Secondary battery

Abstract

Provided is a secondary battery having an electrode assembly and an exterior body that houses the electrode assembly. In the secondary battery, a flat plate-shaped terminal that is joined across an insulating member is provided on the exterior body, the flat plate-shaped terminal is composed of a first terminal member and a second terminal member, the first terminal member and the second terminal member are formed of materials having different linear expansion coefficients, the first terminal member and the second terminal member are laminated to each other with the first terminal member laminated on the second terminal member, and the flat plate-shaped terminal is disposed on the insulating member with the second terminal member facing the insulating member.

Description

Technical Field

[0001] This invention relates to secondary batteries. Specifically, this invention relates to secondary batteries including an electrode assembly, the electrode assembly being formed of an electrode constituting layer including a positive electrode, a negative electrode, and a separator. Background Technology

[0002] Secondary batteries, also known as rechargeable batteries, can be repeatedly charged and discharged, and are used for a wide variety of purposes. For example, they are used in mobile devices such as mobile phones, smartphones, and laptops.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-46639

[0006] Patent Document 2: Japanese Patent Application Publication No. 2020-47536 Summary of the Invention

[0007] The technical problem that the invention aims to solve

[0008] The inventors of this application have noticed technical problems that need to be overcome in conventional secondary batteries and have found it necessary to take measures to address them. Specifically, the inventors of this application have discovered the following technical problems.

[0009] For example, Patent Document 1 discloses a sealed battery with a closed structure. For example, such as... Figure 14 As shown, in conventional sealed batteries 100, for example, an electrode assembly 111 (see reference) is formed by stacking or winding the positive and negative electrodes with a separator in between. Figure 10 It is housed within the outer casing 104. The flat electrode terminal component 101 is bonded to the surface of the outer casing 104 via an insulating and adhesive sealing component 103, in a manner that covers the opening of the outer casing 104. For example, in Figure 14 In the battery 100 shown, the battery's sealing performance is ensured by using such a closed structure of a flat electrode terminal component 101 and a sealing component 103. Here, the larger the area where the flat electrode terminal component 101 and the sealing component 103 are bonded, the better the battery's sealing performance.

[0010] exist Figure 14 In the battery 100 shown, the flat electrode terminal component 101 and the electrode assembly 111 are electrically connected via leads or the like, but for ease of explanation, Figure 14 The description of the lead wire is omitted.

[0011] exist Figure 14In the conventional battery 100 shown, the sealing performance of the battery is improved by using a closed structure of a flat electrode terminal component 101 and a sealing component 103 (see reference). Figure 14 (A)).

[0012] However, on the other hand, the temperature rise and heat generated by abnormal charging and discharging can cause gas to be generated inside the battery. For example, by pressing the flat electrode terminal component 101 with force (F0) along the arrow, the pressure inside the battery increases, which may result in the battery rupturing and being damaged (see reference). Figure 14 (B) Therefore, in such batteries, not only is it required to ensure sealing, but also to ensure higher safety.

[0013] To ensure higher safety, for example, Patent Document 2 discloses a sealed battery equipped with an explosion-proof valve, etc. For example, such as Figure 15 As shown, the electrode assembly 211, formed by winding the positive and negative electrodes with a diaphragm in between (see reference) Figure 10 (B) is housed in the battery canister 204, and a sealing plate 205 is provided to block the opening of the battery canister 204. The external terminal 201 is fixed to the sealing plate 205 via an insulating gasket 203 and washer 202. In other words, the sealing plate 205 has an external terminal 201 provided using a riveting structure. Furthermore, two grooves, a first groove 206 and a second groove 207, are provided on the sealing plate 205 in an opposing manner, and a thin-walled portion is formed where the thickness of the sealing plate 205 locally decreases. When the internal pressure of the battery increases, the thin-walled portion of the sealing plate 205 breaks, and the sealing plate 205 functions as an explosion-proof valve, reducing the internal pressure of the battery.

[0014] For example in Figure 15 In the conventional battery 200 shown, the external terminal 201 and the electrode assembly 211 are electrically connected via leads or the like, but for ease of explanation, Figure 15 The description of the lead wire is omitted.

[0015] exist Figure 15 In the conventional battery 200 shown, an explosion-proof valve can suppress the increase in internal pressure. However, the structure of such an explosion-proof valve is complex, thus increasing its manufacturing cost. Furthermore, in this battery 200 utilizing an explosion-proof valve, since a first groove 206 and a second groove 207 must be provided in the sealing plate 205, the design freedom is reduced as the area for securing such grooves is limited. Moreover, in... Figure 15 In the conventional battery 200 shown, the external terminal 201 encroaches on the space where the electrode assembly 211 is arranged, thereby reducing the volumetric energy density of the battery. In addition, ineffective space is generated inside the battery.

[0016] Therefore, the inventors of this application, for example in Figure 14 In a conventional battery 100 as shown, when the internal pressure of the battery increases due to abnormal heating, the pressure was reduced by cracking the seal. More specifically, the method of cracking the seal by peeling the flat electrode terminal component 101 from the sealing component 103 was studied.

[0017] Research has shown that when the internal pressure of the battery increases due to an abnormal temperature rise, it is preferable to use a lower pressure to detach the flat electrode terminal component 101 from the sealing component 103. However, it is also known that to improve the battery's sealing performance, the bonding area between the flat electrode terminal component 101 and the sealing component 103 must be increased to ensure sealing. In other words, it is known that ensuring the battery's sealing performance and causing the sealing portion to crack are inversely related. Thus, through the research of the inventors of this application, it has been clarified for the first time that it is difficult to ensure the battery's sealing performance while simultaneously causing the sealing portion to crack with a lower pressure when the internal pressure increases due to an abnormal temperature rise.

[0018] This invention was made in view of the following technical problem. That is, the main objective of this invention is to provide a secondary battery that ensures airtightness while allowing the sealing portion to crack under lower pressure in the event that the internal pressure increases due to abnormal temperature rise.

[0019] Technical solutions for solving technical problems

[0020] The inventors did not address the problem by extending existing technology, but rather by taking measures in a new direction to try to solve the aforementioned technical problems. As a result, an invention of a secondary battery that achieves the aforementioned main objectives was obtained.

[0021] Specifically, the following configuration is considered: In a closed portion formed by the outer casing of a secondary battery, flat terminals, and insulating components, the flat terminals are formed from at least two materials with different coefficients of linear expansion, thereby enabling the flat terminals to deform and warp during abnormal temperature rises in the battery (more specifically, see...). Figures 1 to 5 ,in particular Figure 2 (B) and Figure 4 (B)). It is believed that with this configuration, the battery's sealing can be ensured within the normal temperature range, and that in the event of abnormal temperature rise, the flat terminals can be at least partially detached from the insulating components by warping them (see reference). Figure 2 (B) and Figure 4 (B)) By peeling in this way, the sealing part can be cracked with lower pressure, thereby reducing the pressure inside the battery.

[0022] The present invention provides a secondary battery having an electrode assembly and an outer casing for housing the electrode assembly. In this secondary battery, the outer casing has a flat plate terminal joined with an insulating member in between. The flat plate terminal comprises a first terminal component and a second terminal component, the first terminal component and the second terminal component being formed of materials having different coefficients of linear expansion. The first terminal component and the second terminal component are stacked on top of each other such that the first terminal component is stacked on top of the second terminal component. The flat plate terminal is disposed on the insulating member such that the second terminal component is opposite to the insulating member.

[0023] Invention Effects

[0024] In this invention, a secondary battery can be obtained that ensures airtightness while allowing the sealed portion to crack under lower pressure even when the internal pressure increases due to abnormal heating. It should be noted that the effects described in this specification are merely examples and are not limited thereto; additional effects may also be possible. Attached Figure Description

[0025] Figure 1 This is a schematic diagram showing a cross-section of a secondary battery according to one embodiment of the present disclosure.

[0026] Figure 2 This is a schematic diagram illustrating the structure of the enclosure of a secondary battery according to one embodiment of the present disclosure.

[0027] Figure 3 This is a schematic diagram illustrating the warping of the flat terminal of a secondary battery according to one embodiment of the present disclosure.

[0028] Figure 4 This is a schematic diagram illustrating the structure of the enclosure of a secondary battery according to another embodiment of this disclosure.

[0029] Figure 5 This is a schematic diagram illustrating the warping of the flat terminals of a secondary battery according to another embodiment of this disclosure.

