Battery

Abstract

To provide a battery with reduced shutoff variance as a safety valve.SOLUTION: In a battery having a safety valve, the safety valve includes a first metal member located on the outside, a second metal member located on the inside, and an insulating member located between the first metal member and the second metal member, the first metal member and the second metal member are connected to each other so as to straddle the insulating member, the second metal member has a groove in a cross-sectional view, the groove has at least two corners inside the groove in the cross-sectional view, and the shapes of the two corners are different from each other.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a battery, and more particularly to a battery having an electrode assembly made up of electrode constituent layers including a positive electrode, a negative electrode, and a separator. [Background technology]

[0002] Batteries can extract energy produced by chemical reactions or the like as electrical energy and are used in a variety of applications, including mobile devices such as mobile phones, smartphones, and laptops. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Patent Publication (WO) 2018 / 230148 [Patent Document 2] JP 2013-140672 A Summary of the Invention [Problem to be solved by the invention]

[0004] Safety is required for batteries. For example, a battery equipped with a safety valve capable of cutting off current in the event of an abnormality is considered. The inventors of the present application have earnestly examined whether there is still room for development of battery safety valves. As a result, they have found that there is still room for development of safety valves for cutting off current in the event of an abnormality in terms of cut-off variation.

[0005] The present invention has been made in view of the above problems. That is, a main object of the present invention is to provide a battery having cutoff characteristics with reduced cutoff variability as a safety valve. [Means for solving the problem]

[0006] The inventors of the present application attempted to solve the above problems by taking a new approach, rather than simply extending the conventional technology, and as a result, they came up with the invention of a battery that achieves the above-mentioned main object.

[0007] The battery according to the present invention comprises: The safety valve has a first metal member located on the outside, a second metal member located on the inside, and an insulating member located between the first metal member and the second metal member, the first metal member and the second metal member are connected to each other so as to straddle the insulating member, The second metal member has a groove in a cross-sectional view, and the groove has at least two corners therein in the cross-sectional view, and the shapes of the two corners are different from each other.

[0008] The battery according to the present invention comprises: The safety valve has a first metal member located on the outside, a second metal member located on the inside, and an insulating member located between the first metal member and the second metal member, the first metal member and the second metal member are connected to each other so as to straddle the insulating member, The second metal member has a groove in a cross-sectional view, and the groove has at least two corners inside the groove in the cross-sectional view, and the angle of one of the two corners is relatively larger than the angle of the other of the two corners in the cross-sectional view. Effect of the Invention

[0009] The battery according to the present invention can more appropriately interrupt current in the event of an abnormality. Specifically, the battery according to the present invention has two corners with different shapes and angles in cross section inside the groove of the metal member constituting the safety valve, which reduces current interruption variability in the action of the safety valve. [Brief description of the drawings]

[0010] [Figure 1]FIG. 1 is a schematic perspective view showing the appearance of a secondary battery according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing the internal configuration of a secondary battery according to one embodiment of the present invention. [Diagram 3] FIG. 3 is a schematic perspective view showing components and related members of a safety valve of a secondary battery according to one embodiment of the present invention in a developed state. [Figure 4] FIG. 4 is a schematic perspective view showing components of a safety valve of a secondary battery according to one embodiment of the present invention in a half-split and developed state. [Diagram 5] FIG. 5 is a schematic perspective view showing a half-cut safety valve of a secondary battery according to one embodiment of the present invention. [Figure 6] FIG. 6 is a schematic cross-sectional view of a safety valve of a secondary battery according to one embodiment of the present invention. [Figure 7] FIG. 7 is a schematic cross-sectional view of a stripper disk corresponding to the second metal member. [Figure 8] FIG. 8 is a schematic cross-sectional view of a groove provided in a stripper disk corresponding to the second metal member. [Figure 9] FIG. 9 is a schematic cross-sectional view of a stripper disk corresponding to the second metal member. [Figure 10] FIG. 10 is a schematic cross-sectional view of a groove provided in a stripper disk corresponding to the second metal member. [Figure 11] FIG. 11 is a schematic cross-sectional view of a stripper disk corresponding to the second metal member. [Figure 12] FIG. 12 is a schematic diagram showing an exemplary embodiment of a cleavage site of a stripper disk. [Figure 13] FIG. 13 is a schematic diagram showing a modified embodiment of the groove provided in the stripper disk corresponding to the second metal member. [Figure 14] Figure 14 is a diagram regarding the prerequisites for verification using Ansys 2022 R2. [Figure 15] 15(A) and (B) are diagrams regarding the prerequisites for verification using Ansys 2022 R2. [Figure 16] 16(A) to (D) are diagrams showing the prerequisites for verification using Ansys 2022 R2. [Figure 17] Figure 17 is a diagram regarding the prerequisites for verification using Ansys 2022 R2. [Figure 18] FIG. 18 is a schematic cross-sectional view showing the state of the safety valve before it is activated. [Figure 19] FIG. 19 is a schematic cross-sectional view showing a state of an activated safety valve. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] [Knowledge that formed the basis of this disclosure] In recent years, there has been a demand for improved battery reliability in line with the trend toward longer life and higher output.

[0012] The inventors of the present application have found that, although a certain battery safety valve can cut off current in the event of an abnormality and can accommodate higher output, etc., there is still room for development from another perspective. Specifically, the inventors of the present application have noticed that a safety valve assembled from a plurality of components is not necessarily satisfactory in terms of cutting off current in the event of an abnormality, and that there are cases in which current cutting off occurs undesirably when the battery internal pressure abnormally rises.

[0013] For example, in a battery equipped with a safety valve including a combination of a safety cover, a stripper disk, and an insulating member between them, a groove provided in the stripper disk can be used to cut off current in the event of an abnormality such as an increase in internal pressure. More specifically, the stripper disk is cleaved by the internal pressure of the battery in the event of an abnormality, starting from a corner of the groove, to cut off current. Since the cleavage occurs based on the groove, the groove in the stripper disk can be called a "cleavage groove." In the course of verifying current interruption, the inventor of the present application has noticed the need to improve the reliability of the cleavage of the stripper disk. Specifically, the inventor of the present application has found that when the stripper disk breaks, the "interruption variation" may become large.

[0014] In particular, in cases where current conduction was observed even after the occurrence of a breaking sound that could correspond to the breakage of the stripper disk, there was a tendency for the current interruption location of the cleavage groove after the breakage to vary, or for the breaking pressure to vary (e.g., the breaking pressure to vary as a higher breaking pressure). In other words, it was found that the cases in which current conduction was observed after the breakage sound had a greater breaking variation in terms of the breaking location and / or the breaking pressure than the desired cases in which no current conduction was observed after the breakage sound.

[0015] The inventors of the present application attempted to solve such problems by taking a new approach rather than simply extending the conventional technology, and as a result, they invented a battery that reduces or avoids shutoff variability in the event of an abnormality such as an increase in the battery's internal pressure, thereby improving the reliability of the safety valve.

[0016] The following describes the embodiments of the present invention in detail. Please note that the applicant provides the following description and examples to allow those skilled in the art to fully understand the present invention, and does not intend to limit the subject matter described in the claims. In other words, the present invention is not particularly limited to the preferred embodiments described below, and can be modified and implemented as appropriate within the scope of its purpose. In addition, in consideration of the explanation or ease of understanding of the main points, the present invention may be shown in separate embodiments and examples for convenience, but partial replacement and / or combination of the configurations shown in different embodiments is possible. In the description of such embodiments, the description of matters common to the above may be omitted, and only the differences may be described. In particular, the same action and effect due to the same configuration may not be mentioned in each embodiment.

[0017] In the description of the present specification, references to directions or orientations are merely for convenience of description and are not intended to limit the scope of the present invention unless otherwise expressly described. For example, relative terms such as "outside (or outer, external or outer circumference)", "inside (or inner, internal or inner circumference)", "bottom" and their derivatives should be understood to refer to the direction as described or illustrated. In other words, unless otherwise expressly described, the invention does not need to be limited to a specific direction, orientation, form, etc. Similarly, terms such as "provided", "disposed", "connected" and "bonded" and their derivatives are also applicable, and unless otherwise expressly described, they may be in a form in which other elements such as intervening objects are present, not limited to a direct form. In addition, various numerical ranges referred to in this specification are intended to include the lower and upper limit values ​​themselves, unless otherwise specified. In other words, for example, a numerical range such as 1 to 10 can be interpreted as including the lower limit "1" and the upper limit "10".

[0018] [Basic battery configuration] The term "battery" in this specification includes not only so-called "secondary batteries" but also "primary batteries" that can only be discharged. In other words, the term "battery" in this specification may be a "secondary battery" that can be repeatedly charged and discharged, or a "primary battery" that can only be discharged. Note that the term "secondary battery" is not overly limited to its name, and may also include, for example, an "electricity storage device."

[0019] For convenience of explanation, the battery according to the present invention will be explained below mainly taking a secondary battery as an example.

[0020] The secondary battery according to the present invention has an electrode assembly composed of electrode constituent layers including a positive electrode, a negative electrode, and a separator. The secondary battery according to the present invention may have a wound structure in which such electrode constituent layers are wound into a roll (hereinafter, also referred to as a "wound electrode body" or a "wound structure"). FIG. 1 shows an exemplary embodiment of the external appearance of a secondary battery 1000, and FIG. 2 shows an exemplary embodiment of its internal structure. As shown in the figure, an electrode assembly 10 is accommodated inside a battery can 50. In the exemplary embodiment shown in FIG. 2, the electrode assembly 10 has a configuration in which a positive electrode 11, a negative electrode 12, and a separator 13 arranged between the positive electrode and the negative electrode are wound. In the secondary battery 1000, such an electrode assembly 10 is enclosed in a battery can 50 together with an electrolyte (e.g., a non-aqueous electrolyte).

[0021] The positive electrode is composed of at least a positive electrode material layer and a positive electrode current collector. In the positive electrode, the positive electrode material layer is provided on at least one side of the positive electrode current collector. The positive electrode material layer contains a positive electrode active material as an electrode active material. For example, each of the multiple positive electrodes in the electrode assembly may have a positive electrode material layer provided on both sides of the positive electrode current collector, or may have a positive electrode material layer provided only on one side of the positive electrode current collector.

[0022] The negative electrode is composed of at least a negative electrode material layer and a negative electrode current collector. In the negative electrode, the negative electrode material layer is provided on at least one side of the negative electrode current collector. The negative electrode material layer contains a negative electrode active material as an electrode active material. For example, each of the multiple negative electrodes in the electrode assembly may have a negative electrode material layer provided on both sides of the negative electrode current collector, or may have a negative electrode material layer provided only on one side of the negative electrode current collector.

