Secondary battery

Abstract

Provided is a secondary battery having an electrode assembly and an exterior member accommodating the electrode assembly. The exterior member of the secondary battery includes a metal plate joined via an insulating material, and the metal plate serves as an external output terminal.

Description

Technical Field

[0001] The present invention relates to a secondary battery, and more particularly to a secondary battery having an electrode assembly including an electrode structure layer including a positive electrode, a negative electrode, and a separator. Background Art

[0002] Secondary batteries are so-called storage batteries, and therefore can be repeatedly charged and discharged, and are used for various purposes. For example, mobile devices such as mobile phones, smartphones, and notebook personal computers use secondary batteries.

[0003] In view of various battery applications including mobile devices, secondary batteries are provided with output terminals and are connected to external devices for use.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application No. 2015-536036 Summary of the invention

[0007] Technical problem to be solved by the invention

[0008] The inventors of the present application have noticed that there are technical problems in existing secondary batteries that should be overcome, and found that measures need to be taken to address them. Specifically, the inventors of the present application have found the following technical problems.

[0009] The secondary battery comprises an electrode assembly and an outer casing that wraps the electrode assembly. The electrode assembly is formed by stacking electrode structure layers including a positive electrode, a negative electrode, and a separator therebetween. The outer casing is provided with an output terminal, namely, an external output terminal, for connection with an external device.

[0010] The external output terminal is usually a rivet-type structure and is installed by riveting a metal rivet member. Due to the "riveting", the metal rivet part is deformed and the insulating part is pressed to achieve sealing.

[0011] Specifically, for Fig.19 For the rivet-type external output terminal shown in the figure, due to "riveting", the metal rivet component 80' is deformed in such a way that its trunk portion 85' becomes thicker, and the insulating portion 90' located between the trunk portion 85' of the metal rivet component 80' and the outer component 50' is compressed by such deformation. In particular, the area 95' of the insulating portion 90' that exists near the edge of the outer component 50' is greatly compressed. Therefore, if the compressive force accompanying the "riveting" is excessive, the area 95' of the insulating portion 90' may become extremely thin or disconnected, and the required sealing force may not be provided. In other words, in such a case, it results in a terminal that is not needed as an external output terminal of the secondary battery.

[0012] The present invention has been made in view of such technical problems. That is, a main object of the present invention is to provide a secondary battery having a more preferable external output terminal.

[0013] Technical solutions for solving technical problems

[0014] The inventors of the present application have attempted to solve the above technical problems by taking a new approach rather than responding to the existing technology by extending it. As a result, they have invented a secondary battery that achieves the above main purpose.

[0015] The present invention provides a secondary battery comprising an electrode assembly and an exterior member for housing the electrode assembly. In the secondary battery, the exterior member includes a metal plate joined via an insulating material, and the metal plate serves as an external output terminal.

[0016] Effects of the Invention

[0017] The secondary battery of the present invention includes a more preferred external output terminal.

[0018] Specifically, in the present invention, when an external output terminal is formed by attaching a metal plate to an exterior member via an insulating material, "riveting" is not performed. In other words, when the metal plate is attached to the exterior member, no large force is applied to the metal plate to the extent that the metal plate is deformed. Therefore, for the external output terminal involved in the present invention, the required sealing force is provided and the possibility of extreme thinning or disconnection of the insulating material is also reduced, resulting in a more preferred secondary battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a cross-sectional view schematically showing the structure of an electrode assembly ( Figure 1 (A): Non-wound planar laminated type, Figure 1 (B): winding type).

[0020] Figure 2 2 is a schematic cross-sectional view showing the structure of an external output terminal of a secondary battery according to an embodiment of the present invention. Figure 2 (A): The outer side of the metal plate is configured. Figure 2 (B): configuration on the inner side of the metal plate).

[0021] Figure 3 is a schematic cross-sectional view of a secondary battery according to an embodiment for explaining the structure of an exterior member ( Figure 3 (A): The outer side of the metal plate is configured. Figure 3 (B): configuration on the inner side of the metal plate).

[0022] Figure 4This is a schematic cross-sectional view of a secondary battery according to an embodiment for explaining the structure of an exterior member.

[0023] Figure 5 is a schematic cross-sectional view of a secondary battery according to one embodiment of the present invention ( Figure 5 (A): An external output terminal is provided on a cup-shaped member of a wound electrode assembly / exterior member. Figure 5 (B): An external output terminal is provided on the lid-like member of the wound electrode assembly / exterior member).

[0024] Figure 6 This is a schematic cross-sectional view for explaining the manner in which the external output terminal is positioned inside the exterior member.

[0025] Figure 7 This is a schematic cross-sectional view for explaining a modified form of an external output terminal positioned inside the exterior member.

[0026] Figure 8 This is a schematic cross-sectional view for explaining the manner in which the external output terminal is positioned outside the exterior member.

[0027] Fig. 9 This is a schematic cross-sectional view for explaining a modified form of an external output terminal positioned outside the exterior member.

[0028] Fig.10 This is a schematic cross-sectional view for explaining the ventilation function of the external output terminal.

[0029] Fig.11 This is a schematic cross-sectional view for explaining the “thin-wall method of the exterior member”.

[0030] Fig.12 This is a schematic cross-sectional view for explaining the "method of special insulating material structure".

[0031] Fig.13 This is a schematic cross-sectional view for explaining the “special thickness form of the insulating material”.

[0032] Fig.14 (A)~ Fig.14 (C) is a schematic cross-sectional view for explaining a change in the arrangement of the external output terminals.

[0033] Fig.15 (a)~ Fig.15 (d) is a schematic perspective view for illustrating various forms of secondary batteries, such as button-type, coin-type, and square-type.

[0034] Fig.16 (a) to (d) are schematic perspective views for illustrating various shapes (circular and quadrilateral / rectangular) of the metal plate of the external output terminal.

[0035] Fig.17 This is a schematic cross-sectional view for explaining a case where a resin layer for insulation is additionally provided.

[0036] Fig.18 This is a schematic cross-sectional view for explaining a certain modification of the present invention.

[0037] Fig.19 It is a schematic cross-sectional view showing the structure of a conventional rivet-type output terminal (prior art). DETAILED DESCRIPTION

[0038] The secondary battery according to one embodiment of the present invention is described in more detail below. The description will be made with reference to the drawings as needed, but the various elements in the drawings are merely schematically and exemplarily shown for the purpose of understanding the present invention, and the appearance and / or dimensional ratios may differ from the actual objects.

[0039] The "section view" directly or indirectly described in this specification refers to an imaginary cross-section of a secondary battery cut along the stacking direction of the electrode assembly or electrode structure layer constituting the secondary battery. Similarly, the direction of the "thickness" directly or indirectly described in this specification is based on the stacking direction of the electrode material constituting the secondary battery. For example, in the case of a "secondary battery having a thickness in a plate shape" such as a button type or a coin type, the direction of "thickness" is equivalent to the plate thickness direction of such a secondary battery. The "top view" used in this specification refers to a schematic view based on observing an object from the top or bottom along such a thickness direction.

[0040] In addition, the "up and down direction" and "left and right direction" used directly or indirectly in this specification correspond to the up and down direction and left and right direction in the figure, respectively. Unless otherwise specified, the same reference numerals or symbols represent the same parts or parts or the same meanings. In a preferred embodiment, it can be observed that the vertical direction downward (i.e., the direction in which gravity acts) corresponds to the "downward direction", and the opposite direction corresponds to the "upward direction".

[0041] Unless otherwise specified by specific terms such as "less than", "more than / greater than", etc., the various numerical ranges mentioned in this specification refer to the numerical values ​​themselves including the lower limit and the upper limit. In other words, for example, a numerical range of 1 to 10 can be interpreted as including the lower limit "1" and also including the upper limit "10".