[0030] Figure 6 This is a schematic diagram illustrating the structure of the enclosure of a secondary battery according to another embodiment of the present disclosure.

[0031] Figure 7 This is a schematic diagram illustrating the structure of the enclosure of a secondary battery according to another embodiment of the present disclosure.

[0032] Figure 8 This is a schematic diagram showing a partially enlarged view of the structure of the enclosure of a secondary battery according to another embodiment of the present disclosure.

[0033] Figure 9 This is a simplified diagram schematically showing a partial enlargement of the warping of the flat terminal of a secondary battery according to another embodiment of the present disclosure.

[0034] Figure 10 It is a cross-sectional view schematically showing the configuration of the electrode assembly.

[0035] Figure 11 This is a three-dimensional schematic diagram used to illustrate (a) button-shaped or coin-shaped and (b) square-shaped secondary batteries.

[0036] Figure 12 The simulation results show the warping of the flat terminal when heated.

[0037] Figure 13 It is a graph showing the relationship between "bonded area" and "cracking pressure".

[0038] Figure 14 It is a schematic diagram illustrating a conventional battery.

[0039] Figure 15 It is a schematic diagram illustrating another conventional battery. Detailed Implementation

[0040] This disclosure relates to secondary batteries, and more specifically, to secondary batteries comprising an electrode assembly and an outer casing capable of housing the electrode assembly. In the secondary battery of this disclosure, the outer casing may have a flat plate terminal joined with an insulating member as a barrier. The flat plate terminal comprises a first terminal component and a second terminal component. The first terminal component and the second terminal component are formed of materials having different coefficients of linear expansion. The first terminal component and the second terminal component are stacked on top of each other such that the first terminal component is stacked on top of the second terminal component. The flat plate terminal is disposed on the insulating member such that the second terminal component faces the insulating member.

[0041] In this disclosure, the aforementioned secondary battery is sometimes referred to as "the secondary battery of this disclosure" or "the battery of this disclosure", or simply omitted as "secondary battery" or "battery".

[0042] For example, such as Figure 1 As shown, in a secondary battery 10 according to one embodiment of this disclosure, a flat terminal 5 comprising a first terminal component 1 and a second terminal component 2 is bonded or adhered to an outer casing 4 via an insulating component 3. As detailed below, the insulating component 3 may have insulating and adhesive or weldable properties. The outer casing 4 may be a conductive metal outer casing.

[0043] The flat terminal 5 may include a first terminal component 1 and a second terminal component 2, both of which may be conductive so that the flat terminal 5 functions as an electrode terminal. Both the first terminal component 1 and the second terminal component 2 may be made of materials including metals and / or alloys. Both the first terminal component 1 and the second terminal component 2 may have a plate-like shape.

[0044] The first terminal component 1 and the second terminal component 2 are formed of materials having different coefficients of linear expansion. By stacking the first terminal component 1 and the second terminal component 2, which have different coefficients of linear expansion, the first terminal component 1 and the second terminal component 2 are thus joined together, for example, by means of joining or other methods (see reference). Figure 2 (A) and Figure 4 (A) thus, for example, when the battery overheats abnormally, the flat terminal 5 can deform and "warp" (see reference). Figure 2 (B) and Figure 4 (B)

[0045] Through the warping of the flat terminal 5 during such heating, for example, Figure 2 As shown in (B), the flat terminal 5, particularly the second terminal component 2, can be at least partially peeled off from the insulating component 3. By partially peeling the flat terminal 5 off from the insulating component 3 in this way, the seal can be cracked with lower pressure.

[0046] Furthermore, within the normal temperature range, such as room temperature or ambient temperature, more adequate sealing can be ensured. Thus, according to the battery of this disclosure, sealing can be ensured while the seal can be broken at a lower pressure in the event of an abnormal increase in internal pressure due to temperature rise.

[0047] In the battery disclosed herein, since flat terminals are arranged on the outer surface of the outer casing, the internal space of the battery can be effectively utilized. Furthermore, the volumetric energy density of the battery can be increased. Additionally, since the battery disclosed herein does not use riveting structures, battery manufacturing costs can be reduced.

[0048] The following describes a secondary battery according to an embodiment of the present invention in more detail. Although the description is made with reference to the accompanying drawings as needed, the various elements in the drawings are shown schematically and illustratively only for the purpose of understanding the present invention, and the appearance and / or size ratio, etc., may differ from the actual object.

[0049] The "sectional view" described directly or indirectly in this specification is, for example, based on a virtual cross-section obtained by arbitrarily cutting a secondary battery. Similarly, for example, in the case of a "plate-shaped secondary battery with thickness" such as a button or coin shape, the direction of the "thickness" described directly or indirectly in this specification corresponds to the plate thickness direction of such a secondary battery. The "top view" or "top view shape" used in this specification is based on a schematic diagram when viewing the object from above or below along the direction of such thickness.

[0050] Furthermore, the terms "up and down" and "left and right" used directly or indirectly in this specification can be equated to the up and down and left and right directions in the figures, respectively. Unless otherwise specified, the same reference numerals or symbols denote the same parts and / or locations or have the same meaning. In a suitable manner, it can be understood that the vertical downward direction (i.e., the direction of gravity) is equivalent to the "downward direction," and its opposite direction is equivalent to the "upward direction."

[0051] The following section describes the basic structure of the battery and then details the features of the battery disclosed herein.

[0052] [Basic Components of a Battery]

[0053] The term "secondary battery" as used in this specification refers to a battery capable of repeated charging and discharging. Therefore, the term "secondary battery" in this disclosure is not overly limited to its name; for example, energy storage devices may also be included in the scope of the subject matter.

[0054] The secondary battery disclosed herein comprises an electrode assembly, which is obtained by stacking at least one electrode constituting layer including a positive electrode (or positive electrode body), a negative electrode (or negative electrode body), and a separator. For example, in Figure 10 (A) and Figure 10 (B) schematically illustrates a typical electrode assembly 11 that can be used in this disclosure. As shown, a positive electrode 12 and a negative electrode 14 are stacked with a separator 13 in between to form an electrode constituting layer 15. At least one or more electrode constituting layers 15 are stacked to form the electrode assembly 11. Figure 10 In (A), there is a planar stacked structure in which the electrode constituting layer 15 is stacked in a planar manner. On the other hand, in Figure 10 In (B), there is a wound-layered structure in which the electrode constituting layer 15 is wound into a spiral shape. That is to say, in Figure 10In (B), an electrode assembly 15 comprising a positive electrode, a negative electrode, and a separator disposed between the positive and negative electrodes is wound into a roll-shaped stacked structure. In the secondary battery of this disclosure, such an electrode assembly is encapsulated together with an electrolyte (e.g., a non-aqueous electrolyte) in an outer casing. It should be noted that the structure of the electrode assembly is not necessarily limited to a planar stacked structure or a wound stacked structure. For example, the electrode assembly may also have a so-called stack-folded structure obtained by stacking the positive electrode, separator, and negative electrode on a long thin film and then folding it.

[0055] The positive electrode comprises at least a positive electrode material layer and a positive electrode current collector as needed. In the positive electrode, for example, a positive electrode material layer is provided on at least one side of the positive electrode current collector. The positive electrode material layer contains a positive electrode active material as the electrode active material. For example, multiple positive electrodes in the electrode assembly may each have a positive electrode material layer provided on both sides of the positive electrode current collector, or a positive electrode material layer may be provided only on one side of the positive electrode current collector.

[0056] The negative electrode comprises at least a negative electrode material layer and a negative electrode current collector as needed. In the negative electrode, for example, a negative electrode material layer is provided on at least one side of the negative electrode current collector. The negative electrode material layer contains a negative electrode active material as an electrode active material. For example, multiple negative electrodes in the electrode assembly may each have a negative electrode material layer provided on both sides of the negative electrode current collector, or a negative electrode material layer may be provided only on one side of the negative electrode current collector.

[0057] Electrode active materials, namely positive and negative electrode active materials, which can be contained in the positive and negative electrodes, are substances that can directly participate in electron donation and acceptance in a secondary battery. They are the main substances of the positive and negative electrodes that bear the responsibility of charging and discharging, i.e., the battery reaction. More specifically, due to the "positive active materials that can be contained in the positive electrode material layer" and the "negative active materials that can be contained in the negative electrode material layer," ions are introduced into the electrolyte. These ions move between the positive and negative electrodes to carry out electron donation and acceptance, thus enabling charging and discharging. The positive and negative electrode material layers can be layers capable of inserting and deintercalating lithium ions. That is, the secondary battery of this disclosure can be a non-aqueous electrolyte secondary battery in which lithium ions move between the positive and negative electrodes via a non-aqueous electrolyte, enabling the battery to be charged and discharged. When lithium ions participate in charging and discharging, the secondary battery of this invention is equivalent to a so-called "lithium-ion battery," with the positive and negative electrodes having layers capable of inserting and deintercalating lithium ions.