[0023] The electrode active materials contained in the positive electrode and the negative electrode, that is, the positive electrode active material and the negative electrode active material, respectively, are materials directly involved in the transfer of electrons in the 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 to 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 such ions move between the positive electrode and the negative electrode to transfer electrons and charge and discharge. The positive electrode material layer and the negative electrode material layer may be layers capable of absorbing and releasing lithium ions in particular. In other words, the secondary battery according to the present invention may be a non-aqueous electrolyte secondary battery in which lithium ions move between the positive electrode and the negative electrode via the non-aqueous electrolyte to charge and discharge the battery. When lithium ions are involved in charging and discharging, the secondary battery according to the present invention corresponds to a so-called "lithium ion battery", and has electrodes capable of absorbing and releasing lithium ions as the positive electrode and the negative electrode, and preferably has a layer capable of absorbing and releasing the lithium ions.

[0024] In view of the lithium ion battery, the positive electrode active material may be a material that contributes to the absorption and release of lithium ions. In other words, the positive electrode layer may contain any one or more of positive electrode materials that can absorb and release 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 thereof include lithium-containing composite oxides and lithium-containing phosphate compounds. This is because high energy density is easily obtained.

[0025] The lithium-containing composite oxide is 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 and a spinel type, for example. The lithium-containing phosphate compound is 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), and iron (Fe), etc. This is because a high voltage is easily obtained.

[0026] 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 and 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 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 to d satisfy 0.8≦a≦1.2, 0.005≦b≦0.5, -0.1≦c≦0.2, and 0≦d≦0.1. However, the composition of lithium varies depending on the charge / discharge state, and a is the value in a fully discharged state.) Li a Co (1-b) M13 b O (2-c) F d (3) (M13 is at least one of 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 to d satisfy 0.8≦a≦1.2, 0≦b<0.5, -0.1≦c≦0.2, and 0≦d≦0.1. However, the composition of lithium varies depending on the charge / discharge state, and a is the value in a fully discharged state.) Specific examples of lithium-containing composite oxides having a layered rock salt type crystal structure include LiNiO2, LiCoO2, and LiCoO 0.98 Al 0.01 Mg 0.01 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.8 Co 0.15 Al 0.05 O2, LiNi 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 (M 0.65 Ni0.22 Co 0.13 )O2, etc. When the lithium-containing composite oxide having a layered rock-salt crystal structure contains nickel, cobalt, manganese and aluminum as constituent elements, the atomic ratio of nickel is preferably 50 atomic % or more, because a high energy density is easily obtained.

[0027] The 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 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 to d satisfy 0.9≦a≦1.1, 0≦b≦0.6, 3.7≦c≦4.1, and 0≦d≦0.1. However, the composition of lithium varies depending on the charge / discharge state, and a is the value in a fully discharged state.) A specific example of the lithium-containing composite oxide having a spinel type crystal structure may be LiMn2O4.

[0028] The lithium-containing phosphate compound having an olivine type crystal structure is, for example, a compound represented by the following formula (5). Li a M15PO4···(5) (M15 is at least one of 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 in a fully discharged state.) Specific examples of lithium-containing phosphate compounds having an olivine crystal structure include LiFePO4, LiMnPO4, and LiFe 0.5 Mn 0.5 PO4 and LiFe 0.3 Mn 0.7 It may be PO4, etc.

[0029] The lithium-containing composite oxide may be a compound represented by the following formula (6). (Li2MnO3) x (LiMnO2) 1-x (6) (x satisfies 0≦x≦1. However, the lithium composition varies depending on the charge / discharge state, and x is the value in a fully discharged state.)

[0030] In addition, the positive electrode material may be, for example, one or more of oxides, disulfides, chalcogenides, conductive polymers, etc. The oxides may be, for example, titanium oxide, vanadium oxide, manganese dioxide, etc. The disulfides may be, for example, titanium disulfide, molybdenum sulfide, etc. The chalcogenides may be, for example, niobium selenide, etc. The conductive polymers may be, for example, sulfur, polyaniline, polythiophene, etc. However, the positive electrode material is not particularly limited and may be other materials than those mentioned above.

[0031] The positive electrode layer may contain a binder. In addition, the positive electrode layer may contain a positive electrode conductive agent to facilitate the transfer of electrons that promote the battery reaction. The binder of the positive electrode may contain, for example, one or more of synthetic rubber and polymer compounds. Examples of synthetic rubber include styrene butadiene rubber, fluorine-based rubber, and ethylene propylene diene. Examples of polymer compounds include polyvinylidene fluoride and polyimide. The positive electrode conductive agent may contain, for example, one or more of carbon materials. Examples of the carbon materials may include graphite, carbon black, acetylene black, and ketjen black. However, the positive electrode conductive agent may be a metal material, a conductive polymer, or the like, as long as it is a material that has conductivity.

[0032] Similarly, the negative electrode active material of the negative electrode layer may be a material that contributes to the absorption and desorption of lithium ions. That is, the negative electrode layer may contain any one or more types of negative electrode materials that can absorb and desorb lithium. From this perspective, the negative electrode active material may be, for example, various carbon materials, metal materials, and / or other materials.

[0033] When a carbon material is used as the negative electrode active material, the change in the crystal structure during lithium absorption and desorption is very small, so that a high energy density can be stably obtained. In addition, the carbon material also functions as a negative electrode conductive agent, so that the conductivity of the negative electrode layer can be easily improved.

[0034] Specific examples of carbon materials include graphitizable carbon, non-graphitizable carbon, and / or graphite. More specifically, the carbon material may be, for example, pyrolytic carbons, cokes, glassy carbon fiber, organic polymer compound sintered bodies, activated carbon, and carbon blacks. The cokes may include pitch coke, needle coke, and petroleum coke. The organic polymer compound sintered bodies are, for example, substances in which polymer compounds such as phenol resins and furan resins are sintered (carbonized) at an appropriate temperature. In addition, the carbon material may be low-crystalline carbon that has been heat-treated at a temperature of about 1000° C. or less, or may be amorphous carbon. The shape of the carbon material is not particularly limited, and may be at least one of fibrous, spherical, granular, and scaly shapes.

[0035] The "metal-based material" used as the negative electrode active material is a general term for a material containing one or more of metal elements and metalloid elements as constituent elements. When a carbon material is used as the negative electrode active material, a high energy density is easily obtained. The metal-based material may be a single substance, an alloy, a compound, or two or more of them, or may be a material containing at least one or more phases of them. However, the alloy may include a material containing one or more metal elements and one or more metalloid elements in addition to a material consisting of two or more metal elements. The alloy may also contain a nonmetallic element. The structure of this metal-based material may be, for example, a solid solution, a eutectic (eutectic mixture), an intermetallic compound, or a coexistence of two or more of them. Such a metal element and metalloid element may be, for example, one or more of metal elements and metalloid elements that can form an alloy with lithium. Specifically, the metal element and the metalloid element 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, hafnium (Hf), zirconium, yttrium (Y), palladium (Pd) and / or platinum (Pt). In a preferred embodiment, the metal element or the metalloid element is silicon and tin. This is because they have excellent ability to absorb and release lithium, and therefore it is easy to obtain a higher energy density. The material containing silicon as a constituent element may be silicon alone, a silicon alloy, a silicon compound, or two or more types selected from them, or may be a material that contains one or more phases of them at least in a part. Similarly, a material containing tin as a constituent element may be a simple substance of tin, a tin alloy, a tin compound, or two or more of these, or may be a material that contains at least one or more of these phases in part. The term "simple substance" as used herein refers to a simple substance in the general sense, and may contain a trace amount of impurities.That is, the purity of a single substance is not necessarily limited to 100%. Silicon alloys 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. Silicon compounds may contain, for example, any one or more of carbon and oxygen as constituent elements other than silicon. Note that silicon compounds may also contain any one or more of the series of elements described for silicon alloys as constituent elements other than silicon. Specific examples of silicon alloys and silicon compounds 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 the v in it may be 0.2 < v < 1.4. Tin alloys 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. Tin compounds may contain, for example, any one or more of carbon and oxygen as constituent elements other than tin. Note that tin compounds may also contain any one or more of the series of elements described for tin alloys as constituent elements other than tin. Specific examples of tin alloys and tin compounds 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 and excellent cycle characteristics, etc. are easily obtained. 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 a high energy density is easily obtained. 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 of tin and crystallization of tin, etc. are easily suppressed. 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, in addition to tin, cobalt, and carbon, any one or more of silicon, iron, nickel, chromium, indium, niobium, germanium, titanium, molybdenum, aluminum, phosphorus, gallium, and bismuth as constituent elements. 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.

[0036] In addition, the negative electrode material may be, for example, any one or more of metal oxides and polymer compounds. The metal oxide may be, for example, iron oxide, ruthenium oxide, and molybdenum oxide. The polymer compound may be, for example, polyacetylene, polyaniline, and polypyrrole.

[0037] The negative electrode material layer may contain a binder. Furthermore, the negative electrode material layer may contain a negative electrode conductive agent to facilitate the transfer of electrons that promote the battery reaction. The binder that may be contained in the negative electrode material layer is not particularly limited, but at least one selected from the group consisting of styrene butadiene rubber, polyacrylic acid, polyvinylidene fluoride, polyimide resins, and polyamideimide resins can be mentioned. The negative electrode conductive agent that may be contained in the negative electrode material layer is not particularly limited, but at least one selected from 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 contain a component resulting from a thickener component (e.g., carboxymethyl cellulose) used during battery production.

[0038] The positive electrode current collector and the negative electrode current collector used for the positive electrode and the negative electrode are members that contribute to collecting and supplying electrons generated in the electrode active material due to the battery reaction. Such an electrode current collector may be a sheet-shaped metal member. The electrode current collector may be a single layer or a multilayer. Furthermore, the electrode current collector may have a porous or perforated form. For example, the current collector may be a metal foil, a punched metal, a net, an expanded metal, or the like. The positive electrode current collector used for the positive electrode may be, for example, a metal foil containing at least one selected from the group consisting of aluminum, nickel, stainless steel, and the like. On the other hand, the negative electrode current collector used for the negative electrode may be, for example, a metal foil containing at least one selected from the group consisting of copper, aluminum, nickel, stainless steel, and the like.

[0039] The separator used for the positive and negative electrodes is a member provided from the viewpoint of preventing short circuit caused by contact between the positive and negative electrodes and retaining the electrolyte. In other words, the separator is a member that separates the positive and negative electrodes and allows ions (e.g., lithium ions) to pass through while preventing short circuit of current caused by contact between the two electrodes. For example, the separator may be a porous or microporous insulating member, and may have a membrane form due to its small thickness.

