Secondary batteries

Abstract

The present invention provides a secondary battery which comprises: an electrode assembly; an outer package that contains the electrode assembly; and an electrode terminal that is provided on the outer package and is electrically connected to the electrode assembly via a conductive member. With respect to this secondary battery, the electrode terminal and the outer package are bonded to each other by means of an insulating sealing member that is provided around an opening of the outer package, while being interposed between the electrode terminal and the outer package, through the opening the conductive member passing; when viewed in plan, the outline of a surface of the electrode terminal, the surface being in contact with the insulating sealing member, is composed of both a linear part and a curved part; when viewed in plan, the outline of a surface of the outer package, the surface being in contact with the insulating sealing member, includes a curvature; and the curved part of the electrode terminal and a part of the curvature of the outer package face each other.

Description

[Technical Field]

[0001] The present invention relates to a secondary battery. More particularly, to a secondary battery comprising an electrode assembly consisting of electrode constituent layers including a positive electrode, a negative electrode, and a separator. [Background technology]

[0002] Rechargeable batteries, being rechargeable batteries, can be repeatedly charged and discharged and are used in a variety of applications. For example, rechargeable batteries are used in mobile devices such as cell phones, smartphones, and laptop computers. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2019-046639 [Patent Document 2] Japanese Patent Publication No. 2020-202071 [Overview of the project] [Problems that the invention aims to solve]

[0004] A secondary battery comprises an electrode assembly in which electrode constituent layers, including a positive electrode, a negative electrode, and a separator between them, are stacked, as well as an outer casing that encloses the electrode assembly. In such a secondary battery, it is conceivable to provide a rupture mechanism in anticipation of situations such as an increase in internal cell pressure. This is to prevent more serious accidents such as unintended battery explosions.

[0005] On the other hand, secondary batteries require external terminals for electrical connection to the outside world in order to be used.

[0006] The inventors of this application diligently investigated whether there was still room for development of a battery configuration that could satisfy both the installation of external terminals and the installation of a detachment mechanism. As a result, they found that there is still room for development of a battery configuration that satisfies both the detachment mechanism and the installation of terminals.

[0007] This invention has been made in view of the above-mentioned problems. That is, the main object of this invention is to provide a new battery configuration in terms of the cracking mechanism and terminal installation. [Means for solving the problem]

[0008] The inventor of this application attempted to solve the above-mentioned problems not by simply extending the existing technology, but by taking a new approach. As a result, the inventor arrived at the invention of a secondary battery that achieves the above-mentioned main objective.

[0009] The secondary battery according to the present invention electrode assembly, An outer casing for housing the electrode assembly, and Electrode terminals arranged on the exterior body and electrically connected to the electrode assembly via conductive members. It consists of having, The electrode terminal and the outer casing are bonded together by an insulating sealing member interposed between them and provided around the opening in the outer casing through which the conductive member passes. The plan view contour of the electrode terminal on the surface in contact with the insulating seal member consists of both a straight portion and a curved portion, the plan view contour of the outer casing on the surface in contact with the insulating seal member includes a curve, and the curved portion of the electrode terminal and a part of the curve of the outer casing face each other. [Effects of the Invention]

[0010] In the secondary battery according to the present invention, the battery configuration related to both the terminal installation and the cleavage mechanism is a configuration not seen before. As a result, it is easier to provide an external lead-out member for external connection, and a more suitable cleavage mechanism is likely to be provided. More specifically, when the planar view contour of the electrode terminal is composed of both a straight portion and a curved portion, it becomes easier to secure the ratio of the planar view area of the non-terminal region on the main surface of the battery compared to the case where it does not have such a contour configuration of the electrode terminal. Therefore, it becomes easier to provide an external lead-out member for the non-terminal region, and the secondary battery of the present invention is more likely to be provided as a more suitable battery. Further, when a pressing force is generated due to an abnormal increase in the internal pressure of the exterior body or the like, the electrode terminal can be cleaved so as to open to prevent an unintended battery explosion. In the secondary battery of the present invention, such cleavage is relatively likely to occur from the "straight portion". That is, it is easy for the electrode terminal to cleave so as to open from the straight portion in the planar view contour of the electrode terminal, and the predictability at the time of an abnormal increase in the cell internal pressure can be improved.

Brief Description of the Drawings

[0011] [Figure 1] FIG. 1 is a cross-sectional view schematically showing an electrode configuration layer (FIG. 1(A): planar lamination structure, FIG. 1(B): wound structure). [Figure 2] FIG. 2 is a perspective view schematically showing the appearance of a secondary battery according to an embodiment of the present invention. [Figure 3] FIG. 3 is a schematic view of a secondary battery according to an embodiment of the present invention (FIG. 3(A): cross-sectional view, FIG. 3(B): semi-segmented perspective view). [Figure 4] FIG. 4 is a schematic view showing representative elements constituting a secondary battery according to an embodiment of the present invention. [Figure 5] FIGS. 5(A) to 5(D) are schematic views respectively showing a planar view of the main surface of a secondary battery according to an embodiment of the present invention. [Figure 6] FIGS. 6(A) to 6(D) are schematic views respectively showing the planar view contour of an electrode terminal according to an embodiment of the present invention together with the planar view contour of the exterior body. [Figure 7]Figures 7(A) to 7(D) are schematic diagrams showing the plan view contours of electrode terminals according to one embodiment of the present invention. [Figure 8] Figure 8 is a schematic diagram showing the plan view contour of an electrode terminal according to one embodiment of the present invention. [Figure 9] Figures 9(A) to 9(D) are schematic diagrams showing the plan view contour of an exterior body according to one embodiment of the present invention. [Figure 10] Figure 10 is a schematic diagram showing a configuration related to the opening in the outer casing of a secondary battery according to one embodiment of the present invention. [Figure 11] Figure 11 is a schematic diagram illustrating the venting mechanism to which the present invention relates. [Figure 12] Figures 12(A) to 12(D) are schematic diagrams showing the plan view contour of an insulating sealing member according to one embodiment of the present invention. [Figure 13] Figure 13 is a schematic diagram illustrating the deflection or strain of the outer casing when the internal pressure of the cell rises abnormally. [Figure 14] Figures 14(A) and 14(B) are schematic perspective views illustrating the "installation configuration of the external lead-out member". [Figure 15] Figures 15(A) and 15(B) are schematic diagrams illustrating the base virtual battery assumed in the [Examples]. [Figure 16] Figure 16(A) is a schematic diagram modeling the configurations of the example and comparative example, respectively, and Figure 16(B) is a schematic diagram showing the non-terminal area related to these modeled configurations. [Figure 17] Figure 17 is a graph showing the results of the simulation. [Modes for carrying out the invention]

[0012] The following describes in more detail a secondary battery according to one embodiment of the present invention. While the description will refer to the drawings as necessary, the various elements in the drawings are shown schematically and illustratively for the purpose of understanding the present invention, and their appearance and / or dimensional ratios may differ from the actual product. The secondary battery described below is intended to embody the technical concept of the present invention, and unless otherwise specified, the present invention is not limited to the following. For convenience, in order to explain the key points or facilitate understanding, the description may be divided into embodiments and examples, but partial substitution or combination of configurations shown in different embodiments is possible. In descriptions of such embodiments, descriptions of matters common to the preceding description may be omitted, and only the differences may be described. In particular, similar effects and benefits from similar configurations may not be mentioned sequentially for each embodiment.

[0013] The “cross-sectional view” described directly or indirectly in this specification is based on a hypothetical cross-section of a secondary battery obtained by cutting it along the stacking direction of the electrode assemblies or electrode layers constituting the secondary battery. The direction of “thickness” described directly or indirectly in this specification is based on the stacking direction of the electrode materials constituting the secondary battery or the direction along the winding axis of a winding stacked structure. For example, in the case of a “plate-shaped secondary battery with thickness,” such as a button-type or coin-type battery, the direction of “thickness” may correspond to the plate thickness direction of such secondary battery. Furthermore, a “plan view” may correspond to a figure obtained when an object is viewed along the normal or perpendicular direction of its main surface (e.g., the upper surface).

[0014] In this specification, “up and down” and “left and right” as used directly or indirectly correspond to the up and down and left and right directions in the figures, respectively. Unless otherwise specified, the same reference numeral or symbol indicates the same member or part or has the same meaning. In a preferred embodiment, the vertical downward direction (i.e., the direction in which gravity acts) can be considered as “downward,” and the opposite direction as “upward.”

[0015] The various numerical ranges referred to herein are intended to include the lower and upper limits themselves, unless otherwise specified. Terms such as “approximately,” “to a certain extent,” and “constant” mean that they may include variations or differences of a few percent, for example, ±10%.

[0016] [Basic configuration of a secondary battery] In this specification, "secondary battery" refers to a battery that can be repeatedly charged and discharged. Therefore, the secondary battery according to the present invention is not overly bound by its name, and may also include, for example, energy storage devices.

[0017] The secondary battery according to the present invention comprises an electrode assembly formed by stacking electrode constituent layers including a positive electrode, a negative electrode, and a separator. Figures 1(A) and 1(B) illustrate an electrode assembly 10. As shown, the positive electrode 1 and the negative electrode 2 are stacked via a separator 3 to form an electrode constituent layer 5, and at least one such electrode constituent layer 5 is stacked to form the electrode assembly 10. In Figure 1(A), the electrode constituent layer 5 is stacked in a planar manner without being wound, resulting in a planar stacked structure. On the other hand, in Figure 1(B), the electrode constituent layer 5 is wound in a wound manner, resulting in a wound structure. That is, in Figure 1(B), the electrode constituent layer 5, including the positive electrode 1, the negative electrode 2, and the separator 3 placed between the positive electrode 1 and the negative electrode 2, is wound in a roll shape, resulting in a wound structure. In a secondary battery, such an electrode assembly is sealed in an outer casing together with an electrolyte (e.g., a non-aqueous electrolyte). Note that the structure of the electrode assembly is not necessarily limited to a planar stacked structure or a wound structure. For example, the electrode assembly may have a so-called stack-and-fold structure in which the positive electrode, separator, and negative electrode are laminated on a long film and then folded.

[0018] The positive electrode consists of at least a positive electrode material layer and a positive electrode current collector. In the positive electrode, the 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, multiple positive electrodes in an electrode assembly may each have a positive electrode material layer provided on both sides of the positive electrode current collector, or they may each have a positive electrode material layer provided on only one side of the positive electrode current collector.

[0019] The negative electrode consists of at least a negative electrode material layer and a negative electrode current collector. In the negative electrode, the 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, multiple negative electrodes in an electrode assembly may each have a negative electrode material layer provided on both sides of the negative electrode current collector, or they may each have a negative electrode material layer provided on only one side of the negative electrode current collector.

[0020] The electrode active materials contained in the positive and negative electrodes, i.e., the positive electrode active material and the negative electrode active material, are substances that directly participate in the transfer of electrons in a secondary battery and are the main materials of the positive and negative electrodes that carry out charging and discharging, i.e., the battery reaction. 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 move between the positive and negative electrodes to transfer electrons and perform charging and discharging. The positive electrode material layer and the negative electrode material layer may be layers that can intercept and deintercept lithium ions. In other words, the secondary battery according to the present invention may be a non-aqueous electrolyte secondary battery in which lithium ions move between the positive and negative electrodes via a non-aqueous electrolyte to perform charging and discharging of 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 that can intercept and deintercept lithium ions as the positive electrode and negative electrode.

