, the secondary battery according to the present invention corresponds to a so-called "lithium ion battery" and has layers capable of inserting and extracting lithium ions as a positive electrode and a negative electrode.

The positive electrode active material of the positive electrode material layer is composed of, for example, granules, and a binder may be included in the positive electrode material layer for more sufficient contact between the particles and shape retention. Furthermore, a conductive additive may be included in the positive electrode material layer in order to facilitate the transmission of electrons that promote battery reactions. Similarly, when the negative electrode active material of the negative electrode material layer is composed of, for example, granules, a binder may be included for more sufficient contact between the particles and shape retention, and for the transfer of electrons that promote battery reactions. A conductive additive may be included in the negative electrode material layer to facilitate this. As described above, since a plurality of components are contained, the positive electrode material layer and the negative electrode material layer can also be referred to as a "positive electrode composite material layer" and a "negative electrode composite material layer," respectively.

The positive electrode active material may be a material that contributes to intercalation and desorption of lithium ions. From this point of view, the positive electrode active material may be, for example, a lithium-containing composite oxide. More specifically, the positive electrode active material may be a lithium transition metal composite oxide containing lithium and at least one transition metal selected from the group consisting of cobalt, nickel, manganese, and iron. That is, in the positive electrode material layer of the secondary battery according to the present invention, such a lithium transition metal composite oxide is preferably contained as a positive electrode active material. For example, the positive electrode active material may be lithium cobalt oxide, lithium nickel oxide, lithium manganate, lithium iron phosphate, or a material in which some of the transition metals thereof are replaced with another metal. Although such positive electrode active materials may be contained as a single species, they may be contained in a combination of two or more types.

The binder that can be contained in the positive electrode material layer is not particularly limited, but includes polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, and polytetrafluoroethylene. At least one selected from the group consisting of: The conductive additive that can be included in the positive electrode material layer is not particularly limited, but includes carbon black such as thermal black, furnace black, channel black, Ketjen black, and acetylene black, graphite, carbon nanotubes, and vapor phase growth. Examples include at least one selected from carbon fibers such as carbon fibers, metal powders such as copper, nickel, aluminum and silver, and polyphenylene derivatives.

The thickness of the positive electrode material layer is not particularly limited, but may be 1 μm or more and 300 μm or less, for example, 5 μm or more and 200 μm or less. The thickness dimension of the positive electrode material layer is the thickness inside the secondary battery, and the average value of the measured values at arbitrary 10 points may be adopted.

The negative electrode active material may be a material that contributes to intercalation and desorption of lithium ions. From this point of view, the negative electrode active material may be, for example, various carbon materials, oxides, and/or lithium alloys.

Various carbon materials for the negative electrode active material include graphite (natural graphite and/or artificial graphite), hard carbon, soft carbon, and/or diamond-like carbon. Examples of the oxide of the negative electrode active material include at least one selected from the group consisting of silicon oxide, tin oxide, indium oxide, zinc oxide, lithium oxide, and the like. The lithium alloy of the negative electrode active material may be any metal that can be alloyed with lithium, such as Al, Si, Pb, Sn, In, Bi, Ag, Ba, Ca, Hg, Pd, Pt, Te, Zn, It may be a binary, ternary or higher alloy of metal such as La and lithium.

The binder contained in the negative electrode material layer is not particularly limited, but at least one selected from the group consisting of styrene-butadiene rubber, polyacrylic acid, polyvinylidene fluoride, polyimide resin, and polyamideimide resin. can be mentioned. The conductive additives that can be included in the negative electrode material layer are not particularly limited, but include carbon blacks such as thermal black, furnace black, channel black, Ketjen black and acetylene black, graphite, carbon nanotubes, and vapor phase growth. Examples include at least one selected from carbon fibers such as carbon fibers, metal powders such as copper, nickel, aluminum and silver, and polyphenylene derivatives. Note that the negative electrode material layer may contain a component resulting from a thickener component (for example, carboxymethyl cellulose) used during battery manufacture.

Although the thickness dimension of the negative electrode material layer is not particularly limited, it may be 1 μm or more and 300 μm or less, for example, 5 μm or more and 200 μm or less. The thickness dimension of the negative electrode material layer is the thickness inside the secondary battery, and the average value of the measured values at arbitrary 10 points may be adopted.

A positive electrode current collector and a negative electrode current collector used in a positive electrode and a negative electrode are members that contribute to collecting and supplying electrons generated in an electrode active material due to a battery reaction. Such an electrode current collector may be a sheet-like metal member. Further, the electrode current collector may have a porous or perforated form. For example, the current collector may be metal foil, punched metal, mesh, expanded metal, or the like. The positive electrode current collector used in the positive electrode is preferably made of a metal foil containing at least one selected from the group consisting of aluminum, stainless steel, nickel, etc., and may be, for example, an aluminum foil. On the other hand, the negative electrode current collector used in the negative electrode is preferably made of a metal foil containing at least one selected from the group consisting of copper, stainless steel, nickel, etc., and may be a copper foil, for example.

Although the thickness dimensions of the positive electrode current collector and the negative electrode current collector are not particularly limited, they may be 1 μm or more and 100 μm or less, for example, 10 μm or more and 70 μm or less. The thickness dimension of the positive electrode current collector and the negative electrode current collector is the thickness inside the secondary battery, and the average value of the measured values at arbitrary 10 points may be adopted.

The separator used for the positive and negative electrodes is a member provided from the viewpoint of preventing short circuits due to contact between the positive and negative electrodes and retaining electrolyte. In other words, the separator can be said to be a member that allows ions to pass through while preventing electronic contact between the positive electrode and the negative electrode. For example, a separator is a porous or microporous insulating member that has a membrane shape due to its small thickness. By way of example only, a microporous membrane made of polyolefin may be used as the separator. In this regard, the microporous membrane used as the separator may contain, for example, only polyethylene (PE) or only polypropylene (PP) as the polyolefin. Furthermore, the separator may be a laminate composed of a "microporous membrane made of PE" and a "microporous membrane made of PP." The surface of the separator may be covered with an inorganic particle coating layer and/or an adhesive layer. The surface of the separator may have adhesive properties. In the present invention, the separator is not particularly limited by its name, and may be a solid electrolyte, a gel electrolyte, and/or insulating inorganic particles having similar functions.

The thickness of the separator is not particularly limited, but may be 1 μm or more and 100 μm or less, for example, 2 μm or more and 20 μm or less. The thickness dimension of the separator is the thickness inside the secondary battery (particularly the thickness between the positive electrode and the negative electrode), and the average value of the measured values at any 10 points may be adopted.

In the secondary battery of the present invention, an electrode assembly consisting of electrode constituent layers including a positive electrode, a negative electrode, and a separator may be enclosed in an exterior body together with an electrolyte. The electrolyte may be a "non-aqueous" electrolyte that includes an organic electrolyte and an organic solvent, or it may be an "aqueous" electrolyte that includes water. When the positive electrode and the negative electrode have a layer capable of intercalating and deintercalating lithium ions, the secondary battery preferably includes a "non-aqueous" electrolyte. That is, it is preferable that the electrolyte is a non-aqueous electrolyte. In the electrolyte there will be metal ions released from the electrodes (positive and/or negative), and therefore the electrolyte can assist in the movement of metal ions in battery reactions. Note that the electrolyte may have a liquid or gel form.

A non-aqueous electrolyte is an electrolyte containing a solvent and a solute. The solvent may be an organic solvent. A specific organic solvent for the non-aqueous electrolyte may contain at least carbonate. Such carbonates may be cyclic carbonates and/or linear carbonates. Although not particularly limited, examples of the cyclic carbonates include at least one selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC), and vinylene carbonate (VC). be able to. Examples of chain carbonates include at least one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC), and dipropyl carbonate (DPC). By way of example only, a combination of cyclic carbonates and chain carbonates may be used as the non-aqueous electrolyte, for example a mixture of ethylene carbonate and diethyl carbonate may be used. Moreover, as a specific solute of the non-aqueous electrolyte, for example, Li salt such as LiPF ₆ and/or LiBF ₄ may be used.

The exterior body of a secondary battery is a member that encloses an electrode assembly in which electrode constituent layers including a positive electrode, a negative electrode, and a separator are laminated. As will be described later, the exterior body may be a metal exterior body having a non-laminated structure.

[Characteristics of the secondary battery of the present invention]
The secondary battery of the present invention has features regarding the peripheral member provided in the exterior body that encloses the electrode assembly. In particular, it is characterized by a sealed structure and an external terminal structure related to the opening of the outer case of the secondary battery.

The secondary battery of the present invention has a battery configuration that has never been seen before in which both the battery is sealed and the external terminals are provided. An electrode terminal is provided in the opening of the exterior body that encloses the electrode assembly. The electrode terminal (positive electrode terminal or negative electrode terminal) of such a secondary battery is electrically connected to the electrode assembly through the opening of the exterior body. In the present invention, this electrode terminal is additionally provided with a sealing member for sealing the exterior body. That is, the sealing member constitutes a separate member different from the electrode terminal. In the present invention, the sealing member that closes the opening of the exterior body is a deformable member that can be deformed due to pressing force, and the main surface of the sealing member located inside the exterior body is smaller than the opening of the exterior body. There is.

2(A) and 2(B) show a cross-sectional view and a half-divided perspective view of a secondary battery 1000 according to an embodiment of the present invention, and FIGS. 3 and 4 show an exterior body 1000. The configuration of the secondary battery 1000 around the opening (hereinafter also referred to as "exterior body opening 150") is shown in a cross-sectional view. Furthermore, in order to facilitate understanding of the present invention, FIG. 5 separately shows elements related to the characteristics of the secondary battery of the present invention. As shown in FIGS. 3 to 5, the outer case 100 of the secondary battery has an outer case opening 150 as an opening for an external terminal. That is, in the secondary battery 1000 of the present invention, the electrode terminal 200 is disposed proximate to the exterior body opening 150. The electrode terminal 200 corresponds to an output terminal for connection with external equipment. The electrode terminal 200 may have a flat plate shape as a whole. In the secondary battery of the present invention, a sealing member 300 is additionally provided on such an electrode terminal 200. More specifically, the sealing member 300 combined with the electrode terminal 200 seals the exterior body opening 150 of the exterior body 100.

The sealing member 300 is a member separate from the electrode terminal 200 and is a member that exclusively contributes to sealing. Therefore, the exterior body opening 150 is sealed by the sealing member 300, and leakage of the electrolyte in the secondary battery is prevented, as well as leakage of gas generated within the exterior body is prevented. Furthermore, in the present invention, the sealing member that closes the opening of the exterior body is a deformable member whose shape can be changed by pressing force, and the size of the main surface of the sealing member located inside the exterior body corresponds to the opening of the exterior body (in plan view). opening size). Therefore, if a pressing force is applied to the sealing member due to an abnormal increase in the pressure inside the outer casing (i.e., "cell internal pressure"), the sealing member may deform and release internal gas, causing unintended battery damage. This can prevent more serious accidents such as explosions. Thus, a safer battery is provided by the sealing member being a separate deformable member different from the electrode terminals.