[0040] The separator may be, for example, one or more of a porous film such as a synthetic resin and / or a ceramic, or may be a laminated film of two or more of the porous films. Examples of the synthetic resin used for the separator include polytetrafluoroethylene, polypropylene, and polyethylene. For example, the separator may include a porous film (substrate layer) and a polymer compound layer provided on one or both sides of the substrate layer. Since the adhesion of the separator to the positive electrode and the adhesion of the separator to the negative electrode can be improved, the distortion of the wound electrode body can be easily suppressed. The polymer compound layer may include, for example, one or more of a polymer compound such as polyvinylidene fluoride. The polymer compound layer has excellent physical strength and is easily electrochemically stable. The polymer compound layer may include, for example, one or more of insulating particles such as inorganic particles. The type of inorganic particles may be, for example, aluminum oxide and / or aluminum nitride. In the present invention, the separator should not be limited to a particular name, and may be a solid electrolyte, a gel electrolyte, and / or insulating inorganic particles having similar functions.

[0041] In the secondary battery of the present invention, an electrode assembly consisting of electrode constituent layers including a positive electrode, a negative electrode, and a separator may be enclosed in an exterior body together with an electrolyte. The electrolyte may be a so-called "non-aqueous" electrolyte.

[0042] The electrolyte may typically be an electrolytic solution. The electrolytic solution includes a solvent and an electrolyte salt. The electrolytic solution may further include any one or more of other materials such as additives. In a preferred embodiment, the separator is impregnated with the electrolytic solution, and the positive electrode and / or the negative electrode may also be impregnated with the electrolytic solution.

[0043] The solvent may include any one or more of non-aqueous solvents such as organic solvents. An electrolyte solution including a non-aqueous solvent may be a so-called non-aqueous electrolyte solution. The non-aqueous solvent may be, for example, a cyclic carbonate ester, a chain carbonate ester, a lactone, a chain carboxylate ester, and / or a nitrile (e.g., mononitrile). This is because it is easy to obtain better battery capacity, cycle characteristics, and / or storage characteristics. The cyclic carbonate ester may be, for example, ethylene carbonate, propylene carbonate, and / or butylene carbonate. The chain carbonate ester may be, for example, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and / or methyl propyl carbonate. The lactone may be, for example, γ-butyrolactone and / or γ-valerolactone. The chain carboxylate ester may be, for example, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, methyl isobutyrate, methyl trimethyl acetate, and / or ethyl trimethyl 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. Among them, the non-aqueous solvent preferably contains one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. This is because it is easy to bring about a higher battery capacity, better cycle characteristics, and / or better storage characteristics. Furthermore, the non-aqueous solvent may be, for example, an unsaturated cyclic carbonate, a halogenated carbonate, a sulfonate, an acid anhydride, a dicyano compound (a dinitrile compound), a diisocyanate compound, a phosphate ester, and / or a chain compound having a carbon-carbon triple bond.This is because the chemical stability of the electrolyte solution is easily improved. The term "unsaturated cyclic carbonate" as used herein refers to a cyclic carbonate having one or more unsaturated bonds (carbon-carbon double bonds or carbon-carbon triple bonds). Examples of the unsaturated cyclic carbonate include vinylene carbonate, vinylethylene carbonate, and / or methyleneethylene carbonate. The term "halogenated carbonate" refers to a cyclic or chain-like carbonate containing one or more halogen elements as constituent elements. When the halogenated carbonate contains two or more halogens as constituent elements, the type of the two or more halogens may be only one type or may be two or more types. Examples of the cyclic halogenated carbonate include 4-fluoro-1,3-dioxolane-2-one and / or 4,5-difluoro-1,3-dioxolane-2-one. Examples of the chain-like halogenated carbonate include fluoromethyl methyl carbonate, bis(fluoromethyl) carbonate, and / or difluoromethyl methyl carbonate. The sulfonate ester may be, for example, a monosulfonate ester and / or a disulfonate ester. The monosulfonate ester may be, for example, a cyclic monosulfonate ester or a chain monosulfonate ester. The cyclic monosulfonate ester may be, for example, a sultone such as 1,3-propane sultone and / or 1,3-propene sultone. The chain monosulfonate ester is, for example, a compound in which a cyclic monosulfonate ester is cut in the middle. The disulfonate ester may be, for example, a cyclic disulfonate ester or a chain disulfonate ester. The acid anhydride may be, for example, a carboxylic acid anhydride, a disulfonic acid anhydride and / or a carboxylic acid sulfonic acid anhydride. The carboxylic acid anhydride may be, for example, succinic acid anhydride, glutaric acid anhydride and / or maleic acid anhydride. The disulfonic acid anhydride may be, for example, ethane disulfonic acid anhydride and / or propane disulfonic acid anhydride. The carboxylic acid sulfonic acid anhydride may be, for example, sulfobenzoic anhydride, sulfopropionic anhydride, and / or sulfobutyric anhydride, etc. The dinitrile compound may be, for example, NC-R1-CN (R1 is either an alkylene group or an arylene group).) is a compound represented by the formula: The dinitrile compound may be, for example, succinonitrile (NC-C2H4-CN), glutaronitrile (NC-C3H6-CN), adiponitrile (NC-C4H8-CN), phthalonitrile (NC-C6H4-CN), etc. The diisocyanate compound is, for example, a compound represented by the formula: OCN-R2-NCO (R2 is either an alkylene group or an arylene group). The diisocyanate compound is, for example, hexamethylene diisocyanate (OCN-C6H. 12 The phosphate ester may be, for example, trimethyl phosphate and triethyl phosphate. The chain compound having a carbon-carbon triple bond is a chain compound having one or more carbon-carbon triple bonds (-C≡C-). The chain compound having a carbon-carbon triple bond may be, for example, propargyl methyl carbonate (CH≡C-CH2-OC(=O)-O-CH3) and propargyl methylsulfonate (CH≡C-CH2-OS(=O)2-CH3).

[0044] The electrolyte salt contained in the electrolytic solution may include, for example, one or more of salts such as lithium salt. The electrolyte salt may include, for example, a salt other than lithium salt. Such salt other than lithium may be, for example, a salt of a light metal other than lithium. Examples of the lithium salt include lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (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, any one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, and lithium hexafluoroarsenate may be used.

[0045] The battery can used in the secondary battery corresponds to a member that, as a battery exterior, encloses an electrode assembly in which electrode constituent layers including a positive electrode, a negative electrode, and a separator are laminated. The battery can may have, for example, a hollow structure with one end closed and the other end open (open as an open end). The battery can may be a metal can containing, but is not particularly limited to, any one or more of metal materials such as iron, aluminum, stainless steel, and alloys thereof. The surface of the battery can may be plated with, for example, any one or more of metal materials such as nickel. The open end of the battery can may be provided with a safety valve. Although this is merely an example, the open end of the battery can may be provided with a safety valve via a gasket together with a thermosensitive resistor or the like (that is, the safety valve of the battery may be provided together with, for example, a crimping mechanism).

[0046] [Characteristics of the Battery of the Present Invention] The battery of the present invention has features related to its safety mechanism, in particular, a safety valve provided in the battery can (particularly at the open end thereof).

[0047] The safety valve provided in the battery of the present invention comprises at least a first metal member, a second metal member, and an insulating member located between them. The first metal member is located relatively outside in the battery axial direction, while the second metal member is located relatively inside in the battery axial direction, and they are electrically connected to each other. Preferably, the first metal member and the second metal member are connected to each other in a form that straddles the insulating member. The first metal member and the second metal member may each be a disk-shaped or plate-shaped member (that is, may have a form that extends on the same plane as a whole). As will be mentioned later, the insulating member preferably has an opening or a hollow portion in its inner or central region, and may be plate-shaped (e.g., flat) or flat as a whole. In the present invention, such first metal member, second metal member, and insulating member are preferably arranged so as to be directly stacked on each other, and a thin safety valve is formed. Also,

[0048] In the safety valve according to the present invention, a groove is provided in the second metal member. The groove in the second metal member has a corner having a specific shape inside. Specifically, the groove in the second metal member has at least two corners inside the groove in a cross-sectional view, and the shapes of the two corners are different from each other. It can also be said that, in a cross-sectional view of the second metal member, two corners that are different from each other are provided inside the groove as a cross-sectional view contour.

[0049] As described later, the groove of the second metal member contributes to the rupture of the second metal member when the battery internal pressure is applied in an abnormal state, and therefore can be regarded as a "groove for rupture". Due to the above-mentioned specific form of such a groove for rupture, a safety valve with reduced interruption variability can be obtained. In other words, when using the groove for rupture of the second metal member to interrupt current in an abnormal state such as an increase in internal pressure, the rupture location variability of the groove for rupture of the second metal member can be further reduced and / or the interruption pressure variability can be further reduced due to the "groove for rupture having at least two corners inside in a cross-sectional view, and the shapes of the two corners are different from each other". As a result, a battery with improved reliability of the safety valve is obtained. For example, in a battery with less such variability, the predictability of an abnormal increase in internal pressure is improved, and a battery with a higher degree of design freedom can be realized. Alternatively, a battery in which the conduction of current is desired to be avoided thereafter can be easily realized so as to more appropriately respond to the rupture sound of the second metal member.

[0050] The battery of the present invention will be described in detail below with reference to the drawings as appropriate. The safety valve of the battery of the present invention is configured to have at least a first metal member, a second metal member, and an insulating member located between them. As a specific example embodiment, the first metal member corresponds to a safety cover, and the second metal member corresponds to a stripper disk.

[0051] 1 and 2 are schematic diagrams showing the appearance and cross-sectional view of a secondary battery according to an embodiment of the present invention. As shown in the figures, the secondary battery 1000 of the present invention may be a cylindrical secondary battery (e.g., a cylindrical nonaqueous secondary battery). In other words, the secondary battery of the present invention may have a cylindrical case, i.e., a cylindrical battery can 50. The safety valve 100 may be provided at the cylindrical end of the secondary battery 1000 (particularly, at the open end side of the battery can). FIG. 3 shows the safety valve 100 together with its related members (or peripheral members) in an expanded state, and FIG. 4 shows each component of the safety valve 100 as a half-split perspective view.

[0052] As shown in Fig. 3 and Fig. 4, the safety valve 100 has a configuration in which a safety cover 110 provided as a first metal member, an insulating member 120, and a stripper disk 130 provided as a second metal member are combined with each other in that order along a battery axis P. When viewed along the axial direction of the cylindrical shape of the battery, the safety cover 110 of the first metal member is positioned relatively outside the battery (i.e., the side farther from an electrode assembly such as a wound structure), while the stripper disk 130 of the second metal member is positioned relatively inside the battery (i.e., the side closer to an electrode assembly such as a wound structure), and an insulating member 120 is interposed between the safety cover 110 and the stripper disk 130. In this specification, the "battery axis" refers to an axis P that extends in a direction perpendicular to an end face of the battery can (particularly an imaginary planar end face) so as to pass through the center of the battery can corresponding to the battery exterior body (see Figs. 1 and 2). For example, the battery axis can be said to refer to an axis that passes through the center of the exterior body 50 and extends in a direction perpendicular to the extension direction of the safety valve 100. Therefore, expressions such as "battery axis direction" described above or below refer to the direction along the battery axis.