[0021] The positive electrode active material of the positive electrode material layer is composed of, for example, granular material, and a binder may be included in the positive electrode material layer to ensure sufficient contact between particles and maintain their shape. Furthermore, a conductive additive may be included in the positive electrode material layer to facilitate the transfer of electrons that drive the battery reaction. Similarly, the negative electrode active material of the negative electrode material layer is composed of, for example, granular material, and a binder may be included to ensure sufficient contact between particles and maintain their shape, and a conductive additive may be included in the negative electrode material layer to facilitate the transfer of electrons that drive the battery reaction. Because of this form containing multiple components, the positive electrode material layer and the negative electrode material layer can also be referred to as the "positive electrode composite layer" and the "negative electrode composite layer," respectively.

[0022] The positive electrode active material may be a substance that contributes to the intercalation and deintercalation of lithium ions. From this viewpoint, 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. In other words, in the positive electrode material layer of the secondary battery according to the present invention, such a lithium transition metal composite oxide is preferably included as the positive electrode active material. For example, the positive electrode active material may be lithium cobaltate, lithium nickelate, lithium manganeseate, lithium iron phosphate, or a part of these transition metals replaced with another metal. Such positive electrode active materials may be included as a single type, or two or more types may be included in combination.

[0023] The binder that may be included in the positive electrode material layer is not particularly limited, but at least one selected from the group consisting of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, and polytetrafluoroethylene can be mentioned. The conductive additive that may be included in the positive electrode material layer is not particularly limited, but at least one selected from the group consisting of carbon black such as thermal black, furnace black, channel black, Ketjen black, and acetylene black, graphite, carbon fibers such as carbon nanotubes and vapor-grown carbon fibers, metal powders such as copper, nickel, aluminum, and silver, and polyphenylene derivatives can be mentioned.

[0024] The thickness of the positive electrode material layer is not particularly limited, but may be between 1 μm and 300 μm, for example, between 5 μm and 200 μm. The thickness of the positive electrode material layer is the thickness inside the secondary battery, and the average value of measurements taken at any 10 locations may be used.

[0025] The negative electrode active material may be a substance that facilitates the intercalation and deintercalation of lithium ions. From this perspective, the negative electrode active material may be, for example, various carbon materials, oxides, and / or lithium alloys.

[0026] Examples of 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 oxides for the negative electrode active material include at least one selected from the group consisting of silicon oxide, tin oxide, indium oxide, zinc oxide, and lithium oxide. The lithium alloy for the negative electrode active material can be any metal that can form an alloy with lithium, and may be a binary, ternary, or more-dimensional alloy of lithium with metals such as Al, Si, Pb, Sn, In, Bi, Ag, Ba, Ca, Hg, Pd, Pt, Te, Zn, and La.

[0027] The binder that may be included 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 resins, and polyamide-imide resins can be included. The conductive additive that may be included in the negative electrode material layer is not particularly limited, but at least one selected from the group consisting of carbon black such as thermal black, furnace black, channel black, Ketjen black, and acetylene black, graphite, carbon fibers such as carbon nanotubes and vapor-grown carbon fibers, metal powders such as copper, nickel, aluminum, and silver, and polyphenylene derivatives can be included. The negative electrode material layer may also contain components resulting from the thickening agent used during battery manufacturing (e.g., carboxymethylcellulose).

[0028] The thickness of the negative electrode material layer is not particularly limited, but may be between 1 μm and 300 μm, for example, between 5 μm and 200 μm. The thickness of the negative electrode material layer is the thickness inside the secondary battery, and the average value of measurements taken at any 10 locations may be used.

[0029] The positive electrode current collector and the negative electrode current collector used in the positive and negative electrodes are components that help collect and supply electrons generated in the electrode active material due to the battery reaction. Such electrode current collectors may be sheet-shaped metal members. Furthermore, electrode current collectors may have a porous or perforated form. For example, the current collector may be metal foil, perforated metal, mesh, or expanded metal. The positive electrode current collector used in the positive electrode is preferably made of metal foil containing at least one selected from the group consisting of aluminum, stainless steel, and nickel, for example, aluminum foil. On the other hand, the negative electrode current collector used in the negative electrode is preferably made of metal foil containing at least one selected from the group consisting of copper, stainless steel, and nickel, for example, copper foil.

[0030] The thickness dimensions of the positive electrode current collector and the negative electrode current collector are not particularly limited, but may be between 1 μm and 100 μm, for example, between 10 μm and 70 μm. The thickness dimensions of the positive electrode current collector and the negative electrode current collector are the thickness inside the secondary battery, and the average value of measurements taken at any 10 locations may be used.

[0031] Separators used in positive and negative electrodes are components provided primarily for preventing short circuits caused by contact between the positive and negative electrodes and for maintaining electrolytes. In other words, a separator can be described as a component that allows ions to pass through while preventing electronic contact between the positive and negative electrodes. For example, a separator is a porous or microporous insulating material, and due to its small thickness, it has a film form. Although this is merely an example, a microporous film made of polyolefin may be used as a separator. In this regard, the microporous film used as a separator may contain only polyethylene (PE) or only polypropylene (PP) as the polyolefin, for example. Furthermore, the separator may be a laminate composed of a "microporous film made of PE" and a "microporous film made of PP". The surface of the separator may be covered with an inorganic particle coating layer and / or an adhesive layer, etc. The surface of the separator may have adhesive properties. In this 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.

[0032] The thickness of the separator is not particularly limited, but may be between 1 μm and 100 μm, for example, between 2 μm and 20 μm. The thickness of the separator is the thickness inside the secondary battery (especially the thickness between the positive and negative electrodes), and the average value of measurements taken at any 10 locations may be used.

[0033] 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 sealed in an outer casing together with an electrolyte. The electrolyte may be a "non-aqueous" electrolyte containing an organic electrolyte and an organic solvent, or it may be an "aqueous" electrolyte containing water. When the positive electrode and the negative electrode have layers capable of intercalating and deintercalating lithium ions, the secondary battery preferably contains a "non-aqueous" electrolyte. That is, it is preferable that the electrolyte is a non-aqueous electrolyte. Metal ions released from the electrodes (positive electrode and / or negative electrode) will be present in the electrolyte, and therefore the electrolyte can assist in the movement of metal ions in the battery reaction. The electrolyte may be in liquid or gel form.

[0034] Non-aqueous electrolytes are electrolytes that contain a solvent and a solute. The solvent may be an organic solvent. Specific organic solvents of non-aqueous electrolytes may contain at least a carbonate. Such carbonates may be cyclic carbonates and / or linear carbonates. While not particularly limited, examples of 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). Examples of linear carbonates include at least one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and dipropyl carbonate (DPC). While this is merely an example, a combination of cyclic carbonates and linear carbonates may be used as the non-aqueous electrolyte; for example, a mixture of ethylene carbonate and diethyl carbonate may be used. Furthermore, as a specific solute for the non-aqueous electrolyte, for example, lithium salts such as LiPF6 and / or LiBF4 may be used.

[0035] The outer casing of a secondary battery is a component that encloses an electrode assembly, which consists of laminated electrode layers including a positive electrode, a negative electrode, and a separator. As will be described later, the outer casing may be a metal casing with a non-laminate structure.

[0036] [Features of the secondary battery of the present invention] The secondary battery of the present invention is characterized in at least by an opening in the outer casing that encloses the electrode assembly. In particular, it is characterized by an electrode terminal provided so as to cover the opening in the outer casing and an associated battery opening mechanism.

[0037] In the secondary battery of the present invention, electrode terminals (positive or negative terminals) arranged on the casing using an insulating sealing member are electrically connected to the electrode assembly via a conductive member. The insulating sealing member is interposed between the electrode terminals and the casing and is provided around the opening in the casing through which the conductive member passes. The electrode terminals and the casing are bonded to each other by this insulating sealing member provided around the opening in the casing. It can be said that the electrode terminals are preferably bonded to the insulating sealing member, and the casing is also preferably bonded to the insulating sealing member. In other words, the casing is provided with an opening through which the conductive member passes, and the electrode terminals are provided on the surface of the casing (on the outer surface of the casing) corresponding to the area surrounding the opening, utilizing the adhesive force of the insulating sealing member so as to cover the opening. Preferably, the electrode terminals are provided on the casing solely by the adhesive force of the insulating sealing member, without relying on mechanical or structural actions such as crimping (simply put, the electrode terminals and / or the casing are preferably provided on the casing without being crimped).

[0038] In this invention, the electrode terminals related to the battery cleavage mechanism are unlike those seen in conventional designs. In particular, the contour of the electrode terminals in plan view has a unique shape that differs from conventional designs. Specifically, the contour of the electrode terminals in plan view is composed of both straight and curved portions.

[0039] More specifically, in the electrode terminals, the plan view contour of the electrode terminals on the surface in contact with the insulating seal member consists of both straight and curved portions. In the outer casing, the plan view contour of the outer casing on the surface in contact with the insulating seal member includes a curve. In such a secondary battery of the present invention, the curved portion of the electrode terminals and a part of the curve of the outer casing face each other.

[0040] Figure 2 shows the external appearance of a secondary battery 1000 according to one embodiment of the present invention, and Figures 3(A) and 3(B) show the secondary battery 1000 according to one embodiment of the present invention in cross-sectional view and half-split perspective view. Furthermore, Figure 4 shows the elements related to the features of the secondary battery of the present invention separately in order to facilitate understanding of the present invention.

[0041] Figures 5(A) to 5(D) show a plan view of the top side (the side where the electrode terminals are installed) of a secondary battery, and in particular show the plan view contours of the electrode terminals and the casing. Figures 6(A) to 6(D) show the plan view contours of the electrode terminals corresponding to Figures 5(A) to 5(D), respectively. Figures 5(A) and 6(A) show the plan view contours corresponding to Figures 2 to 4, and Figures 5(B) to 5(D) and 6(B) to 6(D) show the plan view contours of secondary batteries according to other preferred embodiments.

[0042] As shown in Figures 5(A)-(D) and 6(A)-(D), the plan view contour 250 of the electrode terminal 200, viewed from the outside of the secondary battery, has a unique shape consisting of two types: a straight section 252 and a curved section 254. In other words, the plan view contour of the electrode terminal on the surface in contact with the insulating seal member consists of both a straight section and a curved section (hereinafter, the outer contour or outer edge contour of the electrode terminal on the surface in contact with the insulating seal member will also be referred to as the "plan view contour of the electrode terminal" or simply the "contour of the electrode terminal").

[0043] Furthermore, as shown in Figures 5(A) to (D), the plan view contour 160 of the casing 100, when viewed from the outside of the main surface of the secondary battery, is preferably curved. That is, the plan view contour 160 of the casing 100 on the surface that contacts the insulating sealing member 300 (particularly the outer edge contour forming the outer edge of the battery) includes curvature. For example, the plan view contour 160 of the casing 100 on the surface that is in direct contact with the insulating sealing member 300 used for installing the electrode terminals 200 includes curvature (hereinafter, the outer contour or outer edge contour of such a casing when viewed from the outside as a whole will also be referred to as the "plan view contour of the casing" or simply the "contour of the casing"). In one preferred embodiment, the plan view contour 160 of such casing 100 is curved as a whole, for example, the entire plan view contour of the casing is curved. The plan view contour 160 of the casing 100 may be circular, for example.

