Secondary batteries

Abstract

To provide a secondary battery capable of improving a sealing property of a gasket positioned between an outer casing and a sealing body.SOLUTION: A secondary battery comprises: an outer casing having an open part at one end side; a sealing body that seals the open part; and a gasket that is interposed to between the outer casing and the sealing body. The outer casing comprises: a side wall part forming the open part; and a bottom part that is continuous to the side wall part. The side wall part comprises a beading part that is continued along an outer periphery, and is concaved in an inner side direction of the battery. The beading part comprises an inner side curving part that is curved to the inner side, and includes a gasket support wall part that is extended in the inner side direction of the battery from a concave start point, and can support the gasket. A minimum R part where a curvature diameter becomes the minimum out of the inner side curving part of the beading part in a cross sectional view is positioned above the concave start point of the gasket support wall part.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] This disclosure relates to secondary batteries. [Background technology]

[0002] Rechargeable and rechargeable secondary batteries have long been used in a variety of applications. For example, secondary batteries are used as power sources for electronic devices such as smartphones and laptop computers.

[0003] A secondary battery has a structure in which an electrode assembly, including a positive electrode, a negative electrode, and a separator placed between the positive and negative electrodes, and an electrolyte are housed in a housing. The positive electrode consists of a positive electrode material layer containing a positive electrode active material, and the negative electrode consists of a negative electrode material layer containing a negative electrode active material. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2002-231193 [Patent Document 2] Japanese Patent Application Publication No. 10-199495 [Patent Document 3] International Publication No. 2013 / 125244 [Patent Document 4] Patent No. 4509064 [Overview of the project] [Problems that the invention aims to solve]

[0005] In secondary batteries, the housing may consist of an outer casing having an opening at one end and a sealing body that seals this opening, with a gasket interposed between the outer casing and the sealing body as a sealing material. Such an outer casing may have beading on its side walls that runs continuously along the outer circumference and is recessed toward the inside of the battery.

[0006] Here, the inventor of the present application has found that there is room for improving the sealing performance by the gasket interposed between the exterior body and the sealing body in a secondary battery having such a configuration.

[0007] The present disclosure has been devised in view of such circumstances. Specifically, an object of the present disclosure is to provide a secondary battery capable of improving the sealing performance of a gasket located between an exterior body and a sealing body.

Means for Solving the Problem

[0008] In order to achieve the above object, in one embodiment of the present disclosure, it includes an exterior body having an opening portion on one end side, a sealing body for sealing the opening portion, and a gasket interposed between the exterior body and the sealing body, the exterior body includes a side wall portion forming the opening portion and a bottom portion continuous with the side wall portion, the side wall portion is continuous along the outer periphery and includes a beading portion recessed toward the inner side of the battery, the beading portion includes an inner curved portion curved inward, and has a gasket support wall portion extending from the recess start point toward the inner side of the battery and capable of supporting the gasket, In a cross-sectional view, a secondary battery is provided in which a minimum R portion having the minimum radius of curvature among the inner curved portions of the beading portion is located above the recess start point of the gasket support wall portion.

Effect of the Invention

[0009] According to the secondary battery according to one embodiment of the present disclosure, it is possible to improve the sealing performance of the gasket located between the exterior body and the sealing body.

Brief Description of the Drawings

[0010] [Figure 1] It is a cross-sectional view schematically showing a general configuration of a secondary battery including an exterior body with a beading portion. [Figure 2]This is an enlarged cross-sectional view schematically showing the beading portion of the outer casing of a secondary battery according to one embodiment of the present disclosure. [Figure 3] This is an enlarged cross-sectional view schematically showing the beading portion of the outer casing of a secondary battery as a comparative example. [Figure 4] A schematic diagram illustrating the manufacturing process of the beading portion of the outer casing in a secondary battery according to one embodiment of the present disclosure. [Figure 5] This is a schematic cross-sectional view showing the basic structure of the electrode constituent layers. [Modes for carrying out the invention]

[0011] A secondary battery according to one embodiment of this disclosure will be described below with reference to the drawings. The various elements in the drawings are shown schematically and illustratively for the purpose of understanding this disclosure, and their appearance, dimensional ratios, etc., may differ from those of the actual product.

[0012] As used herein, the term "secondary battery" refers to a battery that can be repeatedly charged and discharged. The term "secondary battery" is not overly restrictive and may also include, for example, "energy storage devices." As used herein, "cross-sectional view" refers to the state when viewed from a direction approximately perpendicular to the thickness direction based on the stacking direction of the electrode materials constituting the secondary battery. As used directly or indirectly herein, "up and down direction" and "left and right direction" correspond to the up and down direction and left and right direction in the figures, respectively. In a preferred embodiment, the downward vertical direction (i.e., the direction in which gravity acts) can be considered as the "downward direction," and the opposite direction as the "upward direction."

[0013] The various numerical ranges referred to herein are intended to include the lower and upper numerical values ​​themselves. That is, for example, a numerical range of 1 to 10 can be interpreted as including both the lower limit value of "1" and the upper limit value of "10".

[0014] [Basic configuration of a secondary battery] First, the basic structure of a secondary battery will be explained using Figure 1. The secondary battery 1000 has a structure in which an electrode assembly 100 and an electrolyte 20 are housed and sealed inside a predetermined housing 500. The electrode assembly 100 may include a positive electrode 10A, a negative electrode 10B, and a separator 50 placed between the positive electrode 10A and the negative electrode 10B. The electrode assembly 100 may be a stacked electrode assembly or a wound (jelly roll) electrode assembly. A stacked electrode assembly has multiple electrode constituent layers, including a positive electrode, a negative electrode, and a separator, stacked on top of each other. A wound electrode assembly has electrode constituent layers, including a positive electrode, a negative electrode, and a separator, wound around each other.

[0015] (Positive electrode / Negative electrode) The positive electrode 10A is composed of at least a positive electrode material layer 12A and a positive electrode current collector 11A (see Figure 5). In the positive electrode, the positive electrode material layer 12A is provided on at least one side of the positive electrode current collector 11A. The positive electrode material layer 12A contains a positive electrode active material as an electrode active material. For example, each of the multiple positive electrodes 10A in the battery assembly 100 may have the positive electrode material layer 12A provided on both sides of the positive electrode current collector 11A, or it may have the positive electrode material layer 12A provided on only one side of the positive electrode current collector 11A.

[0016] The negative electrode 10B is composed of at least a negative electrode material layer 12B and a negative electrode current collector 11B (see Figure 5). In the negative electrode 10B, the negative electrode material layer 12B is provided on at least one side of the negative electrode current collector 11B. The negative electrode material layer 12B contains a negative electrode active material as an electrode active material. For example, each of the multiple negative electrodes 10B in the battery assembly 100 may have the negative electrode material layer 12B provided on both sides of the negative electrode current collector 11B, or it may have the negative electrode material layer 12B provided on only one side of the negative electrode current collector 11B.