[0053] Each member constituting the safety valve 100 will be described in detail. The safety valve 100 serves as a battery terminal (i.e., one of the positive and negative terminals as the external terminal of the battery) and has a mechanism that can be displaced in response to excessive internal battery pressure as a battery safety mechanism. Thus, the safety valve 100 has a safety cover 110 and a stripper disk 130 that can be displaced in response to excessive internal battery pressure, and at least an insulating member 120 between them as a component. Such a safety valve 100 may be provided at one end of the battery can, and is provided at the opening end 51 in the battery can 50 of Figs. 1 and 2. In addition, in the safety valve 100, a top cover 150 may be provided on the outside in the battery axis direction of the safety cover 110 provided as the first metal member (see Figs. 3 and 4).

[0054] The safety cover 110 provided as the first metal member corresponds mainly to a displaceable member that can close the open end 51 of the battery can 50 and can be deformed and / or opened in response to an increase in the internal pressure of the battery can. The internal pressure of the battery can may increase due to a side reaction such as a decomposition reaction of the electrolyte. That is, when a side reaction such as a decomposition reaction of the electrolyte occurs, gas such as carbon dioxide is generated inside the battery can, and the internal pressure of the battery can may increase undesirably in response to an increase in the amount of gas generated.

[0055] The safety cover 110 may be a metal member. For example, the safety cover 110 may include one or more of metal materials such as iron (Fe), aluminum (e.g., aluminum metal or aluminum alloy such as A1050, A3203, and / or A5052), titanium (Ti), platinum (Pt), and gold (Au). In other words, the safety cover 110 may be a member made of such a conductive material. The planar shape of the safety cover 110, particularly the outer contour shape in plan view (hereinafter also referred to as "outer contour shape in plan view") is not particularly limited, and may be, for example, a circle, a polygon, or other shape. Examples of a circle include a perfect circle (correct circle), an ellipse, and an approximate circle. Examples of an approximate circle include a shape in which a perfect circle is partially or entirely distorted. Examples of a polygon include a triangle, a rectangle, a pentagon, and a hexagon. Other shapes include, for example, shapes other than a circle whose outline is formed only by curves, a shape in which two or more types of polygons are combined, and a shape in which one or more types of circles and one or more types of polygons are combined. The definition of "circle" will be the same hereinafter. In the illustrated embodiment, the outer outline shape of the safety cover 110 in a plan view is a circle.

[0056] The safety cover 110 may be, for example, flat as a whole. In other words, the safety cover 110 may have a shape that extends on the same plane as a whole. By way of example only, the safety cover 110 may have a substantially constant thickness except for grooves (for example, displacement grooves that contribute to the displacement, deformation, or breakage of the safety cover) provided therein. Such a safety cover 110 that has a shape that extends on the same plane as a whole contributes to making the battery safety valve thinner.

[0057] The insulating member 120 corresponds to a member that is interposed between the safety cover 110 and the stripper disk 130 and at least enables the safety cover 110 and the stripper disk 130 to be connected to each other. The insulating member 120 may have an annular shape as a whole. That is, the insulating member 120 may have a ring shape or a ring shape in a plan view. Due to such a ring shape or ring shape, the insulating member 120 has an inner region that forms a hollow portion or an opening region 120C (i.e., an "opening" described later). The outer contour shape of such an insulating member 120 in a plan view is not particularly limited, but may be the same as the outer contour shape of the safety cover 110 in a plan view, and may be, for example, a circular shape. The insulating member 120 may have a ring shape or a ring shape as a whole member, or may have a form in which the ring shape or ring shape is locally divided (see FIG. 3). The insulating member 120 may have, for example, a flat plate shape as a whole. That is, the insulating member 120 may have a shape that extends on the same plane as a whole. The insulating member 120 having such a shape that extends on the same plane contributes to making the battery safety valve thinner. By way of example only, the insulating member 120 may have a substantially constant thickness between the safety cover 110 and the stripper disk 130. Preferably, the insulating member 120 may be interposed between the safety cover 110 and the stripper disk 130 such that the opening region 120C of the insulating member 120 is positioned in a region that includes the battery axis.

[0058] Since the insulating member 120 has insulating properties, electrical conduction through the insulating member 120 is preferably prevented. In this specification, "insulating" may have insulating properties that a general insulator has, and therefore may have an electrical resistivity that a general insulator has, and while this is merely an example, it may be at least 1.0×10 5 Ω·m or more, preferably 1.0×10 6 Ω·m or more, preferably 1.0×10 7 It may have a resistivity of Ω·m or more (at room temperature of 20°C).

[0059] In a preferred embodiment, the insulating member 120 interposed between the safety cover 110 and the stripper disk 130 may be one that contributes to insulation and may not necessarily be bonded to them. On the other hand, for example, when bonded, the insulating member 120 may be interposed between the safety cover 110 and the stripper disk 130 as an adhesive layer. The insulating member 120 may be interposed between the safety cover 110 and the stripper disk 130 so that the opening region 120C of the insulating member 120 is positioned in a region including the battery shaft.

[0060] The insulating member 120 is preferably made of a resin material. That is, the main component of the insulating member may be a resin material, or the insulating member may be made to contain at least a resin in its material. When made of a resin material in this way, the insulating member 120 contributes more favorably to the adhesion between the safety cover 110 and the stripper disk 130 while ensuring insulation, and thus the insulating member 120 contributes to realizing a thinner safety valve. For example, the insulating member 120 may be made of a thermosetting resin, a thermoplastic resin, and / or a UV-curable resin. When the connectivity aspect is particularly important, the insulating member 120 may be a member containing a resin adhesive that exhibits insulation. Examples of such resin adhesives include acrylic resin adhesives such as acrylic acid ester copolymers, silicone resin adhesives such as silicone rubber, urethane resin adhesives such as urethane resin, α-olefin resin adhesives, ether resin adhesives, ethylene-vinyl acetate resin adhesives, epoxy resin adhesives, vinyl chloride resin adhesives, chloroprene rubber resin adhesives, cyanoacrylate resin adhesives, aqueous polymer-isocyanate resin adhesives, styrene-butadiene rubber resin adhesives, nitrile rubber resin adhesives, nitrocellulose resin adhesives, and reactive hot melt resin adhesives. Examples of the adhesive include a phenol resin-based resin adhesive, a silicone resin-based resin adhesive, a polyamide resin-based resin adhesive, a polyimide resin-based resin adhesive, a polyurethane resin-based resin adhesive, a polyolefin resin-based resin adhesive, a polyvinyl acetate resin-based resin adhesive, a polystyrene resin solvent-based resin adhesive, a polyvinyl alcohol-based resin adhesive, a polyvinylpyrrolidone resin-based resin adhesive, a polyvinyl butyral resin-based resin adhesive, a polybenzimidazole-based resin adhesive, a polymethacrylate resin-based resin adhesive, a melamine resin-based resin adhesive, a urea resin-based resin adhesive, and / or a resorcinol-based resin adhesive.

[0061] The insulating member 120 has an opening 120C at a position corresponding to the central region 110C of the safety cover 110 (see Figs. 3 and 4). The opening 120C corresponds to an inner opening region or a hollow region of the insulating member that provides the insulating member 120 with an annular shape (annular or ring shape). The opening 120C of the insulating member 120 may be provided in a region including the battery axis. The opening shape of the opening 120C of the insulating member 120 (particularly the planar opening shape in a planar view) is not particularly limited, and may be the same as the outer contour shape of the safety cover 110 in a planar view, for example. In the illustrated exemplary embodiment, the opening shape of the opening 120C of the insulating member 120 is circular.

[0062] The stripper disk 130 provided as the second metal member is positioned relatively closer to the battery inside the safety cover 110 via the insulating member 120, and corresponds to a member that contributes to current interruption in the event of an abnormality and / or the passage or release of gas, for example, inside the battery can.

[0063] The stripper disk 130 may be a metal member. For example, the stripper disk 130 may include one or more of metal materials such as iron (Fe), aluminum (e.g., aluminum metal or aluminum alloy such as A1050, A3203, and / or A5052), titanium (Ti), platinum (Pt), and gold (Au). In other words, the stripper disk 130 may be a member made of such a conductive material. The material of the stripper disk 130 may be the same as the material of the safety cover 110, or may be different from the material of the safety cover 110. The outer contour shape of the stripper disk 130 in plan view is not particularly limited, but is, for example, the same as the outer contour shape of the safety cover 110 in plan view. In the illustrated exemplary embodiment, the outer contour shape of the stripper disk 130 in plan view is circular.

[0064] The stripper disk 130 may be, for example, flat as a whole. That is, the stripper disk 130 may have a shape that extends on the same plane. Such a stripper disk that extends on the same plane as a whole contributes to making the battery safety valve thinner. For example, the stripper disk 130 may have a substantially constant thickness as a whole except for a central region. The central region 130C of the stripper disk 130 may be raised relatively to the other regions (preferably raised outward along the battery axis) to contribute to connection with the safety cover 110. In other words, the stripper disk 130 may have a plate-like shape as a whole, but at least the central portion of the region including the battery axis may be relatively protruding.

[0065] The stripper disk 130 may have a plurality of openings 130K. The plurality of openings 130K mainly correspond to vents that allow gas inside the battery can to pass through or be released. For example, the plurality of openings 130K may be provided in a region that is closer to the outer periphery than the central region 130C.

[0066] In the safety valve, the safety cover 110 and the stripper disk 130 are integrated as a whole with the insulating member 120 interposed therebetween, but the safety cover 110 and the stripper disk 130 may be electrically connected to each other in their central regions. For example, the safety cover 110 may be directly connected to the central region 130C of the stripper disk 130 so as to straddle the insulating member 120. More specifically, as shown in Fig. 3, Fig. 5, Fig. 6, etc., the central region 110C of the safety cover 110 and the central region 130C of the stripper disk 130 may be directly connected to each other through the opening 120C of the insulating member 120.