[0044] In the secondary battery of the present invention, in a plan view, the curvature of the outline of the casing faces the curved portion of the electrode terminal, preferably directly facing it. That is, as shown in Figures 5(A) to (D), for example, the curved portion 254 of the plan view outline 250 of the electrode terminal 200 and a part 160a of the curve in the plan view outline 160 of the casing 100 face each other (preferably directly facing each other). In a plan view when the secondary battery is viewed from the outside, it can also be said that the curved portion of the outline of the electrode terminal 200 and a part of the curve in the outline of the casing 100 face each other or are facing each other. In this specification, "face each other" means that in the plan view outline of the secondary battery, the curved portion of the electrode terminal and the curve of the casing are adjacent to or aligned with each other (for example, in a plan view of the battery when the secondary battery is viewed from the outside, they are adjacent to or aligned with each other while being separated from each other), and preferably they are adjacent to or aligned with each other more proximal or more directly.

[0045] In the secondary battery of the present invention, the electrode terminals correspond to output terminals for external connection. In particular, the electrode terminals are provided on the main surface of the outer casing so as to cover an opening provided therein, and preferably the electrode terminals are bonded or attached via an insulating sealing member provided around the opening. The electrode terminal 200 has, for example, a flat plate shape (see Figures 3 and 4). In other words, the electrode terminal 200 may be a flat plate-shaped member (for example, an electrode terminal 200 in which the main surfaces facing each other are planar). The flat plate-shaped electrode terminal may be, for example, a metal disc. Because it is flat, the thickness of the electrode terminal may be substantially constant.

[0046] The electrode terminals are electrically connected to the conductive member of the electrode assembly. The conductive member may be a member containing metal (for example, simply put, a metal member), and preferably a metal member having an elongated shape. For example, the conductive member may consist of the electrode current collector of the electrode assembly, or it may be a current collector lead provided on the electrode assembly (especially its electrodes). If the conductive member consists of the electrode current collector, the conductive member may consist of the metal portion of the electrode current collector that does not have electrode material. If the conductive member consists of a current collector lead, the conductive member may consist of a metal member having a thin-walled form and / or an elongated form. In the present invention, the conductive member that electrically connects the electrode assembly and the electrode terminals to each other may also be called a "tab". The conductive member is preferably flexible and may be provided in a bent and / or curved form to contribute to the detachment mechanism described later.

[0047] In the present invention, only one electrode terminal may be provided for a battery. That is, as shown in Figures 2 and 3, a single electrode terminal 200 may be provided for a single main surface of a battery. In the case of a single electrode terminal, the closed region formed by the plan view contour 250 of the electrode terminal may also be single, as shown in Figures 6(A) to (D), for example. That is, as shown in the plan view of Figures 6(A) to (D), a single closed region of the plan view contour 250 of the electrode terminal is formed inside the closed region formed by the plan view contour of the casing (in particular, the plan view contour 160 of the casing that forms the outer edge of the casing). The material of the electrode terminal 200 is not particularly limited as long as it is electrically conductive. The electrode terminal may be made of a metal material that is commonly used as a terminal material for secondary batteries. For example, the electrode terminal may be made of at least one metal selected from the group consisting of iron, SUS, aluminum, nickel, and copper.

[0048] In this specification, "planar view contour of electrode terminal" refers to the contour of the electrode terminal when viewed in plan view (for example, the contour of the terminal shape obtained when the electrode terminal is viewed along the normal or perpendicular direction of the main surface of the electrode terminal). Preferably, the outer edge contour of the surface constituting the electrode terminal that is in direct contact with the insulating sealing member used for installing the electrode terminal (for example, the electrode terminal surface that is in the same plane as the contacting surface) may be considered as the "planar view contour of electrode terminal". In short, the "planar view contour of electrode terminal" can correspond to the contour shape formed by the outer edge (preferably the outermost edge) of the electrode terminal. Similarly, "planar view contour of casing" refers to the contour of the casing when viewed in plan view, as described above, and typically refers to the outer edge contour or outer contour of the casing. Preferably, the "planar view contour of the exterior" may refer to the contour, outer contour, or outer edge contour (preferably a contour that can be located outside the contour of the electrode terminal when viewed in plan view, or an outer contour or outer edge contour) of the surface constituting the exterior body that is in direct contact with the insulating sealing member used for installing the electrode terminals (for example, the exterior body surface that is on the same plane as the contact surface). In one preferred embodiment, the "planar view contour of the exterior" in the present invention may be considered to be the contour formed by the exterior when the secondary battery is viewed from a direction perpendicular to the main surface of the electrode terminals (for example, the contour of the exterior body that is located outside the electrode terminals, or the outer contour or outermost contour of the exterior body).

[0049] As described above, the present invention features an electrode terminal whose plan view contour consists of both a straight portion and a curved portion. With such a configuration, areas other than the electrode terminal on one main surface of the battery are more easily provided as suitable areas. In the embodiments shown in Figures 6(A) to (D), both the terminal area 110A and the non-terminal area 110B can be more suitably provided on the main surface of the battery where the electrode terminal is located. In particular, with an electrode terminal contour consisting of a straight portion and a curved portion, the proportion of the plan view area of ​​the non-terminal area 110B on the main surface of the battery can be suitably or more significantly secured compared to the case where such an electrode terminal contour configuration is not present. Therefore, the non-terminal area 110B provided together with the terminal area 110A on the main surface of the battery increases the design freedom of the battery. For example, it becomes easier to provide external lead members for external connection to the non-terminal area 110B, making the secondary battery of the present invention more suitable (for example, it may be possible to design a compact battery by providing circuits that are provided outside the battery on the main surface of the secondary battery of this application). These issues tend to become apparent when the plan view contour of the outer casing at the surface in contact with the insulating sealing member includes curvature, and when the curved portion of the electrode terminal and a part of the curvature of the outer casing face each other.

[0050] Furthermore, by having the plan view contour of the electrode terminal composed of both straight and curved portions, it becomes easier to suitably provide both the terminal region and the non-terminal region on the main surface of the battery, while also making it easier to suitably secure the sealing area associated with the electrode terminal. In other words, it becomes easier to suitably secure the proportion of the plan view area of ​​the non-terminal region 110B on the main surface of the battery without unfavorably impairing the sealing strength and / or long lifespan. To put it another way, by having the plan view contour of the electrode terminal composed of both straight and curved portions, it becomes easier to suitably provide the terminal region and the non-terminal region on the main surface of the battery while suitably securing the area of ​​the sealing region associated with the electrode terminal via the insulating sealing member on the outer casing (hereinafter also referred to as the "seal area"). This is also more apparent when the plan view contour of the outer casing on the surface in contact with the insulating sealing member includes a curve, and the curved portion of the electrode terminal and a part of the curve of the outer casing face each other.

[0051] The planar contour of the electrode terminal, which is composed of both straight and curved sections, contributes favorably to a safety mechanism when the internal cell pressure rises, i.e., a battery rupture mechanism. When the internal cell pressure rises abnormally, the electrode terminal ruptures outward to prevent an unintended battery explosion, but in the secondary battery of the present invention, this rupture is relatively more likely to occur from the "straight section". In other words, the electrode terminal is more likely to rupture from the straight portion of the planar contour of the electrode terminal (such rupture will be described later), and the predictability of abnormal increases in internal cell pressure is increased. In other words, the secondary battery of the present invention can be provided as a safer battery while avoiding as much unpredictability as possible regarding the rupture mode when the internal cell pressure rises excessively. This effect is more likely to become apparent when the planar contour of the outer casing at the surface in contact with the insulating seal member includes curvature, and when the curved portion of the electrode terminal and a part of the curvature of the outer casing face each other.

[0052] In the secondary battery of the present invention, the curved portion of the electrode terminal faces the curve of the outer casing. In a preferred embodiment, the straight portion of the electrode terminal also faces the curve of the outer casing (a curved portion different from the portion facing the curved portion of the electrode terminal). This will be explained more specifically with reference to Figures 5(A) to (D). As described above, in the secondary battery of the present invention, the curved portion 254 in the plan view contour 250 of the electrode terminal 200 and a part 160a of the curve in the plan view contour 160 of the outer casing 100 face each other. Such a facing relationship between the electrode terminal and the outer casing may also be formed with respect to the straight portion of the electrode terminal. The curve in the plan view contour 160 of the outer casing 100 may have a portion facing the curved portion 254 of the plan view contour 250 of the electrode terminal 200, as well as a portion facing the straight portion 252. In the plan view shown in Figures 5(A) to (D), the plan view contour 160 of the outer casing 100 is curved as a whole, and a curved portion 160b of the outer casing, which is different from "a part 160a of the curvature of the outer casing 100 that the curved portion 254 of the electrode terminal 200 faces," faces the straight portion 252 of the electrode terminal 200. In this embodiment, the effects of making it easier to provide the external lead member and / or making it easier to provide a suitable detachment mechanism become more apparent.

[0053] In the secondary battery of the present invention, the curved portion of the electrode terminal and the curve of the casing face each other, but it is preferable that the curved portion of the electrode terminal in plan view is positioned proximal to the outer contour of the casing in plan view than other parts of the electrode terminal (non-curved contour portions). It is preferable that the curved portion of the electrode terminal's contour in plan view is positioned relatively proximal to the curve of the contour of the casing in plan view than the straight portion of the contour. For example, in the plan view shown in Figures 5(A) to (D), the separation distance between the curved portion 254 of the electrode terminal 200 and a part 160a of the curve of the casing 100 facing it (the "minimum separation distance" described below) may be smaller than the separation distance between the straight portion 252 of the electrode terminal 200 and another part 160b of the curve of the casing 100 facing it (a curved portion 160b different from the part 160a) (the "minimum separation distance"). This will be further explained using Figures 6(A) to (D). In the plan views of Figures 6(A) to (D), when comparing the "shortest separation distance Lw between the curved portion 254 of the plan view contour 250 of the electrode terminal 200 and the plan view outer contour 160 of the casing 100" and the "shortest separation distance Ls between the straight portion 252 of the plan view contour 250 of the electrode terminal 200 and the plan view outer contour 160 of the casing 100," Lw is smaller than Ls. It can be said that the straight portion of the plan view contour of the electrode terminal is positioned relatively distal to the plan view outer contour of the casing compared to the curved portion. In the case of an electrode terminal having such a plan view contour, the terminal region and non-terminal region can be more suitably provided on the main surface of the battery, making it easier to produce the desired secondary battery. For example, it becomes easier to provide an external lead member for external connection to the non-terminal region. Preferably, it becomes easier to suitably secure the terminal region and non-terminal region on the main surface of the battery while suitably securing the sealing area. The "minimum separation distance Lw" mentioned above refers to the minimum or shortest distance in the direction perpendicular to the tangent to the curved section in a plan view. Similarly, the "minimum separation distance Ls" mentioned above refers to the minimum or shortest distance in the direction perpendicular to the straight section.