[0058] When the positive electrode active material in the positive electrode layer can be composed of granules, a binder can be included in the positive electrode material layer to ensure more sufficient contact between the particles and to maintain their shape. Furthermore, a conductive additive can be included in the positive electrode material layer to facilitate the transfer of electrons that promote the battery reaction. Similarly, when the negative electrode active material in the negative electrode layer can be composed of granules, a binder can be included in the negative electrode material layer to ensure more sufficient contact between the particles and to maintain their shape. Furthermore, a conductive additive can be included in the negative electrode material layer to facilitate the transfer of electrons that promote the battery reaction.

[0059] Thus, since it is a form containing multiple components, the positive electrode material layer and the negative electrode material layer can also be called "positive electrode mixed material layer" and "negative electrode mixed material layer", respectively.

[0060] The positive electrode active material can be a substance that facilitates the insertion and extraction of lithium ions. In this sense, the positive electrode active material can be, for example, a lithium-containing composite oxide. More specifically, the positive electrode active material can be a lithium transition metal composite oxide comprising lithium and at least one transition metal selected from the group consisting of cobalt, nickel, manganese, and iron. That is, such a lithium transition metal composite oxide can be included as the positive electrode active material in the positive electrode material layer of the secondary battery disclosed herein. For example, the positive electrode active material can be lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium iron phosphate, or a substance obtained by replacing a portion of their transition metals with other metals. Such a positive electrode active material can be contained individually or in combination with two or more.

[0061] There are no particular limitations on the adhesive that can be included in the positive electrode material layer, and examples include polymeric compounds. Specifically, at least one can be selected from the group consisting of styrene-butadiene rubber, polyacrylic acid, polyimide resin, polyamide-imide resin, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, and polytetrafluoroethylene.

[0062] There are no particular limitations on the conductive additives that can be included in the positive electrode material layer. Examples include carbon blacks such as thermal cracking carbon 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 polyphenylene derivatives.

[0063] There are no particular restrictions on the thickness of the positive electrode material layer; it can be greater than 1 μm and less than 300 μm, for example, greater than 5 μm and less than 200 μm. The thickness of the positive electrode material layer is the thickness inside the secondary battery, and can be the average of any ten measurements taken.

[0064] The negative electrode active material can be a substance that facilitates the insertion and extraction of lithium ions. In this sense, the negative electrode active material can be, for example, various carbon materials, oxides, lithium alloys, and / or lithium metal.

[0065] Various carbon materials that can be used as negative electrode active materials include graphite (natural and / or artificial graphite), hard carbon, soft carbon, and / or diamond-like carbon. In particular, graphite has high electronic conductivity, and for example, excellent adhesion to the negative electrode current collector.

[0066] Oxides that can be used as negative electrode active materials include at least one selected from the group consisting of silicon oxide, tin oxide, indium oxide, zinc oxide, and lithium oxide.

[0067] The lithium alloy for the negative electrode active material can be any alloy of lithium and a metal that can form an alloy with lithium. Examples include binary, ternary, or higher alloys of lithium with metals such as Al, Si, Pb, Sn, In, Bi, Ag, Ba, Ca, Hg, Pd, Pt, Te, Zn, and La. Such oxides can have an amorphous structure. This is because they are less prone to degradation caused by inhomogeneities such as grain boundaries or defects.

[0068] There are no particular limitations on the adhesive that can be included in the negative electrode material layer, and examples include polymeric compounds. Specifically, at least one selected from the group consisting of styrene-butadiene rubber, polyacrylic acid, polyimide resin, polyamide-imide resin, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, and polytetrafluoroethylene can be used.

[0069] There are no particular limitations on the conductive additives that can be included in the negative electrode material layer. Examples include carbon blacks such as thermal cracking carbon 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 polyphenylene derivatives.

[0070] There are no particular restrictions on the thickness of the negative electrode material layer; it can be greater than 1 μm and less than 300 μm, for example, greater than 5 μm and less than 200 μm. The thickness of the negative electrode material layer is the thickness inside the secondary battery, and can be the average of any ten measurements taken.

[0071] Positive and negative electrode current collectors, which can be used for both the positive and negative electrodes, are components that help to collect or supply electrons generated in the electrode active material due to the battery reaction. Such electrode current collectors can be sheet-like metal components. Furthermore, electrode current collectors can have a porous or perforated shape. For example, electrode current collectors can be metal foils, perforated metal, mesh, or expanded metal. The positive electrode current collector, which can be used for the positive electrode, can be made of a metal foil containing at least one selected from the group consisting of aluminum, stainless steel (SUS), and nickel, for example, aluminum foil. On the other hand, the negative electrode current collector, which can be used for the negative electrode, can be made of a metal foil containing at least one selected from the group consisting of copper, stainless steel (SUS), and nickel, for example, copper foil.

[0072] In this disclosure, "stainless steel" (SUS) means, for example, the stainless steel specified in JIS G 0203 Steel Terminology, which may be an alloy steel containing chromium or chromium and nickel.

[0073] There are no particular restrictions on the thickness dimensions of the positive and negative current collectors; they can be greater than 1 μm and less than 100 μm, for example, greater than 10 μm and less than 70 μm. The thickness dimensions of the positive and negative current collectors refer to the internal thickness of the secondary battery, and can be the average of any ten measurements taken.

[0074] A separator, which can be used for both the positive and negative electrodes, is a component designed to prevent short circuits caused by contact between the positive and negative electrodes and to retain the electrolyte. In other words, a separator can be described as a component that prevents electron contact between the positive and negative electrodes while allowing ions to pass through. For example, a separator can be a porous or microporous insulating component, and due to its small thickness, it can have a membrane morphology. A microporous membrane made of polyolefin can be used as a separator, but this is merely an example. In this regard, a microporous membrane that can be used as a separator can, for example, contain only polyethylene (PE) or only polypropylene (PP) as a polyolefin. Furthermore, the separator can also be a laminate composed of a "microporous membrane made of PE" and a "microporous membrane made of PP". The surface of the separator can also be covered with an inorganic particle coating and / or an adhesive layer. The surface of the separator can also be adhesive. It should be noted that in this disclosure, the term "separator" should not be specifically limited to its name, and can also refer to a solid electrolyte, a gel electrolyte, and / or insulating inorganic particles, etc., with the same function.

[0075] There are no particular restrictions on the thickness of the separator; it 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 and negative electrodes), and can be the average of ten measurements taken at any point.

[0076] In the secondary battery disclosed herein, an electrode assembly consisting of an electrode layer including a positive electrode, a negative electrode, and a separator is generally encapsulated together with an electrolyte in an outer casing. The electrolyte can be a "non-aqueous" electrolyte containing organic electrolytes and / or organic solvents, or it can be an "aqueous" electrolyte containing water. When the positive and negative electrodes have layers capable of intercalating and deintercalating lithium ions, the electrolyte can be a "non-aqueous" electrolyte. That is, the electrolyte can be a non-aqueous electrolyte or a non-aqueous electrolyte solution. The electrolyte contains metal ions that have been intercalated or deintercalated from the electrodes (positive and / or negative electrodes), thus facilitating the movement of metal ions in the battery reaction. An electrolyte that facilitates lithium ion movement can be used. It should be noted that the electrolyte can be in a liquid or gel-like form.

[0077] A non-aqueous electrolyte is an electrolyte comprising a solvent and a solute. The solvent can be an organic solvent. Specifically, an organic solvent for a non-aqueous electrolyte can be an organic solvent comprising at least a carbonate. Such a carbonate can be a cyclic carbonate and / or a chain carbonate. While not particularly limited, examples of cyclic carbonates include at least one selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), butenyl carbonate (BC), and vinylene carbonate (VC). Examples of chain carbonates include at least one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), and dipropyl carbonate (DPC). Combinations of cyclic and chain carbonates can be used as non-aqueous electrolytes, such as a mixture of ethylene carbonate and diethyl carbonate, but this is merely an example. Additionally, a specific solute for a non-aqueous electrolyte can be a Li salt such as LiPF6 and / or LiBF4.