[0017] The electrode active materials contained in the positive electrode 10A and the negative electrode 10B, that is, the positive electrode active material and the negative electrode active material, respectively, are materials that are directly involved in the transfer of electrons in a secondary battery and are the main materials of the positive and negative electrodes that are responsible for charging and discharging, i.e., the battery reaction. More specifically, ions are brought into the electrolyte due to the "positive electrode active material contained in the positive electrode material layer" and the "negative electrode active material contained in the negative electrode material layer," and these ions move between the positive and negative electrodes to transfer electrons and perform charging and discharging. The positive electrode material layer 12A and the negative electrode material layer 12B may be layers that are particularly capable of intercalating and releasing lithium ions. In other words, the secondary battery according to this disclosure may be a non-aqueous electrolyte secondary battery in which lithium ions move between the positive and negative electrodes via a non-aqueous electrolyte to perform charging and discharging of the battery. When lithium ions are involved in charging and discharging, the secondary battery according to this disclosure corresponds to a so-called "lithium-ion battery" and has layers capable of intercalating and releasing lithium ions as the positive electrode and negative electrode.

[0018] In the context of lithium-ion batteries, the positive electrode active material may be a material that facilitates the intercalation and deintercalation of lithium ions. In other words, the positive electrode layer may contain one or more types of positive electrode materials capable of intercalating and deintercalating lithium. From this perspective, the positive electrode active material may be, for example, a lithium-containing compound. The type of lithium-containing compound is not particularly limited, but examples include lithium-containing composite oxides and lithium-containing phosphate compounds, because they easily provide high energy density.

[0019] Lithium-containing composite oxides are a general term for oxides containing lithium and one or more other elements (elements other than lithium) as constituent elements, and may have any crystal structure such as a layered rock salt type or a spinel type, for example. Lithium-containing phosphate compounds are a general term for phosphate compounds containing lithium and one or more other elements as constituent elements, and may have a crystal structure such as an olivine type, for example. The type of the other element is not particularly limited as long as it is any one or more of arbitrary elements. Among them, the other element is preferably any one or more of the elements belonging to Groups 2 to 15 in the long-period type periodic table. More specifically, the other element is, for example, nickel (Ni), cobalt (Co), manganese (Mn), iron (Fe), etc. This is because a high voltage can be easily obtained by these additive elements.

[0020] The lithium-containing composite oxide having a layered rock salt type crystal structure may be, for example, a compound represented by each of the following formulas (1) to (3). Li a Mn (1-b-c) Ni b M11 c O (2-d) F e ···(1) (M11 is at least one of cobalt (Co), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper (Cu), zinc (Zn), zirconium (Zr), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), and tungsten (W). a to e satisfy 0.8 ≦ a ≦ 1.2, 0 < b < 0.5, 0 ≦ c ≦ 0.5, (b + c) < 1, -0.1 ≦ d ≦ 0.2, and 0 ≦ e ≦ 0.1. However, the composition of lithium varies depending on the charge-discharge state, and a is the value in the fully discharged state.) Li a Ni (1-b) M12 b O (2-c) F d ···(2) (M12 is at least one of the following: cobalt (Co), manganese (Mn), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), and tungsten (W). a~d satisfy 0.8≦a≦1.2, 0.005≦b≦0.5, -0.1≦c≦0.2, and 0≦d≦0.1. However, the lithium composition differs depending on the charge / discharge state, and a is the value in the fully discharged state.) Li a Co (1-b) M13 b O (2-c) F d ...(3) (M13 is at least one of the following: nickel (Ni), manganese (Mn), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), and tungsten (W). a~d satisfy 0.8≦a≦1.2, 0≦b<0.5, -0.1≦c≦0.2, and 0≦d≦0.1. However, the lithium composition differs depending on the charge / discharge state, and a is the value in the fully discharged state.) Specific examples of lithium-containing composite oxides having a layered rock salt-type crystal structure include LiNiO2, LiCoO2, and LiCo 0.98 Al 0.01 Mg 0.01 O2, LiLiLi 0.5 Co 0.2 Mn 0.3 O2, LiLiLi 0.8 Co 0.15 Al 0.05 O2, LiLiLi 0.33 Co 0.33 Mn 0.33 O2, Li 1.2 Mn 0.52 Co 0.175 Ni 0.1 O2 and Li 1.15 (Mn0.65 Ni 0.22 Co 0.13 Examples include O2. Furthermore, when a lithium-containing composite oxide having a layered rock salt-type crystalline structure contains nickel, cobalt, manganese, and aluminum as constituent elements, it is preferable that the atomic ratio of nickel be 50 atomic percent or more. This is because it is easier to obtain a high energy density.

[0021] A lithium-containing composite oxide having a spinel-type crystal structure may be, for example, a compound represented by the following formula (4). Li a Mn (2-b) M14 b O c F d ...(4) (M14 is at least one of the following: cobalt (Co), nickel (Ni), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), and tungsten (W). a~d satisfy 0.9≦a≦1.1, 0≦b≦0.6, 3.7≦c≦4.1, and 0≦d≦0.1. However, the lithium composition differs depending on the charge / discharge state, and a is the value in the fully discharged state.) Specific examples of lithium-containing composite oxides having a spinel-type crystal structure include LiMn2O4, for example.

[0022] Lithium-containing phosphate compounds having an olivine-type crystal structure are, for example, compounds represented by the following formula (5). Li a M15PO4···(5) (M15 is at least one of the following: cobalt (Co), manganese (Mn), iron (Fe), nickel (Ni), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), niobium (Nb), copper (Cu), zinc (Zn), molybdenum (Mo), calcium (Ca), strontium (Sr), tungsten (W), and zirconium (Zr). a satisfies 0.9 ≤ a ≤ 1.1. However, the composition of lithium varies depending on the charge / discharge state, and a is the value for the fully discharged state.) Specific examples of lithium-containing phosphate compounds having an olivine-type crystal structure include LiFePO4, LiMnPO4, and LiFe 0.5 Mn 0.5 PO4 and LiFe 0.3 Mn 0.7 It could be PO4, for example.

[0023] The lithium-containing composite oxide may also be a compound represented by the following formula (6). (Li2MnO3) x (LiMnO2) 1-x ...(6) (x satisfies 0 ≤ x ≤ 1. However, the lithium composition differs depending on the charge / discharge state, and x is the value for the fully discharged state.)

[0024] In addition, the positive electrode material may be one or more of the following: oxides, disulfides, chalcogenides, and conductive polymers. Oxides may be titanium oxide, vanadium oxide, and manganese dioxide, for example. Disulfides may be titanium disulfide and molybdenum sulfide, for example. Chalcogenides may be niobium selenide, for example. Conductive polymers may be sulfur, polyaniline, and polythiophene, for example. However, the positive electrode material is not particularly limited and may be other materials not listed above.