[0054] In one preferred embodiment, one end of the straight portion and one end of the curved portion are shared with each other so that the straight portion and the curved portion are continuous in the plan view contour of the electrode terminal (for example, so that they form a continuous plan view contour). In other words, the plan view contour of the electrode terminal is constructed such that the straight portion and the curved portion are connected via their ends. In the plan view contours of the electrode terminals in Figures 7(A) to (D), which correspond to Figures 6(A) to (D), one end 252a of the straight portion 252 and one end 254a of the curved portion 254 may overlap so as to be shared with each other, thereby constructing the plan view contour 250 so that the straight portion 252 and the curved portion 254 are connected to each other. With an electrode terminal having such a plan view contour, it becomes easier to more favorably secure the terminal region and the non-terminal region on the main surface of the battery, making it easier to produce the desired secondary battery. For example, it becomes easier to provide an external lead member for external connection in the non-terminal region. Preferably, while ensuring a suitable sealing area, the terminal region and the non-terminal region on the main surface of the battery are more easily provided.

[0055] In the plan view contour of the electrode terminal, the curved portion may be arc-shaped. In other words, the plan view contour of the electrode terminal may include a shape corresponding to a part of a circle. In the embodiments shown in Figures 7(A) to (D), the plan view contour 250 of the electrode terminal may be composed of an arc-shaped contour 254' as the curved portion 254 and a straight portion 252 combined with it. In the case of a plan view contour of an electrode terminal including such an arc-shaped curved portion, it becomes easier to more favorably secure the terminal area and the non-terminal area on the main surface of the battery, preferably while favorably securing the sealing area, making it easier to obtain the desired secondary battery. This is more evident when the secondary battery is button-type or coin-type. For example, it becomes easier to favorably provide an external lead member for external connection to the non-terminal area, contributing to a more favorable battery design. This is merely an example, but the plan view contour of the electrode terminal may include an arc-shaped curved portion corresponding to at least a semicircle, quarter circle, sixth circle, or eighth circle circumference.

[0056] When the curved portion has an arc shape and the plan view contour of the casing (particularly the plan view outer contour of the casing that forms the outer edge of the casing) has a circular shape, the virtual circle constituting the arc of the curved portion and the circle of the plan view contour of the casing may be concentric with each other. In other words, in plan view, the arc contour of the electrode terminal and the circular contour of the casing may share the same center of circle. This makes it easier to secure a more uniform and larger sealing area between the electrode terminal and the casing, and consequently, the bonding strength and long-term reliability of the sealing related to the electrode terminal (simply put, the bonding of the electrode terminal in the area surrounding the opening of the casing) can be more favorably ensured. Note that "concentric circles" in this specification is not necessarily limited to a perfectly concentric relationship, but also includes substantially concentric forms that can be considered to have a substantially concentric relationship in the perception of a person skilled in the art, even if they are modified from a perfectly concentric relationship (for example, the center of the circle may be shifted by a distance of, for example, within 30%, 20%, 10%, 5%, or 3% of the diameter of the circular plan view contour of the casing).

[0057] In one preferred embodiment, the proportion of the curved portion in the plan view contour of the electrode terminal is relatively larger than the proportion of the straight portion. That is, in the plan view contour of the electrode terminal, the total length of the curved portion may be relatively longer than the total length of the straight portion. In the embodiment shown in Figure 8, the length of the straight portion 252 is L a The length of the curved section 254 is set to L b Therefore, L a <L b This may be the case. In the case of a plan view contour of an electrode terminal where the proportion of the curved portion is larger than the proportion of the straight portion, the terminal region and the non-terminal region can be more favorably secured on the main surface of the battery, making it easier to obtain the desired battery. For example, it becomes easier to provide an external lead member for external connection in the non-terminal region. Preferably, the terminal region and the non-terminal region can be favorably provided on the main surface of the battery while favorably securing the sealing area associated with the electrode terminal. This is merely an example, but the length L of the curved portion b The length of the straight section is L a It may be 1.2 times or more, for example, 1.5 times or more. The length L of such curved portion. b There is no particular upper limit, but the length L of the straight section is...a It may be three times, two times, etc. of [the original value]. Therefore, although it is merely an example, the planar outline of the electrode terminal is 1.2L a ≤ L b ≤ 3L a , 1.2L a ≤ L b ≤ 2.5L a , 1.2L a ≤ L b ≤ 2L a , 1.5L a ≤ L b ≤ 3L a , 1.5L a ≤ L b ≤ 2.5L a or 1.5L a ≤ L b ≤ 2L a and may have relative length relationships such as these.

[0058] In a certain preferred embodiment, the planar outline of the electrode terminal is composed only of straight portions and curved portions. For example, as shown in FIGS. 6(A) to (D), it is composed only of two types, a straight portion 252 and a curved portion 254. In short, the planar outline of the electrode terminal may be composed only of a combination of "straight lines" and "curves". In such a case, the features of the present disclosure are more prominent, and the effects of the present invention are more likely to be manifested. That is, it is easier to preferably secure a terminal region and a non-terminal region on the main surface of the battery. For example, it is easier to provide an external lead-out member for external connection to the non-terminal region. Preferably, while preferably securing the sealing area related to the electrode terminal, the effect that the terminal region and the non-terminal region are preferably provided in a well-balanced manner on the main surface of the battery can be more prominent.

[0059] In the secondary battery of the present invention, electrode terminals are provided on the outer casing. The electrode terminals may be provided on an area including at least a part of the main surface of the outer casing (preferably a part of a planar main surface). In particular, the electrode terminals are provided on the outer casing so as to cover at least an opening in the outer casing (also referred to herein as the "outer casing opening") through which a conductive member electrically connected to the electrode terminal (i.e., a conductive member extending from the electrode assembly) passes. Preferably, the electrode terminals are provided on the outer casing so as to cover the entire opening in the outer casing, and also preferably so as to extend to the planar outer casing surface around the opening in the outer casing. In this specification, "outer casing" means a member for housing or enclosing an electrode assembly in which electrode constituent layers including a positive electrode, a negative electrode, and a separator are laminated. For example, the outer casing may be a metal outer casing having a non-laminate structure. This means that the outer casing is not a laminated member consisting of a metal sheet / fusion layer / protective layer, etc. The exterior body in this invention may differ from the exterior body of a soft-case type battery, which corresponds to a pouch made of so-called laminate film. A metal exterior body having a non-laminated structure preferably has a structure made of a single metal component. For example, such a metal exterior body may be a single metal component made of iron, stainless steel (SUS), and / or aluminum. Here, "single metal component" broadly means that the exterior body does not have a so-called laminated structure, and narrowly means that the exterior body is a component made substantially only of metal. Therefore, if the component is made substantially only of metal, the surface of the metal exterior body may be subjected to an appropriate surface treatment. For example, in the cross-section obtained by cutting such a metal exterior body in the thickness direction, a single metal layer can be seen except for the parts that have been surface-treated. In this specification, "stainless steel" refers to stainless steel as defined in, for example, "JIS G 0203 Steel Terminology," and may be an alloy steel containing chromium or chromium and nickel. In one preferred embodiment, the exterior body may have a can shape (in which case, the exterior body can be said to have an "exterior can").

[0060] In the secondary battery of the present invention, the casing may be composed mainly of two parts. For example, the casing may be composed of two parts: a first metal casing and a second metal casing made of metal members. In the case of a casing with a non-laminate structure, each of the first metal casing and the second metal casing may be a single metal member. In the present invention, the casing may have a relatively thin thickness. For example, each of the first metal casing and the second metal casing may have a thickness 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.

[0061] In an exterior body composed of two parts, a first metal exterior body and a second metal exterior body, the aforementioned "exterior body opening" may be provided in either the first or second metal exterior body. In other words, an opening may be provided in either the first or second metal exterior body, and electrode terminals may be provided in the sub-exterior body having the opening. The first and second metal exterior bodies of the metal members may be combined to form an exterior body by laser welding, or they may be combined to form an exterior body by crimping.

[0062] One of the first and second metal casings may be a cup-shaped member, and the other of the first and second metal casings may be a lid-shaped member. In such a case, the metal casings may be joined together, for example, by welding or crimping the peripheral edge of the lid-shaped member from the outside, thereby enabling relatively simple sealing. A "cup-shaped member" means a member having a side wall or side portion corresponding to the body and a main surface portion continuous therewith (in a typical embodiment, for example, the bottom portion), with a hollow portion formed on the inside. A "lid-shaped member" means a member that is combined to cover the cup-shaped member (preferably a member that is in contact with the side wall of the cup-shaped member and is provided to block the inner hollow portion of the cup-shaped member from the outside). The lid-shaped member may be, for example, a single member (typically a flat plate-shaped member) that extends in the planar direction (particularly in a direction perpendicular to the direction in which the side wall of the cup-shaped member extends vertically), and may be a member that is in contact with the side wall of the cup-shaped member.

[0063] The aforementioned "exterior opening" may be provided on the lid-shaped member. That is, the exterior is composed of a cup-shaped member 100A and a lid-shaped member 100B, and the lid-shaped member 100B, rather than the cup-shaped member 100A, may have the exterior opening 150 (see Figure 4). When the lid-shaped member has the exterior opening, electrode terminals are provided on the lid-shaped member. In this case, the secondary battery can be manufactured by first obtaining a combination body with electrode terminals on the lid-shaped member, and the secondary battery can be obtained relatively easily.

[0064] Furthermore, the “exterior opening” may be provided on the cup-shaped member. In other words, the exterior is composed of a cup-shaped member and a lid-shaped member, and the cup-shaped member, rather than the lid-shaped member, may have the exterior opening (for example, the exterior opening may be provided on the surface corresponding to the bottom of the cup-shaped member). If the cup-shaped member has an exterior opening, electrode terminals may be provided on the cup-shaped member (for example, on the surface corresponding to the bottom of the cup-shaped member).

[0065] When the metal casing consists of a cup-shaped member and a lid-shaped member, the cup-shaped member and the lid-shaped member may be airtightly sealed by joining. In other words, the cup-shaped member and the lid-shaped member are not crimped together, and therefore, airtight sealing by crimping is not required. This makes it easier to create a secondary battery that is more space-saving than a secondary battery with a casing that is crimped. In short, the non-crimped form of the cup-shaped member and the lid-shaped member contributes favorably to miniaturization and improvement of energy density of the secondary battery.

[0066] In the present invention, the opening of the outer casing may also have a contour shape similar to that of the electrode terminals. That is, in a secondary battery having a conductive member that electrically connects the electrode assembly and the electrode terminals, and in a secondary battery in which an insulating sealing member is interposed between the electrode terminals and the surface of the outer casing around the opening of the outer casing through which the conductive member passes, the outer contour of the opening of the outer casing in plan view may consist of both a straight portion and a curved portion. Figures 9(A) to 9(D) show the plan view contours of the outer casing corresponding to Figures 5(A) to 9(D) or Figures 6(A) to 9(D), respectively. In the plan view of the outer casing 100 shown in Figures 9(A) to 9(D) (plan view excluding the electrode terminals), the contour 180 of the opening 150 of the outer casing is composed of two types: a straight portion 182 and a curved portion 184. That is, the shape of the opening edge forming the opening 150 of the outer casing is composed of a straight portion and a curved contour. In one preferred embodiment, the contour 180 of the exterior opening 150 is composed of only two types of portions: a straight portion 182 and a curved portion 184. Therefore, the shape of the opening edge forming the exterior opening 150 is composed only of a straight portion and a curved contour.

[0067] In secondary batteries with an outer casing opening having such a planar contour, a more suitable seal can be obtained. Specifically, the planar contour of the outer casing opening and the planar contour of the electrode terminals tend to be similar in shape to each other, and the sealing of the electrode terminals in the area surrounding the outer casing opening tends to be more uniform (preferably, the width dimension of the seal area formed around the outer casing opening tends to be constant along the opening). In other words, a battery that is safer in terms of stable hermetic sealing tends to be obtained.