[0078] In this disclosure, the term "outer casing" may generally refer to a component capable of housing or enclosing an electrode assembly together with an electrolyte as needed, the electrode assembly being formed by stacking at least one electrode constituent layer comprising a positive electrode, a negative electrode, and a separator.

[0079] The outer casing can be, for example, a non-laminated metal casing. A non-laminated metal casing is not a laminated component like one composed of metal sheets / welded layers / protective layers, but rather has a structure formed from a single metal component. For example, a metal casing can also be a single component made of metals such as stainless steel (SUS) or aluminum. The term "single metal component" here broadly means that the casing does not have a laminated structure; narrowly, it means that the casing is essentially a component made entirely of metal. Therefore, as long as it is essentially a component made entirely of metal, the surface of the metal casing can be appropriately surface-treated.

[0080] The thickness of the metal casing is, for example, 50 μm or more and 300 μm or less, preferably 50 μm or more and 200 μm or less. By using such a thin casing, it is possible to contribute to the miniaturization of the secondary battery and the improvement of its energy density.

[0081] The outer casing can be a metal casing. Furthermore, such a metal casing can be a two-part structure consisting of a cup-shaped component and a lid-shaped component. Each of the cup-shaped component and the lid-shaped component can be a single metal component.

[0082] In this disclosure, the "insulating component" included in the secondary battery is a component that serves to "insulate" between the "outer body" and the "flat terminal" described in detail below. There are no particular limitations on the type of insulating component as long as it exhibits "insulation". The insulating component may not only have "insulation" but also "adhesiveness" and / or "welding properties".

[0083] As an insulating component, materials such as resin, elastomer, and glass can be used.

[0084] As a resin material, a heat-melting resin can be used, for example. Examples of heat-melting resins include polyolefin resins such as polyethylene and / or polypropylene, and their copolymers. The heat-melting resin can also be chemically modified. As an insulating component, a single-layer film of heat-melting resin, a multilayer film containing heat-melting resin, etc., can be used. Examples of multilayer films include a multilayer heat-melting film in which a low-melting-point resin layer (e.g., a heat-melting resin layer) sandwiches a high-melting-point resin layer as an intermediate layer on both sides.

[0085] From another perspective, resin materials can also contain adhesive components that provide insulation. Examples of such adhesives include: acrylic adhesives such as acrylate copolymers, rubber adhesives such as natural rubber, silicone adhesives such as silicone rubber, urethane adhesives such as urethane resins, α-olefin adhesives, ether adhesives, ethylene-vinyl acetate resin adhesives, epoxy resin adhesives, vinyl chloride resin adhesives, chloroprene rubber adhesives, cyanoacrylate adhesives, waterborne polymer-isocyanate adhesives, styrene-butadiene rubber adhesives, nitrile rubber adhesives, and 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, etc.

[0086] Examples of elastomer materials include polyester-based thermoplastic elastomers.

[0087] Examples of glass materials include low-melting-point oxide glasses such as borate, silicate, germanate, vanadate, and phosphate glass.

[0088] The insulating component can consist of one or more layers, and the number of layers is not particularly limited. The thickness of the insulating component is, for example, 10 μm or more and 100 μm or less, preferably 10 μm or more and 50 μm or less.

[0089] [Features of the battery disclosed herein]

[0090] The secondary battery of the present invention is characterized by an outer casing and surrounding components capable of housing or enclosing electrode assemblies and electrolyte as needed. In particular, it is characterized by elements associated with the outer casing of the secondary battery and "flat terminals" that can function as electrode terminals (i.e., positive or negative terminals) mounted on the outer casing.

[0091] Specifically, the secondary battery of the present invention is characterized in that it includes an electrode assembly and an outer casing capable of housing or enclosing the electrode assembly and an electrolyte as needed, wherein the outer casing has a flat plate terminal engaged with an insulating member.

[0092] The secondary battery disclosed herein may include a "flat terminal" comprising a "first terminal component" and a "second terminal component", the first terminal component and the second terminal component being formed of materials having different "coefficients of linear expansion".

[0093] In this disclosure, the "coefficient of linear expansion" is also referred to as the "rate of linear expansion," which generally refers to the amount of expansion or contraction per unit length of an object due to a temperature change of one unit temperature (e.g., 1 K or 1 °C). For example, objects such as metals expand when the temperature rises and contract when the temperature falls. With the length of such an object denoted as l and the temperature denoted as T, the coefficient of linear expansion β can be expressed by the following formula.

[0094] [Mathematical Expression 1]

[0095]

[0096] In this disclosure, there are no particular limitations on the materials that can be used to form the first terminal component and the second terminal component, as long as the first terminal component and the second terminal component are formed of materials having different coefficients of linear expansion.

[0097] For example, such as Figure 1 According to one embodiment of the secondary battery 10 disclosed herein, in the flat terminal 5, a first terminal component 1 and a second terminal component 2 can be stacked on top of each other, with the first terminal component 1 stacked on top of the second terminal component 2. The second terminal component 2 included in the flat terminal 5 can be disposed on top of the insulating component 3 in a manner that directly or indirectly opposes the insulating component 3.

[0098] In this disclosure, the shape of the first terminal component and the second terminal component that may be included in the flat terminal is not particularly limited. Both the first terminal component and the second terminal component can be flat. The first terminal component and the second terminal component can have the same size and / or shape.

[0099] In this disclosure, the material capable of forming the first terminal component is preferably a metal or alloy, more preferably a combination of aluminum, stainless steel (SUS), copper, and nickel. The material capable of forming the first terminal component may also be carbon or a conductive resin.

[0100] In this disclosure, the material capable of forming the second terminal component is preferably a metal or alloy, more preferably a combination of aluminum, stainless steel (SUS), copper, and nickel. The material capable of forming the second terminal component may also be carbon or a conductive resin.

[0101] When the material is aluminum, the coefficient of linear expansion is approximately 23 × 10⁻⁶. -6 / K.

[0102] In the case of stainless steel (SUS), the coefficient of linear expansion is approximately 17 × 10⁻⁶. -6 / K.

[0103] In the case of copper, the coefficient of linear expansion is approximately 17 × 10⁻⁶. -6 / K.

[0104] In the case of nickel, the coefficient of linear expansion is approximately 13 × 10⁻⁶. -6 / K.

[0105] There are no particular restrictions on the combination of materials forming the first terminal component and materials forming the second terminal component, provided that the first terminal component and the second terminal component have different coefficients of linear expansion.

[0106] In this disclosure, a first terminal component and a second terminal component can be combined to form a flat terminal. The flat terminal can be formed of a clad material, which is composed of the first terminal component and the second terminal component. In this disclosure, not only the first terminal component and the second terminal component can be stacked in the flat terminal, but also layers of other terminal components can be arbitrarily stacked.

[0107] Examples of stacked layers of three or more include a third terminal component disposed between the first terminal component and the second terminal component, and a fourth terminal component disposed in contact with the first terminal component and located on the opposite side of the insulating component. There are no particular limitations on the materials used to construct the third and fourth terminal components; the same materials as the first and second terminal components can also be used.

[0108] The first terminal component and the second terminal component may each independently have a plating layer or surface treatment layer with a thickness of less than 10% relative to each other. The plating layer or surface treatment layer may be formed of a material containing chromium or nickel.

[0109] Because the first terminal component and the second terminal component have different coefficients of linear expansion, the flat terminal can be displaced or deformed and warped as the temperature rises.

[0110] For example, such as Figure 3 As shown, the flat terminal can bend upwards as a whole. For example, it can be bent into a dome shape or an arc shape. Specifically, it can bend upwards in the center when viewed in cross-section. In other words, it can bend downwards at both ends when viewed in cross-section.

[0111] For example, such as Figure 5 As shown, the flat terminal can also bend downwards as a whole. For example, it can be bent into a mortar shape or an arc shape. Specifically, it can bend downwards in the center when viewed in cross-section. In other words, it can bend upwards at both ends when viewed in cross-section.

[0112] For example, the flat terminal warps due to temperature rise, thus allowing the flat terminal to be at least partially peeled off from the insulating component (see reference). Figure 2 (B) and Figure 4 (B)). When pressure is applied from inside the battery under such conditions, the seal can be cracked with lower pressure.

[0113] In this disclosure, "closure" means the portion formed by bonding a flat terminal to the outer casing via an insulating component on the surface of the outer casing, particularly around an opening. A closure can be, for example, shown as... Figure 1 The part enclosed in dashed circles.