FIG. 4 shows the relationship between the exterior body opening 150 of the exterior body 100 and the sealing member 300 for better understanding. The sealing member 300 extends in the axial direction so as to straddle the exterior body opening 150. As shown in FIG. 4, in the sealing member 300, at least a main surface 335B (hereinafter also referred to as an "inner main surface") located inside the battery of the exterior body 100 is smaller than the exterior body opening 150. That is, when the opening dimension of the exterior body opening 150 is L _O and the width dimension of the inner main surface 335B of the sealing member is L _W , L _W < L _O. It can also be said that the area of the inner main surface 335B of the sealing member is smaller than the opening area of the exterior body opening 150. In a broad sense, "inside the exterior" refers to the internal area of the exterior, and in a narrow sense, it refers to the inside of the battery or the inside of the battery (in particular, the inside of the battery) from the exterior body part that has the exterior opening. refers to the inside or inside side in the axial direction of the secondary battery, which corresponds to the normal direction or perpendicular direction to the main surface. Simply put, the side of the sealing member that closes the opening of the exterior body that is closer to the electrode assembly corresponds to the "inside".

The sealing member 300 is a separate member different from the electrode terminal, and as shown in FIG. 6, it is preferable that the sealing member 300 includes an axially long body portion 350 whose height is larger than its width. In other words, it is preferable that the body of the sealing member 300 has an elongated shape. The "height dimension" here refers to the dimension of the sealing member (particularly its body) in the axial direction of the secondary battery (for example, the normal or perpendicular direction to the main surface of the battery), and the "width dimension" , refers to the dimension of the sealing member (especially its body) in the direction perpendicular to its height, that is, the dimension of the sealing member (especially its body) in the direction perpendicular to the axial direction of the secondary battery (e.g., the normal direction or perpendicular direction to the main surface of the battery). ing. Although such a sealing member suitably closes the opening of the exterior body, it is easily deformed in the axial direction of the sealing member when the cell internal pressure rises abnormally, contributing to a more suitable safety mechanism.

The sealing member 300 corresponds to a separate member different from the electrode terminal 200, and the electrode terminal 200 corresponds to an output terminal for connection with an external device. In other words, the sealing member 300 and the electrode terminals 200 are provided in the exterior body 100 to provide different functions, and while the sealing member 300 is disposed in the exterior body opening 150 as a member exclusively for sealing the battery, the electrode terminals 200 A terminal 200 is arranged in the exterior body opening 150 as an external output terminal. As for the configuration of a secondary battery that involves an opening in the exterior body, it is conceivable that an electrode terminal is provided in the opening in the exterior body as an output terminal, and the output terminal is substantially directly used to close the opening in the exterior body. However, the present invention does not have such a configuration, but has a new battery configuration in terms of battery sealing and terminal installation.

In the secondary battery of the present invention, the sealing member 300 is a member whose shape can be changed. As described above, the sealing member 300 is a deformable member that can be deformed by pressing force. The term "deformable by a pressing force" as used herein means that the sealing member is preferably able to change its shape without being damaged when a predetermined pressing force is applied. Such a pressing force may be caused, for example, by the cell internal pressure when the pressure inside the exterior body is abnormally increased.

In the secondary battery of the present invention, the body of the sealing member has an axial length that is larger in height than in width, as described above. That is, the body size of the sealing member in the axial direction is larger than the body size in the direction perpendicular to the axial direction. It can be said that the aspect ratio of the body size of the sealing member is greater than 1. In a cross-sectional view of the solid body of the sealing member 300 shown in FIG. 6, the aspect ratio (H/W), which is the ratio of the height (H) to the width (W), is larger than 1. It has become. The upper limit of the aspect ratio is not particularly limited, but may be, for example, about 4, 3, or 2. That is, the aspect ratio of the body of the sealing member is preferably about 1 to 4 or less, for example, about 1 to 3 or less, or, for example, about 1 to 2 or less. As can be seen from the illustrated embodiment, when the sealing member and its body have a circular shape in plan view, the "width dimension (W)" corresponds to the diameter dimension of the axially long member, and the "height dimension (H)" ” corresponds to the axial dimension of the long shaft member.

The axially long body 350 of the sealing member 300 may have a pillar shape as shown in FIG. 6 . For example, the solid body of the sealing member may have a rectangular cross-sectional shape. A typical example may be an aspect in which the width dimension of the axially long trunk portion 350 is substantially constant in the height direction, but the present invention is not necessarily limited thereto. That is, the width dimension of the pillar-shaped axially long body portion 350 may be non-uniform in the axial direction. The sealing member with the pillar-shaped axially long body preferably also serves as a safety mechanism when the internal pressure of the cell increases.

In a preferred embodiment, the sealing member has a flange-like portion, and the above-mentioned “principal surface of the sealing member” is provided on the flange-like portion. In other words, the "main surface of the sealing member" located inside the exterior body may correspond to the main surface of the brim-shaped portion of the sealing member. In the embodiment shown in FIG. 4, the sealing member 300 has a pair of flanges 335 and 365 at one end and the other end of the axially long body 350, which are located relatively inside the battery. The main surface 335B of the collar 335 (ie, the main surface of the collar distal to the axially elongated body so as to form the bottom surface of the sealing member) can be considered as the main surface of the sealing member. In such an aspect, the flange-like part of the sealing member located inside the exterior body (hereinafter also referred to as "inner flange-like part") may be smaller than the exterior body opening. In other words, when the sealing member has an inner flange and an outer flange, at least the width dimension or area of the inner flange (the area of the main surface of the flange or the area along the direction perpendicular to the axial direction of the sealing member) The cross-sectional area of the flange-shaped portion) is smaller than the width or area of the opening of the exterior body (the area of the opening in a plan view in the hollow region of the exterior body provided by the opening).

As mentioned above, the sealing member preferably includes an axially elongated body and a collar. More specifically, the sealing member includes an axially elongated body having one end (e.g., a bottom side or an end on the bottom side) and another end (e.g., a top side or an end on the top side) opposite each other. Often, a flange-like portion may be provided at each of the "one end" and the "other end". In this case, it is preferable that the flange-shaped portion provided on one end side has a non-uniform width dimension. In particular, in the sealing member, it is preferable that the width dimension of the inner brim portion is non-uniform.

As shown in FIG. 3, the end of the axially long trunk 350 located relatively inside the battery corresponds to "one end" 330, and the axially long trunk 350 located relatively outside the battery. The end of 350 may correspond to the "other end" 360. In the present invention, it is preferable that the width dimension of the brim portion 335 integrally provided at one end 330 of the axially long body portion 350 is non-uniform. That is, as illustrated, the axially long body 350 of the sealing member 300 is connected to an end 360' (hereinafter also referred to as an "outer end") that is relatively outer in the secondary battery 1000 and to the secondary battery 1000. It is preferable that the inner end 330' (hereinafter also referred to as an "inner end") be relatively inner than the inner end 330', and that the width dimension of the flange-shaped part 335 provided at the inner end 330' is non-uniform. . For example, the width dimension of the inner end side flange-like portion (namely, the inner flange-like portion) may be non-uniform in a stepwise or gradual manner. In the embodiments shown in FIGS. 3 and 6, the flange portion 335 provided at “one end” 330 corresponding to the inner end 330′ of the axially long body portion 350 has a width dimension that extends from the bottom surface of the sealing member to the top. It gradually decreases in the direction toward the surface. A sealing member having such a configuration not only contributes suitably to sealing the battery, but also preferably serves as a safety mechanism when the internal pressure of the cell increases.

From another perspective, the side surface of the inner brim portion of the sealing member may be a tapered surface. As shown in FIG. 6, this includes a flange 335 integrally provided at one end 330 of the axially long body 350 and a flange 335 integrally provided at the other end 360 of the axially long body 350. This means that the collar 335 at one end 330 located relatively inside the battery may have a tapered surface 335A. In a cross-sectional view taken along the axial direction of the secondary battery (for example, the normal or perpendicular direction to the main surface of the battery), the flange-shaped portion 335 located at one end 330 of the axially long body portion 350 has a tapered outline. It can be said that the contour 335A' may be included. As shown in FIG. 6, the width dimension of the inner collar portion 335 provided at one end 330 of the axially long body portion 350 gradually decreases in the direction from the one end 330 to the other end 360. It's okay to stay. In other words, in the secondary battery, the width of the inner brim portion 335 may be gradually reduced in the direction from the bottom surface to the top surface of the sealing member. As can be seen from the illustrated embodiment, the circumferential surface of the body of the inner collar portion 335 of the sealing member may form a tapered surface 335A. In the sealing member 300, the inner brim portion 335 may have an inclined surface or an inclined surface as the tapered surface 335A (see FIG. 3). As another example, as shown in FIGS. 3 and 6, the gradual change in the width dimension of the inner collar portion 335 due to the tapered surface may be substantially constant. The sealing member having a tapered surface at the inner flange-like portion not only contributes suitably to sealing the battery, but also preferably contributes to a safety mechanism when the internal pressure of the cell increases, which will be described later.

As an example of the unique shape of the sealing member described above, the cross-sectional view of the sealing member (i.e., the cross-sectional view cut along the axial direction of the secondary battery) preferably has a shape like an H-shape turned sideways. There is. That is, when the cross-sectional view shown in FIG. 2 or 6 is rotated by 90 degrees, the outline shape of the sealing member 300 may have an approximately H-shape as a whole. In other words, approximately the center of the axis of the sealing member has a relatively recessed shape in a direction perpendicular to the axial direction, preferably a large recessed shape (for example, the width of the sealing member is reduced to less than half). It has a concave shape. As can be seen from the sealing member having such a shape, the secondary battery of the present invention may have a hollow region around the axially long body portion of the sealing member. That is, a cavity may be provided as a battery area around the body of the sealing member. If such a hollow region is provided, the deformation of the sealing member at the time of an abnormal increase in the cell internal pressure can be made more suitable. More specifically, such deformation of the sealing member may correspond to buckling deformation, and the "hollow region" can appropriately secure a space for such deformation that increases the width dimension. Further, the hollow region can suitably serve as a flow path space through which internal gas flows when the sealed state is released by the safety mechanism.

In the sealing member, since the axially elongated body has an elongated shape in the axial direction or the longitudinal direction, the axially elongated body may have a height dimension larger than the thickness of the collar member. That is, as shown in FIG. 6, the thickness dimension of the flange 335 integrally provided at one end 330 of the axially long trunk 350 (i.e., the flange dimension in the axial direction) and/or the axially long trunk 350 The axially long body part 350 has a height dimension in the axial direction that is larger than the thickness dimension of the flanged part 365 (i.e., the flanged dimension in the axial direction) that is integrally provided at the other end 360 of the body part 350. good. Such a unique shape makes it easier to seal the secondary battery properly, and also makes it easier to perform the safety function described later.

The sealing member 300 used in the present invention is, for example, “solid” and therefore does not have a hollow portion inside. That is, the inner region of the cross-sectional profile of the sealing member may be entirely occupied by the material of the sealing member. The material of the sealing member may be metal. That is, the sealing member may be a metal member. There is no particular restriction on the type of metal material, as long as it is made of metal and contributes to sealing the battery. Note that when more emphasis is placed on the shape deformation of the sealing member, the sealing member is preferably made of an easily deformable metal material, and may include, for example, an aluminum alloy and/or mild steel. Note that the sealing member is preferably provided with a flanged portion at one end and the other end of the axially long body, but the axially long body and the flanged portion may be made of the same material. . Further, in the sealing member, the axially long body portion and the brim portion may be integrated with each other. That is, the sealing member including the axially long body and the flange may form a single part as an integral body.