[0068] In the case of the contour shapes 180 of the outer casing opening 150 shown in Figures 9(A) to (D), their shapes themselves are similar to the contour shapes 250 of the electrode terminals shown in Figures 6(A) to (D). Therefore, the various characteristics described above regarding the plan view contour 250 of the electrode terminals can similarly be applied to the plan view contour 180 of the outer casing opening 150.

[0069] In the secondary battery of the present invention, an insulating seal member is provided between the electrode terminals and the outer casing. Figure 10 shows a cross-sectional view of the relative arrangement of the outer casing 100, the electrode terminals 200, and the insulating seal member 300. As can be seen from the configuration shown in Figure 10, the insulating seal member 300 is interposed between the outer casing 100 and the electrode terminals 200. The outer casing 100 has an outer casing opening 150, and the insulating seal member 300 is arranged on the outer casing surface 158 around the outer casing opening 150. Preferably, in the region surrounding the outer casing opening 150, the electrode terminals 200 are joined to the outer casing 100 via the insulating seal member 300 due to the bonding properties of the insulating seal member 300. As shown in Figure 10, the electrode terminals 200 are preferably attached to the insulating seal member 300 so as to close the outer casing opening 150 from the outside. In one preferred embodiment of the present invention, an insulating sealing member 300 is interposed between the electrode terminals 200 and the surface 158 of the outer casing around the opening 150 through which the conductive member 400 passes. As can be seen from Figure 10, the insulating sealing member 300 is sandwiched between the electrode terminals 200 and the outer casing 100 in the junction region between the electrode terminals 200 and the outer casing 100.

[0070] The insulating seal member 300 may be provided on the surface of the outer casing (preferably on the outer surface of the outer casing) along the periphery of the opening 150. To provide better insulation, the insulating seal member 300 may be provided to extend beyond the electrode terminals 200. That is, for example as shown in Figure 10, the insulating seal member 300 may be provided on the outer casing 100 so as to protrude outward from the electrode terminals 200. Similarly, to provide better insulation, the insulating seal member 300 may be provided further inward beyond the edge of the opening 150 of the outer casing 100. That is, for example as shown in Figure 10, the insulating seal member 300 may extend further inward beyond the edge portion 155 that forms the opening 150 on the outer casing 100, and therefore a part of the insulating seal member 300 may extend into the area of ​​the opening 150.

[0071] In this specification, "insulating sealing member" refers to at least a member interposed between the outer casing and the electrode terminals, contributing to insulation between them, and also means a member that contributes to battery sealing (more specifically, hermetically sealing between the outer casing and the electrode terminals). There are no particular restrictions on the material type of the insulating sealing member as long as it exhibits insulating properties. "Insulation" as used in this specification may mean having the insulating properties of a general insulator and therefore the electrical resistivity of a general insulator, and is merely an example, but at least 1.0 × 10⁻⁶ 5 Ω·m or greater, preferably 1.0 × 10⁻⁶ 6 Ω·m or greater, more preferably 1.0 × 10 7It may have a resistivity of Ω·m or more (at room temperature of 20°C). Preferably, the insulating seal member has not only insulating properties but also fusion properties, as this makes it easier to improve the sealing performance. For example, the insulating seal member may be made of a thermoplastic resin. This is merely one specific example, but the insulating seal member may be made of polyethylene and / or polyolefin such as polypropylene. From another perspective, since the insulating seal member as an insulating bonding material can easily be expected to improve the sealing performance, it may also contain components of an adhesive that exhibits insulating properties. Examples of such adhesives (i.e., materials for insulating sealing members) include acrylic adhesives such as acrylic acid ester copolymers, rubber adhesives such as natural rubber, silicone adhesives such as silicone rubber, urethane adhesives such as urethane resin, α-olefin adhesives, ether adhesives, ethylene-vinyl acetate resin adhesives, epoxy resin adhesives, vinyl chloride resin adhesives, chloroprene rubber adhesives, cyanoacrylate adhesives, aqueous polymer-isocyanate adhesives, styrene-butadiene rubber adhesives, nitrile rubber adhesives, nitrocellulose adhesives, reactive hot-melt adhesives, phenolic resin adhesives, modified silicone adhesives, polyamide resin adhesives, polyimide adhesives, polyurethane resin adhesives, polyolefin resin adhesives, polyvinyl acetate resin adhesives, polystyrene resin solvent adhesives, polyvinyl alcohol adhesives, polyvinylpyrrolidone resin adhesives, polyvinyl butyral resin adhesives, polybenzimidazole adhesives, polymethacrylate resin adhesives, melamine resin adhesives, urea resin adhesives, and / or resorcinol adhesives.

[0072] Secondary batteries in which an insulating sealing member is interposed between the electrode terminals and the surface of the outer casing are more likely to be supplied as safer batteries. In other words, if an abnormal situation occurs in which the internal pressure of the outer casing rises, a crack (preferably a crack that opens so that the electrode terminals move toward the outside of the battery) can be brought about in order to prevent more serious accidents such as unintended battery explosions. In other words, in order to prevent the rupture phenomenon in which the battery explodes due to an increase in the internal pressure of the outer casing (referred to herein as "cell pressure") caused by gas generated by abnormal heat generation inside the battery due to overcharging or internal short circuit, it is preferable that the secondary battery is equipped with a vent mechanism that releases internal gas when such cell pressure rises excessively. In this regard, the secondary battery of the present invention is preferably able to displace so that the sealed state in which the electrode terminals are blocking the opening of the outer casing is released when the cell pressure rises excessively. In other words, when the internal pressure of the cell rises abnormally, the electrode terminals are displaced to open up, peeling away from the insulating sealing material on the surface of the outer casing (see Figure 11). This allows the opening in the outer casing to communicate with the outside, enabling the internal gas to escape and preventing battery explosions.

[0073] In the present invention, the insulating seal member may also have a contour shape similar to that of the electrode terminal. That is, the plan view contour of the insulating seal member may consist of both straight and curved portions. Figures 12(A) to 12(D) show the plan view contours of the insulating seal member 300 corresponding to Figures 5(A) to 12(D) or 6(A) to 12(D), respectively. As shown in Figures 12(A) to 12(D), the outer contour 350 of the insulating seal member 300 consists of two types: a straight portion 352 and a curved portion 354. That is, the plan view contour of the outer edge of the insulating seal member 300 consists of a straight contour and a curved contour. In one preferred embodiment, the outer contour of the insulating seal member 300 consists of only two types: a straight portion and a curved portion, and therefore the plan view contour of the outer edge of the insulating seal member 300 consists only of a straight contour and a curved contour. The inner contour of the insulating seal member 300 may be similar. The inner contour 360 of the insulating seal member 300 is composed of two types: a straight portion 362 and a curved portion 364. In other words, the plan view contour of the inner edge of the insulating seal member 300 is composed of a straight contour and a curved contour. In one preferred embodiment, the inner contour of the insulating seal member 300 is composed of only two types: a straight portion and a curved portion, and therefore the plan view contour of the inner edge of the insulating seal member 300 is composed of only a straight contour and a curved contour.

[0074] In a secondary battery equipped with an insulating seal member 300 having such a planar contour, a more suitable seal is more easily achieved. Specifically, the planar contours of the outer and / or inner edges of the insulating seal member and the planar contours of the electrode terminals tend to be similar in shape to each other, thereby allowing the insulating seal member, together with the electrode terminals, to contribute to a more uniform seal in the area surrounding the opening of the outer casing (preferably, the width dimension of the seal area formed around the opening of the outer casing tends to be constant along the periphery of the opening). In other words, a battery that is safer in terms of stable hermetically sealed is more easily achieved.

[0075] The contour shapes of the insulating seal members 300 shown in Figures 12(A) to (D) are similar in shape to the contour shapes 250 of the electrode terminals shown in Figures 6(A) to (D). Therefore, the various characteristics described above regarding the plan view contour 250 of the electrode terminals can similarly apply to the plan view contours 350 and 360 of the insulating seal members.

[0076] In one preferred embodiment, the separation distance between the curved portion 254 of the plan view contour 250 of the electrode terminal 200 and the plan view outer contour 160 of the casing 100 is constant. This is especially true when the curved portion 250 of the electrode terminal 200 has an arc shape, and the plan view contour of the casing (particularly the plan view outer contour of the casing forming the outer edge of the casing) has a circular shape (see Figures 6(A) to (D)). In other words, the "minimum separation distance Lw" explained using Figures 6(A) to (D) may be a constant distance in plan view. Such a constant separation distance contributes to a more uniform seal. That is, the width dimension of the seal area formed around the opening of the casing tends to be constant along the perimeter of the opening, making it easier to achieve a more stable hermetic seal.

[0077] In one preferred embodiment, the electrode terminals in the present invention are non-crimped metal plates. Furthermore, because they are non-crimped metal plates, for example, in cross-sectional view, the metal plates extend on the same plane. In short, the electrode terminals that serve as external output terminals do not have a bent shape as a whole, but have a flat plate shape. For example, as shown in Figures 3(A) and 10, the cross-sectional shape of the electrode terminal 200 may be rectangular. Such electrode terminals 200 have not undergone a history of pressure deformation, and are more likely to provide longer-term stability from a material standpoint. In other words, they are more likely to be external output terminals suitable for long-term use of secondary batteries. Because of this non-crimped configuration, for example, in cross-sectional view, the insulating seal member 300 may also extend on the same plane. That is, the cross-sectional shape of the insulating seal member provided adjacent to the electrode terminal is not a bent shape, but may be rectangular, for example. As shown in Figures 3(A) and 10, the thickness of the insulating seal member 300 may be substantially constant. Such an insulating seal member 300 can be described as an insulating member or insulating material in which the effect of pressure deformation during the installation of electrode terminals is further reduced. The insulating seal member 300 may have a film form. For example, the insulating seal member 300 may be provided using a precursor of a film-like insulating member having a form close to the final shape.

[0078] Here, we will elaborate on the venting mechanism, or release mechanism, associated with the electrode terminals. As the internal pressure of the cell increases with battery use, such as charging and discharging, the force acting on the electrode terminals 200 due to the internal pressure also increases. In one preferred embodiment, when the internal pressure of the cell becomes excessively high, the force acting on the electrode terminals 200 exceeds the bonding force between the electrode terminals 200 and the casing 100 (i.e., the adhesive or fixing force of the electrode terminals 200 to the casing 100 via the insulating sealing member 300), allowing at least a portion of the electrode terminals 200 to detach from the casing 100. For example, the electrode terminals 200 are provided so as to cover an opening 150 in the casing 100, but the electrode terminals 200 can be displaced so as to open the cover (see Figure 11). This displacement of the electrode terminals 200 allows excess gas inside the casing to be released to the outside, preventing more serious accidents such as unintended battery explosions.

[0079] In this specification, "cell pressure" broadly refers to the pressure inside the casing of a secondary battery. In a narrower sense, "cell pressure" refers to the pressure inside the casing, which is equipped with an electrode assembly and is hermetically sealed (especially the internal pressure when the battery is in use). The "insulating seal member" in this embodiment contributes to the venting mechanism as described above and can be described as an insulating seal that can be peeled off in the event of an abnormality in the cell pressure, i.e., a peelable member.