[0114] In this disclosure, "crack" in the "closure" generally means that the connection between the flat terminal and the insulating component is released. In other words, it means that the flat terminal and the insulating component are not connected. Additionally, "crack" in the "closure" may also include the release of the connection between the insulating component and the outer casing.

[0115] The pressure inside the battery when the seal is about to "crack" is called the "cracking pressure." The "cracking pressure" generally depends on the bonding area between the flat terminal and the insulating component (e.g., reference...). Figure 13 In other words, "cracking pressure" is inversely related to "bonding area" and "sealing". However, in the secondary battery disclosed herein, "cracking pressure" can be further reduced by generating thermal stress during heating to warp the flat terminals, while ensuring "bonding area" and "sealing", in other words, without reducing the sealing.

[0116] In this disclosure, the coefficient of linear expansion of the first terminal component can be greater than that of the second terminal component. In other words, the coefficient of linear expansion of the second terminal component can be less than that of the first terminal component.

[0117] Alternatively, the coefficient of linear expansion of the second terminal component can be greater than that of the first terminal component. In other words, the coefficient of linear expansion of the first terminal component can be less than that of the second terminal component.

[0118] When the coefficient of linear expansion of the first terminal component is greater than that of the second terminal component, for example, as Figure 3 As shown, the central portion of the flat terminal can bend upwards when viewed in cross-section.

[0119] For example, when the material forming the first terminal component is aluminum and the material forming the second terminal component is selected from the group consisting of stainless steel, copper, and nickel, or when the material forming the second terminal component is nickel and the material forming the first terminal component is selected from the group consisting of aluminum, stainless steel, and copper, the coefficient of linear expansion of the first terminal component is greater than the coefficient of linear expansion of the second terminal component. For example, as... Figure 3 As shown, the central portion of the flat terminal can bend upwards when viewed in cross-section. Furthermore, this combination allows for the formation of a more stable electrode within the operating potential range.

[0120] When the coefficient of linear expansion of the second terminal component is greater than that of the first terminal component, for example, as Figure 5 As shown, the central portion of the flat terminal can bend downwards when viewed in cross-section.

[0121] For example, when the material forming the first terminal component is nickel and the material forming the second terminal component is selected from the group consisting of aluminum, stainless steel, and copper, or when the material forming the second terminal component is aluminum and the material forming the first terminal component is selected from the group consisting of stainless steel, copper, and nickel, the coefficient of linear expansion of the second terminal component is greater than that of the first terminal component. For example, as... Figure 5 As shown, the central portion of the flat terminal can bend downwards when viewed in cross-section. Furthermore, this combination facilitates soldering to the lead body and external terminals. It also provides resistance to electrolyte corrosion.

[0122] It should be noted that when the material forming the first terminal component is stainless steel and the material forming the second terminal component is selected from the group consisting of aluminum, copper and nickel, or when the material forming the second terminal component is stainless steel and the material forming the first terminal component is selected from the group consisting of aluminum, copper and nickel, the central part of the flat terminal can be arbitrarily warped upward and downward when viewed in cross-section.

[0123] To achieve the aforementioned warping of the flat terminal, the difference between the linear expansion coefficients of the first terminal component and the second terminal component can be 5 × 10⁻⁶. -6 / K or above.

[0124] The following describes the secondary battery of this disclosure in detail with more specific embodiments.

[0125] [Implementation Method]

[0126] Figure 1 This illustration shows a secondary battery 10 according to one embodiment of the present disclosure.

[0127] For example, such as Figure 1As shown in (A), the secondary battery 10 can mainly consist of a flat terminal 5 formed by combining a first terminal component 1 and a second terminal component 2, an insulating component 3, and an electrode assembly 11 (see, for example, reference 1). Figure 10 It consists of an electrode assembly 11 and an outer casing 4 capable of housing the electrolyte as needed.

[0128] The outer casing 4 may have an opening on its top through which a lead (not shown) can be configured to electrically connect the electrode assembly 11 (more specifically, the positive or negative electrode) to the flat terminal 5.

[0129] An insulating member 3, for example, in the shape of a disc, preferably in the shape of a donut when viewed from above, may be disposed on the outer surface around the opening of the outer casing 4. Above the insulating member 3, a plate-shaped terminal 5 may be disposed in such a way that at least a portion of the second terminal member 2 of the plate-shaped terminal 5 contacts the insulating member 3.

[0130] The flat plate terminal 5 can have a disc-shaped shape. When the flat plate terminal 5 has a disc-shaped shape, its diameter is not particularly limited, for example, it is 5mm to 10mm.

[0131] By connecting the outer casing 4 to the flat terminal 5 through the insulating component 3, for example, it is possible to form a structure such as... Figure 1 The closed portion is shown by the dashed line in (A). For example, the aforementioned bond can be formed by the adhesiveness and / or fusion of the insulating component 3. Such a closed portion ensures sealing.

[0132] Figure 1 (B) schematically shows the closed portion. For example, in the event of gas generation or pressure increase inside the battery due to abnormal temperature rise (e.g., above 40°C and below 120°C) during charging and discharging, the flat terminal 5, especially the second terminal component 2, is pressed with force (F1) along the arrow. Here, the second terminal component 2 may also be referred to as the "inner terminal component" and the first terminal component 1 as the "outer terminal component".

[0133] In the flat terminal 5, the first terminal component 1 and the second terminal component 2 can be formed of materials with different coefficients of linear expansion, wherein the coefficient of linear expansion of the first terminal component 1 is greater than that of the second terminal component 2.

[0134] For example, during charging and discharging, within a typical temperature range (e.g., above 0°C and below 40°C), preferably at an ambient temperature (e.g., 25°C), for example, as... Figure 2 As shown in (A) schematically, no "warping" is formed in the flat terminal 5, which can maintain a high seal.

[0135] For example, if an abnormal temperature rise occurs during charging and discharging, then, for example... Figure 2 As schematically shown in (B), the temperature rise causes "warping" in the flat terminal 5, allowing the flat terminal 5 to peel off at least partially from the insulating member 3. In this disclosure, peeling is sufficient on either the left or right joint ends of the flat terminal 5.

[0136] Under these conditions, the closure can be cracked with a smaller force (F1). That is, the closure can be cracked with a lower internal pressure.

[0137] There are no particular restrictions on the thickness of the components here. For example, such as Figure 1 As shown in (B), the thickness T1 of the first terminal component 1 is, for example, 50 μm to 150 μm. The thickness T2 of the second terminal component 2 is, for example, 50 μm to 150 μm. The overall thickness T0 (=T1+T2) of the flat terminal 5 is, for example, 100 μm to 300 μm.

[0138] The ratio (T1 / T2) of the thickness T1 of the first terminal component 1 to the thickness T2 of the second terminal component 2 is not particularly limited; for example, it can be 1 / 1.

[0139] The thickness T3 of the insulating component 3 is, for example, 10 μm to 100 μm.

[0140] The thickness T4 of the outer casing 4 is, for example, 50 μm to 200 μm.

[0141] For example, in Figure 3 The diagram schematically illustrates the upward warping of the flat plate terminal 5. The magnitude of the warping D1 (or the displacement of the center or end portion) of the flat plate terminal 5 is not particularly limited, but is, for example, 1 μm or more, preferably 10 μm or more, more preferably 20 μm or more, and even more preferably 40 μm or more. The magnitude of the warping D1 of the flat plate terminal 5 is preferably 50 μm or less.

[0142] Figure 4 A secondary battery 20 according to another embodiment is shown.

[0143] For example, such as Figure 4 As shown in (A), the secondary battery 20 can be mainly composed of a flat terminal 25 formed by combining a first terminal component 21 and a second terminal component 22, an insulating component 23, and an electrode assembly 11 (see reference). Figure 10 It consists of an electrode assembly 11 and an outer casing 24 capable of housing the electrolyte as needed.

[0144] In the secondary battery 20, the insulating component 23, the outer casing 24, and the flat terminal 25 can respectively correspond to Figure 1The secondary battery 10 shown includes the insulating component 3, the outer casing 4, and the flat terminal 5. However, regarding... Figure 4 The flat terminal 25 shown includes a first terminal component 21 and a second terminal component 22, wherein the coefficient of linear expansion of the second terminal component 22 is greater than that of the first terminal component 21.

[0145] In the flat terminal 25, since the coefficient of linear expansion of the second terminal component 22 is greater than that of the first terminal component 21, therefore, for example... Figure 4 As shown schematically in (B), if an abnormal temperature rise occurs during charging and discharging, the flat terminal 25 is affected by the temperature rise, and when viewed in cross-section, the central part of the flat terminal 25 is "warped" downwards, and the flat terminal 25, especially the end, can be at least partially peeled off from the insulating member 33.