[0042] [Basic structure of secondary battery]

[0043] The term "secondary battery" as used herein refers to a battery that can be repeatedly charged and discharged. Therefore, the secondary battery of the present invention is not limited to its name, and may include, for example, power storage devices.

[0044] The secondary battery according to the present invention includes an electrode assembly formed by stacking electrode structure layers including a positive electrode, a negative electrode, and a separator. Figure 1 Example of electrode assembly 10. As shown in the figure, positive electrode 1 and negative electrode 2 are stacked with separator 3 to form electrode structure layer 5, and at least one such electrode structure layer 5 is stacked to form electrode assembly 10. In a secondary battery, such an electrode assembly is sealed in an outer casing together with an electrolyte (such as a non-aqueous electrolyte). In addition, the structure of the electrode assembly is not necessarily limited to a planar stacking structure (see Figure 1 (A)), for example, it may have a winding structure in which an electrode unit (electrode structure layer) including a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode is wound in a roll shape (see Figure 1 In other words, for example Figure 1 As shown in (A), the electrode assembly 10 may have a structure in which the electrode structure layers 5 are stacked one on another. Alternatively, for example, Figure 1 As shown in (B), the electrode assembly 10 may also have a winding structure in which the electrode structure layer 5 extending long in a strip shape is wound in a roll shape. In addition, for example, the electrode assembly may also have a so-called stack-folded structure in which the positive electrode, the separator, and the negative electrode are stacked on a long film and then folded.

[0045] The positive electrode is composed of at least a positive electrode material layer and a positive electrode current collector. In the positive electrode, a positive electrode material layer is provided on at least one side of the positive electrode current collector, and the positive electrode material layer contains a positive electrode active material as an electrode active material. For example, the plurality of positive electrodes of the electrode assembly may also be provided with positive electrode material layers on both sides of the positive electrode current collector, or may be provided with a positive electrode material layer only on one side of the positive electrode current collector.

[0046] The negative electrode is composed of at least a negative electrode material layer and a negative electrode current collector. In the negative electrode, a negative electrode material layer is provided on at least one side of the negative electrode current collector, and the negative electrode material layer contains a negative electrode active material as an electrode active material. For example, the multiple negative electrodes of the electrode assembly may also be provided with negative electrode material layers on both sides of the negative electrode current collector, or may be provided with a negative electrode material layer only on one side of the negative electrode current collector.

[0047] The electrode active material contained in the positive electrode and the negative electrode, namely the positive electrode active material and the negative electrode active material, is a material that directly participates in the transfer of electrons in the secondary battery, and is the main material of the positive and negative electrodes that bear the charge and discharge, namely the battery reaction. More specifically, ions are generated in the electrolyte because of 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 such ions move between the positive electrode and the negative electrode to transfer electrons, thereby performing charge and discharge. The positive electrode material layer and the negative electrode material layer can especially be a layer that can absorb and release lithium ions. In other words, the secondary battery involved in the present invention can be a non-aqueous electrolyte secondary battery in which lithium ions move between the positive electrode and the negative electrode via a non-aqueous electrolyte to charge and discharge the battery. In the case where lithium ions participate in charge and discharge, the secondary battery involved in the present invention is equivalent to a so-called "lithium ion battery", and the positive electrode and the negative electrode have a layer that can absorb and release lithium ions.

[0048] In the case where the positive electrode active material of the positive electrode material layer is composed of, for example, granules, it is preferred that the positive electrode material layer contains a binder for more sufficient contact and shape retention of the particles. Furthermore, it may be that the positive electrode material layer contains a conductive aid in order to facilitate the transfer of electrons that promote the battery reaction. Similarly, in the case where the negative electrode active material of the negative electrode material layer is composed of, for example, granules, it may also contain a binder for more sufficient contact and shape retention of the particles, and the negative electrode material layer may also contain a conductive aid in order to facilitate the transfer of electrons that promote the battery reaction. In this way, because it is a form containing multiple components, the positive electrode material layer and the negative electrode material layer can also be referred to as "positive electrode composite material layer" and "negative electrode composite material layer" respectively.

[0049] The positive electrode active material may also be a material that contributes to the absorption and release of lithium ions. From such a point of view, the positive electrode active material may be, for example, a lithium-containing composite oxide. More specifically, the positive electrode active material may be a lithium transition metal composite oxide containing lithium and at least one transition metal selected from the group consisting of cobalt, nickel, manganese and iron. In other words, in the positive electrode material layer of the secondary battery involved in the present invention, it is preferred to include such a lithium transition metal composite oxide as a positive electrode active material. For example, the positive electrode active material may also be lithium cobaltate, lithium nickelate, lithium manganate, lithium iron phosphate or a material in which a part of their transition metals is replaced by other metals. Such a positive electrode active material may include one alone or two or more in combination.

[0050] The binder that can 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 cited. The conductive additive that can be included in the positive electrode material layer is not particularly limited, but at least one selected from the group consisting of thermal black, furnace black, channel black, Ketjen black and acetylene black; carbon fibers such as graphite, carbon nanotubes and vapor-grown carbon fibers; metal powders such as copper, nickel, aluminum and silver; and polyphenyl derivatives can be cited.

[0051] The thickness of the positive electrode material layer is not particularly limited, but may be 1 μm to 300 μm, for example 5 μm to 200 μm. The thickness of the positive electrode material layer is the thickness inside the secondary battery, and may be the average value of the measured values ​​at any 10 locations.

[0052] The negative electrode active material may be a material that contributes to the absorption and release of lithium ions. From such a viewpoint, the negative electrode active material may be, for example, various carbon materials, oxides, and / or lithium alloys.

[0053] As various carbon materials for negative electrode active materials, there are: graphite (natural graphite, artificial graphite), hard carbon, soft carbon, diamond-like carbon, etc. In particular, graphite has high electronic conductivity and excellent adhesion to the negative electrode collector. As oxides for negative electrode active materials, there are: at least one selected from the group consisting of silicon oxide, tin oxide, indium oxide, zinc oxide, and lithium oxide. The lithium alloy of the negative electrode active material can be any metal that can form an alloy with lithium, for example, it can be a binary, ternary or higher alloy of metals such as Al, Si, Pb, Sn, In, Bi, Ag, Ba, Ca, Hg, Pd, Pt, Te, Zn, La and lithium. Such oxides can be amorphous as their structural form. This is because it is not easy to produce degradation caused by unevenness such as grain boundaries or defects.

[0054] As a binder that can be included in the negative electrode material layer, although there is no particular limitation, it can be cited as: at least one selected from the group consisting of styrene-butadiene rubber, polyacrylic acid, polyvinylidene fluoride, polyimide resin and polyamide-imide resin. As a conductive aid that can be included in the negative electrode material layer, although there is no particular limitation, it can be cited as: carbon black selected from thermal black, furnace black, channel black, Ketjen black and acetylene black; carbon fibers such as graphite, carbon nanotubes and vapor-grown carbon fibers; metal powders such as copper, nickel, aluminum and silver; and at least one of polyphenyl derivatives. In addition, the negative electrode material layer may also contain a component generated from a thickener component (such as carboxymethyl cellulose) used in battery manufacturing.

[0055] The thickness of the negative electrode material layer is not particularly limited, but may be 1 μm to 300 μm, for example 5 μm to 200 μm. The thickness of the negative electrode material layer is the thickness inside the secondary battery, and may be the average of values ​​measured at any 10 locations.