In the secondary battery of the present invention, the electrode terminal is electrically connected to the electrode assembly. A conductive member extending from the electrode assembly may be directly connected to the electrode terminal, or a conductive member may be indirectly connected to the electrode terminal. In a preferred embodiment, the electrode terminal and the electrode assembly are electrically connected to each other via a sealing member. For example, as shown in FIG. 7, a conductive member 400 (eg, a so-called "tab") extending from the electrode assembly is electrically connected to the electrode terminal 200 via a sealing member 300. More specifically, a conductive member 400 extending from the electrode assembly is connected to the sealing member 300, and the sealing member 300 may also be connected to the electrode terminal 200.

As shown in FIG. 7, the inner main surface 335B corresponding to the bottom surface of the sealing member 300 and the upper surface 410 of the conductive member 400 are joined to each other, so that the sealing member 300 and the conductive member 400 are electrically connected to each other. It's good that it has been done. For example, the sealing member 300 and the conductive member 400 may be joined by welding. In the sealing member 300, the inner main surface 335B preferably has a flat surface. In the sealing member 300 shown in FIG. 6, the flange-like portion 335 provided at one end 330 of the axially long body portion 350 is on its main surface (in short, the inner main surface 335B forming the bottom surface of the sealing member 300). It preferably has a flat surface. Therefore, the sealing member 300 and the conductive member 400 can be suitably connected to each other via the flat surface of the sealing member 300. For example, the flat inner main surface 335B of the sealing member 300 and the upper surface 410 of the conductive member 400 may be welded together.

As shown in FIG. 7, the electrode terminal 200 and the sealing member 300 may be connected to each other via a terminal opening edge 225 that forms a terminal opening 220 at the electrode terminal 200. Specifically, the electrode terminal 200 is provided with a terminal opening 220 that overlaps with the exterior body opening 150 and in which the sealing member 300 is disposed. The terminal opening edge 225 may be connected to the sealing member 300. For example, the terminal opening edge 225 may be connected to a flange-like portion 365 on the outer end side of the axially long body portion 350 at the sealing member 300 (see FIG. 7). In other words, the terminal opening edge 225 of the electrode terminal 200 may be connected to the outer collar portion 365 in the secondary battery. As shown in FIG. 7, the terminal opening edge 225 forming the terminal opening 220 extends toward the sealing member 300 so as to exceed the insulating member 500 extending between the electrode terminal 200 and the exterior body 100. It may extend to the side surface and/or bottom surface of the outer brim portion 365 (the "insulating member" will be described later). In particular, in FIG. 7, the terminal opening edge 225 and the outer side are arranged so that the terminal opening edge 225 is in complementary contact with the recess or stepped portion 366 (a step-shaped portion when viewed in cross section) on the side surface of the flange-shaped portion 365. The flanged portions 365 are connected to each other.

In a preferred embodiment, the electrode terminal has a terminal opening that overlaps with the opening of the exterior body, and a sealing member positioned at the terminal opening closes the opening of the exterior body. This means that the electrode terminal has a terminal opening positioned so as to overlap the opening of the exterior body of the exterior body, and the sealing member is provided so as to close the exterior body opening via the terminal opening. That is, the electrode terminal is arranged so that its terminal opening overlaps with the opening of the exterior body, and the sealing member arranged to fit in the terminal opening closes the opening of the exterior body. In the embodiments shown in FIGS. 2 to 5, the electrode terminals 200 are arranged in the exterior body 100 so that the terminal opening 220 and the exterior body opening 150 are concentric with each other or form concentric circles, thereby making it common. A sealing member 300 is placed over the opening. As can be seen in particular from the form shown in FIG. 3, the sealing member 300 positioned inside the terminal opening 220 is at the level of the exterior body opening edge 155 forming the exterior body opening 150 (particularly at the edge 155a of the exterior body opening edge 155). , and the sealing member 300 suitably closes the "hole" of the housing opening 150. In a preferred embodiment, an inner brim portion 335 provided on one end 330 (i.e., inner end 330') side of the elongated body portion 350 in the sealing member 300 connects the “hole” of the exterior body opening 150 more directly. It's blocking the target. In this way, the sealing member disposed in the terminal opening as a separate member from the electrode terminal provided as an external output terminal suitably contributes to sealing the battery.

In the secondary battery of the present invention, the electrode terminal is an output terminal for connection with external equipment. The electrode terminal 200 has, for example, a flat plate shape (see FIG. 5). In other words, the electrode terminal may be a flat member. The flat electrode terminal may be, for example, a metal disk. Since the electrode terminal has a flat plate shape, the thickness of the electrode terminal may be substantially constant. The material of the electrode terminal 200 is not particularly limited as long as it has electrical conductivity. The electrode terminal may be made of a metal material that is generally used as a terminal material for secondary batteries. For example, the electrode terminal may include at least one metal selected from the group consisting of SUS, aluminum, nickel, and copper. The shape of the electrode terminal in plan view is not particularly limited, and may be circular or polygonal including quadrangles. Note that the material of the electrode terminal may be relatively more rigid than the exterior body.

In the secondary battery of the present invention, an insulating member may be provided between the electrode terminal and the exterior body. Providing an insulating member enables a suitable battery design. In other words, by providing an insulating member between the electrode terminal and the exterior body, electrical disconnection can be appropriately achieved between them, and it is possible to make the electrode polarities different between the electrode terminal and the exterior body. It becomes possible. In the embodiment shown in FIG. 3, an insulating member 500 extending in the width direction of the battery is provided between the electrode terminal 200 and the exterior body 100. In such a case, the insulating member 500 may be provided so as to extend inward in the plane direction from the peripheral edge region 130 of the exterior body corresponding to the outer peripheral edge of the battery (see FIG. 3).

Further, in the secondary battery of the present invention, an insulating member is provided between the outer casing opening edge forming the outer casing opening and the sealing member. That is, the insulating member may be provided to be interposed between the sealing member (particularly the side surface thereof) disposed in the opening of the exterior body and the edge of the opening of the exterior body. Thereby, even though the main surface located inside the exterior body is a sealing member that is smaller than the exterior body opening, the sealing member can more suitably close the exterior body opening. In the embodiment shown in FIG. 3, an insulating member 500 is provided between the flange-like part (particularly the inner flange-like part 335) of the sealing member 300 disposed in the exterior body opening 150 and the exterior body opening edge 155. . As shown in the figure, an insulating member 500 may preferably be provided so as to be interposed at least between the side surface of the inner brim portion 335 of the sealing member 300 and the side surface of the exterior opening edge 155.

In a preferred embodiment, the insulating member may include a first insulating member and a second insulating member. For example, the secondary battery of the present invention has a first insulating member provided between the electrode terminal and the exterior body, and a second insulating member provided between the exterior body opening edge forming the exterior body opening and the sealing member. An insulating member may be provided. 3 and 7, the first insulating member 520 is positioned relatively outward in the plane direction (outward in the cell width direction) and extends between the electrode terminal 200 and the exterior body 100, while the first insulating member 520 is A configuration is shown in which the second insulating member 540 is located relatively inside in the plane direction (inside in the battery width direction) and is provided between the exterior body opening edge 155 and the sealing member 300. As illustrated, the first insulating member 520 and the second insulating member 540 as insulating members may be adjacent to each other, preferably in contact with each other (for example, inside the first insulating member 520 in cross-sectional view). (The side surface and the outer side surface of the second insulating member 540 may be at least partially in contact with each other.)

Preferably, the exterior body opening edge 155 and the sealing member 300 are pressed against each other via the second insulating member 540 (see FIG. 7). That is, in the secondary battery of the present invention, the sealing member 300 including the axially long body portion 350 is provided so as to tightly fit into the outer case opening 150, so that the sealing member 300 is provided with respect to the insulating member 500 on the outer case opening edge 155. A suitable pressing force is applied, and as a result, more suitable sealing is achieved. The term "press contact" used herein refers to a state in which the parts are in close contact with each other under pressure and/or compressive force, rather than simply in contact with each other. For example, when the exterior body opening edge 155 is under pressure from the sealing member 300 via the second insulating member 540 or with a drag force against the sealing member 300, Closely adjacent to sealing member 300 . Similarly, the sealing member 300 also receives pressure from the opening edge 155 of the exterior body through the second insulating member 540, or the second insulation member 540 and closely adjacent the outer body opening edge 155 . In this embodiment, the opening edge 155 of the exterior body and the sealing member 300 are in pressure contact with each other via the insulating member 500. It can also be said that the opening edge 155 of the exterior body is also pressed into contact with the insulating member 500. In particular, the sealing member 300 (preferably the inner flange-like portion 335 thereof) is in pressure contact with the second insulating member 540, and the exterior body opening edge 155 is also in pressure contact with the second insulating member 540. When the insulating member 500 is made of a resin member, which will be described later, the insulating member 500 is in a compressed state due to such pressure contact. In particular, when the sealing member is pressed and fitted into the insulating member (preferably the second insulating member 540) on the opening edge of the exterior body, the sealing member is attached to the inner flange-shaped portion of the shaft member 350. The insulating member 500 (preferably the second insulating member 540) in contact with the inner brim portion 335 is more preferably compressed due to the “non-constant width” and/or “tapered surface” of the side wall surface of the inner brim portion 335. (Preferably, it is compressed from more directions), and the sealing can be made more stable.

In this specification, the term "insulating member" refers to a member that is interposed between at least the exterior body and the electrode terminal and/or the sealing member and contributes to "insulation" between them. There are no particular restrictions on the type of material of the insulating member as long as it exhibits "insulating properties." The insulating member is formed from a material commonly used as an insulating material for secondary batteries (i.e., a material commonly used as an insulating material in secondary batteries, preferably a material commonly used for sealing as an insulating material for secondary batteries). may have been done.

In a preferred embodiment, the insulating member 500 is made of a resin material. That is, the insulating member 500 may be a resin member. For example, at least one of the first insulating member 520 and the second insulating member 540 may be a resin member. Preferably, both the first insulating member 520 and the second insulating member 540 are each made of a resin member. The resin material used for the insulating member 500 may belong to types such as thermoplastic resins, thermosetting resins, and/or engineered plastics. To give a more specific example of the resin material of the insulating member, PFA resin, which is a fluororesin, is preferable in terms of reliability and/or moldability, but is not limited thereto. As a thermoplastic resin, polyolefin such as PE resin and/or PP resin may be included in the insulating member, and as an engineering plastic, PBT resin, PPS resin and/or LCP resin may be included in the insulating member. The insulating member may contain a phenol resin and/or an epoxy resin as the curable resin. Since the insulating member also contributes to "sealing" between the opening of the exterior body and the sealing member, the insulating member is also referred to as a "sealing insulating member," "sealing member," or "sealing resin member." It can also be called. Similarly, the first insulating member can be referred to as an "outer sealing insulating member", "outer sealing member", or "outer sealing resin member" because it can be positioned relatively outward in the width direction, Since the second insulating member can be positioned relatively inward in the width direction, it can be referred to as an "inner sealing insulating member," "inner sealing member," or "inner sealing resin member."