[0025] The positive electrode material layer 12A may contain a binder. Furthermore, the positive electrode material layer may contain a positive electrode conductive agent to facilitate the transfer of electrons that drive the battery reaction. The positive electrode binder may contain one or more of the following: synthetic rubber and polymer compounds. Examples of synthetic rubber include styrene-butadiene rubber, fluorine-based rubber, and ethylene-propylenediene. Examples of polymer compounds include polyvinylidene fluoride and polyimide. The positive electrode conductive agent may contain one or more of the following: carbon materials, etc. Examples of carbon materials include graphite, carbon black, acetylene black, and Ketjen black. However, the positive electrode conductive agent may also be any conductive material, such as metal materials and conductive polymers.

[0026] Similarly, the negative electrode active material of the negative electrode layer 12B may be a material that contributes to the intercalation and deintercalation of lithium ions. In other words, the negative electrode layer may contain one or more types of negative electrode materials capable of intercalating and deintercalating lithium. From this perspective, the negative electrode active material may be, for example, various carbon materials, metallic materials, and / or other materials.

[0027] When carbon materials are used as the negative electrode active material, the change in crystal structure during lithium absorption and release is very small, making it easy to stably obtain a high energy density. In addition, since carbon materials also function as negative electrode conductive agents, the conductivity of the negative electrode layer is easily improved.

[0028] Specific carbon materials include, for example, easily graphitizable carbon, poorly graphitizable carbon, and / or graphite. More specifically, the carbon material may be, for example, pyrolytic carbons, cokes, glassy carbon fibers, calcined organic polymer compounds, activated carbon, and carbon blacks. Cokes may include pitch coke, needle coke, and petroleum coke. Calcined organic polymer compounds are, for example, substances obtained by calcining (carbonizing) polymer compounds such as phenolic resins and furan resins at an appropriate temperature. In addition, the carbon material may be low-crystalline carbon heat-treated at a temperature of about 1000°C or lower, or amorphous carbon. The shape of the carbon material is not particularly limited and may be at least one of fibrous, spherical, granular, and flaky.

[0029] "Metallic materials" used as negative electrode active materials are a general term for materials that contain one or more metallic elements and metalloid elements as constituent elements. When carbon materials are used as negative electrode active materials, high energy density is easily obtained. Metallic materials may be elements, alloys, compounds, two or more of these, or materials that contain at least one or two or more of these phases. However, alloys may include materials consisting of two or more metallic elements, as well as materials containing one or more metallic elements and one or more metalloid elements. Furthermore, alloys may contain nonmetallic elements. The structure of these metallic materials may be, for example, solid solutions, eutectic (eutectic mixtures), intermetallic compounds, and coexistences of two or more of these.

[0030] Such metallic and metalloid elements may be, for example, one or more metallic and metalloid elements capable of forming alloys with lithium. Specifically, metallic and metalloid elements may be, for example, magnesium (Mg), boron (B), aluminum (Al), gallium (Ga), indium (In), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), bismuth (Bi), cadmium (Cd), silver (Ag), zinc (Zn), hafnium (Hf), zirconium, yttrium (Y), palladium (Pd), and / or platinum (Pt).

[0031] In one preferred embodiment, the metallic elements are silicon and tin. This is because these metallic elements have excellent ability to intercalate and deintercalate lithium, making it easier to obtain higher energy densities. A material containing silicon as a constituent element may be elemental silicon, an alloy of silicon, a compound of silicon, two or more selected from these, or a material containing at least one or more of these phases. Similarly, a material containing tin as a constituent element may be elemental tin, an alloy of tin, a compound of tin, two or more of these, or a material containing at least one or more of these phases.

[0032] As the "single substance" described in this specification is a single substance in a general sense, it may contain trace amounts of impurities. That is, the purity of the single substance is not necessarily limited to 100%. An alloy of silicon may contain, for example, any one or more of tin, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony, and chromium as constituent elements other than silicon. A compound of silicon may contain, for example, any one or more of carbon and oxygen as constituent elements other than silicon. Note that a compound of silicon may also contain any one or more of the series of elements described for an alloy of silicon as constituent elements other than silicon.

[0033] Specific examples of an alloy of silicon and a compound of silicon include SiB4, SiB6, MgSi, Ni2Si, TiSi2, MoSi2, CoSi2, NiSi2, CaSi2, CrSi2, Cu5Si, FeSi2, MnSi2, NbSi2, TaSi2, VSi2, WSi2, ZnSi2, SiC, Si3N4, Si2N2O, SiO v (0 < v ≦ 2), and / or LiSiO, etc. can be cited. Note that for SiO v v therein may be 0.2 < v < 1.4. An alloy of tin may contain, for example, any one or more of silicon, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony, and chromium as constituent elements other than tin. A compound of tin may contain, for example, any one or more of carbon and oxygen as constituent elements other than tin. Note that a compound of tin may also contain any one or more of the series of elements described for an alloy of tin as constituent elements other than tin. Specific examples of an alloy of tin and a compound of tin include SnO w(0 < w ≤ 2), SnSiO3, LiSnO, and / or Mg2Sn, etc. can be mentioned. In particular, a material containing tin as a constituent element may be, for example, a material (tin-containing material) containing a second constituent element and a third constituent element together with tin which is the first constituent element. The second constituent element may be, for example, any one or more of cobalt, iron, magnesium, titanium, vanadium, chromium, manganese, nickel, copper, zinc, gallium, zirconium, niobium, molybdenum, silver, indium, cesium (Ce), hafnium (Hf), tantalum, tungsten, bismuth, and silicon. The third constituent element may be, for example, any one or more of boron, carbon, aluminum, and phosphorus. This is because high battery capacity, excellent cycle characteristics, etc. are easily obtained by these elements.

[0034] Among them, the tin-containing material may be a material (tin-cobalt-carbon-containing material) containing tin, cobalt, and carbon as constituent elements. This is because high energy density is easily obtained by these materials. In the tin-cobalt-carbon-containing material, at least a part of the carbon which is a constituent element may be bonded to a metal element or a metalloid element which is another constituent element. This is because aggregation and crystallization of tin, etc. are easily suppressed in this way. Such a tin-cobalt-carbon-containing material is not limited to a material (SnCoC) whose constituent elements are only tin, cobalt, and carbon. This tin-cobalt-carbon-containing material may contain, for example, any one or more of silicon, iron, nickel, chromium, indium, niobium, germanium, titanium, molybdenum, aluminum, phosphorus, gallium, and bismuth, etc. as constituent elements in addition to tin, cobalt, and carbon. In addition to the tin-cobalt-carbon-containing material, a material (tin-cobalt-iron-carbon-containing material) containing tin, cobalt, iron, and carbon as constituent elements may also be used.