[0146] For example, in Figure 5 The diagram schematically shows the flat terminal 25 warped downwards. The magnitude of the warping D2 (or the displacement of the center or end) of the flat terminal 25 is not particularly limited, but is, for example, 1 μm or more, preferably 10 μm or more, more preferably 20 μm or more, and even more preferably 40 μm or more.

[0147] In the secondary battery 20, it is also possible to ensure sealing while allowing the seal to crack under lower pressure when the internal pressure rises due to abnormal temperature.

[0148] Figure 6 A secondary battery 30 according to another embodiment is shown.

[0149] The secondary battery 30 can be mainly composed of a flat terminal 35 formed by combining a first terminal component 31 and a second terminal component 32, an insulating component 33, and an electrode assembly 11 (see reference). Figure 10 It consists of an electrode assembly 11 and an outer casing 34 capable of housing the electrolyte as needed.

[0150] In the secondary battery 30, the insulating component 33, the outer casing 34, and the flat terminal 35 can respectively correspond to Figure 4 The secondary battery 20 shown includes an insulating component 23, an outer casing 24, and a flat terminal 25. However, in Figure 6In the secondary battery 30 shown, the outer casing 34 is configured to deform upwards even when the internal pressure increases due to abnormal heating. For example, by reducing the thickness of the outer casing 34 or changing the material, the outer casing 34 can be deformed upwards. With this configuration, the warping shape of the flat terminal 35 does not follow the deformation of the outer casing 34, thus further reducing the contact area between the second terminal component 32 of the flat terminal 35 and the insulating component 33. Therefore, in the event of an abnormal increase in internal pressure due to heating, the seal can crack under even lower pressure.

[0151] The displacement D3 of the periphery of the opening of the outer body 34 is not particularly limited, for example, it is 1 μm or more, preferably 10 μm or more, more preferably 20 μm or more, and even more preferably 40 μm or more.

[0152] Figure 7 A secondary battery 40 according to another embodiment is shown.

[0153] The secondary battery 40 can be mainly composed of a flat terminal 45 formed by combining a first terminal component 41 and a second terminal component 42, an insulating component 43, and an electrode assembly 11 (see reference). Figure 10 It consists of an electrode assembly 11 and an outer casing 44 capable of housing the electrolyte as needed.

[0154] In the secondary battery 40, the insulating component 43, the outer casing 44, and the flat terminal 45 can respectively correspond to Figure 4 The secondary battery 20 shown includes an insulating component 23, an outer casing 24, and a flat terminal 25. However, Figure 7 The insulating component 43 of the secondary battery 40 shown may have a raised portion 43b that covers at least a portion of the peripheral edge of the flat terminal 45 (see reference). Figure 8 ).

[0155] In this disclosure, the term "peripheral edge" of a flat terminal generally refers to the side of a flat terminal other than its two main surfaces.

[0156] More specifically, such as Figure 8 As shown in (A), the insulating member 43 has a flat portion 43a and a raised portion 43b.

[0157] For example, such as Figure 8 As shown in (A), the raised portion 43b can cover at least a portion of the peripheral edge of the flat terminal 45, particularly the peripheral edge of the second terminal member 42. With this configuration, the bonding and sealing between the flat terminal 45 and the insulating member 43 can be further improved.

[0158] Thickness T of raised portion 43b 3bThe thickness T0 of the flat terminal 45 can be more than 5% and less than 20%. More specifically, Figure 8 The thickness T of the raised portion 43b shown in (A) 3b The ratio of the thickness T0 relative to the flat terminal (T) 3b / T0) can be, for example, greater than 1 / 20 and less than 1 / 5. Within this range, sealing is ensured, and the cracking of the sealed portion during heating is smoothly promoted. It should be noted that T 3b The ratio of / T0 can also be more than 1 / 2, and the raised portion 43b can also cover at least a portion of the peripheral edge of the first terminal component 41.

[0159] Thickness T of raised portion 43b 3b For example, the size is 10μm or larger and 50μm or smaller, preferably 10μm or larger and 40μm or smaller.

[0160] Figure 8 (B) schematically shows the flat terminal 45 warped downwards. More specifically, as... Figure 9 As shown, the warpage size D4 (displacement at the end) of the flat terminal 45 is not particularly limited, for example, it is 10 μm or more, preferably 20 μm or more, and more preferably 40 μm or more.

[0161] The warpage D4 of the flat terminal 45 is preferably greater than 1. Figure 8 The thickness T of the raised portion 43b shown in (A) 3b .

[0162] The secondary battery disclosed herein should not be interpreted as limited to the above-described embodiments.

[0163] (Other components)

[0164] In this disclosure, "lead" or "tack" refers to a conductive component that can be electrically connected to the positive or negative electrode of an electrode assembly, and can protrude or extend from the electrode assembly. Such a tack can be mounted on the inner main surface of a flat terminal, particularly an inner terminal component, at least through an opening in the outer casing, and can provide an electrical connection between the inner terminal component and either the positive or negative electrode layer of the electrode assembly. Such a lead or tack can extend from the "current collector" (i.e., "positive current collector" or "negative current collector") described above, and can be made of the same material as such a current collector.

[0165] In this disclosure, the flat terminal can be an electrode terminal. The flat terminal can be one of the positive and negative electrodes, while the outer casing is the other. In particular, in the secondary battery of this disclosure, the flat terminal can be the positive electrode, and the outer casing can be the negative electrode. By forming such a configuration, the negative electrode can be greater than the positive electrode.

[0166] Therefore, the outer casing can be a metal outer casing. The metal outer casing can be a two-piece structure consisting of a cup-shaped component and a cap-shaped component.

[0167] The secondary battery disclosed herein can be a circular secondary battery when viewed from above, or a secondary battery with an overall generally cylindrical shape, such as a button or coin shape (see reference...). Figure 11 (a)). However, the secondary battery disclosed herein is not limited to secondary batteries having a button-shaped or coin-shaped shape. The secondary battery disclosed herein may also be, for example, a secondary battery having an angular shape (see, for example, reference to...). Figure 11 (b)). That is to say, the top view shape of the secondary battery disclosed herein is not limited to a circle, but may also have a quadrilateral, rectangular or other shapes.

[0168] In addition, Figure 11 In the manner shown, the flat plate terminal is represented as a circle, but it can be rectangular or other geometric shapes.

[0169] In the secondary battery disclosed herein, the electrodes serving as electrode components may include a positive electrode and a negative electrode capable of intercalating and deintercalating lithium ions. Such a secondary battery can be used as a lithium-ion secondary battery. However, the secondary battery disclosed herein is not limited to lithium-ion secondary batteries.

[0170] (Manufacturing method)

[0171] The secondary battery disclosed herein, particularly the configuration near the electrode terminals (or terminal components), can be manufactured in the same manner as conventionally known manufacturing methods.

[0172] Specifically, by stacking a flat terminal, an insulating component with an opening, and an outer casing with an opening in this order, and heating and pressurizing simultaneously, the configuration near the electrode terminal (or terminal component) according to the invention can be formed.

[0173] There are no particular limitations on the method of joining the first terminal component and the second terminal component in the flat terminal. For example, conventionally known methods of joining metal plates can be used without particular limitation.

[0174] The following are several embodiments to provide a detailed description of the secondary battery disclosed herein.

[0175] Example

[0176] [Example 1]

[0177] As a secondary battery of Example 1, for example, a... Figure 1The diagram schematically shows a secondary battery 10 with a button-shaped structure. The components are described below. The electrode assembly 11 is manufactured according to conventional electrode assembly methods.

[0178] Flat plate terminal 5: Coating material (bimetallic) for the first terminal component 1 and the second terminal component 2

[0179] First terminal component 1: linear expansion coefficient 23×10 -6 / K aluminum (Al)

[0180] Second terminal component 2: linear expansion coefficient 17×10 -6 / K Stainless Steel (SUS304)

[0181] Insulating component 3: Modified polypropylene

[0182] Outer casing 4: Stainless steel (SUS304)

[0183] The outer body 4 is formed as a two-piece structure consisting of a cylindrical cup-shaped component and a disc-shaped cover-shaped component, with a circular opening in the center of the cover-shaped component.