The insulating member interposed between the opening edge of the exterior body and the sealing member may have a more suitable form in relation to battery sealing. Specifically, as shown in FIG. 8, the second insulating member 540 may extend over the edge 155a of the opening edge 155 of the exterior body. Preferably, the second insulating member 540 provided so as to be sandwiched between the opening edge 155 of the exterior body and the sealing member 300 (preferably the brim portion 335 thereof) extends beyond the edge 155a of the opening edge 155 of the exterior body. Or it may extend to straddle it. In the embodiment shown in FIG. 8, the second insulating member 540 has a protrusion 545 (particularly a protrusion 545 that protrudes radially outward) so as to straddle the edge 155a of the opening edge 155 of the exterior body. In the second insulating member 540 that extends over or straddles the edge 155a of the opening edge 155 of the exterior body, the sealing area increases, and more suitable sealing can be achieved.

For example, the exterior body opening edge may be a burred edge. That is, as shown in FIG. 8, the exterior body opening edge 155 that is erected or thickened so as to surround the exterior body opening 150 can be provided by burring. The second insulating member 540 that extends over or straddles the edge 155a of the opening edge 155 of the exterior body electrically insulates such a burring end, and can more preferably prevent electrical contact between the conductive member 400 and the exterior body 100. . Moreover, the second insulating member 540 and the exterior body 100 are more suitably integrated by the second insulating member 540 exceeding or straddling the edge 155a of the opening edge 155 of the exterior body.

The secondary battery of the present invention is preferably provided as a safer battery. For example, if an abnormal situation occurs in which the internal pressure of the exterior body increases, the secondary battery preferably has a mechanism for releasing the seal in order to prevent a more serious accident such as an unintentional battery explosion. In other words, this is to prevent the battery from exploding due to an increase in the pressure inside the outer casing (also referred to as "cell internal pressure" in this specification) due to gas generated by abnormal heat generation inside the battery due to overcharging or internal short circuit, etc. Furthermore, it is preferable that the secondary battery is provided with a mechanism that releases gas when the cell internal pressure rises excessively. In this regard, the secondary battery of the present invention is preferably configured so that the sealing member can release its sealed state when the cell internal pressure increases excessively.

In the present invention, the sealing member is a deformable member that can change shape due to the increased cell internal pressure of the secondary battery. That is, when the internal pressure of the cell increases excessively, the sealing member can deform in response to the pressure to release the sealed state of the battery. For example, as shown in FIG. 9, the external force received from the increased cell internal pressure P of the secondary battery changes the shape of the sealing member 300 fitted into the exterior opening 150, thereby improving the airtightness of the exterior opening 150. is broken (FIG. 9 shows an example of the flow F of the internal gas that breaks the airtightness and escapes to the outside). In this regard, in the secondary battery 1000 of the present invention, the main surface 335B of the sealing member 300 located inside the exterior body 100 is smaller than the exterior body opening 150 (see FIG. 4), so that a pressing force is applied to the sealing member. The shape deformation of the sealing member is not inhibited by the exterior body when the sealing member is applied. Further, the sealing member 300 is easily deformed in its height direction, especially due to the axially long body portion 350. Specifically, the sealing member 300 is easily deformed such that the height dimension is reduced due to the increased cell internal pressure, and therefore the sealing member 300 is provided as a deformable member. Since the airtightness of the exterior body opening 150 is preferably broken as the sealing member 300 deforms, it can be said that the sealing member can preferably release its sealed state when the cell internal pressure increases excessively. As described above, in the secondary battery of the present invention, preferably due to the unique shape of the sealing member, the sealing member that contributes to sealing the battery is likely to deform when the cell internal pressure abnormally increases, and the desired Safety features are advantageously provided.

In a preferred embodiment, the opening edge 155 of the exterior body and the sealing member 300 are pressed against each other via the insulating member 500, so that when the cell internal pressure P increases excessively, the pressed state is released. The sealing member 300 is deformed (see FIG. 10). For example, the sealing member 300 can be deformed so that the sealing member buckles under the internal pressure P, thereby preventing a more serious accident such as an unintended explosion of the secondary battery. Preferably, when the sealing member 300 deforms to release the press-contact state, the connection with the conductive member 400 is cut (see FIG. 10), and the power supply is suitably cut off, thereby preventing subsequent overcharging. Easy to prevent. In other words, it is possible to prevent undesired electrical events when the internal pressure is released.

In one preferred embodiment, the sealing member is based on a deformation of the axial length body. That is, the axially elongated body portion 350 may be deformed by the external force received from the increased cell internal pressure of the secondary battery, thereby allowing the sealing member 300 to change its shape. In such a case, the axially elongated body 350 of the sealing member 300 may deform to reduce its axial dimension due to the increased cell internal pressure. FIG. 11 illustrates a modification in which the height of the sealing member 300 is reduced by deforming the axially long body 350. For example, when the exterior opening edge 155 and the sealing member 300 (preferably the brim portion 335 thereof) are pressed against each other via the insulating member 500 (preferably the second insulating member 540), the cell internal pressure may be excessively high. When raised, the sealing member 300 may be deformed based on the deformation of the axially long body portion 350 so that the press-contact state is released (see FIG. 10).

Preferably, when the sealing member is deformed to release the press-contact state, the insulating member is broken or cut. For example, an insulating member provided between the opening edge of the exterior body and the sealing member may be subjected to rupture or cutting. In particular, the sealing member may deform to cause rupture in the second insulating member due to increased cell internal pressure of the secondary battery. In a preferred embodiment, the electrode terminal has a terminal opening that overlaps with the opening of the exterior body, and the sealing member that is positioned in the terminal opening and blocks the opening of the exterior body, due to the increased cell internal pressure of the secondary battery, The deformation occurs so as to cause breakage of the insulating member provided at the edge of the exterior body opening that forms the exterior body opening. By breaking and cutting the insulating member in this manner, the airtightness at the opening of the exterior body is more appropriately broken, and a safer battery can be provided.

More specifically, when the cell internal pressure increases excessively, the inner main surface 335B of the sealing member 300 located inside the exterior body (preferably the inner main surface 335B forming the bottom surface of the sealing member 300) P (see FIGS. 9 and 10). The sealing member 300 that has received the internal pressure P is subjected to a force that moves outward (towards the top in the drawing) due to its deformation stress. A force is also applied to the insulating member 500 to move it outward (towards the top in the drawing). Therefore, the insulating member 500 provided so as to straddle the exterior opening edge 155 (particularly the edge 155a thereof) receives a shearing force from the edge 155a, which ultimately causes the insulating member 500 to break. Action occurs. In such a safety mechanism, it is more preferable to have a "non-uniform width dimension" and/or a "tapered surface" of the inner flange provided on one end (especially on the inner end of a secondary battery). Contributes to rupture. Specifically, the inner brim portion 335 having a non-uniform width dimension and/or a tapered surface is configured to more effectively apply an outward force to the insulating member 500 when the cell internal pressure abnormally increases. act. In particular, the brim portion 335 of the sealing member has a side wall surface based on "non-uniform width dimension" and/or a "tapered surface," and the second insulating member 540 has an inner surface complementary to the side wall surface. Then, the brim portion 335 of the sealing member 300, which tends to move outward due to the deformation caused by the abnormal rise in cell internal pressure, applies outward stress to the second insulating member 540 via the complementary inner surface. You can communicate more effectively. Therefore, the second insulating member 540 receives the shearing force more effectively from the edge 155a of the opening edge 155 of the exterior body, and finally the second insulating member 540 is more easily broken (see FIGS. 9 and 9). (See Figure 10). In other words, the "non-uniform width dimension" and/or "tapered surface" of the brim of the sealing member contributes to more effectively breaking the airtightness of the opening of the exterior body, and is more effective when the cell internal pressure rises abnormally. Contributes to suitable internal gas release.

In a preferred embodiment, the outer casing opening edge forming the outer casing opening has a sharp edge. In other words, the tip of the wall portion that is erected or thickened so as to surround the exterior body opening 150 has a sharp shape. FIG. 12 shows an opening edge 155 of the exterior body, the edge 155a of which is a sharp edge pointing downward. As can be seen from the illustrated form, the term "sharp edge" as used in the present invention, in a broad sense, includes a shape in which the leading edge of the opening edge of the exterior body is sharp, for example, in a cross-sectional view. This means that the edges of the housing opening (particularly their leading edges) have an angular rather than a rounded contour. Such a sharp edge of the opening edge of the exterior body suitably contributes to releasing internal gas when the internal pressure of the cell increases abnormally. In other words, when the opening edge of the exterior body has a sharp edge, the shearing force that the insulating member 500 receives from the edge 155a of the opening edge of the exterior body becomes more effective when the cell internal pressure rises abnormally, and the breakage of the insulating member 500 is prevented. It becomes even more likely to occur (see FIGS. 9 and 10). In other words, the insulating member is effectively broken and cut by the sharp edge of the opening edge of the exterior body, and the airtightness of the exterior body opening is more effectively broken, making it suitable for releasing internal gas when the internal cell pressure rises abnormally. Become something.

As described above, when the insulating member 500 is composed of the first insulating member 520 and the second insulating member 540, the second insulating member 540 is provided so as to straddle the exterior opening edge 155 (particularly the edge 155a thereof). It's okay to stay. Therefore, breakage of the insulating member when the cell internal pressure abnormally increases preferably occurs at the second insulating member 540. In other words, the second insulating member 540, which is provided between the exterior body opening edge 155 and the sealing member 300 and is provided so as to straddle the edge 155a of the exterior body opening edge 155, is removed from the outside when the cell internal pressure is abnormally increased. Due to the sealing member 300 trying to move toward the upper side in the drawing, it receives a shearing force from the edge 155a of the opening edge 155 of the exterior body, and eventually the second insulating member 540 breaks. . Such breakage of the insulating member is preferably based on the shearing force that the insulating member receives from the edge 155a of the opening edge 155 of the exterior body as the sealing member 300 moves when the cell internal pressure abnormally increases. Therefore, if more emphasis is placed on using such shearing force to efficiently rupture the insulating member, it is preferable that the edge 155a of the opening edge 155 of the exterior body has a sharp edge. Here, in the present invention, even if the edge 155a of the opening edge 155 of the exterior body is not sharp, the insulating member may break due to the shearing force. This can be said to be an element that contributes to promoting rupture. In other words, in the secondary battery of the present invention, the sharp edges of the opening edge of the outer case assist in breaking or cutting the insulating member (preferably the second insulating member), thereby preventing internal gas release when the cell internal pressure abnormally increases. can be done more reliably.

The sharp edge provided on the opening edge 155 of the exterior body preferably has a "cutting edge" shape, as can be seen from the shapes shown in FIGS. 8 and 12. In other words, the edge 155a of the opening edge 155 of the exterior body has a cutting edge shape to more easily cause the insulating member (for example, the second insulating member 540) to be cut in the event of an abnormal internal pressure in which the internal cell pressure increases excessively. Regarding the shape of this type of cutting blade, the cutting edge does not necessarily have to be at the same height, and even if the blade shape has some unevenness, as long as the tip of the edge is sharp, it can be used as an insulating member in case of abnormal internal pressure. Contributes to cutting and breaking. The internal gas release pressure can be adjusted depending on the degree of sharpness of the sharp edge of the opening edge of the exterior body. For example, in the cross-sectional profile of a sharp edge, the internal gas release pressure can be lowered by making the angle between the edges smaller (e.g., by making the acute angle smaller), whereas by making the angle larger (e.g., by making the acute angle smaller), the internal gas release pressure can be lowered. If the angle is made larger or obtuse angle), the internal gas release pressure can be increased.