[0035] In addition, the negative electrode material may be one or more of the following: metal oxides and polymer compounds. Examples of metal oxides include iron oxide, ruthenium oxide, and molybdenum oxide. Examples of polymer compounds include polyacetylene, polyaniline, and polypyrrole.

[0036] The negative electrode material layer 12B may contain a binder. Furthermore, a negative electrode conductive agent may be included in the negative electrode material layer to facilitate the transfer of electrons that drive the battery reaction. The binder that may be included in the negative electrode material layer is not particularly limited, but at least one selected from the group consisting of styrene-butadiene rubber, polyacrylic acid, polyvinylidene fluoride, polyimide resins, and polyamide-imide resins can be mentioned. The negative electrode conductive agent that may be included in the negative electrode material layer is not particularly limited, but at least one selected from the group consisting of carbon black such as thermal black, furnace black, channel black, Ketjen black, and acetylene black, carbon fibers such as graphite, carbon nanotubes, and vapor-grown carbon fibers, metal powders such as copper, nickel, aluminum, and silver, and polyphenylene derivatives can be mentioned. The negative electrode material layer may also contain components resulting from the thickening agent components (e.g., carboxymethylcellulose) used during battery fabrication.

[0037] The positive electrode current collector 11A and the negative electrode current collector 11B used in the positive electrode 10A and negative electrode 10B are components that contribute to collecting and supplying electrons generated in the electrode active material due to the battery reaction. Such electrode current collectors may be sheet-shaped metal members. Furthermore, the electrode current collectors may be single-layered or multi-layered. Moreover, the electrode current collectors may have a porous or perforated form. For example, the current collector may be metal foil, perforated metal, mesh, or expanded metal. The positive electrode current collector used in the positive electrode may consist of metal foil containing at least one selected from the group consisting of aluminum, nickel, and stainless steel, for example. On the other hand, the negative electrode current collector used in the negative electrode may consist of metal foil containing at least one selected from the group consisting of copper, aluminum, nickel, and stainless steel, for example.

[0038] (Separator) The separator 50, provided between the positive electrode 10A and the negative electrode 10B, is a component provided from the viewpoint of preventing short circuits caused by contact between the positive and negative electrodes and maintaining the electrolyte. In other words, the separator 50 is a component that isolates the positive electrode 10A and the negative electrode 10B, and allows ions (e.g., lithium ions) to pass through while preventing short circuits of current caused by contact between the two electrodes. For example, the separator 50 may be a porous or microporous insulating material, and may have a film form due to its small thickness.

[0039] The separator 50 may be one or more types of porous membranes, such as synthetic resins and / or ceramics, or it may be a laminated film of two or more types of porous membranes. Examples of synthetic resins used in the separator 50 include polytetrafluoroethylene, polypropylene, and polyethylene. For example, the separator 50 may include a porous membrane (base layer) and a polymer compound layer provided on one or both sides of the base layer. This improves the adhesion of the separator 50 to the positive electrode and the adhesion of the separator 50 to the negative electrode, thereby making it easier to suppress distortion of the wound electrode body. The polymer compound layer may include one or more types of polymer compounds, such as polyvinylidene fluoride. This provides excellent physical strength and makes it easier to achieve electrochemical stability. The polymer compound layer may also include one or more types of insulating particles, such as inorganic particles. Examples of inorganic particles may include aluminum oxide and / or aluminum nitride. In this disclosure, the separator 50 should not be particularly restricted by its name, and may be a solid electrolyte, a gel electrolyte, and / or insulating inorganic particles having similar functions.

[0040] (electrolyte) The electrolyte 20 that can be used in the secondary battery of this disclosure may be a so-called “non-aqueous” electrolyte. Typically, the electrolyte solution comprises a solvent and an electrolyte salt. The electrolyte solution may further contain one or more of the other materials, such as additives. In one preferred embodiment, the separator may be impregnated with the electrolyte solution, and furthermore, the positive electrode and / or negative electrode may also be impregnated with the electrolyte solution.

[0041] The solvent may contain one or more non-aqueous solvents, such as organic solvents. An electrolyte containing a non-aqueous solvent can be a so-called non-aqueous electrolyte. Examples of non-aqueous solvents include cyclic carbonate esters, linear carbonate esters, lactones, linear carboxylic acid esters, and / or nitriles (e.g., mononitriles). This makes it easier to obtain better battery capacity, cycle characteristics, and / or storage characteristics. Examples of cyclic carbonate esters include ethylene carbonate, propylene carbonate, and / or butylene carbonate. Examples of linear carbonate esters include dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, and / or methylpropyl carbonate. Examples of lactones include γ-butyrolactone and / or γ-valerolactone. Examples of linear carboxylic acid esters include methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, methyl isobutyrate, methyl trimethylacetate, and / or trimethylethyl acetate. The nitrile may be, for example, acetonitrile, methoxyacetonitrile and / or 3-methoxypropionitrile. In addition, the non-aqueous solvent may be, for example, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,3-dioxane, 1,4-dioxane, N,N-dimethylformamide, N-methylpyrrolidinone, N-methyloxazolidinone, N,N'-dimethylimidazolidinone, nitromethane, nitroethane, sulfolane, trimethyl phosphate and / or dimethyl sulfoxide.

[0042] Among these, the non-aqueous solvent preferably contains one or more of the following: ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethylmethyl carbonate. This is because it is easier to obtain higher battery capacity, better cycle characteristics, and / or better storage characteristics. Furthermore, the non-aqueous solvent may be, for example, unsaturated cyclic carbonate esters, halogenated carbonate esters, sulfonic acid esters, acid anhydrides, dicyano compounds (dinitrile compounds), diisocyanate compounds, phosphate esters, and / or chain compounds having carbon-carbon triple bonds. This makes it easier to improve the chemical stability of the electrolyte. Here, "unsaturated cyclic carbonate ester" refers to a cyclic carbonate ester having one or more unsaturated bonds (carbon-carbon double bonds or carbon-carbon triple bonds). Examples of such unsaturated cyclic carbonate esters include vinylene carbonate, vinylethylene carbonate, and / or methyleneethylene carbonate. "Halogenated carbonate ester" refers to a cyclic or chain carbonate ester containing one or more halogen elements as constituent elements. When a halogenated carbonate ester contains two or more halogens as constituent elements, the types of those two or more halogens may be just one type or two or more types.