[0056] The positive electrode collector and the negative electrode collector for the positive electrode and the negative electrode are components that help to gather or supply electrons generated by the electrode active material due to the battery reaction. Such an electrode collector can be a sheet-like metal component. In addition, such an electrode collector can also have a porous or perforated form. For example, the collector can be a metal foil, a punched metal, a mesh or a metal plate mesh, etc. The positive electrode collector for the positive electrode is preferably composed of a metal foil selected from at least one of the groups consisting of aluminum, stainless steel, and nickel, for example, aluminum foil. On the other hand, the negative electrode collector for the negative electrode is preferably composed of a metal foil selected from at least one of the groups consisting of copper, stainless steel, and nickel, for example, copper foil.

[0057] The thickness of the positive electrode collector and the negative electrode collector is not particularly limited, but can be 1 μm or more and 100 μm or less, for example, 10 μm or more and 70 μm or less. The thickness of the positive electrode collector and the negative electrode collector is the thickness inside the secondary battery, and the average value of the measured values ​​of any 10 locations can be used.

[0058] The separator used for the positive electrode and the negative electrode is a component provided from the viewpoint of preventing a short circuit caused by contact between the positive and negative electrodes and maintaining the electrolyte. In other words, the separator can be said to be a component that prevents electronic contact between the positive electrode and the negative electrode and allows ions to pass through. For example, the separator may be a porous or microporous insulating component having a film shape due to its small thickness. Although it is only an example, a microporous film made of polyolefin can be used as a separator. In this regard, the microporous film used as a separator may, for example, contain only polyethylene (PE) or only polypropylene (PP) as a polyolefin. Further, the separator may be a laminate consisting of a "microporous film made of PE" and a "microporous film made of PP". The surface of the separator may also be covered with an inorganic particle coating layer and / or an adhesive layer. The surface of the separator may have adhesiveness. In addition, in the present invention, the separator should not be particularly limited because of its name, and may also be a solid electrolyte, a gel electrolyte and / or an insulating inorganic particle having the same function.

[0059] The thickness of the separator is not particularly limited, but can be greater than 1 μm and less than 100 μm, for example, greater than 2 μm and less than 20 μm. The thickness of the separator is the thickness inside the secondary battery (especially the thickness between the positive electrode and the negative electrode), and the average value of the measured values ​​at any 10 locations can be used.

[0060] In the secondary battery of the present invention, an electrode assembly consisting of an electrode structure layer including a positive electrode, a negative electrode and a separator is sealed in an outer casing together with an electrolyte. The electrolyte can assist the movement of metal ions released from the electrode (positive electrode and / or negative electrode). The electrolyte can be a "non-aqueous" electrolyte such as an organic electrolyte and an organic solvent, or it can also be an "aqueous" electrolyte containing water. In the case where the positive electrode and the negative electrode have a layer that can absorb and release lithium ions, the electrolyte is preferably a "non-aqueous" electrolyte containing an organic electrolyte / organic solvent, etc. That is, the electrolyte is preferably a non-aqueous electrolyte. Metal ions released from the electrode (positive electrode and / or negative electrode) are present in the electrolyte, so the electrolyte assists the movement of metal ions in the battery reaction. In addition, the electrolyte may also have a liquid or gel-like form.

[0061] A non-aqueous electrolyte is an electrolyte containing a solvent and a solute. As a specific solvent of a non-aqueous electrolyte, it can also be composed of at least a carbonate. Such a carbonate can be a cyclic carbonate and / or a chain carbonate. Although there is no particular restriction, as a cyclic carbonate, at least one selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC) and vinylene carbonate (VC) can be cited. As a chain carbonate, at least one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC) and dipropyl carbonate (DPC) can be cited. Although it is just an example, as a non-aqueous electrolyte, a combination of cyclic carbonates and chain carbonates can also be used, for example, a mixture of ethylene carbonate and diethyl carbonate can also be used. In addition, as a specific solute of a non-aqueous electrolyte, for example, Li salts such as LiPF6 and / or LiBF4 can be used.

[0062] The external component of the secondary battery is a component that can accommodate or enclose an electrode assembly formed by stacking electrode structure layers including a positive electrode, a negative electrode, and a separator. Although described later, in the present invention, the external component may also be a metal external component having a non-laminated structure.

[0063] [Features of the Secondary Battery of the Present Invention]

[0064] The secondary battery of the present invention has a feature in the structure of its external output terminal. In other words, the secondary battery has a feature in the structure of the output terminal for connection with an external device. Specifically, the exterior member has a metal plate joined via an insulating material, and the metal plate becomes the external output terminal.

[0065] like Figure 2As shown in (A) and (B), in the secondary battery of the present invention, the external output terminal 60 is composed of at least a metal plate 62 and an insulating material 64. An opening 55 is provided in the outer casing 50, and a metal plate 62 is arranged on the outer casing surface around the opening 55 via the insulating material 64.

[0066] The metal plate 62 is preferably bonded to the exterior member 50 via the insulating material 64 because of the bonding property of the insulating material 64. It can be said that the metal plate 62 is bonded to the exterior member 50 via the insulating material 64 in the area around the opening 55 provided in the exterior member 50. The tab extending from the electrode assembly is connected to the metal plate. More specifically, Figure 3 As shown in FIG. 5 , the electrode tab 70 extending from the electrode assembly is attached to the metal plate 62 provided in the opening 55. In other words, the conductive electrode tab 70 of either the positive electrode or the negative electrode extending from the electrode assembly is connected to the inner side surface of the metal plate 62 of the exterior member 50. In particular, as shown in FIG. Figure 3 As shown in FIG. 5A , when the metal plate 62 is positioned outside the exterior member 50 , the tab 70 is attached to the metal plate 62 through the opening 55 of the exterior member 50 .

[0067] The pole tab 70 may also be formed by the electrode collector of the electrode assembly. In other words, the pole tab 70 may also be formed by a portion of the electrode collector where no electrode material is provided. Alternatively, the pole tab 70 may also be a collector pin provided on the electrode assembly (particularly, its electrode). Such a collector pin is conductive, and when it is made of metal, for example, it may have a thin-walled shape and / or an elongated shape. Such a conductive pole tab is flexible, and in order to facilitate the ventilation mechanism described later, it may be provided in a flexed shape and / or a bent shape.

[0068] The insulating material 64 may also be provided on the surface of the exterior member along the periphery of the opening 55. For better insulation, the insulating material 64 may be provided so as to extend to a region further outside the metal plate 62. In other words, for example Figure 2 (A) and Figure 2 As shown in (B), the insulating material 64 may be provided on the exterior member 50 in a manner extending outward from the metal plate 62. Similarly, for better insulation, the insulating material 64 may be provided further inside in a manner exceeding the edge of the opening 55 of the exterior member 50. In other words, for example, Figure 2 (A) and Figure 2 As shown in FIG. 5B , the insulating material 64 extends inwardly beyond the edge portion 55 a forming the opening 55 in the exterior member 50 , and therefore a portion of the insulating material 64 may extend to the region of the opening 55 .

[0069] The metal plate 62 may also be in a shape along the outer shape of the outer component. For example, the metal plate 62 is configured to be parallel to the horizontal direction in the figure in a manner along the outer shape of the outer component 50. In other words, in the cross-section as shown in the figure, the metal plate 62 and the surface of the outer component 50 on which it is provided may have a configuration relationship or form that is parallel to each other. In addition, the insulating material may also be configured in a shape along the outer shape of the outer component. For example, similar to the metal plate 62, the insulating material 64 is configured to be parallel to the horizontal direction in the figure in a manner along the outer shape of the outer component 50. In other words, in the cross-section as shown in the figure, the insulating material 64 and the surface of the outer component 50 on which it is provided may also have a configuration relationship or form that is parallel to each other.