The internal gas release pressure can also be adjusted by adjusting the thickness of the insulating member. In particular, the thickness of the second insulating member, more specifically, the thickness of the portion of the second insulating member 540 that straddles the edge 155a of the opening edge 155 of the exterior body (hereinafter referred to as "straddling of the second insulating member"). The internal gas release pressure can be adjusted by adjusting the size of the partial thickness (also referred to as "partial thickness"). If you want to lower the internal gas release pressure, you just need to make the thickness of the straddling part of the second insulating member smaller, and conversely, if you want to increase the internal gas release pressure, you can make the thickness of the straddling part of the second insulating member larger. Bye. In the present invention, the release of internal gas when the internal pressure is abnormal does not necessarily require that the insulating member (especially the second insulating member) be completely broken or cut, but rather that the insulating member (especially the second insulating member) may be cracked. If so, the internal gas can be discharged, and the internal pressure of the cell can be reduced in the event of an abnormality.

In the secondary battery of the present invention, the electrode terminal and the sealing member are provided to the exterior body. Here, the term "exterior body" as used herein refers to a member for housing or enveloping an electrode assembly in which electrode constituent layers including a positive electrode, a negative electrode, and a separator are laminated. For example, the sheath may be a metal sheath having a non-laminated configuration. This means that the exterior body is not a laminate member consisting of a metal sheet/fusion layer/protective layer. It can be said that the exterior body in the present invention may be different from the exterior body of a soft case type battery, which corresponds to a pouch made of a so-called laminate film. A metal sheath having a non-laminated construction preferably has a construction consisting of a single piece of metal. For example, such a metal exterior body may be a single member made of metal such as stainless steel (SUS) and/or aluminum. In a broad sense, the term "single metal member" here means that the exterior body does not have a so-called laminate structure, and in a narrow sense, the exterior body is a member that consists essentially only of metal. It means that. Therefore, as long as the member is made essentially only of metal, the surface of the metal sheath may be subjected to an appropriate surface treatment. For example, in a cut surface obtained by cutting such a metal exterior body in its thickness direction, a single metal layer can be observed except for areas where surface treatment has been performed. Note that "stainless steel" in this specification refers to, for example, stainless steel defined in "JIS G 0203 Steel Terminology", and may be chromium or an alloy steel containing chromium and nickel. In a preferred embodiment, the outer package may have the form of a can (in such a case, it is also referred to herein as an "outer can").

In the secondary battery of the present invention, the exterior body may be mainly composed of two parts. For example, the exterior body may be composed of two parts: a first metal exterior body and a second metal exterior body, which are metal members. In the case of an exterior body having a non-laminated structure, each of the first metal exterior body and the second metal exterior body may be a single metal member. In the present invention, the exterior body may have a relatively thin thickness. For example, each of the first metal exterior body and the second metal exterior body may have a thickness dimension of 50 μm or more and less than 200 μm, for example, 50 μm or more and 190 μm or less, 50 μm or more and 180 μm or less, or 50 μm or more and 170 μm or less. It may be.

In an exterior body made up of two parts, a first metal exterior body and a second metal exterior body, the above-mentioned “exterior body opening” may be provided in one of the first metal exterior body and the second metal exterior body. That is, either one of the first metal exterior body and the second metal exterior body may be provided with an opening, and the electrode terminal and the sealing member may be provided to one of the sub-exterior bodies having the opening. Note that the first metal sheath and the second metal sheath of the metal member may be combined with each other by laser welding to form a sheath, or may be combined with each other by caulking to form a sheath.

One of the first metal exterior body and the second metal exterior body may be a cup-shaped member, and the other of the first metal exterior body and the second metal exterior body may be a lid-shaped member. In such a case, for example, the metal exterior bodies may be joined together by welding or caulking the peripheral portion of the lid-like member from the outside, which may enable relatively simple encapsulation. A "cup-shaped member" has a side wall or side part corresponding to a body part and a main surface part (typically, for example, a bottom part) that is continuous with the side wall or side part, and has a hollow part formed inside. It means a member. In addition, the term "lid-like member" refers to a member that is assembled to cover the cup-like member (preferably, a member that is combined to cover the cup-like member (preferably, a member that is in contact with the side wall of the cup-like member to block the inner hollow part of the cup-like member from the outside). means a member installed in the The lid-like member is, for example, a single member (typically a flat member) extending in the planar direction (particularly in a direction perpendicular to the direction in which the side wall of the cup-like member extends in an upright manner). In particular, it may be a member provided so as to be in contact with the side wall of the cup-shaped member.

In such a case, the above-mentioned "exterior body opening" may be provided in the lid-like member. That is, the exterior body is composed of the cup-shaped member 100A and the lid-shaped member 100B, and the lid-shaped member 100B may have the exterior body opening 150 (see FIG. 5). When the lid-like member includes an exterior body opening, an electrode terminal and a sealing member are provided to the lid-like member. In such a case, a combination body in which an electrode terminal and a sealing member are provided on a lid-like member can be obtained once, and a secondary battery can be manufactured relatively easily.

[Method for manufacturing a secondary battery of the present invention]
The secondary battery of the present invention can be obtained by enclosing an electrode assembly in which electrode constituent layers including a positive electrode, a negative electrode, and a separator are laminated in an exterior body.

The electrode assembly may be manufactured by a conventional method, and a secondary battery can be obtained by placing the electrode assembly within the outer case. For example, when the exterior body is composed of the above-mentioned cup-shaped member and lid-shaped member, the secondary battery is installed through the step of placing the electrode assembly inside the cup-shaped member and closing the open end of the cup-shaped member with the lid-shaped member. Obtainable.

For example, when providing the electrode terminal and the sealing member to the lid-like member of the exterior body, the sealing member may be provided while combining the electrode terminal and the lid-like member so that the terminal opening and the exterior body opening overlap each other. It is preferable that an insulating member be interposed between the electrode terminal and the lid-like member. A sealing member can be included in the combination to close the housing opening through the terminal opening. The bottom portion of the sealing member has a main surface size smaller than the opening size of the exterior body opening. Preferably, the sealing member 300 has a main surface size smaller than the opening size of the exterior body opening (more preferably, a sealing (size of the bottom main surface of the member). When installing the sealing member, an insulating member may be interposed so that the opening edge of the exterior body and the sealing member are pressed against each other, thereby providing a suitable seal.

The sealing member itself can be obtained by conventional metal working methods. For example, the sealing member can be obtained through a rolling process. The sealing member may be a member that maintains its shape when installed in the opening of the exterior body, but it may also be used as a member that changes shape. For example, when installing the sealing member in the opening of the exterior body, an external force may be applied to the sealing member from the outside to deform the brim portion of the sealing member. For example, the flange 365 (ie, the outer flange 365) provided at the other end 360 of the elongated shaft member 350 may be deformed. FIG. 13 shows a form in which the undeformed outer brim portion 365 is deformed by an external force (particularly an external force acting toward the inside of the sealing member along the axial direction of the sealing member) when installing the sealing member. ing. By deforming the outer flanged portion in this manner, the flanged portion and the terminal opening edge can be easily joined tightly to each other. In other words, the sealing member and the electrode terminal can be suitably connected to each other through deformation of the flange-shaped portion (particularly the outer flange-shaped portion 365) (this will be described in detail below). As can be seen from the form shown in FIG. 13, the sealing member 300 may include an axially long body portion 350 whose height dimension is already larger than its width dimension before it is subjected to deformation.

When the sealing member is provided in the opening of the exterior body as the sealing member is deformed, the electrical connection between the sealing member and the electrode terminal can be made more suitably. More specifically, when installing the sealing member, the sealing member 300 may be suitably connected to the terminal opening edge 225 by applying an external force to the sealing member from the outside. In particular, the state in which the flanged portion 365 provided at the other end 360 of the elongated shaft member 350 (that is, the outer flanged portion 365) and the terminal opening edge 225 of the electrode terminal 200 are in contact with each other (more specifically, the outer flanged portion 365) By applying a pressing force to the collar (with the lower surface of the collar and the edge of the terminal opening edge 225 in contact with each other), the outer collar 335 is configured to at least partially cover the terminal opening edge 225. It can be joined to the terminal opening edge 225 while deforming it (see FIG. 7). In other words, the flanged portion subjected to the pressing action is more closely joined to the terminal opening edge, and a more suitable electrical connection between the sealing member and the electrode terminal can be achieved. Regarding such a connection, as shown in FIG. 7 and FIG. ).

When installing the sealing member in the opening of the exterior body, the sealing member may be pressed in a direction that compresses the sealing member in its axial direction (height direction). The "non-constant width dimension" and/or the "tapered surface" of the flange-shaped part 335 (namely, the inner flange-shaped part 335) provided in the inner flange-shaped part 335 can contribute to more suitable battery sealing. Specifically, the inner flanged portion 335 having a non-uniform width dimension and/or a tapered surface exerts a suitable force on the insulating member 500 on the exterior body opening edge 155 when the sealing member is pressed and installed. As a result, the sealing member 300 and the insulating member 500 (particularly the second insulating member 540) can be more preferably pressed against each other (see FIG. 7). In other words, the opening edge of the exterior body and the sealing member are more easily brought into pressure contact with each other through the insulating member, and more suitable sealing can be achieved. When the insulating member is constituted by the first insulating member and the second insulating member, the opening edge of the exterior body and the sealing member are more easily brought into pressure contact with each other through the second insulating member. Although not bound by any particular theory, it is possible that the sealing member (particularly the inner flange portion 335 thereof) has a flange slope such as a tapered surface, and the second insulating member has an inner surface that complementarily mates with the tapered surface. If so, it is thought that the stress received from the sealing member (particularly the inner brim portion 335 thereof) will work more preferably on the inner surface of the second insulating member toward the outside as the sealing member is press-installed. In other words, stress is likely to be generated in the second insulating member outward in the normal direction of the tapered surface of the sealing member, and the opening edge of the exterior body and the sealing member are more preferably pressed together through the second insulating member. Or, since they are closely connected, more suitable sealing can be achieved. Although this is just an example, the flange slope (angle α shown in FIG. 7) due to the "tapered surface" and/or "non-constant width dimension" of the sealing member 300 may be about 10° to 45°.

Installation of the sealing member through deformation of the brim portion leads to a reduction in the height of the sealing member. In other words, it is possible to design the sealing member and the battery structure related to it to be low-profile (in other words, the volume of such a part can be reduced), which is advantageous in terms of designing for expanding battery capacity. . In addition, when installing such a sealing member, even if there is a variation (for example, about 1 mm) in the thickness of the insulating member and/or the thickness of the exterior body (for example, the plate thickness of the lid-like member), it is possible to ensure sealing. Easy to plan. In other words, installation of the sealing member through deformation of the flange-like portion can easily accommodate variations in component parts, and therefore is excellent in mass productivity and can improve yield.

This is especially true when the exterior body opening is provided in the lid-like member of the exterior body, but it is possible to integrate the electrode terminal and the lid-like member before inserting the electrode assembly into the cup-shaped member of the exterior body, Only good products of the integrated lid-like member can be used in combination with the cup-like member of the exterior body, and in this respect as well, it is easy to improve the yield and/or the non-defective product rate.