[0043] Examples of cyclic halogenated carbonate esters include 4-fluoro-1,3-dioxolan-2-one and / or 4,5-difluoro-1,3-dioxolan-2-one. Examples of linear halogenated carbonate esters may be fluoromethylmethyl carbonate, bis(fluoromethyl) carbonate and / or difluoromethylmethyl carbonate. Examples of sulfonic acid esters may be monosulfonic acid esters and / or disulfonic acid esters. Monosulfonic acid esters may be cyclic monosulfonic acid esters or linear monosulfonic acid esters. Examples of cyclic monosulfonic acid esters may be sultones such as 1,3-propanesultone and / or 1,3-propensultone.

[0044] A linear monosulfonic acid ester is, for example, a compound obtained by cleaving a cyclic monosulfonic acid ester. A disulfonic acid ester may be a cyclic disulfonic acid ester or a linear disulfonic acid ester. An acid anhydride may be, for example, a carboxylic acid anhydride, a disulfonic acid anhydride, and / or a carboxylic acid sulfonic acid anhydride. A carboxylic acid anhydride may be, for example, succinic anhydride, glutaric anhydride, and / or maleic anhydride. A disulfonic acid anhydride may be, for example, ethanedisulfonic anhydride and / or propanedisulfonic anhydride. A carboxylic acid sulfonic acid anhydride may be, for example, sulfobenzoic anhydride, sulfopropionic anhydride, and / or sulfobutyric anhydride. A dinitrile compound is, for example, a compound represented as NC-R1-CN (where R1 is either an alkylene group or an arylene group). This dinitrile compound may be, for example, succinonitrile (NC-C2H4-CN), glutalonitrile (NC-C3H6-CN), adiponitrile (NC-C4H8-CN), and phthalonitrile (NC-C6H4-CN). The diisocyanate compound is, for example, a compound represented as OCN-R2-NCO (where R2 is either an alkylene group or an arylene group). This diisocyanate compound is, for example, hexamethylene diisocyanate (OCN-C6H 12 It may be -NCO), etc. Phosphate esters may be, for example, trimethyl phosphate and triethyl phosphate. A chain compound having a carbon-carbon triple bond is a chain compound having one or more carbon-carbon triple bonds (-C≡C-). This chain compound having a carbon-carbon triple bond may be, for example, propargylmethyl carbonate (CH≡C-CH2-OC(=O)-O-CH3) and propargyl methylsulfonic acid (CH≡C-CH2-OS(=O)2-CH3).

[0045] The electrolyte salts contained in the electrolyte solution may include one or more types of salts, such as lithium salts. The electrolyte salts may also include salts other than lithium salts. Such non-lithium salts may be salts of light metals other than lithium, for example. Examples of lithium salts include lithium hexafluoride phosphate (LiPF6), lithium tetraborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoride arsenate (LiAsF6), lithium tetraphenylborate (LiB(C6H5)4), lithium methanesulfonate (LiCH3SO3), lithium trifluoromethanesulfonate (LiCF3SO3), lithium tetrachloroaluminate (LiAlCl4), dilithium hexafluorosilicate (Li2SiF6), lithium chloride (LiCl), and / or lithium bromide (LiBr). This is because it is easier to obtain better battery capacity, cycle characteristics, and / or storage characteristics. Among these, it may be one or more of lithium hexafluoride phosphate, lithium tetrafluoroborate, lithium perchlorate, and lithium hexafluoride arsenate.

[0046] (Detention area) The housing 500 used in a secondary battery corresponds to a component that encloses a battery assembly 100, which is made up of laminated electrode layers including a positive electrode 10A, a negative electrode 10B, and a separator 50. Such a housing 500 can also be called, for example, a battery can. As an example, the housing 500 broadly comprises an outer casing 200 having an opening at one end, a sealing body 300 that seals the opening, and a gasket 400 that functions as a sealing material and insulating material between the outer casing 200 and the sealing body 300. That is, in this disclosure, the gasket 400 may be an insulating sealing member.

[0047] In this disclosure, the form of the housing 500 (corresponding to the battery can) can be cylindrical, button-shaped, or coin-shaped. That is, the secondary battery of this disclosure may be a cylindrical, button-shaped, or coin-shaped secondary battery.

[0048] The gasket 400 is located between the inner surface of one end of the side wall portion 220 of the outer casing 200 and the outer edge of the sealing body 300. The gasket 400 may be an insulating resin material. In this case, for example, a propylene-based resin material, an acrylic-based resin material, a silicone-based resin material, a urethane-based resin material, etc., can be used as the gasket 400.

[0049] The outer casing 200 comprises a side wall portion 220 that constitutes or forms the above-mentioned opening, and a bottom portion 210 continuous with the side wall portion 220. That is, the outer casing 200 may have a hollow structure. The sealing body 300 may have a positive terminal 310 that may be located at the top of the battery can, and a sealing plate 320 provided inside the positive terminal 310 so as to be in contact with the terminal. This sealing plate 320 may function as a safety valve.

[0050] In one example, the side wall portion 220 of the outer casing 200 may have a crimped structure in which it is crimped to the outer edge of the sealing body 300 via a gasket 400. In this case, the interposed gasket 400 may be positioned to sandwich the outer edge of the sealing body 300, specifically the positive terminal 310, and the sealing plate 320, specifically the first metal member 330 which will be described later.

[0051] Furthermore, the outer casing 200 can function as a negative electrode terminal itself. The negative electrode 10B can be connected to this outer casing 200 via a conductive member on the negative electrode side. The constituent material of such a conductive member may include, for example, nickel.

[0052] The outer casing 200 may be a conductive metal component. For example, the outer casing 200 may include iron, copper, nickel, stainless steel, iron alloys, copper alloys, and nickel alloys. As stainless steel, for example, SUS304 and SUS316 can be used.

[0053] The side wall portion 220 of the outer casing 200 is provided with a beading portion 221 that is continuous along its outer circumference and recessed toward the inside of the battery. Therefore, in this specification, this beading portion 221 may be referred to as a recess, groove, constriction, or narrowing portion that recesses toward the inside of the battery.

[0054] The beading portion 221 includes an inwardly curved portion 225. The beading portion 221 also has a gasket support wall portion 223 that extends inward from the recess start point 224 toward the inside of the battery and is capable of supporting the gasket 400.

[0055] In one example, the gasket support wall portion 223 may constitute part of the inner curved portion 225 of the beading portion 221. The presence of such gasket support wall portion 223 supports the gasket 400, thereby allowing the sealing body 300 to be suitably supported by the gasket 400.

[0056] The following describes an exemplary configuration of the sealing plate 320. The sealing plate 320 may comprise a first metal member 330, a second metal member 350, and an insulating member 340 located between the first metal member 330 and the second metal member 350, which are stacked sequentially in a downward or inward direction relative to the installation location of the positive terminal 310 located on the upper or outer side. Preferably, the insulating member 340 may be located between the first metal member 330 and the second metal member 350 as an adhesive member.