[0070] This makes it a relatively simple structure to stick the metal plate to the metal outer component via the insulating material, so it is easy to form a simple and inexpensive secondary battery compared to the existing rivet-type output terminal. In addition, for the external output terminal of the present invention, the space required for sealing is also small, so it helps to miniaturize the battery and can help improve the energy density.

[0071] The external output terminal of the present invention does not include a so-called "riveted" structure (hereinafter, the structure of the terminal not including riveting is also referred to as a "non-riveted structure"). In other words, when the metal plate is attached to the exterior member via the insulating material, no large force is applied to the metal plate to deform the metal plate. Therefore, the required sealing force is provided and the possibility of the insulating material being extremely thinned or disconnected is also reduced. In other words, in the external output terminal of the present invention, the phenomenon of the undesirable condition that the required insulation is damaged is suppressed.

[0072] The metal plate of the present invention is a non-riveted metal plate. In addition, since it is a non-riveted metal plate, the metal plate extends on the same plane when viewed in cross section. In short, the metal plate of the external output terminal as a whole does not have a curved shape but has a flat plate shape. Figure 2 (A) and Figure 2 As shown in (B), the cross-sectional shape of the metal plate 62 forming the external output terminal is, for example, rectangular. Such a metal plate has no history of being deformed by pressure, and is likely to have longer-term stability from the perspective of material. In other words, it is likely to become an external output terminal that is more suitable for long-term use of a secondary battery.

[0073] The metal plate is not particularly limited to the material, and for example, it may be at least one selected from the group consisting of aluminum, nickel, stainless steel (SUS) and copper. The metal plate may also have a plurality of layers consisting of different metal materials. The top view shape of the metal plate is not particularly limited, and for example, it may be circular, or it may be rectangular including quadrilaterals. Appropriate surface treatment may also be performed on the surface of the metal plate. In addition, the "stainless steel" in this specification refers to, for example, stainless steel specified in "JIS G 0203 Steel Terminology", and may also be alloy steel containing chromium or chromium and nickel.

[0074] In one embodiment of the present invention, a non-riveted structure is formed, so that, for example, the insulating material may also extend on the same plane when viewed in cross section. In other words, the cross-sectional shape of the insulating material of the external output terminal is not curved, and may be rectangular, for example. Figure 2 As shown in (A) and (B) of FIG. 2 , the thickness of the insulating material 64 may be substantially constant. Such an insulating material can be said to be an insulating material that further reduces the effect of pressure deformation when the external output terminal is installed.

[0075] The material of the insulating material 64 is not particularly limited as long as it has "insulation" and "bonding properties". The insulating material 64 may also be composed of a resin material. For example, the insulating material 64 may also be composed of a thermoplastic resin. Although this is only a specific example, the insulating material may be composed of a polyolefin such as polyethylene and / or polypropylene.

[0076] The insulating material 64 may also have a film form. In other words, the insulating material 64 may also have a film form, that is, a thin form. For example, the insulating material 64 may be provided using a sheet-like insulating material precursor having a form close to the final shape.

[0077] In the secondary battery of the present invention, the exterior member 50 is preferably a metal exterior member. Figure 4 and Figure 5 (A) and Figure 5 As shown in (B), as an exterior component 50, the metal exterior component may also have a two-part structure of a cup-shaped component 52 and a cover-shaped component 54. The "cup-shaped component" in this specification refers to a component that has a side portion corresponding to a trunk and a main surface portion (typically, such as a bottom portion) continuous therewith, and has a hollow portion formed on the inside. The "cover-shaped component" in this specification refers to a component that is configured to cover such a cup-shaped component. The cover-shaped component may also be, for example, a single component (typically a flat plate-shaped component) extending in the same plane. Alternatively, in the exterior component, the cover-shaped component and the cup-shaped component may be combined in such a manner that the outer edge portion of the cover-shaped component and the upper end portion of the side portion of the cup-shaped component are aligned with each other.

[0078] In the secondary battery of the present invention, the metal outer casing preferably has a non-laminated structure. In other words, the outer casing preferably does not have a laminated structure as a whole. Therefore, in the present invention, the metal outer casing does not become a laminated component such as a metal sheet / welding layer / protective layer. It can be said that the metal outer casing of the present invention is different from the outer casing of a so-called soft shell battery equivalent to a bag such as that composed of a laminated film.

[0079] It is preferred that the metal exterior has a structure consisting of a single metal component. For example, the metal exterior may be a single component consisting of a metal such as stainless steel (SUS) or aluminum. The "single metal component" mentioned here refers in a broad sense to an exterior component that does not have a so-called laminated structure, and in a narrow sense to an exterior component that is substantially composed only of metal. Therefore, as long as it is a component that is substantially composed only of metal, appropriate surface treatment may be applied to the surface of the metal exterior component. For example, in a cross-section obtained by cutting such a metal exterior component along its thickness direction, a single metal layer can be identified in addition to the portion that has been subjected to surface treatment, etc.

[0080] Because it is a non-laminated structure, the metal exterior can have a relatively thin thickness. For example, the thickness of the metal exterior of the present invention can be greater than 50 μm and less than 200 μm, for example, greater than 50 μm and less than 190 μm, greater than 50 μm and less than 180 μm, or greater than 50 μm and less than 170 μm, etc. Such a thinner exterior contributes to the miniaturization of secondary batteries and the improvement of energy density. In the present invention, the phenomenon of adverse conditions caused by the "thinness" of the exterior is suppressed. This situation is described in detail. For the existing rivet-type external output terminal, as mentioned above, the region 95' of the insulating portion 90' present near the edge of the exterior 50' may be extremely thinned or disconnected due to the compressive force accompanying the "riveting" (refer to Fig.19 ). In particular, the thinner the thickness of the outer component 50' is, the more likely such an undesirable phenomenon will become apparent. This is because if the outer component 50' is thinner, there is a tendency for the stress that locally thins the region 95' of the insulating portion 90' and causes the stress that disconnects there to be more concentrated. In this regard, in the present invention, since it is a non-riveted structure, even if the thickness of the metal outer component is thinned, such an undesirable phenomenon will not occur. In other words, for the external output terminal of the present invention, it is possible to achieve miniaturization of the secondary battery and increase the energy density without compromising the required sealing force.

[0081] Alternatively, when the metal outer component is composed of a cup-shaped component and a cover-shaped component, the cup-shaped component and the cover-shaped component are joined to each other to form an airtight seal. In other words, the cup-shaped component and the cover-shaped component are not riveted, so an airtight seal based on riveting may not be performed. As a result, compared with a secondary battery having an outer component that is riveted, it is easy to achieve a space-saving secondary battery. In other words, the non-riveted form of the cup-shaped component and the cover-shaped component appropriately contributes to the miniaturization of the secondary battery and the improvement of the energy density.

[0082] In a preferred embodiment, the external output terminal is one of the positive and negative electrodes, and the external component is the other of the positive and negative electrodes. This can reduce the number of components of the secondary battery, and the space required for output in the thickness direction of the battery cell can be halved compared to the case where the terminal plates are provided on the upper and lower surfaces.

[0083] For example, the positive side of the secondary battery is only provided on the metal plate of the external output terminal, and on the other hand, the negative side of the secondary battery can also be provided in any area of ​​the exterior component. In other words, it is also possible that only the positive side uses the external output terminal of the metal plate, and the negative side can be externally connected from any place of the metal exterior component. If the side using the terminal plate (i.e., the metal plate) for output is used as the positive electrode in this way, the metal exterior component (i.e., the side that becomes the metal "can" as a whole) becomes the negative electrode. Therefore, a lithium-ion battery designed to have a larger negative electrode area than the positive electrode can reduce the possibility of causing a large short circuit even if it is assumed that the electrode is in contact with the inside of the can.