[0067] As described above, the safety valve may further include a top cover 150. That is, the top cover 150 may be provided relatively outward in the battery axial direction from the safety cover 110 provided as the first metal member. In the safety valve, the top cover 150 is preferably electrically connected to the safety cover 110. The top cover corresponds to a battery cover provided to cover the open end of the battery can together with other components of the safety valve. In other words, the safety cover 110 is connected to the top cover 150 that constitutes the external terminal of the battery. As shown in FIG. 3 and FIG. 4, the top cover 150 has a protrusion 150A that protrudes outward in the battery axial direction. The protrusion 150A is provided particularly in the central region of the top cover. The convex portion 150A of the top cover 150 has a shape that protrudes outward from the battery, and the top cover 150 includes at least one bent portion 150C extending from the flat portion 150B toward the outside of the battery, and the bent portions 150C are spaced apart from each other (see FIG. 3). The space between the bent portions results in an opening 150D in the top cover 150. Such a top cover 150 can function favorably as a terminal of the battery. For example, the top cover 150 can function as a positive terminal of the battery, and the battery can can function as a negative terminal. In such a case, the top cover 150 and the battery can can be insulated from each other. For example, the top cover can be insulated from the battery can by interposing an insulating material between the top cover and the battery can. This is merely one example, but a safety valve including the top cover can be provided for the battery can via an insulating material provided between the top cover and the battery can having a partially narrowed or constricted portion. As another example, the top cover and the battery can may be insulated from each other by the presence of a holder member (particularly an insulating holder member / not shown) provided to support the first metal member at the periphery of the safety cover provided as the first metal member (in such a case, the battery can may not be the above-mentioned "battery can having a narrowed or constricted portion in one portion," and therefore may be a non-narrowed or non-constricted battery can). The opening 150D of the top cover 150 may act as a vent hole for discharging gas generated inside the battery to the outside of the battery.The material of the top cover 150 may be a metal. For example, the top cover 150 may be made of a conductive material such as iron (Fe), steel such as SPCC, stainless steel (SUS) such as SUS430 and SUS304, nickel (Ni), aluminum (Al), and / or titanium (Ti).

[0068] A conductive member 15 extending from the electrode assembly 10 is connected to the safety valve. The conductive member 15 is electrically connected to the electrode assembly 10 (particularly one of the positive and negative electrodes) and contributes to the electrical connection between the electrode assembly 10 and the safety valve (particularly the stripper disk 130). More preferably, the conductive member 15 may be connected to a region outside the central region 130C of the stripper disk 130 corresponding to the second metal member, particularly a region on the outer periphery side of the cleavage groove 135 (i.e., a region located on the side farther away from the cleavage groove 135 with respect to the battery axis). In the safety valve, the stripper disk 130 is electrically connected to the safety cover 110 via the central region 130C, and the safety cover 110 is connected to the top cover 150 that constitutes the external terminal of the battery. Thus, the electrode assembly 10 such as the winding structure is electrically connected to the battery external terminal via the conductive member 15. In this specification, the conductive member 15 may be a member containing a metal, and may preferably be a metal member having an elongated shape. For example, the conductive member may be made of an electrode current collector of an electrode assembly, or may be a current collector lead (i.e., a lead) provided on an electrode assembly (particularly, its electrode). When the conductive member is made of an electrode current collector, the conductive member may be made of a metal portion of the electrode current collector on which no electrode material is provided. When the conductive member is made of a current collector lead, the conductive member may be made of a metal member having a thin-walled shape and / or an elongated shape. In the present invention, the conductive member that electrically connects the electrode assembly and the electrode terminal to each other may also be called a "tab". The conductive member used in such a secondary battery is preferably flexible, and may be provided in a bent and / or curved shape.

[0069] In the safety valve of the secondary battery of the present invention, the safety cover 110, the insulating member 120, and the stripper disk 130 provided as the second metal member are combined so as to be stacked on one another. More specifically, as shown in FIG. 5 and FIG. 6, the safety cover 110 and the insulating member 120 provided as the first metal member are arranged so as to be stacked on one another, and the insulating member 120 and the stripper disk 130 provided as the second metal member are arranged so as to be stacked on one another, and further, the top cover 150 is arranged so as to be stacked on the safety cover 110 provided as the first metal member. In such a safety valve combination, the stripper disk 130 provided as the second metal member is provided with a groove 135 that contributes to cleavage in the event of an abnormality. The groove has a corner contour of a specific shape inside. Specifically, the second metal member has at least two corners inside the groove in a cross-sectional view, and the shapes of the two corners are different from each other.

[0070] In this specification, "at least two corners inside the groove" refers to corners located on the groove bottom side relative to the surface of the second metal member (the member surface forming the groove opening outline) in a cross-sectional view of the groove. In other words, "at least two corners inside the groove" refers to corners provided in the groove other than the corners that are flush with the surface of the second metal member in a cross-sectional view.

[0071] The groove 135 having such a specific cross-sectional shape contributes to the breakage of the stripper disk 130 when an abnormal increase in the battery internal pressure occurs, and contributes to the subsequent inconvenient current interruption. The groove 135 provided in the stripper disk 130 of the second metal member may be a groove having an opening toward the outside when viewed along the battery axis (i.e., a groove that opens on the surface of the second metal member that is relatively closer to the first metal member). The opening of the groove may be on the surface that is closer to the element side (i.e., the opening of the groove may be on the surface that is relatively closer to the electrode assembly side). Let us assume a case where the pressure inside the battery can increases due to a side reaction such as a decomposition reaction of the electrolyte or other factors. FIG. 18 shows a state where the internal pressure of the battery, i.e., the internal pressure of the battery can, is within the normal range and the battery safety valve is not particularly operating. As shown in the figure, the stripper disk 130 and the safety cover 110 have not yet been displaced. When gas is generated inside the battery can due to a side reaction such as a decomposition reaction of the electrolyte, the gas accumulates inside the battery can, and the internal pressure of the battery can rises. If the internal pressure of the battery can continues to rise, the safety cover 110 is affected by the increase in internal pressure. This is because the stripper disk 130 has a plurality of openings 130K (see Figs. 3 and 4), and the safety cover 110 and the inside of the battery can are in fluid communication with each other. When the internal pressure of the battery can exceeds a certain pressure, the stripper disk 130 is pulled by the safety cover 110, and the stripper disk 130 is broken starting from the groove 135 (see Figs. 18 and 19). The stripper disk 130 and the safety cover 110 are connected to each other at their central regions, and the stripper disk 130, especially the central region 130C, is pulled outward in the battery axis direction due to the force received from the safety cover 110, which tries to displace due to the internal pressure. In other words, when the tensile force acting on the central region 130C exceeds a certain limit, the stripper disk 130 will break starting from the grooves 135 located around the central region.As can be seen from the forms shown in Figs. 18 and 19, when such a breakage of the stripper disk 130 occurs, the safety cover 110 is electrically separated from the non-center region 130E of the stripper disk 130 (particularly the non-center region 130E of the peripheral portion to which conductive members such as tabs and leads extending from the electrode assembly are still connected). Thus, the electrical connection between the top cover 150 and the electrode assembly is cut off, and the path of the current flowing between the electrode assembly and the top cover 150 is interrupted. In this way, the current is interrupted in the event of an abnormality such as an increase in internal pressure. If the displacement of the safety cover 110 progresses further and the safety cover itself is torn or divided, the internal pressure of the battery can is more suitably reduced. In such a case, the gas release path via the multiple openings 130K of the stripper disk 130 is particularly opened, and the gas can be released to the outside of the battery via the openings 130K.

[0072] The inventors of the present application have realized the need to improve the reliability of the rupture of the stripper disc 130. In particular, cases in which current conduction was observed even after the occurrence of a rupture sound corresponding to the rupture of the stripper disc tended to have more variation in the interruption location of the rupture groove after rupture (e.g., the groove rupture point and / or the rupture shape after rupture were more variable) or the interruption pressure was more variable (e.g., the interruption pressure was more variable as a higher interruption pressure). In other words, it was found that cases in which current conduction was observed after the rupture sound had greater interruption variation in terms of the rupture location and / or the interruption pressure compared to the desired cases in which current conduction was not observed after the rupture sound.

[0073] In response to this, the inventors of the present application have conducted extensive research and finally arrived at an invention that can suppress or avoid the above-mentioned shutoff variability during abnormal times such as an increase in the battery internal pressure. Specifically, it was found that the shutoff variability can be reduced or avoided by providing a groove in the stripper disk 130 that has at least two corners inside the groove and has the shapes of the two corners different from each other in a cross-sectional view. In other words, it was found that the provision of such a specific groove can result in a battery with improved reliability of the safety valve.

[0074] Such a unique groove will be described in more detail below with reference to the drawings. Fig. 7 shows a cross-sectional view of the stripper disk 130 together with a partially enlarged view thereof. As shown in the figure, in the cross-sectional view of the stripper disk 130, the inside of the groove 135 has two corners 135A, 135B. The present invention is characterized at least in that the shapes of the two corners in such groove 135 are different from each other.

[0075] In this specification, the term "cross-sectional view" in expressions such as "cross-sectional view of the groove" is based on a cross-section that can be obtained by cutting the safety valve along a plane along the battery axis, and is based on a cross-section obtained by cutting each member constituting the safety valve along its thickness direction, i.e., for example, a stripper disk, etc., along its thickness direction.

[0076] As shown in FIG. 8, in a cross-sectional view of the stripper disk 130 corresponding to the second metal member, the groove 135 of the stripper disk 130 has at least two corners 135A and 135B. In other words, the groove 135 of the stripper disk 130 does not have a cross-sectional contour corresponding to at least a V-notch shape. The two corners 135A and 135B have different shapes and contours, particularly when viewed in cross-section. That is, the groove 135 includes two corners 135A and 135B that are different from each other as its cross-sectional contour. At least due to the two corners 135A and 135B that are different from each other, the variation in the shutoff of the safety valve when the internal pressure of the battery can increases abnormally can be reduced or avoided. More specifically, the variation in the fracture location of the stripper disk 130 corresponding to the second metal member is reduced or avoided, and / or the variation in shutoff pressure (e.g., variation in shutoff pressure resulting in a higher shutoff pressure) is reduced or avoided, thus resulting in a battery having improved safety valve reliability.

[0077] Without being bound by any particular theory, it is believed that the reduction or avoidance of such shutoff variation is due to the fact that the stress acting on the groove of the second metal member when the internal pressure of the battery can increases abnormally can act more favorably due to the "groove having corners of different shapes inside". In particular, it is believed that the stress involved in the groove cutting of the second metal member when the internal pressure of the battery can increases abnormally can act favorably to suppress the shutoff variation due to the shape anisotropy inside such a groove. For example, it is believed that the reduction or avoidance of the shutoff variation of the safety valve in an abnormal state can be brought about by at least the occurrence of an event in which the fracture stress is more effectively applied near one of the corners due to the shape anisotropy inside the groove, such as "a groove having corners of different shapes inside". Note that in the case of a groove without such shape anisotropy, it can be said that it is easily affected by the parts and components of the safety valve and the assembly variation, and that it can be said that the fracture location due to the stress acting on the groove of the second metal member is easily varied. In this regard, in the present invention, the cleavage groove is relatively less susceptible to the effects of variations in parts and materials and assembly variations of the safety valve, and in this respect it can be said that it can contribute to reducing or avoiding shutoff variations.