[0080] The secondary battery of the present invention has an electrode terminal whose plan view contour consists of both a straight portion and a curved portion, which allows it to be used as a battery with a high degree of predictability when the internal cell pressure rises abnormally. Specifically, when the internal cell pressure rises abnormally, the electrode terminal is more likely to rupture starting from the portion corresponding to the "straight portion" of the plan view contour of the electrode terminal, thus increasing predictability and enabling a more suitable battery design.

[0081] When the internal pressure of a secondary battery cell increases, stress is exerted on the casing due to the internal pressure. In particular, when the internal pressure of the cell rises abnormally, deformation stress can act on the casing, causing it to bend or strain (see Figure 13). Such deformation stress tends to act in such a way that the bending is greater in the central region of the casing. In particular, the main surface of the casing, which extends substantially in a planar manner, is structurally more prone to bending than the sides of the casing, which may be provided as curved or bent surfaces. Therefore, when bending occurs due to an abnormal rise in internal pressure of the cell, the central point in the width direction of the main surface of the battery tends to have a greater curvature or bend than the outer parts, and the main surface of the casing (in the illustrated embodiment, its lid-like member 100B) may deform as shown in Figure 13, for example. Regarding such deformation of the casing (i.e., deformation of the battery), the area corresponding to the "straight part" of the planar contour of the electrode terminals is preferably located at or near the area with a relatively large curvature (hereinafter also referred to as the "maximum curvature area"). It can also be said that the straight portion 252 of the plan view contour of the electrode terminal 200 is positioned relatively proximal to the point of maximum curvature U than the curved portion 254 (see Figure 13). Therefore, the straight portion of the plan view contour of the electrode terminal is more susceptible to the deformation stress of the outer casing than the curved portion, and is more likely to cause cracking that causes the electrode terminal to peel off from the straight portion of the plan view contour of the electrode terminal. Such effects tend to become apparent in the following cases: "the curved portion of the electrode terminal and the curve of the outer casing are opposite to each other," "the straight portion of the electrode terminal is also opposite to the curve of the outer casing (a different curved contour portion than the portion opposite to the curved portion of the electrode terminal)," "the curved portion is positioned relatively proximal to the plan view outer contour than the straight portion," and / or "the proportion of the curved portion in the plan view contour is relatively larger than the proportion of the straight portion (i.e., the proportion of the straight portion in the plan view contour is relatively smaller than the proportion of the curved portion)."

[0082] In this way, when rupture occurs due to an abnormal increase in internal cell pressure, the electrode terminals are displaced to open from a point corresponding to the straight portion of the planar contour of the electrode terminals. Therefore, the secondary battery of the present invention allows for a more suitable battery design that takes such rupture into account. In other words, such a secondary battery is more likely to be a battery in which unpredictability regarding the rupture mode involving the outer casing is avoided as much as possible, and can be provided as a safer battery.

[0083] [Method for manufacturing a secondary battery according to 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 stacked, in an outer casing.

[0084] The electrode assembly can be manufactured using conventional methods, and a secondary battery can be obtained by placing it inside an outer casing. The outer casing is provided with an insulating seal member as a sealing material in the area surrounding the opening of the outer casing, and electrode terminals are provided via the insulating seal member so as to close the opening of the outer casing. For example, if the outer casing is composed of the aforementioned cup-shaped member and a lid-shaped member with a circular shape in plan view, a secondary battery can be obtained by the steps of: placing the electrode assembly inside the cup-shaped member and closing the opening end of the cup-shaped member with the lid-shaped member (for example, the lid-shaped member and the cup-shaped member may be joined together by welding or the like); and providing an insulating seal member in the area surrounding the opening of the outer casing, and providing electrode terminals to the outer casing via the insulating seal member so as to close the opening of the outer casing.

[0085] The electrode terminal itself, whose planar contour consists of both straight and curved sections, can be obtained by conventional metalworking methods. There are no particular restrictions on the type of metalworking method. For example, electrode terminals can be obtained through machining (e.g., cutting and / or grinding), plastic deformation (e.g., pressing and / or forging), and / or casting (sand casting and / or Geycasting). Alternatively, electrode terminals may be manufactured using a metal 3D printer.

[0086] The present invention can be embodied in various forms, which will be described below.

[0087] (Aspects relating to a single straight section and a curved section) This embodiment is characterized by the number of contour components in the plan view contour of the electrode terminal. Specifically, the plan view contour of the electrode terminal is composed of a single straight section and a single curved section. In other words, in the plan view contour of the electrode terminal, each of the two types of contour components is provided as a single element.

[0088] For example, in the plan view contour 250 of the electrode terminal 200 shown in Figure 8, only one straight portion 252 and only one curved portion 254 are provided. In this embodiment, it is preferable that in the plan view contour 250 of the electrode terminal 200, one end portion 252a of the straight portion 252 and one end portion 254a of the curved portion 254 are shared with each other, and the other end portion 252b of the straight portion 252 and the other end portion 254b of the curved portion 254 are shared with each other, so that the straight portion 252 and the curved portion 254 are continuous.

[0089] In this embodiment, in the plan view contour, the central point of the straight section and the central point of the curved section may face each other so as to straddle the battery center. In the plan view shown in Figure 8, the central point 252c that divides the straight section 252 in half and the central point 254c that divides the curved section 254 in half face each other with the battery center M in between. The plan view contour 250 may be configured such that a closed region is formed by a single curved section 254 and a single straight section 252 surrounding the battery center M. Here, "battery center M" broadly refers to the center of the main surface of the secondary battery, and narrowly refers to the center of the shape of the plan view outer contour of the casing (for example, if the shape of the plan view outer contour of the casing is circular, the center of that circle corresponds to "battery center M").

[0090] When the planar contour of the electrode terminal is composed of a single straight section and a single curved section, it becomes easier to suitably secure the terminal area and the non-terminal area on the main surface of the battery, making it easier to obtain the desired battery. For example, it becomes easier to provide an external lead member for external connection (i.e., a member provided separately from the electrode terminal for external output) in the non-terminal area, contributing to a more suitable battery design. Preferably, both the terminal area and the non-terminal area are suitably secured on the main surface of the battery while suitably securing the sealing area.

[0091] Regarding the exemplary embodiment shown in Figure 8, the plan view contour of the electrode terminal may have an "arch shape," a "D shape," and / or a "half-moon shape." In particular, the arch shape, D shape, and / or half-moon shape electrode terminals may be provided on the main surface of the battery so as to extend to the "battery center M" mentioned above. Furthermore, as can be seen from the exemplary embodiment shown in Figure 8, in the secondary battery of this disclosure, the electrode terminals, which include both a plan view straight contour and a plan view curved contour, may extend from the battery center toward one side of the battery. In other words, by making the contour of the electrode terminal a contour that includes both a plan view straight contour and a plan view curved contour, it becomes easier to secure a desired large sealing area while moving the electrode terminal toward one side from the center, and it becomes easier to secure a desired large exposed area of ​​the casing (especially the area of ​​the non-terminal region on the main surface of the casing on which the electrode terminals are provided) without impairing sealing strength and / or long lifespan.

[0092] (Installation method of external lead-out member) This embodiment relates to a battery configuration that facilitates a more favorable connection with the outside. Specifically, both an external lead member and another external lead member for external connection are provided on the same main surface of the battery. Here, the same main surface of the battery may correspond to the battery surface composed of electrode terminals and an outer casing. In other words, on the main surface of the battery on which the electrode terminals are provided (hereinafter also referred to as the "terminal-installed battery surface"), both an external lead member and another external lead member are provided on the main surface of the battery.

[0093] Figures 14(A) and 14(B) show an embodiment in which a pair of external lead members 500A and 500B are provided on a terminal-mounted battery surface 600 that includes a terminal area 110A and a non-terminal area 110B. As shown in Figure 14(B), a positive-side external lead member 500A for connection to an external circuit and / or external equipment, and a negative-side external lead member 500B for connection to an external circuit and / or external equipment are provided on the terminal-mounted battery surface 600. This configuration of a secondary battery is due to the plan view contour of the electrode terminals, which are composed of both straight and curved portions. In other words, because the plan view contour of the electrode terminals is composed of both straight and curved portions, the terminal area 110A and the non-terminal area 110B are more readily available on the terminal-mounted battery surface. Such a planar contour allows the non-terminal region 110B to be a larger area (particularly larger than the case where the planar contour of the electrode terminal has both straight and curved portions), making it easier to provide external lead members for external connection. Therefore, preferably, both one external lead member and the other external lead member can be suitably provided on the terminal-mounted battery surface. A secondary battery according to this embodiment has external lead members suitably concentrated on one main battery surface, making it a more suitable battery in terms of external connection.

[0094] Two external lead members provided on the terminal-mounted battery surface may be provided one on the electrode terminal and the other on the non-terminal area. In other words, one external lead member may be provided on the electrode terminal, and the other external lead member may be provided on the non-terminal area, which is the area of ​​the main battery surface other than the electrode terminal. This allows for more effective utilization of the terminal-mounted battery surface while maintaining the conductive function of the two external lead parts as desired. As shown in Figure 14(B), one and the other external lead members may be provided side by side on the main battery surface (preferably side by side adjacent to each other). This is merely an example, but at least a part of the positive electrode side external lead member may be placed on the electrode terminal so as to be electrically connected to the electrode terminal, and at least a part of the negative electrode side external lead member may be placed on the non-terminal area so as to be electrically connected to the non-terminal area. Alternatively, in the opposite configuration, at least a portion of the negative electrode external lead member may be positioned on the electrode terminal so as to be electrically connected to the electrode terminal, and at least a portion of the positive electrode external lead member may be positioned on the non-terminal region so as to be electrically connected to the non-terminal region.

[0095] The pair of external lead members 500A and 500B may be identical in form or shape. Alternatively, the pair of external lead members 500A and 500B may be different in form or shape. For example, as shown in Figure 14(B), the external lead members 500A and 500B may each have an elongated shape. The material of the external lead members is not particularly limited as long as they are electrically conductive. For example, the material of the external lead members 500A and 500B may be a metal commonly used for electrical connections of batteries. For example, the external lead members 500A and 500B may each be made up of at least one metal selected from the group consisting of iron, stainless steel, aluminum, nickel, and copper. In this disclosure, the external lead member is a member used to suitably connect the battery to the outside (for example, external circuits and / or external devices, or other elements that require the energy of the battery in this disclosure), and therefore may also be referred to as an "external output tab" or "conductive member for external connection." Thus, in the secondary battery of this disclosure, an external lead member, such as an external output tab, can be suitably attached to the same surface, thereby enabling a compact battery design that includes the external circuit.

[0096] For example, the secondary battery of this disclosure may have an external circuit above the terminal mounting surface, and the external circuit and the terminal mounting surface may be electrically connected by two external lead members provided on the terminal mounting surface. Preferably, both the one and the other external lead members are positioned between the terminal mounting surface and the external circuit. The external circuit, which is suitably positioned above the terminal mounting surface, is at least due to the positive electrode side and the negative electrode side external lead members provided on the same main battery surface (the main surface on the upper end side), and contributes to the realization of a compact battery pack. Preferably, the planar size of the external circuit positioned above the terminal mounting surface is the same as or less than the terminal mounting surface.