[0084] The present invention can be embodied in various forms, and this aspect will be described below.

[0085] (External output terminals located inside the exterior)

[0086] This method is a method in which the external output terminal is positioned inside the exterior member. Figure 6 As shown, in such a mode, the metal plate 62 is positioned inside the exterior member 50. When the insulating material 64 is arranged inside the exterior member 50, it can be said that the metal plate 62 is attached to the inside of the exterior member 50 via the insulating material 64. In such a mode, the metal plate is positioned inside the outer surface level of the exterior member, so that the secondary battery can have a shape in which the portion of the external output terminal is recessed.

[0087] When the external output terminal is positioned on the inner side of the outer member, the outer member does not protrude outward compared to the existing rivet-type output terminal, and the energy density of the battery is correspondingly easily increased. In addition, for the method of positioning the external output terminal on the inner side of the outer member, it is preferred that the connection part on the side of the external device connected to the secondary battery has a convex portion, which can help improve the design freedom of the secondary battery.

[0088] like Figure 7 As shown, in such a manner, a metal component 67 may also be provided on the outer side surface of the metal plate 62. This is because, in the secondary battery, the possibility of easier connection with external equipment becomes higher. The metal component 67 may also be directly provided on the metal plate 62. A pole ear extending from the electrode assembly may also be connected relative to the metal component 67. Such a metal component 67 may also be thicker than the metal plate 62. In addition, as shown in the figure, the outer surface of the metal component 67 may also be substantially at the same level as the outer surface of the outer component 50. By providing the metal component 67 in this way, it is possible to facilitate the connection with the external equipment in the external output terminal. The material of such a metal component 67 may also be the same as that of the metal plate 62, or it may be different from that of the metal plate 62.

[0089] (External output terminal located outside the exterior component)

[0090] This is the way in which the external output terminal is positioned relative to the outside of the exterior member. Figure 8 As shown, in such a method, the metal plate 62 is positioned outside the exterior member 50. When the insulating material 64 is provided outside the exterior member 50, it can be said that the metal plate 62 is attached to the outside of the exterior member 50 via the insulating material 64. In such a method, the metal plate is positioned outside the level of the outer surface of the exterior member, so that the portion of the secondary battery having the external output terminal is convexly raised.

[0091] When the external output terminal is positioned on the outside of the outer member, the outer member does not protrude inward compared to the existing rivet-type output terminal, and the electrode assembly can be set up relatively large accordingly. In other words, it is easy to improve the energy density of the battery. In addition, for the method in which the external output terminal is positioned on the outside of the outer member, it is preferred that the connection part on the side of the external device connected to the secondary battery has a recess, which can help improve the design freedom of the secondary battery.

[0092] like Fig. 9As shown, a metal component 67 may also be provided on the inner side of the metal plate 62. This is because it is highly likely that the connection with the internal terminal in the external output terminal becomes easier. The metal component 67 may also be directly provided on the metal plate 62. A pole ear extending from the electrode assembly may also be connected to the metal component 67. Such a metal component 67 may also be thicker than the metal plate 62. As shown in the figure, for example, the inner surface of the metal component 67 may also be substantially at the same level as the inner surface of the exterior component 50. By providing the metal component 67 in this way, it is possible to facilitate the connection with the internal terminal in the external output terminal. The material of the metal component 67 may also be the same as that of the metal plate 62, or it may be different from that of the metal plate 62.

[0093] The inventors of the present application have repeatedly conducted earnest studies on a secondary battery whose external output terminal is positioned on the outside, from the perspective that there is room for improving safety during use. As a result, it was found that by actively using the external output terminal as a ventilation component, a battery having a more preferred ventilation mechanism (hereinafter also referred to as a "ventilation function") can be obtained. Specifically, for the external output terminal located on the outside of the exterior component, the joint between the insulating material and the exterior component and / or the metal plate can be peeled off due to the rising internal pressure of the battery cell of the secondary battery. In such a case, when the internal pressure of the battery cell becomes excessively high due to the use of the battery such as charging and discharging, the metal plate 62 can be opened (see Fig.10 ), the external output terminal can be used as a degassing mechanism in abnormal situations. In other words, in this way, when the metal plate is joined to the outside of the outer member via the insulating material, when the internal pressure of the battery cell rises, the joint surface of the insulating material is peeled off first, which can reduce the internal pressure. In addition, when the battery temperature rises due to abnormal heating of the battery and heating from the outside, the insulating material melts and the joint surface is peeled off, and the pressure can be safely reduced before the internal pressure of the battery becomes excessively high. Therefore, such a secondary battery has the advantage of not requiring a vent as a battery design.

[0094] In order to effectively exert the ventilation function, the metal plate is preferably not fixed by any member other than the insulating material. In addition, as the electrode tab 70 for connecting the electrode assembly to the metal plate, i.e., the conductive electrode tab, it is preferably as follows Fig.10 As shown, the metal plate 62 can be opened.

[0095] The ventilation mechanism associated with the external output terminal is described in detail. If the internal pressure of the battery cell increases as the battery is used such as charging and discharging, the force borne by the metal plate 62 due to the internal pressure of the battery cell also increases. In a preferred embodiment of the present invention, when the internal pressure of the battery cell becomes higher than necessary, the force borne by the metal plate 62 exceeds the bonding force between the metal plate 62 and the exterior member 50 (in other words, the bonding force of the metal plate 62 to the exterior member 50 via the insulating material 64), and at least a portion of the metal plate 62 can be detached from the exterior member 50. For example, when the metal plate 62 is provided in a manner covering the opening portion 55 of the exterior member 50, the metal plate 62 can be displaced in a manner of opening the cover (refer to Fig.10 ). By opening the metal plate 62, the excess gas inside the exterior component is released to the outside of the exterior component, and more serious accidents such as undesirable battery explosion can be avoided.

[0096] In this specification, "battery cell internal pressure" refers to the pressure inside the external part of the secondary battery in a broad sense. In a narrow sense, "battery cell internal pressure" refers to the pressure inside the external part that has an electrode assembly and is in an airtight state (especially the internal pressure when the battery is in use). In addition, the "insulating material" of this embodiment contributes to the ventilation mechanism as described above, and can be referred to as an insulating material that can be peeled off when the internal pressure of the battery cell is abnormal, that is, an insulating material that can be peeled off.

[0097] In order to make the metal plate 62 open more appropriately in the ventilation mechanism, the tab 70 connected to the metal plate 62 may also have a "redundancy". In other words, if the length of the tab 70 connected to the metal plate 62 is not redundant, the existence of the tab itself becomes a resistance to the opening of the metal plate 62, and the metal plate 62 may not be opened smoothly in an abnormal situation. In this regard, it is also possible that, for the ventilation mechanism involved in the present invention, the length of the tab 70 between the electrode assembly 10 and the metal plate 62 is relatively long to a degree that does not inconveniently hinder the opening of the metal plate 62 (in particular, it can be longer than the existing tab length). In other words, the tab 15 can have a length that does not act between the metal plate 62 and the electrode assembly 10. Excessive tension that hinders the opening of the metal plate 62.

[0098] For example, for Figure 5 In the exemplary embodiment of (A) and (B) of FIG. 5 , the tab 70 extending from the electrode assembly 10 is provided on the metal plate 62 while being bent. Figure 5 As shown in the example modes of (A) and (B) of 5, the tab 70 may also have a curved shape such as bending (for example, it may also have a shape such as bending at the end of the tab). By having such a bent and / or curved tab 70, it is possible to prevent the opening of the metal plate 62 as a ventilation mechanism from being inconveniently hindered.