[0057] In one example, the first metal member 330 described above is displaceable so as to be deformable and / or ruptureable in response to the internal pressure inside the battery can. The second metal member 350 is also displaceable in response to an increase in the internal pressure inside the battery can. The second metal member 350 and the positive electrode 10A of the electrode assembly 100 can be connected via the conductive member 360 on the positive electrode side.

[0058] The conductive member 360 may be, for example, a current collector lead or a tab. The conductive member 360 may include one or more metallic materials such as aluminum, titanium, platinum, and gold.

[0059] The first metal member 330 may include one or more metallic materials such as aluminum, titanium, platinum, and gold. The planar shape of the first metal member 330, when viewed from the longitudinal direction of the exterior body 200, may be, for example, circular, polygonal, or other shapes. The first metal member 330 may be plate-shaped. The first metal member 330 may also have a plurality of grooves 331 at predetermined locations on its inner main surface.

[0060] The second metal member 350 is positioned inside the battery relative to the first metal member 330 via an insulating member 340. The second metal member 350 is provided with a groove 351 for interrupting the current path in the event of a battery malfunction. The groove 351 may be provided, for example, to surround the central axis of the battery. The conductive member 360 may be connected to the outer peripheral region 353 of the second metal member 350, which is outside the groove 351. In addition to the groove 351, the second metal member 350 may also have an opening 354. Such an opening 354 may be used as an opening for releasing gas from inside the battery case to the outside.

[0061] Figure 1 shows the configuration under normal conditions when no gas or other substances are generated inside the battery can. In this configuration, the central region 352 of the second metal member 350, located inside the groove 351, is in contact with the first metal member 330. Furthermore, as described above, the first metal member 330 is in contact with the positive electrode terminal 310. As a result, the positive electrode 10A inside the battery can be electrically connected to the positive electrode terminal 310.

[0062] The second metal member 350, like the first metal member 330, may contain one or more metallic materials such as aluminum, titanium, platinum, and gold. The second metal member 350 may have the same material as the first metal member 330, or it may have a different material. The planar shape of the outer edge of the second metal member 350, when viewed from the longitudinal direction of the exterior body 200, may be, for example, circular, polygonal, or other shapes. The second metal member 350 may be plate-shaped.

[0063] The planar shape of the insulating member 340 may be a ring shape with an open central portion. The insulating member 340 may be plate-shaped. The insulating member 340 may be an insulating resin member. In this case, the insulating member 340 may be composed of a thermosetting resin, a thermoplastic resin, and / or a UV-curable resin. For example, the insulating member 340 may be a member containing an insulating resin adhesive. Examples of such resin adhesives include acrylic resin adhesives, silicone resin adhesives, urethane resin adhesives, and the like.

[0064] The positive electrode terminal 310 may be a conductive metal component. For example, the positive electrode terminal 310 may contain one or more of the following metal materials: iron, aluminum, titanium, platinum, gold, etc. The positive electrode terminal 310 may have multiple openings. These multiple openings can contribute to the release of leaked gas to the outside of the battery case when gas generated inside the battery case leaks out through the rupture of the first metal component 330.

[0065] If a battery is overcharged, gas will be generated inside the battery. This gas can cause the pressure inside the battery case to rise, potentially leading to the battery case rupturing. By incorporating the safety valve configuration described above, if the internal pressure of the battery case rises, a portion of the sealing plate 320 that constitutes the safety valve will be blocked and opened, thereby interrupting the battery's current path and releasing the gas. This prevents the battery case from rupturing.

[0066] Specifically, when gas is generated inside the battery case due to side reactions such as the decomposition reaction of the electrolyte caused by overcharging of the battery, the gas accumulates inside the battery case, and the internal pressure rises. When the internal pressure of the battery case exceeds a predetermined pressure, the central region of the first metal member 330 is pushed up and displaced outward along the longitudinal axis of the battery. Along with this displacement, the central region 352 of the second metal member 350 is also pushed up and breaks starting from the groove 351 provided in the second metal member 350. Breakage here means that the connection is completely severed.

[0067] Such fracture can divide the second metal member 350 into a central region 352 connected to the first metal member 330 and an outer peripheral region 353 connected to the conductive member 360. As a result, the current path between the positive electrode terminal 310 and the battery assembly 100 is interrupted, making it possible to interrupt the battery current in the event of an abnormal rise in internal pressure.

[0068] After the above-described shutoff mechanism is activated, if the displacement of the first metal member 330 progresses further due to the increase in internal pressure, it may crack or break starting from the groove 331 provided in the first metal member 330. When the first metal member 330 cracks, gas inside the battery can be released to the outside through the cracked portion and the opening of the positive electrode terminal 310. This reduces the internal pressure inside the battery can.

[0069] The following describes the features of this disclosure. This disclosure is characterized by the configuration of the beading portion 221 of the side wall portion 220 of the exterior body 200 described above.

[0070] Specifically, as shown in Figure 2, in a cross-sectional view, the present disclosure is characterized in that the smallest R portion 222 of the inner curved portion 225 of the beading portion 221, where the radius of curvature is smallest, is located above the recess start point 224 of the gasket support wall portion 223.

[0071] According to these features, in a cross-sectional view, the gasket support wall portion 223 of the beading portion 221 may have a structure that slopes diagonally upward from the recess start point 224 toward the minimum radius portion 222. As a result, in a cross-sectional view, the minimum radius portion 222 may be configured to partially bite into the gasket 400.

[0072] This configuration makes it possible to make the thickness dimension of a predetermined part of the gasket 400 that contacts the minimum R portion 222 smaller than the thickness dimension of other parts. This supports the sealing plate 320 of the sealing body 300, specifically the first metal member 330 of the sealing plate 320, and suppresses the flow of the constituent resin member at the predetermined part of the gasket 400.

[0073] As a result, the compressive stress of the gasket 400 can be maintained, and the sealing performance of the gasket 400 between the outer casing 200 and the sealing body 300 can be further improved. Therefore, leakage of liquid from the inside to the outside of the battery and ingress of moisture from the outside to the inside of the battery can be suitably avoided, and the reliability of the secondary battery 1000 of this disclosure can be ensured over a long period of time. In other words, the secondary battery 1000 of this disclosure can ensure long-term reliability as a "sealed secondary battery". In addition, the insulation between the outer casing 200, which functions as the negative electrode terminal, and the positive electrode terminal 310, which is a component of the sealing body 300, can be suitably ensured.

[0074] Furthermore, from the viewpoint of more effectively suppressing the flow of the constituent resin members at the predetermined locations of the gasket 400, it is preferable that the curvature angle θ (see Figure 2) of the minimum R portion 222 in cross-sectional view is 90 degrees or less. In addition, in order to achieve the same viewpoint, the side wall portion 220 of the exterior body 200 equipped with the beading portion 221 is required to have a strength of a certain level or higher. In order to ensure such strength, it is preferable that the thickness of the side wall portion 220 of the exterior body 200 is 0.1 mm or more.