[0184] The electrode assembly 11 and the non-aqueous electrolyte are disposed together inside the cylindrical cup-shaped component of the outer casing 4, and the cup-shaped component is closed by welding with a cap-shaped component. At this time, the positive electrode of the electrode assembly 11 is electrically connected to the second terminal component 2 of the flat terminal 5 via a contact, and similarly, the negative electrode of the electrode assembly 11 is electrically connected to the cup-shaped component of the outer casing 4 via a contact.

[0185] A concentric disc-shaped insulating component 3 with the same opening is arranged around the circular opening of the cover-shaped component.

[0186] A disc-shaped flat terminal 5 is further disposed on the upper surface of the insulating component 3 by pressing while heating. At this time, the second terminal component 2 of the flat terminal 5 is bonded to the insulating component 3.

[0187] In the secondary battery 10 of Example 1, during the heating to 120°C, thermal stress is generated between the first terminal component 1 and the second terminal component 2 of the flat terminal 5 due to the difference in the coefficient of linear expansion. The central portion of the flat terminal 5 warps upwards due to this thermal stress, thereby exerting a force that causes the adhesive surface between the second terminal component 2 and the insulating component 3 to peel off (see reference). Figure 2 (B) As a result, due to the increase in internal pressure of the secondary battery 10, the closure formed by the flat terminal 5 and the insulating member 3 on the surface around the opening of the outer casing 4 cracks.

[0188] The results above confirm that almost no thermal stress is generated in the normal operating temperature range of the battery (e.g., room temperature (25°C)), thus ensuring sealing. Under abnormal temperature rise conditions, the flat terminal 5 warps, thereby causing the seal to crack under lower pressure.

[0189] [Example 2]

[0190] Except for using the following flat terminals, it was manufactured in the same manner as in Example 1. Figure 1 The secondary battery 10 is shown.

[0191] Flat terminal 5: Coating material for the first terminal component 1 and the second terminal component 2

[0192] First terminal component 1: linear expansion coefficient 23×10 -6 / K aluminum (Al)

[0193] Second terminal component 2: linear expansion coefficient 13×10 -6 / K of nickel (Ni)

[0194] The same results as in Example 1 can be obtained.

[0195] [Example 3]

[0196] Except for using the following flat terminals, it was manufactured in the same manner as in Example 1. Figure 1 The secondary battery 10 is shown.

[0197] Flat terminal 5: Coating material for the first terminal component 1 and the second terminal component 2

[0198] First terminal component 1: linear expansion coefficient 17×10 -6 / K stainless steel (SUS304)

[0199] Second terminal component 2: linear expansion coefficient 13×10 -6 / K of nickel (Ni)

[0200] The same results as in Example 1 can be obtained.

[0201] [Example 4]

[0202] Except for using the following flat terminals, it was manufactured in the same manner as in Example 1. Figure 4 The secondary battery 20 is shown.

[0203] Flat terminal 25: Coating material for the first terminal component 21 and the second terminal component 22

[0204] First terminal component 21: linear expansion coefficient 17×10 -6 / K stainless steel (SUS304)

[0205] Second terminal component 22: linear expansion coefficient 23×10 -6 / K aluminum (Al)

[0206] In secondary battery 20, such as Figure 4 As shown in (B), the central portion of the flat terminal 25 warps downward, thereby causing the seal to crack under lower pressure during abnormal heating.

[0207] [Example 5]

[0208] Except for using the following flat terminals, it was manufactured in the same manner as in Example 4. Figure 4 The secondary battery 20 is shown.

[0209] Flat terminal 25: Coating material for the first terminal component 21 and the second terminal component 22

[0210] First terminal component 21: linear expansion coefficient 13×10 -6 / K of nickel (Ni)

[0211] Second terminal component 22: linear expansion coefficient 17×10 -6 / K stainless steel (SUS304)

[0212] In the secondary battery 20, such as Figure 4 As shown in (B), the central portion of the flat terminal 25 warps downward, thereby causing the seal to crack under lower pressure during abnormal heating.

[0213] [Example 6]

[0214] Except for using the following flat terminals, it was manufactured in the same manner as in Example 4. Figure 4 The secondary battery 20 is shown.

[0215] Flat terminal 25: Coating material for the first terminal component 21 and the second terminal component 22

[0216] First terminal component 21: linear expansion coefficient 13×10 -6 / K of nickel (Ni)

[0217] Second terminal component 22: linear expansion coefficient 23×10 -6 / K aluminum (Al)

[0218] In the secondary battery 20, such as Figure 4 As shown in (B), the central portion of the flat terminal 25 warps downward, thereby causing the seal to crack under lower pressure during abnormal heating.

[0219] Figure 12The flat terminal is shown when heated from room temperature (25°C) to 120°C. Warping of the outer periphery. A warping of about 40 μm occurred from the center of the flat terminal 25 to the outer periphery.

[0220] Figure 13 The graph shows the relationship between the bonding area of ​​the second terminal component 22 and the insulating component 23 and the cracking pressure (at room temperature (25°C)). Figure 13 The chart shows that there is a proportional relationship between the bonding area and the cracking pressure.

[0221] The results above confirm that almost no thermal stress is generated in the normal operating temperature range of the battery (e.g., room temperature (25°C)), thus ensuring sealing. In the event of an abnormal temperature rise, the flat terminal 25 warps, thereby reducing the bonding area and causing the seal to crack under lower pressure.

[0222] [Examples 7-9]

[0223] Except for reducing the thickness of the outer casing, especially the cover-like component of the outer casing, it was manufactured in the same manner as in Examples 4-6. Figure 6 The secondary battery 30 shown is the secondary battery of Examples 7-9.

[0224] In secondary battery 30, such as Figure 6 As shown, the central portion of the flat terminal 35 warps downward, while the outer casing 34 warps upward in opposition to it. This results in a further reduction in the bonding area between the insulating component 33 and the second terminal component 32 during abnormal heating, causing the sealing portion to crack under even lower pressure.

[0225] [Examples 10-12]

[0226] Except for the raised portion provided in the insulating component, it was manufactured in the same manner as in Examples 4-6. Figure 7 The secondary battery 40 shown is a secondary battery of Examples 10-12.

[0227] exist Figure 7 and Figure 8 In the secondary battery 40 shown, by preparing an insulating component with a uniform thickness having an area larger than the flat terminal 45 during manufacturing, and pressing the flat terminal 45 onto the insulating component, a flat portion 43a and a raised portion 43b of the insulating component are formed (see reference). Figure 8 ).

[0228] exist Figure 7 In the secondary battery 40 shown, the height (T) of the raised portion 43b 3b Adjust it to the range of the thickness (T2) of the second terminal component 42.

[0229] The secondary batteries prepared in Examples 4-6 Figure 4 In comparison, in the secondary battery 40 of Examples 10-12, the bonding area between the second terminal component 42 and the insulating component 43 is increased, thereby improving the sealing performance within a normal temperature range (e.g., room temperature (25°C)). Figure 8 (A)). Furthermore, it can further improve safety. Moreover, in cases of abnormal temperature rise, such as Figure 8 As shown in (B), the flat terminal 45 warps, thereby reducing the bonding area between the second terminal component 42 and the flat portion 43a of the insulating component, enabling the closure to crack under lower pressure.

[0230] The embodiments of the present invention have been described above, but these are merely illustrative examples. Therefore, those skilled in the art should readily understand that the present invention is not limited thereto, and various other approaches can be considered.

[0231] (Method 1)

[0232] A secondary battery includes an electrode assembly and an outer casing for housing the electrode assembly.

[0233] The outer casing has flat, plate-shaped terminals that are joined together with an insulating component.

[0234] The flat terminal is composed of a first terminal component and a second terminal component.

[0235] The first terminal component and the second terminal component are formed of materials having different coefficients of linear expansion.

[0236] The first terminal component and the second terminal component are stacked on top of each other in such a way that the first terminal component is stacked on top of the second terminal component.

[0237] The flat terminal is disposed on the insulating component in such a manner that the second terminal component is opposite to the insulating component.

[0238] (Method 2)

[0239] According to the secondary battery described in method 1, wherein...

[0240] The flat terminal is peeled off from the insulating component as it warps due to increased temperature.

[0241] (Method 3)

[0242] According to method 1 or 2, the secondary battery, wherein...

[0243] The coefficient of linear expansion of the first terminal component is greater than that of the second terminal component.

[0244] (Method 4)

[0245] According to method 1 or 2, the secondary battery, wherein...

[0246] The coefficient of linear expansion of the second terminal component is greater than that of the first terminal component.