[0099] Alternatively, in the ventilation mechanism, the exterior member 50 may be displaced due to the rising internal pressure of the battery cell in order to open the metal plate 62 more appropriately. In other words, when the internal pressure of the battery cell becomes abnormally high, the exterior member 50 may be deformed in a twisting or bending manner, and the metal plate 62 may be easily detached from the exterior member 50. In this way, the exterior member is deformed in a twisting or bending manner, and the ventilation mechanism with the metal plate 62 opened may function more appropriately. For example, the exterior portion of the exterior member that provides the surface on which the metal plate is disposed may be at least partially displaced due to the rising internal pressure of the battery cell. Figure 5 (A) and Figure 5 In the example shown in (B), the exterior part 56 having the surface on which the metal plate 62 is arranged in the structural surface of the exterior member 50 may be deformed in a twisted or flexed manner, thereby making it easy for the metal plate 62 to detach from the exterior member 50. Figure 5 In (A), when the main surface 52A of the cup-shaped member 52 of the exterior member 50 is provided with the opening 55 and the metal plate 62 is disposed, the main surface 52A can be displaced by the increased internal pressure of the battery cell. Figure 5 In (B), when the cover-shaped member 54 of the exterior member 50 is provided with an opening 55 and a metal plate 62 is disposed, the cover-shaped member 54 can be displaced by the increased internal pressure of the battery cell. The cover-shaped member 54 alone becomes the "exterior portion 56 providing a surface on which the metal plate 62 is disposed", and therefore, it is easy to set it as a displaceable member.

[0100] (Thin-wall method for exterior parts)

[0101] Such an aspect is an aspect in which a part of the exterior member has a thin-walled shape. Specifically, the exterior member has a thin-walled shape in a portion of the structural surface of the exterior member that provides a surface on which the metal plate is disposed.

[0102] For example, Fig.11 As shown in the figure, the thickness of the exterior part 56 having the surface on which the metal plate 62 is arranged among the structural surfaces of the exterior member 50 is smaller than the thickness of the metal plate 62. In other words, the thickness of the exterior part 56 provided with the external output terminal 60 is smaller than the thickness of the metal plate 62. In such a form, in the event of an abnormality such as excessive increase in the internal pressure of the battery cell, the exterior part 56 is easily deformed in a twisted or flexed manner, and the metal plate 62 can be displaced in a manner of detaching from the exterior member 50. In other words, the ventilation mechanism with the metal plate 62 opened is easy to function more appropriately.

[0103] Alternatively, the exterior portion having a surface on which the metal plate is disposed may have lower rigidity than the metal plate. Conversely, the metal plate may have relatively higher rigidity than the exterior portion having a surface on which the metal plate is disposed. Such a difference in rigidity contributes to the realization of a more preferred ventilation mechanism. In the event of an abnormality such as excessive internal pressure in the battery cell, the metal plate is not easily deformed due to its high rigidity, while the exterior portion constituting the surface on which the metal plate is disposed can be deformed, so that the joint surface of the insulating material is easily peeled off and the metal plate 62 is easily opened.

[0104] Although it is just an example, the thickness of the outer casing 56, which is the surface on which the metal plate is arranged, may be 170 μm or less. If the thickness of such an outer casing is 170 μm or less, the outer casing is easily deformed in abnormal situations such as when the internal pressure of the battery cell becomes excessively high, and the metal plate 62 as a ventilation mechanism is easily opened. In other words, if the thickness of the outer casing is greater than 170 μm (for example, if the thickness is greater than 200 μm), the outer casing will not be deformed in abnormal situations, and it is difficult to cause the expected opening of the metal plate 62. The lower limit of the thickness of such a thin outer casing is not particularly limited, but may be 50 μm, for example.

[0105] In addition, it can also be, Figure 5 As in (A), when the main surface 52A of the cup-shaped member 52 of the exterior member 50 is provided with the opening 55 and the metal plate 62 is disposed, the main surface 52A is thinner than the thickness of the metal plate 62. On the other hand, it is also possible that Figure 5 As in (B), when the cover-like member 54 of the exterior member 50 is provided with the opening 55 and the metal plate 62 is disposed, the thickness of the cover-like member 54 is smaller than the thickness of the metal plate 62. The cover-like member 54 alone becomes the "exterior portion 56 providing the surface on which the metal plate 62 is disposed", and therefore, it is easy to be provided as a member with a small thickness, and therefore, it is easy to be a member that is easily deformed in a twisted or flexed manner.

[0106] (Special insulation material structure)

[0107] In such a method, the insulating material has a special structure. Specifically, the insulating material is composed of at least two materials having different melting points.

[0108] The insulating material may be, for example, a thermoplastic resin, or may have a laminated structure in which a low-melting-point resin layer having a relatively low melting point and a high-melting-point resin layer having a relatively high melting point are laminated on each other. If resin layers having different melting points are provided in the insulating material, not only the manufacturing process of the battery is more preferred, but also the use of the battery is more preferred. During the manufacturing process, the handling of the insulating material can be ensured by the high-melting-point resin layer, and the metal plate and the exterior component can be joined at a lower temperature by the low-melting-point resin layer. On the other hand, when the battery is in use, in the event of an abnormality such as an excessive rise in the battery cell temperature, the relatively low melting point resin layer can be melted because of such a rise in the battery cell temperature. Therefore, when the battery cell is abnormal, the joint surface of the insulating material is easy to peel off, and the metal plate 62 is easier to open properly.

[0109] For example, the insulating material may have a structure in which a double layer of low melting point resin layer is laminated via a high melting point resin layer. Fig.12 As shown, the insulating material 64 may also have a structure (i.e., a three-layer structure as shown in the figure): the structure has a high melting point resin layer 65 with a relatively high melting point and a low melting point resin layer 66 with a relatively low melting point sandwiching the high melting point resin layer. In such a case, the joint surface between the metal plate 62 and the insulating material 64 and the joint surface between the exterior member 50 and the insulating material 64 become interfaces directly involved in the low melting point resin layer. Therefore, in the event of an abnormality such as excessive temperature rise of the battery cell, the melting of the low melting point resin layer is likely to occur directly at the interface, and the peeling of the joint surface is likely to occur, and the metal plate 62 is likely to be opened more appropriately.

[0110] The low melting point resin layer has a relatively lower melting point than the high melting point resin layer. On the other hand, the high melting point resin layer has a relatively higher melting point than the low melting point resin layer. For example, if the abnormal battery cell temperature is set to T°C, the low melting point resin layer may also have a melting point lower than the abnormal battery cell temperature T°C, and the high melting point resin layer may also have a melting point higher than the abnormal battery cell temperature T°C. Although this is only an example, the abnormal battery cell temperature T°C is, for example, about 150°C to 200°C.

[0111] The low melting point resin layer and the high melting point resin layer can be composed of different molecules (e.g., different monomer units). Alternatively, the low melting point resin layer and the high melting point resin layer can also be based on the same molecule (e.g., the same or the same monomer unit) structure. For example, the low melting point resin layer and the high melting point resin layer can also contain the same olefin as a monomer constituent element. In this case, the physical properties of the low melting point resin layer and the high melting point resin layer, especially the melting point, are different. Therefore, the polymerization degree and the proportion of the amorphous part can also be different between the material of the low melting point resin layer and the material of the high melting point resin layer. As the same olefin, for example, ethylene or propylene can be used. Although not limited by a specific theory, if the polymerization degree is relatively high, and / or the proportion of the amorphous part is relatively small (e.g., if the crystallinity is relatively high), the material of the resin layer is easy to have a relatively high melting point. Such a degree of polymerization and crystallinity can also be adjusted using conventional methods, for example, by changing the reaction temperature, pressure and / or catalyst in the polymerization reaction. In addition, it is not limited to homopolymers, and the materials of both the low-melting point resin layer and the high-melting point resin layer may be copolymers or terpolymers containing the same olefin as a monomer unit. In such a case, as the main monomer, the same olefin may contain, for example, 50 mol% or more (based on 100 mol% of all monomers), and the content of the comonomer (the comonomer may be an olefin or may not be an olefin. In addition, by making the comonomer itself the same or the same between the low-melting point resin layer and the high-melting point resin layer) is increased, the material of the resin layer tends to have a relatively low melting point. Regardless of whether it is such a homopolymer, copolymer or terpolymer, commercially available resin materials with different melting points can be used as the resin materials of the low-melting point resin layer and the high-melting point resin layer.