[0075] The following describes a method for manufacturing a secondary battery according to one embodiment of this disclosure.

[0076] First, a positive electrode mixture containing the positive electrode active material is formed, and the positive electrode mixture is dispersed in an organic solvent to obtain a paste-like positive electrode mixture slurry. The positive electrode mixture slurry is applied to the main surface (one main surface or both main surfaces) of a metal foil to be used as the positive electrode current collector, and the slurry is dried to produce the positive electrode. After that, the positive electrode is pressurized using a roll press machine.

[0077] Similarly, a negative electrode mixture containing a negative electrode active material is formed, and the negative electrode mixture is dispersed in an organic solvent to obtain a paste-like negative electrode mixture slurry. The negative electrode mixture slurry is applied to the main surface (one main surface or both main surfaces) of a metal foil to be used as a negative electrode current collector, and the negative electrode mixture slurry is dried to produce a negative electrode. After that, the negative electrode is pressurized using a roll press machine.

[0078] Subsequently, a positive electrode lead is connected to a metal foil acting as a positive electrode current collector, and a negative electrode lead is connected to a metal foil acting as a negative electrode current collector. Next, the positive electrode 10A and the negative electrode 10B are stacked via a separator 50, and the positive electrode 10A, the negative electrode 10B, and the separator 50 are wound or stacked in multiple layers to form an electrode assembly 100. Then, the electrode assembly 100 is housed inside the outer casing 200, and one end of the positive electrode lead 360 is connected to the second metal member 350 of the sealing plate 320 by welding, and one end of the negative electrode lead is connected to the inner surface of the outer casing 200 in the same manner. Next, an electrolyte is injected into the outer casing 200, impregnating the electrode assembly with the electrolyte.

[0079] Next, with the gasket 400 provided so as to sandwich both sides of the outer edge of the sealing body 300 (positive terminal 310 and sealing plate 320 connected to the positive terminal 310), the side wall portion 220 of the outer casing 200 is crimped using a crimping member so that one end of the side wall portion 220 of the outer casing 200 is positioned above the outer edge of the sealing body 300.

[0080] Along with this, the following process is carried out. Specifically, the exterior body 200 having the beading section 221 having the characteristic configuration described above is manufactured, for example, through the following process (a) or (b) (see Figure 4).

[0081] Process (a) Before processing, the side wall portion 220, which is generally flat in cross-sectional view, is pressed inward at an upward angle using the jig M1. This pressing creates an inner recess 221a at a predetermined location on the side wall portion 220, which is recessed inward at an upward angle.

[0082] Next, the inner recess 221a is pressed using the metal member M2 having an inclined surface to form a minimum radius R portion 222 at a predetermined location in the inner recess 221a (corresponding to one end of the gasket support wall portion 223 when the battery is manufactured), where the radius of curvature is minimized.

[0083] • Process (b) Before processing, the side wall portion 220, which is generally flat in cross-sectional view, is pressed inward in a roughly horizontal direction using the jig M3. This pressing creates an inner recess 221b at a predetermined location on the side wall portion 220, which is recessed inward in a roughly horizontal direction.

[0084] Next, two metal members M4 and M5, which have mutually inclined surfaces, are used to press a predetermined location in the inner recess 221b (corresponding to the gasket support wall portion 223 when the battery is manufactured) to tilt the predetermined location diagonally upward toward the inside, and a minimum radius R portion 222 with the smallest radius of curvature is formed at one end of this inclined portion.

[0085] The two metal members M4 and M5 are positioned such that a predetermined portion of the inner recess 221b is sandwiched between the inclined surface of metal member M4 and the inclined surface of metal member M5.

[0086] Based on the above, a secondary battery 1000 can be manufactured, which has an outer casing 200 having a beading section 221 with a distinctive configuration.

[0087] The embodiments of this disclosure have been described above, but these are merely typical examples. Those skilled in the art will readily understand that this disclosure is not limited thereto, and various embodiments are conceivable without altering the essence of this disclosure. [Examples]

[0088] The following describes some examples.

[0089] Examples First, as part of the process for manufacturing the positive electrode, a positive electrode mixture containing the positive electrode active material was formed, and the positive electrode mixture was dispersed in an organic solvent to obtain a paste-like positive electrode mixture slurry. The positive electrode mixture slurry was applied to the main surface of a metal foil to be used as the positive electrode current collector, and the slurry was dried to manufacture the positive electrode. Subsequently, the positive electrode was pressurized using a roll press machine.

[0090] Similarly, as a process for manufacturing the negative electrode, a negative electrode mixture containing the negative electrode active material was formed, and the negative electrode mixture was dispersed in an organic solvent to obtain a paste-like negative electrode mixture slurry. The negative electrode mixture slurry was applied to the main surface of a metal foil to be used as the negative electrode current collector, and the slurry was dried to manufacture the negative electrode. Subsequently, the negative electrode was pressurized using a roll press machine.

[0091] Subsequently, a positive electrode lead was connected to a metal foil serving as the positive electrode current collector, and a negative electrode lead was connected to a metal foil serving as the negative electrode current collector. Next, the positive electrode 10A and the negative electrode 10B were stacked via a separator 50, and a wound electrode body was formed by winding the positive electrode 10A, the negative electrode 10B, and the separator 50. Next, a center pin was inserted into the winding space of the wound electrode body. Then, the wound electrode body was housed inside an outer casing 200 made of Fe material, and one end of the positive electrode lead 360 made of Al material was connected to the second metal member 350 of the sealing plate 320 by welding, and one end of the negative electrode lead made of Ni material was connected to the inner surface of the outer casing 200 in the same manner. Next, an electrolyte was injected into the outer casing 200, impregnating the wound electrode body with the electrolyte.

[0092] Next, with a gasket 400 made of polypropylene resin material placed so as to sandwich both sides of the outer edge of the sealing body 300 (positive electrode terminal 310 made of Fe material and sealing plate 320 made of Al material connected to the positive electrode terminal 310), the side wall portion 220 of the outer casing body 200 was crimped using a crimping member so that one end of the side wall portion 220 of the outer casing body 200 was positioned above the outer edge of the sealing body 300.

[0093] In conjunction with this crimping, before processing, the side wall portion 220, which is generally flat in cross-sectional view, was pressed inward at an upward angle using a jig. This pressing formed an inner recess 221a at a predetermined location on the side wall portion 220, which was recessed inward at an upward angle. Next, the inner recess 221a was pressed using a metal member M2 having an inclined surface to form a minimum radius R portion 222 at a predetermined location on the inner recess 221a (corresponding to one end of the gasket support wall portion 223) (see Figure 2).