[0247] (Method 5)

[0248] According to any one of methods 1 to 4, the secondary battery, wherein...

[0249] The difference between the coefficient of linear expansion of the first terminal component and the coefficient of linear expansion of the second terminal component is 5 × 10⁻⁶. -6 / K or above.

[0250] (Method 6)

[0251] According to any one of methods 1 to 5, the secondary battery, wherein...

[0252] The material used to form the first terminal component is selected from the group consisting of aluminum, stainless steel, copper, and nickel.

[0253] (Method 7)

[0254] According to any one of methods 1 to 6, the secondary battery, wherein...

[0255] The material used to form the second terminal component is selected from the group consisting of aluminum, stainless steel, copper, and nickel.

[0256] (Method 8)

[0257] According to the secondary battery described in method 1, wherein...

[0258] The material forming the first terminal component is aluminum, while the material forming the second terminal component is selected from the group consisting of stainless steel, copper, and nickel; or,

[0259] The material forming the second terminal component is nickel, while the material forming the first terminal component is selected from the group consisting of aluminum, stainless steel, and copper.

[0260] (Method 9)

[0261] According to the secondary battery described in method 1, wherein...

[0262] The material forming the first terminal component is stainless steel, while the material forming the second terminal component is selected from the group consisting of aluminum, copper, and nickel; or,

[0263] The material forming the second terminal component is stainless steel, while the material forming the first terminal component is selected from the group consisting of aluminum, copper, and nickel.

[0264] (Method 10)

[0265] According to the secondary battery described in method 1, wherein...

[0266] The material forming the first terminal component is nickel, while the material forming the second terminal component is selected from the group consisting of aluminum, stainless steel, and copper; or,

[0267] The material forming the second terminal component is aluminum, while the material forming the first terminal component is selected from the group consisting of stainless steel, copper, and nickel.

[0268] (Method 11)

[0269] According to any one of methods 1 to 10, the secondary battery, wherein...

[0270] The insulating component has a raised portion that covers at least a portion of the peripheral edge of the flat terminal.

[0271] (Method 12)

[0272] According to the secondary battery of method 11, wherein...

[0273] The thickness of the raised portion covering at least a portion of the peripheral edge of the flat terminal is more than 5% and less than 20% of the thickness of the flat terminal.

[0274] (Method 13)

[0275] The secondary battery according to any one of methods 1 to 12, wherein...

[0276] The flat terminal is one of the positive and negative terminals, and the outer casing is the other of the positive and negative terminals.

[0277] (Method 14)

[0278] The secondary battery according to any one of methods 1 to 13, wherein...

[0279] The outer casing is a metal outer casing, which is a two-piece structure consisting of a cup-shaped component and a cap-shaped component.

[0280] (Method 15)

[0281] The secondary battery according to any one of methods 1 to 14, wherein...

[0282] The secondary battery has a button-shaped or coin-shaped design.

[0283] (Method 16)

[0284] According to any one of methods 1 to 15, the secondary battery, wherein...

[0285] The electrodes of the electrode assembly include a positive electrode and a negative electrode capable of inserting and de-intercalating lithium ions.

[0286] Industrial applicability

[0287] The secondary battery disclosed herein can be used in a wide variety of conceivable fields of energy storage. It can be used in electrical / information / communication fields where electrical / electronic devices are used (e.g., electrical / electronic devices such as mobile phones, smartphones, laptops and digital cameras, activity meters, ARM computers, electronic paper, wearable devices, RFID tags, card-type electronic money, smartwatches, and other small electronic devices or mobile devices); household / small industrial applications (e.g., power tools, golf carts, home / care / industrial robots); large industrial applications (e.g., forklifts, elevators, port cranes); transportation systems (e.g., hybrid vehicles, electric vehicles, buses, trams, electric-assisted bicycles, electric two-wheelers); power systems (e.g., various power generators, load conditioners, smart grids, household stationary energy storage systems); medical applications (medical devices such as headphones and hearing aids); pharmaceutical applications (medical management systems); and the IoT field; space / deep-sea applications (e.g., space probes, underwater research vessels), etc., but the above are merely examples.

[0288] Explanation of reference numerals in the attached figures

[0289] 1, 21, 31, 41 First terminal components

[0290] 2, 22, 32, 42 Second terminal components

[0291] Insulating components 3, 23, 33, and 43

[0292] 4, 24, 34, 44 outer body

[0293] 5, 25, 35, 45 flat terminals

[0294] 10, 20, 30, 40 rechargeable batteries

[0295] Electrode assemblies 11, 111, and 211

[0296] 12 Positive electrode

[0297] 13. Diaphragm

[0298] 14 Negative electrode

[0299] 15 Electrode Constituent Layer

[0300] 100, 200 Previous batteries

[0301] 101 Flat plate electrode terminal component

[0302] 103 Sealing components

[0303] 104 External Housing

[0304] 201 External terminal

[0305] 202 gasket

[0306] 203 Pad

[0307] 204 battery can

[0308] 205 sealing board

[0309] 206 First Slot

[0310] 207 Second slot.

Claims

1. A secondary battery, said secondary battery comprising an electrode assembly and an outer casing for housing the electrode assembly, The outer casing has flat, plate-shaped terminals that are joined together with an insulating component. The flat terminal is composed of a first terminal component and a second terminal component. The first terminal component and the second terminal component are formed of materials having different coefficients of linear expansion. The first terminal component and the second terminal component are stacked on top of each other in such a way that the first terminal component is stacked on top of the second terminal component. The flat terminal is disposed on the insulating component such that the second terminal component is opposite to the insulating component. The outer casing has an opening. Around the opening on the surface of the outer casing, a closed portion is formed by connecting the outer casing to the flat terminal through the insulating member. The flat terminal is peeled off from the insulating component as it warps due to increased temperature.

2. The secondary battery according to claim 1, wherein, The coefficient of linear expansion of the first terminal component is greater than that of the second terminal component.

3. The secondary battery according to claim 1, wherein, The coefficient of linear expansion of the second terminal component is greater than that of the first terminal component. As the flat terminal warps due to increased temperature, at least partially, the end of the flat terminal peels off from the insulating component.

4. The secondary battery according to any one of claims 1 to 3, wherein, The difference between the coefficient of linear expansion of the first terminal component and the coefficient of linear expansion of the second terminal component is 5 × 10⁻⁶. -6 / K or above.

5. The secondary battery according to claim 1, wherein, The material used to form the first terminal component is selected from the group consisting of aluminum, stainless steel, copper, and nickel.

6. The secondary battery according to claim 1, wherein, The material used to form the second terminal component is selected from the group consisting of aluminum, stainless steel, copper, and nickel.

7. The secondary battery according to claim 1, wherein, The material forming the first terminal component is aluminum, while the material forming the second terminal component is selected from the group consisting of stainless steel, copper, and nickel; or, The material forming the second terminal component is nickel, while the material forming the first terminal component is selected from the group consisting of aluminum, stainless steel, and copper.

8. The secondary battery according to claim 1, wherein, The material forming the first terminal component is stainless steel, while the material forming the second terminal component is selected from the group consisting of aluminum, copper, and nickel; or, The material forming the second terminal component is stainless steel, while the material forming the first terminal component is selected from the group consisting of aluminum, copper, and nickel.

9. The secondary battery according to claim 1, wherein, The material forming the first terminal component is nickel, while the material forming the second terminal component is selected from the group consisting of aluminum, stainless steel, and copper; or, The material forming the second terminal component is aluminum, while the material forming the first terminal component is selected from the group consisting of stainless steel, copper, and nickel.

10. The secondary battery according to claim 1, wherein, The insulating component has a raised portion that covers at least a portion of the peripheral edge of the flat terminal.

11. The secondary battery according to claim 10, wherein, The thickness of the raised portion covering at least a portion of the peripheral edge of the flat terminal is more than 5% and less than 20% of the thickness of the flat terminal.

12. The secondary battery according to claim 1, wherein, The flat terminal is one of the positive and negative terminals, and the outer casing is the other of the positive and negative terminals.

13. The secondary battery according to claim 1, wherein, The outer casing is a metal casing, which is a two-piece structure consisting of a cup-shaped component and a cap-shaped component.

14. The secondary battery according to claim 1, wherein, The secondary battery has a button-shaped or coin-shaped design.

15. The secondary battery according to claim 1, wherein, The electrodes of the electrode assembly include a positive electrode and a negative electrode capable of inserting and de-intercalating lithium ions.

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