[0097] (A rechargeable battery that is circular in plan view) In this embodiment, the overall planar shape of the secondary battery is circular. That is, the secondary battery 1000 is button-shaped or coin-shaped in terms of its external form (see, for example, Figure 2).

[0098] The fact that the plan view of a secondary battery is circular means that the shape of the electrode assembly and / or the casing enclosing it can be circular when viewed from above or below.

[0099] The term "circular" as used herein is not limited to a perfect circle (i.e., simply a "circle" or "perfect circle"), but also includes a roughly circular shape that, while modified, can generally be considered a "round shape" by those skilled in the art. For example, it may not only be a circle or a perfect circle, but also one in which the curvature of its arc differs locally, or even a shape derived from a circle or a perfect circle, such as an ellipse. In a typical example, a battery having such a circular shape in plan view corresponds to a so-called button-type or coin-type battery. In one preferred exemplary embodiment, the secondary battery of the present invention is a cylindrical battery.

[0100] In such a circular secondary battery configuration in plan view, the curvature of the outer casing's contour in plan view is arc-shaped, and may have a portion that faces the curved portion of the electrode terminal's contour in plan view, as well as a portion that faces the straight portion of the electrode terminal's contour in plan view. That is, for example, as shown in the plan view of Figures 5(A) to (D), a different arc portion 160b of the outer casing's contour, distinct from the "arc portion 160a of the outer casing 100 that faces the curved portion 254 of the electrode terminal 200," may face the straight portion 252 of the electrode terminal 200.

[0101] In a secondary battery having a circular shape in plan view, the plan view contour of the outer casing opening (i.e., the plan view opening contour) may consist of both straight and curved portions. For example, the shape of the plan view opening contour of such an outer casing opening is similar to the plan view contour of the electrode terminal, and preferably it is a similar shape having a smaller area than the plan view contour of the electrode terminal. In this invention, although the plan view outer contour of the outer casing (i.e., the contour of the outer edge) is circular, the plan view contour of the electrode terminal, the plan view opening contour of the outer casing opening, the plan view outer contour of the insulating seal member and / or the plan view inner contour of the insulating seal member are non-circular, and preferably they may consist of both straight and curved portions.

[0102] In one preferred embodiment, because the battery is button-type or coin-type, the axial dimension of the secondary battery (for example, in the direction normal 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 axial dimension of the secondary battery (for example, in the direction normal to the main surface of the battery) may be the same as or larger than the width dimension (diameter dimension).

[0103] (Small rechargeable battery) In this embodiment, the entire secondary battery is relatively small. In other words, the secondary battery can be a small battery.

[0104] For example, the width dimension of the secondary battery or its casing (for example, the dimension perpendicular to the normal or perpendicular direction of the main surface of the battery) may be on the order of millimeters. For example, the width dimension of the secondary battery or its casing (if the width dimension is not constant, the maximum dimension among them) may be approximately 5 mm to 50 mm, for example, 5 mm to 40 mm, 5 mm to 30 mm, or 5 mm to 20 mm. The lower limit is not limited to 5 mm, but may be 10 mm (excluding 10 mm). That is, the above width dimension of the secondary battery or its casing may be greater than 10 mm and less than or equal to approximately 50 mm, for example, greater than 10 mm and less than or equal to 40 mm, greater than 10 mm and less than or equal to 30 mm, greater than 10 mm and less than or equal to 20 mm, greater than 10 mm and less than or equal to 18 mm, etc. In the case of a cylindrical battery, the width dimension of the secondary battery may correspond to the diameter dimension of the casing (for example, its lid member).

[0105] In a secondary battery according to this embodiment, even though it is so small, the terminal region and the non-terminal region can be more favorably secured on the main surface of the battery. In other words, even though it is a small battery on the order of millimeters (for example, a small cylindrical battery), an external lead member for external connection can be favorably provided in the non-terminal region. For example, such a small battery can have both an external lead member on the positive electrode side and an external lead member on the negative electrode side on a single main surface of the battery.

[0106] The embodiments of the present invention have been described above, but these are merely typical examples. Therefore, those skilled in the art will easily understand that the present invention is not limited thereto and that various embodiments are conceivable.

[0107] For example, the above discussion touched upon a slitting mechanism, or venting mechanism. In a venting mechanism, the conductive member connected to the electrode terminal may have some "play" so that the electrode terminal opens more favorably. In other words, if there is not enough length in the conductive member connected to the electrode terminal, the very existence of the conductive member can become a resistance to the opening of the electrode terminal. Therefore, the length of the conductive member between the electrode assembly and the electrode terminal may be relatively long enough not to unfavorably hinder the opening of the electrode terminal (in particular, it may be longer than the conventional length of the conductive member). In other words, the conductive member may have a length such that excessive tension does not act between the electrode terminal and the electrode assembly to hinder the opening of the electrode terminal. For example, a conductive member extending from the electrode assembly may be connected to the electrode terminal with its deflection and / or bending.

[0108] Furthermore, regarding the venting mechanism, in the secondary battery of the present invention, the electrode terminals may have higher rigidity than the outer casing when compared to the electrode terminals. In other words, at least a portion of the outer casing may have lower rigidity than the electrode terminals. For example, the outer casing portion having the surface on which the electrode terminals are located may have lower rigidity than the electrode terminals themselves. Conversely, the electrode terminals may have relatively higher rigidity than the outer casing portion having the surface on which they are located. Such differences in rigidity contribute to the realization of a more suitable venting mechanism. In the event of an abnormality such as excessively high internal cell pressure, the electrode terminals become less likely to deform due to their high rigidity, while the outer casing portion constituting the surface on which the electrode terminals are located can deform, making it easier for the bonding surface of the insulating seal member to peel off and for the electrode terminals to open. This is merely one example, but the thickness of the outer casing portion forming the surface on which the electrode terminals are located (for example, the thickness of the lid-shaped member when the outer casing is composed of a lid-shaped member and a cup-shaped member) may be 170 μm or less. If the thickness of such an outer casing is 170 μm or less, the casing becomes more prone to deformation in abnormal situations such as excessively high internal cell pressure, and the electrode terminals become more likely to open as a venting mechanism. In other words, if the thickness of the outer casing is greater than 170 μm (for example, 200 μm or more), the casing becomes less prone to deformation in abnormal situations, and the intended opening of the electrode terminals 200 becomes less likely. There is no particular lower limit to the thickness of such a thin outer casing, but it may be, for example, between 50 μm and 170 μm. Note that in the case where an opening 150 is provided in the lid-shaped member 100B of the outer casing 100 shown in Figure 4 and the electrode terminals 200 are arranged therein, the thickness of the lid-shaped member 100B may be less than the thickness of the electrode terminals 200. The lid-shaped member 100B alone constitutes the "outer casing that provides the surface on which the electrode terminals are arranged," so it is easy to provide it as a thin member, and therefore it is prone to bending or deforming.

[0109] Furthermore, although the above describes an embodiment in which the exterior body is composed of a cup-shaped member and a lid-shaped member, 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 cup-shaped members. In other words, the exterior body may be composed of at least a first metal exterior body which is a cup-shaped member and a second metal exterior body which is also a cup-shaped member. In this case, the first metal exterior body and the second metal exterior body which are cup-shaped members may be combined so that their side walls meet to form the exterior body. The above-mentioned "exterior body opening" may be provided in either the first metal exterior body or the second metal exterior body which is a cup-shaped member, and therefore, electrode terminals and insulating seal members may be provided on that cup-shaped member. Moreover, although it has been mentioned that when the exterior body is composed of a cup-shaped member and a lid-shaped member, the exterior body opening is provided on the lid-shaped member, the present invention is not necessarily limited to this. The exterior body opening may be provided on the cup-shaped member.

[0110] Furthermore, although the above describes an embodiment in which the insulating seal member 300 is provided on the outer casing 100 so as to protrude outward from the electrode terminal 200 (Figure 10), the present invention is not necessarily limited to this. The insulating seal member may be provided so as to be hidden beneath the electrode terminal without protruding outward from the electrode terminal. For example, the insulating seal member may be provided only at approximately the same distance as the outer edge of the electrode terminal or only inside of it.

[0111] Furthermore, while the above describes a configuration in which the end portions of the straight section and the curved section of the electrode terminal are shared with each other in terms of the planar contour, there are no particular restrictions on the shape of the shared portion between the straight section and the curved section. For example, the planar shape of the shared portion between the straight section and the curved section may be rounded or angular.

[0112] Furthermore, although the non-terminal region was mentioned above, it may specifically refer to the region mentioned in the [Examples] described later. In other words, a virtual straight line L obtained by further extending the straight contour of the electrode terminal. vOf the region enclosed by the outer contour 160 of the outer casing, the region R on the side that does not include the electrode terminals 200 may be considered a "non-terminal region" (see the right side of Figure 16(B)). If there are multiple straight contours, the sum of the regions similarly formed for each straight contour (including one of the overlapping areas) may be considered the non-terminal region.

[0113] In this disclosure, "the plan view contour of the electrode terminal on the surface in contact with the insulating seal member" may be simply considered as "the outer contour of the electrode terminal when the secondary battery is viewed from the outside." Similarly, "the plan view contour of the casing on the surface in contact with the insulating seal member" may be simply considered as "the outer contour of the casing when the secondary battery is viewed from the outside (particularly from the battery surface on which the electrode terminals are installed)." For example, if the casing includes the aforementioned lid-like member and the lid-like member has an opening (an opening through which a conductive member passes), the plan view contour, the plan view outer contour, or the outermost plan view contour of the lid-like member may be considered as "the plan view contour of the casing on the surface in contact with the insulating seal member." Furthermore, if the lid-shaped member has a form in which its outer edge is bent toward the outside of the battery, as shown in Figures 3(A) and 3(B) and Figure 10, the plan view contour formed by the portion excluding the bent outer edge can be considered as the "plan view contour of the outer casing on the surface where the outer casing contacts the insulating seal member" (this is merely an example, but in Figure 3, the contour shown by reference numeral 160' can be considered as such an intended contour). Alternatively, the plan view contour of the lid-shaped member formed by the entire member, including the bent outer edge (i.e., the plan view contour when the lid-shaped member is viewed from the outside as a whole, including the outer edge), can be considered as the "plan view contour of the outer casing on the surface where the outer casing contacts the insulating seal member." Furthermore, if the lid-shaped member and the cup-shaped member are airtightly assembled in the exterior body, and as a result the outer edge contours of the lid-shaped member and the cup-shaped member have the same shape (for example, substantially the same or similar shape) in a plan view, then the plan view outer edge contour of the cup-shaped member may be considered as the "plan view contour of the exterior body at the surface where the exterior body contacts the insulating seal member."