[0112] Such an insulating material composed of resin layers with different melting points may also have a film form. For example, the insulating material may be composed of a multilayer film in which two low-melting-point resin layers are laminated via a high-melting-point resin layer.

[0113] (Surface treatment method)

[0114] Such a method is a method in which a surface treatment is applied to a surface for bonding with an insulating material. Specifically, a bonding surface of an exterior member and / or a bonding surface of a metal plate bonded with an insulating material is a surface treated surface.

[0115] For example Figure 2As shown, the surface 50A of the surface of the exterior component 50 that is bonded to the insulating material 64 (hereinafter, also referred to as the "exterior component bonding surface") may also be a surface that has been at least surface-treated. Similarly, the surface 62A of the surface of the metal plate 62 that is bonded to the insulating material 64 (hereinafter, also referred to as the "metal plate bonding surface") may also be a surface that has been at least surface-treated. The exterior component bonding surface and / or the metal plate bonding surface become surface-treated surfaces, so that the bonding state of the metal plate relative to the exterior component can be more preferred. Therefore, the ventilation mechanism of the present invention is more likely to function as expected. In other words, it is possible to suppress the phenomenon of adverse conditions such as the metal plate 62 opening in non-abnormal conditions when the internal pressure of the battery cell or the temperature of the battery cell is not excessively high, and it is easy to become a secondary battery in which the metal plate 62 opens in abnormal conditions as originally assumed.

[0116] The surface treatment may also be a treatment to improve the bonding properties, for example, it may also be a treatment to improve the bonding strength between the exterior component and the insulating material and / or the bonding strength between the metal plate and the insulating material. More specifically, the above-mentioned bonding surface may also be subjected to chemical treatment based on cleaning, grinding and / or chemical reagents, physical treatment based on plasma and / or ultraviolet rays, primer treatment to impart a metal compound layer, and plating treatment. In other words, the exterior component bonding surface and / or the metal plate bonding surface may also be a surface selected from at least one of the group consisting of a cleaning treatment surface, a grinding treatment surface, a chemical reagent treatment surface, a plasma treatment surface, an ultraviolet treatment surface, a primer treatment surface, and a plating treatment surface. Thus, the ventilation mechanism is more likely to function as expected.

[0117] In a preferred embodiment, the exterior member joint surface and / or the metal plate joint surface is a primer-treated surface. In such a case, the insulating material and the exterior member are joined to each other via the primer-treated surface, or the insulating material and the metal plate are joined to each other via the primer-treated surface. The primer treatment method is only a specific example, but it can also include a treatment such as chromate treatment to apply a metal oxide film.

[0118] (Special thickness method for insulating materials)

[0119] Such a method is a method in which the thickness of the insulating material has a special thickness shape. Specifically, the insulating material has a non-uniform thickness.

[0120] like Fig.13As shown, the insulating material 64, for example, may be in a relatively thin-walled form at a portion sandwiched between the metal plate 62 and the exterior member 50. In other words, the insulating material 64 may not be of a constant thickness as a whole, but may be in a form having a thin-walled portion 64a with a relatively small thickness and a thick-walled portion 64b with a relatively large thickness. In particular, the metal plate 62 may be in a form that sinks toward the exterior member 50 in the thin-walled portion 64a of the insulating material 64, and may be in a form that thick-walled portions 64b exist on both sides or one side of the thin-walled portion 64a. In such a manner, it is easy to form an external output terminal that is more preferred in terms of airtight sealing. In addition, in view of such an insulating material, it can be said that the insulating material in the present invention may be slightly embossed or bent without being riveted.

[0121] (Top view of a circular secondary battery)

[0122] In such an embodiment, the secondary battery has a circular shape when viewed from above. In other words, the secondary battery has a button-shaped or coin-shaped outer shape.

[0123] The circular shape of the secondary battery in plan view means that the shape of the electrode assembly or the outer casing containing the electrode assembly when the electrode assembly is viewed from the top or bottom along the stacking direction of the positive electrode and the negative electrode is substantially circular.

[0124] The "circle (roughly circular shape)" mentioned here is not limited to a perfect circle (i.e., just a "circle" or a "perfect circle"), but also includes shapes derived from the perfect circle and generally included in the "circular shape" in the understanding of those skilled in the art. For example, it is not only a circle or a perfect circle, but also a shape whose arc curvature is locally different, and further, it can be a shape derived from a circle or a perfect circle, such as an ellipse. As a typical example, such a circular battery in top view is equivalent to a so-called button-type or coin-type battery.

[0125] In the present invention, in the secondary battery having a substantially circular shape when viewed from above, the outer casing does not have a "riveted" form. In other words, the terminal area of ​​the external connection terminal and / or the joining area between the cup-shaped component and the lid-shaped component of the outer casing do not include a riveted structure. The riveted structure increases the volume accordingly, but in the method of the present invention, there is no riveted structure, so it is easy to become a secondary battery preferred in terms of miniaturization and improved energy density.

[0126] (Change of terminal position)

[0127] This method is a method in which the configuration of the external output terminal is changed. Fig.14 As shown in (A) to (C) of FIG. 1 , in the present invention, the configuration of the external output terminal 60 of the exterior member 50 can take various forms. Specifically, in Fig.14In (A), the external output terminal 60 is arranged on the upper surface or top surface of the exterior member 50. Fig.14 In (B), the external output terminal 60 is arranged on the side of the exterior member 50. Fig.14 In (C), the external output terminal 60 is arranged on the lower surface or bottom surface of the exterior member 50. Fig.14 When the shape of the exterior member 50 of (B) is a cylinder, the metal plate 62 is joined with a curvature so as to follow the circular shape of the side surface of the exterior member 50. Such a change in the arrangement of the external output terminal can contribute to an improvement in the degree of freedom in the design of the secondary battery.

[0128] Finally, the method for forming the external output terminal is described. In the embodiment involved in the present invention, the method for forming the external output terminal is not particularly limited, and any method may be used. For example, in the case of using a structure composed of a thermoplastic resin as an insulating material, after a metal plate is arranged around a hole provided in an exterior component via an insulating material, a heat treatment is performed, thereby forming an external output terminal. The insulating material is temporarily melted during the heat treatment, thereby allowing the metal plate to be attached to the exterior component via the insulating material. In addition, it is also possible to apply the molten insulating material to the exterior component in advance, and to arrange the metal plate on the applied insulating material, thereby forming the external output terminal.

[0129] In the external output terminal, the metal plate and the tab are connected to each other, but they may be connected by laser welding or the like, for example. Fig.10 ) When the tab 70 is connected to the metal plate 62 by welding via the metal block 67, the laser welding process can be more easily performed. In addition, since the tab 70 is laser-welded via the metal block 67, it is possible to achieve deeper melting and more enhanced connection than when laser welding is directly performed on the metal plate 62. Moreover, during laser welding, the metal block functions as a heat sink, and it can be expected that the influence of heat accompanying laser welding is less likely to affect the insulating material.