Note that when providing the electrode terminal and the sealing member on the exterior body, the electrode terminal may be pressed together with the sealing member and the insulating member. Thereby, the electrode terminal, the sealing member, and the exterior body (for example, the lid-like member) can be more preferably integrated with each other by interposing the insulating member.

The sealing member used for manufacturing the secondary battery of the present invention preferably has a flat bottom surface (that is, the main surface 335B of the sealing member 300 located inside the exterior body), so that it is easy to weld. In other words, the main surface of the brim portion 335, which is provided as a flat surface, can be easily subjected to a suitable connection process. More specifically, as shown in FIG. 14, resistance welding (FIG. 14(A)), ultrasonic welding (FIG. 14(B)), and/or laser welding (FIG. 14(C)) are performed. Thus, the flat surface of the sealing member 300 and the conductive member 400 (for example, a "tab") can be connected relatively easily.

Note that although the sharp edge of the opening edge of the exterior body can be formed by forging, it can also preferably be obtained by shearing. Specifically, the sharp edge of the opening edge of the exterior body can be obtained by increasing the clearance set during the punching process. In a punching process 800 for forming an opening in the exterior body 100 as shown in FIG. When the lid-like member 100B) is subjected to a punching process (that is, subjected to punching), an opening of the exterior body can be formed and the edge forming the opening can be sharpened. Due to the larger "clearance", the shearing action from the punch in the punching direction becomes relatively larger in the inner circumferential direction (i.e., more radially inward) of the opening edge of the exterior body, causing local drag. This is because the edge portion extends so as to

The present invention can be embodied in various aspects. This will be explained below.

(Unsealing of common opening)
In this aspect, the sealing member provided in the common opening constituted by the terminal opening and the exterior body opening that are arranged concentrically with each other contributes to the above-mentioned release of the seal. Specifically, in the secondary battery of the present invention, the electrode terminal 200 may be arranged in the exterior body 100 such that the terminal opening 220 and the exterior body opening 150 are concentric with each other or form concentric circles. A sealing member 300 may be arranged for the common opening (see FIG. 5). In such a case, the sealing member is a deformable member that can be deformed in the common opening due to the increased cell internal pressure.

In other words, in the secondary battery according to the present embodiment, the electrode terminal has a terminal opening that overlaps with the opening of the exterior body, and the sealing member provided so as to close the opening of the exterior body through the terminal opening overlaps the opening of the exterior body. Due to the increased internal cell pressure of the secondary battery, the shape of the opening of the exterior body can be changed to break the airtight condition. In the unsealing mechanism that involves such a common opening, only the sealing member that contributes to battery sealing, which is separate from the electrode terminal provided as an external output terminal but is separate from the terminal, is deformed during abnormal pressure increase. do. Therefore, predictability when the cell internal pressure increases excessively becomes high, and a more suitable battery design based on the deformation of the sealing member becomes possible. In other words, the unpredictability of the rupture mode of the outer casing when the cell internal pressure increases excessively can be avoided as much as possible, and the secondary battery of the present invention can be provided as a safer battery.

(Seal release mechanism considering cell internal pressure effect)
This embodiment relates to a configuration of a secondary battery in which the sealing release works more appropriately when the cell internal pressure increases excessively. In particular, the sealing release functions more suitably depending on the relationship between the sealing member and the conductive member connected thereto.

Specifically, the conductive member that electrically connects the electrode assembly and the sealing member to each other overlaps with the sealing member for bonding to a partial region of the main surface of the sealing member, and the conductive member electrically connects the electrode assembly and the sealing member to each other. The non-overlapping area on the main surface of the sealing member which is different from that of the first embodiment is caused by the specific shape of the electrically conductive member. The "non-overlapping region" is different from the "overlapping region" in that the action of the increased cell internal pressure is directly applied to the sealing member without going through the conductive member, and the sealing caused by the excessively increased cell internal pressure is Deformation of the member is more effectively assisted. The "principal surface" here refers to the main surface of the sealing member located inside the exterior body. Therefore, the main surface corresponds to the main surface of the flange-like part (i.e., the inner flange-like part) provided at the inner end of the axially long body in the sealing member, and to put it simply, it corresponds to the bottom surface of the sealing member. .

In such an embodiment, the "non-overlapping area" which does not provide for the joining of the electrically conductive member and the sealing member may be provided, in particular, by an opening provided in the electrically conductive member and/or by a width dimension of the electrically conductive member. This may be caused by the narrow shape of the conductive member, which has a relatively small width. As shown in the exemplary embodiment of FIG. 16, the conductive member 400 may have a through hole 440 as an opening in its tip region. In such a case, even if the tip region of the conductive member 400 is placed on the sealing member 300 for joining with the sealing member 300, the portion of the through hole 440 will not overlap with the sealing member 300 and will not be joined. Do not serve. As can be seen from the illustrated embodiment, when the joint between the conductive member 400 and the sealing member 300 is viewed from inside the battery, the opening shape of the conductive member 400 (i.e., the through hole 440) causes the sealing member 300 to The bottom surface (that is, the main surface 335B of the sealing member located inside the exterior body) is partially exposed. The exposed portion is directly affected by the increased cell internal pressure without going through the conductive member, and the deformation of the sealing member caused by the excessively increased cell internal pressure is more effectively assisted. This is the same even when the conductive member has a narrow shape. As shown in the exemplary embodiment of FIG. 16, for example, the distal end portion of the conductive member 400 has a narrow portion 460 whose width dimension is relatively reduced compared to other portions. Therefore, even if the distal end portion of the conductive member 400 is placed on the sealing member 300 for bonding with the sealing member 300, the periphery of the narrow portion 460 does not overlap with the sealing member 300 and is not provided for bonding. do not. That is, the exposed portion of the sealing member 300 around the narrow portion 460 also contributes to the effective internal pressure action exerted on the sealing member. As can be seen from the illustrated embodiment, when the joint between the conductive member 400 and the sealing member 300 is viewed from inside the battery, the sealing member is damaged due to the narrow shape of the conductive member 400 (i.e., the narrow portion 460). The bottom surface of 300 (that is, the main surface 335B of the sealing member located inside the exterior body) is partially exposed. The effect of the increased cell internal pressure is directly applied to this exposed portion without going through the conductive member, and the deformation of the sealing member caused by the excessively increased cell internal pressure is more effectively assisted. In the secondary battery according to a preferred embodiment of the present invention, the seal release functions more suitably due to the unique bonding form between the conductive member and the sealing member.

(Seal release mechanism by interference action)
This aspect also relates to a configuration of a secondary battery in which the sealing release works more appropriately when the cell internal pressure increases excessively. In particular, the sealing release functions more suitably depending on the relationship between the sealing member and the conductive member connected thereto.

Specifically, a conductive member that electrically connects the electrode assembly and the sealing member to each other is provided so as to straddle the sealing member positioned within the opening of the exterior body. In plan view of FIG. 16, the tip portion 470 of the conductive member 400 is located at the bottom surface (i.e., , and straddles the main surface 335B) of the sealing member located inside the exterior body. Further, as shown in the plan view of FIG. 16, the tip portion 470 (particularly the location 470' shown in the figure) of the conductive member 400 is inside the opening of the exterior body in the width direction of the conductive member 400 (the "b direction" in the drawing). The main surface 335B of the sealing member located inside the exterior body (that is, the main surface 335B of the sealing member located inside the exterior body) may be straddled. The main surface 335B corresponds to the main surface of the flange-like part 335 provided at one end 330 of the axial member in the sealing member 300 (i.e., the inner flange-like part 335 of the sealing member in the secondary battery); The conductive member may be configured to straddle the main surface of the brim portion 335 positioned within the opening of the exterior body. When an external force (especially an external force in the axial direction of the common opening from the inside of the battery to the outside of the battery) acts on the conductive member that straddles the sealing member, the conductive member acts on the insulating member 500 (especially The second insulating member 540) may be interfered with. Due to such interference, when the sealing member is deformed due to the action of increased cell internal pressure, stress tends to occur that causes the sealing member and the conductive member to separate from each other. In other words, as a result of the deformation stress of the sealing member due to the increased internal pressure of the cell, a force is exerted on the inner brim portion that moves toward the outside of the battery, and as a result, the conductive member connected to the sealing member also moves outward. Although a moving force is applied, the conductive member is interfered with by the insulating member (especially the second insulating member) on the edge of the opening of the exterior body, so the main surface 335B tends to move further outward due to deformation. Advantageously, a force may be created that causes the sealing member and the electrically conductive member whose movement is to be prevented to release each other. Accordingly, in a preferred embodiment, the sealing member whose bottom surface (i.e., the main surface of the sealing member located inside the exterior body) is deformed so as to move outward is finally unbonded with the conductive member, resulting in a more secure seal. Release may result. Since the release of the bond between the sealing member and the conductive member means electrical disconnection between the sealing member and the conductive member, undesirable events such as accidental short circuits after the seal is released are easily avoided.

Note that the conductive member and the sealing member do not need to be joined together in all of their overlapping regions. In other words, the conductive member and the sealing member may be electrically connected such that only a part of the area where the conductive member and the sealing member overlap each other is joined. Although this is merely an example, the electrically conductive member and the sealing member may be electrically connected to each other by a spot joint. In the case of such local bonding, the sealing member, which deforms when the cell internal pressure abnormally increases, is likely to be disconnected from the conductive member. From the point of view of such partial joining, for example, in a plan view as shown in FIG. 16, the conductive member and the sealing member are joined to each other only at local locations S in a spot manner.

(Secondary battery that is circular in plan view)
In this embodiment, the overall shape of the secondary battery in plan view is circular. In other words, the secondary battery 1000 has a button-shaped or coin-shaped external shape (for example, see FIG. 2).

The circular shape of a secondary battery in plan view means that the shape of the electrode assembly and/or the exterior body containing it is circular when viewed from above or below. There is.

The term "circular" here is not limited to a complete circle (i.e., simply a "circle" or a "perfect circle"), but may be normally included in a "round shape" as recognized by those skilled in the art, even though it may be modified. It also includes a substantially circular shape. For example, it may not only be a circle or a perfect circle, but also the curvature of its arc may be locally different, and it may also be a shape derived from a circle or a perfect circle, such as an ellipse. As a typical example, a battery having such a circular shape in plan view corresponds to a so-called button-shaped or coin-shaped battery.

In a secondary battery that has a circular shape in plan view, the shape of the opening of the exterior body in plan view may be circular, and the shape of the terminal opening in plan view may also be circular (the circular shape here may also be circular). (It is synonymous with the circular shape described regarding the plan view shape of the secondary battery). In such a case, in the present invention, the outline of the exterior body in plan view (especially the outline of the part forming the outer edge) is circular, and the outline of the electrode terminal and/or the sealing member in plan view (particularly the outline of the part forming the outer edge) is circular. It may be circular.

In a preferred embodiment, since the secondary battery is button-shaped or coin-shaped, the dimension in the axial direction (for example, the normal direction or perpendicular direction to the main surface of the battery) is smaller than the width dimension (diameter dimension). However, the secondary battery of the present invention is not limited to this, and the dimension of the secondary battery in the axial direction (for example, the normal direction or perpendicular direction to the main surface of the battery) is the same as the width dimension (diameter dimension), or is comparable to the width dimension (diameter dimension). It may become larger.