[0078] In a preferred embodiment, the angle of one of the two corners in the groove of the second metal member is relatively larger than the angle of the other of the two corners in a cross-sectional view. In other words, it is preferable that the angle of the outline of one corner in a cross-sectional view of the second metal member is larger than the angle of the outline of the other corner. In the embodiment shown in Figures 8 and 9, in a cross-sectional view of the stripper disk 130 corresponding to the second metal member, the angle α of the corner 135A corresponding to one of the two corners 135A and 135B is larger than the angle β of the other corner 135B (i.e., angle α>angle β). When the angle α of the corner 135A, which is one of the two angles inside the groove 135, is larger than the angle β of the other corner 135B, the variation in the breakage location of the stripper disk 130 corresponding to the second metal member is reduced or avoided, and / or the variation in the shutoff pressure (e.g., the variation in the shutoff pressure resulting from a higher shutoff pressure) is reduced or avoided. This results in a suitable battery with improved reliability of the safety valve.

[0079] The angle of the relatively large corner 135A in the second metal member is preferably 5° to 60° larger than the angle of the relatively small corner 135B. In other words, in a cross-sectional view of the groove of the stripper disk 130 corresponding to the second metal member, the difference between the relatively large angle of the two corners and the relatively small angle of the two corners is preferably 5° to 60°. As shown in FIG. 8 and FIG. 9, when the angle of the relatively large corner 135A of the two angles in the groove 135 is α and the angle of the relatively small corner 135B is β, it is preferable that β+5°≦α≦β+60°. This is because the effect of reducing or avoiding the breakage location variation of the stripper disk 130 corresponding to the second metal member becomes more noticeable, and / or the effect of reducing or avoiding the break pressure variation (for example, the break pressure variation resulting from a higher break pressure) becomes more noticeable. More specifically, when the angle of the relatively large corner 135A is larger than the angle of the relatively small corner 135B within a difference of 5°, the effect of the shape anisotropy inside the groove is more effectively achieved. On the other hand, when the angle of the relatively large corner 135A is larger than the angle of the small corner 135B beyond a difference of 60°, the die (the die for press-molding the second metal member having the groove) tends to wear out more quickly. In other words, when β+5°≦α≦β+60°, a battery with improved reliability of the safety valve in terms of shutoff variation is easily realized while maintaining more suitable manufacturing such as suppressing die wear of the press-molding die. The relationship between angles α and β may be such that α is greater than β by 6° or more, 7° or more, 8° or more, 9° or more, or 10° or more, and α may be greater than β by up to 55°, up to 54°, up to 53°, up to 52°, up to 51°, or up to 50°.Here, as can be seen from Figures 8 and 9, the "angle" in this specification refers to the angle formed by the contour of the angle inside the groove when viewed in cross section, particularly the angle located on the hollow side of the groove (i.e., the angle on the side that is not the solid portion of the second metal component).

[0080] In other words, in a cross-sectional view of the groove of the stripper disk 130 corresponding to the second metal member, the relatively large angle of the two corners is preferably greater than 100° and less than 170°. With reference to Figs. 8 and 9, the angle α of the relatively large corner 135A of the groove 135 is preferably 100°<α≦170°, 100°<α≦165°, or 100°<α≦160°, or 105°≦α≦170°, 105°≦α≦165°, or 105°≦α≦160°, or the like. This is because the effect of reducing or avoiding the variation in the breakage location of the stripper disk 130 corresponding to the second metal member becomes more apparent, and / or the effect of reducing or avoiding the variation in the shutoff pressure (for example, the variation in the shutoff pressure resulting from a higher shutoff pressure) becomes more apparent. More specifically, when the relatively large corner 135A is greater than 100°, the effect of the shape anisotropy inside the groove is more effectively achieved, while when the relatively large corner 135A exceeds 170°, the die (the die for press-molding the second metal member having the groove) tends to wear out more quickly. In other words, when the angle of the relatively large corner 135A in the second metal member is greater than 100° and equal to or less than 170°, a battery with improved reliability of the safety valve in terms of shutoff variation can be easily realized while maintaining more suitable manufacturing such as suppressing die wear of the press-molding die.

[0081] The corner 135A having a relatively large angle is preferably positioned relatively closer to the center of the battery in the second metal member. That is, as shown in FIG. 9, in a cross-sectional view of the groove 135 of the stripper disk 130 corresponding to the second metal member, one corner having a relatively large angle (135A in the illustrated embodiment) is preferably positioned relatively closer to the battery axis side than the corner having the other angle (135B in the illustrated embodiment). With such a positioning relationship, the effect of reducing or avoiding the variation in the breakage location of the stripper disk 130 corresponding to the second metal member becomes more likely to be realized, and / or the effect of reducing or avoiding the break pressure variation (for example, the variation in the break pressure resulting from a higher break pressure) becomes more likely to be realized. That is, a battery with improved reliability of the safety valve in terms of the break variation can be easily realized.

[0082] In a preferred embodiment, the angle formed by the corner portion located relatively far from the battery axis is an acute angle. In other words, it is preferable that the groove angle located relatively farther from the battery axis is an acute angle. For example, in a cross-sectional view of the groove, when one corner portion having a relatively large angle is located relatively closer to the battery axis than the other corner portion, it is preferable that the angle at the other corner portion is an acute angle. Referring to FIG. 9, the angle β of the corner portion 135B located farther from the battery axis among the two angles inside the groove 135 is less than 90°, and may be, for example, 70°≦β<90°. In such an embodiment, the effect of reducing or avoiding the variation in the fracture location of the stripper disk 130 corresponding to the second metal member becomes more noticeable, and / or the effect of reducing or avoiding the variation in the breaking pressure (e.g., the variation in the breaking pressure resulting from a higher breaking pressure) becomes more noticeable. In other words, a battery having an improved reliability of the safety valve in terms of shutoff variability can be easily realized.

[0083] Although the different shapes of the two corners inside groove 135 have been described above in terms of "angle" and "relative positional relationship", they can also be described in terms of the characteristic contour of the second metal member. Specifically, in the present invention, in a cross-sectional view of the second metal member, the distance between the bottom contour of the groove and the contour of the inner main surface of the second metal member may be non-constant.

[0084] As shown in FIG. 10, in a cross-sectional view of the stripper disk 130 corresponding to the second metal member, the separation distance L between the bottom surface contour 137 of the groove 135 and the inner main surface contour 138 of the second metal member is not constant. Due to the non-constant separation distance characteristic of the contour associated with such a groove portion, the variability of the breakage location of the stripper disk corresponding to the second metal member is reduced or avoided, and / or the variability of the shutoff pressure (e.g., the variability of the shutoff pressure resulting in a higher shutoff pressure) is reduced or avoided. Therefore, such a groove contour characteristic may more suitably provide a battery with improved reliability of the safety valve in terms of shutoff variability.

[0085] Preferably, the separation distance is gradually shortened in the direction away from the battery axis. That is, in a cross-sectional view of the second metal member, the separation distance between the bottom surface contour of the groove and the inner main surface contour of the second metal member may be gradually shortened toward the peripheral edge of the member. Referring to FIG. 10, the separation distance L between the bottom surface contour 137 of the groove 135 and the inner main surface contour 138 of the second metal member 130 may be gradually shortened toward the outer periphery W of the battery. When the separation distance L is gradually shortened toward the outer periphery W of the battery in this way, the effect of reducing or avoiding the variation in the fracture location of the stripper disk corresponding to the second metal member becomes more likely to be realized, and / or the effect of reducing or avoiding the variation in the shutoff pressure (for example, the variation in the shutoff pressure resulting from a higher shutoff pressure) becomes more likely to be realized. Therefore, a battery with improved reliability of the safety valve in terms of shutoff variation can be easily realized. Without being bound by any particular theory, when the above-mentioned separation distance gradually becomes shorter, it can be said to be equivalent to providing a weakened point at the bottom of the groove, in particular providing a weakened point that can be more locally affected by stress (expressed from a different angle, providing an even thinner portion at the groove bottom that has a thin wall shape), and in that respect, it can be said that reduction and avoidance of interruption variation can be more effectively achieved. Note that the gradual decrease in the separation distance may be stepwise, but is preferably continuous as shown in the figure.

[0086] As can be seen from the embodiment shown in FIG. 10, the groove 135 may be a relatively deep groove, for example, the groove depth dimension may be greater than half the thickness dimension of the stripper disk 130. That is, in the present invention, the groove provided in the second metal member may have a depth dimension greater than half the thickness dimension of the second metal member. In a groove portion having such a depth dimension, the effect of reducing or avoiding the variation in the fracture location of the stripper disk corresponding to the second metal member is easily realized, and / or the effect of reducing or avoiding the break pressure variation (for example, the variation in the break pressure resulting from a higher break pressure) is easily realized. Note that the "depth" here may be based on the bottommost or deepest point of the deepest part of the groove.

[0087] In a preferred embodiment, in a cross-sectional view of the groove, one of the two corners of the target forms a rounded corner. That is, only one of the two corners in the groove of the second metal member may be a rounded corner, particularly when viewed in a cross-sectional view. In the case of the stripper disk 130 corresponding to the second metal member, only one of the two corners 135A and 135B may not have an angular shape in a cross-sectional view, but may be rounded. For example, in the embodiment shown in FIG. 11, the corner 135A is a rounded corner. This is because the effect of reducing or avoiding the breakage location variation of the stripper disk 130 corresponding to the second metal member becomes more apparent, and / or the effect of reducing or avoiding the cutoff pressure variation (for example, the cutoff pressure variation resulting from a higher cutoff pressure) becomes more apparent. In other words, a battery with improved reliability of the safety valve in terms of cutoff variation can be more easily realized.

[0088] When either of the two corners forms a rounded corner, it is preferable that the rounded corner is provided relatively closer to the inner periphery than the non-rounded corner that is not rounded in the second metal member. In other words, it is preferable that the rounded corner among the two corners in the groove of the second metal member is positioned relatively closer to the battery axis side. In the case of the stripper disk 130 shown in FIG. 11, it is preferable that the rounded corner 135A corresponding to one of the two corners 135A and 135B is positioned closer to the battery axis side than the non-rounded corner 135B. This makes it easier to realize the effect of reducing or avoiding the breakage location variation of the stripper disk corresponding to the second metal member, and / or makes it easier to realize the effect of reducing or avoiding the cutoff pressure variation (for example, the cutoff pressure variation resulting from a higher cutoff pressure). In other words, it becomes easier to realize a battery with improved reliability of the safety valve in terms of cutoff variation.

[0089] In the battery of the present invention, the groove may correspond to a groove for rupture that contributes to the safety valve when the internal pressure of the battery can rises abnormally. In order to function as a more suitable groove for rupture in the safety valve, the installation position is preferably away from the battery axis. In a preferred embodiment, the interconnection point between the first metal member and the second metal member is positioned on the battery axis, and the groove of the second metal member may be provided at a position away from the battery axis corresponding to the interconnection point between the first metal member and the second metal member. With reference to FIG. 6, the groove 135 of the stripper disk 130 is provided at a position away from the interconnection point J (member connection point positioned on the battery axis P) between the safety cover 110 corresponding to the first metal member and the stripper disk 130 corresponding to the second metal member. This makes it easier for the groove provided in the second metal member to function suitably as a groove for rupture when the internal pressure rises abnormally, and the effect caused by the above-mentioned "having at least two corners inside in a cross-sectional view, and the shapes of the two corners are different from each other" can be more clearly realized. That is, the effect of reducing or avoiding the variation in the breakage location of the stripper disk corresponding to the second metal member becomes more apparent, and / or the effect of reducing or avoiding the variation in the cutoff pressure (for example, the variation in the cutoff pressure resulting from a higher cutoff pressure) becomes more apparent. Therefore, a battery with improved reliability of the safety valve in terms of the cutoff variation can be more suitably realized.