[0130] The embodiments of the present invention have been described above, but these are only typical examples, and therefore, the present invention is not limited thereto, and it is easily understood by those skilled in the art that various embodiments can be adopted.

[0131] For example, in the above, the secondary battery mainly involves a button type / coin type, but the present invention is not necessarily limited to this. For example, it can also be a square secondary battery. In other words, Fig.15As shown in (a) to (d) of FIG. 1 , the top view shape of the secondary battery 100 is not limited to a circle, but may also have a quadrilateral, rectangular, or other shape. Similarly, the shape of the external output terminal 60, that is, the shape of the metal plate 62 (especially the top view shape) is not necessarily limited to a circle, but may also have a quadrilateral, rectangular, or other shape (see FIG. 1 ). Fig.16 (a)~(d)).

[0132] In addition, in the above description, the insulating material 64 is provided on the exterior member 50 so as to protrude outward from the metal plate 62 ( Figure 2 (A) and Figure 2 (B)), but the present invention is not necessarily limited to this. It is also possible to set the insulating material 64 to be shielded below the metal plate 62 instead of extending outward from the metal plate 62. For example, the insulating material 64 may be provided only at a position substantially the same as the outer edge of the metal plate 62 or at a position closer to the inner side than the outer edge.

[0133] Furthermore, in the above description, the structure in which the outer casing is composed of a single metal component is mainly described, but an additional layer may be provided locally with respect to the single metal component. For example, a resin layer for insulation may be provided at a portion of the outer casing other than the joint surface with the insulating material. This is because it is easier to suppress the phenomenon of adverse conditions such as short circuits. For example, in Fig.17 In the illustrated form, a resin layer (not shown) may be provided relative to the inner side surface 56' of the exterior member portion 56 having the opening 55 of the exterior member 50, the outer side surface 56 of the exterior member portion 56 (particularly, the surface area close to the outer peripheral side where the insulating material 64 is not provided) and / or the end surface 55a forming the exterior member opening. In addition, these resin layers are provided partially or locally relative to the exterior member, which is different from the case where a laminate film is formed as the exterior member.

[0134] Furthermore, the drawings (such as Figure 2 (A) and Figure 2 In (B)), the thickness of the insulating material 64 is relatively large and is shown to be the same as the thickness of the metal plate 62, but the present invention is not necessarily limited to this. Fig.18 As shown, the thickness of the insulating material 64 may be smaller than the thickness of the metal plate 62. In addition, the thickness of the insulating material 64 may be equal to or smaller than the thickness of the "exterior portion 56 providing the surface on which the metal plate 62 is disposed".

[0135] Furthermore, in the above-mentioned "special insulating material structure method", the resin layers with different melting points are described, but the "melting point" mentioned in this method mainly refers to the melting point in the case of crystalline resin (including the case where the degree of crystallization is not 100%). There may also be a case where a non-crystalline resin or a resin with a higher proportion of non-crystalline resin has no melting point or does not show a clear melting point, but in such a case, the "melting point" can be replaced with the "glass transition point" to understand this method.

[0136] and, Fig.10 Although a ventilation mechanism is shown in FIG. 1 , the present invention is not necessarily limited to the illustrated embodiment. Fig.10 In the embodiment, for example, the tab 70 is attached to the metal plate 62 via the metal member 67 . However, the tab 70 may be directly attached to the metal plate 62 without using the metal member 67 .

[0137] Industrial Availability

[0138] The secondary battery involved in the present invention can be used in various fields where electricity storage is assumed. Although it is only an example, the secondary battery of the present invention can be applied to the following fields: electrical / information / communication fields using electrical / electronic equipment, etc. (for example, including mobile phones, smart phones, notebook personal computers and digital cameras, activity meters, ARM computers, electronic paper, wearable devices, RFID tags, card-type electronic money, smart watches and other small electronic machines, etc., electrical / electronic equipment fields or mobile device fields); household / small industrial uses (for example, power tools, golf carts, household / nursing / industrial robots); large industrial uses (for example, forklifts, elevators, port cranes); transportation system fields (for example, hybrid vehicles, electric vehicles, buses, trams, electric bicycles, electric motorcycles and other fields); power system uses (for example, various power generation, load regulators, smart grids, general household installation type power storage systems and other fields); medical uses (medical equipment fields such as earphones and hearing aids); medical uses (medical management systems and other fields); and IoT fields; space / deep sea uses (for example, space probes, submersible survey ships and other fields).

[0139] Description of Reference Numerals

[0140] 1: positive electrode; 2: negative electrode; 3: separator; 5: electrode structure layer; 10: electrode assembly; 50: outer casing; 50A: surface of outer casing joined to insulating material; 55: opening; 55a: edge portion forming the opening; 52: cup-shaped component; 54: lid-shaped component; 56: outer casing portion having a surface with a metal plate; 56': inner side surface of the outer casing portion provided with the opening; 56": outer side surface of the outer casing portion provided with the opening; 60: external output terminal; 62: metal plate; 62A: surface of the metal plate joined to insulating material; 64: insulating material; 64a: thin-walled portion of insulating material; 64b: thick-walled portion of insulating material; 67: metal component; 70: pole ear; 100: secondary battery.

Claims

1. A secondary battery comprising an electrode assembly and an exterior member for housing the electrode assembly, wherein: The exterior member includes a metal plate joined via an insulating material, the metal plate being an external output terminal. The external output terminal is provided by attaching the metal plate to the exterior member via the insulating material, so that the external output terminal has a non-riveted structure. The metal plate is attached to the outer side of the exterior member via the insulating material, and the insulating material is located on the outer side of the exterior member and extends on the same plane. The insulating material is capable of being peeled off at a joint portion with respect to the exterior member and / or the metal plate due to an increase in the internal pressure of the battery cell of the secondary battery. The electrode assembly and the metal plate are connected in a bent or curved state by a flexible conductive electrode lug. The insulating material is composed of at least two materials with different melting points. The insulating material has a structure including a high melting point resin layer having a relatively high melting point and a low melting point resin layer having a relatively low melting point sandwiching the high melting point resin layer.

2. The secondary battery according to claim 1, wherein The exterior member is a metal exterior member having a two-part structure of a cup-shaped member and a lid-shaped member.

3. The secondary battery according to claim 1 or 2, wherein: The external output terminal is one of a positive electrode and a negative electrode, and the exterior member is the other of the positive electrode and the negative electrode.

4. The secondary battery according to claim 1, wherein A metal component is also arranged on the inner side of the metal plate.

5. The secondary battery according to claim 1, wherein An exterior portion of the exterior member that provides a surface on which the metal plate is disposed can be at least partially displaced by the increased battery cell internal pressure.

6. The secondary battery according to claim 1 or 2, wherein: The thickness of the exterior portion of the exterior member that provides a surface on which the metal plate is disposed is smaller than the thickness of the metal plate.

7. The secondary battery according to claim 1 or 2, wherein: The joining surface of the exterior member and / or the joining surface of the metal plate joined to the insulating material is a surface-treated surface.

8. The secondary battery according to claim 1 or 2, wherein: The metal plate follows the shape of the exterior member.

9. The secondary battery according to claim 1 or 2, wherein: The insulating material is formed in a shape along the outer shape of the exterior member.

10. The secondary battery according to claim 1 or 2, wherein: The exterior member is provided with an opening, and the metal plate is disposed on a surface of the exterior member located around the opening with the insulating material interposed therebetween.

11. The secondary battery according to claim 1 or 2, wherein: The electrodes of the electrode assembly include a positive electrode and a negative electrode capable of occluding and releasing lithium ions.

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