(Disc-shaped electrode terminal)
In this embodiment, the overall shape of the electrode terminal is disc-shaped. To put it simply, the electrode terminal is a metal disc, making it more suitable for the above-mentioned button-type or coin-type batteries.

For example, the disc-shaped electrode terminal 200 may have a shape as shown in FIG. The electrode terminal 200 has a terminal opening 220 at its center. As described above, the terminal opening 220 is preferably provided to align or align with the exterior body opening 150 of the exterior body 100, and the sealing member 300 closes the exterior body opening 150 through the terminal opening 220. It has become.

The electrode terminal may include a gas vent opening in addition to the terminal opening. For example, as shown in FIG. 17, the electrode terminal 200 may include at least one gas release opening 250 in the circumferential direction when viewed from above. The gas release opening 250 corresponds to an opening through which gas inside the exterior body can pass when the sealing member is deformed due to the increased cell internal pressure and the sealed state of the exterior body is released. In the electrode terminal 200, the inner region 240, which is inside the gas vent opening 250 in the width direction, is opposite to the gas vent opening 250 so that the gas generated in the cell can reach the gas vent opening 250 from the inside of the exterior body more smoothly. It may have a raised shape. In other words, the electrode terminal 200 may have a configuration in which the inner region 240 including the central region is positioned at a higher level than the peripheral region 270 on the outer side in the width direction. Due to the inner region 240 located at a relatively high level, a gap is preferably provided between the electrode terminal and the insulating member (in particular the first insulating member). Therefore, the internal gas of the exterior body can flow to the gas release opening 250 through this gap when the seal is released, and the internal gas can eventually easily escape to the outside of the battery.

Although the embodiments of the present invention have been described above, these are merely typical examples. Therefore, those skilled in the art will readily understand that the present invention is not limited thereto and that various embodiments are possible.

For example, in the above description, a button-shaped or coin-shaped secondary battery as shown in FIGS. 2 and 17 has been mentioned as a secondary battery, but the present invention is not necessarily limited to this. In other words, the exterior body is not limited to a so-called cylindrical can type exterior body, but may be a square can or irregularly shaped can type exterior body.

The secondary battery of the present invention may be, for example, a square secondary battery (see, for example, FIG. 18). In other words, the shape of the secondary battery 1000 in plan view is not limited to a circle, but may be a square, a rectangle, or the like.

Moreover, although the embodiment in which the exterior body is comprised of a cup-shaped member and a lid-shaped member has been described above, the present invention is not necessarily limited to this. For example, the exterior body may be composed of cup-shaped members. That is, the first metal exterior body and the second metal exterior body may each be a cup-shaped member. In other words, the exterior body may be composed of at least a first metal exterior body that is a cup-shaped member and a second metal exterior body that is also a cup-shaped member. In this case, the first metal exterior body and the second metal exterior body of the cup-shaped member may be combined so that their side walls are aligned with each other to form the exterior body. The cup-shaped member of either the first metal exterior body or the second metal exterior body may be provided with the above-mentioned “exterior body opening”, and therefore, the electrode terminal and the sealing member may be provided with respect to the cup-shaped member. It's okay to be rejected. Furthermore, although it has been mentioned that when the exterior body is composed of a cup-like member and a lid-like member, the exterior body opening is provided in the lid-like member, the present invention is not necessarily limited thereto. An exterior opening may be provided in the cup-shaped member.

Moreover, although the embodiment in which the sealing member has a flange-like portion on both one end side and the other end side of the axially long body portion has been described above, the present invention is not necessarily limited to this. The flange-like portion may be provided only on one end side of the axially elongated body portion, or the flange-like portion may be provided only on the other end side of the axially elongated body portion. In such a case, it can be said that the flange-like portion is provided on at least one of one end side and the other end side of the axially long body portion. Note that the aspect regarding the flange-like portion can also be expressed from another perspective. For example, in the secondary battery of the present invention, it can be said that the sealing member preferably includes flange-shaped portions (i.e., one flange portion and the other flange portion) that face each other so that the axially long body portion is interposed therebetween. . Alternatively, in the secondary battery of the present invention, the sealing member preferably includes a flanged portion as an end portion thereof, and more preferably includes flanged portions facing each other (i.e., one flanged portion and the other flanged portion). It can be said that

Furthermore, in the above description, when the insulating member is composed of a first insulating member and a second insulating member, the second insulating member 540 having the form shown in FIG. 7 has been mentioned, but the present invention is not necessarily limited to this. Not done. The second insulating member 540 that extends beyond the edge 155a of the opening edge 155 may extend further to the outside as shown in FIG. 19. That is, the second insulating member 540 may have a shape in which the protruding portion 545 is expanded to the outer side in the battery width direction. In such a case, it is easy to avoid an event in which the conductive member comes into contact with the exterior body (for example, a lid-like member) after the sealing member that deforms when the cell internal pressure abnormally increases breaks the connection with the conductive member. This makes it easier to reduce risks such as short circuits. Further, such a second insulating member extending more widely in the battery width direction serves as an insulator to prevent the electrode assembly from conducting electricity to the exterior body (particularly a lid-like member having an exterior body opening). This also contributes to the realization of safer secondary batteries.

Furthermore, in the above description, the main surface of the sealing member located inside the exterior body (i.e., the inner main surface of the sealing member) is smaller than the opening of the exterior body, but the outer main surface of the sealing member is not necessarily limited to this. That is, the main surface of the sealing member located on the outside of the exterior body (ie, the outer main surface) may or may not be smaller than the exterior body opening. For example, the outer major surface 365A (see FIG. 4) of the sealing member may be smaller than the exterior body opening, like the inner major surface, or may be larger than the exterior body opening, unlike the inner major surface. In other words, when the sealing member has an inner flange and an outer flange, the width or area of the outer flange may be smaller than the width or area of the exterior body opening; The width or area of the opening may be larger than the width or area of the opening of the exterior body. In addition, if both the inner flanged part and the outer flanged part are smaller than the width of the opening of the exterior body, the entire sealing member may have a width smaller than the opening of the exterior body, and any part of the sealing member The width dimension of the opening may be smaller than the width dimension of the opening of the exterior body.

It should be added for confirmation that the present invention described above can correspond to at least one of the following items as a certain preferred embodiment.

- Since the sealing member (that is, the sealing member) can be provided on the battery by pressing, productivity is good and processing costs can be easily reduced. Note that the sealing member may be deformed by pressing and then provided on the battery.
- The joint surface of the conductive member (for example, a tab) can be easily provided as a flat surface, making tab joining easier and improving quality.
- Any welding method such as laser welding, ultrasonic welding, and/or resistance welding can be used to join the conductive members (for example, tabs).
・The safety valve provided as a gas release safety function is required to be easily ruptured when the cell internal pressure rises abnormally, but it is also required that it not be easily ruptured when an impact load such as a fall is applied. In this regard, since the sealing member of the present invention is made of metal, it is not affected by some impact, and gas venting can function stably under assumed abnormal internal pressure.
- Regarding the degassing safety function, the breaking strength in the event of an abnormal rise in cell internal pressure can be determined by the thickness of the flange of the insulating member. Preferably, by adjusting the thickness of the second insulating member (particularly the thickness of the flange portion corresponding to the protrusion), the tearing pressure in an abnormal state can be adjusted. Since the second insulating member is preferably a resin member, the breaking force can be smaller than that of metal breaking. In other words, gas can be vented more quickly in response to an abnormal increase in internal pressure, making it easier to provide a safer battery.
- Since the sealing member can press the insulating member during installation, the sealing performance can be improved, and while providing such sealing performance, it is easy to add a safety function that can reduce the internal pressure when the cell internal pressure rises abnormally.
- For example, a spin crimping machine may be used to press the sealing member during installation, but a press crimping machine may also be used.
・Since the sealing structure does not require welding, manufacturing costs are low. For example, since there is no need to obtain a sealing structure by welding using ultrasonic waves or laser, problems such as contamination and spatter scattering are less likely to occur. Furthermore, since there is no need to use resistance welding for sealing, troubles due to abnormal discharge during welding are less likely to occur. Furthermore, it is not a sealing structure based on bonding using an adhesive. Bonding using such an adhesive requires a separate adhesive applicator, which increases manufacturing costs.
・The degree of freedom in the shape of the insulating member is large. By using an insulating member that extends largely in the outer diameter direction, the physical distance between the positive electrode and the negative electrode on the outside of the outer can can be further increased, making it easier to avoid short circuits.
- By increasing the size of the insulating member, the electrode terminal that is electrically connected to the sealing member can also be made larger (larger in the width direction or radial direction).
- There is no need for special work on the lid-like member provided as the exterior body, or such work is reduced. In other words, the lid member of the exterior body and the cup member may be joined by laser welding or crimping, and there are no particular limitations.
・Since the sealing member before installation has a shape that can be mass-produced, it is suitable for mass production and can contribute to cost reduction. For example, the sealing member can be easily obtained by rolling, and can be obtained at a relatively low cost.
・It is possible to conduct electricity between the positive and negative electrodes only on the top surface of the battery.
- The electrode terminal and the insulating member (for example, gasket) have a relatively high degree of freedom in design, and the size of the electrode terminal and/or the insulating member can be arbitrarily changed according to the installation location.
- The material of the electrode terminal does not necessarily have to be the same as that of the sealing member, and can be selected arbitrarily (although this is just an example, SUS material and/or plated SPP material may be used as the material of the electrode terminal).
- When the cell internal pressure rises abnormally, the second insulating member is cut off as the sealing member undergoes buckling deformation, and can move outward together with the flange-shaped portion at the inner end of the sealing member. Some of the cut pieces of the second insulating member that have not moved (particularly the cut pieces of the insulating member located on the relatively outer side) remain in their original positions, and therefore preferably act to prevent the conductive member from moving. Therefore, it is possible to more reliably prevent the electrically disconnected connection between the conductive member and the sealing member.
・The heat resistance of a battery substantially depends on the heat resistance of the insulating member, and if an insulating member with high heat resistance is used, the sealing heat resistance characteristics of the battery can be improved (for example, using an insulating member such as PPS) engineering plastics, thermoplastics, or thermosetting resins).
・Since an insulating member is provided between the electrode terminal and the exterior body, electrical insulation with the exterior body corresponding to the exterior case can be more reliably achieved, and electrical short-circuits caused by contact with the electrode assembly can be achieved. Since concerns about this are reduced, it is easier to create an electrically safer design.
- A sealing member can be placed inside the opening of the exterior body. That is, it is possible to suppress the protrusion of the sealing member from the electrode terminal, and it is easy to achieve a low-profile design. Furthermore, since the sealing member can be provided within the opening of the exterior body without any protrusion, even if an impact load such as a drop is applied to the battery, almost no load is applied to the sealing member. Therefore, a shearing force sufficient to cause breakage of the insulating member is unlikely to occur due to a drop impact, etc., and a safer battery is likely to be obtained.
- The thickness of the exterior body (for example, the plate thickness of the lid-like member) is approximately 0.005 mm or more and 2 mm or less, which can accommodate up to the processing limit for changing the height of the sealing member.
- Since the sealing member deforms to buckle when the cell internal pressure rises excessively, the distance between the conductive member and the sealing member after pressure reduction can be more reliably maintained. In other words, in a preferred embodiment, when the pressure is reduced, the electrical connection between the conductive member and the sealing member can be more reliably broken, and the electrical connection between the sealing member and the conductive member is substantially unaffected by the later battery position. Undesired reconnection is likely to be prevented.
・The joint point between the sealing member and the conductive member is located at the center of the sealing member, and the conductive member is supported by the insulating member (especially the second insulating member) on the opening edge of the exterior body at a position equidistant from the center. If this is done, the insulating member will provide suitable resistance to the conductive member when the cell internal pressure rises abnormally, and the sealing member will be easily released from the conductive member as desired.
- The insulating member and the electrode terminal can be fixed to each other by providing a lateral groove on the inner periphery of the insulating member into which the electrode terminal fits, and by fitting a part of the outer periphery of the electrode terminal into the lateral groove. For such immobilization, it is sufficient to provide an outer peripheral protrusion of the electrode terminal and provide a notch in the insulating member in which the protrusion can be placed. In such a case, insert the outer peripheral protrusion of the electrode terminal into the notch of the insulating member at a position where they do not interfere with each other, then rotate the electrode terminal and the insulating member relative to each other, and insert the protruding part of the electrode terminal into the horizontal groove of the insulating member. By fitting the tension part, the electrode terminal and the insulating member can be firmly combined relatively easily. The productivity of fixing the electrode terminal and the insulating member in this manner is relatively high because the assembly is performed by rotational fitting. Furthermore, it becomes easy to disassemble the battery for analysis when an abnormality occurs. Furthermore, since it is fixed without using an adhesive, there is virtually no fear of damage during disassembly.