[0090] (Battery manufacturing) The method for producing a battery according to the present invention will be described by taking a method for producing a secondary battery as an example. The secondary battery according to the present invention can be produced, for example, by the following procedure.

[0091] In preparing the positive electrode, a positive electrode active material is mixed with a positive electrode binder and a positive electrode conductor, etc., if necessary, to obtain a positive electrode mixture. Then, the positive electrode mixture is dispersed in an organic solvent, etc., to obtain a paste-like positive electrode mixture slurry. Then, the positive electrode mixture slurry is applied to one or both sides of a positive electrode current collector, and the positive electrode mixture slurry is dried to form a positive electrode active material layer. Thereafter, the positive electrode active material layer may be compression molded using a roll press, etc., if necessary. In such a case, the positive electrode active material layer may be heated, or compression molding may be repeated multiple times. In the same manner, a negative electrode can be prepared. Specifically, a negative electrode active material is mixed with a negative positive electrode binder, a negative electrode conductor, etc., to obtain a negative electrode mixture, and then the negative electrode mixture is dispersed in an organic solvent, etc., to obtain a paste-like negative electrode mixture slurry. Next, the negative electrode mixture slurry is applied to one or both sides of the negative electrode current collector, and then the negative electrode mixture slurry is dried to form a negative electrode active material layer. Thereafter, if necessary, the negative electrode active material layer is compression molded using a roll press or the like.

[0092] When assembling a secondary battery, for example, a positive electrode lead is connected to a positive electrode current collector using a welding method or the like, and a negative electrode lead is connected to a negative electrode current collector using a welding method or the like. Next, the positive electrode and the negative electrode are laminated via a separator, and then the positive electrode, the negative electrode, and the separator are wound to form a wound electrode body. Next, a center pin is inserted into the winding space of the wound electrode body. Then, while sandwiching the wound electrode body between a pair of insulating plates, the wound electrode body is stored inside the battery can together with the pair of insulating plates. In this case, one end of the positive electrode lead is connected to a safety valve using a welding method or the like, and one end of the negative electrode lead is similarly connected to the battery can using a welding method or the like. Next, an electrolyte is injected into the inside of the battery can, and the electrolyte is impregnated into the wound electrode body. Finally, a safety valve is provided at the open end of the battery can, for example, via a holder member or the like. This completes a secondary battery equipped with a safety valve.

[0093] The groove provided in the second metal member according to the present invention (i.e., the cleavage groove that acts when the internal pressure of the battery can increases abnormally) can be provided through the press die molding of the second metal member. Note that in the present invention, the cleavage groove of the second metal member has internal corners with different shapes in cross section, which is advantageous in that the reduction in die life can be more suppressed compared to when the groove has a V-shape in cross section. In other words, while die wear is relatively fast in the case of a groove having a cross-sectional contour equivalent to a so-called V-notch shape, in the present invention, such an event can be suitably suppressed.

[0094] The embodiments of the present invention have been described above. In the safety valve provided in the present invention, as described above, the first metal member, the second metal member, and the insulating member are combined together with the top cover so as to be stacked on top of each other, and the first metal member, the second metal member, and the insulating member are plate-shaped or disk-shaped members, the insulating member has a hollow portion or an opening, and the first metal member and the second metal member are connected through the hollow portion or opening of the insulating member. At least due to such a configuration, a thin safety valve is obtained, and in combination with the feature of "two corners of different shapes and angles inside the groove", the variation in the breakage location of the stripper disk is reduced or avoided, and / or the variation in the shutoff pressure (for example, the variation in the shutoff pressure resulting in a higher shutoff pressure) is reduced or avoided. Note that the embodiments of the present invention described above are merely typical examples. Therefore, the present invention is not limited to this, and it will be easily understood by those skilled in the art that various aspects are possible.

[0095] For example, in the safety valve according to the present invention, the groove provided in the second metal member may be provided together with an opening portion adjacent thereto. That is, an opening portion may be provided in the second metal member, and the opening portion and the groove may be adjacent to each other in the second metal member. The effect of reducing or avoiding the breakage point variation as a safety valve becomes more likely to be realized, and / or the effect of reducing or avoiding the shutoff pressure variation (for example, the shutoff pressure variation resulting from a higher shutoff pressure) becomes more likely to be realized. That is, a battery with improved reliability of the safety valve in terms of shutoff variation is easily realized. For example, in the exemplary embodiment shown in FIG. 12, the stripper disk 130 corresponding to the second metal member has a groove 135 and an opening portion 139, which are adjacent to each other. As shown in the figure, the groove 135 and the opening portion 139 may be adjacent to each other to form a cleavage site. In other words, the groove 135 and the opening 139 may be adjacent to each other, preferably directly adjacent to each other, to form a cleavage site (i.e., a cleavage site that acts when the internal pressure of the battery can increases abnormally). In this case, as shown in the figure, the groove 135 and the opening 139 may be disposed adjacent to each other so that an annular contour is formed from the groove 135 and the opening 139, and preferably disposed alternately adjacent to each other.

[0096] In addition, the safety valve according to the present invention has at least two corners inside the groove of the second metal member, but in the above description, reference was made mainly to the drawings in which the groove has two corners inside. In the present invention, since "at least two" means that the groove of the second metal member may have, for example, four corners inside. For example, as shown in the cross-sectional view of FIG. 13, four corners may be provided inside the groove of the second metal member, and the shapes of two corners facing each other among them may be different from each other. More specifically, in the direction perpendicular to the thickness direction of the member (i.e., the direction perpendicular to the battery axis direction), the corner 135A and the corner 135B may have different shapes from each other, and the corner 135A' and the corner 135B' may have different shapes from each other. From another perspective, when a plurality of corners, such as four corners, are provided inside the groove, the shapes of the two corners located closest to the bottom of the groove may be different from each other. Even in such an embodiment, the variation in the breakage location of the second metal member (e.g., stripper disk) is reduced or easily avoided, and / or the variation in shutoff pressure (e.g., variation in shutoff pressure resulting from a higher shutoff pressure) is reduced or easily avoided. In other words, a battery with improved reliability of the safety valve in terms of shutoff variation can be suitably provided. Note that such a groove having four corners therein can also be formed by press molding the second metal member using a die.

[0097] In the present invention, such die press molding may be performed on the premise of a so-called "warping back" process. In other words, the second metal member is removed from the die during die press molding, but the warping may be corrected prior to such demolding. More specifically, the groove in the second metal member finally obtained through the process of correcting the warping of the second metal member together with the die used for molding may be regarded as the "groove" in the present invention, that is, such a groove may be regarded as "a cleavage groove having at least two angles with different shapes inside when viewed in cross section".

[0098] Although the above description has focused on cylindrical batteries, the present invention is not necessarily limited thereto. For example, the battery according to the present invention may be a battery of another shape, such as a prismatic battery, and the effects of the present invention can be achieved in the same manner.

[0099] In addition, in the above description of the present invention, a battery can, i.e., a battery exterior body, was mentioned, but such an exterior body may have a beadless structure that does not have a beading portion. A beadless exterior body has no narrowed or constricted parts inside (particularly toward the battery axis side), so a larger space can be secured inside the exterior body for disposing the electrode assembly. In other words, a beadless exterior can in which the inside diameter dimension of the battery can is substantially constant along the battery axis can contribute to the realization of a battery with a higher energy density.

[0100] The battery of the present disclosure is as follows. <1> A battery (e.g., a primary battery or a secondary battery) having a safety valve (or a safety valve structure, a battery safety valve, or a safety valve structure), the safety valve comprising a first metal member located on the outside, a second metal member located on the inside, and an insulating member located between the first metal member and the second metal member, the first metal member and the second metal member are connected to each other so as to straddle the insulating member, A battery, wherein the second metal member has a groove in a cross-sectional view, the groove having at least two corners therein in the cross-sectional view, the two corners having different shapes from each other. <2> A battery having a safety valve, the safety valve comprising a first metal member located on an outside, a second metal member located on an inside, and an insulating member located between the first metal member and the second metal member; the first metal member and the second metal member are connected to each other so as to straddle the insulating member, A battery, wherein the second metal member has a groove in a cross-sectional view, the groove having at least two corners inside the groove in the cross-sectional view, and the angle of one of the two corners in the cross-sectional view is relatively larger than the angle of the other of the two corners. <3> In the safety valve, the first metal member, the second metal member, and the insulating member are combined together with a top cover so as to be stacked on top of each other, the first metal member, the second metal member, and the insulating member are plate-shaped or disk-shaped members, the insulating member has a hollow portion or an opening, and the first metal member and the second metal member are connected via the hollow portion or the opening of the insulating member. <1> or <2> 2. The battery according to claim 1 . <4> In the cross-sectional view of the groove, the relatively larger one angle is 5° to 60° larger than the other angle. <2> 2. The battery according to claim 1 . <5> the corner having the relatively large angle is positioned relatively closer to the battery axis side than the corner having the other angle, <2> or <2> Subordinate to <3> or <4> 2. The battery according to claim 1 . <6> In the cross-sectional view of the groove, the other angle forms an acute angle. <2> Subordinate to <3> ~ <5> 13. The battery according to claim 12, <7> In a cross-sectional view of the groove, one of the two corners forms a rounded corner. <1> ~ <6> 13. The battery according to claim 12, <8> Among the two corners, the R corner is relatively positioned closer to the battery shaft side. <7> 2. The battery according to claim 1 . <9> In a cross-sectional view of the second metal member, a distance between a bottom surface contour of the groove and an inner main surface contour of the second metal member is not constant. <1> ~ <8> 13. The battery according to claim 12, <10> The separation distance gradually decreases in a direction away from the battery axis. <9> 2. The battery according to claim 1 . <11> The second metal member has an opening, and the opening and the groove are adjacent to each other in the second metal member. <1> ~ <10> 13. The battery according to claim 12, <12> an interconnection point between the first metal member and the second metal member is positioned on a battery shaft, and the groove of the second metal member is provided at a position spaced apart from the battery shaft; <1> ~ <11> 13. The battery according to claim 12, <13> The insulating member is made of a resin material. <1> ~ <12> 13. The battery according to claim 12, <14> The battery includes a positive electrode and a negative electrode capable of absorbing and releasing lithium ions, <1> ~ <13> 13. The battery according to claim 12, EXAMPLES

[0101] The present invention will be described below with reference to examples, but the present invention is not limited to the following examples.