[0114] The embodiments of the secondary battery described herein are as follows: <1> electrode assembly, An outer casing for housing the electrode assembly, and Electrode terminals arranged on the exterior body and electrically connected to the electrode assembly via conductive members. It consists of having, The electrode terminal and the outer casing are bonded together by an insulating sealing member (or insulating member) interposed between the electrode terminal and the outer casing, and provided around the opening of the outer casing through which the conductive member passes. A secondary battery in which the plan view contour of the electrode terminal on the surface in contact with the insulating seal member consists of both a straight portion and a curved portion, the plan view contour of the outer casing on the surface in contact with the insulating seal member includes a curve, and the curved portion of the electrode terminal and a part of the curve of the outer casing face each other. <2> The straight portion of the electrode terminal is opposite to the curved portion of the outer casing, which is different from the part of the outer casing. <1> The secondary battery described above. <3> In the plan view contour of the electrode terminal, the straight portion and the curved portion are continuous, such that one end portion of the straight portion and one end portion of the curved portion are shared with each other. <1> or <2> The secondary battery described above. <4> The proportion of the curved portion to the plan view contour of the electrode terminal is relatively larger than the proportion of the straight portion. <1> ~ <3> A rechargeable battery as described in one of the following. <5> In the plan view contour of the electrode terminal, the curved portion is arc-shaped. <1> ~ <4> A rechargeable battery as described in one of the following. <6> The curved portion of the electrode terminal is positioned relatively closer to the curve of the outer casing than the straight portion of the electrode terminal. <1> ~ <5> A rechargeable battery as described in one of the following. <7> It comprises two external lead members for external connection, where both the external lead members and the other are provided on the same main surface of the battery, and the same main surface of the battery corresponds to the battery surface composed of the electrode terminals and the outer casing. <1> ~ <6> A rechargeable battery as described in one of the following. <8> One of the external lead members is provided with respect to the electrode terminals, and the other of the external lead member is provided with respect to the non-terminal region of the same main surface of the battery, which is a region other than the electrode terminals. <7> The secondary battery described above. <9> The plan view contour of the electrode terminal is formed from a single straight section and a single curved section. <1> ~ <8> A rechargeable battery as described in one of the following. <10> The plan view of the opening of the exterior body is composed of both a straight portion and a curved portion. <1> ~ <9> A rechargeable battery as described in one of the following. <11> The plan view contour of the insulating sealing member is composed of both a straight portion and a curved portion. <1> ~ <10> A rechargeable battery as described in one of the following. <12> The electrodes of the electrode assembly include a positive electrode and a negative electrode capable of intercalating and deintercalating lithium ions. <1> ~ <11> A rechargeable battery as described in one of the following. [Examples]

[0115] Model studies were conducted in relation to the present invention. Specifically, simulations were performed regarding the area of ​​the non-terminal region on the main surface of the battery.

[0116] The assumed base virtual battery 1000' is shown in Figures 15(A) and 15(B). The following conditions were set for this virtual battery. The battery has a cylindrical shape overall. Electrode terminals are attached to the top surface of the cylindrical battery via an insulating sealing member. The lid member is joined to the can member by laser welding on its outer circumference. The outer diameter (a) of the lid member shall be 12 mm. • To prevent the thermal effects of laser welding on the outer circumference of the lid member from affecting the insulating seal member, the distance (b) between the outer diameter of the lid member and the insulating seal member shall be 1 mm or more. The insulating sealant should be slightly larger than the electrode terminals, with a clearance (c) of 0.5 mm on each side. • The sealing distance (d) to ensure adhesive strength and long-term reliability shall be 1.5 mm or more. • The cover hole size required for connecting the internal conductive tabs inside the cell shall be such that the short side distance (e) of the hole is 4 mm or more. Based on the above premise, schematic diagrams modeling the configurations of the embodiment and comparative example are shown in Figure 16(A). In Figure 16(A), the can components are omitted, and the lid component is also depicted as a simple flat plate shape.

[0117] Regarding the modeled Figure 16(A), Figure 16(B) shows a schematic diagram comparing the effective area of ​​the non-terminal region (hereinafter simply referred to as the "non-terminal region area") that can be substantially used for installing the external lead member in the lid member between the example and the comparative example. As shown in Figure 16(B), it was found that the example could achieve a larger non-terminal region area R, and thus secure a wider area for connecting the external lead member. Furthermore, Figure 17 shows a graph of the change in the non-terminal region area when the dimension a (outer diameter of the lid member) is changed under the given conditions. As shown in the graph of Figure 17, it was found that under the given conditions, when dimension a is greater than φ10 mm, it can be substantially significant in terms of the non-terminal region area, and this becomes more pronounced as dimension a increases.

[0118] It should be noted that the effects described in the above examples are merely illustrative. Therefore, the present invention is not limited to the matters described above, and additional effects may also be present. [Industrial applicability]

[0119] The secondary battery according to the present invention can be used in various fields where battery use or energy storage is anticipated. Although these are merely examples, the secondary battery of the present invention can be used in the electrical, information, and communication fields where electrical and electronic equipment is used (for example, the electrical and electronic equipment field or mobile device field including mobile phones, smartphones, laptops and digital cameras, activity trackers, ARM computers, electronic paper, wearable devices, and small electronic devices such as RFID tags, card-type electronic money, and smartwatches), household and small industrial applications (for example, power tools, golf carts, and household, nursing care, and industrial robots), large industrial applications (for example, forklifts, elevators, and port cranes), transportation systems (for example, hybrid cars, electric vehicles, buses, trains, electric assist bicycles, and electric motorcycles), power grid applications (for example, various power generation systems, road conditioners, smart grids, and general household energy storage systems), medical applications (medical equipment such as earphones and hearing aids), pharmaceutical applications (medication management systems, etc.), as well as IoT applications and space and deep-sea applications (for example, space probes and submersible research vessels).

[0120] Finally, I would like to add a note regarding the disclosures in "Japanese Patent Publication No. 2019-046639" (Patent Document 1) and "Japanese Patent Publication No. 2020-202071" (Patent Document 2). In the battery shown in Patent Document 1, the electrode terminal diameter is large, and the exposed area of ​​the outer casing on the battery surface where the electrode terminals are provided is small. Therefore, it is not usually assumed that a component for external output (e.g., a tab) will be connected to the outer casing surface of the battery. Furthermore, in the structure of Patent Document 2, two circular electrode terminals are attached to the same surface of the battery, so the terminals themselves are small, and it is not possible to secure a large sealing area for the insulating sealing member at each individual terminal. In other words, even if the initial airtight sealing of the battery is ensured in the configuration shown in Patent Document 2, because the two terminals are individually smaller, the amount of electrolyte evaporation from inside the cell and the amount of moisture intrusion from outside the cell may increase, and it is thought that the long-term reliability of the battery cannot be guaranteed. In addition, the adhesive strength of the electrode terminals cannot be increased. [Explanation of symbols]

[0121] 1 positive electrode 2 negative electrode 5 Electrode configuration 10 Electrode assembly 100 Exterior 100A Cup-shaped member 100B Lid-shaped member 110A terminal area 110B Non-terminal area 150 Exterior body opening 155 Exterior body opening edge 158 Exterior body surface 160 Planar view contour of the exterior / Outer contour of the exterior (outer contour of the secondary battery) 160' Planar view contour of the casing / Outer contour of the casing (outer contour of the secondary battery) 160a The curved outer contour of the outer casing facing the curved contour of the electrode terminal in plan view 160b The curved portion of the outer contour of the casing that faces the straight contour of the electrode terminal in a plan view. 180 Outline of exterior body opening 182 Straight section of the outline of the exterior opening 184 Curved part of the outline of the exterior opening 200 electrode terminal 250 Planar view contour of electrode terminals 252 Straight section 252a One end of the straight section 252b The other end of the straight section 252c Half-section point of the straight section 254 Curved section 254' Arc contour 254a One end portion of the curved section 254b The other end of the curved section 254c Half-section point of the curved section 300 Insulating sealing material 350 Outer contour of insulating sealing member 352 Straight portion of the outer contour of the insulating sealing member 354 Curved portion of the outer contour of the insulating sealing member 360 Inner contour of insulating sealing member 362 Straight portion of the inner contour of the insulating sealing member 364 Curved portion of the inner contour of the insulating sealing member 400 Conductive material 500A External Outlet Member 500B External Outlet Member 600 terminals on the battery side (same main battery side) 1000 secondary battery Lw: The distance (shortest distance) between the curved portion of the electrode terminal and the outer contour of the casing. The distance (shortest distance) between the straight portion of the Ls electrode terminal and the outer contour of the casing. Lv Extending the straight contour line (virtual line) M Battery center U Curvature Maximum Point Virtual battery assumed in 1000' simulation 100' Outer casing in a virtual battery 100B' Lid-like member in virtual battery Electrode terminals in a 200' virtual battery 300' Insulating sealing member in virtual battery

Claims

1. electrode assembly, An outer casing for housing the electrode assembly, and The exterior body is arranged and has electrode terminals that are electrically connected to the electrode assembly via a conductive member, The electrode terminal and the outer casing are bonded together by an insulating sealing member interposed between them and provided around the opening in the outer casing through which the conductive member passes. The plan view contour of the electrode terminal on the surface in contact with the insulating seal member consists of both a straight portion and a curved portion, the plan view contour of the outer casing on the surface in contact with the insulating seal member includes a curve, and the curved portion of the electrode terminal and a part of the curve of the outer casing face each other. A secondary battery comprising two external lead members for external connection, wherein both the external lead members and the other are provided on the same main surface of the battery, and the same main surface of the battery corresponds to the battery surface composed of the electrode terminals and the outer casing.

2. Electrode assembly, An outer casing for housing the electrode assembly, and It has electrode terminals arranged on the outer casing and electrically connected to the electrode assembly via a conductive member, The electrode terminal and the outer casing are bonded together by an insulating sealing member interposed between them and provided around the opening in the outer casing through which the conductive member passes. The plan view contour of the electrode terminal on the surface in contact with the insulating seal member consists of both a straight portion and a curved portion, the plan view contour of the outer casing on the surface in contact with the insulating seal member includes a curve, and the curved portion of the electrode terminal and a part of the curve of the outer casing face each other. A secondary battery in which the plan view contour of the electrode terminal is formed from a single straight portion and a single curved portion.

3. Electrode assembly, An outer casing for housing the electrode assembly, and It has electrode terminals arranged on the outer casing and electrically connected to the electrode assembly via a conductive member, The electrode terminal and the outer casing are bonded together by an insulating sealing member interposed between them and provided around the opening in the outer casing through which the conductive member passes. The plan view contour of the electrode terminal on the surface in contact with the insulating seal member consists of both a straight portion and a curved portion, the plan view contour of the outer casing on the surface in contact with the insulating seal member includes a curve, and the curved portion of the electrode terminal and a part of the curve of the outer casing face each other. A secondary battery in which the plan view of the opening of the exterior body is composed of both a straight portion and a curved portion.

4. The secondary battery according to claim 1, wherein the straight portion of the electrode terminal faces the curved portion of the outer casing, which is different from the part of the outer casing.

5. The secondary battery according to claim 1, wherein one end portion of the straight portion and one end portion of the curved portion are shared with each other such that the straight portion and the curved portion are continuous in the plan view contour of the electrode terminal.

6. The secondary battery according to claim 1, wherein the proportion of the curved portion to the plan view contour of the electrode terminal is greater than the proportion of the straight portion.

7. The secondary battery according to claim 1, wherein the curved portion of the electrode terminal's contour in plan view is arc-shaped.

8. The secondary battery according to claim 1, wherein the curved portion of the electrode terminal is positioned relatively closer to the curve of the outer casing than the straight portion of the electrode terminal.

9. The secondary battery according to claim 1, wherein one of the external lead members is provided with respect to the electrode terminals, and the other of the external lead member is provided with respect to a non-terminal region of the same main surface of the battery other than the electrode terminals.

10. The secondary battery according to claim 1, wherein the plan view contour of the insulating sealing member is composed of both a straight portion and a curved portion.

11. The secondary battery according to claim 1, 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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