[0094] Based on the above, a secondary battery was fabricated that includes an outer casing 200 having a beading portion 221 with a distinctive configuration. In the secondary battery of this embodiment, it was possible to suppress the flow of the constituent resin material at a predetermined location of the gasket 400 that supports the sealing plate 320 of the sealing body 300 and contacts the minimum R portion 222.

[0095] As a result, it was found that the compressive stress of the gasket 400 could be maintained, and the sealing performance of the gasket 400 between the outer casing 200 and the sealing body 300 could be further improved.

[0096] Comparative Example The comparative examples are described below. In order to avoid duplication with the descriptions in the examples, the comparative examples will focus on the differences between them and the examples.

[0097] In the comparative example, unlike the above embodiment, before processing, a jig was used to press the side wall portion 220', which was generally flat in cross-sectional view, inward in a substantially horizontal direction. This pressing formed a beading portion 221' that was recessed inward in a substantially horizontal direction at a predetermined location on the side wall portion 220' (see Figure 3).

[0098] Based on the above, a secondary battery equipped with an outer casing 200' having a beading portion 221' as in the comparative example was fabricated. In the secondary battery of the comparative example, flow of the constituent resin material occurred at a predetermined location of the gasket 400' that supports the sealing plate 320' of the sealing body 300'. As a result, it was found that insufficient compressive stress occurred in the gasket 400', making it difficult to ensure sealing between the outer casing 200' and the sealing body 300' by the gasket 400'.

[0099] Furthermore, the above-described embodiment of the present disclosure includes the following preferred embodiments. <1> The system comprises an outer casing having an opening at one end, a sealing body that seals the opening, and a gasket interposed between the outer casing and the sealing body. The exterior body comprises a side wall portion that forms the opening and a bottom portion continuous with the side wall portion, and the side wall portion comprises a beading portion that is continuous along the outer circumference and recessed toward the inside of the battery. The beading portion has an inwardly curved portion, and a gasket support wall portion that extends inward from the recess start point toward the inside of the battery and is capable of supporting the gasket. A secondary battery in which, in a cross-sectional view, the smallest R portion of the inner curved portion of the beading portion, where the radius of curvature is smallest, is located above the recess start point of the gasket support wall portion. <2> In a cross-sectional view, the gasket support wall portion of the beading section is inclined diagonally upward from the recess start point toward the minimum radius portion. <1> The secondary battery described above. <3> In a cross-sectional view, the minimum radius portion is partially embedded in the gasket. <1> or <2> The secondary battery described above. <4> In a cross-sectional view, the thickness dimension of a predetermined part of the gasket that contacts the minimum radius portion is smaller than the thickness dimension of other parts other than the predetermined part. <1> ~ <3> A secondary battery as described in any of the following. <5> In a cross-sectional view, the curvature angle of the minimum R portion is 90 degrees or less. <1> ~ <4> A secondary battery as described in any of the following. <6> The thickness of the side wall portion having the beading portion is 0.1 mm or more. <1> ~ <5> A secondary battery as described in any of the following. <7> The side wall portion of the outer casing has a crimping structure with respect to the sealing body. <1> ~ <6> A secondary battery as described in any of the following. <8> These are cylindrical, button-type, or coin-type rechargeable batteries. <1> ~ <7> A secondary battery as described in any of the following. [Industrial applicability]

[0100] The secondary battery described herein can be used in applications where the utilization of electrical energy is typically required. For example, the secondary battery described herein can be used in various fields where energy storage is anticipated. While these are merely examples, the batteries of this disclosure can be used in the electrical, information, and communication fields where electrical and electronic equipment is used (e.g., the electrical and electronic equipment field or mobile device field, including mobile phones, smartphones, laptops and digital cameras, activity trackers, ARM computers, electronic paper, wearable devices, and small electronic devices such as RFID tags, card-type electronic money, and smartwatches), household and small industrial applications (e.g., power tools, golf carts, household, caregiving, and industrial robots), large industrial applications (e.g., forklifts, elevators, and port cranes), transportation systems (e.g., hybrid vehicles, electric vehicles, buses, trains, electric assist bicycles, electric motorcycles, etc.), power grid applications (e.g., various power generation systems, road conditioners, smart grids, and general household energy storage systems), medical applications (medical equipment such as earphones and hearing aids), pharmaceutical applications (medication management systems, etc.), as well as IoT applications and space and deep-sea applications (e.g., space probes, submersible research vessels, etc.). [Explanation of Symbols]

[0101] 100 battery assembly 10A positive electrode 10B negative electrode 20 Electrolytes 50 Separators 200, 200' exterior 210 Bottom of the outer casing 220, 220' Side wall section of the exterior body 221, 221' Beading section 221a Inner recess 221b Inner recess 222 Minimum R part 223 Gasket support wall section 224, 224' Start point of the depression 225 Inner curved section 300, 300' sealing body 310, 310' Positive terminal 320, 320' sealing plate 330, 330' First metal member 331 Groove 340 Insulating material 350 Second metal component 351 Groove 352 Central area 353 Outer area 354 Opening 360 Conductive components 400, 400' gasket 500 storage units 1000 secondary battery M1-M5 jigs, metal components

Claims

1. The system comprises an outer casing having an opening at one end, a sealing body that seals the opening, and a gasket interposed between the outer casing and the sealing body. The exterior body comprises a side wall portion that forms the opening and a bottom portion continuous with the side wall portion, and the side wall portion comprises a beading portion that is continuous along the outer circumference and recessed toward the inside of the battery. The beading portion has an inwardly curved portion and a gasket support wall portion that extends inward from the recess start point toward the inside of the battery and is capable of supporting the gasket. A secondary battery in which, in a cross-sectional view, the smallest R portion of the inner curved portion of the beading portion, where the radius of curvature is smallest, is located above the recess start point of the gasket support wall portion.

2. The secondary battery according to claim 1, wherein, in a cross-sectional view, the gasket support wall portion of the beading portion is inclined diagonally upward from the recess start point toward the minimum radius portion.

3. The secondary battery according to claim 1, wherein, in a cross-sectional view, the minimum radius portion is partially embedded in the gasket.

4. The secondary battery according to claim 1, wherein, in a cross-sectional view, the thickness dimension of a predetermined portion of the gasket that contacts the minimum radius portion is smaller than the thickness dimension of other portions other than the predetermined portion.

5. The secondary battery according to claim 1, wherein, in a cross-sectional view, the curvature angle of the minimum R portion is 90 degrees or less.

6. The secondary battery according to claim 1, wherein the thickness of the side wall portion having the beading portion is 0.1 mm or more.

7. The secondary battery according to claim 1, wherein the side wall portion of the outer casing has a crimping structure with respect to the sealing body.

8. The secondary battery according to claim 1, which is cylindrical, button-shaped, or coin-shaped.

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