[0102] The present invention was verified using the following general-purpose software, which is widely used in various technical fields and has high reliability. ANSYS's coupled analysis software: Ansys 2022 R2 Verification object: Safety valve with static structure (2D semi-divided model shown in Figure 14) -Material requirements for each part of the safety valve Top cover (safety valve cover material): Fe (iron) Safety cover (first metal part): A1050 (aluminum) Stripper disc (second metal component): A1050 (aluminum) Insulation material: PBT (polybutylene terephthalate) Fixed setting: Fixed to point a in Figure 14 Contact settings: Setting the conditions under which parts or components do not penetrate each other even if they collide with each other (especially the conditions in Figures 15(A) and (B) where "points b and c do not penetrate each other" and "points b' and c' do not penetrate each other") Bond settings: Setting the conditions under which the parts do not separate even when deformed (especially in Fig. 16(A) to (D), the conditions are "d and e are bonded", "d' and e' are bonded", "d'' and e'' are bonded", and "d''' and e''' are bonded") Pressure setting: Pressure rise rate 0.2MPa / sec Maximum pressure 2MPa (especially the maximum pressure at the thick line "f" in Figure 17 is set to 2MPa)

[0103] Examples 1 to 4 correspond to "a safety valve case equipped with a stripper disc having at least two internal corners when viewed in cross section, the two corners having a cleavage groove having different shapes," while Comparative Example 1 is a safety valve case equipped with a stripper disc that does not meet this condition. The relationship between the two corners inside the stripper disc cleavage groove Example 1: One corner angle is 10° larger than the other Example 2: One corner angle is 40° larger than the other Example 3: One corner angle is 50° larger than the other Example 4: One corner is rounded Comparative Example 1: The shapes of the two corners are not different from each other / The shapes of the two corners are the same

[0104] As a battery safety valve, "variation in break location" and "variation in cutoff pressure" were evaluated. ● Evaluation of fracture location variation : The safety valve lid component (top cover) was held down with a plastic part, and hydraulic pressure was applied from the second metal component side to shut off the safety valve (n=12 pieces). The fracture locations were then visually confirmed (12 pieces x 3 locations), the fracture locations were classified, and the percentages (%) were investigated. "0%" indicates that all three fracture locations were "fractures proximal to the battery shaft" and there were no fractured grooves "fractures distal to the battery shaft", while "100%" indicates that all three fracture locations were "fractures distal to the battery shaft" or were torn on both the outside and inside (torn).

[0105] The evaluation criteria for fracture location variation (fracture location variation accompanied by "fracture closer to the battery shaft side", "fracture further from the battery shaft side" or "tearing" in terms of the fracture location and shape of the groove, etc.) are as follows: Variance of 50% or more: × -Variation of 20% or more but less than 50%: YES Less than 20% 0% or more variation: ◎

[0106] ● Evaluation of cutoff pressure variation In the evaluation of the above "variability in break locations," when the break location was found to be variable (A) was compared with the case where the break location was not found to be variable (B), and it was found that (A) tended to produce a higher break pressure than (B). For the break pressure in the case where the break location was variable (A), the average break pressure for a given number of runs was calculated as P A (kgf / cm 2 ) and the average breaking pressure P for a given number of runs when there is no variation in the break location B (kgf / cm 2 ) and obtained an index to compare them. A -P B |≧1kgf / cm 2 In the case of "Blocking pressure is 1kgf / cm 2 The results were evaluated as "large variation of 0.5 <|P A -P B |<1kgf / cm 2 In the case of "Blocking pressure is 0.5kgf / cm 2 Greater than 1kgf / cm 2 "less than" and 0<|P A -P B |≦0.5kgf / cm 2 In the case of "Clearing pressure variation 0.5kgf / cm 2 If there was no variation in the fracture location to begin with, the evaluation was made "no variation due to fracture location."

[0107] The evaluation criteria for the blocking pressure variation are as follows: -Blocking pressure is 1kgf / cm 2 More than variance (taking into account cutoff pressure tolerance): × - Breaking pressure variation is 0.5kgf / cm 2 Greater than 1kgf / cm 2 Less than: △ - Breaking pressure variation is 0.5kgf / cm 2 Below: No variation due to breakage: ◎

[0108] The overall evaluation was based on the following criteria. ◎: Includes at least one ◎ for the above "evaluation of rupture location variation" and "evaluation of break pressure variation" (no ×) 〇: Includes at least one 〇 for the above "evaluation of rupture location variation" and "evaluation of break pressure variation", but no ◎ (and no ×) ×: Includes at least one × for the above "evaluation of rupture location variation" and "evaluation of break pressure variation"

[0109] The results are shown in Table 1 below. [Table 1]

[0110] From the results in Table 1, it was found that when the two corners inside the cleavage groove of the stripper disk are different from each other, it is possible to exhibit shutoff characteristics with reduced shutoff variability in terms of the rupture point and / or shutoff pressure. In other words, it was found that the safety valve according to the present invention suppresses or avoids shutoff variability in abnormal cases such as an increase in the battery internal pressure, and thus a battery with a higher reliability of the safety valve in terms of shutoff variability can be more suitably produced.

[0111] The effects of the above embodiment are merely exemplary, and the present invention is not limited to the above, and may have additional effects. [Industrial Applicability]

[0112] The battery according to the present invention (such as a primary battery and a secondary battery) can be typically used in applications requiring the use of electrical energy. For example, the secondary battery according to the present invention can be used in various fields in which power storage is expected. By way of example only, the battery of the present invention can be used in the electrical, information, and communication fields in which electrical and electronic devices are used (for example, electrical and electronic devices fields or mobile device fields including mobile phones, smartphones, notebook computers, digital cameras, activity meters, arm computers, electronic paper, wearable devices, and small electronic devices such as RFID tags, card-type electronic money, and smart watches), household and small industrial applications (for example, power tools, golf carts, household, nursing care, and industrial robots), large industrial applications (for example, forklifts, elevators, and port cranes), transportation systems (for example, hybrid cars, electric cars, buses, trains, electrically assisted bicycles, and electric motorcycles), power system applications (for example, various power generation, road conditioners, smart grids, and general household installation type power storage systems), medical applications (medical devices such as earphone hearing aids), pharmaceutical applications (medical management systems), as well as the IoT field, and space and deep sea applications (for example, space probes, submersible research vessels, and the like). [Explanation of symbols]

[0113] 10 Electrode assembly 11 Positive electrode 12 Negative electrode 13 Separator 15 Conductive materials 50 Battery Can 51 Open end of battery can 52 Battery can closure end 100 Safety valve 110 First metal member (e.g., safety cover) 110C Central region of first metal member (e.g., safety cover) 120 Insulating materials 120C Openings / Opening Areas in Insulating Materials 130 Second metal member (e.g., stripper disk) 130C Central region of second metal member (e.g., stripper disk) 130K Opening of second metal member (e.g. stripper disk) 130E Non-central region of second metal member (e.g., stripper disk) 135 Groove (especially cleavage groove) of second metal member (e.g. stripper disk) 135A, 135B Two inner corners of the groove (especially the cleavage groove) 135A', 135B' Two inner corners of the groove (especially the cleavage groove) α, β: Cross-sectional view angles of two corners inside a groove (especially a groove for cleavage) 137 Bottom contour of groove (especially cleavage groove) 138 Inner main surface contour of second metal member (e.g. stripper disk) L Distance between bottom surface contour and inner main surface contour 139 Openings (especially openings constituting cleavage sites) J: An interconnection point between a first metal member (e.g., a safety cover) and a second metal member (e.g., a stripper disk) 150 Top cover 150A Top cover protrusion 150B Top cover flat plate 150C Top cover bend 150D Top cover opening W Battery outer circumference direction a Fixed part in verification conditions using Ansys 2022 R2 b, c Non-penetrating part under verification conditions using Ansys 2022 R2 b', c' Non-penetrating part under verification conditions using Ansys 2022 R2 d,e Bond part under verification conditions using Ansys 2022 R2 d', e' Bond part under verification conditions using Ansys 2022 R2 d'', e'' Bond part under verification conditions using Ansys 2022 R2 d''', e''' Bond part under verification conditions using Ansys 2022 R2 f Maximum pressure part under verification conditions using Ansys 2022 R2 1000 secondary battery P battery axis

Claims

1. A battery having a safety valve, the safety valve comprises a first metal member located on an outside, a second metal member located on an inside, and an insulating member located between the first metal member and the second metal member, the first metal member and the second metal member are connected to each other so as to straddle the insulating member, A battery, wherein the second metal member has a groove in a cross-sectional view, the groove having at least two corners therein in the cross-sectional view, the two corners having different shapes from each other.

2. A battery having a safety valve, the safety valve comprises a first metal member located on an outside, a second metal member located on an inside, and an insulating member located between the first metal member and the second metal member, the first metal member and the second metal member are connected to each other so as to straddle the insulating member, A battery, wherein the second metal member has a groove in a cross-sectional view, the groove having at least two corners inside the groove in the cross-sectional view, and the angle of one of the two corners in the cross-sectional view is relatively larger than the angle of the other of the two corners.

3. 3. The battery of claim 1, wherein the safety valve is configured such that the first metal member, the second metal member and the insulating member are combined so as to be stacked together with a top cover, the first metal member, the second metal member and the insulating member are plate-shaped or disk-shaped members, the insulating member has a hollow portion or an opening, and the first metal member and the second metal member are connected via the hollow portion or the opening of the insulating member.

4. The battery according to claim 2 , wherein in the cross-sectional view of the groove, the relatively larger one angle is 5° to 60° larger than the other angle.

5. 3. The battery according to claim 2, wherein the one corner having the relatively larger angle is positioned relatively closer to the battery axis than the other corner having the other angle.

6. The battery according to claim 5 , wherein the other angle is an acute angle in the cross-sectional view of the groove.

7. The battery according to claim 1 , wherein in the cross-sectional view of the groove, one of the two corners forms a rounded corner.

8. The battery according to claim 7 , wherein the rounded corner of the two corners is positioned relatively closer to the battery axis side.

9. The battery according to claim 1 or 2, wherein in the cross-sectional view of the second metal member, a distance between a bottom surface contour of the groove and an inner main surface contour of the second metal member is not constant.

10. 10. The battery of claim 9, wherein the separation distance decreases progressively in a direction away from the battery axis.

11. The battery according to claim 1 or 2, wherein the second metal member has an opening, and the opening and the groove are adjacent to each other in the second metal member.

12. 3. The battery according to claim 1, wherein the interconnection point between the first metal member and the second metal member is positioned on a battery shaft, and the groove of the second metal member is provided at a position spaced apart from the battery shaft.

13. The battery according to claim 1 , wherein the insulating member is made of a resin material.

14. 3. The battery according to claim 1, wherein the battery comprises a positive electrode and a negative electrode capable of absorbing and releasing lithium ions.

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