Aspects of the secondary battery of the present disclosure are as follows.
<1> Comprising an electrode assembly and an exterior body housing the electrode assembly,
The electrode terminal provided in the exterior opening of the exterior body includes a sealing member for sealing the exterior body, and the main surface of the sealing member located inside the exterior body is larger than the exterior body opening. The secondary battery is small in size, and the sealing member that closes the opening of the exterior body is a deformable member that can be deformed due to a pressing force.
<2> The secondary battery according to <1>, wherein the sealing member includes an axially long body portion whose height is larger than its width.
<3> The secondary battery according to <1> or <2>, wherein the deformation of the sealing member is based on deformation of the axially long body.
<4> The secondary battery according to <2> or <3>, wherein the secondary battery has a hollow region around the axially long body portion of the sealing member.
<5> The secondary battery according to any one of <1> to <4>, wherein the electrode terminal and the electrode assembly are electrically connected to each other via the sealing member.
<6> The method according to any one of <1> to <5>, wherein the sealing member has a flange-like part, and the main surface of the sealing member is provided in the flange-like part. Next battery.
<7> The secondary battery according to <6>, wherein the width of the brim portion is non-uniform.
<8> The secondary battery according to <6> or <7>, wherein the side surface of the brim portion has a tapered surface.
<9> Any one of <1> to <8>, wherein the electrode terminal has a terminal opening that overlaps with the opening of the exterior body, and the sealing member positioned in the terminal opening closes the opening of the exterior body. The secondary battery described in item 1.
<10> The secondary battery according to any one of <1> to <9>, wherein the pressing force is caused by increased cell internal pressure of the secondary battery.
<11> The secondary battery according to any one of <1> to <10>, wherein the outer casing opening edge forming the outer casing opening has a sharp edge.
<12> The secondary battery according to any one of <1> to <11>, wherein an insulating member is provided between the exterior body opening edge forming the exterior body opening and the sealing member.
<13> The electrode terminal has a terminal opening that overlaps with the opening of the exterior body, and the sealing member positioned in the terminal opening and closing the opening of the exterior body closes the exterior body due to the pressing force. The secondary battery according to any one of <1> to <12>, wherein the deformation occurs so as to cause rupture of an insulating member provided at the edge of the opening of the exterior body that forms the opening.
<14> The secondary battery according to <12> or <13> subordinate to <12>, wherein the opening edge of the exterior body has a sharp edge, and the sharp edge assists in the breaking of the insulating member. .
<15> A first insulating member provided between the electrode terminal and the exterior body, and a second insulating member provided between the exterior body opening edge forming the exterior body opening and the sealing member. The insulating member is made up of
The secondary battery according to any one of <1> to <14>, wherein the opening edge of the exterior body and the sealing member are pressed against each other via the second insulating member.
<16> The secondary battery according to <15>, wherein the sealing member deforms so as to cause rupture to the second insulating member due to the increased cell internal pressure of the secondary battery.
<17> The secondary battery according to any one of <1> to <16>, wherein the exterior body includes a cup-shaped member and a lid-shaped member, and the lid-shaped member has the exterior body opening. .
<18> The conductive member that electrically connects the electrode assembly and the sealing member to each other is configured to straddle the sealing member positioned within the opening of the exterior body, <1> to <17 ＞The secondary battery according to any one of ＞.
<19> A conductive member that electrically connects the electrode assembly and the sealing member to each other overlaps the sealing member for bonding to a partial region of the main surface of the sealing member,
The non-overlapping region of the main surface other than the partial region is formed by an opening provided in the conductive member and/or a narrow portion of the conductive member where the width dimension of the conductive member is relatively small. The secondary battery according to any one of <1> to <18>, which is provided.
<20> The secondary battery according to any one of <1> to <19>, wherein the electrode of the electrode assembly includes a positive electrode and a negative electrode capable of inserting and extracting lithium ions.

The secondary battery according to the present invention can be used in various fields where power storage is expected. Although this is just an example, the secondary battery of the present invention can be used in the electrical, information, and communication fields where electrical and electronic devices are used (e.g., mobile phones, smartphones, notebook computers, digital cameras, activity meters, arm computers, etc.). , electronic paper, wearable devices, RFID tags, card-type electronic money, small electronic devices such as smart watches, and mobile device fields), household and small industrial applications (e.g., power tools, golf carts, household/nursing care/industrial robots), large industrial applications (e.g., forklifts, elevators, harbor cranes), transportation systems (e.g., hybrid vehicles, electric vehicles, buses, trains, electric assist) Bicycles, electric motorcycles, etc.), power system applications (e.g., various power generation, road conditioners, smart grids, home-installed power storage systems, etc.), medical applications (medical equipment such as earphones and hearing aids), and pharmaceutical applications. (in the field of medication management systems, etc.), as well as in the IoT field, and space/deep sea applications (for example, in the fields of space probes, underwater research vessels, etc.).

1 Positive electrode 2 Negative electrode 5 Electrode constituent layer 10 Electrode assembly 100 Exterior body 100A Cup-shaped member 100B Lid-like member 130 Peripheral area of exterior body 150 Exterior body opening 155 Exterior body opening edge 155a Edge of exterior body opening edge 200 Electrode terminal 200A Electrode Outer main surface of the terminal 220 Terminal opening 225 Terminal opening edge 240 Inner region of the electrode terminal 250 Opening for gas release 270 Peripheral region of the electrode terminal 300 Sealing member 330 One end 335 Flange-shaped portion at one end 335A Sealing member Tapered surface 335A' Tapered contour of the sealing member 335B Inner main surface (bottom surface) of the sealing member/main surface of the flanged portion on one end side 350 Long shaft body portion 360 Other end portion 365 Flange portion at the other end 365A Outer main surface (top surface) of the sealing member/main surface of the flanged portion on the other end side 366 Stepped portion of the flanged portion at the other end 400 Conductive member 410 Top surface of the conductive member 440 Through hole 460 Narrow portion 470 Tip portion of the conductive member 470' Portion where the conductive member straddles the opening of the exterior body in the width direction 500 Insulating member 520 First insulating member (for example, outer insulating member)
540 Second insulating member (e.g. inner insulating member)
545 Projection provided on second insulating member 1000 Secondary battery P Cell internal pressure L _O Opening dimension of exterior body opening in plan view L Width dimension of inner main surface of _W sealing member

Claims (20)

It comprises an electrode assembly and an exterior body housing the electrode assembly,
an electrode terminal provided in an opening of the exterior body includes a sealing member for sealing the exterior body;
The main surface of the sealing member located inside the exterior body is smaller than the exterior body opening, and the sealing member that closes the exterior body opening is a deformable member that can be deformed due to a pressing force. It is a secondary battery. The secondary battery according to claim 1, wherein the sealing member includes an axially long body portion whose height is larger than its width. The secondary battery according to claim 2, wherein the deformation of the sealing member is based on deformation of the axially long body. The secondary battery according to claim 2, wherein the secondary battery has a hollow region around the axially long body portion of the sealing member. The secondary battery according to claim 1, wherein the electrode terminal and the electrode assembly are electrically connected to each other via the sealing member. The secondary battery according to claim 1, wherein the sealing member has a flange-shaped portion, and the main surface of the sealing member is provided on the flange-shaped portion. The secondary battery according to claim 6, wherein the width of the brim portion is non-uniform. The secondary battery according to claim 6, wherein a side surface of the brim portion is a tapered surface. The secondary battery according to claim 1, wherein the electrode terminal has a terminal opening that overlaps with the opening of the outer case, and the sealing member positioned in the terminal opening closes the opening of the outer case. The secondary battery according to any one of claims 1 to 9, wherein the pressing force is caused by increased cell internal pressure of the secondary battery. The secondary battery according to any one of claims 1 to 9, wherein the outer case opening edge forming the outer case opening has a sharp edge. 2. The secondary battery according to claim 1, wherein an insulating member is provided between an edge of the exterior body opening that forms the exterior body opening and the sealing member. The electrode terminal has a terminal opening that overlaps with the exterior body opening, and the sealing member positioned in the terminal opening and closing the exterior body opening forms the exterior body opening due to the pressing force. The secondary battery according to claim 1, wherein the deformation occurs so as to cause breakage of an insulating member provided at an edge of an opening of the exterior body. The secondary battery according to claim 13, wherein the opening edge of the outer case has a sharp edge, and the sharp edge assists in the breaking of the insulating member. Consisting of a first insulating member provided between the electrode terminal and the exterior body, and a second insulating member provided between the exterior body opening edge forming the exterior body opening and the sealing member. It comprises an insulating member,
The secondary battery according to claim 1, wherein the opening edge of the exterior body and the sealing member are pressed against each other via the second insulating member. 16. The secondary battery according to claim 15, wherein the sealing member deforms so as to cause breakage to the second insulating member due to the pressing force. The secondary battery according to any one of claims 1 to 9, wherein the exterior body includes a cup-shaped member and a lid-shaped member, and the lid-shaped member has the exterior body opening. Any one of claims 1 to 9, wherein a conductive member that electrically connects the electrode assembly and the sealing member to each other is provided so as to straddle the sealing member positioned within the opening of the exterior body. The secondary battery described in . A conductive member that electrically connects the electrode assembly and the sealing member to each other overlaps the sealing member for joining with a partial region of the main surface of the sealing member,
The non-overlapping region of the main surface other than the partial region is formed by an opening provided in the conductive member and/or a narrow portion of the conductive member where the width dimension of the conductive member is relatively small. A secondary battery according to any one of claims 1 to 9. The secondary battery according to any one of claims 1 to 9, wherein the electrodes of the electrode assembly include a positive electrode and a negative electrode capable of intercalating and deintercalating lithium ions.

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